13,617 research outputs found
Multi-Hop Cluster based IEEE 802.11p and LTE Hybrid Architecture for VANET Safety Message Dissemination
This paper proposes a hybrid architecture, namely VMaSC-LTE, combining IEEE
802.11p based multi-hop clustering and the fourth generation cellular system,
Long Term Evolution (LTE), with the goal of achieving high data packet delivery
ratio and low delay while keeping the usage of the cellular architecture at the
minimum level. In VMaSC-LTE, vehicles are clustered based on a novel approach
named VMaSC: Vehicular Multi-hop algorithm for Stable Clustering. From the
clustered topology, elected cluster heads operate as dual-interface nodes with
the functionality of IEEE 802.11p and LTE interface to link VANET to LTE
network. Using various key metrics of interest including data packet delivery
ratio, delay, control overhead and clustering stability, we demonstrate
superior performance of the proposed architecture compared to both previously
proposed hybrid architectures and alternative routing mechanisms including
flooding and cluster based routing via extensive simulations in ns-3 with the
vehicle mobility input from the Simulation of Urban Mobility (SUMO). The
proposed architecture also allows achieving higher required reliability of the
application quantified by the data packet delivery ratio at the cost of higher
LTE usage determined by the number of cluster heads in the network.Comment: 16 pages, 13 figures, 7 tables, journal,transactions on vehicular
technolog
Over-the-air Signaling in Cellular Networks: An Overview
To improve the capacity and coverage of current cellular networks, many
advanced technologies such as massive MIMO, inter-cell coordination, small
cells, device-to-device communications, and so on, are under studying. Many
proposed techniques have been shown to offer significant performance
improvement. Thus, the enabler of those techniques is of great importance. That
is the necessary signaling which guarantee the operation of those techniques.
The design and transmission of those signaling, especially the over-the-air
(OTA) signaling, is challenging. In this article, we provide an overview of the
OTA signaling in cellular networks to provide insights on the design of OTA
signaling. Specifically, we first give a brief introduction of the OTA
signaling in long term evolution (LTE), and then we discuss the challenges and
requirements in designing the OTA signaling in cellular networks in detail. To
better understand the OTA signaling, we give two important classifications of
OTA signaling and address their properties and applications. Finally, we
propose a signature-based signaling named (single-tone signaling, STS) which
can be used for inter-cell OTA signaling and is especially useful and robust in
multi-signal scenario. Simulation results are given to compare the detection
performance of different OTA signaling.Comment: 8 page
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
Feasibility of 5G mm-wave communication for connected autonomous vehicles
The internet-of-things (IoT) environment holds different intelligent
components networked together and will enable seamless data communication
between the connected components. Connected autonomous vehicles or CAVs are
major components of the IoT, and the smooth, reliable, and safe operation of
CAVs demands a reliable wireless communication system, which can ensure high
connectivity, high throughput and low communication latency. The 5G
millimeter-wave or mm-wave communication network offers such benefits, which
can be the enabler of CAVs, especially for dense congested areas. In this
research, we have evaluated the 5G mm-wave and Dedicated Short Range
Communication (DSRC) for different CAV applications in a Network Simulator-3
(ns-3). For the CAV applications, we have evaluated the end-to-end latency,
packet loss, and data rate (for both the CAV receiver and transmitter) of the
5G mm-wave. We have found that 5G mm-wave can support CAV safety applications
by ensuring lower latency compared to the required minimum latency of 200
milliseconds for the forward collision warning application. For mobility
applications, we have found that 5G mm-wave can support multiple CAVs with a
high data receive rate, which is enough for real-time high definition video
streaming for in-vehicle infotainment, with mean packet delay of 13
milliseconds. The findings from this study establish that 5G mm-wave can be the
enabler of future CAVs in congested areas. Using the evaluation framework
developed in this paper, public agencies can evaluate 5G mm-wave to support
CAVs in congested areas, such as heavy pedestrian areas like downtown,
commercial zones, under their jurisdiction.Comment: 16 pages, 3 tables, 6 figure
Aerial-Terrestrial Communications: Terrestrial Cooperation and Energy-Efficient Transmissions to Aerial-Base Stations
Hybrid aerial-terrestrial communication networks based on Low Altitude
Platforms (LAPs) are expected to optimally meet the urgent communication needs
of emergency relief and recovery operations for tackling large scale natural
disasters. The energy-efficient operation of such networks is important given
the fact that the entire network infrastructure, including the battery operated
ground terminals, exhibits requirements to operate under power-constrained
situations. In this paper, we discuss the design and evaluation of an adaptive
cooperative scheme intended to extend the survivability of the battery operated
aerial-terrestrial communication links. We propose and evaluate a real-time
adaptive cooperative transmission strategy for dynamic selection between direct
and cooperative links based on the channel conditions for improved energy
efficiency. We show that the cooperation between mobile terrestrial terminals
on the ground could improve the energy efficiency in the uplink depending on
the temporal behavior of the terrestrial and the aerial uplink channels. The
corresponding delay in having cooperative (relay-based) communications with
relay selection is also addressed. The simulation analysis corroborates that
the adaptive transmission technique improves the overall energy efficiency of
the network whilst maintaining low latency enabling real time applications.Comment: To Appear In IEEE Transactions On Aerospace And Electronic Systems,
201
Power-Aware Hybrid Intrusion Detection System (PHIDS) using Cellular Automata in Wireless AdHoc Networks
Adhoc wireless network with their changing topology and distributed nature
are more prone to intruders. The network monitoring functionality should be in
operation as long as the network exists with nil constraints. The efficiency of
an Intrusion detection system in the case of an adhoc network is not only
determined by its dynamicity in monitoring but also in its flexibility in
utilizing the available power in each of its nodes. In this paper we propose a
hybrid intrusion detection system, based on a power level metric for potential
adhoc hosts, which is used to determine the duration for which a particular
node can support a network monitoring node. Power aware hybrid intrusion
detection system focuses on the available power level in each of the nodes and
determines the network monitors. Power awareness in the network results in
maintaining power for network monitoring, with monitors changing often, since
it is an iterative power optimal solution to identify nodes for distributed
agent based intrusion detection. The advantage that this approach entails is
the inherent flexibility it provides, by means of considering only fewer nodes
for reestablishing network monitors. The detection of intrusions in the network
is done with the help of Cellular Automat CA. The CAs classify a packet routed
through the network either as normal or an intrusion. The use of CAs enable in
the identification of already occurred intrusions as well as new intrusions
Delay Analysis of Spatially-Coded MIMO-ZFBF with Retransmissions in Random Networks
For a low-mobile Poisson bipolar network and under
line-of-sight/non-line-of-sight (LOS/NLOS) path-loss model, we study repetitive
retransmissions (RR) and blocked incremental redundancy (B-IR). We consider
spatially-coded multiple-input multiple-output (MIMO) zero-forcing beamforming
(ZFBF) multiplexing system, whereby the packet success reception is determined
based on the aggregate data rate across spatial dimensions of the MIMO system.
