Abstract: A receiver for receiving a layer-modulated signal includes: a base layer decoding unit configured to calculate a bit metric including code bit information of a base layer based on the reception signal and decode an information bit of the base layer; and at least one enhancement layer decoding unit configured to decode an information bit of an upper layer of a lower layer based on the decoding results of the lower layer, wherein the base layer decoding unit and the at least one enhancement layer decoding unit are sequentially connected according to the order of the corresponding layers.

Abstract: According to the teachings presented herein, a method and apparatus provide a reduced search space for blindly decoding a message included in a signal received at a communication receiver, where the message has an unknown format. Improving blind detection efficiency in this manner offers numerous advantages, including but not limited to lower power consumption through reduced processing overhead, and lower power consumption through expanded sleep opportunities. As a non-limiting example, the communication receiver comprises a mobile station configured for operation according to Long Term Evolution (LTE) standards, as promulgated by the 3GPP for E-UTRA systems, where the mobile station is configured to reduce a search space of DCI message decoding by determining message format likelihoods and blindly decoding a received DCI message based on the message format likelihoods.

Abstract: Co-channel communications methods, systems, and devices are provided. Embodiments can be utilized to allow multiple users on one time slot (MUROS). For example, a method for wireless communication by a first remote station can comprise receiving a first co-channel signal that has a first amplitude and a second co-channel signal that has a second amplitude, wherein a difference between the first amplitude and the second amplitude is less than a threshold; selecting one of the first co-channel signal and the second co-channel signal; and demodulating the selected co-channel signal. Other aspects, embodiments, and features are also claimed and described.

Abstract: Maximum likelihood bit-stream generation and detection techniques are provided using the M-algorithm and Infinite Impulse Response (IIR) filtering. The M-Algorithm is applied to a target input signal X to perform Maximum Likelihood Sequence Estimation on the target input signal X to produce a digital bit stream B, such that after filtering by an IIR filter, the produced digital stream Y produces an error signal satisfying one or more predefined requirements. The predefined requirements comprise, for example, a substantially minimum error. In an exemplary bit detection implementation, the target input signal X comprises an observed analog signal and the produced digital stream Y comprises a digitized output of a receive channel corresponding to a transmitted bit stream. In an exemplary bit stream generation implementation, the target input signal X comprises a desired transmit signal and the produced digital stream Y comprises an estimate of the desired transmit signal.

Abstract: Provided are a reception device, a reception method, and a computer program that are capable of high-precision channel estimation using little memory volume. Parameters indicating channel characteristics are estimated from channel estimation values for received signal reference signals; a prescribed coefficient matrix is selected in accordance with the estimated parameters, from among coefficient matrices stored beforehand, said matrix being a coefficient matrix in accordance with a reference signal pattern expanded in the frequency direction; and LMMSE channel estimation is performed using a coefficient included in a range that is a coefficient range arranged in the selected coefficient matrix and corresponds to the received signal reference signal arrangement.

Abstract: Provided is a maximum likelihood decoding method that includes the steps of; firstly arranging channel impulse responses corresponding to the received signals in a plurality of different orders; secondly specifying the same number of parts as the plurality of different orders in which the channel impulse responses are arranged, so that the received signals are placed in each of the parts; thirdly generating channel matrices each having the channel impulse responses as matrix elements, by using the channel impulse responses arranged in the plurality of different orders, obtaining triangular matrices by applying QR decomposition to the generated channel matrices, and determining at least one combination candidate for each of the parts of the plurality of transmission signals by using the obtained triangular matrices; and fourthly selecting the combination candidates so that a Euclidean distance between the combination candidates determined in the third step is shortest.

Abstract: A hybrid equalization system includes an equalization device, a target channel impulse response device, a maximum likelihood sequence estimation device and a multiplexer. The equalization device receives a sampled baseband signal and performs an equalization operation thereon for generating first estimated symbols. The target channel impulse response device convolutes the first estimated symbol and a predetermined target channel response function for generating a training symbol corresponding to a target channel. The maximum likelihood sequence estimation device performs a maximum likelihood sequence estimation on the sampled baseband signal trained by first estimated symbols based on the target channel impulse response for generating second estimated symbols. The multiplexer selects the first estimated symbol or the second estimated symbol as an output of the hybrid equalization system according to a selection signal.

