In this paper, we consider a MIMO wireless relay
network where communication between a source and a destination
node is assisted by multiple relay nodes using the Amplifyand-
Forward (AF) strategy. We consider a system where the
source node multiplexes the information into parallel streams
and uses disjoint subsets of relays to assist the transmission of
each stream. Furthermore, we assume that the source and the
destination have the same number of antennas and that each
transmit antenna is virtually paired to a different destination
antenna. We consider source node channel side information (CSI)
availability of just the source-relay and source-destination links,
and propose a source beamforming method based on maximizing
the Sum of Signal-to-Leakage Ratios (SSLR) for all of the data
streams. This method maximizes the sum of signal strengths at
the set of relay nodes assigned to that stream while suppressing
the interference to other relay nodes. Maximizing the SSLR
reduces the propagation of interference terms in the AF strategy
and results in signicant performance gains.
