US6091761A
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Despreading method and arrangement in communication system
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1998-01-16
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Granted: 2000-07-18
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Expires: 2018-01-16
Abstract
Abstract The invention relates to a method and an arrangement for implementing a bank of correlators, corresponding to a set of Orthogonal Gold codes, in a receiver used in a Direct Sequence Code Division Multiple Access system (DS-CDMA). The bank of correlators generates N correlation values (CV0, . . . , CVN-1) from N received symbols (s0, s1, . . . , sN-1) in a sequence. The received symbol sequence (s0, s1, . . . , sN-1), where each symbol has been spread by an Orthogonal Gold code respectively, is buffered (401). The buffered symbol sequence is multiplied (402) element-by-element with an arbitrary sequence (a0, a1, . . . , aN-1), in order to obtain a set of products (s0*a0, s1*a1, . . . , sN-1*aN-1). Said arbitrary sequence is the same sequence used when generating the Orthogonal Gold Codes. The set of products (s0*a0, s1*a1, . . . , sN-1*aN-1) is then permuted (403) in order to obtain a sequence, which is equal to a sum of a number of sequences from a set of Walsh sequences. The sequence is then transformed (404) with Fast Hadamard Transform as to obtain said correlation values (CV0, . . . , CVN-1)
Inventors
- 👤 Branislav Popovic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:40
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/709; H04J; H04J13/00; H04J13/0007; H04J13/004; H04J13/0051
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
214 words
A method of despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of correlation values (CV 0 , . . . , CV N-1 ), where said symbol sequence has been spread by a set of Orthogonal Gold sequences (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), comprising the following steps: a) multiplying element-by-element said symbol sequence (s 0 , s 1 , . . . , s N-1 ) with said arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), in order to obtain a set of products (s 0 *a 0 , s 1 *a 1 , . . . , s N-1 *a N-1 ); b) permuting said set of products (s 0 *a 0 , s 1 *a 1 , . . . , s N-1 *a N-1 ) in order to obtain a sequence (w) equal to a sum of a number of sequences from a set of Walsh sequences; c) transforming said sequence (w) with a Fast Hadamard Transform to obtain said correlation values (CV 0 , . . . , CV N-1 ).
Claim 2
Independent Claim
214 words
A method of despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of correlation values (CV 0 , . . . , CV N-1 ), where said symbol sequence has been spread by a set of Orthogonal Gold sequences (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), comprising the following steps: a) multiplying element-by-element said symbol sequence (s 0 , s 1 , . . . , s N-1 ) with said arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), in order to obtain a set of products (s 0 *a 0 , s 1 *a 1 , . . . , s N-1 *a N-1 ); b) permuting said set of products (s 0 *a 0 , s 1 *a 1 , . . . , s N-1 *a N-1 ) in order to obtain a sequence (w) equal to a sum of a number of sequences from a set of Walsh sequences; c) transforming said sequence (w) with a Fast Hadamard Transform to obtain said correlation values (CV 0 , . . . , CV N-1 ).
Claim 3
Dependent Claim
45 words
A method according to claim 1, wherein the element-by-element multiplications are performed in parallel and the method further comprises the step of performing a serial to parallel conversion on said symbol sequence (s 0 , s 1 , . . . , s N-1 ).
Claim 4
Dependent Claim
35 words
A method according to claim 1, wherein the element-by-element multiplications are performed serially and the method further comprises buffering said symbol sequence (s 0 , s 1 , . . . , s N-1 ).
Claim 5
Dependent Claim
28 words
A method according to claim 1, wherein said arbitrary sequence (a 0 , a 1 , . . . , a N-1 ) is a maximal-length PN sequence.
