JP2003110491A - Radio transmission system, its radio transmitter, and reception monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive a desirable signal in high quality by suppressing an interference signal effectively, even in a boundary region among a plurality of service areas. SOLUTION: A radio transmitter BS1 is provided with carrier generators 5a and 5b equipped with frequency offsetting functions. Then, these carrier generators 5a and 5b mutually shift the center frequency (f) of each radio frequency signal to be transmitted to first and second service areas SA and SB by the amount of frequency Δf corresponding to the modulation velocity (bow rate) of transmission information, and transmit each frequency signal where the center frequency is shifted to the above first and second service areas SA and SB using the polarized waves orthogonal to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless transmission system such as a mobile communication system and a broadcasting system, and a wireless transmission device and a monitor receiving device thereof.

[0002]

2. Description of the Related Art In recent years, mobile communication systems such as digital mobile phone systems and digital cordless communication systems have become widespread. In addition, a mobile satellite broadcasting system that broadcasts for mobiles using broadcasting satellites or communication satellites is also planned. Generally, in these systems, a radio signal is transmitted from a base station or satellite provided on the ground to one predetermined service area.

On the other hand, recently, using this kind of system,
It is planned to transmit different information from a single base station or satellite to multiple service areas.
As a multiplexing method, a code division multiplex (CDM) method using the same frequency band is adopted. This type of system has an advantage that a plurality of different service areas can be covered easily and inexpensively without adding a base station or satellite and securing another frequency band.

[0004]

However, since the CDM method using the same frequency band is adopted, the wireless receiving device existing in the boundary area of a plurality of service areas is
It receives interference of radio signals (interference signals) for other adjacent service areas. In order to reduce the deterioration of reception quality due to this interference, a method has been proposed in which, for example, a transmission antenna pattern is formed to provide a power difference between transmission signals for each service area. However, the reception power level of the wireless signal in the wireless reception device is likely to fluctuate and is not constant due to the movement state of the reception device and the influence of the environment. For this reason,
A radio signal desired to be received (desired signal) cannot be stably discriminated from an interference signal, and a sufficient interference suppression effect cannot be obtained.

The present invention has been made in view of the above circumstances, and an object thereof is to effectively suppress an interference signal and receive a desired signal with high quality even in a boundary area of a plurality of service areas. An object of the present invention is to provide a wireless transmission system, a wireless transmission device and a monitor receiving device for the wireless transmission system.

[0006]

In order to achieve the above object, a first invention uses a same frequency band for a radio signal obtained by code division multiplexing different information for a plurality of service areas adjacent to each other. A frequency offset means is newly provided in the wireless transmission device for transmitting each of them. Then, the frequency offset means mutually shifts the center frequency of each radio signal transmitted to the plurality of service areas by a frequency corresponding to an integer multiple of the modulation rate of the information transmitted by the radio signal, Each of the frequency-shifted radio signals is transmitted to each of the plurality of service areas.

Therefore, according to the present invention, even if the radio receiving apparatus receives a radio signal for a desired service area (desired signal) and a radio signal for another service area (interference signal), the reception frequency is set to the above. When the desired signal is tuned to the center frequency of the desired signal, the desired signal is normally demodulated, but the frequency of the demodulation component of the interference signal becomes a value different from the frequency of the demodulation component of the desired signal. For this reason,
The demodulation component of the interference signal can be easily removed by using a filter, which makes it possible to suppress the interference signal component and receive the desired signal with high quality. Moreover, since the shift width of the center frequency is set to an integral multiple of the modulation rate of the transmission information, when the demodulation component of the interference signal is removed by the filter, the demodulation component of the desired signal is not affected effectively. Can be removed.

Further, the present invention is characterized in that polarized waves orthogonal to each other are used when transmitting each radio signal whose center frequency is shifted by the frequency offset means to each of the plurality of service areas. With such a configuration, the reception level of the interference signal can be suppressed to some extent in the high frequency reception stage of the radio signal, and the interference signal component can be suppressed more reliably in combination with the filter processing of the latter stage described above. It becomes possible to do.

