JPH02268528A - Receiver for vehicle - Google Patents

Abstract

PURPOSE:To prevent a code error rate from deteriorating and to improve communication quality by specifying a managing base station corresponding to the position of its own vehicle by using the map of a base station and city structural data, and switching a wave receiving with a directional antenna to a direct wave and a reflected wave appropriately. CONSTITUTION:The directional antenna A, an its own vehicle position detecting means B to detect the geographical position of its own vehicle, a base station map memory C to store the geographical position of the base station, and a base station specifying means D to specify the position of the managing base station from the geographical positions of its own vehicle and the base station are provided. Also, a city structural data memory E, an error detecting part F, a reflected wave arrival direction prediction means G, and an antenna direction change means H are provided. The positions of its own vehicle and the managing base station are detected, and the arrival direction of the reflected wave is predicted by those positions and the city structural data, and the direction of the directional antenna A is set toward the arrival direction of the direct wave or that of the reflected wave. In such a way, it is possible to effectively obtain a reception wave with high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle receiving device for performing digital mobile communications in urban areas.

[Conventional technology] With the dramatic progress in telecommunications technology in recent years, communication equipment has become smaller and more sophisticated, and moving objects such as vehicles are now equipped with various communication equipment. .

In particular, there is a strong demand for car phones in urban areas.
With the development of base stations, car telephones are becoming widely used.

In such mobile (vehicle) communications such as car telephones, digital communications, in which information is digitized and communicated, are becoming widespread. According to this digital communication, it is possible not only to communicate simple voice signals such as a car phone, but also to carry out data communication with a host computer by installing a terminal device on a mobile body.

The most important thing in mobile communications is how to receive high-quality radio waves. That is,
A mobile object changes its position, and the relative positional relationship between the base station and the mobile object always changes. In addition, received waves are greatly affected by the condition of buildings around the mobile object, making it extremely difficult to maintain good transmission and reception.

Therefore, there is a diversity reception system as a system that constantly detects the condition of the received waves, which changes greatly as the vehicle moves, and performs optimal reception. This diversity reception system is a system in which, for example, a plurality of antennas are installed in a vehicle, the intensities of received radio waves from the plurality of antennas are compared, and the one with the highest intensity is adopted.

By using this diversity reception system,
It is possible to perform reception according to the surrounding situation, and it is possible to improve the reception quality of the vehicle receiving device.

Such a diversity receiving device for a vehicle is disclosed in, for example, Japanese Patent Laid-Open No. 168442/1983. In the device disclosed in this publication, it is determined in which of the regions divided by a plurality of predetermined values the intensities of radio waves received by a plurality of antennas are located. Then, when the antenna moves out of this area, the antenna is switched.

Therefore, multipath noise caused by the reflection of short-term radio waves that should not be used can be removed.

In other words, according to the diversity reception system, the antenna with the highest reception strength is always used, but if multipath noise occurs due to short-term reflected waves, the antenna will be switched too frequently, which will actually impair reception performance. It will deteriorate. However, according to the receiving device described in the above-mentioned publication, since a predetermined area is set, the antenna can be switched closer to the desired one, and multipath noise can be removed.

On the other hand, in antennas for receiving satellite broadcasting, a system is widely used in which an antenna with very high directivity is used and the antenna is always kept in the direction of the transmitting station. This is because if the location of the transmitting station is known, the directivity of the antenna can always be kept in the direction of the transmitting station, which is thought to allow optimal reception.

[Problem to be solved by the invention] However, under complex multi-wave propagation conditions in urban areas, the reflected waves that are reflected by buildings etc. and reach the vehicle are stronger than the direct waves that go directly from the transmitting station to the vehicle. Cases in which the intensity is strong often occur, and there are many cases where the reflected wave should be received.

In such a case, if the directivity of the antenna remains directed to the direction of the wave (toward the transmitting station), the quality of the received signal will deteriorate due to a drop in the reception level.

In particular, in digital transmission, the error rate deteriorates, making it impossible to perform normal reception.

On the other hand, as in the above-mentioned diversity reception system, if it is determined whether to use a direct wave or a reflected wave only based on the magnitude of the reception level, the reception quality may actually deteriorate. That is, even if the intensity level of the received signal is high, the error rate may increase due to the influence of reflection.

