DHTs for Cluster-Based Ad-Hoc Networks Employing Multi-Hop Relaying

Distributed hash tables (DHTs) provide reliable distributed data management in a decentralized fashion that is well suited to self-organizing cluster-based ad-hoc networks. However, existing DHT approaches strive to optimize some combination of the total overlay message load, lookup delays, or load balance between the overlay nodes while ignoring the underlying physical characteristics of ad-hoc networks without infrastructure. In such networks, this inevitably leads to a high overhead in terms of the number of physical underlay transmissions. While location aware DHT approaches do reduce the number of underlay transmissions, they are not designed to exploit physical and link layer communication techniques such as cluster-based ad- hoc network structure or cooperative relaying. In this paper, we introduce novel location and resource aware DHT protocols that incorporate underlay cluster information into their proximity link selection. These and existing DHT protocols are evaluated in simulations that use realistic wireless transmission protocols and parameters along with mobile nodes with limited lifetimes. Comparisons of the number of required overlay and underlay hops as well as the amount of consumed power suggest a tradeoff between the underlay and overlay overhead in existing schemes, while the proposed novel protocols demonstrate both overlay and underlay benefits.