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Performance Enhancement Optimizing Contention Window in IEEE 802.11 Wireless Local Area Networks
- Alternative Title
- Performance Enhancement Optimizing Contention Window in IEEE 802.11 Wireless Local Area Networks
- Author(s)
- SYED, IKRAM
- Alternative Author(s)
- SYED IKRAM
- Advisor
- Byeong-hee Roh
- Department
- 일반대학원 컴퓨터공학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2017-08
- Language
- eng
- Keyword
- IEEE 802.11; Wireless LAN; MAC protocol; Adaptive Contention window; Internet of Things (IoT)
- Alternative Abstract
- IEEE 802.11 Wireless LANs are becoming the most popular and widely deployed networks, and a tremendous growth has been noticed in wireless connected devices, and this upward trend will continue for the coming years. By 2020, the number of wireless devices are expected to reach over 40 billion. However, the efficiency of the IEEE 802.11 MAC protocol is a challenging task when the network is deployed in dense environment. This thesis focuses on the enhancement of IEEE 802.11 MAC protocol in a dense and widely fluctuating network loads. Firstly, we observe that the high data rates of PHY layer do not necessarily translate into corresponding increase in MAC layer throughput due to the contention of the random backoff algorithm based MAC layer. To reduce the contention among contender stations, we propose an adaptive backoff algorithm for MAC layer that maximizes the system throughput, reduces the collision probability, and maintains a high fairness for the IEEE 802.11 DCF under dense network conditions. Secondly, we investigate the Quality of service (QoS) for MAC layer, which is one of the critical aspects for real-time applications in wireless LANs. To improve the QoS for the MAC layer in terms of delay and throughput. We propose an extensive analytical model for the adaptive backoff algorithm for the IEEE 802.11e EDCA networks and derived an explicit expression for the mean frame delay, collision probability, and network throughput. The main objective of this work is to find the optimal CW parameters for each AC in order to achieve maximum throughput and small mean frame delay under saturated network condition. Thirdly, we investigate the performance of Restricted Access Window within TIM group in dense network environment. The efficiency for the restricted access window mechanism in term of collision rate and throughput reduces when the number of contender stations increase within the TIM group. To improve the efficiency of the restricted access window mechanism for the TIM group in a dense environment, we adopt an adaptive backoff mechanism for the contention among TIM group’s stations. The simulation results confirmed that the adaptive backoff mechanism achieves better network throughput and low collision rate compared with the IEEE 802.11ah RAW mechanism.
- Fulltext
- Appears in Collections:
- Graduate School of Ajou University > Department of Computer Engineering > 4. Theses(Ph.D)
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