MPPM system for indoor wireless optical communications with angle-diversity detection

In this paper, an infrared wireless communication system based on Multiple Pulse Position Modulation (MPPM) employing angle-diversity detection is studied via simulation. The system can also be easily adapted for Visible Light Communications. MPPM is proposed as a modulation method to improve bandwidth efficiency in PPM. The system designed allows for comparing the performance based on the computation of the bit error rate (BER) as a function of the SNR for different MPPM and PPM modulation schemes employing angle-diversity detection. In this paper, two of the three ways to achieve angle-diversity detection are studied: conventional and sectored receivers. The results show a significant enhancement when angle-diversity receivers are employed, with the sectored receiver offering the highest performance. Furthermore, the results show that PPM offers a good performance for lower bit rates, though the BER increases rapidly when the bit rate is increased, even when angle-diversity receivers are used. MPPM proves to be more bandwidth efficient than PPM, since it allows to use a wider pulse for transmission of the same number of information bits per symbol.