ETSI TS 103 246-2 V1.2.1 (2017-03)

Satellite Earth Stations and Systems (SES); GNSS based location systems; Part 2: Reference Architecture

RTS/SES-00407

General Information

• Status: Published
• Publication Date: 05-Mar-2017
• Technical Committee: SES SCN - Satellite Communications and Navigation
• Current Stage: 12 - Completion
• Due Date: 01-Mar-2017
• Completion Date: 06-Mar-2017
• Mandate: M/496

Standards Content (Sample)

TECHNICAL SPECIFICATION
Satellite Earth Stations and Systems (SES);
GNSS based location systems;
Part 2: Reference Architecture

2 ETSI TS 103 246-2 V1.2.1 (2017-03)

Reference
RTS/SES-00407
Keywords
architecture, GNSS, location, MSS, navigation,
receiver, satellite, system, terminal

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3 ETSI TS 103 246-2 V1.2.1 (2017-03)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 10
4 Requirements for GNSS-based Location Systems . 11
5 GBLS Architecture (Level 1) . 12
5.1 Level 1 architecture functional blocks and logical interfaces . 12
5.2 External Functional Blocks . 14
5.2.1 GNSS and Other External Systems . 14
5.2.1.1 GNSS . 14
5.2.1.2 Other External Systems . 14
5.2.3 Application(s) . 14
5.3 GBLS Functions . 15
5.4 GBLS External Interfaces. 15
6 GBLS Architecture (Level 2) . 15
6.1 Level 2 architecture mandatory and optional components . 15
6.1.1 General . 15
6.1.2 GBLS architecture with Target Positioning Module only . 17
6.1.3 GBLS architecture with Target Positioning Module and Central Facility . 18
6.2 Positioning Module (PM) . 19
6.2.1 Sensor Management . 19
6.2.2 On-board Position Calculation Module (OBPCM) . 19
6.2.3 Application Interface Module . 19
6.3 Central Facility (CF) . 19
6.3.1 Centralized Position Calculation Module (CPCM) . 19
6.3.2 Central Management Module (CMM) . 19
6.3.3 Application Interface Module . 20
6.4 Core Interface . 20
7 GBLS Architecture (Level 3) . 21
7.1 Level 3 detailed architecture . 21
7.1.1 Generic GBLS . 21
7.2 Functional Block Definitions . 21
7.2.1 List of functional blocks . 21
7.2.2 GNSS Sensor . 22
7.2.3 Telecommunication Module . 22
7.2.4 Inertial Sensor . 23
7.2.5 Magnetometer . 23
7.2.6 Odometer . 23
7.2.7 Beam Forming Antenna . 23
7.2.8 EMI Mitigation . 23
7.2.9 EMI Localization . 23
7.2.10 Location Hybridization Algorithm . 24
7.2.11 Integrity Building Algorithm . 24
7.2.12 PPP Module . 24
7.2.13 D-GNSS/RTK processing module . 24
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4 ETSI TS 103 246-2 V1.2.1 (2017-03)
7.2.14 Location Authentication . 25
7.2.15 Security Provisioning . 25
7.2.16 Security Verification . 26
7.2.17 Privacy Provisioning . 26
7.2.18 Privacy Test . 26
7.2.19 Application Interface Module . 26
7.2.20 Reference Receivers . 26
7.2.21 Assistance server . 26
7.2.22 Map database . 27
7.3 Interfaces . 27
Annex A: Void . 29
Annex B (informative): Specific case of GBLS using differential GNSS . 30
B.1 Main use cases . 30
B.2 Impact on GBLS level 2 architecture . 32
B.3 Impact on GBLS Level 3 architecture . 34
Annex C (normative): Assisted GNSS architectures . 42
C.1 Impact on GBLS level 2 . 42
Annex D (informative): Bibliography . 44
History . 45

