Abstract
In future 5G systems, the millimeter wave (mmWave) band will be used to support a large capacity for current mobile broadband. Therefore, the radio access technology (RAT) should be made available for 5G devices to help in distinct situations, for example device-to-device communications (D2D) and multi-hops. This paper presents ultra-wideband channel measurements for millimeter wave bands at 19, 28, and 38 GHz. We used an ultra-wideband channel sounder (1 GHz bandwidth) in an indoor to outdoor (I2O) environment for non-line-of-sight (NLOS) scenarios. In an NLOS environment, there is no direct path (line of sight), and all of the contributed paths are received from different physical objects by refection propagation phenomena. Hence, in this work, a directional horn antenna (high gain) was used at the transmitter, while an omnidirectional antenna was used at the receiver to collect the radio signals from all directions. The path loss and temporal dispersion were examined based on the acquired measurement data—the 5G propagation characteristics. Two different path loss models were used, namely close-in (CI) free space reference distance and alpha-beta-gamma (ABG) models. The time dispersion parameters were provided based on a mean excess delay, a root mean square (RMS) delay spread, and a maximum excess delay. The path loss exponent for this NLOS specific environment was found to be low for all of the proposed frequencies, and the RMS delay spread values were less than 30 ns for all of the measured frequencies, and the average RMS delay spread values were 19.2, 19.3, and 20.3 ns for 19, 28, and 38 GHz frequencies, respectively. Moreover, the mean excess delay values were found also at 26.1, 25.8, and 27.3 ns for 19, 28, and 38 GHz frequencies, respectively. The propagation signal through the NLOS channel at 19, 28, and 38 GHz was strong with a low delay; it is concluded that these bands are reliable for 5G systems in short-range applications.
Highlights
The spectrum with a range of 1–100 mm (3–300 GHz band) wavelengths can be classified as millimetre-Wave bands [1,2]
The path loss exponents (PLEs) with verity reference distances were high in the hard-NLOS scenario compared with the others [13,15,16]
We have described the large-scale path loss in a 5G network for a wideband channel, in a specific indoor to outdoor environment measurement campaign conducted at the Universiti Teknologi Malaysia (UTM)-KL campus
Summary
The spectrum with a range of 1–100 mm (3–300 GHz band) wavelengths can be classified as millimetre-Wave (mm-Wave) bands [1,2]. Shu Sun et al studied indoor propagation measurements at 2–73 GHz in LOS and NLOS for offices and shopping malls, and the measured path loss as a function of distances [13] They have carried through measured information and ray tracking of 28 to 73.5 GHz in the mmWave frequency bands, comparing trajectory models. While propagation studies for the coexistence of 5G in the mmWave bands have been aggressively performed for some time, the characterization of the 5G channel model still requires further investigation This is because most of the measurement campaigns are conducted using different settings, including measurement environments; morphologies; equipment like channel sounder, antennas, and clock synchronization; and even the post-processing method, which may influence the propagation characteristics.
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