Summary

  • ACMA has implemented railway mobile radio rules for 1900–1910 MHz, with coordination distances that fall from 70 km to 5 km when receiver selectivity or advance notice meets the rule.
  • The fallback notice is a real planning instrument: it names affected receivers, calculations, transmitter details and start date, and resets if the station changes.

A railway radio network has to talk along the track without barging into the mobile networks next door. Australia has given railway mobile radio (RMR) 10 MHz at 1900–1910 MHz. Existing 2 GHz base-station receivers sit just above it, at 1920–1980 MHz. ACMA’s solution is not a polite request to “coordinate early” and a hope that everyone brings a spreadsheet. It is a set of distances, receiver tests and a two-year clock.

The rules came out of a planning process that began in 2021. ACMA’s July 2026 outcome implements RALI MS51 for railway radio, updates RALI FX19 for indoor short-range wireless broadband and changes the class-licence and tax instruments. The broader band plan keeps 1880–1900 MHz for class-licensed short-range broadband, allows indoor-only apparatus-licensed services across 1900–1920 MHz, and preserves some regional and remote arrangements. Rail has the narrower slice.

The sharpest problem is old equipment. ACMA expects new 2 GHz base stations to meet the enhanced-selectivity specification in ETSI TS 103 807; not every installed receiver does. RMR and mobile operators are expected to exchange receiver parameters and agree an upgrade timeline. If that collaboration stalls, the rail operator has a defined fallback: notify every affected 2 GHz licensee with a receiver registered within 70 km, two years before the proposed transmitter is assigned.

That notice has to do more than announce an ambition. It must list receivers that fail the coordination test, show the assumptions and results behind the calculations, and give the planned transmitter’s location, operating parameters and start date. Change the transmitter details and the two-year clock starts again. The rule makes the runway useful by making it specific.

The two distances are not competing estimates of how far interference travels. For older receivers, the coordination perimeter can reach 70 km. It contracts to 5 km for receivers licensed after the rules commence, receivers confirmed to meet enhanced selectivity, or older receivers covered by valid two-year notice. Coordination can pass against the prescribed protection criteria or where the affected licensee agrees. The distinction is between which installations need a closer look and what the technical calculation permits.

There is a governance split inside the engineering. The Australasian Railway Association coordinates access to the 10 MHz rail slice; an accredited person performs the technical coordination. ACMA says this industry-led arrangement should improve use of scarce bandwidth, while retaining the option to reassess the ARA’s role as wider rail reforms proceed. Access allocation and interference assessment are separate jobs, even when both decide whether a transmitter can move forward.

The indoor broadband rules show why “adjacent” is not a synonym for “irrelevant”. ACMA changed its building-penetration assumption from 20 dB to 14 dB, which increased a proposed short-range broadband coordination distance to 28 km. Operators of those stations still have a no-interference/no-protection obligation toward 2 GHz receivers. A few decibels in a model can redraw a very large map.

ACMA’s coexistence assessment is theoretical because the international railway-radio deployment record is small. The agency says it will monitor implementation and may revise the coordination provisions. The first useful evidence will be operating stations, actual receiver characteristics and observed coexistence; the paper does not yet contain that record.

Sources