JP4447503B2 - Communication device and calibration weight estimation method - Google Patents

Description

  The present invention relates to a communication device and a calibration weight estimation method.

  Conventionally, in a base station apparatus that uses a plurality of antennas as adaptive array antennas, the transmission characteristics related to the amplitude and phase of communication signals transmitted from each antenna are equivalent to the reception characteristics related to the amplitude and phase of communication signals received by each antenna. Thus, the amplitude and phase of the communication signal to be transmitted are adjusted for each antenna. In this way, the directivity of the adaptive array antenna can be matched to the mobile station apparatus that is the transmission source of the received communication signal.

  By the way, a base station apparatus of a recent mobile communication system performs the above adjustment by digital signal processing. That is, when adjusting the amplitude and phase of a communication signal, before the D / A conversion of the communication signal to be transmitted is performed, the communication signal received by each antenna is based on the amplitude and phase after the A / D conversion. To make adjustments. For this reason, in the base station apparatus in which the antenna is separated from the base station apparatus main body including the transmission / reception unit that performs A / D conversion and D / A conversion of the communication signal, the adjustment is performed in the base station apparatus main body. Will be done. On the other hand, a power amplifier for transmitting a communication signal from an antenna and a preamplifier for amplifying a received signal are installed in the immediate vicinity of the antenna, not the base station apparatus main body. In this case, since the length of the cable connecting the antenna and the base station apparatus main body is different for each antenna, the amplitude and phase of the transmitted / received communication signal varies for each antenna, and the effect of the adjustment is impaired. May be. In general, this variation differs for each frequency of the communication signal.

  In view of such circumstances, the base station apparatus performs processing (calibration) for calibrating the amplitude and phase of the communication signal for each antenna and for each frequency channel. In this calibration, a calibration weight calculated by a predetermined calibration weight calculation process is used.

  For the calibration weight calculation process, one mobile station device as a calibration terminal is usually installed in the base station device. The input / output of the antenna of the calibration terminal is electrically coupled to each antenna of the base station apparatus by a coupler. For this reason, the calibration terminal receives the signal output from the coupler (that is, the downlink communication signal transmitted from the antenna), and causes the base station apparatus to receive the signal generated by itself as an uplink communication signal through each coupler. Can do.

  In the following description, the calibration terminal is a part that is installed integrally with the antenna away from the calibration unit, the antenna, and the base station main unit (usually including an amplifier circuit such as the power amplifier or preamplifier). Part. The antenna unit includes the plurality of antennas, and each antenna is connected to a transmission / reception unit and a calibration unit.

  First, regarding the uplink signal, the test signal (calibration signal) generated in the calibration unit is received as a communication signal by the transmission / reception unit via the antenna unit. The transmission / reception unit acquires the difference in amplitude and phase between the test signals received via each antenna unit.

  Next, for the downlink signal, a test signal (calibration signal) is generated in the transmission / reception unit, and is received as a communication signal by the calibration unit via each antenna included in the antenna unit. Each antenna is installed to transmit and receive the same signal, and the calibration unit synthesizes the signals output from the respective antenna units as a communication signal to obtain a reception signal. On the other hand, in the calibration weight calculation process, since it is necessary to acquire the difference in amplitude and phase between signals received via each antenna, the transmission / reception unit transmits the test signal via only one antenna at a time. This is done for each antenna. The calibration unit acquires the difference in amplitude and phase between the test signals received via each antenna.

In the calibration weight calculation process, the calibration amount (calibration weight) for each antenna is calculated based on the amplitude and phase difference between the test signals obtained during reception and transmission. In the calibration, the amplitude and phase of the communication signal to be transmitted are calibrated based on the calibration weight calculated in this way. Note that the calibration weight calculation process is performed for each frequency channel. Patent Document 1 describes one example of such calibration.
JP 2001-53661 A

  By the way, in the conventional calibration weight calculation process, it is necessary to redo the calibration weight calculation process when the temperature (environment temperature) fluctuates in the surrounding environment of the base station apparatus. Since the electrical characteristics of the electronic components used in the transmission / reception circuit and amplification circuit provided in the base station device have temperature characteristics, when the environmental temperature changes, the amplitude and phase of the communication signals transmitted and received by each antenna are Change occurs. As a result, the phase and amplitude relationship between the antennas changes.

  Thus, conventionally, it has been necessary to redo the calibration weight calculation process triggered by a change in environmental temperature. However, in the calibration weight calculation process, since the test signal is transmitted or received using the communication channel used for the communication signal, the communication signal is transmitted / received during the test in the communication channel used for transmitting / receiving the test signal. It is not possible. For this reason, every time the calibration weight calculation process is performed again, there is a time during which communication channels included in each frequency channel cannot be used for communication.

  The present invention has been made in view of the above problems, and one of its purposes is to perform communication included in the frequency channel for at least some of the frequency channels when performing the calibration weight calculation process again. An object of the present invention is to provide a communication apparatus and a calibration weight estimation method capable of reducing a time during which a channel cannot be used for communication.

  A communication apparatus according to the present invention for solving the above-described problems detects that a predetermined condition is satisfied in a communication apparatus including communication means for performing communication using at least one of a plurality of frequency channels. And a communication unit configured to perform a predetermined calibration weight calculation process for at least one of the plurality of frequency channels when the detection unit and the detection unit detect that the predetermined condition is satisfied. Calibration weight calculation processing control means for controlling the calibration weight, and calibration weight for each of at least one frequency channel calculated by the predetermined calibration weight calculation processing performed by the control of the calibration weight calculation processing control means, , The predetermined means by the detection means A calibration weight for each of the at least one frequency channel calculated by the predetermined calibration weight calculation process before it is detected that the predetermined condition is satisfied, and that the predetermined condition is satisfied by the detection means Based on the calibration weight for the frequency channel other than the at least one frequency channel calculated by the predetermined calibration weight calculation process before being detected, the frequency channel for the frequency channel other than the at least one frequency channel is determined. Calibration weight estimating means for estimating a calibration weight.

