RU2414060C2 - Method and apparatus for transmitting pilot signal in multi-antenna wireless communication system - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: data transmission signal may be generated and transmitted with a first power level, and a continuous pilot signal containing pilot information relating to the data signal may be generated and transmitted with a second transmission power level lower than the first transmission power level. Alternatively, a discontinuous pilot signal may be generated so that it does not overlap with pilot segments in the first signal, and may be transmitted with a first power level without mutual interference with the first signal as received by a SISO user device. A MIMO user device may receive both signals and may use the pilot signal for better evaluation of the MIMO channel for the first signal.

EFFECT: high quality of pilot information on MIMO user devices without increasing mutual interference of SISO user devices in a wireless communication environment.

49 cl, 12 dwg

Description

This application claims priority according to provisional application No. 60/719999, entitled "METHOD AND DEVICE FOR TRANSMITTING A PILOT SIGNAL IN A MULTIPLE ANTI-WIRELESS COMMUNICATION SYSTEM", filed September 23, 2005; provisional application No. 60/738754, entitled “METHOD AND DEVICE FOR TRANSMITTING A PILOT SIGNAL IN A MULTIPLE ANTI-WIRELESS COMMUNICATION SYSTEM”, filed November 21, 2005, and provisional application No. 60/738213, entitled “A METHOD AND A DEVICE FOR REMOVING USE "filed November 18, 2005, which are assigned to the assignee and incorporated herein by reference.

BACKGROUND

Technical field

The following description relates generally to wireless communications and, in particular, to improving channel estimation in a wireless communications environment.

State of the art

Wireless communication systems have become widespread means by which most people around the world communicate. Wireless devices have become smaller and more powerful to meet consumer needs and improve portability and convenience. The increase in processing power in mobile devices, such as mobile phones, has led to an increase in the requirements for wireless network transmission systems. Such systems are not amenable to such an easy upgrade as the cellular devices operating in them. As the capabilities of mobile devices expand, it may be difficult to maintain an earlier wireless network system in such a way as to fully utilize the new and improved capabilities of wireless devices.

In more detail, frequency division-based technology usually divides the spectrum into separate channels by splitting it into equal fragments of the bandwidth, for example, the division of the frequency band allocated for wireless communication can be carried out into 30 channels, each of which can carry a voice communication session or , in the case of a digital service, transfer digital data. Each channel can be intended for only one user at any given time. One known option is the orthogonal frequency division technique, which effectively partitions the entire system bandwidth into multiple orthogonal subbands. These subbands are also known as tones, carriers, subcarriers, bins, and / or frequency channels. Each subband is associated with a subcarrier that can be modulated with data. In the case of a time-based method, the range is divided in time into consecutive time intervals or time segments. Each channel user is provided with a time period for transmitting or receiving information in a circular manner. For example, at any given time t, the user has access to the channel for a short pulse. Further, access is switched to another user who is given a short burst of time to transmit and receive information. The cycle of "alternation" continues, and ultimately each user is provided with many impulse intervals of transmission and reception.

A code division-based method typically transmits data at several frequencies available at any time in a range. In general, the data is digitized and expanded over the available range, and many users can overlap on one channel, and a unique sequence code can be assigned to the corresponding users. Users can transmit in the same broadband portion of the spectrum, with each user signal being expanded across the entire bandwidth by means of a corresponding unique spreading code. This method can provide sharing in which one or more users can simultaneously transmit and receive. Such sharing can be achieved by spread spectrum digital modulation, wherein the user bitstream is encoded and expanded in a very wide channel in a pseudo-random manner. The receiver is designed to recognize the corresponding unique sequence code and to cancel randomization in order to collect the bits of a specific user in a coherent manner.

A typical wireless communication network (e.g., using frequency, time, and code division techniques) includes one or more base stations that provide coverage, and one or more mobile (e.g., wireless) terminals that can transmit and receive data within coverage area. A typical base station may simultaneously transmit multiple data streams for broadcast, multicast, and / or unicast services, the data stream being a data stream that may be of independent interest for reception on a mobile terminal. A mobile terminal within the coverage area of this base station may be interested in receiving one, more than one or all of the data streams carried by the composite stream. Similarly, a mobile terminal may transmit data to a base station or other mobile terminal. Such communication between the base station and the mobile terminal or between the mobile terminals may be degraded due to channel channel differences and / or interference power differences.

For example, in a wireless communication system, a transmitter (eg, a base station or terminal) may use multiple transmit antennas (T) to transmit data to a receiver equipped with one or more receive antennas (R). Multiple transmit antennas can be used to increase system capacity by transmitting various data from these antennas and / or to increase reliability by transmitting data with redundancy. For example, a transmitter may transmit a given symbol from all T transmit antennas in an encoded manner, and a receiver may receive multiple versions of this symbol through R receive antennas. These many versions of the transmitted character generally improve the receiver's ability to recover the character.

However, certain users may be configured to receive signals transmitted from a single antenna. Therefore, there is a need in the art for systems and methods that facilitate communication and channel estimation by users who are able to communicate using multiple antennas or a single antenna in a substantially transparent manner to the user.

SUMMARY OF THE INVENTION

The following description provides a simplified summary of one or more embodiments to provide a basic understanding of such options. This section is not an extensive overview of all proposed embodiments and is not intended to establish key elements of all options, nor to establish the scope of some or all of the options. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as an introduction to the more detailed description that is presented later.

In accordance with one or more embodiments and their corresponding disclosure, various aspects are described in connection with presenting improved pilot information to multi-input multi-output user devices (MIMOs) without increasing mutual interference of single input / single output (SISO) devices in wireless communication environment. For example, a data signal may be generated and transmitted at a first power level, and a second signal including pilot information associated with a data signal may be generated and sent at a second power level below a first transmit power level. In this scenario, the second signal may be a continuous signal and will not interfere with the first signal due to the transmission of the second signal at a lower power level. In addition, the second signal can be generated as an intermittent signal so that it does not overlap with the pilot segments of the first signal in order to avoid interference with the first signal, as received by the SISO user device, in which case the second signal does not need to be transmitted at a lower power level than data transmission signal. The user MIMO device can receive both signals and can use the second pilot signal to better estimate the channel for the first signal (for example, the user MIMO device can receive both signals at the same time).

According to another aspect, a method for performing pilot transmission in a wireless communication environment may include transmitting a code division multiplexed (CDM) signal, which is continuous, from a first antenna at a base station, and transmitting a second signal containing pilot information related to the CDM signal , from the second antenna at the base station. The CDM signal may include orthogonal frequency division multiplexed (OFDM) pilot segments that are used to estimate the channel for the SISO user device, and the second signal may include OFDM pilot segments that are used to estimate the channel for the MIMO user device. The second signal may be intermittent, and the pilot segments of the second signal may be arranged so that they do not overlap with the pilot segments of the CDM signal. Alternatively, the second signal may be continuous and may be transmitted at a power level approximately 20 dB below the power level at which the CDM signal is transmitted. The method may further include providing a second signal according to a predetermined model, for example, once for every N transmissions of the CDM signal, where N is an integer greater than 1. Moreover, the method may include completing the transmission of the second signal after switching from a low bandwidth modulation format to a format high bandwidth modulations for transmitting a CDM signal, for example, from a quadrature phase modulation (QPSK) format to a 64-bit quadrature amplitude modulation (QAM) format.

According to another aspect, an apparatus that facilitates providing pilot information for channel estimation in a wireless communication environment may include multiple antennas and a processor coupled to multiple antennas, the processor being configured to transmit a CDM signal including OFDM pilot segments from the first antenna for a SISO user device, and a second signal including pilot information related to the CDM signal from the second antenna for the MIMO user device. The processor may generate a CDM signal as a continuous signal including data segments and OFDM pilot segments. The device may further comprise a low power signal generator that generates a second signal as a continuous signal. The processor can transmit the first signal at the first power level and the second signal at the second power level about 20 dB below the first power level. Alternatively, the second signal may be an intermittent signal including OFDM pilot segments that do not overlap with the CDM pilot segments. In this case, the processor can transmit the CDM signal and the second signal at approximately the same power level. The processor may also transmit a second signal according to a predetermined model, for example, once for every N transmissions of the CDM signal, where N is an integer greater than 1, or any other suitable transmission model.

