RU2611245C1 - Method and device for group deterministic conflict resolution with random switched device selection - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: every conflict message source sends a group of zeros and one single signal located in binary group, corresponding to the value of older source code priority rank in the struggle for resolution of the conflict to the receiver in the time scale. Number of bits in a group is equal to the maximum possible value of any position of priority code, each source randomly selects a sequence number of sending in a group in the scale, and ssending time respectively to the discovery of conflict is selected so that the group one by one in numerical order were received by a receiver. All sources obtain a sent sequence of groups from receiver, then the sources that matter most, with largest value of senior rank priority code, that perform similar actions with other ranks of priority code, remain at each group, and the only sources remaining in each group transmit messages without conflict.

EFFECT: opportunity to resolve access conflict in systems with large number of switched devices.

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Description

The invention relates to the field of computer technology and can be used to resolve conflicts of access to the receiver of messages from sources, each of which is connected to the receiver directly by a separate optical wireless communication channel using distributed switching tools located in each source.

Resolution of access conflicts is one of the central tasks of computer technology. Its solution is determined by the specific requirements of the system in which these conflicts arise. The decision depends on the number of objects that can potentially be sources of messages, as well as on the number of sources that simultaneously access the message receiver and create a conflict situation.

A known method of resolving conflicts of switched devices according to patent RU 2538314 C1 (prototype). The known method contains the following features similar to the method of the present patent.

(1) Sources and receivers exchange signals transmitted over wireless optical channels, individual for each source-receiver connection.

(2) Each message source knows the delivery time of its signal to the message receiver. This time can be measured in various ways, in particular during the initial placement of the system sources in space.

(3) At the same time, messages arriving at the receiver from several sources are sent by the sources so that the message bits of the same order of location arrive at the receiver simultaneously. This is achieved using the opportunity (2).

(4) The signals from (3) are combined by superimposing signals equally located in the message, and the message generated in this way is returned by the retroreflector to all sources of the initial messages. When combined, signal 1 cannot be distorted. The receiver has the ability to skip or not skip individual bits of the returned message to all sources (modulate message signals).

(5) Each source detects a conflict when it accesses the receiver.

(6) Sources can send signals to receivers using several signal frequencies. The receiver can modulate the signals of different frequencies returned to the sources independently of each other.

(7) The source must be able to send a signal either directly to the receiver or to an intermediary (relay), which is visible to the source and receiver. Further, these designs do not differ and the term “receiver” is used for them

(8) The source, having detected a conflict, sends the receiver a single signal so that the latter arrives at the receiver at a given point in time relative to the signals of other sources. This condition means that a timeline is being formed in which each source is allocated a corresponding scale category.

(9) The receiver returns to all sources its timeline. Each source determines the number of unit signals in the digits of the scale preceding the discharge of a given source. After that, the source that sent the signal indicated in (8) sends its message to the receiver with a delay sufficient for the receiver to receive messages from all sources that sent signals to the bits of the scale preceding the discharge of this source.

(10) Conflicts are resolved with a large number of them, up to the number of conflicts equal to the number of bits in the scale.

The prototype method has the following disadvantages. In the prototype, a source is allocated to each source in the scale. If the number of sources served by the switching system is so large that it is impossible or impractical to use scales with the required number of bits, then the method should form scales with fewer bits, taking into account the access rights of the sources to a particular receiver, and deliver them to the appropriate sources.

The second situation, in which it is impossible to allocate a discharge in the scale to each source, occurs if the sources have individual names (for example, device numbers assigned to each source by its manufacturer) and they are unknown to the system in advance.

Thus, there are areas of application in which the method of resolving a conflict of access to a receiver, used in the prototype, either significantly complicates and slows down the process of resolving a conflict, or is not feasible.

A device that implements the method according to patent RU 2538314 C1 (prototype) is known. The known device contains the following features similar to the device of the present patent. The device performs all the steps of the method described in this patent, with the exception of the formation and use of a timeline with a random number of bits. Moreover, in the prototype to perform all these actions, a specialized device is not created. All necessary actions are performed by the message source processor along with other actions for sending messages.

The disadvantages of the device:

- there is no way to resolve the conflict in systems with a large number of switched devices;

- low speed of conflict resolution due to the lack of a specialized conflict resolution device.

