WO2018207499A1

WO2018207499A1 - Wireless communication device and wireless communication method

Info

Publication number: WO2018207499A1
Application number: PCT/JP2018/014085
Authority: WO
Inventors: 藤田　浩章; 佐生　登; 史隆近藤; 山本　憲; 田村　昌久; 喜久高池
Original assignee: ソニーセミコンダクタソリューションズ株式会社
Priority date: 2017-05-08
Filing date: 2018-04-02
Publication date: 2018-11-15
Also published as: JPWO2018207499A1; JP7179720B2

Abstract

The wireless communication device relating to one embodiment of the present technology is provided with a communication unit, conversion unit, generation unit, and supply unit. The communication unit is capable of transmitting/receiving electromagnetic waves for narrow band communication. On the basis of a first reference signal, the conversion unit converts the frequency of a reception signal into an intermediate frequency, said reception signal having been generated corresponding to reception of the electromagnetic waves for the narrow band communication. On the basis of a second reference signal having a frequency different from that of the first reference signal, the generation unit generates a transmission signal to be used for transmission of the electromagnetic waves for the narrow band communication. The supply unit is capable of performing switching between operation of supplying the first reference signal to the conversion unit, and operation of supplying the second reference signal to the generation unit.

Description

Wireless communication apparatus and wireless communication method

The present technology relates to a wireless communication apparatus and a wireless communication method used for narrow area communication.

Patent Document 1 describes an in-vehicle wireless communication device using a narrow range communication (DSRC: Dedicated Short Range Communication) system. In the in-vehicle wireless communication device, a high frequency signal transmitted from a base station installed on the roadside is received. The received high-frequency signal is converted to an intermediate frequency based on a mixing frequency oscillated by a local oscillator (LO: Local Oscillator), and digital data or the like is read out. (Patent Document 1, specification paragraphs [0002] [0003] [0017] [0019] FIG. 1 etc.).

JP 2009-5279 A

Various systems using such narrow area communication have been developed, and a technology for realizing miniaturization of a wireless communication apparatus is required.

In view of the circumstances as described above, an object of the present technology is to provide a wireless communication device and a wireless communication method for narrow area communication that can realize downsizing of the device.

In order to achieve the above object, a wireless communication apparatus according to an embodiment of the present technology includes a communication unit, a conversion unit, a generation unit, and a supply unit.
The communication unit can transmit and receive radio waves for narrow area communication.
The conversion unit converts a reception signal generated in response to reception of the radio wave for narrow-area communication into an intermediate frequency based on a first reference signal.
The generation unit generates a transmission signal used for transmission of the radio wave for the narrow area communication based on a second reference signal having a frequency different from that of the first reference signal.
The supply unit can switch between supply of the first reference signal to the conversion unit and supply of the second reference signal to the generation unit.

In this wireless communication device, the first and second reference signals having different frequencies are appropriately switched and supplied to the conversion unit and the generation unit. As a result, for example, the intermediate frequency can be controlled, and data can be received without using an external filter or the like. As a result, it is possible to reduce the size of the wireless communication device.

The conversion unit may convert the received signal into the intermediate frequency by mixing the first reference signal and the received signal. In this case, the supply unit may control the frequency of the first reference signal so that the intermediate frequency is smaller than a frequency difference between the reception signal and the transmission signal.
Filtering is facilitated by reducing the value of the intermediate frequency. As a result, an external filter or the like is not necessary, and the apparatus can be miniaturized.

The conversion unit may include a first internal filter that allows a frequency component of a first band including the intermediate frequency to pass therethrough and restricts a frequency component not included in the first band.
Thereby, for example, filtering by a band-pass filter configured in the integrated circuit becomes possible. As a result, the apparatus can be sufficiently downsized.

The intermediate frequency may have an absolute value of 2.2 MHz or more and 2.8 MHz or less.
As a result, it is possible to suppress a signal of a narrow-band communication channel other than the target channel from becoming an interference wave, and it is possible to improve communication accuracy.

The intermediate frequency may have an absolute value of approximately 2.5 MHz.
This makes it possible to sufficiently cut off extra signals such as jamming waves and sufficiently improve communication accuracy.

The supply unit may control the frequency of the first reference signal so that the intermediate frequency becomes substantially zero.
Thereby, for example, data included in the first high-frequency signal can be directly demodulated. As a result, the apparatus configuration becomes simple and the apparatus can be miniaturized.

The conversion unit may include a second internal filter that passes a frequency component of a second band including the intermediate frequency and restricts a frequency component higher than an upper limit frequency of the second band.
Thereby, for example, filtering by a low-pass filter configured in the integrated circuit becomes possible. As a result, the apparatus can be sufficiently downsized.

The supply unit may include a phase synchronization circuit that can oscillate by switching the first and second reference signals.
As a result, the first and second reference signals can be generated with high accuracy, and the operation accuracy can be improved.

The supply unit may include a frequency division unit that divides the frequency of the second reference signal at a predetermined ratio to generate a frequency division signal. In this case, the generation unit may generate the transmission signal by executing mixing of the divided signal and mixing of the second reference signal with respect to the baseband signal.
Thereby, the frequency of the 2nd high frequency signal transmitted differs from the frequency of the 2nd reference signal. As a result, it is possible to suppress problems due to frequency coupling.

The predetermined ratio may be any one of 1/2, 1/4, and 1/6.
For example, the frequency can be easily divided using a frequency divider or the like. This makes it possible to provide a device that has a simple configuration and is resistant to coupling and the like.

The wireless communication apparatus may further include a signal generation unit that generates a data signal based on the intermediate frequency signal.
As a result, for example, a data signal can be generated in accordance with a subsequent circuit for performing data processing or the like, and high versatility is exhibited.

The data signal may include at least one of a QPSK signal, an ASK signal, and a carrier strength signal.
Thereby, it becomes possible to cope with various communication methods used in narrow area communication.

The signal generation unit may include a digital filter unit that digitizes and filters the signal of the intermediate frequency, and a mixer unit that converts the output of the digital filter unit into a frequency for demodulation.
As a result, the data signal can be demodulated based on the signal filtered in the digital domain, and the communication accuracy can be greatly improved.

The digital filter unit and the mixer unit may operate based on a reference clock signal.
By using the reference clock signal, for example, a dedicated clock circuit or the like becomes unnecessary, and the apparatus can be miniaturized.

The reception signal may be a signal having a frequency lower than that of the transmission signal.
This makes it possible to provide a wireless communication device that functions as a mobile station that performs communication while moving.

The wireless communication device may be configured as a vehicle-mounted device.
Thereby, it is possible to provide a small vehicle-mounted device capable of narrow-area communication.

A wireless communication method according to an aspect of the present technology includes transmitting and receiving radio waves for narrow area communication.
Based on the first reference signal, a reception signal generated in response to reception of the radio wave for narrow area communication is converted into an intermediate frequency.
Based on a second reference signal having a frequency different from that of the first reference signal, a transmission signal used to transmit the radio wave for narrow area communication is generated.
The supply of the first reference signal and the supply of the second reference signal are switched.

As described above, according to the present technology, it is possible to reduce the size of a wireless communication device for narrow area communication. Note that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

It is a mimetic diagram showing an example of composition of a radio communications apparatus concerning a 1st embodiment of this art. It is a figure which shows typically the relationship of the channel used for DSRC system communication. It is a schematic diagram which shows the frequency relationship of a channel. It is a schematic diagram which shows an example of the conversion to the intermediate frequency by an orthogonal mixer. It is a schematic diagram which shows the other structural example of the radio | wireless communication apparatus which concerns on 1st Embodiment. It is a schematic diagram which shows the structural example of the radio | wireless communication apparatus mention | raise | lifted as a comparative example. It is a schematic diagram which shows the structural example of the radio | wireless communication apparatus which concerns on 2nd Embodiment. It is a schematic diagram which shows the structural example of the radio | wireless communication apparatus which concerns on 3rd Embodiment.

Hereinafter, embodiments of the present technology will be described with reference to the drawings.

<First Embodiment>
[Configuration of wireless communication device]
FIG. 1 is a schematic diagram illustrating a configuration example of a wireless communication device according to the first embodiment of the present technology. The wireless communication device 100 is configured as an in-vehicle device capable of communication in a narrow area communication method (DSRC method), and is used for communication with a base station or the like installed on a roadside or the like.

By mounting the wireless communication device 100 on a vehicle such as an automobile, it is possible to pay tolls using the ETC (Electronic Toll Collection System) (registered trademark) service and to acquire traffic information using the ETC 2.0 service. It becomes.

As shown in FIG. 1, the wireless communication device 100 includes a communication unit 10, a reception unit 20, a transmission unit 30, and a local oscillator (LO: Local Oscillator) 40. Further, the wireless communication device 100 has a controller (not shown).

The communication unit 10 includes an antenna 11, a band pass filter (BPF) 12, and a switch element 13.

