Radiocommunications Advisory Guidelines (Managing Interference from Spectrum Licensed Transmitters – 2.5 GHz Mid Band Gap) 2023

The central concept is the 2.5 GHz mid band gap: the frequency band 2570 MHz to 2620 MHz. It is flanked by the 2.5 GHz lower band (2500-2570 MHz) and the 2.5 GHz upper band (2620-2690 MHz). The instrument defines in-band and out-of-band frequencies relative to the licence type. For spectrum licences, in-band is the part of spectrum the licence authorises; for apparatus licences, it is the specified frequency limits or centred bandwidth. Out-of-band is any other frequency. This distinction is key because interference from out-of-band emissions, blocking, and intermodulation are the risks the guidelines address. Fixed receivers and fixed transmitters are defined as devices located at a fixed point on land or sea, not designed for use while in motion. The instrument distinguishes between spectrum licensed receivers (operating under spectrum licences in the 2.5 GHz band, used for WAS) and apparatus licensed receivers (used for fixed services, typically point-to-point links). WAS (wireless access service) involves fixed base stations transmitting to lower-power mobile user equipment, often providing public data network access. FDD (frequency division duplex) is the duplexing method used for the paired lower and upper bands. The instrument also introduces the ARQZWA (Australian Radio Quiet Zone Western Australia), a protected area for radio astronomy, defined by the Radiocommunications (Australian Radio Quiet Zone Western Australia) Frequency Band Plan 2023. An area within 70 km of the radio astronomy site is excluded from the geographic area of 2.5 GHz mid band gap spectrum licences. The instrument references key external documents: RALI FX 3 (Microwave fixed services frequency coordination) and RALI MS 32 (Coordination of Apparatus Licensed Services Within the Australian Radio Quiet Zone Western Australia). These are ACMA published instructions that contain detailed technical methods and limits. Protection requirements for apparatus-licensed point-to-point stations are said to be in RALI FX 3. For spectrum-licensed receivers in the 2.5 GHz band, the protection requirements are in a companion instrument: the Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap) 2023. The instrument also references ITU‑R Recommendations, notably P.1144 on propagation methods, but notes that other published propagation models may be suitable. The instrument is structured with background sections (7, 8, 10, 12) explaining the context for each category, followed by protection requirement sections (9, 11, 13). Part 3 covers spectrum-licensed receivers, Part 4 apparatus-licensed fixed service receivers, and Part 5 ARQZWA coordination (though the part numbers are only mentioned in section 7, not in the headings of the later sections). The instrument also defines point to point station by reference to the Radiocommunications (Interpretation) Determination 2015 or its replacement.

The primary affected parties are licensees of 2.5 GHz mid band gap spectrum licences. These are entities authorised to operate transmitters in the 2570-2620 MHz band. They must consider the interference management expectations set out in the guidelines when deploying and operating their transmitters. Second, licensees of spectrum licences in the 2.5 GHz lower and upper bands (2500-2570 MHz and 2620-2690 MHz) are affected as recipients of potential interference from mid band gap transmitters. Their fixed receivers are protected under the guidelines if they were first included in the Register before the mid band gap transmitter was registered. Third, apparatus licensees who operate fixed point-to-point stations in or adjacent to the 2.5 GHz mid band gap are affected. These are typically special-application links in remote locations, with few licences issued. Their protection requirements are set out in RALI FX 3. The instrument notes the ACMA has generally stopped issuing apparatus licences in the 2.1 GHz band (except 2.2 GHz), which suggests a declining number of such links over time. Fourth, radio astronomy operators within the ARQZWA are affected, as the guidelines require coordination using methods from RALI MS 32 for mid band gap transmitters near the quiet zone. The site itself is in remote central Western Australia, and an area within 70 km is excluded from mid band gap spectrum licences, so only licensees in adjacent areas are affected. Fifth, the ACMA is affected as the agency that may take the guidelines into account when determining interference disputes. The instrument also affects other spectrum-licensed, apparatus-licensed, and class-licensed operators who may suffer interference, as the guidelines clarify the ACMA’s stance on protection of certain receivers but not all. The instrument does not cover interference to mobile receivers or to devices operated under class licences, except indirectly through the general interference provisions of the Act. The guidelines also affect manufacturers and suppliers of radiocommunications equipment to the extent that compliance with the guidelines may influence equipment design or site selection. Finally, legal and compliance professionals who advise on spectrum licence conditions and interference risk will need to factor these guidelines into their assessments, even though the instrument is advisory. The small number of participants in the 2.5 GHz mid band gap (given its specialised nature) means the direct compliance burden is likely concentrated among a handful of licensees, but the precedent set for interference management in spectrum-licensed bands may have broader industry implications.

