JP2005167921A - Radio communication method and base station system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the receiving operation of a transceiver diversity terminal. <P>SOLUTION: When a base station system 200 performs radio communication with a transceiver diversity terminal, the base station system 200 extracts a receive response vector signal according to the number of antennae of a terminal device from a transmission signal of the terminal device. For each terminal device, one, which is relatively new in time, out of the receiving response vector signals is stored under management as a first receiving response vector and one, which is relatively old in time, is stored under management as a second receive response vector. Then, the base station system 200 generates a transmission weight signal for enlarging a transmission gain and turning up directivity for the first receiving response vector of the terminal device to be transmitted and for reducing the transmission gain and restricting the directivity for the second receive response vector of the same terminal device and a first receive response vector and a second receive response vector of another terminal device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radio communication technique using radio waves, and more particularly to a radio communication method from a base station apparatus to a terminal apparatus and a base station apparatus using the same.

Mobile phone systems and simplified mobile phone systems have become widespread and are used by many users. In these systems, a terminal device communicates predetermined data using a channel assigned by a base station device. In addition, one base station apparatus assigns a plurality of channels to terminal apparatuses, and multiplexes these terminal apparatuses. In particular, in a mobile phone system and a simple mobile phone system, a time division multiple access (TDMA) method is generally used as a multiplexing technique. The TDMA system is a system in which a time axis is divided at a predetermined time called a time slot and is allocated to each user for multiplexing.

  Further, in order to further increase the data transmission capacity per base station apparatus, a technique for multiplexing terminal apparatuses using a space division multiple access (SDMA) system based on space division in addition to the TDMA system has been studied. . In the SDMA scheme, a base station apparatus multiplexes a plurality of terminal apparatuses by assigning time slots having the same frequency and timing.

  Multiplexing by this SDMA method is generally performed by controlling antenna directivity based on an adaptive array antenna.

  The uplink signal transmitted from the terminal device is received by the array antenna of the base station device, and separated and extracted with reception directivity by adaptive array processing. Further, the downlink signal from the base station apparatus to the terminal apparatus is generated based on the directivity information extracted from the received signal and transmitted with transmission directivity.

This transmission directivity control is performed for each terminal device, and in the direction of an incoming wave of a signal received from a predetermined terminal device, the transmission gain is increased to increase the directivity, while from other terminal devices. In the direction of the incoming wave of the received signal, the transmission gain is attenuated and transmitted in order to suppress directivity. Thereby, even in the same slot and the same frequency, the terminal device can be spatially separated and multiplexed, and the data transmission capacity per base station can be improved.
JP 2002-043995 A

  On the other hand, as a terminal device, a device that performs a diversity operation by transmission / reception has been proposed for the purpose of performing more stable communication under various environments.

  This transmission / reception diversity terminal generally receives signals from a base station apparatus by a plurality of terminal antennas, selects an antenna having a large reception power, processes the received signal, and selects an uplink to the base station apparatus. By operating to transmit from the terminal antenna, the communication is performed on the transmission path in a better condition, and the stability is improved.

  However, when this transmission / reception diversity terminal is connected to the base station apparatus that performs the above-described adaptive array processing, the base station apparatus cannot recognize that the terminal apparatus performs transmission by switching a plurality of antennas. This antenna switching is recognized as a variation in the direction of arrival.

  In addition, the downlink signal from the base station apparatus to the terminal apparatus is transmitted after the directivity is controlled by adaptive array processing. The control is performed by a signal received from a predetermined terminal apparatus for each terminal apparatus. In the direction of the incoming wave, the transmission gain is increased in order to increase the directivity, while in the direction of the incoming wave of the signal received from another terminal device, the transmission gain is attenuated in order to suppress the directivity. Therefore, directivity control is not performed on an antenna that has not been transmitted by the terminal device, that is, an antenna that is not recognized by the base station device.

  For this reason, the antenna that the terminal device does not use for transmission is directed without suppressing the transmission gain for the other terminal device, and the terminal device transmits the signal of the same frequency for the other terminal to the terminal device for the terminal device. The signal is received in a superimposed manner.

  The inventor has recognized the above situation and made the present invention, and an object of the present invention is to provide a wireless communication method for performing spatial multiplexing, a wireless communication method for preventing deterioration of reception performance of a transmission / reception diversity terminal, and It is to provide a used base station apparatus.

One embodiment of the present invention is a base station apparatus.

  The apparatus includes a reception response coefficient calculation unit that calculates reception response coefficients at predetermined intervals based on signals received from a communication target terminal apparatus having a plurality of antennas, and a plurality of reception response coefficient calculation units A storage unit that stores a reception response coefficient, and a transmission response coefficient calculation unit that calculates a transmission response coefficient for a communication target terminal device, reflecting a plurality of reception response coefficients stored in the storage unit. The transmission response coefficient calculation unit increases the gain in the direction to be realized by the reception response coefficient rewritten by the selective update control unit, and in the direction to be realized by the reception response coefficient not rewritten by the selective update control unit. The transmission response coefficient may be calculated so as to reduce the gain.

  A selection update control unit that rewrites a reception response coefficient close to the calculated reception response coefficient among the plurality of reception response coefficients stored in the storage unit with the calculated reception response coefficient may be further provided.

  With the above configuration, the base station apparatus stores and manages the reception response coefficients corresponding to the plurality of antennas included in the terminal apparatus together with the order of rewriting, that is, the old and new order, and reflects the reception response coefficients to the terminal apparatus. Since the transmission response coefficient is generated, in the terminal device that receives the signal from the base station device, the terminal antenna used for the latest transmission receives a signal with large power, while the terminal antenna used for the transmission in the past The signal is received with small power, and stable communication can be performed by clear antenna selection.

  The reception response coefficient calculation unit also calculates reception response coefficients for other terminal devices at predetermined intervals based on signals received from other terminal devices to be connected by spatial multiplexing, and the storage unit receives reception response coefficients. The reception response coefficient for the other terminal device calculated by the calculation unit is also stored, and the transmission response coefficient calculation unit also reflects the reception response coefficient for the other terminal device stored in the storage unit, and transmits the transmission response to the communication target terminal device. A coefficient may be calculated.

  The transmission response coefficient calculation unit increases the gain in the direction to be realized by the reception response coefficient rewritten by the selective update control unit, and the reception response coefficient not rewritten by the selective update control unit, and other terminal devices The transmission response coefficient may be calculated so that the gain in the direction to be realized by each of the reception response coefficients is reduced.

