Meeting the Challenges of Evolving Wireless Standards with Integrated Test and Validation Systems

tmily

Meeting the Challenges of Evolving Wireless Standards with Integrated Test and Validation Systems [Copy link]

This article provides an overview of the development of wireless technology and introduces a software-based integrated test and verification system architecture designed for emerging wireless technologies, as well as some successful user solutions.

In this era of rapid technological progress, technology leaders are facing the dilemma brought about by technological innovation. On the one hand, technological innovation wins a foothold in the market for companies and the opportunity to expand market share. But on the other hand, as the market matures, this competitive advantage that accelerates the company's growth is difficult to maintain for a long time, because competition will gradually commercialize and popularize products, and the original unique features of products will gradually become ordinary, requiring new technological innovations to bring new product highlights. Therefore, innovation has become a responsibility, forcing companies to continue to innovate in technology in order to maintain their existing leadership in the market, and to bring the results of innovation to the market in the shortest possible time. Take the telecommunications market as an example. As more and more functions are integrated into smaller and cheaper devices, mobile phones have become more and more complex. In the past, only a few mobile phones had multi-band functions, but now consumers generally require that their mobile phones should also have various functions such as Bluetooth, Wi-Fi and FM radio. With the emergence of various wireless communication standards, many mobile phone manufacturers hope to be the first to launch products with new functions to the market to ensure their market share. In this case, the design and testing process will become more difficult, and engineers will be under great pressure.

Figure 1: Complete integrated test and design verification system.

In order to keep pace with the technology-driven market, more and more companies are adopting a software-centric platform, combined with modular hardware, to connect the entire process from design to production - this is a solution based on virtual instrument technology. Using an open software platform, engineers can simplify and connect the design tool chain, thereby integrating more technologies into basic schematic modeling and simulation tools. The modular test architecture under the same software platform can verify the functionality of the product. By leveraging the openness of both the software platform and the modular architecture, manufacturers can use the same platform to connect design and testing, thereby reducing product time to market and addressing the challenge of increasingly complex product functions to highlight the advantages of their products.

Wireless technology standards are becoming increasingly diverse

Wireless technology has traditionally been considered (or even categorized as) a very deep part of the telecommunications industry, but now we are seeing this technology expand horizontally into many non-traditional markets. Wireless technology has become a default device feature, for example, chips integrate multiple wireless technologies on board; cars use Bluetooth technology for non-band communication; consumer products provide every conceivable wireless technology on a single device; industry relies on wireless sensors to provide real-time data to monitor and control various operations.

Looking back at wireless networks, we can see that these technologies can be roughly divided into a few major categories: wireless personal area networks (WPANs), local area networks, metropolitan area networks, and the latest regional area networks. We can also put wireless wide area networks under the category of cellular technologies.

Wireless Personal Area Networks (WPANs) are very active and include many different technologies. WPANs are at the heart of the wireless home because technologies such as Ultra-Wideband (UMB) are being widely used to solve the problem of too many cables in the home. UWB allows you to place a flat-screen TV anywhere in the home without cables.

ZigBee is targeted at the industrial sector, with wireless enabling HVAC, lighting and sensor controls to be placed anywhere without the need for cables.

Extending from the personal area network is the local area network (LAN). The most important technology here is 802.11, and 802.11a/b/g are the standards that people are familiar with.

Wireless Metropolitan Area Networks (WMANs) include the upcoming WiMAX. 802.16-2004 includes two fixed-point standards, one below 11 GHz and a line-of-sight standard extending to 66 GHz. Since 802.16e adds roaming capabilities to WiMAX, it now looks like a very promising technology.

802.22 is a brand new standard under development. This wireless regional area network (WRAN) operates in the frequency range of 54 to 862MHz standard TV channels. This cognitive technology uses TV frequency bands that have never been used before and are available. Since the range of WRAN can exceed 40km, 802.22 will most likely provide support for WiMAX.

If we plot the various standards along a timeline, it becomes immediately clear that many technologies are being developed at an unprecedented pace, and that new standards are being developed at an unprecedented pace. Many technologies (such as AMPS, 802.11, GSM, and RFID) have been around for several years, but more and more standards have been developed in recent years to address the growing needs and demands for data.

Figure 2

Please pay attention to the problem of standard proliferation we are facing. Before 2000, it was enough for each device to have only one or two wireless technologies. But now, with multiple standards coexisting, it is necessary for devices to implement multiple standards at the same time in order to be launched on the market and provide seamless operation for users. This places stringent requirements on designers, test engineers and manufacturers.

The innovation of wireless technology will bring more standards and make the above trends more complicated. The following are some emerging wireless standards that are in the research and development stage:

* OFDM (Orthogonal Frequency Division Multiplexing) - This technology is becoming increasingly popular and is being implemented in many new standards.

* 4G cellular technology.

* Cognitive Radio - Part of the 802.22 standard, this technology searches for empty spectrum to use when there is a conflict or traffic. Traffic is then moved to other unused spectrum.

* Ad Hoc and sensor networks

* Software Defined Radio (SDR)—SDR uses reconfigurable hardware, such as FPGAs, so that the hardware can be adapted to changing network requirements.