Abstract: A MIMO detector for use in MIMO-OFDM wireless communication that forms a plurality of propagation paths by using a plurality of transmitting and receiving antennas includes: an inverse matrix calculator operating as an inverse matrix calculation unit configured to calculate an inverse matrix of a matrix of the propagation path based on a signal received by a receiver; a detection speed controller operating as an estimation unit configured to estimate a variation in the propagation path over time; and a phase synchronization circuit and a regulator configured to variably control a processing time required to calculate the inverse matrix by the inverse matrix calculator, according to the variation in the propagation path over time estimated by the detection speed controller. The MIMO detector is provided on the side of the receiver of the wireless communication.

Abstract: Iterative demapper. Demodulation and/or demapping of a signal (e.g., based on a constellation whose points have a corresponding mapping with associated labels) is performed such that each dimension is processed separately without accounting for influences from the other dimension. For example, the demapping process operates on each respective dimension separately and independently. In some instances, the processing operates iteratively, in that, information identified from processing one of the dimensions is employed in directing the processing in another of the dimensions. Such operation may be performed iteratively by updating/modified information associated with one or more of the dimensions as well. Moreover, decoding may operate in accordance with iterative demapping (e.g., error correction code (ECC) and/or forward error correction (FEC) code by which information bits are encoded) to make estimates of bits within a signal sequence, and those estimates may be used in a subsequent iteration of demapping.

Abstract: Disclosed are a method for demodulating received signals and an apparatus therefore which can maintain quality of signals and can reduce computational complexity. A demodulation method of a receiving device for receiving a plurality of signals modulated through a M-ary (M is a natural number of 1 or more) modulation method includes: comparing channel frequency response power of a first channel with channel frequency response power of a second channel, selecting M reference signals on the basis of the compared result, selecting corresponding signals paired with respective selected M reference signals, and estimating transmitting signals from the M signal pairs including pairs of the reference signal and the corresponding signal. Accordingly, the computational complexity is reduced from O (M2) to O (M).

Abstract: Embodiments of the invention provide a method of decoding of hexagonal constellations. The decoding methods exploit the inherent structure of the hexagonal grid to eliminate/minimize the requirements for distance computations. A constellation which has unused constellation points is received. A plurality of lookup tables is used for indicating whether a particular constellation point is used. The lookup tables are indexed using the two integers u and v. An initial estimate of u and v is found. The euclidean distance to an immediate four neighbors resulting in the immediate upper and lower integers for ? and v. The upper or lower integer that corresponds to the smalling distance is selected and all other immediate neighbors are computed. Assignment of constellation points on the hexagonal grid for a given constellation size is provided which exploits the inherent redundancy provided by the hexagonal grid.

Abstract: A system and methods that accommodate for nonlinear interference in a multi-carrier communications system are provided. A first signal is received by a receiver. The first signal comprises a source signal transmitted on a carrier over a communications channel. The first signal reflects a source symbol mapped to one of a plurality of signal constellation points, and each signal constellation point is associated with a different one of a plurality of signal clusters. A received representation of the source signal with respect to the source symbol is acquired from the first signal. A plurality of likelihood metrics are determined, where each likelihood metric is based on the received representation of the source signal with respect to the source symbol and a different one of a plurality of core parameters, wherein each core parameter is based on a centroid estimate with respect to a different one of the signal clusters.

Abstract: A receiver including: a memory, and a processor configured to calculate a plurality of soft decision values based on a received symbol to which a plurality of bits are mapped, to select at least one first soft decision value of the plurality of soft decision values, to calculate at least one relative value of at least one second soft decision value of the plurality of soft decision values other than the at least one first soft decision value, based on the at least one first soft decision value, to store the at least one first soft decision value and the at least one relative value, in the memory, and to estimate the plurality of bits based on the at least one first soft decision value and the at least one relative value which are stored in the memory.

