6,546 research outputs found
Downlink Performance Analysis for a Generalized Shotgun Cellular System
In this paper, we analyze the signal-to-interference-plus-noise ratio (SINR)
performance at a mobile station (MS) in a random cellular network. The cellular
network is formed by base-stations (BSs) placed in a one, two or three
dimensional space according to a possibly non-homogeneous Poisson point
process, which is a generalization of the so-called shotgun cellular system. We
develop a sequence of equivalence relations for the SCSs and use them to derive
semi-analytical expressions for the coverage probability at the MS when the
transmissions from each BS may be affected by random fading with arbitrary
distributions as well as attenuation following arbitrary path-loss models. For
homogeneous Poisson point processes in the interference-limited case with
power-law path-loss model, we show that the SINR distribution is the same for
all fading distributions and is not a function of the base station density. In
addition, the influence of random transmission powers, power control, multiple
channel reuse groups on the downlink performance are also discussed. The
techniques developed for the analysis of SINR have applications beyond cellular
networks and can be used in similar studies for cognitive radio networks,
femtocell networks and other heterogeneous and multi-tier networks.Comment: 30 pages, 8 figures, re-submitted to Transactions on Communications
on Sep-12 2012, initial submission to Transactions on Communications on
26-Apr 201
Modeling and Analysis of Cellular Networks using Stochastic Geometry: A Tutorial
This paper presents a tutorial on stochastic geometry (SG) based analysis for
cellular networks. This tutorial is distinguished by its depth with respect to
wireless communication details and its focus on cellular networks. The paper
starts by modeling and analyzing the baseband interference in a basic cellular
network model. Then, it characterizes signal-to-interference-plus-noise-ratio
(SINR) and its related performance metrics. In particular, a unified approach
to conduct error probability, outage probability, and rate analysis is
presented. Although the main focus of the paper is on cellular networks, the
presented unified approach applies for other types of wireless networks that
impose interference protection around receivers. The paper then extends the
baseline unified approach to capture cellular network characteristics (e.g.,
frequency reuse, multiple antenna, power control, etc.). It also presents
numerical examples associated with demonstrations and discussions. Finally, we
point out future research directions.Comment: Submitted to IEEE Communications Surveys and Tutorial
A Survey on 5G: The Next Generation of Mobile Communication
The rapidly increasing number of mobile devices, voluminous data, and higher
data rate are pushing to rethink the current generation of the cellular mobile
communication. The next or fifth generation (5G) cellular networks are expected
to meet high-end requirements. The 5G networks are broadly characterized by
three unique features: ubiquitous connectivity, extremely low latency, and very
high-speed data transfer. The 5G networks would provide novel architectures and
technologies beyond state-of-the-art architectures and technologies. In this
paper, our intent is to find an answer to the question: "what will be done by
5G and how?" We investigate and discuss serious limitations of the fourth
generation (4G) cellular networks and corresponding new features of 5G
networks. We identify challenges in 5G networks, new technologies for 5G
networks, and present a comparative study of the proposed architectures that
can be categorized on the basis of energy-efficiency, network hierarchy, and
network types. Interestingly, the implementation issues, e.g., interference,
QoS, handoff, security-privacy, channel access, and load balancing, hugely
effect the realization of 5G networks. Furthermore, our illustrations highlight
the feasibility of these models through an evaluation of existing
real-experiments and testbeds.Comment: Accepted in Elsevier Physical Communication, 24 pages, 5 figures, 2
table
D2D Enhanced Heterogeneous Cellular Networks with Dynamic TDD
Over the last decade, the growing amount of UL and DL mobile data traffic has
been characterized by substantial asymmetry and time variations. Dynamic
time-division duplex (TDD) has the capability to accommodate to the traffic
asymmetry by adapting the UL/DL configuration to the current traffic demands.
