TC Jacobson & Associates LLC

Internet Development, Streaming Media, DVB Satellite

Sat08

DigitalWorld Satellite 2008 Workshop Info

WHERE: Satellite 2008 Conference
  Washington DC Convention Center
  Room 140A
WHEN: Wednesday, February 27, 2008 starting at 9 A.M.
  (Room booked for 9-11 A.M., but if nobody kicks us out, we could order a pizza and work through lunch and on into the dark night….)

 

Registration

You need to be registered for the Satellite 2008 conference in some way—as a free (exhibits only) attendee, as a regular attendee, or as an exhibitor.

You can register on-line at the conference web site: Satellite 2008 and enter the VIP code BOF. You can also download the pdf registration form.

Send us an email if you plan to join us [thomas (at) tcjnet.com].

Brief

Title:
Low-cost satellite internet infrastructure to support
education in remote and developing regions.

Organizers:
Roland Burger, EU Digitalworld [roland.burger (at) digitalworld.org]
Thomas Jacobson, TCJ & A [thomas (at) tcjnet.com]

Satellites are often the only practical means of implementing connectivity for low-cost student laptops and distant classrooms in remote and developing regions. One goal of this workshop will be to gather and document design requirements and their justifications, to examine how current products might be used to meet them, and to identify areas where further research and development is needed. Discussion will include such topics as: 1) availability and cost of electrical power, 2) harsh operating environments, 3) the need for self installation and maintenance, 4) choosing interactive or multicast, 5) the tolerance of lower-link budget margins and lower availability, 6) integration with local wireless infrastructure, and 7) the use of metadata to support privacy, classification, filtering, rights, and bandwidth management. Individuals bringing slides will be encouraged to briefly present, prior to technical debate.

Preliminary Agenda

Time Item Who
9:00 Welcome & agenda setting Roland and Tom
9:10-10:00 Updates by OLPC, IETF, and industry. Invited speakers
10:00 Step through topics chosen during agenda setting  
12:00 Volunteers meet for lunch to writeup notes  
     
     
     

Topics

This workshop is intended to be informal; everyone is welcome. You are free to suggest additional topics, to come and go from the meeting as you please, and to encourage colleagues who have something to contribute to bring in a few slides on a USB key or CD. We have invited interesting speakers from such places as OLPC, IETF, and industry. If you have an interest in development and satellites, please join us. Immediately after the workshop we will enlist some volunteers to write a summary of key points.

We would appreciate it if individuals would be ready to defend their arguments with supporting facts and references, not so much for participants, but as a way of documenting defensible design requirements. Presentations by vendors of a particular product should try to  provide engineering details rather than product sheet specifications, and claims by users about needs should ideally show how such needs were determined.

If you are making slides for this workshop, please email a preliminary set to thomas (at) tcjnet.com if you can. Speakers should try to limit their talks to around 15 min, unless you check with thomas (at) tcjnet.com or roland.burger (at) digitalworld.org first.

We intend to step through the list of topics below very quickly during the agenda setting process and identify those where there is existing consensus that we can document and skip over, and then choose a few of these topics for in depth discussion.

1) Electrical Power

A typical DVB-S2 RCS terminal appears to consume between 50W to 150W of power, depending on uplink amplifier, duty-cycle, access method, etc. Grid power is not always available in developing regions, and/or may be susceptible to lengthy interruptions. Gasoline or diesel generators require transport of precious fuel, and may not operate 24/7. OLPC for example has made a point of low power designs using alternative energy such as human, solar, or perhaps wind. Is power an issue, and what are the considerations for satellite terminal design?

  • What is the actual (not specified) power consumption for the current generation of two-way satellite terminals (DVB-RCS, DVB-SatMode, S-DOCSIS, IpoS, iDirect, etc.?
  • What portion of schools in developing countries have reliable 24/7 electrical power?
  • Where grid power is available, will battery UPS power suffice, or is a long term outage backup strategy such as a standby generator needed?
  • If it is the case that grid  power can not be relied upon, can low power two-way satellite terminals be designed, and what should the power consumption goals be for such terminals?
  • What is a reasonable cost per watt to use in system design, and what are the alternatives (solar panels w/batteries, wind generators w/batteries, human power, etc.)
  • Should fully interactive two-way architectures be sacrificed for lower power less interactive two-way or one-way only designs that save on electrical power and space segment use?
  • What are the research issues regarding low-cost, low-power terminal devices?

2) Environment

  • What are the dust, humidity, temperature, shock, and wind issues?
  • What are the MTBF/MTTR requirements?
  • Physical security/theft?
  • How can we assure low-cost terminals are also as much as possible environmental friendly and not using hazardous materials?

3) Legal issues

What are the legal impediments for low-cost terminals in the various regions?

