General Instrument Corporation of Delaware

Cornell University

General Instrument Corporation

Gi, LLC

Codenoll Technology Corporation

Chris Heegard

Woo H Paik

Scott A Lery

David J Rowe

Thomas J Kolze

Edward A Krause

Jerrold A Heller

Stephen K How

Zheng Huang

Andrew J King

Sydney Lovely

A concatenated trellis coded modulation and linear block (e.g., Reed-Solomon) encoding scheme splits data to be encoded into two data streams, one of which is both linear block encoded and trellis encoded, and the other of which either remains uncoded or is encoded with a weaker strength linear block code. The coding scheme requires the use of a special decoder which decodes the trellis encoded data first, and then uses the resulting information to decode the non-trellis encoded information. In embodiments using linear block coding for the non-trellis encoded data stream, the relative strengths of the two linear block encoders are selected to balance the resulting code, thereby maximizing coding gain and efficiency.

Concatenated trellis coded modulation and linear block codes

An N-bit, byte-wise data randomizer uses a linear feedback shift register arrangement where each register stage stores N-bits. In this manner, a pseudorandom sequence can be generated based on a nonbinary primitive polynomial over a finite field of any desired length. In a specific disclosed embodiment, the primitive, degree three trinomial

Randomizer for byte-wise scrambling of data

A method and apparatus are provided for achieving synchronization and detecting errors in a data stream such as an MPEG-2 transport packet stream. In an MPEG embodiment, the MPEG sync word is removed and replaced with a parity code that is used at the decoder for both synchronization and error detection. A syndrome calculator in the decoder can be implemented using a unique one bit in, one bit out FIR filter. Codewords used to generate the parity code can be provided by a linear block code that is a dual of a shortened cyclic code.

Synchronization and error detection in a packetized data stream

A rotationally invariant trellis coder is provided for encoding data to be transmitted using a two-dimensional symbol modulation. A precoder, provided at the transmitter, processes data such that a counterpart postcoder at the receiver will provide an output that is invariant to any multiple of a 90.degree. rotation. An encoder encodes the precoded data using a transparent binary convolutional code, which can be a punctured or unpunctured code. The encoded data is mapped to a two-dimensional signal space having a plurality of signal points. The signal points are labeled with unique binary codes in which the two least significant bits, denoted by (I.sub.j, Q.sub.j), are permuted and partially complemented to (Q.sub.j, I.sub.j) for each 90.degree. phase rotation around the signal space. The remaining most significant bits for each point, if any, are invariant to such rotation. The postcoder provided at the receiver inverts the precoder and is feedback-free, thus limiting error propagation.

Rotationally invariant trellis coding incorporating transparent binary

A method and apparatus are provided for convolutionally encoding digital data with a rate 4/5 convolutional code. A nonoptimal rate 1/2, sixteen-state convolutional code is punctured to rate 4/5 using a puncture map of ##EQU1## and octal generators 25, 37 wherein .nu.=4. An incoming data stream is processed using the rate 4/5 code. Punctured rate 3/4 and 6/7 codes are also provided.

Punctured convolutional encoder

An outer symbol error correcting code is concatenated with a punctured multidimensional trellis code to provide an optimal scheme for communicating digital television signals in a standard (e.g., approximately six MHz) bandwidth channel via a cable television network or the like. An input signal is encoded using an outer symbol error correcting code to produce successive blocks. Each block comprises N seven-bit coded symbols of which M represent information to be communicated and the remaining N-M coded symbols comprise error correcting information. M/N is either 120/126, 121/127 or 122/128. The blocks are interleaved, and may be supplemented with control symbols that include a synchronization pattern for M/N=121/127 or M/N=122/128. The interleaved blocks are convolutionally encoded using an inner trellis code having a punctured rate 4/5 (sixty-four QAM) or 3/4 (sixteen QAM). The output symbols are multilevel modulated for transmission over a communication path using, for example, sixteen or sixty-four QAM. The transmitted symbols are decoded using a trellis decoder, deinterleaved, and further decoded in an outer symbol error decoder concatenated with the inner trellis decoder.

Quadrature amplitude modulated data for standard bandwidth television

A method and apparatus for communicating high definition television signals is provided. Video signals are divided into blocks of PCM data. The PCM data is processed using motion estimation and compensation to provide DPCM data. For each block, one of PCM and DPCM data is selected for transmission based on a predetermined criteria. The selected data is compressed using the discrete cosine transform to provide blocks of transform coefficients. The coefficients are quantized to improve their coding efficiency and variable length coded. The variable length coded coefficients are coded using a concatenated coding scheme with a Reed-Solomon outer code and trellis inner code to provide coded signals for transmission. The coded signals are transmitted using QAM.

Method and apparatus for communicating digital information such as

Coded modulation schemes based on codes for QPSK modulation are directly incorporated into QAM based modulation systems, forming trellis coded QAM for communicating information. Concatenated coding with QPSK based trellis coding and symbol error correcting coding is used. In an encoder, an N-bit QAM constellation pattern is divided into four subsets, each including N/4 symbol points of the constellation pattern. A two-bit QPSK codeword is assigned to each of the four subsets. A symbol to be transmitted is first encoded using an outer error correcting encoding algorithm. Part of the symbol is then encoded with an inner code that comprises a rate 1/2 trellis encoding algorithm to provide a QPSK codeword, which is mapped with the remaining bits of the symbol to provide a modulation function. The remaining bits correlate the symbol with one of the symbol points included in the subset defined by the QPSK codeword. A receiver is provided to recover information from the modulation function.

Method and apparatus for communicating digital data using trellis coded

A collision detection method and apparatus is disclosed for detecting code rule violations in Manchester encoded data packets. The signals

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Chris Heegard