Lucent Technologies Inc.

Agere Systems Guardian Corp.

Rudiger L Urbanke

Thomas J Richardson

Hui-Ling Lou

Rajiv Laroia

Bertrand Martyn Hochwald

Thomas L Marzetta

Adriaan J De Lind Van Wijngaarden

Wim Sweldens

Bharat P Dave

Vijitha Weerackody

Brij Bhushan Garg

James S Lavranchuk

Boris B Stefanov

Aaron Daniel Wyner

Error control coding is applied to data streams transmitted through transmission equipment such as a telecommunications switch having a distributed synchronous switch fabric. Each k-symbol dataword is encoded to generate an n-symbol codeword that is then sliced for transmission through the transmission equipment. After routing, error-correction decoding is applied to the resulting routed n-symbol codeword to detect and correct one or more errors in the codeword to generate a k-symbol routed dataword that is identical to the original incoming dataword. Depending on the coding scheme, different types and numbers of errors can be corrected in each codeword. For example, for Reed-Solomon &lsqb;12, 8, 5&rsqb; coding with Galois field (2 ), corrections can be made for up to four erasures with no random errors, up to two erasures and one; random error, or up to two random errors with no erasures. In this way, error-less fault tolerance can be provided that ensures the accuracy of transmission processing in the event of certain combinations of errors. Preferred embodiments involve temporal sharing of components (for more cost effective implementations) and shuffling of data (to increase error-correction coverage).

Error control coding for transmission equipment protection

First and second source signal streams each associated with a program source are produced. A first error correction code having a first correction delay is applied to the first source signal stream, thus producing a first error-corrected source signal stream that is transmitted for reception by a receiver. A tuning signal stream corresponding to the second source signal stream is transmitted for reception by the receiver at a determined timing relative to transmission of the first error-corrected signal stream. When first tuning to a program transmission channel, the receiver initially processes the tuning signal to obtain at least a recognizable reproduction of the program source, with little if any delay attributable to error correction coding of the first source signal stream.

Tuning scheme for error-corrected broadcast programs

Messages according to a method of wireless signal transmission are sent as sequences of unitary space-time signals. Each signal is representable as a matrix in which each column represents a respective transmitting antenna of a transmitting array, and each row represents a time segment. Each such matrix is proportional to a complex-valued matrix, all columns of which are mutually orthonormal. A new method for creating a constellation of signal matrices comprises providing an initial signal in the form of a complex, orthonormal matrix. The method further comprises generating a further plurality of matrices by a process that assures that each of the generated matrices is related to the initial matrix as a product of one or more multiplications of the initial matrix by one or more unitary matrices.

Wireless transmission method for antenna arrays using unitary space-time signals

A communication system decoder in which branch metrics are represented using linear distance. An illustrative embodiment for decoding a sequence of received symbols of a QPSK or QAM constellation includes a branch metric calculation unit, an add-compare-select unit, and a traceback unit. The branch metric unit computes branch metrics associated with transitions between states of a multi-stage trellis representation of a state machine. In accordance with the invention, each of the branch metrics correspond to a linear distance between a given one of the received symbols and its nearest codeword in a given stage of the trellis. The add-compare-select unit utilizes the branch metrics of a current stage, along with a previously-generated path metric, for comparison purposes in determining a survivor path and corresponding updated path metric for a current stage of the multi-stage trellis. The traceback unit utilizes the updated path metric to generate a corresponding decoded output. Advantageously, the add-compare-select unit of the decoder is configured such that it achieves a level of performance using the linear distance branch metrics which is equivalent to that achieved using squared distance branch metrics, while also substantially reducing the decoder complexity through the elimination of multiplication operations.

Methods and apparatus for representation of branch metrics in a communication system decoder

We describe an improved method for decreasing the probability of an unacceptably high peak-to-average power ratio in a signal to be transmitted by a Frequency Division Multiplexing (FDM) system, such as a discrete multitone (DMT) system. The method involves generating at least two alternative signal sequences, computing Fourier transforms of the respective alternative signal sequences, and selecting for transmission one of these sequences, based on the Fourier transform computations. More specifically, the selection of one sequence may be based, e.g., on the determination that the Fourier transform of that sequence has an acceptable peak power. Alternatively, a comparison may be made among the Fourier transforms of the respective signal sequences, and selection made of that sequence whose Fourier transform exhibits the lowest peak power.

Communication method for frequency division multiplexing signalling systems with reduced average power requirements

A system for transmitting data over an erasure channel. A data block is divided into coarse and fine segments. The coarse segment is encoded using an error-correcting encoding process. The fine segment and the encoded coarse segment are combined and divided into packets, and the packets are transmitted over the erasure channel. When the data is received, the coarse segment is decoded. If data packets were lost during transmission, the coarse segment is reconstructed as the received data block. If no packets were lost, the fine segment is combined with the coarse segment and the entire data block as originally transmitted is reconstructed. For large numbers of packets, the system invention can achieve any point within the capacity region of an erasure channel.

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Murray Hill, NJ, United States of America

Rudiger L Urbanke