1,196 research outputs found
Energy-Optimum Throughput and Carrier Sensing Rate in CSMA-Based Wireless Networks
Cataloged from PDF version of article.We propose a model for the energy consumption of a node as a function of its throughput in a wireless CSMA network. We first model a single-hop network, and then a multi-hop network. We show that operating the CSMA network at a high throughput is energy inefficient since unsuccessful carrier sensing attempts increase the energy consumption per transmitted bit. Operating the network at a low throughput also causes energy inefficiency because of increased sleeping duration. Achieving a balance between these two opposite operating regimes, we derive the energy-optimum carrier-sensing rate and the energy-optimum throughput which maximize the number of transmitted bits for a given energy budget. For the single-hop case, we show that the energy-optimum total throughput increases as the number of nodes sharing the channel increases. For the multi-hop case, we show that energy-optimum throughput decreases as the degree of the conflict graph corresponding to the network increases. For both cases, the energy-optimum throughput reduces as the power required for carrier-sensing increases. The energy-optimum throughput is also shown to be substantially lower than the maximum throughput and the gap increases as the degree of the conflict graph increases for multi-hop networks. © 2002-2012 IEEE
Performance analysis of the carrier-sense multiple access protocol for future generation wireless networks
Ankara : The Department of Electrical and Electronics Engineering and the Graduate School of Engineering and Science of Bilkent University, 2013.Thesis (Ph. D.) -- Bilkent University, 2013.Includes bibliographical references leaves 115-127.Variants of the carrier-sense multiple access (CSMA) protocol has been employed
in many communications protocols such as the IEEE 802.11 and Ethernet standards.
CSMA based medium access control (MAC) mechanisms have been recently
proposed for other communications scenarios such as sensor networks and
acoustical underwater networks. Despite its widespread use, the performance
of the CSMA protocol is not well-studied from the perspective of these newly
encountered networking scenarios. We here investigate the performance of the
CSMA protocol from the point of three different aspects: throughput in networks
with large propagation delay, short-term fairness for delay sensitive applications
in large networks and energy efficiency-throughput trade-off in networks with
battery operated devices.
Firstly, we investigate the performance of the CSMA protocol for channels
with large propagation delay. Such channels are recently encountered in underwater
acoustic networks and in terrestrial wireless networks covering larger areas.
However, a mathematical model of CSMA performance in such networks is not
known. We propose a semi-Markov model for a 2-node CSMA channel and then
extend this model for arbitrary number of users. Using this model, we obtain the
optimum symmetric probing rate that achieves the maximum network throughput
as a function of the average propagation delay, ¯d, and the number of nodes
sharing the channel, N. The proposed model predicts that the total capacity
decreases with ¯d
−1 as N goes to infinity when all nodes probe the channel at the
optimum rate. The optimum probing rate for each node decreases with 1/N and
the total optimum probing rate decreases faster than ¯d
−1 as N goes to infinity.
Secondly, we investigate whether the short-term fairness of a large CSMA network degrades with the network size and density. Our results suggest that (a)
the throughput region that can be achieved within the acceptable limits of shortterm
fairness reduces as the number of contending neighboring nodes increases for
random regular conflict graphs, (b) short-term fair capacity weakly depends on
the network size for a random regular conflict graph but a stronger dependence is
observed for a grid topology. We also present related results from the statistical
physics literature on long-range correlations in large systems and point out the
relation between these results and short-term fairness of CSMA systems.
Thirdly, we investigate the energy efficiency of a CSMA network proposing a
model for the energy consumption of a node as a function of its throughput. We
show that operating the CSMA network at a very high or at a very low throughput
is energy inefficient because of increasing carrier-sensing and sleeping costs, respectively.
Achieving a balance between these two opposite operating regimes, we
derive the energy-optimum carrier-sensing rate and the energy-optimum throughput
which maximize the number of transmitted bits for a given energy budget. For
the single-hop case, we show that the energy-optimum total throughput increases
as the number of nodes sharing the channel increases. For the multi-hop case, we
show that the energy-optimum throughput decreases as the degree of the conflict
graph of the network increases. For both cases, the energy-optimum throughput
reduces as the power required for carrier-sensing increases. The energy-optimum
throughput is also shown to be substantially lower than the maximum throughput
and the gap increases as the degree of the conflict graph increases for multi-hop
networks.Köseoğlu, MehmetPh.D
Fair Coexistence of Scheduled and Random Access Wireless Networks: Unlicensed LTE/WiFi
We study the fair coexistence of scheduled and random access transmitters
sharing the same frequency channel. Interest in coexistence is topical due to
the need for emerging unlicensed LTE technologies to coexist fairly with WiFi.
However, this interest is not confined to LTE/WiFi as coexistence is likely to
become increasingly commonplace in IoT networks and beyond 5G. In this article
we show that mixing scheduled and random access incurs and inherent
throughput/delay cost, the cost of heterogeneity. We derive the joint
proportional fair rate allocation, which casts useful light on current LTE/WiFi
discussions. We present experimental results on inter-technology detection and
consider the impact of imperfect carrier sensing.Comment: 14 pages, 8 figures, journa
Goodbye, ALOHA!
