Event-driven data aggregation (EDDA) scenario is widely applied in wireless sensor network (WSN) applications. In this paper, we present a MAC protocol of WSN for EDDA scenario, referred to as E-MAC. Different from other MAC protocols, E-MAC is designed upon the attributes of EDDA scenario. E-MAC classifies the nodes in EDDA scenario and divides the transportation of data packets into several stages. Through sequential wake-up, multi-hop reservation and staggering transmission, E-MAC schedules data packets from the event zone across multiple hops in the same cycle. As a CSMA based protocol, it offers favorable performance with a low energy cost in EDDA scenario. We analyzed the latency of E-MAC and RMAC [3] numerically in EDDA scenario. Besides, we evaluated E-MAC in EDDA scenario using ns-2.29 and compared it with RMAC. Results of both the analysis and the simulation state that the advantage lies in E-MAC in EDDA scenario.

This paper addresses energy conservation, a fundamental issue of paramount importance in heterogeneous mobile ad hoc networks (MANETs) consisting of powerful nodes (i.e., P-nodes) as well as normal nodes (i.e., B-nodes). By utilizing the inherent device heterogeneity, we propose a cross-layer designed Device-Energy-Load Aware Relaying framework, named DELAR, to achieve energy conservation from multiple facets, including power-aware routing, transmission scheduling and power control. In particular, we design a novel power-aware routing protocol that nicely incorporates device heterogeneity, nodal residual energy information and nodal load status to save energy. In addition, we develop a hybrid transmission scheduling scheme, which is a combination of reservation-based and contention-based medium access control schemes, to coordinate the transmissions. Moreover, the novel notion of "mini-routing" is introduced into the data link layer and an Asymmetric MAC (A-MAC) scheme is proposed to support the MAC-layer acknowledgements over unidirectional links caused by asymmetric transmission power levels between powerful nodes and normal nodes. Furthermore, we present a multi-packet transmission scheme to improve the end-to-end delay performance. Extensive simulations show that DELAR can indeed achieve energy saving while striking a good balance between energy efficiency and other network performance metrics.