RU2477921C1 - Method for synchronising in multi-level communication network, communication network and network node - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: in synchronising method communication organisation is made in several hierarchically organised levels with synchronising the nodes of lower level to higher level; subordinate node can have nodes subordinate to it, for which it is superior: each communication centre has its assigned time interval for receiving and transmitting; the exchange between superior and subordinate nodes is made in repeatable frame, during which there performed is the exchange with all subordinate nodes: time intervals of transmitting and receiving are preliminary distributed in frames of each network level. Multi-level communication network has several hierarchically organised levels with synchronising the nodes of lower level to higher level; subordinate node has nodes subordinate to it, for which it is superior. Network node has physical interface device, medium access device, interface device that consists of n (n≥1) interfaces that are connected to n terminating devices correspondingly.

EFFECT: extension of functional capabilities due to increase of efficiency of frequency resource use at guaranteed band pass for each subscriber, increase of communication system failure tolerance, including deliberate ones.

17 cl, 7 dwg

Description

The invention relates to the field of communication and can find application in hierarchically organized radio communication systems with multiple channel access for a fixed number of subscribers with a guaranteed bandwidth for each subscriber.

Known multiple access with time division (TDMA) to the communication channel, described in detail in the literature, in particular in [1] p. 728, [2] p. 429-431.

Known multiple access with time division (TDMA) to the communication channel with a fixed distribution of channels, presented in detail in the literature, in particular in [3] p. 683-705.

A disadvantage of the known methods is the presence of only two levels of the hierarchy (one main, or base, station and its subordinate stations).

Methods of random access to the channel are described in detail in the literature, in particular in [1] p. 746-755.

The disadvantages of these methods are to reduce the bandwidth of the communication channel with a high intensity of information exchange and a large number of subscribers; the presence of only two levels of the hierarchy (one main, or base, station and its subordinate stations).

A known method of synchronizing connections when communicating in a mobile communication system [4], in accordance with which communication with mobile stations is carried out through system channels of multiple access with time division of channels. The mentioned channels include control channels and graph channels, the frequencies of the reverse and forward communication lines of which are divided into frames, some of which can be determined dynamically by determining the initial frame.

The disadvantages of this method are the need for a dedicated channel for control; the presence of only two levels of the hierarchy (one main, or base, station and its subordinate stations).

The known method, device and communication network [5], according to which the prevention of conflicts between transmissions on the upward and downward communication lines is achieved in a duplex communication system with time division of channels by identifying a time segment used in the first direction of communication, and execution based on it selecting for the second communication direction such a time segment that will not overlap with the time segment used in the first communication direction.

The disadvantages of this method are the lack of guaranteed bandwidth provided to each subscriber (a request for the allocation of additional intervals for exchange may be rejected); the impossibility of organizing a multi-level hierarchical communication system; the presence of only two levels of the hierarchy (one main, or base, station and its subordinate stations).

A known method of organizing a wireless network with the formation of a tree of connectivity for use in determining the connection route between wireless devices [6].

The disadvantage of this method is the lack of guaranteed bandwidth provided to each subscriber (the request for the allocation of additional intervals for exchange may be rejected).

Closest to the technical nature of the proposed is a method of controlling a communication connection in a duplex communication system with a temporary seal [7].

The prototype method is as follows. In time division duplex mode, for each communication connection between mobile transceivers and / or stationary transceivers, a pair of time slots including a forward link time interval and a reverse link time interval are selected so that the gap between the time interval of the forward link and the time interval of the reverse link, which are assigned to the same or different carrier frequencies, is equal to the fraction of the duration of the frame tneniya and has a constant or variable value.

The disadvantages of the prototype method are:

- the need for dynamic configuration and reconfiguration of the network;

- the presence of systemic interference (all stations simultaneously operate in the same band, which is the cause of mutual interference);

- lack of unambiguity in the hierarchical construction of the network - the subordination of stations depends on environmental conditions and can change during operation (a single-level network with a relay function).

The objective of the proposed method is to create a synchronization method for a communication network with several levels of the hierarchy with guaranteed bandwidth for each subscriber and the minimum requirements for hardware resources.

To solve the problem in a synchronization method in a multi-level communication network based on time compression between mobile and / or stationary transceiver devices, the carrier frequencies predefined for the communication system are distributed over a certain number of time intervals with a predetermined duration so that the system communication has the ability to work in duplex mode with a temporary seal, in time intervals and, accordingly, the frequency ranges of the system communication is possible simultaneous setting of the maximum predetermined amount of bilateral communication connection in the forward and backward directions between the users of mobile transceivers or fixed transceivers of a communication system according to the invention is carried out in connection organizing multiple hierarchically organized levels synchronization lower level nodes to a parent; the subordinate node is configured to have subordinate nodes for which it is a superior; each node is assigned a time interval for receiving and transmitting allocated to it; the exchange between superior and subordinate nodes is carried out in a repeating frame, during which an exchange is made with all subordinate nodes; transmission and reception time slots are pre-allocated in frames of each network layer; subordinate nodes of the first level that do not have their own subordinate nodes, as well as subordinate nodes of other levels that do not have their own subordinate nodes, are synchronized to a higher node by searching and receiving a sync code at one of the preset frequencies for an interval exceeding the frame duration of a higher node with a subsequent periodic frequency change in the absence of reception of a sync code; second-level subordinate nodes having their own subordinate nodes work with their subordinate nodes in a second-level frame of duration T2 different from the duration of a higher-level third level T3 frame, searching for a higher-level node's sync code at predetermined intervals with periodic changes in the sync-code search frequency at intervals, sufficient to detect the sync code, and with a change in the duration of the frame by T3 when detecting the sync code and synchronizing exchange cycles; subordinate nodes of the third level, having their own subordinate nodes, work with subordinate nodes, and the exchange intervals of this subordinate node and the parent node are distributed in such a way that for any mutual arrangement of the exchange cycles of the subordinate node, at least one sync code will be taken from the parent node for the duration of one exchange cycle, and after the synchronization code is detected, synchronization is carried out; a superior node of the fourth level, having its own subordinate nodes and not having superior nodes, works with all subordinate nodes in a predetermined exchange cycle.