©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The vision of the Internet of Things (IoT) to interconnect and Internet-connect everyday people, objects, and machines poses new challenges in the design of wireless communication networks. The design of medium access control (MAC) protocols has been traditionally an intense area of research due to their high impact on the overall performance of wireless communications. The majority of research activities in this field deal with different variations of protocols somehow based on ALOHA, either with or without listen before talk, i.e., carrier sensing multiple access. These protocols operate well under low traffic loads and low number of simultaneous devices. However, they suffer from congestion as the traffic load and the number of devices increase. For this reason, unless revisited, the MAC layer can become a bottleneck for the success of the IoT. In this paper, we provide an overview of the existing MAC solutions for the IoT, describing current limitations and envisioned challenges for the near future. Motivated by those, we identify a family of simple algorithms based on distributed queueing (DQ), which can operate for an infinite number of devices generating any traffic load and pattern. A description of the DQ mechanism is provided and most relevant existing studies of DQ applied in different scenarios are described in this paper. In addition, we provide a novel performance evaluation of DQ when applied for the IoT. Finally, a description of the very first demo of DQ for its use in the IoT is also included in this paper.Peer ReviewedPostprint (author's final draft
Life-Add: Lifetime Adjustable Design for WiFi Networks with Heterogeneous Energy Supplies
WiFi usage significantly reduces the battery lifetime of handheld devices
such as smartphones and tablets, due to its high energy consumption. In this
paper, we propose "Life-Add": a Lifetime Adjustable design for WiFi networks,
where the devices are powered by battery, electric power, and/or renewable
energy. In Life-Add, a device turns off its radio to save energy when the
channel is sensed to be busy, and sleeps for a random time period before
sensing the channel again. Life-Add carefully controls the devices' average
sleep periods to improve their throughput while satisfying their operation time
requirement. It is proven that Life-Add achieves near-optimal proportional-fair
utility performance for single access point (AP) scenarios. Moreover, Life-Add
alleviates the near-far effect and hidden terminal problem in general multiple
AP scenarios. Our ns-3 simulations show that Life-Add simultaneously improves
the lifetime, throughput, and fairness performance of WiFi networks, and
coexists harmoniously with IEEE 802.11.Comment: This is the technical report of our WiOpt paper. The paper received
the best student paper award at IEEE WiOpt 2013. The first three authors are
co-primary author
Proportional fairness in wireless powered CSMA/CA based IoT networks
This paper considers the deployment of a hybrid wireless data/power access
point in an 802.11-based wireless powered IoT network. The proportionally fair
allocation of throughputs across IoT nodes is considered under the constraints
of energy neutrality and CPU capability for each device. The joint optimization
of wireless powering and data communication resources takes the CSMA/CA random
channel access features, e.g. the backoff procedure, collisions, protocol
overhead into account. Numerical results show that the optimized solution can
effectively balance individual throughput across nodes, and meanwhile
proportionally maximize the overall sum throughput under energy constraints.Comment: Accepted by Globecom 201
Virtual sensing directional hub MAC (VSDH-MAC) protocol with power control
Medium access control (MAC) protocols play a vital role in making effective use of a multiple access channel as it governs the achievable performance such as channel utilization and corresponding quality of service of wireless sensor networks (WSNs). In this paper, a virtual carrier sensing directional hub (VSDH) MAC protocol incorporating realistic directional antenna patterns is proposed for directional single hub centralized WSNs. While in most instances, MAC protocols assume idealized directional antenna patterns, the proposed VSDH-MAC protocol incorporates realistic directional antenna patterns to deliver enhanced link performance. We demonstrate that the use of directional antennas with a suitable MAC protocol can provide enhanced communication range and increased throughput with reduced energy consumption at each node, compared to the case when only omnidirectional antennas are used. For the scenarios considered in this study, results show that the average transmit power of the sensor nodes can be reduced by a factor of two, and at the same time offer significantly extended lifetime
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
Fair coexistence of scheduled and random access wireless networks: unlicensed LTE/WiFi
We study the fair coexistence of scheduled and random access transmitters sharing the same frequency channel. Interest in coexistence is topical due to the need for emerging unlicensed LTE technologies to coexist fairly withWiFi. However, this interest is not confined to LTE/WiFi as coexistence is likely to become increasingly commonplace in IoT networks and beyond 5G. In this paper, we show that mixing scheduled and random access incurs an inherent throughput/delay cost and the cost of heterogeneity. We derive the joint proportional fair rate allocation, which casts useful light on current LTE/WiFi discussions. We present experimental results on inter-technology detection and consider the impact of imperfect carrier sensing.This work was supported in part by the Science Foundation Ireland under Grant 11/PI/1177 and Grant 13/RC/207, in part by the European Commission in the framework of the H2020-ICT-2014-2 Project Flex5Gware under Grant 671563, and in part by the Spanish Ministry of Economy and the FEDER regional development fund through SINERGIA Project under Grant TEC2015-71303-R
- …