RALI LM8 - Frequency Assignment Requirements for the Land Mobile Service | ACMA

RALI LM8 - Frequency Assignment Requirements for the Land Mobile Service

Radiocommunications Assignment and Licensing Instruction (RALI) LM8 “Frequency Assignment Requirements for the Land Mobile Service” - available in Word (287kB) or PDF (456kB) formats. For ease of reference, the frequency-distance constraints of Annex C are consolidated in this excel workbook. Also included are calculated frequency-distance values before a number of simplifications were made as a result of consultation on IFC 42/2014.

September 2018 Consultation Draft

The ACMA is consulting on proposed updates to LM8 (for details see 2018 issues for comment web page). The proposed updates are to:

To assist future work, the ACMA is also seeking industry views on options for further improving LM8 so that it is reflective of current technologies, provides greater flexibility in frequency assignment and improves spectrum utilisation. Possible options that might lead to improvement which industry might wish to consider include:

  • Revising adjacent channel performance by accepting higher interference thresholds in the adjacent channel domain (e.g. -110 dBm)
  • Coordination based on interference threshold (protection ratio) of service areas with possibly reduced service areas
  • Parameter based coordination. For example, rather that the notional antenna height of 200 metres, coordinate based on installed base station antenna height.

Background

RALI LM08 “Frequency Assignment Requirements for the Land Mobile Service” provides frequency assignment policy and coordination procedures for single and two frequency land mobile systems employing angle and digital modulation methods.

The RALI has been developed primarily for ACMA and accredited frequency assigners. It is also a useful guide for land mobile system planners. The RALI is based on relevant ITU-R work, the Australian experience in this field, and other studies conducted by the ACMA and its predecessors.

The RALI currently applies to angle and digital modulated systems in the VHF Mid Band (70-87.5 MHz), VHF High Band (148-174 MHz) and 400 MHz band using 6.25 kHz, 12.5 kHz and 25 kHz channel bandwidths. It covers both high power (LMRS) and low power (LPMRS) systems, and both single frequency and two frequency systems. The RALI also covers 800 MHz trunked systems using 25 kHz channels.

RALI LM8 was last updated on 11 July 2016 to facilitate harmonised government spectrum area licensing.

June 2015 Update

Following public consultation (see IFC 42/2014: Proposed updates to RALI LM8 land mobile service frequency assignment requirements) updates were made to LM8 in 2015. Along with the discussion paper (Word 592 kB), the rationale for the proposed updates was contained in spectrum planning report SPP 8/2014: Derivation of 400 MHz band land mobile frequency distance constraints used in RALI LM8 (Word 630kB).

In consideration of comments received and follow up discussions, changes were made from the consultation draft to clarify arrangements for supplementary base stations, height power restrictions and intermodulation calculations. Changes were also made to the frequency-distance constraints. In summary these are:

  • Frequency-distance constraints are now symmetrical and based on worst case values. That is, values for new 6.25 kHz to existing 12.5 kHz are the same as new 12.5 kHz to existing 6.25 kHz with worst case values being used.
  • For low powered systems, to address concerns about small separation distances in low powered systems when channel bandwidths overlap, in such circumstances distances have been set at 10 km.
  • Adjusting 1st adjacent channel separation for 12.5 and 25 kHz high powered two frequency systems to be 0 km. The rationale being that either performance will be better than modelled and any degradation in adjacent channel performance will be limited to mobile receivers at the edge of the 40 km service area (i.e. 37 to 40 km) in close proximity to the unwanted base station.
  • Reference levels for 25/12.5 kHz systems are to be the same. For 6.25 kHz systems levels will be adjusted by 3 dB in recognition of smaller bandwidth.
  • Calculating separation distances by determining a reference propagation loss at the co-channel separation distance and using the FDR values to determine what loss (and hence distances) are required at other frequency separations.

Last updated: 28 September 2018