SIST ETS 300 471:1998
(Main)Radio Equipment and Systems (RES); Land mobile service; Access protocol, occupation rules and corresponding technical characteristics of radio equipment for the transmission of data on shared channels
- Abstract
This new ETS will contain the access protocol for shared channels as well as the requirements and methods of measurement relating to the parameters used in this protocol (as given in the I-ETS 300 113). (Proposals for amendments received by RES 2 will be considered, however fundamental changes to methods of measurement and corresponding limits are excluded.) This item and RE/RES-02-12, the revision of I-ETS 300 113 for upgrading to an ETS, need to be available at the same time.
- Status
- Published
- Publication Date
- 30-Sep-1998
- Technical Committee
- RES - Radio equipment and systems
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Oct-1998
- Due Date
- 01-Oct-1998
- Completion Date
- 01-Oct-1998
SIST ETS 300 471:1998 is the SIST adoption of ETS 300 471 Edition 1 from ETSI. It specifies the access protocol, occupation rules and related technical characteristics for radio equipment in the land mobile service that transmits data on shared channels, including mixed speech/data operation. The document is meant for manufacturers, test laboratories, administrators and users of professional mobile radio equipment who need a common way to control channel access and assess receiver timing.
What does SIST ETS 300 471:1998 specify?
SIST ETS 300 471:1998 sets out how radio equipment may access and occupy shared RF channels for data transmission, and it also gives two receiver timing measurement methods. It applies to professional mobile radio equipment and the associated frequency planning, and it allows any bit rate, constant envelope modulation or protocol that still meets the stated access parameters.
The scope includes shared-channel operation for data/data and speech/data. It also covers automatic channel access for mixed speech/data channels, where speech has priority over data. The document is not aimed at systems with a common central control facility or trunked systems on dedicated non-shared channels.
The document is organized into clauses on scope, references, definitions, general rules, technical characteristics, the access protocol, sharing examples, receiver delay measurements and measurement uncertainty. It also has one normative annex and two informative annexes.
| Annex | What it covers |
|---|---|
| Annex A | General arrangements for measurements involving radiated fields, including the test fixture and acoustic coupler |
| Annex B | Comments on the random part of the observation time |
| Annex C | Comments on traffic loading of shared channels |
What are the key requirements of SIST ETS 300 471:1998?
SIST ETS 300 471:1998 requires channel access to be based on carrier sensing and an observation time before transmission. In practice, equipment must listen first, wait through a fixed plus random observation period, and only then start transmitting if the channel appears idle.
Access rules for shared channels
Clause 6 says the access protocol is used for each occupation of the RF channel in data/data sharing and in speech/data sharing with automatic channel access. The channel is checked for idleness by carrier sensing, and if it is busy during the observation time, the process is repeated. This matters because it reduces collisions and makes sharing between independent users predictable.
For mixed speech/data channels, clause 4 gives speech priority over data. That means a data transmission must be limited so that it does not disturb speech users for long, which is important where both traffic types share the same channel.
Observation time and retransmission behavior
Clause 6.5 defines the observation time as a fixed part plus a random part. The random part uses a random number within an event field that increases after retransmissions. In practice, this is a backoff method: the first attempt uses a small choice set, and later attempts use a larger one to reduce repeated collisions.
Annex B explains the idea behind that backoff. After a failed attempt, the number of possible time slots is doubled, and after a successful transmission it is reset. This helps shared channels recover under load without requiring a central controller.
Starting and ending a transmission
Clause 6.6 requires the transmitter to start quickly after the observation period ends. Clause 6.3 also limits the reversion time between one transmitter stopping and the next one starting. For users, that means the equipment must switch over fast enough that other users cannot seize the channel in between.
Clause 6.7 distinguishes long data transmissions from short bursts on speech/data channels. For longer exchanges, the protocol uses a time interval and an additional reply window so acknowledgements can follow the initiating transmitter. For short bursts, the protocol allows brief data transmission on mixed channels, but with a stricter observation rule before each burst.
Carrier sensing and timing tests
Clause 6.4 says carrier sensing must detect RF signals with different modulation types, and the threshold depends on the frequency band for equipment covered by ETS 300 113 or I-ETS 300 113. This matters for compatibility because the receiver must recognize channel occupancy regardless of the modulation used by others.
