Cross-Layer Offloading in Fog-RANs Using Device Cooperation and Network Coding
Kameliya Kaneva, Neda Aboutorab, Sameh Sorour, Mark C. Reed · 2018
This paper studies the Fog Radio Access Networks (F-RANs) where smart user devices, called F-UEs, can communicate and cooperate with each other in order to reduce the load on the central baseband processing unit (BBU) and consequently, increase the capacity of the system. Here, we propose a cross-layer approach to offload the BBU taking into account each F-UE's download rates which represent the actual physical conditions of its channel. The algorithm's second priority is also to reduce the transmission times between the F-UEs. The BBU and F-UE devices in our system utilize network coding (NC) so that they can target more receivers with one coded transmission and thus, communicate more efficiently. Initially, we formulate the problem of cross-layer BBU offloading as an optimization problem, model it onto an NC conflict graph, and prove its NP-hardness. Then, a heuristic algorithm is proposed to efficiently schedule the coded transmissions between all devices in the network so that the BBU transmits in minimum time. Simulation results show that our proposed algorithm achieves not only better physical offloading of the BBU compared to the upper-layer (i.e., non cross-layer) scheme but also reduces the energy consumption of the F-UEs.