JP2009005279A - In-vehicle wireless communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-vehicle wireless communication apparatus capable of increasing the amount of data that can be transmitted/received, by efficiently selecting a base station to communicate with. <P>SOLUTION: An IF signal passed through an HPF 20 for cutting a DC component of an intermediate frequency is sampled by a second ADC 21 at a frequency lower than a double frequency of the IF signal. Channel information of a signal being transmitted from a base station is then acquired from output of the second ADC 21 by a communication channel information acquiring section 22, a transmission signal from the base station is received and during frequency selection for selecting a channel frequency to perform radio communication, a frequency of a local oscillator 19 is set in such a way as to dispose all the channels for receiving data from the base station. Furthermore, while using the information acquired by the communication channel information acquiring section 22, a channel to be connected by a channel selecting section 23 is determined. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle wireless communication apparatus, and is particularly suitable for application to a narrow-area communication system.

In recent years, ITS (Intelligent Transport System) has been installed on the base station (roadside) using the DSRC (Dedicated Short-Range Communication System) communication system including ETC (Non-stop automatic toll payment system). A system for performing wireless communication between a wireless device and a mobile station (a wireless device mounted on a vehicle) has been put into practical use.
Most of the services using the DSRC communication system that are currently in widespread use are used for ETC, but in recent years, the development of communication standards and laws concerning DSRC has progressed, and various services are expected to be realized in the future. Various services using DSRC, such as payments at parking lots and gas stations, information connection services in SA / PA (Service Area / Parking Area), and information provision on roads, are possible.
DSRC uses a frequency band of 5.8 GHz, and a communicable range is about several m to 30 m. In addition to the 1 Mbps using the ASK modulation method also used in the ETC, two transmission rates of 4 Mbps using the π / 4 shift QPSK modulation method are defined as the transmission rate. A DSRC mobile station receives FCMC (Frame Control Message Channel) including slot allocation information and frame control transmitted from a base station, and determines a frequency used for wireless communication. In DSRC, there are some communication devices that use only the ASK modulation method, such as ETC, depending on the application. Therefore, to ensure compatibility, FCMC uses the ASK modulation method. If selection is possible, π / 4 shift QPSK modulation is used for message data. A scheme can also be used.

FIG. 7 is a diagram showing the arrangement of radio frequencies and channels in ARIB STD-T75, which is a standard for narrow area communication systems.
In the ARIB STD-T75 standard, 7 channels are allocated for each of the uplink and the downlink, and the uplink frequency and the downlink frequency are paired. As is apparent from the channel arrangement in FIG. 7, channels that are 40 MHz apart are used in the uplink and the downlink. That is, the transmission signal from the base station is set to a maximum of 7 channels from 5.775 GHz to 5.805 GHz and is received by the mobile station.
In DSRC, since communication is performed between a base station installed on the roadside and a mobile station mounted on a vehicle that moves at high speed, the time during which data can be transmitted and received is very short. Therefore, it is desirable to finish the connection process with the base station in as short a time as possible. In order to connect a mobile station with a base station, it is necessary to first search for a connectable channel while traveling.

As described above, the base station is searched in order from the downlink channels that exist in the seven channels. At this time, the FCMC from the base station is received, the CRC test is performed, and the frequency can be selected when the CRC test result is normal. It is considered desirable for the mobile station to select the frequency after performing the FCMC CRC test a plurality of times for each channel.
Furthermore, if the FCMC CRC test result is normal for two or more channels, it is desirable to select the frequency by comparing the received power for each channel. The standard defines a frequency selection time, and the frequency selection is performed for each channel within a maximum of 9 slots of frames within 9 frames. In other words, a maximum of 63 msec time is required per channel, and if all channels are in use and can be received, search all channels and select a channel with good reception status and maximum power. A maximum of 441 msec is required. In the case of a vehicle that is traveling at a speed of 120 km / h, it will travel about 15 m. Thus, spending a lot of time in selecting a connection channel that can communicate reduces the time during which data can be transmitted and received, and reduces the amount of data that can be transmitted and received.

