JP5212045B2 - Wireless communication device and communication method - Google Patents

Description

  The present invention relates to a wireless communication device, and more particularly to a wireless communication device capable of supporting a plurality of wireless communication systems and a receiving method thereof.

  Recently, wireless devices using various wireless communication schemes have been widely spread, and depletion of frequency resources associated therewith has been regarded as a problem. However, for example, even in urban areas where wireless devices are thought to be flooded, it is said that 80% of the frequency is not used effectively at the moment in time and space. Research and development of cognitive radio that aims to provide users with high-speed data communication and stable communication services by making effective use of an unused license-free frequency band (white space spectrum) has been actively conducted.

  The cognitive radio is used for wireless communication according to the environment by providing a function for recognizing and cognitively confirming the state of wireless communication used in the vicinity of a terminal or base station used for wireless communication. The radio device itself selects communication parameters such as a communication method, a modulation method, a frequency, and a data rate, thereby increasing frequency use efficiency.

  Software radio or reconfigurable radio is currently considered as a promising means for realizing the cognitive radio.

  In software radio, signal transmission / reception is performed by general-purpose hardware, and the signal processing unit corresponding to the wireless communication system is configured by software. Various or new wireless communication can be performed by changing or updating the software. It is a radio that aims to be able to respond flexibly to the system.

  Reconfigurable radio expands the flexibility of software defined radio to middleware and communication units, and its configuration is generally performed by DSP (Digital Signal Processor) + FPGA (Field Programmable Gate Array). .

  Software defined radio is sometimes referred to as including reconfigurable radio. As shown in Non-Patent Document 1, software radio that does not include a hardware reconfiguration unit has not been realized at present.

Antonio Di Stefano, Giuseppe Fiscelli and Costantino G. Giaconia, “An FPGA-Based Software Defined Radio Platform for the 2.4GHz ISMBand”, Research in Microelectronics and Electronics 2006, Ph. D., pp. 73-76, June 2006

  The analysis according to the invention is given below.

  A so-called software defined radio including the radio disclosed in Non-Patent Document 1 takes time to reconfigure the hardware unit (in Non-Patent Document 1, about 3 seconds or less). For this reason, it is difficult to provide a user with multiple communications using a plurality of wireless communication systems.

  There is a possibility that the switching speed of the wireless communication standard can be improved by eliminating a portion that requires hardware reconfiguration.

  However, a software defined radio cannot be realized unless it is configured to include a hardware reconfiguration unit (a circuit element realized using an FPGA or the like). Therefore, in a software defined radio equipped with a hardware reconfiguration unit, it is difficult to switch radio communication methods within the shortest packet communication time.

  Also, paying attention to the time required for reconfiguration, it is possible to eliminate the reconfiguration time by preparing (multiplexing) multiple types of hardware in advance, but the hardware circuit scale increases. However, the circuit scale of the communication device, increase in power consumption, and the like become problems.

  An object of the present invention is to provide a wireless communication device, a system, and a communication method that speed up switching of wireless communication methods and suppress an increase in circuit scale when realizing communication using a plurality of wireless communication methods.

  The invention disclosed in the present application has the following configuration in order to solve the above-described problems.

  According to the present invention, the front end unit includes a front end unit that amplifies a received signal to perform frequency conversion and filter processing, and a baseband unit that performs demodulation and signal processing of the signal from the front end unit. In response to the switching signal, frequency bands corresponding to a plurality of communication systems are switched, and the baseband unit switches the plurality of communication systems in the front end unit in response to the switching signal. There is provided a wireless communication device that switches to demodulation processing of a communication system corresponding to the above.

According to the present invention, communication by a wireless communication device having a front end unit that amplifies a received signal, performs frequency conversion and filter processing, and a baseband unit that performs demodulation and signal processing of the signal from the front end unit A method,
In the front end unit, in response to the switching signal, the frequency band corresponding to each of the plurality of communication methods is switched,
In the baseband unit, a reception method is provided in which, in response to the switching signal, switching to a demodulation method of a communication method corresponding to switching of a plurality of communication methods in the front end unit is provided.

  According to the present invention, there is provided a wireless system including a communication terminal and a transmission station that wirelessly transmits a signal to the communication terminal, and the communication terminal includes the wireless communication device.

  ADVANTAGE OF THE INVENTION According to this invention, when implement | achieving communication using a some radio | wireless communication system, switching of a radio | wireless communication system can be speeded up and the increase in a circuit scale can be suppressed.

  First, the outline and basic principle of the present invention will be described. In the present invention, a front end unit (1) including an amplifier (101) for amplifying a received signal, frequency conversion circuits (102, 103), and a filter (104), a demodulation unit (106), and a signal processing unit ( 108), and in response to a switching signal (107), the front end unit switches frequency bands corresponding to a plurality of communication standards, and the baseband unit In response to the switching signal, the demodulating unit (106) performs switching to a demodulation method of a communication method corresponding to switching of a plurality of communication methods in the front end unit.

