JP2001177486A - Band assignment device, transmission system and band assignment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress leakage power to adjacent channels in the case of simultaneously transmitting modulation signals with a plurality of bandwidths. SOLUTION: In the case of assigning bands to a plurality of modulation signals 41-44, when a minimum interval Δf0 between the bands assigned to the modulation signals is decided, the bands are assigned so that the interval between the assigned bands is the minimum interval. When the bands that can be assigned to the modulation signals are decided in advance in the case of assigning the bands to a plurality of the modulation signals, the bands are assigned to the modulation signals so that the interval between the assigned bands is as small as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band allocating apparatus and method for suppressing adjacent channel leakage power when transmitting modulated signals of a plurality of bandwidths at the same time, and a transmission system provided with the apparatus. INDUSTRIAL APPLICABILITY The present invention is applicable to wireless communication represented by mobile communication, wired communication transmitting CATV, and the like.

[0002]

2. Description of the Related Art Conventionally, when simultaneously transmitting modulation signals of a plurality of systems (bandwidths), the frequency allocation (bandwidth allocation) of narrowband modulation signals is not particularly considered, or even if it is considered,
In many cases, frequency arrangements in which the influence of distortion is reduced within the system are often studied. Regarding the influence on other systems with different (occupied) bandwidths, the worst value (composite) of distortion due to the entire wave number and the like has been studied, but this is only an evaluation based on CW (Continuous Wave: unmodulated wave). No consideration has been given to the transmission of waves and the adjacent channel leakage power.

[0003]

An examination will be made on the basis of the influence of distortion when a modulated signal is actually transmitted. When transmitting a modulated signal of a mobile communication system and there are signals of a plurality of systems,
The number of waves to be transmitted increases, and the influence of distortion increases. By preventing the triple beat generated between signals of different systems from leaking out of the band of the transmitted signal, it is possible to minimize the influence of the leakage power of the adjacent channel of the system having a modulation signal with a wide occupied bandwidth. . This makes it possible to maintain good communication quality in a wideband signal system, and to increase the number of waves transmitting a narrowband signal.

[0004] When there are N narrowband (modulation) signals and one wideband (modulation) signal, the total power of the triple beats of any two of the N narrowband signals and one wideband signal. TB [dBm] is 3 by two narrowband signals.
_Assuming that the next intermodulation distortion is IM _800M and that the levels of two narrow-band signals and one wide-band signal are the same, the following equation is obtained.

[0005]

(Equation 1)

[0006] A part of the power leaks out of the band, which causes deterioration of adjacent channel leak power. The leakage power is expressed by the following equation using the frequency interval (inter-band interval) Δf of the narrowband signal.

[0007]

(Equation 2)

Here, P _ds is a triple beat noise power density generated by two unmodulated waves (narrow band) and one wide band modulated wave.

FIG. 1 shows an example in which four narrowband signals 11 to 14 and one wideband signal 21 are present.
Narrow band signal 11 and narrow band signal 12, narrow band signal 12 and narrow band signal 13, and narrow band signal 12 and narrow band signal 13
Are Δf.

FIG. 2 shows the four narrow band signals 11 shown in FIG.
14 is a diagram illustrating a relationship between the wideband signal 21 and the triple beat and adjacent channel leakage power when the signals are combined and transmitted at the same time. FIG. A triple beat when the frequency interval Δf of the narrow band signal is small is a triple beat 31, and a triple beat when the frequency interval Δf is large is a triple beat 32. The hatched portion indicates the adjacent channel leakage power in the triple beat 32. From this, it can be seen that as Δf increases, the adjacent channel leakage power increases.

From the above, it can be seen that the narrower (smaller) frequency interval Δf of the narrowband signal can suppress the adjacent channel leakage power. If the adjacent channel leakage power can be suppressed, the wave number of the narrowband signal can be increased.

The frequency adjacent to the wideband signal may be used by another carrier, and it is desired to reduce unnecessary leakage power as much as possible. On the other hand, in order to realize the device at as low a price as possible, it is necessary to suppress the degree of improvement in distortion performance as much as possible. According to the present invention, even when the number of signals to be newly transmitted is increased, it is possible to reduce the apparatus price as much as possible.