A second aspect of the present invention is a radio transmitting apparatus for transmitting radio signals obtained by code division multiplexing different information to a plurality of service areas adjacent to each other using the same frequency band. Spreading modulation means for modulating each piece of information to be transmitted to the service area by using spreading codes orthogonal to each other is provided, and each radio signal obtained by this spreading modulation means is transmitted to each of the plurality of service areas. It was done.

Therefore, according to the present invention, each radio signal transmitted to a plurality of service areas is a signal in which orthogonality between spreading code sequences is maintained. Therefore, the radio receiver can ensure the channel separation even when the desired signal and the interference signal are received together, and thus the interference signal component can be suppressed and the desired signal can be received with high quality. Become. Further, the second invention has an advantage that it can be applied even when the band used by the system is limited and the spread of the band is not allowed, that is, even when the shift of the center frequency described in the first invention cannot be used.

The present invention is also characterized in that each radio signal obtained by the spread modulation means is transmitted to a plurality of service areas by using polarized waves orthogonal to each other. With such a configuration, the reception level of the interference signal can be suppressed to some extent in the reception high-frequency stage in the wireless reception device, and the interference signal component can be further suppressed by the synergistic effect with the orthogonality between the spreading codes described above. It becomes possible to suppress more reliably.

A third aspect of the present invention is a radio transmission system for transmitting radio signals, which are code-division-multiplexed with different information, from a radio transmission device to a plurality of service areas adjacent to each other using the same frequency band. A plurality of spreading modulation means for respectively modulating the information to be transmitted to the plurality of service areas to the plurality of service areas by using spreading code sequences which are orthogonal to each other, and a plurality of wireless signals obtained by the spreading modulation means. And a monitor receiver is installed at a position where the plurality of service areas overlap each other, and the monitor receiver is provided for the plurality of service areas coming from the wireless transmitter. Receiving means for receiving each of the wireless signals and the wireless signals received by the receiving means. The phase difference detecting means for detecting the phase difference between the spread code sequences, and the timing correction information for reducing the phase difference detected by the phase difference detecting means to zero and notifying the radio transmitter. A timing correction instruction means for correcting the phase between the spreading code sequences used by the spreading modulation means in accordance with the timing correction information is provided.

Therefore, according to the present invention, the monitor receiver detects the phase difference between the spread codes in the radio signal for each service area coming from the radio transmitter, and the phase difference is used as the timing correction information as the radio transmitter. Will be notified. Then, according to the notified timing correction information, the wireless transmission device performs a correction process for reducing the phase difference between the spread codes used for each wireless signal to zero. For this reason, the orthogonality between the spreading codes used for the radio signals for each service area is always maintained accurately, and thus the separation between the desired signal and the interference signal in the radio receiving device is always maintained reliably. You can

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) In the first embodiment of the present invention, a carrier generating unit having a frequency offset function is provided in a wireless transmission device. Then, the carrier frequency generator shifts the center frequencies of the respective radio signals transmitted to the first and second service areas to each other by a frequency corresponding to the modulation rate (baud rate) of the transmission information. Is transmitted to each of the first and second service areas by using polarized waves orthogonal to each other.

FIG. 1 is a schematic configuration diagram showing a first embodiment of a wireless transmission system and a wireless transmission device according to the present invention, and BS1 is a wireless transmission device. The wireless transmission device BS1 is mounted on, for example, a broadcasting satellite or a communication satellite, and has two transmission systems corresponding to two different first and second service areas SA and SB. Each of these transmission systems has a transmission baseband unit (BBa, BBb) 1a, 1b and a modulation unit (MODa, BBa).
MODb) 2a and 2b, and transmitter (TXa, TXb) 3
a, 3b, transmitting antennas 4a, 4b, and carrier wave signal generating units 5a, 5b.

The transmission baseband units 1a and 1b temporarily convert a radio signal received by a satellite receiving unit (not shown) into baseband data, and perform predetermined reception such as deinterleaving or error correction decoding processing on the baseband data. Perform signal processing. Then, the baseband data after the reception signal processing is subjected to predetermined transmission signal processing such as error correction coding and interleaving, converted into a predetermined transmission format, and input to the modulators 2a and 2b.

