Globalstar Product Management – Technical Support

How Secure Are Globalstar Calls

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Question:What technical features make the interception of a Globalstar call difficult? What about the level of security during a handover?

Answer:Globalstar is a commercial system which has been based on the robustness of Code Division Multiple Access (CDMA), an implementation of direct sequence spread spectrum techniques based on the IS-95 terrestrial cellular protocol. Voice and data communications use special codes to spread the low rate communications over a 1.23 MHz frequency band. In order to receive this information, the receiver must be time synchronized with the transmitter and must know which codes to use to “de-spread” the communications. Intercepting this data is considered to be extremely difficult, not only because the data is spread using an unknown code, but also because the power level of the call is very low, comparable with the level of ambient electro-magnetic noise and is embedded in other calls sharing the same frequency channel (typically 30-40 calls). These Low-Probability-of-Intercept (LPI) features which are inherent with the CDMA waveform provide over-the-air security between the User Terminal and the Gateway.

Handoffs are handled with the same security as any signaling channel function – call set-up, authentication, traffic circuit CDMA code assignment, etc. The signaling data about the user is encrypted – ID and dialed digits, etc. – so that the true identity or activity of the user is not divulged over the air.

Since Globalstar supports data communications, it is feasible for subscribers requiring additional guaranteed privacy to make use of external encryption devices to protect the end-to-end communications.

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Written by Joseph Crowley

August 16, 2008 at 6:04 am

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