  With the above configuration, when the base station apparatus multiplexes and connects a terminal apparatus having a plurality of antennas with other terminal apparatuses by spatial multiplexing, the terminal antenna used for the latest transmission is connected in the terminal apparatus to be connected On the other hand, a desired signal is received with a large amount of power, while a terminal antenna used for transmission in the past receives both a desired wave and an interference wave from another terminal device with a small amount of power. Incorrect diversity selection is suppressed and stable communication can be performed.

  Further, the transmission response coefficient calculation unit includes a first response response coefficient and a reception response coefficient other than the reception response coefficient stored in the storage unit. A reception response coefficient selection unit that selects a plurality of second reception response coefficients, and a gain in a direction to be realized by the first reception response coefficient, and a gain in a direction to be realized by the second reception response coefficient May further include a calculation unit for calculating a transmission response coefficient to be reduced.

  With the above configuration, when a base station apparatus connects a terminal apparatus having a plurality of antennas simultaneously with other terminal apparatuses by spatial multiplexing, a transmission path with a small correlation between the spatially multiplexed terminal apparatuses is selected, Stable communication can be performed by improving the stability of demultiplexing.

This device is a base station device that transmits and receives signals to and from a terminal device having a plurality of antennas,
The transmission gain for any one of the plurality of antennas may be increased.

  With the above configuration, when transmitting and receiving signals to and from a terminal device having a plurality of antennas, the base station device increases the transmission gain for any one of the plurality of antennas. More stable communication can be performed.

  Further, this apparatus is a base station apparatus that transmits a signal to a terminal apparatus that has a plurality of receiving antennas and performs diversity processing, and stores directivity information for the receiving antennas of the terminal apparatus. And an adaptive array processing unit that performs adaptive array processing based on directivity information and performs transmission directivity control on a receiving antenna of the terminal device, and transmits a signal to the terminal device based on adaptive array processing An adaptive array antenna unit for transmitting a signal to a terminal device, increasing a transmission gain for a desired antenna among the receiving antennas of the terminal device and decreasing a transmission gain for other receiving antennas. Also good.

  With the above configuration, the base station device stores the directivity information for the receiving antenna of the terminal device as viewed from the base station device, and when transmitting a signal to the terminal device, the base station device is adaptive based on the directivity information. In the array processing, among the plurality of receiving antennas of the terminal device, the transmission gain is increased for the antenna that desires reception, and the transmission gain is decreased for the other antennas, so the terminal device is stable. Diversity processing can be performed, and more stable communication can be realized.

  One embodiment of the present invention is a wireless communication method.

  This method calculates a reception response coefficient at a predetermined interval based on a signal received from a communication target terminal apparatus having a plurality of antennas, and includes the calculated plurality of reception response coefficients in the communication target terminal apparatus. More than the number of antennas is stored, and a plurality of reception response coefficients stored in the memory are reflected to calculate a transmission response coefficient for the communication target terminal device.

  Another aspect of the present invention is also a wireless communication method.

  This method calculates each reception response coefficient at a predetermined interval based on signals received from a communication target terminal device having a plurality of antennas and other communication terminals, and calculates the calculated plurality of reception response coefficients. More than the number of antennas is stored in each of the communication target terminal device and the other communication terminal, and the communication target terminal device and the other terminal device stored in the memory reflect a plurality of reception response coefficients, respectively. The transmission response coefficient for is calculated.

  Yet another embodiment of the present invention is a program.

  The program includes a step of calculating a reception response coefficient at a predetermined interval based on a signal received from a communication target terminal device having a plurality of antennas connected via a wireless network, and a plurality of calculated reception responses. Storing a coefficient in a memory that is equal to or greater than the number of antennas of the terminal device to be communicated, and calculating a transmission response coefficient for the terminal device to be communicated by reflecting a plurality of reception response coefficients stored in the memory. .

  Yet another embodiment of the present invention is also a program.

  This program sets the respective reception response coefficients at predetermined intervals based on signals received from a communication target terminal device having a plurality of antennas and other communication terminals, which are connected by spatial multiplexing via a wireless network. A step of calculating, a step of storing a plurality of calculated reception response coefficients in the memory for each of the communication target terminal device and the other communication terminals in the memory, and a communication target terminal device and the other terminals stored in the memory And a device, each of which reflects a plurality of reception response coefficients, and calculates a transmission response coefficient for the terminal device to be communicated.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless communication method which prevents deterioration of the reception performance of a transmission / reception diversity terminal, and a base station apparatus using the same can be provided.

The present embodiment relates to a communication system in which a terminal device that performs diversity processing by transmission and reception and a base station device that performs adaptive array processing are connected and channels are multiplexed by SDMA, and is generated by transmission and reception diversity processing of the terminal device The present invention relates to a base station apparatus that manages reception response vectors as reception response coefficients more than the number of antennas of a terminal apparatus and performs directivity control of transmission signals using the management information in order to prevent deterioration of reception performance of the terminal apparatus. .

  The details will be described below by taking a simple mobile phone system as an example.

  FIG. 1 shows a communication system 10 according to the present embodiment. The communication system 10 includes a first terminal device 100, a second terminal device 104, a base station device 200, and a network 300.

  The first terminal apparatus 100 includes a first terminal antenna 102 a and a second terminal antenna 102 b that are collectively referred to as a terminal antenna 102, and the second terminal apparatus 104 is a first terminal antenna that is generally referred to as a terminal antenna 106. The base station apparatus 200 includes a first base station antenna 202a, a second base station antenna 202b, a third base station antenna 202c, and a fourth base station antenna, which are collectively referred to as a base station antenna 202. 202d.

  The first terminal device 100 is a terminal device that is carried by a user and has a diversity function for transmission and reception. The diversity function in this transmission / reception is such that signals from the base station apparatus 200 are received by the two terminal antennas 102a and 102b, the antenna having the larger reception power is selected and the received signal is processed, and the base station apparatus 200 The uplink also operates to transmit from the selected terminal antenna. Here, since a simple mobile phone system is assumed as the communication system 10, the first terminal device 100 and the second terminal device 104 communicate using a channel assigned by the base station device 200.

