JP4162522B2 - Radio base apparatus, transmission directivity control method, and transmission directivity control program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio base apparatus, a transmission directivity control method, and a transmission directivity control program, and an adaptive array radio base apparatus in which a plurality of mobile terminal apparatuses including a mobile terminal apparatus having an adaptive array function can be spatially multiplexed. And a transmission directivity control method and a transmission directivity control program in such a radio base apparatus.
[0002]
[Prior art]
2. Description of the Related Art In recent years, mobile communication systems (for example, Personal Handyphone System: hereinafter referred to as PHS), which are rapidly developing, increase traffic between a radio base device (hereinafter referred to as a base station) and a mobile terminal device (hereinafter referred to as a terminal). In order to improve the frequency utilization efficiency of radio waves in response to the above, a method for extracting a received signal from a desired specific terminal by adaptive array processing has been proposed particularly in a base station (see, for example, Non-Patent Document 1). ).
[0003]
In summary, adaptive array processing is adaptively controlled by calculating a reception weight vector composed of reception coefficients (weights) for each antenna based on signals received from a terminal by an array antenna composed of a plurality of antennas of a base station. This is a process of accurately extracting a signal from a specific terminal user.
[0004]
Furthermore, using this adaptive array processing technique, a space division multiple access system (SDMA) that can spatially multiplex terminals of multiple users to a base station by spatially dividing the same time slot of the same frequency. Multiple Access or PDMA (Path Division Multiple Access) has been proposed (see Non-Patent Document 2). In this SDMA system, signals from each of a plurality of user terminals are separated and extracted by the above-described adaptive array processing at the base station.
[0005]
In a spatial multiplex base station capable of spatial multiplex connection employing such adaptive array processing, a reception weight vector calculator for calculating such a reception weight vector for each symbol of a reception signal of a specific terminal user is provided. The reception weight vector calculator calculates a complex multiplication sum (array output signal) of the reception signal and the calculated reception weight vector in a known reference signal interval (weight estimation interval) provided at the head portion of each frame of the reception signal. Then, the process of converging the reception weight vector so as to reduce the square of the error with the known reference signal, that is, the adaptive array process for converging the reception directivity from the specific terminal user is executed.
[0006]
In adaptive array processing, the convergence of the received weight vector is adaptively performed according to fluctuations in the propagation characteristics of the time and signal radio wave, and interference components and noise are removed from the received signal. The received signal is extracted.
[0007]
In such a received weight vector calculator, an RLS (Recursive Least Squares) algorithm, which is an algorithm for learning weights by the steepest descent method MMSE (Minimum Mean Square Error) based on the square of the error between the array output signal and the reference signal. Adaptive array algorithms such as LMS (Least Mean Square) algorithm and SMI (Sample Matrix Inversion) algorithm are used. Such RLS algorithm, LMS algorithm, SMI algorithm and the like are well-known techniques in the field of adaptive array processing.
[0008]
The spatial multiplexing base station further determines the transmission directivity for the terminal user by weighting the transmission signal with a transmission weight vector obtained by copying the reception weight vector calculated in this way for each terminal user.
[0009]
A method of controlling the directivity of a transmission signal with a transmission weight vector obtained by copying the reception weight vector calculated by such an adaptive array algorithm is known, and is disclosed in Non-Patent Document 3, for example.
[0010]
On the other hand, there is a known method of estimating the terminal arrival direction (so-called reception response vector) from the received signal and estimating the transmission weight from the received response vector, instead of copying the received weight vector as it is and using it as the transmission weight vector. (For example, see Patent Document 1 and Patent Document 2).
[0011]
With the adaptive array technology as described above, the spatial multiplexing base station forms a transmission weight for each terminal so as to direct the beam of the transmission radio wave in the direction of the desired user terminal and the null of the transmission radio wave in the direction of the interference user terminal. To send.
[0012]
FIG. 12 shows how a transmission wave from a base station works when viewed from each terminal when two terminal users are spatially multiplexed with a spatial multiplexing base station (the number of multiplexing is two or two). It shows a table to explain.
[0013]
In the example of FIG. 12, a spatial multiplexing base station (hereinafter also simply referred to as a base station) includes a transmission weight W1 that directs a beam of transmission radio waves toward terminal 1 and a null toward terminal 2 by the above-described adaptive array processing, It is assumed that the transmission weight W2 that directs the beam of the transmission radio wave to 2 and directs the null to the terminal 1 is combined and transmitted from the array antenna.
[0014]
In this case, when viewed from the terminal 1, the signal formed and transmitted by the weight W1 acts as a desired wave having a beam directed to the terminal, and the signal transmitted by the weight W2 is an interference in which a null is directed to the terminal. Acts as a wave.
[0015]
On the other hand, when viewed from the terminal 2, the signal transmitted by the weight W2 acts as a desired wave having a beam directed to the terminal, and the signal transmitted by the weight W1 acts as an interference wave having a null directed to the terminal. To do.
[0016]
In such an example, if the beam and null directions are accurately controlled, the interference wave transmitted to the terminal 1 by the weight W2 and the interference wave transmitted to the terminal 2 by the weight W1 are both close to zero. Thus, the spatial multiplex connection of the terminal 1 and the terminal 2 to the base station is satisfactorily realized.
[0017]
However, the beam and null direction control may shift due to a decrease in the reception level itself at the terminal, an increase in reception level difference between a plurality of terminals, high-speed movement of the terminal, and the like.
[0018]
In such a case, an interference wave is radiated to each terminal (in the example of FIG. 12, the transmission signal with the weight W2 for the terminal 1 and the transmission signal with the weight W1 for the terminal 2), and the communication quality is deteriorated. Will be invited.
[0019]
On the other hand, in recent years, adaptive array terminals equipped with the above-described adaptive array function are being developed in terminals. In such an adaptive array terminal, adaptive array processing is performed inside the terminal for signals received by a plurality of (for example, two) antennas.
[0020]
Therefore, it is assumed that such an adaptive array terminal is spatially multiplexed with a spatial multiplexing base station.
[0021]
One of the features of adaptive array processing is the removal of interference waves from the received signal as described above. Therefore, in the case where the terminal is an adaptive array terminal, it is possible to exhibit interference removal ability even if an interference wave is radiated to the terminal basically.
[0022]
[Patent Document 1]
International Publication No. WO00 / 79702 Pamphlet
[0023]
[Patent Document 2]
JP 2002-43995 A
[0024]
[Non-Patent Document 1]
Toshinori Iinuma, et al., “Adaptive Array Antenna PHS Base Station”, “SANYO TECHNICICAL REVIEW”, Sanyo Electric Co., Ltd., issued May 1, 2000, Vol. 32, No. 1, p. . 80-88
[0025]
[Non-Patent Document 2]
Yoshiharu Doi et al., “Space Division Multiple Access PHS Base Station”, “SANYO TECHNICICAL REVIEW”, Sanyo Electric Co., Ltd., issued December 10, 2001, Vol. 33, No. 3, p. . 93-101
[0026]
[Non-Patent Document 3]
Shuichi Tsujioka, “Mobile Communications”, Ohmsha, published on May 25, 1998, p. 283-312
[0027]
[Problems to be solved by the invention]
However, when performing adaptive array reception, if there is a difference between the arrival directions of the desired wave and the interference wave, the interference removal capability can be exhibited, but if there is no difference in the arrival direction, the interference wave is removed. It is difficult.
[0028]
As described above, assuming that the adaptive array terminal is spatially connected to the spatial multiplexing base station, if the desired wave and the interference wave are coming from the same direction, the adaptive array terminal removes the interference wave. Can not do it.
[0029]
In the conventional spatial multiplexing base station, the transmission weights W1 and W2 in the example of FIG. 12 are formed and transmitted by all the antennas constituting the array antenna. That is, since signals were transmitted to all of the terminals 1 and 2 using all the antennas, each of the terminals 1 and 2 seemed to have the desired wave and the interference wave coming from the same direction.
