On the Capacity Modelling in 3G Mobile Wireless Communications Systems

Abstract

Capacity issue was a major motivation behind the introduction of the present 3G mobile communication systems such as the wideband CDMA (WCDMA). However, the rapid increase in the number of connections and demand for high-speed multimedia communication services supported is contradicting with the limited resources allocated by these systems. WCDMA is an interference-limited system, which means that the capacity
bounds of these systems as well as coverage boundaries are continuously changing according to traffic conditions. WCDMA is designed to provide variable data rates, which further complicate the capacity analysis.

Active user capacity analysis in the Universal Mobile Telecommunications System (UMTS) network of WCDMA is essential for different stages ranging from the initial network planning to the proper resource management of the operating network. The determination of upper bounds on the network's active-user capacity is needed to determine the traffic handling capability of the network and later in determining its performance.

Amongst the motivations for WCDMA is the possibility for capacity increase with the use of directional smart antennas to reduce the interference and therefore gain capacity increase. These are typically complex systems. One type that is simple enough yet beneficial in gaining capacity and coverage improvements in the WCDMA environment is called the Switched Beam Smart Antenna (SBSA). This work is about the analysis of the capacity/ coverage problem of WCDMA in a multiservice environment with the use of omnidirectional antennas at the base stations or with SBSAs. The analysis produced a distinctive model for the capacity and coverage in both cases whereby the number of users in each of the services, their coverage radii, activities, rates and other parameters in a multi-service UMTS environment are related
together at the boundaries of operation. The model provides a useful tool to analyse traffic and for radio resource management in UMTS especially that it links the problem of capacity sharing using WCDMA to the well-studied ATM statistical multiplexing
theories. The model with SBSA was used as a tool to asses the improvement gains against complexity when the antenna at the base station is of the switched beam type.

Date of Award	Jul 2008
Original language	English
Supervisor	Khalid Al-Begain (Supervisor)