| 1. |
- Balador, Ali, et al.
(författare)
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A Density-Based Contention Window Control Scheme for Unicast Communications in Vehicular Ad Hoc Networks
- 2015
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Ingår i: International Journal of Ad Hoc and Ubiquitous Computing. - 1743-8225 .- 1743-8233. ; 24, s. 65-75
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Tidskriftsartikel (refereegranskat)abstract
- Achieving a well-designed medium access control MAC protocol is a challenging issue to improve communications efficiency due to the dynamic nature of vehicular ad hoc networks VANETs. IEEE 802.11p standard was selected as the best choice for vehicular environments considering its availability, maturity, and cost. The common problem in all IEEE 802.11 based protocols is scalability, exhibiting performance degradation in highly variable network scenarios. Experimental results for the IEEE 802.11-based MAC protocol show the importance of contention window adjustment on communications performance; however the vehicular communications community has not yet addressed this issue in unicast communication environments. This paper proposes a novel contention window control scheme for VANET environments based on estimating the network density, which is then used to dynamically adapt the CW size. Analysis and simulation results show that our proposal provides better overall performance compared with previous proposals, even in high network density scenarios.
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| 2. |
- Balador, Ali, et al.
(författare)
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A Novel 802.11 Contention Window Control Scheme for Vehicular Environments
- 2013
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Ingår i: Jornadas Sarteco 2013 JS 2013. - 9788469583302 ; , s. 98-103
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Konferensbidrag (refereegranskat)abstract
- Intelligent Transportation Systems (ITS) have attractive potential in order to decrease the ordi- nary traffic jams and avoid transportation disasters. Also, they are able to provide various infotainment services like browsing, reading e-mail or using social networks that makes a trip more interesting. In or- der to make it more efficient in real vehicular envi- ronments, achieving a well-designed Medium Access Control (MAC) protocol is a challenging issue due to the dynamic nature of VANETs, scalability issues, and the variety of application requirements. Differ- ent standardization organizations have selected IEEE 802.11 as the first choice for VANET environments considering its availability, maturity, and cost. The research results for IEEE 802.11 MAC protocol show the importance of contention window adjustment on the communications performance. The impact of ad- justing the contention window has been studied in MANETs, but the vehicular communication commu- nity has not yet addressed this issue thoroughly. This paper proposes e-HBCWC, a new contention window control scheme for VANET environments based on estimating the network condition. Analy- sis and simulation results using OMNeT++ in urban scenarios show that e-HBCWC clearly outperforms 802.11 DCF, even in very high network density, by increasing the packet delivery rate while decreasing the number of collisions and the end-to-end delay for unicast applications.
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| 3. |
- Balador, Ali, et al.
(författare)
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An Efficient MAC Protocol for vehicle platooning in automated highway systems
- 2015
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Ingår i: Jornadas Sarteco 2015 JS 2015. - Cordoba, Spain.
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Konferensbidrag (refereegranskat)abstract
- Lately, all the top truck manufacturers are investing considerable resources in the research and development of platooning systems which would allow vehicles to save fuel and improve safety by travelling in a close-following manner. The platooning system requires frequent and reliable vehicle-to-vehicle communications. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if re-transmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability considerably compared to pure 802.11p.
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| 4. |
- Balador, Ali, et al.
(författare)
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Congestion Control for Vehicular Environments by Adjusting IEEE 802.11 Contention Window Size
- 2013
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Ingår i: 13th International Conference on Algorithms and Architectures for Parallel Processing ICA3PP-2013. - Cham : Springer International Publishing. - 9783319038889 ; , s. 259-266
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Konferensbidrag (refereegranskat)abstract
- Medium access control protocols should manage the highly dynamic nature of Vehicular Ad Hoc Networks (VANETs) and the variety of application requirements. Therefore, achieving a well-designed MAC protocol in VANETs is a challenging issue. The contention window is a critical element for handling medium access collisions in IEEE 802.11, and it highly affects the communications performance. This paper proposes a new contention window control scheme, called DBM-ACW, for VANET environments. Analysis and simulation results using OMNeT++ in urban scenarios show that DBM-ACW provides better overall performance compared with previous proposals, even with high network densities.
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| 5. |
- Balador, Ali, et al.
(författare)
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DTB-MAC : Dynamic Token-Based MAC Protocol for Reliable and Efficient Beacon Broadcasting in VANETs
- 2016
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Ingår i: The 13th Annual IEEE Consumer Communications & Networking Conference CCNC 2016. - 9781479963904 ; , s. 109-114
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Konferensbidrag (refereegranskat)abstract
- Most applications developed for vehicular environments rely on broadcasting as the main mechanism to disseminate their messages. However, in IEEE 802.11p, which is the most widely accepted Medium Access Control (MAC) protocol for vehicular communications, all transmissions remain unacknowledged if broadcasting is used. Furthermore, safety message transmission requires a strict delay limit and a high reliability, which is an issue for random access MAC protocols like IEEE 802.11p. Therefore, transmission reliability becomes the most important issue for broadcast-based services in vehicular environments. In this paper, we propose a hybrid MAC protocol, referred as Dynamic Token-Based MAC Protocol (DTB-MAC). DTB-MAC uses both a token passing mechanism and a random access MAC protocol to prevent channel contention as much as possible, and to improve the reliability of safety message transmissions. Our proposed protocol tries to select the best neighbouring node as the next transmitter, and when it is not possible, or when it causes a high overhead, the random access MAC protocol is used instead. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance compared with IEEE 802.11p in terms of channel utilization and beacon delivery ratio.
