CN1773989A - Greenfield preamble format for multiple-input multiple-output wireless communication - Google Patents

Abstract

The present invention discloses a method for multiple input multiple output wireless communication begins by determine the protocol utilized by each of the wireless communication devices within the proximal region. The method continues by determining whether the protocols of the wireless communication devices within a proximal region are of a like protocol. The method continues by determining the number of transmit antennas. The method continues, when the protocols of the wireless communication devices within a proximal region are of the like protocol, formatting preamble of a frame of a wireless communication utilizing at least one of cyclic shifting of symbols, cyclic shifting of tones, sparse tone allocation, and sparse symbol allocation based on the number of transmit antennas.

Description

Greenfield preamble format for multiple-input multiple-output wireless communication

【Technical field】

The present invention relates to a wireless communication system, in particular to a method and equipment for supporting multiple wireless communication protocols in a wireless local area network.

【Background technique】

Communication systems are well known to support wired and wireless communications between wireless and/or wired communication devices. Said communication systems range from national and/or international mobile phone systems to the Internet to point-to-point indoor wireless networks. Each type of communication system is built and operates according to one or more communication standards. For example, a wireless communication system can operate in compliance with one or more standards including, but not limited to: IEEE802.11, Bluetooth, Advanced Mobile Phone Service (AMPS), Digital Advanced Mobile Phone Service (Digital AMPS), Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Local Multiple Point Distribution System (LMDS), Multichannel Multiple Point Distribution System (MMDS) and/or variations/variations thereof.

Depending on the type of wireless communication system, wireless communication devices, such as mobile phones, two-way transceivers, personal digital assistants (PDAs), personal computers (PCs), laptops, home entertainment devices, etc., are directly or indirectly communicatively connected to other wireless communication equipment. For direct communication (that is, so-called point-to-point communication), the wireless communication devices participating in the communication tune their receivers and transmitters to the same channel or channels (for example, multiple radio frequencies (RF) in the wireless communication system one of the carriers), and communicate on that channel. For indirect wireless communication, each wireless communication device communicates directly with an associated base station (eg, for mobile services) and/or an associated access point (eg, for an indoor or in-building wireless network) via an assigned channel. To accomplish communication links between wireless communication devices, associated base stations and/or associated access points communicate directly with each other via a system controller, public switched telephone network, the Internet, and/or some other wide area network.

In order to participate in wireless communication, each wireless communication device includes a built-in wireless transceiver (that is, receiver and transmitter) or is coupled to an associated wireless transceiver (such as a wireless station of an indoor or in-building wireless communication network). , RF modem, etc.). As is known in the art, a transmitter includes a data modulation stage, one or more intermediate frequency stages and a power amplifier. The data modulation stage converts the raw data into a baseband signal according to a specific wireless communication standard. One or more intermediate frequency stages mix the baseband signal with one or more local oscillators and generate a radio frequency signal. The power amplifier amplifies the RF signal before transmitting it through the antenna.

Also as known in the art, the receiver is coupled to the antenna and includes a low noise amplifier, one or more intermediate frequency stages, filtering stages and data recovery stages. A low noise amplifier receives an incoming RF signal through an antenna and amplifies it. One or more intermediate frequency stages mix the amplified radio frequency signal with one or more local oscillators to convert the amplified radio frequency signal to a baseband signal or an intermediate frequency (IF) signal. The filter stage filters the baseband signal or the IF signal to attenuate unwanted out-of-band signals to produce a filtered signal. The data recovery stage recovers the original data from the filtered signal according to a specific wireless communication standard.

Still, as is known in the art, the standards to which wireless communication devices within a wireless communication system comply can vary. For example, as the IEEE 802.11 specification develops from IEEE 802.11 to IEEE 802.11b, IEEE 802.11a, and then to IEEE 802.11g, wireless communication devices that comply with IEEE 802.11b and wireless communication devices that comply with IEEE 802.11g may exist in the same wireless local area network middle. As another example, a wireless communication device conforming to IEEE 802.11a and a wireless communication device conforming to IEEE 802.11g may exist in the same wireless local area network. When legacy devices (i.e., devices conforming to earlier versions of the standard) exist on the same WLAN as devices conforming to later versions of the standard, a mechanism is used to ensure that when newer versions of the device are The legacy device can know when the wireless channel is used, thereby avoiding collisions.

For example, backward compatibility for legacy devices is only achieved at the physical layer (in the case of IEEE 802.11b) or the medium access control layer (in the case of IEEE 802.11g). At the physical layer, backward compatibility is achieved by reusing the physical layer preamble from previous standards. In this example, the legacy device will decode the preamble portion of all signals, which provides enough information to determine whether the wireless channel is occupied for a certain period of time, so even if the legacy device cannot fully demodulate and/or decode Transmitting frames also avoids collisions.

At the media access control layer, backward compatibility of legacy devices is achieved by forcing devices conforming to newer versions of the standard to transmit special frames using the mode or data rate used by legacy devices. For example, the newer device may send a Clear to Send (CTS)/Ready to Send (RTS) exchange frame and/or a Clear to Send (CTS-to-self) frame as in IEEE802.11g Used. These special frames contain information to set the network allocation vector (NAV) of the legacy device so that the legacy device knows when the wireless channel is being used by a newer version of the wireless station.

The two existing mechanisms for achieving backward compatibility have a certain performance penalty relative to the performance achieved by non-backward compatible devices, and the two existing mechanisms can only be used independently of each other .

Therefore, there is a need for a method and apparatus for supporting multiple protocols in a wireless communication system, including a wireless local area network.

【Content of invention】

The above needs and others are substantially satisfied by the preamble format for multiple-input multiple-out wireless communication of the present invention. In one embodiment, a method of multiple-input multiple-output wireless communication begins with determining protocols of wireless communication devices within a vicinity. The method then determines whether the communication protocols of the wireless communication devices within the vicinity belong to the same protocol. The method continues with determining the number of transmit antennas. The method continues, when the communication protocols of the wireless communication devices in the nearby area belong to the same protocol, according to the number of antennas, using at least one of character cyclic shift, tone cyclic shift, loose tone configuration and loose character configuration The preamble of the wireless communication frame is formatted.

According to one aspect of the present invention, a method for multiple-input multiple-output wireless communication is provided, the method comprising:

Determine the protocol of wireless communication devices in the vicinity;

determining whether the protocols of the wireless communication devices in the vicinity belong to the same protocol;

Determine the number of transmit antennas;

When the protocols of the wireless communication devices in the nearby area belong to the same protocol, according to the number of the transmitting antennas, using at least one of character cyclic shift, pitch cyclic shift, loose tone configuration and loose character configuration The preamble of the frame for wireless communication is formatted.

Preferably, the method comprises: when the protocols of the wireless communication devices in the vicinity belong to the same protocol, formatting the preamble of the frame of the wireless communication in the following format: the first part of the frame adopts legacy Format: according to the number of transmit antennas, at least one of character cyclic shift, tone cyclic shift, loose tone configuration and loose character configuration is adopted for the remaining part of the preamble of the frame.

According to an aspect of the present invention, there is provided a method for generating a frame preamble for MIMO wireless communication, the method comprising, for each transmitting antenna of MIMO wireless communication:

generating a carrier detect field, wherein the carrier detect field is cyclically shifted from transmit antenna to transmit antenna;

generating a first channel sounding field, wherein the first channel sounding field is cyclically shifted from transmit antenna to transmit antenna; and

Generate a signal field.

Preferably, the method includes: generating a single guard interval between said first channel sensing field and said signal field.

Preferably, the method includes: generating a single guard interval between said first channel sensing field and said signal field.

Preferably, the method includes:

generating a short training sequence (STS) following a legacy (legacy) wireless communication protocol as the carrier sounding field;

generating two long training sequences (LTS) following a legacy wireless communication protocol as the first channel sensing field, wherein the first long training sequence of the two long training sequences is cyclically shifted from transmit antenna to transmit antenna bits, the second long training sequence in the two long training sequences is cyclically shifted.

Preferably, the method includes:

A second sounding field is generated, wherein the second channel sounding field is cyclically shifted from transmit antenna to transmit antenna.

Preferably, the method includes:

A long training sequence following a legacy wireless communication protocol is generated as the second channel sensing field, wherein the second channel sensing field is cyclically shifted from transmit antenna to transmit antenna.

Preferably, the method includes:

generating two long training sequences following a legacy wireless communication protocol as the second channel sensing field, wherein, from transmitting antenna to transmitting antenna, the first long training sequence of the two long training sequences is cyclically shifted, so The second long training sequence in the two long training sequences is cyclically shifted.

Preferably, the method includes:

The signal field is encoded by at least one of rate 1/2 binary phase shift keying and rate 1/2 quadrature phase shift keying.

According to an aspect of the present invention, a radio frequency transmitter includes:

a baseband processing module operably coupled to convert outbound data into outbound character strings;

a transmitter portion operatively coupled to convert said outbound character string into an outbound radio frequency signal, said baseband processing module further operatively coupled to:

generating a carrier sounding field, wherein the carrier sounding field is cyclically shifted from transmit antenna to transmit antenna;

generating a first channel sensing field, wherein the first channel sensing field is cyclically shifted from transmit antenna to transmit antenna;

Generate a signal field.

Preferably, the baseband processing module is further operatively coupled to generate a double guard interval between the carrier sounding field and the first channel sensing field.

Preferably, said baseband processing module is further operatively coupled to generate a single guard interval between said first channel sense field and signal field.

Preferably, the baseband processing module is further operably coupled for:

generating a short training sequence following a legacy (legacy) wireless communication protocol as the carrier sounding field;

generating two long training sequences following a legacy wireless communication protocol as the first channel sensing field, wherein, from transmit antenna to transmit antenna, the first long training sequence of the two long training sequences is cyclically shifted, so The second long training sequence in the two long training sequences is cyclically shifted.

Preferably, the baseband processing module is further operably coupled for:

A long training sequence following a legacy wireless communication protocol is generated as the second channel sensing field, wherein the second channel sensing field is cyclically shifted from transmit antenna to transmit antenna.

Preferably, the baseband processing module is further operably coupled for:

generating two long training sequences following a legacy wireless communication protocol as the second channel sensing field, wherein, from transmitting antenna to transmitting antenna, the first long training sequence of the two long training sequences is cyclically shifted, so The second long training sequence in the two long training sequences is cyclically shifted.

Preferably, the baseband processing module is further operably coupled for:

The signal field is encoded by at least one of rate 1/2 binary phase shift keying and rate 1/2 quadrature phase shift keying.

【Description of drawings】

1 is a schematic block diagram of a wireless communication system according to the present invention;

FIG. 2 is a schematic block diagram of a wireless communication device according to the present invention;

3 is a schematic block diagram of another wireless communication device according to the present invention;

Fig. 4 is a schematic block diagram of a radio frequency transmitter according to the present invention;

FIG. 5 is a schematic block diagram of a radio frequency receiver according to the present invention;

6 is a schematic block diagram of a wireless communication device communicating with an access point according to the present invention;

Figure 7 is a schematic diagram of one type of wireless communication according to the present invention;

8 is a schematic diagram of a type of multiple-input multiple-output wireless communication according to the present invention;

FIG. 9 is a schematic diagram of a preamble of a frame using cyclic shifts using two transmit antennas according to the present invention;

10 is a schematic diagram of a preamble for a frame using loose characters and/or tones using two transmit antennas according to the present invention;

11 is a schematic diagram of a preamble of a frame using cyclic shifts using three transmit antennas according to the present invention;

12 is another schematic diagram of a preamble of a frame using cyclic shifts using three transmit antennas according to the present invention;

13 is a schematic diagram of a preamble for a frame using loose characters and/or tones using three transmit antennas in accordance with the present invention;

14 is a schematic diagram of a preamble of a frame using cyclic shifts using four transmit antennas according to the present invention;

FIG. 15 is another schematic diagram of a preamble using a cyclically shifted frame using four transmit antennas according to the present invention;

16 is a schematic diagram of a preamble for a frame using loose characters and/or tones using four transmit antennas according to the present invention;

Figure 17 is a schematic diagram of another type of wireless communication according to the present invention;

18 is a schematic diagram of another type of multiple-input multiple-output (MIMO) wireless communication according to the present invention;

19 is a schematic diagram of a preamble of a frame using a cyclic shift using two transmit antennas using a legacy part according to the present invention;

20 is a schematic diagram of a preamble of a frame using a cyclic shift using three transmit antennas of a legacy part according to the present invention;

21 is a schematic diagram of a preamble of a frame using a cyclic shift using four transmit antennas of a legacy part according to the present invention;

22 is a schematic diagram of another type of wireless communication according to the present invention;

23 is a schematic diagram of yet another type of multiple-input multiple-output (MIMO) wireless communication according to the present invention;

FIG. 24 is a logic diagram of a method for communicating with multiple protocols according to the present invention;

25 is a logic diagram of a method for monitoring the success of multi-protocol wireless communication according to the present invention;

Fig. 26 is a logic diagram of a method for a wireless communication device to participate in multi-protocol wireless communication according to the present invention;

Fig. 27 is a logic diagram of another method for a wireless communication device to participate in multi-protocol wireless communication according to the present invention;

Fig. 28 is a logic diagram of another method for a wireless communication device to participate in multi-protocol wireless communication according to the present invention;

Fig. 29 is a schematic diagram of simultaneous second channel sensing according to the present invention;

Fig. 30 is a schematic diagram of another simultaneous second channel monitoring according to the present invention;

Fig. 31 is a schematic diagram of yet another simultaneous second channel monitoring according to the present invention;

Fig. 32 is a schematic diagram of yet another simultaneous second channel monitoring according to the present invention;

Figure 33 is a schematic diagram of guard intervals and training sequences according to the present invention;

Fig. 34 is a schematic diagram of cyclic shift according to the present invention;

35 is a schematic diagram of preambles for two transmit antennas according to the present invention;

36 is a schematic diagram of preambles for three transmit antennas according to the present invention;

37 is another schematic diagram of preambles for three transmit antennas according to the present invention;

FIG. 38 is a schematic diagram of preambles for four transmit antennas according to the present invention.

