一种基于TMS320VC5471的IP电话

从技术的角度分析IP电话的发展历程,在此基础上提出并实现了一种基于TMS320VC5471的独立式IP电话终端设计方案,采用ARM/DSP双处理器结构,语音编解码算法由DSP处理,增强了系统的实时性,它有一个RJ-45以太网接口,能够直接接入因特网,实现和其它IP电话或普通电话通话;给出了硬件和系统软件的构成,并指出了系统需要进一步改进的地方。     

基于MIPv6的异质无线网络的无缝切换策略

由于无线网络技术的多样性,用户在采用不同接入或存取技术的无线网络间的无缝切换是一个非常重要的课题,本文提出一种新的基于MIPv6的WLAN与GPRS网络融合方案和在这种结构下的无缝切换机制。     

基于软交换的IP电话在天水广电多媒体信息网的应用

IP电话通常称作Internet电话或网络电话,是利用因特网传递数字信号并实现通话的一种先进的通信方式,IP电话使广电网络同时处理语音、图像和数据信息而向三网合一的方向迈进,软交换技术的发展是大势所趋,天水广电已建设成基于软交换的IP多媒体电话系统.     

市场

爱立信实现全球首个LTE与WCDMA语音切换 本刊讯 日前,爱立信与高通公司合作,利用基于3GPP标准的单信无线主意呼叫连续性技术（SRVCC）,成功实现了全球首个LTE与WCDMA之间的话音切换。正在通话过程中的用户在离开LTE覆盖范围时,语音通话将被自动切换到WCDMA或GSM模式,确保用户无缝通话的良好体验。SRVC使运营商能够部署LTE语音业务并根据需要无缝切换到现有的GAM和WCDMA基站。     

基于MIPv6的异质无线网络的无缝切换策略

由于无线网络技术的多样性，用户在采用不同接入或存取技术的无线网络间的无缝切换是一个非常重要的课题，本提出一种新的基于MIPv6的WLAN与GPRS网络融合方案和在这种结构下的无缝切换机制。     

基于Diameter的L2异构网络切换

4G系统由IP骨干网和各种无线接入网组成,不同接入网络并存使得具有多模配置的移动终端可以同时连接到多个物理网络。如何安全并无缝地接入IP骨干网成为MN在异构网络漫游中需要解决的首要问题。在分析了移动IP技术和移动以太网技术的基础上,提出了一种基于L2分层的安全的切换模型。把对MN的安全认证放在L2接入的第一时间进行,L3切换时无需进行安全认证,从而降低了L3切换的时延。     

基于软交换的IP电话在天水广电多媒体信息网的应用

IP电话通常称作Internet电话或网络电话，是利用因特网传递数字信号并实现通话的一种先进的通信方式，IP电话使广电网络同时处理语音、图像和数据信息而向三网合一的方向迈进，软交换技术的发展是大势所趋，天水广电已建设成基于软交换的IP多媒体电话系统。     

一种基于SIP与移动IPV6的异构网络切换方法

随着移动通信技术的发展,诞生了各种可供接入的网络,如GPRS,WALN等.它们传输速率和原理各不相同,不同异质接入网络之间的切换已经成为对下一代无线网络的一个基本要求.本文介绍了一种新的切换机制,首先分别介绍了SIP技术与移动IPv6技术的原理,然后结合SIP与移动IPv6技术提出一种全新的无缝切换机制,最后总结并提出了有待进一步研究的相关问题.     

基于SIP协议的智能ATA的设计

本文介绍了基于SIP协议的通信终端产品ATA的设计。ATA是一种多功能的智能电话接入适配器,融合了传统的通信方式和先进的网络通信技术,拥有PSTN和IP两种网络的号码,能为用户提供便利的通信选择,音质好,费用低,可以实现两种电话模式的通话功能和互通。     

基于IP承载网上语音增值业务案例分析

通信行业中传统的语音业务是通过2M线路接入程控交换网上,现在随着IP技术的不断广泛应用,IP承载网的投入使用,使的语音增值业务的接入点也随之发生改变,从而使呼叫中心等业务的设备、组网发生改变.目前省一级新增语音增值业务,已接入省NGN,当此类平台出现通话异常时,对障碍的排查,与传统模式下接入的语音业务已有所不同,现就针对一起接入NGN的呼叫中心出现的单通问题进行分析说明.     

