A demonstration of a cooperative communication scheme using software defined radio

Cooperative communication is a promising approach to improve the reliability of a received signal at the physical layer. Cooperating nodes create a virtual MIMO system that provides spatial diversity even though the nodes have a single antenna. Therefore, tremendous improvements in system capacity and delay can be achieved. An implementation approach has been pursued in this demonstration to confirm the viability and efficacy of cooperation at the physical layer. The implemented cooperative physical layer scheme is called CoopPHY and is based on cooperative coding. In this technique, the source node transmits only a portion of its encoded data bits based on channel conditions among cooperating nodes. Helper nodes transmit the rest of the encoded bits. The destination node, finally, combines and decodes signals received via different channels and therefore increases the decoding reliability. In this demo, a Matlab video clip is streamed frame by frame from a source to destination node using sequentially the direct communication scheme, relaying via one helper, relaying via another helper and finally cooperative scheme. CoopPHY protocol delivers a smooth user experience, while the video playout over the direct scheme shows frequent distortions. In addition to this cooperative coomunication shows better quality than just relaying via any of the helpers.