According to another aspect, a wireless communication device may include means for generating a CDM signal including OFDM pilot segments, means for generating an OFDM pilot signal, and means for transmitting a CDM signal from a first antenna and transmitting an OFDM pilot signal from a second antenna. The OFDM pilot may be intermittent and may include pilot segments that do not overlap with pilot segments in the CDM signal. In this case, the device may further comprise means for transmitting the CDM signal and the OFDM pilot signal at a substantially similar power level. Additionally or alternatively, the OFDM pilot may be a continuous signal that includes pilot segments overlapping with the pilot segments in the CDM signal. The device may further include means for transmitting a continuous OFDM pilot signal at a power level of about 20 dB below the CDM signal transmit power level.

A further aspect relates to a computer-readable medium comprising computer-executable instructions stored therein that generate a CDM signal including OFDM pilot segments, generate an OFDM pilot signal including pilot information related to the CDM signal and transmit the CDM signal from the first antenna and transmit simultaneously OFDM signal from the second antenna. The instructions may further include generating the OFDM pilot as an intermittent signal with pilot segments that do not overlap the pilot segments in the CDM signal, and transmitting the OFDM pilot signal and the CDM signal at the same power level. Additionally or alternatively, the instructions may further include generating the OFDM pilot as a continuous signal, including pilot segments that overlap with the CDM signal, and transmitting the OFDM pilot signal at a power level of about 15-25 dB below the transmit power level for the CDM signal.

Another aspect relates to a processor that executes instructions to increase throughput in a wireless communication environment, the instructions comprising generating a CDM signal having pilot segments of the OFDM signal, generating an OFDM pilot signal that has pilot information related to the CDM signal, and transmitting the signal CDM from the first antenna and transmission of the OFDM pilot signal from the second antenna. The instructions further include generating the OFDM pilot as an intermittent signal having continuity gaps between the pilot segments, the continuity gaps being generally aligned with the pilot segments of the CDM signal, and transmitting the intermittent CDM signal and the OFDM pilot signal at approximately the same power level. Additionally or alternatively, the commands may include generating the OFDM pilot as a continuous signal, the pilot segments of which overlap with the pilot segments in the CDM signal, and transmitting the continuous OFDM pilot signal at a power level of about 20 dB below the transmit power level for the CDM signal.

According to yet another aspect, a method for performing pilot transmission in a wireless communication environment may include transmitting a CDM signal having pilot segments at a first transmit power level from a first antenna of a base station, transmitting an OFDM pilot signal including pilot segments related to a CDM signal at a first the transmit power level from the second antenna of the base station, and temporarily reduce the transmit power of the OFDM pilot signal to the second transmit power level during the transmission of the pilot segments in the CDM signal for mensheniya mutual interference between signals. The second transmit power level may be about 20 dB lower than the first transmit power level.

To implement the following and corresponding results, one or more embodiments comprise the features described below and, in particular, set forth in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of one or more embodiments. These aspects, however, point to some of the various ways in which the principles of various embodiments can be used, and the described embodiments are intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

1 illustrates a wireless communication system with multiple base stations and multiple terminals in accordance with one or more aspects.

2 illustrates a multi-input multiple-output (MIMO) channel formed by T transmit antennas of a base station and multiple (R) receive antennas of a terminal in accordance with various aspects described herein.

FIG. 3 illustrates a link structure in accordance with one or more aspects described herein.

4 illustrates a link structure in accordance with one or more aspects described herein.

5 illustrates a link structure in accordance with one or more aspects described herein.

6 illustrates a block diagram of a system that facilitates providing a low power pilot signal in addition to a communication signal in accordance with various aspects.

7 illustrates a methodology for providing improved channel estimation for user MIMO devices without adversely affecting existing SISO users communicating within the same wireless communication environment in accordance with one or more aspects.

8 is an illustration of a methodology for conducting improved channel estimation for user MIMO devices without adversely affecting existing SISO users communicating within the same wireless communication environment in accordance with one or more aspects.

FIG. 9 illustrates a pilot transmission methodology for channel estimation by user MIMO devices without adversely affecting existing SISO users communicating within the same wireless communication environment in accordance with one or more aspects.

10 is an illustration of a user device that facilitates the detection of a low power pilot signal that can be used to estimate a channel for a more powerful communication signal in a wireless communication environment in accordance with one or more aspects set forth herein.

11 is an illustration of a system that facilitates providing a low power pilot signal that can be used to estimate a channel for a more powerful communication signal in a wireless communication environment in accordance with various aspects.

12 is an illustration of a wireless network environment that can be used in conjunction with the various systems and methods described herein.

SUMMARY OF THE INVENTION

Various embodiments are now described with reference to the drawings, in which like reference numerals are used to denote like elements. In the following description, for purposes of explanation, numerous specific details are set forth in order to gain a thorough understanding of one or more embodiments. It is obvious, however, that such embodiment (s) may be practiced without these specific details. In other examples, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.

Used in this application, the terms "component", "system", etc. designed to refer to a computer related object, equipment, software, run-time software, firmware, medium software, microcode, and / or any combination thereof. For example, a component may be, without limitation, a process executable on a processor, an object executed by a program, a thread of execution, a program, and / or a computer. One or more components may be within the process and / or thread of execution, and the component may be located on one computer and / or distributed between two or more computers. Also, these components can be implemented from various computer-readable media having various data structures. Components can communicate through local and / or remote processes, such as in accordance with a signal having one or more data packets (for example, data from one component interacting with another component in a local system, distributed system and / or over a network, such as Internet, with other systems via signal). In addition, the components of the systems described herein can be rearranged and / or supplemented with additional components to facilitate the achievement of various aspects, goals, advantages, etc. described in relation to the described invention, and are not limited to the exact configurations set forth, which will be clear to the specialist.

Moreover, various embodiments are described herein in connection with a subscriber terminal. A subscriber terminal may also be called a system, subscriber unit, mobile station, mobile phone, remote station, access point, remote terminal, access terminal, user terminal, user agent, user device, or user equipment. The subscriber terminal may be a cellular telephone, a radiotelephone, a SIP (Session Initiation Protocol) telephone station, a local wireless communications station (WLL), a personal digital assistant (PDA), a handheld device with wireless connectivity, or another processing device associated with a wireless modem.

In addition, various aspects or characteristics described herein may be implemented as a method, device, or product using standard programming and / or engineering technology. The term “product,” as used herein, is intended to include within its scope a computer program accessible from any computer-readable device, medium, or medium. For example, computer-readable media can include, but are not limited to, magnetic storage devices (e.g., hard disk, floppy disk, magnetic cards, etc.), optical disks (e.g., compact disc (CD), universal digital disc ( DVD), etc.), smart cards and flash memory devices (e.g. card, stick (flash memory card), key drive (portable memory), etc.). Additionally, the various storage media described herein may represent one or more devices and / or other computer-readable storage media. The term “machine-readable medium” may include, without limitation, wireless channels and various other environments capable of storing, containing and / or executing instructions (s) and / or data. The word "typical" is used here to mean "serving as an example, sample, or illustration." Any embodiment or development described herein as “typical” should not necessarily be construed as preferred or advantageous over other embodiments or developments.

1 illustrates a wireless communication system 100 with multiple base stations 110 and multiple terminals 120 in accordance with one or more aspects. A base station is generally a fixed station that communicates with terminals and may also be referred to as an access point, node B, or some other terminology. Each base station 110 provides communication coverage for a specific geographic area 102. The term “cell” may refer to a base station and / or its coverage area depending on the context in which the term is used. To improve system capacity, the coverage area of the base station can be divided into many smaller areas 104a, 104b, and 104c (for example, three smaller areas, according to FIG. 1). Each smaller area can be served by the corresponding base transceiver subsystem (BTS). The term "sector" may refer to the BTS and / or its coverage area depending on the context in which the term is used. For a sectorized cell, BTSs for all sectors are typically aligned within the base station for the cell. The transmission technologies described herein can be used for a system with sectorized cells in the same way as for a system with non-sectorized cells. For simplicity, in this description, the term "base station" is used generally for a fixed station that serves a sector in the same way as for a fixed station that serves a cell.

