JP2000101677A - Half-duplex communication system and communication terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption by determining the highest transmission rate that both devices are adaptive, performing a half-duplex communication and finding the transmission error rate, determining the next slow transmission rate that both devices are adaptive when the found rate exceeds a reference value, and performing a subsequent half-duplex communication, and carrying out a communication at a proper transmission rate during the communication. SOLUTION: When device A communicates at a transmission rate of 38.4 kbps, device B calculates the bit error rate. The calculation result is supplied to a CPU:11. The CPU:11 detects whether or not the given bit error rate exceeds the reference value, if needed, for lowering the transmission rate. In this case, communication is carried on at the transmission rate when the error rate is not larger than the reference value. But when not, whether or not this device has a transmission rate slower than the currently employed transmission rate as its adaptive transmission speed is detected, and transmission is carried on at the current rate if the transmission rate can not be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, IrD
The present invention relates to an improvement of a half-duplex communication system such as A (Infraed Data Association) communication, and also relates to a communication terminal device for realizing the half-duplex communication system.

[0002]

2. Description of the Related Art In IrDA communication, as shown in FIG. 8, when a device A and a device B communicate with each other, the device on the transmitting side is set to 5 ms to 500 ms (denoted by t1 to t4).
It is stipulated that switching is performed every time. And
At the beginning of communication, a predetermined 9.6 kbps
Stipulates that they communicate with each other.

[0003] The initial communication (denoted by t1 and t2)
In the above, the transmitting device (here, A) informs the other party of the transmission speed that can be supported by the own device, and the device (here, B) that has received the notification supports both the device A and the own device B. The highest common transmission rate among the possible transmission rates is selected and notified to the device A. Thereby, in the example of FIG.
Subsequent communication is performed at a transmission rate of 8.4 kbps.

Incidentally, the IrDA standard is IrDA1.0 shown in FIG. 9 and IrD1.0 shown in FIGS.
A1.1 exists. IrDA1.0 shown in FIG. 9 has a transmission rate of 2.4 kbps, 9.6 kbps, 19.2 kbps.
bps, 38.4 kbps, 57.6 kbps, 11
When transmitting data bits as shown in FIG. 9A, the light emission time is 1/16 of the bit time determined by each transmission speed, or 1.6 μs regardless of the transmission speed. Activate the element to emit data "0"
Send The transmission of the data “1” does not cause the light emitting element to emit light. The frame format is as shown in FIG.
As shown in (1), it starts with BOF indicating the beginning of the frame and ends with EOF indicating the end of the frame. BOF
Then, an address, a control unit, an information unit, and an FCS (frame check sequence) are set. This frame is transmitted by the step synchronization method.

[0005] IrDA1.1 shown in FIG.
This is a standard for 76 kbps and 1.152 Mbps. When transmitting data bits as shown in FIG.
During a period of / 4, the light emitting element is caused to emit light and data "0" is transmitted. The transmission of the data “1” does not cause the light emitting element to emit light. As shown in FIG. 10B, the frame format starts with STA indicating the head of the frame.
The process ends with STO indicating the end of the frame. Following the STA, an address, a control unit, an information unit, and an FCS (frame check sequence) are set. This frame is H
It is transmitted by the DLC procedure.

[0006] IrDA1.1 shown in FIG.
This is a standard related to Mbps. When transmitting a data bit as shown in FIG. 11A, the light emitting element is made to emit light for 125 ns and data "0" is transmitted. For transmission of data “1”, no light is emitted. Also,
As shown in FIG. 11B, the frame format starts with PA indicating the head of the frame and ends with STO indicating the end of the frame. PA followed by address,
The control section, I (information section), and CRC (error correction code) are set. This frame is transmitted according to the HDLC procedure.

[0007] However, even in the case where several transmission speeds as described above can be supported, the conventional IrDA communication has a common highest transmission speed among the transmission speeds that the two devices can support as described above. After selecting, communication is merely performed at the selected transmission speed, and the transmission speed is not changed until communication ends even if the communication quality deteriorates.

