JP2012156633A - Radio communication device and radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication device that can adequately detect absence of signal in a transmission signal and quickly perform adequate processing.SOLUTION: A remote radio unit (RRU) 3 according to the invention is given a transmission signal in which a preamble section including a preamble signal is periodically placed by a base band unit (BBU) 2. The RRU 3 comprises a second determination unit 49 for determining whether or not there is absence of signal in the transmission signal based on a correlation value obtained from an acquisition signal acquired from the preamble section.

Description

  The present invention relates to a radio communication apparatus such as a remote radio unit and a radio communication system using the same.

In recent years, a configuration in which a baseband signal processing unit and a wireless communication unit are separated is increasing as a wireless communication system such as a wireless base station device. The wireless communication unit is installed immediately below the antenna, and the baseband signal processing unit is installed at a position away from the wireless communication unit. The baseband signal processing unit and the wireless communication unit are connected by a line using a transmission path such as an optical fiber.
The wireless communication unit is called a remote radio unit (RRU). Note that the remote radio unit is sometimes called a remote radio head (RRH; Remote Radio Head).
A device having a baseband signal processing unit and other functions is called a baseband unit (BBU) (see, for example, Patent Document 1).

  As a connection interface between the baseband unit and the remote radio head, standards such as CPRI (Common Public Radio Interface) and OBSAI (Open Base Station Standard Initiative) have been established. In lines using these connection interfaces, in addition to a channel for baseband IQ signals, an Ethernet (registered trademark) channel can be logically set.

JP2009-077252

In the wireless communication system, when a data signal (transmission signal) to be wirelessly transmitted is transmitted between the BBU and the RRU, a LOS (Loss Of Signal) or LOF (Los Of Frame) is used on a line connecting the two. In some cases, a lack of signal in the transmission signal occurs.
When a lack of signal occurs in the transmission signal, it interferes with wireless communication. Therefore, it is necessary to detect the lack of signal and perform appropriate processing promptly.

  When the transmission signal lack occurs in a line connecting BBU and RRU, it may be difficult to detect on the BBU side. Therefore, it is appropriate to detect and process on the RRU side.

  The RRU usually uses a CDR (Clock Data Recovery) circuit having a function of recovering an operation clock synchronized with the BBU from a transmission signal transmitted from the BBU, and each device of the own apparatus using the recovered clock recovered by the CDR circuit. And a PLL for generating a supply clock for supplying the signal.

The CDR circuit detects the timing synchronized with the BBU obtained from the transmission signal, and adjusts the reproduction clock so that the phase of this timing is synchronized with the phase of the supply clock generated by the PLL, thereby operating the BBU operation clock. It is configured to be able to supply a clock synchronized with the.
The CDR circuit cannot obtain the synchronization timing based on the reference transmission signal when the transmission signal completely disappears or the signal absence state continues for a certain period, and cannot maintain the synchronization state. In this case, a synchronization error (out of lock) with the supply clock occurs.

  Therefore, the RRU causes the CDR circuit to detect the occurrence of synchronization deviation (out of lock) between the synchronization timing and the supply clock, so that the transmission signal is not transmitted at all or the signal absence state continues for a certain period. Can be detected.

  However, when the transmission signal does not completely disappear and the signal lack occurs intermittently, there is a possibility that synchronization is maintained in the CDR circuit and the lack of signal is not detected.

  Further, in order to perform appropriate processing promptly after the absence of a signal is detected, it is desirable that the RRU makes an independent determination and performs appropriate processing.

  The present invention has been made in view of such circumstances, and provides a wireless communication apparatus that can appropriately detect a lack of signal in a transmission signal and can quickly perform appropriate processing, and a wireless communication system using the same. The purpose is to do.

(1) The present invention is a wireless communication apparatus in which a transmission signal in which sections including a known signal are periodically arranged is provided from a baseband processing apparatus, and based on a detection result of the known signal in the transmission signal And a determination unit for determining the presence or absence of a signal lack in the transmission signal.

According to the radio base station apparatus having the above configuration, the determination unit determines the presence or absence of signal in the transmission signal based on the detection result of the known signal periodically arranged in the transmission signal. The presence or absence of a signal can be determined at regular intervals.
As a result, even if the signal lack occurs intermittently in the transmission signal, it is possible to appropriately detect the signal lack in the transmission signal by periodically determining the presence or absence of the signal lack.

(2) In the radio base station apparatus, a signal acquisition unit that acquires a signal included in the section of the transmission signal, and a correlation value based on the acquisition signal acquired by the signal acquisition unit are known in the transmission signal. It is preferable that a correlation value calculation unit obtained as a signal detection result is further included, and the determination unit determines whether or not there is a signal deficiency in the transmission signal based on the correlation value obtained by the correlation value calculation unit.
Here, the correlation value calculation unit obtains a correlation value between the reference signal for determining whether or not the known signal is included in the acquired signal and the acquired signal acquired by the signal acquiring unit. . This reference signal may be another acquired signal different from the acquired signal acquired by the signal acquiring unit, or may be a known signal stored in advance.
When the reference signal is another acquisition signal different from the acquisition signal acquired by the signal acquisition unit, the acquisition signal and the other acquisition signal include one signal and the other signal includes a known signal. A reference signal for determining whether or not the signal is present.

(3) In addition, the wireless communication device may have a function for compensating for distortion occurring in the input / output characteristics of the amplifier.
That is, in the wireless communication apparatus, an amplifier that receives the transmission signal as an input signal and outputs the amplified transmission signal as an output signal, and a distortion compensation unit that compensates for distortion occurring in input / output characteristics of the amplifier, The signal acquisition unit acquires a signal included in the section of the input signal and a signal included in the section of the output signal, and supplies the signal to the correlation value calculation unit and the distortion compensation unit. It may be a thing.

  According to the above configuration, the signal acquisition unit acquires the input signal and output signal of the amplifier necessary for the distortion compensation unit to perform distortion compensation of the amplifier, and the correlation value calculation unit calculates the correlation value using these input / output signals. Therefore, the determination unit and the distortion compensation unit can be used as a signal acquisition unit, and the apparatus scale can be reduced.

(4) Further, the correlation value calculation unit may obtain a correlation value using two acquired signals acquired from different sections. In this case, a high correlation value is obtained if the two acquired signals both contain a known signal, and a low correlation value is obtained if either or both do not contain a known signal (due to lack of signal). It is done. As described above, the correlation value calculation unit can obtain the correlation value as a detection result of the presence or absence of a known signal in the transmission signal.

