Gbit Radios for the Mobile Anyhaul
Attila Hilt
Nokia Cloud and Network Services, Hungary
Budapest University of Technology and Economics, Faculty of Electronic Engineering and Informatics, Department of Broadband Infocommunications and Electromagnetic Theory, Hungary
ABSTRACT
Traditionally, the microwave and millimeter-wave
(μ/mmW) links have been limited by thermal noise. Long microwave
hops had to connect distant sites of several kilometers. The antennas
were mounted on high altitude towers. Unwanted interference was
eliminated with proper link design and frequency re-use plans. The
link design focused on Free Space Loss, rain and atmospheric
attenuation. Fading events (e.g., attenuation due to rain or multipath)
can significantly reduce the received signal level and degrade
the link performance. In worst case, the microwave connection is cut
resulting in outage. In the last two decades we observed a rapid
breakthrough in direct fiber-optical access. The very long microwave
backbone links have been systematically replaced by fiber-optics
wherever it was possible by terrain conditions. Consequently, the
majority of μ/mmW links became shorter and shorter. In urban
environments, the wireless hops are typically shorter than five-six
kilometers. On the other hand, there is a huge demand for a flexible
LTE, 5G and 6G front- and backhaul (commonly called anyhaul). In
mobile systems the μ/mmW anyhaul became extremely dense. 5G
and 6G mandate challenging user bit rate and latency requirements.
To avoid radio interference and support high link throughputs,
higher and higher carrier frequencies are introduced. State-of-theart
radios offer excellent possibilities in the millimetric (E, V and W)
bands. In the paper the long road to nowadays Gigabit radios is
presented. Starting from the very early microwave experiments, the
evolution of mobile networks and anyhaul is shown. Finally, some
design examples are presented for the recent use of the E-band.
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