Soft cancellation of inter-layer interference within a MIMO codeword

A method of removing interference from a received signal encoded with a codeword and mapped to two layers, comprising the steps of:

• equalizing the received signal by at least one of a first and a second equalizer;
• demodulating the equalized signal;
• decoding the demodulated signal by extracting soft bits from the demodulated signal, wherein each soft bit comprises a probabilistic estimate of a value of a corresponding bit of the received signal;
• modulating the decoded signal by generating soft symbols based on the extracted bits, wherein each soft symbol represents a probabilistic estimate of a value of a corresponding symbol in the received signal;
• demapping the modulated signal to soft symbols corresponding to each of the two layers;
• and
• cancelling interference from a second one of the two layers by a first inter-layer interference canceller utilizing the demapped soft symbols corresponding to the second layer.

An apparatus for cancelling inter-codeword and inter-layer interference comprising:

• a first receiver and a second receiver wherein each receiver processes signals encoded with a respective codeword and mapped to two layers and each receiver comprises:
• two equalizers for equalizing the received signal;
• two demodulators for demodulating the respective equalized signal;
• a decoder for decoding the demodulated signal by extracting soft bits from the respective demodulated signals, wherein each soft bit represents a probabilistic estimate of a value of a corresponding bit in the received signal;
• a modulator for modulating the decoded signal by generating soft symbols based on the extracted soft bits, wherein each soft symbol represents a probabilistic estimate of a value of a corresponding symbol in the received signal;
• a demapper for demapping the modulated signal to soft symbols corresponding to each of the two layers;
• and
• two inter-codeward and inter-layer interference cancellers (ICILICs) for cancelling inter-codeword and inter-layer interference utilizing the demapped soft symbols, wherein
• a first of the ICILICs in the first receiver cancels inter-layer interference utilizing the demapped soft symbols corresponding to a second one of the two layers in the first receiver.

A receiver for processing a received signal encoded with a codeword and mapped to two layers comprising:

• a first and a second equalizer for equalizing the received signal;
• a plurality of demodulators for demodulating a respective equalized signal;
• a decoder for decoding the demodulated signal by extracting soft bits from the demodulated signal, wherein each soft bit comprises a probabilistic estimate of a value of a corresponding bit of the received signal;
• a demapper for demapping the decoded signal to soft bits corresponding to each of the two layers;
• a first and a second modulator for modulating the demapped soft bits associated with each of the two layers by generating soft symbols based on the demapped soft bits, wherein each soft symbol represents a probabilistic estimate of a value of a corresponding symbol in the received signal;
• and
• a first and a second inter-layer interference canceller for cancelling interference utilizing the generated soft symbols, wherein
• the demapper provides soft bits associated with a first one of the two layers to the first modulator;
• the first modulator provides soft symbols associated with the first layer to the first equalizer and to the second interlayer interference canceller;
• the first equalizer utilizes the first layer soft symbols to reduce inter-symbol interference, and
• the second interlayer interference canceller utilizes the first layer soft symbols to reduce interference from the first layer.

A method of removing interference from a received signal encoded with a codeword and mapped to two layers, comprising the steps of:

• equalizing the received signal by at least one of a first and a second equalizer;
• demodulating the equalized signal;
• decoding the demodulated signal by extracting soft bits from the demodulated signal, wherein each soft bit comprises a probabilistic estimate of a value of a corresponding bit of the received signal;
• demapping the decoded signal to soft bits corresponding to each of the two layers;
• modulating the demapped soft bits associated with each of the two layers by generating soft symbols based on the demapped soft bits, wherein each soft symbol represents a probabilistic estimate of a value of a corresponding symbol in the received signal;
• and
• cancelling inter-layer interference utilizing the generated soft symbols;
• cancelling inter-symbol interference by the second equalizer utilizing soft symbols corresponding to a second one of the two layers;
• and
• cancelling interference from the second layer by a first inter-layer interference canceller utilizing the second layer soft symbols.