MSS Spectrum Archives from 2000
Spectrum requirements of mobile-satellite services
Ram Manohar
Manager, Spectrum
Inmarsat
Growth in mobile-satellite services
Demand for mobile-satellite services (MSS) has grown tremendously over the last decade or so. Until the early 1990s, only Inmarsat and the Russian Volna satellite networks provided mobile satellite communication services, mainly to ships. Inmarsat soon added aeronautical and land mobile satellite services to its portfolio of services.
In the mid-1990s, the world witnessed the emergence of four more land mobile satellite service systems in Australia, the United States, Canada, and Mexico in addition to Inmarsat’s 3rd generation system.
All these systems use geostationary (GSO) Satellites that operate in the limited MSS allocations (33 MHz) in the L-band (1.5-1.6 GHz) and provide voice and low bit-rate data services to mobile earth stations.
In recognition of the growing needs of mobile-satellite services, the 1992 World Administrative Radio Conference (WARC-92) made additional spectrum allocations for MSS. A number of administrations drew up plans to implement geostationary, as well as non-geostationary mobile-satellite service (non-GSO MSS) systems in these bands. Two non-GSO systems, Iridium and Globalstar, even started offering services in the 1.6-2.4 GHz MSS bands.
Another non-GSO system, ICO, is to start commercial operations in the 2 GHz MSS bands in a couple of years. These satellites were designed to provide voice and low bit-rate data services to handheld mobile user terminals.
Several other administrations continued to be attracted to the good old L-band and planned to implement their MSS systems in the 1.5-1.6 GHz.
In February 2000, Indonesia launched its state-of-the-art L-band geostationary satellite, Garuda, and the United Arab Emirates is to launch its equally powerful satellite Thuraya.
These satellites were also originally designed to provide voice and low bit-rate data services to handheld mobile user terminals.
Recently, Inmarsat decided to implement two of its 4th Generation Satellites in the L-band to provide broadband multimedia and Internet data services to palmtop mobile user terminals (see Figure 1).
These services are defined as a part of the IMT-2000 range of services and the Satellite Systems will constitute the satellite component of IMT-2000."
MSS Spectrum Allocations
In spite of the explosive growth in both the range and volume of mobile-satellite services worldwide, spectrum allocations in this arena have not been commensurate with that growth.
The original allocations of 2 x 23.5 MHz in the 1.5-1.6 GHz for the maritime mobile satellite service (MMSS) and the aeronautical mobile satellite (R) service AMS(R)S were made in 1971.
Some minor adjustments were made to these allocations by WARC-79, resulting in a total of 29 MHz of space-to-Earth (i.e. downlink) and 34 MHz of Earth-to-space (i.e. uplink) allocations to the MMSS and AMS(R)S.
WARC-87 made further changes to permit land mobile satellite services in some parts of these allocations, albeit maintaining a status quo with regard to the allocations themselves.
WARC-92 harmonized the uplink and downlink allocations in the L-band to 2 x 34 MHz and made additional MSS allocations of 2 x 16.5 MHz in the 1.6-2.4 GHz and of 2 x 30 MHz in the 1.9-2.1 GHz bands, the latter only being available from 2005.
In addition, WARC-92 adopted a Resolution (what has become Resolution 213 today) requesting ITU-R to study the feasibility of making additional MSS allocations in some segments of the L-band.
WRC-95 lifted the access date constraints on the 1.9-2.1 GHz MSS allocations and made some minor changes to the so-called ‘Region 2 only’ allocations in these bands.
WRC-97 made the MSS allocations in the L-band generic, but following an extensive debate, this conference called for further study, deferring the matter to WRC-2000 for consideration.
So, clearly, the subject of additional MSS requirements has been studied extensively within ITU-R for many years.
In addition, every Conference Preparatory Meeting (CPM) has made recommendations on the matter. Yet, as can be seen from this analysis, the problem remains unresolved.
Meanwhile, MSS spectrum allocations in the L-band, in particular, are nearing congestion fast and urgently need some relief.
MSS spectrum issues at WRC-2000
Three items on the agenda of WRC-2000 (namely, items 1.6, 1.9, and 1.10) inherently deal with the question of MSS spectrum requirements.