By the way, various types of RF configurations of the receiver are conceivable, and in general, a superheterodyne system, a direct conversion system, a LOW-IF system, or the like is adopted. Various RF configurations are also conceivable in the ARIB STD-T75 standard system.
FIG. 8 is a diagram showing an example of an RF configuration of a conventional receiving system.
The receiver in FIG. 8 includes an antenna 50 that receives a high-frequency signal, a band-limiting filter (first BPF) 51 that limits the band using all reception channels that use an input signal from the antenna 50, and a first BPF 51. A low-noise amplifier (LNA) 52 that amplifies the output signal of the LNA 52, a mixer (Mix) 53 for converting the output of the LNA 52 to an intermediate frequency, a variable local oscillator 59 that determines the mixing frequency of the mixer 53, and a mixer The IFAMP 54 that amplifies the intermediate frequency (IF) band signal that is the output of 53, the intermediate frequency band limiting filter (second BPF) 55 for band limiting the output of the IFAMP 54, and the output of the second BPF 55 are sampled. An AD converter (ADC) 56 for converting the digital data into digital data, and the digital data converted by the ADC 56 A demodulator 57 for demodulating a signal from, and a controller unit 58 for controlling the oscillation frequency of the local oscillator.

In the receiver configured as described above, if undersampling is performed, the sampling frequency of the ADC 56 can be lowered, so that the operating frequency of the demodulation processing by digital signal processing can be lowered, and the power consumption of the receiver can be reduced. There is a merit that it can be realized.
As described above, in the ARIB STD-T75 standard system, the transmitter and receiver channels are 40 MHz apart. Therefore, if the RF frequency conversion for reception is mixed with a local oscillator having the same frequency as the transmission channel, 40 MHz is received as the received IF signal. A centered signal is obtained. In this way, the received RF signal is down-converted to an IF signal of 40 MHz and can be demodulated, so that there is an advantage that a local oscillator can be realized by transmission and reception as described above.
FIG. 9 shows the relationship between the received signal and undersampling.
As shown in FIG. 9, a 40 MHz reception signal when the sampling frequency is operated at 32.768 MHz appears in a reception band centered on 7.232 MHz.

FIG. 10 is a diagram showing the relationship between the received signal from the base station connected at channel 7 (received at 5.775 GHz), the IF frequency of other channels, and the aliasing frequency when the sampling frequency is 32.768 MHz. In the undersampling method, since it overlaps in a half band of the sampling frequency, it is easily affected by other channel signals other than the received signal band.
FIG. 11 is a diagram showing the IF frequency and the aliasing frequency when the sampling frequency is 32.768 MHz and the channel 7 is connected, as in FIG.
In the conventional wireless communication apparatus, as shown in FIG. 11A, the band other than the received signal is sufficiently cut by the band limiting filter (BPF). This is very effective for preventing a communication error due to the occurrence of an interfering wave when message data is transmitted / received after selection of a communicable frequency is completed and the base station is connected.
However, since the band other than the received signal is cut, only communication information on one channel can be obtained with one frequency setting. That is, if the reception band is widened as shown in FIG. 11B and communication information on a plurality of channels is acquired with a single frequency setting, the frequency selection time for communication can be shortened.
Furthermore, DSRC can transmit using the ASK modulation method, and FCMC can use the ASK modulation method even in the case of using the π / 4 shift QPSK modulation method for data in order to ensure compatibility. Since the ASK modulation method conveys information by amplitude, it can be demodulated even if the intermediate frequency of the transmitter and the receiver do not match.

FIG. 12 is a diagram showing the relationship between the received signal, the IF frequency of other channels, and the aliasing frequency when the sampling frequency is 32.768 MHz and the center frequency is set for channel 1 (received at 5.795 GHz).
When the sampling frequency is 32.768 MHz, the signal of channel 6 (5.780 GHz) appears as a signal centered on 7.768 MHz. Since the original reception signal (5.795 GHz) appears in the reception band centered on 7.232 MHz, the channel 6 signal that becomes an interference wave is separated from the center frequency of the desired wave by only 0.536 MHz. Therefore, if the desired wave is not output at the same time in the receiver, the channel 6 that becomes a jamming wave is generally provided in the demodulator even if it passes through the LPF that cuts off the unwanted wave resulting from the jamming wave or down conversion. Can be demodulated without problems. Since the FCMC includes a code indicating the frequency with which the base station is communicating, if the CRC test result is normal, the radio frequency of the received channel can be specified.

