Quality of service in delay tolerant networks: A survey

Delay tolerant networks (DTNs) are characterized by the absence of the end-to-end path due to intermittent connectivity among the nodes. Such networks are potentially applicable in the challenging scenarios, e.g. interplanetary communication, post-disaster environment, where traditional communication infrastructure is partially or fully absent. Each application requires some quality of service (QoS) guarantees for the traffic flow. QoS support cannot be provided to a network without QoS provisioning. However, QoS provisioning in a DTN is more difficult task than traditional networks, because of its inherent characteristics. There exist various issues which affect QoS in DTNs. In this paper, we explore the issues that influence QoS in DTNs. Subsequently, we analyze the effects of the issues on the QoS in terms of delivery ratio, packet drop etc. We also review various QoS management solutions in DTNs. The schemes on the QoS issues are classified based on their underlying approaches and key features. The paper is concluded with a brief discussion on some of the open research issues regarding QoS in DTNs.