JPH11145916A - Submarine acoustic data communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a submarine acoustic data communication method which attains improvement of transmission efficiency and power saving. SOLUTION: Submarine acoustic data transmission equipment 10a is composed of a transmitter/receiver 11a, MODEM part 12a and CPU 13a and reception equipment 10b is composed of a transmitter/receiver 11b, MODEM part 12b and CPU 13b. A communication protocol performs line establishment through a high level data link control (HDLC) hand shake sequence 20 and data transmission is performed by a frame request 21 and frame transmission 22. In this case, when plural frame errors occur, a multi-area rejection (MREJ) 30 is issued from the reception equipment 10b. The delivery of an MREJ frame is confirmed by a wait timer. When the MREJ is issued by the transmission equipment 10a, an out standing transmission sequence 31 of an error frame is executed. When plural frame erros occur in this sequence, the MREJ frame of an updated error frame number is issued again and the same sequence is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for communicating underwater acoustic data with high transmission efficiency and low power consumption.

[0002]

2. Description of the Related Art Various communication protocols have been adopted in the field of wired and wireless communication for data communication. However, in underwater acoustic data communication, a conventional protocol is used due to the characteristics inherent to underwater acoustic propagation. Even if used, sufficient transmission efficiency cannot be obtained. In addition, since equipment and devices used underwater are required to have extremely severe power saving performance, it is desirable to use a protocol that fully considers power consumption during communication, but this is not sufficient with the conventional method. I cannot deny the feeling of being. For example, currently wireless and WAN (Wi-Fi)
HDLC (HiLC) used in the field of
gh Level Data Link Control is one of the most desirable existing protocols in view of the above requirements.

However, when this technique is applied to underwater acoustic data communication, which is a poor communication environment in which a high noise level and a Doppler effect due to fluctuation are remarkably exhibited, the throughput is remarkably reduced due to an increase in retransmission sequences due to frequent occurrence of frame errors. Sufficient transmission efficiency cannot be obtained. Also, HD
Since the LC is not designed with a sequence for actively adapting to changes in the communication environment and is designed to constantly capture the bit error rate of the transmission path only with stochasticity, the LC is considered to be power-saving. There is also a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide an underwater acoustic data communication method capable of improving transmission efficiency and saving power. Is to provide.

[0005]

According to the first aspect of the present invention, a first step of establishing a line between a transmitting device and a receiving device, and transmitting a plurality of frames from the transmitting device to the receiving device. Transmitting a retransmission request frame including the number and the total number of error frames from the receiving apparatus to the transmitting apparatus when a plurality of frame errors occur in the second step of transmitting data and transmitting in the second step. Receiving the retransmission request frame,
Retransmitting the error frame from the transmitting device to the receiving device.

According to a second aspect of the present invention, in the underwater acoustic data communication method according to the first aspect, the arrival confirmation of the error frame in the transmitting device is performed by a wait timer. According to a third aspect of the present invention, in the underwater acoustic data communication method according to the first or second aspect, if all of the frames retransmitted in the fourth step have an error, the data is received in the third step. The retransmission frame transmitted from the device is transmitted to the transmission device again without updating the error frame number.

According to a fourth aspect of the present invention, every time data transmission for one modulo is completed by the underwater acoustic data communication method of the first aspect, the total number of frame errors is recorded, and the latest n (n: positive (Integer) The average value of the number of error frames in data transmission is calculated, and the calculated average value is compared with a preset set value. When the average value is larger than the set value, It is characterized by notifying that.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. The system, as shown in FIG.
It comprises an underwater acoustic data transmitting device 10a and an underwater acoustic data receiving device 10b. The underwater acoustic data transmission device 10a includes a transducer 11a, a modem 12a, a CPU 1
3a, and the underwater acoustic data receiving device 10
b denotes a transducer 11b, a modem 12b, a CPU 13b
It is composed of The protocol according to the present embodiment is incorporated in the CPUs 13a and 13b as software to perform communication control. The protocol establishes a line in the HDLC handshake sequence 20 (FIG. 1), and data transmission is performed from the transmitting device 10a to the receiving device 10b by a frame request 21 and a frame transmission 22. If a plurality of frame errors occur here, A multi-area rejection (MREJ) 30 is issued from the receiving device 10b.

The confirmation of the arrival of the MREJ frame in the transmitting apparatus 10a is managed by measuring the time using a wait timer, as in other control frames. M in the transmitting device 10a
When the REJ is received, the outgoing transmission procedure 31 of the error frame is executed. If a plurality of frame errors occur in this procedure, an MREJ frame with an updated error frame number is issued again, and the same procedure is repeated. If only one frame has an error in step 31, the HDLC SREJ (Selective
Rejection) frame 23 and one-frame retransmission 24. If all the frames have an error in the procedure 31, the MREJ frame 30 in which the error frame number is not updated and the frame retransmission 31 are executed.

