1
ACP-WGF15/WP-/
International Civil Aviation Organization
WORKING PAPER / ACP-WGF15/WP-
1 June 2006
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
FIFTEENTH MEETING OF WORKING GROUP F
Cairo, Egypt7-13June 2006
Agenda Item 2: / Review of ITU-R Working Parties 8B and 8DITU Discussions on long-term spectrum availability and protection for the AMS(R)S
(Presented by Y. HASEBE)
(Prepared by Y. SUZUKI)
SUMMARYThis paper presents status of spectrum allocation and activities in ITU-R Study Group 8 on AMS(R)S. It also introduces a new ITU-R Report responding to Res.222 concluding that intersystem real-time pre-emption is not appropriate for the purpose to ensure long term spectrum availability of AMS(R)S and therefore new procedures or methods for this purpose should be developed at the future WRC.
ACTION
WG-F members are invited to consider this paper which is an element of establishing WRC-10 Agenda Item to ensure future spectrum availability for AMS(R)S to be discussed in the WRC-07 Agenda Item 7.2, and to coordinate this issue with their respective Administrations and regional telecommunications organizations.
1. INTRODUCTION
At WRC-97, the sub-bands 1545-1555 MHz (space-to-Earth) and 1646.5-1656.5 MHz (Earth-to-space), which had been exclusively allocated to aeronautical mobile-satellite service (AMS(R)S) providing transmission of messages with priority 1 to 6 in Article 44 of the Radio Regulations were made generic to all MSS with a provision, now numbered 5.357A, to prioritize and protect AMS(R)S. However, as most of this sub-bands were already occupied by non-safety communications and current spectrum requirements of AMS(R)S are not satisfied, it seems to be difficult to expect future long-term and stable spectrum availability for AMS(R)S in these bands under current provisions of the R.R.
This paper introduces problems on current spectrum allocation to AMS(R)S in the above bands and activities in the ITU-R, including WRC and study Groups, to improve this situations.
Noting new ITU-R Report responding to Res.222 concluded that intersystem real-time pre-emption would not be effective to solve AMS(R)S spectrum problem, it is requested to support for agenda of WRC-10 to consider other appropriate measures to ensure future spectrum availability for AMS(R)S in 1.6/1.5 GHz bands to be discussed at WRC-10.
2. Discussions
2.1 Status of Spectrum Allocation for AMS(R)S
Up to WRC-97, the sub-bands 1545-1555 MHz (space-to-Earth) and 1646.5-1656.5 MHz (Earth-to-space) were exclusively allocated to AMS(R)S within the bands 1525-1559 MHz and 1626.5-1660.5 MHz.
At WRC-97, allocation to the MSS in the bands 1525-1559 MHz and 1626.5-1660.5 MHz were made generic and a provision, now numbered 5.357A, was adopted to satisfy the requirements of aeronautical safety-related communications in the sub-bands 1545-1555 MHz and 1646.5-1656.5 MHz.
R.R. 5.357A now indicates as;
" In applying the procedures of Section II of Article 9 to the mobile-satellite service in the bands 1545- 1555 MHz and 1646.5-1656.5 MHz, priority shall be given to accommodating the spectrum requirements of the aeronautical mobile-satellite (R) service providing transmission of messages with priority 1 to 6 in Article 44. Aeronautical mobile-satellite (R) service communications with priority 1 to 6 in Article 44 shall have priority access and immediate availability, by pre-emption if necessary, over all other mobile-satellite communications operating within a network. Mobile-satellite systems shall not cause unacceptable interference to, or claim protection from, aeronautical mobile-satellite (R) service communications with priority 1 to 6 in Article 44. Account shall be taken of the priority of safety-related communications in the other mobile-satellite services. (The provisions of Resolution 222 (WRC-2000) shall apply.) (WRC-2000)"
As the 1.6/1.5 GHz bands were heavily congested, bi-lateral and multi-lateral coordination under this provision did not provide required spectrum for AMS(R)S. Japan proposed to improve this situation by enhancing this provision and Resolution.
