TRAI Ignores Broadcasters' Plea To Retain Frequency Gaurd Band In 5G

The Telecom Regulatory Authority of India (TRAI) has ignored the TV broadcasting industry's plea for keeping a 100 MHz guard band between the 3300-3670 MHz range. The TRAI has suggested reducing the guard band from 100 MHZ to 30 MHZ in this range.

A guard band is an unused frequency range that separates two ranges of wider frequencies ensuring that simultaneously used communication channels do not experience interference.

The broadcasting industry has been voicing its concern over the disruption of satellite services due to the reduction of this guard band. 

In response to the concerns raised, TRAI has suggested that there is a need to make use of high-quality bandpass filters operating in the 3700-4200 MHz range as the IMT emissions in the 3300-3670 MHz may saturate the Low Noise Block (LNB) of the FSS earth station which traditionally operates in the 3400-4200 MHz.

It also suggested that the Department of Telecom (DoT) should ask the Ministry of Information and Broadcasting (MIB) to take appropriate action and sensitize the multi-system operators (MSOs), DTH operators, and other users to ensure the use of high-quality bandpass filters operating in 3700-4200 MHz range to avoid interference from IMT stations.

"In order to avoid unwanted out-of-band emissions of the IMT stations falling within the FSS operating band 3700-4200 MHz, DoT should prescribe having a sharp Spectrum Mask for IMT transmitters with an out-of-band PFD limit," the TRAI said in its recommendations.

Stakeholders in the broadcasting and satellite industry have argued that the allocation of frequencies in the 3300-3670 band to 5G services beyond the current NFAP-18 upper limit of 3600 MHz will lead to serious disruption of Satellite services for media and broadcast in the 3700-4000 MHz band. Over 600 licensed satellite channels over India operate in this band.

The stakeholders also argued that filters of 3700-4200 MHz, even if used, cannot filter out these out-of-band emissions as these fall in the 3700-4200 MHz band.

They also contended that the Low Noise Blocks (LNBs) used in Cable Headends, which are typically designed for 3400-3900 MHz, would get overdriven (saturated) due to high terrestrial transmissions. This overdrive could have been prevented by the use of filters of 3700-4200 MHz but with Out of Band Emissions (OOBE) falling in the passband of filters, the interference will lead to a complete loss of signals.

Considering the interference concerns raised by the stakeholders, TRAI referred the matter to DoT. After conducting co-existence studies, the DoT concluded that the introduction of a cavity filter on the Television Receive-Only (TVRO) systems can make these systems co-exist with IMT/5G.

Even as it ignored the requests of the private broadcasters, the TRAI has taken care of the concerns of the public broadcaster with respect to the 526-582 MHz. The DoT had identified the 526-698 MHz band for IMT/5G services.

However, the frequency band 526-582 MHz is being used by Prasar Bharati (DD) for providing Terrestrial TV Broadcasting, many Analogue, Digital Ready, and Digital Terrestrial TV Transmitters are operating in this band.

"Considering the facts that presently (i) band plan(s) for the frequency range 526-612 MHz is yet to be defined by 3GPP/ITU, (ii) development of an ecosystem for IMT in 526-612 MHz frequency range will take some time and (iii) MIB is using 526-582 MHz band extensively across the country for TV transmitters; the 526-612 MHz frequency range should not be put to auction in the forthcoming auction," the TRAI stated.