A Novel Software-Based H.323 Gateway with Proxy-TC for VoIP Systems

• Main Authors: Wei-Sheng Yin, 殷偉盛
• Other Authors: Po-Ning Chen
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/98753009997947557570

碩士 === 國立交通大學 === 電信工程系 === 89 === In this paper, we present a novel architecture for software-based H.323 gateways that operate over PC platforms. It is motivated by two observations. First, we found that the computation load of a software-based H.323 gateway is mainly contributed by media transformation activities, such as the transcoding of voice streams. We also observed that the CPU computation power of an IP call terminal (which is a PC in our system setting) or a software-based H.323 gateway may be unevenly switched to another task by the operation system; hence, an active IP call may experience occasional interrupts. We therefore propose a proxy—transcoder (proxy-TC) architecture to balance the computation load of, as well as to smooth the fluctuation of dedicated computation powers to, the IP call activities. Our simulation showed that both the system capacity and the new call blocking probability can be significantly improved under our proposed architecture. Besides, by adding an additional TC-handoff mechanism, the active call dropping probability can be drastically decreased at the expense of a little increase in the new call blocking probability.