P1246990944WJRMv

1
Satellite-Based Internet Joe Montana IT 488
Fall, 2003
2
Source Material

• IEEE published material
• Satellite-based Internet a Tutorial (Yurong Hu
  and Victor O.K. Li), IEEE Comm., March 2001.
• A Survey of Future Broadband Multimedia Satellite
  Systems, Issues and Trends (John Farserotu
  Ramjee Prasad), IEEE Comm., June 2000.
• Broadband Satellite Systems (Daniel Bem et.al)
  IEEE Surveys, 1st Quarter 2000.
• Internet research
• http//www.irwincom.com/idvs-summary.txt (Irwin
  Consulting Report Internet Delivery via
  Satellite, June 1999)
• Dr. Jeremy Allnutt class notes
• Leila Z. Ribeiro Class Handouts
• Students research papers
• Kwabena Konadu Rafael Chaparro
• Kim Wee
• Semirames Miranda

3
Introduction
4
Internet Services

• Defined as any service in which data traffic
  originates from, travels over, or is destined for
  the public Internet -- growing from approximately
  5.4 Gbps by year-end 1999 to an estimated 21 Gbps
  by 2003.

5
Service Options

•  Internet backbone interconnection provisioning.
  (Intelsat, Loral-Orion, PanAmSat, etc). Great
  fraction of revenue source in current systems.
• Last mile (end-user access points) more recent
  approach. Some systems already operating
  (DirectPC and Starband). Many systems proposed
  for future.

6
Backbone Interconnection

• Point-to-point Internet backbone interconnection
  services represent the single largest
  identifiable market for satellite Internet
  services today.  
• As new fiber is continually deployed worldwide,
  the addressable market for point-to-point
  satellite Internet services will gradually
  diminish.
• In the long term, satellite services that
  leverage the inherent strengths of satellite
  communications systems (broadcasting) will be the
  most successful.

7
Last Mile Solutions

• Consists of connecting users to network access
  points directly.
• Satellite networks have clear advantages against
  other terrestrial systems with respect to its
  inherent capability to reach customers anywhere,
  anytime.
• The main challenges for last mile solutions
  rely on providing enough bandwidth in two
  directions (two-way broadband capability) to low
  cost end user equipment.
• Providing Internet service to mobile end users
  constitutes another challenge by itself.

8
Scope of Discussion

• Mobile Applications Broadband Internet access
  over mobile (3G). GSO or NGSO options.
• Currently supported with limitations low data
  rate.
• Future support by Teledesic, Inmarsat
• (Extension of mobile voice systems discussed in
  previous classes)
• Fixed applications (Direct-to-Home) Typically
  GSO systems, some NGSO systems. Examples
• Current systems DirectPC and Starband
• Future Teledesic, Astrolink, Spaceway-GEO and
  Skybridge

9
System Design
10
Orbit Selection

• GSO option Advantage ? Larger Coverage
• Distance challenge
• Large delay (trouble for interactive real-time
  applications)
• Large propagation loss (requires higher
  transmitting powers and antenna gains)
• NGSO option Advantage ? Smaller Delay
• Variable looking angle challenge
• Requires sophisticated tracking techniques or,
  most of the times, omni-directional antennas.
• Requires support to handoff from one satellite
  to another.
• Hybrid option Network including some GSO and
  some NGSO satellites in order to get the best of
  both worlds. Ex. Spaceway

11
Frequency Bands

• Most commonly used
• C Band (4-8 GHz) very congested already.
• Ku Band (10-18 GHz) Majority of DBS systems, as
  well as current Internet DTH systems (DirectPC
  and Starband).
• Ka band (18-31 GHz) Offers higher bandwidth with
  smaller antennas, but suffers more environmental
  impairments and is less massively produced as of
  today (more expensive) when compared to C and Ka.

12
Architectures

• Bent pipes Satellites act as repeaters. Signal
  is amplified and retransmitted but there is no
  improvement in the C/N ratio, since there is no
  demodulation, decoding or other type of
  processing. No possibility of ISL, longer delay
  due to multiple hops.
• On-Board-Processing Satellite performs tasks
  like demodulation and decoding which allow signal
  recovery before retransmission (new coding and
  modulation). Since the signal is available at
  some point in baseband, other activities are also
  possible, such as routing, switching, etc. Allows
  ISL implementation.

