Small-cell architecture is widely adopted by cellular network operators toincrease network capacity. By reducing the size of cells, operators can packmore (low-power) base stations in an area to better serve the growing demands,without causing extra interference. However, this approach suffers from lowspectrum temporal efficiency. When a cell becomes smaller and covers fewerusers, its total traffic fluctuates significantly due to insufficient trafficaggregation and exhibiting a large "peak-to-mean" ratio. As operatorscustomarily provision spectrum for peak traffic, large traffic temporalfluctuation inevitably leads to low spectrum temporal efficiency. In thispaper, we advocate device-to-device (D2D) load-balancing as a useful mechanismto address the fundamental drawback of small-cell architecture. The idea is toshift traffic from a congested cell to its adjacent under-utilized cells byleveraging inter-cell D2D communication, so that the traffic can be servedwithout using extra spectrum, effectively improving the spectrum temporalefficiency. We provide theoretical modeling and analysis to characterize thebenefit of D2D load balancing, in terms of total spectrum requirements of allindividual cells. We also derive the corresponding cost, in terms of incurredD2D traffic overhead. We carry out empirical evaluations based on real-world 4Gdata traces to gauge the benefit and cost of D2D load balancing under practicalsettings. The results show that D2D load balancing can reduce the spectrumrequirement by 25% as compared to the standard scenario without D2D loadbalancing, at the expense of negligible 0.7% D2D traffic overhead.
展开▼
