Downlink Interference Control of LAA-LTE for Coexistence With Asymmetric Hidden Wi-Fi APs

Abstract

To confront the increasing mobile traffic demand and the scarcity of the licensed band, 3GPP has standardized a new type of LTE, called License Assisted Access (LAA) LTE (LAA-LTE), which aggregates licensed bands with unlicensed bands. Since the conventional Wi-Fi devices employ -62 dBm clear channel assessment threshold to LAA-LTE's signals, the appearance of LAA-LTE in the unlicensed band leads to a new phenomenon, asymmetric hidden terminal problem, which severely degrades the throughput and delay performance of LAA-LTE as well as Wi-Fi. We propose a downlink interference control scheme for an LAA-LTE eNB to prevent the asymmetric hidden Wi-Fi APs nearby from recklessly transmitting and thereby interfering the eNB's transmission. Specifically, we analyze the distortion of Wi-Fi's signals received at LAA-LTE and LAA-LTE's signals received at Wi-Fi due to the difference of physical-layer parameters between LAA-LTE and Wi-Fi. Based on this analysis, we develop an AP suppression and power control technique to control incoming and outgoing interference of the LAA-LTE eNB. Extensive simulations confirm that the proposed scheme improves the throughput and delay performance of LAA-LTE while maintaining or even improving the performance of Wi-Fi.