JP2003258818A - Optical radio communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize efficient communication by preventing the collision of optical line transmission application signals between a plurality of sets of optical radio communication equipment on terminal sides in a one-to-N optical radio communication system. <P>SOLUTION: In optical radio communication equipment on a terminal side for performing semi-duplex optical communication with optical radio communication equipment connecting to a trunk network in order to realize communication between the trunk network and the terminal, a carrier sensing means 38 detects a free optical line notifying signal EP showing there is a free communication line from a signal received from the optical radio communication equipment on the trunk side, and a controlling means (transmission application enabled time determining means) 27 determines whether time has passed more than prescribed time from transmission timing at which the optical radio communication equipment on the trunk side transmitted the free optical line notifying signal EP. When it is determined that time has passed more than the prescribed time, an optical line transmission application signal RQ notifying that a frame from the terminal is transmitted to the optical radio communication equipment on the trunk side is prevented from being transmitted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in order to realize communication between a trunk network and a terminal, uses an optical wireless communication apparatus on the trunk side connected to the trunk network and an optical wireless communication apparatus on the terminal side connected to the terminal. The present invention relates to an optical wireless communication device on the terminal side in an optical wireless communication system configured to perform half-duplex optical communication between the optical wireless communication devices on the main line side and the terminal side, and particularly for one optical wireless communication device on the main line side. The present invention relates to a terminal-side optical wireless communication device in a 1: N optical wireless communication system in which a plurality (N) of terminal-side optical wireless communication devices perform half-duplex optical communication.

[0002]

2. Description of the Related Art Conventionally, a plurality of information processing devices such as personal computers are connected to each other to form a LAN (Local Area).
In the case of constructing a network (local area network), those information processing devices are often connected by a wire such as a coaxial cable or an optical cable. When the connection is made by wire, the connection between the devices can be surely made, which is advantageous in that the data error due to external noise is small. However, on the other hand, there is a problem that the wiring work is complicated and the work is required every time the layout is changed.

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. These portable information processing devices are devices intended to improve portability, and are extremely rare to carry and move while being connected by wire. In addition, when a wired connection is used, when these portable information processing devices are connected to each other for data transmission, the connector is removed and inserted for each movement, which is very troublesome. . Further, if the connector is frequently inserted and removed, there is a possibility that mechanical damage may occur to the connecting portion such as the connector.

From the above, not only the stationary type and the portable type but also when transmitting and receiving data between various information processing devices, all or part of the transmission path is made wireless and connected by wire. There is an increasing demand to reduce In wireless communication, there are a communication method using radio waves as a transmission medium and a communication method using light as a transmission medium. It is possible to realize high-speed data transmission using either of these radio waves or optical transmission media, but when radio waves are used, legal regulations (for example, available frequency band Since there is a problem that there is a regulation) and it is difficult to secure confidentiality, there is no legal regulation and wireless transmission using light as a transmission medium which is easy to secure confidentiality is more effective.

Further, since the Ethernet (R) LAN (Ethernet (R) LAN), which is the most popular wired LAN, has a transmission rate of, for example, 10 Mbps, a transmission rate of at least 10 Mbps is required even in a wireless transmission line. It is desirable to have. In this way, using light as the transmission medium,
As a technique for realizing a transmission rate of 10 Mbps, for example, "a return light canceling method for optical wireless communication and its apparatus" disclosed in Japanese Patent Laid-Open No. 8-56198 is known.

The technique disclosed in Japanese Patent Application Laid-Open No. 8-56198 realizes full-duplex optical communication by optical wireless communication between a master unit mounted on the ceiling and a slave unit installed in a room. In particular, with respect to the parent device, a method is adopted in which the transmission signal is subtracted from the reception signal to eliminate the adverse effect of reflected light. That is, in optical wireless transmission, light is transmitted to and received from free space. Therefore, the transmission signal light transmitted by itself is located near the communication partner device, for example. However, there is a problem in that it is reflected by an object and is input to the light receiving unit of the own device, and it becomes impossible to accurately extract the communication signal from the communication partner device. Therefore, in the technique described in Japanese Patent Laid-Open No. 8-56198, a part of the transmission signal is branched, and the level and phase of this signal are adjusted and added to the reception signal, so that the signal due to the returning light is generated. I'm trying to cancel.

On the other hand, in recent years, it has been desired to increase the transmission speed, and even in the above optical wireless communication system, the transmission speed is required to be further increased. However, considering optical wireless communication in which the transmission speed is 100 Mbps, for example, the signal becomes a 125 Mbps transmission signal due to the necessity of 4B / 5B conversion (4 bytes / 5 bytes conversion), and this signal is in terms of phase. Considering it, 1 bit length is 8n
The time for which light travels 1 m at s is 3.3 ns. From this, if the reflection paths are different by 1 m (a difference of 50 cm in distance to the reflecting object), 360 × (3.3 / 8) = 148.5.
The degree is also different. In other words, in order to cancel the reflected light whose phase greatly shifts depending on the distance to the reflector in this way, it is necessary to sequentially adjust not only the amplitude adjustment but also the phase that greatly changes, which is extremely complicated. A circuit is needed. Furthermore, even if these methods are used effectively, 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, it is prudent to use a half-duplex optical communication system instead of a full-duplex optical communication system.

From these things, the applicant of the present invention has already disclosed in Japanese Patent Application No. 2000-237286 that 100
An application has been filed for "optical wireless communication device and optical wireless communication system" for realizing Mbps transmission. In addition, this Japanese Patent Application 200
The technique described in 0-237286 has not been published at the time of filing the present invention and is not a known technique. In the technology described in this Japanese Patent Application No. 2000-237286, the master unit notifies the slave unit under its control as an optical line availability notification signal of the usage status of the optical line, and the slave unit detects this signal to detect the slave unit. Is a process for performing transmission permission application processing (ID exchange, etc.) with the master unit for each frame transmission, and the slave unit starts transmission to the master unit after obtaining transmission permission from the master unit. The problem of reflected light in the heavy-duty communication system is avoided.

