JP2003087203A - Optical radio slave equipment for half duplex optical radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arrange more slave sets under a master set. SOLUTION: When there is a signal to be transmitted to the master set 1, an optical line transmission part 20 in a slave set 3 transmits the signal by burst light emission, and when there is no signal to be transmitted, executes DC light emission at the midpoint of burst light emission. When there is no signal to be transmitted to the master set for prescribed time, a control part 27 in the slave set interrupts the DC emission, and stops the emission, and when a signal to be transmitted to optical radio master equipment in the emission stopped state, restarts the DC emission. The transmission source address of a terminal 4 is compared with a transmitted destination address from the master set, and when both the addresses coincide with each other, the start of transmission from the terminal 4 is estimated and the supply of a driving current to a light emission means is restarted. When the DC emission is restarted, the DC emission is continued for a fixed period up to the stable reception of DC emitted light to the master set and then the transmission of the signal to the master set is restarted by burst emission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wireless slave device of a half-duplex optical wireless communication system for performing half-duplex optical wireless communication between an optical wireless master device and a plurality of optical wireless slave devices. In particular, the present invention relates to an optical wireless slave device which emits DC light at the midpoint level of burst emission amplitude when there is no signal to be transmitted to the optical wireless master device.

[0002]

2. Description of the Related Art Conventionally, a plurality of information processing devices such as personal computers have been connected to each other to form a LAN (Local
In the case of constructing an Area Network), those information processing devices are often connected by wires such as coaxial cables and optical cables. Wired connection is advantageous in that there are few data errors due to external noise because it can be connected securely from the device side, but wiring work is complicated and construction is required every time the layout is changed. There is.

In recent years, there has been an increasing demand for data transmission by connecting personal computers such as laptops, books, palmtops, and portable information processing devices such as electronic notebooks to each other. On the other hand, these portable information processing devices are originally intended to be carried around and used, and it is extremely rare that they are carried around while being connected by wire. For this reason,
When these portable information processing devices are connected to each other for data transmission, the connector is removed and inserted each time the device is moved, and such connection work is very troublesome. In addition, the connector may be repeatedly inserted and removed, and mechanical damage to the connection portion such as the connector may occur.

From the above, when data is transmitted and received between various information processing devices, not limited to the stationary type and the portable type, all or part of the transmission path is made wireless to reduce wired connection. There is a demand to want. Here, as a method of wireless transmission, there are a method using radio waves as a transmission medium and a method using light as a transmission medium. High-speed data transmission can be realized using either radio wave or optical transmission media, but there are legal restrictions on radio waves, and due to issues such as securing confidentiality, legal restrictions are imposed. Wireless transmission using light as a transmission medium that is easy to secure confidentiality is advantageous.

The Ethernet (registered trademark) LAN, which has the highest penetration rate among wired LANs, has, for example, 10 Mbps.
Since it has a transmission rate of 10 Mbps, it is desirable to have a transmission rate of at least 10 Mbps even in a wireless transmission path. Therefore, the applicant of the present application discloses in Japanese Patent Application Laid-Open No. 8-56198 "a method and apparatus for canceling return light of optical wireless communication" which uses light as a transmission medium and realizes a transmission speed of 10 Mbps. There is. The technology described in this publication realizes full-duplex communication by optical wireless communication between a ceiling-mounted master unit and a slave unit installed in a room. A method is adopted in which the adverse effect due to the reflected light can be removed by subtracting the transmission signal from.

That is, in the optical wireless transmission, light is transmitted to and received from the free space. Therefore, for example, an object located near the device of the other party transmits the light transmitted by itself. Since there is a problem that the signal light is input to the light receiving unit due to reflection or the like, and the communication signal from the other party cannot be accurately taken out, the technique described in the above publication has a problem that a part of the transmission signal is transmitted. Is branched, and the level and phase of this signal are adjusted and added to the received signal to cancel the signal due to the return light.

On the other hand, in recent years, it has been desired to increase the transmission speed, and even in the above-mentioned optical wireless communication system, the transmission speed is required to be further increased. However, considering the optical wireless communication in which the transmission speed is 100 Mbps, for example, the optical signal needs to be converted to 4B / 5B.
It becomes a transmission signal of 5 Mbps, and considering this signal in terms of phase, the 1-bit length is 8 ns, and the time that light travels 1 m is 3.3 ns.
Therefore, if the reflection path differs by 1 m (50 cm difference in distance to the reflecting object), 360 × 3.3 / 8 = 14
The difference is 8.5 degrees. In other words, in order to cancel the reflected light whose phase shifts greatly depending on the distance to such a reflector, not only the amplitude adjustment but also the phase that changes drastically must be adjusted sequentially, and an extremely complicated circuit is required. Becomes Furthermore, even if these methods are fully utilized, the cancellation can only be expected to improve accuracy within a limited range. Therefore, in order to realize a 1: N optical wireless communication device with high-speed transmission such as 100 Mbps, the half-duplex communication system is wise rather than the full-duplex communication system.

Therefore, the applicant of the present invention has proposed an optical wireless communication system of a half-duplex communication system which realizes a transmission rate of 100 Mbps in Japanese Patent Application No. 2000-237286, which is not publicly known. In this method, the master unit notifies the slave unit under its control of the optical line usage status as an optical line availability notification signal, and the slave unit detects this signal and applies for transmission permission with the master unit for each frame transmission. By performing processing (such as ID exchange) and obtaining the transmission permission from the base unit, the handset starts transmission to the base unit, so that the problem of reflected light described above is avoided by so-called half-duplex communication. .

