HK1191774A - Frame formatting for communications - Google Patents

Abstract

The present invention is directed to frame formatting for communications, specifically, frame formatting for communications within single user, multiple user, multiple access, and/or MIMO wireless communications. A signal is processed within a communication device using at least two respective downclocking ratios (e.g., a first downclocking ratio applied to a first portion of the signal such as a frame or packet extracted there from, a second downclocking ratio applied to a second portion of the signal). Alternatively, a signal is divided into more than two respective portions, and different respective downclocking ratios are applied to those different respective portions (e.g., a first downclocking ratio applied to a first portion of the signal, and so on up to an n-th downclocking ratio applied to an n-th portion of the signal). Some implementations apply a singular or common downclocking ratio to more than one portion of the signal (which may be contiguous/adjacent or non-contiguous/non-adjacent within the signal).

Description

Frame formatting for communications

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority from U.S. provisional patent application US61/639,050 filed on 26/4/2012, the U.S. provisional patent application US61/811,022 filed on 11/4/2013, and U.S. patent application US13/861,792 filed on 12/4/2013, which are incorporated herein by reference in their entirety.

Technical Field

The present invention generally relates to communications; and more particularly to frame formatting within single-user, multi-access, and/or MIMO wireless communications.

Background

The communication system supports wireless and wired communications between wireless and/or wired communication devices ranging from national and/or international cellular telephone systems to the internet to point-to-point home wireless networks and operating in accordance with more than one communication standard. For example, a wireless communication system may operate in accordance with one or more standards including, but not limited to, IEEE802.11x, Bluetooth, Advanced Mobile Phone System (AMPS), digital AMPS, Global System for Mobile communications (GSM), and the like, and/or variations thereof.

In some cases, the wireless communication between the Transmitter (TX) and the Receiver (RX) is a single-output single-input (SISO) communication. Other types of wireless communication include single-input multiple-output (SIMO) (e.g., a single TX processes data into RF signals for transmission to an RX that includes more than two antennas and more than two RX paths), multiple-input single-output (MISO) (e.g., a TX includes more than two transmission paths (e.g., digital-to-analog converters, filters, upconversion modules, and power amplifiers) that each convert a respective portion of a baseband signal to an RF signal for transmission to an RX via a respective antenna), and multiple-input multiple-output (MIMO) (e.g., a TX and an RX each include multiple paths such that the TX processes data in parallel using spatial and temporal coding functions to produce more than two data streams, and an RX receives multiple RF signals via multiple RX paths to reacquire the data streams using spatial and temporal decoding functions).

Disclosure of Invention

The present invention provides an apparatus comprising: at least one communication interface to receive signals from at least one other apparatus; and a processor for: processing the signal to extract packets or frames therefrom; and down-converting a first portion of the packet or frame having a first fast fourier transform structure and further comprising a signal field with a first down-ratio and down-converting a second portion of the packet or frame having a second fast fourier transform structure and further comprising at least one of a long training field and a data portion with a second down-ratio to generate a down-converted packet or down-converted frame.

Preferably, the second frequency reduction ratio is relatively higher or larger than the first frequency reduction ratio.

Preferably, the first portion of the packet or frame comprises a first signal field and the second portion of the packet or frame comprises at least one of a long training field, a second signal field, and a data portion.

Preferably, the first portion of the packet or frame has a 64-fast fourier transform structure; and the second portion of the packet or frame has a 128-fast fourier transform structure.

Preferably, the apparatus is a wireless station; and at least one other apparatus is an access point.

The present invention also provides an apparatus comprising: at least one communication interface to receive signals from at least one other apparatus; and a processor for: processing the signal to extract packets or frames therefrom; and down-packing a first portion of the packet or frame with a first down-conversion ratio and down-packing a second portion of the packet or frame with a second down-conversion ratio to generate a down-packed or down-frame.

Preferably, the first portion of the packet or frame comprises a signal field and the second portion of the packet or frame comprises at least one of a long training field and a data portion.

Preferably, the first portion of the packet or frame comprises a signal field and the second portion of the packet or frame comprises at least one of a long training field and a data portion; and the second downconversion ratio is relatively higher or greater than the first downconversion ratio.

Preferably, the first portion of the packet or frame comprises a first signal field and the second portion of the packet or frame comprises at least one of a long training field, a second signal field, and a data portion.

Preferably, the first portion of the packet or frame has a first fast fourier transform structure; and a second portion of the packet or frame has a second fast fourier transform structure.

Preferably, the first portion of the packet or frame has a 64-fast fourier transform structure; and the second portion of the packet or frame has a 128-fast fourier transform structure.

Preferably, the ratio of the first and second downconversion ratios is exponential to 2.

Preferably, the apparatus is a wireless station; and at least one other apparatus is an access point.

The invention also provides a method for operating a communication device, the method comprising: operating at least one communication interface of a communication device to receive signals from at least one other communication device; and processing the signal to extract packets or frames therefrom; and down-packing a first portion of the packet or frame with a first down-conversion ratio and down-packing a second portion of the packet or frame with a second down-conversion ratio to generate a down-packed or down-frame.

Preferably, the first portion of the packet or frame comprises a signal field and the second portion of the packet or frame comprises at least one of a long training field and a data portion.

Preferably, the first portion of the packet or frame comprises a signal field and the second portion of the packet or frame comprises at least one of a long training field and a data portion; and the second downconversion ratio is relatively higher or greater than the first downconversion ratio.

Preferably, the first portion of the packet or frame comprises a first signal field and the second portion of the packet or frame comprises at least one of a long training field, a second signal field, and a data portion.

Preferably, the first portion of the packet or frame has a first fast fourier transform structure; and a second portion of the packet or frame has a second fast fourier transform structure.

Preferably, the first portion of the packet or frame has a 64-fast fourier transform structure; and the second portion of the packet or frame has a 128-fast fourier transform structure.

Preferably, the communication device is a wireless station; and at least one other communication device is an access point.

Drawings

Fig. 1 is a diagram illustrating an embodiment of a wireless communication system.

Fig. 2 is a diagram illustrating an embodiment of a wireless communication device.

Fig. 3 is a diagram illustrating an embodiment of a wireless communication device and a cluster that may be employed to support communication with at least one other wireless communication device.

Fig. 4 shows an embodiment of OFDM (orthogonal frequency division multiplexing).

Fig. 5 illustrates an embodiment of a division of Television (TV) channels.

Fig. 6 illustrates an embodiment of an option for a shorter frame format (e.g., frame format-option a).

Fig. 7 shows an alternative embodiment of an option for a shorter frame format (e.g., frame format-option B).

Fig. 8 shows yet another alternative embodiment of an option for a shorter frame format (e.g., frame format-option C).

Fig. 9 illustrates an embodiment of different respective down-conversion ratios applied to different respective portions of a frame or packet.

Fig. 10 illustrates one embodiment of an embodiment that supports multiple contiguous channels (e.g., contiguous channel support-option a) (TVWS channelization with 5MHz in 6MHz channelization).

Fig. 11 shows an alternative embodiment of an embodiment that supports multiple contiguous channels (e.g., contiguous channel support-option B (1)).

Fig. 12 shows yet another alternative embodiment of an embodiment that supports multiple contiguous channels (e.g., contiguous channel support-option B (2)).

Fig. 13 shows another alternative implementation of an implementation that supports multiple contiguous channels (e.g., contiguous channel support-option C) (TVWS design of 4 contiguous channels).

