JP2011030057A - Wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To guarantee signal quality of an entire system even if a fault of a specific RF section occurs within one frame term, in a wireless communication system. <P>SOLUTION: A receiving-side communication apparatus includes receivers of two or more systems and a full-system reception processing section 51 which receives input of reception signals of the respective systems and estimation results of channel characteristics from the receivers. Each of the receivers includes: reception signal processing means (antennas 31, 41, RF sections 32, 42, baseband sections 34, 44) for processing reception signals of the respective systems; fault detecting means 33, 43 for detecting predetermined fault situations; and output signal control means (baseband sections) for outputting a predetermined signal to the full-system reception processing section prior to or in place of the estimation result of the channel characteristics for the reception signal in the case where the predetermined fault situation is detected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio communication system, and more particularly to a radio communication system that guarantees signal quality of the entire system even when a failure of a specific RF unit occurs within one frame period, for example.

In general, in wireless communication, transmission is performed based on a unit of a frame of a certain period.
Also, at the head of each frame, a determination is made as to whether the frame is a signal that has been correctly received (to be received) or a reserved signal.
Here, since the determination is performed in units of one frame as described above, if a failure occurs within one frame period, it is recognized that the signal is correct at the head of the frame, so The signal at the time of failure is processed as a correct signal until it reaches.

JP 2008-131651 A

  However, for example, in a radio communication system that includes a plurality of receiving units and receives them by combining or weighting them, when a failure occurs in a radio frequency (RF) unit in the receiving unit, it is not desirable from the RF unit. When the signal is output to the baseband unit and the signals of the receiving units are combined or weighted, there is a problem that the quality of the combined signal is deteriorated. As a specific example, when a signal to be handled is a video signal, there is a concern that the video may be interrupted or block noise may occur due to deterioration.

  The present invention has been made in view of such a conventional situation. For example, even when a failure of a specific RF unit occurs within one frame period, it is possible to guarantee the signal quality of the entire system. An object of the present invention is to provide a wireless communication system.

In order to achieve the above object, in the present invention, a wireless communication system having a receiving-side communication device including two or more receiving units has the following configuration.
That is, the communication device on the receiving side inputs the received signal of each system and the estimation result of the channel characteristic from each of the two or more receiving units and the two or more receiving units, and estimates the channel characteristic. And an all-system reception processing unit for processing the received signal based on the above.
Each of the two or more receiving units estimates the channel characteristics based on the received signal processing means that processes the received signals of each system and outputs them to the all-system received processing unit, and the received signals of each of the systems. and channel characteristics estimation means for outputting the estimation result to the entire system reception processing unit and a failure detecting means for detecting a predetermined failure situation, when the predetermined failure condition is detected by said failure detecting means The predetermined failure condition is detected before the channel characteristic estimation result by the channel characteristic estimation unit or instead of the channel characteristic estimation result by the channel characteristic estimation unit with respect to the received signal when the failure condition is detected Output signal control means for outputting a signal corresponding to the received signal to the all-system reception processing unit.

  Therefore, when a predetermined failure situation is detected in the communication apparatus on the receiving side, the received signal when the failure situation is detected is replaced with the channel characteristic estimation result before the channel characteristic estimation result. Thus, since a signal corresponding to when the predetermined failure condition is detected is output to the all-system reception processing unit, for example, even when a specific RF unit failure occurs within one frame period, The signal quality of the entire system can be guaranteed.

Here, various things may be used as a predetermined failure situation.
Further, the output signal control means, for example, outputs a signal corresponding to the detection of a predetermined failure situation before the channel characteristic estimation result of the channel characteristic estimation means for the received signal when the failure situation is detected. It may be mode in which the output is used to the full system receive processing unit, or the received signal when a fault condition is detected, instead of the estimation result of the channel characteristic due to channel characteristics estimation means, predetermined failure situations detected A mode of outputting a signal corresponding to the received signal to the all-system reception processing unit may be used.

The radio communication system according to the present invention has the following configuration as an example configuration.
That is, the present invention is applied to a MIMO wireless communication system that wirelessly transmits a signal from a transmission-side communication device including two or more transmission units to a reception-side communication device including two or more reception units.
In the communication device on the receiving side, each of the two or more systems of receiving units serves as a processing unit that constitutes the received signal processing means, an antenna that receives a radio signal, and an RF that processes a signal received by the antenna. And a baseband unit for processing signals processed by the RF unit.
The failure detection means detects the failure status of the RF unit as the predetermined failure status and outputs the detection result to the baseband unit.
The baseband unit includes the channel characteristic estimation unit, the output signal control unit, and a signal storage unit that stores a signal corresponding to the predetermined failure situation (for example, in a memory). .
The output signal control unit, when the detection result of the failure status of the RF section from said failure detecting means is input, channel by the channel characteristic estimating unit for a frame of the received signal when said fault condition is detected The signal stored in the signal storage unit is output to the all-system reception processing unit before the characteristic estimation result or instead of the channel characteristic estimation result by the channel characteristic estimation unit.

