7,541 research outputs found
Enhancing coverage and reducing power consumption in peer-to-peer networks through airborne relaying
Sub-6GHz Assisted MAC for Millimeter Wave Vehicular Communications
Sub-6GHz vehicular communications (using DSRC, ITS-G5 or C-V2X) have been
developed to support active safety applications. Future connected and automated
driving applications can require larger bandwidth and higher data rates than
currently supported by sub-6GHz V2X technologies. This has triggered the
interest in developing mmWave vehicular communications. However, solutions are
necessary to solve the challenges resulting from the use of high-frequency
bands and the high mobility of vehicles. This paper contributes to this active
research area by proposing a sub-6GHz assisted mmWave MAC that decouples the
mmWave data and control planes. The proposal offloads mmWave MAC control
functions (beam alignment, neighbor identification and scheduling) to a
sub-6GHz V2X technology, and reserves the mmWave channel for the data plane.
This approach improves the operation of the MAC as the control functions
benefit from the longer range, and the broadcast and omnidirectional
transmissions of sub-6GHz V2X technologies. This simulation study demonstrates
that the proposed sub-6GHz assisted mmWave MAC reduces the control overhead and
delay, and increases the spatial sharing compared to a mmWave-only
configuration (IEEE 802.11ad tailored to vehicular networks). The proposed MAC
is here evaluated for V2V communications using 802.11p for the control plane
and 802.11ad for the data plane. However, the proposal is not restricted to
these technologies, and can be adapted to other technologies such as C-V2X and
5G NR.Comment: 8 pages, 5 figure
Energy efficient scheme to Jointly Optimize Coverage and Connectivity in Large Scale Wireless Sensor Network
Efficient coverage and connectivity are two important factors that ensures better service quality especially during tracking targets or monitoring events in wireless sensor network. Although massive amount of studies has been carried out in the past to enhance coverage and connectivity issues, till date very few studies have witnessed a significant and standard outcomes that can opt further. Hence, this paper introduces a computationally efficient technique for jointly addressing both coverage and connectivity problems in large-scale wireless sensor network that ensures optimal network lifetime too. The proposed system has been empirically designed, and algorithms formulated to ensure energy efficient monitoring of event. The outcomes of the study are compared with standard energy efficient hierarchical protocol to benchmark the results
Coverage Protocols for Wireless Sensor Networks: Review and Future Directions
The coverage problem in wireless sensor networks (WSNs) can be generally
defined as a measure of how effectively a network field is monitored by its
sensor nodes. This problem has attracted a lot of interest over the years and
as a result, many coverage protocols were proposed. In this survey, we first
propose a taxonomy for classifying coverage protocols in WSNs. Then, we
classify the coverage protocols into three categories (i.e. coverage aware
deployment protocols, sleep scheduling protocols for flat networks, and
cluster-based sleep scheduling protocols) based on the network stage where the
coverage is optimized. For each category, relevant protocols are thoroughly
reviewed and classified based on the adopted coverage techniques. Finally, we
discuss open issues (and recommend future directions to resolve them)
associated with the design of realistic coverage protocols. Issues such as
realistic sensing models, realistic energy consumption models, realistic
connectivity models and sensor localization are covered
Millimeter Wave Cellular Networks: A MAC Layer Perspective
The millimeter wave (mmWave) frequency band is seen as a key enabler of
multi-gigabit wireless access in future cellular networks. In order to overcome
the propagation challenges, mmWave systems use a large number of antenna
elements both at the base station and at the user equipment, which lead to high
directivity gains, fully-directional communications, and possible noise-limited
operations. The fundamental differences between mmWave networks and traditional
ones challenge the classical design constraints, objectives, and available
degrees of freedom. This paper addresses the implications that highly
directional communication has on the design of an efficient medium access
control (MAC) layer. The paper discusses key MAC layer issues, such as
synchronization, random access, handover, channelization, interference
management, scheduling, and association. The paper provides an integrated view
on MAC layer issues for cellular networks, identifies new challenges and
tradeoffs, and provides novel insights and solution approaches.Comment: 21 pages, 9 figures, 2 tables, to appear in IEEE Transactions on
Communication
Cooperative network-coding system for wireless sensor networks
Describes a cooperative network coding system for wireless sensor networks. In this paper, we propose two practical power) and bandwidth)efficient systems based on amplify)and)forward (AF) and decode)and)forward (DF) schemes to address the problem of information exchange via a relay. The key idea is to channel encode each source’s message by using a high)performance non)binary turbo code based on Partial Unit Memory (PUM) codes to enhance the bit)error)rate performance, then reduce the energy consumption and increase spectrum efficiency by using network coding (NC) to combine individual nodes’ messages at the relay before forwarding to the destination. Two simple and low complexity physical layer NC schemes are proposed based on combinations of received source messages at the relay. We also present the theoretical limits and numerical analysis of the proposed schemes. Simulation results under Additive White Gaussian Noise, confirm that the proposed schemes achieve significant bandwidth savings and fewer transmissions over the benchmark systems which do not resort to NC. Theoretical limits for capacity and Signal to Noise Ratio behaviour for the proposed schemes are derived. The paper also proposes a cooperative strategy that is useful when insufficient combined messages are received at a node to recover the desired source messages, thus enabling the system to retrieve all packets with significantly fewer retransmission request messages
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