In the January 2011 edition of the ECC Newsletter, we highlighted the importance of Short Range Devices (SRDs). Given their pervasive use in the European Community and the world over, short-range devices play a major and increasing role in the economy and in the daily lives of citizens, with different types of applications such as alarm and metering devices, radio frequency identification devices (RFID), local fixed and mobile communications equipment, e.g. door and car openers or medical implants. The development of applications based on short-range devices in the European Community also contributes to achieving specific Community policy goals, such as the completion of the internal market, promotion of innovation and research, and development of the information society.

So, SRDs are valuable applications which need a good regulatory environment to thrive. That requires keeping technical barriers low and simple, but also effective enough to avoid interference problems and the waste of spectrum. The ECC's Short Range Device Maintenance Group (SRD-MG) draws on the expertise of administrations and many industry partners, and has for years maintained its Recommendation ERC Rec.70-03, a de facto technical reference for SRDs in Europe and beyond, to keep it fully up-to-date with technology and user requirements and thus to keep the regulatory environment strong.

The EU framework and how the ECC works with it

The EU member states are also subject to the legally binding EC Decision on the technical harmonisation of spectrum used for SRDs¹. The ECC and the European Commission work closely together to keep this Decision and our Recommendation 70-03 current and mutually consistent. There is a permanent mandate from the Commission to the ECC's SRD-MG based on an annual review cycle and update of the technical annex of this Commission Decision. We are now on the fifth one.

A new report is being developed by the ECC in response to this permanent mandate. This report, CEPT Report 44, will be delivered in its first version expected to be approved for public consultation in September 2012. Another report, CEPT Report 43, was agreed by the ECC at its May 2012 meeting; that one deals specifically with a narrow SRD band at 169 MHz, and takes a similar philosophy to the one described here. In some ways it is a form of precursor to the approach of the 5th update cycle. Below we explore some of the current issues in this evolving sector, and set out some of the key principles which we expect to be used in CEPT Report 44.

What is changing?

This latest update sets out a clear policy background which marks a transition from the past and present situation where most applications are subject to quite specific conditions designed around how its existing equipment functions. This also comes with a salami-sliced set of narrow frequency bands each specific to a narrow range of applications.

The new objective is to increase flexibility for manufacturers and users by applying more generic technical conditions and reducing these to the minimum number necessary. This should bring two benefits. First, it may widen the technological approaches used to address a need (good for competitiveness) and, second, it should allow different applications to share the same ranges of spectrum, thus widening the ranges available to a given application; SRDs typically operate with quite a low usage density.

Of course this requires care. The new conditions need to anticipate what happens when dissimilar applications use the same spectrum in proximity, and proponents of some applications still make the case for quasi-exclusive spectrum, for safety reasons. Here we consider some of the implications of applying the principles of application and technology-neutrality in the European and national frequency regulatory frameworks.

CEPT Report 44: key points

The CEPT report should deal substantially with many of the issues covered in this article. In addition, within this update, CEPT proposes to add the existing regulations for meter reading, asset tracking and tracing and social alarms, taken from another EC Decision, 2005/928/EC. This follows the recommendations of CEPT Report 43. The existing regulation for wireless hearing aids should be included as for Adaptive Listening Devices (ALD). This will enable the separate EC Decision 2005/928/EC to be withdrawn. CEPT also proposes to add in the 169 MHz band a new regulation for non-specific SRD with Low Duty Cycle (LDC) parameters.

The rise of SRDs requires us all to take some positive steps forward. We're hoping to make some significant progress towards a predicable sharing environment and more generic technical conditions. Industry has an important role here too. By building SRDs in a way that minimises the risk of interference either from or to other radio communications services or devices, manufacturers can play their part in getting the devices working effectively without the need for regulatory intervention. This, together with a new range of flexible regulatory measures, will help to support the growth of this burgeoning environment enabling it to develop more confidently.

Background

The rest of this article deals in more depth with:

General neutrality principles

The EC framework for electronic communications services includes the principle that regulations should be application and technology neutral. This is intended to provide a more responsive environment for the continuous process of development and innovation in industry, by having regulations which can more easily admit new techniques and services. The scope of this EC framework includes the specific environment of SRDs (low power/general authorisation).

