JP3612010B2 - Polarization control system and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polarization control system, a terminal, and a control method therefor, which can receive a desired signal wave (hereinafter referred to as “desired wave”) by removing the interference wave in an environment where the interference wave exists.
[0002]
[Prior art]
As a technique to reduce communication quality degradation due to interference waves and multipath fading in the radio propagation path and increase system capacity, the maximum value of the radiation pattern for the desired wave is controlled by controlling the array antenna reception output. Adaptive transmitter / receiver with the function of maximizing the desired signal to interference wave and noise level ratio (hereinafter referred to as output SINR) of the output signal by controlling the zero point of the radiation pattern with respect to the interference wave There is.
[0003]
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 = 1, 2,..., N). Weight wi (i = 1, 2,..., N) corresponding to the level, direction, and the like of the incoming wave is output by the weighting device 30 and the weighted output is synthesized by the synthesis device 40. Get the output. In this figure, the received signals of the antenna elements A1 to AN are demodulated by the transmission / reception device 20 to obtain baseband signals for the respective antenna elements, and these baseband signals are combined with the synthesis device 40. A signal is input to the control device 50, and a baseband signal corresponding to each of the antenna elements A1 to AN is multiplied by the weights W1 to WN by the weighting device 30, and the radiation pattern of the array including the antenna elements A1 to AN is obtained. Is controlled so that the maximum value is directed to the desired wave direction and the zero point is directed to the interference wave direction. In order to control the radiation pattern of the array antenna, the weights W1 to WN are not given to the corresponding baseband signals of the antenna elements A1 to AN, but the received high frequency signals of the antenna elements A1 to AN are weighted. W1 to WN may be given, or weights may be given to intermediate frequency signals corresponding to the antenna elements A1 to AN in the transmission / reception device 20. This is also true in the present invention.
[0004]
In addition, when this apparatus is applied to a land mobile communication system, the polarization used for each antenna element Ai is easily obtained with a linear antenna such as a dipole that has a simple structure and excellent installation properties, and is easily omnidirectional in a horizontal plane. For this reason, vertical polarization has been generally used.
However, the following problems occur in the conventional technique using only the vertical polarization element. FIG. 8 is a diagram showing an example of a problem of the prior art. The base station in the mobile communication system used an adaptive transceiver having 6 vertical polarization elements and a 6-branch half-wavelength interval linear array antenna, and the mobile terminal used a transceiver having a vertical polarization element antenna. XPD means the cross polarization discrimination degree of the propagation path, and is 5 dB in this example. The number of trials for randomly generating incoming waves in the range of 120 degrees sector for two terminals was set to 1000. The arrival angle difference is defined as the difference between the arrival direction of the second mobile terminal and the arrival direction of the first mobile terminal, and the relationship between this difference and the output SINR is obtained. From this figure, 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. 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 and the arrival direction of the interference wave approach each other increases. Therefore, the degradation of the output SINR in the conventional system causes the degradation of the communication quality and the increase of the system capacity. It is a problem from the point of view.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide a polarization control system, a terminal, and a control method that can realize a control for increasing the system capacity by reducing the deterioration of communication quality.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, a wireless terminal of the present invention has a first antenna element having a predetermined polarization characteristic and a polarization characteristic orthogonal to the polarization characteristic of the first antenna element. A second antenna element, and a control device that selects the first antenna element or the second antenna element as a transmission / reception antenna.
The 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, Of the output signal SINR or the desired signal to interference wave level ratio (hereinafter referred to as output SIR) of the output signal of the combiner and the terminal A terminal transmission polarization setting unit for setting a transmission polarization and a control device including a polarization allocation unit for allocating a polarization having a higher SIR or SINR of an output signal as a reception polarization of a newly allocated terminal.
[0007]
The polarization control system of the present invention causes a newly assigned terminal to transmit with a predetermined polarization characteristic, measures the SIR or SINR for the transmission wave of each existing terminal, and the SIR or SINR minimum value SIR of this measurement result Select (V) or SINR (V),
The newly allocated terminal is transmitted with a polarization characteristic orthogonal to a predetermined polarization characteristic, and the SIR or SINR with respect to the transmission wave of each existing terminal is measured. The minimum value SIR (H ) Or SINR (H),
A polarization characteristic is assigned to the newly assigned terminal so that transmission is performed with a polarization characteristic corresponding to the larger of SIR (V) or SINR (V) and SIR (H) or SINR (H).
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1A shows the configuration of the terminal of the present invention. The terminal includes a first antenna element 10 having a predetermined polarization characteristic, a second attenuator element 11 having a polarization characteristic orthogonal to the polarization characteristic of the first antenna element 10, and a transmission / reception antenna. As a control device 13 that selects the first antenna element 10 or the second antenna element 11 and a transmission / reception device 14. That is, in this example, the transmission / reception apparatus for the first antenna element 10 and the transmission / reception apparatus for the second antenna element 11 can be switched by the control device 13.