The antenna 11 can transmit and receive radio waves in the frequency band (5.8 GHz band) used in the DSRC method. The antenna 11 outputs an electric signal having the same frequency as the received radio wave, and radiates a radio wave having the same frequency as the input electric signal. For example, as the antenna 11, a pattern antenna formed on a substrate, a chip antenna that can be mounted on the substrate, or the like is used. The specific configuration of the other antenna 11 is not limited, and any antenna may be used.

The band pass filter 12 passes the frequency components of the frequency band used in the DSRC method among the frequency components of the electric signal input to the band pass filter 12. The band pass filter 12 regulates frequency components in other bands different from the frequency band used in the DSRC method. The specific configuration of the bandpass filter 12 is not limited, and an arbitrary filter may be used.

The switch element 13 switches the output destination of the input electrical signal based on the control signal output from the controller. The specific configuration of the switch element 13 is not limited, and for example, any element that can be connected by switching circuits may be used.

When communication (downlink communication) from the base station or the like to the vehicle-mounted device is performed, the antenna 11 receives a radio wave having a first frequency corresponding to the DSRC method transmitted from the base station or the like. An electrical signal corresponding to the received radio wave is output to the band pass filter 12 and filtered. As a result, the first high-frequency signal 51 having the first frequency is output to the switch element 13. The first high frequency signal 51 is output to the receiving unit 20 via the switch element 13.

When communication (uplink communication) from the vehicle-mounted device to the base station or the like is performed, a second high-frequency signal 52 having a second frequency corresponding to the DSRC method is generated by the transmission unit 30 as described later. The second high frequency signal 52 is output to the band pass filter 12 via the switch element 13. A radio wave having a second frequency is transmitted from the antenna 11 based on the second high-frequency signal 52 filtered by the bandpass filter 12.

By using the switch element 13, transmission and reception can be switched and executed using one antenna 11. As a result, the number of parts can be reduced, and the cost of the apparatus can be reduced. The specific configuration of the switch element 13 is not limited, and for example, any element that can be connected by switching circuits may be used.

In the DSRC method, radio waves having different frequencies are used for downlink communication and uplink communication. The radio wave used for downlink communication is a radio wave having a lower frequency than the radio wave used for uplink communication. In the DSRC method, a frequency difference of 40 MHz is defined for each radio wave used in downlink communication and uplink communication.

Therefore, the first and second frequencies corresponding to the DSRC method are different from each other. The first high frequency signal 51 is a signal having a frequency lower than that of the second high frequency signal 52, and the frequency difference between the first high frequency signal 51 and the second high frequency signal 52 is 40 MHz. In the present embodiment, the first high-frequency signal 51 corresponds to a reception signal generated in response to reception of a radio wave for narrow area communication, and the second high-frequency signal 52 is used for transmission of a radio wave for narrow area communication. It corresponds to the transmission signal used.

The receiving unit 20 includes a receiving amplifier 21, a quadrature mixer 22, and a band pass filter (BPF) 23.

The receiving amplifier 21 amplifies the first high-frequency signal 51 output via the switch element 13. In general, an electric signal converted from communication radio waves by the antenna 11 has a small intensity and is weak. The receiving amplifier 21 functions as a low noise amplifier (LNA: Low 増幅 Noise こうした Amplifier) that amplifies such a weak electric signal to an intensity used for signal processing or the like. The amplified electrical signal (first high frequency signal 51) is output to the orthogonal mixer 22.

As the receiving amplifier 21, an amplifier using, for example, a CMOS (Complementary Metal Oxide Semiconductor) circuit or the like is used. In addition, a low noise amplifier using, for example, gallium arsenide (GaAs) or silicon germanium (SiGe) may be used. Further, the gain, noise figure, etc. of the receiving amplifier 21 may be appropriately set according to the receiving sensitivity of the antenna 11 and the like.

The orthogonal mixer 22 converts the first high-frequency signal 51 amplified by the receiving amplifier 21 into an intermediate frequency. For the conversion to the intermediate frequency, a first reference signal 41 oscillated by a local oscillator 40 described later is used. The orthogonal mixer 22 converts the first high-frequency signal 51 into an intermediate frequency by mixing the first reference signal 41 and the first high-frequency signal 51.

Generally, when two signals having frequencies f1 and f2 are mixed, a signal obtained by integrating the signals is output. This integrated signal includes a frequency component having a frequency similar to the difference between the frequencies of the two signals (f1-f2). The integrated signal includes a frequency component having a frequency similar to the sum of the frequencies of the two signals (f1 + f2).

In the quadrature mixer 22, the first reference signal 41 and the first high-frequency signal 51 are mixed, so that the frequency component corresponding to the frequency difference and sum between the first reference signal 41 and the first high-frequency signal 51 is obtained. Is generated. In the present embodiment, the frequency difference between the first reference signal 41 and the first high-frequency signal 51 is an intermediate frequency. Therefore, for example, the intermediate frequency can be controlled to an arbitrary value by appropriately setting the frequency of the first reference signal 41.

As shown in FIG. 1, the quadrature mixer 22 outputs an I signal 53 and a Q signal 54 as intermediate frequency signals. The I signal 53 and the Q signal 54 are signals including data modulated by a quadrature phase shift keying (QPSK) method.

For example, the quadrature mixer 22 generates a reference I signal having the same phase (Inter-Phase) as the first reference signal 41 and a quadrature-phase reference Q signal having a phase shifted by 90 ° from the reference I signal. Generate. The reference I signal is generated by using the first reference signal output from the local oscillator 40 as it is. Further, the reference Q signal is generated by shifting the phase of the first reference signal 41 using a π / 2 phase shifter or the like that shifts the phase by 90 °.

The first high frequency signal 51 and the reference I signal are mixed to generate an I signal 53. Further, the first high-frequency signal 51 and the reference Q signal are mixed to generate a Q signal 54. For mixing each signal, a mixer or the like that integrates and outputs two signals is used. As a result, the first high-frequency signal 51 is converted into an I signal 53 and a Q signal 54 including a frequency component of an intermediate frequency. The I signal 53 and the Q signal 54 are output to the band pass filter 23.

The quadrature mixer 22 is configured by a circuit including two mixers that respectively output an I signal 53 and a Q signal 54, for example. The specific configuration of the orthogonal mixer 22 is not limited, and for example, a circuit that can output the I signal 53 and the Q signal 54 may be used as appropriate. Hereinafter, the I signal 53 and the Q signal 54 may be referred to as a first I / Q signal 55.

The band pass filter 23 passes the frequency component of the first band including the intermediate frequency and regulates the frequency component not included in the first band. That is, the band pass filter 23 extracts the frequency component of the intermediate frequency included in the first I / Q signal 55 output from the quadrature mixer 22. In the present embodiment, the bandpass filter 23 corresponds to a first internal filter.

The first band is set based on, for example, the occupied bandwidth (4.4 MHz) of each channel used in the DSRC method. For example, a band with a bandwidth of 4.4 MHz centered on the intermediate frequency is set as the first band. Thereby, for example, the frequency component corresponding to the sum of the frequencies of the first reference signal 41 and the first high frequency signal 51, other noise components, and the like can be sufficiently reduced. However, the present invention is not limited to this. For example, an arbitrary band in which the frequency component of the intermediate frequency can be extracted may be set as the first band.

The band pass filter 23 is an internal filter configured in an integrated circuit, and is configured by, for example, a resistor, a capacitor, a transistor, or the like on a chip. In addition, the specific configuration of the bandpass filter 23 is not limited. For example, a filter that can extract a frequency component of an intermediate frequency may be used as appropriate.

The first I / Q signal 55 filtered by the band-pass filter 23 is output to a subsequent circuit and demodulated by the QPSK method. In the DSRC method, an amplitude shift keying (ASK) method is used in addition to the QPSK method. For example, by detecting the signal strength of the I signal 53 and the Q signal 54 (first I / Q signal 55), it is possible to perform demodulation using the ASK method.

In the present embodiment, the reception unit 20 corresponds to a conversion unit that converts a reception signal generated in response to reception of radio waves for narrow area communication to an intermediate frequency based on the first reference signal.

The transmission unit 30 includes a modulation unit 31 and a transmission amplifier 32.

The modulation unit 31 modulates the baseband signal generated by the controller based on the second reference signal 42 supplied from the local oscillator 40 to generate a second high-frequency signal. The second reference signal 42 is a signal having a frequency different from that of the first reference signal 41. In the present embodiment, the frequency of the second reference signal 42 is set to the second frequency used in uplink communication. The modulation unit 31 generates the second high-frequency signal 52 having the second frequency by mixing the second reference signal 42 with the baseband signal.

As shown in FIG. 1, a baseband signal corresponding to the QPSK system or the ASK system is input to the modulation unit 31. In FIG. 1, the baseband signals are illustrated as an I signal 56 and a Q signal 57 (second I / Q signal 58).

