Network node for operation in case of unavailability of application control center

Abstract

The invention is directed to a network node (100) for communication in a wireless communication network (150), comprising an application unit (102) for performing one or more predetermined application functions. The network node comprises an input interface (104) for receiving an availability signal (AS) indicating availability or unavailability of a respective application control center for centralized control of data exchange (130) with respect to the respective application function. An operation control unit (106) is configured to switch operation of the application unit from a centralized operation mode to a distributed operation mode upon determining that the availability signal indicates unavailability of the respective application control center, thereby implementing an alternative operation mode in which instead of providing a first wireless communication signal (S1) to the application control center, a second communication signal (S2) is directly transmitted to one or more of the target network nodes (132).

Description

Technical Field

[0001] The present invention relates to a network node, a wireless communication network, a method for operating the network node and the wireless communication network, and a computer program. Background Technology

[0002] WO 2016 / 020472 A1 describes a control device including one or more transmitters configured to transmit control signals for controlling the operation of the controllable device via at least a first communication path between the control device and a controllable device. The first communication path includes a first network. The transmitters are also configured to transmit control signals for controlling the operation of the controllable device via at least a second communication path between the control device and the controllable device. The second communication path includes a second network. Determination logic determines whether an error exists in the first communication path. In response to the determination logic determining that an error exists in the first communication path, the control device switches from transmitting control signals via the first communication path to transmitting the control signals via the second communication path.

[0003] US 2010 / 100627 A1 discloses a system and method for bypassing an access point in a wireless local area network (LAN) to perform direct peer-to-peer data transmission. The system includes a user equipment equipped with a primary local wireless interface for establishing a wireless communication link with the access point of the wireless LAN, a secondary local wireless interface for direct peer-to-peer (P2P) file transfer, and a P2P file transfer application. When the P2P application requests to transfer a data file to another user equipment within the wireless LAN, the user equipment determines whether the other user equipment is within the coverage area of ​​the secondary local wireless interface and whether the file transfer satisfies one or more alternative transmission criteria. If so, the data file is transmitted to the other user equipment via the direct P2P wireless communication link, thereby bypassing the access point of the wireless LAN. Summary of the Invention

[0004] In some wireless communication networks, network nodes operate in a centralized manner to perform predetermined application functions, wherein the application control center acts as a control device for centrally controlling data exchange related to the application functions, and typically provides messages and / or instructions received from nodes in the wireless communication network to one or more nodes in the network that are intended to receive messages and / or instructions.

[0005] It would be beneficial to provide a network node that can operate within the same wireless communication network as other network nodes even when the application control center is unavailable.

[0006] According to a first aspect of the invention, a network node for communicating in a wireless communication network is described. The network node of the first aspect includes an application unit configured to perform one or more predetermined application functions and configured to generate and provide specific application wireless communication signals for reception within the wireless communication network. The network node also includes an input interface configured to receive a corresponding availability signal. The availability signal indicates the availability or unavailability of one or more application control centers used for centralized control of data exchange regarding the corresponding predetermined application function within the wireless communication network. The network node further includes an operation control unit connected to the input interface and configured to, upon determining that the availability signal indicates the unavailability of the corresponding application control center, switch the operation of the application unit from a centralized operation mode to a distributed operation mode regarding the corresponding predetermined application function.

[0007] The application unit of the network node in the first aspect of the present invention is configured to generate a first application-specific wireless communication signal in a centralized operation mode with respect to a corresponding predetermined application function, for communication via a corresponding application control center.

[0008] Furthermore, the application unit of the network node is configured to generate a second specific application communication signal for direct communication with at least one target network node in the wireless communication network in a distributed operation mode with respect to the corresponding predetermined application function, and to send them directly to one or more of the at least one target network node.

[0009] Therefore, network nodes belong to the wireless communication network and are configured to perform one or more application functions, each associated with a corresponding application control center. The application control center is a network node configured to centrally control data exchange related to the corresponding application function. In centralized operation mode, i.e., when the corresponding application control center is available, communication between the network node and other nodes in the wireless communication network is performed via the corresponding application control center, based on information provided by an availability signal. This application control center is configured to receive first application-specific wireless communication signals from the network node and, as expected or necessary, forward them to target network nodes according to predetermined algorithms or engine rules, or control one or more target network nodes.

[0010] Furthermore, the network nodes of the first aspect are advantageously configured to operate with respect to the corresponding application functions in another operating mode, referred to as the distributed operating mode. When the unavailability of the application control center is inferred from the corresponding availability signal, the application unit is switched to the distributed operating mode. In this distributed operating mode, the application unit is configured to generate and provide a second application-specific communication signal (which is not necessarily a wireless communication signal) for communicating with at least one target network node. The second application-specific wireless communication signal is directly transmitted to one or more of the at least one target network node. Thus, instead of attempting to communicate with the currently unavailable application control center, which does not result in the desired functionality and may lead to increased network traffic, the application unit of the network node is switched to the distributed operating mode, which bridges the application control center and allows the given functionality even when the application control center is unavailable.

[0011] The embodiments of the first aspect of the present invention will now be described.

[0012] In one embodiment, a network node includes an application unit configured to cooperate and communicate with the remaining network nodes of the wireless communication network to perform an application function, such as a lighting function, an HVAC function, a presence sensing function, a security monitoring function, or any other suitable application function. In this embodiment, the application control center that controls data exchange within the wireless communication network is referred to as a network control node. In another embodiment, the application unit is configured to perform multiple application functions, such as any combination of the above functions, and requires a corresponding application control center to centrally control data exchange associated with different application functions. In one embodiment, the application control center is configured to control data exchange associated with more than one application function. When an availability signal indicates the presence of one or more available application control centers in a first group and one or more unavailable application control centers in a second group, the network node is advantageously configured to operate the application unit simultaneously in a centralized operating mode with respect to one or more application functions controlled by the first group of application control centers, and in a distributed operating mode with respect to one or more other application functions controlled by the second group of application control centers.

[0013] In various embodiments, the application control center is a router, access point, bridge, gateway, perimeter gateway, or any other suitable network node adapted to control data exchange related to a given application function between network nodes or between a network node and the application control center. In one embodiment, the application control center is configured to further control the exchange or provision of actuation signals or operation instructions for controlling the operation of one or more network nodes in the wireless communication network, based on a received first application-specific wireless communication signal. An exemplary application control center is configured to transmit a start signal or operation instruction provided by the first application-specific wireless communication signal. Additionally or alternatively, another exemplary application control center is configured to generate and provide a start signal or operation instruction based on the received first application-specific wireless communication signal according to a predetermined algorithm. For example, a first application-specific wireless communication signal indicating that an on button has been pressed results in the generation and provision of an operation instruction that directs the activation of a given functional unit of the network node, such as a lighting unit, a ventilation unit, or other known alternative unit.

