Fairness based dynamic channel assignment for in-building ultra dense networks

In ultra dense networks (UDNs), a large number of small-cell base stations (SBSs) are densely deployed in hotspots, e.g., office buildings, residential apartments, shopping malls, etc. Thus, SBSs have more serious interference between them in UDNs than they have in heterogeneous networks (HetNets) and it is a crucial issue to assign subchannels with consideration of the interference to satisfy the demands of small-cell user equipments (SUEs) for UDNs. In this paper, I propose a novel dynamic channel assignment (DCA) scheme named fairness based dynamic channel assignment (FDCA) to improve the system capacity of SUEs with guaranteeing the fairness for the downlink of in-building UDNs based on orthogonal frequency division multiple access-frequency division duplex. In the proposed FDCA scheme, a network controller unit first generates an interference matrix using channel state information from SUEs in UDNs and then it fairly assigns different numbers of subchannels to SUEs through their serving SBSs based on the interference matrix and optimal values of the signal to interference plus noise ratio threshold. Through simulation results, I show that the proposed FDCA scheme outperforms other DCA schemes using graph coloring algorithm in terms of the fairness with the reduced mean SUE capacity slightly. That is, the mean SUE capacity of the proposed FDCA scheme decreases 1 $$\sim $$ ∼ 5% than that of other schemes while the fairness index of it increases 16 $$\sim $$ ∼ 21% when the numbers of SBSs and SUEs are 25 and 100, respectively.