Microwave Journal

Wireless Test Sets for 4G and Beyond

March 14, 2014

Wireless Test sets for 4G and beyond

An incredible amount of technology is packed into every smartphone and tablet. The list is long and getting longer: new and legacy cellular formats, multiple wireless-connectivity links, GPS capabilities, cameras, music players, Web browsers, and on and on. Putting all this power into the hands of several billion subscribers is overloading the frequency spectrum available within today’s wireless infrastructure. In response, the latest cellular standards include techniques such as multiple-input/multiple-output (MIMO) and carrier aggregation (CA). The goal of these advanced techniques is to help operators squeeze more capacity and higher data rates from their existing frequency spectrum.

Looking upstream to the industry’s product lifecycle, this environment also presents challenges to those who develop and manufacture the latest chipsets and user equipment (UE). Testing becomes more difficult when it comes time to characterize the performance of transmitters and receivers or check the behavior of an assembled device. Test engineers often turn to a category of instruments known colloquially as “one-box testers” and more formally as “wireless test sets.” These solution-specific instruments simplify the process of checking the performance and behavior of chipsets and UEs. Similar to the devices they test, these instruments are becoming increasingly integrated: many include sources for receiver testing, analyzers for transmitter testing, standards-compliant measurements, and a host of built-in functions to support manual, sequenced and automated testing. This one-box approach has proven to be more convenient and time-efficient than the chore of patching together individual instruments and perhaps a PC. Because these testers are often easily upgradable, they are also cost-effective over the long run.

Today’s increasingly complex chipsets and UEs require a new generation of instruments designed to meet present needs and provide extensibility to satisfy future requirements. Following in the footsteps of the 8960, Agilent has recently introduced two new additions to  its industry-leading family of testers: the E7515A UXM wireless test set and the E6640A EXM wireless test set.

Figure 1

Figure 1 Users can evolve as technology changes with Agilent UXM's extensible architecture.

R&D: Gaining Clarity at Crucial Handoffs

Design and validation are essential stages of the R&D process. At key handoff points, engineers make judgment calls about every design, deciding if a chipset or UE is ready to clear the crucial hurdles imposed by internal specifications, conformance tests and operator requirements. Testing covers areas such as functional behavior and RF performance. Clarity around each decision comes from accumulated insights about standards, technologies, in-house design practices, and more.

Defining an Architecture for Today and Tomorrow

The Agilent E7515A UXM wireless test set is the most highly integrated signaling test set created for functional and RF design validation in the 4G era and beyond. It provides a wealth of capabilities that enable testing of the newest designs, delivering LTE-Advanced category 6 now and handling increasingly complex requirements in the future.

The foundation of these “now and later” capabilities is an extensible architecture that can evolve as technology changes: the UXM includes upgradable processors, multiple expansion slots and high-speed interconnects (see Figure 1). Through its industry-leading combination of two independent 100 MHz RF transceivers, the UXM enables multiple cells, carrier aggregation, MIMO up to 4×2 and integrated fading. The instrument also provides built-in servers for extensive functional test applications. Building on that, the UXM is a future-ready, multi-format-capable platform that will handle the next advances in antenna techniques, component carriers and data rates.

The net effect: the UXM enables test engineers to ensure that LTE/LTE-A devices can sustain maximum category 4/6 rates and handle realistic fading and MIMO scenarios. As a result, engineers can wring out every design with integrated fading, flexible receiver testing and trusted transmitter measurements—and the UXM is poised to handle more complex test applications in the future.

With its wealth of integrated capabilities, the UXM lets engineers dive more deeply into functional testing by emulating a wide range of complex operations. For example, with two independent cells built in, the UXM makes it possible to check LTE handover behavior with just one instrument. Connecting a UXM to an Agilent 8960 wireless test set supports verification of the increasing number of inter-radio access technology (IRAT) handover scenarios. The inclusion of Wireshark-based logging software enables thorough analysis of protocol messaging.