Abstract: A method for detecting communications from multiple transmission antennas includes receiving a signal with at least one receive antenna, wherein the signal comprises data transmitted from at least one of the transmission antennas, calculating an equalized received signal and an equalized channel matrix using the signal and a channel matrix, determining whether a correlation factor threshold value is exceeded, and based on the act of determining, generating a listed based log likelihood ratio (LLR) soft output or a MMSE LLR soft output based on the equalized received signal and the equalized channel matrix.

Abstract: Systems and methods are provided for determining a data value for a bit of interest in a received data signal. A closest 0-bit symbol candidate is selected from a plurality of 0-bit symbol candidates using a symbol selection distance approximation. A closest 1-bit symbol candidate is selected from a plurality of 1-bit symbol candidates using the symbol selection distance approximation. A 0-bit distance between the received data signal and the selected 0-bit symbol candidate is determined, and a 1-bit distance between the received data signal and the selected 1-bit symbol candidate is determined. A log likelihood ratio is calculated for the bit of interest using the determined 0-bit distance and the determined 1-bit distance.

Abstract: A method of determining a transmitted vector (x) in a MIMO receiver includes the steps of receiving a received vector (y) representative of the transmitted vector (x), generating a first random number and forming, in a first iteration, a first symbol of a first candidate vector, the candidate vector representing a potential solution vector. The step of forming is based on a first approach if the first random number is greater than a first predetermined value (q), but is based on a second approach if the random number is less than or equal to the first predetermined value (q). The first approach randomly selects the first symbol from a uniform distribution of symbols in the transmission alphabet. The second approach selects the first symbol based on Gibbs sampling. The method represents a randomized Markov Chain Monte Carlo (RMCMC) sampling technique.

Abstract: A system includes a channel estimator configured to receive a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols via a plurality of respective antennas, and generate estimates of a channel based on the plurality of OFDM symbols. A demodulator is configured to generate a plurality of demodulated symbols based on the plurality of OFDM symbols and the estimates of the channel. A decoder is configured to receive the estimates of the channel from the channel estimator, receive the plurality of demodulated symbols from the demodulator, and calculate decision metrics for the plurality of OFDM symbols using both the estimates of the channel and the plurality of demodulated symbols.

Abstract: A log likelihood ratio arithmetic circuit for calculating a log likelihood ratio from information of a coordinate of a reception signal point to be applied to a communication system using a quadrature amplitude modulation method, wherein the circuit limits a scope within which a value of the log likelihood ratio varies corresponding to a position of the reception signal point to a range between adjacent signal points including a hard-decision threshold of a bit, and wherein the value of the log likelihood ratio does not vary outside of the range between the adjacent signal points.

Abstract: One aspect of the present invention concerns the management of processing resource allocations for a Turbo receiver, where such resources are consumed from a finite resource budget within a defined processing time interval. The contemplated Turbo receiver attempts to allocate more processing resources to those demodulation and/or Turbo decoding tasks that make more valuable contributions with respect to the ultimate goal of successfully decoding all data streams that are of interest in a received signal. The advantageous management approach allows the Turbo receiver to obtain better results for a given consumption of processing resources, and further permits the Turbo receiver to quit upon either achieving a successful outcome within a defined processing time interval or exhausting the budgeted resources.

Abstract: An approach for Soft-output K-Best MIMO detection comprises computing an estimated symbol vector and Log-Likelihood Ratio (LLR) values for transmitted bits. The approach includes a relevant discarded paths selection process, a last-stage on-demand expansion process, and a relaxed LLR computation process. The relevant discarded paths selection process includes analyzing the K-Best paths and discarded paths at each intermediate tree level and selecting only those discarded paths for further processing that will help in LLR computation for at least one of the transmitted bits. The last-stage on-demand expansion process includes expanding K paths at the tree level 2NT?1 (NT=number of transmit antennas) on-demand to only 2K?1 lowest Partial Euclidean Distance (PED) paths at last tree level 2NT. The relaxed LLR computation scheme includes approximating LLR computations by assuming that discarded path PED is greater than or equal K-Best path PED.

