LTERadar: Towards LTE-Aware Wi-Fi Access Points

Major cellular hardware vendors (e.g. Qualcomm, Ericsson), mobile service providers (e.g. Verizon, T-Mobile) and standardization bodies (LTE-U forum, 3GPP) are seeking to extend LTE networks into unlicensed bands to boost LTE speeds and coverage. However, the advent of LTE unlicensed technologies has raised serious concerns on Wi-Fi networks that are operating in the same bands. In this work, we evaluate LTE/Wi-Fi coexistence, by conducting experiments with commodity LTE unlicensed and state-of-the-art 802.11ac Wi-Fi testbeds. Our experimental results show that LTE-induced interference not only can decrease Wi-Fi throughput by an order of magnitude, but also significantly impact the operation of 802.11ac high-throughput features (MU-MIMO, channel bonding, rate adaptation). To this end, we design LTERadar, a lightweight interference detector that runs on Wi-Fi devices and accurately detects LTE interference. LTERadar is independent of the technology of LTE interferer (LTE-U or LAA, the dominant LTE unlicensed protocols). Our implementation and evaluation with off-the-shelf Wi-Fi APs show LTERadar's interference detection accuracy to be more than 90% in realistic settings. We corroborate the 90% accuracy of LTERadar out in the wild, under dense enterprise Wi-Fi environments.