摘要:
A method and apparatus for generating a code after a random time in a communication system using an n-stage Linear Feedback Shift Register (LFSR) are provided. The method includes expressing an element indicating the current state value of the LFSR in a finite field GF(2n), performing a 2r-th power operation and a multiply operation with respect to the characteristic polynomial using the LFSR when n=rs in the GF(2n), and repeating the 2r-th power operation and the multiply operation s times to calculate a new state value of the LFSR after the random time, thereby generating the code.
摘要:
A method and apparatus are provided for generating a code by quickly computing a state of a Linear Feedback Shift Register (LFSR) in a mobile communication system, in which a code for the communication system is generated including an n-stage LFSR and operating in sleep mode and active mode set at a preset time interval from the sleep mode. Current state values of the LFSR are combined with n different mask patterns such that the current state values are shifted by {20,21, . . . ,2n−1}. A combination result is provided as a new state value of the LFSR at an arbitrary time variably set in the sleep mode. To transform a current state value of the LFSR to a new state value after an arbitrary time, the code generation method employs a square and multiply algorithm without use of mask patterns.