A novel threshold-based quadrature signaling scheme for cooperative networks

Presented is a novel threshold-based quadrature signaling (TQS) scheme for cooperative networks. By assigning different components of the quadrature signaling to different cooperative users and letting each user node decide whether to relay information for the other in the assigned component based on a threshold or not, independently, the TQS scheme effectively integrated the advantages of both quadrature signaling and threshold techniques. The authors investigate the end-to-end bit error rate (BER) performance and obtain its closed-form expression. According to our theoretical analysis, the TQS scheme can enhance the diversity gain of a cooperative system and, meanwhile, reduce the complexity of its implementation to a great extent. In addition, the communication system, using TQS scheme, has the feature of easily switching between cooperative and non-cooperative patterns. Finally, the numerical and simulation results show that the scheme has excellent performance as expected.