International Journal of Electrical and Computer Engineering (IJECE) Vol. 10, No. 3, June 2020, pp. 2589~2599 ISSN: 2088-8708, DOI: 10.11591/ijece.v10i3.pp2598-2599  2589 Journal homepage: http://ijece.iaescore.com/index.php/IJECE Security-aware fair transmission scheme for 802.11 based cognitive IoT Hayoung Oh DASAN University College, Ajou University, South Korea Article Info ABSTRACT Article history: Received Mar 29, 2019 Revised Nov 24, 2019 Accepted Dec 9, 2019 Cognitive IoT is exponentially increased because of various real time and robust applications with sensor networks and big data analysis. Each IoT protocol of network layer can be RPL, COAP and so on based on IETF standards. But still collision problems and security-aware fair transmission on top of scalable IoT devices were not solved enough. In the open wireless LAN system based cognitive IoTs, IoT node that is continuously being stripped of its transmission opportunity will continue to accumulate packets to be sent in the butter and spoofing attacks will not allow the data transfer opportunities to be fair. Therefore, in this paper, we propose a method to reduce the average wait time of all packets in the system by dynamically controlling the contention window (CW) in a wireless LAN based cognitive IoT environment where there are nodes that do not have fair transmission opportunities due to spoofing attacks. Through the performance evaluation, we have proved that the proposed technique improves up to 80% in terms of various performance evaluation than the basic WLAN 802.11 based IoT. Keywords: Cognitive IoT DCF (distributed coordination function) IEEE 802.11 Queue management Security-aware fair transmission Copyright © 2020 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Hayoung Oh, DASAN University College, Ajou University, Suwon 16499, South Korea. Email: hyoh79@gmail.com 1. INTRODUCTION With the development of cognitive IoTs (CIoTs) [1] with sensors and big data analysis [2], real time and robust applications are exponentially attended all over the world [3-8]. Even though those techniques were famous with the reflection of IETF standards such as Orchestra [9], RPL (IPv6 Routing Protocol for Low power and Lossy Networks) [10], TSCH (Time Slotted Channel Hopping MAC) [11] and COAP enough years ago, the exact and strict solutions for secure wireless transmission of cognitive IoTs were not provided in the research and other areas in practice. In the 802.11 protocol, the concept of a fundamental mechanism for accessing media is DCF. The DCF is a standard CSMA/CA access mechanism, back-off time is used to avoid collisions by checking whether the wireless channel is empty before the transmission. In DCF, the more nodes competing, the more likely it is that collisions will occur and the transmission will not be fair. Many researches has been done to solve this problem. But those were not considered in CIoTs environment enough. For example, when a collision occurs, the backoff of the corresponding node exponentially increases, the backoff of other nodes increases linearly [12, 13], and when the transmission is completed, a new backoff algorithm that linearly reduces the backoff of all nodes. A method of allocating different CW values according to the number of collisions occurring in the nodes is proposed [14]. Figure 1 shows Media Access Control (MAC) Layer 2 attacks in 802.11 based CIoT. An attacker of MAC can transmit packets using a spoofed source MAC address of an access point at any time. The recipient of these spoofed frames has no way of identifying if they are legitimate or illegitimate requests and will process them. The ability to transmit spoofed management frames causes MAC layer DoS attacks on an open