Fig. 14 shows an embodiment of packet generation suitable for multiple channels.

Fig. 15 and 16 are diagrams illustrating embodiments of methods for operating more than one wireless communication device.

Detailed Description

Fig. 1 is a diagram illustrating an embodiment of a wireless communication system 10 including base stations and/or access points 12-16, wireless communication devices 18-32, and a network hardware component 34. The wireless communication devices 18 through 32 may be notebook hosts 18 and 26, personal digital assistant hosts 20 and 30, personal computer hosts 24 and 32, and/or cellular telephone hosts 22 and 28. Details of an embodiment of the wireless communication device are described in more detail with reference to fig. 2.

Base Stations (BSs) or Access Points (APs) 12 to 16 are operable to couple to the network hardware 34 via local area network connections 36, 38 and 40. Network hardware 34, which may be a router, gateway, bridge, modem, system controller, etc., provides a wide area network connection 42 for communication system 10. Each base station or access point 12 to 16 has an associated antenna or antenna array to communicate with wireless communication devices within its range. Typically, wireless communication devices register with base stations or access points 12 to 14 to receive service from the communication system 10. For direct connection (i.e., point-to-point communication), wireless communication devices communicate directly via an assigned channel.

Fig. 2 is a diagram illustrating an embodiment of a wireless communication device including host apparatuses 18 to 32 and an associated radio 60. For a cellular telephone host, the radio 60 is a built-in component. For a personal digital assistant host, a notebook computer host, and/or a personal computer host, the radio 60 may be a built-in or external component. For an access point or base station, the components are typically housed in a single structure. The host devices 18-32 include a processing module 50, a memory 52, a radio interface 54, an input interface 58, and an output interface 56. The processing module 50 and memory 52 execute corresponding instructions typically performed by a host device. For example, for a cellular telephone host device, the processing module 50 performs the corresponding communication functions according to a particular cellular telephone standard.

Radio interface 54 allows for the reception of data from radio 60 and the transmission of data to radio 60. For data received from radio 60 (e.g., inbound data), radio interface 54 provides data to processing module 50 for further processing and/or routing to output interface 56. Output interface 56 provides a connection to an output display device such as a display, monitor, speaker, etc. so that the received data can be displayed. The radio interface 54 also provides data from the processing module 50 to the radio 60. The processing module 50 may receive outbound data or generate data itself from input devices such as a keyboard, keypad, microphone, etc. via the input interface 58.

Radio 60 includes a host interface 62, a baseband processing module 64, a memory 66, Radio Frequency (RF) transmitters 68 through 72, a transmit/receive (T/R) module 74, antennas 82 through 86, RF receivers 76 through 80, and a local oscillation module 100. The baseband processing module 64 cooperates with operational instructions stored in the memory 66 to perform digital receiver functions and digital transmitter functions, respectively. Digital receiver functions include, but are not limited to, digital intermediate frequency to baseband conversion, demodulation, constellation mapping, decoding, sorting, fast fourier transformation, cyclic prefix removal, spatial and temporal decoding, and/or descrambling. As will be described in more detail with reference to later figures, the digital transmitter functions include, but are not limited to, scrambling, encoding, interleaving, constellation mapping, modulation, inverse fourier transform, cyclic prefix addition, spatial and temporal coding, and/or digital baseband to IF conversion.

In operation, the radio 60 receives outbound data 88 from a host device via the host interface 62. The baseband processing module 64 receives the outbound data 88 and generates one or more outbound symbol streams 90 based on the mode select signal 102. As the reader will appreciate, the mode select signal 102 will indicate the particular mode shown in the mode selection table. For example, mode select signal 102 may represent a frequency band of 2.4GHz or 5GHz, a channel bandwidth of 20MHz or 22MHz (e.g., a channel of 20MHz or 22MHz width), and a maximum bit rate of 54 megabits per second. In other embodiments, the channel bandwidth may be extended to 1.28GHz or more, while the maximum bit rate supported is extended to 1 gigabit per second or more. In this general category, the mode select signal will further represent a specific rate in the range from 1 megabit per second to 54 megabits per second. Further, the mode select signal will indicate a particular type of modulation including, but not limited to, barker code modulation, BPSK, QPSK, CCK, 16QAM, and/or 64 QAM. Also, in the mode selection table, a coding rate and the number of coding bits per subcarrier, the number of coding bits per OFDM symbol (NCBPS), and the data bits per OFDM symbol (NDBPS) are provided. The mode selection signal may also indicate a particular channelization of the corresponding mode for information in one of the mode selection tables (with respect to the other of the mode selection tables). It should be clearly noted that other types of channels having different bandwidths may be employed in other embodiments without departing from the scope and spirit of the present invention.

The baseband processing module 64 generates one or more outbound symbol streams 90 from the output data 88 based on the mode select signal 102. For example, if the mode selection signal 102 indicates that a single transmit antenna is utilized for the particular mode selected, the baseband processing module 64 will produce a single outbound symbol stream 90. Alternatively, if the mode select signal indicates 2, 3, or 4 antennas, the baseband processing module 64 will produce 2, 3, or 4 outbound symbol streams 90 corresponding to the number of antennas from the output data 88.

Depending on the number of outbound streams 90 generated by the baseband module 64, a corresponding number of RF transmitters 68 through 72 will be enabled to convert the outbound symbol streams 90 into outbound RF signals 92. The transmit/receive module 74 receives the outbound RF signals 92 and provides each outbound RF signal to a respective antenna 82-86.

When the radio 60 is in the receive mode, the transmit/receive module 74 receives more than one inbound RF signal via the antennas 82-86. The T/R module 74 provides the inbound RF signals 94 to more than one RF receiver 76-80. The RF receivers 76-80 convert the inbound RF signals 94 into a corresponding number of inbound symbol streams 96. The number of inbound symbol streams 96 will correspond to the particular mode of receiving data. The baseband processing module 64 receives the inbound symbol streams 96 and converts them to inbound data 98, which inbound data 98 is provided to the host devices 18-32 via the host interface 62.

In one embodiment of the radio 60, the radio 60 includes a transmitter and a receiver. The transmitter may include a MAC module, a PLCP module, and a PMD module. A Media Access Control (MAC) module, which may be implemented by the processing module 64, is operatively coupled to convert MAC Service Data Units (MSDUs) into MAC Protocol Data Units (MPDUs) according to the WLAN protocol. A Physical Layer Convergence Procedure (PLCP) module, which may be implemented in the processing module 64, is operatively coupled to convert MPDUs into PLCP Protocol Data Units (PPDUs) according to the WLAN protocol. A Physical Medium Dependent (PMD) module is operably coupled to convert the PPDU to a Radio Frequency (RF) signal according to one of the operating modes of the WLAN protocol, wherein the operating mode includes a plurality of inputs and a plurality of output combinations.

One embodiment of a Physical Medium Dependent (PMD) module includes an error protection module, a demultiplexing module, and a direction conversion module. An error protection module, which may be implemented in the processing module 64, is operatively coupled to reconstruct a PPDU (PCLP (physical layer convergence procedure) protocol data unit) to reduce transmission errors that generate error protection data. A demultiplexing module is operatively coupled to divide the error protection data into error protection data streams. The direct conversion module is operably coupled to convert the error protection data stream to a Radio Frequency (RF) signal.

Those of ordinary skill in the art will appreciate that the wireless communication device of fig. 2 may be implemented using more than one integrated circuit, according to any desired configuration or combination within more than one integrated circuit or components, modules, etc.