ETSI
5 ETSI TS 103 246-2 V1.2.1 (2017-03)
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 (https://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 Specification (TS) has been produced by ETSI Technical Committee Satellite Earth Stations and
Systems (SES).
The present document is part 2 of a multi-part deliverable. Full details of the entire series can be found in part 1 [10].
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The increasing expansion of location-based applications aims to satisfy more and more complex and diversified user
requirements: this is highlighted for example by the widespread adoption of multi-functional smart-phones or by the
ever wider adoption of tracking devices (e.g. in transport), etc. This requirement for new and innovative location-based
applications is generating a requirement for increasingly complex location systems.
The wide spectrum of location-based applications identified in [i.1] calls for a new and broader concept for location
systems, taking into account solutions in which GNSS technologies are complemented with other technologies to
improve robustness and performance. The notion of GNSS-based location systems is introduced and defined in this
standard.
Additional clauses and information related to the implementation in GNSS-based location systems of the various
differential GNSS technologies, namely D-GNSS, RTK and PPP are also included in order to facilitate the use of this
set of standards by manufacturers and service providers.
Hence a set of standards for GNSS-based Location systems is defined of which the present document is part 2.

ETSI
6 ETSI TS 103 246-2 V1.2.1 (2017-03)
1 Scope
This multi-part deliverable addresses integrated GNSS based location systems (GBLS) that combine Global Navigation
Satellite Systems (GNSS), with other navigation technologies, as well as with telecommunication networks in order to
deliver location-based services to users. As a consequence the present document is not applicable to GNSS only
receivers.
This multi-part deliverable proposes a list of functional and performance requirements and related test procedures. For
each performance requirement, different classes are defined allowing the benchmark of different GNSS Based Location
Systems (GBLS) addressing the same applications.
The architecture specified herein is a "functional" architecture, meaning that the system is defined in terms of discrete
functional elements connected to other internal or external functional elements via associated "logical" interfaces. These
functional elements and interfaces are derived from service requirements.
The functional architecture is not necessarily related to the "physical architecture" (i.e. the relationship between
equipment which may implement all or some of these functions, and the physical interfaces between them).
The present document can be considered as the Stage 2 functional specification according to the ITU/3GPP approach
[i.4].
2 References
2.1 Normative 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
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://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.
The following referenced documents are necessary for the application of the present document.
th
[1] IS-GPS-200D: "Revision D, Navstar GPS Space Segment/Navigation User Interfaces", March 7 ,
2006.
[2] IS-GPS-705D: "Navstar GPS Space Segment/User Segment L5 Interfaces", September 24, 2013.
[3] IS-GPS-800D: "Navstar GPS Space Segment/User Segment L1C Interfaces", September 24, 2013.
[4] "Galileo OS Signal In Space ICD (OS SIS ICD)", Issue 1.2, EU/GSA.
[5] BDS-SIS-ICD-B1I-2.0 (December 2013): "BeiDou Navigation Satellite System Signal In Space
Interface Control Document Open Service Signal (Version 2.0)".
[6] "Global Navigation Satellite System GLONASS Interface Control Document", Version 5.1, 2008.
[7] IS-QZSS: "Quasi Zenith Satellite System Navigation Service Interface Specifications for QZSS",
st
Version 1.0, July 31 , 2009.
[8] IRNSS SIS ICD For Standard Positioning Service, ISRO-IRNSS-ICD-SPS-1.0.
[9] RTCM 10403.2: "Differential GNSS (Global Navigation Satellite Systems) Services".
[10] ETSI TS 103 246-1: "Satellite Earth Stations and Systems (SES); GNSS based location systems;
Part 1: Functional requirements".
ETSI
7 ETSI TS 103 246-2 V1.2.1 (2017-03)
[11] RTCM 10402.3: "Recommended Standards for Differential GNSS (Global Navigation Satellite
Systems) Service".
[12] RTCM 10401.2: "Standard for Differential Navstar GPS Reference Stations and Integrity Monitors
(RSIM)".
[13] US Department of Transportation, Federal Aviation Administration: "Global Positioning System
st
Wide Area Augmentation System (WAAS) performance Standard" - 1 Edition - 31 October 2008.
NOTE: Available at http://www.gps.gov/technical/ps/2008-WAAS-performance-standard.pdf.
