JP3285722B2 - Diversity receiver for mobile phone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiver for a mobile telephone.

[0002]

2. Description of the Related Art In mobile communication such as an automobile telephone, radio waves are reflected and scattered to be multiplexed and arrive at an antenna. Reception by an omnidirectional (omnidirectional) antenna will receive all incoming waves from other directions in addition to the direct wave. In such a case, the electric field strength will be Nakagami-Rice distribution or Rayleigh distribution. It is theoretically and empirically known to undergo steep and deep fading as shown. The application of a directional antenna to mobile communication is described in, for example, a paper by Ikegami et al., "Effects of Antenna Directivity on Multipath Fading in Mobile Communication" (IEEE B, vol. J68-B, NO. 3, 61-68). page,
As shown in March 1985, it has been pointed out that, in addition to reducing the fading, the antenna gain is improved and the fading period is extended.

As a method of applying a directional antenna to mobile communication, a plurality of directional antennas are prepared, and for example, each antenna is fixedly arranged so as to have the same azimuth as a whole, and an optimum receiving antenna at each time is determined. Selective switching, or directional diversity to adaptively combine each antenna output,
There has been known an adaptive array antenna technique for changing the overall directional characteristics of an antenna in the direction of a desired wave.

[0004]

However, in the conventional directional diversity apparatus, since the direction of arrival of a signal is unknown, the directional characteristics of each directional antenna are fixedly arranged so that the overall characteristics become equidirectional. Have been. Although the arrival direction of the main arriving wave with large signal power fluctuates instantaneously due to shielding or the like, especially when directional diversity is applied, statistically most of the time, the arriving wave directly arrives from the base station antenna. It is considered that a signal from a specific direction determined by a propagation environment such as the above is strong. Therefore, when the conventional directional diversity is applied, branches other than one branch do not function for most of the time, resulting in a very inefficient system. Also, the adaptive array antenna identifies a desired wave from a signal whose amplitude fluctuates greatly due to fading or the like as the vehicle travels,
The scale of a device for adaptively following a steep change in the arrival direction of a desired wave due to a change in the traveling direction of a vehicle or the like greatly increases, and it is very difficult to implement an algorithm.

[0005] As one method of detecting the position of a moving object, a global positioning system (GPS) using radio waves from artificial satellites is known. GPS is extremely accurate compared to the conventional positioning system, and is considered to be applied not only to navigation but also to automobiles and other moving objects, and automobile navigation devices using a database of map information have become widespread. .

[0006]

According to the present invention, a current position of a vehicle and a position of a communication base station are detected by an automobile navigation device (hereinafter referred to as a navigation device) such as an AVM using the GPS or the sign post. By specifying the arrival direction of the main arriving wave from the building information around the mobile unit and the communication base station, and directing the directional characteristics of the directional antenna group of the directional antenna group to the arrival direction of each main arriving wave, all the diversity branches are obtained. It is an object of the present invention to propose a diversity receiver in which the received signal quality is dramatically improved.

In order to achieve the above object, the present invention provides an automobile having at least an automobile navigation device, a building database, a plurality of directional antennas, and an antenna directivity control device for controlling the directional antennas. In the diversity receiver for the telephone, to obtain information on the multipath propagation path between the mobile station and the communication base station by the car navigation device and the building database, predict the arrival direction of the main arriving wave from the obtained information, By making the directivity of the directional antenna of each branch coincide with the arrival direction of each main wave by the antenna directivity control device, a diversity receiver for a mobile phone is configured to improve the received signal quality of each branch.

[0008]

According to the above arrangement, a plurality of directional antennas and a device for controlling the directivity of each directional antenna by obtaining the radio wave arrival direction information based on the vehicle traveling direction by the navigation device and the building database are used. And direct the directivity of one antenna toward the communication base station,
Diversity reception is performed by directing the directivity of the other antennas to the surrounding direction such as the traveling direction, and the directivity can be changed by controlling the direction as the vehicle travels.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals. FIG. 1 is a distribution diagram of a radio wave arrival direction based on a traveling direction of a vehicle,
FIG. 2 is a schematic block diagram of a main part of the diversity receiver for a mobile phone according to the present invention.

