Study On Downlink Wireless Resource Management Technology In LTE Private Network System

Private network mobile communication system is private wireless communication system, which is designed to meet the needs of industry dispatching and industrial applications. The system mainly processes emergency events such as fires, earthquakes, etc. With the rapid development of wireless mobile communication technology, demands of the system for broadband multimedia services are increasingly significant, process industry personnel in the dispatching application of the private network communication system, not only have the requirement of the "be heard", also "be visible ", which promote the development of private network communication system to the trend of broadband data and diversified traffic. Traditional UMTS or HSPA system can not meet the requirements of the private network systems, LTE as the evolution technology of 3G, can be capable of transmitting high-speed multimedia services of multi-users using OFDM and MIMO technology. So the private mobile communication based on LTE should be adopted.In the wireless mobile communication system, it is difficult to meet QoS of different user due to the limited wireless resources, time-varying wireless channel and users’competition for radio resources; reasonable radio resource management techniques should be adopted. So this paper focuses on the downlink radio resource management technique in the private network based on LTE.First of all, this paper describes the development and characteristics of private network communication system, and explains the technical foundation of LTE public network, including public network system architecture, MAC structure, time and frequency resource structure, scheduling policies, QoS bearer and the key technology used in the LTE public system.Then, the paper focuses on traditional scheduling algorithms in LTE system, simulations of these algorithms are carried on Matlab platform and some performance analyses of algorithms are made. On the basis of traditional algorithms’analysis, problem of throughout performance’s upper bound is analyzed and a sub-optimal resource allocation scheme is proposed. The problem can be formulated into integer programming problem, which is converted to the problem with Lagrange multipliers using Lagrangian Relaxation, then sub gradient method is used to find the suboptimal solution to the problem. The simulations carried on Matlab platform show that the solution can improve the system throughout significantly.Finally, this paper proposes a combined scheduling and resource allocation algorithm to reduce downlink traffic transmission delay in LTE private network system. The algorithm takes into account the transmission delay and the channel status of different user, computes users’scheduling priority dynamically, calculates the number of radio resource blocks of each user, and then assigns the calculated resources to users in the order of the users’priority. Simulation results show that the algorithm can reduce the traffic transmission delay in some extent, while improving system throughput which can meet the needs of system and users’ traffic.