JPH0774759A - Radio transmitter and terminal equipment used therefor - Google Patents

Abstract

PURPOSE:To prevent collision of signals through the simultaneous transmission of signals from plural terminal equipment possible for radio channel communication with a communication controller. CONSTITUTION:A communication controller 8 is provided with a communication control function and a means 64 sending a signal discriminated from a data signal to be sent as a non-busy signal at the time of non communication intermittently at a predetermined interval, and each of terminal equipments 7a, 7b, 7c is provided with a means 22 discriminating the data signal to be sent from the non-busy signal and a transmission enable means 34 setting a transmission enabled state by receiving the non-busy signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a communication control device and a plurality of terminals that wirelessly send and receive signals to and from the communication control device.
The present invention relates to a wireless transmission device that constitutes a LAN (local area network).

[0002]

2. Description of the Related Art A plurality of terminals that wirelessly send and receive signals using light or other electromagnetic waves are provided for each of one or more communication control devices (also called concentrators) that constitute a wired LAN. There is a wireless transmission device. FIG. 9 schematically shows a conventional CSMA wireless LAN device. 1a
And 1b are terminal devices, 2 is a communication control device,
3a is a transmission signal of the terminal device 1a, 3b is a transmission signal of the terminal device 1b, 4a is a reception signal of the terminal device 1a, 4b is a reception signal of the terminal device 1b, 5 is a transceiver, and 6 is a wired LA.
It is an N cable (coaxial cable, optical fiber, etc.). Note that 32 indicates a transmission signal of the communication control device 2, and 42 indicates a reception signal. When the terminal device 1a is about to start transmission, it is determined whether the received signal 4a is present or absent.
And the transmission signal 3a is transmitted when it is determined that there is no.

[0003]

[Problems to be Solved by the Invention] For example, the terminal device 1b.
However, there exists a state in which communication with the communication control device 2 is possible, but communication with the terminal device 1a is impossible. In this case, the timing chart is shown in FIG.
From the time t _a to t _b , the transmission signal 3 from the communication control device 2
2 is transmitted, and this is the reception signal 4 of the two terminals 1a and 1b.
a, 4b, and then the terminal device 1a receives the time t
_{When the} signal 3a is transmitted to the communication control device 2 after _c ,
Since the terminal device 1b can not recognize the transmission signal 3a of the terminal device 1a, causing a collision would be the transmission signal 3b sends example, time t _d after, it may break the transmission signal 3a in the middle. Therefore, according to the present invention, when the communication control device receives a transmission signal from any of the terminals within its range or when it is connected to a LAN cable and receives a signal on the LAN cable, the communication control device communicates from any terminal. The purpose is to prevent signal collision by disabling transmission towards the control device.

[0004]

In order to achieve the above object, according to the present invention, a communication control device having a communication control function intermittently makes a signal distinguishable from an original communication signal a non-busy signal at predetermined intervals during non-communication. The terminal device is provided with a means for discriminating an original communication signal from a non-busy signal, and a transmission permission means for receiving a non-busy signal to enable transmission.

That is, in a wireless transmission device having at least one communication control device and a plurality of terminals capable of wirelessly communicating with each of the communication control devices, the communication control device is one of the terminals. From the non-reception recognition means for recognizing that there is no reception signal, and according to the output signal of the non-reception recognition means, it is possible to recognize the other signal transmitted from the communication control device only when there is no reception signal. And a means for intermittently generating a non-busy signal, each of the plurality of terminals, the non-busy signal detection means for detecting the non-busy signal, the non-busy signal according to the output signal of the non-busy signal detection means. A wireless transmission device, comprising: a transmission permission unit that enables transmission to be started after detection.

Further, according to the present invention, a LAN 1 is constructed.
In a wireless transmission device having more than one communication control device and a plurality of terminals capable of wirelessly communicating with each of the communication control devices, the communication control device has no transmission signal on a line forming the LAN, And when there is no transmission signal and the reception signal depending on the non-reception recognizing unit that recognizes that there is no reception signal from any of the plurality of terminals that can communicate, and the output signal of the non-reception recognizing unit. Only means for intermittently generating a signal identifiable from other signals transmitted from the communication control device as a non-busy signal,
Each of the plurality of terminals, non-busy signal detection means for detecting the non-busy signal, and a transmission permission means for enabling transmission to be started after detecting the non-busy signal according to the output signal of the non-busy signal detection means, A wireless transmission device having the above is provided.