The modulation unit 31 generates a reference I signal having the same phase as the second reference signal 42 and a reference Q signal having a quadrature phase that is 90 ° out of phase with the reference I signal. The modulation unit 31 mixes the reference I signal and the I signal 56, and mixes the reference Q signal and the Q signal 57. The mixed I signal 56 and the mixed Q signal 57 are added using an adding circuit or the like and output. As a result, the second high frequency signal 52 having the second frequency including the information of the I signal 56 and the Q signal 57 is generated.

The transmission amplifier 32 amplifies the second high-frequency signal 52 generated by the modulation unit 31. In general, the intensity of a radio wave transmitted from the antenna 11 is a value corresponding to the intensity of an electric signal input to the antenna 11. The transmission amplifier 32 functions as a power amplifier (PA) that amplifies the second high-frequency signal so that the radio wave is transmitted from the antenna 11 with an appropriate intensity. The amplified second high frequency signal is output to the communication unit 10.

As the transmission amplifier 32, for example, an amplifier using a CMOS circuit or the like is used. Further, the gain, noise figure, and the like of the transmission amplifier 32 may be appropriately set according to the reception sensitivity of the antenna 11 and the like.

In the present embodiment, the transmission unit 30 corresponds to a generation unit that generates a transmission signal used for transmission of radio waves for narrow area communication based on a second reference signal having a frequency different from that of the first reference signal. .

The local oscillator 40 switches between the supply of the first reference signal 41 to the reception unit 20 and the supply of the second reference signal 42 to the transmission unit 30 according to transmission / reception of the DSRC radio wave. That is, when a radio wave having the first frequency is received, the first reference signal 41 is supplied to the receiving unit 20, and when a radio wave having the second frequency is transmitted, the second reference signal 42 is supplied. Is supplied to the transmitter. In the present embodiment, the local oscillator 40 corresponds to a supply unit.

For example, when the wireless communication apparatus 100 is in a state of performing reception / transmission, a control signal indicating the reception state / transmission state is output from the controller. Based on the communication state signal, the local oscillator 40 oscillates the first reference signal 41 in the reception state and oscillates the second reference signal 42 in the transmission state. Thereby, the supply of the first and second reference signals 41 and 42 can be switched. The method for switching the supply of the first and second reference signals 41 and 42 is not limited, and an arbitrary method may be used.

As the local oscillator 40, a phase lock (PLL: Phase lock loop) circuit capable of oscillating by switching the first and second reference signals 41 and 42 is used. As shown in FIG. 1, the LO reference clock signal 43 is input to the PLL circuit. The LO reference clock signal 43 is a clock signal with high frequency stability generated using a crystal resonator or the like.

In the PLL circuit, feedback control is executed, and a periodic signal based on the LO reference clock signal 43 is generated. It is possible to change the frequency of the generated signal by appropriately manipulating the signal used for this feedback control.

For example, by changing the signal used for feedback control according to the communication state of the wireless communication device 100, the first and second reference signals 41 and 42 having different frequencies can be switched and generated. . The specific configuration of the local oscillator 40 is not limited, and an arbitrary oscillation circuit or the like that can switch and supply the first and second reference signals 41 and 42 may be used.

The controller has hardware necessary for the configuration of the computer, such as a CPU, ROM, RAM, and HDD. The wireless communication method according to the present technology is executed when the CPU loads a program recorded in advance in the ROM or the like to the RAM and executes the program. The specific configuration of the controller is not limited, and a device such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) may be used.

The program is installed in the wireless communication apparatus 100 via various recording media, for example. Alternatively, program installation may be executed via the Internet or the like.

The controller controls the overall operation of the wireless communication device 100. For example, the controller generates a control signal indicating the reception state and the transmission state in accordance with the communication state. Based on the generated control signal, the operations of the switch element 13 and the local oscillator 40 are controlled.

Also, the controller processes communication data transmitted / received by the DSRC method. For example, data for transmission is generated based on the received data. The data for transmission is output to the transmission unit 30 as a baseband signal (second I / Q signal 58).

FIG. 2 is a diagram schematically showing the relationship of channels used for DSRC communication. In the DSRC method, a channel is set for each communication frequency, and downlink communication and uplink communication are executed using a channel pair having a frequency difference of 40 MHz. In addition, the occupied bandwidth of each frequency channel is defined to be 4.4 MHz.

In the DSRC system, seven channels every 5 MHz of 5775 MHz, 5780 MHz,..., 5805 MHz are defined for downlink communication. In addition, 5815 MHz, 5820 MHz,..., 5845 MHz every 5 MHz channels are defined for uplink communication. Among these channels, a downlink communication channel and an uplink communication channel having a frequency difference of 40 MHz are paired.

Therefore, as shown in FIG. 2, in the DSRC system, seven pairs A to G of channels for downlink communication and uplink communication are prepared. Communication between the base station or the like and the wireless communication apparatus 100 is performed using one of these pairs. For example, in the pair A, a 5775 MHz downlink communication channel and a 5815 MHz uplink communication channel are used. Note that the base station performs communication with a fixed channel, and the radio communication apparatus 100 performs communication according to the channel used by the base station.

For example, it is assumed that a vehicle equipped with the wireless communication device 100 passes through the vicinity of the roadside where the base station is installed. Initially, the channel (downlink communication channel) used by the base station is unknown, and the wireless communication device 100 searches for a channel. When a downlink communication channel is selected, radio communication apparatus 100 sets the selected channel as a reception channel, and sets a channel paired with the reception channel as a transmission channel.

Suppose that, for example, 5790 MHz and 5830 MHz (pair D) are set as reception and transmission channels. When the wireless communication device 100 is in a transmission state, the local oscillator 40 oscillates a signal having a frequency of 5830 MHz as the second reference signal and supplies the signal to the transmission unit 30. In the transmission unit 30, the modulation unit 31 mixes the 5830 MHz second reference signal and the baseband signal to generate a 5830 MHz second high-frequency signal 52. The generated second high frequency signal is output to the communication unit 10.

The communication unit 10 transmits a radio wave of 5830 MHz based on the second high-frequency signal 52. When the radio wave is transmitted, the wireless communication device 100 shifts to a reception state in which a response from the base station is received. For example, the switch element 13 switches the connection destination of the communication unit 10 from the transmission unit 30 to the reception unit 20. The local oscillator 40 switches the oscillation frequency from the second reference signal 42 to the first reference signal 41.

A 5790 MHz radio wave is transmitted from the base station as a response to the wireless communication apparatus 100. The communication unit 10 receives a 5775 MHz radio wave and generates a first high frequency signal 51 of 5790 MHz. The generated first high frequency signal 51 is input to the receiving unit 20.

In the receiving unit 20, the first reference signal 41 and the first high frequency signal 51 are mixed by the orthogonal mixer 22, and the first high frequency signal 51 is converted into a first I / Q signal 55 having an intermediate frequency. Is done. The first I / Q signal 55 is demodulated by a subsequent circuit, and the response content from the base station is output to the controller. As described above, in the wireless communication apparatus 100, communication with the base station is performed using a channel pair of downlink communication and uplink communication. In the above description, the channel of pair D is taken as an example, but other channel pairs may of course be used.

FIG. 3 is a schematic diagram showing channel frequency relationships. In FIG. 3, a reception channel 60 (downlink communication channel) used by the wireless communication apparatus 100 for reception and the next

adjacent channels

61 a and 61 b are schematically illustrated. Note that the horizontal axis in the figure is the frequency, and the scale is set so that the center frequency of the reception channel 60 is 0 Hz.

The next

adjacent channels

61a and 61b are the second closest channels on the low frequency side and the high frequency side of the reception channel 60. For example, when the reception channel 60 is the 5790 MHz channel of the pair D shown in FIG. 2, the next

adjacent channels

61 a and 61 b are 5780 MHz and 5800 MHz channels. That is, the next

adjacent channels

61a and 61b are channels separated from the reception channel 60 by 10 MHz on the low frequency side and the high frequency side.

In the DSRC method, in order to avoid or reduce communication errors due to interference between adjacent channels or leakage power, there are restrictions on the use of the two adjacent channels. For this reason, the two adjacent channels are rarely received at the same time. Therefore, for the reception channel 60, there is a high possibility that communication performed in the next closest

adjacent channels

61a and 61b becomes a main interference wave.

For example, in addition to the radio wave of the reception channel 60, it is conceivable that interference waves of the next

adjacent channels

61a and 61b are received. In this case, the communication unit 10 outputs a signal including the frequency component of the reception channel 60 and the frequency components of the next

adjacent channels

61a and 61b. Therefore, the communication unit 10 outputs a signal including the first high-frequency signal 51 (frequency component of the reception channel 60) and the interference signal 62 (frequency component of the next

adjacent channels

61a and 61b).

The first high frequency signal 51 is mixed with the first reference signal 41 by the orthogonal mixer 22, and the frequency components of the reception channel 60 and the next

adjacent channels

61a and 61b are frequency-converted, respectively. As a result, the center of the reception channel 60 is shifted to the intermediate frequency, and the centers of the next

adjacent channels

61a and 61b are shifted to a frequency 10 MHz away from the intermediate frequency on the low frequency side and the high frequency side, respectively. That is, the frequency component of each channel is uniformly shifted to the lower frequency side by the frequency of the first reference signal 41.