Then WRC-2000 discussed this issue again and adopted Resolution 222 of;
"resolves
1 that, in frequency coordination of MSSs in the bands 1525-159 MHz and 1626.5- 1660.5 MHz, administrations shall ensure that the spectrum needed for distress, urgency and safety communications of GMDSS, as elaborated in Articles 32 and 33, in the bands where No. 5.353A applies, and for AMS(R)S communications within priority categories 1 to 6 of Article 44 in the bands where No. 5.357A applies is accommodated;
2 that administrations shall ensure the use of the latest technical advances, which may include prioritization and real-time pre-emptive access between MSS systems, when necessary and where feasible, in order to achieve the most flexible and practical use of the generic allocations;
3 that administrations shall ensure that MSS operators carrying non-safety-related traffic yield capacity, as and when necessary, to accommodate the spectrum requirements for distress, urgency and safety communication of GMDSS communications, as elaborated in Articles 32 and 33, and for AMS(R)S communications within priority categories 1 to 6 of Article 44; this could be achieved in advance through the coordination process in resolved 1, and, when necessary and where feasible, through prioritization and real-time pre-emptive access,"
and
"invites ITU-R
to complete studies to determine the feasibility and practicality of prioritization and real-time pre-emptive access between different networks of mobile-satellite systems as referred to in resolves 2 above, while taking into account the latest technical advances in order to maximize spectral efficiency,"
However, as most of these sub-bands were already occupied by increasing non-safety communications, current spectrum requirements of AMS(R)S are not satisfied. Therefore, it seems to be difficult to expect future long-term and stable spectrum availability for AMS(R)S in these bands under current provisions of the R.R.
As the APT Administrations considered that without long term stable availability for AMS(R)S spectrum, aeronautical safety communication could not be provided in 1.6/1.5 GHz bands, and proposed to WRC-03 to consider this issue and to establish an Agenda item for WRC-07.
However, other administrations and regional telecommunications organization did not support this proposal. Then, WRC-03 merely agreed to consider this issue at WRC-07 under Agenda Item 7.2 by Res. 803 as a provisional Agenda of WRC-10 by;
"2.3 to consider results of ITU-R studies in accordance with Resolution 222 (WRC-2000) to ensure spectrum availability and protection for the aeronautical mobile-satellite (R) service, and to take appropriate action on this subject, while retaining the generic allocation for the mobile-satellite service;"
For the success of establishing new Agenda Item for WRC-10, it is essential to obtain global support by the all regional telecommunications organization, especially by the CEPT in Europe and the CITEL in Americas.
2.2 ITU-R Studies on AMS(R)S - Intersystem Real-time Pre-emption
To respond the request by Res. 222, ITU-R has been studied to determine feasibility and practicability of prioritization and real-time pre-emptive access (intersystem real-time pre-emption) since its 10th meeting in autumn 2000.
Studies were based on contributions from Japan, Canada and United Kingdom participating delegations from these countries and others such as France, UAE and USA.
WP8D considered various elements, such as characteristics of the aeronautical safety communications and aeronautical traffics, applicability of real-time pre-emption and its practicality and effectiveness. The study has also identified a number of significant technical, operational and economic issues that would have to be overcome to make "prioritization and intersystem real-time pre-emption" a reality.
The concept of the real-time pre-emptive access was proposed as an expedient to open the bands of 1545-1555, 1646.5 - 1656.5 MHz, which was formerly allocated exclusively to AMS(R)S, to generic MSS. Such function is referred in current Radio Regulations and Resolutions with expectation of applying it to the cases between different networks since it is already used in the same network.
Although some mobile-satellite networks currently provide intra-system pre-emptive access functions, there are no actual MSS systems providing "prioritization and intersystem real-time pre-emption" functions, and despite several years of study there are no methods yet developed.
It was summarized that "prioritization and intersystem real-time pre-emption" would not necessarily increase the efficiency of spectrum use compared to the current situation, but it would certainly complicate substantially the coordination process and network structure. Furthermore, it may not satisfy the operational and commercial requirements of AMS(R)S communications.
The study has concluded that "prioritization and intersystem real-time pre-emption" is not practical and, without significant advance in technology, is unlikely to be feasible for technical, operational and economical reasons.
The results of the study was adopted by WP 8D in its 17th meeting in September 2005 and approved by SG8 in November 2005 as Report ITU-R M.[PRE-EMPT] (See Annex 1).
It was decided that the summary and the conclusions of this Report will be included in the Chapter 7 of the CPM Report (preliminary Agenda item 2.3 of Resolution 803 for WRC-10).
