3G网络BCMCS标准研究

BCMCS可以使组播IP流在空中只传输一份拷贝,多个用户接收,从而大大节省空中链路带宽,有效地提高服务质量和整体吞吐量,同时也能将费用降低到用户可以接受的水平。可以说,BCMCS技术使得通过移动通信网络提供高质量的广播业务成为可能。本文主要介绍了BCMCS的网络参考模型、协议栈和业务功能等方面的内容。     

CDMA移动广播业务中的关键技术研究

文章对与CDMA2000密切相关的手机电视标准BCMCS、MediaFLO和CMMB作了简单介绍,并对两种运营模式的优劣势进行了对比分析,接着提出了一种移动网络与广播承载网络相结合的系统架构,具有较强的可运营和可管理性。为了控制用户接入,实现运营商利益最大化与用户个性服务质量最优化,必须要有一套健全的业务保护体系,文章对目前各种保护方案的特点进行了分析,给出了一种SIM卡与CA结合的业务保护方案。     

一种应用于网络广播的动态广告分发技术

随着新媒体时代的快速发展,互联网广播日益成熟,相对传统广播仅能单向传输的技术特点,互联网广播的双向交互能力为网络广播带来了新的商机.本文介绍的网络广播的动态广告分发方案结合了语音识别、关键词匹配等技术,将实现根据用户正在收听的节目内容向用户实时推送与内容相关的广告链接的功能.这一功能能够减少广告预处理的人力与时间成本,并且可以实现实时节目流动态广告匹配,有助于开启网络广播广告生产和运营的新模式.     

移动网络中的广播多播业务

本文主要介绍了3GPP和3GPP2中的广播和组播业务。首先叙述了在移动网络中引入广播组播业务的必要性，然后，描述了MBMS和BCMCS的网络结构，并分别介绍了GSM、WCDMA和CDMA2000中的无线承载。     

CDMA2000广播-多播业务的安全研究

文章对CDMA2000的广播-多播业务BCMCS安全所涉及到的功能结构、密钥管理和算法进行了研究分析。首先,给出了BCMCS安全功能实体的逻辑结构,重点研究了BCMCS密钥管理和密钥分发流程;其次,探讨了BAK的认证、存储、更新以及BCMCS涉及到的安全算法;最后,对全文进行总结,指出了关于BCMCS安全的有待于进一步研究的几个问题。     

cdma2000中的广播和组播业务

本文对cdma2000中BCMCS(广播和组播业务)进行了介绍,主要涉及BCMCS的总体要求、业务功能、网络框架和承载路径的建立和鉴权等方面.     

移动多媒体标准BCMCS及其与MBMS的对比

BCMCS概述 BCMCS广播和多播(组播)业务是根据实际应用而提出的.移动用户的应用通常分为一对一的个性化单播业务(Unicast),即每个用户根据其需求,选择各自不同的应用,如电子邮件、网页浏览、个性化的媒体流下载、图片信息的传送等等.另一种应用即为一对多的公共信息业务,即同一种业务服务于每一个用户(Broadcast)或一组用户(Multicast),如天气预报、股票、新闻、体育转播等.     

支持下载业务的移动多媒体广播业务方案分析

分析了实现移动多媒体广播的几种方案,并提出一种基于混合网络、同时支持下载业务的移动多媒体广播业务实现方案。本方案通过移动网络实现业务管理,采用分层密钥管理体系提高系统安全性,同时引入DRM(digital right management)模块,支持节目片段下载的业务。该方案对于实现移动多媒体广播业务的运营管理以及与下载业务的融合有着重要的意义和应用价值。     

客服智能手机终端移动工单管理系统的设计与应用

移动工单系统是数字电视客户呼叫中心平台系统的延伸,它结合最新的网络移动技术,实现数字电视服务工单分派业务的自动流转和实时流转,各地市维护站的服务工作人员通过智能手机终端实时获取工作任务、计划安排,进行业务处理,通过移动网络查询客户信息．查询用户产品订购资料、上报处理结果和用户反馈信息,通过移动网络提交到管理部门,管理层能及时地掌握服务进展情况,并能随时做出决策和指挥。真正实现对用户最快速、     

移动定位系统的实现原理和方法

移动定位系统(LBS)作为一种移动增值业务的平台,提供移动用户位置信息服务和用户准确位置定位服务。定位平台从移动网络中得到移动用户的位置信息,并将此位置信息通过特定的标准接口传输至位置服务平台(即CP),以实现向用户提供位置服务信息的功能。定位平台应具有以下特性:(1)定位平台独立于移动网和互联网,在移动网和互联网之间提供位置信     

BCMCS无线传输技术分析

本文针对BCMCS(广播与组播业务)技术标准,提出了BCMCS无线传输的技术要求,并通过分析其主要的无线传输技术,特别是差错控制技术、信道分配技术、高效传输技术和接收增强技术,说明其无线传输的技术特性.     

