Abstract:
This invention provides a vehicle compartment radio LAN system for communicating with a terminal installed in a vehicle compartment through a repeater, wherein a repeater is provided in front of each seat row. Thus, a terminal installed in a front seat communicates by radio through a repeater, a terminal installed in a second seat communicates by radio through another repeater and a terminal installed in a third seat communicates by radio through still another repeater.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims benefit of priority under 35 U.S.C. § 119 to Japanese Patent Application No.2000-35589, filed on Feb. 14, 2000, the entire contents of which are incorporated by reference herein.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a vehicle compartment radio LAN system and more particularly to a vehicle compartment radio LAN system which enables communication between terminals provided on different seat rows by providing each seat row with a repeater.  
           [0004]    2. Description of the Related Art  
           [0005]    In a conventional vehicle compartment radio LAN system, a radio terminal is mounted in front of a front seat such as dash board so as to communicate with another terminal installed in a front seat by radio.  
           [0006]    In a conventional radio LAN system in office room or the like, as shown in FIG. 1, repeaters  102   a,    102   b,    102   c  connected to a wired LAN  101  are mounted on the ceiling, so that terminals  103   a,    103   b,    103   c  communicate with the repeaters mounted vertically above them. That is, it is so constructed that the terminal  103   a  communicates with the repeater  102   a,  the terminal  103   b  communicates with the repeater  102   b  and the terminal  103   c  communicates with the repeater  102   c.    
           [0007]    However, if the radio terminal is just mounted in front of the front seat like in the aforementioned conventional radio LAN system, the seats turn to a shielding object. As a result, a terminal brought into a second seat or third seat cannot communicate with the terminal in front of the front seat, which is a conventional problem to be solved.  
           [0008]    Further, there is another problem that radio communication cannot be carried out between terminals in each seat row, such as in the gap between the front seat and the second seat or in the gap between the second and the third seat.  
           [0009]    In the indoor radio LAN system, a sufficient space can be secured vertically above the terminal like in office, so that there is no possibility that any shielding object may enter between the repeater and terminal. Therefore, radio communication is secured continuously in an environment in which the terminal or shielding object is semi-fixed. However, there is such a problem that radio communication cannot be carried out continuously between the terminal and repeater under such an environment in which the terminal and shielding object may be moved as vehicle compartment and factory.  
         SUMMARY OF THE INVENTION  
         [0010]    Accordingly, the present invention has been achieved in views of the above described problems and therefore, an object of the invention is to provide a vehicle compartment radio LAN system allowing communication between terminals installed in different seat rows and further allowing continuous communication even under such an environment in which no sufficient space can be secured and a terminal or a shielding object may be moved as a vehicle compartment.  
           [0011]    To achieve the above object, according to an aspect of the present invention, there is provided a vehicle compartment radio LAN system for communicating with a terminal installed in vehicle compartment through a repeater by radio wherein each repeater is mounted in front of each seat row.  
           [0012]    According to the present invention, communication is enabled between terminals installed in different seat rows.  
           [0013]    Further, according to another aspect of the present invention, there is provided a vehicle compartment radio LAN system for communicating with a terminal installed in vehicle compartment through a repeater by radio wherein plural repeaters are mounted for each seat row at a position allowing radio communication with a terminal installed in each seat row and radio communication is carried out by selecting a repeater securing an optimum communication state from the plural repeaters.  
           [0014]    According to the present invention, continuous radio communication is allowed even under such an environment in which no sufficient space can be secured and a terminal or shielding object may be moved as the vehicle compartment.  
           [0015]    The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    In the accompanying drawings:  
         [0017]    [0017]FIG. 1 is a diagram for explaining a conventional indoor radio LAN system;  
         [0018]    [0018]FIG. 2 is a perspective view showing a first installation example of a first embodiment of a vehicle compartment radio LAN system of the present invention;  
         [0019]    [0019]FIGS. 3A, 3B are a side view and a plan view of the first installation example of the first embodiment of the vehicle compartment radio LAN system of the present invention;  
         [0020]    [0020]FIG. 4 is a diagram for explaining communication by a repeater in the vehicle compartment radio LAN system shown in FIG. 2;  
         [0021]    [0021]FIG. 5 is a perspective view showing a second installation example of the first embodiment of the vehicle compartment radio LAN system of the present invention;  
         [0022]    [0022]FIG. 6 is a perspective view showing a third installation example of the first embodiment of the vehicle compartment radio LAN system of the present invention;  
         [0023]    [0023]FIG. 7 is a diagram for explaining communication by a repeater in the vehicle compartment radio LAN system shown in FIGS. 5, 6;  
         [0024]    [0024]FIG. 8 is a perspective view showing a structure of a second embodiment of the vehicle compartment radio LAN system of the present invention;  
         [0025]    [0025]FIG. 9 is a diagram for explaining a structure of the repeater shown in FIG. 8;  
         [0026]    [0026]FIG. 10 is a perspective view showing a first installation example of the second embodiment of the vehicle compartment radio LAN system of the present invention;  
         [0027]    [0027]FIG. 11 is a diagram for explaining communication by a repeater in the vehicle compartment radio LAN system shown in FIG. 10;  
         [0028]    [0028]FIG. 12 is a perspective view showing a second installation example of the second embodiment of the vehicle compartment radio LAN system of the present invention;  
         [0029]    [0029]FIG. 13 is a perspective view showing a third installation example of the second embodiment of the vehicle compartment radio LAN system of the present invention; and  
         [0030]    [0030]FIG. 14 is a diagram for explaining communication by a repeater in the vehicle compartment radio LAN system shown in FIG. 13.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    Hereinafter, an example of installation of the repeater according to the vehicle compartment radio LAN system of the first embodiment will be described with reference to the accompanying drawings.  