Clause 8 gives the two receiver timing tests: carrier sense delay and receiver opening delay. These tests are used to verify how quickly the receiver recognizes a carrier and how quickly it can receive information after the test signal starts. Clause 9 then sets the allowed measurement uncertainty and requires it to be reported in the test record.
Conformity and test practice
Clause 4 requires a signed declaration that the equipment meets the access protocol requirements. Where control software is engineered by another party, that party must also sign. Clause 4 also says the receiver timing measurements are to be performed in an accredited laboratory. In practice, this creates a clear compliance trail for manufacturers, integrators and certification bodies.
What terms does SIST ETS 300 471:1998 define?
SIST ETS 300 471:1998 defines the main units and traffic structures used by the protocol so that measurements and channel use are interpreted consistently.
- bit - A binary digit used as the basic information unit.
- block - The smallest quantity sent over the radio channel, combining useful bits with redundancy bits.
- packet - One block or a continuous stream of blocks sent to one receiver or group of receivers.
- burst (physical) - A small number of consecutive packets sent within a short time under this access protocol.
- window - A time-limited set of related transmissions caused by one initiating transmitter.
- session - A complete exchange of packets, including initiation, data transfer and termination.
- initiating transmitter - The station that finishes the observation time and starts the transmission.
- reply - A transmission sent back to the initiating transmitter, such as an ACK, a NACK or useful data.
Who uses SIST ETS 300 471:1998?
SIST ETS 300 471:1998 is used by designers and suppliers of professional mobile radio equipment that share channels for data, and by organizations that mix speech and data on the same radio channel. It is also relevant to base-station and mobile equipment makers, because the protocol covers both base-to-mobile and mobile-to-base traffic.
Test laboratories use it to measure receiver carrier sense delay and receiver opening delay and to document measurement uncertainty. Quality managers and buyers use it to check whether equipment and software declarations, test methods and channel-access behavior match a shared-channel environment. Administrations may use it when defining channel-access conditions or licensing limits for shared channels.
Which standards are used with SIST ETS 300 471:1998?
SIST ETS 300 471:1998 relies on three ETSI publications named in its normative references.
- prETS 300 113 - Provides technical characteristics and test conditions for radio equipment with an antenna connector. Clause 5 and clause 8 use it for timing requirements and measurement methods.
- prETS 300 390 - Provides technical characteristics and test conditions for radio equipment with an integral antenna. Clause 5 and clause 8 use it for the corresponding timing requirements and measurement methods.
- I-ETS 300 113 - Provides the earlier combined analogue speech/non-speech equipment basis that the access protocol is built on, and its annex F is the published protocol referenced in the foreword.
What does the SIST ETS 300 471:1998 document contain?
SIST ETS 300 471:1998 contains the full access protocol description, the rules for speech/data and data/data sharing, and the receiver timing measurement methods. It includes figures that illustrate sharing situations, unsuccessful retransmission, and measurement arrangements for equipment with an antenna connector or an integral antenna.
Annex A gives the test fixture arrangement and the acoustic coupler arrangement used for radiated-field measurements. It also explains calibration so field-strength-based measurements can be related to signal-generator levels. Annex B explains the random access backoff logic, and Annex C comments on how speech traffic loading affects suitability on shared channels.
The document therefore serves both design and test work. It tells implementers how the channel-access behavior should work, and it gives laboratories the arrangements needed to verify the receiver timing parameters consistently.
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Frequently Asked Questions
SIST ETS 300 471:1998 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Radio Equipment and Systems (RES); Land mobile service; Access protocol, occupation rules and corresponding technical characteristics of radio equipment for the transmission of data on shared channels". This standard covers: This new ETS will contain the access protocol for shared channels as well as the requirements and methods of measurement relating to the parameters used in this protocol (as given in the I-ETS 300 113). (Proposals for amendments received by RES 2 will be considered, however fundamental changes to methods of measurement and corresponding limits are excluded.) This item and RE/RES-02-12, the revision of I-ETS 300 113 for upgrading to an ETS, need to be available at the same time.
This new ETS will contain the access protocol for shared channels as well as the requirements and methods of measurement relating to the parameters used in this protocol (as given in the I-ETS 300 113). (Proposals for amendments received by RES 2 will be considered, however fundamental changes to methods of measurement and corresponding limits are excluded.) This item and RE/RES-02-12, the revision of I-ETS 300 113 for upgrading to an ETS, need to be available at the same time.
