ETSI TR 102 021-4 V1.4.1 (2011-08)

Technical Report
Terrestrial Trunked Radio (TETRA);
User Requirement Specification TETRA Release 2.1;
Part 4: Air Interface Enhancements

2 ETSI TR 102 021-4 V1.4.1 (2011-08)

Reference
RTR/TETRA-01193
Keywords
TETRA, user
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3 ETSI TR 102 021-4 V1.4.1 (2011-08)
Contents
Intellectual Property Rights . 4
Foreword . 4
Introduction . 4
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 7
4 User Requirement Specification . 8
4.1 Introduction . 8
4.2 Network performance aspects . 8
4.2.1 Overview of network performance aspects . 8
4.2.2 Enhanced network capacity . 8
4.2.3 Location positioning accuracy better than base station site location . 9
4.2.4 Improved cell hand-over decision and management . 9
4.2.4.1 General improvements . 9
4.2.4.2 Expedited handover . 10
4.2.5 Improving end to end time delay performance . 10
4.2.6 Improved spectrum efficiency . 10
4.2.7 Base station cell size beyond the 58 km radius limitation of TETRA Release 1 . 10
4.2.8 Improved RF performance . 11
4.2.9 SDS improvements . 11
4.2.10 SDS concatenation . 11
4.2.11 User aliases . 12
4.3 Terminal performance aspects . 12
4.3.1 Overview of terminal performance aspects . 12
4.3.2 Improved battery operating life for daily PMR shift use . 13
4.3.3 Improved battery operating life for telephony use . 13
4.3.4 Improved battery operating life for data use . 13
4.3.5 Weight reduction . 14
4.3.6 Size reduction . 14
4.3.7 Co-existence of terminals (MSs) and/or base stations (BSs) . 14
4.3.8 Harmonised cell (re)selection criteria . 14
4.3.8.1 Priorities . 14
4.3.8.2 Use of the Cell Service Level . 15
4.3.8.3 Subscriber class . 17
4.3.8.4 Pre-programmed cell/frequency information . 18
4.3.8.5 Effect of higher/lower cell preference levels to cell reselection. 18
4.4 Location information aspects . 18
4.4.1 Location positioning applications . 18
4.4.2 Location positioning accuracy and resolution. 19
4.4.3 Location positioning updates . 19
4.4.4 Location positioning availability . 19
4.4.5 Location positioning reliability . 19
4.4.6 Location positioning terminal impact . 19
4.4.7 Location positioning air interface enhancement . 20
4.4.8 Location information transfer to support APL/AVL applications . 20
4.4.9 Location positioning security issues . 22
Annex A: Operational-Tactical Address . 23
History . 24
ETSI
4 ETSI TR 102 021-4 V1.4.1 (2011-08)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Terrestrial Trunked Radio (TETRA).
The present document is part 4 of a multi-part deliverable covering the User Requirement Specifications (URSs) for
TETRA Release 2 and Release 2.1, as identified below:
Part 1: "General overview" (Release 2.1);
Part 2: "High Speed Data" (Release 2.1);
Part 3: "Codec" (Release 2);
Part 4: "Air Interface Enhancements" (Release 2.1);
Part 5: "Interworking and Roaming" (Release 2.1);
Part 6: "Smart Card and Subscriber Identity Module" (Release 2.1);
Part 7: "Security" (Release 2.1);
Part 8: "Air - Ground - Air services" (Release 2);
Part 9: "Peripheral Equipment Interface" (Release 2.1);
Part 10: "Local Mode Broadband" (Release 2.1);
Part 11: "Over The Air Management" (Release 2.1);
Part 12: "Direct Mode Operation" (Release 2.1).
Introduction
The Terms of Reference for TC TETRA approved at ETSI Board meeting #69, November 2008 is to produce ETSI
deliverables (and maintenance thereafter) in accordance with the following requirements:
The Terms of Reference for TC TETRA are to produce ETSI deliverables (and maintenance thereafter) in accordance
with the following requirements:
a) The provision of user driven services, facilities and functionality as required by traditional Professional Mobile
Radio (PMR) user organizations such as the Emergency Services, Government, Military, Transportation,
Utility and Industrial organizations as well as Public Access Mobile Radio (PAMR) Operators.
b) The evolution and enhancement of TETRA as required by the market with the provision of new services,
facilities and functionality made possible by new technology innovations and standards.
