Test-and-Measurement » UWB Measurements and UWB Device Conformance Testing

UWB Measurements and UWB Device Conformance Testing

uwb measurements conformance testing receiver transmitter

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

Introduction

UWB (Ultra-Wideband) technology spreads RF energy over a wide bandwidth, typically 500 MHz. It adheres to IEEE 802.15.4 and IEEE 802.15.4z standards, which define the PHY (Physical) and MAC (Media Access Control) layers. UWB is used for various applications, including ranging.

The standards define two versions of the Physical layer: HRP (High Rate PHY) and LRP (Low Rate PHY). UWB utilizes 16 frequency channels at different RF frequencies.

UWB Frame Structures

The figure above depicts different frame configurations used in a UWB system. As shown, a frame typically consists of SYNC, SFD, PHR, PHY Payload, and STS fields for desired functions.

The following table outlines the 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), and Keysight Technologies develop test tools for UWB device measurements and its conformance tests. These UWB device test tools allow measurements in the time, frequency, and modulation domains, as per UWB conformance test requirement specifications.

UWB Transmitter Measurements

The following UWB transmitter measurements are conducted during UWB device conformance testing to verify its transmit functionality. These tests focus on verifying the performance of the transmitter. These measurements are typically made using a UWB analyzer tool or a UWB signal analyzer instrument. Various parameters need to be configured to analyze the UWB signal correctly in the UWB test hardware and software.

UWB Measurements	Description
Transmit Power Spectral Density (PSD) test	It tests the maximum transmit power from the UWB device against limits set by national regulatory authorities in various countries for all frequency channels. It should not exceed -41.3 dBm/MHz.
Spectral emission mask or PSD mask	It is measured in the frequency domain and defines limits at various frequency offsets from the center carrier frequency. The following mask is as per IEEE 802.15.4z. Here dBr stands for the relative spectral limit compared to the peak transmit power.

Transmit power vs time	It measures instantaneous transmit power across a time scale.
Center frequency tolerance (CF Offset)	The UWB device should transmit at specified channel frequencies with a frequency offset tolerance of about +/-20 ppm. This is as per the IEEE 802.15.4z compliance specification.

UWB Receiver Measurements

The following UWB receiver measurements are conducted for its receive functionality verification. These tests focus on verifying reception and checking the sensitivity limit of the UWB DUT (Device Under Test). A UWB signal generator instrument is used to generate UWB compliant signals for receiver tests.

Various parameters need to be set to generate the UWB signal, both in the hardware and in the T&M software. These parameters include channel number, center frequency, power level, waveform settings (e.g., the number of frames), PHY configuration (Data, Preamble, and STS related settings), MAC configuration (Frame control settings, addressing field settings, payload settings), and 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 if the minimum sensitivity level meets the requirement for different data rates. Less than 1% PER at the specified receiver input level should be achieved for the UWB DUT.
Interference test	It measures the interference susceptibility of the UWB receiver with respect to out-of-band unwanted channels that are non-adjacent.
Adjacent channel rejection	This test measures the performance of the UWB receiver with respect to nearby undesired channels. It measures adjacent channel selectivity.
Maximum receiver input power level	It measures the maximum power that can be given to the receiver without causing any damage.

The following are useful measurements provided by many UWB tools from Test and Measurement vendors.

UWB Measurements	Description
Symbol Modulation accuracy	It is the deviation between the ideal symbol and the measured symbol of the received signal. It is measured in EVM (%). Here EVM stands for Error Vector Magnitude. 100% represents a perfect number.
Chip clock error	The device should chip at a peak PRF of 499.2 MHz with +/- 20 ppm accuracy (IEEE 802.15.4z).
Chip frequency error	The center frequency of pulses are measured. The 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 the 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 UWB test analyzers provide these decoding results.
Ranging test	Used for distance measurement using the ToF (Time of Flight) method between the initiator and responder (or receiver).

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, and the time domain mask.