Figure 2

Figure 2 Agilent X-Series measurement applications can be used with the UXM wireless test set.

The UXM also ensures greater confidence in RF performance with flexible automated testing and industry-proven Agilent X-Series measurement science (see Figure 2). One key area of testing is the full range of 3GPP channel configurations. The UXM provides integrated capabilities and flexible automation software with Agilent’s Wireless Test Manager (WTM), making it easy to efficiently step through the full range of 3GPP channel configurations for a device-under-test.

To support the development process from early designs to finished products, the UXM supports signaling and non-signaling (i.e., test mode) operation. This lets engineers focus on characterization of RF performance: the UXM pushes aside the protocol barriers and enables the engineer to “just connect” to the device under test.

Manufacturing: Solving Today, Evolving Tomorrow

In the wireless industry, successful manufacturing organizations need tools that help them meet ever-tougher goals and tighter schedules. In addition, access to the best resources will help them deal with the technical, business and operational risks that, when managed carefully, ensure success. When these factors are under control, the organization is able to achieve several key goals: ramping up quickly; achieving and optimizing volume production; minimizing the total cost of test; meeting budget; and reducing wastage.

The measurement challenges generated by today’s multi-format, multi-band devices are difficult—and the key to success is finding test methods that are more efficient and more effective. Within this context, the Agilent E6640A EXM wireless test set builds on the non-signaling and sequencing capabilities of Agilent’s previous test sets. In addition, the EXM provides a new architecture that expands parallel testing and provides scalability to match changing production needs. To support the fastest testing of the newest chipsets, the EXM is in sync with the latest cellular and WLAN chipsets. It delivers the speed, accuracy and port density needed to ramp up rapidly and optimize full-volume manufacturing of a broad range of multi-format devices, including those that use LTE-Advanced carrier aggregation, 802.11ac WLAN MIMO, and more.

In the new product introduction (NPI) stage, the EXM provides certainty through chipset compatibility and validated test capabilities that directly control chipset functionality. This includes the fastest, most reliable calibration and verification functions offered in each vendor’s chipset. The EXM’s broad multi-format, multi-port flexibility handles today’s complex chipsets while allowing easy upgradability for tomorrow’s features. For greater scalability, the EXM can be configured with up to four independent transmit/receive (TRX) channels, each of which is a complete vector signal generator, vector signal analyzer and RF I/O section. To further extend port density, the EXM can be customized to connect up to 32 DUTs through multi-port adapter (MPA) technology.

The EXM enables manufacturers to easily keep pace with production capability and capacity needs. In addition to its multi-port and multi-format capabilities, the EXM helps maximize throughput and yield with fast and accurate parallel testing of multiple devices. This comes from the ultra-fast data processing and transfers, advanced sequencing and single-acquisition/multi-measurement (SAMM) capability built into the EXM. The flexibility of the EXM preserves initial equipment investments by making it easy to evolve with changing production needs. Each unit can be expanded with up to four TRX modules, and these can be upgraded with higher frequency coverage and wider analysis bandwidth.

For maximum reliability and uptime, the EXM has been tested to survive the rigors of the factory floor. When calibration or repair service is needed, Agilent’s global presence ensures fast turnaround times. The EXM is designed, built and supported to ensure success in manufacturing.

The drive for faster data speeds and compelling new services seems likely to continue without end. So does the trend toward ever-denser integration of new capabilities into user devices. To help developers and manufacturers keep pace, Agilent has created two highly integrated wireless test sets—the UXM and EXM—that offer the flexibility and extensibility enabled by modern, modular architectures. Both platforms provide the future-readiness needed to meet present and future requirements, and both offer the investment protection that comes from a platform that is easily reusable and upgradable.

New-generation test hardware offers tremendous benefits, but there’s more to the story. Agilent also offers access to a broader set of resources—application engineers, manufacturing test integration teams, worldwide support, and more—that can help developers and manufacturers handle the unknown, stay on track and meet their goals for the newest chipsets and UE.

Agilent Technologies,
Santa Clara, CA,