JP2023123099A - Processing device to transmit analog signal to wireless device - Google Patents

Abstract

To provide a technique for transmitting control information to a wireless device with a simple configuration.SOLUTION: A processing device transmits an analog signal to a wireless device that generates a wireless signal on the basis of the analog signal and transmits it. The processing device includes control means for generating a pulse signal that conveys control information to the wireless device and a low-pass filter that restricts the maximum frequency of the pulse signal, multiplexing means for multiplexing the pulse signal that has passed through the low-pass filter and the analog signal and outputting a multiplexed signal, and modulation means for generating modulated light by modulating carrier light with the multiplexing signal and transmitting the modulated light to the wireless device.SELECTED DRAWING: Figure 3

Description

The present invention relates to a technology for transmitting analog signals for generating wireless signals to wireless devices that transmit and receive wireless signals through optical fibers.

FIG. 1 divides the functions of a base station device of a mobile communication network into a processing device 1 and a radio device 2. The radio device 2 is arranged at an antenna site 200 where an antenna is installed, and the processing device 1 is arranged at an antenna site 200. 1 shows a configuration arranged at an accommodation site 100 that is geographically different from . The radio equipment 2 has a function of transmitting/receiving radio signals to/from a radio device (WD) or user equipment (UE) of a mobile communication network via an antenna, and a function of processing the radio signals. On the other hand, the processing device 1 has a function of processing baseband signals of radio signals transmitted and received by the radio device 2 . The processing device 1 and the wireless device 2 are connected by an optical transmission line 3 including an optical fiber.

Non-Patent Document 1 discloses CPRI, which is a communication interface between the processing device 1 and the wireless device 2 . Specifically, the processing device 1 samples the signal waveform of the baseband signal and transmits the sampled values to the wireless device 2 as digital values. In CPRI, the control information transmitted from the processing device 1 to the wireless device 2 is time-division multiplexed with digital values indicating sampling values. At present, CPRI transmission is becoming inefficient due to an increase in transmission capacity to WD.

CPRI Specific V7.0, October 9, 2015

In order to cope with the increase in transmission capacity to the WD, the processing device 1 generates an IF signal in the intermediate frequency (IF) band or an RF signal in the radio frequency (RF) band from the baseband signal, and converts the IF signal or the RF signal A configuration is conceivable in which the modulated light generated by modulating the carrier light is transmitted to the wireless device 2 . The radio device 2 demodulates the modulated light to restore/generate the IF signal or RF signal transmitted by the processing device 1, converts these signals into radio signals of a predetermined frequency in the radio frequency band, and then performs amplification and the like. are processed and output from the antenna. Note that frequency conversion can be omitted if the frequency of the RF signal matches the predetermined frequency.

FIG. 2 shows the frequency components of an exemplary modulated light produced by processing device 1 in such a configuration. According to FIG. 2, the modulated light carries four frequency multiplexed IF signals 81-84. Here, if another optical transmission line 3 is used for transmitting and receiving control information between the processing device 1 and the wireless device 2, the configuration becomes complicated and the cost increases.

The present invention provides technology for transmitting control information to a wireless device with a simple configuration.

According to one aspect of the present invention, to a wireless device that generates and transmits a wireless signal based on an analog signal, the processing device that transmits the analog signal controls to generate a pulse signal that carries control information to the wireless device. combining means for combining the pulse signal and the analog signal that have passed through the low-pass filter and outputting a combined signal; modulating means for generating modulated light by modulating carrier light with a signal and transmitting the modulated light to the wireless device.

According to the present invention, it is possible to transmit control information to a wireless device with a simple configuration.

FIG. 2 illustrates a base station system consisting of two devices located at different geographical locations; FIG. 2 shows the frequency components of modulated light in the system of FIG. 1; 1 is a configuration diagram of a base station system including a processing device and a radio device according to one embodiment; FIG. FIG. 4 shows the frequency components of the modulated light of the system of FIG. 3; 1 is a configuration diagram of a base station system including a processing device and a radio device according to one embodiment; FIG. 1 is a configuration diagram of a base station system including a processing device and a radio device according to one embodiment; FIG.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined arbitrarily. Also, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

<First embodiment>
FIG. 3 is a configuration diagram of a base station system including a processing device 1 and a radio device 2 according to this embodiment. The control unit 10 controls the processing device 1 and generates a control signal to be transmitted to the wireless device 2 . The control signal is a signal carrying control information, and in this embodiment the control signal is a digital signal, ie a pulse signal. For example, the control signal may be a signal conforming to standards used in local area networks (LANs). The pulse signal can be a Non-Return-to-Zero (NRZ) signal or a Return-to-Zero (RZ) signal. At the same transmission speed, the NRZ signal is preferable because the NRZ signal has a narrower bandwidth than the RZ signal. The control unit 10 outputs the control signal to the low-pass filter (LPF) 11 of the multiplexing unit 13 . The LPF 11 has a passband below the threshold frequency f1 and limits the frequency band of the control signal. A high-pass filter (HPF) 12 of the combining unit 13 receives an IF signal or an RF signal carrying information to be transmitted to the WD, or a frequency-multiplexed signal obtained by frequency-multiplexing them. An IF signal, an RF signal, or a frequency-multiplexed signal obtained by frequency-multiplexing them is an analog signal. "analog signal". The lowest frequency of the analog signal is set to be higher than the threshold frequency f1. The HPF 12 suppresses unnecessary frequency components below the threshold frequency f1.