The description of the proposed method is illustrated by the diagram of the hierarchical communication system shown in figure 1; examples of the structure of the time cycle (frame) of the exchange between communication stations (nodes) are shown in Fig.2.

Information is transmitted in batches. The information part of the package includes control headers (preamble) and user information. The preamble contains a well-known code with fairly high correlation properties. This code (sync code) is used throughout the network. It is possible to use several sync codes, both at one and at different levels. The information includes the identifier of the station (node) transmitting this packet. It is possible to use various sync codes to identify stations (nodes).

A central station (CA) is a station to which stations of a lower hierarchy level can be connected, and therefore synchronized. A subscriber station (AS) is a station that is connected to a higher station (CA) but does not have any lower stations connected to it. The CA, in turn, can be connected to a higher-level CA (subordinate CA). In this case, for a higher level, it acts as a speaker.

CAs and ASs have only one transceiver that cannot transmit and receive data at the same time.

For example, in FIG. 1, stations 4, 3.1, 3.m are CAs, and stations 1.1, 1.n, 2.n, 3.k are ACs.

Communication between the CA and the slave stations (AS and CA) is carried out in a periodically repeating time cycle - frame (Tk). During one frame, the CA exchanges data (transmission and reception) with all slave stations.

A CA frame consists of exchange intervals with all subordinate stations, and also includes exchange / synchronization intervals with a higher CA.

An AS frame consists of exchange / synchronization intervals with a superior CA and may include standby intervals (no exchange or synchronization).

The distribution of the time-frequency resource, in the case of work on the radio channel, is as follows.

Each CA is allocated a set of frequencies and the frame structure is determined, sufficient for organizing communication with subordinate speakers and synchronization with a higher CA. For a CA that does not have a superior CA, time slots for synchronization with a higher level are not allocated in the frame. When executing the synchronization algorithm with a higher CA defined for the AS or CA, work is carried out in the corresponding frame intervals at the frequencies of the higher CA.

A wired or fiber optic communication line can also act as a transmission medium. In this case, the role of the frequency separation of the network levels is played by various network segments, the connection to which is carried out alternately in accordance with the frame structure.

Figure 2 shows: Tk - frame duration; Tprd - CA transmission intervals; Tprm - intervals for receiving CA; Tps - intervals for searching and receiving sync code from a higher CA; Tprd cs - transmission intervals to a higher CA; Tprm cs - reception intervals from a higher CA.

The durations of these intervals can be chosen arbitrary and, in the General case, are not equal to each other.

The sync search interval is the interval during which the station searches for (receives) the sync code from the upstream DS in the communication channel. When receiving the sync code and, if necessary, the information part of the packet on the subordinate CA, a decision is made to synchronize its own exchange cycle with the higher-level exchange cycle (adjusting the exchange cycle of the subordinate CA to the exchange cycle of the higher CA in order to match the exchange intervals between them).

Synchronization with a superior CA on a subordinate CA can be performed:

- in the intervals specially allocated for this, both intended for exchange with a higher CA (before the detection of the sync code — shown in FIG. 2), and additionally allocated for the search for sync code;

- in free (not occupied for exchange with the AU and subordinate CA) intervals;

- in the Tprm intervals, if at the beginning of this slot no preamble was found from the corresponding AS or subordinate CA (the interval is not busy - the corresponding AC or subordinate CA is not active);

- in Tpr intervals, if it is known that the corresponding AS or subordinate CA is not active.

For the simultaneous operation of all levels of the communication system and the organization of interaction of all stations, it is necessary that the cycles of exchanges of higher and lower CAs be combined (synchronized). For this, the proposed hierarchical multi-level communication system uses a set of synchronization algorithms for the levels of the communication system described below.

Communication network synchronization algorithm for speakers

The AS receives the sync code at one of the assigned frequencies for a time interval exceeding the frame duration of the superior DS.

For the case of operation at a fixed frequency (FF), reception is carried out continuously, the time to wait for the reception of the sync code in the intervals for waiting for the sync code (the time required for synchronization) is determined using the relation

where T _Ki is the duration of the exchange cycle of the central nervous system of the i-th level, respectively;

К _{ФС АС} - coefficient taking into account the necessary excess latency, providing a predetermined level of probability of receiving the sync code for the mode of the ФЗ.

When working in a channel with pseudo-random tuning of the operating frequency (MHF), the clock is received at one of the frequencies of the MHF set. If during the interval T _{OJ OCH the} reception of the sync code did not occur, then the frequency is considered to be “affected by interference” and the receiver is tuned to the next frequency from the set of frequency hopping frequencies.

Thus, for the case of operation in the channel with frequency hopping, the sync-code waiting time (time required for synchronization) is determined using the relation

where N _f is the number of frequencies used in one code;

To _{frequency hopping AC} - coefficient taking into account the necessary excess latency, providing a given level of probability of reception of the sync code for frequency hopping.

Upon receiving the sync code, the AS synchronizes its frame to a higher-level CA and performs the work according to the assigned frame structure.

Fixed-frame CA network synchronization algorithm

The CA transmits and receives data from the AS and the subordinate CAs according to the assigned frame structure. The search for the sync code of the superior CA is carried out in the intervals free from the reception and transmission intervals - the sync code waiting intervals.

