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What is a Radio Risk Analysis?

Steve Hayes EMC Expert
By Engaged Expert Steve Hayes Product Qualification Testing

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The Radio Equipment Directive (RED) – 2014/53/EU was published as a replacement to the Radio & Telecom Terminal Equipment Directive (R&TTE) following a review process. This review modified the scope of the directive and aligned it with terminology and philosophy of the New Legislative Frame (NLF). When looking at Radio Risk Analysis, unlike many of the other directives that were modified as a consequence of the NLF, the RED does not specifically state that documentation shall include an adequate analysis of the risks when following Annex II. 

Additionally if Annex III is followed (i.e. EU-Type Examination) it requires that the "… technical documentation shall make it possible to assess the radio equipment's conformity with the applicable requirements of this Directive and shall include an adequate analysis and assessment of the risk(s)."

The European Commission subsequently clarified the position and issued a document* which confirms that, whilst not specifically mentioned for Annex II, there is a requirement for manufacturers to perform an analysis of the risks associated with radio equipment and compliance with the essential requirements.

Risk, however, has multiple meanings within the directive and corresponding NLF ranging from risks associated with the product (which is the responsibility of the manufacturer); products that present a risk which is the responsibility of the market enforcement agencies and actions required by actors in the supply chain where risks have been identified.

Radio Risk Analysis - What does ‘Risk’ mean in the context of the RED?
  • The RED mandates that manufacturers consider the following essential requirements:Article 3.1(a) - the protection of health and safety of persons and of domestic animals and the protection of property, including the objectives with respect to safety requirements set out in Directive 2014/35/EU, but with no voltage limit applying
  • Article 3.1(b) EMC – an adequate level of electromagnetic compatibility as set out in Directive 2014/30/EU
  • Article 3.2 - Radio equipment shall be so constructed that it both effectively uses and supports the efficient use of radio spectrum in order to avoid harmful interference

This document only considers risks associated with Article 3.2 as the other risks have been covered previously.

The fundamental objective of the directive is to have effective and efficient use of the RF spectrum for radio equipment (both transmitting and receiving) and to avoid harmful interference.

The directive specifically concentrates on the risk of harmful interference.  Clearly these risks are different dependant if the product is a transmitter or receiver and hence are separated out in this paper.

As the primary author of radio standards, ETSI consider the risks associated with radio equipment in their guide (ETSI EG 203 336 V1.1.1 Electromagnetic compatibility and Radio spectrum Matters (ERM); Guide for the selection of technical parameters for the production of Harmonized Standards covering article 3.1(b) and article 3.2 of Directive 2014/53/EU). This ETSI guidance is used in determining what tests radio equipment should be mandated for candidate standards published for citing on the OJEU.

There is a potential overlap between ‘harmful interference’ as defined by the RED and immunity from the electromagnetic spectrum as defined by the EMC Directive. This is explained in the following diagram, where all interference tests associated to the allocated frequency channel are covered by RED standards and those outside the allocated bands are subject to EMC tests.

Inbound Interference example

Transmitters

If any of the fundamental characteristics of a transmitter deviate to those defined for spectrum access there is a possibility of creating harmful interference. These fundamental characteristics are those that are defined by the ITU (or CEPT) and flowed down to organisations such as the Electronic Communications Committee (ECC) of CEPT, which ETSI use in turn for the parameters defined in standards (for e.g. RED). 

These standards however are based on the transmitter being used in a particular way or environment (for example, does the temperature extreme test adequately cover the actual temperature extremes of the application?).

Consequently the risk analysis of a transmitter is more about confirming that it will be used in a way that was envisaged by the standards makers and if not, documenting it and mitigating the risk by additional measures (extending the temperature extremes, for example). One of the most common parameters overlooked is the use of one radio transmitter used in close proximity to another and generating harmonically related new frequencies (intermodulation). ETSI Guide EG 203 367 Guide to the application of harmonized standards covering articles 3.1b and 3.2 of the Directive 2014/53/EU (RED) to multi-radio and combined radio and non-radio equipment takes this type of scenario into account and highlights the issues accordingly. Since this standard is not a published harmonized standard, it is often overlooked by manufacturers.

The following questions should be asked by manufacturers during the risk analysis phase of product realization:

  • Does the harmonized standard cover the operating environment of my equipment?
  • Is my transmitter co-located with another?
  • Will any of the parameters change if I install the transmitter in a different type of enclosure (temperature extremes, efficiency of the antenna/radiation etc.)
  • What will happen to the conformity of the product over time? Things to consider may include component or subassembly failure such as antenna matching networks, antenna connectors, or corrosion to grounding system such that the radio still transmits, but not with all aspects of the intended design
Receivers

Receiver characteristics have been specifically detailed within the RED and considered by standards bodies in the introduction of new harmonised standards. This is due to the fact that the RF spectrum is becoming more crowded and therefore the possibility of harmful interference is increasing.

Shared or adjacent channels on which the receiver is tuned are of particular concern since these aspects are most likely to cause a receiver not to be able to discriminate between the wanted and unwanted signal.

Similarly to transmitters ETSI have, and continue, to define receiver characteristics based on the interoperability and co-existence studies performed by others in relation to the type of service and sources of potential interference.  These requirements now form part of the normative requirements of ETSI Standards. Questions manufacturers should ask include:

  • Is the receiver being used in the way envisaged by the standard?
  • Has the receiver been assessed in the host such that its performance is consistent with actual use?
  • Have suitable technologies been employed such that spectrum sharing will not cause a lack of functionality? 
Conclusions

The Radio Equipment Directive provides a prescriptive set of characteristics for radio performance within harmonized standards that follow the essential requirements. Manufacturers need to ensure however that the corresponding tests defined with these harmonized standards adequately address the unique circumstances of an individual product. If there are any parameters of the radio equipment that are outside the scope of the harmonized standard, the manufacturer needs to mitigate these additional risks by performing additional assessments (tests). 

 

*Clarification in the RED guide - Risk assessment for module A - Ref: TCAM WG (10)04 Rev1 Risk assessment module A

 

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