MERLIN: Cross-layer
Integration of MAC and Routing for Low Duty-Cycle Sensor Networks
Antonio G. Ruzzelli, G.M.P O'Hare, M.J. O'Grady, and R. Jurdak Abstract
Sensor network MAC protocols typically sacrifice packet latency to achieve
energy efficiency. Such delays may well
increase due to routing protocol operation. Therefore, quantifying the
end-to-end delay and energy consumption when low duty cycle MAC and routing
protocols are jointly used, is of particular interest. In this paper, we
present a comprehensive evaluation of MERLIN (MAC and Efficient Routing
integrated with support for localization), a cross-layer protocol that
integrates MAC and routing features. In
contrast to many sensor network protocols, it employs a multicast
upstream and multicast downstream approach to relaying packets to and from the
gateway. Simultaneous reception and transmission errors are notified by
asynchronous burst ACK and negative burst ACK messages. A division of the
network into timezones, together with an appropriate scheduling policy, enables
the routing of packets to the closest gateway. An evaluation of MERLIN has been
conducted through simulation, against both the SMAC and the ESR routing
protocols, which is an improved version of the DSR algorithm. The results illustrate
how both SMAC and ESR, jointly used in low duty cycle scenarios, cause
extremely high end-to-end delays. MERLIN, as an integrated approach, notably
reduces the latency, resulting in nodes that can operate in a very low duty
cycle, yielding a significant extension in network lifetime.
To appear in Special Issue of Elsevier Ad Hoc Networks Journal. December 2007. (in press)