DIMENSIONING OF AERONAUTICAL SATELLITE SERVICES.pdf

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					                                                                                          IAC-02-M.3.07



        DIMENSIONING OF AERONAUTICAL SATELLITE SERVICES


                  A. Jahn, M. Holzbock                                    Markus Werner
           DLR Oberpfaffenhofen, Germany                           TriaGnoSys GmbH, Germany
     Institute of Communications and Navigation          Argelsrieder Feld 22, Wessling-Oberpfaffenhofen
        {Axel.Jahn,Matthias.Holzbock}@dlr.de                     Markus.Werner@triagnosys.com


             .
ABSTRACT —This paper addresses the traffic                as the passenger is used to from its daily life. So
dimensioning        for   aeronautical     services.      mobile telephony and Internet access with
Specifically, it focuses on wireless services such        laptops, either wired or wireless is mandatory
as UMTS and W-LAN in aircraft cabins that                 rather than fixed cabin installations (e.g., flat
connect the passenger via satellite to terrestrial        screens in backseats which are more
infrastructure. A multi-service model is presented        appropriate for in-flight entertainment). The EC
with specific bit rate and traffic characteristics for    project WirelessCabin (IST-2001-37466) is
manifold services. Furthermore it is discussed            looking into those radio access technologies to
how different satellite systems can serve the             be transported via satellite to terrestrial
traffic demand arising from the long-haul traffic         backbones [2]. The project will provide UMTS
over oceans and land masses. Finally, a                   services, W-LAN IEEE 802.11b and Bluetooth to
numerical example shows the expected traffic for          the cabin passengers. With the advent of new
a geostationary satellite system.                         services a detailed investigation of the expected
                                                          traffic is necessary in order to plan the needed
1. INTRODUCTION                                           capacities to fulfil the QoS demands. This paper
                                                          will thus describe a methodology for the planning
The demand for making air travelling more                 of such systems.
pleasant, secure and productive for passengers
is one of the winning factors for airlines and            The remainder of the paper is organised as
aircraft industry. Current trends are towards high        follows: section 2 gives a short description of the
data rate communication services, in particular           WirelessCabin system architecture. In section 3
Internet applications. In an aeronautical scenario        the services to be offered for the passengers are
global coverage is essential for providing                characterised by their traffic statistics and a
continuous       service.     Therefore    satellite      multi-service model for multimedia traffic is
communication becomes indispensable, and                  described. In section 4 the capacity planning of
together with the ever increasing data rate               the expected traffic is explained, taking into
requirements of applications, aeronautical                account several potential satellite constellations.
satellite communication meets an expansive                Finally a numerical example is given.
market. According to analysts, the addressable
market amounts to $70 billion through the next
ten years [1].                                            2. WIRELESS CABIN SYSTEM
                                                             ARCHITECTURE
It is anticipated that any early-to-market entry will
take an evolutionary approach extending existing          The service scenario considers travellers in
systems and services, or leasing currently                aircraft on the move. In the future, airliners will
available (mainly GEO) transponder capacity. A            provide a variety of entertainment and
key issue for the success of such systems is the          communications equipment to the passenger.
passenger acceptance. It is believed that the             Since people are becoming more and more used
ease of access to the service can be                      to their own communications equipment, such as
predominantly achieved by wireless techniques             mobile phones and laptops with Internet
                                                          connection, either through a network interface
.
                                                          card or dial-in access through modems,
 Copyright  2002 by DLR. Published by the                business travellers will soon be demanding
American Institute of Aeronautics and                     wireless access to communication services. So
Astronautics, Inc., with permission. Released to          far, GSM telephony is prohibited in commercial
IAF/IAA/AIAA to publish in all forms.
                                                                                                                                                                           IAC-02-M.3.07


