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A Software-Based Test Architecture for Emerging Wireless Technologies

Joseph E. KovacsProduct Marketing Manager

RF and High Frequency MeasurementsNational Instruments

www.ni.com/rf

My name is Joseph Kovacs, and I am the Product Marketing Manager for the RF and High Frequency Measurements division of National Instruments in Austin, Texas.

I wanted to spend a few minutes talking about the new, emerging wireless technologies and how a software-based test architecture can provide a platform for design, development, test, and manufacturing for these new devices hitting the market.

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Inundated With Standards802.11

802.11a

802.11u 802.11j 802.11i

802.11k

802.11j802.11h

802.11g802.11f

802.11e802.11d

802.11a

802.11b

802.11t802.11s

802.11r

802.11n802.11v

WiMAX –802.16-2004

ZigBeeRFID

UWB

TD-SCDMAUMTS

GPRS

cdma2000

EDGE

HSDPA

802.22

WiMAX –802.16e

802.20GSM

802.15.1

You can see from this slide that these wireless standards are really inundating the market. Its really hard or almost impossible to keep up will all the standards bodies, the latest decisions, and the rapid changes in the market.

Here are several of the standards in our time horizon when you look at the market today. Actually, there are many more older technologies like AMPS, IS-95, IS-136, just to name a few that are not listed here that are giving way to the new ones listed on this slide.

Take for example, 802.11. The success of the 802.11 standard and its adoption has fueled even more work on this standard. Some of the more notable are:

802.11e – Enhancement to support devices with Quality of service requirements802.11n – Enhancements for high throughput of at least 100 Mbit/s. 802.11n incorporates MIMO.802.11r – Fast roaming 802.11s – Mesh networks

If we look at wireless wide area networks:One of the 3G standards - UMTS - has still to be fully rolled-out, but has already given way to 3.5G HSDPA (High Speed Downlink Packet Access). 4G is already being debated.

The list seems to be endless.

These is a reason this is happening.

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Traditionally, wireless was thought of or even relegated to the vertical telecommunications industry segment. Now we see this technology being spread out horizontally into many non-traditional markets.

Now, it is expected that wireless is part of the functionality of the device.

Chips package multiple wireless technologies onboard. Cars implement Bluetooth for hands-free operation. Cell phones offer multiband functionality along with Bluetooth, Wi-Fi, and FM radio. Consumer devices offer every conceiveable technology in a single device. Industry relies on wireless sensors to provide real-time data to monitor and control various operations.

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Today’s Design Challenges: Converging Complexity, Unfamiliar Technologies

Automotive Telematics SystemAutomotive Telematics System

For example, a simple AM/FM/cassette car radio from a decade ago has now become an automotive telematics module that integrates audio, video, GPS navigation, diagnostics, and wireless communications functions into this single subsystem. Now, the engineer has to integrate a bewildering array of data, audio, video, and RF signal sources along with acquisition tools to adequately validate system performance. The mixed functionality of the design causes an exponential increase in the validation effort.

This poses a real challenge to the engineer designing these systems.

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Wireless Networks

0 10m 100m 40km

WPAN WLAN WMAN WRAN

•WPAN – Wireless Personal Area Network

•WLAN – Wireless Local Area Network

•WMAN – Wireless Metropolitan Area Network

•WRAN – Wireless Regional Area Network

Looking back at a wireless network, we see multiple technologies falling into some major catagories: Wireless personal area networks, local, metropolitan, and more recently, regional area networks. We can also include the Wireless Wide Area Networks to account for cellular technologies.

We can match-up some specific technologies to these major catatories.

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Wireless Networks

0 10m 100m 40km

802.16-2004 802.22RFIDUWB

Bluetooth

ZigBee 802.11802.16e

Wireless personal area networks are very active and contain many varied technologies. WPANs make up the backbone for the wireless home since many of these technologies, like Ultra-Wideband, are being look to to solve the problem of have too many cables in the home. UWB will allow one to place a flatscreen anywhere without cables.

ZigBee is targeted at the industrial segment where wireless will allow for HVAC, lighting, and sensor controls to be placed anywhere without wires.

Extending out from the personal area networks, is the local area networks. The major player here is 802.11. 802.11 a/b/g are common household names.

Wireless Metropolitan Area Networks include the up and coming WiMAX. 802.16-2004 includes two fixed-point standards, one below 11 GHz and the other a line-of-sight standard extending up to 66 GHz. 802.16e looks like it will be a very promising technology since it add roaming capability to WiMAX.

