JP2017060141A - Radio communication program, radio communication method, radio base station, and radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication program and the like capable of accurately transmitting information.SOLUTION: A radio communication program makes a computer execute each of the following processing. The radio communication program transmits information for a ship positioned in a predetermined area, using a first transmission condition. The radio communication program receives response signals including the presence/absence of occurrence of an error in response to the information, from a plurality of ships positioned in the predetermined area. The radio communication program, when having received the response signals, calculates one or more values of the average value of the magnitude of field intensity and an error occurrence rate with respect to the information, of the response signals from the respective ships of the plurality of ships. The radio communication program, when the average value of the magnitude of field intensity is lower than a predetermined reference or when the error occurrence rate is higher than a predetermined reference, performs control of transmitting information using a second transmission condition differing from the first transmission condition.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless communication program, a wireless communication method, a wireless base station, and a wireless communication system.

  Conventionally, communication between a ship navigating at sea and a base station on land is performed by communication using a short wave band using ionospheric reflection or satellite communication using an artificial satellite. In a small ship, for example, a fishing boat, position information is reported at regular intervals using a short-band fishery radio to a fishery radio association that has jurisdiction over the fishing ship, which is an example of a base station. In addition, various information such as weather information is periodically transmitted from the Fisheries Radio Association to the fishing boat.

JP-A-6-105901 International Publication No. 2009/001552 JP 2004-266739 A

  However, in communication using the short wave band, radio waves from the base station may not reach the ship depending on radio wave propagation conditions, or errors may occur and information may be lost. For this reason, when simultaneously transmitting information from a base station to a plurality of ships located in an area, the base station receives the reception status of each ship in the area so that the base station In some cases, it may be determined whether or not information has been transmitted. The base station retransmits information according to the reception status received from each ship, but if the radio wave propagation status is poor, for example, the retransmission cannot be completed within the time allotted for information transmission. There is a case. That is, the accuracy of communication deteriorates due to fluctuations in communication quality from the base station to the ship. This problem is not limited to ships, but there is a similar problem in areas where communication is difficult, such as deserts, mountainous areas, and depopulated areas. For example, there is a similar problem when confirming the safety of people or livestock in such difficult communication areas.

  In one aspect, the present invention provides a wireless communication program, a wireless communication method, a wireless base station, and a wireless communication system that can transmit information with high accuracy.

  In one aspect, a wireless communication program causes a computer to execute a process of transmitting information on a ship located in a predetermined area under a first transmission condition. Further, the wireless communication program causes the computer to execute a process of receiving a response signal including the presence / absence of an error with respect to the information from a plurality of ships located in the predetermined area. In addition, when the wireless communication program receives the response signal, the wireless communication program receives one or more of an average value of magnitudes of radio wave strengths of response signals from the vessels of the plurality of vessels and an error occurrence rate for the information. Causes the computer to execute processing for calculating the value of. Further, the wireless communication program stores the information in the first information when the average value of the radio field intensity is lower than a predetermined reference and when the error occurrence rate is one or more. A computer is caused to execute a process of performing transmission under a second transmission condition different from the transmission condition.

  Information can be transmitted with high accuracy.

FIG. 1 is a block diagram illustrating an example of a configuration of a wireless communication system according to an embodiment. FIG. 2 is a diagram illustrating an example of a message format. FIG. 3 is a diagram illustrating an example of the area information storage unit. FIG. 4 is a diagram illustrating an example of the transmission condition storage unit. FIG. 5 is a diagram illustrating an example of the reception status storage unit. FIG. 6 is a diagram illustrating another example of a message format. FIG. 7 is a sequence diagram illustrating an example of the operation of the wireless communication system according to the embodiment. FIG. 8 is a diagram illustrating an example of a computer that executes a wireless communication program.

  Hereinafter, embodiments of a wireless communication program, a wireless communication method, a wireless base station, and a wireless communication system disclosed in the present application will be described in detail based on the drawings. The disclosed technology is not limited by the present embodiment. Further, the following embodiments may be appropriately combined within a consistent range.

  FIG. 1 is a block diagram illustrating an example of a configuration of a wireless communication system according to an embodiment. A wireless communication system 1 illustrated in FIG. 1 includes a ship 5 and a base station 100. The ship 5 has a communication terminal 10. In FIG. 1, one of the plurality of ships 5 and one of the plurality of base stations 100 are illustrated, but the number of the ships 5 and the base stations 100 is not limited. Any number of ships 5 and base stations 100 may be included.

  The communication terminals 10 of the plurality of ships 5 and the plurality of base stations 100 are connected to each other so as to be able to communicate with each other by shortwave radio waves using the reflection of the ionosphere L. Further, the plurality of base stations 100 are connected to each other via a network (not shown) so as to communicate with each other. Any type of communication network such as the Internet, LAN (Local Area Network), and VPN (Virtual Private Network) can be adopted as such a network, regardless of whether it is wired or wireless. In addition, a server (not shown) that exchanges various information with each base station 100 is communicably connected to the network.

  Here, in the communication using the reflection of the ionosphere L, a situation where reception becomes difficult may occur. As an example of a situation in which reception is difficult, there is interference due to a fading phenomenon or the like, and occurrence of some errors. The fading phenomenon includes coherent fading, polarization fading, jump fading, absorptive fading, selective fading, and K-type fading. Coherent fading is fading caused by a path difference when there are a plurality of paths through which radio communication radio waves reach. Polarization fading is fading that occurs when the plane of polarization changes when radio waves are reflected on the ionosphere. Jumping fading is fading that occurs when radio waves are reflected by the ionosphere or penetrate through the ionosphere due to variations in the density of the ionosphere. Selective fading is fading that occurs when a band and an attenuation amount that are attenuated by a frequency selective medium in a radio wave transmission path vary with time. K-type fading is fading that occurs when the equivalent radius coefficient (K) of the earth fluctuates due to weather conditions or the like, and the bending of the radio wave transmission path fluctuates.

  The wireless communication system 1 is, for example, a fishing boat that operates in a sea area where the ship 5 is separated from the coast by 200 nautical miles or more, and the base station 100 is a base station that is installed in a fishery wireless association provided in the vicinity of a fishing port. In the wireless communication system 1, for example, in order to transmit various information to the plurality of ships 5, areas where the sea surface is divided by 1 degree of latitude and longitude are set. The base station 100 transmits various information to the ship 5 located in the area. In the following description, there is a case where the base station 100 broadcasts to a plurality of ships 5 located in a predetermined area, that is, the broadcast communication is called broadcasting.

  The base station 100 transmits information on the ship 5 located in a predetermined area under the first transmission condition. That is, the base station 100 is a radio base station that broadcasts information on the ship 5 located in a predetermined area under the first transmission condition. The first transmission condition is, for example, 19600 baud using a baud rate. When the communication terminal 10 of the ship 5 receives the information transmitted from the base station 100, the communication terminal 10 transmits to the base station 100 a response signal including the presence or absence of an error with respect to the information, that is, the presence or absence of an error. In the following description, the response signal is also expressed as an Ack (Acknowledgment) message or simply Ack. The response signal may include not only the presence / absence of an error but also an error rate based on the number of characters in the broadcast message of information.

