Study Of LTE-A Precoding And Resource Allocation For Relays

In order to meet the challenges of WiMax and other broadband wireless access technologies,3GPP launched the Long Term Evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) in 2004. In order to meet higher demand for mobile communications market, in 2008 LTE started to be further promoted to LTE-Advanced (LTE-A). LTE-A can support a large number of transmit antennas to 8. In the 8-antenna limited feedback system,3GPP proposed a dual-codebook precoding technique. Dual-codebook design and codebook selection are key problems to be solved. Relaying has been regarded as an effective technique to improve cell-edge performance and cell coverage. However, the deployment of simultaneous relay and base station (BS) transmission induce mutual interference within a cell. Resource allocation with fractional frequency reuse offers a simple solution to address this problem.This thesis firstly describes several key technologies of LTE-A system, and constructs a LTE-A link-level simulator. LTE-A link-level simulation platform is based LTE link-level simulator by adding MEMO mode 7-9 according to the 3GPP physical layer protocol. The simulator is made up of several functional modules including modulation, coding, precoding, channel generation, MIMO decoding, statistical results and so on. Our physical simulator supports all transmission modes of LTE-A standard.The thesis introduces dual-codebook precoding techniqueS. First, we introduce the fixed single code-book based on DFT and 3GPP R10 double codebook design method. By analyzing the advantages and dis-adbantages of the fixed codebook, we propose a differential dual-codebook design based on Grassmannian codebook. This method which takes advantage of Grassmannian codebook updates in real-time collection of dual-codebook with changing in channel variations. We also introduce two kinds of dual-codebook selec-tion methods, named joint selection and separated selection. By analyzing from the complexity, delays, and performance, separated selection algorithm shown superior to the joint selection.Subsequently the thesis focuses on the framework of LTE-A system-level simulator. LTE-A system-level simulator is based on LTE system-level simulator by adding relay based cellular network including relay network initialization, channel modeling, sheduling, L2S interface and uplink feedback. After developing the system-level simulator, this paper calibrates our system-level simulator wtih 3GPP reports. All simulation matches published industrial results well. These verifies the effectiveness of this system-level simulator.Finally, resource allocation in relay based celluar network is studied. According to the traditional cellular network resource allocation scheme, we propose a fractional frequency reused resource allocation in direc-tional relay networks. In this scheme, relay transmission link and the BS transmission link occupy the same frequency band, and reduce interference by the cross-band. Compared with omni-directional relay network, directional relay network can bring significant performance gain. We also introduce three kinds of user access strategies and the performance of the algorithm based on SINR is superior than others.