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Package of approved ITU-R recommendations on RNSS systems
All these ITU-R recommendations provide characteristics and protection criteria for generic types of RNSS receiving earth and space stations |
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The ITU Membership considered and approved a package of eight ITU-R Recommendations on radionavigation-satellite service (RNSS) systems as listed below.
Recommendation ITU-R M.1787-3 – Description of systems and networks in the radionavigation-satellite service (space-to-Earth and space-tospace) and technical characteristics of transmitting space stations operating in the bands 1 164-1 215 MHz, 1 215- 1 300 MHz and 1 559-1 610 MHz
The information on orbital parameters, navigation signals and technical characteristics of systems and networks in the radionavigation-satellite service (RNSS) (space-to-Earth, space-to-space) operating in the bands 1 164-1 215 MHz, 1 215-1 300 MHz, and 1 559-1 610 MHz are presented in this Recommendation. This information is intended for use in the assessment of the interference impact between systems and networks in the RNSS and with other services and systems.
Recommendation ITU-R M.1901-1 – Guidance on ITU-R Recommendations related to systems and networks in the radionavigation-satellite service operating in the frequency bands 1 164-1 215 MHz, 1 215-1 300 MHz, 1 559-1 610 MHz, 5 000-5 010 MHz and 5 010-5 030 MHz
This Recommendation is intended to provide guidance on other ITU-R Recommendations related to the technical characteristics and protection criteria of radionavigationsatellite service (RNSS) receiving earth stations and characteristics of RNSS transmitting space stations planned or operating in the frequency bands 1 164-1 215 MHz, 1 2151 300 MHz, 1 559-1 610 MHz, 5 000-5 010 MHz and 5 010-5 030 MHz. In addition, this Recommendation gives a brief overview of those Recommendations.
Recommendation ITU-R M.1902- 0 – Characteristics and protection criteria for receiving earth stations in the radionavigation-satellite service (space-to-Earth) operating in the band 1 215-1 300 MHz
Characteristics and protection criteria for radionavigation-satellite service (RNSS) receiving earth stations operating in the band 1 215-1 300 MHz are presented in this Recommendation. This information is intended for performing analyses of radio-frequency interference impact on RNSS (space-to-Earth) receivers operating in the band 1 215-1 300 MHz from radio sources other than in the RNSS.
Recommendation ITU-R M.1903- 0 – Characteristics and protection criteria for receiving earth stations in the radionavigation-satellite service (space-to-Earth) and receivers in the aeronautical radionavigation service operating in the band 1 559-1 610 MHz
Characteristics and protection criteria for radionavigation-satellite service (RNSS) receiving earth stations and aeronautical radionavigation service (ARNS) receiving stations operating in the band 1 559-1 610 MHz are presented in this Recommendation. This information is intended for performing analyses of radiofrequency interference impact on RNSS (space-to-Earth) and ARNS receivers operating in the band 1 559-1 610 MHz from radio sources other than in the RNSS.
Recommendation ITU-R M.1904-0 – Characteristics, performance requirements and protection criteria for receiving stations of the radionavigation-satellite service (space-to-space) operating in the frequency bands 1 164-1 215 MHz, 1 215-1 300 MHz and 1 559-1 610 MHz
The characteristics and protection criteria for radionavigation-satellite service (RNSS) spaceborne receivers are presented in this Recommendation. This information is intended for performing analyses of radio-frequency interference impact on RNSS receivers operating space-tospace in the bands 1 164-1 215 MHz, 1 215-1 300 MHz and 1 559-1 610 MHz from emissions of non-RNSS sources.
Recommendation ITU-R M.1905- 0 – Characteristics and protection criteria for receiving earth stations in the radionavigation-satellite service (space-to-Earth) operating in the band 1 164-1 215 MHz
Characteristics and protection criteria for radionavigation-satellite service (RNSS) receiving earth stations operating in the band 1 164-1 215 MHz are presented in this Recommendation. This information is intended for performing analyses of radio-frequency interference impact on RNSS (space-to-Earth) receivers operating in the band 1 164-1 215 MHz from radio sources other than in the RNSS.
Recommendation ITU-R M.1906- 1 – Characteristics and protection criteria of receiving space stations and characteristics of transmitting earth stations in the radionavigation-satellite service (Earth-to-space) operating in the band 5 000-5 010 MHz
Characteristics and protection criteria for radionavigation-satellite service (RNSS) receiving space stations, and characteristics of RNSS transmitting earth stations, planned or operating in the band 5 000-5 010 MHz are presented in this Recommendation. This information is intended for performing analyses of radio-frequency interference impact on systems and networks in the RNSS (Earthto- space) operating in this band from radio sources other than in the RNSS.
Recommendation ITU-R M.2031- 1 – Characteristics and protection criteria of receiving earth stations and characteristics of transmitting space stations of the radionavigation-satellite service (space-to-Earth) operating in the band 5 010-5 030 MHz
Characteristics and protection criteria for radionavigation-satellite service (RNSS) receiving earth stations, and characteristics of RNSS transmitting space stations planned or operating in the band 5 010-5 030 MHz are presented in this Recommendation. This information is intended for performing sharing and compatibility analyses of radio-frequency interference impact on systems and networks in the RNSS (spaceto-Earth) operating in the band 5 010-5 030 MHz from radio sources other than in the RNSS.