The objective of the present invention for the method is to eliminate these disadvantages of the prototype method, while ensuring the determinism of the conflict resolution method.

The present invention for the device is to eliminate these disadvantages of the prototype device.

The technical result for the method of conflict resolution is that it simplifies and accelerates conflict resolution due to the fact that the length of the timeline is not related to the number of sources and their names, and the latter use their priority codes randomly placed in the receiver scale, applying them to the struggle for the right to transmit messages in a conflict. Moreover, despite the randomness in the formation of the scales, the method guarantees a deterministic resolution of the conflict for any number of devices involved in the conflict.

The technical result for the method of conflict resolution is achieved by the fact that in it each conflicting message source sends to the receiver in the timeline a group of zero and one single signal located in the binary bit of the group corresponding to the value of the highest bit of the source priority code in the struggle for conflict resolution, while the number of binary bits in the group is equal to the maximum possible value of any bit of the priority code, each source randomly selects a group from the allowed number n, and the sending time relative to the moment of conflict detection is selected so that the groups one after another in the order of their numbering arrive at the receiver, and all sources receive from the receiver the sequence of signal groups transmitted to it, after which the sources with the highest senior value remain in each group priority code bit, then these sources send a scale to the receiver, moving the next priority code bit to the signal group, etc. until all bits of the priority code have been exhausted, and the only sources remaining in each group transmit messages without conflict.

The technical result for the conflict resolution device is that it eliminates the conflict in accordance with the proposed method, providing a quick response to the actions of the message sources involved in the conflict, both with a large number of message sources of the system, and with a large number of conflicting sources.

The technical result for the conflict resolution device is achieved by

that this device contains a buffer, a busy indicator of the message receiver, a conflict analyzer, a control unit, a random number sensor, while the buffer is connected to a message source, a busy indicator of a message receiver and a conflict analyzer are connected to a message source to receive receiver signals, the control unit is connected with a random number sensor to obtain a random number, connected to a source, buffer, indicator, analyzer to receive, respectively, a conflict resolution command, ala of a conflict, is connected to the source to be sent to the source of data on the status of action to resolve the conflict and the serial number of the source of the transfer of messages.

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

FIG. 1. The device scales and groups.

FIG. 2. Device for resolving access conflicts.

The device shown in the drawings should be considered as examples of the technical implementation of the device proposed in the patent.

A brief description of the proposed conflict resolution method. In the method, for a particular source, a group is randomly selected in the receiver timeline in which the source places a single signal. One and the same group can be selected at the same time by several sources. Sources that have chosen the same group are fighting among themselves for the right to transmit a message. Sources that won the struggle in all groups transmit their messages without conflict one after another without temporary gaps between them.

A brief description of the proposed conflict resolution device.

To perform the actions of the method for resolving a conflict, the device contains a buffer for storing control information received from the message source, a message receiver busy indicator, a random number sensor, a conflict analyzer, as well as a control unit that controls the listed devices and interacts with the message source to provide a conflict resolution.

A detailed description of the proposed method.

The source data for the method. As in the prototype, the above options 1-10 are considered implemented.

The source and receiver exchange optical signals wirelessly, as in the prototype. The signals have binary values 1 and 0, which can be represented for signal 1 by the presence of a signal, for signal 0 by the absence of a signal; binary values can also be represented by pairs of signals - 10 for value 1 and 01 for value 0; different frequencies for signals 1 and 0; different polarization of signals 1 and 0. As in the prototype, the retroreflector of the receiver, having received the signals from the channels, combines them and the received common signal simultaneously sends to all sources of the received signals.

All sources transmit messages of the same length, as is done in the prototype.

Sources and the receiver detect a conflict identical to the actions of the prototype.

In the method, the one shown in FIG. 1 scale, starting with the label of the scale F, after which there is a sequence of groups G ₁ , ..., G _n having the same number p of binary digits. The digit corresponding to the value of the p-ary digit of the priority code contained in the group is equal to one, the rest are zeros. In FIG. 1 group G ₁ contains a value equal to 3 (in Fig. The numbering of bits in the group from right to left, starting from label F).

For the transmission of messages regarding which it is not known whether they are in conflict, and for messages for which a conflict is detected, signals of different frequencies are used.

