Fair and optimal mobile assisted offloading

We study an offloading mechanism for cellular networks in which mobiles with good cellular links can act as hotspots and can assist other mobiles. We study throughput optimal offloading and also a fair offloading strategy which we call proportional increment offloading. We show that the former problem can be reduced to a capacitated facility location problem (CFLP) whereas the latter can be solved by solving a sequence of CFLPs. We propose a belief propagation based algorithm to solve CFLP, a well known NP complete problem. We primarily consider point coordination function (PCF) based WiFi access for offloading but also discuss distributed coordination function (DCF) based access and related issues. Further, we argue that all the mobiles benefit through participating in offloading. We perform extensive simulation to evaluate the performance of the proposed algorithms and effectiveness of mobile assisted offloading.