This thesis addresses optimization issues in dynamic multi-user OFDM systems. The investigations are focused on the down-link of a single wireless cell. Dynamic sub-carrier assignments to terminals are periodically generated by the access point based on channel predictions. Several issues are considered in this context. First, the thesis investigates optimal and suboptimal assignment strategies...

Vector quantization is very efficient for data compression of speech and image. The channel distortions are introduced due to channel noise. Assigning suitable indices to codevectors can reduce distortion due to an imperfect channel. Several codebook index assignment algorithms were proposed. Unfortunately, no algorithm is always better than the others for any bit error rate due to these algori...

A multihop Dynamic Channel Assignment Scheme is proposed here for Multihop Cellular network. The proposed scheme splits the cell into microcell and macrocell to accept and complete the call as single hop, two hops, or three hops call. The radio resources are assigned to each call based on the interference information in the surrounding cells, stored in Interference Information Table at MSC. Two...

Equipping mesh nodes with multiple radios that support multiple wireless channels is considered a promising solution to overcome the capacity limitation of single-radio wireless mesh networks. However, careful and intelligent radio resource management is needed to take full advantage of the extra radios on themesh nodes. Flow-radio assignment and channel assignment procedures should obey the ph...

Hyancinth is one of the popular node architectures proposed by Ashish et al. for efficient channel assignment in multi-radio multi-channel(MRMC) wireless mesh network(WMN). However, we found out that Hyacinth was designed without considering the security mechanism. A fake channel control packet from an external attacker can degrade the network goodput. Also, an internal attacker e.g., compromis...

This paper presents a channel sharing scheme, Neighbor Cell Channel Sharing (NCCS), based on region partitioning of cell coverage for wireless cellular networks. Each cell is divided into an inner-cell region and an outer-cell region. Cochannel interference is suppressed by limiting the usage of sharing channels in the inner-cell region. The channel sharing scheme achieves a traffic-adaptive ch...

Adaptive resource allocation can drastically increase the throughput of an Orthogonal Frequency Division Multiple Access (OFDMA) system when the Channel State Information (CSI) is accurately known. Unfortunately, in practice, perfect CSI is rarely possible. In this paper, we consider adaptive subcarrier assignment for downlink multiuser OFDMA systems, where the transmitter has no knowledge of t...