JPH08139661A - Cellular car telephone - Google Patents

Abstract

(57) [Summary] [Purpose] To properly switch and control communication base stations. [Structure] The position of a communication base station is detected, and the directivity of a directional antenna is controlled in the direction of the communication base station based on the data estimated by the position detecting means. [Effect] It is possible to improve the efficiency and performance of the directional diversity device. Since the arrival directions of radio waves are optimized together, very reliable operation can be expected even in the region where the system is in the most severe conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular type mobile telephone equipped with vehicle position detecting means.

[0002]

2. Description of the Related Art In a car telephone, since the directions of communication base stations are random, an isotropic (omnidirectional) antenna is usually used as the antenna. In addition, in order to overcome the poor propagation environment, interference cancellation measures such as diversity and adaptive equalizer are taken.

In mobile communication such as a car telephone, radio waves are reflected and scattered to form multiple waves and arrive at an antenna.
In reception by an isotropic (omnidirectional) antenna, in addition to direct waves, multiple incoming waves from other directions are all received, and in such a case, the electric field strength is Nakagami-Rice distribution or Rayleigh distribution. It is theoretically and empirically known to undergo the steep and deep fading shown. The application of directional antennas to mobile communication is described in, for example, the article by Ikegami et al., "Effects of antenna directivity on multi-wave fading in mobile communication" (Physics B, vol.J68-B, NO.3, 61-68). Page, March 1985) and the like, the effect of extending the fading cycle is shown by improving the antenna gain in addition to reducing the fading.

As one of the methods of applying a directional antenna to mobile communication, a plurality of directional antennas are prepared and, for example, the antennas are fixedly arranged so as to be in the same azimuth direction. Directivity diversity for selectively switching the receiving antennas or adaptively combining the outputs of the respective antennas, and adaptive array antenna techniques for changing the overall directional characteristics of the antennas in the desired wave direction are known.

Each of these methods is significantly larger than the conventional configuration using an omnidirectional antenna. Also, in the case of an adaptive array antenna, the desired wave is specified from the signal whose amplitude fluctuates drastically due to fading, etc. as the vehicle progresses, and it is possible to make a sharp change in the arrival direction of the desired wave due to changes in the traveling direction of the vehicle. The scale of the device for adaptively following increases greatly, and it is very difficult to implement the algorithm.

[0006]

Since the directions of arrival of signals are random, it is necessary for each antenna to be arranged and fixed such that their total directional characteristics are isotropic. On the other hand, the direction of arrival of the main incoming wave with large signal power is
Although it fluctuates instantaneously due to shielding or the like, especially when directional diversity is applied, it is considered that the radio wave from the base station direction is statistically strong most of the time statistically.
Therefore, when the conventional directional diversity is applied, the branches other than the direction of the base station do not function for most of the time, which is a very inefficient system.

Further, in the cellular type car telephone, a base station for communication is selected according to the position of the mobile station. Since the optimum base station changes as the vehicle moves, the mobile station detects and compares the signal levels of a plurality of base stations and selects the best base station. With a directional antenna,
When detecting the signal level of another station, in addition to the conventional control, antenna directivity control in the direction of the other station is required, which complicates control of the device. On the other hand, as one of the methods for detecting the position of a moving body, a global positioning system (GPS) that uses radio waves from artificial satellites is known. GP
S is much more accurate than the conventional positioning system, and is considered to be applied not only to navigation but also to automobiles and other moving bodies, and navigation devices for automobiles using a database of map information have become widespread. .

In order to overcome the above-mentioned problems of the prior art, an object of the present invention is to detect the position of a conventional vehicle by using the above GPS or APM or other navigation apparatus for automobiles such as AVM. Hereinafter, the switching / control of the communication base station is appropriately performed using the navigation device).

[0009]

In order to solve the above problems, a first invention is directed to a directional antenna, an antenna directional control device for controlling the directional direction of the directional antenna, the position of a communication base station, and A cellular type mobile telephone having a position detecting means for detecting a direction and controlling the directional characteristics of the directional antenna so as to face the communication base station based on the data estimated by the position detecting means.