[0030]
With reference to FIG. 13, the arrival directions of the desired wave and the interference wave viewed from the terminal side will be described. Referring to FIG. 13, the conventional spatial multiplexing base station transmits to both terminal 1 and terminal 2 using all the array antennas including four antennas ANT1, ANT2, ANT3, and ANT4.
[0031]
Of the signals radiated from the respective antennas, the terminal 1 signal (S1) whose beam is directed toward the terminal 1 and null toward the terminal 2 is represented by a thin solid arrow, and the terminals 1 and A vector composition of the signal S1 radiated to the terminal 2 is represented by a thick black thick arrow.
[0032]
On the other hand, among the signals radiated from each antenna, the terminal 2 signal (S2) whose beam is directed to the terminal 2 and null is directed to the terminal 1 is represented by a thin one-dot chain arrow, and from all four antennas. A vector composition of the signal S2 radiated to the terminal 1 and the terminal 2 is represented by a thin black thick arrow.
[0033]
As described above, when the direction of the beam and the null of the transmission signal cannot be satisfactorily performed due to the movement of the terminal or the like, the terminal 1 signal (S1) and the interference wave, which are desired waves, are viewed from the terminal 1. It seems that a certain terminal 2 signal (S2) is coming from the same direction. From the viewpoint of the terminal 2, the terminal 2 signal (S2) as a desired wave and the terminal 1 signal (S1) as an interference wave are from the same direction. It will appear to have arrived.
[0034]
As described above, in the conventional spatial multiplexing base station, transmission is performed by all antennas of the array antenna toward all of a plurality of terminals that are spatially multiplexed to the base station. When the control could not be performed satisfactorily, the desired wave and the interference wave appeared to arrive from the same direction at each terminal.
[0035]
As described above, the adaptive array reception exhibits the interference removal capability only when there is a difference between the arrival directions of the desired wave and the interference wave. In such a case, the adaptive array function is installed in the terminal. However, such an adaptive array terminal cannot remove the interference wave and extract only the desired wave, which may cause deterioration in communication quality and area performance.
[0036]
Therefore, an object of the present invention is to make it possible for a terminal equipped with an adaptive array function to have a sufficient interference cancellation function by making a difference in the arrival directions of desired waves and interference waves reaching each terminal from the spatial multiplexing base station. It is to provide a radio base apparatus, a transmission directivity control method, and a transmission directivity control program that can be exhibited.
[0037]
[Means for Solving the Problems]
According to one aspect of the present invention, M (M is 2 or more and smaller than N) by controlling the directivity of N (N is an integer of 3 or more) antennas arranged in a discrete manner in real time. A radio base apparatus that allows an (integer) number of mobile terminal apparatuses to perform spatial multiplexing connection includes adaptive array processing means, reception response vector calculation means, antenna combination selection means, and transmission weight vector calculation means. The adaptive array processing means performs adaptive array processing on the signals received by the N antennas and extracts received signals from each of the M mobile terminal apparatuses. The reception response vector calculation means calculates the reception response vectors of M mobile terminal apparatuses spatially connected in a multiplexed manner based on the signals received by the N antennas and the extracted reception signals. The antenna combination selection means selects and assigns a different combination of antennas among the N antennas to each of the M mobile terminal apparatuses connected in space. The transmission weight vector calculation means extracts reception response vectors respectively corresponding to different combinations of antennas selected for each mobile terminal device from the calculated reception response vectors, and based on the extracted reception response vectors, A transmission weight vector for controlling the transmission directivity of the antenna is calculated for each of the corresponding mobile terminal apparatuses connected in multiplex.
[0038]
Preferably, the transmission weight vector calculation means directs a beam of transmission radio waves to each of the M mobile terminal apparatuses connected in space, and directs a null of the transmission radio wave to other mobile terminal apparatuses. Calculate the transmit weight vector to be directed.
[0039]
Preferably, the number of antenna combinations is selected between M and (N-1).
[0040]
Preferably, the antenna combination selection unit selects a combination of antennas by a combination fixed in advance.
[0041]
Preferably, the antenna combination selection unit selects an antenna combination based on the calculated reception response vector of each mobile terminal apparatus.
[0042]
Preferably, the antenna combination selection means includes means for calculating the magnitude of the reception response vector of each of the N antennas corresponding to each of the mobile terminal devices connected in space, and the calculated N antennas. Means for selecting the combination of antennas corresponding to the magnitudes of reception response vectors corresponding to the number of antennas selected in order from the largest reception response vector.
[0043]
Preferably, the antenna combination selection unit corresponds to each of the mobile terminal devices that are spatially multiplexed, for each of the N antennas, the reception response vector of each mobile terminal device other than the mobile terminal device. The sum of the magnitudes of reception response vectors for the number of antennas selected in order from the largest total value of the magnitudes of the received response vectors of the N antennas, and the means for calculating the total magnitude Means for selecting a combination of antennas corresponding to the value.
[0044]
Preferably, the antenna combination selection means calculates the correlation value of the reception response vectors between the mobile terminal devices connected in space, corresponding to each of the predetermined antenna combinations corresponding to the number of antennas to be selected. Means for calculating, and means for selecting a combination of antennas corresponding to each of the mobile terminal apparatuses that are spatially multiplexed so as to minimize the sum of correlation values between the mobile terminal apparatus and other mobile terminal apparatuses; including.
[0045]
According to another aspect of the present invention, M (M is 2 or more and smaller than N) by controlling the directivity of N (N is an integer of 3 or more) discretely arranged antennas in real time. An integer) transmission directivity control method in a radio base station that allows spatial multiplex connection is performed. An adaptive array process is performed on signals received by N antennas, and each of the M mobile terminal apparatuses is subjected to adaptive array processing. Extracting received signals from the N antennas, calculating received response vectors of M mobile terminal apparatuses spatially multiplexed based on the signals received by the N antennas and the extracted received signals; Selecting and assigning different combinations of antennas out of N antennas to each of M mobile terminal apparatuses connected in space, A reception response vector corresponding to each combination of different antennas selected for each mobile terminal device is extracted from the reception response vectors, and each of the corresponding mobile terminal devices spatially connected based on the extracted reception response vector And calculating a transmission weight vector for controlling the transmission directivity of the antenna.
[0046]
Preferably, in the step of calculating a transmission weight vector, a beam of transmission radio waves is directed to each of the M mobile terminals connected in space, and the transmission radio wave is directed to the other mobile terminal apparatuses. A transmission weight vector that directs null is calculated.
[0047]
Preferably, the number of antenna combinations is selected between M and (N-1).
[0048]
Preferably, the step of selecting the antenna combination selects the combination of antennas in a pre-fixed combination.
[0049]
Preferably, the step of selecting an antenna combination selects an antenna combination based on the calculated reception response vector of each mobile terminal device.
[0050]
Preferably, the step of selecting the antenna combination includes the step of calculating the magnitude of the reception response vector of each of the N antennas corresponding to each of the mobile terminal devices connected in space, and the calculated N Selecting a combination of antennas corresponding to the magnitudes of the reception response vectors corresponding to the number of antennas selected in order from the largest reception response vector of each of the antennas.
[0051]
Preferably, in the step of selecting the antenna combination, the reception response of each of the mobile terminal devices other than the mobile terminal device is received for each of the N antennas corresponding to each of the mobile terminal devices connected in space. The step of calculating the total value of the vector magnitudes, and the magnitudes of the reception response vectors corresponding to the number of antennas to be selected in order from the larger total value of the magnitudes of the reception response vectors of the calculated N antennas. Selecting a combination of antennas corresponding to the sum of.