(5) The wireless communication device further includes a storage unit for storing the known signal, and the correlation value calculation unit is stored in advance in the acquisition signal acquired by the signal acquisition unit and in the storage unit. Alternatively, a correlation value with the known signal may be obtained.
In this case, if an acquisition signal is acquired from the section, a correlation value with a known signal stored in advance can be obtained, and the presence or absence of a signal in the transmission signal can be determined. As a result, the process related to determination is simplified.

(6) In the wireless communication device, the signal acquisition unit acquires a signal included in the section of the transmission signal at a predetermined time interval, and when the correlation value is smaller than a predetermined first threshold, The signal acquisition unit may further include means for performing control to reduce the time interval for acquiring the acquisition signal.For example, the first threshold value can be clearly determined that the acquisition signal does not include a known signal. If the transmission unit is set to a value that can determine that a signal lack is present, the determination unit determines that the signal lack is present in the transmission signal. Even if there is a lack of signal in the transmission signal, it is possible to reliably determine the presence or absence of the signal.

(7) In addition, the determination unit may determine the presence or absence of signal in the transmission signal as a degree based on the number of times that the correlation value is determined to be smaller than a predetermined second threshold. Good.
More specifically, when the correlation value is smaller than the second threshold, the determination unit obtains, as a frequency, the number of times that the correlation value is determined to be smaller than the second threshold during a past certain period, and the frequency In response to this, it is also possible to determine the degree of signal absence in the transmission signal.
In the above configuration, for example, if the second threshold is set to a value that is determined to be a lack of transmission by clearly determining that the acquired signal does not include a known signal, the determination unit may It is possible to determine the frequency at which it is determined that the lack of signal has occurred, and based on this frequency, the lack of signal in the transmission signal can be determined as a degree. Further, by determining the lack of signal as a degree, it is possible to more suitably perform processing for the lack of signal.

If the frequency is extremely low, it is not recognized that the lack of signal in the transmission signal is intermittently generated. Therefore, the determination unit is when the frequency is smaller than a predetermined threshold value (threshold value F _Th1 ). The transmission signal may be determined to have no signal lack.
Even if it is not recognized that the lack of signal of the transmission signal occurs intermittently, it is possible that the lack of signal may occur. Therefore, since the frequency is smaller than the predetermined threshold (threshold value F _Th1 ), the lack of signal If there is no, it is preferable that the determination unit further includes means for leaving a log regarding the determination.
In this case, even if the frequency of signal loss is small, it is determined that a signal loss has occurred. Therefore, it is possible to perform preventive processing by leaving a log regarding this determination.

(8) The determination unit determines whether the signal lack is a mild signal lack or a severe signal lack, and determines that the signal lack is a slight signal lack, the baseband processing device A means for performing a warning notification and / or recording a log of this determination, and a means for stopping transmission of the transmission signal and / or restarting the own apparatus when it is determined that the signal is severely absent. Are preferably further provided.
In this case, it is possible to quickly perform a suitable process according to the degree of lack of the transmission signal based on the determination on the wireless communication apparatus side.

More specifically, the determination unit determines whether the frequency is equal to or higher than the predetermined threshold (threshold value F _Th1 ) and is greater than the predetermined threshold value (threshold value F _Th2 ). May be configured to determine that the transmission signal has a slight signal lack, and in this case, if the determination unit determines that the transmission signal has a slight signal lack, A warning can be notified to the processing device and / or a log of this determination can be recorded.

On the other hand, when the frequency is equal to or higher than the other predetermined threshold (threshold value F _Th2 ), the determination unit may be configured to determine that the transmission signal has a severe signal loss. When the determination unit determines that the transmission signal is severely lacking, it is possible to stop transmission of the transmission signal and / or restart the device itself.
As described above, according to the above configuration, it is possible to quickly perform a suitable process according to the degree of lack of transmission signals based on the determination on the wireless communication apparatus side.

(9) In the wireless communication device, it is preferable that the determination unit determines that there is no signal loss in the transmission signal when the correlation value is equal to or greater than a predetermined third threshold value.
In the above case, since the correlation value may be a value close to the third threshold value and it may be determined that there is no signal lack, the correlation value is a value that can be determined that the preset transmission signal has no signal lack. When the determination unit determines that the threshold value is less than a fourth threshold value that is greater than or equal to the third threshold value that is greater than the third threshold value, further includes means for leaving a log regarding this determination. May be.
In this case, even if it is determined that there is no lack of signal in the transmission signal, preventive processing can be performed by leaving a log regarding the determination.

(10) Further, the present invention provides a wireless communication system including a baseband processing device and a wireless communication device to which a transmission signal in which sections including known signals are periodically arranged is given from the baseband processing device. And the said radio | wireless communication apparatus is provided with the determination part which determines the presence or absence of the signal lack in the said transmission signal based on the detection result of the known signal in the said transmission signal.
According to the wireless communication system having the above configuration, as described above, it is possible to appropriately detect the lack of signal in the transmission signal, and it is possible to quickly perform appropriate processing.

  According to the wireless communication device and the wireless communication system of the present invention, it is possible to appropriately detect the lack of signal in the transmission signal, and it is possible to quickly perform appropriate processing.

It is a block diagram which shows the radio base station apparatus as an example of a radio | wireless communications system. It is a figure which shows the structure of the radio | wireless frame of WiMAX. It is a block diagram which shows the structure of the radio | wireless processing part of RRU3. It is a block diagram which shows the structure of the transmission signal process part which concerns on 1st embodiment. It is a figure for demonstrating the aspect in which both signal acquisition parts acquire the signal contained in a preamble area as an acquisition signal based on a frame timing signal. It is a figure for demonstrating the relationship between the signal lack which arises in a transmission signal, and the correlation value between a 1st acquisition signal and a 2nd acquisition signal, (a) is because transmission signal is transmitted normally. When each of the input signal and the output signal is normal, (b) is caused by the occurrence of LOF in the transmission signal, and when the LOF is caused in the output signal, (c) is input due to the occurrence of LOF in the transmission signal. The aspect of the input signal and output signal when LOF has occurred in both the signal and the output signal is shown. It is a flowchart which shows the signal lack determination process of the transmission signal which a 2nd determination part performs. It is a block diagram which shows the structure of the transmission signal process part which concerns on 2nd embodiment. It is a block diagram which shows the structure of the transmission signal process part which concerns on 3rd embodiment. It is a block diagram which shows the structure of the transmission signal process part which concerns on 4th embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[1. Configuration of communication system]
FIG. 1 is a block diagram showing a radio base station apparatus 1 as an example of a radio communication system. The wireless base station device 1 is a device to which a terminal device such as a mobile phone is wirelessly connected. The radio base station apparatus 1 is a system including a baseband unit (hereinafter sometimes simply referred to as “BBU”) 2 and a remote radio unit (hereinafter also simply referred to as “RRU”) 3. is there. In addition, this radio base station apparatus 1 is configured to perform radio communication conforming to WiMAX, for example.

