RU2589318C2 - Method of alternate one-way transmission of messages with disconnected information sources in common zonal communication network with exponential distribution of time slots - Google Patents

Abstract

FIELD: communication.

SUBSTANCE: invention relates to broadcasting systems for one-way transmission of data packets by several message sources in general zonal communication network, which is a multi-user channel. Method for alternate one-way transmission of messages by disconnected information sources in general zonal communication network, where conflict-free use of multi-user channel for transmitting messages by disconnected sources is ensured by detecting occupancy of network with other object - source of information on reception from said network of special marker called word for protocol exchange and predicting transmission of each message repetition based on used method for noiseless coding, determining time of occupancy of network and blocking its transmission of information at same time, installation of additional blocking transmission of information on time T1i depending on priority value pi assigned to each message source in said network.

EFFECT: technical result is non-conflict use of multi-user channel for one-way transmission of messages by different information sources.

1 cl, 1 dwg

Description

The invention relates to broadcast systems for one-way transmission of information packets by multiple message sources in a common area communication network, which is a shared channel.

In broadcast systems, a significant number of recipient objects receive messages, while the number of message source objects is limited and these objects are disconnected. In order to reduce the reception equipment from the recipient objects, it is advisable to use the channel of collective use for all disconnected objects-sources.

A prerequisite for using a shared channel is to ensure the sequential transmission of information from those source objects that currently have messages for transmission.

A known method of exchange with a temporary separation of the collective use channel ("Data transmission systems and computer networks" M., "Mir", 1974, p. 60). In the known method, the transmission of information in a shared channel from each message source is allowed in a strictly fixed time interval for it. The disadvantage of this method is the inefficient use of the bandwidth of the shared channel, since the duration of the time window for each message source does not depend on whether it has information for transmission, and if there is information on the transmission, it does not depend on the length of the transmitted message.

A known method of transmitting messages with random access of subscribers to the channel of collective use (Shcherbo V.K., Kirichev V.M., Samoilenko S.I. "Standards on local area networks", M., "Radio and communications", 1990, p. . 88). A known method of transmitting messages is that all message sources use a shared channel, on each message source that has data for transmission, monitor the state of this channel and, in the absence of transfers from other source objects, which is determined by the presence of a carrier frequency in the channel, transfer process. If, after the start of transmission, the message in the channel collides with the message transmitted by another source, then each of these source objects gives a random combination, recognized as false information, to the collective channel. Then the message source waits for a certain period of time, dynamically changed at random, before retrying the transmission. When a collision is detected again, the next attempt is made to transmit the message, while the waiting time is increased, but also remains a random value. In total, up to 16 such attempts are allowed, after which the shared access channel is rejected. The disadvantages of this method include the fact that:

- determination of channel occupancy by the presence of a carrier frequency can only be used for channels with high noise immunity;

- instead of allocating time windows for message sources, an algorithm is used to get out of a message collision situation, as a result of which there are cases leading to loss of information and delays in its transmission. The probability of these cases is the higher, the higher the intensity of message transmission in the channel of collective use;

- the use of the waiting time, the duration of which is determined randomly, in the algorithm for overcoming the collision situation, does not provide quick resolution of the conflict situation.

Closest to the proposed one is a method of packet exchange in a local network (Patent RU 2136113, 1999), which consists in the fact that the message source objects are synchronized (for example, from CEB), and the current time is divided into segments of equal duration Tc and assigned segments to message sources. At each message source object, the channel occupancy on “its” time segment is determined by analyzing the carrier during this interval and provided that no information transmission from other source objects is detected during the “own” TC interval, and if there is information to transmit it is transmitted in packets of the same length (Tn) in a synchronous manner so that the beginning of the packet coincides with the beginning of the next segment beyond “your own”, and the transmission of the packet completely ends within the allotted time interval, the value of which on is defined as T = TcN, where N - number of messages source objects in the network. The disadvantages of this method include the fact that:

- determination of channel occupancy by the presence of a carrier frequency can only be used for channels with high noise immunity;

- restriction on the length of the transmission packet (Tn = TcN);

- the need to synchronize the message source objects, which makes the implementation of the method dependent on the functioning of the external system (for example, on the SEB) and is difficult for disconnected objects.

The objective of the invention is the conflict-free use of a zonal network (shared channel) with low noise immunity for one-way transmission of messages by disconnected sources of information.

The problem is solved by the method of alternately unilateral transmission of messages by disconnected information sources in a common area communication network with an exponential distribution of time windows, in which the conflict-free use of the area network, which is a shared channel, for transmitting messages by disconnected sources is ensured by revealing the network is busy with another information source object by receiving from this network a marker called the word protocol of the exchange and preceding the transmission of each of repeat messages used method of error correcting coding, determine the time of the network of employment and blocking the transmission of their information at this time, as well as extra locks send your information to the time T1 _i, which depends on the assigned to each source message priority value of pi in the network, with the aim of determining the beginning of the closest i-th window, if this source has a message for transmission, or a reference interval T2 _i , also depending on the value of p _i , in order to determine the beginning of the next about the i-th transmission window, where i is the number of the information source in the given zone network, if this source does not have a message for transmission.

In order to achieve the goal of conflict-free information transfer in a zonal network, the information blocking procedure implements the transmission blocking procedure, which includes three complementary algorithms:

- identification of network occupancy by another source information object;

- determination of the network busy time and blocking the transfer of its information at this time;

- the countdown of the additional blocking of the transfer of its information, which depends on the priority of its source of information in this shared network with the goal of a conflict-free capture of the network by a higher priority source.

