Conserve energy through multiple-packets transmission in heterogeneous mobile ad hoc networks

Energy condensation is a crucial issue in mobile ad hoc networks (MANETs). In our previous work, we have proposed a device-energy-load aware relaying framework (DELAR) (2004) that can effectively utilize some powerful nodes (P-nodes) to conserve energy for other common nodes (B-nodes) and in turn prolong the network lifetime. DELAR is a joint design of power control, routing, and scheduling. Moreover, in this framework, an asymmetric MAC (A-MAC) is adopted to support reliable communications on unidirectional links caused by asymmetric transmission power between the involved transmitter and receiver. Grounded on this DELAR framework which emphasizes the interaction between the MAC layer and the network layer, in this paper we further take into account the physical layer and propose a multiple-packets transmission scheme which is jointly operated with hierarchical modulation to further improve the energy efficiency and shorten the packet delay. The basic idea is to enable such P-nodes to transmit multiple packets towards different receivers in one transmission, and this transmission is implemented with hierarchical modulation to ensure sufficient SNR at all the receivers to demodulate their corresponding packets. Simulation results validate the effectiveness and efficiency of this multiple-packets transmission scheme. It can further improve the energy efficiency and greatly shorten the packet delay