JP2001257692A - Communication method and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly set a frame cycle to a standard time when a radio LAN is formed. SOLUTION: When the data are structuralized into frames and periodically transmitted by radio between a controller and one or more terminal devices, the controller controls the transmission cycle of the data structurized into frames and a difference signal between the standard time information and the transmission cycle is obtained by a comparator 108 as an error signal. Then the controller corrects the transmission cycle of the data structurized into frames according to the difference signal. When this correction of transmission cycle is carried out, a filter 120 functions as a limiter that limits the amount of change to a value smaller than a prescribed amount per unit period of the frame cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method suitable for a wireless network for a local area network (LAN) composed of a control device and a terminal device, and a communication method suitable for the communication method. The present invention relates to a communication device to which the present invention is applied, and particularly to a technology for setting frame synchronization.

[0002]

2. Description of the Related Art Conventionally, a wireless LAN has been set up by a plurality of wireless communication devices within a relatively narrow range. FIG. 7 is a diagram showing a configuration example of the network. Here, the network is configured by three wireless communication devices 1, 2, and 3. Of the three wireless communication devices 1 to 3, one wireless communication device 1 is set as a control device for controlling wireless communication, and the remaining two wireless communication devices 2 and 3 This is a terminal device that performs communication in synchronization with a frame cycle set by the device.

That is, the communication device 1 as a control device periodically transmits a frame synchronization signal to the communication devices 2 and 3 as terminal devices and causes the communication devices 1, 2, and 3 to transmit data. , Data is transmitted in a data transmission section set by the frame synchronization signal, and is received by another communication device.

[0004] With such a network configuration, data transmission can be favorably performed while maintaining the frame period.

[0005]

By the way, there is a case where a frame cycle set for wireless communication in such a network is synchronized with time information serving as a reference. In such a case, if the frame period is simply corrected based on the time information, if the frame period greatly deviates from the reference time for some reason, the frame period greatly fluctuates, and the frame setting state is disturbed. There was a problem. In such a case, the synchronization accuracy between the communication devices in the network deteriorates.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to satisfactorily perform a process for adjusting a frame cycle to a reference time in this kind of LAN.

[0007]

According to the present invention, there is provided a control apparatus comprising:
Between one or more terminal devices, when the predetermined data is frame-structured and periodically wirelessly transmitted, the control device controls the transmission period of the frame-structured data, and the reference time information and Obtain an error signal comparing the transmission periods,
The control device corrects the transmission cycle of the frame structured data based on the error signal, and limits the variation per unit period of the frame cycle to a predetermined amount or less when performing the correction. It is.

According to the invention, the frame period is corrected based on the reference time information, and the correction amount per unit period when the correction is performed is limited to a predetermined amount or less. , Rapid fluctuation of the frame period can be prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing a system configuration of the present embodiment. In this example, three wireless communication devices 100, 20
This is a wireless LAN in which a network is configured by 0,300. Of the three wireless communication devices 100 to 300, one wireless communication device 100 is set as a control device for controlling wireless communication, and the remaining two wireless communication devices 20
Reference numerals 0 and 300 denote terminal devices that perform communication in synchronization with a frame period set by the control device. In the following description, the communication device 100 is referred to as a control device, and the communication devices 200 and 300 are referred to as terminal devices.

That is, the control device 100 controls the terminal device 20
0, 300, a cycle start packet corresponding to a frame synchronization signal is periodically transmitted to the control device 100.
Alternatively, when transmitting data from the terminal devices 200 and 300, the data area set in the frame period
The data is transmitted and received by another communication device.

Here, a time information source 10 is connected to the control device 100 of the present embodiment, and time information serving as a reference is obtained from the time information source 10. Time information source 10
For example, a means for measuring a reference time such as a radio clock is provided, and a periodic pulse is output based on the time measured by the measuring means. For example, a pulse of a cycle corresponding to the frame cycle set by the control device 100 (or a pulse of an integral multiple of the cycle)
Is output in synchronization with the measured time. A pulse synchronized with this time is input to the control device 100.