Prior art patents such as Patent Documents 1 and 2 have been disclosed as methods for demodulating IF band signals by undersampling.
In Patent Document 1, a plurality of BPFs are used, and aliasing noise due to undersampling is cut. For this reason, as in a general wireless communication apparatus, only one channel communication status can be acquired with one frequency setting at the time of frequency selection, and a lot of time is devoted to the frequency selection time.
In Patent Document 2, the sampling frequency is changed according to the interference wave, the desired wave, and the received intensity. However, it is intended to prevent communication errors due to jamming waves, and detects the presence of jamming waves that affect the channel being received, but does not detect jamming waves or the communication status of channel frequencies other than the reception band. The frequency selection time is not taken into account until shortening.

JP 2003-318760 A JP 2004-96141 A

As described above, in-vehicle wireless communication devices are required to perform data transmission / reception in a short time, so it is desirable to perform a connection process in as short a time as possible. For this reason, it is desirable that selection of connection channels capable of communication is completed in a short time. On the other hand, in a receiver that performs reception processing using an undersampling technique, a phenomenon in which an interference wave is folded on a desired wave occurs. As a result, when selecting a frequency, a plurality of pieces of channel information can be acquired with a single frequency setting, leading to a reduction in frequency selection time.
In view of such a problem, the present invention provides a base station that efficiently communicates by using a signal of a channel other than the channel being received by receiving the signal by using an undersampling method in a mobile station of an in-vehicle communication device that moves at high speed. An object of the present invention is to provide an in-vehicle wireless communication device that can select a station and increase the amount of data that can be transmitted and received.

In order to solve the above-mentioned problem, the present invention according to claim 1 is an antenna for receiving a high-frequency signal composed of a plurality of adjacent channels, and restricts an input signal from the antenna by a use band of all reception channels. A first band limiting filter, an amplifier that amplifies the output signal of the first band limiting filter, a mixer that converts the output of the amplifier to an intermediate frequency, a local oscillator that determines a mixing frequency of the mixer, An intermediate frequency amplifier that amplifies an intermediate frequency signal that is an output of the mixer, a second band limiting filter that limits the output of the intermediate frequency amplifier, and an output of the second band limiting filter is digitally sampled. A first AD converter for converting data, a demodulator for demodulating the output of the first AD converter by digital signal processing, and the local oscillator In a vehicle-mounted wireless communication device comprising a controller unit that controls the oscillation frequency of the detector, a high-pass filter that cuts off the DC component of the intermediate frequency, and an intermediate frequency band signal that has passed through the high-pass filter, A second AD converter that samples at a frequency lower than twice the frequency of the frequency band signal, and a communication channel that acquires channel information of a transmission signal transmitted from the base station from the output of the second AD converter An information acquisition unit, and a channel selection unit that determines a channel to be connected using the information acquired by the communication channel information acquisition unit, and receives a transmission signal from the base station and sets a channel frequency for wireless communication. At the time of selecting a frequency to be selected, the controller unit is configured so that all channels for receiving data from the base station are arranged. Set the wave number, the communication channel information acquisition unit, characterized by sampling the digital data by the intermediate frequency and the second AD converter output of the amplifier.
According to the present invention, communication information of all channels can be acquired with a single frequency setting. Therefore, channel selection can be performed efficiently, and the time required for channel selection can be greatly shortened.

