JP2001016212A - Orbcomm communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Orbcomm communication system by which multiple transmission/multiple reception can be avoided. SOLUTION: The Orbcomm communication system consists of a satellite, of an Orbcomm mobile communication terminal having a satellite transmission reception circuit 7 that makes transmission reception with the satellite and a central arithmetic unit 1 that controls transmission reception processing, and of a base station that is connected to a ground general communication channel and makes communication with the Orbcomm mobile communication terminal via the satellite. The satellite conducts increase/decrease control of the number of transmission times of a Final Ack that is a reception end notice of an incoming message in the case of making data communication using a protocol with the Orbcomm mobile communication terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station connected to a general terrestrial communication line (terrestrial communication network), a satellite linked to the base station, and Obcom performing wireless data communication with the base station via the satellite. The present invention relates to an Orbcom communication system including a mobile communication terminal.

[0002]

2. Description of the Related Art In recent years, global orbcom mobile communication terminals using low-orbit satellites have come into practical use.

[0003] Hereinafter, an Orbcom communication system having a conventional Orbcom mobile communication terminal will be described with reference to the drawings.

FIG. 1 is a block diagram showing a general Orbcom mobile communication terminal.

In FIG. 1, 1 is a central processing unit for controlling transmission / reception processing, 2 is a program storage unit for recording a program that defines the operation of the central processing unit 1, and 3 is a rewritable memory for recording a flag or the like during processing. 4, a transmission message storage memory for storing the created uplink transmission message; 5, a reception message storage memory for storing the received downlink reception message; 6, an antenna for transmitting and receiving communication radio waves to and from the satellite; This is a wireless transmitting / receiving circuit as a satellite transmitting / receiving circuit for performing wireless communication.

The operation of a conventional orbcom communication system having an orbcom mobile communication terminal configured as described above will be described with reference to FIGS. FIG.
6 is a sequence diagram of a normal uplink message transmission,
FIG. 17 is a sequence diagram of normal downlink message reception, FIG. 18 is a sequence diagram of double transmission in uplink communication, and FIG. 19 is a sequence diagram of double reception in downlink communication.

[0007] The message transmission process of the Orbcom mobile communication terminal is performed in the following procedure.

First, a transmission message is created internally by an event occurrence or a user command. A destination is added to this outgoing message.
It is possible to specify an e-mail address or a speed dial registered in the base station. Upon capturing radio waves from the satellite, the Orbcom mobile communication terminal transmits a burst signal before transmitting a message to the satellite, and confirms that communication is possible. When transmission is confirmed, the message is divided into packets according to the protocol and transmitted.

A transmission procedure in accordance with this protocol is shown in FIG.
Shown in After sending the last packet,
The transmission of the message is completed when the nal ACK (reception completion notification) is received. The satellite transfers the message to the base station upon receiving the final packet. The base station receiving the message from the satellite transfers the message to the HOST (recipient) on the terrestrial communication system according to the destination specified in the message. The Orbcom mobile communication terminal receives the Final ACK from the satellite after the transmission is completed, and determines that the transmission has been completed.
If it cannot receive ACK, it transmits ENQ (inquiry) and waits for Final ACK again. But again Final
If ACK cannot be received, retry is performed a specified number of times, and then the process proceeds to the next message transmission process as a communication failure.

The message receiving process of the Orbcom mobile communication terminal is performed in the following procedure. This receiving procedure is shown in FIG.

A message sent from a caller (HOST) on a terrestrial communication network to an Orbcom mobile communication terminal is sent from a base station to a satellite. The Orbcom mobile communication terminal, which has received the radio wave from the satellite and confirmed that there is a downlink message addressed to itself, starts receiving the downlink message. Downlink messages divided into packets are transmitted from the satellite in accordance with the protocol, and received to assemble the messages. After receiving the last packet,
After returning Final ACK to the satellite, EN from the satellite
After waiting for Q (inquiry) for a certain period of time, the protocol is terminated. If ENQ is received during this standby, the satellite
This means that the internal ACK could not be received, and the final ACK is transmitted again.

[0012]

However, the above-mentioned conventional Orbcom communication system has the following problems.

At the time of transmitting an uplink message, the satellite transmits the transmitted Final ACK to the base station without confirming whether or not the Orbcom mobile communication terminal has received the final ACK. On the other hand, Orbcom mobile communication terminals
If the ACK cannot be received and the ENQ (inquiry) is not received by the satellite, it is determined that the transmission of the uplink message has failed, and the transmission is performed again, resulting in the double transmission of the same message. FIG. 18 shows a flow in which this double transmission occurs.

[0014] Further, at the time of receiving a downlink message, the Orbcom mobile communication terminal terminates the reception protocol without confirming whether the transmitted Final ACK has been received by the satellite and ends the reception of the message. On the other hand, the satellite cannot receive Final ACK and ENQ
If the (inquiry) is not received by the Orbcom mobile communication terminal, it is determined that the transmission of the downlink message has failed, and the transmission is performed again, thereby causing the double reception of the same message. FIG. 19 shows a flow in which this double reception occurs.

If the above-mentioned process occurs continuously a plurality of times, multiplex transmission / multiplex reception such as triple transmission / triple reception, quadruple transmission / quadruple reception occurs.

