Performance Analysis and Simulation of a Freifunk Mesh Network in Paderborn using B.A.T.M.A.N Advanced

Free networks are established and maintained by more and more people on a voluntary basis to be independent from commercial providers. This also enables an uncensored communication and leads to a network owned by a community. Freifunk is such a project and it is based on wireless mesh networks. All participants provide an own wifi router (node) for transferring data between different devices. The routing protocol used in the Freifunk network of Paderborn is called Better Approach To Mobile Ad-hoc Networking advanced (B.A.T.M.A.N. IV or Batman-adv). It uses so called Originator Messages (OGM) to announce the existence of a node and to measure the quality of different links in the network. The Freifunk network in Paderborn consists of about 800 nodes that periodically broadcast OGMs. This leads to a substantial base load of ∼25 GByte per month and node. Instead of performing modifications in the real network, I create a simulation model of the current network structure and implement version IV of the B.A.T.M.A.N. routing protocol. The model is validated by using data from the real network. Based on this model I propose and evaluate five different opportunities to improve the base load without impairing other functionality of the network. The simulation results show that a combination of two improvements can lead to a reduction up to 90 %.