13
Architecture with Bent Pipe
Satellite-Based Internet A Tutorial Yurong Hu
and Victor O. K. Li, The University of Hong
Kong IEEE Communications Magazine - March 2001
14
Architecture with OBP and ISL
Satellite-Based Internet A Tutorial Yurong Hu
and Victor O. K. Li, The University of Hong
Kong IEEE Communications Magazine - March 2001
15
Terminals and User Asymetry

• Interactive terminals can both transmit and
  receive data directly to/from satellite. Still
  expensive for DTH users (e.g. Starband terminal
  costs 400 200 installation fee).
• Initial DBS Internet services offered went for
  one-way option, with satellite receive-only user
  units, and upstream sent via terrestrial link.
  Ex. DirectPC first generation.
• Since Internet traffic is becoming progressively
  LESS asymmetrical, one way solutions dont have
  great chances for success in the near future.

16
Multiple Access Control

• To support QoS provisioning for data traffic, a
  requires priorities. Real-time traffic has the
  highest priority.
• Three implementation groups
• Fixed Assignment Pre-assigned channels based on
  FDMA, TDMA or CDMA implementation options.
• Random access Contention based (Aloha and its
  variations). Each station transmits when needed.
  Collisions occur for simultaneous transmissions.
• Demand Assignment (DAMA) Resource negotiation
  phase prior to data transmission. Bandwidth
  allocated on demand using FDMA, TDMA or CDMA
  schemes.

17
Routing Schemes

• GSO Routing over terrestrial network (no ISL).
• LEO Routing
• Dynamic Topology Support to inter-satellite
  handover, inter-beam handover.
• Availability of ISL form a mesh network topology
  in the sky. Intra-plane and Inter-plane ISL may
  be supported.

18
Transport Protocol

• TCP/IP over satellite links present some issues
  that require modifications on the protocol
  implementation
• Typical slow start TCP implementation could be
  replaced by larger initial windows.
• Spoofing to compensate larger Round-trip time
  (RTT) inherent to satellite links (mainly GSOs),
  by sending false ACKs to trick TCP into
  continuing transmission.

19
Case Studies
20
Future Systems
A Survey of Future Broadband Multimedia Satellite
Systems, Issues and Trends John Farserotu, CSEM
Ramjee Prasad, Aalborg University IEEE
Communications Magazine June 2000
21
Future Systems
Satellite-Based Internet A Tutorial Yurong Hu
and Victor O. K. Li, The University of Hong
Kong IEEE Communications Magazine - March 2001
22
Astrolink (2003)

• The Astrolink satellite constellation contains
  nine GEO satellites
• Ka-band satellite system. The uplink is
  28.3528.8 GHz and 29.2530.0 GHz. The downlink
  is 19.720.2 GHz.
• System designed to support high-speed multimedia
  communication.
• Employs OBP for increased efficiency and OBS for
  flexibility. Each satellite is an integral part
  of the communication network, as opposed to being
  a bent-pipe relay.
• Data rates range from as low as 16 kb/s to 9.6
  Mb/s. 384 kb/s are supported to 90 cm dishes,
  which makes Astrolink potentially suitable for
  large mobile platforms.

23
Cybestar (2001)

• Ka-band constellation consisting of three GEO
  satellites.
• Originally planned to deploy a Ku/Ka-band fleet
  of three Ka-band satellites with as many as 48
  LEO Ku-band satellites. While the company is
  still planning to build a Ka-band system, its
  primary focus is on successfully implementing its
  Ku-band service offering, which uses Loral
  Skynet's Telstar 5 to deliver broadband services
  to businesses.
• Cyberstar-Ka is designed to provide IP
  multicasting services to Internet service
  providers (ISPs), large and small business
  organizations, and multimedia content providers.
• The capacity of the Cyberstar-Ka network is 9.6
  Gb/s. IP multicasting is implemented based on
  frame relay and ATM technology.

24
Spaceway

• May get confusing as there are many phases and
  configurations to what is called Spaceway.
• The Spaceway final configuration plans for 16 GEO
  and 20 medium earth orbit (MEO) satellites.
• Hughes Electronics Corp. has committed 1.4
  billion to Hughes Spaceway for the launch three
  GEO Ka-band satellites for service starting in
  2001, which will be the platform for the next
  generation DirecPC.
• Under the Hughes H-Link proposal filed with the
  FCC, 22 MEOs (2 spares) will be launched using
  Ku-band to offer broadband services.
• The HughesNET proposal consists of 70 Ku-band
  LEOs for packet-switched and circuit-switched
  Internet access.