Terminals 120 are typically dispersed throughout the system, and each terminal may be stationary or mobile. A terminal may also be referred to as a mobile station, user equipment, or defined by some other terminology. The terminal may be a wireless device, a cell phone, a personal digital assistant (PDA), a wireless modem card, etc. Each terminal 120 may communicate with one or a plurality of base stations in the downlink and uplink at any given time or not communicate with any of them. The downlink (or straight line) refers to the communication line from the base stations to the terminals, and the uplink (or reverse line) refers to the communication line from the terminals to the base stations.

For a centralized design, a system controller 130 is connected to base stations 110 and coordinates and controls for base stations 110. For a distributed architecture, base stations 110 can communicate with each other as needed. Data is transmitted in a straight line from one access point to one access terminal at or near the maximum data rate that can be supported by a direct line and / or communication system. Additional forward link channels (eg, control channel) may be transmitted from multiple access points to one access terminal. Reverse link data can be transmitted from one access terminal to one or more access points.

After registration, which allows the access terminal to connect to the access network, the access terminal 120 and one of the access points, such as access point 110, establish a communication line using a predetermined access procedure. In a connection state resulting from a predetermined access procedure, access terminal 120 can receive data and monitor messages from access point 100 and is able to transmit data and monitor messages to access point 100. Access terminal 120 continuously searches for other access points that can be added to the active set of access terminal 120. The active set includes a list of access points capable of communicating with access terminal 120. When such an access point is found, the access terminal 120 may calculate a straight-line quality score of the access point, which may include a signal to interference to noise ratio (SINR). SINR may be determined in accordance with the pilot signal. Access terminal 120 searches for other access points and determines SINRs for the respective access points. At the same time, the access terminal 120 calculates a forward link quality metric for each access point in the active set of the access terminal 120. If the straight line quality metric of a specific access point is above a predetermined upper threshold or below a predetermined lower threshold in a predetermined period of time, access terminal 120 may report such information to access point 110. Subsequent messages from access point 110 may instruct access terminal 120 to add or remove a specific access point from the active set of access terminal 120.

Access terminal 120 may further select a valid access point from the active set of access terminal 120, based on a set of parameters. A valid access point is an access point that is selected for data transmission by a specific access terminal or an access point that transmits data to a specific access terminal. The parameter set may include any or any of the current or past SINR results, for example, bit error rate, packet error rate, and any other known or desired parameters. Thus, for example, a valid access point can be selected according to the largest SINR measurement. Access terminal 120 may then broadcast a data request message (DRC message) over a data request channel (DRC channel). A DRC message may comprise a requested data rate or, alternatively, an indication of the quality of the forward link (e.g., measured SINR, bit error rate, packet error rate, etc.) and the like. Access terminal 120 may direct a DRC message to a specific access point using a code that uniquely identifies a valid access point.

Data to be transmitted to access terminal 120 may be received by access network controller 130. Further, the access network controller 130 may send data to all access points of the active set of the access terminal 120. Alternatively, the access network controller 130 may first determine which access point has been selected by the access terminal 120 as a valid access point, and then send data to the active access point. Data may be queued at the access point (s). The paging message may then be sent by one or more access points to the access terminal 120 via appropriate control channels. Access terminal 120 demodulates and decodes signals on one or more control channels to receive paging messages.

In a straight line, an access point can schedule data transmissions to any of the access terminals that received a paging message. A typical method for scheduling transmission is described in US Pat. No. 6,229,795, entitled "Resource Allocation System in a Communication System", assigned to this assignee. However, other planning techniques may also be used. The access point uses the rate control information received in the DRC message from each access terminal to efficiently transmit forward link data at the highest possible rate. Since the data rate may vary, the communication system operates in a variable speed mode. The access point determines the data rate at which data is transmitted to the access terminal 120 using the most recent DRC value received from the access terminal 120. Additionally, the access point uniquely determines the transmission to the access terminal 120 using an extension code that is unique to this mobile station. However, other technologies may also be used. This distribution code may be a long pseudo-random code (PN), for example, an extension code defined by the IS-856 standard.

The access terminal 120 for which the data packet is intended receives and decodes the data packet. Each data packet is associated with an identifier, such as a sequence number, that is used by access terminal 120 to detect missing or duplicate transmissions. In this case, the access terminal 120 reports the sequence numbers of the skipped data packets through the feedback data channel. The access network controller 130, which receives data messages from the access terminal 120 through an access point communicating with the access terminal 120, then indicates to the access point which data blocks have not been received by the access terminal 120. The access point then schedules the relay of such data packets.

FIG. 2 illustrates a MIMO channel formed by T transmit antennas 304a-304n at base station 302 and a plurality of R receive antennas 306a-306n (where n is an integer) at terminal 308, in accordance with various aspects described herein. The MIMO channel can be characterized by an R × T channel response matrix H (k) for each transmission frequency k in the case of FDMA, a multiple CDMA carrier, a transmitter, or a subband in the case of an OFDM transmitter, which can be described as follows:

(1)

(one)

where h _{j, i} (k) for j = 1, ..., R and i = 1, ..., T denotes the complex channel gain between the transmitting antenna i and the receiving antenna j for each k; and h _i (k) is the R × 1 channel response vector for transmit antenna i, which is the ith column of H ( k ).

In the case of a MIMO system or any SDMA or other multi-antenna system, the receiver and transmitter can evaluate each channel to determine capacitance, speed, and / or power parameters for each channel. This estimate, which may include calculating signal-to-noise and noise ratios, is more complex for a MIMO receiver. In a system with mixed users (for example, both SISO users and MIMO users), some transmission resources may remain unused during transfers to SISO users. However, using other antennas to transmit pilot signals or other control information to MIMO users during SISO transmissions may increase mutual interference and cause decoding errors for the SISO user.

According to one aspect, in the case where system resources are distributed completely to one user at a time, users can be divided in time, moreover, resources are allocated to a given user for a given period of time. In such a scenario, when resources are allocated to SISO users, the transmission rate estimation (DRC) capability can be provided, which can be supported by MIMO users who do not transmit a signal in this interval. In certain embodiments, a low power continuous pilot may be transmitted from some or all of the antennas not transmitting signals to the SISO user for MIMO users. Thus, the ability to evaluate DRC can be provided to MIMO users even when they are not planned.

FIG. 3 illustrates a straight line structure 400 in accordance with one or more aspects described herein. It is important to note that the durations described below, the lengths of the chips, value ranges, etc. presented only as examples, and other time durations, elementary premises lengths, value ranges, etc. can be used without departing from the basic principles of the communication system. The term “chips” defines a signal element with code extension having two possible meanings.

Straight line 400 is defined in terms of frames. A frame is a structure containing time slots 402, with each time slot having, for example, a length of 2048 chips, which corresponds to a time slot of approximately 1.66 ms in duration. Each time interval 402 includes pilot pulses 404. Each pilot pulse 404 may be 96 chips long, centered relative to the midpoint of the corresponding time interval 402. Pilot pulses 404 include a pilot channel signal that is covered or modulated by a code, such as a Walsh code with an index of 0. Direct channel 40 access medium access (MAC) forms four pulses, which are transmitted immediately before and immediately after the pilot pulse 404. MAC 406 can be formed by code channels of up to 64, which can be orthogonally covered with a 64-bit code, such as a Walsh code. Each code channel is identified by a MAC index between 1 and 64, and identifies a unique 64-bit covering (masking) Walsh code. The forward link traffic channel or control channel payload is transmitted in the remaining parts 408 of time slot 402. The traffic channel carries user data, while the control channel carries control messages and can also carry user data.