The modulators 2a and 2b are the carrier signal generator 5
The carrier signals generated from a and 5b are digitally modulated by the transmission baseband data output from the transmission baseband units 1a and 1b, and the modulated carrier signals are output to the transmission units 3a and 3b.

The transmitters 3a and 3b are provided with the modulators 2a and 2b, respectively.
The modulated wave signal output from b is up-converted to a predetermined radio frequency, then amplified by the transmission power amplifier and supplied to the transmission antennas 4a and 4b.

The transmitting antennas 4a and 4b respectively transmit the radio frequency signals supplied from the transmitting units 3a and 3b to predetermined first and second service areas SA and SB. The first and second service areas S
A and SB are set in an area including Japan and an area including the Korean Peninsula, for example.

By the way, in the radio transmitter BS1 according to this embodiment, the carrier frequency generated by the carrier signal generators 5a and 5b is mutually shifted by the frequency Δf corresponding to the modulation rate of the transmission baseband data. Is set to. For example, if the carrier wave frequency generated by the carrier wave signal generator 5a is f, the carrier wave frequency generated by the carrier wave signal generator 5b is set to f + Δf.

Further, the transmitting antennas 4a and 4b are used to transmit the radio frequency signals supplied from the transmitting units 3a and 3b to the first and second service areas SA and SB, respectively. The polarization plane of the radio frequency signal for SA and the polarization plane of the radio frequency signal for the second service area SB are set to be orthogonal to each other.

With such a configuration, in the radio transmitter BS1, the transmission baseband data output from the transmission baseband units 1a and 1b are input to the modulation units 2a and 2b as modulation signals, respectively. Modulators 2a and 2b
Then, respectively, the carrier wave signals generated by the carrier wave signal generating units 5a and 5b are digitally modulated by the input transmission baseband data, whereby a modulated wave signal is generated. At this time, the carrier signal generator 5
The frequency of the carrier signal generated by b is the frequency f of the carrier signal generated by the carrier signal generator 5a.
On the other hand, it is offset in advance so as to be shifted by the frequency Δf corresponding to the modulation rate (baud rate) of the transmission baseband data. Therefore, the modulated wave signals output from the modulators 2a and 2b are signals whose center frequencies are mutually shifted by the frequency Δf.

In this way, the modulated wave signals output from the modulators 2a and 2b are frequency-converted into radio frequency signals in the 2.6 GHz band in the transmitters 3a and 3b, respectively, and then the predetermined transmission power is obtained. It is amplified to a level and supplied to the transmitting antennas 4a and 4b. Then, the first and second predetermined transmission antennas 4a and 4b are used.
Are transmitted to the service areas SA and SB. However, at this time, the radio frequency signals are set such that the planes of polarization are orthogonal to each other in the transmitting antennas 4a and 4b. Therefore, each service area SA,
Radio frequency signals whose polarization planes are orthogonal to each other are broadcast on the SB.

Therefore, assuming that the radio receiving device MS1 which wants to receive the radio frequency signal for the first service area SA is present in the boundary area between the service areas SA and SB, the radio receiving device MS1 is received. Device MS1
Then, the following receiving operation is performed.

That is, the reception antenna of the radio reception device MS1 is constructed so as to correspond to the plane of polarization of the radio frequency signal for the first service area SA. For this reason,
In the wireless reception device MS1, firstly the first
Radio frequency signal (desired signal) for the service area SA of
Only received. And since the local oscillation signal frequency of the receiver is tuned to the center frequency of the desired signal,
The desired signal is normally received and demodulated. Then, the received data reproduced by this demodulation is subjected to voice decoding processing, for example, and then is output as loudspeaker from the speaker.