The frequency component of each channel shifted to the low frequency side is input to the band pass filter 23 of the receiving unit 20. The first band of the bandpass filter 23 is set so as to extract the frequency component of the reception channel 60 and regulate the frequency components of the next

adjacent channels

61a and 61b. That is, the band pass filter 23 is configured to remove the interference signal 62 (frequency components of the next

adjacent channels

61a and 61b) that is 10 MHz away from the intermediate frequency.

Generally, when the width of the pass band of the filter is constant, the filter can be easily configured as the frequency at which the pass band is set is lower. For example, when a 10 MHz pass band is extracted in a frequency range of several tens of MHz, it may be necessary to provide an external filter or the like having a steep band pass characteristic. On the other hand, when a 10 MHz pass band is extracted in a frequency region of several MHz, it is possible to remove an interference signal using an internal filter or the like configured in the integrated circuit.

As described above, in this embodiment, the intermediate frequency can be controlled. Accordingly, by setting the frequency of the intermediate frequency in the low frequency region, the pass band (first band) of the bandpass filter 23 can be set in the low frequency region. As a result, the configuration of the bandpass filter 23 can be simplified. As a result, for example, an external filter or the like becomes unnecessary, and the apparatus can be downsized.

In this embodiment, the frequency of the first reference signal is controlled by the local oscillator 40 so that the intermediate frequency is smaller than the frequency difference between the first high-frequency signal 51 and the second high-frequency signal. Specifically, the first reference signal 41 is set so that the intermediate frequency becomes a value smaller than 40 MHz.

Since the value of the intermediate frequency is set small, the first band which is the pass band of the band pass filter 23 is also set in the low frequency region. That is, the center frequency of the first band is set to a frequency smaller than 40 MHz. Thereby, for example, the band-pass filter 23 can be configured as an internal filter, and the apparatus can be sufficiently downsized.

The frequency difference between the frequency component of the reception channel 60 output from the orthogonal mixer 22 and each frequency component of the next

adjacent channels

61a and 61b remains at 10 MHz regardless of the value of the intermediate frequency. For this reason, even when the value of the intermediate frequency is reduced, the width of the pass band (first band) of the band pass filter 23 is hardly changed. Therefore, the smaller the value of the intermediate frequency, the lower the frequency at which the pass band is set, and the frequency component of the reception channel 60 can be easily extracted.

FIG. 4 is a schematic diagram showing an example of conversion to an intermediate frequency by the orthogonal mixer 22. 4A to 4C schematically show the reception channel 60 and the next

adjacent channels

61a and 61b whose frequencies are shifted by the orthogonal mixer 22. FIG.

周波数 When the value of the intermediate frequency is lowered, a frequency component with a negative frequency is generated. The negative frequency is, for example, a frequency generated by frequency subtraction in the mixer (orthogonal mixer 22). For example, when a signal having a frequency f1 and a signal having a frequency f2 higher than f1 are mixed, the frequency difference (f1-f2) between the two signals is apparently negative. In this case, the frequency component of the absolute value | f1-f2 | of the frequency difference between the two signals is output from the mixer. This frequency component can be regarded as a component folded with 0 Hz as a reference, which causes image interference and the like.

As shown in FIG. 4A, for example, when the intermediate frequency is set to 10 MHz, the center frequency of the next adjacent channel 61a on the low frequency side is 0 Hz. In this case, the negative frequency component of the next adjacent channel 61a is folded back on the basis of 0 Hz and detected as a positive frequency. Accordingly, the interference signal 62 corresponding to the next adjacent channel 61a is a signal having a frequency component from 0 Hz to 2.2 MHz.

As described above, when the value of the intermediate frequency is lowered, the interference signal 62 and the like of the next adjacent channel 61a are turned back at 0 Hz. Depending on the value of the intermediate frequency, the folded interference signal 62 may overlap the reception channel 60. In this case, it is difficult to remove the interference signal 62 by using the subsequent bandpass filter 23 and the like, and a communication error may occur.

In the present embodiment, the absolute value of the intermediate frequency is set to be approximately 2.2 MHz or more and 2.8 MHz or less. That is, if the intermediate frequency is Fi, the intermediate frequency Fi is set so that −2.8 MHz ≦ Fi ≦ −2.2 MHz or 2.2 MHz ≦ Fi ≦ 2.8 MHz.

For example, when the intermediate frequency is set to 2.2 MHz, the band of the reception channel 60 is 0 Hz to 4.4 MHz. Further, the next adjacent channel 61 a on the low frequency side is folded back at 0 Hz, and the band does not overlap with the reception channel 60. As a result, the intermediate frequency can be lowered to the minimum frequency at which no aliasing occurs in the reception channel 60.

For example, when the intermediate frequency is set to 2.8 MHz, the upper limit frequency of the band of the reception channel 60 is 5 MHz. Further, the next adjacent channel 61a on the low frequency side is folded at 0 Hz, and the lower limit frequency of the band is 5 MHz. Therefore, the reception channel 60 and the next adjacent channel 61a come into contact with each other at 5 MHz. Even in this case, the bandwidth of each channel does not overlap.

When the intermediate frequency is in the range of 2.2 MHz to 2.8 MHz, the next adjacent channel 61 a on the low frequency side does not overlap the reception channel 60. This makes it possible to sufficiently reduce the value of the intermediate frequency while avoiding the influence of image interference or the like. As a result, the configuration of the bandpass filter 23 can be greatly simplified, and the apparatus can be sufficiently downsized.

Note that when the intermediate frequency is negative, the reception channel 60 is folded back with respect to 0 Hz. In this case, by setting the intermediate frequency to be −2.8 MHz or more and −2.2 MHz or less, the reception channel 60 can be turned back so as not to overlap with the next adjacent channel 61b on the high frequency side. Thereby, the configuration of the bandpass filter 23 can be greatly simplified.

In this embodiment, the absolute value of the intermediate frequency is set to approximately 2.5 MHz. That is, the first reference signal is set in accordance with the frequency of the reception channel 60 so that the value of the intermediate frequency is +2.5 MHz or −2.5 MHz. 4B and 4C show the frequency relationship of each channel when the intermediate frequency is +2.5 MHz and −2.5 MHz.

For example, assume that the reception channel 60 is 5790 MHz. In this case, by setting the frequency of the first reference signal 41 to 5787.5 MHz, the intermediate frequency becomes 2.5 MHz. Further, by setting the frequency of the first reference signal 41 to 5792.5 MHz, the intermediate frequency becomes −2.5 MHz. When another reception channel 60 is selected, the first reference signal 41 is appropriately set according to the frequency of the selected reception channel 60 so that the absolute value of the intermediate frequency is approximately 2.5 MHz. .

As shown in FIG. 4B, when the reception channel 60 is converted to +2.5 MHz, the next adjacent channel 61a on the low frequency side is converted to -7.5 MHz. Therefore, the next adjacent channel 61a on the low frequency side is folded back into a channel having a center frequency of +7.5 MHz. Therefore, the orthogonal mixer 22 outputs a signal in which the frequency components of the reception channel 60, the low frequency side next adjacent channel 61a, and the high frequency side next adjacent channel 61b are arranged in this order at intervals of 5 MHz.

As shown in FIG. 4C, when the reception channel 60 is converted to −2.5 MHz, the reception channel 60 is folded back into a channel having a center frequency of 2.5 MHz. Further, the next adjacent channel 61a on the low frequency side is folded from -12.5 MHz to +12.5 MHz. Therefore, the orthogonal mixer 22 outputs a signal in which the frequency components of the reception channel 60, the high frequency side next adjacent channel 61b, and the low frequency side next adjacent channel 61a are arranged in this order at intervals of 5 MHz.

The first reference signal 41 for setting the absolute value of the intermediate frequency to approximately 2.5 MHz can be easily generated using, for example, a circuit for searching for a reception channel. As described above, the downlink communication channel interval is 5 MHz, and the circuit for searching for the reception channel changes the frequency in 5 MHz steps. For example, the frequency step can be easily changed to 2.5 MHz by using a division period that divides the frequency by 1/2, and the first reference signal 41 can be easily generated. It is.

Thus, when the absolute value of the intermediate frequency is set to approximately 2.5 MHz, the first reference signal can be easily supplied. Thereby, it is possible to easily realize a sufficiently small intermediate frequency while avoiding the influence of image interference or the like. As a result, it is possible to provide a small apparatus with a small number of parts.

In the above, the intermediate frequency (IF: Intermediate Frequency) is set to a value smaller than the frequency difference between the first high-frequency signal 51 and the second high-frequency signal (frequency difference between the reception channel and the transmission channel). In such a Low-IF method in which the intermediate frequency is set to a low value, for example, the number of frequency conversions until demodulation can be reduced, and the number of parts can be reduced.

