ISO/IEC 24730-5:2010

Information technology — Real-time locating systems (RTLS) — Part 5: Chirp spread spectrum (CSS) at 2,4 GHz air interface

ISO/IEC 24730 defines air interface protocols and an application programming interface (API) for real-time locating systems (RTLS). ISO/IEC 24730-5:2010 defines an air interface protocol which utilizes chirp spread spectrum (CSS) at frequencies from 2,4 GHz to 2,483 GHz. This protocol supports bidirectional communication and two-way ranging between the readers and tags of an RTLS. The mandatory default mode ensures interoperability between tags and infrastructure from various manufacturers, while the availability of several options offers flexibility to the developer of the infrastructure to adapt the behaviour of the overall system to the specific needs of his application.

Technologies de l'information — Systèmes de localisation en temps réel (RTLS) — Partie 5: Spectre étalé de compression d'impulsions (CSS) à une interface d'air de 2,4 GHz

General Information

• Status: Published
• Publication Date: 14-Mar-2010
• ICS: 35.040 - Information coding
• ICS: 35.040.50 - Automatic identification and data capture techniques
• Technical Committee: ISO/IEC JTC 1/SC 31 - Automatic identification and data capture techniques
• Drafting Committee: ISO/IEC JTC 1/SC 31/WG 4 - Radio communications
• Current Stage: 9093 - International Standard confirmed
• Start Date: 15-Dec-2022
• Completion Date: 14-Feb-2026

Overview

ISO/IEC 24730-5:2010 specifies an air interface for real-time locating systems (RTLS) using Chirp Spread Spectrum (CSS) in the 2.4 GHz ISM band (2.4 GHz to 2.483 GHz). Part 5 of the ISO/IEC 24730 family defines bidirectional communication and two‑way ranging between RTLS readers and tags, a mandatory default mode for multi‑vendor interoperability, plus optional behaviors developers can adopt to tailor system performance.

Keywords: ISO/IEC 24730-5, RTLS, chirp spread spectrum, CSS, 2.4 GHz, air interface, two-way ranging, interoperability.

Key Topics

• Frequency and PHY requirements: Defines the 2.4 GHz spread‑spectrum air interface, transmit power spectral density (PSD) masks, and physical layer (PHY) parameters.
• Modulation modes: Specifies 2‑ary orthogonal CSS and DQPSK‑CSS modulation approaches and their PHY packet formats.
• Data framing and packet formats: Details preamble, start‑of‑frame delimiter, PHY header, MAC frame types (Data, ACK, Broadcast, RTS/CTS), and general packet structure.
• MAC sub‑layer and timing: Covers MAC timing, media access, and handshake procedures (2‑way and 3‑way), essential for reliable communication and ranging.
• Ranging and application layer: Describes two‑way ranging packet exchanges, tag application states (default, wait, range, sleep, blink), commands, and default profiles for tagging behavior.
• Compliance and coexistence: Includes compliance requirements, time base tolerances for two‑way ranging, and coexistence guidance for operation in the 2.4 GHz band.
• Informative annexes: Guidance on computing location from range values, tag roaming, and coexistence considerations.

Applications and Who Uses It

ISO/IEC 24730-5 is intended for organizations designing, deploying, or integrating RTLS solutions that require robust indoor/outdoor position measurement and device interoperability:

• RTLS system integrators and solution architects implementing location services.
• Hardware manufacturers of CSS‑based readers and tags seeking compliance and cross‑vendor interoperability.
• Wireless and RF engineers implementing PHY and MAC layers for CSS at 2.4 GHz.
• Firmware and software developers building tag application logic, APIs, and ranging algorithms.
• Facility managers and asset‑tracking teams selecting technologies for inventory, personnel safety, or process optimization.

Practical benefits include reliable two‑way ranging, resistance to interference inherent in CSS, and a standardized framework that enables multi‑vendor ecosystems.

Related Standards

• Other parts of the ISO/IEC 24730 RTLS series (defining additional air interfaces and the RTLS API).
• Regulatory and coexistence standards for operation in the 2.4 GHz ISM band (local radio regulations should be consulted when implementing).