A second aspect of the present invention detects a plurality of directional antennas, an antenna directivity control device for controlling the directional directions of the plurality of directional antennas, a position and a direction of a communication base station, and a traveling direction of an automobile. Position detecting means for predicting and for predicting the position and direction of the communication base station to be communicated next,
A cellular type mobile telephone is configured to switch the directivity characteristics of the plurality of directional antennas to the directions of the communication base station and the estimated communication base station based on the data estimated by the position detecting means.

[0011]

According to the above construction, since the vehicle position detecting means can select the base station with which the current or / and the next communication is to be made and the directional antenna can be controlled, the communication can be carried out even in a mobile telephone. The base station is controlled and switched appropriately for the purpose.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the construction of a cellular type automobile telephone which is an embodiment of the first invention.

In the figure, information such as the position and height of the base station is entered in the map database referred to by the navigation device 1. If the current position of the vehicle is known by the navigation device 1, the base station currently in communication based on the current vehicle position can be known from the map information in the built-in map database. Therefore, the directivity control device 2 can set the directivity direction of the directional antenna 4 in the current communication base station to the direction of the communication base station.

FIG. 2 is a block diagram showing the construction of a cellular type automobile telephone which is an embodiment of the second invention.

In the figure, information such as the position and height of the base station is input to the map database referred to by the navigation device 11. When the current position of the vehicle is known by the navigation device 11, the base station currently in communication based on the current vehicle position can be known from the map information in the built-in map database. Then, since the traveling direction of the vehicle can be known by using the navigation device 11, the base station for the next communication can be calculated. Therefore, the directivity directions of the plurality of directional antennas 14 and 15 are set to the directions of the respective communication base stations by the plurality of directivity control devices 12 and 13 corresponding to the current and next communication base stations, and the branches are set to the space. Alternatively, it is used as a transmission path selection diversity branch.

Further, since the positions of the two base stations are known, the cell boundary area is known. Then, when the mobile unit advances to the boundary area of the cell, the direction of some antennas is changed from the direction of the communicating base station to the direction of the next base station, and in addition to the signal of the communicating base station, the signal of the next base station is added. Also receives and compares the levels. When the communication base station is switched, it is possible to control the direction of all the antennas to be changed to a new communication base station to perform diversity.

[0018]

As described above, according to the present invention, it is possible to improve the directional diversity device in which the utilization efficiency of the conventional function is very poor by merely applying information without impairing the original function of the navigation device. It is possible to improve efficiency and performance. Also, according to the information of the navigation device, the radio waves of the two base stations interfere with each other in the cell boundary area, and the operation direction of the system is likely to be unstable in the conventional method. Since it is optimized, very reliable operation can be expected even in the most demanding area for the system.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a cellular type car telephone which is an embodiment of the first invention.

FIG. 2 is a block diagram showing a configuration of a cellular type car telephone which is an embodiment of the second invention.

[Explanation of symbols]

 1: Navigation device 2: Directional control device 3: Directional control device 4: Directional antenna 5: Directional antenna

Claims (2)

[Claims] 1. A directional antenna, an antenna directional control device for controlling a directional direction of the directional antenna, and position detecting means for detecting a position and a direction of a communication base station, which are estimated by the position detecting means. A cellular type car telephone characterized in that the directional characteristic of the directional antenna is controlled so as to face the communication base station based on the received data. 2. A plurality of directional antennas, an antenna directional control device for controlling directional directions of the plurality of directional antennas, a position and a direction of a communication base station are detected, and a traveling direction of an automobile is predicted. Position detecting means for predicting the position and direction of the communication base station to communicate with, and the directivity characteristics of the plurality of directional antennas are estimated by the communication base station based on the data estimated by the position detecting means. A cellular car telephone characterized by being switched to a communication base station.