The technical layout of complete radio systems can be chosen with maximum freedom. The choice of modulation systems, error correction protocols and link establishment choices for robustness, latency and the application are all the choice of the manufacturer.

It is likely that for the same reason of technology neutrality there will be a trend towards grouping users not by application but more by the type of signal transmitted. This also supports the principle of 'commons' segments of spectrum not specifically designed for one application but available for those users obeying common access rules.

For example, access to a frequency sub-band will depend on a combination of parameters such as power, duty cycle, length of transmission, spectrum access method.

Application neutrality

Two characteristics of the SRDs sector are:

The term 'application' should not be misunderstood as a specific field of technology. However, the spectrum compatibility studies made when making spectrum regulations have to deal with real usage scenarios.

Even though the signal parameters may be identical, the relationship between spectrum access and perceived functionality is different for different applications. Therefore, true application neutrality can only be achieved if the proper technology, in terms of latency, reliability or data bandwidth is described for all application types in the same environment.

Another important element of achieving application neutrality is to recognise the responsibility of manufacturers to build short-range devices in a way that protects them against harmful interference to the best extent possible. This means minimising the risk of interference from other radio communications services as well as from other SRDs. This is particularly important for SRD uses which have high requirements in terms of latency, throughput, predictability or reliability of the wireless communications link for example. In such cases, the implementation of adaptive techniques to 'escape' interference or the definition of special conditions for certain frequency bands may provide a solution.

Technology neutrality

Technology neutrality has different definitions in different areas of technology and, in electronic communications, is usually described as follows: "the rules should neither require nor assume a particular technology." This definition centres on two important parts: "require" as in regulation and "assume" as in (harmonised) standards.

The main problem of technology neutrality is that it can detract from technical efficiency in spectrum use. It should still be possible to frame regulations so that, for instance, either analogue or digital modulation is allowed or a range of bandwidths is possible. In most cases, however, it is necessary to set specific technical conditions to allow successful and efficient sharing. Therefore, there may be a case for a special (very neutral) 'sandpit' area, akin to the concept of bands identified for industrial, scientific and medical applications (ISM), where technology neutrality is applied as far as possible, to assist the emergence of new technologies.

Technology neutrality is a desirable aim but, similarly, it is only truly achievable when applications have equal access and equal requirements.

In order to ensure that SRDs have equal access to bands they have to protect each other, instead of being directly protected by regulators. The regulators make the sharing rules mandated in spectrum regulation which then become the level playing field on which SRDs would have to operate and co-exist. This Predictable Sharing Environment (PSE) is understood as common behaviour for communication equipment and systems, common rules with common well-defined technical parameters and mitigation techniques to provide better defined sharing conditions within a specified frequency band.

From the requirements presented by industry, it is clear that some new services and functions, such as safety related applications, may require a more predictable sharing environment than that provided by traditional mitigation techniques. Different scenarios need to be considered during compatibility studies in order to determine an acceptable solution for combining services in the same frequency sub-band. We hope that by careful specification of the technical parameters and mitigation techniques, it may be possible to create a predictable sharing environment for the whole band that could apply to all SRDs.

Some practical regulatory steps

In practical terms, an important improvement is needed to achieve predictability of spectrum availability for some applications having specific requirements such as low latency, high reliability/availability or wideband data throughput. This requires a medium access definition for adaptive equipment. The relevant ECC and ETSI groups are giving attention to the presently under-developed dynamic spectrum access regulations. Existing techniques also need to be better evaluated, such as DAA (a more sophisticated LBT - Listen-Before-Talk), LDC (Low Duty Cycle) robust spread spectrum techniques or signal parameter requirements. The application of a MUF (Medium Utilisation Factor) may be used to make spectrum more application neutral. This is not a new concept. It is mentioned in ITU Recommendation SM.1046-2 and ETSI TG11 used the concept to devise the mitigation methods in standard ETSI EN 300 328. Ongoing studies in ECC and ETSI show that the principle cannot be applied without caution and setting boundary conditions for each frequency range.

Thomas Weber, ECO Expert and
Chairman, ECC Short Range Device Maintenance Group