Patent Publication Number: US-2023163832-A1

Title: Relief ship

Description:
TECHNICAL FIELD 
     The present disclosure relates to a relief ship dispatched to a coastal disaster site or the like. 
     BACKGROUND ART 
     A conventionally-proposed approach to a communication failure in a wireless communication network is to dispatch a mobile relay station for relaying communication between a base station and a wireless terminal to the area where the failure has occurred and thereby improve the communication situation. Patent Literatures 1 and 2 disclose such kinds of technologies. 
     In the wireless communication system of Patent Literature 1, radio waves sent from a push server connected to a wireless communication network are transmitted to a wireless terminal through a communication satellite and a wireless communicator mounted on an aircraft (or a ship). The push server sends the flight schedule of the aircraft (in particular, information related to the time period during which the wireless terminal can perform communication) to the wireless terminal since the communication-enabled area created by the wireless communicator moves in accordance with the flight schedule of the aircraft 
     In the communication system of Patent Literature 2, an airborne communication relay such as HAPS is connected to a core network of a mobile communication network via a feeder station that is a relay station located on the ground or at sea. The airborne communication relay is located in a given altitude range and creates a three-dimensional wireless communication area in a cell creation target region defined at a given altitude. 
     There are ships (hospital ships) configured to serve the function of hospitals to deliver medical care to sick or insured people at sites affected by famines or serious disasters. The hospital ships are known to include not only common pieces of ship equipment but also medical installations such as patient bedrooms, examination rooms, treatment rooms, surgery rooms, and ICUs and to be furnished with a variety of medical devices such as testing devices, surgical devices, X-ray devices, and computerized tomography scanning devices. Some recently-developed hospital ships are configured to allow doctors to make remote examinations or perform remote surgery using remotely-controlled surgical robots. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Laid-Open Patent Application Publication No. 2017-169115 
     PTL 2: Japanese Laid-Open Patent Application Publication No. 2019-47467 
     SUMMARY OF INVENTION 
     Technical Problem 
     At a disaster site, it is envisaged that a good communication situation cannot be achieved because of, for example, damage to the communication infrastructure. There is also a possibility that the capacity of the communication infrastructure is insufficient to meet momentarily and rapidly increased communication demand. 
     The present disclosure addresses the above circumstances, and an object of the present disclosure is to propose a relief ship (e.g., a hospital ship) dispatched to a coastal disaster site or the like, the relief ship being adapted to improve the communication situation at the disaster site or the like. 
     Solution to Problem 
     A relief ship according to one aspect of the present disclosure includes: 
     a hull; 
     an on-board relay station mounted on the hull to create a first wireless communication area on and/or around the hull; 
     at least one mover mounted on the hull and movable to a place away from the hull; and 
     a mobile relay station mounted on the mover, wherein 
     the on-board relay station is configured to receive a radio wave transmitted from a ground base station and transmit the radio wave to a wireless terminal located in the first wireless communication area and configured to receive a radio wave transmitted from the wireless terminal located in the first wireless communication area and transmit the radio wave to the ground base station, and 
     the mobile relay station is configured to relay radio waves between the on-board relay station and the ground base station. 
     The relief ship with the above configuration is anchored off the coast of a disaster site where a wireless communication installation has been damaged, and the mover, for which the relief ship is a base, is moved to a land, sky, or sea area located between the ground base station and the on-board relay station. Thus, the ground base station located away from the disaster site and the on-board relay station can exchange radio waves with each other via the mobile relay station. This makes it possible to deliver stable radio waves to the wireless terminal located in the first wireless communication area and improve the communication situation in the first wireless communication area. 
     A relief ship according to another aspect of the present disclosure includes: 
     a hull; 
     an on-board relay station mounted on the hull; 
     at least one mover mounted on the hull and movable to a place away from the hull; and 
     a mobile relay station mounted on the mover, wherein 
     the at least one mover includes a first mover on which a first mobile relay station is mounted, 
     the first mobile relay station is configured to create a second wireless communication area around the first mover, configured to receive a radio wave transmitted from a ground base station and transmit the radio wave to a wireless terminal located in the second wireless communication area, and configured to receive a radio wave transmitted from the wireless terminal located in the second wireless communication area and transmit the radio wave to the ground base station, and 
     the on-board relay station is configured to relay radio waves between the ground base station and the first mobile relay station. 
     The relief ship with the above configuration is anchored off the coast of a disaster site where a wireless communication installation has been damaged, and the first mover, for which the relief ship is a base, is moved to the disaster site. Thus, the ground base station located away from the disaster site and the first mobile relay station can exchange radio waves with each other via the on-board relay station. This makes it possible to deliver stable radio waves to the wireless terminal located in the second wireless communication area and improve the communication situation in the second wireless communication area. 