2.3 Process to ensure long term and stable availability of AMS(R)S spectrum
The 1.6/1.5 GHz shall be essential element of the next generation of the aeronautical mobile satellite system to support safety communications.
Current provisions and procedures for frequency assignments for AMS(R)S is insufficient to satisfy future demand for AMS(R)S in the bands with rapidly increasing spectrum requirement for the mobile satellite communications.
For example, Japan has faced the difficulty to get necessary spectrum for long term operation because Operator review Meeting (ORM) in Regions1/3 is held every year forassignment actual spectrum in only Next Year. Also Japan is not able tojoin the NorthAmerican Operators Meeting.
As results of the WP8D study on prioritization and intersystem real-time pre-emption concluded that it would not ensure spectrum availability and protection for the AMS(R)S communications for the future.
As the situation is getting worse, it is urged to provide appropriate measures to ensure long-term and stable spectrum availability for AMS(R)S at the future WRC with sufficient support by Administrations and regional telecommunications organizations.
WG-F members are encouraged to participate in the preparatory work for the WRC-07 and associated activities in the ITU-R Study Groups and CPM to obtain sufficient support by their respective Administrations and regional telecommunication organization for approving WRC-10 Agenda Item on this matter at WRC-07.
3. Action by the Meeting
WG-F members are invited to consider this paper which is an element of establishing WRC-10 Agenda Item to ensure future spectrum availability for AMS(R)S to be discussed in the WRC-07 Agenda Item 7.2, and to coordinate this issue with their respective Administrations and regional telecommunications organizations.
Annex:
1. ITU-R Report M. [PRE-EMPT] (Document 8/99)
/ INTERNATIONAL TELECOMMUNICATION UNIONRADIOCOMMUNICATION
STUDY GROUPS / Document 8/99-E
31 October 2005
English only
Source:Document 8D/TEMP/166(Rev.1)
Working Party 8D
DRAFT new Report ITU-R M. [PRE-EMPT]
Feasibility and practicality of prioritization and real-time preemptive access between different networks of MSS in
the bands 1 525-1 559 MHz and 1 626.5-1 660.5 MHz
1Introduction and background
At WRC-97 the MSS allocations in the 1 525.0-1 559.0 MHz and 1 626.5-1 660.5 MHz bands were made generic, and Resolution 218 was adopted. At WRC-2000, this Resolution was replaced with Resolution 222.
Resolution 222 (WRC-2000) resolves 2 states:
“that administrations shall ensure the use of the latest technical advances, which may include prioritization and real-time pre-emptive access between MSS systems, when necessary and where feasible, in order to achieve the most flexible and practical use of the generic allocations.”
Resolution 222 (WRC-2000) also invites ITU-R
“to complete studies to determine the feasibility and practicality of prioritization and realtime pre-emptive access between different networks of mobile-satellite systems as referred to in resolves 2 above, while taking into account the latest technical advances in order to maximize spectral efficiency”.
Application of “prioritization and intersystem real-time pre-emption” is one method by which the spectrum requirements of priority AMS(R)S traffic could be ensured. It was intended to improve spectrum efficiency in the case that distress communication occurs with very low probability by shared use of the same spectrum by other communications with low priority.
A work plan responding to the request of Resolution222 (WRC-2000) was established in 2001.Several contributions have been submitted to the meetings of Working Party 8D for the study.The work plan indicates steps for determining feasibility and practicality of prioritization and real-time pre-emptive access between different MSS networks (hereafter indicated as “prioritization and intersystem real-time preemption”) as below.
Completion of revision of Recommendation ITU-R M.1089.
Definition of the terms “immediate availability” and “real-time pre-emptive access”.
Identification of scenarios where real-time pre-emption would be applied.
Investigation of potential methodologies and mechanisms to accommodate prioritization and call pre-emption processes (e.g. spectrum reserve pool).
Determination of feasibility and further development of technical and operational factors relating to the interface architecture between MSS systems operating in the frequency band of interest.
A revision of Recommendation ITU-R M.1089 was adopted in 2002. This Report addresses the remaining items in the work plan.
