JP2008311815A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that all radio terminals within a certain service area can not receive a content distribution service any more in the case that one AP (wireless access point) within the service area fails in a radio communication system in which one AP arranged in a service area and a plurality of radio terminals within the service area perform time division of the frequency band of one allocated channel to perform communication. <P>SOLUTION: The radio communication system maintains the distribution service and reduces interference by using: a means for changing the radiation directivities of a second AP having a service area adjacent to the service area of the failed first AP to make the second AP cover the service area of the first AP; a means for switching the radio communication service of the second AP from unicast to multicast; and a means for making a receiving directivity in a receiver within the service area of the first AP coincide with that of the second AP. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio communication system characterized by having a plurality of radio base stations and covering a radio base station in which another radio base station fails when some of the radio base stations fail.

  In recent years, wireless communication systems such as IEEE802.11a / b / g are becoming widespread. These are called a wireless local area network system or a wireless LAN system for short. These are communication systems in which the equivalent of Ethernet (registered trademark) used in a wired LAN system is replaced with radio.

  The wireless LAN system was initially assumed to be used in portable, portable personal computers, portable wireless terminals, and the like. Thereafter, use in various fields has been widened, and for example, a technique for applying a wireless LAN system to a terminal device whose use position is fixed has been proposed for the purpose of eliminating the complexity of wiring cables and the like.

  As an example of such a technique, a technique that uses a wireless LAN system for content distribution services such as video and audio in an aircraft has been proposed (see, for example, Patent Document 1). That is, in a plane, a wireless LAN system is arranged as a wireless communication system, and content data is transmitted to a wireless terminal installed in each passenger seat. In this way, a content distribution system using a wireless LAN system is formed, and complicated wiring cables and the like are reduced.

  As a configuration of such a content distribution system, first, content data corresponding to content to be provided to passengers is stored in a server control unit of the system. Further, a plurality of wireless access points (hereinafter referred to as “AP”), which are wireless base station devices connected to the server control unit, are installed in the aircraft. A wireless terminal is installed for each seat, and the position of each AP is set so that one AP covers a plurality of wireless terminals. At this time, first, the in-flight space is divided into a plurality of service areas, and each AP is assigned to the in-flight so that one AP corresponds to one service area. In addition, the directional antenna of the AP is arranged so as to radiate radio waves as much as possible without causing interference and disturbance to other service areas, and a channel that is fixed for each wireless terminal in the service area is used. Set up for wireless communication. Also, one AP and each wireless terminal in the service area are configured to communicate by dividing the frequency band of the channel in time. In this way, individual content distribution services can be implemented for a plurality of wireless terminals on one channel.

Further, a technique for switching to another radio base station when a radio base station of a mobile phone breaks down is disclosed (for example, see Patent Document 2).
JP 2006-33676 A JP 2000-78637 A

  However, in an aircraft, one AP arranged in a service area as in the conventional example and a plurality of wireless terminals in the service area communicate with each other by time-sharing the frequency band of one allocated channel. In a wireless communication system, when an AP in a certain service area fails, all wireless terminals in the service area cannot receive the content distribution service.

  The present invention has been made to solve the above-described problem. When detecting the presence or absence of an AP failure, the antenna directivity characteristics change and service change for an AP adjacent to the service area of the failed AP. Provided is a radio communication system capable of providing a service even in a service area where a conventional service could not be provided by performing (change from a unicast service to a multicast service).

To achieve the above object, a wireless communication system of the present invention includes a plurality of wireless base stations,
A wireless terminal that receives a service from a wireless base station;
A distribution server connected to the wireless base station by wire;
Means for detecting a failure of the radio base station;
Failure status storage means for storing the failure status of the radio base station;
Directivity changing means for changing the radiation directivity of the radio base station radio waves;
Service changing means for changing the communication service of the radio base station from unicast to multicast.

  By doing in this way, it becomes possible to perform the service of the service area which was serviced by the failed radio base station.

  Furthermore, the directivity changing means expands the radiation directivity of the radio base station adjacent to the failed radio base station to the service area of the failed radio base station, and the service change means extends to the adjacent radio base station whose service area is expanded. The station service may be changed from unicast to multicast.

  Furthermore, it may be characterized by having means for changing the radio wave radiation directivity of the wireless terminal in response to the radio wave radiation directivity of the radio base station.