     Advantageous Effects of Invention 
     The present disclosure can propose a relief ship (e.g., a hospital ship) dispatched to a coastal disaster site or the like, the relief ship being adapted to improve the communication situation at the disaster site or the like. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a side view showing an overall configuration of a relief ship according to an exemplary embodiment of the present disclosure. 
         FIG.  2    illustrates a first communication support system built for the relief ship. 
         FIG.  3    shows the relief ship dispatched to a disaster site. 
         FIG.  4    illustrates a second communication support system built for the relief ship. 
         FIG.  5    illustrates a variant of the second communication support system built for the relief ship. 
         FIG.  6    shows the relief ship dispatched to a disaster site. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG.  1    is a side view showing an overall configuration of a relief ship  1  according to an exemplary embodiment of the present disclosure. The following description assumes that the present disclosure is applied to a hospital ship which is one aspect of the relief ship  1 . The relief ship  1  is not limited to the hospital ship and may be a ship used for relief activities other than medical activities, such as transfer of relief supplies. 
     Like a common ship, the relief ship  1  of  FIG.  1    includes a hull  11 , a propeller  12 , a main engine  13 , an electricity generator  14 , and a storage battery  15 . The main engine  13  generates drive power for the propeller  12 . The main engine  13  may be a diesel engine, a turbine engine, an electric propulsion engine, or a combination of these engines. The electricity generator  14  generates electricity using drive power received from an engine for electricity generation (not shown), and supplies the generated electricity to the inboard electrical system and the storage battery  15 . The main engine  13  may function also as the engine for electricity generation. 
     Like a common ship, the relief ship  1  includes various nautical instruments. The nautical instruments include, for example, a chronometer, a gyrocompass, a ship speed indicator, a wind direction/speed indicator, a bathometer, a radar, and a GPS receiver. The GPS receiver receives a signal from a GPS satellite (not shown) flying over the ship and determines the current position of the relief ship  1 . 
     A bridge  16  is located at the top of the relief ship  1 . Inside the bridge  16  there is a control cabin, which includes pieces of equipment for maneuvering of the relief ship  1 . A flight deck  17  is located at the top of the relief ship  1 . 
     The relief ship  1  is equipped with at least one helicopter  51 , wheeled vehicle  52 , or small boat  53 . The helicopters  51  and the wheeled vehicles  52  are located on the flight deck  17 . The small boats  53  are located on a lateral side of the hull  11 . The helicopters  51 , wheeled vehicles  52 , and small boats  53  are used primarily for transfer of goods and personnel from the relief ship  1  to a disaster site (or vice versa). The helicopters  51 , wheeled vehicles  52 , and small boats  53  may include devices for emergency medical care or emergency transfer to contribute to rescue or relief activities. At least one of the helicopters  51  may be an emergency medical helicopter. 
     The relief ship  1  according to the present embodiment is a hospital ship and includes installations that enable the relief ship  1  to serve the function of a hospital. The relief ship  1  includes medical installations  18  such as a patient bedroom, an examination room, and a surgery room. The examination room is equipped with a remote examination device to allow a doctor on the ground to make a remote examination. The remote examination device includes, for example, a patient interface and a communicator. The patient interface can be constructed of a display, a microphone, a speaker, and any other suitable component. The surgery room is equipped with a patient-side system of a surgical robot system to allow a doctor on the ground to perform remote surgery. The patient-side system can be constructed, for example, of a remotely-controlled robot arm, a robot controller, a monitor, and a communicator. 
     The installations of the relief ship  1  are not limited to those described above. The relief ship  1  desirably includes accommodations, storage installations for foodstuffs and other goods, and lifeline installations such as that for electricity generation, in addition to the medical installations  18 . This makes it possible to supply water and electricity and continue relief activities for a relatively long period of time independently of the situation of the disaster site or other factors. It is desirable for the relief ship  1  to further include a storage installation for storage of relief supplies. This makes it possible to deliver the relief supplies from the relief ship  1  to a disaster site or any other destination using movers M (helicopters  51 , wheeled vehicles  52 , and small boats  53 ) mounted on the relief ship  1 . 
     The relief ship  1  configured as described above includes a communication support system that supports establishment of a temporary wireless communication network. The communication support system is at least one of first and second communication support systems  100 A and  100 B which will be described hereinafter. 
