摘要:
Techniques to schedule terminals for data transmission on the downlink and/or uplink in a MIMO-OFDM system based on the spatial and/or frequency “signatures” of the terminals. A scheduler forms one or more sets of terminals for possible (downlink or uplink) data transmission for each of a number of frequency bands. One or more sub-hypotheses may further be formed for each hypothesis, with each sub-hypothesis corresponding to (1) specific assignments of transmit antennas to the terminal(s) in the hypothesis (for the downlink) or (2) a specific order for processing the uplink data transmissions from the terminal(s) (for the uplink). The performance of each sub-hypothesis is then evaluated (e.g., based on one or more performance metrics). One sub-hypothesis is then selected for each frequency band based on the evaluated performance, and the one or more terminals in each selected sub-hypothesis are then scheduled for data transmission on the corresponding frequency band.
摘要:
Techniques for performing detection and decoding at a receiver are described. In one scheme, the receiver obtains R received symbol streams for M data streams transmitted by a transmitter, performs receiver spatial processing on the received symbols to obtain detected symbols, performs log-likelihood ratio (LLR) computation independently for each of D best data streams, and performs LLR computation jointly for the M−D remaining data streams, where M>D≧1 and M>1. The D best data streams may be selected based on SNR and/or other criteria. In another scheme, the receiver performs LLR computation independently for each of the D best data streams, performs LLR computation jointly for the M−D remaining data streams, and reduces the number of hypotheses to consider for the joint LLR computation by performing a search for candidate hypotheses using list sphere detection, Markov chain Monte Carlo, or some other search technique.
摘要:
Techniques for performing phase correction for wireless communication are described. Received pilot symbols and received data symbols may be obtained from an orthogonal frequency division multiplexing (OFDM) and/or multiple-input multiple-output (MIMO) transmission. First phase information is obtained based upon the received pilot symbols. Second phase information is obtained based upon the received data symbols. The phase of the received data symbols is corrected based upon the first and second phase information (directly and/or indirectly). For example, the phase of the received data symbols may be corrected based upon the first phase information, detection may be performed on the phase corrected data symbols to obtain estimated data symbols, the second phase information may be obtained based upon the estimated data symbols, and the phase of the estimated data symbols may be corrected based upon the second phase information. The phase correction may also be performed in other manners.
摘要:
Techniques to transmit data on a number of transmission channels in a multi-channel communication system using multiple transmission schemes requiring less channel-state information (CSI). These schemes may include a partial-CSI transmission scheme that transmits a single data stream on each transmit antenna selected for use and a “beam-forming” transmission scheme that allocates all transmit power to a single transmission channel having the best performance. Each transmission scheme may provide good or near-optimum performance for a specific range of operating conditions (or operating SNRs). These multiple transmission schemes may then be combined in a piece-wise fashion to form a “multi-mode” transmission scheme that covers the full range of operating conditions supported by the MIMO system. The specific transmission scheme to be used for data transmission at any given moment would then be dependent on the specific operating condition experienced by the system at that moment.
摘要:
A receiving entity obtains received symbols for a data transmission having at least one data symbol stream sent with space-time transmit diversity (STTD). The receiving entity derives an overall channel response matrix in accordance with the STTD encoding scheme used for the data transmission, derives a spatial filter matrix based on the overall channel response matrix, and performs spatial matched filtering on a vector of received symbols for each 2-symbol interval to obtain a vector of detected symbols for the 2-symbol interval. The receiving entity may perform post-processing (e.g., conjugation) on the detected symbols if needed. Alternatively, the receiving entity derives a spatial filter matrix based on an effective channel response matrix, performs spatial matched filtering on the received symbols for each symbol period to obtain detected symbols for that symbol period, and combines multiple estimates obtained for each data symbol sent with STTD.