According to a second aspect of the present invention, there is provided an antenna for receiving a high-frequency signal composed of a plurality of adjacent channels, and a first band limiting filter for limiting an input signal from the antenna with a use band of all reception channels. An amplifier that amplifies the output signal of the first band limiting filter, a mixer that converts the output of the amplifier to an intermediate frequency, a local oscillator that determines a mixing frequency of the mixer, and an intermediate that is the output of the mixer An intermediate frequency amplifier for amplifying a frequency band signal; a second band limiting filter for band limiting the output of the intermediate frequency amplifier; and a first for sampling and converting the output of the second band limiting filter to digital data An AD converter, a demodulator that demodulates the output of the first AD converter by digital signal processing, and an oscillation frequency of the local oscillator are combined. In a vehicle-mounted wireless communication device including a controller unit that rolls, a high-pass filter that cuts off the DC component of the intermediate frequency, an output of the second band-limiting filter, and an output of the high-pass filter can be selected A filter selection unit, a communication channel information acquisition unit for acquiring channel information of a signal transmitted by the base station from an output of the first AD converter, and information acquired by the communication channel information acquisition unit A channel selection unit for determining a channel to be connected, and when receiving a transmission signal from the base station and selecting a channel frequency for performing wireless communication, the controller unit receives data from the base station. The frequency of the local oscillator is set so that all channels to be received are arranged, and the communication channel information acquisition unit is configured to use the first AD converter. The sampling frequency is set to a frequency lower than twice the frequency of the intermediate frequency band signal, the output of the high-pass filter is selected by the filter selection unit, and the high frequency band is selected by the first AD converter. The intermediate frequency band signal that has passed through the pass filter is sampled into a digital signal.
According to the present invention, since communication information of all channels can be acquired with one frequency setting, it is possible to perform channel selection efficiently, and the time required for channel selection can be greatly shortened. .

According to a third aspect of the present invention, there is provided an antenna for receiving a high-frequency signal composed of a plurality of adjacent channels, and a first band limiting filter for limiting an input signal from the antenna with a use band of all reception channels. An amplifier that amplifies the output signal of the band limiting filter, a mixer that converts the output of the amplifier to an intermediate frequency, a local oscillator that determines a mixing frequency of the mixer, and an intermediate frequency band signal that is the output of the mixer An intermediate frequency amplifier for amplifying the output, a second band limiting filter for band limiting the output of the intermediate frequency amplifier, and a first AD converter for sampling the output of the second band limiting filter and converting it into digital data A demodulator for demodulating the output of the first AD converter by digital signal processing, and controlling the oscillation frequency of the local oscillator A communication channel information acquisition unit that acquires channel information of a signal transmitted by the base station from an output of the first AD converter; and the communication channel information acquisition A channel selection unit that determines a channel to be connected using information acquired by the unit, receiving a transmission signal from the base station, and selecting a channel frequency for performing wireless communication, the controller unit, The frequency of the local oscillator is set so that two or more channels for receiving data from a base station are arranged, and the communication channel information acquisition unit sets the sampling frequency of the first AD converter to the intermediate frequency The intermediate frequency band signal that has passed through the second band limiting filter is set to a frequency lower than twice the frequency of the frequency band signal. Characterized by sampling the digital signal by the AD converter.
According to the present invention, communication information of two or more channels can be acquired with one frequency setting. Therefore, channel selection can be performed efficiently, and the time required for channel selection can be shortened.

Further, in the present invention according to claim 4, the communication channel information acquisition unit transmits the base station using a code indicating which frequency the base station is communicating by demodulating the received frame. The in-vehicle wireless communication apparatus according to any one of claims 1 to 3, wherein channel information of a received signal is obtained.
According to the present invention, channel information transmitted by the base station from the FCMC can be obtained from the FCMC when the FCSK of the ASK modulation scheme is received and the CRC test result is normal even in channels other than the reception channel. Therefore, it is possible to reliably obtain channel information of the frequency at which the base station is transmitting.
Further, in the present invention according to claim 5, the communication channel information acquisition unit performs frequency analysis by FFT calculation, calculates a power value of each channel frequency of the received channel signal, and transmits a signal transmitted from the base station. The in-vehicle wireless communication apparatus according to any one of claims 1 to 3, wherein channel information is obtained.
According to the present invention, communication information of each channel can be acquired even if an interference wave is generated and the interference wave is turned back to the reception band of the desired wave due to undersampling and a communication error occurs. Therefore, the time required for channel selection can be shortened.
Further, in the present invention according to claim 6, the communication channel information acquisition unit arranges, in parallel, a group of filters that pass a signal of a bandwidth for receiving one or more channels with the frequency of each reception channel as a center frequency. 4. The in-vehicle wireless communication device according to claim 1, wherein the power value of each output from the filter group is calculated to obtain channel information of a signal transmitted by a base station. 5. And
According to the present invention, communication information of each channel can be acquired even if an interference wave is generated and the interference wave is turned back to the reception band of the desired wave due to undersampling and a communication error occurs. Therefore, the time required for channel selection can be shortened.