In order to provide an improved estimate for MIMO users, reducing interference to the SISO user, a pilot signal 410, which may be intermittent, may be transmitted from antennas A2, while signal 402 is transmitted from antenna A1. In this case, the pilot signal 410 includes segments 412, 414 and 416 that do not overlap with all or most of the pilot segments 404 of the signal 402. For example, continuity gaps between the pilot segments 412, 414 and 416 may have a length of about 96 chips and be aligned with the pilot segments 404 of the signal 402. If necessary, the pilot signal 410 can be transmitted at a power level below the power level of the signal 402, such as 20 dB below the transmit power of the signal 402. However, the pilot signal 410 can be transmitted at any desired level power on tea output signal 402 when it is discontinuous (e.g., it can not overlap pilot segments 404 in the signal 402 and thus not be a hindrance). Additionally and / or alternatively, transmission power may be reduced for signal 410 during transmission of pilot segments 404, and pilot MIMO segments 412, 414 and 416 may be transmitted at a lower power level during pilot intervals 404. For example, pilot segments 412, 414 and 416 and / or signal 410 can be continuous and can be transmitted at the same power level as signal 402, while temporal interference between pilot segments 412, 414 and 416 and pilot segments 404 is reduced by reducing the transmit power of signal 410 to P 404 pilot transfer process.

According to another aspect, the signal 410 may be continuous (for example, the signal should not include gaps between segments 412, 414 and 416) and may include data in addition to pilot information. In such cases, signal 410 can be transmitted with a power of about 20 dB less than signal 402 in order to reduce interference with signal 402 and / or pilot segment 404 therein, while still providing sufficient power for channel estimation for MIMO users. It should be noted that other differences in power (for example, 15 dB, 25 dB, 17 dB, etc.) between signals 402 and 410 can also be used.

Importantly, signal 402 may be a code division multiplexed (CDM) signal with pilot segments 404, which are orthogonal frequency division multiplexed pilot (OFDM) segments. Pilot segments 412, 414 and 416 can likewise be orthogonal frequency division multiplexed to have different carrier frequencies compared to pilot segments 404, and can thus be transmitted simultaneously with pilot segments 404 at the same or different power level without interference . It is also important that signal 410 can be transmitted periodically so as not to be consistent with each CDM transmission from antenna A1. For example, signal 410 may occur after each other signal 402, after transmitting a plurality of signals 402, or after any desired gear shift from antenna A1. In addition, signal transmission 410 may vary in response to detected circumstances, such as loading, etc. For example, it may be desirable to decrease or increase the frequency at which signal 410 is transmitted with respect to signal transmission 402 in response to determining that the download parameter has crossed set acceptable threshold level.

It is important to note that less than all segments 412, 414, and 416 can be transmitted from a given antenna with effective blanking of certain segments during a given time from the antenna. In one typical aspect, where there are four transmitting antennas, antenna 1 can transmit 402, antenna 2 can transmit segment 412, antenna 3 can transmit segment 414, and antenna 4 can transmit segment 416 for a given time interval. Additionally, each antenna can transmit more than one, but less than all segments 412, 414, and 416 during a given time interval. The choice of segments 412, 414, and 416 for a given antenna may vary between time intervals or may remain the same. The difference may be based on the characteristics of the channel or some predetermined model, for example, randomization based on a single matrix. The difference may be based on channel characteristics, a mapping scheme, or some predetermined model, for example, randomization based on a single matrix. Further, the display scheme used may be that depicted and described in pending US patent application No. 11 / 261.823, entitled "Method and apparatus for providing antenna diversification in a wireless communication system", which is incorporated herein in its entirety by reference.

FIG. 4 illustrates a forward transmission structure 500 in accordance with one or more aspects described herein. It is important that the durations described below, the lengths of the chips, value ranges, etc. presented only as examples, and other time durations, elementary premises lengths, value ranges, etc. can be used without departure from the basic principles of the communication system. The term "chip" defines a signal element with a code extension having two possible meanings.

4, in order to provide an improved estimate for MIMO users, a pilot signal 510, which may be intermittent, may be transmitted from antenna A2, while a continuous communication signal 502 is transmitted from antenna A1. In this case, the signal 510 includes segments 512, 514 and 516 that do not overlap with all or most of the pilot segments 504 or MAC segments 506 of the signal 502. For example, in the case where the pilot segments 504 are 96 chips long, and segments of the MAC 506 - 64 chips, heterogeneities (e.g. gaps, etc.) between the pilot segments 512, 514 and 516 of the signal 510 can be approximately 224 chips long and can be aligned with the pilot segments 504 and the MAC segments 506 of the signal 502 According to the corresponding example, the gaps The continuity between pilot segments 512, 514 and 516 can vary in length from about 96 chips to about 224 chips. If necessary, pilot 510 can be transmitted at a lower power level than signal 502, such as 20 dB lower than the transmit power of signal 502. However, pilot 510 can be transmitted at any desired power level, including signal power 502 when it is intermittent (for example, it may not overlap the pilot segments 504 and MAC segments 506 in the signal 502 and thus may not interfere with them).

Additionally and / or alternatively, transmission power may be reduced for signal 510 during transmission of pilot segments 504, and pilot segments 512, 514 and 516 may be transmitted at a constant power level during pilot intervals 504. For example, pilot segments 512, 514 and 516 and / or signal 510 can be continuous and can be transmitted at the same power level as signal 502, while interference between pilot segments 512, 514 and 516 and pilot segments 504 is reduced by reducing the transmit power of signal 510 in the process all transmission pilot segments 504.

According to another aspect, the signal 510 may be continuous (for example, the signal should not include gaps between segments 512, 514 and 516) and may include data in addition to pilot information. In such cases, the signal 510 may be transmitted at a power level below the power level of the signal 502 (for example, approximately 20 dB less than the signal 502). In this way, interference with the signal 502 can be reduced, while providing sufficient power for channel estimation for MIMO users. It should be noted that other differences in power (for example, 15 dB, 25 dB, 17 dB, etc.) between signals 502 and 510 can also be used.

Additionally, it is important to note that the signal 502 can be a CDM signal with OFDM pilot segments 504. The pilot segments 512, 514 and 516 can also be OFDM and can thus be transmitted simultaneously with the pilot segments 504 without being an obstacle to them ( for example, pilot segments 504 and 512, 514 and 516 may overlap). It is further important to note that the signal 510 can be transmitted on a periodic basis, which allows not to show an exact match for each CDM transmission from the A1 antenna. For example, transmission of signal 510 may occur after each other transmission of signal 502, after transmission of a plurality of signals 502, or after any desired gear shift from antenna A1. In addition, signal transmission 510 may vary in response to detected parameters, such as download, etc. For example, it may be desirable to decrease or increase the frequency at which signal 510 is transmitted with respect to signal transmission 502 in response to determining that the percentage load parameter crossed the set acceptable threshold level.

It is important to note that less than all segments 512, 514 and 516 can be transmitted from a given antenna with effective blanking of certain segments during a given time from the antenna. In one typical aspect, where there are four transmitting antennas, antenna 1 may transmit signal 502, antenna 2 may transmit segment 512, antenna 3 may transmit segment 514, and antenna 4 may transmit segment 516 for a predetermined time interval. Additionally, each antenna can transmit more than one, but less than all, segments 512, 514 and 516 during a given time interval. The selection of segments 512, 514, and 516 for a given antenna may vary between time intervals or may remain the same. The difference may be based on channel characteristics, a mapping scheme, or some predetermined model, for example, randomization based on a single matrix. Further, the display scheme used may be that depicted and described in pending US patent application No. 11 / 261.823, entitled "Method and apparatus for providing antenna diversification in a wireless communication system", which is incorporated herein in its entirety by reference.

5 illustrates another straight line structure 502, in accordance with one or more aspects described herein. It is important that the durations described below, the lengths of the chips, value ranges, etc. presented only as examples, and other time durations, elementary premises lengths, value ranges, etc. can be used without departure from the basic principles of the communication system. The term "chip" defines a signal element with a code extension having two possible meanings.

5, a CDM signal 550 and a pilot signal 560 can be transmitted over virtual antennas instead of physical antennas, where virtual antennas are a specific combination of physical antennas. The signals transmitted through the physical antennas A1 and A2 are given or arbitrary combinations of signals transmitted through the virtual antennas B1 and B2. In this case, virtual antenna B1 carries signal 550 and virtual antenna B2 carries signal 560. To map virtual antennas B1 and B2 to physical antennas A1 and A2, combiner 570 is used to multiply the signals from the virtual antennas. Certain aspects and embodiments of imaging approaches based on such a combiner 570 that can use a single or orthonormal matrix are depicted and described in US Patent Application No. 11 / 261,823, entitled "Method and apparatus for providing antenna diversification in a wireless communication system", and US Patent Application No. (Attorney No. 050947), entitled "Virtual Antenna Selective Transmission", both of which are incorporated herein by reference in their entirety.