  The base station 100 receives a response signal including the presence or absence of an error occurrence with respect to information from a plurality of ships 5 located in a predetermined area. When the base station 100 receives the response signal, the base station 100 calculates one or more values of the average value of the radio wave intensity of the response signal from each of the plurality of ships 5 and the error occurrence rate for the information. calculate. The base station 100 sets the information different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined reference and when the error rate is one or more. Control to transmit under the second transmission condition. In the following description, the average value of the radio field intensity may be expressed as an average value of the radio field intensity, and the error occurrence rate for information may be expressed as an error rate. Examples of the predetermined standard include a case where the response signal with an error is 50% or more among the response signals received from the target ship 5. The second transmission condition is, for example, 9600 baud whose modulation rate is lower than that of the first transmission condition. Thereby, the base station 100 can suppress the fluctuation | variation of communication quality with respect to the some ship 5 located in a predetermined area, and can transmit information accurately.

  Then, each component which comprises the radio | wireless communications system 1 is demonstrated. The communication terminal 10 includes a communication unit 11, a storage unit 12, a positioning unit 13, a display operation unit 14, and a control unit 15. Note that the communication terminal 10 may include various functional units included in a known computer other than the functional units illustrated in FIG. 1, for example, functional units such as various input devices and audio output devices. As an example of the communication terminal 10, a tablet terminal, a portable personal computer, or the like can be employed.

  The communication unit 11 is realized by, for example, a medium wave, short wave, or ultra high frequency band wireless device. The communication unit 11 is a communication interface that is wirelessly connected to any one or more of the plurality of base stations 100 via the ionosphere L and manages information communication with the base station 100. The communication unit 11 transmits an Ack message that is a response signal input from the control unit 15, management information including position information, and the like to the base station 100. Further, the communication unit 11 receives radio waves transmitted from the base station 100 and acquires various information such as broadcast telegrams.

  The communication unit 11 is one or more of 2 MHz band, 4 MHz band, 8 MHz band, 12 MHz band, and 16 MHz band, 30 MHz band, and 50 MHz band or more as a radio wave of medium to short wave or ultra high frequency band. A frequency band can be used. For example, the communication unit 11 uses a frequency band selected by the operator of the communication terminal 10 according to the distance from the land and the time zone. This is because the propagation state of radio waves in the medium wave, short wave, and ultra high frequency band is affected by the ionosphere L whose state varies depending on solar activity and day and night. In addition, the selection of the frequency calculates the distance to the representative base station 100 based on the position information obtained by positioning by the positioning unit 13, and weights each frequency according to the calculated distance, season, and time. It is possible to select a frequency with higher reachability. The frequency is selected in consideration of the band characteristics of each frequency band.

  The communication unit 11 can use digital modulation such as PSK (Phase Shift Keying) and FSK (Frequency Shift Keying) as a modulation method. Further, the communication unit 11 can use a modulation scheme such as PSK31 in a low frequency band. For example, PSK31 has a low communication speed of 31 baud but has a narrow exclusive band and is suitable for data communication in a short wave band for mainly communicating text data. Note that the communication unit 11 uses, for example, serial communication using RS-232C for control of the communication unit 11 as a connection method with the control unit 15, and voice input / output for data exchange such as various information. A modulation signal can be input and output using a terminal.

  The storage unit 12 is realized by, for example, a semiconductor memory device such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk or an optical disk. The storage unit 12 stores various information included in the response signal, information used for processing in the control unit 15, and the like.

  The positioning unit 13 receives a signal from the satellite positioning system. The positioning unit 13 performs positioning by receiving signals from a global navigation satellite system such as GPS (Global Positioning System), GLONASS (Global Navigation Satellite System), Galileo, and compass as satellite positioning systems. The positioning unit 13 performs positioning when positioning is requested by the control unit 15, and outputs the positioning result as position information based on a geodetic system such as a WGS (World Geodetic System) 84. In addition, if the positioning unit 13 is requested by the control unit 15 to continue positioning, the positioning unit 13 continuously performs positioning and continues to output position information until the control unit 15 requests to stop. The positioning unit 13 receives signals from a quasi-zenith satellite system, an Indian regional navigation satellite system, DORIS (Doppler Orbitography and Radio-positioning Integrated by Satellite), and a regional navigation satellite system such as Hokuto as a satellite positioning system. May be.

  The display operation unit 14 is a display device for displaying various types of information and an input device for receiving various types of operations from the user. For example, the display operation unit 14 is realized by a liquid crystal display or the like as a display device. Further, for example, the display operation unit 14 is realized by a touch panel or the like as an input device. That is, in the display operation unit 14, the display device and the input device are integrated. Moreover, the display operation part 14 displays a keyboard as a user interface, for example in the lower part of a screen, and receives key input. The display operation unit 14 outputs an operation input by the user to the control unit 15 as operation information.

  The control unit 15 is realized, for example, by executing a program stored in an internal storage device using a RAM as a work area by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like. The control unit 15 may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The control unit 15 controls the entire communication terminal 10. In addition, the control unit 15 obtains position information from the positioning unit 13 at least three times a day, for example, for deemed GMDSS (Global Maritime Distress and Safety System), and manages information including the obtained position information, The data is transmitted to the base station 100 via the communication unit 11. The GMDSS is a wireless communication system that is required to be installed on ships with a gross tonnage of 20 tons or more. For fishing boats with a gross tonnage of less than 20 tons, the “deemed GMDSS” reports position information three times a day. , GMDSS installation is exempted.

  The control unit 15 requests the positioning unit 13 to perform positioning. The control unit 15 outputs, as a positioning request, either a positioning request only once or a request to continue positioning continuously to the positioning unit 13. When the position information corresponding to the positioning request is input from the positioning unit 13, the control unit 15 inserts the position information into a message format and generates a message as management information. The control unit 15 outputs the generated message, that is, management information to the communication unit 11. Note that the control unit 15 may encrypt the position information so that the position information can be decrypted only by a device within the fishery wireless association to which the fishing boat on which the communication terminal 10 is installed belongs.

  Further, the control unit 15 may use TCG (Trusted Computing Group) technology to enable verification of information credibility and to realize secure transmission of information. Here, an example of the TCG technique will be described.

  Terminals and devices that communicate with the outside are always exposed to security threats, and unexpected modifications may be made to the software structure that constitutes the platform due to viruses, spyware, other malicious scripts, unauthorized access, and the like. For such risks, TCG realizes a safe computing environment by ensuring the reliability of the platform. Here, the platform indicates hardware, OS, application, and the like.

  For example, there is a limit to conventional security measures that depend on software against the threat of software tampering. For this reason, TCG embeds a TPM (Trusted Platform Module) chip (not shown) in the platform, and uses this TPM chip as a root of trust to construct a reliable computing environment that is extremely difficult to falsify. Further, by using the TPM chip, hardware-based data / certificate protection and a secure cryptographic processing environment can be realized.

  Next, the TPM chip will be described. The TPM chip is a birdware chip bound to an electronic device (for example, the communication terminal 10) and has tamper resistance. The TPM chip is physically bound to the main components of the electronic device so that it cannot be removed from the electronic device. For example, the component parts of the electronic device correspond to a motherboard or the like. Since the TPM chip is designed with the functions, memory area, and processor power to be minimized, it can be manufactured at low cost and can be applied to various electronic devices and platforms.

  For example, the functions of the TPM include a function for generating and storing an RSA (Rivest Shamir Adleman) secret key, and a function for signing, encrypting, and decrypting with an RSA secret key. In RSA, a pair of a private key and a public key is created. The TPM function includes a function for calculating a hash of SHA-1 (Secure Hash Algorithm 1) and a function for holding environment information of the electronic device. When the bound electronic device is activated, the TPM measures the software code in the boot process to the BIOS, OSloader, and OS kernel, hashs the measured software code, and registers it in a register inside the TPM. Further, the TPM collects hardware information of the bound electronic device, hashes the hardware information, and registers the hashed information in a register in the TPM.

