RU2437146C1 - Device to eliminate access collisions - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: device comprises a unit with a retroreflector equipped with a light modulator, a photodetector, a beam divider and a control unit, switching modulator condition as the photodetector receives an optical signal interpreted as a logical unit from the other device, and an access unit comprising a transmitter of two types of optical signals, a logical zero and a unit, a receiver of optical zero signals and a comparator of intensities.

EFFECT: increased throughput capacity of communication facilities.

3 cl, 6 dwg

Description

The invention relates to the field of computer technology, in particular to devices for resolving access conflicts, and can be used to create multiprocessor and multi-machine computing systems to resolve conflicts that occur when multiple devices are accessed by one of the devices of the system.

The conflict is resolved by highlighting the only device with the highest or lowest priority that determines the access right.

Known devices that use various types of optical retroreflectors, the purpose of which is to return the incoming light beam to the light source. The device proposed in the application requires the use of a retroreflector working in conjunction with a light modulator. The most suitable for this device with a retroreflector, proposed in (US 6154299A, 11.28.2000). Figure 1 illustrates it. The corner reflector (retroreflector) 1 is shown here. 1. It can be a mirror retroreflector or a triple prism. In front of the retroreflector, a modulator 2 made using multiple quantum wells (MQW) is located, the signal generator 3 changes the light transmission level of the modulator 2. Figure 1 shows two faces of the retroreflector, which are visible in section in the plane of the drawing. In three dimensions, the retroreflector is a pyramid with three faces reflecting light. In the patent, the modulator can be located in front of the entire retroreflector or in front of its individual face.

The data receiver sends an unmodulated light beam to the retroreflector and receives a returned beam modulated by a modulator controlled by signal generator 3, which receives signals from an external data source via line 4.

In addition, as shown in figure 2, the modulator 6 can be located in front of an additional mirror 7 mounted in front of the retroreflector 5.

Along with the corner retroreflector, it is proposed to use a cat eye reflector (CER). In it, the rays pass through the lens, gather in its focal plane, are reflected from the mirror located in this plane, and, passing through the modulator, return to the light source.

In this application, in comparison with the well-known patent, a more complex function is required - the device must receive optical signals simultaneously arriving at the retroreflector from a group of sources, and, given their value, modulate the signals returned to the sources in a special way described below. In the cited patent, the device does not receive optical signals from external sources, but only modulates the reflected signals with its data.

A known access device with decentralized priority control corresponding to the objectives of the application is given in the copyright certificate (SU 291199, 03.16.1971) and taken as a prototype. The purpose of the device is to eliminate the conflict that arises when many devices try to simultaneously access the common channel that combines the source and receiver of information. Access to the channel is granted to the device based on its priority code. An access device instance is located in each of a group of digital devices having different priority codes. Each instance of the access device monitors the state of the communication channel to which only one of the digital devices with the largest (or smallest) priority code value needs to be granted access. When the access device detects a pause in the transmission of signals in the channel (the point in time when it is possible to start transmitting the priority code to the channel), it bitwise transfers the priority code to the channel one by one, performing the following access control method. The device is not granted access rights to the channel if, during the transfer of any bit by the access device, the latter transmitted binary zero, and at least one of the other access devices transmitted binary units. This method provides the allocation of the highest priority. When replacing "units" with "zero" in the specified method, the lowest priority is allocated. The access device can transmit electrical and optical signals. When using the optical signals that are used in this application, the signal transmitted by any of the access devices must be received by all other devices. This is a disadvantage of the access device, as it requires high transmit power.

The second disadvantage of the access device is that the channel is a resource common to all devices and, although it is necessary to resolve the conflict when establishing communication with a specific device, access to the channel prevents the operation of devices that do not access the specified device.

The invention is based on two devices - a device with an optical retroreflector and an access device with decentralized priority control, the combination of properties of these devices and allows to achieve a positive technical result of the invention.

The objective of the invention is to create a device for resolving access conflicts, which, in the presence of conflicts arising from the simultaneous access of several devices to one of the devices, eliminates the conflict: allocates the device with the highest or lowest priority without using a common channel that interferes with the operation of other devices, and uses signal source with low power optical signals.

