Method, system and nodes for network topology detection in communication networks

ES 2 396 014 T3

DESCRIPTION

Method, system and nodes for a network topology detection in communication networks

Technical field of the invention

The present invention relates to a network topology detection in communication network technology, particularly to a method, a network apparatus, a device and a computer-readable medium for detecting types of network topology in an environment of telecommunication network.

Background of the invention

This invention will enable wired or wireless mesh networks to detect the network topology of which they consist and provide a solution on how to select the best suitable operating mode.

This invention can be applied to the following fields of technology, WiFi and WiMAX network technology, ad hoc and mesh network technology, wireless sensor networks, routing and switching technology such as for example Ethernet, microwave technology.

Wi-Fi is the trademark for popular wireless technology used in home networks, mobile phones, video games, and other electronic devices that require some form of wireless networking capability. In particular, it covers the various technologies of the IEEE 802.11 standard (including the 802.11a, 802.11b, 802.11g and 802.11n standards).

WiMAX, which stands for Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides the wireless transmission of data using a variety of transmission modes, from point-to-point links to portable Internet access. The technology is based on the IEEE 802.16 standards.

3GPP LTE (Long Term Evolution) is the name for a project within the adjacent second generation partnership project to cope with future technology evolutions. Goals include improving spectral efficiency, reducing costs, improving services, using new spectrum and repurposed spectrum opportunities, and better integration with other open standards.

Integrating a multi-hop capability by implementing relay stations (RS) has become an important topic for wireless cellular communication such as WiMAX and LTE. For example, the IEEE standard has established a relay working group to introduce relay stations into systems based on the IEEE 802.16 standard.

The mesh network is a way to route data, voice and instructions between nodes. It allows continuous connections and reconfiguration around broken or blocked paths by jumping from node to node until the destination is reached. A mesh network is considered to be a randomly arranged set of wireless nodes that can configure connections to adjacent nodes without any special manual care required. The nodes will be configured in such a way as to configure optimal routings using routing schemes based on data link or network layer packets of the Open System Interconnection (OSI) reference model.

It may be necessary to set up a mesh configuration when nodes can be placed in a completely messy manner. This can happen during a configuration phase of a communication network or when node drops or links are broken randomly.

Mesh networks can be viewed as a type of ad hoc network. Mesh networks recover automatically: the network can still operate even when a node breaks or a connection malfunctions as it can happen that the entire set of nodes or a significant number of nodes are arranged in a more orderly manner. As a result, a very reliable network is formed. This concept is applicable to wireless networks and wired networks.

Wireless mesh networks are the most popular representatives of mesh architectures. Mesh nodes can also support multiple radio cards, each operating at a different example given frequency, code, or time slot.

Mesh routing and switching protocols are standardization topics, mainly in the IEEE 802.11 s and IEEE 802.16j standards.

A wireless ad hoc network is a decentralized wireless network. The network is ad hoc because each node is willing to forward data to other nodes, and therefore the determination of which nodes forward data is done dynamically based on network connectivity conditions. This is unlike wired networks where routers perform the routing task.

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A Wireless Sensor Network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to jointly monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion, or pollutants, at different locations.

Ethernet is a family of network technologies for local area networks (LANs). Defines various cabling and signaling standards for the physical layer of the Open Systems Interconnection (OSI) reference model, across network access media in the link layer media access control (MAC). data (DLL), and a common addressing format. Ethernet is standardized as IEEE 802.3.

Microwave radio transmission is a technology for transmitting digital and analog signals, such as long distance telephone calls and relaying television programs to transmitters, between two locations on a line of sight radio connection.

The networks are arranged in a daisy chain when each node is connected in series to the next. If a message is intended for a node on the line, each node forwards it in sequence until it reaches the destination.

By connecting the nodes arranged in a daisy chain at each end, a ring topology can be formed. An advantage of the ring is that the number of transmitters and receivers can be cut in half, since a message will eventually circulate throughout the ring. When a node sends a message, the message is processed by every node in the ring. If a node is not the destination node, it will pass the message to the next node, until the message reaches its destination. If the message is not accepted by any node on the network, it can travel around the entire ring and return to the sender.

EP000115476 by Hauenstein et. al., discloses a method for, eg, virtual local area network, constructing a topology database describing a network topology based on received topology descriptors reported by a central host.

In today's fixed and wireless communication networks there is more often a constellation in which the nodes forwarding data have connectivity to more than one or two adjacent nodes, allowing more than one option or choice for routing.

A typical example is a routed network in which one IP router has connectivity to many IP routers, so packets transferred from one peer end of a network to another peer end of the network may use different routings. across the network using different IP routers, in the extreme case for each packet.

Another example is an Ethernet network where packets can traverse different switches, hubs, or bridges in a Layer 2 network.

Whenever there is more than one choice of routes to choose from among the number of possible routes, the number of nodes involved is greatly expanded, but there may still be only one of these routes that is optimal in terms of QoS and reliability for each connection and only selecting the best possible routings for all connections will allow the entire network to run properly.

Finding smart algorithms is one of the most innovative areas in determining optimal routings, and there are many algorithms and methods on how to achieve them.

In routed networks there are different variations of routing protocols involved which can be classified into proactive routing protocols such as OLSR (optimized link state routing), reactive routing protocols such as DSR (dynamic source routing) and hybrid routing protocols. such as ZRP (zone routing protocols)

The algorithms behind are diverse and specialize in different use cases, each having its own advantages and disadvantages.

There are numerous ways how to best handle a path finding and mesh configuration. A prominent example of how to deal with both path finding and dynamic changes is the Hybrid Wireless Mesh Protocol (HWMP) as recommended by the IEEE 802.11s standard. This case involves a combination of proactive (long range) and reactive (local) routing protocol to better address mesh problems.

In the case of point-to-point wireless connections, even more techniques can be applied, such configurations typically being used for microwave links. In general, depending on the nature of the air interface, a carrier, a timeslot (time division multiple access) or a frequency (frequency division multiple access) is dedicated to a link.

However, it is considered that point-to-point connections should be used in static, manually configured environments, where highly dynamic systems are considered to be used in mesh or ad hoc network environments.

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Routing and path finding can be implemented in ad hoc or mesh networks in municipal networks, developing countries, new players setting up competitive access networks but also an industrial environment such as wireless metering, wireless metering and sensor networks.

Selecting the best possible routing is even more important if the nodes are connected through links where they can show instability or changing quality such as wireless links. In addition, additional challenges arise when connectivity between different nodes changes frequently, that is, because new nodes are added or removed, nodes move, or radio conditions change.

This is typical for so-called mesh networks and ad hoc networks, the wireless connection nodes are re-arranged occasionally so that the routings can change frequently. In this case, in addition to the known routing finding problem, the high dynamics problem becomes a priority.

Mesh technologies differ from state-of-the-art technologies by being very dynamic in terms of packet delivery and routing discovery, which may mean that each packet takes a different routing.