[0014] In a particular embodiment, more than one application control center is configured to centrally control data exchange regarding a given application function, and may also include actuation signals or operating commands. In this embodiment, a distributed operating mode is switched when an availability signal indicates that those application control centers are unavailable in controlling data exchange regarding a given application function.

[0015] In another embodiment, each application control center that controls data exchange regarding the same application function is associated with a corresponding subset of network nodes. If one of the application control centers is currently unavailable, as indicated by an availability signal, the network nodes of the subset associated with the unavailable application control center are configured to communicate with one of the remaining application control centers that are still available for that application function.

[0016] For example, in a relatively long-range wireless communication network, two or more application control centers (ACCs) are configured to control application functions, including collecting information from network nodes. Each ACC is positioned to serve a subset of network nodes, specifically those closest to the ACC. Network traffic from each subset of network nodes is primarily retained within one part of the wireless communication network, while network traffic from another subset is retained in another part. Compared to a single ACC, messages from two subsets of network nodes can be sent simultaneously, increasing overall network capacity. If one ACC becomes unavailable, the remaining ACCs can still serve the entire wireless communication network, albeit at a lower rate.

[0017] Similarly, in another example, two or more application control centers are associated with the software update functionality of network nodes in wireless communication. Each application control center serves a subset of network nodes, typically depending on their installation location, and two or more application control centers can be used simultaneously to perform software update functions concurrently. If one or more application control centers become unavailable again, the available application control centers can still serve the network nodes initially served by the unavailable application control centers, although overall performance may be lower in some cases.

[0018] In these embodiments, the unavailability of the application control center does not lead to a switch from a centralized operating mode to a distributed operating mode, because at least one other available application control center controls the data exchange regarding the same application functions as the unavailable application control center.

[0019] In a preferred embodiment, the distributed operation mode is advantageously configured to perform a so-called moderately degraded operation mode with respect to the corresponding application functions. Switching to the moderately degraded operation mode occurs when a given availability signal indicates that the corresponding application control center, configured to handle communication between network nodes of the wireless communication network, is unavailable for any given reason. This ensures that even without the application control center, certain functions that are typically limited or reduced compared to the application functions enabled during operation in centralized operation mode remain available. In this sense, the application control center is considered unavailable when it is disconnected from the wireless communication network or otherwise unable to communicate with other devices or nodes on the wireless communication network, either currently or expected to be unable to do so.

[0020] In one embodiment, the operation control unit is further configured to switch the operation of the application unit from distributed operation mode to centralized operation mode when an availability signal indicates the availability of the corresponding application control center, while the application unit is operating in distributed operation mode for a predetermined application function. In this preferred embodiment, the operation mode for the corresponding predetermined application function of the application unit can be switched from centralized operation mode to distributed operation mode, and vice versa; that is, the switch from distributed operation mode to centralized operation mode depends on the corresponding availability signal.

[0021] In another embodiment, which may also include any of the features described above, the network node further includes an application control center detection unit configured to determine the availability or unavailability of one or more application control centers within the wireless communication network and provide a corresponding availability signal to an input interface. In a particular embodiment, the application control center detection unit is advantageously configured to monitor wireless communication signals directed to a target network node in a centralized operating mode and assume that the application control center is no longer available when it is determined that the application control center is not providing the expected wireless communication signal to the target network node. For example, and as a non-limiting example, the network node is a device such as a switch or sensor for controlling the operation of a target network node such as a wirelessly controllable illuminator. In this exemplary case, the application function is a lighting control function, wherein the application control center controls data exchange between network nodes when available. In this example, the network node in centralized operating mode generates a first application-specific wireless communication signal and sends it to the application control center, which then provides a wireless operating signal including instructions for controlling the illuminator based on the received first application-specific wireless communication signal. The application control center detection unit in this particular embodiment is configured to detect whether a wireless operation signal has been transmitted, and, if the wireless operation signal is not transmitted within a predetermined time span, to provide an availability signal indicating that the application control center is unavailable. Receiving the availability signal indicating that the application control center is unavailable causes a change in the operating mode of the network node, which is switched to a distributed operating mode for lighting control functions. When operating in this distributed operating mode, the network node is advantageously configured to generate second application-specific communication signals and provide them directly to one or more of at least one target network node. The payload content of the first and second communication signals does not necessarily have to be the same. In the first case, it includes, for example, status information about the current state of a switch or sensor, which is then converted by the application control center into instructions for controlling the target network node, for example, according to a predetermined algorithm or engine rule. In the second case, it includes, for example, instructions for directly controlling the target network node. Alternatively, the second communication signal includes status information, and the target network node is appropriately configured to interpret the received status information and control its operation based on it. Alternatively or additionally, in a particular embodiment, the application control center is configured to detect an presence notification signal provided by the application control center indicating the availability of the previously unavailable application control center, and to provide a corresponding availability signal based on the receipt of the presence notification signal. This causes the operation control unit to switch from a distributed operation mode to a centralized operation mode. In another embodiment, the network node having the application control center detection unit is also configured to provide the corresponding availability signal to the input interface of other network nodes in the wireless communication network.

[0022] In one embodiment, the application control center detection unit includes a network monitoring unit configured to monitor wireless communication signals within a wireless communication network and use the monitored wireless communication signals to determine the availability or unavailability of the application control center.

[0023] For example, in one embodiment, to determine the unavailability of the application control center, the network monitoring unit is configured to detect certain anomalies in network traffic associated with the missing application control center. A non-limiting list of such anomalies includes:

[0024] (i) Detecting lost routine messages from the application control center, even if these messages are not directed to network nodes, can be monitored in so-called “promiscuous mode.” In a particular embodiment, these routine messages include optical state polling in the Hue system, and / or MTO routing requests from bridges acting as the application control center in the Hue system, and / or acknowledgments or responses from the application control center (e.g., at the MAC, ZDO, APS, or ZCL levels), and / or dedicated keep-alive messages from the application control center, or any combination thereof;

[0025] (ii) The number of routing requests or other discovery messages detected by the application control center exceeds a predetermined threshold. For example, in a wireless communication network using Zigbee as the wireless communication protocol, discovery messages include IEEE_addr_req / NWK_addr_req. Even on a stable wireless communication network, some of these messages may occur, for example, due to changes in propagation conditions or interference, resulting in the loss of multiple link states. Therefore, the predetermined threshold should be appropriately selected, taking into account the number of such messages exchanged by the application control center when it is available and network nodes are operating in centralized operation mode for a given application function.