The mapped CDM signal 550 is then transmitted, in some aspects, from all physical antennas at each time interval 502. As you can see, the pilot segments 554 and the MAC segments 556 of the signal 550 are not overlapped by the pilot 560. The data segments 552 of the signal 552 are overlapped time from the same antenna as the 560 pilot signal.

With respect to FIGS. 3, 4 and 5, the transmission of signals 410, 510 and 560 may be suspended and / or terminated under certain circumstances. For example, it may be desirable to suspend or stop the transmission of signals 410, 510 and 560 when the transmission protocol is changed, for example, as after the transition from the QPSK protocol to the 64-QAM protocol, etc. According to this aspect, the transmission of signals 410, 510 and / or 560 may be suspended or stopped after any similar transition from a relatively low bandwidth modulation format to a higher bandwidth modulation format. Thus, signals 410, 510, and 560 should not be transmitted at all interlaces. Further, in some cases, signals 410, 510 and 560 may be sent to each other time interval and blanked out at intermediate time intervals or sent according to some other predetermined model. Additionally, signals 410, 510 and 560 may be transmitted or blanked according to the data rate of the communication signal. For example, when the first signal carries data with very high spectral efficiency, the secondary signal (for example, pilot signal 410, 510, 560 ...) may be turned off.

6 illustrates a block diagram of a system 600 that facilitates providing a low power pilot signal in addition to a communication signal, in accordance with various aspects. System 600 may comprise a base station 602, a single antenna terminal 606x, and multiple antennas terminal 606y. At base station 602, a data processor (TX) 610 receives data for one or more terminals, processes (e.g., encodes, interleaves, displays symbols, etc.) data based on one or more encodings and modulation schemes, and represents modulation symbols. TX data processor 610 typically processes the data for each terminal separately based on the coding and modulation scheme selected for that terminal. TX data processor 610 receives output symbols for each terminal and presents symbols for a single antenna for a SISO terminal, such as terminal 606x, or to multiple antennas for a MIMO user, such as terminal 606y. TX data processor 610 further multiplexes pilot symbols onto a carrier, carriers, or subbands.

The TX spatial processor 620, which may or may not be represented, may also perform the functions described previously. A modulator 622 (Mod) processes the transmission symbols for each transmit antenna (for example, for OFDM, CDMA, or some other modulation technology) and generates signals for that transmit antenna. Each transmitting unit 624 processes (for example, converts to an analog signal, amplifies, filters, and converts with increasing frequency) its pulse output stream and generates a modulated signal. Modulated signals T from transmitter units 624a through 624t are transmitted from antennas T 604a through 604t, respectively.

At each terminal 606, one or a plurality of antennas 612 receive modulated signals transmitted by the base station 602, and each antenna provides a received signal to a corresponding receiving unit 654. Each receiving unit 654 processes (e.g., amplifies, filters, down-converts, digitizes) its received signal and provides the received pulses to the demodulator 656 (Demod). A demodulator 656 processes the received signal for each receive antenna 612, obtains received frequency domain symbols for the sum of K subbands, provides received symbols for the assigned subbands, and provides received pilot symbols for the subbands used for pilot transmission.

For a single antenna terminal 606x, the data detector 66Ox receives the received symbols from the demodulator 656x and extracts channel estimates for the channels based on the received pilot symbols. For the multi-antenna terminal 606y, the receiving spatial processor 66Oy (RX) receives the received symbols from the demodulator 656y and extracts channel estimates based on the received pilot symbols. The 66Oy RX Spatial Processor may use the Minimum Root Mean Square Error (MMSE) method, the Zero Forcing (ZF) method, the Maximum Ratio Combining (MRC) method, the sequential interference cancellation method, or some other receiver processing method. For each terminal, the RX data processor 662 processes (eg, performs symbol mapping, deinterleaving, decoding ...) the detected symbols and provides decoded data to the terminal. In general, the processing by each terminal 606 is complementary to the processing by the base station 602.

Each terminal 606 may generate feedback information for transmitting data to this terminal. For example, each terminal 606 may evaluate SNRs, DRC, CQI, or other information, for example, based on the received pilot symbols. Each terminal 606 may select one or more coding and modulation schemes, one or more packet formats, one or more virtual antennas, to use, for data transmission, one or more orthonormal matrices and so on, based on SNR estimates and / or other information. Each terminal 606 may also generate acknowledgments (ACKs) for correctly received data packets. Feedback information may include SNR estimates, selected coding and modulation schemes, selected virtual antenna (s), selected orthonormal matrix (s), selected subband (s), ACK information used to control power, some other information, or any combination thereof. Feedback information is processed by TX data processor 680, then processed by TX spatial processor 682, if multiple antennas are present, modulated by modulator 684, generated by transmitting unit (s) 654, and transmitted through antenna (s) 612 of base station 602. At the base station 602, modulated signals transmitted by terminals 606x and 606y are received by antennas 604, generated by receiving units 624, and processed by demodulator 640, RX spatial processor 642, and RX data processor 644 to recover information feedback sent by the terminals. Controller / processor 630 uses feedback information to determine the data rate and coding and modulation schemes to transmit data to each terminal, as well as to generate various checks for TX data processor 610 and spatial processor 620. Controllers / microprocessors 630, 67Ox and 67Oy control the control of various processing units at base station 602 and terminals 606x and 606y, respectively. Memory units 632, 672x and 672y store data and program codes used by base station 602 and terminals 606x and 606y, respectively.

The transmission methods described herein may be implemented by various means. For example, these methods may be implemented in hardware, firmware, software, or a combination thereof. To create equipment, the processing units in the transmitter can be implemented within one or more specialized integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), base matrix crystals (FPGAs ), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described here, or combinations thereof. Processing devices at the receiver may also be implemented within one or more ASICs, DSPs, processors, and so on.

7-9 depict methods for providing an OFDM pilot during transmission of a single CDM communication signal having OFDM pilot segments. For example, methods may relate to providing a low power pilot in an FDMA environment, an OFDMA environment, a CDMA environment, a WCDMA environment, a TDMA environment, an SDMA environment, or any other appropriate wireless environment. While, for the purposes of simplicity of explanation, the methods are shown and described as a series of actions, it is important to consider that the methods are not limited to the specified order of actions, since some actions, in accordance with one or more variants of implementation, can be carried out in a different order and / or at the same time as the other actions shown and described here. For example, those skilled in the art will understand that methods can be represented alternatively as a series of interacting states or events, such as a state diagram. In addition, not all illustrated acts may be required to execute methods in accordance with one or more embodiments.

7 illustrates a methodology 700 for implementing improved channel estimation for user MIMO devices without adversely affecting existing SISO users communicating within the same wireless communication environment in accordance with one or more aspects. At step 702, a first CDM transmission signal may be generated, including data segments, OFDM pilot segments, MAC segments, etc., as described with reference to the previous drawings. At 704, an OFDM pilot may be generated so that the pilot does not overlap with the pilot segments of the first transmission signal. Similarly, the pilot signal may be designed to reduce any mutual interference arising between itself and the pilot segments of the first signal.

At step 706, a first transmission signal may be transmitted from the first transmission antenna. Such a transmission can be carried out at a set power level, which can be any suitable power level, as understood by those skilled in the art. At the same time, in step 708, a pilot signal may be transmitted from the second antenna. The power level at which the pilot signal is transmitted may be the same power level at which the first transmission signal is transmitted without interference with the pilot segments in the transmission signal. For example, continuity gaps in the pilot signal may be aligned with pilot segments of the transmission signal to reduce interference between them. Additionally and / or alternatively, the pilot signal may be transmitted at a lower power level than the first transmission signal to help reduce resource consumption in transmitting the pilot signal. Thus, a pilot signal can be received on a user device using the MIMO protocol, in order to thereby contribute to a better channel estimate, without interference with the first transmission signal and its reception by a user device using the SISO protocol in the same communication sector.

