JP2013219505A - Communication device, communication system, transmission and reception characteristics calibration method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce traffic and computational complexity, which are required for calibrating the difference in the transmission and reception characteristics of a communication device including a plurality of antennas and performing communication by time division communication.SOLUTION: A transmission path measurement unit 17 measures the transmission path characteristics of each communication path including an analog transmission circuit and an analog reception circuit, in addition to a wireless space. A correction coefficient calculation unit 25 calculates correction coefficients for matching the characteristics of an analog transmission circuit with the characteristics of an analog reception circuit, based on the transmission path characteristics measured by the transmission path measurement unit 17, and a relational expression showing the correction coefficients, when matching the characteristics of an analog transmission circuit with the characteristics of an analog reception circuit, by the expression of transmission path characteristics.

Description

  The present invention relates to a communication device, a communication system, a transmission / reception characteristic calibration method, and a program.

  With increasing demand for wireless communication, further increases in capacity and speed have been demanded within limited wireless resources. A multi-antenna such as an array antenna is an antenna used to meet such a demand, and is used in, for example, a mobile phone base station. With a multi-antenna, high-speed and large-capacity communication can be performed using a plurality of antennas using techniques such as beam forming (EF) and MIMO (Multi Input Multi Output).

  Here, in order to use the beam forming and MIMO techniques, it is necessary to match the antenna characteristics including the analog path in each antenna to be used. Antenna characteristics (specifically, phase, amplitude, delay characteristics; hereinafter referred to as channel characteristics) are different for each channel and change with time due to the influence of temperature and the like. Therefore, it is desirable to perform calibration (calibration) periodically not only at the time of shipment but also in operation.

The calibration of the channel characteristic will be described with reference to FIGS.
FIG. 8 is an explanatory diagram showing an example of beamforming using an array antenna. In the same figure, a communication device having antennas 1008-1 to 1008-m (m is a positive integer) and a communication device having antennas 1019-1 to 1019-n (n is a positive integer) perform wireless communication. ing. In addition, the angle θ represents an angle formed by a direction perpendicular to a plane or a straight line on which the antennas 1008-1 to 1008-m are arranged and the directions of the antennas 1019-1 to 1019-n.

For example, when the radio signals from the antennas 1019-101 to 19-n are received by the antennas 1008-1 to 1008-m, the antenna 1008-1 and the antenna 1008-2 have a transmission path distance according to the angle θ. There is a difference. Specifically, the transmission path of the antenna 1008-2 is longer by d ₁ sin θ with respect to the distance d ₁ between the antenna 1008-1 and the antenna 1008-2. Depending on the difference in the transmission path distance, the antenna 1008-1 and the antenna 1008-2 have different received signal phases and delay amounts. If these received signals are simply superimposed, they interfere with each other. End up.

  Therefore, the received signals at antenna 1008-1 and the received signal at antenna 1008-2 are overlapped after matching the phase and the delay amount, so that these received signals are strengthened. Similarly, the received signals at other antennas are strengthened by matching the phase and delay amount with the received signals at antenna 1008-1.

  Thus, by matching the phase and delay amount of the received signal based on the difference in the transmission path distance according to the angle θ, it is possible to strengthen only the received signal from a specific direction, and from other directions. The influence of received signal interference can be reduced. That is, with this technology, users in different directions can be handled separately, and high-speed and large-capacity communication can be performed while suppressing interference.

  Also, when transmitting a radio signal from the antennas 1008-1 to 1008-m to the antennas 1019-1 to 1019-n, by adjusting the phase and delay amount according to the difference in the transmission path distance for each antenna, Directivity can be given to the radio wave to be transmitted. As a result, stronger radio waves can be transmitted to the communication devices including the antennas 1019-1 to 1019-n, and interference can be reduced to other communication devices.

  Here, if the channel characteristics of the antennas 1008-1 to 1008 -m match, the phase and delay amount are corrected (adjusted) according to the arrival direction (angle θ) of the radio wave using the arrival direction control circuit. ), The received signals at each antenna are strengthened. However, in reality, there are variations in channel characteristics between antennas due to manufacturing errors, circuit and cable characteristic differences, and the like. Furthermore, the channel characteristics change due to the influence of temperature and the like.

  Therefore, in order to strengthen the received signals at each antenna, it is necessary to calibrate the phase amplitude and delay amount according to the difference in channel characteristics and correct the phase and delay amount according to the arrival direction of the radio wave. There is. In the example of FIG. 8, the delay / amplitude phase correction is performed by the antenna calibration unit surrounded by the dotted line, and the characteristics of the respective antennas (transmission / reception channels) are matched. Then, by controlling the signal so as to cancel the transmission path difference caused by the arrival direction θ, the radio wave is given directivity using interference.

  As described above, in order to use beam forming and MIMO, calibration between antennas is essential, and the characteristics of signals transmitted and received by the antenna are made to match the delay amount and phase amplitude change in the transmission path including the antenna. It is necessary to align. Further, such calibration is not limited to being performed only once when the multi-antenna is manufactured, but needs to be repeatedly performed at a certain interval (according to a temperature change or the like). Therefore, an apparatus having a multi-antenna needs to have a calibration function (phase amplitude correction circuit or delay correction circuit). High speed and large capacity communication can be realized by controlling the arrival direction and path for each user with respect to the multi-antenna having matched characteristics in this way.

FIG. 9 is an explanatory diagram showing an example of eigenmode MIMO using an array antenna.
As shown in the figure, the transmission path characteristics H (bold characters indicating matrices and vectors are omitted in the text of the specification) are measured, and singular value decomposition is performed, so that a larger throughput can be obtained using all paths. Can be obtained.

For example, consider a case in which a maximum of L streams are transmitted from the communication device 1021 having the antennas 1008-1 to 1008 -m to the communication device 1022 having the antennas 1019-1 to 1019 -n. Here, L = min (m, n), that is, the smaller value of m and n.
First, the communication device 1022 on the receiving side measures the transmission path characteristic H shown in the equation (1).

Here, the transmission path characteristic H is not only a wireless space but also a path characteristic including an analog unit such as an antenna or a circuit of a communication apparatus (the same applies hereinafter).
Next, the obtained transmission path characteristic H is subjected to singular value decomposition as shown in Expression (2).

Note that the subscript H indicates complex conjugate transposition (the same applies hereinafter). In the following, the subscript T indicates transposition.
Moreover, the matrix D is shown like Formula (3).

Based on the result of this singular value decomposition, a transmission weight E _t and a reception weight E _r ^H are set as shown in FIG. Then, with respect to the transmission signal (the signal before being multiplied by the transmission weight) x, the reception signal (the signal after being multiplied by the reception weight) y is expressed by Expression (4).

Here, as shown in Equation (3), the matrix D is a diagonal matrix. Therefore, the transmission signal x can be reproduced from the reception signal y (obtained for each stream).
Incidentally, the transmission weight _{E t,} and transmits the calculated receiving communication device 1022 to the transmission side communication apparatus 1021 (feedback). Alternatively, the transmission path characteristic H is transmitted (feedback) from the communication device 1022 on the reception side to the communication device 1021 on the transmission side, and the transmission weight _Et is calculated in the communication device 1021 on the transmission side.