802.22 is a new standard being developed. This Wireless Regional Area Network operates in the 54 to 862 MHz range, the frequencies of standard television channels. This cognitive technology uses the unused, available, television frequency bands. 802.22 will most likely provide a backbone for WiMAX since the range of WRAN extends to over 40 km.

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RFID

GSM

802.15.1

EDGE

GPRS

Evolving Wireless Standards

1990 1995 20052000 2010

802.11

802.11a

802.11u

802.11j

802.11i

802.11k

802.11j

802.11h

802.11g

802.11f802.11e

802.11d

802.11b

WiMAX – 802.16-2004

UWB

TD-SCDMA

UMTS

cdma2000

HSDPA

802.22

WiMAX – 802.16e

802.20AMPS

IS95

IS136

IS54

ZigBee

802.11n

Plotting the different standards on a timeline, it becomes instantly apparent how many technologies are being developed. The rate at which these new standards are being developed is increasing at an extreme rate with no letup in sight. Many technologies have existed for years like AMPS, 802.11, GSM, and RFID. But in the last few years, more and more standards are being developed to deal with the increase in the need for and demand for data.

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RFID

GSM

802.15.1

EDGE

GPRS

Evolving Wireless Standards

1990 1995 20052000 2010

802.11

802.11a

802.11u

802.11j

802.11i

802.11k

802.11j

802.11h

802.11g

802.11f802.11e

802.11d

802.11b

WiMAX – 802.16-2004

UWB

TD-SCDMA

UMTS

cdma2000

HSDPA

802.22

WiMAX – 802.16e

802.20AMPS

IS95

IS136

IS54

ZigBee

802.11n

Notice the log-jam of standards we are facing. Prior to 2000, only one or two wireless technologies were sufficient per device. Now, due to the number of standards existing at the same time, it is necessary for devices to implement multiple standards to compete in the market and provide seamless operation for the user. This places extreme demands on the designer, test engineer, and manufacturer.

Here we can see that the lines are blurred between these technologies.

How is this situation being delt with in the market?

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Multiple Technologies on a Single Chip

• Chip manufacturers strategy– Unclear which technology will win– Package as many standards/technologies as possible on a

single chip

Chip manufacturers are packaging multiple technologies or standards on a single chip. This way, any technology is available and can be implemented. It is unclear which standard will ultimately be the winner, so it makes sense to package all on a single chip.

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Multiple Technologies on a Single Device

• Standards for interoperability of multiple technologies– For Example: UWB and Bluetooth

•4096-color screen

•XHTML Browser

•Wireless phone-to-phone or phone-to-computer connectivity

•Bluetooth•HSCSD•GPRS•EGSM/GSM

•Phone•Email•SMS•browser•Bluetooth•Quad-band 850/900/1800/1900 MHz GSM/GPRS

Devices that implement these chips are able to offer customers multiple functions on a single device. Notice all the functionality that is offered in the Blackberry by Research in Motion and the N-Gage gaming cell phone from Nokia.

A great example of what is happening in the market is the recent development of the UWB and Bluetooth groups getting together to ensure the smooth operation between the two personal area network technologies.

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Ongoing Work in the Wireless Market

• OFDM• 4G Cellular• Cognitive Radio• Ad Hoc and Sensor networks• Software Defined Radio (SDR)• Multiple Antenna Systems (MIMO)• Ultra-Wideband (UWB)

– 3.1 to 4.8 GHz for first generation devices• Multiple Wireless Standards Coexistence

This trend is only going to continue to increase in complexity as new work is ongoing to offer better services in these areas:

•OFDM (Orthoginal Frequency Division Multiplexing) – this technique is gaining popularity and is being implemented in many of the new standards.•4G Cellular•Cognitive Radio – this technique, part of the 802.22 standard, searches for empty spectrum and uses it until interference or traffic appears. Traffic is then diverted to other unused spectrum.•Ad Hoc and Sensor networks•Software Defined Radio (SDR) – SDR uses reconfigurable hardware, like an FPGA, to allow hardware to adapt 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) – uses a full 528 MHz per channel to transmit data at 480 MBit/s in the first generation devices at 3.1 to 4.8 GHz•Multiple Wireless Standards Coexistence – standards groups are appearing to address these challenges.

•So we see there is a lot of work and more that will continue in the wireless space – and it is not going to letup.

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RF Equipment Buying Cycle

• 5-7 years is the life of RF equipment• New standards/functionality implemented into devices on a continual basis

With all these new standards appearing and coexisting at the same time, it poses many challenges to the device manufacturer, test engineer, and designer especially since the buying cycle is 5 to 7 years for RF equipment and new standards and functionality are being implemented into devices on a continual basis.