FIG. 2 is a diagram illustrating the structure of a WiMAX radio frame. As shown in the figure, in WiMAX, a plurality of radio frames are arranged side by side in the time direction. One radio frame is configured to include a downlink subframe DL (downlink transmission signal allocation area) and an uplink subframe UL (uplink transmission signal allocation area) arranged side by side in the time direction. It is a communication system that performs duplexing of transmission and reception by a division duplex method. Note that the length of one radio frame is 5 msec.
The downlink subframe DL includes a preamble signal (Preamble) that is a known signal at the head. The preamble signal is a signal that is used for synchronization between the base station apparatus and the terminal apparatus, and that the terminal apparatus measures the signal strength from the base station apparatus. A plurality of patterns having different codes and the like are prepared for the preamble signal.

In the radio frame, since the preamble signal is arranged at the beginning of the downlink subframe DL, that is, at the beginning of the radio frame, the transmission signal transmitted by the radio base station apparatus 1 includes a period including a preamble signal that is a known signal. Are periodically arranged.
The preamble signal is a known signal defined in advance, and the time width of the preamble section including the preamble signal is also set to a predetermined constant value.

  Returning to FIG. 1, BBU 2 and RRU 3 are connected by a line using a transmission path such as optical fiber 4. An electric cable may be adopted as the transmission line instead of the optical fiber. Further, not only one RRU 3 but also a plurality of RRUs 3 may be connected to one BBU 2.

OBSAI is adopted as a connection interface between BBU2 and RRU3. However, other connection interfaces such as CPRI may be used.
In CPRI, BBU2 is called REC (Radio Equipment Control), and RRU3 is called RE (Radio Equipment Control).

The BBU 2 is a baseband signal that processes a baseband signal passed between the upper network I / F 21 for connecting to the upper network of the radio base station apparatus 1, the communication control unit 22 that controls communication, and the RRU 3. The unit 23 and the optical I / F 24 are provided.
The RRU 3 includes an optical I / F 31 and a wireless processing unit 32 that processes a high-frequency wireless signal transmitted and received from the antenna 33.
The optical I / F 24 and the optical I / F 31 are connection interface units compliant with OBSAI, and have a function of performing transmission control processing compliant with OBSAI. The optical I / F 24 and the optical I / F 31 together with the optical fiber 4 form a line connecting the BBU 2 and the RRU 3.

[2. RRU configuration]
FIG. 3 is a block diagram showing a configuration of the radio processing unit 32 of the RRU 3. The wireless processing unit 32 has one receiver 5 and one transmitter 6. The receiver 5 and the transmitter 6 are connected to the antenna 33 via the duplexer 7.

The receiver 5 includes a reception signal processing unit 5a, an ADC (AD converter) 5b, a filter 5c, a mixer 5d, and a reception amplifier 5e.
The reception signal received by the antenna 33 is given to the reception amplifier 5e via the duplexer 7. The reception amplifier 5e amplifies the reception signal and outputs it to the mixer 5d. An oscillator (not shown) is connected to the mixer 5d, and the mixer 5d converts the frequency of the received signal into a baseband frequency using a signal oscillated by the oscillator.
The received signal converted to the baseband frequency is given to the ADC 5b through the filter 5c formed of a bandpass filter or the like. The ADC 5b converts the received signal, which is an analog signal, into a digital signal and outputs the digital signal to the received signal processing unit 5a. The reception signal processing unit 5a performs quadrature demodulation on the digitally converted reception signal, and transmits the demodulated reception signal (IQ signal) to the BBU 2 via the optical I / F 31.

  The transmitter 6 includes a transmission signal processing unit 6a, a DAC (DA converter) 6b, a filter 6c, a mixer 6d, and a transmission amplifier 6e. Further, the transmitter 6 is configured to feed back the output signal of the transmission amplifier 6e to the transmission signal processing unit 6a, in addition to the coupler 6f connected to the subsequent stage of the transmission amplifier 6e, the mixer 6g, the filter 6h, and the ADC. (AD converter) 6i is provided.

  The transmission signal processing unit 6a is connected to the optical I / F 31, processes a data signal (transmission signal) to be wirelessly transmitted, which is transmitted from the BBU 2 as a digital signal (IQ signal), and outputs the data signal to the DAC 6b. . Further, the transmission signal processing unit 6a has a function of compensating for distortion of the transmission amplifier 6e and a function of determining whether there is a lack of data signals (details will be described later).

The DAC 6b converts a transmission signal, which is a digital signal, into an analog signal, and outputs the analog signal to the mixer 6d via a filter 6c including a band pass filter or the like. An oscillator (not shown) is connected to the mixer 6d. The mixer 6d converts a transmission signal into a high-frequency signal using a signal oscillated by the oscillator, and outputs the signal to the transmission amplifier 6e.
The transmission amplifier 6e receives the transmission signal converted into the high-frequency signal as an input signal and outputs the amplified transmission signal as an output signal. An antenna 33 is connected to the output terminal of the transmission amplifier 6e via the duplexer 7, and an output signal (transmission signal) output from the transmission amplifier 6e is transmitted from the antenna 33.
In the following description, a transmission signal input to the transmission amplifier 6e is also referred to as an input signal, and an amplified transmission signal output from the output terminal of the transmission amplifier 6e and acquired as a feedback signal is also referred to as an output signal.

  The coupler 6f connected to the latter stage of the output terminal of the transmission amplifier 6e acquires the output signal (amplified transmission signal) output from the transmission amplifier 6e and supplies it to the mixer 6g. The mixer 6g, the filter 6h, and the ADC 6i have substantially the same functions as the mixer 5d, the filter 5c, and the ADC 5b of the receiver 5, respectively, and the output signal obtained by the coupler 6f is converted into a digital signal. Then, it is given to the transmission signal processing unit 6a as a feedback signal.

  The wireless processing unit 32 includes a control unit 8 that comprehensively controls the operation of the RRU 3 and the like. The control unit 8 receives from the transmission signal processing unit 6a the notification of the determination result regarding the determination of the presence / absence of the signal and the detection notification indicating that the occurrence of the synchronization shift with the BBU 2 is detected. For example, control related to processing performed by the RRU 3 such as transmission stop of the transmission signal and restart of the RRU 3 is performed.