[0052]
Preferably, the step of selecting the antenna combination includes correlation of reception response vectors between the mobile terminal apparatuses connected in space multiplexing corresponding to each of the predetermined antenna combinations corresponding to the number of antennas to be selected. In accordance with each of the mobile terminal devices that are spatially multiplexed and a step of calculating a value, a combination of antennas that minimizes the sum of correlation values between the mobile terminal device and other mobile terminal devices is selected. Steps.
[0053]
According to still another aspect of the present invention, by controlling the directivity of N (N is an integer of 3 or more) antennas arranged in a discrete manner in real time, M (M is 2 or more and N is greater than N). A transmission directivity control program in a radio base station that allows multiple mobile terminal apparatuses to be spatially multiplexed is a computer that performs adaptive array processing on signals received by N antennas and performs M movements. Extracting received signals from each of the terminal devices, and calculating reception response vectors of M mobile terminal devices connected in space, based on the signals received by the N antennas and the extracted received signals And, for each of the M mobile terminal apparatuses connected in space, a combination of different antennas among the N antennas is selected. And receiving response vectors corresponding to different combinations of antennas selected for each mobile terminal device from the calculated reception response vectors, and performing spatial multiplexing connection based on the extracted reception response vectors Calculating a transmission weight vector for controlling the transmission directivity of the antenna for each of the corresponding mobile terminal apparatuses.
[0054]
Preferably, in the step of calculating a transmission weight vector, a beam of transmission radio waves is directed to each of the M mobile terminals connected in space, and the transmission radio wave is directed to the other mobile terminal apparatuses. A transmission weight vector that directs null is calculated.
[0055]
Preferably, the number of antenna combinations is selected between M and (N-1).
[0056]
Preferably, the step of selecting the antenna combination selects the combination of antennas in a pre-fixed combination.
[0057]
Preferably, the step of selecting an antenna combination selects an antenna combination based on the calculated reception response vector of each mobile terminal apparatus.
[0058]
Preferably, the step of selecting the antenna combination includes the step of calculating the magnitude of the reception response vector of each of the N antennas corresponding to each of the mobile terminal devices connected in space, and the calculated N Selecting a combination of antennas corresponding to the magnitudes of the reception response vectors corresponding to the number of antennas selected in order from the largest reception response vector of each of the antennas.
[0059]
Preferably, in the step of selecting the antenna combination, the reception response of each of the mobile terminal devices other than the mobile terminal device is received for each of the N antennas corresponding to each of the mobile terminal devices connected in space. The step of calculating the total value of the vector magnitudes, and the magnitudes of the reception response vectors corresponding to the number of antennas to be selected in order from the larger total value of the magnitudes of the reception response vectors of the calculated N antennas. Selecting a combination of antennas corresponding to the sum of.
[0060]
Preferably, the step of selecting the antenna combination includes correlation of reception response vectors between the mobile terminal apparatuses connected in space multiplexing corresponding to each of the predetermined antenna combinations corresponding to the number of antennas to be selected. In accordance with each of the mobile terminal devices that are spatially multiplexed and a step of calculating a value, a combination of antennas that minimizes the sum of correlation values between the mobile terminal device and other mobile terminal devices is selected. Steps.
[0061]
Therefore, according to the present invention, in the spatial multiplexing base station, by forming transmission weights with different combinations of antennas and transmitting to each of the terminals to be spatially multiplexed, the spatial multiplexing base station transmits each transmission to each terminal. It is possible to provide a difference in the arrival directions of the desired wave and the interference wave that arrive. For this reason, a terminal equipped with the adaptive array function can sufficiently exhibit the interference removal function, and the communication quality and the area performance can be improved.
[0062]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.
[0063]
FIG. 1 is a conceptual diagram illustrating the basic principle of the present invention. The basic principle of the present invention is to form a transmission weight using a combination of different antennas for each terminal and transmit the difference, so that the arrival directions of the desired wave and the interference wave reaching the terminal have a difference. The purpose is to allow the terminal to exhibit interference removal capability.
[0064]
In the example of FIG. 1, for example, transmission to terminal 1 is performed in a duplex state where two user terminals, terminal 1 and terminal 2, are connected to a spatial multiplexing base station of four antennas ANT1, ANT2, ANT3, and ANT4. In this example, three antennas ANT1, ANT2, and ANT3 are selected as antennas, and three antennas ANT1, ANT2, and ANT4 are selected as transmission antennas for the terminal 2.
[0065]
In the example described below including FIG. 1, the number of antennas constituting the array antenna of the base station is four, but the present invention is not limited to this.
[0066]
That is, in order to use the system according to the present invention, it is generally necessary for M terminals to perform spatial multiplexing connection (M multiplexing) to a base station having N antennas, where N and M are 1 <M <N is an integer that satisfies the magnitude relationship of N. In other words, N is an integer greater than or equal to 3, and M is an integer greater than or equal to 2 and less than N.
[0067]
As described above, in order to select a different antenna combination for each terminal, the maximum number of antennas to be selected is (N−1), while at least M antennas are required for M multiplexing. is there. Therefore, the number of antennas selected for each terminal can be freely selected from M to (N-1).
[0068]
Returning to the example of FIG. 1, in the present invention, a transmission weight is formed by using the arrival direction information included in the reception response vector, for example, by a known method disclosed in Patent Document 1 and Patent Document 2 described above. To do.
[0069]
Since a method for forming a transmission weight from such a reception response vector is disclosed in detail in Patent Document 1 and Patent Document 2 described above, detailed description thereof is omitted here. (Or a reception coefficient vector) represents information related to the amplitude and phase of a signal from each terminal among signal components from the terminal received by the base station.
[0070]
By estimating such a reception response vector for each terminal in the base station, it becomes possible to detect the propagation path characteristics of the radio section from each terminal to the base station, the power value at the time of signal reception, and the like.
[0071]
In particular, in an adaptive array (spatial multiplexing) base station that controls the directivity of transmission / reception of signal radio waves by adjusting the amplitude and phase components of signals transmitted / received by a plurality of antennas constituting an array antenna, each antenna Control of each amplitude and phase component is essentially done by calculating a weight vector based on the estimated received response vector.
[0072]
Note that, as a method of estimating a reception response vector of a signal received from each terminal at the base station, a received signal (IQ signal) received for each antenna of the base station, a remodulation signal of demodulated bit data from the terminal, and A method is used in which a complex multiplication is performed and the result is estimated by performing an ensemble average (time average).
[0073]
In this method, when significant interference is measured, a reception response vector representing information on the arrival direction of the desired user terminal and the interference user terminal is estimated, and based on the estimated reception response vector, the desired user terminal A transmission weight is formed so as to force the beam of the transmission radio wave in the direction and the null of the transmission radio wave in the direction of the interfering user terminal (for example, see the description on pages 16 to 22 of Patent Document 1).
[0074]
As a result, in the same manner as when the reception weight is copied to obtain the transmission weight, the adaptive array base station outputs a transmission signal having directivity targeting the desired user.
[0075]
Such a conventional method of estimating a reception response vector and forming a transmission weight has been performed for all terminals using all the antennas of the base station.
[0076]
In contrast, according to the present invention, transmission is performed using reception response vectors corresponding to only antennas selected to be different for each terminal (not using vector components corresponding to unselected antennas) instead of all antennas. Create weights.
[0077]
With reference to FIG. 1, a process of forming a transmission weight according to the present invention will be schematically described.
[0078]
First, formation of a transmission weight W1 for transmitting a terminal 1 signal targeting the terminal 1 will be described. For terminal 1, antennas ANT1, ANT2, and ANT3 are selected as described above, and the reception response vector from terminal 1 is estimated by these three antennas (block 1a), and from terminal 2 Is estimated (block 1b). These estimated reception response vectors are provided to the transmission weight calculator 1, which forms a transmission weight W1 that directs the beam toward the terminal 1 and the null toward the terminal 2 (block 1c). Transmit from ANT2 and ANT3.