  In the TCG technology, a software stack and a software interface are defined in order to use a TPM chip that is a hardware device from a higher-level application or library. This software stack is called TSS (TCG Software Stack), and is composed of software modules that store the functions of TPM chips whose resources are limited. The application of the electronic device can access the function of the TPM chip described above using the interface provided by the TSS. The TPM chip ensures the validity of hash value collection by managing the rules for collecting hash values with the TPM chip on the customer system side by hashing and adding a signature. Moreover, the TPM chip proves the non-falsification of the rule by checking the current rule and signature as necessary. That is, it becomes possible to verify the authenticity of processing and information related to the control unit 15. As a result, the TPM chip ensures that there is no falsification in the rules for collecting hash values by referring to the rules that have been proven to be non-falsified on the TPM chip side.

  Further, the control unit 15 may insert information hashed and signed by the TPM chip into a message format to generate a message that is management information. In this case, it is possible to verify the authenticity of processing and information related to the control unit 15 in the device (for example, the device in the fishery radio association to which the ship 5 belongs) that has received the generated electronic message.

  When a broadcast message that is information transmitted from the base station 100 is input from the communication unit 11, the control unit 15 extracts the broadcast information from the broadcast message, stores the information in the storage unit 12, and displays it on the display operation unit 14. Let The control unit 15 may store the broadcast message as a digitally sampled radio signal in the storage unit 12 and analyze the radio signal at each of a plurality of predetermined baud rates to extract broadcast information. In addition, the control unit 15 determines the presence / absence of an error in the broadcast message, and outputs an Ack message including the presence / absence of the error to the communication unit 11.

  FIG. 2 is a diagram illustrating an example of a message format. The message format 21 shown in FIG. 2 is an example of a message format for the communication terminal 10 to transmit management information used in deemed GMDSS. As shown in FIG. 2, for example, the message format 21 includes “Char code”, “format ver”, “Message Type”, “name of a vessel”, “Call Sign”, “nationality”, “prefectures”, “Geographic”. It has items such as “Point Location” and “Parity”. In the message format 21 of FIG. 2, for example, one cell is one byte. Further, the length of the message format 21 shown in FIG. 2 is 104 bytes as an example, but is not limited to this, and can be an arbitrary length. Further, the message format 21 may be provided with items corresponding to other various information.

  “Char code” indicates a character code system. “Format ver” indicates the version of the message format 21 and is an item for responding to the format change. “Message Type” indicates a message type, for example, a message type such as automatic, manual, request transmission, or emergency. “Name of a vessel” represents the ship name or identification information of the ship 5 in which the communication terminal 10 is installed. It should be noted that “name of a vessel” may represent the ship name and identification information of the ship 5 if the number of characters is sufficient. “Call Sign” represents the call sign of the radio station for reliable identification. “Nationality” is an abbreviation of “nationality registration” and represents a country of registration of a vessel. “Prefectures” represents the prefecture to which the affiliation belongs. “Geographic Point Location” indicates location information, and represents, for example, a positioning system, latitude, and longitude. “Parity” is a parity for confirming complete reception of the message.

  Returning to the description of FIG. 1, the base station 100 includes a communication unit 110, a storage unit 120, and a control unit 130. For example, the base station 100 has a radio device for each frequency band, and an antenna (not shown) is connected to each radio device, and communicates with the communication terminals 10 installed in the plurality of ships 5 at the same time in each frequency band. be able to.

  The communication unit 110 is realized by, for example, a radio wave of medium to short wave or ultra high frequency band. The communication unit 110 is realized by, for example, a NIC (Network Interface Card) or the like in order to communicate with another base station 100 and a server (not shown) via a network (not shown). The communication unit 110 is wirelessly connected to any one or more of the plurality of communication terminals 10 via the ionosphere L. That is, the communication unit 110 is a communication interface that manages communication of information between the communication terminal 10 and the base station 100. Note that the communication unit 110 connects to a network (not shown) by wire or wirelessly.

  The communication unit 110 is, for example, a plurality of wireless devices such as 2 MHz, 4 MHz, 8 MHz, 12 MHz, and 16 MHz, 30 MHz, and 50 MHz bands as medium to short wave or ultra high frequency band wireless devices. The radio waves transmitted from the communication terminal 10 are received using seven wireless devices corresponding to the ultra high frequency band. Moreover, the communication part 110 transmits an electromagnetic wave with respect to the communication terminal 10 using a some radio | wireless machine similarly to reception, for example. In addition, the frequency band to be used is determined according to any one or more of the position and time slot | zone of the fishing boat in which the communication terminal 10 is installed, for example. Further, the communication unit 110 uses a modulation method similar to that of the communication unit 11 of the communication terminal 10 as a modulation method. In addition, the communication unit 110 can use serial communication using RS-232C and data communication using a voice input / output terminal similarly to the communication terminal 10 for connection to the control unit 130.

  The communication unit 110 transmits, that is, broadcasts, a broadcast telegram input from the control unit 130 to the communication terminals 10 of a plurality of ships 5 located in a predetermined area under designated transmission conditions. In addition, the communication unit 110 extracts management information or an Ack message from the radio wave received from the communication terminal 10 and outputs the management information or the Ack message to the control unit 130. Further, the communication unit 110 outputs the radio wave intensity when the management information or the Ack message is received to the control unit 130.

  The storage unit 120 is realized by, for example, a semiconductor memory device such as a RAM or a flash memory, or a storage device such as a hard disk or an optical disk. The storage unit 120 includes an area information storage unit 121, a transmission condition storage unit 122, and a reception status storage unit 123. In addition, the storage unit 120 stores information used for processing in the control unit 130.

  The area information storage unit 121 stores a ship ID (Identifier) located in the area for each area, the number of ships, and the update date and time in association with each other. FIG. 3 is a diagram illustrating an example of the area information storage unit. As shown in FIG. 3, the area information storage unit 121 includes items such as “area ID”, “in-area ship ID”, “number of ships in area”, and “update date / time”. The area information storage unit 121 stores, for example, one record for each area ID.

  “Area ID” is an identifier for identifying an area for transmitting information. For example, the area ID is assigned to an area obtained by dividing the sea surface by 1 degree longitude and latitude. As the area ID, for example, an ID such as “N12E139” is assigned to an area of 12 degrees to 13 degrees north latitude and 139 degrees to 140 degrees east longitude. “In-area ship ID” is an identifier for identifying the ship 5 located in the area. “Number of ships in area” is information indicating the number of ships 5 located in the area. “Update date and time” is information indicating the date and time when the ship ID in the area and the number of ships in the area were updated. In the example of the first row in FIG. 3, the area ID “N12E139” indicates that there are “100” ships with the ship ID “S001, S002, S003..., S100”. In the example of the first line in FIG. 3, the date and time when the in-area ship ID and the number of ships in the area are updated is “June 17, 2015, 16:00”.

  Returning to the description of FIG. 1, the transmission condition storage unit 122 stores a list of transmission conditions specified for the communication unit 110 in association with the condition ID. FIG. 4 is a diagram illustrating an example of the transmission condition storage unit. As illustrated in FIG. 4, the transmission condition storage unit 122 includes items such as “condition ID”, “transmission condition”, “default use flag”, and “previous use flag”. The transmission condition storage unit 122 stores, for example, one record for each condition ID. The transmission conditions are set in advance by the administrator of the base station 100.

  “Condition ID” is an identifier for identifying a transmission condition. “Transmission condition” is information indicating a condition for setting the first transmission condition and the second transmission condition. The transmission condition can be, for example, a baud rate that is a modulation rate. The “default use flag” is a flag indicating a transmission condition set as an initial value of the first transmission condition. The “previous use flag” is, for example, a flag indicating the first transmission condition or the second transmission condition used when transmitting the previous broadcast message.