aircraft due to the uncertain certification situation                                                  For instance, access to VPN or the possibility of
and the expected high interference levels of the                                                       being reachable under the user’s telephone
TDMA technology. With the advent of spread                                                             number while flying, will become real with the
spectrum systems such as UMTS and W-LAN,                                                               network architecture.
and low power pico-cell access such as                                                                 The WirelessCabin architecture and its
Bluetooth, this situation is likely to change,                                                        components are conceptually depicted in Figure
especially if new aircraft avionics technologies                                                       1. Such an infrastructure comprises:
are considered, or if the communications                                                                   -   Several wireless access segments in the
technologies are inline with aircraft development                                                              aircraft cabin, namely a wireless LAN
as today for the new Airbus long-haul A380                                                                     according to IEEE 802.11b standard for
aircraft. With small business jets such as                                                                     IP services, an UMTS pico-cell for
Bombadier LearJets, Gulfstream etc., individual                                                                personal and data communications, and
equipment certification is already established.                                                                Bluetooth 1.1, as well as a standard
When wireless access technologies in aircraft                                                                  wired IP LAN.
cabins are envisaged for passenger service, the                                                            -   A satellite segment for interconnection of
most important standards for future use are                                                                    the cabin with the terrestrial telecom
considered to be:       UMTS with UTRAN air                                                                    networks. The different cabin services
interface, Bluetooth, and W-LAN IEEE                                                                          must be integrated and interconnected
802.11b. Of course, these access technologies                                                                  using a service integrator, that allows
will co-exist with each other, beside conventional                                                             the separation and transportation of the
IP fixed wired networks. The wireless access                                                                   services over a single or several satellite
solution is compatible with other kinds of IFE,                                                                bearers. Peculiarities, such as limited
such as live TV on board or provision of Internet                                                              bandwidth, asymmetric data rates on
access with dedicated installed hardware in the                                                                satellite up- and down-link, and dynamic
cabin seats. Hence, it should not be seen as an                                                                traffic demand between the different
alternative to wired architecture in an aircraft, but                                                          services and handover between satellite
as a complementary service for the passengers.                                                                 bearers need to be addressed. In order


                                                                                              Space Segment

                                                                              Satellite
                                                                                                                                                        Ground Segment
                                                                                                                       Satellite dish


   Cabin Segment                                                                                                                       e
                                                                                                                                     Modm Bank




                                                                                                                             Multiplexer



                                                Sat-Modem                                                 Terrestrial telecom router                                           Passenger’s
                       Satellite dish
                                                                                                                                                                               Company
                                                                                                                                                                               Intranet
                                                                         Aircraft Protocol Functions
                                    Modm Bank
                                      e

                                                                         IP mobility Server
                                                                         AAA
                                                                         VPN
                               Multiplexer                               DHCP                                                                     AAA, Billing
    W-LAN        Service Integrator                                      QoS                      Service Integrator                              Mobility ISP server
                                                                                                                            LAN IF                VPN, mobility support,
                                                                    LAN                                 Multiplexer
                                                                                                                                                  QoS support
                                                                                             UMTS IF              Bluetooth IF
                                                                                                                                                                                    IP
                 Laptop computer                 Laptop computer
    UMTS             Laptop computer
                                                                                                                                                                                 Backbone
                                                      Laptop computer                                       Bluetooth
                                                            Laptop computer                                 UMTS IF
                                                                   Laptop computer
                                                                                                                       UMTS Core
                                                                                                 RNC
                                                                                                                      SGSN                       GGSN


                                                                                                                      MSC                        GMSC
     Bluetooth                                                                                                                                                                    PSTN
                                                                                                                                                                                  UMTS
                                                                                                                                                                                  GSM
                                                                                               Aircom Provider Segment
                                                              Figure 1: WirelessCabin network architecture
                                                                                                                IAC-02-M.3.07


