Research On MAC Enhanced Technology Of Low Latency And High Reliability For WLAN

With the development of emerging technologies such as real-time cloud computing and telemedicine,low-latency and high-reliability communication scenarios have become the research hotspots of next-generation mobile communication networks.Wireless LANs have been widely used in people's daily work and life due to their advantages such as license-free,high-speed and flexible deployment.The main development of the WLAN standard is to increase the lingk rate,and its delay and reliability metrics will no longer meet the need of low latency and high reliability applications.Therefore,this paper studies the delay and reliability metrics of existing MAC enhancement technology based on 802.11 standard,and proposes a wireless LAN MAC enhancement technology suitable for low latency and high reliability scenarios,which has strong practical value and significance.The specific research contents and innovations of this thesis are as follows:First of all,this paper introduces the existing MAC protocol enhancement technology such as EDCA and HCCA mechanism,and analyzes theirs limitations to meet the parameterized Qo S.The performance of the EDCA mechanism is severely affected by the network load.When the number of certain types of AC users increases,the system delay performance deteriorates sharply.The HCCA is inefficient in dense scenarios and does not adapt to the user's frequent joining and leaving.The uplink random access process of the latest 802.11 ax standard and the DMMAC protocol in the Internet of Vehicles are studied as well,and the advantages and disadvantages of the MAC protocol under CSMA/CA and TDMA mechanisms are summarized.The OFDMA mechanism increases the success rate of multi-user access and makes the channel resource allocation more flexible and efficient.The DMMAC protocol combines the advantages of CSMA/CA and TDMA,but the problem is allocation and recovery of time slots based on the TDMA mechanism and the dynamic change of services and the assigned time slots are not always suitable.Therefore,in order to guarantee the delay and reliability indicators of time-sensitive services,the scheme adopts a polling-based enhancement mechanism by AP and a time-sensitive service priority scheduling mechanism to implement low-latency and reliable transmission through time slot scheduling.The specific innovations are as follows: The scheme divides the transmission resources into fixed-length periods,and accelerates the transmission of time-sensitive services by enhanced polling mechanism.The periodic transmission scheduling ensures the upper bound of the transmission delay;the user adpot the OFDMA+TDMA mechanism to achieve uplink random access,which increases user access efficiency in dense scenarios through multi-dimensional orthogonality;By classifying users according to service type,and the services are classified according to the metrics such as delay and reliability.The access window and the MCS selection policy are used to implement the hierarchical scheduling of time-sensitive services to meet the requirements of delay and reliability.Secondly,the mathematical modeling and theoretical analysis of the proposed low-latency and high-reliability wireless LAN MAC enhancement technology are carried out.The two-dimensional Markov chain model is used to model the enhanced random access process.The throughput,delay and stability indicators of the enhanced MAC protocol are established.The impact of user density,time-sensitive service proportion and protocol parameters on system performance are analyzed.The correctness of the mathematical model is verified by simulation,and the optimal performance parameter set of the system under saturated traffic load is obtained,which provides theoretical guidance for the implementation of MAC enhancement technology.Finally,the prototype system is built to verify the advantages of low latency and high reliability wireless LAN MAC enhancement technology.By designing the prototype based on Zynq architecture,the system architecture and core component design of the platform are given.The platform test was carried out in the laboratory environment,and the throughput and delay jitter of the platform were measured by Jperf network performance test tool,which verified the effectiveness of the enhanced technology and the feasibility of the platform solution.