  The base station apparatus 200 is a base station apparatus that assigns channels to the first terminal apparatus 100 and the second terminal apparatus 104 and performs wireless communication. The base station apparatus 200 controls antenna directivity by adaptive array processing based on a plurality of base station antennas 202, and a plurality of terminal apparatuses, for example, the first terminal apparatus 100 and the second terminal apparatus 104 are connected by SDMA. Multiplex.

  Furthermore, the base station apparatus 200 is also connected to the network 300.

  FIG. 2 shows a structure of a radio channel assigned by base station apparatus 200. Here, the multiplicity of the spatial axis by the SDMA channel is 2, and the multiplicity of the time axis by the non-SDMA channel, that is, the number of time slots is 4, in which, from the control channel, the channel (2, 1) to the channel A total of six call channels (4, 2) are arranged. One terminal device is assigned to one channel. Note that FIG. 2 shows either the uplink or the downlink, and the other has the same arrangement.

  FIG. 3 shows a burst format of a simple mobile phone system as an example of a burst format used in the present embodiment. This burst format corresponds to the signal of the channel in FIG. A preamble for use in timing synchronization is arranged between the four symbols from the head of the burst, and a unique word is arranged between the following eight symbols. Since the preamble and the unique word are known to the base station apparatus 200, they can be used as a training signal described later.

  FIG. 4 shows the structure of base station apparatus 200.

  The base station apparatus 200 includes a first radio unit 402a, a second radio unit 402b, a third radio unit 402c, a fourth radio unit 402d, a radio signal processing unit 404, a line interface unit 412, and a control unit, which are collectively referred to as a radio unit 402. The wireless signal processing unit 404 includes an array processing unit 406, a demodulation unit 408, and a modulation unit 410. In addition, the first received digital signal 40a, the second received digital signal 40b, the third received digital signal 40c, the fourth received digital signal 40d, and the transmitted digital signal 42, which are collectively referred to as the received digital signal 40 as signals. It includes a transmission digital signal 42a, a second transmission digital signal 42b, a third transmission digital signal 42c, a fourth transmission digital signal 42d, a combined signal 44, a combined signal 70, a pre-separation signal 46, and a pre-separation signal 76.

  The wireless unit 402 performs frequency conversion processing, amplification processing, AD or DA conversion processing, etc., between a baseband signal and a radio frequency signal processed by a wireless signal processing unit 404 described later. In the reception operation, a signal received via the base station antenna 202 and the radio unit 402 is converted into a baseband signal and the reception digital signal 40 is output. In the transmission operation, the baseband transmission digital signal 42 is converted to a radio frequency signal. Convert to signal and output. Here, in order to assume a simple mobile phone system, the radio frequency is set to 1.9 GHz band.

  The array processing unit 406 performs adaptive array antenna signal processing. Here, in order to enable SDMA, adaptive array signal processing for each terminal device is executed. Details will be described later with reference to FIG.

  The demodulator 408 receives the combined signals 44 and 70 that are reception signals for each terminal device processed by the array processor 406, performs demodulation processing, and reproduces the information signal.

  Modulation section 410 modulates the information signal to be transmitted and generates pre-separation signals 46 and 76 that are transmission signals for each terminal device.

  Note that the demodulation unit 408 and the modulation unit 410 function for each terminal device, and the modulation scheme used is π / 4 shift QPSK.

  The line interface unit 412 is an interface with the network 300. Here, it is assumed that the network 300 is an ISDN (Integrated Services Digital Network).

  The control unit 414 controls the operation timing of the entire base station apparatus 200 and controls the radio signal processing unit 404 and the line interface unit 412. Specifically, the wireless signal processing unit 404 performs wireless protocol processing such as assignment of a wireless channel to a terminal device and exchange of a terminal ID and function information, as well as a terminal ID and a used slot number. The management information is stored in the storage unit 522 via the reception response vector selection processing unit 520. In addition, the line interface unit 412 is instructed to start or stop a call connection operation to the network 300 and exchanges information with a center facility (not shown) via the line interface unit 412.

  FIG. 5 shows the structure of the array processing unit 406.

  The array processing unit 406 is a processing unit that performs adaptive array antenna signal processing, and performs adaptive array signal processing for individual terminal devices in order to enable SDMA. Specifically, for example, the first signal processing unit 502 performs signal processing for the first terminal device 100 and the second signal processing unit 540 performs signal processing for the second terminal device 104. In the present embodiment, two terminal devices to be connected are described. However, the present invention is not limited to this. Although not shown in FIG. 5, more terminal devices can be handled by separately providing a processing unit having the same configuration as the first signal processing unit 502.

  Details will be described below.

  The array processing unit 406 includes a first addition unit 550a and a second addition unit 550b collectively referred to as a first signal processing unit 502, a second signal processing unit 540, a reception response vector selection processing unit 520, a storage unit 522, and an addition unit 550. , A third adder 550c and a fourth adder 550d.

  The first signal processing unit 502 includes a combining unit 504, a reception weight vector calculation unit 510, a reference signal generation unit 512, a reception response vector calculation unit 514, a separation unit 530, and a transmission weight vector calculation unit 532. Includes a first multiplying unit 506a, a second multiplying unit 506b, a third multiplying unit 506c, a fourth multiplying unit 506d, and an adding unit 508. The separating unit 530 is collectively referred to as a multiplying unit 538. A first multiplier 538a, a second multiplier 538b, a third multiplier 538c, and a fourth multiplier 538d. Further, a first reception weight signal 50a, a second reception weight signal 50b, a third reception weight signal 50c, a fourth reception weight signal 50d, a reception weight reference signal 52, a reception response reference signal, which are collectively referred to as reception weight signals 50 as signals. 54, reception response vector signal 56, selected reception response vector signal 58, first transmission weight signal 60a, second transmission weight signal 60b, third transmission weight signal 60c, and fourth transmission weight signal collectively referred to as transmission weight signal 60. 60d, first terminal first transmission digital signal 60a, first terminal first transmission digital signal 60b, first terminal first transmission digital signal 60c, first terminal first transmission digital, collectively referred to as first terminal transmission digital signal 62 Contains signal 60d. The configuration of the second signal processing unit 540 is the same as that of the first signal processing unit 502, and thus the description thereof is omitted.

  The reception weight vector calculation unit 510 is a calculation unit that calculates a reception weight signal 50 necessary for weighting the reception digital signal 40 from the reception digital signal 40 and the reception weight reference signal 52. As a specific calculation method, for example, an error signal between the reception weight reference signal 52 as a desired array response and a calculated value obtained by weighting the reception digital signal 40 with the reception weight signal 50 is minimized. The LMS (Least Mean Squares) algorithm and RLS (Recursive Least Squares), which have been proposed as an optimization algorithm based on the minimum mean square error method (MMSE) that obtains an optimal reception weight signal. Calculate by algorithm.

