Research On Orthogonal Frequency Division Multiple Access Technology Based On Spatial Cluster Group In Next Generation WLAN

Wireless local area network(WLAN),as one of the most important ways of carrying wireless network traffic,has been widely concerned and developed rapidly.In recent years,the rapid growth of people’s demand for wireless data and the rapid development of the Internet of things make the high dense deployment scenarios become an important trend of wireless networks in the future,which brings the difficult technical challenges for wireless networks.Therefore,the next generation WLAN standard,IEEE 802.11 ax,takes the orthogonal frequency division multiple access(OFDMA)technology as the key technology.However,the existing research of OFDMA based multiple access technology in the next generation WLAN has the problems of spatial interference extensions and mutual inhibition of time domain adjacent node access,which restrain the efficiency of multiple access and area throughput of WLAN.To solve the problems,this thesis proposes the spatial clustering group based OFDMA(SCG-OFDMA)in the next generation WLAN.The core idea of SCG-OFDMA is that multiple nodes close to each other can access and share the OFDMA concurrent transmission opportunities through OFDMA in a coordinated manner at the same time.To sum up,this thesis studies OFDMA technology based on spatial clustering group in next generation WLAN,and summarizes the innovations as follows:1.Aiming at the problems of interference extensions in spatial domain and mutual inhibition of access between adjacent nodes in time domain existing in OFDMA multiple access technology in next generation WLAN,an SCG-OFDMA protocol based on single user(SU)competitive channel is proposed,which is called SU-SCG-OFDMA for short.SU-SCG-OFDMA can effectively improve the throughput and area throughput.The core idea of SU-SCG-OFDMA is that each node competes for the channel independently.When any node competes for the right to use the channel,it will automatically become the cluster head of the spatial clustering group,and trigger the nodes with the same data transmission needs around it to form the spatial clustering group,sharing the access and transmission opportunities of OFDMA.The designed protocol flow and frame structure have good compatibility with IEEE 802.11.Furthermore,the existence of optimal access radius of spatial clustering group is proved by theoretical analysis,and the mathematical expressions of throughput and area throughput of SU-SCG-OFDMA are established and derived.The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance.The results show that SU-SCG-OFDMA has obvious advantages in throughput and area throughput compared with the existing OMAX protocol,IEEE 802.11 ax multi-user access protocol and IEEE 802.11 ax single user access protocol.2.In order to solve the problem of increasing conflict and low access efficiency of single user competitive channel in high dense deployment scenarios,an SCG-OFDMA protocol and its enhancement protocol based on multi-user parallel competitive channel,MU-SCG-OFDMA and e MU-SCG-OFDMA for short,are proposed.MU-SCG-OFDMA and e MU-SCG-OFDMA can effectively reduce channel access conflict and improve the OFDMA access efficiency of cluster member nodes.On the one hand,multiple users are allowed to compete for channels at the resource unit(RU)level in parallel,so as to significantly reduce the channel access conflict.On the other hand,the cluster member nodes can adopt the hybrid access method of scheduling access and random access in the data transmission stage,so as to improve the OFDMA access efficiency of the cluster member nodes.On this basis,e MU-SCG-OFDMA is enhanced in terms of spatial clustering group formation protocol and support for traffic unsaturated characteristics.The designed protocol flow and frame structure have good compatibility with IEEE 802.11.Furthermore,the optimal access radius of the traffic in the unsaturated state is analyzed,which makes the relevant theoretical analysis more general,and the expressions of throughput and area throughput of the proposed protocol are modeled and derived.The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance.The results show that MU-SCG-OFDMA and e MU-SCG-OFDMA have obvious advantages in throughput and area throughput compared with OMAX protocol and IEEE 802.11 ax.3.In order to make the idea of spatial clustering group proposed and studied in this thesis better adapt to the multi bands access ability and multi basic service sets(BSSs)cooperative access ability of IEEE 802.11 be standard which just started in 2019,an SCG-OFDMA protocol based on multi BSSs association,referred to as MA-SCG-OFDMA,is proposed,which can further expand the idea of SCG-OFDMA to adapt to the new IEEE 802.be standard effectively.The core idea of MA-SCG-OFDMA is to allow nodes located in overlapping coverage areas of multiple BSSs to associate multiple BSSs,and adopt the multiple BSSs parallel backoff algorithm.When nodes complete backoff in any BSS’s working channel,the nodes access the channel immediately and use SCG-OFDMA to perform access and transmission.The protocol flow and frame structure have good compatibility with IEEE802.11.The results show that MA-SCG-OFDMA and IEEE 802.11 be can significantly improve the throughput and area throughput on the basis of making full use of multi band access capability and multi BSSs cooperative access capability.The simulation results show that MA-SCG-OFDMA is suitable for IEEE 802.11 be,and the throughput and area throughput can be significantly improved on the basis of making full use of multi band access capability and multi BSSs cooperative access capability.