WiSim - A software simulation testbed for mobile WiMAX

Next generation wireless system designing has the wide array of choices for advanced signal processing algorithms and a variety of operating environments. The scope and complexity of the IEEE 802.16 standard creates challenges for designers of standard-compliant components. Model based design addresses these challenges by placing a system model at the center of the development process from requirements capture to implementation and testing. This paper describes a software based testbed (WiSim) which simulates WiMAX Radio Air Interface both at link level and system level. The WiSim testbed is a tool to evaluate various design options and trade-offs in different system and environment scenarios. WiSim simulates both MAC layer and three PHY's layers of WiMAX (SC PHY, OFDM PHY, OFDMA) PHY) based on IEEE 802.16-e standard. The simulator supports all the optional features like MIMO, Block Turbo coding, Space Time coding, Convolutional Turbo coding as mentioned in the standards. So a fair performance evaluation can be done between the mandatory and optional features. System level simulation parameters like Cell layout, BS and SS antenna parameters and Fast HARQ are considered in the simulator. The simulator supports SUI fixed broadband wireless channel model, ITU channel model and 3GPP MIMO channel model and a user can modify any one of the channel model parameter. As the Standard does not talk much about the receiver design, various receiver algorithms for PAPR reduction, Time and frequency synchronization, Carrier frequency offset and channel estimation are identified vis-A-vis to WiMAX and are implemented in Simulator.