The sequence of reception and transmission intervals in the frames of the CA and the higher CA is assigned so that regardless of the relative position of the frames, at least one clock code (or, if necessary, the packet) transmitted by the higher CA will necessarily coincide with the waiting interval for receiving the sync code (located inside the interval sync code expectations) on the CA.

For the case of operation at a fixed frequency, the time to wait for the reception of the sync code in the intervals for waiting for the sync code is determined using the ratio:

where T _Ki is the duration of the exchange cycle of the central nervous system of the i-th level, respectively;

_{KF FC} - coefficient taking into account the necessary excess latency, providing a given level of probability of receiving sync code for the PS mode.

For the case of operation in the channel with frequency hopping, the synchronization time is determined using the relation:

where N _f is the number of frequencies used in one code;

K _{FCCH FC} - coefficient taking into account the necessary excess latency, providing a given level of probability of reception of the clock for the frequency hopping mode.

Upon receiving the sync code, the CA synchronizes its frame to the higher CA. Before synchronizing the frame, the CA, if necessary, informs the subordinate CAs and ACs about the upcoming frame shift.

Communication network synchronization algorithm for a CA with a variable-duration frame

The CA transmits and receives information with slave stations in cyclical frames.

For the CA, two predefined frame types are assigned - the main frame and the search frame. The duration of the main frame is equal to (or a multiple of) the frame of the superior CA. The duration of the search frame is selected in such a way that, for any mutual initial time position of the frame of the superior CA and the search frame of the CA, after a time interval no more than specified, at least one transmission interval of the higher CA will coincide with the search interval of the CA. We call this time interval the synchronization interval (Tsynhr). Exchange with subordinates of the CA and AS is carried out both in the main frame and in the search frame.

In the absence of synchronization with a superior CA, the CA exchanges with subordinate stations in the search frame. The CA searches for the sync code at one of the given frequencies for a time interval exceeding Tsynhr. The search for the sync code is carried out in the search intervals (Tps) of the frame.

When a sync code is detected (received) from a superior CA to a CA, synchronization with the frame of the higher CA is performed and switching to the main frame.

In the event of a loss of communication with a higher CA, the CA goes back to the search frame.

For the case of operation at a fixed frequency (FS), the time to wait for the reception of the sync code (time for synchronization) is determined using the relation

where T _SYNCHR - the duration of the time interval of the synchronization of the CA i-th level, respectively;

To _PSF - coefficient taking into account the necessary excess latency, providing a given level of probability of receiving sync code for the PSF mode.

For the case of operation in the channel with frequency hopping, the sync-code waiting time (time required for synchronization) is determined using the relation

where N _f is the number of frequencies used in one code;

To _{PC hopp} - coefficient taking into account the necessary excess latency, providing a given level of probability of receiving the sync code for the frequency hopping mode.

Thus, for a time not exceeding T _{OJ FCH PC} (T _{OZH PPRCH PC} ) from the moment of synchronization, the synchronization of the operation of the CA with a higher CA.

Additionally, the duration of the current cycle (frame type) can be transmitted in the service information. When receiving a sync packet with service data, the subordinate CAs and ACs can use this information to select the duration of the current working frame.

Communication network synchronization algorithm for a CA with slot permutation

The CA, exchanging information with its subordinates, the CA and AS in the assigned frame, permutes the intervals of transmission and reception of information in successive frames so that the TPS slots in each next frame change their position relative to the beginning of the frame. The permutation is carried out in such a way that for a finite number of exchange cycles N, at least one sync code of the superior DS coincides with the Tps interval (it is inside the Tps interval). After detecting the sync code, the exchange cycle is adjusted to the higher CA and the interval permutation is stopped.

When working in a system with frequency hopping, after a time interval T≥N Tk,

where Tk is the frame duration, the frequency of the search (reception) of the sync code is changed.

Initial network synchronization algorithm for the CA

The subordinate CA prior to the organization of the exchange (for example, after switching on) with the subordinate CAs and ACs searches for the sync code during the Tnach time period, after which, in the absence of receiving the synchronization code from the higher CA, it works in the specified frame. The duration of Tnach is determined to be sufficient for detecting the sync code from the superior CA, provided that it is active (sends the sync code to the subordinate CAs and ACs). When operating in the frequency hopping mode, the search is carried out sequentially at a finite number of frequencies less than or equal to N _f .

For the communication system shown in figure 1, the synchronization algorithms are distributed as follows:

- for all speakers of levels 1, 2, 3, the synchronization algorithm of the communication network for speakers is used;

- for a level 2 CA, an algorithm is used to synchronize the communication network with a frame of variable duration;

- for a level 3 CA, a fixed-frame synchronization network communication algorithm is used;

- for a level 4 CA, an algorithm is implemented in a predetermined frame structure without synchronization to higher levels. The technical result is as follows:

- providing a hierarchical multi-level (more than two levels) communication system with the possibility of individual levels and parts of the network working autonomously with integration into a common network when other hierarchical levels or parts of a communication system are activated (turned on, restored, etc.);

- improving the efficiency of using hardware resources, which reduces the complexity, dimensions, power consumption and cost of the system;

- increasing the efficiency of using the frequency resource with a guaranteed bandwidth for each subscriber (no special control channels are required);

- increasing the stability of the communication system to failures, including intentional.

Thus, in the proposed synchronization method, the duplex mode of operation is excluded, code division of channels is excluded, restrictions are removed from the method of distribution of temporary channels, including and a restriction on the relative position of the forward and reverse communication intervals, a preliminary distribution of channels among users has been introduced, several hierarchical levels of communication have been introduced with their mutual synchronization.

