Research On Full-duplex MAC Algorithm Based On IEEE 802.11ax

In recent years,due to the rapid development of wireless terminal technology,a large number of new devices with high intelligence and high performance have been introduced into the market,leading to the explosive growth of Internet communication services.Because of its low cost,high throughput and flexible deployment characteristics,Wireless local area network(WLAN)has been widely used and become the main Internet access method.With the increasing of mobile data traffic and mobile Internet devices,WLAN communication technology is constantly changing.As the next-generation WLAN standard,the IEEE 802.11 ax protocol introduces plenty of new physical(PHY)layer and medium access control(MAC)layer technologies to solve communication problems in dense network scenarios.However,owing to the increasingly tight wireless spectrum resources and the constraints of the half-duplex communication mode,the existing WLAN standard technology has a performance bottleneck.In band full duplex(IBFD)wireless communication technology can support simultaneous communication on the same frequency,and theoretically will increase the spectral efficiency twice,making the combination of it and WLAN technology gradually become the wireless communication field research hotspots.At present,with the development of physical layer selfinterference cancellation technology,it has become feasible to introduce IBFD technology into the PHY layer of IEEE 802.11 ax.At the same time,it is necessary to redesign the efficient MAC layer protocol to adapt to the technical changes of the PHY layer.In response to this problem,this article focuses on the full-duplex MAC protocol in IEEE 802.11 ax,including full-duplex multi-user access,full-duplex multi-channel resource allocation,frame design,etc.The specific work is as follows:Firstly,a channel access control mechanism based on full-duplex OFDMA proposed in this thesis.The MAC mechanism can implement multi-user full-duplex channel access based on the existing IEEE 802.11 ax standard.Meanwhile,in order to solve the asymmetric traffic scenarios in the full-duplex network and the inter-STA interference caused by the three-node full-duplex communication mode,a channel resource allocation algorithm based on the global interference graph is proposed.In addition,so as to be able to implement this protocol in a real WLAN environment,this article has carried out a detailed design for the control frames needed in each MAC phase.Secondly,in view of the insufficient performance advantage of the above mechanism in the low-density station(STA)environment,a full-duplex OFDMA channel resource allocation algorithm based on a combined optimization strategy is proposed.This algorithm requires the access point(AP)to assign downlink STAs to each subchannel first according to the downlink buffer order,thereby increasing downlink throughput to a certain extent and improving STA access fairness.At the same time,in order not to lose the uplink throughput and better apply to asymmetric network scenarios,the algorithm uses the buffer queue information of the uplink STAs to build an arc flow graph,and searches for the optimal uplink STA scheduling according to the minimum interference objective function.Finally,a theoretical model established for the above two algorithms,so as to analyze the network throughput,system delay and time fairness.Meanwhile,the performance of two algorithms is verified through the MATLAB simulation platform.