The technical result of the invention is a significant reduction in the power of the optical signals sent by each device, since these signals are not scattered to be received by all devices, but are perceived by the retroreflector unit and the latter uses the received signal to modulate the signals sent by other devices. The common channel is also eliminated, which allows you to simultaneously eliminate several conflicts that occur when accessing various devices, thereby increasing the throughput of communication facilities.

The technical result is achieved by the fact that the device for resolving access conflicts contains a block with a retroreflector and an access block, while the first block is equipped with a light modulator, a photodetector, a beam splitter and a control unit that switches the state of the modulator when the photodetector receives an optical signal interpreted as a logical unit, and the second block contains a transmitter of two types of optical signals representing a logical zero and one, an optical signal receiver zero and an optical intensity comparator th signal zero transmitted and received by the access unit.

The photodetector is located behind the retroreflector.

A cat-eye retroreflector is used as a retroreflector.

The technical nature and principle of operation of the proposed device are illustrated by drawings.

Figure 1 shows a device with a retroreflector from (US 6154299A, 11.28.2000).

Figure 2 shows an additional mirror in a device with a retroreflector from (US 6154299A, 11.28.2000).

Figure 3 shows a block with a retroreflector and a control unit.

Figure 4 shows a block with a retroreflector and a beam splitter.

5 shows an access unit.

6 shows a combination of two access conflict resolution devices.

The proposed device for resolving access conflicts (hereinafter UKD) consists of a block with a retroreflector (passive block - PB) and an access block (active block - AB). UKD is capable of transmitting and receiving optical signals “1” and “0” having different wavelengths.

Block PB is shown in figure 3. In front of the light modulator 8 and retroreflector 9, a beam splitter (plane-parallel transparent plate, dichroic mirror) 10 is placed in the PB, which passes the signal to the retroreflector and partially reflects the signal to photodetector 11. The photodetector when receiving the optical signal “1” sends a signal along line 12 to the control unit 13. The node 13 is connected by a line 14 with a light modulator and with an external device using UKD. An external device on line 15 can control the modulator.

Figure 4 shows a second embodiment of the construction of the PB. In the PB unit, all the faces of the optical retroreflector 16 are partially transmissive to the optical signal arriving at them, for example, the faces are made of dichroic mirrors. The optical signals 18 passing through the retroreflector’s edges are received by the photodetector 18, which, when receiving the optical signal “1”, sends a signal to control unit 20 via line 19. Node 20 is connected by line 21 to the light modulator 17 located in front of the retroreflector and connected to an external device using this UKD.

A third option is possible for constructing a PB. It differs from the first option in that a cat-eye retroreflector is used as a retroreflector. The modulator may be located, as in options 1 or 2.

Further presentation is based on the first version of the PB.

The access unit - AB is shown in figure 5 and contains the following nodes: register 24, pause sensor 26, node 29 containing the optical signal transmitter 28, the optical signal receiver 32, comparator 31, the shift signal generator 33, the shift register 36.

The transmitter 28 is able to send two types of signals to the channel - "0" and "1", differing in wavelength. The receiver 32 is able to receive the signal "0" obtained by the remote retroreflector reflecting the signal "0" sent by the transmitter 28. The comparator 31 compares the signal levels "0" sent by the transmitter node 29 and received by its receiver.

The above blocks PB and AB in the UKD do not interact with each other and are located in relation to each other during the interaction of two mutually remote devices that eliminate the conflict, as shown in Fig.6.

If the first of these devices - the conflict resolution initiator interacts with the second device, when accessing which causes a conflict (the source of the conflict), then the CDS of these devices 40 should be located so that the optical signals sent by the transmitter 41 of the AB block of the first device 42 are received in the second device 43 to its retroreflector, and the signals returned by the retroreflector of the power unit of the second device to the battery unit of the first device to its receiver 44. Ensuring the required orientation time enii devices interacting in the composition is not a subject of the invention.

The proposed UKD operates as follows.

