Challenges of Creating Global Internets - The Teledesic Example

Hans-Werner Braun

Table of Contents

• Slides from this Talk
• Stan Barber's Notes
• June 1997 NANOG Home Page

Stan Barber's Notes

HWB just started working there a year ago.

Teledesic is using satellites.

There are three types of satellite systems: geostationary, medium and low earth orbit.

Of the low earth orbit systems, there are little (for paging), big (telephony), and broadband (high speed)

Teledesic is using broadband low-earth orbit (LEO) mechanisms. It takes a lot of satellites to do global LEO.

Some tradeoffs

• One-way versus bidirectional communications
• Access from 2.4 KB to gigabit speed
• System responsiveness and latency
• Number of satellites (10s to a thousand)
• The original Teledesic design was for 840 satellites.
• Moving versus stationary (relative to the ground station) satellites
• Tracking becomes an issue

Boeing has proposed a new design using 288 satellites.

Teledesic tradeoffs

• Elevation masks
• Steered antenna -- hope to use some kind of phase array antenna
• Line of sight
• Rain/terrain blocking
• Cell size in coverage area
• Frequency spectrum
• Frequency band (Ka Band) (18-20Ghz)
• Lowest frequencies bandwidth with the capacity for global broadband networking
• Intersatellite links (each satellite will communicate with 8 others)
• Handoffs
• No up-down-up-down needs
• Tracking of earth fixed cells
• System Cost -- $9Billion

Each intersatellite communication will run at 1Gb (if possible)

• Each satellite will span 40 degrees, which should include many many cells.

On the ground, there will be two types of terminals. One will be a standard access terminal (or Ground stations) which will support 2Mbs and gigabit satellites.

Network implementation

• Fast packet switch (not necessarily ATM)
• Fixed length packet header
• Fixed length packet payload
• Self contained packet headers
• Network (destination) addresses based on geographic location
• Cell/termianl hierarchy

Teledesic will move all kinds of information (including data, video and voice).

The infrastructure will support a datagram interface and a "bit-pipe" interface.

Resource requirements

• Access terminal ->satellite
  • Satellite intersatellite system
    • Downlink

Traffic on the Internet is very transaction-oriented (mostly because of web traffic).

Teledesic wants to work with ISPs to provide remote access and reduce the Internet complexity diameter. There is also the possibility of doing local/wireless signal distribution (mobile computing)

Issues

• Global routing and addressing
  • Multiple BGP sessions need to be avoided.
• Privacy/security/regulation
  • This is pretty obvious.
• Global network management
• Autonomous operations of complex systems
• Aggregation of transactions vs. local term flows
• Global inter-domain service class models
  • Classic QoS/CoS problems
• Service metrics/service auditability
• Understanding of systemic needs and approaches

There are others, like multicasting.

Should there be one at Teledesic?

Implications of Teledesic system to the existing satellite community

• Global standard and gigalink services on demand
• Low cost components and subsystems
• Low cost launches
• Technology and software for automated constellation operations

Teledesic (started in 1988) and got authorization to provide the network in 1997 from FCC.

In 1998, full-scale development will start and in 2000 the equipment will be built with first launch in 2001. First revenue from the system is expected to be generated in 2002.

Questions & Answers

Note:Presentor's comments look like this.

Bill Norton asks: How do you get it fixed? We expect that each satellite will last about 10 years. With that many satellites, it is probably cheaper to built more and replace them than repair them.

Bill Nortonasks: What about systemic failure? The service really can't work unless the whole system is working.

What about mobile users? The primary service model is for fixed location receivers. There are some thoughts about mobility, but there is not a solution right now.

Sue Hares asks: What about the rates? There are two different terminals. One is 2Mb and the other is OC-24. There can’t be very many of the OC-24. The propagation delay should be less than covering the same distance fiber.

Sue Hares asks: What about multicasting? We don’t have an answer yet. I am in the middle on it.

Jim Williams asks: will this be franchised around the world? Probably. Teledesic is working with a number of other providers.