MX2008005454A - A method and apparatus for pre-coding frequency division duplexing system - Google Patents

Abstract

Accordingly, a method and apparatus are provided wherein a receiver system selects a pre-coding matrix, comprising eigen-beamforming weights, to use and provides rank value and matrix index associated with the selected matrix to the transmitter system. The transmitter system upon receiving the rank value and matrix index, determine if the matrix associated with the matrix index provided by the receiver system can be used. If not, them transmitter system selects another matrix for determining eigen-beamforming weights.

Description

A METHOD AND APPARATUS FOR DUPLEXION SYSTEM BY DIVISION OF FREQUENCY OF PRE-CODIFICATION FIELD OF THE INVENTION The present invention relates generally to a pre-coding technique, very particularly, the pre-coding for multiple input and multiple input (MIMO) system that uses frequency division duplexing (FDD).

BACKGROUND OF THE INVENTION Wireless communication systems are widely used to provide various types of communication content such as voice, data, etc. These systems can be multiple access systems capable of supporting communication with multiple users by sharing the available system resources (for example, bandwidth and transmission power).

Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and multiple access systems by division of orthogonal frequency (OFDMA). Generally, a wireless multiple access communication system can simultaneously support communication for multiple wireless terminals. Each terminal establishes communication with one or more base stations through transmissions in forward and reverse links. The forward link (or downlink) refers to the communication link of the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link can be established through a single-input-only-output, multiple-input-signal-output or multiple-input-multiple-output (MIMO) system. A MIMO system employs multiple transmit antennas (Nt) and multiple receive antennas (NR) for data transmission. A MIMO channel formed by the Nt transmit antennas and NR receive antennas can be decomposed into Ns independent channels, which are also referred to as spatial channels, where Ns < min. { Nt, NR} . Each of the Ns independent channels corresponds to a dimension. The MIMO system can provide improved performance (for example, higher performance, higher reliability, better spectral efficiency, etc.) if the additional dimensions created by the multiple reception and transmission antennas. A MIMO system supports a time division duplex (TDD) and frequency division duplex (FDD) system. In a TDD system, the forward link and reverse link transmissions are in the same frequency region so that the principle of reciprocity allows the calculation of the forward link channel from the reverse link channel. This enables the access point to extract transmission eigen beam formation gain on the forward link when multiple antennas are available at the access point. However, in a frequency division duplex (FDD) system, the forward and reverse link transmissions are at widely separated frequencies. As a result, the forward link channel and the reverse link channel can vanish independently. A direct consequence is that the calculations of the reverse link channel do not provide instant channel knowledge of the forward link. This problem is also complicated in a system with multiple reception and transmission antennas, also known as MIMO. Therefore, there is a need for a pre-coding method in which the receiver transmits beam vector information on the reverse link and then the transmitter uses this information to transmit data. in the preferred direction to the receiver.

SUMMARY OF THE INVENTION In one embodiment, an apparatus comprises plurality of electronic devices, each of which has a logic, wherein the apparatus is configured to use one or more electronic devices to determine a preferred range value and a Matrix Index. The device is also configured to transmit the range value and the Matrix Index to another electronic device. In a modality, an apparatus comprises a plurality of electronic devices, each with a logic, wherein the apparatus is configured to use one or more electronic devices to receive a message comprising a range value and a matrix index. The apparatus is further configured to determine whether the received array can be used or discarded. A more complete appreciation of all the advantages and scope of the invention can be obtained from the accompanying figures, the description and the appended claims.

BRIEF DESCRIPTION OF THE FIGURES The characteristics, nature, and advantages of the present description will be more apparent from the following detailed description when taken in conjunction with the figures in which similar reference characters are completely identified in a corresponding manner and in which: Figure 1 illustrates a multiple access wireless communication system conforming to one mode; Figure 2 is a block diagram of a communication system; Figure 3 illustrates a process executed by the access terminal; and Figure 4 illustrates a process executed by the access point.

DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, a multiple access wireless communication system according to one embodiment is illustrated. An access point 100 (AP) includes multiple antenna groups, one includes 104 and 106, another includes 108 and 110, and an additional includes 112 and 114. In Figure 1, only two antennas are shown for each antenna group, however, however, a larger or smaller number of antennas may be used for each group of antennas. The access terminal 116 (AT) is in communication with the antennas 112 and 114, where the antennas 112 and 114 transmit information to the access terminal 116 on the forward link 120 and receive information from the access terminal 116 on the reverse link 118. The access terminal 122 is in communication with the antennas 106 and 108, wherein the antennas 106 and 108 transmit information to the access terminal 122 on the forward link 126 and receive information from the access terminal 122 on the reverse link 124. In an FDD system, the communication links 118, 120, 124 and 126 may use a different carrier frequency than that used by the reverse link 118. Each group of antennas and / or the area in which they are designated to establish communication is often referred to as a sector of the access point. In the embodiment, the antenna groups are designed to establish communication with the access terminals in a sector of the areas covered by the access point 100. In communication over forward links 120 and 126, the transmission antennas of the access point 100 use eigen beam-forming weighting in order to improve the spectral efficiency of forward links for the different access terminals 116 and 124. Also, an access point that uses eigen beam-forming weighting to transmit to the randomly dispersed access terminals through its coverage causes less interference to the access terminals in cells neighboring that an access point that transmits through a simple antenna for all its access terminals. An access point may be a fixed station used to establish communication with the terminals and may also be referred to as an access point, a Node B, or some other terminology. An access terminal can also be called a mobile terminal, a user equipment (UE), a wireless communication device, terminal, access terminal or some other terminology. Figure 2 is a block diagram of one mode of a transmitter system 210 (also known as the access point), and a receiver system 250 (also known as an access terminal) in a MIMO 200 system. In the transmitter system 210, the traffic data for a number of data streams is provided from a data source 212 to a transmission data processor (TX) 214. In one embodiment, each data stream is transmitted over a respective transmission antenna. He data processor 214 formats, encodes, and intersperses the traffic data for each data stream based on a particular coding scheme selected for that data stream in order to provide coded data. In some modalities, the processor TX data 214 applies eigen beam-forming weights to the symbols of the data streams using a pre-coding matrix. The data encoded for each data stream can be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and can be used in the receiver system to calculate the channel response. The encoded data and multiplexed pilot for each data stream are modulated afterwards (ie, are mapped into symbols) based on a particular modulation scheme (eg, BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The rate of data transfer, coding, and modulation for each data stream can be determined by means of instructions executed by the processor 230. The modulation symbols for all data streams are then provided to a MIMO TX 220 processor, the which also processes the symbols of modulation (for example, for OFDM). The MIMO TX 220 processor then provides Nt modulation symbol streams to Nt transmitters (TMTR) 222a to 222t. In certain embodiments, the MIMO TX 220 processor applies eigen beam-forming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted. These eigen beam-forming weights are determined using one of a plurality of antennas by means of a layer matrix, which can be recovered from the memory 232. Each transmitter 232 receives and processes a respective symbol stream to provide one or more signals Analogously, and additionally conditions (eg, amplifies, filters and over converts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Nt modulated signals from the transmitters 222a to 222t are then transmitted from the Nt antennas 224a to 224t, respectively. In the receiver system 250, the transmitted modulated signals are received by the NR antennas 252a to 252r and the signal received from each antenna 252 is provided to a respective receiver (RCVR) 254a to 254r. Each receiver 254 conditions (eg, filters, amplifies, and subverts) a respective received signal, digitizes the conditioned signal to provide samples, and further process the samples to provide a corresponding "received" symbol stream. An RX data processor 260 then receives and processes the symbolic NRs received from the receiver NRs 254 based on a particular receiver processing technique to provide approximately Nt "detected" symbol streams. The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to retrieve the traffic data for the data stream. The processing by means of the data processor RX 260 is complementary to that executed by means of the MIMO processor TX 220 and the data processor TX 214 in the transmitter system 210. A processor 270 periodically determines which pre-coding matrix to use (which is analyze later). The processor 270 formulates a reverse link message comprising a matrix index portion and a range value portion. The reverse link message may comprise various types of information in relation to the communication link and / or the received data stream. The reverse link message is then processed by a TX data processor 238, which also receives traffic data for a number of data streams from a data source 236, modulated by means of a modulator 280, conditioned by the transmitters 254a to 254r, and transmitted back to the transmitter system 210. In the transmitter system 210, the modulated signals of the receiver system 250 are received by the antennas 224, conditioned by the receivers 222, demodulated by a demodulator 240, and processed by an RX data processor 242 to extract the reservation link message transmitted by the receiver system 250. The processor 230 then determines which pre-codification matrix to use to determine the beamforming weights eigen, then process the extracted message. Although Figure 2 analyzes a MIMO system, the same system can be applied to a multi-input system, an output where multiple transmit antennas, for example, those in a base station, transmit currents from a symbol to an antenna device simple, for example, a mobile station. Also, a simple output system for single input can be used in the same manner as described with respect to FIG. 2. In a MIMO system that allows pre-coding, a set of pre-coding arrays is used. for beam formation. 2N matrices are generated (N is the number of bits used, for example 6), each matrix is M x L where M is the antenna number and L is the number of layers (also referred to as a range). Each input M x L presents the eigen beam formation weighting used by the transmitter system (also referred to as the access point). Generally, before the deployment of the system, these matrices are calculated and stored in both the access terminal and the access point memory. In one aspect, these matrices can be updated in real time over the time period. Also, an index number is provided to each matrix. When the AT 116 wishes to request the use of a matrix, the AT 116 simply transmits the matrix index. Depending on the system deployed, 6 bits can be used to index the array, thus indexing 64 arrays. It should be noted that the number of bits used for indexing varies based on the desire of the system operator to use more or less than 64 arrays. Figure 3 illustrates a process 300, executed by means of the processor of the AT 270. In block 302, a range that determines the logic is executed by the processor to determine the rank value in order to provide the AP. This range value is determined based on several factors, for example the calculation measurements of channel, the amount of interference or the geometry of the AT 116 (i.e., the number of antennas, arrays of the antennas, etc.) At 304, a matrix that determines the logic is executed by the processor 270 to determine a matrix of pre-coding This matrix is determined based on, for example, the highest bearable spectral efficiency. Both the range value and the pre-coding matrix can also be determined together with each other. For example, the processor cycles through all possible ranges and calculates the possible spectral efficiency based on a particular matrix associated with each range. Then the processor selects the range and matrix that provide the highest spectral efficiency. In block 306, processor 270 executes a message forming logic to generate a message having a matrix index portion (e.g., 6 bits) and a range portion (e.g., 2 bits for 4x4 MIMO). The matrix index portion is used to provide the matrix index associated with the associated matrix. The range portion is used to provide the preferred range value that will be used by the AT. Depending on the deployed system, if a lower range value is used, then the indexes for arrays associated with the lower range value will be so that not all 6 bits of the array index portion are used.