Fig. 3 is a diagram illustrating an embodiment of a wireless communication device and a cluster that may be employed to support communication with at least one other wireless communication device. In general, clustering can be viewed as a description of tone (tone) mapping, such as for OFDM symbols within or between more than one channel (e.g., a sub-divided portion of a spectrum), which can be located in more than one frequency band (e.g., a portion of the spectrum separated by a relatively larger amount). For example, various 20MHz channels may be located within or centered around the 5GHz band. The channels within any of these frequency bands may be continuous (e.g., adjacent to each other) or discontinuous (e.g., separated by some guard interval or band gap). In general, more than one channel may be located within a given frequency band, and different frequency bands do not necessarily have the same number of channels therein. Again, clustering may be generally understood as the combination of more than one channel within more than one frequency band.

The wireless communication device of this illustration may be any of the various types and/or equivalents described herein (e.g., an AP, a WLAN apparatus, or other wireless communication device including, but not limited to, any of the apparatuses shown in fig. 1, etc.). A wireless communication device includes multiple antennas through which more than one signal may be transmitted to more than one receiving wireless communication device and/or received from more than one other wireless communication device. The cluster may be used to transmit signals via various ones or more selected antennas. For example, different clusters are shown for transmitting signals using respectively different ones of the antennas.

Furthermore, it should be noted that all of these wireless communication devices within the communication system may obviously support two-way communication to and from other wireless communication devices within the communication system. In other words, various types of transmitting wireless communication devices and receiving wireless communication devices may also support two-way communication to and from other wireless communication devices within the communication system. In general, these capabilities, functions, operations, etc. described herein may apply to any wireless communication device.

As set forth herein, the various aspects and principles of the invention and their equivalents may be applicable to various standards, protocols, and/or recommended practices (including those currently being developed), such as those in accordance with ieee802.11x (e.g., where x is a, b, g, n, ac, ad, ae, af, ah, etc.).

Fig. 4 shows an embodiment 400 of OFDM (orthogonal frequency division multiplexing). OFDM modulation may be viewed as the division of the available spectrum into narrowband subcarriers (e.g., lower data rate carriers). Typically, the frequency responses of these subcarriers overlap and are orthogonal. Each subcarrier may be modulated using any of a variety of modulation coding techniques. A given frame or packet may be allocated across more than one OFDM symbol and different respective down-conversion ratios may be applied to different respective portions of the frame or packet.

Fig. 5 shows an embodiment 500 of dividing Television (TV) channels. Some wireless communication devices may be implemented to operate within a spectrum that is typically used exclusively by television channels. For example, television channels operating according to broadcast television may operate using specific portions of the electromagnetic spectrum. Generally, frequencies associated with UHF and VHF may be employed for broadcast television. However, some wireless communication devices have the ability to operate using some or all of those portions of the spectrum when they are not used for television. For example, selective operation of a wireless communication device may be based on whether some or all of the portion of the spectrum typically used for broadcast television is in use. Generally, the portion of the spectrum that is typically dedicated to this use (e.g., broadcast television) may instead be used to operate the wireless communication device, such as in accordance with those operations within a wireless local area network (WLAN/WiFi) or other wireless communication system, network, or the like.

In light of the operational provisioning of the wireless communication device using the spectrum typically associated with television channels, care must be taken to ensure that the operation of the wireless communication device is based on not interfering with any broadcast television. For example, while the portion of any existing broadcast television and spectrum is given a primary or first priority, a secondary or second priority may be given for using the wireless communication device, the second priority being provided such that the wireless communication device may operate based on non-interference with broadcast television.

According to current rules and guidelines, including those provided by the Federal Communications Commission (FCC) in the united states, there are very strict guidelines under which the wireless communication device can operate using those portions of the spectrum typically associated with television channels. For example, very low spectral mask requirements (e.g., -55dB attenuation) are required at the respective edges of a 6MHz channel (e.g., according to a television channel [ at least in the united states ], the respective lower and upper band boundaries are typically separated by about 6MHz, such as according to VHF low band (band I), air broadcast channel 2 has a lower edge of 54MHz and a higher edge of 60MHz, air broadcast channel 3 has a lower edge of 60MHz and a higher edge of 66MHz, etc.) based on operation according to more than one broadcast television channel.

Generally, operating a channel in accordance with IEEE802.11x (e.g., where x is a, b, g, n, ac, ad, ae, af, ah, etc.) requires the wireless communication device to provide less attenuation than operating the spectrum normally associated with a TV channel. Ieee802.11af is one of the standards, protocols and/or proposed implementations under development that operate on a secondary, non-interfering basis for broadcast television channels for one or more wireless local area networks (WLAN/WiFi). Generally, global broadcast television channels use a particular width of the corresponding channel bandwidth. For the united states and other countries, a corresponding channel bandwidth of 6MHz is employed. For australia and other countries a corresponding channel bandwidth of 7MHz is employed. Wherein for european countries a corresponding channel bandwidth of 8MHz is used. Regardless of the specific channel bandwidth employed in a given application, one or more wireless local area networks (WLAN/WiFi) are supported for secondary, interference-free operation. It should also be noted that although some of the various embodiments and/or figures illustrated herein are directed to a particular 6MHz channel bandwidth, it should be noted that substantially any one or more of the respective aspects, embodiments and/or equivalents thereof of the present invention may be employed and applied to a respective different value of channel bandwidth (e.g., 7MHz, 8MHz and/or any other particular channel bandwidth). That is, although certain of the respective embodiments and/or figures herein are directed to an example implementation of a preferred 6MHz channel, any such aspect, embodiment, and/or equivalent thereof of the present invention may be applied to any other desired channel bandwidth without departing from the scope and spirit of the present invention.

For example, although there is an attenuation of about-10 dB at the edge of the ieee802.11x channel, the operation of a wireless communication device according to the ieee802.11x channel is acceptable. It will be appreciated that there is a very high spectral shadowing requirement (e.g., -55dB attenuation) for operation using the spectrum normally associated with TV channels compared to the requirement for normal operation in accordance with ieee802.11x channels (e.g., -10dB attenuation). Also, for operation using the spectrum typically associated with TV channels, there is a Power Spectral Density (PSD) limit on the amount of transmit power that can be used for any given portion of the bandwidth (e.g., a PSD limit in a given 100MHz bandwidth).

In one possible implementation, a clock ratio having a desired ratio (e.g., typically N) may be used to generate any one of a plurality of different respective channels. For example, for a 20MHz channel, the down 4 value would provide a 5MHz channel that would fit into the prescribed 6MHz bandwidth channel of the spectrum typically associated with a TV channel. Alternatively, considering a 20MHz channel, the value of down-conversion 5 would provide a 4MHz channel that would fit into the prescribed 6MHz bandwidth channel of the spectrum normally associated with a TV channel. It will be appreciated that different respective ratios of downconversion may be employed to provide four different respective bandwidth channels which may be specifically designed to fit within the prescribed 6MHz bandwidth channels appropriate for the spectrum typically associated with TV channels. In some implementations, it may be desirable to have relatively narrow channels (e.g., 4MHz channels as compared to 5MHz channels) in order to provide very low spectral shadowing requirements at the respective edges of a given 6MHz channel that are typically present in the spectrum associated with TV channels. Generally speaking, frequency division by N processing circuits, modules, functional blocks, etc. may be performed to perform such downconversion for a given signal (e.g., such as a signal having a frequency of 20MHz or other frequency) to generate at least one downconverted signal having a frequency of typically 20/NMHz (e.g., or generally in accordance with downconversion of a signal having a frequency of M MHz by a value of N, such as a frequency of M/N MHz). Such a down-conversion value is programmable and/or selectable as desired in different respective embodiments. For example, in some cases, a wireless communication device may be adaptive to select any of a plurality of different respective bandwidth channels based on any of a plurality of considerations. For example, in one case, a 2MHz bandwidth channel is preferred; in another case, a 3MHz bandwidth channel is optimal; and in yet another case, a 5MHz channel is acceptable. In general, appropriate signal downconversion can provide a signal having properties acceptable for use within a channel of the 6MHz bandwidth of the spectrum typically associated with a TV channel.