[0009]
FIG. 2 shows the configuration of the polarization control system (base station) of the present invention. This embodiment is applied to an adaptive array. The base station is composed of a plurality of antenna elements A1, A2, A3 and has a third array antenna 60 having a predetermined polarization characteristic, and a plurality of antenna elements A4, A5, A6. A fourth array antenna 61 having a polarization characteristic orthogonal to the polarization characteristics of the first and second antenna elements A1 to A6 of the third array antenna 60 and the fourth array antenna 61. Weighting device 30 for weighting, combining device 40 for combining signals output from weighting device 30, SINR monitoring unit 71 for monitoring the SINR of the output signal of combining device 40, and terminal for setting the transmission polarization of the terminal The transmission polarization setting unit 72 includes a polarization allocation unit 73 that allocates a polarization having a larger SINR of the output signal as a transmission polarization of the new allocation terminal. It includes a weighting factor calculator 74 for calculating a weighting factor W1~W6 based on force signals, and a control unit 70 which controls the weight coefficient W1~W6 weighting device 30. It should be noted that 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 in 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. As a result, the first antenna element 10 and the second antenna element 11 or the third array antenna 60 and the fourth array antenna 61 are completely shared by the respective elements. A reduction in the wave removal effect can be prevented.
[0010]
For example, in the terminal, as shown in FIG. 1B, a circular microstrip antenna 10 'is provided, and the feeding point can be switched by the feeding point switching unit 15 to be connected to the transmission / reception device 14. The feeding point switching unit The control device 13 performs switching of the 15 feeding points. In the base station, the circular microstrip antenna is used as each antenna element of the third array antenna 60 and the fourth array antenna 61, and the two feeding points are fed simultaneously to transmit and receive two polarizations simultaneously. By doing so, it is possible to prevent a reduction in unnecessary wave removal effect based on the position deviation.
[0011]
FIG. 3 shows an example of the processing procedure of the 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 an integer from 1 to n) of a newly allocated terminal is initialized to 1 (S1), communication between the base station and the terminal is performed with a predetermined polarization (S2), and the combining device 40 at that time SINR of the output signal (hereinafter simply referred to as output signal) is measured (S3). Next, it is checked whether the number n (n is an integer greater than or equal to 1) of terminals that access simultaneously is 2 or more (S4). That is, when the number of simultaneously accessed terminals is one of the newly assigned k-th terminals, communication between the base station and the terminals is performed with the predetermined polarization assigned in step S2.
[0012]
Next, when it is determined in step S4 that the number n of simultaneous access terminals is 2 or more, k is updated to 2 (S5), and it is checked whether k is n or less (S6). Thus, since the allocation of the polarization to the new allocation k-th terminal is completed, the SINR of the output signal is measured and the process ends (S7).
If k is n or less, a control signal for assigning a predetermined polarization V, for example, a vertical polarization, is transmitted to the newly assigned k-th terminal by using, for example, a control channel (S8). Based on this transmission, the newly assigned k-th terminal transmits with polarization V (S9). In this state, i indicating an existing terminal (i is an integer not less than 1 and not more than k-1) is initialized to 1 (S10), and the i-th terminal transmits with a predetermined polarization assigned thereto (S11), The radio waves of predetermined polarizations V and H are received at the reception level based on the cross polarization discrimination degree XPD of the propagation path (S12), and the SINR (i) at that time is obtained (S13). Thereafter, it is checked whether i is equal to or less than k−1 (S14). If it is equal to or less than k−1, that is, if there is an existing terminal whose interference state with the radio wave of the existing terminal is not checked, i is incremented by 1 and the process proceeds to step S11. Then, SINR (i) is measured for the next i-th terminal (S15).
[0013]
When the measurement of the interference state, that is, SINR (i) with the polarization V of the newly assigned k-th terminal is completed for all the existing terminals, that is, the predetermined polarization V of the first to (k-1) -th existing terminals, these (k -1) The minimum SINR (V) is selected from the SINR (i) (S16).
Note that k + i = n.
Next, a control signal for allocating a polarization H (eg, horizontal polarization) orthogonal to the predetermined polarization V is transmitted to the new allocation k-th terminal (S17). Therefore, the newly assigned k-th terminal transmits with polarization H (S18). In this state, i is initialized to 1 (S19), and the i-th existing terminal is transmitted with the predetermined polarization assigned thereto (S20), and the predetermined polarizations V and H are received at the reception level based on the XPD at that time. Each radio wave is received (S21), and the SINR (i) at that time is obtained (S22). It is checked whether i is equal to or less than k−1 (S23). If k−1, i is incremented by 1, and the process returns to step S20 to measure SINR (i) for the next i-th terminal (S24). ). When SINR (i) is measured for all existing terminals in this way, the minimum value SINR (H) in these SINR (i) is selected (S25).
