Patent ID: 7620184
Filing Date: 2009-11-17
Classification: H04L,H04W

Abstract:
1. A method for transmitting encrypted data between a sender mobile terminal and at least one receiver mobile terminal of a digital radiocommunication system, through a radio transmission channel having a frame structure such that a TDMA frame comprises time slots of a first type forming a traffic channel for the transmission of traffic information and at least one time slot of a second type forming an associated signaling channel for the transmission of signaling information, wherein a sequence of encrypted data packets is transmitted in the traffic channel starting from a determined time slot of the first type whereas an associated cryptographic synchronization information cue is periodically transmitted in the associated signaling channel inside a determined time slot of the second type which is timely separated from said time slot of the first type by an undetermined time gap, and wherein a cryptographic synchronization delay information cue relating to said time gap is also periodically transmitted in the associated signaling channel.