     [First Communication Support System  100 A] 
     The first communication support system  100 A will be described first. As shown in  FIG.  2   , the first communication support system  100 A includes an on-board relay station  40  mounted on the hull  11  of the relief ship  1 , at least one mover M mounted on the hull  11 , and a mobile relay station  70  mounted on the mover M. The mover M may be any one of the helicopters  51 , wheeled vehicles  52 , and small boats  53 . 
     The on-board relay station  40  includes an antenna  41 , a relay  42 , and an electricity feeder  43 . The relay  42  includes a receiving amplifier, a transmitting amplifier, a modulator/demodulator, a switcher, a GPS receiver, and a network controller. The on-board relay station  40  receives radio waves emitted by a ground base station  60  and emits the radio waves to wireless terminals  50  located on and/or around the ship. The on-board relay station  40  receives radio waves emitted by the wireless terminals  50  located on and/or around the ship and retransmits (forwards) the radio waves to the ground base station  60 . The radio waves emitted or retransmitted from the on-board relay station  40  may be amplified, modulated, or demodulated to higher levels or outputs. A first wireless communication area A 1  (cell) where wireless communication is enabled is created on and/or around the hull  11  by the on-board relay station  40 . 
     The on-board relay station  40  is connected to a wired communication network  19  located in the relief ship  1 . The on-board relay station  40  can perform radio wave/signal conversion and exchange signals with inboard wired terminals  55  connected to the wired communication network  19 . The inboard wired terminals  55  may include, for example, the above-mentioned remote examination device, the above-mentioned surgical robot system (patient-side system), and information instruments located in the ship. 
     The mobile relay station  70  includes an antenna  71 , a relay  72 , and an electricity feeder  73 . The relay  72  includes a receiving amplifier, a transmitting amplifier, a modulator/demodulator, and a controller. The mobile relay station  70  relays radio waves between the on-board relay station  40  and the ground base station  60 . That is, the mobile relay station  70  receives radio waves from the ground base station  60  and retransmits the radio waves to the on-board relay station  40 , and receives radio waves from the on-board relay station  40  and retransmits the radio waves to the ground base station  60 . The radio waves retransmitted from the mobile relay station  70  may be amplified to higher levels or outputs. 
     The relief ship  1  described above includes: a hull  11 ; an on-board relay station  40  mounted on the hull  11  to create a first wireless communication area A 1  on and/or around the hull  11 ; at least one mover M mounted on the hull  11  and movable to a place away from the hull  11 ; and a mobile relay station  70  mounted on the mover M. The on-board relay station  40  is configured to receive a radio wave transmitted from a ground base station  60  and transmit the radio wave to a wireless terminal  50  located in the first wireless communication area A 1  and configured to receive a radio wave transmitted from the wireless terminal  50  located in the first wireless communication area A 1  and transmit the radio wave to the ground base station  60 . The mobile relay station  70  is configured to relay radio waves between the on-board relay station  40  and the ground base station  60 . 
     The relief ship  1  including the first communication support system  100 A configured as described above is dispatched to, for example, a coastal region affected by a tsunami or an earthquake. In the event that overland routes to a disaster site are blocked due to the natural disaster or any other reason, it is effective to approach the disaster site from the sea by means of a ship in order to quickly take emergency disaster countermeasures such as rescue of injured people. In the example shown in  FIG.  3   , the relief ship  1  is at anchor off the coast of the disaster site D. At the disaster site D, the local communication infrastructure has been damaged, and the wireless communication function has been impaired. To address this situation, the mover M, for which the relief ship  1  is a base, is moved to a land, sky, or sea area located between a well-functioning ground base station  60  in the vicinity of the disaster site D and the on-board relay station  40  of the relief ship  1 . In the example shown in  FIG.  3   , the mover M is the helicopter  51 . The mover M is not limited to the helicopter  51  and may be the wheeled vehicle  52  or small boat  53  for which the relief ship  1  is a base. There may be two or more mobile relay stations  70  that perform a relay function between the ground base station  60  and the on-board relay station  40 . In this case, radio waves are exchanged between the mobile relay stations  70 . 
     The ground base station  60  located away from the disaster site D and the on-board relay station  40  can exchange radio waves with each other through the mobile relay station  70 . This makes it possible to deliver stable radio waves to the wireless terminal  50  located in the first wireless communication area A 1  and improve the communication situation in the first wireless communication area A 1 . 
     The on-board relay station  40  described above may be connected to a wired communication network  19  located in the hull  11  and configured to exchange signals with a wired terminal  55  connected to the wired communication network  19 . When being at anchor off the coast of the disaster site D with a damaged communication infrastructure, the relief ship  1  can receive stable radio waves from the ground base station  60  at a high speed, in a large volume, and with a small delay. Such a configuration is beneficial especially to hospital ships adapted for remote examinations and remote surgery like the relief ship  1  according to the present embodiment. 