This technology can be applied not only to the Low-IF method but also to the Zero-IF method. In the zero-IF scheme, the intermediate frequency is set to be substantially zero, and direct conversion for directly demodulating the baseband signal from the first high-frequency signal 51 is executed. As shown in FIG. 5, by providing a low-pass filter (LPF: Low Pass Filter) 24 at the subsequent stage of the orthogonal mixer 22, it is possible to execute communication in the zero-IF system.

In the zero-IF method, the local oscillator 40 controls the frequency of the first reference signal 41 so that the intermediate frequency becomes substantially zero. For example, by setting the first reference signal 41 to a frequency substantially the same as that of the reception channel 60, the intermediate frequency can be made substantially zero. When the wireless communication device 200 is in a reception state, the first reference signal 41 having the same frequency as that of the reception channel 60 is oscillated by the local oscillator 40. The oscillated first reference signal 41 is supplied to the quadrature mixer 22.

The orthogonal mixer 22 mixes the first high-frequency signal 51 and the first reference signal 41 having the same frequency as the reception channel 60. As a result, the orthogonal mixer 22 generates a signal including frequency components corresponding to the difference and sum of the same frequencies (frequency of the reception channel 60).

The frequency difference between the first high-frequency signal 51 and the first reference signal 41 is approximately 0 Hz, and the frequency component corresponds to the component of the baseband signal. The sum of the frequencies is approximately twice the frequency of the reception channel 60, and the frequency component becomes a high frequency noise component. From the orthogonal mixer 22, a signal including a baseband signal component and a high-frequency noise component is output to the low-pass filter 24.

In the quadrature mixer 22, the baseband signal is demodulated by dividing it into an I signal 53 and a Q signal 54. As described above, the I signal 53 and the Q signal 54 are demodulated based on the reference I signal and the reference Q signal whose phases are orthogonal to each other. For this reason, it is possible to realize the demodulation of the baseband signal while avoiding the influence of the image interference or the like accompanying the frequency folding. Thus, it can be said that the orthogonal mixer 22 functions as an I / Q demodulator that demodulates the I / Q signal.

The low-pass filter 24 is configured in the integrated circuit as an internal filter. The low-pass filter 24 passes the frequency component of the second band including the intermediate frequency, and regulates a frequency component higher than the upper limit frequency of the second band. The second band is, for example, a band from 0 Hz to the upper limit frequency. In the present embodiment, the low-pass filter 24 corresponds to a second internal filter.

The upper limit frequency of the second band is set based on the frequency of the channel used in the DSRC method, for example. For example, as described with reference to FIG. 2, in the DSRC system, the pair A downlink communication channel (5775 MHz) is the lowest frequency channel. As the upper limit frequency, for example, a frequency lower than the frequency of the downlink communication channel of pair A is set.

By setting the upper limit frequency lower than the lowest frequency channel of the DSRC system, it becomes possible to sufficiently attenuate the frequency components of each channel, noise signals having twice the frequency of each channel, and the like. As a result, the baseband signal output from the orthogonal mixer 22 can be extracted with high accuracy. The method for setting the upper limit frequency is not limited. For example, the upper limit frequency may be appropriately set according to the circuit configuration at the subsequent stage.

The extracted baseband signal is directly converted into a digital signal, for example, and output to the controller. As described above, in the zero-IF method, the baseband signal is directly demodulated, so that the number of components used for frequency conversion and the like can be greatly reduced. As a result, the apparatus can be sufficiently downsized.

As described above, in the wireless communication apparatus 100 according to the present embodiment, the first and second reference signals 41 and 42 having different frequencies are appropriately switched and supplied to the reception unit 20 and the transmission unit 30. As a result, for example, the intermediate frequency can be controlled, and data can be received without using an external filter or the like. As a result, the wireless communication device 100 can be reduced in size.

FIG. 6 is a schematic diagram showing a configuration example of a wireless communication apparatus 300 given as a comparative example. As a communication method in the DSRC system, a method of operating each circuit on the transmission side and the reception side based on an LO oscillation signal having the same frequency is conceivable. In this method, the reception channel signal is converted to an intermediate frequency using the frequency used to generate the transmission channel signal. In the DSRC system, the frequency difference between the transmission channel and the reception channel is defined as 40 MHz, and the intermediate frequency is 40 MHz.

In the wireless communication apparatus 300, the local oscillator 340 outputs the LO oscillation signal 341 having the same frequency to the reception-side circuit (reception unit 320) and the transmission-side circuit (transmission unit 330). As shown in FIG. 6, in the receiving unit 320, the mixer 322 mixes the reception channel signal output from the reception amplifier 321 and the LO oscillation signal 341, and generates an IF signal 355 having an intermediate frequency of 40 MHz. Is output.

When the intermediate frequency is 40 MHz, a filter having a steep bandpass characteristic is required to ensure sufficient selectivity for the next adjacent channel separated by 10 MHz. For this reason, an external SAW (Surface Acoustic Wave) filter 323 as shown in FIG. 6 is indispensable. Since the SAW filter 323 is provided outside, for example, it is difficult to fit the receiving side circuit on the chip. In addition, there is a problem that the entire circuit becomes large due to the external wiring and securing the installation position.

In the wireless communication apparatus 100 according to the present embodiment, the local oscillator 40 oscillates the first and second reference signals 41 and 42 having different frequencies from each other in accordance with the communication state of the wireless communication apparatus 100. In the reception state, the first reference signal 41 is supplied to the reception unit 20, and in the transmission state, the second reference signal 42 is supplied to the transmission unit 30. Thus, since the first and second reference signals 41 and 42 can be switched according to the communication state, the intermediate frequency can be set to a desired value.

The frequency of the first reference signal 41 is controlled so that the intermediate frequency is smaller than 40 MHz which is the frequency difference between the first and second high-

frequency signals

51 and 52. By setting the intermediate frequency low, an external filter such as a SAW filter becomes unnecessary. For this reason, wiring and installation surfaces for providing a SAW filter or the like are not necessary, and the size of the apparatus can be reduced while suppressing costs.

Further, it becomes possible to configure the band pass filter 23 for filtering the intermediate frequency signal as an internal filter in the integrated circuit. As a result, the receiving unit 20 can be accommodated in the chip, and the apparatus can be sufficiently downsized.

In this embodiment, the intermediate frequency is set to approximately 2.5 MHz. As a result, it is possible to sufficiently avoid image interference caused by frequency components such as the next adjacent channel in the DSRC system. As a result, for example, even when the image rejection ratio of the wireless communication apparatus 100 is small, communication can be performed with high accuracy.

<Second Embodiment>
A wireless communication device according to a second embodiment of the present technology will be described. In the following description, the description of the same part as the configuration and operation of the wireless communication apparatus 400 described in the above embodiment will be omitted or simplified.

FIG. 7 is a schematic diagram illustrating a configuration example of the wireless communication apparatus 400 according to the second embodiment. The wireless communication device 400 includes a communication unit 410, a reception unit 420, a transmission unit 430, a local oscillator 440, and a frequency divider 460. The communication unit 410 has the same configuration as the communication unit 410 shown in FIG.

The receiving unit 420 includes a receiving amplifier 421, a first mixer 422, an orthogonal mixer 423, and a filter unit 424. The receiving amplifier 421 has the same configuration as the receiving amplifier 21 of the receiving unit 20 shown in FIG. The reception amplifier 421 functions as an LNA that amplifies the first high-frequency signal 451 including the frequency component of the reception channel.

The first mixer 422 mixes the first high-frequency signal 451 amplified by the receiving amplifier 421 and the first reference signal 441 supplied from the local oscillator 440. The quadrature mixer 423 mixes the signal output from the first mixer 422 and the first divided signal 461 supplied from the divider 460. Thus, the first high-frequency signal 451 is frequency-converted in two stages by the first mixer 422 and the orthogonal mixer 423.

The frequency of the first high-frequency signal 451 is converted into four different frequencies by the frequency conversion twice. For example, assuming that the frequencies of the first high-frequency signal 451 (reception channel), the first reference signal, and the first frequency-divided signal are fr, fs1, and fd1, respectively, the orthogonal mixer 423 sends fr + fs1 + fd1, fr + fs1- Frequency components corresponding to the four frequencies fd1, fr-fs1 + fd1, and fr-fs1-fd1 are output.

Of these four frequencies, the lowest frequency (fr-fs1-fd1) is the intermediate frequency. As described above, in the present embodiment, the first high-frequency signal 451 is converted into an intermediate frequency by the first mixer 422 and the orthogonal mixer 423.

The filter unit 424 extracts the frequency component of the intermediate frequency from the signal output from the orthogonal mixer 423. For example, the filter unit 424 is configured as a band-pass filter (BPF) in the Low-IF scheme, and is configured as a low-pass filter (LPF) in the Zero-IF scheme. The configuration or the like of the filter unit 424 is not limited, and may be appropriately configured using, for example, the bandpass filter 23 illustrated in FIG. 1 or the lowpass filter 24 illustrated in FIG.