25
Spaceway (2002)

• The Spaceway final configuration plans for 16 GEO
  and 20 medium earth orbit (MEO) satellites.
• Ka-band system designed to support high-speed
  data, Internet access, and broadband multimedia
  information services.
• The Spaceway satellite architecture is based on
  conventional bent-pipe relay.
• It offers high QoS (bit error rate, BER to users with terminals as small as 0.66 m, at
  data rates starting at 16 kb/s up to 6 Mb/s.
• The Spaceway system is compatible with ATM,
  integrated services digital network (ISDN), frame
  relay, and X.25 terrestrial standards.

26
SkyBridge (2002)

• Skybridge, the only one of the major players that
  has a LEO-based Ku-band solution, has expanded
  from a proposed constellation of 64 LEO Ku-band
  satellites to 80 satellites for a total of 4.2
  billion. Besides the decision to use Ku-band,
  Skybridge is excluding any complex
  switching-in-the-sky and inter-satellite link
  capabilities.
• Constellation consists of 80 satellites in
  circular LEO at 1469 km. The orbital inclination
  is 53s.
• The system is intended to support advanced
  information services (e.g., interactive
  multimedia) at data rates from 16 kb/s to as high
  as 60 Mb/s.
• SkyBridge satellite design is based on a
  bent-pipe relay architecture.

27
SkyBridge (cont.)

• Unlike the other systems described so far,
  SkyBridge is a Ku-band system. The uplink
  operates at 12.7514.5 GHz, and the downlink is
  10.712.75 GHz. The choice of Ku-band is due to
  the availability of Ku-band technology.
• SkyBridge gateway stations interface with
  terrestrial networks via ATM switches. The
  majority of services are expected to be IP-based.
  SkyBridge employs a combined code-/time-/frequency
  -division multiple access (CDMA/TDMA/ FDMA)
  waveform however, the satellites themselves are
  transparent (i.e., bent-pipe).
• Spot beams, with frequency reuse in each beam,
  are employed to enhance capacity. SkyBridge is
  designed to accommodate traffic from over 20
  million simultaneous users.

28
Teledesic (2004)

• The Teledesic constellation consists of 288
  satellites in 12 planes of 24 satellites.
• Teledesic is a Ka-band system. The uplink
  operates at 28.629.1 GHz, and the downlink at
  18.819.3 GHz. It uses signals at 60 GHz for ISLs
  between adjacent satellites in each orbital
  plane.
• Teledesic employs full OBP and OBS (on-board
  switching). The system is designed to be an
  "Internet in the sky."
• It offers high-quality voice, data, and
  multimedia information services. QoS performance
  is designed for a BER
• Multiple access is a combination of
  multifrequency TDMA (MF-TDMA) on the uplink and
  asynchronous TDMA (ATDMA) on the downlink.

29
Teledesic (cont.)

• The capacity of the network is planned to be 10
  Gb/s. User connections of 2 Mb/s on the uplink
  and 64 Mb/s on the downlink are possible.
• A minimum elevation angle of 40.25 enables the
  Teledesic system to achieve an availability of
  99.9 percent.
• Teledesic's 288 LEO Ka-band satellites bring
  enormous complexity to the table in terms of
  untried technology, on-board switching and
  inter-satellite capabilities. While this
  complexity may translate into more service
  flexibility over time, we expect to see further
  adjustments to Teledesics business plan as the
  system continues to be developed.

30
iSky (2001)

• iSky, formerly KaStar, is focused on providing
  broadband data and Internet services to North
  America (regional solution).
• This Ka-band system is designed to support
  high-speed two-way Internet access, direct
  broadcast services (DBS), and future personal
  communications systems (PCS) to homes and offices
  via small aperture (e.g., 26 in) antennas.
• The initial constellation consists of two GEO
  satellites. The uplink frequency is 19.220.0
  GHz, and the downlink 29.030.0 GHz.
• Data rates up to 40 Mb/s are envisioned, with
  typical rates in the range of 1.55 Mb/s.