Further, according to the present invention, in a terminal used for such a wireless transmission device, the transmission permission means sets a random value in response to the first non-busy signal, and the non-busy signal received intermittently. And a means for starting transmission before the next non-busy signal is received when the count value of the non-busy signal matches the random value or has a predetermined relationship.

[0008]

When the communication control device is in the receiving state, the non-busy signal is not generated, and the non-busy signal is generated only in the non-receiving state. Since each terminal can enter the transmission permission state upon detection of the non-busy signal, when the communication control device is in the reception state, the transmission permission is not given and thus the communication is not disturbed. Further, since each terminal independently sets a random value, it is possible to extremely reduce the possibility that each terminal simultaneously starts transmission after receiving the non-busy signal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a wireless transmission device of the present invention and a terminal used therefor will be described below with reference to the drawings. FIG. 2 is a block diagram schematically showing a part of a LAN including the wireless transmission device of the present invention. In FIG. 2, the transceiver 5 is a LAN
It is assumed that the LAN cable 6 is connected to a cable (coaxial cable, optical fiber, etc.), and that the LAN cable 6 is connected to other transceivers, terminals, etc. (not shown). A communication control device 8 is connected to the transceiver 5 and is capable of wirelessly communicating with a plurality of terminals 7a, 7b and the like using light or other electromagnetic waves. 7c is located far away,
When the medium is light, it is a terminal located outside the communicable zone of the communication control device 8 due to a position where the light beam does not reach. 9a, 9b, and 9c are the transmission signals from each terminal.
a, 10b, 10c show the received signals of each terminal,
Further, 98 is a transmission signal from the communication control device 8, and 108 is a reception signal of the communication control device 8.

The overall arrangement itself shown in FIG. 2 is the same as the conventional arrangement shown in FIG. 1 is a block diagram showing the configuration of a communication control device 8 in a first embodiment of a wireless transmission device of the present invention, and FIG. 3 is a block diagram showing the configuration of each of the terminals 7a, 7b, 7c. The terminal 7a will be described below. In the embodiment shown in FIG. 1 and FIG. 3, signals are exchanged between the communication control device 8 and the terminals 7a, 7b, 7c by a wireless transmission method using light such as near infrared light. In the communication control device 8 of FIG. 1, the light receiving unit 50 receives an optical signal from the light emitting unit 40 of the terminal 7a or the like of FIG. 3, and the optical signal sent from the light emitting unit 68 is received by the light receiving unit 20 of the terminal 7a or the like. .

First, the communication control device 8 will be described.
The output of the light receiving unit 50 is the carrier detector 52 and the signal processor 5.
4 inputs. The carrier detector 52 detects a carrier (referred to as a carrier a) of a received signal from any of the terminals 7a, 7b, 7c. Another carrier detector 58 connected to the output of the LAN interface (LAN I / F) 56 detects a carrier of a signal on the LAN cable 6 (referred to as carrier b). The signal processor 54 is a signal processor that performs necessary decoding, error check, synchronization correction, etc. in response to the received signal. The LAN I / F 56 is an interface for exchanging signals with the transceiver 5, and also has an L
It has a function of outputting to the signal processor 62 a transmission signal to the terminal 7a, 7b, 7c received from the AN cable 6 or the terminal 7a, 7b, 7c. LAN
The output of the I / F 56 is given to the signal processor 62 to perform necessary encoding, addition of error check bits, and the like.

Carrier detector 52 and carrier detector 58
Output signal, that is, detection of carrier a and carrier b
The signals indicating the detection of 1 are given to the controller 60, respectively.
The controller 60 can be composed of, for example, a CPU that operates according to the flow shown in FIG. That is, when this routine is started as shown in FIG. 5, step S0
At, the timer starts and measures the time. Next, in step S1, the presence or absence of the carrier a is determined, and the next step S
It is determined in step 2 whether or not carrier b exists, and when both carriers do not exist, the elapsed time of the timer is set to 1 in step S3.
A time wait is performed by determining whether or not the time is 6 BT (byte time) or more, and when 16 BT is reached, a predetermined non-busy signal is then generated in step S4. By repeating this operation, a non-busy signal is generated intermittently. Therefore, the controller 60 operates as a non-reception recognition means. This non-busy signal is a signal that can be distinguished from a data signal to be transmitted to the terminals 7a, 7b, 7c. Note that the data signal to be transmitted here means a data signal that includes the main information that is originally transmitted and received, and does not include a non-busy signal.

