JP2005295088A - Wireless communication system and wireless communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a communication failure caused by frequency drift of a radio signal in a radio communication system composed of a base station and a mobile station without causing an increase in cost of the mobile station.
Communication apparatuses 10 and 30 perform wireless communication by up-converting a transmission signal and down-converting a reception signal. The base station side communication device 10 up-converts and transmits a pilot signal Tp having a constant frequency f0 together with the transmission signal, and the mobile station side communication device 30 up-converts the pilot signal after down-conversion together with the transmission signal. Then, it transmits to the base station side. Then, the base station-side communication apparatus 10 down-converts the received signal, extracts the pilot signal Rp, and increases and decreases the frequency of the received pilot signal Rp and the frequency of the transmitted pilot signal Tp so as to match. The frequencies of the local signals f1c and f2c used for conversion are corrected.
[Selection] Figure 1

Description

  The present invention relates to a wireless communication system for a mobile body including a base station and a mobile station that can wirelessly communicate with each other and a wireless communication apparatus suitable for realizing this system.

  Conventionally, as a radio communication system capable of preventing frequency drift (Doppler shift) of a radio signal that occurs when radio communication is performed between an earth station and a satellite, a pilot having a constant frequency is used for a signal transmitted from the earth station to the satellite. It is known that the signal is superimposed, and the satellite side detects the difference between the frequency of the received pilot signal and the original frequency as the amount of Doppler shift, and shifts the frequency of the received signal by the detected amount of Doppler shift. (See, for example, Patent Document 1).

In addition, as a wireless communication system that can prevent frequency drift (Doppler shift) that occurs when communication is performed between a base station and a mobile station, a GPS receiver is mounted on the mobile station side, and the mobile station to the base station When transmitting data, the base station side calculates the Doppler shift amount based on the moving speed detected by the GPS receiver and shifts the frequency of the transmission signal from the original frequency by the Doppler shift amount. There is also known one that can receive data from a mobile station without being affected by a Doppler shift (see, for example, Patent Document 2).
JP 2003-134002 A JP 2003-309517 A

  However, in the former technique, the same pilot signal as that of the earth station (in other words, the base station) is generated on the satellite side in order to detect the Doppler shift amount of the received signal on the satellite side (in other words, the mobile station side). In order to make the frequency of the pilot signal of each station coincide with each other, it is necessary to make the oscillator of the pilot signal provided in each station expensive with a stable oscillation frequency, This increases the cost of the entire radio communication system, and cannot be adopted in a system that is composed of a base station and a large number of mobile stations such as a radio telephone network and requires cost reduction of the mobile stations.

In the latter technique, since a GPS receiver must be mounted on the mobile station, the cost of the mobile station is increased and the same problem as described above occurs.
The present invention has been made in view of these problems, and in a wireless communication system including a base station and a mobile station, the frequency drift of a wireless signal (specifically, the mobile station) can be achieved without increasing the cost of the mobile station. The purpose is to prevent a communication failure caused by a Doppler shift associated with the movement of.

  In the wireless communication system according to claim 1, wherein the base station transmits a transmission signal to a mobile station, the transmission signal and a pilot signal of a specific frequency are simultaneously up-converted. The signal after the up-conversion is transmitted from the antenna.

  On the other hand, the mobile station receives the transmission signal from the base station by the antenna and down-converts the reception signal to restore the original transmission signal and pilot signal transmitted by the base station. Further, the mobile station up-converts the restored pilot signal together with the transmission signal to be transmitted to the base station, and transmits the signal after the up-conversion as a transmission signal to the base station from the antenna.

  On the base station side, the transmission signal from the mobile station is received via the antenna, and the received signal is down-converted to restore the transmission signal and pilot signal transmitted by the mobile station. The restored pilot signal (hereinafter also referred to as a received pilot signal) is compared with the frequency of a pilot signal (hereinafter also referred to as a transmitted pilot signal) transmitted to the mobile station, and the frequencies of these pilot signals match. As described above, the frequencies of the first local signal and the second local signal used for up-conversion of the transmission signal and down-conversion of the reception signal are corrected by the same frequency.

  In other words, in the radio communication system of the present invention, the reception local signal used to downconvert the received signal on the mobile station side and the transmission signal used to upconvert the transmission signal on the mobile station side as well. Each local signal is fixed at a constant frequency.

  For this reason, if the mobile station is stopped and no frequency drift (Doppler shift) occurs in the radio signal, the first local station signal used for up-converting the transmission signal on the base station side, and the base station If the second local station signal used for down-converting the received signal on the side matches the frequency of the local station signal for reception on the mobile station side and the frequency of the local station signal for transmission on the mobile station side, Wireless communication with a station can be performed without any problems.

