Abstract: Systems and methods are provided for generating error events for decoded bits using a Soft output Viterbi algorithm (SOYA). A winning path through a trellis can be determined and decoded information can be generated. Path metric differences can be computed within the trellis based on the winning path. A plurality of error event masks and error event metrics can be generated based on the decoded information and the path metric differences.

Abstract: A decision feedback equalizer is operated by making first symbol decisions from an output of the decision feedback equalizer such that the first symbol decisions are characterized by a relatively long processing delay, by making second symbol decisions from the output of the decision feedback equalizer such that the second symbol decisions are characterized by a relatively short processing delay, and by determining tap weights for the decision feedback equalizer based on the first and second symbol decisions. The first symbol decisions may be derived from the output of a long traceback trellis decoder. The second symbol decisions may be derived either from the output of a short traceback trellis decoder or from shorter delay outputs of the long traceback trellis decoder.

Abstract: Different sets symbols are precluded at prescribed times in time-dependent trellis coding. This increases the distances between different individual symbols as well as the distances between trellis codes, which increases the robustness of data transmission. The symbols that are precluded in this time-dependent trellis coding are determined in advance according to a prescribed pattern, which pattern does not depend on the history of previous symbols. The Viterbi decoder used for trellis decoding in a receiver can be designed to take advantage of knowledge concerning which different sets of symbols are precluded at prescribed times.

Abstract: A digital broadcast transmitting system and a signal processing method thereof that improves the receiving performance of the system. A digital broadcast transmitter includes a randomizer to receive and randomize a transport stream into a specified position of which stuff bytes are inserted, a replacement sequence generator to generate known data including a predefined sequence, a stuff-byte exchange unit to insert the known data into the specified position of the transport stream into which stuff bytes are inserted, an encoder to encode the transport stream output from the stuff-byte exchange unit for an error correction, and a transmission unit to modulate the encoded transport stream, RF-convert the modulated transport stream and transmit the RF-converted data. The digital broadcast receiving performance is improved even in an inferior multi-path channel by detecting the known data from the received transmission and using the known data for synchronization and equalization.

Abstract: A method for receiving spread spectrum signals and for initial code acquisition from the received signals comprises de-spreading the received signals, based on code phase synchronization, to produce a de-spread signal; and performing a modulation detection based on a change of time-domain characteristic of the de-spread signal.

Abstract: An information source encoding method for encoding a Gaussian integer signal includes the steps of: inputting a signal value sequence of a Gaussian integer signal as an encoding target; transforming signal values included in the input signal value sequence into integer pairs, each having two integers, arranged in the input order; regarding each of the integer pairs as a lattice point on two-dimensional coordinates, and obtaining integer values greater than or equal to zero by performing a two-dimensional-to-one-dimensional mapping in which the shorter the distance from each lattice point to the origin, the smaller the value assigned to the lattice point by the mapping; and encoding the integer values using codes which are used for encoding an information source that follows an exponential distribution.

Abstract: A system and method for non-uniform bit allocation in the quantization of channel state vectors is provided. A method for communications node operation includes receiving a bit-allocation profile for use in quantizing channel state information, measuring a communications channel between the communications node and a controller, generating channel state information based on the measurement, computing a bit representation of the channel state information, transmitting the bit representation to the controller, and receiving a transmission from the controller. The computing makes use of quasi-tail-biting trellis decoding, and the computing is based on the bit-allocation policy. The transmission makes use of the channel state information transmitted by the communications node.

Abstract: A Viterbi pack instruction is disclosed that masks the contents of a first predicate register with a first masking value and masks the contents of a second predicate register with a second masking value. The resulting masked data is written to a destination register. The Viterbi pack instruction may be implemented in hardware, firmware, software, or any combination thereof.

Abstract: A multi-channel sequential Viterbi decoder includes: an input data buffer, a “Read Single Data Word from Input Data Buffer” signal driver, a processing unit selector, a decoder channel parameters registers unit, a processing unit for the “Reset Path Metrics” command, a processing unit for the “Set Path Metric Value for the Given Path Number” command, a processing unit for the “Get Single Bit from the Path with Given Number” command, a processing unit for the “Process Input Samples” command, a decoding paths and path metrics RAM, a unit for generating current decoder channel base address for the decoding paths and path metrics RAM, a unit for generating cell address for the decoding path and path metric RAM, and a data buffers unit for decoder channels output.