The combining unit 13 outputs a combined signal obtained by combining the filtered control signal and the analog signal to the modulation unit 14 . The modulation unit 14 generates modulated light by modulating the carrier light with the combined signal, and transmits the modulated light to the wireless device 2 . FIG. 4 shows frequency components of modulated light. Reference numerals 81-84 in FIG. 4 are all analog signals, and reference numerals 81-84 respectively correspond to four IF signals. Reference number 80 in FIG. 4 corresponds to a control signal.

The demodulator 24 demodulates the modulated light received from the processor 1 and outputs a combined signal to the separator 23 . After separating the multiplexed signal, the separation unit 23 outputs a control signal through the LPF 21 and an analog signal through the HPF 22 . The passbands of LPF21 and HPF22 are similar to those of LPF11 and HPF12, respectively. The control unit 20 receives a control signal from the LPF 21 and controls the wireless device 2 based on the control signal. An analog signal output from the HPF 22 is converted into a radio signal by a circuit (not shown) and transmitted to the WD.

As described above, in the present embodiment, the control signal, which is a pulse signal for controlling the wireless device 20, and the analog signal carrying information to be transmitted to the WD are multiplexed, and the carrier light is modulated with the multiplexed signal. and transmits it to the wireless device 20 . This configuration allows control signals and analog signals to be transmitted over the same optical fiber. In addition, since the control information is transmitted as a baseband signal (for example, NRZ pulse signal) without modulating the electrical signal of the sine wave carrier (for example, ASK, PSK, QAM, etc.) based on the control information, the control information is A configuration for transmission can be simplified. The configuration in the direction from the wireless device 2 to the processing device 1 is the same. can be used.

<Second embodiment>
Next, the second embodiment will be described, focusing on differences from the first embodiment. For example, when the data amount of control information to be transmitted to the wireless device 2 increases, such as when the wireless device 2 is installed, the time required to transmit the control signal to the wireless device 2 increases with a bandwidth less than the threshold frequency f1. Therefore, in this embodiment, the threshold frequency is made variable according to the amount of control information to be transmitted, that is, the transmission speed required for the control signal.

FIG. 5 is a configuration diagram of the processing device 1 and the wireless device 2 according to this embodiment. Components similar to those in FIG. 3 of the first embodiment are denoted by the same reference numerals, and differences will be mainly described below. The control section 10 also outputs the control signal to the LPF 15 of the multiplexing section 17 . The LPF 15 has a passband below the threshold frequency f2 and suppresses unnecessary high frequency components. Note that the threshold frequency f2 is greater than the threshold frequency f1. The analog signal is also input to the HPF 16 of the combining section 17 . The HPF 16 suppresses unnecessary frequency components below the threshold frequency f2.
The combining unit 17 combines the filtered control signal and the analog signal to generate a combined signal.

The multiplexed signal from the multiplexer 13 and the multiplexed signal from the multiplexer 17 are input to the selector 18 . While the control unit 10 transmits the first control signal capable of limiting the maximum frequency to less than the threshold frequency f1, the control unit 10 controls the selection unit 18 to output the multiplexed signal from the multiplexing unit 13 to the modulation unit 14. Let On the other hand, the control unit 10 controls the selection unit 18 while transmitting the second control signal that requires the maximum frequency to be higher than the threshold frequency f1, but can be limited to less than the threshold frequency f2. The multiplexed signal from the wave section 17 is output to the modulation section 14 . For example, the first control signal may be 100MbE and the second control signal may be 1GbE.

Further, the control unit 10 instructs the wireless device 2 by the first control signal to set the first switching timing for switching from the first control signal to the second control signal at a predetermined timing before switching from the first control signal to the second control signal. Notice. Similarly, the control unit 10 sets the second switching timing for switching from the second control signal to the first control signal at a predetermined timing before switching from the second control signal to the first control signal, using the second control signal. to notify. At the first switching timing, the control unit 20 of the wireless device 2 controls the selection unit 28 to output the multiplexed signal output from the demodulation unit 24 to the separation unit 27 . Also, at the second switching timing, the control section 20 controls the selection section 28 to output the multiplexed signal output from the demodulation section 24 to the separation section 23 . The separation unit 27 outputs the second control signal to the control unit 20 via the LPF 25 and outputs an analog signal via the HPF 26 . The passbands of LPF25 and HPF26 are similar to those of LPF15 and HPF16, respectively.