The instrument does not impose statutory duties. It is advisory. However, it articulates expectations that, if followed, reduce the risk of an ACMA determination that a transmitter is causing unacceptable interference. The key expectations are:

• For a fixed receiver operating under a spectrum licence in the 2.5 GHz band that was first registered before the mid band gap transmitter, a licensee of a mid band gap spectrum licence should apply the compatibility requirement and notional receiver performance levels specified in the companion instrument (Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap) 2023). Additionally, coordination is typically necessary for outdoor fixed transmitters located within 200 metres of such a receiver.

• For an apparatus-licensed point-to-point station used for fixed link systems that was first registered before the mid band gap transmitter, the protection requirements are those in RALI FX 3.

• For coordination with the ARQZWA, licensees of mid band gap spectrum licences in areas adjacent to the quiet zone should use the methods and limits set out for apparatus licensees in RALI MS 32.

The instrument expressly preserves the right to negotiate and implement other protection requirements with other persons. This means parties can agree to different interference management arrangements, potentially less stringent or more tailored, without breaching the guidelines. However, if a dispute arises and the ACMA is called to determine interference, the ACMA may take the guidelines into account. Following the guidelines gives a licensee a strong argument that they have managed interference appropriately. Conversely, deviating from the guidelines (even by agreement) may invite scrutiny, though a written agreement with the affected party would likely be given weight.

Licensees also have the right to rely on the Register to identify pre-existing fixed receivers. The guidelines note that location and antenna details of such receivers can be found in the Register, and coordination is typically necessary for transmitters within 200 metres. This implies a duty of reasonable inquiry, though not a strict obligation.

The instrument also implies that licensees have the right to use suitable propagation models (including ITU‑R P.1144 or other published models) to estimate path loss, without being locked into a single method. This flexibility reduces compliance cost but also creates uncertainty about which model the ACMA would accept.

In summary, the instrument creates soft expectations rather than hard duties. The real duties arise from the Radiocommunications Act 1992 itself: the prohibition on causing interference (subject to licence conditions) and the requirement to comply with spectrum licence technical frameworks. The guidelines provide a safe harbour of sorts, but they do not immunise a licensee from liability if interference occurs despite compliance.

The instrument itself does not prescribe penalties. It is an advisory guideline made under section 262 of the Act, which allows the ACMA to issue guidelines but does not create civil penalty provisions or offences. Enforcement for interference flows from the Radiocommunications Act 1992. Under that Act, causing interference that contravenes a licence condition or the spectrum plan can result in directions, licence suspension or cancellation, civil penalties, or injunctions. The ACMA has powers to issue remedial directions, impose fines, and seek court orders. The guidelines become relevant in enforcement because the ACMA will likely consider whether a licensee has acted in accordance with them. If a mid band gap transmitter causes interference to a protected fixed receiver and the licensee did not follow the guidelines (e.g., did not coordinate within 200 metres or did not apply the companion protection requirements), the ACMA would have a stronger basis to find the interference unacceptable. Conversely, if the licensee followed the guidelines, the ACMA may still find interference but may be more inclined to attribute it to the affected receiver’s characteristics or suggest alternative remedies. The notes in the instrument (e.g., section 7(5)) explicitly state the ACMA may take the instrument into account in determining interference. This does not create a presumption of compliance; it is merely a factor. The instrument also does not specify any transitional provisions or grace periods, so a new mid band gap licensee must immediately consider existing registered receivers. Failure to coordinate could expose the licensee to enforcement action from the outset. There are no monetary penalties specified in the guidelines, but the costs of enforcement (legal fees, potential licence variation, or shutdown) could be significant. The instrument also does not address penalties for non-compliance with the companion instrument (Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap) 2023), which is similarly advisory. Overall, the enforcement risk is indirect but real: the guidelines shape the ACMA’s discretionary enforcement against the background of the Act’s interference provisions. Prudent licensees will treat them as de facto requirements, even though they are not legally binding.