     [Second Communication Support System  100 B] 
     Next, the second communication support system  100 B will be described. As shown in  FIGS.  4  and  5   , the second communication support system  100 B includes an on-board relay station  140  mounted on the hull  11  of the relief ship  1 , at least one mover M 1 , M 2 , or M 3  mounted on the hull  11 , and a mobile relay station  170 A,  170 B, or  170 C mounted on the mover M 1 , M 2 , or M 3 . The mover M 1 , M 2 , or M 3  may be any one of the helicopters  51 , wheeled vehicles  52 , and small boats  53 . 
     As shown in  FIG.  4   , the at least one mover M 1 , M 2 , or M 3  includes a first mover M 1  on which a first mobile relay station  170 A is mounted. The first mobile relay station  170 A includes an antenna  171 , a relay  172 , and an electricity feeder  173 . The relay  172  includes a receiving amplifier, a transmitting amplifier, a modulator/demodulator, a switcher, a GPS receiver, and a controller. The first mobile relay station  170 A receives radio waves emitted by the ground base station  60  and emits the radio waves to the wireless terminals  50  located around the first mover M 1 . The first mobile relay station  170 A receives radio waves emitted by the wireless terminals  50  located around the first mover M 1  and retransmits the radio waves to the ground base station  60 . The radio waves emitted or retransmitted from the first mobile relay station  170 A may be amplified, modulated, or demodulated to higher levels or outputs. A second wireless communication area A 2  (cell) where wireless communication is enabled is created around the first mover M 1  by the first mobile relay station  170 A. 
     The on-board relay station  140  includes an antenna  141 , a relay  142 , and an electricity feeder  143 . The relay  142  includes a receiving amplifier, a transmitting amplifier, a modulator/demodulator, and a network controller. The on-board relay station  140  relays radio waves between the first mobile relay station  170 A and the ground base station  60 . That is, the on-board relay station  140  receives radio waves from the ground base station  60  and retransmits the radio waves to the first mobile relay station  170 A, and receives radio waves from the first mobile relay station  170 A and retransmits the radio waves to the ground base station  60 . The radio waves retransmitted from the on-board relay station  140  may be amplified to higher levels or outputs. As in the first communication support system  100 A, the on-board relay station  140  may be connected to the wired communication network  19 . 
     As shown in  FIG.  5   , the at least one mover M 1 , M 2 , or M 3  may include a second mover M 2  on which a second mobile relay station  170 B is mounted. The second mobile relay station  170 B relays radio waves between the on-board relay station  140  and the first mobile relay station  170 A. That is, the second mobile relay station  170 B receives radio waves from the on-board relay station  140  and retransmits the radio waves to the first mobile relay station  170 A, and receives radio waves from the first mobile relay station  170 A and retransmits the radio waves to the on-board relay station  140 . The second mobile relay station  170 B may have substantially the same configuration as the mobile relay station  70  of the first communication support system  100 A. 
     The at least one mover M 1 , M 2 , or M 3  may include a third mover M 3  on which a third mobile relay station  170 C is mounted. The third mobile relay station  170 C relays radio waves between the ground base station  60  and the on-board relay station  140 . That is, the third mobile relay station  170 C receives radio waves from the ground base station  60  and retransmits the radio waves to the on-board relay station  140 , and receives radio waves from the on-board relay station  140  and retransmits the radio waves to the ground base station  60 . The third mobile relay station  170 C may have substantially the same configuration as the mobile relay station  70  of the first communication support system  100 A. 
     The second communication support system  100 B may include both or either of the second and third movers M 2  and M 3 . 
     The relief ship  1  described above includes: a hull  11 ; an on-board relay station  140  mounted on the hull  11 ; at least one mover M 1 , M 2 , or M 3  mounted on the hull  11  and movable to a place away from the hull  11 ; and a mobile relay station  170 A,  170 B, or  170 C mounted on the mover M 1 , M 2 , or M 3 . The at least one mover M 1 , M 2 , or M 3  includes a first mover M 1  on which a first mobile relay station  170 A is mounted, and the first mobile relay station  170 A is configured to create a second wireless communication area A 2  around the first mover M 1 , configured to receive a radio wave transmitted from a ground base station  60  and transmit the radio wave to a wireless terminal  50  located in the second wireless communication area A 2 , and configured to receive a radio wave transmitted from the wireless terminal  50  located in the second wireless communication area A 2  and transmit the radio wave to the ground base station  60 . The on-board relay station  140  is configured to relay radio waves between the ground base station  60  and the first mobile relay station  170 A. 
