Grid based two transmission range strategy for MANETs

In a mobile ad hoc network (MANET), it becomes practically viable to use virtual infrastructures to improve energy efficiency. The square-based infrastructure divides the network area into squares of the same size. Fourand eight-directional forwarding are two popular forwarding methods in the square-based infrastructure. In four-directional (or eight-directional) forwarding, packets can be forwarded from a square to its four (or eight) neighboring squares. Previous research shows, to achieve the maximum energy saving, each forwarding method must choose a proper square size for the infrastructure, and each method has its advantageous directions in terms of energy saving. That indicates an adaptive strategy combining both methods will save more energy in every direction. However, it is costly for nodes to maintain two infrastructures. Instead of maintaining two infrastructures, this paper proposes to use two different power levels for transmitting packets. The low power level is used for transmission of packets to horizontal or vertical neighbors and the high power level for transmission to diagonal neighbors. The proposed two transmission range scheme has the advantages of both four- and eight-directional forwarding schemes, yet only one infrastructure needs to be maintained. The paper compares the energy efficiency between the proposed scheme and related schemes analytically and numerically. It shows that the two transmission range strategy outperforms both eight- and four-directional forwarding in terms of path optimality, network lifetime, and average node power consumption.