According to the present invention, the calibration weight for each of at least some of the frequency channels can be estimated without actually performing the calibration weight calculation process for the frequency channel. When the calibration is performed again because the condition is satisfied, the time during which communication channels included in these frequency channels cannot be used for communication can be reduced .

Also, calibration weight estimating method according to the present invention, at least one of the amplitude or phase of the communication signal transmitted in a communications device comprising communicating means for communicating using at least one of a plurality of frequency channels A calibration weight estimation method for estimating a calibration weight for calibrating a detection method, wherein a detection step for detecting that a predetermined condition is satisfied is detected, and that the predetermined condition is detected in the detection step to the one of the plurality of frequency channels, to perform at least one calibration weight calculation process of the Jo Tokoro about the frequency channel, and calibration weight calculation processing control step of controlling the communication device, said calibration weight calculation process Done in control step A calibration weight for each of at least one frequency channel calculated by the predetermined calibration weight calculation process, and the predetermined calibration weight calculation before the detection step detects that the predetermined condition is satisfied. A calibration weight for each of the at least one frequency channel calculated by the processing, and the calibration weight calculated by the predetermined calibration weight calculation processing before detecting that the predetermined condition is satisfied in the detection step. A calibration weight for a frequency channel other than the at least one frequency channel, and a calibration weight for a frequency channel other than the at least one frequency channel. Characterized in that it comprises a calibration weight estimation step of, the.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a mobile communication system 1 according to the present embodiment. As shown in FIG. 1, the mobile communication system 1 includes a base station device 2, a mobile station device 3, and a communication network 4. In the mobile communication system 1, the base station device 2 and the mobile station device 3 communicate with each other wirelessly. The mobile station device 3 communicates with the communication network 4 via the base station device 2.

  As illustrated in FIG. 2, the base station device 2 includes a control unit 10, a storage unit 20, a network interface unit 30, a wireless communication unit 40, and a calibration unit 50.

  The control unit 10 includes a processing unit for executing a program stored in the storage unit 20, controls each unit of the base station apparatus 2, and executes processing related to a call and data communication.

  The storage unit 20 operates as a work memory of the control unit 10. The storage unit 20 holds programs and parameters related to various processes performed by the control unit 10.

  The network interface unit 30 is connected to the communication network 4 and receives an audio signal, a communication packet, and the like from the communication network 4 and outputs them to the control unit 10 or according to an instruction from the control unit 10. A packet or the like is transmitted to the communication network 4.

  The wireless communication unit 40 includes a plurality of antennas, and receives and demodulates a voice signal, a communication packet, and the like from the mobile station device 3 with each antenna, and outputs them to the control unit 10. Further, in accordance with an instruction input from the control unit 10, the audio signal or communication packet input from the control unit 10 is modulated and transmitted to the radio section via each antenna.

  Note that the wireless communication unit 40 performs communication using a space division multiple access (SDMA) by using the plurality of antennas as an adaptive array antenna. The space division multiplexing method is a method of adjusting the antenna directivity to the position where the mobile station device 3 exists by adjusting at least one of the amplitude or phase of communication signals transmitted from a plurality of antennas. In the space division multiplexing method, the same signal is transmitted and received by a plurality of antennas.

  Moreover, the radio | wireless communication part 40 communicates using the several radio | wireless carrier from which a frequency mutually differs by a frequency division multiplex system (FDMA, Frequency Division Multiple Access). Each radio carrier constitutes a frequency channel, and different signals are transmitted and received in each frequency channel.

  The calibration unit 50 is a mobile station device 3 customized for performing a calibration weight calculation process. The calibration weight calculation process is a process for calculating a calibration weight that is used to reflect the power loss and delay that occur during signal transmission in the base station apparatus 2 in the amplitude and phase of the transmission signal. The calibration weight calculation process will be described in detail later.

  The mobile station apparatus 3 communicates with the base station apparatus 2 by receiving a signal wirelessly transmitted from the base station apparatus 2 and wirelessly transmitting the signal to the base station apparatus 2. Examples of the mobile station device 3 include a mobile phone terminal, a PHS terminal, and a wireless LAN terminal.

  In addition, in the communication performed between the base station apparatus 2 and the mobile station apparatus 3, the space division multiplexing method and the frequency division multiplexing method are used, and the time division duplex method (TDD, Time Division Duplex) is used. The In this time division duplex method, the same frequency channel transmits a signal (uplink signal) transmitted from the mobile station apparatus 3 to the base station apparatus 2 and a signal (downlink signal) transmitted from the base station apparatus 2 to the mobile station apparatus 3. ) And is used while being switched in time division.

  The communication network 4 is connected to a plurality of computers (not shown), and relays communication between each computer and the base station apparatus 2. Specifically, it may be an exchange network of a mobile communication system or a TCP / IP network.

  FIG. 3 is a functional block and hardware configuration diagram of the base station apparatus 2 according to the present embodiment. As shown in the figure, the base station device 2 physically includes a base station device main body 100, an antenna unit 101, and a cable connecting them.