A typical example of a non-mesh technology can be different point-to-point connections, that is, nodes are interconnected by fixed links and all traffic from one edge of the network to another edge of the network will use fixed routes that are predefined by links fixed. A commonly used terminology for this type of configuration is "switched mesh" which indicates that a node can have connections for more than two additional nodes. However, the traffic will always use the same routes unless a link is broken.

"Switched mesh" is mainly used in static scenarios without any topology change where a real mesh is used in highly dynamic environments.

Resource usage, especially in the case of wireless telecommunication network environments, is extremely different for mesh and non-mesh use cases.

The use of mesh technologies in telecommunication environments requires per packet handling with frequent routing table updates, high mesh overhead, additional delay caused by mesh, but provides highly dynamic but self-healing capabilities.

The non-mesh telecommunication environment provides continuous link availability, stable quality of service (QoS), no or minimal delay, quasi-circuit-switched mode, and no or little flexibility.

This invention provides a method that allows to operate in an optimized topology mode once mesh systems are configured.

It may be advantageous not to use any mesh mechanism where the networks are daisy chained since traffic can only be forwarded along the chain therein. The use of meshing or routing schemes does not necessarily provide the most efficient network connection for these scenarios. Instead, it may be better to configure fixed point-to-point connections, so that the spare air interface resource can be better utilized.

There are also other configurations that provide for an air interface usage other than a typical mesh and it may be advantageous to use the best suitable configuration.

But before the best suitable mode can be employed such as mesh, non-mesh, circuit switched or routed, the telecommunication network can partly or totally recognize what kind of network topology it will apply to it. The task of the present invention is the detection of a type of network topology and the employment of an appropriate network topology mode in a telecommunication network environment.

Document BHATNAGAR A ET. AL .: “Layer net: a new self-organizing network protocol” 19900930; 19900930 19901003, September 30, 1990 (09-30-1990), pages 845-849, XP010002890, describes a self-organizing multi-hop radio network that can create its own topology and transmission schedules in a dynamic and distributed way.

Document US-A-5 732 086 (LIANG SONGCHYAU S [US] ET. AL.) Of March 24, 1998 (03-24-1998) describes a multinode network that manifests a changing topology of individual data processing nodes .

Summary of the invention

According to an exemplary embodiment of the present invention, a network apparatus, device, method, and computer-readable medium are provided for detecting types of network topology in a telecommunication network environment.

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The term "network appliance" can comprise any appliance in a network, which can comprise a fixed locally installed appliance and a mobile appliance and can comprise several devices. A device can be equipped with software and hardware that power the device that acts as a node in the telecommunication network. A node could be an access node such as a base station, a network controller, a relay station or an access point, a switching node, a fixed or mobile terminal, a computer equipment or a server.

The telecommunication network is considered by way of example as a set of randomly arranged wired or wireless nodes that can configure connections to adjacent nodes without any special manual care required. The nodes can be configured so that optimal routings can be configured using packet-based routing schemes on a data link or network layer of the Open Systems Interconnection (OSI) reference model.

According to an exemplary embodiment of the present invention, in a wired or wireless telecommunication network, nodes can be arranged and negotiated optimal paths for data forwarding after power-up or after network changes such as reconfiguration, increase or failure.

According to an exemplary embodiment of the present invention, wireless and wired line mesh networks can be enabled to detect the network topology of which they consist and a solution can be provided of how to select the best suitable operating mode.

When configuring a mesh configuration, it can happen that the entire set of nodes or a significant number of nodes are arranged in a more or less orderly manner. According to a further exemplary embodiment of the present invention, a daisy chain environment can be detected and thus fixed point-to-point connections can be configured so that spare air interface resources can be better utilized.

According to a further exemplary embodiment of the present invention, a configuration may be decided, which may provide for a use of the air interface resources different from the typical mesh, for parts of or the whole of the telecommunication environment and the best may be configured. suitable configuration such as a daisy chain or a ring configuration.

According to an exemplary embodiment of the present invention, the object of the present invention is achieved by three different technical phases: initiation of network topology discovery, autonomous evaluation of discovery probes, autonomous switching to the appropriate network topology mode .

Network topology discovery can be initiated when a node or multiple nodes discover a change in the system that can occur when an adjacent node has disappeared, a new adjacent node has been inserted, the link quality has changed, the volume of traffic or has received a discovery message from an adjacent node. The solution for topology detection can be applied in voice and data network environments. In particular, it can be applied in fixed and wireless environments.

The topology discovery procedure can evaluate the discovery probes autonomously in the second phase and can propose a best suitable network topology mode based on its analysis and can communicate it to other nodes.

The resulting network topology decision and the switch to an appropriate network topology mode can be based on a list of node proposals received by additional nodes during the second phase.

According to an exemplary embodiment of the present invention, the object of the present invention is achieved by a node having means to perform the three different phases: network topology discovery initiation in which a node can send a discovery probe, an autonomous evaluation of discovery probes in which a node can analyze the results of discovery probes and can send a proposal that comprises a topology mode network, and autonomous switching to an appropriate network topology in which at least one or each node can switch to an appropriate network topology.

According to an exemplary embodiment of the present invention, a node of the plurality of nodes can send a message comprising a discovery probe for at least one of the additional nodes, can send to at least one of the additional nodes a message comprising a proposed network topology of operation, and may have means for switching to an appropriate network topology mode.

According to an exemplary embodiment of the present invention, the method for detecting network topology types in a telecommunication network environment is characterized by an initiating node that detects its network topology by broadcasting discovery probes to adjacent nodes, receiving results from a discovery probe from at least one of the nodes of the telecommunication network and sending to at least one additional node a first information comprising a proposed network mode.

In a telecommunication network environment, where the nodes that forward data may be arranged in a

ES 2 396 014 T3 more or less randomly, the nodes can detect if they are arranged completely disordered as an example given in a mesh topology or if they can be arranged in part or in whole according to a specific network topology as an example given in a daisy chain topology that allows easier and more efficient use of forwarding resources and allowing even flexible paths as an example ring topology. Network topology detection can occur by broadcasting a discovery probe to adjacent nodes which can add information about themselves and their adjacent nodes and forward it to other adjacent nodes.

According to an exemplary embodiment of the present invention, the discovery probe can be sent back to the initiating node by a network edge node in which an edge node is a node that can serve as an egress to the network. principal.

According to an exemplary embodiment of the present invention, the discovery probe can be sent back to the initiating node by an additional node in the network where an additional node is a node that has more than two adjacent nodes.

According to an exemplary embodiment of the present invention, the initiator node may further comprise the functionality to analyze the discovery probe received from at least one of the nodes of the telecommunication network, and may calculate the proposed network mode.

As a result of the network topology detection of the present invention, nodes can apply optimized resource usage of network topology such as packet routing for a mesh or point-to-point topology for a daisy chain or in-line topology. ring.

