Wireless communication device, inverse characteristic calculation method, and program

Abstract

To reduce the deterioration of transmission characteristics caused by the frequency characteristics of a wireless communication device when the bandwidth of an information signal is widened.SOLUTION: A wireless communication device according to the disclosed technique includes a transmission signal processing unit that processes a baseband signal to generate a wireless signal to be transmitted from an antenna, and a transmission compensation unit that calculates the inverse characteristic of the frequency characteristic of the transmission signal processing unit on the baseband signal. The wireless communication device also includes a reception signal processing unit that processes a wireless signal received by the antenna to generate a baseband signal, and a reception compensation unit that calculates the inverse characteristic of the frequency characteristic of the reception signal processing unit on the baseband signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosed technology relates to a wireless communication device that transmits and receives wideband information signals, and more specifically to a technology for reducing intersymbol interference caused by the frequency characteristics of a transmitting device and a receiving device. [Background technology]

[0002] Studies on the sixth-generation mobile communication system (hereinafter referred to as "6G") have begun. One of the requirements for 6G is ultra-high speeds exceeding 100 Gbps. One method for achieving this requirement is to widen the signal bandwidth. When the signal bandwidth increases by L times, the communication channel capacity derived from the Shannon-Hartley theorem also increases by L times. The fifth-generation mobile communication system (hereinafter referred to as "5G") also aims to widen the signal band compared to the fourth-generation mobile communication system (hereinafter referred to as "4G"). The maximum signal bandwidth of 4G (carrier frequency 10 GHz or less) was 10 MHz, but in 5G, the signal bandwidth has been expanded to a maximum of 100 MHz for carrier frequencies 6 GHz or less, and to a maximum of 400 MHz for carrier frequencies above 6 GHz (Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP (registered trademark), "5G System Overview", Aug 08, 2022, [Retrieved December 22, 2023], Internet<https: / / www.3gpp.org / technologies / 5g-system-overview> . Summary of the Invention [Problem to be solved by the invention]

[0004] In wireless communications, it is desirable that the frequency spectrum of the transmitted signal sent from the transmitting device and the received signal received by the receiving device match the frequency spectrum of the transmitted information signal. However, when the information signal is processed by the transmitting device and the receiving device, the frequency characteristics of each device affect the frequency spectrum of the processed signal, and the frequency spectrum of the processed signal may have a shape different from the frequency spectrum of the original information signal.

[0005] Generally, the frequency characteristics of a device fluctuate more significantly as the bandwidth of the signal being processed increases. Therefore, the wider the bandwidth of the information signal, the greater the change in the shape of the frequency spectrum. When the shape of the frequency spectrum changes, inter-symbol interference (ISI) occurs in the transmitted signal, and large ISI can cause code errors in the receiving device. That is, with wideband signals, degradation of transmission characteristics due to the frequency characteristics of wireless communication devices becomes a major problem. [Means for solving the problem]

[0006] The disclosed technology provides a wireless communication device that solves the above-mentioned problems. The wireless communication device according to the disclosed technology includes a transmission signal processing unit that processes a baseband signal to generate a radio signal to be transmitted from an antenna, and a transmission compensation unit that calculates the inverse frequency characteristic of the transmission signal processing unit on the baseband signal. In addition, the wireless communication device according to the disclosed technology includes a receiving signal processing unit that processes a wireless signal received by an antenna to generate a baseband signal, and a receiving compensation unit that calculates the inverse characteristics of the frequency characteristics of the receiving signal processing unit to generate a baseband signal. [Effects of the Invention]

[0007] According to the disclosed technology, the frequency characteristics of each of the transmission signal processing unit and the reception signal processing unit can be compensated for, so that deterioration of transmission characteristics caused by the frequency characteristics of the wireless communication device can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a functional block diagram of the wireless communication device according to the first embodiment. [Figure 2] FIG. 4 is a flowchart illustrating the operation of the wireless communication device according to the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating the principle of frequency characteristic compensation during transmission. [Figure 4] FIG. 2 is a diagram for explaining the principle of frequency characteristic compensation during reception. [Figure 5] FIG. 10 is a functional block diagram of a wireless communication device according to a second embodiment. [Figure 6] FIG. 10 is a functional block diagram of a wireless communication device according to a third embodiment. [Figure 7] FIG. 2 is a diagram showing an example of the functional configuration of a computer. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the disclosed technology will be described in detail. Note that components having the same functions are assigned the same numbers, and redundant explanations will be omitted.