For example, this can be achieved by indexing the pre-coding matrices so that a selected group of arrays will occupy only a 3-bit array index portion for a layer 1. Which means that for layer 1 the range for the Matrix index is 0-2 ** 3-1. If this type of system is deployed, then the AP 100 will first determine the range value and only process those bits that are required to determine the pre-encoding matrix index. In block 308, processor 270 executes the transmission logic to transmit the message formed in block 306 in the reverse link. Figure 4 illustrates a process 400, executed by means of a processor 230 of the AP. In block 402, processor 230 executes a logic for processing the pre-encoding message to process a message received on the reverse link comprising a matrix index portion and a range portion. This message is received periodically, therefore the processing logic of the pre-coding message is executed periodically. In block 404, processor 230 determines whether an appropriate array index and range value were received in the reverse link. Depending on the condition of the medium, the message containing the array index and range value may have been crashed or did not reach the AP properly or was interrupted. Various methods can be used to authenticate that the AP 100 received an appropriate message on the reverse link. If in block 404 it was determined that the message was not authenticated or the array index portion was not authenticated, then in block 406 the AP 100 selects an appropriate precoding matrix. The AP 100 will continue to either use the current array or select a new array if the processor 230 determines that the current array was not valid. Processor 230 may use some predetermined methods / thresholds stored in memory 232 to select an array or randomly select an array from memory 232. However, if it was determined, in block 404, that a message comprising matrix index e Range information was received and authenticated, then, in block 408, processor 230 executes the extraction logic to extract the range information and determines the range value. In block 410, processor 230 executes the message extraction logic to extract the index bits from the pre-encoding array. In a mode, after extracting, demodulate all the bits that make up the array index portion to determine the array index. In another embodiment, processor 230 uses the range value, determined in block 408, to determine the number of bits of the index portion. of matrix to demodulate. For example, if the range value is 1 and all the associated value range matrices 1 can vary from 0 to 3 (for example 00000 to 000011). Therefore, only the bits that are necessary to interpret the high range value, here, are demodulated. 3. In this example, only the two least significant bits of the array index portion would need to be demodulated. Other bits are ignored or used for other diverse purposes, such as providing data. Once the appropriate bits are demodulated and a matrix index is derived, in block 412, the processor 230 executes the matrix use logic to determine whether the matrix associated with the derived matrix index can be used. In a multiple user system, the AP 100 receives pre-coding requests from several users. The AP 100 is provided with predetermined criteria to determine the use of a particular matrix. In one aspect, the AP can determine whether a required array can be used or not based on the current condition of each user. In block 414, if it was determined that the matrix associated with the received array index can not be used, then processor 230 executes the alternate matrix selection logic to select another array for eigen beam formation. Otherwise, in block 416, processor 230 uses the associated matrix with the matrix index extracted for beamforming. The techniques described herein can be executed through various means. For example, these techniques can be executed in hardware, software, or a combination thereof. For a hardware execution, the processing units (for example the processor 230 and 270, the TX and RX processors 214 and 260, and so on) for these techniques may be executed within one or more devices such as application integrated circuits specific (ASIC), digital signal processors (DSP) digital signal processing devices (DSPD), programmable logic devices (PLD), programmable gate array (FPGA), processors, controllers, microcontrollers, microprocessors, other units electronic devices designed to carry out the functions described herein, or a combination thereof. For a software execution, the techniques described herein can be executed with modules (for example, procedures, functions, and so on) performing the functions described herein. The software codes can be stored in memory units (for example, memory 232 and 272 in Figure 2) and executed by processors (for example, controllers 230). The memory unit can be run inside the processor or externally to the processor, in which case it can be communicatively coupled to the processor by various means as is known in the art. The headings are included as a reference and to help locate certain sections. These headings are not intended to limit the scope of the concepts described here, and these concepts may have applicability in other sections throughout the description. The above description of the described embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these modalities will be readily apparent to those skilled in the art and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but it must be accorded the broadest scope consistent with the principles and novel features described herein.