On the other hand, since the plane of polarization of the radio frequency signal (interference signal) for the second service area SB is orthogonal to the receiving antenna of the wireless receiving device MS1, it is not received by the receiving antenna and is suppressed. It Further, even if it is received, the reception level becomes smaller than the desired signal. The received low-level interference signal has its center frequency shifted by Δf with respect to the center frequency of the desired signal, and is thus removed by the filter provided in the demodulation unit.

As described above, in the first embodiment, the radio transmitter BS1 is provided with the carrier wave generators 5a and 5b having the frequency offset function, and the carrier wave generators 5a and 5b allow the first and second service areas to be provided. The center frequencies f of the respective radio frequency signals transmitted to SA and SB are mutually shifted by a frequency Δf corresponding to the modulation rate (baud rate) of the transmission information, and further the respective center frequency shifted radio frequency signals. Using the polarizations orthogonal to each other
And the second service areas SA and SB, respectively.

Therefore, in the boundary area between the first and second service areas SA and SB, the radio receiving device MS
In No. 1, the interference signal is first suppressed by the receiving antenna whose polarization plane is orthogonal, and further suppressed by the filter which passes only the band of the demodulated signal of the desired signal. Therefore, it is possible to sufficiently suppress the interference signal component and receive and reproduce the desired signal with high quality. Moreover, since the shift width Δf of the center frequency is set to correspond to the baud rate of the transmission baseband data, when the demodulation component of the interference signal is removed by the filter, it does not affect the demodulation component of the desired signal and is effective. Can be removed.

(Second Embodiment) In the second embodiment of the present invention, each transmission baseband data to be transmitted to the first and second service areas is spread-modulated using spreading codes orthogonal to each other. A modulator is provided, and the radio frequency signal modulated by the modulator is transmitted to each service area using polarized waves orthogonal to each other.

FIG. 2 is a schematic configuration diagram showing a second embodiment of a wireless transmission system and a wireless transmission device according to the present invention. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

Radio transmitting apparatus BS according to the second embodiment
2 is also the wireless transmission device BS1 described in the first embodiment.
Similarly to the above, it is mounted on a broadcasting satellite or a communication satellite. Also, two different first and second service areas S
It has two transmission systems corresponding to A and SB. Each of these transmission systems has a transmission baseband unit (BBa,
BBb) 1a and 1b and modulator (MODa, MODb)
2a and 2b and transmitters (TXa and TXb) 3a and 3b
, Transmission antennas 4a and 4b, and code generators 6a and 6b
It has and.

Of these, the code generators 6a and 6b generate spreading code sequences PNa and PNb which are orthogonal to each other, and supply these spreading code sequences PNa and PNb to the modulators 2a and 2b, respectively. Spread code sequence PNa, PN
An orthogonal code such as a Walsh sequence is used as b.

The modulators 2a and 2b spread-modulate the digitally modulated carrier signals by the orthogonal spreading code sequences PNa and PNb generated from the code generators 6a and 6b. Then, the modulated carrier signal is transmitted to the transmitter 3a,
Output to 3b.

The transmitters 3a and 3b are connected to the modulators 2a and 2b, respectively.
The modulated wave signal output from b is up-converted to a predetermined radio frequency, then amplified by the transmission power amplifier and supplied to the transmission antennas 4a and 4b. Transmitting antenna 4
a and 4b respectively receive the radio frequency signals supplied from the transmitters 3a and 3b in the first and second service areas S, respectively.
Transmission to A and SB is performed, but at that time, the polarization of the radio frequency signal for the first service area SA and the polarization of the radio frequency signal for the second service area SB are set to be orthogonal to each other. To do.

With such a configuration, in the radio transmitter BS2, the transmission baseband data output from the transmission baseband units 1a and 1b are input to the modulation units 2a and 2b as modulation signals, respectively. Modulators 2a and 2b
First, the carrier signal generated by the carrier signal generators 5a and 5b is digitally modulated by the input transmission baseband data. Next, the digitally modulated carrier signal is converted into code generators 6a, 6
Spread modulation is performed by the orthogonal spreading code sequences PNa and PNb generated from b, and a modulated wave signal is thereby generated.

