sYM.rP/1 SYMPOSIUM ON FUTURE GLOBAL COMMUNICATIONS, NAVtcATtON - - PDF document
sYM.rP/1 SYMPOSIUM ON FUTURE GLOBAL COMMUNICATIONS, NAVtcATtON AND SURVETLLANCE (CNS) SYSTEMS MONTREAL, 4.5 SEPTEMBER 1991 COMPILATION OF PRESENTATIONS Compilad by the ICAO Secretariat and published by authority of the
SYMPOSIUM ON FUTURE GLOBAL COMMUNICATIONS, NAVtcATtON AND SURVETLLANCE (CNS) SYSTEMS
MONTREAL, 4.5 SEPTEMBER 1991 COMPILATION OF PRESENTATIONS
sYM.rP/1
INTERNATIONAL CIVIL AVIATION ORGANIZATION MONTREAL . CANADA
Compilad by the ICAO Secretariat and published by authority
Secrelary General. The views conta¡ned in this document ar€ those
€xperts and th6ir publication does nol ¡mply an €ndorsement by ICAO.
sYM
P/l s E s s r o N 2 . 3
SESSION 2.3 AERONAUTICAL I.ÍOBILE SATELLITE SERVICE (AüSS)
( P r e s e n t e d b y D . D i e z ) l. FANS conclus ion 1.1 From its study of new concepts and new technologies, the FANS Corunittee concluded that che exploitation
technology is the only now víable solution that will enable one to overcone the shortcomings
present conmunications, navigation, and surveillance (CNS) systern and to fulfil the needs and requirenents
future
(page 3, executive summary, FANS/4 Report, Doe 9524). 2. Present communications shortcomings 2.1 The rnajor shortcomings
corununications system are: a) che line-of-sight propagation limitacion
frequency (VHF) and/or the accuracy and reliability lirnitations imposed by the variability
c h a r a c t e r i s t i c s
b) the difficulty, caused by a variety
to implenent presenc communications systens and operate Chen in a consistent rnanner in large parcs of the world; and c) the limitations
cornmunications and the lack
digital air-ground data interchange systens to support modern automated systems in the air and on the ground. 3 . A M S S m a i o r b e n e f i t s 3.1 The aeronautical rnobile satellite service (MSS) will
those Iirnitations and wiIl provide: a) global communications coverage from very low to very high altitudes, ernbracing remote,
and oceanic areas, \^títh the exception
regions (see Figure 2 and F i g u r e 3 ) ; a n d b) digital data interchange bet'reen the air-ground systens to fu1ly exploit the automated eapabilities
application, the automatic dependent surveillance (ADS), in which aircraft automatical-ly transnit, via the data 1ínk, positional data derived fron
systerns, will also provide global surveillance coverage in the areas s p e c í f i e d u n d e r a ) ( s e e F i g u r e 4 ) .
sYM- IPll s E s s r o N 2 . 3 2 . 3 - 2
3.2 The A.l'fS S will provide four service types, tlro safety and t!¡o non-safety services. Air traffic control (ATC) and aeronautical
control (AOC) are the safety services, and aeronautical adninistrative communication (AAC) and aeronautical passenger communication (APC) are the
r ¡ u r ' - s d r e L J ¡ u , r e > .
4. Al.rSSP 4.1 The progress toward uslng satellite communications for aeronautical safety is being realized through the preparation
and Reconmended Practices (SARPs) and guídance material by the ICAO Aeronautical Mobile- SatelIite Service (AMSS) Panel. 4.2 The A¡,tS S Panel has adopted che systen defined in the INMARSAT Systen Definition Manual (SDM) and the Aeronautical Radio, Inc. (ARINC) Characteristic 741 . Both, the SDM and the ARINC 741 r¿i1l be continuously amended as SARPS develap. 4.3 The A.!ÍSS Panel was also lasked to prepare a sunnary doclrment on t h e s y s t e r ¡ a r c h i t e c t u r e , d e s i g n c h a r a c t e r i s t i c s , b e n e f i t s a n d a p p l i c a c i o n s
AMSS, to be recommended for prornulgation by 1CA0 in the form of an advisory
^ 1 w i l l b e a v a i L a b l e . 5. A.I"ISS mai
5.L The rnajor elements of the AMSS are the space segment (satellites), ground earth stations (GESS) , and aircraft earth stations (AESs) (see F i g u r e 5 ) . 5 . 2 S p a c e s e s m e n t 5.2.1 AMSS satellites
above the Equator in a Seostationary
More than one-third
surface is visíble from this altitude, and three satellites approximarely equally spaced in Iongitude can provide global coverage. No line-of-sight radio coverage is available from geostationary satellites at the polar regions where, at latitudes greater than approxinately 80 degrees, the path to the satellite approaches the horizon (see Figure 3). 5.2.2 INMARSAT
firsr sarellire ro neer ICAO A.f,tS S Srandards r¡as launched successfully
ac 64.5 degrees east over the Indian Ocean. 5 . 2 , 3 A n u ¡ n b e r o f o r g a n i z a t i o n s a r e p l a n n i n g t o l a u n c h s a r e l - t i t e s i n inclined ( non- geos tacionary ) orbits that \ri1l also provide coverage of polar regions. The first
in the late 1990s, providing coverage of the Norch Polar region, It is not anticipated that
2 . 3 - 3 continuous satellite coverage of lhe exEreme SouEh Polar region will be available in che. tineframe covered by FANS. 5.3 Ground garth station (GES) 5.3.1 The GEs consLsts of a dlsh antenna and eleccronics dedlcated to conmunLcations operaEions through the satelllte to and from the atrcraft' It provides the interface between ¿he satellite and fixed terrestrial voice and data netlrorks such as conmon ICAO Data Incerchange Network (CIDIN), the publlc s\ritched telephone neEwork, priva¡e networks, and dedicated lines that might be used for Eine-crltical applicaEions. A GES may or may not be located at ¿n ATS facility, depending on óperatlonal requlreÍIents and arrangenents made betveen the satellite servic; provÍder and the civil aviation authority (see Figure 5).