For implementers, ISO/IEC 24730-5 provides a clear blueprint to build interoperable, CSS‑based RTLS solutions at 2.4 GHz while supporting precise ranging and flexible system behavior.

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 24730-5
First edition
2010-04-01
Information technology — Real-time
locating systems (RTLS) —
Part 5:
Chirp spread spectrum (CSS) at 2,4 GHz
air interface
Technologies de l'information — Systèmes de localisation en temps réel
(RTLS) —
Partie 5: Spectre étalé de compression d'impulsions (CSS) à une
interface d'air de 2,4 GHz
Reference number
©
ISO/IEC 2010
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ii © ISO/IEC 2010 – All rights reserved

Contents Page
Foreword .vi
Introduction.vii
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Symbols and abbreviated terms .3
5 Overview.6
5.1 Components.6
5.2 Purpose .6
5.3 Not covered by the standard.7
5.4 System.7
5.5 Document structure .7
6 Requirements.7
6.1 Frequency range.7
6.2 2,4 GHz spread spectrum air interface specifications.7
6.3 Compliance requirements .8
6.4 Manufacturer tag ID.8
6.5 Physical layer parameters .8
7 Physical (PHY) layer specification.9
7.1 Modulations .9
7.2 Data rates .9
7.2.1 General PHY packet format .9
7.3 2-ary orthogonal CSS.9
7.3.1 Reference modulator diagram .10
7.3.2 Bandwidths and Transmit power spectral density (PSD) mask .10
7.3.3 Equivalent baseband representation of the continuous time 2-ary orthogonal CSS signal .12
7.3.4 Signal tolerance.13
7.3.5 Bit to symbol mapping.13
7.3.6 Chirp generator.13
7.3.7 Preamble.13
7.3.8 Start of frame delimiter .14
7.3.9 Bit scrambler.14
7.3.10 PHY Header .14
7.3.11 Overview (informative).14
7.4 DQPSK-CSS .16
7.4.1 Reference modulator diagram .16
7.4.2 Bandwidth and transmit Power Spectral Density (PSD) mask .17
7.4.3 Equivalent baseband representation of the continuous time DQPSK-CSS signal.18
7.4.4 Signal tolerance.20
7.4.5 Overview (informative).20
7.4.6 Demultiplexer (DEMUX) .22
7.4.7 Serial to Parallel mapping (S/P) .22
7.4.8 Data Symbol - to - Bi-Orthogonal code word mapping .22
7.4.9 Parallel - to - Serial converter (P/S) and QPSK symbol mapping.25
7.4.10 Differential-QPSK (DQPSK) coding .25
7.4.11 DQPSK to DQPSK-CSS modulation .26
7.4.12 Chirp generator.26
7.4.13 Bit interleaver.26
© ISO/IEC 2010 – All rights reserved iii

7.4.14 Preamble.26
7.4.15 Start of frame delimiter .27
7.4.16 PHY Header .27
8 MAC sub-layer specification.27
8.1 Overview.27
8.2 General packet format.27
8.3 Packet types.27
8.4 MAC frame formats.28
8.4.1 MAC frame format for Data packet.28
8.4.2 MAC frame format for ACK packet.28
8.4.3 MAC frame format for Broadcast packet.28
8.4.4 MAC frame format for RTS packet .29
8.4.5 MAC frame format for CTS packet .29
8.4.6 MAC frame fields.29
8.5 MAC Timing.31
8.5.1 2-way handshake .31
8.5.2 3-way handshake .32
8.5.3 Ranging-related time measurements.33
8.5.4 Media access.33
9 Tag application layer specification.36
9.1 Overview.36
9.1.1 Example scenario .37
9.2 Tag application states .38
9.2.1 Default state .38
9.2.2 Wait state .38
9.2.3 Range state.39
9.2.4 Sleep state .39
9.2.5 Blink state.39
9.2.6 State transitions.40
9.3 Commands .41
9.3.1 SwitchState command .42
9.3.2 SetConfigVector command.45
9.3.3 GetConfigVector command .47
9.3.4 SetRangingPeers command.47
9.3.5 AddRangingPeers command.47
9.3.6 GetRangingPeers command.48
9.3.7 User defined command .48
9.3.8 Command prioritization .48
9.4 Tag application packet formats.49
9.4.1 Application blink packet .50
9.4.2 Application command packet.51
9.4.3 Application report packet .51
9.4.4 GetConfigVector report.52
9.4.5 GetRangingPeers report .52
9.4.6 Ranging report .52
9.4.7 Application ranging packet.53
9.5 Ranging packet exchanges .57
9.5.1 Ranging packet exchange type 1.57
9.5.2 Ranging packet exchange type 2.58
9.5.3 Ranging packet exchange type 3.60
9.5.4 Ranging packet exchange type 4.61
9.6 Timing values.62
9.7 Default profile.62
9.8 Error handling .62
Annex A (informative) Time base tolerances in two-way ranging.63
Annex B (informative) Coexistence.66
Annex C (informative) Computing location values from range values.69
iv © ISO/IEC 2010 – All rights reserved