  The base station apparatus main body 100 and the antenna unit 101 are spaced apart from each other. Specifically, the antenna unit 101 is arranged at the top of the steel tower, and the base station device main body 100 is arranged at the base of the steel tower. Thus, since the base station apparatus main body 100 and the antenna part 101 are separated from each other, in signal transmission / reception in the base station apparatus 2, power loss and delay occur during internal signal transmission. These power loss and delay are different for each antenna because the length of the cable connecting the antenna unit 101 and the base station apparatus main body 100 and the circuit through which the signal passes are different for each antenna. Moreover, these power loss and delay differ also for every frequency, and are the quantity which changes also with changes of surrounding environment, such as temperature.

  By the way, the base station apparatus 2 employs the space division multiplexing system as described above. For this reason, the base station apparatus 2 calculates a reception weight indicating an amount of difference between the antennas of the amplitude or phase of the received communication signal based on the amplitude or phase of the received communication signal. This calculation process is performed for each mobile station apparatus 3.

  Then, the transmission weight is calculated so as to match the directivity to the mobile station apparatus 3 estimated based on the reception weight. This calculation process is also performed for each mobile station apparatus 3. Then, by multiplying the communication signal for each antenna by the calculated transmission weight, at least one of the amplitude or phase of the communication signal is adjusted, and the directivity of the transmitted radio wave is matched to the mobile station apparatus 3.

  However, as described above, when signals are transmitted inside the base station apparatus 2, there are circuit elements that differ for each antenna, such as circuits and cables through which signals pass, and this causes different power loss and delay for each antenna. If the transmission weight is calculated based only on the reception weight, the directivity may not be suitable for the mobile station device 3 due to these power loss and delay. Therefore, in this embodiment, by transmitting and receiving a known calibration signal as a communication signal, a calibration weight calculation process for measuring these power loss and delay in advance is performed, and a calibration weight indicating the measurement result is obtained. This is reflected in the transmission weight. That is, when a communication signal is transmitted, a predetermined calibration process (calibration) relating to the amplitude or phase of the communication signal is performed based on the calibration weight.

  As described above, the power loss and delay differ for each antenna, for each frequency, and for each temperature. Therefore, in the calibration weight calculation process, it is necessary to measure under each measurement condition. However, if each one is performed separately, it takes time and communication signals cannot be transmitted during that time. Therefore, in this embodiment, the calibration weight calculation process is performed for a certain frequency channel, and the result is It can be applied to other frequency channels.

  The configuration and operation of the base station apparatus 2 according to the present embodiment for realizing the calibration weight calculation process will be described in detail below. As shown in FIG. 3, the base station apparatus 2 configures an antenna i section 81-i (i = 1 to n, n is the number of antennas) constituting the antenna section 80 and a base station apparatus main body section 70. The control unit 10, the base station transmission / reception unit 60, the calibration unit 50, and the cables 80-i (i = 1 to n) and the cables 88-i (i = 1 to n) for connecting them are included. It is configured.

  The control unit 10 includes a calibration weight calculation processing control unit 11 and a calibration weight calculation unit 12.

  The antenna i section 81-i includes an antenna 82-i, a coupler (coupler) 83-i, a T (Transfer) / R (Receive) switch 84-i, a power amplifier (power amplifier) 85-i, The T / R switch 86-i and a low noise amplifier (low noise amplifier) 87-i are included.

The base station transmission / reception unit 60 includes a T / R switch 61-i (i = 1 to n), an RF / IF unit 62-i (i = 1 to n), and an RF / IF unit 63-i (i = 1). N) and a carrier p transceiver unit 64-p (p = 1 to m). However, m is the number of frequency channels, each carrier p transceiver 64-p are provided to perform communications using a frequency channel of a frequency f _p.

  The calibration unit 50 includes a synthesis / distribution unit 51, a T / R switch 52, an RF / IF unit 53, a transmission unit 54, an RF / IF unit 56, and a reception unit 57. Yes.

  First, the outline of the calibration weight calculation process in the present embodiment will be described with reference to FIG. In the present embodiment, the calibration weight calculation processing control unit 11 detects that a predetermined condition is satisfied. When it is detected that the predetermined condition is satisfied, the calibration weight calculation process control unit 11 controls the base station apparatus 2 so as to execute the calibration weight calculation process. As this predetermined condition, for example, the power loss at the time of signal transmission in the base station device 2 such as the environmental temperature of the base station device 2 (more specifically, the ambient temperature, for example) has changed. An event in which the amount of delay changes may occur, or when the calibration weight calculation process is performed periodically, the elapsed time from the previous calibration may be a predetermined time. For this processing, it is desirable that the base station apparatus 2 includes a thermometer and a clock (not shown).

  In the calibration weight calculation process started in this way, the base station apparatus 2 calculates the calibration weight basic amount for each of the upstream signal and the downstream signal, and both the calibration weight basic amount for the upstream signal and the downstream signal. Based on the above, a calibration weight is calculated.

  First, the uplink signal will be described. In the upstream calibration, the calibration unit 50 generates a known calibration signal. At this time, a calibration signal may be generated by selecting a calibration signal stored in the storage unit 20. Note that a tone signal (sine wave signal) or a burst signal (bit string) can be used as the calibration signal, but here, a description will be given assuming that a tone signal is used.

And the calibration part 50 transmits the produced | generated calibration signal with respect to the base station transmission / reception part 60 via each antenna i part 81-i. The control unit 10, the time transmitted by the calibration frequency of the signal frequency f _{p (p} = 1~m, m is the number of frequency channels) to be the one of controls the calibration unit 50 Yes.