The 1999 report of the CPM includes clear conclusions of ITU-R’s work on the various aspects surrounding MSS spectrum allocations and their usage. This article highlights some of them.
IMT-2000
One of the conclusions of the CPM report concerns spectrum requirements for the satellite component of IMT-2000, which is to be accommodated in the MSS allocations (Chapter 1, Part B.2).
To meet the requirements of this component, the total MSS Spectrum allocations would need to be 2 x 123 MHz by 2005 and 2 x 145 MHz by 2010, says the report.
On this basis, and taking into account all the regional variations in the MSS spectrum allocations available, it can be concluded that the MSS will suffer spectrum shortfalls of at least 2 x 8 MHz by 2005 and 2 x 30 MHz by 2010.
Feasibility of making MSS downlink allocations in 1559-1567 MHz band
The report also addresses the question of sharing between MSS downlink allocations and the radionavigation-satellite service, or RNSS (Chapter 2, Section 2.2.1).
Even though the studies conducted by ITU-R were not unanimous on the protection of, or non-protection of, the existing Global Positioning Satellite (GPS) system, the overall conclusion is that such an allocation can not be made on account of the anticipated requirements of the Global Navigation Satellite System (GNSS). Thus, it is not possible to extend MSS downlink allocations in the L-band upwards of 1559 MHz.
Another summary in the report points to the positive conclusion of ITU-R work on the feasibility of making MSS uplink allocations in parts of the 1675-1710 MHz band in response to Resolution 213 (Chapter 2, Section 2.2.2). The report identifies 1683-1690 MHz as the preferred sub-band for making additional worldwide MSS uplink allocations in the L-band.
Generic MSS allocations in the L-band
The salient message from ITU-R’s work on this subject, in response to Resolution 218, is that the airline industry wants assured access to at least 10 MHz of the L-band spectrum in the erstwhile AMS(R)S bands for their distress and safety services (Chapter 2, Section 2.1). This industry projects its year 2010 requirements for AMS(R)S to be about 2 x 11 MHz.
Similarly, the maritime industry wants assured access to spectrum for its distress and safety services under the Global Maritime Distress and Safety System (GMDSS), as presently indicated in the Radio Regulations (provision S5.353A).
These spectrum demands of aeronautical and maritime distress and safety services tantamount to additional pressure on overall MSS spectrum resources.
Other related extracts from the CPM-99 Report
In a general discussion of the MSS spectrum requirements in the 1-3 GHz range (Chapter 2, Part A), the report urges administrations to make every effort to find a suitable MSS downlink allocation. They would do so taking into account the results of ITU-R’s sharing studies, in case a downlink in the 1559-1567 MHz band does not prove feasible.
The net thrust of CPM-99 recommendations
The arguments, put forward in the CPM report, on the spectrum situation for MSS can be collated and summarized as follows:
There is an established requirement of 2 x 8 MHz of additional MSS spectrum by 2005.
The projected requirements of AMS(R)S and GMDSS further worsen the MSS spectrum congestion situation.
It has been established that it is feasible to make MSS uplink allocations of 7 MHz worldwide by extending the 1683-1690 MHz Region 2 only allocation to Regions 1 and 3.
It has been established that a matching MSS downlink allocation in the 1559-1567 MHz would not be feasible.
As stated earlier, the MSS spectrum allocations in the L-band have seen the largest usage ever, with the bands now almost reaching a congestion point. Resolution 213 was primarily aimed at making additional MSS allocations in or near the L-band.
A lot of work has been done in ITU-R on this, and the task under Resolution 213 can indeed be accomplished with a little more effort. As it has not been possible to recommend downlink allocations in the GNSS bands, it is imperative for us to find an alternative 7 MHz for an MSS downlink allocation.
Why can’t we follow the example of the MSS uplink case and extend the existing Region 2 only allocations, on a limited basis, to Regions 1 and 3 for MSS downlinks as well?
The 1518-1525 MHz segment, which is part of a larger band already allocated to MSS downlinks in Region 2, could form a matching downlink in response to Resolution 213.
The feasibility of sharing MSS downlinks with other co-primary radio services in this band has already been studied and concluded upon by ITU-R.
So, only a small amount of spectrum is being sought for MSS downlinks in this range where other co- primary services have much larger allocations. Such an allocation would go a long way in improving the long-drawn-out shortage of MSS spectrum worldwide.