  Therefore, when a failure situation of the RF unit is detected in the communication device on the receiving side, the channel of the received signal when the failure situation is detected is estimated before the channel characteristic estimation result or the channel characteristic estimation. Instead of the result, since a signal corresponding to when a failure situation is detected is output to the entire system reception processing unit, for example, even when a failure of a specific RF unit occurs within one frame period, The signal quality of the entire system can be guaranteed.

Here, various numbers may be used as the number of transmission units of two or more systems included in the communication device on the transmission side and the number of reception units of two or more systems included in the communication device on the reception side.
In addition, as the communication device on the transmission side and the communication device on the reception side, for example, a communication device having both functions on the transmission side and functions on the reception side may be used.

  As described above, the radio communication system according to the present invention can guarantee the signal quality of the entire system even when, for example, a failure of a specific RF unit occurs within one frame period.

It is a figure which shows the structural example of a 2x2 MIMO radio | wireless communications system which has 2 transmission parts and 2 reception parts which concern on one Example of this invention. It is a figure which shows the structural example of the receiving baseband part of the 1st system | strain which concerns on one Example of this invention. It is a figure which shows the truth table which concerns on one Example of this invention. It is a figure which shows an example of the timing chart at the time of the failure generation which concerns on one Example of this invention. It is a figure which shows an example of the timing chart at the time of the failure generation which concerns on a prior art.

Embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration example of a second × 2 MIMO (Multiple Input Multiple Output) wireless communication system having a receiving portion of the transmitting portion and the two systems of two systems according to an embodiment of the present invention.
The wireless communication system of this example includes a communication device on the transmission side and a communication device on the reception side. Here, in this example, the transmission function of the communication device on the transmission side and the reception function of the communication device on the reception side will be described. However, a communication device having both the transmission function and the reception function may be used.
Further, in the wireless communication system of the present example, an Orthogonal Frequency Division Multiplexing (OFDM) scheme is used.

The transmission-side communication apparatus includes a MIMO transmission processing unit 1 common to the two systems, and the first system transmission baseband unit 11 and the first system transmission RF are used as the first system (TX1). and parts 12, provided with a transmitting antenna 13 of the first line, also, as a second line (TX2), a transmission baseband unit 21 of the second system, the transmission RF unit 22 of the second system, the second A transmission antenna 23 of the system is provided.
As a first system (RX1), the reception-side communication device includes a first system reception antenna 31, a first system reception RF unit 32, a first system reception RF unit monitoring / failure detection unit 33, A first system reception baseband unit 34 is provided, and a second system reception antenna 41, a second system reception RF unit 42, and a second system reception RF are provided as a second system (RX2). And a second system reception baseband unit 44, and a MIMO reception processing unit 51 common to the two systems.
Here, hyx (y and x are 1 or 2 respectively) shown in FIG. 1 represents the transmission path characteristic from the x-th system transmission unit to the y-th system reception unit.

An example of the operation performed in the wireless communication system of this example will be shown.
A communication device on the transmission side will be described.
The MIMO transmission processing unit 1 performs encoding, pilot arrangement, and phase control according to the applied MIMO transmission method, and outputs the signal to the first system transmission baseband unit 11 and the second system transmission baseband unit 21.
In this example, Alamouti (STBC) code is used. Alamouti coding is performed by using two signals S (0) and S (1) for a modulated signal sequence {S (n)} = S (0), S (1),. Is one block, (S (0), -S (1) ^* ) is sent to the first system transmission baseband unit 11, and (S (1), S (0) ^* ) is sent to the second system transmission baseband unit 21. Are output respectively. The same applies to the subsequent S (2) and S (3). The pilot carrier and all subcarriers in the frame synchronization period are not necessarily limited to those described above. For example, a predetermined pilot signal sequence is alternately transmitted from the first system and the second system for each OFDM symbol (that is, one is a pilot signal). The other may not transmit signals on the same subcarrier).