【Detailed ways】

1 is a block schematic diagram of a communication system 10 that includes a plurality of base stations and/or access points 12-16, a plurality of wireless communication devices 18-32, and a network hardware 34. As shown in FIG. The wireless communication devices 18-32 may be laptop computers 18 and 26, personal digital assistant hosts 20 and 30, personal computer hosts 24 and 32, and/or mobile phone hosts 22 and 28. Details of these wireless communication devices will be described in more detail with reference to FIG. 2 and/or FIG. 3 .

Base stations or access points 12 - 16 are operatively coupled to network hardware 34 through local area network connections 36 , 38 and 40 . Network hardware 34, which may be a router, switch, bridge, modem, system controller, or the like, provides wide area network connectivity 42 for communication system 10. Each base station or access point 12-16 has a corresponding antenna or antenna array for communicating with wireless communication devices in its area, commonly referred to as a basic service set (BBS). Typically, a wireless communication device registers with a particular base station or access point 12-16 in order to receive service from the communication system 10. For direct communication (ie, point-to-point communication), wireless communication devices communicate directly through assigned channels to create a multi-hop (ad-hoc) network.

Typically, base stations are used in mobile phone systems and similar types of systems, while access points are used in indoor or building wireless networks. Regardless of the type of communication system, each wireless communication device includes a built-in radio and/or is coupled to a radio. The wireless receiving apparatus includes a highly linear amplifier and/or programmable multi-stage amplifiers as disclosed herein to improve performance, reduce cost, reduce size and/or enhance broadband applications.

Fig. 2 is a schematic block diagram of a wireless communication device. The wireless communication device includes a host device 18 - 32 and an associated radio 60 . For the mobile phone host, the wireless transceiver 60 is a built-in component. For a personal digital assistant mainframe, a laptop computer mainframe and/or a personal computer mainframe, the wireless transceiver 60 can be a built-in component or an external component.

As shown, the host device 18 - 32 includes a processing module 50 , memory 52 , wireless transceiver interface 54 , input interface 58 and output interface 56 . The processing module 50 and memory 52 execute corresponding instructions, typically made by a host device. For example, for a mobile phone host device, the processing module 50 executes corresponding communication functions according to specific mobile phone standards.

The radio interface 54 allows data to be received from and transmitted to the radio 60 . For data received from the radio 60 (eg, inbound data), the radio interface 54 provides the data to the processing module 50 for further processing and/or to the output interface 56 . Output interface 56 provides a connection to an output display device (eg, display, monitor, speaker, etc.) for displaying received data. The radio interface 54 also provides data from the processing module 50 to the radio 60 . Processing module 50 can receive outbound data from input devices (eg, keyboard, keypad, microphone, etc.) via input interface 58, or generate data itself. For the data received via the input interface 58 , the processing module 50 can execute corresponding host functions based on the data and/or send the data to the wireless transceiver device 60 through the wireless transceiver interface 54 .

The wireless transceiver 60 includes a host interface 62, a digital receiver processing module 64, a memory 75, a digital transmitter processing module 76 and a wireless transceiver. The wireless transceiver includes an analog-to-digital converter 66, a filter/gain module 68, an intermediate frequency mixing down-conversion stage 70, a receive filter 71, a low-noise amplifier 72, a transmitter/receiver switch 73, and a local oscillator module 74 , a digital-to-analog converter 78 , a filter/gain module 80 , an intermediate frequency mixing up-conversion stage 82 , a power amplifier 84 , a transmit filter module 85 and an antenna 86 . Antenna 86 may be a single antenna controlled by transmitter/receiver switch 73 shared by the transmit and receive paths, or may include separate antennas for the transmit and receive paths. The implementation of the antenna depends on the particular standard to which the wireless communication device complies.

Digital receiver processing module 64 and digital transmitter processing module 76, in combination with operational instructions stored in memory 75, perform digital receiver functions and digital transmitter functions, respectively, in accordance with one or more wireless communication standards. The digital receive processing module 64 and the digital transmit processing module 76 further perform one or more aspects of the functions described in FIGS. 3-11 . Digital receiver functions include, but are not limited to, digital IF to baseband conversion, demodulation, constellation demapping, decoding and/or descrambling. Digital transmitter functions include, but are not limited to, scrambling, encoding, constellation mapping, modulation, and/or digital baseband to IF conversion. Digital receiver and transmitter processing modules 64 and 76 may be implemented with one shared processing device, separate processing devices, or multiple processing devices. Such processing devices may be microprocessors, microcontrollers, digital signal processors, microcomputers, central processing units, field programmable gate arrays, programmable logic devices, state machines, logic circuits, analog circuits, digital circuits and and/or any device that controls signals (analog and/or digital) based on operational instructions. The memory 75 may be a single memory device or multiple memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. It should be noted that when the processing modules 64 and/or 76 execute one or more functions through state machines, analog circuits, digital circuits and/or logic circuits, the memories storing corresponding operation instructions are embedded in the state machines, analog circuits, in digital circuits and/or logic circuits.

In operation, the radio 60 receives outbound data 94 from a host device via the host interface 62 . Host interface 62 sends outbound data 94 to digital transmitter processing module 76, which complies with a particular wireless communication standard (e.g., IEEE 802.11 and its versions, Bluetooth and its versions, etc.) Outbound data 94 is processed to produce digital transmission format data 96 . The digital transmission format data 96 will be a digital baseband signal or a digital low intermediate frequency signal, typically in the frequency range from 100 KHz to several MHz.

A digital-to-analog converter 78 converts the digital transmission format data 96 from the digital domain to the analog domain. Filter/gain block 80 filters and/or adjusts the gain of the analog signal before providing it to upconversion mixing stage 82 . From the transmitter local oscillator 83 provided by the local oscillator module 74, the up-conversion mixing stage 82 converts the analog baseband or low intermediate frequency signal into a radio frequency signal. Power amplifier 84 amplifies the RF signal and generates outbound RF signal 98 , which is filtered by transmitter filter module 85 . Antenna 86 transmits outbound radio frequency signals 98 to target devices, such as base stations, access points, and/or other wireless communication devices.

The radio 60 also receives, via the antenna 86, inbound radio frequency signals 88 transmitted by base stations, access points and/or other wireless communication devices. Antenna 86 provides inbound RF signal 88 via transmitter/receiver switch 73 to receiver filtering module 71 , which bandpass filters inbound RF signal 88 . Receive filtering module 71 provides the filtered radio frequency signal to low noise amplifier 72, which amplifies the signal 88 and produces an amplified inbound radio frequency signal. The low noise amplifier 72 provides the amplified inbound radio frequency signal to the intermediate frequency mixing module 70, and the down conversion module 70 directly converts the amplified inbound radio frequency signal into Inbound low-IF signal or baseband signal. The down conversion module 70 provides the inbound low-IF or baseband signal to the filter/gain module 68 . Filter/gain module 68 filters and/or amplifies the inbound low-IF signal or the inbound baseband signal to produce a filtered inbound signal.

An analog-to-digital converter 66 converts the filtered inbound signal from the analog domain to the digital domain to produce data 90 in a digital receive format. Depending on the particular wireless communication standard implemented by the radio 60 , the digital receive processing module 64 decodes, descrambles, demaps and/or demodulates the digital receive format data 90 to retrieve the inbound data 92 . The host interface 62 provides the retrieved inbound data 92 to the host device 18-32 via the wireless transceiver interface 54.

As known by those of ordinary skill in the art, the wireless communication device shown in FIG. 2 may be implemented using one or more integrated circuits. For example, a host device can be implemented on an integrated circuit. Digital receiver processing module 64, digital transmitter processing module 76 and memory 75 may be implemented on a second integrated circuit. Other components of the radio 60 except the antenna can be realized on the third integrated circuit. As another example, radio 60 may be implemented on a single integrated circuit. As yet another example, the host device's processing module 50 and the digital receiver and transmitter processing modules 64 and 76 may be a common processing device implemented on a single integrated circuit. Still further, memories 52 and 75 may be implemented on a single integrated circuit and/or on the same single integrated circuit as a common processing block for processing block 50 and digital receiver and transmitter processing blocks 64 and 76 .

FIG. 3 is a schematic block diagram of another wireless communication device of the present invention. The wireless communication device includes a host device 18 - 32 and an associated radio 60 . For the mobile phone host, the radio transceiver 60 is a built-in component. For a personal digital assistant mainframe, a laptop computer mainframe and/or a personal computer mainframe, the wireless transceiver 60 can be a built-in component or an external component.

The wireless transceiver 60 includes a host interface 62, a baseband processing module 63, a memory 65, a plurality of radio frequency transmitters 67, 69, 71, a sending/receiving conversion module 73, a plurality of antennas 81, 83, 85, and a plurality of radio frequency receivers 75, 77, 79 and local oscillator module 99. The baseband processing module 63 performs the function of the digital receiver and the function of the digital transmitter respectively in combination with the operating instructions stored in the memory 65 . Digital receiver functions include, but are not limited to, digital IF to baseband conversion, demodulation, constellation demapping, decoding, deinterleaving, fast Fourier transform, cyclic prefix removal, spatial and temporal decoding and/or Descrambling (descrambling). Digital transmitter functions include, but are not limited to, scrambling, encoding, interleaving, constellation mapping, modulation, inverse fast Fourier transform, cyclic prefix addition, space and time encoding, and/or digital baseband to IF conversion. The baseband processing module 63 may be implemented with one or more processing devices. Such processing devices may be microprocessors, microcontrollers, digital signal processors, microcomputers, central processing units, field programmable gate arrays, programmable logic devices, state machines, logic circuits, analog circuits, digital circuits and and/or any device that manipulates signals (analog and/or digital) based on operational instructions. Memory 66 may be a single storage device or multiple storage devices. Such a storage device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. It should be noted that when the processing module 63 executes one or more functions through the state machine, analog circuit, digital circuit and/or logic circuit, the memory storing the corresponding operation instruction is embedded in the state machine, analog circuit, digital circuit and/or logic circuit. and/or logic circuits in circuits.

In operation, the radio 60 receives outbound data 87 from a host device via the host interface 62 . The baseband processing module 63 receives the outbound data 87 and generates one or more outbound character strings 89 based on the mode selection signal 101 . The mode select signal 101 will indicate a particular mode as shown in the mode select table. For example, the mode selection signal 101, see Table 1, might indicate a frequency band of 2.4 GHz, a channel bandwidth of 20 or 22 MHz and a maximum bit rate of 54 megabits per second. Within this general category, the mode select signal will further indicate a specific rate, ranging from 1 megabit per second to 54 megabits per second. Additionally, the mode select signal will indicate a particular modulation type, which includes, but is not limited to, Barker code modulation, BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), CCK (Complementary Code Keying ), 16QAM (Quadrature Amplitude Modulation) and/or 64QAM. As shown in Table 1, the coding rate is also provided, along with the number of coded bits per subcarrier (NBPSC), the number of coded bits per OFDM (orthogonal frequency division multiplexing) Data bits (NDBPS) of OFDM characters, decibel level of error vector (EVM), sensitivity expressing maximum received power required to obtain target packet error rate (e.g. 10% for IEEE802.11a), adjacent channel rejection (ACR ) and an alternate adjacent channel rejection (AACR).

