Commonwealth of Australia

Radiocommunications Act 1992

Radiocommunications Advisory Guidelines (Managing Interference from Non-spectrum-licensed Transmitters - 28 GHz and 31 GHz Bands) 1998

THE AUSTRALIAN COMMUNICATIONS AUTHORITY makes the following guidelines under section 262 of the Radiocommunications Act 1992

Dated   11 November  1998.

                                                                                                                        A.J SHAW

Chairman

R HORTON

Deputy Chairman

Australian Communications Authority

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PART 1¾INTRODUCTION

Title

            1.1.  These guidelines are called the Radiocommunications Advisory Guidelines (Managing Interference from Non-spectrum-licensed Transmitters¾28 GHz and 31 GHz Bands) 1998.

Commencement

            1.2.  These guidelines commence on 11 November 1998.

Purpose of these guidelines

            1.3.  The purpose of these advisory guidelines is to manage out-of-band interference by providing for the protection of fixed receivers operating in spectrum covered by spectrum licences issued for the 28 GHz and 31 GHz bands from interference caused by fixed non-spectrum licensed transmitters that are licensed after the issue date of the Radiocommunications Spectrum Marketing Plan (28 GHz and 31 GHz Bands) 1998.

Interpretation

            1.4.  In these guidelines, unless the contrary intention appears:

Act means the Radiocommunications Act 1992.

adjacent channel selectivity means a measure of the ability of the receiver to receive a wanted signal without exceeding a specified degradation in output quality caused by the presence of an unwanted adjacent channel signal.

blocking means a measure of the ability of the receiver to receive a wanted signal without exceeding a specified degradation in output quality caused by the presence of a high level off-tune signal overloading the receiver’s front-end.

emission buffer zone means a zone along the frequency or geographic boundary of a spectrum licence where emission levels of transmitters are reduced to ensure that significant levels of emissions stay within the geographic area and frequency band of the licence.

fixed receiver means a radiocommunications receiver located at a fixed point on land or sea and not established for use while in motion.

in-band, in relation to a transmitter operated under a spectrum licence, means the frequencies within the frequency band of the spectrum to which the licence relates.

incumbent device means a radiocommunications device that has part of:

(a) the frequency band of its spectrum access within the 28 GHz or 31 GHz

     band; and

(b) its location within the area for that band, as designated under section 36, or declared under s.153B, of the Act.

intermodulation immunity means a measure of the ability of a receiver to receive a wanted signal without exceeding a specified degradation in output quality caused by the presence of two or more unwanted signals with a specific amplitude and frequency relationship to the wanted signal frequency.

Register means the Register established under s.143 of the Act.

s.145 determination means the Radiocommunications (Unacceptable Levels of Interference¾28 GHz and 31 GHz Bands) Determination 1998.

spectrum space means a 3 dimensional space consisting of a frequency band and a geographic area.

spurious response immunity means a measure of the ability of the receiver to discriminate between the wanted signal at its nominal frequency and an unwanted signal at any frequency at which the receiver responds.

28 GHz band  means the frequency band 27.5 GHz - 28.35 GHz.

31 GHz band means the frequency band 31 GHz - 31.3 GHz.

            (2) In these guidelines, the range of numbers that identifies a frequency band includes the higher, but not the lower, number.

            (3)  A term used in these guidelines that is defined in the s.145 determination has the same meaning as in that determination.

[NOTES:  1.  The following terms, used in this determination, are defined in the Radiocommunications Act 1992 and have the meanings given to them by that Act:

frequency band                                    interference

ACA                                                       spectrum licence

transmitter.

                2.  The following terms are defined in the Radiocommunications (Unacceptable Levels of Interference - 28 GHz and 31 GHz Bands) Determination 1998 and have the meanings given to them by that Determination:

fixed transmitter]

PART 2¾MANAGING INTERFERENCE FROM FREQUENCY ADJACENT SERVICES

In-band and out-of-band interference

            2.1  Application of:

·      the core conditions of a spectrum licence that relate to maximum levels of emission outside the geographic area, and

·      device boundary criteria (if any are specified);

manages in-band interference by providing reasonable protection to receivers operated in spectrum covered by area adjacent spectrum licences.  These conditions provide protection from interference caused by in-band emission for the entire term of the spectrum licence and over the entire geographic area.

            2.2  Spectrum licensees must accept any in-band interference for a certain period from devices that are operated under non-spectrum licences issued before 2 February 1998 (the start of the re-allocation period).  If the device is an incumbent device, the period is the term of the re-allocation period.  If the device is authorised to use spectrum adjacent to spectrum that is managed under spectrum licensing, the period could possibly be for the full term of the spectrum licence.

            2.3 The core conditions of a spectrum licence that relate to maximum levels of emission outside the frequency band of a licence manage, in a direct manner, in-band interference caused to frequency adjacent-services.  Interference can also be caused to frequency-adjacent services through mechanisms that act indirectly (for example, receiver intermodulation) and usually occur between devices located close to each other at communal sites.  It is not practical to use emission limits to manage this indirect type of interference.  Therefore, the emission limits do not provide protection at the frequency boundaries of a spectrum licence throughout the entire geographic area of a licence.

