ORGMA: Reliable opportunistic routing with gradient forwarding for MANETs

For decades, numerous routing protocols have been designed to serve unicast traffic in wireless ad hoc networks. However, these routing protocols still provide limited performance in dynamic environments of mobile ad hoc networks (MANETs). In this paper, we review representative routing protocols and evaluate their performance through NS-3 simulations to identify their main weaknesses. Based on our observations, we develop a reliable and practical opportunistic routing protocol for MANETs, named as ORGMA. We adopt the gradient forwarding approach, where the sender simply broadcasts a packet and the receivers make the routing decision. Our contributions include the use of instantaneous signal-to-noise ratio (SNR) for the routing cost and the development of light-weight cost management based on flooding. They enable ORGMA to achieve high packet delivery ratio under dynamic MANET environments. Through NS-3 simulations, we evaluate ORGMA in comparison with other routing schemes, and the results show that ORGMA not only greatly outperforms the state-of-the-art routing schemes, but also achieves the performance close to an ideal routing scheme with global information.