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5 ETSI TR 102 021-4 V1.4.1 (2011-08)
c) Further enhancements of the TETRA standard in order to provide increased benefits and optimization in terms
of spectrum efficiency, network capacity, system performance, quality of service, security and other relevant
parameters.
d) The backward compatibility and integration of the new services, facilities and functionality with existing
TETRA standards in order to future-proof the existing and future investments of TETRA users.
Technical Objective
TETRA is one of a number of digital wireless communication technologies standardized by ETSI.
ETSI TC TETRA produces standards and/or adapts existing standards for efficient digital PMR and PAMR voice and
data services, including broadband evolution.
The present document provides the User Requirement Specifications for the TETRA air interface enhancements.
The URS is required by TC TETRA to guide the enhancement of the current TETRA standard, mainly the evolution of
the HSD standard part towards broadband.
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6 ETSI TR 102 021-4 V1.4.1 (2011-08)
1 Scope
The present document provides the User Requirement Specifications (URS) for the TETRA air interface enhancements
translated into terms of:
• network performance aspects;
• terminal performance aspects;
• location information aspects.
The present document is applicable to the specification of TETRA Release 2.1 equipment.
The user requirements contained in the present document are described in non-technical terms and are based on
discussions in TC TETRA WG1 and on an analysis of the results for air interface enhancements from the 2001 TETRA
Release 2 Market Questionnaire and the 2007 Future of TETRA workshop [i.1].
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TR 102 621: "Terrestrial Trunked Radio (TETRA); TWC2007 Future of TETRA workshop
report".
[i.2] ETSI TR 101 987: "Terrestrial Trunked Radio (TETRA); Proposed Air Interface Enhancements
for TETRA Release 2; Analysis and Feasibility Assessment".
[i.3] ETSI TR 102 021-8: "Terrestrial Trunked Radio (TETRA); User Requirement Specification
TETRA Release 2; Part 8: Air - Ground - Air services".
[i.4] ETSI TR 102 021-11: "Terrestrial Trunked Radio (TETRA); User Requirement Specification
TETRA Release 2.1; Part 11: Over-The-Air Management".
[i.5] ETSI EN 300 392-2: "Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D); Part 2: Air
Interface (AI)".
[i.6] ETSI TS 100 392-18-1: "Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D) and Direct
Mode Operation (DMO); Part 18: Air interface optimized applications; Sub-part 1: Location
Information Protocol (LIP)".
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7 ETSI TR 102 021-4 V1.4.1 (2011-08)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
TETRA Release 2: Work Programme with new terms of reference within ETSI Project TETRA to enhance the services
and facilities of TETRA in order to meet new user requirements, utilize new technology and increase the longevity of
TETRA within the traditional market domains of PMR and PAMR
TETRA Release 2.1: Work Programme within TC TETRA to enhance the services and facilities of TETRA in order to
meet new user requirements, utilize new technology and increase the longevity of TETRA within the traditional market
domains of PMR and PAMR
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AI Air Interface
APL Automatic Person Location
AVL Automatic Vehicle Location
C-SCCH Common Secondary Control Channel
CSL Cell Service Level
DTX Discontinuous Transmission
ETSI European Telecommunications Standards Institute
GPS Global Positioning System
GTSI Group TETRA Subscriber Identity
HSD High Speed Data
ITSI Individual TETRA Subscriber Identity
LIP Location Information Protocol
MCCH Main Control Channel
MS Mobile Station
OPTA Operational-Tactical Address
PAMR Public Access Mobile Radio
PMR Private Mobile Radio
PTT Press To Talk
RF Radio Frequency
RSSI Received Signal Strength Indicator
SC Subscriber Class
SDS Short Data Service
TA Timing Advance
TEDS TETRA Enhanced Data Services
TETRA TErrestrial Trunked RAdio
TR Technical Report
URS User Requirement Specification
V+D Voice plus Data
WGS 84 World Geodetic System 1984
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4 User Requirement Specification
4.1 Introduction
The enhancements of the TETRA air interface standard aim at providing increased benefits and optimization in terms of
spectrum efficiency, network capacity, system performance, quality of service, size and cost of terminals, battery life,
and other relevant parameters. Other possible air interface enhancements are providing increased coverage range and
low cost deployments for applications such as airborne public safety, maritime, rural telephony and "linear utilities"
(e.g. pipelines). Provisioning of location information is another service that could be provided by enhancements of the
TETRA air interface standard.