Abstract: Method and apparatus for decoding code words received over a communication channel are disclosed. A radius-adaptive sphere decoding methodology reduces the number of operations in sphere-constrained search. Imposing probabilistic noise constraint on top of sphere constraint, particularly at an early stage, provides a more stringent necessary condition. Hence, many branches that are unlikely to be selected are removed in the early stage of sphere search. The trade-off between computational complexity and performance can be controlled by adjusting the pruning probability.

Abstract: A wireless communication receiver includes a first signal processing block, a second signal processing block, and a de-interleaver. The first signal processing block is configured for receiving a wireless communication signal and processing the wireless communication signal to generate a first output. The de-interleaver is coupled between the first signal processing block and the second signal processing block, and includes a plurality of branches implemented for de-interleaving the first output to generate a second output. The de-interleaver starts outputting the second output to the second signal processing block for further signal processing before all buffers included in the branches are full, and informs the second signal processing block of data derived from one or more unfull buffers included in the branches.

Abstract: A method of demodulating a signal on which is modulated, using a quadrature amplitude modulation scheme, a plurality of information symbols, the method including: determining at least one QAM detection threshold corresponding to one or more of said information symbols; and demodulating each information symbol on the basis of at least one respective QAM detection threshold.

Abstract: The outer convolutional coding of the signals used to transmit mobile-handheld (M/H) service data within digital-television (DTV) signals is subjected to anti-Gray coding, either before or after its interleaving, but before its inner convolutional coding. In a receiver for such M/H-service data, portions of the trellis decoded DTV signal containing soft decisions concerning symbol-interleaved convolutionally coded M/H-service data are recoded for a Gray-code mapping of symbols to modulation levels. This is done either before or after symbol de-interleaving, but before decoding the outer convolutional coding. Soft decisions concerning extrinsic information to be fed back to the ? trellis decoder to close a turbo decoding loop are derived from soft decisions as to the M/H-service data, which derivation includes re-coding for a binary-code mapping of symbols to modulation levels. Each re-coding procedure can be performed using ROM, but preferably is performed using simple digital logic.

Abstract: A receiver for receiving a sequence of OFDM symbols transmitted via a channel. Each OFDM symbol comprises a plurality of data bearing sub-carriers and a plurality of pilot bearing sub-carriers. The receiver includes a channel estimator, and the channel estimator includes a pilot data extractor, a pilot data extrapolator and a pilot data interpolator operable to process the pilot data by interpolating between the extrapolated pilot data in time and frequency. The receiver also comprises a discontinuity detector for detecting a discontinuity in the pilot data processed by the channel estimator, and a controller, which upon detection of a pilot data discontinuity by the discontinuity detector, is operable to provide a control signal to the channel estimator which causes at least one of the pilot data extractor, the pilot data extrapolator and the pilot data interpolator to compensate for the discontinuity in the pilot data.

Abstract: One embodiment comprises a transmitter precoder operating on an input signal to produce an output signal for modulation. The output signal is transmitted using a constellation with a constellation density. The transmitter precoder comprises scaler logic, precoder logic and selection logic. The scaler logic scales the input signal to maintain constant power on the input signal independent of the constellation density. The precoder logic precodes the scaled signal to produce a dither signal limited to a range of values. The range is inversely proportional to the constellation density. The selection logic is operable in two states. In the first state, the selection logic combines the scaled signal with the dither signal to produce the output signal. In the second state, the selection provides the scaled signal as the output signal.

Abstract: Compact pulse shape partial response (CPS PR) signaling is developed for trellis based signals like QM-MSK, and for PAM/QAM type signals to improve the performance to bandwidth tradeoff. Compact pulse shaped signals are partial response signals that employ a very short pulse shaping filter and use Viterbi decoding to optimally detect the CPS signal in presence of its inherent inter-symbol interference. The CPS filters considered herein have much shorter impulse response than the well-known raised cosine (RC) filter. There is no need to equalize the received signal to eliminate ISI or to allow a fixed amount of ISI between received signal samples as sampled at the symbol rate as is common in partial response maximum likelihood (PRML) systems. Numerical results indicate that CPS QM-MSK and CPS QAM provides between several dB of gain, depending on constellation size, over PR-CPM and RC QAM, when compared at a given value of bandwidth, i.e., B99Tb.