        to minimize the cost (satellite resources)
        for a given QoS efficient interworking
                                                                              Satellite Connection
        between the service integrator and the
        satellite segment will be required.                                   Connection to telecom networks is considered to
    -   An aircom service provider segment                                    be achieved by satellites with large coverage
        supporting the integrated cabin services.                             areas [3], especially over oceanic regions during
        The aircom provider segment provides                                  long-haul flights. The service concept needs to
        the interconnection to the terrestrial                                take into account today’s peculiarities of satellite
        personal and data networks as well as                                 communications, thus it must cope with the
        the Internet backbone. For the UMTS                                   available or in near future available satellite
        cabin service, a subset of the UMTS                                   technology, and interworking must be performed
        core network must be available.                                       at aircraft interface level with the satellite
The provision of such a heterogeneous access                                  segment, cf. Figure 2:
network with collectively mobile users requires
the development of new protocol concepts to                                       •    Only restricted satellite data rates will be
support                                                                                available in the near future; thus the
    • the integrated services with dynamic                                             bandwidth that is requested by standard
        bandwidth sharing among the services                                           interfaces of the wireless standards
                                                                                       needs to be adapted to the available
        and asymmetrical data rate;
                                                                                       bandwidth (typically: 432 kb/s in down-
    • IP mobility and virtual private networks
                                                                                       link, 144 kb/s up-link (Inmarsat B-
        (VPN) for the individual passengers in
        the mobile network;                                                            GAN), or 5 Mb/s in down-link, 1.5 Mb/s
    • authentication,           admission      and                                     in up-link (Connexion by Boeing)).
        accounting (AAA) in the mobile network,                                        Furthermore,       dynamic       bandwidth
        especially taking into account the                                             management is needed to allocate
        necessity to support different pricing                                         higher bit rates from temporarily unused
        concepts for each passenger in the                                             services to other service.
        mobile network and the interaction of                                     •    Currently, few geostationary satellites
        airline, satellite provider, aircom service                                    such as the Inmarsat fleet are available
        provider      and      terrestrial  service                                    for two-way communications, that cover
        providers.                                                                     the land masses and the oceans. Ku-
                                                                                       band may be used on a secondary

                                              Forward link          Sat G/W


                                                        Satellite




                                                                                      telco WAN
                                  Service                                                                      Service
                                 Integrator                                                                   Integrator


      Laptop computer
                                                        Satellite
                                                                    Sat G/W                                Service provider
          Laptop computer
                                                     Return link
               Laptop computer




                                 Cabin Segment



                                              Figure 2: Satellite connection scenario
                                                                                                IAC-02-M.3.07


         allocation basis for aeronautical mobile          be bundled and transported between a pair of
         satellite services (AMSS) but bandwidth           Service     Integrators.   It   performs     the
         is scarce and coverage is mostly                  encapsulation of the services and the adaptation
         provided over continents. K/Ka-band               of the protocols.
         satellites will be launched in the near
                                                           The SI multiplexer is envisaged to assign
         future, again here continental coverage
                                                           variable capacities to the streams, controlled by
         is mainly intended. The scenario must
                                                           a bandwidth manager that monitors also the
         thus consider
                                                           QoS requirements of the different service
               o the use of different satellite
                                                           connections. Changes in capacity assignment
                   systems, which will probably
                                                           must be signalled to the SI at the other
                   force the support of different
                                                           communication end. The heterogeneous traffic
                   service bearers, and
                                                           stream      is    then     sent    to     streaming
               o handover between satellite
                                                           splitter/combiner. This unit is envisaged to
                   systems.
                                                           support several satellite segments and to
         It is assumed that each satellite segment
                                                           perform handover between them. Asymmetrical
         is connected via terrestrial wide area
                                                           data rates in inbound and outbound directions
         networks or via the IP backbone to the
                                                           can be managed here. Adaptation to the
         aircom service provider.
                                                           supported satellite segments are done by
    •    Asymmetrical data rates in satellite up-          medium access controllers (MAC) in a modular
         and down-links, that may also be caused           manner. Towards the terminal side, the
         to operate in conjunction with different          interfaces of the wireless access standards need
         satellites systems for up- and down-link.         to interwork with the transport streaming of the
         The service portfolio in the cabin and the        SI by specific adaptation layers (AL). These ALs
         service integration needs to cope with            have to be designed according to the analysis of
         this possibility.                                 the impact of delay, jitter and restricted / variable
                                                           bandwidth on the protocol stack. Buffering (to
                                                           compensate delay jumps at handover) and jitter
The different wireless access services of UMTS,            compensation for real-time services (e.g., voice)
W-LAN and Bluetooth require an integration of              must be also provided here. Above scheme was
the services over the satellite. The central part of       submitted for patenting in [4].
the service portfolio provisioning is the service
integrator (SI), cf. Figure 3. The service
integrator will provide the interfaces for the
wireless and wired service access points in the
cabin, as well as the interface to the terrestrial
networks at aircom provider site. All services will
                                        Nav. / Pos.
    Cabin                               Data                                            Satellite
    Interfaces                                                                          Interfaces

                                        Navigation
                 protocol                Interface
    IP I/O                                                                    Sat MAC   I/O 1        e.g., L-Band
                   AL                   (Arinc 429)                                                  Up-link


                 protocol                                                                            e.g., Ku-Band
    IP I/O                                                  HO                Sat MAC   I/O 2        Down-link
                   AL                                     Manager
                             QoS
                                          Service
                            Service
                            Monitor        MUX                                                       To / from
                 protocol                                 Streamig
   UMTS I/O                                                                              …           Satellite modems
                   AL                                   Splitter/comb.
                                                                         IP