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RFID

GSM

802.15.1

EDGE

GPRS

Evolution of Wireless Standards

1990 1995 20052000 2010

802.11

802.11a

802.11u

802.11j

802.11i

802.11k

802.11j

802.11h

802.11g

802.11f802.11e

802.11d

802.11b

WiMAX – 802.16-2004

UWB

TD-SCDMA

UMTS

cdma2000

HSDPA

802.22

WiMAX – 802.16e

802.20AMPS

IS95

IS136

IS54

ZigBee

802.11n

Looking at the standards timeline again, new technology or standards are appearing on the market every couple of years. If the usual equipment buying cycle is 5 to 7 years and standards are being developed every couple of years, it is immediately apparent that RF equipment purchased is quickly obsolete due to the swift pace at which these are appearing.

So what is one solution to the problem, and what platform scales to account for the rapid technological advances in the wireless market?

Just as Software Defined Radio decouples hardware from software, let’s focus on these two aspects – hardware and software – as we discuss how virtual instrumentation provides a solution to these challenges.

Let’s first start with hardware that grows as technology and functionality changes.

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TestHardware

TestHardware

Design Under Test

Test Software

Embedded Software Development

Tools

System Clocking and Triggering

Analog Output• DC, AC

• Audio, Video• IF, RFSystem Control

Signal Processingand Analysis

Visualization

NetworkingDigital Output

•Serial•Parallel

Analog InputDC, AC

• Audio, Video• IF, RF

Digital Input•Serial

•Parallel

Embedded Processor

PowerMemory

Design Simulation Tools

Transceiver

Logic PeripheralInterfaces

Hardware: Integrated Test and Design Verification Environment

This slide shows how virtual instrumentation integrates hardware and software throughout the development cycle.

The section in orange represents the various hardware that is needed to test a device. The hardware surrounds or envelopes the device under test and provides the necessary input and output interfaces.

The DUT fits into this environment and all functionality is exercised via the surrounding hardware.

The software part, in dark blue, performs three critical tasks - system control for issuing commands to the hardware, signal processing and analysis to turn the pure data into useful measurements, and visualization for representing the measurements in a useful manner.

In the rapidly changing wireless market, the virtual instrumentation platform is excellent since it is able to grow and change to advances in the market.

Notice how this is possible on the hardware side.

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DAQ AND CONTROL:•Multifunction I/O•Reconfigurable I/O•Digital I/O•Analog Input/Output•Vision and Motion•Counter/Timers

INSTRUMENTS:•Oscilloscopes•Digital Waveform Generator/Analyzers•Digital Multimeters•Signal Generators•Switching•RF Vector Signal Generation and Analysis

INTERFACES:•GPIB •SCSI + Enet•Boundary Scan/JTAG•CAN + DeviceNET•RS-232/RS-485•VXI/VME

Wide Range of PXI Modules

On the left, we see a few of the over 1,000 PXI modules available today. These modules provide functionality ranging from temperature and strain, to RF Vector Signal Generation and Acquisition.

PXI - THE industry standard for modular instruments - is built on the modular and scalable CompactPCI specification and the high-speed PCI bus architecture. As a result, PXI products maintain complete interoperability with CompactPCI, offering superior mechanical integrity, easy systems integration, and more expansion slots than desktop computers.

On great advantage of the modular, PXI platform is it’s upgradeability.

Now, how many times have you purchased a computer only to find out that a faster processor is available just a few weeks after your purchase. With this modular PXI platform, as faster processors become available, the processor can be upgraded without having to obsolete the whole platform. In addition, since the modules all plug into the PCI bus, timing and triggering issues are all handled on the backplane meaning that your code does not have to change – you don’t need to put in delays in your code - to deal with the speed increase.

This provides a great advantage to manufacturing since throughput can increase at the speed at which faster processors become available in the market thus preserving your initial capital investment. This provides a great advantage over traditional instruments that cannot be upgraded in this manner. Once you make a purchase, you are locked in to that processor speed until the next equipment purchase, which as we mentioned, is from 5 to 7 years in the RF market.

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• Protect investments in existing equipment

• Allows use of the latest technologies

• Optimize system resources and minimize costs

• Allow system to meet unique requirements through flexible architectures

PXI supports Hybrid Test Systems

Added to the functionality that is available by adding the various modules, current test equipment can also be used since PXI provides a way to connect via LAN, GPIB, MXI-2, and MXI-4.

This is a great way to step into the technology to gain the speed and performance advantages without having to obsolete existing test equipment that may be an integral part of your design, test, or manufacturing process.

This provides a nice transition to the fast and flexible virtualinstrumentation platform.