  The multiplier 506 weights the received digital signal 40 with the received weight signal 50, and the adder 508 adds the outputs of the multiplier 506 and outputs the combined signal 44.

  The reference signal generation unit 512 outputs the training signal stored in advance as the reception weight reference signal 52 and the reception response reference signal 54 during the training period. As a training signal during this training period, the preamble and unique word shown in FIG. 3 can be used. On the other hand, after the training period, the composite signal 44 is determined with a predetermined threshold value, and the result is output as a reception weight reference signal 52 and a reception response reference signal 54. Note that the determination does not need to be a hard determination, and may be a soft determination.

  The reception response vector calculation unit 514 calculates a reception response vector signal 56 from the reception digital signal 40 and the reception response reference signal 54 as the reception response characteristic of the signal received from the first terminal apparatus 100. The calculation method of the reception response vector signal 56 may be arbitrary, but is executed based on correlation processing as shown below as an example.

  The received digital signal 40 and the received response reference signal 54 are not only from the first signal processing unit 502 but also by a signal line (not shown) corresponding to the second terminal device 104 of another user. It is assumed that the input is also from 540.

  The reception signal received by the base station antenna 202 and subjected to frequency conversion processing and AD conversion by the radio unit 402 is expressed as the received digital signal 40 by the following expression xj (t) for each antenna (j is the base station). Indicates the station antenna number).

ここで、ｈｋｊはｊ番目の基地局アンテナで受信されたｋ番目の端末装置からの信号の応答係数を、また、ｎｊ（ｔ）はｊ番目の基地局アンテナで受信した信号に含まれる雑音を示す。なお、Ｓｋ（ｔ）はｋ番目の端末装置が送信し基地局装置で受信した信号を示す。

Here, hkj is the response coefficient of the signal from the kth terminal apparatus received by the jth base station antenna, and nj (t) is the noise contained in the signal received by the jth base station antenna. Show. Note that Sk (t) indicates a signal transmitted by the kth terminal apparatus and received by the base station apparatus.

  When the received digital signal 40 at each base station antenna is expressed as a vector, the following equation is obtained.

ここで、〔 〕Ｔは〔 〕の転置を示し、また、Ｘ（ｔ）は入力信号ベクトル、Ｈｋはｋ番目の端末装置からの受信信号の応答係数ベクトル（ｋ＝１，２）、Ｎ（ｔ）は雑音ベクトルを示す。

Here, [] T indicates transposition of [], X (t) is an input signal vector, Hk is a response coefficient vector (k = 1, 2) of a received signal from the kth terminal device, N ( t) represents a noise vector.

  In the above equation, S1 (t) and S2 (t) are known from the separation of user signals by adaptive array processing. Therefore, for example, the ensemble is multiplied by the signal S1 (t) from the first terminal device. Taking the average (time average) gives the following formula:

ここで、Ｅ〔 〕は、〔 〕の時間平均を示すが、平均時間が十分長いと、その平均値は次のようになる。

Here, E [] shows the time average of []. If the average time is sufficiently long, the average value is as follows.

なお、Ｓ１（ｔ）とＳ２（ｔ）、Ｎ（ｔ）とＳ１（ｔ）とのアンサンブル平均は、互いに相関がないことから０としている。

Note that the ensemble averages of S1 (t) and S2 (t) and N (t) and S1 (t) are 0 because they are not correlated with each other.

  Thereby, the reception response vector signal 56 of the signal received from the first terminal device, that is, H1 is obtained by the following equation.

また、２番目以降の端末装置についても、同様にして受信応答ベクトル信号を求めることができる。

Similarly, the reception response vector signal can be obtained for the second and subsequent terminal devices.

  The reception response vector selection processing unit 520 sequentially receives the reception response vector signal 56 for each terminal device calculated by the reception response vector calculation unit 514, performs selection by a predetermined method, and selects a reception response vector signal that meets the conditions. A processing unit to be stored in the storage unit 522.

  FIG. 6 shows the data structure of the storage unit 522. The “terminal ID” is an ID number unique to the terminal device and is a number uniquely assigned to all the terminal devices. The “slot number” is a slot number to which the terminal device is connected. The “first reception response vector” is an antenna on one side of the two antennas included in the first terminal device 100 among the reception response vectors of the first terminal device 100 calculated by the reception response vector calculation unit 510 ( For example, the response vector signal of the received signal estimated to be transmitted from 102a) is stored, and the “second received response vector” is estimated to be transmitted from the other antenna (for example, 102b) of the terminal device. The response vector signal of the received signal is stored. A specific estimation method will be described later with reference to FIG.

  The transmission weight vector calculation unit 532 uses the reception response vector signal stored in the storage unit 522 as the transmission weight signal 60 necessary for weighting the pre-separation signal 46 as a signal to be transmitted to the first terminal apparatus 100. It is a processing unit to calculate based on. For the calculation, it is composed of a temporary storage register 534 that temporarily holds a reception response vector signal and a calculation unit 536 that performs a specific calculation. The function of the temporary storage register 534 will be described later with reference to FIG.

  The calculation method of the transmission weight signal 60 may be arbitrary, but an example is shown below.

  First, the transmission weight signal 60 to be calculated is represented by the following equation.

ここで、ｋはｋ番目の端末装置を、続く１〜４は、基地局アンテナの番号を示す。

Here, k indicates the k-th terminal device, and the subsequent 1-4 indicate base station antenna numbers.

  In the transmission operation, a transmission gain is high for a terminal device that desires communication (k in Equation 6), while a transmission gain is given to a terminal device that does not desire communication (m other than k in Equation 6). Although it is necessary to generate a transmission weight signal to be reduced, the realization thereof can be obtained by satisfying the following conditional expression.

  A condition for a terminal device that desires communication is expressed by the following equation.

また、通信を所望しない端末装置に対する条件は次の式で示される。

Further, the condition for a terminal device that does not desire communication is expressed by the following equation.

