How to minimize the TCP effect in a UMTS‐HSDPA system?

Abstract

AbstractThis paper focuses on the interaction between the transmission control protocol (TCP) layer and the radio interface in a 3G wireless system. An analytical model to evaluate the impact of TCP on the UMTS‐HSDPA capacity is presented. A method to minimize the effect of TCP on wireless networks using shared channels is also proposed. High speed downlink packet access (HSDPA) is an evolution of the UMTS standard over the air interface to achieve higher aggregate bit rates through the introduction of adaptive modulation and coding, hybrid automatic repeat request (ARQ), fast scheduling, fast cell selection, and multiple input multiple output (MIMO) (space time coding and blast) techniques. The proposed model is used to evaluate the effect of the TCP protocol on the bit rate of various data services (at 64 and 128 kbps). As expected, the bit rate per flow decreases strongly if the congestion frequency in the wired network increases. However, the overall capacity achieved by HSDPA is not as affected by the TCP layer. Using this result, a method to maintain the bit rate per TCP flow at a given value without loosing much cell capacity is proposed. The findings are supported by simulation results. Copyright © 2005 John Wiley & Sons, Ltd.