Data from a transmitter is extended to include authentication data on the application level by an application protocol. The authentication data is used by the receiver to determine whether the transmitter is known by the receiver. If the transmitter is known by the receiver, the data is accepted. If...http://www.google.co.uk/patents/US7266682?utm_source=gb-gplus-sharePatent US7266682 - Method and system for transmitting data from a transmitter to a receiver and transmitter and receiver therefor