However, in this system, the slave unit transmits various data such as a frame or a transmission request signal exchanged between the master units for optical transmission as described above (burst emission) in data units. It will be. At this time, if the burst light emission of the slave unit is a burst including a DC component that does not emit when the slave unit does not send a frame or a transmission request signal as shown in FIG. 9, the master unit receiving this signal, Due to the influence of a high-pass filter (HPF) provided in the receiving circuit, the received signal has a swell as shown in FIG. 10, and it becomes difficult to receive a stable signal. Therefore, in order to avoid such a situation, in the half-duplex optical wireless device as described above, the direct current component as shown in FIG. 11 is eliminated, that is, the slave unit bursts when no frame or transmission request signal is transmitted. It is desirable to emit DC light at the midpoint level = V1 / 2.

Referring to FIGS. 12 (A) and 12 (B), a slave unit in a half-duplex optical wireless communication system for carrying out a transmission procedure for each frame for transmission from the slave unit to the master unit will be described below. Also, a frame transmission / reception timing image between the parent device will be described. In the optical wireless communication system described below, it is assumed that the master unit is connected to another system via a network trunk line by wire and the slave unit is connected to a terminal such as a personal computer by wire. The master unit also includes a trunk-side transmitter that transmits signals to the network trunk line, a trunk-side receiver that receives signals from the network trunk line, a light-emitting unit that transmits optical signals to the slave units, and optical signals from the slave units. The slave unit has a light receiving unit for receiving signals, the light receiving unit for receiving the optical signal from the master unit, the light emitting unit for transmitting the optical signal to the master unit, and the terminal side transmitting unit for transmitting the signal to the terminal. And a terminal-side receiving unit that receives a signal from the terminal.

12 (A) and 12 (B) respectively show the case where the frame unit signal transmitted from the slave unit is transmitted only to the trunk side by the master unit (not returned to the optical side). 2 shows the timing of transmitting a frame signal to and the optical burst signal transmitted and emitted by the slave unit at that time.
It should be noted that there are not many practical examples of using half-duplex optical communication in an optical wireless communication system with a transmission rate of 100 Mbps, but FIG. 12 shows signals expected to be adopted when performing half-duplex optical communication. It shows the transmission / reception timing of, and here is the timing when the child device and the parent device have the minimum required memory, and of course, if a large capacity memory is installed, the timing will be different, The basic processing such as the transmission permission application procedure exchanged between the child device and the parent device is included in that category, and will be omitted here to avoid complexity of the description.

First, at the transmission / reception timing shown in FIG. 12 (A), when the frame F1 generated by the terminal is transmitted from the slave unit to the master unit, Tl in the figure indicates that the optical line is vacant from the master unit. When the optical line idle signal EP is optically transmitted, the slave unit that detects (receives) the optically transmitted optical line idle signal EP indicates to the master unit in the figure when it wants to use the optical line. The optical preamble signal (optical P) is added to the optical line transmission request signal RQ for requesting the use of the optical line as in T2, and the optical transmission is performed. When the master unit receives this optical line transmission request signal RQ, when the optical line can be used, the optical line transmission permission signal AK for permitting the use of the optical line to the slave unit as in T3 in the figure. And an optical preamble (optical P) is added to the optical transmission.

Upon receiving the optical line transmission permission signal AK from the master unit, the slave unit optically transmits the frame F1 received from the terminal to the master unit as an optical preamble signal (optical P) and a frame F1 as indicated by T4 in the figure. To do. The parent device wire-transmits the frame F1 sent from the child device to the network trunk line. The operation in the case of frame F2 is similar to the operation in frame F1.

In FIG. 12, the frame received from the terminal is sent from the child device to the parent device, and further sent from the parent device to the network trunk line. However, the opposite, that is, the frame received from the network trunk line is sent to the parent machine. When sending from a mobile device to a mobile device, and from the mobile device to a terminal, the transmission request and permission signal transmission procedure shown here is not taken. The preamble is added and sent to the slave unit side, and the slave unit receives this and sends it to the terminal.

Here, when the slave unit realizes the transmission as shown in FIG. 12A, the optical burst signal as shown in FIG. 12B is obtained, and the burst signal does not include a DC component. Therefore, when there is no transmission data, DC light emission is performed at the burst midpoint level (reference DC level) = V1 / 2, and when transmitting data, this DC light emission level = V1 /
Data transmission is realized by oscillating the light emission level = 0 to V1 up and down centering around 2.

As described above with reference to FIG. 12, according to the half-duplex optical communication, when the slave unit optically transmits the frame received from the terminal to the master unit, the slave unit uses the optical signal from the master unit. Detect a line idle signal, send an optical line transmission request signal to the base unit, receive an optical line transmission permission signal for it from the base unit, and then transmit the frame received from the terminal to the base unit. Therefore, it is considered that the light emission is a method using a midpoint burst signal excluding the DC component.

[0017]

However, in the above-mentioned example of half-duplex optical communication, since a plurality of slave units are connected to the master unit by an optical line, when the number of slave units increases There is a problem that the DC light emission when there is no signal is accumulated, the reception level of the base unit is saturated, and the data transmitted from the handset cannot be received correctly (problem 1). Also, regarding each slave unit, if the drive current is continuously applied to the light emitting element to transmit the midpoint burst signal even when the terminal rarely communicates, a problem of life and power consumption of the light emitting element occurs. Do (Problem 2).

The present invention has been made in view of the above-mentioned problem 1, and provides an optical wireless slave device of a half-duplex optical wireless communication system in which a larger number of slave devices can be arranged under the master device. The first purpose is to do so. The present invention is also made in view of the above-mentioned problem 2, and more child devices can be arranged under the control of the parent device, and the life of the light emitting element is lengthened to reduce power consumption. A second object of the present invention is to provide an optical wireless slave device of a half-duplex optical wireless communication system capable of performing the above.

