EP0854588A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Power control and carrier synchronization in a cellular mobile telephone system
Assignee: NEC Corp
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Filing: 1998-01-15
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Granted: —
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Expires: 2018-01-15
Abstract
Abstract In order to reproduce a highly precise carrier for a coherent detection in a cellular mobile CDMA system, a first stage carrier estimation is performed by using pilot symbols inserted into a received signal and having a known code pattern, a data symbol train of the received signal is preparatively detected by using the estimated carrier and a second stage carrier estimation is performed for the received signal by using the detected data symbol train and the pilot symbols.
Inventors
- 👤 Dobzica Vasic
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 00:43
CPC Classifications
H; H04; H04W; H04W52/00; H04W52/04; H04W52/06; H04W52/08; H04B; H04B7/00; H04B7/24; H04B7/26; H04L; H04L1/00; H04L1/02; H04L1/06; H04L27/00; H04L27/18; H04L27/22; H04L27/233; H04L27/2332; H04W52/38; H04W52/42; H04L27/0014; H04L2027/0044; H04L2027/0046; H04L2027/0083; H04L2027/0089; H04L2027/0093; H04L2027/0095; H04W52/12
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
112 words
A cellular mobile telephone system comprising a cell
device and mobile devices for mutually transmitting and
receiving information signal, said cell device being provided
with channel estimation means for estimating carriers of
received signals from said mobile devices, said channel
estimation means comprising: first estimation means for performing a first stage
carrier estimation from pilot symbols having a known code
pattern and inserted into the received signal; pre-detection means for preparatively detecting a data
symbol train of the received signal by using an estimated
carrier; and second estimation means for performing a second carrier
estimation with respect to the received signal by using the
pre-detected data symbol train and the pilot symbol.
Claim 2
Dependent Claim
38 words
A cellular mobile telephone system as claimed in claim
1, wherein said cell device comprises coherent detection
means for coherently detecting the received signal from said
mobile device by using the carrier estimated by said channel
estimation means.
Claim 3
Dependent Claim
78 words
A cellular mobile telephone system as claimed in claim
1, wherein, in order to regulate a transmission power of said
mobile device, said channel estimation means comprises
calculation means for calculating a ratio Eb/Io of signal
energy to interference power spectrum strength per bit of the
received signal from said mobile device by using the
estimated carrier and means for generating a power adjustment
command corresponding to a deviation of the calculated ratio
from a predetermined ratio Eb/Io.
Claim 4
Dependent Claim
34 words
A cellular mobile telephone system as claimed in claim 3, wherein said mobile device
comprises means responsive to the power adjustment command for regulating a power of a
transmission signal from said mobile device.
Claim 5
Dependent Claim
30 words
A cellular mobile telephone system as claimed in claim 1, wherein the information
signal is transmitted and received by using a code division multiple access (CDMA) spread
spectrum communication signal.
Claim 6
Dependent Claim
70 words
A cellular mobile telephone system as claimed in claim 1, wherein: a plurality of said first estimation means and a plurality of said second estimation
means are provided correspondingly to a plurality of communication paths of a channel;
and said pre-detection means comprises means for compensating for a phase and
amplitude of the received signal and diversity-combining them and means for determining
data symbols from the diversity combined received signal.
Claim 7
Dependent Claim
98 words
A cellular mobile telephone system as claimed in claim 6, wherein said channel
estimation means comprises: means for obtaining estimated values of the ratio of signal power to interference
power of the plurality of said communication paths; means for calculating a ratio of signal to interference of the channel from the
estimated ratio of the signal power to interference power; EbIo calculation means for calculating Eb/Io from the
ratio of signal to interference; and power adjustment command generator means for generating
a control bit for a closed loop power control from the EbIo
from said EbIo calculation means.
Claim 8
Dependent Claim
43 words
A cellular mobile telephone system as claimed in claim
1, wherein said first carrier estimation means estimates a
carrier by interpolating a carrier of a data symbol portion
other than the pilot symbols with the measured channel value
obtained by the pilot symbols.
Claim 9
Dependent Claim
43 words
A cellular mobile telephone system as claimed in claim
1, wherein said pre-detection means comprises hard decision
means for performing a hard decision of the data symbols and
means for multiplexing the data symbols obtained from the
hard decision with known pilot symbols.
Claim 10
Dependent Claim
23 words
A cellular mobile telephone system as claimed in claim
9, wherein said hard decision means detects the data symbols
by a coherent detection.
Claim 11
Dependent Claim
61 words
A cellular mobile telephone system as claimed in claim
1, wherein said second estimation means comprises rotation
means for rotating the samples of a signal, dividing means
for dividing the samples to a plurality of groups,
accumulating and averaging means for accumulating and
averaging the samples of every group and second interpolation
means for interpolating the accumulated and averaged sample
values.
Claim 12
Dependent Claim
40 words
A cellular mobile telephone system as claimed in claim 11, wherein, in order to
remove a modulation, said rotation means multiply the signal sample with a conjugate
value or the pilot symbols to provide a condition of the sample accumulation.
Claim 13
Dependent Claim
41 words
A cellular mobile telephone system as claimed in claim 11, wherein said dividing
means divides the rotated signal samples from said rotation means to approximate the
signals in the respective groups to quasi static signals in periods of the respective groups.
Claim 14
Dependent Claim
49 words
A cellular mobile telephone system as claimed in claim 11, wherein said accumulating
and averaging means calculates the estimated carrier values of the respective groups by
using the accumulation and averaging of the samples to reduce an influence of
accompanying noise and interference to thereby improve the estimation performance.
Claim 15
Dependent Claim
52 words
A cellular mobile telephone system as claimed in claim 11, wherein said second
interpolation means interpolates the estimated carrier values given by said accumulating
and averaging means, to obtain an estimated value of the carrier signal for compensation for
fading distortion, diversity-reception, multiplication for synthesis with maximum ratio and actual coherent detection.
Claim 16
Dependent Claim
57 words
A cellular mobile telephone system as claimed in claim 11, further comprising signal
power estimation means for estimating a signal power by using an output of said second
interpolation means and interference power estimation means for estimating an interference
power by using an output of said sample rotation means and the output of said second
interpolation means.
Claim 17
Dependent Claim
64 words
A cellular mobile telephone system as claimed in claim 16, further comprising: EbIo calculation means for calculating a whole Eb/Io by using the signal powers and
the interference powers estimated for the plurality of the communication paths; and power adjustment command generator means for generating a control bit for a closed
loop power control by using the Eb/Io obtained by said EbIo calculation means.
References Cited (Backward Citations)
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