[0079]
Next, the formation of the transmission weight W2 for transmitting the terminal 2 signal targeting the terminal 2 will be described. As described above, the antennas ANT1, ANT2, and ANT4 are selected for the terminal 2, and the reception response vector from the terminal 1 is estimated by these three antennas (block 2a). Is estimated (block 2b). These estimated reception response vectors are provided to the transmission weight calculator 2, which forms a transmission weight W2 that directs a null toward the terminal 1 and a beam toward the terminal 2 (block 2c), and the antenna ANT1, Transmit from ANT2 and ANT4.
[0080]
Note that the estimation of reception response vectors in the blocks 1a, 1b, 2a, and 2b and the calculation of transmission weight formation in the transmission weight calculators 1 and 2 are disclosed in detail in Patent Document 1 and Patent Document 2.
[0081]
As described above, the transmission weight W1 targeted for the terminal 1 and the transmission weight W2 targeted for the terminal 2 are transmitted with different antenna combinations. The direction of arrival will look different.
[0082]
With reference to FIG. 2, the arrival directions of a desired wave and an interference wave viewed from the terminal side when the principle of the present invention of FIG. 1 is applied will be described. The various arrows used in FIG. 2 are the same as those used in FIG.
[0083]
Even if the transmission signal beam and null direction control cannot be performed satisfactorily due to the movement of the terminal or the like, the terminal 1 signal (S1) which is a desired wave and the terminal which is an interference wave are viewed from the terminal 1 Since the two signals (S2) are transmitted from different antenna combinations, the two signals (S2) appear to come from different directions. From the viewpoint of the terminal 2, the terminal 2 signal (S2) that is a desired wave and a terminal that is an interference wave One signal (S1) also appears to come from different directions.
[0084]
As described above, in the spatial multiplexing base station according to the present invention, transmission is performed not to all the antennas of the array antenna but to different combinations of antennas for all of a plurality of terminals that are spatially multiplexed to the base station. Therefore, even when the transmission directivity control at the base station cannot be performed satisfactorily due to various causes, it seems that the desired wave and the interference wave come from different directions at each terminal, and the terminal having the adaptive array function If there is, it is possible to remove the interference wave and extract only the desired wave.
[0085]
Next, an antenna selection method for realizing the basic principle of the present invention will be described in detail.
[0086]
[Embodiment 1]
FIG. 3 is a diagram showing a table of antenna selection modes according to the first embodiment of the present invention.
[0087]
According to the first embodiment, an antenna combination for each terminal is selected in a combination fixed in advance according to the multiplicity.
[0088]
The table in FIG. 3 exemplifies the applicability of the present invention for each multiplicity in a four-antenna base station and combinations of antennas fixed in advance when applicable.
[0089]
First, in the case of double multiplexing in which terminal 1 and terminal 2 are connected, two or three antennas corresponding to the above-described range of M to (N-1) are selected. Note that if the number of antennas (two in this case) is selected, the difference between the arrival directions of the desired wave and the interference wave can be increased, but the accuracy of forming the transmission directivity is inferior. For this reason, basically, it is desirable to select the number of antennas (three in this case) corresponding to (N-1).
[0090]
First, when two transmission antennas are selected, for example, ANT1 and ANT2 are determined in advance as antennas for forming and transmitting a transmission weight for the terminal 1, and for forming and transmitting a transmission weight for the terminal 2. ANT3 and ANT4 are determined in advance as antennas.
[0091]
On the other hand, when three transmission antennas are selected, for example, ANT1, ANT2, and ANT3 are determined in advance as antennas for forming and transmitting a transmission weight for the terminal 1, and a transmission weight for the terminal 2 is formed and transmitted. ANT2, ANT3, and ANT4 are determined in advance as antennas for this purpose.
[0092]
Next, in the case of triple multiplexing in which terminal 1, terminal 2, and terminal 3 are connected, the number of antennas corresponding to the above-described range of M to (N-1) is only three. Therefore, when the number of antennas is two, the present invention cannot be applied.
[0093]
When three transmission antennas are selected, for example, ANT1, ANT2, and ANT3 are determined in advance as antennas for forming and transmitting a transmission weight for the terminal 1, and a transmission weight for the terminal 2 is formed and transmitted. ANT2, ANT3, and ANT4 are determined in advance as antennas, and ANT1, ANT3, and ANT4 are determined in advance as antennas for forming and transmitting transmission weights for the terminal 3.
[0094]
Next, in the case of 4 multiplexing in which terminal 1, terminal 2, terminal 3 and terminal 4 are connected, there is no number of antennas corresponding to the range of M to (N-1) described above. The application of this invention is not possible.
[0095]
Such Embodiment 1 has the advantage that the process for antenna selection is simple.
[0096]
[Embodiment 2]
FIG. 4 is a diagram showing a table for explaining the principle of antenna selection according to the second embodiment of the present invention.
[0097]
According to the second embodiment, the antenna combination for each terminal is selected according to the magnitude of the reception response vector according to the reception response vector calculated for each terminal.
[0098]
The example of FIG. 4 shows a case of 3 multiplexing with 4 antennas. In this case, the number of antennas selected is three as described above.
[0099]
Referring to FIG. 4, the magnitudes of the components corresponding to the antennas ANT1, ANT2, ANT3, and ANT4 of the reception response vectors of the signals received from the terminal 1 by the four antennas are 1.2, 0.5, 0.8 and 1.0.
[0100]
Next, the magnitudes of the components corresponding to the antennas ANT1, ANT2, ANT3, and ANT4 of the reception response vectors of the signals received from the terminal 2 by the four antennas are 0.7, 0.8, 0.3, 0.5.
[0101]
Next, the magnitudes of the components corresponding to the antennas ANT1, ANT2, ANT3, and ANT4 of the reception response vectors of the signals received from the terminal 3 by the four antennas are 0.8, 0.9, 1.3, 1.2.
[0102]
In the second embodiment, in order to direct a beam more accurately to a desired user terminal, a combination of three antennas is determined for each terminal in order from the largest reception response vector.
[0103]
In FIG. 4, for the terminal 1, ANT1, ANT3, and ANT4 whose reception response vectors are 1.2, 0.8, and 1.0 are selected.
[0104]
For the terminal 2, ANT1, ANT2, and ANT4 whose reception response vectors are 0.7, 0.8, and 0.5 are selected.
[0105]
For the terminal 3, ANT2, ANT3, and ANT4 whose reception response vectors are 0.9, 1.3, and 1.2 are selected.
[0106]
Thus, by forming and transmitting a transmission weight using a set of antennas selected for each terminal, it is possible to form a transmission weight in which a beam is directed more accurately to a desired user terminal, and a corresponding adaptive array Interference cancellation capability at the terminal can be demonstrated more cooperatively.
[0107]
[Embodiment 3]
FIG. 5 shows a table for explaining the principle of antenna selection according to the third embodiment of the present invention.
[0108]
According to the third embodiment, based on the reception response vector (FIG. 4) calculated for each terminal, the total value of the reception response vectors of terminals (interference terminals) other than the terminal (desired terminal) Is calculated for each antenna, and an antenna combination for each terminal is selected according to the size of the total value.
[0109]
The example of FIG. 5 shows a case of three multiplexing with four antennas. In this case, the number of antennas selected is three as described above.
[0110]
With reference to the table of reception response vector magnitudes in FIG. 4, when the terminal 1 is a desired terminal, the total value of the magnitudes of the reception response vectors received by the antenna ANT1 from the terminal 2 and the terminal 3 as interference terminals is 0.7 + 0.8 = 1.5. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT2 from the terminals 2 and 3 serving as the interference terminals is 0.8 + 0.9 = 1.7. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT3 from the terminals 2 and 3 serving as interference terminals is 0.3 + 1.3 = 1.6. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT4 from the terminals 2 and 3 serving as the interference terminals is 0.5 + 1.2 = 1.7.