Here, in calibration of a multi-antenna, the calibration object required according to communication systems, such as frequency division duplex (FDD) or time division duplex (TDD), differs.
In particular, in a time division duplex communication system, the same frequency is used for transmission and reception (for example, downlink (DL) and uplink (UL)). For this reason, transmission path information necessary for beam forming, eigenmode MIMO, and the like is common for transmission and reception.

  For this reason, if the transmission path characteristics in the transmission path including the analog portion of the communication apparatus as well as the wireless space match between the transmission time and the reception time, transmission can be performed using the transmission path information at the time of reception. it can. Therefore, communication can be performed without the need to constantly notify information such as feedback of transmission path information. However, since there is actually a difference in the transmission / reception characteristics of the array antennas, it is necessary to calibrate the difference of the transmission / reception characteristics for each antenna to match the characteristics.

  A method is known in which this calibration is performed using dedicated hardware and signals and providing a measurement period such as transmission path information. However, since the execution requires complicated signal processing, signal switching, timing control, and the like, the size of the apparatus is increased, the cost is increased, and the development period is increased. In addition, since the communication device on the terminal side such as a mobile phone is more demanding for miniaturization and weight reduction than the case of the base station device, the conditions are further severe.

  Here, in connection with the calibration of the difference between the transmission and reception characteristics, the method for calibrating the communication link in the wireless time division duplex communication system described in Patent Document 1 is for the downlink channel from the access point to the user terminal. Obtain a channel response estimate. This method also obtains a channel response estimate for the uplink channel from the user terminal to the access point. In this method, a correction factor for the access point and a correction factor for the user terminal are determined based on channel response estimation values for the downlink channel and the uplink channel. Here, the correction factor for the access point and the correction factor for the user terminal are used to obtain a calibrated downlink channel response and a calibrated uplink channel response.

  The adaptive array radio base station described in Patent Document 2 includes three or more antenna elements and a signal processing circuit. Then, at the time of calibration, based on the known signal sent from each transmission system and the received signal measured in each transmission system, the difference in the amount of phase rotation and the amount of amplitude fluctuation between the transmission and reception circuits in each transmission system Is estimated. Based on this estimation result, the phase rotation amount of the phase shifter and the amplitude fluctuation amount of the attenuator are set. Thus, the transmission characteristic calibration of the transmission / reception circuit can be performed with a simple and inexpensive configuration without providing a special measurement circuit.

Special table 2008-53034 gazette International Publication No. 00/08777

However, Patent Document 1 and Patent Document 2 do not fully show the reduction in the amount of communication and the amount of calculation required for calibration of the difference between transmission and reception characteristics.
For example, Patent Document 1 shows that the correction rate at the access point may be applied to either the transmission side or the reception side of the access point, or may be applied to the transmission side and the reception side. Further, it is shown that the correction factor in the user terminal may be applied to either the transmission side or the reception side of the user terminal, or may be applied to the transmission side and the reception side. However, Patent Document 1 does not fully show what configuration is used and what calculation can reduce the communication amount and calculation amount required for calibration of the difference between the transmission and reception characteristics.

  Further, Patent Document 2 discloses that a phase shifter and an attenuator for calibrating transmission characteristics of a transmission / reception circuit are provided on the transmission side of the radio base station. Thus, it is not sufficiently shown whether the amount of communication and the amount of calculation required for calibration of the difference in transmission / reception characteristics can be reduced.

  It is an object of the present invention to provide a communication device, a communication system, a transmission / reception characteristic calibration method, and a program that can solve the above-described problems.

  The present invention has been made to solve the above-described problems, and a communication device according to an aspect of the present invention includes an analog transmission circuit and an analog reception circuit in each of a plurality of antennas, the analog transmission circuit, and the analog reception circuit. A transmission / reception changeover switch that realizes communication by time division duplex, and a transmission path measurement unit that measures transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space; A correction coefficient for matching the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit, the transmission path characteristics measured by the transmission path measurement unit, the characteristics of the analog transmission circuit, and the characteristics of the analog reception circuit And a correction coefficient calculation unit that calculates the correction coefficient based on the relational expression shown by the equation of the transmission line characteristic when Based on the correction coefficient positive coefficient calculation unit has calculated, characterized by comprising a correction circuit for correcting to match the characteristics of the characteristics and the analog receiving circuit of the analog transmission circuit.

  In addition, a communication system according to one embodiment of the present invention realizes communication in time division duplex by switching between an analog transmission circuit and an analog reception circuit in each of a plurality of antennas, and the analog transmission circuit and the analog reception circuit. A transmission / reception selector switch, a transmission path measurement unit for measuring transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space, characteristics of the analog transmission circuit, and characteristics of the analog reception circuit The correction coefficient when the transmission line characteristic measured by the transmission line measurement unit, the characteristic of the analog transmission circuit, and the characteristic of the analog reception circuit are matched with each other. A correction coefficient calculation unit that is calculated based on a relational expression represented by a characteristic formula; and the correction coefficient calculation unit that is calculated based on the correction coefficient Characterized by including a plurality of communication apparatus comprising, a correction circuit for correcting to match the characteristics of the characteristics and the analog receiving circuit of the analog transmission circuit.

  According to another aspect of the present invention, there is provided a method for calibrating transmission / reception characteristics, wherein an analog transmission circuit and an analog reception circuit in each of a plurality of antennas, and the analog transmission circuit and the analog reception circuit are switched to perform communication in time division duplex. A transmission / reception characteristic calibration method for a communication apparatus comprising: a transmission / reception changeover switch for realizing transmission path measurement for measuring transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space A correction coefficient for matching the characteristics of the analog transmitter circuit and the analog receiver circuit, the transmission path characteristics measured in the transmission path measurement step, the characteristics of the analog transmitter circuit, and the analog reception The correction coefficient when the circuit characteristics are matched is calculated based on the relational expression shown by the transmission path characteristic formula. A correction coefficient calculation step; and a correction step for performing correction to match the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit based on the correction coefficient calculated in the correction coefficient calculation step. It is characterized by.

  The program according to one aspect of the present invention is a transmission / reception that realizes communication in time division duplex by switching between an analog transmission circuit and an analog reception circuit in each of a plurality of antennas, and the analog transmission circuit and the analog reception circuit. A transmission path measuring step for measuring transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space in a computer that calibrates the transmission / reception characteristics of the communication device including the changeover switch; Correction coefficient for matching the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit, the transmission path characteristics measured in the transmission path measurement step, the characteristics of the analog transmission circuit, and the characteristics of the analog reception circuit Is calculated based on the relational expression shown by the equation of the transmission path characteristic. A correction coefficient calculation step, and a correction step for performing correction to match the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit based on the correction coefficient calculated in the correction coefficient calculation step. It is a program.

  According to the present invention, it is possible to reduce the amount of communication and the amount of calculation required for calibration of the difference between transmission and reception characteristics.

It is explanatory drawing which shows the example of schematic structure of the radio | wireless communications system which communicates by a time division duplex. It is a block diagram which shows schematic structure of the base station apparatus and mobile station apparatus which have the circuit for a calibration in the path | route of a transmission side. It is a block diagram which shows schematic structure of the communication system in one Embodiment of this invention. It is explanatory drawing which shows the example of the transmission / reception relationship between antennas of the communication system of the 1st modification in this embodiment. It is explanatory drawing which shows the example of arrangement | positioning of the antenna of the communication system of the 2nd modification in this embodiment. It is a block diagram which shows schematic structure of the base station apparatus in the modification. It is a block diagram which shows the minimum structure of this invention among each part of the base station apparatus in the modification. It is explanatory drawing which shows the example of the beam forming using an array antenna. It is explanatory drawing which shows the example of eigenmode MIMO using an array antenna.