[3. First embodiment of transmission signal processing unit]
FIG. 4 is a block diagram showing a configuration of the transmission signal processing unit 6a according to the first embodiment.
The transmission signal processing unit 6a includes a modulation processing unit 40 that performs processing such as orthogonal modulation of the transmission signal provided from the BBU 2 via the optical I / F 31, and input / output characteristics of the transmission amplifier 6e with respect to the modulated transmission signal. And a distortion compensation unit 41 that performs distortion compensation generated in the above.
The distortion compensation unit 41 is a model that represents input / output characteristics using an input signal (amplified transmission signal) input to the transmission amplifier 6e and an output signal (amplified transmission signal) output from the transmission amplifier 6e. And distortion compensation is performed on the modulated transmission signal based on this estimation model. The distortion compensation unit 41 outputs the transmission signal after the distortion compensation to the DAC 6b.

  The transmission signal processing unit 6a includes an input signal buffer unit 42 that acquires and stores the input signal in order to acquire the input signal and the output signal used by the distortion compensation unit 40 to perform distortion compensation, and the output signal. And an output signal buffer unit 43 that acquires and accumulates.

The input signal buffer unit 42 is connected between the distortion compensation unit 41 and the DAC 6b, and acquires and accumulates input signals input to the transmission amplifier 6e via the DAC 6b and the like.
The output signal buffer unit 43 is connected to the ADC 6i that converts the output signal output from the transmission amplifier 6e fed back via the coupler 6f into a digital signal, and acquires and accumulates the output signal. Signal acquisition units 44 and 45 are individually connected to the input signal buffer unit 42 and the output signal buffer unit 43.

Both signal acquisition units 44 and 45 acquire signals included in the preamble section (see FIG. 2) from the input signals and output signals accumulated in the input signal buffer unit 42 and the output signal buffer unit 43 as acquisition signals.
Both signal acquisition units 44 and 45 acquire a signal (acquisition signal) based on the frame timing signal given from the frame timing acquisition unit 46.

The frame timing signal is a signal indicating the frame timing of the radio frame of the transmission signal, and is generated by the BBU2.
The frame timing acquisition unit 46 acquires a frame timing signal from the BBU 2 and gives it to both signal acquisition units 44 and 45.

FIG. 5 is a diagram for describing a mode in which both signal acquisition units 44 and 45 acquire a signal included in the preamble section as an acquisition signal based on the frame timing signal.
In FIG. 5, the horizontal axis indicates time, and the downlink transmission signal, the frame timing signal, and the signal acquisition timing transmitted by the radio base station apparatus 1 are respectively associated with the time axis in order from the top.

  As shown in the figure, the frame timing signal is a signal transmitted at either the H level or the L level lower than the H level, and from the H level to the L level at the start timing of each radio frame. Or from L level to H level. Accordingly, the frame timing signal indicates the start timing of each radio frame according to the timing at which the level is switched.

As described above, the preamble section is set to a predetermined time width predetermined from the beginning of the radio frame. Therefore, if the timing of the start of each radio frame can be recognized, the preamble section can be specified.
Therefore, both signal acquisition units 44 and 45 obtain the timing TE advanced by the preamble section, which is the period including the preamble signal, from the timing TS at the beginning of each radio frame based on the frame timing signal, Specify the preamble section.
Both signal acquisition units 44 and 45 acquire signals included between the timings TE from the timings TS among the input signals and output signals accumulated in the input signal buffer unit 42 and the output signal buffer unit 43, A signal included in the preamble section can be acquired as an acquisition signal.

In addition, both signal acquisition units 44 and 45 can acquire acquisition signals included in all preamble sections. However, when performing distortion compensation and determination of the absence or absence of signals, which will be described later, In some cases, it is less necessary to acquire a signal included in the preamble section.
Therefore, both signal acquisition units 44 and 45 of this embodiment acquire signals after a predetermined time.
Specifically, the time interval in which both signal acquisition unit 44 and 45 to acquire the acquisition signal, a relatively short distance D _S, it is set to two kinds of time intervals longer intervals D _L than.
The control unit 8 sets the time interval for acquiring the acquisition signals of both the signal acquisition units 44 and 45. Here, a case where two types of time intervals can be set is shown, but the time intervals may be set in more stages.

The frame timing of the input signal and the output signal accumulated in the input signal buffer unit 42 and the output signal buffer unit 43 is processed by each unit, so that a delay error is generated from the timing indicated by the frame timing signal. there is a possibility. Both signal acquisition parts 44 and 45 acquire an acquisition signal, correcting the delay error.
Returning to FIG. 4, both signal acquisition units 44 and 45 output the acquired acquisition signals to the correlation value calculation unit 47.

  The correlation value calculation unit 47 is similar between an acquisition signal from the signal acquisition unit 44 (hereinafter also referred to as a first acquisition signal) and an acquisition signal from the signal acquisition unit 45 (hereinafter also referred to as a second acquisition signal). A correlation value indicating the degree of sex is obtained.

The correlation value calculation unit 47 calculates the correlation value as a value in the range of “0” to “1”. The correlation value calculation unit 47 is closer to “1” as the degree of similarity between the first acquisition signal and the second acquisition signal is higher, and is set to “0” as the degree of similarity is lower. The correlation value is obtained so that the values are close.
That is, the correlation value indicates that the closer to “1”, the higher the correlation between both signals, and the closer to “0”, the lower the correlation between both signals.
The correlation value calculation unit 47 gives the obtained correlation value to the first determination unit 48 and the second determination unit 49.

  The first determination unit 48 determines whether or not to perform distortion compensation by the distortion compensation unit 41 based on the correlation value given from the correlation value calculation unit 47.

Here, in order to perform distortion compensation with high accuracy, it is necessary that the first acquisition signal and the second acquisition signal have high correlation, and each of the first acquisition signal and the second acquisition signal is a preamble signal. It must be acquired with high accuracy.
Therefore, the first determination unit 48 is configured to determine, for example, that the correlation value is “0.9” or more and that distortion compensation is performed.
If the correlation value is “0.9” or more, the first determination unit 48 gives the first and second acquired signals to the distortion compensation unit 41 and causes the distortion compensation unit 41 to perform distortion compensation.

The second determination unit 49 acquires the correlation value given from the correlation value calculation unit 47 as the detection result of the known signal in the transmission signal, and determines the presence / absence of a signal lack in the transmission signal based on this.
FIG. 6 is a diagram for explaining the relationship between the lack of signal that occurs in the transmission signal and the correlation value between the first acquisition signal and the second acquisition signal. FIG. 6A shows that the transmission signal is normal. When the input signal and the output signal are both normal by being transmitted to (b), when LOF is generated in the output signal due to LOF occurring in the transmission signal, (c) is LOF in the transmission signal. This shows how input and output signals are accumulated in both buffer units 42 and 43 when LOF occurs in both the input signal and the output signal.