   Bluetooth     protocol                                                                            e.g., DVB-S (RCS)
                                         Bandwidth                            Sat MAC   I/O n        Down-link
      I/O          AL                     Manager
                                       + QoS Support
    MPEG
     A/V                                                            MPEG A/V




                                          Figure 3: Service Integrator
                                                                                                     IAC-02-M.3.07


3. CABIN SERVICES AND MULTI-SERVICE                                  TABLE I. CATEGORIZED AIRCOM SERVICES
   TRAFFIC MODEL
                                                                Category        Services
A central issue affecting the addressable                       Infotainment    www, email, live TV, gambling,
market(s) is in how far the underlying business                                 phone, intelligent travel
case combines separate market segments which                                    information
are potentially closely related to the aeronautical             Office          email, www, phone, fax, video-
broadband satellite communications (AirCom)                                     conferencing, file transfer
segment in a narrow, i.e. “communication-only”,                 Telemedicine video conferencing, vital data
sense. Concerning AirCom-specific services we                                   trans-mission
propose a classification into five categories with              Flight security cabin & cockpit survey, flight
their particular service profiles as summarized in                              recorder data transmission
Table I. A more detailed discussion of AirCom                   Logistics &     video and audio server upload,
services and the rationale for this classification              maintenance aircraft maintenance data
can be found in [5], as well as an overview of the
state-of-the-art in terms of existing and planned             traffic generated and received on-board the
systems and services.                                         aircraft, an earlier developed linear scalable
                                                              multi-service traffic model is currently being
The next step is now to derive the individual                 adapted to the aeronautical scenario. Figure 4
traffic statistics for the identified service                 provides an overview and details of the original
categories. Table II contains a list of traffic               traffic model as it has been used for the
parameters for possible aircom communication                  dimensioning of the EuroSkyWay satellite
services. Note that the usage parameters are                  system and its particular terminal types [6].
estimated currently and will be refined by
passenger interviews in the WirelessCabin                     The traffic generated and received by a single
project. The second column shows how                          aircraft is a function of
frequently an application may be used. The                         • the distribution of passengers among
numbers apply for business travellers. It is                            first, business and economy class,
assumed that the video conferencing services                            (obviously passengers in first and
will only apply to dedicated corporate aircraft.                        business class are more keen on using
The third column shows the average duration of                          AirCom services)
the usage of an application. The fourth and fifth                  • the duration of the flight, (it seems
columns show the bit rates required by the                              reasonable that passengers of short
applications. Here, forward link means the                              flights will use virtually no AirCom
direction towards the aircraft. The last column                         services, it is thinkable to introduce a
indicates the burstiness which is defined here as                       threshold in the AirCom traffic analysis
peak bit rate divided by the average bit rate. If                       for the flight duration, flights taking less
more than one value is given for the burstiness,                        than 1.5 hours could be neglected)
they refer to the different service components of                  • the physiological flight time (it is more
a multimedia service.                                                   likely that passengers flying from East to
                                                                        West on long haul flights will make use
In particular, for modelling the multi-service                          of AirCom than passengers flying from

                                   TABLE II. AIRCOM TRAFFIC CHARACTERISTICS

   Service, Application       Application   Mean holding Data rate return link   Data rate forward      Burstiness
                              frequency         time                                    link
   Telephony                      2/h          3 min           9.6 kb/s              9.6 kb/s             2.857
   Video telephony            0.01/flight      5 min         16+64 kb/s             16+64 kb/s             1.0
   Video conference           0.01/flight     15 min        16+384 kb/s            16+384 kb/s              3
   Shared Applications        0.01/flight     15 min          384 kb/s               384 kb/s              2.5
   Video surveillance         permanent      unlimited         64 kb/s                    -                1.0
   Document mail service          5/h         0.25 s           16 kb/s                16 kb/s              1.0
   (email, short messaging,
   paging)
   File transfer                 5/h            4s              144 kb/s             144 kb/s              20
   WWW                           2/h           30 min           16 kb/s              144 kb/s              20
                                                                                                                                                                                                        IAC-02-M.3.07



