Cyclic time hopping in time division multiple access communication system

Abstract

A technique for cyclic time hopping in a multiple access communication system, wherein each time frame of a TDMA system is divided into multiple time slots. A plurality of user stations, one for each time slot, communicate with a base station. Each user station regularly varies its relative time slot position in a pseudo-random pattern. Orthogonal time hopping patterns are determined from a root pattern according to a predetermined equation or relationship. The effect of transmitting bursts in a pseudo-random pattern is to break up the otherwise strict periodicity of TDMA bursts, and to produce a more noiselike spectrum for switching transients, thereby reducing the level of interfering spectral components from a TDMA transmission source. In some embodiments, the time hopping pattern may be restricted to only odd or even time slots. In such embodiments, a dead time slot may be declared periodically so as to increase the apparent randomness of the user station transmission patterns. In a preferred embodiment, spread spectrum communication is employed for base station and user station transmissions.