Resource Management in Multi-hop Cellular Networks
Tam, Yik Hung
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In recent years, mobile communications have become affordable and popular. High cellular capacity in terms of number of users and data-rates is in need. As the available frequency spectrums for mobile communications are limited, the utilization of the radio resources to achieve high capacity without imposing high equipment cost is of utmost importance. Recently, multi-hop cellular networks (MCNs) were introduced. These networks have the potential of enhancing the cell capacity and extending the cell coverage at low extra cost. However, in a cellular network, the cell or system capacity is inversely related to the cell size. In MCNs, the cell size, the network density and topology affect the coverage of source nodes and the total demands that can be served and, thus, the system throughput. Although the cell size is an important factor, it has not been exploited for maximizing throughput. Another major issue in MCNs is the increase in packet delay because multi-hopping is involved. High packet delay affects quality of service provisioning in these networks. In this thesis, we propose the Optimal Cell Size (OCS) and the Optimal Channel Assignment (OCA) schemes to address the cell size and packet delay issues for a time division duplex (TDD) wideband code division multiple access (W-CDMA) MCN. OCS finds the optimal cell sizes to provide an optimal balance of cell capacity and coverage to maximize the system throughput, whereas OCA assigns channels optimally in order to minimize packet relaying delay. Like many optimized schemes, OCS and OCA are computationally expensive and may not be suitable for large real-time problems. Hence, we also propose heuristics for solving the problems. For the cell size problem, we propose two heuristics: Smallest Cell Size First (SCSF) and Highest Throughput Cell Size First (HTCSF). For the channel assignment problem, we propose the Minimum Slot Waiting First (MSWF) heuristic. Simulation results show that OCS achieves high throughput compared to that of conventional (single-hop) cellular networks and OCA achieves low packet delay in MCNs. Results also show that the heuristics, SCSF, HTCSF and MSWF, provide good results compared to the optimal ones provided by OCS and OCA, respectively.