Next, the MREJ frame format is defined below. Base frame is HDLC UI
This is a frame, and the frame header, footer, address section and control section are not particularly changed. Figure 2 in the data section
, The MREJ frame tag, the retransmission designated frame number, and the retransmission frame number are described.

The meaning of each symbol in FIG. 2 is as follows. MREJ: a specific bit pattern for identifying an MREJ frame FrNo: 1-byte notation of the total number m of frames requested to be retransmitted n1 to mn: numbers of frames requested to be retransmitted, each 1-byte notation Upper UI layer is another UI frame M to use the format
Identification is performed using the REJ frame tag. The MREJ frame data portion has a maximum variable length of M bytes, and is defined as M = modulo number + 2 (bytes).

Next, a frame error calculation procedure will be described with reference to FIG. After the HDLC handshake 20 is completed, the total number of frame errors when the data transmission procedure 41 for one modulo including the error frame retransmission procedure is completed is recorded as FEN1. If data to be sent still remains, the data transmission procedure 42 for one modulo is executed again by the same sequence, and the total number of frame errors is set to FEN2. This is all repeated until n data is transferred.

Here, a frame error rate FET allowed in data transmission for one modulo and the number of samples n are set in advance, and an arbitrary k-th data transmission procedure 44 is performed.
In the following, the following determination is made.

(Equation 1) That is, the average number of frame errors of n samples is equal to the FET
A determination is made as to whether the value exceeds or falls below the FET. If the value exceeds the FET, this is notified to the upper layer and the determination is awaited. Also FE
If it is less than T, data transmission is continued without notification. This determination processing 30 is repeatedly executed also at the time of the next (k + 1) th data transmission, and the frame error rate measurement is performed each time. With this function, communication control suitable for a change in line status over time can be performed. For example, if the sea is rough and the error rate is high, stop the communication,
Alternatively, a measure such as reducing the modulo number m becomes possible.

As described above, according to the above-described embodiment, the introduction of MREJ implements the outstanding frame transmission for the error frame retransmission sequence, and as a result, compared to the ordinary HDLC under the condition that errors frequently occur. As a result, the retransmission sequence converges in a short time, thereby improving the throughput and achieving high transmission efficiency.
This makes it possible to improve the HDLC-based communication protocol to high transmission efficiency in a poor communication environment such as underwater acoustic data communication. Further, by setting the threshold value of the frame error rate, a communication environment measurement function independent of the communication device hardware and the lower layer can be realized. By notifying the result to the upper layer,
The system can determine whether to continue the establishment of the communication line, or change the active parameters according to the line condition. As a result, when it is determined that the communication environment is extremely bad, power saving can be achieved in the entire system by performing processing such as line disconnection.

[0015]

According to the present invention, high transmission efficiency can be achieved in underwater acoustic data communication. Also,
According to the invention described in claim 4, it is possible to achieve power saving of the system.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an underwater acoustic data communication method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a format of a data portion of a retransmission frame according to the embodiment.

FIG. 3 is a flowchart showing an error rate measurement process in the embodiment.

[Explanation of symbols]

 10a Transmitting device 11a, 11b Transceiver 12a, 12b Modulator / demodulator 13a, 13b CPU 20 Handshake procedure 30 MREJ

Claims (4)

[Claims] A first step of establishing a line between a transmitting apparatus and a receiving apparatus; a second step of transmitting data by transmitting a plurality of frames from the transmitting apparatus to the receiving apparatus; When a plurality of frame errors occur in the transmission according to the process 2, the receiving device transmits the
A third step of transmitting a retransmission request frame including the number and the total number of error frames; and a fourth step of receiving the retransmission request frame and retransmitting the error frame from the transmitting device to the receiving device. An underwater acoustic data communication method, characterized in that: 2. The underwater acoustic data communication method according to claim 1, wherein the transmission device confirms the arrival of the error frame by using a wait timer. 3. When all the frames retransmitted in the fourth step have errors, the retransmitted frame transmitted from the receiving apparatus in the third step is retransmitted without updating the error frame number. The underwater acoustic data communication method according to claim 1, wherein the underwater acoustic data is transmitted to a device. 4. A frame error total number is recorded each time data transmission for one modulo is completed by the underwater acoustic data communication method according to claim 1, and is used in the latest n (n: positive integer) data transmissions. Calculating an average value of the number of error frames, comparing the calculated average value with a preset set value, and notifying that the average value is larger than the set value. Characteristic underwater acoustic data communication method.