[0008]

For this reason, there has been a problem that erroneous data is transmitted or retransmission is required, and a long communication time is required. Half-duplex communication such as the above-mentioned IrDA communication has been applied to mobile communication terminals and the like in recent years. Such terminals are battery-powered, and an increase in power consumption due to an increase in communication time reduces the operation time of the terminal. There was a problem of doing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems in the half-duplex communication system.
To provide a half-duplex communication method and a communication terminal device capable of changing a transmission rate in accordance with communication quality, reducing an opportunity of performing retransmission by performing communication at an appropriate transmission rate, and reducing power consumption. It is.

[0010]

In the half-duplex communication system according to the present invention, at the start of communication, both devices perform half-duplex communication at a predetermined transmission speed, and in this communication, both devices perform communication. Both of the available transmission rates determine the fastest transmission rate that both can support, and then perform half-duplex communication.In the subsequent communication, the transmission error rate is obtained, and the transmission error rate is determined by the transmission rate. When the reference value to be reduced is equal to or more than the reference value to be reduced, the next slowest transmission speed that both of the transmission speeds that both devices can support can be determined and the subsequent half-duplex communication is performed. The transmission error rate is determined, and when the transmission error rate is equal to or more than a reference value for lowering the transmission rate, the next lowest transmission rate that both of the transmission rates that can be supported by both devices can cope is determined. decide Write, the transmission error rate, becomes equal to or less than the reference value to increase the transmission rate, said both device determines one fast transmission speeds of the corresponding possible transmission rate,
The subsequent half-duplex communication is performed. As a result, during the communication, the transmission speed is reduced or increased in accordance with the transmission error rate, and communication is performed at an appropriate transmission speed.

[0011] In the communication terminal device according to the present invention, at the start of communication, both devices perform half-duplex communication at a predetermined transmission speed. Initial communication means for determining the fastest transmission speed that both can cope with and then performing half-duplex communication, error rate calculation means for obtaining a transmission error rate in communication,
When the error rate calculated by the transmission error rate calculation means is equal to or more than a reference value to reduce the transmission rate, the next slowest transmission rate that both of the transmission rates that can be supported by both devices can correspond to When the error rate determined by the speed reducing means for determining and subsequently performing the half-duplex communication and the error rate calculated by the transmission error rate calculating means are equal to or less than a reference value at which the transmission rate should be increased, the transmission that both devices can support is performed. A speed increasing means for determining one higher transmission speed among the speeds and performing half-duplex communication thereafter. As a result, during the communication, the transmission speed is reduced or increased in accordance with the transmission error rate, and communication is performed at an appropriate transmission speed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A half-duplex communication system and a communication terminal according to an embodiment of the present invention will be described below with reference to the accompanying drawings. The communication system of the present invention is applied to a system as shown in FIG. For example, in order for the personal computer 1 and the mobile phone 2 to perform IrDA communication, Ir
DA modules 3 and 4 are provided. The mobile phone 2
It has a data communication function and communicates with the base station 5 via a wireless line.

FIG. 2 shows a configuration of a main part related to the present invention in the configuration of the personal computer 1 or the mobile phone 2. As shown in FIG. The information processing unit 10 shown in FIG. 1 is a processing unit for realizing essential functions provided in the personal computer 1 or the mobile phone 2. For example, the personal computer 1 uses a keyboard, a mouse, a scanner, and the like. It is used to edit the information inputted by the user and to process the information obtained by the communication. The mobile phone 2 is a portion including a radio unit, a modem unit, a TDMA unit, a codec, a handset, and the like.

The CPU 11 monitors IrDA communication and controls each unit. The frame assembling unit 12 controls the information to be transmitted under the control of the CPU 11 in FIGS.
The frame is transmitted as one of the frame formats shown in FIG. The IrDA modulation / demodulation unit 13 modulates / demodulates a frame. Each of the IrDA modules 3 and 4 has a light emitting element 14 and a light receiving element 15,
Under the control of the CPU 11, a signal coming from the IrDA modulator / demodulator 13 is transmitted from the light emitting element 14 with necessary power,
Further, the optical signal arriving is received by the light receiving element 15 and transmitted to the IrDA modulation / demodulation unit 13 as an electric signal of necessary power.