  The function of recognizing and cognitively communicating the status of wireless communication is not implemented as software defined radio or reconfigurable radio, but is implemented with a circuit that simplifies the search function for multiple communication methods, circuit scale, and processing By reducing the amount of calculation, it is possible to realize high speed and put it to practical use.

  According to the present invention, on the radio communication device side, the frequency band, the demodulation method, etc. are sequentially switched in a time-sharing manner according to the switching signal, and the communication method in which the data can be correctly demodulated becomes an effective communication method. Is also applicable. As a result, search latency can be reduced.

  The present invention can cope with a case where a transmitting station transmits a packet by a plurality of different communication standards or a plurality of channels by sequentially switching the frequency band, the demodulation method, and the like in a time division manner. For example, a plurality of wireless communication systems A, B, and C may be sequentially switched in the order of A → B → C → A → B → C. In this case, information regarding the time division switching order of communication schemes and the like may be exchanged (negotiation) between the transmitting station and the radio communication device before the start of radio transmission, and the communication scheme may be switched according to the information. . Time division switching may be performed on a packet basis. In the wireless communication device, a trigger signal for setting the switching signal to a value corresponding to the next communication method is generated when it is determined that the processing of one packet is completed in a signal processing unit (packet decomposition processing or the like) that processes demodulated data. You may do it.

  In the present invention, a communication device is realized in which characteristics inside a wireless device are switched by a switching signal, a carrier frequency and a communication bandwidth can be selected, and a plurality of wireless communication standards can be used. To provide a communication device that can provide a multiplex communication environment to the user by changing the characteristics of the radio device as much as possible to eliminate the factors that limit the time constant such as feedback and speeding up the switching time. Can do. Also, it is possible to configure with a small area by executing the characteristic change inside the radio device not by multiplexing circuits etc. but by element in block, element selection at circuit level (selection of valid / invalid) and combinations thereof. it can. The same effect can be obtained by switching at a higher level and control level than the circuit.

<Embodiment 1>
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a wireless communication device according to a first embodiment of this invention. FIG. 1 shows the configuration of a time division receiving unit in a wireless communication device. As shown in FIG. 1, the wireless communication apparatus of the present embodiment includes a variable bandwidth amplifier 101, a mixer 102, a local signal generator 103, a filter 104, an ADC (analog / digital converter) 105, and a demodulation unit 106. .

  The band variable amplifier 101 receives the received electrical signal and changes the band to be amplified by the switching signal 107. The mixer 102 multiplies the output signal (RF signal) of the band variable amplifier 101 by the local signal (local signal) from the local signal generator 103, and outputs an IF (intermediate frequency) signal from the filter (IF filter) 104. The ADC 105 converts an analog signal into a digital signal. The demodulator 106 receives the digital signal from the output of the ADC 105 and switches the demodulation process by the switching signal 107. The signal demodulated by the demodulation unit 106 is input to a signal processing unit (protocol processing unit) 108 to acquire data.

  The switching signal 107 changes the amplifiable band of the variable band amplifier 101 and the digital data extraction process in the demodulation unit 106 in a coordinated manner.

  By selecting a carrier wave band to be passed by the variable bandwidth amplifier 101 using the switching signal 107 and selecting a process for extracting desired digital data by the demodulator 106, it is possible to extract data corresponding to a specific communication method from the received signal. It becomes. By changing the characteristics of the receiver by the switching signal 107 between the RF unit (band variable amplifier) and the digital baseband unit, it contributes to the suppression of the amount of configuration change in each unit. The switching signal 107 is a binary logic signal to shorten the characteristic switching time.

  In the digital baseband unit 2, the signal processing unit 108 that processes the signal demodulated by the demodulation unit 106 determines whether or not communication is actually possible using the wireless communication method selected by the switching signal 107.

  For example, when the protocol processing of data for one packet is completed, the signal processing unit 108 may have a logical configuration that sets a completion signal and inverts (toggles) the value of the binary switching signal 107 based on the completion signal. Based on the data from the demodulator 106, the signal processor 108 disassembles the data for one packet into a header and a payload, and transmits the payload data to an upper layer processing device (not shown). When the processing for one packet is completed, the completion signal (Done flag) is activated, and the control logic (not shown) that outputs the switching signal 107 inverts the logic of the switching signal 107 in response to the activation of the completion signal. To do.

  According to the present embodiment, switching between wireless communication methods is shortened, and for example, it is possible to determine whether communication is possible or not within one packet period. In addition, it is possible to reduce the search latency of an effective communication method.

  Further, in cooperation with a transmitting station (not shown), the wireless communication systems A and B may be sequentially switched from A → B → A → B. At this time, it is necessary to share the order of the wireless communication systems to be switched in advance between the transmitter and the receiver. This can be realized by describing the order and timing of switching the wireless communication method in a time division manner in the negotiation between the transmitter and the receiver prior to transmission and reception of actual data.

  In this embodiment, it is needless to say that the setting (initial setting, forced reset, etc.) of the switching signal 107 may be performed based on an instruction from an external operation unit.

