Turbo Receiver Design for MIMO Relay ARQ Transmissions

In this paper, the authors investigate practical turbo receiver design for throughput-efficient relay ARQ transmissions over broadband cooperative MIMO channels. Their setup is comprised of three multi-antenna nodes: a source, a destination, and a relay node operating under the amplify-and-forward half-duplex relaying mode. To attain higher system average throughput, they adopt a two-slot transmission strategy where the ARQ mechanism is activated on top of the amplify-and-forward protocol. They derive a soft sub-packet combiner allowing the destination node to jointly perform sub-packet combining (over both time-slots and multiple ARQ rounds) and Frequency Domain (FD) MMSE filtering.