Scalable Video Transmission In Software Defined Wireless Mesh Network

With the rapid development of wireless communication technologies and the in-creasing popularity of smart terminal devices,the demand for mobile streaming video services continues to increase.Since the bandwidth consumption of video traffic is large,which puts tremendous pressure on the wireless network,it needs to be further optimized for wireless video transmission.Wireless Mesh Network(WMN)is one of the key technologies for wireless access networks and has been widely used.Through the wireless multi-hop communication method among network nodes,WMN expands the coverage of its wireless communication,which is considered to be an effective so-lution to solve the "last mile" bottleneck problem.However,due to the distributed self-organization characteristics,WMN has a poor network resource allocation and low performance,and lacks optimization of specific services such as video transmission and support for quality of service(QoS).In order to optimize the transmission of video in WMN,a software-defined net-working(SDN)architecture is introduced to achieve centralized control.The SDN architecture separates the control plane of the network from the data plane,and the controller performs centralized control and management on the network,thereby real-izing real-time collection of network information and intranet control of data streams.Within the Software-Defined Wireless Mesh Network(SDWMN)architecture,this the-sis adopts scalable video coding(SVC)to realize the bitrate adaptation of video trans-mission,and designed a SVC video adaptive transmission strategy.The main work is summarized as follows:First,the SDN architecture is introduced into the WMN and the SDWMN architec-?ture is constructed.Then,a scalable video transmission system on this network archi-tecture is designed.In this system,the controller is responsible for managing the routing nodes and periodically collecting network status information.The management server is responsible for dynamically determining the number of video layers to be sent by the SVC video stream according to the network status,and notifying other modules.The media server sends the corresponding video stream according to the decision informa-tion.At the same time,the routing nodes on the video transmission path are configured with the flow table sent by the controller and transmit the video stream to the client.Secondly,the mathematical model of SVC video transmission process is estab-lished,and the video transmission problem is modeled as a video quality maximization problem under the constraint of congestion probability.In order to solve the problem,a video bitrate adaptive algorithm under the constraint of link congestion probability is proposed with the congestion probability estimated by using large deviation theory.By dynamically adjusting the number of SVC video's layers to be sent,the algorithm can improve video quality as much as possible while avoiding link congestion.Finally,in order to verify the performance of the proposed system and transmission strategy,comparative experiments were carried out on the simulation platform Mininet-WiFi,which was compared with the traditional wireless mesh network and other video transmission strategies.The experimental results show that the proposed system and transmission strategy can improve network performance,effectively avoid network con-gestion and improve video quality.