That is, as shown in FIG. 2, when the optical line of the master unit 1 is vacant, the master unit 1 informs the slave unit 3 under the optical line availability notification signal EP. (ID
(LE burst) is transmitted to the child device 3. Cordless handset 3
Detects a notification signal sent from the parent device 1 using a carrier sense circuit, and if there is a frame F1 sent from the terminal 4 at this time, after receiving the optical line idle notification signal EP, The transmission request signal RQ is transmitted to the machine 1.
Then, after receiving the permission signal AK from the master device 1, the frame F1 received from the terminal 4 is transmitted to the master device 1. In addition, when the master unit 1 receives the frame F2 from the trunk line 2, it stops transmitting the optical line idle notification signal EP to the slave unit 3, and transmits the frame F2 received from the trunk line 2 to the slave unit 3. Send. With such a method, a half-duplex optical communication system by optical wireless of 1: N (master unit: slave unit) is realized.

[0010]

However, in the half-duplex optical communication system by optical wireless realized by the above method, the half-duplex optical transmission process (transmission application, which is performed when the slave unit transmits a frame to the master unit). Since transmission permission) and an optical preamble for synchronizing reception are required, the communication overhead becomes large and the communication performance is greatly affected. Therefore, it is necessary to avoid that the optical line idle notification signal EP (IDLE burst) sent from the master unit is as short as possible and its cycle becomes unnecessarily long.

In this case, if the optical line idle notification signal is detected after the reception synchronization is established, the communication performance is deteriorated, and therefore the detection is performed using the carrier sense circuit. However, in such an optical wireless half-duplex optical communication system, the distance between the slave unit and the master unit is not constant, and the slave units placed under the same master unit are about 1 to 8 m in length depending on the installation conditions. It is distributed in the area. Therefore, depending on the distance from the base unit,
Since the intensity (light intensity) of the light received by each slave unit from the master unit varies greatly, it is very difficult for each slave unit to stably detect the light reception signal at high speed without being affected by the amount of light intensity. The machine carrier sense will vary.

Therefore, the carrier sense of the slave unit may be delayed (longer) than necessary, and the slave unit may notify the master unit based on the optical line idle notification signal detected with the delay being longer than necessary. Even if the transmission request signal is transmitted by the above, the transmission request signal does not reach the master unit before the transmission request signal waiting time of the master unit, so it may happen that the transmission permission signal from the master unit cannot be obtained. Become. That is, at such a timing, the child device cannot obtain the transmission permission from the parent device, and further, when there are a plurality of child devices, a collision with the transmission request signal of another child device may occur. The performance of the entire half-duplex optical communication system by 1: N (base unit: handset) optical wireless is deteriorated.

In view of the above problems, the present invention has an object to realize efficient communication in an optical wireless communication system, and in particular, one optical wireless communication device on the trunk side has a plurality of ( In a 1: N optical wireless communication system in which the optical wireless communication devices on the terminal side (N units) communicate, the collision of optical line transmission request signals between the optical wireless communication devices on the terminal side is prevented and smooth. The purpose is to enable communication.

[0014]

In order to achieve the above object, according to the present invention, an optical wireless communication device on the terminal side delays an optical line availability notification signal from the optical wireless communication device on the trunk side by a predetermined time or more. If detected, this detection is invalidated and transmission application to the optical wireless communication device on the trunk side is prohibited.

That is, according to the present invention, in order to realize communication between a trunk network and a terminal, an optical wireless communication device on the trunk side connected to the trunk network and a terminal side connected to the terminal are connected. In an optical wireless communication system configured with an optical wireless communication device and performing half-duplex optical communication between the optical wireless communication devices on the trunk side and the terminal side,
An optical wireless communication device on the side of the terminal, from the terminal,
Terminal side receiving means for receiving a frame for transmitting to the trunk line network, optical line receiving means for receiving an optical signal from the optical wireless communication device on the trunk side, and the optical signal from the optical line communication means on the trunk side Carrier sense means for detecting an optical line idle notification signal indicating that the communication line between the optical wireless communication device and its own device is available, and the optical wireless communication device on the trunk side transmits the optical line idle notification signal From the transmission timing, the transmission application available time determining means for determining whether or not a predetermined time or more has elapsed, and when the transmission application available time determination means determines that the predetermined time or more has elapsed, the terminal To prohibit the transmission of the optical line transmission request signal for applying to the optical wireless communication means on the trunk side to the optical wireless communication means on the trunk side. And transmission control means for, optical wireless communication apparatus having is provided.

Further, according to the present invention, when the transmission control means controls the transmission of the frame, a suppression pseudo signal generating means for generating a suppression pseudo signal including an instruction to stop the transmission of the frame from the terminal. And on the terminal,
An optical wireless communication device is provided, comprising: a terminal-side transmitting unit that transmits the suppression pseudo signal.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical wireless communication apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of an optical wireless communication system including an optical wireless communication device of the present invention. The optical wireless communication system shown in FIG. 1 is an Ethernet (R) LAN that transmits and receives data by frame (packet) transmission.
Is a system connected to a trunk line network, such as a trunk line (network trunk line) 2, and a terminal 4 (terminal 4) realized by, for example, a personal computer.
a, the terminal 4b, and the terminal 4c), the optical wireless communication device 1 as a master unit (hereinafter referred to as the master unit 1) and the optical wireless communication device 3 as a slave unit (hereinafter, the slave unit 3 (slave unit) 3a, cordless handset 3
b, referred to as a slave unit 3c)), and is connected using half-duplex optical communication.

