1,779 research outputs found
Analysis of Multi-Cell Downlink Cooperation with a Constrained Spatial Model
Multi-cell cooperation (MCC) mitigates intercell interference and improves
throughput at the cell edge. This paper considers a cooperative downlink,
whereby cell-edge mobiles are served by multiple cooperative base stations. The
cooperating base stations transmit identical signals over paths with
non-identical path losses, and the receiving mobile performs diversity
combining. The analysis in this paper is driven by a new expression for the
conditional outage probability when signals arriving over different paths are
combined in the presence of noise and interference, where the conditioning is
with respect to the network topology and shadowing. The channel model accounts
for path loss, shadowing, and Nakagami fading, and the Nakagami fading
parameters do not need to be identical for all paths. To study performance over
a wide class of network topologies, a random spatial model is adopted, and
performance is found by statistically characterizing the rates provided on the
downlinks. To model realistic networks, the model requires a minimum separation
among base stations. Having adopted a realistic model and an accurate analysis,
the paper proceeds to determine performance under several resource-allocation
policies and provides insight regarding how the cell edge should be defined.Comment: 6 pages, 3 figures, IEEE Global Telecommun. Conf. (GLOBECOM), 2013,
to appear. arXiv admin note: text overlap with arXiv:1210.366
Opportunistic Third-Party Backhaul for Cellular Wireless Networks
With high capacity air interfaces and large numbers of small cells, backhaul
-- the wired connectivity to base stations -- is increasingly becoming the cost
driver in cellular wireless networks. One reason for the high cost of backhaul
is that capacity is often purchased on leased lines with guaranteed rates
provisioned to peak loads. In this paper, we present an alternate
\emph{opportunistic backhaul} model where third parties provide base stations
and backhaul connections and lease out excess capacity in their networks to the
cellular provider when available, presumably at significantly lower costs than
guaranteed connections. We describe a scalable architecture for such
deployments using open access femtocells, which are small plug-and-play base
stations that operate in the carrier's spectrum but can connect directly into
the third party provider's wired network. Within the proposed architecture, we
present a general user association optimization algorithm that enables the
cellular provider to dynamically determine which mobiles should be assigned to
the third-party femtocells based on the traffic demands, interference and
channel conditions and third-party access pricing. Although the optimization is
non-convex, the algorithm uses a computationally efficient method for finding
approximate solutions via dual decomposition. Simulations of the deployment
model based on actual base station locations are presented that show that large
capacity gains are achievable if adoption of third-party, open access
femtocells can reach even a small fraction of the current market penetration of
WiFi access points.Comment: 9 pages, 6 figure
Performance Analysis of Fifth-Generation Cellular Uplink
Fifth-generation cellular networks are expected to exhibit at least three
primary physical-layer differences relative to fourth-generation ones:
millimeter-wave propagation, antenna-array directionality, and densification of
base stations. In this paper, the effects of these differences on the
performance of single-carrier frequency-domain multiple-access uplink systems
with frequency hopping are assessed. A new analysis, which is much more
detailed than any other in the existing literature and accommodates actual
base-station topologies, captures the primary features of uplink
communications. Distance-dependent power-law, shadowing, and fading models
based on millimeter-wave measurements are introduced. The beneficial effects of
base-station densification, highly directional sectorization, and frequency
hopping are illustrated.Comment: 6 pages, 5 figures, IEEE Military Commun. Conf. (MILCOM), 201
Coverage and Economy of Cellular Networks with Many Base Stations
The performance of a cellular network can be significantly improved by
employing many base stations (BSs), which shortens transmission distances.
However, there exist no known results on quantifying the performance gains from
deploying many BSs. To address this issue, we adopt a stochastic-geometry model
of the downlink cellular network and analyze the mobile outage probability.
Specifically, given Poisson distributed BSs, the outage probability is shown to
diminish inversely with the increasing ratio between the BS and mobile
densities. Furthermore, we analyze the optimal tradeoff between the performance
gain from increasing the BS density and the resultant network cost accounting
for energy consumption, BS hardware and backhaul cables. The optimal BS density
is proved to be proportional to the square root of the mobile density and the
inverse of the square root of the cost factors considered.Comment: 3 pages, 3 figures, to appear in IEEE Communications Letter
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