Radio resource management for next generation mobile communication systems.

Multi-hop and multi-carrier communication techniques have attracted enormous interest from both industry and academia recently, and have been envisioned very promising for the next generation mobile systems to fulfil their ambitious coverage and capacity goals. In comparison to conventional mobile networks, the radio resource management in the context of multi-hop and multi-carrier communications is generally much more complicated, due to the facts that extra components have to be introduced, and strong inter-dependency is envisioned between these components and the rest of the allocation function. The radio resource management is crucial to ensuring the benefits of multi-hop and multi-carrier transmissions, and hence warrants careful investigations. Nevertheless, it has not yet been fully explored in the literature. In our work, firstly, the radio resource allocation for single-carrier Multi-hop Cellular Networks (MCNs) is investigated. The throughput-maximization problem is formulated mathematically and proven to be NP (Non-deterministic Polynomial)-hard. Considering the prohibitive complexity of finding the optimal solution for such an NP-hard problem, we propose an efficient heuristic algorithm, named Integrated Radio Resource Allocation (IRRA), to find sub-optimal solutions. To prove the effectiveness of the proposed IRRA algorithm, a case study was carried out based on HSUPA (High Speed Uplink Packet Access) with fixed relay stations. The IRRA is evaluated through system level simulations, and compared with two other cases: 1) non-relaying, 2) relaying with a benchmark approach. The results show that the proposed algorithm can ensure significant gains in terms of cell throughput. Following the above studies, the radio resource allocation problem for OFDMA (Orthogonal Frequency Division Multiple Access)-based single-hop systems is studied. The constrained throughput-maximization radio resource allocation problem is formulated and linearized. Its NP-hardness proof is then given by reducing the problem into a classical NP-hard problem, namely Multiple Choice Knapsack Problem (MCKP). A novel mathematical analysis on the problem is then earned out based on its similarity to the MCKP, and an efficient heuristic algorithm, named Integrated Sub-carrier, Bit, and Power Allocation (ISBPA), is proposed to find sub-optimal solutions for it. The proposed algorithm is evaluated through system level simulations and compared to benchmark algorithms. The results show that the proposed ISBPA algorithm can ensure considerable gains in terms of cell throughput and user satisfaction ratio. Finally, the studies in the above two steps are merged and further developed into a complete radio resource allocation algorithm for OFDMA-based MCNs. Evaluation results show significant gains in terms of cell throughput and user satisfaction ratio compared to benchmark algorithms