  By doing so, it is possible to prevent unwanted radio wave interference from a failed radio base station.

  In addition, when there are a plurality of radio base stations that can cover a failed radio base station, a radio base station that has few radio terminals in service among the radio base stations that can be covered is preferentially selected. Also good.

  By doing so, it is possible to select a combination that suppresses the number of users who receive service degradation in selecting a combination of wireless base stations that cover a failed wireless base station.

  In addition, when there are a plurality of radio base stations that can cover a failed radio base station, a radio base station that has few radio terminals scheduled to be serviced is preferentially selected from the radio base stations that can be covered. Also good.

  By doing so, it is possible to select a combination that suppresses the number of users who receive service degradation in selecting a combination of wireless base stations that cover a failed wireless base station.

  In addition, when there are a plurality of radio base stations that can cover a faulty radio base station, the radio base stations that can be serviced are preferentially selected from among the radio base stations that can be covered. Also good.

  By doing so, it is possible to select a combination that suppresses the number of users who receive service degradation in selecting a combination of wireless base stations that cover a failed wireless base station.

  In addition, when there are a plurality of radio base stations that can cover the failed radio base station, the radio base station selected by the crew may be selected from the radio base stations that can be covered.

  By doing in this way, it becomes possible to select a combination that suppresses a decrease in service in selecting a combination of wireless base stations that cover a failed wireless base station.

  Further, when two radio base stations fail, and there is a radio base station that can cover both of the two failed radio base stations, one of the radio base stations is covered. The broadcasting directionality of the station may be expanded to the service area of two radio base stations that have failed, and the service may be changed to multicast.

  By doing so, it is possible to suppress an increase in the number of service areas in which the service is multicast.

  Further, a unicast service may be provided for some wireless terminals in the service area whose service is changed to multicast.

  By doing so, it is possible to suppress a decrease in service.

  Also, when there are multiple wireless base station combinations that cover the failed wireless base station, obtain an evaluation value for evaluating each wireless base station combination, and select the wireless base station combination that maximizes or minimizes the evaluation value It may be characterized by.

  By doing in this way, it becomes possible to select a combination that suppresses a decrease in service in selecting a combination of wireless base stations that cover a failed wireless base station.

  In addition, when there are a plurality of radio base stations that can cover the failed radio base station, the radio base station may be selected according to a predetermined priority order among the radio base stations that can be covered.

  By doing in this way, it becomes possible to select a combination that suppresses a decrease in service in selecting a combination of wireless base stations that cover a failed wireless base station.

  According to the radio communication system of the present invention, the directivity of the neighboring AP that covers the failed AP is changed, and the service to the service area of the failed AP is also performed by changing from the unicast service to the multicast service. It becomes possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 1 is an explanatory diagram of an aircraft fuselage part of the wireless communication system according to the first embodiment of the present invention.

  The wireless communication system includes a server control unit 10 having a function of controlling content data and devices, and content data and control commands transmitted from the server control unit 10 connected to the server control unit 10 via Ethernet (registered trademark). Are provided in the service area.

  The APs 11, 12, 13, and 14 provide a stable service by giving the antenna directivity and limiting the wireless area, thereby avoiding mutual radio interference.

  In addition, a plurality of passenger seats 15-1 to 15-N are arranged in a service area where each AP provides a service, and the passenger seats 15-1 to 15-N are wireless terminals 16-1 to 16-1. 16-N. The wireless terminal has a function of receiving and displaying data transmitted from the server control unit 10 via the APs 11, 12, 13, and 14 from the antenna.

  A specific data flow will be described with reference to FIG.

  In the service area 2 where the service is provided by the AP 12, passenger seats 15-4 to 15-6 in rows 4, 5, and 6 are arranged, and the AP 12 has the three rows as a normal cover range.

  For example, when a passenger on the passenger seat 15-5 in the row 5 operates the wireless terminal 16-5 on the back of the row 4 to use a content service such as a movie, the wireless terminal 16 in the row 4 -5 issues a command for requesting content data to the server control unit 10.

  Receiving the content request command, the server control unit 10 identifies the delivery destination from the service area information and sheet information that it has in advance, and sends the content data to the wireless terminal 16-5 in column 4 via the AP 12. Start distribution.

  On the other hand, the wireless terminal 16-5 in the column 4 receives the data distributed from the server control unit 10 via the antenna, and provides the content distribution service to the passengers in the passenger seat 15-5 in the column 5. provide.