In the Orbcom communication system, it is required to avoid multiplex transmission and multiplex reception.

An object of the present invention is to provide an Orbcom communication system capable of avoiding multiplex transmission and multiplex reception.

[0018]

To solve the above problems, an orbcom communication system according to the present invention comprises an orbcom mobile communication system having a satellite, a satellite transmitting / receiving circuit for transmitting / receiving to / from the satellite, and a central processing unit for controlling the transmitting / receiving process. An orbcom communication system comprising a communication terminal and a base station connected to a general communication line on the ground and communicating with the orbcom mobile communication terminal via a satellite, wherein the satellite is connected to the orbcom mobile communication terminal. When data communication is performed using a protocol between devices, F is a reception completion notification for an uplink message.
A configuration for increasing / decreasing the number of times of transmission of the internal ACK is provided.

As a result, an Orbcom communication system capable of avoiding multiplex transmission and multiplex reception can be obtained.

[0020]

DETAILED DESCRIPTION OF THE INVENTION An orbcom communication system according to a first aspect of the present invention is an orbcom mobile communication terminal having a satellite, a satellite transmission and reception circuit for transmitting and receiving to the satellite, and a central processing unit for controlling transmission and reception processing. A base station connected to a general communication line on the ground and communicating with the Orbcom mobile communication terminal via a satellite, wherein the satellite has a protocol with the Orbcom mobile communication terminal. ACK, which is a reception completion notification for an uplink message when performing data communication using
The number of times of transmission is controlled to increase or decrease.

[0021] With this configuration, the number of times of reception completion detection in the Orbcom mobile communication terminal can be increased as necessary, so that the same data can be prevented from being retransmitted.

An orbcom communication system according to a second aspect is connected to an orbcom mobile communication terminal having a satellite, a satellite transmission and reception circuit for transmitting and receiving to the satellite, and a central processing unit for controlling the whole, and a general communication line on the ground. And a base station that communicates with the Orbcom mobile communication terminal via a satellite, wherein the central processing unit transmits the F.
This is to control the increase / decrease of the number of times of transmission of the internal ACK.

With this configuration, the number of reception completion detections on the satellite side can be increased, so that the same data can be prevented from being re-received.

According to a third aspect of the present invention, in the orbcom communication system according to the first aspect, the satellite controls the number of times of transmitting Final ACK to increase or decrease according to the state of the communication line. is there.

With this configuration, the number of reception completion detections at the Orbcom mobile communication terminal is reduced when the communication line condition is good, and the reception completion at the Orbcom mobile communication terminal is reduced when the communication line condition is bad. This has the effect that the number of times of detection can be increased.

According to a fourth aspect of the present invention, in the orbcom communication system according to the second aspect, the central processing unit controls the number of times of transmitting Final ACK to increase or decrease according to the state of the communication line. Things.

With this configuration, the number of reception completion detections on the satellite side is reduced when the state of the communication line is good, and the number of reception completion detections on the satellite side is reduced when the state of the communication line is bad. It has the effect of being able to increase.

According to a fifth aspect of the present invention, in the orbcom communication system according to the first or third aspect, when a plurality of final ACKs are transmitted, the satellite communicates a time interval for transmitting a plurality of final ACKs. The increase / decrease control is performed according to the state of the line.

According to this configuration, the transmission time interval is shortened when the communication line is good, and the transmission time interval is shortened when the communication line is bad, so that the possibility of detecting the completion of reception at the Orbcom mobile communication terminal is improved. It has the effect of being able to increase.

The orbcom communication system according to claim 6 is the orbcom communication system according to claim 2 or 4, wherein the central processing unit transmits the final ACK.
In the case where there are a plurality of ACKs, the time interval for transmitting a plurality of Final ACKs is controlled to increase or decrease according to the state of the communication line.

With this configuration, when the communication line is good, the transmission time interval is shortened, and when the communication line is bad, the transmission time interval is shortened, and the possibility of detecting the completion of reception by the satellite is improved. Has the effect of being able to.

[0032] In the Orbcom communication system according to the seventh aspect, in the Orbcom communication system according to the first, third or fifth aspect, the central processing unit performs transmission by assigning a unique management number to each uplink message, After the transmission protocol is completed, the satellite is inquired of the transmission completion using the management number, and if the transmission is completed, the transmission completion message in the transmission queue is deleted. If the transmission is not completed, the transmission is performed again. Things.

This configuration has the effect of preventing retransmission of the same data when transmission is completed.

According to an eighth aspect of the present invention, in the orbcom communication system according to the second, fourth or sixth aspect, the base station assigns a unique management number to each downlink message via a satellite and transmits the downlink message. The transmission completion or non-transmission completion from the Orbcom mobile communication terminal in response to the inquiry about the transmission completion of the transmission message using the management number performed by the satellite after the completion of the transmission protocol is received, and the transmission completion message is deleted or transmitted to the satellite. The incomplete message is requested to be transmitted again.

This configuration has the effect of preventing retransmission of the same data when transmission is completed.

[0036] In the Orbcom communication system according to the ninth aspect, in the Orbcom communication system according to the second, fourth, sixth or eighth aspect, the central processing unit simultaneously receives the unique management number assigned to each downlink message. A message is stored, a response is made to a received / unreceived inquiry using a management number from a satellite, and if the same message is transmitted, it is notified that the message has been received. is there.

