Method and apparatus for joint detection of a coded signal in a CDMA system
AssigneeMotorola, Inc.
InventorXiaoyong Yu
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Abstract
The present invention addresses the deficiencies of prior art joint detection techniques by implementing the decision feedback equalizer part of a joint detector in the turbo decoding iteration loop such that joint detection and turbo decoding are performed interactively in a mutual support fashion. Thus, the decoder (230) benefits from ISI and MAI suppressed samples provided by the equalizer, while the decision feedback equalizer is fed with more reliable hard decisions for the transmitted symbols by the turbo decoder.
Claims15
A method for joint detection of a coded input signal in CDMA system comprising:
- slicing the coded input signal to generate a first undesired signal;
- subtracting the first undesired signal from the coded input signal to produce a first decoder input signal;
- demultiplexing the first decoder input signal to produce a plurality of decoder input signal portions, each of which corresponds to a decoder of a plurality of decoders;
- decoding, by each decoder of the plurality of decoders, the corresponding decoder input signal portion to produce a first set of recovered symbols;
- generating a second undesired signal from the first set of recovered symbols;
- subtracting the second undesired signal from the coded input signal to produce a second decoder input signal;
- demultiplexing the second decoder input signal to produce a second plurality of decoder input signal portions, each of which corresponds to a decoder of the plurality of decoders;
- and
- decoding, by each decoder of the plurality of decoders, the corresponding decoder input signal portion of the second plurality of decoder input signal portions to produce a second set of recovered symbols.
A CDMA joint detector apparatus comprising:
- a signal adder capable of adding a first undesirable signal to an input signal to produce a decoder input signal;
- a plurality of decoders, wherein each decoder is capable of decoding a portion of the decoder input signal to produce recovered symbols;
- a demultiplexer, coupled to the signal adder and the plurality of decoders, capable of feeding each portion of the decoder input signal to a corresponding decoder of the plurality of decoders;
- a recovered symbols buffer, coupled to the plurality of decoders, capable of storing the recovered symbols;
- a selector, coupled to the recovered symbols buffer;
- a signal generator, coupled to the adder and the recovered symbols buffer via the selector, capable of generating a second undesired signal from the recovered symbols for addition to the input signal to produce a second decoder input signal when the recovered symbols buffer is selected by the selector;
- and
- a slicer, coupled to the adder via the selector, capable of slicing an adder output signal to produce the first undesirable signal via the signal generator when selected by the selector.
Dependencies are inferred from the claim text.