Carrier p transceiver 64-p of the base station transceiver unit 60 acquires the calibration signal of a frequency f _p received, and a known calibration signal, the phase and the amount of difference amplitude. Then, based on the acquired difference amount, the basic weight of the calibration weight of the uplink signal is calculated for each antenna i unit 81-i.

Next, the downlink signal will be described. The downlink calibration carrier p transceiver 64-p selected by the determination of the control unit 10 generates a known calibration signal frequency f _p, through each antenna i unit 81-i, calibration It transmits to the part 50. Also at this time, a calibration signal may be generated by selecting a calibration signal stored in the storage unit 20. Also, a tone signal (sine wave signal) or a burst signal (bit string) can be used for this calibration signal. Here, the description will be made assuming that a tone signal is used.

The calibration unit 50 acquires the calibration signal of a frequency f _p received, and a known calibration signal, the phase and the amount of difference amplitude. Then, based on the acquired difference amount, a calibration weight basic amount of the downlink signal is calculated for each antenna i unit 81-i.

  Since the calibration unit 50 is the mobile station device 3 as described above, it can receive only one signal at a time. For this reason, the calibration unit 50 receives the signals output from the antenna i units 81-i after being combined by the combining / distributing unit 51. For this reason, in order to calculate the calibration weight basic amount for each antenna i unit 81-i in the calibration weight basic amount calculation processing of the downlink signal, the carrier p transmission / reception unit 64-p is configured for each antenna i unit 81-i. The calibration signal is transmitted sequentially.

  Further, the calibration unit 50 receives calibration signals of different frequencies by the carrier p transmission / reception unit 64-p that transmits the calibration signal. For this purpose, the calibration unit 50 is configured to switch the frequency of the received signal.

  The calibration weight calculation unit 12 calculates the calibration weight based on both the upstream signal and the downstream signal calibration weight basic amount calculated as described above. In this embodiment, calibration weights calculated in the past are stored, and calibration weights of frequency channels other than the specific frequency channel are estimated based on the calibration weights of the specific frequency channel calculated this time. Do.

  Hereinafter, a specific calibration weight calculation process in the base station apparatus 2 will be described in more detail with reference to FIGS. 3 and 4.

  First, the calibration weight calculation process control unit 11 among the units included in the control unit 10 will be described.

  The calibration weight calculation process control unit 11 instructs execution of the calibration weight calculation process when a predetermined condition is detected. Examples of this predetermined condition are as described above.

  The calibration weight calculation processing control unit 11 determines the frequency of the calibration signal. Then, the base station transceiver unit 60 and the calibration unit 50 are instructed to transmit and receive the calibration signal at the determined frequency.

  Next, the antenna i part 81-i will be described. The antenna i unit 81-i acquires a radio wave arriving at the antenna 82-i, inputs a signal included in the radio wave to the base station transceiver unit 60, and a signal output from the base station transceiver unit 60. Is transmitted from the antenna 82-i to the wireless section. Usually, radio waves are transmitted to and received from the mobile station apparatus 3.

  The antenna i unit 81-i also performs amplification processing of signals included in radio waves arriving at the antenna 82-i and amplification processing of signals output from the base station transmission / reception unit 60. Specifically, in this embodiment, the time division duplex method is used as described above, and the time slots of the upstream signal and the downstream signal are set by the T / R switch 84-i and the T / R switch 86-i. Each route is assigned to a different route, and communication is performed via an amplifier installed in each route. In the case of an upstream signal, the power is transmitted to the signal by the power amplifier 85-i to control the transmission power when transmitting the signal from the antenna 82-i. In the case of a downstream signal, the low noise amplifier 87-i performs amplification with a very low noise level to amplify the received power of the signal without increasing the noise level of the received signal as much as possible. The coupler 83-i will be described later.

  Further, as described above, the antenna i unit 81-i is installed at the tip of the steel tower where the base station device 2 is installed. One base station transmission / reception unit 60 is installed in a portion close to the ground of the steel tower. Therefore, there is often a distance of 10 m or more between the T / R switch 86-i and the T / R switch 61-i, and the cable 80-i is connected between them.

  Next, the base station transmission / reception unit 60 will be described. The base station transmission / reception unit 60 performs a demodulation / decoding process for demodulating and decoding a signal output from the antenna i unit 81-i and a modulation / coding process for modulating and encoding a signal output to the antenna i unit 81-i. Do. Further, although not shown in the figure, signals are also transmitted / received to / from the network interface unit 30 via the control unit 10, and communication between the communication network 4 and the mobile station device 3 is relayed. The control unit 10 and the base station transmission / reception unit 60 are communicably connected via a bus 90.

  T / R switch 61-i is connected to cable 80-i and includes a time slot including a signal output from antenna i unit 81-i, a time slot including a signal output to antenna i unit 81-i, Switch the route with. Thus, the signal output from the antenna i unit 81-i is output to the RF / IF unit 63-i, and the signal output from the RF / IF unit 62-i is transmitted to the cable 80-i. is doing. The T / R switch 61-i, the RF / IF unit 62-i, and the RF / IF unit 63-i are provided corresponding to the antenna i unit 81-i, and are connected to the antenna i unit 81-i. To input / output signals.

  The RF / IF unit 63-i performs a frequency conversion process for converting a signal output from the corresponding antenna i unit 81-i from a radio frequency to a baseband frequency, and converts the signal into a frequency channel of the radio frequency. It outputs to the carrier p transmission / reception part 64-p provided in order to perform communication using. Conversely, the RF / IF unit 62-i converts the signal output from each carrier p transceiver unit 64-p from a baseband frequency to a radio frequency corresponding to each carrier p transceiver unit 64-p. Processing is performed and the signal is transmitted to the corresponding antenna i section 81-i.

