High Throughput Satellites (HTS) 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. So, to improve the efficiency of Multicast IP transmissions, it becomes necessary to know where the receivers are ie which spot beams they are under, in order to avoid transmitting Multicast IP 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? Our blog describes a simple scenario that shows that even with low numbers of vessel subscribers, a Multicast IP solution is still much more efficient at delivering rich content than a standard unicast method of delivery.

A typical VSAT platform of course, will know the location of all the receivers under each beam and with IP routing and the IGMP protocol, the hub can route IP Multicast traffic to the correct beam seamlessly. If a vessel however, is equipped with a receive-only terminal, the hub cannot know the location of the receiver and as such, another means is required to determine the location. So, if there is a comms link on a vessel using an alternative technology to VSAT, then SatstreamNet can use this link to communicate with the Media Gateway and determine its location and hence the beam(s) the vessel is under.

Our SatstreamNet platform continuously monitors the location of each active receiver and the activity status of each media stream and it is able to determine which spot beams should be used for transmission and which ones should be de-activated. This information can be provided to the satellite transmission hub so that the Multicast IP traffic routes for each satellite beam can be configured or removed. With knowledge of the location of each vessel, a Multicast IP delivery service using SatstreamNet, will introduce significant efficiencies to a content delivery service operating over an HTS satellite. The efficiency will increase with an increasing number of vessels within the same spot beam as well as increases in content file size or live stream bandwidth. For more information about SatstreamNet, please contact us.