Method and detector for a novel channel quality indicator for space-time encoded MIMO spread spectrum systems in frequency selective channels

摘要

In a jointly encoded (JE), spread spectrum communication MIMO system where a demultiplexed packet is transmitted over multiple streams, two versions of a single channel quality indicator (CQI) is disclosed: generalized SNR or constrained mutual information CMI between the transmitted and received chip vectors. In the receiver, the CMI is constrained so that filtering is suboptimal. The filter bank is preferably LMMSE or MVDR filters that convert the multi-path channel into a single path channel so that joint sequence detection is unnecessary. Detection is instead by a per-Walsh code architecture, wherein a plurality of Walsh-code specific detectors in parallel detect bits or symbols from the single-channel chips after downconverting chip to symbols. Link to system mapping is realizable using the disclosed CQI for a JE MIMO system in that the CQI or related information is returned to the transmitter, which adapts coding rate and/or modulation for the channel as represented by the CQI.