[0026] (iii) A so-called “last breath” message from the application control center was detected, which indicated the expected unavailability of the application control center;

[0027] (iv) Detection of lost link state messages from the application control center by network nodes within one hop of the application control center. Network nodes within one hop of the application control center are appropriately configured to detect the disappearance of the application control center from link state messages from other nodes in the wireless communication network. Alternatively or additionally, nodes within the application control center's range are appropriately configured to notify network nodes that the application control center is unavailable.

[0028] (v) Out-of-band detection of certain events by other nodes in this or other wireless communication networks. For example, a node in a non-lighting system, such as a security camera, detects the presence of an object and also detects that lights associated with the detected area are not turned on as expected. The security camera is configured to ping network nodes, for example via BLE or other alternative wireless communication protocols, to compare notes / inquire about the cause of the unexpected behavior. This ping is used as an availability signal indicating the unavailability of the application control center; and

[0029] (vi) Detect other lost signals sent by the application control center, such as Wi-Fi, for example in the case of a permanent bridge / hub type application control center, or Bluetooth signals, in the case of a smartphone temporary application control center;

[0030] (vii) The number of identical or related first application-specific wireless communication signals detected within a given time span, exceeding a predetermined threshold amount. For example, in a lighting arrangement, a user activates a button to turn a given light fixture on or off. If the application control center is unavailable, the light fixture may not respond as the user wishes, and he or she may activate the button again, resulting in the generation and provision of identical or related first application-specific wireless communication signals within a relatively short time span. The detection of these identical (e.g., instructions to turn the light fixture on or off) or related (e.g., instructions to turn the light fixture on and off consecutively) first wireless communication signals is used as an availability signal.

[0031] In certain embodiments, the network monitoring unit is further configured to provide an availability signal based on the current duration of the determined unavailability of the application control center. For example, in a particular embodiment, if the application control center is unavailable for a duration less than a first time span (e.g., 60 seconds, equivalent to the loss of 3 consecutive link status messages) or other first time span durations, no corrective action may be required, and the application unit can remain in centralized operation mode without switching to distributed operation mode for the corresponding application function. However, if the application control center is unavailable for a second time span (e.g., 1-60 minutes) starting after the end of the first time span, an availability signal indicating the application control center system unavailability is provided to the input interface, and the network node operates in distributed operation mode for the application function. Alternatively, if the application control center is continuously unavailable for a predetermined time span equal to the sum of the first and second time spans, the nodes of the wireless communication network are instructed to adopt a predetermined state. For example, in the case of a lighting arrangement, lighting nodes are instructed to turn on to maximize user safety. The durations of the first and second time spans and the behavior of each of these modes are programmable and therefore adaptable to a given wireless communication network. For example, if the complete software update cycle or restart cycle of the application control center takes a certain amount of time, the duration of the first time span is advantageously set to be suitable for that certain amount of time.

[0032] In one embodiment, the application control center detection unit is further configured to determine the expected disconnection time span of the application control center from the wireless communication network and provide a disconnection time signal indicating this. Furthermore, the operation control unit is configured to receive the disconnection time signal and, further, when determining that the expected disconnection time span is longer than a predetermined threshold time span, switch the operation of the application unit regarding the corresponding application function from a centralized operation mode to a distributed operation mode.

[0033] In another embodiment—which may also include any of the features described above with reference to any prior embodiment according to the first aspect—the network node further includes a storage unit for storing routing data indicating available communication routes within the wireless communication network, the routing data including one or more control node entries relating to communication routes between the network node and the application control center. In this particular embodiment, a transmitter unit is connected to the storage unit and configured to provide a first wireless communication signal based on the routing data, and an operation control unit is configured to disable the transmitter unit's access to control node entries for a predetermined time span in a distributed operation mode. The selection of the duration of the predetermined time span allows for temporary or complete disabling of access to control node entries. However, in one embodiment, control node entries entered at a later time point may be accessible, so complete disabling is equivalent to removing the control node entry from the routing data. In one embodiment, the routing data includes one or more of the following: bindings, routing table entries, neighbor table entries, address mapping entries, etc., or any combination thereof.

[0034] In another embodiment, this embodiment may also include any features described above with reference to any prior embodiment according to the first aspect, wherein the network node further includes a storage unit for storing network data. The network data indicates the network node of the wireless communication network and includes one or more application control center entries associated with the corresponding application control. In this particular embodiment, the application unit is connected to the storage unit and configured to provide a first specific application wireless communication signal based on the network data. The operation control unit is configured to disable the application unit's access to the control node entries for a predetermined time span when the application unit operates in a distributed operation mode with respect to the corresponding application function.

[0035] In a particular embodiment, the storage unit is configured to store network data in the form of routing data indicating available communication routes between network nodes within the wireless communication network. The routing data includes one or more application control center entries relating to communication routes between network nodes and application control centers. An application unit is connected to the storage unit and configured to provide a first application-specific wireless communication signal based on the routing data. An operation control unit is configured to disable the application unit's access to control node entries for a predetermined time span when the application unit is operating in a distributed operation mode with respect to a corresponding application function.

[0036] The choice of the duration of the predetermined time span allows for temporary or complete disabling of access to application control center entries. However, in one embodiment, application control center entries entered and stored at a later time point can be accessed, so complete disabling is equivalent to removing existing previous application control center entries from the network data or routing data. In one embodiment, the network data or routing data includes one or more of the following: bindings, routing table entries, neighbor table entries, address mapping entries, etc., or any combination thereof.

[0037] Removing application control center entries is particularly advantageous when the application control center is configured to perform network initialization or update of nodes. This initialization or update does not involve routine operation of the wireless communication network but primarily involves performing the initial setup process of the wireless communication network or updating the existing firmware or software of network nodes. Therefore, removing application control center entries from network or routing data allows the release of resources occupied by those entries. On the other hand, temporarily disabling access to application control center entries is especially advantageous when the application control center is expected to be temporarily unavailable (e.g., during maintenance). Furthermore, this is advantageous when the application control center is intermittently available and unavailable, but when available, immediate control of the wireless communication network is required. A non-limiting example is a user's smartphone serving as the application control center, which includes a lighting control app for controlling lighting nodes in a home setup. Similarly, as another example, a forklift in a warehouse features an application control center for lighting control functions, controlling one or more independent lighting networks for each isle. For example, forklifts are configured to fuse sensor data from their onboard sensors to determine lighting settings for the lights, thereby alerting workers to the approaching forklift and its intentions.

