Agere Systems Inc.

Lisa Fredrickson

Leilei Song

Bomey Yang

A simplified Viterbi detector for maximum likelihood detection of nine-bit QPSK symbols, employing a difference metric and two comparators, instead of using two state metrics and four comparators. The detector is used to process the outputs of synchronously sampled matched filters. A multiplexer is employed to select the difference metric from amongst the input sample, the fed back value of the difference metric itself, or the inverses of either, depending on decision signals output from the comparators, which in turn compare the difference metric with the input sample and it's inverse. The even path history then represents the most likely value of the detected symbol.

Simple detector and method for QPSK symbols

A Reed Solomon decoder architecture that uses a modified version of the error-evaluator polynomial form having a significantly reduced area of the dominant PDU unit, without loss in iteration time, in slice circuitry, which rotates terms to share a common multiplier and other circuitry. In addition, a B polynomial is stored, and associated overflow flags are implemented, to allow its storage to be minimized using a dual-multiplier arrangement. The decoder for error correcting codes comprises a syndrome calculation circuit, and a polynomial determining unit comprising slices, and a single multiplier in each of the slices, wherein each of the slices is employed a plurality of times in successive clock cycles. A correction circuit comprises a first multiplier employed when a scratch polynomial has overflowed, and a second multiplier employed when not overflowed.

Decoder architecture for reed solomon codes

Reed-Solomon encoders providing support for multiple codes in a simple architecture having a reduced number of Galois field multipliers. Rather than implementing n subfilters each representing an individual degree polynomial filter as in conventional Reed-Solomon encoder, multiple degree polynomials are factored in a way which is convenient to a desired plurality of Reed-Solomon codes. Thus, not only are the number of required Galois field multipliers reduced, but support for different Reed-Solomon codes is provided with a minimized number of Galois field multipliers. Preferred embodiments in compliance with the proposed 802.16.1 wireless standard support up to sixteen Reed-Solomon codes all within a single architecture, including sixteen subfilters, either cascaded or in parallel. Each of the individual filters balances and reduces critical path lengths in the Reed-Solomon encoder, and reduces the loading of critical nets, resulting in a Reed-Solomon encoder with a greater throughput for a given technology.

High throughput Reed-Solomon encoder

The present invention provides for smaller, faster Reed-Solomon encoders, while at the same time providing support of multiple codes in a simple architecture having a reduced number of Galois field multipliers. In accordance with the principles of the present invention, a polynomial is factored differently than conventional Reed-Solomon encoders, resulting in enhanced performance, simplified circuitry, and/or a reduction of critical paths in the Reed-Solomon encoders. Thus, not only are the number of required Galois field multipliers reduced, but support for three different Reed-Solomon codes is provided with a minimized number of Galois field multipliers. In the disclosed embodiments, rather than implementing n subfilters each representing an individual degree polynomial filter as in Cox's conventional Reed-Solomon encoder, the present invention implements multiple degree polynomials factored in a way which is convenient to a desired plurality of Reed-Solomon codes. The polynomials may be divided into any degree subtrunks convenient for the particular application. One preferred embodiment supports up to three Reed-Solomon codes all within a single architecture, comprising only three cascaded filters. Each of the individual filters balances and reduces critical path lengths in the Reed-Solomon encoder, and reduces the loading of critical nets, resulting in a Reed-Solomon encoder with a greater throughput for a given technology. For instance, the conventional Cox taught Reed-Solomon encoder would require, e.g., 24 subfilters to provide n bytes of redundancy, each subfilter having polynomial having a single degree. However, in accordance with the principles of the present invention, three different Reed-Solomon codes may be provided (e.g., 14 bytes of redundancy, 22 bytes of redundancy, or 24 bytes of redundancy), by cascading three multiple degree polynomial subfilters (e.g., a first subfilter of degree 14, a second subfilter of degree 8, and a third subfilter of degree 2).

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Long Beach, CA, United States of America

Lisa Fredrickson