JPH11331171A - Radio communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit and receive high-speed data of an image, etc., in a train such as the Shinkansen (Bullet train) by selecting a signal of a maximum level from the output signal of a receiving means connected to plural directional antennas arranged so as to differentiate directivity and protocol-converting the signal of the maximum level for relaying to a local area network arranged in a traveling body. SOLUTION: A high-speed signal, such as image data transmitted from the fixed station of a portable telephone system, is received by eight first antennas 11a to 11h and first RF parts 12a to 12h with a directivity pattern and converted to digital signal by first A/D/A converting parts 14a to 14h. A digital signal processing part 13 demodulates the digital signal by a digital transmission and reception/buffer part 131, selects a signal of the maximum level from plural demodulated signals by a beam selecting part 132, and executes protocol conversion for an intra-train radio local area network by an adaptive signal processing part 133 for transmitting via second antennas 15a to 15n (n is the number of vehicles).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication device, and more particularly to a local area network mounted on a mobile body such as a Shinkansen to transmit and receive high-speed and large-capacity data such as images and arranged on the mobile body. , Below L
AN)).

[0002]

2. Description of the Related Art Conventionally, trains such as Shinkansen trains have been provided with a 400 MHz band wireless telephone device for business communication or public communication. This radio telephone adopts a mobile communication system in which a user in a train and a communication partner outside the train communicate with each other via a number of fixed base stations arranged along the railway. The detailed description is omitted in the document "Handbook of Antenna Engineering" edited by the Institute of Electronics and Communication Engineers, page 317, Ohmsha, 1989, but the antenna used for this wireless telephone device is A Yagi-Uda antenna having a directional pattern for communication with a fixed base station arranged at a predetermined location and having a directional pattern for reducing echo distortion due to multiple reflection is employed.

On the other hand, in recent years, in mobile communication represented by a mobile phone widely used in society, not only a voice call but also a data communication service for transmitting digital information is provided. Services for transmitting data are also planned.

FIG. 3 is a conceptual diagram showing a usage form of a digital cellular type PDC (Personal Digital Cellular) which is a typical portable telephone system. As is well known, a digital cellular PDC covers a service area by a plurality of cells, and each cell includes a fixed station 32 covering the cell 31 and a fixed station 32 disposed in the cell 31 as shown in FIG. Mobile stations 33a, 33b, and 33c passing through the network, and in order to increase the number of users who can talk at the same time, time division multiple access (T
ime Division Multiple Access (hereinafter referred to as TDMA). In the TDMA system, the time axis of a transmission / reception signal is divided and assigned to each user so that a certain assigned frequency band is shared by a plurality of users.

[0005] That is, the fixed station 32 is the mobile station 33a, 3 in the cell 31.
When the above TDMA signal is transmitted to 3b, 33c, mobile stations 33a, 33
Each of b and 33c receives the signal of the time slot allocated to its own station and periodically transmits a burst signal (a signal with a high transmission speed) to the fixed station 32. In the example shown in FIG. 3, the first, second, and third time slots are assigned to the mobile stations 33a, 33b, and 33c, respectively, and the mobile station 33a, 33b, and 33c perform transmission and reception with the fixed station 32 in the own station time slot.

Normally, in the above-mentioned portable telephone system, a signal having a transmission speed of 9.6 kbps to 32 kbps is used. However, since image data transmission planned in the future transmits large-capacity data, this data must be transmitted in a short time. Number to transmit
Transmission of high-speed signals of Mbps or more is required.

Here, C / N (Carrier / Noise) at the time of signal reception, which is a problem when transmitting the high-speed signal of several Mbps or more, is described.
The characteristic deterioration will be described. In general, when the transmission speed of a signal increases, the signal period becomes shorter, so that the frequency component (frequency band) of the signal becomes wider. Therefore, in order to transmit a high-speed signal, a wide band that allows all frequency components of the signal to pass is required, and along with this, noise passes through this wide signal band, so that the noise level (N) increases. Reception C / N characteristics are reduced, and as a result, communication quality is degraded. In order to improve the C / N characteristic deterioration, the received signal level (C) may be increased without increasing the noise level (N), and the received signal level is usually increased by using a directional antenna having a high gain. A method of increasing the size is adopted.

[0008] Since the current mobile phone terminal needs to receive a signal arriving from an arbitrary direction, it uses an omni-directional antenna having a low gain (basically 0 dBi). It is impossible to receive high-speed signals of several Mbps or more because of the decrease.

