JP2005109530A - Portable radio terminal equipped with radio wave arrival direction estimating function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of improving call quality without causing increase in power consumption even in a place where electric field intensity is weak. <P>SOLUTION: An electric field intensity monitoring unit 2 obtains the electric field intensity at a point where a terminal exists from the reception level of a radio wave received by a radio wave receiving unit 1. If the electric field intensity is equal to or more than a predetermined level, call is continued without any change. On the contrary, if the electric field intensity is smaller than the predetermined level, since the electric field intensity is weak and call is interrupted, the unit 2 instructs an arrival direction estimating function unit 4 to perform radio wave arrival direction estimating processing with an array antenna. Upon reception of this instruction, the unit 4 executes the radio wave arrival direction estimating processing. The radio wave arrival direction estimated by the unit 4 is displayed on a monitor 3. A user changes the direction of the portable terminal or moves its position while watching the radio wave arrival direction displayed on the monitor 3 so that the electric field intensity may be equal to or more than the predetermined level. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mobile radio terminal such as a mobile phone used in a mobile communication system using a CDMA system, a WCDMA system, or the like.

  For example, a mobile phone uses a whip-like element and an antenna composed of a coil-like element that is insulated from the tip of the whip-like element. Contained and transmitted / received by coil-shaped element. When talking or when reception sensitivity is low, whip-shaped element with high gain is pulled out from housing and transmitted / received by whip-shaped element, or inside of antenna and terminal that extends Wireless communication with a base station is performed by a configuration in which diversity reception is performed using one or both of these antennas.

  In general, these communication antennas are preferably omnidirectional antennas so as to be able to receive radio waves arriving from any direction. Alternatively, the reception sensitivity varies depending on the use state and the like. If you are communicating in a location with a high field strength and a good reception condition, such as near a base station, you can get a sufficient reception level even if the direction is somewhat poor. Communication with the desired call quality can be performed, but if a sufficient reception level cannot be obtained in a location where the electric field strength is weak or a location where the radio wave propagation environment is poor, such as a location away from the base station, If the direction with good directivity and the radio wave arrival direction do not match, it becomes difficult to perform communication with desired call quality.

  As a method for solving such a problem, in Patent Documents 1 and 2, an adaptive array antenna is mounted on a portable wireless terminal, and the direction of a directional beam of the antenna is controlled, so that the state of fading for the portable wireless device is adjusted. The antenna directivity is changed to maintain the call quality. Further, in Patent Document 2, the adaptive array antenna is used to sequentially give directivity to all directions in the horizontal plane of the mobile terminal, and the reception level of the base station to be connected to each direction is measured. 3D display.

  According to the portable wireless terminals described in Patent Documents 1 and 2, since the antenna directivity can be changed according to the fading situation with respect to the portable wireless device, the optimum antenna directivity is always realized regardless of the orientation of the portable terminal. In addition, it is possible to measure and display the radio wave propagation state around the mobile terminal being used in real time, but when such an adaptive array antenna is installed, multiple antennas and these Requires a receiving system attached to each antenna, and requires calculation processing of weighting factors for signals transmitted / received by each antenna, so that the circuit configuration is complicated and the power consumption is increased in exchange for improvement of the receiving state. The problem arises.

  In Patent Document 3, in order to eliminate an increase in power consumption due to the mounting of an adaptive array antenna, a single antenna used for data reception in the single antenna reception mode and data reception in the adaptive array antenna reception mode are used. If there is an adaptive array antenna composed of multiple antennas and the desired call quality can be maintained even with a single antenna in a place where reception is good, other adaptive array antenna reception systems other than the single antenna reception system And the adaptive array antenna reception system is operated only when the desired call quality cannot be maintained with single antenna reception in a place where the reception state is poor, thereby suppressing unnecessary power consumption.

JP 11-98049 A JP 2002-135198 A JP 2003-37547 A JP 2002-048853 A

  However, even in Patent Document 3, if a desired call quality cannot be maintained with single antenna reception in a place where the reception state is poor, it is necessary to operate the adaptive array antenna reception system, and the reception system attached to each antenna In this case, the effect of suppressing power consumption cannot be obtained, and the circuit configuration is complicated.

  When receiving with a single antenna with constant directivity, even if the electric field strength suddenly deteriorates or the location moves to an area where the electric field strength is weak, if the arrival direction of the radio wave is known, It is possible to improve call quality by changing the direction of the portable wireless terminal so that the direction with good antenna directivity matches the direction of arrival of radio waves. In recent years, arrival direction estimation techniques for radio waves have become popular, and high-resolution estimation techniques are being developed with a small number of array elements.

  An object of the present invention is to install a means capable of detecting the direction of arrival of radio waves in a portable wireless device so that a relatively simple configuration can be achieved without increasing power consumption even in a place where the electric field strength is relatively weak. Therefore, it is intended to provide means capable of improving the call quality.