The mode selection signal may also indicate the selection of a specific communication channel for the corresponding mode, as shown in Table 2, which is the selection of the communication channel based on the information in Table 1. As shown, Table 2 includes channel numbers and corresponding center frequencies. The mode selection signal may further indicate a power spectral density mask value (power spectral density mask value) shown in Table 3 for Table 1. Alternatively, the mode selection signal may indicate the rate in Table 4, the frequency band is 5 GHz, the channel bandwidth is 20 MHz, and the maximum bit rate is 54 megabits per second. If this is a specific mode selection, the communication channel selection is shown in Table 5. As a further option, the mode selection signal 102 may indicate that the frequency band is 2.4GHz, the channel bandwidth is 20MHz, and the maximum bit rate is 192 megabits per second, as shown in Table 6. In Table 6, multiple antennas can be utilized to achieve higher bandwidth. In this example, the mode selection also indicates the number of antennas used. Table 7 shows the selection of communication channels set for Table 6. Table 8 shows another mode option with a frequency band of 5 GHz, a channel bandwidth of 20 MHz, and a maximum bit rate of 192 Mbits per second. The corresponding Table 8 includes various bit rates ranging from 12 Mbits per second to 216 Mbits per second using 2 to 4 antennas and indicated space-time coding rates, as shown in the table. Table 9 shows the selection of communication channels of Table 8. The mode selection signal 102 can also indicate a specific operation mode as shown in Table 10, the corresponding frequency band is 5 GHz, the channel bandwidth is 40 MHz, and the maximum bit rate is 486 Mbits per second. As shown in Table 10, the bit rate can be selected from a range of 13.5 Mbit/s to 486 Mbit/s using 1-4 antennas and corresponding space-time coding rates. Table 10 also shows the coding rate and number of subcarrier coding bits for a particular modulation scheme. Table 11 provides the power spectral density mask values of Table 10. Table 12 provides a selection of the communication channels of Table 10.

The baseband processing module 63 generates one or more outbound character strings 89 from the outbound data 87 based on the mode select signal 101 . For example, if the mode select signal 101 indicates the use of a single antenna for the particular mode selected, the baseband processing module 63 will generate a single outbound string 89 . Optionally, if the mode selection signal indicates 2, 3 or 4 antennas, the baseband processing module 63 will generate 2, 3 or 4 outbound character strings 89 corresponding to the number of antennas from the outbound data 87 .

Depending on the number of outbound character strings 89 generated by the baseband processing module 63 , a corresponding number of radio frequency transmitters 67 , 69 , 71 are activated to convert the outbound character strings 89 into outbound radio frequency signals 91 . Implementation of the radio frequency transmitters 67, 69, 71 will be further described with reference to FIG. 4 . The transmit/receive conversion module 73 receives the outbound RF signals 91 and provides each outbound RF signal to a corresponding antenna 81 , 83 and 85 .

When the wireless transceiver device 60 works in the receiving mode, the transmitting/receiving conversion module 73 receives one or more inbound radio frequency signals through the antennas 81 , 83 and 85 . The transmit/receive conversion module 73 provides the inbound radio frequency signal 93 to one or more radio frequency receivers 75 , 77 , 79 . RF receivers 75 , 77 , 79 (described in more detail with reference to FIG. 4 ) convert the inbound RF signal 93 into a corresponding number of inbound character strings 95 . The number of inbound strings 95 corresponds to the particular mode in which the data was received (the mode can be any of those shown in Tables 1-12). The baseband processing module 63 receives the inbound character string 95 and converts it into inbound data 97, which is provided to the host device 18-32 via the host interface 62.

As known to those of ordinary skill in the art, the wireless communication device shown in FIG. 3 can be implemented by using one or more integrated circuits. For example, a host device can be implemented on an integrated circuit. The baseband processing module 63 and memory 65 can be implemented on the second integrated circuit. Other components of the radio 60 except the antenna can be realized on the third integrated circuit. As an alternative example, radio 60 may be implemented on a single integrated circuit. As yet another example, the processing module 50 and the baseband processing module 63 of the host device may be a shared processing device implemented on a single integrated circuit. Further, the memories 52 and 65 may be implemented on a single integrated circuit and/or on an integrated circuit shared by the processing module 50 and the baseband processing module 63 of the host device.

FIG. 4 is a block schematic diagram of an embodiment of a radio frequency transmitter 67 , 69 , 71 . The radio frequency transmitter includes a digital filtering and up-sampling module 475 , a digital-to-analog conversion module 477 , an analog filter 479 , an up-conversion module 481 , a power amplifier 483 and a radio frequency filter 485 . The digital filtering and upsampling module 475 receives a character string from the outbound character string 89 , digitally filters it, and then upsamples the string rate to a desired rate, thereby producing filtered characters 487 . The digital-to-analog conversion module 477 converts the filtered character 487 into an analog signal 489 . An analog signal can include in-phase and quadrature components.

Analog filter 479 filters analog signal 489 to produce filtered analog signal 491 . The frequency up conversion module 481 (which may include a pair of mixers and a filter) mixes the filtered analog signal 491 with a local oscillator 493 generated by the local oscillator module 99 to generate a high frequency signal 495 . The frequency of the high frequency signal 495 corresponds to the frequency of the radio frequency signal 91 .

The power amplifier 483 amplifies the high frequency signal 495 to produce an amplified high frequency signal 497 . An RF filter 485 , which may be a high band pass filter, filters the amplified high frequency signal 497 to produce the desired outbound RF signal 91 .

As is known to those of ordinary skill in the art, each RF transmitter 67, 69, 71 includes a similar structure as shown in FIG. 4 and also includes a closing mechanism so that when a particular RF transmitter is not needed, Disable it in a way that does not generate interfering signals and/or noise.

FIG. 5 is a block schematic diagram of a radio frequency receiver 75 , 77 , 79 . In this embodiment, each radio frequency receiver includes a radio frequency filter 501, a low noise amplifier (LNA) 503, a programmable gain amplifier (PGA) 505, a frequency down conversion module 507, an analog filter 509, and an analog-to-digital conversion module 511 And digital filtering and down-sampling module 513. RF filter 501 (which may be a high band pass filter) receives and filters inbound RF signal 93 to produce a filtered inbound RF signal. The low noise amplifier 503 amplifies the filtered inbound RF signal 93 based on a set gain and provides the amplified signal to the programmable gain amplifier 505 . The programmable gain amplifier further amplifies the inbound radio frequency signal 93 before providing it to the down conversion module 507 .

The frequency down conversion module 507 includes a pair of mixers, a summing module and a filter to mix the incoming radio frequency signal with the local oscillator generated by the local oscillator module to generate an analog baseband signal. The analog filter 509 filters the analog baseband signal and provides it to the analog-to-digital conversion module 511 . The analog-to-digital conversion module 511 converts the analog baseband signal into a digital signal. The digital filter and downsampling module 513 filters the digital signal and then adjusts the sampling rate to generate the inbound string 95 .

Figure 6 is a schematic block diagram of wireless communication devices 25, 27 and/or 29 in communication with access points 12-16. The wireless communication devices 25, 27 and/or 29 may be any of the devices 18-32 shown in Figures 1-3. In FIG. 6 , the access point 12 - 16 includes a processing module 15 , memory 17 and wireless transceiver 19 . The wireless transceiver 19 may be similar in structure to the wireless transceiver of each wireless communication device, and may include multiple antennas, transmitting paths and receiving paths, for performing multiple wireless communications within a nearby area or a basic service set. Processing module 15 may be a single processing device or a plurality of processing devices. Such processing module 15 may be a single microprocessor, microcontroller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuit, analog circuit, Digital circuits and/or any device that manipulates signals (analog and/or digital) based on operational instructions. Memory 17 may be a single memory device or multiple memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. It should be noted that when the processing module 15 performs one or more functions through a state machine, analog circuit, digital circuit and/or logic circuit, the memory storing the corresponding operation instructions is embedded in or externally connected to the state machine, analog circuit , digital circuits and/or logic circuits on circuits. The memory 17 stores and the processing module 15 executes an operation instruction, and the operation instruction corresponds to at least a part of the steps and/or functions shown in FIGS. 7 to 32 .

In FIG. 6, each wireless communication device 25, 27 and 29 uses a different wireless communication protocol. As shown in the figure, the wireless communication device 25 adopts protocol A, the wireless communication device 27 adopts protocol B, and the wireless communication device 29 adopts protocol C. . For example, protocols A, B and C may correspond to different versions of the IEEE 802.11 standard. In particular, protocol A may correspond to IEEE802.11b, protocol B may correspond to IEEE802.11g and protocol C may correspond to IEEE802.11n.

Protocols can be sorted by a protocol sequence table that lists protocols A, B, and C in sequence. The sorting can be performed according to the legacy version of each corresponding protocol, the protocol ranked first is the oldest version, and the protocol ranked last is the latest standard. For example, in the current illustration, Protocol A may correspond to IEEE802.11b, Protocol B may correspond to IEEE802.11g and Protocol C may correspond to IEEE802.11n. Alternatively, protocol sequencing may follow user-defined and/or system administrator-defined procedures. For example, if when establishing wireless communication using protocol A, transmission errors reach an unacceptable level (number) due to unrecognized frames, the user can select protocol B format to establish wireless communication. This concept will be described in more detail with reference to the remaining figures.

In operation, the access point 12-16 and/or each wireless communication device telecommunications 25, 27 and 29 determine the protocol employed by each wireless communication device within the vicinity. Again, a nearby area may include a basic service set and/or a nearby basic service set and/or a direct or multi-hop (ad-hoc) network between which wireless communication devices may directly communicate. Once the protocol for each wireless communication device is determined, the access point 12-16 and/or each wireless communication device telecommunication 25, 27 and 29 determines which protocol to use to establish the wireless communication in protocol order. For example, if protocol A corresponds to IEEE802.11b, the communication device will adopt a medium access control layer (MAC) level protection mechanism to establish wireless communication, as will be further described in FIG. 22 . In this way, each wireless communication device will use protocol A to establish wireless communication, so that the legacy device recognizes the establishment of wireless communication and also recognizes the duration of wireless communication, so it does not transmit during this time, thereby avoiding collisions .

Once the wireless communication is established using a protocol selected from the protocol ranking (for example, protocol A), the communication device will use its protocol to transmit data to other parts in the wireless communication. For example, the wireless communication device 25 will adopt protocol A to establish wireless communication and transmit data. The wireless communication device 27 will use protocol A to establish wireless communication, and then use protocol B to complete corresponding data transmission for the wireless communication. Similarly, the wireless communication device 29 will use protocol A to establish wireless communication, and then use protocol C to perform the data transmission part of the wireless communication.

As known by those of ordinary skill in the art, if only wireless communication devices using the same protocol are included in the nearby area, the establishment of wireless communication and data transmission are completed using this protocol. As further known to those of ordinary skill in the art, if there are only two different protocols in the vicinity, the legacy version protocol will be selected as the established protocol.

FIG. 7 shows the wireless communication between two wireless communication devices 100 and 102 in the vicinity, both of which use the same protocol IEEE802.11n. The wireless communication may be direct (ie, from wireless communication device to wireless communication device) or indirect (ie, from wireless communication device to access point to wireless communication device). In this example, wireless communication device 100 is providing frame 104 to wireless communication device 102 . The frame 104 includes a wireless communication setup information field 106 and a data portion 108 . The wireless communication setup information part 106 includes a short training sequence (STS) 157, which may be 8 μs long; a first additional long training sequence (LTS) 159, which may be 8 μs long, and which is one of a plurality of additional long training sequences 161 a; a signal field field 163, which may be 4 μs long. Note that the number of additional long training sequences 159, 161 corresponds to the number of transmit antennas used in MIMO wireless communication.

The data portion of the frame 104 includes a number of data characters 165, 167, 169, each lasting 4 μs. The final data character 169 also includes tail bits and padding bits as required.

FIG. 8 shows the wireless communication between two wireless communication devices 100 and 102 in the vicinity, both of which use the same protocol IEEE802.11n. The wireless communication may be direct (ie, from wireless communication device to wireless communication device) or indirect (ie, from wireless communication device to access point to wireless communication device). In this example, wireless communication device 100 provides multiple frames 104-1, 104-2, 104-N to wireless communication device 102 using multiple antennas #1-#N. Each frame 104 - 1 , 104 - 2 , 104 -N includes a wireless communication setup information field 106 and a data portion 108 . The wireless communication setup information part 106 includes a short training sequence 157, which may be 8 μs long; a first additional long training sequence 159, which may be 8 μs long, and which is one of a plurality of additional long training sequences 161; a signal field Field 163, may be 4 μs long. Note that the number of the additional long training sequences 159, 161 corresponds to the number of transmit antennas used in MIMO wireless communication.

The data portion of the frame 104 includes a number of data characters 165, 167, 169, each lasting 4 μs. The final data character 169 also includes tail bits and padding bits as required.

In this example, the preamble (sometimes called "Greenfield") is for when only .11n devices are present. Optionally, preambles can be used on legacy devices (. ). (MAC-level protection can also be used to protect very long bursts when legacy stations are not present)

For transmit antenna 1, the short training sequence 157 may be the same as 802.11a. For antennas 2 to N, it is a cyclically shifted version of the same sequence. In the preferred mode, the number of cyclic shifts (shift) for each antenna is calculated as (number of antennas-1)×800/N ns. That is, the shift is 0 for 1 antenna. For 2 antennas, the shift is 0 ns for antenna 1 and 400 ns. For 3 antennas, the shifts are 0, 250 and 500 ns. For 4 antennas, the shifts are 0, 200, 400 and 600ns, respectively. The implementation is simple when the shift is rounded to 50 ns (the reciprocal of the character clock frequency). Shifting can be performed in a forward or backward direction.

