Test solutions for 3G mobile phones

Mobile phone technology is shifting from 2G/2.5G to 3G. The next generation of mobile phones will integrate multiple functions such as voice, data and images. The content to be tested is closely related to protocols, networks, channels, interoperability, etc., and mobile phone test cases are needed to conduct complete tests. At present, reducing the cost of testing and shortening the testing time are still challenges faced by mobile phone test engineers. The introduction of 3G mobile phone test solutions will help (Chinese) test engineers understand the development of 3G mobile phone testing and its supporting solutions.

At present, with the development of integrated circuit technology and broadband technology, the mobile phone industry is shifting from 2G/2.5G represented by GSM, CDMA, PCS and GPRS to 3G based on wireless network broadband technology, integrating voice, data and video images. Driven by the strong development of mobile broadband application businesses such as mobile commerce, global positioning services, mobile electronic payment, mobile medical care, etc., it is expected that mobile phones with 3G functions will start mass production from 2004, and the mass production scale will exceed one million units in 2005.

As the integration of mobile phone chips becomes higher and higher, mobile phones are developing in the direction of smaller modules and more functions, while the price is showing a downward trend. On the one hand, the 3G mobile phones have many functions, which puts higher requirements on the mobile phone testing industry. Table 1 lists the main test items for 3G mobile phones. On the other hand, the testing industry has to face the increasingly severe demand for reducing testing costs.

Generally speaking, people choose and evaluate mobile phone test equipment mainly from the aspects of test time, floor space and equipment cost. However, now we have to consider: in order to meet the test requirements of 3G mobile phone testing for multiple functions, we should consider how to integrate and configure a set of test systems to meet the requirements of the entire assembly line from the beginning to the end of the production line for test equipment, how to select test tool software and standard libraries to meet the needs of future development, and so on.

At present, flexible configuration is the general requirement that test engineers put forward to test equipment providers, that is, a configuration platform for instrument systems is needed so that a set of test equipment can not only complete complex 3G mobile phone production tests, but also can be flexibly configured with independent test equipment with standard instrument bus interfaces to complete complex design test tasks. At present, around the three points of shortening test time, reducing test equipment costs and improving configuration flexibility, the solutions provided by test equipment suppliers show the following diversified development trends.

Provide powerful comprehensive tester

Develop a universal, upgradeable, configurable, and 2G mobile phone compatible wireless communication protocol integrated tester to make it a mobile phone multi-protocol test set with strong upgradeability. Such an integrated communication test instrument integrates traditional box-type measuring instruments such as RF generators, spectrum analyzers, and power meters, and is configured with various options. It can complete a series of RF test tasks and allow equipment owners to extend the service life of the test equipment and have greater flexibility, meeting the transition from 2G to 3G testing and the needs of next-generation mobile phones for test equipment.

R&S's CMU200 is such a device. Based on such a universal test platform, you can purchase corresponding options as needed to configure it into test equipment that meets the requirements of GSM, IS-95, IS-136, AMPS, Bluetooth, UMTS and W-CDMA standards. In addition, Agilent's TS-5550 is also a similar comprehensive test equipment, which supports functional testing, RF testing, audio, battery and charging circuit testing, etc.

For users, this solution mainly involves large equipment investment, with each integrated tester costing tens of thousands of dollars. In order to recover the equipment investment as quickly as possible, this type of equipment usually has a parallel testing function, which can complete the testing of multiple mobile phones at the same time, as shown in Figure 1. Its main advantage is that it shortens the configuration and software configuration time of the test equipment, and the highly professional work such as test equipment configuration has been completed by the test equipment provider, thereby greatly shortening the user's testing time. However, since the mobile phone must wait for the assembly to be completed before testing, it is impossible to use this kind of expensive test equipment to eliminate problems in time during the production process. Even if it can be done, the testing cost is relatively high. In addition, this type of solution has many supporting options, and the support of the test equipment supplier is also needed in equipment selection.

Constructing an online test environment based on PXI bus

In order to further speed up the testing speed, the testing solution providers have proposed a mobile phone testing solution that takes the entire design test and production test into consideration. The starting point is to calibrate the test equipment configured in the entire production line to achieve a unified level of accuracy, thereby ensuring that the design test, functional test, repair station and sample quality test have a unified test standard, and saving equipment calibration time and instrument maintenance costs. Due to the use of consistent test methods and programmable operations, and the realization of flexible equipment configuration, it can also shorten the test time and save equipment investment.