Annex D (informative) Location and roaming of tags .70
Bibliography.72
© ISO/IEC 2010 – All rights reserved v

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 24730-5 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 31, Automatic identification and data capture techniques.
ISO/IEC 24730 consists of the following parts, under the general title Information technology — Real-time
locating systems (RTLS):
⎯ Part 1: Application program interface (API)
⎯ Part 2: 2,4 GHz air interface protocol
⎯ Part 5: Chirp spread spectrum at 2,4 GHz air interface
vi © ISO/IEC 2010 – All rights reserved

Introduction
CSS is a technique for spreading the bandwidth of a digital signal by using chirp pulses. Chirp pulses are
pulses with a monotonically increasing or decreasing instantaneous frequency. Chirp pulses were originally
used for radar applications. Recently, systems and standards have been developed which use chirp pulses
also for communication applications. This part of ISO/IEC 24730 includes ranging and bidirectional
communication between tags and infrastructure. Bidirectional communication enables the infrastructure to
control the behaviour of tags in a timely manner.
© ISO/IEC 2010 – All rights reserved vii

INTERNATIONAL STANDARD ISO/IEC 24730-5:2010(E)

Information technology — Real-time locating systems (RTLS) —
Part 5:
Chirp spread spectrum (CSS) at 2,4 GHz air interface
1 Scope
ISO/IEC 24730 defines air interface protocols and an application programming interface (API) for real-time
locating systems (RTLS). This part of ISO/IEC 24730 defines an air interface protocol which utilizes chirp
spread spectrum (CSS) at frequencies from 2,4 GHz to 2,483 GHz. This protocol supports bidirectional
communication and two-way ranging between the readers and tags of an RTLS. The mandatory default mode
ensures interoperability between tags and infrastructure from various manufacturers, while the availability of
several options offers flexibility to the developer of the infrastructure to adapt the behaviour of the overall
system to the specific needs of his application.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 15963, Information technology — Radio frequency identification for item management — Unique
identification for RF tags
ISO/IEC 19762-1, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 1: General terms relating to AIDC
ISO/IEC 19762-3, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 3: Radio frequency identification (RFID)
ISO/IEC 19762-4, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 4: General terms relating to radio communications
ISO/IEC 19762-5, Information technology — Automatic identification and data capture (AIDC) techniques —
Harmonized vocabulary — Part 5: Locating systems
ISO/IEC 24730-1, Information technology — Real-time locating systems (RTLS) — Part 1: Application
program interface (API)
Guidelines on Limiting Exposure to Non-Ionizing Radiation, International Commission on Non-Ionizing
Radiation Protection (ICNIRP), Munich, 1999
IEC 62369-1 ed1.0, Evaluation of human exposure to electromagnetic fields from short range devices (SRDs)
in various applications over the frequency range 0 GHz to 300 GHz — Part 1: Fields produced by devices
used for electronic article surveillance, radio frequency identification and similar systems
IEEE Std C95.1-2005, IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency
Electromagnetic Fields, 3 kHz to 300 GHz
© ISO/IEC 2010 – All rights reserved 1