The first line transmission baseband unit 11, to the signal input from the MIMO transmission processing unit 1, the conversion of the time axis signal from the frequency-axis signal by performing addition or the like of the guard interval, the first line transmission RF unit 12 is output.
The first system transmission RF unit 12 performs D / A (Digital to Analog) conversion, conversion to a transmission frequency band, and the like on the signal input from the first system transmission baseband unit 11, and the first system transmission baseband unit 11 Output to the transmitting antenna 13.
The first system transmission antenna 13 transmits the signal input from the first system transmission RF unit 12 to the first system reception antenna 31 and the second system reception antenna 41 by radio.

The second system transmit baseband unit 21, to the signal input from the MIMO transmission processing unit 1, the conversion of the time axis signal from the frequency-axis signal by performing addition or the like of the guard interval, the second system transmits RF unit 22 to output.
The second system transmission RF unit 22 performs D / A conversion, conversion to a transmission frequency band, and the like on the signal input from the second system transmission baseband unit 21, and outputs the result to the second system transmission antenna 23. To do.
The second system transmission antenna 23 transmits the signal input from the second system transmission RF unit 22 to the first system reception antenna 31 and the second system reception antenna 41 by radio.

The receiving side communication device will be described.
The first system reception antenna 31 receives signals transmitted from the first system transmission antenna 13 and the second system transmission antenna 23 and outputs the signals to the first system reception RF unit 32.
The first system reception RF unit 32 performs frequency conversion to the baseband, AGC (Automatic Gain Control), and A / D (Analog to Digital) conversion on the reception signal input from the first system reception antenna 31. The signal is output to the first system reception baseband unit 34.
Further, the first system reception RF unit 32 outputs information such as the received signal strength, the power source, and the state of each analog IC (Integrated Circuit) to the first system reception RF unit monitoring / failure detection unit 33.

The first line receiver RF unit monitoring and fault detection unit 33 based on information such as the input power and the analog IC from the first line receiver RF section 32, the normal RF unit (the first line receiver RF section 32) And a determination signal false ₁ representing the determination result is output to the first system reception baseband unit 34. For example, it is assumed that the determination signal false ₁ indicates normality when it is 0 and indicates abnormality when it is 1.

The first system reception baseband unit 34 takes in the signal digitally converted by the first system reception RF unit 32, performs frequency conversion and transmission path estimation, and outputs the result to the MIMO reception processing unit 51.
Further, the first system reception baseband unit 34 outputs an output signal to the MIMO reception processing unit 51 according to the failure information (determination signal false ₁ ) input from the first system reception RF unit monitoring / failure detection unit 33. Disconnect or perform specific output.

The second system reception antenna 41 receives signals transmitted from the first system transmission antenna 13 and the second system transmission antenna 23 and outputs the signals to the second system reception RF unit 42.
The second-system reception RF unit 42 performs frequency conversion, AGC, and A / D conversion to the baseband band on the reception signal input from the second-system reception antenna 41, and outputs the signal to the second-system reception base. The data is output to the band unit 44.
The second system reception RF unit 42 outputs information such as the received signal strength, the power source, and the state of each analog IC to the second system reception RF unit monitoring / failure detection unit 43.

The second system receiving RF unit monitoring and fault detection unit 43 based on information such as the input power and the analog IC from the second line receiver RF section 42, the normal RF unit (the second line receiver RF section 42) And a determination signal false ₂ representing the determination result is output to the second system reception baseband unit 44. For example, it is assumed that the determination signal false ₂ indicates normality when it is 0 and indicates abnormality when it is 1.

The second system reception baseband unit 44 takes in the signal digitally converted by the second system reception RF unit 42, performs frequency conversion and transmission path estimation, and outputs the result to the MIMO reception processing unit 51.
Further, the second system reception baseband unit 44 outputs an output signal to the MIMO reception processing unit 51 according to the failure information (determination signal false ₂ ) input from the second system reception RF unit monitoring / failure detection unit 43. Disconnect or perform specific output.
The MIMO reception processing unit 51 synthesizes or separates the signals of the two systems input from the first system reception baseband unit 34 and the second system reception baseband unit 44, and obtains signals transmitted from the respective systems, respectively. .

FIG. 2 shows a configuration example of the first system reception baseband unit 34.
The first system reception baseband unit 34 includes an FFT (Fast Fourier Transform) computing unit 101, a delay unit 102, a hy1 channel estimator 103, a hy2 channel estimator 104, a time axis synchronization signal detector 105, a frequency An axis synchronization signal detector 106, an abnormal time estimated value storage 107, and a (channel estimation result) output signal switch 108 are provided.