Embodiments of the present invention will be described below with reference to the drawings.
First, as a precondition for calibration performed in the present invention, time division duplex using a multi-antenna (a plurality of antennas) in an ideal state where there is no characteristic difference between transmission and reception circuits will be described with reference to FIG.
FIG. 1 is an explanatory diagram illustrating a schematic configuration example of a wireless communication system that performs communication using time division duplex. In the figure, a wireless communication system 800 includes a base station device 810 and a mobile station device 820. In the following, for convenience of explanation, the base station apparatus and the mobile station apparatus will be described in order to call the radio space as uplink or downlink, but in other cases (for example, between fixed communication apparatuses, The case of a mobile communication apparatus) is the same as the following description.

The base station apparatus 810 includes m (m is a positive integer) antennas 8-1 to 8-m that constitute a smart antenna, a digital / analog (DA) conversion circuit 11a, and an analog / digital (Analog). / Digital; AD) conversion circuit 12a, transmission / reception selector switch (Switch; SW) 13a, and baseband (BB) unit 821.
The mobile station device 820 includes n (n is a positive integer) antennas 19-1 to 19-n, a digital / analog conversion circuit 11b, an analog / digital conversion circuit 12b, and a transmission / reception changeover switch 13b that constitute a smart antenna. And a baseband portion 822.

In the base station device 810, the baseband unit 821, the digital / analog conversion circuit 11a, the analog / digital conversion circuit 12a, and the transmission / reception selector switch 13a are configured independently for each of the antennas 8-1 to 8-m. Has been. In other words, m sets of these circuits and the antennas 8-1 to 8-m are connected on a one-to-one basis.
In the mobile station device 820, the baseband unit 822, the digital / analog conversion circuit 11b, the analog / digital conversion circuit 12b, and the transmission / reception switch 13b are independent of each of the antennas 19-1 to 19-n. It is configured. In other words, these n sets of circuits and the antennas 19-1 to 19-n are connected one-to-one.

Hereinafter, a circuit from the digital / analog conversion circuit to the antenna is referred to as an “analog transmission circuit”, and a circuit from the antenna to the analog / digital conversion circuit is referred to as an “analog reception circuit”. Further, the analog transmission circuit and the analog reception circuit are collectively referred to as “analog section”.
For example, in the base station apparatus 810, the digital / analog conversion circuit 11a to the antennas 8-1 to 8-m correspond to the analog transmission circuit, and the antennas 8-1 to 8-m to the analog / digital conversion circuit 12a. Corresponds to analog receiver circuit. Moreover, the part which put these together corresponds to an analog part. In the mobile station device 820, the digital / analog conversion circuit 11b to the antennas 19-1 to 19-n correspond to analog transmission circuits, and the antennas 19-1 to 19-n to the analog / digital conversion circuit 12b. Corresponds to analog receiver circuit. Moreover, the part which put these together corresponds to an analog part.

The base station apparatus 810, a digital / analog converter circuit 11a has a transmission signal x _t which is converted into an analog signal, and transmits using the antenna 8-1 to 8-m to generate the base band unit 821 based on the communication data . The base station apparatus 810 receives the antenna 8-1 to 8-m are the received signals _{y r} outputted to the analog / digital converter 12a through the transmission and reception change-over switch 13a, and outputs to the baseband unit 821 Extract communication data.
The transmission / reception change-over switch 13a realizes time division duplex by switching transmission / reception. Therefore, the base station apparatus 810 cannot perform transmission / reception at the same time.

Mobile station apparatus 820, a digital / analog converter circuit 11b is a transmission signal _{x r} which is converted into an analog signal, and transmits using the antenna 19 - 1 through 19-n to generate the base band section 822 on the basis of the communication data . The mobile station device 820 receives the antenna 19 - 1 through 19-n is, the received signal _{y t} outputted to the analog / digital converter circuit 12b through the reception switching switch 13b, and outputs to the baseband unit 822 Extract communication data.
The transmission / reception change-over switch 13b realizes time division duplex by switching transmission / reception. Therefore, the mobile station apparatus 820 cannot perform transmission / reception simultaneously.

Here, let us consider a case where there is no characteristic difference between the transmission / reception circuits (analog transmission circuit and analog reception circuit) in both the base station apparatus 810 and the mobile station apparatus 820. In this case, the transmission path characteristics in the transmission path including the analog portion match between the transmission direction and the reception direction. Therefore, the transmission path characteristic H = H _t for the downlink from the base station apparatus 810 side to the mobile station apparatus 820 side and the transmission path characteristic H _r for the uplink from the mobile station apparatus 820 side to the base station apparatus 810 side are As shown in equation (5), there is a transposition relationship.

As described above, the subscript H indicates complex conjugate transposition, and the subscript T indicates transposition. The matrix H is an n-row × m-column matrix as shown in the equation (1).
In this way, the transmission path characteristics for the downlink and the transmission and characteristics for the uplink are transposed, so various characteristics (not only transmission path characteristics but also transmission and reception weights) can be easily converted between transmission and reception. is there. For example, if the base station apparatus 810 transposes and transmits the reception weight obtained in the uplink, a desired transmission beam can be formed as it is. As described above, the transmission path characteristic H is a path characteristic including not only a wireless space but also an analog unit such as an antenna or a circuit of a communication apparatus.
Here, a transmission signal x _t in the uplink and received signal y _t, denoted column vector as in each formula (6).

Then, the relationship between the transmission signal x _t and the reception signal y _t is expressed as in Expression (7).

Similarly, a transmission signal x _r in the downlink and the received signal y _r, denoted column vector as in each formula (8).

Then, the relationship between the transmission signal _xr and the reception signal yr is _expressed as in Expression (9).

Next, as a premise of calibration performed in the present invention, a calibration method in the case where there is a characteristic difference between transmission and reception circuits will be described with reference to FIG. By applying the present invention, it is possible to reduce the communication amount and the calculation amount in the calibration described in FIG.
FIG. 2 is a configuration diagram showing a schematic configuration of a base station apparatus and a mobile station apparatus having a calibration circuit on the transmission side path. In the figure, a wireless communication system 900 includes a base station device 910 and a mobile station device 920.

  Similarly to the base station apparatus 810 (FIG. 1), the base station apparatus 910 includes m (m is a positive integer) antennas 8-1 to 8-m that constitute a smart antenna, and digital / analog (DA). ) Conversion circuit 11a, analog / digital (AD) conversion circuit 12a, transmission / reception selector switch (Switch; SW) 13a, and baseband (BB) unit 921. The base station apparatus 910 performs transmission / reception using the antennas 8-1 to 8-m. The transmission / reception change-over switch 13a realizes time division duplex by switching transmission / reception.