Additional long training sequences 159, 161: (m=1) There are many possible implementations. For this case there will be only one long training sequence 159 . For antenna 1, it will be the same as the 802.11a long training sequence 159, but only 4 μs long, which includes a guard interval of 0.8 μs. For antenna 2-N, it is a cyclically shifted variant of the same sequence. In the preferred mode, the number of cyclic shifts for each antenna is calculated as (number of antennas-1)×4/Nμs. That is, the shift is 0 for 1 antenna. For 2 antennas, the shift is 0 ns for antenna 1 and 4 μs. For 3 antennas, the shifts are 0, 2.65 and 5.35 μs. For 4 antennas, the shifts are 0, 2, 4 and 6 μs. Again, the implementation is simple when the shift is rounded to 50 ns (the reciprocal of the character clock frequency). Shifting can be performed in a forward or backward direction.

For (m=N), the number of training sequences is equal to the number of transmit antennas. The (m=1) case is preferred because it results in less channel estimation error at the receiver, especially for a larger number of antennas. Therefore, it is scalable. There are two possible choices for the training sequence:

Zero Interval - In this case, the sequence (1,1), (2,2), (3,3)... until (N,N) is the same as the 802.11a long training sequence. All others (ie (1,2), (2,1), etc.) are zero signals - no data is transmitted during this time slot.

Subchannel Nulls—In this case, the set of subchannels in the training sequence is subdivided by the number of transmit antennas. A separate subset is activated at each sub-training interval.

The orthogonal sequence is generated by multiplying the subcarrier of the 802.11a long training sequence by an m×m orthonormal matrix (for example, the matrix that generates the discrete Fourier transform).

FIG. 9 is a schematic illustration of the present invention using cyclically shifted preambles for two transmit antenna frames 104-1, 104-2, where the communication device is located in a neighborhood that includes only 802.11n compliant devices. The preamble is part of the wireless communication setup information 106 which includes a short training sequence 157 , long training sequences 159 and 161 , a signal field (SIG1 ) 224 and a data field or other signal field 228 . For the first antenna frame 104-1, the short training sequence 157 is divided into two groups of bursts 232,234. In one embodiment, the short training sequence 157 comprises 10 characters of 800 ns according to an early version of the 802.11x specification. The long training sequences 159 and 161 of the first antenna frame 104-1 include a double guard interval (GI2) 236, which may be 1600 ns in duration and corresponds to the last of the long training sequences pre-programmed for the long training sequences 159 and 161 1600ns.

The long training sequence 159 and 161 of the first antenna frame 104-1 includes a twice repeated long training sequence, which may correspond to an earlier version of the 802.11x specification, wherein the tones of the long training sequence are divided into two groups 238,240. The signal field 224 and an optional second signal field 228 contain information as previously described, which may be separated by a guard interval (GI) 220 , 226 .

The preamble for the second antenna frame 104-2 includes similar components to the first antenna preamble, but the short training sequence 157 and/or the long training sequences 159 and 161 are cyclically shifted. As shown, the second set of characters 234 precedes the first set of characters 232 in time within the short training sequence 157 , which is the opposite of the timing sequence of the antenna 1 preamble. As further shown, the short training sequence 157 may include 10 characters divided into two groups, wherein the first group 232 includes characters 0-5 and the second group 234 includes characters 6-9. For the first antenna, the first group of characters 232 precedes the second group 234 in time; for the second antenna, the second group of characters 234 precedes the first group 232 in time. In one embodiment, the shift of the cycle may be 400-1600 ns.

Each long training sequence frame plane of the long training sequence fields 159 and 161 can be divided into two groups 238, 240 as shown, wherein, for the first antenna frame 104-1, the first group of tones 238 are temporally separated by the second group of tones. group of tones 240; for the second antenna frame 104-2, the second group of tones 240 precedes the first group of tones 238 in time. As such, the long training sequences 159 and 161 of the second antenna frame 104-2 are cyclically shifted representations of the long training sequences 159 and 161 of the first antenna frame 104-1.

FIG. 10 is a schematic diagram of preambles with different forms of cyclic shifting by using loose characters and/or tones for two transmit antenna frames 104-1, 104-2, where the communication device is located only including 802.11n compliant devices the nearby area. The preamble is part of the wireless communication setup information 106, which includes a short training sequence 157, long training sequences 159 and 161, a signal field (SIG1) 224, a data field or other signal field 228 and two guard intervals (GI) 220, 226. In this embodiment, the characters of the short training sequence 157 are divided into two groups of characters 232,234. The first set 232 is included in the first antenna frame 104-1 and the second set of characters 234 is included in the second antenna frame 104-2. The figure includes an example of splitting characters into two groups 232, 234, where, in one embodiment, the short training sequence 157 includes 10 characters according to an early version of the 802.11x specification. The long training sequences 159 and 161 of the first antenna frame 104-1 include a double guard interval (GI2) 236, which may be 1600 ns in duration and corresponds to the last of the long training sequences pre-programmed for the long training sequences 159 and 161 1600ns.

Long training sequences 159 and 161 include two repetitions of long training sequences, which may be compliant with earlier versions of the 802.11x specification. Therein, the tones of the long training sequence are divided into two groups 238,240. A first set of tones 238 is included in the first antenna frame 104-1 and a second set of tones 240 is included in the second antenna frame 104-2.

11 is a schematic diagram of preambles using cyclic shifts for three transmit antenna frames 104-1, -2, -3, where the communication device is located in a neighborhood that includes only 802.11n compliant devices. The preamble is part of the wireless communication setup information 106, which includes a short training sequence 157, a long training sequence (LTS) 159 and 161, a signal field (SIG1) 224, a data field or other signal field 228, and two guard intervals ( GI) 220, 226. For the first antenna frame 104-1, the short training sequence is divided into three groups of characters 250,252,254. In one embodiment, the short training sequence 157 includes 10 characters of 800 ns according to an early version of the 802.11x specification, where, for example, the first set of characters 250 includes 0-2, the second set of characters 252 includes 3-5, the second set of characters 252 includes Three groups of characters 254 include 6-9. Other groupings of characters may also be used, as known to those of ordinary skill in the art.

The long training sequences 159 and 161 of the first antenna frame 104-1 include a double guard interval (GI2) 236, which may be 1600 ns in duration and corresponds to the last of the long training sequences pre-programmed for the long training sequences 159 and 161 1600ns. The long training sequences 159 and 161 include two repeated long training sequences, which may comply with earlier versions of the 802.11x specification. Therein, the tones of the long training sequence are divided into three groups 256, 258, 260. The signal field 224 and optional second signal field 238 contain information as previously described.

The preambles of the second and third antenna frames 104-2, 104-3 contain similar components to the preambles of the first antenna frame 104-1, but with short training sequences 157 and/or long training sequences Sequences 159 and 161 are cyclically shifted. As shown, the three sets of characters 250, 252, 254 are shifted in time relative to each antenna frame 104-1, 104-2, 104-3. In one embodiment, the cyclic shift may be 400-1600 ns.

Each of the long training sequence frames of the long training sequence fields 159 and 161 can be divided into three groups 256, 258, 260 as shown, wherein, for the first antenna frame 104-1, the first group of tones 256 is temporally Before the second and third sets of tones 258, 260; for the second antenna frame 104-2, the second set of tones 258 is in time before the first and third sets of tones 256, 260; for the third antenna frame 104-2 3. The third set of tones 260 precedes the first and second sets of tones 256, 258 in time. As such, the long training sequences 159 and 161 of the second and third antenna frames 104-2, 104-3 are cyclically shifted representations of the long training sequences 159 and 161 of the first antenna frame 104-1.

FIG. 12 is a schematic diagram of an alternative preamble comprising a legacy portion and an additional portion using cyclic shifts for three transmit antenna frames 104-1,-2,-3. The legacy part includes the short training sequence 157 and the long training sequences 159 and 161 . The short training sequence 157 can be divided into three groups of characters 250,252,254; the long training sequences 159 and 161 can be divided into two groups of tones 238,240. The additional portion includes a guard interval 274 and a single long training sequence frame comprising the first and second sets of tones 276,278.

In this embodiment, s1..s2 are K×200 ns cyclic shifts of s0, where K=1..2, s0-s2 correspond to respective antenna frames 104-1, 104-2, 104-3 The short training sequence field is 157 characters. The first and second sets of tones 238, 240 of the long training sequences 159 and 161 correspond to two legacy version 802.11a long training characters (3.2 μs each plus a 1.6 μs pre-planned double guard interval GI 2236), where each This is the same for the first and second sets of tones 238,240. The first and second sets of tones 238, 240 of the long training sequences 159 and 161 of the second antenna frame 104-2 are 1.6 each of the first and second sets of tones 238, 240 of the first antenna frame 104-1. Cyclic shift in μs. The additional long training sequence of the third antenna frame 104-3 is a copy of the first and second set of tones 238, 240 of one long training sequence frame plane of the first antenna frame 104-1 plus a pre-planned double guard interval 274 ( last 1.6µs). Only the first data character (Data 0) 272 has a pre-planned double guard interval 270 (last 1.6 μs). All subsequent data characters have only a pre-planned guard interval (GI) (the last 800ns). The double guard interval field 274 before the additional long training sequence and the double guard interval field 270 before the first data character (data 0) are used to allow setting of the power amplifier.

13 is a schematic diagram of a preamble comprising loose characters and/or tones in a cyclically shifted form for three transmit antenna frames 104-1, 104-2, 104-3 where the communication device is located only n the vicinity of the device. The preamble is part of the wireless communication setup information 106, which includes a short training sequence 157, long training sequences 159 and 161, a signal field (SIG1) 224, a data field or other signal field 228 and two guard intervals 220,226. In this embodiment, the characters of the short training sequence 157 are divided into three groups 280,282,284. The first group 280 is included in the first antenna frame 104-1; the second group of characters 282 is included in the second antenna frame 104-2; and the third group of characters 284 is included in the third antenna frame 104-3. Also included in the figure is an example of grouping characters where, in one embodiment, the short training sequence 157 includes 10 characters according to an early version of the 802.11x specification. In such an example, the first set 280 may include characters 0,3,6, the second set 282 may include characters 1,4,7, and the third set 284 may include characters 2,5,8.

The long training sequences 159 and 161 of the first antenna frame 104-1 include a double guard interval (GI2) 236, which may be 1600 ns in duration and corresponds to the last 1600 ns of the long training sequence pre-programmed for the long training sequence 161 . The long training sequence consists of a two-repetition long training sequence 159 and 161 , which may comply with earlier versions of the 802.11x specification, wherein the tones of the long training sequence are divided into three groups 286 , 288 , 290 . A first set of tones 286 is included in the first antenna frame 104-1; a second set of tones 288 is included in the second antenna frame 104-2; and a third set of tones 290 is included in the third antenna frame 104-3. For example, if a long training sequence includes 15 tones, the first set 286 may include tones 0, 3, 6, 9, 12; the second set 288 may include tones 1, 4, 7, 10, 13; the third set 290 Tones 2, 5, 8, 11, 14 may be included.

14 is a schematic diagram of four transmit antenna frames 104-1, 104-2, 104-3, 104-4 using cyclically shifted preambles. As shown, the short training sequence 157 may be divided into four groups of characters 300, 302, 304, 306 and/or the long training sequences 159 and 161 may be divided into four groups of tones 308, 310, 312, 314. For each antenna frame 104-1, 104-2, 104-3, 104-4, the group of characters 300, 302, 304, 306 is cyclically shifted, and/or the group of tones 308, 310, 312, 314 is cyclically shifted bit.

Figure 15 is another illustration of the preambles for four transmit antenna frames 104-1, 104-2, 104-3, 104-4 using cyclic shifting. In this embodiment, s1..s3 is a K×200 ns cyclic shift of s0, where K=1..3, s0-s3 corresponds to the bursts 300, 302, 304, 304, 306. The long training sequences 159 and 161 and the signal field 224 of the first and second antenna frames 104-1, 104-2 are the same as discussed with reference to FIG. 12 . The additional long training sequence of the third antenna frame 104-3 includes a first set 238 and a second set 240, which may be the first and second sets of tones 238 of the long training sequences 159 and 161 of the first antenna frame 104-1 , 240 replications, plus a pre-planned double guard interval (GI2) 236 (last 1.6 μs). The additional long training sequence for the fourth antenna frame 104-4 includes the first and second sets of tones 238, 240 of the long training sequence for the second antenna frame 104-2, plus a pre-planned double guard interval (GI2) 236 ( last 1.6µs). In other words, the long training sequence of the fourth antenna frame 104-4 is a 1.6 μs cyclic shift of the additional long training sequence of the third antenna. The first data character (Data 0) 272 has a pre-planned double guard interval (GI2) 270 (last 1.6 μs). All subsequent data characters have only a pre-planned guard interval (GI) (the last 800ns).

16 is a schematic diagram of a preamble using loose characters and/or tones for a frame with cyclic shifts for four transmit antennas, where the communication device is located in a neighborhood that includes only 802.11n compliant devices. The preamble is part of the wireless communication setup information 106, which includes a short training sequence 157, long training sequences 159 and 161, a signal field (SIG1) 224, a data field or other signal field 228 and two guard intervals 220,226. In this embodiment, the characters of the short training sequence 157 are divided into four groups 320, 322, 324, 326. The first group of characters 320 is included in the first antenna frame 104-1; the second group of characters 322 is included in the second antenna frame 104-2; the third group of characters 324 is included in the third antenna frame 104-3; Group character 326 is included in fourth antenna frame 104-4. The figure includes an example of grouping characters, where, in one embodiment, the short training sequence 157 includes 10 characters according to an earlier version of the 802.11x specification. For example, a first set of characters 320 may include characters 0,4, a second set of characters 322 may include characters 1,5, a third set of characters 324 may include characters 2,6, and a fourth set of characters 326 may include characters 3,7.