Further, note that adaptation may be made with respect to the amount of bandwidth within a given channel. For example, for a channel bandwidth of a particular width (e.g., 6 MHz), certain embodiments may operate by employing a bandwidth of a particular amount of bandwidth (e.g., 4MHz, 5MHz, etc.) within the given available channel bandwidth (e.g., 6 MHz). The particular amount of bandwidth employed within the available channel bandwidth may be modified and/or matched in time based on any of a number of considerations (e.g., spectral masking requirements, attenuation and/or filtering capabilities, operating conditions, changes in operating conditions, environmental considerations, etc.). For example, a first amount of bandwidth within the available channels may be employed at or during a first time, a second amount of bandwidth within the available channels may be employed at a second time of sequencing (ordering), and so on.

In some embodiments, appropriate frequency division of the signal into respective channels of a specified size may provide for specified upscaling (fast fourier transform (FFT) of size 64/128/256/512) of the ieee802.11ac physical layer. For example, as can be seen in the figure, a first clock (e.g., CLK 1) having a first frequency may be divided by a factor of N to generate a second clock (e.g., CLK 1/N) having a second frequency. In general, a first clock signal having a first frequency (or a set of clock signals each having a respective different first frequency) may be divided by a factor of N to produce a second clock signal having a second frequency (or a set of clock signals each having a respective different second frequency).

For example, in one particular embodiment, the first clock has a frequency of 20MHz and may be divided by a factor of N (where N may be programmable and/or some implementation may be selectable) to produce the second clock signal having a divided frequency of 20/N MHz. Different respective first and second clocks may be implemented and used for use of one or more first and second transceiver modules/circuits within the wireless communication device. For example, one or more first transceiver modules/circuits within the wireless communication device may employ a first clock having a frequency of 20MHz, and one or more second transceiver modules/circuits within the wireless communication device may employ a second clock having a frequency of 20/N MHz.

Each of the respective clocks within the plurality of groups may be selectively provided to different portions of one or more first/second transceiver modules/circuits. That is, within the first/second clocks, different ones of which may be provided to different respective portions (e.g., 20MHz to first portion, 20/N MHz to second portion, etc.) of one or more first/second transceiver modules/circuits. It should be noted that such respective transceiver modules/circuits may be implemented with different respective transmitter and receiver components, respectively. In some embodiments, a given communication device may include a single set of transceiver modules/circuits and, depending on the frequency of the clock signal provided thereto, will generate signaling in accordance with any of a number of corresponding communication protocols, standards, and/or recommended practices. That is, when the first clock frequency is employed, signaling may be generated in accordance with the first communication protocol, standard, and/or recommended practice. Thereafter, if a second clock frequency (e.g., such as a down-converted version of the first clock frequency) is employed, signaling may be generated in accordance with a second communication protocol, standard, and/or recommended practice.

A channel of a particular frequency may be desired at one or more other frequencies based on any one or more of a number of considerations (e.g., current operating conditions, current presence of broadcast TV within one or more TV channels, interference, noise, environmental conditions, etc.). Moreover, selection of a particular frequency may be guided by any one or more of such considerations, including those described above, as well as by very stringent spectral mask requirements when operating with portions of the spectrum typically associated with TV channels, rather than other frequencies. For example, in some cases, a 4MHz channel may be suitable and acceptable for achieving very stringent required spectral masking (e.g., being able to achieve-55 dB attenuation using a 4MHz channel at the 6MHz band edge) at the corresponding band edge (bands) of a 6MHz channel within the spectrum typically associated with a TV channel. In another case, a 5MHz channel may be suitable and acceptable for achieving very stringent requirements of spectral masking (e.g., being able to achieve-55 dB attenuation using a 4MHz channel at the 6MHz band edge) at the corresponding band edge of the 6MHz channel within the spectrum typically associated with TV channels. However, it may be that in some cases, the design and/or implementation of a given wireless communication device, or current operating conditions, will require the adoption of a relatively narrower channel. For example, in some cases, a narrower channel such as 2MHz may be the widest channel used while providing suitable and acceptable operation including adherence to very demanding spectral masks at the respective band edges in the 6MHz channel within the spectrum typically associated with TV channels (e.g., enabling-55 dB attenuation using the 4MHz channel at the 6MHz band edge).

It will be appreciated that certain modes of operation may provide different respective numbers of tones and/or subcarriers for use when employing different respective widths when using respective different channels, particularly when using operation according to OFDM. For example, if the portion of the frequency spectrum employed according to an OFDM symbol changes, the possible and/or available number of tones and/or subcarriers will also change, such as with reference to fig. 4.

In one embodiment, to implement a relatively larger percentage of cases where 6MHz TV channels may be used (e.g., as compared to an implementation where 5MHz channels are used with respect to 4MHz channels), other data subcarriers may be employed within the selectable operating modes.

It should be understood that with respect to operation on available TV channels, for a given bandwidth [ e.g., such as at 6MHz or 8MHz TVWS (television (TV) white space) channels ], more than one possible downconversion ratio may be employed to achieve a desired signal bandwidth. For example, for a down-converted IEEE802.11ac waveform, one or more corresponding down-conversion ratios may be employed to achieve one or more desired signal bandwidths. For example, for an available TV channel of 5MHz bandwidth (e.g., 5MHz of the available 6MHz in one example), a 20MHz IEEE802.11ac waveform may be used for downconversion at a 4 downconversion ratio. Similarly, when an 80MHz IEEE802.11ac waveform is used, a down-conversion ratio of 16 may be employed.

Generally, downconversion can be performed to assist in generating a signal waveform (e.g., a physical layer (PHY) waveform) to fit within a viable spectrum of available (e.g., a viable subset of bandwidth within a channel such as 6MHz or 8 MHz). More than one respective downconversion ratio may be employed (e.g., such as using 4 and 8 downconversion ratios), but in general any desired number of downconversion ratios having particular desired values may be employed.

The symbol period extended by the downconversion by a factor of N is longer than the Guard Interval (GI) by the same factor of N, the larger N, the longer the delay spread immunity will be accordingly. In certain preferred embodiments, a suitable TVWS design will enable support for delay spreads of up to several microseconds. For example, for N =4, the maximum supportable delay spread is 3.2 μ s, and for N =8, the maximum supportable delay spread is 6.4 μ s. In a desired embodiment, it may be preferable that N = 8. In some embodiments, a higher N than this is unnecessary, as the associated gains may be relatively less than the increase in complexity of an over-designed system.

It should be noted, however, that because the length of the preamble increases (e.g., in absolute microseconds), and MAC parameters such as short interframe space (SIFS) and SLOT increase accordingly, the Medium Access Control (MAC) throughput of the communication system generally decreases as the value of N increases. Here, various enhancements are employed to improve the efficiency of the overall system with a certain size of Fast Fourier Transform (FFT) waveform (e.g., 128FFT waveform and other examples) for a desired downconversion ratio (e.g., N = 8).

