Using Correlated Test Results to Improve Wi-Fi Product Design, Part I
The evolution of WLANS has resulted in a steady stream of new technologies and products. Wireless system designers are well aware that the complex wireless environment — with its myriad of variables such as RF, interference and multi-path reflections — can impact the success or failure for new products.
By Azimuth Systems
Wi-Fi test methods have lagged behind the evolution of Wi-Fi products. As such, system designers have often resorted to developing "homegrown" solutions that are principally point-to-point tests. Such test beds often use isolated screen rooms that control RF interference or large open spaces for tests that contemplate motion — like rate versus range.
As wireless environments become more complex and customers demand more from their Wi-Fi products, manufacturers have begun to employ standardized test methodologies that provide a more accurate system-level view. The new generation of Wi-Fi test equipment not only enables greater RF control using a cabled environment, but also allows the user to regulate every aspect of the system under test — including environmental factors and load conditions. Today's Wi-Fi test solutions provide what previous homegrown solutions could not: repeatable outcomes, system scalability and test automation. Addressing these fundamental needs of wireless designers will enable the continued rapid growth of WLAN technology in the home, small business and enterprise.
Addressing Emerging Issues
How will Wi-Fi testing equipment continue to evolve as the industry turns to emerging wireless applications, such as dual-mode (Wi-Fi/cellular) phones, video-over-Wi-Fi and 802.11 mesh networks? These applications increase the complexity of developing, implementing and managing new Wi-Fi enabled products, highlighting an even greater need for comprehensive, repeatable and verifiable Wi-Fi testing. To maintain their competitive edge, wireless-device manufacturers require test methodologies that improve product quality and speed time-to-market.
This article is the first in a series that will discuss trends in wireless testing. This segment will briefly review the issues associated with testing wireless products and applications in an increasingly complex Wi-Fi environment. It will also detail the benefits of adopting a cross-functional, integrated approach to wireless testing, including improvements to test reporting, test scheduling and equipment inventory and backup. In the second and third installments, the discussion will include the concept of channel emulation to test multi-path signals in a controlled environment and the emergence of 802.11n-based MIMO technology.
Controlled-RF Testing Enables Correlated Test Results
Wireless designers face challenges that are not contemplated by their counterparts who develop wired networking products. "Real-world" wireless performance issues, such as end-user throughput and roaming times, are affected by a number of factors, including motion, interference, unpredictable traffic loads and interoperability of multiple-vendor network components. These factors make it difficult to emulate the conditions of wireless networks in a repeatable, scalable and automated manner.
Today's wireless testing systems are designed to solve these problems by emulating real-world conditions in a controlled laboratory environment. Many wireless manufacturers are now using turnkey systems to configure an entire Wi-Fi network in a bench-top framework that provides complete RF isolation and control. This allows them to easily simulate and evaluate Wi-Fi equipment under varying mobility conditions and traffic patterns, and precisely analyze the results.
Another significant difference between wired and wireless testing is workflow and data correlation. In the "wired world," test engineers — regardless of functional department — can map, store and correlate testing data across the product-development life cycle. Adopting a similarly integrated and cross-functional approach to wireless testing will provide wireless equipment manufacturers, service providers and end-users with major operational benefits.
For that reason, leading Wi-Fi test vendors have designed solutions that can be used throughout the product-development cycle. Since Wi-Fi products undergo testing at various stages — including hardware and software design, product development, quality assurance and marketing — multiple engineering groups within a single organization can take advantage of the same test equipment and methodologies. In addition to maximizing a company's investment in test equipment, cross-functional testing has real benefits to product quality and time-to-market. By using the same test equipment across an organization, disparate engineering groups can collect and share data and correlate results across geographies and over time.
Correlated Test Results Enhance the Product Development Cycle
A cross-functional approach to wireless testing integrates controlled-RF systems with SQL database software and an HTML interface, providing greater visibility into the performance and interoperability of wireless infrastructure equipment and clients. Developers of wireline networks have taken advantage of similar products for many years, so the tools and processes should be familiar to most engineers.
In a typical wireless testing environment, each engineering group manages its own controlled-RF testing platform using a central console. By integrating an SQL database to multiple consoles, an organization can automatically collect and interpret data across functional groups, providing greater insight into specific product challenges. For example, surprising roaming-algorithm results discovered during quality assurance testing can be correlated to earlier test results run during software development. Separate engineering groups can also share customized test scripts to build a comprehensive, repeatable and verifiable Wi-Fi testing methodology that is unique to their company, improving quality and ensuring quick time-to-market.
An integrated SQL database has three operations:
- Test Reporting— An SQL database automatically collects test results from the central console in each testing department and imports them into a central database. There, users can view the product's performance and interoperability results across the entire organization. They can also compare multiple test run results for the easy assessment of historical and new results
- Test Scheduling— An SQL database provides a single site-wide interface to schedule and automate specific tests, ensuring that the correct scripts are loaded, licensed and run according to pre-defined times and frequency. An integrated scheduler provides a central control to monitor availability, progress and execution results, maintaining a history of tests run
- Equipment Inventory and Backup— An SQL database maintains a record of the hardware and software specifications of each test console to allow scheduling and test run validation, in addition to central cataloging and reloading of back-ups
- In the next series, these operations will be further integrated into the global process of developing evolving real-time Wi-Fi test systems
Conclusion
The controlled-RF testing platforms have rendered the homegrown testing solutions of the past obsolete, revolutionizing the testing industry in the process. But Wi-Fi testing equipment must continue to keep pace as Wi-Fi products and technologies evolve.
Because multiple engineering groups across an organization have adopted controlled-RF testing platforms, it is critical for them to review results quickly and compare them to those of their colleagues. A cross-functional approach to wireless testing marries controlled-RF platforms with SQL databases. This allows an organization to automatically correlate data across functional groups, such as design, development and quality assurance, to provide greater insight into specific product challenges. The end result is improved Wi-Fi testing that increases product quality and speeds time-to-market.
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