これらの条件式は、例えば、前述の受信ウエイトベクトルの算出と同様に、ＬＭＳやＲＬＳのアルゴリズムによりその最適解を得ることができ、その際のウエイトベクトルは、ウィーナー解として次の式で示すことが出来る。

These conditional expressions can be obtained, for example, by the LMS or RLS algorithm in the same manner as the calculation of the reception weight vector described above, and the weight vector at that time is expressed by the following expression as a Wiener solution. I can do it.

ここで、Ｒｘｘは自己相関行列、ｒｘｄは受信信号と参照信号との相関ベクトルである。

Here, Rxx is an autocorrelation matrix, and rxd is a correlation vector between the received signal and the reference signal.

  Multiplier 538 weights pre-separation signal 46 with transmission weight signal 60 and outputs first terminal transmission digital signal 62 to first terminal apparatus 100.

  The adder 550 includes the first terminal transmission digital signal 62 for the first terminal device 100 calculated by the first signal processing unit 502 and the transmission signal for the second terminal device 104 calculated by the second signal processing unit 540. 78 is added for each antenna, and the baseband transmission digital signal 42 is output to the radio unit 402.

  The above configuration can be realized in hardware by a CPU, memory, or other LSI of an arbitrary computer, and is realized in software by a program having a reservation management function loaded in memory. The functional block realized by those cooperation is drawn. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 7 is a flowchart showing selection of a reception response vector signal by the reception response vector selection processing unit 520 and storage in the storage unit 522.

  The selection of the reception response vector signal shown here is performed for the purpose of managing the reception response vector signal for each of a plurality of antennas (for example, two) used by the terminal device for transmission and reception. It functions to store a new received response vector signal.

  Details of the processing are shown below.

  When the connection with the terminal device is started, the reception response vector selection processing unit 520 obtains the terminal ID of the terminal device and the assigned slot number from the control unit 414, and the “identification ID” and “ “Slot number” is stored (S700).

  When synchronization with the terminal device is established and the reception response vector calculation unit 514 starts calculating the reception response vector signal 56 (S702), the reception response vector selection processing unit 520 displays the calculated reception response vector. It is determined whether the signal is the first reception response vector signal (S704). Here, when it is the first reception response vector signal (S704-Y), the reception response vector selection processing unit 520 stores the first reception response vector signal in the storage unit 522 as the “first reception response vector”. Store in the area (S710). On the other hand, when the communication has already been started and the reception response vector signal has been continuously calculated (S704-N), the newly calculated reception response vector signal and the “first reception response vector” in the storage unit 522 are used. Is compared with the received response vector signal stored in (706), and if the difference is not equal to or greater than the predetermined width (S 706 -N), the new received response vector signal is stored in “No. It is determined that the signal is from the same arrival direction as that of the previous reception response vector signal stored in “1 reception response vector”, that is, a new signal in time from the same antenna of the terminal device, and a newly calculated reception response vector signal Is overwritten and updated to “first reception response vector”. On the other hand, as a result of the comparison, if the difference is equal to or greater than a predetermined width (S706-Y), the new reception response vector signal is received in the previous reception stored in the “first reception response vector” of the storage unit 522. It is determined that the signal is transmitted from an antenna different from the response vector signal, that is, a signal transmitted from an antenna different from the received response vector signal stored in the previous “first received response vector” because the diversity function works in the terminal device. Then, the “first reception response vector” in the storage unit 522 is overwritten and moved to the “second reception response vector” (S708), and the newly calculated reception response vector signal is overwritten on the “first reception response vector” (S708). S710).

  Then, the end of communication is confirmed (S712), and if there is a disconnection, the process ends.

  FIG. 8 is a flowchart when the transmission weight vector is generated using the selected reception response vector signal stored in the storage unit 522.

  The processing shown in this flowchart is executed for each terminal device. For example, the first terminal device 100 is performed by the transmission weight vector calculation unit 532 of the first signal processing unit 502, and the second terminal device 104 is processed. The transmission weight vector calculation unit (not shown) of the second signal processing unit 540 performs this.

  With the connection between the terminal device and the base station device, calculation of the reception response vector signal by the reception response vector calculation unit 514, selection of the reception response vector signal by the reception response vector selection processing unit 520, and storage in the storage unit 522 are started. Then, the transmission weight vector calculation unit 532 searches the storage unit 522 for “terminal ID” corresponding to the first terminal device 100, and uses the reception response vector signal stored in the “first reception response vector”. The temporary storage register A (S800) and the reception response vector signal stored in the “second reception response vector” are stored and held in the temporary storage register B (S802).

  Next, the transmission weight vector calculation unit 514 determines whether there is another terminal device multiplexed in the same slot as the first terminal device 100 (S804). Specifically, referring to the “slot number” field in storage unit 522, it is confirmed whether there is a terminal device having the same slot number as that of first terminal device 100. If it is determined that there is a terminal device being multiplexed (S806-Y), the “first reception response vector” and “second reception response vector” of the corresponding terminal device are read, and the temporary storage registers C , D (S806).

  On the other hand, when there are no multiple terminals (S804-N) or when the additional storage in S806 is completed, the arithmetic unit 536 refers to the reception response vector signal stored in the temporary storage register 534, and the first terminal apparatus 100 The transmission weight signal 60 is calculated for (S808). The transmission weight signal 60 uses, for example, the transmission weight signal generation formula described above, and has a large transmission gain with respect to the reception response vector signal of the temporary storage register A, while the reception of the temporary storage registers B, C, and D. The response vector signal is calculated so as to reduce the transmission gain.

  A conceptual diagram of the state of transmission directivity control by the calculated transmission weight signal is shown in FIG.

  The downlink signal (solid line) transmitted from the base station apparatus 200 to the first terminal apparatus 100 is assumed to be transmitted to the second terminal antenna 102b when the first terminal apparatus uses the second terminal antenna 102b for the latest transmission. On the other hand, a beam that increases the transmission gain is formed on the first terminal antenna 102 a of the terminal device and the two terminal antennas 106 of the second terminal device 104. Further, in the case of multiple connection of terminal devices, the signal for the second terminal device 104 transmitted from the base station device 200 is assumed that the second terminal device has used the second terminal antenna 106b the latest. The second terminal antenna 106b has a large transmission gain, while the second terminal antenna 106a of the same terminal apparatus and the two terminal antennas 102 of the first terminal apparatus 100 have beams that reduce the transmission gain. Form.

  Returning to FIG. 8, the end of communication is confirmed (S810). If there is a disconnection, the process ends.

  The operation of base station apparatus 200 having the above configuration will be described.

