The role and scope of a service discovery protocol (SDP) in a wireless ad-hoc network differs from that in wire-line

In this paper we address the problem of service directory placement in wireless ad-hoc networks. In particular, we introduce the Service Directory Placement Protocol, or SDPP, which enables directory-based service discovery in wireless adhoc networks. In our approach, the service directory is moved from one host to another in response to the dynamics of a service discovery overlay system and the network topology, as opposed to having a service directory confined to a single host. The objective is to incur in less bandwidth overhead by conveniently placing the directory in a network neighbourhood wherein a significant amount of service discovery queries are likely to be generated at that point in time. To accomplish this objective, we formulate the directory placement problem as a Semi-Markov Decision Process. The challenge here is to find an efficient policy for directory placement by means of the Reinforcement Learning technique within the context of a low-mobility wireless ad-hoc network. Performance measurements depicting the degree of effectiveness introduced by our approach, as well as its limitations are presented as part of an ongoing investigation.