This configuration has the effect of preventing the same data from being re-received when it has been received.

According to a tenth aspect of the present invention, in the orbcom communication system according to the first, third, fifth, or seventh aspect, the central processing unit assigns a unique management number to each uplink message and performs transmission. After the transmission protocol is completed, when inquiring of the transmission completion of the transmission message to the satellite using the management number after the completion of the transmission protocol, the transmission completion inquiry is not completed when the communication condition is bad or the satellite is about to sink. This is performed only for the transmitted message.

According to this configuration, the transmission completion inquiry is made only for the transmission message for which the protocol has not been completed, so that the inquiry can be efficiently performed.

According to an eleventh aspect of the present invention, there is provided the orbcom communication system according to the first, third, fifth, seventh, or tenth aspect, wherein the central processing unit has a non-volatile memory such as a backup memory. The fact that the transmission result of the message is being checked is stored in the non-volatile memory together with the management number unique to the upstream message, and even if the power of the Orbcom mobile communication terminal is turned off before the transmission process is completed, the next power In this case, the transmission result of the transmission message stored in the non-volatile memory is checked again when is inserted.

This configuration has the effect of preventing double transmission even if the power is interrupted during communication.

According to a twelfth aspect of the present invention, there is provided the orbcom communication system according to the second, fourth, sixth, eighth or ninth aspect, wherein the central processing unit has a non-volatile memory such as a backup memory. Even if the communication is interrupted by turning off the power of the Orbcom mobile communication terminal before the transmission processing on the satellite side is completed, the downlink message together with the unique management number is stored in the non-volatile memory,
The next time communication is resumed, it is determined whether the message is the same by comparing the unique number of the downlink message stored in the nonvolatile memory with the unique number included in the downlink message from the satellite. Things.

This configuration has the effect that double reception is prevented even when the power supply is interrupted during communication.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) The configuration of an Orbcom mobile communication terminal constituting an Orbcom communication system according to Embodiment 1 of the present invention is the same as the conventional one shown in FIG. This embodiment differs from the conventional Orbcom mobile communication terminal in the communication procedure and the like.

The operation of the orbcom communication system having the orbcom mobile communication terminal configured as described above will be described with reference to FIGS. FIG. 2 shows F
FIG. 3 is a sequence diagram in which internal ACK is increased.
Is a graph showing the number of Final ACK transmissions according to the communication state (line state) in the Orbcom mobile communication terminal, FIG. 4 is a sequence diagram in which Final ACK is increased during reception, and FIG. 5 is Final ACK according to the communication state.
FIG. 6 is a graph showing transmission intervals of the data.

The message transmission process of the Orbcom mobile communication terminal is performed in the following procedure.

First, a transmission message is created internally by the occurrence of an event or a user command. A destination is added to this outgoing message.
It is possible to specify an e-mail address or a speed dial registered in the base station. When the Orbcom mobile communication terminal transmits a newly created message, the following processing is performed.

First, a request packet for requesting the satellite to transmit a message is transmitted. When a response is returned, the upstream message is divided into packets and transmitted according to the protocol. After transmitting the final packet, it waits for Final ACK (reception completion notification) from the satellite. If it cannot be received within a certain period of time due to bad line conditions or the like, ENQ (inquiry)
Perform The satellite transmits a plurality of Final ACKs at time intervals as shown in FIG. 2 in order to prevent such a final ACK from being missed on the mobile terminal side. Orbcom mobile communication terminal sends Fi
nal ACK is processed for the same message. The number of transmissions of this Final ACK is changed according to the line state.

The packet error rate is used as an index indicating the line state, and the number of transmissions of Final ACK is controlled according to the error rate as shown in FIG. When the line condition is good such as when the error rate is less than 5%, the number of transmissions is reduced, and when the line condition is bad, the number of transmissions is increased.

The message receiving process of the Orbcom mobile communication terminal is performed in the following procedure.

A message sent from a caller (HOST) on the terrestrial communication network to the Orbcom mobile communication terminal is sent from the base station to the satellite. Orbcom mobile communication terminals
It receives radio waves from the satellite, confirms that there is a downlink message addressed to itself, and starts receiving downlink messages. Downlink messages divided into packets are transmitted from the satellite in accordance with the protocol, and received to assemble the messages. After receiving the final packet, a plurality of Final ACKs are transmitted at time intervals as shown in FIG. 4 in order to prevent Final ACK reception omission of the satellite. The number of transmissions of this Final ACK is changed according to the line state. The packet error rate is used as an index indicating the line state, and the number of final ACK transmissions is controlled according to the error rate as shown in FIG. When the line condition is good such as when the error rate is less than 5%, the number of transmissions is reduced, and when the line condition is bad, the number of transmissions is increased.

As described above, according to the present embodiment, Fi
The probability of successful transmission / reception of nal ACK is increased, and double transmission and double reception can be reduced.

(Embodiment 2) The configuration of an orbcom mobile communication terminal constituting an orbcom communication system according to a second embodiment of the present invention is the same as that of the first embodiment shown in FIG. This embodiment is different from the first embodiment in the communication procedure and the like.