  In the example of FIG. 4, the condition ID “C01” is the transmission condition “19600 baud”, and the condition ID “C02” is the transmission condition “9600 baud”. The transmission condition “19600 baud” is the initial value of the first transmission condition because the default use flag is “Y”, and since the previous use flag is “Y”, it is used when the previous broadcast message is transmitted. Transmission conditions. The transmission condition may be a frequency at which a broadcast message is transmitted from the base station 100 to the communication terminal 10 and an error code correction method. Furthermore, the transmission condition may be a combination of a baud rate, a transmission frequency, and an error code correction method. Examples of error code correction methods include turbo codes and convolutional codes. In addition, as a transmission condition, a message with parity and a double message may be selectable.

  Returning to the description of FIG. 1, the reception status storage unit 123 stores information related to the Ack message received from the ship 5, information related to the broadcast message corresponding to the Ack message, and position information of the ship 5 in association with each other. FIG. 5 is a diagram illustrating an example of the reception status storage unit. As shown in FIG. 5, the reception status storage unit 123 includes “ship ID”, “Ack reception”, “error presence / absence”, “Ack radio wave intensity”, “Ack reception date / time”, “broadcast transmission frequency”, “broadcast ID”. ”,“ Position information ”, and“ location information reception date and time ”. The reception status storage unit 123 stores, for example, one record for each ship ID.

  “Ship ID” is an identifier for identifying the ship 5. “Ack reception” is information indicating whether or not an Ack message has been received from the ship 5. The Ack reception is, for example, “OK” when the Ack message can be received, and “NG” when the Ack message cannot be received. “Error presence / absence” is information indicating whether or not an error has occurred during reception of a broadcast message in the communication terminal 10 of the ship 5 when the Ack message has been received. The presence / absence of an error can be, for example, “none” when the number of error characters in the Ack message is zero, and “present” when the number of error characters is 1 or more.

  “Ack radio wave intensity” is information indicating the radio wave intensity when the communication unit 110 receives an Ack message. The Ack radio wave intensity can be expressed in, for example, five levels based on the electric field intensity. The Ack radio wave intensity is, for example, an electric field intensity of 30 dBμV / m or more when the electric wave intensity is “5”, an electric field intensity of 20 dBμV / m or more and less than 30 dBμV / m is an electric wave intensity of “4”, and an electric field intensity of 15 dBμV / m or more and less than 20 dBμV / m. It can be “3”. The Ack radio wave intensity can be, for example, an electric field intensity of 12 dBμV / m or more and less than 15 dBμV / m and an electric field intensity of 10 dBμV / m or more and less than 12 dBμV / m.

  “Ack reception date and time” is information indicating the date and time when an Ack message is received from the ship 5. In the example of the first line in FIG. 5, an Ack message was received from the ship ID “S001” at “17:17 on June 17, 2015” with the radio wave intensity “5”, and the error was “None”. It shows that.

  “Broadcast transmission frequency” is information indicating a frequency at which the base station 100 transmits a broadcast message corresponding to the Ack message. “Broadcast ID” is an identifier for identifying a broadcast message transmitted from the base station 100. The broadcast ID is used to identify to which broadcast message the Ack message is a response. In the example of the first line in FIG. 5, the base station 100 indicates that the broadcast message of the broadcast ID “H22001” is transmitted with “4.xxx MHz” to the area where the ship ID “S001” is located. That is, the example of the first line in FIG. 5 indicates that an Ack message has been received from the ship 5 with the ship ID “S001” in response to the broadcast message with the broadcast ID “H22001”.

  “Position information” is information indicating the position of the ship 5. The position information is, for example, position information that the base station 100 has received management information periodically transmitted from the ship 5 and extracted from the management information. The position information is information used to determine in which area the ship 5 is located. The “location information reception date / time” is information indicating the date / time when the location information is received.

  Returning to the description of FIG. 1, the control unit 130 is realized by executing a program stored in an internal storage device by using a RAM as a work area, for example, by a CPU, an MPU, or the like. The control unit 130 may be realized by an integrated circuit such as ASIC or FPGA, for example. The control unit 130 includes a communication control unit 131 and a calculation unit 132, and implements or executes information processing functions and operations described below. Note that the internal configuration of the control unit 130 is not limited to the configuration illustrated in FIG. 1, and may be another configuration as long as the information processing described below is performed.

  The communication control unit 131 receives management information from the communication terminals 10 of the plurality of ships 5 via the communication unit 110. Based on the position information included in the received management information, the communication control unit 131 stores the position information of each ship 5 and the reception date and time when the position information is received in the reception status storage unit 123 in association with the ship ID. To do. That is, the communication control unit 131 stores the position information of each ship 5 and the reception date / time of the position information that are periodically received in the reception status storage unit 123. The communication control unit 131 receives management information when it is transmitted from the communication terminal 10 at intervals of a predetermined time, for example, 3 hours. That is, the communication control unit 131 may receive the management information transmitted from the communication terminal 10 at an interval of less than a predetermined time, or may leave it without receiving it.

  The communication control unit 131 refers to the reception status storage unit 123 and identifies the ship ID of the ship 5 located in each area and the number of the ships 5 located in each area. That is, the communication control unit 131 compares the position information of the area set in advance with the position information of each ship 5 stored in the reception status storage unit 123, and the ship ID of the ship 5 located in each area. And the number of ships 5 located in the area. The communication control unit 131 associates the ship ID of the ship 5 located in each identified area, the number of ships located in the area, and the update date and time when the ship ID and the number of ships are updated with the area ID. The information is stored in the information storage unit 121.

  For example, when an instruction to broadcast certain information to a predetermined area is input from an operation unit (not shown) by the administrator of the base station 100, the communication control unit 131 generates a broadcast message based on the information. The communication control unit 131 refers to the transmission condition storage unit 122 and sets, for example, a transmission condition whose default use flag is “Y” as the first transmission condition. For example, the communication control unit 131 may set a transmission condition in which the previous use flag is “Y” as the first transmission condition. Note that if there is no “Y” in the previous use flag, the communication control unit 131 sets the transmission condition in which the default use flag is “Y” as the first transmission condition. In the example of FIG. 4, the default use flag is “Y” for the transmission condition “19600 baud” for the condition ID “C01”, and the previous use flag is “Y” for the transmission condition “19600 baud”. Therefore, “19600 baud” is set as the first transmission condition.

  When the first transmission condition is set, the communication control unit 131 transmits the generated broadcast message via the communication unit 110 to the ship 5 located in the designated area under the first transmission condition. When the transmission of the broadcast message is completed, the communication control unit 131 refers to the area information storage unit 121 and acquires the ship ID included in the in-area ship ID of the specified area. The communication control unit 131 stores the acquired ship ID in the reception status storage unit 123 in association with the broadcast ID of the broadcast telegram and the broadcast transmission frequency.

  The communication control unit 131 receives Ack messages from the plurality of ships 5 located in the designated area via the communication unit 110. Further, the Ack radio wave intensity, which is the radio wave intensity when the Ack message is received from the communication unit 110, is input to the communication control unit 131. The communication control unit 131 outputs the Ack message and the Ack radio wave intensity to the calculation unit 132. The communication control unit 131 stores the Ack reception availability, the Ack message error presence / absence, the Ack radio wave intensity, and the Ack reception date / time in the reception status storage unit 123 in association with the ship ID. The presence / absence of an error in the Ack message is “None” when the number of error characters in the Ack message is zero, and “Yes” when the number of error characters is 1 or more.