The communication control device 8 is the LAN cable 6
When there is no need to consider the signal on the LAN cable 6, such as when it is not connected to the LAN cable or when there is no signal sent from the LAN cable 6 even if it is connected, Only the absence of the carrier 9 need be detected. This variation will be described later as a second embodiment of the present invention.

As the non-busy signal, it is possible to use, for example, the shortest data of the data signal to be transmitted or a signal shorter than the packet length. In addition, each terminal 7a,
Although 7b and 7c have unique addresses, they may be non-busy signals including a predetermined address different from any of these addresses. Further, it may be a non-busy signal having a predetermined frequency different from the frequency of the data signal to be transmitted. That is, the intermittent signal generator 64 intermittently generates the non-busy signal according to the output signal of the controller 60. This intermittent non-busy signal has a pulse width of 4 BT in this embodiment, and the interval between consecutive pulses is 1 as can be seen from the waveform indicated by 98 in the time chart of FIG.
It is 6BT. It is also possible to monitor the time when there is no carrier and change the interval of the non-busy signal according to the length.

The intermittent non-busy signal generated by the intermittent signal generator 64 is added to the output signal of the signal processor 62 by the adder 66, and the sum signal thereof is given to the light emitting section 68 and sent out as an optical signal. To be done.

Next, the terminal 7a will be described with reference to FIG. The output signal of the light receiving unit 20 is given to the intermittent signal discriminator 22 and the delay unit 24. The intermittent signal discriminator 22 corresponds to the form of the non-busy signal transmitted from the communication control device 8. That is, the data length is discriminated from the data signal to be transmitted by the means for judging the data length, detecting the address, and having the means for distinguishing the frequency by the BPF or the like. Since this non-busy signal is not a part of the communication data but is added by the communication control device 8, it is gated and removed by the gate 26 according to the output signal (intermittent signal pulse) of the intermittent signal discriminator 22. To be done. Therefore, the signal excluding the non-busy signal in the output signal of the light receiving unit 20 is given to the interface (I / F) 30 via the signal processor 28 similar to the signal processor 54. The intermittent signal pulse is also given to the controller 34.

The I / F 30 is connected to a device such as a computer (not shown) having a transmission / reception function. I / F3
The output signal of 0 is a signal processor 36 similar to the signal processor 62.
And its output signal is applied to a transmission controller 38 having a memory or a buffer. READ indicating that there is a signal to be transmitted from each terminal from the I / F 30
The Y signal is provided to the controller 34. The controller 34 is, for example, a CPU that operates according to the flowchart shown in FIG.
It can be configured by.

Here, the flowchart of FIG. 6 will be described. First, in step S11, the output signal of the intermittent signal discriminator 22, that is, the presence or absence of an intermittent signal pulse is determined. When the non-busy signal is received, there is an intermittent signal pulse, and it is determined in the next step S12 whether or not the READY signal is present. If there is a READY signal, the next step S13
The count value X is reset to 0. Next step S
At 14, a random number n is generated. This random number n is for setting a random time by a random value as described later, and can be set by selecting an arbitrary one from a plurality of numerical values in the random number table, for example. . In this case, if there are 16 random numbers, two terminals 7
The probability that a and 7b generate the same random number is 1/256.

In step S15 following step S14, a timer is started to measure time. Next, in step S16, similarly to step S11, the presence / absence of the intermittent signal pulse is determined again, and if there is the intermittent signal pulse, the count value X is incremented by 1 in the next step S18. That is, steps S16 and S18 have a function as a counter, and the count value X increases each time an intermittent signal is received. The next step S19 is a step of detecting that the random number n and the count value match, and when n = X, a transmission start command is generated in the next step S20. This transmission start command is given to the transmission controller 38 and the transmission signal from the signal processor 36 is given to the light emitting unit 40 to start optical transmission. Therefore, the controller 34 operates as a transmission permission means.

