Resource Allocation And Cooperative Optimization In Lte Network

LTE (Long Term Evolution) has become one of the mainstream communication technologies in the world. LTE technical specifications improve rapidly, but there are many imperfect parts which may result in poor LTE system performance. Thus it is significant to find out the weakness of LTE protocol and improve it based on the protocol analysis, simulation and test of the existing LTE technical specifications.Based on the actual needs, this thesis firstly analyzes the existing LTE technical specifications, including S1, X2and Uu interfaces, and then the protocol stack, functions, and signaling. The above analysis has provided a theoretical foundation to build a simulation test system which can simulate and test the existing technical specifications of LTE interfaces. Besides, the thesis analyzes the TTCN3and ASN.1programming language which provide another programming environment for LTE protocol testing.Secondly, this thesis has built the LTE interface signalling system simulation and test platform based on both TTCN3and C/C++programming language. The TTCN3version has tested the signaling processes of LTE interfaces using a method of the simulation test cases. The C/C++version has finished a MME simulator which is a network element simulator of LTE system. The C/C++version can support an UE to attach the LTE network, communicate with other equipment, detach the LTE network and other operations. This platform has tested and verified the existing LTE signaling mechanism. The test results show that the communication path in the current LTE networks has not been optimized, especially for two UEs attached to the same eNB need to communicate with each other. Under this condition, signaling and data also must be transmitted to MME/S-GW. This problem will lead to the local traffic data’s repeat transmission between the eNB and MME/S-GW, namely unnecessary overhead of the LTE backhaul network.With the promotion of new mobile broadband services and next-generation mobile standard, bandwidth requirements increase rapidly. Then great pressure will be brought to backhaul networks. In order to solve the problems found in the simulation to LTE protocol and alleviate the bandwidth pressure on the backhaul network, this thesis optimizes the LTE network and devises a new transmission mechanism for local traffic data of LTE network. This mechanism makes use of a method named local forwarding in the LTE traditional network. In the local forwarding method, data transmitted between two UEs attached to the same eNB is forwarded without necessarily being sent to the MME/S-GW. Thereby the stress of bandwidth need for backhaul networks can be alleviated and bandwidth usage efficiency for backhaul networks can be raised. After the simulation to this mechanism, with the increasing proportion of local traffic, this mechanism can reduce the blocking rate of LTE backhaul network with the same total traffic. Then the LTE system performance can be improved. For the optimization mechanism this thesis also devises a new signaling mechanism which is compatible to current LTE technical specification and may improve the LTE protocol effectively.