Overloaded MIMO Bi-Directional Communication With Physical Layer Network Coding in Heterogeneous Multihop Networks

SUMMARY This paper proposes overloaded multiple input multiple output (MIMO) bi-directional communication with physical layer network coding(PLNC)toenhancethetransmissionspeedinheterogeneouswireless multihopnetworkswherethenumberofantennasontherelayislessthanthatontheterminals.TheproposedoverloadedMIMOcommunicationsystem appliesprecodingandrelayfilteringtoreducecomputationalcomplexityinspiteofthetransmissionspeed.Aneigenvector-basedfilterisproposed fortherelayfilter.Furthermore,weproposeatechniquetoselectthebestfilteramongcandidateseigenvector-basedfilters.Theperformanceof theproposedoverloadedMIMObi-directionalcommunicationisevaluatedbycomputersimulationinaheterogeneouswireless2-hopnetwork.The proposedfilterselectiontechniqueattainsagainofabout1 . 5dB at the BER of 10 − 5 in a 2-hop network where 2 antennas and 4 antennas are placed on the relay and the terminal, respectively. This paper shows that 6 stream spatial multiplexing is made possible in the system with 2 antennas on the relay.