The operation of the orbcom communication system having the orbcom mobile communication terminal configured as described above will be described with reference to FIGS. 6 and 7 are communication procedure diagrams showing a transmission communication procedure according to the second embodiment of the present invention, FIG. 8 is a flowchart showing a transmission process according to the second embodiment of the present invention, and FIG. FIG. 10 is a management data diagram showing internal management of a transmission message.

In FIG. 7, reference numeral 8 denotes a transmission queue in the transmission message storage memory 4 accessed from the central processing unit 1 of the Orbcom mobile communication terminal, 9 denotes an initial state of an uplink message reception and recording memory inside the base station, 10 Is a state in which a message has been received in the uplink message reception and recording memory inside the base station.

The operation of the orbcom communication system having the orbcom mobile communication terminal configured as described above will be described.

First, the message 1 is set to Message Se.
Queue Number = 1 (MSN1), and transmission is performed according to the protocol. After transmitting the final packet, the terminal waits for a final ACK for a predetermined time. However, if the link condition is bad and the uplink message is not sent correctly, the satellite returns NACK (Non ACK).
Also when the Orbcom mobile communication terminal cannot receive the signal, the Orbcom communication terminal transmits the ENQ a plurality of times, but does not reach as shown in FIG. After that, the protocol ends due to a timeout. The above flow is shown as process 1 in FIG.

Since the Orbcom mobile communication terminal has transmitted up to the final packet, it is in a state of only receiving Final ACK and need only confirm the transmission result. Accordingly, the Orbcom mobile communication terminal does not delete the message but attaches a flag indicating that the transmission result is unconfirmed and holds the message. Next, when communicating with the satellite, the result of the message whose transmission result has not been confirmed last time is inquired using ASK (MSN1) (FIG. 7). As a result, since the satellite side has not received normally, NO (MSN1) is returned. Therefore, the Orbcom mobile communication terminal transmits the message 1 again from the beginning. This transmission protocol correctly transmits the last packet to the satellite, but then transmits ENQ when Final ACK from the satellite has not arrived due to deterioration of the line condition. However, ENQ is not received, and Final ACK is transmitted to Obcom mobile communication. The terminal cannot receive and terminates the protocol due to timeout. Since the satellite can receive the final packet and has transmitted the Final ACK, the satellite transmits the message to the base station and records it in the uplink message reception recording memory. Then, the base station transmits to the HOST. The above flow is shown in process 2 of FIG.

Next, when communication with the satellite is possible, first, as in process 2, an inquiry about the result of the previous transmission message is made by AS.
Performed as K (MSN1). The satellite searches the uplink message reception record memory and replies YES (MSN1) because the message of MSN1 has already been received. The Orbcom mobile communication terminal that has received this answer deletes the message 1 from the transmission queue 8 as completion of transmission. Then, transmission is started with the next transmission message 2 as MSN2. The final packet of message 2 is successfully transmitted, a Final ACK from the satellite is transmitted, and the process ends. The above flow is shown as process 3 in FIG.

FIG. 8 shows a flow of transmitting a message to a satellite. In FIG. 8, a signal from a satellite is searched (S1,
S2) When communication is established, message transmission is started.
At this time, a transmission message is selected from the transmission queue 8 in consideration of the priority (S3). If there is no message whose transmission result has not been confirmed (S4), the message is transmitted according to the protocol (S5), and after transmitting the final packet, it waits for a Final ACK from the satellite (S4).
6). If Final ACK is not received after waiting for a certain period of time, an ENQ is sent to request retransmission (S7, S7).
8). If Final ACK is not sent after waiting for a certain period of time again, ENQ is sent until Final ACK is reached until retry over occurs. Final ACK
Is received, the message is determined to have been successfully transmitted, and the message is deleted from the transmission queue 8 (S9). If the retry is over and the Final ACK cannot be received, the message is flagged as unconfirmed and the message is stored in the transmission queue 8 (S10). Then, a signal from the satellite is searched again, and if communication is successful, the transmission process is started again. At this time, the Orbcom mobile communication terminal uses the transmission queue 8
Consider the priority of the messages inside. If there is an unsent message with a high priority, the sending process is performed first. If there is no unsent message with a high priority and there is a message whose transmission result has not been confirmed, the message transmission result is first confirmed (S11). MSN is used as a method for specifying a message when confirming the transmission result of the message. In response to the response (YES, NO) from the satellite linked with the base station by transmitting the ASK (MSN) (S12, S13), (1) deletion from transmission queue 8 (S14) or (2) retransmission ( Perform any one of S15). If a response is not sent after waiting for a certain period of time, an ENQ is sent and a response is waited until retry over occurs (S16).

[0062] Final A
If the CK has been successfully received, the terminal deletes the message from the transmission queue 8. Therefore, the transmission result confirmation of the message is performed only for the message in which the result is not confirmed together with the MSN in the transmission queue 8. That is,
Only when the terminal cannot receive the Final ACK due to the sinking of the satellite or the like, a transmission result inquiry is performed to communicate with the satellite next time.

FIG. 9 shows an example of the transmission information form of the transmission message.
Shown in It comprises an MSN for specifying a message, the number of destinations, a group of destination addresses, a message body, and a checksum for error detection. This MSN is uniquely assigned to each message, but has two bits in order to reduce transmission bits. With two bits, up to four messages can be distinguished by MSN, and unless there is a higher priority, the next message is not transmitted until the transmission result of the message of MSN1 is confirmed. It is sufficient if four MSNs can be provided.

