ISU Electrical and Computer Engineering Archives

MAC-layer approaches for security and performance enhancement in IEEE 802.11

Wang, Hao-Li (2004) MAC-layer approaches for security and performance enhancement in IEEE 802.11. PhD thesis, Iowa State University.

Full text available as:

PDF - Requires Adobe Acrobat Reader or other PDF viewer.


Over the past few years, wireless networks are becoming increasingly popular. The dominant question facing the wireless network today is: how can the network meet the needs of various users and applications? Two basic and primary needs for users are efficiency and security. To deal with these two concerns, this dissertation investigates the two areas and proposes four MAC-level approaches for security and performance enhancement in IEEE 802.11 In the first part, we propose three MAC-level approaches to improve the throughput performance in wireless LANs, i.e., the Freeze Counter scheme (FC), the Dynamically Adaptive Retransmission (DAR), and the Quick Acknowledgement (QA) scheme. The Freeze Counter scheme is an adaptive error recovery mechanism in 802.11, which can perform different actions according to the reasons for frame losses. With the differentiation functionality, the non-collision error frames could be rapidly retransmitted without the binary exponential backoff procedure. Next, Dynamically Adaptive Retransmission scheme is an enhanced feedback scheme in 802.11, in which the CTS frames carry additional information concerning the previous data delivery without violating the 802.11 MAC layer semantics. Thirdly, we propose a Quick Acknowledgement (QA) scheme as a replacement for positive acknowledgement in IEEE 802.11. QA is an adaptation of an ATM-based protocol, the Service Specific Connection Oriented Protocol (SSCOP), for use as a link layer protocol in wireless LANs. By using similar concepts as selective ACK and negative ACK, the proposed protocol solves the inefficiency problem of positive ACK in 802.11, and therefore it performs better than 802.11 MAC. The second part of the dissertation is to enhance the security in WLANs. In the second part, we propose a lightweight statistical authentication protocol for wireless networks. With more and more applications on wireless networks, new concerns are raised when it comes to security issues. Authentication service particularly becomes one of the basic but necessary security measures for wireless applications. However, traditional authentication protocols for wired networks do not work well in a wireless environment due to unique characteristics, such as error-prone wireless transmission medium, node mobility, and power conservation constraints of wireless devices. To meet this target, we propose a lightweight statistical authentication protocol for wireless networks, namely \emph{Shepherd}. To solve the inherent out-of-sync problem with Shepherd protocol, we develop three synchronization schemes with their statistical methods. In Shepherd, the legitimacy of a mobile node is determined by continuously checking a series of random authentication bits where each bit in this stream is piggybacked by a packet. Such an authentication bit stream is generated by both mobile node and access point using the same random number generator under the same shared seed as a key. The complete evaluation and analysis of all proposed approaches have been discussed. We also show that the proposed approaches are practical for implementation in 802.11 to improve the security and performance of wireless LANs.

EPrint Type:Thesis (PhD)
Subjects:Computer Engineering > INFORMATION SYSTEMS SECURITY & NETWORKING > Information Assurance
Computer Engineering > INFORMATION SYSTEMS SECURITY & NETWORKING > Computer Networking and Security
ID Code:49
Identification Number:Identification Number UNSPECIFIED
Deposited By:Mr. Hao-Li Wang
Deposited On:20 April 2004

Archive Staff Only: edit this record