A known wireless network for connecting devices wirelessly [6], comprising a master device and slave devices and means for communicating with a master device via a virtual channel with frequency hopping, wherein the sequence of frequency hopping of the virtual channel is a function of the master device address.

The disadvantages of the known devices include:

- high probability of mutual interference with the simultaneous operation of multiple devices;

- An initial network organization cycle is required;

- the channel is not free from competition;

- Mandatory use of frequency hopping.

Known mobile communication system [4], which communicates with mobile stations via system channels of multiple access with time division of channels.

The disadvantages of this communication system include:

- the presence of only two levels of the hierarchy (one main, or base, station and its subordinate stations);

- the need for a dedicated control channel;

- the need for a constantly updated database of subscribers. A telecommunication network [5] is known, comprising a support node, a base station and a mobile station of a mobile communication network, means for detecting a first channel used in a first communication direction by identifying an identification code of a mobile station from a message received from a mobile station, means for selecting a second a channel whose time segment will not overlap the time segment of the first channel.

The disadvantages of this network include:

- the need for a dedicated control channel;

- the presence of only two levels of the hierarchy (one main, or base, station and its subordinate stations);

- The channel is not free from competition.

The closest in technical essence to the proposed one is a wireless network [8], adopted as a prototype.

Figure 3 shows a diagram of a wireless prototype network with many network nodes, where it is indicated:

1 - the main network node; 2, 3, 4 - secondary communication nodes of the remote class RDC (1); 5, 6, 7, 8 - secondary communication nodes of the remote class RDC (2); 9, 10, 11, 12 - secondary communication nodes of the remote class RDC (3); 24 - remote class RDC (0); 25 - remote class RDC (1); 26 - remote class RDC (2); 27 - distance class RDC (3).

A prototype wireless network contains many nodes 1-12 of the network. The nodes 1-12 of the network exchange relevant useful data, control data, and synchronization data via radio channels. The nodes 1-12 of the network are synchronized with the main clock pulses that are supplied by the node 1 of the network. This host is designated as the host 1 of the network.

The main network node 1 transmits the synchronization combination via a wireless medium, and this synchronization combination is sent by the secondary network nodes in different distance classes so that the secondary network node of a hierarchically lower remote class is indirectly synchronized by the clock pulses of the clock source of the main network node 1.

In the case of a moving secondary network node and / or main network node 1, the remote class of the secondary network node is subject to change.

The synchronization combinations of each distance class are different.

A hierarchical structure of network nodes with remote classes RDC (i) is formed in a wireless network. Only the main node 1 of the network belongs to the remote class RDC (O). All secondary network nodes that are synchronized directly by the main network node 1 belong to the remote class RDC (1). All secondary network nodes that are synchronized directly by one or more secondary network nodes of class RDC (1) belong to the remote class RDC (2). Members of the remote class RDC (i) are formed by all secondary network nodes that are synchronized by one or more secondary network nodes of the remote class RDC (i-1).

Secondary nodes 2, 3 and 4 of the network in the example wireless network implementation, as shown in FIG. 3, belong to the remote class RDC (1), because these secondary nodes 2, 3 and 4 of the network can receive radio signals evaluated as reliable from the main node 1 network. The outer limit of the remote class RDC (1) is shown by ellipse 25. Ellipse 24 shows the remote class RDC (O). Remote class RDC (2) contains secondary nodes 5-8 network. It is assumed that the secondary network node 5 is synchronized directly by the secondary network node 2, the secondary network nodes 6 and 7 are synchronized directly by the secondary network nodes 3 and 4, and the secondary network node 8 is synchronized directly by the secondary network node 4. The outer limit of the remote class RDC (2) is shown by ellipse 26. The remote class RDC (3) includes secondary nodes 9-12 of the network. It is assumed that the secondary network node 9 is synchronized directly by the secondary network nodes 7 and 8, the secondary network node 10 is synchronized directly by the secondary network node 5, the secondary network node 11 is synchronized directly by the secondary network node 6, and the secondary network node 12 is synchronized directly by the secondary nodes 6 and 7 network. Ellipse 27 shows the outer limit of the remote class RDC (3).

At least in the UDS level, the use of a frame-synchronized PC signal (recommended standard) for radio data transmission between the main and secondary nodes 1-12 of the network is also carried out. This frame contains several time slots for synchronization data, control data, and payload data. The frame duration hereinafter will be represented by the letter D.

Figure 4 shows the transmission scheme for synchronizing combinations betrayed by the radio device.

The main node 1 of the network first transmits its synchronization pattern P (0). The duration of the synchronization combination is Tr. This is followed by a waiting period Ta, which should be selected so that the radio devices 13 of all secondary nodes of the RDC (1) remote class network have enough time to switch from the reception mode to the transmission mode. All secondary network nodes of the remote class RDC (1) then transmit the synchronization pattern P (1) with a duration of Tr. Each secondary network node of a remote class RDC (2) receives a synchronizing combination P (1) from one or more secondary network nodes of a remote class RDC (1). After a subsequent waiting period of Ta duration, each secondary node of a network of a remote class RDC (2) thus has its own secondary clock pulses synchronized with secondary clock pulses of a remote class RDC (1). Since the secondary clock pulses of the remote class RDC (1) are synchronized with the main clock pulses of the remote class RDC (0), the secondary clock pulses of the remote class RDC (2) are thus indirectly synchronized with the main clock pulses of the remote class RDC (0). All secondary network nodes of the remote class RDC (2) then transmit their synchronizing combination P (2). These synchronization operations continue until the secondary clock pulses are indirectly synchronized with the main clock pulses for all secondary network nodes in the most remote remote class RDC (n).