  The present invention provides a portable wireless terminal having a transmission / reception antenna having a constant directivity for performing wireless communication with a base station using radio waves in a predetermined wireless communication frequency band. An array antenna used for detecting the direction of arrival of radio waves of the radio communication frequency; radio wave arrival direction estimating means for estimating the direction of arrival from radio waves of the radio communication frequency received by the array antenna; and A means for displaying the radio wave arrival direction estimated by the direction estimating means on the display unit of the portable wireless terminal is provided.

  The portable wireless terminal equipped with the radio wave arrival direction estimation function of the present invention includes electric field strength monitoring means for monitoring the signal level received by the transmission / reception antenna, and the electric field strength monitoring means is received by the transmission / reception antenna. The radio wave arrival direction estimation means is instructed to execute the radio wave arrival direction estimation operation only when the detected signal level is detected to be lower than a predetermined level.

  According to the present invention, for example, in a mobile communication system using a CDMA system, a WCDMA system, etc., the mobile terminal is equipped with an array antenna for detecting the direction of arrival of radio waves, and the user has good field strength on the monitor. Since the direction can be confirmed, call quality can be improved by changing the orientation of the mobile terminal to optimize the antenna directivity or by moving the mobile terminal in the direction of arrival of radio waves.

  In addition, the array antenna of the present invention is used only for detecting the direction of arrival of radio waves, and is not used as a transmission / reception antenna having the function of an adaptive array antenna. It is relatively simple and the increase in power consumption can be suppressed to a minimum, and the problem of shortening the usage time, which is an important factor for a mobile terminal, can be avoided.

  1 to 3 are diagrams illustrating an embodiment of the present invention. FIG. 1 is a block diagram illustrating a main part of the present embodiment. FIG. 2 is a rear view of the portable wireless terminal according to the present embodiment. It is a front view of the portable wireless terminal of an embodiment.

  The portable wireless terminal of this embodiment includes a radio wave receiving unit 1 that receives data from a base station using a normal transmission / reception antenna, and an electric field intensity monitoring unit 2 that constantly monitors the level of a signal received by the radio wave receiving unit 1. And a radio wave arrival direction estimation function unit 4 that performs radio wave arrival direction estimation using an array antenna arranged in the terminal when the reception level monitored by the electric field strength monitoring unit 2 is equal to or lower than a predetermined level; Direction monitoring unit 5 that constantly monitors in which direction the current terminal is directed by the azimuth magnet, and the reception level monitored by electric field intensity monitoring unit 2 and the radio wave estimated by radio wave arrival direction estimation function unit 4 A monitor 3 is provided for displaying on the terminal screen the direction of arrival and the direction of the terminal monitored by the direction monitoring unit 5.

  As shown in FIG. 2, on the back (rear) side of the casing 10 of the portable wireless terminal, an antenna 11 for transmission / reception and an array (in the figure, a square array of four elements) are arranged to detect the arrival direction of radio waves. A small chip antenna 12 is incorporated. Although not shown, a azimuth magnetic needle that rotates 360 degrees is provided in the housing 10 in order to determine the direction (direction) of the mobile wireless terminal. On the other hand, as shown in FIG. 3, on the front (front) side of the casing 10 of the portable wireless terminal, a key group 13 for performing various operations of the portable wireless terminal, a display unit 14, a transmitter 15, a receiver 16, etc. Is arranged.

  On the display unit 14, the monitor 3 displays a reception level display 17, a direction display 18, and a radio wave arrival direction display 19. In this monitoring method, the direction is determined and displayed on the monitor depending on how many azimuth magnetic needles rotated 360 degrees from a certain reference, and the signal received by the chip-type array antenna 12 embedded in the back of the mobile phone. The direction of arrival estimation function unit 4 estimates the direction of arrival of radio waves based on, and displays a direction 19 on which the radio wave can be easily received is displayed on the monitor.

  As an arrival direction estimation algorithm for estimating a radio wave arrival direction using an array antenna element, a Beamforming method with a small calculation load and a super resolution method capable of performing estimation with higher accuracy can be applied. The antenna configuration is not changed by the direction of arrival estimation algorithm. It is possible to notify the user by displaying on the monitor (display unit 14) wherever the radio waves are incident from the direction obtained with this estimation result and compass It becomes.

  Here, the MUSIC (MUltiple SIgnal Classification) method, which is one of the super-resolution methods and is well known, will be briefly described.

  In this method, a correlation matrix is created from signals incident on each array element with a phase shift, and eigenvalue analysis is performed to obtain a signal component and a noise component. Since the eigenvector of the eigenvalue is orthogonal to the noise vector of the signal, when the angle is swept from −180 degrees to 180 degrees, the value diverges from the evaluation formula, so that the peak value is obtained. The angle at that time is the arrival direction angle of the radio wave. The super resolution method is a general term for methods based on eigenvalue analysis as described above, and the MUSIC method is one of the most common methods. (The details of the MUSIC method are described in Patent Document 4 and the like.)