[0038] Furthermore, in one embodiment, based on an availability signal, access to an application control center entry is temporarily disabled until it becomes available again by blocking, clearing, or queuing outgoing traffic to the application control center address. Since traffic to the application control center may be generated by multiple layers (ZCL, e.g., reporting light status; ZDO, e.g., performing rediscovery; APS, e.g., requesting key updates; and NWK, e.g., starting route discovery), care must be taken to ensure that all of the aforementioned traffic is blocked without side effects (e.g., lost ACK or response messages), leading to a discovery storm. Alternatively or additionally, embodiments also include a storage unit for storing the “temporarily disabled” state of different entries, such that communication at the layer managing the table is immediately discarded, e.g., the APS of the binding table, and the NWK of the neighbor and routing tables. A particular application control center is advantageously configured to communicate its availability / unavailability to trigger a reset or setting of this state. Alternatively, the application control center is configured to carry this on its regular messages, if any, such as in the form of a type-length-value parameter appended to a command. For example, MTORR (Many-to-One Routing Request) – which might be sent periodically by the application control center – is used to transmit a Type Length Value (TLV) and instructions to enable / disable entries. Alternatively, the TLV is added to a periodically broadcast "keep-alive" message. This particular alternative requires the application control center to send a message disabling entries shortly before disappearing from the network.

[0039] Similarly, specific application control centers are configured to provide availability signals to indicate that they are "back" or "will return" to the wireless communication network. For example, after a reboot, an application control center first indicates to at least one network node in the wireless communication network that it is currently rejoining the network. Additionally, the application control center can query one or more network nodes for information about how urgently it needs to rejoin the network. In some exemplary application control centers, the indication to return to the communication network is sent at its own discretion, for example, as part of a software update bootstrapping, only for temporary returns. Examples of such indications are "Device Announcements," MTORR, or dedicated commands available in Zigbee. The indication returned by the application control center can provide further explicit instructions to network nodes. For example, regarding the application function involving a given application control center, its reception may be used as an instruction to switch to centralized operation control mode. Enabling this as a dedicated option—which is independent of communication with the application control center—allows the application control center, which is temporarily used as a diagnostic and maintenance tool, to observe (and adjust as necessary) the distributed operating patterns of network nodes; for example, an iRobot forklift / vacuum cleaner can be used as a perimeter gateway to perform computationally intensive, high-quality RF sensing in specific areas of a building, in conjunction with Wi-Fi lights, after Wi-Fi light-based RF sensing has already flagged potential events such as leaks in the home or warehouse.

[0040] Additionally, in another embodiment of the network node, receiving an indication that the application control center is rejoining the wireless communication network is used as an instruction for the network node to resume reporting to the application control center from a period when the application control center is unavailable. This may include any queued messages, such as in aggregated or summarized form. Additionally or alternatively, receiving an indication that the application control center is rejoining the wireless communication network is also used to trigger the removal of settings associated with the distributed operation mode, including, for example, bindings and group memberships.

[0041] In another embodiment—which may include any of the technical features described with respect to any of the foregoing embodiments—the network node further includes a receiver unit for receiving wireless communication signals from an application control center of the wireless communication network, and a functional unit connected to the receiver unit and configured to perform wirelessly controllable node functions. Preferably, the receiver unit, together with a transmitter unit for transmitting wireless communication signals, forms a transceiver unit for providing and receiving wireless communication signals to communicate with other network nodes (including one or more application control centers) of the wireless communication network. In this embodiment, a first specific application wireless communication signal and a second communication signal, both generated by the application unit, include corresponding control data for controlling the functional unit. In a centralized operation mode, the first wireless communication signal is provided to the application control center, which then sends specific instructions back to the receiver unit for controlling node functions. A non-limiting example of such a network node is given by a illuminator having an integrated presence sensor and forming part of a lighting network using the IEEE 802.11 or IEEE 802.15, preferably IEEE 802.15.4 wireless communication protocol. In this particular example, the functional unit is a lighting unit for lighting. The application unit provides the application control center with an indication, determined by an integrated presence sensor, that a person has entered the room, as a first application-specific wireless communication signal. The application control center, knowing the lighting is currently off, sends an on command to the lighting according to a predetermined algorithm or rule engine, which turns on the functional unit (i.e., the lighting unit). Therefore, the on command provided by the application control center in response to the reception of the first application-specific wireless communication signal is used to control the node function of the network node, i.e., the functional unit controlling the network node. However, if the application control center is unavailable, operation in centralized mode will not result in the lighting being turned on when a person is detected. In this case, the person is still detected, and the first application-specific wireless communication signal is sent to the application control center. However, due to unavailability, the application control center cannot send back the necessary signals to control the node function. Therefore, the operation control node in this embodiment is configured to switch the operation of the application unit to a distributed operation mode. In this mode, the application unit is configured to directly provide a second communication signal to the functional unit for performing the node function. In the example of a illuminator with an integrated presence sensor, or any similar example, the second application-specific communication signal is not a wireless signal, but is provided via an electrical connection, and turns the illuminator on.

[0042] In another embodiment, when the application unit operates in a distributed operation mode, a second application-specific communication signal is directly transmitted to one or more target network nodes as a radio broadcast or radio multicast signal with a predetermined maximum allowed hop count. Preferably, the second application-specific communication signal is directly transmitted to one or more target network nodes as a single-hop transmission as a radio broadcast or radio multicast signal. This is particularly advantageous for network nodes controlled by other network nodes operating in their direct vicinity, such as lighting fixtures that can be controlled by switches or sensors located in the same room.

[0043] In another embodiment, when the application unit operates in a distributed operation mode, a second application-specific communication signal is sent directly to one or more target network nodes as a corresponding unicast message.

[0044] In another embodiment—which may also include any of the technical features described with respect to the previous embodiments—the network node further includes a user input interface for receiving user input signals. The user input interface includes, but is not limited to, buttons, switches, sliding or rotating controllers, touchpads, presence sensors, voice control, motion sensors, etc.