  By performing the above-described series of processes for each of the wireless terminals 16-1 to 16-N, a content distribution service is realized for all areas in the apparatus.

  FIG. 2 is an explanatory view of the aircraft fuselage as in FIG. 1, but shows a state where the AP 12 has failed. When the AP 12 breaks down, wireless service is not possible for the columns 4, 5, and 6 in the service area 2, so the content distribution service for passengers in the columns 5, 6, and 7 cannot be provided.

  Next, the antenna directivity and the service switching function, which are features of the present invention, will be described.

  FIG. 3 is a diagram for explaining an example of the directivity characteristics of the antenna. FIG. 3A shows the state of the APs 11 to 14 at the normal time (no failure). In this case, the directivity characteristics of the antennas of all the APs are in the same directivity characteristic A state, and all the APs provide a unicast service.

  FIG. 3B shows the state of the APs 11 to 14 when the AP 12 fails.

  The server control unit 10 that has detected that the AP 12 is malfunctioning refers to the management information included therein and uses the directivity characteristics of the antenna for the AP 11 by the passenger seated in the directivity characteristics A (rows 1 to 4). Change to directivity characteristic B (transmitted to wireless terminals 16-1 to 16-7 used by passengers seated in columns 1 to 7) Issue the command to

  “Directional characteristic A” means a directivity characteristic that emits radio waves in the direction of the wireless terminal in the service area serviced by the AP in normal times, and “Directional characteristic B” means that the service area is adjacent to the left (FIG. 3). The directional characteristic that emits radio waves in the direction of the service area of the AP (when viewed in Fig. 3) represents the direction of the service area of the AP that is adjacent to the right (as viewed in Fig. 3). Represents the directivity of emitting radio waves.

  Next, with respect to the plurality of wireless terminals 16-5 to 16-7 in the service area 2, the directivity characteristics CB (radio waves from the AP 11) to the directivity characteristics CA (receives radio waves from the AP 12) of the antenna on the wireless terminal side are received. To change the content distribution service in the service areas 1 and 2 provided by the AP 11 from the unicast service to the multicast service.

  The “directional characteristic CA” refers to a directivity characteristic in which an antenna is directed in the direction of an AP that delivers radio waves to a service area to which the self belongs, and the “directive characteristic CB” refers to a service area to which the self belongs. The antenna is pointed in the direction of the AP adjacent to the left of the AP that delivers radio waves (see Fig. 4). The directional characteristic CC refers to an AP that delivers radio waves to the service area to which it belongs in normal times. The antenna is directed to the AP direction on the right side (see FIG. 5), and represents the directivity. Further, AP 13 may cover service area 2 instead of AP 11 covering service area 2.

  When the AP 13 covers the service area 2, it is as follows. FIG. 3C shows the state of the APs 11 to 14 when the AP 12 fails and the AP 13 covers it.

  The server control unit 10 that has detected that the AP 12 has failed refers to the management information in the inside, and the antenna directivity is used by the passenger seated in the directivity A (rows 8 to 10) with respect to the AP 13. Directional characteristics C (transmitted to radio terminals 16-5 to 16-10 used by passengers seated in columns 5 to 10) Issue the command to

  Next, for the plurality of wireless terminals 16-5 to 16-7 in the service area 2, the directivity characteristic CC (receives the radio wave from AP12) of the antenna on the wireless terminal side to the directivity characteristic CC (the radio wave from AP13). To change the content distribution service in the service areas 2 and 3 where the AP 13 starts the service from the unicast service to the multicast service.

  Here, the reason why the content distribution service is switched will be described. For example, when the maximum transmission bandwidth of one AP is 60 Mbps, when unicast service for three rows of passenger seats is to be implemented, unicast service for up to 30 people (10 seats × 3 rows) is required. . Further, when the service bandwidth per passenger is 2 Mbps, a bandwidth of at least 60 Mbps is required.

  Reason 1) If AP11 or AP13 tries to provide a unicast service to passengers of AP12, a bandwidth of 2 Mbps (service band) × 60 (10 seats × 6 seats), that is, 120 Mbps is required. , 13 is exceeded.

  Reason 2) In order to avoid this, it is possible to degrade the service bandwidth per passenger to 1 Mbps. In this case, the server control unit 10 needs to have the same content data of 2 Mbps and 1 Mbps. Yes, the image quality deteriorates.