  FIG. 4 is a diagram illustrating functional blocks included in the carrier p transceiver unit 64-p. As shown in the figure, the carrier p transmission / reception unit 64-p includes a transmission unit 66-p and a reception unit 71-p.

  The reception unit 71-p includes a detection unit 72-p and a first calibration weight basic amount calculation unit 73-p.

The detector 72-p performs a detection process on the signal input from each RF / IF unit 63-i. Specifically, DFT (Discrete Fourier Transpose, discrete Fourier transform) by a bandpass filter (not shown) to the signal by performing processing to take out only a component of a specific frequency f _p. Then, demodulation and decoding processing is performed on the signal having the specific frequency f _p , the signal transmitted from the mobile station device 3 is acquired as a bit string, and is output to the control unit 10. In addition, the phase and amplitude of the signal input from each RF / IF unit 63-i are acquired and output to the first calibration weight basic amount calculation unit 73-p and the transmission unit 66-p.

  The first calibration weight basic amount calculation unit 73-p acquires the phase and amplitude of the calibration signal transmitted from the calibration unit 50 among the signals detected by the detection unit 72-p, and calibrates the upstream signal. Calculate the basic weight. The first calibration weight basic amount calculation unit 73-p outputs the calculated calibration weight basic amount of the upstream signal to the control unit 10.

  The calibration signal received by the base station transmission / reception unit 60 is a known signal transmitted. However, when the signal is transmitted inside the base station device 2, the calibration signal is subjected to power loss or delay, and its amplitude and phase are reduced. It has changed. The first calibration weight basic amount calculation unit 73-p calculates the calibration weight basic amount of the upstream signal based on the phase rotation amount and the amplitude change amount.

  Next, the transmission unit 66-p will be described. FIG. 4 is a diagram illustrating functional blocks of the transmission unit 66-p. As shown in the figure, the transmission unit 66-p includes an antenna weight multiplication unit 67-p, a transmission signal generation unit 69-p, and a weight calculation unit 70-p.

  The transmission signal generation unit 69-p acquires the bit string output from the network interface unit 30 via the control unit 10. Then, in order to send the acquired signal to the radio section, the signal is encoded and modulated to generate a transmission signal. Then, predetermined encoding / modulation processing is performed on the generated signal, and the resultant signal is output to the antenna weight multiplication unit 67-p.

The transmission signal generating unit 69-p is due to the calibration weight calculation control unit 11 receives an instruction for reception of the calibration signal at a frequency f _p that is assigned to the carrier p transceiver 64-p . When this instruction is received, a known calibration signal is generated. The transmission signal generation unit 69-p also performs a predetermined encoding / modulation process on the calibration signal and outputs it to the antenna weight multiplication unit 67-p.

  When the communication signal is transmitted, the weight calculation unit 70-p is based on the phase and amplitude of the received signal received by each antenna i unit 81-i output from the detection unit 72-p. Calculate the transmission weight. Further, the calculated transmission weight is corrected based on the calibration weight input from the control unit 10. On the other hand, when transmitting the calibration signal, the transmission weight is calculated so that the amplitude and phase of the calibration signal transmitted from each antenna i unit 81-i are equal. The weight calculation unit 70-p outputs the transmission weight corrected or calculated in this way to the antenna weight multiplication unit 67-p.

  The antenna weight multiplication unit 67-p multiplies the transmission signal output from the transmission signal generation unit 69-p by the transmission weight and outputs the result to each RF / IF unit 62-i.

  Next, the calibration unit 50 will be described. First, the part related to the upstream calibration weight calculation process will be described. The transmission unit 54 includes a transmission signal generation unit 55. The transmission signal generation unit 55 generates a known calibration signal. Then, encoding / modulation processing corresponding to the type of calibration signal is performed, and the result is output to the RF / IF unit 53.

  The RF / IF unit 53 converts the calibration signal from the baseband frequency to the radio frequency, and outputs it to the T / R switch 52. The T / R switch 52 switches the route between the time slot including the signal output from the combining / distributing unit 51 and the time slot including the signal output to the combining / distributing unit 51, thereby switching the path from the combining / distributing unit 51. The output signal is output to the RF / IF unit 56, and the signal output from the RF / IF unit 53 is sent to the synthesis / distribution unit 51.

  The combining / distributing unit 51 is connected to the cable 88-n, and distributes and transmits the calibration signal output from the T / R switch 52 to the coupler 83-i of each antenna i unit 81-i.

  The coupler 83-i electrically connects a communication line installed between the T / R switch 84-i and the antenna 82-i and the cable 88-i. That is, by the coupler 83-i, the signal flowing through the communication line installed between the T / R switch 84-i and the antenna 82-i also flows into the cable 88-i, and conversely to the cable 88-i. The flowing signal also flows through a communication line installed between the T / R switch 84-i and the antenna 82-i. For this reason, for example, a signal flowing from the T / R switch 84-i to the antenna 82-i is acquired by the coupler 83-i and then flows to the cable 88-i, so that it can be acquired by the combining / distributing unit 51. Become. Further, a signal sent from the combining / distributing unit 51 to the cable 88-i is also acquired by the coupler 83-i and sent to a communication line installed between the T / R switch 84-i and the antenna 82-i. Therefore, it can be acquired by the T / R switch 84-i.

  In this way, the T / R switch 84-i included in the antenna i unit 81-i acquires the calibration signal distributed and transmitted by the combining / distributing unit 51. The calibration signal is transmitted by adjusting the time in the calibration unit 50 so as to enter the time slot used for the time division duplex uplink signal. For this purpose, it is desirable to synchronize each part using a clock (not shown).