[0111]
Next, when the terminal 2 is a desired terminal, the total value of the reception response vectors received by the antenna ANT1 from the terminal 1 and the terminal 3 serving as interference terminals is 1.2 + 0.8 = 2.0. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT2 from the terminal 1 and the terminal 3 serving as interference terminals is 0.5 + 0.9 = 1.4. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT3 from the terminal 1 and the terminal 3 serving as interference terminals is 0.8 + 1.3 = 2.1. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT4 from the terminal 1 and the terminal 3 serving as interference terminals is 1.0 + 1.2 = 2.2.
[0112]
Next, when the terminal 3 is a desired terminal, the total value of the reception response vectors received by the antenna ANT1 from the terminal 1 and the terminal 2 serving as interference terminals is 1.2 + 0.7 = 1.9. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT2 from the terminal 1 and the terminal 2 that are interfering terminals is 0.5 + 0.8 = 1.3. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT3 from the terminal 1 and the terminal 2 that are interfering terminals is 0.8 + 0.3 = 1.1. Similarly, the total value of the magnitudes of the reception response vectors received by the antenna ANT4 from the terminal 1 and the terminal 2 serving as interference terminals is 1.0 + 0.5 = 1.5.
[0113]
The table in FIG. 5 summarizes the above results as the relationship between each terminal (desired terminal) and the total value of the reception response vectors of the interference terminals for each antenna.
[0114]
In this third embodiment, in order to direct null more accurately with respect to the interfering terminal, for each terminal (desired terminal), there are three in order from the largest total value of the magnitude of the reception response vector of the interfering terminal. Determine the antenna combination.
[0115]
In FIG. 5, for the terminal 1, ANT2, ANT3, and ANT4 whose interference terminal reception response vector magnitude total values are 1.7, 1.6, and 1.7 are selected.
[0116]
For the terminal 2, ANT1, ANT3, and ANT4 having a total size of interference terminal reception response vectors of 2.0, 2.1, and 2.2 are selected.
[0117]
For the terminal 3, ANT1, ANT2, and ANT4 having a total value of interference terminal reception response vectors of 1.9, 1.3, and 1.5 are selected.
[0118]
Thus, by forming and transmitting a transmission weight using a set of antennas selected for each terminal, it is possible to form a transmission weight in which a null is more accurately directed to an interfering terminal, and a corresponding adaptive array terminal This makes it possible to exert more powerful interference removal capability.
[0119]
[Embodiment 4]
6 and 7 are diagrams showing tables for explaining the principle of antenna selection according to the fourth embodiment of the present invention.
[0120]
According to the fourth embodiment, different antenna combinations are determined in advance, the reception response vector of each terminal is calculated for each combination, and the correlation value of the reception response vectors between the terminals is calculated. Based on the calculated reception response vector correlation value, the total value of the reception response vector correlation values of the terminal (desired terminal) and other terminals (interference terminals) is calculated for each antenna combination. Then, the antenna combination having the minimum total value is selected.
[0121]
The example of FIG. 6 and FIG. 7 shows the case of 3 multiplexing with 4 antennas. In this case, the number of antennas selected is three as described above.
[0122]
Referring to FIG. 6, the first combination of ANT1, ANT2, and ANT3, the second combination of ANT1, ANT2, and ANT4, the third combination of ANT1, ANT3, and ANT4, and the fourth combination of ANT2, ANT3, and ANT4 Four combinations are predetermined.
[0123]
Here, calculation of the correlation value of the reception response vector will be described. When there are reception response vectors h1 and h2, the correlation value is expressed by the following equation.
[0124]
Correlation value = (h1 · h2) / (| h1 | · | h2 |), where (h1 · h2) represents an inner product and | h1 | represents an absolute value.
[0125]
Referring to FIG. 6, for the first combination of antennas, the correlation value of the reception response vector between terminal 1 and terminal 2 is 0.4, and the correlation value of the reception response vector between terminal 1 and terminal 3 is 0.8.
[0126]
Next, regarding the second combination of antennas, the correlation value of the reception response vector between terminal 1 and terminal 2 is 0.5, and the correlation value of the reception response vector between terminal 1 and terminal 3 is 0.9. is there.
[0127]
Next, regarding the third combination of antennas, the correlation value of the reception response vector between the terminal 1 and the terminal 2 is 0.8, and the correlation value of the reception response vector between the terminal 1 and the terminal 3 is 0.3. is there.
[0128]
Next, for the fourth combination of antennas, the correlation value of the reception response vector between terminal 1 and terminal 2 is 0.2, and the correlation value of the reception response vector between terminal 1 and terminal 3 is 0.2. is there.
[0129]
Furthermore, with reference to FIG. 6, the correlation value of the reception response vector between terminal 2 and terminal 3 is 0.2 for the first combination of antennas.
[0130]
Next, for the second combination of antennas, the correlation value of the reception response vector between terminal 2 and terminal 3 is 0.6.
[0131]
Next, for the third combination of antennas, the correlation value of the reception response vector between terminal 2 and terminal 3 is 0.3.
[0132]
Next, regarding the fourth combination of antennas, the correlation value of the reception response vector between terminal 2 and terminal 3 is 0.5.
[0133]
Here, when the terminal 1 is a desired terminal, the sum of the correlation values of the terminal 1 and the terminals 2 and 3 corresponding to the interference terminals is 0. 0 for the first combination of antennas. 4 + 0.8 = 1.2, for the second combination of antennas, 0.5 + 0.9 = 1.4, and for the third combination of antennas, 0.8 + 0.3 = 1.1 For the fourth combination, 0.2 + 0.2 = 0.4.
[0134]
Next, when the terminal 2 is a desired terminal, the sum of the correlation values of the terminal 2 and the terminals 1 and 3 corresponding to the interference terminals is 0. 0 for the first combination of antennas. 4 + 0.2 = 0.6, for the second combination of antennas, 0.5 + 0.6 = 1.1, and for the third combination of antennas, 0.8 + 0.3 = 1.1 For the fourth combination, 0.2 + 0.5 = 0.7.
[0135]
Next, when the terminal 3 is a desired terminal, the sum of correlation values between the terminal 3 and the terminals 1 and 2 corresponding to the interfering terminals is 0. 0 with respect to the first combination of antennas. 8 + 0.2 = 1.0, 0.9 + 0.6 = 1.5 for the second antenna combination, and 0.3 + 0.3 = 0.6 for the third antenna combination. For the fourth combination, 0.2 + 0.5 = 0.7.
[0136]
The table of FIG. 7 summarizes the above results as the relationship between each terminal (desired terminal) and the total value of the reception response vector correlation values of the interference terminal for each antenna combination.
[0137]
In this fourth embodiment, in order to direct the beam more accurately to the desired terminal and more accurately direct the null to the interfering terminal, for each terminal (desired terminal), the received response vector correlation value with the interfering terminal The combination of antennas with the smallest sum of values is selected.
[0138]
In FIG. 7, for the terminal 1, a combination of ANT2, ANT3, and ANT4 having the minimum total value of the reception response vector correlation values with the interference terminal of 0.4 is selected.
[0139]
For the terminal 2, a combination of ANT1, ANT2, and ANT3 having a minimum total value of the reception response vector correlation values with the interference terminal of 0.6 is selected.
[0140]
For the terminal 3, a combination of ANT1, ANT3, and ANT4 having a total sum of the reception response vector correlation values with the interference terminal of 0.6 is selected.
[0141]
In this way, by forming and transmitting a transmission weight using a set of antennas selected for each terminal, a transmission weight in which a beam is more accurately directed to a desired terminal and a null is more accurately directed to an interfering terminal. The interference canceling capability of the corresponding adaptive array terminal can be exhibited more cooperatively.