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• Measurement Performance– 250 kHz to 2.7 GHz– 20 MHz Real-Time Bandwidth– -145 to +10 dBm power level– 50 ppb frequency accuracy

• Flexible Modulation Software– ASK, FSK, MSK, GMSK, PSK, QPSK, /4 DQPSK, QAM, AM, FM, PM, Custom

• Deep Onboard Memory– 32, 256, and 512 MB memory options

RF Vector Signal GenerationNI PXI-5671 2.7 GHz RF Vector Signal Generator with Digital Upconversion

For the RF and wireless market, National Instruments just released the 5671 RF Vector Signal Generator with Digital Upconversion capability. The Digital Upconversion capability really fuels the speed of signal generation with this module. In one customers applications, signal generation times went from over one minute to 4 seconds. That is an incredible speed increase.

The 5671 ships with the Modulation Toolkit which provides the ability to generate all the standard modulation formats in addition to custom formats via access to the symbol table.

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RF Vector Signal AnalyzerNI PXI-5660 2.7 GHz RF Vector Signal Analyzer• Measurement Performance

– 9 kHz to 2.7 GHz – 20 MHz real-time bandwidth– 80 dB SFDR– 50 ppb frequency accuracy– 30% of size, weight of competing instruments

• Wide Range of Analysis– Modulation and Spectral Measurement Toolkits

• Measurement Throughput– 30-200x faster RF measurements

On the acquisition side, we have the very popular 5660 RF vector signal analyzer.

With 20 MHz of real-time bandwidth along with the 132 Mbytes per second over the PCI bus, this offers a big speed improvement over a 1 Mbyte per second GPIB bus instrument.

When used with the Modulation Toolkit, the 5660 can demodulate all the standard and custom modulation formats.

As is the case with the generator and analyzer, the functionality of the modules is derived from the software. As long as the module delivers the needed key specifications, new functionality can be developed insoftware, or added with the addition of other modules.

As new wireless devices include more and more functionality along with multiple standards, the test platform can grow with the addition of these technologies. For example, if vision capability becomes necessary for test, the PXI platform offers this functionality and a lot more. This really makes the PXI platform unique since it allows for disparate functions to be included in one platform.

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Software: Solving Application Specific Requirements

Looking at the software side, the Modulation Toolkit for LabVIEW and LabWindows/CVI which is an ANSI C development environment, provides a foundation to develop the standards listed here and many more. With this flexible foundation, as new standards are approved and appear, software can be developed to the standard on this same platform.

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• Analog and Digital modulation formats– AM, FM, PM– ASK, FSK, MSK, GMSK, PAM, PSK, QAM

• Visualization– 2D and 3D Eye, Trellis, Constellation

• Modulation Analysis– BER, MER, EVM, burst timing, frequency

deviation, ρ (rho)• Impairments

– Additive White Gaussian Noise (AWGN)– DC offset, Quadrature skew, IQ gain

imbalance, phase noise• Equalization, Channel Coding, Channel

Models

Measurements, Modulation, and Visualization Modulation Toolkit for LabVIEW and LabWindows/CVI

The Modulation Toolkit ships with every vector signal generator. This allows all the standard modulation formats to be generated, even custom formats. This way, the code is already written for the standard formats – then, you can build on top of these basic building blocks.

The standard eye, trellis and constellation diagrams are already written as well as analysis functions that can be used with any PXI signal analyzer. Functions are written for MER and EVM as an example. And, over 100 source code examples ship with the toolkit providing a great starting point or, in some cases, all you need to get up and running.

On the signal generation side, you also have the ability to inject impairments into the system such as Gaussian Noise, IQ gain imbalance, and phase noise, and these impairments then can be measured at the output of the device with a signal analyzer using the Modulation Toolkit. You will find that while many tools offer a software modeling environment for wireless and other communication systems, they do not allow for impairments. The Modulation Toolkit takes this a step further – impairments not only can be modeled in software, but also can be generated by the hardware.

In addition to the tremendous amount of flexibility, the building blocks exist so you can start building your system quickly.

Take for instance a digital communications system.

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Dem

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Chan

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ecod

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Sour

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ecod

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Sour

ce C

odin

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Modu

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Upco

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Chan

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Digital Communication System

This slide shows basic blocks in a digital communications link.These blocks are for source coding, channel coding, modulation and upconversion on the transmit side.

On the receive side, the blocks include downconversion, demodulation, channel decoding and source decoding.

A real-world communication link contains a physical channel over which the transmission will occur. In our discussion here, wireless would be the channel. Other examples of physical channels also would include, but are not limited to, fiber optic and copper.