  Similar to the mobile station apparatus 820 (FIG. 1), the mobile station apparatus 920 includes n (n is a positive integer) antennas 19-1 to 19-n, a digital / analog conversion circuit 11b, and an analog / Digital conversion circuit 12b, transmission / reception selector switch 13b, and baseband unit 822. And the mobile station apparatus 920 transmits / receives using the antennas 19-1 to 19-n. The transmission / reception change-over switch 13b realizes time division duplex by switching transmission / reception.

On the other hand, unlike the example of FIG. 1, the transmission / reception characteristic difference B of the analog part is indicated by a circuit 31 in the path on the transmission side of the base station apparatus 910. In addition, a circuit 32 indicating a transmission / reception characteristic difference U of the analog unit is shown on the transmission side path of the mobile station device 920. In FIG. 2, it is assumed that the transmission / reception characteristic difference of the analog unit is in the transmission unit (analog transmission circuit). That is, the characteristic difference on the transmission side when the characteristic on the reception side is used as a reference is shown in the path on the transmission side.
The base station apparatus 910 includes a correction circuit 9a for correcting (calibrating) the transmission / reception characteristic difference B. Similarly, the mobile station device 920 includes a correction circuit 9b for correcting (calibrating) the transmission / reception characteristic difference U.

  Here, the transmission / reception characteristic difference B can be expressed as a coefficient for each of the antennas 8-1 to 8-m, and is represented by a diagonal matrix as shown in Expression (10).

Here, b _{1 to} b _m are coefficients for the antennas 8-1 to 8-m, respectively, and the phase and amplitude as the difference in characteristics between the analog transmission unit and the analog reception unit are expressed using, for example, complex numbers. Shown in format.
Similarly, the transmission / reception characteristic difference U can be expressed as a coefficient for each of the antennas 19-1 to 19-n and is represented by a diagonal matrix as in Expression (11).

Here, u ₁ ~u _n are each a coefficient for the antenna 19 - 1 through 19-n, expressed using the phase and amplitude, for example, the complex numbers as a difference in the characteristics of the analog transmission and analog receiver Shown in format.
Also, the downlink transmission path characteristic from the base station apparatus 910 to the mobile station apparatus 920 is expressed by the equation (12) with respect to the downlink transmission path characteristic H in the ideal state.

That is, the matrix H indicates a common component of the downlink and uplink among the transmission path characteristics, and the matrix B is a differential component (analog transmission circuit characteristics and analog reception circuit) in the transmission / reception circuit in the base station apparatus 910. The difference from the characteristics of
Moreover, channel characteristics of the up-link from the mobile station apparatus 920 to base station apparatus 910 is as shown in equation (13) to the channel characteristics H ^T uplink in an ideal state.

From Expression (12) and Expression (13), Expression (14) indicating the relationship between the transmission / reception characteristic difference B and U is obtained.
Here, the matrix H ^T, of the channel characteristics, show the common components of the downlink and uplink, the matrix U is in the mobile station apparatus 920, and the characteristics of the difference component (analog transmission circuits receive circuit analog (Difference with the characteristics of the receiving circuit).

Moreover, when indicating the correction the correction circuit 9a is performed by the correction coefficient B _c, channel characteristics after the correction in the uplink (after calibration run) becomes H _t B _c. Moreover, when indicating the correction the correction circuit 9b is performed by the correction factor U _c, channel characteristics after the correction in the downlink (after calibration execution) is a U _c H _r ^T.
When the transmission / reception transmission path characteristics match in the correction (that is, when the difference in transmission characteristics of the transmission / reception circuits is eliminated), the relationship of Expression (15) is established.

While this equation (15) shows m · n relational expressions, there are m + n variables included in the expression (15). However, the value of the variable is not uniquely determined, and a constant multiple term for B and U remains. Therefore, the matrix B _c is defined as in Expression (16). That is, the correction coefficient is set so as to satisfy Expression (16).

Here, c is an indefinite coefficient. From Expression (15) and Expression (16), U _c is expressed as Expression (17) using an indefinite coefficient c.

  This calibration method is different from the calibration between array antennas that is normally performed. That is, the characteristic is that the transmission characteristics and the reception characteristics of each antenna are made to coincide with each other, instead of making the characteristics coincide between the antennas. By matching the transmission / reception circuit characteristics, the transmission / reception transmission path characteristics match when the transmission path characteristics are defined including analog signal paths such as antennas and RF circuits. Thereby, in the time division duplex communication system, the downlink and uplink transmission path characteristics are common, and transmission and reception transmission path characteristics (in particular, each of the base station and the mobile station) (in particular, each of the base station and the mobile station) It is possible to measure transmission path characteristics during transmission. Therefore, there is no need to notify the feedback of the transmission path characteristics.

  Note that calibration for matching transmission / reception characteristics and calibration for matching characteristics between antennas can be used in combination. Here, only the calibration for matching the transmission / reception characteristics does not have the characteristics as an array antenna at the antenna end, so that the arrival direction of radio waves in real space cannot be determined (detected). That is, even if the communication partner can be confirmed, it cannot be known in which direction it actually exists. Therefore, by performing calibration for matching the characteristics between the antennas in addition to calibration for matching the transmission / reception characteristics, the radio wave arrival direction can be detected.

FIG. 3 is a configuration diagram showing a schematic configuration of a wireless communication system in an embodiment of the present invention. In FIG. 1, a communication system 100 includes a base station device 110 and a mobile station device 120. Base station apparatus 110 includes antennas 8-1 and 8-2, correction circuits 9a and 9b, digital / analog conversion circuits 11a and 11b, analog / digital conversion circuits 12a and 12b, and transmission / reception changeover switches 13a and 13b. It comprises. The mobile station device 120 includes correction circuits 9c and 9d, digital / analog conversion circuits 11c and 11d, analog / digital conversion circuits 12c and 12d, transmission / reception changeover switches 13c and 13d, antennas 19-1 and 19-2, It comprises.
The application range of the present invention is not limited to the combination of the base station apparatus and mobile station configuration shown in FIG. For example, the present invention can be applied to communication between fixed communication devices and communication between mobile communication devices.

As shown in FIG. 3, base station apparatus 110 and mobile station apparatus 120 each include two antennas (antenna elements) and perform communication using 2 × 2 MIMO. There are four combinations of antenna elements, and for each, the downlink transmission path characteristics _{ht, 11} , _{ht, 12} , _{ht, 21} , _{ht, 22} from the base station apparatus 110 to the mobile station apparatus 120 are: From equation (1), equation (10) and equation (12), it is shown as equation (18).

However, the transmission path characteristic _{ht, 11} is the transmission path characteristic of the path including the analog part from the antenna 8-1 side to the antenna 19-1 side. Further, the transmission path characteristic _{ht, 12} is a transmission path characteristic of a path including an analog part from the antenna 8-2 side to the antenna 19-1 side. Further, the transmission path characteristic _{ht, 21} is the transmission path characteristic of the path including the analog portion from the antenna 8-1 side to the antenna 19-2 side. Further, the transmission path characteristic _{ht, 22} is a transmission path characteristic of a path including an analog portion from the antenna 8-2 side to the antenna 19-2 side.