  FIG. 2 is a diagram showing an example of the configuration of the variable bandwidth amplifier 101 of FIG. Referring to FIG. 2, an amplification stage transistor (nMOS transistor) 201 whose source is connected to the ground and receives an input signal at the gate, and a bias stage transistor (source that is connected to the drain of the amplification stage transistor 201 and receives a bias signal at the gate) nMOS transistor) 202, an inductor (L1) 203 and a capacitor (C1) 204 connected in parallel between the drain of the bias stage transistor 202 and the power source, and a changeover switch between the terminals of the capacitor (C1) 204. A series circuit of 206 and a capacitor (C2) 205 is connected in parallel.

  The signal input to the variable band amplifier 101 shown in FIG. 2 is converted into a drain-source current from the signal that has been provided as the gate-source AC voltage amplitude in the amplification stage transistor 201. In voltage / current conversion, linearity is desirable. The degree to which the linearity should be maintained with respect to the input signal amplitude is determined from the system design according to the requirement from the communication standard, the circuit power consumption, the allowable value of the chip area, and the like. In the present specification, circuit constants and the like for a configuration specialized for a specific communication standard are omitted.

  The signal that has undergone voltage / current conversion in the amplification stage transistor 201 is adjusted to have a DC level suitable for output in the bias stage transistor 202, and an inductor 203, a capacitor 204, and a capacitor 204 connected in parallel between the bias stage transistor 202 and the power source. Together with the impedance of the load of the capacitor 205, the output amplitude is determined. That is, the output amplitude (amplification factor) can be determined by the impedance of the load. The changeover switch 206 receives a changeover signal 207 (corresponding to 107 in FIG. 1), is on / off controlled, and can change the impedance value of the load. The control of the load impedance will be described later.

<Embodiment 2>
Next, a second embodiment of the present invention will be described. FIG. 5 is a diagram showing the configuration of the second exemplary embodiment of the present invention. In FIG. 5, the signal processing unit is omitted. Hereinafter, differences from the first embodiment will be described, and description of the same parts will be omitted as appropriate in order to avoid duplication. The received signal is input to an LNA (Low-Noise Amplifier) 401 and amplified. The output signal of the LNA 401 is frequency-converted by the mixer 402 and input to the channel selection filter 400. A communication bandwidth is determined by the channel selection filter 400. The channel selection filter 400 includes a filter A404 connected between the output of the mixer 402 and the input of the ADC 407, and a changeover switch 406-1, a filter B405, and a changeover switch 406- connected between the output of the mixer 402 and the input of the ADC 407. 2 is provided. The changeover switches 406-1 and 406-2 are on / off controlled by a changeover signal 409, and the communication bandwidth is varied. The control of the communication bandwidth will be described later.

  The signal output from the channel selection filter 400 is demodulated in the demodulator 408 via the ADC 407. The switching signal 409 is input in common to the channel selection filter 400 and the demodulation unit 408. The channel selection filter 400 is switched to either the configuration of only the filter A 404 or the parallel configuration of the filter A 404 and the filter B 405 according to the value of the switching signal 409.

  In the present embodiment, data corresponding to a specific communication method can be extracted from received signals for communication methods having the same carrier band.

<Embodiment 3>
Next, a third embodiment of the present invention will be described. FIG. 7 is a diagram showing the configuration of the third exemplary embodiment of the present invention. In FIG. 7, the signal processing unit is omitted. The received signal is input to the LNA 601, and the signal output from the LNA 601 is converted into desired digital data from the mixer 602 by the filter 604, ADC 605, and demodulator 606.

  The mixer 602, the local signal generator 603, and the filter 604 constitute a pseudo-band variable filter 600, and a switching signal 607 is input. A communication bandwidth that can pass through the pseudo-band variable filter 600 is selected by the switching signal 607. The switching signal 607 is input in common to the pseudo-band variable filter 600 and the demodulator 606.

  In the present embodiment, data corresponding to a specific communication method can be extracted from signals received for a communication method having the same carrier band.

<Embodiment 4>
Next, a fourth embodiment of the present invention will be described. FIG. 9 is a diagram showing a configuration of the fourth exemplary embodiment of the present invention. The received signal is input to the LNA 801 and amplified, and the output signal of the LNA 801 is converted into desired digital data by passing through the sampling mixer 802, the sampling filter 803, the ADC 804, and the demodulator 805. The sampling mixer 802 samples a continuous-time analog signal (frequency fc) in response to a sampling clock (frequency fs) (accumulates charge in a capacitor) and converts the frequency into fc-fs (discrete time). -Time) Output an analog signal. The sampling mixer 802 and the sampling filter 803 are configured by an SCF (Switched Capacitor Filter) or the like. In the discrete processing system, the switching signal 807 is input only to the sampling clock generator 806, and the sampling clock generator 806 switches the sampling clock frequency based on the value of the switching signal 807. In the present embodiment, data corresponding to a specific communication method can be extracted from the received signal.