FIG. 1 is a distribution diagram of a radio wave arrival direction obtained based on, for example, the traveling direction information of a vehicle obtained from a navigation device 1 and a building database built in the navigation device 1 described later. Here, the direction of the communication base station is defined as the main radio wave arrival direction, and AB indicates the radio wave arrival direction of the branch.

Reference numeral 1 denotes an automobile navigation device, which has a built-in database therein. 2, 3,
Reference numeral 4 denotes a plurality of antenna directivity control devices that control the plurality of directional antennas 5, 6, and 7.

The mobile navigation device 1 and the building database acquire information on the multipath propagation path between the mobile station and the communication base station, and predict the arrival direction of the main arriving wave from the acquired information. By making the directivity of the directional antennas 5, 6, 7 of each branch coincide with the arrival direction of each main wave by the directional controllers 2, 3, 4,
The reception signal quality of each branch is improved.

Attempts to model buildings and roads that characterize the propagation environment in urban areas and to estimate the direction of arrival of radio waves are as follows:
For example, a paper by Asano et al., "Estimation of radio wave arrival direction distribution in urban area" (IEICE Technical Report RCS88-52, pp.41-46, 1989)
January) etc., and the possibility of predicting a multi-wave delay profile that also takes into account the multi-wave delay time from a building database that collects information on building position and height has been reported. Attempt to Predict Urban Multipath Delay Profile Using Building Database "(IEICE Technical Report RCS 89-29, pp. 63-68, October 1989).

According to the present invention, the position of a vehicle is detected by a navigation system, and map information around the vehicle is obtained. By linking the map database and the building database referred to by the navigation device and obtaining map information and building information around the vehicle and the communication base station, the main arriving waves in the multiplex wave are selected, and their arrival directions are determined. Predict.

From the navigation device 1 and the building database, a radio wave arrival direction distribution map based on the vehicle traveling direction as shown in FIG. 1 is obtained as described above. A plurality of directional antennas and a device for controlling the directivity of each directional antenna are prepared. According to the information in FIG. 1, the directivity of one antenna is directed to the communication base station, Diversity reception is performed by directing the directivity of the antenna in the directions of A and B. If the pattern of FIG. 1 changes with the progress of the vehicle, each directivity is changed accordingly.

[0016]

As described above, the diversity receiver of the present invention realizes the received directivity diversity effect only by obtaining information of the navigation device.

According to the present invention, the direction of arrival of the main waves is further specified, each of the main waves is received by a directional antenna having high sensitivity and strong against fading, and diversity is performed. Therefore, an extremely high-performance receiver can be configured. . The original function of the navigation device is not impaired at all. Antenna directivity control is also very simple because it is not adaptive control,
The device scale is almost the same as that of the conventional directional diversity receiver.

[Brief description of the drawings]

FIG. 1 is a distribution diagram of a radio wave arrival direction based on a traveling direction of a vehicle.

FIG. 2 is a schematic block diagram of a main part of a diversity receiver for a mobile phone according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 navigation device 2 directivity control device 3 directivity control device 4 directivity control device 5 directional antenna 6 directional antenna 7 directional antenna

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-261928 (JP, A) JP-A-3-220825 (JP, A) JP-A-6-29890 (JP, A) JP-A 8- 139661 (JP, A) Tsuyoshi Hano et al., Prediction of Urban Multi-Wave Delay Profile Using Building Database, IEICE Technical Report, Japan, IEICE, October 24, 1989, RCS89- 29, 63-68 Koichi Asano and 4 others, estimation of the arrival direction distribution of radio waves in an urban area, Technical Report of IEICE, Japan, IEICE, January 20, 1989, RCS88-52, 41 −46 (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 7/10 G01S 5/14 H04B 7/26

Claims (1)

(57) [Claims] 1. A diversity receiving apparatus for an automobile telephone, comprising: a navigation apparatus for an automobile; a building database; a plurality of directional antennas; and an antenna directivity control apparatus for controlling said directional antenna. Gets information about multipath environments the navigation device and the serving base station and the mobile station by the building database, predicting a plurality of main wave arrival direction from the acquired information, the by the antenna directivity control apparatus
The predicted directivity of a plurality of directional antennas
By pointing each to the main wave arrival direction,
A diversity receiver for a mobile phone, characterized in that the quality of each received signal of the directional antenna is improved.