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Long Term Rain Attenuation Measurements for Millimeter Wave Short-range Fixed
Links for 5G applications
Othman Zahid, Jie Huang, and Sana Salous
Department of Engineering, Durham University, Durham, DH1 3LE U.K.
Email: {othman.zahid, jie.huang, sana.salous}@durham.ac.uk
Millimeter wave (mmWave) communication is a key technology for the fifth generation (5G) wireless
communications and can be used for fronthaul, backhaul, and fixed link building to building transmission
to provide high data transmission rate in indoor and outdoor environments. The electromagnetic wave
above 10 GHz suffers more from rain attenuation, which causes the performance reduction and even
outage of the communication system at mmWave bands for 5G fixed links. Therefore, rain attenuation
effect on mmWave bands becomes an important issue and should not be neglected. The rain
attenuation depends on the rain rate, rain drop size distribution (DSD), and complex water refractive
index.
Several works have been done to study the effect of precipitation on mmWave fixed links, and
most of terrestrial link measurements are dedicated for long range and line of sight (LOS) links. The
study needs a long term measurement over several years for accurate and useful results which should
be qualified for a reliable radio link during precipitation events along the year.
At Durham University, to study the rain attenuation on mmWave bands for 5G fixed link, a custom-
designed continuous wave (CW) channel sounder is utilized to record channel data at K band (25.84
GHz) and E band (77.52 GHz) for direct and side fixed links with dual polarizations and a high
performance PWS100 disdrometer is applied to collect weather data, including rain rate and rain DSD
as shown in Fig.1 (a).
The setup uses a transmitter (Tx) box shown in Fig.1 (b), a receiver (Rx) box for direct link (c), and
receiver box for side link (d). The distance between the Tx and Rx is about 35 m for the direct link. The
measurement setup conducts rain attenuation measurements and modeling for short-range building to
building transmission scenario.
Furthermore, the channel sounder has been updated based on the previous
system [1], [2] in order to reduce the system attenuation loss, simplify the system, make it more stable
than before, and also study the rain attenuation for both direct and side links simultaneously. Preliminary
measurements after the update illustrate the impact of rain on the received signal strength shown in
Fig.2. However, the side link has a larger variation due to multipath fading. The rain attenuations for
direct and side fixed links are thoroughly compared for the two bands. The ITU-R P.838-3 model and
DSD model are applied to rain attenuation modelling.
References
[1] S. Salous, Y. Cao, and X. Raimundo, “Impact of precipitation on millimetre wave fixed links,” in Proc.
EuCAP’19, Krakow, Poland, Apr. 2019, pp. 1–4.
[2] J. Huang, Y. Cao, X. Raimundo, A. Cheema, and S. Salous, “Rain statistics investigation and rain
attenuation modeling for millimeter wave short-range fixed links,” IEEE Access, vol. 7, pp. 156110-
156120, 2019.
Figure 1. Fixed link experimental setup for rain
attenuation study.
(a) Weather
station
(b) Tx box
(c) Rx
direct link
(d) Rx
side link
Figure 2. The received signal against the rain
intensity on November 7, 2019.