By considering the test points on the production line in a unified way, the mobile phone can be tested in parallel. For example, the receiver and transmitter can be tested at the same time without waiting for the signaling and bit error rate tests to be completed before testing, which can greatly speed up the testing process. In addition, by planning the entire production line as a large test environment, problems found at subsequent workstations can be reworked in a timely manner, without having to calibrate the test equipment to a unified standard when problems are found.

The entire test line can be connected through the network to build an intelligent test platform, which can store, analyze and generate statistical reports of measurement data and timely grasp the quality dynamics of products on the production line. In addition to the use of mature Internet technology, PXI bus has played an important role in building test lines.

It is reported that the average cost of testing a mobile phone is about $1 and it takes about 1-3 minutes. Therefore, reducing the testing cost is still one of the focuses of OEM and EMS phone manufacturers. Although box-type measuring instruments are equipped with a large number of options, rich software packages, and professional personnel support for equipment configuration, the testing cost is still too high for many test equipment users. Test instruments based on the PXI bus provide a solution for these users.

Similar to the integrated tester solution, the PXI bus-based test platform must be equipped with a PXI-5660 RF signal analyzer and signal generator with sufficient real-time bandwidth, stable time base and vector test capability. The remaining test instrument functions are mainly realized through DAQ cards, thus forming a complete test platform. The DAQ card solution is particularly suitable for users who are very sensitive to test time and investment.

The test function is implemented by equipping NI with LabVIEW-based wireless test toolset, and can be used in conjunction with the TestStand test executive tool to further improve the efficiency of production testing. With such a test system, two old box-type test instruments can be replaced at the test station of the mobile phone production line, thus doubling the test throughput [3]. Since virtual instruments have great flexibility, the test environment can be configured and programmed independently, and more test problems encountered in the development and production processes can be solved by using the test tools provided by third-party developers of the Virtual Instrument Alliance.

The biggest benefit of using virtual instruments based on the PXI bus is that you can choose more modular and upgradeable test devices, avoid the investment risks brought by purchasing box-type measuring instruments, and continuously upgrade and expand modular test devices according to changes or increases and decreases in standards and test objects.

At present, in order to meet the requirements of the 3G market for test solutions, test solution providers have been competing in protocol testing, interoperability testing, network infrastructure testing, channel testing, base station testing and 3G test cases. 3G system performance testing and optimization are the focus of the industry. The CDMA Test Forum (www.cdg.org) and the UMTS Forum (www.umts-forum.org) bring together leading 3G test solution providers, such as Agilent Technologies, Anristu Wireless Solutions, Comarco Wireless Technologies, Ericsson, Lucent Technologies, Nokia, Racial Instruments, Rohde & Schwarz, Spirent Communications, Sprint and Verizon Wireless.

The 3G market has huge opportunities. International cooperation on how to provide 3G test solutions is becoming increasingly close. Leading operators, mobile phone solution providers, and test solution providers are gradually improving 3G test solutions through intellectual property licensing, establishing cooperation agreements, and authorizing each other to sell test supporting solutions, as shown in Table 2.

Conclusion

The difficulties faced by the 3G testing field at present are mainly due to the large number of test objects, complex test content and levels. It is difficult for one or two companies to dominate the world. To provide a package of 3G test solutions, global cooperation is necessary. Development and cooperation have become the mainstream of 3G development. Many test solution providers mainly exchange information with each other through various forums and exhibitions. Through strong cooperation, the development of 3G test solutions is launched. Since 3G test solutions are very complex and equipment investment is large, 3G test outsourcing will be the main solution to meet the challenges of 3G testing in the future. With the improvement of manufacturing technology, the reliability of each component of electronic products has also been greatly improved, so the necessity of testing each component has been greatly reduced. As long as the spot check method is adopted, the cost of mobile phone testing can be further reduced and the test time can be shortened.

References

1. Agilent's TS-5550 Cellular Phone Functional Test Platform, Agilent

2. Comprehensive Manufacturing Test System, Willtek

3. Mobile Phone Online Test Application, National Instruments

4. Library simulates 3GPP mobile phone test cases, Anristu

5. www.google.com

6. www.cdg.org

7. www.umts-forum.org

Author: Zhou Zhiyong

Email: simonzhou@eetchina.com