Patent ID: 7904714
Filing Date: 2011-03-08
Classification: H04L

Abstract:
1. A method for transmitting a signal by a signal transmission apparatus in a communication system, comprising the steps of: generating, by the signal transmission apparatus, second ciphering information using a frame number of the communication system and first ciphering information for data to be transmitted; ciphering, by the signal transmission apparatus, the data using the second ciphering information and third ciphering information; and generating, by the signal transmission apparatus, a signal that includes the ciphered data and only the first ciphering information among the first ciphering information, the second ciphering information, and the third ciphering information, and transmitting the generated signal, wherein the first ciphering information is a rollover counter (ROC), wherein the ROC increases as the frame number of the communication system increases, and wherein generating, by the signal transmission apparatus, the second ciphering information comprises: generating, by the signal transmission apparatus, the second ciphering information by concatenating the frame number of the communication system and the ROC, and repeating a concatenation result a preset number of times.