The beam splitter directs part of the optical signal received by it to the photodetector. The use of a dichroic mirror as a beam splitter makes it possible to increase the power of the optical signal “1” supplied to the photodetector. In the PB unit, the photodetector 11, upon receiving an optical signal “1”, produces an electrical signal. The signal from 11 arrives along line 12 to the control unit 13, which amplifies the signal and transmits via line 14 to the modulator 8, attenuating the light passing through it in both directions (incident and reflected). The signal from line 14 is also output to an external device. The external device can send signals to line 15 and further to the modulator. Thus, the block PB performs two functions. Firstly, any device that sends the optical signal “0” to the retroreflector 9 will receive it modulated (attenuated) if at least one optical signal “1” has arrived at the retroreflector. Secondly, by controlling the modulator, the external device can transmit its data to all devices sending the “0” signal to its retroreflector: if the “0” signal coming from outside is modulated, this means that this external device transmits “1”, otherwise they transmitted "0".

Block AB performs the following actions. An external device that needs access to another external device downloads its access code via bus 23 to node 24 of the AB block — the access code storage register, and through line 25 starts node 26 — the pause sensor. The pause sensor on line 27 sends a continuous signal to the optical signal transmitter 28 of node 29, which begins to continuously transmit the optical signal "0" in the direction of the unit of the device block with which you want to establish communication. At the same time, the node 26 begins to count a predetermined time interval - a pause. The node 26 receives signals from the comparator 31 of the node 29 via line 30, which provides a signal to line 30 if the comparator, comparing the signals of the transmitter 28 and receiver 32, determines the received optical signal "0" as modulated. The signal on line 30 stops the current pause count at node 26 and starts a new count. The signal from line 30 also enters the shift signal generator 33 and stops its operation if the node 33 previously worked.

The operation of node 26 can also be stopped by an external device by sending a stop signal to node 26 via line 34. In this case, the node 26 stops transmitting the optical signal "0" using the transmitter 28 of the node 29.

If the node 26 has completely counted the interval of a pause, then it returns to the initial state, stops sending the transmission signal “0”, sends a signal to the transmitter 28 via line 35, which starts the generator of shift signals 33, and copies the contents of register 24 to the shift register 36. Node 33 begins to send the shift signals to the shift register 36, which sends signals to the transmitter 28 along lines 27 and 37, initiating the operation of the transmitter. If the signal at the output 36 has a value of "1", then a signal is sent on line 37 and the transmitter transmits an optical signal "1". If the signal in 36 has a value of "0", then a signal is transmitted to the transmitter 28 via line 27 and the transmitter transmits an optical signal "0".

If the node 33 managed to transfer the entire contents of the shift register 36, then the node 33 sends a signal to the external device via line 38, allowing it to transmit data with optical signals, and using the lines 27 and 37, the external device starts transmitting its data.

To turn off the AB unit, the digital device sends off signals on line 34 to turn off node 26 and on line 39 to turn off node 33.

Thus, the AB unit will try to transfer the contents of register 33 until either the transfer is complete or the digital device turns off the AB unit.

The device described above is used as follows to resolve an access conflict.

To resolve the conflict, each digital device from the group of conflicting devices places its access code in register 2 of the AB block and starts the AB in operation.

If the digital device has the highest value of the access code, then with the help of the ACD it will completely transmit its access code and gain the right to exchange data with the device it needs.

At the same time, the conflict resolving device is able to receive data on line 22 of the power supply unit and transmit data by sending binary signals to the transmitter 28 of unit 29 of the power supply unit.

The actions of the conflict resolving group need to be synchronized. For this device, pending the opportunity to begin the process of resolving the conflict, transmit a continuous optical signal "0". The conflict resolution process begins if, within a single time interval for all devices, the signal received by the AB unit is not modulated, that is, the required device does not receive and does not transmit signals "1".

Claims (3)

1. Device for resolving access conflicts, characterized in that on each of the devices involved in the treatment of several devices to one of the devices, there is a block with a retro-reflector, equipped with a light modulator, a photodetector, a beam splitter and a control unit that switches the modulator state when receiving a photodetector from another an optical signal device, interpreted as a logical unit, and an access unit containing a transmitter of two types of optical signals representing a logical zero and one, an optical signal receiver zero and a comparator of the intensities of the optical signal zero, transmitted and received by the access unit. 2. The device according to claim 1, characterized in that the photodetector is located behind the retroreflector. 3. The device according to claim 1, characterized in that it uses a cat-eye retroreflector as a retroreflector.

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