When there is no intermittent signal in step S16, the process goes to step S17 to determine whether or not a predetermined time of about 1 minute has passed (timeout). This step S17 is to wait for the next non-busy signal, and to return to step S11 when the non-busy signal is not received for a long time due to communication failure or the like. In addition,
In the present embodiment, the transmission is started after the count value X matches the random number n, but the transmission may be started after the count value X matches any function of the random number n. Further, as the transmission permission means, the terminal further transmits a signal requesting a connection to the communication control device 8, and in response thereto, the communication control device 8 transmits a signal acknowledging the connection to the communication control device 8. You may make it confirm that 8 and the terminal were connected.

Next, the overall operation of the communication control device 8 and the terminals 7a and 7b will be described with reference to the time chart of FIG. The numbers 9a, 10a, etc. in the figure correspond to those in FIG. Now, all of the terminals 7a, 7b, 7c are requesting transmission within the period from time t ₂ to t ₄ , and each transmission READ
It is assumed that the Y signal is generated within that period. In this state, it is assumed that a non-busy signal is intermittently transmitted from the communication control device 8 (signal 98). This signal 98
Is received by the two terminals 7a and 7b in the zone (signals 10a and 10b), but is not received by the terminal 7c outside the zone (signal 10c).

Two terminals 7 that have received a non-busy signal
Each of a and 7b operates as described above according to FIG. At this time, it is assumed that the random number n is set to 3 in the terminal 7a and the random number n is set to 5 in the terminal 7b. At time t _{1 in} FIG. 4, intermittent generation of the non-busy signal starts, as can be seen from the waveform of the signal 98. Time t ₂
When the communication control device 8 receives the transmission signal on the LAN cable 6, the non-busy signal is stopped and the data is transmitted from the communication control device 8. When the data transmission ends at time t ₃ , the non-busy signal is generated again at time t ₄ . The terminals 7a and 7b generate a random number n for setting a random period by using the first non-busy signal as a trigger. If the random number n is set as described above for each terminal, the terminal 7a receives the third non-busy signal and then
Before receiving the next non-busy signal, a transmission start command is generated at t ₅ to start data transmission. In this embodiment, since the interval between non-busy signals is 16 BT, data transmission is started within 14 BT after the end of the set random number th non-busy signal.

When the transmission from the terminal 7a is started at time t ₅ , the communication controller 8 stops the generation of the non-busy signal, so that the terminal 7b is in a state where the transmission permission is not given and the transmission start is suspended. Becomes Note that the terminal 7c also determines the non-busy signal, but the communication control device 8
Since it cannot receive the signal from, it does not start the transmission. Therefore, while the terminal 7a is transmitting, no transmission is performed from the other terminals 7b and 7c, and a signal collision is avoided.

Next, a second embodiment of the wireless transmission device of the present invention will be described. The second embodiment differs from the first embodiment in the configuration of the communication control device. FIG. 7 is a block diagram showing the configuration of the communication control device 8'in the second embodiment. The difference from FIG. 1 is that there is no carrier detector for detecting the carrier b, and other configurations are the same as those in FIG. Is.

FIG. 8 shows the communication control device 8 in the second embodiment.
It is a flow chart which shows operation of controller 60 'in'. This flowchart differs from the flowchart of FIG. 5 only in that the step of detecting the carrier b (step S2 of FIG. 5) is not provided. That is, in the second embodiment, only the absence of the carrier a of the received signal from the terminal is detected and the intermittent signal is generated.

As described above, according to the present invention, the non-busy signal is not generated when the communication control device is in the receiving state, and the non-busy signal is generated only in the non-receiving state. In order to distinguish the non-busy signal from the signal for the original data communication, it should be shorter than the shortest data length of the data signal to be transmitted, include a predetermined address, or have a frequency different from that of the data signal. can do. Each terminal can enter the transmission enabled state only when it detects this non-busy signal. Also, in order to prevent multiple terminals from starting transmission at the same time, the time from the first reception of a non-busy signal to the start of transmission is set randomly, so duplicate transmission from multiple terminals Can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram of a communication control device in a first embodiment of a wireless transmission device of the present invention.

