Research On QoS/QoE-Aware Multiple Access Technology In The Next Generation WLAN

With the rapid popularization of smart device and the rapid development of network services,the demands of accessing to the Internet with high speed at anytime,anywhere becomes more and more stronger.The Wireless Local Area Network(WLAN)based on the IEEE 802.11 standard is an important way of wireless accessing due to its convenient deployment,low cost,fast speed and so on.At present,the standard of the next generation WLAN,i.e.,IEEE 802.11 ax has entered the stage of key technology research and proposal discussion,and is expected to be officially released in 2019.Providing better Quality of Service(QoS)and Quality of Experience(QoE)support in dense user scenarios is one of the key goals of the IEEE 802.11 ax.The traffic in the WLAN can be divided into uplink(from the user to the access point)and downlink(from the access point to the user)according to their direction.Users need to access to the network before transmitting their uplink traffic,therefore the QoS of uplink traffic is seriously affected by the access efficiency.The downlink traffic is managed by AP,and the video service occupies an important proportion of the downlink traffic,in addition to QoS support,users expect QoE guarantee when they watch video service.In this thesis,we mainly focus on the uplink traffic QoS and downlink traffic QoE aware multiple access technology in the next generation WLAN.The work and contributions in the dissertation can be summarized as follows:1.A QoS-Aware Orthogonal Frequency Division Multiple Access(OFDMA)Multiple Access Control(MAC)protocol is proposed.Aiming at the transmission delay of uplink video traffic cannot be guaranteed reliably,a redundant access mechanism is proposed to improve the access success rate of video traffic users,and the reliable transmission of video traffic is guaranteed by the priority based resource allocation algorithm and the frame aggregation mechanisms.The simulation results show that the maximum transmission delay of the video frame can be kept to be less than the range of the video frame generation period(0.033s),when the number of access subchannels is 4.2.A QoS-Aware channel bonding MAC protocol is proposed.Considering that the channel bonding MAC protocol of the IEEE 802.11 ac has low access efficiency problem and has not considered the QoS guarantee of video traffic,we adopt the primary/secondary channel multiple subchannels access mechanism to improve the access efficiency,and use the QoS based resource allocation algorithm to guarantee the QoS of the uplink video traffic.The simulation results show that the proposed protocol outperforms the channel bonding MAC protocol of the IEEE 802.11 ac in terms of QoS guarantee of uplink video traffic.3.A QoE-Aware bi-level resource allocation algorithm is proposed.Aiming at the problem of the dynamic change of the play buffer that caused by the uplink and downlink resource sharing scheme and variable bit rate of video traffic,based on the analysis model of the playback fluency of HTTP video streaming,AP calculates the download rate requirements of video traffic users according to their play buffer states,and then perform the first level resource allocation(between uplink and downlink)by adjusting the minimum contention windows and perform the second level resource allocation(among downlink video traffic users)with a token based scheduling algorithm.The simulation results show that the proposed algorithm can effectively avoid the stalling events in the playback process and guarantee the fairness among video traffic users.4.A QoE-Aware admission control and resource allocation algorithm is also studied.Since the QoE of video traffic cannot be guaranteed when resource requirements of users exceed the maximum throughput of the network,the playback fluency expectation of video traffic users and the throughput expectation of background traffic users are unified,then AP manages the access requirements of new users according to the admission control theorem and reallocates resources among the users when the number of users changes.The simulation results show that the algorithm can guarantee the playback fluency expectation of video traffic users and the throughput expectation of background traffic users at the same time.