Performance Impact of Idle Mode Capability on Dense Small Cell Networks with LoS and NLoS Transmissions
In dense small cell networks (SCNs), a large number of base stations (BSs) can be put to idle modes without signal transmission, if there is no active user equipment (UE) within their coverage areas. Setting those BSs to idle modes can mitigate unnecessary inter-cell interference and reduce energy consumption. Such idle mode feature at BSs is referred to as the idle mode capability (IMC). In this paper, we study the performance impact of the BS IMC on dense SCNs. Different from existing work, we consider a sophisticated and more realistic path loss model incorporating both line-of-sight (LoS) and non-line-of-sight (NLoS) transmissions. Analytical results are obtained for the coverage probability, the area spectral efficiency and the energy efficiency performance for SCNs with the BS IMC. An upper bound, a lower bound and an approximate expression of the density of the non-idle BSs are also derived. The performance impact of the IMC on network densification is shown to be significant. As the BS density surpasses the UE density, thus creating a surplus of BSs, the coverage probability will continuously increase toward one, which addresses the critical issue of coverage probability decrease caused by the LoS/NLoS transmissions.