Wireless Video Delivery Strategy And Performance Optimization

In recent years,with the development of multimedia technology and the proliferation of video application market,video streaming has become the most part of the Internet traffice.According to the Cisco's report,video traffic will account for about 75%of the total transmission data over Internet at the end of 2020.As a very important network application,surveillance video is becoming more and more popular in social life,it porvides security service for people's housing,traffic,health,production,etc.At the same time,as wireless communication has the advantages of economical,practical,flexible and easy to use,various wireless comminication technologies and relevant Internet of Thing(IoT)technologies developed rapidly,the spectrum resource have became more and more crowded,thus researchers in different contries started to study how to make good use of TV white spaces'(TVWS)hundred Mhz bandwidth in VHF and UHF,and there are numerous achievements of this research.As the video's data amount is relatively large,video surveillance system need reduce the cost of video storage and transmission,the encoded data quantity can be decreased by developing high efficiency video coding algorithm,which considering the characteristics of surveillance video.With the development of network technology and the popularity of cloud system,the users expect to use wireless networks remote viewing the HD surveillance video with wide viewing angle,thus we need to study video delivery scheme which is more efficient and better reliability,can ensure the video quality and satisfy the users'demands.For using TVWS to transfer video in IoT environment,as the unlicensed users can utilize the open spectrums free but in face of fierce competition,the video transmission quality can't be guaranteed.Hence the concept of High priority channel has appeared,which can be leased in a short duration for video transmission.This lead to studing on the strategy problem of balancing video quality,expenditure and GOP transmission delay.This thesis will study on these three specific problem,and the main contributions of this paper is in three aspects as follows.1)We proposed a SSIM-based surveillance video coding scheme,which solved the video encoding optimization problem of the surveillance video of constant changing scene.As SSIM actually measures the structure difference between two images,and it can be used to search proper reference frame when encoding one frame for decreasing background redundancy.Firstly,statistical experiment is repeated to verify that higher compression ratio can be achieved by selecting reference frame which has larger SSIM value when frame encoding.Then based on this observation,we proposed reference frame selection algorithm which used to select proper reference frame in order to improve the coding efficiency.At the same time,reference frame cache is added in to the proposed video coding scheme.Simulation results show the proposed scheme obtains better encoding efficiency comparing with the existing coding standard,video coding data can be saved.Even for the ordinary video,the efficiency of our scheme also achieves at least as well as existing coding standard.2)We proposed a real-time suveillance video transmission scheme RSVTS,which realizes real-time video transmission over wireless networks with wide viewing angle and high-definition to meet the users' demands.RSVTS merges multiple surveillance videos together and implements wide viewing angle and high-definition video transmission,and video coding scheme aforementioned is adopted in RSVTS to decrease encoded video data.Both of the sender side and receiver side include the reference frame cache for increasing optional reference frames,and reference frame managing algorithm is proposed to update appropriate reference frame.At the same time,network status is also considered in our scheme.We evaluate RSVTS'performance by conducting emulation experiment platform,experiment results shows RSVTS outperforms conventional surveillance video transmission schemes in decreasing video data amount and improving video quality.3)We proposed a TVWS-based video transmission scheme TVDS in Internet of things environment,as high priority channels(HPC)which can be leased for data transmission is exist in TVWS network,there is a tradeoff between expenditure and delay when the video quality demand is confirmed.Thus various algorithms of video delivery scheduling strategy is proposed,and providing delay,expenditure and quality balanced video delivery strategy for the users.First we presented the video data and TVWS models based on exist study of TVWS manage architechture,and the optimization problems is formulated.Then we proposed an online expenditure minimization algorithm,an online delay minimization algorithm,an offline expenditure minimization algorithm,and an offline delay minimization algorithm.The experiment results show that TVDS can provide flexible and effective video delivery scheduling strategy,and delay,expenditure,quality equilibrium can be achieved.