[0010] [Frequency characteristic compensation principle] First, the principle of frequency characteristic compensation using the disclosed technology will be explained using Figures 3 and 4. <Frequency spectrum notation> Let's say the frequency spectrum of a baseband signal is F(ω), where ω is the angular frequency. If you upconvert the baseband signal using a local oscillator with frequency f2, you get a frequency spectrum αF(ω+2πf2), where α is a coefficient associated with the conversion. In this specification, for simplicity, the frequency spectrum of the baseband signal is expressed as F(ω B ), the frequency spectrum of the signal upconverted to the radio frequency band is F(ω RF ) is written as follows.

[0011] <Transmitter: Without compensation> The frequency spectrum of the baseband signal is S(ω B ) (Figure 3(a)). The transmission signal processing unit converts the baseband signal into a transmission signal in the radio frequency band. RF ) (Figure 3(b)). Then, the frequency spectrum of the transmission signal changes from the shape (original shape) of Figure 3(a) to the shape (Gtx(ω RF )S(ω RF ) into an undesired shape.

[0012] <Transmitter: Compensated> Gtx(ω B ) and the opposite frequency characteristics of G -1 tx(ω B ) in the frequency spectrum of the baseband signal in the transmission frequency characteristic compensation section. -1 tx(ω B ) is applied to eliminate the deformation to the undesired shape (Fig. 3(e)). As explained above in <Transmitter: No compensation>, the frequency spectrum is S(ω B ) will be explained as an example of processing a baseband signal (Fig. 3(d)). The frequency spectrum of the signal input to the transmission signal processing section is transformed by the function of the transmission frequency characteristic compensation section. -1 tx(ω B )S(ω B ) (Figure 3(f)). Then, the frequency spectrum of the output signal from the transmission signal processing unit is Gtx(ω RF )[G -1 tx(ω RF )S(ω RF )]=S(ω RF ) (FIG. 3(h)), and the change in the spectrum shape caused by the frequency characteristics of the transmission signal processing section is compensated for.

[0013] <Receiver: Without compensation> The frequency spectrum of the received signal is R(ω RF ) (Figure 4(a)). The receiving signal processing unit converts the received signal in the radio frequency band into a baseband signal. B) (Figure 4(b)). Then, the frequency spectrum of the received signal changes from the shape (original shape) of Fig. 4(a) to the shape (Grx(ω B )R(ω B ) into an undesired shape.

[0014] <Receiver: Compensated> Grx(ω B ) and the opposite frequency characteristics of G -1 rx(ω B ) in the frequency spectrum of the baseband signal in the receiving frequency characteristic compensation section. -1 rx(ω B ) is applied to eliminate the deformation to the undesired shape (Fig. 4(g)). Same as the explanation above for <Receiver: No compensation>, the frequency spectrum is R(ω RF ) is processed by the receiving signal processing unit (Fig. 4(d)). At this stage, the frequency spectrum of the output signal from the receiving signal processing unit is the same as that in Fig. 4(c), and Grx(ω B )R(ω B ) (Figure 4(f)). However, due to the function of the receiver frequency characteristic compensation section, the frequency spectrum of the output signal from the receiver frequency characteristic compensation section is G -1 rx(ω B )[Grx(ω B )R(ω B )]=R(ω B ) (FIG. 3(h)), and the change in the spectrum shape caused by the frequency characteristics of the receiving signal processing section is compensated for.

