WiFi leakage detection in LTE downlink for in-device interference avoidance

To allow users to access networks and services ubiquitously, more and more user equipments (UEs) are equipped with multiple radio transceivers. However, due to the proximity of transmit and receive frequencies of in-device wireless technologies, the transmitter (TX) of one in-device wireless technology can interfere with the reception of another wireless technology within the same device, and the spurious emissions of the aggressor TX may result in unacceptable interference at the victim receiver which is co-located in-device. Hence, it is crucial to detect the in-device interference and adapt the strategies to avoid harm. In this paper, we consider the scenario of LTE coexisting with WiFi. Different from traditional spectrum sensing in cognitive radio which detects signal in the background of Gaussian noise, the WiFi leakage detection problem in this paper aims to detect WiFi leakage in the background of LTE signal and Gaussian noise. This makes the problem challenging. By identifying unique features of the WiFi leakage, we investigate this problem thoroughly and propose two detection algorithms, including entropy ratio based and cyclostationary based algorithms. Simulation results under different scenarios are presented to illustrate the effectiveness and efficiency of the proposed detection techniques.