SIST ETS 300 471:1998 is classified under the following ICS (International Classification for Standards) categories: 33.060.20 - Receiving and transmitting equipment. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST ETS 300 471:1998 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-1998
5DGLMVNDRSUHPDLQVLVWHPL 5(6 6WRULWHYNRSHQVNLKPRELOQLKNRPXQLNDFLM
'RVWRSRYQLSURWRNROSUDYLOD]DVHGHQRVWLLQXVWUH]QHWHKQLþQH]QDþLOQRVWLUDGLMVNH
RSUHPH]DSUHQRVSRGDWNRYSRNDQDOLKVVRXSRUDER
Radio Equipment and Systems (RES); Land mobile service; Access protocol, occupation
rules and corresponding technical characteristics of radio equipment for the transmission
of data on shared channels
Ta slovenski standard je istoveten z: ETS 300 471 Edition 1
ICS:
33.060.20 Sprejemna in oddajna Receiving and transmitting
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN ETS 300 471
TELECOMMUNICATION December 1995
STANDARD
Source: ETSI TC-RES Reference: DE/RES-02-14
ICS: 33.060.20
access, data, mobile, protocol, radio, testing
Key words:
Radio Equipment and Systems (RES);
Land mobile service;
Access protocol, occupation rules and corresponding technical
characteristics of radio equipment for the
transmission of data on shared channels
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1995. All rights reserved.
New presentation - see History box
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ETS 300 471: December 1995
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.
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ETS 300 471: December 1995
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions.8
4 General.8
4.1 Sharing speech/data.8
4.2 Sharing data/data.8
4.3 Conformity to this ETS.8
4.4 Interpretation of the measurement results.9
5 Technical characteristics of the equipment.9
6 Access protocol.9
6.1 General .9
6.2 Principles .9
6.3 Procedure .9
6.4 Carrier sensing.10
6.5 Observation time.10
6.6 Initiation of the transmitter .11
6.7 Duration of the RF channel occupation (time interval).11
6.7.1 Transmissions of data packets exceeding 300 ms .11
6.7.2 Transmissions of data packets not exceeding 300 ms (speech/data
channels).11
7 Examples of sharing situations .12
8 Methods of measurement for receiver delays.17
8.1 Carrier sense delay.17
8.1.1 Definition .17
8.1.2 Method of measurement .17
8.1.3 Limit.18
8.2 Receiver opening delay.18
8.2.1 Definition .18
8.2.2 Method of measurement .18
8.2.3 Limit.19
9 Measurement uncertainty.19
Annex A (normative): General arrangements for measurements involving the use of radiated
fields .20
A.1 Test fixture .20
A.1.1 Description.20
A.1.2 Calibration.20
A.1.3 Mode of use .21
A.2 Acoustic coupler.21
A.2.1 General .21
A.2.2 Description.21
A.2.3 Calibration.22
A.3 Bibliography.22
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ETS 300 471: December 1995
Annex B (informative): Comments concerning the random part of the observation time. 23
Annex C (informative): Comments concerning the traffic loading of shared channels. 24
History. 25
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ETS 300 471: December 1995
Foreword
The access protocol described in this ETS is based on the access protocol published as annex F of
I-ETS 300 113 [3].
Transposition dates
Date of adoption of this ETS: 17 November 1995
Date of latest announcement of this ETS (doa): 31 March 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 September 1996
Date of withdrawal of any conflicting National Standard (dow): 30 September 1996
This ETS can be implemented for equipment meeting the requirements of ETSI standards
e.g. ETS 300 113 [1] and ETS 300 390 [2].
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ETS 300 471: December 1995
Blank page
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ETS 300 471: December 1995
1 Scope
This ETS applies to equipment designed to operate within the professional mobile radio service and to the
associated frequency planning.
This ETS applies to equipment for the transmission of data on shared channels; it also contains two
methods of measurement used for the assessment of receiver timing parameters.
This ETS specifies an access protocol and occupation rules for data communications on radio channels
shared by different users. It may be used for data communications over channels originally intended for
speech use. This ETS gives freedom for the use of any bit rate, any constant envelope modulation or any
type of protocol which fulfills the normative parameters of this ETS to access a shared radio channel.
The access protocol specified in this ETS also permits the sharing of speech and data communication.
