Outage based power allocation for a lossy forwarding two-relaying system

The extension of Decode-and-Forward (DF) relaying by lossy forwarding has the potential to ensure a reliable multi-hop message transport in wireless mesh networks. Unlike in conventional DF relaying, with lossy forwarding a relay forwards a message regardless whether errors have been detected after decoding. At the destination, a proper joint decoding technique exploits the high correlation of messages received via different network paths. According to the Slepian-Wolf correlated source coding theorem a performance improvement compared with the conventional DF relaying can be expected. The performance can be optimized by a power allocation scheme that distributes the total transmit power budget between source and relay nodes. This paper analyzes the outage probability (OP) based on the Slepian-Wolf source correlation theorem for a system with two relays and designs a power allocation scheme to minimize the OP. The proposed scheme reduces the OP by up to 1.5 orders of magnitude compared to the reference case of equal power allocation. We also compare the performance gain of a system with two relays against the case with a single relay for the same total transmit power budget. Results show a reduction of the OP of at least one and up to two orders of magnitude.