Abstract:
The present invention relates to a communication system and method in a ship area network. In a network of a structure including a plurality of shielded regions, communication is performed between terminals provided in the shielded region by using wireless communication, and communication is performed between terminals provided in different shielded regions by further using power line communication, optical communication, or the power line communication and the optical communication in addition to the wireless communication. Therefore, it is possible to obtain advantages of minimizing inconvenience, which is caused by using only wire communication in the related art, and enlarging a working area.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a communication system and method in a ship area network, and more particularly, to a communication system and method between mobile terminals in a ship area network where electric waves are shielded. 
     This work was supported by the IT R&amp;D program of MIC/IITA [2005-S-022-03, Embedded Software-based SmarTown Solution]. 
     2. Description of the Related Art 
     The demand for a mobile communication terminal as personal portable communication means has increased in recent years, such that the mobile communication terminal becomes a necessity of life. Since it is not possible to satisfy the consumer&#39;s desire with a function of communication means for the transmission/reception of only voice, there has been released a mobile communication terminal having various and new functions and additional services. 
     However, wireless communication can not be performed between communication terminals by using a communication system in the related art in an environment such as a network in a ship area, which is generally surrounded by steel so that electric waves are shielded. Due to the above reason, only wire communication has been used. Therefore, there is a limitation on a working area where working is freely performed. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to solve the above-mentioned problem, and it is an object of the present invention to provide a communication system and method in a ship area network that performs communication between terminals in a region shielded by steel by using wireless communication, and performs communication between terminals in different shielded regions, which are shielded so that electric waves do not pass through the regions, by using power line communication and optical communication. 
     According to an aspect of the present invention, there is provided a communication system in a network of a structure including a plurality of shielded regions. The communication system includes a wireless communication device that is used to perform communication between terminals located in the shielded regions, and a power line communication device that is connected to the wireless communication device and provides power line communication. Communication is provided between terminals located in the same shielded region by using the wireless communication device, and communication is provided between terminals located in different shielded regions by using the wireless communication device and the power line communication device. 
     The communication system may further include an optical network device that is connected to the power line communication device and provides optical communication. Communication may be provided between the terminals located in the different shielded regions by further using the optical network device as well as the wireless communication device and the power line communication device, in consideration of a distance between the terminals and the region to which the terminal belongs. 
     The wireless communication device may include at least one wireless communication repeater. The wireless communication repeater directly routes and transmits a signal from a first terminal to a second terminal in consideration of the location of the second terminal, or converts the signal into an upstream signal and transmits the upstream signal to the power line communication device. 
     The power line communication device may include at least one power line communication repeater. The power line communication repeater receives a signal supplied from the wireless communication device and then transmits the signal to another power line communication repeater in consideration of the position of a second terminal, or converts the received signal into an upstream signal and transmits the upstream signal to the optical network device. 
     One power line communication repeater may be in charge of one shielded region. 
     The optical network device may include at least one optical communication repeater. The optical communication repeater receives a signal supplied from the power line communication repeater, and transmits the signal to another optical communication repeater that is in charge of a region to which the second terminal belongs. 
     When receiving a signal from the optical network device, the power line communication repeater may convert the received signal into a downstream signal and transmit the downstream signal to the wireless communication device. Further, when receiving a downstream signal from the power line communication device, the wireless communication repeater may transmit the received signal to the second terminal. 
     According to another aspect of the present invention, there is provided a communication system in a network of a structure including a plurality of shielded regions. The communication system performs communication between terminals provided in the shielded region by using wireless communication; and performs communication between terminals provided in different shielded regions by further using power line communication, optical communication, or the power line communication and the optical communication in addition to the wireless communication. 
     According to another aspect of the present invention, there is provided a communication method in a network of a structure including a plurality of shielded regions. The communication method includes performing communication between terminals located in the shielded region by using wireless communication; and performing communication between terminals located in different shielded regions by further using power line communication, or optical communication, or the power line communication and the optical communication in addition to the wireless communication. 
     According to the present invention, communication is performed between terminals in a region shielded by steel by using wireless communication, and communication is performed between terminals in different shielded regions, which are shielded so that electric waves do not pass through the regions, by using power line communication. Therefore, it is possible to obtain advantages of minimizing inconvenience, which is caused by using only wire communication in the related art, and enlarging a working area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing an embodiment of the internal structure of a ship to which the present invention is applied; 
         FIG. 2  is a block diagram of a communication system in a ship area network according to an embodiment of the present invention; 
         FIG. 3  is a view showing communication flow between two mobile terminals provided in a region, which is shielded by steel, of a ship area in accordance with an embodiment of the present invention; 
         FIG. 4  is a view showing communication flow between two mobile terminals provided in different shielded regions, which are adjacent to each other, of a ship area in accordance with an embodiment of the present invention; and 
         FIG. 5  is a view showing communication flow between two mobile terminals provided in different shielded regions, which are far from each other, of a ship area in accordance with an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be described below with reference to accompanying drawings. 
