Abstract: Methods for cryptographic synchronization of data packets. A roll-over counter (ROC) value is periodically appended to and transmitted with a data packet when a function of the packet sequence number equals a predetermined value. The ROC effectively synchronizes the cryptographic transformation of the data packets. Although the disclosed methods are generally applicable to many transmission protocols, they are particularly adaptable for use in systems wherein the data packets are transmitted to a receiver using the Secure Real-Time Transport Protocol (SRTP) as defined in Internet Engineering Task Force (IETF) Request for Comments (RFC) 3711.

Abstract: An error detection unit performs erasure decoding for physical layer packets and an assembler assembles the received data into higher layer packets. Higher layer packets that are incomplete are not erased if the higher layer packets contain some data indicated as valid by the error detection unit. In the case of incomplete packets, the data is labeled by assigning a value to a reliability attribute for the data to enable the decoder to discriminate between valid and invalid data in the same packet. The decoder is modified to use “dimmed” data from the incomplete packets to perform decoding.

Abstract: A mobile station downloading an object over a broadcast channel uses a repair service to obtain data that was received in error during the original broadcast. The mobile station sets a repair threshold for the download object and invokes repair if the amount of errors is less than the repair threshold. If the amount of errors exceeds the repair threshold, the mobile station treats the download attempt as having failed and may send a new request if download is still desired.

Abstract: A mobile radiocommunications terminal contains or is operatively connected to a position estimator, such as a GPS receiver. The mobile terminal stores at least one reference position. The mobile terminal updates its position at a frequency that is a function of its distance from the reference position, or as a function of the rate of change of its distance from the reference position.