ISO/IEC 14543-3-10:2012

ISO/IEC 14543-3-10
Edition 1.0 2012-03
INTERNATIONAL
STANDARD
colour
inside
Information technology – Home electronic system (HES) architecture –
Part 3-10: Wireless short packet (WSP) protocol optimised for energy
harvesting – Architecture and lower layer protocols

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ISO/IEC 14543-3-10
Edition 1.0 2012-03
INTERNATIONAL
STANDARD
colour
inside
Information technology – Home electronic system (HES) architecture –

Part 3-10: Wireless short packet (WSP) protocol optimised for energy

harvesting – Architecture and lower layer protocols

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.240.67 ISBN 978-2-8891-2970-6

– 2 – 14543-3-10 © ISO/IEC:2012(E)

CONTENTS
FOREWORD. 4

INTRODUCTION . 6

1 Scope . 7

2 Normative references . 7

3 Terms, definitions and abbreviations . 8

3.1 Terms and definitions . 8

3.2 Abbreviations . 12

4 Conformance . 12
5 Architecture . 12
5.1 Generic protocol description . 12
5.1.1 Overview . 12
5.1.2 Physical layer . 13
5.1.3 Data link layer . 13
5.1.4 Network layer . 13
5.1.5 Transport layer . 14
5.1.6 Session layer . 14
5.1.7 Presentation layer . 14
5.1.8 Application layer . 14
5.2 Data unit description . 14
6 Layer 1 – Physical layer . 15
6.1 Overview . 15
6.2 General description . 15
6.3 Requirements for the 315 MHz WSP protocol . 18
6.4 Requirements for the 868,3 MHz WSP protocol . 20
6.5 Frame Structure . 22
7 Layer 2 – Data link layer . 23
7.1 Overview . 23
7.2 Subtelegram timing . 23
7.3 Data integrity . 25
7.3.1 General . 25
7.3.2 4 bit summation hash function algorithm . 25
7.3.3 8 bit summation hash function algorithm . 25

7.3.4 8 bit Cyclic Redundancy Check (CRC) hash function algorithm . 26
7.4 Listen before talk . 26
8 Layer 3 – Network layer . 26
8.1 Overview . 26
8.2 Switch telegram . 27
8.3 Repeater . 28
8.3.1 General . 28
8.3.2 Time response for collision avoidance . 28
8.3.3 Bits of a repeater level in the STATUS byte . 28
8.4 Addressing . 29
8.4.1 General . 29
8.4.2 Encapsulation . 29
Annex A (informative) Examples of how to evaluate the hash values . 31

14543-3-10 © ISO/IEC:2012(E) – 3 –

Bibliography . 33

Figure 1 – Structure of a subtelegram . 14

Figure 2 – Illustration of an ASK envelope and various physical parameters . 16

Figure 3 – Complete frame structure for the 868,3 MHz WSP protocol . 22

Figure 4 – Encoded subframe . 22

Figure 5 – TX maturity time divided into four 10 ms time ranges . 24

Figure 6 – Conversion of a switch telegram to a normal telegram . 28

Figure 7 – Example of an encapsulation . 30
Figure A.1 – Example of a C code program of the 4 bit long summation hash value . 31
Figure A.2 – Example of a C code program of the 8 bit long summation hash value . 31
Figure A.3 – Efficient C code program for the evaluation of an 8 bit long CRC type
hash value . 32

Table 1 – WSP protocol stack structure (OSI) . 13
Table 2 – Transmitter requirements for the 315 MHz WSP protocol . 18
Table 3 – Receiver requirements for the 315 MHz WSP protocol . 19
Table 4 – Minimum required link budget for the 315 MHz WSP protocol . 19
Table 5 – Maximum RX power for the 315 MHz WSP protocol . 19
Table 6 – Transmitter requirements for the 868,3 MHz WSP protocol . 20
Table 7 – Receiver requirements for the 868,3 MHz WSP protocol . 21
Table 8 – Minimum required link budget for the 868,3 MHz WSP protocol . 21
Table 9 – Maximum RX power for the 868,3 MHz WSP protocol . 21
Table 10 – Frame definition for the 315 MHz WSP protocol . 23
Table 11 – Frame definition for the 868,3 MHz WSP protocol . 23
Table 12 – Maturity time parameters . 24
Table 13 – Allocation of time slots to the different subtelegrams . 24
Table 14 – Identification of the hash function used in the telegram . 25
Table 15 – Conversion of the telegram type and STATUS fields from a switch telegram
to a telegram . 27
Table 16 – STATUS byte with repeater level bits . 29
Table 17 – Repeating bits in STATUS byte . 29