Abstract: A baseband processing module of a wireless terminal includes a Turbo decoding module. The Turbo decoding module decodes a Turbo code word to produce one or more Media Access Control (MAC) packet(s) carried by the turbo decode word. Each MAC packet includes a MAC packet header and the MAC packet payload, which carries one or more Radio Link Control (RLC) Packet Data Units (PDUs). The Turbo decoding module decodes the MAC packet header to determine boundaries of the PDUs carried in the MAC packet payload. The Turbo decoding module decodes RLC PDU headers and RLC PDU payloads of the RLC PDUs. The Turbo decoding module writes the decoded MAC packet header, the decoded RLC PDU headers, and the decoded RLC PDU payloads to memory in a word-aligned format. The Turbo decoding module may also operate in various other Turbo decoding modes.

Abstract: There is provided a system and method of operating a multiple-input multiple-output (MIMO) receiver with N antennas in a wireless communication system. The method includes measuring N vectors, each vector defining channel transfer coefficients between M antennas of a transmitter and a corresponding antenna of the receiver. Additionally, a vector in a linear space generated by the N measured vectors is selected and quantized values of less than M components of the selected vector are fed back to the transmitter.

Abstract: A method for communication includes receiving a communication signal conveying multiple encoded bits of an Error Correction Code (ECC). Respective N-bit soft decoding metrics are computed with respect to the bits of the ECC. A scaling factor is computed based on at least one characteristic of the N-bit soft decoding metrics and on at least one property of the received communication signal. The N-bit soft decoding metrics are scaled by the scaling factor. The scaled N-bit soft decoding metrics are quantized to produce respective K-bit metrics, K<N. The ECC is decoded using the scaled and quantized soft decoding metrics.

Abstract: A transmitter according to the present invention includes a mapping unit configured to convert transmitted data into data pieces associated with individual subcarriers, an inverse Fourier transform unit configured to convert the data pieces into a time-series signal, and a symbol generation unit configured to generate symbols for radio transmission from the time-series signal. The mapping unit associates the transmitted data with subcarriers different from predefined multiple subcarriers arranged at even intervals on a frequency axis. A demapping unit of a receiver according to the present invention supplies data comprising the data pieces associated with the subcarriers different from the predefined multiple subcarriers arranged at even intervals on a frequency axis as the data for restoration.

Abstract: Certain embodiments provide methods and apparatus for decoding a string of data bits, encoded with a turbo encoding scheme, in a wireless communication system. One or more a-priori bit values corresponding to expected bit values at one or more identified bit locations in the string of data bits may be identified. One or more branch metrics used in a turbo decoding scheme may be manipulated to effectively remove decoding paths, from a collection of possible decoding paths, based at least on the identified one or more a-priori bit values, resulting in one or more remaining decoding paths. The string of data bits may be decoded by selecting a decoding path from the one or more remaining decoding paths.

Abstract: A method and apparatus for decoding encoded data bits of a wireless communication transmission are provided. A set of a-priori bit values corresponding to known bit values of the encoded data bits may be generated. Decoding paths that correspond to decoded data bits that are inconsistent with the a-priori bit values may be removed from the possible decoding paths to consider, and decoding the encoded data bits by selecting a decoding path from remaining decoding paths of the possible decoding paths that were not removed.

Abstract: A digital television (DTV) transmitter and a method of processing known data in the DTV transmitter are disclosed. The method of processing known data in a digital television (DTV) transmitter includes generating a known data sequence, trellis-encoding the known data sequence, the trellis-encoded known data sequence having upper, middle, and lower bits, wherein at least one of the upper, middle, and lower bits has an m-sequence property, and mapping the trellis-encoded known data sequence into one of 2-level, 4-level, and 8-level data sequences, wherein the mapped data sequence has substantially an m-sequence property, wherein a data sequence has an m-sequence property when a peak value among auto-correlation values of the data sequence having a length of N is 1 and all the off-peak auto-correlation values are ?1/N.

Abstract: A method of Dirty Paper Coding DPC using nested lattices is disclosed. The complexity of DPC can be reduced by scaling nested lattices and mapping interference to a lattice point of the scaled lattice.