The terminal 4 includes, in addition to a personal computer, a network interface card (NIC) and a hub.
Also includes repeaters such as. In addition, in the present embodiment, a configuration in which the handset 3 and the terminal 4 are connected by a wired line will be described, but this connection is not limited to the wired line, and it is possible to connect by a wireless line.

FIG. 2 is a timing chart showing an embodiment of basic communication timing between the master unit connected to the trunk line and the slave unit connected to the terminal in the optical wireless communication system shown in FIG. It is a chart. In FIG. 2, the terminal 4
When the frame F1 generated in 1 is transmitted from the child device 3 to the parent device 1 (uplink), and the frame F2 sent from the trunk line 2 to the parent device 1 is transmitted to the terminal 4 via the child device 3. The basic timing for each of the transmission cases (downlink) is shown.

FIG. 2 shows the processing in each of the master unit 1, the trunk line 2, the slave unit 3, and the terminal 4 according to a time axis flowing from left to right. First, the master unit 1 transmits to the slave unit 3 an optical line idle notification signal EP that informs that the optical line is free, and the slave unit 3 sends the optical line idle notification signal EP from the parent unit 1 to the optical line idle notification signal EP. Detection is performed by performing carrier sense (carrier sense) (above, processing in the section indicated by "line idle" in FIG. 2).

When the handset 3 receives the frame F1 sent at the timing T2 from the terminal 4, when the carrier sense of the optical line availability notification signal EP from the handset 1 detected at the timing T1 is completed, the handset 3 1 at timing T3, optical line transmission request signal RQ requesting use of optical line
A signal to which an optical preamble (optical P) is added is optically transmitted. The handset 3 also receives the frame F1 from the terminal 4 as FI.
It is temporarily stored in a wired reception temporary storage device such as FO (First In First Out) so that it can be sent out when necessary (timing T5).

When the trunk line 2 is available, the master unit 1 which receives the optical line transmission request signal RQ from the slave unit 3
Transmits a signal obtained by adding an optical preamble (optical P) to the optical line transmission permission signal AK indicating the permission to use the optical line to the slave unit 3 at timing T4, and the frame F1 is transmitted from the slave unit 3. It will be in a waiting state waiting for a certain period of time.

When the slave unit 3 receives the optical line transmission permission signal AK from the master unit 1 within a certain time after transmitting the optical line transmission request signal RQ, the slave unit 3 receives the timing T from the master unit 1.
At 6, the signal in which the optical preamble (optical P) is added to the frame F1 received from the terminal 4 is optically transmitted. At this time,
The frame F1 from the terminal 4 is temporarily stored in the wired reception temporary storage device such as FIFO until the transmission application process is completed by the slave 3. Then, the parent device 1 that has received the frame F1 from the child device 3 transmits this frame F1 to the trunk line 2 at timing T7 (the above is the processing in the section indicated by “child device → parent device communication” in FIG. 2).

The master unit 1, which receives the frame F2 from the main line 2 at timing T9, sends the optical preamble (optical P) to the frame F2 at timing T10 with respect to the slave unit 3 corresponding to the transmission destination of the frame F2. Optically transmit the added signal. Then, the child device 3 which has received the frame F2
Transmits the frame F2 to the terminal 4 at timing T11 (the above is the process in the section indicated by “master unit → slave unit communication” in FIG. 2).

Here, in order to simplify the explanation,
When the master device 1 transmits the frame F1 to the trunk line 2 (timing T7) and when the slave device 3 transmits the frame F2 to the terminal 4 (timing T11), between the master device 1 and the trunk line 2 and the slave device 3 The case where there is no signal collision between the terminals 4 has been described, but when a signal collision occurs, the master unit 1 and the slave unit 3 perform the retransmission processing of the frame F1 or the frame F2, respectively. Preferably.
Therefore, both the master unit 1 and the slave unit 3 have a temporary storage device for resending processing, and the resending capability (possible number of times).
Depends on the capacity of the temporary storage device.

When the handset 3 receives the frame F1 from the terminal 4 and the transmission application to the base unit 1 is not accepted (transmission is impossible), a suppression pseudo signal is sent to the terminal 4 to The transmission of the frame F1 from 4 is suppressed (stopped). This is a case where the frame F1 from the terminal 4 has a large capacity and exceeds the storage capacity of the wired reception temporary storage device of the slave 3, and the slave 3 has a sufficient storage capacity of the wired reception temporary storage device. In the case where the terminal 4 is provided, it is not necessary to stop the transmission of the frame F1 of the terminal 4 unless the storage capacity of the wired reception temporary storage device is exceeded.

In the optical wireless communication system, the communication between the master unit 1 and the slave unit 3 is realized by the above-mentioned basic procedure. However, as described above, in such an optical wireless communication system, the master unit 1 It is difficult to stably detect the optical line idle notification signal EP from. That is, as shown in FIG. 3, when the slave unit 3 requests the master unit 1 for transmission permission, it means that the optical line transmission request signal RQ does not reach within the transmission request waiting time [T-rx] of the master unit 1. However, there is a problem that a delay time occurs when the handset 3 carrier senses the optical line availability notification signal EP transmitted by the base unit 1.

Compared with the length [T-idle-tx] of the optical line idle notification signal EP actually transmitted from the base unit 1, the length [T-cs] of the carrier sense detected by the handset 3 is Indefinitely, it will take about [T-cs-dly] time, so
The time during which the slave unit 3 can make a transmission application to the master unit 1 (send the optical line transmission request signal RQ) is limited to [T-id-tx].