End-to-End Adaptive QoS Provisioning over GPRS Wireless Mobile Network

The General Packet Radio Service (GPRS) offers performance guaranteed packet data services to mobile users over wireless frequency-division duplex links with time division multiple access, and core packet data networks. This paper presents a dynamic adaptive guaranteed Quality-of-Service (QoS) provisioning scheme over GPRS wireless mobile links by proposing a guaranteed QoS media access control (GQ-MAC) protocol and an accompanying adaptive prioritized-handoff call admission control (AP-CAC) protocol to maintain GPRS QoS guarantees under the effect of mobile handoffs. The GQ-MAC protocol supports bounded channel access delay for delay-sensitive traffic, bounded packet loss probability for loss-sensitive traffic, and dynamic adaptive resource allocation for bursty traffic with peak bandwidth allocation adapted to the current queue length. The AP-CAC protocol provides dynamic adaptive prioritized admission by differentiating handoff requests with higher admission priorities over new calls via a dynamic multiple guard channels scheme, which dynamically adapts the capacity reserved for dealing with handoff requests based on the current traffic conditions in the neighboring radio cells. Integrated services (IntServ) QoS provisioning over the IP/ATM-based GPRS core network is realized over a multi-protocol label switching (MPLS) architecture, and mobility is supported over the core network via a novel mobile label-switching tree (MLST) architecture. End-to-end QoS provisioning over the GPRS wireless mobile network is realized by mapping between the IntServ and GPRS QoS requirements, and by extending the AP-CAC protocol from the wireless medium to the core network to provide a unified end-to-end admission control with dynamic adaptive admission priorities.     

A push mechanism for GPRS supporting private IP addresses

The General Packet Radio Service (GPRS) provides a packet switched data service for mobile users. However, the existing GPRS specification does not provide the push mechanism and it is difficult to support GPRS services such as call termination (incoming call) for wireless voice over IP (VoIP). Based on the short message service, this paper proposes a push mechanism for GPRS supporting private IP addresses. Our approach does not need to modify the existing GPRS structure.     

WLAN接入GPRS核心网的认证机制

无线局域网和移动运营商网络结合起来，利用现有GPRS核心网强大的管理功能和漫游能力，可以拓展无线局域网的业务范围。这一方案中，只有控制信息被传输到移动核心网，而用户数据直接通过IP骨干网传输，这样可以极大地缓解无线数据业务对移动核心网的负荷。如何利用IP机制将移动用户认证信令从终端传到GPRS核心网是设计的难点。本着重分析认证机制及其相关协议。     

Wireless Internet access for mobile subscribers based on theGPRS/UMTS network

With the advent of IP technologies and the tremendous growth in data traffic, the wireless industry is evolving its core networks toward IP technology. Enabling wireless Internet access is one of the upcoming challenges for mobile radio network operators. The General Packet Radio Service is the packet-switched extension of GSM and was developed to facilitate access to IP-based services better than existing circuit-switched services provided by GSM. We illustrate how a visited mobile subscriber on a GPRS/UMTS network can access his/her home network via the gateway GPRS support node (GGSN). We also propose some implementation ideas on wireless Internet access for a remote mobile subscriber based on a GPRS/UMTS network     

Charging Information Collection Modeling and Analysis of GPRS Networks

Charging is one of the most important functionalities in a telecommunication service system. In a general packet radio service (GPRS) wireless network, the load of charging information flow depends on the intensity of call traffic and the size of charging records. During busy hours, the GPRS network might not be able to transfer charging records on a timely basis if new charging records are generated too fast. On the other hand, when a call happens, the related charging information must be collected and transferred to the billing system. If a failure of the data link occurs, a secondary data link must be employed to transfer the charging information. However, this redundant operation might result in charging information duplication. This paper formally addresses these two issues. A timed Petri net model is built to support the analysis of the charging system performance versus various factors when the system works in the normal status, which, in particular, gives the maximum supportable busy hour call attempts of the GPRS network. The Petri net approach is also used to model and verify the correctness of the redundancy operation in case a connection failure occurs.     