       D

       1
            Service/A ppl.
                          SatT type

            T elephony, telefax
                                      port.
                                       A
                                       1
                                              m obile
                                                 A
                                                 1
                                                        port.
                                                         B
                                                         1
                                                                m obile
                                                                   B
                                                                   1
                                                                          port.
                                                                           C
                                                                           1
                                                                                  m obile
                                                                                     C
                                                                                     1
                                                                                            port.
                                                                                             D
                                                                                             1
                                                                                                                              Terminal types            P o rtab le
                                                                                                                                                                                   S atT -A             S a tT -B              S a tT -C              S a tT -D


       2    V ideo telephony           0         0       0         0       1         1       0                                                          C a se                     L ap -top            B riefcase             B riefcase             P alm -to p
       3    V ideo conference          0         0       0         0       1         1       0                                                          U se                       In d iv idu al       In div id u al         Ind ivid u al          In d iv id ual
       4    V ideo surveillance        0         0       1         1       1         1       0                                                          M o b ility d u rin g      No                   No                     No                     P ers on al
       5    T V broadcasting           0         0       0         0       0         1       0                                                          op era tio n
                      Te
                                                                                                                                                        U p lin k in fo rm .       16 -1 2 8 K b it/s   1 6 -5 12 K b it/s     1 6 -20 4 8 K b it/s   4 -64 K b it/s
       6    A udio broadcasting        0         1       0         1       0         1       0
                                                                                                                                                        ra te (g ran u la rity )   (16 K B it/s)        (1 6 K B it/s)         (1 6 K B it/s)         (4 K B it/s)
       7    D ocum ent broad-          1         0       1         1       1         1       0
                                                                                                          # users per terminal type                     D o w n lin k m a x .      2.0 48 M bit/s       2 .0 4 8 M b it/s      2 .0 4 8 M b it/s      6 4 K b it/s

                                                                                                                       n
            casting
                        rm p r
                                                                                                                                                        in fo rm . ra te



                                                                                                                   tio
       8    D igital (vehicle) in-        0     1        0          1      0        1         0
            form ation broadcast.                                                                                and region)                            M ob ile
                                                                                                                                                        M o b ile ty p e           C ar                 P lan e, S hip ,       P lan e, S h ip,




                                                                                                               dic
                          in ofil

        9   V ideography                  0     0        1          0      1        1         0                                                                                                         B u s, T rain,         B u s, T rain ,
       10   D atabase access for          1     0        1          1      1        1         0                                                                                                         T ruck                 T ru ck



                                                                                                             re l
            retrieval services                                                                                                                          U se                       In d iv idu al       In div id u al /       G ro u p
                            al es

                                                                                                                                                                                                        G ro u p
       11   C om puter                    1     0        1          1      1        1         0


                                                                                                           p
                                                                                                                                                        M o b ility d u rin g      Y es                 Y es                   Y es
            interconnection



                                                                                                         et o de
                               se

                                                                                                                                                        op era tio n
       12   D ocum ent m ail              1     0        1          1      1        1         1
                                                                                                                                                        U p lin k in fo rm .       16 -1 6 0 K b it/s   1 6 -5 12 K b it/s     1 6 -20 4 8 K b it/s
            service (em ail,paging,                                                                                                                     ra te (g ran u la rity )   (16 K B it/s)        (1 6 K B it/s)         (1 6 K B it/s)


                                                                                                       rk m
            short m essaging)
                                 rv

                                                                                                                                                        D o w n lin k m a x .      2.0 48 M bit/s       2 .0 4 8 M b it/s      2 .0 4 8 M b it/s
       13   File transfer                 1     0        1          1      1        1         0



                                                                                                    Ma
                                                                                                                                                        in fo rm . ra te
                                    ic
                                                                 e

                                                                                                                                                                                                                           1
      A(i ) =                   ∑∑    s         u
                                                         δ s ,u ⋅ N u (i ) ⋅ mBH , s ,u ⋅ mMS, s ,u ⋅ mSA , s ,u ⋅ mGT , s ,u ⋅ λ* ⋅
                                                                                                                                 s
                                                                                                                                                                                                                         µs
                                                                                                                                                                                                                                  ⋅ Rs ⋅ bs
                                                                                                                    s         service type s ,
     A(i) = cumulative busy hour                                                                                r
     source traffic in region i
                                                                                                          facto               user terminal u
                                                                                                                                                              ete
                                                                                                                                                                 rs
                                                                                   ce                                                                       am
                                                                                rvi                                                                     p ar
                                                                                                                                            fic
                    SatT typeport. mobile port. mobile port. mobile port.