  As shown in FIG. 6A, if the transmission signal is normally transmitted without causing the LOF, the preamble signal is included in the preamble sections of the input signal and the output signal. , 45 both include a preamble signal, and the degree of similarity between them is high. Therefore, the correlation value obtained by the correlation value calculation unit 47 is a high value.

  On the other hand, when LOF occurs in the transmission signal, for example, as shown in FIG. 6B, when LOF occurs only in the output signal, the second acquisition signal does not include the preamble signal but includes the noise component. Become. Therefore, the degree of similarity between the first acquisition signal that includes the preamble signal and the second acquisition signal that does not include the preamble signal is low, and the correlation value is low.

  For example, when LOF occurs in both the input signal and the output signal as shown in FIG. 6C, both the acquired signals do not include the preamble signal but include the noise component. Since the noise components are uncorrelated, the correlation value is a low value in this case as well.

As described above, the correlation value calculated by the correlation value calculation unit 47 from both acquired signals is a high value if the preamble signal is included in the transmission signal, and is a low value if it is not included. That is, the correlation value is obtained as a detection result of the preamble signal in the transmission signal.
FIG. 6 shows a case where LOF occurs, that is, a case where a signal lack occurs in units of radio frames. Based on the correlation value, it is determined whether or not a preamble signal is included in the acquired signal acquired from the preamble section. If detected, it is possible to determine the lack of signal in units of radio frames.

  Further, even if a signal lack occurs in which a part of a radio frame is missing instead of a radio frame unit, the transmission signal includes a preamble section including a preamble signal in each radio frame, so that a fixed period is obtained. Arranged at intervals. Therefore, if a preamble signal is included in the acquired signal acquired from the preamble section, there is no signal loss at least in this preamble section. It can be estimated that it is a transmission signal.

On the other hand, assuming that the acquired signal acquired from the preamble section is a noise component that cannot be determined to be a preamble signal, at least in this preamble section, a signal lack occurs, and the signals before and after that section are not normal, It can be presumed that there is a high probability that a lack of signal has occurred.
As described above, the second determination unit 49 of the present invention determines the presence or absence of a signal in the transmission signal based on the correlation value between the two acquisition signals acquired from the preamble sections arranged in the transmission signal at a constant frequency. can do.

Returning to FIG. 4, the second determination unit 49 notifies the control unit 8 of the determination result determined for the presence or absence of a signal.
The details of the process of determining the absence of a transmission signal performed by the second determination unit 49 will be described later.

In addition, the transmission signal processing unit 6a according to the present embodiment uses the CDR (Clock Data Recovery) unit 50 that reproduces an operation clock synchronized with BBU2 from the transmission signal from the BBU2, and the reproduction clock that is reproduced by the CDR unit 50. And a PLL 51 that generates a supply clock to be supplied to each device of the apparatus.
The CDR unit 50 detects the timing synchronized with the BBU2 obtained from the transmission signal, and adjusts the reproduction clock so that the phase of this timing is synchronized with the phase of the supply clock generated by the PLL 51, whereby the operation of the BBU2 A clock synchronized with the clock can be supplied.

  The CDR unit 50 cannot obtain the synchronization timing based on the reference transmission signal when the transmission signal is completely lost or the signal absence state continues for a certain period, and cannot maintain the synchronization state. And an out-of-synchronization (out of lock) with the supply clock.

The CDR unit 50 detects the occurrence of a synchronization error (out of lock) between the synchronization timing and the supply clock as described above, so that the transmission signal is not transmitted at all or the state in which the transmission signal is absent continues for a certain period of time. Can be detected.
When detecting the unlocking, the CDR unit 50 outputs an unlock detection notification indicating that the unlocking has been detected to the control unit 8 and the second determination unit 49.
Next, the process of determining the lack of signal of the transmission signal performed by the second determination unit 49 will be described.

[4. (Lack of signal judgment processing)
FIG. 7 is a flowchart illustrating a signal lack determination process of the transmission signal performed by the second determination unit 49.
First, when the second determination unit 49 acquires the correlation value from the correlation value calculation unit 47 (step S1), the second determination unit 49 determines whether or not the unlock detection notification is received from the CDR unit 50 (step S2).
If it is determined that the unlock detection notification is received from the CDR unit 50, the second determination unit 49 proceeds to step S12, notifies the control unit 8 of the first lack determination (step S12), and returns to the start. .

  The first lack determination is a determination indicating that there is a signal shortage that is severe enough to restart the RRU3 or stop transmission. In the CDR unit 50, when the unlocking is detected, it indicates that the transmission signal is not transmitted at all or the absence of the signal continues for a certain period as described above. It is determined that there is a lack of signal, and the first lack determination is notified. The control unit 8 that has received the first lack determination performs processing of restarting the RRU 3 or stopping transmission.

If it is determined in step S2 that the unlock detection notification has not been received, the second determination unit 49 determines whether or not the correlation value is smaller than “0.5” (step S3).
If it is determined that the correlation value is not smaller than “0.5”, that is, the correlation value is “0.5” or more, the second determination unit 49 further determines whether or not the correlation value is smaller than “0.9”. Is determined (step S4).

If it is determined that the correlation value is smaller than “0.9”, the second determination unit 49 notifies the control unit 8 of the first normal determination (step S5) and returns to the start.
The first normal determination is a determination indicating that there is no signal loss to the extent of a problem in performing wireless communication. The control unit 8 that has received the first normal determination performs processing for leaving a log regarding the determination.

If it is determined in step S4 that the correlation value is not smaller than “0.9”, that is, the correlation value is “0.9” or more, the second determination unit 49 makes the second normal determination to the control unit 8. Notify (step S6) and return.
The second normal determination is a determination indicating that there is no signal loss. This is because when the correlation value is “0.9” or more, it can be determined that there is no lack of preamble signal in the preamble section. The control unit 8 that has received the second normal determination recognizes that there is no lack of signal.

As described above, when the correlation value is “0.5” or more (step S3), the second determination unit 49 notifies the control unit 8 of the first and second normal determinations (step S5). S6), it is determined that there is no signal loss in the transmission signal.
That is, in the present embodiment, in determining the correlation value, “0.5” is set as a threshold value, and if it is smaller than “0.5”, there is no signal in one of the first and second acquired signals. And it is configured to determine that a lack of signal has occurred in the transmission signal.