Abstract: Systems and methods are provided for decoding signal vectors in multiple-input multiple-output (MIMO) systems, where the receiver has received one or more signal vectors from the same transmitted vector. The receiver combines the received vectors by vector concatenation The concatenated vector may then be decoded using, for example, maximum-likelihood decoding. In some embodiments, the combined signal vector is equalized before decoding.

Abstract: A noise thresholder of a baseband modem integrated circuit (BMIC) compares measured noise variances on corresponding receiver paths to a pre-established threshold minimum value. The noise thresholder assigns as a noise variance value for a corresponding receiver path either (a) a measured noise variance value for each receiver path having a measured noise variance that is larger than the pre-established threshold minimum, and (b) the pre-established threshold minimum value for each receiver path having a measured noise variance that is less than or equal to the pre-established threshold minimum value. A noise balancer performs noise balancing to provide a same signal to noise ratio (SNR) across all receiver paths, based on the assigned noise variances provided at the noise thresholder. A detection engine utilizes a lowest assigned noise variance value and outputs yielded by the noise balancer to simplify equalization computations while providing a high performance symbol detection capability.

Abstract: Methods and apparatus are provided for direct synthesis of RF signals using maximum likelihood sequence estimation. An RF digital RF input signal is synthesized by performing maximum likelihood sequence estimation on the digital RF input signal to produce a digital stream, such that after filtering by a prototype filter the produced digital stream produces a substantially minimum error. The substantially minimum error comprises a difference between a digital output of the prototype filter and the digital RF input signal. The digital stream is substantially equal to the input digital RF signal. The digital stream can be applied to an analog restitution filter, and the output of the analog restitution filter comprises an analog RF signal that approximates the digital RF input signal.

Abstract: A configurable decoder within a receiver (for example, within a wireless communication device) includes numerous decoders. In one mode, the multiple decoders are used to decode different sub-packets of a packet. When one decoder completes decoding the last sub-packet assigned to it of the packet, then that decoder generates a packet done indication. A control circuit receives the packet done indications, and when all the decoders have generated packet done indications then the control circuit initiates an action. In one example, the action is the interrupting of a processor. The processor responds by reading status information from the control circuit, thereby resetting the interrupt. End-of-packet markers are usable to generate packet done indications and to generate EOP interrupts. Similarly, end-of-group markers are usable to generate group done indications and to generate EOG interrupts. The decoder block is configurable to process sub-packets of a packet using either one or multiple decoders.

Abstract: A method of operation of a communication system includes: calculating a shift distance of a received signal having a distortion; calculating an approximate likelihood of the received signal matching a transmitted signal from the shift distance; determining a bias factor from the distortion; and selecting a determined modulation maximizing a combination of the approximate likelihood and the bias factor for communicating with a device.

Abstract: In a method for generating a physical layer (PHY) data unit for transmission via a communication channel, first data and second data that correspond to a unit of audio, video, and/or image information is received. The first data and the second data are encoded and modulated so that a resulting data rate of the first data is less than a resulting data rate of the second data. The first data and the second data are parsed to a plurality of spatial streams, and a single PHY data unit that includes the plurality of spatial streams is generated.

Abstract: A receiver for receiving data carried by multiple carriers, the receiver having: estimation means for forming an estimate of the reliability with which data from one or more of the carriers is received as distinct from the reliability with which data from one or more other of the carriers is received; and a decoder arranged for forming an estimate of the symbols represented by the data received from the carriers in dependence on the estimate of reliability.

Abstract: A receiver may be operable to receive an inter-symbol correlated (ISC) signal, and generate a plurality of soft decisions as to information carried in the ISC signal. The soft decisions may be generated using a reduced-state sequence estimation (RSSE) process. The RSSE process may be such that the number of symbol survivors retained after each iteration of the RSSE process is less than the maximum likelihood state space. The plurality of soft decisions may comprise a plurality of log likelihood ratios (LLRs). Each of the plurality of LLRs may correspond to a respective one of a plurality of subwords of a forward error correction (FEC) codeword.