Abstract: A decoding circuit performs, with a single circuit, decoding in association with various image encoding systems. A pattern storing unit stores scan pattern data for a scan pattern, a control unit writes scan pattern data for supplied encoded data in the pattern storing unit, a pattern readout control unit reads out the scan pattern data stored in the pattern storing unit, a variable length decoding unit restores coefficient data from the supplied encoded data, and an inverse scan processing unit rearranges the restored coefficient data according to the scan pattern data read out from the pattern storing unit.

Abstract: A digital television transmitter and a method of coding main and enhanced data in the digital television transmitter are disclosed. In the digital television transmitter, a byte-symbol converter converts main and enhanced data packets into symbols, wherein at least one of the enhanced data packets may include data place holders for known data symbols. A known data generator generates a known data symbol. A symbol processor processes a first symbol outputted from the byte-symbol converter. Herein, the symbol processor may post-decode a first bit of the known data symbol and output the post-decoded bit and an initialization data bit when the first symbol is a symbol representing one of the place holders. A trellis encoder has one or more memories for trellis-encoding a second symbol outputted from the symbol processor, wherein the memories are initialized when the initialization data bit is processed in the trellis encoder.

Abstract: A digital television (DTV) transmitter and a method of processing data in the DTV transmitter are disclosed. A pre-processor pre-processes the enhanced data by coding the enhanced data for forward error correction (FEC) and expanding the FEC-coded enhanced data. A data formatter generates enhanced data packets including the pre-processed enhanced data and for inserting known data to at least one of the enhanced data packets. A first multiplexer multiplexes the enhanced data packets with main data packets including the main data. An RS encoder RS-codes the multiplexed main and enhanced data packets, the RS encoder adding systematic parity data to each main data packet and adding RS parity place holders to each enhanced data packet. And, a data interleaver interleaves the RS-coded main and enhanced data packets, wherein a known data sequence is included in every Nth enhanced data segment outputted from the data interleaver.

Abstract: A new protocol is proposed for transmission of data through lines such as telephone lines. The tones of a signal are grouped, and Trellis encoding is performed only of the members of a group. The computational cost of coding and decoding the data is reduced (compared to treating all the tones of a given direction equivalently), and the invention makes it possible to significantly reduce the computational and memory requirements of the encoder and decoder. Furthermore, Trellis decoding errors are not propagated between the groups.

Abstract: An apparatus for generating a precoding matrix codebook includes a matrix group generator to generate a first group of unitary matrices based on a vector-based codebook for precoding of a multiple input multiple output (MIMO) communication scheme; a matrix group extender to extend the first group of unitary matrices to generate a second group of unitary matrices; and a matrix group selector to select a group of columns corresponding to a communication rank from each of the unitary matrices that are elements of the second group so that the columns are optimized based on a distance between the columns corresponding to the communication rank.

Abstract: A spatial spreading unit is configured to utilize a spatial spreading matrix to distribute two or more encoded spatial data streams to transmission antennas. The spatial spreading matrix has components (i) associated with each row of a row dimension having a number of rows equal to the number of the transmission antennas to be used to transmit the encoded spatial data streams and (ii) associated with each column of a column dimension having a number of columns equal to the number of the encoded spatial data streams to be transmitted.

Abstract: A code encoding apparatus includes a delay circuit and a code generator. The delay circuit generates delayed information based on p-bit input information received in parallel. The delayed information is generated according to a clock. The code generator generates n·p-bit code based on at least one of the input information and the delayed information, where n is a rational number.

Abstract: In a pulse-based communication system a transmitting device may generate a series of pulses to convey information via a communication medium to a receiving device. In some situations, interference from one or more interfering devices may alter the pulse energy as it is transmitted through the communication medium. To mitigate the effect of such interference, a receiving device may mark certain received pulses as erasures. In this way, such pulses may be ignored during the decoding operation of the receiver.

Abstract: A feedforward receiver and method are described herein that address inter-symbol interference in received symbols by using an enhanced equalizer to generate joint soft values (joint information of a previous modem bit x? and a modem bit x) and an enhanced decoder which uses the joint soft values and side information (bias about the previous modem bit x?) to output a more reliable information bit x.