Since each node of the plurality of nodes can perform this procedure, each node of the telecommunication network can have a list comprising information from the adjacent node of a part or all of the telecommunication network.

The second phase comprises an autonomous evaluation of discovery probes. Each node of the plurality of nodes can analyze the list comprising node information of a part or all of the telecommunication network and can propose a best suitable topology mode according to its analysis and can communicate it to at least one additional node. In a further exemplary embodiment of the present invention, the proposed network topology mode can be communicated to all additional nodes.

According to an exemplary embodiment of the invention, a node of the plurality of nodes may further receive the proposed network topology mode from at least one of the additional nodes and may switch to an appropriate network topology mode of operation depending of the proposed network topology of at least one of the additional nodes, in particular one of the adjacent nodes.

In accordance with an exemplary embodiment of the present invention, the resulting network topology decision and switching to an appropriate network topology mode may be based on a list of mode proposals received from at least one additional node.

In a further exemplary embodiment of the present invention, each node in the telecommunication network may have a list comprising the proposed network topology of all nodes in the telecommunication network.

According to a further exemplary embodiment of the present invention, the network topology modes provided may be classified and the appropriate network topology mode of operation may result in the least classified mode if one or more proposed network topology modes of the adjacent nodes differ from the proposed network topology mode itself.

According to a further exemplary embodiment of the present invention, the resultant which is the final network topology decision can be based on a least common denominator principle in which the telecommunication network system or parts thereof can operate in the proposed mode according to the list of mode proposals when all nodes propose the same mode and the telecommunication network system or parts thereof can operate in the least classified mode when one or more nodes differ from their proposed network topology.

Since all nodes can communicate their proposed network topology to the rest of the nodes, each node can switch to the appropriate mode individually without any additional communication since the rules for a decision are unambiguous for all nodes after the principle of denominator minus common.

According to an exemplary embodiment of the present invention, the appropriate mode of operation can result in a daisy chain mode and the nodes can use at least two different radio carriers.

In accordance with an exemplary embodiment of the present invention, an additional node may receive a discovery probe from an initiating node, may analyze its connections to adjacent nodes, and may add information about connectivity to its adjacent nodes to the probe. discovery.

In accordance with an exemplary embodiment of the present invention, an additional node can broadcast a probe of

ES 2 396 014 T3 discovery to its adjacent nodes depending on the result of its connectivity analysis.

According to a further exemplary embodiment of the present invention, the result of the analysis may cause the additional node to be able to have connectivity of a certain quality to two adjacent nodes and to send the discovery probe to at least one additional node in the network. telecommunication.

According to a further exemplary embodiment of the present invention, the telecommunication network may belong to a mesh network environment.

According to an exemplary embodiment of the present invention, a daisy chain operation method may be provided in which nodes skip their direct adjacent nodes and forward data to the next node instead of forwarding it to their direct adjacent nodes.

In accordance with an exemplary embodiment of the present invention, a method may be provided for operating a "daisy chain" type of network topology in a telecommunication network environment characterized by a first node, a second node, a third node, a fourth node and a fifth node that have the ability to use at least two different radio carriers, a second node being adjacent to the first node and a second adjacent node, a fourth node being adjacent to a third node and a fifth node, and wherein a third node forwards data directly to a first node using a first radio carrier, a fifth node forwards data directly to the third node using a second radio carrier and a second node forwards data directly to the fourth node using a third radio carrier.

In accordance with a further exemplary embodiment of the present invention, a novel daisy chain procedure may be provided in which data can be forwarded without interference to adjacent nodes. This can be achieved when three individual carriers are used which can be arranged in a corresponding way. According to a further exemplary embodiment of the present invention, the nodes can use up to three different radio carriers that can be separated by frequency, by time or by code.

According to a further exemplary embodiment of the present invention, each node may have the ability to operate on at least two of three carriers in parallel.

According to a further exemplary embodiment of the present invention, each node may be provided as a WiFi access point with directed or sectorized antennas pointing towards its eastern and western adjacent nodes.

According to a further exemplary embodiment of the present invention, carriers may be provided in accordance with the IEEE 802.11b / g standard.

According to a further exemplary embodiment of the present invention, each node can skip its direct adjacent node as long as the mode of operation is a normal mode because no node can fail. The normal operating mode can employ a frequency reuse of three to avoid interference.

According to a further exemplary embodiment of the present invention, each access point may use specific service set identifiers (SSID), the service set identifier of the forwarding data may be associated with the next adjacent node and not the next node. jumped in order to ensure proper associations.

According to a further exemplary embodiment of the present invention, the traffic being fed may be generated locally at the node where the node may be an access point.

When in normal operation, a configuration may apply with each access point a forwarding of traffic from its adjacent nodes along the chain while feeding on locally generated traffic at the access point. In normal operation mode, all access points bypass their direct adjacent nodes employing a frequency reuse of three to avoid interference.

According to a further exemplary embodiment of the present invention, an operational method can be provided by adding flexibility to the daisy chain system in which direct adjacent nodes can take on the role of failed nodes.

In accordance with a further exemplary embodiment of the present invention, the new operating procedure of a daisy chain can fix the failure by a transparent flexibility mode in which direct adjacent nodes can take on the role of the failed node with respect to to adjacent nodes effected in such a way that they may appear to be working closer to the failed node relative to them. It is not necessary for the affected direct adjacent node to realize that its forwarding node has failed as the direct adjacent nodes of the failed node can take on their role.

In accordance with another exemplary embodiment of the present invention, the new operating procedure of a daisy chain can fix the fault using a non-transparent flexibility mode in which adjacent nodes

Direct ES 2 396 014 T3s will communicate with affected nodes and negotiate future reuse of air interface resources.

According to a further exemplary embodiment of the present invention, a mode of operation can be provided for daisy chain systems that allow high overall throughput while still providing high flexibility characterized by nodes skipping their direct adjacent nodes, allowing direct adjacent nodes act as flexible nodes operating in two modes, one that leaves affected nodes unaware of a failed node, and one that actively involves affected nodes.

According to an exemplary embodiment of the present invention, a method may be provided for operating a type of daisy chain network topology in a telecommunication network environment characterized by a first node that can be affected, a second node that can be adjacent, a third node that can be the detection node, a fourth node that can be the second corresponding adjacent node and can be the one that has failed, and a fifth node that may be the corresponding second affected node. The third node which can be the detection node, can work as follows: the third node can detect a link failure for the fourth node, the third node can send a link failure detection to the fifth node and can establish a link failure detection. transparent transmission to the fifth node. Establishing a transparent transmission for the fifth node may be characterized in that it receives an acknowledgment message of a link failure detection message from the fifth node and switches to a transparent flexibility mode. The transparent flexibility mode can be characterized by receiving traffic from the second node on a third radio bearer and forwarding traffic from a third node to a fifth node.