It is understood that the transmission of the pilot signal in step 708 does not have to be carried out after each transmission of the first signal in step 706, but may additionally occur on a periodic basis that does not correspond to each CDM transmission in step 706. For example, a pilot signal may be transmitted to at 708, after each other transmission of the first signal, after every third transmission, after transmission of a predetermined number or set of first signals, or any other desired permutation of the CDM signal transmissions. Additionally, the pilot transmission pattern may be changed in accordance with detected and / or monitored constraints such as load and the like.

FIG. 8 is an illustration of a methodology 800 for implementing improved channel estimation for user MIMO devices without adversely affecting existing SISO users communicating within the same wireless communication environment in accordance with one or more aspects. At step 802, a first CDM transmission signal may be generated, including data segments, OFDM pilot segments, MAC segments, etc., as described with reference to the previous drawings. At 804, a separate OFDM pilot may be generated so that the pilot does not overlap with the pilot segments of the first transmission signal. Additionally, a pilot signal may be generated so that the pilot segments in it do not overlap with all or part of the MAC segments in the first communication signal. Similarly, the pilot signal may be designed to reduce mutual interference arising between itself and the pilot segments and the MAC segments of the first signal.

At step 806, a first transmission signal may be transmitted from the first transmitting antenna. Such a transmission can be carried out at a set power level, which can be any suitable power level, as understood by those skilled in the art. At the same time, in step 808, a pilot signal may be transmitted from the second antenna. The power level at which the pilot signal is transmitted in step 808 may be the same power level at which the first transmission signal is transmitted without interference with the pilot segments in the transmission signal. For example, continuity gaps in a pilot signal may be aligned with pilot segments and MAC segments of a transmission signal to reduce interference between them. Additionally and / or alternatively, the pilot signal may be transmitted at a lower power level than the first transmission signal to help reduce resource consumption in transmitting the pilot signal. Thus, a pilot signal can be received on a user device using the MIMO protocol, thereby contributing to a better channel estimate without interference with the first transmission signal and its reception by a user device using the SISO protocol in the same communication sector.

It is clear that the transmission of the pilot signal at step 808 does not have to be carried out after each transmission of the first signal at step 806, but may additionally occur on a periodic basis, which does not correspond to each CDM transmission at step 806. For example, the pilot signal can be transmitted to at 808, after each other transmission of the first signal, after every third transmission, after transmission of a predetermined number or set of first signals, or any other desired permutation of the CDM signal transmissions. Additionally, the pattern with which the pilot signals are transmitted may be changed in accordance with detected and / or controlled constraints, such as load and the like.

9 illustrates a method 900 for piloting for channel estimation by a MIMO device without adversely affecting existing SISO users communicating within the same wireless communication environment in accordance with one or more aspects. At step 902, a CDM transmission signal may be generated and may include data segments, OFDM pilot segments, etc., as described with reference to the previous drawings. The CDM signal may be received by a user SISO device, as well as a MIMO device communicating with, for example, a base station serving a sector in which the devices are located. At 904, a continuous OFDM pilot may be generated. Unlike methods 700 and 800, the pilot signal generated at 904 does not contain gaps or discontinuities in continuity.

In step 906, a CDM signal may be transmitted from the first transmitting antenna at the base station at a first power level. In step 908, a pilot signal may be transmitted from a second antenna at a second power level. For example, the pilot power level may be about 15-25 decibels below the CDM signal power level. In certain examples, the pilot power level may be about 20 decibels below the CDM signal power level. Thus, a pilot signal can be received on a user device using the MIMO protocol, thus contributing to a better channel estimation without interference with the CDM signal and its reception by a user device using the SISO protocol in the same communication sector.

The transmission of the pilot signal may be performed each time a CDM signal is transmitted, but is not limited to a given transmission frequency. Instead, the pilot signal may be transmitted according to a pattern that corresponds, for example, to each other CDM signal transmission, transmission of a group of N CDM signals, where N is an integer, or any other suitable or desirable permutation of the CDM signal transmissions.

Additionally, the frequency with which the pilot signal is transmitted with respect to that CDM signal may vary in accordance with controlled parameters such as load, resource availability, and the like. Moreover, the pilot transmission may be suspended and / or completed after switching from a relatively low bandwidth modulation format to a higher bandwidth modulation format (e.g., from QPSK to 64-QAM, etc.) to reduce mutual interference.

According to a corresponding aspect, the pilot signal may be transmitted at a power level similar to the power level of the CDM signal, except in the case of transmission of the OFDM pilot segments of the CDM signal. Preferably, during such transmission intervals, the transmission power of the pilot signal can be reduced (for example, 20 dB lower than the transmission power of the CDM signal or at some other level) to reduce mutual interference. If there is overlap between the pilot signal and the pilot segments of the CDM signal, mutual interference can be reduced since the pilot segments of the CDM signal are OFDM and thus can occupy the same time period, since they use different carrier frequencies.

It is understood that, in accordance with one or more aspects described herein, conclusions can be made regarding the transmit power level of the pilot signal, the overlap between the pilot segments in the transmission of the pilot signal and the pilot segments and / or MAC segments in the first transmission signal, etc. d. As used here, the term "conclusion" or "conclusion" refers mainly to the process of inference regarding the states of a system, environment, and / or user from a set of observations recorded by events and / or data. The conclusion can be used to establish a special context or action, or it can generate, for example, a probability distribution by state. The conclusion can be probabilistic, that is, the calculation of the probability distribution over states of interest based on accounting for data and events. The output may also relate to methods used to create higher level events from a set of events and / or data. This conclusion leads to the construction of new events and actions from a set of observable events and / or stored event data, regardless of whether events correlate in a short time interval and whether events and data occur from one or more sources of events and data.

According to an example, one or more of the methods presented above may include making conclusions as to whether a low power pilot signal should be transmitted. For example, a decision may be made as to whether one or more user MIMO devices are present in a communications sector in addition to one or more user SISO devices. If there is no MIMO device, a low-power pilot signal should not be transmitted, which can save resources associated with such a transmission, as well as resources associated with attempts by any device to receive and / or demodulate such a transmission. Conversely, if the presence of at least one MIMO device in a sector is established, a low power pilot signal can be transmitted to improve the provision of such pilot information to the MIMO device for improved channel estimation, etc. Since the pilot signal is transmitted at a power level to a large extent lower than the power level of conventional data transmission, the pilot signal can be transmitted cost-effectively, without interference with the data signal.

According to another example, conclusions can be made regarding the corresponding power level at which a low power pilot signal should be transmitted. For example, it can be concluded that a low power pilot signal should be transmitted at a power level within about 10-30 dB below the transmit power level of the data signal in order to conserve system resources and / or reduce interference between the pilot signal and the data signal . According to a corresponding example, it can be determined that the transmission of the pilot signal is about 15-25 dB below the transmit power level of the data signal is desirable. It is important to note that the following examples are illustrative and are not intended to limit the number of conclusions that can be made, or the method by which such conclusions are made, in conjunction with the various embodiments and / or methods described herein.

10 is an illustration of a user device that facilitates the detection of a low power pilot signal that can be used to estimate a channel for a more powerful communication signal in a wireless communication environment in accordance with one or more aspects set forth herein. The user device 1000 comprises a receiver 1002 that receives a signal from, for example, one or more receiving antennas (not shown), and performs normal actions (e.g., filters, amplifies, downconverts, etc.) on the received signal and digitizes processed signal for receiving reports. The receiver 1002 may be, for example, an MMSE receiver or the like. A demodulator 1004 may demodulate and provide received pilot symbols to a processor 1006 for channel estimation. The processor 1006 may be a processor for analyzing information received by the receiver 1002 and / or generating information for transmission by the transmitter 1014, a processor that controls one or more components of the user device 1000, and / or a processor that analyzes the information received by the receiver 1002, generates information for transmission by the transmitter 1014 and controls one or more components of the user device 1000.

The user device 1000 may further comprise a memory 1008 that is coupled to the processor 1006 and which stores information regarding power levels associated with various signals received by the user device 1000, the differences between such power levels, a search table (s) including information related to this and any other relevant information for detecting a low power pilot signal for estimating a channel related to a communication signal in a wireless communication system as described in here. The memory 1008 may further store protocols related to signal detection, channel estimation, etc., so that user device 1000 can use the stored protocols and / or algorithms for channel estimation, etc., as described herein.