The source transmits the signals of the first type of messages to the receiver at a frequency f ₁ and receives the signals returned by the receiver at a frequency f ₂ . For the second type of messages, these signals correspond to f ₃ and f ₄ .

In order to check whether the receiver is busy receiving a message from another source or not, the source sends the receiver a continuous signal of frequency f ₂ (f ₄ ) and checks whether the receiver modulates or not. The source sends a message with signals f ₁ (f ₃ ), by which the receiver modulates the signals f ₂ (f ₄ ) returned to all switched devices, respectively.

The source counts the time interval * T _i = T _max -T _i , where T _i is the time interval required for the source signal to reach the receiver, T _max ≥T _i for all i. This ratio is justified in the prototype.

Based on these inputs, the sources resolve the conflict in the following manner.

The way to resolve the conflict.

Step 1. The source shown in FIG. 1 organization of the timeline. The source randomly selects a group from the allowed number n and places the senior bit of its priority code into it. As indicated above, the code of each bit of the priority code is represented by a single signal in the k-th binary bit of the group, if the bit value is k, and the remaining bits represented by zero signals. The priority codes of all sources are different. In particular, source codes can be priority codes.

The source performs all the above operations before sending a message to the receiver.

Step 2. Before sending a message to the receiver, the source sends the receiver a continuous signal f ₂ and begins to monitor this signal returned by the receiver.

If the source detects that the receiver is not modulating the signal f ₂ , then this means that the receiver does not receive a message from another source. In this case, the source transmits its message to the receiver with the signals f ₁ and, for conflict detection, monitors this message returned by the receiver with the signals f ₂ . If a conflict is detected, the source proceeds to step 3. Otherwise, it completes the message transfer without conflict.

Commentary on step 2. In step 2, if the source detects a conflict during the transmission of the message, it stops transmitting and proceeds to step 3. However, at a high transmission speed and a sufficiently large distance between the source and the receiver, the conflict can be detected after the transmission of the message is completed. In order to detect a conflict in this case, each message must be started with an individual message name. A message can be destroyed so much that the source cannot recognize its name. However, the source knows the time of the expected return of the message, and the inability to detect the message name at this time is a sign of conflict.

Step 3. The source proceeds to use the frequencies f ₃ and f ₄ , freeing the channel with frequencies f ₁ and f ₂ . Before sending a message to the receiver, the source sends the receiver a continuous signal f ₄ and begins to monitor this signal returned by the receiver.

The source expects that there is no modulation of its signal f _{4 by the} receiver for a time interval> 3T _max sufficient to complete the current resolution of the conflict. After this point, any source can send a message without violating this resolution.

The source transmits a message to the receiver with signals f ₃ and, for conflict detection, monitors this message returned by the receiver with signals f ₄ . If there is no conflict, the source ends the transmission of the message. Otherwise, he proceeds to step 4.

Comment on step 3. The choice of 3T _max should be explained. Consider conflict detection. If a conflict arose in the receiver, then after a time interval T _max , it will be known to the source farthest from the receiver. The source will begin the conflict resolution process (step 4) and the first signal of this process will reach the receiver after the interval T _max , after T _{max the} conflict resolution signals will reach the farthest source, and the pause will disappear. Further, in the process of resolving the conflict, there will be no prolonged absence of signals. Now consider the completion of the resolution of the conflict. In the worst case, the last one to transmit the message in the sequence of messages resolving the conflict is the most distant source, there will be a pause that any source will detect in no more than 2T _max .

Thus, a 3T _max pause is sufficient to detect a lack of conflict resolution.

Step. 4. The source sends the receiver the start mark of the scale F, the data prepared in step 1 for the scale, and receives the scale returned by the receiver. The moment of the beginning of the transmission of the scale, as in the prototype, is selected so that the signals from all sources at the input to the receiver form a single time scale in which any source signal occupies the same discharge that the source selected.

To start the transmission of the scale, the source with the number i, having detected a conflict, counts the time interval * T _i . To transmit to the discharge a group of signals selected by the source, which corresponds to the value of the priority code bit, the necessary time delay is added to * T _i .