Conclusion
Over the last decade, the increasing interest in MSS has been clearly evident through the growing number of filings in the Radiocommunication Bureau for GSO MSS and non-GSO MSS systems from various ITU administrations.
The need for additional MSS spectrum allocations is hardly surprising, particularly in view of the fact that the total existing MSS allocations are small compared with those of other radiocommunication services.
ITU has, for a long time, advocated globally harmonized frequency allocations.
Thus, the regional imbalances in the Table of Frequency Allocations (Article 5 of the Radio Regulations) should point a way to making these additional MSS allocations.
Extending the Region 2 only allocations of the 1683 -1690 MHz band for MSS uplinks and the 1518 -1525 MHz band for MSS downlinks to Regions 1 and 3, at WRC-2000, would enable administrations to almost completely satisfy the projected needs of their mobile-satellite users up to 2005
In spite of the explosive growth in both the range and volume of mobile-satellite services worldwide, spectrum allocations in this arena have not been commensurate with that growth.
The original allocations of 2 x 23.5 MHz in the 1.5-1.6 GHz for the maritime mobile satellite service (MMSS) and the aeronautical mobile satellite (R) service AMS(R)S were made in 1971.
Some minor adjustments were made to these allocations by WARC-79, resulting in a total of 29 MHz of space-to-Earth (i.e. downlink) and 34 MHz of Earth-to-space (i.e. uplink) allocations to the MMSS and AMS(R)S.
WARC-87 made further changes to permit land mobile satellite services in some parts of these allocations, albeit maintaining a status quo with regard to the allocations themselves.
WARC-92 harmonized the uplink and downlink allocations in the L-band to 2 x 34 MHz and made additional MSS allocations of 2 x 16.5 MHz in the 1.6-2.4 GHz and of 2 x 30 MHz in the 1.9-2.1 GHz bands, the latter only being available from 2005.
In addition, WARC-92 adopted a Resolution (what has become Resolution 213 today) requesting ITU-R to study the feasibility of making additional MSS allocations in some segments of the L-band.
WRC-95 lifted the access date constraints on the 1.9-2.1 GHz MSS allocations and made some minor changes to the so-called ‘Region 2 only’ allocations in these bands.
WRC-97 made the MSS allocations in the L-band generic, but following an extensive debate, this conference called for further study, deferring the matter to WRC-2000 for consideration.
So, clearly, the subject of additional MSS requirements has been studied extensively within ITU-R for many years.
In addition, every Conference Preparatory Meeting (CPM) has made recommendations on the matter. Yet, as can be seen from this analysis, the problem remains unresolved.
Meanwhile, MSS spectrum allocations in the L-band, in particular, are nearing congestion fast and urgently need some relief.
MSS spectrum issues at WRC-2000
Three items on the agenda of WRC-2000 (namely, items 1.6, 1.9, and 1.10) inherently deal with the question of MSS spectrum requirements.
The 1999 report of the CPM includes clear conclusions of ITU-R’s work on the various aspects surrounding MSS spectrum allocations and their usage. This article highlights some of them.
IMT-2000
One of the conclusions of the CPM report concerns spectrum requirements for the satellite component of IMT-2000, which is to be accommodated in the MSS allocations (Chapter 1, Part B.2).
To meet the requirements of this component, the total MSS Spectrum allocations would need to be 2 x 123 MHz by 2005 and 2 x 145 MHz by 2010, says the report.
On this basis, and taking into account all the regional variations in the MSS spectrum allocations available, it can be concluded that the MSS will suffer spectrum shortfalls of at least 2 x 8 MHz by 2005 and 2 x 30 MHz by 2010.
Feasibility of making MSS downlink allocations in 1559-1567 MHz band
The report also addresses the question of sharing between MSS downlink allocations and the radionavigation-satellite service, or RNSS (Chapter 2, Section 2.2.1).
Even though the studies conducted by ITU-R were not unanimous on the protection of, or non-protection of, the existing Global Positioning Satellite (GPS) system, the overall conclusion is that such an allocation can not be made on account of the anticipated requirements of the Global Navigation Satellite System (GNSS). Thus, it is not possible to extend MSS downlink allocations in the L-band upwards of 1559 MHz.
