3,676 research outputs found
MAC Protocols for Wireless Mesh Networks with Multi-beam Antennas: A Survey
Multi-beam antenna technologies have provided lots of promising solutions to
many current challenges faced in wireless mesh networks. The antenna can
establish several beamformings simultaneously and initiate concurrent
transmissions or receptions using multiple beams, thereby increasing the
overall throughput of the network transmission. Multi-beam antenna has the
ability to increase the spatial reuse, extend the transmission range, improve
the transmission reliability, as well as save the power consumption.
Traditional Medium Access Control (MAC) protocols for wireless network largely
relied on the IEEE 802.11 Distributed Coordination Function(DCF) mechanism,
however, IEEE 802.11 DCF cannot take the advantages of these unique
capabilities provided by multi-beam antennas. This paper surveys the MAC
protocols for wireless mesh networks with multi-beam antennas. The paper first
discusses some basic information in designing multi-beam antenna system and MAC
protocols, and then presents the main challenges for the MAC protocols in
wireless mesh networks compared with the traditional MAC protocols. A
qualitative comparison of the existing MAC protocols is provided to highlight
their novel features, which provides a reference for designing the new MAC
protocols. To provide some insights on future research, several open issues of
MAC protocols are discussed for wireless mesh networks using multi-beam
antennas.Comment: 22 pages, 6 figures, Future of Information and Communication
Conference (FICC) 2019, https://doi.org/10.1007/978-3-030-12388-8_
Fast Cell Discovery in mm-wave 5G Networks with Context Information
The exploitation of mm-wave bands is one of the key-enabler for 5G mobile
radio networks. However, the introduction of mm-wave technologies in cellular
networks is not straightforward due to harsh propagation conditions that limit
the mm-wave access availability. Mm-wave technologies require high-gain antenna
systems to compensate for high path loss and limited power. As a consequence,
directional transmissions must be used for cell discovery and synchronization
processes: this can lead to a non-negligible access delay caused by the
exploration of the cell area with multiple transmissions along different
directions.
The integration of mm-wave technologies and conventional wireless access
networks with the objective of speeding up the cell search process requires new
5G network architectural solutions. Such architectures introduce a functional
split between C-plane and U-plane, thereby guaranteeing the availability of a
reliable signaling channel through conventional wireless technologies that
provides the opportunity to collect useful context information from the network
edge.
In this article, we leverage the context information related to user
positions to improve the directional cell discovery process. We investigate
fundamental trade-offs of this process and the effects of the context
information accuracy on the overall system performance. We also cope with
obstacle obstructions in the cell area and propose an approach based on a
geo-located context database where information gathered over time is stored to
guide future searches. Analytic models and numerical results are provided to
validate proposed strategies.Comment: 14 pages, submitted to IEEE Transaction on Mobile Computin
Context Information for Fast Cell Discovery in mm-wave 5G Networks
The exploitation of the mm-wave bands is one of the most promising solutions
for 5G mobile radio networks. However, the use of mm-wave technologies in
cellular networks is not straightforward due to mm-wave harsh propagation
conditions that limit access availability. In order to overcome this obstacle,
hybrid network architectures are being considered where mm-wave small cells can
exploit an overlay coverage layer based on legacy technology. The additional
mm-wave layer can also take advantage of a functional split between control and
user plane, that allows to delegate most of the signaling functions to legacy
base stations and to gather context information from users for resource
optimization. However, mm-wave technology requires high gain antenna systems to
compensate for high path loss and limited power, e.g., through the use of
multiple antennas for high directivity. Directional transmissions must be also
used for the cell discovery and synchronization process, and this can lead to a
non-negligible delay due to the need to scan the cell area with multiple
transmissions at different directions. In this paper, we propose to exploit the
context information related to user position, provided by the separated control
plane, to improve the cell discovery procedure and minimize delay. We
investigate the fundamental trade-offs of the cell discovery process with
directional antennas and the effects of the context information accuracy on its
performance. Numerical results are provided to validate our observations.Comment: 6 pages, 8 figures, in Proceedings of European Wireless 201
Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View
Small satellite systems enable whole new class of missions for navigation,
communications, remote sensing and scientific research for both civilian and
military purposes. As individual spacecraft are limited by the size, mass and
power constraints, mass-produced small satellites in large constellations or
clusters could be useful in many science missions such as gravity mapping,
tracking of forest fires, finding water resources, etc. Constellation of
satellites provide improved spatial and temporal resolution of the target.
Small satellite constellations contribute innovative applications by replacing
a single asset with several very capable spacecraft which opens the door to new
applications. With increasing levels of autonomy, there will be a need for
remote communication networks to enable communication between spacecraft. These
space based networks will need to configure and maintain dynamic routes, manage
intermediate nodes, and reconfigure themselves to achieve mission objectives.
Hence, inter-satellite communication is a key aspect when satellites fly in
formation. In this paper, we present the various researches being conducted in
the small satellite community for implementing inter-satellite communications
based on the Open System Interconnection (OSI) model. This paper also reviews
the various design parameters applicable to the first three layers of the OSI
model, i.e., physical, data link and network layer. Based on the survey, we
also present a comprehensive list of design parameters useful for achieving
inter-satellite communications for multiple small satellite missions. Specific
topics include proposed solutions for some of the challenges faced by small
satellite systems, enabling operations using a network of small satellites, and
some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications
Surveys and Tutorial
Performance improvement of ad hoc networks using directional antennas
We investigate preventive link maintenance scheme to on-demand routing
algorithms. The scheme of creating directional link is proposed to extend the life of link
that is about to break. We see the performance improvement at network layer by using the
proposed scheme. We do a comparative performance study between omni directional and
directional antennas for DSR (On-demand routing protocol) using simulation with OPNET.
By using directional antennas, substantial gain is achieved in terms of end-to-end delay,
aggregate throughput, average data packets dropped, packet delivery ratio, and routing
overhead. The proposed scheme is general and can be used with any other on-demand
routing algorithms
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