Performance analysis of CDMA data networks with rate and delay variations
Vikas Paliwal · 2004
The behavior of wireless links in third generation wireless data systems based on cdma2000 standard have profound impacts on the performance of transport layer protocols. This is due to greater variations in round trip times (RTTs) experienced by the TCP agents over these links, primarily due to two reasons error recovery through link layer retransmissions and allocation/de-allocation of higher data rate channels. In this thesis, an exhaustive study of the nature and impacts of these two features is presented. Based on simulations and analysis, this thesis makes the following key contributions: First, the conditions under which sharp delay variations and residual errors occur in presence of link layer recovery mechanisms are identified and the impacts of these in degrading the system performance and TCP throughputs is presented based on an implementation of cdma2000’s link layer protocol, Radio Link Protocol(RLP), that was developed as part of this work. The second part of this thesis quantifies the problem of network congestion due to variable rate radio links. This problem is characterized using an analytical model for losses based on continuous flow approximation as well as an extensive simulation setup. We investigate this problem under variety of scenarios and suggest possible solutions to counter the problem.