Rake receiver for a CDMA system, in particular incorporated in a cellular mobile phone
First Claim
Patent Images
1. A digital N-finger rake receiver for a code-division multiple access (CDMA) system comprising:
- input means for receiving a digital scrambled and spread signal containing chips having a duration Tc, oversampled with an oversampling factor Ns, and including delayed versions of at least one initial signal scrambled with at least one scrambling code, spread with at least one orthogonal code and transmitted by at least one emitter on a multipath transmission channel having a predetermined maximum delay spread Ds;
estimation means connected to said input means for estimating a number of paths of the multipath transmission channel and respective time delay values associated therewith; and
processing means for time aligning and descrambling, despreading, and combining the delayed versions of the at least one initial signal for delivering a data stream contained therein, said processing means comprising a time aligning and descrambling unit comprising a first delay chain connected to said input means and having N1 first outputs with a delay value between two adjacent first outputs equal to Tc/Ns, and with N1 equal to at least Ns+1, at least one phase controllable scrambling code generator for generating at least one phase scrambling code of the at least one initial signal, at least one second delay chain connected to an output of said at least one phase controllable scrambling code generator, and having 1+Ds/Tc second outputs with a delay value between two adjacent second outputs equal to Tc, first controllable selection means for selecting, for each path, one of the first outputs based upon a first control signal, second controllable selection means for selecting, for each path, one of the second outputs based upon a second control signal, and multiplication means for multiplying, for each path, a first signal at a selected first output with a second signal at a selected second output, and control means for delivering the first and second control signals for each path based upon the respective time delay value of the path being considered.
1 Assignment
0 Petitions
Accused Products
Abstract
A rake receiver uses a delayed version of the received sequence and a delayed version of a scrambling code. The flexible hardware structure of the time-aligning and descrambling unit includes at least two delay chains and one multiplier. By controlling two multiplexers, the delayed versions of the received sequence can be multiplied with an arbitrary scrambling code having an arbitrary phase. During one chip period, one multiplication is performed for each path to be processed.
-
Citations
39 Claims
-
1. A digital N-finger rake receiver for a code-division multiple access (CDMA) system comprising:
-
input means for receiving a digital scrambled and spread signal containing chips having a duration Tc, oversampled with an oversampling factor Ns, and including delayed versions of at least one initial signal scrambled with at least one scrambling code, spread with at least one orthogonal code and transmitted by at least one emitter on a multipath transmission channel having a predetermined maximum delay spread Ds;
estimation means connected to said input means for estimating a number of paths of the multipath transmission channel and respective time delay values associated therewith; and
processing means for time aligning and descrambling, despreading, and combining the delayed versions of the at least one initial signal for delivering a data stream contained therein, said processing means comprising a time aligning and descrambling unit comprising a first delay chain connected to said input means and having N1 first outputs with a delay value between two adjacent first outputs equal to Tc/Ns, and with N1 equal to at least Ns+1, at least one phase controllable scrambling code generator for generating at least one phase scrambling code of the at least one initial signal, at least one second delay chain connected to an output of said at least one phase controllable scrambling code generator, and having 1+Ds/Tc second outputs with a delay value between two adjacent second outputs equal to Tc, first controllable selection means for selecting, for each path, one of the first outputs based upon a first control signal, second controllable selection means for selecting, for each path, one of the second outputs based upon a second control signal, and multiplication means for multiplying, for each path, a first signal at a selected first output with a second signal at a selected second output, and control means for delivering the first and second control signals for each path based upon the respective time delay value of the path being considered. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A rake receiver or a code-division multiple access (CDMA) system comprising:
-
an input stage for receiving a digital scrambled and spread signal containing chips from a multipath transmission channel;
an estimation circuit connected to said input stage for estimating a number of paths of the multipath transmission channel;
a time aligning and descrambling unit connected to said input stage and comprising a first delay chain connected to said input stage and having a plurality of first outputs, at least one phase controllable scrambling code generator for generating a phase scrambling code of at least one initial signal, at least one second delay chain connected to an output of said at least one phase controllable scrambling code generator and having a plurality of second outputs, a first controllable selector for selecting, for each path, one of the first outputs of said first delay chain based upon a first control signal, a second controllable selector for selecting, for each path, one of the second outputs of said at least one second delay chain based upon a second control signal, and at least one multiplier connected to said first and second controllable selectors for multiplying, for each path, a signal at a selected first output of said first delay chain with a signal at a selected second output of said at least one second delay chain. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
-
-
22. A cellular mobile phone comprising:
-
a front end for receiving a digital scrambled and spread signal containing chips having a duration Tc, oversampled with an oversampling factor Ns, and including delayed versions of at least one initial signal scrambled with at least one scrambling code, spread with at least one orthogonal code and transmitted by at least one emitter on a multipath transmission channel having a predetermined maximum delay spread Ds; and
a processing stage connected to said front end stage and comprising an estimation circuit connected to said front end stage for estimating a number of paths of the multipath transmission channel and respective time delay values associated therewith; and
a time aligning and descrambling unit connected to said front end for delivering data contained in the at least one initial signal and comprising a first delay chain connected to said front end and having N1 first outputs with a delay value between two adjacent first outputs equal to Tc/Ns, and N1 is equal to at least Ns+1, at least one phase controllable scrambling code generator for generating at least one scrambling code of the at least one initial signal, at least one second delay chain connected to an output of said at least one phase controllable scrambling code generator, and having 1+Ds/Tc second outputs with delay value between two adjacent second outputs equal to Tc, a first controllable selector or selecting, for each path, one of the first outputs based upon a first control signal, a second controllable selector for selecting, for each path, one of the second outputs based upon a second control signal, and at least one multiplier for multiplying, for each path, a first signal at a selected first output with a second signal at a selected second output, and a control circuit for delivering the first and second control signals for each path based upon the respective time delay value of the path being considered. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
-
-
35. A method for processing a digital signal for a code-division multiple access (CDMA) system, with the digital scrambled and spread signal containing chips from a multipath transmission channel, the method comprising:
-
estimating a number of paths of the multipath transmission channel and respective time delay values associated therewith;
applying the digital signal to a first delay chain having a plurality of first outputs, generating at least one scrambling code of at least one initial signal;
applying the at least one scrambling code to at least one second delay chain having a plurality of second outputs;
selecting, for each path, one of the plurality of first outputs of the first delay chain based upon a first control signal;
selecting, for each path, one of the plurality of second outputs of said at least one second delay chain based upon a second control signal;
multiplying, for each path, a signal at selected first output of the first delay chain with a signal at a selected second output of the at least one second delay chain; and
delivering the first and second control signals for each path based upon the respective time delay value of the path being considered. - View Dependent Claims (36, 37, 38, 39)
-
Specification