Note that the time information source 10 may be another reference device connected to the control device 100 via a cable bus. For example, if the control device 100
EEE (The Institute of Electrical and Electronic
s Engineers) A device connected to a bus line defined as the 1394 system and functioning as a cycle master on the bus line is set as a time information source 10, and a transmission cycle on the bus set by the cycle master is set as a reference. May be used as time information.

Next, the configuration of the control device 100 will be described with reference to FIG. The control device 100, which is a wireless communication device,
An input terminal 101 for transmitting data is provided.
01 is supplied to a transmission system circuit 102, a transmission process is performed to generate a transmission signal of a predetermined method, and the processed transmission signal is supplied to an antenna 104 via an antenna duplexer 103. Wireless transmission. At the time of transmission processing in the transmission system circuit 102, management data including synchronization data is generated in synchronization with the timing pulse supplied from the frame period generation circuit 111, so that the management data is included in a signal to be wirelessly transmitted. It is. The configuration of transmission data such as management data will be described later. Also, the antenna 104 has the antenna duplexer 1
A receiving system circuit 105 is connected via the input circuit 03, and reception data obtained by receiving a radio signal by the receiving system circuit 105 is output from an output terminal 106.

Further, the control device 100 of this embodiment has a reference time information input terminal 107, and a pulse output from the time information source 10 is supplied to this input terminal 107 as reference time information. A pulse synchronized with the time obtained at the input terminal 107 is supplied to one input terminal of the phase comparator 108. A pulse output from the frame period generating circuit 111 is supplied to the other input terminal of the phase comparator 108, and the phase comparator 108 detects an error signal based on a phase difference between the two pulses. The detected error signal is supplied to one fixed contact 109a of the changeover switch 109.

The other fixed contact 10 of the changeover switch 109
9b is connected to the receiving system circuit 105. When data received by the receiving system circuit 105 includes phase error data, the phase error data is extracted and supplied to the other fixed contact 109b. is there. Changeover switch 10
9 is one fixed contact 1 in this example.
09a. The case where the movable contact 109m is connected to the other fixed contact 109b is a case where the time information source 10 is connected to the terminal device 200 or 300 side, and this example will be described in a second embodiment described later. .

The movable contact 1 of the changeover switch 109
The signal obtained at 09m is supplied to the loop filter 120. The configuration of the loop filter 120 will be described later.

The output of the loop filter 120 is supplied to a frame synchronization generating circuit 111 via a connection switch 110. In the frame synchronization generation circuit 111, a process of generating a frame synchronization pulse at a constant cycle and supplying the frame synchronization pulse to the transmission system circuit 102 is performed. In this case, from the loop filter 120 to the switch 11
When the processing is supplied via the “0”, the correction processing of the frame period proportional to the level of the signal is performed. The connection switch 110 is a switch that is set to an on state when the correction of the frame period is required, and is set to an off state when the correction of the frame period is not required.

FIG. 3 is a diagram showing a configuration example of the loop filter 120. The signal obtained at the input terminal 121 is supplied to a proportional coefficient multiplier 122, where the signal is multiplied by a proportional coefficient k. Then, the output of the proportional coefficient multiplier 122 is
The signal is supplied to the adder 123 and the integration coefficient multiplier 124
And multiplies it by the integral coefficient a. Integral coefficient multiplier 12
The output of 4 is supplied to an integration circuit including an adder 125 and a delay circuit 126 to perform an integration process. The integration process here is realized by returning the output of the delay circuit 126 to the adder 125 and adding it to the input. The integration signal output from the delay circuit 126 is supplied to an adder 123 to be added to a signal directly supplied from the proportional coefficient multiplier 122. With this configuration, a value obtained by adding a numerical value proportional to the error signal and a numerical value proportional to the integral value of the error signal is obtained as the addition output of the adder 123.

The addition output of the adder 123 is supplied to the delay circuit 12
8 and a signal delayed in a plurality of stages by the limiter 1
27. The limiter 127 performs limit processing for limiting the amount of change to a certain amount or less for each predetermined unit. Specifically, for example, during 10 frame periods generated by the frame period generation circuit 111, the timing is corrected by one clock period (correction to make one clock period earlier or 1
The processing for limiting the clock period timing is performed. In the case of this example, the output of the limiter 127 is further supplied to another limiter 129 to further limit the variable range of the frame period itself. Then, the output of the limiter 129 is supplied to the output terminal 130 of the loop filter 120,
The output terminal 130 supplies the signal to the switch 110 shown in FIG.