Further, transmission / reception transmission line characteristics h _{r, 11} , h _{r, 12} , h _{r, 21} , h _{r, 22} are _expressed by the equation (19) from the equations (1), (11), and (13). Shown in

However, the transmission path characteristics hr _{, 11} are the transmission path characteristics of the path including the analog portion from the antenna 19-1 side to the antenna 8-1 side. The transmission path characteristics hr _{, 12} are the transmission path characteristics of the path including the analog part from the antenna 19-2 side to the antenna 8-1 side. Further, the transmission path characteristics hr _{, 21} are the transmission path characteristics of the path including the analog portion from the antenna 19-1 side to the antenna 8-2 side. The transmission path characteristics hr _{, 22} are the transmission path characteristics of the path including the analog part from the antenna 19-2 side to the antenna 8-2 side.

In order to make the characteristics of the transmission / reception paths coincide with each other, it is only necessary to satisfy Expression (20) for correction coefficients b _{c, 1} , b _{c, 2} , u _{c, 1} , u _{c, 2 from} Expression (15).

An example of a specific correction coefficient determination method is shown below. First, the correction coefficient b _{c, 1} is set (defined) as in Expression (21).

Then, from the equation (20), the correction coefficient uc _{, 1} is represented by the equation (22).

Further, the correction coefficient b _{c, 2} is obtained as shown in Equation (23).

Further, the correction coefficient uc _{, 2} is obtained as in Expression (24).

As described above, all the correction coefficients can be obtained with the indefinite coefficient c fixed. Here, the term including the transmission path characteristics h _{t, 22} , h _{r, 22} in the equation (20) is redundant and basically not necessary. In the case of 2 × 2 MIMO, the correction coefficient can be determined by using any three of the four relational expressions shown in Expression (20). Note that redundant expressions may be used for averaging or the like in order to reduce variations in correction coefficients due to measurement errors.

The correction circuit 9a performs correction (calibration) based on the obtained correction coefficients b _{c, 1} and b _{c, 2 so} that the characteristics of the analog transmission circuit coincide with the characteristics of the analog reception circuit. Specifically, the correction circuit 9a corrects each of the antennas 8-1 and 8-2 to a transmission signal in the digital transmission unit (that is, the stage before the digital / analog conversion circuit converts the transmission signal into analog). Multiply coefficients (adjust phase and amplitude). As a result, the correction circuit 9a matches the characteristics of the analog transmission circuit in the base station apparatus 110 with the characteristics of the analog reception circuit.

Further, the correction circuit 9b performs correction (calibration) to match the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit based on the obtained correction coefficients uc _{, 1} and uc _{, 2} . Specifically, the correction circuit 9b corrects each of the antennas 19-1 and 19-2 into a transmission signal in the digital transmission unit (that is, the stage before the digital / analog conversion circuit converts the transmission signal into analog). Multiply coefficients (adjust phase and amplitude). As a result, the correction circuit 9b matches the characteristics of the analog transmission circuit in the mobile station device 120 with the characteristics of the analog reception circuit.

The transmission path characteristics are measured by transmitting and receiving pilot signals between the base station apparatus 110 and the mobile station apparatus 120, and calculating a correlation value between the received pilot signal and the original pilot signal on the receiving side. Do. For example, when measuring the transmission path characteristics _{ht, 11} , first, the base station apparatus 110 transmits a pilot signal from the antenna 8-1. Then, the mobile station apparatus 120 calculates a correlation value between the pilot signal received by the antenna 19-1 and the original pilot signal (the same pilot signal generated inside the mobile station apparatus 120 as that at the time of transmission). Thus, the transmission path characteristics are obtained.

By fixing the indefinite coefficient in this way, the correction calculation can be simplified. In this case, h _{r, 11} / hr _{, 12} is transmitted (feedback) from the base station apparatus 110 to the mobile station apparatus 120 as a parameter obtained from the transmission path characteristics, and from the mobile station apparatus 120 to the base station apparatus 110, What is necessary is just to transmit _{ht, 11} / ht _12,12 . Thus, it is sufficient to transmit one parameter value from each of the base station apparatus 110 to the mobile station apparatus 120 and from the mobile station apparatus 120 to the base station apparatus 110, and the amount of communication can be reduced. Further, as shown in the equations (21) to (24), the correction coefficient can be calculated by a simple calculation using the transmission path characteristics, so that the calculation amount can be reduced.

Next, the communication system 200 which is the 1st modification of the communication system 100 in this embodiment is demonstrated.
FIG. 4 is an explanatory diagram illustrating an example of a transmission / reception relationship between antennas in the communication system 200 according to the present modification. In the figure, a base station apparatus 210 includes three antennas 8-1 to 8-3, and a mobile station apparatus 220 includes three antennas 19-1 to 19-3. Base station apparatus 210 and mobile station apparatus 220 communicate with each other using 3 × 3 MIMO.

The configuration of the analog unit connected to each antenna is the same as that of the communication system 100 (FIG. 3), and illustration and description thereof are omitted.
Further, as described for the communication system 100, the application range of the present invention is not limited to the combination of the base station apparatus and the mobile station configuration shown in FIG. For example, the present invention can be applied to communication between fixed communication devices and communication between mobile communication devices.

As shown in FIG. 4, there are nine combinations of transmission / reception antennas. Of these, for example, if transmission path estimation is performed for five sets indicated by solid arrows, all six correction coefficients can be obtained including indefinite coefficients. Here, when obtaining the correction coefficients, it is necessary to select five sets of formulas in combinations that determine the relationship between all six correction coefficients.
Specifically, first, Expression (25) is obtained for the relationship between the transmission path characteristic and the correction coefficient, similarly to Expression (20) in the case of 2 × 2 MIMO.

Here, the transmission path characteristics h _{t, ik} (i is a positive integer of 1 ≦ i ≦ 3, k is a positive integer of 1 ≦ k ≦ 3) from the antenna 8-k side to the antenna 19-i side. The transmission path characteristics of the path including the analog part. Further, the transmission path characteristics h _{r, ki} (k is a positive integer of 1 ≦ k ≦ 3, i is a positive integer of 1 ≦ i ≦ 3) from the antenna 19-i side to the antenna 8-k side, It is the transmission-line characteristic of the path | route containing an analog part.

Also, b ₁ , b ₂ , b ₃ (see Expression (10)) in the matrix B indicate transmission / reception characteristic differences of the analog units related to the antennas 8-1, 8-2, and 8-3, respectively. Further, u ₁ , u ₂ , u ₃ (see Expression (11)) in the matrix U indicate transmission / reception characteristic differences of the analog units related to the antennas 19-1, 19-2, 19-3, respectively.

Further, correction coefficients b _{c, 1} , b _{c, 2} , b _{c, 3} indicate the correction coefficients of the analog part related to the antennas 8-1, 8-2, 8-3, respectively. These correction coefficients b _{c, 1} , b _{c, 2} , b _{c, 3} are set so as to satisfy Expression (16) as described above. Further, correction coefficients u _{c, 1} , u _{c, 2} , u _{c, 3} indicate analog correction coefficients for the antennas 19-1, 19-2, 19-3, respectively. These correction coefficients u _{c, 1} , u _{c, 2} , u _{c, 3} are set so as to satisfy Expression (17) as described above.

From the equation (25), _{ht, 11bc, 1} = uc _{, 1hr, 11} , _{ht, 12bc, 2} = uc _{, 1hr, 21} , ..., _{ht, 33} Nine relational expressions of b _{c, 3} = u _{c, 3} hr _{, 33} are obtained.

