Rate-adaptive indoor infrared wireless communication systems using punctured convolutional codes and adaptive PPM

In this paper, we propose rate-adaptive indoor infrared wireless communication systems using punctured convolutional codes and adaptive pulse-position modulation (PPM) to achieve high bit rates under various channel conditions with reasonable transmitter power. The proposed system varies the code rate of the rate compatible punctured convolutional (RCPC) codes and the modulation order of PPM adaptively according to the channel condition. When the channel condition is good, low-order PPM and suitable code rates are selected, while high-order PPM and suitable code rates are selected when the channel condition is bad. We analyze the performance of the proposed system on hybrid line-of-sight (LOS) channels. Our results show that the proposed system can achieve high bit rates by varying the code rate of the RCPC codes and the modulation order of PPM adaptively according to the channel conditions. Moreover, our results show that the proposed system can achieve longer horizontal separation between the transmitter and the receiver than that of conventional systems with repetition codes.