  When the average value and the error rate of the radio field intensity are input from the calculation unit 132, the communication control unit 131 receives at least one of a case where the average value of the radio field intensity is lower than a predetermined reference and a case where the error rate is high It is determined whether this is the case. For example, the predetermined standard may be “3” for the average value of the radio field intensity and “20%” for the error rate, but may be arbitrarily changed according to the importance of the information. . When the average value of the radio field intensity is lower than a predetermined standard and when the error rate is not one or more of the cases where the error rate is high, the communication control unit 131 transmits information to the ship 5 located in the area. Then, the information transmission process is terminated.

  When the average value of the radio field intensity is lower than a predetermined reference and when the error rate is one or more of the cases where the error rate is high, the communication control unit 131 determines whether or not the number of broadcast telegram transmissions exceeds a predetermined value. Determine whether. The predetermined value of the number of transmissions can be set to 5 times, for example. If the number of broadcast telegram transmissions exceeds a predetermined value, the communication control unit 131 ends the information transmission process, assuming that no further improvement in the information transmission rate can be expected in the current radio wave propagation situation. If the number of broadcast telegram transmissions does not exceed the predetermined value, the communication control unit 131 refers to the transmission condition storage unit 122 and sets a transmission condition that is more resistant to deterioration of radio wave propagation conditions as the second transmission condition. . For example, when the first transmission condition is “19600 baud”, the communication control unit 131 sets “9600 baud” as the second transmission condition. Further, the communication control unit 131 changes the previous use flag of the condition ID set as the second transmission condition in the transmission condition storage unit 122 to “Y”, and if the other use ID has the previous use flag “Y”. The generation information is added to the previous use flag of another condition ID, for example, “Y−1”. The generation information is referred to, for example, when returning to the previous transmission condition.

  When the second transmission condition is set, the communication control unit 131 transmits a broadcast telegram with the second transmission condition to the ship 5 located in the designated area via the communication unit 110. That is, the communication control unit 131 retransmits the broadcast message transmitted under the first transmission condition under the second transmission condition. The communication control unit 131 receives the Ack message corresponding to the broadcast message transmitted under the second transmission condition from the plurality of ships 5 located in the designated area via the communication unit 110. At this time, when the communication terminal 10 of the ship 5 transmits an Ack message without error to the broadcast message transmitted under the first transmission condition, the communication terminal 10 is transmitted under the second transmission condition in order to avoid interference. The Ack message corresponding to the broadcast message may not be transmitted. Further, the Ack radio wave intensity, which is the radio wave intensity when the Ack message is received from the communication unit 110, is input to the communication control unit 131. The communication control unit 131 outputs the Ack message and the Ack radio wave intensity related to the broadcast message with the second transmission condition to the calculation unit 132. The communication control unit 131 stores in the reception status storage unit 123 the Ack reception availability, Ack message error presence / absence, Ack radio wave intensity, and Ack reception date / time associated with the broadcast message of the second transmission condition in association with the ship ID.

  In addition, the communication control unit 131 determines the next time when the average value of the radio field intensity is higher than a predetermined reference and the error rate is one or more among the transmission messages of the second transmission condition. When sending the information, send back the transmission condition. That is, for example, the communication control unit 131 sets “19600 baud” as the first transmission condition at the first transmission and sets “9600 baud” as the second condition at the second transmission. When the average value and error rate of the radio wave intensity at the time of the second transmission is one or more of the cases where the average value of the radio wave intensity is higher than a predetermined reference and the error rate is low, The transmission condition at the third transmission is set to “19600 baud”. That is, the communication control unit 131 sets the transmission condition for the third transmission as the first transmission condition for the first transmission.

  When the Ack message and the Ack radio wave intensity are input from the communication control unit 131, the calculation unit 132, based on the Ack message and the Ack radio wave intensity, the average value of the radio wave intensity and the error rate at the communication terminal 10 of the ship 5 Is calculated. For example, the calculation unit 132 may calculate the average value of the radio wave intensity based on the number of the ships 5 located in the designated area, or based on the number of the ships 5 that have received the Ack message. An average value of the radio wave intensity may be calculated. For example, the calculation unit 132 calculates the error rate based on the presence or absence of an error in the Ack message received from the plurality of ships 5. For example, when the Ack message including no error is received from 60% of the ships 5 out of the number of ships located in the designated area, the calculation unit 132 can set the error rate to 40%. In other words, the calculation unit 132 calculates an error rate with respect to the ship 5 that cannot receive the Ack message as having an error. Note that the calculation unit 132 may calculate the error rate based on the number of ships that have received the Ack message. The calculation unit 132 outputs the calculated average value of radio field intensity and error rate to the communication control unit 131.

  When the Ack message and the Ack radio wave intensity related to the broadcast message of the second transmission condition are input from the communication control unit 131, the calculation unit 132 receives the average value of the radio wave intensity based on the Ack message and the Ack radio wave intensity, and The error rate at the communication terminal 10 of the ship 5 is calculated. For example, the calculation unit 132 refers to the reception status storage unit 123 and calculates the average value and error rate of the radio wave intensity based on the number of ships 5 located in the area. The calculation unit 132 outputs the calculated average value of radio field intensity and error rate to the communication control unit 131.

  Here, the format of the broadcast message and the Ack message will be described with reference to FIG. FIG. 6 is a diagram illustrating another example of a message format. As shown in FIG. 6, the broadcast message format 51 includes items such as “communication format information”, “base station ID”, “broadcast ID”, and “broadcast information”, for example. The “communication format information” is information indicating, for example, a character code system, a message format version, a message type, and the like. The “base station ID” is an identifier for identifying the base station 100 that transmits the broadcast message. “Broadcast ID” is an identifier for identifying a broadcast telegram. “Broadcast information” is information for the ship 5 located in a predetermined area.

  The Ack message format 52 includes items such as “communication format information”, “broadcast ID”, “ship ID”, “AckID”, and “number of error characters”, for example. The “communication format information” is information indicating, for example, a character code system, a message format version, a message type, and the like. “Broadcast ID” is an identifier that indicates which broadcast message the Ack message corresponds to and identifies the corresponding broadcast message. The “ship ID” is an identifier for identifying the ship 5 in which the communication terminal 10 that has transmitted the Ack message is installed. “AckID” is, for example, a number indicating the number of Ack messages for a broadcast message with a certain broadcast ID. That is, AckID is incremented by one every time a broadcast message having the same content is retransmitted and an Ack message is transmitted, for example. The AckID may be a number indicating how many times the Ack message is in one day, for example. The “number of error characters” is information indicating the number of character errors that occur in the broadcast message when the broadcast message corresponding to the Ack message is received, that is, the number of error characters. In the broadcast message format 51 and the Ack message format 52, a plurality of base station IDs, broadcast IDs, ship IDs, AckIDs, and the like may be inserted according to the length of the message. Thereby, it can retransmit about the part divided | segmented between ID.

  Next, the operation of the wireless communication system 1 according to the embodiment will be described. FIG. 7 is a sequence diagram illustrating an example of the operation of the wireless communication system according to the embodiment. In the following description, management information is periodically transmitted from the communication terminal 10 of the ship 5, and the area information storage unit 121 and the position information and position information reception date and time of the reception status storage unit 123 are updated as appropriate. It shall be.

  For example, when an instruction to broadcast certain information to a predetermined area is input by an administrator of the base station 100 from an operation unit (not shown), the communication control unit 131 of the base station 100 transmits a broadcast message based on the information. Generate. The communication control unit 131 refers to the transmission condition storage unit 122 and sets, for example, a transmission condition whose default use flag is “Y” as the first transmission condition. When the first transmission condition is set, the communication control unit 131 transmits the generated broadcast message to the ship 5 located in the designated area under the first transmission condition (step S1). When the transmission of the broadcast message is completed, the communication control unit 131 associates the broadcast ID of the broadcast message and the broadcast transmission frequency with the ship ID of the ship 5 located in the area, and receives the reception status storage unit 123. To remember.

