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1、Enhancing Mobile Video Service Capabilities over Next-Generation WiMAXIEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE C802.16-10/0007 Date Submitted: 2010-01-10 Source: Ozgur Oyman, Jeffrey Foerster E-mail: ozgur.oyman, Intel Corporation Venue: San Diego, CA, USA Base Co

2、ntribution: None Purpose: For discussion in the Project Planning Adhoc Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis

3、for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the

4、 creation of an IEEE Standards publication; to copyright in the IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contrib

5、utor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures:and . Further information is located at and .,Mobile Video Services,Important key trends Mobile traffic is growing sig

6、nificantly, will be dominated by video and data Mobile devices are getting more powerfulnew usages possible Mobile graphics is getting better Continuum of screen sizes exist BUT, Wireless capacity still limited Still long ways from true IPTV/video-on-demand to mobile devices Traffic trends and new u

7、sages will continue to stress capacity further,Figure 1. Cisco Forecasts 2 Exabytes per Month of Mobile Data Traffic in 2013*,Figure 2. Laptops and Mobile Broadband Handsets Drive Traffic Growth*,*Source: Cisco Visual Networking Index, Oct. 2009,*Source: Cisco Visual Networking Index, Oct. 2009,Mobi

8、le Content Delivery Methods,Internet (Hulu, Joost,Netflix, Blockbuster),Broadcast Networks,Home (Slingbox),IPTV, cable, telecom carrier,WiFi Hotspot,Broadband wireless (e.g., WiMAX),Broadcast (Terrestrial, Sat.),Multiple Devices,Mobile content delivery methods: Streaming: unicast, broadcast Download

9、: kiosk, STB, over-the-air New usage models Video conferencing, video share Video twitter, video blogging Live video broadcasting, video upload,Kiosk,Key criteria: Quality Latency Throughput Capacity Scalability Cost,Multiple Networks,Multiple Content Sources,Car,Outline,This talk addresses the foll

10、owing two key challenges for enhancing mobile video service capabilities over next-generation WiMAX:Capacity: Can WiMAX support high-bandwidth video applications? How many video users can WiMAX serve in the presence of voice and data traffic? QoS: How should next-generation WiMAX standard better man

11、age QoS for mobile video services?Another key mobile video challenge (not addressed in this talk): Adaptability and Scalability: How can the network adapt and scale to support time-varying conditions and multiple device classes?,1- Video Capacity over WiMAX,Assess the viability of mobile video servi

12、ces over current (16m) and next-generation (16x) WiMAX networksEvaluate the video service capacity of current and future WiMAX-based networks with voice and data traffic presentIn the capacity analysis, we consider the following services over WiMAX: Unicast video services Multicast/broadcast service

13、s (MBS)Our key assumptions for this analysis are as follows: 16x networks will support higher channel bandwidths in the order of 40-80 MHz. 16x networks will provide 2X higher spectral efficiency than 16m. Consider the same amount of service overheads in 16m and 16x.,MBS Video Capacity Evaluation Me

14、thodology,The number of MBS video channels for WiMAX is computed based on the following formula:,Number of usable OFDMA subcarriers for data transmission,Number of DL OFDMA symbols per frame allocated for MBS,Percentage of overhead for MBS,MBS spectral efficiency in bps/Hz,Data rate in bps for the M

15、BS video channel,Frame duration in seconds,MBS Video Capacity,Maximum of 50% of total available DL OFDMA resources allowed for streaming video to allow for concurrent voice and data services, DL:UL ratio = 2:1.,Unicast Video Capacity Evaluation Methodology,The number of unicast users per sector for

16、DL video transmission is computed based on the following formula:,Number of usable OFDMA subcarriers for data transmission,Number of DL OFDMA symbols per frame for unicast video,Percentage of overhead for DL unicast video,DL unicast video spectral efficiency in bps/Hz/sector for n-th scheduled user

17、among N users in the sector (n=1,N),Data rate in bps for the unicast video service,Frame duration in seconds,WiMAX Unicast Coverage and Capacity,* Maximum of 50% of total available DL OFDMA resources allowed for streaming video to allow for concurrent voice and data services, DL:UL ratio = 2:1. * No