The instrument is made under section 262 of the Radiocommunications Act 1992. It is a legislative instrument (as indicated by its registration on the Federal Register of Legislation), but it is advisory, not mandatory. It interacts with several other instruments and documents:

• Radiocommunications Act 1992: The foundational statute. The guidelines provide guidance on how the ACMA may interpret interference provisions under the Act, but they do not override the Act. Licence conditions, the spectrum plan, and the Act’s prohibitions remain paramount.

• Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap) 2023: The companion instrument that specifies protection requirements for spectrum-licensed receivers in the 2.5 GHz band. The present guidelines incorporate those requirements by reference (section 9). Both instruments are advisory and should be read together.

• RALI FX 3 (Radiocommunications Assignment and Licensing Instruction FX 3): This is an ACMA published instruction for microwave fixed services frequency coordination. The present guidelines state that protection requirements for apparatus-licensed point-to-point stations are in RALI FX 3. RALI FX 3 is likely used by apparatus licensees for coordination and may have its own technical limits.

• RALI MS 32 (Radiocommunications Assignment and Licensing Instruction MS 32): This instruction covers coordination of apparatus-licensed services within the ARQZWA. The present guidelines require mid band gap licensees to coordinate using the methods and limits in RALI MS 32.

• Radiocommunications (Australian Radio Quiet Zone Western Australia) Frequency Band Plan 2023: Defines the ARQZWA and its geographic extent. The present guidelines reference this plan and note that the area within 70 km of the radio astronomy site is excluded from mid band gap spectrum licences. Coordination is required for adjacent areas.

• Radiocommunications (Interpretation) Determination 2015: Referenced for the definition of “point to point station”.

• Spectrum Plan: Made under the Act, defines fixed service and radio astronomy service, among other terms. The present guidelines adopt those definitions.

• ITU‑R Recommendations: The guidelines recommend using ITU‑R P.1144 for propagation modelling, but note other models may be suitable. This interaction is soft; the guidelines do not mandate compliance with any ITU‑R recommendation.

• Class licences: The instrument notes that receivers operated under class licences may also suffer interference, but the guidelines are focused on spectrum-licensed and apparatus-licensed receivers. Class-licensed operators are not given specific protection requirements, but the general interference provisions of the Act still apply.

• State and territory laws: Not directly relevant, but land-use planning and environmental laws may affect tower siting, which can interact with coordination requirements.

The instrument also repeals the 2012 version, so the only operative guidelines for this band are now the 2023 versions. The repeal is clean, with no transitional provisions. This means any existing coordination arrangements or reliance on the 2012 guidelines should be reviewed.

This instrument is the first version of the 2023 guidelines. It repeals and replaces the Radiocommunications Advisory Guidelines (Managing Interference from Transmitters - 2.5 GHz Mid-band Gap) 2012 (F2012L02555). The source text does not provide details of the 2012 guidelines’ content or amendments, but the repeal suggests the ACMA considered updates necessary, likely due to changes in spectrum allocation, technical standards, or the establishment of the ARQZWA Frequency Band Plan in 2023. There is no indication of any other amendments to the 2023 instrument itself. As a legislative instrument, any future amendment would be published on the Federal Register of Legislation. The instrument’s commencement provision (section 2) ensures it takes effect the day after registration, which is typical for ACMA advisory guidelines. The repeal of the 2012 instrument means that any prior guidance is no longer in effect, so licensees must rely solely on the 2023 version. There is no savings provision for existing coordination agreements under the old guidelines, but since the guidelines are advisory, contractual agreements made under the old guidelines remain valid as private arrangements. However, if the ACMA were to consider compliance with the guidelines, it would likely apply the current version. The absence of an amendment history within the instrument means that the reader must check the FRL for any subsequent changes. Given the technical nature of the band and the limited number of licensees, major amendments are unlikely unless there is a reallocation of the mid band gap or changes to the ARQZWA boundaries.