[14] RTCA DO-229D: "Minimum Operational Performance Standards for Global Positioning
System/Satellite-Based Augmentation System Airborne Equipment".
2.2 Informative 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
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
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 103 183: "Satellite Earth Stations and Systems (SES); Global Navigation Satellite
Systems (GNSS) based applications and standardisation needs".
[i.2] ETSI TS 103 246-4: "Satellite Earth Stations and Systems (SES); GNSS based location systems
Part 4: Requirements for location data exchange protocols".
[i.3] ETSI TS 103 246-5: "Satellite Earth Stations and Systems (SES); GNSS based location systems
Part 5: Performance Test specification".
[i.4] Void.
[i.5] M. A. Abdel-Salam: "Precise Point Positioning Using Un-Differenced Code and Carrier Phase
Observations", PH.D. Thesis, Department of Geomatics Engineering, Calgary, Alberta (CAN),
September 2005.
[i.6] ETSI TS 103 246-3: "Satellite Earth Stations and Systems (SES); GNSS based location systems
Part 3: Performance requirements".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Accumulated Delta Range (ADR): Another term for carrier phase measurement.
application module: entity in charge of retrieving from a location system the location-related data associated with one
or more location targets and processing it in order to deliver to the application user the location based service it has been
designed for
NOTE: The application module can be located inside or outside the terminal.
authentication: provision of assurance that the location-related data associated with a location target has been derived
from real and not falsified signals
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8 ETSI TS 103 246-2 V1.2.1 (2017-03)
architecture: abstract representation of a communication system
NOTE: Three complementary types of architecture are defined:
Functional Architecture: the discrete functional elements of the system and the associated logical
interfaces.
Physical (Network) Architecture: the discrete physical (network) elements of the system and the
associated physical interfaces.
Protocol Architecture: the protocol stacks involved in the operation of the system and the
associated peer relationships.
availability: percentage of time that a location system is able to provide the required location-related data
carrier phase measurement: measure of the range between the satellite and receiver expressed in units of cycles of the
carrier frequency
continuity: likelihood that the location system functionality will be available during the complete duration of the
intended operation if the system is operational at the beginning of the operation
D-GNSS: technique aiming at enhancing position accuracy and integrity of a GNSS receiver by using differential
pseudorange corrections and "do not use flag" for faulty satellites delivered by a GNSS reference station located at a
known location
NOTE: In the present document, the term D-GNSS refer to conventional differential GNSS.
electromagnetic interference: any source of RF transmission that is within the frequency band used by a
communication link, which degrades the performance of this link
fraud: any kind of activity of a location-based application stakeholder aiming at jeopardizing the application objective.
GNSS-based location system (GBLS): location system using GNSS as the primary source of positioning
GNSS only receiver: location receiver using GNSS as the unique source of positioning
integrity: measure of the trust in the accuracy of the location-related data provided by the location system and the
ability to provide timely and valid warnings to users when the location system does not fulfil the condition for intended
operation
NOTE: Integrity is expressed through the computation of a protection level. The Integrity function is built to
deliver a warning (or alert) of any to users within a given period of time (time-to-alert).
Related to the Integrity concept, a Loss of Integrity event occurs when an unsafe condition occurs (i.e. a
positioning error higher that the protection level) without annunciation for a time longer than the time-to-
alert limit.
Integrity Monitor (IM): only applicable to conventional D-GNSS. A component of the D-GNSS Reference Station
which is responsible for validating the integrity of the correction computation and broadcast signals
NOTE: When this IM component detects anomalies, it reports these conditions to the Reference Station
component.
jamming: deliberate transmission of interference to disrupt reception of desired signals, which in this case are GNSS or
telecommunication signals
NOTE: Spoofing is considered to be a deceptive form of jamming.
