Optimization Of Radio Resource Management For Next Generation Mobile Communication System

In order to meet the growing communication requirements, the demands of next generation mobile communication system have been increased significantly, including high data rate, low network latency and so on. Represented by 3GPP long term evolution (LTE), key technologies such as OFDM and MIMO are applied to increase spectrum efficiency and system throughput. Meanwhile, flat network architecture is applied to reduce latency of user plane and control plane. However, the application of these technologies is accompanied by dimensions increase and difficulties in radio resource management. The optimization of radio resource management plays an important part in performance of these technologies.This thesis investigated optimization of radio resource management for next generation mobile communication system, applied ant colony optimization of swarm intelligence theory and opportunity cost of game theory to resource allocation and scheduling, inter-cell interference coordination and handover strategy, on purpose of optimization of resource to increase efficiency of resource and satisfaction of users.Resource allocation in multiuser OFDM system is investigated in the first part. Multiuser OFDM system can apply multiuser diversity to increase system throughput, attracting more and more attention. However, resource allocation in this system, i.e. subcarrier, bit and power allocation, is a combinatorial optimization problem, difficult to obtain optimal solution in polynomial time. Ant colony optimization is a viable approach for combinatorial optimization problems. This thesis has applied ant colony optimization to resource allocation in multiuser OFDM system and mapped ants'search for food to resource allocation in communication system. System model, algorithm process as well as parameter definition have been designed, utilizing probability search and iterative improvement of ant colony optimization to improve qualities of solutions and maximize resource efficiency.Inter-cell interference coordination is investigated in the second part. OFDM technology is applied to improve spectrum efficiency. However, it also brings serious inter-cell interference. Soft frequency reuse or fractional frequency reuse strategies are main researches for inter-cell interference coordination, in which employment of resources in cell edge is given some restrictions to reduce interference. Nevertheless, it also reduces spectrum efficiency, which is very valuable in communication system. In order to improve cell edge performance without reducing spectrum efficiency, ant colony optimization is applied in resource allocation to improve cell edge performance and reduce inter-cell interference. Since there is no restriction in resource employment, the frequency reuse factor keeps 1 and there is no decreasing in spectrum efficiency. System model, algorithm process and parameter definition are designed, resulting in throughput improvement of cell edge users and high spectrum efficiency of system.The third part investigates handover strategy. At present the relation of system and users is non-cooperative in traditional handover strategy. Users tend to handover to the best cell without consideration of influences to system, resource and other users. Meanwhile, the introduction of micro cell, pico cell as well as femtocell leads to frequent handover and load congestion. In response to these issues, opportunity cost of game theory is investigated in this thesis. Considering both system and users'resource utility, the opportunity cost makes system and users select each other rationally, leading to resource optimization in handover strategy. The introduction of opportunity cost makes system and users consider system utility, traffic load and channel quality information of users simultaneously, significantly enhancing system throughput, reducing unnecessary handover times and drop rate, as well as balancing traffic load, which leads to a win-win situation.