Further, a speed control unit 16 is connected to the CPU 11, and based on an instruction from the CPU 11, an IrDA
It controls the modulation / demodulation unit 13 for changing the transmission speed. This speed control is performed, for example, by the operation of the flowchart shown in FIG. First, the personal computer 1 and the mobile phone 2 perform communication at a transmission speed of 9.6 kbps, and perform communication by setting the highest transmission speed among the transmission speeds that both devices can support (S).
1). In FIG. 4, the communication is started from the device A (the mobile phone 2 in the example of FIG. 1) during the time indicated by t1 in FIG. 4, and all the transmission speeds that the device can support are notified.
Then, the device B (the personal computer 1 in the example of FIG. 1) receives this, compares the transmitted transmission speed with the transmission speed that can be supported by the own device, and determines the highest transmission speed among the transmission speeds that can be commonly supported. The transmission rate is selected, and the selected transmission rate (here, the transmission rate) to the device B as the partner device during the time t2.
38.4 kbps).

As described above, the device A performs communication at a transmission rate of 38.4 kbps as shown in FIG. At this time, the device B calculates a bit error rate (the same meaning as “transmission error rate” and “reception error rate”) as shown in step S2 of FIG. 3 (S2). In particular,
In the configuration of FIG. 2, for example, the information processing unit 10 calculates a bit error rate using FCS and CRC included in a frame. This calculation result is provided to the CPU 11. The CPU 11 detects whether or not the given bit error rate is equal to or higher than a reference value for lowering the transmission speed (S3). At this time, if the transmission speed is not higher than the reference value, communication is continued at the transmission speed.If the transmission speed is higher than the reference value, whether or not the transmission speed can be reduced is determined by a transmission speed lower than the currently adopted transmission speed. Is detected based on whether or not the own device has a transmission speed that can be supported (S
4) If the transmission speed cannot be reduced, communication is continued at the current transmission speed.

[0017] On the other hand, if the transmission speed can be reduced, of the transmission speeds that both devices can support,
Next, transmit the frame with the slow transmission rate information set,
The speed is changed (S5). For example, the control unit shown in FIG. 5 in the frame is set to indicate that the frame includes the information on the change of the transmission rate, and the information section includes the information on the transmission rate. The information of the transmission rate included in the information section includes IrDA
Each transmission rate of the standard is made to correspond to the bit of FIG.
"1" is set when the response is possible, and "0" is set when the response is impossible. The example in FIG. 5B indicates that the device can support up to 57.6 kbps. Then, as shown in FIG. 4, communication is performed at 38.4 kbps, and when it is detected that the reception error rate (error bit rate) is equal to or more than a specified value (t1).
1) Although the transmission rate is actually as shown in FIG. 5B, in the transmission rate information frame at time t12, as shown in FIG.
A frame indicating that the device can handle up to 2 kbps is set and a frame is transmitted. In the subsequent communication (t13), communication is performed at a transmission rate of 19.2 kbps.

The device A calculates the bit error rate as shown in step S6 of the flowchart of FIG. 3 and detects whether the bit rate is equal to or higher than a reference value at which the transmission speed should be reduced (S7). Here, if it is equal to or more than the reference value, step S
4, the operation is continued. If the bit error rate is not below the reference value, it is detected whether the obtained bit error rate is equal to or lower than the reference value for increasing the transmission speed (S8). This step S8
In the case where it is detected that the transmission speed is equal to or less than the reference value, whether or not the transmission speed can be increased is determined as a transmission speed higher than the currently adopted transmission speed, as a transmission speed that can be supported by the own device. If the transmission rate cannot be increased (S9), the communication is continued at the current transmission rate.

On the other hand, if the transmission speed can be increased, the transmission speed which can be supported by both devices is as follows:
Next, transmit a frame with information on the fastest transmission rate,
The speed is changed (S10). As described above, the control unit shown in FIG. 5 in the frame is set to indicate that the frame includes the information on the change of the transmission rate, and the information section includes the information on the transmission rate. As shown in FIG. 4, communication is performed with the transmission speed lowered to 19.2 kbps, and when it is detected that the reception error rate (error bit rate) is equal to or less than a specified value (t)
14), in the transmission rate information frame at time t15, as shown in FIG. 5D, 38.4 kbp
A frame indicating that the device can support up to s is set, and the frame is transmitted (t15). In the subsequent communication (t16), communication is performed at a transmission rate of 38.4 kbps.