Note that the proportional coefficient value k and the integral coefficient value a to be multiplied by the coefficient multipliers 122 and 124 in the loop filter 120 of the present embodiment are controlled by the operation of the limiter 127. That is, while the limit operation for limiting the numerical value supplied by the limiter 127 is being performed, the proportional coefficient k and the integral coefficient a are controlled to small values. For example, while the limit operation is being performed, the proportional coefficient value k is set to １ ／ of the steady state value, and the integral coefficient value a is set to 0.

Here, an example of a frame configuration of a signal wirelessly transmitted on a network under the control of the control device 100 of the present embodiment will be described with reference to FIG. A of FIG.
It shows the structure of a frame signal. In the case of this example, one frame period is set to 4 ms, and a signal having this frame structure is repeated at a cycle of 4 ms. At the beginning of one frame period, there is a management area, and the remaining section is a data area. Control device 100 and terminal device 20
If there is data to be transmitted from 0,300, the transmission data is arranged in this data area and transmitted.

As shown in FIG. 4B, the management area includes a cycle start packet (CSP), a cycle report packet (CRP), and a station sync packet (SS).
P). The cycle start packet (CSP) is a section in which the control device 100 transmits data that defines a frame cycle such as frame synchronization data. Control device 1 for this cycle start packet
00 from the frame period generation circuit 1
11 is set based on a pulse synchronized with the frame period output. Cycle report packet (CRP)
Is a section in which data related to a frame cycle such as phase error data is transmitted from the terminal device side. The station sync packet (SSP) is data necessary for synchronization between communication devices in the network.

Next, a process of correcting the frame period by the control device 100 of this embodiment will be described. First, the control device 1
00 is set to the ON state, and the phase error between the pulse synchronized with the reference time supplied from the time information source 10 and the pulse synchronized with the frame cycle generated by the frame cycle generation circuit 111 is calculated as Phase comparator 10
In step 8, detection is performed. Here, when the frame period generated in the control device 100 is completely synchronized with the reference time, the phase error signal output from the phase comparator 108 becomes a signal of a level corresponding to no error. The signal is transmitted to the frame period generation circuit 11 through the loop filter 120.
1 and the frame period is maintained as it is.

On the other hand, when the pulse synchronized with the frame period generated in the control device 100 has a phase difference with the pulse synchronized with the reference time, the phase error signal proportional to the phase difference is compared with the phase difference signal. The phase error signal detected by the detector 108 is supplied to the frame cycle generation circuit 111 via the loop filter 120, and the processing for correcting the frame cycle is performed.

At this time, in this embodiment, when a phase error signal of a certain level or more is obtained, the loop filter 12
Since the limiter 127 within 0 performs the process of limiting the amount of timing correction for each unit frame period, the frame period is corrected by the limited amount. For example, when the limiter 127 has a limitation of correcting one frame period by one clock period for ten frames, a process of correcting the frame timing by one clock period in ten frame periods is performed, and the process of correcting the frame period is executed. Is done. Therefore, a sharp change in the frame period is prevented, and the correction of the frame period is executed satisfactorily. That is, the control device 100
There is no sudden change in the timing of the cycle start packet (CSP) transmitted from the terminal device 200, 3
In the case of 00, timing correction is performed within an allowable range in which frame synchronization can be captured. Therefore, the synchronization accuracy between the control device 100 and the terminal devices 200 and 300 can be kept high.

In the present embodiment, the limiter 129 limits the variable range of the frame period itself, so that the variable range of the maximum frame phase when this correction is continued is also restricted. It is so. The limitation of the variable range by the limiter 129 may not be executed.