– 4 – 14543-3-10 © ISO/IEC:2012(E)

INFORMATION TECHNOLOGY –
HOME ELECTRONIC SYSTEM (HES) ARCHITECTURE –

Part 3-10: Wireless short-packet (WSP)

protocol optimised for energy harvesting –

Architecture and lower layer protocols

FOREWORD
1) ISO (International Organization for Standardization) and IEC (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. Their preparation is entrusted to technical committees; any ISO and
IEC member body interested in the subject dealt with may participate in this preparatory work. International
governmental and non-governmental organizations liaising with ISO and IEC also participate in this preparation.
2) In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
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.
3) The formal decisions or agreements of IEC and ISO on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested IEC and ISO member bodies.
4) IEC, ISO and ISO/IEC publications have the form of recommendations for international use and are accepted
by IEC and ISO member bodies in that sense. While all reasonable efforts are made to ensure that the
technical content of IEC, ISO and ISO/IEC publications is accurate, IEC or ISO cannot be held responsible for
the way in which they are used or for any misinterpretation by any end user.
5) In order to promote international uniformity, IEC and ISO member bodies undertake to apply IEC, ISO and
ISO/IEC publications transparently to the maximum extent possible in their national and regional publications.
Any divergence between any ISO/IEC publication and the corresponding national or regional publication
should be clearly indicated in the latter.
6) ISO and IEC provide no marking procedure to indicate their approval and cannot be rendered responsible for
any equipment declared to be in conformity with an ISO/IEC publication.
7) All users should ensure that they have the latest edition of this publication.
8) No liability shall attach to IEC or ISO or its directors, employees, servants or agents including individual experts
and members of their technical committees and IEC or ISO member bodies for any personal injury, property
damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees)
and expenses arising out of the publication of, use of, or reliance upon, this ISO/IEC publication or any other IEC,
ISO or ISO/IEC publications.
9) Attention is drawn to the normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.

10) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
The International Standard ISO/IEC 14543-3-10 was prepared by subcommittee 25:
Interconnection of information technology equipment, of ISO/IEC joint technical committee 1:
Information technology.
The list of all currently available parts of the ISO/IEC 14543 series, under the general title
Information technology – Home electronic system (HES) architecture, can be found on the
IEC web site.
This International Standard has been approved by vote of the member bodies, and the voting
results may be obtained from the address given on the title page.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

14543-3-10 © ISO/IEC:2012(E) – 5 –

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – 14543-3-10 © ISO/IEC:2012(E)

INTRODUCTION
Various electrically controlled sensors and switches are used in homes and similar

environments for many different applications. Examples of such applications are lighting,

heating, energy management, blinds control, different forms of security control and

entertainment (audio and video).

In most cases the device, e.g. a switch initiating an action, and the device, e.g., a lamp, are

installed at different places. The distance can be bridged by wires, infrared or radio

transmission. Presently equipment at both ends of a wireless transmission link needs to be

powered by line or battery.
While wireless transmissions are especially attractive to retrofit homes, power maintenance of
battery-driven devices is a burden. In addition, these batteries require scarce materials. Since
the command and control messages sent by control and sensor devices in homes are very
short, they can be powered using new techniques for energy harvesting, provided they use a
wireless protocol that operates on relatively low power. Energy available in the environment of
a device is captured and stored (harvested) to power operation of the device. Examples of
energy sources are mechanical actuation, solar radiation, temperature differences, etc. If this
is executed at least one device in the link neither needs a battery nor a wire. Energy
harvesting devices need very limited power and use an energy efficient radio protocol to send
data to other conventionally powered devices in the home. In order to ensure interoperability
of such devices from different sources within a home, an international standard for a protocol
is required that uses the little power that energy harvested devices can provide and at the
same time spans distances to be bridged within a home environment.
Several such devices used within a home may come from different sources. They are required
to interwork with each other using a common internal network (in this standard called a home
network) and supporting a home automation system. When a home automation system meets
ISO/IEC HES Standards, it is called a Home Electronic System (HES).
ISO/IEC 14543-3-10 specifies the Wireless Short-Packet protocol. The protocol is efficient
enough to
• support energy harvested products for sensors and switches that do not require wires and
batteries, and
• extend the life of battery-operated devices.