Out-of-band interference from closely located frequency adjacent devices

            2.4  Out-of-band interference is difficult to predict because the levels and frequencies of unwanted emissions depend on the operating frequencies of transmitters and receivers that are close in terms of both frequency and distance.  In addition, out-of-band interference:

·      can extend for many MHz either side of the frequency boundary of a spectrum licence; and

·      depends on the quality of the receiver as well as the levels of transmitter emission; and

·      cannot be accurately modelled.

Because the interference extends for many MHz, it is possible for devices operating under non-adjacent spectrum licences to interfere with each other.

            2.5  If emission limits were used to manage out-of-band interference for devices in close proximity, the interference modelling inaccuracy would require large probability margins to be added to those limits.  These margins would place severe constraints on use of the spectrum because the frequency boundaries of a licence, at which those limits would have to be applied, extend throughout the entire geographic area of a licence.  Therefore, emission limits that manage out-of-band interference for the entire geographic area of a spectrum licence (including communal sites) cannot be used because they would lead to a severe loss of utility of the spectrum on both sides of the frequency boundary.

            2.6  Instead of making large tracts of spectrum space unusable through the imposition of emission limits, the interference is managed through procedures based on a compatibility requirement for existing receivers.  Because the performance level of receivers both affects the level of interference and is likely to vary widely for receivers operating under spectrum licences, a minimum level of receiver performance should be specified in conjunction with the compatibility requirement.

Recording device details in the Register

            2.7  A receiver will not be afforded protection unless details of the receiver are in the Register.

Mobile devices

            2.8  The compatibility requirement does not apply to mobile devices operating under any type of licence because the mobility of the devices prevents the use of a practical interference management procedure.  Where necessary, spectrum licensees operating receivers will need to employ hardware or siting schemes in accordance with mobile equipment standards for non-spectrum licensed devices to guard against interference caused by those emissions.

PART 3¾MINIMUM LEVEL OF RECEIVER PERFORMANCE

            3.1 The level of interference caused by out-of-band emissions depends on the interference susceptibility of the receiver.  Emission levels from transmitters should not have to be reduced below a point where the performance of the receiver is really the problem.  Therefore, a receiver should have a minimum level of performance such that its susceptibility to interference does not reduce the utility of adjacent licensees’ spectrum beyond what is reasonable.  An estimate of the interference susceptibility of a receiver would be based on its performance in relation to adjacent channel selectivity, blocking, intermodulation immunity and spurious response immunity.  These characteristics are influenced by the RF and IF selectivity of a receiver.  A minimum level of performance for receiver RF and IF selectivity is given in Schedule 1.

PART 4¾COMPATIBILITY REQUIREMENT

            4.1 A non-spectrum licensed fixed transmitter must meet the compatibility requirement in Schedule 2 for a fixed receiver:

            (a) with a reasonable minimum level of performance; and

(b) registered before the issue of the licence under which the transmitter operates; and

(c) operating under a spectrum licence issued for the 28 GHz or 31 GHz band.

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SCHEDULE 1

Clause 3.1

MINIMUM RECEIVER PERFORMANCE LEVEL

1.         RF and IF selectivities

Table 1 sets out the minimum selectivity caused by the sum of the RF and IF selectivities of a receiver operating under a spectrum licence issued for the 28 GHz or 31 GHz band for interfering signals from a transmitter operated under a non-spectrum licence.

·      Column 1 sets out the frequency offset by reference to the upper and lower limits of the frequency band of the spectrum space in which the receiver operates.  A negative offset means that the frequency is inside the frequency band of the licence by the amount of that offset.

·      Column 2 sets out the frequency offset by reference to the upper and lower absolute frequency limits of the effective occupied bandwidth of the transmitter that communicates with the receiver.

Table 1. Receiver RF+IF filter characteristics.

2.         RF selectivity

Table 2 sets out the minimum RF selectivity of a receiver between the antenna and the antenna connector of the equipment.  The frequency offsets are specified with reference to the upper and lower limits of the frequency band of the spectrum licence under which the receiver operates.  A negative offset means that the frequency is inside the frequency band of the licence by the amount of that offset.

Table 2. Receiver RF filter characteristics.

3.         Antenna performance

The minimum level of performance of an antenna for a receiver located at the phase centre of the antenna is a gain of 15 dBi, a feeder loss of 0 dB and a combiner loss of 0 dB in all directions.

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SCHEDULE 2

Clause 4.1

COMPATIBILITY REQUIREMENT

The compatibility requirement for a fixed receiver operating under a spectrum licence to be provided by a non-spectrum licensed transmitter is:

·      an output quality equivalent to a wanted to unwanted signal level ratio that is not less than 14 dB for more than 1% of the time in any 1 hour period; and

·      with the wanted signal never less than -92 dBm; and

·      when measured within a 1 MHz rectangular bandwidth that is within the frequency band of the spectrum licence.

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