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| 6. |
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| 7. |
- Balador, Ali, et al.
(författare)
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Reducing Channel Contention in Vehicular Environments Through an Adaptive Contention Window Solution
- 2013
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Ingår i: IFIP Wireless Days WD 2013. - 9781479905430
-
Konferensbidrag (refereegranskat)abstract
- Intelligent Transportation Systems (ITS) are attracting growing attention both in industry and academia due to the advances in wireless communication technologies, and a significant demand for a wide variety of applications targeting this kind of environments are expected. In order to make it usable in real vehicular environments, achieving a well-designed Medium Access Control (MAC) protocol is a challenging issue due to the dynamic nature of Vehicular Ad Hoc Networks (VANETs), scalability issues, and the variety of application requirements. Different standardization organizations have selected IEEE 802.11 as the first choice for VANET environments considering its availability, maturity, and cost. The contention window is a critical parameter for handling medium access collisions by the IEEE 802.11 MAC protocol, and it highly affects the communications performance. The impact of adjusting the contention window has been studied in Mobile Ad-Hoc Networks (MANETs), but the vehicular communications community has not yet addressed this issue thoroughly. This paper proposes a new contention window control scheme, called DBM-ACW, for VANET environments. Analysis and simulation results using OMNeT++ in a highway scenario show that DBM-ACW provides better overall performance compared with previous proposals, even with high network densities.
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| 8. |
- Imran, Muhammad A., et al.
(författare)
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Exploring the Boundaries of Connected Systems: Communications for Hard-to-Reach Areas and Extreme Conditions
- 2024
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Ingår i: Proceedings of the IEEE. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9219 .- 1558-2256.
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Tidskriftsartikel (refereegranskat)abstract
- Cellular communication standards have been established to ensure connectivity across most urban environments, complemented by deployment hardware and facilities tailored for city life. At the same time, numerous initiatives seek to broaden connectivity to rural and developing areas. However, with nearly half the global population still offline, there is an urgent need to drive research toward enhancing connectivity in areas and conditions that deviate from the norm. This article delves into innovative communication solutions not only for hard-to-reach and extreme environments but also introduces “hard-to-serve” areas as a crucial, yet underexplored, category within the broader spectrum of connectivity challenges.We explore the latest advancements in communication systems designed for environments subject to extreme temperatures, harsh weather, excessive dust, or even disasters such as fires. Our exploration spans the entire communication stack, covering communications on isolated islands, sparsely populated regions, mountainous terrains, and even underwater and underground settings. We highlight system architectures, hardware, materials, algorithms, and other pivotal technologies that promise to connect these challenging areas. Through case studies, we explore the application of 5G for innovative research, long range (LoRa) for audio messages and emails, LoRa wireless connections, free-space optics, communications in underwater and underground scenarios, delay-tolerant networks, satellite links, and the strategic use of shared spectrum and TV white space (TVWS) to improve mobile connectivity in secluded and remote regions. These studies also touch on prevalent challenges such as power outages, regulatory gaps, technological availability, and human resource constraints, where we introduce the concept of peri-urban hard-to-serve areas where populations might struggle with affordability or lack the skills for traditional connectivity solutions. This article provides an exhaustive summary of our research, showcasing how 6G and future networks will play a crucial role in delivering connectivity to areas that are hard-to-reach, hard-to-serve, or subject to extreme conditions (ECs).
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| 9. |
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| 10. |
- Manzoni, Pietro, et al.
(författare)
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Crowdsourcing Through TinyML as aWay to Engage End-Users in IoT Solutions
- 2023. - 1
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Ingår i: Mobile Crowdsourcing. - Switzerland : Springer. - 9783031323973 - 9783031323966 ; , s. 359-387
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This book offers the latest research results in recent development on the principles, techniques and applications in mobile crowdsourcing. It presents state-of-the-art content and provides an in-depth overview of the basic background in this related field. Crowdsourcing involves a large crowd of participants working together to contribute or produce goods and services for the society. The early 21st century applications of crowdsourcing can be called crowdsourcing 1.0, which includes businesses using crowdsourcing to accomplish various tasks, such as the ability to offload peak demand, access cheap labor, generate better results in a timely matter, and reach a wider array of talent outside the organization. Mobile crowdsensing can be described as an extension of crowdsourcing to the mobile network to combine the idea of crowdsourcing with the sensing capacity of mobile devices. As a promising paradigm for completing complex sensing and computation tasks, mobile crowdsensing serves the vital purpose of exploiting the ubiquitous smart devices carried by mobile users to make conscious or unconscious collaboration through mobile networks. Considering that we are in the era of mobile internet, mobile crowdsensing is developing rapidly and has great advantages in deployment and maintenance, sensing range and granularity, reusability, and other aspects. Due to the benefits of using mobile crowdsensing, many emergent applications are now available for individuals, business enterprises, and governments. In addition, many new techniques have been developed and are being adopted.
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