  Next, a part related to the downstream calibration weight calculation process will be described. The synthesizer / distributor 51 outputs the calibration signal to the T / R switch 52 when receiving the calibration signal generated by the transmission signal generator 69-p. The T / R switch 52 outputs the calibration signal to the RF / IF unit 56. The RF / IF unit 56 performs frequency conversion processing for converting the input calibration signal from a radio frequency to a baseband frequency. Then, the calibration signal subjected to frequency conversion processing is output to the receiving unit 57.

  The reception unit 57 includes a detection unit 58 and a second calibration weight basic amount calculation unit 59. The detector 58 detects the calibration signal output from the RF / IF unit 56. In the detection, the original calibration signal is acquired by performing DFT processing on the calibration signal output from the RF / IF unit 56.

  As described above, the calibration unit 50 is configured to be able to switch the frequency of the received signal. Specifically, in the detection processing in the detection unit 58, only the component of the specific frequency determined and instructed by the calibration weight calculation processing control unit 11 is extracted. That is, the frequency extracted here is the frequency of the calibration signal transmitted from the base station transceiver unit 60.

  The calibration signal received by the calibration unit 50 is a known signal transmitted. However, the amplitude and phase change due to power loss and delay during signal transmission in the base station apparatus 2. is doing. The second calibration weight basic amount calculation unit 59 calculates the calibration weight basic amount of the downstream signal based on the phase rotation amount and the amplitude change amount. The downlink signal calibration weight basic amount calculated in this way is output to the control unit 10.

Next, the calibration weight calculation unit 12 among the units included in the control unit 10 will be described. The calibration weight calculation unit 12 includes the calibration weight basic amount of the upstream signal output from the first calibration weight basic amount calculation unit 73-p and the downstream signal output from the second calibration weight basic amount calculation unit 59. a calibration weight basic amount of, calculates the calibration weight on frequency channel f _p based on. Then, the calculated calibration weight is output to the weight calculation unit 70-p.

  Further, the calibration weight calculation unit 12 stores the calibration weight for each frequency channel calculated in the calibration weight calculation process performed previously in the calibration weight table of the storage unit 20. FIG. 5 is a specific example of this. As shown in the figure, the calibration weight table stores the calibration weight for each antenna i section 81-i for each frequency channel. A vector whose element is a calibration weight for each antenna i section 81-i stored for each frequency channel is also called a calibration vector.

In the present embodiment, the calibration weight calculation process is performed on the frequency channel determined by the calibration weight calculation process control unit 11. For this reason, the calibration weight calculation process is not necessarily performed in all frequency channels. When calibration weight calculation process only on the frequency channel of a frequency f _p is performed, the calibration weight calculator 12 includes a calibration weight for the frequency channel f _p calculated in this calibration weight calculation process, the calibration Based on the calibration weight stored in the weight table, the calibration weight is also estimated for the frequency channel that has not been subjected to the calibration weight calculation process this time.

Specifically, the calibration weight calculator 12 includes a calibration weight which is calculated in the present calibration weight calculation processing for the frequency channel f _p, is calculated in the calibration weight calculation process earlier for the frequency channel f _p and a calibration weight, and calibration weight that have been calculated in the calibration weight calculation process earlier for each of the frequency channels other than the frequency channel f _p, based on the calibration weight of frequency channels other than the frequency channel f _p Is estimated.

One more specific example, the calibration weight calculator 12, for calibration weight calculated in this calibration weight calculation processing for the frequency channel f _p, calculated in the previous calibration weight calculation process a calibration weight change amount from the calibration weight (for the frequency channel f _p calculated in this calibration weight calculation process which is a calibration weight which has been calculated in a previous calibration weight calculation process, the a difference amount), and the calibration weight which has been calculated in the calibration weight calculation process earlier for each of the frequency channels other than the frequency channel f _p, based on the frequency Calibration weight of frequency channels other than Yaneru f _p may be estimated.

As another example, the calibration weight calculator 12 includes a calibration weight for the frequency channel f _p which has been calculated in a previous calibration weight calculation processing for each frequency channel other than the frequency channel f _p a calibration weight which has been calculated in a previous calibration weight calculation process, and the difference amount, a calibration weight which is calculated in the present calibration weight calculation processing for the frequency channel f _p, on the basis of the frequency channel f Calibration weights for frequency channels other than _p may be estimated.

  The calibration weight calculation unit 12 also outputs the calibration weight estimated in this way to the corresponding weight calculation unit 70-p.

  The weight calculation unit 70-p corrects the transmission weight calculated by a separate process related to the space division multiplexing method based on the calibration weight input from the calibration weight calculation unit 12. Then, the corrected transmission weight is output to the antenna weight multiplication unit 67-p. The antenna weight multiplication unit 67-p multiplies the transmission signal output from the transmission signal generation unit 69-p by the transmission weight output from the weight calculation unit 70-p, and outputs the result to each RF / IF unit 62-i. To do.

  As described above, the base station apparatus 2 performs the calibration weight calculation process to calculate and estimate the calibration weight. Then, it is possible to calibrate at least one of the amplitude and phase of the communication signal with the transmission weight corrected based on the calibration weight obtained as a result.

  Hereinafter, the process related to the calibration weight calculation and estimation will be described more specifically while presenting a specific example of the calibration signal.

