An SDR-Based Performance Measurement of LTE and WLAN Coexistence

In this paper, we report on a software-defined radio (SDR) based test setup to emulate and evaluate the performance of two wireless coexistence scenarios. The first case we study consists of two long-term evolution (LTE) downlink channels from adjacent cells, and the second case is formed by an LTE downlink channel coexisting with a wireless local network (WLAN) channel. Different from available SDR measurement works, this test design provides new methods such as real-time adjustment of communication and inter-cell interference (ICI) channel gains, the measurement of SDR receiver internal noise power and noise figure, and the measurement of link signal-to-interference-and-noise ratio (SINR). We compare the measured LTE SINR-to-throughput mapping result with a theoretical upper bound which assumes 3GPP reference channel quality indicator (CQI) values and an ideal communication hardware. Our measurement results illustrate the SINR gap caused by the effects of imperfect SDR hardware and noise figure, and show interesting findings about LTE and WLAN performance under varying mutual interference conditions. Our SDR design and measurement methods can be extended to support the performance evaluation and optimization of more general multicell LTE and WLAN coexistence systems.