  According to the present invention, in a mobile station receiver of an in-vehicle wireless communication device, reception processing is performed by an undersampling method when selecting a frequency, and communication information of a plurality of channels is acquired by one frequency setting, thereby shortening connection processing. By carrying out in time, the mobile station of the vehicle-mounted radio | wireless communication apparatus which can transmit / receive a lot of data can be provided.

Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 is a block diagram of a radio reception apparatus according to the first embodiment of the present invention. The radio receiver 1 shown in FIG. 1 includes an antenna 10 that receives a high-frequency signal, and a band limiting filter (first band limiting filter; (Referred to as a first BPF) 11, a low noise amplifier (LNA) 12 that amplifies the output signal of the first BPF 11, and a mixer (Mix) 13 that converts the output of the LNA 12 into an intermediate frequency. A local oscillator 19 is connected to the mixer 13 to determine a mixing frequency. The output of the mixer 13 includes an IF amplifier (IF amplifier) 14 that amplifies an intermediate frequency (IF) band signal, and an intermediate frequency band limiting filter (second band limiting filter, hereinafter referred to as a first band limiting filter) that limits the output of the IF amplifier 14. 2) 15, the first AD converter (first ADC) 16 that samples and converts the output of the second BPF 15 into digital data, and the digital data converted by the first ADC 16 A demodulator 17 and a controller 18 for demodulating the signal are provided.

Furthermore, in the radio receiving apparatus according to the present embodiment, the high-pass filter (HPF) 20 that cuts the DC component of the output of the IF amplifier 14 and passes only the high-frequency component, and the output of the HPF 20 are sampled to obtain digital data. A second AD converter (second ADC) 21 that converts the communication channel information, a communication channel information acquisition unit 22 that acquires communication channel information from the digital data converted by the second ADC 21, and the communication channel information acquisition unit And a channel selection unit 23 that determines a channel to be connected using the information acquired in 22.
The sampling frequency of the first ADC 16 may be set to a frequency lower than twice the reception IF frequency, and reception processing may be performed using an undersampling method, or the Nyquist condition of at least twice the reception IF frequency is satisfied. The reception processing may be performed using an oversampling method. You may select and use a system with good reception status. The reception processing is performed with the band-limited signal using only the first ADC 16 after the channel to be used is determined.
In general, since the channel number used by the base station is not known, it is possible to detect the channel used by the base station first, perform connection processing thereafter, and start data communication after connection. Therefore, it is necessary to always be in a channel detection state while traveling.
If the channel detection processing is performed by changing the frequency of the local oscillator for each channel as in the above-described conventional technology, the detection processing for 7 channels may require 441 msec.

Therefore, in the present embodiment, the second ADC 21 is used instead of the first ADC 16 during channel selection. The sampling frequency of the second ADC 21 is set to a frequency lower than twice the reception IF frequency, and reception processing is performed using an undersampling method. Then, the frequency at which the signal from the base station is transmitted is detected by demodulating the digital signal sampled by the second ADC 21 and detecting the power.
That is, in the present embodiment, when selecting a frequency for receiving a transmission signal from the base station and selecting a channel frequency for performing wireless communication, the controller unit 18 is arranged so that all channels for receiving data from the base station are arranged. The frequency of the local oscillator 19 is set to, and the communication channel information acquisition unit 22 samples the output of the IF amplifier 14 into digital data by the second ADC 21.
Thereafter, based on the information obtained by the detection process, the controller unit 18 performs frequency setting, returns to normal reception, and analyzes the frame received by the first ADC 16. Of course, a channel for which communication information of the base station cannot be obtained from the FCMC, or a channel determined to have no power when selecting a frequency is excluded from reception. The power may be determined using a threshold value. By doing so, communication information of a plurality of channels can be obtained at a time, and thus the time required for frequency selection can be shortened.

