Superposition Coding in Alternate DF Relaying Systems with Virtual MIMO IRI Cancellation

摘要

This paper considers a layered transmission between the source and the destination aided by two half-duplex relays. In the proposed system, the single antenna source continuously broadcasts superposition coded (SC) base and enhancement layers, while relays, with one active antenna, retransmit in turn the enhancement layer. Using two antennas, the destination as well as the relays receive mixed base, enhancement, and delayed enhancement layers through over-the-air signal summation. To recover from inter-relay interference (IRI), the receiving relay decouples two spatial streams representing data of interest using the virtual Multiple Input Multiple Output (MIMO) channel from the source and the transmitting relay. Because of the network topology, the receiver deploys both virtual MIMO and Successive Interference Cancellation (SIC) techniques to first decode the delayed enhancement layer and then the delayed base layer. In this decode-and-forward (DF) transmission scheme, the transmissions from the source and the relays are aligned in time, power, and spatial domains to optimize the system throughput and reliability. Finally, this paper demonstrates that the SC with alternate relaying in the proposed single input multiple output (SIMO) setup has a better performance than similar conventional schemes.