The source text does not mention any litigation involving the 2012 or 2023 guidelines. As advisory guidelines, they are unlikely to be directly challenged in court. However, they may be referenced in proceedings under the Radiocommunications Act 1992 concerning interference disputes. For example, if a mid band gap spectrum licensee is alleged to have caused interference, the guidelines could be tendered as evidence of what the ACMA considers acceptable practice. A court or tribunal (such as the Administrative Appeals Tribunal) might consider whether the licensee’s conduct was consistent with the guidelines, though the guidelines are not binding. There is no reported appellate consideration of the 2012 guidelines in the public domain. Trade practices litigation or nuisance claims between private parties could also reference the guidelines as industry standards. Because the instrument is relatively new (2023), there is no litigation history specific to it. The lack of litigation suggests that either the 2012 guidelines were effective in preventing disputes, or that disputes were resolved without public litigation. Future disputes could arise if mid band gap licensees deploy transmitters that cause interference to WAS receivers in the lower or upper bands, particularly if coordination distances (200 metres) are not respected. The ARQZWA coordination requirements could also be a source of dispute if radio astronomy observations are degraded. Given the concentration of licensees, disputes may be rare but could be high-stakes. Legal professionals should monitor the ACMA’s enforcement decisions and any tribunal or court rulings that interpret the guidelines’ relevance.

Several aspects of the instrument could trap unwary licensees or advisers:

• Advisory but effectively mandatory: The instrument says the ACMA “may take this instrument into account” in interference determinations. While not legally binding, in practice, the ACMA will expect compliance. A licensee who ignores the guidelines faces a higher risk of an adverse finding. The safe harbour is not absolute, but deviation is risky.

• The 200-metre coordination distance is stated as “typically necessary” for outdoor fixed transmitters. This is not a hard rule; it is a guideline. However, a licensee who assumes coordination is unnecessary beyond 200 metres may be wrong if topography or receiver sensitivity requires more. Conversely, coordination within 200 metres may still be insufficient if the transmitter power is high. The instrument does not specify exceptions or adjustments.

• Protection requirements depend on the order of registration. Section 9 protects fixed receivers “first included in the Register before the registration of a fixed transmitter” under a mid band gap licence. This creates a priority race. A mid band gap licensee should check the Register at the time of registration; later changes (e.g., new fixed receivers registered after the transmitter) may not be protected under these guidelines. But the Act’s general interference provisions may still protect later receivers.

• The companion instrument is not included in the text of these guidelines. Section 9 incorporates by reference the Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap) 2023. Licensees must obtain and read that separate instrument to understand the specific compatibility requirement and notional receiver performance levels. Failing to do so could result in non-compliance with the ACMA’s expectations.

• RALI FX 3 and RALI MS 32 are living documents. The guidelines reference them as in force from time to time. Changes to those instructions automatically affect the protection requirements, without amendment to these guidelines. Licensees must monitor updates.

• No grandfathering for existing transmitters. The 2012 guidelines are repealed, but the 2023 guidelines apply from commencement. There is no transitional provision for transmitters already deployed under the 2012 guidelines. Those transmitters may now be subject to different coordination expectations, particularly for ARQZWA (which was established by a 2023 plan). Licensees should review existing operations.

• The instrument does not address mobile user equipment. The protection is for fixed receivers only. Mobile devices (e.g., handsets) are not covered by these guidelines, even though they may be affected by interference from mid band gap transmitters. Licensees may still face claims from mobile users under the Act’s general provisions.

