Radiocommunications Advisory Guidelines (Managing Interference to Receivers – 2.5 GHz Mid-band Gap) 2012
Radiocommunications Act 1992
The Australian Communications AND MEDIA Authority makes these Advisory Guidelines under section 262 of the Radiocommunications Act 1992.
Dated 13th December 2012
Chris Chapman
[signed]
Member
Richard Bean
[signed]
Member/General Manager
Australian Communications and Media Authority
Part 1 Preliminary
1.1 Name of guidelines
These guidelines are the Radiocommunications Advisory Guidelines (Managing Interference to Receivers – 2.5 GHz Mid-band Gap) 2012.
1.2 Commencement
These guidelines commence on the same day as the Radiocommunications Spectrum Conversion Plan (2.5 GHz Mid-band Gap) 2012.
Note All legislative instruments and compilations are registered on the Federal Register of Legislative Instruments kept under the Legislative Instruments Act 2003. See http://www.frli.gov.au.
1.3 Purpose
(1) The purpose of these guidelines is to:
(a) manage in‑band and out‑of‑band interference, by providing compatibility requirements for registered fixed receivers operating under spectrum licences issued for the 2.5 GHz Mid-band Gap; and
(b) provide protection from interference caused by fixed transmitters operated under apparatus licences, class licences or spectrum licences issued after the commencement of the Radiocommunications Spectrum Conversion Plan (2.5 GHz Mid-band Gap) 2012.
(2) These guidelines should be used by operators of spectrum‑licensed services and apparatus‑licensed services in the planning of services and in the resolution of interference cases.
(3) These guidelines do not prevent a licensee negotiating other protection requirements with another licensee.
1.4 Interpretation
(1) In these guidelines, unless the contrary intention appears:
2.5 GHz Mid-band Gap means the frequency band 2570 MHz ‑ 2620 MHz.
Act means the Radiocommunications Act 1992.
adjacent channel means a channel with a centre frequency offset on either side of the assigned channel frequency of the occupied channel by a specific frequency relation.
adjacent channel selectivity or ACS means a measure of the ability of the radiocommunications receiver to receive a wanted signal without exceeding a specified degradation in output quality due to the presence of an unwanted adjacent channel signal.
blocking means a measure of the ability of a radiocommunications receiver to receive a wanted signal in the presence of a high level unwanted interferer on frequencies other than those of the adjacent channels.
communal site has the meaning given by Schedule 1 of the Radiocommunications (Interpretation) Determination 2000.
emission buffer zone means a zone along the frequency or geographic boundary of a spectrum licence where emission levels of radiocommunications transmitters are reduced to ensure that significant levels of emissions stay within the geographic area and frequency band of the licence.
in‑band means:
(a) for a radiocommunications transmitter or radiocommunications receiver operated under a spectrum licence, the frequencies within the frequency band in which the operation of those radiocommunications devices is authorised under the licence; and
(b) for a radiocommunications transmitter or radiocommunications receiver operating under an apparatus licence, the frequencies within the lower frequency limit and the upper frequency limit specified in the licence.
intermodulation response rejection means a measure of the ability of a radiocommunications receiver to receive a wanted signal in the presence of two or more unwanted signals with a specific amplitude and frequency relationship to the wanted signal frequency.
out‑of‑band means:
(a) for a radiocommunications transmitter or radiocommunications receiver operated under a spectrum licence, the frequencies outside the frequency band in which the operation of those radiocommunications devices is authorised under the licence; and
(b) for a radiocommunications transmitter or radiocommunications receiver operating under an apparatus licence, the frequencies outside the lower frequency limit and upper frequency limit specified in the licence.
section 145 determination means the Radiocommunications (Unacceptable Levels of Interference – 2.5 GHz Mid-band Gap) Determination 2012.
spectrum space means a three dimensional space consisting of a frequency band and a geographic area.
unwanted signal means all emissions from any radiocommunications transmitter which is not communicating with the radiocommunications receiver of a service protected by these guidelines.
wanted signal means the radiofrequency emission from a radiocommunications transmitter designed for communication between the transmitter and the radiocommunications receiver of a service protected by these guidelines.
wideband unwanted signal means an emission spread across a bandwidth greater than 4 MHz with 99% of its power contained within a bandwidth of 5 MHz.
(2) In these guidelines, unless otherwise specified, the range of numbers that identifies a frequency band includes the higher, but not the lower, number.
(3) The following terms have the same meaning as in the section 145 determination:
(a) centre frequency;
(b) device boundary;
(c) device boundary criterion;
(d) effective antenna height;
(e) fixed receiver;
(f) fixed transmitter;
(g) geographic area.