[0142]
Next, FIG. 8 is a functional block diagram of a spatial multiplexing base station for realizing Embodiments 1 to 4 of the present invention. This functional block diagram corresponds to double multiplexing in which a terminal 1 and a terminal 2 are connected in a four-antenna spatial multiplexing base station.
[0143]
Referring to FIG. 8, signals received by antennas ANT1, ANT2, ANT3, and ANT4 are given to reception processing apparatus 100, and received signal 1 from terminal 1 and received signal 2 from terminal 2 are respectively obtained by adaptive array processing. Extracted.
[0144]
The transmission signal 1 for the terminal 1 and the transmission signal 2 for the terminal 2 are given to the transmission processing apparatus 200, and after the transmission directivity is controlled, they are combined and transmitted by the antennas ANT1, ANT2, ANT3, and ANT4.
[0145]
Connections between the antennas ANT1, ANT2, ANT3, and ANT4 and the reception processing device 100 and the transmission processing device 200 are selectively switched by switches SW1, SW2, SW3, and SW4.
[0146]
First, the operation at the time of reception will be described. Signals received by the antennas ANT1, ANT2, ANT3, and ANT4 enter the reception processing device 100 via the switches SW1, SW2, SW3, and SW4, and the received signal 1 from the terminal 1 For extraction, it is given to one input of each of the multipliers 11a, 12a, 13a, and 14a, and also given to the reception weight vector calculator 16a and the reception response vector calculator 18a.
[0147]
From the received weight vector calculator 16a, weights wrx11, wrx21, wrx31, wrx41 for the received signals at the respective antennas are outputted and given to the other inputs of the multipliers 11a, 12a, 13a, 14a.
[0148]
Signals received by antennas ANT1, ANT2, ANT3, and ANT4 and corresponding weights wrx11, wrx21, wrx31, and wrx41 are multiplied by multipliers 11a, 12a, 13a, and 14a, respectively, and the result is added by adder 15a. Is done.
[0149]
The array output from the adder 15a is output as a reception signal 1, and is given to the reception weight vector calculator 16a and the reception response vector calculator 18a. The reception weight vector calculator 16a is given a known reference signal from the memory 17a.
[0150]
The reception weight vector calculator 16a generates the reception weight vectors wrx11, wrx21, wrx31, and wrx41 in real time so as to reduce the square of the error between the array output from the adder 15a and the known reference signal stored in the memory 17a. To converge. Thereby, the reception directivity from the specific terminal 1 can be converged, and the reception signal 1 from the desired terminal 1 can be extracted.
[0151]
On the other hand, the signal received by the antennas ANT1, ANT2, ANT3, and ANT4 and entering the reception processing device 100 via the switches SW1, SW2, SW3, and SW4 is used as a multiplier 11b for extracting the received signal 2 from the terminal 2. , 12b, 13b, and 14b, and is provided to the reception weight vector calculator 16b and the reception response vector calculator 18b.
[0152]
From the reception weight vector calculator 16b, weights wrx12, wrx22, wrx32, wrx42 for the reception signals at the respective antennas are outputted and given to the other inputs of the multipliers 11b, 12b, 13b, 14b.
[0153]
Signals received by antennas ANT1, ANT2, ANT3, and ANT4 and corresponding weights wrx12, wrx22, wrx32, and wrx42 are multiplied by multipliers 11b, 12b, 13b, and 14b, respectively, and the result is added by adder 15b. Is done.
[0154]
The array output from the adder 15b is output as the received signal 2, and is given to the received weight vector calculator 16b and the received response vector calculator 18b. The reception weight vector calculator 16b is given a known reference signal from the memory 17b.
[0155]
The received weight vector calculator 16b converts the received weight vectors wrx12, wrx22, wrx32, wrx42 in real time so as to reduce the square of the error between the array output from the adder 15b and the known reference signal stored in the memory 17b. To converge. Thereby, the reception directivity from the specific terminal 2 can be converged, and the reception signal 2 from the desired terminal 2 can be extracted.
[0156]
Note that the adaptive array algorithm used in the reception weight vector calculators 16a and 16b is well known as disclosed in Non-Patent Documents 1 and 2, and will not be described here.
[0157]
On the other hand, the reception response vector calculator 18a calculates the reception response vector of the terminal 1 according to the signals received by the antennas ANT1, ANT2, ANT3, and ANT4 and the array output from the adder 15a, and the transmission processing device 200 To the antenna selector 30.
[0158]
Further, the reception response vector calculator 18b calculates the reception response vector of the terminal 2 in accordance with the signals received by the antennas ANT1, ANT2, ANT3, and ANT4 and the array output from the adder 15b. To the antenna selector 30.
[0159]
The algorithms used in the reception response vector computers 18a and 18b are well known as disclosed in Patent Documents 1 and 2, and will not be described here.
[0160]
The antenna selector 30 determines different antenna combinations for each terminal used for transmission weight formation and transmission by any of the antenna selection methods described in the first to fourth embodiments. The processing operation of the antenna selector 30 will be described later.
[0161]
Of the reception response vectors corresponding to the terminal 1 calculated by the reception response vector calculator 18a, a reception response vector composed of components corresponding to the antenna combination corresponding to the terminal 1 selected by the antenna selector 30 (for the unselected antenna). The corresponding component is replaced with 0 or notified to the transmission weight vector calculator that it will not be used) from the antenna selector 30 to the transmission weight vector calculator 26a.
[0162]
On the other hand, among the reception response vectors corresponding to the terminal 2 calculated by the reception response vector calculator 18b, a reception response vector (non-selected) composed of components corresponding to the antenna combination corresponding to the terminal 2 selected by the antenna selector 30. The component corresponding to the antenna is replaced with 0 or notified to the transmission weight vector calculator that it is not used), and is sent from the antenna selector 30 to the transmission weight vector calculator 26b.
[0163]
The transmission weight vector calculator 26a calculates transmission weight vectors wtx11, wtx21, wtx31, and wtx41 based on the reception response vector of the antenna combination corresponding to the terminal 1, and sets it in the transmission weight vector setting unit 25a.
[0164]
A transmission signal 1 for the terminal 1 is input to one input of each of the multipliers 21a, 22a, 23a, and 24a, and transmission weight vectors wtx11, wtx21, wtx31, and wtx41 from the transmission weight vector setting unit 25a are input to the other input. Entered.
[0165]
The transmission weight vector calculator 26b calculates transmission weight vectors wtx12, wtx22, wtx32, and wtx42 based on the reception response vector of the antenna combination corresponding to the terminal 2, and sets it in the transmission weight vector setting unit 25b.
[0166]
A transmission signal 2 for the terminal 2 is input to one input of each of the multipliers 21b, 22b, 23b, and 24b, and transmission weight vectors wtx12, wtx22, wtx32, and wtx42 from the transmission weight vector setting unit 25b are input to the other input. Entered.
[0167]
The outputs of the multipliers 21a, 22a, 23a, and 24a and the outputs of the multipliers 21b, 22b, 23b, and 24b are combined, and the antennas ANT1, ANT2, ANT3, and ANT4 via the switches SW1, SW2, SW3, and SW4. Is output from.
[0168]
The algorithms used in the transmission weight vector calculators 26a and 26b are well known as disclosed in Patent Documents 1 and 2, and will not be described here.
[0169]
As described above, in the spatial multiplexing base station of FIG. 8, for each of the terminals 1 and 2, transmission weight vectors are formed by different antenna combinations selected by the antenna selector 30. It is possible to provide a difference in the arrival directions of the desired wave and the interference wave seen.
[0170]
The antenna selection method according to the embodiment of the present invention executed by the antenna selector 30 of the above-described functional block diagram is actually performed by a digital signal processor (DSP) (not shown) according to the flow shown in FIGS. It is executed by software according to the figure. The DSP (not shown) reads a program including the steps of the flowcharts shown in FIGS. 9 to 11 from a memory (not shown) and executes the program. This program can be installed externally.