The modulated wave signals output from the modulators 2a and 2b are frequency-converted into radio frequency signals in the 2.6 GHz band, for example, in the transmitters 3a and 3b, respectively, and then are converted to predetermined transmission power levels. It is amplified and supplied to the transmitting antennas 4a and 4b. Then, these transmission antennas 4a and 4b are respectively transmitted to predetermined first and second service areas SA and SB.
However, at this time, the radio frequency signals are set such that the planes of polarization are orthogonal to each other in the transmitting antennas 4a and 4b. Therefore, each service area SA, SB
, A radio frequency signal whose polarization planes are orthogonal to each other is broadcast.

Therefore, in the state where it exists in the boundary area between the first and second service areas SA and SB, the radio frequency signal (desired signal) for the first service area SA is its polarization plane in the radio reception device MS2. It is received with high sensitivity by the receiving antenna having the same plane of polarization as. On the other hand, the radio frequency signal (interference signal) for the second service area SB is suppressed to some extent when it is received by the reception antenna because the polarization plane is orthogonal to the reception antenna.

Subsequently, in the radio receiving device MS2, the demodulation section calculates the correlation between the received desired signal and the received interference signal although the level is low. As a result of this correlation calculation, since the orthogonality between the spread code PNb of the interference signal and the orthogonal spread code PNa of the desired signal is maintained,
An interference signal component is not included in the signal after the despreading process. Thus, the interference signal is sufficiently suppressed, and as a result, the reception quality of the desired signal can be kept high.

As described above, in the second embodiment, each transmission baseband data to be transmitted to the first and second service areas SA and SB is spread-modulated by using spreading code sequences PNa and PNb which are orthogonal to each other. Then, the modulated radio frequency signal is transmitted to each of the service areas SA and SB using polarized waves orthogonal to each other.

Therefore, in the radio reception device MS2, even when the radio reception device MS2 exists in the boundary area between the first and second service areas SA and SB, the use of the reception antenna whose polarization plane is orthogonal to the interference signal and the spread code of the desired signal are used. The interference signal component is sufficiently suppressed by the correlation calculation process between PNa and the spread code PNb of the interference signal.

(Third Embodiment) In the third embodiment of the present invention, different information is used from the radio transmitter to the first and second service areas by using the same frequency band and by using the CDM method. In a wireless transmission system for transmitting each of the first and second service areas, a monitor receiving device is installed in a boundary area between the first and second service areas, and in the monitor receiving device, the first and second services coming from the wireless transmitting device. Each radio frequency signal for the area is received, and the phase difference between the spreading code sequences used for these radio frequency signals is detected. Then, timing correction information for making the phase difference zero is generated and notified to the wireless transmission device, and the wireless transmission device corrects the phase between the spread code sequences according to the timing correction information. is there.

FIG. 3 is a schematic configuration diagram showing a third embodiment of a wireless transmission system and a wireless transmission device according to the present invention. In the figure, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals and detailed description thereof will be omitted.

First and second service areas SA, S
In the boundary area of B, the monitor receiver MMS is fixedly installed. This monitor receiver MMS is used for the spread code PNa used for the radio frequency signal for the first service area SA and the radio frequency signal for the second service area SB coming from the radio transmitter. It has a function of detecting a reception phase difference from the spread code PNb, generating timing correction information for making the phase difference close to zero, and notifying it to the wireless transmission device BS3.

FIG. 4 is a circuit block diagram showing the structure of the monitor receiver MMS. In the figure, the first and second service areas S coming from the wireless transmission device BS3
The radio frequency signals for A and SB are received by the reception antenna 61, then branched into two by the antenna duplexer (DUP) 62 and input to the reception units (RXa, RXb) 63a and 63b, respectively. The reception units 63a and 63b respectively frequency-convert the received radio frequency signal for the first service area SA and the received radio frequency signal for the second service area SB, and use the received signal as a phase detection unit (DET).
a, DETb) 64a, 64b.