                                                                            i e
                                                                                                                    ID           Service/  Application              Mean            Data rates          Burstiness

                                                                          ltB s C C                                                      raf λ
     Service/Appl.                        A         A           B                                          D                    Application frequency             holding   return link    forward link
                                                                                                                                       T
                                                                Mu
                                                                                                                                                                    time   (from user)       (to user)
     Telephony, telefax                   1         1           1           1           0.6         0.6     1                                       ∗
                                                                                                                                                                     1/µ        Rr              Rf          b
     Video telephony                      0         0           0           0           0.3         0.3     0           1   Telephony, Telefax     1/h              3 min   4; 64 kbps      4; 64 kbps    0.35
                                                                                                                        2   Video telephony       2/day            5 min 64+1150 kbps 64+1150 kbps         1.0
     Video conference                     0         0           0           0           0.1         0.1     0           3   Video conference      1/day            60 min 64+1920 kbps 64+1920 kbps .33/.35
     Video surveillance                   0         0           1           1           1           1       0           4   Video surveillance   1/month          1 month    32 kbps      64+1920 kbps 0.33/1.0
                                                                                                                        5   TV broadcasting         .                 .          .               .          .
     TV broadcasting                      0         0           0           0           0           0.5     0
                                                                                                                        6   Audio broadcasting      .                 .          .               .          .
     Audio                                0         1           0           1           0           0.5     0           7   Document broad-         .                 .          .               .          .
                                                                                                                               i
     broadcasting


       Figure 4: Components of the linear scalable multi-service traffic model for capacity dimensioning of
                                         broadband satellite systems.
        West to East, who should sleep to                                                                                    path leads from existing L-band systems such as
        minimize the jetlag effects),                                                                                        Inmarsat GAN (see Figure 5) or B-GAN in few
    • the set of available services.                                                                                         years up to C/Ku band and existing GEO
The traffic should be described as superposition                                                                             transponders, whereas the “revolutionary” path
of the traffic generated by each passenger                                                                                   may target from the beginning at advanced K/Ka
according to the characteristics of the desired                                                                              band technology and the design of a tailor-made,
services in terms of                                                                                                         potentially non-GEO system.
    • data rate: symmetric, asymmetric, peak
        rate, sustainable rate,                                                                                              The system dimensioning process can be
    • QoS parameters: delay, delay variation,                                                                                structured in several steps:
        loss rate.                                                                                                             •    Determination of gross traffic per aircraft
                                                                                                                                    using the multi-service model as

4. SERVICE DIMENSIONING

This section provides an overview of key issues
and steps for the systematic system
dimensioning of WirelessCabin aircom satellite
communications system. We will tackle the
satellite constellations as potential candidates for
aircom services as well as the gross traffic
calculation and assignment process.

Different market entry options and reference
business cases must be taken into account in an
initial stage of a system design. The evolutionary


                                                                                                                                        Figure 5: Inmarsat L-band coverage
                                                                                         IAC-02-M.3.07