  As mentioned above, although the said embodiment was described for description of this invention, of course, this invention is not limited only to the structure of the said embodiment. Further, a configuration in which the above embodiments are combined, or a configuration in which processing is not shared between the RF unit and the digital baseband is possible. Hereinafter, description will be made with reference to examples.

<Example 1>
A first embodiment of the present invention will be described. This example is a specific example of the first embodiment described above, and its configuration is the same as that shown in FIGS. 1 and 2.

  FIG. 3 is a diagram illustrating frequency characteristics of the variable bandwidth amplifier. Hereinafter, an operation in the case where the two received signal bands are switched in time division by digital control will be described. Here, it is assumed that wireless communication standard A and wireless communication standard B having two different carrier frequencies are received.

  In the wireless communication standard A, the carrier band A is used, and in the wireless communication standard B, the carrier band B is used.

  The band of the received signal to be time-division switched is a carrier band A and a carrier band B, and the switching signal 107 is binary, ie, an active state (logic 1 or on) / inactive state (logic 0 or off). Shall. Note that the number of reception signal bands is not limited to two, and the switching signal 107 is not limited to ON / OFF. For example, in the case of switching of four communication methods, the switching signal takes four values. Although not particularly limited, in this embodiment, a signal received by an antenna (not shown) is subjected to reflection loss, generated thermal noise, and the like according to a request from the system design before being input to the variable bandwidth amplifier 101 in FIG. It shall be minimized as appropriate.

  The received signal input to the variable bandwidth amplifier 101 in FIG. 1 is converted into voltage / current in the amplification stage transistor 201 in FIG. 2, and the DC level is adjusted in the bias stage transistor 202, and the output signal is combined with the impedance of the load. The amplitude is determined.

  As shown in FIG. 2, the load is formed of an inductor 203, a capacitor 204, and a capacitor 205 arranged in parallel. Whether or not the capacitor 205 connects the output and the power source and contributes to the load impedance is determined by the activation and deactivation of the binary switching signal 207.

  Assume that when the switching signal 207 is active, the capacitor 205 is included in the load impedance, and when it is inactive, the electrical connection between the capacitor 205 and the power supply is cut off and is not included in the load impedance. When the switching signal 207 is in the active state, the load between the output and the power supply forms a parallel LC resonance circuit of the inductor 203, the capacitor 204, and the capacitor 205. The frequency at which the impedance is maximum is called the LC resonance frequency and is given by Equation (1).

  Since the gain (amplification factor) A of the variable bandwidth amplifier 101 is expressed by the product of the transconductance gm of the amplification stage transistor 201 and the load impedance Z, the variable bandwidth amplifier 101 has the gain at the LC resonance frequency of the equation (1). Has the maximum value.

  If the LC resonance frequency 1 / (2π√ (L1 (C1 + C2))) matches the frequency of the carrier band A, it is possible to selectively receive the signal of the carrier band A while removing the signal of the carrier band B. It becomes possible.

  Next, when the switching signal 207 is in an inactive state (off), the switching switch 206 is turned off, and the load between the output and the power supply forms a parallel LC resonance circuit including only the inductor 203 and the capacitor 204. At this time, the gain of the variable band amplifier 101 is maximized at the LC resonance frequency of Expression (2).

  If the LC resonance frequency 1 / (2π√ (L1 · C1)) and the frequency of the carrier band B coincide with each other, the signal of the carrier band B can be selectively received.

  FIG. 3 shows the carrier wave band selectivity in accordance with these switching signals 207. In FIG. 3, the carrier wave band A with the changeover switch turned on is a case where the changeover switch 206 in FIG. 2 is turned on, and the center frequency of the carrier wave band A is given by the equation (1). The carrier band B in which the changeover switch is off is a case where the changeover switch 206 in FIG. 2 is off, and the center frequency of the carrier band A is given by Equation (2).

  In the present embodiment, a configuration in which two amplifiers that pass the carrier band A and an amplifier that passes the carrier band B are juxtaposed is not adopted. In the present embodiment, this can be achieved by switching the resonance frequency of the load between the carrier band A and the carrier band B only by the on / off operation of the switching signal 107 (207). The part where the characteristic is variable is digital control, and there is no process including a time constant such as feedback. By setting the on / off operation speed of the switching signal 207 to a desired high speed, the frequency characteristics can be changed at a necessary speed.

  Since the LC circuit constituting the load has a basic filter configuration, the filter order is improved when there is a request to increase the number of received signal bands or to increase the selectivity of the carrier band B with respect to the carrier band A. Or by adding notches as appropriate. Also in this case, the frequency characteristic needs to be variable by the switching signal 207.

  Next, the signal output from the variable bandwidth amplifier 101 is multiplied by the local signal from the local signal generator 103 in the mixer 102, and the filter 104 removes components that interfere with demodulation, such as interference waves and image components. The The output of the filter 104 is converted from an analog signal to a digital signal in the ADC 105. In a series of processing flows from the input to the mixer 102 to the output of the ADC 105, the wireless communication standard A and the wireless communication standard B are not distinguished, and the circuit characteristics are not switched.