The calibration signal generated in the transmission signal generation unit 55 is C _p (t), the signal output from the RF / IF unit 63-i is C ′ _ip (t), the power loss and phase rotation in the calibration unit 50 B _p and β _p , power loss and phase rotation in the cable 88-i respectively D _ip and δ _ip , and power loss and phase rotation in the antenna p transmission / reception unit 64-p from the antenna i unit 81-i, respectively E _ip and epsilon _ip, a calibration weight basic amount of an uplink signal, the antenna i unit 81-i and the one corresponding to the frequency _{f p Er (i, p)} , when a noise and _{N 1ip,} C _'ip (t) and Er (i, p) are represented by the following formulas (1) and (2), respectively. E [] is a function that takes an average value, * is a complex conjugate, i is an integer between 1 and n, and p is an integer between 1 and m. The amplitude of C _p (t) is 1. J is an imaginary unit.
C ′ _ip (t) = C _p (t) × B _p exp (jβ _p ) × D _ip exp (jδ _ip ) × E _ip exp (jε _ip ) + N _1ip (1)
Er (i, p) = E [C 'ip (t)] × C p (t) * = B p D ip E ip exp (j (β p + δ ip + ε ip)) ··· (2)

Similarly, the calibration signal generated in the transmission signal generation unit 69-j is C _j (t), the signal output from the detection unit 58 is C ′ _ip (t), and the carrier p transmission / reception unit 64-p is connected to the antenna i. The power loss and phase rotation in the unit 81-i are respectively F _ip and ζ _ip , the power loss and phase rotation in the cable 88-i are respectively G _ip and η _ip , and the power loss and phase rotation in the calibration unit 50 are respectively H _p and κ _p , and the downstream signal calibration weight basic quantities, which correspond to the antenna i section 81-i and the frequency f _p , are Et (i, p), and the noise is N _2ip , C ′ _ip (t) and Et (i, p) are represented by the following equations (3) and (4), respectively. Note that the amplitude of C _p (t) is 1.
C ′ _ip (t) = C _p (t) × F _ip exp (jζ _ip ) × G _ip exp (jη _ip ) × H _p exp (jκ _p ) + N _2ip (3)
Et (i, p) = E [C ′ _ip (t)] × C _p (t) ^* = F _ip G _ip H _p exp (j (ζ _ip + η _ip + κ _p )) (4)

In this way, the first calculated in calibration weight basic amount calculating unit 73-j and the second calibration weight basic amount calculation unit 59, calibration weight basic amount Er (i uplink signal for each frequency f _p, Both the p) and the calibration weight basic amount Et (i, p) of the downstream signal are output to the calibration weight calculation unit 12.

Calibration weight calculation unit 12, for each frequency f _p, based on the calibration weight basic amount of uplink and downlink input is calculated by the equation (5) the calibration weight w _{Cip.
w Cip = Er (i, p} ) / Et (i, p) = (B p D ip E ip) / (F ip G ip H p) exp (j (β p + δ ip + ε ip -ζ ip -η ip −κ _p )) (5)

Calibration weight calculation unit 12, and outputs this manner the calibration weight w _Cip calculated by the weight calculating unit 70-p, in association with the frequency f _p in the storage unit 20.

In the following description, it is assumed that the calibration weight for the frequency f ₁ is calculated this time and the calibration weight w _Ci2 for the frequency f ₂ is estimated. Calibration weight calculation unit 12, based on the calibration weight _{w C1p} currently calculated for the frequency _{f 1,} a calibration weight which stores (and _{w Cip-memory} for the frequency _{f p),} in the frequency _{f 2} A calibration weight w _Ci2 for is estimated by equation (6).
w _Ci2 = w _Ci2-memory × w _Ci1 / w _Ci1-memory (6)

w _Ci1 / w _Ci1-memory indicates the amount of change from the stored calibration weight w _Ci1-memory for the currently calculated calibration weight w _Ci1 . In other words, w _{Ci2 -memory} / w _{Ci1 -memory} indicates the amount of difference between the stored calibration weight w _{Ci2 -memory} and the stored calibration weight w _{Ci1 -memory} .

The process of equation (6) in the calibration weight calculation unit 12 can be performed more efficiently. That is, it can be calculated using the calibration vector described above. Specifically, first, calibration vectors C _p and C _p-memory as shown in Expression (7) are defined.
C _p = [w _C1p , w _C2p ,..., W _Cnp ] (7)
C _p-memory = [w _C1p-memory , w _C2p-memory ,..., W _Cnp-memory ] (8)

Then, a calibration weight change amount vector D is defined as shown in (9). Here, the frequency f ₁ is defined as an example.
_{D = C 1 / C 1-} memory = [w C11 / w C11-memory, w C21 / w C21-memory, ···, w Cn1 / w Cn1-memory] ··· (9)

Here, this variation vector D is regarded as an amount that does not depend on the frequency. Then, the calibration vector C _p for each frequency f _p can be calculated as shown in Expression (10).
_{C p = C p-memory ×} D = [w C1p × w C11 / w C11-memory, w C2p × w C21 / w C21-memory, ···, w Cnp × w Cn1 / w Cn1-memory] ··・ (10)

Based on the calibration weight w _Cip calculated or estimated as described above, the weight calculation unit 70-p calculates the transmission weight w _Tip of the communication signal to be transmitted by the equation (11). Note that w _Ri is a transmission weight calculated in the space division multiplexing method. This transmission weight does not depend on the frequency. The weight calculation unit 70-p corrects w _Ri by w _Cip as shown in equation (11).
w _Tip = w _Ri x w _Cip (11)

Then, the weight calculation unit 70-p outputs the transmission weight w _Tip calculated by the equation (11) to the antenna weight multiplication unit 67-p. The antenna weight multiplication unit 67-p controls the phase and amplitude of the transmission signal S (t) based on the input transmission weight w _Tip , and transmits the transmission signal having the frequency f _p transmitted from the antenna i unit 81-i. Obtain S _ip (t). Specifically, the following equation (12) is calculated.
S _ip (t) = S (t) × w _Tip (12)

  As described above, the base station apparatus 2 calculates or estimates the calibration weight and reflects it in the transmission weight of the transmission signal. That is, the transmission signal is calibrated with the calibration weight.

