We consider "virtual" full-duplex relaying by means of half-duplex relays. Inthis configuration, each relay stage in a multi-hop relaying network is formedby at least two relays, used alternatively in transmit and receive modes, suchthat while one relay transmits its signal to the next stage, the other relayreceives a signal from the previous stage. With such a pipelined scheme, thesource is active and sends a new information message in each time slot. Weconsider the achievable rates for different coding schemes and compare themwith a cut-set upper bound, which is tight in certain conditions. Inparticular, we show that both lattice-based Compute and Forward (CoF) andQuantize reMap and Forward (QMF) yield attractive performance and can be easilyimplemented. In particular, QMF in this context does not require "long"messages and joint (non-unique) decoding, if the quantization mean-squaredistortion at the relays is chosen appropriately. Also, in the multi-hop casethe gap of QMF from the cut-set upper bound grows logarithmically with thenumber of stages, and not linearly as in the case of "noise level"quantization. Furthermore, we show that CoF is particularly attractive in thecase of multi-hop relaying, when the channel gains have fluctuations not largerthan 3dB, yielding a rate that does not depend on the number of relayingstages. In particular, we argue that such architecture may be useful for awireless backhaul with line-of-sight propagation between the relays.
展开▼