The long training sequences 159 and 161 of the first antenna frame 104-1 include a double guard interval (GI2) 236, which may be 1600 ns in duration and corresponds to the last 1600 ns of the long training sequence pre-programmed for the long training sequence. The long training sequence includes two repeated long training sequences 159 and 161, which may be compliant with earlier versions of the 802.11x specification. Therein, the tones of the long training sequence are divided into four groups 328, 330, 332, 334. The first set of tones 328 is contained in the first antenna frame 104-1; the second set of tones 330 is contained in the second antenna frame 104-2; the third set of tones 332 is contained in the third antenna frame 104-3; A fourth set of tones 334 is included in the fourth antenna frame 104-4. For example, if the long training sequence includes 20 tones, the first set 328 may include tones 0, 4, 8, 12, 16; the second set 330 may include tones 1, 5, 9, 13, 17; the third set 332 may include Tones 2, 6, 10, 14, 18 are included; the fourth set 334 may include tones 3, 7, 11, 15, 19. Note that the additional long training sequence field can be used so that the tones of the long training sequence frame are divided into only two groups of tones.

Fig. 17 is a schematic diagram of wireless communication between two wireless communication devices 100 and 102, both of which comply with IEEE802.11n. The communication occurs in a vicinity that includes an 802.11n-compliant device, an 802.11a-compliant device, and/or an 802.11g-compliant device. In this example, the wireless communication may be direct or indirect, where frame 110 includes legacy portion 112 of setup information, remainder of setup information 114 and data portion 108 .

The legacy portion 112 of the setup information includes a short training sequence 157 lasting 8 μs, a long training sequence 171 lasting 8 μs and a signal field 173 lasting 4 μs. The signal field 173 includes a number of bits to indicate the duration of the frame 110, as is known. In this way, 802.11a-compliant devices in the vicinity and 802.11g-compliant devices in the vicinity will be able to recognize that a frame is being transmitted even if such devices cannot decode the rest of the frame. In this example, based on proper decoding of the legacy portion 112 of the wireless communication setup message, legacy version devices (IEEE802.11a and IEEE802.11g) will avoid conflicts with IEEE802.11n communications.

The remaining setup information 114 includes additional long training sequences 159, 161, each lasting 4 μs. The remaining setup information also includes a high data signal field 163 for 4 μs to provide additional information about the frame. Data portion 108 includes data characters 165, 167, 169, all 4 μs in duration, as previously described with reference to FIG. 7 . In this example, the legacy part is provided at the physical layer.

Fig. 18 is a schematic diagram of wireless communication between two wireless communication devices 100 and 102, both of which comply with IEEE802.11n. The communication occurs in a vicinity that includes an 802.11n-compliant device, an 802.11a-compliant device, and/or an 802.11g-compliant device. In this example, the wireless communication can be direct or indirect, where multiple antennas are employed, and the frames 110-1, 110-2, 110-N include the legacy portion 112 of the setup information, the remainder of the setup information 114 and the data portion 108.

The legacy portion 112 of the setup information includes a short training sequence 157 lasting 8 μs, a long training sequence 171 lasting 8 μs and a signal field 173 lasting 4 μs. The signal field 173 includes a number of bits to indicate the duration of the frame 110, as is known. In this way, 802.11a-compliant devices in the vicinity and 802.11g-compliant devices in the vicinity will be able to recognize that a frame is being transmitted even if such devices cannot decode the rest of the frame. In this example, based on proper decoding of the legacy portion 112 of the wireless communication setup message, legacy version devices (IEEE802.11a and IEEE802.11g) will avoid conflicts with IEEE802.11n communications.

The remaining setup information 114 includes additional long training sequences 159, 161, each lasting 4 μs. The remaining setup information also includes a high data signal field 163 for 4 μs to provide additional information about the frame. Data portion 108 includes data characters 165, 167, 169, all 4 μs in duration, as previously described with reference to FIG. 7 . In this example, the legacy part is provided at the physical layer.

In one embodiment, m is the number of long training sequences per frame, N is the number of transmit antennas, and the preamble (sometimes referred to as "Brownfield") is for IEEE802.11a or .11g legacy devices The situation that exists. For transmit antenna 1, the short training and long training sequences are the same as 802.11a. For antennas 2 to N, there are two possibilities:

A cyclically shifted version of the same sequence. For short training, the number of cyclic shifts for each antenna is calculated as (number of antennas-1)×800/N ns; for long training, the number of cyclic shifts for each antenna is calculated as (number of antennas-1)×4/N μs calculate.

The second mode is a short training null signal transmitted on antennas 2 to N through the signal field portion (ie during this time interval these antennas do not transmit). Also, the additional long training sequence for antenna 1 is not used and no data is transmitted during this time period.

The signal field 173 will follow the same format as 802.11a, except that the reserved bit (4) will be set to 1 to indicate an 802.11n frame and subsequent training for the .11n receiver. This additional long training sequence can be defined in various ways:

(m=1) For this case there will be only one additional long training sequence 159, which will be orthogonal to the 802.11a long training sequence.

(m=N) For this case, the number of training sequences is equal to the number of transmit antennas. The (m=1) case is preferred because it results in less channel estimation error at the receiver, especially for a larger number of antennas. Therefore, it is scalable.

There are two possible choices for the training sequence:

Zero Interval—In this case, the sequence (1,1), (2,2), (3,3)... until (m,m) is the same as the 802.11a long training sequence. All others (ie (1,2), (2,1), etc.) are zero signals - no data is transmitted during this time slot.

Subchannel Nulls—In this case, the set of subchannels in the training sequence is subdivided by the number of transmit antennas. A separate subset is activated at each sub-training interval.

An embodiment using an orthogonal sequence, which is generated by multiplying the 802.11a long training sequence by an m×m orthogonal matrix (such as the matrix that generates the discrete Fourier transform), will be described in more detail with reference to FIGS. 29-32 description of. For example, the case of 4 antennas would use the following orthogonal matrix to generate subcarriers for each additional long training sequence.

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="10"\; label="s"\; filenames="A200510070136.000641.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="11"\; label="s"\; filenames="A200510070136.000951.png,A200510070136.000981.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="12"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="20"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 20</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="30"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 30</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="31"\; label="s"\; filenames="A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 31</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="32"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 32</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; k</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}\\ {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>}\\ {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}\end{array}\right]$

θ _k = π·k/(4·N _subcarriers )

φ _k ＝π·(k+4)/(2·N _subcarriers )

FIG. 19 is a schematic diagram of preambles for frames 104-1, 104-2 using a cyclic shift for two transmit antennas using a legacy portion. As shown, the short training sequence 157 is divided into two groups of characters 344,346. For example, first group 344 may include characters 0-4; second group 346 may include characters 5-9. The next part of the preamble of the first antenna frame 104 - 1 includes a legacy long training sequence 340 , guard interval 220 and a signal field 224 . The additional long training sequence 342 of the second antenna frame 104-2 is the same as the long training sequence of the first antenna frame, but shifted in time.

20 is a schematic diagram of preambles for frames 104-1, 104-2, 104-3 using a cyclic shift for three transmit antennas using a legacy portion. As shown and as previously discussed, the short training sequence 157 is divided into three groups of characters 250,252,254. The next part of the preamble of the first antenna frame 104 - 1 includes a legacy long training sequence 340 , guard interval 220 and signal field 224 . The additional long training sequence 342 of the second antenna frame 104-2 is the same as the long training sequence of the first antenna frame, but shifted in time. The additional long training sequence of the third antenna frame 104-3 is a cyclically shifted variant of the additional long training sequence of the second antenna. All three frames 104 - 1 , 104 - 2 , 104 - 3 also include a double guard interval 336 and a data field 228 .

21 is a schematic diagram of preambles for frames 104-1, 104-2, 104-3, 104-4 using a cyclic shift using the four transmit antennas of the legacy portion. As shown and as previously discussed, the short training sequence 157 is divided into four groups of character strings 300, 302, 304, 306. The next part of the preamble of the first antenna frame 104 - 1 includes a legacy long training sequence 340 , guard interval 220 and a signal field 224 . The additional long training sequence 342-1 of the second antenna frame 104-2 is the same as the long training sequence of the first antenna frame 104-1, but shifted in time. The additional long training sequence 342-2 of the third antenna frame 104-3 is a cyclically shifted variant of the additional long training sequence of the second antenna frame 104-2. The additional long training sequence 342-3 of the fourth antenna frame 104-4 includes only one long training sequence frame plane 264 of the legacy long training sequence, which is shifted in time as shown and lasts approximately 4 μs.

Fig. 22 is a schematic diagram of wireless communication between two wireless communication devices 100 and 102, both of which comply with IEEE802.11n. The communication may be direct or indirect wireless communication within a vicinity that includes an 802.11 compliant device, an 802.11a compliant device, an 802.11b compliant device, and/or an 802.11g compliant device. In this example, frame 110 includes legacy portion 112 of setup information, remainder of setup information 114 and data portion 108 . As shown, the legacy portion 112 of the setup message, or legacy frame, includes an IEEE 802.11 physical layer (PHY) preamble (ie, short training sequence, long training sequence, and signal field) and a medium access control (MAC ) to split the frame part. The medium access control (MAC) segmented frame portion indicates a specific portion of a specific frame that can be deciphered by a legacy device. In this example, the legacy protection is provided at the media access control layer.

The remaining setup information 114 includes a number of additional long training sequence and high data signal fields. The data portion 108 includes a plurality of data characters as previously described.

Fig. 22 is a schematic diagram of wireless communication between two wireless communication devices 100 and 102, both of which comply with IEEE802.11n. The communication may be direct or indirect wireless communication within a vicinity that includes an 802.11 compliant device, an 802.11a compliant device, an 802.11b compliant device, and/or an 802.11g compliant device. In this example, frame 110 includes legacy portion 112 of setup information, remainder of setup information 114 and data portion 108 . As shown, the legacy portion 112 of the setup message, or legacy frame, includes an IEEE 802.11 physical layer (PHY) preamble (i.e., short training sequence 157, long training sequence 171, and signal field 173 and a medium access control (MAC) Segmented Frame Section 175. The Media Access Control (MAC) Segmented Frame Section indicates a particular portion of a particular frame that can be deciphered by a legacy device. In this example, the legacy protection is provided at the Media Access Control layer.

The remaining setup information 114 includes a number of additional long training sequences 159 , 161 and a high data signal field 163 . The data portion 108 includes a plurality of data characters 165, 167, 169 as previously described.

FIG. 23 is a schematic diagram of wireless communication between two wireless communication devices 100 and 102. Both wireless communication devices 100 and 102 comply with IEEE802.11n and adopt multiple antennas. The communication may be direct or indirect wireless communication within a vicinity that includes an 802.11 compliant device, an 802.11a compliant device, an 802.11b compliant device, and/or an 802.11g compliant device. In this example, each frame 111 - 1 , 111 - 2 , 111 -N includes a legacy portion 112 of setup information, a remainder of setup information 114 and a data portion 108 . As shown, the legacy portion 112 of the setup information, or legacy frame, includes an IEEE 802.11 physical layer (PHY) preamble (ie, short training sequence 157, long training sequence 171, and signal field 173) and a medium access The control (MAC) divides the frame portion 175 . The medium access control (MAC) segmented frame portion indicates a specific portion of a specific frame that can be deciphered by a legacy device. In this example, the legacy protection is provided at the media access control layer. Note that, except for the signal field, these fields follow the same structure as previously described in FIG. 9 and FIG. 10 . This is an alternative method using MAC segmentation to set the Network Allocation Vector (NAV) of the legacy station. The MAC layer segment contains frame information encoded at the legacy code rate to allow reception by .11a and .11g stations. The definition of the additional long training sequences 159 and 161 follows the same format as that shown in FIG. 9 above.

The remaining setup information 114 includes a number of additional long training sequences 159 , 161 and a high data signal field 163 . The data portion 108 includes a plurality of data characters 165, 167, 169 as previously described.

Figure 24 illustrates a method for multi-protocol wireless communication within a wireless local area network (WLAN). The method begins at step 120, where an access point (for indirect wireless communication) or a wireless communication device (for direct wireless communication) determines the protocols of the wireless communication devices within the vicinity. In one embodiment, the protocol adopted by each wireless communication device may be determined according to the frequency band used by each wireless communication device and the communication format of the wireless local area network. For example, if the frequency band is 2.4GHz, the device may have a wireless LAN communication format conforming to IEEE802.11b, IEEE802.11g, and/or IEEE802.11n. If the frequency band is 4.9-5.85GHz, the device may have a WLAN communication format conforming to IEEE802.11a or IEEE802.11n. Further, the nearby area includes a coverage area of a basic service set, a coverage area of a multi-hop (ad-hoc) network, and/or a coverage area of at least a part of the basic service set and at least one adjacent basic service set (BSS) . As shown in FIG. 1 , the adjacent basic service sets (BSS) of the access point 12 include the BSS of the access point 14 and/or the BSS of the access point 16 .