4.2 Network performance aspects
4.2.1 Overview of network performance aspects
The network performance aspects to be enhanced or supported in TETRA Release 2 are listed below:
• improved spectrum efficiency;
• enhanced network capacity;
• improved end-to-end time delay performance;
• Base Station site RF coverage beyond the current 58 km radius limitation of TETRA Release 1;
• improved RF performance;
• location positioning accuracy better than base station site location (Cell ID);
• improved cell hand-over decision and management;
• SDS improvements including concatenation;
• user aliases.
Most of these elements are difficult to quantify by users. The user requirements can generally be expressed as the more
improvement the better. Some of these elements require substantial standardization effort. These requirements will
compete for standardization resources and, as such, compromise each other. In the 2001 questionnaire responses, users
indicated how they judged the relative importance of these elements. This gives an indication which items deserve most
standardization effort. Some enhancements may be satisfied by implementation rather than standardization.
The different aspects are listed in clauses 4.2.2 to 4.2.7 in descending order of TETRA user market importance as
judged by the 2001 questionnaire panel, further clauses under clause 4.2 are in no specific order of importance.
4.2.2 Enhanced network capacity
Enhanced network capacity is the most important requirement for the general TETRA market and also in all market
segments.
Most of the respondents (users/operators) in 2001 were still starting up their TETRA networks. These networks were
not under normal or full load and most respondents could only estimate the capacity load of their systems. The majority
of those users had traditional analogue private open channel PMR systems. Therefore, it was very difficult (depending
on the individual user/organization behaviour) to estimate how effective the statistical multiplexing of TETRA trunking
will be. It is likely that the capacity gain of trunking has been underestimated.
As a result of underestimating the trunking effect, enhancing network capacity could be too high on the list of the
general user requirements.
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9 ETSI TR 102 021-4 V1.4.1 (2011-08)
4.2.3 Location positioning accuracy better than base station site location
Location positioning accuracy better than base station site location (Cell ID) is also a very important requirement for the
general TETRA market. It is required in both Public Safety and PAMR market segments.
The requirements for location positioning are handled in detail in clause 4.4.
4.2.4 Improved cell hand-over decision and management
4.2.4.1 General improvements
Improved cell hand-over decision and management is an important requirement for the general TETRA market. It is
required in both the Public Safety and PAMR market segments.
User/operators responsible for more mature TETRA networks tend to judge this item more important than
users/operators with limited TETRA experience. This could indicate that the importance of this item is underestimated
by the TETRA users/operators starting up their TETRA networks.
The relative importance of this item is probably higher than its ranking suggests.
Some problems experienced in the early networks were:
• cell dragging by an MS;
• handover to a wrong cell.
Important user requirements (for networks under normal or full load) include:
• load management;
• need for consistent behaviour from all MS suppliers;
• need for (future) flexibility in the handover methodology.
When the networks are under normal or full load, improved cell selection will also be part of the solution for enhancing
network capacity.
Most networks can be considered as built in two layers; a macro layer and a micro layer. Some networks have also other
layers, e.g. air-to-ground, that are not specifically covered below although the general principles should apply for them
also.
The macro layer provides the general network coverage. This layer delivers coverage mainly in low to average user
density zones; mostly rural areas. This macro layer generally uses very high (hilltop) sites, with antennas substantially
above clutter height.
