JP2002064321A - Wave polarization control system, terminal and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase system capacity by recognizing the deteriorated communication quality in mobile communication. SOLUTION: A mobile terminal is configured to perform transmitting/ receiving with both a vertically polarized wave and a horizontally polarized wave, a base station is provided with a vertically polarized wave array antenna 60 and a horizontally polarized wave array antenna 61, and transmission is performed to a new terminal with the vertically polarized wave under adaptive control. Then, an output SINR corresponding to the transmission wave of each of existing terminals at that time is measured, a minimum value SINR(V) thereof is found, and transmission is performed to the new terminal with the horizontally polarized wave. Then, an output SINR corresponding to the transmission wave of each of existing terminals at that time is measured, a minimum value SINR(H) thereof is found, and a polarized wave corresponding to greater one of SINR(V) and SINR(H) is assigned as a transmitting/receiving radio wave for the new terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an environment in which an interference wave is present, by removing the interference wave,
The present invention relates to a polarization control system, a terminal, and a control method for receiving a desired wave.

[0002]

2. Description of the Related Art As a technique for reducing the degradation of communication quality due to interference waves and multipath fading in a radio propagation path and increasing system capacity, the reception output of an array antenna is controlled to control a desired wave. A function for maximizing the desired value of the output signal to the interference wave and the noise level ratio (hereinafter referred to as output SINR) by controlling the maximum value of the radiation pattern and the zero point of the radiation pattern with respect to the interference wave. There is an adaptive transceiver with.

Conventionally, as an apparatus capable of realizing such a function, for example, as shown in FIG. 7, antenna elements are arranged in N elements (A1 to AN) and each element Ai (i = i
1,2,..., N) output xi,
Weighting wi (i = 1, 2,...,
N) is performed by the weighting device 30, and the weighted outputs are combined by the combining device 40 to obtain a desired output. In the diagram shown in the figure, the transmission / reception device 20 demodulates each reception signal of each of the antenna elements A1 to AN, obtains baseband signals for each antenna element, and synthesizes these baseband signals with the synthesis device 40. The signals are input to the control device 50, and the weighting device 30 weights the baseband signals corresponding to each of the antenna elements A1 to AN by the weighting device 30.
By multiplying by WN, control is performed so that the maximum value of the radiation pattern of the array including the antenna elements A1 to AN is directed to the desired wave direction and the zero point is directed to the interference wave direction. To control the radiation pattern of the array antenna, the antenna elements A1
Weights W1 to W
N, the weights W1 to WN are given to the respective received high-frequency signals of the antenna elements A1 to AN, or each of the antenna elements A1
Weights may be given to intermediate frequency signals corresponding to .about.AN. This is also true of the present invention.

When this apparatus is applied to a land mobile communication system, the polarization used for each antenna element Ai is easily omnidirectional in a horizontal plane by a linear antenna such as a dipole having a simple structure and excellent in installation. Vertical polarization has been commonly used because of its flexibility. However, the related art using only the vertical polarization element has the following problems. FIG. 8 is a diagram illustrating an example of a problem in the related art. The base station in the mobile communication system used an adaptive transceiver having 6 vertically polarized elements and a 6-branch half-wavelength interval linear array antenna, and the mobile terminal used a transceiver having a vertically polarized element antenna. XPD means the cross polarization discrimination degree of the propagation path, and is set to 5 dB in this example. The number of trials for randomly arriving waves for two terminals in a 120-degree sector range was set to 1000. The arrival angle difference is
It is defined by the difference between the direction of arrival of the mobile terminal and the direction of arrival of the first mobile terminal, and the relationship between this and the output SINR is determined. From this figure, it can be seen that as the difference between the arrival direction of the desired wave and the arrival direction of the interference wave becomes smaller, the zero point of the radiation pattern cannot be completely directed to the interference wave, and the interference power cannot be suppressed completely. It can be seen that the output SINR deteriorates. As the number of mobile terminals accessing simultaneously increases, the probability that the arrival direction of the desired wave approaches the arrival direction of the interference wave increases.
Deterioration of NR is a problem from the viewpoint of deterioration of communication quality and increase of system capacity.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polarization control system, a terminal, and a control method which reduce deterioration of communication quality and realize control for increasing system capacity. is there.