[0045] In this embodiment, the application unit is connected to the user input interface and configured to generate and provide a first application-specific wireless communication signal and a second application-specific wireless communication signal based on received user input signals. Therefore, in a centralized operation mode concerning a given application function, the application unit is configured to provide the first application-specific wireless communication signal to the application control center, indicating the current state of the user input interface, such as the position of a button, switch, or controller, or a state sensed by a sensor. Furthermore, in a distributed operation mode, the second application-specific wireless or wired communication signal is provided directly to a target network node, which, as explained above, is in some embodiments the same network node providing the first and second application-specific communication signals. The second communication signal preferably indicates instructions for controlling the operation of the target network node, depending on the current state of the user input interface. Alternatively, the second communication signal includes information related to the current state of the user input interface, which is then interpreted by the target network node, for example, to control its functional units to perform corresponding node functions.

[0046] The following sections provide some non-restricted examples of operation in distributed operation mode. Distributed operation mode is triggered when an availability signal indicates that the application control center is unavailable. The following non-restricted examples are given for a button-type user input interface used to control a lighting system; however, these examples can be generalized to other user input interfaces and other target network nodes as described above.

[0047] a) When the user presses "On" or its presence is detected, an "On" event is sent to the entire network, for example as a Zigbee broadcast message addressing all network nodes in the wireless communication network. This may result in too many lights being turned on, but at least the user is not in darkness. A preferred alternative is to send a similar broadcast message, but with a limited number of hops, meaning it will not be replayed throughout the network; the number of hops could be, for example, one or two hops. This limits the light effect to the area around the switch or sensor.

[0048] b) When the user presses "off" a predetermined number of times (once in a particular embodiment), an "off" event is sent to the entire network, preferably with a predetermined transition time to allow the user to leave the area before the light is actually turned off.

[0049] c) For better localized control, the application control center is configured to set up Zigbee groups that the user has already configured in the app for programmed behavior within the application control center to switches or sensors. Then, on / off / dimming / scene commands are sent directly from the switch to the lights in that group, for example, as multicast to that specific Zigbee group. Preferably, this only occurs in distributed operation modes as a "moderate degradation" mode, because their centralized operation modes can be richer than what switches or sensors can do in distributed operation modes, such as dynamic scenes, scenes depending on the time of day, different groups of different switches or sensors, etc. In this case, the network node with the switch or sensor needs some time to realize that the application control center or gateway has disappeared, and therefore there is an "idle" time during which the user's reaction does not result in any lighting effect. To solve this problem, one embodiment of the network node is configured to monitor light commands for the light groups it should control, according to the bridge's programming. If such a command is expected but not present, it can send a "moderate degradation" light control message. In one embodiment, this is implemented as a self-learning algorithm to detect anomalies in the traffic flowing through the system. Preferably, multiple network nodes perform distributed anomaly detection, with several end nodes locally sharing their observations. If one end node determines that the application control center is fully operational again, the end nodes also notify each other; this increases system recovery after the application control center becomes unavailable. Alternatively or additionally, if one end node determines that the application control center is currently unavailable, the end nodes notify each other. The fact that network nodes need to monitor optical control messages can limit the application control center's freedom to program its algorithm or rule engine. In one example, the only commands that network nodes can detect are multicast / broadcast commands; that is, unicast commands to nodes in the wireless communication network cannot be monitored by switching. Furthermore, if the application control center chooses not to react to certain triggers, network nodes may still potentially trigger certain behaviors due to any rules. To mitigate this risk, a suitable application control center has the ability to explicitly program the devices (and their endpoints / clusters) for which this behavior is enabled. Furthermore, the enabling of this behavior can be conditional upon a user repeatedly clicking the same button or multiple user actions indicating failure / dissatisfaction. One possible solution to the "unicast" problem is that network nodes with user input interfaces listen for those messages using a so-called promiscuous sniffing mode. Alternatively, in cases where there is only unicast or no response at all, the application control center is configured to send some pseudo-multicast messages so that network nodes still know that the application control center has received the command.

[0050] d) Regardless of the availability of the application control center (e.g., a bridge), network nodes are configured to send some optical control commands, and then the application control center itself (if available) sends another command for fine-tuning. This approach is advantageous in situations where the wireless communication network experiences temporary large latency due to wireless interference, or where the application control center is very slow but still available, or where communication to / from the application control center is delayed but not lost. Nodes in the wireless communication network are advantageously configured to use anomaly detection mechanisms to determine whether to send local lighting commands.

[0051] The programming of the network node and the set of behavioral rules in the application control center described in step "c" above are preferably defined in a compatible manner. This provides the best experience because there is always a light control that responds to the user's touch, and the user will have the best experience if the application control center is available. For example, a network node sends a command instructing that the lights of its associated lighting device be turned on to a brightness value of 50%, "bri=50%", and a color temperature of 2700K, "ct=2700K". The application control center improves this by subsequently sending bri=75%, ct= (a dynamic value based on the time of day).

[0052] Furthermore, when the unavailability of the application control center is detected, embodiments of the network nodes are configured to limit the complexity of the functions available to the user. For example, a switch could avoid sending color control or circadian rhythm commands, instead sending on / off and dimming commands. In another extension, instead of sending relative commands ("increase brightness by 10", "toggle"), network nodes are configured to send absolute commands ("on", "go to level 128") to ensure that the light effects on all target network nodes in a group controlled by network nodes including switches or sensors are synchronized.

[0053] According to a second aspect of the invention, a wireless communication network is provided. The wireless communication network includes at least one network node according to the first aspect of the invention, and at least one application control center for centralized control of data exchange related to a corresponding application function. The corresponding application control center is configured to receive a first application-specific wireless communication signal from the network node as an input wireless communication signal, the input wireless communication signal including a payload indicating control instructions for controlling the operation of one or more target network nodes. The application control center is also configured to provide an output wireless communication signal including control instructions to the one or more target network nodes.

[0054] Therefore, wireless communication networks share the advantages of network nodes in the first aspect of the present invention.

[0055] Different embodiments of wireless communication networks include different embodiments of network nodes.

[0056] In different embodiments, the application control center is a router, access point, bridge, gateway, perimeter gateway, or any other suitable network node for controlling data exchange between network nodes or between network nodes and the application control center in relation to a given application function.