In this case, it is meaningless for the slave unit 3 to transmit the optical line transmission request signal RQ to the master unit 1 by monitoring the carrier sense length [T-cs] (that is, If the transmission request waiting time [T-rx] of the master unit 1 is not met), the transmission request is abandoned with respect to the detection result (carrier sense signal) of the optical line idle notification signal EP, and the light of other slave units 3 is transmitted. Avoid inadvertent collision with the line transmission request signal RQ.

Hereinafter, with reference to FIG. 3, an optical line idle notification signal EP (IDLE burst) transmitted by the base unit 1,
Optical line idle notification signal E that the handset 3 detects carrier sense
The temporal relationship with P will be described. FIG. 3 shows the timing when the master unit according to the present invention transmits the optical line availability notification signal EP,
7 is a timing chart showing an embodiment of a time relationship with a timing at which a slave unit detects an optical line idle notification signal EP by carrier sense.

In FIG. 3, the period of the optical line idle notification signal EP transmitted by the base unit 1 is [T-burst], the length of the optical line idle notification signal EP is [T-idle-tx], and the base unit is 1 [T-rx] is the transmission application waiting time for waiting for the optical line transmission application signal RQ from the handset 3, and the confirmation process of the signal received by the base unit 1 is performed, which is required for the processing such as the determination of the next light emission. Time is [T-pro
c], the length of the carrier sense when the handset 3 detects the optical line availability notification signal EP of the base unit 1 [T-cs], from the end of the transmission of the optical line availability notification signal EP in the base unit 1, the handset unit The delay time until the end of carrier sense in 3 is [T-cs-dl
y], the transmission request available time when the handset 3 can transmit the optical line transmission application signal RQ within the transmission application waiting time [T-rx] of the base unit 1 is indicated as [T-id-tx]. To do.

The time to be taken into consideration here is that the slave 3 is the master 1.
Optical transmission request signal R within the transmission request waiting time [T-rx]
It is the transmission request available time [T-id-tx] at which Q can be sent. This transmission request available time [T-id-tx] is [T-id-tx] = [T-rx]-[T-cs-dly], and the handset 3 has this transmission application available time [T-id-tx]. id-tx], and if the transmission request available time [T-id-tx]> 0 (in the section shown in (I) and (III) of FIG. 3), this optical line idle notification signal Send an application to the EP. On the other hand, when the transmission request available time [T-id-tx] ≦ 0 (in the section shown in (II) of FIG. 3), the slave unit 3 responds to this optical line availability notification signal EP by Try not to send the application.

Next, a specific configuration of the master unit 1 in the optical wireless communication system shown in FIG. 1 will be described. Figure 4
It is a block diagram showing an embodiment concerning a composition of an optical wireless communication device (master unit) of the present invention. The base unit 1 shown in FIG. 4 includes a wired line transmission means 5, a wired line output signal switching means 6, a wired line suppression pseudo signal generation means 7, an optical line frame reception means 8, an optical line frame detection means 9, and an optical line transmission application. Signal detecting means 10, optical line receiving means (light receiving part) 11, optical line availability notification signal generating means 12, control means 13, wire line receiving means 14, wire line frame detecting means 15, light line transmission timing delay means 16, optical Preamble generation means 1
7, an optical line output signal switching means 18, an optical line transmitting means (light emitting section) 19, and an optical line transmission permission signal generating means 37.

The control means 13 is a means for controlling the entire operation of the master unit 1 and controlling the communication with the trunk line 2 and the half-duplex optical communication with the slave unit 3. Further, the optical line receiving means 11 is means for receiving light from the outside in order to communicate with the slave unit 3 and converting an optical signal into an electrical digital signal. The optical signal received by the optical line receiving means 11 is supplied to the optical line frame receiving means 8, the optical line frame detecting means 9, and the optical line transmission request signal detecting means 10 as an electric digital signal.

The optical line frame receiving means 8 transmits a frame (signal supplied from the optical line receiving means 11) to the trunk line 2 until the transmission timing to the trunk line 2 based on the frame detection result of the optical line frame detecting means 9. ),
It is a means for outputting the secured frame to the wired line output signal switching means 6 at a predetermined transmission timing under the control of the control means 13.

The optical line frame detecting means 9 is a means for detecting a frame from the signal supplied from the optical line receiving means 11 and instructing the optical line frame receiving means 8 as a target received frame. Optical line transmission application signal detecting means 10
Detects the optical line transmission request signal RQ sent from any slave unit 3 from the signal supplied from the optical line receiving unit 11 and sends the detection result to the control unit 13. For example, which slave unit 3 is means for transmitting application information indicating ID information or the like indicating whether or not a transmission application has been made from 3 to the optical line transmission permission signal generating means 37.

The optical line transmission permission signal generation means 37 follows the instruction of the control means 13 and the optical line transmission request signal detection means 1
The optical line output permission signal AK to be transmitted to the slave unit 3 (slave unit 3 which has sent the optical line transmission request signal RQ) specified by the application information detected by 0, the optical line output signal switching means 18 It is a means to send to.

The wired line suppression pseudo signal generating means 7 generates a suppression pseudo signal when it is necessary to suppress the signal from the main line 2 (stop the frame from the main line 2) according to the instruction of the control means 13. , A means for sending the suppression pseudo signal to the wired line output signal switching means 6. The wired output signal switching means 6 receives the frame from the optical line frame receiving means 8 and the suppression pseudo-signal from the wired circuit suppression pseudo-signal generating means 7, and appropriately switches each signal according to the instruction of the control means 13 to wire the signal. It is a means for transmitting to the line transmitting means 5. The wired line transmission means 5 is means for transmitting the signal from the wired line output signal switching means 6 to the trunk line 2 as a trunk line output signal.