[0014]
This SINR (H) is compared with the previously selected SINR (V) (S26), and the higher SINR is selected, that is, the polarization having the higher SINR is assigned to the newly assigned k-th terminal. SINR is output (S27), k is incremented by 1, and the process returns to step S6. Therefore, the same operation is performed until k becomes equal to n, that is, until polarization allocation is completed for all the newly assigned terminals.
From the above results, in the base station that receives a predetermined polarization at a reception level based on XPD and a polarization orthogonal thereto, a predetermined polarization or a polarization orthogonal to the newly assigned k-th terminal is obtained. When assigned, the minimum number of output SINRs of the existing terminals of k−1 is compared, and the higher polarization is selected and assigned to the newly assigned k-th terminal, so that the number of simultaneous access terminals is n. The system capacity of the base station that communicates with the terminal group increases.
[0015]
The polarization allocation control for the new terminal shown in FIG. 4 is performed by the polarization allocation unit 73 in FIG. 2, which can be made to function by interpreting and executing the program by a computer. That is, for example, as shown in FIG. 4, the SINR monitoring unit 71, the terminal transmission polarization setting unit 72, the existing terminal transmission control unit 81, the storage unit 82, the memory 83 storing the polarization control program, the basic program memory 84, and the CPU 85 It is connected to the bus 86. In step S8 and step S17 in FIG. 3, the terminal transmission polarization setting unit 72 generates a control signal to be transmitted with a predetermined polarization characteristic for the newly assigned k-th terminal in step S8, and the i-th existing in steps S11 and S20. The control signal to be transmitted to the terminal with the allocated polarization is generated by the existing terminal transmission control unit 81, and each SINR (i) measured from the SIN monitoring unit 71 measured in steps S 13 and S 22 is stored in the storage unit 82. The CPU 85 interprets and executes the polarization control program, whereby the processing shown in FIG. 3 is executed. In order to transmit / receive the polarization characteristic determined in step S27, the terminal transmission polarization setting unit 72 also generates a control signal to be allocated to the newly allocated k-th terminal.
[0016]
As can be understood from the polarization control procedure shown in FIG. 3, the present invention is not necessarily limited to an adaptive transceiver using an array antenna, and even when adaptive control is not performed, a predetermined polarization characteristic is used as a transmission / reception radio wave of each terminal. And a polarization characteristic orthogonal thereto can be allocated so that interference does not occur as much as possible, 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. Furthermore, the present invention can be applied to any access method such as TDMA, FDMA, and CDMA. Furthermore, as described in the section of the prior art, when the present invention is applied to an adaptive transceiver, weighting for signals corresponding to each antenna element is performed at any of a high frequency stage, an intermediate frequency stage, and a baseband stage. Also good.
[0017]
【The invention's effect】
As described above, according to the present invention, it is possible to increase the number of terminals that can be simultaneously accessed by selectively assigning desired polarization characteristics and orthogonal polarization characteristics to the terminals so that there is less interference. The system capacity of the base station can be increased.
Next, an experimental example by computer simulation when the present invention is applied to an adaptive transceiver will be described.
[0018]
An example is shown in FIG. Here, the conventional configuration is an adaptive transmitter / receiver having 6 vertical polarization elements and a 6-branch half-wavelength 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 a linear arrangement of 3 horizontal polarization elements and a half-wavelength interval of 6 branches. XPD is 5 dB. The number of trials for randomly generating an incoming wave 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 difference and the output SINR is obtained. From this figure, in the conventional technology using only a vertical polarization element, the zero point of the radiation pattern cannot be completely directed to the interference wave as the difference between the arrival direction of the desired wave and the arrival direction of the interference wave becomes smaller. It can be seen that the output SINR is deteriorated due to the fact that the interference power cannot be suppressed. However, it can be seen that in the proposed configuration, terminals can be separated by the difference in polarization components even when the difference between the arrival direction of the desired wave and the arrival direction of the interference wave is small.
[0019]
FIG. 6 shows another experimental example. Here, the conventional configuration is an adaptive transmission / reception apparatus of 6 vertical polarization elements and a 6-branch half-wavelength 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 a linear arrangement of 3 horizontal polarization elements and a half-wavelength interval of 6 branches. XPD is 5 dB. The number of trials for randomly generating an incoming wave in the range of 120 degrees 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% 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 if the difference between the arrival direction of the desired wave and the arrival direction of the interference wave is small, the terminals can be separated by the difference in polarization components. However, it can be seen that the decrease in output SINR is more gradual than in the conventional configuration.
