Performance analysis of indoor infrared wireless systems using PPM CDMA with linealizer with dead-zone and PPM CDMA with hard-limiter on diffuse channels

Abstract

We analyze the performance of indoor infrared wireless systems using pulse position modulation (PPM) code-division multiple-access (CDMA) on diffuse channels by taking the effects of intersymbol interference (ISI) of more than ten chips into account. Then we analyze the system with a hard-limiter (HL) and the system with a linealizer with dead-zone (LDZ) on diffuse channels. We evaluate the performance of the system with HL, the system with LDZ, and that of the system with the decision-feedback equalizer (DFE) on diffuse channels. We show that the bit error rate (BER) performance of the system using PPM CDMA is worse than that of the system using on-off keying (OOK) CDMA on diffuse channels. We also show that the BER performance of the system with the HL and that of the system with the LDZ are both better than that of the unequalized system on diffuse channels. We also show that the BER performance of the system with HL is almost identical to that of the system with the DFE on diffuse channels. We further show that when the desired code sequence is (0,1,5) and the effects of ISI is large, the BER performance of the system with the LDZ is superior to that of the system with the HL. However, in the average BER performance over each code sequence, the system with the HL is better.