mSCTP协议异构网络切换性能评估

在RFC 5061中,提出了一种对SCTP协议的扩展,采用地址动态重配置的方法,解决了现在网络设备IP地址不断变化的问题。RFC 5061的推出促进了SCTP协议在移动网络无缝漫游解决方案中的应用。在本文中,测试了SCTP和mSCTP协议的切换时延,验证了mSCTP在无缝切换中应用的可行性。切换的场景包括移动终端的慢速移动和快速移动两种情况。     

基于mSCTP的传输层移性研究

SCTP进行动态地址重配置扩展后被称作移动SCTP,可以在传输层对因特网移动性进行支持,进行端到端的移动性管理,并且不需要网络路由器的支持。本文讨论了分别在网络层和传输层实现因特网移动性的区别,分析了利用mSCTP实现平滑的移动切换的基本原理。为了实现对移动节点的定位,mSCTP需要和某种位置管理机制进行结合,这种机制既可以是移动IP,也可以是SIP。     

基于SCTP和移动IP的GEO天基网络移动性管理

相比基于低轨(LEO)卫星的天基网络,基于静止轨道(GEO)卫星的天基网络具有空间节点数量少、拓扑结构简单和系统建设成本低的优点。围绕用户终端在GEO天基网络中的移动性管理问题,利用移动IP架构的位置管理功能定位并追踪移动用户终端的网络位置,基于流控制传输协议(SCTP)的多地址归属特性保证移动切换过程中数据传输连接的连续性,提出了一种融合SCTP协议和移动IP架构的GEO天基网络移动性管理方案,具有良好的网络安全特性。测试结果表明,该方案既消除了移动IP架构固有的"三角路由"缺陷,同时具有较高的切换平滑性,是解决GEO天基网络移动性管理问题的有效方案。     

移动流媒体并行多路传输机制研究

随着我国移动终端的多样化以及人们对网络需求的不断增长,我国移动网络数据的传输数量在近5年增长迅速。然而人们利用移动终端进行网络传输时,通常会受到网络带宽、网络拥塞、网络时延等因素的影响。传统的传输控制协议(Transmission Control Protocol, TCP)与用户数据报协议(User Datagram Protocol, UDP)使用单条路径进行网络传输,已不能很好地满足人们对高速率、实时播放、大吞吐量等网络传输的需求。为了解决这一问题,文章提出一种移动流媒体并行多路传输机制,即多路径传输协议(Multipath Transmission Control Protocol, MPTCP)。该协议可充分发挥多路径传输特性,一方面优化了网络传输的性能,另一方面提高了用户的体验感。     

基于RealSystem的移动流媒体平台的实现

讲述了流媒体技术遵循的协议，移动流媒体的编码要求，移动流媒体的基本业务，提出了基于RealSystem的移动流媒体平台的实现方案及系统功能特点。     

基于丢包率统计的无线流媒体码率动态适配技术的研究

随着移动通信技术的不断发展,流媒体视频在无线环境下的应用得到普及。然而,移动网络环境所存在的不稳定性可能导致误码率高以及阻塞丢失严重的情况,从而严重影响用户的观看体验。因此,如何在现有移动网络环境发生频繁切换或网络较不稳定的情况下,仍使用户获得较好的流媒体视频播放体验,成了迫切需要解决的课题。本文研究提出了一种基于丢包率统计的无线环境下流媒体码率动态适配的方法,能够根据网络环境条件为用户重新选择适合用户的播放体验的视频码率,从而保证视频的传输质量和流畅度,优化用户的视频体验。     

移动流媒体业务技术概述

本文从技术层面简要介绍了移动流媒体业务的特点、分类、系统结构、业务功能以及移动流媒体所使用的传输协议等方面内容。     

移动流媒体业务架构的分析

本文介绍了移动流媒体技术的基本特征，阐述了流媒体的相关技术，包括传输流程、视频编码、传输协议等，并着重对移动流媒体系统架构进行分析，提出一种通用的移动流媒体三层分布式业务架构。     

移动视频解决方案

未来几年内移动流媒体视频业务将会有很大发展，移动流媒体业务的用户数将会不断增加，预计到2007年初，移动流媒体视频用户在流媒体总用户中将占20％以上，约为7300万用户。     

SCTP在NGN中的应用

本文研究了流控制传输协议（SCTP）作为一种新兴的传输层协议，在下一代网络（NGN）中的应用。重点分析了SCTP在移动Internet访问、无线异构网络的切换以及无线资源分配中相对于传统协议及方案的优势。     

A Smooth Handover Scheme for Fast-Moving Users in Mobile IPv6 Networks

As the rapid development of wireless technologies and increasing communication need of people in ubiquitous environment, some handover schemes and improvements were proposed by the IETF in order to support mobility effectively. In addition, mobile Stream Control Transmission Protocol (mSCTP) proposed by the IETF is a new transport protocol supporting mobility and with a built-in feature called Multi-homing has attracted much attention from the research communities. Multi-homing is convenient to introduce IP diversity in mobility management. A seamless handover architecture called SIGMA based on mSCTP has better performance than Mobile IPv6 enhancements. However, the handover performance in SIGMA remains low if the mobile host moves at a fast speed. Aiming at this problem, we propose SHSBM, a Smooth Handover Scheme based-on mSCTP. SHSBM adopts the advantage of SIGMA, and utilize Buffer and Tunnel to better serve fast-moving users. Additionally, we propose two strategies to solve the problem caused by Buffer-scheme—sequence Out of Order. Criteria for performance evaluation including the packets’ loss rate, throughput and handover latency compared with SIGMA and Mobile IPv6 enhancements.     