Fig. 6 illustrates an embodiment 600 of an option for a shorter frame format (e.g., frame format-option a). From some perspectives, a frame format corresponding to ieee802.11 ac-like may be considered a baseline frame format for generating a frame format corresponding to ieee802.11af under development after undergoing a modification in a particular situation.

When a higher downconversion ratio is used, it should be noted that each OFDM symbol and thus each corresponding preamble field shown (e.g., L-STF, L-LTF, L-SIG, VHT-SIG a, etc.) will be lengthened accordingly. For example, when using a downconversion ratio of N =8 as compared to a downconversion ratio of N =4, each respective OFDM symbol and thus each respective preamble field will be doubled. It should be noted that some improvement over a given frame format (e.g., down-conversion of a 128FFT waveform by a factor of 8) may be made with a down-conversion ratio of N =8 to result in a signal corresponding to a 5MHz channel (e.g., which is located within an available TV channel).

For the L-STF field, a corresponding field within the preamble is used to obtain the packet and requires a specific length independent of the OFDM symbol length. That is, the specific field is typically timing acquisition, packet detection, and the like. In some embodiments, the length of the corresponding field may be reduced by half (e.g., halved) by replacing the usual number of repetitions (e.g., 10) with a smaller number (e.g., 5) of repetitions. The number of STF samples remains the same, i.e. 160, when compared to the corresponding down-conversion ratios of N =4 and N = 8. However, the number of repetitions for N =4 is 10 (multiplied by 16 samples) and the number of repetitions for N =8 is 5 (multiplied by 32 samples). Alternatively, a corresponding L-STF field structure with a down-conversion ratio N =4 may be used, since there is no degradation and no appearance of a longer delay spread as is the case with status characters.

For the L-SIG and SIG a fields, three corresponding OFDM symbols are typically used. However, according to the evolving ieee802.11af for the new spectrum, the contents of these respective symbols corresponding to these respective fields may be combined into a smaller number of symbols (e.g., two symbols). In addition, the design of the 128FFT SIG field uses a DUP (duplicate) structure of the 64FFT SIG field. However, since the fundamental channel element is a subset of the available 6MHz channels (e.g., 5 MHz), if a 128FFT is used to span that subset of bandwidth (e.g., its 5MHz portion), then no DUP structure is needed and the information can use the entire one and only one OFDM symbol (with the additional advantage of using all 54 information bits). That is, all such information may be included within a single OFDM symbol (e.g., a 5MHz portion thereof) spanning the subset of bandwidth.

As seen with respect to the specific figures, savings can be made for the STF field as well as for the SIG field.

Fig. 7 illustrates an alternative embodiment 700 of a shorter frame format option (e.g., frame format-option B). For this illustration, the entire respective preamble fields (e.g., L-STF, L-LTF, and L-SIG + VHT-SIG A) (and, at the same time, also combining two separate SIG fields into one field consisting of two symbols), the IEEE802.11ac related 64FFT structure may be down-scaled by a factor of 4. Since the spectrum associated with the developing ieee802.11af is new, the contents of the L-SIG and VHT-SIG a fields may be combined into two separate symbols (e.g., considering an implementation that does not include any legacy devices since the developing ieee802.11af is new).

From this illustration, generation of packets can be performed with a mix of different respective FFT structures down-converted with different respective clock ratios. That is, considering one possible implementation, the generation of a packet may be carried out with a mix of a factor 4 down-converted 64FFT followed by a factor 8 down-converted 128FFT for the first four fields. Furthermore, if desired, to provide better delay spread immunity to the SIG field, a double-sized Guard Interval (GI) may be employed instead of the usual and conventional GI.

Also, with respect to the previous diagram, since the developing IEEE802.11af is directed to a new portion of the spectrum, the contents of the respective symbol L-SIG and VHT-SIG A fields may be merged into two respective symbols because no such legacy devices are available according to the developing IEEE802.11 af.

Fig. 8 illustrates yet another alternative implementation 800 of a shorter frame format option (e.g., frame format-option C). For this illustration, two or more corresponding co-existing FFT structures down-converted at different respective clock ratios may be employed. In this way, the respective down-conversion ratio is programmable, adaptively determined, selectable, etc. to eliminate the need to select or implement only a single down-conversion ratio that is best suited for all possible implementations and schemes. For example, by having the fixed portion of the preamble (e.g., the pre-VHT modulated field) operate according to a first frequency-down ratio (e.g., N =4, selected for relatively higher efficiency), and by having other portions of the packet use one of a plurality of possible frequency-down ratios, the overall efficiency or delay spread immunity may be enhanced. In general, it should be noted that the FFT structure and associated clock ratios corresponding to respective different portions of the packet may be adaptive, selectable, programmable, etc. That is, respective different downconversion ratios may be applied to respective different portions of the packet. In some embodiments, a fixed or predetermined down-conversion ratio may be used for one portion of the packet, while an adaptively determined, selected, etc. down-conversion ratio may be used for another portion of the packet. Generally speaking, a plurality of different respective downconversion ratios may be selectively applied to different respective portions of the packet.

Also, it should be noted that some designs may be made to keep the ratio between the respective different supported downconversion ratios exponential by a factor of 2, to achieve less complexity in implementation. For example, depending on the operation of using respective different downconversion ratios for respective different portions of a packet, implementations may be made such that all possible communication devices will always be able to listen to, understand, process, etc., a particular portion of a packet, and based on the respective decoded content therein within the particular portion of the packet, one or more (or all) of the other portions of the packet may be decoded. For example, in one particular embodiment, the pre-VHT modulated fields may be appropriately processed such that all communication devices will always be able to listen to, understand, process, etc. those particular fields of the packet. Based on the decoded content therein, one or more devices in the respective communication device will be able to decode one or more (or all) of the other portions of the packet.

A specific efficiency comparison may be made for the preamble code lengths employed in relation to the different respective down-conversion ratios of N =4, 8 and 8 for option a and N =8 for option B. For example, certain assumptions may be made regarding the efficiency comparison. For example, it may be assumed that in any case, two respective fields L-SIG and VHT-SIG a are combined into one respective field, the field L-STF comprises two symbols, the field L-LTF comprises two symbols, the field VHT-STF comprises one symbol, the field VHT-LTF comprises one symbol (for one spatial stream), and the field VHT-SIG B comprises one symbol.

A short symbol with a corresponding preamble length of 2+2+2+1+1+2=9 with a down ratio of N = 4.

The corresponding preamble length with a down ratio of N =8 is twice the link provided above, or 18 short symbols.

The corresponding preamble length with a downconversion ratio of N =8 and option a is a long symbol of 1+2+1+1+ 1=7, or a short symbol equal to 14 (providing a 22% saving).

The corresponding preamble length with a down ratio of N =8 and option B is 2+2+2 shorter by 1+1+1 longer by =12 short symbols (providing a saving of 33%). As a reminder to the reader, option B corresponds to a mix of different respective down-conversion ratios applied to different respective portions of the packet.

In general, observations can yield the following results: by increasing the downconversion ratio, and thus the OFDM symbol time, SIFS and SLO times should also be increased accordingly (e.g., such as linearly according to the downconversion ratio). However, it is understood that since the target channel widths are the same (e.g., regardless of the frequency reduction ratio), these respective parameters regarding MAC throughput may also be selected to be the same.