  However, when the mobile station moves and a frequency drift (Doppler shift) occurs in the radio signal, the frequency of the first local oscillation signal and the reception local oscillation signal, and the second local oscillation signal and the transmission local oscillation signal. And the frequency of the received signal obtained at each station deviates from the frequency of the original transmission signal.

  Therefore, in the present invention, one pilot signal is transmitted / received between the base station and the mobile station, and the frequency fluctuation for one round trip of the pilot signal caused by the transmission / reception is detected on the base station side so that this frequency fluctuation is eliminated. In addition, the first local oscillation signal used for up-conversion of the transmission signal and the second local oscillation signal used for down-conversion of the reception signal are corrected by the same frequency, so that each local oscillation signal is reduced by half of the frequency fluctuation. Each frequency is corrected individually.

  As a result, each of the base station and the mobile station can accurately restore the original transmission signal transmitted by the communication partner by down-converting the received signal, thereby preventing a communication failure caused by the movement of the mobile station.

  In order to obtain this effect, the present invention generates a pilot signal on the base station side or compares the frequencies of the transmission pilot signal and the reception pilot signal, but the mobile station side simply receives the received pilot signal. It is only necessary to retransmit the signal, and there is no increase in the cost of the mobile station in realizing the present invention.

  Therefore, according to the wireless communication system of the present invention, for example, it can be easily applied to a system configured with a base station and a large number of mobile stations, such as a wireless telephone network, where cost reduction of the mobile station is required. Yes, it can demonstrate its effect.

  In addition, when the present invention is applied to a wireless communication system in which a large number of mobile stations exist for one base station, it is necessary to be able to identify the communication partner on the base station side. For this purpose, for example, as described in claim 2, the base station performs amplitude modulation on the pilot signal with the identification information of the mobile station to be communicated during wireless communication with the mobile station, thereby converting the pilot signal into a pilot signal. When identification information of a mobile station to be communicated is given, and the mobile station demodulates the identification information from the pilot signal extracted from the down-converted received signal, and the demodulated identification information is its own identification information Or a reception operation for receiving a reception signal after extraction of a pilot signal as a transmission signal from a base station and a transmission operation for transmitting the transmission signal to the base station. Thus, during wireless communication with the base station, the mobile station gives its own identification information to the pilot signal by amplitude-modulating the pilot signal transmitted to the base station with its own identification information. The identification information may be demodulated from the pilot signal extracted from the received signal after conversion, and the mobile station that is the communication partner may be recognized from the demodulated identification information.

  In other words, in this way, on the base station side, wireless communication is performed while designating a mobile station to be a communication partner using a pilot signal, or a mobile station that has transmitted a received signal from a received pilot signal Can be recognized, and the base station can perform good wireless communication with a plurality of mobile stations. In addition, it goes without saying that the one-to-many communication between the base station and the plurality of mobile stations can be performed more satisfactorily by combining the technology described in claim 2 and the technology described in claim 3 with each other. Absent.

  In addition, since the pilot signal can transmit desired information not only by detecting the frequency fluctuation (Doppler shift) accompanying the movement of the moving body but also by modulating the amplitude, for example, according to claim 4. As described above, a base station is provided with a satellite antenna that selectively receives one of two types of radio waves transmitted from a communication satellite and has a frequency converted into a broadcast signal in a predetermined frequency band. In the case where the broadcast signal from the satellite antenna is configured to be up-converted together with the transmission signal and the pilot and transmitted to a specific mobile station, the mobile station side serving as the broadcast signal receiving device By modulating the amplitude of the pilot signal, the polarization plane of the received radio wave by the satellite antenna on the base station side can be switched.

  In other words, in the radio communication system according to claim 4, the mobile station biases the pilot signal transmitted to the base station into the pilot signal by amplitude-modulating the pilot signal with information designating the polarization plane of the radio wave received by the satellite antenna. Wave base designation information is added, and the base station demodulates the polarization plane designation information from the pilot signal extracted from the down-converted received signal, and the polarization plane of the radio wave received by the satellite antenna according to the demodulated designation information Therefore, on the mobile station side serving as a broadcast signal receiver, the plane of polarization of the radio wave received by the satellite antenna provided in the base station can be switched, and satellite broadcasting from the base station to the mobile station can be performed. The usability of the distributed system can be improved.