14543-3-10 © ISO/IEC:2012(E) – 7 –

INFORMATION TECHNOLOGY –
HOME ELECTRONIC SYSTEM (HES) ARCHITECTURE –

Part 3-10: Wireless short-packet (WSP)

protocol optimised for energy harvesting –

Architecture and lower layer protocols

1 Scope
This part of ISO/IEC 14543 specifies a wireless protocol for low-powered devices such as
energy harvested devices in a home environment. This wireless protocol is specifically
designed to keep the energy consumption of such sensors and switches extremely low.
The design is characterised by
• keeping the communications very short, infrequent and mostly unidirectional, and
• using communication frequencies that provide a good range even at low transmit power
and avoid collisions from disturbers.
This allows the use of small and low cost energy harvesters that can compete with similar
batteries-powered devices. The messages sent by energy harvested devices are received and
processed mainly by line-powered devices such as relay switch actuators, repeaters or
gateways. Together these form part of a home automation system, which, when conforming to
the ISO/IEC 14543 series of standards, is defined as a home electronic system.
This part of ISO/IEC 14543 specifies OSI Layers 1 to 3 of the Wireless Short-Packet (WSP)
protocol.
The WSP protocol system consists of two and optionally three types of components that are
specified in this standard. These are the transmitter, the receiver and optionally the repeater.
Repeaters are needed when the transmitter and the receiver are located in such a way that no
good direct communication between them can be established.
Protection against malicious attacks is handled in the upper layers and thus not treated in this
standard.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
ISO/IEC 7498-1, Information technology – Open systems interconnection – Basic reference
model – Part 1: The basic model
EN 300 220-1, Electromagnetic compatibility and Radio spectrum Matters (ERM); Short
Range Devices (SRD); Radio equipment to be used in the 25 MHz to 1 000 MHz frequency
range with power levels ranging up to 500 mW – Part 1: Technical characteristics and test
methods
– 8 – 14543-3-10 © ISO/IEC:2012(E)

3 Terms, definitions and abbreviations

3.1 Terms and definitions
For the purposes of this document the following terms and definitions apply.

3.1.1
amplitude shift keying envelope

ASK envelope
envelope of the modulated signal

3.1.2
bit duration
time between transitions of the mesial power level of an ASK envelope in an alternating
sequence
Note 1 to entry: Figure 2 shows this in detail.
3.1.3
bit duration error
deviation of bit duration from specified bit duration
3.1.4
byte
represented by 8 bits
3.1.5
collision
two wireless transmitters using the same wireless channel and transmitting data at the same
time
3.1.6
cyclic redundancy check
CRC
integrity hash algorithm based on a polynomial division
3.1.7
DATA
application payload data transmitted in the telegram
3.1.8
energy harvesting
energy available in the environment of a device that is captured and stored (harvested) to
power operation of the device
Note 1 to entry: Examples of energy sources are mechanical actuation, solar radiation, temperature differences,
etc.
3.1.9
frame
set of data to be transmitted as a complete unit on the physical layer
Note 1 to entry: A frame contains the necessary protocol control and synchronisation data for transmission
between network nodes.
14543-3-10 © ISO/IEC:2012(E) – 9 –

3.1.10
HASH
field in which the hash value for the data integrity control of each transmitted telegram and

subtelegram is specified
3.1.11
high nibble
upper 4 bits of the byte
Note 1 to entry: The N value from the byte 0xNM.

3.1.12
high state amplitude
power level of the high state level
3.1.13
high state level
level of the ASK envelope that represents the high state amplitude
Note 1 to entry: The definition aligns with IEEE 194-1977, 5.2.2.5, static levels. Figure 2 gives an illustration.
3.1.14
identity of the destination device
DESTID
unique identity of the destination device of a WSP telegram consisting of four bytes
3.1.15
identity of the transmitting device
TXID
unique identity of the WSP protocol transmitting device consisting of four bytes
3.1.16
inverse bits
INV
rd th
added by the encoding procedure into a subframe behind the 3 and the 6 bit to reduce the
DC content of the data
3.1.17
listen before talk
LBT
technique of checking the occupancy of the wireless channel before transmitting any frames

3.1.18
low nibble
lower 4 bits of the byte
Note 1 to entry: The M value from the byte 0xNM.
3.1.19
low state amplitude
power level of the low state level.
3.1.20
low state level
level of the ASK envelope that represents the low state amplitude
Note 1 to entry: The definition aligns with IEEE 194-1977, 5.2.2.5, static levels. Figure 2 gives an illustration.