Here, in the first system reception baseband unit 34, y = 1 in FIG.
Also, the configuration and operation of the second system reception baseband unit 44 are the same as the configuration and operation of the first system reception baseband unit 34 shown in FIG. In the reception baseband unit 44, y = 2 in FIG.

An example of the operation performed in the first system reception baseband unit 34 shown in FIG.
FFT processor 101, (input from the first line receiver RF section 32) the received signal and converts the time domain signal st ₁ to a frequency axis signal sf _1, delayer 102 and h11 channel estimator 103 and h12 channel Output to the estimator 104 and the frequency axis synchronization signal detector 106.
The delay unit 102 delays the signal sf ₁ input from the FFT computing unit 101 and outputs the delayed signal sf _{1_delay} (to the MIMO reception processing unit 51).

The h11 channel estimator 103 extracts the pilot signal added by the first system transmission unit from the output signal sf ₁ from the FFT calculator 101, estimates the channel h11 based on the pilot signal, and obtains the estimation result. Output to the output signal switch 108.
The h12 channel estimator 104 extracts the pilot signal added by the second system transmission unit from the output signal sf ₁ from the FFT computing unit 101, estimates the channel h12 based on the pilot signal, and obtains the estimation result. Output to the output signal switch 108.
When the estimation result cannot be obtained from the current OFDM symbol, the h11 channel estimator 103 and the h12 channel estimator 104 output the result that can be estimated immediately before.

The time axis synchronization signal detector 105 detects the beginning of a predetermined frame from the received signal st ₁ (input from the first system reception RF unit 32) by a synchronization word or guard correlation calculation on the time axis, and performs time axis synchronization. and it outputs a detection signal Sync_t _y to the output signal switching device 108. The time axis synchronization detection signal Sync_t _y, for example, and outputs 0 when the synchronization signal (signal for synchronization) is undetected, and outputs a 1 when the synchronization signal is detected.

Frequency axis synchronization signal detector 106 detects a predetermined synchronization word from the signal sf ₁ input from the FFT processor 101, and outputs the frequency axis synchronization detection signal Sync_f _y to the output signal switching device 108. The frequency axis synchronization detection signal Sync_f _y, for example, and outputs 0 when the synchronization signal (signal for synchronization) is undetected, and outputs a 1 when the synchronization signal is detected.
The time axis synchronization signal detector 105 and the frequency axis synchronization signal detector 106 should not have hysteresis. In other words, the current OFDM symbol is independently detected without being affected by the detection result of the past symbol.

Abnormal time estimate storage 107, or RF unit when various synchronizing signals are not detected the signal h _e output signal switch 108 when a failure occurs in the (first line receiver RF section 32) outputs It is stored in a memory or the like, and outputs the signal h _e to the output signal switching device 108. Here, as the signal _{h e,} for example, it outputs a 0.

Output signal switch 108 (decision signal inputted from the first line receiver RF unit monitoring and fault detection unit 33) the time axis synchronization detection signal Sync_t _y and the frequency axis synchronization detection signal Sync_f _y a fault notification signal input false based on _1, if there is no abnormal synchronization is not established to the RF unit (the first line receiver RF section 32), the output signal _{h 11} _ _O, as _{h 12} _ _O, h11 channel estimator 103 and h12 channel estimation The channel estimation results _{１１ 11} and ＾ ₁₂ calculated and input by the unit 104 are output (to the MIMO reception processing unit 51).

FIG. 3 shows a truth table based on the above determination.
In the output signal switch 108 of the present embodiment, the inputted false _y is 1 (abnormal) in the case of the output to _{h y1 _ O, h y2 _} O MIMO reception processing unit 51 a _{h e} together as are input was Sync_t _y and Sync_f _y are both 1 (synchronization signal detection), and if abnormality of the RF unit is not _{h y1} _ _O, as _{h y2} _ _O the _{h ^} y1, _h ^ _y2 to MIMO reception processing unit 51 outputs If either synchronization is not established, h _e is output to the MIMO reception processing unit 51 as h _{y1 — O} and h _{y2 — O.} & Indicates logical product in logical algebra.