latency: measure of the time elapsed between the event triggering the determination of the location-related data for a
location target and the availability of the location-related data at the user interface
location-based application: application which is able to deliver a service to one or several users, built on the
processing of the location information (location-related data) related to one or several targets
location-related data: set of data associated with a given location target, containing one or more of the following time-
tagged information elements: target position, target motion indicators (velocity and acceleration), and quality of service
indicators (estimates of the position accuracy, reliability or authenticity)
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9 ETSI TS 103 246-2 V1.2.1 (2017-03)
location system: system responsible for providing to a location based application the location-related data of one or
several location targets
location system central facility: centralized logical entity, inside a location system, that gathers the location
information and manages the communication of the location-related data to the application module, which is the
location system external client
location target: physical entity (mobile or stationary) whose position is the focus of the location related data to be built
by the location system
privacy: function of a location system designed to ensure that the location target user's private information (identity,
bank accounts, etc.) and its location-related data cannot be accessed by an unauthorized third party
positioning module: logical entity inside a location target responsible for providing, as a minimum, the relevant
measurements for locating the target
NOTE 1: In some cases, the positioning module will also determine the location of the target and provide the
location related data to the application module. In other cases, it will provide raw measurements to the
location system central facility (enabling it to determine the location target location-related data). In all
case, it includes the group of sensors required to execute these tasks. This group can include navigation
sensors (GNSS, terrestrial beacons, Inertial, Odometers, etc.)
Precise Point Positioning (PPP): differential GNSS technique that uses a worldwide distributed network of reference
stations to provide, in quasi real time, a highly accurate geodetic positioning of a receiver
protection Level (PL): upper bound to the position error such that: P(ε > PL) < I , where I is the Integrity risk and
risk risk
ε is the actual position error
NOTE: The protection level is provided by the location system, and with the integrity risk, is one of the two sub-
features of the integrity system. The protection level is computed both in the vertical and in the horizontal
position domain and it is based on conservative assumptions that can be made on the properties of the
GNSS sensor measurements, i.e. the measurement error can be bounded by a statistical model and the
probability of multiple simultaneous measurement errors can be neglected.
pseudorange: distance between a satellite and a GNSS receiver as estimated by the receiver without correction for the
receiver's time error
NOTE: The prefix "pseudo" highlights the fact that the propagation delay accessible to the receiver encompasses
contributions (such as receiver local clock offset with respect to satellite time) which do not allow it to
determine the actual geometrical distance.
Pseudo Range Correction (PRC): simple difference between a pseudorange measured by a GNSS reference station,
set at a known location and the estimated range between the satellite and this known location
NOTE 1: The estimated range generally uses the computed satellite clock bias correction and may use the estimated
receiver clock bias correction.
NOTE 2: The Pseudo Range Correction represents an estimate of the total GNSS systematic error observed on one
satellite line-of-sight, comprising ionospheric delay, tropospheric delay and orbito-synchro residual error.
It can be directly used in a local area around the reference station to cancel most of the systematic errors.
quality of service: set of indicators that can accompany the location target's position/motion information and is
intended to reflect the quality of the information provided by the location system
NOTE: QoS indicators can include an accuracy estimate, a protection level statistic, the integrity risk, an
authentication flag.
Real Time Kinematic (RTK): particular Differential GNSS technique that provides, in real time, highly accurate
positioning of a target based on carrier phase measurements
NOTE 1: In the RTK context, the target is called the "rover", as opposed to the stationary reference station(s). RTK
makes use of the carrier phase measurements, both in the reference station and in the rover, and this