The present invention has been made to solve the above-mentioned problems, and when the quality of the received signal deteriorates, the direction of the antenna is directed to the reflected wave, so that the digital communication signal can always be effectively transmitted. An object of the present invention is to provide a vehicle receiving device that can perform reception.

[Means for Solving the Problems] As shown in FIG. 1, the vehicle receiving device according to the present invention uses a directional antenna ( A) and vehicle position detection means (B) for detecting the geographical location of the vehicle
, a base station map memory (C) that stores the geographical location of the base station, a base station identification means (D) that identifies the location of the base station in charge based on the geographical location of the own vehicle and the base station, and an urban area where the vehicle is traveling. an urban structure data memory (E) that stores urban structure data such as the layout and height of buildings; and an error detection section (F) that detects error conditions in the received signal from error detection codes included in the received signal. , a reflected wave arrival direction prediction means (G) that predicts the arrival direction of the reflected wave from the own vehicle position, the jurisdiction base station position, and urban structure data when the error situation worsens; The present invention is characterized by comprising antenna pointing direction changing means (H) for changing the pointing direction of the directional antenna (A) so as to direct the pointing direction of the antenna.

[Operation] The vehicle receiving device according to the present invention has the above-described configuration, and can detect the own vehicle position and the position of the base station in charge, and can detect the direction of arrival of reflected waves based on this and the urban structure data. can be predicted.

On the other hand, since the number of errors is detected using an error detection code included in the received signal, if this error occurs, it is possible to direct the directional antenna to the direction of arrival of reflected waves (or direction of arrival of direct waves). can. Therefore, when the number of errors increases and the quality of the received signal deteriorates, the directional antenna can be accurately directed to the direction in which radio waves arrive directly or the direction in which reflected waves arrive. Therefore, high quality received waves can be effectively obtained.

[Embodiment] Hereinafter, an embodiment of a vehicle receiving device according to the present invention will be described based on the drawings.

FIG. 2 is a block diagram showing the overall configuration of the embodiment,
installed on the vehicle. In the figure, directional antenna 1
0 receives radio waves transmitted from the base station and supplies them to the receiving unit 12. Here, in order to efficiently receive radio waves only in a predetermined direction, the directional antenna 10 needs to be oriented in the direction in which the radio waves arrive. When the antenna is directed in the direction in which radio waves arrive, extremely high quality reception can be achieved. However, the direction in which the radio waves arrive changes every moment as the vehicle moves. Therefore, in order to cope with this, the directional antenna 10 is rotatably attached to the antenna raw data 14. That is, the directional antenna 10 is rotated by the antenna raw data 14 and directed in a predetermined direction. Note that the antenna raw data 14 can be configured using a stepping motor or the like.

The receiving unit 12 detects the received signal received by the directional antenna 10 and demodulates the received signal into digital data. This demodulated data is then sent to a CPU (not shown), where it undergoes predetermined processing. In this embodiment, an error detection section 16 detects errors in the received signal.

This error detection code is performed using an error code included in the received signal. The error detection unit 16 then supplies the number of errors e to the arithmetic control unit (ECU) 18.

On the other hand, in this embodiment, the vehicle has three sensors: a geomagnetic sensor 22, a speed sensor 24, and a position sensor 26. The geomagnetic sensor 22 is a sensor that detects the orientation of the vehicle by detecting the geomagnetism, and includes an excitation winding wound around an annular permalloy, which is usually a ferromagnetic material, and an excitation winding wound perpendicularly to each other in the diametrical direction of the permalloy. It consists of two detection windings. Then, an alternating current voltage is applied to the excitation winding, and the two voltages are summed Δp to the detection winding, thereby detecting the direction (azimuth) of the vehicle with respect to the earth's magnetism.

Therefore, the direction in which the vehicle is traveling can be determined by the geomagnetic sensor 22.

The speed sensor 24 is attached to a transmission or the like, and detects the speed of the vehicle by detecting the number of rotations of a rotating plate that rotates in accordance with the wheels.