Returning to Fig. 24, the next step of the method is step 122, wherein the access point and/or the wireless communication device determines whether the protocols of the wireless communication devices in the nearby area belong to the same protocol. Next step 124 of the method, wherein, according to the determination result of whether the protocols of the wireless communication devices in the nearby area belong to the same protocol, the method branches. When all the wireless communication devices in the vicinity adopt the same protocol, the method continues to step 126, wherein the wireless communication devices use the same protocol to establish wireless communication and perform wireless communication.

However, if at least one wireless communication device has a different protocol, the method continues to step 128, wherein the access point or wireless communication device selects a protocol among the protocols of the wireless communication devices in the vicinity according to protocol ordering, thereby Generate a selected protocol. The protocol sorting can be performed according to the legacy version sorting of the wireless communication devices and/or the protocol sorting can be performed according to the protocol transmission efficiency sorting. For example, devices conforming to IEEE802.11, IEEE802.11b, IEEE802.11g and IEEE802.11n work in the 2.4GHz frequency band, and devices conforming to IEEE802.11a and IEEE802.11n work in the 4.9-5.85GHz frequency band. Therefore, in the 2.4GHz frequency band, if an 802.11b station and an 802.11n device coexist, the protection mechanism of the medium access control layer as defined in 802.11g can be adopted, as shown in FIG. 6 . However, if only 802.11g legacy devices coexist with 802.11n devices, either the media access control layer (eg, Figure 6) or the physical layer (PHY) (eg, Figure 5) protection mechanism can be used. In the 4.9-5.85GHz frequency band, if 802.11a equipment and 802.11n equipment coexist, media access control layer or physical layer protection mechanism can be used.

As is known to those of ordinary skill in the art, of the two protection mechanisms, the physical layer and the media access control layer, the former is more desirable because throughput collisions are reduced since additional frames for MAC layer protection are not required. Therefore, where possible, physical layer protection mechanisms should be used first. If the physical layer mechanism does not work well, the MAC layer mechanism should be used when it detects that the number of unanswered frames exceeds the limit value.

As known to those of ordinary skill in the art, legacy status and need to employ protection mechanisms can be activated in the ERP information component of a beacon frame (or probe response frame). Typically, 802.11g uses bit 0 to indicate the presence of non-ERP (i.e. .11b) and bit 1 to force stations to use protection (MAC layer). This may be extended to use reserved bits (3 to 7) to indicate. Legacy status for 11g or .11a stations. In one embodiment, bit 3 may be used to indicate "presence of legacy Orthogonal Frequency Division Multiplexing (OFDM)". This bit is explained below. Bit 0 - Presence of non-ERP Bit 1 - Adoption Protection Bit 3 - Presence of legacy OFDM 802.11n action 0 0 0 Using .11n frame 1 1 0 Protected by MAC 1 1 1 Protected by MAC 0 1 1 Using PHY and MAC protection 0 0 1 Optionally employs PHY or MAC protection

The Media Access Control layer (MAC) protection mechanism for .11n is the same as for .11g. A station shall set the network allocation vector (NAV) of the legacy station using either a clear to send (CTS to self) or a clear to send/send request exchange.

Returning to FIG. 24 , the method continues at step 130 , where the wireless communication device employs the selected neighborhood protocol to establish neighborhood wireless communication. This is illustrated in the previous figure. The method then continues to step 132, where the wireless communication device transmits data for the wireless communication using its own protocol.

Figure 25 is a logic diagram of a method of determining whether a selected protocol should be changed. The method begins at step 140, where the access point and/or wireless communication device monitors data transmissions within a nearby area for unanswered data transmissions. The method continues at step 142, where the access point and/or wireless communication device compares unanswered data transmissions to a threshold of transmission failures (eg, at most 5%). If the comparison is satisfactory, then proceed to step 146, the selected protocol remains unchanged, and step 140 is repeated.

However, if the comparison result of step 144 is unsatisfactory, the method continues to step 148, and the access point and/or the wireless communication device selects a protocol among the protocols of a plurality of wireless communication devices in the nearby area according to the protocol ranking to generate Another selected protocol. For example, when too many transmission errors are generated, the protection mechanism of the medium access control layer can be used to replace the protection mechanism of the physical layer. The method continues at step 150 where the wireless communication device establishes wireless communication within the vicinity using another selected protocol within the vicinity.

26 is a logic diagram of a method for a wireless communication device to participate in multi-protocol wireless communication. The method starts at step 160, where the wireless communication device contacts an access point using its own protocol (eg, IEEE802.11n). The method then continues to step 162, where the wireless communication device receives the selected protocol from the access point. Note that the selected protocol and the protocol of the wireless communication device may be WLAN communication conforming to IEEE802.11, IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11n and/or further versions of IEEE802.11 Format. Note further that the selected protocol includes a first frame format with a legacy header and a media access control layer segmentation field, a second frame format with a physical layer backward compatible header, and/or a current version header and The third frame format of the Media Access Control Layer Segmentation field.

The method then continues to step 164, wherein the wireless communication device determines whether the selected protocol and the protocol of the wireless communication device belong to the same protocol. The method branches at step 166, from step 166 to step 168 when the protocols are the same; from step 166 to step 170 if the protocols are different. In step 168, the wireless communication device establishes wireless communication and transmits data using the protocol. In step 170, the wireless communication device establishes wireless communication using the selected protocol. The method then continues to step 172, where the wireless communication device communicates wirelessly using its own protocol.

27 is a logic diagram of a method for a wireless communication device to participate in multi-protocol wireless communication. The method begins at step 180, wherein the wireless communication device receives a frame over a wireless channel. The method then continues to step 182, wherein the wireless communication device determines whether the selected protocol belongs to the same protocol as the wireless communication device. When the selected protocol is the same as that of the wireless communication device, the method continues at step 184, where the wireless communication device establishes wireless communication and transmits data using its own protocol.

However, if the selected protocol is not the same as that of the wireless communication device, the method continues at step 186, wherein the wireless communication device decodes at least one of the wireless communication setup information portions of the frame using the selected protocol. part. In one embodiment, the wireless communication device may provide decoding of at least a portion of the wireless communication setup information by decoding to verify whether the header of the frame is consistent with a legacy physical layer format, to decode the setup information; when When the header of the frame is inconsistent with the legacy physical layer format, it is determined whether the rest of the frame is formatted according to the protocol of the wireless communication device. Note that the legacy physical layer format includes at least one of IEEE802.11a and IEEE802.11g, wherein the protocol of the wireless communication device includes IEEE802.11n.

In another embodiment, the wireless communication device may provide decoding of at least a portion of the wireless communication setup information by decoding to verify whether the frame conforms to a legacy medium access control layer format, to decode the setup information; When the header of the frame is inconsistent with the format of the legacy MAC layer, it is determined whether the rest of the frame is formatted according to the protocol of the wireless communication device. Note that the legacy MAC layer format includes at least one of IEEE802.11a, IEEE802.11b and IEEE802.11g, wherein the protocol of the wireless communication device includes IEEE802.11n.

The method then continues at step 188, wherein the wireless communication device, based on decoding of at least a portion of the wireless communication setup information, determines whether the remainder of the frame is formatted according to the wireless communication device's protocol. When the remaining part of the frame is formatted according to the protocol of the wireless communication device, the method branches to step 194 from step 190; when the remaining part of the frame is not formatted according to the protocol of the wireless communication device, the method proceeds from step 190 Branch to step 192. In step 192, the wireless communication device ignores the frame. In step 194, the wireless communication device processes the remainder of the frame according to the protocol of the wireless communication device.

28 is a logic diagram of a method for a wireless communication device to participate in multi-protocol wireless communication. The method begins at step 200, wherein the wireless communication device determines whether the selected protocol belongs to the same protocol as the wireless communication device. When the selected protocol is the same protocol as the wireless communication device's protocol, the method branches from step 202 to step 204; when the selected protocol is not the same protocol as the wireless communication device's protocol, the method Branch from step 202 to step 206 . In step 204, the wireless communication device formats the setup information part and the data part of the frame according to its own protocol. The wireless communication device then transmits the frame.

However, if the selected protocol is not the same as that of the wireless communication device, the method continues at step 206, wherein the wireless communication device formats a portion of the wireless communication setup information in accordance with the selected protocol to produce a legacy format of the build information. The method then continues with step 208, wherein the wireless communication device formats the remainder of the wireless communication setup message in accordance with the wireless communication device's protocol to produce a currently formatted setup message. The method then continues to step 210, wherein the wireless communication device formats the data according to the wireless communication device's protocol to produce currently formatted data. See the previous illustrations for examples of these formats. The method then continues to step 212, where the wireless communication device transmits a frame containing legacy format setup information, current format setup information, and current format data.

In one embodiment of the invention, the preamble should be backward compatible with existing 802.11 standards. One of the issues of IEEE802.11 Task Group N (Task Group N, TGn) is how to interoperate with devices of legacy versions 802.11a and 802.11b/g, where the interoperability includes two situations:

- Same Basic Service Set (BSS): All devices communicate with the same AP.

A co-channel/"overlapping" Basic Service Set (BSS) allows 802.11a/g STAs to de-assert CCA by designing the PLCP header, or by using a Request to Send/Clear to Send( RTS/CTS) or clear-to-send (CTS-to-self) protection mechanism.

- 802.11g opts for the latter when it comes to 802.11b devices.

- To some extent, however, request-to-send/clear-to-send can be relied upon to protect bursts.

For decoding of unchanged signal fields at legacy stations, at the transmit antenna input, it is desirable to employ the same linear weighting as existing long training and signal symbols. For multiple-input-single-out (MISO) systems, the same weighting will be applied to the first two long training characters and the legacy signal field when decoding by the legacy station.

For the case of M transmitter antennas, N receiver antennas, and a sequence of L transmitted symbols, the signal received on subcarrier k is Xk:

If the long training character sequence has been defined (i.e. Sk ends with a real scalar multiplied by a unary matrix), the zero forcing (ZF) MIMO channel estimation can be calculated by:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}$

The minimum mean square error (MMSE) channel estimate can be calculated by:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}$

$\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Wherein, for the sake of simplicity, it is assumed that hk is an independent, identically distributed (iid) of Gaussian type, and the "good long training choice" (good long training choice) is used again. Note that the estimation of the performance of the smallest mean squared error against zero forcing can be neglected for the latter chosen sequence, since S is chosen carefully, as shown before.

FIG. 29 and FIG. 30 are schematic diagrams of the transmission model of the frame format shown in FIG. 7 . For this transmission mode, W is chosen such that both W and W ^-1 are easily achievable in order to ensure backward compatibility issues and meet the needs of the next generation channel estimation requirements. Further, any beamforming from MIMO transmitters (next generation devices), via [w11...w1M] processing, will be well received by legacy 802.11a/g devices.

In this embodiment, channel sounding (S _k ) 253 is multiplied by a number of weighted factors (W _k,m ) 301, 303, 305, where k corresponds to a channel sounding number ranging from 1 to 1, m corresponds to the number of transmission antennas 81-85. The resulting weighted channel sounding is converted into radio frequency signals via transmitters 67 , 69 , 71 and subsequently transmitted via antennas 81 , 83 , 85 . In this embodiment, a weighting factor matrix can be as follows:

Nulls may form when there are signals transmitting on all antennas at all times. The null can be compensated by choosing a weighted sequence as a beamformer such that the null travels in some particular direction. For example, for the case of vector w1=[1,1] (a row of the aforementioned slide's W matrix for the case of 2 transmit antennas), the null signal will travel in -90° and 90° directions. Thus, certain directions are disadvantaged relative to other directions on a single input receiver of a legacy wireless local area network device.

According to the invention, a different composite weighting is applied to each subcarrier on the M-1 transmit antennas. In this way, a different beam pattern is formed on each subcarrier, resulting in reduced power/energy loss in the worst direction. As shown in Figures 31 and 32.

Fig. 31 is a schematic diagram of the frame preamble formation method as shown in Fig. 7, which is suitable for popularized next-generation MIMO transmitters, especially for two-antenna next-generation MIMO transmitters. As shown, two preambles are generated: one for each active antenna. The first preamble 311 transmitted by the first antenna includes a double guard interval (GI2) 312, a first channel sense (CS 0,0) 315, a second channel sense (CS 0,1) 317, A guard interval (GI) 319 , a signal field (SIG) 321 , another guard interval (GI) 323 and a third channel sense (CS 0,2) 325 . The second preamble 327 transmitted by the second antenna includes a double guard interval (GI2) 329, a first channel sense (CS 1,0) 331, a second channel sense (CS 1,1) 333, A guard interval (GI) 335 , a signal field (SIG) 337 , another guard interval (GI) 339 and a third channel sense ( CS1 , 2 ) 341 .