  On the other hand, the invention described in claim 5 relates to a wireless communication apparatus used as a base station for performing wireless communication with a mobile station, and generates an antenna for wireless communication and a pilot signal of a specific frequency. Pilot signal generating means, first local oscillating means for generating a first local oscillation signal having a predetermined frequency required for up-converting a transmission signal to be transmitted to the mobile station, and down-converting the transmission signal from the mobile station A second local oscillation means for generating a second local oscillation signal of a predetermined frequency required for the transmission, a pilot signal from the pilot signal generation means and a transmission signal to be transmitted to the mobile station, and the first local oscillation means The first frequency conversion means for up-conversion using the signal generated from the first station generated and transmitting the up-converted signal from the antenna as a transmission signal to the mobile station And a second frequency converting means for down-converting the received signal from the antenna using the second local oscillation signal generated by the second local oscillating means, and the received signal down-converted by the second frequency converting means. Pilot signal extracting means for extracting the pilot signal from the pilot signal and outputting the received signal after extraction of the pilot signal to the internal circuit as a transmission signal from the mobile station, and the pilot signal and pilot signal generating means extracted by the pilot signal extracting means And a local oscillation frequency correction means for correcting the oscillation frequency of the first local oscillation means and the second local oscillation means by the same frequency so that the frequencies of the pilot signals are compared and the frequencies of these pilot signals are matched. , Provided.

  Therefore, according to the wireless communication apparatus of the fifth aspect, it can be used as a base station in the wireless communication system of the first aspect, and as a result, the same effect as in the first aspect can be obtained. it can.

  Further, the invention according to claim 6 is a wireless communication device mounted on a mobile body and used as a mobile station for performing wireless communication with a base station, wherein the wireless communication antenna, Local oscillation means for generating a transmission local oscillation signal required for up-converting a transmission signal to be transmitted to the station, and a constant frequency required for down-converting the transmission signal from the base station A receiving local oscillation means for generating a receiving local oscillation signal, a receiving frequency converting means for down-converting the received signal from the antenna using the receiving local oscillation signal generated by the receiving local oscillation means, and a receiving A pilot that extracts a pilot signal from the received signal down-converted by the frequency conversion means, and outputs the received signal after extraction of the pilot signal to the internal circuit as a transmission signal from the base station. And the signal extracted from the pilot signal extracting means and the transmission signal to be transmitted to the base station are mixed, and up-conversion is performed using the local signal for transmission generated by the local oscillation means for transmission. And a frequency conversion means for transmission for transmitting the up-converted signal from the antenna as a transmission signal to the base station.

  Therefore, according to the radio communication apparatus of the sixth aspect, it can be used as a mobile station in the radio communication system according to the first aspect, and as a result, the same effect as in the first aspect can be obtained. it can.

  Further, the invention according to claim 7 is the radio communication apparatus according to claim 5 or 6, wherein the modulation means for modulating the pilot signal to be up-converted together with the transmission signal, and the pilot signal extraction means At least one of demodulation means for demodulating original information obtained by modulating the amplitude of the pilot signal from the extracted pilot signal is provided.

  That is, in the wireless communication device according to claim 5 or 6, if a modulation means for amplitude-modulating a pilot signal transmitted to a communication partner is provided, desired information (described above) is transmitted to the communication partner by amplitude modulation of the pilot signal. Identification information, satellite antenna polarization switching information, etc.), and conversely, if a demodulation means for demodulating the original information from the received pilot signal is provided, the pilot signal is amplitude-modulated from the communication partner. The pilot signal used to prevent unnecessary reception associated with frequency drift (Doppler shift) of the radio signal can be effectively used as an information transmission medium. Is possible.

Embodiments of the present invention will be described below.
[First Embodiment]
FIG. 1 is an explanatory diagram showing the configuration of a wireless communication system according to a first embodiment to which the present invention is applied.

  As shown in FIG. 1, the wireless communication system of this embodiment includes a base station side data management device 2 installed at a specific location and a plurality of data communication terminals mounted on a plurality of mobile bodies moving around the base station side. 4 for transmitting a transmission signal to be transmitted / received to / from 4 bidirectionally using wireless communication, and a communication device 10 on the base station side and a plurality of communication devices 30 on the mobile body side serving as a mobile station. (Only one is shown in the figure).

  Here, first, the data management device 2 is configured to output, for example, a transmission signal Tx having a frequency of 1.5 to 2 GHz as a transmission signal to be transmitted to the communication device 30 on the mobile body side. The transmission signal Tx is mixed with the oscillation signal (first local oscillation signal: approximately 12.5 GHz) fc1 from the first local oscillator 12 by the mixer 13, thereby making the transmission signal Tx a predetermined frequency band (approximately 14). Up-convert to a transmission signal of ˜14.5 GHz band).

