Research On Radio Resources Management About Broadcast Multicast In TD-LTE System

In the face of the contradiction between the demand of growing broadcast multicast service and shortage of wireless resources, how to efficiently manage the wireless resource and achieve high-quality broadcast multicast service are the current and future problems. In this paper, radio resource management about broadcast multicast in TD-LTE system is the research project, and it mainly focus on the research of transmission mode selection and resource scheduling of Multimedia Broadcast Multicast Service(MBMS) which associated with wireless resource management in the Multicast Broadcast Single Frequency Network(MBSFN).In view of the problem that resource allocation of Single Frequency Network transmission mode(SFN) is conditioned by signal poor quality users, a novel mixed transmission mode(MIX) is put forward based on the existing Point-to-Point(PTP) and SFN transmission mode. PTP and SFN are incorporated in MIX. In MIX mode, PTP transmission mode will be adopted to provide MBMS business for poorer signal users, and the rest users will still receive the MBMS business in SFN transmission mode. In order to maximize the frequency spectrum efficiency, a novel transmission mode selection algorithm which based on MIX transmission mode is proposesd. In this selection algorithm, let spectral efficiency as the optimization goal, and select the transmission mode for MBMS business among PTP, SFN and MIX. In order to determine the state of MIX and reduce the algorithm complexity, a fast-select algorithm based on the greedy thought is designed to determine the ways in which users receive the MBMS business. In order to further reduce the complexity of the algorithm, the fitting function of the fast-selection algorithm is constructed to ascertain MIX transmission mode. The simulation result shows MIX results in higher spectral efficiency than SFN transmission mode and the transmission mode selection algorithm considers MIX can economize more wireless resources than traditional algorithm once there are users whose signals are subpar. In order to avoid the effect of overloading cell on the overall resource allocation in MBSFN, a novel transmission mode selection algorithm which based on MIX transmission mode targeting with load balancing is proposed. In this algorithm, select the transmission mode for MBMS business between PTP, SFN and MIX to minimize the maximum load cell bandwidth. The simulation result shows the transmission mode selection algorithm considers MIX can better reduce the resource requirements of the highest load cell than traditional algorithm once there are users whose signals are subpar, and the cell load within the MBSFN can get balanced.In view of the problem that the time delay performances of existing resource scheduling algorithms are affected by the algorithm design, a novel scheduling algorithm based on hierarchy decision to protect delay performance for delay-sensitive MBMS service is put forword. The scheduling level in the algorithm is divided according to time delay emergency level and the cache data with same time delay emergency level. In the scheduling algorithm, different scheduling levels have different priorities, and the business data with same level will get scheduled according to traditional EXP/PF algorithm. The simulation result shows that the scheduling algorithm based on hierarchy decision to protect delay performance can get lower average waiting delay and packet loss rate while comparing with traditional EXP / PF scheduling algorithm, so it can get better latency performance.