Characterization of retransmission performance in this low-mobile configuration
is practically important, but inherently complex due to a substantial rate
correlation across retransmissions and intractability of evaluating the
probability density function (pdf) of aggregate data rate. Adopting tools of
stochastic geometry, we firstly characterize the rate correlation coefficient
(RCC) for both schemes. Our results show that, compared to RR scheme, B-IR
scheme has higher RCC while its coverage probability is substantially larger.
We demonstrate that the spotted contention between coverage probability and RCC
causes the mean transmission delay (MTD) of B-IR to become either smaller or
larger than the MTD of RR scheme. Finally, we develop a numerical approximation
of MTD, and evaluate the effective spatial throughput (EST), which is
reciprocal to MTD, of RR and B-IR schemes. Our numerical results highlight
fundamental tradeoffs between densification, multiplexing gain, block length,
and activity factor of nodes. We further observe that for dense networks 1) LOS
component is considerably instrumental to enhance EST; 2) EST of B-IR scheme
can be much higher than that of RR scheme; 3) When Doppler spread exists, it
can improve MTD of B-IR while it does not cast any meaningful effect on the MTD
of RR.Comment: 16 page
Enhanced capacity & coverage by Wi-Fi LTE Integration
Wi-Fi provides cost-effective data capacity at hotspots in conjunction with
broadband cellular networks. The hotspots are required to capture a large
number of users and provide high data rates. Data rates, over the Wi-Fi
interface, are influenced by the media access protocol, which loses throughput
due to delays and unintended collisions when a large number of users are
active. The hotspot range which determines the number of users, that can
associate, is limited by the lower power of the client rather than the access
point. By diverting the traffic destined to the access point via another access
network, both range and efficiency can be improved. This uplink redirection or
diversion is achieved by simultaneous use of the Wi-Fi and LTE radio
interfaces. Three options - loose, tight, and hybrid integration are presented
towards providing enhanced capacity and coverage.Comment: Submitted as a candidate article for IEEE Communications Magazine,
Topic: The Future of Wi-Fi (November 2014
A Lyapunov Optimization Approach for Green Cellular Networks with Hybrid Energy Supplies
Powering cellular networks with renewable energy sources via energy
harvesting (EH) has recently been proposed as a promising solution for green
networking. However, with intermittent and random energy arrivals, it is
challenging to provide satisfactory quality of service (QoS) in EH networks. To
enjoy the greenness brought by EH while overcoming the instability of the
renewable energy sources, hybrid energy supply (HES) networks that are powered
by both EH and the electric grid have emerged as a new paradigm for green
communications. In this paper, we will propose new design methodologies for HES
green cellular networks with the help of Lyapunov optimization techniques. The
network service cost, which addresses both the grid energy consumption and
achievable QoS, is adopted as the performance metric, and it is optimized via
base station assignment and power control (BAPC). Our main contribution is a
low-complexity online algorithm to minimize the long-term average network
service cost, namely, the Lyapunov optimization-based BAPC (LBAPC) algorithm.
One main advantage of this algorithm is that the decisions depend only on the
instantaneous side information without requiring distribution information of
channels and EH processes. To determine the network operation, we only need to
solve a deterministic per-time slot problem, for which an efficient inner-outer
optimization algorithm is proposed. Moreover, the proposed algorithm is shown
to be asymptotically optimal via rigorous analysis. Finally, sample simulation
results are presented to verify the theoretical analysis as well as validate
the effectiveness of the proposed algorithm.Comment: 15 pages, 8 figures, to appear in IEEE Journal on Selected Areas in
Communication
A Multi-Scale Spatiotemporal Perspective of Connected and Automated Vehicles: Applications and Wireless Networking
Wireless communication is a basis of the vision of connected and automated
vehicles (CAVs). Given the heterogeneity of both wireless communication
technologies and CAV applications, one question that is critical to technology
road-mapping and policy making is which communication technology is more
suitable for a specific CAV application. Focusing on the technical aspect of
this question, we present a multi-scale spatiotemporal perspective of wireless
communication technologies as well as canonical CAV applications in active
safety, fuel economy and emission control, vehicle automation, and vehicular
infotainment. Our analysis shows that CAV applications in the regime of small
spatiotemporal scale communication requirements are best supported by V2V
communications, applications in the regime of large spatiotemporal scale
communication requirements are better supported by cellular communications, and
applications in the regime of small spatial scale but medium-to-large temporal
scale can be supported by both V2V and cellular communications and provide the
opportunity of leveraging heterogeneous communication resources
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