For example, for SIFS, SIFS is currently 16 μ s within ieee802.11g/n/ac and is equivalent to the sum of the receive and transmit turnaround times, MAC processing delay, and total receive delay from the antenna. If the basic ieee802.11af channel bandwidth is considered to be a specific value X (e.g. 5 MHz), then the dominant SIFS should be 16/X × 20 (for 5MHz, =64 μ s) regardless of the down-conversion ratio, since the turnaround time and processing delay are functions of the device clock, which in turn is a function of the system bandwidth. In addition, running a receiver with a faster clock can be used to reduce the number to about 16/X × 10 (for 5MHz, =32 μ s).

The CCA time, which is a function of the time taken to detect a signal with 90% probability, is currently 4MHz within ieee802.11g/n/ac. As the bandwidth for the ieee802.11af channel bandwidth decreases to a particular value X (e.g., 5 MHz), the corresponding time is expected to increase to 4/X20 (or 16 mus for 5 MHz).

For SLOT, SLOT consists of CCA time, air propagation time (which can be increased from 1 μ s to 3 μ s to fit larger cells) and MAC processing delay that they can remain unchanged for ieee802.11ac.

Thus, in summary, the improved efficiency is such that the following number is used for a single user 2 ms packet providing an instance of the gain in data efficiency using the method previously using a frequency reduction ratio of N =8 compared to N = 4.

N =4-78% data efficiency (meaning that 78% of the time is used for data in the remaining 22% of overhead usage including preamble, SIFS, etc.)

2.N=8-63.3%

N =8-68%, implemented with shorter SLOT and SIFS times based on the assumptions provided above and previous embodiments

4.N =8-72%, when in the above number 3 and with option a

N =8-75%, when in the above number 3 and with option B

Fig. 9 illustrates one embodiment 900 of different respective down-conversion ratios applied to different respective portions of a frame or packet. It will be appreciated that for processing a given signal, different respective down-conversion ratios may be used for different respective portions thereof. For example, considering the top of the figure, a packet or frame may be split into two respective portions, and a first downconversion ratio may be applied to the first portion, and a second downconversion ratio may be applied to the second portion. Alternatively, considering the bottom of the graph, a packet or frame may generally be divided into n corresponding portions (e.g., where n is an integer). A first downconversion ratio may be applied to the first portion, a second downconversion ratio may be applied to the second portion, and so on, up to the nth downconversion ratio. Note also that a given or same downconversion ratio may be applied to more than one respective section in alternative embodiments (e.g., a first downconversion ratio may be applied to the first section and the third section).

Fig. 10 illustrates an embodiment of an embodiment 1000 that supports multiple contiguous channels (e.g., contiguous channel support-option a). It should be noted that the operation according to ieee802.11ac supports the operation of 10/40/80/160MHz channel. Performing a directional downconversion of an ieee802.11ac waveform to a evolving ieee802.11af channel, which may consist of 6/12/24MHz channels, may have certain co-existence issues if the downconversion ratio employed does not fit very well with the corresponding channel used within the evolving ieee802.11af channel. For example, depending on the relatively stringent spectral masking requirements encountered, there may be some coexistence issues if the down-conversion ratio employed is not suitable for the corresponding evolving ieee802.11af channel. For example, there may be partially overlapping channels. Considering one possibility, if one channel occupies 5MHz of the 6MHz available channel bandwidth, then accordingly, 2 respective channels will occupy 10MHz of the 12MHz available channel bandwidth (e.g., two adjacent 6MHz channels) and correspondingly, 4 respective channels will occupy 20MHz of the 24MHz available channel bandwidth (e.g., for adjacent 6MHz channels).

It will be appreciated that the following may be established: wherein different respective Basic Service Sets (BSSs) employing different respective bandwidths may partially overlap with respect to each other and wherein respective communication devices are unable to properly read SIG fields of the different respective BSSs. That is, referring to the figure, it can be seen that there is no possibility of perfect alignment given a slight offset from each channel given that they do not perfectly overlap with respect to each other. Accordingly, all respective communication devices are accordingly unable to listen to, process, etc. all respective communication devices because they are disposed on different respective bandwidths, which may have only partial overlap in some cases.

Thus, a pure receiver-based implementation may be implemented such that the receiver operates to scan all corresponding frequency offsets to find the offset SIG field. That is, all corresponding frequency offsets are scanned to find the correct SIG field in the correct position. For example, the SIG field may be found in a 6MHz channel, offset by ± 500kHz (e.g., for 10 MHz), offset by ± 1500kHz (e.g., for a 20MHz channel), and offset by ± 1000kHz (e.g., for a 10MHz channel in different locations) taking into account certain assumptions as described above (e.g., 5/10/20MHz channelization). If the signal bandwidth is different than 5MHz, the corresponding offset will be different, but there is no a priori value and the receiver can then calculate all possible offsets to correctly decode the SIG field.

Fig. 11 shows an alternative embodiment 1100 of an embodiment that supports multiple contiguous channels (e.g., contiguous channel support-option B (1)). Referring to the figure, the SIG field may change such that it occupies only half of the bandwidth. In other words, using a 128FFT with a down ratio of N =8, the SIG field structure may change from DUP mode to repeat only once in the center of the packet. That is, the DUP mode may not need to be performed, and the corresponding SIG field may be made narrower, but placed in the center of the available bandwidth. For example, if a 64FFT with a down ratio of N =4 is used (and thus the SIG field is not DUP), then the down ratio of N =8 may be used for the SIG field in the LDS symbol that previously had a down ratio of N = 8.

Furthermore, regardless of the bandwidth used, the modification of the SIG position can be made such that it is always located at the center of a given TV channel, or as close as possible to the center of a TV channel within given limits. This may be effective, for example, so that the constraint is to have it be on OFDM tones that may not coincide with the center of each respective channel.

As can be appreciated with reference to this figure, in the following figures, the SIG field may be modified to occupy a relatively narrower bandwidth, also such that it always falls in the center of the available channel bandwidth (or as close to the center of the channel bandwidth as possible). Thus, even if the data within a packet falls in one particular channel, the receiver device will always be able to decode the SIG field according to the arrangement of the SIG field in the center of the available bandwidth.

Fig. 12 shows another alternative embodiment 1200 of an embodiment that supports multiple contiguous channels (e.g., contiguous channel support-option B (2)). This figure shows an alternative embodiment comprising a plurality of respective SIG fields each having a narrower bandwidth than the previous figures.

In other words, a packet may be designed to start with a corresponding preamble field (e.g., STF/LTF/SIG) located at the center of the channel regardless of the corresponding packet bandwidth. That is, regardless of the bandwidth associated with a given packet (which may be any one of a number of possible packet bandwidths), the corresponding preamble field will be centered in the bandwidth associated with the given channel. The receiver may employ band pass filters implemented therein to tune the bandwidth of the different respective channel bandwidths and the available channel bandwidth to improve receiver sensitivity. Further, a given receiver will understand what the packet bandwidth of that particular packet is based on the SIG field (e.g., one channel, to channel, for channel, etc.), and their specific location relative to the SIG field location. That is, based on the location of the SIG field, the corresponding packet width may also be derived therefrom (implicitly, in some embodiments based on the location of the SIG field). For example, considering the implementation of four respective channels of the SIG field, the SIG field will convey information +1, +2, +3, or-1, +2 or-2, -1, +1, or-3, -2, -1 at a channel position relative to the channel that includes the SIG. In this example, the channel on which the corresponding channel was conveyed previously with respect to the SIG field (thus, implicitly indicating the packet bandwidth).

