|
|
|
|
|
|
|
|
Advanced Technologies,
Protocols & Standards
|
|
Broadband Satellite
Networks
Delivering High Throughput and ROI
|
|
|
Dr. Ron
Smith
TRW Technical Specialist, Digital Communications
Satellite Communications Directorate
TRW
Evaluating Satellite Network Architectures
- Comparing Bent Pipe, circuit switched and fast packet architectures in terms of economic
use of frequency
- Determining the most suitable network architecture for multimedia applications
- How do the economics change between satellite architectures when the traffic is varied
- Examining the advantages of fast packet architectures in order to cope with bursty
traffic
- What is the impact on user costs to access the satellite
- What types of return can the satellite operator expect in a multimedia environment. The
technology is ready
|
Protocol Issues
|
|
|
Dr. W. Timothy
Strayer
Senior Scientist, Department of Internetwork Research
BBN Technologies
The popular perception is that TCP/IP does not run well over
satellite networks, even though TCP/IP was designed with satellite networks in mind in the
1970s. Communication over satellites introduces a long delay (for GEOS, delay can be as
much as 250 ms each way). This delay means there can be a lot of data in flight -- the
so-called "delay-bandwidth product". But original TCP has known problems with a
link with very large delay -- the window size is too small, the sequence space wraps too
fast, and the acknowledgment scheme is too pedantic. Modifications to TCP to improve its
overall performance while being fair to other connections, namely slow-start and
congestion avoidance, do not work well as the delay or bandwidth or both increase. This
talk will present the general problems with TCP and the fixes that have been applied, and
consider how these fixes may help or hinder TCP/IP's performance over today's satellite
networks. We will also discuss current and expected near future efforts to improve
performance.
|
DVB Technology
Applied to the Delivery of IP Services
|
|
|
Burt Liebowitz
President & Chief Operating Officer
NetSat Express, Inc.
Digital
Video Broadcasting (DVB) is the European standard for transmitting digitalized video
streams. The standard had been modified to incorporate delivery of data streams. Because
it is standards based, DVB technology provides an opportunity to lower the cost and
improve the quality of satellite-based IP transmission systems. This talk provides a basic
description of DVB technology and how it can be used in the transmission of bundled
IP services. By using technology based on the DVB standard we can:
- control which stations are entitled to receive program streams
- lower space segment costs through statistical multiplexing
- reduce antenna sizes by using saturated transponders.
We can also expect to see specialized application
software developed around the standard, supporting such features as QoS control, and
scheduling.
The speaker will present an example of an integrated service
satellite uplink, and will discuss the tradeoffs involved in selecting and implementing a
DVB system for IP the transmission. |
|
| Return to Agenda |
|
|
|