Obviously, the storage components (eg, memory blocks) described herein may be either volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. By way of illustration, but not limited to, non-volatile memory can include read-only memory (ROM), programmable read-only memory (PROM), electrically programmable read-only memory (EPROM), electrically erasable read-only memory (EEPROM) or flash memory. Volatile memory may include random access memory (RAM), which operates as an external cache. By way of illustration, but not limited to, RAM is available in many forms, for example, synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), SDRAM double data rate (DDR SDRAM), extended SDRAM (ESDRAM) , SLDRAM, and DRRAM. The memory 1008 of the respective systems and methods is intended to include, without being limited to, these and other corresponding types of memory.

A receiver 1002 is further coupled to a low power pilot detector 1010, which may facilitate the detection of a low power pilot to estimate a channel associated with a data signal. For example, pilot detector 1010 can evaluate whether there is a low power pilot signal in addition to a data signal containing its own pilot signal and / or MAC segments, and can facilitate its reception and / or demodulation to collect information that can be used to estimate the channel for the data signal. User device 1000 further includes a symbol modulator 1012 and a transmitter 1014 that transmits a modulated signal.

11 is an illustration of a system that facilitates providing a low power pilot signal that can be used to estimate a channel for a more powerful communication signal in a wireless communication environment, in accordance with various aspects. System 1100 comprises a base station 1102 with a receiver 1110 that receives signal (s) from one or more user devices 1104 through multiple receive antennas 1106, and a transmitter 1124 that transmits signal (s) to one or more user devices 1104 through transmit antenna 1108. A receiver 1110 may receive information from a receiving antenna 1106 and is operatively coupled to a demodulator 1112 that demodulates received information. The demodulated symbols are analyzed by a processor 1114, which is similar to the processor described above with respect to FIG. 11, and which is connected to a memory 1116 that stores information related to pilot signals, transmit power levels, lookup tables related thereto, and / or any other relevant information related to the implementation of the various actions and functions formulated here. The processor 1114 is further coupled to a low power pilot signal generator 1118, which can generate a pilot signal as described above with reference to the previous drawings. Low power signals can be created with pilot segments that do not overlap with pilot segments when transmitting data. According to another aspect, the low power pilot segments can be designed so that there is no overlap with the pilot data segments, as well as some or all of one or more MAC segments during data transmission. Additionally, low power pilots can be transmitted with a power level of about 20 dB below the data transmission power level. Data transmission and a low power pilot signal may be simultaneously transmitted from separate transmit antennas 1108.

Modulator 1122 may combine the signal for transmission by transmitter 1124 through transmit antenna 1108 to user devices 1104. In this way, base station 1102 can communicate with multiple user devices 1104 so that the SISO user device can receive data transmission and use the pilot segments in it to estimate the channel, while the MIMO user device can receive data transmission as well as low power pilots that can be used to more accurately evaluate data transfer without interfering with the actual data transfer, as is customary in the SISO user device.

12 is an illustration of a wireless communication system 1200. The wireless communication system 1200, for brevity, illustrates one base station and one terminal. However, it is understood that a system may include more than one base station and / or more than one terminal, wherein additional base stations and / or terminals may be implemented in a similar manner or different from the exemplary base station and terminal described below. In addition, it is understood that the base station and / or terminal may use the systems (Figs. 1-5 and 9-10) and / or methods (Figs. 6-8) described herein to facilitate wireless communication between them.

12, in a downlink at an access point 1205, a data processor (TX) 1210 receives, formats, encodes, interleaves, and modulates traffic data (symbol tables) and provides modulated symbols (“data symbols”). A symbol modulator 1215 receives and processes data symbols and pilot symbols and provides a stream of symbols. A symbol modulator 1220 multiplexes the data and pilot symbols and provides them to a transmitting unit 1220 (TMTR). Each transmit symbol may be a data symbol, a pilot symbol, or a signal value of zero. Pilot symbols may be transmitted continuously in each symbol period. Pilot symbols may be frequency division multiplexed (FDM), orthogonal frequency division multiplexed (OFDM), time division multiplexed (TDM), or code division multiplexed (CDM).

The TMTR 1220 receives and converts the symbol stream into one or more analog signals and further generates an analog signal (for example, amplifies, filters, and upconverts) to generate a downlink signal suitable for transmission over a wireless channel. The downlink signal is then transmitted through the antenna 1225 to the terminals. At terminal 1230, an antenna 1235 receives a downlink signal and provides a received signal to a reception unit (RCVR) 1240. The receiving unit 1240 processes (e.g., filters, amplifies, and downconverts) the received signal and digitizes the processed signal to obtain samples. A symbol demodulator 1245 demodulates and provides received pilot symbols to a processor 1250 for channel estimation. The symbol demodulator 1245 further receives a downlink frequency response estimate from the processor 1250, performs demodulation of the data on the received data symbols to obtain data symbol estimates (which are estimates of the transmitted data symbols), and provides symbol estimates to the data processor 1255 RX, which demodulates ( that is, performs symbol mapping back), interleaves and decodes the data symbol estimates to recover the transmitted traffic data. The processing by the symbol demodulator 1245 and the RX processor 1255 is complementary to the processing of the symbol modulator 1215 and TX data processor 1210, respectively, at access point 1205.

In the uplink, TX data processor 1260 processes the data traffic and provides data symbols. A symbol modulator 1265 receives and multiplexes data symbols with pilot symbols, performs modulation, and provides a symbol stream. Transmission unit 1270 then receives and processes the symbol stream to generate an uplink signal, which is transmitted by antenna 1235 to access point 1205.

At access point 1205, an uplink signal from terminal 1230 is received by antenna 1225 and processed by reception unit 1275 to obtain samples. A symbol demodulator 1280 then processes the samples and provides estimates of the received pilot and data symbols for the uplink. An RX data processor 1285 processes data symbol estimates to recover traffic data transmitted by terminal 1230. A processor 1290 performs channel estimation for each active terminal transmitting on the uplink. Multiple terminals may transmit the pilot simultaneously on the uplink on their respective assigned sets of pilot subbands, where the sets of pilot subbands may be interleaved.

Processors 1290 and 1250 control the operation (e.g., manage, coordinate, organize, etc.) of operations at access point 1205 and terminal 1230, respectively. Corresponding processors 1290 and 1250 may be associated with memory units (not shown) that store program codes and data. Processors 1290 and 1250 can also perform calculations to obtain frequency and impulse response estimates for the uplink and downlink, respectively.

For a multiple access system (e.g., FDMA, OFDMA, CDMA, TDMA, etc.), multiple terminals can transmit simultaneously on the uplink. For such a system, pilot subbands may be shared between different terminals. Channel estimation technologies can be used in cases where the pilot subbands for each terminal cover the entire operating frequency band (possibly with the exception of the edge of the band). Such a pilot subband structure would be desirable to obtain frequency diversity for each terminal. The technologies described herein can be implemented by various means. For example, these technologies may be implemented in hardware, software, or a combination thereof. For a hardware implementation, the processing devices used for channel estimation can be implemented on one or more specialized integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), programmable gate arrays (FPGA), microprocessors, controllers, microcontrollers, microprocessors, other electronic components to perform the functions described here, or combinations thereof. Using software, the implementation can be implemented through modules (eg, procedures, functions, and so on) that perform the functions described here. Software codes may be stored in a memory unit and executed by processors 1290 and 1250.

For software implementation, the technologies described here can be implemented by modules (e.g., procedures, functions, etc.) that perform the functions described here. Program codes can be stored in memory blocks and executed by processors. The memory unit may be implemented in a microprocessor or external to the processor, in which case it may be connected to the processor through various means known in the art.

Described above includes examples of one or more embodiments. Of course, it is not possible to describe every conceivable combination of components or methodologies for the purpose of describing the above embodiments, but one skilled in the art will appreciate that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to cover all such modifications and variations that are within the spirit and scope of the appended claims. In addition, in the sense in which the term “includes” is used in the detailed description and in the claims, this term is interpreted as “including”, like the term “comprising”, when the term “comprising” is used as a transition word in the claims .

