When a limited amount of bandwidth is allocated for communication services, a system is required to accommodate as many users as possible by effectively sharing the limited bandwidth. Therefore, in the field of communications, the term multiple access could be defined as a means of allowing multiple users to simultaneously share the finite bandwidth with least possible degradation in the performance of the system.

There are several techniques how multiple accessing can be achieved. They can be mainly classified into two types based on the overall coordination needed for attaining multiple access. They are coordinated multiple access techniques and uncoordinated multiple access techniques.