[0057] In an embodiment of the wireless communication network in the second aspect, the application control center is configured to provide an availability signal to the input interface of at least one network node, the availability signal indicating the expected unavailability of the application control center within the wireless communication network. In this embodiment, the operation control unit of at least one network node is configured to, upon receiving the availability signal indicating the expected unavailability of the application control center, switch the operation of the network node's application unit from a centralized operation mode to a distributed operation mode with respect to a corresponding predetermined application function.

[0058] In another embodiment, at least one network node includes an operation control unit further configured to, in a distributed operation mode, switch the network node's operation from a distributed operation mode to a centralized operation mode upon determining an availability signal indicating the availability of an application control center, and when the application control center is temporarily disconnected from the wireless communication network, the application control center is configured to provide the at least one network node with an availability signal indicating the expected availability of the application control center within the wireless communication network. In this embodiment, the operation control unit is configured to switch the network node's operation from a distributed operation mode to a centralized operation mode upon receiving an availability signal indicating the expected availability of the application control center.

[0059] Advantageously, the application control center can indicate to network nodes its disappearance or unavailability, including whether it is temporary or permanent, or the application control center's speed / direction of movement in space. A specific application control center includes means for sending this indication, depending on the type and duration of the expected absence. The indication may also include detailed instructions to network nodes in the form of parameters or flags regarding how to proceed.

[0060] One embodiment of the application control center is preferably configured such that, when operating in a distributed operation mode, the instruction network nodes perform any of the actions listed below:

[0061] - Temporarily suspend any reporting to the application control center; this is especially useful in cases where the application control center is temporarily absent (e.g., for SW updates, a few seconds or minutes), as it will prevent network nodes reporting to the application control center from detecting the disconnected connection, thus triggering numerous unnecessary routing requests and consequently destabilizing the entire wireless communication network; and / or

[0062] - Remove any references that network nodes have on the application control center, such as bindings, routing table entries, neighbor table entries, address mapping entries, etc. This is especially useful when the application control center only performs the role of network entry initialization tools and does not participate in the day-to-day operation of the communication network; it allows the release of resources occupied by entries related to the application control center; or

[0063] - Temporarily disable any references to the device in the application control center, such as bindings, routing table entries, neighbor table entries, address mapping entries, etc.

[0064] According to a third aspect of the present invention, a method for operating a network node communicating in a wireless communication network is described, the method comprising:

[0065] - Generates and provides application-specific wireless communication signals for reception within a wireless communication network;

[0066] - Receive a corresponding availability signal indicating the availability or unavailability of one or more application control centers, which are used for centralized control of data exchange regarding corresponding predetermined application functions within a wireless communication network;

[0067] - When an availability signal indicates that the corresponding application control center is unavailable, the operation of the application unit on the network node is switched from centralized operation mode to distributed operation mode for the corresponding pre-defined application function; whereby...

[0068] - Regarding the operation of the corresponding pre-defined application functions in centralized operation mode, this includes generating a first application-specific wireless communication signal for communication via the corresponding application control center; and

[0069] - Regarding the corresponding pre-defined application functions operating in distributed operation mode, this includes generating second specific application communication signals for direct communication with at least one target network node, and sending them directly to one or more of the at least one target network node.

[0070] Therefore, the method of the third aspect shares the advantages of the network nodes of the first aspect of the present invention.

[0071] A fourth aspect of the invention is formed by a method for operating a wireless communication network. The method includes:

[0072] - The method for performing the third aspect of the invention; and

[0073] - When the corresponding predetermined application function is operated in centralized operation mode, a first application-specific wireless communication signal is received from the network node as an input wireless communication signal, the input wireless communication signal including a payload of control instructions for controlling the operation of one or more target network nodes, and an output wireless communication signal including the control instructions is provided to one or more target network nodes.

[0074] Therefore, the method of the fourth aspect shares the advantages of the wireless communication network of the second aspect of the present invention.

[0075] The fifth aspect of the invention is formed by a computer program including instructions that, when executed by a computer, cause the computer to perform the method of the third or fourth aspect of the invention.

[0076] It should be understood that the network nodes, wireless communication networks, methods, and computer programs described in this invention have similar and / or identical preferred embodiments, particularly those described in the embodiments above.

[0077] It should be understood that the preferred embodiments of the present invention may also be any combination of the dependent claims or the above embodiments and their respective independent claims.

[0078] These and other aspects of the invention will become clear and explained with reference to the embodiments described below. Attached Figure Description

[0079] In the following figures:

[0080] Figure 1 A schematic diagram illustrating an embodiment of a wireless communication network including network nodes and an application control center is shown.

[0081] Figure 2 A schematic block diagram of one embodiment of a network node is shown.

[0082] Figure 3 A schematic block diagram of another embodiment of a network node is shown.

[0083] Figure 4 A schematic block diagram of yet another embodiment of a network node is shown.

[0084] Figure 5 A flowchart illustrating an embodiment of a method for operating a network node is shown, and

[0085] Figure 6 A flowchart illustrating an embodiment of a method for operating a wireless communication network is shown. Detailed Implementation

[0086] Figure 1A schematic diagram of an embodiment of a wireless communication network 150 including network node 100, application control center 130, and target network node 132 is shown. Network node 100 is adapted to communicate within the wireless communication network 150 and includes an application unit 102 configured to perform one or more predetermined application functions and generate and provide respective application-specific wireless communication signals S1, S2 for reception by neighboring nodes 130, 132 within the wireless communication network 150. Network node 100 includes an input interface 104 configured to receive a corresponding availability signal AS indicating the availability or unavailability of the application control center 130 within the wireless communication network 150. The application control center is a network node used for centralized control of data exchange associated with a given one or a set of application functions. In the exemplary wireless communication network 150, the availability signal is provided to network node 100, for example, by a dedicated node of the network. Alternatively or additionally, reference will be made to the following... Figure 2 and Figure 3 The other network nodes discussed are configured to determine the availability or unavailability of the network control node, and / or receive availability signals directly from the application control center.

[0087] The control node 100 also includes an operation control unit 106, which is connected to the input interface 104 and configured to switch the operation of the application unit 102 from a centralized operation mode to a distributed operation mode for the corresponding predetermined application function when an availability signal indicates that the corresponding application control center 130 is unavailable.