Abstract: The invention relates to a detection method using a receiver of a digital communication system for the detection of a symbol from a received signal, which signal is transmitted by a transmitter of the digital communication system, wherein the symbol is a selected symbol out of a predetermined set of symbols and wherein each symbol of the predetermined set comprises a sequence of chips wherein each of the chips is PSK-modulated according to a selected modulation code.

Abstract: An orthotope sphere decoding method of a multiple antenna system is disclosed. The method includes performing tree search using a depth-first method by performing an OC-test on the nodes on which the tree search of orthotope sphere decoding will be performed and performing an SC-test on nodes passing the OC-test; and selecting a transmission symbol having a smallest PED value as a final signal as a result of the search.

Abstract: The present disclosure provides an orthotope sphere decoding method of a multiple antenna system. The method includes: tree mapping a node having highest pruning potential that can be predicted at a root of a tree of orthotope sphere decoding to a root level of the tree, among nodes to be mapped to the tree; and performing tree search of the orthotope sphere decoding on the nodes mapped to the tree.

Abstract: A radio communication apparatus includes a radio frequency unit that receives signals transmitted from a transmitter, and a baseband processor that obtains channel estimates based on the received signals and performs signal detection based on the channel estimates according to a QRM-MLD method. The baseband processor includes a stream separator that, in a first stage, detects a region to which a signal belongs, selects symbol candidates based on the detected region, and calculates metrics for the selected symbol candidates. In a second stage, the stream separator selects symbol candidates based on the metrics calculated for the symbol candidates selected in the first stage. After starting calculation of the metrics for the symbol candidates selected in a previous stage, the stream separator selects symbol candidates of a next stage based on metrics of surviving paths to which the symbol candidates whose metrics have been calculated belong.

Abstract: In one embodiment of a communications network, the predetermined encoding scheme and symbol constellation configurations are chosen so that the range in channel qualities that the encoding scheme and symbol constellation configurations are designed to be utilized within overlap with each other. This overlapping provides hysteresis, which reduces the frequency with which a subscriber must alter encoding scheme and symbol constellations. Reducing the frequency of changing encoding scheme and/or symbol constellation eliminates the communication overhead associated with these changes and increases throughput by enabling the subscriber to spend more time transmitting data.

Abstract: To demodulate a quadrature amplitude modulation (QAM) signal, a reception point is determined corresponding to a symbol in the QAM signal that is received where the symbol is mapped to one reference point of a plurality of reference points in a rotated constellation and the plurality of reference points are represented by an in-phase (I) coordinate and a quadrature-phase (Q) coordinate. A plurality of candidate points corresponding to a portion of the plurality of reference points are selected based on distances between the reception point and the respective reference points. The reception point is demapped by calculating a plurality of log-likelihood ratios based on the plurality of candidate points, the plurality of log-likelihood ratios corresponding to bits of data represented by the reception point.

Abstract: Disclosed herein are methods of processing transmissions in a wireless communication system to detect whether a transmission unit contains transmitted data, systems for processing transmissions in a digital communications system to detect the same, receivers for processing transmissions in a wireless communications system and computer readable media implementing a method for processing the same. In one embodiment, a method of processing transmissions in a wireless communication system to detect whether a transmission unit contains transmitted data includes: generating an averaged function of bit reliability indicators from a plurality of received samples and applying a test to compare an average of ln cosh(·) (natural logarithm of the hyperbolic cosine) values for the reliability indicators, with a factor proportional to an average signal-to-disturbance ratio of the plurality of samples to determine if the transmission unit contains transmitted data.

Abstract: A receiver in a multiple-input multiple-output (MIMO) system is provided. The receiver includes a channel estimator estimating a channel based on a receiving signal, a minimum mean square error (MMSE) based reciprocal log likelihood ratio (R-LLR) calculator connected with the channel estimator and calculating an R-LLR based on the receiving signal and the estimated channel, and a channel decoder connected with the MMSE based R-LLR calculator and decoding the channel and the receiving signal based on the calculated R-LLR, wherein the R-LLR is calculated based on the reciprocity.

