Framework for utility driven congestion control in delay tolerant opportunistic networks

Detecting and dealing with congestion in delay tolerant opportunistic networks is an important and challenging problem. In this paper we describe CAFREP, a unified congestion control framework for routing in such networks that adapts both data sending rates and data forwarding policies through a novel reactive fully distributed approach. CAFREP enables congestion control by detecting and reacting to congested nodes and congested parts of the network by using implicit hybrid contact and resources congestion heuristic. CAFREP exploits localized relative utility based approach to offload the traffic from more to less congested parts of the network, and replicate at adaptively lower rate in parts of the network with higher congestion. We extensively evaluate CAFREP against a number of state of the art adaptive and non-adaptive DTN routing protocols across a number of different metrics over three real trace driven experiments with different mobility and connectivity patterns such as Infocom 2006, Rollernet and Dieselnet CRAWDAD data sets. We show that CAFREP performs well in three different connectivity datasets and continuously outperforms four other protocols in terms of maintaining higher node availability and success ratio while keeping lower delays, lower packet loss rates and lower number of forwarded packets for increasing congestion levels.