  In the following description, a state where only the first terminal device 100 is connected to the base station device 200 (that is, a state where spatial multiplexing by SDMA is not performed) is performed first, and then the same slot as the first terminal device 100 is used. Assuming a state where the second terminal device 104 is multiplex-connected to the same frequency (that is, a state where spatial multiplexing by SDMA is performed), signal transmission / reception processing for each first terminal device 100 will be described in detail.

  In addition, it is assumed that the first terminal device 100 and the second terminal device 104 to be connected are both transmission / reception diversity terminals and are terminal devices having a function of switching an antenna used for transmission / reception in a timely manner according to a reception state.

  When the base station apparatus 200 receives a connection request from the first terminal apparatus 100, the control unit 414 performs radio protocol processing including radio channel allocation, and sets a predetermined frequency and slot (assuming that the second slot is assigned). Initiate a wireless connection at (assuming use). At this time, the processing of the wireless protocol is specifically executed by the control unit 414 of the base station apparatus 200, and the control unit 414 transmits the wireless channel transmitted from the first terminal apparatus 100 in this processing. A “terminal ID” indicating the identification of the terminal device is extracted from the allocation request message and the like, and the reception response vector selection processing unit 520 is sent together with the slot number (# 2 indicating the second slot) “slot number” used in this communication. To the storage unit 522.

  Due to the start of the wireless connection, the signal transmitted from the first terminal device 100 is input to the array processing unit 406 as the received digital signal 40 for each antenna via the base station antenna 202 and the radio unit 402 of the base station device 200. The The received digital signal 40 is a radio signal that is transmitted from the first terminal device 100 and then received by the base station device 200 via the radio wave propagation path. Depending on the situation of the radio wave propagation path, In addition to being affected by reflection, diffraction, scattering, etc., it is a signal including interference wave components and other various noise components due to other signals of the same frequency.

  The received digital signal 40 input to the array processing unit 406 is input to the first signal processing unit 502 that performs transmission / reception signal processing on the first terminal device 100. The received digital signal 40 is output as a combined signal 44 obtained by extracting the transmission signal of the first terminal apparatus 100 after removing or reducing an interference signal component that is an unnecessary signal component.

  Note that, as a method for generating the synthesized signal 44 from the received digital signal 40, a case using the least square error method (MMSE) will be described as an example.

  The least square error method is an algorithm for obtaining an optimum received weight signal by minimizing a difference between a reference signal which is a desired array response and an array output signal. In this algorithm, a desired signal itself is required as a reference signal. For example, in a simple mobile phone system, a preamble or a unique word training signal (FIG. 3) included in a signal received from a terminal device is a base signal. This signal is known to the station apparatus 200, and this signal sequence can be used as a reference signal.

  That is, the reference signal generation unit 512 receives a training signal corresponding to the first terminal device 100 stored in advance in a memory (not shown) during a period in which a training signal such as a preamble or a unique word is received in the reception slot. To the reception weight vector calculation unit 510, and the reception weight vector calculation unit 510 separates and extracts the signal of the first terminal device 100 from the reception digital signal 40 using the training signal as the reception weight reference signal. The reception weight signal 50 is calculated. Then, after the training period, the reference signal generation unit 512 determines the synthesized signal 44 with a predetermined threshold value, outputs the result as the reception weight reference signal 52, and the reception weight vector calculation unit 510 The same calculation is performed.

  Now, when the output of the synthesized signal 44 in the first terminal apparatus 100 is started from the received digital signal 40, the first signal processing unit 502 starts calculating the received response vector signal 56. The reception response vector signal 56 is a signal indicating the reception response characteristic of the received signal, and is calculated from the reception digital signal 40 and the reception response reference signal 54. As a specific method, for example, the calculation can be performed by the above-described equations 1 to 5.

  When the calculation of the reception response vector signal 56 starts, it is selectively stored in the storage unit 522 by the procedure detailed in FIG. Note that the two signals, “first reception response vector” and “second reception response vector” stored in the storage unit 522 by this operation, are the two antennas provided in the first terminal device 100, and the reception response to each. In particular, the signal stored in the “first reception response vector” is a signal indicating the reception response characteristic of the most recently used antenna out of the two antennas.

  Now, when the selective storage of the reception response vector signal 56 in the storage unit 522 is started, the transmission weight vector calculation unit 532 outputs the pre-separation signal 46 that is a signal to be transmitted to the first terminal device 100. Calculation of the transmission weight signal 60 is started. A specific calculation method of this signal can be calculated by, for example, Equation 6 to Equation 9 described above.

  Note that the transmission weight signal 60 calculated here is the first terminal apparatus because the terminal apparatus connected to the base station apparatus 200 is only the first terminal apparatus 100 and spatial multiplexing by SDMA is not performed. For the “first reception response vector” of 100, the beam is directed by increasing the transmission gain, while for the “second reception response vector” of the first terminal apparatus 100, the transmission gain is decreased. By doing so, it becomes a signal to suppress the beam.

  When the transmission weight signal 60 is calculated, the multiplication unit 538 weights the pre-separation signal 46 that is a signal to be transmitted, and the first terminal for the first terminal device 100 separated for each antenna. It is output as a transmission digital signal 62.

  The output first terminal transmission digital signal 62 is input to the adder 550, but is output to the radio unit 402 as the transmission digital signal 42 on the assumption that no other terminal device is connected. The signal is transmitted from the base station antenna 202 to the first terminal apparatus 100 after performing DA conversion, frequency conversion processing, and further amplification processing.

  Now, a signal with directivity transmitted from the base station apparatus 200 to the first terminal apparatus 100 is strongly directional on one side with respect to the two terminal antennas 102 included in the first terminal apparatus 100, and the other side. A beam with reduced directivity is formed. As a result, in the first terminal apparatus 100, the antenna used for the latest transmission (for example, the terminal antenna 102a) has a large power, while the antenna not used for the latest transmission (for example, the terminal antenna 102b) has a small power. Received with power, stable antenna selection is performed.

  Next, the number of terminals connected to the base station apparatus 200 increases, and the second terminal apparatus 104 is multiplexed and connected to the same slot and the same frequency as the first terminal apparatus 100 (that is, spatial multiplexing by SDMA is performed) State) will be described.

