a time division multiple access communication system has a plurality of geographically separated stations including a first group of stations , each of which can communicate with any other station in the first group through a first transponder in a predetermined portion of a tdma frame , and a second group of stations , each of which can communicate with any other station in the second group through a second transponder in a predetermined portion of a tdma frame associated with the second transponder . the tdma frames of the first and second transponders are synchronized and inter - group traffic , i . e ., communications between a station in the first group and a station in the second group , takes place in another predetermined portion of each of the frames which is exclusive of the predetermined portion of both frames used for intra - group traffic . transponder hopping is employed without requiring needless duplication of terminal equipment and , at the same time , assuring non - overlapping transmissions through the same transponder . the stations transmit in a multiple channel per burst format with fully variable demand assignment . the invention is a control method and apparatus for providing a control channel for ascertaining the per - station intra - group and inter - group traffic requirements , allotting each station the necessary burst position and duration , and synchronizing burst length changes and movement of a station &# 39 ; s bursts to insure non - interference with transmission of other stations .