US 7,154,936 B2 · Iterative detection and decoding for a MIMO-OFDM system

Abstract

Techniques to iteratively detect and decode data transmitted in a wireless (e.g., MIMO-OFDM) communication system. The iterative detection and decoding is performed by iteratively passing soft (multi-bit) “a priori” information between a detector and a decoder. The detector receives modulation symbols, performs a detection function that is complementary to the symbol mapping performed at the transmitter, and provides soft-decision symbols for transmitted coded bits. “Extrinsic information” in the soft-decision symbols is then decoded by the decoder to provide its extrinsic information, which comprises the a priori information used by the detector in the detection process. The detection and decoding may be iterated a number of times. The soft-decision symbols and the a priori information may be represented using log-likelihood ratios (LLRs). Techniques are provided to reduce the computational complexity associated with deriving the LLRs, including interference nulling to isolate each transmitted signal and “dual-maxima” approximation.

Claims42

Dependent claims

A method for recovering data transmitted in a wireless communication system, wherein the wireless communication system comprises a plurality of receive antennas, comprising:

receiving at least one data stream, wherein each data stream comprises a plurality of modulation symbols for a plurality of transmitted coded bits;
wherein the plurality of modulation symbols for each receive antenna is a respective modulation or coding scheme;
determining for each data stream a plurality of soft decision symbols based on the received plurality of modulation symbols and a first a priori information for the transmitted coded bits;
determining a second a priori information based on the plurality of soft decision symbols and the first a priori information for the transmitted coded bits;
determining the first a priori information for the transmitted coded bits based in part on the second a priori information;
repeating the determining the plurality of soft decision symbols and the determining the first a priori information and a plurality of times;
determining decoded bits for the transmitted coded bits based on the second a priori information.

4 more elements

A receiver unit in a wireless communication system, wherein the wireless communication system comprises a plurality of receive antennas, comprising:

a detector operative to receive at least one data stream, wherein each data stream comprises a plurality of modulatian symbols for a plurality of transmitted coded bits, derive soft-decision symbols for the coded bits based on the received modulation symbols and a first a priori information for the coded bits derive the first a priori information for the coded bits based on a a posteriori information, and derive a second a priori information for the coded bits based on the soft-decision symbols and the first a priori information;
wherein the detector operative to receive the plurality of modulation and symbols from each receive antenna with a respective modulation or coding schemes;
a decoder operative to decode the second a priori information to derive the a posteriori information and to determine decoded bits of the transmitted coded bits;
and
wherein the second a priori information is derived by the detector and decoded by the decoder a plurality of times prior to determining the decoded bits.

2 more elements

A receiver apparatus in a wireless communication system, wherein the wireless communication system comprises a plurality of receive antennas, comprising:

means for receiving at least one data stream, wherein each data stream comprises a plurality of modulation symbols for a plurality of coded bits transmitted via a plurality of frequency subchannels of the plurality of transmit antennas, wherein the plurality of modulation symbols for each receive antenna is a respective modulation or coding scheme;
means for deriving soft-decision symbols for the coded bits based on the received modulation symbols and a first a priori information for the coded bits;
means for deriving a second a priori information for the coded bits based on the soft-decision symbols and the first a priori information;
first means for decoding the second a priori information to derive the first a priori information, wherein the second a priori information is derived and decoded a plurality of times;
and
first means for determining decoded bits of the transmitted coded bits based in part on the first a priori information.

3 more elements

Dependencies are inferred from the claim text.

Iterative detection and decoding for a MIMO-OFDM system

Life of this patent

Iterative detection and decoding for a MIMO-OFDM system

Life of this patent

Abstract

Claims42