FIG. 3 is a diagram showing an example in which bands are allocated to four narrow band signals 41 to 44. When the minimum interval (minimum frequency interval) Δf ₀ between the bands to be allocated to the narrowband signal is determined, it is preferable to allocate the band as shown in FIG. 3B, and allocate the band as shown in FIG. It is not preferable. Where Δf ₁ , Δf ₂ and Δf
₃ is larger than Δf ₀ .

FIG. 4 is a diagram showing an example in which bands are allocated to four narrowband signals when bands 51 to 58 that can be allocated to the modulation signal are predetermined. In FIG. 4A, the bands 51, 5 are assigned to the four modulated signals.
3, 56 and 58 are allocated, and in FIG. 4B, bands 51, 52, 53 and 54 are allocated to four modulation signals. In this case, it is preferable to allocate a band as shown in FIG. 4B, and it is not preferable to allocate a band as shown in FIG. That is, as shown in FIG.
It is preferable to assign so that the interval between assigned bands is as small as possible.

An object of the present invention is to suppress adjacent channel leakage power when simultaneously transmitting modulated signals of a plurality of bandwidths.

[0016]

In order to achieve the above object, an invention according to claim 1 is a band allocation device,
When assigning a band to a plurality of modulation signals, if a minimum interval between bands to be assigned to the modulation signal is determined,
Bands are allocated so that an interval between bands to be allocated becomes the minimum interval.

According to a second aspect of the present invention, there is provided a band allocating apparatus, wherein when allocating a band to a plurality of modulation signals, a band that can be allocated to the modulation signal is determined in advance. It is characterized in that the assignment is made such that the interval between them is as small as possible.

According to a third aspect of the present invention, there is provided a band allocating apparatus, comprising a plurality of the band allocating apparatuses according to the first or second aspect, wherein the band allocating apparatus synthesizes a modulated signal to which a band is allocated. Is further provided.

According to a fourth aspect of the present invention, there is provided a transmission system, wherein the bandwidth allocating apparatus according to the first or second aspect, another bandwidth allocating apparatus for allocating a bandwidth to a modulated signal, and the first or second aspect. 3. A band allocating apparatus according to claim 1, further comprising: a synthesizing apparatus for synthesizing a modulated signal to which a band is allocated by the band allocating apparatus according to claim 1 and a modulated signal to which a band is allocated by the other band allocating apparatus. Is narrower than the bandwidth allocated by the other band allocation device.

According to a fifth aspect of the present invention, there is provided a band allocating method, wherein when allocating a band to a plurality of modulated signals, a minimum interval between bands to be allocated to the modulated signals is determined. Bands are allocated so that an interval between them becomes the minimum interval.

According to a sixth aspect of the present invention, there is provided a band allocating method, wherein when allocating a band to a plurality of modulation signals, if a band that can be allocated to the modulation signal is predetermined, the band to be allocated is determined. It is characterized in that the assignment is made such that the interval between them is as small as possible.

According to the configuration described above, adjacent channel leakage power can be suppressed when transmitting modulated signals of a plurality of bandwidths simultaneously.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 5 is a diagram showing a configuration example of a transmission system according to the embodiment of the present invention. The transmission system shown in FIG. 5 is a system for providing a mobile communication service to a place in a building where radio waves are difficult to reach. The transmission system shown in FIG.
1, photoelectric conversion devices 131 to 133, optical fiber 141,
And antennas 151 and 152.

The band allocating devices 111 to 113
A band is allocated to a modulated signal exchanged between the control signals 61 and 162. The band allocation devices 111 to 113 can take the form of base stations, and provide different services. In the present embodiment, the bandwidth allocating devices 111 and 112
Are PDs of 800MHz band and 1.5GHz band respectively
A narrow band (for example, a bandwidth of 20 kHz
z), and the band allocating device 113 allocates a wide band (for example, 5 MHz bandwidth) to a 2 GHz band modulated signal (for example, a modulated signal used in IMT-2000).