  When the base station apparatus 200 receives a connection request from the second terminal apparatus 104, the base station apparatus 200, in the same way as the connection with the first terminal apparatus 100, uses a wireless protocol such as allocation of a radio channel by the control unit 414. Processing is performed, and information such as “terminal ID” and “slot number” is stored in the storage unit 522 via the reception response vector selection processing unit 520.

  When the wireless connection is started, the received digital signal 40 input to the array processing unit 406 is input to the first signal processing unit 504, and processing of transmission / reception signals for the first terminal device 100 is started. The received digital signal 40 includes a signal from the second terminal device 104 in addition to a signal from the first terminal device 100, and it is necessary to remove this signal.

  Even in this removal, the transmission signal of the first and second terminal devices is superimposed by considering the signal from the second terminal device 104 as one of the interference waves by the aforementioned least square error method. The signal of the first terminal apparatus 100 is extracted from the signal, and the synthesized signal 44 can be obtained.

  Also, in the calculation of the reception response vector signal 56 by the reception response vector calculation unit 514, the calculation can be performed by the above-described equations 1 to 5.

  When calculation of the reception response vector signal 56 starts, the reception response vector selection processing unit 520 selects the “first reception response vector” and the “second reception response vector” of the first terminal device 100, and the storage unit Stored in 522.

  Although the processing for the first terminal apparatus 100 has been described with respect to the calculation of the reception weight signal and the generation of the combined signal, and further the calculation, selection and storage of the reception response vector signal so far, the second terminal The same processing is performed in parallel in the second signal processing unit 540 for the device 104 as well. In this processing, except that the signal from the first terminal device 100 is considered as one of the interference waves and that the training signal related to the second terminal device 104 is used, the first signal processing unit 502 and the above-described In the same process, a signal of the second terminal device 104 is extracted as a synthesized signal 70 from a signal in which signals from the first and second terminal devices are superimposed, and is stored in the storage unit 522 in the second terminal device 104. “First reception response vector” and “second reception response vector” are stored.

  Now, when the selective storage of the reception response vector signal in the storage unit 522 is started, the transmission weight vector calculation unit 532 outputs the pre-separation signal 46 that is a signal to be transmitted to the first terminal device 100. The calculation of the transmission weight signal 60 is started. A specific calculation method of this signal can be calculated by, for example, Equation 6 to Equation 9 described above.

  Note that the transmission weight signal 60 calculated here is the “first reception response vector” of the first terminal device 100 because the first terminal device 100 and the second terminal device 104 are spatially multiplexed by SDMA. In contrast, the beam is directed with a larger transmission gain, while the “second reception response vector” of the first terminal device 100 and the “first reception response vector” and “second” of the second terminal device 104 For the “reception response vector”, the transmission gain is reduced and the beam is not directed.

  When the transmission weight signal 60 is calculated, the multiplication unit 538 weights the pre-separation signal 46 which is a signal to be transmitted, and transmits the first terminal to the first terminal device 100 separated for each antenna. Output as a digital signal 62.

  The output first terminal transmission digital signal 62 is added by the adder 550 to the second terminal transmission digital signal 78 transmitted from the second signal processing unit 540 to the second terminal device 104 and transmitted. The digital signal 42 is transmitted from the base station antenna 202 after undergoing DA conversion, frequency conversion processing, and further amplification processing in the wireless unit 402.

  According to the present embodiment, when a base station apparatus that performs adaptive array processing wirelessly transmits a signal to a terminal apparatus that performs diversity processing by transmission and reception, the terminal apparatus transmits to the terminal antenna used for the latest transmission. To increase directivity by increasing gain, and to reduce directivity by reducing transmission gain for terminal antennas used for transmission in the past and all terminal antennas of other terminal devices The transmission weight signal is generated and wireless transmission is performed.

  As a result, in the terminal device, the terminal antenna used for the latest transmission receives a desired signal with high power, while the terminal antenna used for transmission in the past receives both the desired wave and the interference wave with low power. Thus, an erroneous diversity operation due to the synthesis of the desired wave and the interference wave is suppressed, and stable communication can be performed.

  In the present embodiment, transmission weight vector calculation section 532 uses a “first reception response vector” and a “second reception response vector” calculated for each terminal device, and sets a new “first reception response vector” in terms of time. Processing was performed to increase the transmission gain. However, the present invention is not limited to this. For example, in the case of performing spatial multiplexing, a combination of reception response vector signals having the smallest spatial correlation between terminal devices from two reception response vector signals stored for each terminal device. And the transmission gain can be increased with respect to the received response vector signal.

  The procedure is described below.

  FIG. 10 is a flowchart when a correlation coefficient is calculated to generate a transmission weight vector.

When “first reception response vector” and “second reception response vector” are selected in each terminal device by the reception response vector prefix phrase processing unit 520, the transmission weight vector calculation unit 532 displays the first terminal device 100. “First reception response vector” and “second reception response vector”, and “second reception response vector” and “second reception response vector” of the second terminal device 104 are read from the storage unit 522, respectively, and the temporary storage register The data are stored in A to D of 534 (S1000).
Then, the respective correlations between the two reception response vectors of the first terminal device 100 and the two reception response vectors of the second terminal device 104 are calculated (S1002), and their magnitudes are compared. A combination of minimum values is selected (S1004).

  As a result, for example, when the correlation is minimized by the combination of the temporary storage registers A and C, the “first reception response vector” of the first terminal device 100 stored in the temporary storage register A is obtained. Increases the transmission gain, and on the other hand, the “second reception response vector” of the other first terminal device 100, the “first reception response vector” and the “second reception response vector” of the second terminal device 104. In response to this, a transmission weight signal 60 for reducing the transmission gain is generated (S1006).

  According to the present embodiment, in a base station apparatus that performs adaptive array processing, when a signal is wirelessly transmitted to a terminal apparatus that performs diversity processing by transmission and reception, a transmission path that reduces the correlation between the terminal apparatuses is selected and multiplexed. The stability of separation is improved and stable communication can be performed.

  In the above, it demonstrated based on embodiment of this invention. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In the present embodiment, the number of antennas included in the terminal device and the base station device and the number of multiplexing of the terminal devices are illustrated by specific numerical values. However, the present invention is not limited to this. For example, the number may be larger or smaller. That is, it is only necessary to manage the reception response vector according to the number of antennas provided in the terminal device.

