UWB Measurements | UWB device conformance testing

This page mentions UWB measurements for transmitter and receiver parts. It covers conformance tests for UWB device transmitter and receiver verification.

UWB technology spreads RF energy over wider bandwidth viz. 500 MHz. It follows IEEE 802.15.4 and IEEE 802.15.4z standards which defines PHY and MAC layers. It is used for various applications including ranging. It defines two versions of Physical layer i.e. HRP (High rate PHY) and LRP (Low rate PHY). UWB uses 16 frequency channels at different RF frequencies.

UWB Frame Structures

The figure depicts different frame configurations used in UWB system. As shown frame consists of SYNC, SFD, PHR, PHY Payload and STS fields for desired functions. Refer UWB frame structure >> for more information. Following table mentions UWB frequencies, UWB channels and UWB bandwidth used in different regions across the world.

UWB Channels UWB Center Frequency UWB Bandwidth Region used
0 399.36 MHz 499.2 MHz USA
1 3494.4 MHz 499.2 MHz USA, Europe
2 3993.6 MHz 499.2 MHz USA, Europe, Japan, Korea
3 4492.8 MHz 499.2 MHz USA, Europe, Japan, Korea
4 3993.6 MHz 1331.2 MHz USA, Europe
5 6489.6 MHz 499.2 MHz USA, Europe, China
6 6988.8 MHz 499.2 MHz USA, Europe, China
7 6489.6 MHz 1081.6 MHz USA
8 7488 MHz 499.2 MHz USA, Europe, Korea, China
9 7987.2 MHz 499.2 MHz USA, Europe, Japan, Korea, China
10 8486.4 MHz 499.2 MHz USA, Europe, Japan, Korea, China
11 7987.2 MHz 1331.2 MHz USA, Japan, Korea
12 8985.6 MHz 499.2 MHz USA, Japan, Korea
13 9484.8 MHz 499.2 MHz USA, Japan, Korea
14 9984 MHz 499.2 MHz USA, Japan, Korea
15 9484.8 MHz 1354.97 MHz USA, Japan, Korea

Test and measurement companies such as Rohde & Schwarz, Litepoint, NI (National Instruments), Keysight technologies develop test tools for UWB device measurements and its conformance tests. UWB device test tools allow measurements in time, frequency and modulation domains as per UWB conformance test requirement specifications.

UWB Transmitter Measurements

Following UWB transmitter measurements are conducted during UWB device conformance testing for its transmit functionality verification. These tests focus on verifying performance of the transmitter part. This UWB measurements are measured by UWB analyzer tool. UWB signal analyzer instrument is used to analyze UWB transmitted signal. Various parameters are required to be set to analyze the UWB signal in UWB test hardware and software.

UWB Measurements Description
Transmit Power Spectral Density (PSD) test It tests maximum transmit power from UWB device against limit set by national regulatory authorities in various countries for all the frequency channels. It should not exceed -41.3 dBm/MHz.
Spectral emission mask or PSD mask It is measured in frequency domain. It defines limits at various frequency offsets from center carrier frequency. Following mask is as per IEEE 802.15.4z. Here dBr stands for relative spectral limit compare to peak transmit power.
UWB PSD mask
Transmit power vs time It measures instantaneous transmit power across time scale.
Center frequency tolerance (CF Offset) UWB device should transmit at specified channel frequencies with frequency offset tolerance of about +/-20 ppm. This is as per IEEE 802.15.4z compliance specification.

UWB Receiver Measurements

Following UWB receiver measurements are conducted for its receive functionality verification. These tests focus on verifying reception and checking sensitivity limit of UWB DUT (Device Under Test). UWB signal generator instrument is used to generate UWB compliant signal for receiver tests. Various parameters are required to be set to generate the UWB signal both in the hardware as well as in T&M software. These parameters are channel number, center frequency, power level, waveform settings (e.g. number of frames), PHY configuration (Data, Preamble and STS related settings), MAC configuration (Frame control settings, addressing field settings, payload settings), impairments (AWGN, frequency offset, IQ DC offset, IQ gain imbalance, quadrature skew) etc.

UWB Measurements Description
Sensitivity test or Packet Error rate (PER) It is conducted to test minimum sensitivity level is as per requirement for different data rates. Less than 1% PER at specified receiver input level should be achieved for UWB DUT.
Interference test It measures interference susceptibility of the UWB receiver with respect to out of band unwanted channels which are non-adjacent.
Adjacent channel rejection This test measures performance of UWB receiver with respect to nearby undesired channels. It measures adjacent channel selectivity.
Maximum receiver input power level It measures maximum power which can be given to the receiver without any damage to it.

Other UWB Pulse related measurements

Following are the useful measurements provided by many UWB tools from Test and Measurement vendors.

UWB Measurements Description
Symbol Modulation accuracy It is the deviation between ideal symbol and measured symbol of the received signal. It is measured in EVM (%). Here EVM stands for Error Vector Magnitude. 100% is perfect number.
Chip clock error Device should chip at peak PRF of 499.2 MHz with +/- 20 ppm accuracy. (IEEE 802.15.4z)
Chip frequency error Center frequency of pulses are measured. Measured error should be less than +/- 20 ppm tolerance. RBW and VBW should be set to 1 MHz and 1 KHz respectively for this test.
Average/peak power (Preamble, data, STS) It measures average power and peak power of the preamble, data and STS fields.
Packet measurements Packet auto detection, data rate, payload length, PHY/MAC payload, number of erroneous packets, STS decoded data etc. Some of the UWB test analyzer provide these decoding results.
Ranging test Used for distance measurement using ToF (Time of Flight) method between initiator and responder (or receiver)

The other pulse related UWB measurements include pulse main lobe width (section : 16.4.5 of IEEE 802.15.4z) , pulse side lobe power (section : 16.4.5) , jitter, time domain mask etc.

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