  When receiving the broadcast telegram via the communication unit 11 (step S2), the control unit 15 of the communication terminal 10 installed in the ship 5 extracts broadcast information from the broadcast telegram and stores it in the storage unit 12 as well as the display. It is displayed on the operation unit 14. Moreover, the control part 15 determines the presence or absence of an error about a broadcast message | telegram, and transmits the Ack message | telegram containing the presence or absence of an error to the base station 100 via the communication part 11 (step S3).

  The communication control unit 131 of the base station 100 receives an Ack message from the plurality of ships 5 located in the designated area (step S4). Further, the Ack radio wave intensity is input from the communication unit 110 to the communication control unit 131. The communication control unit 131 outputs the Ack message and the Ack radio wave intensity to the calculation unit 132. The communication control unit 131 stores the Ack reception availability, the Ack message error presence / absence, the Ack radio wave intensity, and the Ack reception date / time in the reception status storage unit 123 in association with the ship ID.

  When the Ack message and the Ack radio wave intensity are input from the communication control unit 131, the calculation unit 132, based on the Ack message and the Ack radio wave intensity, the average value of the radio wave intensity and the error rate at the communication terminal 10 of the ship 5 Is calculated (step S5). The calculation unit 132 outputs the calculated average value of radio field intensity and error rate to the communication control unit 131.

  When the average value and the error rate of the radio field intensity are input from the calculation unit 132, the communication control unit 131 determines whether the average value of the radio field intensity is lower than a predetermined reference and / or the error rate is high. (Step S6). If the average value of the radio field intensity is not lower than the predetermined reference and / or the error rate is not higher (No at Step S6), the communication control unit 131 ends the information transmission process. Note that the communication control unit 131 has an average value of radio field intensity and an error rate related to the transmission message of the second transmission condition that is not lower than the predetermined standard and / or has a high error rate. If not, the transmission condition is returned when the next information is transmitted.

  If the average value of the radio field intensity is lower than the predetermined standard and / or the error rate is high (step S6: affirmative), the communication control unit 131 determines whether or not the number of broadcast telegram transmissions exceeds the predetermined value. Is determined (step S7). If the number of broadcast telegram transmissions exceeds a predetermined value (step S7: Yes), the communication control unit 131 ends the information transmission process. If the number of broadcast telegram transmissions does not exceed the predetermined value (step S7: No), the communication control unit 131 refers to the transmission condition storage unit 122 and sets a second transmission condition that is more resistant to deterioration of radio wave propagation conditions. Set to the transmission condition. When the second transmission condition is set, the communication control unit 131 transmits a broadcast message to the ship 5 located in the designated area under the second transmission condition (step S8).

  When receiving the broadcast telegram via the communication unit 11 (step S9), the control unit 15 of the communication terminal 10 installed in the ship 5 extracts broadcast information from the broadcast telegram and stores it in the storage unit 12 and displays it. It is displayed on the operation unit 14. Moreover, the control part 15 determines the presence or absence of an error about a broadcast message | telegram, and transmits the Ack message | telegram containing the presence or absence of an error to the base station 100 via the communication part 11 (step S10).

  The communication control unit 131 of the base station 100 receives the Ack message corresponding to the broadcast message transmitted under the second transmission condition from the plurality of ships 5 located in the designated area (step S11). In addition, the Ack radio wave intensity is input to the communication control unit 131. The communication control unit 131 outputs the Ack message and the Ack radio wave intensity related to the broadcast message with the second transmission condition to the calculation unit 132. The communication control unit 131 stores the Ack reception availability, the Ack message error presence / absence, the Ack radio wave intensity, and the Ack reception date / time associated with the broadcast message of the second transmission condition in the reception status storage unit 123 in association with the ship ID. Return to S5. As a result, when the base station 100 transmits information to a plurality of ships 5 at the same time and the error rate exceeds a predetermined value, the base station 100 changes the transmission conditions and retransmits to the ship 5 in which a failure or error has occurred. Therefore, highly accurate communication can be performed while suppressing radio wave interference. In other words, the base station 100 can transmit information with high accuracy while suppressing fluctuations in communication quality with respect to a plurality of ships 5 located in a predetermined area.

  As described above, the base station 100 transmits information on the ship 5 located in a predetermined area under the first transmission condition. In addition, the base station 100 receives a response signal including whether or not an error has occurred with respect to information from a plurality of ships 5 located in a predetermined area. In addition, when receiving the response signal, the base station 100 receives one or more of the average value of the radio wave intensity of the response signal from each of the plurality of vessels 5 and the error occurrence rate for the information. Calculate the value. In addition, the base station 100 determines that the information is the first transmission condition when the average value of the radio field intensity is lower than a predetermined reference and when the error rate is one or more among the cases where the error occurrence rate is high. Control to transmit under different second transmission conditions. As a result, information can be transmitted with high accuracy.

  In the base station 100, the second transmission condition is a lower baud rate than the first transmission condition. As a result, it is possible to transmit information with high accuracy while suppressing fluctuations in communication quality.

  Further, the base station 100 transmits one or more of the average value of the magnitude of the radio wave intensity calculated when the information is transmitted under the second transmission condition and the response signal is received, and the error occurrence rate for the information. When the average value of the radio field intensity is higher than the predetermined standard and when the error occurrence rate is one or more, the first transmission condition is set at the next transmission of information. Control to transmit with. As a result, when the radio wave propagation situation is improved, information can be transmitted with high accuracy using a higher modulation rate.

  In the above embodiment, a certain base station 100 transmits a broadcast message and receives an Ack message from the ship 5, but the present invention is not limited to this. For example, when another broadcast telegram is transmitted from another base station 100 to the ship 5 and the Ack telegram received by the other base station 100 indicates no error, the base station 100 transmits to the ship 5 The broadcast telegram to be transferred is transferred to another base station 100 via a network (not shown). The other base station 100 transmits the transferred broadcast message to the ship 5. Thereby, it is possible to transmit information with higher accuracy to the ship 5 that wants to transmit information.

  Moreover, in the said Example, although the message | telegram with a parity was used as a broadcast message | telegram, it is not limited to this. For example, using a double message, the communication terminal 10 transmits the appearance number, number, etc. of different character parts of two identical messages with an Ack message, and the base station 100 retransmits the different character parts. You may do it.

  In the above embodiment, the initial value of the transmission condition is set with reference to the default use flag and the previous use flag. However, the present invention is not limited to this. For example, you may make it change according to the timetable and broadcast content of the broadcast of the base station 100. As a result, for example, information that is to be transmitted with high accuracy can be transmitted at a low transmission speed from the first transmission but under strong transmission conditions, thereby increasing the accuracy with which the information can be transmitted to the ship 5, thereby suppressing rebroadcasting. be able to.

  Moreover, in the said Example, although the antenna connected to the communication part 110 of the base station 100 was each connected for every radio | wireless machine, it is not limited to this. For example, a multi-band antenna or an antenna tuner may be used. Further, different frequencies may be used for transmission from the ship to the land and transmission from the land to the ship. Thereby, the conditions of the antenna installation location are eased.

  Moreover, in the said Example, although PSK31 was mentioned as an example of digital modulation, it is not limited to this. For example, narrowband digital modulation that can be used in a short wave band such as RTTY (Radioteletype), packet communication, and SSTV may be used. Accordingly, communication with a larger amount of data can be performed in a high frequency band in the short wave band.

