• United States
by John Kenyon, special to Network World

IPoS expands reach of satellite apps

May 03, 20043 mins

IP over Satellite (IPoS), which the Telecommunications Industry Association ratified as TIA-1008 in November 2003, is the only industry standard optimized for delivering IP broadband services over two-way satellite channels.

Until recently, satellite services were based on proprietary systems – a competitive advantage for providers, but one that made it difficult to create and optimize applications and value-added services for the satellite industry. Developers had to create customized applications for each satellite provider.

Satellites are used by thousands of corporations, including those that have several dispersed locations or lack of access to traditional wired broadband services. In response, the industry had to find a way to improve applications development and drive innovation to make network services such as VoIP, VPNs or streaming video available on the majority of satellite networks.

IP over Satellite (IPoS), which the Telecommunications Industry Association ratified as TIA-1008 in November 2003, is the only industry standard optimized for delivering IP broadband services over two-way satellite channels. Already implemented in more than 300,000 deployed satellite terminals (which represents about 70% of the installed market), IPoS will provide a catalyst for dramatic growth in the satellite industry by delivering always-on IP services – such as e-mail, streaming video, Web browsing and IP telephony.

IPoS specifies techniques for transporting IP packets between a central hub terminal (the terminal residing at a service provider network operations center that interfaces with the satellite and the Internet or WAN) and remote terminals (the terminal residing with the end user), using standard geosynchronous satellites. Geosynchronous satellites circle Earth once per day, matching Earth’s rotation on its axis, so that a remote terminal on Earth can point at the satellite at one spot in the sky and not have to track its motion.

When an end user with a remote terminal sends a request for a Web page, IPoS is employed in the inroute – from the remote terminal to the satellite. An IPoS-compatible radio takes the IP packet request, converts it to radio frequency and transmits the data to the satellite.

Between the end user and the satellite, IPoS establishes a Satellite Independent Service Access Point (SI-SAP), a well-defined interface between satellite-dependent functions and application layers, enabling an open service delivery platform. The ability to interface with the SI-SAP makes IPoS easily scalable.

For application developers, and users of the applications, IPoS’ transport architecture is hidden under the SI-SAP and IPv4. This lets companies implement applications that are not affected by improvements and changes in the underlying transport. Applications and value-added services running over IPoS operate at the IP level, simplifying upgrades and portability.

When a request reaches a satellite, IPoS maximizes capacity on the transponder (a circuit on the satellite that receives, modulates, amplifies and re-transmits an uplinked signal) by operating on the same transmission principle as the Ethernet. If two users send requests at the same time, they back up and resend, freeing up capacity, maximizing bandwidth and creating a more cost-effective solution. Then the satellite transmits the amplified but unmodified signal down to the IPoS hub.

In the outroute direction – from the hub, through the satellite, to the satellite remote terminal – IPoS follows the DVB-S standard wherein all traffic to all remote terminals is time-mulitiplexed onto one broadband carrier.

Widespread adoption of IPoS by application developers and manufacturers will let a broader market of competing satellite services give companies a greater choice of broadband solutions.

Ultimately, IPoS will open the doors to a much larger world of satellite services.

Kenyon is senior vice president of Hughes Network Systems. He can be reached at