Pulse or digital communications – Spread spectrum – Direct sequence
Reexamination Certificate
2000-10-30
2002-08-27
Ghayour, Mohammad H. (Department: 2634)
Pulse or digital communications
Spread spectrum
Direct sequence
C375S295000, C375S296000
Reexamination Certificate
active
06442192
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a CDMA (code division multiple access) type multiple transmission apparatus and a CDMA type multiple transmission method in which an electric power of a transmission signal is controlled when pieces of transmission data of a plurality of channels are multiplexed with each other and are transmitted as the transmission signal.
2. Description of Related Art
FIG. 1
is a constitutional diagram of a conventional CDMA type multiple transmission apparatus. In
FIG. 1
,
1
indicates a channel section in which transmission data of a channel CH
1
is multiplied by a spread code,
2
indicates a channel section in which transmission data of a channel CH
2
is multiplied by a spread code,
3
indicates a channel section in which transmission data of a channel CH-N (N=3, 4, - - -) is multiplied by a spread code,
4
indicates a spread code generating unit for generating the spread code peculiar to the corresponding channel, and
5
indicates a mixer for multiplying the transmission data by the corresponding spread code.
Each of
6
to
8
indicates an electric power control unit for controlling an amplitude of the corresponding transmission data spread-modulated in the corresponding channel section
1
,
2
or
3
and setting an electric power of the corresponding transmission data,
9
indicates a multiplexing unit for adding the pieces of transmission data output from the electric power control units
6
to
8
to each other to multiplex the pieces of transmission data with each other and outputting a base band signal (an isophase (I) component and a quadrature (Q) component),
10
indicates a digital-to-analog (D/A) converting unit for converting a digital signal, which indicates the base band signal output from the multiplexing unit
9
, to an analog signal indicating the base band signal,
11
indicates a carrier wave generating unit for generating a carrier wave, and
12
indicates an orthogonal modulating unit for orthogonally modulating the base band signal, which is converted to the analog signal in the D/A converting unit
10
, with the carrier wave generated in the carrier wave generating unit
11
and outputting a transmission signal.
13
indicates a variable attenuator for correcting the electric power of the transmission signal output from the orthogonal modulating unit
12
according to a correction signal output from a D/A converting unit
21
,
14
indicates a radio transmitter for modulating the transmission signal, of which the electric power is corrected in the variable attenuator
13
, to a transmission signal of a radio frequency band,
15
indicates a distributor for distributing the transmission signal output from the radio transmitter
14
, and
16
indicates an antenna for radiating the transmission signal distributed in the distributor
15
.
17
indicates a diode for detecting the electric power of the transmission signal distributed in the distributor
15
and outputting a detection signal indicating the electric power of the transmission signal,
18
indicates an analog-to-digital (A/D) converting unit for converting an analog signal indicating the detection signal to a digital signal indicating the detection signal,
19
indicates a data storing unit for storing an electric power table indicating the relationship between a summed value of the electric powers of the pieces of transmission data output from the electric power control units
6
to
8
and the electric power of the transmission signal to be output from the radio transmitter
14
,
20
indicates an electric power correcting unit for measuring values of the electric powers of the pieces of transmission data output from the electric power control units
6
to
8
and outputting the correction signal according to the measured result and the detection signal, and
21
indicates the D/A converting unit for converting a digital signal, which indicates the correction signal output from the electric power correcting unit
20
to an analog signal indicating the correction signal.
Next, an operation is described.
To spread pieces of transmission data of the channels CH
1
to CH-N so as to produce transmission data of a wide frequency band for each channel, in each of the channel sections
1
to
3
corresponding to the channels CH
1
to CH-N, the transmission data of a corresponding channel is multiplied by a spread code peculiar to the corresponding channel, and the pieces of transmission data of the channels CH
1
to CH-N are respectively spread-modulated.
After the pieces of transmission data of the channels CH
1
to CH-N are respectively spread-modulated in the channel sections
1
to
3
, amplitudes of the pieces of transmission data of the channels CH
1
to CH-N are respectively controlled in the electric power control units
6
to
8
to set electric powers of the pieces of transmission data of the channels CH
1
to CH-N to prescribed electric power values set in advance.
After the amplitudes of the pieces of transmission data of the channels CH
1
to CH-N are controlled in the electric power control units
6
to
8
, the pieces of transmission data of the channels CH
1
to CH-N output from the electric power control units
6
to
8
are added to each other in the multiplexing unit
9
to be multiplexed with each other, and a base band signal composed of an I component and a Q component is output.
After a digital signal indicating the base band signal is converted to an analog signal indicating the base band signal in the D/A converting unit
10
, the analog base band signal is orthogonally modulated in the orthogonal modulating unit
12
by using a carrier wave generated in the carrier wave generating unit
11
, and a transmission signal is output.
After the transmission signal is output from the orthogonal modulating unit
12
, the electric power of the transmission signal is corrected in the variable attenuator
13
according to a correction signal output from the D/A converting unit
21
.
More precisely, though the electric powers of the pieces of transmission data are set in the electric power control units
6
to
8
, because there is a case where an electric power of the transmission signal radiated from the antenna
16
deviates from a desired value for electric power (in cases where the electric power of the transmission signal deviates from a desired value for electric power, a channel corresponding to the transmission data of a high electric power may interfere with a channel corresponding to the transmission data of a low electric power), the electric power of the transmission signal is corrected in the variable attenuator
13
according to the correction signal.
For example, in cases where the correction signal indicates the heightening of the electric power of the transmission signal, the electric power of the transmission signal is corrected to heighten the electric power of the transmission signal. In contrast, in cases where the correction signal indicates the lowering of the electric power of the transmission signal, the electric power of the transmission signal is corrected to lower the electric power of the transmission signal. A method of producing the correction signal is described later.
After the electric power of the transmission signal is corrected in the variable attenuator
13
, the transmission signal is modulated to a transmission signal of a radio frequency band in the radio transmitter
14
, and the transmission signal is radio-transmitted through the antenna
16
.
Therefore, the transmission signal is radio-transmitted. However, in cases where the electric power of the transmission signal deviates from a desired value for electric power, to set the electric power of the transmission signal to the desired electric power value, the electric power of the transmission signal distributed in the distributor
15
is detected in the diode
17
, and a detection signal indicating the electric power of the transmission signal is output.
Thereafter, when the pieces of transmission data a
Ghayour Mohammad H.
Rothwell Figg Ernst & Manbeck
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