Modeling and performance analysis of OFDM based multi-hop cellular networks

Abstract

The growth of wireless multimedia applications, such as real-time video or multimedia broadcasting services, requires high-speed and reliable communication over wireless channels. Recently, there has been increasing interest in multi-hop relaying and orthogonal frequency division multiplex (OFDM) for cellular networks, due to their ability of capacity enhancement, coverage extension and cost reduction. To achieve these advantages concurrently, an accurate performance analysis of OFDM based multi-hop is one of the most important issues, because it makes possible to optimize system design in the consideration of complex interactions between, routing, medium access control and resource allocation. Therefore, in this thesis, we focus on the accurate performance analysis of OFDM based multi-hop cellular networks. First, we develope an appropriate fading model for OFDM system analysis. Specifically, we propose an approximation method for the channel impulse response of a specific OFDM subcarrier over frequency-selective Nakagami-m fading. Using fading figure matching as a basis, we show that a frequency domain channel can be approximated by Nakagami-q (Hoyt) and Nakagami-n (Rice) models. The proposed approximation scheme is accurate in that the approximated envelope distribution is almost optimum in terms of root mean square error (RMSE), simple in that the fading parameters are explicit functions of the fading parameters of the frequency-selective channel, and flexible in that it is applicable to all power delay profiles. Second, using the developed channel model, an exact queuing analytical model is studied to evaluate quality of service (QoS) metrics in the downlink of multi-user OFDM system. At first, we derive average transmission error rate of physical layer protocol data unit under the consideration of an adaptive modulation and coding (AMC) scheme. To find out the joint effect of the AMC, packet fragmentation and finite queue length on the performance of ...