RU2522851C2 - Method for dynamic reconfiguration of communication networks with multi-dimensional messaging routes - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: each communication node performs link quality control; link quality control results are transmitted to all communication nodes; link throughput is estimated depending on link quality; the throughput of one-dimensional messaging routes is determined depending on the throughput of links included in said one-dimensional route; a multi-dimensional messaging route is generated, wherein the one-dimensional route with the highest throughput is first included in the multi-dimensional route, then the one-dimensional route with the next, lower throughput until the throughput of the multi-dimensional route does not allow to transmit messages over a given time with the required probability of message delivery, and the message is then transmitted on the multi-dimensional route, wherein the communication nodes, based on the link quality control results, estimate the trend of change in link throughput, then estimate the trend of change in throughput of the one-dimensional route and then estimate the trend of change in throughput of the multi-dimensional route; if throughput of the multi-dimensional route falls below a maximum allowable value, the one-dimensional route is added to the multi-dimensional route, beginning with the remaining one-dimensional routes with the highest throughput until throughput of the multi-dimensional route reaches the required value based on the trend of change in throughput of the multi-dimensional route.

EFFECT: high communication network reliability.

6 cl

Description

The invention relates to the field of network information technology and can be used for dynamic reconfiguration of communication networks with multidimensional message transfer routes.

Complexes of communication equipment in many cases work as part of communication networks consisting of communication nodes and communication channels. Communication channels can be wired (cable and optical) or radio channels, for example, for mobile communication nodes. Communication channels are subject to the influence of many factors leading to a decrease in their quality, and in some cases to their failure and loss of communication. This reduces the reliability and survivability of communication networks, worsens their probability-time indicators. One of the main ways to improve the reliability and survivability of communication networks is to use dynamic reconfiguration of networks. Improving the reliability and survivability of communication networks allows you to build efficient robust communication networks that are resistant to the effects of damaging factors. The solution of this problem has practical applications in creating technologies for the dynamic reconfiguration of communication networks of mobile transport services in the area of deployment during the degradation of its individual components.

The structural redundancy of communication networks is created due to the fact that most nodes of communication networks are accessible to other nodes, and ideally form a fully-connected communication network in which each communication node is connected to all other communication nodes. The impact of damaging factors incapacitates part of the nodes and communication channels and breaks the fully-connected network structure, leaving a certain number of working communication nodes and backup routes. Characteristic when exposed to damaging factors is the failure at the first instant of time of a significant portion of the network structure, and then the gradual restoration of that part of it, which was located at a sufficiently large distance from the place of impact of the damaging factors. Communication channels can restore operational state over time. Radio channels are restored, and at the same time, the radio channels of the DKMV range are restored most quickly, which is explained by the physics of the ionospheric propagation of radio waves. Conducted channels with mechanical damage do not recover over time. In such a situation, the use of the method of dynamic reconfiguration of communication networks can ensure their reliability and survivability.

During dynamic reconfiguration of communication networks, the total network exchange traffic may remain unchanged, and the reduction of network exchange traffic in the channels of low-quality communication networks is carried out by increasing the traffic in other channels of higher-quality communication networks. This method allows more economical use of telecommunication resources of communication networks, does not change the structure of data transmitted in communication networks, is implemented at the level of routing and switching devices for message packets, and is the easiest to ensure the given reliability and survivability of communication networks.

We will call a one-dimensional transmission route a set of series-connected communication channels in a point-to-point connection between a communication node that is a message source and a communication node - a receiver of messages. A plurality of parallel connected independent one-dimensional transmission routes through which packets constituting the message are transmitted is called a multi-dimensional message transmission route. Depending on the quality of the one-dimensional transmission route, the information load of the one-dimensional transmission route is selected. The quality of the one-dimensional transmission route is determined by the quality of the communication channels included in the one-dimensional transmission route. In the event of a deterioration in the quality of the one-dimensional transmission route, the number of message packets sent by the routing device along the one-dimensional transmission route decreases to a value that provides a predetermined probability of message delivery. As the quality of the one-dimensional transmission route improves, the loading of the one-dimensional transmission route can be increased. The proposed method redistributes the information load between one-dimensional transmission routes of message packets depending on their quality, ensures the transmission of messages in a multi-dimensional transmission route when one-dimensional routes fail, and thereby increases the reliability and survivability of communication networks.

