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S-DOCSIS Satellite Internet

DOCSIS over satellite is basically the DOCSIS cable modem standard adapted for satellite platforms. Data Over Cable System Interface Standard (DOCSIS) is technically not a satellite standard, but a cable modem standard from CableLabs.

2way2sat - S-DOCSIS Surfbeam

To work well over satellite links, the DOCSIS protocol was modified to support, in addition to QAM, modulation schemes, such as QPSK. DOCSIS over Satellite allows satellite broadband operators to leverage technologies already used in cable modem networks, as well as off-the-shelf back office and network management software, which gives it economies of scale. DOCSIS also provides QoS controls that allow deployment of tiered services, value-added services such as VoIP, security features and other configurations for broadband networks.

Intelsat and Telesat are supporters, as is VSAT manufacturer ViaSat. ViaSat''s Surfbeam platform is based on DOCSIS 1.1, while primary additions in DOCSIS 2.0 are CDMA (Code Division Multiple Access) return channel waveforms.

WildBlue uses DOCSIS equipment for its Ka-band broadband service on Telesat''s Anik F2 satellite. Downstream speeds up to 1.5 Mbps are available. However, WildBlue is not the only DOCSIS-based service. Intelsat, Pegaso in Latin America and Eutelsat are among the players who are embracing DOCSIS, at least on a trial basis. ViaSat says it has agreements to provide the Surfbeam DOCSIS platform to more than 10 different satellite service providers. Their focus is on offering broadband access via satellite to consumers, SOHO and SME customers.

Critics say the DOCSIS satellite specification falls short because DOCSIS was designed for cable networks, not satellite. They pretend that DOCSIS does not account for attributes unique to a satellite environment, such as the variable link attenuation due to atmospheric conditions and long round-trip delay. Also, DOCSIS over satellite is comparatively less field-proven than its competitors.

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