  Therefore, in the embodiment of the present invention, instead of the unicast service, a unicast distribution that solves the above-mentioned problems is aimed at providing a multicast service for content distribution of 30 CH at 2 Mbps for one content without deterioration of image quality. Switching between service and multicast distribution service.

  Reason 3) The output power on the AP side needs to be changed due to the problem that the communication distance becomes longer by changing the service area to be covered. In this case, in the unicast distribution service, there are frequent concerns about interference with other service areas due to frequent occurrence of UPLINK and DOWNLINK in the transmission path. Therefore, for the purpose of reducing the UPLINK between the wireless terminals, the multicast service is changed to one in which no UPLINK occurs.

  4 and 5 are explanatory views of the passenger seat 15 and the wireless terminal 16 in the service areas 1, 2, and 3 as seen from above. FIG. 4 corresponds to the case of FIG. 3B, and FIG. 5 corresponds to the case of FIG. The left side of FIG. 4 shows an example of antenna directivity in each wireless terminal when there is no AP failure.

  Each wireless terminal has optimum directivity and polarization characteristics for APs in each service area, thereby realizing more stable wireless communication and suppressing jamming to other service areas. It is characterized by that.

  On the other hand, the right side of FIG. 4 shows the state in the service areas (service area 1, service area 2, service area 3) of APs 11, 12, and 13 when AP 12 fails. The server control unit 10 that has detected that the AP 12 is out of order refers to the management information included therein, and issues a command for changing the antenna directivity from the directivity A to the directivity B to the AP 11.

  Next, a command for changing the antenna directivity of each wireless terminal from the directivity CA to the directivity CB is issued to all the wireless terminals 16 in the service area 2, and the content distribution service in the service area of the AP 11 is issued. Switch from unicast service to multicast service.

  The left side of FIG. 5 shows an example of antenna directivity characteristics in each wireless terminal when there is no AP failure. Each wireless terminal has optimum directivity and polarization characteristics for APs in each service area, thereby realizing more stable wireless communication and suppressing jamming to other service areas. It is characterized by that. On the other hand, the right side of FIG. 5 shows a state in the service area of the APs 11, 12, and 13 when the AP 12 fails.

  The server control unit 10 that has detected that the AP 12 is out of order refers to the management information included therein, and issues a command for changing the antenna directivity from directivity A to directivity C to the AP 13.

  Next, a command for changing the antenna directivity of each wireless terminal from the directivity CA to the directivity CC is issued to all the wireless terminals in the service area 2, and the content distribution service in the service area of the AP 13 is issued. Switch from unicast service to multicast service.

  Next, details of operations of the server control unit 10, the APs 11 to 14, and the wireless terminals 16-1 to 16-N when an AP failure occurs will be described with reference to FIGS.

  FIG. 6 is an explanatory diagram of a configuration of a part related to control at the time of AP failure of the server control unit 10 according to the first embodiment of the present invention. The server control unit 10 includes a failure detection unit 21, a failure state storage unit 22, a directivity change unit 23 and a service change unit 24.

  The failure detection means 21 detects an AP failure. The failure detection method may automatically detect AP failures, or when a crew member notices a failure, the crew member presses a button and inputs information indicating that the failure has occurred. The means 21 may be used.

  When the failure detection means 21 detects a failure, information indicating the failure is stored in the failure status storage means 22. The contents of the failure status storage means 22 are transmitted to the directivity changing means 23 and the service changing means 24. The directivity changing unit 23 can transmit an instruction to change the directivity to the APs 11 to 14.

  Further, the service changing unit 24 can transmit an instruction to change the service (an instruction to change to multicast or an instruction to change to unicast) to the APs 11 to 14.

  In accordance with instructions from the directivity changing unit 23 and the service changing unit 24, the APs 11 to 14 change the antenna directivity and change the service.

  10 and 11 are explanatory diagrams of an example of the management table 1. 10 and 11 show the stored contents of the failure status storage means 22. FIG. 10 shows a state immediately after the AP 12 failure is detected and before the AP to be covered is determined. FIG. 11 shows a state where the AP 12 has failed and the AP 13 covers it.

  In the “AP number” column, a symbol identifying the AP is recorded, and in the CH column, the number of wireless terminals that serve when the AP is normal is recorded.

