Affine-based time-scale ultra wideband wireless channel simulator for time-varying communication environment

Abstract

Wireless communication systems require reliable wireless link to provide high quality services for all subscribers around the world. This can be ensured by using a combination of different techniques and technologies whose performance depend on wireless channel. Therefore, an appropriate channel model based on affine approach needs to be developed to describe its performance, availability, and wide range assessments in term of Ultra Wideband (UWB) propagation characteristics. In order to develop a future communication system, knowing the channel behaviour is important to seamlessly integrate many different communication systems and enhance services to users. In a typical laboratory environment, knowledge of channel behaviour is obtained from channel simulators which are designed to mimic the physical channel. The Fourier-based channel eigenstructure employed in designing most conventional simulators and their applications for UWB channels are limited due to wider bandwidth. Therefore, by considering affine-based time-scale operator, a discrete channel model is developed. The UWB channel simulator is developed based on affine time-scale channel model. The model and simulator are developed by using LabVIEW® software platform. Then, the developed UWB simulator is implemented on Field-Programmable Gate Array (FPGA) hardware platform. This UWB channel simulator is designed for short distance, at range (0-30m) with the frequency range at (3.1-5.3GHz). This simulator is also be simulated for different channel parameters such as different operating environment for indoor and/or outdoor to observe its performance. The channel effect toward signals is obtained by analyzing the simulation and the measurement results of the root means square (RMS) delay spread. The received signal, power delay profile and RMS delay spread are presented to evaluate the UWB channel simulator performance. The RMS delay spread for non line-of-sight (NLOS) is obtained around 1.8843ns and LOS is around 1.6894ns. It shows that RMS delay spread for NLOS is high than the LOS. The maximum RMS delay spread for indoor and outdoor environments are 4ns and 7ns, respectively. The difference in the RMS delay spreads describes different propagation phenomenon operating environment. In addition, these numerical values indicate the UWB channel simulator performance for small-scale fading. Affine shows a flexible approach in analyzing the non-stationary environment compared to Fourier analysis and Fourier analysis needs to count every frequency change and may increase system complexity. The results are validated based on measurement and comparison from previous work. Finally, the UWB channel simulator has been implemented into FPGA device as a UWB channel simulator-hardware platform.