FIG. 2 is a block diagram of a radio reception apparatus according to the second embodiment of the present invention.
The radio reception device 30 shown in FIG. 2 is provided with a selector (filter selection unit) 31 instead of using the second ADC 21 as in the radio reception device 1 shown in FIG. 1, and dynamically changes the sampling frequency of the first ADC 16. It can be realized by one ADC. This eliminates the need to install two ADCs, and is advantageous in terms of cost.
The basic operation procedure is the same as described above, but during channel selection, the signal path is switched by the selector 31 to use the DC cut HPF output signal as shown in FIG. 2, and at the same time the sampling of the first ADC 16 is performed. Change the frequency to a frequency lower than twice the IF signal. When the channel to be used is determined, the selector 31 switches the signal path so that the band-limited signal by the second BPF 15 is used.
At this time, the sampling frequency of the first ADC 16 may be set to a frequency lower than twice the reception IF frequency, and reception processing may be performed using an undersampling method, or Nyquist greater than or equal to twice the reception IF frequency. The frequency may be set to satisfy the condition, and the reception process may be performed using an oversampling method. Alternatively, a method with a good reception state may be selected and used. As a result, the power of all channels can be calculated, and the channel selection order can be determined as described above.

FIG. 3 is a block diagram of a radio reception apparatus according to the third embodiment of the present invention.
The wireless receiver 40 shown in FIG. 3 dynamically changes the sampling frequency of the first ADC 16 without using the HPF 20 provided in the wireless receivers 1 and 30 shown in FIGS. Communication information of two or more channels that can be acquired from the output of the second BPF 15 is acquired. This eliminates the need for mounting the HPF 20, which is advantageous in terms of cost. The basic operation procedure is the same as described above, but the sampling frequency of the first ADC 16 is changed to a frequency lower than twice the IF signal during frequency selection.
Since the signal whose band is limited by the second BPF 15 is used for frequency selection, it is difficult to perform detection processing for all channels with a single frequency setting. Therefore, it is necessary to perform detection processing by setting the frequency a plurality of times. In addition, since signals of two or more channels are output from the second BPF 15, it is possible to cut unnecessary band signals with a digital LPF or BPF or increase the sampling frequency at times other than when selecting a frequency. It is necessary to prevent the influence of jamming waves.

In the first to third embodiments, a method for acquiring channel information of a signal transmitted by the base station in the communication channel information acquiring unit 22 will be described.
First, a method for acquiring the first channel information will be described.
In this case, it is assumed that the mobile station of the in-vehicle wireless communication apparatus having the wireless reception apparatus shown in FIG. 1 performs frequency selection by setting the sampling frequency to 32.768 MHz and the frequency to channel 7. Of course, any channel may be used for frequency selection, and any frequency may be used as long as the sampling frequency can perform undersampling. The relationship between the received signal, the IF frequency of the other channel, and the aliasing frequency when the frequency (reception center frequency of the mobile station is 5.775 GHz) is set for the channel 7 is shown in FIG.

FIG. 4 shows the frame transmission status in each channel. The horizontal axis represents time, and the vertical axis represents channel number (radio frequency).
As shown in FIG. 4, when each frame is transmitted at different times and the frame is transmitted by ASK modulation used in a service such as ETC, the frequency of the mobile station is set to channel 7. Even if it is set, frames of all channels can be received. This is because the ASK modulation is a modulation method for transmitting information by changing the amplitude of the signal. Unlike the modulation method using the phase or frequency (for example, PSK modulation or FSK modulation), the received signal and the receiver channel This is because demodulation can be performed even if the numbers do not match.
In this way, the received frame is demodulated and CRC verification is performed. As described above, the frequency selection process may be performed by only one frequency setting, or may be performed by selecting a plurality of times if all the channels cannot be covered by one frequency setting.

In the frequency selection process, it is necessary to select which channel communicates with the base station. A conventional receiver receives only a frame of a frequency-set channel. Therefore, it is possible to immediately determine on which channel the frame being received is transmitted. However, in the frequency selection process performed by the mobile station of this embodiment, there is a possibility that frames of all channels can be received with one frequency setting, so the frame being received is a frame transmitted at which frequency. It cannot be determined immediately.
In the FCMC of ARIB STD-T75 standard, it is specified to include a frequency type identifier indicating which frequency the base station that transmitted the frame is operating.
Therefore, in the present embodiment, CRC verification is performed, and when the CRC verification result is normal, the frequency type identifier included in the frame is analyzed, channel information operated by the base station is acquired, and a plurality of base stations are detected. In such a case, the channel is shifted to a channel used by a base station with good power and reception.

