Analyses of Indoor Optical Wireless Channels Based on Channel Impulse Responses

This chapter analyzes different indoor channel impulse responses and their Fourier transforms, and the frequency responses of the channels. It shows that the size of the room and the positions of transmitters and receivers have a big influence on their achievable performance. The chapter shows that line‐of‐sight (LOS) channels have better ‐3 dB bandwidth and smaller root‐mean‐square (rms) delay spread compared to NLOS channels. It explains the effects of adding furniture in a room. The conclusion is that if the receiver location is not near some furniture which is at a higher height than the receiver itself, the results obtained from analyzing an empty room can be used interchangeably without introducing too many significant errors. Lastly, signal‐to‐noise ratio (SNR) calculations are used to show that using a bare photodiode, even an avalanche photodiode (APD), will not be good enough to obtain sufficient SNR to ensure a bit‐error‐rate (BER) of 10‐6.