Towards LTE-U Interference Detection, Assessment and Mitigation in 802.11 Networks using Commodity Hardware

We propose WiPLUS – a system that enables WiFi to deal with the stealthy invasion of LTE-U into the frequency bands used by WiFi. Using solely MAC layer information extracted passively, during runtime, out of the hardware registers of the WiFi NIC at the WiFi access point, WiPlus is able to: i) detect interferring LTE-U signals, ii) compute their duty-cycles, and iii) derrive the effective medium airtime available for each WiFi link in a WiFi Basic Service Set (BSS). Moreover WiPLUS provides accurate timing information about the detected LTE-U ON and OFF phases enabling advanced interference mitigation strategies such as interference-aware scheduling of packet transmissions, rate adaptation and adapting channel bonding. WiPlus does not require any modifications to the WiFi client stations and works with commodity WiFi APs where it has a simple software installation process. We present the design, the implementation details and the evaluation of the WiPlus approach. Evaluation results reveal that it is able to accurately estimate the effective available medium airtime for each link in a WiFi BSS under a wide range of LTE-U signal strengths with a rootmean-square error of less then 3 % for the downlink and less 10 % for the uplink. Index Terms WiFi, IEEE 802.11, LTE-U, RF Device Detection, Interference, Capacity, Wireless Network Monitoring Copyright at Technische Universität Berlin. All Rights Reserved. TKN-17-0001 Page 2