[0171]
The antenna selection algorithm according to the second to fourth embodiments of the present invention will be described below with reference to FIGS. Since the combination of antennas is fixed in the first embodiment, a flowchart for antenna selection is omitted.
[0172]
FIG. 9 shows the antenna selection algorithm according to the second embodiment described with reference to FIG.
[0173]
Referring to FIG. 9, in step S1, the multiplicity is set to M and the number n of the user terminal as the desired terminal is set to 1, and the process is started. Note that all antennas (four in this example) that constitute the array antenna of the base station can be candidates for selection.
[0174]
In step S2, it is determined whether or not the user terminal number n = 1 is equal to or less than the multiplicity M. If it is determined that the user terminal number n = 1 is equal to or less than the multiplicity M, the process proceeds to step S3, and as shown in the table of FIG. 4, the magnitude of the reception response vector of each antenna of the desired terminal n = 1. The antenna with the smallest size is selected.
[0175]
Next, in step S4, the antenna having the smallest reception response vector selected in step S3 is excluded from the antenna selection candidates.
[0176]
In step S5, the remaining three antennas other than the antennas excluded in step S4 are determined as combinations of transmission antennas for terminal n = 1.
[0177]
Next, in step S6, the user terminal number n is incremented by 1, and the process returns to step S2. The processes in steps S3 to S6 are executed until the user terminal number n becomes equal to the multiplicity M. If it is determined in step S2 that the user terminal number n has exceeded the multiplicity M, the process is terminated.
[0178]
FIG. 10 shows an antenna selection algorithm according to the third embodiment described with reference to FIG.
[0179]
Referring to FIG. 10, in step S11, the multiplicity is set to M and the number n of the user terminal as the desired terminal is set to 1, and the process is started. Note that all antennas (four in this example) that constitute the array antenna of the base station can be candidates for selection.
[0180]
In step S12, it is determined whether or not the user terminal number n = 1 is equal to or less than the multiplicity M. If it is determined that the user terminal number n = 1 is equal to or less than the multiplicity M, the process proceeds to step S13, and as shown in the table of FIG. 5, the reception response of the interference terminal other than the terminal n = 1 for each antenna. Calculate the total vector magnitude.
[0181]
Next, in step S14, the total value of the interference terminal reception response vectors for each antenna of the desired terminal n = 1 is compared from the table of FIG. 5 created in step S13, and the total value is the minimum. Select the antenna.
[0182]
Next, in step S15, the antenna having the smallest total value of the interference terminal reception response vectors selected in step S14 is excluded from the antenna selection candidates.
[0183]
Next, in step S16, the remaining three antennas other than the antennas excluded in step S15 are determined as combinations of transmission antennas for terminal n = 1.
[0184]
Next, in step S17, the user terminal number n is incremented by 1, and the process returns to step S12. The processes in steps S13 to S17 are executed until the user terminal number n becomes equal to the multiplicity M. If it is determined in step S12 that the user terminal number n has exceeded the multiplicity M, the process ends.
[0185]
FIG. 11 shows the antenna selection algorithm of the fourth embodiment described with reference to FIGS. 6 and 7.
[0186]
Referring to FIG. 11, in step S21, the multiplicity is set to M and the number n of the user terminal as the desired terminal is set to 1, and the process is started. Note that all antennas (four in this example) that constitute the array antenna of the base station can be candidates for selection.
[0187]
In step S22, it is determined whether or not the user terminal number n = 1 is equal to or less than the multiplicity M. If it is determined that the user terminal number n = 1 is equal to or less than the multiplicity M, the process proceeds to step S23, and as shown in the table of FIG. calculate.
[0188]
Next, in step S24, as shown in the table of FIG. 7, the total value of the reception response vector correlation values between the desired terminal n = 1 and the other interfering terminals is calculated. Then, the total value of the interference terminal reception response vector correlation values for each antenna combination of the desired terminal n = 1 is compared, and the antenna combination having the minimum total value is selected.
[0189]
Next, in step S25, the combination of the antennas selected in step S24 is determined as the transmission antenna combination for terminal n = 1.
[0190]
Next, in step S26, the user terminal number n is incremented by 1, and the process returns to step S22. The processes in steps S23 to S26 are executed until the user terminal number n becomes equal to the multiplicity M. If it is determined in step S22 that the user terminal number n has exceeded the multiplicity M, the process ends.
[0191]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0192]
【The invention's effect】
As described above, according to the present invention, in a spatial multiplexing base station, by forming a transmission weight with a combination of different antennas and transmitting to each of the terminals to be spatially multiplexed, It is possible to provide a difference in the arrival directions of the desired wave and the interference wave that reach each terminal. For this reason, even if the transmission directivity control at the base station cannot be performed satisfactorily due to movement of the terminal or the like, the terminal having the adaptive array function can sufficiently exhibit the interference removal function, and the communication Quality and area performance can be improved.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating the basic principle of the present invention.
FIG. 2 is a diagram schematically illustrating an antenna usage pattern and a signal arrival direction of a spatial multiplexing base station according to the basic principle of the present invention.
FIG. 3 is a diagram showing a table of antenna selection modes according to the first embodiment of the present invention.
FIG. 4 is a diagram showing a table for explaining the principle of antenna selection according to Embodiment 2 of the present invention;
FIG. 5 is a diagram showing a table for explaining the principle of antenna selection according to Embodiment 3 of the present invention;
FIG. 6 is a diagram showing a table for explaining the principle of antenna selection according to Embodiment 4 of the present invention;
FIG. 7 is a diagram showing a table for explaining the principle of antenna selection according to Embodiment 4 of the present invention;
FIG. 8 is a functional block diagram of a spatial multiplexing base station for realizing Embodiments 1 to 4 of the present invention.
FIG. 9 is a flowchart showing processing of Embodiment 2 of the present invention.
FIG. 10 is a flowchart showing processing of Embodiment 3 of the present invention.
FIG. 11 is a flowchart showing processing of Embodiment 4 of the present invention.
FIG. 12 is a diagram showing a table that summarizes how each terminal signal works in each terminal.
FIG. 13 is a diagram schematically illustrating an antenna usage pattern and a signal arrival direction of a conventional spatial multiplexing base station.
[Explanation of symbols]
1, 2 transmission weight calculator, 11a, 12a, 13a, 14a, 11b, 12b, 13b, 14b, 21a, 22a, 23a, 24a, 21b, 22b, 23b, 24b multiplier, 15a, 15b adder, 16a, 16b Reception weight vector calculator, 17a, 17b memory, 18a, 18b reception response vector calculator, 25a, 25b transmission weight vector setting unit, 26a, 26b transmission weight vector calculator, 30 antenna selector, 100 reception processing device, 200 transmission processing device, ANT1, ANT2, ANT3, ANT4 antenna, SW1, SW2, SW3, SW4 switch.