In this embodiment, the following might be used for the various channel senses:

S ₀₁ =S ₀₀

${\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="10"\; label="s"\; filenames="A200510070136.000641.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}$

S ₁₁ =S ₁₀

S ₀₂ =S ₀₀

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="12"\; label="S"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}$

Listening from these channels, the weighting factors can be used as follows:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="10"\; label="s"\; filenames="A200510070136.000641.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="11"\; label="s"\; filenames="A200510070136.000951.png,A200510070136.000981.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="20"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 20</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 1</span>}& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ \mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]<span\; class="notranslate">\; \&Center\; Dot;</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& {\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}\end{array}\right]$

$<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}\\ {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}\end{array}\right]$

Wherein, the first number below the channel sense corresponds to the number of antennas, the second number corresponds to the number of characters, and k corresponds to the number of channel probes. For example, S _10,k corresponds to the first symbol transmitted on the first antenna sensed by the Kth channel.

In order to obtain a different beam direction characteristic for each subcarrier, the following formula is used:

${\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N\; subcarriers"\; filenames="A200510070136.000711.png,A200510070136.000841.png"\; state="\{\{state\}\}">N</figure-callout></span><figure-callout\; id="2"\; label="N\; subcarriers"\; filenames="A200510070136.000711.png,A200510070136.000841.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\frac{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N\; subcarriers"\; filenames="A200510070136.000711.png,A200510070136.000841.png"\; state="\{\{state\}\}">N</figure-callout></span><figure-callout\; id="2"\; label="N\; subcarriers"\; filenames="A200510070136.000711.png,A200510070136.000841.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

FIG. 32 is a schematic diagram of the manner in which a preamble of the frame format shown in FIG. 7 is formed for a next-generation three-antenna multiple-input multiple-output (MIMO) transmitter. As shown, three preambles are generated: one for each active antenna. The first preamble 351 transmitted by the first antenna includes a double guard interval (GI2) 353, a first channel sense (CS 0,0) 355, a second channel sense (CS 0,1) 357, a guard Interval (GI) 359, a signal field (SIG) 361, another guard interval (GI) 363, a third channel sense (CS 0, 2) 365, a third guard interval (GI) 367 and a fourth channel sense (CS 0,3)369. The second preamble 371 transmitted by the second antenna includes a double guard interval (GI2) 373, a first channel sense (CS 1,0) 375, a second channel sense (CS 1,1) 377, a guard interval (GI) 379, a signal field (SIG) 381, another guard interval (GI) 383, a third channel sense (CS1, 2) 385, a third guard interval (GI) 387 and a fourth channel sense ( CS 1,3) 389. The third preamble 391 transmitted by the third antenna includes a double guard interval (GI2) 393, a first channel sense (CS2, 0) 395, a second channel sense (CS 2, 1) 397, a guard interval (GI) 399, a signal field (SIG) 401, another guard interval (GI) 403, a third channel sense (CS 2, 2) 405, a third guard interval (GI) 407 and a fourth channel sense ( CS 2,3) 409.

For different channel sensing, the weighting factor matrix can be used as follows:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="10"\; label="s"\; filenames="A200510070136.000641.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="11"\; label="s"\; filenames="A200510070136.000951.png,A200510070136.000981.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="12"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="20"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 20</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}\\ {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="30"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 30</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="31"\; label="s"\; filenames="A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 31</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="32"\; label="s"\; filenames="A200510070136.000641.png,A200510070136.000951.png"\; state="\{\{state\}\}">s</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 32</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; k</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}\\ {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>}\\ {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}& {\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}\end{array}\right]$

In order to obtain a different beam direction characteristic for each subcarrier, the following formula is used:

_θk = π·k/6

φ _k = π·(k+4)/6

By adopting the method shown in Fig. 31 and Fig. 32, more signal energy can be transmitted, so that the channel estimation performed by the receiver is better. This enables zero-forcing (ZF) or least-square-error channel estimation (mostly adds/shifts) at the receiver to be simplified as follows:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ <span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}& <span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]<span\; class="notranslate">\; \&DoubleRightArrow;</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\left[\begin{array}{cc}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}& <span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}& <span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]$

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\left(\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\\ \mathrm{<span\; class="notranslate">\; 1</span>}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right)<span\; class="notranslate">\; \&DoubleRightArrow;</span>\underset{\mathrm{<span\; class="notranslate">\; 51</span>}}{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\left(\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\\ \mathrm{<span\; class="notranslate">\; 1</span>}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& \frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right)$

The channel can be estimated using previous information on the antenna beamforming coefficients for each subcarrier, after which these coefficients do not have to be applied to the remaining transmitted symbols. The advantage of this is that no additional multiplication operation is required at the transmitter, since the LTRN sequence can simply be looked up in the table.

The channel may be estimated without prior information on the antenna beamforming coefficients for each subcarrier, after which these coefficients are applied to the remaining transmit symbols. The benefit of this is that the channel estimation at the receiver is simplified (fewer multiplications), but the transmitter performs additional multiplications.

In the first case, the previous notation is used, and L=M:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}$

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; diag</span>}<span\; class="notranslate">\; (</span>\left[\begin{array}{cccc}\mathrm{<span\; class="notranslate">\; 1</span>}& {\mathrm{<span\; class="notranslate">\; e</span>}}^{\frac{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}{<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="l"\; filenames="A200510070136.000641.png,A200510070136.000711.png"\; state="\{\{state\}\}">l</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 6</span>}}}& <span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>& {\mathrm{<span\; class="notranslate">\; e</span>}}^{\frac{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 6</span>}}}\end{array}\right]<span\; class="notranslate">\; )</span>$

In the second case, the previous notation is used, and L=M:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 00</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}$

Note that it is possible to refine the channel estimation by doubling the entire M-long sequence p times. The fine estimate can be obtained by simple averaging. The overhead is the same as the single active emitter approach described on slide 10, but the performance far exceeds it.

For the backward compatible preamble example, where the number of long training characters is M+1, longer sequences will consist of P×M+1 long training characters. There are p identical blocks of M characters, and the first and second characters are the same on each antenna.

Figure 33 is a schematic diagram of a guard interval (GI2) 236 and two long training sequences 348, 350 (I ₀₀ and I ₀₁ ). In this example, GI2 236 (a double-length guard interval, or Orthogonal Frequency Division Multiplexing (OFDM) cyclic _{prefix) is equal to the last part of I 01 236-1} , which may be 3.2 μs long and corresponds to a long training sequence. A general guard interval (GI) is the last 800ns of a character (pre-planned for characters).

Fig. 34 is a schematic diagram of cyclic shift. In this example, the tones 421, 423, and 425 of the long training sequence 348-2 of the frame for the second transmit antenna are relative to the corresponding tones 421, 423, and 425 of the long training sequence 348-1 of the frame of the first transmit antenna. Rotate by x ns. The duration of the sequence length of the cyclically shifted tones may be y ns.

Figure 35 is a schematic diagram of preambles for two transmit antennas. In this example, S ₀ is the legacy 802.11a short training sequence 157 (10 characters of 800ns duration each). S ₁ 157 of frame 104-2 is a 400 ns cyclic shift of S ₀ 157 of frame 104-1. The long training sequences 348, 350 (I ₀₀ and I ₀₁ ) are two legacy 802.11a long training characters (3200ns each plus 1600ns pre-planned GI2), where I ₀₀ =I ₀₁ . Frame 104-2, I ₁₀ and I11 348, 350 of the second antenna is a 1600 ns cyclic shift of I ₀₀ and I ₀₁ 348, 350 of frame 104-1 of the first antenna. The remainder of each frame includes a double guard interval 236, single guard intervals 220, 226, signal field 224 and a first data field 228 of the plurality of data fields.

FIG. 36 is a schematic diagram of preambles for three transmit antennas. Each preamble of frames 104-1, 104-2, and 104-3 includes a short training sequence (S ₀ , S ₁ , S ₂ ) 157, a double guard interval 236, a first long training sequence (I ₀₀ , I ₁₀ and I ₂₀ ) 348, second long training sequence (I ₀₁ , I ₁₁ and I ₂₁ ) 350, single guard interval 220, signal field 224, second double guard interval 236, third long training sequence (I ₀₂ , I ₁₂ and I ₂₂ ) 348, another single guard interval 226 and a first data field 228 of the plurality of data fields.

As shown, S _{1 .} . . S ₂ is a k×200 ns cyclic shift of S ₀ , where K=I . . . 2. I ₀₀ and I ₀₁ are 802.11a long training characters. I ₁₀ and I ₁₁ are 1600ns cyclic shifted replicas of I ₀₀ and I ₀₁ . I ₂₀ and I ₂₁ are cyclically shifted replicas of Δ(delta)ns of I ₀₀ and I ₀₁ . I ₀₂ is the first 802.11a long training character with GI2. I ₁₂ is a 1600ns cyclic shifted copy of I ₀₂ . I ₂₂ is a replica of the first 802.11a long training character negated (ie -I ₂₀ ) and a cyclic shift of Δ(delta)ns of pre-planned GI2. The signal field is located between two sets of training characters. In one embodiment, the delta (delta) value is in the range -200 to 200 (ns).

FIG. 37 is another schematic diagram of preambles for three transmit antennas. Each preamble of frames 104-1, 104-2, and 104-3 includes a short training sequence (S ₀ , S ₁ , S ₂ ) 157, a double guard interval 236, a first long training sequence (I ₀₀ , I ₁₀ and I ₂₀ ) 348, second long training sequence (I ₀₁ , I ₁₁ and I ₂₁ ) 350, single guard interval 220, signal field 224, second double guard interval 236, third long training sequence (I ₀₂ , I ₁₂ and I ₂₂ ) 348 , a fourth long training sequence (I ₀₃ , I ₁₃ and I ₂₃ ) 350 , another single guard interval 226 and a first data field 228 of the plurality of data fields.

As shown, S _{1 .} . . S ₂ is a k×200 ns cyclic shift of S ₀ , where K=1 . . . 2. I ₀₀ and I ₀₁ are 802.11a long training characters. I ₁₀ and I ₁₁ are 1.6 μs cyclically shifted replicas of I ₀₀ and I ₀₁ . I ₂₀ and I ₂₁ are cyclically shifted replicas of Δ(delta)ns of I ₀₀ and I ₀₁ . I ₀₂ and I ₀₃ are 802.11a long training characters. I ₁₂ and I ₁₃ are 1.6 μs cyclically shifted replicas of I ₀₂ and I ₀₃ . I ₁₂ and I ₁₃ are cyclic shifted replications of Δ(delta)ns of I ₀₂ and I ₀₃ . I ₂₂ and I ₂₃ are 802.11a long training character negated (negated (-I ₂₀ ,-I ₂₁ ) cyclically shifted replicas of Δ(delta) ns. Signal field 224 is located between two sets of training characters. In a In an embodiment, the delta value is in the range -200 to 200 (ns).

Figure 38 is a schematic diagram of preambles for four transmit antennas. Each preamble of frames 104-1, 104-2, 104-3, and 104-4 includes a short training sequence (S ₀ , S ₁ , S ₂ , S ₃ ) 157, a double guard interval 236, a first long training sequence Sequence (I ₀₀ , I ₁₀ , I ₂₀ , I ₃₀ ) 348, second long training sequence (I ₀₁ , I ₁₁ , I ₂₁ , I ₃₁ ) 350, single guard interval 220, signal field 224, second double guard interval 236, the third long training sequence (I ₀₂ , I ₁₂ , I ₂₂ , I ₂₃ ) 348, the fourth long training sequence (I ₀₃ , I ₁₃ , I ₂₃ , I ₃₃ ) 350, another single guard interval 226 and multiple The first data field 228 of the data fields.

As shown in the figure, S ₁ ... S ₃ is a k×200 ns cyclic shift of S ₀ , where K=1 ... 3. I ₀₀ and I ₀₁ are 802.11a long training characters. I ₁₀ and I ₁₁ are 1600ns cyclic shifted replicas of I ₀₀ and I ₀₁ . I ₂₀ and I ₂₁ are cyclically shifted replicas of Δ(delta)ns of I ₀₀ and I ₀₁ . I ₃₀ and I ₃₁ are cyclically shifted replicas of (1600+Δ)ns of I ₀₀ and I ₀₁ . I ₀₂ and I ₀₃ are 802.11a long training characters. I ₁₂ and I ₁₃ are 1600ns cyclic shifted replicas of I ₀₂ and I ₀₃ . I ₁₂ and I ₁₃ are cyclic shifted replications of Δ(delta)ns of I ₀₂ and I ₀₃ . I ₂₂ and I ₂₃ are cyclic shifts of Δ(delta)ns of the 802.11a long training character negated (-I ₂₀ , -I ₂₁ ). I ₃₂ and I ₃₃ are (1600+Δ)ns cyclic shifts of the 802.11a long training character negated (-I ₃₀ , -I ₃₁ ). In one embodiment, the delta value is selected from the range -200 to 200 (ns).