Claim 6
Independent Claim
261 words
A method of despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of correlation values (CV 0 , . . . , CV N-1 ), where said symbol sequence has been spread by a set of Orthogonal Gold sequences (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), comprising the following steps: a) permuting said symbol sequence (s 0 , s 1 , . . . , s N-1 ), according to a certain rule in order to obtain a permuted version (s p0 , s p1 , . . . , s pN-1 )of the symbol sequence; b) permuting said arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), according to the certain rule in order to obtain a permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence; c) multiplying element-by-element said permuted version (s p0 , s p1 , . . . , s pN-1 ) of the symbol sequence with said permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence, to obtain a sequence (w) equal to a sum of a number of sequences from a set of Walsh sequences; d) transforming said sequence (w) with a Fast Hadamard Transform to obtain said correlation values (CV 0 , . . . , CV N-1 ).
Claim 7
Independent Claim
261 words
A method of despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of correlation values (CV 0 , . . . , CV N-1 ), where said symbol sequence has been spread by a set of Orthogonal Gold sequences (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), comprising the following steps: a) permuting said symbol sequence (s 0 , s 1 , . . . , s N-1 ), according to a certain rule in order to obtain a permuted version (s p0 , s p1 , . . . , s pN-1 )of the symbol sequence; b) permuting said arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), according to the certain rule in order to obtain a permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence; c) multiplying element-by-element said permuted version (s p0 , s p1 , . . . , s pN-1 ) of the symbol sequence with said permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence, to obtain a sequence (w) equal to a sum of a number of sequences from a set of Walsh sequences; d) transforming said sequence (w) with a Fast Hadamard Transform to obtain said correlation values (CV 0 , . . . , CV N-1 ).
Claim 8
Independent Claim
305 words
A method of despreading a first symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of code channels (CH 0 , CH 1 , . . . , CH M ) from an incoming code spread radio signal, which is quadrature detected to obtain an inphase signal and a quadrature signal, comprising the following steps: correlating said inphase signal to obtain N inphase correlation values by performing the steps of; sampling the inphase signal to obtain a second symbol sequence; multiplying the second symbol sequence element-by-element with an arbitrary sequence to obtain a first set of products; permuting the first set of products to obtain a first permuted sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the first permuted sequence with a Fast Hadamard Transform; correlating said quadrature signal to obtain N quadrature correlation values by performing the steps of; sampling the quadrature signal to obtain a third symbol sequence; multiplying the third symbol sequence element-by-element with the arbitrary sequence to obtain a second set of products; permuting the second set of products to obtain a second permuted sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the second permuted sequence with a Fast Hadamard Transform; and arranging said inphase correlation values and said quadrature correlation values according to a corresponding spreading method, therewith to obtain said code channels (CH 0 , CH 1 , . . . , CH M ) from an incoming code spread radio signal, which is quadrature detected to obtain an inphase signal and a quadrature signal; wherein the first symbol sequence has been spread using a set of Orthogonal Gold sequences generated using the arbitrary sequence.
Claim 9
Independent Claim
305 words
A method of despreading a first symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of code channels (CH 0 , CH 1 , . . . , CH M ) from an incoming code spread radio signal, which is quadrature detected to obtain an inphase signal and a quadrature signal, comprising the following steps: correlating said inphase signal to obtain N inphase correlation values by performing the steps of; sampling the inphase signal to obtain a second symbol sequence; multiplying the second symbol sequence element-by-element with an arbitrary sequence to obtain a first set of products; permuting the first set of products to obtain a first permuted sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the first permuted sequence with a Fast Hadamard Transform; correlating said quadrature signal to obtain N quadrature correlation values by performing the steps of; sampling the quadrature signal to obtain a third symbol sequence; multiplying the third symbol sequence element-by-element with the arbitrary sequence to obtain a second set of products; permuting the second set of products to obtain a second permuted sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the second permuted sequence with a Fast Hadamard Transform; and arranging said inphase correlation values and said quadrature correlation values according to a corresponding spreading method, therewith to obtain said code channels (CH 0 , CH 1 , . . . , CH M ) from an incoming code spread radio signal, which is quadrature detected to obtain an inphase signal and a quadrature signal; wherein the first symbol sequence has been spread using a set of Orthogonal Gold sequences generated using the arbitrary sequence.