  In addition, the communication device 10 includes a local oscillator 21 that generates a pilot signal (transmission pilot signal) Tp having a constant frequency fo (for example, 1.25 GHz). The transmission pilot signal Tp is sent to the ASK modulator 22. After being amplitude-modulated, the signal is mixed with the transmission signal Tx via the mixer 23 and is up-converted to a predetermined frequency (13.75 GHz in this embodiment) together with the transmission signal Tx by the mixer 13.

  Then, the transmission signal and the pilot signal after the up-conversion are input to the amplifier 15 through a band pass filter (hereinafter referred to as BPF) 14, amplified to a predetermined level by the amplifier 15, and then passed through the filter 16. Are transmitted to the antenna 11 and radiated from the antenna 11 to the surroundings as radio signals.

  Next, the radio signal radiated from the antenna 11 is received by the antenna 31 of the communication device 30 mounted on the mobile body around the base station. The received signal is input to the amplifier 33 via the filter 32 in the communication device 30, amplified to a predetermined level by the amplifier 33, and then input to the mixer 35.

  The mixer 35 mixes the reception signal input via the amplifier 33 with the oscillation signal (reception local oscillation signal: 12.5 GHz) f1o from the reception local oscillator 34, thereby down-converting the reception signal. The down-converted received signal is input to the amplifier 37 via the BPF 36, amplified to a predetermined level by the amplifier 37, and then input to the pilot separation circuit 38.

The pilot separation circuit 38 is for extracting the pilot signal PILOT from the down-converted received signal.
Next, the reception signal from which pilot signal PILOT has been removed by pilot separation circuit 38 is output to data communication terminal 4, and pilot signal PILOT extracted from the reception signal by pilot separation circuit 38 is sent to ASK demodulator 45. It is input to the amplifier 46 as well as being input.

  The pilot signal PILOT input to the amplifier 46 is amplified to a predetermined level, then amplitude-modulated by the ASK modulator 47, and then the base station output from the data communication terminal 4 via the mixer 48 Is mixed with a transmission signal (in this embodiment, 0.5 to 1.0 GHz).

  The transmission signal mixed with the pilot signal PILOT is mixed with the oscillation signal (transmission local oscillation signal: 11.75 GHz) f2o from the transmission local oscillator 41 by the mixer 42, so that a predetermined frequency band ( In this embodiment, it is up-converted to 12.25-12.75 GHz and the pilot signal is approximately 13 GHz.

  The transmission signal and pilot signal after the up-conversion are input to the amplifier 44 via the BPF 43, amplified to a predetermined level by the amplifier 44, and then transmitted to the antenna 31 via the filter 32. Is emitted to the surroundings as a radio signal.

  Next, the radio signal radiated from the antenna 31 is received by the antenna 11 of the communication device 10 on the base station side, and the received signal is input to the amplifier 17 through the filter 16 and is predetermined by the amplifier 17. After being amplified to the level, it is input to the mixer 19.

  The mixer 19 mixes the reception signal input via the amplifier 17 with the oscillation signal (second local oscillation signal: approximately 11.75 GHz) f2c from the second local oscillator 18, thereby down-converting the reception signal. .

  The down-converted reception signal is input to the pilot separation circuit 24 via the BPF 20, and the pilot separation circuit 24 converts the reception signal Rx and the reception pilot signal Rp to be output to the data management device 2. To be separated.

  The reception signal Rx from which the reception pilot signal Rp has been removed by the pilot separation circuit 24 is output to the data management device 2, and the reception pilot signal Rp extracted from the reception signal by the pilot separation circuit 24 is sent to the ASK demodulator 25. It is input to the frequency comparison unit 27 and the frequency control unit 28 as well.

Each of the communication devices 10 and 30 includes communication control units 26 and 49 each including a microcomputer.
And the communication control part 26 by the side of the communication apparatus 10 receives the instruction | command from the data management apparatus 2, gives the command for a mobile station simultaneous call to the transmission pilot signal Tp by driving the ASK modulator 22, Send to nearby mobile objects.

  Further, in the communication device 30 on the mobile unit side, the communication control unit 49 monitors the demodulated data from the ASK demodulator 45, and when the simultaneous call command is demodulated by the ASK demodulator 45, the data communication terminal 4 Inquires whether there is data to be transmitted to the base station side, and if there is data to be transmitted, drives the ASK modulator 47 to give the pilot signal its own identification information and a communication request command And transmit it to the base station.