[0088] In a centralized operation mode concerning the corresponding application function, the application unit is configured to generate a first application-specific wireless communication signal S1 for communication within the wireless communication network 150 via the application control center 130. Therefore, the first application-specific wireless communication signal is preferably a unicast message sent to the application control center, which typically operates using predetermined algorithms or engine rules, and whenever necessary, transmits an output message S3 to the target network node 132 based on the received first application-specific wireless communication signal. As an example, in an environment of a lighting network used to perform lighting control functions as application functions, the network node 100 is configured to control the operation of wirelessly controllable lighting devices (e.g., the target network node 132). For example, the first application-specific wireless communication signal indicates the current state of a switch used to control the lighting device 132. When a user activates the switch to turn on the lighting device, the network node sends the first application-specific wireless communication signal S1 indicating that the switch has been activated. Based on the algorithm or engine rules that associate the switch with the lighting device 132, the application control center sends an output message S3 indicating an instruction to turn on the light according to the activation of the switch.

[0089] However, the application unit 102 of network node 100 is also operable in a distributed operation mode. In the distributed operation mode, the application unit 102 is configured to generate second application-specific communication signals S2 for communicating with at least one target network node 132, and send them directly to one or more of the target network nodes.

[0090] In the example of the lighting network, when it is determined that the application control center is currently unavailable, the application unit operates in a distributed operation mode. In this mode, when a user activates a switch, the network node is configured to directly provide a second application-specific communication signal S2 to the target node 132. In this particular example, the second application-specific communication signal S2 is also a wireless signal. The second communication signal includes information about the switch state, which is then interpreted by the target network node to internally generate instructions for operating the target network node 132 based on the switch state, or it directly includes instructions for operating the target network node 132.

[0091] Another exemplary wireless communication network (not shown) includes more than one application control center, each configured to control data exchange or a corresponding application function or set of application functions. For example, in addition to application control center 130 configured to control data exchange related to the aforementioned lighting control function, other application control centers are part of the network and configured to control data exchange related to other application functions. For example, the wireless communication network may include a peripheral gateway for cooperating with other network nodes to perform a people counting function as an application function different from the lighting control function. Additionally or alternatively, the wireless communication network may include dedicated application control centers for controlling data exchange related to HVAC functions of a heating, ventilation, and air conditioning (HVAC) system in or within a building, security monitoring functions, and audiovisual control functions for controlling, for example, beams or sound or video systems. In cases where the wireless communication network includes multiple application control centers, each application control center is associated with a different function, and the operation of the application unit in a centralized or distributed operating mode is defined with respect to the corresponding application function. For example, an application unit of a network node operates in a distributed operating mode regarding the lighting control function because the corresponding application control center (e.g., a Hue bridge) is currently unavailable. Furthermore, the same network nodes operate in a centralized mode for HVAC functions and provide the generated first HVAC-specific wireless communication signal to the corresponding HVAC control center.

[0092] Another exemplary wireless communication network includes a lighting gateway acting as an application control center for controlling lighting functions and an HVAC controller for controlling HVAC functions. At least some of the lighting fixtures, serving as network nodes in the wireless communication network, include both occupancy sensors and sensor bundles with temperature and humidity sensors. The lighting functions are executed in cooperation with the lighting gateway, while the HVAC controller passively reads room occupancy data and temperature data obtained from the sensor bundles of the network nodes, and also controls blinds and HVAC sensors or actuators. The HVAC controller may also connect to a higher-level building maintenance service (BMS) system and is configured to also send lighting overriding commands in emergency situations (i.e., the HVAC system may instruct, for example, to turn on some or all of the lighting fixtures). If the lighting gateway becomes unavailable, the lighting nodes begin operating in a distributed mode and communicate directly with each other to share occupancy events. If the HVAC controller becomes unavailable, the lighting nodes begin operating in a distributed mode and can share their respective temperature readings with each other, determine the average room temperature, and store that temperature so that the HVAC controller can retrieve it later once it becomes available again. In this way, when the HVAC controller becomes operational again, it can quickly retrieve (albeit aggregated) past data. If the HVAC controller goes missing, the lights can also adjust their lighting control scheme so that the lights in the office's emergency exit paths are not completely turned off, but only dimmed to 20% of their light output, because the emergency lighting override via the HVAC controller is currently not working.

[0093] Similarly, during normal operation, the lighting gateway can communicate with the HVAC controller to coordinate control of the blinds. If the HVAC controller becomes unavailable, the lighting nodes can communicate directly with the blind controller to ensure appropriate degradation of the blinds.

[0094] Figure 2 and Figure 3 Schematic block diagrams of two different embodiments of network nodes, 200 and 300, are shown respectively. The following discussion will focus on... Figure 1 Network node 100 Figure 2 Network node 200 and Figure 3 The characteristics that differ between network nodes 300 are as follows. Except for the first number, the characteristics shared by the network nodes are referred to using the same numbers, where the first number is "1" for network node 100, "2" for network node 200, and "3" for network node 300.

[0095] Network node 200 includes an application control center detection unit 208, configured to determine the availability or unavailability of one or more application control centers in the wireless communication network and provide a corresponding availability signal to the network node's input interface 204. In this particular network node, the determination of application control center unavailability is performed at a network monitoring unit 210, which is configured to monitor wireless communication signals and use the monitored wireless communication signals according to a predetermined algorithm to determine the availability or unavailability of the application control center. For example, the network monitoring unit is configured to detect certain anomalies in network traffic associated with missing or unavailable application control centers. These anomalies include, for example, detecting excessive routing requests or other discovery messages, detecting so-called "last-ditch" messages from application control centers (either directly provided by the application control center or via another node in the wireless communication network), detecting lost link status messages, detecting certain events from other nodes in the wireless communication network, etc. In the network node 200, the transmitting unit and receiving unit of the application unit 202 together form a transceiver unit. The network monitoring unit is connected to the transceiver unit to monitor the wireless communication signal. The wireless communication signal does not need to be specifically addressed to the network node and can be monitored using "promiscuous mode".

[0096] Figure 3 A schematic block diagram of another embodiment of network node 300 is shown. The network node includes a storage unit 312 that stores network data indicating network nodes within a wireless communication network. The network data includes one or more application control entries associated with a corresponding application control center. The network data may include routing data indicating available communication routes within the wireless communication network. The routing data includes one or more control node entries related to the communication route between network node 300 and the application control center. Application unit 302 is connected to the storage unit and configured to provide a first application-specific wireless communication signal based on the network data or routing data. Furthermore, operation control unit 306 is configured to disable application unit access to control node entries for a predetermined time span in a distributed operation mode.

[0097] Routing data includes one or more of the following: bindings, routing table entries, neighbor table entries, address mapping entries, etc., or any combination thereof. Furthermore, the selection of a predetermined time span can result in temporarily disabling access to control node entries, or permanently disabling such access by, for example, deleting the entry.

