Throughput Performance of Wireless Networks

Abstract

The advancement in wireless communication technologies have resulted in the evolution of wireless networks from the traditional circuit-switched networks which initially support voice calls to packet-switched networks which support data transmission at variable rates. The exibility and eciency of packet-based networks are further enhanced in fourth generation (4G) networks through the use of Orthogonal Frequency Division Multiplexing (OFDM) technology. These technological developments are driven by the rapid increase in demand for high speed mobile data. Throughput is an important performance measure used to quantify the performance of packet-based networks. Providing high capacity wireless networks that are able to support high throughput requirements within the constraint of nite bandwidth resource is crucial and has been the motivation of this thesis. The work in this thesis focuses on providing high capacity wireless networks by understanding the key parameters that aect the throughput performance. Received signal quality and bandwidth allocation are the key factors that aect the throughput performance. Received signal quality may vary under dierent propagation environments due to the variation of user location and base station (BS) deployment strategy. Depending on the users' received signal quality and throughput requirement, dierent amount of bandwidth can be allocated to the users through scheduling. This thesis presents the investigation of throughput performance for downlink OFDM wireless networks where estimates of the received signal quality in the Physical (PHY) layer is incorporated with scheduling of bandwidth resources in the Media Access Control (MAC) layer. This investigation is performed for both outdoor and indoor environments and considers two types of scheduling scheme, namely Maximum Rate (MR) and Equal Allocation (EA) Scheduling. A cross-layer trac model is used to compute the throughput performance for a specic mean arrival rate under varying propagation environment and scheduling scheme. Results obtained reveal that depending on the throughput requirement, a particular BS deployment and resource allocation strategy may be preferred to provide ecient wireless network performance. The investigation carried out in this thesis is not restricted to any wireless network standards hence the guidelines on system design derived from the ndings obtained can be applied to any packet-based wireless networks that utilize the OFDM technology.