  For this reason, after the communication control unit 26 on the communication device 10 side transmits the transmission pilot signal Tp modulated by the mobile station simultaneous call command by driving the ASK modulator 22 as described above. The ASK demodulator 25 waits for the communication request command to be demodulated. When the communication request command is demodulated, the mobile station identification information transmitted along with the command is acquired.

  Thereafter, the ASK modulator 22 is driven by the response command to which the identification information is added, and the transmission pilot signal Tp to which the response command is added is transmitted, so that a specific mobile station (communication) corresponding to the identification information is transmitted. The device 30) is permitted to communicate, and thereafter, various data are transmitted to and received from the mobile station (communication device 30) that has permitted the communication.

  Next, the frequency comparison unit 27 compares the frequency of the reception pilot signal Rp input from the pilot separation circuit 24 and the transmission pilot signal Tp generated by the local oscillator 21, and a voltage signal Vdf corresponding to the difference in frequency. Is generated.

  Then, the frequency control unit 28 sets the first local oscillator 12 and the first local oscillator 12 so that the voltage signal Vdf output from the frequency comparison unit 27 is zero, that is, the frequencies of the reception pilot signal Rp and the transmission pilot signal Tp match. The oscillation frequency of the two local oscillators 18 is corrected by the same frequency.

  That is, in the present embodiment, the first local oscillator 12 and the second local oscillator 18 are configured by frequency variable type local oscillators, and the frequency control unit 28 sets the oscillation frequency of each of these local oscillators 12 and 18. Reference voltage sources 51 and 52 for generating reference voltages Vto and Vro for controlling to the same reference frequencies f1o and f2o as the local oscillators 34 and 41 in the mobile communication device 30 are provided (see FIG. 2).

  As shown in FIG. 2, the frequency control unit 28 includes a detection circuit 61 that detects the reception pilot signal Rp, a determination circuit 62 that determines the presence or absence of the reception pilot signal Rp based on the output from the detection circuit 61, A switch 54 that is switched on when the determination circuit 62 determines that the received pilot signal Rp is present and takes in the voltage signal Vdf from the frequency comparison unit 27 is provided.

  When the determination circuit 62 determines that there is no reception pilot signal Rp, the output circuit 60 is switched as shown in the figure, and the reference voltages Vto and Vro output from the reference voltage sources 51 and 52 are used as the local oscillator 12. , 18 are output as control voltages Vt, Vr, and the oscillation frequencies of the local oscillators 12, 18 are controlled to the reference frequencies f1o, f2o.

  On the other hand, when the determination circuit 62 determines that the received pilot signal Rp is present, the switch 54 is turned on and the voltage signal Vdf from the frequency comparison unit 27 is input, the voltage signal Vdf is converted into an integration circuit (in other words, Then, the integration is performed by the low-pass filter 55, and the integration result is input to the two adder circuits 57 and 58 via the distributor 56.

  Then, in each of the adder circuits 57 and 58, the integrated value (voltage) input via the distributor 56 is added to the output from the reference voltage sources 51 and 52 (that is, the reference voltages Vto and Vro). The outputs from 57 and 58 are output via the output circuit 60 as the control voltages Vt and Vr of the local oscillators 12 and 18.

  That is, when the pilot signal transmitted from the mobile communication device 30 is received, the frequency control unit 28 compares the frequency of the received pilot signal Rp and the transmitted pilot signal Tp, and each of these signals Rp, The oscillation frequencies of the local oscillators 12 and 18 are corrected by the same frequency so that the frequencies of Tp coincide with each other.

  Therefore, according to the wireless communication system of the present embodiment, the mobile body on which the communication device 30 that performs wireless communication with the communication device 10 on the base station side moves, and the frequency drift (Doppler shift) occurs in the wireless signal. When this occurs, it is possible to prevent a communication failure from occurring due to fluctuations in the frequency of the received signal obtained on the side of each communication device 10 and 30 due to the frequency drift.

  In particular, in this embodiment, since the reception characteristics of the communication devices 10 and 30 are improved only by the communication device 10 on the base station side, the cost of the communication device 30 on the mobile body serving as a mobile station is increased. Therefore, the present invention can be easily applied even to a wireless communication system that includes a base station and a large number of mobile stations and requires cost reduction of the mobile station.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken within the technical scope of this invention.
For example, in the above embodiment, the base station side communication apparatus 10 has been described as performing one-to-many communication with a plurality of communication apparatuses 30, but in the present invention, the base station and the mobile station always perform one-to-one communication. Even a wireless communication system configured as described above can be applied.