The phase detectors 64a and 64b respectively extract the spread codes PNa and PNb from the received signals input from the receivers 63a and 63b and detect their phases.
A matched filter, for example, can be used to extract the spread codes PNa and PNb and detect the phase thereof. Then, each detected phase is input to the phase difference detection unit (PD) 65. The phase difference detection unit 65 compares the input detected phases to detect the phase difference, and gives the detection result of the phase difference to the timing correction information generation unit (GEN) 66.

The timing correction information generator 66 generates timing correction information for making the detected value of the phase difference closer to zero when the detected value of the phase difference exceeds a predetermined value, and the network interface unit (NETI). / F) 67. The network interface unit 67 inserts the timing correction information into packet data and transmits the packet data to a ground station (not shown) via the communication network NW including the Internet. The ground station extracts the timing correction information from the transmitted packet and notifies the timing correction information to the wireless transmission device BS3 via the satellite control channel. A dedicated line network or a general wire telephone network can be used as the communication network NW.

On the other hand, the radio transmitter BS3 is provided with a code generator 5 having a phase control function. FIG. 5 is a circuit block diagram showing the configuration. This code generator 5
Are code generators 51a and 51b for generating spread codes PNa and PNb whose phases are orthogonal to each other, and a phase controller 52.
And a receiver 53.

The receiver 53 is the monitor receiver MMS.
From the communication network NW. The phase controller 52 adjusts the phases of the orthogonal spreading codes PNa and PNb generated by the code generators 51a and 51b according to the received timing correction information so that the reception phase difference in the monitor receiver MMS approaches zero. Controlled and phase controlled orthogonal spreading code PN
a 'and PNb' are given to the modulators 2a and 2b, respectively.

With such a configuration, it is assumed that the phases of the orthogonal spreading codes PNa and PNb have changed due to the characteristic changes of the code generators 51a and 51b in the radio transmitter BS3. Then, in the monitor receiver MMS, the spreading code PNa used for the radio frequency signal for the first service area SA and the spreading code PN used for the radio frequency signal for the second service area SB.
The phase difference with b is detected by the phase difference detection unit 65. Then, the timing correction information for making the phase difference close to zero is generated by the timing correction information generation unit 66,
This timing correction information is transmitted to the radio transmission device BS3 mounted on the satellite via the communication network NW and a ground station (not shown).
Will be notified.

In the radio transmitter BS3, when the timing correction information is notified, the phase controller 52 causes the orthogonal spreading code PN generated from the code generators 51a and 51b.
The phases of a and PNb are controlled in accordance with the notified timing correction information, and the phase-controlled orthogonal spreading code PN is controlled.
a 'and PNb' are given to the modulators 2a and 2b. Therefore, in the modulators 2a and 2b, thereafter, spread modulation processing is performed using the orthogonal spread codes PNa 'and PNb' whose phases are corrected, and the modulated radio frequency signals are transmitted from the transmission antennas 4a and 4b, respectively. It is transmitted to the first and second service areas SA and SB.

As described above, in the third embodiment, the monitor receiver MMS is installed in the boundary area between the first and second service areas SA and SB, and the monitor receiver MMS is installed here.
Spread code PNa used for radio frequency signals for A
And the spread code PNb used for the radio frequency signal for the second service area SB is detected, timing correction information for making the phase difference close to zero is generated, and the radio transmitter BS3 is generated. Notifying. Then, in the wireless transmission device BS3, the phases of the orthogonal spreading codes PNa and PNb generated from the code generators 51a and 51b are controlled according to the notified timing correction information.

Therefore, in the radio receiving apparatus existing in the boundary area between the first and second service areas SA and SB, the spread code PNa used for the received radio frequency signal for the first service area SA, The orthogonality with the spread code PNb used in the received radio frequency signal for the second service area SB is always maintained, whereby the interference signal component can be stably suppressed.

The present invention is not limited to the above embodiments. For example, the shift of the center frequency described in the first embodiment and the use of the orthogonal spreading code described in the second embodiment may be used together.