  In the “service” column, information indicating whether the current service is multicast or unicast is recorded. “AVOD” indicates a unicast state, and “Multicast” indicates a multicast state.

  In the “status” column, information indicating whether or not the AP is operating normally is recorded. “Alive” indicates that the device is operating normally, and “Dead” indicates that the device is not operating normally.

  The column “Power” records the strength of the radio wave output from the AP. “Low” indicates the strength that radio waves reach the wireless terminal in the service area served by the AP in normal times, and “Middle” indicates the strength that radio waves reach the wireless terminal in the adjacent service area. ing.

  The “AP” column in the “directivity pattern” records the directivity of the radio wave output by the AP. “A” indicates that the radio wave is emitted in the direction of the wireless terminal in the service area served by the AP in normal times, and “B” indicates the service of the AP that is adjacent to the left of the own service area (as viewed in FIG. 4). “C” indicates that radio waves are emitted in the direction of the service area of the AP on the right side (as viewed in FIG. 4).

  In the “Client” column in the “Directivity pattern”, the directivity of the receiving antenna of the wireless terminal in the service area serviced by the AP is recorded in the normal state. “CA” indicates that the antenna is directed in the direction of the AP that delivers the radio wave to the service area to which the self belongs, and “CB” is adjacent to the left of the AP that delivers the radio wave to the service area to which the self belongs. “CC” indicates that the antenna is directed to a certain AP direction (see FIG. 4), and “CC” is directed to the AP direction right next to the AP that delivers radio waves to the service area to which the self belongs in normal times (see FIG. 5). It shows that.

  Record the seat class (first class, business class, economy class, etc.) in the service area in the “Class” column. The management table shown above is an example, and the present invention is not limited to these.

  FIG. 12 is an explanatory diagram of an example of a management table in cover AP determination. The management table illustrated in FIG. 12 is for the purpose of determining the directivity of the AP and the service content by the directivity changing means 23 and the service changing means 24 after the AP has failed. Used.

  In the “failed AP” column, an identification symbol of an AP that is supposed to fail is recorded.

  In the “Cover AP” column, the identification code of the AP that can cover the AP recorded in the case of failure and the class of the service area (first class, business class, economy class, etc.) are recorded. The

  In the “service” column, a service performed by the AP when the AP recorded in the failed AP column covers is recorded. “Multicast” indicates multicast, and “AVOD (Multicast)” indicates that AVOD service is performed by multicast.

  In the “Power” field, the strength of the radio wave output by the AP recorded in the cover AP field is recorded. “Middle” indicates the strength that the wireless terminal in the service area of the adjacent AP can receive.

  The directivity of the AP recorded in the cover AP column is recorded in the “AP” column in the “directivity pattern”. “B” indicates a directivity (FIG. 3B) in which radio waves reach the wireless terminal in the service area of the normal AP and the AP service area on the right side, and “C” indicates the service area of the normal service area. The directivity (FIG. 3 (c)) that the radio wave reaches the wireless terminal in the service area of the AP on the left is shown.

  In the “Client” column in the “Directivity pattern”, the directivity of the wireless terminal in the service area where the AP described in the failed AP column normally serves is recorded. “CB” indicates that the antenna is directed in the AP direction on the left side of the AP that delivers radio waves to the service area to which the self belongs (see FIG. 4), and “CC” indicates the service area to which the self belongs in normal times. On the other hand, it indicates that the antenna is directed in the AP direction on the right side of the AP that delivers the radio wave (see FIG. 5).

  FIG. 7 is a flowchart for explaining the operation of the failure detection means in the server control unit 10 according to Embodiment 1 of the present invention.

  The failure detection means 21 issues an Alive check command in order to confirm the state of each AP (step S51).

  Thereafter, it is determined whether or not there is a response within a certain period (step S52).

  (1) When there is a response from the AP, it operates as follows.

  The management table information as shown in FIG. 10 is updated to “Alive” (step S53).

  When there is no failure in the AP, the Alive check and the management table update as described above are repeated at regular intervals.

  (2) When there is no response from the AP, the operation is as follows.

  An AP that does not respond is determined to have failed, and “Dead” is written as shown in FIG. In the case of FIG. 10, “Dead” is written in the status column of the AP 12 row when the AP 12 fails. Thereafter, the cover AP is determined with reference to the management table information shown in FIG. 12 (step S54).