       described in section 3.
 •     Determination of the timely and locally
       varying traffic, depending on the flight path
       and flight schedule, assuming also a
       service roll-out scenario for different
       airlines and aircraft types.
  •    Identification of potential serving satellites
       and their coverage areas.
  •    Mapping and traffic allocation of the
       aircom traffic to the satellite systems.
Two      key     observations      concerning     the
“geographic market” are (i) the pronounced
asymmetry of market opportunities between                           Figure 7: ABATE traffic density
northern and southern hemisphere (partly just a
result of our earth’s “continental layout”), and (ii)       •   departure and destination airport
the fact that a significant share of the                        locations,
addressable market is at higher (northern)                  •   related departure and arrival times
latitudes, especially with the important long-haul              (either from exact time tables, or as a
intercontinental flight routes between the                      flight frequency model),
European, North American and East Asian                     •   a simple model for cruising speed (e.g.,
regions. Both observations are illustrated in                   simply a constant speed derived from
Figure 6, although its view is Europe-centric; the              the flight distance divided by the flight
underlying flight route investigations have been                duration, neglecting any influences from
performed within the European ACTS project                      other flight phases),
ABATE and have been used for design and                     •   a simple model for geographic flight
dimensioning studies of an aeronautical                         routes (e.g., each flight following a great
subsystem of the EuroSkyWay satellite                           circle between start and destination).
communications system [6].
                                                        Actual flight routes are very variable due to the
Flight route statistics/data are relevant to get        needed adaptation to the jet streams. Variations
(series of) snapshots of airplane distribution in       of plus minus 1000 km with respect to the
the service coverage area, which are essential          expected position on the geometric shortest
input information for satellite antenna spot beam       route are normal. This could then mean
design     and     overall      system     capacity     variations in latitude/longitude of up to ±9° with
dimensioning. Usually, the latter will be based on      respect to the expected position on the shortest
some worst case situation extracted from the            route.
snapshots. A simplified minimum set of data
describing a global or regional flight scenario can     The results of the traffic calculation with
be based on                                             overlaying spotbeam coverage from the ABATE
                                                        system are depicted in Figure 7. In the figure the
                                                        density is shown for the time 17:00 h.

                                                        The capacity planning is here important. The
                                                        goal is to minimize the peak capacity per
                                                        spotbeam in order to reduce the requirements
                                                        for the satellite payload. Several algorithms have
                                                        been proposed in [7]. After distributing the traffic
                                                        to the spotbeams using the HomFlow graph
                                                        algorithm, a carrier assignment has been
                                                        performed using impairment graphs and graph
                                                        colouring. The result of this process can be seen
                                                        in Figure 8. One can easily see that adjacent
                                                        spotbeams must be decoupled by separate
     Figure 6: ABATE coverage and flight route          frequencies. In general, three frequencies would
                   density [6].                         suffice. However, spotbeam #47 and #53 are
                                                        coupled through large overlapping. Thus, at least
                                                                                       IAC-02-M.3.07




               Figure 8: Optimized aircom traffic and carrier assignment for the ABATE scenario

four frequencies are required. The highest traffic      6. REFERENCES
density in Europe is caused by medium haul air
flights in the evening busy hour while                   [1] Connexion by BoeingSM, Press Release, 27
transatlantic flights require fewer capacity.                April 2000.
                                                         [2] http://www.wirelesscabin.com
                                                         [3] E. Lutz, M. Werner, A. Jahn: "Satellite
5. ACKNOWLEDGEMENT                                           Systems for Personal and Broadband
                                                             Communications", Springer-Verlag, Berlin,
The background of this work is in part the IST               2000.
project       IST-2001-37466      WirelessCabin          [4] M. Holzbock, A. Jahn: "Verfahren zum
(Development and Demonstrator of Wireless                    Anbinden      von     zur      Kommunikation
Access for Multimedia Services in Aircraft                   dienenden,     einem      kollektiv mobilen
Cabins), sponsored by the European Union. The                Benutzernetzwerk angehörenden Benutzer-
project team consists of German Aerospace                    Endgräten." Patent filing No.: 102 08 689.3
Center (DLR, project co-ordinator), Airbus (D),              dated 28.02.2002, German Patent Office
Ericsson Telecommunicazioni (I), ESYS (GB),              [5] M. Werner, M. Holzbock, “System Design for
Inmarsat (GB), KID Systeme (D), Siemens                      Aeronautical       Broadband        Satellite
Austria (A), TriaGnoSys (D), University of                   Communications,” in Proceedings Int.
Bradford (GB). The effort of the project partners            Conference on Communications (ICC’02),
is gratefully acknowledged. This paper, however,             paper # J03-3, 2002.
does not implicitly represent the opinion of the         [6] M. Marinelli, R. Perez-Leal, M. Luglio, L.
project partners. The authors are solely                     Zhang, A. Franchi, A. Jahn, “SECOMS and
responsible for it and do not represent the                  ABATE system architectures and relevant
opinion of the European Community. The                       space segment,” in Proceedings 3rd ACTS
European Community is not responsible for the                Mobile Communications Summit, pp. 659-
use of any data in the paper.                                665, 1998.
                                                         [7] A. Jahn, “Resource Management Model and
                                                             Performance      Evaluation     for Satellite
                                                             Communications”, Int. J. on Satellite
                                                             Communications, vol. 19, 2001, pp. 169-202.

				
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