A known method for the dynamic reconfiguration of a communication network with multidimensional routes, in accordance with which in each of the communication nodes control the quality of the communication network channels and the magnitude of their network traffic. When the quality of the channels is below the permissible value or if the network traffic is above the maximum permissible value, the routing tables of the communication nodes are corrected, and message packets that must be transmitted along the one-dimensional transmission routes, which include these poor-quality channels, are sent by the communication nodes for transmission over other one-dimensional transmission routes according to routing tables of communication nodes. When improving the quality of communication channels or reducing their network traffic, the routing tables of the communication nodes are corrected, and message packets transmitted along other one-dimensional transmission routes are sent by the communication nodes for transmission along the restored one-dimensional transmission routes according to the routing tables of the communication nodes (Shuttle C. Computer World Networks: Translated from English by K .: BHV, 1996.288 s.).

The disadvantage of this method is the lack of reliability and survivability of the communication network, due to the fact that in the communication nodes when choosing a transmission route do not take into account the trend of changing the quality of the components of the communication channels.

There is also known a method for dynamically reconfiguring a communication network with multidimensional routes, according to which the quality of the communication channels included in the communication node is monitored in each of the communication nodes. The quality control results of communication channels are transmitted to all communication nodes of the communication network. If the quality of communication channels decreases below the maximum permissible value, one-dimensional transmission routes containing these low-quality communication channels are excluded from the routing tables of communication nodes, and message packets, which according to the routing tables of communication nodes should be transmitted along these one-dimensional transmission routes, are sent for transmission via other one-dimensional transmission routes according to the routing tables of the communication nodes. When restoring the quality of communication channels to the value necessary for transmitting message packets with a given probability, one-dimensional transmission routes containing these communication channels are restored in the routing tables of the communication nodes, and message packets transmitted earlier on other one-dimensional transmission routes are sent for transmission over the restored one-dimensional transmission routes, according to the routing tables of communication nodes (Mizin I.A., Urinson L.S., Khrameshin G.K. Messaging in networks with message switching. M., Radio and communications s, 1977. 328 pp.).

The disadvantage of this method also is to reduce the reliability and survivability of the communication network due to the fact that the quality of multidimensional message transmission routes is not taken into account, depending on the quality of the components of one-dimensional transmission routes.

Closest to the proposed method (prototype) is a method for dynamically reconfiguring a communication network with multidimensional routes, according to which the quality of the communication channels included in the communication node is monitored in each of the communication nodes. The quality control results of communication channels are transmitted to all communication nodes of the communication network. Depending on the quality of the communication channel, the throughput of the communication channel is estimated, then the throughput of one-dimensional routes is determined depending on the throughput of the communication channels included in this one-dimensional route. Next, a multidimensional message transmission route is formed along which the message is transmitted, first, in the multidimensional route, one-dimensional transmission routes with the highest throughput are included, then one-dimensional transmission routes with a lower, next largest transmission capacity, and so on, until the throughput a multidimensional transmission route does not provide a message at a predetermined time with the required probability of bringing the message, and then a message is transmitted along a multidimensional transmission route. (Kvashennikov VV, Shabanov AK. Adaptive routing method in a communication network with multidimensional message transfer routes. RF patent №2431945. Publ. 20.10.2011. Bull. No. 29).

The disadvantage of this method is to reduce the reliability and survivability of the communication network due to the fact that the trend of changes in the quality of communication channels constituting one-dimensional message transmission routes is not taken into account, and the formation of multidimensional message transmission routes does not take into account the loading of dedicated communication channels and public channels.

The purpose of the invention is to increase the reliability and survivability of the communication network due to the fact that when forming multidimensional message transmission routes, the trend of the quality of the communication channel channels is taken into account, as well as due to the fact that, first, less loaded and better and faster selected communication network channels, and only then use the communication channels of the public network.