The micro layer fulfils an additional requirement, depending on the type of network. In PAMR networks the microcells
deliver extra capacity in high user-density zones; mostly urban areas. In Public Safety networks this micro layer
delivers mainly extra coverage (including indoor for hand portables) in urban areas. The Public Safety microcells differ
from the macro cells mainly by their location (city centre instead of hilltop), not by their RF parameters, and as such
these cells are not really small.
In both types of networks there is need for a cell selection mechanism to prevent too much traffic going via the
macrocells. Macrocells should only be used when no other cell can be used because of bad signals or high speed.
In some micro layer solutions, especially in big cities with high cell density and a desire for indoor coverage, the signal
outdoors becomes "too good", creating a cell dragging problem. Here one cell may provide very good coverage ranging
beyond its neighbour cells" planned coverage area. An MS may be using this cell and move onto the other side of the
neighbours, without a need to hand over looking based on the RSSI. Then, when the user goes behind a big building the
signal may be completely cut off. If all neighbours get "cut off" at the same time too, the MS has to spend some time
scanning the frequency band to establish a serving cell, creating a break in the service. Although careful tuning of the
handover parameters and neighbour cell information can be used to minimise this effect, in these cases it would help if
the terminals could be "tuned" to hand over earlier. However, it is recognised that handing over too early is generally
not a good idea, so this feature should be geographically limited rather than a network wide setting.
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The current standard limits the possibilities perhaps too much in some cases, forcing handheld and mobile terminals to
work with the same threshold values. As mobile terminals tend to have more effective antennas and a higher
transmission power this may lead to problems in some cases. In most cases, the ideal "handover sensitivity" would be
similar from the user's point of view regardless of the type of terminal he is using.
Terminal aspects of improved cell reselection criteria are covered in clause 4.3.8.
4.2.4.2 Expedited handover
Radio network planning for road and railway tunnels is very challenging due to the fast fading nature of cells. Often, the
received RF signal from the current cell degrades rapidly at the same time as the new cell's RF signal level raises
rapidly, unlike "out in the open" where the terminal has more time to react to changed RF levels. Typical places where
this happens are entry/exit points of tunnels and stretches of tunnels where the radio network has been built to enforce a
handover by deliberately attenuating the signal within a short distance to an unusable level.
If the terminal is not prepared for this fairly sudden (but predictable) loss of signal, the user may experience a cut in
service when the terminal starts to think about changing cell when the signal from the current cell is effectively lost
already.
Careful tuning of network parameters can minimise the effects of the fast fading, but often creates other problems.
Introduction of new fast train lines across the world means that the problems are likely to become worse in the future
unless the handover process is improved to support a mechanism whereby the terminal is aware of the possibility,
allowed to hand over faster than normally, and prepared for it.
For this feature to work properly, the network has to have a way of informing the terminals of this possibility and the
handover rules have to allow a fast handover in cases where the received signal level disappears quickly, if it has been
indicated that the terminal should do this.
However, in order to avoid a huge increase in handovers, it should be able to selectively apply this feature to dedicated
cases (cell borders) where a typical radio user is expected to experience a predictable rapid reduction in the received
signal level, e.g. when going into a tunnel.
Expedited cell reselection is covered by EN 300 392-2 [i.5] with other cell reselection types.
4.2.5 Improving end to end time delay performance
Reducing end-to-end time delay for voice was earlier required in both the Public Safety and PAMR market segments
but not identified in the 2007 TWC workshop as an area that requires further improvement.
4.2.6 Improved spectrum efficiency
Spectrum efficiency is important for the PAMR market segment and required by some Public Safety users.
Since most of the respondents (users/operators) to the 2001 questionnaire were still starting up their TETRA networks,
it was possible that the TETRA network capacity could have been underestimated. If this was the case, spectrum
problems could have also been overestimated. Whatever the underlying reason, by 2010 experienced TETRA operators
had identified lack of spectrum to be a real problem for expansion and in some cases even for keeping up with the
slowly increasing capacity demand from their current user base.
