17,647 research outputs found
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
Benchmarking Practical RRM Algorithms for D2D Communications in LTE Advanced
Device-to-device (D2D) communication integrated into cellular networks is a
means to take advantage of the proximity of devices and allow for reusing
cellular resources and thereby to increase the user bitrates and the system
capacity. However, when D2D (in the 3rd Generation Partnership Project also
called Long Term Evolution (LTE) Direct) communication in cellular spectrum is
supported, there is a need to revisit and modify the existing radio resource
management (RRM) and power control (PC) techniques to realize the potential of
the proximity and reuse gains and to limit the interference at the cellular
layer. In this paper, we examine the performance of the flexible LTE PC tool
box and benchmark it against a utility optimal iterative scheme. We find that
the open loop PC scheme of LTE performs well for cellular users both in terms
of the used transmit power levels and the achieved
signal-to-interference-and-noise-ratio (SINR) distribution. However, the
performance of the D2D users as well as the overall system throughput can be
boosted by the utility optimal scheme, because the utility maximizing scheme
takes better advantage of both the proximity and the reuse gains. Therefore, in
this paper we propose a hybrid PC scheme, in which cellular users employ the
open loop path compensation method of LTE, while D2D users use the utility
optimizing distributed PC scheme. In order to protect the cellular layer, the
hybrid scheme allows for limiting the interference caused by the D2D layer at
the cost of having a small impact on the performance of the D2D layer. To
ensure feasibility, we limit the number of iterations to a practically feasible
level. We make the point that the hybrid scheme is not only near optimal, but
it also allows for a distributed implementation for the D2D users, while
preserving the LTE PC scheme for the cellular users.Comment: 30 pages, submitted for review April-2013. See also: G. Fodor, M.
Johansson, D. P. Demia, B. Marco, and A. Abrardo, A joint power control and
resource allocation algorithm for D2D communications, KTH, Automatic Control,
Tech. Rep., 2012, qC 20120910,
http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10205
Average Rate of Downlink Heterogeneous Cellular Networks over Generalized Fading Channels - A Stochastic Geometry Approach
In this paper, we introduce an analytical framework to compute the average
rate of downlink heterogeneous cellular networks. The framework leverages
recent application of stochastic geometry to other-cell interference modeling
and analysis. The heterogeneous cellular network is modeled as the
superposition of many tiers of Base Stations (BSs) having different transmit
power, density, path-loss exponent, fading parameters and distribution, and
unequal biasing for flexible tier association. A long-term averaged maximum
biased-received-power tier association is considered. The positions of the BSs
in each tier are modeled as points of an independent Poisson Point Process
(PPP). Under these assumptions, we introduce a new analytical methodology to
evaluate the average rate, which avoids the computation of the Coverage
Probability (Pcov) and needs only the Moment Generating Function (MGF) of the
aggregate interference at the probe mobile terminal. The distinguishable
characteristic of our analytical methodology consists in providing a tractable
and numerically efficient framework that is applicable to general fading
distributions, including composite fading channels with small- and mid-scale
fluctuations. In addition, our method can efficiently handle correlated
Log-Normal shadowing with little increase of the computational complexity. The
proposed MGF-based approach needs the computation of either a single or a
two-fold numerical integral, thus reducing the complexity of Pcov-based
frameworks, which require, for general fading distributions, the computation of
a four-fold integral.Comment: Accepted for publication in IEEE Transactions on Communications, to
appea
On Modeling Coverage and Rate of Random Cellular Networks under Generic Channel Fading
In this paper we provide an analytic framework for computing the expected
downlink coverage probability, and the associated data rate of cellular
networks, where base stations are distributed in a random manner. The provided
expressions are in computable integral forms that accommodate generic channel
fading conditions. We develop these expressions by modelling the cellular
interference using stochastic geometry analysis, then we employ them for
comparing the coverage resulting from various channel fading conditions namely
Rayleigh and Rician fading, in addition to the fading-less channel.
Furthermore, we expand the work to accommodate the effects of random frequency
reuse on the cellular coverage and rate. Monte-Carlo simulations are conducted
to validate the theoretical analysis, where the results show a very close
match
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