Abstract: Systems and/or methods for communications wherein a plurality of spatial streams are received. Each of these spatial streams comprises a symbol having at least one phase shifted pilot signal. The Minimum Mean Square Error (MMSE) estimates of the phase shifted pilot signals are computed and the MMSE estimates are used to estimate phase errors for the symbols.

Abstract: A computer estimates multiple angles of arrival of a target signal received by an array of commutated antenna elements. In one aspect, samples of a received target signal obtained from an array of communicated antenna elements and from an element in an array of reference antenna elements are processed to make maximum-likelihood-estimations of multiple angles of arrival at which signals are received by the array of commutated antenna elements; and a display is mapped over time and frequency of the estimations, with the angle of arrival for a particular sample being represented by a variable given display feature.

Abstract: A technique includes performing non-joint demodulation of a desired signal in response to a carrier-to-interference ratio estimate for a received signal being greater than or equal to a threshold level, the non-joint demodulating being based on first channel impulse response coefficients associated with the desired signal and second channel impulse response coefficients associated with one or more interfering signals. The technique includes determining the second channel impulse response coefficients based on a first cross-correlation function between the received signal and a training sequence of an interfering signal of the one or more interfering signals, determining the first channel impulse response coefficients based on a second cross-correlation function between the received signal and a training sequence of the interfering signal, and determining a time difference between a time value of a peak in the first cross-correlation function and a time value of a peak in the second cross-correlation function.

Abstract: A method for operating a Viterbi decoder uses few data move operations to improve efficiency. The Viterbi decoder predicts a state in which the convolution encoder might have operated while generating a convolutionally encoded data stream. The Viterbi decoder maintains a first set of states and based on the received convolutionally encoded data stream, predicts second and third sets of states. The Viterbi decoder then calculates first and second sets of decision bits based on the transitions to the second and third sets of states. Path metric values associated with the third set of states are stored in a memory buffer. Thereafter, during trace-back, the Viterbi decoder extracts first and second decoded bits from first and second sets of decision bits respectively.

Abstract: Systems and methods for reconstructing digital information in a multiple-input receiver from signals transmitted by a multiple-output transmitter, in a multiple-input multiple-output (MIMO) communications channel are provided. A plurality of signal streams are obtained from a plurality of transmitted signals and a first candidate signal value is selected for each of the plurality of signal streams. A plurality of additional candidate signal values are also selected for each of the plurality of signal streams in response to selecting the first candidate signal value. A log-likelihood ratio (LLR) is computed from the plurality of signal streams based on all of the selected candidate signal values. Digital information may then be estimated based on the computed LLR.

Abstract: A receiver system and method for recovering information from a symbol data sequence Y. The symbol data sequence Y corresponds to a symbol data sequence X that is transmitted onto the channel by a transmitter. The symbol data sequence X is generated by the transmitter based on associated information bits. At the receiver, a set of two or more processors operate in parallel on two or more overlapping subsequences of the symbol data sequence Y, where each of the two or more overlapping subsequences of the symbol data sequence Y corresponds to a respective portion of a trellis. The trellis describes redundancy in the symbol data sequence Y. The action of operating in parallel generates soft estimates for the associated information bits. The soft estimates are useable to form a receive message corresponding to the associated information bits.

Abstract: In one embodiment, a method can provide for dynamic updating of slope values used in determining a soft decision for a demodulated signal obtained in a receiver from a broadcast signal received by the receiver. The method includes generating a channel estimate for a channel traversed by the signal, computing channel state information from the channel estimate, computing statistical information from the channel state information, determining a slope value based at least in part on the statistical information, calculating a log-likelihood ratio (LLR) value for the signal, and applying the slope value to the LLR value to obtain a weighted LLR value.

Abstract: Soft bit metric generation computational complexity can be reduced by identifying and utilizing only the dominant terms in a reliability calculation such as a logarithmic likelihood ratio (LLR). The dominant terms are those terms for which the signs of the x and y components match those of channel outputs of the channel outputs. One technique for identifying the dominant terms is by determining the most likely transitions from two consecutive channel output samples Values for the dominant terms can be estimated by either the joint reliability of two consecutive samples of the in-phase component (x1,x2) or by the joint reliability of two consecutive samples of the quadrature components (y1,y2).