SCTP故障恢复机制改进

流传输控制协议（SCTP协议）是一种新的Internet传输层协议,Internet工作组设计SCTP的最初目的是在IP网络上传输PSTN信令消息,而且还能够充当通用传输协议。与传统的传输协议相比,SCTP协议允许在一个单一的连接中传输多个数据子流,这种功能可以大大改善高损耗的环境中多媒体流延迟问题,同时SCTP协议支持多宿功能,能够为网络提供冗余备份功能。对SCTP故障恢复机制进行了改进,充分利用SCTP多宿特性为移动Ad hoc网络提供可靠性保障,使其能够适应移动Ad hoc网络的特点,仿真结果表明：该功能极大地减少了故障恢复时间,提高了其在移动Ad hoc网络中的性能。     

A new method to support UMTS/WLAN vertical handover using SCTP

This article proposes a new method to facilitate seamless vertical handover between wide area cellular data networks such as UMTS and WLANs using the stream control transmission protocol (SCTP). The multihoming capability and dynamic address configuration extension of SCTP are applied in UMTS/WLAN overlay architecture to decrease handover delay and improve throughput performance. Unlike techniques based on mobile IP or session initiation protocol, the SCTP-based vertical handover scheme does not require the addition of components such as home/foreign agents or a SIP server to existing networks. Therefore, the proposed scheme provides a network-independent solution preferred by service providers. Performance evaluations are presented to demonstrate the effectiveness of the proposed scheme.     

一种SCTP报文的NAT穿越方法

流控制传输协议（SCTP）即将成为下一代网络中的传输层协议,在未来互联网和移动网络中发挥重要作用,然而目前网际协议（IP）网络中大多数网络地址转换（NAT）设备对SCTP报文转发缺乏兼容性支持。分析并解决了SCTP在当前IPv4网络实施中所遇到的NAT阻断问题。利用在收发端协议栈上进行功能扩展,提出了一种新的SCTP报文的NAT穿越方法,在不修改当前网络NAT设备的前提下完成NAT穿越,并在原型机上测试验证了解决方案的可行性和有效性。     

Adaptive Congestion Control of mSCTP for Vertical Handover Based on Bandwidth Estimation in Heterogeneous Wireless Networks

This paper proposes a new congestion control scheme of mobile Stream Control Transmission Protocol (mSCTP) for vertical handover across heterogeneous wireless/mobile networks. The proposed scheme is based on the estimation of available bandwidths in the underlying network as a cross-layer optimization approach. For congestion control of mSCTP, the initial congestion window size of the new primary path is adaptively configured, depending on the available bandwidth of the new link that a mobile node moves into. By ns-2 simulation, the proposed scheme is compared with the existing congestion control schemes in the throughput perspective. From the numerical results, we can see that the proposed mSCTP congestion control scheme could give better performance than the existing schemes in the wireless networks with an amount of background traffic.     

IPTV QoS adaptation for multi-homed mobile terminals in a new IMS based architecture

With the emergence of multimedia applications that have real constraints, ensuring a satisfying quality of service to mobile users presents a big challenge in heterogeneous wireless networks. In such environment, the asymmetry of the available resources as well as user’s mobility can cause offered QoS degradation. In this paper, we propose the use of the Stream Control Transmission Protocol (SCTP) within a QoS adaptive IPTV services in a novel IMS architecture. The multi-homing feature and the partial reliability extension allow improving the network performance and increasing the user satisfaction. In addition, we have proposed an mSCTP based mobility scheme to guarantee service continuity during handover to IPTV users over IMS. The handover decision includes Perceived QoS (PQoS) measurement reflecting the user satisfaction and Media Independent Handover (MIH) information. An analytical study of the time required to perform IPTV adaptation, show that our approach improves the performance by minimizing the delay and maximizing the user satisfaction.     

基于流传输控制协议的移动切换研究

传输层的移动SCTP可支持无缝的移动切换，而不需要网络路由器的支持，SCTP的移动切换性能主要是由在关联中加入和改变IP主地址的触发机制决定。本文针对具体的切换实现进行了分析研究，提出了预切换的可行性方案。     

移动流媒体关键技术及其平台实现

随着移动通信的迅速发展,移动流媒体成为移动通信发展的新热点,第三代移动通信(3G)标准的制订使得通过无线信道传输视频信息成为可能.介绍了移动流媒体技术的基本特征,阐述了移动流媒体的关键技术,包括网络协议、系统结构、QoS控制等,最后介绍了基于RealSystem的移动流媒体平台的实现.     

A Novel End-to-End Architecture for H.264 Video Streaming over the Internet

In this paper we propose a novel end-to-end architecture for H.264 unicast video streaming over the Internet. The proposed video streaming architecture is based primarily on a new transport layer protocol, the stream control transmission protocol (SCTP). We show that the network-friendly specification of H.264, and the novel technical characteristics of SCTP, when coupled together are able to provide a highly adaptive and flexible system for unicast video streaming. More specifically, we develop algorithms that handle at the transport layer the following functions concerning video packet transmission: retransmission policy, packet prioritization, implicit receiver feedback. We combine the above algorithms with an R-D optimization strategy at the encoder, that provides more options when adapting to bandwidth variations. This combined optimization strategy leads to more options concerning the streaming parameters. Finally, with simulation results we prove that our system is capable of maintaining good perceptual quality and TCP-friendliness under various loss conditions. An early version of this paper appeared in CCNC 2004.