To achieve the goal, a method for dynamically reconfiguring a communication network with multidimensional routes is proposed, according to which the quality of the communication channels included in the communication node is monitored in each of the communication nodes. The quality control results of communication channels are transmitted to all communication nodes of the communication network. Depending on the quality of the communication channel, the throughput of the communication channel is estimated, then the throughput of the one-dimensional message transmission routes is determined depending on the throughput of the communication channels included in this one-dimensional route. Next, a multidimensional message transmission route is formed along which messages are transmitted, first, in the multidimensional route, one-dimensional transmission routes with the highest throughput are included, and then one-dimensional transmission routes with a lower, next largest transmission capacity, and so on, until the throughput the ability of a multidimensional transmission route will not ensure the transmission of messages at a given time with the required probability of bringing the message, and then messages are transmitted along the multidimensional transmission route. What is new is that in communication nodes, which are message sources, according to the results of the quality control of the communication channel, the trend of changing the throughput of communication channels is also estimated, then the trend of changing the throughput of one-dimensional transmission routes is evaluated, and then the trend of changing the throughput of multidimensional transmission routes is evaluated. If the throughput of the multidimensional transmission route decreases below the maximum permissible value, one-dimensional transmission routes are added to the multidimensional route, starting from the remaining one-dimensional transmission routes with the highest throughput, and so on until the throughput of the multidimensional transmission route reaches the required value, taking into account the trend in the throughput multidimensional route capabilities. When forming one-dimensional transmission routes with equal throughput of communication channels, less loaded communication channels are selected first, and then more loaded communication channels. With unequal bandwidth, communication channels are first selected for which the throughput, taking into account their load, will be greater, then communication channels with a lower bandwidth are selected taking into account their load. At the same time, the quality of communication channels and their throughput is determined by the results of checks for the parity of the information part of the message, and when forming a one-dimensional route, first select higher-quality and less loaded dedicated communication channels, and then select public channels, while the initial formation of one-dimensional transmission routes for Bringing messages from the communication node, which is the source of the message, to the communication node, which is the recipient of the message, is performed according to the routing protocol ellma-on-Ford based communication network trial operation for a predetermined time.

The proposed method for dynamic reconfiguration of a communication network with multidimensional routes is implemented as follows.

In a communication network, communication nodes carry out continuous quality control of incoming communication channels. The quality control of the communication channel is performed according to the results of checks for the parity of the information part of the message.

Checks for the parity of the information part of the message are written as

$$r_i={\displaystyle \sum _{j\in J_i}{a}_j,i=\mathrm{one}...n-k}(\mathrm{one})$$

where r _i is the i-th parity check,

a _j - information symbols of the message,

J _i - the index set of information symbols of the message used in the i-th to a parity,

n is the block length of the message,

k is the informational length of the message.

If the parity checks of the information part of the message (1), calculated by the received information symbols, coincide with the parity checks received from the communication channel, then in this case the message is undistorted with a high probability. In a channel with independent errors, the probability of undistorted reception of a message containing n bits will be equal to

P _iè = (1-p) ⁿ ,

from here the average probability of error per bit or the error rate that determines the quality of the communication channel is written

$$p=\mathrm{one}-P_{i{}^{‵}e}^{\mathrm{one}/n}\text{,}\text{(2)}$$

that allows you to evaluate the quality of the communication channel according to the results of control checks for the parity of the information part of the message.

Then, in the communication nodes, depending on the quality of the communication channels, the throughput of the communication channel is evaluated depending on the signal-to-noise ratio, which corresponds to the quality of the communication channel. The average probability of error per bit depending on the signal-to-noise ratio for a channel with ABGS (additive white Gaussian noise) at OFM-2 (relative binary phase modulation) is written as

$$p=Q\left(\sqrt{2\cdot \frac{E_s}{N_0}}\right),(3)$$

- отношение сигнал-шум в дБ,Where $$\frac{E_s}{N_0}$$

- signal to noise ratio in dB,

- интеграл вероятности.but $$Q\left(x\right)=\frac{\mathrm{one}}{\sqrt{2\pi }}{\displaystyle \underset{x}{\overset{\infty }{\int }}{e}^{-\frac{t^2}{2}}dt}$$

is the probability integral.

