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University of Victoria

1. Khayyat, Khalid M. Jamil. Performance modelling and QoS support for wireless Ad Hoc networks.

Degree: Dept. of Electrical and Computer Engineering, 2011, University of Victoria

We present a Markov chain analysis for studying the performance of wireless ad hoc networks. The models presented in this dissertation support an arbitrary backoff strategy. We found that the most important parameter affecting the performance of binary exponential backoff is the initial backoff window size. Our experimental results show that the probability of collision can be reduced when the initial backoff window size equals the number of terminals. Thus, the throughput of the system increases and, at the same time, the delay to transmit the frame is reduced. In our second contribution, we present a new analytical model of a Medium Access Control (MAC) layer for wireless ad hoc networks that takes into account frame retry limits for a four-way handshaking mechanism. This model offers flexibility to address some design issues such as the effects of traffic parameters as well as possible improvements for wireless ad hoc networks. It effectively captures important network performance characteristics such as throughput, channel utilization, delay, and average energy. Under this analytical framework, we evaluate the effect of the Request-to-Send (RTS) state on unsuccessful transmission probability and its effect on performance particularly when the hidden terminal problem is dominant, the traffic is heavy, or the data frame length is very large. By using our proposed model, we show that the probability of collision can be reduced when using a Request-to-Send/Clear- to-Send (RTS/CTS) mechanism. Thus, the throughput increases and, at the same time, the delay and the average energy to transmit the frame decrease. In our third contribution, we present a new analytical model of a MAC layer for wireless ad hoc networks that takes into account channel bit errors and frame retry limits for a two-way handshaking mechanism. This model offers flexibility to address design issues such as the effects of traffic parameters and possible improvements for wireless ad hoc networks. We illustrate that an important parameter affecting the performance of binary exponential backoff is the initial backoff window size. We show that for a low bit error rate (BER) the throughput increases and, at the same time, the delay and the average energy to transmit the frame decrease. Results show also that the negative acknowledgment-based (NAK-based) model proves more useful for a high BER. In our fourth contribution, we present a new analytical model of a MAC layer for wireless ad hoc networks that takes into account Quality of Service (QoS) of the MAC layer for a two-way handshaking mechanism. The model includes a high priority traffic class (class 1) and a low priority traffic class (class 2). Extension of the model to more QoS levels is easily accomplished. We illustrate an important parameter affecting the performance of an Arbitration InterFrame Space (AIFS) and small backoff window size limits. They cause the frame to start contending the channel earlier and to complete the backoff sooner. As a result, the… Advisors/Committee Members: Gebali, Fayez (supervisor).

Subjects/Keywords: Markov chain analysis; backoff window; MAC layer

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Khayyat, K. M. J. (2011). Performance modelling and QoS support for wireless Ad Hoc networks. (Thesis). University of Victoria. Retrieved from http://hdl.handle.net/1828/3632

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Khayyat, Khalid M Jamil. “Performance modelling and QoS support for wireless Ad Hoc networks.” 2011. Thesis, University of Victoria. Accessed November 17, 2019. http://hdl.handle.net/1828/3632.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Khayyat, Khalid M Jamil. “Performance modelling and QoS support for wireless Ad Hoc networks.” 2011. Web. 17 Nov 2019.

Vancouver:

Khayyat KMJ. Performance modelling and QoS support for wireless Ad Hoc networks. [Internet] [Thesis]. University of Victoria; 2011. [cited 2019 Nov 17]. Available from: http://hdl.handle.net/1828/3632.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Khayyat KMJ. Performance modelling and QoS support for wireless Ad Hoc networks. [Thesis]. University of Victoria; 2011. Available from: http://hdl.handle.net/1828/3632

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Universitat Politècnica de València

