Maximum-Likelihood-Based Location, Orientation, Transmitted Power, and Antenna Beamwidth Estimator Utilizing the Angle-of-Arrival and Received Power for Spectrum Sharing at Millimeter Wave Bands

The fifth-generation (5G) system utilizing millimeter wave is available in Japan, but more bandwidth is demanded by the mobile phone operators to accommodate the demand for high data rate. Allocation of the vacant spectrum is impossible due to the past spectrum allocation to other radio systems. For example, 24.25-27.5 GHz has been allocated for the fixed wireless access (FWA) and license exempt small power data communication system in Japan. Although Japanese government is considering to license a part of the band for 5G under the spectrum sharing scheme, the coexistence design is quite challenging due to unavailable operation data of such systems in a form of database for the coexistence study. For this purpose, this paper introduces a maximum-likelihood estimator (MLE), which utilizes the angle-of-arrival (AoA) and received power of the line-of-sight (LOS)/diffraction paths as well as the map database to simultaneously estimate these unknown parameters via the spectrum sensing. It was applied to the measurement data obtained from a sub-urban environment where a commercial fixed wireless access system with similar operational parameters is under operation. Its performance was evaluated for a different number of receiver (Rx) points. The results showed that the parameter estimation accuracy is proportional to the number of receiver points. The distance and orientation errors of 45 m and 5 deg were achieved at 90th percentile with 40 Rx points. Furthermore, the prediction performance of the effective isotropic radiated power (EIRP) was decent, albeit a slight underestimation of the beamwidth.