Codeword synthesizing system and a correlation system, methods of operation thereof and a spread spectrum communications transceiver employing the same
View Patent ↗A codeword synthesizing system and a correlation system for use with a spread spectrum communications system. In one embodiment, the codeword synthesizing system typically associated with a transmitter includes a base sequence generating subsystem, a modifier sequence generating subsystem and a concatenating subsystem. The base sequence generating subsystem is configured to create base sequences having a length less than a synthesized codeword. The modifier sequence generating subsystem is configured to create a modifier sequence, and the concatenating subsystem is configured to produce the synthesized codeword by multiplying each of the base sequences by an element of the modifier sequence. In one embodiment, the correlation system typically associated with a receiver includes a partial correlating subsystem, a memory subsystem and a combining subsystem. The partial correlating subsystem correlates base sequences of a synthesized codeword to a template and derives multiple partially correlated resultants. The memory subsystem temporarily stores the partially correlated resultants, and the combining subsystem sums weighted values of the partially correlated resultants to provide a correlated value of the synthesized codeword.
1. A codeword synthesizing system for use with a spread spectrum communications system, including:
a base sequence generating subsystem configured to create, at a first clock rate, base sequences of a synthesized codeword having a length less than said synthesized codeword, said synthesized codeword employed to encode a data bit to be transmitted via said spread spectrum communications system;
a modifier sequence generating subsystem configured to create, at a second clock rate, a modifier sequence having multiple elements;
a concatenating subsystem configured to produce said synthesized codeword by multiplying repetitions of said base sequences by a different one of said multiple elements, wherein each of said repetitions is inverted or not inverted based on said different one of said multiple elements to produce randomization of said base sequences within said synthesized codeword.
2. The codeword synthesizing system as recited in claim 1 wherein a length of each of said base sequences varies.
3. The codeword synthesizing system as recited in claim 1 wherein said modifier sequence generating subsystem is configured to create said modifier sequence employing a code selected from the group consisting of:
pseudo random noise (PRN),
Gold codes, and
Walsh codes.
4. The codeword synthesizing system as recited in claim 1 wherein said base sequence generating subsystem and said modifier sequence generating subsystem employ a memory device having a look-up table.
5. A method of synthesizing a codeword for use with a spread spectrum communications system, comprising:
generating, at a first clock rate, base sequences of a synthesized codeword having a length less than a length of said synthesized codeword, said synthesized codeword employed to encode a data bit to be transmitted via said spread spectrum communications system;
creating a modifier sequence having multiple elements at a second clock rate; and
multiplying repetitions of said base sequences by a different one of said multiple elements to produce said synthesized codeword, wherein each of said repetitions is inverted or not inverted based on said different one of said multiple elements to produce randomization of said base sequences within said synthesized codeword.
6. The method as recited in claim 5 wherein a length of each of said base sequences varies.
7. The method as recited in claim 5 wherein said synthesized codeword has a length based on a product of a length of one of said base sequences and a length of said modifier sequence.
8. The method as recited in claim 5 wherein said generating and said creating employ a memory device having a look-up table.
9. A correlation system for use with a spread spectrum communications system, comprising:
a partial correlating subsystem configured to correlate base sequences of a synthesized codeword to a template and derive multiple partially correlated resultants, wherein said synthesized codeword includes repetitions of said base sequences that are inverted or not inverted to produce randomization of said base sequences within said synthesized codeword, said synthesized codeword employed to encode a data bit to be transmitted via said spread spectrum communications system;
a memory subsystem configured to temporarily store said partially correlated resultants; and
a combining subsystem configured to sum weighted values of said partially correlated resultants to provide a correlated value of said synthesized codeword.
10. The correlation system as recited in claim 9 wherein said partial correlating subsystem is configured to correlate base sequences having a variable length.
11. The correlation system as recited in claim 9 wherein said partial correlating subsystem is configured to correlate base sequences having a length selected from the group consisting of:
about an eighth (⅛) of said synthesized codeword, and
about a fourth (¼) of said synthesized codeword.
12. The correlation system as recited in claim 9 wherein said memory subsystem employs random access memory.
13. The correlation system as recited in claim 9 wherein said correlation system is embodied within an field programmable gate array (FPGA).
14. A method of correlating a synthesized codeword for use with a spread spectrum communications system, comprising:
correlating base sequences of said synthesized codeword to a template and deriving multiple partially correlated resultants, wherein said synthesized codeword includes repetitions of said base sequences that are inverted or not inverted to produce randomization of said base sequences within said synthesized codeword, said synthesized codeword employed to encode a data bit to be transmitted via said spread spectrum communications system;
storing temporarily said multiple partially correlated resultants;
summing weighted values of said multiple partially correlated resultants to provide a correlated value of said synthesized codeword.
15. The method as recited in claim 14 wherein said base sequences have a variable length.
16. The method as recited in claim 14 wherein said base sequences have a length selected from the group consisting of:
about an eighth (⅛) of said synthesized codeword, and
about a fourth (¼) of said synthesized codeword.
17. The method as recited in claim 14 wherein said storing employs a random access memory.
18. The method as recited in claim 14 wherein said method is embodied within a field programmable gate array (FPGA).
19. A spread spectrum communications system transceiver, comprising:
an antenna;
a transmitter, including:
a codeword synthesizing system, including:
a base sequence generating subsystem configured to create, at a first clock rate, base sequences of a synthesized codeword associated with said transmitter having a length less than said synthesized codeword, said synthesized codeword employed to encode a data bit,
a modifier sequence generating subsystem configured to create, at a second clock rate, a modifier sequence having multiple elements, and
a concatenating subsystem configured to produce said synthesized codeword associated with said transmitter by multiplying repetitions of said created base sequences by a different one of said multiple elements, wherein each of said repetitions is inverted or not inverted based on said different one of said multiple elements to produce randomization of said created base sequences within said synthesized codeword associated with said transmitter; and
a receiver, including:
a correlation system, including:
a partial correlating subsystem configured to correlate received base sequences of a received synthesized codeword to a template and derive multiple partially correlated resultants, wherein said received synthesized codeword includes repetitions of said received base sequences that are inverted or not inverted to produce randomization of said received base sequences within said received synthesized codeword,
a memory subsystem configured to temporarily store said partially correlated resultants, and
a combining subsystem configured to sum weighted values of said partially correlated resultants to provide a correlated value of said received synthesized codeword.
20. The spread spectrum communications system transceiver as recited in claim 19 wherein said created base sequences or said received base sequences have a variable length.
21. The spread spectrum communications system transceiver as recited in claim 19 wherein said memory subsystem employs random access memory.
22. The spread spectrum communications system transceiver as recited in claim 19 wherein said correlation system is embodied in a field programmable gate array.
23. The spread spectrum communications system transceiver as recited in claim 19 wherein said base sequence generating subsystem and said modifier sequence generating subsystem employ a memory device having a look-up table.
24. The codeword synthesizing system as recited in claim 1 wherein said first clock rate is a chip clock rate and said second clock rate is said chip clock rate divided by a value representing said length.
25. The codeword synthesizing system as recited in claim 1 wherein said each of said repetitions of said base sequences generated by said generating subsystem is accompanied by changing an output of said modifier sequence generating subsystem to a next element in said modifier sequence.