Those of ordinary skill in the art will appreciate that the terms "substantially" or "approximately", as may be used herein, provide an industry-accepted tolerance for the corresponding term. Such industry-accepted tolerances range from less than 1% to 20% and correspond to, but are not limited to, component values, integrated circuit processing fluctuations, temperature fluctuations, rise and fall times, and/or thermal noise. Those of ordinary skill in the art will also appreciate that the term "operably coupled," as it may be used herein, includes both direct and indirect connections through another component, element, circuit, or module, where for an indirect connection, an intervening component , component, circuit or module does not change the information of the signal, but can adjust its current level, voltage level and/or power level. As those of ordinary skill in the art will appreciate, inferential coupling (ie, one element is inferentially coupled to another element) includes both direct and indirect connections between two elements by the same means as "operably coupled." As will also be appreciated by those of ordinary skill in the art, the term "compares favorably," as it may be used herein, means that a comparison between two or more elements, items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal 1 has a greater amplitude than signal 2, favorable comparison results can be obtained when signal 1 has a greater amplitude than signal 2 or when signal 2 has a smaller amplitude than signal 1.

Above, various embodiments of wireless communication in a wireless communication system including a plurality of wireless communication devices of different protocols have been discussed. As will be appreciated by those skilled in the art, other embodiments can be derived from the teachings of the present invention without departing from the scope of the claims of the present invention.

This application claims priority to the following U.S. patent applications:

1. Application number: 60/544,605, application date: February 13, 2004, invention name: Multi-protocol wireless communication in wireless local area network (Multiple Protocol Wireless Communications ina WLAN);

2. Application number: 60/545,854, application date: February 19, 2004, invention name: WLAN Transmitter Having High DataThroughput (WLAN Transmitter Having High DataThroughput);

3. Application number: 60/568,914, application date: May 7, 2004, invention name: MIMO Protocol for Wireless Communications;

4. Application number: undecided, application date: May 24, 2004, invention name: Preamble Formats for MIMO Wireless Communications (Preamble Formats for MIMO Wireless Communications);

5. Application number: 60/575,933, application date: June 1, 2004, invention title: the same as this application.

Mode selection table:

Table 1: 2.4GHz, 20/22MHz channel bandwidth, 54Mbps maximum bit rate rate modulation coding rate NBPSC NCBPS NDBPS EVM sensitivity ACR AACR 1 Barker BPSK 2 Barker QPSK 5.5 CCK 6 BPSK 0.5 1 48 twenty four -5 -82 16 32 9 BPSK 0.75 1 48 36 -8 -81 15 31 11 CCK 12 QPSK 0.5 2 96 48 -10 -79 13 29 18 QPSK 0.75 2 96 72 -13 -77 11 27 twenty four 16-QAM 0.5 4 192 96 -16 -74 8 twenty four 36 16-QAM 0.75 4 192 144 -19 -70 4 20 48 64-QAM 0.666 6 288 192 -twenty two -66 0 16 54 64-QAM 0.75 6 288 216 -25 -65 -1 15

Table 2: Channel Selection for Table 1 channel Frequency (MHz) 1 2412 2 2417 3 2422 4 2427 5 2432 6 2437 7 2442 8 2447 9 2452 10 2457 11 2462 12 2467

Table 3: Power Spectral Density (PSD) mask of Table 1 psd mask 1 frequency offset dBr -9MHz to 9MHz 0 +/-11MHz -20 +/-20MHz -28 +/-30MHz and greater -50

Table 4: 5GHz, 20MHz channel bandwidth, 54Mbps maximum bit rate rate modulation coding rate NBPSC NCBPS NDBPS EVM sensitivity ACR AACR 6 BPSK 0.5 1 48 twenty four -5 -82 16 32 9 BPSK 0.75 1 48 36 -8 -81 15 31 12 QPSK 0.5 2 96 48 -10 -79 13 29 18 QPSK 0.75 2 96 72 -13 -77 11 27 twenty four 16-QAM 0.5 4 192 96 -16 -74 8 twenty four 36 16-QAM 0.75 4 192 144 -19 -70 4 20 48 64-QAM 0.666 6 288 192 -twenty two -66 0 16 54 64-QAM 0.75 6 288 216 -25 -65 -1 15

Figure 5: Channel selection from Table 4 channel Frequency (MHz) nation channel Frequency (MHz) nation 240 4920 Japan 244 4940 Japan 248 4960 Japan 252 4980 Japan 8 5040 Japan 12 5060 Japan 16 5080 Japan 36 5180 America/Europe 34 5170 Japan 40 5200 America/Europe 38 5190 Japan 44 5220 America/Europe 42 5210 Japan 48 5240 America/Europe 46 5230 Japan 52 5260 America/Europe 56 5280 America/Europe 60 5300 America/Europe 64 5320 America/Europe 100 5500 America/Europe 104 5520 America/Europe 108 5540 America/Europe 112 5560 America/Europe 116 5580 America/Europe 120 5600 America/Europe 124 5620 America/Europe 128 5640 America/Europe 132 5660 America/Europe 136 5680 America/Europe 140 5700 America/Europe 149 5745 U.S. 153 5765 U.S. 157 5785 U.S. 161 5805 U.S. 165 5825 U.S.

Table 6: 2.4GHz, 20MHz channel bandwidth, 192Mbps maximum bit rate rate TX antenna ST coding rate modulation coding rate NBPSC NCBPS NDBPS 12 2 1 BPSK 0.5 1 48 twenty four twenty four 2 1 QPSK 0.5 2 96 48 48 2 1 16-QAM 0.5 4 192 96 96 2 1 64-QAM 0.666 6 288 192 108 2 1 64-QAM 0.75 6 288 216 18 3 1 BPSK 0.5 1 48 twenty four 36 3 1 QPSK 0.5 2 96 48 72 3 1 16-QAM 0.5 4 192 96 144 3 1 64-QAM 0.666 6 288 192 162 3 1 64-QAM 0.75 6 288 216 twenty four 4 1 BPSK 0.5 1 48 twenty four 48 4 1 QPSK 0.5 2 96 48 96 4 1 16-QAM 0.5 4 192 96 192 4 1 64-QAM 0.666 6 288 192 216 4 1 64-QAM 0.75 6 288 216

Figure 7: Channel selection from Table 6 channel Frequency (MHz) 1 2412 2 2417 3 2422 4 2427 5 2432 6 2437 7 2442 8 2447 9 2452 10 2457 11 2462 12 2467

Table 8: 5GHz, 20MHz channel bandwidth, 192Mbps maximum bit rate rate TX antenna ST coding rate modulation coding rate NBPSC NCBPS NDBPS 12 2 1 BPSK 0.5 1 48 twenty four twenty four 2 1 QPSK 0.5 2 96 48 48 2 1 16-QAM 0.5 4 192 96 96 2 1 64-QAM 0.666 6 288 192 108 2 1 64-QAM 0.75 6 288 216 18 3 1 BPSK 0.5 1 48 twenty four 36 3 1 QPSK 0.5 2 96 48 72 3 1 16-QAM 0.5 4 192 96 144 3 1 64-QAM 0.666 6 288 192 162 3 1 64-QAM 0.75 6 288 216 twenty four 4 1 BPSK 0.5 1 48 twenty four 48 4 1 QPSK 0.5 2 96 48 96 4 1 16-QAM 0.5 4 192 96 192 4 1 64-QAM 0.666 6 288 192 216 4 1 64-QAM 0.75 6 288 216

Figure 9: Channel selection from Table 8 channel Frequency (MHz) nation channel Frequency (MHz) nation 240 4920 Japan 244 4940 Japan 248 4960 Japan 252 4980 Japan 8 5040 Japan 12 5060 Japan 16 5080 Japan 36 5180 America/Europe 34 5170 Japan 40 5200 America/Europe 38 5190 Japan 44 5220 America/Europe 42 5210 Japan 48 5240 America/Europe 46 5230 Japan 52 5260 America/Europe 56 5280 America/Europe 60 5300 America/Europe 64 5320 America/Europe 100 5500 America/Europe 104 5520 America/Europe 108 5540 America/Europe 112 5560 America/Europe 116 5580 America/Europe 120 5600 America/Europe 124 5620 America/Europe 128 5640 America/Europe 132 5660 America/Europe 136 5680 America/Europe 140 5700 America/Europe 149 5745 U.S. 153 5765 U.S. 157 5785 U.S. 161 5805 U.S. 165 5825 U.S.

Table 10: 5GHz, 40MHz channel and maximum bit rate of 486Mbps rate TX antenna ST coding rate modulation coding rate NBPSC 13.5Mbps 1 1 BPSK 0.5 1 27Mbps 1 1 QPSK 0.5 2 54Mbps 1 1 16-QAM 0.5 4 108Mbps 1 1 64-QAM 0.666 6 121.5Mbps 1 1 64-QAM 0.75 6 27Mbps 2 1 BPSK 0.5 1 54Mbps 2 1 QPSK 0.5 2 108Mbps 2 1 16-QAM 0.5 4 216Mbps 2 1 64-QAM 0.666 6 243Mbps 2 1 64-QAM 0.75 6 40.5Mbps 3 1 BPSK 0.5 1 81Mbps 3 1 QPSK 0.5 2 162Mbps 3 1 16-QAM 0.5 4 324Mbps 3 1 64-QAM 0.666 6 365.5Mbps 3 1 64-QAM 0.75 6 54Mbps 4 1 BPSK 0.5 1 108Mbps 4 1 QPSK 0.5 2 216Mbps 4 1 16-QAM 0.5 4 432Mbps 4 1 64-QAM 0.666 6 486Mbps 4 1 64-QAM 0.75 6

Table 11: Power spectral density (PSD) mask for Table 10 psd mask 2 frequency offset dBr -19MHz to 19MHz 0 +/-21MHz -20 +/-30MHz -28 +/-40MHz and greater -50

Figure 12: Channel selection from Table 10 channel Frequency (MHz) nation channel Frequency (MHz) nation 242 4930 Japan 250 4970 Japan 12 5060 Japan 38 5190 America/Europe 36 5180 Japan 46 5230 America/Europe 44 5520 Japan 54 5270 America/Europe 62 5310 America/Europe 102 5510 America/Europe 110 5550 America/Europe 118 5590 America/Europe 126 5630 America/Europe 134 5670 America/Europe 151 5755 U.S. 159 5795 U.S.

Claims (10)

1. A method for multi-input multi-out wireless communication, comprising: Determine the protocol of wireless communication devices in the vicinity; determining whether the protocols of the wireless communication devices in the vicinity belong to the same protocol; Determine the number of transmit antennas; When the protocols of the wireless communication devices in the nearby area belong to the same protocol, according to the number of the transmitting antennas, using at least one of character cyclic shift, pitch cyclic shift, loose tone configuration and loose character configuration The preamble of the frame for wireless communication is formatted. 2. The method according to claim 1, comprising: when the protocols of the wireless communication devices in the nearby area belong to the same protocol, formatting the preamble of the frame of the wireless communication in the following format: using legacy format for the first part of the frame; using at least one of character cyclic shift, pitch cyclic shift, loose tone configuration, and loose character configuration for the remainder of the preamble of the frame, depending on the number of transmit antennas . 3. A method for generating a preamble of a frame for MIMO wireless communication, the method comprising, for each transmitting antenna of MIMO wireless communication: generating a carrier detect field, wherein the carrier detect field is cyclically shifted from transmit antenna to transmit antenna; generating a first channel sounding field, wherein the first channel sounding field is cyclically shifted from transmit antenna to transmit antenna; and Generate a signal field. 4. The method of claim 3, comprising generating a double guard interval between said carrier sounding field and said first channel sensing field. 5. The method of claim 3, comprising generating a single guard interval between said first channel-sensing field and said signal field. 6. The method of claim 3, further comprising: generating a short training sequence (STS) following a legacy (legacy) wireless communication protocol as the carrier sounding field; generating two long training sequences (LTS) following a legacy wireless communication protocol as the first channel sensing field, wherein the first long training sequence of the two long training sequences is cyclically shifted from transmit antenna to transmit antenna bits, the second long training sequence in the two long training sequences is cyclically shifted. 7. A radio frequency transmitter comprising: a baseband processing module operably coupled to convert outbound data into outbound character strings; a transmitter portion operatively coupled to convert said outbound character string into an outbound radio frequency signal, said baseband processing module further operatively coupled to: generating a carrier sounding field, wherein the carrier sounding field is cyclically shifted from transmit antenna to transmit antenna; generating a first channel sensing field, wherein the first channel sensing field is cyclically shifted from transmit antenna to transmit antenna; Generate a signal field. 8. The radio frequency transmitter of claim 7, wherein the baseband processing module is further operatively coupled to generate a double guard interval between the carrier sounding field and the first channel sensing field. 9. The radio frequency transmitter of claim 7, wherein the baseband processing module is further operatively coupled to generate a single guard interval between the first channel sense field and the signal field. 10. The radio frequency transmitter of claim 7, wherein the baseband processing module is further operatively coupled for: generating a short training sequence following a legacy (legacy) wireless communication protocol as the carrier sounding field; generating two long training sequences following a legacy wireless communication protocol as the first channel sensing field, wherein, from transmit antenna to transmit antenna, the first long training sequence of the two long training sequences is cyclically shifted, so The second long training sequence in the two long training sequences is cyclically shifted.

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