14,677 research outputs found
Asymptotic Behavior of Ultra-Dense Cellular Networks and Its Economic Impact
This paper investigates the relationship between base station (BS) density
and average spectral efficiency (SE) in the downlink of a cellular network.
This relationship has been well known for sparse deployment, i.e. when the
number of BSs is small compared to the number of users. In this case the SE is
independent of BS density. As BS density grows, on the other hand, it has
previously been shown that increasing the BS density increases the SE, but no
tractable form for the SE-BS density relationship has yet been derived. In this
paper we derive such a closed-form result that reveals the SE is asymptotically
a logarithmic function of BS density as the density grows. Further, we study
the impact of this result on the network operator's profit when user demand
varies, and derive the profit maximizing BS density and the optimal amount of
spectrum to be utilized in closed forms. In addition, we provide deployment
planning guidelines that will aid the operator in his decision if he should
invest in densifying his network or in acquiring more spectrum.Comment: This paper will appear in Proc. IEEE Global Commun. Conf. (GLOBECOM)
201
Optimal Non-uniform Deployments in Ultra-Dense Finite-Area Cellular Networks
Network densification and heterogenisation through the deployment of small
cellular access points (picocells and femtocells) are seen as key mechanisms in
handling the exponential increase in cellular data traffic. Modelling such
networks by leveraging tools from Stochastic Geometry has proven particularly
useful in understanding the fundamental limits imposed on network coverage and
capacity by co-channel interference. Most of these works however assume
infinite sized and uniformly distributed networks on the Euclidean plane. In
contrast, we study finite sized non-uniformly distributed networks, and find
the optimal non-uniform distribution of access points which maximises network
coverage for a given non-uniform distribution of mobile users, and vice versa.Comment: 4 Pages, 6 Figures, Letter for IEEE Wireless Communication
Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks
Soaring capacity and coverage demands dictate that future cellular networks
need to soon migrate towards ultra-dense networks. However, network
densification comes with a host of challenges that include compromised energy
efficiency, complex interference management, cumbersome mobility management,
burdensome signaling overheads and higher backhaul costs. Interestingly, most
of the problems, that beleaguer network densification, stem from legacy
networks' one common feature i.e., tight coupling between the control and data
planes regardless of their degree of heterogeneity and cell density.
Consequently, in wake of 5G, control and data planes separation architecture
(SARC) has recently been conceived as a promising paradigm that has potential
to address most of aforementioned challenges. In this article, we review
various proposals that have been presented in literature so far to enable SARC.
More specifically, we analyze how and to what degree various SARC proposals
address the four main challenges in network densification namely: energy
efficiency, system level capacity maximization, interference management and
mobility management. We then focus on two salient features of future cellular
networks that have not yet been adapted in legacy networks at wide scale and
thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and
device-to-device (D2D) communications. After providing necessary background on
CoMP and D2D, we analyze how SARC can particularly act as a major enabler for
CoMP and D2D in context of 5G. This article thus serves as both a tutorial as
well as an up to date survey on SARC, CoMP and D2D. Most importantly, the
article provides an extensive outlook of challenges and opportunities that lie
at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201
Ultra-Dense Networks: Is There a Limit to Spatial Spectrum Reuse?
The aggressive spatial spectrum reuse (SSR) by network densification using
smaller cells has successfully driven the wireless communication industry
onward in the past decades. In our future journey toward ultra-dense networks
(UDNs), a fundamental question needs to be answered. Is there a limit to SSR?
In other words, when we deploy thousands or millions of small cell base
stations (BSs) per square kilometer, is activating all BSs on the same
time/frequency resource the best strategy? In this paper, we present
theoretical analyses to answer such question. In particular, we find that both
the signal and interference powers become bounded in practical UDNs with a
non-zero BS-to-UE antenna height difference and a finite UE density, which
leads to a constant capacity scaling law. As a result, there exists an optimal
SSR density that can maximize the network capacity. Hence, the limit to SSR
should be considered in the operation of future UDNs.Comment: conference submission in Oct. 201
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