The wired line receiving means 14 is means for receiving a signal from the trunk line 2 and transmitting the received signal to the wired line frame detecting means 15 and the optical line transmission timing delay means 16. The wired line frame detection means 15 detects a frame from the signal supplied from the wired line reception means 14, sends the detection result to the control means 13, and detects the frame to the optical line transmission timing delay means 16. It is a means for transmitting the result.

The optical line transmission timing delay means 16 stores the frame detected from the signal supplied from the wired line receiving means 14 in a temporary storage device such as a FIFO based on the frame detection result of the wired line frame detecting means 15. It is a means for making a stand-by and sending the frame made to stand by to the optical line output signal switching means 18 according to the optical line transmission timing instructed by the control means 13.

The optical preamble generating means 17 transmits a synchronizing signal according to an instruction from the control means 13 before transmitting a frame to be optically transmitted to the handset 3 so that the handset 3 can be synchronized when receiving a frame. It is a means for generating a preamble signal (optical preamble: optical P) to be generated and sending it to the optical line output signal switching means 18. In accordance with an instruction from the control means 13, the optical line idle notification signal generating means 12 sends an optical line idle notification signal EP for notifying the slave unit 3 under the optical line that the optical line is available. Occurs,
It is means for sending to the optical line output signal switching means 18.

The optical line output signal switching means 18 follows the instruction from the control means 13 at any time, and the optical line transmission permission signal AK from the optical line transmission permission signal generating means 37 and the light from the optical line idle notification signal generating means 12 are outputted. The line idle notification signal EP, the optical preamble (optical P) from the optical preamble generation means 17, and the frame signal from the optical line transmission timing delay means 16 are switched, and the optical line transmission means 19 is switched.
It is a means to send to.

The optical line transmission means 19 is capable of controlling light emission and light emission stoppage by the control means 13, and outputs light to a wide range to the outside for communication with the handset 3. It is a means for converting an electrical digital signal appropriately switched and output by the line output signal switching means 18 into an optical signal and optically transmitting it.

Next, a specific configuration of the handset 3 in the optical wireless communication system shown in FIG. 1 will be described. Figure 5
It is a block diagram showing an embodiment concerning composition of an optical wireless communications device (slave unit) of the present invention. The cordless handset 3 shown in FIG. 5 includes an optical line transmitting means (light emitting section) 20 and an optical line output signal switching means 2
1, optical preamble generation means 22, optical line transmission application signal generation means 23, optical line transmission timing delay means 24, wired line frame detection means 25, wired line receiving means (terminal side receiving means) 26, control means (transmission application possible) Time determination means, transmission control means) 27, optical line reception means (light receiving section) 2
8, optical line frame detection means 29, optical line availability notification signal detection means 30, optical line transmission permission signal detection means 31, wire line transmission timing delay means 32, wire line suppression pseudo signal generation means 33, wire line output signal switching means 34, a wired line transmission means (terminal side transmission means) 35, a wired line no-signal time measuring means 36, and a carrier sense means 38.

The control means 27 is a means for controlling the overall operation of the handset 3 and controlling the communication with the terminal 4 and the half-duplex optical communication with the base unit 1. Further, the wired line receiving means 26 receives a signal from the wired line (terminal 4) and outputs the received signal to the optical line transmission timing delay means 2.
4, a means for transmitting to the wired line frame detection means 25 and a wired line no-signal time measuring means 36.

The wired line no-signal time measuring means 36 measures the time during which the signal from the wired line is in a non-signal state (when the reception of the signal from the terminal 4 by the wired line receiving means 26 is completed, the signal from the terminal 4 is received). Time when it does not come)
It is a means for sending the measurement result to the control means 27. The wired line frame detecting means 25 is a wired line receiving means 26.
Is a means for detecting a frame to be transmitted to the optical line from the signal received from the terminal 4, and transmitting the frame detection result to the control means 27 and the optical line transmission timing delay means 24.

The optical line transmission timing delay means 24 temporarily stores the frame detected from the signal received by the wired line receiving means 26 from the terminal 4 based on the frame detection result of the wired line frame detecting means 25, such as FIFO. It is a means for causing the device to stand by and sending the frame on standby to the optical line output signal switching means 21 in accordance with the optical line transmission timing instructed by the control means 27.

The optical line transmission request signal generating means 23, when a frame is transmitted from the terminal 4 according to the instruction of the control means 27 and the frame is transmitted to the base unit 1, the base unit 1 transmits to the optical line. An optical line transmission request signal RQ is generated when permission is required, and the optical line transmission request signal R is generated.
It is means for sending Q to the optical line output signal switching means 21.

The optical preamble generating means 22 transmits a synchronization signal before transmitting a frame to be optically transmitted to the master unit 1 so that the master unit 1 can synchronize with each other according to an instruction from the control unit 27. It is a means for generating a preamble signal (optical preamble: optical P) to be generated and sending it to the optical line output signal switching means 21.

The optical line output signal switching means 21 follows the instruction from the control means 27 at any time, so that the frame from the optical line transmission timing delay means 24, the optical line transmission application signal RQ from the optical line transmission application signal generating means 23, It is a means for switching each signal of the optical preamble (optical P) from the optical preamble generation means 22 and sending it to the optical line transmission means 20.

The optical line transmitting means 20 can control the light emission and the light emission stop by the control means 27, and in order to communicate with the handset 3, the light is transmitted to an external narrow range (directed to the base unit 1). Optical line output signal switching means 2 for outputting
1 is a means for converting an electric digital signal appropriately switched and output by 1 into an optical signal and transmitting the optical signal.

The optical line receiving means 28 is means for receiving light from the outside to communicate with the base unit 1 and converting an optical signal into an electrical digital signal. The optical signal received by the optical line receiving means 28 is converted into an electric digital signal by a carrier sensing means 38, an optical line idle notification signal detecting means 30, an optical line transmission permission signal detecting means 31, an optical line frame detecting means 29, and a wire. It is supplied to each of the line transmission timing delay means 32.

