Clustering Schemes for D2D Communications under Partial/No Network Coverage

Device-to-device (D2D) communications as an underlay to cellular networks can not only increase the system capacity and energy efficiency, but it can also enable national security and public safety (NSPS) services. A key requirement is to provide access to cellular services when the network is available and maintain local communication in the (partial) absence of the infrastructure. In this paper we propose and compare clustering schemes that are applicable for integrating D2D communications into cellular networks such that communication services can be maintained when the cellular infrastructure becomes partially dysfunctional. Our results show that there is a trade-off between coverage, energy efficiency and cluster formation delay and this trade-off can be handled by our proposed threshold-based clustering scheme.