– 10 – 14543-3-10 © ISO/IEC:2012(E)

3.1.21
mesial power level
median between high state level and low state level of an ASK envelope

Note 1 to entry: Figure 2 gives an illustration.

3.1.22
negative overshoot
difference between minimum peak level and low state level of an ASK envelope after a

transition from a high state to a low state has occurred

Note 1 to entry: Figure 2 gives an illustration.
3.1.23
negative undershoot
difference between maximum peak level and low state level of an ASK envelope after a
transition from a high state to a low state has occurred
Note 1 to entry: Figure 2 gives an illustration.
3.1.24
nibble
four-bit aggregation or half a byte
3.1.25
positive overshoot
difference between maximum peak level and high state level of ASK envelope after a
transition from a low state to a high state has occurred
Note 1 to entry: Figure 2 gives an illustration.
3.1.26
positive undershoot
difference between minimum peak level and high state level of ASK envelope after a transition
from a low state to a high state has occurred
Note 1 to entry: Figure 2 gives an illustration.
3.1.27
receiving device maturity time
determines at the receiving device the maximum time between the end of the first
subtelegram and the end of the last subtelegram belonging to the same telegram

3.1.28
repeated telegrams
telegrams transmitted by a repeater
3.1.29
repeater
receives telegrams and sends refreshed signals to any WSP receiver
3.1.30
subframe
subtelegram byte expanded by protocol control and synchronisation information

14543-3-10 © ISO/IEC:2012(E) – 11 –

3.1.31
subtelegram
smallest interpreted data unit containing the fields telegram type (RORG), payload (DATA),

transmitter identity (TXID), STATUS and HASH

3.1.32
switch telegram
telegram with fields telegram type (RORG), payload (DATA), transmitter identity (TXID) and

HASH
Note 1 to entry: The switch telegram structure differs from the telegram in that the fields of RORG and HASH are
only 4 bits long and that it does not contain a STATUS field.

3.1.33
synchronisation bits
SYNC
bits inserted by an encoding procedure at the end of each subframe (except for the last
subframe) to provide clock resynchronisation
Note 1 to entry: Synchronisation bits also reduce the DC content of transmitted data and can be used to ensure
data reliability and integrity.
3.1.34
telegram
data unit composed of one or more identical subtelegrams
Note 1 to entry: A telegram has the same structure and contains the same information as a subtelegram.
3.1.35
telegram type
RORG
identifies the type of a telegram in the WSP protocol
Note 1 to entry: This type of telegram is denoted CHOICE in ISO/IEC 8825-2.
Note 2 to entry: There are several types of telegrams, but with the exception of the switch telegram, they are not
defined in this standard.
3.1.36
time slot
unit of 1 ms of RX or TX maturity time
3.1.37
transmitting device lead time
time between activation of transmitting device and the transmission of first preamble bit
3.1.38
transmitting device maturity time
maximum time for the transmission of one complete telegram as determined at the sending
device
3.1.39
transmitting device overtravel time
time between deactivation of TX blocks and end of last EOF bit

– 12 – 14543-3-10 © ISO/IEC:2012(E)

3.2 Abbreviations
ASK Amplitude Shift Keying
CRC Cyclic Redundancy Check
DC Direct Current
DESTID Destination device Identity

EIRP Effective Isotropic Radiated Power

ERP Effective Radiated Power
EOF End of Frame
INV Inverse bits
LBT Listen Before Talk
MSB Most Significant Bit
PRE Preamble
RX Receiver
RORG Telegram type
SOF Start Of Frame
SYNC Synchronisation bits
TX Transmitter
TXID Transmitting device Identity
WSP Wireless Short-Packet
4 Conformance
The three components of the WSP protocol system that are specified in this standard are the
transmitter, the receiver and the repeaters. The repeaters shall be able both to transmit and
to receive telegrams and thus shall support both the requirements for the transmitters and the
receivers.
To conform to this International Standard the components shall support one of the two
wireless frequencies specified unless another frequency is mandated by local regulations. For
the frequency chosen, the transmitter shall support all the transmitter requirements that are
not explicitly listed as optional, and the receiver shall support all the receiver requirements
that are not explicitly listed as optional. These requirements are specified in 5.2 and Clauses
6, 7 and 8.
5 Architecture
5.1 Generic protocol description
5.1.1 Overview
This subclause provides a comprehensive overview of the wireless short-packet (WSP)
protocol stack (see Table 1). The WSP is a lightweight layered protocol designed to minimise
both energy demand and the probability of a transmission collision. The WSP protocol stack
accommodates the structure of the OSI reference model (see ISO/IEC 7498-1).