The carrier sensing means 38 detects the transmission carrier from the base unit 1 from the signal supplied from the optical line receiving means 28, and sends the detected transmission carrier to the optical line idle notification signal detecting means 30. Is. The optical line idle notification signal detecting means 30 is means for detecting and selecting the optical line idle notification signal EP from the transmission carrier detected by the carrier sensing means 38, and sending the detection result to the control means 27.

The optical line transmission permission signal detecting means 31 uses the signal supplied from the optical line receiving means 28 to allow the master unit 1 to permit the slave unit 3 to transmit a frame to the optical line. AK is detected, and the detection result is detected by the control means 2
It is a means for sending to 7. Optical line frame detection means 29
Detects the frame transmitted by the base unit 3 from the signal supplied from the optical line reception means 28, transmits the detection result to the control means 27, and detects the frame to the wired line transmission timing delay means 32. This is a means for transmitting a frame and a temporary standby (temporary storage) instruction for the frame.

The wired line transmission timing delay means 32 is
Based on the frame detection result of the optical line frame detecting means 29, the frame detected from the signal supplied from the optical line receiving means 28 is made to stand by in a temporary storage device such as FIFO, and is transmitted to the terminal 4 by the control means 27. It is a means for sending out the waiting frame to the wired line output signal switching means 34 according to the timing instruction.

The wired line suppression pseudo signal generation means 33 generates a suppression pseudo signal when it is necessary to suppress the signal transmitted from the terminal 4 connected by the wired line according to the instruction of the control means 27, It is a means for sending the suppression pseudo signal to the wired output signal switching means 34.

The wired line output signal switching means 34 receives the frame from the wired line transmission timing delay means 32 and the suppression pseudo signal from the wired line suppression pseudo signal generation means 33, and follows an appropriate instruction from the control means 27 at any time. It is a means for appropriately switching these frames and suppression pseudo-signals and sending them to the wired line transmission means 35. The wired line transmission means 35 is means for transmitting the signal from the wired line output signal switching means 34 to the wired line to which the terminal 4 is connected.

Next, with reference to FIGS. 6 to 9, in the optical wireless communication system having the master unit 1 shown in FIG. 4 and the slave unit 3 shown in FIG. 5 as constituent elements, the timing chart of FIG. A process for realizing the communication procedure will be described.

First, referring to FIG. 6, the process in the main unit 1 until the main unit 1 receives a frame transmitted via the trunk line 2 and transmits the frame to the subordinate unit 3 under its control (main First, the processing in the control means 13 of the parent device 1) will be described. FIG. 6 is a flowchart showing the flow of processing in the master unit until the master unit receives the frame sent via the trunk line according to the present invention and transmits this frame to the slave unit under its control.

First, the control means 13 of the base unit 1 monitors whether or not the optical communication is performed with the handset unit 3 (whether or not the optical line is used), and the optical line is used. If not, in step S1, the transmission of the optical line idle notification signal EP is started toward the slave unit 3 under the control. Next, in step S2, it is monitored whether or not a frame (signal) from the trunk line 2 is sent, and if there is no frame sent from the trunk line 2, a state of waiting for a frame from the trunk line 2 is entered. On the other hand, when the frame is received from the trunk line 2, the process proceeds to the next step S3.

In step S3, the base unit 1 checks the state of the optical line and determines whether the optical line has a vacancy and the frame received from the trunk line 2 can be output to the optical line. If it is determined that the optical line is used for communication with the handset 3 and there is no vacancy in the optical line, the master unit 1 stops the frame transmission from the trunk line 2 in step S8. , The suppression pseudo signal is transmitted to the trunk line 2, and it is confirmed in step S9 that the frame transmission from the trunk line 2 is stopped. When it is confirmed that the frame transmission from the trunk line 2 is stopped, step S1
At 0, the suppression pseudo signal is stopped, and a standby state is entered until a frame is received from the trunk line 2 again in step S2.

On the other hand, if it is determined in step S3 that there is a vacant optical line, then in step S4 the frame from the trunk line 2 waits in a temporary storage device such as a FIFO until a predetermined optical line transmission timing (that is, , Frame transmission is delayed until the optical line transmission timing). Then, in step S5, the optical line idle notification signal EP transmitted to the handset 3 is stopped, and in step S6, the optical preamble (for synchronizing the handset 3 at the time of frame reception before the frame transmission is performed ( (Synchronization signal) is transmitted, and subsequently, in step S7, in step S7.
Frame that was temporarily kept waiting at 5 (delayed frame)
Is transmitted to the handset 3.

When the transmission of the frame is completed, it is newly monitored whether or not the optical communication with the handset 3 is performed, and when the optical line is not used, In step S45, the transmission of the optical line idle notification signal EP for notifying that the optical line is idle is started toward the slave unit 3 under the control, and waits again until a frame is received from the trunk line 2 in step S2. It becomes a state.

Next, referring to FIG. 7, the master unit 1 permits the optical transmission application received from the slave unit 3 under its control, receives the frame from the slave unit 3 which has permitted the optical transmission, and receives this frame. The processing in the master device 1 (mainly the processing in the control means 13 of the master device 1) up to transmission to the main line 2 will be described.
FIG. 7 shows a master unit in which the master unit according to the present invention permits an optical transmission application received from a slave unit under its control, receives a frame from the slave unit to which optical transmission is permitted, and transmits the frame to the trunk line. It is a flow chart which shows a flow of processing.

