Hong Kong’s largest mobile operator, HKT, called on the telecoms regulator to use the 700MHz band to boost coverage in underground train stations, pointing to new research and field tests which indicate the band can be used without interfering with signals above ground.

The 700MHz frequency is currently used for TV broadcasting in the territory.

Citing a study by City University of Hong Kong which found the 900MHz band signals transmitted at underground stations do not penetrate through to ground level, HKT wants the Office of the Communications Authority (OFCA) to review the use of the 700MHz frequency band for mobile communications inside enclosed location in order “to relieve mobile traffic congestion problems as early as possible”.

HKT has been vocal about its displeasure with the speed OFCA is allocating new spectrum, particularly 5G airwaves.

In its report, the University noted that since the 900MHz and 700MHz bands have similar propagation characteristics, using 700MHz spectrum in underground stations would be unlikely to reach the ground level.

HKT said it performed measurements for 700MHz signals at underground platforms of train stations and no matching signals were detected at any of the test locations.

The regulator last month kicked of public consultations on 5G spectrum allocations in the 26GHz and 28GHz bands, which are also known at mmWave frequencies.