Improving the frequency reuse factor could be a way to improve spectrum efficiency and this has been taken into
account in Release 2 HSD development. The size of cells and resources put into frequency planning also play a part in
how spectrum efficient TETRA networks can be.
4.2.7 Base station cell size beyond the 58 km radius limitation of TETRA
Release 1
Base station cell size beyond the 58 km radius limitation of TETRA Release 1 (due to time slot structure) is required by
Public Safety, the military and utilities.
Requirement scenarios include mostly aeronautical and maritime use where there are little or no obstacles between the
transmitting and receiving parties.
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The aeronautical use case and more detailed size requirements are covered in URS part 8, Air-Ground-Air services
TR 102 021-8 [i.3].
The air interface standard EN 300 392-2 [i.5] allows a larger maximum path delay responding to a maximum cell radius
of 83 km or a 100 % increase to the (theoretical) coverage area of a cell.
4.2.8 Improved RF performance
An improvement in the RF performance by means of better receiver sensitivity, better air interface error correction or
similar solution(s) is needed to improve usability in rural areas and indoors. The extended cell size does not help in
these cases where the problem is not the distance between the base station and the terminal. Other solutions should be
sought to solve these problems. Private TETRA networks do not have the same subscriber numbers as commercial
cellular networks, making the economic justification for simply adding base stations and other coverage solutions much
harder.
These two cases might require separate solutions as indoor coverage tends to be needed in built up areas where the
outdoor signal levels are normally reasonably high, whereas in the rural areas the outdoor signal level and quality is low
due to the attenuation caused by hills, forests etc and where one part of the problem might be reflections from big
nearby objects.
Requirement scenarios include private houses and other indoor locations where special coverage solutions are not
economically justifiable, "linear cells" (e.g. pipelines, railways) and large rural cells (large low-traffic areas).
4.2.9 SDS improvements
One of the highest scoring improvement areas in TETRA according to the participants of the 2007 workshop "Future of
TETRA" [i.1] was "increased speed, capacity, and efficiency of SDS".
Even though the SDS service has been serving the TETRA community adequately for several years, the workshop
attendees thought that there is a need to improve the efficiency of the SDS service (e.g. under highly loaded network
conditions) for applications which may require faster delivery, a higher data capacity (beyond the current maximum)
and more SDS message capability in the TETRA network.
Many early data applications utilise SDS as the data bearer and the wide availability of GPS-enabled terminals lead to
common use of LIP or other location information protocols, all typically using the SDS messaging service. A more
efficient mechanism, either available all the time or during network congestion, would keep the users happy and
continue the success of AVL and APL solutions.
The requirement applies to SDS messages carried over either V+D or TEDS. The experience based limitations at the
2007 workshop were naturally V+D related. An HSD-only network introduced by direct access TEDS in Release 2.1
should be able to provide similar or better SDS performance as the Release 2.1 V+D part does.
4.2.10 SDS concatenation
In addition to a faster and more efficient SDS service there is a need to have longer SDS messages. It should be able to
send these both to individual and group addresses.
These longer messages should support, but not be limited, to text messages.
There is a delicate balance between the convenience of using SDS and the size of a data file, e.g. a text message,
reaching the destination within a reasonable time, taking into account that radio is an unreliable bearer and therefore
each extra part increases the probability of at least one bit getting corrupted on the way. Additionally, it should be
remembered that SDS messages use the control channel and sending large files using SDS service is not recommended
for this reason.
One normal SDS message can carry 140 bytes of payload. It is expected a suitable balance between the restrictions
mentioned earlier and the advantages of using SDS instead of packet data is somewhere around maximum 500 bytes to
1 500 bytes of payload in one concatenated SDS message.
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12 ETSI TR 102 021-4 V1.4.1 (2011-08)
An MS user should always be informed about the reception status of a concatenated SDS message. It should be clear to
the recipient whether the whole message is presented or are there still some message parts to be received. An example
of a message that should be displayed also when partially received is a long text message. The (partial) message should
be available for display once the first part has been received and should be displayed up to the first part not received yet.