The transmission unit 430 includes a modulation unit 431, a second mixer 432, a band stop filter 433, and a transmission amplifier 434.

The modulation unit 431 mixes the baseband signal 458 and the second divided signal 462 supplied from the frequency divider 460. As a result, the baseband signal 458 is modulated into a signal having the same frequency as that of the second divided signal 462. The second mixer 432 mixes the signal output from the modulation unit 431 and the second reference signal 442 supplied from the local oscillator 440. Thus, the baseband signal 458 is frequency-converted in two stages by the modulation unit 431 and the second mixer 432.

The second mixer 432 outputs a signal including a frequency component corresponding to the difference and sum of the frequency fd2 of the second divided signal 462 and the frequency fs2 of the second reference signal 442. In the present embodiment, the sum (fd2 + fs2) of the frequencies of the second frequency-divided signal 462 and the second reference signal 442 becomes the frequency ft of the second high-frequency signal 452 (transmission channel). As described above, in the present embodiment, the modulation unit 431 and the second mixer 432 perform the mixing of the second divided signal 462 and the second reference signal 442 with respect to the baseband signal, and the second reference signal 442 is mixed. A high frequency signal 452 is generated.

The band stop filter 433 regulates the frequency component of the third band and passes the frequency component not included in the third band. The third band regulates the frequency component corresponding to the frequency difference between the second divided signal 462 and the second reference signal 442 among the signals output from the second mixer 432, for example, The frequency component corresponding to the sum is set to pass. Therefore, the frequency component of the second high frequency signal 452 (transmission channel) passes through the band stop filter 433.

The transmission amplifier 434 amplifies the second high frequency signal 452 that has passed through the band stop filter 433. The transmission amplifier 434 has the same configuration as the transmission amplifier 32 of the transmission unit 30 shown in FIG. The transmission amplifier 434 functions as a PA that amplifies the second high-frequency signal 452 including the frequency component of the transmission channel.

The local oscillator 440 oscillates by switching between the first reference signal 441 and the second reference signal 442 having a frequency different from that of the first reference signal 441 in accordance with transmission / reception of a DSRC radio wave. First and second reference signals 441 and 442 are supplied to first and

second mixers

422 and 432, respectively. The first and second reference signals 441 and 442 are branched at a branch point 445 and input to the frequency divider 460. As the local oscillator 440, a PLL circuit or the like that can oscillate by switching the first and second reference signals 441 and 442 is appropriately used.

The frequency divider 460 divides the frequency of the signals (first and second reference signals 441 and 442) oscillated by the local oscillator 440 at a predetermined ratio. For example, the frequency divider 460 divides the frequency of the first reference signal 441 by a predetermined ratio to generate the first frequency divided signal 461. The frequency divider 460 divides the frequency of the second reference signal 442 by a predetermined ratio to generate a second frequency divided signal 462. In the present embodiment, the frequency divider 460 corresponds to a frequency division unit, and the second frequency division signal 462 corresponds to a frequency division signal. In the present embodiment, the local oscillator 440 and the frequency divider 460 constitute a supply unit.

The predetermined ratio (frequency division ratio) for dividing the frequency is set to be 1/2, 1/4, or 1/6. As described above, the frequency divider 460 can be easily configured by using a simple frequency division ratio. In the example shown in FIG. 7, a frequency divider 460 having a frequency division ratio of 1/4 is used. For example, when a 5800 MHz signal is input to the frequency divider 460, a signal having a frequency of 5800/4 = 1450 MHz is output from the frequency divider 460.

Suppose that a reception channel and a transmission channel are set, and communication between the wireless communication apparatus 400 and the base station is performed. Hereinafter, the operation of radio communication apparatus 400 in uplink communication (transmission state) and downlink communication (reception state) will be described.

In the transmission state, the second reference signal 442 is oscillated by the local oscillator 440. In FIG. 7, the frequency fs2 of the second reference signal 442 is set to be 4/5 of the frequency ft of the transmission channel. The frequency divider 460 divides the frequency fs2 of the second reference signal 442 input via the branch point 445 by ¼ to generate a second divided signal 462. The frequency fd2 of the second divided signal 462 is fd2 = (fs2) / 4 = (ft × 4/5) / 4 = ft / 5.

The baseband signal and the second divided signal 462 are mixed by the modulation unit 431. A baseband signal modulated to a frequency of ft / 5 is output from the modulation unit 431 and input to the second mixer 432. The second mixer 432 mixes the signal output from the modulation unit 431 and the second reference signal 442 input via the branch point 445. In the second mixer 432, the frequency of each signal is added (ft / 5 + ft × 4/5 = ft) and subtracted (| ft / 5−ft × 4/5 | = ft × 3/5).

Therefore, the second mixer 432 outputs a second high-frequency signal 452 having the same frequency ft as that of the transmission channel and a signal having a frequency of ft × 3/5. The band stop filter 433 extracts the second high-frequency signal 452 from the output of the second mixer 432. Then, the second high-frequency signal 452 is amplified by the transmission amplifier 434 and transmitted to the communication unit 410.

As described above, the wireless communication apparatus 400 illustrated in FIG. 7 sets the frequency of the second reference signal 442 to 4/5 of the frequency of the transmission channel, so that the baseband signal is modulated to the frequency of the transmission channel. It is configured. That is, in the wireless communication device 400, the ratio between the oscillation frequency (LO frequency) of the local oscillator 440 and the frequency of the transmission channel (transmission frequency) is 4: 5.

Since the transmission frequency and the LO oscillation frequency are deviated, for example, it is possible to sufficiently reduce the influence of local pulling or the like on the local oscillator 440 from the transmission amplifier 434 that is a power amplifier. As a result, the local oscillator 440 can be stably operated, and communication errors, device malfunctions, and the like can be sufficiently suppressed.

In addition, since the transmission channel is 5 MHz intervals, when changing the channel, the frequency of the second reference signal 442 may be changed in steps of 5 MHz × 4/5 = 4 MHz. As a result, the circuit configuration for generating the second reference signal 442 can be simplified. As a result, the number of parts can be reduced, and the cost of parts can be reduced, and a highly reliable small device can be realized.

In the reception state, the first reference signal 441 is oscillated by the local oscillator 440. The frequency fs1 of the first reference signal 441 is set according to the frequency fr of the reception channel (first high frequency signal 451) so that the intermediate frequency fi becomes a predetermined value. The first divided signal 461 generated by dividing the first reference signal 441 and the first reference signal 441 is supplied to the receiving unit 420, and the first high-frequency signal 451 is converted into the intermediate frequency fi. .

In FIG. 7, the frequency fd1 of the first frequency-divided signal 461 is ¼ of the frequency fs1 of the first reference signal 441. As described above, the intermediate frequency fi is expressed as fr-fs1-fd1. Therefore, the intermediate frequency fi is fi = fr−fs1−fs1 / 4 = fr−fs1 × 5/4.

For example, in the zero-IF method, the frequency fs1 of the first reference signal 441 is set so that the intermediate frequency fi≈0 Hz. In this case, the intermediate frequency fi can be made substantially zero by setting the frequency fs1 of the first reference signal 441 to 4/5 of the frequency fr of the reception channel. In order to change the channel, the first reference signal may be changed in steps of 4 MHz.

Also, for example, in the Low-IF method, the first reference signal 441 can be set so that the intermediate frequency is fi≈2.5 MHz. In this case, by setting fs1 = fr × 4 / 5-2 MHz, the intermediate frequency fi can be set to approximately 2.5 MHz. That is, by creating a frequency shifted by 2 MHz from the frequency of the zero-IF method, it is possible to easily realize the Low-IF method with an intermediate frequency of 2.5 MHz.

As described above, the signals oscillated by the local oscillator 440 (first and second reference signals 441 and 442) and the signals obtained by dividing the signals (first and second divided signals 461 and 462) are used. Thus, the frequency conversion can be performed in two stages. By using such a sliding IF method for performing a plurality of frequency conversions, it is possible to easily realize a circuit configuration in which the influence of, for example, local pulling is sufficiently reduced.

Even when the frequency division ratio set in the frequency divider 460 is set to 1/2 or 1/6, the respective frequencies of the first and second reference signals 441 and 442 are appropriately set. The wireless communication device 400 can be configured. Of course, the frequency division ratio set in the frequency divider 460 is not present, and any frequency division ratio other than 1/2, 1/4, and 1/6 may be used. Further, the present technology is not limited to the case of performing two-stage frequency conversion, and the present technology can also be applied to the case of performing three-stage or four-stage frequency conversion. In this case, by performing frequency conversion a plurality of times, it is possible to sufficiently suppress the influence of frequency coupling (local pulling) or the like on the local oscillator 440.