Note A number of terms used in these guidelines are defined in the Act and have the meanings given to them in the Act, including:
· ACMA
· apparatus licence
· class licence
· frequency band
· interference
· radiocommunications receiver
· radiocommunications transmitter
· Register
· spectrum licence.
Part 2 Background
2.1 Interference
Interference occurring between adjacent spectrum licences consists of:
(a) in‑band interference, across the geographic boundaries; and
(b) out‑of‑band interference, across the frequency boundaries.
2.2 Interference management
(1) Interference is managed by creating emission buffer zones along the geographic and frequency boundaries of the licence, using a number of provisions of the Act, including:
(a) the core licence conditions that all spectrum licences are subject to (see section 66 of the Act), about:
(i) emission limits outside the geographic area; and
(ii) emission limits outside the frequency band; and
(b) the determinations made under subsection 145 (4) of the Act about what constitutes unacceptable levels of interference; and
(c) advisory guidelines made under section 262 of the Act, about managing interference in specific circumstances.
(2) These guidelines have been made to provide guidance on the management and settlement of interference to radiocommunications receivers operating under spectrum licences in the 2.5 GHz Mid-band Gap and caused by radiocommunications transmitters operated under other licences.
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Part 3 Managing interference from other services
3.1 In‑band interference
(1) In‑band interference caused in a radiocommunications receiver operating under a spectrum licence by a radiocommunications transmitter operating under an adjacent spectrum licence is managed by:
(a) the core conditions of the licence under section 66 of the Act; and
(b) the device boundary criteria under the section 145 determination.
(2) In‑band interference caused in a radiocommunications receiver operating under a spectrum licence by a radiocommunications transmitter operating under an apparatus licence that is issued after the commencement date of the Radiocommunications Spectrum Conversion Plan (2.5 GHz Mid-band Gap) 2012 is managed as if the transmitter is operated under a spectrum licence.
(3) The same device boundary criteria that apply to spectrum licensed radiocommunications transmitters also apply to radiocommunications transmitters operating under apparatus licences issued after the commencement of the Radiocommunications Spectrum Conversion Plan (2.5 GHz Mid-band Gap) 2012. Therefore, spectrum licences are afforded the same level of in‑band protection from new apparatus licensed radiocommunications transmitters as they are afforded from radiocommunications transmitters operated under adjacent spectrum licences.
(4) Application of the device boundary criteria manages in‑band interference and these criteria incorporate emission limits that provide reasonable protection throughout the total geographic area of a licence. Emission limits are also used to manage out‑of‑band interference but these do not provide protection along the frequency boundaries of a spectrum licence throughout the entire geographic area. Because of the nature of out‑of‑band interference, emission limits cannot be used to provide protection from out‑of‑band interference for radiocommunications devices that are located near each other, for example, at multi‑operator sites.
(5) The ACMA will not regard in‑band interference to a radiocommunications receiver operating under a spectrum licence caused by a radiocommunications transmitter operating under a class licence as unacceptable if the operation of the transmitter complies with all relevant conditions of the class licence.
Note Spectrum licensees must accept any interference caused by apparatus licensed transmitters whose licences were issued before the commencement date of the Radiocommunications Spectrum Conversion Plan (2.5 GHz Mid-band Gap) 2012.
3.2 Out‑of‑band interference
(1) Out‑of‑band interference is difficult to predict because the levels and frequencies of unwanted emissions depend on both the proximity and the operating frequencies of radiocommunications transmitters and radiocommunications receivers. In addition, out‑of‑band interference:
(a) can extend for many megahertz either side of the frequency boundary of a spectrum licence;
(b) is dependent on the quality of the radiocommunications receiver as well as the levels of radiocommunications transmitter emission; and
(c) is difficult to accurately model.
(2) If emission limits were used to manage out‑of‑band interference for radiocommunications 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 spectrum licence extend throughout the entire geographic area of the licence.
(3) Therefore, emission limits that manage out‑of‑band interference throughout the entire geographic area of a spectrum licence (including communal sites) cannot be used because they would lead to a loss of use of the spectrum on both sides of the frequency boundary.
(4) 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 radiocommunications receivers. A minimum level of receiver performance has to be specified in conjunction with the compatibility requirement because the performance level of receivers:
(a) affects the level of interference; and
(b) varies widely for receivers operating under spectrum licences.
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Part 4 Requirements for receiver protection
4.1 Recording radiocommunications receiver details in the Register
A radiocommunications receiver operated under a spectrum licence in the 2.5 GHz Mid-band Gap will not be afforded protection under these guidelines unless details of the receiver are included in the Register.