  Moreover, in the said Example, although the communication terminal 10 was installed in the ship 5, it is not limited to this. For example, the communication terminal 10 may be installed in a vehicle or the like in a communication difficult area such as a desert, a mountainous area, or a poorly populated area.

  In addition, each component of each part illustrated does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each unit is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed / integrated in arbitrary units according to various loads or usage conditions. Can be configured. For example, in the above-described embodiment, the communication control unit 131 executes the processing of the management information, the broadcast message, and the Ack message. However, the management information control unit that processes the management information, the broadcast message, and the Ack message. It may be divided into a broadcast control unit for processing. In addition, the illustrated processes are not limited to the above-described order, and may be performed at the same time as long as the process contents are not contradictory, or may be performed in a different order.

  Furthermore, various processing functions performed by each device may be executed entirely or arbitrarily on a CPU (or a microcomputer such as an MPU or MCU (Micro Controller Unit)). In addition, various processing functions may be executed in whole or in any part on a program that is analyzed and executed by a CPU (or a microcomputer such as an MPU or MCU) or on hardware based on wired logic. Needless to say, it is good.

  By the way, the various processes described in the above embodiments can be realized by executing a program prepared in advance by a computer. Therefore, in the following, an example of a computer that executes a program having the same function as in the above embodiment will be described. FIG. 8 is a diagram illustrating an example of a computer that executes a wireless communication program.

  As illustrated in FIG. 8, the computer 200 includes a CPU 201 that executes various arithmetic processes, an input device 202 that receives data input, and a monitor 203. The computer 200 also includes a medium reading device 204 that reads a program and the like from a storage medium, an interface device 205 for connecting to various devices, and a communication device 206 for connecting to other information processing devices and the like by wire or wirelessly. Have The computer 200 also includes a RAM 207 that temporarily stores various types of information and a hard disk device 208. Each device 201 to 208 is connected to a bus 209.

  The hard disk device 208 stores a wireless communication program having the same functions as the processing units of the communication control unit 131 and the calculation unit 132 shown in FIG. The hard disk device 208 also stores an area information storage unit 121, a transmission condition storage unit 122, a reception status storage unit 123, and various data for realizing a wireless communication program. The input device 202 receives input of various information such as operation information from an administrator of the computer 200, for example. The monitor 203 displays various screens for the administrator of the computer 200, for example. The interface device 205 is connected to, for example, a printing device. The communication device 206 has, for example, the same function as the communication unit 110 illustrated in FIG. 1 and is connected to the communication terminal 10 via the ionosphere L to exchange various information with the communication terminal 10 and to a network (not shown). Various information is exchanged with other connected base stations 100 and a server (not shown).

  The CPU 201 reads out each program stored in the hard disk device 208, develops it in the RAM 207, and executes it to perform various processes. In addition, these programs can cause the computer 200 to function as the communication control unit 131 and the calculation unit 132 illustrated in FIG. 1.

  Note that the above-described wireless communication program is not necessarily stored in the hard disk device 208. For example, the computer 200 may read and execute a program stored in a storage medium readable by the computer 200. The storage medium readable by the computer 200 corresponds to, for example, a portable recording medium such as a CD-ROM, a DVD disk, a USB (Universal Serial Bus) memory, a semiconductor memory such as a flash memory, a hard disk drive, and the like. Alternatively, the wireless communication program may be stored in a device connected to a public line, the Internet, a LAN, or the like, and the computer 200 may read and execute the wireless communication program from these devices.

  As described above, the following supplementary notes are further disclosed regarding the embodiment including the present example.

(Supplementary note 1) Information on ships located in a predetermined area is transmitted under the first transmission condition,
When receiving a response signal including whether or not an error has occurred with respect to the information from a plurality of ships located in the predetermined area, an average value of the magnitude of the radio wave intensity of the response signal from each of the plurality of ships, and Calculating one or more values of the error rate for the information;
The information is different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined standard and when the error occurrence rate is one or more. A wireless communication program that causes a computer to execute a process of performing transmission under the transmission conditions.

(Supplementary note 2) The wireless communication program according to supplementary note 1, wherein the second transmission condition is a baud rate lower than that of the first transmission condition.

(Additional remark 3) The process which performs the said control is about the average value of the magnitude | size of the said electromagnetic wave intensity calculated when the said information was transmitted on said 2nd transmission conditions, and the said response signal was received, and the said information For one or more values of the error occurrence rate, the average value of the radio field intensity is higher than the predetermined reference, and when the error occurrence rate is one or more The wireless communication program according to appendix 1 or 2, wherein transmission control is performed under the first transmission condition at the next transmission of information.

(Supplementary Note 4) Information on communication terminals located in a predetermined area is transmitted under the first transmission condition.
When receiving a response signal including whether or not an error has occurred with respect to the information from a plurality of communication terminals located in the predetermined area, an average of the magnitudes of the radio signal strengths of the response signals from the communication terminals of the plurality of communication terminals Calculating one or more values and an error rate for the information,
The information is different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined standard and when the error occurrence rate is one or more. A wireless communication program that causes a computer to execute a process of performing transmission under the transmission conditions.

(Supplementary Note 5) Information on ships located within a predetermined area is transmitted under the first transmission condition,
When receiving a response signal including whether or not an error has occurred with respect to the information from a plurality of ships located in the predetermined area, an average value of the magnitude of the radio wave intensity of the response signal from each of the plurality of ships, and Calculating one or more values of the error rate for the information,
The information is different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined standard and when the error occurrence rate is one or more. A wireless communication method, characterized in that a computer executes a process of performing transmission under the transmission conditions.

(Supplementary note 6) The wireless communication method according to supplementary note 5, wherein the second transmission condition is a lower baud rate than the first transmission condition.

(Additional remark 7) The process which performs the said control is about the said average value of the magnitude | size of the said electromagnetic field intensity calculated when the said information was transmitted on said 2nd transmission conditions, and the said response signal was received, and the said information For one or more values of the error occurrence rate, the average value of the radio field intensity is higher than the predetermined reference, and when the error occurrence rate is one or more The wireless communication method according to appendix 5 or 6, wherein transmission is performed under the first transmission condition at the next transmission of information.

(Supplementary note 8) Information on communication terminals located in a predetermined area is transmitted under the first transmission condition.
When receiving a response signal including whether or not an error has occurred with respect to the information from a plurality of communication terminals located in the predetermined area, an average of the magnitudes of the radio signal strengths of the response signals from the communication terminals of the plurality of communication terminals Calculating one or more values and an error rate for the information,
The information is different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined standard and when the error occurrence rate is one or more. A wireless communication method, characterized in that a computer executes a process of performing transmission under the transmission conditions.

(Supplementary Note 9) Information on a ship located in a predetermined area is transmitted under a first transmission condition, and a response signal including presence / absence of occurrence of an error with respect to the information is received from a plurality of ships located in the predetermined area Then, the average value of the magnitude of the radio wave intensity of the response signal from each of the plurality of ships, and a calculation unit that calculates one or more values of the error occurrence rate for the information,
One of the average value of the intensity of the radio wave intensity calculated by the calculation unit and the error rate is transmitted with the information on the ship located in the predetermined area under the first transmission condition. For the above values, when the average value of the radio field intensity is lower than a predetermined reference and when the error rate is high, the information is transmitted to the first transmission condition. A communication control unit that performs control for transmission under a second transmission condition different from
A radio base station characterized by comprising:

(Supplementary note 10) The radio base station according to supplementary note 9, wherein the second transmission condition is a lower baud rate than the first transmission condition.