By the way, in view of the development of mobile communication such as the above-mentioned portable telephone system, communication on a train such as the above-mentioned Shinkansen, especially public communication, requires a user terminal and a train on the train from the viewpoint of communication cost. There is a demand for a communication device that can be connected to an external digital cellular mobile phone system or the like to transmit and receive not only voice calls but also high-speed and large-volume data such as images.

[0010]

However, the user in the train connects to the existing mobile phone system using the wireless communication (wireless telephone) device of the conventional Shinkansen train described above,
When transmitting and receiving high-speed large-capacity data such as images, there are the following problems. In other words, the antenna used in this wireless communication device has a directional pattern covering a specific direction since the purpose is to communicate with a fixed base station arranged at a predetermined position (direction) along the railway. However,
Since a fixed station for a mobile phone such as a digital cellular system is installed irrespective of the route of the train (Shinkansen), the level of the directivity pattern is almost null depending on the positional relationship between the train and the fixed station. Is sometimes used,
As a result, there occurs a problem that the reception signal level is reduced and the communication is interrupted. Also, if an antenna having an omni-directional pattern is used for this problem, it is not possible to improve the C / N characteristic deterioration of the received signal in high-speed large-capacity data transmission such as an image for the above-described reason. As a result, transmission of a high-speed signal is impossible as a result. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems related to the conventional wireless communication device. In a train such as a bullet train, not only a voice call but also a high-speed data such as an image.
It is an object of the present invention to provide a wireless communication device capable of transmitting and receiving (signals).

[0011]

According to one aspect of the present invention, there is provided a wireless communication apparatus according to the present invention, which is a wireless communication apparatus mounted on a mobile body, and each of which has a directional direction. Including a plurality of directional antennas arranged differently and receiving means connected to each antenna, selecting a maximum level signal from an output signal of the receiving means, and performing protocol conversion on the selected maximum level signal To a local area network located in the moving object. The wireless communication device according to claim 2 of the present invention is the wireless communication device according to claim 1, wherein the protocol conversion converts the selected maximum level signal into a low-speed signal of a predetermined transmission rate or less. Including.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 1 is a functional block diagram showing an embodiment of a wireless communication device according to the present invention. The wireless communication device 10 shown in this example has beam half-value angles arranged on the train roof to cover all azimuth angles.
Eight first antennas 11a, 11b,... 11h having a directional pattern of about 45 degrees (gain of about 11 dBi), and separation and amplification of transmission / reception signals, amplification, frequency conversion, etc. Via the first A / D / A converters 14a, 14b,... 14h connected to the antennas 11a, 11b,... 11h and converting analog signals (digital signals) into digital signals (analog signals). To supply a predetermined high-speed transmission / reception signal to the digital signal processing unit 13
The first RF units 12a, 12b,... 12h cover the respective vehicles arranged inside the respective vehicles for the wireless LAN in the train for performing processing such as separation, amplification, frequency conversion and the like of transmission / reception signals.
2n antennas 15a, 15b, ... 15n (n is the number of vehicles) and convert analog signals (digital signals) to digital signals
(Analog signal) to convert the second A / D / A converter 17a, 17b,
.. The second RF units 16a and 16 for supplying transmission / reception signals having a predetermined transmission rate to the digital signal processing unit 13 via 17n
b,... 16h. The beam half-value angle 4
First antenna 11a, 1 having a directional pattern of about 5 degrees
A general horn antenna is used as 1b,..., 11h.

The digital signal processing unit 13 includes a digital transmission / reception / buffer unit 131 capable of storing modulation / demodulation processing and transmission / reception signals as necessary, and the first antennas 11a, 11b,. A beam selector 132 for selecting a signal having the maximum level from the signals received via the interface, and an adaptive signal processor 133 for performing protocol conversion of transmission data such as a transmission data rate.

The wireless communication apparatus according to the present invention shown in FIG. 1 functions as follows. That is, digital cellular system
Eight high-speed signals such as image data (or conventional low-speed signals of 32 kbps or less) transmitted at a transmission speed of several Mbps or more from a mobile phone system fixed station such as a PDC have eight directivity patterns each having a high gain. First antennas 11a, 11b,... 1
When the first RF units 12a, 12b, ... 12h receive via 1h,
This is amplified and supplied to the first A / D / A converters 14a, 14b,... 14h, where the analog signal is converted into a digital signal and output to the digital signal processor 13.