[0015] This concludes the explanation of the principle of frequency characteristic compensation. [Example]

[0016] FIG. 1 is a functional block diagram illustrating a configuration example of a wireless communication device according to a first embodiment. The wireless communication device 1 includes a transmitter 101 , a known signal generator 106 , a receiver 111 , and an antenna 131 .

[0017] The transmitting unit 101 includes a modulating unit 102, a transmitting compensation unit 103, a transmitting frequency conversion unit 104, and a transmitting radio signal processing unit 105. The transmitting frequency conversion unit 104 and the transmitting radio signal processing unit 105 together correspond to the transmitting signal processing unit described in [Principle of frequency characteristic compensation].

[0018] The receiving unit 111 includes a demodulating unit 112, a receiving compensation unit 113, a receiving frequency conversion unit 114, and a receiving radio signal processing unit 115. The receiving frequency conversion unit 114 and the receiving radio signal processing unit 115 together correspond to the receiving signal processing unit described in [Principle of frequency characteristic compensation].

[0019] In the wireless communication device 1, the functions of the modulation section / demodulation section, transmission / reception frequency conversion section, transmission / reception radio signal processing section, and antenna are the same as those of a conventional wireless communication device.

[0020] The modulation unit 102 generates a modulated signal in the baseband frequency band from the input data sequence. The transmission frequency converter 104 up-converts the modulated signal in the baseband frequency band to a radio frequency band. The transmission radio signal processing unit 105 amplifies the transmission signal in the radio frequency band and also suppresses out-of-band signals generated by frequency conversion by filtering. The antenna 131 emits a radio frequency band transmission signal into space and receives a radio frequency band reception signal from space. The receiving radio signal processing unit 115 amplifies the received signal in the radio frequency band and also suppresses out-of-band signals and signals in other frequency bands by filtering. The reception frequency converter 114 down-converts the received signal in the radio frequency band to the baseband frequency band. The demodulation unit 112 demodulates the received signal in the baseband frequency band and generates a demodulated signal (output data sequence).

[0021] FIG. 2 is a flowchart illustrating the operation of the wireless communication device 1 (particularly, the procedure for obtaining the inverse characteristic of the frequency characteristic). The first embodiment will be described in detail below with reference to FIGS.

[0022] [Frequency characteristic compensation setting] <Transmission compensation section> The known signal generator 106 generates a time domain signal sB(t) whose frequency spectrum is known, and inputs it to the transmitter 101 (step S201). B ) The transmission signal processing unit (series connection of the transmission frequency conversion unit 104 and the transmission radio signal processing unit 105) processes sB(t) in the time domain and converts it into a transmission signal sRF(t) (step S202). The frequency spectrum of sRF(t) is S2(ω RF ) and the frequency characteristics of the transmission signal processing unit are Gtx(ω RF )given that,

number

[0023] In addition, S1(ω RF ) and Gtx(ω RF )S1(ω RF ) to G -1 tx(ω RF) are generally well known, for example, there are algorithms that apply an algorithm that minimizes the mean square of the error of the sampled data in the time domain.

[0024] <Reception compensation section> The shape of the frequency spectrum of a received signal is generally unpredictable because it is affected by the propagation path, etc. Therefore, even if a known signal spectrum is provided as a cheat signal from the opposing wireless device, the frequency characteristics of the receiver cannot be compensated for unless the frequency characteristics of the propagation path are accurately understood. Once the setting of the transmission compensation section is complete, the frequency characteristics of the output of the transmission section are compensated. Therefore, a known signal spectrum with compensated frequency characteristics is input to the reception section to set the reception compensation section.