  This determination procedure will be described in detail with reference to FIG. For example, when the AP 12 fails, AP11 and AP13 are candidates as the cover AP. When the service area class of each AP is confirmed, AP11 is a business class and AP13 is an economy class. In general, the specifications may vary from airline to airline, but usually there are many airlines that offer the best service for business class and first class passengers. There are many cases in which a decline in function is not desirable.

  Therefore, there is a mechanism that can be set separately, and for APs that provide services for the first class and business class, the priority from the cover APs can be lowered or excluded from the cover AP list. The airline may be adapted to the specifications for each airline. At this time, as a process in a case where the priority of the AP providing the service to the first class or the business class is lowered, the AP 13 determines to cover the service area of the AP 12.

  Next, a change in service is notified to passengers in the service area 3 according to the management table information. Thereafter, the directivity changing means 23 issues a change command of the output power of the AP and a directivity pattern command for changing the antenna directivity of the AP to the AP 13. Further, the service changing unit 24 issues an AP service change command to the AP 13 (step S55).

  Next, a directivity pattern command for changing the client antenna directivity according to the management table information is issued to each wireless terminal in the service area 2 of the conventional AP 12 via the AP 13 (step S56). Thereafter, the content data service is started (step S57), and the management table is updated as shown in FIG. 11 (step S53).

  Next, details of the operation of the adjacent AP when the AP fails will be described with reference to FIG. FIG. 8 is a flowchart for explaining the operation of the AP.

  Control commands and content data are received from the directivity changing means 23 and the service changing means 24 (step S61). Next, it is determined whether the command is an Alive command (step S62). If the received data is an Alive command (“YES”), ACK is transmitted to the server control unit 10 as a response to the server control unit 10 (step S63).

  On the other hand, if the received data is other than the Alive command (in the case of “NO”), it is determined whether or not it is an antenna switching command (step S64). When the command from the directivity changing means 23 is a switching command (in the case of “YES”), a process of switching the antenna directivity characteristics of the AP is performed according to information included in the switching command (step S65). Thereafter, a command for switching the antenna directivity on the client side is issued to the client side in accordance with the information included in the switching command from the server control unit 10 (step S66).

  In step S62 and step S64, when the received data is neither an Alive command nor a switching command (in the case of “NO”), content data and control data are transmitted to a plurality of wireless terminals connected to the AP. Is performed (step S67).

  Finally, the detailed operation on the client side (wireless terminal side) will be described with reference to FIG. FIG. 9 is a flowchart for explaining the operation of the wireless terminal.

  After receiving data from the AP (step S71), it is determined whether the data is a switching command (step S72).

  In the case of content data or control data (in the case of “NO”), processing for displaying the data on the monitor is performed (step S73).

  Then, when the received data is a switching command (in the case of “YES”), the directivity characteristics of the antenna on the client side are switched according to the antenna switching information (step S74).

  As described above, when an AP fails in the wireless communication service area, the AP adjacent to the service area of the failed AP covers the service area of the failed AP.

  At this time, by changing the directivity characteristics of the antenna of the adjacent AP that covers the service and the directivity characteristics of the antenna on the client side, the service to be provided is changed from the unicast service to the multicast service. It is possible to provide a wireless communication service to the failed area. Further, by switching the directivity, it is possible to prevent interference with other terminals and a decrease in communication efficiency.

(Embodiment 2)
In the first embodiment, the case where one AP has failed is described. In the second embodiment, the case where two APs fail is described. The second embodiment of the present invention will be described below with reference to FIGS. 13 (a) and 13 (b).

  FIG. 13A shows a normal state in which no AP has failed. Here, when the AP 11 and the AP 13 fail, if the AP 12 covers the service area 1 served by the AP 11 and the service area 3 served by the AP 13 is covered by the AP 14, there is no service area where the service cannot be provided.

  In this case, a multicast service is provided in four service areas. However, if the AP 12 covers both the service area 1 and the service area 3 as shown in FIG. 13B, there are three service areas that are multicast services, and it is possible to further suppress a decrease in service.

  As described above, when a plurality of APs have failed, a combination with one or a plurality of APs that cover the service area of the failed AP is selected, and a combination that has less influence on passengers is selected. By covering the service area of the failed AP, it is possible to suppress a decrease in the overall service.