       FIG. 1  is a view showing an embodiment of the internal structure of a ship to which the present invention is applied. 
     Each of region A, region B, and region C shown in  FIG. 1  is surrounded by steel so that electric waves are shielded. Accordingly, wireless signals can be freely transmitted only within each region. 
     In a communication system according to the present invention, a wireless communication method is used between two terminals provided in region A, and a power line communication method as well as a wireless communication method is used between a terminal provided in region A and a terminal provided in region B. Further, an optical communication method is further used between a terminal provided in region A and a terminal provided in region C, so that intercommunication is performed between the terminals. 
       FIG. 2  is a block diagram of a communication system in a ship area network according to an embodiment of the present invention. 
     As shown in  FIG. 2 , the communication system according to the present invention generally includes an optical network device  100 , a power line communication device  200 , and a wireless communication device  300 . 
     The optical network device  100  includes at least one optical communication repeater  110 . Although not shown, an optical communication controller, an optical communication transceiver, and a power line communication transceiver are included in the optical communication repeater  110 . The optical communication transceiver performs transmission and reception for the communication with other optical communication repeaters of the optical network device  100 , and the power line communication transceiver performs transmission and reception for the communication with at least one power line communication repeater  210  connected to the optical communication repeater  110 . Further, the optical communication controller controls the flow of communication data transmitted to other optical communication repeaters through the optical communication repeater  110 , or the flow of the communication data transmitted to the power line communication repeater  210  through the optical communication repeater  110 . 
     The power line communication device  200  includes at least one power line communication repeater  210 . Although not shown, a power line communication controller, a power line communication transceiver, an optical communication transceiver, and a wireless communication transceiver are included in the power line communication repeater  210 . The power line communication transceiver transmits and receives communication data to/from other power line communication repeaters connected to the power line communication repeater, and the optical communication transceiver performs transmission and reception of data with the power line communication repeaters  210 . The wireless communication transceiver performs transmission and reception of data with wireless communication repeaters  310  of the wireless communication device  300  that is a subordinate device of the power line communication device  200 . Further, the power line communication controller is connected to the power line communication transceiver, the optical communication transceiver, and the wireless communication transceiver, and controls the data flow of a downstream signal or an upstream signal. 
     Furthermore, the wireless communication device  300  includes at least one wireless communication repeater  310  and at least one mobile terminal  311 . The wireless communication repeater  310  includes a wireless communication controller, a wireless communication transceiver, and a power line communication transceiver. The wireless communication transceiver performs transmission and reception of communication data with other wireless communication repeaters, and the power line communication transceiver performs transmission and reception of communication data with the power line communication repeaters  210  of the power line communication device  200  that is a superordinate device. Further, the wireless communication controller is connected to the wireless communication transceiver and the power line communication transceiver, and controls the flow of a downstream signal transmitted to the mobile terminal  311  or an upstream signal transmitted from the mobile terminal  311  to the superordinate device. 
     In the embodiment shown in  FIG. 2 , the power line communication repeaters  210  have been connected to other power line communication repeaters, which belong to regions assigned to the optical communication repeaters  110  of the superordinate device, in the form of a token ring. However, the embodiment of the present invention is not limited thereto, and the power line communication repeaters may have a mesh structure in which all of the power line communication repeaters, which are provided around one optical communication repeater  110  in a region assigned to the optical communication repeater, are connected to the optical communication repeater in the form of one-to-one connection. In this case, since the power line communication repeater  210  does not need to communicate with other power line communication repeaters, the power line communication transceiver is not needed. 
     When communicating with one another using the communication system in the ship area shown in  FIG. 2 , the mobile terminals may communicate with one another by methods shown in  FIGS. 3 to 5  according to conditions. The methods will be sequentially described below. 
       FIG. 3  is a view showing communication flow between two mobile terminals provided in a region, which is shielded by steel, of a ship area in accordance with an embodiment of the present invention. 
       FIG. 3  shows the flow of a signal that is transmitted from a first mobile terminal  311 - 1  to a third mobile terminal  311 - 3 . The signal sent from the first mobile terminal  311 - 1  is transmitted to a first wireless communication repeater  310 - 1  that is in charge of the first mobile terminal  311 - 1  (S 301 ). The first wireless communication repeater  310 - 1  recognizes that the third mobile terminal  311 - 3  serving as the destination is not a mobile terminal assigned to its own but a mobile terminal assigned to a second wireless communication repeater  310 - 2 . Then, the first wireless communication repeater transmits a signal to the second wireless communication repeater  310 - 2  (S 302 ). The second wireless communication repeater  310 - 2 , which receives the signal, transmits a signal to the third mobile terminal  311 - 3  assigned to its own. The transmission of a signal from the third mobile terminal  311 - 3  to the first mobile terminal is performed in reverse order of the above process. 