Further, any one of the correction coefficients b _{c, 1} , b _{c, 2} , b _{c, 3} , u _{c, 1} , u _{c, 2} , u _{c, 3} is set to the transmission line characteristic as in the case of the equation (21). Set (define) using. At that time, among the above nine relational expressions, in the relational expression in which the set correction coefficient appears, the transmission path characteristics appearing on the opposite side of the correction coefficient are used.
For example, in the relational expression h _{t, 11} b _{c, 1} = u _{c, 1} hr _{, 11} , the correction coefficient b _{c, 1} appears on the left side, whereas on the right side, the transmission path characteristic h _{r , 11} appear. Therefore, as in the case of the 2 × 2 MIMO communication system 100 (FIG. 3), the correction coefficient b _{c, 1} can be defined as in Expression (21).

Next, using a relational expression in which a correction coefficient for which a value has already been set and a correction coefficient for which a value has not yet been set appear, the value of a correction coefficient for which a value has not been set has already been set. It is set using the correction coefficient value and the transmission path characteristics. This is performed until all correction coefficient values are set.
For example, based on the relational expression “h _{t, 11} b _{c, 1} = u _{c, 1} h _{r, 11} ” and the value “h _{r, 11} ” of the correction coefficient b _{c, 1} , the 2 × 2 MIMO communication system 100 ( As in the case of FIG. 3), the value of the correction coefficient uc _{, 1} can be obtained (set) as shown in Expression (22).
In this way, for example, the correction coefficients b _{c, 1} , b _{c, 2} and b _{c, 3} shown in Expression (26) can be obtained.

Further, for example, correction coefficients uc _{, 1} , uc _{, 2} , and uc _{, 3} shown in Expression (27) can be obtained.

  As in the case of the 2 × 2 MIMO communication system 100 (FIG. 3), the redundant expression may be used for processing such as averaging in order to reduce variations in correction coefficients due to measurement errors.

As in the case of the 2 × 2 MIMO communication system 100 (FIG. 3), the correction calculation can be simplified by fixing the indefinite coefficient in this way. In this case, h _{r, 11} / hr _{, 12} , hr _{, 11} / hr _{, 13} may be transmitted (feedback) from the base station apparatus 210 to the mobile station apparatus 220 as parameters obtained from the transmission path characteristics. . Moreover, what is necessary is just to transmit _{ht, 11} / _{ht, 12} , _{ht, 11} / _{ht, 13} from the mobile station apparatus 220 to the base station apparatus 210. FIG. In this way, it is only necessary to transmit two parameter values from the base station apparatus 210 to the mobile station apparatus 220, and from the mobile station apparatus 220 to the base station apparatus 210, and the amount of communication can be reduced. Further, as shown in Expression (26) and Expression (27), the correction coefficient can be calculated by a simple calculation using the transmission path characteristics, so that the amount of calculation can be reduced.

Next, the communication system 100 according to the present embodiment and the communication system 300 that is a second modified example of the communication system 200 according to the first modified example will be described.
FIG. 5 is an explanatory diagram illustrating an arrangement example of antennas in the communication system 300 according to the present modification. In the figure, a base station apparatus 310 includes m (m is a positive integer) antennas 8-1 to 8-m, and a mobile station apparatus 320 includes n (n is a positive integer) antennas 19-1. ~ 19-n. Base station apparatus 310 and mobile station apparatus 320 communicate with each other using mxn MIMO.

The configuration of the analog unit connected to each antenna is the same as that of the communication system 100 (FIG. 3), and illustration and description thereof are omitted.
Moreover, as described for the communication system 100, the application range of the present invention is not limited to the combination of the base station apparatus and the mobile station configuration shown in FIG. For example, the present invention can be applied to communication between fixed communication devices and communication between mobile communication devices.

In this case, there are m · n combinations of transmission / reception antennas. Among them, if transmission path estimation is performed for m + n−1 equations in which the relationship between all m + n correction coefficients is determined, the correction coefficient can be obtained in a form including an indefinite coefficient.
Specifically, first, Expression (28) is obtained for the relationship between the transmission path characteristic and the correction coefficient, similarly to Expression (20) in the case of 2 × 2 MIMO and Expression (25) in the case of 3 × 3 MIMO.

Here, the transmission line characteristics h _{t, ik} (i is a positive integer of 1 ≦ i ≦ n, k is a positive integer of 1 ≦ k ≦ m) from the antenna 8-k side to the antenna 19-i side. The transmission path characteristics of the path including the analog part. Further, the transmission line characteristics h _{r, ki} (k is a positive integer of 1 ≦ k ≦ m, i is a positive integer of 1 ≦ i ≦ n) from the antenna 19-i side to the antenna 8-k side, It is the transmission-line characteristic of the path | route containing an analog part.

Further, _b 1, ... in the matrix B, _{b m} (see equation (10)), respectively, the antenna 8-1, ..., indicating the reception characteristic difference of the analog portion about 8-m. In addition, u ₁ ,..., U _n (see Expression (11)) in the matrix U indicate transmission / reception characteristic differences of the analog units with respect to the antennas 19-1,.

Further, correction coefficients b _{c, 1} ,..., B _{c, m} indicate correction coefficients of the analog part related to the antennas 8-1,. These correction coefficients b _{c, 1} ,..., B _{c, m} are set so as to satisfy Expression (16) as described above. In addition, correction coefficients u _{c, 1} ,..., U _{c, n} indicate correction coefficients of the analog unit related to the antennas 19-1,. These correction coefficients u _{c, 1} ,..., U _{c, n} are set to satisfy Expression (17) as described above.

From equation (28), _{ht, 11bc, 1} = uc _{, 1hr, 11} , _{ht, 12bc, 2} = uc _{, 1hr, 21} , ..., _{ht, nm} m · n relational expressions of b _{c, m} = u _{c, n} hr _{, mn} can be obtained.

Further, the correction coefficient _{b c, 1, ···, b} c, m, u c, 1, ···, u c, one of _n, using the channel characteristics as in the case of formula (21) To set (define). At this time, of the above m · n relational expressions, in the relational expression in which the set correction coefficient appears, the transmission path characteristic appearing on the opposite side of the correction coefficient is used.
For example, in the relational expression h _{t, 11} b _{c, 1} = u _{c, 1} hr _{, 11} , the correction coefficient b _{c, 1} appears on the left side, whereas on the right side, the transmission path characteristic h _{r , 11} appear. Therefore, as in the case of the 2 × 2 MIMO communication system 100 (FIG. 3), the correction coefficient b _{c, 1} can be defined as in Expression (21).

Next, using a relational expression in which a correction coefficient for which a value has already been set and a correction coefficient for which a value has not yet been set appear, the value of a correction coefficient for which a value has not been set has already been set. It is set using the correction coefficient value and the transmission path characteristics. This is performed until all correction coefficient values are set.
For example, based on the relational expression “h _{t, 11} b _{c, 1} = u _{c, 1} h _{r, 11} ” and the value “h _{r, 11} ” of the correction coefficient k _{c, 1, the 2} × 2 MIMO communication system 100 ( As in the case of FIG. 3), the value of the correction coefficient uc _{, 1} can be obtained (set) as shown in Expression (22).