First, in step S11, the control means 13 of the master unit 1 requests the optical line transmission request signal RQ from the slave unit 3.
Is detected, and if the optical line transmission request signal RQ from the handset 3 is detected, the transmission of the optical line idle notification signal EP is stopped in step S12, and in step S13, For the optical line, the optical preamble that is the synchronization signal and the application information of the handset 3 in the optical line transmission request signal RQ received from the handset 3 (ID of the handset 3 etc.)
And the optical line transmission permission signal AK in which is embedded.

In step S13, the optical line transmission permission signal AK
When the frame is transmitted from the child device 3, the parent device 1 monitors whether or not a frame (signal) is transmitted from the child device 3 in step S14.
In step S15, this reception frame is transmitted to the trunk line 2 while adjusting the transmission timing to the trunk line 2.

On the other hand, when the frame is not transmitted from the slave unit 3, the frame waits for the frame from the slave unit 3 for a predetermined time, and in step S16, the waiting time in the frame wait state exceeds the predetermined time. Determine whether or not. Then, if the frame is not transmitted from the handset 3 within a predetermined time, it times out, and it is monitored in step S17 whether or not a frame (signal) is transmitted from the trunk line 2.

When the frame is not sent from the trunk line 2, in step S18, the transmission of the optical line idle notification signal EP is started again in order to open the optical line to the slave unit 3 under it, while the trunk line is sent. When the frame is sent from the No. 2, the optical preamble of the synchronization signal is added to the received frame and transmitted to the optical line in step S19. The process of transmitting the frame from the trunk line 2 in and after step S17 operates according to the process shown in the flowchart of FIG. 5 described above.

Next, referring to FIG. 8, the slave 3 receives the frame sent from the master 1 and transmits the frame to the terminal 4 connected by the wired line.
The process (mainly the process in the control means 27 of the child device 3) will be described. FIG. 8 is a flowchart showing a flow of processing in the slave unit according to the present invention, which receives a frame sent from the master unit and transmits the frame to the terminal connected to the wired line.

First, in step S20, the control means 27 of the handset unit 3 starts from the optical line (that is, from the base unit 1).
Whether or not a frame is sent is monitored, and when the frame is not sent from the base unit 1, a state of waiting for a frame from the base unit 1 is entered. On the other hand, when a frame is received from the master device 1, the frame from the master device 1 is FIFO-received in step S21 until a predetermined wired line transmission timing.
And so on (that is, the frame transmission is delayed until the wired line transmission timing).

Then, in step S22, it is confirmed whether or not the frame from the terminal 4 is sent to the wired line. When the frame from the terminal 4 is sent (exists) to the wired line, in step S25, in order to suppress (stop) the frame transmission from the terminal 4, the suppression pseudo signal is transmitted to the wired line (terminal). Send to 4). The suppression of frame transmission in step S25 is performed until the frame transmission from the terminal 4 is stopped. Then, the frame transmission from the terminal 4 is stopped,
If a vacancy occurs in the wired line, in step S23 transmission of the suppression pseudo signal is stopped, and in step S24, the frame (delayed frame) temporarily held in step S21 is transferred to the wired line (terminal 4). Send to.

Next, with reference to FIG. 9, the process in the handset 3 until the handset 3 transmits the frame sent from the terminal 4 to the base unit 1 through the optical line (mainly, the handset) Three
The processing in the control means 27) will be described. Figure 9
FIG. 4 is a flowchart showing the flow of processing in the slave unit according to the present invention until the slave unit transmits a frame sent from the terminal to the master unit through an optical line.

First, in step S26, the control means 27 of the child device 3 monitors whether or not a frame is sent from the terminal 4 (that is, from a wired line), and the frame is not sent from the terminal 4. In this case, the terminal 4 waits for a frame. On the other hand, when the frame is received from the terminal 4, the frame from the terminal 4 is subjected to FIF until the predetermined optical line transmission timing in step S27.
A temporary storage device such as O waits (that is, delays frame transmission until optical line transmission timing).

Then, in step S28, the master unit 1
The optical line idle notification signal EP from the master unit 1 is monitored, and if the optical line idle notification signal EP from the base unit 1 is detected, it is synchronized with the base unit 1 in step S29. An optical preamble as a signal and an optical line transmission request signal RQ requesting permission for transmission to the base unit 1 are transmitted.

In step S29, the optical line transmission request signal RQ
Of the optical line transmission permission signal AK transmitted from the master unit 1, the slave unit 3 monitors whether or not the optical line transmission permission signal AK indicating permission of transmission is transmitted from the master unit 1 in step S30. Is transmitted, step S31
In step S32, the optical preamble (synchronization signal) is transmitted, and subsequently, in step S32, the frame (delayed frame) temporarily held in step S27 is transmitted to master device 1.

Further, in step S33,
If a frame for transmission to the base unit 1 is sent (exists) from the terminal 4, in step S34, the frame from the terminal 4 is temporarily stored in a FIFO or the like until a predetermined optical line transmission timing. The device is made to wait (that is, frame transmission is delayed until the optical line transmission timing).

Then, in step S42, if it is within a predetermined time from the time when the transmission of the frame in step S32 ends (that is, if the interval with the previously transmitted frame is narrower than the predetermined interval), the optical Without checking whether or not there is a free line, the process returns to step S31, and the optical preamble and the frame are transmitted following the previous frame. If a predetermined time or more has elapsed from the time when the frame transmission in step S32 ends, the process returns to step S26 and it is confirmed whether or not there is a vacancy in the optical line.

Further, in step S28, it is monitored whether or not the optical line idle notification signal EP from the master unit 1 is detected, and in step S30, the optical line transmission permission signal indicating permission of transmission from the master unit 1 is detected. In monitoring whether or not AK is transmitted, in steps S35 and S36, it is determined whether or not the waiting time until the signal is received exceeds a predetermined time. Then, when the predetermined time elapses and the time-out occurs in step S35 or step S36, the process proceeds to step S37.