In this work, we study a two-tier heterogeneous cellular network (HCN) where
the macro tier and small cell tier operate according to a dynamic TDD scheme on
orthogonal frequency bands. To offload the network infrastructure, mobile users
in proximity can engage in D2D communications, whose activity is determined by
a carrier sensing multiple access (CSMA) scheme to protect the ongoing
infrastructure-based and D2D transmissions. We present an analytical framework
to evaluate the network performance in terms of load-aware coverage probability
and network throughput. The proposed framework allows to quantify the effect on
the coverage probability of the most important TDD system parameters, such as
the UL/DL configuration, the base station density, and the bias factor. In
addition, we evaluate how the bandwidth partition and the D2D network access
scheme affect the total network throughput. Through the study of the tradeoff
between coverage probability and D2D user activity, we provide guidelines for
the optimal design of D2D network access.Comment: 15 pages; 9 figures; submitted to IEEE Transactions on Wireless
Communication
Small Cell Offloading Through Cooperative Communication in Software-Defined Heterogeneous Networks
To meet the ever-growing demand for a higher communicating rate and better
communication quality, more and more small cells are overlaid under the macro
base station (MBS) tier, thus forming the heterogeneous networks. Small cells
can ease the load pressure of MBS but lack of the guarantee of performance. On
the other hand, cooperation draws more and more attention because of the great
potential of small cell densification. Some technologies matured in wired
network can also be applied to cellular networks, such as Software-defined
networking (SDN). SDN helps simplify the structure of multi-tier networks. And
it's more reasonable for the SDN controller to implement cell coordination. In
this paper, we propose a method to offload users from MBSs through small cell
cooperation in heterogeneous networks. Association probability is the main
indicator of offloading. By using the tools from stochastic geometry, we then
obtain the coverage probabilities when users are associated with different
types of base stations (BSs). All the cell association and cooperation are
conducted by the SDN controller. Then on this basis, we compare the overall
coverage probabilities, achievable rate and energy efficiency with and without
cooperation. Numerical results show that small cell cooperation can offload
more users from MBS tier. It can also increase the system's coverage
performance. As small cells become denser, cooperation can bring more gains to
the energy efficiency of the network.Comment: 12 pages, 7 figure
Spatial modeling and analysis of cellular networks using the Ginibre point process: A tutorial
Spatial stochastic models have been much used for performance analysis of
wireless communication networks. This is due to the fact that the performance
of wireless networks depends on the spatial configuration of wireless nodes and
the irregularity of node locations in a real wireless network can be captured
by a spatial point process. Most works on such spatial stochastic models of
wireless networks have adopted homogeneous Poisson point processes as the
models of wireless node locations. While this adoption makes the models
analytically tractable, it assumes that the wireless nodes are located
independently of each other and their spatial correlation is ignored. Recently,
the authors have proposed to adopt the Ginibre point process---one of the
determinantal point processes---as the deployment models of base stations (BSs)
in cellular networks. The determinantal point processes constitute a class of
repulsive point processes and have been attracting attention due to their
mathematically interesting properties and efficient simulation methods. In this
tutorial, we provide a brief guide to the Ginibre point process and its
variant, -Ginibre point process, as the models of BS deployments in
cellular networks and show some existing results on the performance analysis of
cellular network models with -Ginibre deployed BSs. The authors hope
the readers to use such point processes as a tool for analyzing various
problems arising in future cellular networks.Comment: IEICE Transactions on Communication
Effective Capacity in Wireless Networks: A Comprehensive Survey
Low latency applications, such as multimedia communications, autonomous
vehicles, and Tactile Internet are the emerging applications for
next-generation wireless networks, such as 5th generation (5G) mobile networks.
Existing physical-layer channel models, however, do not explicitly consider
quality-of-service (QoS) aware related parameters under specific delay
constraints. To investigate the performance of low-latency applications in
future networks, a new mathematical framework is needed. Effective capacity
(EC), which is a link-layer channel model with QoS-awareness, can be used to
investigate the performance of wireless networks under certain statistical
delay constraints. In this paper, we provide a comprehensive survey on existing
works, that use the EC model in various wireless networks. We summarize the
work related to EC for different networks such as cognitive radio networks
(CRNs), cellular networks, relay networks, adhoc networks, and mesh networks.