Note that while using the second control signal, less bandwidth is available for analog signals. Therefore, the control unit 10 limits the amount of information transmitted to the WD and reduces the bandwidth of the analog signal while the second control signal is being used. Also, in the present embodiment, two multiplexing units including LPFs and HPFs are used, but three or more multiplexing units may be used. The LPF and HPF passbands of the three or more multiplexing units are different, and the control unit 10 selects the multiplexing unit that outputs the multiplexed signal to the modulation unit 14 according to the speed of the control signal to be transmitted. . Note that the multiplexing unit to be selected is selected from multiplexing units having LPFs having the maximum frequency required for transmission of the control signal within the passband. For example, the multiplexing unit to be selected may be the multiplexing unit having the lowest passband LPF among the multiplexing units having an LPF whose passband contains the maximum frequency required for transmission of the control signal.

As described above, according to this embodiment, when the amount of information to be transmitted increases, the speed of the control signal can be increased.

<Third embodiment>
Next, the third embodiment will be described, focusing on differences from the second embodiment. In the second embodiment, two or more multiplexers including LPF and HPF are used so that the speed of the control signal can be increased. In this embodiment, one multiplexing unit is used.

FIG. 6 is a block diagram of the processing device 1 and wireless device 2 according to this embodiment. The control unit 10 also outputs the control signal to the selection unit 18 . While the control unit 10 transmits the first control signal capable of limiting the maximum frequency to less than the threshold frequency f1, the control unit 10 controls the selection unit 18 to output the multiplexed signal from the multiplexing unit 13 to the modulation unit 14. Let On the other hand, while the control unit 10 is transmitting the third control signal whose maximum frequency cannot be limited to less than the threshold frequency f1, the control unit 10 controls the selection unit 18 to output the control signal from the control unit 10 to the modulation unit 14. .

Further, the control unit 10 notifies the control unit 20 of the switching timing between the first control signal and the third control signal, as in the second embodiment. Therefore, the first control signal is input from the selector 28 to the controller 20 via the separator 23 , and the third control signal is directly input from the selector 28 to the controller 20 .

Note that unlike the second embodiment, while the third control signal is being used, the control unit 10 temporarily stops transmission to the WD and does not transmit analog signals. In many cases, the amount of information in the control signal increases during the period in which a link is established between the processing device and the wireless device before starting transmission and reception of wireless signals (including when rebooting). By limiting the functions described above, desired effects can be obtained with a simpler configuration than the second embodiment.

<Fourth embodiment>
In this embodiment, the control signal is used to measure the quality of the optical transmission line 3 from the processing device 1 to the wireless device 2 and determine the quality of the analog signal carried on the optical transmission line 3 . Specifically, the control unit 10 transmits known pattern data to the control unit 20 by a control signal, and the control unit 20 determines whether or not an error has occurred based on the known pattern data. The signal-to-noise ratio (SN ratio) of the optical transmission line 3 from the processing device 1 to the wireless device 2 can be determined by measuring the known pattern while changing the level of the carrier light.

With the above configuration, the control signal can be transmitted to the wireless device with a simple configuration. Therefore, it will be possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

13: Multiplexer, 14: Modulator

Claims (7)

A processing device that transmits the analog signal to a radio device that generates and transmits a radio signal based on the analog signal,
control means for generating a pulse signal carrying control information to said wireless device;
combining means for combining the pulse signal passed through the low-pass filter and the analog signal and outputting a combined signal;
modulating means for generating modulated light by modulating carrier light with the multiplexed signal and transmitting the modulated light to the wireless device;
A processing unit, comprising: selecting means for receiving the combined signal and the pulse signal and outputting either the combined signal or the pulse signal to the modulating means;
The control means controls the selection means so that the combined signal is output to the modulation means when the maximum frequency required for transmission of the pulse signal is within the passband of the low-pass filter, and the pulse signal 2. The processor according to claim 1, controlling said selection means so that said pulse signal is output to said modulation means when the maximum frequency required for signal transmission is outside the passband of said low-pass filter. a plurality of multiplexing means;
selecting means for outputting one of the multiplexed signals from the multiplexing means to the modulating means;
with
The passbands of the low-pass filters of the plurality of multiplexing means are different,
2. The processing apparatus according to claim 1, wherein said control means selects said one combined signal output by said selection means to said modulation means according to a maximum frequency required for transmission of said pulse signal. The control means selects one multiplexing means from one or more first multiplexing means including the low-pass filter having the passband of the maximum frequency necessary for transmitting the pulse signal among the multiple multiplexing means. 4. The processor of claim 3, wherein selecting means selects the one combined signal. 5. The processing apparatus according to claim 4, wherein said one multiplexing means is a first multiplexing means comprising said low-pass filter having the lowest pass band among said one or more first multiplexing means. 6. The processing device according to any one of claims 1 to 5, wherein said control means controls the bandwidth of said analog signal according to the maximum frequency required for transmission of said pulse signal. 7. The control means according to any one of claims 1 to 6, wherein said control means transmits predetermined data in said pulse signal in order to measure transmission quality on an optical transmission line from said processing device to said wireless device. processing equipment.

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