Efficiency of the GSM-GPRS Air Interface for Real-Time IP Traffic Flows With and Without Packet Dropping

One IP terminal can occupy a single slot or a multiple number of slots within time frames in the GSM and GPRS, respectively. A limited number of radio resources (slots) are allocated in a base station for such IP terminals. If one IP terminal can occupy only one slot discontinuously in a time frame, there is one possibility resorting to all IP terminals to preserve active mode at a time. Thus, the number of accepted call in the GSM is the same as that of the radio resource. Similarly, if one terminal can occupy a multiple number of slots discontinuously/dynamically in a time frame, the number of accepted calls is obtained by dividing the number of radio resources during that time by the maximum allowed number of slots per IP terminal. A burstiness factor is defined for the IP traffic over GSM-GPRS air interface. Traffic channel efficiency with a bursty real-time IP traffic is unacceptably low, especially with the range of acceptable call loss probabilities pertaining to a lower burstiness factor. The channel efficiency can be enhanced and the call loss probability can be suppressed significantly if a higher maximum number of calls is accepted. Allocated radio resources are less than the maximum number of packet transmissions at a time. Therefore, some packets could be dropped from the real-time transmission system. A complete analysis for the real-time IP packet transmission over the single slot GSM and dynamically variable multislot GPRS air interface without packet dropping, and with packet dropping that increases the channel efficiency is executed. Results show that the channel efficiency as well as the packet dropping probability increases with increasing call intensity, maximum number of admitted IP calls and the burstiness factor.     

vGPRS: A Mechanism for Voice over GPRS

This paper proposes vGPRS, a voice over IP (VoIP) mechanism for general packet radio service (GPRS) network. In this approach, a new network element called VoIP mobile switching center (VMSC) is introduced to replace standard GSM MSC. Both standard GSM and GPRS mobile stations can be used to receive real-time VoIP service, which need not be equipped with the VoIP (i.e., H.323) terminal capabilities. The vGPRS approach is implemented using standard H.323, GPRS, and GSM protocols. Thus, existing GPRS and H.323 network elements are not modified. Furthermore, the message flows for vGPRS registration, call origination, call release and call termination procedures are described to show the feasibility of our vGPRS system.     

TCP/IP在GPRS/EGPRS网络中的应用及影响

通用分组无线业务/增强型数据速率演进技术（GPRS/EGPRS）服务扩展了当前世界上最流行的第二代移动系统——基于语音的GSM,使其能够收发基于分组的数据。随着移动通信技术的发展和业务的多样化,人们对数据业务的需求不断增加,GPRS/EGPRS网络优化也成为了重中之重。除传统的无线网络及核心网络优化外,将其以端到端的思路分析,看为无线＋IP网络技术,成为了新的优化思路。因此传输控制协议/因特网互联协议（TCP/IP）作为互联网固有的最为广泛的传输协议在无线分组数据业务网络中同样得到广泛应用。主要就TCP/IP协议在GPRS/EGPRS中的应用其影响进行了分析。     

Performance evaluation of a reservation random access scheme for packetized wireless systems with call control and hand-off loading

We consider a packet switched wireless network where each cell's communication channel is shared among packet voice sources. In this paper, we present a method for the design and analysis of wireless cells using a reservation random access (RRA) scheme for packet access control. This scheme is integrated with a call admission control procedure. We model the state process of a single cell as a vector Markov chain. We compute the steady state distribution of the Markov chain. This result is used to calculate the packet dropping probability and the call blocking probability. By setting limits on maximum permissible levels for the call blocking probability and the packet dropping probability, we obtain the Erlang capacity of a single cell, with and without hand-off traffic. For an illustrative RRA scheme, the Erlang capacity of a single cell is shown to be about twice that attained by a comparable fixed assigned TDMA scheme. We show that a cellular network using this RRA scheme and which applies can be no blocking of hand-off calls, exhibits similar call capacity levels.This work is supported by a University of California MICRO and Pacific-Bell Grant No. 94-107.     

一个可切实服务于运营商的移动无线因特网

本文在简单介绍了移动IP及其路由优化，无线局域网（WLAN）和GPRS的基础上，提出了一个新的利用移动IP来融合WLAN和GPRS的移动无线因特网的网络结构，详细论述了其多连接的路由过程，平滑垂直切换，AAA，并做了简要的性能分析。