Further, the position detection sensor 26 is formed by a GPS, a beacon receiver, or the like. GPS (Global Positioning System) measures the latitude and longitude of a vehicle by receiving radio waves from multiple (at least three) satellites orbiting the earth and measuring the propagation time of these radio waves. be. Furthermore, the beacon receiver receives a signal from a road beacon that is installed at a predetermined reference position on the road and transmits a position signal, and thereby determines the position of the vehicle. Based on these, own vehicle position (x n
+ y n ) is detected. Note that when beacon reception blocks are used, the own vehicle position data is constantly updated based on the driving direction, vehicle speed, and driving time in locations where road beacons are not installed.

Here, the vehicle receiving apparatus of this embodiment has a base station map memory 30 and an urban structure data memory 32.

Then, the ECUlg can specify the base station under its jurisdiction according to the own vehicle position (x n, y n) from the position detection sensor 26, and determine the position (x
1. y 1) can be known.

Therefore, ECUlg is the own vehicle position (x n, y n)
From this and the base station position (x 1. V 1), the relative positional relationship between the two can be grasped, and the orientation θd can be calculated. Therefore, the ECUlg is set so that the directional antenna 10 faces in the direction of the base station.
is supplied to the antenna raw data 14 as an operation signal.

In this way, the ECUlg can always recognize the direction of the base station when the vehicle is running, and controls the antenna raw data 14 accordingly, so that the directional antenna 10 always has directivity in the direction of the base station. It will be directed towards.

Therefore, direct waves from the base station can be captured at all times.

The urban structure data memory 32 stores data related to the urban structure, such as the height and layout of buildings and road widths in the area where the vehicle travels. Then, own vehicle position (x n,
y n) and base station location (Xl.

yl), and data f(x, y) such as the height of the building and the width of the road between the own vehicle and the base station from the urban structure data memory 32.
The direction of arrival of the reflected wave is calculated from

Regarding this calculation method, please refer to “Radio Research Institute Quarterly Report” p. 43.
~54.1987.12, etc., so a detailed explanation will be omitted, but the multiple wave propagation structure in the city is described in the second
This is determined by a simple geometrical optical mode as shown in the figure, and the direction θU of the reflected wave is calculated.

In this way, the ECUlg can refer to the data f (x, y) from the urban structure data memory 32 and know the arrival direction θU of the reflected wave.

Therefore, the ECUlg can send an operation signal regarding the reflected wave arrival direction θU to the antenna raw data 14,
By operating the antenna raw data 14 accordingly, the directional antenna 10 can be directed toward the reflected wave.

Next, the operation of the vehicle receiving apparatus according to the present invention will be explained based on FIG.

First, ECUlg contains vehicle speed information v from the speed sensor 24, vehicle traveling direction ψ from the geomagnetic sensor 22, and position information from the position detection sensor 26 such as a beacon receiver (
x n, y n) (step 1). Then, from this information, the current vehicle position (x O, y O)
Calculate. That is, the vehicle speed V is decomposed into speeds in the X direction and the X direction on the map according to the vehicle traveling direction ψ, and this is multiplied by the travel time Δt to calculate the travel distances in the X direction and the X direction. Then, the current vehicle position (x O, y O) is calculated by adding the travel distances in the X direction and the X direction to the position information (x n, y n) for each reference position detected by the position detection sensor 26. (Step 2).

Next, the base station in charge is specified from the base station position information from the base station map memory 30 and the vehicle position (xO, yO), and its geographical position (x1.y1) is read (step 3). .

Then, the direct wave direction θd from the base station to the host vehicle is calculated from the current vehicle position (x O, y O) and the base station position (x 1. V 1) using the following equation (step 4).

θda-tan″″’ ((yl-yO)/(xi-x
O)) Next, the antenna raw data 14 is controlled based on the direct wave arrival direction θd calculated in this way, and the directional antenna 10 is directed toward the direct wave arrival direction.

Therefore, the direction of the directional antenna 10 changes as the vehicle travels, and can always receive direct waves.

The ECUlg also detects the number of errors e from the error detection unit 16 (step 5). Then, it is determined whether the number e of error detections is larger than a predetermined value (step 7). In this example, it is determined whether the number of errors e is 1 or more, and the number of errors e is
If is less than 1, the process returns to step 1 and the control is repeated so that the directional antenna 10 is directed directly to the wave direction θd. Note that in this example, from step 7 to step 1
A determination is made as to whether or not to execute the process on the route returning to (step 8). Then, if the processing is not to be continued, the control is ended.