3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19762-1, ISO/IEC 19762-3,
ISO/IEC 19762-4, ISO/IEC 19762-5 and the following apply.
3.1
chirp spread spectrum
technique for spreading the bandwidth of a digital signal using linear frequency sweep signals
3.2
Class I
system that operates at a radiated power of up to 10 mW EIRP
3.3
Class II
system that operates at a radiated power higher than 10 mW up to the maximum defined by local regulations
3.4
ranging
process of determining the distance between two RTLS transceivers through the exchange of a specific set of
messages
3.5
ranging peer
RTLS transceiver with which to perform ranging
3.6
RF channel
combination of a centre frequency value and bandwidth value
3.7
RTLS tag
RTLS transceiver that accepts commands from RTLS readers and sends blinks and/or reports to the RTLS
readers
3.8
RTLS transmitter
part of an RTLS transceiver which is capable of sending messages
3.9
demultiplexer
equipment for reversing the process of multiplexing
3.10
medium
wireless channel
3.11
trilateration
method of determining the relative positions of objects using the known locations of three reference points and
the measured distance between the object to be located and each reference point
3.12
interleaving
rearrangement or transposition of data to enhance the effectiveness of error control schemes
3.13
interleaver
unit that performs interleaving (3.12)
2 © ISO/IEC 2010 – All rights reserved

3.14
baseband
frequency band occupied by the aggregate of the signals used to modulate a carrier before they combine with
the carrier in the modulation process
3.15
orthogonal
inner product being close to zero
3.16
peer X
x'th peer in a description of a situation with multiple peers
4 Symbols and abbreviated terms
ACK acknowledge
ARQ Automatic Repeat Query
BTS Backoff Time Slot
CIFS Carrier sense Inter Frame Space
CTS Clear To Send
CRC Cyclic Redundancy Check
CSMA/CA Carrier Sense Multiple Access / Collision Avoidance
CSS Chirp Spread Spectrum
dBr decibel relative
DEMUX demultiplexer
DQPSK Differential Quadrature Phase Shift Keying
DQPSK-CSS Differential Quadrature Phase Shift Keying over Chirp Spread Spectrum
Dst Destination address
EIRP Equivalent Isotropical Radiated Power
LFSR Linear Feedback Shift Register
LSB Least Significant Bit
MMSE Minimum Mean Square Error
MAC Medium Access Control
NAV Network Allocation Vector
PHR PHY header
PHY physical layer
PPDU PHY Protocol Data Unit
© ISO/IEC 2010 – All rights reserved 3

PSDU PHY Service Data Unit
QPSK Quadrature Phase Shift Keying
RTS Request To Send
RTLS Real Time Locating System
SFD Start of Frame Delimiter
SHR synchronization header
SIFS Short Inter Frame Space
Src source address
TWR Two Way Ranging
SDS-TWR Symmetric Double Sided Two Way Ranging
e Euler constant
j imaginary unit
M
~
s (t) continuous time baseband representation of 2-ary orthogonal CSS signal
M M
~ ~
0 0
r (t) implemented version of s (t)

M
~
s (t) continuous time baseband representation of DQPSK-CSS signal
m
M M
~ ~
1 1
r (t) implemented version of s (t)
m m
m configuration constant determining the type (one our of four possibilities) of sub-chirp
sequence used
M superscript indicating that 2-ary orthogonal CSS is described
M superscript indicating that DQPSK-CSS is described
k index variable
n index variable
b n'th symbol to be transmitted
n
c (t) continuous time baseband representation of chirp pulse b for 2-ary orthogonal CSS
b
µ configuration constant determining the chirp rate for 2-ary orthogonal CSS
µ constant determining the chirp rate for DQPSK-CSS
T timebase
base
4 © ISO/IEC 2010 – All rights reserved