[0006]

In order to solve the above-mentioned problems, a radio terminal according to the present invention includes a first antenna element having a predetermined polarization characteristic and a polarization characteristic of the first antenna element. It has a second antenna element having a polarization characteristic orthogonal to the first antenna element, and a control device for selecting the first antenna element or the second antenna element as a transmission / reception antenna. A polarization control system according to the present invention includes: a first antenna having a predetermined polarization characteristic; a second antenna having a polarization characteristic orthogonal to the polarization characteristic of the first antenna; A synthesizing device for synthesizing output signals of the antenna and the second antenna, a monitoring unit for monitoring an output signal SINR of the synthesizing device or a desired wave to interference wave level ratio (hereinafter referred to as output SIR) of the output signal and a terminal The terminal transmission polarization setting unit for setting the transmission polarization and the SI of the output signal as the reception polarization of the newly allocated terminal.
And a control device including a polarization allocating unit that allocates the polarization having the higher R or SINR.

The polarization control system of the present invention allows a newly allocated terminal to transmit with predetermined polarization characteristics, measures the SIR or SINR of the transmission wave of each existing terminal, and calculates the SIR or SINR of the measurement result. Minimum value SIR (V) or S
INR (V) is selected and transmitted to a newly allocated terminal with a polarization characteristic orthogonal to a predetermined polarization characteristic, and the SIR or SINR of the transmission wave of each existing terminal is measured. Or the minimum value of SINR SIR (H) or SI
Select NR (H), SIR (V) or SINR (V)
A polarization characteristic is allocated to the newly allocated terminal so that transmission is performed with a polarization characteristic corresponding to the larger one of SIR (H) or SINR (H).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1A shows a configuration of a terminal according to the present invention. The terminal includes a first antenna element 10 having a predetermined polarization characteristic, a second antenna element 11 having a polarization characteristic orthogonal to the polarization characteristic of the first antenna element 10, a transmission / reception antenna As the first antenna element 10 or the second
And a transmitting / receiving device 14. That is, in this example, the transmission / reception device for the first antenna element 10 and the transmission / reception device for the second antenna element 11 can be switched by the control device 13.

FIG. 2 shows the configuration of the polarization control system (base station) of the present invention. This embodiment is a case where the present invention is applied to an adaptive array. The base station has a plurality of antenna elements A
, A3, and A3 having predetermined polarization characteristics.
Array antenna 60 and a plurality of antenna elements A4, A
5 and A6, a fourth array antenna 61 having a polarization characteristic orthogonal to the polarization characteristic of the third array antenna 60, a third array antenna 60 and a fourth array antenna 61 Weighting device 30 that weights the output signals of the respective antenna elements A1 to A6
A combining device 40 that combines the signals output from the weighting device 30, an SINR monitoring unit 71 that monitors the SINR of the output signal of the combining device 40, and a terminal transmission polarization setting unit 72 that sets the transmission polarization of the terminal. A weighting factor calculator that includes a polarization allocating unit 73 that allocates a polarization having a higher SINR of an output signal as a transmission polarization of a newly allocated terminal, and calculates weighting factors W1 to W6 based on an output signal of the combining device 40. Part 74
And a control device 70 for controlling the weighting factors W1 to W6 of the weighting device 30. The first antenna element 10 and the second antenna element 11 of the terminal or the antenna elements of the third array antenna 60 and the fourth array antenna 61 of the base station are fed to different points in one element. It is also possible to use a point that can change the polarization direction of a receivable radio wave. For example, a circular microstrip antenna. Thereby, the first antenna element 10 and the second antenna element 1
In order for the first or third array antenna 60 and the fourth array antenna 61 to be completely common to each element,
It is possible to prevent a reduction in the effect of removing unnecessary waves based on the position deviation.

For example, in a terminal, a circular microstrip antenna 10 'is provided as shown in FIG.
And the switching of the feeding point of the feeding point switching unit 15 is performed by the control device 13. Also, in the base station, the third array antenna 6
By using the circular microstrip antenna as each antenna element of the 0th and fourth array antennas 61 and simultaneously feeding the two feed points to simultaneously transmit and receive two polarized waves, the position deviation can be reduced. It is possible to prevent the unnecessary wave removing effect from being lowered.

FIG. 3 shows an example of a processing procedure of a space / polarization control method in the control device 70 according to the polarization control system of the present invention. First, the number k (k is 1 or more and n
The following integer is initialized to 1 (S1), and communication between the base station and the terminal is performed with a predetermined polarization (S2). The output signal (hereinafter simply referred to as an output signal) of the synthesizer 40 at that time. S
The INR is measured (S3). Next, it is checked whether or not the number n of terminals to be accessed simultaneously (n is an integer of 1 or more) is 2 or more (S4). In other words, if the number of simultaneous access terminals is one of the k-th terminals newly assigned,
Communication between the base station and the terminal is performed using the predetermined polarization assigned in step S2.

