Analytek - Mobile Phone Testing

Mobile battery testing software and services

Prolonging Life

Breathing new life into obsolete test equipment

As the march of mobile communications technology advances many companies within the industry find themselves with compliance testers which have simply become obsolete. The increasing importance of GPRS, EDGE and third generation technology has driven test and measurement equipment on to more and more sophisticated platforms with the result that older equipment is no longer suitable for compliance testing and no longer supported by the respective manufacturers.

Compliance testing at the leading edge is not the end of the story, however. There are many areas of testing to which older equipment can make an important contribution. Our customers have found that this relieves the workload on the up-to-date compliance testers which increases their availability to test leading edge functionality.

Analytek has targeted a number of areas with software for the older generation Rohde & Schwarz CRTP and CRTC instruments. It is no coincidence that the areas targeted require the greatest test time, resulting in the biggest payback in terms of increasing the availability of the new generation testers. In some cases, Analytek has enabled testing in areas which simply would not have been practical were it to be carried out on new generation testers.

 

Battery Performance Testing

Battery performance is an important characteristic by which mobile phones are rated and good battery performance can therefore set a mobile apart from its competitors. It is important for developers to be able to measure and track battery performance issues from the early stages of development since good battery management necessitates building-in efficient use of resources in both the hardware and firmware of the device. Testing battery life is by its nature a long-winded procedure. While some estimate of battery life can be obtained when a mobile is operated on a live network, the full picture can only be obtained when the mobile is operating under tightly controlled conditions over long periods of time.

The Analytek battery performance tester utilises a Rohde & Schwarz CRTC to provide a controlled network simulation for repeatable battery performance testing. The mobile is put through a preset regime of either a speech call (for "talk time" measurement) or an idle mode simulation with periodic location updates and SMS transfers (for "standby time" measurement). The test is designed to be compliant with the GSM Association / ECTEL "Battery Life Measurement Technique" however, all configuration parameters likely to affect battery consumption can be tuned by the user to customise the test.

The mobile is simply connected to the tester with a fully charged battery and the test is started. The test software determines the time taken for the battery to become exhausted and also makes measurements of the mobile's RF performance in order to determine if the mobile's performance degraded before it declared an exhausted battery. Once an event has occurred indicating an exhausted battery (for example an IMSI detach or dropped call) the total test time is recorded.

Regression Testing

Compliance testing in GSM generally only requires a device to complete each signalling procedure once. Furthermore, for most compliance tests, the device is only powered-up for a few minutes at a time. This contrasts sharply with the usage pattern of a device in the hands of a subscriber. Most mobiles remain powered-up continuously, making hundreds of calls and perhaps thousands of location updates before eventually being shut down, usually due to separation from a battery charger!

Mobile manufacturers need to satisfy themselves not only that their product meets the compliance criteria but that it will be reliable in the hands of the subscriber.

The Analytek Regression Tester is designed to put the mobile through an accelerated simulation of life in the hands of a subscriber. The software provides a stable network simulation, eliminating any problems caused by poor network coverage, and puts the mobile through a cycle involving thousands of calls, SMS transfers and other signalling procedures. Randomisation of key RF and signalling parameters can be applied to ensure good coverage of a broad range of conditions or the configuration can be kept static in order to concentrate purely on a known configuration. Statistics are kept regarding the number of failed signalling procedures during the testing.

The results of this testing can be used to ensure that acceptable reliability will be achieved in real life. As a profile of a product's reliability is built with continued regression testing, the metrics provided can be used to determine whether new firmware versions or the addition of new features have impacted reliability by comparison with results from previous builds. It can provide concrete facts where previously fears and doubts about a particular build of software may have caused unnecessary caution, or indeed at the other extreme where a change has impacted reliability but this has not been highlighted until a product is in the field.

The mobile communications industry spends heavily on field testing. Analytek do not believe that regression testing can replace all aspects of field testing but it seems only prudent to utilise otherwise idle test equipment to contribute in any way possible.

Receiver Quality Testing

Performance of a mobile platform in conditions of poor received signal quality is another area where Analytek have identified shortcomings in the conventional testing approach. At compliance the reference sensitivity tests consider the platform's BER performance during fixed signal and interferer conditions. However in reality, poor signal conditions change rapidly and the mobile's performance is just as dependant upon its ability to report signal conditions to the network accurately as its ability to remain in-call during periods of poor signal quality.

Analytek also have experience of "off-the-shelf" mobiles whose performance even above reference sensitivity is degraded to the point where a call cannot be maintained. Sometimes the degradation manifests itself in unexpected ways which would not have been identified during compliance testing, such as loss of synchronisation or failure to accurately report poor signal conditions. At other times, the problems are no doubt due to calibration and production tolerance issues which would not have been allowed to affect the "golden" mobile submitted for type approval.

The Analytek Receiver Quality test is designed to paint a very clear picture of a mobile's performance in conditions of poor signal quality. Primarily, it performs a graphical analysis of measured BER performance against RX quality reported by the mobile, as the serving cell signal is gradually reduced into the noise. This will immediately highlight inaccuracies in the rxqual reporting and give a measure of the stability of the device under poor signal quality. More than that, however, the Receiver Quality Test also simultaneously tracks the reported RX Level from the mobile and the timing accuracy of the mobiles transmitted signal. Where a mobile fails in poor signal quality conditions, the test arms the developer with much more information concerning the circumstances of the failure.

Note

While these applications have been designed to take advantage of an obsolete piece of test equipment, that is not to say that the user is obliged to use an obsolete user interface. All three applications run on a Microsoft Windows computer attached to the instrument using an ethernet interface and are modern programs taking full advantage of the power of the Windows platform.