Research On OFDMA Based QoS Oriented Multi-user Multiple Access Protocol For The Next Generation WLAN

Due to the rapid development of mobile Internet and the wide application of intelligent terminals,the amount of data carried by wireless networks has increased dramatically,and the wireless services become increasingly diverse.Wireless Local Area Network(WLAN)has become the main carrier of wireless network services.In order to cope with the rapid growth of wireless demands,Academia,industry and the 802.11 Standardization Organization of the Institute of Electrical and Electronics Engineers(IEEE)are paying more and more attention to the key technology research and standardization process of the next generation WLAN.The next generation WLAN standard revision,IEEE 802.11 ax,which is will be officially released in late 2019.It takes the high-dense deployment scenario as the target scenario of the next generation WLAN.The existing media access control(MAC)technology of WLAN has the shortcomings of dramatic reduction of MAC efficiency in high-dense deployment scenarios,which seriously restricts the performance of WLAN system.Therefore,the next generation WLAN introduces multi-user multiple access technology with Orthogonal Frequency Division Multiple Access(OFDMA)as the key technology,in order to significantly improve the efficiency of MAC.Improving quality of service(Qo S)is one of the key technical goals of future wireless networks and the next generation WLAN.However,after some research on the multi-user multiple access protocol itself,how to design an efficient multi-user multiple access protocol with good backward compatibility to ensure the quality of service for different types of services,especially high priority services,is an urgent technical issue to be studied.Typical requirements include how to guarantee the Qo S of the increasingly rich latency-sensitive services,how to guarantee the high-priority services and inter-service fairness in the high-density deployment scenario,and how to guarantee the Qo S of the ultra-large data volume and layered services.These problems are closely concerned by current academic circles and standards organizations.Unfortunately,there are few related studies in this field.To solve these problems,this dissertation studies the next generation WLAN multi-user multiple access protocol based on OFDMA for Qo S.The innovations of this dissertation are summarized as follows:1.Aiming at the problem of Qo S guarantee for latency-sensitive services,an OFDMA based latency-sensitive multi-user multiple access protocol,which is called LS-OFDMA for short,is designed and the corresponding priority scheduling algorithm for Qo S is proposed.The basic idea of LS-OFDMA is to take the latency-sensitive characteristics of services as the key factor of protocol process and algorithm optimization,and take into account the bandwidth requirements.The protocol has good backward compatibility.Next,an integrated simulation platform of link-system level for IEEE 802.11 ax is designed and built.This dissertation verifies the performance of the standardized multi-user multiple access protocol of IEEE 802.11 ax,which proves its performance advantages.Then,LS-OFDMA protocol and scheduling algorithm are simulated based on the integrated simulation platform.The simulation results show that the effective throughput of LS-OFDMA system is 56.8% and58.8% higher than that of sequential scheduling algorithm and proportional fair scheduling algorithm,respectively.2.To solve the problem of how to guarantee high-priority service quality of service and fairness between services in high-dense deployment scenarios,a multi-user multiple access protocol based on double random access is designed,which is called DRA-OFDMA for short.The basic idea of DRA-OFDMA protocol is to introduce OFDMA based double random access procedures: the first random access ensures fairness because the access does not differentiate between service types;the second random access only allows high-priority users who fail in the first access to perform the second random access on the remaining available resources after the first access,thus increasing the high-priority services.The probability of success guarantees the quality of service.The protocol has good backward compatibility.Next,the DRA-OFDMA protocol is modeled by discrete two-dimensional Makov,and the network throughput is analyzed based on the model theory.Furthermore,the performance of DRA-OFDMA protocol is simulated based on integrated simulation platform.On the one hand,the simulation results verify the correctness of the mathematical model and theoretical analysis.On the other hand,it shows that the designed DRA-OFDMA protocol improves the throughput of high-priority services by 22% and 89% respectively compared with RA-OFDMA protocol and O-MAX protocol,and at the same time guarantees the commonality between high-priority services and low-priority services.3.Aiming at the problem of guaranteeing the quality of service of huge data and layered services(such as high-definition video),a multi-user multiple access protocol supporting layered services is designed,which is called LT-OFDMA for short.The basic idea of LT-OFDMA protocol includes two aspects.On the one hand,introduce the channel bonding technology of WLAN to obtain more bandwidth or introduce the channel resources to ensure the transmission requirements of large data traffic.On the other hand,hybrid random access based on layered services is introduced.Specifically,for the first successful layered service users,the basic layer needs are guaranteed,and hybrid random access is allowed on the remaining RUs and enhanced layer data are transmitted to achieve better quality of service.For layered service users whose first random access fails,they are allowed to perform hybrid random access on the remaining resources and send data from both the base layer and the enhancement layer to obtain better quality of service directly.The protocol also has good backward compatibility.Furthermore,LT-OFDMA protocol is simulated based on integrated simulation platform.The simulation results show that the throughput of layered service user by using LT-OFDMA protocol is increased by 154% compared with the existing literature.