Analysis of Buffer Management Policies for Opportunistic Networks

Opportunistic Networks are a subclass of delay tolerant networks, which aims at wireless data delivery in severely partitioned networks. Messages are routed on a best effort basis. If nodes cannot forward messages due to missing connectivity, the messages are buffered according to a queue policy, and scheduled for transmission once there is a connection again. In case of congestion, nodes drop messages based on a drop policy. The scheduling and the drop policy form together the buffer management policy, which has an impact on routing performance. Although a multitude of different policies exist, there has not yet been a comprehensive study regarding routing performance, which compares all possible policies against each other. In this paper, we conduct this comprehensive study and investigate the impact of the various parameters a message has, namely the arrival time, replication count, number of relayed nodes, time to live and message size, on the performance of the routing in an opportunistic network. In specific, this paper analyzes epidemic routing with 121 different policies and compares them in terms of delivery ratio, overhead and latency in three use cases. Evaluation shows the strengths and weaknesses of the various buffer management policies and highlights, that there is not one policy that is always to recommend. This study will help to create dynamic buffer management policies, which adapt to the given network characteristics and select suitable parameters to prioritize.