Date Added: Jun 2010
This paper proposes a Minimum Mean-Square-Error Bi-directional Amplify-and-Forward (MMSEBAF) relaying protocol for multi-hop wireless networks employing multi-antenna relays. MMSEBAF is a two-phase relaying protocol which allows for two sources to exchange independent messages via a relay node equipped with multiple antennas. The latter performs a joint linear MMSE filtering of the received signal after the Multiple Access (MA) phase before amplifying and forwarding using a single transmit antenna, possibly through a specific antenna selection procedure, during the broadcast phase. The proposed MMSE-BAF protocol extends upon the so-called analog network coding schemes in the literature in that it inherently exploits the multiple antennas.