Routing in an ad hoc wireless network is a very important topic, especially considering the presence of malicious nodes. The authors propose a novel trust-based opportunistic routing protocol. A simulation is implemented and three metrics (RTOR, TORDP, and GEOTOR) are evaluated when considering next hop selection. The evaluation shows that all three proposed metrics performed better than the baseline for hop count, end-to-end delay, and packet delivery rate.

The paper is easy to read and the proposed protocol is simple. The three metrics are straightforward to understand. However, some parts of the paper are lacking in details. The attacker’s role is to act as a black hole and drop packets. This is too simplistic of an adversary model. A real attacker would try to collude--“bad mouth”--honest nodes to trick other nodes into giving them a low trust value, and change behavior so that their trust level does not fall too low. On a related note, the simulation performed is too simple. Varying the delivery probability is more realistic. In addition, a more detailed description of the watchdog mechanism is needed. The authors claim it is a “well-known approach” without giving any reference. There are also some grammatical mistakes throughout the paper.

Overall, the paper is easy to read and tackles an important topic, but lacks details on the trust-based protocol, realistic simulations, and attacker model.