2. Balador, Ali. Design and Evaluation of Efficient Medium Access Control Solutions for Vehicular Environments .

Degree: 2016, Universitat Politècnica de València

[EN] In recent years, advances in wireless technologies and improved sensing and computational capabilities have led to a gradual transition towards Intelligent Transportation Systems (ITS) and related applications. These applications aim at improving road safety, provide smart navigation, and eco-friendly driving. Vehicular Ad hoc Networks (VANETs) provide a communication structure for ITS by equipping cars with advanced sensors and communication devices that enable a direct exchange of information between vehicles. Different types of ITS applications rely on two types of messages: periodic beacons and event-driven messages. Beacons include information such as geographical location, speed, and acceleration, and they are only disseminated to a close neighborhood. Differently from beacons, event-driven messages are only generated when a critical event of general interest occurs, and it is spread within a specific target area for the duration of the event. The reliability of information exchange is one of the main issues for vehicularcommunications since the safety of people on the road is directly related to the effectiveness of these transmissions. A Medium Access Control (MAC) protocol must guarantee reliable beacon broadcasting within deadline bounds to all vehicles in the neighbourhood, thereby providing them timely notifications about unsafe driving conditions or other hazardous events. Moreover, infotainment and comfort applications require reliable unicast transmissions that must be taken into account. However, high node mobility, highly dynamic topology, and lack of a central control unit, are issues that make the design of a reliable MAC protocol for vehicular environments a very difficult and challenging task, especially when efficient broadcasting strategies are required. The IEEE 802.11p MAC protocol, an approved amendment to the IEEE 802.11 standard, is a random access protocol that is unable to provide guaranteed delay bounds with sufficient reliability in vehicular scenarios, especially under high channel usage. This problem is particularly serious when implementing (semi-) automated driving applications such as platooning, where inter-vehicle spacing is drastically reduced, and the control loop that manages and maintains the platoon requires frequent, timely and reliable exchange of status information (beacons). In this thesis novel protocols compatible with the IEEE 802.11 and 802.11p standards are proposed in order to optimally adjust the contention window size for unicast applications in Mobile Ad hoc Networks (MANETs) and VANETs. Experimental tests comparing our proposals to existing solutions show that the former are able to improve the packet delivery ratio and the average end-to-end delay for unicast applications. Concerning efficient message diffusion (broadcast) in VANET environments, we proposed token-based MAC solutions to improve the performance achieved by existing 802.11p driving safety applications in different vehicular environments, including highway, urban, and platooning… Advisors/Committee Members: Cano Escribá, Juan Carlos (advisor), Tavares de Araujo Cesariny Calafate, Carlos Miguel (advisor).

Subjects/Keywords: Vehicular Ad Hoc Networks; ITS; Mobile Ad Hoc Networks; MAC layer; IEEE 802.11; IEEE 802.11p; Contention Window; Backoff; Beacon; Platooning; Reliability; Safety Applications

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Balador, A. (2016). Design and Evaluation of Efficient Medium Access Control Solutions for Vehicular Environments . (Doctoral Dissertation). Universitat Politècnica de València. Retrieved from http://hdl.handle.net/10251/64073

Chicago Manual of Style (16th Edition):

Balador, Ali. “Design and Evaluation of Efficient Medium Access Control Solutions for Vehicular Environments .” 2016. Doctoral Dissertation, Universitat Politècnica de València. Accessed November 17, 2019. http://hdl.handle.net/10251/64073.

MLA Handbook (7th Edition):

Balador, Ali. “Design and Evaluation of Efficient Medium Access Control Solutions for Vehicular Environments .” 2016. Web. 17 Nov 2019.

Vancouver:

Balador A. Design and Evaluation of Efficient Medium Access Control Solutions for Vehicular Environments . [Internet] [Doctoral dissertation]. Universitat Politècnica de València; 2016. [cited 2019 Nov 17]. Available from: http://hdl.handle.net/10251/64073.

Council of Science Editors:

Balador A. Design and Evaluation of Efficient Medium Access Control Solutions for Vehicular Environments . [Doctoral Dissertation]. Universitat Politècnica de València; 2016. Available from: http://hdl.handle.net/10251/64073

.