Abstract: A circuit is provided comprising detector circuitry, calculating circuitry, and determining circuitry. The detector circuitry is figured to generate an I data signal magnitude value of a sampled I data signal and a Q data signal magnitude value of a sampled Q data signal. The calculating circuitry is configured to calculate a phase shift angle ?I between first and second equal and constant or substantially equal and constant envelope constituents of the sampled I data signal and to calculate a phase shift angle ?Q between first and second substantially equal and substantially constant envelope constituents of the sampled Q data signal. The determining circuitry is configured to determine in-phase and quadrature amplitude information of the substantially equal and substantially constant envelope constituents of the sampled I signal and to determine in-phase and quadrature amplitude information of the first and second substantially equal and substantially constant envelope constituents of the sampled Q signal.

Abstract: In a method of demodulating a signal transmitted via a multiple input multiple output (MIMO) communication channel, a data symbol vector is received, the data symbol vector including a plurality of data symbols that are received via a plurality of antennas. The received data symbol vector corresponds to a transmitted data symbol vector including a plurality of transmitted data symbols. A plurality of candidate vectors are generated for the transmitted data symbol vector, the plurality of candidate vectors being less than all possible vectors for the transmitted data symbol vector. One candidate vector is selected from the plurality of candidate vectors such that the one candidate vector minimizes a distance value corresponding to a Euclidean distance between the received data symbol vector and a channel estimate matrix multiplied with the candidate vector.

Abstract: A parallel implementation of the Viterbi decoder becomes more efficient when it employs end-state information passing as disclosed herein. The improved efficiency enables the usage of less area and/or provides the capacity to handle higher data rates within a given heat budget. In at least some embodiments, a decoder chip employs multiple decoders that operate in parallel on a stream of overlapping data blocks, using add-compare-select operations, to obtain a sequence of state metrics representing a most likely path to each state. Each decoder passes information indicative of a selected end-state for a decoder operating on a preceding data block. Each decoder in turn receives, from a decoder operating on a subsequent data block, the information indicative of the selected end-state. The end-state information eliminates any need for post-data processing, thereby abbreviating the decoding process.

Abstract: Embodiments of a space-time decoder and methods for decoding Alamouti-encoded signals in high-Doppler environments are generally described herein. Other embodiments may be described and claimed. In some embodiments, soft-symbol outputs are generated from received symbols, a channel rate-of-change, and channel coefficients. Maximum-likelihood decoding may be performed to generate hard-symbol outputs from the soft-symbol outputs.

Abstract: A digital video recorder stores digital video streams having sequences of encoded frames that are predominantly non-keyframes. The digital video recorder synthesizes keyframes for the digital video stream by decoding the frames in sequence and occasionally capturing the state of the decoder as it decodes the frames. The decoder states are stored in a state index in association with the frames. During playback at normal or accelerated speeds, the digital video recorder is capable of random accelerated access of any frame in the digital video stream. A decoder state associated with the accessed frame is retrieved from the state index and used to begin decoding at or near the accessed frame. The decoder state initializes a playback decoder to the state that enables complete decoding and rendering of the accessed frame without having to decode multiple frames previous to the accessed frame, thereby minimizing time delays in playback.

Abstract: A receiver of a multiple-input multiple-output (MIMO) system performs QR decomposition of the channel matrix to enable detection of a transmitted vector in a layered manner. In each layer, a sub-vector of the transmitted vector is estimated. A reactive tabu search is performed if an estimated symbol differs from a nearest symbol in the alphabet by a predetermined value. The receiver may order the entries of the channel matrix prior to QR decomposition to enable estimation in an optimum order. In another embodiment, a receiver performs multiple reactive tabu searches to estimate a transmitted vector. The receiver employs a fixed threshold or a variable threshold for a cost function used in the multiple reactive tabu searches depending on whether the MIMO system is under-determined or not. The techniques enable low bit-error rate (BER) performance in MIMO systems with large number of antennas and when higher-order modulation techniques are used.