1 shows a communication system according to the present embodiment. 2 shows the structure of the radio channel of FIG. The burst format of FIG. 1 is shown. The structure of the base station apparatus of FIG. 1 is shown. The structure of the array processing part of FIG. 4 is shown. The data structure of the memory | storage part of FIG. 5 is shown. 5 is a flowchart showing selection of a reception response vector signal in FIG. 4 and storage in a storage unit. 5 shows a flowchart when generating the transmission weight vector of FIG. The conceptual diagram which represents typically the state of the transmission directivity control of FIG. 6 shows a flowchart when generating a transmission weight vector by calculating the correlation coefficient of FIG.

Explanation of symbols

10 communication system, 100 first terminal device, 102 terminal antenna, 104 second terminal device, 106 terminal antenna, 200 base station device, 300 network, 202 base station antenna, 402 radio unit, 404 radio signal processing unit, 406 Array processing unit, 408 demodulation unit, 410 modulation unit, 412 line interface unit, 414 control unit, 502 first signal processing unit, 504 synthesis unit, 506 multiplication unit, 508 addition unit, 510 reception weight vector calculation unit, 512 reference signal Generation unit, 514 reception response vector calculation unit, 520 reception response vector selection processing unit, 522 storage unit, 530 separation unit, 532 transmission weight vector calculation unit, 540 second signal processing unit, 550 addition unit, 538 multiplication unit, 40 reception Digital signal, 42 Transmit digital signal , 44 composite signal, 46 signal before separation, 50 reception weight signal, 52 reception weight reference signal, 54 reception response reference signal, 56 reception response vector signal, 58 reception response vector signal after selection, 60 transmission weight signal, 62 first terminal Transmission digital signal, 70 synthesized signal, 76 signal before separation.

Claims (11)

A reception response coefficient calculation unit that calculates a reception response coefficient at a predetermined interval based on a signal received from a communication target terminal device having a plurality of antennas;
A storage unit for storing a plurality of reception response coefficients calculated by the reception response coefficient calculation unit;
A base station apparatus comprising: a transmission response coefficient calculation unit that calculates a transmission response coefficient for the communication target terminal apparatus reflecting a plurality of reception response coefficients stored in the storage unit.   2. The selective update control unit that rewrites a reception response coefficient close to the calculated reception response coefficient among the plurality of reception response coefficients stored in the storage unit with the calculated reception response coefficient. Base station equipment.   The transmission response coefficient calculation unit increases the gain in the direction to be realized by the reception response coefficient rewritten by the selective update control unit, and the direction to be realized by the reception response coefficient not rewritten by the selective update control unit 3. The base station apparatus according to claim 2, wherein a transmission response coefficient that reduces a gain to the base station is calculated. The reception response coefficient calculation unit also calculates a reception response coefficient for the other terminal device at a predetermined interval based on a signal received from another terminal device to be connected by spatial multiplexing,
The storage unit also stores a reception response coefficient for the other terminal device calculated by the reception response coefficient calculation unit,
The transmission response coefficient calculating unit calculates a transmission response coefficient for the communication target terminal device by reflecting reception response coefficients for other terminal devices stored in the storage unit. Item 3. The base station apparatus according to Item 2.   The transmission response coefficient calculation unit increases the gain in the direction to be realized by the reception response coefficient rewritten by the selective update control unit, and the reception response coefficient not rewritten by the selective update control unit, and other terminal devices 5. The base station apparatus according to claim 4, wherein a transmission response coefficient that reduces a gain in a direction to be realized by each of the reception response coefficients is calculated. The transmission response coefficient calculation unit includes, as a first reception response coefficient, a reception response coefficient whose correlation with other terminal devices is reduced among reception response coefficients stored in the storage unit,
A reception response coefficient selection unit that selects a reception response coefficient of the storage unit other than the first reception response coefficient as a second reception response coefficient;
A calculation unit that calculates a transmission response coefficient that increases the gain in the direction to be realized by the first reception response coefficient and decreases the gain in the direction to be realized by the second reception response coefficient;
The base station apparatus according to claim 4, further comprising: A base station device that transmits a signal to a terminal device that has a plurality of receiving antennas and performs diversity processing,
A directivity information storage unit that stores directivity information for the receiving antenna of the terminal device;
An adaptive array processing unit that performs adaptive array processing based on the directivity information and performs transmission directivity control on the reception antenna of the terminal device;
An adaptive array antenna unit for transmitting a signal to the terminal device based on the adaptive array processing;
A base station apparatus characterized in that, when a signal is transmitted to the terminal apparatus, a transmission gain for a desired antenna among reception antennas of the terminal apparatus is increased and a transmission gain for other reception antennas is decreased. Calculate a reception response coefficient at a predetermined interval based on a signal received from a communication target terminal device having a plurality of antennas,
Storing the calculated plurality of reception response coefficients in a memory in which reception response coefficients calculated in the past equal to or greater than the number of antennas of the terminal device to be communicated are stored;
A wireless communication method for calculating a transmission response coefficient for the communication target terminal device, reflecting a plurality of reception response coefficients stored in the memory. Calculate each reception response coefficient at a predetermined interval based on signals received from a communication target terminal device having a plurality of antennas and other communication terminals,
The calculated plurality of reception response coefficients are stored in a memory in which reception response coefficients calculated in the past equal to or more than the number of antennas are stored in each of the communication target terminal device and each of the other communication terminals,
A wireless communication method characterized in that a transmission response coefficient for the communication target terminal apparatus is calculated by reflecting a plurality of reception response coefficients for each of the communication target terminal apparatus and other terminal apparatuses stored in the memory. Calculating a reception response coefficient at a predetermined interval based on signals received from a communication target terminal device having a plurality of antennas connected via a wireless network;
Storing the calculated plurality of reception response coefficients in a memory in which reception response coefficients calculated in the past equal to or greater than the number of antennas of the communication target terminal device are stored;
A program for causing a computer to execute a step of calculating a transmission response coefficient for the communication target terminal device by reflecting a plurality of reception response coefficients stored in the memory. Calculating each reception response coefficient at a predetermined interval based on signals received from a communication target terminal device having a plurality of antennas and other communication terminals connected in a spatial multiplexing manner via a wireless network; ,
Storing the plurality of calculated reception response coefficients in a memory in which reception response coefficients calculated in the past equal to or more than the number of antennas are stored in each of the communication target terminal device and the other communication terminal;
A program for causing a computer to execute a step of calculating a transmission response coefficient for the communication target terminal device by reflecting a plurality of reception response coefficients for each of the communication target terminal device and other terminal devices stored in the memory .

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