The digital signal processing unit 13 performs digital transmission and reception
The signal is demodulated in the buffer unit 131 and the beam selecting unit 132 selects the signal of the maximum level from the plurality of demodulated signals, and the adaptive signal processing unit 133 transmits the signal to the in-train wireless LAN that performs low-speed data transmission described later. The protocol conversion of the necessary transmission signal such as the signal transmission speed to supply the data is performed.

The function of the radio communication apparatus according to the present invention when receiving a signal from outside the train has been described above. However, when transmitting a signal to outside the train, a predetermined modulation operation performed instead of the demodulation operation is described. Since the description becomes complicated, the description is omitted.

Here, a usage form of the in-train wireless LAN will be described. FIG. 2 is a conceptual diagram showing a configuration of a wireless LAN in a train. In the train 21, each user uses a communication terminal 20 (for example, a card-type wireless LAN adapter 23 attached to a portable personal computer 22) as a LAN terminal. As described above, it is assumed that the functions used by the terminals used by each user are not so high.
Performs low-speed transmission of about 8.8kbps. As described above, each vehicle has a second antenna 15a covering each vehicle,
15n are arranged, so that transmission / reception signals between the user terminal 20 and the wireless communication device 10 according to the present invention are
It can be transmitted via two antennas 15a, 15b,... 15n.

As described above, since the radio communication apparatus according to the present invention functions, a high-speed signal arriving from outside the train in any direction can be received via an antenna having a high-gain directivity pattern. C / N associated with transmission
The communication quality can be improved by preventing the deterioration of the characteristics, so that high-speed signals such as image data can be received, and the high-speed signals are transmitted to train users via a wireless LAN disposed in the train. Information can be transmitted.

The second antennas 15a, 15b,.
..If a directional antenna having a predetermined gain is used as 15n, and a train user uses a terminal capable of high-speed transmission of several Mbps or more, a high-speed signal such as image data can be transmitted from the train user. Can be transmitted to a mobile phone system outside the train.

The first antennas 11a, 11b,.
・ ・ For 11h, instead of horn antenna, for example,
A plurality of microstrip antennas (planar antennas) may be used, and if they are attached to the vehicle to cover all azimuth angles, there is no problem in appearance, but rather an arbitrary directivity pattern by arraying. (Antenna gain) can be obtained, and the degree of freedom in design is increased.

Further, the first antennas 11a, 11b,... 11h
Instead of preparing a plurality of fixed beams, one directional pattern may be scanned in the azimuthal direction as in a phased array antenna.

[0022]

As described above, according to the present invention, a plurality of directional patterns are arranged on the outer wall of a train so as to cover all azimuth angles, and a high-speed signal arriving from outside the train is received and adaptive signal processing is performed. Since the communication unit is configured to convert the protocol and connect to the in-train LAN, it is very effective in realizing a wireless communication device that enables passengers in the train to transmit and receive high-speed signals such as image data.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of a wireless communication apparatus according to the present invention.

FIG. 2 is a conceptual diagram showing a configuration example of a wireless LAN in a train.

FIG. 3 is a conceptual diagram showing a usage form of a digital cellular type PDC mobile phone system.

[Explanation of symbols]

, Wireless communication devices 11a, 11b, ..., 11h ... first antennas 12a, 12b, ..., 12h having directivity patterns first RF unit 13, digital signal processing unit 14a , 14b, ..., 14h ... first A / D / A converters 15a, 15b, ..., 15n ... second antennas for wireless LAN in trains 16a, 16b, ..., 16n 2nd RF section 17a, 17b, ..., 17n2nd A / D / A conversion section 131Digital transmission / reception / buffer section132 Beam selection section133Adaptive signal processing section

Claims (2)

[Claims] 1. A wireless communication device mounted on a mobile object, comprising: a plurality of directional antennas arranged so as to have different directivity directions; and receiving means connected to each antenna, and an output of said receiving means. A radio communication apparatus comprising: selecting a signal of a maximum level from signals; converting the selected signal of the maximum level into a protocol; and relaying the protocol to a local area network disposed in the mobile object. 2. The wireless communication apparatus according to claim 1, wherein said protocol conversion includes converting said selected maximum-level signal into a low-speed signal having a predetermined transmission rate or less.