32-GHz Outdoor-to-Indoor Channel Measurement of Propagation Losses and Delay Spread

This paper presents millimeter-wave (mmWave) propagation losses and delay spread characteristics, based on outdoor-to-indoor (O2I) channel measurements. The measurements were conducted in an office building at 32 GHz. Although the results of the propagation loss measurement are similar to the ITU-R and the 3GPP model, the delay spread result is quite different from the 3GPP model. It should be noted that delay spread models for O2I scenarios in the 3GPP are identical to both above 6 GHz and below 6 GHz. We also considered the propagation characteristics in terms of indoor propagation environments in that typical O2I propagation is affected not only by the building penetration but also by the indoor propagation. We believe that these mmWave O2I characteristics will be useful for 5G system design and evaluations.