  In the description of the operation described above, the function of distinguishing between the communication standard A and the communication standard B is closed by the band variable amplifier 101, and the method is distinguished by the frequency of both the carrier band A and the carrier band B. The difference is made. However, it is not sufficient to distinguish between these carrier bands. In the wireless communication system, information such as a modulation system and a baseband frequency is included in the received signal in addition to the carrier band in the physical layer. In order to distinguish between them, it is necessary to distinguish information on modulation schemes and baseband frequencies. This distinction is performed by the demodulator 106. The baseband frequency is lower than the carrier frequency, and the modulation method can be distinguished by digital signal processing.

  For this reason, in the demodulation unit 106, the ADC output signals including the modulation scheme and baseband frequency information are distinguished into those according to the wireless communication standard A and those according to the wireless communication standard B in synchronization with the switching signal. To output digital data of each standard. Since this distinction is easy in digital signal processing, it may be performed by hardware or software processing.

  The digital data of the wireless communication standard A and the wireless communication standard B are synchronized with the switching of the value of the switching signal without passing through a part that regulates the switching speed specially for a plurality of communication standards received from the above series of operations. Digital data is obtained.

  According to the present embodiment, it is possible to perform switching and demodulation of the wireless communication system at high speed in a time division manner by eliminating the need for hardware reconfiguration that required the wireless communication system switching time. There is no need to prepare (multiplex) multiple pieces of hardware according to the wireless communication method, and the configuration of switching the carrier wave of the wireless communication method by switching the configuration of the load circuit increases the circuit scale while achieving high-speed switching. Can be configured.

  In other words, in the switching of the radio communication system in the receiver, the circuit corresponding to the standard for the carrier frequency is not combined in plural / parallel, but the characteristic is switched by the switching signal in the single circuit, and the demodulator A distinction is made.

  FIG. 4 is a diagram for explaining the front end unit 1 and the digital baseband unit 2 of FIG. Based on the switching signal 107, the front end unit 1 switches the band to the carrier band A (2.4 GHz) or the carrier band B (5 GHz) depending on whether or not the capacitor 205 of the load 200 of the band variable amplifier 101 is connected. Based on the switching signal 107, the demodulator 106 switches the demodulation method to, for example, FSK (Frequency Shift Keying) or PSK (Phase Shift Keying). A signal processing unit (protocol processing unit) 108 that receives demodulated data from the demodulating unit 106 determines whether communication using the current communication method is possible based on the presence / absence of errors in the demodulated data. When communication is possible, protocol processing is performed by analyzing header information of the received packet.

  In this embodiment, in the case of a method of switching wireless communication methods in a time division manner, for example, when it is determined that the processing for one packet has been completed, the communication processing unit (protocol processing unit) controls the reversal of switching of the switching signal. . The inverted switching signal is supplied to the LC load circuit and demodulation unit 106 of the variable bandwidth amplifier 101.

  In this embodiment, when switching communication methods in a time division manner, the communication method order is such that the communication method order information is included in the control information (for example, a common channel) transmitted from the transmitting station to the wireless communication device. Alternatively, in response to an inquiry from the radio base station, the transmission station may transmit the communication system order information individually (in an individual channel) to the radio communication device.

<Example 2>
Next, a second embodiment of the present invention will be described. This example is a specific example of the second embodiment of FIG. In the second embodiment of FIG. 5, the communication bandwidth is switched by the channel selection filter 400. In the following, an operation when the time division receiver switches between two received signal bands in a time division manner will be described. Assume that wireless communication standards A and B having two different communication bandwidths are received. The wireless communication standard A uses the communication band A, and the wireless communication standard B uses the communication band B. In the present embodiment, the number of communication bandwidths is set to 2 for the sake of simplicity of explanation, but it goes without saying that the number of communication bandwidths is not limited to 2 in the present invention.

  Since LNA 401 to mixer 402 are targeted for communication standard selection in the same carrier band, processing is performed without distinguishing between wireless communication standard A and wireless communication standard B, and circuit characteristics are not switched.

  As illustrated in FIG. 5, the channel selection filter 400 includes a filter A 404, a filter B 405, and switches 406-1 and 406-2. The filter A 404 and the filter B 405 may be configured using, for example, passive elements. Or you may comprise with the gm-C filter by OTA (Operational Transductance Amplifier) and a capacitor. The on / off of the changeover switches 406-1 and 406-2 is determined by the value of the changeover signal 409.

  When the switching signal 409 is active (logic 1), the switches 406-1 and 406-2 are turned on, the filter B405 is included in the signal path of the channel selection filter 400, and the switching signal 409 is inactive (logic 0). ), The filter B405 is cut off from the signal path. The bandwidth [fal, fh] of the filter A 404 and the bandwidth [fbl, fbh] of the filter B 405 are assumed to have the following relationship.

        fal ≦ fbl ≦ fah ≦ fbh (3)

  Note that the relationship between the bandwidths of the filter A 404 and the filter B 405 can be changed according to the desired communication standard, and is not limited to this relationship.