Inversion of formula (3) allows us to determine the dependence of the signal-to-noise ratio on the average probability of error per bit in the communication channel. Unfortunately, it is not possible to obtain an explicit expression for the signal-to-noise ratio from formula (3). However, calculating the signal-to-noise ratio depending on the average probability of error per bit in the communication channel in a numerical form, for example, in the form of a table, is not difficult.

Now, according to the Shannon formula, you can get an estimate of the bandwidth of the communication channel depending on the signal-to-noise ratio. The channel capacity depends on the channel bandwidth F _n and the signal-to-noise ratio and is expressed as

$$C=F_{\ddot{l}}{\log }_2\left(\mathrm{one}+\frac{E_s}{N_0}\right).(\mathrm{four})$$

This value determines the maximum achievable message rate in the communication channel at which the probability of error in the message can be made arbitrarily small. The bandwidth of the communication channel allows you to select the transmission speed in the communication channel, which is usually always less than the bandwidth of the communication channel. The transmission speed determines the timeliness and likelihood of delivering messages. Thus, in the communication nodes of the communication network there will be information on the permissible transmission rates in the channels of the communication network. In the communication nodes of the communication network, a routing table of the communication node is compiled containing information about one-dimensional transmission routes to the remaining communication nodes of the communication network. The initial filling of the routing table can be performed, for example, according to the results of the pilot operation of the communication network in the period of time after putting it into operation or when changing the operating modes of the communication network, accompanied by a significant change in the state of the network. In other cases, additional iterative correction of routing tables is performed, which requires significantly less computation and transmission of a smaller amount of overhead information over communication channels. An overly frequent correction of routing tables of communication nodes can lead to erroneous route determination. On the other hand, too rare a change in the routing tables of the communication nodes will lead to the fact that the state of the communication network will not be quickly monitored and the probability-time characteristics of message delivery may decrease. The most appropriate correction of routing tables is carried out at time intervals, the duration of which is tied to the duration of the quasi-stationary states of communication channels, which is determined by the conditions of signal transmission and ripple load channels. If, after some time (usually 3-5 minutes), the probability-time characteristics of the communication channels deviate from the initial state by more than a threshold value, it is advisable to correct the routing tables of the communication nodes.

The Bellman-Ford routing protocol uses a heuristic dynamic programming algorithm, also known as a vector length algorithm. According to this algorithm, several of the most likely one-dimensional transmission routes are first selected. For each channel, the transmission rate in this communication channel is known, which determines the metric characterizing the quality of this communication channel. When forming one-dimensional transmission routes, the following randomly selected communication channels are added and the metrics of one-dimensional routes are calculated, continuing only the routes with the highest metric. It is important to keep track of ring routes and to exclude them from further consideration in time. If after a large number of tests the target communication node, which is the recipient of the message, is not reached, the number of initial most likely route options is increased and the procedure is repeated for them. As a result, we get some combination of the “fastest” routes, which we enter in the routing tables of communication centers. The routing table of the communication nodes stores information about one-dimensional transmission routes of message packets from this communication node, which is the source of messages, to the communication node, which is the recipient of messages. Moreover, the transmission rate of one-dimensional transmission routes is calculated for independent series-connected communication channels forming a one-dimensional transmission route in a point-to-point connection from the communication node that is the source to the communication node that is the recipient of messages. The total number of series-connected communication channels forming a one-dimensional transmission route is limited by the maximum allowable time for message delivery. The transmission rate of one-dimensional transmission routes is equal to the minimum transmission rate of the communication channels that are included in these routes. The routing table of the communication nodes for each one-dimensional transmission route contains the following fields:

1. address of the communication node-recipient of the message packet;

2. the number of transitions to the communication node-recipient of the message packet and the sequence of addresses of the intermediate communication nodes;

3. the metric of the one-dimensional transmission route, determined by the transmission rate of message packets along this route;

4. a timer for the release of the communication channel to the first communication node on the way to the communication node - the receiver of the packet.

