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ieee-802-11-mac-protocols
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History based contention window control in IEEE 802.11 MAC protocol in error prone channel
, Article Journal of Computer Science ; Volume 6, Issue 2 , 2010 , Pages 205-209 ; 15493636 (ISSN) ; Movaghar, A ; Jabbehdari, S ; Sharif University of Technology
2010
Abstract
Problem statement: IEEE 802.11 Medium Access Control (MAC) protocol is one of the most implemented protocols in this network. The IEEE 802.11 controls the access to the share wireless channel within competing stations. The IEEE 802.11 DCF doubles the Contention Window (CW) size for decreasing the collision within contending stations and to improve the network performances but it is not good for error prone channel because the sudden CW rest to CWmin may cause several collisions. Approach: The research to date has tended to focus on the current number of active stations that needs complex computations. A novel backoff algorithm is presented that optimizes the CW size with take into account...
Enhancement of full-duplex efficiency in an asymmetric IEEE 802.11-based WLAN
, Article IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 4 September 2016 through 8 September 2016 ; 2016 ; 9781509032549 (ISBN) ; Ashtiani, F ; Mirmohseni, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In this paper, we propose a new packet prioritization scheme in order to exploit the full-duplex (FD) capability of the access point (AP) more efficiently, in an asymmetric IEEE 802.11-based WLAN, i.e., only the AP has the in-band FD communications capability. In this respect, we consider a modified version of IEEE 802.11 MAC protocol such that at any transmission opportunity in which AP has the role of the transmitter or the receiver, it does the best to select a partner packet to be simultaneously received or transmitted, respectively. The key feature of our proposed partner packet selection scheme is to reduce the idle time intervals that in an FD transmission opportunity, due to...
AMACA - A new multiple access collision avoidance scheme for wireless lans
, Article 2004 International Workshop on Wireless Ad-Hoc Networks, Oulu, 31 May 2004 through 3 June 2004 ; 2005 , Pages 238-242 ; 0780382757 (ISBN) ; Khalaj, B. H ; Sharif University of Technology
2005
Abstract
It's well known that "hidden- and exposed-terminal" are among the main problems in ad-hoc WLAN networks. In addition, there are scenarios where the desired destination is located in the range of other transmitters, so that the efforts on setting up communication with this terminal will fail due to collisions occurred between desired control packets and unwanted received data packets at destination. In such scenarios, conventional protocols can not address the problem efficiently, resulting in throughput and channel utilization degradation. In this paper, by using the same PHY of IEEE 802.11 and making slight changes in its MAC layer, a new MAC protocol is presented to address such problems....
Saturation throughput analysis of a cognitive IEEE 802.11-based WLAN overlaid on an IEEE 802.16e WiMAX
, Article IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 9 September 2012 through 12 September 2012 ; September , 2012 , Pages 1515-1520 ; 9781467325691 (ISBN) ; Moradian, M ; Ashtiani, F ; Sharif University of Technology
2012
Abstract
In this paper, we focus on a cognitive network scenario, comprised of a WLAN overlaid on a network with time-scheduled primary users. WiMAX is an example of such primary networks. For time-scheduled primary users simple On-Off traffic model with exponential durations is not valid anymore. In this scenario, the cognitive nodes (CNs) hear downlink map (DL-MAP) and thus, know the frequency and time locations of all allocated slots at each frame. Then, cognitive nodes contend with each other in order to transmit their fixed size packets based on IEEE 802.11 MAC protocol. Since the number of empty slots at each frame is variable each packet transmission in cognitive network prolongs a random...
The novel contention window control scheme for IEEE 802.11 mac protocol
, Article NSWCTC 2010 - The 2nd International Conference on Networks Security, Wireless Communications and Trusted Computing, 24 April 2010 through 25 April 2010, Wuhan ; Volume 2 , April , 2010 , Pages 134-137 ; 9780769540115 (ISBN) ; Movaghar, A ; Sharif University of Technology
2010
Abstract
The IEEE 802.11 medium access control (MAC) protocol defines a contention-based distribution channel access mechanism that shares the wireless medium for mobile stations. In this paper, we present a novel backoff mechanism, which divides contention window range to the different level based on the history of channel status. Instead of doubling and resetting the CW, we change the CW range by taking into account last three channel states. We test the new scheme against legacy IEEE 802.11 with NS-2 network simulator. The simulation results have shown 30.77% improvement in packet delivery ratio and 31.76% in delay and 30.81% in throughput compared to the IEEE 802.11 DCF