• Negotiation of alternative protection requirements is permitted, but the ACMA is not bound by private agreements. Section 7(6) says the instrument does not prevent negotiation. However, if a dispute goes to the ACMA, it could still find interference unacceptable even if the parties had agreed to lesser protection. The guidelines do not create a defence of “consent”.

• Propagation model flexibility creates uncertainty. The instrument says ITU‑R P.1144 or other published models may be suitable. But there is no accepted list of models. Two parties may use different models and reach different interference predictions, leading to disputes.

• The 70 km exclusion zone for ARQZWA is not a complete protection. Licensees adjacent to the exclusion zone must still coordinate using RALI MS 32. They cannot assume they are far enough away.

Compliance with these advisory guidelines involves a series of checks and coordination steps. Since the guidelines are not mandatory, licensees may choose alternative approaches, but to minimise regulatory risk, the following steps are recommended:

1. Identify pre-existing protected receivers: Before registering a fixed transmitter under a 2.5 GHz mid band gap spectrum licence, search the Register for:

   • Fixed receivers operating under spectrum licences in the 2.5 GHz band (lower and upper) that were included in the Register before the transmitter’s registration.
   • Apparatus-licensed point-to-point stations (fixed services) in or adjacent to the mid band gap that were similarly pre-existing.
   • Note the location and antenna details of these receivers, which are available from the Register.

2. Apply protection requirements for spectrum-licensed receivers: For each pre-existing fixed receiver in category (a), obtain the Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 2.5 GHz Mid Band Gap) 2023. Apply the compatibility requirement and notional receiver performance levels specified therein. For outdoor fixed transmitters located within 200 metres of such a receiver, coordinate with the licensee of the receiver (e.g., adjust transmitter power, antenna pattern, or frequency). The 200-metre distance is a typical threshold; longer distances may be needed depending on terrain and propagation.

3. Apply protection requirements for apparatus-licensed point-to-point stations: For each pre-existing apparatus-licensed station, obtain RALI FX 3 and follow its coordination methods and limits. This may involve calculating interference levels and agreeing on parameters with the affected licensee.

4. Coordinate with ARQZWA: If the proposed transmitter is in an area adjacent to the ARQZWA (as defined in the Radiocommunications (Australian Radio Quiet Zone Western Australia) Frequency Band Plan 2023), obtain RALI MS 32 and use its methods and limits to coordinate the station. Note that an area within 70 km of the radio astronomy site is excluded from mid band gap spectrum licences, so no transmitter is permitted there; coordination applies only to adjacent areas.

5. Select a suitable propagation model: Use ITU‑R Recommendation P.1144 to guide selection of a propagation method appropriate for the frequency, terrain, and climate. Alternatively, use another published model that is defensible. Document the model and parameters used for future reference.

6. Negotiate alternative protection if desired: If the above steps result in unacceptable constraints, consider negotiating alternative protection requirements with the affected receiver licensee. Document any agreement in writing. However, be aware that the ACMA is not bound by such agreements and may still consider interference unacceptable.

7. Maintain records: Keep a file of all coordination efforts, calculations, correspondence, and agreements. This will be crucial if the ACMA later investigates interference complaints.

8. Monitor changes: After deployment, monitor the Register for any new fixed receivers that may be registered. If a new receiver is registered after the transmitter, it is not protected under these guidelines, but you should still consider the Act’s general interference provisions. Also track amendments to RALI FX 3, RALI MS 32, and the companion guidelines, as their requirements may change.

9. Review existing operations: If you operated under the 2012 guidelines, review your coordination against the 2023 guidelines, especially any changes to the ARQZWA coordination requirement. Update agreements if necessary.

Following these steps does not guarantee immunity from interference disputes, but it aligns with the ACMA’s stated expectations and reduces enforcement risk. The costs of compliance include staff time, potential engineering modifications, coordination delays, and possible constraints on transmitter placement. For a small number of licensees in a specialised band, these costs are likely manageable but should not be underestimated.