Another summary in the report points to the positive conclusion of ITU-R work on the feasibility of making MSS uplink allocations in parts of the 1675-1710 MHz band in response to Resolution 213 (Chapter 2, Section 2.2.2). The report identifies 1683-1690 MHz as the preferred sub-band for making additional worldwide MSS uplink allocations in the L-band.
Generic MSS allocations in the L-band
The salient message from ITU-R’s work on this subject, in response to Resolution 218, is that the airline industry wants assured access to at least 10 MHz of the L-band spectrum in the erstwhile AMS(R)S bands for their distress and safety services (Chapter 2, Section 2.1). This industry projects its year 2010 requirements for AMS(R)S to be about 2 x 11 MHz.
Similarly, the maritime industry wants assured access to spectrum for its distress and safety services under the Global Maritime Distress and Safety System (GMDSS), as presently indicated in the Radio Regulations (provision S5.353A).
These spectrum demands of aeronautical and maritime distress and safety services tantamount to additional pressure on overall MSS spectrum resources.
Other related extracts from the CPM-99 Report
In a general discussion of the MSS spectrum requirements in the 1-3 GHz range (Chapter 2, Part A), the report urges administrations to make every effort to find a suitable MSS downlink allocation. They would do so taking into account the results of ITU-R’s sharing studies, in case a downlink in the 1559-1567 MHz band does not prove feasible.
The net thrust of CPM-99 recommendations
The arguments, put forward in the CPM report, on the spectrum situation for MSS can be collated and summarized as follows:
There is an established requirement of 2 x 8 MHz of additional MSS spectrum by 2005.
The projected requirements of AMS(R)S and GMDSS further worsen the MSS spectrum congestion situation.
It has been established that it is feasible to make MSS uplink allocations of 7 MHz worldwide by extending the 1683-1690 MHz Region 2 only allocation to Regions 1 and 3.
It has been established that a matching MSS downlink allocation in the 1559-1567 MHz would not be feasible.
As stated earlier, the MSS spectrum allocations in the L-band have seen the largest usage ever, with the bands now almost reaching a congestion point. Resolution 213 was primarily aimed at making additional MSS allocations in or near the L-band.
A lot of work has been done in ITU-R on this, and the task under Resolution 213 can indeed be accomplished with a little more effort. As it has not been possible to recommend downlink allocations in the GNSS bands, it is imperative for us to find an alternative 7 MHz for an MSS downlink allocation.
Why can’t we follow the example of the MSS uplink case and extend the existing Region 2 only allocations, on a limited basis, to Regions 1 and 3 for MSS downlinks as well?
The 1518-1525 MHz segment, which is part of a larger band already allocated to MSS downlinks in Region 2, could form a matching downlink in response to Resolution 213.
The feasibility of sharing MSS downlinks with other co-primary radio services in this band has already been studied and concluded upon by ITU-R.
So, only a small amount of spectrum is being sought for MSS downlinks in this range where other co- primary services have much larger allocations. Such an allocation would go a long way in improving the long-drawn-out shortage of MSS spectrum worldwide.
Conclusion
Over the last decade, the increasing interest in MSS has been clearly evident through the growing number of filings in the Radiocommunication Bureau for GSO MSS and non-GSO MSS systems from various ITU administrations.
The need for additional MSS spectrum allocations is hardly surprising, particularly in view of the fact that the total existing MSS allocations are small compared with those of other radiocommunication services.
ITU has, for a long time, advocated globally harmonized frequency allocations.
Thus, the regional imbalances in the Table of Frequency Allocations (Article 5 of the Radio Regulations) should point a way to making these additional MSS allocations.
Extending the Region 2 only allocations of the 1683 -1690 MHz band for MSS uplinks and the 1518 -1525 MHz band for MSS downlinks to Regions 1 and 3, at WRC-2000, would enable administrations to almost completely satisfy the projected needs of their mobile-satellite users up to 2005
Source of MSS Spectrum Post
http://www.itu.int/newsarchive/wrc2000/presskit/PositionPaper_MSS_Inmarsat.html
http://www.itu.int/newsarchive/wrc2000/presskit/PositionPaper_MSS_Inmarsat.html
Note Inmarsat Key Player.. ICO, TerreStar, Lightsquared,