Claims (35)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as a priority: CLAIMS

1. - An apparatus operable in a wireless communication system, the apparatus comprises: means for determining a range value; means for determining a matrix index; and means for transmitting said reverse link message comprising a matrix index and said range value.

2. The apparatus according to claim 1, characterized in that said means for determining said range value comprise means for measuring channel calculations.

3. The apparatus according to claim 1, characterized in that said means for determining said range value comprise means for measuring the amount of interference.

4. The apparatus according to claim 1, characterized in that said means for determining said matrix index comprises means for using said determined range value.

5. The apparatus according to claim 1, characterized in that said means for determining said matrix index comprises means for analyzing each matrix of a plurality of matrices stored in the memory.

6. The apparatus according to claim 1, characterized in that said means for determining said matrix index comprise means for selecting the highest spectral efficiency.

7.- An apparatus operable in a wireless communication system, the apparatus comprises: receiving a range value and a matrix index; extracting a matrix comprising beamforming weighting values using said range value and said matrix index; and determine if said extracted matrix should be used.

8. The apparatus according to claim 7, further comprising means for extracting said array index using said received range value.

9. The apparatus according to claim 7, further comprising means for determine the number of bits to be demodulated in order to determine said matrix index.

10. The apparatus according to claim 9, characterized in that the means for determining the number of bits to demodulate comprise means for analyzing said range value.

11.- A pre-coding method in a wireless communication system, the method comprises: determining a range value; determine a matrix index; and transmitting said reverse link message comprising a matrix index and said range value.

12. The method according to claim 11, characterized in that determining said range value comprises measuring channel calculations.

13. The method according to claim 11, characterized in that determining said range value comprises measuring the amount of interference.

14. The method according to claim 11, characterized in that determining said matrix index comprises using said determined range value.

15. The method according to claim 11, characterized in that determining said Matrix index comprises analyzing each matrix of a plurality of matrices stored in memory.

16. The method according to claim 11, characterized in that determining said matrix index comprises selecting the highest spectral efficiency.

17.- The method of pre-coding in a wireless communication system, the method comprises: receiving a range value and a matrix index; extracting a matrix comprising beam-forming weight values using said range value and said matrix index; and determine if said extracted matrix should be used.

18. The method according to claim 17, further comprising extracting said array index using said received range value.

19. The method according to claim 17, further comprising determining the number of bits to demodulate in order to determine said array index.

20. The method according to claim 19, characterized in that determining the number of bits to demodulate comprises analyzing said range value.

21. In a wireless communication, an apparatus comprising: a processor, said processor configured to determine a range value; said processor further configured to determine a matrix index; and said processor further configured to transmit said reverse link message comprising a matrix index and said range value.

22. The apparatus according to claim 21, characterized in that said processor further configured to measure the channel calculations wherein said measured channel calculations are used to determine the range value.

23. The apparatus according to claim 21, characterized in that said processor further configured to measure the amount of interference wherein said measured channel calculations are used to determine the range value.

24. The apparatus according to claim 21, characterized in that said processor further configured to use said determined range value to determine said matrix index.

25. The apparatus according to claim 21, characterized in that said processor further configured to analyze each matrix of a plurality of arrays stored in the memory to determine said array index.

26. The apparatus according to claim 21, characterized in that said processor further configured to select the highest spectral efficiency to determine said matrix index.

27. In a wireless communication, an apparatus comprising: a processor, said processor configured to receive a range value and a matrix index; said processor further configured to extract a matrix comprising values of beamforming weights using said range value and said array index; and said processor further configured to determine if said extracted matrix should be used.

28. The apparatus according to claim 27, characterized in that said processor further configured to extract said matrix index using said received range value.

29. The apparatus according to claim 27, characterized in that said processor further configured to determine the number of bits to demodulate in order to determine said matrix index.

30. The apparatus according to claim 29, characterized in that said processor further configured to analyze said range value to determine the number of bits to be demodulated.

31.- A machine-readable medium that comprises instructions which, when executed by a machine, cause the machine to carry out operations that include: means to determine a range value; means for determining a matrix index; and means for transmitting said reverse link message comprising a matrix index and said range value.

32. The machine-readable medium according to claim 31, characterized in that said means for determining said matrix index comprise means for using said determined range value.

33. The machine-readable medium according to claim 31, characterized in that said means for determining said matrix index comprises means for analyzing each nuance of a plurality of matrices stored in the memory. 34.- A device operable in a wireless communication system, the apparatus comprises: receiving a range value and a matrix index; extracting a matrix comprising beamforming weighting values using said value of range and said matrix index; and determine if said extracted matrix should be used. 35.- The machine-readable medium according to claim 34, characterized in that the means for determining the number of bits to demodulate comprise means for analyzing said range value.