Group-based two-hop relay with redundancy in MANETs

Two-hop relay is a class of attractive routing protocols for mobile ad hoc networks (MANETs) due to its efficiency and simplicity. This paper extends the conventional two-hop relay and proposes a more general group-based two-hop relay algorithm with redundancy. In such an algorithm with redundancy ƒ and group size g (2HR-(ƒ, g) for short), each packet is delivered to at most ƒ distinct relay nodes and can be accepted by its destination if it is among the group of g packets the destination is currently requesting. The 2HR-(ƒ, g) covers the available two-hop relay protocols as special cases, like the in-order protocols (ƒ ≥ 1, g = 1), the out-of-order protocols with redundancy (ƒ > 1, g = ∞) or without redundancy (ƒ = 1, g = ∞), and it enables a more flexible control of packet delivery process to be made in the challenging MANET environment. A general theoretical framework is further developed to explore how the control parameters ƒ and g affect the expected packet delivery delay in an 2HR-(ƒ, g) MANET, where the important medium contention, interference and traffic contention issues are carefully incorporated into the analysis. Finally, extensive simulation and theoretical results are provided to demonstrate the efficiency of the 2HR-(ƒ, g) scheme and the corresponding theoretical framework.