We analyze the performance of trellis-coded pulse-position modulation with block decision-feedback equalization (BDFE) and parallel decision-feedback decoding (PDFD) on indoor, wireless infrared channels. We show that the reduced complexities of BDFE and PDFD as compared to maximum-likelihood sequence detection allow for better codes whose increased coding gain more than compensates for the penalty due to suboptimal detection. We quantify these net gains in performance over a range of dispersive channels, indicating where BDFE and PDFD provide the best performance. Finally, we present Monte Carlo simulation results to verify our analysis.

We report a non-line-of-sight optical link for short-range, indoor data transmission at 25 Mb/s. The optical link uses a ceiling-directed beam and a wide-field-of-view receiver. The system uses 4-pulse-position modulation (4-PPM) with scalar decision-feedback equalization (SDFE), achieving low bit-error rates with a range of two meters in the presence of background light and multipath-induced intersymbol interference. We observe that the gain in electrical SNR efficiency from equalization is about 0.5 dB larger than theory, which we attribute to timing-offset errors in the unequalized system. We verify that the near-DC noise caused by electronic ballast-driven fluorescent lamps has a negligible impact on the system performance.

We analyze the performance of trellis-coded pulse-position modulation (PPM) on indoor, wireless infrared channels. We show that maximum-likelihood sequence detection (MLSD) of trellis-coded PPM is very effective in mitigating the multipath dispersion on such channels. We present code search results for high constraint-length, rate-2/3, 8-PPM and rate-3/4, 16-PPM codes. We provide bit-error rate curves and intersymbol interference power-penalties for MLSD of PPM with these codes, evaluated on ceiling-bounce channel models with delay spread per bit duration ratios of 0.01-0.3. Finally, we present Monte Carlo simulation results to verify our analysis.

We analyze the performance of trellis-coded pulse-position modulation (PPM) on indoor, wireless infrared channels. We show that maximum-likelihood sequence detection (MLSD) of trellis-coded PPM is very effective in mitigating the multipath dispersion on such channels. We present code search results for high constraint-length, rate-2/3, 8-PPM and rate-3/4, 16-PPM codes. We provide bit-error-rate curves and intersymbol interference power penalties for MLSD of PPM with these codes, evaluated on ceiling-bounce channel models with delay spread per bit duration ratios of 0.02 to 0.3. Finally, we present Monte Carlo simulation results to verify our analysis.