Reasearch On Lte Radio Resource Scheduling Algorithm And NS-3Simulation Platform

With the rapid development of wireless applications, radio communication system shows the trend of broadband and mobility architecture. As a result, fourth generation mobile communication is developing rapidly. Long Term Evolution (LTE) project is developed on the basis of The3rd Generation Telecommunication (3G). It improves the3G air interface techniques. LTE can achieve higher spectrum efficiency, smaller latency and higher data rate. What’s more, it can better meet the Quality of Service (QoS) requirement of multiple services.LTE put forward a series of leading technologies. One of the important changes is optimizing the heterogeneous network. On the base of traditional macrocell, it mixes different kinds of Low Power Nodes (LPN)-based cells, including home eNB, micro eNB, pico eNB, relay and DAS. It can significantly improve the system coverage and capacity, meanwhile guarantee the fairness between users. But it also brings challenge for research and practical application. Traditional scheduling algorithms are mainly based on macrocells and without considering the unfairness that resource allocation might bring when macrocells and LPN coexist. And the intensive cell coverage may bring interference and it’s an important problem to be solved.In this paper, the research achievement of others is investigated and analyzed. Considering the characteristics of LTE two-tier architecture, an improved exponent proportional fair algorithm is proposed, which combines the interference coordination strategy and adaptive resource reservation. Then the performance of the proposed algorithm is verified. What’s more, a LTE system-level simulation platform based on Network Simulator3(NS-3) is constructed. And the Radio Link Control (RLC) function as well as the channel model are modified. The main work is summarized below:Firstly, the LTE system architecture and resource scheduling in LTE system are overviewed. Then the influence factors and practical restrictions of LTE resource scheduling are concluded. According to the consideration of channel and QoS, different kinds of resource scheduling algorithms are classified. What’s more, the potential problems of resource scheduling under multi-tier architecture are summarized.An improved exponent proportional fair algorithm is proposed. Aimed at the macrocell-femtocell architecture of LTE system, the dualstrip scene is chosen. Then the inter-tier and intra-tier interference coordination strategy is designed. Adaptive resource partition algorithms which based on time-domain and frequency-domain are also proposed. It can guarantee the fairness of macrocell users. Finally, the resource scheduling algorithm considering different service flows is proposed. It can distinguish priorities of different flows. The simulation result shows that the proposed algorithm can achieve better throughput when compared with traditional algorithms. At the same time, it can improve the QoS performance and guarantee the fairness of users.A LTE system-level simulation platform using NS-3is built. Then it is improved on the basis of the original function of multiple layers. What’s more, to deal with the practical channel condition, the RLC layer is modified and the packet retransmission function is added. It can reduce the error rate and packet loss rate. Then the whole channel model of the platform according to the relative protocols and scenario is constructed. The large-scale fading model is modified and the small-scale fading model is added. So it improves the simulation of radio transmission environment.