Bit sharing for layered space-time architectures with ordered signal retrieval

The paper describes a novel encoding strategy for the existing layered space-time architectures used in multiple-element antenna (MEA) transmission systems. Layered architectures like V-BLAST regard a MEA channel as a set of independently encoded mutually interfering scalar channels (layers) which are decoded subsequently, so that a hefty fraction of the total MEA capacity may be achieved with a moderate complexity proportional to the number of transmit antennas. Practically achievable rates are, however, limited by the minimum of the outage throughputs taken over all layers. Usually, this limitation is overcome due to a joint encoding/decoding of different layers, resulting in a substantial increase in decoding complexity. The encoding strategy described allows leveraging this limitation in some cases of practical interest, without altering the existing space-time processing schemes. Numerical analysis confirms the high potential of this approach in the case of small outage rates.