(Additional remark 11) The said communication control part is an average value of the magnitude | size of the said electromagnetic field intensity calculated when transmitting the said information on said 2nd transmission conditions, and receiving the said response signal, and about the said information For one or more values of the error rate, if the average value of the radio field intensity is higher than the predetermined standard, and if the error rate is one or more of the cases where the error rate is low, The radio base station according to appendix 9 or 10, wherein transmission is performed under the first transmission condition at the next transmission of information.

(Additional remark 12) The information with respect to the communication terminal located in a predetermined area is transmitted on 1st transmission conditions, and the response signal containing the presence or absence of the error generation with respect to the said information from the some communication terminal located in the said predetermined area , A calculating unit that calculates one or more values of the average value of the radio field intensity of the response signal from each communication terminal of the plurality of communication terminals and the error occurrence rate for the information; ,
The information for the communication terminal located in the predetermined area is transmitted under the first transmission condition, and one of the average value of the radio field intensity calculated by the calculation unit and the error occurrence rate is 1 For one or more values, the information is transmitted in the first transmission when an average value of the radio field intensity is lower than a predetermined reference and when the error occurrence rate is one or more. A communication control unit that performs control to transmit under a second transmission condition different from the condition;
A radio base station characterized by comprising:

(Supplementary note 13) A wireless communication system having a ship and a wireless base station,
The ship is
When receiving information from the radio base station, it has a communication terminal that transmits a response signal including the presence or absence of error occurrence for the information,
The radio base station is
When information on a ship located in a predetermined area is transmitted under a first transmission condition and a response signal including presence / absence of error occurrence with respect to the information is received from a plurality of ships located in the predetermined area, the plurality of An average value of the magnitude of the radio wave intensity of the response signal from each of the ships, and a calculation unit that calculates one or more values of the error occurrence rate for the information,
One of the average value of the intensity of the radio wave intensity calculated by the calculation unit and the error rate is transmitted with the information on the ship located in the predetermined area under the first transmission condition. For the above values, when the average value of the radio field intensity is lower than a predetermined reference and when the error rate is high, the information is transmitted to the first transmission condition. A communication control unit that performs control for transmission under a second transmission condition different from
A wireless communication system comprising:

(Supplementary note 14) The wireless communication system according to supplementary note 13, wherein the second transmission condition is a lower baud rate than the first transmission condition.

(Supplementary Note 15) The communication control unit transmits an average value of the radio field intensity calculated when the information is transmitted under the second transmission condition and the response signal is received, and the information For one or more values of the error rate, if the average value of the radio field intensity is higher than the predetermined standard, and if the error rate is one or more of the cases where the error rate is low, 15. The wireless communication system according to appendix 13 or 14, wherein transmission is performed under the first transmission condition when next information is transmitted.

(Supplementary Note 16) A wireless communication system having a communication terminal and a wireless base station,
The communication terminal is
Upon receiving information from the radio base station, a response signal including the presence or absence of an error occurrence for the information is transmitted,
The radio base station is
When information on a communication terminal located in a predetermined area is transmitted under a first transmission condition, and a response signal including presence / absence of occurrence of an error with respect to the information is received from a plurality of communication terminals located in the predetermined area, An average value of the magnitude of the radio wave intensity of the response signal from each communication terminal of the plurality of communication terminals, and a calculation unit that calculates one or more values of the error occurrence rate for the information;
The information for the communication terminal located in the predetermined area is transmitted under the first transmission condition, and one of the average value of the radio field intensity calculated by the calculation unit and the error occurrence rate is 1 For one or more values, the information is transmitted in the first transmission when an average value of the radio field intensity is lower than a predetermined reference and when the error occurrence rate is one or more. A communication control unit that performs control to transmit under a second transmission condition different from the condition;
A wireless communication system comprising:

DESCRIPTION OF SYMBOLS 1 Wireless communication system 5 Ship 10 Communication terminal 11 Communication part 12 Storage part 13 Positioning part 14 Display operation part 15 Control part 100 Base station 110 Communication part 120 Storage part 121 Area information storage part 122 Transmission condition storage part 123 Reception condition storage part 130 Control unit 131 Communication control unit 132 Calculation unit L Ionosphere

Claims (7)

Send information for ships located in a given area under the first transmission condition,
When receiving a response signal including whether or not an error has occurred with respect to the information from a plurality of ships located in the predetermined area, an average value of the magnitude of the radio wave intensity of the response signal from each of the plurality of ships, and Calculating one or more values of the error rate for the information;
The information is different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined standard and when the error occurrence rate is one or more. A wireless communication program that causes a computer to execute a process of performing transmission under the transmission conditions.   The wireless communication program according to claim 1, wherein the second transmission condition is a lower baud rate than the first transmission condition.   The process of performing the control includes an average value of the magnitude of the radio wave intensity calculated when the information is transmitted under the second transmission condition and the response signal is received, and an error occurrence rate for the information If the average value of the radio field intensity is higher than the predetermined reference and one or more values are low, the next information The wireless communication program according to claim 1, wherein transmission is performed under the first transmission condition at the time of transmission. Send information for communication terminals located in a given area under the first transmission condition,
When receiving a response signal including whether or not an error has occurred with respect to the information from a plurality of communication terminals located in the predetermined area, an average of the magnitudes of the radio signal strengths of the response signals from the communication terminals of the plurality of communication terminals Calculating one or more values and an error rate for the information,
The information is different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined standard and when the error occurrence rate is one or more. A wireless communication program that causes a computer to execute a process of performing transmission under the transmission conditions. Send information for ships located in a given area under the first transmission condition,
When receiving a response signal including whether or not an error has occurred with respect to the information from a plurality of ships located in the predetermined area, an average value of the magnitude of the radio wave intensity of the response signal from each of the plurality of ships, and Calculating one or more values of the error rate for the information;
The information is different from the first transmission condition when the average value of the radio field intensity is lower than a predetermined standard and when the error occurrence rate is one or more. A wireless communication method, characterized in that a computer executes a process of performing transmission under the transmission conditions. When information on a ship located in a predetermined area is transmitted under a first transmission condition and a response signal including presence / absence of error occurrence with respect to the information is received from a plurality of ships located in the predetermined area, the plurality of An average value of the magnitude of the radio wave intensity of the response signal from each of the ships, and a calculation unit that calculates one or more values of the error occurrence rate for the information,
One of the average value of the intensity of the radio wave intensity calculated by the calculation unit and the error rate is transmitted with the information on the ship located in the predetermined area under the first transmission condition. For the above values, when the average value of the radio field intensity is lower than a predetermined reference and when the error rate is high, the information is transmitted to the first transmission condition. A communication control unit that performs control for transmission under a second transmission condition different from
A radio base station characterized by comprising: A wireless communication system having a ship and a wireless base station,
The ship is
When receiving information from the radio base station, it has a communication terminal that transmits a response signal including the presence or absence of error occurrence for the information,
The radio base station is
When information on a ship located in a predetermined area is transmitted under a first transmission condition and a response signal including presence / absence of error occurrence with respect to the information is received from a plurality of ships located in the predetermined area, the plurality of An average value of the magnitude of the radio wave intensity of the response signal from each of the ships, and a calculation unit that calculates one or more values of the error occurrence rate for the information,
One of the average value of the intensity of the radio wave intensity calculated by the calculation unit and the error rate is transmitted with the information on the ship located in the predetermined area under the first transmission condition. For the above values, when the average value of the radio field intensity is lower than a predetermined reference and when the error rate is high, the information is transmitted to the first transmission condition. A communication control unit that performs control for transmission under a second transmission condition different from
A wireless communication system comprising:

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