CERONA SAMA TECHNOLOGY

Spread Aloha Multiple Access (SAMA)

SAMA represents a breakthrough in the implementation of shared use of satellite bandwidth for VSAT networks.  Using a combination of spread spectrum techniques in conjunction with slotted Aloha multiple access techniques, Cerona’s SAMA provides tremendous advantages.  These advantages include the following:

• Unparalleled mobility - Cerona’s SAMA, through the use of spread spectrum technology, spreads out the data transmissions over a wide portion of the radio spectrum.  Because of this, the risk of interference to adjacent satellites (satellites are typically spaced 2 degrees apart in the sky) from the intended satellite is greatly reduced.  It also permits the use of phased array antennas or very small parabolic systems.  In other systems these antennae suffer from substantial issues with side lobes causing interference to adjacent satellites.  In its spread spectrum system Cerona eliminates this problem and further enhances the system reliability by working in conjunction with phased array antennas or gimbal mounted parabolic antennas that can be steered electronically in the fraction of a second, thus maintaining broadband communications in rapidly moving vehicles that are encountering bumps, air turbulence, or other harsh terrains.  This is particularly important for military “Comms-On-The Move” (COTM) applications but also applies to many commercial environments such as marine, rail and first responder requirements.

• Greater number of terminals per transponder - Depending on the type of communications traffic, Cerona’s SAMA technique can support up to 60,000 terminals per transponder, compared to the practical observed limit of ~9,000 achieved with current deployed TDMA satellite networks.  This can significantly lower the cost of the satellite bandwidth for a satellite network, thus reducing total cost of ownership for the network operator.  

• Reduced latency - Due to it connectionless format, which eliminates the time required for assigning a channel to a terminal, the latency for a properly loaded  SAMA network is 530 milliseconds, as compared to typical ranges of 510-2100 milliseconds for competing designs.  This is particularly important for Internet traffic that is “bursty” such as users typing on keyboards, or speaking into VoIP handsets. For these users, latency means poor performance.  A better solution is Cerona’s connection free packet bursts which uses the satellite channel only when needed, rather than a circuit based approach which reserves satellite capacity even when there are no packets to send.

• Smaller Antennas  - Spread spectrum means that spectral density is lower than TDMA alternatives.  This allows the link budget to be closed on the return channel with a smaller antenna.  Many factors such as location, frequency band, HPA power are also key but when stacked up to other technologies SAMA networks allow for smaller antennas.

Cerona’s SAMA technology is found in the company’s SkyDSL VSAT units and the RangeRunner hub, which are used in conjunction with the remote terminals.