         [0032]    [0032]FIG. 2 is a perspective view showing a first installation example. FIGS. 3A, 3B are a side view and a plan view of the first installation example. As shown in FIG. 2 and FIGS. 3A, 3B, a repeater R 1  is mounted on a dash board in front of the front seat. A repeater R 2  is mounted on the back of the front seat (the driver&#39;s seat in FIG. 2) just in front of a second seat and a repeater R 3  is mounted on the back of the second seat just in front of a third seat.  
         [0033]    Therefore, as shown in FIG. 4, a terminal installed in the front seat is capable of communicating with the repeater R 1  and a terminal installed in the second seat is capable of communicating with the repeater R 2 . Further, a terminal installed in the third seat is capable of communicating with the repeater R 3 .  
         [0034]    [0034]FIG. 5 is a perspective view showing a second installation example. As shown in FIG. 5, the repeater R 1  is mounted on the dash board in front of the front seat, the repeater R 2  is mounted on a ceiling in front of the second seat and the repeater R 3  is mounted on the ceiling in front of the third seat.  
         [0035]    Further, FIG. 6 is a perspective view showing a third installation example. As shown in FIG. 6, the repeater R 1  is mounted on a front pillar in front of the front seat, the repeater R 2  is mounted on a front end of a drip line in front of the second seat and the repeater R 3  is mounted on a rear end of the drip line in front of the third seat.  
         [0036]    In the second and third installation examples, as shown in FIG. 7, a terminal placed on the front seat is capable of communicating with the repeater R 1 , a terminal placed on the second seat is capable of communicating with the repeater R 2  and a terminal placed on the third seat is capable of communicating with the repeater R 3 .  
         [0037]    Because as shown in each installation example described above, the repeater is mounted in front of each seat, the repeater is never shielded by any seat so that it is capable of communicating with a terminal brought into any seat row. Further, terminals existing in different seat rows are capable of communicating with each other.  
         [0038]    Further, by installing the repeater R 1  in front of the front seat, the repeater R 1  is capable of communicating with a navigation system, audio system or the like (not shown) mounted on console easily. By mounting the repeater R 3  in front of the third seat, the repeater R 3  is capable of communicating with a back camera (not shown) provided on a rear portion of a vehicle. Further, the repeater may be connected to a CD changer, DVD changer, digital TV monitor or the like (not shown) provided in trunk through wire so that it is capable of communicating therewith.  
         [0039]    In the above described installation examples, it is assumed that the repeaters R 1 , R 2 , R 3  are mounted in such a manner that they are capable of communicating with each other securely irrespective of radio communication or wired communication. Further, the quantity of the repeaters is not limited to three, but may be increased as the quantity of seat rows is increased like in bus. Conversely, the quantity of the repeaters may be decreased if that of the seat rows is decreased.  
         [0040]    Further, although in the above described installation example, the repeater R 1  is mounted on the dash board or front pillar in front of the front seat, it is not restricted to these positions, but the repeater may be mounted on any place in front of the front seat such as rearview mirror and console if it is capable of communicating by radio.  
         [0041]    Likewise, the repeaters R 2 , R 3  may be also mounted at any place in front of the second seat and third seat respectively if each of them is capable of communicating by radio. For example, they may be mounted on a bottom of each of the second seat and third seat, floor or the like.  
         [0042]    Further, the installation examples shown in FIGS. 2, 5,  6  may be combined with each other.  
         [0043]    Although the first embodiment has been described about a case where the repeaters are mounted on a vehicle, this embodiment may be applied to conveyance having seats such as airplane and ship.  
         [0044]    Next, a vehicle compartment radio LAN system of a second embodiment will be described with reference to FIG. 8.  