[0019]

To achieve the first object, the present invention interrupts DC light emission and stops light emission when there is no signal to be transmitted to the optical wireless master device for a predetermined time. The DC light emission is restarted when a signal to be transmitted to the optical wireless master device is generated in the light emission stopped state.

That is, according to the present invention, in the optical wireless slave device of the half-duplex optical wireless communication system for performing half-duplex optical wireless communication between the optical wireless master device and a plurality of optical wireless slave devices, A signal transmitted from the optical wireless slave device to the optical wireless master device is transmitted by burst light emission, and when there is no signal to be transmitted, DC light emission is performed at the midpoint level of the burst light emission amplitude to generate a DC signal component. Means for performing signalless transmission that does not include stable reproduction and for a predetermined time,
Means for interrupting the DC light emission when there is no signal to be transmitted to the optical wireless master device and restarting the DC light emission when the signal for transmission is generated. An optical wireless slave device for a dual optical wireless communication system is provided.

In order to achieve the second object, the present invention shuts off the drive current of the light emitting means for emitting DC light when there is no signal to be transmitted to the optical wireless master device for a predetermined time. , Compare the source address in the signal transmitted from the terminal to the optical wireless master device with the destination address in the signal received from the optical wireless master device, and if they match, the terminal will soon start transmitting. It is assumed that the driving current of the light emitting means is restarted.

That is, according to the present invention, in the optical wireless slave device of the half-duplex optical wireless communication system for performing half-duplex optical wireless communication between an optical wireless master device and a plurality of optical wireless slave devices, A signal transmitted from the optical wireless slave device to the optical wireless master device is transmitted by burst light emission, and when there is no signal to be transmitted, DC light emission is performed at the midpoint level of the burst light emission amplitude to generate a DC signal component. Means for performing signalless transmission that does not include stable reproduction and for a predetermined time,
When there is no signal to be transmitted to the optical wireless master device, the drive current of the light emitting means for emitting the DC light is shut off, and the signal is transmitted from the terminal connected to the optical wireless slave device to the optical wireless master device. The transmission source address in the signal and the transmission destination address in the signal received by the terminal from the optical wireless master device are compared, and if they match, it is assumed that the terminal will soon start transmission and the drive current of the light emitting means. An optical wireless slave device of a half-duplex optical wireless communication system is provided.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of a main part of an optical wireless communication system as a first embodiment of the present invention. This optical wireless system uses Ethernet (registered trademark) (Ethern) that transmits and receives data by frame (packet) transmission.
This is a system connected to a network trunk line (hereinafter simply referred to as trunk line) 2 such as et (R)), and as shown in FIG. 1, the trunk line 2 and a terminal (for example, a terminal 4 (4a, composed of a personal computer, etc., 4b, 4c)
Optical wireless communication device 1 as a base unit (hereinafter referred to as base unit 1)
And an optical wireless communication device 3 as a slave (hereinafter, slave 3 (3
a), 3b, 3c)), and is a system for connection using half-duplex optical communication. In addition to the personal computer, the terminal 4 also includes a repeater such as a network interface card (NIC) or a hub (HUB).

FIG. 2 shows the frame F1 generated by the terminal 4 in the optical wireless communication system of FIG.
The basic signal transmission / reception timing in the case of transmitting to the network trunk line 2 and further to the network trunk line 2 is shown. In FIG. 2A, when the frame F1 generated by the terminal 4 is transmitted from the handset 3 to the base unit 1, first, the base unit 1 notifies the optical line availability indicating an optical line availability as shown by T1 in the figure. When the signal EP is optically transmitted, the optically transmitted optical line idle notification signal EP
When the slave unit 3 that has detected is wanting to use the optical line,
The optical preamble (optical P) is added to the optical line transmission request signal RQ for requesting the use of the optical line, and the optical transmission is performed to the master unit 1 as indicated by T2 in the figure.

Upon receiving the optical line transmission request signal RQ, the master unit 1 allows the slave unit 3 to use the optical line when the optical trunk line is available, as shown by T3 in the figure. An optical preamble (optical P) is added to the optical line transmission permission signal AK, the optical transmission is performed, and a certain period of time is waited for the frame F1 to be transmitted from the slave unit 3. When the handset 3 receives the optical line transmission permission signal AK from the base unit 1 within a certain time, the frame F1 received from the terminal is added with an optical preamble (light P) as shown by T4 in the figure to form the frame F1. Optically transmits to the master unit 1. When the handset 3 receives the frame F1 from the terminal 4 and the signalless state from the terminal 4 elapses for a certain period of time, the handset 3 notifies the optical line idle notification signal EP from the base unit 1 that the optical line is idle. After checking, the light emitting unit is stopped as shown in FIG.

Thereafter, the handset 3 sends a frame F2 from the terminal 4.
When the optical line is vacant, the optical line idle notification signal EP from the base unit 1 is confirmed that the optical line is vacant, and the light emitting unit starts light emission. In the example here, assuming that the handset 3 does not have a storage device that can completely hold the frame F2 from the terminal 4, the frame F2 is temporarily suppressed by the wired line suppression signal DY, and The transmission from 4 is stopped. The handset 3 exchanges a transmission procedure with the base unit 1 for the frame F3 received after the receiving unit of the base unit 1 has stabilized after a lapse of a certain time from the restart of light emission as in the case of the previous frame F1. , Optical transmission to the base unit 1.

FIG. 3 shows an example of a concrete configuration of the base unit 1,
The master unit 1 is controlled using the optical line transmission application from the slave unit 3 or the optical line transmission permission signal from the master unit 1 in response to the optical line availability notification signal from the master unit 1 as shown in FIG. The received frame is transmitted and a plurality of frames transmitted subsequent to the frame are received. In the master unit 1 shown in FIG. 3, the control unit 13 controls the entire operation of the master unit 1, and controls communication with the network trunk line 2 and half-duplex optical communication control with the slave unit 3. To do.

