Kazuya Kumekawa

A MANET protocol considering link stability and bandwidth efficiency

A mobile ad hoc network (MANET) is an autonomous collection of mobile nodes that communicate over relatively bandwidth constrained wireless links. Frequent link changes and limited bandwidth make communication in MANET particularly challenging. Based on AODV, we propose a MANET routing protocol considering link stability and bandwidth efficiency. The protocol uses distributed Q-Learning to infer network status information and takes in to consideration link stability and bandwidth efficiency while selecting a route. The protocol can efficiently handle network mobility by a way of preemptively switching to a better route before current route fails. We study the performance of this protocol through simulation and demonstrate its significant improvement compared to AODV.

A hierarchical group key management scheme for secure multicast increasing efficiency of key distribution in leave operation

This paper proposes an efficient protocol and associate algorithm for group key management in secure multicast. This protocol is based on a hierarchy approach in which the group is logically divided into subgroups. The group key is organized using member secrets assigned to each member and server secrets assigned to each subgroup, and the inverse value of the member secrets are also used to manage the group key when a member leaves. In this case, each member in a single subgroup needs to store the inverse values of the other members in that subgroup with the exception of its own. When a member joins the group, after updating the previous group key in the server, the new key is sent to all existing group members, and the inverse value of the new member is sent to subgroup members (where there is a join), by exploiting IP multicast. Most importantly, the server just sends the inverse value of the leaving member to the subgroups when a member leaves. Then, the group key is updated by each remaining member in the subgroups by using that inverse value. Consequently, the benefits are two-fold. First, only one key needs to be generated by the server at each event. Second, not only the computational overhead is reduced but also new key information can be multicast to all members simultaneously. This paper describes the details of our novel protocol and the related algorithm.

A dynamic route change mechanism for mobile ad hoc networks

A mobile ad hoc network (MANET) is a self-configuring network of mobile devices connected by wireless links. Frequent topology changes and limited bandwidth make communication in MANETs particularly challenging. We present a MANET routing protocol that can efficiently handle network mobility by a way of preemptively switching to a better route before the current route fails. The protocol uses a distributed Q-learning algorithm to infer network status information and takes in to consideration link stability and bandwidth efficiency while selecting a route. We study the performance of this protocol through simulation and demonstrate its advantages over existing protocols.