Infrared has abundant, unregulated bandwidth enabling rapid deployment at low cost. However, safety limits on power emission levels (IEC825), large noise due to ambient lighting, and multipath dispersion remain as hurdles in diffused indoor environments. Especially, the high-frequency periodic interference produced by fluorescent lights is a major concern. Spread spectrum techniques enable low-power operation and noise rejection, at the expense of large processing gain. In this paper, we quantify the noise received and propose an adaptive FIR filter to jointly cancel the multipath dispersion and the fluorescent light noise in an infrared CDMA system. From analytical and simulation results, the adaptive filter significantly enhances the noise rejection capability of the CDMA system and tracks well the quasistationary indoor wireless channel. Our results show tenfold improvement in the BER for a given SNR and processing gain due to the adaptive filter. The filter also performs well in the multiuser environment.

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Infrared system provides a feasible alternative to radio system for indoor wireless communication. Direct spread CDMA format is a promising candidate for infrared transmission system. In indoor systems, transmission is severely impaired by noise and interference produced by artificial light. In this thesis, the performance of the DS CDMA indoor wireless infrared system on diffuse channels is analyzed by taking the effects of inter symbol interference (ISI) and electronic ballast florescent light interference into account. Moreover, to mitigate the effects of ISI and electronic ballast florescent light interference, an adaptive filter technique is proposed for noise cancellation and equalization. This is done by considering a ceiling bounce model for the channel and electronic ballast florescent light for noise. Analytical and simulation results show 7dB improvement in SINR and 10-15 times improvement in BER.

Infrared system provides a feasible alternative to radio system for indoor wireless communication. Direct spread CDMA format is a promising candidate for infrared transmission system. In indoor systems, transmission is severely impaired by noise and interference produced by artificial light. In this thesis, the performance of the DS CDMA indoor wireless infrared system on diffuse channels is analyzed by taking the effects of inter symbol interference (ISI) and electronic ballast florescent light interference into account. Moreover, to mitigate the effects of ISI and electronic ballast florescent light interference, an adaptive filter technique is proposed for noise cancellation and equalization. This is done by considering a ceiling bounce model for the channel and electronic ballast florescent light for noise. Analytical and simulation results show 7dB improvement in SINR and 10-15 times improvement in BER.