Next, in step S4, the number of simultaneous access terminals n
Is determined to be 2 or more, k is updated to 2 (S5), and it is checked whether or not k is equal to or less than n (S6). If k is not less than n, the polarization for the newly assigned k-th terminal is determined as described later. Is completed, the SINR of the output signal is measured, and the process ends (S7). If k is equal to or less than n, a control signal for allocating a predetermined polarization V, for example, a vertical polarization, to the k-th terminal to be newly allocated is transmitted by, for example, a control channel (S8). Based on this transmission, the newly assigned k-th terminal transmits with polarization V (S
9). In this state, i indicating an existing terminal (i is 1 or more and k-1
(The following integer) is initialized to 1 (S10), and the i-th terminal is caused to transmit with a predetermined polarization assigned to it (S11),
At the reception level based on the cross polarization discrimination degree XPD of the propagation path at that time, the radio waves of the predetermined polarizations V and H are received (S1).
2) Then, the SINR (i) at that time is obtained (S13). Thereafter, it is checked whether i is equal to or smaller than k-1 (S14), and k-1 is determined.
If it is below, that is, if there is an existing terminal whose interference state with the radio wave of the existing terminal has not been checked, i is incremented by 1 and step S11
Then, the SINR (i) is measured for the next i-th terminal (S15).

When the measurement of the interference state, that is, SINR (i), of the polarization V of the newly assigned k-th terminal with respect to all the existing terminals, ie, the predetermined polarizations V of the first to k-1th existing terminals, is completed. The minimum SINR (V) of these (k-1) SINR (i) is selected (S16). Note that k + i = n
It is. Next, a control signal for allocating a polarization H (for example, horizontal polarization) orthogonal to the predetermined polarization V is transmitted to the k-th newly allocated terminal (S17). Therefore, the newly assigned k-th terminal is the polarization H
(S18). In this state, i is initialized to 1 (S19), and the i-th existing terminal is caused to transmit with the predetermined polarization assigned to it (S20). At the reception level based on the XPD at that time, the predetermined polarization V and H are compared. Each radio wave is received (S2
1) Then, the SINR (i) at that time is obtained (S22). i
It is checked whether or not is less than or equal to k-1 (S23). If it is k-1, i is incremented by 1, and the process returns to step S20 to measure SINR (i) for the next i-th terminal (S2).
4). In this way, SIN for all existing terminals
When R (i) is measured, the minimum value SINR (H) of these SINR (i) is selected (S25).

The SINR (H) and the previously selected SIN
R (V) is compared (S26), and the higher SINR is selected. That is, the polarization with the higher SINR is assigned to the newly assigned k-th terminal, and the SINR is output (S2).
7), k is incremented by 1, and the process returns to step S6. Therefore, if k is n
The same operation is performed until the polarization assignment is completed, that is, until the polarization assignment is completed for all of the newly assigned terminals. From the above results, in the base station receiving at the reception level based on the XPD with the predetermined polarization and the polarization orthogonal thereto, the predetermined polarization or the polarization orthogonal thereto with respect to the k-th terminal newly assigned is determined. If assigned, the output SIN of the k-1 existing terminal
By comparing the minimum value of R and selecting the polarization having the higher value and assigning it to the newly assigned k-th terminal, the system capacity of the base station that communicates with a terminal group having the number n of simultaneous access terminals is reduced. Increase.

The polarization assignment control for the new terminal shown in FIG. 4 is performed by the polarization assignment unit 73 shown in FIG. 2, and the computer can interpret and execute the program to function. That is, for example, as shown in FIG.
Monitoring unit 71, terminal transmission polarization setting unit 72, existing terminal transmission control unit 81, storage unit 82, memory 83 storing a polarization control program, basic program memory 84, CPU 85
Are connected to the bus 86. Step S8 in FIG.
The generation of a control signal to be transmitted to the newly assigned k-th terminal with predetermined polarization characteristics in step S17 is performed by the terminal transmission polarization setting unit 72, and the assigned polarization is assigned to the i-th existing terminal in steps S11 and S20. Generation of a control signal to be transmitted in step S1 is performed by the existing terminal transmission control unit 81, and in step S1
3. Each SI from the SIN monitoring unit 71 measured in S22
The NR (i) is stored in the storage unit 82, and the CPU 85 interprets and executes the polarization control program, whereby the processing shown in FIG. 3 is executed. In order to transmit and receive the polarization characteristics determined in step S27, the terminal transmission polarization setting section 72 also generates a control signal to be allocated to the newly allocated k-th terminal.