14543-3-10 © ISO/IEC:2012(E) – 13 –

Table 1 – WSP protocol stack structure (OSI)

Wireless short-packet protocol (WSP) stack

Standard Layer Services Data units

Application
Not defined Presentation
in this
standard Session
Transport
Destination addressed telegrams
(Encapsulation/Decapsulation)
Network Switch telegram conversion TELEGRAM
(RORG and STATUS processing)
Repeating (STATUS processing)
Subtelegram structure
ISO/IEC
14543-3-10
Hash algorithms
Data Link Layer SUBTELEGRAM
Subtelegram timing
Listen before talk
Encoding/Decoding (INV and SYNC)
Physical BITS / FRAME
Wireless receiving/transmitting

5.1.2 Physical layer
At the physical layer the data are transmitted on either the 315 MHz or the 868,3 MHz
frequency band with 125 kbit/s data rate using amplitude shift keying (ASK). The functional
distance of the system is up to 300 m line-of-sight including the Fresnel zone and up to 30 m
in buildings. This may be subject to national regulations. One bit duration is 8 µs. The data
are transmitted in frames. A frame consists of the preamble (PRE), the start-of-frame
sequence (SOF), the subframes (with inverse (INV) and synchronisation (SYNC) bits) as well
as the end-of-frame sequence (EOF). For further details see Clause 6.
5.1.3 Data link layer
A subtelegram is the part of a frame from which the preamble (PRE), start-of-frame (SOF),
inverse bits (INV), synchronisation bits (SYNC) and end-of-frame (EOF) have been removed.
The subtelegram is transferred to the data link layer where the data integrity of the

subtelegram is checked. If the data integrity check fails, the subtelegram is discarded. An
additional task of the data link layer is to manage the subtelegram timing of the
received/transmitted subtelegram. The subtelegram timing is based on an algorithm that
ensures that the probability of subtelegram collisions in transit is as low as possible. To
reduce the collision risk the WSP protocol uses, if possible, a listen before talk (LBT)
technique. This algorithm (see 7.4) ensures that no transmission is initiated while the wireless
channel is occupied.
5.1.4 Network layer
Three tasks are performed at the network layer, namely a conversion process, a repeating
process and potentially a targeting process. The former performs a conversion between
switch and normal telegrams (see 8.2). The repeating process is used when the wireless
signals are too weak to reach the receiver directly and involves intermediate devices, i.e.,
repeaters that have been installed between the sender and the final recipient of the wireless
signal (see 8.3). Another process at this layer involves a telegram that contains target
addresses. Most telegrams are broadcast, and thus contain no destination identity (DESTID).
However, if a telegram is addressed, it is in an encapsulated format (see 8.4).

– 14 – 14543-3-10 © ISO/IEC:2012(E)

5.1.5 Transport layer
This layer is not described in this standard.

5.1.6 Session layer
This layer is not described in this standard.

5.1.7 Presentation layer
This layer is not described in this standard.

5.1.8 Application layer
This layer is not described in this standard.
5.2 Data unit description
The communication protocol is packet based and the data units can be of three different
types:
• Frame
• Subtelegram
• Telegram
A frame is the representation of the encoded data on the physical layer. It includes control
and synchronisation information for the receiver. A frame is transmitted as a bit by bit serial
sequence. A subtelegram is the result of a decoding process, in which this control (PRE, SOF,
INV and EOF) and synchronisation (SYNC) data are removed from the frame. The reverse
mechanism to extract a frame from a subtelegram is the encoding process.
Subtelegrams are processed at the data link layer. The WSP protocol is designed to work
mostly as a unidirectional protocol without handshaking. To ensure transmission reliability up
to three identical subtelegrams are transmitted within a specified time range. Each transmitted
subtelegram is an atomic unit and contains all the data that the composed telegram contains.
The data structure of a subtelegram is shown in Figure 1, where each byte is represented by
8 bits.
byte
1 1 … X 4 1 1
RORG DATA TXID STATUS HASH
Figure 1 – Structure of a subtelegram
The universal fields are:
• RORG – identifies the subtelegram type. With the exception of switch subtelegrams
(8.2) and encapsulated subtelegrams (8.4), these types are not defined in
this standard;
• DATA – the payload of the transmitted subtelegram;
• TXID – identifies the transmitter, each transmitter has a unique 4 byte identity;
• STATUS – identifies if the subtelegram is transmitted from a repeater and the type of
integrity control mechanism used. This field is not present in a switch
telegram;
• HASH – data integrity check value of all the bytes, see 7.3.