A synchronization channel is used to transmit the synchronization pattern P (i).

The disadvantages of the prototype network are:

- lack of a fixed hierarchy between radio stations,

- the need for dynamic reconfiguration of the network in the process,

- inefficiency in the use of bandwidth due to the cost of periodic transmission of service information about the network configuration,

- the need for a separate synchronization channel,

- Work only in a wireless network.

The objective of the proposed communication network is to create a network with several levels of hierarchy with guaranteed bandwidth for each subscriber and minimum requirements for hardware resources.

To solve the problem in a multi-level communication network containing many nodes, moreover, the network node, which is designated as the main network node, is intended to transmit the synchronization combination to all other network nodes, designated as secondary network nodes, while the secondary network nodes are intended to transmit the synchronization combination , each secondary network node is designed to synchronize the received synchronization combination - sync code, according to the invention several hierarchically organized levels are introduced s synchronization child to the next higher level nodes; the subordinate node has subordinate nodes for which it is a parent; each node is assigned a time interval allocated to it / reception and transmission intervals; the exchange between higher and subordinate nodes is carried out in a repeating frame, during which an exchange is made with all subordinate nodes; transmission and reception time slots are pre-allocated in frames of each network layer; subordinate nodes of the first level that do not have their own subordinate nodes, as well as subordinate nodes of other levels that do not have their own subordinate nodes, synchronize to a higher node by searching and receiving a sync code at one of the predetermined frequencies for an interval exceeding the frame duration of a higher node with a subsequent periodic frequency change in the absence of reception of a sync code; subordinate nodes of the second - higher than the lower level, having their own subordinate nodes, work with their subordinate nodes in a second-level frame with a duration of T2 different from the duration of a higher-level frame of the third level T3, with a search for the sync code of the higher node in a predetermined interval / intervals with a periodic change in the frequency of the search for the sync code at intervals sufficient to detect the sync code, and with a change in the duration of the frame by T3 upon detection of the sync code and synchronization iklov exchange; subordinate nodes of the third level, having their own subordinate nodes, work with subordinate nodes, and the exchange intervals of this subordinate node and the parent node are distributed in such a way that for any mutual arrangement of the exchange cycles of the subordinate node, at least one sync code will be taken from the parent node for the duration of one exchange cycle, and after the synchronization code is detected, synchronization is carried out; a superior node of the fourth level, having its own subordinate nodes and not having superior nodes, works with all subordinate nodes in a predetermined exchange cycle.

An example of network organization is shown in Fig. 5, where stations (nodes) 1, 3.3, 2.3 are central stations (CA), and stations (nodes) 3.1, 3.2, 2.1, 2.2, 1.2, 1.1 are subscriber (AS). Station (node) 1 is designated as the main station (node).

Networks are assigned to the CA, which can be connected, and therefore from them and synchronized, lower-level stations. An AS is a station that is connected to a higher station (CA) but does not have any lower stations connected to it. The CA, in turn, can be connected to a higher-level CA (subordinate CA). In this case, for a higher level, it acts as a speaker.

Communication between the CA and slave stations (AS and CA) is carried out in a periodically repeating frame Tk.

An example of the organization of the frame shown in figure 2. Figure 2 shows: Tk is the frame duration, Tpd is the transmission interval of the DS, Tprm is the reception interval of the DS, TPS is the search and reception intervals of the sync code from the higher DS, Tpr is the transmission intervals of the higher DS, Tprm is the reception intervals of the higher CA. The durations of the intervals can be chosen arbitrary and, in the general case, are not equal to each other. During one frame, the CA exchanges data (transmission and reception) with all slave stations. A CA frame consists of exchange intervals with all subordinate stations, and also includes exchange / synchronization intervals with a higher CA. An AS frame consists of exchange / synchronization intervals with a superior CA and may include standby intervals (no exchange or synchronization).

The proposed network works as follows. In the transmission medium, a multi-level hierarchical communication system is organized. Information is transmitted in packets. The information part of the package includes control headers (preamble) and user information. The preamble contains a well-known code with fairly high correlation properties. This code (sync code) is used throughout the network. It is possible to use several sync codes both at one and at different levels. The information includes the identifier of the station (node) transmitting this packet. It is possible to use various sync codes to identify stations (nodes).

The distribution of the time-frequency resource is made as follows - a set of frequencies is allocated to each CA and the frame structure is determined, which is sufficient for organizing communication with subordinate speakers and synchronizing with a higher-level CA. For a CA that does not have a superior CA, time slots for synchronization with a higher level are not allocated in the frame. When executing the synchronization algorithm with a higher CA defined for the AS or CA, work is carried out in the corresponding frame intervals at the frequencies of the higher CA.

The sync search interval Tps is the interval during which the station searches for and receives the sync code from the upstream DS in the communication channel. When receiving the sync code and, if necessary, the information part of the packet on the subordinate CA, a decision is made to synchronize its own exchange cycle with the higher-level exchange cycle (adjusting the exchange cycle of the subordinate CA to the exchange cycle of the higher CA in order to match the corresponding exchange intervals).

Synchronization with a superior CA on a subordinate CA can be performed:

- in the intervals specially allocated for this — both intended for exchange with a higher CA (before the detection of the sync code — shown in FIG. 2), and additionally allocated for the search for sync code;

- in free (not occupied for exchange with the AU and subordinate CA) intervals;

- in the Tprm intervals, if at the beginning of this slot no preamble was found from the corresponding AS or subordinate CA (the interval is not busy - the corresponding AC or subordinate CA is not active);

- in Tpr intervals, if it is known that the corresponding AS or subordinate CA is not active.

