Experimental Implementation of Adaptive CFAR Multipath Detection for Wideband Communication Systems

Multipath detection is very important for the proper operation of wideband communication systems. Conventional detectors using constant threshold result in suboptimal performance since they either fail to detect a multipath component or provide a wrong path to the receiver. In this paper, two adaptive constant false alarm rate (CFAR) multipath detectors are proposed: cell-averaging CA-CFAR and order-statistics OS-CFAR. An experimental indoor wideband communication system operating at the 5 GHz range has been implemented to collect real data for use by the proposed CFAR detectors. Details of the implemented system and experimental results are presented in this paper. It is observed that the OS-CFAR detector outperforms the CA-CFAR in terms of detection capability.

I. Introduction

In wideband communication systems, such as Direct Sequence Spread Spectrum (DS-SS), the spectrum of the signal is spread over a large bandwidth. Typically, the signal bandwidth is much greater than the coherence bandwidth of the channel which results in frequency selective fading. In other words, the signal propagates over distinct multipath components that undergo independent fading. It is therefore important, for the proper operation of the receiver, to collect the energy distributed over these multipath signals. Hence, an efficient multipath detection scheme is needed.