According to a further exemplary embodiment of the present invention, a third node may further comprise: detect a link failure for the fourth node, send a link failure detection to the fifth node, and establish non-transparent transmission on the fifth node, the non-transparent transmission in a third node being able to be characterized in that it receives an acknowledgment message with respect to the link failure detection message of the fifth node and switches to a non-transparent flexibility mode of operation in which the switching takes place sending to a second node a message comprising information about switching to a non-transparent flexibility operation.

According to a further exemplary embodiment of the present invention, the method comprises negotiating which carrier is used to forward the data between the first node and the third node, negotiating which carrier is used to forward the data between the third node and the fifth. node, and negotiate which carrier is used to forward the data between the second node and the fourth node.

According to a further exemplary embodiment of the present invention, the failure of a node can be detected by an adjacent node. The detection node can report its suspicion to the second corresponding adjacent node of the failing node and can indicate that by design it can handle a transparent flexibility mode, a non-transparent flexibility mode, or both transparent and non-transparent flexibility mode .

According to a further exemplary embodiment of the present invention, failure of a node can be detected by stopping receiving signals.

According to a further exemplary embodiment of the present invention, a node adjacent to a failing node can have up to three radio headers that can provide handling of up to three carriers in parallel.

According to a further exemplary embodiment of the present invention, the corresponding second adjacent node of the failing node may search for the failing node upon receipt of the message from the detection node and may acknowledge its unavailability. The second corresponding adjacent node of the failing node may be of the same design and therefore may be of the same type as the detection node and may suggest using the transparent flexibility mode.

According to a further exemplary embodiment of the present invention, the adjacent detection node of the failing node may have received an acknowledgment message from the second corresponding adjacent node of the failing node, it may have sent an acknowledgment message to the second corresponding adjacent node and then both nodes can switch to a transparent flexibility mode.

According to a further exemplary embodiment of the present invention, nodes operating in a transparent flexibility mode can continue to forward traffic to or from their next node and these nodes can leave the radio configuration unchanged.

Furthermore, both nodes, the detection node as well as the corresponding second adjacent node of the failing node, can now provide an air interface to the affected nodes that is formed in exactly the same way as the failing node did. The adjacent discovery node can use the SSID of the failing node with respect to its still operating adjacent node and can use the same carrier as its direct adjacent node did with respect to the failing node.

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Consequently, the second corresponding adjacent node of the failing node can use the SSID of the failing node with respect to its still operating adjacent node and can use the same carrier since its direct adjacent node can be used with respect to the failing node. In this way, it is not necessary for the two affected nodes to realize that their forwarding node was replaced by the two directly adjacent nodes of the failing node. The behavior of nodes operating in transparent flexibility mode can be transparent to adjacent affected nodes. The affected adjacent nodes do not need to change their operating mode.

According to a further exemplary embodiment of the present invention, direct adjacent nodes can negotiate non-transparent flexibility mode and both detecting nodes of the failing node can send a message to the corresponding second adjacent node, both direct adjacent nodes can report to the corresponding affected nodes about the failing node. The affected nodes acknowledge receipt and establish a non-transparent transmission. According to a further exemplary embodiment of the present invention, the same carrier may be used between direct adjacent nodes of the failing node and the affected nodes as used between the affected nodes and the failing node to avoid interference.

According to another exemplary embodiment of the present invention, an affected node that forwards or receives data to the failing node can detect the failing node and can inform the direct adjacent node of the failing node.

According to another exemplary embodiment of the present invention, the nodes may provide different radio resource capabilities. A mixed operation of nodes supporting a single carrier and nodes supporting a multi-carrier can be provided.

According to another exemplary embodiment of the present invention, the method of operation may be in a "daisy chain" network topology mode and may be applied to any existing air interface operating in a licensed or unlicensed band.

According to an exemplary embodiment of the present invention, a communication node for detecting network topology types in a telecommunication network environment may be characterized in that it detects its network topology by broadcasting a discovery probe to adjacent communication nodes, receiving results from the discovery probe from at least one of the adjacent communication nodes and sending to at least one of the adjacent nodes a first information comprising a proposed network mode.

According to an exemplary embodiment of the present invention, a network apparatus in a telecommunication network may comprise at least a first node, a second node, a third node, a fourth node, and a fifth node connected in sequential order to the next one. characterized in that it operates in a daisy chain network topology mode, it has the ability to use at least two different radio carriers, the third node being adjacent to the second node and the fourth node, the third node forwarding data directly to the first node operating on a first radio carrier and the fifth node forwarding data directly to the third node operating on a second radio carrier, the third node detecting a link failure for the fourth node and sending a link failure detection to the fifth node, the third node receiving an acknowledgment message with respect to the link failure detection message and the third node having means for establishing a transmission to the fifth node.

According to a further exemplary embodiment of the present invention, a third node and a fifth node adjacent to a fourth node take on the role of a fourth node when it detects the link failure for the fourth node.

According to a further exemplary embodiment of the present invention, the role of the fourth node can be adopted by the third node and the fifth node such that it appears as the fourth node transparently to the second node and the sixth node, directly adjacent to the fifth node.

According to a further exemplary embodiment of the present invention, the role of the fourth node may be adopted such that the second node and the sixth node appear non-transparently as the fourth node.

According to a further exemplary embodiment of the present invention, the nodes may be WiFi or WiMAX access points or nodes of the long-term evolution technology.

According to a further exemplary embodiment of the present invention, a node may operate as an egress node having access to the main data telecommunication network.

According to a further exemplary embodiment of the present invention, the information list can be analyzed by each node and the best suitable network topology mode can be derived from the results of the analysis.

According to a further exemplary embodiment of the present invention, the analysis results may be communicated to the rest of the nodes or part of the nodes of the telecommunication network system.

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According to a further exemplary embodiment of the present invention, all nodes can communicate their proposal to all additional nodes and each node can switch to the appropriate network topology mode individually without further communication.

According to a further exemplary embodiment of the present invention, the rules for the decision may be unambiguous for all or part of the nodes. The node can follow the least common denominator principle.

Exemplary embodiments of the present invention will now be described with reference to the following drawings.

Brief description of the drawings

Figure 1 shows an exemplary embodiment of a telecommunication network, in particular a mesh network having a plurality of comprised nodes.

Figure 2 shows an example where the nodes are arranged in a sequential manner (daisy chain).

Figure 3 shows the relationship to adjacent nodes depending on the quality of the connection.

Figure 4 shows different types of network topology.

Figure 5 shows an exemplary message flow between nodes during the network topology detection phase of the present invention.

Figure 5a shows an exemplary message flow between nodes during the initiation of the network topology discovery phase, the autonomous network topology evaluation phase, and the autonomous network topology switching phase hereof. invention.

Figure 6 shows an exemplary embodiment of a discovery probe that may be formatted as shown in the present invention during the initiation phase of network topology discovery.