Claims (49)

1. A method of performing pilot transmission in a wireless communication environment, comprising:
transmitting a code division multiplexed (CDM) signal that is continuous from at least one antenna at a base station; and
transmitting a second signal containing pilot information related to the CDM signal from at least one other antenna at the base station,
moreover, the pilot information in the second signal temporarily overlaps one of the traffic channel information and the control channel information in the CDM signal. 2. The method according to claim 1, in which the second signal includes pilot segments that are used to estimate the channel for a user device with multiple inputs and multiple outputs (MIMO). 3. The method of claim 1, wherein the second signal is an OFDM signal. 4. The method according to claim 3, in which the second signal is intermittent and the pilot segments of the second signal do not overlap the pilot segments of the CDM signal. 5. The method according to claim 3, in which the second signal is discontinuous and the pilot segments of the second signal do not overlap the pilot segments or segments of the medium access channel (MAC) in the CDM signal. 6. The method according to claim 1, wherein said transmission of the second signal includes temporarily interrupting the transmission of the second signal during transmission of the CDM signal. 7. The method according to claim 1, wherein transmitting the second signal includes transmitting a second signal with predetermined temporal relationships with respect to the transmission of the CDM signal. 8. The method according to claim 7, in which the specified transmission of the second signal with predetermined time relationships comprises a single transmission of the second signal for every N transmissions of the CDM signal, where N is an integer greater than 1. 9. The method of claim 1, wherein said transmitting the second signal includes determining whether to transmit the second signal based at least in part on the data rate of the CDM signal. 10. The method of claim 1, wherein said transmitting the second signal includes determining whether to transmit the second signal based at least in part on the spectral efficiency of the CDM signal. 11. The method according to claim 1, further comprising transmitting a second signal with a power level of about 15 to 25 dB below the power level with which the CDM signal is transmitted, where the second signal is a continuous signal. 12. The method according to claim 1, further comprising transmitting a second signal with a power level of about 20 dB below the power level with which the first signal is transmitted, where the second signal is a continuous signal. 13. The method according to claim 1, further comprising completing the transmission of the second signal after switching from a low bandwidth modulation format to a high bandwidth modulation format for transmitting a CDM signal. 14. The method of claim 13, wherein the low bandwidth modulation format is quadrature phase modulation (QPSK) and the high bandwidth format is 64 quadrature amplitude modulation (QAM). 15. The method according to claim 1, in which the first signal contains parts transmitted from at least two antennas in the base station for a given period of time, and the second signal contains parts transmitted from the same at least two antennas in the base station for a given period of time, where the first signal and the second signal are mapped to these at least two antennas according to a linear combination. 16. The method according to clause 15, in which the first signal and the second signal are displayed on these at least two antennas according to the orthonormal matrix. 17. The method according to clause 15, in which the first signal and the second signal are mapped to these at least two antennas, and the first signal and the second signal are mapped to these at least two antennas according to the unit matrix. 18. A wireless communication device comprising a plurality of antennas and a processor coupled to a plurality of antennas, the processor configured to transmit a CDM signal including OFDM pilot segments from at least one antenna for a SISO user device and a second signal including yourself pilot information associated with the CDM signal from at least one other antenna for the MIMO user device. 19. The apparatus of claim 18, wherein the processor generates a CDM signal as a continuous signal including data segments and OFDM pilot segments. 20. The device according to claim 19, in which the second signal is a continuous signal. 21. The device according to claim 20, in which the processor gives instructions for transmitting the first signal at the first power level and the second signal at the second power level about 20 dB below the first power level. 22. The apparatus of claim 18, wherein the first signal is a continuous signal including data segments, OFDM pilot segments, and MAC segments. 23. The apparatus of claim 22, wherein the second signal is an intermittent signal including OFDM pilot segments that do not overlap with the pilot segments of the CDM signal. 24. The device according to p, in which the processor gives instructions for transmitting a second signal with a predetermined time relationship with respect to the transmission of the CDM signal. 25. The device according to p, in which the processor gives instructions for transmitting a second signal once for every N transmissions of the CDM signal, where N is an integer greater than 1. 26. The device according to p, in which the processor gives instructions for displaying the first signal from at least two antennas of the base station during a given period of time and the second signal from the same at least two antennas of the base station during a given time period, where the first signal and the second signal are mapped to at least two antennas according to a linear combination. 27. The device according to p, in which the processor is configured to form a linear combination according to the orthogonal matrix. 28. The device according to p, in which the processor is configured to form a linear combination according to a single matrix. 29. A wireless communications device, comprising:
means for generating a CDM signal including OFDM pilot segments;
means for generating an OFDM pilot signal and
means for transmitting a CDM signal from at least one antenna and transmitting an OFDM pilot signal from at least one other antenna. 30. The device according to clause 29, in which the OFDM pilot is intermittent and includes pilot segments that do not overlap with the pilot segments in the CDM signal. 31. The device according to clause 29, further comprising means for transmitting a CDM signal and an OFDM pilot signal at a substantially similar power level. 32. The device according to clause 29, in which the OFDM pilot signal is a continuous signal, which includes pilot signals that overlap with the pilot segments in the CDM signal. 33. The device according to clause 29, further comprising means for transmitting an OFDM pilot signal with a power level of about 15-25 dB lower than the CDM signal transmit power level. 34. The apparatus of claim 33, further comprising means for transmitting the OFDM pilot signal with a power level of about 20 dB below the CDM signal transmit power level. 35. The device according to clause 29, in which the first signal contains parts transmitted from at least two antennas in the base station for a given period of time, and the second signal contains parts transmitted from the same at least two antennas in the base station for a given period of time, and the device further comprises means for displaying the first and second signals according to a linear combination. 36. The apparatus of claim 35, wherein the display means includes means for displaying according to an orthogonal matrix. 37. The device according to clause 35, in which the means for displaying includes means for displaying according to a unit matrix. 38. A machine-readable medium containing computer-executable instructions stored thereon for:
generating a CDM signal including OFDM pilot segments;
generating an OFDM pilot signal including pilot information related to the CDM signal; and
transmitting a CDM signal from at least one antenna; and simultaneously transmitting an OFDM signal from at least one other antenna. 39. The computer-readable medium of claim 38, wherein the instructions further comprise generating an OFDM pilot as an intermittent signal with pilot segments that do not overlap the pilot segments in the CDM signal. 40. The computer-readable medium of claim 39, wherein the instructions further comprise transmitting an OFDM pilot and a CDM signal at the same power level. 41. The computer-readable medium of claim 38, wherein the instructions further comprise generating an OFDM pilot as a continuous signal comprising pilot segments that overlap with the pilot segments in the CDM signal. 42. The computer-readable medium of claim 41, wherein the instructions further comprise transmitting an OFDM pilot with a power level of about 15-25 dB below the transmit power level for the CDM signal. 43. The computer-readable medium of claim 42, wherein the instructions further comprise transmitting an OFDM pilot with a power level of about 20 dB below the transmit power level for the CDM signal. 44. A processor that executes instructions to increase throughput in a wireless communication environment, the instructions comprising:
generating a CDM signal that contains OFDM pilot segments; generating an OFDM pilot signal that contains pilot information related to the CDM signal; and transmitting the CDM signal from the at least one antenna and transmitting the OFDM pilot signal from the at least one other antenna. 45. The processor of claim 44, wherein the instructions further comprise generating the OFDM pilot as an intermittent signal having discontinuities between the pilot segments, the discontinuities being substantially aligned with the pilot segments in the CDM signal. 46. The processor according to item 45, in which the instructions further comprise transmitting the CDM signal and the OFDM pilot signal at approximately the same power level. 47. The processor of claim 44, wherein the instructions further comprise generating an OFDM pilot as a continuous signal comprising pilot segments that overlap the pilot segments in the CDM signal. 48. The processor of claim 47, wherein the instructions further comprise transmitting an OFDM pilot with a power level of about 15-25 dB lower than the transmit power level for the CDM signal. 49. The processor of claim 47, wherein the instructions further comprise transmitting an OFDM pilot with a power level of about 20 dB below the transmit power level for the CDM signal.

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