4.2 Mobile and nomadic devices
The compatibility requirement in Part 5 of these guidelines does not apply to mobile or nomadic radiocommunications receivers because the transient nature of their location prevents the use of this requirement as an interference management procedure. Mobile and nomadic radiocommunications receivers have by their nature the ability to avoid an interference source, unlike a fixed receiver.
4.3 Frequency band
A radiocommunications receiver operated under a spectrum licence in the 2.5 GHz Mid-band Gap will not be afforded protection for the reception of wanted signals outside the band 2575 MHz to 2615 MHz.
4.4 Notional receiver performance
(1) The level of interference caused by out‑of‑band emissions depends on the interference susceptibility of the radiocommunications receiver. Emission levels from radiocommunications transmitters should not have to be reduced below a point where the poor performance of the radiocommunications receiver is the main cause of the problem.
(2) It is necessary to establish a benchmark notional receiver performance level for the radiocommunications receiver when setting a compatibility requirement for radiocommunications receivers.
(3) The notional receiver performance level is set out in Schedule 1. A radiocommunications receiver must meet this level of performance to gain protection from interference caused by radiocommunications transmitters.
Note Schedule 1 specifies the anticipated receiver performance based on information available to the ACMA at the time of making these guidelines.
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Part 5 Compatibility requirement
5.1 Compatibility
(1) The performance of a fixed radiocommunications receiver operated under a spectrum licence in the 2.5 GHz Mid-band Gap meets the compatibility requirement if the receiver:
(a) has at least the notional level of receiver performance set out in Schedule 1; and
(b) meets the compatibility requirement of the minimum wanted signal level set out in section 5.2; and
(c) has its details included in the Register before the date that the radiocommunications transmitter with which compatibility is sought has its details recorded in the Register.
5.2 The minimum wanted signal level at the receiver
(1) For the purpose of assessing compatibility with other services, the performance of a fixed radiocommunications receiver operated under a spectrum licence in the 2.5 GHz Mid-band Gap is a minimum wanted signal level at the antenna connector of ‑104 dBm/MHz for 90% of the time in any 1 hour period.
(2) The minimum wanted signal level is inclusive of a 1 dB increase in the receiver noise floor. Logarithmic scaling should be used to find the appropriate level in alternative bandwidths.
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Schedule 1 Notional receiver performance level
(section 5.1)
The notional radiocommunications receiver minimum performance level relates to:
· selectivity;
· intermodulation immunity; and
· blocking.
The notional radiocommunications receiver minimum level of performance is a product of duplex filtering from the antenna to the receiver and the performance of the receiver equipment. The minimum performance requirement is the combined performance measured at the antenna connector.
In the case where the overall combined performance of duplex filtering and receiver equipment can be shown to be equal to or greater than the combination of the individual requirements specified below, the notional receiver minimum level of performance shall be considered as having been met.
Receiver performance reference points
The frequency offsets specified for the notional receiver performance are specified with respect to the frequency limits of the spectrum licence under which the radiocommunications receiver operates. All levels are referenced to the antenna connector. The wanted signal level used for testing purposes (if required) should be a level equivalent to the minimum wanted signal level of the compatibility requirement in section 5.1. The notional antenna for a fixed receiver has a maximum gain of 22 dBi, including feeder losses.
Receiver adjacent channel selectivity
The Adjacent Channel Selectivity or ACS can be expressed as either the ratio of the unwanted to wanted signal at a given frequency offset between the centre frequencies of the channels or as the unwanted signal power.
The minimum notional radiocommunications receiver ACS performance requirement shall be 43.5 dB, measured for a wideband unwanted signal operating between offsets of 0 and 5 MHz from the frequency band edge of the licence; and 80 dB, measured for a wideband unwanted signal operating at offsets greater than 5 MHz from the frequency edge of the licence under which the receiver operates.
Receiver Intermodulation response rejection
The minimum notional radiocommunications receiver intermodulation rejection performance requirement expressed as the minimum tolerable wideband unwanted signal level of the outer interfering signal with offset of 10 MHz or more is ‑22 dBm/MHz. The assumed inner unwanted signal is carrier wave signal of ‑52 dBm located at an offset of 7.5 MHz from the licence edge.
Receiver blocking
The minimum notional radiocommunications receiver blocking performance requirement, expressed as tolerance to a minimum unwanted signal level:
· within the band 2555‑2635 MHz, at frequency offsets greater than 10 MHz from the licence frequency limits, for a wideband unwanted signal, is a power spectral density of ‑22 dBm/MHz; and
· outside the band 2480 to 2590 MHz, for an unwanted signal, is a total mean power of ‑20 dBm.
Note The accuracy of measuring equipment, measurement procedure and any corrections to measurements necessary to take account of practical filter shape factors would normally be in accordance with good engineering practice.