In each of the above-mentioned embodiments, the plane of polarization of the radio frequency signal for the first service area SA and the second service area SB in the antennas 4a and 4b are used.
Although the plane of polarization of the radio frequency signal for direct transmission was made orthogonal to each other, if the sufficient interference suppression effect can be obtained only by shifting the center frequency or using the orthogonal spreading code, the orthogonalization of this plane of polarization is omitted. You may.

In each of the above embodiments, the case where the wireless transmission device is mounted on a broadcasting satellite or a communication satellite has been described as an example, but the present invention is not limited to this. For example, a radio transmission device is installed in a ground station, and radio frequency signals for each service area SA and SB are transmitted from the ground station to a broadcasting satellite or a communication satellite, and relayed by a transponder mounted on the satellite to relay the signals on the ground. It may be configured to broadcast to each service area SA, SB. With this configuration, the reliability of the modulator and the like can be ensured and the cost can be reduced as compared with the case where the wireless transmission device is mounted on the satellite.

In each of the above-mentioned embodiments, a system using a satellite has been described as an example, but the present invention can be applied to a broadcasting system and a mobile communication system using a terrestrial wave. In this case, the wireless transmission device is provided in the terrestrial broadcasting station or the relay station, or the mobile communication base station.

In addition, the type and configuration of the wireless transmission system, the installation locations and configurations of the wireless transmitter and the monitor receiver, the number and size of service areas, etc.
Various modifications can be implemented without departing from the scope of the present invention.

[0058]

As described above in detail, in the first aspect of the invention, the radio transmitter is additionally provided with frequency offset means, and the center frequency of each radio signal transmitted to a plurality of service areas is provided by the frequency offset means. The radio signals are shifted from each other by a frequency corresponding to an integer multiple of the modulation speed of the information to be transmitted, and the radio signals whose center frequencies are shifted are transmitted to the plurality of service areas, respectively. .

According to the second aspect of the invention, the radio transmitter is provided with a spreading modulation means for modulating each information to be transmitted to the plurality of service areas by using spreading codes orthogonal to each other. Each of the received wireless signals is transmitted to each of a plurality of service areas.

Further, in the third invention, a monitor receiver is installed at a position where a plurality of service areas overlap each other, and in this monitor receiver, each radio signal for the plurality of service areas coming from the radio transmitter is respectively received. Upon reception, the phase difference between the spreading code sequences used for each received radio signal is detected. Then, timing correction information for making the detected phase difference zero is generated and notified to the wireless transmission device, and the phase between the spreading code sequences used by the spreading modulation means is corrected according to the timing correction information. I am trying.

Therefore, according to these inventions, even in the boundary area of a plurality of service areas, a wireless transmission system capable of effectively suppressing an interference signal and receiving a desired signal with high quality, and its wireless transmission. A device and a monitor receiver can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a wireless transmission system and a wireless transmission device according to the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of a wireless transmission system and a wireless transmission device according to the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment of a wireless transmission system and a wireless transmission device according to the present invention.

FIG. 4 is a circuit block diagram showing a configuration of a monitor receiver of the system shown in FIG.

5 is a circuit block diagram showing a configuration of a code generation unit of the wireless transmission device shown in FIG.

[Explanation of symbols]

BS1, BS2, BS3 ... Radio transmission devices SA, SB ... Service areas MS1, MS2 ... Radio reception device MMS ... Monitor reception device NW ... Communication networks 1a, 1b ... Transmission baseband processing units (BBa, BB)
b) 2a, 2b ... Modulating section (MODa, MODb) 3a, 3b ... Transmitting section (TXa, TXb) 4a, 4b ... Transmitting antennas 5a, 5b ... Carrier signal generating sections 6a, 6b ... Code generator 5 ... Code generating section 51a, 51b ... Code generator 52 ... Phase control section 53 ... Timing correction information receiving section 61 ... Receiving antenna 62 ... Antenna duplexer (DUP) 63a, 63b ... Receiving section (RXa, RXb) 64a, 64b ... Phase detecting section (DETa, DETb) 65 ... Phase difference detection unit (PD) 66 ... Timing correction information generation unit (GEN) 67 ... Network interface unit (NETI / F) PNa, PNb ... Orthogonal code sequence PNa ', PNb' ... After phase correction Orthogonal code sequence of