In step S3, the correlation value may be a value close to “0.5” and it may be determined that there is no signal loss. Therefore, the correlation value is “0.5” (third threshold) or more and “ When the second determination unit 49 determines that the value is smaller than “0.9” as the fourth threshold value, which is a value larger than 0.5, the control unit 8 performs processing for leaving a log regarding this determination.
Thereby, even when it is determined that there is no lack of signal in the transmission signal, preventive processing can be performed by leaving a log of the determination.

On the other hand, when it is determined in step S3 that the correlation value is smaller than “0.5”, the second determination unit 49 has a time interval for acquiring the first and second acquisition signals by the signal acquisition units 44 and 45, It is determined whether or not the interval _DL is set (step S7).

If the time interval for obtaining the first and second acquisition signal is set to the distance D _L, the second determination unit 49, the setting of the time interval for obtaining the first and second acquisition signals, the distance D _L transmitting a notification for changing the spacing D _S is shorter interval than the control unit 8 (step S8).
Controller 8 having received the notification, the time interval of obtaining the first and second acquisition signal controls the signal acquisition unit 44 and 45 so that the distance D _S. Thus, the time interval of obtaining the first and second acquisition signal is changed to the interval D _S is shorter intervals.

In step S7, if the time interval of obtaining the first and second acquisition signal is already assigned to a distance D _S, the second determination unit 49 proceeds to step S9.

As described above, in the present embodiment, when the second determination unit 49 has a correlation value smaller than “0.5” as the predetermined first threshold, the time for acquiring the acquisition signals by the signal acquisition units 44 and 45. control is performed to the distance D _S is a small value intervals. That is, since the correlation value is smaller than “0.5”, if the second determination unit 49 determines that the preamble signal is not included in the first or second acquisition signal and the transmission signal is missing, Since the time interval at which the control unit 8 acquires the first and second acquisition signals is reduced, it is possible to reliably determine the presence or absence of the signal even if the transmission signal is intermittently missing.

  Next, the second determination unit 49 obtains, as the frequency F, the number of times that the correlation value has been determined to be smaller than “0.5” during the past certain period, that is, the number of times that the signal lack has occurred in the transmission signal ( Step S9).

The second determination unit 49 determines whether or not the obtained frequency F is _{equal to} or greater than a predetermined threshold F _Th1 (step S10).
When it is determined that the frequency F is not _{equal to} or higher than the threshold value F _Th1 , that is, smaller than the threshold value F _Th1 , the second determination unit 49 proceeds to step S5 and notifies the control unit 8 of the first normal determination (step S5 ) Go back to the start. Here, the threshold value F _Th1 is set to a value that is relatively low as the frequency of occurrence of signal loss, and is not recognized as intermittent or continuous signal loss.

If the frequency F is extremely small, it is not recognized that the lack of signal in the transmission signal is intermittently generated. Therefore, the second determination unit 49 determines that the frequency F is higher than a threshold value _FTh1 as a predetermined threshold value. If it is smaller, it is determined that there is a sudden signal loss, and a first normal determination notification is made to determine that there is no signal loss in the transmission signal.
Note that even if it is not recognized that the lack of signal of the transmission signal occurs intermittently, there is a possibility that the lack of signal may occur. Therefore, since the frequency F is smaller than the threshold value _FTh1 , there is no lack of signal. When the second determination unit 49 makes a determination to be considered, the second determination unit 49 notifies the first normal determination to cause the control unit 8 to perform a process of leaving a log regarding this determination.
Even if the frequency of the signal lack is small, it is determined that the signal lack has occurred. Therefore, it is possible to perform a preventive process by leaving a log regarding this determination.

In step S10, if it is determined that the frequency F is the threshold value _{F Th1} or more, the second determination unit 49 determines whether the frequency F is the threshold value _{F Th2} or set to a value greater than the threshold value _{F Th1} (step S11). Here, the threshold value F _Th2 is set to a value that is large as the frequency of occurrence of signal loss and is recognized as intermittent or continuous signal loss.

If it determines with frequency F being more than threshold value _FTh2 , the 2nd determination part 49 will notify the 1st lack determination with respect to the control part 8 (step S12), and will return.
As described above, the first lack determination is a determination indicating that a severe signal loss has occurred. Therefore, when the frequency F is equal to or higher than the threshold F _Th2 that is another predetermined threshold, the second determination unit 49 determines that the transmission signal has a severe signal lack by notifying the first lack determination. Further, in this case, when the second determination unit 49 determines that the transmission signal has a severe signal lack, the control unit 8 transmits the transmission signal in response to the notification of the first lack determination. Stop or restart the device itself.
For this reason, it is possible to quickly stop transmission of the transmission signal as an appropriate process according to the determination of the second determination unit 49 or restart the own apparatus by the determination on the RRU 3 side.

Further, in step S11, the frequency F is not the threshold value _{F Th2} above, i.e., and the frequency F is the threshold value _{F Th1} or, if less than the threshold value _{F Th2,} the second determination unit 49, the second to the control unit 8 Is notified (step S13), and the process returns.
The second lack determination is a determination indicating that there is a slight signal lack that does not lead to a severe signal lack like the first lack determination. The control unit 8 that has received the second lack determination performs a process of transmitting a warning such as an alarm for notifying that a signal lack has occurred to the BBU 2 and also performs a process of leaving a log regarding this determination.

As described above, when the frequency F is equal to or higher than the threshold value F _Th1 and smaller than the threshold value F _Th2 , the second determination unit 49 notifies the second absence determination, thereby causing a slight signal lack in the transmission signal. Furthermore, if the second determination unit 49 determines that the transmission signal has a slight signal loss, the control unit 8 notifies the BBU 2 of a warning and records a log of the determination. In addition, it is possible to promptly notify the BBU 2 and record a log as appropriate processing according to the determination of the second determination unit 49 by the determination on the RRU 3 side.

As described above, when the correlation value is smaller than the value “0.5” as the second threshold, the second determination unit 49 determines the number of times that it is determined that the correlation value is smaller than “0.5” during the past certain period. The frequency F is obtained, and according to the frequency F, it can be determined whether the degree of signal lack in the transmission signal corresponds to mild or severe.
That is, the second determination unit 49 converts the number of times that the correlation value is determined to be smaller than the predetermined second threshold value “0.5” into a frequency, and based on this frequency, the signal lack in the transmission signal The presence or absence of is determined as the degree.
In the present embodiment, when the correlation value is smaller than the value “0.5” as the second threshold value, it is determined that a signal lack has occurred in the transmission signal. It is possible to determine the frequency at which it is determined that the occurrence of the signal occurs, and based on this frequency, it is possible to determine the lack of signal in the transmission signal as the degree. Further, by determining the lack of signal as a degree, it is possible to more suitably perform processing for the lack of signal.