<Third Embodiment>
FIG. 8 is a schematic diagram illustrating a configuration example of a wireless communication apparatus 500 according to the third embodiment. The wireless communication apparatus 500 includes a communication unit 510, a signal generation unit 570, and a system clock generation unit 580. The communication unit 510 has substantially the same configuration as each wireless communication device described in the above embodiment. 8 shows the configuration shown in FIG. 1, the configuration shown in FIGS. 5 and 7 may be used.

The signal generation unit 570 is a circuit provided in the subsequent stage of the reception unit 520 of the communication unit 510, and generates the data signal 550 based on the intermediate frequency signal. As illustrated in FIG. 8, the signal generation unit 570 includes a digital conversion unit 571, a digital signal processing unit 572, an analog conversion unit 573, and an orthogonal mixer 574.

The digital conversion unit 571 converts the I / Q signal 555 that is an intermediate frequency signal output from the reception unit 520 into a digital signal. As shown in FIG. 8, the I / Q signal 555 is a signal including an I signal 553 and a Q signal 554. The digital conversion unit 571 converts the I signal 553 and the Q signal 554 into digital signals, respectively. Hereinafter, the processing performed for each of the I signal 553 and the Q signal 554 may be described as processing for the I / Q signal 555.

As the digital conversion unit 571, for example, an ADC (Analog-to-Digital Converter) or the like is used. The specific configuration of the digital conversion unit 571 is not limited. For example, an arbitrary digital conversion circuit capable of digitally sampling a baseband signal may be used as appropriate.

The digital signal processing unit 572 processes the I / Q signal 555 in the digital domain. As illustrated in FIG. 8, the digital signal processing unit 572 includes a channel selection filter 575, a level detection unit 576, and a frequency conversion unit 577.

The channel selection filter 575 filters the I / Q signal 555 converted into a digital signal. The channel selection filter 575 removes, for example, noise components that could not be removed by the analog filter (BPF or LPF) of the receiving unit 520. As a result, it is possible to extract the frequency component included in the reception channel converted to the intermediate frequency with high accuracy, and it is possible to remove the components of other channels with high accuracy.

The level detection unit 576 detects the amplitude intensity of the I / Q signal 555 output from the channel selection filter 575. For example, it is possible to detect a signal modulated by the ASK method by detecting a temporal change in the amplitude of the I / Q signal 555. For example, the level detection unit 576 converts the amplitude intensity of the I / Q signal 555 into bits and outputs it as an ASK detection output 556. In the present embodiment, the ASK detection output 556 corresponds to an ASK signal.

Also, for example, based on the amplitude intensity of the I / Q signal 555, it is possible to determine whether or not a carrier wave (carrier) exists in the target frequency (channel). For example, when the amplitude intensity is smaller than a predetermined threshold, it is determined that there is no carrier, and when larger than the predetermined threshold, it is determined that a carrier exists. The determination result is output as a carrier detection output 557 and used for selection of a reception channel. In the present embodiment, the carrier detection output 557 corresponds to a carrier strength signal.

The frequency converter 577 converts the frequency of the I / Q signal 555 output from the channel selection filter 575 to approximately 0 Hz by frequency conversion in the digital domain. This can also be said to be converting an I / Q signal into a baseband signal in the digital domain. As a result, for example, it is possible to correct a shift in the LO reference clock signal between the base station and the wireless communication apparatus 500. The I / Q signal 555 frequency-converted to approximately 0 Hz is output to the analog conversion unit 573.

Thus, the digital signal processing unit 572 performs various digital processes on the I / Q signal 555. As the digital signal processing unit, for example, a DSP (Digital Signal Processor) programmed with digital signal filtering processing or the like is used. In addition, the specific configuration of the digital signal processing unit 572 is not limited. In addition, the channel selection filter 575, the level detection unit 576, and the frequency conversion unit 577 may be configured by individual elements.

Analog conversion unit 573 converts I / Q signal 555 output from frequency conversion unit 577 into an analog signal. As the analog conversion unit 573, for example, a DAC (Digital-to-Analog Converter) or the like is used. The specific configuration of the analog conversion unit 573 is not limited.

In this embodiment, the digital conversion unit 571, the digital signal processing unit 572, and the analog conversion unit 573 constitute a digital filter unit that digitizes and filters an intermediate frequency signal.

The orthogonal mixer 574 mixes the I / Q signal 555 converted into the analog signal and the reference signal 581 having the demodulation frequency output from the system clock generation unit 580. As the demodulation frequency, a frequency (8.192 MHz) based on the system reference clock signal 582 used in a subsequent signal processing circuit (controller or the like) is set.

The quadrature mixer 574 converts the I signal 553 and the Q signal 554 (I / Q signal 555) into demodulation frequencies. The converted I signal 553 and Q signal 554 are added using an adder circuit or the like and output as a QPSK output 558. In the present embodiment, the orthogonal mixer 574 corresponds to a mixer unit that converts the output of the digital filter unit into a frequency for demodulation. In the present embodiment, the QPSK output 558 corresponds to a QPSK signal.

Based on the system clock generation unit 580 and the system reference clock signal 582, a system clock signal 583 and a reference signal 581 for demodulation input to a signal processing circuit or the like are generated. The frequencies of the system clock signal 583 and the reference signal 581 may be the same as each other or different from each other. As the system clock generator 580, for example, a PLL circuit prepared for signal processing is used.

As shown in FIG. 8, the system clock signal 583 is output to a signal processing circuit such as a digital conversion unit 571, a digital signal processing unit 572, an analog conversion unit 573, and a subsequent controller. The demodulation reference signal 581 is output to the orthogonal mixer 574. As described above, each unit included in the signal generation unit 570 operates based on the system reference clock signal 582. In the present embodiment, the system reference clock signal 582 corresponds to a reference clock signal.

For example, assume that the wireless communication device 500 is searching for a reception channel. In this case, the receiving unit 520 sequentially outputs, for example, I / Q signals 555 corresponding to seven downlink communication channels (see FIG. 2). The signal generation unit 570 performs digital domain filtering on each I / Q signal 555 and outputs a carrier detection output 557 based on the amplitude intensity of the I / Q signal 555. Thereby, it is possible to select a channel (reception channel) that the base station uses for transmission from the seven channels.

For example, when the wireless communication device 500 is in a reception state, the reception unit 520 outputs an I / Q signal 555 corresponding to the reception channel. The signal generation unit 570 performs digital domain filtering on the I / Q signal 555 of the reception channel, and outputs an ASK detection output 556 based on the amplitude intensity of the I / Q signal 555. In addition, the signal generation unit 570 performs frequency conversion in the digital domain and the analog domain on the filtered I / Q signal 555 and outputs the result as a QPSK output 558.

Thus, the signal generation unit 570 generates the data signal 550 including the QPSK output 558, the ASK detection output 556, and the carrier detection output 557 based on the intermediate frequency signal. As a result, for example, a data signal can be generated in accordance with a subsequent circuit (controller) that performs data processing or the like, and high versatility is exhibited.

For example, in the wireless communication apparatus 300 shown as a comparative example in FIG. 6, a QPSK output 358, an ASK detection output 356, and a carrier detection output 357 are generated based on a signal converted to an intermediate frequency of 40 MHz. In the wireless communication apparatus 300 shown in FIG. 6, a dedicated reference signal 381 for performing frequency conversion from 40 MHz to 8.192 MHz is necessary to generate the QPSK output 358. Therefore, in FIG. 6, a dedicated oscillation circuit 384 including a crystal resonator 382 and a PLL circuit 383 is required.

In the wireless communication apparatus 500 according to the present embodiment, the reference signal 581 for conversion to a demodulation frequency (8.192 MHz) is generated by a system clock generation unit 580 that oscillates a system clock used in a controller or the like. . Therefore, a dedicated oscillation circuit or the like for converting the I / Q signal 555 into a demodulation frequency is unnecessary, and the number of parts can be suppressed. As a result, the apparatus can be sufficiently downsized.

Further, the wireless communication device 500 can output the same data signal 550 as the wireless communication device 300 shown in FIG. From another point of view, a signal processing circuit (controller or the like) used in the subsequent stage of the wireless communication apparatus 300 shown in FIG. 6 can be used as the subsequent stage of the wireless communication apparatus 500 according to the present embodiment. It can also be said. As described above, by applying the present technology, it is possible to provide the wireless communication device 500 having a small device size and high versatility.

In this embodiment, the signal generation unit 570 filters the I / Q signal 555 in the digital domain. Therefore, in the wireless communication apparatus 500, the I / Q signal 555 is filtered in two stages by the analog filter (LPF or BPF) of the reception unit 20 and the digital filter of the signal generation unit. As a result, the data signal 550 such as the QPSK output 558 and the ASK detection output 556 can be generated with high accuracy, and the communication accuracy can be greatly improved.

<Other embodiments>
The present technology is not limited to the embodiments described above, and other various embodiments can be realized.