  Next, the calibration weight calculation process in the base station apparatus 2 will be described with reference to a process flowchart.

FIG. 6 is a flowchart of the calibration weight calculation process in the base station apparatus 2. As shown in the figure, first, each unit of the base station apparatus 2 waits for a calibration execution request from the control unit 10 (S100). When the control unit 10 issues a calibration execution request using the p-th carrier (frequency f _p ) as the selected carrier (S102), the control unit 10 waits until the communication using the frequency channel corresponding to the p-th carrier is completed. Then, a radio resource for the calibration weight calculation process is secured (S103). If secured, a calibration weight calculation process is executed (S104).

  The k-th carrier (k = 1 to m, k ≠ p) based on the calibration vector obtained by the executed calibration weight calculation process and the change amount of the calibration vector stored in the calibration weight table. The calibration vector is calculated (S105). Then, the operation calibration vector is updated with the calculated calibration vector. That is, the calculated calibration vector is used to calculate the transmission weight of the transmission signal (S106). In other words, the communication signal is calibrated by the calibration weight.

  Through the processing described above, base station apparatus 2 in the present embodiment performs calibration weight calculation processing.

  According to the present invention, the calibration weight for each of at least some of the frequency channels can be estimated without actually performing the calibration weight calculation process for the frequency channel. When the calibration is performed again because the condition is satisfied, the time during which communication channels included in these frequency channels cannot be used for communication can be reduced. In addition, the calibration weight of another frequency channel can be estimated based on the amount of change in the calibration weight for one frequency channel.

1 is a system configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a system configuration | structure figure of the base station apparatus which concerns on embodiment of this invention. It is a figure which shows the functional block and hardware constitutions of the base station apparatus which concern on embodiment of this invention. It is a figure which shows the functional block and hardware constitutions of the base station apparatus which concern on embodiment of this invention. It is a figure which shows the calibration weight storage table which concerns on embodiment of this invention. It is a figure which shows the flow of the process which concerns on embodiment of this invention.

  DESCRIPTION OF SYMBOLS 1 Mobile communication system, 2 Base station apparatus, 3 Mobile station apparatus, 4 Communication network, 10 Control part, 11 Calibration weight calculation process control part, 12 Calibration weight calculation part, 20 Storage part, 30 Network interface part, 40 Wireless communication unit, 50 calibration unit, 51 synthesis / distribution unit, 52, 61, 84, 86 T / R switch, 53, 56, 62, 63 RF / IF unit, 54, 66 transmission unit, 55, 69 transmission signal Generator, 57, 71 receiver, 58, 72 detector, 59 second calibration weight basic quantity calculator, 60 base station transmitter / receiver, 64 carrier p transmitter / receiver, 67 antenna weight multiplier, 70 weight calculator, 73 1st calibration weight basic quantity calculation part, 80,88 cave , 81 antenna i unit, 82 an antenna, 83 couplers, 85 a power amplifier, 87 a low noise amplifier, 90 a bus, 100 the base station apparatus main body, 101 an antenna unit.

Claims (2)

In a communication device including communication means for performing communication using at least one of a plurality of frequency channels,
Detecting means for detecting that a predetermined condition is satisfied;
A calibration that controls the communication device to perform a predetermined calibration weight calculation process for at least one of the plurality of frequency channels when the detection unit detects that a predetermined condition is satisfied. Control weight calculation processing control means,
The calibration weight for each of at least one frequency channel calculated by the predetermined calibration weight calculation processing performed by the control of the calibration weight calculation processing control means, and the predetermined condition is satisfied by the detection means Calibration weight for each of the at least one frequency channel calculated by the predetermined calibration weight calculation processing before the detection is detected, and before the detection means detects that the predetermined condition is satisfied Based on the calibration weight for the frequency channel other than the at least one frequency channel calculated by the predetermined calibration weight calculation process, the frequency other than the at least one frequency channel is calculated. A calibration weight estimation means for estimating a calibration weight for the channel,
A communication device comprising: A calibration weight for estimating a calibration weight for calibrating at least one of the amplitude and phase of a communication signal transmitted in a communication apparatus including communication means for performing communication using at least one of a plurality of frequency channels An estimation method,
A detecting step for detecting that a predetermined condition is satisfied;
Wherein when a predetermined condition is detected to have been satisfied in the detection step, among the plurality of frequency channels, to perform at least one calibration weight calculation process of the Jo Tokoro about the frequency channel, controlling the communication device A calibration weight calculation processing control step,
Calibration weight for each of at least one frequency channel calculated by the predetermined calibration weight calculation process performed in the calibration weight calculation process control step, and detection that the predetermined condition is satisfied in the detection step A calibration weight for each of the at least one frequency channel calculated by the predetermined calibration weight calculation process before being performed, and the predetermined before the predetermined condition is detected in the detecting step. And at least one frequency channel based on a calibration weight for a frequency channel other than the at least one frequency channel calculated by the calibration weight calculation process of A calibration weight estimation step of estimating a calibration weight for the frequency channels other than,
A calibration weight estimation method comprising:

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