As can be understood from the polarization control procedure shown in FIG. 3, the present invention is not limited to an adaptive transceiver using an array antenna. The polarization characteristic and the polarization characteristic orthogonal to the polarization characteristic can be assigned so that interference is minimized, and the system capacity of the base station communicating with the number of simultaneous access terminals can be increased accordingly. In the above description, SIR (desired wave to interference wave level ratio) may be used instead of SINR.
Further, the present invention can be applied to any access method such as TDMA, FDMA, and CDMA. Further, as described in the section of the prior art, when the present invention is applied to an adaptive transceiver, weighting of a signal corresponding to each antenna element is performed in any of a high frequency stage, an intermediate frequency stage, and a baseband stage. Is also good.

[0017]

As described above, according to the present invention, simultaneous access is possible by selectively assigning a desired polarization characteristic and a polarization characteristic orthogonal thereto to a terminal so as to minimize interference. The number of terminals can be increased, and the system capacity of the base station can be increased. Next, a description will be given of an experimental example by computer simulation when the present invention is applied to an adaptive transceiver.

FIG. 5 shows an example. Here, the conventional configuration is an adaptive transceiver having a 6-vertical polarization element and a 6-branch half-wavelength interval linear array shown in FIG. 7, and the proposed configuration is a 3-vertical polarization element of the present invention shown in FIG. This is a space / polarization control system with three horizontal polarization elements and six branches and a half-wavelength interval linear array. XPD is 5 dB. The number of trials for randomly arriving waves in the range of 20 degrees for two terminals is set to 1000. The arrival angle difference is defined as the difference between the arrival direction of the second terminal and the arrival direction of the first terminal, and the relationship between this and the output SINR is determined. From this figure, in the prior art using only the vertical polarization element, as the difference between the arrival direction of the desired wave and the arrival direction of the interference wave becomes smaller, the zero point of the radiation pattern cannot be completely directed to the interference wave. It can be seen that the output SINR deteriorates due to the inability to suppress the interference power. However, it can be seen that in the proposed configuration, even when the difference between the arrival direction of the desired wave and the arrival direction of the interference wave is small, terminals can be separated based on the difference in polarization components.

FIG. 6 shows another experimental example. Here, the conventional configuration is the adaptive transmission / reception device having the 6 vertical polarization elements and the 6-branch half-wavelength interval linear array shown in FIG. 7, and the proposed configuration is the 3 vertical polarization elements of the present invention shown in FIG. This is a space / polarization control system with three horizontal polarization elements and six branches and a half-wavelength interval linear array. XPD is 5 dB. The number of trials for randomly arriving an incoming wave in the range of 120-degree sector for each number of terminals is set to 1000, and the relationship between the number of simultaneous access terminals and the output SINR cumulative probability 50% value is obtained. As the number of simultaneous access terminals increases, the probability that the arrival directions of the desired wave and the interference wave approach each other increases. As shown in FIG. 5, in the proposed configuration, even when the difference between the arrival direction of the desired wave and the arrival direction of the interference wave is small, terminals can be separated by the difference in polarization components. However, it can be seen that the output SINR decreases more gradually than in the conventional configuration.

As described above, according to the present invention, the base station allocates the polarization for transmitting and receiving to the terminal such that the output SINR or SIR is transmitted with the polarization having the higher output. In the related art using the technique described above, it is possible to compensate for the deterioration of the output SINR or SIR due to the inability to completely suppress the interference power. With this effect, deterioration of communication quality can be reduced and system capacity can be increased. Further, it is possible to reduce the antenna installation space as compared with the conventional configuration having only the same number of vertical polarization elements.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a mobile communication terminal according to the present invention.

FIG. 2 is a diagram showing a configuration example of a polarization control system of the present invention.

FIG. 3 is a flowchart illustrating an example of a polarization control method according to the present invention.

FIG. 4 is an exemplary view showing a configuration example in a case where a computer performs the processing shown in FIG. 3;

FIG. 5 is a diagram showing an example of a relationship between an arrival angle difference between two terminal radio waves and an output SINR as an effect example of the present invention.

FIG. 6 is a diagram showing an example of the relationship between the number of simultaneous access terminals and the output SINR as another example of the effect of the present invention.