摘要:
An access point in a multi-antenna system broadcasts data using spatial spreading to randomize an “effective” channel observed by each user terminal for each block of data symbols broadcast by the access point. At the access point, data is coded, interleaved, and modulated to obtain ND data symbol blocks to be broadcast in NM transmission spans, where ND≧1 and NM>1. The ND data symbol blocks are partitioned into NM data symbol subblocks, one subblock for each transmission span. A steering matrix is selected (e.g., in a deterministic or pseudo-random manner from among a set of L steering matrices) for each subblock. Each data symbol subblock is spatially processed with the steering matrix selected for that subblock to obtain transmit symbols, which are further processed and broadcast via NT transmit antennas and in one transmission span to user terminals within a broadcast coverage area.
摘要翻译:多天线系统中的接入点使用空间扩展广播数据,以随机化由接入点广播的每个数据符号块由每个用户终端观察到的“有效”信道。 在接入点,对数据进行编码,交织和调制,以获得要在N N个传输跨度中广播的N个D个数据符号块,其中N < / SUB >> = 1和N&lt; 1&gt; 1。 N N个数据符号块被划分为N个M个数据符号子块,每个传输跨度的一个子块。 对于每个子块,选择导向矩阵(例如,从一组L个导引矩阵中以确定性或伪随机方式)。 利用为该子块选择的导引矩阵来对每个数据符号子块进行空间处理,以获得发射符号,其进一步经由N T T个发射天线处理和广播,并且在一个传输跨度内广播覆盖范围内的用户终端 区。
摘要:
In one aspect of a multiple-access OFDM-CDMA system, the data spreading is performed in the frequency domain by spreading each data stream with a respective spreading code selected from a set of available spreading codes. To support multiple access, system resources may be allocated and de-allocated to users (e.g., spreading codes may be assigned to users as needed, and transmit power may be allocated to users). Variable rate data for each user may be supported via a combination of spreading adjustment and transmit power scaling. Interference control techniques are also provided to improve system performance via power control of the downlink and/or uplink transmissions to achieve the desired level of performance while minimizing interference. A pilot may be transmitted by each transmitter unit to assist the receiver units perform acquisition, timing synchronization, carrier recovery, handoff, channel estimation, coherent data demodulation, and so on.
摘要:
Techniques for decomposing matrices using Jacobi rotation are described. Multiple iterations of Jacobi rotation are performed on a first matrix of complex values with multiple Jacobi rotation matrices of complex values to zero out the off-diagonal elements in the first matrix. For each iteration, a submatrix may be formed based on the first matrix and decomposed to obtain eigenvectors for the submatrix, and a Jacobi rotation matrix may be formed with the eigenvectors and used to update the first matrix. A second matrix of complex values, which contains orthogonal vectors, is derived based on the Jacobi rotation matrices. For eigenvalue decomposition, a third matrix of eigenvalues may be derived based on the Jacobi rotation matrices. For singular value decomposition, a fourth matrix with left singular vectors and a matrix of singular values may be derived based on the Jacobi rotation matrices.
摘要:
For eigenvalue decomposition, a first set of at least one variable is derived based on a first matrix being decomposed and using Coordinate Rotational Digital Computer (CORDIC) computation. A second set of at least one variable is derived based on the first matrix and using a look-up table. A second matrix of eigenvectors of the first matrix is then derived based on the first and second variable sets. To derive the first variable set, CORDIC computation is performed on an element of the first matrix to determine the magnitude and phase of this element, and CORDIC computation is performed on the phase to determine the sine and cosine of this element. To derive the second variable set, intermediate quantities are derived based on the first matrix and used to access the look-up table.
摘要:
Techniques for transmitting data from a transmitter unit to a receiver unit in a multiple-input multiple-output (MIMO) communication system. In one method, at the receiver unit, a number of signals are received via a number of receive antennas, with the received signal from each receive antenna comprising a combination of one or more signals transmitted from the transmitter unit. The received signals are processed to derive channel state information (CSI) indicative of characteristics of a number of transmission channels used for data transmission. The CSI is transmitted back to the transmitter unit. At the transmitter unit, the CSI from the receiver unit is received and data for transmission to the receiver unit is processed based on the received CSI.