Method and apparatus for rapid synchronization of shift register related symbol sequences
A sequence generator implemented on a receiver is synchronized with a sequence generator at a transmitter. The receiver receives k n-state symbols, with k>1 and n>1 wherein each of the k n-state symbols is associated with a generating state of the sequence generator at the transmitter. A processor in the receiver evaluates an n-state expression that generates an n-state symbol that is associated with a synchronized state of the receiver. Coefficients related to the n-state expression are stored on a memory and are retrieved by the processor. The synchronized state in one embodiment is part of a code hop. The sequence generator in the receiver may be part of a descrambler, of a communication device, of a data storage device and/or of an opening mechanism.
1. A method to synchronize a sequence generator determined by an n-state k-stage, shift register in a feedback configuration with n>1 and k>1, for generating at least one n-state symbol, each n-state symbol being represented by a signal, comprising:
receiving by a processor k non-consecutive n-state symbols in a sequence of n-state symbols, wherein none of the k non-consecutive n-state symbols is consecutive in the sequence of n-state symbols;
determining by the processor a generating state of the sequence generator for a starting moment, including the steps of executing k different n-state expressions wherein only the k non-consecutive n-state symbols as are variables; and
generating by the sequence generator of the at least one n-state symbol at the starting moment with the n-state k-stage, shift register in the feedback configuration in the generating state, wherein the sequence generator is an autonomous sequence generator.
2. The method of claim 1 , wherein n>2.
3. The method of claim 1 , wherein coefficients of the k different n-state n-state expressions are stored in a memory.
4. The method of claim 1 , further comprising:
the processor receiving data determining a configuration of the n-state k-stage shift register in the feedback configuration; and
the processor determining the k different n-state expressions from the at least k n-state symbols and the configuration of the n-state k-state shift register in the feedback configuration.
5. The method of claim 1 , wherein the sequence generator generates a sequence that is a combination of at least two sequences.
6. The method of claim 1 , wherein the generating state is part of a code hop.
7. The method of claim 1 , wherein the processor is part of a device that activates a mechanism.
8. The method of claim 1 , wherein the processor is part of a communication device.
9. An apparatus to synchronize a sequence generator determined by an n-state k-stage, shift register in a feedback configuration with n>1 and k>1, to generate at least one n-state symbol, each n-state symbol being represented by a signal, comprising:
a processor configured to perform the steps of: receiving k non-consecutive n-state symbols in a sequence of n-state symbols; determining a generating state of the sequence generator for a starting moment, including the steps of executing k different n-state expressions, wherein only the k non-consecutive n-state symbols as are variables; and
wherein the sequence generator generating the at least one n-state symbol at the starting moment with the n-state k-stage, shift register in the feedback configuration in the generating state, wherein the sequence generator is an autonomous sequence generator.
10. The apparatus of claim 9 , wherein n>2.
11. The apparatus of claim 9 , wherein coefficients of the k different n-state expressions are stored in a memory that is accessed by the processor.
12. The apparatus of claim 9 , wherein the processor synchronizes a receiver with a transmitter.
13. The apparatus of claim 9 , wherein the processor is part of a wireless receiver.
14. The apparatus of claim 9 , wherein the sequence generator is a selected from the group that consists of a Gold sequence generator and a Kasami sequence generator.
15. The apparatus of claim 9 , wherein the processor is part of a communication device.
16. The apparatus of claim 9 , wherein the processor performs a code hop.
17. The apparatus of claim 9 , wherein the processor is part of a data storage device.
18. The method of claim 1 , wherein an initiation of determining the generating state is based on a prediction of at least one of a received n-state symbol in the sequence of n-state symbols.
19. The apparatus of claim 9 , wherein an initiation of determining the generating state is based on a prediction of at least one of a received n-state symbol in the sequence of n-state symbols.