Separate 5G band and aviation radar frequency: Bharti Airtel to Trai

Experts say that unlike the US, India already has a large separation between the two bands

Bharti Airtel has written to the Telecom Regulatory Authority of India (Trai), stating that in order for them to co-exist with the country’s aviation system, no radar should operate in the 3.3 GHz to 3.67 GHz band, and any existing operations should be moved 100 MHz or more from the operating range of 5G networks.

With the launch of 5G services sparking discussions on aviation safety worldwide, Airtel has pointed out to the Trai that it is “critical to identify any interference from a 5G system operating in the 3.5 GHz band with radar altimeters deployed in the Indian aviation systems.” The band is crucial for telcos, as it will be auctioned for offering 5G services, which are expected to roll out at the end of this year.

Airtel has also told the regulator that the exact amount of separation between the 3.5 GHz band and that of the radar system can be finalised depending on the “permitted noise floor” in the aviation radar system and “spurious out of band” emission from 5G towers and mobile phones operating within the airport and the aircraft.

A bitter standoff is currently playing out between airlines and mobile operators in the US, which may force many carriers such as the Emirates, Air India (it cancelled eight flights to the US earlier this week) and Japanese Airlines to suspend flying into the country’s airports where 5G services are being launched. 

Airlines say that 5G airwaves affect the operation of aircraft equipment used for landing in rough weather and preventing crashes. The radio frequencies of the altimeters in the plane are used to measure the distance of the plane to the ground and help in landing safely. However, the proximity of 5G airwaves in the C band to the frequency used by altimeters could lead to interference and, hence, serious consequences.  

However, US telecom operators insist that there is no such interference in cockpit devices.   

As the aviation and telecom sectors thrash out a solution to this contentious issue, a temporary truce has been arrived at. Mobile operators AT&T and Verizon, which began to deploy their 5G services in the US from January 19, have decided that they won’t extend the network to airports (2 km range) for now. 

Experts say that the issue may not be so contentious in India, though tests need to be done. The aviation radar system in India uses the 4.2-4.4 GHz band (like other parts of the world) and only up to 3.7 GHz will be used for 5G services (compared to 3.98 GHz in the US). Hence, there is already a large gap between the two to obviate any interference of 5G airwaves on aircraft equipment. 

Moreover, the US has many old planes with legacy altimeters. “That is why the 5G problem is arising only in the US, and may not arise in countries with younger fleet,” says a senior executive of a telecom gear company.