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Distributed Multiple Access and Service Differentiation Algorithms for Wireless Networks
Umeå University, Faculty of Science and Technology, Computing Science.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Communicating over a wireless channel poses many unique challenges not found in wired communication because of the special characteristics of the wireless channel. The capacity in a wireless network is typically scarce as a result of the limited bandwidth and many distinct phenomenons, like attenuation and interference, that work destructively on the received signals.

The Medium Access Control (MAC) layer is responsible for sharing this limited resource among the users. This allocation problem should be handled by considering the Quality of Service (QoS) requirements of each user as to maximize the utility. Efficient MAC algorithms are crucial in minimizing collisions between transmissions and thus achieving high utilization of the channel.

This thesis focuses on conflict resolution and service differentiation algorithms for wireless local area networks, where there is no central control of the channel and each sender independently contends for access.

In part I, we study three approaches to improve the IEEE 802.11(e) standards with focus on QoS. In the first approach, utility functions are considered, that model application preferences, to achieve service differentiation and maximize the aggregated utility. We provide algorithms for two subsidiary problems that arise from the maximization problem, and show that a near--optimal solution is found. In the second approach a collision detection algorithm for multicast transmissions is proposed, that increases the reliability for multicast compared to the protected unicast traffic. The third approach is an improved MAC algorithm for the QoS standard IEEE 802.11e. The improved algorithm outperforms the standard and achieves close to optimal performance for large number of scenarios, which significantly reduces the need of adjusting the contention parameters.

In part II, we focus on channel bursting protocols that use noise bursts to resolve channel conflicts. These protocols is capable of achieving very low collision probability. We propose two new bursting protocols, that achieve very high channel utilization, and show that the bursting technique has good fairness properties and provides efficient support for service differentiation. We also show that it is possible to reduce the number of bursts without loosing performance.

In part III, the optimal backoff distribution that minimizes the collision probability is derived. We then propose a heuristic backoff distribution with similar properties that yields high channel utilization. An extension for service differentiation is provided where the sizes of the backoff windows are adjusted.

Place, publisher, year, edition, pages
Umeå: Datavetenskap , 2008. , 34 p.
Series
Report / UMINF, ISSN 0348-0542 ; 08.01
Keyword [en]
Wireless Local Area Networks, Medium Access Control, Quality of Service, Resource Allocation, IEEE 802.11, IEEE 802.11e
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:umu:diva-1506ISBN: 978-91-7264-487-8 (print)OAI: oai:DiVA.org:umu-1506DiVA: diva2:141257
Public defence
2008-02-14, MA121, MIT huset, SE-901 87, Umeå, 13:00
Opponent
Supervisors
Available from: 2008-01-24 Created: 2008-01-24Bibliographically approved
List of papers
1. Distributed Utility based Resource Allocation in IEEE 802.11 Networks
Open this publication in new window or tab >>Distributed Utility based Resource Allocation in IEEE 802.11 Networks
2005 (English)In: Technical Report UMINF, ISSN 0348-0542, no 05.19Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Umeå: Umeå universitet, Institutionen för datavetenskap, 2005
Identifiers
urn:nbn:se:umu:diva-2905 (URN)
Available from: 2008-01-24 Created: 2008-01-24Bibliographically approved
2. A collision detection method for multicast transmissions in CSMA/CA networks
Open this publication in new window or tab >>A collision detection method for multicast transmissions in CSMA/CA networks
2007 (English)In: Wireless Communications & Mobile Computing, ISSN 1530-8669, Vol. 7, no 6, 795-808 p.Article in journal (Refereed) Published
Abstract [en]

Compared to unicast traffic, multicast is not protected by any ARQ mechanism in 802.11 networks: collisions with other multicast and unicast transmissions are not detected and senders will not adapt to the contention situation by backing off. This results in an unreliable service for multicast transmissions. We propose early multicast collision detection (EMCD), an algorithm with the purpose of increasing the reliability of multicast transmissions in the MAC layer of an IEEE 802.11 network. A multicast sender using it will introduce an early pause in a transmission, perform a clear channel assessment (CCA), and if a collision is detected abort the transmission after a fixed time and schedule a retransmission. This allows for detecting collisions with both multicast and unicast transmissions but also adapting to the contention situation. A probabilistic analysis is provided showing that EMCD is more efficient than ordinary multicast and can be made even more efficient by tuning parameters.

