On the inadequacy of MANET routing to efficiently use the wireless capacity

Wireless bandwidth is a limited and scarce shared resource in MANETs. A number of experimental and analytical studies have shown that the multi-hop nature results in nodes experience low bandwidth. Compounding this problem further are the routing protocols themselves: as they typically minimize either hop count or number of packet retransmissions, they favor routes in the centre of a MANET. This results in a reduction of spatial reuse, inefficiently using the scarce wireless bandwidth. In our work, we are interested in the "end-to-end capacity" of the network, which we define to be the sum of the throughputs for each flow. This represents the service a network provides to its users. In this paper, we determine the maximal MANET capacity through linear programming and evaluate the performance of AODV and DSR with respect to this maximum value. The result shows that these typical MANET routing protocols do not utilize the network resources efficiently, achieving less than 17% of that capacity even in the best possible case. New routing protocols are therefore required to make more efficient use of this limited resource.