Performance of Broadcast and Multicast Service with Interference Cancellation Based on Macro Diversity

The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services(BCMCS) to meet an increasing demand for multimedia data services.Single frequency network(SFN) is recognized as an effective way to improve the spectral efficiency of the BCMCS system.To improve the coverage and the data rate of the BCMCS users,an interference cancellation algorithm based on macro diversity is introduced in this paper.The performance of BCMCS in CDMA2000 EV-DO networks under the condition of SFN is evaluated.The simulation results show a significant improvement in bit error ratio(BER) while quantitatively validating the efficiency of our approach.     

Timing evaluation of MAC-layer error control on ARM9-based mobile embedded systems

BCMCS (Broadcast and Multicast Services) are designed to provide media broadcast in cellular networks. In designing media broadcast protocols and systems, such as BCMCS, delay must be thoroughly considered because it is the key QoS parameter in multimedia applications. This paper investigate the forward error correction (FEC) delay using Reed-Solomon (RS) code related to the temporal behavior of Rayleigh fading. We implemented the evaluation framework for the RS decoding delay employing analytic and simulation-based approaches. An analytic method and a simulation approach are combined in a unified environment exploiting Java programming language, ARM9 processor simulator and Mathematica coupled together. This framework enables us to estimate various statistics required to ensure seamless multimedia services.     

cdma2000 1x EV-DO BCMCS技术及应用策略探讨

本文介绍了cdma2000 1x EV-DO BCMCS 技术原理,并对BCMCS的系统容量、带宽配置、内容保护等进行了分析,最后从无线、网络、业务、终端等多方面对应用策略进行了有益的探讨.     

Improved Error Control for Real-Time Video Broadcasting Over CDMA2000 Networks

The broadcast and multicast services (BCMCS) protocol is designed for real-time applications such as MPEG-4 video streaming, which requires successive frames to arrive within a specific time interval. We analyze the execution time of Reed-Solomon (RS) decoding, which is the medium access control (MAC)-layer forward error-correction (FEC) scheme used in CDMA2000 1xEV-DO BCMCS, under various air channel conditions. The results show that the timing constraints of MPEG-4 cannot always be met by RS decoding when the packet loss rate (PLR) is high, due to the limited processing power of current hardware. We therefore propose three error control schemes: First, we have our static scheme, which bypasses RS decoding at the mobile node to satisfy the MPEG-4 timing constraint when the PLR exceeds a given level. Second, we have the dynamic scheme, which corrects as many errors as possible within the timing constraint, instead of giving up altogether when the PLR is high; this improves quality. Third, we have the video-aware dynamic scheme, which fixes errors in a similar way to the dynamic scheme but in a priority-driven manner, yielding a further increment in video quality at mobile terminals. Extensive simulation results show the effectiveness of our schemes compared with the original FEC scheme.     

A Hybrid Error Recovery scheme for Scalable Video Transmission over 3G Cellular Broadcast Networks

The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services (BCMCS) to meet an increasing demand for multimedia data services. But the servicing of video streams over a BCMCS network faces a challenge from the unreliable and error-prone nature of the radio channel. BCMCS uses Reed-Solomon coding integrated with the MAC protocol for error recovery. We show that this is not effective for mobiles moving at the edge of service area, where the channel condition is bad, resulting in significantly lower video quality. To improve the playback quality of an MPEG-4 FGS (fine granularity scalability) video stream, we propose a hybrid error recovery scheme incorporating a packet scheduler, which uses slots saved by reducing the Reed-Solomon coding overhead. Packets to be retransmitted are prioritized by a utility function which reduces the packet error-rate in the application layer within a fixed retransmission budget by considering of the map of the error control block at each mobile node. Our error recovery scheme also uses the characteristics of MPEG-4 FGS to improve the video quality even for a slow-moving mobile which is experiencing a high error-rate in the physical channel because of error bursts. Kyungtae Kang received B.S. (1999) and M.S. (2001) degrees in computer engineering from Seoul National University, Korea. He received Ph.D. degree in Dept. of Electrical Engineering and Computer Science from Seoul National University, Korea in 2007. He is a member of IEEE and IEICE. His research interests include packet scheduling, error control, QoS provision, and energy minimization issues in nextgeneration wireless/mobile networks. In particular, he is researching the performance and energy requirements of 3G cellular broadcast services such as BCMCS and MBMS. Yongwoo Cho received the Premedical Degree from the College of Medicine, University of Ulsan, in 1997, a B.S. degree in Computer Science from Korea National Open University in 2004, while he was an military service, and an M.S. degree in Electrical Engineering and Computer Science from Seoul National University in 2006. He has worked as a researcher in Dooin Corp. and as a general manager in Bluecord Technology, Inc. His primary interests include multimedia systems, digital broadcasting, next-generation wireless/mobile networks, error control, real-time computing, and low-power design. He is currently a Ph.D. student in the School of Electrical Engineering and Computer Science at Seoul National University. Heonshik Shin received the B.S. degree in applied physics from Seoul National University, Korea, in 1973. Since he received Ph.D. degree in computer engineering from the University of Texas at Austin in 1985, he has actively involved himself in researches of various topics, ranging from real-time computing and distributed computing to mobile systems and software. He is currently a professor of School of Computer Science and Engineering at Seoul National University.     

