【作者】 林波；

【导师】 谭建豪；

【作者基本信息】 湖南大学 ， 控制理论与控制工程， 2005， 硕士

【摘要】 随着分组网络的发展,电信运营商面临越来越激烈的竞争。为了提高他们的竞争力,他们不但要优化现有的语音网络,而且还要在数据网络上承载更多的业务。为了解决这一问题,基于软交换体系的下一代网络(NGN:Next Generation Network)应运而生。随着NGN各种协议的完善以及NGN的部署,NGN的发展成为了必然趋势。然而,目前NGN还有很多问题没有得到解决,如安全性与服务质量(QoS:Quality of Service)等。 本文顺应了NGN的发展趋势,以NGN网络和软交换为线索,对NGN和其服务质量进行了论述。首先从下一代网络的原理构架和其核心部件——软交换分析入手,主要研究了NGN的框架和分层结构以及软交换的语音编码、语音处理技术和软交换中的一些主要媒体网关控制协议。接着详细论述了这种网络构架下的通话质量问题以及产生问题的原因,得到了通话质量和NGN网络性能参数的对应关系,发现了承载网带宽不足是通话服务质量差的根本原因。因此提出了一种提高QoS的自适应语音编码的策略,它通过在应用软件根据网络的实时状况来选择不同的语音编码的方式来提高网络的QoS。最后在软交换的控制下,通过媒体网关控制协议H.248/MeGaCo控制媒体网关来实现。实验表明该策略能在一定程度上提高网络的服务质量。 提高NGN的服务质量势在必行。从应用层通过修改语音编码的方式来提高服务质量虽然不能彻底解决服务质量问题,但它可以作为其它策略的辅助方式。这种算法对带宽不足的网络有其优越性,对降低路由器的负荷也有一定的帮助。尤其对于带宽永远有限的无线通信,该自适应算法的优越性尤其明显。更多还原

【Abstract】 With the development of the network based on packet, carriers are faced with variety of challenges to converge their voice and data networks. They not only need to optimize their existent networks, but also offer new services in order to keep their competion and profit. To resolve these issues, the next generation distributed network architecture based on Softswitch technology has emerged to address these business challenges. With the establishment of various protocols and the arrangement of NGN network, it leads to the development of NGN naturally. However, there are still many problems on NGN have not been solved completely, such as security and QoS and so on.According to the development trend of NGN, the paper gives a comprehensive overview of NGN and its QoS base on NGN and Softswitch. The paper starts with the brief interpretative introduction of architecture framework and softswtich which is the core parts of NGN. And then the paper analyzes the problem of QoS and Why the QoS is bad. The paper discovers the sticking point of QoS by discussing the corresponding relation of QoS of NGN and performance parameters of network. At last the paper brings forward a strategy that exchanges the speech coding dynamic to improve the QoS of NGN. It is proved that the strategy can improve the QoS of NGN in a way.To improve the QoS of NGN is very necessary. The strategy that exchanges speech coding can’t resolve the problem of QoS thoroughly, but it can improve QoS auxiously. It has the superiority to the network shortage of bandwidth recently and has the certain help to lower the burden of the router also. Especially it has superiotity to wireless communication that the bandwidth is limited forever.更多还原