CHAPTER 9 - Multiple-Access Procedures

Abstract

This chapter discusses number of multiple-access procedure choices, such as fixed time division multiple access, asynchronous time division multiple access, adaptive time division multiple access, frame address time division multiple access, and reservation time division multiple access. Multiple access procedures control software programs stored in the terminal's memory, which provide the means of sharing the transmission facility. The task of the multiple-access procedure is to have the channel shared efficiently among the users (terminals) rather than to divide the channel into fixed portions. This can best be done only by orderly controlling the traffic in the channel. The traffic usually acts in a random bursting nature with the number of messages originating from the terminals in uneven distribution loads. One solution then is to employ a number of procedures that are selected in accordance with the traffic load or to design procedures that adapt themselves as a function of the traffic load. The procedures to be chosen for a particular application should always be decided upon in accordance with the nature of the application. There is no such thing as an ideal procedure, as each procedure has an unavoidable price of delay, collision, waste or overhead.