Radio Resource Management In Multi-cell OFDMA Mobile Communication Systems

Nowadays, as the development of the mobile communication technology,cell-coordination has become a key to deal with inter-cell interference and thus toachieve a better performance within the system. On the other hand, OFDMA is becomingmore and more popular due to its outstanding ability in anti-aliasing and interference coordinations. OFDMA has been widely utilized in many cutting-edge wirelesstransmission protocols like3GPP LTE (long term evolution) and WiMAX. There havebeen quite many works on the radio resource allocation within single-cell OFDMAnetworks. However, designing a high-performance resource allocation scheme in amulti-cell OFDMA network is still a very challenging work. In this thesis, we investigatethis issue from two angles: a centralized way and a distributed way.We first propose a two-step, graph-based scheme in multi-cell OFDMA resourceallocation. It is a centralized way of doing radio resource allocation. In the first step, wedivide the users into different groups so that users in the same group can share the samesub-channels. By doing this, we can coordinate the inter-cell interferences in the network.In the second step, sub-channels are allocated to the groups of users, under certainfairness rules, we can allocate the resource in an optimal way. The two steps are all doneby using tools of graph theory. By doing like this, we lowered the computing complexitywhile maintained a high system throughput.The centralized way can achieve pretty good system performance, like totalthroughput and average user rate. However, the shortages of centralized methods arepretty obvious: a CU with high computing abilities as well as high capacity channelsbetween BSs and CU are required. This is usually not easily realized. Thus, we also comeup with a distributed way of doing radio resource allocation, by using interfering list; allthe BSs can share and maintain the same interference information, thus coordinate theinter-cell interference.In this work, we propose two approaches of radio resource allocation in multi-cellOFDMA networks, from centralized and distributed angles respectively. Both of them aim at improving the system performance by coordinating interferences and utilizingeach channel’s instantaneous information. Finally, we provide simulation results to showthe privilege of our algorithms, including total throughput, average user rate, drop rate,etc., and the comparison with other existing benchmarks.