  First, when the switching signal 409 is in an inactive state, the channel selection filter 400 includes only the filter A404. Therefore, the communication bandwidth by the channel selection filter 400 is [fal to fah] (communication bandwidth by only the filter A in FIG. 6). By setting the frequency range [fal to fah] to coincide with the communication band A or to include the communication band A, it is possible to perform channel selection according to the wireless communication standard A.

  Next, when the switching signal 409 is in an active state (logic 1), the channel selection filter 400 includes a filter A 404 and a filter B 405 connected in parallel. As a result, the selection of the communication bandwidth by the channel selection filter 400 becomes the frequency range [fal to fbh] (communication bandwidth by the filter A + B in FIG. 6). By setting the frequency range [fal to fbh] to coincide with the communication band B or to include the communication band B, it is possible to perform channel selection according to the wireless communication standard B.

  As described above, the communication band A can be set by setting the value of the switching signal 409 in a small area without preparing the channel selection filters of the wireless communication standards A and B by the channel selection filter 400 as shown in FIG. And B can be selected.

  Furthermore, since the characteristics are switched by the switching signal 409 and there is no process including a time constant such as feedback, there is nothing that regulates the characteristics switching speed. For this reason, it is possible to change the channel selection at a necessary speed by setting the switching speed of the value of the switching signal 409 to a desired high speed. Increasing the number of communication band selections can be handled by adding filters.

  In FIG. 5, filters having different bandwidths are combined with the channel selection filter 400, but it is also possible to control the communication bandwidth of the channel selection filter by controlling the elements constituting the filter with the switching signal 409. Good. The demodulator 408 outputs desired digital data of the wireless communication standard A and the wireless communication standard B in synchronization with the switching signal 409.

  From the series of operations described above, the digital data of the wireless communication standard A and the wireless communication standard B of the wireless communication standard B can be synchronized with the switching of the value of the switching signal without passing through the part that regulates the switching speed for a plurality of wireless communication standards. Each digital data is obtained.

  In this embodiment, since the degree of freedom for setting the band of the filter is high, various communication bandwidths can be realized with a small circuit area.

<Example 3>
Next, a third embodiment of the present invention will be described. This example is a specific example of the third embodiment shown in FIG. 8A and 8B are diagrams for selecting a communication bandwidth by the pseudo-band variable filter 600 of FIG. Hereinafter, the operation when the time division receiver of FIG. 7 performs time division switching between two received signal bands by digital control will be described. As in the second embodiment, it is assumed that two wireless communication standards A and B having different communication bandwidths are received.

  First, since the LNA 601 targets communication standard selection in the same carrier band, processing is performed without distinguishing between the wireless communication standard A and the wireless communication standard B, and circuit characteristics are not switched. The mixer 602 multiplies the local signal from the local signal generator 603 and performs frequency conversion, and outputs an IF signal through the filter 604. At this time, the output frequency of the mixer 602 can be changed by changing the frequency of the local signal (local frequency) according to the value of the switching signal 607.

  Normally, the output frequency band of the mixer 602 and the pass band of the filter 604 are set so as to be equal or nearly equal, but in this embodiment, they are not matched. As a result, the pseudo-band variable filter 600 can be formed by the mixer 602, the local signal generator 603, and the filter 604.

  The same effect can be obtained even if the frequency of the local signal is fixed and the pass band of the filter 604 is changed. The same applies when changing the frequency of the filter and the local signal. In this embodiment, it is assumed that the passband (frequency characteristic) of the filter 604 is constant and the local signal frequency is changed by the switching signal 607. The pass band of the filter 604 is set to fl to fh (fl ≦ fh).

  First, when the switching signal 607 is in an active state (logic 1), the output frequency band of the mixer 602 is assumed to be [fal to fah] by the local signal. At this time, the signal band that can pass through the filter 604 is [fal to fh] (see the hatched communication bandwidth A in FIG. 8A). By setting [fal to fh] to coincide with the communication band A or to include the communication bandwidth A, channel selection according to the wireless communication standard A can be performed.

  Next, when the switching signal 607 is in an inactive state (logic 0), the output frequency band of the mixer 602 is assumed to be [fbl to fbh] by the local signal. At this time, the signal band that can pass through the filter 604 is [fbl to fh] (see the hatched communication bandwidth B in FIG. 8B). By setting [fbl to fh] to coincide with the communication band B or to include the communication band B, channel selection according to the wireless communication standard B can be performed.

  As described above, according to the present embodiment, it is unnecessary to prepare a channel selection filter for each of the wireless communication standards A and B by switching the transmission frequency of the local signal. Further, since the oscillation frequency of the local signal can be changed by simple control, the communication bandwidth A and the communication bandwidth B can be selected only by the on / off operation of the switching signal in a small area.