When such correction of the frame period is being performed, the proportional coefficient value k and the integral coefficient value a to be multiplied by the coefficient multipliers 122 and 124 in the loop filter 120 are limited to small values. Therefore, the stability of the control operation during the timing correction can be kept good. That is, while the limiter is operating, the entire loop operates like an integrator, and the entire loop becomes unstable,
Oscillation may occur in some cases. Here, in this example, the proportional coefficient value and the integral coefficient value are reduced, and the proportional gain and the integral gain are set low, thereby avoiding such a problem during the operation of the limiter and realizing a good operation. ing. When the limiter is not performing the limiting operation, the proportional coefficient value and the integral coefficient value are set as the set values so as to keep the circuit following. Therefore, while keeping the stability of the closed loop, the following performance can be maintained at the same time.

If the time information source 10 connected to the control device 100 is a cycle master of another network such as an IEEE 1394 bus line, the time period of the frame in the wireless network of the present embodiment is determined by this network. , The frame period of the other network connected to the other network can be matched well, and the synchronization of the two networks can be kept good.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 5 shows a network configuration in the case of this embodiment. In this embodiment, three wireless communication devices 100 and 200 are provided in the same manner as in the network described in the first embodiment. , 300 as a wireless LAN. One of the three wireless communication devices
Wireless communication devices 100 are set as control devices for controlling wireless communication, and the remaining two wireless communication devices 2
Reference numerals 00 and 300 are terminal devices that perform communication in synchronization with the frame period set by the control device. The control device 100 has the same configuration as the control device 100 described in the first embodiment. However, in this example, the movable contact 109m of the changeover switch 109 shown in FIG. 2 is connected to the other fixed contact 109b. The configuration of transmission data such as a frame period is the same as the configuration described in the first embodiment with reference to FIG.

In the case of this example, the terminal device 200
The time information source 10 is connected to the terminal device 200 so that the terminal device 200 obtains reference time information from the time information source 10.

FIG. 6 is a diagram showing a configuration of the terminal device 200 of the present embodiment. The terminal device 200, which is a wireless communication device,
An input terminal 201 for transmitting data is provided.
01 is supplied to the transmission system circuit 202, transmission processing is performed to generate a transmission signal of a predetermined system, and the processed transmission signal is supplied to the antenna 204 via the antenna duplexer 203. Wireless transmission. A receiving system circuit 205 is connected to the antenna 204 via an antenna duplexer 203. The receiving system circuit 205 receives a radio signal and outputs received data from an output terminal 206. is there. in this case,
During transmission processing in the transmission system circuit 202, the reception system circuit 20
The transmission processing is performed at a frame period based on the cycle start packet received at step 5.

Further, the terminal device 200 of this embodiment has a reference time information input terminal 207, and a pulse output from the time information source 10 is supplied to this input terminal 207 as reference time information. A pulse synchronized with the time obtained at the input terminal 207 is supplied to one input terminal of the phase comparator 208. A pulse synchronized with the cycle start packet received by the receiving system circuit 205 is supplied to the other input terminal of the phase comparator 208, and the phase comparator 208 detects an error signal based on the phase difference between the two pulses. The detected error signal is transmitted to the transmission system circuit 2 via the connection switch 209.
02. The connection switch 209 is a switch that is set to an on state when the time information source 10 is connected to the terminal device 200, and is set to an off state when the time information source 10 is not connected to the terminal device 200.

When the phase error signal is supplied to the transmission system circuit 202, data based on the phase error signal is arranged and transmitted in the cycle report packet section of each frame.

When the control device 100 receives the phase error data in the cycle report packet, the phase error data is received by the receiving circuit 105 shown in FIG.
Is supplied to the frame period generation circuit 111 via the loop filter 120, and the frame period is corrected based on the phase error data. The details of the frame period correction processing are the same as the processing described in the first embodiment, and the limit processing and the gain restriction processing in the loop filter 120 are performed.

As described above, the time information source 10 is provided on the terminal device side.
Is connected, and the phase difference between the frame period and the reference time is detected in the terminal device to which the time information source 10 is connected, and the phase error signal is transmitted to the control device side. As in the case of the embodiment, it is possible to satisfactorily correct the frame period. That is, while maintaining high synchronization accuracy between the control device and the terminal device, the stability of the closed loop can be ensured, and at the same time, the tracking performance can be maintained high. Since the time information source can be connected to the terminal device side as in this example, the time information source can be connected to any communication device on the network, and the degree of freedom of the network configuration is improved. .