In the communication node, the current state of the communication channel connected to the first communication node on the way to the target destination node of the packet is known: it is busy or free. Timer shows the time of release of the communication channel, if it is busy. One-dimensional transmission routes in the routing table of the communication node are ordered by the transmission speed, taking into account the busyness of transmission routes, that is, according to paragraphs 3 and 4 of the routing table of the communication node. The formula for the transmission rate of the communication channel, taking into account its employment, is written in the form

$${\nu }_{\mathrm{one}}=\frac{N}{T_t+T},(6)$$

where N is the length of the message packet,

T _t - timer time to release the communication channel,

T is the transmission time of the packet in the communication channel.

The transmission rate of a one-dimensional route is determined by the lowest transmission rate of the communication channel that is included in this one-dimensional route. One-dimensional transmission routes in the routing table are pre-ordered by quality. First, one-dimensional transmission routes with the highest transmission speed are selected according to formula (6) and free from message transmission, then the next one-dimensional transmission routes are selected with the highest transmission speed, free of message transmission, and they are terminated by one-dimensional transmission routes occupied by transmission of messages with the lowest transmission rate, the release of which according to the channel release timer occurs earlier than the allowable message transmission time.

Message transmission starts with breaking the message into message packets of a certain length. Then, according to the routing tables for each message packet, one-dimensional transmission routes are determined in the sequence of their location in the routing table of the communication node. Thereby, a multidimensional route for transmitting message packets is formed. The throughput of a multidimensional transmission route is calculated for independent parallel-connected one-dimensional transmission routes as the sum of the throughputs for the selected one-dimensional transmission routes, taking into account the trend in the throughput of communication channels.

In the communication nodes, which are the sources of messages, according to the results of the quality control of the communication channel, the trend of changing the throughput of communication channels is estimated. A short-term forecast of changes in the quality of communication channels allows more accurate selection of communication channels for message transmission.

The trend in the throughput of the i-th communication channel will be estimated by the formula

Tr _i = c ₁ -c ₀ ,

where c ₁ - the bandwidth of the communication channel at the current time,

c ₀ - bandwidth of the communication channel at the previous time, corresponding to the time of transmission of the message.

Then, the trend of changing the throughput of one-dimensional transmission routes is estimated as the maximum value by the absolute value of the negative trend for all channels included in this one-dimensional route

. $$T{r}_j=\underset{i}{\max }ads\left(T{r}_i\right),T{r}_i<0$$

.

Those communication channels are selected for which the trend in bandwidth changes is aimed at its decrease with time.

Next, the trend in the throughput of the multidimensional transmission route is estimated

. $$Tr={\displaystyle \sum _{j}T{r}_j}$$

.

At the same time, the trends in the throughput of all one-dimensional routes included in this multidimensional transmission route are summarized.

Taking into account the trend of changing the throughput of communication channels, the throughput of a multidimensional transmission route during a message can be reduced below the permissible value required to transmit a message at a given time. The short-term forecast of the throughput of the multidimensional transmission route, taking into account the trend in the throughput of the multidimensional transmission route, will be equal to

C ₁ = C ₀ + Tr.

If the throughput of the multidimensional transmission route decreases below the maximum allowable value taking into account the trend, one-dimensional transmission routes are added to the multidimensional route, starting from the remaining one-dimensional transmission routes with the highest throughput, and so on until the throughput of the multidimensional transmission route reaches a value required to send a message.

The packet transmission is accompanied by service information about the address of the packet receiving node, which allows each communication node of the one-dimensional transmission route, having received the message packet, to determine the further packet transmission route according to the routing table of the communication node. The number of one-dimensional transmission routes in a multidimensional transmission route depends on the length of the message, that is, the number of packets in the message. The formation of a multidimensional route is completed when all message packets are distributed between one-dimensional transmission routes. The last one-dimensional transmission routes used to form a multi-dimensional transmission route should have a throughput of at least a value that provides the required timeliness and probability of bringing message packets. Otherwise, the transmission of the entire message with the specified probability-time characteristics becomes impossible.

When forming one-dimensional transmission routes, the loading of communication channels should also be taken into account. With equal bandwidth of the communication channels, less loaded communication channels are first selected, and then more loaded communication channels. With unequal bandwidth, communication channels are first selected for which the throughput, taking into account their load, will be greater, then communication channels with a lower bandwidth are selected taking into account their load.

