EP0838910A2
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EP
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Acquisition scheme and receiver for an asynchronous DS-CDMA cellular communication system
Assignee: NTT Docomo Inc
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Filing: 1997-10-22
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Granted: —
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Expires: 2017-10-22
Abstract
Abstract The present invention realizes a rapid and efficient cell search and small-size instrument for an asynchronous DS-CDMA cellular system. This cell search detects the correlation between the received signal and the short code of the control channel, and matched filter 22 detects the maximum electric power correlation peak location. Next, using correlators 28-1 to 28-n which are parallelly set in a plurality for RAKE processing with plurality, identifies the long code that is set in the system with the detected long code timing. After the long code is synchronized, a multipath signal is received using 28-1 to 28-n, and the data is judged by RAKE processing. When peripheral cell search is executed, after long code timing is detected by using matched filter 22, the long code of the candidate peripheral cell is designated using the same matched filter. Handover is safely realized by receiving the signal from the connected base station by correlators 28-1 to 28-n, and the base station signal through handover by 22.
Inventors
- 👤 Guoliang Shou
- 👤 Changming Zhou
- 👤 Xuping Zhou
- 👤 Makoto Yamamoto
- 👤 Sunao Takatori
- 👤 Mamoru Sawahashi
- 👤 Fumiyuki Adachi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 18:49
CPC Classifications
H; H04; H04W; H04W48/00; H04W48/18; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7073; H04B1/7083; H04B1/70735; H04B1/7075; H04B1/7077; H04B1/70775; H04B1/708; H04B1/709; H04B1/7093; H04B1/7097; H04B1/711; H04B1/7115; H04B1/7117; H04B2201/00; H04B2201/69; H04B2201/707; H04B2201/70702; H04W36/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
259 words
An acquisition scheme for an asynchronous DS-CDMA cellular
communication system, using spread code sequences having a long code
peculiar to each cell and a short code corresponding to each
communication channel, and a control channel among said communication
channels employing a specified short code common to each cell, with (a) two steps for accomplishing the initial cell search: (1) detecting a correlation between said specified short
code and a received signal, and detecting a long code
timing of a relevant base station according to the
maximal value of correlated outputs, and (2) identifying a long code of said base station through
parallel detection of said long code used in the
relevant system, by using a plurality of parallel
correlators, or using both said plurality of correlators
and a matched filter according to said detected long
code timing; and (b) two steps for accomplishing a peripheral cell search: (1) detecting a correlation between said specified short
code and received signal, and detecting a long code
timing of a relevant base station according to
correlated outputs, and (2) identifying said long code of said base station through
handover by sequentially detecting a correlation with
a long code corresponding to a peripheral cell using
said matched filter while communication is continued
with the present cell by employing said plurality of
parallel correlators according to said detected long
code timing, or by sequentially detecting a correlation
with a long code corresponding to a peripheral cell
using said plurality of correlators while
communication is continued with the present cell by
employing said matched filter.
Claim 2
Dependent Claim
196 words
A receiver for an asynchronous DS-CDMA cellular
communication system using spread code sequences having a long code
peculiar to each cell and a short code corresponding to each
communication channel, and employing a specified short code common to
each cell in the receiver's control channel, comprising: i) a matched filter for detecting a correlation between a
received signal and a spread code sequence; ii) a plurality of correlators parallelly set for detecting a
correlation between said received signal and spread code
sequence; iii) a long code timing detector for detecting the maximal
correlated output of said matched filter; iv) a long code synchronization judging means for
receiving said correlated output from said matched
filter; v) a long code synchronization judging means for receiving
said correlated output from said plurality of correlators; vi) a correlator controller for receiving an output of said
long code timing detector and for controlling the action
of said plurality of correlators; and vii) a spread code controller for receiving an
output from said long code synchronization judging
means, and for outputting control signals to select a
spread code sequence used for correlating action in said
matched filter and said plurality of correlators.
Claim 3
Dependent Claim
76 words
A receiver for the asynchronous DS-CDMA cellular
communication system as claimed in claim 2, wherein said plurality of
correlators further comprises a delay-locked loop for performing
acquisition of a received spread spectrum signal, said correlator controller
controls the action of said plurality of correlators according to the peak
location of the correlated output from said matched filter, and the data
output from said plurality of correlators and from said matched filter are
judged through RAKE processing.
Claim 4
Dependent Claim
43 words
A receiver for the asynchronous DS-CDMA cellular
communication system as claimed in claim 2, wherein after long code
synchronization, a traffic channel signal is received using said matched
filter and said plurality of correlators, and multipath signal data are
judged after RAKE processing.
Claim 5
Dependent Claim
110 words
A receiver for the asynchronous DS-CDMA cellular
communication system as claimed in claim 3 or 4, wherein after long code
synchronization, a traffic channel signal from the base station of the
present cell is received using said matched filter and some correlators
among said plurality of correlators, RAKE processing is performed, a
control channel signal from the base station of a peripheral cell is received
using the remaining correlators, the long code of said cell is recognized
and synchronized, a data signal the same as that from the base station of
the present cell is received, and signals from both base stations or a
plurality of base stations are judged.
Claim 6
Dependent Claim
83 words
A receiver for the asynchronous DS-CDMA cellular
communication system as claimed in one of claims 3 to 5, wherein a
multipath signal contained in said matched filter undergoes RAKE
processing to communicate with the base station of the present cell using
said matched filter, and a long code is divided into the length of a short
code to detect the long code corresponding to said present cell or said
peripheral cell by said matched filter, and correlations are sequentially
detected by every symbol.
Claim 7
Dependent Claim
117 words
A receiver for the asynchronous DS-CDMA cellular
communication system as claimed in one of claims 2 to 6, wherein said
matched filter comprises a plurality of multiplication circuits for
outputting the output of a plurality of sampling and holding circuits to the
first and second output terminals according to the bit value corresponding
to the spread code sequence, a first analog addition circuit for adding the
output of the first output terminal of each said multiplication circuit, a
second analog addition circuit for adding the output of the second output
terminal of each said multiplication circuit, and a third analog addition
circuit for calculating the difference between the outputs of said first and
second analog addition circuits.
References Cited (Backward Citations)
No citation records indexed.
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