     The relief ship  1  including the second communication support system  100 B configured as described above is dispatched to, for example, a coastal region affected by a tsunami or an earthquake. In the example shown in  FIG.  6   , the relief ship  1  is at anchor off the coast of the disaster site D. At the disaster site D, the local communication infrastructure has been damaged, and the wireless communication function has been impaired. To address this situation, the first mover M 1  is moved to the disaster site D. The first mover M 1  is, for example, an off-road wheeled vehicle  52  capable of traveling on rough roads in the disaster site D. The relief ship  1  includes a transporter T that transports the first mover M 1  from the ship to a location on the disaster site D (ground). In the example shown in  FIG.  6   , the helicopter  51  or small boat  53 , for which the relief ship  1  is a base, serves as the transporter T. 
     In the above configuration, the ground base station  60  located away from the disaster site and the first mobile relay station  170 A can exchange radio waves with each other through the on-board relay station  140 . This makes it possible to deliver stable radio waves to the wireless terminal  50  located in the second wireless communication area A 2  and improve the communication situation in the second wireless communication area A 2 . 
     Both the on-board relay station  140  and the first mobile relay station  170 A are mobile. However, during exchange of radio waves, the on-board relay station  140  and the first mobile relay station  170 A are at rest, and their positions can be determined. The position information can be used for purposes such as adjustment of the antennas in placement of the relay stations  140  and  170 A. 
     In the relief ship  1  configured as described above, the second mover M 2  may be moved from the relief ship  1  to a location between the relief ship  1  and the first mover M 1 , and the second mobile relay station  170 B mounted on the second mover M 2  may be used to relay radio waves between the on-board relay station  140  and the first mobile relay station  170 A. 
     The relaying of radio waves between the on-board relay station  140  and the first mobile relay station  170 A makes it possible, when there is an obstacle between the relief ship  1  and the first mover M 1 , to deliver the radio waves from the on-board relay station  140  to the first mobile relay station  170 A (or vice versa) while avoiding the obstacle. 
     Likewise, in the relief ship  1  configured as described above, the third mover M 3  may be moved from the relief ship  1  to a location between the relief ship  1  and the ground base station  60 , and the third mobile relay station  170 C mounted on the third mover M 3  may be used to relay radio waves between the ground base station  60  and the on-board relay station  140 . 
     The relaying of radio waves between the ground base station  60  and the on-board relay station  140  makes it possible, when there is an obstacle between the ground base station  60  and the relief ship  1 , to deliver the radio waves from the ground base station  60  to the on-board relay station  140  (or vice versa) while avoiding the obstacle. 
     In the example shown in  FIG.  6   , the second and third movers M 2  and M 3  are the helicopters  51 . However, each of the second and third movers M 2  and M 3  may be any one of the helicopters  51 , wheeled vehicles  52 , and small boats  53  for which the relief ship  1  is a base. There may be two or more second movers M 2  or two or more third movers M 3 . In this case, radio waves are exchanged between the mobile relay stations  170 B or between the mobile relay stations  170 C. 
     Although the foregoing has described a preferred embodiment of the present disclosure, the scope of the present disclosure embraces modifications made to the details of the structure and/or function of the above embodiment without departing from the gist of the present disclosure. For example, the configurations described above can be modified as follows. 
     For example, the relief ship  1  may further include a satellite communication base station. The satellite communication base station includes a satellite antenna, a service antenna, a transceiver, a supervisory controller, and an electricity feeder (all of which are not shown). The satellite communication base station uses the satellite antenna to exchange radio waves, through the mediation of a communication satellite, with an earth base station connected to a communication network  21 . The satellite communication base station uses the service antenna to exchange radio waves with the wireless terminal  50  located in or around the relief ship  1 . The satellite communication base station may be further configured to transmit radio waves to the mobile relay station  70  mounted on the mover M moved from the relief ship  1  or the mobile relay station  170 A mounted on the first mover M 1 . 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 : relief ship 
               11 : hull 
               19 : wired communication network 
               21 : communication network 
               40 ,  140 : on-board relay station 
               50 : wireless terminal 
               51 : helicopter 
               52 : wheeled vehicle 
               53 : small boat 
               55 : wired terminal 
               60 : ground base station 
               70 : mobile relay station 
               100 A: first communication support system 
               100 B: second communication support system 
               170 A to  170 C: mobile relay station 
             A 1 : first wireless communication area 
             A 2 : second wireless communication area 
             M, M 1  to M 3 : mover 
             T: transporter