A Study Of Unified Communication System Providing QoS Guarantee

With the development of wireless networks communication technology and the rapid popularization of the Internet application, user service are growing more diverse, and unified communication which integrates a variety of user services has been becoming an important communication service today. In the face of various services and the increasing number of users, the traditional "best effort" model for data transportation has been unable to meet the users’requirement for network QoS (Quality of Service) in the resource limited wireless network. Such that, it becomes a key problem to the development of unified communications in the field of wireless communication.Firstly, a brief introduction to the basic theory of network QoS, including the basic concept, service model and the related packet scheduling algorithm, is given in this thesis. Then, the application environment and QoS requirement of end user fcr unified communication system were analyzed, and a new QoS service model which integrates IntServ and DiffServ model together was proposed. We applied this model to the application server of the unified communications system to provide guaranteed QoS for user service. After that, the communication and QoS requirements of various kinds of user systems in a special multi-domain network environment were analyzed, and a technical solution with cooperation of related user system to provide guaranteed QoS is designed in this thesis.Finally, according to the proposed solution, a unified communication system framework with guaranteed QoS was built and the detailed design and implementation of service module was given in this thesis, including guaranteed QoS module, unified communications terminal module, terminal agent module and the simulation test module, etc. Furthermore, we focused on packet scheduling algorithm of QoS module and a new packet scheduling algorithm applicable to the special multi-domain network environment is designed. On the other hand, terminal agent is adopted in this thesis to isolate the user service with carrier network for unified communication, which was also optimized to increase the transmission efficiency of the upper application system.We implemented the proposed solution in Windows Server 2008 operating system, and complete the integration and debugging of the whole communication system in a special multi-domain network environment. The test results show that for user services with various QoS requirements, the application server proposed in this thesis can provide the required QoS guarantee.