In addition, the master unit 1 has a structure for performing optical wireless communication with the slave unit 3 by outputting an optical signal in a wide range and transmitting each signal as an optical signal. It has a light emitting part) 19 and an optical line receiving part (light receiving part) 11 which receives light from a wide range and receives an optical signal as an electrical digital signal. The optical signal received by the optical line receiving unit 11 is input to the optical line frame receiving unit 8, the optical line frame detecting unit 9, and the optical line transmission request signal detecting unit 10 as an electric digital signal.

The optical line frame receiving unit 8 secures a frame to be transmitted to the main line 2 up to the transmission timing to the main line 2 according to the detection result of the optical line frame detecting unit 9 of the signal input from the optical line receiving unit 11, and controls it. It outputs to the wired output signal switching unit 6 under the control of the unit 13. The optical line frame detector 9 detects a frame from the input signal from the optical line receiver 11 and instructs the optical line frame receiver 8 to receive the frame. The optical line transmission application signal detector 10 is the optical line receiver 1
From the signal input from 1, the optical line transmission request signal sent from any slave unit 3 is detected and transmitted to the control unit 13, and the information of the detected transmission request signal (from which slave unit 3 (For example, an ID indicating whether it is an application) is transmitted to the optical line transmission permission signal detection unit 37.

The optical line transmission permission signal detection section 37 uses the application information (ID, etc.) detected and extracted by the optical line transmission application signal detection section 10 to transmit the optical line to the slave unit 3 which has transmitted the transmission application signal. The permission signal is transmitted to the optical transmission signal switching unit 18 according to the instruction of the control unit 13. The suppression pseudo signal generator 7 on the wired line side generates a suppression pseudo signal when it is necessary to suppress the signal from the trunk line 2 according to an instruction from the controller 13, and supplies the suppression pseudo signal to the wired output signal switching unit 6. To send. The wired output signal switching unit 6 receives the frame from the optical line frame receiving unit 8 and the suppression pseudo signal from the suppression pseudo signal generating unit 7, and appropriately switches each signal according to the instruction of the control unit 13 to appropriately switch the signals. Send to. The wired line transmission unit 5 outputs the signal from the wired output signal switching unit 6 to the trunk line 2 as a trunk line output signal.

The wired line receiving unit 14 receives the data from the trunk line 2 and sends the received data to the wired line frame detection unit 15 and the optical line transmission timing delay unit 16.
The wired line frame detection unit 15 detects a frame from the received data sent from the wired line reception unit 14, transmits the detection result to the control unit 13, and sends the frame detection result to the optical line transmission timing delay unit 16. Send.
The optical line transmission timing delay unit 16 is the wired line reception unit 14
Based on the frame detection result of the wired line frame detection unit 15 from the signal sent from the received frame, the received frame is made to stand by in a temporary storage device such as a FIFO, and the waiting frame is instructed by the control unit 13 at the optical line transmission timing. Then, the signal is transmitted to the optical transmission signal switching unit 18.

According to an instruction from the control unit 13, the optical preamble generation unit 17 generates a preamble signal to be added as a synchronization signal before the frame when the frame is optically transmitted, and transmits it to the optical transmission signal switching unit 18. According to the instruction from the control unit 13, the optical line idle notification signal generation unit 12 generates an optical line idle notification signal for notifying the slave unit 3 under the optical line that the optical line is available, and transmits the optical signal. Signal switching unit 18
Send to. The optical transmission signal switching unit 18 includes an optical line transmission permission signal from the optical line transmission permission signal detection unit 37, an optical line availability notification signal from the optical line availability notification signal generation unit 12, an optical preamble from the optical preamble generation unit 17, and Each data of the frame from the optical line transmission timing delay unit 16 is switched according to an appropriate instruction of the control unit 13 at any time, and is transmitted to the optical line transmission unit 19. The optical line transmission unit 19 transmits the data appropriately switched and output by the optical transmission signal switching unit 18 to the optical line as an optical signal.

FIG. 4 shows an example of a concrete structure of the slave unit 3,
When transmitting the transmission frame from the terminal 4 to the master unit 1, the slave unit 3 exchanges a transmission request and a transmission permission signal with the master unit 1 when transmitting the transmission frame from the terminal 4 to the terminal 4 as described above. If the frame is not transmitted from the terminal 4 for a certain period of time and the no-signal state continues in the wired receiving unit, the slave unit 3 stops emitting light, and then the frame is transmitted. When the frame is sent from the terminal 4, the light emission is started again.

In the child device 3 shown in FIG. 4, the control unit 2
The control unit 7 controls the entire operation of the slave unit 3 and controls communication with the terminal 4 and half-duplex optical communication with the master unit 1. Further, the handset 3 outputs light in a narrow range as a configuration for performing wireless radio communication with the base unit 1,
Optical line transmitter 20 for transmitting each signal as an optical signal
And an optical line receiving unit 28 that receives light from the base unit 1 and receives an optical signal as an electrical digital signal.

The wired line receiving unit 26 receives the signal from the terminal 4 and sends the received data to the optical line transmission timing delay unit 24, the wired line frame detecting unit 25 and the wired line no-signal time measuring unit 36. Wired line no-signal time measuring unit 36
Is received by the wired line receiving unit 26, and after receiving the frame detected by the wired line frame detecting unit 25,
It measures while the signal from the wired line is in a no signal state (frame does not come), and sends the result to the control unit 27. The wired line frame detecting unit 25 is a wired line receiving unit 26.
The frame transmitted to the optical line is detected from the signal received by the terminal 4, the detection result is sent to the control unit 27, and the detection result is similarly sent to the optical line transmission timing delay unit 24.
Send to.