SafeAnon: a safe location privacy scheme for vehicular networks

In most safety applications within vehicle ad-hoc networks (VANETs), vehicles need to periodically broadcast messages with information of their precise positions to others. These broadcast messages, however, make it easy to track vehicles and will likely lead to violations of personal privacy. Unfortunately, most of the current location privacy enhancement methodologies in VANETs suffer some shortcomings and do not take driving safety into consideration. In this paper, we propose a safe distance based location privacy scheme called SafeAnon, which can significantly enhance location privacy as well as traffic safety. By simulating vehicular mobility in a cropped Manhattan map, we evaluate the performance of the proposed scheme under various conditions. The mean entropy, warning broadcast ratio, and mean silent period of SafeAnon scheme are increasing 58%, 281%, and 50% respectively than the random silent period (RSP) scheme. The total broadcast ratio is also 33% less than that in the RSP scheme.     

A Water-Wave Broadcast Scheme for Emergency Messages in VANET

Vehicular Ad Hoc Network (VANET) is an emerging new technology and a promising platform for the intelligent transportation system. The most important application of VANET is disseminating emergency messages to drivers in case of dangerous events. The effectiveness depends on the design of a broadcast scheme. A simple broadcast scheme encounters many problems such as broadcast storm, connection hole, building shadow, and intersection problems. In this paper, we propose an efficient broadcast scheme that simulates water wave propagation to spread emergency messages. This scheme provides warning services with both space and time constraints. Most existing broadcast schemes provide inadequate strategies for limiting the time period of a warning. We verified the performance of our proposed scheme in a simulated street environment with vehicle movements to show the superiority of this scheme in high broadcast coverage areas.     

A New Transport Protocol for Broadcasting/Multicasting MPEG-2 Video Over Wireless ATM Access Networks

Because of the telecommunications de-regulation act and progress in wireless technologies, we will see the co-existence of heterogeneous broadband access infrastructures in the broadband video service industry in the near future. In this paper, we addressed the error control issue when transmitting MPEG-2 video streams over wireless access networks for broadband video broadcast or multicast services. An end-to-end transport protocol based on ATM and wireless ATM technologies is proposed. For video services, the underlying transport network should be transparent and quality should be maintained uniformly over all the segments whether wireline or wireless links. For network resources to be used efficiently, error control should be applied locally on the wireless segments so as to avoid the excessive overhead over the reliable wireline portions. Because a broadband video broadcast or multicast service is a one-to-multiple point service, FEC is the most prevalent error control mechanism. Due to the important role of MPEG-2 control information in the decoding process, priority MPEG-2 control information has to be differentiated from MPEG-2 data information, and excess error protection has to be allocated to it in order to achieve satisfactory QoS. Therefore, a header redundancy FEC (HRFEC) scheme for error control is applied at the local distribution centers before the MPEG-2 encoded video streams are transmitted over the wireless channels. HRFEC is an FEC-based selective protection scheme, which allocates extra error protection to important control information. Simulation results show that the quality of the reconstructed video sequence is vastly improved by using HRFEC, when the channel condition is poor.     

移动Ad Hoc网络分布式多跳认证授权方案

提出一个分布式的具有多跳认证授权支持的移动Ad Hoc网络方案。该方案利用门限密钥分享技术把认证授权功能完全分散化,每个节点持有一个密钥份额,只有达到门限值规定数量的节点联合起来才能提供认证服务,而认证服务将不仅仅局限于本地节点,多跳范围内的节点也可以参与这项工作。此外,本文还采用多播来取代广播以减少杂项开销。本文解决了多跳认证授权所遇到的技术难题,并通过仿真验证了方案的可行性和有效性。