Pulse or digital communications – Repeaters – Testing
Reexamination Certificate
1997-03-10
2003-02-11
Le, Amanda T. (Department: 2734)
Pulse or digital communications
Repeaters
Testing
C375S224000, C375S285000, C375S346000, C037S353000, C037S342000, C455S517000, C455S422100, C455S067700, C455S069000
Reexamination Certificate
active
06519278
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transmitting/receiving apparatus for performing transmission and reception by using a plurality of spreading codes and more particularly, to a transmitting/receiving apparatus which can increase and decrease the number of spreading codes in accordance with a grade of link quality.
2. Description of the Related Art
A conventional example of a transmitting/receiving apparatus for performing transmission and reception by using a plurality of spreading codes is shown in block diagram form in FIG.
1
. When the transmitting/receiving apparatus is installed in a base station which can afford to use 20 spreading codes for reverse and forward links, respectively, at a time, it operates as will be described below. Since this base station can use 20 spreading codes at a time, it can accommodate 20 mobile stations using a single spreading code.
Firstly, the operation of a receiver of the transmitting/receiving apparatus will be described. By transferring a switch
202
to a down-converter
204
, a receiving signal
203
received by an antenna
201
is inputted to the down-converter
204
. In the down-converter
204
, a carrier frequency of the receiving signal
203
is down-converted into an IF frequency, so that.the receiving signal
203
is converted into an IF signal
205
. In a quadrature detector
206
, the IF signal
205
from the down-converter
204
is quadrature-detected, so that the IF signal
205
is converted into an in-phase signal (I-ch)
207
and a quadrature signal (Q-ch)
208
. The in-phase signal
207
and quadrature signal
208
are inputted to analog/digital converters (A/D converters)
213
and
214
via low-pass filters (LPF's)
209
and
210
so as to be converted into a digital in-phase signal
215
and a digital quadrature signal
216
, respectively. The LPF's
209
and
210
are used to suppress frequency components in the in-phase and quadrature signals
207
and
208
which are ½ or more of a sampling frequency in the A/D converters
213
nd
214
and to shape waveforms of the in-phase and quadrature signals
207
and
208
. The digital in-phase signal
215
and digital quadrature signal
216
delivered out of the A/D converters
213
and
214
are inputted to 20 demodulating units
217
1
to
217
20
. First to twentieth codes
227
, which are identical to the 20 spreading codes used during transmission, are generated by a reception code generator
226
and inputted one by one to the demodulating units
217
1
to
217
20
. The demodulating unit
217
1
includes despreaders
218
1
and
219
1
for multiplying the first code
227
which is identical to the first one of the 20 spreading codes used during transmission by the digital in-phase signal
215
and the digital quadrature signal
216
, respectively, to reproduce two transmitting symbols
220
1
and
221
1
, a decoder
222
1
for decoding the two reproduced transmitting symbols to a bit signal
223
1
, and a frame decomposer
224
1
for deriving information concerning the kind and the number of the spreading codes from a frame format contained in the bit signal
223
1
and delivering receiving data
225
of the first code. The remaining demodulating units
217
2
to
217
20
are constructed similarly to the demodulating unit
217
1
.
Next, the operation of a transmitter of the transmitting/receiving apparatus will be described. In a frame assembler
229
, transmitting data
228
is arranged in a frame format in accordance with the number of spreading codes used and a data amount of the transmitting data
228
. In a transmission code generator
236
, spreading codes
237
to be used are determined on the basis of information concerning the spreading codes and spreading code information owned by the base station which are sent from each of the demodulating units
217
1
to
217
20
. Transmitting information pieces
230
delivered out of the frame assembler
229
are inputted to 20 modulating units
231
1
to
231
20
. The modulating unit
231
1
has a modulator
232
1
for mapping the transmitting information to an in-phase signal (I-ch)
233
1
and a quadrature signal (Q-ch)
234
1
, and spreaders
235
1
and
235
2
for spread-processing the in-phase signal
233
1
and the quadrature signal
234
1
by using one of the spreading codes
237
. The remaining modulating units
231
2
to
231
20
are constructed similarly to the modulating unit
2311
. Output signals
238
and output signals
239
from the modulating units
231
1
to
231
20
are added by adders
240
and
241
, respectively. Output signals
242
and
243
of the adders
240
and
241
are converted from digital signals to analog signals by means of digital/analog converters (D/A converters)
244
and
245
, respectively. Output signals
246
and
247
of the D/A converters
244
and
245
are inputted to a quadrature modulator
252
via LPF's
248
and
249
, respectively, so that a base-band signal is converted into an IF signal
253
. The LPF's
248
and
249
are adapted to eliminate higher harmonic components in the output signals
246
and
247
of the D/A converters
244
and
245
and to shape waveforms of the output signals
246
and
247
of the D/A converters
244
and
245
. The IF signal is up-converted from the IF frequency to a carrier frequency by means of an up-converter
254
so as to be converted into a transmitting signal
255
. The transmitting signal
255
is inputted to the antenna
201
via the switch
202
and transmitted to the mobile station.
In the aforementioned transmitting/receiving apparatus, however, transmitting data pieces are transmitted while being superimposed on each other by using a plurality of spreading codes and as compared to a transmitting/receiving apparatus adapted to transmit transmitting data by using a single spreading code, the service area is disadvantageously narrowed for the following reasons:
(1) Much transmitting power is required for transmission over the same distance; and
(2) The transmitting distance is reduced when the transmitting power is made to be equal for the both types of apparatuses.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a transmitting/receiving apparatus using a plurality of spreading codes which can expand the service area.
In a transmitting/receiving apparatus using a plurality of spreading codes according to the present invention, quality of a transmitting signal from a mobile station (hereinafter referred to as a reverse link signal) is examined in a base station and when the quality of the reverse link signal is bad, the number of spreading codes to be used is decreased but on the other hand, when the quality of the reverse link signal is good, the number of spreading codes to be used is increased. An upper limit of the number of spreading codes is set to a value prescribed by the system.
In a transmitting/receiving apparatus using a plurality of spreading codes according to the present invention, quality of a transmitting signal from a base station (hereinafter referred to as a forward link signal) is examined in a mobile station and when the quality of the forward link signal is bad, the number of spreading codes to be used is decreased but on the other hand, when the quality of the forward link signal is good, the number of spreading codes to be used is increased. An upper limit of the number of spreading codes is set to a value prescribed by the system.
More specifically, a first transmitting/receiving apparatus using a plurality of spreading codes according to the present invention is represented by transmitting/receiving apparatuses installed in a base station and a mobile station, respectively, to perform mutual transmission and reception by using a plurality of spreading codes,
the transmitting/receiving apparatus installed in the base station comprises means for designating to the mobile station the kind and the number of spreading codes to be used in a reverse link from the mobile station to the base station thr
Matsushita Electric - Industrial Co., Ltd.
Stevens Davis Miller & Mosher L.L.P.
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