From the band allocating apparatuses 111 to 113, the mobile station 1
Each modulated signal directed to 61, 162 is
1 and are converted by the photoelectric conversion device 131 from an electric signal to an optical signal. The optical signal reaches the photoelectric conversion devices 132 and 133 through the optical fiber 141, is converted into an electric signal again, and is transmitted to the mobile devices 161 and 162 through the antenna. From the mobile units 161 and 162, the band allocation device 1
For the modulated signals directed to 11 to 113, the reverse of the above processing is performed.

When allocating a band to a plurality of modulation signals, the band allocating devices 111 to 113 set the interval between bands to be allocated to the minimum interval if the minimum interval between bands to be allocated to the modulation signal is determined. Allocate bandwidth so that Generally, the minimum interval between bands allocated to the modulation signal is determined in consideration of adjacent channel leakage power, selectivity of a receiver, and the like. The minimum interval between the bands allocated to the PDC signal is, for example, 50 kHz or 100 kHz.
z can be considered.

When allocating a band to a plurality of modulation signals, the band allocating devices 111 to 113 can set an interval between bands to be allocated if a band that can be allocated to the modulation signal is predetermined. Assign as small as possible.

From the viewpoint of suppressing the adjacent channel leakage power of the wideband signal due to the narrowband signal, the band allocating device 113 that allocates a wide band may be a conventional band allocating device.

[0030]

As described above, according to the present invention, it is possible to suppress adjacent channel leakage power when simultaneously transmitting modulated signals of a plurality of bandwidths.

[Brief description of the drawings]

FIG. 1 is an example where four narrowband signals and one wideband signal are present.

FIG. 2 is a diagram showing a relationship between a wideband signal, triple beats, and adjacent channel leakage power when four narrowband signals and a wideband signal shown in FIG. 1 are combined and simultaneously transmitted.

FIG. 3 is a diagram illustrating an example of allocating bands to four narrowband signals.

FIG. 4 is a diagram illustrating an example in which bands are allocated to four narrowband signals when bands that can be allocated to modulated signals are predetermined.

FIG. 5 is a diagram illustrating a configuration example of a transmission system according to an embodiment of the present invention.

[Explanation of symbols]

 11 to 14, 41 to 44 Narrow band signal 21 Wide band signal 31, 32 Triple beat 51 to 58 Band 111 to 113 Band allocation device 121 Synthesizing device 131 Photoelectric conversion device 141 Optical fiber 151, 152 Antenna 161, 162 Mobile device

Claims (6)

[Claims] When allocating a band to a plurality of modulation signals, if a minimum interval between bands to be allocated to the modulation signal is determined, the band is allocated so that an interval between bands to be allocated becomes the minimum interval. A bandwidth allocating apparatus characterized by the above-mentioned. 2. When allocating a band to a plurality of modulation signals, if a band that can be allocated to the modulation signal is predetermined, it is preferable to allocate the band so that the interval between the allocated bands is as small as possible. Characteristic band allocation device. 3. A transmission system comprising a plurality of the band allocating devices according to claim 1 or 2, further comprising a synthesizing device for synthesizing a modulated signal to which a band is allocated by the band allocating device. 4. A band allocating device according to claim 1 or 2, another band allocating device that allocates a band to a modulated signal, and a modulated signal having a band allocated by the band allocating device according to claim 1 or 2. And a synthesizing device for synthesizing a modulated signal to which a band has been allocated by the other band allocating device, wherein a bandwidth allocated by the band allocating device according to claim 1 or 2 is determined by the other band allocating device. A transmission system characterized by being narrower than an allocated bandwidth. 5. When assigning a band to a plurality of modulation signals, if a minimum interval between bands to be assigned to the modulation signal is determined, the band is assigned so that the interval between the bands to be assigned is the minimum interval. A bandwidth allocation method characterized by the above-mentioned. 6. When allocating a band to a plurality of modulation signals, if a band that can be allocated to the modulation signal is determined in advance, the band is allocated so that the interval between the allocated bands is as small as possible. Characteristic band allocation method.