technique allows the ambiguities affecting these accurate measurements to be resolved.
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10 ETSI TS 103 246-2 V1.2.1 (2017-03)
NOTE 2: If the reference station is at an accurately known location, the rover can compute its accurate geodetic (or
absolute) location. Alternatively, if the reference station's geodetic location is only roughly known, RTK
can still provide high accuracy, but only on a relative and not absolute basis.
reference receiver: receiver placed at a known and surveyed position used for differential GNSS technique
NOTE: A reference receiver is an essential component of a reference station.
reference station: station placed at a known and surveyed position aiming at determining and sharing the systematic
errors of at least one GNSS constellation
NOTE: It can be isolated, and in this case will be integrated in the GBLS, or can be part of a network which itself
can be a part of the GBLS or can be part of the network of an external differential GNSS service provider.
security: function of a location system designed to ensure that the location-related data is safeguarded against
unapproved disclosure or usage inside or outside the location system, and that it is also provided in a secure and reliable
manner that ensures it is neither lost nor corrupted
spoofing: transmission of signals intended to deceive location processing into reporting false target data
terminal-assisted: mode in which the terminal performs only the GNSS measurements (pseudoranges, pseudo Doppler,
etc.) and sends these measurements to a remote central facility where the position calculation takes place
NOTE: This calculation may possibly use additional measurements or data from other sources (GNSS server
assistance, differential GNSS services or non GNSS sensors etc.).
terminal-based: mode in which the terminal performs the GNSS measurements and calculates its own location
NOTE: This calculation may possibly use additional measurements or data from other sources (GNSS server
assistance, differential GNSS services or non GNSS sensors etc.)
time-to-alert: time from when an integrity breach occurs to when an alerting message reaches the user
Time-To-First-Fix (TTFF): time taken by the receiver to produce the first position and time fix whose accuracy is
lower than a defined accuracy limit, starting from the moment the receiver is switched on
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
rd
3GPP 3 Generation Partnership Project
ADR Accumulated Delta Range
A-GNSS Assisted GNSS
AOA Angle Of Arrival
CF Central Facility
CID Call IDentifier
CMM Central Management Module
CPCM Centralized Position Calculation Module
DGNSS Differential GNSS
D-GNSS Differential GNSS
EGNOS European Geostationary Navigation Overlay System
EMA EMI Mitigation Algorithm
EMI Electro-Magnetic Interference
FKP Flächen Korrektur Parameter (German)
GAGAN GPS Aided Geo Augmented Navigation System
GBAS Ground Based Augmentation Systems
GBLS GNSS-based Location System
GEO Geostationary Earth Orbit
GLONASS Global Navigation Satellite System (Russian based system)
GNSS Global Navigation Satellite System
GPS Global Positioning System
GSM Global System for Mobile communications
IBA Integrity Building Algorithm
IM Integrity Monitor
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11 ETSI TS 103 246-2 V1.2.1 (2017-03)
IMU Inertial Measurement Unit
INS Inertial Navigation Sensor
IRNSS Indian Regional Navigation Satellite System
ITS Intelligent Transport Systems
LAAS Local Area Augmentation System
LBS Location-based Services
LHA Location Hybridization Algorithm
LTE Long Term Evolution
M&C Monitoring and Control
MAC Master Auxiliary Corrections
MD Map Database
MSAS Multi-functional Satellite Augmentation System
NRTK Network RTK
OBPCM On-board Position Calculation Module
OTD Observed Time Difference
OTDOA Observed Time Difference Of Arrival
PL Protection Level
PM Positioning Module
PPP Precise Point Positioning
PVT Position, Velocity and Time
QoS Quality of Service
QZSS Quasi-Zenith Satellite System
RF Radio Frequency
RSIM Reference Station Integrity Monitor
RSS Received Signal Strength
RTCM Radio Technical Commission for Maritime Services
RTK Real Time Kinematic
SBAS Satellite Based Augmentation System
SDCM System for Differential Corrections and Monitoring
SNR Signal-to-Noise Ratio
SSR Space State Representation
TDOA Time difference Of Arrival
TOA Time Of Arrival
UHF Ultra High Frequency
VHF Very High Frequency
VRS Virtual Reference Station
WAAS Wide Area Augmentation System
WARTK Wide Area RTK
Wi-Fi Wireless Fidelity
4 Requirements for GNSS-based Location Systems
The Reference Architecture for GNSS-based Location Systems (GBLS), as defined in the following clauses, is derived
from the GBLS Functional Requirements [10] which are intended to provide one or more users with location-related