In the present invention, due to the formation of a multidimensional message transmission route based on one-dimensional packet transmission routes, the transmission quality and transmission capacity of which have the maximum value, the highest message transmission rate is ensured. In this case, dynamic reconfiguration of the communication network is performed. Communication channels of poor quality or with loss of communication are excluded from the messaging process, and unloaded communication channels of the best quality are selected. This allows you to timely send messages with a given probability and at a specified time to the recipient of the message. Moreover, preference is given to less busy and better dedicated communication channels, and then the public communication channels are selected. This increases the reliability and survivability of the network when exposed to damaging factors. The ordering of one-dimensional transmission routes in the routing table of a communication node by transmission bandwidth can significantly reduce the number of operations in the formation of multidimensional message transmission routes and reduce the complexity of the method.

The technical result achieved by the method of dynamic reconfiguration of the communication network with multidimensional routes is to increase the reliability and survivability of the communication network and reduce the complexity of the method.

Claims (6)

1. A method for dynamically reconfiguring a communication network with multidimensional routes, according to which the quality of the communication channels included in the communication node is monitored in each communication node, the results of the quality control of the communication channels are transmitted to all communication nodes of the communication network, depending on the quality of the communication channel, bandwidth of the communication channel, then determine the bandwidth of the one-dimensional communication routes depending on the bandwidth of the communication channels included in this one-dimensional route, then They form a multidimensional message transmission route along which messages are transmitted, first, in the multidimensional route, one-dimensional transmission routes with the highest throughput are included, then one-dimensional transmission routes with a lower, next largest transmission capacity, and so on, until the multidimensional transmission capacity the transmission route will not ensure the transmission of messages at a given time with the required probability of bringing the message, and then transmit messages along a multidimensional transmission route, distinguishing the fact that in the communication nodes, which are the message sources, according to the results of the quality control of the communication channel, the trend of changing the throughput of communication channels is also estimated, then the trend of changing the throughput of one-dimensional transmission routes is estimated, and then the trend of changing the throughput of multidimensional transmission routes is estimated, reducing the throughput of a multidimensional transmission route below the maximum permissible value, one-dimensional transmission routes are added to the multidimensional route, starting from the remaining one-dimensional transmission routes with the highest bandwidth, and so on, until the throughput of the multidimensional transmission route reaches the required value, taking into account the trend in the throughput of the multidimensional route, when forming one-dimensional transmission routes with an equal bandwidth of the communication channels, first select less loaded communication channels, and then more loaded communication channels, with unequal bandwidth, first select communication channels for which the starting capacity taking into account their load will be more, then communication channels with a lower bandwidth are selected taking into account their load. 2. The method according to claim 1, characterized in that the quality of the communication channels and their throughput is determined by the results of the checks for the parity of the information part of the message. 3. The method according to claim 1, characterized in that the transmission capacity of one-dimensional routes, taking into account the trend, is calculated for independent series-connected communication channels forming a one-dimensional route in a point-to-point connection from the communication node of the communication network that is the source to the node communication network, which is the recipient of the message, and the total number of series-connected communication channels is limited by the maximum allowable time for bringing the message. 4. The method according to claim 1, characterized in that the transmission capacity of the multidimensional route, taking into account the trend, is calculated for independent parallel connected one-dimensional message transmission routes, which are ordered in the routing table of the communication node of the communication network by the amount of bandwidth, starting from one-dimensional routes transmission of messages free of transmission with the highest bandwidth and ending with a one-dimensional transmission route occupied by the transmission of messages with the lowest bandwidth. 5. The method according to claim 1, characterized in that when forming a one-dimensional route, higher-quality and less loaded dedicated communication channels are first selected, and then public channels are selected. 6. The method according to claim 1, characterized in that the initial formation of one-dimensional transmission routes for bringing messages from the communication node that is the source of the message to the communication node that is the recipient of the message is performed according to the Bellma-on-Ford routing protocol taking into account trial operation communication network for a given time.