  Further, as described above, the second determination unit 49 according to the present embodiment determines whether the signal lack is a slight signal lack or a severe signal lack, and determines that the signal is lacking. In this case, when the control unit 8 notifies the BBU 2 of a warning and records a log of this determination, and determines that the signal is severely absent, it stops transmission of the transmission signal and restarts its own device. Therefore, it is possible to quickly perform a suitable process according to the degree of lack of the transmission signal based on the determination on the wireless communication apparatus side.

  In FIG. 7, the threshold values “0.5” and “0.9” relating to the correlation values shown in step S3 and step S4 are exemplarily shown, and are not limited to these values.

[5. (Effect)
As described above, the RRU 3 of the radio base station apparatus 1 according to the present embodiment is a radio communication apparatus in which a transmission signal in which a preamble section including a preamble signal is periodically arranged is given from the BBU 2, A second determination unit 49 is provided for determining the presence or absence of a signal in the transmission signal based on the correlation value obtained from the first and second acquisition signals indicating the detection result of the preamble signal.

  More specifically, the RRU 3 performs correlation based on the signal acquisition units 44 and 45 that acquire signals included in the preamble section of the transmission signal, and the first and second acquisition signals acquired by the signal acquisition units 44 and 45. A correlation value calculation unit 47 that obtains a value as a detection result of the preamble signal in the transmission signal, and the second determination unit 49 determines a signal in the transmission signal based on the correlation value obtained by the correlation value calculation unit 47. It is configured to determine whether there is a lack.

According to the RRU 3 having the above configuration, the second determination unit 49 determines the presence or absence of a signal in the transmission signal based on the detection result of the preamble signal periodically arranged in the transmission signal. The presence or absence of a signal can be determined for each period.
As a result, even if the signal lack occurs intermittently in the transmission signal, it is possible to appropriately detect the signal lack in the transmission signal by periodically determining the presence or absence of the signal lack.

  Here, the correlation value calculation unit 47 obtains a correlation value between the first acquisition signal and the second acquisition signal acquired by the signal acquisition units 44 and 45. In this case, the first acquisition signal and the second acquisition signal constitute a reference signal for determining whether one signal contains a known signal in the other signal.

Further, the RRU 3 of the present embodiment has a function for compensating for distortion occurring in the input / output characteristics of the transmission amplifier 6e as an amplifier.
That is, the RRU 3 of the present embodiment has a transmission amplifier 6e that outputs a transmission signal as an input signal and an amplified transmission signal as an output signal, and input / output of the transmission amplifier 6e as a function for performing distortion compensation. And a distortion compensation unit 41 that compensates for distortion occurring in characteristics.

  The signal acquisition units 44 and 45 acquire a signal included in a preamble section in the input signal and the output signal as a first acquisition signal and a second acquisition signal, and give the acquired signal to the correlation value calculation unit 47. Furthermore, the correlation value calculation unit 47 and the first determination unit 48, the distortion compensation unit 41 is provided.

  According to this configuration, the signal acquisition units 44 and 45 acquire the input signal and output signal of the transmission amplifier 6e necessary for the distortion compensation unit 41 to perform distortion compensation of the transmission amplifier 6e, and the correlation value calculation unit 47 Since the correlation value is obtained by using these input / output signals, the second determination unit 49 and the distortion compensation unit 41 can serve as the signal acquisition units 44 and 45, and the apparatus scale can be made compact.

[6. Second embodiment of transmission signal processing unit]
FIG. 8 is a block diagram showing a configuration of the transmission signal processing unit 6a according to the second embodiment.
The difference between the present embodiment and the first embodiment is that the second correlation that gives the correlation value to the second determination unit 49 in addition to the (first) correlation value calculation unit 47 that gives the correlation value to the first determination unit 48 A delay calculation unit 52 that is connected between the ADC 6 i (FIG. 3) and the (first) output signal buffer unit 43 and that receives the output signal, and a delay output from the delay processing unit 52. The second output signal buffer unit 53 that acquires and stores the processed output signal, and the signal included in the preamble section (FIG. 2) is acquired as an acquisition signal from the output signal stored in the second output signal buffer unit 53. It is the point which is equipped with the signal acquisition part 54 which performs.

The delay processing unit 52 performs a delay process for delaying the output signal by a predetermined delay time. Therefore, the output signal accumulated in the second output signal buffer unit 53 is delayed by a predetermined delay time with respect to the output signal of the first output signal buffer unit 43.
The signal acquisition unit 54 acquires a signal included in the preamble section of the output signal delayed by a predetermined delay time as an acquisition signal, and calculates the acquired signal (hereinafter also referred to as a third acquisition signal) as a second correlation value. This is output to the unit 55. Therefore, the third acquisition signal is delayed by a predetermined delay time with respect to the second acquisition signal, and the signal acquired from the preamble section at a different timing from the preamble section from which the second acquisition signal was acquired; Become.

The second correlation value calculation unit 55 obtains a correlation value between the second acquisition signal from the signal acquisition unit 45 and the third acquisition signal from the signal acquisition unit 54.
Here, the second correlation value calculation unit 55 obtains a correlation value using the second and third acquired signals that are two acquired signals acquired from preamble sections having different timings. In this case, a high correlation value is obtained if both the second acquisition signal and the third acquisition signal include a preamble signal, and low if either or both (due to lack) do not include a preamble signal. A correlation value is obtained. Thus, the second correlation value calculation unit 55 can obtain the correlation value as a detection result of the presence / absence of the preamble signal in the transmission signal.

In the first embodiment, since the output signal corresponding to the input signal input to the transmission amplifier 6e is obtained by feedback, the input signal and the output signal are synchronized so that they are radio frames having the same timing. There is a case. Therefore, the first and second acquisition signals may be signals acquired from preamble sections at the same timing.
On the other hand, in this embodiment, since the correlation value can be obtained from the signals acquired from the two preamble sections at different timings by the delay processing unit 52, the preamble signal included in the transmission signal is more efficiently used. Can be detected well.

  Also in the present embodiment, since the second determination unit 49 also serves as a part of functional units necessary for performing distortion compensation of the transmission amplifier 6e, the apparatus scale can be reduced.

[7. Third embodiment of transmission signal processing unit]
FIG. 9 is a block diagram showing a configuration of the transmission signal processing unit 6a according to the third embodiment.
The difference between the present embodiment and the second embodiment is that a second input signal buffer unit 60, a delay processing unit 62, and a third unit are used as functional units for acquiring an acquisition signal given to the second correlation value calculation unit 55. An input signal buffer unit 63 and signal acquisition units 61 and 64 are provided.

