FIELD: radio engineering, communication.
SUBSTANCE: apparatus includes a processor configured to receive an unacknowledged mode message, initiate operation of a timer based on receipt of the unacknowledged mode message, re-initiate timer operation in response to each subsequent unacknowledged mode message received prior to expiration of the timer, record a timer expiry event in response to the timer expiring prior to receipt of a subsequent unacknowledged mode message, and indicate a data reception error in response to receipt of the subsequent unacknowledged mode message after recording the timer expiry event.
EFFECT: high accuracy of detecting ciphering errors.
21 cl, 7 dwg