The optical line transmission timing delay unit 24 FIFO-receives the received frame from the signal received by the wired line receiving unit 26 according to the detection result of the wired line frame detecting unit 25.
A temporary storage device such as the above is made to stand by, and this waiting frame is transmitted to the optical line output signal switching section 21 according to the instruction of the control section 27. The optical line transmission request signal generation unit 23 generates an optical line transmission request signal when a frame is transmitted from the terminal 4 and transmission permission from the base unit 1 to the optical line is required in accordance with an instruction from the control unit 27. An optical line transmission request signal is transmitted to the optical line output signal switching unit 21. In response to an instruction from the control unit 27, the optical preamble generation unit 22 generates a preamble as a synchronization signal at the time of reception of the master unit 1 before optical transmission of the frame, and transmits this to the optical line output signal switching unit 21.

The optical line output signal switching unit 21 includes a frame from the optical line transmission timing delay unit 24, an optical line transmission application signal from the optical line transmission application signal generation unit 23, and an optical preamble from the optical preamble generation unit 22. The signals are appropriately followed by appropriate instructions from the control unit 27, and each signal is switched and transmitted to the optical line transmission unit (light emitting unit) 20. The optical line transmission unit 20 includes a light emitting unit for optical transmission, transmits each signal sent from the optical line output signal switching unit 21 to the master device 1 as an optical signal, and emits light under the control of the control unit 27. Also, the stop of light emission can be controlled.

The optical line receiving unit (light receiving unit) 28 receives the optical signal sent from the master unit 1, and outputs an optical line idle notification signal detecting unit 30 and an optical line transmission permission signal detecting unit 31 as electric digital signals. , To the optical line frame detection unit 29 and the wired line transmission timing delay unit 32. The optical line availability notification signal detection unit 30 detects the optical line availability notification signal that the base unit 1 is emitting to notify the availability of the optical line from the received signal sent from the optical line reception unit 28, and the detection result. To the control unit 27. The optical line transmission permission signal detection unit 31 detects an optical line transmission permission signal for permitting the master unit 1 to permit the slave unit 3 to transmit a frame to the optical line from the received signal transmitted from the optical line reception unit 28. Then, the detection result is sent to the control unit 27.
Send to.

The optical line frame detection unit 29 detects the optical transmission frame transmitted by the base unit 1 from the received signal sent from the optical line reception unit 28, sends the detection result to the control unit 27, and the wired line transmission timing. Send to the delay unit 32,
Instruct to pause the frame. The wired line transmission timing delay unit 32 causes the detected frame from the received signal sent from the optical line reception unit 28 to temporarily wait in a temporary storage device such as a FIFO according to the frame detection result of the optical line frame detection unit 29. The standby frame is transmitted to the wired output signal switching unit 34 according to the transmission instruction to the terminal 4 of the control unit 27.

The suppression pseudo signal generator 33 on the wired line side
In accordance with an appropriate instruction from the control unit 27, when it is necessary to suppress transmission from the terminal 4 connected by wire, a suppression pseudo signal is generated and the suppression pseudo signal is sent to the wired output signal switching unit 34. The wired output signal switching unit 34 receives the frame signal from the wired line transmission timing delay unit 32 and the suppression pseudo signal from the suppression pseudo signal generation unit 33, and according to an appropriate instruction from the control unit 27, these frame signals The suppression pseudo signal is switched at any time and transmitted to the wired line transmission unit 35. The wired line transmission unit 35 transmits the signal sent from the wired output signal switching unit 34 to the terminal side wired line.

Next, a description will be given of the flow of processing when the communication procedure as described in the transmission / reception timing of FIG. 2 is realized in the master unit 1 having the configuration of FIG. 3 and the slave unit 3 having the configuration of FIG. . First, FIG. 5 shows a flow of processing in the base unit 1 (mainly a control unit) until the base unit 1 receives a frame transmitted via the network trunk line 2 and transmits this frame to the subordinate unit 3 under the control. 13 shows the flow of control operation 13). Figure 5
First, the control unit 13 of the parent device 1 operates in step S1.
As the processing of the above, it is monitored whether or not optical communication is performed with the handset 3, and when the optical line is not used, the optical line idle notification signal is optically transmitted to the subordinate handset 3 under the control. . next,
In step S2, the signal from the trunk line 2 is monitored, and if the frame is not sent from the trunk line 2, the optical transmission control state is waiting for the frame from the trunk line, and when the frame is received from the trunk line 2, the next step S3. Move to.

In step S3, it is checked by the state of the optical line whether the frame received from the trunk line 2 can be output to the optical line. If the optical line is used by the slave unit 3 or the like, the process proceeds to step S8 to transmit the suppression pseudo signal to the trunk line 2, then in step S9, it is confirmed that the frame transmission from the trunk line 2 is stopped, and then the step The suppression pseudo signal is stopped in S10, and then the process returns to step S2 and waits until a frame from the trunk line 2 is received.

If the optical line is vacant in step S3, the process proceeds to step S4, and the frame from the trunk line 2 is made to wait for the optical line transmission timing to the temporary storage device such as FIFO until the optical line transmission timing, and in the next step S5. The optical line idle notification signal (command) that was sent to 3 is stopped, then in step S6, before transmitting the frame, the handset transmits an optical preamble for synchronizing the reception, and subsequently in step S5. The frame temporarily held is optically transmitted in step S7. When the transmission of the frame is completed, an optical line idle notification signal is sent to the slave unit in step S43 to notify that the optical line is idle, and then the process returns to step S2 to wait for frame reception from the trunk line 2.