In the present embodiment, the second input signal buffer unit 60 and the delay processing unit 62 are connected to the subsequent stage of the distortion compensation unit 41, and both acquire an input signal.
The second input signal buffer unit 60 acquires and accumulates input signals. The signal acquisition unit 61 connected to the second input signal buffer unit 60 acquires a signal included in the preamble section (hereinafter also referred to as a fourth acquisition signal) from the input signal accumulated in the second input signal buffer unit 60. And output to the second correlation value calculation unit 55.

The delay processing unit 62 performs a delay process for delaying the input signal by a predetermined delay time. Therefore, the input signal accumulated in the third input signal buffer unit 63 is delayed by a predetermined delay time with respect to the input signal of the second input signal buffer unit 60.
The signal acquisition unit 64 connected to the third input signal buffer unit 63 acquires a signal included in the preamble section of the input signal delayed by a predetermined delay time, and acquires the acquired signal (hereinafter also referred to as a fifth acquisition signal). Is output to the second correlation value calculation unit 55. Therefore, the fifth acquisition signal is delayed by a predetermined delay time with respect to the fourth acquisition signal, and a signal acquired from a preamble section at a different timing from the preamble section from which the fourth acquisition signal was acquired; Become.

The second correlation value calculation unit 55 obtains a correlation value between the fourth acquisition signal from the signal acquisition unit 61 and the fifth acquisition signal from the signal acquisition unit 64.
Here, the second correlation value calculation unit 55 calculates a correlation value using the fourth and fifth acquisition signals acquired from the preamble sections at different timings. Thereby, the second correlation value calculation unit 55 can obtain the correlation value as a detection result of the presence / absence of the preamble signal in the transmission signal.

  In the present embodiment, the function unit for acquiring an acquisition signal for obtaining a correlation value necessary for performing the determination is provided separately from the function unit for performing distortion compensation. An acquisition signal can be acquired at a timing suitable for determination.

[8. Fourth embodiment of transmission signal processing unit]
FIG. 10 is a block diagram showing a configuration of the transmission signal processing unit 6a according to the fourth embodiment.
The difference between the present embodiment and the third embodiment is whether the fourth acquisition signal includes a preamble signal instead of the delay processing unit 62, the third input signal buffer unit 63, and the signal acquisition unit 64. This is the point that a storage unit 65 that stores in advance a preamble signal for determining whether or not.

  The second correlation value calculation unit 55 of the present embodiment obtains a correlation value between the fourth acquisition signal from the signal acquisition unit 61 and the preamble signal stored in the storage unit 65. Based on this correlation value, the second determination unit 49 determines whether there is a signal lack in the transmission signal.

The storage unit 65 stores preamble signals of all patterns as data. The second correlation value calculation unit 55 can specify the current preamble signal pattern based on the notification from the BBU 2, reads the preamble signal of the specified pattern from the storage unit 65, and uses it for calculating the correlation value.
In the present embodiment, if the fourth acquisition signal is acquired, a correlation value with the preamble signal stored in advance in the storage unit 65 can be obtained, and the presence or absence of a signal in the transmission signal can be determined. As a result, the process related to determination is simplified.

  In the present embodiment, even if there is no notification for specifying the preamble signal pattern from the BBU 2, the second correlation value calculation unit 55 obtains correlation values between the preamble signals of all patterns and the current preamble signal. The current preamble signal can also be specified.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Radio base station equipment (wireless communication system)
2 Baseband unit (baseband processing device)
3 Remote radio unit (wireless communication device)
6e Transmitting amplifier (amplifier)
8 Control Unit 41 Distortion Compensation Unit 44, 45, 54, 61, 64 Signal Acquisition Unit 47 (First) Correlation Value Calculation Unit 48 First Determination Unit (Other Determination Unit)
49 Second determination unit (determination unit)
55 Second correlation value calculation unit 65 Storage unit

Claims (10)

A wireless communication device in which a transmission signal in which sections including a known signal are periodically arranged is given from a baseband processing device,
A wireless communication apparatus, comprising: a determination unit that determines presence or absence of a signal in the transmission signal based on a detection result of a known signal in the transmission signal. A signal acquisition unit for acquiring a signal included in the section of the transmission signal;
A correlation value calculation unit for obtaining a correlation value based on the acquired signal acquired by the signal acquisition unit as a detection result of a known signal in the transmission signal, and
The wireless communication apparatus according to claim 1, wherein the determination unit determines whether or not there is a signal lack in the transmission signal based on the correlation value obtained by the correlation value calculation unit. An amplifier that receives the transmission signal as an input signal and outputs the amplified transmission signal as an output signal;
A distortion compensation unit that compensates for distortion occurring in the input / output characteristics of the amplifier, and
3. The signal acquisition unit according to claim 2, wherein the signal acquisition unit acquires a signal included in the section of the input signal and a signal included in the section of the output signal and supplies the signal to the correlation value calculation unit and the distortion compensation unit. Wireless communication device.   The wireless communication apparatus according to claim 2 or 3, wherein the correlation value calculation unit obtains a correlation value using two acquired signals acquired from different sections. A storage unit for storing the known signal;
The wireless communication apparatus according to claim 2, wherein the correlation value calculation unit obtains a correlation value between the acquired signal acquired by the signal acquisition unit and the known signal stored in advance in the storage unit. The signal acquisition unit acquires a signal included in the section in the transmission signal at a predetermined time interval,
6. The apparatus according to claim 2, further comprising: a control unit configured to reduce a time interval for acquiring the acquired signal by the signal acquisition unit when the correlation value is smaller than a predetermined first threshold value. A wireless communication device according to 1.   The said determination part determines the presence or absence of the signal lack in the said transmission signal as a degree based on the frequency | count that it determined with the said correlation value being smaller than the predetermined 2nd threshold value. A wireless communication device according to 1. The determination unit determines whether the signal lack is a slight signal lack or a severe signal lack,
A means for notifying the baseband processing device of a warning and / or recording a log of the determination when determining that the signal is mildly absent;
The wireless communication apparatus according to claim 7, further comprising means for stopping transmission of the transmission signal and / or restarting the own apparatus when it is determined that the signal is severely absent.   When the correlation value is not less than a third threshold that can be determined that there is no signal loss in the preset transmission signal and is smaller than a fourth threshold that is set to a value larger than the third threshold. The wireless communication apparatus according to any one of claims 2 to 8, further comprising means for leaving a log of the determination when the determination unit determines. A baseband processing device;
A wireless communication device provided with a transmission signal in which sections including known signals are periodically arranged are provided from the baseband processing device,
The wireless communication device
A wireless communication system, comprising: a determination unit that determines presence or absence of a signal in the transmission signal based on a detection result of a known signal in the transmission signal.

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