[0025] The known signal generator 106 generates a time domain signal sB(t) whose frequency spectrum shape is known, and inputs it to the transmitter 101 (step S206). The known frequency spectrum is S1(ω B ) The transmission compensation unit 103 converts sB(t) into a frequency domain signal S1(ω B ) and convert it to S1(ω B ) to G -1 tx(ω B ) (step S207). -1 tx(ω B )S1(ω B ) into a time domain signal s'B(t). The transmission signal processing unit processes s'B(t) and outputs s'RF(t) (step S208). The frequency characteristic of the transmission signal processing unit is Gtx(ω RF ), so the frequency spectrum of s'RF(t) is S1(ω RF )

[0026] s′RF(t) is input from the transmitter 101 to the receiver 111. The receiver signal processor (a serial connection of the receiver radio signal processor 115 and the receiver frequency converter 114) processes s′RF(t) and outputs a baseband signal s″B(t) (step S209). The frequency spectrum of s''B(t) is S3(ω B ) and the frequency characteristics of the receiving signal processing section are Grx(ω B )given that,

number

[0027] This concludes the explanation of [Setting the frequency characteristic compensation section].

[0028] [Communication Implementation] <Send> The modulator 102 modulates the input data stream to generate a time-domain baseband signal. The transmission compensation unit 103 converts the time domain baseband signal into the frequency domain, -1 tx(ω B ) into a frequency domain baseband signal. The transmission compensation unit 103 converts the frequency domain signal after the calculation into a time domain signal and outputs it. The transmission signal processing unit processes the output of the transmission compensation unit 103 to generate a radio frequency band signal. Antenna 131 emits the output of transmitter 101 into space.

[0029] <Receive> The antenna 131 receives a reception signal from space and outputs it to the receiving unit 111 . The received signal processing unit processes the radio frequency band signal to generate a time domain baseband signal. The receiver compensation unit 113 converts the time domain baseband signal into the frequency domain, -1 rx(ω B ) into a frequency domain baseband signal. Reception compensation section 103 converts the frequency domain signal after the calculation into a time domain signal and outputs it. Demodulation section 112 demodulates the output of reception compensation section 103 and outputs a data string.

[0030] [Update of frequency characteristic compensation section] The frequency characteristics of a communication device depend on the temperature of the communication device, so the inverse characteristic values set in the transmission / reception compensation units are updated periodically, for example, about once a day. The update procedure is the same as in [Setting of frequency characteristic compensation unit] above.

[0031] The above is the description of the first embodiment. [Example]

[0032] The transmitter and receiver are used simultaneously in the setting of the transmission / reception compensator described in the first embodiment. Therefore, in wireless communication in which the transmitter and receiver operate simultaneously (for example, frequency division duplex), communication must be stopped when setting / updating the compensator. However, in time division duplexing, which alternates between the transmitter and receiver, the compensation section can be set / updated for each transmission timing. This will be explained below.

[0033] 5 is a functional block diagram illustrating a configuration example of a wireless communication device according to a second embodiment, which differs from FIG. Switch 122 turns on / off the connection between transmitter output unit 124 and antenna 131. Switch 123 turns on / off the connection between receiver input unit 125 and antenna 131. Switch 121 turns on / off the connection between transmitter output unit 124 and receiver input unit 125.

[0034] At the transmission timing, the wireless communication device 5 turns on the switches 121 and 122 and turns off the switch 123. As explained in the first embodiment, the known signal generator transmits the known signal twice. The first known signal sets or updates the inverse characteristics of the transmission signal processing section in transmission compensation section 103. Then, the second known signal sets or updates the inverse characteristics of the reception signal processing section in reception compensation section 113. Alternatively, the first known signal may be used before communication starts to set or update the inverse characteristics of the transmission signal processing section in transmission compensation section 103. Thereafter, the input data string is processed by the transmission compensation unit 103 while communication is performed.

[0035] At the reception timing, the wireless communication device 5 turns off the switches 121 and 122 and turns on the switch 123, and performs communication while processing the received signal in the reception compensation section.

[0036] The above is the description of the second embodiment. [Example]

[0037] Regarding the application of the disclosed technology to time division duplex, in the second embodiment, a switch is used to supply a known signal whose frequency characteristics have been compensated from a transmitter to a receiver at the transmission timing. However, instead of a switch, a distributor may be used to supply a known signal whose frequency characteristics have been compensated from a transmitter to a receiver. This will be explained below.