  In this case, for example, as shown in FIG. 3, a communication device 70 serving as a base station includes a BS / CS antenna 5 installed on a rooftop of a building and a network (in-building network) built in the building. The BS / CS tuner 8 mounted on the mobile body is connected to the HUB 6 connected to the mobile station via the communication device 80 mounted on the specific mobile body. And a communication system configured to connect the information terminal 7 such as a personal computer (PC) mounted on the mobile body to the network in the building via the HUB 6 and the communication device 80 on the mobile body side. Even applicable.

Hereinafter, this communication system will be described as a second embodiment of the present invention.
[Second Embodiment]
First, the BS / CS antenna 5 is a satellite broadcast receiving antenna that receives a satellite broadcast distributed via a broadcasting satellite (BS) or a communication satellite (CS), and is a reflecting mirror 5a and a reflecting mirror via a support arm. The receiving unit 5b is disposed at the focal position 5a.

  When receiving 15 VDC from the communication device 70, the receiving unit 5b receives a right-handed circularly polarized wave out of the transmission radio wave from the broadcasting satellite (BS) and the transmission radio wave from the communication satellite (CS). The received signal is down-converted to an intermediate frequency signal (BS / CS-IF) in a predetermined frequency band (for example, 1032 to 2071 MHz) lower than the original frequency and is output (FIG. 5A). reference).

  Further, when receiving the DC 11V power supply from the communication device 70 side, the receiving unit 5b receives the left-handed circularly polarized wave in the transmission radio wave from the communication satellite (CS), and receives the received signal from the original frequency. Down-converted to an intermediate frequency signal (BS / CS-IF) of a lower predetermined frequency band (for example, 1595 to 2071 MHz) (see FIG. 5B).

  Then, the communication device 70 converts the reception signal (BS / CS-IF) input from the reception unit 5b and communication data (downlink data: 2650 to 3400 MHz) input via the HUB 6 into 59 GHz. Up-converted to the millimeter wave band with the first local oscillation signal f1c and transmitted to the communication device 80 on the mobile unit side (see FIG. 5).

  In addition, the mobile-side communication device 80 up-converts communication data (uplink data: 1032 to 2071 MHz) output from the information terminal 7 to the millimeter wave band using a transmission local oscillation signal f2o of 63.35 GHz. To the communication device 70 on the side (see FIG. 5).

  The communication devices 70 and 80 basically have the same circuit blocks as the communication devices 10 and 30 shown in FIG. 1, although the oscillation frequency of the local oscillator and the band of signals to be transmitted and received are different. Differences from the communication devices 10 and 30 shown in FIG.

  That is, as shown in FIG. 4, the communication device 70 on the base station side mixes the reception signal (BS / CS-IF) from the BS / CS antenna 5 and the uplink data (transmission data Tx) input from the HUB 6. A mixer 75 that outputs these signals as transmission signals to the mixer 23, and a power supply circuit 72 and a power supply filter 73 for supplying power to the receiving unit 5 b of the BS / CS antenna 5 are provided.

  Then, the power supply circuit 72 sets the power supply voltage supplied to the receiving unit 5b of the BS / CS antenna 5 to 11V or 15V according to the polarization switching signal demodulated from the pilot signal (frequency, for example, 900 MHz) by the ASK demodulator 25. Switch.

  On the other hand, the mobile communication device 80 demultiplexes the received signal after the pilot signal is separated by the pilot separation circuit 38 into BS / CS-IF and downlink data, and converts the BS / CS-IF into BS / CS-BS. A demultiplexing circuit 81 for outputting to the tuner 8 and outputting downlink data to the information terminal 7 is provided.

  Further, since the BS / CS tuner 8 is configured to selectively output a DC voltage of 11V or 15V in order to switch the reception polarization plane in the reception unit 5b of the BS / CS antenna 5, the branching circuit 81 is provided. A DC separation circuit 82 that separates the DC signal component is provided in the transmission line from the BS to the CS / CS tuner 8, and the DC separation circuit 82 further determines whether the separated voltage is 11V or 15V. A determination circuit 83 is provided.

  The determination output of the voltage determination circuit 83 is input to the ASK modulator 47. The ASK modulator 47 amplitude-modulates the pilot signal with the polarization switching signal corresponding to the determination result by the voltage determination circuit 83, and the information The data is transmitted to the base station side communication device 70 together with the uplink data from the terminal 7.