Next, a method for acquiring the second channel information will be described.
In this case, the mobile station of the in-vehicle wireless communication apparatus having the wireless receiving apparatus shown in FIG. 1 performs frequency selection by setting the sampling frequency to 32.768 MHz and the frequency to channel 7.
FIG. 5 is a diagram showing the power spectrum of each channel obtained by the FFT operation. By performing the FFT operation in this way, it is possible to analyze which channel the base station is operating in, and it is not necessary to perform FCMC CRC verification on all channels.
Therefore, FFT calculation is performed, and only a channel for which a certain power has been confirmed by the analysis result is subjected to the FCMC CRC test again in the reception state with less communication error using the oversampling method, and the base station to be connected is selected. be able to.

Next, a method for acquiring third channel information will be described.
FIG. 6 is a diagram illustrating an example of a communication channel information acquisition unit.
As shown in FIG. 6, band limiting filters (BPF) 51-1 to 51-7 are prepared for each channel, and the power values of signals that have passed through the filter group are calculated by the power spectrum calculation units 52-1 to 52-7, respectively. Thus, it is possible to analyze which channel is used by the base station. Therefore, it is not necessary to perform FCMC CRC verification on all channels. Only the channel where the power value of the signal that has passed through the filter group exceeds a certain value can be subjected to FCMC CRC verification again in the reception state with less communication error using the oversampling method, and the base station to be connected can be selected. it can.

1 is a block diagram of a radio reception apparatus according to a first embodiment of the present invention. It is a block diagram of the radio | wireless receiver which concerns on the 2nd Embodiment of this invention. It is a block diagram of the radio | wireless receiver which concerns on the 3rd Embodiment of this invention. It is the figure which showed the transmission condition of the flame | frame in each channel. It is the figure which showed the power spectrum of each channel obtained by FFT calculation. It is the figure which showed an example of the communication channel information acquisition part. It is the figure which showed the arrangement | positioning of the radio frequency and each channel in ARIB STD-T75 which is a standard of a narrow region communication system. It is the figure which showed an example of the RF structure of the conventional receiving system. It is the figure which showed the relationship between a received signal and undersampling. It is the figure which showed the relationship between the received signal from the base station connected with the channel 7, the IF frequency of another channel, and the aliasing frequency when the sampling frequency is 32.768 MHz. It is a figure which shows the mode of IF frequency and a folding frequency when a sampling frequency is 32.768 MHz and it connects by the channel 7. FIG. It is the figure which showed the relationship between the received signal, the IF frequency of another channel, and the aliasing frequency when the sampling frequency is 32.768 MHz and the center frequency is set for channel 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 30, 40 ... Wireless receiver, 10 ... Antenna, 11 ... 1st BPF, 12 ... LNA, 13 ... Mixer, 14 ... IF amplifier, 15 ... 2nd BPF, 16 ... 1st ADC, 17 ... Demodulation unit, 18 ... controller unit, 19 ... local oscillator, 20 ... HPF, 21 ... second ADC, 22 ... communication channel information acquisition unit, 23 ... channel selection unit, 31 ... selector, 51-1 to 51-7 ... BPF, 52-1 to 52-7 ... Power spectrum calculator

Claims (6)