FIG. 9 shows an example of the transmission order of messages in the transmission queue 8 and a method of assigning an MSN number. If there are three messages, the highest priority message 2
Is sent first. At that time, the MSN number is given 1. Since Final ACK is normally received and transmission is completed, and it is not necessary to confirm the transmission result again, the transmission result confirmation flag is not set. Thereafter, the message 2 is deleted from the transmission queue 8. Since the remaining two messages have the same priority, the previously registered message 1 is transmitted. At that time, MSN is incremented by 1 and transmitted as MSN2. Orbcom mobile communication terminal uses Fina from satellite
l Since the ACK could not be received, the transmission result confirmation flag is set. At the next transmission, messages 1 and 3 having the same priority remain, and the transmission result confirmation flag for the message 1 is set. Therefore, the transmission result of the message 1 is confirmed.

Between process 1 and 2 or process 2
Even if the power of the Orbcom mobile communication terminal is turned off between the steps 3 and 3, the information on the communication such as the MSN number is recorded in the non-volatile memory, so that the processing can be restarted when the power is turned on next time. it can.

As described above, according to the present embodiment, central processing unit 1 performs transmission by assigning a unique management number to each uplink message, and uses the management number for the satellite after completing the transmission protocol. An inquiry about the completion of transmission of the transmission message is made. If the transmission is completed, the transmission completion message in the transmission queue 8 is deleted, and if the transmission is not completed, the transmission is performed again. Transmission can be prevented.

The central processing unit 1 has a non-volatile memory such as a backup memory, and stores in the non-volatile memory that the transmission result of the transmission message is being checked together with a management number unique to the upstream message. Even if the power of the Orbcom mobile communication terminal is turned off before the processing is completed, the transmission result of the transmission message stored in the non-volatile memory is checked again when the power is turned on next time. In addition, double transmission can be prevented even when power is interrupted during communication.

(Embodiment 3) The configuration of an Orbcom mobile communication terminal according to Embodiment 3 of the present invention is as described in Embodiments 1 and 2.
The configuration is the same as that shown in FIG. This embodiment is different from the first and second embodiments in the communication procedure and the like.

FIG. 11 shows an orbcom communication system having an orbcom mobile communication terminal configured as described above.
This will be described with reference to FIGS. 11 and 12 are communication procedure diagrams showing a receiving communication procedure according to the third embodiment of the present invention. FIG. 13 is a flowchart showing a receiving process according to the third embodiment of the present invention. FIG. 15 is a management data diagram showing internal management of a received message.

In FIG. 12, reference numeral 11 denotes an initial state of a downlink message recording memory in the base station, 12 denotes a reception queue in the reception message storage memory 5 accessed by the central processing unit 1 of the Orbcom mobile communication terminal, and 13 denotes a base station. This is a state after a message has been transmitted to the downstream message recording memory inside the station.

In FIG. 11, first, message 1 is set to M
The satellite performs transmission according to the protocol SN1.
Satellite sends Final ACK after sending last packet
Wait for a certain time. However, when the line condition is bad and the downlink message cannot be received correctly, the Orbcom mobile communication terminal returns NACK (Non ACK).
If the satellite also fails to receive it, the satellite transmits ENQ multiple times, but does not reach as shown in FIG. Thereafter, both ends the protocol due to a timeout. The above flow is shown as process 1 in FIG.

Since the satellite has transmitted up to the last packet,
After that, it is in a state of only receiving Final ACK, and it is only necessary to confirm transmission success. Therefore, the base station linked to the satellite does not delete the message but keeps the flag with the transmission result unconfirmed. When the next communication is performed, the base station linked to the satellite inquires the result of the message whose transmission result has not been confirmed last time by using ASK (MSN1) (FIG. 12). Since the Orbcom mobile communication terminal has not received the inquiry normally, it returns NO (MSN
Return 1). Therefore, the base station linked to the satellite transmits message 1 again from the beginning. The Orbcom mobile communication terminal was able to correctly receive the last packet with this transmission protocol, but after that the final state due to the deterioration of the line condition
If the ACK does not reach the satellite, the satellite transmits an ENQ, but is not received by the Orbcom mobile communication terminal, and
The satellite cannot receive al ACK and terminates the protocol due to timeout. The Orbcom mobile communication terminal can receive the final packet, and the Final ACK
Is transmitted, and is recorded in the reception queue 12 together with the MSN 1. The above flow is shown as process 2 in FIG.

Next, when the satellite can communicate with the Orbcom mobile communication terminal, first, as in the process 2, the satellite inquires the result of the previous transmission message ASK (MSN1).
The Orbcom mobile communication terminal searches the message reception record memory and replies YES because the message of MSN1 has already been received (FIG. 12). The satellite receiving this response deletes the message 1 from the transmission queue as completion of transmission (see states 11 and 13). Then, transmission is started with the next transmission message 2 as MSN2. The transmission of the final packet of the message 2 is successful, and the Orbcom mobile communication terminal transmits a Final ACK, which is received by the satellite, and the process ends. The above flow is shown as process 3 in FIG.

