Methods and apparatus for equalization and decoding of digital communications channels using antenna diversity
AssigneeLucent Technologies Inc.
InventorsStephen Russell Huszar, Nambirajan Seshadri
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Abstract
An equalizer/decoder for a communication channel presenting impairments to error-free reception of transmitted symbols includes a modified Viterbi decoder operating on samples of received signals in a plurality of equivalent subchannels. Estimates of each of the subchannels are updated using a locally best estimate in the Viterbi trellis processing, thereby avoiding delay in updating channel estimates in a rapidly changing channel such as a digital cellular communications channels. A leaky predictor channel updating technique also proves advantageous in an alternative embodiment.
Claims28
A method for decoding a time varying signal representing a sequence of symbols having been supplied to a communications channel at a symbol rate, said method comprising the steps of:
- receiving said time varying signal at each one of a plurality of antennas;
- sampling said received time varying signal at a sampling rate of R/T, wherein R.gtoreq.2, and generating a set of R sampled values representative of said sampled time varying signal at each of said plurality of antennas;
- generating locally a set of values for each one of a plurality of sets of candidate symbol sequences, each of said values representing at least a partial estimate of an output of said communications channel as received at least one of said plurality of antennas;
- and
- comparing each of said sample sets with one or more of said value sets and, in response thereto, selecting the sequence of symbols supplied to said communications channel and received at at least one of said plurality of antennas.
A decoder for decoding a time varying signal representing a sequence of symbols having been supplied to a communications channel at a symbol rate, said decoder comprising:
- a plurality of antennas operative to receive said time varying signal;
- and
- a circuit coupled with said plurality of antennas and operative to:
- sample said received time varying signal at a sampling rate of R/T wherein R.gtoreq.2, and generate a set of R sampled values representative of said sampled time varying signal at each of said plurality of antennas;
- generate a set of values for each one of a plurality of sets of candidate symbol sequences, each said value representing at least a partial estimate of an output of said communications channel as received at at least one of said plurality of antennas;
- and
- compare each of said sample sets with one or more of said value sets and, in response thereto, select the sequence of symbols supplied to said communications channel and received at at least one of said plurality of antennas.
Dependencies are inferred from the claim text.