data (as defined in ETSI TS 103 246-1 [10]) associated with one or more Location Targets. An overview of these
requirements is given below.
The GBLS is intended to be a "generic" location system, and thus to encompass a wide range of functions associated
with GNSS Location-based Services (LBS). The functions defined as "mandatory" form the basis of the GBLS, whilst
the optional functions are also included in the architecture to provide additional choices to allow different architectural
implementations, and additional location-related data to be provided (e.g. GBLS implementing assisted or differential
GNSS techniques).
A particular GNSS-based application may require only a subset of the range of data available in the GBLS architecture.
Therefore a subset of the GBLS architecture, with alternative combinations of subsystems, may only be required for
many applications. For example, the location data provided can range from simple position-reporting in the case of low-
end asset management, to reliable information (e.g. authenticated and with a known uncertainty) and/or high accurate
information on the target's trajectory for liability-critical services such as road charging or Intelligent Transport Systems
(ITS). Some examples of location system implementations (or Implementation Profiles) are given in ETSI
TS 103 246-5 [i.3] where different combinations of architecture elements are subject to testing.
ETSI
12 ETSI TS 103 246-2 V1.2.1 (2017-03)
The functional requirements of the GBLS for location-related data provision are illustrated in Figure 4-1.
mandatory
optional
Provide
location of
Location target(s)
using GNSS
Technological System Policy
Data Delivery
Data content
requirements requirements
requirements
requirements
Multi-
Additional
GNSS
sensor
location-related
Service
M&C Interface
data
Latency
Author-
Security
ization
Hybridi-
Availability Coverage
QoS
Privacy
zation
indicators
Priority
Assisted
Differential
Figure 4-1: GBLS Functional Requirements
Figure 4-1 shows the mandatory and optional functional requirements for the GBLS, grouped into four general
requirement areas. The requirements were derived from a functional analysis of typical GBLS use cases, and are
summarized below:
• Technological requirements: GNSS and, optionally, multi-sensor techniques together with measurement fusion
methods are required to satisfy the range of potential applications. GNSS includes stand-alone positioning, as
well as optional techniques that can improve the performance, for example assisted GNSS and differential
GNSS (WADGNSS, D-GNSS, RTK, NRTK, PPP).
• Data content requirements: the GBLS is required to provide at least location target(s) position(s), and
optionally, additional location-related data (such as speed, acceleration, heading, angular speed and angular
acceleration) and quality of service indicators (such as data accuracy, integrity and authenticity).
• Data delivery requirements: the GBLS is required to implement an external interface conveying location-
related data, and allow monitoring and control of data provisioning (including request priority management).
Optionally, in order to comply with service level requirements when applicable, GBLS could meet pre-defined
availability, coverage and/or latency performance requirements.
• System policy requirements: due to the sensitive nature of the data handled by the GBLS it is required to
implement appropriate privacy protection policy (for the user), authorization policy (to identify authorized
requesting entities) and security policy (protection of sensitive information against disclosure or alteration).
5 GBLS Architecture (Level 1)
5.1 Level 1 architecture functional blocks and logical interfaces
The functional requirements summarized in clause 4 are used in this clause to define mandatory and optional functional
elements to be included in the GBLS Architecture. These elements are grouped into higher level functional blocks with
common features.
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13 ETSI TS 103 246-2 V1.2.1 (2017-03)
In clauses 6 and 7, the GBLS Architecture is defined hierarchically, starting in this clause with the top-level (Leve 1)
overall architecture. In clauses 6 and 7 the architecture is expanded into more detailed Level 2 and 3 architectures. The
definitions in each case are of functional architectures. The Functional Elements (Blocks) required for the production of
location-related data are defined, connected by logical interfaces which define information flows required between the
functional blocks (not necessarily with any relationship to physical interfaces). In addition logical interfaces are also
defined between the GBLS and any external elements. Figure 5-1 depicts the highest level GBLS architecture.