FIG. 1 shows a flow of receiving a message from a satellite.
3 is shown. The Orbcom mobile communication terminal searches for a signal from a satellite (S21, S22), and if communication is possible and a message exists (S23), reception starts. At this time, if an inquiry is first made as to whether or not the message has already been received using the MSN (S24), the Orbcom mobile communication terminal compares the MSNs of the already received messages and checks whether they are the same (S25). If they are the same, the reception has been completed, so the reception status (YES) is returned to the satellite (S26). If the same MSN is not found in the record, the message is a non-received message, so a non-received status (NO) is returned and a normal reception protocol is started (S27). If normal reception was possible up to the last packet (S28), the Orbcom mobile communication terminal transmits Final ACK (S2).
9) The message is stored in the reception queue 12 together with the MSN (S30). If normal reception up to the last packet cannot be performed, a NACK is transmitted to the satellite (S
31) Return to step 21.

FIG. 1 shows an example of the transmission information format of the received message.
It is shown in FIG. It is composed of an MSN for specifying a message, a sender address, a message body, and a checksum for error detection. This MSN is uniquely assigned to each message, but has two bits to reduce transmission bits. MS with 2 bits up to 4 messages
N, and the next message is not transmitted until the transmission result of the message of MSN1 is confirmed unless there is a message with a higher priority.
It is sufficient if MSNs can be provided.

FIG. 15 shows an example of a method for storing a message in the reception queue 12. In the base station and the satellite, a transmission message is selected based on the priority, and an MSN is added and transmitted according to the order. Therefore, the Orbcom mobile communication terminals store the data in the order of reception.

Between processes 1 and 2 or process 2
Even if the power of the Orbcom mobile communication terminal is turned off between the steps 3 and 3, the information on the communication such as the MSN number is recorded in the non-volatile memory, so that the processing can be restarted when the power is turned on next time. it can.

As described above, according to the present embodiment, central processing unit 1 stores the received message at the same time as the unique management number assigned to each downlink message, and uses the management number from the satellite. By responding to the received / unreceived inquiry and notifying that it has been received when the same message is sent,
If the data has already been received, re-reception of the same data can be prevented.

Further, the central processing unit 1 has a non-volatile memory such as a backup memory, stores the received downlink message together with a unique management number in the non-volatile memory, and stores the received downlink message before the transmission processing on the satellite side is completed. Even if communication is interrupted due to the power off of the Orbcom mobile communication terminal, the unique number of the downlink message stored in the non-volatile memory is compared with the unique number included in the downlink message from the satellite when the communication is restarted next time By doing so, it is determined whether or not the messages are the same message, so that double reception can be prevented even when power is interrupted during communication.

[0080]

As described above, the orbcom communication system according to the first aspect of the present invention includes a satellite, a satellite transmission / reception circuit for transmitting / receiving to / from the satellite, and a central processing unit for controlling transmission / reception processing. Orbcom mobile communication terminal,
An orbcom communication system comprising a base station connected to a general communication line on the ground and communicating with the orbcom mobile communication terminal via a satellite, wherein the satellite communicates a protocol with the orbcom mobile communication terminal. When performing data communication by using this method, by increasing or decreasing the number of transmissions of Final ACK, which is a reception completion notification for an uplink message, the number of reception completion detections at the Orbcom mobile communication terminal can be increased as necessary. Therefore, the same data can be prevented from being retransmitted, and an advantageous effect that multiplex transmission in the Orbcom mobile communication terminal and multiplex reception in the satellite can be avoided can be obtained.

According to the Orbcom communication system of the present invention, an Orbcom mobile communication terminal having a satellite, a satellite transmitting / receiving circuit for transmitting and receiving to the satellite, and a central processing unit for controlling the whole, and a general terrestrial communication line And a base station that communicates with the Orbcom mobile communication terminal via a satellite, wherein the central processing unit transmits the Final ACK, which is a notification of completion of reception of the downlink message. By increasing or decreasing the number of times, it is possible to increase the number of reception completion detections on the satellite side, so that re-reception of the same data can be prevented, and multiplex reception in the Orbcom mobile communication terminal and multiplex transmission in the satellite can be avoided. This has the advantageous effect of being able to perform.

According to the Orbcom communication system according to the third aspect, in the Orbcom communication system according to the first aspect, the satellite controls the number of times of transmitting Final ACK to increase or decrease according to the state of the communication line. If the condition of the communication line is good, reduce the number of reception completion detections at the Orbcom mobile communication terminal; if the communication line condition is poor, increase the number of reception completion detections at the Orbcom mobile communication terminal. Therefore, an advantageous effect that efficient operation of the communication system becomes possible is obtained.

According to the Orbcom communication system of the fourth aspect, in the Orbcom communication system of the second aspect, the central processing unit controls the number of times of transmitting Final ACK to increase or decrease according to the state of the communication line. Accordingly, when the state of the communication line is good, the number of reception completion detections on the satellite side can be reduced, and when the state of the communication line is bad, the number of reception completion detections on the satellite side can be increased. Therefore, an advantageous effect that efficient operation of the communication system is enabled is obtained.