The method of transmitting data on one-way channels involves the use of error-correcting coding procedures that take into account the possibility of transmitting messages that have a variable length within specified limits.

The error-correcting coding method includes:

- splitting the message into linear blocks of constant length;

- noise-resistant coding of each linear block;

- repetition of the transmission of a sequence of linear blocks;

- precedence of each repetition of the sequence of linear blocks with a marker, called the word of the exchange protocol (STR), which is a constant-length code sequence that is protected from distortion in the communication channel by noise-resistant coding, which allows for the detection and correction of errors;

- STR contains information about the number of linear blocks (K _B ) in the transmitted message and the number of retries (K _P ) that remained until the end of the transmission session of this message.

Network occupancy is controlled by listening to its channels to receive information. The fact that a network is busy is recorded if a word of the exchange protocol (STR) is received from any channel of this network, preceding the transmission of each message retry using the data transmission method used.

The release of the network is fixed at the end of the transmission time of the message in all channels of this network.

The information transfer speed in the zone network (V), the length of the linear block (L _B) and the length of the STR (L _STR ) for the transmission method used are constant. Therefore, the value of the transmission time received from another source of information transmitting a message in a given network is calculated by the formula:

In the time interval from the moment of fixing the busy network to the moment of fixing its release, the transmission of messages to this network is blocked.

In order that after removing the transmission lock several sources of information working in a given network at the same time do not go into it, an additional transmission blocking is implemented in the time interval:

T1 _i = (2 ^Pi -1) t _f ,

where Ti is the time of additional blocking of the ith information source;

p _i is the priority of the i-th information source in the common area network;

t _f - time fixation of network occupancy.

The value of "p _i " is set by the directive introduced by the operating service, and should be different for each source of information on the network. The value of "p _i " is set within 0≤p _i ≤N-1, where "N" is the number of source objects connected to this zone network one-way messaging. For the highest priority source of information in this network, p0 = 0, therefore, for it T ₀ = 0.

The time of fixing the network occupancy includes the time of access of the transmitted information to the network, the time of bringing the STR and the time of analyzing the fact of network occupancy. A characteristic feature of the proposed method is that the value of time t _{f is} significantly less than the transmission time of the message,

The timing T1 _i provides for the i-th source of information the determination of the closest time i-th window of the start of transmission.

During the time T1 _{i, the} i-th information source controls by listening to the network channels for receiving information the presence of the fact that the network is busy as a more priority message source.

In the event that network busyness is detected by a higher priority message source, message transmission over the network is blocked until it is released.

If the network is not occupied by a more priority source of information and the ith information source has a message for transmission over the network, then it transmits this message and, at the end of the transmission, starts the countdown T1 _i again.

If the network is not occupied by a more priority source of information, but the i-th information source does not have a message for transmission, then it starts the countdown of determining the next i-th time window for starting transmission T2 _i :

T2 _i = 2 ^{Pi + 1} · t _f

If the i-th source has a message for transmission by the time T2i ends, then it transmits this message, after which it starts the time T1 _i .

If at the end of the countdown of time T2 _i the i-th source does not have a message for transmission, then it again starts the countdown of time T2 _i , etc.

The proposed method of alternating one-way messaging by disconnected information sources in a common zone communication network is based on the use of computer technology with software that implements the algorithm shown in FIG. one.

The proposed method of alternate one-way message transfer by disconnected information sources in a common area communication network using the above formulas for determining the variables T1 _i and T2 _i provides an exponential distribution of time windows for permitting the start of message transmission for different sources and can be used if there is an explicit priority distribution of objects sources on the network.

The transmission of messages by several information source objects using the proposed method is explained in the time diagram shown in the figure, showing the transmission of information by three sources.

As shown in FIG. In the 2nd example, the values T1 ₀ = 0, T2 ₀ = 2t _f , T1 ₁ = 1t _f , T2 ₁ = 4t _f T1 ₂ = 3t _f , T2 ₂ = 8t _f .

The moments of opening of the i-th time windows of permission to start the transmission of messages by the source with priority p _i in FIG. 2 are denoted by _i .

As shown in FIG. In an example of transmitting information, messages have different lengths.

The proposed method does not limit the duration of the transmitted messages, provided that they will consist of an integer number of linear blocks of constant length and the number of these linear blocks will be indicated in the STR in accordance with the noiseless coding method.

The proposed method of alternate one-way message transfer by disconnected information sources in a common area communication network provides an unambiguous distribution of the message transmission start windows between information sources. After organizational measures will one day ensure the seamless transmission of any one message from any source, then further the seamless transmission of messages in this network is ensured automatically.

Claims (1)

A method for alternately unilateral transmission of messages by disconnected information sources in a common area communication network with an exponential distribution of time windows, in which the conflict-free use of the area network, which is a shared channel, for transmitting messages by disconnected sources is ensured by detecting network occupancy by another source information object from this network marker, called the word protocol of the exchange and preceded the transmission of each repetition of the message using method of error-correcting coding, determining the network busy time and blocking the transmission of its information for this time, as well as setting an additional blocking transmission of its information for the time T1 _i , depending on the priority value p _i assigned to each message source in this network, in order to determine the beginning of the nearest i-th transmission window, if this source has a message for transmission, or the interval T2 _i , also depending on the value of p _i , in order to determine the beginning of the next i-th transmission window, where i is the number of the source of information in this zonal network, if this source does not have a message for transmission.

Images