[0038] 6 is a functional block diagram illustrating a configuration example of a wireless communication device according to a third embodiment, which differs from FIG. 1 in that a transmission signal distributor 601 and a reception signal combiner 602 are further provided. A portion of the transmission signal is distributed in transmission signal distributor 601. Since transmission signals generally have high power, a coupler with a small coupling coefficient is used, and the transmission signal is input and output at a pass-through port, and only a small portion of the transmission power is extracted from the coupled port.

[0039] The transmit signal extracted by transmit signal splitter 601 is input to receive signal combiner 602. Receive signal combiner 602 uses a coupler with a low coupling coefficient to achieve low insertion loss for the receive signal, which is a very small amount of power received by the antenna. The receive signal is input and output at the pass-through port, and the transmit signal is input to the receiving system from the coupled port. For example, if a 30 dB coupler is used, in the case of a transmit power of 30 dBm, 0 dBm of power is split by transmit signal splitter 601 and input to the receiving device at -30 dBm. Since the lower the degree of coupling, the smaller the loss of the pass-through signal is, so the receiver can use a coupler with a lower degree of coupling, or provide an attenuator at the input of the coupled port of receive signal combiner 602 to adjust the signal input level to the receiving device.

[0040] The wireless device shown in Fig. 6 switches between transmission and reception in units of time slots, and compensates for the frequency characteristics of the receiving device while radiating a transmission signal from an antenna at the transmission timing. On the other hand, at the reception timing, the receiving frequency characteristic compensation is performed on the received signal.

[0041] This concludes the description of the third embodiment.

[0042] [supplement] In the above embodiment, the inverse characteristics of the receiving section are calculated using a known signal obtained by calculating the inverse characteristics of the transmitting signal processing section in the transmitting compensation section, and then using a signal (compensated known signal) that has been subjected to processing such as up-conversion in the transmitting signal processing section. However, the wireless communication device may be configured so that the known signal is directly input to the receiving signal processing section to calculate the inverse characteristics of the receiving signal processing section.

[0043] [Programs, recording media] The functions performed by the components described herein may be implemented in circuitry or processing circuitry, including general-purpose processors, application-specific processors, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to perform the described functions. A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may also be a programmed processor that executes programs stored in memory.

[0044] In this specification, a circuitry, unit, or means is hardware that is programmed to realize or performs the described functions, which may be any hardware disclosed herein or any hardware known to be programmed to realize or perform the described functions.

[0045] If the hardware is a processor considered to be a type of circuitry, the circuitry, means, or unit is a combination of the hardware and software used to configure the hardware and / or processor.

[0046] The various processes described above can be implemented by loading a program that executes each step of the above method into the recording unit 2020 of the computer 2000 shown in Figure 7, and operating the control unit 2010, input unit 2030, output unit 2040, display unit 2050, etc.

[0047] The program describing the processing contents can be recorded on a computer-readable recording medium, which may be, for example, a magnetic recording device, an optical disk, a magneto-optical recording medium, a semiconductor memory, or any other suitable recording medium.

[0048] The program may be distributed, for example, by selling, transferring, lending, etc. a portable recording medium such as a DVD or CD-ROM on which the program is recorded. Furthermore, the program may be stored in a storage device of a server computer, and then transferred from the server computer to another computer via a network, thereby distributing the program.

[0049] A computer that executes such a program may first temporarily store the program recorded on a portable recording medium or transferred from a server computer in its own storage device. Then, when executing a process, the computer reads the program stored on its own recording medium and executes the process in accordance with the read program. Alternatively, the computer may read the program directly from a portable recording medium and execute the process in accordance with the program. Furthermore, the computer may execute the process in accordance with the program each time a program is transferred from a server computer to the computer. The server computer may not transfer the program to the computer, but may instead execute the process through a so-called ASP (Application Service Provider) service, which realizes the processing function by issuing an execution instruction and obtaining the results. Furthermore, the server computer may execute the process on a terminal using a so-called SaaS (Software as a Service) service, which allows users to use part of the server computer along with the program. In this embodiment, the program includes information used for computer processing that is equivalent to a program (such as data that is not a direct instruction to the computer but has properties that define computer processing).