14543-3-10 © ISO/IEC:2012(E) – 15 –

The length of the subtelegram is not transmitted in the subtelegram structure. The length is

determined by counting the number of bytes starting with RORG and ending with HASH.

6 Layer 1 – Physical layer
6.1 Overview
The physical parameters that shall be supported by the WSP protocol are described in this

clause. The next subclause defines and illustrates the physical parameters for which

specifications for the WSP protocols are provided. Subclauses 6.3 and 6.4 specify the values

that shall be supported by the two wireless frequencies specified in this standard. They also

provide the link budget for these protocols.
The structure and encoding of the wireless protocol frames are found in 6.5.
6.2 General description
This subclause describes the physical parameters for the two wireless frequencies 315 MHz
and at 868,3 MHz of the WSP protocol, which shall be supported by the WSP signalling
system. This includes all electrical parameters and associated tolerances for the transmitter
and the receiver.
The TX centre frequency is the frequency the transmitter should emit. The centre of the
actual TX frequency may deviate from this value only by the maximum TX frequency
tolerance.
NOTE TX centre frequencies have been chosen below 1 GHz so as to achieve good penetration in buildings
together with low power consumption.
The maximum TX duty cycle defines the maximum time a transmitter may transmit related to
the total time. The reason for this parameter is that there are duty cycle regulations applicable
for the selected frequencies. For example, the WSP protocol at 315 MHz can choose to either
send 10 ms in a single transmission or transmit 10 times 1 ms during a 100 ms time frame,
both within the maximum of 10 ms per 100 ms time range.
TX modulation type, logical ‘0’ and logical ‘1’. The WSP protocol uses amplitude shift
keying (ASK) as modulations’ type. This means that the power level of the TX signal is
modified to transmit the information. The information is inverted on the physical layer. So
when a logical ‘1’ is transmitted, the TX power level is low. The power level is high when
transmitting a logical ‘0’. ASK has been selected in order to reduce power consumption when
transmitting a logical ‘1’.
– 16 – 14543-3-10 © ISO/IEC:2012(E)

Positive overshoot
Static high level
High state level
Positive undershoot
Bit duration
Mesial power level
Negative undershoot Static low level
Low state level
Negative overshoot
Low state amplitude
Figure 2 – Illustration of an ASK envelope and various physical parameters
Figure 2 shows an ASK envelope with one transition from a logical ‘1’ to ‘0’ and back to ‘1’.
The ASK envelope is the power level of the wireless signal over a given time. Figure 2 also
illustrates various physical parameters. These are needed for the understanding of how the
WSP protocol is defined.
The TX high state to low state amplitude ratio defines how much the TX signal is reduced
when transmitting a logical ‘1’. This ratio shall not be too low as most receivers need a
minimum TX high state to low state amplitude ratio. But it shall also not be too high as this
imposes problems for some automatic gain control mechanisms. The high-state level is
defined by the static high level. The static high level can be determined by switching the
transmitter to high state level and wait for all oscillations to cease. The low-state level is
defined by the static low level. The static low level can be determined by switching the
transmitter to low state level and wait for all oscillations to cease.

The maximum TX positive overshoot to high state amplitude ratio defines how much
higher the power level of the wireless signal is permitted to be with respect to the static high
level (see Figure 2).
The maximum TX negative overshoot to low state amplitude ratio defines how much lower
the power level of the wireless signal is permitted to be with respect to the static low level
(see Figure 2).
The maximum TX positive undershoot to high state amplitude ratio defines how much
lower the power level of the wireless signal is permitted to be with respect to the static high
level (see Figure 2).
The maximum TX negative undershoot to low state amplitude ratio defines how much
higher the power level of the wireless signal is permitted to be with respect to the static low
level (see Figure 2).
High state
amplitude
14543-3-10 © ISO/IEC:2012(E) – 17 –

The TX bit rate is the rate at which bits are transmitted.