This access protocol applies to single frequency simplex operation (and two frequency repeater
operations with the repeater in duplex mode and the mobile units in simplex mode). This access protocol
is applicable for:
- multiple data only users, independent of each other, which do not share a common central control
facility, but may share a common single or two frequency radio channel;
- multiple mixed analogue speech and data users, independent from each other, which do not share
a common central control facility, but may share a common single, or two frequency, radio
channel and where speech is to have priority over data transmissions.
This access protocol is not applicable for data users with common central control facilities or for trunked
systems operating on dedicated non shared channels.
In the case of analogue transmissions, the corresponding access protocol is known as the
"radio-discipline" of the users.
Within the limits set out in this ETS, each group of users may use its own communication protocol.
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] prETS 300 113 (1995): "Radio Equipment and Systems (RES); Land mobile
service; Technical characteristics and test conditions for radio equipment
intended for the transmission of data (and speech) and having an antenna
connector".
[2] prETS 300 390 (1995): "Radio Equipment and Systems (RES); Land mobile
service; Technical characteristics and test conditions for radio equipment
intended for the transmission of data and speech and using an integral
antenna".
[3] I-ETS 300 113 (1992): "Radio Equipment and Systems (RES); Land mobile
service Technical characteristics and test conditions for non-speech and
combined analogue speech/non-speech equipment with an internal or external
antenna connector, intended for the transmission of data".
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ETS 300 471: December 1995
3 Definitions
For the purpose of this ETS, the following definitions apply:
bit: Binary digit.
block: The smallest quantity of information sent over the radio channel. A constant number of useful bits
are always sent together with the corresponding redundancy bits.
packet: One block or a contiguous stream of blocks sent by one (logical) transmitter to one particular
receiver or one particular group of receivers.
burst (physical): Transmission of a small number of consecutive packets within a period not exceeding
300 ms in accordance with this access protocol.
transmission (physical): One or several packets transmitted between power on and power off of a
particular transmitter.
window: A set of inter-related transmissions resulting from the action of the "initiating transmitter", and
limited in time by the access protocol and corresponding occupation rules to a duration of t + Δt .
t t
session: A set of inter-related exchanges of packets occupying one or several windows or parts thereof (if
applicable). It corresponds to a complete interactive procedure for interchanging data between users,
comprising initiation, data transmission and termination procedures. The session can be short
(e.g. 2 packets) or long (e.g. one full page of text).
message: User data to be transferred in one or more packets in a session.
initiating transmitter: The initiating transmitter is the station that has completed the "observation time"
(see subclause 6.5) and therefore starts a transmission. This initiates a window and triggers the timer t .
t
reply: A transmission by a station as an answer to the "initiating transmitter". This reply can be an
acknowledge ("ACK") or a negative acknowledge ("NACK") or a longer packet of useful information.
4 General
4.1 Sharing speech/data
This access protocol gives speech priority over data on mixed speech/data channels. In order to limit
annoyance to speech users, the duration of data transmissions shall be limited in accordance with
subclause 6.7.
4.2 Sharing data/data
On frequencies assigned only to data communication users (without common central control facilities) the
access protocol provides access to independent users with equal priority.
4.3 Conformity to this ETS
A signed declaration shall be provided as a confirmation that the equipment meets the requirements of
this access protocol. This may be submitted by the manufacturer with the application form for tests.
In the case where the controlling software for the equipment has not been engineered by the
manufacturer of the radio equipment, the party responsible for engineering the controlling software shall
provide a signed declaration that the equipment meets the requirements of this access protocol.
Measurements of receiver carrier sense delay and opening delay shall be performed in an accredited test
laboratory, possibly together with the tests corresponding to ETS 300 113 [1].
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ETS 300 471: December 1995
4.4 Interpretation of the measurement results
The interpretation of the results recorded in a test report for the measurements described in this ETS shall
be as follows:
a) the measured value related to the corresponding limit shall be used to decide whether an
equipment meets the minimum requirements of this ETS;
b) the actual measurement uncertainty of the test laboratory carrying out the measurement, for each
particular measurement, shall be included in the test report;
c) the values of the actual measurement uncertainty shall be, for each measurement, equal to or lower
than the figures given in clause 9 (absolute measurement uncertainties).
