| Frequency reuse factor of one for the network is supported by IEEE 802.16e system, i.e., all cells/sectors operate on the same frequency channel to maximize spectral efficiency. However, cochannel interference (CCI) in frequency reuse one deployment can cause severe communication outage, particularly along the inter cell and sector edges. Therefore, it is necessary and practical to maximize the spectral efficiency while mitigating the CCI for IEEE 802.16e system.In this thesis, through the study of the principle of IEEE 802.16e standard, the CCI of the system has been simulated from system level. Two techniques, fractional frequency reuse and adaptive antenna system beam forming, have been applied to IEEE 802.16e system to mitigate CCI in the downlink. The author's main research work and contributions are as follows:1. A simulation modeling scheme is proposed from system level for IEEE 802.16e system, which can evaluate the performance of the system in downlink or uplink, in several networks and in different environments. Based on the simulation modeling scheme, this thesis analyzes and simulates the effect of CCI in the downlink of the system in three different networks.2. Fractional frequency reuse (FFR) is adopted in frequency reuse one deployment to mitigate CCI in the downlink of IEEE 802.16e system and a simulation scheme is proposed. Simulation results indicate that the CCI can be mitigated and communication performance be improved by FFR technique especially for users along the inter cell and sector edges. And throughput and spectral efficiency for users along the inter cell and sector edges can both be doubled.3. Adaptive antenna system (AAS) beam-forming is employed in frequency reuse one deployment to reduce the CCI in the downlink of IEEE 802.16e system. Simulation results demonstrate that the CCI can be mitigated and system performance such as throughput and spectral efficiency can be greatly improved by AAS beam forming. |
PDF Full Text Request