The Source coding block typically involves data compression. For example, the ATSC standard for digital video broadcast (DVB) specifies MPEGII encoding for the image to be transmitted. A-law, Mu-law, and JPEG, are examples of other types of compression algorithms commonly used in source coding.

The Channel coding block typically involves adding redundant bits to the data stream to reduce the receiver’s susceptibility to noise and interference in the channel. The ATSC standard specifies Reed Solomon and Trellis coding as channel coding blocks. 802.15.4 (ZigBee) standard specifies differential encoding and bit to chip mapping to add redundancy. The output of the channel coding block is still a series of 0s and 1s.

The next block in the chain is the modulation block which converts the bits into an in-phase (I) and quadrature-phase (Q) data. This block typically also involves the step of pulse shaping to reduce inter-symbol interference and reduce bandwidth.

The next block in the link involves analog upconversion to the RF frequency at which the signal is transmitted.

A mirror image of these steps is repeated at the receiver side.

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Digital Communication System – Design

PXI

Here is where the real beauty of the Modulation Toolkit along with the PXI hardware stands out.

If you notice, the same blocks of functionality as found in a communications systems are also icons of functionality contained in the Modulation Toolkit. This way, a new communications system or new wireless standard can quickly be prototyped and the design evaluated along with impairments added to stress the design.

Modeling a new wireless standard with software does not stop there. Using the PXI hardware allows one to send and receive the signalwirelessly – in this case.

As new wireless standards appear, the platform can respond and adapt to your changing needs. This makes this platform excellent for the wireless market.

Look how this was done almost two years ago with a 4G prototypedsystem.

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Prototyping a MIMO-OFDM 4G System

Prof. Robert Heath, UT, AustinWireless Networking and Communications Group (WNCG)

This is an outstanding example that illustrates how quickly systems can be prototyped and developed with this platform.

This is a MIMO-OFDM 4G system developed at the University of Texas here in Austin. Under the direction of Professor Robert Heath in the Wireless Networking and Communications Group at UT, 3 students in a period of 6 weeks prototyped this 4G system.

In the front panel at the top right, you see two pictures of the UT campus – the top one is the original picture and the bottom one is the recovered picture after it was transmitted via the 4G system. You can see the constellation diagram and some of the measurements that were made.

They used the NI RF vector signal generator, RF vector signal analyzer, the Modulation Toolkit and LabVIEW.

Other similar research using the same equipment is underway at the University of California at Berkeley.

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TPMS, Keyless Entry, & RFID

With the same system, our customers have developed applications for growth markets in Tire Pressure Monitoring, Keyless entry and RFID.

The triggering capability of the platform, with tens of picoseconds of resolution, provides what is needed to generate and quickly trigger to acquire the response back from an RFID tag or reader.

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Frequency Agile Spectrum Monitoring & Access –Cognitive Radio

With the speed, real-time bandwidth, and small size of the system, this makes it a great fit for spectral monitoring applications and cognitive radio like in 802.22.

These are just a few of the examples of applications that are possible with the platform.

To continue to expand the capability of the PXI platform, National Instruments works with many partners and members of the PXI alliance.

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•Input Frequency Range: 4.9 to 6 GHz

•Output Frequency Range: 1.1 to 2.2 GHz

•Pass-Through: DC to 3 GHz

•Low Cost Solution

•10 MHz Reference Input

•Plug and Play Software Interface

•2 Slot PXI

•+15 dBm Input Power

•Built-in Programmable Attenuator

7205 PXI Downconverter

7207 PXI UP and Downconverter

ASCOR PXI RF Modules

The PXI Systems Alliance contains over 65 members – one listed here is ASCOR.

ASCOR produces RF and Microwave products and is based in Silicon Valley.

The 7205 and 7207 modules as seen here extend the frequency range of the PXI platform out to 6 GHz. Using these modules, 802.11a tests can be performed with the PXI platform.

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SeaSolve Software - Compliance Testing an IEEE 802.15.4 (ZigBee) Device

We also work with software partners to extend the platforms capability.

SeaSolve Software, based in Richmond, California, has produced 802.15.4 compliance software using the PXI RF hardware and software.

This software provides pass/fail results according to the standard.

In the beginning of May 2005, SeaSolve issued a press release announcing that TUV Rheinland of North America which is a subsidiary of TUV Rheinland Group who is a global leader in compliance engineering, testing and certification, selected SeaSolve’s ZigBee test software and the PXI platform for compliance testing of ZigBee devices.

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SeaSolve Software 802.11 Testing

SeaSolve also has software using the PXI platform for 802.11 testing.

As you can see from the examples and the flexibility of the platform, a virtual instrumentation approach provides a great way to deal with the constant change in the wireless market.

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Thank You