We explore five case studies encompassing EC operation with different design
and architectural requirements. We survey various delay-sensitive applications
such as voice and video with their EC analysis under certain delay constraints.
We finally present the future research directions with open issues covering EC
maximization
Offloading of Users in NOMA-HetNet Using Repulsive Point Process
Ever increasing number of cellular users and their high data requirements,
necessitates need for improvement in the present heterogeneous cellular
networks (HetNet). Carrier sensing prevents base stations within a certain
range of the transmitter from transmitting and hence aids in reducing the
interference. Non-orthogonal multiple access (NOMA) has proven its superiority
for the 5th generation (5G) networks. This work proposes a mathematical model
for an improved HetNet with macro base station (MBS) and femto base station
(FBS) tier. The FBS tier is equipped to support NOMA and carrier sensing for
its transmissions. Offloading is performed for load balancing in HetNet where
the macro users (MU) from congested MBS tier are offloaded to the FBS tier. The
FBS tier pairs the offloaded MU (OMU) with an appropriate pairing user (PU) to
perform NOMA. The performance of the OMU is studied under different channel
conditions with respect to the available PU at the FBS and some useful
observations are drawn. A decrease in outage probability by for cell
center user (CCU) and for cell edge user (CEU) is observed for low
density FBS. The outage probability decreases by , for both the CCU
and CEU, for high density FBS using the proposed carrier sensing in NOMA. The
results are validated using simulations
Hybrid Full-/Half-Duplex System Analysis in Heterogeneous Wireless Networks
Full-duplex (FD) radio has been introduced for bidirectional communications
on the same temporal and spectral resources so as to maximize spectral
efficiency. In this paper, motivated by the recent advances in FD radios, we
provide a foundation for hybrid-duplex heterogeneous networks (HDHNs), composed
of multi-tier networks with a mixture of access points (APs), operating either
in bidirectional FD mode or downlink half-duplex (HD) mode. Specifically, we
characterize the net- work interference from FD-mode cells, and derive the HDHN
throughput by accounting for AP spatial density, self-interference cancellation
(IC) capability, and transmission power of APs and users. By quantifying the
HDHN throughput, we present the effect of network parameters and the self-IC
capability on the HDHN throughput, and show the superiority of FD mode for
larger AP densities (i.e., larger network interference and shorter
communication distance) or higher self-IC capability. Furthermore, our results
show operating all APs in FD or HD achieves higher throughput compared to the
mixture of two mode APs in each tier network, and introducing hybrid-duplex for
different tier networks improves the heterogenous network throughput.Comment: 13 pages, 10 figures, to appear in IEEE Transactions on Wireless
Communication
Successive Interference Cancellation in Heterogeneous Cellular Networks
At present, operators address the explosive growth of mobile data demand by
densification of the cellular network so as to reduce the transmitter-receiver
distance and to achieve higher spectral efficiency. Due to such network
densification and the intense proliferation of wireless devices, modern
wireless networks are interference-limited, which motivates the use of
interference mitigation and coordination techniques. In this work, we develop a
statistical framework to evaluate the performance of multi-tier heterogeneous
networks with successive interference cancellation (SIC) capabilities,
accounting for the computational complexity of the cancellation scheme and
relevant network related parameters such as random location of the access
points (APs) and mobile users, and the characteristics of the wireless
propagation channel. We explicitly model the consecutive events of canceling
interferers and we derive the success probability to cancel the n-th strongest
signal and to decode the signal of interest after n cancellations. When users
are connected to the AP which provides the maximum average received signal
power, the analysis indicates that the performance gains of SIC diminish
quickly with n and the benefits are modest for realistic values of the
signal-to-interference ratio (SIR). We extend the statistical model to include
several association policies where distinct gains of SIC are expected: (i)
minimum load association, (ii) maxi- mum instantaneous SIR association, and
(iii) range expansion. Numerical results show the effectiveness of SIC for the
considered association policies. This work deepens the understanding of SIC by
defining the achievable gains for different association policies in multi-tier
heterogeneous networks.Comment: submitted for journal publication, 13 pages, 6 figure
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