GSM Conformance Testing

By Stuart Graves, Senior Engineer, Samsung EURO QA Laboratory

Testing GSM handsets to meet the regulatory and market requirements can be a complicated affair. Although mobile phones have been with us for some time now, they are still continuing to develop additional features and modes of operation. Major new features being developed at the moment include GPRS and the much written about 3G. With standard handset sales now stabilizing after a huge upsurge for demand in previous years, 3G is being seen as key to the continuing success of mobile Telecommunications technology. It is important therefore that the progression from design to market acceptance is as smooth as possible. This will to some extent depend on the testing standards and the test platforms gaining stability as soon as possible.

The European Telecommunications Standards Institute (ETSI) develops the specifications for the new features via a Partnership Project (3GPP). Designing a product to a continually changing set of core specifications would be impossible, so a number of parallel specifications are released, each a progression in terms of features from the last. The manufacturer then designs his product to meet any one of these releases. Once the phone has been designed and built then it’s time for conformance testing. Tests can be broken down into that which is required for regulatory purposes and those driven by market forces, although there will obviously be a considerable amount of overlap.

Regulatory

In Europe the rules governing the regulatory requirements of mobiles phones are laid down within the R&TTE Directive. This has been in force since 8^th April 2000 and replaces the more stringent TTE Directive. The directive lists the essential requirements for a mobile phone and detail Safety, Specific Absorption Rate (SAR), Electromagnetic Compatibility (EMC) and Spectrum Usage as areas covered. There is also, contained in Article 3.3 a list of requirements that the Commission can decide to apply at a later date and these include the ability of the handset to interwork with the Network. The Official Journal provides a list of Harmonised Standards with which to test against to meet the directive. There are harmonised standards for EMC, Safety and SAR. Spectrum usage is covered in EN 301 419-1 and EN 301 511. These two standards provide a list of tests that should be passed to satisfy article 3.2 of the directive. The R&TTE whilst mentioning network interoperability does not currently require it and so there is a market requirement to ensure that when placed on the Network a phone will work the way it is designed to and not do harm or use valuable resources incorrectly. With the exception of America this is covered by a voluntary scheme called the GSM Certification Forum (GCF).

GCF

The GSM Certification Forum (GCF) is comprised of operators, manufacturers and test houses from around the world and was formed with the objective of establishing an independent programme to ensure global interoperability of GSM terminals. The GCF testing regime covers all aspects of interoperability including RF, Protocol, SIM as well as Field trails. Laboratory testing of handsets is actually performed on a small number of test platforms running hundreds of test scripts. It is the GCF’s role to ensure that there is traceability in this process. The test equipment manufacturers have to take the test, as defined by the test specification and write a script to run on their test platform. It is essential that one test equipment manufacturer does not interpret this differently from another else you may get the situation, heaven forbid, where one handset passes a test on one platform but not another. To ensure this is not the case a means of validating the tests/platforms has been devised and improved on over the years. Due to the fact that there are a lot more tests required by the GCF than for regulatory purposes it is essential that this process be kept under close control. With the introduction of 3G this task has now become harder. There are more tests on more platforms and both are continually changing to reflect the speed at which new features are introduced.

Future

A key contributor to the worldwide success of GSM has been the efforts made by the operators, manufacturers and test houses to develop a harmonised approach to testing. It has meant that all handsets have undergone a similar if not identical test regime, giving a confidence to customers that a handset will interwork with any network. This co-operation, carried out amongst various groups and committees must continue for 3G to enter the market place as smoothly. It is therefore essential that whilst commercial pressures dictate getting new featured handsets to market quickly, the basic framework of cooperation set up for GSM continues to function.

Stuart can be contacted on +44 (0)1252 863800 or email sgraves@samsung.co.kr.