Keyword
quality of service, CSMA/CA, medium access control, 802.11, collision detection, reliable multicast, performance evaluation
Identifiers
urn:nbn:se:umu:diva-2906 (URN)10.1002/wcm.421 (DOI)
Available from: 2008-01-24 Created: 2008-01-24 Last updated: 2010-02-01Bibliographically approved
3. Prioritized repeated eliminations multiple access: A novel protocol for wireless networks
Open this publication in new window or tab >>Prioritized repeated eliminations multiple access: A novel protocol for wireless networks
2008 (English)In: The 27th Conference on Computer Communications (IEEE INFOCOM 2008), 2008, 1561-1569 p.Chapter in book (Other academic)
Abstract [en]

A new and simple MAC protocol is proposed. Each node transmits a burst with length sampled from a geometric distribution with parameter q followed by a carrier sense slot. A node repeats the previous operations until it senses a busy slot. A node will access the channel and transmit its payload when it has sensed h idle slots. The parameter q can be adjusted for each node to achieve desired levels of relative priority with little impact on channel utilization and without a need for explicit knowledge about other traffic. Comparison to existing tree-splitting, carrier sensing and bursting protocols through analysis and simulations shows that our algorithm scales very well to the number of nodes. It has very high success probability, channel utilization and fairness. Extensions are provided for hidden terminal scenarios and are shown in simulations to provide adequate performance.

Series
INFOCOM 2008. The 27th Conference on Computer Communications. IEEE, ISSN 0743-166X
Identifiers
urn:nbn:se:umu:diva-2907 (URN)10.1109/INFOCOM.2008.216 (DOI)
Available from: 2008-01-24 Created: 2008-01-24Bibliographically approved
4. Untruncated eliminations in the EY-NPMA MAC protocol: performance and optimality
Open this publication in new window or tab >>Untruncated eliminations in the EY-NPMA MAC protocol: performance and optimality
2007 (English)In: IEEE Communications Letters, ISSN 1089-7798, Vol. 11, no 2, 213-215 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-2908 (URN)
Available from: 2008-01-24 Created: 2008-01-24Bibliographically approved
5. Silent Elimination Multiple Access: An Efficient Channel Bursting Protocol
Open this publication in new window or tab >>Silent Elimination Multiple Access: An Efficient Channel Bursting Protocol
2007 (English)Manuscript (preprint) (Other academic)
National Category
Probability Theory and Statistics Computer Science
Identifiers
urn:nbn:se:umu:diva-2909 (URN)
Note

Submitted to Wireless networks (ISSN 1022-0038).

Ännu ej publicerad 20140319 /ME.

Available from: 2010-01-28 Created: 2009-03-12 Last updated: 2014-03-19Bibliographically approved
6. A Novel MAC Scheme for Solving the QoS Parameter Adjustment Problem in IEEE 802.11e EDCA
Open this publication in new window or tab >>A Novel MAC Scheme for Solving the QoS Parameter Adjustment Problem in IEEE 802.11e EDCA
Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:umu:diva-2910 (URN)
Available from: 2008-01-24 Created: 2008-01-24Bibliographically approved
7. Generic stationary backoff distributions for distributed multiple access control
Open this publication in new window or tab >>Generic stationary backoff distributions for distributed multiple access control
2014 (English)In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 56, no 3, 383-398 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, we study the characteristics of two different backoff schemes: one that maximizes the channel utilization and one that maximizes the probability of a successful transmission. Our results indicate that while the latter provides slightly lower channel utilization, its shape is much less sensitive to the number of contending nodes. That is, the channel utilization is kept almost constant for a very wide range of node densities if the backoff distribution has increasing shape. This motivates us to propose a simple heuristic backoff scheme called the Truncated Geometric Backoff Distribution (TGBD). We provide simple analytical expressions for the probability of a successful transmission and the channel utilization. We also show that the TGBD can easily be extended to support service differentiation by adjusting the window lengths, and we provide a simple approximation that gives the relative share of the capacity for a node in a priority class compared to nodes in other classes. This extended backoff scheme easily outperforms the much more complex Quality of Service (QoS) standard, IEEE802.11e EDCA. Finally, a two-stage backoff model, based on the TGBD, is proposed that further increases the probability of a successful transmission. Results indicate that the channel utilization is almost independent of the number of contending nodes.

Place, publisher, year, edition, pages
Dordrecht: Springer, 2014
Keyword
Stationary backoff distribution, Performance modeling, QoS, IEEE 802.11, IEEE 802.11e
National Category
Telecommunications
Identifiers
urn:nbn:se:umu:diva-2911 (URN)10.1007/s11235-013-9851-6 (DOI)000338231800007 ()
External cooperation:
Available from: 2008-01-24 Created: 2008-01-24 Last updated: 2016-08-26Bibliographically approved

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Citation style
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