The government has designated 3300 MHz to 3600 MHz spectrum for 5G, and there appears to be no risk of interference with radio altimeters, which are an essential component of the aeronautical safety-of-life system.
While speaking with a blog website, top officials from Pakistan Telecommunication Authority (PTA) confirmed this.
Radio altimeters are a critical component of aeronautical life-saving systems. Some recent issues raised following the launch of 5G in the C Band (ITU Region 2: US) gave the impression that Wireless Broadband (WBB) services in nearby frequency ranges could potentially cause interference in radio altimeter receivers operating in the 4200 to 4400 MHz band via three different technical mechanisms (overload, de-sensitization, and false altitude reports).
By timing, a radio altimeter determines the altitude above the terrain that is currently beneath an aircraft or spacecraft (essentially how long it takes a beam of radio waves to travel to the ground, reflect, and return to the craft).
A PTA official added that this type of altimeter provides the distance between the antenna and the ground directly below it, as opposed to a barometric altimeter, which provides the distance above a defined vertical datum, which is usually mean sea level.
Commercial aircraft frequently use radar altimeters for approach and landing, particularly in low-visibility conditions and for automatic landings.
According to sources, the 4200-4400 MHz band is a shared band that is globally reserved for radio altimeters installed on aircraft.
Pakistan’s Frequency Allocation Board (FAB) has also designated the same band for ‘Aeronautical Radio Navigation.’
Radio altimeters operate in the 4200 to 4400 MHz band, and the United States has reserved a portion of the spectrum up to the lower band for 5G. In early 2021, it also auctioned off 3.7-3.98 GHz 5G bandwidth to mobile phone companies.
The Federal Aviation Administration (FAA) of the United States had warned that new 5G technology could interfere with instruments such as altimeters. As a short-term solution, mobile operators agreed to postpone the activation of some wireless towers near major airports in order to avoid significant disruption to American flights.
As a long-term solution, the FAA should clear and allow most American commercial plane fleets to perform low-visibility landings at many airports where 5G C-band will be deployed. This entails certifying altimeters to operate in close proximity to 5G base stations.
According to PTA officials, Pakistan is using 3700-4200 MHz for satellite projects. According to the Government of Pakistan’s 5G Policy Guidelines, the 3300 MHz to 3600 MHz spectrum is designated for 5G, and interference with radio altimeters is unlikely.
To read our blog on “Govt. is consulting industry players on 5G adoption nationwide,” click here.