  FIG. 4 is a processing flow of this embodiment. The operation of this embodiment will be described below with reference to FIGS.

  When radio waves are received by the transmitting / receiving antenna 11 during a call (S11), the electric field strength monitoring unit 2 determines the electric field strength at the location where the terminal exists by monitoring the reception level (S12). The obtained electric field strength k (i) is compared with a certain reference threshold D (S13), and if k (i) ≧ D, a normal call is possible (S14) and the call is performed as it is. On the other hand, when k (i) <D, since the electric field strength k (i) is weak and the call may be interrupted, the electric field strength monitoring unit 2 transmits the radio wave from the array antenna 12 to the arrival direction estimation function unit 4. The arrival direction estimation process is instructed, and the arrival direction estimation function unit 4 receives the instruction and executes the arrival direction estimation process of the radio wave (S15).

  The radio wave arrival direction estimated by the arrival direction estimation function unit 4 is displayed on the monitor (display unit 14) (S16). For example, as shown in FIG. 3, a simple picture of the terminal is displayed on the display surface of the terminal, and the direction in which the terminal is facing is detected and the direction in which the incoming wave is detected is displayed. . The direction of arrival of radio waves can be calculated by using the fact that the direction in which the terminal is facing is known and calculating based on this.

  The user points the terminal in that direction or moves (S17), and monitors the electric field strength display 17 displayed on the monitor as needed to maintain or improve the call quality. At that time, when the movement of the user is detected by some means (for example, the user presses the movement confirmation button, or the change in the electric field intensity accompanying the movement changes by a predetermined level), the electric field intensity monitoring in (S12) is repeated again. If the situation does not improve even if this repetition is repeated n times a certain number of times (i = n), a call interruption process is performed (S18), and this can be displayed on the display unit 14.

  Since the updated information is displayed on the monitor of the terminal as needed by the above operation, the user can improve the call quality by moving the terminal while viewing this display. Then, if the electric field strength is greater than the threshold value D, the callable quality is obtained, so that the call-ready state is restored (S14).

  FIG. 5 shows another embodiment of an array antenna that can be used in the present invention. As shown in the figure, the array antenna can be variously formulated such as a circular array 21, a square array 22, and a linear array 23. In addition, as the number of elements increases, it becomes possible to perform highly accurate estimation. Further, these array antennas can be mounted on the terminal housing 10 or configured as an accessory kit so that they can be attached to the portable terminal.

  On the other hand, in terms of cost, it is more advantageous to reduce the number of elements in the circular array 21, the square array 22, and the linear array 23, and a technique that can accurately estimate the direction of arrival even if the number of elements is thinned is established. ing. Therefore, by applying an appropriate algorithm by changing the software, it is possible to accurately estimate the direction of arrival without changing the hardware in operation.

It is a block diagram which shows the principal part of embodiment of this invention. It is a rear view of the portable wireless terminal of this embodiment. It is a front view of the portable wireless terminal of this embodiment. It is a processing flowchart of this embodiment. It is another Example of the array antenna which can be used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radio wave receiving part 2 Electric field strength monitoring part 3 Monitor 4 Radio wave arrival direction estimation part 5 Direction monitoring part 10 Case of portable terminal 11 Transmission / reception antenna 12 Chip antenna which comprises array antenna 13 Operation key group 14 Display part 15 Transmitter 16 Handset 17 Electric field strength display 18 Direction display 19 Radio wave arrival direction display 21 Circular array 22 Square array 23 Linear array

Claims (5)

In a portable wireless terminal equipped with a transmitting / receiving antenna with a constant directivity for performing wireless communication with a base station using radio waves in a predetermined wireless communication frequency band,
In addition to the transmission / reception antenna, the portable wireless terminal is provided with an array antenna used for detecting the arrival direction of the radio communication frequency radio wave, and the arrival from the radio communication frequency radio wave received by the array antenna. A portable radio terminal comprising: a radio wave arrival direction estimation unit that estimates a direction; and a unit that displays the arrival direction of the radio wave estimated by the radio wave arrival direction estimation unit on a display unit of the portable radio terminal.   Electric field strength monitoring means for monitoring the signal level received by the transmission / reception antenna, the electric field strength monitoring means is only when it is detected that the signal level received by the transmission / reception antenna is below a predetermined level. The portable radio terminal according to claim 1, wherein the radio wave arrival direction estimation unit is instructed to execute the radio wave arrival direction estimation operation.   The portable wireless terminal includes direction monitoring means for detecting a direction in which the terminal is facing, and means for displaying the direction of the portable wireless terminal detected by the direction monitoring means on a display unit of the portable wireless terminal. The portable wireless terminal according to claim 1, wherein the portable wireless terminal is a portable wireless terminal.   The array antenna is composed of a plurality of chip antennas arranged in a circular shape, a square shape, or a linear shape on the back side of the mobile terminal. Mobile wireless terminal.   The portable radio terminal according to claim 1, wherein the array antenna is configured to be attachable to the portable radio terminal as an accessory kit.

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