FIG. 7 is a diagram showing a configuration example of a conventional adaptive transceiver.

FIG. 8 is a diagram showing an example of the relationship between the arrival angle difference between two terminal radio waves and the output SINR for explaining an example of the problem of the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 20 transmission / reception device 30 weighting device 40 combining device 60 third array antenna 61 fourth array antenna 70 control device 71 SINR monitoring unit 72 terminal transmission polarization setting unit 73 polarization assignment unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 7/26 H04B 7/26 B H04L 27/00 D H04L 27/00 Z (72) Inventor Keizo Tokyo 2-3-1, Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Toshikazu Hori 2-3-1, Otemachi, Chiyoda-ku, Tokyo F-term (reference) 5J021 AA05 CA06 DB02 DB03 DB04 EA04 FA14 FA15 FA16 FA17 FA20 FA31 FA32 GA02 HA05 HA10 JA05 5K004 AA01 BA02 BB01 5K059 CC03 CC05 DD31 5K067 AA23 AA42 BB02 CC24 EE02 FF16 GG01 GG11 KK03

Claims (6)

[Claims] A first antenna having a predetermined polarization characteristic; a second antenna having a polarization characteristic orthogonal to the polarization characteristic of the first antenna; and an output signal of the first antenna. A synthesizing device for synthesizing the output signal of the second antenna, and a desired signal to interference wave signal level ratio (hereinafter referred to as SIR) or a desired signal to interference wave signal and noise level ratio (SIR) of the output signal of the synthesizing device. A monitoring unit for monitoring SINR), a terminal transmission polarization setting unit for setting the transmission polarization of the terminal,
As the transmission polarization of the newly assigned terminal, the SIR of the output signal
Or a control device having a polarization allocating unit that allocates a polarization having a higher SINR. 2. The first antenna is an array antenna composed of a plurality of antenna elements having the polarization characteristics, and the second antenna is composed of a plurality of antenna elements having the polarization characteristics. A weighting device for weighting an output signal of each antenna element of the first array antenna and the second array antenna, wherein the control device is configured to control the weight of the weighting device based on the output signal. The polarization control system according to claim 1, further comprising a weight coefficient generation unit that controls the coefficient. 3. An antenna in which the direction of polarization of radio waves that can be transmitted and received is changed by using different points of one antenna element as feed points as the first antenna and the second antenna. 3. The polarization control system according to claim 1, wherein a transmission / reception device is connected to the both feeding points of the antenna. 4. A first antenna element having a predetermined polarization characteristic and a second antenna element orthogonal to the polarization characteristic of the first antenna element.
A mobile communication terminal comprising: an antenna element; and a control device that selects the first antenna element or the second antenna element as a transmission / reception antenna according to a received terminal transmission polarization setting signal. 5. The first antenna element and the second antenna element are configured as one antenna element that can change the direction of polarization of radio waves that can be transmitted and received by using different points of one antenna element as feed points. The mobile communication terminal according to claim 4, further comprising a power supply point switching unit that controls the switching of the power supply point by the control device. 6. A transmission polarization control method for a mobile terminal by a polarization control system, comprising: transmitting a polarization allocation control signal to a newly allocated terminal so as to transmit with a predetermined polarization characteristic. In the state where the transmission polarization is set to the predetermined polarization characteristic for the newly allocated terminal, a desired wave signal to interference wave level ratio (hereinafter referred to as SIR) or a desired wave signal pair for a transmission wave of each existing terminal is set. Interference wave and noise level ratio (hereinafter referred to as SINR)
A first measuring step of measuring the SIR or SINR measured in the first measuring step, a step of selecting a minimum value SIR (V) or SINR (V) of the SIR or SINR, Transmitting a polarization assignment control signal so as to transmit with a polarization characteristic orthogonal to the wave characteristic; and transmitting a polarization direction orthogonal to the predetermined polarization characteristic to the newly assigned terminal. A second measurement process of measuring the SIR or SINR for the transmission wave of each existing terminal in a state where the characteristics are set, and a minimum value SIR (H) or SINR (H) of the SIR or SINR measured in the second measurement process. Selecting, and comparing the minimum value SIR (V) or SINR (V) with the minimum value SIR (H) or SINR (H). In this comparison, the bias corresponding to the higher SIR or SINR Wave characteristics Terminal control method for polarization control system having a process of transmitting to the new assignment terminals polarization characteristics allocation control signals to assign a polarization characteristic to transmit.