Energy efficient network-flow-based algorithm for multiuser multicarrier systems

The resource allocation problem of minimising transmission power with per user rate constraint is studied for energy efficiency of multiuser multicarrier systems. The authors introduce an algorithm that deploys a flow-based decomposition strategy, called the network-flow-based algorithm (NFBA), to circumvent the NP-hard complexity of the resource allocation problem. The authors prove global optimality of the algorithm for the case of a flat-fading channel. For the general frequency selective channel, the flow size is adjusted adaptively to minimise the transmission power. Also, a compact integer programming formulation is developed to provide tight lower and upper bounds of the minimum power. Numerical results show that the authors´ proposed NFBA achieves near-optimal performance with polynomial complexity even for large-scale systems.