Abstract: An FFT processor for an OFDM receiver includes multiple interrelated operational blocks. The FFT processor is configured to perform data demodulation, channel estimation, and fine timing acquisition on received OFDM symbols. The FFT processor incorporates a pipelined FFT engine using a memory architecture shared with channel estimation and demodulation blocks. The combination of the shared memory structure and the pipelined FFT operation enable the channel estimation and demodulation processing to be completed during the time used to capture the next received symbol.

Abstract: The present invention maps coded bits that have been output from a low density parity check coder 11 onto specific bit positions on a 16 QAM constellation diagram in accordance with a column weighting of the coded bits.

Abstract: A method for detection of a control channel includes receiving data transmitted via the control channel. A control channel receive quality is estimated based on a metric difference between a metric of a known final trellis state and a minimum metric amongst the metrics of the trellis states based on the received data. It is decided whether or not to detect the control channel depending on the estimated control channel receive quality.

Abstract: A decoder for a layered modulation system can be configured to independently and concurrently decode each of a base and enhancement layer. The base layer decoder and enhancement layer decoder can be configured substantially in parallel and can each operate concurrently on the same received layered modulation symbol. Each of the base and enhancement layer decoders can be configured with a bit metric module that is configured to determine a signal quality metric based on the received symbol. In systems having turbo encoded data, the bit metric module can be configured to determine a log likelihood ratio. The ratio is based in part on a channel estimate and an energy ratio used in the layered modulation constellation.

Abstract: Compact pulse shape partial response (CPS PR) signaling is developed for trellis based signals like QM-MSK, and for PAM/QAM type signals to improve the performance to bandwidth tradeoff. Compact pulse shaped signals are partial response signals that employ a very short pulse shaping filter and use Viterbi decoding to optimally detect the CPS signal in presence of its inherent inter-symbol interference. The CPS filters considered herein have much shorter impulse response than the well-known raised cosine (RC) filter. There is no need to equalize the received signal to eliminate ISI or to allow a fixed amount of ISI between received signal samples as sampled at the symbol rate as is common in partial response maximum likelihood (PRML) systems. Numerical results indicate that CPS QM-MSK and CPS QAM provides between several dB of gain, depending on constellation size, over PR-CPM and RC QAM, when compared at a given value of bandwidth, i.e., B99Tb.

Abstract: A method for data transmission in a multiple input multiple output (MIMO) system. The method for data transmission includes receiving multiple input data streams and performing low density parity check (LDPC) encoding of the input data streams utilizing a parity check matrix. The parity check matrix comprises a plurality of sub-parity check matrices for encoding respective associated ones of the input data streams and performing space time encoding for transmitting the LDPC encoded input data streams over a plurality of antennas. The performing of the LDPC encoding of the input data streams includes generating one or more connection matrices, each connection matrix for injecting information of one of the input data streams into the encoding of another one of the input data streams.

Abstract: A data encoding algorithm can be used (120) to generate overhead bits from original data bits, and the original data bits and overhead bits can be transmitted in respectively separate transmissions (121, 123), if the overhead bits are needed. At the receiver, the original data bits can be determined (125) from the received overhead bits, or the received data bits and the received overhead bits can be combined and decoded together (126) to produce the original data bits.

Abstract: A method of resetting a trellis-coded modulation (TCM) encoder to a known state, the TCM encoder including a reset input that resets the TCM encoder to the known state when held at a reset level for a plurality of symbol clock cycles, the method including identifying an event to occur in the future that requires the TCM encoder to be reset to the known state; and holding the reset input of the TCM encoder at the reset level beginning the plurality of clock symbol cycles before a time the event will occur so that the TCM encoder will be reset to the known state immediately before the event occurs.

Abstract: A method of calculating at least one soft bit corresponding to a data symbol received by a radio receiver is described. In one form the method (300) includes, calculating an average amplitude at least one received data symbol. The method also includes calculating (304) at least one threshold amplitude in respect of the data symbol on the basis of the calculated average amplitude. Next a subset of constellation symbols is determined (310) at least partly on the basis of the at least one threshold, and for which a distance determination will be made. The distance between the position of the data symbol and each of the symbols in the subset of constellation symbols is determined (312) and then a soft bit corresponding to the received symbol is calculated (314) on the basis of said determined distances.