After that, the source analyzes the group returned by the receiver in the following way. Let the leading position in the group occupied by a single signal be equal to k. All sources that have selected this group and have a high-order priority code value <k, stop participating in resolving the conflict and refuse to transmit their message. The remaining sources go to step 5.

Step 5. The source sends the receiver a scale, as in step 4, but puts the next digit of the priority code into the group. The winner performs similar actions with this rank, etc. until all bits of the priority code are exhausted, after which the only remaining source in the group - the winner goes to step 6.

At steps 4 or 5, each source, observing the struggle, determines which groups are fighting, ignoring the groups located further from the label F than the group of this source. If the priority code contains a single bit, then step 5 is absent.

Step 6. All sources that won in their groups transmit messages one after the other as a single message without pauses between messages, ignoring those groups that did not participate in the struggle to resolve the conflict.

After performing step 5, the current access conflict is resolved.

Modifications to the method of resolving an access conflict.

Option 1: simplify the implementation of the method. In the method, step 2 is excluded. After step 1, step 3 is performed, in the description of which the phrase “The source switches to using frequencies f ₃ and f ₄ is excluded, freeing the channel with frequencies f ₁ and f ₂ ”. As a result of the modification, the technical implementation of the method is simplified, but there is no way to quickly transmit a non-conflicting message.

Option 2: variable-length messaging. In step 2, a variable-length message is transmitted, limited only by the system-wide agreement.

In step 3, after the scale returns to the sources, instead of a sequence of messages, a sequence of short pointers is sent. The source puts the length of its message (the number of packets of a fixed length) in its corresponding pointer. After this sequence returns, the source sends its message using the time delay described above.

Option 3: control the wait by the source of the start of the message. To do this, bits are added to the priority code that take into account the waiting time for the transmission of the message and the urgency of the message, which allows you to control the order of message transmission.

Comments on how to resolve an access conflict.

1. A particular case of a p-ary group is a binary group consisting of one binary digit. Actions with this group do not differ from the above, but the conflict resolution time in systems with high-speed transmission of signals increases, since in many applications the main time is spent on delivering the source priority discharge code to the receiver and returning the code from the receiver. Denote the time for conflict resolution for binary groups by T ₁ , for p-ary groups by T ₂ , then T ₁ = log ₂ p [(kt + 2L / c) / (ktp + 2L / c)] T ₂ . Here k is the number of groups, t is the duration of the priority code signal, L is the distance between the source and receiver, and s is the signal transmission rate. This follows from the equalities T ₁ = (kt + 2L / c) log ₂ N; T ₂ = (ktp + 2L / c) log _p N. For example, at L = 10 m, t = 10 ^-11 sec, p = 32, k = 10 we get T ₁ = 4.79 T ₂ .

2. The method at each execution is guaranteed to reduce the number of conflicts both with a large number of switched devices and with a large number of sources involved in the conflict. After completing all the steps of the method, messages will be transmitted without conflict to one source from each digit of the scale containing units.

A detailed description of the proposed device conflict resolution access.

A diagram of the device and its connection with the source are shown in FIG. 2, on which:

1 - message source; 2 - control unit; 3 - buffer; 4 - indicator of the busyness of the message receiver; 5 - random number sensor; 6 - conflict analyzer.

The blocks are connected in the following way.

Source 1 has channel 7 for transmitting to block 3 a priority code for the number of groups in the scale, the number of bits in the group of the scale, and for transmitting a command to block 2; channel 8 for receiving signals from block 2; channel 9 for transmitting signals from the source photodetector to blocks 4 and 6. Control unit 2 has a priority code shift control channel 10 in block 3, channel 11 for receiving data from block 3, channel 12 for receiving signal transmission detection signal from block 4 to the message receiver, channel 13, block 5 is turned on, channel 14 receives a random number from block 5, channel 15 receives a signal from block 6 about the busyness of the message receiver.

Blocks interact as follows.

Source 1 is an arbitrary source with serial number i, which uses the proposed conflict resolution method in the patent. He performs the following actions.