According to the Orbcom communication system according to the fifth aspect, in the Orbcom communication system according to the first or third aspect, the satellite transmits the final ACK.
In the case of a plurality of final ACKs, the transmission time interval for transmitting a plurality of Final ACKs is increased or decreased according to the state of the communication line, thereby shortening the transmission time interval when the communication line is good, and An advantageous effect is obtained in that the transmission time interval can be shortened to increase the possibility of detecting the completion of reception at the Orbcom mobile communication terminal.

According to the orbcom communication system according to the sixth aspect, in the orbcom communication system according to the second or fourth aspect, the central processing unit transmits the final signal to be transmitted.
When there are a plurality of ACKs, the time interval for transmitting a plurality of Final ACKs is increased or decreased according to the state of the communication line, so that the transmission time interval is shortened when the communication line is good, and when the communication line is defective. Has the advantageous effect of shortening the transmission time interval and increasing the possibility of detecting the completion of reception on the satellite.

According to the Orbcom communication system of the seventh aspect, in the Orbcom communication system of the first, third or fifth aspect, the central processing unit assigns a unique management number to each uplink message and performs transmission. After completing the transmission protocol, inquire the satellite of the completion of transmission of the transmission message using the management number after the completion of the transmission protocol, delete the transmission completion message in the transmission queue if transmission is completed, and retransmit if not completed Accordingly, when transmission is completed, retransmission of the same data can be prevented, so that an advantageous effect that multiplex transmission in the Orbcom mobile communication terminal can be prevented can be obtained.

According to the Orbcom communication system according to the eighth aspect, in the Orbcom communication system according to the second, fourth or sixth aspect, the base station assigns a unique management number to each downlink message via a satellite. Performs transmission, receives transmission completion or incomplete transmission from the Orbcom mobile communication terminal in response to an inquiry about transmission completion of a transmission message using a management number performed by the satellite after completion of the transmission protocol, and erases the transmission completion message to the satellite Alternatively, by requesting retransmission of a transmission incomplete message, retransmission of the same data can be prevented in the case of transmission completion, so that an advantageous effect that multiplex transmission in a satellite can be avoided can be obtained. .

According to the Orbcom communication system according to the ninth aspect, in the Orbcom communication system according to the second, fourth, sixth or eighth aspect, the central processing unit includes a unique management number and a unique management number assigned to each downlink message. At the same time, the received message is stored, responding to a received / unreceived inquiry using the management number from the satellite, and notifying that the same message has been received when the same message has been transmitted, If the data has already been received, the same data can be prevented from being re-received, so that an advantageous effect that multiplex reception in the Orbcom mobile communication terminal can be prevented can be obtained.

According to the Orbcom communication system of the tenth aspect, in the Orbcom communication system of the first, third, fifth or seventh aspect, the central processing unit assigns a unique management number to each uplink message. Performs transmission and sends an inquiry to the satellite after the completion of the transmission protocol using the management number to confirm the completion of the transmission of the message.The transmission completion inquiry is terminated when the communication status is poor or the satellite is about to sink. By performing only the transmission message that has not been transmitted, the transmission completion inquiry is performed only for the transmission message for which the protocol has not been completed. Therefore, the advantageous effect that the inquiry becomes efficient can be obtained.

According to the Orbcom communication system according to the eleventh aspect, in the Orbcom communication system according to the first, third, fifth, seventh or tenth aspect, the central processing unit has a non-volatile memory such as a backup memory. Even if the transmission result of the transmission message is being checked, it is stored in the non-volatile memory together with the management number unique to the upstream message, and even if the power of the Orbcom mobile communication terminal is turned off before the transmission processing is completed, When the power is turned on next time, the transmission result of the transmission message stored in the non-volatile memory is checked again, so that the double transmission can be prevented even if the power is interrupted during the communication. can get.

According to the Orbcom communication system according to the twelfth aspect, in the Orbcom communication system according to the second, fourth, sixth, eighth or ninth aspect, the central processing unit has a non-volatile memory such as a backup memory. The received downlink message is stored in a non-volatile memory together with a unique management number, and even if the communication is interrupted by the power off of the Orbcom mobile communication terminal before the satellite-side transmission processing is completed, the next communication is restarted. When the power is turned off during communication by comparing the unique number of the downlink message stored in the non-volatile memory with the unique number included in the downlink message from the satellite at the time of the , An advantageous effect that double reception can be prevented can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a general Orbcom mobile communication terminal.

FIG. 2 is a sequence diagram in which Final ACK is increased during transmission.

FIG. 3 is a graph showing the number of Final ACK transmissions according to a communication state in an Orbcom mobile communication terminal.

FIG. 4 is a sequence diagram in which Final ACK is increased during reception.

FIG. 5 is a graph showing a transmission interval of Final ACK according to a communication state.

FIG. 6 is a communication procedure diagram showing a transmission communication procedure according to Embodiment 2 of the present invention.

FIG. 7 is a communication procedure diagram showing a transmission communication procedure according to Embodiment 2 of the present invention.

FIG. 8 is a flowchart showing transmission processing according to Embodiment 2 of the present invention.

FIG. 9 is a format diagram showing a format of a transmission message;

FIG. 10 is a management data diagram showing internal management of a transmission message.

FIG. 11 is a communication procedure diagram showing a reception communication procedure according to Embodiment 3 of the present invention.

