WiMAX System Level Simulation Investigation

WiMAX is one of the most promising broadband access techniques in communication industry.Under conditions of limited power and bandwidth,WiMAX systems is expected to achieve high data rate,high reliability and high quality.These conflicting demands will result in the complex system design,which should be based on effective system simulation.Communication system simulation can be classified into two categories,one is the link level simulation and another is system level simulation.In general,link level simulation is ofen used for calibration,while system level simulation is conducted to compare the performance of different schemes or algorithms.In this thesis,the evaluating methodolgy and radio interface technology for WiMAX are studied.A dynamic system simulation platform,which based IEEE 802.16e standard,is established.The modules of simulation platform are designed.It includes network layout,mobile model,traffic model,power control model, interference calculation model,channel model,link adaptation with HARQ,link to system mapping,resource scheduling model and etc.For evaluating system level performance of various MIMO scheme in WiMAX systems,we proposed a novel approach to perform system level simulation,which is carried out by borrowing a link level algorithm and is based on spatial channel model (SCM).Both the single cell model and multiple cell model are investigated.The proposed SCM-based system level interface calculation approach is applied to close-loop precoding(CLPC)mode,close-loop beamforming(CLBF)mode and open-loop spatial multiplexing(OLSM)mode.Under conditions of the Proportional Fair scheduling algorithm,the above-mentioned various MIMO modes are simulated in the proposed dynamic simulation platform.A series of system level metrics are considered in the simulation. It includes cell average throughput,user average throughput,5%-tile user average throughput,spectral efficiency,CDF of user throughput,Histogram of MCS. Simulation results exhibits that the proposed approach can truly and accurately reflect the performance of system.