Low-rate convolutionally encoded time-hopping spread spectrum multiple access systems

We propose to use a practical low rate error-correcting code in a time-hopping spread spectrum multiple access system employing a binary PPM signaling. To this end, superorthogonal codes, which are near optimal and have relatively low implementation complexity, are considered. The performance analysis shows that the proposed coded scheme outperforms the uncoded scheme significantly, or more importantly, at a given bit error rate the proposed scheme increases the number of users by a factor which is logarithmic in the number of pulses used in a time-hopping spread spectrum system.