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8960 in Wireless Device Design News

Issue 4 Series 2

Real world inside

Improve time-to-market by stress-testing mobile phones

The unprecedented complexity and subtle inner-workings of today’s cellular mobile phones too often result in failures during field testing which result in expensive, defect-fix verification cycles. Service providers and equipment manufacturers would like nothing better than to reduce the number of these verification cycles. Unfortunately, conformance tests and other traditional methods of validating equipment are increasingly inadequate at predicting how a phone will work once it’s on the network and in a user’s hands.

Although problems can be identified during field interoperability testing (IOT), or "drive testing" at the time of product release, this approach is expensive and time-consuming. What’s really needed is a way to subject the phone to the rigors of real-world usage while the phone is still in the lab. The earlier a design flaw is identified, the less costly it will be to modify, and the sooner the product will pass IOT and get to market.

The Agilent N5970A Interactive Functional Test (IFT) software for the 8960 wireless communications test set provides just such needed capability. The IFT software simplifies and automates the interface of an 8960 running a UMTS lab application, enabling stress-testing of cellular mobile phones via interactive, realistic scenarios that emulate a real user’s experience. By exercising the phone as it carries out multiple and simultaneous "user-experience" operations, the software helps design and validation engineers uncover errors earlier in the development cycle. By resolving issues early, phones pass field acceptance tests with significantly fewer verification cycles, which are required for defects found downstream in the development cycle.

  Figure 1
  8960

Interactive functional test

The N5970A IFT software allows automated or manual testing of the activities available in the 8960 lab applications. In the figure above, these appear in the window at the left and include SMS to and from the phone, MMS to and from the phone, UDP upload and download, FTP download, application web browser, call processing, battery profile, and network impairments.

To provide a realistic user test the software can simultaneously run multiple activities such as call processing, FTP download, and SMS; go idle for a period of time; and then alter the RF power to the phone as would occur when a mobile user changes networks. Impairments such as AWGN and cell power fluctuations can be added, and tests can be run over varying periods of time. The IFT software’s user interface has the ability to execute and track these activities while monitoring the current drain in the battery, which is a major focus area due to the ever-increasing number services and activities the phone can be performing at any time. Any issues found during the testing of a phone with IFT software can be easily identified by using its analysis and troubleshooting tools including battery profile, data throughput monitor, activity logger, and wireless protocol advisor.

With the data derived from these powerful tools, engineers can determine how complex issues - whether hardware, software, or protocol related - affect the functionality of a phone design. This type of real user-experience test goes above and beyond testing against conformance specifications. With IFT software engineers can locate even seemingly trivial issues that can snowball into much bigger problems when not found until later in the development cycle. IFT catches problems in the critical early stages of the development cycle so engineers can feel more confident their product is ready for release - reducing bottlenecks at the validation testing stage.

Modes of operation

The N5970A IFT software has three modes of operation:

  • Interactive mode allows engineers to manually set up and execute activities with the IFT software’s easy-to-use controls. These test processes can be saved in the software’s script interface for automated testing.
  • Script development mode is used to automate the test processes defined in interactive mode using the IFT software’s built-in, easy to use VB.Net scripting tool. Scripts can run the gamut from the very simple to the very complex, and once a script has been saved to a file, it can be modified and enhanced at a later time to include other user-defined tasks. It also becomes available as a test step that can be combined with other scripts into a test plan.
  • Stress test mode allows engineers to create an automated test plan that runs any combination or ordering of the scripts they have saved. Set up and execution of the test plan can also be controlled via API commands over the TCP/IP interface for remote control of the IFT software from a remote PC and/or program. Also as part of the automation process, engineers can set up email notification of test plan status and results, which allows for a more convenient method of monitoring an automated test.

Phone control

An important feature of IFT software is its ability to provide easy phone control for situations in which the phone’s user interface has not yet been fully developed or is not part of the product design – as in the case of a wireless data card, or because it is simply faster to use automated control.

Additionally, by implementing the IFT software’s interface to the device under test as an open interface (that is, by keeping open that portion of the software code), Agilent allows engineers to add their own unique interfaces. This flexibility greatly simplifies their access to varied and complex commands.

Test system components

The components required for a basic test setup include a server PC, a workstation running the IFT software, an 8960 running the UMTS lab application, and a router to connect these components.  The phone under test is connected to the test set via RF. The server PC runs application servers (all of which are provided on a server installation disk that is part of the IFT software package) such as Filezilla for FTP transfers, NowSMS for SMS and MMS transfers, Apache for an http server, and an UDP server.  A power supply is required for battery profile analysis.

Ideal for design integration and validation labs

The IFT software makes the 8960 an even more valuable tool for developing mobile phones and devices. For design and integration engineers, this solution provides superior network emulation that fully exercises a phone’s call-processing functionality, induces impairments to create real-world scenarios, and measures the phone’s response to find and resolve issues earlier in the design cycle.

When used in the validation stage, the IFT software finds design issues that are missed by other stress testing methods, including conformance tests - and it finds these issues before phones are released to the service providers. Moreover, the IFT software/8960 solution is ideal for regression testing after a design fix has been made. With this one powerful solution, engineers can reduce both the number and duration of expensive verification cycles of a phone. That will be good news to service providers, who will also find the IFT software useful in performing acceptance tests.

For more information about the Agilent N5970A IFT software

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