T time in between two sub blinks
SBIFS
T average blink repetition time
Blink
T random time
Rand
T duration of time interval for during which the receiver of a tag is activated
Rxon
T maximum expected duration between a tag receiving any packets from infrastructure if such
Contact
is present
T duration of time interval during which a tag application shall respond to certain requests
TimeoutApplication
T duration of time for which a tag shall go to Wait state after leaving Range state
WaitAfterRange
T configuration constant determining the duration of a chirp pulse for 2-ary orthogonal CSS
T duration of sub-chirp sequence
T duration of sub-chirp
sub
T time position of k'th sub-chirp of n'th sub-chirp sequence of type m
n,k ,m
W (t) raised cosine window of duration T
T
α roll of factor of the raised cosine window
A amplitude variable which is minimized in minimum mean square error computation
τ time delay variable that is minimized in minimum mean square error computation
d
φ phase variable that is minimized in minimum mean square error computation
d information sample of k'th sub-chirp in n'th sub-chirp sequence
n,k
sub
C (t) continuous time baseband representation of k' sub-chirp of sub-chirp sequence type m
k,m
τ timing constant that determines the time-gap between subsequent sub-chirp sequences for
m
the sub-chirp sequence type m
f offset centre frequency of k'th sub-chirp in sub-chirp sequence type m
k,m
ζ chirp direction of k'th sub-chirp in sub-chirp sequence type m
k ,m
sub
S (t) continuous time baseband representation of sub-chirp sequence of type m
m
© ISO/IEC 2010 – All rights reserved 5

5 Overview
5.1 Components
The major components of a real-time locating system (RTLS) and the relationship of those components are
shown in Figure 1. As shown in this Figure the tags communicate with an infrastructure. The infrastructure
provides an application program interface (API) through which an application can control the RTLS and
retrieve information about location and state of tags.
TaTagg
IInnffrrastrastrucucttuurree
APIAPI
TaTagg
TagTag
((IISOSO/IE/IEC 24730C 24730--11))
BidBidiirreeccttional airional air inter interffaceace
((TThis parhis part ot off IS ISOO/IEC 24/IEC 24730730))
DeveloDeveloperper s specpeciifficic

Figure 1 – RTLS components
As indicated in Figure 1 tags communicate with infrastructure over an air interface. Generally the air interface
includes the definition of waveforms, formats of packets as well as commands and reports to be exchanged
between tags and infrastructure. This can be depicted in a layered approach as shown in Figure 2. Similar
[1]
interpretations can be found in other standards e.g. in ISO/IEC 18000-1 .
TTaag apg applicaplicattiioonn llaayyeerr
MAMACC la layyeerr
TagTag InInffrraasstrtructuctuurree
PPhhysysiiccaall la layeyerr
Figure 2 – Air interface layers
5.2 Purpose
This part of ISO/IEC 24730 defines an air interface protocol that optimizes small scale RTLS with an
installation that enables simple, and also handheld, RTLS readers. Although the infrastructure itself is not
defined in this part of ISO/IEC 24730, it is anticipated that the air interface protocol has a strong impact on the
realization of the infrastructure and the related installation effort.
The key condition for simple installation is the possibility of ’autonomous’ infrastructure nodes. In this part of
ISO/IEC 24730, “autonomous” means there is not a requirement for these nodes to be synchronized with
other infrastructure nodes. After being placed at a fixed location, an autonomous node simply responds to
requests from RTLS tags.
This condition is achieved by specifying bidirectional communication and two-way ranging. As a consequence,
the tag must also support bidirectional communication. Although this requirement increases the complexity of
6 © ISO/IEC 2010 – All rights reserved