* Multiple antenna systems (MIMO)—multiple input, multiple output—in these systems, multiple antennas are used to increase system capacity.

* Ultra-Wideband (UWB) - On first generation devices (3.1 to 4.8GHz), each channel uses the full 528MHz and transmits data at 480Mbit/s.

* Coexistence of multiple wireless standards—Standards organizations are working to address these challenges.

Complete integrated test and design verification system

With all these new standards emerging and coexisting at the same time, equipment manufacturers, test engineers, and designers are facing many challenges. The purchase cycle of RF equipment is usually 5 to 7 years, but the launch cycle of new standards and new technologies is every two years. Therefore, it is obvious that the purchased RF equipment will become outdated quickly due to the rapid update of market demand.

How to solve these problems? What platform can be scalable to handle the rapid technological advancements in the wireless market? Let's take a look at the diagram depicting a complete, integrated test and design verification system.

Just as software radio distinguishes between hardware and software, let's focus on these two aspects - hardware and software - as we discuss how virtual instrumentation technology can provide solutions to these challenges. Typically, the device under test (DUT) contains a variety of different functions that need to be verified through external test hardware. These functions may include DC, AC, audio, video, IR, and RF, etc. As more functions are concentrated in this device under test, the test hardware platform needs to become more open and modular so that it can be upgraded and meet the latest needs.

The software part represented by dark blue in the figure needs to complete three key tasks - system control for issuing commands to the test hardware, signal analysis processing to convert raw data into meaningful results, and visualization functions to display measurement results in an effective way. In addition, the software platform needs to be open so that users can interact with electronic design automation (EDA) software to integrate more technologies into basic schematic modeling and simulation tools, and finally use embedded development tools to automatically convert these electronic designs into physical chips or boards.

NI has foreseen this industry trend and has expanded its modular instrument product line to meet user needs by adopting various advanced business technologies at an astonishing release rate (one product every two working days).

The functions provided by these modular hardware range from temperature and pressure to RF vector signal generation and acquisition, which can be seamlessly integrated into the open PXI platform. In addition, the PXI platform ensures synchronization capabilities by using the built-in high-bandwidth backplane and timing and triggering bus. It is worth mentioning that this platform is upgradeable. When a new processor is launched, the processor can be upgraded without abandoning the entire platform, and engineers can test new features by choosing one of the thousands of existing modules. This provides a huge advantage over traditional instruments. Because once you buy a traditional instrument, you will be bound to the processor or test features in that instrument until the next equipment update (usually 5 to 7 years).

Figure 3

From the software side, the Modem Toolkit for LabVIEW and LabWindows/CVI (an ANSI C development environment) provides a foundation for developing industry-specific communication standards, such as CDMA2000, GPS, UWB, GSM, Bluetooth, ZigBee, etc. With this flexible foundation, engineers can develop standard-compliant software on the same platform as new standards emerge and are approved.

Application examples of RF platforms integrating software and hardware

Let's take a look at the following two examples to understand how the hardware-software integrated RF platform can meet user needs:

1. User Solution 1: Prototyping a MIMO-OFDM 4G System

This is a representative example of how to quickly prototype and develop a system using this platform.

This is a MIMO-OFDM 4G system developed at the University of Texas at Austin. Under the guidance of Professor Robert Heath of the UT Wireless Network and Communications Laboratory, three students designed a prototype of this 4G system in 6 weeks.

The tools they used included NI RF vector signal generators, RF vector signal analyzers, modem toolkits, and LabVIEW software. In addition, researchers at the University of California, Berkeley are also using the same equipment to conduct similar research.

Using the same system, some companies have developed applications for the growing RFID market, such as tire pressure monitoring and keyless entry. Collecting responses from RFID tags or readers requires very fast generation and triggering speeds, and the triggering performance of the NI PXI platform with tens of picoseconds resolution can well meet all the requirements of the task.

2. User Solution 2: Software Radio Platform for Spectrum Monitoring

Let's look at an example from the local Chinese market. Chengdu Huari Communication Company (Huari Telecom) is a large developer and manufacturer of radio direction finding systems. They need a solution for spectrum monitoring, direction finding and signal identification. This system needs to provide users with better performance to monitor signals within and outside the government-controlled frequency bands, while also using signal identification and direction finding functions to identify illegal transmissions or interference sources.

Using the NI PXI-5660 PXI vector signal analyzer and software developed in the LabVIEW environment, Huari developed the HR-100, a patent-pending wideband radio receiver and monitoring system. This system can be used as both a radio receiver and an RF vector signal analyzer to detect modern wideband digital communication signals as well as traditional narrowband analog broadcast signals. In addition, the system can be configured as a single-channel receiver or a multi-channel directional system. Because this new system uses an open software radio platform, the HR-100 can complete standard and custom measurements that previously required multiple dedicated, independent instruments. In addition, the company can upgrade this open system to meet the needs of future wireless standards, which is critical for the rapid changes in wireless standards. Recently, the system has passed the rigorous verification tests of relevant departments.

Author: Zhu Jun

Technical Marketing (China) Manager

Email:June.zhu@ni.com

Joseph Kovacs

RF Platform Product Marketing Manager

Email:Joseph.Kovacs@ni.com

National Instruments