  Therefore, in the communication system shown in FIGS. 3 and 4, not only can the communication quality be ensured by using the pilot signal, but also the received polarization plane of the BS / CS antenna 5 is switched by amplitude-modulating the pilot signal. Thus, the pilot signal can be effectively used as an information transmission medium.

  In the case of the present embodiment, since a 60 MHz band millimeter-wave oscillator is used as the local oscillator for up-conversion and down-conversion, the local frequency used in the first embodiment is increased as the oscillation frequency increases. Compared with the oscillator, the frequency drift of the oscillator itself is larger, but in the present invention, the frequency fluctuation of the pilot signal that occurs when the pilot signal is transmitted and received between the base station and the mobile station is detected on the base station side. Since the base station corrects the oscillation frequency of the local oscillator used for up-conversion and down-conversion so that the frequency fluctuation is eliminated, the frequency fluctuation of the transmission / reception signal caused by the frequency drift of the local oscillator can be absorbed. Therefore, according to the present embodiment, it is possible to improve the communication failure caused by the frequency drift of the millimeter wave oscillator provided as a local oscillator in each of the communication devices 70 and 80, and to exert the effect even when the moving body is stopped. it can.

It is explanatory drawing showing the structure of the base station of the radio | wireless communications system of 1st Embodiment, and a mobile station. It is explanatory drawing showing the structure of the frequency control part of 1st Embodiment. It is a block diagram showing schematic structure of the radio | wireless communications system of 2nd Embodiment. It is explanatory drawing showing the structure of the base station of the radio | wireless communications system of 2nd Embodiment, and a mobile station. It is explanatory drawing explaining the signal transmitted / received in the radio | wireless communications system of 2nd Embodiment.

Explanation of symbols

  2 ... Data management device, 4 ... Data communication terminal, 5 ... BS / CS antenna, 5a ... Reflector, 5b ... Reception unit, 6 ... HUB, 7 ... Information terminal, 8 ... BS / CS tuner, 10 ... Communication device, DESCRIPTION OF SYMBOLS 11 ... Antenna, 12 ... 1st local oscillator, 13 ... Mixer, 15 ... Amplifier, 16 ... Filter, 17 ... Amplifier, 18 ... 2nd local oscillator, 19 ... Mixer, 21 ... Local oscillator, 22 ... ASK modulator, 23 DESCRIPTION OF SYMBOLS ... Mixer, 24 ... Pilot separation circuit, 25 ... ASK demodulator, 26 ... Communication control part, 27 ... Frequency comparison part, 28 ... Frequency control part, 30 ... Communication apparatus, 31 ... Antenna, 32 ... Filter, 33 ... Amplifier 34 ... Receiving local oscillator, 35 ... Mixer, 37 ... Amplifier, 38 ... Pilot separation circuit, 41 ... Local oscillator for transmission, 42 ... Mixer, 44 ... Amplifier, 45 ... ASK demodulator, 4 ... Amplifier 47 ... ASK modulator 48 ... Mixer 49 ... Communication controller 51 ... Reference voltage source 54 ... Switch 56 ... Distributor 57 ... Adder circuit 60 ... Output circuit 61 ... Detector circuit 62 ... determination circuit, 70 ... communication device, 72 ... power supply circuit, 73 ... power supply filter, 75 ... mixer, 80 ... communication device, 81 ... demultiplexing circuit, 82 ... DC separation circuit, 83 ... voltage determination circuit.

Claims (7)

