RALI FX14 - 3.4 GHz Point-To-Multipoint For Wireless Local Loop provides information about, and describes procedures for, the frequency coordination and licensing of fixed point-to-multipoint services in the 3.4 - 3.6 GHz band generally intended for WLL services.
Prior to 1995 the Australian Radiofrequency Spectrum Plan arrangements in the 3.4 GHz band provided a primary allocation to the radiolocation service (mainly for defence purposes) and secondary allocations to the fixed service, the fixed-satellite service (space-to-Earth), the mobile service and the amateur service.
In late 1995 the former ACA became aware of interest in providing Wireless Local Loop (WLL) services in the 3.4 GHz band (3.4 - 3.6 GHz). Following consideration, it responded to this interest by upgrading the fixed service allocation in that band to primary status. In the early months of 1997 arrangements were put in place to permit apparatus licensing of fixed point-to-multipoint (P-MP) systems. (At that stage the systems were described as Fixed Radio Access (FRA) systems). Later, in September 1997, RALI FX14 - 3.4 GHz Point-To-Multipoint For Wireless Local Loop was released. That document codified the apparatus licensing and co-ordination arrangements for these P-MP systems.
In March 1998 Embargo 27 was applied to limit apparatus licensing of new systems in the band. (For current spectrum embargoes see RALI MS03). The Embargo prevented new assignments in the frequency ranges 3.425-3.442 & 3.475-3.492 GHz in preparation for a potential price based frequency allocation. Further changes to FX14 saw the addition of coordination procedures relating to specific embargoed areas and protection of Department of Defence services. References to 'WLL' were removed due to the 'narrowness' of that term, in favour of a more general category of point-to-multipoint services.
In September 2009, the spectrum access limitation previously imposed in this RALI was removed. The limitation basically stated that - no applicant was permitted to access more than half of the 2 x 17.5 MHz sub-bands in total in any one area. The ACMA was of the view that this restriction was no longer necessary mainly due to the availability of other frequency bands that could also be used to provide similar services including broadband wireless access. After canvassing the opinion of existing licensees the ACMA decided to remove the spectrum access limit.
Spectrum Re-allocation Declaration
In April 2000 the Minister for Communications, Information Technology and the Arts declared that the part of the spectrum from 3425 - 3492.5 MHz and 3542.5 - 3575 MHz was subject to re-allocation by issuing spectrum licences. For details see the Radiocommunications (Spectrum Re-allocation) Declaration 2000. FX14 (Sequence 159) was updated to describe coordination requirements between apparatus licensed P-MP services and the spectrum licensed areas. (Generally speaking, apparatus licences must not be issued in spectrum licensed bands within spectrum licence areas - Embargo 26 lists all spectrum licensed bands in one convenient reference.)
In late 2000, following a price based allocation process, spectrum licences were issued for most of the areas specified in the Declaration. As well, Embargo 27 was withdrawn.
During 2003 the former ACA was asked to clarify some parts of FX14, specifically in relation to possible propagation models and site sense issues.
RALI FX14 specifies co-frequency reuse distances in excess of 90 km or where the path loss can be demonstrated to be equal to or in excess of 165 dB. FX14 incorporates a free space path loss model (see Annex B). It also advises that additional path loss can be gained through terrain shielding, in which case the re-use distance can be reduced. Conversely, very flat or over-water paths might actually require a larger re-use distance than 90 km. Due to the variety of terrain types and propagation models that might be used the methodology of FX14 was to define a path loss requirement and provide assigners with the flexibility to select a suitable methodology (including an appropriate path loss model) in assessing the co-frequency reuse distance.
One possible Methodology:
An example of one possible methodology that could be used to determine path loss is based on the path loss calculations detailed in Rec. ITU-R P 452. This methodology can be found at Example Methodologies for Demonstrating the Existence of Adequate Point-to-Area Path Loss for Co-Channel Re-use, Adjacent Channel Re-use and Coordination with Spectrum Licensed Space (PDF 15 kb).
Note - as stated above, assigners are free to use other methodologies provided that they satisfy the overall 165 dB path loss condition.
FX14 was developed around a frequency division duplex (FDD) model hence maintaining site sense (ie, consistent Base Tx/Base Rx orientation) is important for spectrum efficiency. While a particular site sense direction is not explicitly defined in FX14 the use of the 3.4 GHz band has evolved such that the 3425-3442.5 MHz segment is used for base receive/remote transmit and 3475-3492.5 MHz segment is used for base transmit/remote receive. Assigners should follow this convention as far as is practicable.
Spectrum Licensed Areas:
Frequency coordination with 3.4 GHz spectrum licensed areas enables an apparatus licensed P-MP station to be operated adjacent to spectrum licensed areas provided that the base station is located in a position to achieve a path loss to the nearest point 20 km inside the adjacent spectrum licensed area that is equal or greater than 165 dB. The reference in section 7.4.4 of FX14 provides information of areas where FX14 apparatus licensed services may be deployed. For images of the relevant spectrum licensed areas see: overview map (PDF 45kb) or detailed maps.
Use of Alternative Technologies:
During 2007 the ACMA was approached with proposals to deploy Time Division Duplex (TDD) P-MP base stations and associated subscriber stations under apparatus licences in locations outside spectrum licensed areas in the 3.4 GHz band. The ACMA has decided to allow the use of TDD equipment in the 3.4 GHz band under the following conditions;
- TDD P-MP systems must be able to meet coordination arrangements set out in RALI FX14 for two frequency FDD systems to qualify for licence issue.
- TDD P-MP systems may only be deployed in the upper segment of the available 3.4 GHz band (3475-3492.5 MHz). As noted above this segment is nominally used for base transmit/remote receive operation.
At this stage the lower segment of the band (3425-3442.5 MHz) is not available for use by TDD systems. Use of the lower segment is being considered by ACMA, however, the nominal presence of base receivers requires a reassessment of the protection requirements and coordination arrangements for this band. Thus the lower segment of the band may become available after the assessment has been completed.
- The deployment and operation of TDD P-MP systems must not cause unacceptable interference to other licensed radiocommunications systems (including subscriber equipment) operating in the 3.4 GHz band. In the event of interference, it is required that the interfering TDD P-MP systems be modified or cease operation to resolve the interference. In determining whether unacceptable interference is being caused to the operation of other radiocommunications devices, ACMA would take into consideration such things as: the disruption, degradation or reduction in data throughput of the other service; the loss or reduction of signal availability or the degradation in the quality of the recovered wanted signal.
- A TDD P-MP system apparatus licensee operating in the 3.4 GHz band must accept interference from any currently deployed FDD P-MP systems or any future deployments of FDD P-MP systems.
- Individual licence conditions for TDD systems will be applied to licences to reflect the requirements in points 1 to 4 above.