14,842 research outputs found
The Impact of Antenna Height Difference on the Performance of Downlink Cellular Networks
Capable of significantly reducing cell size and enhancing spatial reuse,
network densification is shown to be one of the most dominant approaches to
expand network capacity. Due to the scarcity of available spectrum resources,
nevertheless, the over-deployment of network infrastructures, e.g., cellular
base stations (BSs), would strengthen the inter-cell interference as well, thus
in turn deteriorating the system performance. On this account, we investigate
the performance of downlink cellular networks in terms of user coverage
probability (CP) and network spatial throughput (ST), aiming to shed light on
the limitation of network densification. Notably, it is shown that both CP and
ST would be degraded and even diminish to be zero when BS density is
sufficiently large, provided that practical antenna height difference (AHD)
between BSs and users is involved to characterize pathloss. Moreover, the
results also reveal that the increase of network ST is at the expense of the
degradation of CP. Therefore, to balance the tradeoff between user and network
performance, we further study the critical density, under which ST could be
maximized under the CP constraint. Through a special case study, it follows
that the critical density is inversely proportional to the square of AHD. The
results in this work could provide helpful guideline towards the application of
network densification in the next-generation wireless networks.Comment: conference submission - Mar. 201
Spatial Coordination Strategies in Future Ultra-Dense Wireless Networks
Ultra network densification is considered a major trend in the evolution of
cellular networks, due to its ability to bring the network closer to the user
side and reuse resources to the maximum extent. In this paper we explore
spatial resources coordination as a key empowering technology for next
generation (5G) ultra-dense networks. We propose an optimization framework for
flexibly associating system users with a densely deployed network of access
nodes, opting for the exploitation of densification and the control of overhead
signaling. Combined with spatial precoding processing strategies, we design
network resources management strategies reflecting various features, namely
local vs global channel state information knowledge exploitation, centralized
vs distributed implementation, and non-cooperative vs joint multi-node data
processing. We apply these strategies to future UDN setups, and explore the
impact of critical network parameters, that is, the densification levels of
users and access nodes as well as the power budget constraints, to users
performance. We demonstrate that spatial resources coordination is a key factor
for capitalizing on the gains of ultra dense network deployments.Comment: An extended version of a paper submitted to ISWCS'14, Special Session
on Empowering Technologies of 5G Wireless Communication
Technical Rate of Substitution of Spectrum in Future Mobile Broadband Provisioning
Dense deployment of base stations (BSs) and multi-antenna techniques are
considered key enablers for future mobile networks. Meanwhile, spectrum sharing
techniques and utilization of higher frequency bands make more bandwidth
available. An important question for future system design is which element is
more effective than others. In this paper, we introduce the concept of
technical rate of substitution (TRS) from microeconomics and study the TRS of
spectrum in terms of BS density and antenna number per BS. Numerical results
show that TRS becomes higher with increasing user data rate requirement,
suggesting that spectrum is the most effective means of provisioning extremely
fast mobile broadband.Comment: 5 pages, 5 figures, conferenc
Study on Scheduling Techniques for Ultra Dense Small Cell Networks
The most promising approach to enhance network capacity for the next
generation of wireless cellular networks (5G) is densification, which benefits
from the extensive spatial reuse of the spectrum and the reduced distance
between transmitters and receivers. In this paper, we examine the performance
of different schedulers in ultra dense small cell deployments. Due to the
stronger line of sight (LOS) at low inter-site distances (ISDs), we discuss
that the Rician fading channel model is more suitable to study network
performance than the Rayleigh one, and model the Rician K factor as a function
of distance between the user equipment (UE) and its serving base station (BS).
We also construct a cross-correlation shadowing model that takes into account
the ISD, and finally investigate potential multi-user diversity gains in ultra
dense small cell deployments by comparing the performances of proportional fair
(PF) and round robin (RR) schedulers. Our study shows that as network becomes
denser, the LOS component starts to dominate the path loss model which
significantly increases the interference. Simulation results also show that
multi-user diversity is considerably reduced at low ISDs, and thus the PF
scheduling gain over the RR one is small, around 10% in terms of cell
throughput. As a result, the RR scheduling may be preferred for dense small
cell deployments due to its simplicity. Despite both the interference
aggravation as well as the multi-user diversity loss, network densification is
still worth it from a capacity view point.Comment: 6 pages, 7 figures, Accepted to IEEE VTC-Fall 2015 Bosto
- …