FIG. 2 is a block diagram schematically showing a part of a LAN including the wireless transmission device of the present invention.

FIG. 3 is a block diagram of a terminal in the first embodiment of the wireless transmission device of the present invention.

FIG. 4 is a timing chart explaining the operation of the first embodiment shown in FIGS. 1 to 3.

5 is a flowchart showing an operation of a controller in the communication control device shown in FIG.

6 is a flowchart showing an operation of a controller in the terminal shown in FIG.

FIG. 7 is a block diagram of a communication control device in a second embodiment of the wireless transmission device of the present invention.

8 is a flowchart showing an operation of a controller in the communication control device shown in FIG.

FIG. 9 is a block diagram schematically showing a part of a LAN including a conventional wireless transmission device.

FIG. 10 is a timing chart for explaining the operation of the device of FIG.

[Explanation of symbols]

1a, 1b, 7a, 7b, 7c Terminals 2, 8, 8'Communication control device 3a, 3b, 4a, 4b, 9a, 9b, 9c, 10a,
10b, 10c, 3242, 98, 108 Radio signal 5 Transceiver 6 LAN cable 20, 50 Light receiving part 22 Intermittent signal discriminator (non-busy signal detecting means) 24 Delay device 26 Gate 28, 36, 54, 62 Signal processor 30, 56 I / F (interface) 34 Controller (transmission permission means) 38 Transmission controller 40, 68 Light emitting part 52, 58 Carrier detector 60, 60 'Controller (non-reception recognition means) 64 Intermittent signal generator (non-busy signal Means for intermittently generating) 66 adder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motoyasu Nagashima 3-3-3 Toyosu, Koto-ku, Tokyo NTT Data Communications Corp. (72) Inventor Kazuki Yanaka, Toyosu, Koto-ku, Tokyo 3-3-3 Inside NTT DATA Communications Corporation (72) Inventor Koji Nishimura 3-3-3 Toyosu Koto-ku, Tokyo Inside NTT DATA Communications Corporation

Claims (4)

[Claims] 1. A wireless transmission device having at least one communication control device and a plurality of terminals capable of wirelessly communicating with each of the communication control devices, wherein the communication control device is provided from any one of the terminals. Also, non-reception recognizing means for recognizing that there is no received signal, and, according to the output signal of the non-reception recognizing means, can be recognized as another signal transmitted from the communication control device only when there is no received signal. A non-busy signal detecting means for intermittently generating a non-busy signal, each of the plurality of terminals detecting the non-busy signal, and detecting the non-busy signal according to an output signal of the non-busy signal detecting means. And a transmission permission unit that enables transmission to be started after the wireless transmission apparatus. 2. A wireless transmission device having one or more communication control devices constituting a LAN and a plurality of terminals capable of wirelessly communicating with each of the communication control devices, wherein the communication control device connects the LAN to each other. There is no transmission signal on the line that constitutes it, and non-reception recognizing means for recognizing that there is no reception signal from any of the plurality of terminals capable of communicating with the non-reception recognizing means; A means for intermittently generating a signal distinguishable from other signals transmitted from the communication control device as a non-busy signal only when there is no transmission signal or the reception signal, and each of the plurality of terminals has the non-busy signal. A non-busy signal detecting means for detecting a transmission permission, and a transmission permission for starting transmission after detecting the non-busy signal according to an output signal of the non-busy signal detecting means. Wireless transmission apparatus characterized by a means, a. 3. The intermittently generated non-busy signal is shorter than the shortest data length of a data signal to be transmitted, or includes a predetermined address other than the unique addresses of the plurality of terminals. The wireless transmission device according to claim 1 or 2, wherein the wireless transmission device has a predetermined frequency different from the frequency of the data signal to be transmitted. 4. The terminal used in the wireless transmission device according to claim 1, wherein the transmission permission means sets a random value in response to the first non-busy signal, and the intermittent reception is performed. And a means for starting transmission before receiving the next non-busy signal when the count value of the non-busy signal coincides with the random value or has a predetermined relationship. A terminal used for a wireless transmission device.