FIG. 12 is a communication procedure diagram showing a reception communication procedure according to Embodiment 3 of the present invention.

FIG. 13 is a flowchart showing reception processing according to Embodiment 3 of the present invention.

FIG. 14 is a format diagram showing a format of a received message;

FIG. 15 is a management data diagram showing internal management of a received message.

FIG. 16 is a sequence diagram of normal uplink message transmission.

FIG. 17 is a sequence diagram of normal downlink message reception.

FIG. 18 is a sequence diagram of double transmission during uplink communication.

FIG. 19 is a sequence diagram of double reception during downlink communication.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 central processing unit 2 program storage unit 3 rewritable memory 4 transmission message storage memory 5 reception message storage memory 6 antenna 7 wireless transmission / reception circuit (satellite transmission / reception circuit) 8 transmission queue 12 reception queue

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04Q 7/26 7/30 (72) Inventor Kazuo Hirahara 1006 Kazuma Kazuma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Toshihiro Inoue 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd.F-term (reference) EE10 GG07 HH24 HH25 HH28 5K072 AA16 BB02 BB13 BB22 EE06 FF04 GG12 GG13 GG14

Claims (12)

[Claims] An orbcom mobile communication terminal having a satellite, a satellite transmission / reception circuit for transmitting / receiving to / from the satellite, and a central processing unit for controlling transmission / reception processing; and the orbcom mobile communication terminal connected to a general communication line on the ground. An orbcom communication system comprising a base station that communicates with the orbcom mobile communication terminal using a protocol. Fin that is the reception completion notification for the message
An orbcom communication system wherein the number of times of transmission of al ACK is controlled to increase or decrease. 2. An Orbcom mobile communication terminal having a satellite, a satellite transmitting / receiving circuit for transmitting and receiving to and from the satellite, and a central processing unit for controlling the whole, and an Orbcom mobile communication terminal connected to a general communication line on the ground. An Orbcom communication system comprising: a base station that communicates with the base station via the satellite, wherein the central processing unit controls increase / decrease of the number of times of transmission of Final ACK that is a reception completion notification for a downlink message. Orbcom communication system. 3. The orbcom communication system according to claim 1, wherein the satellite controls the number of times of transmitting Final ACK in accordance with the state of a communication line. 4. The computer according to claim 1, wherein said central processing unit is a Final ACK.
3. The orbcom communication system according to claim 2, wherein the number of times of transmitting is controlled to increase or decrease according to the state of the communication line. 5. The satellite transmits a Final ACK.
4. The orbcom communication system according to claim 1, wherein when there are a plurality of ACKs, the time interval for transmitting the plurality of Final ACKs is increased or decreased according to a state of a communication line. 6. The central processing unit according to claim 1, further comprising:
If there are a plurality of ACKs, the plurality of Final ACKs
5. The orbcom communication system according to claim 2, wherein a time interval for transmitting the communication is increased or decreased according to a state of the communication line. 7. The central processing unit performs transmission by assigning a unique management number to each uplink message and, after completing a transmission protocol, inquires the satellite of the completion of transmission of the transmission message using the management number. 6. The Orbcom communication system according to claim 1, wherein if the transmission is completed, the transmission completion message in the transmission queue is deleted, and if the transmission is not completed, the transmission is performed again. 8. The base station performs transmission by assigning a unique management number to each downlink message via the satellite, and after completion of a transmission protocol, completes transmission of a transmission message using the management number performed from the satellite. 3. A transmission completion or transmission non-completion from the Orbcom mobile communication terminal in response to an inquiry, and requesting the satellite to delete the transmission completion message or retransmit the transmission non-completion message to the satellite. 7. The Orbcom communication system according to 4 or 6. 9. The central processing unit stores a received message at the same time as a unique management number assigned to each downlink message, and receives / receives a message using a management number from the satellite.
9. The Orbcom communication system according to claim 2, wherein a response is made to an unreceived inquiry, and when the same message has been transmitted, the fact that the same message has been received is notified. 10. The central processing unit performs transmission by assigning a unique management number to each uplink message, and after completion of a transmission protocol, inquires of the satellite about the completion of transmission of the transmission message using the management number. 8. The method according to claim 1, wherein the transmission completion inquiry is performed only for a transmission message whose protocol has not been completed when the communication state is poor or when the satellite is approaching. An Orbcom communication system according to claim 1. 11. The central processing unit has a non-volatile memory such as a backup memory, and stores in the non-volatile memory that a transmission result of a transmission message is being checked together with a management number unique to an uplink message. Even if the power of the Orbcom mobile communication terminal is turned off before the transmission processing is completed, the transmission result of the transmission message stored in the non-volatile memory is checked again when the power is turned on next time. Claim 1, characterized in that:
11. The Orbcom communication system according to 3, 5, 7, or 10. 12. The central processing unit has a non-volatile memory such as a backup memory, stores the received downlink message together with a unique management number in the non-volatile memory, and completes the transmission process on the satellite side. Even if the communication is interrupted due to the power off of the Orbcom mobile communication terminal before being performed, the unique number of the downstream message stored in the nonvolatile memory and the downstream message from the satellite are included when the next communication is restarted. 10. The orbcom communication system according to claim 2, wherein it is determined whether or not the messages are the same by comparing with a unique number.