     In the embodiment of  FIG. 3 , mobile terminals controlled by different wireless communication repeaters communicate with each other. However, the first and second mobile terminals  311 - 1  and  311 - 2  controlled by the same wireless communication repeater can communicate with each other through the only first wireless communication repeater  310 - 1 . This is applied to the communication between two mobile terminals that are close to each other, as shown in  FIG. 3 . 
       FIG. 4  is a view showing communication flow between two mobile terminals provided in different shielded regions, which are adjacent to each other, of a ship area in accordance with an embodiment of the present invention. 
       FIG. 4  shows the flow of a signal that is transmitted from a first mobile terminal  311 - 1  to a fourth mobile terminal  311 - 4 . The first and fourth mobile terminals (for example, the terminal provided in region A of  FIG. 1  and the terminal provided in region B) are provided in different regions. The regions are shielded so that electric waves do not pass through the regions. 
     The signal sent from the first mobile terminal  311 - 1  is transmitted to a first wireless communication repeater  310 - 1  that is in charge of the first mobile terminal  311 - 1  (S 401 ). The first wireless communication repeater  310 - 1 , which receives the signal, coverts the received signal into an upstream signal, and transmits the upstream signal to a first power line communication repeater  210 - 1  that is a superordinate device (S 402 ). The first power line communication repeater  210 - 1 , which receives the signal, transmits the signal to a second power line communication repeater  210 - 2  that is in charge of the fourth mobile terminal  311 - 4  (S 403 ). The second power line communication repeater  210 - 2  converts the received signal into a downstream signal, and transmits the downstream signal to a third wireless repeater  310 - 3  connected to the fourth mobile terminal  311 - 4  (S 404 ). Finally, the third wireless repeater  310 - 3 , which receives the signal, converts the signal into a wireless signal, and transmits the wireless signal to the fourth mobile terminal  311 - 4  (S 405 ). As a result, the signal is transmitted to the fourth mobile terminal that is the destination. 
     The transmission of a signal from the fourth mobile terminal  311 - 4  to the first mobile terminal  311 - 1  is performed in reverse order of the above process. 
       FIG. 5  is a view showing communication flow between two mobile terminals provided in different shielded regions, which are far from each other, of a ship area in accordance with an embodiment of the present invention. 
     A distance between two mobile terminals  311 - 1  and  311 - 5  (for example, the terminal provided in region A of  FIG. 1  and the terminal provided in region C) is larger in the embodiment of  FIG. 5  as compared to the embodiment of  FIG. 4 . 
     The signal sent from the first mobile terminal  311 - 1  is transmitted to the first wireless communication repeater  310 - 1  that is in charge of the first mobile terminal  311 - 1  (S 501 ). The first wireless communication repeater  310 - 1 , which receives the signal, coverts the received signal into an upstream signal, and transmits the upstream signal to the first power line communication repeater  210 - 1  that is a superordinate device (S 502 ). The first power line communication repeater  210 - 1 , which receives the signal, again converts the received signal into an upstream signal, and transmits the upstream signal to a first optical communication repeater  110  ( 503 ). The first optical communication repeater  110 , which receives the signal, recognizes that a second optical communication repeater  110 - 2  is in charge of a fifth mobile terminal  311 - 5  serving as the destination, and transmits the signal to the second optical communication repeater  110 - 2  (S 504 ). The second optical communication repeater  110 - 2  converts the received signal into a downstream signal, and transmits the downstream signal to the fourth power line communication repeater  210 - 4  (S 505 ). The fourth power line communication repeater  210 - 4  again converts the received signal into a downstream signal, and transmits the downstream signal to a fourth wireless communication repeater  310 - 4  (S 506 ). Finally, the fourth wireless communication repeater  310 - 4  converts the received signal into a wireless signal, and transmits the wireless signal to the fifth mobile terminal  311 - 5  that is the destination (S 507 ). 
     The transmission of a signal from the fifth mobile terminal  311 - 5  to the first mobile terminal  311 - 1  is performed in reverse order of the above process. 
     Although the preferred embodiments of the present invention have been disclosed, those skilled in the art will appreciate that various modifications and changes without departing from the scope and spirit of the invention. For example, as for all of the embodiments, a ship has been described as an example of a place that includes shielded inner spaces. However, the present invention is not limited to the communication in the ship, and may be applied to a factory where various shielded spaces are provided. Therefore, as long as a plurality of spaces is provided, the present invention may be any place.