Incidentally, also in the case of the second embodiment,
The time information source 10 may be a cycle master of another network such as an IEEE 1394 bus line. In this case, the time period of the frame in the wireless network is determined by a frame of another network connected to the terminal device 200. The period can be well matched and the two networks can be well synchronized.

The network configuration, frame configuration, and the like described in each of the above-described embodiments are merely examples, and can be applied to wireless LANs having other configurations.

[0040]

According to the present invention, the frame period is corrected based on the reference time information, and the correction amount per unit time when the correction is performed is limited to a predetermined amount or less. This can prevent a sudden change in the frame period. Therefore, it is possible to eliminate an adverse effect due to a rapid change in the setting state of the frame period,
The frame period can be corrected while maintaining high synchronization accuracy in the network.

In this case, when the restriction is performed, the gain of the signal based on the error signal is reduced, so that the correction processing based on the error signal can be performed stably. Further, when the limiting process is not performed, the process can be performed with a high gain, and the follow-up property at the normal time can be improved.

In the above case, since the reference time information is obtained by the control device, the frame period can be easily corrected by the process in the control device.

In the above case, the reference time information is obtained by a predetermined terminal device, and the time information obtained by the terminal device is transmitted to the control device. Based on the obtained time information, the control device can accurately perform the frame period correction processing.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an example of a system configuration according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating an example of a control device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating an example of a loop filter according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a configuration example of transmission data according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of a system configuration according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram illustrating an example of a terminal device according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a system configuration example of a conventional wireless LAN.

[Explanation of symbols]

10 time information source, 100 control device, 200, 300
... Terminal device, 102 ... Transmission system circuit, 105 ... Reception system circuit, 107 ... Reference time information input terminal, 108 ... Phase comparator, 111 ... Frame cycle generation circuit, 120 ... Loop filter, 202 ... Transmission system circuit, 205 ... Receiving circuit 2
07: Reference time information input terminal, 208: Phase comparator

Claims (8)

[Claims] 1. A communication method for periodically transmitting predetermined data by frame-structured radio transmission between a control device and one or more terminal devices, wherein the transmission period of the frame-structured data is The control device controls and obtains an error signal comparing the reference time information and the transmission cycle, and based on the error signal, the control device corrects the transmission cycle of the frame structured data, A communication method in which the amount of change in the frame period per unit time is limited to a predetermined amount or less when the correction is performed. 2. The communication method according to claim 1, wherein when the restriction is performed, a gain of a signal based on the error signal is reduced. 3. The communication method according to claim 1, wherein the reference time information is obtained by the control device. 4. The communication method according to claim 1, wherein the reference time information is obtained by a predetermined terminal device, and the time information obtained by the terminal device is transmitted to the control device. Communication method. 5. A frame cycle generating means for generating a frame cycle, a transmitting means for transmitting a synchronization signal at a frame cycle set by the frame cycle generating means, a time information input means for obtaining reference time information, Error detection means for obtaining an error signal between the time information obtained by the time information input means and the frame period generated by the frame means generation means; and the frame based on the error signal detected by the error detection means. Correction means for correcting the frame cycle set by the cycle generation means; and a limit for limiting the correction amount per unit period of the frame cycle in the frame cycle generation cycle by the error signal output from the error detection means to a predetermined amount or less. A communication device comprising means. 6. The communication device according to claim 5, wherein, as the limit means, when a value obtained by adding a value proportional to the error signal and a value proportional to an integral value of the error signal exceeds the predetermined amount. , A communication device configured to limit to a predetermined amount. 7. The communication device according to claim 6, wherein, when the limiting process is being performed by the limiting means, the gain of the circuit for obtaining the proportional value and the gain of the circuit for obtaining the integral value are reduced. A communication device including a gain control unit. 8. The communication device according to claim 5, wherein said time information input means is means for receiving time information wirelessly transmitted from another communication device.