Claims (24)

By controlling the directivity of N (N is an integer greater than or equal to 3) antennas arranged in a discrete manner in real time, M (M is an integer greater than or equal to 2 and smaller than N) mobile terminal devices can be spatially multiplexed. A wireless base device that allows connection,
Adaptive array processing means for performing adaptive array processing on signals received by the N antennas to extract received signals from each of the M mobile terminal devices;
A reception response vector calculation means for calculating a reception response vector of each of the M mobile terminal apparatuses spatially multiplexed based on a signal received by the N antennas and the extracted reception signal;
Antenna combination selecting means for selecting and assigning different combinations of the N antennas to each of the M mobile terminal apparatuses spatially connected;
Of the calculated reception response vectors, reception response vectors corresponding to different combinations of antennas selected for each mobile terminal apparatus are extracted, and the spatial multiplexing connection is performed based on the extracted reception response vectors. A radio base apparatus comprising: a transmission weight vector calculating means for calculating a transmission weight vector for controlling the transmission directivity of the antenna for each corresponding mobile terminal apparatus. The transmission weight vector calculation means directs a beam of transmission radio waves to each of the M mobile terminals connected in space, directs a beam of transmission radio waves to the mobile terminal apparatus, and directs nulls of transmission radio waves to other mobile terminal apparatuses. The radio base apparatus according to claim 1, wherein such a transmission weight vector is calculated. The radio base apparatus according to claim 1 or 2, wherein the combination of antennas is selected by a number between M and (N-1). The radio base apparatus according to claim 3, wherein the antenna combination selection unit selects the combination of the antennas in a fixed combination. The radio base apparatus according to claim 3, wherein the antenna combination selection unit selects the antenna combination based on the calculated reception response vector of each mobile terminal apparatus. The antenna combination selection means includes
Means for calculating the magnitude of the reception response vector of each of the N antennas corresponding to each of the mobile terminal devices connected in space multiplexing;
Means for selecting antenna combinations corresponding to the sizes of reception response vectors corresponding to the number of selected antennas in order from the largest reception response vector of each of the calculated N antennas. Item 6. The wireless base device according to Item 5. The antenna combination selection means includes
Corresponding to each of the mobile terminal devices connected in space multiplexing, for each of the N antennas, the total value of the magnitudes of reception response vectors of mobile terminal devices other than the mobile terminal device is calculated. Means for calculating;
The combination of antennas corresponding to the total value of the reception response vectors corresponding to the number of selected antennas is selected in descending order from the calculated total value of the reception response vectors of the N antennas. The radio base apparatus according to claim 5, further comprising: means. The antenna combination selection means includes
Means for calculating a correlation value of reception response vectors between the mobile terminal apparatuses connected in space, corresponding to each of predetermined antenna combinations corresponding to the number of antennas selected;
Means for selecting a combination of antennas corresponding to each of the mobile terminal devices that are spatially connected to each other so that the sum of correlation values between the mobile terminal device and another mobile terminal device is minimized. The radio base apparatus according to claim 5. By controlling the directivity of N (N is an integer greater than or equal to 3) antennas arranged in a discrete manner in real time, M (M is an integer greater than or equal to 2 and smaller than N) mobile terminal devices can be spatially multiplexed. A transmission directivity control method in a radio base device that allows connection,
Applying adaptive array processing to signals received by the N antennas to extract received signals from each of the M mobile terminal devices;
Calculating reception response vectors of each of the M mobile terminal apparatuses spatially multiplexed based on signals received by the N antennas and the extracted received signals;
Selecting and assigning different combinations of antennas among the N antennas to each of the M mobile terminal apparatuses spatially connected;
Of the calculated reception response vectors, reception response vectors corresponding to different combinations of antennas selected for each mobile terminal apparatus are extracted, and the spatial multiplexing connection is performed based on the extracted reception response vectors. Calculating a transmission weight vector for controlling the transmission directivity of the antenna for each corresponding mobile terminal apparatus. The step of calculating the transmission weight vector includes directing a beam of transmission radio waves to each of the M mobile terminals connected in space and directing a beam of transmission radio waves to the mobile terminal apparatus, and nulling the transmission radio waves to other mobile terminal apparatuses. The transmission directivity control method according to claim 9, wherein a transmission weight vector is calculated so that The transmission directivity control method according to claim 9 or 10, wherein the combination of the antennas is selected by a number between M and (N-1). The transmission directivity control method according to claim 11, wherein the step of selecting the antenna combination selects the combination of the antennas in a combination fixed in advance. 12. The transmission directivity control method according to claim 11, wherein the step of selecting the antenna combination selects the combination of antennas based on the calculated reception response vectors of the mobile terminal devices. Selecting the antenna combination comprises:
Calculating a magnitude of a reception response vector of each of the N antennas corresponding to each of the mobile terminal apparatuses that are spatially connected;
Selecting a combination of antennas corresponding to the magnitudes of reception response vectors corresponding to the number of selected antennas in order from the largest reception response vector of each of the calculated N antennas. Item 14. A transmission directivity control method according to Item 13. Selecting the antenna combination comprises:
Corresponding to each of the mobile terminal devices connected in space multiplexing, for each of the N antennas, the total value of the magnitudes of reception response vectors of mobile terminal devices other than the mobile terminal device is calculated. A calculating step;
The combination of antennas corresponding to the total value of the reception response vectors corresponding to the number of selected antennas is selected in descending order from the calculated total value of the reception response vectors of the N antennas. The transmission directivity control method according to claim 13, comprising: steps. Selecting the antenna combination comprises:
Corresponding to each of the predetermined combinations of antennas for the number of antennas to be selected, calculating a correlation value of reception response vectors between the mobile terminal apparatuses that are spatially connected,
Selecting a combination of antennas that minimizes the sum of correlation values between the mobile terminal device and another mobile terminal device, corresponding to each of the mobile terminal devices that are spatially connected. The transmission directivity control method according to claim 13. By controlling the directivity of N (N is an integer greater than or equal to 3) antennas arranged in a discrete manner in real time, M (M is an integer greater than or equal to 2 and smaller than N) mobile terminal devices can be spatially multiplexed. A transmission directivity control program in a radio base device that allows connection, and
Applying adaptive array processing to signals received by the N antennas to extract received signals from each of the M mobile terminal devices;
Calculating reception response vectors of each of the M mobile terminal apparatuses spatially multiplexed based on signals received by the N antennas and the extracted received signals;
Selecting and assigning different combinations of antennas among the N antennas to each of the M mobile terminal apparatuses spatially connected;
Of the calculated reception response vectors, reception response vectors corresponding to different combinations of antennas selected for each mobile terminal apparatus are extracted, and the spatial multiplexing connection is performed based on the extracted reception response vectors. A transmission directivity control program for causing a corresponding mobile terminal device to execute a transmission weight vector for controlling the transmission directivity of the antenna. The step of calculating the transmission weight vector includes directing a beam of transmission radio waves to each of the M mobile terminals connected in space and directing a beam of transmission radio waves to the mobile terminal apparatus, and nulling the transmission radio waves to other mobile terminal apparatuses. The transmission directivity control program according to claim 17, wherein the transmission weight vector is calculated such that The transmission directivity control program according to claim 17 or 18, wherein the combination of antennas is selected by a number between M and (N-1). The transmission directivity control program according to claim 19, wherein the step of selecting the antenna combination selects the combination of the antennas in a combination that is fixed in advance. The transmission directivity control program according to claim 19, wherein the step of selecting the antenna combination selects the antenna combination based on the calculated reception response vector of each mobile terminal apparatus. Selecting the antenna combination comprises:
Calculating a magnitude of a reception response vector of each of the N antennas corresponding to each of the mobile terminal apparatuses that are spatially connected;
Selecting a combination of antennas corresponding to the magnitudes of reception response vectors corresponding to the number of selected antennas in order from the largest reception response vector of each of the calculated N antennas. Item 22. The transmission directivity control program according to Item 21. Selecting the antenna combination comprises:
Corresponding to each of the mobile terminal devices connected in space multiplexing, for each of the N antennas, the total value of the magnitudes of reception response vectors of mobile terminal devices other than the mobile terminal device is calculated. A calculating step;
The combination of antennas corresponding to the total value of the reception response vectors corresponding to the number of selected antennas is selected in descending order from the calculated total value of the reception response vectors of the N antennas. The transmission directivity control program according to claim 21, comprising a step. Selecting the antenna combination comprises:
Corresponding to each of the predetermined combinations of antennas for the number of antennas to be selected, calculating a correlation value of reception response vectors between the mobile terminal apparatuses that are spatially connected,
Selecting a combination of antennas that minimizes the sum of correlation values between the mobile terminal device and another mobile terminal device, corresponding to each of the mobile terminal devices that are spatially connected. The transmission directivity control program according to claim 21.

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