31
Other Last Mile Satellite Systems

• Other planned broadband systems include
• Ka-band payloads on Koreasat 3, which will carry
  three Ka-band transponders
• Astra-1H, the first of two SES Ku/Ka-band
  satellites, originally planned for 1999.
• Tokyo-based Space Communications Corp.'s
  Superbird 2B replacing Ka-band satellite
  Superbird B (originally planned 2000)
• Telespazio is offering a broad menu of multicast
  and broadcast solutions including high speed IP
  connectivity.

32
Regulatory Issues

• The worldwide regulatory trend is towards
  deregulation of telecommunications, and most
  World Trade Organization (WTO) countries are
  adopting non-exclusive licensing arrangements for
  telecommunications service providers in response
  to the WTO Basic Telecommunications Agreement.
• The European Union (EU) also has made substantial
  progress in opening its markets to satellite
  communications and reducing trade barriers, with
  the eventual goal of creating a single market for
  satellite services.

33
Regulatory Issues (cont.)

• Access to most Asian markets requires not only
  landing rights, but also some form of political
  clout because the Internet and broadcasting
  regulations are politically charged issues.
  Bilateral and regional agreements are promoting a
  gradual though uneven opening of markets in Latin
  America.
• Regulatory issues in areas like Africa and the
  Middle East tend to be more related to
  infrastructure development and the high costs of
  Internet services, as well as government
  attitudes towards open access to the Internet.

34
Market Analysis

•  DBS system operators can take advantage of the
  growing demand for Internet content by using
  surplus bandwidth to deliver direct-to-user
  Internet services.
• Current services, which have experienced slow
  consumer uptake, are combining Internet content
  delivered via satellite with a terrestrial return
  path, in conjunction with traditional television
  content.
• The biggest challenge facing the Ka-band industry
  is not technology development, but rather
  business and service development, as well as
  financing.
• Because the networking market changes rapidly
  over time, the need for these ventures to remain
  flexible in terms of types of services and
  applications that can be provided is key.
• By the end of 2001, we expect to see
  approximately 1000 direct-to-user Ka-band sites
  providing 2-way Internet services, with this
  figure growing to over 100,000 by the end of 2003.

35
Market Analysis

• Other options available to end user for Internet
  broadband access include
• DSL
• Cable Modem
• MMDS and LMDS (wireless)
• Terrestrial 3G systems in the case of mobile
  applications.

36
Options for Home Internet Access

• DSL is a modem technology that transforms
  ordinary phone lines into high-speed digital
  lines for internet access. It transmits data in
  both directions simultaneously, at over 1.5 Mbps
  over copper wires up to 18,000 feet (about one
  third of a mile). The main limitation of DSL is
  that the user must be within 18,000 feet of a
  telephone companys exchange office.
• Cable modem is a device that allows high-speed
  internet access via a cable TV network. To
  communicate with a user, the network allocates
  one television channel ( 50-750 MHz range) for
  downstream traffic and another channel (5-42 MHz
  band) for upstream signals. The limitation of the
  cable service is that as the number of users on
  the same cable modem termination system (CMTS)
  increases the communication speed will slow down
  considerably.
• MMDS wireless broadband network has a fixed
  wireless headend that connects to a central
  antenna which broadcasts data to users. The two
  main limitations of wireless MMDS are the
  line-of-sight transmission and broadcast range.

From (adapted) Research Paper TCOM 507
(Student Katherine Wee)
37
Summary

• Future satellite systems will offer an array of
  advanced information services.
• The trend is toward high-speed Internet access
  and broadband multimedia and IP-based services
  over IP and/or IP/ATM networks. Services may
  range from email and voice to broadband
  multicasting and interactive video.
• Satellite architectures may employ OBP, OBS,
  and/or OBR to augment capacity, or traditional
  bent-pipe transponders for simplicity and
  flexibility.
• Constellations may be LEO, MEO, GEO, or
  combinations thereof, dependent on the coverage
  required and the services to be supported.

38
Summary (cont.)

• The use of Ka-band and even higher frequencies
  will be increasingly common as available spectrum
  becomes more scarce.
• Higher frequencies also enable the use of smaller
  terminals and, potentially, greater mobility.
• Integration of emerging and future satellite
  systems with terrestrial networks can help bridge
  the last mile and expand the reach of
  Internet-based services to business and homes.