Telecommunications – Transmitter – Plural separate transmitters or channels
Reexamination Certificate
2000-03-16
2002-07-09
Chin, Vivian (Department: 2682)
Telecommunications
Transmitter
Plural separate transmitters or channels
Reexamination Certificate
active
06418302
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a wireless device that performs transmission of multiple wireless channels arranged within the used frequency band at prescribed frequency intervals.
In a wireless communication system, sometimes a single frequency is used, and sometimes multiple frequencies are used, and in a mobile communication system, in order to make efficient use of the used frequency band, multiple wireless channels are arranged at fixed frequency intervals and wireless devices are used that allow transmission and reception of multiple wireless channels. This invention concerns a wireless device that makes it possible to transmit such multiple wireless channels efficiently.
BACKGROUND OF THE INVENTION
In a wireless communication system such as a mobile communication system, a high-frequency band of several GHz or more is used to make high-speed wireless transmission possible and increase the number of terminals that can be accommodated within the wireless frequency-band. In order to make efficient use of the wireless frequency band, the frequency spacing is made as narrow as possible, and a composition is used in which the wireless channels are arranged continuously.
The transmission amplifier for amplifying the transmitted signal performs high-efficiency amplification by carrying out the amplification operation near the saturated output. But because of the nonlinearity near the saturated output, the amplified output signal contains a distortion component, which leaks into neighboring channels. Thus, various distortion-compensating amplifiers have been proposed that suppress this distortion component.
FIG. 5
is a diagram for explaining a distortion-compensating amplifier;
51
is a distributor,
52
is a vector adjuster,
53
is a main amplifier,
54
is a delay line,
55
is directional coupler,
56
is a delay line,
57
is a composer,
58
is a vector adjuster, and
59
is an auxiliary amplifier.
The input signal is divided into two by distributor
51
; one part is input via vector adjuster
52
to main amplifier
53
, whose amplified output signal is input to directional coupler
55
, and the other part of the input signal that is divided into two by distributor
51
is input via delay line
54
to directional coupler
55
. Delay line
54
is for correcting the delay time between vector adjuster
52
and main amplifier
53
.
Accordingly, the amplified output signal from main amplifier
53
and the delayed input signal that goes through delay line
54
go through directional coupler
55
and are combined and output in a prescribed ratio to delay line
56
and vector adjuster
58
. The distortion component due to main amplifier
53
consists of the difference between the amplified output signal and the input signal, so this difference is amplified by auxiliary amplifier
59
and is composed and output by composer
57
so as to cancel the distortion component of the amplified output signal of main amplifier
53
. In this way it is possible to amplify the input signal while operating main amplifier
53
near its saturation output and to produce an output signal in which the distortion component of the amplified output signal is corrected.
A common amplification system, in which the transmission signals of multiple wireless channels are amplified in common, and an individual amplification system, in which the transmission signal is amplified in correspondence with a wireless channel, are well known.
FIG. 6
is a diagram for explaining the common amplification system of a conventional example. In this diagram,
61
-
1
through
61
-n are modulators that correspond to wireless channels,
62
is a composer,
63
is a transmission amplifier,
64
is a transmission-reception signal splitter,
65
is an antenna, and
66
is a receiver.
The modulated output signals of modulators
61
-
1
through
61
-n corresponding to the wireless channels are composed by composer
62
and input to transmission amplifier
63
. This transmission amplifier
63
employs, for example, a composition of the aforesaid distortion-compensating amplifiers, amplifies the output signals of the wireless channels in common, and transmits it from antenna
65
via transmission-reception signal splitter
64
.
FIG. 7
is a diagram for explaining the individual amplification system of a conventional example;
71
-
1
through
71
-n are modulators that correspond to wireless channels,
72
-
1
through
72
-n are transmission amplifiers corresponding to the wireless channels,
73
-
1
through
73
-n and
74
-
1
through
74
-n are band elimination filters,
75
is a composer,
76
is a transmission-reception signal splitter,
77
is an antenna, and
78
is a receiver.
The transmitted signals corresponding to the wireless channels are modulated by modulators
71
-
1
through
71
-n and are each amplified by its corresponding transmission amplifier
72
-
1
through
72
-n. In this case, the adjacent channel leakage power is eliminated by band elimination filters
73
-
1
through
73
-n and
74
-
1
through
74
-n, they are composed by composer
75
, and the composed signal is transmitted from antenna
77
via transmission-reception signal splitter
76
.
FIG. 8
is an explanatory diagram of the arrangement of wireless channels; for example, it shows the spectra of wireless channels CH
1
through CH
4
, each of which includes relatively large leakage power into the adjacent channels. Thus a filter having steep attenuation characteristics is proposed. For example, by connecting band elimination filters
91
and
92
having the frequency response shown in
FIG. 9
, it is possible to have as the transmission signal only the band that is exclusively occupied by a given wireless channel.
As filters for eliminating unwanted waves, superconducting filters are known. For example, by composing a band-pass filter by connecting resonators that are cooled to a superconducting state in multiple cascades, and reducing the resistance to zero, the pass loss of the pass band can be set to zero. In this case, it is known that one can compose a band-pass filter whose unloaded Q is 200,000 and obtain a frequency response of 2 GHz +/−5 MHz (for example, see unexamined patent H9-261082 [1997]).
The individual amplification system of the conventional example requires transmission amplifiers
72
-
1
through
72
-n corresponding to the wireless channels, and presents the problem that its wireless device is of a large size. And for each transmission amplifier
72
-
1
through
72
-n, two band elimination filters having characteristics as shown in
FIG. 9
are required.
In the common amplification system of the conventional example, the transmission signals corresponding to the wireless channels are amplified in common, and its spectrum is as shown in, for example, FIG.
8
. Therefore leakage power into the adjacent channels occurs, and it is nearly impossible to allow only the transmission signal of each wireless channel to pass through with a band-pass filter by a superconducting filter having the aforesaid steep frequency response. That is, it is difficult to narrow the frequency spacing between wireless channels, and with the common amplification system it is no longer possible to make effective use of the wireless frequency band.
Therefore if the wireless channel frequency spacing is broad, it is possible to apply the common amplification system, but if the frequency spacing is made narrow, it is difficult to apply the common amplification system. From such considerations, if the individual amplification system is applied, as mentioned above, this requires transmission amplifiers
72
-
1
through
72
-n and band elimination filters
73
-
1
through
73
-n and
74
-
1
through
74
-n corresponding to the wireless channels, which increases the size and power consumption of the device.
The purpose of this invention is to make it possible to have a smaller-size device with lower power consumption.
SUMMARY OF THE INVENTION
The wireless device of this invention performs transmission of multiple wireless chan
Chin Vivian
Katten Muchin Zavis & Rosenman
Lee John J
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