Collision-balancing frequency hopping in single-hop mobile ad hoc networks

Abstract

We consider a single-hop frequency hopping (FH) mobile ad hoc network (MANET). To increase throughput orthogonal FH (O-FH) with hop-synchronous hopping can be used, thereby allowing collision-free transmissions under certain circumstances. However, as the MANET grows, hopping sequences must be re-used. As a result, nodes sharing the same sequence will experience deterministic collisions while others having a unique sequence will still communicate collision-free. This results in an emph{unfair} interference situation and makes performance guarantees difficult to meet for all nodes simultaneously. In this paper, we propose a emph{collision-balancing} FH (CB-FH) scheme to overcome this drawback. The CB scheme builds on O-FH and adapts the sequence set to balance interference among the nodes. We analytically study the characteristics of the adaptive sequences and analyze the resulting interference situation at the nodes. The performance is compared to uncoordinated FH (U-FH) and O-FH. It is found that CB-FH solves the problem of unfairness present in O-FH. Compared to U-FH, CB-FH yields considerable improvements in a wide range. Practical issues are discussed.