Will the area spectral efficiency monotonically grow as small cells go dense?

© 2015 IEEE. In this paper, we introduce a sophisticated path loss model into the stochastic geometry analysis incorporating both line-of-sight (LoS) and non- line-of-sight (NLoS) transmissions to study their performance impact in small cell networks (SCNs). Analytical results are obtained on the coverage probability and the area spectral efficiency (ASE) assuming both a general path loss model and a special case of path loss model recommended by the 3rd Generation Partnership Project (3GPP) standards. The performance impact of LoS and NLoS transmissions in SCNs in terms of the coverage probability and the ASE is shown to be significant both quantitatively and qualitatively, compared with previous work that does not differentiate LoS and NLoS transmissions. From the investigated set of parameters, our analysis demonstrates that when the density of small cells is larger than a threshold, the network coverage probability will decrease as small cells become denser, which in turn makes the ASE suffer from a slow growth or even a notable decrease. For practical regime of small cell density, the performance results derived from our analysis are distinctively different from previous results, and shed new insights on the design and deployment of future dense/ultra-dense SCNs. It is of significant interest to further study the generality of our conclusion in other network models and with other parameter sets

Uplink performance analysis of dense cellular networks with LoS and NLoS transmissions

© 2016 IEEE. In this paper, we analyse the coverage probability and the area spectral efficiency (ASE) in the uplink (UL) of dense small cell networks (SCNs) considering a piecewise linear path loss model incorporating both line-of-sight (LoS) and non-line-of-sight (NLoS) transmissions. The performance impact of LoS and NLoS transmissions in the ASE of the UL of dense SCNs is shown to be significant, both quantitatively and qualitatively, compared with previous works that do not differentiate LoS and NLoS transmissions. In particular, previous works predicted that a larger UL power compensation factor would always result in a better ASE in the practical range of user equipment (UE) density, i.e., 100 ∼ 103 UEs/km2. However, our results show that a smaller UL power compensation factor can greatly boost the ASE in the UL of dense SCNs, i.e., 102∼103 UEs/km2, while a larger UL power compensation factor is more suitable for sparse SCNs, i.e., 100∼102 UEs/km2

Coverage and Rate Analysis for Unmanned Aerial Vehicle Base Stations with LoS/NLoS Propagation

The use of unmanned aerial vehicle base stations (UAV-BSs) as airborne base stations has recently gained great attention. In this paper, we model a network of UAV-BSs as a Poisson point process (PPP) operating at a certain altitude above the ground users. We adopt an air-to-ground (A2G) channel model that incorporates line-of-sight (LoS) and non-line-of-sight (NLoS) propagation. Thus, UAV-BSs can be decomposed into two independent inhomogeneous PPPs. Under the assumption that NLoS and LoS channels experience Rayleigh and Nakagami-m fading, respectively, we derive approximations for the coverage probability and average achievable rate, and show that these approximations match the simulations with negligible errors. Numerical simulations have shown that the coverage probability and average achievable rate decrease as the height of the UAV-BSs increases