In step S37, the slave unit 3 transmits a suppression pseudo signal to the wired line (terminal 4) in order to suppress (stop) the frame transmission from the terminal 4. Then, in step S38, it can be confirmed that the frame transmission from the terminal 4 is stopped, and if the wired line becomes vacant, the transmission of the suppression pseudo signal is stopped in step S39, and the initial state of step S26 is restored again. Return.

[0080]

As described above, according to the present invention, in order to realize communication between a trunk network and terminals,
In the optical wireless communication device on the terminal side for performing half-duplex optical communication with the optical wireless communication device on the main line side connected to the main line network,
From the signal received from the optical wireless communication device on the trunk side, the carrier sense means detects an optical line vacancy notification signal EP indicating that there is a vacancy in the communication line, and the control means (transmission request available time judging means) From the transmission timing at which the optical wireless communication device on the side transmits the optical line idle notification signal EP, it is determined whether or not a predetermined time or more has elapsed, and if it is determined that the predetermined time or more has elapsed, the terminal outputs from the terminal. Since the transmission of the optical line transmission request signal RQ notifying that the frame No. is transmitted to the trunk side optical wireless communication means is not performed,
In a 1: N optical wireless communication system, it is possible to prevent collision of optical line transmission application signals between a plurality of optical wireless communication devices on the terminal side and realize efficient communication.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of an optical wireless communication system including an optical wireless communication device of the present invention.

2 is a timing chart showing an embodiment of basic communication timing between a master unit connected to a trunk line and a slave unit connected to a terminal in the optical wireless communication system shown in FIG. .

FIG. 3 is a timing at which a master unit according to the present invention transmits an optical line idle notification signal EP and a slave unit sends an optical line idle notification signal EP.
3 is a timing chart showing an embodiment of a temporal relationship with the timing of carrier sense detection of the carrier.

FIG. 4 is a block diagram showing an embodiment relating to a configuration of an optical wireless communication device (master device) of the present invention.

FIG. 5 is a block diagram showing an embodiment relating to a configuration of an optical wireless communication device (slave unit) of the present invention.

FIG. 6 is a flowchart showing an embodiment of a flow of processing in the master unit until the master unit receives a frame transmitted via the trunk line according to the present invention and transmits the frame to the slave unit under the master unit. is there.

FIG. 7 is a diagram showing a case in which the master unit according to the present invention permits the optical transmission application received from the slave unit under the master unit, receives a frame from the slave unit to which the optical transmission is permitted, and transmits the frame to the trunk line. It is a flow chart which shows an embodiment of a flow of processing.

FIG. 8 shows an embodiment of a flow of processing in the slave unit, which is performed when the slave unit according to the present invention receives a frame sent from the master unit and transmits the frame to the terminal connected to the wired line. It is a flowchart.

FIG. 9 is a flowchart showing the flow of processing in the slave unit according to the present invention until the slave unit transmits a frame sent from the terminal to the master unit via an optical line.

[Explanation of symbols]

1 Optical wireless communication device (master device) 2 Trunk line (network trunk line) 3, 3a, 3b, 3c Optical wireless communication device (slave device) 4, 4a, 4b, 4c Terminal 5, 35 Wired line transmission means 6, 34 Wired line Output signal switching means 7, 33 Wired line suppression pseudo signal generating means 8 Optical line frame receiving means 9, 29 Optical line frame detecting means 10 Optical line transmission request signal detecting means 11, 28 Optical line receiving means (light receiving part) 12 Optical line Free-space notification signal generating means 13 Control means 14 Wired line receiving means 15, 25 Wired line frame detecting means 16, 24 Optical line transmission timing delay means 17, 22 Optical preamble generating means 18, 21 Optical line output signal switching means 19, 20 Optical Line transmitting means (light emitting unit) 23 Optical line transmission application signal generating means 26 Wired line receiving means (terminal side receiving means) 27 Control means (transmission application) Available time determination means, transmission control means) 30 Optical line idle notification signal detection means 31 Optical line transmission permission signal detection means 32 Wired line transmission timing delay means 35 Wired line transmission means (terminal side transmission means) 36 Wired line no signal time measurement Means 37 Optical line transmission permission signal generating means 38 Carrier sense means

Claims (2)

[Claims] 1. In order to realize communication between a trunk network and a terminal, a trunk side optical wireless communication device connected to the trunk network and a terminal side optical wireless communication device connected to the terminal are provided. In the optical wireless communication system configured to perform half-duplex optical communication between the optical line communication devices on the main line side and the terminal side, the optical radio communication device on the terminal side, from the terminal to the main line network Terminal side receiving means for receiving a frame to be transmitted, optical line receiving means for receiving an optical signal from the trunk side optical wireless communication device, and the trunk side optical wireless communication device from the optical signal Carrier sense means for detecting an optical line idle notification signal indicating that there is an empty communication line between the device and its own device; and the optical wireless communication device on the trunk side sends the optical line idle notification signal. From the transmission timing, the transmission application available time determining means for determining whether a predetermined time or more has elapsed, and if the transmission application available time determination means determines that the predetermined time or more has elapsed, from the terminal And a transmission control means for controlling so as to prohibit the transmission of the optical line transmission application signal for applying to transmit the frame to the optical wireless communication means on the trunk side to the optical wireless communication means on the trunk side. An optical wireless communication device having. 2. When the transmission control unit controls the transmission of the frame, a suppression pseudo signal generation unit that generates a suppression pseudo signal including an instruction to stop the transmission of the frame from the terminal, and the terminal, The optical wireless communication device according to claim 1, further comprising: a terminal-side transmitting unit that transmits the suppression pseudo signal.