Figure 5-1: GNSS-based Location System (GBLS) Architecture (Level 1)
The functional requirements defined in clause 4 are allocated to the GBLS functional blocks of Figure 5-1 as shown in
Table 5-1.
Table 5-1: GBLS Functional Requirements allocation to GBLS Functional Blocks
Functional Requirement GBLS Functional Block
Sensor Position Central Application Interface

Management Calculation Module Management Module
GNSS X X (optionally)
Multi-Sensor X
Hybridisation X
Additional localization data X X X
QoS indicator X X X X
M&C Interface  X
Availability X X (optionally) X
Priority
Coverage X  X
Latency X  X
Security  X
Privacy  (optionally) X
Service Authorization  (optionally) X
Differential X (optionally)
Assisted X (optionally)
Mandatory
Optional
ETSI
14 ETSI TS 103 246-2 V1.2.1 (2017-03)
In clauses 5.2, 5.3 and 5.4, the elements of Figure 5-1 are described as follows:
• External functional blocks.
• GBLS functions.
• GBLS external interfaces.
NOTE: The Location Target is a physical object (including a person, vehicle, interference source, etc.) associated
with the GBLS, or with external functional blocks, with which sensors or applications interact to provide
its location-related data, but the Location Target is not otherwise specifically defined.
5.2 External Functional Blocks
5.2.1 GNSS and Other External Systems
5.2.1.1 GNSS
The elements defined in this clause and in clause 5.2.1.2 are external to the GBLS, and have interfaces with it.
GNSS provide autonomous geo-spatial positioning with global or regional coverage. The following GNSS systems are
supported in the present document:
• GPS and Modernized GPS [1], [2] and [3]
• Galileo [4]
• BeiDou [5]
• GLONASS [6]
• Quasi-Zenith Satellite System (QZSS) [7]
• Indian Regional Navigation Satellite System [8]
Each GNSS can be used individually or in combination with others. When used in combination, the effective number of
navigation satellite signals available would be increased.
In addition there are regional non-autonomous GNSSs, designed as augmentation systems, aimed at enhancing the
performance of global GNSSs with respect to availability, accuracy and integrity. Among them, the following regional
GNSSs are supported in the present document:
• Satellite Based Augmentation Systems (SBAS), including WAAS, EGNOS, MSAS, and GAGAN.
Some augmentation systems related to GNSS are expected to provide additional external service :
• Commercial or institutional multi applications WADGNSS and (N)RTK, PPP, aeronautical D-GNSS service
provider ([9], [11] and [12]).
• Assisted GNSS solutions.
5.2.1.2 Other External Systems
Other external systems may include:
• Terrestrial telecommunications networks providing position information (e.g. 3G, 4G, Wi-Fi, etc.).
5.2.3 Application(s)
One or more user applications in external systems or subsystems may interface to the GBLS. An application may obtain
location-related data to build value-added services (such as fleet tracking, collision avoidance systems and asset
tracking), with which the user(s) may interact.
ETSI
15 ETSI TS 103 246-2 V1.2.1 (2017-03)
In case the GBLS does not broadcast its location related data on a continuous basis, an application makes a request to
the GBLS for location-related data of one or more location targets, to which the GBLS should reply if security and
privacy requirements are met.
The specification of the application internal logic and its relationship to any external end-user is outside the scope of the
present document.
5.3 GBLS Functions
The overall functions provided by the GBLS are:
• Sensor Management to collect measurement data from the sensors attached to the target and to provide
assistance data.
• Position Calculation that derives and issues the positioning and other parameters of a location target(s) from
the sensor measurements, and possibly from the differential data coming from an external Differential GNSS
service provider or coming from the Central Management.
• Central M
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