US5914943A
Expired / Lapsed
US
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Apparatus and method for establishing acquisition of spreading code in CDMA transmission system
Assignee: NTT Docomo Inc
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Filing: 1995-12-27
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Granted: 1999-06-22
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Expires: 2015-12-27
Abstract
Abstract A CDMA system capable of quickly establishing acquisition of a long code, a spreading code with a period considerably longer than a symbol length. The received phase of the long code is estimated by inserting an a priori code into a spread signal which is spread by the long code at a fixed interval, and by detecting the start timing of receiving the a priori code, where the a priori code has a correlation value of nearly zero with the long code, and an autocorrelation value of a triangular profile. Its transmitter has an a priori code inserting circuit, and its receiver has a replica generating circuit of the a priori code. In addition, the system includes a plurality of correlators for obtaining correlation values between the received signal and the replica of the a priori code, and a circuit for obtaining the maximum correlation values and their start timings of reception among these correlation values. It estimates the start timing of the a priori code from the start timings of reception that provides the maximum correlation values, and estimates the point separated by a fixed time from the estimated start timing to be the received phase of the long code.
Inventors
- 👤 Kenichi Higuchi
- 👤 Mamoru Sawahashi
- 👤 Fumiyuki Adachi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:49
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7073; H04B1/7075; H04J; H04J13/00; H04J13/0077; H04B1/70757; H04B1/7077; H04B1/708; H04J3/00; H04J3/02; H04J3/06; H04J3/0602; H04B1/709; H04B1/7095; H04J13/0003
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
106 words
A transmitter in a CDMA transmission system comprising: long code generating means for generating a long code which is a spreading code with a period longer than information symbol; spreading means for generating a wideband spread signal by spreading transmission information using said long code; a priori code generating means for generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; a priori code insertion means for inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; and transmission means for transmitting said frames.
Claim 2
Dependent Claim
106 words
A transmitter in a CDMA transmission system comprising: long code generating means for generating a long code which is a spreading code with a period longer than information symbol; spreading means for generating a wideband spread signal by spreading transmission information using said long code; a priori code generating means for generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; a priori code insertion means for inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; and transmission means for transmitting said frames.
Claim 3
Dependent Claim
26 words
The transmitter in the CDMA transmission system as claimed in claim 1, wherein said a priori code comprises smoothly changing autocorrelation values, and a zero-cross point.
Claim 4
Dependent Claim
25 words
The transmitter in the CDMA transmission system as claimed in claim 1, wherein said autocorrelation values of said a priori code have a triangular profile.
Claim 5
Dependent Claim
21 words
The transmitter in the CDMA transmission system as claimed in claim 1, wherein said a priori code has a stepwise profile.
Claim 6
Dependent Claim
25 words
The transmitter in the CDMA transmission system as claimed in claim 1, wherein said a priori code has a period shorter than said long code.
Claim 7
Dependent Claim
37 words
The transmitter in the CDMA transmission system as claimed in claim 1, wherein said a priori code insertion means inserts said a priori code into said spread signal within a predetermined range at a beginning of communications.
Claim 8
Dependent Claim
71 words
The transmitter in the CDMA transmission system as claimed in claim 1, wherein said a priori code generating means comprises means for generating a predetermined code for a convolution, and calculation means for carrying out said convolution between said code for a convolution and said long code to output said a priori code, and said a priori code insertion means inserts an output of said calculation means into said spread signal.
Claim 9
Dependent Claim
175 words
An acquisition apparatus of a spreading code in a CDMA transmission system which demodulates desired information by receiving a received signal including a spread signal and an a priori code, said spread signal being spread by a long code which is a spreading code with a period longer than information symbol, said a priori code having a negligibly small cross-correlation with said long code, and representing a phase of said long code, said acquisition apparatus comprising: first correlation means for generating a replica of said long code, and for calculating a correlation between said received signal and said replica of said long code; second correlation means for generating a replica of said a priori code, and for calculating a correlation between said received signal and said replica of said a priori code; phase estimation means for estimating received phase of said long code based on an output of said second correlation means; and means for controlling a generation phase of said replica of said long code based on an output of said phase estimation means.
Claim 10
Dependent Claim
175 words
An acquisition apparatus of a spreading code in a CDMA transmission system which demodulates desired information by receiving a received signal including a spread signal and an a priori code, said spread signal being spread by a long code which is a spreading code with a period longer than information symbol, said a priori code having a negligibly small cross-correlation with said long code, and representing a phase of said long code, said acquisition apparatus comprising: first correlation means for generating a replica of said long code, and for calculating a correlation between said received signal and said replica of said long code; second correlation means for generating a replica of said a priori code, and for calculating a correlation between said received signal and said replica of said a priori code; phase estimation means for estimating received phase of said long code based on an output of said second correlation means; and means for controlling a generation phase of said replica of said long code based on an output of said phase estimation means.