5 Technical characteristics of the equipment
The timing requirements that the equipment shall fulfil in order to operate correctly and efficiently can be
found in ETS 300 113 [1], subclauses 5.1.7 and 5.1.8, ETS 300 390 [2], subclauses 5.1.5 and 5.1.6 and
subclauses 8.1.3 and 8.2.3 of this ETS.
The corresponding methods of measurement can be found in ETS 300 113 [1], subclauses 8.8 and 8.9,
ETS 300 390 [2], subclauses 8.5 and 8.6 and in subclauses 8.1 and 8.2, of this ETS.
6 Access protocol
6.1 General
The access protocol shall be used for each occupation of the Radio Frequency (RF) channel for sharing
data/data and for sharing speech/data with automatic channel access.
6.2 Principles
The equipment determines whether or not the channel is, and has been, idle for a certain period (the
observation time) by means of carrier sensing.
The observation time consists of a fixed part and a randomly selected part. When the channel still
appears to be idle at the end of the observation time, the transmitter is initiated and powered up within a
specified time.
The duration of the emission is limited (see subclause 6.7).
6.3 Procedure
The equipment shall determine whether or not the channel is, and has been, idle for a certain period (the
observation time t ), by means of carrier sensing (see subclause 6.4). The observation time t consists of
o o
a fixed part t and a randomly selected part t .
f r
If the channel is occupied during part of the observation time, the process shall be repeated (without
changing m (see subclause 6.5).
If the channel appears to be idle throughout the observation time, the transmitter shall be initiated and
powered up within the specified time (attack time; see ETS 300 113 [1], subclause 8.8 or ETS 300 390 [2],
subclause 8.5). The channel can then be seized for the duration of one time interval. The maximum length
t of this interval depends on the frequency sharing category (data/speech, data/data).
t
If a re transmission is required (due, for example, to a "collision", i.e. a simultaneous channel access by
several users), the observation process shall be repeated and the channel shall be detected as idle prior
to a repetition of a transmission.
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ETS 300 471: December 1995
Within one time interval, the following radio traffic may take place:
a) from a base station to one or several mobiles;
b) from a mobile to a base station;
c) between mobiles.
To ensure that no other user can access the channel during a time interval, the reversion time t , the time
c
between transmission of a message and reception of the corresponding acknowledgement and/or reply,
shall not exceed 50 ms. The reversion time t is the time between the switch off of one transmitter and the
c
switch on of the other. The points of switch off and switch on are considered to be the points at which the
transmitter power is 50 % of the rated carrier power.
6.4 Carrier sensing
Carrier sensing is the detection of whether the RF level in the receive channel exceeds a given threshold.
The carrier sense shall be able to detect RF signals with different types of modulation (e.g. F3E, G3E,
F1D, F2D, G1D).
The channel shall be regarded as in use during the observation time (see subclause 6.5) if the level of the
RF signal on the channel exceeds a certain level. For equipment meeting ETS 300 113 [1] or I-ETS 300
113 [3], this threshold level shall be as defined in table 1.
Table 1: Threshold levels
Band Threshold level in
dBμμV emf
30 - 137 MHz 12
> 137 - 300 MHz 6
> 300 MHz 0
The carrier sense delay is specified in subclause 8.1.3.
6.5 Observation time
The observation time shall start within 10 ms after each time that the RF channel has become idle. It shall
also start at power on.
The observation time t is the sum of the fixed part t and the random part t = n × t
o f r i
t = t + n × t .
o f i
The fixed part, t , of the observation time shall be:
f
- on pure data channels: 60 ms ± 1 ms;
- on combined speech/data channels: 2 000 ms ± 1 ms;
except as specified in subclause 6.7.2.
The increment time t shall be 50 ms ± 0,1 ms.
i
The number n is a random integer number from 1 to m (1 ≤ n ≤ m); this means that 1 to m is the event
field of the random number n. The random number n shall be determined by use of a random generator
with a uniform distribution (see also annex B).
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ETS 300 471: December 1995
To achieve short delays during low traffic, the observation time should be short, i.e. m should be small.
Therefore in this access protocol, m shall be set to 4 for the first trial.
A short random part of the observation time however, increases the probability of several users
simultaneously accessing the channel for a time interval.
Therefore, when a re transmission is required (e.g. in the case of no acknowledge, see figure 2), the
observation process shall be repeated and the channel shall be detected as idle during a new t befor
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