Claim 10
Dependent Claim
46 words
A method according to claim 6, wherein: said spreading method is Binary Phase Shift Keying (BPSK) spreading, and the number of obtained code channels (CH 0 , CH 1 , . . . , CH M ) is equal to the number of obtained correlation values.
Claim 11
Dependent Claim
48 words
A method according to claim 6, wherein: said spreading method is QuadraPhase Shift Keying (QPSK) spreading, and the number of obtained code channels (CH 0 , CH 1 , . . . , CH M ) is equal to half of the number of the obtained correlation values.
Claim 12
Independent Claim
358 words
A method of despreading a first symbol sequence (s p0 , s p1 , . . . , s pN-1 ), to obtain a number of code channels (CH 0 , CH 1 , . . . , CH M ) from an incoming code spread radio signal, which is quadrature detected to obtain an inphase signal and a quadrature signal, comprising the following steps: correlating said inphase signal to obtain N inphase correlation values by performing the steps of; sampling the inphase signal to obtain a second symbol sequence; permuting the second symbol sequence according to a first rule in order to obtain a permuted version of the second symbol sequence; permuting an arbitrary sequence according to the first rule in order to obtain a permuted version of the arbitrary sequence; multiplying the permuted version of the second symbol sequence with the permuted version of the arbitrary sequence element-by-element to obtain a first multiplied sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the first multiplied sequence with a Fast Hadamard Transform; correlating said quadrature signal to obtain N quadrature correlation values by performing the steps of; sampling the quadrature signal to obtain a third symbol sequence; permuting the third symbol sequence according to a second rule in order to obtain a permuted version of the third symbol sequence; permuting the arbitrary sequence according to the second rule in order to obtain a permuted version of the arbitrary sequence; multiplying the permuted version of the third symbol sequence with the permuted version of the arbitrary sequence element-by-element to obtain a second multiplied sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the second multiplied sequence with a Fast Hadamard Transform; arranging said inphase correlation values and said quadrature correlation values according to a corresponding spreading method, therewith to obtain said code channels (CH 0 , CH 1 , . . . , CH M ); wherein the first symbol sequence has been spread using a set of Orthogonal Gold sequences generated using the arbitrary sequence.
Claim 13
Independent Claim
358 words
A method of despreading a first symbol sequence (s p0 , s p1 , . . . , s pN-1 ), to obtain a number of code channels (CH 0 , CH 1 , . . . , CH M ) from an incoming code spread radio signal, which is quadrature detected to obtain an inphase signal and a quadrature signal, comprising the following steps: correlating said inphase signal to obtain N inphase correlation values by performing the steps of; sampling the inphase signal to obtain a second symbol sequence; permuting the second symbol sequence according to a first rule in order to obtain a permuted version of the second symbol sequence; permuting an arbitrary sequence according to the first rule in order to obtain a permuted version of the arbitrary sequence; multiplying the permuted version of the second symbol sequence with the permuted version of the arbitrary sequence element-by-element to obtain a first multiplied sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the first multiplied sequence with a Fast Hadamard Transform; correlating said quadrature signal to obtain N quadrature correlation values by performing the steps of; sampling the quadrature signal to obtain a third symbol sequence; permuting the third symbol sequence according to a second rule in order to obtain a permuted version of the third symbol sequence; permuting the arbitrary sequence according to the second rule in order to obtain a permuted version of the arbitrary sequence; multiplying the permuted version of the third symbol sequence with the permuted version of the arbitrary sequence element-by-element to obtain a second multiplied sequence that is equal to a sum of a number of sequences from a set of Walsh sequences; and transforming the second multiplied sequence with a Fast Hadamard Transform; arranging said inphase correlation values and said quadrature correlation values according to a corresponding spreading method, therewith to obtain said code channels (CH 0 , CH 1 , . . . , CH M ); wherein the first symbol sequence has been spread using a set of Orthogonal Gold sequences generated using the arbitrary sequence.
