Method for updating linear feedback shift register of code generater


Application Number: 00108198
Application Date: 2000.05.10
Publication Number: 1273460
Publication Date: 2000.11.15
Priority Information: 1999/5/10 FI 991073
International: H03M7/30;H04J13/02
Applicant(s) Name: Nokia Mobile Phones Ltd.
Address:
Inventor(s) Name: E. Niminan (FI )
Patent Agency Code: 72001
Patent Agent: luan bensheng
Abstract The invention relates to three different methods for updating a linear feedback shift register of a code generator, and code generators applying the methods. In the basic method a Galois-type linear feedback shift register of a code generator is updated to a target state which is at a known offset from a unit state. The basic method comprises the following: generating a binary offset number illustrating the offset; generating a counter showing the number of bits in the binary offset number; initializing a temporary state with the unit state; iterating as long as the counter value is higher than zero: (310) multiplying the temporary state by itself by applying a Galois Field multiplication; (312) shifting the temporary state one state forward from the current temporary state if the value of the bit shown by the counter is one; and (314) decrementing the counter value by one; in the end, when the counter has reached the value zero, setting the temporary state as the target state.