NOTE A relatively high data rate has been chosen in order to get short bursts. This helps to reduce energy

consumption in the transmitter.

The TX bit duration is defined as the time between two transitions of the mesial power level
from a logical ‘1’ to a logical ‘0’ and back to a logical ‘1’ (see Figure 2).

The maximum TX bit rate tolerance is the maximum tolerable deviation from the TX bit rate
under which the transmitter is permitted to operate.

The maximum TX bit duration error is the maximum tolerable deviation from the TX bit
duration that the transmitter is permitted to use.
The TX lead time is defined as the time a signal starts to be emitted from the transmitter until
the first bit of the preamble starts.
The TX overtravel time is defined as the time a signal is still being emitted from the
transmitter after the last bit of the end of frame (EOF) has been transmitted.
The TX EIRP (Effective Isotropic Radiated Power) is the radiated power of an antenna
related to an ideal isotropic antenna. An ideal isotropic antenna has a gain of 0 dBi. The TX
EIRP can be calculated from the TX power and the antenna gain. For details see 6.3 and 6.4
below.
The RX blocking performance defines how resistant the receiver is to other signals. It
depends on the power level ratio between the other signal and that of the WSP protocol and
its deviation from the TX centre frequency.
The RX centre frequency is the frequency the receiver is intended to receive at.
Maximum RX frequency tolerance. The RX frequency may only deviate from the centre
frequency by the maximum RX frequency tolerance. It should be noted that the receiver
bandwidth shall be large enough to take account of the TX frequency deviation.
The RX high power state deviation between two consecutive high states tolerance is
mentioned because energy harvesting transmitters do not have a permanent power supply.
Fade in supply power may lead to changes in the output power level of the transmitter. The
receiver thus has to be able to tolerate such changes.
The tolerance of
Minimum TX positive overshoot to high state amplitude ratio,
Minimum TX negative overshoot to low state amplitude ratio,
Minimum TX positive undershoot overshoot to high state amplitude ratio,
Minimum TX negative undershoot to low state amplitude ratio,
Minimal RX bit rate,
Minimal RX bit duration error and
RX high state amplitude to low state amplitude ratio.
The receiver (RX) shall tolerate at least these minimum ratio values. Values outside this
range mean better performance. Figure 2 gives an illustration of these ratios.
The RX sensitivity is defined as the high state amplitude at the receiver input at which the bit
-3
error rate exceeds 10 due to noise. Lower values mean better performance, meaning the
transmitter and receiver can be further separated from each other.

– 18 – 14543-3-10 © ISO/IEC:2012(E)

The maximum RX power level is defined as the high state amplitude at the receiver input at

-3
which the bit error rate exceeds 10 due to signal distortion coming from too strong signals.

Higher values mean better performance, meaning that the transmitter and receiver can be

closer to each other.
6.3 Requirements for the 315 MHz WSP protocol

This subclause provides the requirements for the 315 MHz WSP protocol. Table 2 lists all

required parameter values that shall be supported for both a transmitter and a repeater.
Table 3 lists all required parameter values that shall be supported for both a receiver and a

repeater. These parameters have all been described in 6.2 above. In addition, values for the

link budget and the range of the system are also shown.

Table 2 – Transmitter requirements for the 315 MHz WSP protocol
Parameters Value or applicable standard
TX centre frequency f = 315 MHz
c
Maximum TX frequency tolerance
± 82,634 kHz
a
Maximum TX duty cycle 10 ms per 100 ms (10%)
TX modulation type ASK
b
logical ‘0’ High power state
b
logical ‘1’ Low power state
TX high state to low state amplitude ratio 20 dB to 36 dB
Maximum TX positive overshoot to high state amplitude 1 dB
ratio
Maximum TX negative overshoot to low state amplitude 4 dB
ratio
Maximum TX positive undershoot to high state amplitude 0,5 dB
ratio
Maximum TX negative undershoot to low state amplitude 2 dB
ratio
TX bit rate 125 kbit/s
TX bit duration 8 µs
Maximum TX bit rate tolerance
± 5 %
Maximum TX bit duration error
± 0,5 µs
c
TX lead time 0 µs to 56 µs
d
TX overtravel time
0 µs to 40µs
e
TX EIRP –9 dBm to –3 dBm
a
Due to national regulations.
b
Note that bits are inverted on the wireless interface
...