Resource allocation issues in broadband wireless networks with OFDM signaling

The primary goal in a communications system is Quality of service (QoS) provisioning to users, which depends on procedures that span several communication layers. Cochannel interference between users that reuse the limited spectrum and the resulting impact, of local adaptation actions on overall network performance impose layer interactions in wireless systems. The purpose of this work is to identify and study some of the issues that arise from the synergy between the physical and the MAC layer in the context of multiple access schemes with orthogonal channels.; Using the essential feature of channel orthogonality as a baseline, our approach places emphasis on Orthogonal Frequency Division Multiplexing (OFDM), which is an emerging multiple access and signaling method for future wireless broadband networks. In OFDM, the broadband spectrum is divided into orthogonal, narrowband subcarriers and user symbols are split into subsymbols, which are transmitted in parallel over those variable-quality subcarriers. OFDM transmission reduces the effective symbol transmission rate, simplifies equalization at the receiver and provides high immunity to inter-symbol interference and delay spread.; We first address the joint problem of channel allocation with simultaneous adaptation of modulation level and transmission power in a multi-cell OFDM network. We study the impact of those parameters on cochannel interference and channel reuse and present two classes of centralized heuristic algorithms to perform the allocation. Next, we focus on a single-cell multi-user system with modulation control and study the problem of subcarrier assignment to users subject to time resource constraints.; In the sequel, we study the impact of smart, antennas and Space Division Multiple Access (SDMA) on MAC layer channel allocation for a single-cell multi-user system. Our approach encompasses multiple access schemes with orthogonal channels, such as OFDM. We propose meaningful heuristic algorithms to jointly forth beams from corresponding transceivers and assign subcarriers and transceivers to users, such that the total achievable system rate is increased. (Abstract shortened by UMI.)...