It is noted that, in resolves 2.3 of Resolution 803, WRC-03 adopted the following preliminary agenda item for WRC10:
2.3to consider results of ITUR studies in accordance with Resolution222 (WRC2000) to ensure spectrum availability and protection for the aeronautical mobile-satellite (R) service, and to take appropriate action on this subject, while retaining the generic allocation for the mobilesatellite service;
2Definitions
2.1Immediate and real-time
Radio Regulations footnotes 5.353A, 5.357A and 5.362A use the term “immediate availability”.Resolution 222 also addresses the term “real-time pre-emptive access”.Some have questioned what “immediate” and “real-time” mean in terms of time (in seconds, minutes, etc.) to accomplish the actions intended.
The term “immediate” means a very short period of time (such as a few seconds) as perceived by an individual.An engineer trying to implement this would look at what is possible from a technology point of view and laws of physics. There is also the operational aspect, where an action is not needed in an instant but depends on the operational environment. Therefore, “immediate” could be a range of values.
From a regulatory point of view it may be difficult to define the term “immediate”, as it would have different values dependent on the operating environment. The term “immediate” can be defined as a period of time “less than X seconds”, where “X” is to be determined and might vary depending on the operating environment.The value “X” should account for various factors such as propagation delays, computer processing time, authentication, etc.
The term “real-time” also means that spectrum is made available to the requesting system within a specified delay.
2.2Prioritization and pre-emptive access
The terms of “prioritization” and “pre-emptive access” or “pre-emption” are used in this report.
In the context of this report, the term “priority” means that if multiple messages are competing for access to a communications resource, then AMS(R)S messages with priority categories (1-6) will be granted access first and followed by other messages.
The term “prioritization” is the treatment of different message types in order of their established priority.
The terms of “intersystempre-emption” or “intersystem pre-emptive access” means accommodating AMS(R)S safety communication messages by transferring spectrum for a limited period of time despite the current usage of the spectrum within a specified delay that is determined via analysis of the operational requirements and characteristics of the MSS networks involved.
2.3Other definitions
Taking into account above and discussions in Section 3.2, following definitions are also used for the purpose of this Report:
“immediate availability”: assignment by the network of required channels for safety communication within a specified period;
“capacity yielding”:action of providing required spectrum for AMS(R)S communications by releasing spectrums for non-safety communications in other MSS networks;
3Identification of scenarios where real-time pre-emptive access would be applied
3.1Characteristics and requirements of AMS(R)S communications
Requirements of AMS(R)S communications and safety communications are well defined by ICAO and ITU documents as follows;
Annex 10 to the Convention on ICAO
Volume III, Part I, Chapter 4:Aeronautical Mobile-Satellite Service
ITU Constitution
Article 40:Priority of Telecommunications Concerning Safety of Life
Radio Regulations
4.10:Protection of safety services
5.357A and Resolution 222:Priority and protection of AMS(R)S communications
ITU-R Recommendations
a)M.1037: “Bit error performance objectives for aeronautical mobile-satellite (R) service (AMS(R)S) radio link”.
b)M.1089: “Technical considerations for the coordination of mobile-satellite systems supporting the aeronautical mobile-satellite (R) service (AMS(R)S)”.
c)M.1180: “Availability of communication circuits in the aeronautical mobile-satellite (R) services (AMS(R)S)”.
d)M.1233: “Technical considerations for sharing satellite network resources between the mobile-satellite service (MSS) (other than the aeronautical mobile-satellite (R) service (AMS(R)S)) and AMS(R)S”.
e)M.1234:“Permissible level of interference in a digital channel of a geostationary-satellite network in the aeronautical mobile-satellite (R) service (AMS(R)S) in the bands 1545 to 1555MHz and 1646.5 to 1656.5 MHz and its associated feeder links caused by other networks of this service and the fixed-satellite service”.
It is noted that some requirements relating to communication delay time, which would significantly affect the applicability of “prioritization and intersystem real-time pre-emption”, have not clearly been defined yet. However, acceptable call set-up delay time for the air traffic control communications is generally considered as about 500 ms.
Other characteristics and requirements of AMS(R)S communications are summarized in Annex 1.
3.2Conditions in which pre-emptive access would be applied
3.2.1Characteristics of aeronautical traffic
For identifying scenarios where “prioritization and intersystem real-time pre-emption” would be required, it may be useful to estimate characteristics of peak instantaneous aircraft count (PIAC) using satellite communications as shown in Annex2.