In addition, the following method can be considered as a method of selecting one or a plurality of APs.
1) A method for selecting a combination with the smallest number of one or a plurality of APs 2) A method for prioritizing APs and preferentially selecting APs with higher priorities 3) Weighting APs ( Method of selecting the combination that minimizes the sum of the weights of one or more APs to be selected by selecting a combination that represents a decrease in customer satisfaction due to changing the service from multicast to unicast) Perform the first weighting (a number that represents a drop in customer satisfaction due to changing the service from multicast to unicast) and a second weight (a number that represents a drop in customer satisfaction due to service interruption) .

Thereafter, the method of selecting the combination that minimizes the sum of the first weighted sum of the weights of the one or more APs to be selected and the second weighted sum of the service areas that remain unserved 5) above 3, In 4, the method of setting the weighting so that it is proportional to the number of people served by each AP. In the above, the numerical values that increase as the customer satisfaction level decreases. However, the present invention is not limited to this. The numerical values that decrease as the degree decreases may be summed, and the AP may be selected so that this value is maximized.

In the fifth method of selecting an AP, the “number of people to serve” includes the following meanings.
(A) When the AP is selected, the number of serving wireless terminals is the number of persons to be serviced. (B) The number of seats the passenger is scheduled to board is the number of serving persons. (C) If the user wants to use In the case of (A), the AP can be selected in accordance with the actual usage situation when the number of operating wireless terminals (that is, the number of serviceable wireless terminals) is the number of users.

  In the case of (B), an AP can be selected in anticipation of the usage situation in a state before the use of the wireless terminal starts.

  In the case of (C), when the passengers are expected to increase soon after they are seated, or when a new passenger is scheduled to enter at an airport or station on the way, An AP can be selected assuming a case (a case where everyone uses the service).

  In the second embodiment, the embodiment has been described in which an AP that automatically covers a faulty AP is selected based on prestored information, actual usage, and the like. However, the present invention is not limited to this. Absent. For example, the crew member may be notified that the AP has failed, the candidate APs that cover the selectable broken AP may be shown, and the crew member may select from the candidates.

  Further, not only the candidate APs that can be selected, but also information on the effects of switching the AP to multicast, such as the above-mentioned weighting information and the number of people serving, are displayed. You may choose from.

(Embodiment 3)
In the first embodiment and the second embodiment, the case has been described in which the faulty AP and the service area of the AP that covers the same are all multicast. However, in the third embodiment, unicast is performed for some wireless terminals. The case where the service is performed will be described. Hereinafter, Embodiment 3 of the present invention will be described with reference to FIG.

  The point where the AP 12 covers the service areas of the AP 11 and the AP 13 is the same as that of the second embodiment. However, the AP 12 provides some wireless terminals in the service areas 1 to 3 where the multicast service is performed. Unicast service. The target of unicast service is provided to users who have a high need for a separate service in the service area where multicast service is performed.

  For example, if the majority of the service area understands Japanese, and only some people can understand Japanese if they do not understand Japanese, they will be able to service Japanese programs via multicast and do not understand Japanese For those of you, we offer English-language programs through unicast.

  For example, when a match between team A and team B is relayed, a program with commentary for team A fans will be serviced by multicast, and a program with commentary for team B fans by unicast only to some people. Service.

  If there is a vacant seat in the service area of the AP 14 or there is a person who is not using the service and there is a vacant AP 14 service band, the vacant area with the service area 3 from the AP 14 is utilized as shown in FIG. Unicast service can be provided to the terminal. In this case, the directivity may be changed so that only the wireless terminal receiving the unicast service can easily receive the radio wave from the AP 14. In this way, it is possible to prevent radio waves from the AP 12 from being mixed into the wireless terminal that receives the unicast service in the service area 3.

  In the third embodiment, the unicast service is performed using the free bandwidth of the AP that is performing the unicast service. However, the present invention is not limited to this. For example, a unicast band may be made available without using all bands in a multicast service, and the band may be used when a unicast service is required.

  The wireless communication system of the present invention can be used for information delivery systems such as aircraft, vehicles, ships, etc., and systems for delivering content such as video and audio.