For the simultaneous operation of all levels of the communication system and the organization of interaction between all stations, it is necessary that the cycles of exchanges of higher and lower CAs be synchronized. For this, a complex combination of communication algorithms is used, described below. For the communication system shown in figure 1, the proposed algorithms can be distributed as follows:

- for all speakers of levels 1, 2, 3, an algorithm for organizing a communication network for speakers is used;

- for a level 2 CA, an algorithm for organizing a communication network with a frame of variable duration is used;

- for a level 3 CA, a fixed-frame communication network organization algorithm is used;

- for a level 4 CA, an algorithm is implemented in a predetermined frame structure without synchronization to higher levels.

Station synchronization in the network is carried out by the synchronization algorithms described earlier.

The proposed communication network may use various means of signal transmission, for example, radio, wireline communication or fiber optic communication. A prerequisite is the existence of a connection between the CA and the subordinate CA and AS.

In the proposed network, in contrast to the prototype device, the parameter that determines the synchronization algorithm is not a distance class, which is a function of the distance to the main node, but a hierarchy level assigned to each node, and therefore, the frame structure and frequency range (for radio communication). It is assigned at the stage of network deployment and is not subject to change during operation.

The technical result is as follows:

- there is no need to establish a connection - a device that recognizes its address simply receives a message, while all other devices ignore it;

- improving the efficiency of the use of hardware resources (network operation is carried out by one receiving and transmitting device;

- there is no need for simultaneous work on reception and transmission), which reduces the complexity, dimensions, power consumption and cost of the system;

- increasing the efficiency of using the frequency resource with a guaranteed bandwidth for each subscriber (no special control channels are required);

- increasing the stability of the communication system to failures, including intentional (operability of the communication system and its parts in the event of failure of individual nodes, ensures the stability of the communication system to failures, equipment failures and interference in the communication channel);

- providing a hierarchical (multi-level) communication system with the possibility of individual levels and parts of the network working autonomously with integration into a common network when other hierarchical levels or parts of a communication system are activated (turned on, restored, etc.).

Thus, in the proposed communication network, the remote class RDC (0) is excluded, the remote classes RDC (1), RDC (2), RDC (3) are replaced by Network 3, Network 2 and Network 1, respectively; Changed the way network synchronization dynamic network reconfiguration is excluded; An assignable network structure has been introduced.

A device is known for two-way communication with time division of channels with a mobile station in a telecommunication network [5], in which the prevention of conflicts between transmissions on the uplink and downlink is achieved by identifying the time segment used in the first direction of communication and making a choice on its basis for the second communication direction of such a time segment that will not overlap with the time segment used in the first communication direction.

The disadvantages of this device include:

- lack of guaranteed bandwidth provided to each subscriber (a request for the allocation of additional intervals for exchange may be rejected);

- the presence of only two levels of the hierarchy (one main, or base, station and its subordinate stations).

A known radio interface for a duplex communication system with a time seal with wireless communication [7], in which for each communication connection a pair of time slots from a predetermined number of time slots is selected so that the interval between the time interval of the forward link and the time interval of the reverse link equal to the fraction of the duration of the temporary compaction frame.

The disadvantages of this interface include:

- the need for dynamic configuration and reconfiguration of the network;

- lack of ambiguity in the hierarchical construction of the network - the subordination of stations depends on environmental conditions and can change during operation.

Closest to the technical nature of the proposed is a network node of a wireless network [8], adopted as a prototype.

Figure 6 presents a block diagram of a prototype device, where it is indicated: 14 ... 17 - electrical devices, 18 - bus, 19 - interface circuit, 20 - protocol device, 21 - modem, 22 - high-frequency (HF) circuit, 23 - antenna.

The prototype device includes several electrical devices 14-17 and the bus system 18. Electrical devices 14-17 exchange useful data, control data, and synchronization data via bus 18.

The interface circuit 19 of the radio device 13 is connected to the bus 18 and receives the data intended for the radio device 13 from the bus 18 and provides this data, possibly after adapting the format to the protocol device 20 of the radio device 13. The interface circuit 19 supplies the data output by the protocol device 20 to the bus 18. The radio 13 also includes a modem 21, a high frequency circuit 22 and an antenna 23. The high frequency circuit 22 supplies the data received by the antenna 23 to the protocol device 20 through the modem 21.

The protocol device 20 generates packet blocks from the data supplied by the interface circuit 19, or generates data suitable for processing by the interface circuit from the packet blocks supplied by the modem 21. In addition to the received data, the packet block also contains control information that is generated by the protocol device 20. The protocol device 20 uses protocols for the ULF level (logical channel control) and the MAC layer (medium access control). The UDS layer controls multiple access to the radio environment of the radio device 13, and the ULC layer controls flow and errors.

A synchronization channel is used to transmit the synchronization pattern P (i).

Measurement of reception quality is performed by modem 21. The measurement procedure, however, is controlled by its associated protocol device 20. Moreover, the protocol device 20 compares the measurement results with a threshold value and performs appropriate control operations depending on the comparison result.

The protocol device 20 at the secondary network node evaluates the pulse waveform supplied by the associated correlator to determine the timing.

The disadvantages of the prototype device are:

- lack of a fixed hierarchy between radio stations;

- the need for dynamic reconfiguration of the network during operation;

- inefficiency in the use of channel bandwidth due to the cost of periodic transmission of service information about the network configuration;

- the need for a separate synchronization channel;

- Work only in a wireless network.

The task is to create a node for a network with several levels of hierarchy with guaranteed bandwidth for each subscriber and minimum hardware requirements, supporting synchronization with a designated higher-level communication node and providing synchronization for downstream nodes.

To solve this problem, a physical interface device, a medium access device, an interface device consisting of n (n≥1) interfaces are connected to a network node containing a protocol device, an interface, and a terminal device, according to the invention, and n terminal devices are connected to them respectively.