the tag in one area, it also decreases the complexity in other areas, as additional interfaces for programming
and conditioning the tag are not required. Thus bidirectional communication with the tag is seen as beneficial
for many applications. Finally in order to utilize existing state of the art communication technology this part of
[5]
ISO/IEC 24730 includes parts that correspond with IEEE 802.15.4a , which is a PHY amendment of IEEE
[4]
802.15.4 , a successful standard for low power, low data rate wireless communication.
5.3 Not covered by the standard
The design of the infrastructure is left completely to the developer, e.g. the density of RTLS reader nodes,
how the RTLS readers are controlled and communicate with each other, how the infrastructure is set up, etc.
may be different in various scenarios and for systems from different vendors. For typical RTLS applications, at
least three RTLS readers will communicate with each tag, measuring time of flight in order to locate the tag.
For more details on this interaction, see Clause 9, Tag application layer specification.
5.4 System
After power on, a tag uses a default profile in which it blinks periodically. With each blink the tag signals its
physical address, its capabilities and information about when it will be ready to receive commands from the
infrastructure.
The infrastructure decides whether it needs to send commands to the tag while the tag is listening. By sending
commands to the tag, the infrastructure controls which RTLS readers are part of the infrastructure the tag
performs ranging with. Furthermore the infrastructure can adapt the behaviour of the tags to the actual
conditions such as the number of tags in range, number of infrastructure nodes available, etc. For example,
the infrastructure is able to instruct the tag to change to another mode (bandwidth, centre frequency, data
rate) according to the actual environment or to perform ranging with a specific set of RTLS readers.
When the tag assumes that it has lost connection to the infrastructure e.g. because it doesn’t receive any
commands for a certain time, it reverts to the default profile. A more detailed description of complete system
behaviour can be found in Annex D.
5.5 Document structure
The remainder of this part of ISO/IEC 24730 follows the "layered structure" mentioned above. This means that
after the Requirements clause the three layers that form an air interface protocol (the Physical Layer [PHY],
Media Access Control [MAC] and the Tag application layer) are addressed and specified separately.
Additional information for the user of this part of ISO/IEC 24730 is provided in the informative annexes.
6 Requirements
6.1 Frequency range
This part of ISO/IEC 24730 addresses real-time locating systems (RTLS) operating in the 2,400 to
2,4835 GHz frequencies.
6.2 2,4 GHz spread spectrum air interface specifications
The minimum requirements shall include:
– RTLS transceivers shall autonomously generate a chirp spread spectrum frequency beacon indicating
when the receiver will be activated.

– RTLS transceivers shall be able to perform two-way ranging when the receiver is activated.

– RTLS transmitters shall be fully compliant with local regulatory requirements.

© ISO/IEC 2010 – All rights reserved 7

– Class I RF transmissions shall not exceed 10 mW EIRP

– Class II RF transmissions shall not exceed 100 mW EIRP or the maximum EIRP according to the
local radio regulations.
6.3 Compliance requirements
To be fully compliant with this part of ISO/IEC 24730, real-time locating systems (RTLS) shall also comply with
ISO/IEC 24730-1.
Device manufacturers claiming conformance to this part of ISO/IEC 24730 shall self-certify RF emissions do
not exceed the maximum permitted exposure limits recommended by either IEEE C95.1: 2005 or ICNIRP
according to IEC 62369-1. If a device manufacturer is unsure as to which recommendation to be cited for
compliance the manufacturer shall self-certify to ICNIRP limits.
6.4 Manufacturer tag ID
The manufacturer’s tag identification number identifies a particular manufacturer and consists of 16 bits. A
manufacturer may have more than one ID number. The frame format used in this part of ISO/IEC 24730
mandates a MAC address of at least 48 bits for each device. The first 16 bits of the MAC address are
designated for the manufacturer’s identification number and shall be assigned according to ISO/IEC 15963
Annex D, under Allocation Class 0000 0000.
6.5 Physical layer parameters
For the purposes of this part of ISO/IEC 24730, the following parameter definitions apply in Table 1. These
parameters are referenced by parameter name. These operating parameters are to be defined for the
temperature range of minus 30 degrees Celsius to 50 degrees Celsius.
Table 1 – 2,4 GHz CSS link parameters
Parameter name Description
As permitted by local radio regulations in the band from
Operating frequency range
2400 to 2483,5 MHz.
Operating frequency accuracy ± 70 ppm (2-ary orthogonal CSS)
± 40 ppm (DQPSK –CSS)
Maximum phase noise -85 dBc/Hz @ 1 MHz
Occupied 20 dB channel bandwidth 80 MHz (Default value)
22 MHz (Configuration option)
Centre frequency, bandwidth combination According to Table 2 and Table 6
Time base, T 31,25 ns
base
Time base accuracy ± 40 ppm
Transmit power Class 1: 10 dBm EIRP. max.
Class 2: Maximum in accordance to local regulations.
Transmitter spectrum mask According to Table 3 and Figure 13
Spurious emission, out of band The device shall transmit in conformance with spurious
emissions requirements defined by the country’s
regulatory authority within which the system is
operated.
Modulation 2-ary orthogonal CSS
DQPSK-CSS (optional)
8 © ISO/IEC 2010 – All rights reserved