A wireless communication system comprising a base station and a mobile station capable of wireless communication with each other in both directions,
The base station up-converts a transmission signal to be transmitted to the mobile station and a pilot signal of a specific frequency using a first-station signal of a predetermined frequency, and sends the signal after the up-conversion to the mobile station. Transmit from the antenna as a transmission signal,
The mobile station receives a transmission signal from the base station via an antenna, and down-converts the reception signal using a reception local oscillation signal whose frequency is fixed at substantially the same frequency as the first local oscillation signal. Then, the pilot signal is extracted from the down-converted received signal, the received signal after the pilot signal extraction is captured as a transmission signal from the base station, and the extracted pilot signal and the base station are The transmission signal to be transmitted is up-converted using a transmitting station-generated signal whose frequency is fixed, and the signal after the up-conversion is transmitted from the antenna as a transmission signal to the base station,
Further, the base station receives a transmission signal from the mobile station via an antenna, down-converts the reception signal using a second local oscillation signal having substantially the same frequency as the local transmission signal, The pilot signal is extracted from the down-converted received signal, the received signal after the pilot signal extraction is taken in as a transmission signal from the mobile station, and the extracted pilot signal and a pilot to be transmitted to the mobile station A radio communication system characterized in that the frequency of the first local oscillator signal and the second local oscillator signal are corrected by the same frequency so that the frequencies of the pilot signals coincide with each other by comparing the frequencies with the signals. . At the time of wireless communication with the mobile station, the base station gives the pilot signal identification information of the mobile station to be communicated by amplitude-modulating the pilot signal with the identification information of the mobile station to be communicated And
The mobile station demodulates the identification information from a pilot signal extracted from the down-converted received signal, and when the demodulated identification information is its own identification information, the received signal after the pilot signal extraction 2. The wireless communication system according to claim 1, wherein a receiving operation for capturing a signal as a transmission signal from the base station and a transmission operation for transmitting a transmission signal to the base station are performed. At the time of wireless communication with the base station, the mobile station gives its own identification information to the pilot signal by amplitude-modulating the pilot signal to be transmitted to the base station with its own identification information,
2. The base station demodulates the identification information from a pilot signal extracted from the down-converted received signal, and recognizes a mobile station as a communication partner from the demodulated identification information. Or the radio | wireless communications system of Claim 2. The base station
A satellite antenna that selectively receives one of two types of radio waves transmitted from a communication satellite and has a different polarization plane, converts the frequency into a broadcast signal of a predetermined frequency band, and outputs the broadcast signal;
The broadcast signal from the satellite antenna is configured to be up-converted with the transmission signal and the pilot and transmitted to a specific mobile station,
The mobile station assigns the pilot plane designation information to the pilot signal by amplitude-modulating the pilot signal to be transmitted to the base station with information designating the polarization plane of the radio wave received by the satellite antenna,
The base station demodulates the polarization plane designation information from the pilot signal extracted from the down-converted received signal, and switches the polarization plane of the radio wave received by the satellite antenna according to the demodulated designation information. The wireless communication system according to claim 1. A wireless communication device used as a base station for performing wireless communication with a mobile station,
An antenna for wireless communication;
Pilot signal generating means for generating a pilot signal of a specific frequency;
First local oscillation means for generating a first local oscillation signal having a predetermined frequency necessary for up-converting a transmission signal to be transmitted to the mobile station;
Second local oscillating means for generating a second local oscillation signal having a predetermined frequency necessary for down-converting a transmission signal from the mobile station;
A pilot signal from the pilot signal generating means and a transmission signal to be transmitted to the mobile station are mixed, up-converted using the first local signal generated by the first local oscillating means, and after the up-conversion First frequency converting means for transmitting the signal from the antenna as a transmission signal to the mobile station;
Second frequency converting means for down-converting the received signal from the antenna using the second local oscillation signal generated by the second local oscillation means;
Pilot signal extraction means for extracting a pilot signal from the reception signal down-converted by the second frequency conversion means and outputting the received signal after extraction of the pilot signal to an internal circuit as a transmission signal from a mobile station;
The pilot signal extracted by the pilot signal extracting means and the pilot signal generated by the pilot signal generating means are compared in frequency, and the first local oscillating means and the first oscillator Two local oscillation frequency correction means for correcting the oscillation frequency of the two local oscillation means by the same frequency;
A wireless communication apparatus comprising: A wireless communication device mounted on a mobile body and used as a mobile station that performs wireless communication with a base station,
An antenna for wireless communication;
Transmitting local oscillation means for generating a transmitting local oscillation signal having a constant frequency necessary for up-converting a transmission signal to be transmitted to the base station;
Receiving local oscillation means for generating a receiving local oscillation signal having a constant frequency necessary for down-converting a transmission signal from the base station;
A reception frequency converting means for down-converting a reception signal from the antenna using a reception local oscillation signal generated by the reception local oscillation means;
Pilot signal extraction means for extracting a pilot signal from the reception signal down-converted by the reception frequency conversion means, and outputting the received signal after extraction of the pilot signal to an internal circuit as a transmission signal from a base station;
The pilot signal extracted by the pilot signal extraction unit and the transmission signal to be transmitted to the base station are mixed, up-converted using the transmission local oscillation signal generated by the transmission local oscillation unit, and A transmission frequency converting means for transmitting the signal after up-conversion from the antenna as a transmission signal to the base station;
A wireless communication apparatus comprising: Modulation means for amplitude-modulating a pilot signal to be up-converted with the transmission signal;
Demodulation means for demodulating original information obtained by modulating the amplitude of the pilot signal from the pilot signal extracted by the pilot signal extraction means;
The wireless communication apparatus according to claim 5, comprising at least one of the following.

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