Next, in FIG. 6, there is an optical transmission application from the subordinate unit 3 under its control, the parent unit 1 permits it, and the parent unit 1 receives the frame optically transmitted from the subunit 3 and sent, The flow of processing in the master device 1 (mainly the flow of control operation of the control unit 13) until this frame is transmitted to the network trunk line 2 is shown. In FIG. 6, the control unit 13 of the base unit 1 first determines whether or not there is an optical line transmission application signal from the handset unit 3 based on the detection result of the optical line transmission application signal detection unit 10 as the process of step S11. If there is a transmission request signal from the handset 3, the process proceeds to step S12 to stop the optical line idle notification signal, and then proceeds to step S13 to identify the handset of the transmission signal received from the handset 3. An optical line transmission permission signal incorporating information (such as ID) is added to this with an optical preamble and transmitted to the optical line.

When the transmission permission signal is transmitted, step S14
In the case of waiting for the frame optical transmission from the handset 3, when no frame arrives within a certain period of time, it is timed out in step S16, and in the following step S17, it is confirmed that the frame from the trunk line 2 is not transmitted, In order to open the optical line again to the slave unit 3 under its control, an optical line idle notification signal (command) is transmitted in step S18. If step S
If the frame is coming from the trunk line 2 at 17, the optical preamble is added and optical transmission is performed at step S19. Here, the optical transmission of the frame from the trunk line 2 is performed in step S1.
7 and step S19, the optical transmission flow of the frame from the trunk line 2 is shown in FIG.
It operates according to the flow of. When the frame can be optically received from the handset 3 in step S14, the received frame is transmitted to the trunk line 2 in step S15 in consideration of the timing.

Next, the operation of the slave unit 3 for realizing the communication described with reference to the transmission timing of FIG. 2 will be described. First, FIG. 7 shows the flow of processing in the handset 3 until the handset 3 receives the frame sent from the base unit 1 and transmits this frame to the terminal 4 connected by a wired line (mainly control The flow of the control operation of the unit 27) is shown.

In FIG. 7, first, in step S20, it is monitored whether or not a frame is transmitted from the base unit 1, and if there is an optical transmission frame from the base unit 1, in step S21, a FIFO or the like is temporarily sent. The optically received frame is secured in the temporary storage device of No. 4, then, in step S22, it is confirmed whether or not the frame from the terminal 4 has come to the wired line, and if the frame is sent from the terminal 4, In step S25, a suppression pseudo signal is once sent to the wired side in order to suppress frame transmission from the terminal 4. If the wired line is vacant in step S22, if the suppression pseudo signal is being sent in step S23 at this time, it is stopped in this step, and in the next step S24, the frame held in step S21 is transferred to the wired line. It is sent out and sent to the terminal 4.

Next, FIG. 8 is a timing chart of FIG.
In the slave unit 3 having the above configuration, the flow of processing in the slave unit 3 (mainly of the control operation of the control unit 27 until the slave unit 3 transmits the frame transmitted from the terminal 4 to the master unit 1 through the optical line). Flow). In FIG. 8, first, step S
At 26, it is monitored whether there is a frame transmission from the terminal 4, and if a frame is transmitted, step S
At 33, it is determined whether the light emitting unit is in the midpoint light emission (DC light emission) state. If the light emitting unit is in the light emission stopped state, step S34.
At, the optical line idle notification signal from the base unit 1 is detected.

If the vacancy of the optical line can be confirmed, the middle point light emission of the light emitting unit is started in step S41, and step S41 is started.
At 37, the suppression pseudo signal is transmitted to the terminal side through the wired line, then at S38, the stop of the transmission from the terminal 4 is confirmed, then at step S39, the suppression pseudo signal to the terminal 4 is stopped, and then at step S26. Wait for the frame from the terminal again. If the light emitting unit emits the midpoint light in step S33, it is confirmed in step S40 whether or not a certain time has elapsed from when the light emitting unit starts to emit light until the receiving unit of the parent device 1 stabilizes. If the time required for the receiver of the base unit 1 to stabilize has not elapsed here, step S
In step 37, step S38 and step S39, the suppression pseudo signal is transmitted to the wired line to suppress the terminal 4 to stop the frame transmission, and then in step S26, the frame from the terminal 4 is waited again.

If it is confirmed in step S40 that the light emitting unit has begun to emit light and a predetermined time has passed,
In step S27, the frame being sent is temporarily held in a temporary storage device such as a FIFO until the transmission timing to the optical line. Next, in step S28, the vacancy of the optical line is detected by monitoring the optical line vacancy notification signal sent from the parent device 1 to determine whether the optical line is vacant. In this step S28, the optical line is not vacant and step S3
If the time-out occurs in 5, the suppression pseudo signal is transmitted to the wired line in steps S37, S38, and S39 to suppress the terminal 4 and stop frame transmission, and then in step S26, wait for a frame from the terminal 4 again. .

Here, when the optical line idle notification signal from the master unit is detected in step S28 and the optical line idle can be confirmed, the process proceeds to step S29, and the transmission to the optical line to the master unit 1 is performed. In order to request permission, an optical line transmission request signal with an optical preamble is optically transmitted to the master device 1. After sending the optical line transmission application, step S30
In step S37, if a transmission permission signal is returned from the master unit 1 for a certain period of time, and if the transmission permission signal is not obtained from the master unit 1 and time-out occurs in step S36, steps S37, S38, Step S3
In step 9, a suppression pseudo signal is sent to the wired line to suppress the terminal 4 to stop frame transmission, and then step S2
At 6 again, the frame from the terminal 4 is waited for again. Step S30
In step S31, when the optical line transmission permission signal is obtained from the master unit 1, the master unit 1 optically transmits an optical preamble as a synchronization signal when the master unit 1 optically receives a frame, and subsequently in step S32. In step S27, the frame from the terminal 4 that has been temporarily waiting is optically transmitted.

