Research On QoS-oriented Channel Access Algorithms In IEEE 802.11ax

In recent years,Wireless Local Area Network(WLAN)has been widely used due to its high rate,flexible deployment and low cost.With the continuous increase of intelligent mobile terminals,the intensive deployment of WLANs will inevitably become a trend,and people also put forward higher requirements on the performance of WLANs.Although the recent IEEE 802.11 ax draft is a solution for high-density network deployment,there are still some shortcomings.First of all,in the high-density network environment,there will be more stations(STAs)of different access categories(AC),and the users' requirements for Quality of Service(QoS)will also continue to increase.However,However,IEEE 802.11 ax does not provide a good QoS guarantee mechanism for the uplink multi-user access process.Secondly,IEEE 802.11 ax still uses the binary exponential backoff method in the process of channel access,and does not allocate channel resources,which will lead to the decrease of resource utilization in dense scenarios.Therefore,in dense networks,it is critical to ensure users' QoS and improve resources utilization.The main work of this thesis is as follows:Firstly,to ensuring user QoS and improving the resource utilization of the uplink transmission process,an adaptive random access algorithm based on QoS perception is proposed.In this thesis,the contention process in IEEE 802.11 ax is divided into multiple contention rounds,and the simulated annealing algorithm is used to optimize the contention window(CW)during several contention rounds.The optimized CW value is broadcast to each STA through access point(AP).At the same time,in this process,the AP allocates uplink resources according to the data packet size of the STA,so that the resource utilization rate of the data transmission process is improved.for ensuring the QoS of users,the algorithm uses a redundant competition mechanism to allow high-priority STAs to have more opportunities to participate in channel competition during the multiple rounds competition process.Secondly,in view of the problem that the above QoS guarantee mechanism does not clearly distinguish different access categories,an uplink resource allocation algorithm based on QoS awareness is proposed in this thesis.The algorithm first assigns different transmission opportunities(TXOP)to different STAs according to the current network environment and access categories.Then,the AP executes an uplink resource allocation strategy based on the TXOP allocated to each STA.This strategy uses the idea of multi-machine scheduling to find a better solution for the allocation of resources among STAs,so as to make the resource utilization higher.Finally,the above algorithms are simulated by MATLAB simulation software.The simulation results show that the algorithm proposed in this thesis can guarantee the user's QoS effectively.At the same time,the algorithm can also effectively improve system throughput and reduce channel access delay.