Fig. 13 shows another alternative embodiment 1300 of an embodiment that supports multiple contiguous channels (e.g., contiguous channel support-option C). Referring to the drawing, respective channels may be generated. For example, a unit of one channel may be used as a basis for transmitting two or more consecutive channels. Operation according to this value allows continuous operation (e.g., two or more respective TVWS channels that are not necessarily adjacent to each other, such that at least one other TVWS channel is interposed between the two). For example, there may be the following examples: where there is spectrum availability for fragmentation (e.g., in urban areas), and it makes sense to design two or more non-contiguous channels. Of course, it should be noted that continuous channel transmission may also be effective in other embodiments or in embodiments employing non-continuous channels.

In this embodiment, the individual channels (of N consecutive channels) may be separately filtered and then the frequency offset is positioned in the middle of the TVWS channel to avoid the offset problem described above with reference to option a and to avoid a different SIG field structure as option B.

Note also that different respective Modulation and Coding Sets (MCSs) may be used for different respective channels, respectively (e.g., such as where the respective channels are non-contiguous). That is, some channels may have relatively greater interference than other channels, some channels may have different propagation effects than other channels, etc., and MCS-based suitability between these respective channels may allow for at least one possible degraded service.

Fig. 14 shows an embodiment 1400 of generating packets suitable for multiple channels. There are several options for employing one channel as a building block to generate packets suitable for a particular number of channels.

Option 1: two or more independent channels (contiguous or non-contiguous) are defined that are not jointly encoded. They will then act as two independent channels with a common MAC, but more than two independent encoders each produce the required information bits to satisfy their own channel. However, in such embodiments, diversity may not be fully used.

Option 2: each channel coding is defined that allows for each channel MCS and also exploits channel diversity. A PPDU encoding process is performed on a per-channel basis, and all channel data are combined in a frequency mapped to a tone. The mapping to tones is done so that each encoder output enjoys diversity to all available channels. A simple mapping to tones uses a cyclic mapping such that each encoder output is mapped to tones in all channels (e.g., encoder 1 uses even tones on each channel and encoder 2 uses odd tones in each channel). The same cyclic mapping may be used for the 4 bonded channels so that each encoder splits the QAM symbols it outputs into each of the 4 channels.

Option 3: using the ieee802.11ac definition of a segment analyzer (a segment refers to an 80MHz channel), since each channel needs to be filtered separately, the segment inverse analyzer for the continuous 80+80 mode needs to be removed and the transmitter should follow the same structure as the non-continuous 80+ 80.

Option 4: instead of splitting the bits of the encoder output by using a segment analyzer, alternative embodiments may be used to optimize diversity by first mapping the bits to QAM symbols and then splitting the symbols in a cyclic manner between channels. Also, the same circular mapping may be used for any number of bonded channels (e.g., more than two clusters or channels such as combined in accordance with fig. 3).

However, the two previous options (options 3 and 4) may be viewed as slightly limited in that they inherently assume the same MCS on each channel. In the developing ieee802.11af (which may be referred to as TGaf), unlike ieee802.11as (which may be referred to as TGac), the channel may have a rather high SNR difference and the SINR difference due to TV channel interference-channels at VHF200MHz, UHF500MHz and 700MHz will have different propagation and interference, considerably larger than in the 5GHz band. As such, it may be preferable to use a different MCS for each channel (particularly for discontinuous operation), as also described above. As such, another option may be utilized.

Option 5: similar to option 1, except that the interleaved coded bits for more than two channels are mixed together first based on the ratio of Nbpsc (number of coded bits per subcarrier 1, 2, 4, 6, or 8) in each channel. For example, if one channel uses 16QAM (Nbpsc = 4) and one channel uses 64QAM (Nbpsc = 6), the new bit stream includes 4 bits from the encoder of channel 1 followed by 6 bits from the encoder of channel 2, and so on.

With regard to signaling that occupies bandwidth, unlike the ieee802.11ac standard, where channel locations are uniquely defined (e.g., a first 80MHZ channel occupies a first four 20MHZ channels, and a second 80MHZ channel occupies a second set of four 20MHZ channels, in other words, there is no overlap between 40, 80, or 160MHZ signals). TVWS channel availability varies between locations.

In this way, the signalling of which precise channels to use can be done when transmission on several consecutive channels occurs, since a device initially tuned to one channel cannot assume that it knows which channel to use. This is done by comparing the following information in the SIG field: bandwidth, one channel, two channels, four channels, etc.

The exact location is related to the location of the SIG field (e.g., in the case of four channels, the SIG field would convey information about the location of the channel relative to the channel that includes the SIG +1, +2, +3, or-1, +2, or-2, -1, +1, or-3, -2, -1). Note that if the 4 channels are bonded, the SIG field on each channel will not have exactly the same information because the position of each channel relative to the 4 bonded channels is different.

Fig. 15 and 16 are diagrams illustrating embodiments of methods for operating one or more wireless communication devices.

Referring to the method 1500 of fig. 15, within a communication device, the method 1500 begins with receiving a signal from at least one other communication device (e.g., via at least one communication interface of the communication device), as shown at block 1510. Method 1500 then proceeds by processing (e.g., via front-end processing, demodulation, pre-processing, etc.) the signal to extract packets or frames from the signal, as shown at block 1520.

The method 1500 proceeds by down-clocking a first portion of the packet or frame using a first down-clocking ratio and down-clocking a second portion of the packet or frame using a second down-clocking ratio to generate a down-clocked packet or frame, as shown at block 1530.

Referring to method 1600 of fig. 16, within a wireless device, method 1600 begins by receiving a signal from at least one other communication device (e.g., via at least one communication interface of the communication device), as shown at block 1610. However, method 1600 proceeds by processing (e.g., via front-end processing, demodulation, pre-processing, etc.) the signal to extract packets or frames from the signal, as shown at block 1620.

The method 1600 then proceeds by down-clocking a signal field (SIG) portion of the packet or frame using a first down-clocking ratio, as indicated by block 1630. The method 1600 continues by down-clocking the Long Training Field (LTF) portion and the data portion of the packet or frame using a second down-clocking ratio, as shown in block 1640. The method 1600 then proceeds by generating a down-converted packet or frame using the respective down-conversion portions (e.g., down-converted SIG and down-converted LTF and data portion), as shown in block 1650.

It is further noted that the respective operations and functions described herein with respect to the various methods may be performed in a wireless communication device, for example, using baseband processing modules and/or processing modules implemented in the wireless communication device (e.g., according to baseband processing module 64 and/or processing module 50 described with reference to fig. 2) and/or other components therein, including one or more baseband processing modules, one or more Medium Access Control (MAC) layers, one or more physical layers (PHYs) and/or other components, and/or the like. For example, such baseband processing modules may generate such signals and frames as described herein, and also perform various operations and analyses as described herein, or any other operations and functions described herein, or the like, or their equivalents.

In some embodiments, such baseband processing module and/or processing module (which may be implemented with the same device or separate devices) may perform such processing to generate signals for transmission to another wireless communication device (e.g., which may also include at least one of any number of radios and at least one of any number of antennas) using at least one of any number of radios and at least one of any data antennas, according to corresponding aspects of the present invention, and/or any other operations and functions, etc., described herein, or their respective equivalents. In some embodiments, such processing is performed cooperatively by a processing module in the first device and a baseband processing module in the second device. In other embodiments, such processing is performed entirely by the baseband processing module or processing module.