An antenna that receives a high-frequency signal composed of a plurality of adjacent channels, a first band-limiting filter that limits an input signal from the antenna with a use band of all reception channels, and an output of the first band-limiting filter An amplifier that amplifies the signal, a mixer that converts the output of the amplifier to an intermediate frequency, a local oscillator that determines a mixing frequency of the mixer, an intermediate frequency amplifier that amplifies an intermediate frequency signal that is the output of the mixer, A second band limiting filter for band limiting the output of the intermediate frequency amplifier; a first AD converter for sampling and converting the output of the second band limiting filter to digital data; and the first AD conversion. A demodulator for demodulating the output of the detector by digital signal processing, and a controller for controlling the oscillation frequency of the local oscillator In-vehicle radio communication device to obtain,
A high-pass filter for cutting the DC component of the intermediate frequency;
A second AD converter that samples the intermediate frequency band signal that has passed through the high-pass filter at a frequency lower than twice the frequency of the intermediate frequency band signal;
A communication channel information acquisition unit for acquiring channel information of a transmission signal transmitted by the base station from the output of the second AD converter;
A channel selection unit that determines a channel to be connected using the information acquired by the communication channel information acquisition unit,
When selecting a frequency for receiving a transmission signal from the base station and selecting a channel frequency for performing wireless communication, the controller unit is configured so that all channels for receiving data from the base station are arranged. An in-vehicle wireless communication apparatus, wherein a frequency is set, and the communication channel information acquisition unit samples the output of the intermediate frequency amplifier into digital data by the second AD converter. An antenna that receives a high-frequency signal composed of a plurality of adjacent channels, a first band-limiting filter that limits an input signal from the antenna with a use band of all reception channels, and an output of the first band-limiting filter An amplifier that amplifies the signal, a mixer that converts the output of the amplifier to an intermediate frequency, a local oscillator that determines a mixing frequency of the mixer, an intermediate frequency amplifier that amplifies an intermediate frequency signal that is the output of the mixer, A second band limiting filter for band limiting the output of the intermediate frequency amplifier; a first AD converter for sampling and converting the output of the second band limiting filter to digital data; and the first AD conversion. A demodulator for demodulating the output of the detector by digital signal processing, and a controller for controlling the oscillation frequency of the local oscillator In-vehicle radio communication device to obtain,
A high-pass filter for cutting the DC component of the intermediate frequency;
A filter selection unit capable of selecting an output of the second band-limiting filter and an output of the high-pass filter;
A communication channel information acquisition unit for acquiring channel information of a signal transmitted by the base station from an output of the first AD converter;
A channel selection unit that determines a channel to be connected using the information acquired by the communication channel information acquisition unit,
When selecting a frequency for receiving a transmission signal from a base station and selecting a channel frequency for wireless communication, the controller unit sets the frequency of the local oscillator so that all channels for receiving data from the base station are arranged. And the communication channel information acquisition unit sets the sampling frequency of the first AD converter to a frequency lower than twice the frequency of the intermediate frequency band signal, and then the high frequency is selected by the filter selection unit. An in-vehicle wireless communication apparatus, wherein an output of a band-pass filter is selected, and an intermediate frequency band signal that has passed through the high-pass filter in the first AD converter is sampled into a digital signal. An antenna that receives a high-frequency signal composed of a plurality of adjacent channels, a first band-limiting filter that limits an input signal from the antenna with a use band of all reception channels, and an output signal of the band-limiting filter An amplifier that converts the output of the amplifier to an intermediate frequency, a local oscillator that determines a mixing frequency of the mixer, an intermediate frequency amplifier that amplifies an intermediate frequency band signal that is the output of the mixer, and the intermediate frequency A second band-limiting filter that band-limits the output of the amplifier; a first AD converter that samples and converts the output of the second band-limiting filter into digital data; and an output of the first AD converter A demodulator for demodulating the signal by digital signal processing, and a controller for controlling the oscillation frequency of the local oscillator In the wireless communication device for mounting,
A communication channel information acquisition unit for acquiring channel information of a signal transmitted by the base station from an output of the first AD converter;
A channel selection unit that determines a channel to be connected using the information acquired by the communication channel information acquisition unit,
The controller unit receives the transmission signal from the base station and selects a channel frequency for wireless communication. The controller unit includes the local oscillator so that two or more channels for receiving data from the base station are arranged. The communication channel information acquisition unit sets the sampling frequency of the first AD converter to a frequency lower than twice the frequency of the intermediate frequency band signal, and then sets the second frequency. An in-vehicle wireless communication apparatus characterized in that an intermediate frequency band signal that has passed through a band limiting filter is sampled into a digital signal by the first AD converter.   The communication channel information acquisition unit obtains channel information of a signal transmitted by the base station from a code indicating at which frequency the base station is communicating by demodulating the received frame. The in-vehicle wireless communication device according to any one of claims 1 to 3.   The communication channel information acquisition unit performs frequency analysis by FFT calculation, calculates a power value of each channel frequency of a reception channel signal, and obtains channel information of a signal transmitted from a base station. The in-vehicle wireless communication device according to any one of 1 to 3.   The communication channel information acquisition unit arranges, in parallel, a filter group that passes a signal of a bandwidth for receiving one or more channels with the frequency of each reception channel as a center frequency, and outputs each output from the filter group. The in-vehicle wireless communication apparatus according to any one of claims 1 to 3, wherein a power value is calculated to obtain channel information of a signal transmitted from the base station.

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