ISLAMABAD: The government of Pakistan has identified 3300MHz to 3600MHz spectrum for 5G and there are likely no chances of interference with radio altimeters —essential component of aeronautical safety-of-life system.
This was confirmed by top officials of Pakistan Telecommunication Authority (PTA), while talking to Business Recorder.
Radio altimeters are an essential component of aeronautical safety-of-life systems. Some recent issues raised after launch of 5G in C Band (ITU Region 2: US) created an impression that Wireless Broadband (WBB) services in nearby frequency ranges have the potential to cause interference to radio altimeter receivers operating in the 4200–4400 MHz band via three different technical mechanisms (overload, de-sensitization and false altitude reports).
Radio altimeter measures altitude above the terrain presently beneath an aircraft or spacecraft by timing i.e. how long it takes a beam of radio waves to travel to ground, reflect, and return to the craft. This type of altimeter provides the distance between the antenna and the ground directly below it, in contrast to a barometric altimeter which provides the distance above a defined vertical datum, usually mean sea level, the official added.
Radar altimeters are frequently used by commercial aircraft for approach and landing, especially in low-visibility conditions and automatic landings. Sources said the 4200-4400 MHz band is a shared band internationally reserved for radio altimeters installed on aircraft.
In Pakistan, the FAB has also allocated same band for “Aeronautical Radio navigation”.
Radio altimeters operate in the 4200 to 4400 MHz band, and the US has set aside a portion of the spectrum right up to the lower band of that for 5G. The US auctioned 3.7-3.98 GHz 5G bandwidth to mobile phone companies in early 2021.
The FAA warned that the new 5G technology could interfere with instruments, such as altimeters. As short-term solution, mobile operators agreed to temporarily defer turning on some wireless towers near key airports to avert a significant disruption to US flights.
As longer-term solution, the FAA needs to clear and allow most of the US commercial airplane fleet to perform low-visibility landings at many airports where 5G C-band will be deployed. This means certifying altimeters to operate near 5G base stations.
The PTA officials said in Pakistan currently 3700-4200 MHz is being used for satellite projects. As per 5G Policy Guidelines issued by GoP 3300 MHz to 3600 MHz spectrum is identified for 5G and there are likely no chances of interference with radio altimeters.
Copyright Business Recorder, 2022
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