[0020]
As described above, in the present invention, only the vertical polarization element is used by allocating the polarization to be transmitted / received to the terminal so that the base station transmits with the polarization having the higher output SINR or SIR. In the prior art, it is possible to compensate for the degradation of the output SINR or SIR caused by the fact that the interference power cannot be suppressed. With this effect, it is possible to reduce communication quality degradation and increase system capacity. Furthermore, the antenna installation space can be reduced as compared with the conventional configuration in which only the vertically polarized elements having the same number of branches are used.
[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 showing an example of a polarization control method according to the present invention.
4 is a diagram 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 the 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 output SINR as another example of the effect of the present invention;
FIG. 7 is a diagram illustrating a configuration example of a conventional adaptive transceiver.
FIG. 8 is a diagram illustrating a relationship example between an arrival angle difference between two terminal radio waves and an output SINR for explaining an example of a problem of the conventional technology.
[Explanation of symbols]
20 Transmission / Reception Device 30 Weighting Device 40 Synthesizer 60 Third Array Antenna 61 Fourth Array Antenna 70 Control Device 71 SINR Monitoring Unit 72 Terminal Transmission Polarization Setting Unit 73 Polarization Allocation Unit

Claims (4)

In the polarization control system consisting of multiple terminals and base stations,
The terminal
A first antenna element having a predetermined polarization characteristic;
A second antenna element orthogonal to the polarization characteristics of the first antenna element;
A control device that selects the first antenna element or the second antenna element as a transmission / reception antenna based on a control signal from the base station according to a received terminal transmission polarization setting signal;
The base station
A third antenna of an array antenna composed of a plurality of antenna elements having a predetermined polarization characteristic;
A fourth antenna of an array antenna composed of a plurality of antenna elements having polarization characteristics orthogonal to the polarization characteristics of the third antenna;
First and second weighting devices for weighting output signals of the antenna elements of the third antenna and the fourth antenna;
A combining device for combining the output signal of the first weighting device and the output signal of the second weighting device;
The desired signal to interference signal level ratio (hereinafter referred to as SIR ) or the desired signal to interference signal and noise level ratio (hereinafter referred to as SIR ) of the output signal of the synthesis apparatus received at the reception level based on the cross polarization discrimination XPD. The monitoring department, seeking SINR )
A terminal transmission polarization setting unit that transmits a control signal for setting the transmission polarization of the terminal to the terminal;
A weighting factor generator for controlling the weighting factors of the first and second weighting devices based on the output signal of the synthesizer;
Obtain the predetermined polarization set as the transmission polarization of the terminal and the SIR or SINR in the polarization orthogonal thereto ,
A polarization control system comprising: a control device having a polarization allocation unit that allocates a polarization corresponding to a higher one of the obtained minimum values of SIR or SINR as a transmission polarization of a new allocation terminal. As each antenna element of the third antenna and each antenna element of the fourth antenna , there is an antenna element that changes the polarization direction of the radio wave that can be transmitted and received by using a different point of one antenna element as a feeding point. used is, claim 1 Symbol placement polarization control system wherein the transceiver is connected to the two feeding points of the respective antenna elements. The first antenna element and the second antenna element are configured as one antenna element that can change the polarization direction of radio waves that can be transmitted and received by using different points of one antenna element as a feeding point. The polarization control system according to claim 1, further comprising a feeding point switching unit whose switching is controlled by the control device. A transmission polarization control method for a mobile terminal by a polarization control system,
A process of transmitting a polarization allocation control signal to a new allocation terminal so as to transmit with a predetermined polarization characteristic;
A desired wave signal-to-interference wave level ratio (hereinafter referred to as SIR) or a desired wave signal-to-interference with respect to the transmission wave of each existing terminal with the transmission polarization set to the predetermined polarization characteristic for the newly assigned terminal A first measurement process of measuring a wave and noise level ratio (hereinafter referred to as SINR) at a reception level based on the cross polarization discrimination XPD of the propagation path at that time ;
Selecting a minimum SIR (SIR) or SINR (V) of SIR or SINR measured in the first measurement process;
A process of transmitting a polarization allocation control signal to the new allocation terminal so as to transmit with a polarization characteristic orthogonal to the predetermined polarization characteristic;
The SIR or SINR for the transmission wave of each existing terminal in the state where the transmission polarization for the newly allocated terminal is set to a polarization characteristic orthogonal to the predetermined polarization characteristic, and the cross polarization of the propagation path at that time A second measurement process for measuring at a reception level based on the degree of discrimination XPD ;
Selecting the minimum SIR or SINR value SIR (H) or SINR (H) measured in the second measurement process;
Comparing the minimum SIR (V) or SINR (V) with the minimum SIR (H) or SINR (H);
A polarization characteristic allocation control signal for allocating a polarization characteristic to be transmitted with a polarization characteristic corresponding to a higher SIR or SINR in this comparison, and transmitting the polarization characteristic allocation control signal to the new allocation terminal. Control system control method.

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