Rate adaptive transmission scheme using punctured convolutional codes in a fixed channel reuse strategy with PPM CDMA

We propose a rate adaptive transmission scheme using punctured convolutional codes in a fixed channel reuse strategy with pulse position modulation (PPM) code division multiple access (CDMA) for indoor infrared wireless communications. The proposed system varies the code rate of the punctured convolutional codes, that is, the bit rate adaptively depending on the channel conditions, and can achieve the required bit error rate in all space in a cell. We consider nondirected line-of-sight (LOS) downlinks in a channel reuse strategy with hexagonal cells and a reuse factor of three. We show that the proposed system can realize communications in all space in a cell at the expense of bit rate.