The recipient of an individually addressed concatenated message should be able to acknowledge the whole message
when it has been successfully received and ideally also each part separately as they arrive, to enable the sending party to
re-send either the whole message or the missing parts. In addition to acknowledging each part separately it would be
good to have some means of requesting missing parts after it is obvious one or more have been lost.
The concatenated SDS service should support end-to-end encryption, ideally supporting two ways of doing this; the
whole message encrypted as one package and each part encrypted separately. While there may be benefits in encrypting
the whole message as only one packet, encrypting each part separately would allow also partial messages to be used by
the receiving party.
The transport mechanism of concatenated SDS messages is covered by EN 300 392-2 [i.5].
4.2.11 User aliases
There is a requirement for users to be aware at all times of who is talking (by their alias). Some users might also need to
know who else is in the call and their group membership(s). To satisfy these kind sof requirements there is a need to
easily, quickly and efficiently dynamically update and change aliases network wide on a regular basis.
Some examples are:
• individual call aliases;
• group membership of a selected group of users or all members of a talk group, e.g. table with radio aliases in
the first column and current group membership(s) in the second column;
• more information about the ongoing communication (talking party, new group members, etc.).
A typical radio user would only be interested in knowing who is transmitting at the moment, whereas e.g. control rooms
or field commanders might be interested in the wider set of the functionality described in this clause.
Preferably there should be only one place (database) in the system where the one-to-one relation between ITSI
(or GTSI) and the "alias" (name) is made. If a subscriber receives a call within a group and/or from a user for whom it
does not know the aliases, these should be delivered over the air-interface. For the best user experience, a centrally
managed over-the-air phonebook solution, refer to TR 102 021-11[i.4], could be used to ensure that all likely needed
aliases already exist in the MS.
As nationwide TETRA networks may contain hundreds of thousands of users, it is assumed that not all user aliases will
be programmed and maintained in every MS. One way to provide the user "alias" (name) dynamically to all recipients
of the call is to use OPTA, see annex A.
4.3 Terminal performance aspects
4.3.1 Overview of terminal performance aspects
The terminal performance aspects to be enhanced in TETRA Release 2 and Release 2.1 are listed below:
• size reduction;
• weight reduction;
• improved battery operating life for daily PMR shift use;
• improved battery-operating life for Telephony use;
• improved battery operating life for data use;
• co-existence of terminals and network;
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13 ETSI TR 102 021-4 V1.4.1 (2011-08)
• harmonised cell re-selection criteria;
• operational-tactical address.
The majority of these elements are difficult to quantify by users. The user requirements can generally be expressed as
the more reduction or improvement the better. Some of these requirements are compromising others. The user
responders to the 2001 questionnaire indicated how they judged the relative importance of these elements. This gives an
indication what terminal aspects could be compromised when it is not possible to improve all aspects.
The different aspects are listed in clauses 4.3.2, 4.3.3, 4.3.5 and 4.3.6 in descending order of TETRA user market
importance as judged by the 2001 questionnaire panel, other clauses under clause 4.3 are in no specific order of
importance.
4.3.2 Improved battery operating life for daily PMR shift use
Improved battery operating life is a very important user requirement in all market segments and in all user
organizations. Improved battery operating life for daily PMR shift use is the most important user requirement in the
general TETRA market.
In PMR, the majority of the calls are group calls. These calls happen at a high frequency and are very short (compared
with individual calls).
Increasing call setup time or losing fragments of speech is unacceptable for Public Safety users. The network should in
the first place be always available and reliable. "Sleeping" terminals would probably not meet those requirements.
Discontinuous Transmission (DTX) will probably bring almost no improvement for PMR users since they release the
PTT when not talking. It would probably also be unacceptable for Public Safety users because it could compromise the
use of "ambience listening" (used in emergency calls).
Note that, even if it is found that techniques such as DTX and energy economy mode are not beneficial for some types
of PMR users, it should be straightforward for these features to be disabled for these users. The function could
potentially even be de/activated according to the profile of the individual user.