Parameter name Description
Data bit rates 1 Mbit/s
250 kbit/s
Symbol rates 10 symbols/s,
250000 symbols/s
166667 symbols/s (with DQPSK-CSS)
7 Physical (PHY) layer specification
7.1 Modulations
The PHY layer specification shall contain two modulations (2-ary orthogonal CSS and DQPSK-CSS). The
support of 2-ary orthogonal shall be mandatory while the support of DQPSK-CSS is optional.
7.2 Data rates
2-ary orthogonal CSS shall support data rates of 1 Mbits/s and 250 kbit/s.
DQPSK-CSS, when implemented, shall support data rates of 1 Mbits/s and 250 kbit/s.
7.2.1 General PHY packet format
A PHY packet shall consist of a synchronization header and a PHY protocol data unit as shown in Figure 3.
SSyynchrnchronionizzatation ion headerheader ( (SSHRHR)) PPHHYY prprototococol datol data unita unit ( (PPPPDDU)U)
PrPreameambleble StStarartt ofof f frraamme delime delimititerer ((SSFDFD))
PHPHYY header header ((PPHRHR)) PHPHYY prprototococol sol seerrvvicice unite unit ( (PSDPSDU)U)

Figure 3 – General PHY packet structure
The definitions of preamble, SFD and PHY are given in 7.3.7, 7.3.8, 7.3.10 and 7.4.14, 7.4.15, 7.4.16.
The PSDU shall contain the MAC a frame defined Clause 8.
7.3 2-ary orthogonal CSS
2-ary orthogonal CSS shall be the mandatory PHY mode. A combination of centre frequency and bandwidth
shall called "RF channel". The possible RF channels are defined in Table 2.
© ISO/IEC 2010 – All rights reserved 9

Table 2 – Possible combinations of centre frequency and bandwidth for 2-ary orthogonal CSS
RF channel number Centre frequency Bandwidth
0 2441,75 MHz 80 MHz
1 2441,75 MHz 22 MHz
2 2412 MHz 22 MHz
3 2417 MHz 22 MHz
4 2422 MHz 22 MHz
5 2427 MHz 22 MHz
6 2432 MHz 22 MHz
7 2437 MHz 22 MHz
8 2442 MHz 22 MHz
9 2447 MHz 22 MHz
10 2452 MHz 22 MHz
11 2457 MHz 22 MHz
12 2462 MHz 22 MHz
13 2467 MHz 22 MHz
14 2472 MHz 22 MHz
15 2484 MHz 22 MHz
7.3.1 Reference modulator diagram
The functional block diagram in Figure 4 is provided as a reference for specifying 2-ary orthogonal CSS for
both data rates 1 Mbits/s and 250 kbit/s. The functionality of the Bit scrambler block is specified in 7.3.9. The
functionality of the Bit to symbol mapping block is specified in 7.3.5. The functionality of the chirp generator
block is specified in 7.3.6.
BiBit t
PSPSDUDU
scscrraambmblleerr BBiit tt too s syymmbbooll ChiChirrpp
mmaappingpping generatgeneratoror
PPrreameamble,ble, S SFFDD,, PPHHRR

Figure 4 – Reference modulator for 2-ary orthogonal CSS
7.3.2 Bandwidths and Transmit power spectral density (PSD) mask
The supported bandwidth values shall be 80 MHz and 22 MHz. The transmitted spectral products shall be less
than the limits specified in Table 3, Figure 5 and Figure 6. For both relative and absolute limits, average
spectral power shall be measured using a 100 kHz resolution bandwidth. For the relative limit, the reference
level shall be the highest average spectral power measured within ± Bandwith/2 of the centre frequency, fc.
For testing the transmitted spectral power density a pseudo-random binary sequence shall be used as input
data.
10 © ISO/IEC 2010 – All rights reserved

Table 3 – Transmit PSD limits for 2-ary CSS
Frequency Relative limit Absolute limit
|f-fc| >Bandwith/2 -20 dBr -30 dBm

dBrdBr
-1-100
-2-200
-3-300
[M[MHHzz]] of offfsset froet fromm
cceentrntree f frreqequuencencyy
--41,741,755 00 4141,,7755
Figure 5 – Transmit PSD limits for 2-ary orthogonal CSS at 80 MHz bandwidth
[d[dBr]Br]
-10-10
-20-20
-30-30
[M[MHHzz]] o offsffseett fr froomm
centcentre fre frreqequueencyncy
-11-11 00 1111
Figure 6 – Transmit PSD limits for 2-ary orthogonal CSS at 22 MHz bandwidth
© ISO/IEC 2010 – All rights reserved 11