Explanatory drawing of the aircraft fuselage part of the wireless communication system of Embodiment 1 of the present invention Explanatory drawing of the aircraft fuselage when the AP that provides the wireless communication service in the wireless communication system fails (A) An explanatory diagram of an example of antenna directivity characteristics of an AP in a system that performs a wireless communication service according to Embodiment 1 of the present invention. (B) An adjacent AP has a service area of a failed AP according to Embodiment 1 of the present invention. An explanatory diagram of an antenna directivity characteristic example of an adjacent AP when covering (when AP11 is covering) (c) Antenna directivity of the adjacent AP when the adjacent AP covers the service area of the failed AP according to Embodiment 1 of the present invention Illustration of characteristic example (when AP13 is covered) An explanatory diagram of an example of antenna directivity characteristics of all wireless terminals in the service area when there is no AP failure and when there is a failure (when AP 11 is covered) An explanatory diagram of an example of antenna directivity characteristics of all wireless terminals in the service area when there is no AP failure and when there is a failure (when AP 13 is covered) Explanatory drawing of a structure of the part relevant to the control at the time of AP failure of the server control part in Embodiment 1 of this invention Flow chart for explaining the operation of the failure detection means in the server control unit Flowchart explaining operation of AP Flow chart explaining operation of wireless terminal Illustration of an example of a management table Illustration of an example of a management table Explanatory drawing of an example of the management table in cover AP determination (A) An explanatory diagram of an example of antenna directivity characteristics of an AP in a system performing a wireless communication service according to the second embodiment of the present invention. (B) When a neighboring AP covers the service area of a failed AP according to the second embodiment. (C) An explanatory diagram of an example of antenna directivity of an AP in a system that provides a wireless communication service according to the third embodiment of the present invention

Explanation of symbols

10 Server control unit 11, 12, 13, 14 AP
15-1 to 15-N Passenger seat 16-1 to 16-N Wireless terminal 21 Failure detection means 22 Failure status storage means 23 Directivity changing means 24 Service changing means

Claims (11)

A plurality of radio base stations;
A wireless terminal that receives services from the wireless base station;
A distribution server connected by wire to the wireless base station;
Means for detecting a failure of the radio base station;
Failure status storage means for storing a failure status of the radio base station;
Directivity changing means for changing the radiation directivity of radio waves of the radio base station;
A wireless communication system, comprising: service changing means for changing a communication service of the wireless base station from unicast to multicast. The directivity changing means expands the radiation directivity of a radio base station adjacent to the failed radio base station to the service area of the failed radio base station,
The wireless communication system according to claim 1, wherein the service changing unit changes the service of the adjacent wireless base station whose service area is expanded from unicast to multicast. 3. The wireless communication according to claim 1, further comprising means for changing the radiation directivity of the radio terminal in response to the radiation directivity of the radio base station. system. The radio base station is selected according to a predetermined priority among the radio base stations that can be covered when there are a plurality of radio base stations that can cover the failed radio base station. The wireless communication system according to any one of claims 1 to 3. When there are a plurality of radio base stations capable of covering a failed radio base station, a radio base station with few radio terminals in service among the radio base stations that can be covered is preferentially selected. The wireless communication system according to any one of claims 1 to 3. When there are a plurality of radio base stations that can cover a failed radio base station, the radio base stations that have few radio terminals scheduled to be serviced are preferentially selected from the radio base stations that can be covered. The wireless communication system according to any one of claims 1 to 3. When there are a plurality of radio base stations capable of covering a failed radio base station, a radio base station with few serviceable radio terminals among the radio base stations capable of being covered is preferentially selected. The wireless communication system according to any one of claims 1 to 3. The radio base station selected by a crew member is selected from the radio base stations that can be covered when there are a plurality of radio base stations that can cover the failed radio base station. The wireless communication system according to any one of the above. When two radio base stations fail, if there is a radio base station that can be covered by any of the two faulty radio base stations, broadcast of any one of the radio base stations The radio communication system according to any one of claims 1 to 3, wherein the directivity is expanded to a service area of two radio base stations that have failed and the service is changed to multicast. The radio communication system according to any one of claims 1 to 3, wherein a unicast service is performed for a part of radio terminals in a service area whose service is changed to multicast. When there are a plurality of combinations of radio base stations that cover a failed radio base station, an evaluation value for evaluating the combination of each radio base station is obtained, and a combination of radio base stations that maximizes or minimizes the evaluation value is selected. The wireless communication system according to claim 1, wherein the wireless communication system is a wireless communication system.

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