LabVIEW and PXI Drive Next-Generation Wireless Test
Print
How many wireless devices do you use every day?
Think for a moment about the IEEE 802.11a/b/g transceiver providing Wi-Fi on your laptop. You also might have a 315 MHz FSK transmitter that remotely unlocks your car doors. A 433 MHz ASK transmitter probably provides wireless remote access to your garage door. Your car might use satellite radio, a GPS navigation device, or even an RFID tag at the toll booth. RF technology is everywhere, and all signs point to the integration of even more wireless devices in the future.
This explosion of wireless adoption produces new challenges for designing and testing products with an RF component. National Instruments is helping you meet these challenges with a suite of new tools optimized for wireless test (see Figure 1). Explore the following three trends in the wireless industry that require a new approach to wireless device test.
Figure 1. You can implement wireless device test with LabVIEW 8.6 software, the new NI PXIe-5663 6.6 GHz RF vector signal analyzer, the new NI PXIe-5673 6.6 GHz RF vector signal generator, and the new NI PXIe-1075 18-slot chassis, all of which take advantage of commercial technologies such as multicore processors and FPGAs.
Trend 1: Growing Number of Wireless Standards – Consumer devices such as cell phones and automobile in-dash entertainment systems often integrate multiple communications protocols. Many next-generation smart phones support a broad variety of standards such as GSM, EDGE, WCDMA, WiMAX, WLAN, DVB-H, MediaFLO, Bluetooth, and GPS. As a result, you may face the challenge of building automated test systems that are flexible enough to test these multiprotocol devices.
In the design phase, one approach to keeping up with the latest advances in wireless devices is through a software-defined test platform. Using algorithms based on the NI Modulation Toolkit for LabVIEW, you can measure custom physical layer characteristics. For example, researchers such as Dr. Umberto Spagnolini at the Polytechnic Institute of Milan are using LabVIEW to prototype algorithms for emerging standards such as WiMAX. These researchers can directly control system parameters, including channel coding, power, and modulation scheme, while adding fading and multipath interference to determine system immunity as a prototype of emerging WiMAX algorithms.
In production test, you can use a single system based on LabVIEW and PXI to test multiple protocols such as WCDMA, WLAN, WiMAX, DVB-T, and GPS by simply reconfiguring the measurements using standard-specific toolkits supplied by National Instruments Alliance Partners. In addition, you can combine PXI RF instrumentation with more than 1,500 PXI modules including high-speed digitizers, arbitrary waveform generators, and precision DC instruments to complete your automated test system.
Figure 2. LabVIEW, PXI, and NI TestStand test management software provide a scalable platform for parallel test.
Trend 2: Accelerating Demand for Wireless Technology – The manufacture of volumes of wireless devices has been steadily increasing for years. However, the combination of more accessible RF technology and the deployment of RF devices into developing countries has driven deployment to all-time highs. For example, Brazil, Korea, and India have already used or plan to use WiMAX base stations to deploy broadband Internet access to more remote locations with the forecasted number of worldwide WiMAX subscribers expected to reach 60 million in 2010. Furthermore, worldwide sales of mobile phones to end users surpassed 1.15 billion units in 2007 according to Gartner, Inc.
Through this incredible adoption, wireless technologies have become a commodity, and, in some cases, it is actually the test cost and not the materials that is a primary driver of product cost of goods sold (COGS). An effective way to reduce product COGS is to reduce device test time. You can achieve this by taking advantage of the latest, low-cost commercial technologies including multicore processors, field-programmable gate arrays (FPGAs), and high-speed PCI/PCI Express data buses. Because the PXI test platform incorporates these technologies, it can help you create high-performance test systems capable of parallel processing and parallel measurements. A diagram illustrating parallel algorithms and parallel device testing is depicted in Figure 2.
To illustrate the performance of the new NI PXIe-5663 6.6 GHz RF vector signal analyzers, consider a basic WCDMA test sequence versus traditional instruments. As Figure 3 shows, the new PXI RF vector signal analyzer delivers significant improvement in measurement speed. This performance can result in significant test cost savings for your application. For additional benchmarks, see page 10.
Figure 3. New PXI RF modular instruments deliver up to five times improvement in measurement speed with similar accuracy compared to traditional instruments. The results shown above were performed over 2,600 symbols.
Trend 3: Increasing SoC Complexity – The increasing integration of components on a single radio frequency integrated circuit (RFIC) is apparent. For example, while many traditional RFICs required only baseband and RF testing, many next-generation systems on a chip (SoCs) require you to measure precision DC and high-speed digital I/O as well. One prime example of this is the development of custom digital baseband interfaces such as DigRF. The DigRF standard uses a 3-wire serial protocol and provides a direct interface between baseband processors and RFICs.
The challenge of testing complex communications protocols, such as DigRF, is that digital handshaking between the baseband processor and SoC is required. To meet this application need, LabVIEW graphical system design offers access to programmable FPGA hardware, such as new NI R Series PXI modules equipped with high-performance Xilinx Virtex-5 FPGAs. FPGAs provide fast execution because they are inherently parallel and deliver deterministic (reliable) execution. Engineers have traditionally programmed FPGAs through hardware description languages such as Verilog or VHDL, which use low-level syntax to describe hardware behavior. Most test engineers do not have expertise in these tools. LabVIEW FPGA bridges this gap by abstracting the details of FPGA programming.
Meet Your Test Challenges
LabVIEW 8.6 enhances multicore and FPGA performance for software-defined RF test applications. As new multicore processors become available, RF measurement times will continue to decrease without requiring changes to the PXI RF instrumentation or LabVIEW programming, thereby ensuring maximum measurement performance, increased system longevity, and decreased capital investment. With these capabilities, you can meet both current and future wireless device test challenges.
Kevin Bisking is a senior PXI product manager. He holds a bachelor’s degree in electrical engineering from The University of Texas at Austin.
David Hall is an RF and communications product manager. He holds a bachelor’s degree in computer engineering from Penn State University.
This article first appeared in the Q3 2008 issue of Instrumentation Newsletter.
Print
Reader Comments | Submit a comment »
Legal
This material is protected under the copyright laws of the U.S. and other countries and any uses not in conformity with the copyright laws are prohibited, including but not limited to reproduction, DOWNLOADING, duplication, adaptation and transmission or broadcast by any media, devices or processes.