Figure 7 shows an exemplary embodiment of a proposed network topology that can be configured as shown in the present invention at the end of the discovery procedure.

Figure 8 shows another exemplary embodiment of a proposed network topology mode that can be configured for a ring configuration as shown in the present invention at the end of the discovery procedure.

Figure 9 shows an exemplary embodiment of a discovery probe that may be formatted in a completely messy manner as shown in the present invention during the network topology discovery initiation phase.

Figure 10 shows another exemplary embodiment of a proposed network topology mode that can be configured for a mesh configuration as shown in the present invention at the end of the discovery procedure.

Figure 11 shows another exemplary embodiment of a decision matrix that can be used for final network topology decision as shown in the present invention.

Figure 12 shows an exemplary embodiment of the present invention, comprising a specific operation of a daisy chain configuration in which direct neighbor nodes are bypassed when data is forwarded.

Figure 13 shows an exemplary embodiment of the present invention, in which the nodes discover the breakdown of a direct neighbor node.

Figure 14 shows an exemplary embodiment of the present invention, comprising a transparent flexibility mode and corresponding handling of a failover.

Figure 15 shows an exemplary embodiment of the present invention, comprising a non-transparent flexibility mode and corresponding handling of a failover.

Detailed description

To further clarify the objects, technical schemes and advantages of the present invention, the present invention is further described in detail with reference to the accompanying embodiments and drawings. It is necessary to indicate that the embodiments described in this case are merely for the purposes of illustration of the present invention; they are not to be construed as limiting the present invention.

Figure 1 shows an exemplary embodiment of a communication network, in particular a mesh network

ES 2 396 014 T3 comprising nodes a, b, c, d, e. This is a typical setup for a wireless mesh environment. The nodes of the network communicate with each other, using a common transmission medium, for example a common fixed wired line or a common radio frequency. Dashed lines connect adjacent nodes to each other, in other words those nodes, which can communicate directly with each other. Node a is adjacent to nodes b, c, d and e, node b is adjacent to nodes a, c and e, node c is adjacent to nodes a, b and d, node d is adjacent to nodes a, c and e, node e is adjacent to nodes a, b, and d. The invention is preferably implemented in larger networks as shown in figure 1.

After initialization, these nodes will be arranged and negotiated the optimal paths for data forwarding. The layout result can be a mesh mode when nodes are configured in a completely random fashion or daisy chain when nodes are subsequently ordered as shown in Figure 2.

However, even when the connections between nodes are broken, it may happen that the entire set of nodes or a significant number of nodes are arranged in a more orderly manner again.

Figure 2 shows an example where the nodes are daisy-chained when each node is serially connected to the next and the traffic can only be forwarded along the chain. Dashed lines connect adjacent nodes in the chain to each other, in other words those nodes, which can communicate directly with each other. Node a is adjacent to node b, node b is adjacent to nodes a and c, node c is adjacent to nodes b and d, node d is adjacent to nodes c and e, node e is adjacent to node d. Node d may have an egress that interfaces with an adjacent communication network that could be an access point of another mobile network. The invention is preferably implemented in larger networks than that shown in figure 2.

For these networks as described by way of example for daisy chain scenarios, the use of meshing or routing schemes would be an effort that exceeds the desired goal. Therefore, it would be more advisable to configure the fixed point-to-point connections, so that the spare air interface resource can be better utilized.

There are even more configurations that foresee a different air interface use than a typical mesh and it seems to be very promising to always use the best suitable configuration.

Figure 3 shows the relationship to adjacent nodes in terms of quality with respect to their connection. Regardless of the air interface that is used and regardless of the network topology that is provided, a node can observe more than direct adjacent nodes. Adjacent nodes can be classified in terms of quality, for example signal-to-noise ratio (S / I) in the wireless case or bandwidth or bit error rate (BER) in the case of wired line connections. In the example of figure 3, node c can be connected to nodes b and d with a good signal-to-noise ratio (S / I) which is illustrated by the solid line c11 and c12 but node c can also be connected to the nodes a and e with poorer signal-to-noise ratio (S / I) illustrated by dashed lines c1 and c2. Node b can connect to nodes a and c with a good signal-to-noise ratio (S / I) illustrated by the solid line c10 and c11 but it can also connect to node d with a bad signal-to-noise ratio (S / I) , illustrated by the dashed line c3. Node d can be connected to node c and e with a good signal to noise ratio (S / I) illustrated by the solid line c12 and c13 but it can also be connected to node b with a bad signal to noise ratio (S / I), illustrated by the dashed line c3. In this terminology, node d may indicate nodes c and e as adjacent "S / I class 1" nodes and nodes b as adjacent "S / I class 2" nodes.

Figure 4 shows different types of network topology comprising a ring, daisy chain and mesh network topology mode. Multiple nodes (a, b, c, d, and e) can create a mesh network. In addition, one or more nodes can provide root node functionality that can be interconnected to a main communication network. In this example, node e will provide an egress from a root node functionality.

There can be many network topologies that warrant treatment of specific resources; however, in an exemplary embodiment of this invention mesh, daisy chain, and ring topologies are depicted.

For mesh mode, the conventional scenario is that nodes are configured in a completely random fashion and each node can communicate with a pair of adjacent nodes.

For daisy chain mode, nodes are ordered in a subsequent manner and traffic is forwarded along the chain, that is, from west to east from node a to node b to node c to node d to node e.

For ring mode, a specific case of daisy chain arrangement, however, alternative routings are possible either clockwise or counterclockwise.

Figure 5 shows the relationship with adjacent nodes in terms of quality with respect to their connection and an exemplary flow of messages between the nodes of the present invention. Regardless of the air interface that is used and regardless of the topology that is provided, a node can observe more than nodes

ES 2 396 014 T3 direct neighbors. Adjacent nodes can be classified in terms of quality, for example signal-to-noise ratio (S / I) in the wireless case, bandwidth or bit error rate (bEr) in the case of wired line connections. Similar to the example in figure 3, node c can be connected to nodes b and d with a good signal-to-noise ratio (S / I) which is illustrated by the solid line c11 and c12 but node c can also be connected to nodes a and e with poorer signal-to-noise (S / I) ratio illustrated by dashed lines c1 and c2. Node b can be connected to nodes a and c with a good signal-to-noise ratio (S / I) illustrated by the solid line c10 and c11 but it can also be connected to node d with a bad signal-to-noise ratio (S / I). Node d can be connected to node c and e with a good signal-to-noise ratio (S / I) illustrated by the solid line c12 and c13 but it can also be connected to node b with a bad signal-to-noise ratio (S / I ).