As mentioned above, all these ITU-R recommendations provide characteristics and protection criteria for generic types of RNSS receiving earth and space stations as well as transmission characteristics of all RNSS systems and networks in the bands 1 164-1 215 MHz, 1 215-1 300 MHz, 1 559-1 610 MHz, 5 000-5 010 MHz and 5 010-5 030 MHz, some with safety of life service provisions. All these ITU-R recommendations are freely accessible online at http://www.itu.int/rec/R-REC-M/ en. The related studies are continuously evolving based on contributions to and participation at the meetings of ITU-R Working Party 4C, the responsible group where all the related work is currently being conducted, so that those ITU-R recommendations can always reflect the most recent developments related to systems and networks in the RNSS.
Timing aspect of GNSS and its critical importance
Systems and networks in the radionavigation-satellite service (RNSS) provide worldwide accurate information for many positioning, navigation and timing applications, including safety aspects for some frequency bands. The RNSS continues to evolve, as new systems come on line and additional applications are developed.
Global Navigation Satellite Systems (GNSS) operate in the RNSS, and in particular in frequency bands allocated to that service, and provide coverage on and above the entire Earth’s surface. Examples of GNSS systems include China’s Compass/Beidou system, Europe’s Galileo system, Russia’s Global Navigation Satellite System (GLONASS) and USA’s Global Positioning Satellite (GPS) system.
Although the globally installed base of RNSS devices is greatly dominated by smartphones, followed a distant second by automobiles, the number of RNSS devices in use for professional applications continues to grow and serve a critical role in national economies, public safety, science, etc. Billions of people globally benefit from these high-end RNSS devices on a day-to-day basis, e.g. enjoying the produce of sustainable and cost-effective agriculture, using efficiently coordinated transport networks, and leveraging RNSSsynchronized telecommunication networks.
RNSS receivers measure radionavigation signals delivered by satellite. They are very different from receivers used in radiocommunications systems, where the incoming message is not known to the receiving device whose goal is to find the message and determine whether each signal bit is a one or a zero using sophisticated methods to correct errors. The RNSS incoming signal sequence (ones and zeros) is known to the RNSS receiver. The primary measurement in RNSS systems is the precise timing of bit transitions in the navigation signal. Precise positioning requires subnanosecond measurement of bit edges and effective multipath rejection. Both, in turn, require wide receiver bandwidth.
The extreme precision in the clocks required for accurate positioning can be transferred to an RNSS timing receiver and utilized wherever accurate frequency or absolute time is required. RNSS timing is used across a range of civilian and government activities due to its ability to reliably transfer precise time synchronization to global standards over very large distances with low-cost, very low maintenance user equipment.
RNSS provides precise timing and synchronization for most critical infrastructures. Telecommunication networks use the RNSS timing function for handover between base stations in wireless communications, time slot management and event logging. The main applications are:
▪ Satellite Communications,
▪ Professional Mobile Radio,
▪ Digital Cellular Network,
▪ Public Switched Telephone Network.
Telecommunication networks are continuously evolving toward higher capacity, increased transmission speeds and exploitation of higher frequencies. Consequently, the request for timing and synchronization requirements continuously gets more demanding.
Power grids use RNSS timing in systems providing measurements relevant to the network status. Smart grid development is underway all over the world. Phasor Measurement Units (PMUs) are pivotal to the development of network automatic protection systems. PMUs are deployed across remote locations of power networks requiring microsecond-level accuracy. The internal time references are currently based on RNSS receivers.
The finance sector, i.e. banks and Stock Exchanges, uses RNSS to timestamp financial transactions, allowing tracing of causal relationships and synchronizing financial computer systems. The main applications are financial transaction timestamps.
There is an increased RNSS interest for small cells synchronisation. Small cells are low-powered radio access nodes that operate in licensed and unlicensed spectrum that have a range between several meters up to 1 or 2 kilometres. Small cell base stations can be deployed at street-level or within buildings and are key elements of the LTE deployment. The small cells market is therefore growing very rapidly to support the need for greater coverage and increasing mobile broadband traffic. LTE small cells networks synchronisation can rely on RNSS. This is a potentially promising RNSS market as the outdoor small cells market is expected to grow by 43% CAGR from now until 2020.
The timing and synchronisation community is facing many challenges linked to an increased need for resilience, reliability and security. The frequency and severity of threats to RNSS systems is evolving from unstructured experiments to more organised attacks that are better funded and more motivated. The technology to disrupt RNSS has become much more accessible. Examples include increases in websites selling low-cost “personal protection” jammers and GPS starting to gain attention at hacker conventions.
Some RNSS systems use coordinated universal time (UTC) while others operate independent of UTC by using their own internal time, i.e. a continuous time scale.
A UTC change (i.e. use of a continuous reference time scale) may not have significant impacts or consequences on the operation of RNSS systems that use a continuous time scale, but will affect the operation of RNSS systems that use UTC. With this it should be noted that the RNSS systems disseminate time signals used for navigation and for synchronization of other radiocommunication systems, especially navigation applications associated with safety (for example, usage of the navigation signals for aircraft approaching a runway). There is wide usage of RNSS systems all over the world and a large amount of the current equipment employs various synchronization procedures. Taking this into account, if the UTC change is implemented there are possible negative consequences to the operation of some existing services and systems of the RNSS.
In case of UTC change, some RNSS systems would require update/change. However, in some cases, for example, spaceborne receivers, it is not feasible to modify the navigation equipment throughout the operational life. The necessary updates and changes will lead to high financial expenditures and also require update of all authorized technical documents, carrying out of complete cycle of retests and recertification of these systems and objects (for example, aircrafts, launch vehicles, etc.).
In case of the change of UTC, from the technical point of view, the duration of the required transition time period for those affected operating RNSS systems to be modified is at least 10 years. However, the actual duration of the required transition time period will depend on the financial, legal and arrangement consequences which can significantly extend this period (more than 10 years) and will be individual for each State.
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