  Therefore, it goes without saying that it is easy to cope with cases where the number of selected communication bands is further increased. Further, the filter characteristic need not be a band pass filter, and the relationship between the frequency bands is not limited to the above description.

  The demodulator 606 outputs desired digital data of the wireless communication standard A and the wireless communication standard B in synchronization with the switching signal. With respect to a plurality of communication standards received from the above series of operations, digital data of wireless communication standard A and digital data of wireless communication standard B are obtained in synchronization with switching of the value of the switching signal. In the present embodiment, it can be realized with reduced area overhead.

<Example 4>
Next, a fourth embodiment of the present invention will be described. This example is a specific example of the fourth embodiment shown in FIG. In the following, the operation when the receiver of FIG. 9 performs time division switching between two received signal bands by digital control will be described. The configuration in FIG. 9 is a discrete processing system as described above. At this time, the sampling mixer 802, the sampling filter 803, the ADC 804, and the demodulator 805 are driven by the sampling clock from the sampling clock generator 806, and change the characteristics (frequency characteristics) of each circuit block according to the frequency of the sampling clock. be able to.

  As an example, the frequency characteristics of the sampling mixer 802 will be described. In the following, as in the first embodiment, the case where two wireless communication standards A and B having different carrier frequencies are received will be described. The sampling clock frequency input to the sampling mixer 802 determines the operation of the sampling mixer 802. That is, it is shown that the bandwidth of the input signal can be limited by the sampling clock frequency.

  Assume that the sampling clock frequency can be switched between fa and fb by activation (logic 1) / inactivation (logic 0) of the switching signal 807. Although the present embodiment will be described assuming that there are two communication bands, of course, in the present invention, the selectable communication bands are not limited to these two.

  Since the sampling mixer 802 is a mixing operation of an input signal and a sampling clock, when the sampling clock frequency is fa or fb, the carrier band selectivity similar to that in FIG. 3 is obtained. That is, if the sampling clock frequency is changed by the switching signal 807, the carrier frequency can be selected according to the frequency characteristics of the sampling mixer 802.

  In this embodiment, since the receiver is a discrete processing system, the characteristics of each block element can be changed by changing the sampling clock by the switching signal 807. Therefore, the design overhead of the elements required for switching is suppressed, and the area overhead is also suppressed. It is possible.

  In the above embodiment, the wireless communication device may be applied to a receiving device such as a medium-range communication such as a wireless LAN (Local Area Network) or a short-range communication such as Bluetooth. Alternatively, the wireless communication device may be configured as a mobile terminal (for example, a cellular terminal) that receives a wireless signal from the base station.

  Each disclosure of the above non-patent document is incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Various combinations and selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea.

It is a figure which shows the structure of the 1st Example of this invention. FIG. 2 is a diagram illustrating the configuration of the variable bandwidth amplifier of FIG. 1 with an equivalent circuit. It is a figure which shows the frequency characteristic of the band variable amplifier of FIG. It is a figure which shows the operation example of the 1st Example of this invention. It is a figure which shows the structure of the 2nd Example of this invention. It is a figure explaining selection of the communication bandwidth by the filter of FIG. It is a figure which shows the structure of the 3rd Example of this invention. It is a figure explaining selection of the communication bandwidth by the pseudo band variable filter of FIG. It is a figure which shows the structure of the 4th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front end part 2 Digital baseband part 101 Band variable amplifier 102 Mixer 103 Local signal generator 104 Filter 105 ADC
106 Demodulator 107 Switching Signal 200 Load 201 Amplifying Stage Transistor 202 Bias Stage Transistor 203 Inductor 204 Capacitance (C1)
205 capacity (C2)
206 changeover switch 207 changeover signal 400 channel selection filter 401 LNA
402 Mixer 403 Local signal generator 404 Filter A
405 Filter B
406-1, 406-2 changeover switch 407 ADC
408 Demodulator 409 Switching signal 600 Pseudo-band variable filter 601 LNA
602 mixer 603 local signal generation period 604 filter 605 ADC
606 Demodulator 607 Switching signal 801 LNA
802 Sampling mixer 803 Sampling filter 804 ADC
805 Demodulator 806 Sampling clock generator 807 Switching signal

Claims (18)