[0050] Furthermore, in this embodiment, the device is configured by executing a predetermined program on a computer, but at least a part of the processing contents may be realized by hardware. [Explanation of symbols]

[0051] 1,5,6 Wireless communication devices 101 Transmitter 102 Modulation section 103 Transmission compensation section 104 Transmitting frequency conversion unit 105 Transmitting radio signal processing section 106 Known signal generator 111 Receiving unit 112 Demodulation section 113 Reception compensation section 114 Receiving frequency conversion unit 115 Receiving radio signal processing unit 121,122,123 Switch 131 Antenna 601 Transmission signal distributor 602 Received signal combiner 2000 Computer 2010 Control Unit 2020 Records Department 2030 Input section 2040 Output Unit 2050 Display section

Claims

1. a transmission signal processing unit that processes the baseband signal to generate a radio signal to be transmitted from an antenna; a transmission compensation unit that calculates an inverse characteristic of the frequency characteristic of the transmission signal processing unit on the baseband signal; A wireless communication device comprising:

2. a received signal processing unit that processes a radio signal received by an antenna to generate a baseband signal; a reception compensation unit that calculates an inverse characteristic of the frequency characteristic of the reception signal processing unit on the baseband signal; A wireless communication device comprising:

3. a transmission signal processing unit that processes the baseband signal to generate a radio signal to be transmitted from an antenna; a known signal generator that generates a known signal having a known frequency spectrum shape; the known signal generation unit obtains an inverse characteristic (first inverse characteristic) of the frequency characteristic of the transmission signal processing unit from the known signal and the known signal processed by the transmission signal processing unit; the transmission compensation unit generates a compensated signal by calculating the first inverse characteristic on a baseband signal obtained by modulating input data; The transmission signal processing unit processes the compensated signal to generate the radio signal. Wireless communication device.

4. 4. The wireless communication device according to claim 3, a received signal processing unit that processes the radio signal received by the antenna to generate a baseband signal; a reception compensation unit; a signal obtained by calculating the first inverse characteristic on the known signal and processing the signal by the transmission signal processing unit as a compensated known signal; the known signal generation unit obtains an inverse characteristic (second inverse characteristic) of the frequency characteristic of the received signal processing unit from the known signal and the compensated known signal processed by the received signal processing unit; the received signal processing unit processes the radio signal received by the antenna to generate a received baseband signal; The reception compensation unit calculates the second inverse characteristic on the reception baseband signal to generate a compensated reception signal. Wireless communication device.

5. 5. The wireless communication device according to claim 4, The first inverse characteristic and the second inverse characteristic are obtained at the transmission timing of time division duplex. A wireless communication device comprising:

6. 6. The wireless communication device according to claim 5, a switch for inputting the output of the transmission signal processing unit to the reception signal processing unit at the transmission timing of the time division duplex transmission; A wireless communication device comprising:

7. 6. The wireless communication device according to claim 5, A path for inputting a part of the output of the transmission signal processing unit to the reception signal processing unit. A wireless communication device comprising:

8. A method for obtaining an inverse characteristic of a frequency characteristic of a transmission signal processing unit of a wireless communication device, comprising: comparing a known signal with the known signal processed by the transmission signal processing unit to estimate a frequency characteristic (first frequency characteristic) of the transmission signal processing unit; Estimating an inverse characteristic (first inverse characteristic) of the first frequency characteristic Inverse characteristic calculation method.

9. A method for obtaining an inverse characteristic of a frequency characteristic of a reception signal processing unit of a wireless communication device using the first inverse characteristic according to claim 8, comprising: a signal obtained by calculating the first inverse characteristic on the known signal and processing the signal by the transmission signal processing unit as a compensated known signal; comparing the known signal with the compensated known signal processed by the received signal processing unit to estimate a frequency characteristic (second frequency characteristic) of the received signal processing unit; Estimating an inverse characteristic of the second frequency characteristic Inverse characteristic calculation method.

10. A program for causing a computer to execute the method according to claim 8 or 9.

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