On the other hand, if the number of errors e is 1 or more, it is determined that the quality of the direct wave is poor and it is better to switch the received signal to the reflected wave. Therefore, in order to direct the directional antenna 10 in the direction in which the reflected waves arrive, the following operation is performed.

First, urban structure data f (x, y) between the base station and the vehicle is read from the urban structure data memory 32 (step 9). That is, urban structure data f (x, y
).

Then, the reflected wave arrival direction θU is calculated (step 10). Calculation of this reflected wave arrival direction θU is performed using the base station position (xi, x2) and the vehicle position (x O, x
The direction of arrival θU of the reflected wave is calculated from the urban structure data f(x, y) by electronic computer simulation using geometric optics mode. This calculation is conveniently shown as follows.

θu-g ((xO, yO), (xi, yl).

f (x, y)1 Then, when the reflected wave arrival direction θU is calculated in this way, the ECU 18 outputs this to the antenna rotor 14, and the directional antenna 10 receives the reflected wave arrival direction θU in the force direction. (Step 11).

Then, the number of errors e is detected with the directional antenna 10 directed in the direction in which the reflected waves arrive (step 12). Note that in order to operate the antenna rotator 14 to direct the directional antenna 10 in the direction of arrival of the reflected wave θU, it is often necessary for a predetermined period of time to elapse; It is good to provide a process of waiting.

Next, it is determined whether the number of errors e in receiving the reflected wave is 1 or more (step 13). If the number of errors e in receiving the reflected wave is 0, it is determined that it is appropriate to receive the reflected wave, and the process returns to step 9, where the reflected wave arrival direction θU is calculated and the θU force direction is adjusted. Repeat driving the antenna.

On the other hand, if the number of errors e in reflected wave reception is 1 or more, it is determined that reflected wave reception is not suitable, and the process returns to step 1 to proceed to direct wave reception.

In this way, when the number of errors e is greater than a predetermined amount, reflected wave reception and direct wave reception are alternately changed, and optimal digital data reception can be performed at all times.

In this way, according to this embodiment, the directivity of the antenna is normally directed toward the base station side (direct wave reception), but when the error rate in error code detection deteriorates, the directionality of the antenna is directed toward the base station side (direct wave reception). Directivity is directed toward the direction of arrival of reflected waves based on the urban propagation model. Therefore, it is possible to prevent deterioration of the code error rate, improve communication quality, reduce the number of retransmissions due to code errors in packet communication, etc., and shorten communication time.

[Effects of the Invention] As explained above, according to the vehicle receiving device according to the present invention, the radio waves received by the directional antenna can be appropriately switched between direct waves and reflected waves, thereby preventing deterioration of the bit error rate. This makes it possible to improve communication quality.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the overall configuration of a vehicle receiving device according to the present invention, Fig. 2 is a block diagram showing the overall configuration of an embodiment, and Fig. 3 shows the arrival of reflected waves in the geometric optical mode in the same embodiment. FIG. 4 is a flowchart showing the operation of the ECU 18 in the same embodiment. 10 ... Directional antenna 22 ... Geomagnetic sensor 26 ... Position detection sensor (vehicle position detection means) 1
8... ECU (arithmetic control unit) 30... Base station map memory Urban structure data memory Error detection unit Antenna low data (antenna orientation direction changing means)

Claims (1)

[Claims] (1) A directional antenna having directivity in reception characteristics for receiving digital communication signals transmitted from a base station; a vehicle position detection means for detecting the geographical position of the vehicle; and a vehicle position detecting means for detecting the geographical position of the base station. A base station map memory for storing base station map memory, a base station identification means for identifying the location of the base station in charge based on the geographical location of the own vehicle and the base station, and urban structure data such as the layout and height of buildings in the urban area where the vehicle is traveling. an error detection unit that detects error conditions in the received signal from error detection codes included in the received signal;
reflected wave arrival direction prediction means for predicting the arrival direction of reflected waves from urban structure data; and an antenna that changes the pointing direction of the directional antenna so that the pointing direction of the directional antenna is directed to the predicted reflected wave arrival direction. A receiving device for a vehicle, comprising: directivity direction changing means.