Interior Wireless Channel Design and Performance Analysis

Abstract

Infrared light for indoor wireless communications has received considerable attention recently. Unfortunately infrared are more susceptible to shadowing or noise source and have stringent alignment requirements. However, a reliable communication can be made possible by the design of transceiver, which in turn depends on designer’s knowledge on the propagation properties at infrared frequency and characterized infrared channel by measurements. The objective of this work, is to setup an indoor wireless infrared communication system, based on the Line of Sight (LOS) transmission link using a laser diode as the transmitter device and a photodiode as the receiver device. The main purpose of this setup is to determine the best channel characterization for an optical wireless communication by varying the parameters such as receiver bandwidth and transmission distance. This work is divided into two parts. The first part is to design and stimulate a transimpedance amplifier receiver with bandwidth adjustment capabilities using Multisim. The stimulation results shows that by varying the designed transimpedance amplifier receiver bandwidth, produces a cutoff frequency range between 10MHz to 100MHz while the gain remains at 15dB. Optsim is used to determine the eyediagram, bit error rate and the Q factor of the optical wireless system when the transmission distance is varied. The stimulated results shows that as the distance increase, the bit error rate decreased. The second part of this work is to setup the experimental system. The experimental measurement shows that the maximum transmission distance is 4m. As the distance increased, the transmitted signal becomes distorted due to ambient noise. The measured gain at 0m is -4.8dB, compared to the stimulated gain has a difference of 19.8dB.