An Adaptive Contention Window Scheme for 802.11ah WLANs

In order to cope with the rapid development of the Internet of things, IEEE working group has proposed a new wireless network technology, 802.11ah. IEEE 802.11ah operates at sub 1GHz band, and can provide long transmission range, wide coverage, while supporting more than 6,000 of station to be connected. In order to alleviate the high collision probability, 802.11ah MAC protocol involves in the RAW (restricted access window) mechanism combined with grouping mechanism. However, in 802.11ah WLAN (wireless local area network), most of the stations operate at sleep mode, and it is expected that at the start of a BI, the network suffers much higher collision probability than at the latter period of the BI. In order to improve these drawbacks, we propose an adaptive contention window scheme based on which an optimum contention window size is adapted at the start of the BI, and then gradually halved when the transmission completes successfully. Through conducting simulations, we prove that our proposed protocol can enhance the performance of 802.11ah WLAN.

[1]  P. Venkata Krishna,et al.  Virtual Backoff Algorithm: An Enhancement to 802.11 Medium-Access Control to Improve the Performance of Wireless Networks , 2010, IEEE Transactions on Vehicular Technology.

[2]  Seung Hyong Rhee,et al.  Performance Improvement of Sub 1 GHz WLANs for Future IoT Environments , 2017, Wirel. Pers. Commun..

[3]  Evgeny M. Khorov,et al.  A survey on IEEE 802.11ah: An enabling networking technology for smart cities , 2015, Comput. Commun..

[4]  Athanasios V. Vasilakos,et al.  Semi-Random Backoff: Towards Resource Reservation for Channel Access in Wireless LANs , 2013, IEEE/ACM Trans. Netw..

[5]  Ali Hazmi,et al.  Feasibility study of IΕΕΕ 802.11ah radio technology for IoT and M2M use cases , 2012, 2012 IEEE Globecom Workshops.

[6]  Seung Hyong Rhee,et al.  Design of a collision-free backoff method to improve the IEEE 802.11 DCF , 2016, 2016 Eighth International Conference on Ubiquitous and Future Networks (ICUFN).

[7]  Saewoong Bahk,et al.  Group-based contention in IEEE 802.11ah networks , 2014, 2014 International Conference on Information and Communication Technology Convergence (ICTC).

[8]  Ignas G. Niemegeers,et al.  IEEE 802.11ah: Advantages in standards and further challenges for sub 1 GHz Wi-Fi , 2012, 2012 IEEE International Conference on Communications (ICC).

[9]  Boris Bellalta,et al.  CAS-based Channel Access Protocol for IEEE 802.11ah WLANs , 2014 .

[10]  Sunghyun Choi,et al.  EBA: an enhancement of the IEEE 802.11 DCF via distributed reservation , 2005, IEEE Transactions on Mobile Computing.

[11]  A. Girotra,et al.  Performance Analysis of the IEEE 802 . 11 Distributed Coordination Function , 2005 .

[12]  Hongjun Chen,et al.  Cooperative Transmission Mechanisms in Next Generation WiFi: IEEE 802.11ac , 2013, Int. J. Distributed Sens. Networks.