Node b can be the initiator node for a network topology discovery. Thus, node b can broadcast a message M1 comprising a detection probe to its adjacent nodes a and c. Node a can receive the message comprising the discovery probe of node a, detects that it has no additional direct adjacent node except node b from which the source message came, and sends back an M3 message comprising this information with relative to the initiating node b. Node c can receive the message comprising the discovery probe from node b, can add its adjacent node information to the discovery probe, and can forward the M7 message comprising the amended discovery probe information regarding node d and that node d may be the only direct adjacent node except for the initiating node b from which the source message came. When node d itself receives this message, it can add its adjacent node information to the discovery probe and can forward the m8 message comprising the amended discovery probe with respect to node e since node e may be the only adjacent node direct with the exception of node c from which the discovery probe came. The node e can receive the message comprising the discovery probe of the node d, can detect that it is an edge node and can send back the message M11 comprising this information with respect to the initiating node b. As an alternative to the message flow in this example, node c can now carry out its own investigation into its topology discovery and can send this information directly back to node b.

Node b can analyze discovery probe results from additional nodes and can broadcast an M5 message comprising a proposed network topology mode, relative to its adjacent nodes.

This procedure can be initiated from each node of the telecommunication network and therefore each node can broadcast a proposed network topology mode.

Figure 5a shows an exemplary message flow between nodes during the initiation of the network topology discovery phase, the autonomous network topology evaluation phase, and the autonomous network topology switching phase of the present invention. .

The initiation of the network topology discovery phase is already described in detail in figure 5 which comprises the message flow M1, M7, M8, M3 and M11. The nodes can have the same role as described in figure 5.

During the autonomous evaluation phase, the initiating node b can analyze the results of the discovery probe and can configure a network topology proposal based on results that are obtained from the additional nodes. At the end of this procedure, node b can send to additional nodes, node a, node c, node d and node e, the message M5 comprising a proposal for a network topology mode.

Node b may also receive from additional nodes a, c, d, and e, M20 messages comprising additional network topology proposals. The M20 message can be received after, before or at the same time that the node b can send its network proposal message M5.

The network topology types can be classified and the resulting topology operation type can be the least classified topology type if one or more proposed network topology types received from the additional nodes differ from the proposed topology type itself.

The initiating node b may send additional nodes a, c, d, and e, the M21 messages comprising the resulting type of network topology, and may switch to this type of network topology.

Figure 6 shows an exemplary embodiment of a discovery probe that may be formatted as shown in the present invention during the network topology discovery initiation phase. Each node can send these probes but will also be the receiver of other probes. If you are a receiver, you can fill in the requested information and forward the probe to other adjacent nodes but not back to the node that sent this probe. If the node has only one adjacent node (from which the probe was received) it will send the probe back to the originator since it is considered an edge node. If the node has more than two adjacent nodes it will no longer forward the probe but rather send it back to the originator, assuming it is on a completely messy and configured mesh, it is the best suitable mode. If it has only one adjacent node, it will assume that it is an edge node. When you have two adjacent nodes, it will send probes to both to derive their node status

ES 2 396 014 T3 adjacent. For descriptive purposes, the two adjacent nodes are indicated as the eastern and western adjacent node. After a while, each node will receive back the probes from its eastern and western neighbors with all the requested data filled in.

In a further exemplary solution of the invention, a node can classify its adjacent nodes according to signal-to-noise ratio (S / I) into "class 1 neighbors" of class 1 and "class 2 neighbors" of nodes. class 2 adjacent nodes. If the node has more than two class 1 adjacent nodes, it can no longer forward the probe but instead send it back to the originator, assuming it is in a completely messy and configured mesh, this is the best suitable mode. When you have two adjacent Class 1 nodes, you can send probes to both of them to derive their adjacent node status. After a while, each node can receive back the probes from its eastern and western neighbors with all the requested data filled in.

The exemplary embodiment of a probe may have a format comprising the information fields, originator, address, "I am", egress, "class 1 neighbors" and "class 2 neighbors". The originator field can contain an identifier of the originating node, the address field can contain the address the probe was sent to (east, west), the "I am" field can contain the node identifier that fills in its adjacent node information , the egress field can contain the information whether the node in question has access to a main communication network, the "class 1 neighbors" field can contain the identifiers of all adjacent nodes that have a connection that performs at least a certain quality criterion and the "class 2 neighbors" field can contain the identifiers of all adjacent nodes that have connectivity that does not meet certain quality criteria.

Probes for nodes a and b are discussed in a daisy chain configuration similar to the example in Figure 5.

Assuming a daisy chain configuration, node a would send a probe as shown in table 620 that goes east to node b, having filled in its adjacent node information which comprises setting the "I am" field aa, the field egress to no, the field "neighbors of class 1" b and the field "neighbors of class 2" to c. The receiving adjacent node b will then fill in its adjacent node information, which includes setting the "I am" field to b, the egress field to no, the "class 1 neighbors" field a and a and c and the "class 2 neighbors" field d and, then, send the probe to node c but not to node a since node a was the sender of this probe. This is accompanied by the daisy chain and the adjacent node c will then fill in its adjacent node information, which includes setting the "I am" field to c, the egress field to no, the "class 1 neighbors" field to and d and the "neighbors of class 2 ”a and e, then send the probe to the adjacent node d but not to node a since node a was the sender of this probe. The adjacent node d will then fill in its adjacent node information that includes setting the "I am" field to d, the egress field to no, the "class 1 neighbors" field to and e and the "class 2 neighbors" field to b, and then send the probe to node e adjacent but not node c since node c was the sender of this probe. The adjacent node e, which is the last node in the chain, will then fill in its adjacent node information, which includes configuring the "I am" field ae, the egress field to yes, the "class 1 neighbors" field d and the "neighbors of class 2 ”ac, and then send the probe back to string aa as e discovers that it is an edge node.

Node a will not send any probe going west since there is no adjacent node as it is an edge node.

The same procedure is carried out for all additional nodes, examples are shown in table 601, 602, 611, 612 of figure 6 for node b. Node b will send a probe going west to a and going east to c. The nodes a and e will send the probes back since they are the edge nodes.

When node b can send a probe as shown in table 601 going east to node c, it has previously filled in its adjacent node information which comprises setting the "I am" field to b, the egress field to no, the field "neighbors of class 1" a and c and the field "neighbors of class 2" a d. The receiving adjacent node b will then fill in its adjacent node information 6020 as shown in table 602. This is accompanied by the daisy chain until node e, which is the last node in the chain, then fills in its adjacent node information, which includes configuring the "I am" field ae, the egress field to yes, the "class neighbors" field. 1 "d and the" class 2 neighbors "field to c, and then send the discovery probe configuration as shown in table 611 back to the string aa as e discovers that it is an edge node.

Node b can send a probe going west to node a as shown in table 612. The adjacent receiving node a will then fill in its adjacent node information which comprises setting the "I am" field aa, the egress field to no, the "class 1 neighbors" field ab and the "class 2 neighbors" field ac, and then you can send the discovery probe back to b as it can discover that it is an edge node.