The device B also calculates the bit error rate as shown in step S6 of the flowchart of FIG. 3 and detects whether the transmission speed is equal to or higher than a reference value for lowering the transmission speed (S7). If the value is equal to or more than the reference value, the process returns to step S4 to continue the operation. If the value is not less than the reference value, it is detected whether the obtained bit error rate is equal to or less than the reference value for increasing the transmission speed (S8). . Here, if it is equal to or less than the reference value, it is detected whether or not the speed can be increased (S9). That is, in this step S9, it is detected whether or not the own device has a transmission speed higher than the currently adopted transmission speed as a compatible transmission speed. As a result of this detection, if the transmission rate cannot be increased, communication is continued at the current transmission rate. In the example of FIG. 4, the reception error rate (bit error rate) is restored to the reference value. However, since there is no transmission rate that can cope with the current transmission rate, it is determined that communication is to be continued at the current transmission rate. (T17), time t
In the transmission rate information frame in FIG.
As shown in (d), a frame indicating that the device can support up to 38.4 kbps is set and a frame is transmitted (t18), and subsequent communication is also performed (t19).
Communication is performed at a transmission rate of 38.4 kbps.

When a decrease in communication quality is detected as described above, the transmission speed is reduced, so that the pulse width is widened, which causes an error when data is decoded before the transmission speed is reduced. Even if a certain degree of noise occurs, correct decoding can be performed. For example, FIG.
As shown in the table, the pulse width with respect to the bit time is widened, and before the transmission speed is reduced, it is determined that the pulse has risen during the detection of n sampling clocks. When the pulse rises during the detection of the m (m> n) sampling clocks due to the decrease in the value of "n", it is determined to be "0". Therefore, even if noise corresponding to n times as shown in FIG. , Can be decoded exactly as “1”. Also, as shown in FIG. 7, when a noise that increases the pulse width occurs, the pulse rises while detecting the sampling clock of m (m> n) times, so that “0” is set. Since the judgment is made, no error occurs.

In the above-described embodiment, the transmission rate information frame is transmitted from any of the communicating devices to change the transmission rate. In the example of 4, only the device B) may transmit the transmission speed information frame and change the transmission speed. Alternatively, only the transmitting side (device A in the example of FIG. 4) may transmit the transmission rate information frame and change the transmission rate. Further, after transmitting the transmission rate information frame, the transmitting side changes the transmission rate, but the side receiving the transmission rate information frame changes the transmission rate based on the contents of the frame to perform communication. May be.

As described above, according to the embodiment of the present invention, the bit rate can be prevented by lowering the transmission speed, so that retransmission is unnecessary and the communication time can be reduced. When the half-duplex communication such as the IrDA communication described above is applied to a mobile communication terminal or the like, such a terminal is battery-powered, and can prevent an increase in communication time, thereby preventing an increase in power consumption and reducing the operation time of the terminal. Never. In addition, since the transmission speed is changed according to the communication quality and communication is performed at an appropriate transmission speed, the transmission speed is not kept reduced, so that the communication time can be shortened and the power consumption can be reduced. .

[0024]

As described above, according to the half-duplex communication method according to the present invention, the transmission rate is reduced or increased by the transmission error rate, and communication is performed at an appropriate transmission rate. In addition, transmission errors can be reduced, the transmission speed does not remain low, and the communication time can be shortened.

As described above, according to the communication terminal apparatus of the present invention, the transmission rate is reduced or increased by the transmission error rate, and communication is performed at an appropriate transmission rate. The transmission speed can be reduced, the transmission speed does not remain low, the communication time can be shortened, and the power consumption can be reduced. Therefore, the communication time can be lengthened in the case of battery drive.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a communication system to which a half-duplex communication system according to the present invention is applied.

FIG. 2 is a configuration diagram of a communication terminal device according to the present invention.

FIG. 3 is a flowchart for explaining a communication operation of the communication terminal device according to the present invention.

