Study On Downlink Scheduling Algorithms For Carrier Aggregation

With the development of mobile communication, system capacity and peak rate are promoted rapidly and more bandwidth is required. In order to meet of requirements of large bandwidth in LTE-Advanced system, the carrier aggregation technology has been introduced to utilize the scattered spectra flexibly. This thesis is focusing on the downlink scheduling algorithms in the LTE-Advance system based on carrier aggregation technology. The main content is organized as follows:First of all, the LTE system requirements that 3GPP proposed, the relationship between LTE and LTE-Advanced system and the technical background of the carrier aggregation technology are briefly introduced. Then, the system features and the key technologies for LTE-Advanced system are introduced. In the next section, the relative concepts and technologies of carrier aggregation are discussed, and uplink and downlink scheduling processes for LTE system and three classical scheduling algorithms are studied.The fourth part is the main point of the thesis. In the carrier aggregation scenario in which different component carriers have consistent beam direction and the same coverage, an improved scheduling algorithm is developed. The simulation results show that the improved scheduling algorithm can guarantee system throughput and ensure high system fairness and low system delay at the same time. In the carrier aggregation scenario in which different component carriers have consistent beam direction but different coverage, an improved algorithm for throughput promotion for the users on the edge of a cell is developed. The new algorithm is developed on the base of proportional fair scheduling algorithm, and a specific compensation factor for the users on the edge is introduced. The MATLAB simulation shows that the throughput of users on the edge of a cell and system fairness can be effectively promoted. Therefore, the proposed algorithm is numerically verified to be correct and effective.