Further, the relational expression “h _{t, 1 k} b _{c, k} = u _{c, 1} hr _{, k1} ” (k is a positive integer of 1 ≦ k ≦ m) and the value “h _{t, 1} ” of the correction coefficient u _{c, 1 . 11} ” _, the value of the correction coefficient b _{c, k} can be obtained as“ hr _{, k1 ht , 11} / _{ht, 1k} ”.
Also, the relational expression _{"h t, i1 b c, 1} = u c, i h r, 1i " (i is a positive integer of 1 ≦ i ≦ n) and the correction coefficient _{b c, 1} value _{"h r, 11} ” _, the value of the correction coefficient uc _{, i} can be obtained as“ _{ht, i1} hr _{, 11} / hr _{, 1i} ”.

In this way, for example, correction coefficients b _{c, 1} ,..., B _{c, m} shown in Expression (29) can be obtained.

In addition, for example, correction coefficients u _{c, 1} ,..., U _{c, n} shown in Expression (30) can be obtained.

  As in the case of the 2 × 2 MIMO communication system 100 (FIG. 3), the redundant expression may be used for averaging or the like in order to reduce the variation in the correction coefficient due to the measurement error.

As in the case of the 2 × 2 MIMO communication system 100 (FIG. 3) and the 3 × 3 MIMO communication system 200 (FIG. 4), the correction calculation can be simplified by fixing the indefinite coefficient in this way. In this case, if parameters hr _{, 11} / hr _{, 12} ,..., _{Hr, 11} / hr _{, 1n} are transmitted from the base station apparatus 310 to the mobile station apparatus 320 as parameters obtained from the transmission path characteristics. Good. Moreover, what is necessary is _just to transmit _{ht, 11} / _{ht, 12} , ..., _{ht, 11} / _{ht, 1m} from the mobile station apparatus 320 to the base station apparatus 310. FIG. In this way, n−1 parameter values may be transmitted from the base station apparatus 310 to the mobile station apparatus 320, and m−1 parameter values may be transmitted from the mobile station apparatus 320 to the base station apparatus 310. The amount of communication can be reduced. Further, as shown in Expression (29) and Expression (30), the correction coefficient can be calculated by a simple calculation using the transmission path characteristics, so that the amount of calculation can be reduced.

FIG. 6 is a configuration diagram illustrating a schematic configuration of the base station apparatus 310. In the figure, a base station apparatus 310 includes a plurality of antennas 8-1 to 8-m, and transmits and receives a correction circuit 9a, a digital / analog conversion circuit 11a, and an analog / digital conversion circuit 12a for each antenna. Changeover switches 13 a and 13 b and a register 26 are provided. The baseband unit 321 includes a pilot signal generation unit 14, a modulation unit 15, a demodulation unit 16, a transmission path measurement unit 17, memories 23 and 24, a correction coefficient calculation unit 25, and a mapping unit 27. . Similarly to the case of FIG. 3, the transmission / reception characteristic difference B of the analog portion is indicated by a circuit 31.
In addition, although the base station apparatus 310 is demonstrated here, it is the same also about the mobile station apparatus 320. FIG.

  In the digital unit of the base station apparatus 310 shown in the baseband unit 321, the pilot signal generation unit 14 generates a pilot signal (reference signal). Also, the modulation unit 15 modulates transmission data to generate a transmission signal. At this time, the modulation unit 15 modulates the transmission data by including the parameter of the transmission line information calculated from the transmission line characteristic Hr measured by the transmission line measurement unit 17.

The mapping unit 27 maps the pilot signal generated by the pilot signal generation unit 14 and the transmission data modulated by the modulation unit 15.
Then, the correction circuit 9a performs correction for matching the transmission / reception characteristics of the analog unit on the signal (digital transmission signal) mapped by the mapping unit 27 based on the correction coefficient stored in the register 26. Specifically, the correction circuit 9a corrects the transmission / reception characteristic difference B of the analog unit by multiplying the signal mapped by the mapping unit 27 by the correction coefficient Bc (that is, adjusting the phase and amplitude).

  The digital / analog conversion circuit 11a converts the signal corrected by the correction circuit 9a into an analog signal, thereby generating an analog transmission signal, and the mobile station via the transmission / reception changeover switch 13a and the antennas 8-1 to 8-m. Transmit to device 320 (FIG. 5).

Further, when the antennas 8-1 to 8-m receive a communication signal from the mobile station apparatus 320, the analog / digital conversion circuit 12a acquires the communication signal via the transmission / reception changeover switch 13a and performs digital conversion.
In the digital unit of the base station apparatus 310 shown in the baseband unit 321, the transmission path measurement unit 17 converts the pilot signal generated by the pilot signal generation unit 14 and the analog / digital conversion circuit 12 a to digital conversion. Transmission path estimation is performed using a pilot signal included in the received signal to determine transmission path characteristics Hr. The memory 24 records (stores) the transmission line characteristic Hr obtained by the transmission line measurement unit 17 as Hr (t) together with the measurement time t.

  The demodulator 16 demodulates the received signal digitally converted by the analog / digital conversion circuit 12a to extract communication data. Then, the demodulator 16 uses the parameter indicating the transmission line characteristic (value calculated from the transmission line characteristic Ht) included in the extracted demodulated data and sent as feedback information from the mobile station apparatus to the information on the measurement time t. At the same time, it is recorded (stored) in the memory 23.

The correction coefficient calculation unit 25 stores the transmission time characteristic Hr recorded in the memory 24 and the parameters recorded in the memory 23 in association with the measurement time t (for example, stored in association with the measurement time like Hr (t)). (For example, a combination having a time difference equal to or less than a predetermined threshold) is selected. Alternatively, the base station apparatus 310 and the mobile station apparatus 320 may perform scheduling so that measurement is performed as close as possible.
Then, the correction coefficient calculation unit 25, based on the selected combination, to calculate the correction coefficient B _c. For example, the correction coefficient calculation unit 25 sets the correction coefficient b _{c, 1} = hr _{, 11} as described above, and thereafter calculates all correction coefficients using the relational expressions between the correction coefficients in order.
The correction coefficient calculator 25 holds (stores) the calculated correction coefficient _Bc in the register 26.

When correction calculation is performed in a state where the correction coefficient Bc is registered, the correction amount for the current correction coefficient is obtained, so the correction coefficient calculation unit 25 multiplies the current correction coefficient by the calculation result. The obtained value is recorded in the register as a new correction coefficient.
Similarly, the mobile station apparatus 320 calculates the correction coefficient Uc and corrects the transmission / reception characteristic difference of the transmission signal.

As described above, the correction coefficient calculation unit 25 determines the correction coefficient for matching the characteristics of the analog transmission circuit and the analog reception circuit, the transmission path characteristics measured by the transmission path measurement unit 17, and the analog transmission circuit. Based on the relational expression (for example, in the case of 2 × 2 MIMO, Expressions (21) to (24)) when the characteristics and the characteristics of the analog reception circuit are matched with each other, are represented by the expression of the transmission path characteristics. calculate.
Thereby, the correction coefficient calculation unit 25 can calculate the correction coefficient by a simple calculation based on the transmission path characteristics, as exemplified by the equations (21) to (24). Accordingly, it is possible to reduce the amount of communication and the amount of calculation required for calibration of the difference between the transmission and reception characteristics.