The MIMO reception processing unit 51 includes sf _{1_delay} , h _{11 — O} , h _{12 — O} , sf 2 — _delay , h _{21 — O} , h _{22 —} from the first system reception baseband unit 34 and the second system reception baseband unit 44. Each of _O is input, and Alamouti decoding is performed according to the following equation and output.
_{S ^ (0) = h 11} _ O * · sf 1_delay (0) + h 12 _ O · sf 1_delay (1) *
^{_{+ H 21 _ O * · sf}} 2_delay (0) + h 22 _ O · sf 2_delay (1) *

_{S ^ (1) = h 12} _ O * · sf 1_delay (0) -h 11 _ O · sf 1_delay (1) *
^{_{+ H 22 _ O * · sf}} 2_delay (0) -h 21 _ O · sf 2_delay (1) *
Note that the number in parentheses after sf _{1_delay} or the like is an index indicating the timing of the OFDM symbol. If the modulation scheme is PSK, etc., in the two equations above, the effective one of the first to fourth term of the right side is (h _yx _ _O is not to h _e) as far as, approximately normal in the process of a subsequent stage Can be demodulated.
When the modulation method is QAM, the following equation should be used instead of the above equation, and when the output of the reception baseband part of one system is substantially cut off, a coefficient that keeps the gain constant should be multiplied. (S ^ (1) is the same)
S ^ (0) = (4 / (D ₂ (1) + D ₂ (0) + D ₁ (1) + D ₁ (0))).
^{_{(H 11 _ O * · sf}} 1_delay (0) + h 12 _ O · sf 1_delay (1) *
^{_{+ H 21 _ O * · sf}} 2_delay (0) + h 22 _ O · sf 2_delay (1) *)
However _{D y ≡1 (if! (False} y) && Sync_t y && Sync_f y),
_{0 (if! (! (False} y) && Sync_t y && Sync_f y))
This equation indicates that D _y = 1 when false _y = 0, Sync_t _y = 1 and Sync_f _y = 1, and D _y = 0 at other times.
When D ₂ (1), D ₂ (0), D ₁ (1), and D ₁ (0) are all 0, S ^ (0) = 0.
If one of the transmission side communication device systems suddenly fails during transmission of a certain OFDM symbol, there is a possibility that a failure such as undetected synchronization is detected in the reception of the OFDM symbol in both of the reception side systems. However, there is no problem because the failure is limited to that symbol and can be restored to the next symbol.

Next, a comparison between this embodiment and a prior art example is shown.
FIG. 4 shows an example of a timing chart when a failure occurs in the present embodiment.
FIG. 5 shows an example of a timing chart when a failure occurs in the prior art example.

  As shown in FIG. 5, in the prior art example, when a failure occurs in the middle of a frame or symbol, it is recognized that the frame is correct at the head of the frame or symbol. Thus, when channel estimation is performed in the baseband part, the process proceeds without obtaining a correct channel estimation result, and the failure of the frame is not recognized until the next frame.

  On the other hand, as shown in FIG. 4, in the present embodiment, when a failure occurs in the middle of a frame, the failure is detected in the channel estimation result output before processing such as FFT calculation and channel estimation is completed. By notifying and outputting, for example, 0 so that it is not apparently received from the receiving antenna of the corresponding system, the MIMO reception processing unit 51 eliminates an adverse effect on one system in which no failure has occurred. It becomes possible.

  As described above, in a radio communication system including two or more receiving units on the receiving side, each receiving unit includes an RF unit (in this example, receiving RF units 32 and 42) and a baseband unit (in this example, receiving base). Band units 34 and 44), and a synthesis unit (in this example, a MIMO reception processing unit 51) that synthesizes output signals from the baseband units of the plurality of receivers described above. A detection unit (in this example, a reception RF unit monitoring / failure detection unit 33, 43) that monitors and detects a failure is provided, and has a function of notifying a failure from the detection unit to the baseband unit. Based on this signal, the output of the baseband unit connected to the RF unit that failed when the RF unit failed is output after the signal output from the RF unit at the time of the failure is processed by the baseband unit Be done Having a function of performing be possible or specific output is cut.

Further, in this embodiment, not only the failure of the RF unit, but also the disconnection of the output of the baseband unit when the time axis synchronization or the frequency axis synchronization detected in the baseband unit occurs or It is possible to make specific output.
In this embodiment, such a wireless communication system is applied to a wireless communication transmission / reception system employing MIMO.

As described above, in this example, in order to prevent outputting an undesirable signal at the baseband output when a failure occurs in the RF unit, before outputting an undesirable signal at the baseband output when a failure occurs in the RF unit, The occurrence of a failure in the RF unit is notified before the processing in the baseband unit is completed, thereby ensuring the signal quality of the entire system even when a failure occurs in a specific RF unit within one frame period. Can do.
In this example, the failure detection result is notified to the MIMO reception processing unit 51 ahead of the channel estimation result, so that it is possible to cope with a sudden change in channel characteristics due to a failure (for example, it is possible to recover from the next symbol). ).