Claim 11
Dependent Claim
140 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 8, wherein said a priori code is inserted into said spread signal at a fixed period, and wherein said second correlation means comprises paired correlators consisting of a correlator that generates replicas of paired a priori codes consisting of a replica of a first a priori code and a replica of a second a priori code with their correlation detection start timings shifted by an amount of Δ, and that calculates correlations between said replica of said first a priori code and said received signal, and a correlator that calculates correlations between said replica of said second a priori code and said received signal; and said phase estimation means estimates a received phase of said long code based on outputs of said paired correlators.
Claim 12
Dependent Claim
63 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 9, wherein each of said paired correlators integrates a product of said received signal and said replica of said a priori code for one period of said a priori code; and said phase estimation means estimates a received phase of said long code from two integrated values.
Claim 13
Dependent Claim
69 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 9, wherein said second correlation means comprises m pairs of correlators, where m is an integer greater than one, and wherein start timings of correlation detection and integration of adjacent pairs of said correlators are shifted by T A /m in time, where T A is a length of said a priori code.
Claim 14
Dependent Claim
53 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 9, wherein said phase estimation means comprises means for selecting one pair of said correlators which produces maximum outputs, and estimates a received phase of said long code based on said maximum outputs and their detection timings.
Claim 15
Dependent Claim
94 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 12, wherein said phase estimation means obtains a zero-cross point, at which a correlation value between said received signal and said replica of said a priori code becomes zero, from said maximum outputs and their detection timings, and estimates a received phase of said a priori code from said zero-cross point, and said control means controls a generation phase of said replica of said long code in accordance with the estimated received phase of said a priori code.
Claim 16
Dependent Claim
102 words
The acquisition apparatus of the spreading code of the CDMA transmission system as claimed in claim 8, wherein said control means sets the generation phase of said replica of said long code such that the generation phase is centered at the received phase of said a priori code estimated by said phase estimation means, and carries out non-uniform search in which the generation phase of said replica of said long code is gradually shifted in a wider range when a phase of said replica of said long code is not synchronized with a phase of said long code in said received signal.
Claim 17
Dependent Claim
33 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 8, wherein said a priori code is inserted solely at an initial portion of said spreading code.
Claim 18
Dependent Claim
37 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 8, wherein said a priori code is inserted solely at an initial portion of said spreading code of a control channel.
Claim 19
Dependent Claim
26 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 8, wherein said first correlation means is a sliding correlator.
Claim 20
Dependent Claim
111 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 8, wherein said second correlation means comprises an I-correlator and a Q-correlator, said I correlator detecting correlation between an I-component (inphase component) of a carrier of said received signal after quadrature detection and an I-component of said replica of said a priori code, said Q-correlator detecting correlation between a Q component (quadrature component) of the carrier of said received signal after quadrature detection and a Q-component of said replica of said a priori code, and wherein said phase estimation means estimates a received phase of said long code using both said I-component and said Q-component.
Claim 21
Dependent Claim
52 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 18, wherein said phase estimation means obtains a complex amplitude of an output of said I correlator and an output of said Q-correlator, and estimates said received phase of said long code using the complex amplitude.
Claim 22
Dependent Claim
51 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 18, wherein said phase estimation means compares an output of said I-correlator with an output of said Q-correlator, and estimates said received phase of said long code using the output with a greater absolute value.
Claim 23
Dependent Claim
68 words
The acquisition apparatus of the spreading code in the CDMA transmission system as claimed in claim 18, wherein said phase estimation means obtains an estimated received phase of said long code from an output of said I-correlator, and an estimated received phase of said long code from an output of said Q-correlator, and estimates said received phase of said long code by averaging these two estimated received phases.
Claim 24
Dependent Claim
168 words
A receiver in a CDMA system which demodulates desired information by receiving a received signal including a spread signal and an a priori code, said spread signal being spread by a long code which is a spreading code with a period longer than information symbol, said a priori code having a negligibly small cross-correlation with said long code, and representing a phase of said long code, said receiver comprising: first correlation means for generating a replica of said long code, and for calculating a correlation between said received signal and said replica of said long code; second correlation means for generating a replica of said a priori code, and for calculating a correlation between said received signal and said replica of said a priori code; phase estimation means for estimating received phase of said long code based on an output of said second correlation means; and means for controlling a generation phase of said replica of said long code based on an output of said phase estimation means.
Claim 25
Dependent Claim
168 words
A receiver in a CDMA system which demodulates desired information by receiving a received signal including a spread signal and an a priori code, said spread signal being spread by a long code which is a spreading code with a period longer than information symbol, said a priori code having a negligibly small cross-correlation with said long code, and representing a phase of said long code, said receiver comprising: first correlation means for generating a replica of said long code, and for calculating a correlation between said received signal and said replica of said long code; second correlation means for generating a replica of said a priori code, and for calculating a correlation between said received signal and said replica of said a priori code; phase estimation means for estimating received phase of said long code based on an output of said second correlation means; and means for controlling a generation phase of said replica of said long code based on an output of said phase estimation means.
