Research On Single-Channel Full-Duplex MAC Protocol

Full-duplex communication is one of the key techniques for the 5G and future wireless communication systems. Single-channel full-duplex communication, which means the station can receive and send information in one channel, can improve the link capacity and spectrum efficiency. Full-duplex communication can be realized with the development of self-interference cancellation(SIC) technology, which brings a great change to the existing WLAN. Since the traditional half-duplex MAC protocol cannot meet the needs of full-duplex communication, researches on full-duplex MAC protocol are significant to further improve the network capacity and spectrum efficiency.This dissertation focuses on the single-channel full-duplex MAC protocols. The single-channel full-duplex DCF(FD-DCF), full-duplex CSMA(FD-CSMA) and full duplex PCF(FD-PCF) protocols are proposed based on the distributed coordination function(DCF) and the point coordination function(PCF) of IEEE802.11 MAC layer. The specific content and innovation points are as follows:(1) As the traditional half-duplex DCF(HD-DCF) cannot be applied to full-duplex communication, a single-channel full-duplex DCF(FD-DCF) protocol is proposed. After the RTS/CTS frame are reasonable modificated, according to the different network scenarios and the full-duplex capability of stations, four transmission modes of the FD-DCF are given, including synchronous full-duplex, asynchronous full-duplex, conditional half-duplex and half-duplex modes. Link establishment processes of four different working modes are introduced, respectively. Combined with the improved Markov model, the collision probability, normalized saturation throughput and medium access delay of the FD-DCF are analyzed. The simulation results show that the performance of the FD-DCF is greatly improved, compared to that of the HD-DCF, especially for the conditions of longer frame length, less station number and lower data rate. Compared with the classical full-duplex protocol “ContraFlow”, the FD-DCF can be applied to full-duplex network, half-duplex network and hybrid duplex network by sacrificing the throughput and delay performance.(2) Considering the sensing delay problem of collision sensing for traditional CSMA mechanism and the nonideal physical layer carrier sensing, a full-duplex CSMA(FD-CSMA) protocol is proposed, where the full-duplex technique is adopted to carry on the uninterrupted carrier sense, and stop sending the data immediately when the collision occurs. The mechanism of carrier sensing and collision avoidance, and the transmission process for false alarm and missing detection are analyzed. Combined with the improved Markov model, the normalized saturation throughput and the medium access delay of the FD-CSMA protocol are studied. Simulation results show that the performance of the FD-CSMA is obviously improved, especially under the conditions of a large number of stations and long frame length.(3) Since the half-duplex PCF(HD-PCF) protocol cannot be applied to full-duplex communication and the polling strategy is inefficient, a high efficient single-channel full-duplex PCF protocol(FD-PCF) is proposed. Considering the full-duplex capability of staions and a FD-PL structure, the FD-PCF can be applied to the full-duplex and half-duplex network, and the channel resource is allocated by centralized polling strategy. The communication rules and frame transferring process of the FD-PCF are analyzed, and the medium access delay and normalized throughput are also discussed by using the M/G/1 vacation queue model. Simulation results show that the performance of the FD-PCF is significantly better than that of the traditional PCF, especially for the long frame length and high packet arrival rate.