The ongoing dispute between Airtel and BSNL over the private telecom major’s complaint of network interference in Rajasthan likely stems from spectrum allocation to the two service providers and not equipment, sources have said.
Airtel has blamed Tejas Networks’ “faulty equipment” for the problem with its network, a charge denied by the Tata-owned company which helmed BSNL’s 4G rollout.
Sources close to Tejas Networks said the problem lies in the limited guard band between spectrum blocks allocated to Airtel and BSNL rather than from the equipment.
“Airtel is raising the complaint with the wrong party. The issue is not with the radio equipment. The cause is the band allocated to BSNL and the inadequate guard band between the two operators’ spectrum blocks,” one of the sources told Moneycontrol on condition of anonymity.
Antennas with built-in filters have already been installed across 1,000 BSNL sites and Airtel should coordinate with the state-owned operator to expand deployment to additional locations to mitigate interference, sources said.
The Wireless Planning and Coordination (WPC) wing of the DoT assigned the band without following 3GPP-recommended guard band norms. “This is not an equipment fault. It is a spectrum-planning issue,” the source said.
Tejas has said its radios are compliant with 3GPP standards and have been validated by independent third-party testers. “The interferenc arises because the guard band is ‘too narrow,’ leading to spillover despite standards-compliant hardware,” the source added.
The person also said Airtel has not approached BSNL, even though “technically the complaint should be made to BSNL, since it is BSNL’s spectrum property”.
A filter — though not part of the original tender specifications — could fix the issue and BSNL would ultimately need to procure it, sources said.
In a November 24 letter to Airtel, Arnob Roy, executive director and chief operating officer at Tejas, said all radios deployed in the B05 band in Rajasthan meet standards and are on par with equipment from other OEMs, including those used by Airtel, especially in terms of out-of-band emissions.
“There is no rationale whatsoever for Airtel to classify them as sub-standard, and we express our disappointment that such a baseless statement is being made from a company of Airtel's stature. We recommend that Airtel work with BSNL to have the antennas with the built-in filters installed at additional sites beyond the 1,000 sites where they have already been installed,” he wrote.
Moneycontrol has reviewed a copy of the letter which was marked to telecom minister Jyotiraditya Scindia, the DoT secretary, and the BSNL CMD.
Tejas Networks is a responsible company and “we have been working with diligence in our country's indigenisation efforts in building the telecom technology successfully. The radios supplied by Tejas Networks are fully compliant with 3GPP standards”, he said.
Airtel counter
An Airtel spokesperson rejected Tejas’s assertions, calling them baseless.
“Towers have historically accommodated two or more sites of different operators without interference, so the problem isn’t due to closeness of sites. The current problem is more a function of sub-standard equipment which doesn’t conform to Indian spectrum allocation requirements,” the spokesperson said.
Airtel said radio gear from all global vendors in the 850 MHz band complies with Indian frequency allocation rules, ensuring signals turn off within required limits and do not interfere with the 900 MHz uplink.
But Tejas-made radios for the 850 MHz band used by BSNL “radiate signals beyond those limits”, disrupting its 900 MHz uplink, Airtel said, adding that Tejas must use a filter to restrict emissions.
Queries sent to the DoT and Tejas Networks didn’t elicit any response.
Tejas’s technical rebuttal
According to Tejas’s letter, the radios were designed per BSNL tender specifications. All radio models deployed in BSNL’s network meet emission requirements “with very good margin”, backed by reports submitted to WPC and Wireless Monitoring Organisation (WMO).
During joint measurements conducted with Airtel and WMO officials, Tejas “demonstrated that there is no violation of emissions “with respect to mentioned standards.
Sharing technical data findings, Roy said they matched those in Maharashtra. Interference faced by Airtel is not due to Tejas’ radios breaching out-of-band emission limits but because Airtel sites are positioned very close to BSNL towers “without adequately maximizing coupling losses”, Roy wrote.
He said BSNL’s B05 radios meet standards “with very good margin,” but Airtel’s B08 uplink is experiencing a higher noise floor due to low coupling loss between closely located sites.
To address this, BSNL has deployed antennas with built-in triplexer filters at over 1,000 sites. WMO and WPC have validated these installations, Roy said.
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