Figure 7 shows an exemplary embodiment of a proposed network topology mode that can be configured at the end of the discovery procedure when all nodes have returned their eastbound and westbound probes. The configuration table may have a format comprising the information fields, originator, response nodes, egress, suggested mode, and suggested routing. The

ES 2 396 014 T3 originator field can contain the identifier of the originating node, the response nodes field can contain the node identifiers of all nodes that respond with network topology discovery information, the egress field can contain the information of whether the node in question can have access to a main communication network, the suggested mode field may contain the proposed mode based on the network topology discovery information and the suggested routing field may contain forwarding data information.

Table 701 of Figure 7 shows the configuration for node a, which includes nodes a, b, c, d and e corresponding, the egress set to no for nodes a, b, c, d and set to yes for node e . Node a can configure the suggested daisy chain mode (7100) and according to the suggested routing (7010) configured for node a, node a can forward data to node b, then node b to node c, then node c to node d and then node d to node e. Node e can be the egress node to the main communication network of this chain.

Table 702 of figure 7 shows the configuration for node b, which includes the corresponding nodes a, b, c, d and e, the egress set to no for nodes a, b, c, d and set to yes for node e . Node b can configure the suggested suggested mode in the daisy chain and node a can forward data from node b to node c, then to node d and then to node e, according to the suggested routing in table 702. Node e can be the egress node to the main communication network of this chain.

Nodes c, d, and e are not illustrated in the configuration table, but the configuration table may comprise similar format and information.

When all nodes have the same response node order, each node can determine its position and route the next egress. Each node can find out from the network topology discovery phase that it is a downstream chain, and therefore each node can suggest a daisy chain mode.

Figure 8 shows another exemplary embodiment of a proposed network topology mode that can be configured for a ring configuration as shown in the present invention at the end of the discovery procedure. This exemplary embodiment is similar to that of Figure 7. The difference in this case is that each node has two adjacent nodes since there is no edge node. For this case, the nodes can send the probe back to the originator once they observe that their target adjacent node has already filled the information field of the discovery probe. In this particular case, each node can choose between two routes, clockwise and counterclockwise and advantageously the shortest path for the egress node as the default path and the other as the flexible path.

Table 801 in Figure 8 shows the configuration for node a, comprising nodes a, b, c, d, and response, egress set to no for nodes a, b, c, d, and set to yes for node and. Node a can configure the suggested suggested mode (8100) proposed in the ring and according to the suggested routing (8010), node a can forward data to node e and node e can be the egress node in the main communication network. Alternate routing field 8011 can provide the flexible path in the event of failure. For this case, alternative routing can forward data from node a to node b, then to node c, then to node d, and then to node e. Node e can be the egress node in the main communication network of this chain.

Table 802 in Figure 8 shows the configuration for node b, comprising nodes a, b, c, d, and response, egress set to no for nodes a, b, c, d, and set to yes for node and. Node b can configure the suggested suggested mode (8200) proposed in the ring, and according to the suggested routing (8020), node b can forward data to node a, and then to egress node e. Alternate routing field 8021 can provide the flexible path in the event of failure. For this case, alternate routing can forward data from node b to node c, then to node d, and then to node e. Node e can be the egress node to the main communication network of this chain.

Figure 9 shows an exemplary embodiment of a discovery probe that may be formatted for a completely disordered communication network as shown in the present invention during the network topology discovery initiation phase.

This is similar for figure 6, each node can send discovery probes but will also be the receiver of additional node discovery probes. If it is a receiving node, it can fill in the requested information and forward the probe to the other adjacent nodes but not back to the node that sent this probe. If the node has more than two adjacent nodes it can no longer forward the probe but instead send it back to the originator, assuming it is in a completely messy and configured mesh, it is the best suitable mode. If it has only one adjacent node, it will assume that it is an edge node. When it has two adjacent nodes it will send the discovery probes to both to derive its adjacent node status. After a while, each node will receive back the discovery probes of its eastern and western neighbors with all the requested data filled in.

In a further exemplary solution of the invention, the node can classify its adjacent nodes according to signal-to-noise ratio (S / I) into "class 1 neighbors" of class 1 and "class 2 neighbors" of nodes. class 2 adjacent nodes. If the node has more than two class 1 adjacent nodes, it can no longer forward the probe but instead send it

ES 2 396 014 T3 back to the originator, assuming it is in a completely messed up and configured mesh, is the best suitable mode. When you have two adjacent Class 1 nodes you can send probes to both to derive the adjacent node status. After a while, each node can receive back the probes from its eastern and western neighbors with all the requested data filled in.

The exemplary embodiment of a probe may have a format comprising the originator, address, "I am", egress, "class 1 neighbors" and "class 2 neighbors" information fields. The originator field can contain the identifier of the originating node, the address field can contain the address to which the discovery probe can be sent (east, west), the "I am" field can contain the node identifier that fills its information from adjacent node, the egress field can contain the information whether the node in question has access to a main communication network, the "class 1 neighbors" field can contain the identifiers of all adjacent nodes that have a connection that meets at least certain quality criteria and the "class 2 neighbors" field can contain the identifiers of all adjacent nodes that have a connectivity that does not meet certain quality criteria.

Table 901 of Figure 9 shows that node a can be the originator and does not need to send any discovery probe since there can be four adjacent nodes, node b, node c, node d, and node e.

Tables 902 and 903 in Figure 9 show that a node b can be the originator and can send a discovery probe since there can be two adjacent nodes, node a and node c.

The originating node b may add its adjacent node information 9000 to the discovery probe. The adjacent node information 9000 may comprise setting the "I am" field to ab, the egress field to no, the "class 1 neighbors" field to a and c, and the "class 2 neighbors" field to d. Thus, node b may have node a and node c as class 1 neighbors, may have no egress to the main communication network, and may have node d as adjacent "class 2 neighbors". Then node b can broadcast the discovery probes to its adjacent nodes, which go west to node a, and go east to node c.

The eastbound node c may add its adjacent node information 9020 to the discovery probe 902. The adjacent node information 9020 may comprise setting the "I am" field to c, the egress field to no, the "class 1 neighbors" field b and y, and the "class 2 neighbors" field d and e. Then node c can send the discovery probes to node a. Node a can configure the field "I am" aa, the field egress to no, the field "neighbors of class 1" ab, c, d, e and it is not necessary that any entry to the field "neighbors of class 2" as node a has an adjacent node of "class 2 neighbors". Then node a can send the discovery probes back to originating node b since node a can have more than two adjacent nodes as adjacent class 1 nodes.

The westbound node may add its adjacent node information 9030 to the discovery probe 903. The adjacent node information 9030 may comprise setting the "I am" field to aa, the egress field to no, the "class 1 neighbors" field ab, c, d, e and it is not necessary that any entry to the "class neighbors" field 2 "as node a has an adjacent node of" class 2 neighbors ". Then node a can send discovery probes back to originating node b since node c can have more than two adjacent class 1 nodes.