A block diagram of the proposed network node is shown in Fig. 7, where it is indicated: 100 - medium access device, 101 - logical channel device, 20 - protocol device, 102 - interface device, 103 - terminal devices, 104 - physical interface device.

The proposed device comprises a series-connected device of the physical interface 104, a device for accessing the medium 100, a device of the logical channel 101, a protocol device 20, a device of interfaces 102. The corresponding terminal devices 103 are connected to the device of interfaces 102.

The proposed device operates as follows.

When transmitting information, information from terminal devices 103 is fed to an interface device 102. In the interface device 102, the incoming information is converted, if necessary, to a digital form, buffered (accumulated) and, in the corresponding representation, fed to the protocol device 20. In the protocol device 20, the incoming information is distributed on the corresponding blocks of information (buffers) that are received on the device of the logical channel 101. The device of the logical channel 101 provides flow control and error . In the device of the logical channel 101, the incoming information blocks are distributed according to the logical buffers corresponding to each communication direction (subscriber), from where, in accordance with the operating algorithm, they are transferred to the medium access device 100. The medium access device 100 provides an algorithm for multiple access to the information transmission medium. Correspondingly formed data blocks enter the transmission medium through the physical interface device 104.

When receiving information, the medium access device 100 through the physical channel device 104 is synchronized and receives data from the transmission channel.

The data received by the device for accessing the medium 100 enters the device of the logical channel 101, where it is distributed to the corresponding information blocks, which are received by the protocol device 20. In the protocol device 20, the received information according to the implemented protocol is distributed into data sequences (streams) corresponding to each terminal device 103. Data streams are buffered and fed to the interface device 102. In the interface device 102, the data is converted into the corresponding signals (including into analog, if necessary) and enter terminal devices 103.

Thus, in the proposed network node, the radio device is replaced by a physical interface device and a medium access device, the protocol device is removed from the radio device in a separate unit, a logical channel control device is inserted between the medium access device and the protocol device, the interface circuit is replaced by an interface device, electrical devices replaced by terminal devices, bus excluded.

The medium access device 100, the logical channel control device 101, and the protocol device 102 or their separate parts can be implemented in one of the following ways:

- in the form of microprocessor devices (or as a single microprocessor device) with appropriate software, for example, a processor series TMS320VC5416 from Texas Instruments,

- in the form of a programmable logic integrated circuit (FPGA), with appropriate software, for example, Xilinx FPGA XCV400,

- in the form of specialized microcircuits.

The technical result is the expansion of functionality:

- as a transmission medium using a radio, wired or fiber optic network;

- there is no need for a host to establish a connection - a host that recognizes its address receives a message, while all other hosts ignore it;

- increasing the efficiency of the use of hardware resources of a network node - network operation is carried out by one receiving and transmitting device (simultaneous work on receiving and transmitting is not required), which reduces the complexity, dimensions, power consumption and cost of network nodes;

- increasing the efficiency of using the frequency resource with a guaranteed bandwidth for each subscriber (no special control channels are required);

- increasing the stability of the system built on the proposed network nodes to failures (equipment failures and interference in the communication channel), failure of individual nodes ensures the operability of other network nodes;

- providing a multi-level reconfigurable communication system when using unified network nodes, the ability of the network nodes to work in separate levels and parts of the network autonomously with integration into a common network when other levels or parts of the communication system are activated.

Information sources

[1] Prokis John. Digital communication. - Per. in English / Ed. D.D. Klovsky. - M .: Radio and communication. 2000 .-- 800 s.

[2] Feer K. Wireless Digital Communications. Modulation and spreading methods. - Per. from English / Ed. V.I. Zhuravleva. - M .: Radio and communications, 2000 .-- 520 p.

[3] Sklyar, Bernard. Digital communication. Theoretical foundations and practical application. Ed. 2nd, rev .: Transl. From English. - M .: Publishing House "Williams", 2003. - 1104 p.

[4] RU 97107339 A, 05.27.1999.

[5] RU 2201035 C2, 2003.03.20.

[6] RU 2201034 C2, 1998.09.16.

[7] RU 2193280 C2, 2002.11.20 - a prototype for the method.

[8] RU 2233545 C2, 1999.10.11 - prototype for a network node.

Claims (17)

