Multiple Access: Sharing from Afar

Summary

In a vehicle transportation system, a segment of a highway is shared among multiple vehicles. A multiplexer's controller schedules the transmission of its local messages for across a shared communications medium. The access of distributed busy clients to the shared system is regulated either by using a central controller or by employing a distributed scheduling algorithm. Channel resources can be shared across multiple dimensions that include time, frequency, code and space, and their hybrids. Time slots and time frames are established, declared, and recognized by the sharing stations. Different stations can be allocated different numbers of time slots in a time frame. Under a Frequency Division Multiple Access (FDMA) scheme, each station sharing the medium is allocated a separate frequency band. In sharing a medium by a high number of stations, an FDMA system would have to assign a large number of finely tuned frequency bands.