         [0045]    As shown in FIG. 8, the vehicle compartment radio LAN system  1  of this embodiment is comprised of plural repeaters R 1 , R 2 , R 3 , which communicate by radio with plural terminals (N 1 , . . . N 7 ) installed in or brought into the vehicle compartment.  
         [0046]    The vehicle compartment radio LAN system  1  shown in FIG. 8 is indicated about a case where the three repeaters R 1 , R 2 , R 3  are provided. These repeaters R 1 , R 2 , R 3  cover all region having a possibility that any terminal may exist and are installed at each position having a lowest possibility that electronic wave sent from the terminal may be interrupted. Further, it is assumed that the repeaters R 1 , R 2 , R 3  are mounted in such a manner capable of communicating securely irrespective of radio communication or wired communication and the repeater R 1  is connected to the wired LAN  2 .  
         [0047]    The vehicle compartment radio LAN system does not communicate with a repeater located most nearby but selects a repeater securing an optimum communication state from plural repeaters.  
         [0048]    For example, FIG. 8 indicates a case where seven terminals are available. Although terminals N 4 , N 5 , N 6 , N 7  communicate with repeaters R 3 , R 1 , R 2 , R 3  located most nearby respectively, terminals N 1 , N 2 , N 3  do not communicate with repeaters located most nearby but repeaters securing an optimum communication state respectively. This reason can be considered to be that any shielding object exists between the repeater R 2  and the terminal N 1  and between the repeater R 2  and the terminal N 3 .  
         [0049]    To select a repeater securing such an optimum communication state, it is permissible to collect information about reception condition (antenna power, bit error) of electronic wave between each repeater and each terminal at a single repeater which serves as a master repeater and then select a repeater securing an optimum communication state. Alternatively, it is also permissible for each terminal to send a reception condition detecting request to respective repeaters in succession and receive an echo signal about a communication state detected corresponding to the detection request in order to select a repeater securing an optimum communication state therewith.  
         [0050]    A hardware structure of each of the repeaters R 1 , R 2 , R 3  will be described with reference to FIG. 9.  
         [0051]    As shown in FIG. 9, each repeater comprises an antenna  21  for sending or receiving electronic wave, a transmitter  22  for transmitting electronic wave through this antenna  21 , a receiver  23  for receiving electronic wave through the antenna  21 , a controller  24  for controlling the transmitter  22  and receiver  23  and a clock generator  25  for generating clocks for these units.  
         [0052]    The transmitter  22  includes a transmission buffer  28  for holding transmission data of other repeaters sent from reception buffer  27  of the receiver  23  through a signal processing portion  26  of the controller  24  and transmission data sent from the transmitter, a modulating portion  29  for modulating the transmission data and a transmitting portion  30  for transmitting the transmission data modulated by the modulating portion  29 .  
         [0053]    The receiver  23  includes a receiving portion  31  for receiving transmission data, a demodulating portion  32  for demodulating the transmission data received by the receiving portion  31  and a reception buffer  27  for holding transmission data sent from the demodulating portion  32  and transmission data sent from the transmission buffer  28  of the transmitter  22  through the signal processing portion  26  of the controller  24 . Data received by the receiver  23  is also transmitted to an antenna power detecting portion  33  and a bit error detecting portion  34  and data held by the reception buffer  27  is sent to other receivers and the transmission buffer  28 .  
         [0054]    The controller  24  comprises a signal processing portion  26  for carrying out signal processing such as attachment of transmission data destination, sender&#39;s address and the like and a controlling portion  35  for controlling the signal processing portion  26 , transmitter  22  and receiver  23  and switching transmission and reception.  
         [0055]    The controlling portion  35  includes a CPU for carrying out various processings and a memory for storing an instruction for this processing. Instructions and timing restriction carried out by this control portion  35  are held by this memory and loaded onto the CPU as required for execution.  
         [0056]    Next, an installation example of a repeater in the radio LAN system of the second embodiment will be described.  
         [0057]    [0057]FIG. 10 is a perspective view showing a first installation example. As shown in FIG. 10, the repeater R 1  is placed on a dash board in front of the front seat so as to communicate with a terminal brought into the front seat.  
         [0058]    A repeater R 2  is mounted on the ceiling above the front seat to communicate with a terminal brought into the front seat and a terminal brought into a second seat. Likewise, a repeater R 3  is mounted on the ceiling above the second seat to communicate with a terminal brought into the second seat and a terminal brought into a third seat.  
         [0059]    A repeater R 4  is mounted on the ceiling in front of the third seat to communicate with a terminal brought into the third seat.  
         [0060]    Consequently, as shown in FIG. 11, a terminal installed in the front seat is capable of communicating with a repeater securing a better communication state of the repeater R 1  or R 2 . A terminal installed in the second seat is capable of communicating with a repeater securing a better communication state of the repeater R 2  or R 3 . A terminal installed in the third seat is capable of communicating with a repeater securing a better communication state of the repeater R 3  or R 4 .  