Abstract: Method and apparatus for high rate code-division multiple access wireless communication is described. Each of a channel encoded data is modulated by an associated code having a small number of pseudo-noise spreading chips per orthogonal waveform period, thus producing a set of streams of modulated symbols. Each of the set of streams of modulated symbols is then gain adjusted, and combined to yield two streams of combined symbols. The combination is the set of streams is carried out to reduce a peak-to-average ratio of the transmission. The resulting two combined symbol streams are modulated by a complex multiplyer using a user long code and a pseudorandom spreading code (PN code) and upconverted for transmission.

Abstract: A method of transmitting data by transmitting apparatus, that includes controlling generation of bit sequences to adjust an occupation rate of systematic bits in a first data block including systematic bits and parity bits, which is obtained by encoding first data in a first encoding process, and is equal or closer to an occupation rate of systematic bits in a second data block including systematic bits and parity bits, which is obtained by encoding second data in a second encoding process, and to adjust an occupation rate of parity bits in the first data block that is closer to an occupation rate of parity bits in the second data block, in regard to first bit positions of the bit sequences generated using bits included in the first and second data blocks and performs multi-level modulation for transmission based on the generated bit sequences.

Abstract: A digital broadcast transmitting/receiving system and a method for processing data are disclosed. The method for processing data may enhance the receiving performance of the receiving system by performing additional coding and multiplexing processes on the traffic information data and transmitting the processed data. Thus, robustness is provided to the traffic information data, thereby enabling the data to respond strongly against the channel environment which is always under constant and vast change.

Abstract: A method and apparatus for performing trellis coded modulation of signals for transmission on a TDMA channel of a cable network, such as a DOCSIS cable network, is provided. In an embodiment, an upstream modulator portion of a cable modem receives burst data, selectively encodes the burst data for trellis coded modulation to generate encoded symbols, and modulates the encoded symbols for selective transmission over a time division multiple access (TDMA) channel or a synchronous code division multiple access (S-CDMA) channel of the cable network.

Abstract: Teachings presented herein offer reduced and stable computational complexity for symbol block detection using multi-stage assistance, and also provide for the generation of soft bit values. A demodulator generates these soft bit values by forming from a set of candidate symbol combinations, for each group of symbols in a symbol block, a subset of candidate symbol combinations for that group. The demodulator selects from the set the most likely combination, at least one combination that has a complementary bit value for a respective bit value in the most likely combination, and as many of the next most likely combinations not already selected as are needed for the size of the subset to conform to a pre-determined size. The demodulator generates soft bit values by limiting the candidate combinations of symbols considered for a symbol block according to the subsets formed for the groups of symbols in that symbol block.

Abstract: A digital broadcast transmitting/receiving system and a signal processing method thereof that can improve the receiving performance of the system. A digital broadcast transmitter has a randomizer to randomize an input data stream which has null bytes being inserted at a specified position, a multiplexer to output a data stream formed by inserting specified known data into the position of the null bytes of the randomized data stream, an encoder to encode the data stream outputted from the multiplexer, and a modulator/RF-converter to modulate the encoded data, RF-convert the modulated data and transmit the RF-converted data. The receiving performance of the digital broadcast transmitting/receiving system can be improved even in a multi-path channel by detecting the known data from the received signal and using the known data in synchronization and equalization in a digital broadcast receiver.

Abstract: A method and a system for decoding information signals encoded in accordance with a multi-state encoding scheme and transmitted over a multi-dimensional transmission channel by computing a distance of a received word from a codeword. One-dimensional (1D) input signals are processed in a pair of symbol decoders, implemented as look-up tables, to produce a pair of 1D errors, with each representing a distance metric between the input signal and a symbol in one of two disjoint symbol-subsets. The 1D errors are combined based on the multi-state encoding scheme in order to produce a set of multi-dimensional error terms. Each of the multi-dimensional error terms corresponds to a distance between a received word and a nearest codeword.

Abstract: A method and a device (4) for block interleaving of size K with N iterations of index j, N being greater than or equal to 1, of input digital data items indexed by a variable k={0, . . . , K?1}. The interleaving method uses a turbo structure that has two inputs and one output. At the end of each iteration j, the interleaving law I(j)(k) at the output of the interleaver (4) is modified in accordance with an input sequence formed by the position indices of the data items before interleaving (typically a ramp) and in accordance with an interleaved sequence (which provides the position of the data items after interleaving) resulting from the previous iteration of the same interleaving algorithm.