4.3.3 Improved battery operating life for telephony use
Improved battery operating life for telephony use was in 2001 seen as the second most important user requirement in
the general TETRA market. It was seen as more or equal important to improved battery operating life for daily PMR
shift use by the utility and PAMR type users. For Public Safety users this aspect had the lowest priority.
For telephony use (calls are longer and less frequent compared with PTT type calls) increased call setup is less
noticeable and as such not considered as a problem.
For this type of use "sleeping" terminals and DTX could be very beneficial and acceptable for all users.
4.3.4 Improved battery operating life for data use
With the introduction of HSD in Release 2 and improvements in Release 2.1 the use of mobile data will move to
become a real alternative for commercial cellular mobile services, with the extra benefit from TETRA's inbuilt security
and other services. This change in operations will enable the users to use more complex data applications on their
TETRA devices than before.
Even moderate increase in data use places a significant extra burden on batteries that should be taken into account,
noting that even when the device is not sending or receiving data, the user may be using the device to fill in fields, look
at the pictures, etc. typically with the screen lit up, all of which requires power. In these situations the terminal is often
out of its (protective) holder and there is a greater chance for utilising solar energy than in normal holder-based voice
communication cases, which could be a partial solution for extending the battery life. However, the batteries should also
provide a reasonable working cycle during night shifts and other cases where solar energy is not a viable option.
For example, Automatic Person Location (APL) services (see clause 4.4) place a burden for portable radio equipment,
both when calculating and keeping track of the location and when communicating with the location server over the air.
APL is normally done transparently to the user of the radio, i.e. the user does not need to do anything, nor can he do
anything to prevent the battery drain except to turn the device/APL service off.
ETSI
14 ETSI TR 102 021-4 V1.4.1 (2011-08)
4.3.5 Weight reduction
In the general TETRA market in 2001 this requirement was far less important than improved battery operating life. For
Public Safety users however this requirement was second on the requirement list when the user requirements were
gathered for Release 2, not so far behind the requirement for improved battery operating life for daily PMR shift use.
However, the developments in this area since then have reduced the importance of this area.
4.3.6 Size reduction
In the general TETRA market this requirement had the lowest priority in 2001. For Public Safety users however this
requirement was seen during the Release 2 URS work as more important than improved battery operating life for
telephony use. As the terminal sizes have come down since then, (further) size reduction is seen by Public Safety as less
important for Release 2.1 than it was for Release 2.
However, new markets where TETRA competes against other technologies have identified a need for further size
reduction based on requests from their customer base.
4.3.7 Co-existence of terminals (MSs) and/or base stations (BSs)
TETRA terminal user experiences from several countries have shown that some TETRA terminals have difficulties to
operate in close vicinity of each other. These terminals however comply with the current TETRA specifications.
TETRA specifications should be tightened to allow closer co-existence between MSs.
Transmitting terminals in close vicinity of some receiving terminals seem to degrade the reception of those receiving
terminals, sometimes to the extent that the connection with the network is lost. These terminals could operate in
uncorrelated communication, e.g. they do not communicate with each other but with third parties not in close vicinity.
The degraded receiving terminal could also be in idle mode.
The behaviour of those degrading receiving terminals is a problem for the users in the public safety community. They
need reliable terminals in all of their normal operational conditions. The current terminal behaviour could cause loss of
lives in critical situations.
Typical scenarios of these normal operational conditions are given as examples.
Scenario 1: radio users in the same car
Two or more policemen (uniformed or secret) often operate while they are in the same car using portable radios. Each
of them needs the possibility to communicate independently of the others, at the same time, in a group call, individual
call, simplex call or duplex call.
Scenario 2: radio users at the same table
Two or more radio users (commanding officers of different organizations) meet during crisis management around the
same table. They have put their portable radios in front of themselves on the meeting table. Their radios are involved in
uncorrelated communication, e.g. they normally do not communicate with each other using their radios but
communicate with third parties not in close vicinity. Their radios could also be in idle mode. At any moment all of them
should be able to communicate independently of the others, at the same time, in a group call, individual call, simplex
call or duplex call.
There is therefore a user requirement for terminals to operate located in close proximity to each other (e.g. when the
ter
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