  In particular, the correction coefficient calculation unit 25 uses the value of the transmission path characteristic of the communication path in the antenna as the value of the correction coefficient for any of the antennas 8-1 to 8-m, as shown in Expression (21). Set. Thereby, the appearance of the indefinite coefficient c in the correction coefficient can be suppressed, and the communication amount of the parameter for calculating the correction coefficient and the calculation amount in calculating the correction coefficient can be further reduced.

  In addition, the correction coefficient calculation unit 25 redundantly calculates the correction coefficient value and takes the average of the calculated values, thereby reducing the correction coefficient variation due to the measurement error.

As described above, the base station device and the mobile station device have been described above. However, the present invention is not limited to this, and can be applied to the case of fixed communication devices or the case of a mobile communication device. is there. The present invention can be applied to various communication apparatuses that include a plurality of antennas and perform communication by time division duplex.
In the above description, a case has been described in which a transmission / reception characteristic difference is corrected (calibrated) on the transmission side. However, the correction may be performed on the reception side.

  Further, when notifying the transmission path measurement result for calculating the correction coefficient between the communication devices, the transmission path measurement result to be notified may be measured in the past. Here, unlike the time variation of the characteristics of the radio space, the time variation of the difference in characteristics in transmission and reception is considered to be relatively small. Therefore, even if the correction coefficient is obtained using the transmission line measurement results obtained in the past, a good correction coefficient can be obtained if the transmission line characteristics at sufficiently close times are obtained for each transmission line. That is, the correction coefficient that can match the transmission and reception characteristics can be obtained by obtaining the correction coefficient using the transmission path characteristics in the state where the characteristics of the radio space are similar.

  Next, a minimum configuration in the base station apparatus (communication apparatus) 310 will be described with reference to FIG. FIG. 7 is a configuration diagram illustrating a minimum configuration of the present invention in the base station apparatus 310 among the units illustrated in FIG. 6. In the figure, among the units of the base station apparatus 310 shown in FIG. 6, the antennas 8-1 to 8-m, the correction circuit 9a, the transmission / reception changeover switch 13a, the transmission path measurement unit 17, and the correction coefficient calculation unit. 25, an analog transmission circuit 33, and an analog reception circuit 34 are shown.

In this configuration, the transmission path measurement unit 17 obtains the transmission path characteristics as described above based on the configuration shown in FIG. Then, the correction coefficient calculation unit 25 sets the correction coefficient when the transmission line characteristic obtained by the transmission line measurement unit 17 is matched with the characteristic of the analog transmission circuit 33 and the characteristic of the analog reception circuit 34 as an equation of the transmission line characteristic. The correction coefficient is calculated based on the relational expression indicated by
Thereby, the correction coefficient calculation unit 25 can calculate the correction coefficient by a simple calculation based on the transmission path characteristics. Accordingly, it is possible to reduce the amount of communication and the amount of calculation required for calibration of the difference between the transmission and reception characteristics.

Note that a computer-readable program for realizing all or part of the functions of the correction circuit 9a, the digital / analog conversion circuit 11a, the analog / digital conversion circuit 12a, the register 26, and the baseband unit 321 is readable. The processing of each unit may be performed by recording on a recording medium, reading the program recorded on the recording medium into a computer system, and executing the program. Here, the “computer system” includes an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention.

8-1 to 8-m, 19-1 to 19-n Antenna 9a, 9b, 9c, 9d Correction circuit 11a, 11b, 11c, 11d Digital / analog conversion circuit 12a, 12b, 12c, 12d Analog / digital conversion circuit 13a , 13b, 13c, 13d Transmission / reception selector switch 14 Pilot signal generation unit 15 Modulation unit 16 Demodulation unit 17 Transmission path measurement unit 23, 24 Memory 25 Correction coefficient calculation unit 26 Register 27 Mapping unit 100, 200, 300 Communication systems 110, 210, 310 Base station apparatus 120, 220, 320 Mobile station apparatus 321 Baseband unit

Claims (6)

An analog transmission circuit and an analog reception circuit in each of the plurality of antennas;
A transmission / reception selector switch for switching between the analog transmission circuit and the analog reception circuit to realize communication in time division duplex;
A transmission path measurement unit for measuring transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space;
Correction coefficient for matching the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit, the transmission path characteristics measured by the transmission path measurement unit, the characteristics of the analog transmission circuit, and the characteristics of the analog reception circuit A correction coefficient calculation unit that calculates the correction coefficient based on the relational expression shown by the equation of the transmission path characteristics,
Based on the correction coefficient calculated by the correction coefficient calculation unit, a correction circuit that performs correction to match the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit;
A communication apparatus comprising:   The communication apparatus according to claim 1, wherein the correction coefficient calculation unit sets a value of a transmission path characteristic of a communication path in the antenna as a value of a correction coefficient for any one of the antennas.   The communication apparatus according to claim 1, wherein the correction coefficient calculation unit calculates the correction coefficient value redundantly and obtains the correction coefficient by taking an average of the calculated values. An analog transmission circuit and an analog reception circuit in each of the plurality of antennas;
A transmission / reception selector switch for switching between the analog transmission circuit and the analog reception circuit to realize communication in time division duplex;
A transmission path measurement unit for measuring transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space;
Correction coefficient for matching the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit, the transmission path characteristics measured by the transmission path measurement unit, the characteristics of the analog transmission circuit, and the characteristics of the analog reception circuit A correction coefficient calculation unit that calculates the correction coefficient based on the relational expression shown by the equation of the transmission path characteristics,
Based on the correction coefficient calculated by the correction coefficient calculation unit, a correction circuit that performs correction to match the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit;
A communication system comprising a plurality of communication devices including An analog transmission circuit and an analog reception circuit in each of the plurality of antennas;
A transmission / reception selector switch for switching between the analog transmission circuit and the analog reception circuit to realize communication in time division duplex;
A transmission / reception characteristic calibration method for a communication device comprising:
A transmission path measuring step for measuring transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space;
Correction coefficient for matching the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit, the transmission path characteristics measured in the transmission path measurement step, the characteristics of the analog transmission circuit, and the characteristics of the analog reception circuit And a correction coefficient calculation step for calculating the correction coefficient based on the relational expression shown by the equation of the transmission path characteristic when
Based on the correction coefficient calculated in the correction coefficient calculation step, a correction step for performing correction to match the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit;
A transmission / reception characteristic calibration method comprising: An analog transmission circuit and an analog reception circuit in each of the plurality of antennas;
A transmission / reception selector switch for switching between the analog transmission circuit and the analog reception circuit to realize communication in time division duplex;
A computer for calibrating transmission / reception characteristics of a communication device comprising:
A transmission path measuring step for measuring transmission path characteristics of each communication path including the analog transmission circuit and the analog reception circuit in addition to a wireless space;
Correction coefficient for matching the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit, the transmission path characteristics measured in the transmission path measurement step, the characteristics of the analog transmission circuit, and the characteristics of the analog reception circuit And a correction coefficient calculation step for calculating the correction coefficient based on the relational expression shown by the equation of the transmission path characteristic when
Based on the correction coefficient calculated in the correction coefficient calculation step, a correction step for performing correction to match the characteristics of the analog transmission circuit and the characteristics of the analog reception circuit;
A program for running

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