Indoor Coverage Enhancement for mmWave Systems with Passive Reflectors: Measurements and Ray Tracing Simulations

The future 5G networks are expected to use millimeter wave (mmWave) frequency bands, mainly due to the availability of large unused spectrum. However, due to high path loss at mmWave frequencies, coverage of mmWave signals can get severely reduced, especially for non-line-of-sight (NLOS) scenarios. In this work, we study the use of passive metallic reflectors of different shapes/sizes to improve mmWave signal coverage for indoor NLOS scenarios. Software defined radio based mmWave transceiver platforms operating at 28 GHz are used for indoor measurements. Subsequently, ray tracing (RT) simulations are carried out in a similar environment using Remcom Wireless InSite software. The cumulative distribution functions of the received signal strength for the RT simulations in the area of interest are observed to be reasonably close with those obtained from the measurements. Our measurements and RT simulations both show that there is significant (on the order of 20 dB) power gain obtained with square metallic reflectors, when compared to no reflector scenario for an indoor corridor. We also observe that overall mmWave signal coverage can be improved utilizing reflectors of different shapes and orientations.