If no frame is received from the terminal 4 side in step S26, the elapsed time of the signalless state on the wired side after the frame is not sent from the terminal 4 side is measured in step S42. , Determine if this state has passed a certain time. If the fixed time has not passed since the frame did not come from the wired side, the process returns to step S26 and waits for the frame reception from the terminal 4. If, in step S42, the elapsed time of the no-signal state of the wired line has passed a certain time, the idle signal of the optical line is monitored in step S43 to confirm that the optical line is idle, If the optical line is not available, the process returns to step S26 to monitor the reception state of the wired line. If it is confirmed in step S43 that the optical line is available, the light emission of the light emitting unit is stopped in step S44, and then the transmission from the wired line is monitored in step S26.

<Second Embodiment> By the way, in an actual network use environment, a terminal 4 existing in a certain area is used.
In many cases, communication is performed to check the connection status of the device and the address, especially when the signal data sent from the optical line side is the data to the terminal 4 connected to a certain handset 3. The response from the terminal 4 is often sent to the optical line side immediately after the end. Therefore, if it is possible to determine whether or not the destination of the signal data received from the optical line side of the handset 3 is the signal data to the terminal 4 connected to itself,
Next, the signal data sent from the terminal 4 can be quickly output to the optical line. The communication protocol described below is, for example, the TCP / IP method. In this method, a packet sent from a transmission source to a transmission destination has a transmission destination address, a transmission source address, and communication data.

FIG. 13 shows the sequence of the second embodiment. When the handset 3 receives the signal of the frame F1 from the optical line, it confirms the destination address in the received data and connects to itself. It shows a case where an address for the terminal 4 that has been deleted is detected. In preparation for a signal from the terminal 4 during the reception of the frame F1, the drive current level of the transmitting means is quickly raised to the midpoint level of the light emission drive current, so that the F2 from the terminal 4 as shown in FIG. It is possible to send the optical line transmission request signal RQ at the same time as receiving the signal from the terminal 4 without sending a suppression signal to the signal.

FIG. 14 shows the structure of the slave unit 3 according to the second embodiment, which is different from the structure shown in FIG. 4 in that the MAC / IP detecting means 40 and 42 are provided on the wired side and the optical line side, respectively.
The MAC / IP storage means 41 and the comparison means 43 are added. The MAC / IP detecting means 40 always observes the signal input from the wired line receiving unit 26 as shown on the right side of FIG. 15 to detect the sender (S), that is, the MAC address and IP address of the terminal 4, and If there is another address, it is stored in the MAC / IP storage means 41. On the other hand, MAC
The / IP detecting means 42 observes the signal input from the signal receiving section 28 from the optical line as shown on the left side of FIG. 15, detects the MAC address and IP address of the destination (D), and causes the comparing means 43 to perform detection. Tell.

The comparison means 43 is the MAC / IP storage means 41.
The address of the terminal 4 stored in the above is compared with the destination address detected by the MAC / IP detecting means 42,
When they match, the control unit 27 is notified. The control unit 27 controls whether or not to supply a current for maintaining the midpoint level to the optical line transmission unit 20, and if the above-mentioned notification of coincidence is received while the current is cut off, the optical line transmission is promptly performed. Part 2
The drive current of 0 is raised to the midpoint level.

FIG. 16 shows the processing of the child device 3 of the second embodiment, and step S is performed for the flowchart shown in FIG.
45, S46, and S47 are added. If the frame from the terminal 4 side is not received in step S26, the presence or absence of the frame signal from the optical line is detected in step S45. If the frame from the optical line is present, this received frame is detected in the next step S46. It is determined whether or not the MAC address / IP address existing in the MAC address / IP address has been sent from the wired line (terminal 4) side, and here it is determined to be equal to the contents of the MAC / IP storage means 41 shown in FIG. In this case, the light emission at the midpoint level is restarted in step S47.

Here, FIG. 17 shows the details of the determination in step S46. First, in step S50, it is determined whether the destination MAC (D-MAC) address from the optical line matches the source MAC (S-MAC) address that has been sent from the wired line (terminal 4 side), If they match, the process proceeds to step S54. On the other hand, even when the MAC address does not match in step S50, the destination MAC address is the multicast address (Yes in step S51) and the destination IP address is the broadcast address (Yes in step S52).
Terminal S may return a response, so step S
Proceed to 54. Even when the destination MAC address is the multicast address and the destination IP address is not the broadcast address in step S51 (No in step S52), the destination IP address matches the source IP address from the wired line. If so, step S5
Go to 4. If neither of the steps S51 and S53 applies, the process proceeds to step S42.

In step S54, if the LED drive current of the optical line transmission unit (light emitting unit) 20 is in the cutoff state, the drive current is returned to the midpoint drive in step S47, and the initial state shown in FIG. 16 is restored. If it was already midpoint driven,
In step S42, the elapsed time of the signalless state on the wired side after the frame is not sent from the terminal 4 side is measured, and it is determined whether this state has passed for a certain period of time. If a certain time has not passed since the frame did not come from the wired side, the process returns to the initial state shown in FIG. 16 and waits for the frame reception from the terminal in step S26.
If, in step S42, the elapsed time in the no-signal state of the wired line has passed a certain time, the idle notification signal of the optical line is monitored in step S43 to confirm that the optical line is idle. If the optical line is not available, the reception state of the wired line is monitored in step S26. If it is confirmed in step S43 that the optical line is available, the light emission of the light emitting unit 20 is stopped in step S44, and the transmission from the wired line is monitored in step S26.