18、te: Typical PER for video should be 1%, so coverage and throughputs are optimistic.,WiMAX capacity for DL Unicast video streaming at different rates (average # of unicast video users per sector which can be serviced),WiMAX coverage for DL Unicast video streaming at different rates,Observations,Curre

19、nt network capacity limits number of simultaneous video streams.With more bandwidth and higher spectral efficiency, next-generation WiMAX can provide much higher capacity for serving more video users and supporting larger number of video streams.,2- Optimizing Video Quality,Quality-aware networking

20、for video communications to optimize user experience ensure end-to-end robustness of content deliveryQuality degradation may be caused by high distortion, limited bandwidth, excessive delay, power constraints, complexity & cost limitations Application-aware optimization needed: In the network to ens

21、ure end-to-end robustness of video content delivery Ex: transmission reliability based on “perceptual importance” of video bits Ex: app QoS-driven cross-layer design approaches for resource allocation and management leads to new notions of efficiency and fairness At the client to ensure user experie

22、nce driven optimization (PHY-APP cross layer design) Ex: application rate, codec adaptation based on predicted link & network conditions, joint source-channel coding optimizations,Application Layer,Client,IP,TCP,UDP,Cross-LayerOptimization,Distortion-Aware PHY/MAC Design for Enhanced Multimedia Deli

23、very,For video communication, users perceived quality for multimedia content is dictated by end-to-end distortion.Goal: PHY/MAC layer design to minimize end-to-end distortion.Our analysis suggests that this design goal significantly modifies how PHY/MAC components work compared to current system des

24、igns.Distortion-awareness requires new design methods than more standard optimizations, such as maximizing spectral efficiency or throughput. Relevant topics for distortion-aware processing: Cross-layer design (PHY/MAC/NET/APP) Joint source-channel coding,Distortion-Aware PHY/MAC Design for Enhanced

25、 Multimedia Delivery,Joint Source-Channel Coding (JSCC),Separate source-channel coding: Source coding independent of channel structure & channel coding independent of source structureJoint source-channel coding (JSCC) aims to jointly optimize source compression and channel coding.JSCC goal: Minimize

26、 end-to-end distortion by simultaneously accounting for the impact of both source quantization errors and channel-induced errors.,Distortion-Aware Link Adaptation,Let R be channel coding rate associated with a given MCS in bps/Hz.It is assumed that the distortion-rate function D(R) for the multimedi

27、a source/codec is made available at the radio level for PHY/MAC optimizations.Classical system design approach aims to maximize throughput or goodput (possibly subject to a target PER):Proposed distortion-aware MCS selection criterionInterested in peak SNR (PSNR) defined as (determines users perceiv

28、ed quality of video):,Peak SNR Performance Comparison,Observations,Distortion-aware link adaptation ensures robust user quality of experience (QoE): Enables reduced PSNR variability and graceful PSNR increase/decrease with changing link conditions High PSNR fluctuation and variable QoE with the thro

29、ughput-maximizing approach. Operate at lower PER, reliability is relatively more important than rate. Significant PSNR penalty from throughput-maximizing link adaptation over distortion-aware link adaptation,Distortion-awareness requires new PHY/MAC design methods than more standard optimizations, s

30、uch as maximizing spectral efficiency or throughput.,Conclusions and Recommendations,Dominance of video content over wireless networks in future creates unique opportunity to optimize WiMAX for video applications.Initial results show significant gains possible with distortion-aware processing and cr

31、oss-layer optimizations.Recommendations for Next Generation WiMAX:Optimizing video capacity and QoS should be a key focus area toward developing new PHY/MAC specifications.New system requirements should be established for mobile video services (e.g., minimum number of video users, etc.)New performance evaluation methodologies and target requirements are needed to account for various video quality metrics (e.g., distortion, PSNR, etc.)Video-enhancing techniques such as JSCC and distortion aware processing, should be adopted to anticipate future growth of video services.,