Quality of service and performance issues in multiservice networks subject to voice and video traffics

摘要

Third generation networks tend to integrate an ever increasing number of services. Thus, standards and protocols such as the UMTS and Wireless Access Protocol (WAP) should allow any mobile user, in addition to telephony, to navigate the Web, have a videoconference call, etc. However, the integration of services raises a certain number of problems. For example, the advent of new services (such as the Internet) has questioned the traditional traffic models used in the telecommunications world. New models have then been proposed to take into account bursty and self-similar traffic. But in third generation networks, even if several studies have been dedicated to the analysis of the performance of radio technologies, few have been done on the analysis of these networks from an application perspective, when various types of traffic are aggregated. In this paper, the focus is on the performance issues arising in UMTS third-generation wireless networks, subject to voice and video traffics. For that purpose, we adapt existing traffic models or propose new ones, which are based on the UMTS forum specifications and real traffic observations. The models obtained are calibrated and validated by comparison with real traces and used to simulate a UMTS network aggregating various types of traffic. This defines a reference model whose performance was evaluated according to certain metrics of quality of service (QoS). The performance achieved by the implementation is average because the throughputs suggested by the UMTS forum are a little restrictive. It is thus necessary in the design process to carefully define the QoS profiles associated with each class or application. For the streaming class, it would be necessary to install adequate buffers to ensure the quality of service, particularly end-to-end delay. Also, the addition of another QoS management layer has shown to improve the performance.