1. A synchronization method in a multi-level communication network based on time consolidation between mobile and / or stationary transceiver devices, the carrier frequencies predefined for the communication system being distributed over a number of time intervals with a predetermined duration so that the communication system can operate in duplex mode with time multiplexing, in time intervals and, accordingly, frequency ranges of the communication system, it is possible to simultaneously hydrochloric setting maximum predetermined amount bilateral communication connection in the forward and backward directions between the users of mobile transceiver devices or stationary transceivers communication system
characterized in that
communication is carried out in several hierarchically organized levels with synchronization of nodes of a lower level to a higher one;
a subordinate node is configured to connect subordinate nodes for which it is a superior;
each node is assigned a time interval for receiving and transmitting allocated to it;
the exchange between superior and subordinate nodes is carried out in a repeating frame, during which an exchange is made with all subordinate nodes;
transmission and reception time slots are pre-allocated in frames of each network layer;
subordinate nodes of the first level that do not have their own subordinate nodes, as well as subordinate nodes of other levels that do not have their own subordinate nodes, are synchronized to a higher node by searching and receiving a sync code at one of the preset frequencies for an interval exceeding the frame duration of a higher node with a subsequent periodic frequency change in the absence of reception of a sync code;
second-level subordinate nodes having their own subordinate nodes work with their subordinate nodes in a second-level frame of duration T2 different from the duration of a higher-level third level T3 frame, searching for a higher-level node's sync code at predetermined intervals with periodic changes in the sync-code search frequency at intervals, sufficient to detect the sync code, and with a change in the frame duration by T3 when detecting the sync code and synchronizing the exchange cycles;
subordinate nodes of the third level, having their own subordinate nodes, work with subordinate nodes, and the exchange intervals of this subordinate node and the parent node are distributed in such a way that for any mutual arrangement of the exchange cycles of the subordinate node, at least one sync code will be taken from the parent node for the duration of one exchange cycle, and after the synchronization code is detected, synchronization is carried out;
the superior node of the fourth level, having its own subordinate nodes and not having superior nodes, works with all subordinate nodes in a predetermined exchange cycle. 2. The method according to claim 1, characterized in that before starting work, at least one subordinate node having its subordinate nodes, during a time interval of at least the duration of the frame of the parent node, searches for the sync code from the parent node and, in If it is detected, it synchronizes with it. 3. The method according to claim 1, characterized in that the duration of the frames of nodes of various levels is selected as multiples, i.e. the duration of the frames of the parent nodes is chosen equal to the integer number of the durations of the frames of the subordinate nodes and, accordingly, the durations of the frames of the subordinate nodes are chosen equal to the integer number of the durations of the frames of the subordinate nodes. 4. The method according to claim 1, characterized in that the reception or transmission of data from a higher node is carried out at several time intervals for receiving or transmitting data, including from other slave stations. 5. The method according to claim 1, characterized in that the allocation of transmission intervals by the subordinate data node to the parent node is performed at the request of the parent node contained in the service data transmitted by the parent node. 6. The method according to claim 1, characterized in that the number of levels in the network can be ≥2. 7. The method according to claim 1, characterized in that the transmission medium uses a wired or fiber-optic network organized by the topology of the "bus", "star" or combined network topology, while the role of frequency separation is performed by separate network segments, switching between which carried out according to the described method. 8. A multilevel network containing many nodes, the network node, which is designated as the main network node, is intended to transmit the synchronization combination to all other network nodes, designated as secondary network nodes, while the secondary network nodes are intended to transmit the synchronization combination, each secondary node networks are designed to synchronize the received synchronization combination - sync code,
characterized in that
several hierarchically organized levels were introduced with synchronization of nodes of a lower level to a higher one;
the subordinate node has subordinate nodes for which it is a parent;
each node is assigned a time interval allocated to it / reception and transmission intervals;
the exchange between higher and subordinate nodes is carried out in a repeating frame during which an exchange is made with all subordinate nodes;
transmission and reception time slots are pre-allocated in frames of each network layer;
subordinate nodes of the first level that do not have their own subordinate nodes, as well as subordinate nodes of other levels that do not have their own subordinate nodes, synchronize to a higher node by searching and receiving sync code at one of the preset frequencies for an interval exceeding the frame duration of the higher node with a subsequent periodic frequency change in the absence of reception of a sync code;
subordinate nodes of the second - higher than the lower level, having their own subordinate nodes, work with their subordinate nodes in a second-level frame with a duration of T2 different from the duration of a higher-level frame of the third level T3, with a search for the sync code of the higher node in a predetermined interval / intervals with by periodically changing the sync code search frequency at intervals sufficient to detect the sync code, and with changing the frame duration by T3 when the sync code is detected and synchronization iklov exchange;
subordinate nodes of the third level, having their own subordinate nodes, work with subordinate nodes, and the exchange intervals of this subordinate node and the parent node are distributed in such a way that for any mutual arrangement of the exchange cycles of the subordinate node, at least one sync code will be taken from the parent node for the duration of one exchange cycle, and after the synchronization code is detected, synchronization is carried out;
the superior node of the fourth level, having its own subordinate nodes and not having superior nodes, works with all subordinate nodes in a predetermined exchange cycle. 9. The multilevel network according to claim 8, characterized in that before starting work, the subordinate node having its subordinate nodes, during a time interval of at least the frame duration of the parent node, searches for the sync code - the preamble, the parent node and, if it is detected , synchronizes with it. 10. A multilevel network according to claim 8, characterized in that the frame durations of nodes of different levels are selected as multiples, i.e. the duration of the frames of the parent nodes is chosen equal to the integer number of the durations of the frames of the subordinate nodes and, accordingly, the durations of the frames of the subordinate nodes are selected equal to the integer number of the durations of the frames of the subordinate nodes. 11. The multilevel network of claim 8, characterized in that the reception from the parent node is carried out at several time intervals for receiving or transmitting data, including from other slave stations. 12. A multilevel network according to claim 8, characterized in that the assignment of transmission intervals by the subordinate data node to the parent node is performed at the request of the parent node contained in the service data transmitted by the parent node. 13. A multilevel network according to claim 8, characterized in that the number of levels in the network can be ≥2. 14. A multilevel network according to claim 8, characterized in that a wired or fiber optic network is used as the transmission medium, while the role of frequency separation is performed by separate network segments, switching between which is performed by the physical interface devices of the corresponding node. 15. A network node comprising a protocol device, an interface and a terminal device, characterized in that the physical interface device, the medium access device and the logical channel device, the output of which is connected to the protocol device, the output of which is connected to the interface device, are introduced in series n (n≥1) interfaces to which n terminal devices are connected respectively. 16. The network node according to clause 15, characterized in that a wired or fiber optic network is used as the transmission medium, while the role of the frequency separation of the network levels is performed by separate network segments, switching between which is performed by physical interface devices. 17. The network node according to clause 15, wherein one of them is designated as the main network node, intended for transmission of the synchronization combination to all other network nodes, designated as secondary network nodes.

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