Resource Allocation And Scheduling In LTE/LTE-advanced Heterogeneous Network

With the rapid growth in mobile data service flow, the existing spectrum has been unable to meet the demand of operators. Through the deployment of small cells to form a heterogeneous network is becoming an effective way to solve this problem. This kind of heterogeneous network, deployment is facing an unprecedented challenge while significantly improving the network coverage. Once small cells deployed globally in3.5GHz frequency with current macro cellular, and network in different-frequency, the reasonable resources allocation and scheduling would become a main problem for the future cellular system. In addition, the LTE small cell on/off mechanism can make full use of bandwidth resource in heterogeneous network. In this thesis, the resource allocation and scheduling based on signal traffic and mixed traffic, as well as small cell on/off mechanism in LTE/LTE-A heterogeneous network are studied.Firstly, according to the characteristics of LTE/LTE-A heterogeneous network, a new model for real-time video streaming is introduced, followed by a design of an optimized three-step resource scheduling scheme. In step Ⅰ, the number of RBs for delivering one video packet is calculated. In step Ⅱ, all the packets entering into the buffer need to be rearranged by their frame indices. Finally, in step Ⅲ, users’ priorities are determined by the QoS of video traffic. The system level simulation results show that the new scheme outperforms proportional fair (PF) algorithm in terms of frame delay and throughput. Furthermore, the system could achieve the optimal performance at a certain buffer size of35.Secondly, we design a new resource allocation and scheduling algorithm for FTP and real-time video streaming mixed traffic by considering traffic priority and user priority separately, to distinguish traffic priorities. Then users’priorities with the same types of traffic are decided. System level simulation results show that the new scheme could significantly improve FTP user and real-time video user throughput as well as video frame delay compared to PF algorithm. In order to ensure the user’s fairness, the new scheme can achieve the optimal system performance of the system when the buffer size is set to40.Finally, to make full use of bandwidth resource in LTE/LTE-A heterogeneous network, DRS with the LTE small cell on/off mechanism is measured and evaluated. By measuring DRS from small cell, UE can quickly select the optimal cell and conduct handover. Improving DRS measurement accuracy can be beneficial to small cell on/off operation and reduce the transition time. Simulation results show that CRS and CSI-RS without muting can only be measured in the very limited number of small cells, e.g. in the case of70%discovery, only the small cell with the strongest signal can be discovered. When CSI-RS with muting is considered, the DRS measurement accuracy could be dramatically improved. In the case of70%discovery, the top four strongest small cells are discovered. The best trade-off between CSI-RS SINR and CSI-RS overhead can be achieved with a reuse factor of6.