In the wireless communication apparatus 500 shown in FIG. 8, an I / Q signal having an intermediate frequency is converted into a demodulation frequency in order to execute demodulation of the QPSK method. For example, an I / Q signal having a demodulation frequency may be directly generated by an orthogonal mixer of the receiving unit. That is, the intermediate frequency may be set to 8.192 MHz. In this case, the frequency conversion necessary until the demodulation process is performed once, and the number of parts can be reduced. However, the present invention is not limited to this, and the value of the intermediate frequency may be set as appropriate according to the processing in the subsequent stage.

In the above embodiment, the

wireless communication devices

100, 200, 400, and 500 are configured as on-vehicle devices that are mobile stations. The present technology is not limited to this, and the present technology can be applied even when the wireless communication device is configured as a base station.

For example, the value of the intermediate frequency can be controlled by appropriately switching the oscillation frequency of the local oscillator according to the transmission state and reception state of the base station. As a result, the apparatus can be configured without using an external filter or the like, and the apparatus can be downsized. In addition, the wireless communication device according to the present technology can be configured as a device such as a mobile device or a wearable device without being limited to the vehicle-mounted device mounted on the vehicle or the like.

Of the characteristic parts according to the present technology described above, it is possible to combine at least two characteristic parts. That is, the various characteristic parts described in each embodiment may be arbitrarily combined without distinction between the embodiments. The various effects described above are merely examples and are not limited, and other effects may be exhibited.

In addition, this technique can also take the following structures.
(1) a communication unit capable of transmitting and receiving radio waves for narrow area communication;
A conversion unit that converts a reception signal generated in response to reception of the radio wave for narrow area communication into an intermediate frequency based on a first reference signal;
Based on a second reference signal having a frequency different from that of the first reference signal, a generating unit that generates a transmission signal used for transmitting the radio wave for the narrow area communication;
A wireless communication apparatus comprising: a supply unit capable of switching supply of the first reference signal to the conversion unit and supply of the second reference signal to the generation unit.
(2) The wireless communication device according to (1),
The converter converts the received signal to the intermediate frequency by mixing the first reference signal and the received signal,
The wireless communication apparatus, wherein the supply unit controls the frequency of the first reference signal so that the intermediate frequency is smaller than a frequency difference between the reception signal and the transmission signal.
(3) The wireless communication device according to (1) or (2),
The said communication part has a 1st internal filter which passes the frequency component of the 1st zone | band containing the said intermediate frequency, and regulates the frequency component which is not contained in the said 1st zone | band.
(4) The wireless communication device according to any one of (1) to (3),
The wireless communication apparatus, wherein the intermediate frequency has an absolute value of 2.2 MHz to 2.8 MHz.
(5) The wireless communication device according to any one of (1) to (4),
The intermediate frequency is a wireless communication device having an absolute value of approximately 2.5 MHz.
(6) The wireless communication device according to (1) or (2),
The wireless communication apparatus, wherein the supply unit controls the frequency of the first reference signal so that the intermediate frequency becomes substantially zero.
(7) The wireless communication device according to (6),
The said communication part is a radio | wireless communication apparatus which has a 2nd internal filter which passes the frequency component of the 2nd zone | band containing the said intermediate frequency, and regulates a frequency component higher than the upper limit frequency of the said 2nd zone | band.
(8) The wireless communication device according to any one of (1) to (7),
The supply unit includes a phase synchronization circuit capable of oscillating by switching between the first and second reference signals.
(9) The wireless communication device according to any one of (1) to (8),
The supply unit includes a frequency division unit that divides the frequency of the second reference signal by a predetermined ratio to generate a frequency division signal;
The said production | generation part is a radio | wireless communication apparatus which produces | generates the said transmission signal by performing the mixing of the said frequency division signal with respect to a baseband signal, and the mixing of a 2nd reference signal.
(10) The wireless communication device according to (9),
The predetermined ratio is any one of 1/2, 1/4, and 1/6.
(11) The wireless communication device according to any one of (1) to (10),
A wireless communication apparatus comprising: a signal generation unit that generates a data signal based on the intermediate frequency signal.
(12) The wireless communication device according to (11),
The wireless communication apparatus, wherein the data signal includes at least one of a QPSK signal, an ASK signal, and a carrier strength signal.
(13) The wireless communication device according to (11) or (12),
The radio communication apparatus, wherein the signal generation unit includes a digital filter unit that digitizes and filters the intermediate frequency signal, and a mixer unit that converts the output of the digital filter unit into a frequency for demodulation.
(14) The wireless communication device according to (13),
The digital filter unit and the mixer unit are wireless communication devices that operate based on a reference clock signal.
(15) The wireless communication device according to any one of (1) to (14),
The wireless communication apparatus, wherein the reception signal is a signal having a frequency lower than that of the transmission signal.
(16) The wireless communication device according to (15),
A wireless communication device configured as a vehicle-mounted device.

fi ... Intermediate frequency 10 ...

Communication unit

100, 200, 400, 500 ...

Wireless communication device

20, 420, 520 ...

Reception unit

22, 423 ... Orthogonal mixer 23 ... Band pass filter 24 ...

Low pass filter

30, 430 ...

Transmission unit

31, 431 ...

Modulator

40, 440 ...

Local oscillator

41, 441 ...

First reference signal

42, 442 ...

Second reference signal

51, 451 ... First

high frequency signal

52, 452 ... Second high frequency signal 458 ... Baseband Signal 462 ... Second divided signal 550 ... Data signal 556 ... ASK detection output 557 ... Carrier detection output 558 ... Output for QPSK 570 ... Signal generator 574 ... Quadrature mixer 582 ... System reference clock signal

Claims

A communication unit capable of transmitting and receiving radio waves for narrow area communication;
A conversion unit that converts a reception signal generated in response to reception of the radio wave for narrow area communication into an intermediate frequency based on a first reference signal;
Based on a second reference signal having a frequency different from that of the first reference signal, a generating unit that generates a transmission signal used for transmitting the radio wave for the narrow area communication;
A wireless communication apparatus comprising: a supply unit capable of switching supply of the first reference signal to the conversion unit and supply of the second reference signal to the generation unit.
The wireless communication device according to claim 1,
The converter converts the received signal to the intermediate frequency by mixing the first reference signal and the received signal,
The wireless communication apparatus, wherein the supply unit controls the frequency of the first reference signal so that the intermediate frequency is smaller than a frequency difference between the reception signal and the transmission signal.
The wireless communication device according to claim 1,
The said communication part has a 1st internal filter which passes the frequency component of the 1st zone | band containing the said intermediate frequency, and regulates the frequency component which is not contained in the said 1st zone | band.
The wireless communication device according to claim 1,
The wireless communication apparatus, wherein the intermediate frequency has an absolute value of 2.2 MHz to 2.8 MHz.
The wireless communication device according to claim 1,
The intermediate frequency is a wireless communication device having an absolute value of approximately 2.5 MHz.
The wireless communication device according to claim 1,
The wireless communication apparatus, wherein the supply unit controls the frequency of the first reference signal so that the intermediate frequency becomes substantially zero.
The wireless communication device according to claim 6,
The said communication part is a radio | wireless communication apparatus which has a 2nd internal filter which passes the frequency component of the 2nd zone | band containing the said intermediate frequency, and regulates a frequency component higher than the upper limit frequency of the said 2nd zone | band.
The wireless communication device according to claim 1,
The supply unit includes a phase synchronization circuit capable of oscillating by switching between the first and second reference signals.
The wireless communication device according to claim 1,
The supply unit includes a frequency division unit that divides the frequency of the second reference signal by a predetermined ratio to generate a frequency division signal;
The said production | generation part is a radio | wireless communication apparatus which produces | generates the said transmission signal by performing the mixing of the said frequency-divided signal with respect to a baseband signal, and the mixing of a 2nd reference signal.
The wireless communication device according to claim 9,
The predetermined ratio is any one of 1/2, 1/4, and 1/6.
The wireless communication device according to claim 1, further comprising:
A wireless communication apparatus comprising: a signal generation unit that generates a data signal based on the intermediate frequency signal.
The wireless communication device according to claim 11,
The wireless communication apparatus, wherein the data signal includes at least one of a QPSK signal, an ASK signal, and a carrier strength signal.
The wireless communication device according to claim 11,
The radio communication apparatus, wherein the signal generation unit includes a digital filter unit that digitizes and filters the intermediate frequency signal, and a mixer unit that converts the output of the digital filter unit into a frequency for demodulation.
The wireless communication device according to claim 13,
The digital filter unit and the mixer unit are wireless communication devices that operate based on a reference clock signal.
The wireless communication device according to claim 1,
The wireless communication apparatus, wherein the reception signal is a signal having a frequency lower than that of the transmission signal.
The wireless communication device according to claim 15, wherein
A wireless communication device configured as a vehicle-mounted device.
Send and receive radio waves for narrow area communication,
Based on the first reference signal, the received signal generated in response to the reception of the radio wave for narrow area communication is converted to an intermediate frequency,
Based on a second reference signal having a frequency different from that of the first reference signal, a transmission signal used to transmit the radio wave for the narrow area communication is generated,
A wireless communication method for switching between supply of the first reference signal and supply of the second reference signal.