As used herein, data "base" and "approximately" provide an industry-acceptable tolerance of their respective terms and/or correlations between terms. Such industry-accepted tolerances range from one percent to fifty percent and correspond to, but are not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. This correlation between terms varies by a few percent to magnitude. As also used herein, the terms "operatively coupled to," "coupled to," and/or "coupled to" include direct couplings between items and/or indirect couplings between items via intermediate items (e.g., items that include, but are not limited to, components, elements, circuits, and/or modules), where for indirect couplings an intermediate item does not alter information of a signal but may adjust its current level, voltage level, and/or power level. As further used herein, "presumptive coupling" (i.e., coupling one element to another element by inference) includes indirect coupling between two items in the same manner as "coupling". As still further used herein, the term "operably" or "operably coupled to" means that an item includes one or more electrical connections, inputs, outputs, etc. to perform one or more of its respective functions when activated, and may further include a presumptive coupling to one or more other items. As still further used herein, the term "associated with" includes direct and/or indirect coupling of separate items and/or embedding of one item in another item. As used herein, the term "compares favorably", indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal 1 has a greater amplitude than signal 2, a favorable comparison may be made when the amplitude of signal 1 is greater than the amplitude of signal 2 or when the amplitude of signal 2 is less than the amplitude of signal 1.

Also as used herein, the terms "processing module," "processing circuit," and/or "processing unit" (e.g., including various modules and/or circuits, such as may be operable, implemented, and/or used for encoding, decoding, baseband processing, etc.) may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, microcontroller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any means for imparting hard coded and/or operational instructions to circuitry for processing signals (analog and/or digital). The processing module, processing circuit, and/or processing unit may have associated memory and/or integrated memory elements, which may be a single memory device, multiple memory devices, and/or embedded circuitry of the processing module, processing circuit, and/or processing unit. Such a memory device may be read-only memory (ROM), random-access memory (RAM), volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module, processing circuit, and/or processing unit includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributed located (e.g., through non-directly coupled cloud computing via a local area network and/or a wide area network). Further, it is noted that if the processing module, processing circuit, and/or processing unit implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or path circuitry, the memory and/or storage elements storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. It is further noted that the storage elements may store, and the processing modules, processing circuits, and/or processing units execute, hard-coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in one or more of the figures. Such memory devices or storage elements may be included in an article of manufacture.

The invention has been described above with the aid of method steps illustrating the performance of specific functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for the convenience of the description. Alternative boundaries and sequences may be defined so long as the specified functions and relationships are appropriately performed. Accordingly, any such alternative boundaries or sequences are within the scope and spirit of the claimed invention. Further, the boundaries of such functional building blocks may be arbitrarily defined for the convenience of the description. Optional boundaries may be defined whereby at least some important functions are appropriately performed. Similarly, flow diagram blocks may also be arbitrarily defined herein to illustrate some important functions. Flow diagram block boundaries and sequence may be otherwise limited to usage and still perform some important functions. Such alternative limitations of the functional building blocks and flow diagrams, and sequences thereof, are therefore within the spirit and scope of the claimed invention. It will also be appreciated by those of ordinary skill in the art that the functional building blocks and other illustrative blocks, modules, and components herein can be implemented in the manner shown or by discrete components, application specific integrated circuits, software adapted to perform the processing, and the like, or combinations thereof.

The present invention has also been described, at least in part, on the basis of one or more embodiments. Embodiments of the invention as used herein are intended to illustrate the invention, aspects thereof, features thereof, concepts thereof and/or examples thereof. Physical embodiments of devices, articles of manufacture, machines and/or processes for practicing the invention may include one or more of the aspects, features, concepts, examples, etc., described with reference to one or more embodiments discussed herein. Furthermore, from figure to figure, embodiments may incorporate the same or similarly named functions, steps, modules, etc. which may use the same or different reference numbers and, as such, may be the same or similar functions, steps, modules, etc. or different.

Unless specifically stated to the contrary, the elements, self-elements and/or signals between elements of any of the figures provided herein may be analog or digital, continuous-time or discrete-time, and single-ended or differential. This may also represent a differential signal path, for example, if the signal path is shown as a single ended path. Similarly, if the signal paths are shown as differential paths, they may also represent single-ended signal paths. Although one or more specific architectures are described herein, other architectures may be implemented which utilize one or more data buses which are not explicitly shown, direct connectivity between elements, and/or indirect coupling between other elements as would be appreciated by one of ordinary skill in the art.

The term "module" is used in describing the various embodiments of the present invention. A module includes a functional block that is implemented via hardware to perform one or more module functions, such as processing one or more input signals to produce one or more output signals. The hardware implementing the modules may itself operate in conjunction with software and/or firmware. As used herein, a module may include one or more sub-modules that are themselves modules.

Although specific combinations of features and functions are described herein, other combinations of features and functions are possible. The invention is not limited to the specific examples disclosed herein and obviously incorporates such other combinations.

Claims (10)

1. An apparatus, comprising:

at least one communication interface to receive signals from at least one other apparatus; and

a processor to:

processing the signal to extract packets or frames therefrom; and

the method further includes down-converting the packet or a first portion of the frame having a first fast fourier transform structure and further including a signal field with a first down-ratio and down-converting the packet or a second portion of the frame having a second fast fourier transform structure and further including at least one of a long training field and a data portion with a second down-ratio to generate a down-converted packet or a down-converted frame.

2. The apparatus of claim 1, wherein:

the second down-conversion ratio is relatively higher or larger than the first down-conversion ratio.

3. The apparatus of claim 1, wherein:

the first portion of the packet or the frame includes a first signal field and the second portion of the packet or the frame includes at least one of a long training field, a second signal field, and a data portion.

4. The apparatus of claim 1, wherein:

the first portion of the packet or the frame has a 64 fast fourier transform structure; and

the second portion of the packet or the frame has a 128-fast fourier transform structure.

5. The apparatus of claim 1, wherein:

the apparatus is a wireless station; and

the at least one other apparatus is an access point.

6. An apparatus, comprising:

at least one communication interface to receive signals from at least one other apparatus; and

a processor to:

processing the signal to extract packets or frames therefrom; and

down-converting a first portion of the packet or the frame with a first down-conversion ratio and down-converting a second portion of the packet or the frame with a second down-conversion ratio to generate a down-converted packet or a down-converted frame.

7. The apparatus of claim 6, wherein:

the first portion of the packet or the frame includes a signal field and the second portion of the packet or the frame includes at least one of a long training field and a data portion.

8. The apparatus of claim 6, wherein:

the first portion of the packet or the frame comprises a signal field and the second portion of the packet or the frame comprises at least one of a long training field and a data portion; and

the second down-conversion ratio is relatively higher or larger than the first down-conversion ratio.

9. The apparatus of claim 6, wherein:

the first portion of the packet or the frame includes a first signal field and the second portion of the packet or the frame includes at least one of a long training field, a second signal field, and a data portion.

10. A method for operating a communication device, the method comprising:

operating at least one communication interface of the communication device to receive signals from at least one other communication device; and

processing the signal to extract packets or frames therefrom; and

down-converting a first portion of the packet or the frame with a first down-conversion ratio and down-converting a second portion of the packet or the frame with a second down-conversion ratio to generate a down-converted packet or a down-converted frame.