Abstract: An apparatus and method for transmitting in a multi-user multi-antenna system are provided. The apparatus includes a precoder for orthogonalizing a channel by removing a channel element of a corresponding terminal with respect to multiple terminals, for determining an effective channel of each terminal by decomposing the orthogonalized channel using Singular Value Decomposition (SVD), for determining a precoding matrix using the effective channel, and for mapping data streams of the multiple terminals to a plurality of transmit antennas using the precoding matrix, and the plurality of the transmit antennas for transmitting the data streams of the multiple terminals. Hence, it is possible to obtain an iteration algorithm performance requiring considerable computation while avoiding complexity and reducing computation.

Abstract: A method and apparatus is provided for determining a modulation and coding scheme in a Multiple Input Multiple Output system with a Maximum Likelihood Detector (MIMO-MLD), in which an upper bound and a lower bound of a Signal to Noise Ratio (SNR) for the MIMO-MLD are determined, an effective Signal to Noise Ratio (eSNR) is computed using a relation between the upper bound and the lower bound, a channel quality is estimated using the eSNR, and a modulation and coding scheme is determined using the estimated channel quality.

Abstract: An achievable sum data rate with respect to each of available candidate transmission/reception modes may be calculated to select a transmission/reception mode of transmission/reception pairs repeatedly using radio resources. A transmission/reception mode to be applied may be selected from the candidate transmission/reception modes based on the calculated sum data rate. Information associated with the selected transmission/reception mode may be shared by the transmission/reception pairs.

Abstract: There is provided a method of determining a Modulation and Coding Scheme (MCS). The method includes predicting an error rate of a symbol and determining a MCS of the symbol using the error rate. Since a MCS level is determined using an estimated error rate and user data is scheduled, multi-user diversity gain can be obtained and the transmission rate can be improved.

Abstract: Methods and apparatus for spatial multiplexing in a closed-loop Multi Input Multi Output (MIMO) system are provided. In a method of operating a receiver in an MIMO system, a signal transmitted by a transmitter is received. Blockwise-Orthogonalized Spatial Multiplexing (B-OSM) is performed on the received signal. Feedback information determined by performing the B-OSM on the received signal is fed back to the transmitter.

Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) modulation. Space-Time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. OFDM modulation allows for wideband transmission over frequency selective radio channels. A receiver demodulates the OFDM signal and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values.

Abstract: A maximum a posteriori (MAP) processor employs a block processing technique for the MAP algorithm to provide a parallel architecture that allows for multiple word memory read/write processing and voltage scaling of a given circuit implementation. The block processing technique forms a merged trellis with states having modified branch inputs to provide the parallel structure. When block processing occurs, the trellis may be modified to show transitions from the oldest state at time k?N to the present state at time k. For the merged trellis, the number of states remains the same, but each state receives 2N input transitions instead of the two input transitions. Branch metrics associated with the transitions in the merged trellis are cumulative, and are employed for the update process of forward and backward probabilities by the MAP algorithm.

Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with modulating several streams of the BICM encoded data for transmission over two or more antennas. Space-time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. A receiver demodulates the received signals and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values. By applying well-known turbo-decoding principles to iteratively demap and decode, the overall receiver performance is significantly improved.

Abstract: A maximum a posteriori (MAP) detector/decoder employs an algorithm that computes log-likelihood value with an a posteriori probability (APP) value employing a number N of previous state sequences greater than or equal to two (N≧2). By defining the APP with more previous state sequences, the set of &agr; values may be calculated for a current state and then reduced. After generating the reduced set of &agr; values, the full set of &bgr; values may be generated for calculation of log-likelihood values. By calculating a set of &agr; values that may be decimated by, for example, N, the amount of memory required to store the &agr; values used in subsequent computations is reduced.

Abstract: An iterative decoding system for intersymbol interference (ISI) channels has a module for extracting bit reliabilities from a partial response (PR) channel, an iterative decoder, and a module for updating the bit reliabilities. A transmitter parses a data sequence into blocks that are encoded to generate a sequence of codewords. By encoding, a correlation among the bits of each codeword output to the PR channel is created. A maximum likelihood sequence detector (MLSD) in the receiver produces estimates of transmitted bits from samples of the output from the PR channel. The MLSD detector has a priori knowledge of typical error events that can occur during transmission through the channel. Along with the bit estimates, at each time instant the MLSD detector generates set of error event likelihoods.

Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with modulating several streams of the BICM encoded data for transmission over two or more antennas. Space-time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. A receiver demodulates the received signals and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values. By applying well-known turbo-decoding principles to iteratively demap and decode, the overall receiver performance is significantly improved.

Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) modulation. Space-Time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. OFDM modulation allows for wideband transmission over frequency selective radio channels. A receiver demodulates the OFDM signal and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values.

