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1、source-channel coding as an element of a QoS framework for 4G wireless multimediaOriginal Research ArticleComputer CommunicationsThe development of Beyond 3GB3Gor 4G networks and applications, with all-IP based ubiquitous and seamless service provisioning across heterogeneous infrastructures, presen
2、ts a number of challenges beyond existing capabilities conceived so far by the IETF for Mobile IP and by the ITU for Third Generation networks. Management, signaling and transport functions must evolve from different link layer technologies, uniformly and end-to-end, to the packet switched IP-networ
3、k layer. Global mobility throughout all network types requires capability for seamless handover between different administrative and technology domains, extending at the same time the present edge mobility concept to ad-hoc networks and to mobile networks. Having at least identified, if not solved,
4、these important problems, the technical key challenge for this B3G or 4G world remains to provide IP-based audio and video communications at the same or at least comparable carrier class and bandwidth efficiency as the corresponding circuit-switched subsystems of 3G and 2G. In the IETF, some element
5、s to achieve this goal have been identified and are under discussion: situated between link and IP layers, the Robust Header Compression (ROHC) framework addresses the problems of spectrum and bandwidth scarcity and of bit errors characterizing wireless links. The fact that, for some applications, e
6、rroneous packet payloads can be valuable and better to cope with than lost ones, has inspired the introduction of the UDP-lite transport protocol. Assuming ROHC, UDP-lite and an appropriate inter- or cross-layer signaling mechanism in action, this paper is going to elaborate and incorporate the join
7、t source and channel codingJSCCparadigm into a complete QoS framework for 4G mobile wireless multimedia communications.Article Outline1. Introduction2. QoS for multimedia in a 4G world: related work 2.1. The 3GPP QoS framework2.2. IETF considerations 2.2.1. Link layer considerations2.2.2. Header com
8、pression and UDP-lite2.2.3. Existing Internet QoS architectures3. Traditional transform coding: issues WRT wireless channels 3.1. Design principles so far3.2. Issues related to delivery over wireless networks4. Erasure resilient source coding 4.1. Quantized frame expansions: principles and analogy w
9、ith codes on the real and complex fields 4.1.1. Elements on frames4.1.2. Analogy with codes on the real and complex fields4.1.3. Quantized frames or joint source-channel codes4.1.4. Quantized frames decoding and erasure recovery4.1.5. Examples4.2. Exploiting channel diversity or multiple description
10、 coding 4.2.1. Multiple description quantization4.2.2. Multiple description coding based on polyphase transforms5. Error resilient source coding 5.1. Soft-decision decoding of VLCs5.2. Error-resilient source codes5.3. Bitstream structuring for robust transmission5.4. Error correction based on quanti
11、zed frame expansions6. Steps towards a complete joint source-channel coding system for 4G wireless multimedia: example of video 6.1. Architecture with end-to-end and cross-layer information exchange6.2. End-to-end congestion control with loss differentiation6.3. Fine grain scalable representation fo
12、r flexible rate and congestion control6.4. Support of backward-compatible erasure-resilient capability in the FGS coding system6.5. Error-resilience support in the FGS coding system and signaling implications7. ConclusionReferencescontrol protocol for voice and data integration in receiver-oriented
13、DS-CDMA PCNsOriginal Research ArticleInformation and Software TechnologyPrimarily used in military communications in the past, code division multiple access (CDMA) is recently found to be attractive for personal communications as well. As a large number of mobile hosts are supported within a cell an
14、d a wide range of services are provided, one of the most important issues in a CDMA personal communication network is how to control the uplink access to the shared wireless spectrum. In this paper, we address this issue in a realistic situation where the receiver-oriented transmission protocol is e
15、mployed and the packet loss due to multiple access interference (MAI) cannot be ignored. A medium access control protocol for voice and data integration is proposed. It solves the problems of code assignment and MAI control at the same time. A Markov chain model is used to analyze the protocol and t
16、he analytical results are shown to be very close to simulations. Based on the modeling, the effectiveness of the protocols MAI control is demonstrated and some system design issues are investigated.Article Outline1. Introduction2. Preliminary 2.1. Overview of code division multiple access2.2. Previous research3. A protocol for voice and data integration 3.1. Problems and their sol