  • Use of scrambling and encryption technology such as DVB CAS, DES/AES?
  • Transmitter licensing.
  • Receive antenna placement and safety regulations
  • Import taxes
  • IPR/Patent laws
  • Labor and social security laws

4) Installation and support

Some VSAT operators in remote and developing regions have related that travel and installation cost can exceed equipment cost. Some satellite owners require any terminal that has transmit to be installed by trained/certified “professionals” (perhaps because antenna miss-pointing can potentially cause interference liabilities with adjacent satellites). Efforts have always been made to disable transmit when an antenna is out of signal lock (miss-pointed), or to limit transmit power to acceptable levels.  For developing countries it is very important that terminals be rugged in order to withstand the various demanding environmental conditions.  It is also important to have terminals easily maintained, possibly by local tradespeople.

  • What can be done to facilitate/make possible installation of two-way satellite terminals by end users or local trades people?
  • How can terminals be made more modular and easily maintained by end users.

5) Interactive or multicast

Recent innovations in DVB-S2, ACM, and Ka spot-beams notwithstanding, satellite space segment is expensive, will stay that way for the foreseeable future, and is not always available in the region/footprint needed. The greatest strength of satellites is point-to-multipoint.

  • Should IP multicast, multicast file transfer mechanisms, and forward error correction (FEC) be leveraged to provide a basic Content Delivery Network service as an integral part of satellite services for remote and developing areas?
  • Does such software need to be open source, and are there IPR issues with various FEC algorithms and reliable multicast file transfer protocol designs?
  • Should IP multicast CDN be used only as an overlay on top of satellite or terrestrial two-way infrastructure to free up two-way bandwidth for interactive services, or should receive-only sites with no return channel be supported as well?

6) Availability

Satellite systems are usually conservatively engineered to operate in all types of weather and on the assumption of certain levels of interference from adjacent satellites and other sources. The cost difference between 95% and 99% “availability” can be large in terms of satellite radio power. Modern satellite link protocols such as DVB-S2 allow dynamic adjustment of signal coding.

  • In these applications is it justified to lower availability in order to increase throughput/lower cost per bit, especially if one is using file level FEC on top with appropriate time between turns of the carousel?
  • Can one use new DVB-S2 adjustable/adaptive coding techniques to manage system throughput seasonally, or even diurnally (i.e. in Asia the rain comes after lunch)?

7) Wireless

Low cost laptops use WiFi to connect to school servers, and point-to-point WiFi links using directional hi-gain antennas can be used to link adjacent schools together.

  • Should the satellite receiver be integrated with the school server or exist as a separate autonomous device?
  • What are the integration issues with WiFi/WiMax/MeshWiFi, PLC, etc.
  • Should the satellite FEC scheme support these (i.e. real time streaming video w/FEC repeated over WiFi)?
  • Should the receiver have a content buffer/disk?

8) Content management

Unlike todays optical/WDM based terrestrial internet infrastructure, satellite based internet services do not have infinite bandwidth. Spam and adult material consume a huge amount of internet bandwidth today, not to mention the social/parental issues. Clearly bandwidth must be managed in some way. Because satellite signals are easily received anywhere in the footprint, is some form of signal security necessary?

  • How much and what type of content must be supported?
  • What are the privacy issues?
  • How should/shouldn’t the system architecture navigate the minefield of censorship, DRM, and social mores?
  • What kind of traffic shaping and enforcement is needed just to keep the system working?
  • How should the system integrate with the larger internet—walled garden, meta-data based filters (podcast XML like), DansGuardian type content filters?
  • How can diverse delivery networks, with diverse delivery properties, be integrated into one reliable distribution network?
  • Should the system address character set and language issues,  such as providing extended character set support, or multiple language tracks?

9) Standards

Many will argue that DVB-S2, with its various modes of operation such as CCM and ACM, ability to efficiently saturate transponders and avoid wasteful power back off, and its ability to leverage low cost receiver components developed for the DTH industry makes it the ideal choice for out route (hub to terminal). The jury is still out on in route (terminal to hub), where there are a plethora of competing methods such as RCS, SatMode, etc. as well as more proprietary architectures such as S-DOCSIS, IPoS, IDirect, etc.

  • Is it advantageous to use DVB standard technology to benefit from second sourcing, competition between equipment suppliers, and to allow incremental growth and coexistence of these systems on full transponder DVB carriers used for other applications such as DTH TV?
  • What are the requirements for the in route access method in terms of bandwidth, availability, and type of service (streaming & VOIP, or simply NACKs)?

10) Satellites

The reality is that advanced satellites, similar to IPStar or Wildblue,  with high power spot beams and large numbers of Ka or Ku transponders will not cover many parts of the developing world for years.

  • Does the necessary satellite capacity exist now, or in the near future to meet the need, and in the right foot print?
  • How important is it to minimize the size of the terminal antenna?  Are large C band antennas a choice? For Ku are flat plate antennas advantageous and should system trade offs be made to support them?

I will try to update this as time goes on,

Thomas Jacobson
thomas (at) tcjnet.com

You can see my ideas on all this by looking at: Tom’s XOSAT MIT OLPC Talk