  In addition to STBC, STTC (spatio-temporal trellis code) and other known ones can be used for encoding according to the MIMO scheme, and the method of using channel estimation results in the MIMO reception processing unit 51 is also provided for each code. It is. For example, in STTC, maximum likelihood decoding such as Viterbi is performed, but a channel estimation result is required when generating a replica of a candidate code string.

Note that the wireless communication system of this example includes a transmission-side communication device including two systems of transmission units and a reception-side communication device including two systems of reception units.
In addition, the communication device on the reception side of this example includes two systems of reception units and an all-system reception processing unit (in this example, a MIMO reception processing unit 51). Further, in the receiving-side communication apparatus of this example, the receiving units of each system receive received signal processing means (in this example, the received signals of the antennas 31 and 41, the receiving RF units 32 and 42, and the receiving baseband units 34 and 44). Processing function), channel characteristic estimation means (in this example, channel estimators 103 and 104 in the reception baseband section), failure detection means (in this example, reception RF section monitoring / failure detection sections 33 and 43), Output signal control means (in this example, the output signal switch 108 of the reception baseband unit) is provided. Further, the reception baseband unit of this example includes signal storage means (in this example, an abnormal time estimated value storage 107).

  1 ·· MIMO transmission processing unit, 11 ·· First system transmission baseband unit, 12 ·· First system transmission RF unit, 13 ·· First system transmission antenna, 21 ·· Second system transmission baseband unit, 22・ ・ Second system transmission RF unit, 23 ・ ・ Second system transmission antenna, 31 ・ ・ First system reception antenna, 32 ・ ・ First system reception RF unit, 33 ・ ・ First system reception RF unit monitoring and failure detection 34 .. First system reception baseband unit, 41.. Second system reception antenna, 42.. Second system reception RF unit, 43.. Second system reception RF unit monitoring and failure detection unit, 44. Second system reception baseband unit, 51 ·· MIMO reception processing unit, 101 ·· FFT calculator, 102 ·· Delay unit, 103 ·· hy1 channel estimator, 104 ·· hy2 channel estimator, 105 ·· Time axis Synchronous signal detector 106 .. Frequency axis synchronous signal detector 107 107 Estimated value storage unit 108 Abnormal output signal switch

Claims (2)

In a wireless communication system having a receiving-side communication device including two or more receiving units,
The receiving-side communication device inputs a received signal of each system and an estimation result of channel characteristics from each of the two or more receiving units and the two or more receiving units, and based on the estimation result of the channel characteristics And an all-system reception processing unit for processing the received signal,
Each of the two or more receiving units processes a received signal of each system and outputs it to the all-system receiving processing unit, and estimates channel characteristics based on the received signals of each system. Channel characteristic estimation means for outputting the estimation result to the all-system reception processing unit, failure detection means for detecting a predetermined failure situation, and when the predetermined failure situation is detected by the failure detection means, The predetermined failure situation is detected before the channel characteristic estimation result by the channel characteristic estimation means or instead of the channel characteristic estimation result by the channel characteristic estimation means for the received signal when the failure situation is detected Output signal control means for outputting a signal corresponding to the time to the all-system reception processing unit,
A wireless communication system. The wireless communication system according to claim 1, wherein
A MIMO wireless communication system that wirelessly transmits a signal from a transmission-side communication device including two or more transmission units to a reception-side communication device including two or more reception units,
In the communication device on the receiving side, each of the two or more systems of receiving units serves as a processing unit that constitutes the received signal processing means, an antenna that receives a radio signal, and an RF that processes a signal received by the antenna. And a baseband unit for processing the signal processed by the RF unit,
The failure detection means detects the failure status of the RF unit as the predetermined failure status and outputs the detection result to the baseband unit.
The baseband unit includes the channel characteristic estimation unit, the output signal control unit, and a signal storage unit that stores a signal corresponding to when the predetermined failure condition is detected,
The output signal control unit, when the detection result of the failure status of the RF section from said failure detecting means is input, channel by the channel characteristic estimating unit for a frame of the received signal when said fault condition is detected Before the characteristic estimation result or instead of the channel characteristic estimation result by the channel characteristic estimation unit, the signal stored in the signal storage unit is output to the all-system reception processing unit,
A wireless communication system.

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