Claims (8)

[Claims] 1. A radio transmission apparatus for transmitting radio signals obtained by code division multiplexing different information to a plurality of adjacent service areas using the same frequency band, wherein the radio signals are transmitted to the plurality of service areas. Frequency offset means for mutually shifting the center frequency of each radio signal by a frequency corresponding to an integer multiple of the modulation rate of the information transmitted by the radio signal, and each radio signal whose center frequency is shifted by the frequency offset means. And a transmission means for respectively transmitting to each of the plurality of service areas. 2. The transmitting means transmits, to the plurality of service areas, respective radio signals whose center frequencies are shifted by the frequency offset means, using polarized waves orthogonal to each other. The wireless transmission device according to item 1. 3. A radio transmitting apparatus for transmitting radio signals obtained by code division multiplexing different information to a plurality of service areas adjacent to each other using the same frequency band, wherein the radio signals are transmitted to the plurality of service areas. And a transmission means for respectively transmitting the respective radio signals obtained by the spread modulation means to the plurality of service areas. A wireless transmission device. 4. The transmission means transmits each radio signal obtained by the spread modulation means to the plurality of service areas using polarized waves orthogonal to each other. Wireless transmitter. 5. A radio transmission system for transmitting radio signals, which are code-division-multiplexed with different information, from a radio transmission device to a plurality of service areas adjacent to each other using the same frequency band. A monitor receiving device is installed at a position where the areas overlap with each other, and the wireless transmitting device modulates each information to be transmitted to the plurality of service areas using spreading code sequences orthogonal to each other, and a spreading modulation means, Each of the radio signals obtained by the modulation means, and a transmitting means for respectively transmitting to the plurality of service areas, the monitor receiving device, each wireless signal for the plurality of service areas coming from the wireless transmission device Is used for each of the wireless reception signals received by the receiving means and the receiving means. Phase difference detecting means for detecting a phase difference between the scattered code sequences, and timing correction information for making the phase difference detected by the phase difference detecting means zero, which is notified to the wireless transmission device, and this timing A radio transmission system, comprising: a timing correction instruction means for correcting the phase between the spreading code sequences used by the spreading modulation means according to the correction information. 6. A radio transmission device for transmitting radio signals obtained by code division multiplexing different information to a plurality of service areas adjacent to each other using the same frequency band, and the plurality of service areas overlapping each other. Detects the phase difference between spreading code sequences that are installed in the position and are used for each radio signal for the plurality of service areas coming from the radio transmitter, and correct the timing based on the detection result of this phase difference. A wireless transmission device used in a wireless transmission system, comprising: a monitor reception device for generating information and notifying the wireless transmission device, wherein each information to be transmitted to the plurality of service areas is orthogonal to each other. Spreading modulation means for respectively modulating using a code sequence, and each radio signal obtained by this spreading modulation means to the plurality of service areas. The spreading modulation means is used to set the phase difference between the spreading code sequences detected by the monitor receiving device to zero according to the timing correction information notified from the monitor receiving device. And a phase control means for controlling the phase between the spreading code sequences. 7. The transmission means transmits each radio signal obtained by the spread modulation means to the plurality of service areas using polarized waves orthogonal to each other. Wireless transmitter. 8. The information to be transmitted to a plurality of service areas adjacent to each other is respectively modulated by using spreading code sequences which are orthogonal to each other, and the respective radio signals generated by this modulation are directed to the plurality of service areas and are the same. A monitor receiving device used together with a wireless transmitting device for transmitting using a frequency band, wherein each wireless signal for the plurality of service areas coming from the wireless transmitting device at a position where the plurality of service areas overlap each other. And a phase difference detecting means for detecting a phase difference between the spread code sequences used for the radio signals received by the receiving means, and a phase difference detected by the phase difference detecting means. Is generated and notified to the wireless transmission device, and according to this timing correction information, A monitor receiving device, comprising: a timing correction instructing means for correcting a phase between spreading code sequences used by the wireless transmitting device.