Message source 1 loads into block 3 a priority code, the number of bits in the receiver scale group, and the number of groups in the scale (necessary when generating a random number). In particular, these parameters can be unchanged for the system and set in advance. The source also loads into block 2 the value * T _i - the delay in the beginning of transmission of the scale given in the method and instructs in block 2 to resolve the conflict. In response to a command from the source, block 2 begins to monitor the signal coming from block 4 and transmits a signal to the source if the receiver is busy. The appearance of this signal allows the source to refuse to transmit a message to the receiver or to wait for its release. If the receiver is free (or freed), then a signal about it received by the source from block 2 allows the source to transmit a message. In this case, the source sends the signals from the receiver to the block 6 and if the latter detects a conflict, the signal from block 6 goes to block 2 and the latter sends a signal to the source about this.

Having received a signal from block 6, block 2, through the time interval * T _i = T _max -T _i specified in the method, sends the start mark of the scale F to the receiver through the source transmitter. In advance, before receiving a signal from block 6, block 2 receives the highest value from block 3 the bit of the source priority code and the value of the group to which it should send the value of the highest bit. Block 2 sends a signal to the receiver through the source transmitter, corresponding to the value of the highest order of the priority code. The place of this signal in the group is defined in the description of the method. To do this, within the scale, block 2 selects a group whose sequence number in the scale is equal to the number received by block 2 from block 5. Within the group, block 2 sends a signal to the group bit, the sequence number of which in the group is equal to the value of the highest order of the priority code.

Having sent the receiver a high-order bit of the priority code, block 2 proceeds to analysis of the set of signals received from the receiver sent to the group by blocks 2 of other sources. For this, block 2 checks for the presence of signals in the bits of the group older than those used by this block 2. When they are detected, block 2 ceases to participate in the resolution of the conflict. Otherwise, a similar check is performed for the second and all subsequent bits of the priority code. The signals corresponding to the values of each digit are sent similarly to actions with the first digit of the priority code so that, like the first digit, they fall into the group selected by block 2 in the scale.

During the described actions of the device, block 2 determines in how many groups preceding the selected block 5, the fight was fought.

After successfully checking all the bits of the priority code, block 2 sends a signal to the source, notifying that the source has received the right to transmit the message, and the number of participating groups in the fight located closer to the label F than the group of this source. Having received this information, the source will send its message with a delay, which allowed sending messages to all sources that used the indicated scale groups.

It is assumed above that the unit 2 of the device is a regular programmable controller, whose speed is sufficient to perform the steps of the method of resolving the conflict. If higher performance is required, then in block 2 you will need to abandon the use of programmable tools, but such modifications do not affect the essence of the invention.

Claims (4)

1. A method of resolving an access conflict, characterized in that each conflicting message source sends to the receiver in the timeline a group of zero and one single signal located in the binary category of the group corresponding to the value of the highest order of the source priority code in the struggle for conflict resolution, while the number binary bits in the group is equal to the maximum possible value of any bit of the priority code, each source randomly selects a group from the allowed number n, and The name of the package with respect to the moment of conflict detection is selected so that the groups, one after the other, in the order of their numbering, arrive at the receiver, and all sources receive from the receiver a sequence of signal groups transmitted to it, after which each group contains the sources with the highest value of the highest order of the priority code, then these sources send a scale to the receiver, moving the next bit of the priority code to the signal group until all bits of the priority code are exhausted, and the only remaining bits in each group conflict-free sources transmit messages. 2. The method according to p. 1, characterized in that for exchanging messages of variable length after the scale returns to the sources, instead of a sequence of messages, a sequence of short pointers is sent, and the source enters the length of its message in the corresponding pointer (the number of packets of a fixed length), and after returning In this sequence, the source, using a time delay, sends its message. 3. The method according to p. 1, characterized in that to control the wait by the source of the beginning of the transmission of the message, bits are added to the priority code indicating the message transmission waiting time and the urgency of the message used with the remaining bits of the priority code. 4. An access conflict resolution device, characterized in that it contains a buffer, a busy indicator of the message receiver, a conflict analyzer, a control unit, a random number sensor, while the buffer is connected to the message source, the busy indicator of the message receiver and the conflict analyzer are connected to the source messages for receiving receiver signals, the control unit is connected to a random number sensor to receive a random number, connected to a source, buffer, indicator, analyzer for the floor eniya respectively command to resolve the conflict, the signal of a conflict, is connected to the source to be sent to the source of data on the status of action to resolve the conflict and the serial number of the source of the transfer of messages.

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