Abstract: A maximum a posteriori (MAP) processor employs a block processing technique for the MAP algorithm to provide a parallel architecture that allows for multiple word memory read/write processing and voltage scaling of a given circuit implementation. The block processing technique forms a merged trellis with states having modified branch inputs to provide the parallel structure. When block processing occurs, the trellis may be modified to show transitions from the oldest state at time k−N to the present state at time k. For the merged trellis, the number of states remains the same, but each state receives 2N input transitions instead of the two input transitions. Branch metrics associated with the transitions in the merged trellis are cumulative, and are employed for the update process of forward and backward probabilities by the MAP algorithm.

Abstract: The present invention is a method and system for generating soft outputs by taking advantage of the fact that, in PR channels, there exists a set of error event sequences that occurs more often than others. This results in a soft output extractor with significantly lower complexity than the prior art SOVA system. Minimum distance error event sequences are identified and soft information or bit reliabilities are extracted from the PR channel based on the identified sequences. The soft information is then used by an iterative error control decoder correct errors more efficiently.

Abstract: An iterative decoder employs detection and post-processing of channel output samples to generate soft output vales for encoded data provided to the decoder for one or more iterations of decoding. The channel output samples account for user data encoded with concatenated codes. For one or more other iterations, the reliability values of the soft values of the prior iteration are updated, generating soft output data for the decoder for the current iteration of decoding. A detector may use a soft-output Viterbi algorithm (SOVA) to detect encoded data from channel output samples, and the SOVA algorithm may be implemented by a Viterbi algorithm generating hard decisions from the output channel samples followed by post-processing to generate and update reliability values for the soft-output values based on the hard decisions and output channel samples.

Abstract: A data transmission system employs an iterative decoder that applies decision feedback equalization (DFE) to channel output samples of a packet of data. The iterative decoder receives a stream of channel output samples as packets that may, for example, be read from a sector of a recording medium. Each packet may represent user data encoded, for example, with a concatenated code formed from N component codes, N a positive integer. The iterative decoder employs I decoding iterations, I a positive integer. DFE employs two filters: a feedforward filter and a feedback filter. The feedforward filter, which may be a whitened-matched filter used for detection, shifts dispersed channel output energy into the current sample. The feedback filter cancels energy of trailing inter-symbol interference from previous symbols.

Abstract: A maximum a posteriori (MAP) detector/decoder employs an algorithm that computes log-likelihood value with an a posteriori probability (APP) value employing a number N of previous state sequences greater than or equal to two (N≧2). By defining the APP with more previous state sequences, the set of &agr; values may be calculated for a current state and then reduced. After generating the reduced set of &agr; values, the full set of &bgr; values may be generated for calculation of log-likelihood values. By calculating a set of &agr; values that may be decimated by, for example, N, the amount of memory required to store the &agr; values used in subsequent computations is reduced.

Abstract: An iterative decoding system for intersymbol interference (ISI) channels has a module for extracting bit reliabilities from a partial response (PR) channel, an iterative decoder, and a module for updating the bit reliabilities. A transmitter parses a data sequence into blocks that are encoded to generate a sequence of codewords. By encoding, a correlation among the bits of each codeword output to the PR channel is created. A maximum likelihood sequence detector (MLSD) in the receiver produces estimates of transmitted bits from samples of the output from the PR channel. The MLSD detector has a priori knowledge of typical error events that can occur during transmission through the channel. Along with the bit estimates, at each time instant the MLSD detector generates set of error event likelihoods.

Abstract: A data recording system employs parallel iterative decoding of soft output samples representing encoded data read from a storage medium. The iterative decoder reads packets of data from a sector of the medium, each packet containing soft output samples representing data encoded with a concatenated code formed from N component codes, N a positive integer. The iterative decoder employs I decoding iterations, I a positive integer. Each packet has a length substantially equal to the sector length divided by N. For an exemplary magnetic recording system, encoded data read from a sector of a magnetic medium is partitioned into N packets of length 4096/N. The first packet is passed to the first component code decoder of a parallel iterative decoder. When the second packet is ready to be passed to the first component code decoder, the decoded output values of the first packet in the first decoder are passed to the second component code decoder. The second packet is then applied to the first component code decoder.

Abstract: An iterative decoder arranges calculation of updated reliability values for a current iteration of an iterative decoder so as to reduce the number of comparison operations. The variables for the magnitude and sign of the updated reliability value are initialized. A search of the previous reliability values generates first and second minimum magnitude values for each row (if the iterative decoder is decoding in the horizontal direction) or column (if the iterative decoder is decoding in the vertical direction). A test determines whether the magnitude of the previous reliability value is greater than the first minimum magnitude value m1. If so, the magnitude of the updated reliability value is set as the value m1. Otherwise, the magnitude of the updated reliability value is set as the second minimum magnitude value m2. The sign of the updated reliability value is tracked and assigned once the updated reliability value is set.