Claim 14
Dependent Claim
280 words
An arrangement of a bank of correlators for despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of code channels (CH 0 , CH 1 , . . . , CH N-1 ), where the code channels have been spread by a set of Orthogonal Gold sequence (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ) said arrangement comprising: means for permuting the symbol sequence (s 0 , s 1 , . . . , s N-1 )according to a certain rule, in order to obtain a permuted version (s p0 , s p1 , . . . , s pN-1 ) of the symbol sequence; means for permuting the arbitrary sequence (a 0 , a 1 , . . . , a N-1 ) according to the certain rule, in order to obtain a permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence; means for multiplying element-by-element said permuted version (s p0 , s p1 , . . . , s pN-1 ) of the symbol sequence with said permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence to obtain a sequence (w) which is a sum of a number of sequences from a set of Walsh sequences; and at least one bank of Walsh correlators, implemented as a Fast Hadamard Transformer, operable to transform said sequence (w) to obtain correlation values (CV 0 , . . . , CV N-1 ).
Claim 15
Dependent Claim
280 words
An arrangement of a bank of correlators for despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 ) to obtain a number of code channels (CH 0 , CH 1 , . . . , CH N-1 ), where the code channels have been spread by a set of Orthogonal Gold sequence (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ) said arrangement comprising: means for permuting the symbol sequence (s 0 , s 1 , . . . , s N-1 )according to a certain rule, in order to obtain a permuted version (s p0 , s p1 , . . . , s pN-1 ) of the symbol sequence; means for permuting the arbitrary sequence (a 0 , a 1 , . . . , a N-1 ) according to the certain rule, in order to obtain a permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence; means for multiplying element-by-element said permuted version (s p0 , s p1 , . . . , s pN-1 ) of the symbol sequence with said permuted version (a p0 , a p1 , . . . , a pN-1 ) of the arbitrary sequence to obtain a sequence (w) which is a sum of a number of sequences from a set of Walsh sequences; and at least one bank of Walsh correlators, implemented as a Fast Hadamard Transformer, operable to transform said sequence (w) to obtain correlation values (CV 0 , . . . , CV N-1 ).
Claim 16
Dependent Claim
230 words
An arrangement of a bank of correlators for despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 )to obtain a number of code channels (CH 0 , CH, . . . , CH N-1 ), where the code channels have been spread by a set of Orthogonal Gold sequences (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), said arrangement comprising: means for multiplying element-by-element said symbol sequence (s 0 , s 1 , . . . , s N-1 ) with said arbitrary sequence (a 0 , a 1 , . . . , a N-1 ) to obtain a set of products (s 0 *a, s 1 *a 1 , . . . , s N-1 *a N-1 ); means for permuting said set of products (s 0 *a 0 , s 1 *a 1 , . . . , s N-1 *a N-1 ) according to a certain rule, in order to obtain a sequence (w) which is a sum of a number of sequences from a set of Walsh sequences; and at least one bank of Walsh correlators, implemented as a Fast Hadamard Transformer, operable to transform said sequences (w) to obtain correlation values (CV 0 , . . . , CV N-1 ).
Claim 17
Dependent Claim
230 words
An arrangement of a bank of correlators for despreading a symbol sequence (s 0 , s 1 , . . . , s N-1 )to obtain a number of code channels (CH 0 , CH, . . . , CH N-1 ), where the code channels have been spread by a set of Orthogonal Gold sequences (G), which have been generated by means of an arbitrary sequence (a 0 , a 1 , . . . , a N-1 ), said arrangement comprising: means for multiplying element-by-element said symbol sequence (s 0 , s 1 , . . . , s N-1 ) with said arbitrary sequence (a 0 , a 1 , . . . , a N-1 ) to obtain a set of products (s 0 *a, s 1 *a 1 , . . . , s N-1 *a N-1 ); means for permuting said set of products (s 0 *a 0 , s 1 *a 1 , . . . , s N-1 *a N-1 ) according to a certain rule, in order to obtain a sequence (w) which is a sum of a number of sequences from a set of Walsh sequences; and at least one bank of Walsh correlators, implemented as a Fast Hadamard Transformer, operable to transform said sequences (w) to obtain correlation values (CV 0 , . . . , CV N-1 ).
References Cited (Backward Citations)
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