MODSPIRITE: A Credit Based Solution to Enforce Node Cooperation in an Ad-hoc Network

In an Ad-hoc network, node cooperation is an important factor for successful data transmission among nodes. Most of the routing protocols are based on the assumption that the intermediate node cooperates during data transmission from source node to destination. However, because mobile nodes are constrained by limited energy, bandwidth and computational resources, a node sometimes behaves as selfish to conserve its resources like energy, bandwidth etc. These selfish nodes are unwilling to forward others’ packets. This paper gives a review of existing reputation based and credit based systems and proposes a credit based solution called MODSPIRIT which is a modification of SPIRITE system. MODSPIRITE system detects selfish node using neighbor monitoring mechanism and enforce cooperation among non cooperative node by providing incentives to intermediate nodes. One of the limitations of SPIRITE system is that sender loses too much credit to forward its data to the destination and for future sender have very less or no credit to forward its data. As compared to SPIRITE, MODSPIRITE reduces overhead of sender for upto 25%. It also punishes noncooperative nodes so that non cooperative node get discourage.