Claim 26
Dependent Claim
207 words
A CDMA transmission system comprising: long code generating means for generating a long code which is a spreading code with a period longer than information symbol; spreading means for generating a wideband spread signal by spreading transmission information using said long code; a priori code generating means for generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; a priori code insertion means for inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; transmission means for transmitting said frames; receiving means for receiving said frames; first correlation means for generating a replica of said long code, and for calculating a correlation between a received signal and said replica of said long code; second correlation means for generating a replica of said a priori code, and for calculating a correlation between said received signal and said replica of said a priori code; phase estimation means for estimating received phase of said long code based on an output of said second correlation means; and means for controlling a generation phase of said replica of said long code based on an output of said phase estimation means.
Claim 27
Dependent Claim
207 words
A CDMA transmission system comprising: long code generating means for generating a long code which is a spreading code with a period longer than information symbol; spreading means for generating a wideband spread signal by spreading transmission information using said long code; a priori code generating means for generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; a priori code insertion means for inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; transmission means for transmitting said frames; receiving means for receiving said frames; first correlation means for generating a replica of said long code, and for calculating a correlation between a received signal and said replica of said long code; second correlation means for generating a replica of said a priori code, and for calculating a correlation between said received signal and said replica of said a priori code; phase estimation means for estimating received phase of said long code based on an output of said second correlation means; and means for controlling a generation phase of said replica of said long code based on an output of said phase estimation means.
Claim 28
Dependent Claim
87 words
A transmission method in a CDMA transmission system comprising the steps of: generating a long code which is a spreading code with a period longer than information symbol; generating a wideband spread signal by spreading transmission information using said long code; generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; and transmitting said frames.
Claim 29
Dependent Claim
87 words
A transmission method in a CDMA transmission system comprising the steps of: generating a long code which is a spreading code with a period longer than information symbol; generating a wideband spread signal by spreading transmission information using said long code; generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; and transmitting said frames.
Claim 30
Dependent Claim
168 words
An acquisition method of a spreading code in a CDMA transmission system which demodulates desired information by receiving a received signal including a spread signal and an a priori code, said spread signal being spread by a long code which is a spreading code with a period longer than information symbol, said a priori code having a negligibly small cross-correlation with said long code, and representing a phase of said long code, said acquisition method comprising the steps of: generating a replica of said long code; calculating a correlation between said received signal and said replica of said long code; generating a replica of said a priori code; calculating a correlation between said received signal and said replica of said a priori code; estimating received phase of said long code based on said correlation between said received signal and said replica of said a priori code; and controlling a generation phase of said replica of said long code based on an estimated received phase of said long code.
Claim 31
Dependent Claim
168 words
An acquisition method of a spreading code in a CDMA transmission system which demodulates desired information by receiving a received signal including a spread signal and an a priori code, said spread signal being spread by a long code which is a spreading code with a period longer than information symbol, said a priori code having a negligibly small cross-correlation with said long code, and representing a phase of said long code, said acquisition method comprising the steps of: generating a replica of said long code; calculating a correlation between said received signal and said replica of said long code; generating a replica of said a priori code; calculating a correlation between said received signal and said replica of said a priori code; estimating received phase of said long code based on said correlation between said received signal and said replica of said a priori code; and controlling a generation phase of said replica of said long code based on an estimated received phase of said long code.
Claim 32
Dependent Claim
174 words
A CDMA transmission method comprising the steps of: generating a long code which is a spreading code with a period longer than information symbol; generating a wideband spread signal by spreading transmission information using said long code; generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; transmitting said frames; receiving said frames; generating a replica of said long code; calculating a correlation between said received signal and said replica of said long code; generating a replica of said a priori code; calculating a correlation between said received signal and said replica of said a priori code; estimating received phase of said long code based on said correlation between said received signal and said replica of said a priori code; and controlling a generation phase of said replica of said long code based on an estimated received phase of said long code.
Claim 33
Dependent Claim
174 words
A CDMA transmission method comprising the steps of: generating a long code which is a spreading code with a period longer than information symbol; generating a wideband spread signal by spreading transmission information using said long code; generating a priori code representing a phase of said long code, a cross-correlation between said a priori code and said long code being negligibly small; inserting said a priori code into said spread signal at a predetermined fixed interval to form frames; transmitting said frames; receiving said frames; generating a replica of said long code; calculating a correlation between said received signal and said replica of said long code; generating a replica of said a priori code; calculating a correlation between said received signal and said replica of said a priori code; estimating received phase of said long code based on said correlation between said received signal and said replica of said a priori code; and controlling a generation phase of said replica of said long code based on an estimated received phase of said long code.
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