sYM- rPll sE ssro N 2 .3
l ink sizes
s . 3 . 2
The GES antenna typically is 9 co 13 rnetres in diameter and
at C-band (4/6 CHz frorn/uo the satellice). Alternative feeder fiequencies, for example at Ku-band (ú/La GHz), perrnic smaller antenna and freedorn from potential terrestrial interference, but at the expense preater effect
actenuation. 5 . 4 A i r c r a f t e a r t h s t a t i o n ( A E S ) 5.4.1 The AES is comprised of an on-board transnitter /teceivet unit that includes nodulators, demodulaEors, signal processors and voice codecs; internal concrollers:
frequency Power arnplifiers, and the antenna sub-system (see Flgure 5 and Figure 6). 6. AMSS channels and band 6.1 The radio links between satellice and aircraft are imPle¡nented using three types
for packet daEa which have been given the letter designations P, R and T; and a fourth, designated C-channel , which designaces a circuic-¡rode channel for voice and data (see Figure 7). 6-2 The P-channel is a time division nultiplexed continuous P¿cket data channel from GES Eo AES which carries signalling and user data. Aircraft must continuously monitor this channel after log-on to a GES. 6.3 The R-channel is a rnultipl-e access channel , used in the AES to GES direction, h'hich carríes signalling and user dala. It uses the "slotted aloha" protocof to permic randorn access by multiple aircraft. A GES continuously monitors its R-channels. 6.4 The T-channel is a reservation time division nultiPle access (TDMA) channel used frorn AES to GES only. A GES receiving a request from an AES through the R-channel for T-channel capacity reserves time slots for AES
sYM- 1Pl1 s E s s I o N 2 . 3
2 . 3 - 4 transmissions according to message length. The sending AES then transmics nessages in the reserved time slots according to priority. 6.5 The C-channel is a continuous, fu1l-duplex frequency division multÍple access ( FDMA) channel used for voice and data and is allocated
dernand through an R-channel from the AES, or assigned directly by the CES.
6 . 6 5 . 6 . 1 6 . 1 . 2
Rates The P, R and T channels work at rates ranging from 600 bits/s
10 500 bits/s, using A-BPSK modulation for channel rares of 2 400 bíts/s less, and A-QPSK modulation for channel rates higher rhan 2 400 bics/s. C-channels work at rates fron 6 000 bits/s to 21 000 bits/s.
ó a n o
to and 6 . 7 , I C o r u n u n i c a t i o n s b e t w e e n a i r c r a f t a n d s a t e l l i t e
to 1.6 GHz frequency band, allocated for this purpose because of its suitable radio characceristics. I 545 - 1 555 MHz fror0 satellite to AES | 6 4 6 . 5 - 1 6 5 6 . 5 M H z f r o m A E S r o s a r e l l i t e Channel spacing is such as to provide sufficient separation to reduce adjacent channel incerference and ensure channel tuning in the presence
due to the relative velocity between the aircrafr and the s a t e l l i t e . 6,7,3 Transrnitter and receiver tuning increments are normally 2.5 k{z, therefore, the number of channels available in 10 MHz is approxir¡acely 400: Channels can be efficíently reused when sDot beams are irnplemented.
6 . 1 . 4 The estimate for AMSS for rhe year 20lO is for 14.5 ro 17.5 ¡,fHz
the exclusive allotment in each direction, which is considerably more than the 10 MHz now allotted in each dírection. States should provide rnaximum support to ICAO at the next International Te lecomr¡uni c at ion Union (ITU) World Administrative Radio Conference (Malaga-1992) (ftARC-92) when requesting rhe r e q u i r e d b a n d . 1 . Al'f S S aoplications 7,l Autonatic dependent surveillance and direct pilot-controller data link communications using packet transmission are l-ikely to be the first ATS applications
especially in oceanic and remote areas. 7.2 In high-density continental areas, the integration
data could enhance the SSR surveillance function by providing coverage at 10¡,, altitudes and blind areas and improving the ground. tracking
SYM- IPlI
sE ssro N 2 .3
2 . 3 - 5
increase the level
redundancy, and allow the integrity
navigation system to be monitored. AI,f S S will also permit che direct digítal data interchange between air and ground expert systens whieh will increase ATS capacity ald improve airspace utíIization. ATC experC systems v¡hích will perforrn rnuch of che current control-Ier,s rouEine l¡ork, will be the only !¿ay to efficiently cope with the increase
traffic forecast for the near future (forecasts for Central Europe show that by the year 20OO aircraft movements w i l l b e 1 0 0 p e r c e n t g r e a t e r t h a n i n 1 9 8 7 ) . 1.3 AMSS vill also provide global AOC, AAC and APC corrununications coverage (voice and data) .
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