7.3.3 Equivalent baseband representation of the continuous time 2-ary orthogonal CSS signal
M
~
The mathematical representation of the continuous time-domain baseband signal s (t) for 2-ary orthogonal
CSS shall be given by Equation (1).
∞
T
⎛ ⎞
M
~ 0
s (t) = c t −nT −
⎜ ⎟ (1)
∑ b 0
n
n=0 ⎝ ⎠
Where
M is indicating that 2-ary orthogonal CSS is described,
n is the index of the symbol,
b are symbols to be transmitted, which can take the values from [1, -1] and determine which of the two
n
possible pulses is actually realized.
c (t) are the continuous time-domain baseband versions of the two possible pulses, which are required for
b
2-ary orthogonal modulation and which shall be chirp pulses as described by Equation (2).
⎧ µ T
⎡ ⎤
0 2 0
exp j ⋅b ⋅ ⋅t ⋅W (t) for |t |≤
⎪ T
⎢ ⎥
2 2
⎣ ⎦
⎪
c (t) =
(2)
⎨
b
⎪
0 otherwise
⎪
⎩
Where
80MHz 22MHz
µ is a constant which either takes the value 2π ⋅ or 2π ⋅ depending on the bandwidth
T T
0 0
selected.
T is the duration of the chirp pulse which can take a value of 1 µs or 4 µs, depending on the data rate,
j = −1
and
W (t) is the raised cosine window as described in Equation (3).
T
12 © ISO/IEC 2010 – All rights reserved

()1−α T
⎧
1 for |t |≤
⎪
()1+ α 2
⎪
⎡ ⎤
⎛ ⎞
1 ()1+ α π⎛ ()1−α T⎞ ()1−α T T
⎪
⎜ ⎟
W (t) = 1+ cos ⎜|t | − ⎟ for <|t |≤
⎨ ⎢ ⎥
T
⎜ ⎟
⎜ ⎟
2 αT ()1+ α 2 ()1+ α 2 2
(3)
⎢ ⎝ ⎠⎥
⎪ ⎝ ⎠
⎣ ⎦
⎪
T
0 for |t |>
⎪
⎩
with α = 0.25
Where
T is the duration of the raised cosine window.
α is the roll off factor of the raised cosine window.
7.3.4 Signal tolerance
In addition to the limits specified in Table 3, the Minimum Mean Square Error, MMSE, shall be used as
M M
~ ~
0 0
criterion for the compliance of the signal. Let s (t) be the signal that is defined by (1). Then r (t) , the
M
~
implemented version of s (t) , shall satisfy (4) for b =+1 and b =-1.
0 0
T
⎡ ⎤
M M
~ ~ jϕ
0 0
s (t) − A ⋅r (t −τ ) ⋅e dt
⎢ ⎥
d
∫
⎢ 0 ⎥
MMSE = ≤ 0.005
(4)
min T
⎢ ⎥
A,τ ,ϕ
d M
~
⎢ ⎥
s (t) dt
∫
⎢ ⎥
⎣ 0 ⎦
where the variables A, τ , and φ are used to minimize the mean squared error.
d
7.3.5 Bit to symbol mapping
A bit value of 0 shall be mapped to b=-1.
A bit value of 1 shall be mapped to b=1.
7.3.6 Chirp generator
The chirp generator shall generate subsequent pulses as defined in Equation (2).
7.3.7 Preamble
The preamble for 2-ary orthogonal CSS shall consist of 30 alternating bits starting with bit 0 as shown in
Table 4.
Table 4 – Preamble bit sequence for 2-ary orthogonal CSS
Bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15 17 18 19 20 21 22 23 24 25 26 27 28 29
1 0 1 0 1 0 1 0 1 0 1 0101 0101 010 1 0 1 01 01 0

© ISO/IEC 2010 – All rights reserved 13

7.3.8 Start of frame delimiter
The start of frame delimiter (SFD) for 2-ary orthogonal CSS shall consist of 64 bits that cor
...