August 2015 Satstream Media announce the launch of SatstreamNet’s
support for High Throughput Satellites (HTS).
High Throughput Satellites (HTS)
have been much talked about in the industry press over recent years because their
deployment is revolutionising the satellite industry. For more detailed information
about HTS, there are some very good video tutorials available on satellite operator
websites. Although there is a range of different HTS architectures being developed,
a common feature of them all is that they have a large number of spot beams across
the satellite footprint that covers the Earth’s surface. These spot beams are small
in diameter and they enable the satellite to have a much higher data throughput in
comparison to a wide-beam satellite due to the ability to re-use radio frequencies
again and again in spots that are spatially separated from each other.
Multicast IP transmissions are most efficient when operating over wide beam satellites
because a single transmission can deliver content to all receivers within the wide
beam, whereas with an HTS, multiple transmissions are required to cover the same
geographical area due to the smaller spot beam sizes. To improve the efficiency
of the multicast IP transmission, it becomes necessary to know where the receivers
are ie which spot beams they are under, in order to avoid transmitting into spot
beams that have no receivers. Within a mobile satellite market such as maritime,
knowledge of the location of the vessels becomes even more important because during
a vessel’s journey from one port to another it may transit several spot beams.
One may ask, given this additional complexity, is it not better to provide content
to mobile satellite markets using a standard unicast delivery method instead of
deploying multicast. Well, consider the following simple example:
If say, 50 vessels have subscribed to a Video on Demand service on a specific HTS
satellite and this service uses unicast IP delivery rather than Multicast IP delivery
and say that 10 of these vessels would like to download the same video material
over the following days and say also that 6 of these vessels are each on a separate
spot beam and the remaining 4 vessels happen to be within the same spot beam then,
with a unicast method of delivery, each vessel downloads the video material independently
of each other, with each data transfer being approximately equivalent. That is out
of the 10 vessels downloading the same video material over the unicast delivery
platform, there would be 10 individual downloads required.
Now consider the impact of providing the same content to the same vessels using
a Multicast IP delivery service. With knowledge of the vessel location, the 6 vessels
located within different spot beams would each require an independent download and
the four vessels under the same spot beam would only require 1 download because
all four vessels under the same spot beam will receive the same Multicast IP stream.
That is out of the 10 vessels downloading the same video material over the Multicast
IP delivery platform, there would only be 7 individual downloads required in this
scenario. Note here that with knowledge of the vessel locations, it would not be
necessary to transmit Multicast IP streams in those spot beams that have no active
subscribers.
There are many scenarios like the one above where a Multicast IP solution and knowledge
of the location of each vessel, will introduce significant efficiencies to a content
delivery service operating over an HTS satellite. For more information about SatstreamNet,
please contact us.