Figure 10 shows another exemplary embodiment of a proposed network topology mode that can be configured for a mesh configuration as shown in the present invention at the end of the network topology detection procedure.

The configuration table can be in a format comprising the information, originator, reply nodes, egress, suggested mode, and reason fields. The originator field can contain the identifier of the originating node, the response nodes field can contain the node identifiers of all nodes that respond with network topology discovery information, the egress field can contain the information of whether the node in question can have access to a main communication network, the suggested mode field may contain the proposed mode based on the network topology detection information and the reason field may contain the reason for the suggested mode decision.

Table 1001 of Figure 10 shows the configuration for node a, which comprises the response nodes a, and the egress set to no. Node a configures the suggested suggested mode (10100) in the mesh due to the reason, node a has too many class 1 neighbors.

Table 1002 of Figure 10 shows the configuration for node b, comprising nodes b, c, and response nodes, egress set to no for nodes b, c and a. Node a configures the suggested suggested mode (10200) in the mesh due to the reason, node a has too many class 1 neighbors.

Figure 11 shows another exemplary embodiment of a decision matrix that can be used for the resulting topology decision as shown in the present invention. This phase can happen after all or at least parts of the nodes that may have sent their proposals to additional nodes that filled their discovery probe. Therefore, all nodes or parts of them can have proposals for

ES 2 396 014 T3 network topology of parts of the nodes or all the nodes involved.

Before an autonomous switch to the appropriate network topology mode can occur, the resulting network topology decision alone can be made.

In this exemplary embodiment, there are three possible network topology modes to switch to, mesh mode, daisy chain mode, or ring mode. These modes can be classified as follows, high for ring mode, medium for daisy chain mode, and low for mesh mode.

Since each node can have the network topology proposals of parts or the rest of the involved nodes available, each node can perform a classification by itself without further communicating with others by applying the classification rule.

In table 1101 of Figure 11, all nodes, node a, b, c, d and e, propose the daisy chain network topology mode, so that the resulting mode (11100) is a daisy chain network topology and each node can switch to this resulting network topology mode.

In table 1102 of figure 11, nodes, node b, c, d, and e propose a daisy chain network topology mode (11202), but node a proposes a mesh network topology mode (11201), for what the resulting mode (11200) is a mesh network topology mode since the mesh has a lower ranking and each node in question can switch to this network topology mode.

In table 1103 of Figure 11, nodes, node b, c and d, propose a ring network topology mode, but nodes a and e propose a daisy chain network topology mode, so the mode (11300) The resulting daisy chain network topology mode can be calculated as the daisy chain can be ranked lower and each node in question can switch to this network topology mode.

Figure 12 shows an exemplary embodiment of the present invention, comprising a specific operation of a daisy chain configuration in which direct neighbor nodes can be skipped when data is forwarded. Aah nodes can be daisy-chained and traffic can be forwarded only along the chain.

Longitudinal lines connect the next adjacent nodes in the chain, skip those nodes, which can be directly adjacent to each other. As an example, node a skips node b when it forwards data to node c even though node b is a direct neighbor of node a. Since adjacent nodes can be classified in terms of quality, in the example of figure 12 node a can be connected to nodes c with a poorer signal-to-noise ratio (S / I) than to node b which is the neighbor direct. In a normal mode of operation, a frequency reuse of three is employed to avoid interference. Thus, in the 1200 sequence of Figure 12, node a uses a radio carrier c1 that forwards data to node c, node c can use a radio carrier c2 with respect to node e, and node e can use a radio carrier radio c3 with respect to node g before the radio carrier is used again in this chain. The skipped nodes can use the radio carrier through the radio carrier sequence to avoid interference. Thus, node b can use a radio carrier c3 with respect to node d, node d can use a radio carrier c1 with respect to node f, and node f can use a radio carrier c2 with respect to node h.

Figure 13 shows an exemplary embodiment of the present invention, in which the nodes discover the breakdown of a direct neighbor node. In this scenario, node d may fail in the operation. Direct neighbor nodes c and e can discover the breakdown and help forward data from affected nodes b and f.

Figure 14 shows an exemplary embodiment of the present invention, comprising a transparent flexibility mode and corresponding handling of a failover. When node d fails, one of the nodes, coe, can detect the broken link, for example by stopping receiving signals from d. In Figure 14, node c detects the failing link 1401 of node d. It informs node e of its suspicion by sending message M100 comprising the information of node d that has failed and an indication about its transparent handling capability and non-transparent flexibility modes. As an example, node c can have up to three radio headends handling up to three carriers in parallel. Upon receipt of this command message, node e can search for node d, it can detect detection 1402 of link failure of node d and can acknowledge its unavailability by sending message M200 comprising the information of the failed link of node d, and the suggestion that it uses a flexible transparent mode. Node c can confirm the suggested mode by sending the M300 message comprising the confirmation to use the transparent flexible mode. Then node c, as well as node e, can switch to a transparent flexibility mode and can establish transparent transmission 1403. The behavior of affected adjacent nodes b and f can be transparent with respect to node d as before when nodes c and e have adopted the role of d.

Figure 15 shows an exemplary embodiment of the present invention, comprising a non-transparent flexibility mode and corresponding handling of a failover. When node d fails, one of the nodes, coe, can detect the broken link, for example by stopping receiving signals from d. In FIG. 15, node c detects node d failure 1501. It informs node e of its suspicion by sending the M100 message that

ES 2 396 014 T3 comprises the information of the failed node d and an indication about its transparent handling capacity and non-transparent flexibility modes. As an example, node c can have up to three radio headends handling up to three carriers in parallel. Upon receipt of this command message, node e can search for node d, can detect link failure 1502 of node d and can acknowledge its unavailability by sending message M200 comprising the link failure information to node d, and the suggestion to use a flexible transparent mode. Node c can confirm the suggested mode by sending the M300 message comprising the confirmation to use the non-transparent flexible mode. Then node c can send an M400 message as well as node e can send an M500 message indicating that a non-transparent transmission can be established to its adjacent nodes, node b and node f, respectively. Node b and node f can switch to a non-transparent flexibility mode and can establish a non-transparent transmission 1503.

By using these flexibility methods, the system can operate in a beneficial way, with maximum overall throughput along the daisy chain because the point-to-point advantage can be used on dedicated carriers, flexibility guaranteed even if the nodes differ. In terms of radio resource capacities, the telecommunication network can operate with a single carrier as well as multi-carrier nodes.

This solution can be adapted in a beneficial way for existing WiFi solutions as conventional access points can run up to 3 carriers, identity management (SSID) can be carried out, one access point can be substituted for another by adopting the role of another without any additional control message flow, very economical especially when operating in an unlicensed band, and no synchronization (CSMA / CA) is necessary. The invented method can be applied to any existing air interface, licensed or unlicensed.