Scheduled channel access using geographical classification

Abstract

Abstract-Geographical Classification Multiple Access (GCMA) is introduced for scheduled channel access in large wireless networks. GCMA uses the geo-spatial coordinates of nodes, together with their transmission and interference ranges, to define collision-free transmission schedules using deterministic distributed algorithms. These algorithms require each node to know only the geo-spatial coordinates of its immediate neighbors to derive correct transmission schedules, even in the presence of hidden terminals. The transmission frames in GCMA consist of the minimum number of time slots needed to avoid multiple access interference, given the transmission and interference ranges of the nodes. GCMA is compared against representative examples of alternative approaches to medium access control; the results of the simulation experiments show that GCMA attains higher packet-delivery ratio and better goodput with end-to-end delay comparable to the other protocols.

An Adaptive Tree Algorithm to Approach Collision-Free Transmission in Slotted ALOHA

“…Many shcedule-based MAC protocols have been proposed in the past in which distributed algorithms are used assuming transmission frames consisting of a fixed number of time slots such that nodes select time slots in a way that eliminates multiple-access interference. The algorithms that have been proposed in this context include distributed elections of time slots for broadcast or unicast transmissions [2,3,16,19], and the reservation of time slots based on voting and signaling similar to collision avoidance handshakes [23][24][25].…”

“…Some approaches allow the use of variable-length transmission frames by using lexicographic ordering of the identifiers of transmitting nodes, geographical or virtual coordinates related to the connectivity of nodes [8,9,16], or a common tree of periodic schedules of variable periods that are powers of two [13].…”