FIG. 4 is a diagram showing a communication procedure according to the half-duplex communication method according to the present invention.

FIG. 5 is a diagram showing a main part in a frame when a transmission speed is notified in communication by the half-duplex communication method according to the present invention.

FIG. 6 is a diagram showing that communication by the half-duplex communication method according to the present invention is not easily affected by noise.

FIG. 7 is a diagram showing that communication by the half-duplex communication method according to the present invention is not easily affected by noise.

FIG. 8 is a diagram showing a communication procedure using a half-duplex communication method according to a conventional example.

FIG. 9 is a diagram for explaining a pulse width and a frame format of the IrDA standard.

FIG. 10 is a diagram for explaining a pulse width and a frame format of the IrDA standard.

FIG. 11 is a diagram for explaining a pulse width and a frame format of the IrDA standard.

FIG. 12 is a diagram showing the influence of noise in communication by a half-duplex communication method according to a conventional example.

FIG. 13 is a diagram showing an influence of noise in communication by a half-duplex communication method according to a conventional example.

[Explanation of symbols]

Reference Signs List 1 personal computer 2 mobile phone 3, 4 IrDA module 5 base station 10 information processing unit 11 CPU 12 frame assembly unit 13 IrDA modulation / demodulation unit 14 light emitting element 15 light receiving element 16 speed control unit

Claims (4)

[Claims] 1. At the start of communication, both devices perform half-duplex communication at a predetermined transmission speed, and in this communication, the highest speed that both of the transmission speeds that both devices can support can be used. Determine the transmission speed and perform the subsequent half-duplex communication.In the subsequent communication, determine the transmission error rate.If the transmission error rate is equal to or higher than the reference value at which the transmission speed should be reduced, both devices respond. The next lowest transmission rate that both of the possible transmission rates can cope with is determined and the subsequent half-duplex communication is performed.In the subsequent communication, the transmission error rate is determined, and the transmission error rate When the speed is equal to or higher than the reference value to be reduced, the transmission error rate increases the transmission speed while determining the next slowest transmission speed that both of the transmission speeds that both devices can support can cope with. When the less should the reference value, a half-duplex communication method, wherein said both device determines one fast transmission speeds of the possible corresponding transmission speed, performs the subsequent half-duplex communication. 2. Initially, the device notifies the other party of all the transmission speeds that can be supported by the device, and when the transmission error rate becomes equal to or higher than a reference value for lowering the transmission speed, the currently used transmission is performed. Notifies that it is possible to support a transmission rate lower than the transmission rate.If the transmission error rate falls below the reference value at which the transmission rate should be increased, it indicates that it is possible to support a transmission rate higher than the currently used transmission rate. The half-duplex communication method according to claim 1, wherein the notification is performed. 3. At the start of communication, both devices perform half-duplex communication at a predetermined transmission speed, and in this communication, the highest speed that can be supported by both of the transmission speeds that can be supported by both devices. Initial communication means for determining the transmission speed and performing the subsequent half-duplex communication, transmission error rate calculation means for determining the transmission error rate in communication, and the error rate determined by the transmission error rate calculation means lowers the transmission rate. If the transmission speed is equal to or more than the reference value to be performed, a speed reduction unit that determines the next lowest transmission speed that both of the transmission speeds can support and that performs half-duplex communication thereafter, When the error rate obtained by the rate calculating means is equal to or less than a reference value at which the transmission rate should be increased, one of the transmission rates that can be supported by the two devices is determined, and then the half-duplex communication is performed. A communication terminal device comprising: a speed increasing unit for performing 4. A transmission rate notifying means for notifying a transmission rate which can be supported by the own apparatus, wherein the speed notification means initially notifies the other party of all transmission rates which can be supported by the own apparatus, and a transmission error rate. However, when the transmission rate is equal to or higher than the reference value to reduce the transmission rate, it notifies that it is possible to support a transmission rate lower than the currently used transmission rate, and the transmission error rate becomes equal to or less than the reference value to increase the transmission rate. 4. The communication terminal apparatus according to claim 3, wherein the communication terminal apparatus notifies that the transmission rate is higher than the currently used transmission rate.