A front-end unit that amplifies the received signal and performs frequency conversion and filter processing;
A baseband unit that performs demodulation and signal processing of a signal from the front end unit;
With
In the front end unit, in response to the switching signal, the frequency band corresponding to each of the plurality of communication methods is switched,
In the baseband unit, the demodulation unit, in response to said switching signal, have rows switching to demodulation processing of the communication system corresponding to the switching of the plurality of communication methods at the front end portion,
The switching to be supplied to the front end unit and the demodulating unit in response to a completion signal that is activated when processing of data of a predetermined unit is completed by a signal processing unit that performs signal processing on the data demodulated by the demodulating unit A wireless communication device , wherein a signal is set to a value corresponding to the next communication method, and a plurality of communication methods are switched in a time-sharing manner . When the signal processing unit determines that the protocol processing of one packet data is completed, the signal processing unit activates the completion signal, and sets the switching signal supplied to the front end unit and the demodulation unit to a value corresponding to the next communication method. The wireless communication device according to claim 1, wherein the wireless communication device is set. The front end portion is
An amplifier whose band is varied by the switching signal;
A filter circuit whose frequency characteristics are varied by the switching signal;
A frequency conversion circuit in which the frequency of the local signal is varied by the switching signal;
And it has a wireless communication apparatus according to claim 1 or 2, characterized in that with any of the. The front end unit includes an amplifier whose band is changed by the switching signal,
4. The wireless communication device according to claim 3 , wherein the amplifier varies a capacitance of an LC circuit that forms a load of a transistor that is cascade-connected to the amplification stage and the bias stage by the switching signal. The front end unit includes a filter circuit whose passband is changed by the switching signal,
The filter circuit is
Multiple filters with different frequency characteristics,
With
By the switching signal,
A plurality of filters connected in parallel and frequency-converted signals are commonly input to the plurality of filters, or
Separating at least one of the plurality of filters from a signal line of the filter circuit and inputting the frequency-converted signal to the remaining filters;
4. The wireless communication device according to claim 3 , wherein switching to any one of the connection forms is performed. The front end unit includes a frequency conversion circuit whose local frequency is varied by the switching signal,
The frequency conversion circuit includes a local signal generator whose local frequency is changed by the switching signal, and a mixer that mixes an output of the amplifier with a local signal from the local signal generator. Item 4. A wireless communication device according to item 3 . The front end portion is
A sampling mixer;
A sampling filter;
With
Said sampling mixer, giving a sampling clock to said sampling filter, and analog-to-digital converter for converting the analog output of the sampling filter into a digital signal, a sampling clock generator providing a clock to said demodulating portion of the base band section Prepared,
4. The wireless communication device according to claim 3, wherein the sampling clock generator varies a sampling clock and a frequency of the clock according to the switching signal. Wherein by sequentially changing the value of the switching signal, a plurality of communication systems, time division, sequentially switched, the wireless communication apparatus according to any one of claims 1 to 7, characterized in that. A communication method by a wireless communication device having a front end unit that amplifies a received signal and performs frequency conversion and filter processing, and a baseband unit that performs demodulation and signal processing of the signal from the front end unit,
In the front end unit, in response to the switching signal, the frequency band corresponding to each of the plurality of communication methods is switched,
In the baseband unit, the demodulation unit, in response to said switching signal, have rows switching to demodulation processing of the communication system corresponding to the switching of the plurality of communication methods at the front end portion,
The switching to be supplied to the front end unit and the demodulating unit in response to a completion signal that is activated when processing of data of a predetermined unit is completed by a signal processing unit that performs signal processing on the data demodulated by the demodulating unit A communication method, wherein a signal is set to a value corresponding to the next communication method, and a plurality of communication methods are switched in a time division manner. When the signal processing unit determines that the protocol processing of one packet data is completed, the signal processing unit activates the completion signal, and sets the switching signal supplied to the front end unit and the demodulation unit to a value corresponding to the next communication method. The communication method according to claim 9, wherein the communication method is set . In the front end portion,
The band of the amplifier is varied by the switching signal.
The pass band of the filter circuit is varied by the switching signal.
By the switching signal, the frequency of the local signal of the frequency conversion circuit is varied.
The communication method according to claim 9 or 10, wherein any one of the above is performed.   12. The communication method according to claim 11, wherein, in the front end unit, a capacitance of an LC circuit forming a load of a transistor that is two-stage cascode connected to an amplification stage and a bias stage is varied by the switching signal. In the front end portion, the filter circuit has a plurality of filters,
By the switching signal,
A plurality of filters connected in parallel and frequency-converted signals are commonly input to the plurality of filters, or
Separating at least one of the plurality of filters from a signal line of the filter circuit and inputting the frequency-converted signal to the remaining filters;
The communication method according to claim 11, wherein switching to any one of the connection forms is performed. In the front end portion, the local frequency is varied by the switching signal,
The communication method according to claim 11, wherein the frequency conversion circuit mixes an output of the amplifier with a local signal. In the front end unit, an analog-to-digital converter that varies a sampling mixer and a sampling clock frequency applied to a sampling filter by the switching signal, and converts an analog output of the sampling filter into a digital signal by the switching signal; The communication method according to claim 11, wherein a frequency of a clock applied to the demodulation unit of the baseband unit is varied.   The communication method according to any one of claims 10 to 15, wherein a plurality of communication methods are sequentially switched in a time division manner by sequentially changing the value of the switching signal. A communication terminal;
A transmitting station for wirelessly transmitting a signal to the communication terminal;
With
Wherein the communication terminal includes a wireless communication device according to any one of claims 1 to 8, a wireless system. The wireless system according to claim 17 , wherein the transmitting station switches a communication method in a time division manner.

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