         [0061]    Next, FIG. 12 is a perspective view showing a second installation example. As shown in FIG. 12, the repeater R 1  is mounted on a front pillar in front of the front seat to communicate with a terminal brought into the front seat.  
         [0062]    The repeater R 2  is mounted on the drip line to the left above the front seat to communicate with a terminal brought into the front seat and a terminal brought into the second seat. Likewise, the repeater R 3  is mounted on the drip line to the left above the second seat to communicate with a terminal brought into the second seat and a terminal brought into the third seat.  
         [0063]    Further, the repeater R 4  is mounted on the drip line to the left in front of the third seat to communicate with a terminal brought into the third seat.  
         [0064]    As a result of the installation of the repeaters as shown in FIG. 12, a terminal installed in the front seat is capable of communication with a repeater securing a better communication state of the repeater R 1  or R 2  like the first embodiment. A terminal installed in the second seat is capable of communicating with a repeater securing a better communication state of the repeater R 2  or R 3 . A terminal installed in the third seat is capable of communicating with a repeater securing a better communication state of the repeater R 3  or R 4 .  
         [0065]    As a third installation example, the repeaters may be mounted on the front pillars and drip lines of both the left and right sides as shown in FIG. 13.  
         [0066]    As shown in FIG. 13, repeaters R 1   a,  R 1   b  are mounted on the front pillars in front of the front seat. Repeaters R 2   a,  R 2   b  are mounted on the drip lines in front of the second seat. Repeaters R 3   a,  R 3   b  are mounted on the drip lines in front of the third seat.  
         [0067]    According to the third installation example, as shown in FIG. 14, a terminal installed in the front seat is capable of communicating with a repeater securing a better communication state of the repeater R 1   a  or R 1   b.  A terminal installed in the second seat is capable of communicating with a repeater securing a better communication state of the repeater R 2   a  or R 2   b.  A terminal installed in the third seat is capable of communicating with a repeater securing a better communication state of the repeater R 3   a  or R 3   b.    
         [0068]    As shown in each installation example, plural repeaters are provided at a position allowing communication with a terminal installed in each seat row and a repeater securing a optimum communication state is selected from the plural repeaters to carry out communication by radio. Consequently, radio communication can be kept continuously even under such an environment in which no sufficient space can be secured and a terminal or shielding object may be moved as the vehicle compartment.  
         [0069]    Further, by mounting the repeater R 1  in front of the front seat, the repeater R 1  is capable of communicating with a navigation system, audio system or the like (not shown) mounted on console easily. By mounting the repeater R 3 , R 3   b  or R 4  on the third seat, the repeater R 3  is capable of communicating with a back camera (not shown) provided on a rear portion of a vehicle. Further, the repeater may be connected to a CD changer, DVD changer, digital TV monitor or the like (not shown) provided in trunk through wire so that it is capable of communicating therewith.  
         [0070]    In the above described installation examples, it is assumed that the repeaters R 1 , R 2 , R 3 , R 3   a,  R 3   b,  R 4  are mounted in such a manner that they are capable of communicating with each other securely irrespective of radio communication or wired communication. Further, the quantity of the repeaters is not limited to four or six, but may be increased as the quantity of seat rows is increased like in bus. Conversely, the quantity of the repeaters may be decreased if that of the seat rows is decreased.  
         [0071]    Further, although in the above described installation example, the repeater R 1  is mounted on the dash board or front pillar in front of the front seat, it is not restricted to these positions, but the repeater may be mounted on any place such as rearview mirror and console as long as it is capable of communicating by radio.  
         [0072]    Likewise, the repeaters R 2 , R 3 , R 3   a,  R 3   b,  R 4  maybe also mounted at any place respectively if each of them is capable of communicating by radio with a terminal installed in the second seat or third seat.  
         [0073]    Further, the installation examples shown in FIGS. 2, 5,  6 ,  10 ,  12  and  13  may be combined with each other.  
         [0074]    Although the second embodiment has been described about a case where the repeaters are mounted on a vehicle, this embodiment may be applied to conveyance having seats such as airplane and ship.  
         [0075]    As described above, according to the vehicle compartment radio LAN system of the first embodiment of the present invention, communication can be carried out between terminals installed in different seat rows.  
         [0076]    Further, the vehicle compartment radio LAN system of the second embodiment makes it possible to communicate continuously by radio even under such an environment in which no sufficient space can be secured and a terminal or shielding object is moved as vehicle compartment.  
         [0077]    It should be understood that many modifications and adaptations of the invention will become apparent to those skilled in the art and it is intended to encompass such obvious modifications and changes in the scope of the claims appended hereto.