Research On Optimization And Key Technologies For Wireless Multimedia Transmission

With the increasing demand for smart devices,multimedia content traffic generated from them is predicted to increase at 62% per year.By the end of 2020,the number of global devices connected to Internet is predicted to reach 212 billions,and 75% of the mobile traffic is supposed to be multimedia.It has been too difficult to provide reliable multimedia transmission by current wireless networks because of resource and calculation limitations.Thus,more efficient smart multimedia transmission techniques have to be researched.Main works of this paper are summarized as follows.Firstly,a novel quality-driven joint source-channel coding(JSCC)scheme with unequal error protection(UEP)technique is proposed to meet high quality-of-experience(QoE)demand of multimedia services.The JSCC approach jointly considers delivery latency,energy constraint,and error correction techniques to optimize multimedia delivery quality in a cross-layer manner.For any given bit budget,the JSCC model felicitously allocates bits between source coding and channel coding among media streams.Second,for each intra refreshing rate,the source-aware UEP scheme dynamically allocates channel coding bits among frames,achieving maximum overall QoE.Simulations demonstrate that significant improvement in multimedia quality and remarkable conservation in energy and time consumptions can be achieved.It provides a cross-layer bit allocation method for end-to-end multimedia transmission.Secondly,the user-centered mode selection problem is formulated by maximizing quality of service(QoS)with total energy consumption constrained.The frequency reuse mode of device-to-device(D2D)links(underlay or overlay)at lower layers,the video coding mode of video frames(I,P,or B)and multiple paths(cellular links and/or D2 D links with/without relays)at higher layers are jointly selected for multimedia transmission.Evaluation shows that the proposed unified power allocation and mode control scheme enhances perceived QoS with various energy constraint and different distances of paths.It also proves that coding all frames as I-frames,initializing relay transmission power as the maximum value,or selecting a single path for all video frames is not the best choice.The proposed joint power control and mode selection scheme boosts the mode selection research for D2 D network underlaying a cellular network with multi-antenna relays.Thirdly,a new low complexity distributed game theoretical source selection and power control scheme is proposed to enhance multimedia transmission quality with latency constraints.The proposed approach optimally selects the most beneficial source devices by analyzing interactions between base station's rewarding strategies(price)and devices' contributing behaviors(transmission power)using a Stackelberg game model.Optimal transmission power is adjusted for each selected source device in D2 D networks through deriving Stackelberg equilibrium,wherein the base station and the device both achieve maximum utilities.The proposed source selection scheme from economics view promotes the realization of D2 D communication.Simulations demonstrate that significant improvement in D2 D multimedia transmission quality can be obtained.Finally,a fundamentally new Stackerlberg pricing framework named Smart Media Pricing(SMP)is established among wireless service providers(WSPs),content providers(CPs),and end users(EUs).WSPs transmit media streamings provided by CPs to EUs with different transmission times' limitations(TTLs)based on payment from EUs,channel conditions,and media characteristics in terms of distortion reduction and importance.The optimal TTLs and prices are derived non-uniformly and intelligently among frames according to Stackerlberg game equilibria where the WSPs,the CPs and the EUs achieve the maximum utilities.Experimental comparison with uniform pricing based on equal TTLs or equal frame importance validates the effectiveness of the proposed approach.