[0060]

As described above, according to the present invention, the light emission is stopped when the child device does not need the optical transmission. Therefore, when a plurality of child devices exist under the parent device, It is possible to alleviate the problem that the reception level of the master unit falls into a saturated state due to the accumulation of the transmission standby light emission of the slave unit (mid-level light emission when there is no signal). : N optical wireless communication system can be realized.
Further, by minimizing the light emission of the slave unit, the power consumption can be suppressed, and the load on the terminal battery can be suppressed even when the slave unit is used in a battery-driven terminal such as a mobile terminal. Furthermore, since the light emission is performed only when necessary, the light emission time is effectively shortened, and the usage period (commercial life) of the light emitting element can be extended.

[Brief description of drawings]

FIG. 1 is a first half-duplex optical wireless communication system according to the present invention.
It is a block diagram which shows the embodiment of FIG.

FIG. 2 is a timing chart showing a timing when a frame is transmitted from the slave unit to the master unit of FIG. 1 and a waveform diagram showing a light emission signal of the slave unit.

FIG. 3 is a block diagram showing a configuration of a master unit shown in FIG.

FIG. 4 is a block diagram showing a configuration of a slave unit in FIG.

5 is a flowchart showing a schematic process of the master unit of FIG. 1 at the time of transmitting an optical line frame and transmitting an optical line idle notification signal.

FIG. 6 is a flowchart showing a schematic process when the master unit of FIG. 1 receives an optical line frame.

7 is a flowchart showing a schematic process of the slave unit of FIG. 1 at the time of receiving an optical line frame and at the time of wired transmission.

8 is a flowchart showing a schematic process of the slave unit of FIG. 1 when transmitting an optical line frame.

FIG. 9 is a waveform diagram showing a burst signal in which a DC component remains.

10 is a response waveform diagram of the burst signal of FIG. 9 after passing through the HPF.

FIG. 11 is a waveform diagram showing a burst signal from which a DC component has been removed.

FIG. 12 is a timing chart showing a timing when a frame is transmitted from a conventional slave unit to a master unit and a waveform diagram showing a light emission signal of the slave unit.

FIG. 13 is a timing chart showing a timing when a frame is transmitted from a child device to a parent device and a waveform diagram showing a light emission signal of the child device in the second embodiment.

FIG. 14 is a block diagram showing a configuration of a slave unit according to a second embodiment.

FIG. 15 is an explanatory diagram showing address comparison of the child device according to the second embodiment.

FIG. 16 is a flowchart showing an optical line frame transmission process of a slave unit according to the second embodiment.

FIG. 17 is a flowchart showing in detail the address comparison process of FIG.

[Explanation of symbols]

1 base unit 3 cordless handsets 4 terminals 13, 27 Control unit 20 Optical line transmitter (light emitter) 40, 42 MAC / IP detection means 41 MAC / IP storage means 43 Comparison means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) H04L 12/28 300 (72) Inventor Katsuo Okuaki 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Japan Victor Company of Japan In-house (72) Inventor Takeo Tsubooka 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company, Limited F-term (reference) 5K033 CA06 DA20 DB05 5K102 AA01 AA20 AA21 AB09 AL14 AL21 AL23 KA31 MA01 MB02 MC11

Claims (5)

[Claims] 1. An optical wireless master device of a half-duplex optical wireless communication system for performing half-duplex optical wireless communication between an optical wireless master device and a plurality of optical wireless slave devices. A signal to be transmitted from the optical wireless slave device side by burst emission, and when there is no signal to be transmitted, D is set at the midpoint level of the burst emission amplitude.
A means for performing signalless transmission that does not include a DC signal component and can be stably reproduced by emitting C light, and interrupts the DC light emission when there is no signal to be transmitted to the optical wireless master device for a predetermined time. And a unit that restarts the DC light emission when the signal to be transmitted is generated, the optical wireless slave device of the half-duplex optical wireless communication system. 2. The optical wireless master device of a half-duplex optical wireless communication system, which performs half-duplex optical wireless communication between an optical wireless master device and a plurality of optical wireless slave devices, A signal to be transmitted from the optical wireless slave device side by burst emission, and when there is no signal to be transmitted, D is set at the midpoint level of the burst emission amplitude.
A means for performing signalless transmission that does not include a DC signal component and can be stably reproduced by emitting C light, and emits the DC light when there is no signal to be transmitted to the optical wireless master device for a predetermined time. The drive current of the light emitting means is cut off, and the source address in the signal transmitted from the terminal connected to the optical wireless slave device to the optical wireless master device and the terminal received from the optical wireless master device. A half-duplex optical wireless communication system, which compares the destination addresses in the signals, and resumes the energization of the drive current of the light-emitting means assuming that the terminal will soon start transmission if they match. Optical wireless slave device. 3. When the DC light emission is restarted, the signal to be transmitted is transmitted by burst light emission after the DC wireless emission is continued until the optical wireless master device can stably receive the DC light emission. Claim 1 characterized by the above.
Or an optical wireless slave device of the half-duplex optical wireless communication system according to item 2. 4. The DC light emission is interrupted when there is no signal to be transmitted from the terminal connected to the optical wireless slave device to the optical wireless master device for a predetermined time, and when the data to be transmitted is generated. The DC light emission is restarted, the transmission data is temporarily stored in a storage device internally, and data transmission from the terminal is interrupted when the storage device does not have a capacity for storing the transmission data. An optical wireless slave device of the half-duplex optical wireless communication system according to claim 1. 5. When restarting the DC light emission, the DC light emission is restarted after detecting an optical line availability notification signal transmitted from the optical wireless master device. An optical wireless slave device of the half-duplex optical wireless communication system according to any one of Items 1 to 4.