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IEEE Std 802.15.4z-2020
IEEE Standard for Low-Rate Wireless Networks
Amendment 1: Enhanced Ultra Wideband (UWB) Physical Layers (PHYs) and Associated Ranging Techniques
two devices. Similarly, an accurate location estimate for a mobile device can be determined, for example,
when its distance from a number of fixed devices (of known location) is ascertained.
The UWB PHYs specified in Clause 15 and Clause 18 optionally include facilities to enhance ranging, and
these ERDEVs are referred to as the high rate pulse repetition frequency UWB PHY based enhanced
ranging capable device (HRP-ERDEV) and the low rate pulse repetition frequency UWB PHY based
enhanced ranging capable device (LRP-ERDEV), respectively.
The HRP-ERDEV incorporates an STS, see 15.2.9, generated by an AES-128 based deterministic random
bit generator (DRBG). Only valid transmitters and receivers know the correct seed to generate the sequence
for transmission and for reception to cross correlate and accumulate to produce a channel impulse response
estimate from which to accurately determine the receive time.
The LRP-ERDEV supports challenge-response authenticated ranging with distance commitment on secret
data payload. These ranging schemes are described in 6.9.8.
The fundamental measurements for ranging are achieved using a Data frame Ack frame sequence
transmitted frame and a response frame. For example, a ranging exchange may consist of a Data frame and
its acknowledgment. As another example, the response could be a Data frame. A frame used for a ranging
measurement The Data frame has the Ranging field set to indicate ranging and is referred to as a ranging
frame (RFRAME).
Generally, an RFRAME is indicated by the Ranging field being set in the PHR, however
as described in 15.2, the HRP-ERDEV has a packet configuration where the PPDU has no PHR (or data) but
consists solely of the SHR and STS. This is STS packet configuration three (SP3). SP3 packets are treated as
RFRAMEs.
Ranging capabilities are enabled in an RDEV a ranging-capable device (RDEV) with the MCPS-
DATA.request primitive
and with the MLME-RX-ENABLE.request primitive. Whenever ranging is
enabled in an RDEV, the RDEV delivers
accurate transmit and receive time timestamp reports to the next
higher layer as a result of events at the device antenna. The
times that are reported are timestamp that is
reported is measured relative to the ranging marker (RMARKER). For all PHYs the RMARKER is defined
to be the time when the beginning of the first symbol
following the SFD of the PHR of the RFRAME is at
the local antenna.
For UWB PHYs this shall be the peak pulse location associated with the first chip
following the SFD. An HRP-ERDEV can use the STS to determine time of arrival and then derive the
RMARKER time.
The relative positioning and locating methods supported by this standard are: single-sided two-way ranging
(SS-TWR), double-sided two-way ranging (DS-TWR) and one-way ranging (OWR) for the time difference
of arrival (TDOA) localization method.
In a typical implementation, the transmit and receive time reports will be captured by the transmitter and
receiver, and then adjusted to account for the time difference between the internally captured time and the
time the RMARKER actually launches or arrives at the antenna. These offsets are separately defined for
transmitter and receiver as the configurable PIB attributes phyTxRmarkerOffset and phyRxRmarkerOffset.
The TxRangingCounter and RxRangingCounter values within the RangingReportDescriptor (defined in
Table 8-90a) parameter of the MCPS-DATA.confirm and MCPS-DATA.indication primitives report
RMARKER transmit and receive times as specified in 8.3.
The next higher layer can estimate the relative clock offset between the remote transmitter and the local
reference clock at the receiver based on the reported SRMARKER receive ranging counter values for one or
more STS segments. This allows estimation of individual clock offsets per subsystem in case different
subsystems are used to transmit or receive different STS segments, e.g., in ranging nodes featuring antenna
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