[0098] Figure 4 A schematic block diagram of yet another embodiment of a network node is shown. The following discussion will focus on... Figure 1 , 2 And network nodes 100, 200 and 300 and 3 Figure 4The characteristics that differ between network nodes 400 are as follows. Except for the first number, the characteristics shared by network nodes 100, 200, 300 and 400 are referred to by the same number, where the first number is "1" for network node 100, "2" for network node 200, "3" for network node 300 and "4" for network node 400.

[0099] Network node 400 includes a receiver unit 403 for receiving wireless communication signals from an application control center of the wireless communication network. The receiver unit 403, together with the transmitter unit of application unit 402, forms a transceiver unit 401 of the network node, configured to provide and receive wireless communication signals. The network node also includes a functional unit connected to the receiver unit and configured to perform wirelessly controllable node functions. In the case of network node 400, the functional unit is a lighting unit 414. The lighting unit can be wirelessly controlled using application-specific wireless communication signals within the wireless communication network. Network node 400 also includes a user input interface 413 for receiving user input signals. Suitable user input interfaces include buttons, switches, controllers, touchpads, etc. Alternatively, additionally, the network node includes a sensing unit, such as a presence or movement sensor, a light sensor, a humidity sensor, etc. Application unit 402 is connected to the user input interface or the sensing unit and is configured to generate and provide a first application-specific wireless communication signal S1 and a second application-specific wireless communication signal S2 based on the received user input signals or sensed parameters.

[0100] The first and second application-specific wireless communication signals generated by the application unit 402 of network node 400 include corresponding control command data for controlling the functional unit 414. For example, when the user input interface is a switch, activating the switch in centralized operation mode causes the application unit to provide the first application-specific wireless communication signal to the application control center, which is assumed to be available. The application control center receives the first communication signal indicating the switch status and generates and outputs instructions for controlling the lighting unit 414, which are received by the receiver unit 403 of the network node. The application unit 402 is also configured to provide the second communication signal directly to the functional unit for performing node functions when operating in distributed operation mode. This is preferably accomplished via a wired connection.

[0101] Figure 5A flowchart illustrating an embodiment of a method 500 for operating a network node to communicate within a wireless communication network is shown. The method includes, in step 502, generating and providing application-specific wireless communication signals for reception within the wireless communication network. The method further includes, in step 504, receiving a corresponding availability signal indicating the availability or unavailability of one or more application control centers used to centrally control data exchange regarding corresponding predetermined application functions within the wireless communication network. The method further includes, in step 506, when an availability signal indicates the unavailability of an application control center, switching the operation of the network node's application unit from a centralized operation mode to a distributed operation mode with respect to the corresponding application control center. The network node's application unit is configured to perform one or more predetermined application functions and generate and provide application-specific wireless communication signals for reception within the wireless communication network. Operation with respect to the corresponding predetermined application function in centralized operation mode includes generating a first application-specific wireless communication signal for communication via the corresponding application control center. Operation with respect to the corresponding predetermined application function in distributed operation mode includes generating a second application-specific communication signal for direct communication with at least one target network node and directly sending them to one or more of the at least one target network node.

[0102] Figure 6 A flowchart illustrating an embodiment of a method 600 for operating a wireless communication network is shown. The method includes performing... Figure 5 Method 500. The method further includes, when operating in a centralized operation mode with respect to a corresponding predetermined application function, in step 602, receiving a first application-specific wireless communication signal as an input wireless communication signal from a network node, the input wireless communication signal including a payload indicating control instructions for controlling the operation of one or more target network nodes, and in step 604, providing an output wireless communication signal including the control instructions to one or more target network nodes.

[0103] In summary, the present invention relates to a network node for communication in a wireless communication network, the network node comprising application units for performing one or more predetermined application functions. The network node includes an input interface for receiving an availability signal indicating the availability or unavailability of a corresponding application control center, for centralized control of data exchange regarding the corresponding application function. An operation control unit is configured to switch the operation of the application unit from a centralized operation mode to a distributed operation mode when the availability signal indicates the unavailability of the corresponding application control center, thereby implementing an alternative operation mode in which, instead of providing a first wireless communication signal to the application control center, a second communication signal is directly transmitted to one or more target network nodes.

[0104] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments in practicing the claimed invention.

[0105] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0106] A single unit or device can perform the functions of several items listed in the claims. The mere fact that certain measures are referenced in mutually different dependent claims does not imply that a combination of these measures cannot be used advantageously.

[0107] Computer programs can be stored / distributed on suitable media, such as optical storage media or solid-state media, provided together with or as part of other hardware; but they can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0108] Any reference numerals in the claims should not be construed as limiting the scope.

Claims

1. A network node for communication in a wireless communication network, the network node comprising: an application unit configured to perform one or more predetermined application functions and to generate and provide application wireless communication signals related to predetermined application functions for reception within the wireless communication network; an input interface configured to receive a respective availability signal indicative of availability or unavailability of one or more application control centers for centralized control of data exchange within the wireless communication network with respect to a respective predetermined application function; an operation control unit connected to the input interface and configured to switch operation of the application unit from a centralized operation mode to a distributed operation mode with respect to a respective predetermined application function upon determining that the availability signal indicates unavailability of the respective application control center; wherein in the centralized operation mode with respect to the respective predetermined application function, the application unit is configured to generate first application wireless communication signals related to the respective predetermined application function for communication via the respective application control center; and in the distributed operation mode with respect to the respective predetermined application function, the application unit is configured to generate second application communication signals related to the respective predetermined application function for direct communication with at least one target network node within the wireless communication network and to send them directly to one or more of the at least one target network node; wherein the network node further comprises: a storage unit for storing network data indicative of the network nodes of the wireless communication network, the network data comprising one or more application control center entries related to respective application control centers; characterized in that the application unit is connected to the storage unit and configured to provide the first application wireless communication signals in accordance with the network data; and the operation control unit is configured to disable access of the application unit to the application control center entries for a predetermined time span in the distributed operation mode.

2. The network node according to claim 1, wherein the operation control unit is further configured to switch operation of the application unit from the distributed operation mode to the centralized operation mode upon determining that the availability signal indicates availability of the respective application control center when the application unit operates in the distributed operation mode with respect to the predetermined application function.

3. The network node according to claim 1 or 2, further comprising: an application control center detection unit configured to determine availability or unavailability of one or more application control centers within the wireless communication network and to provide the respective availability signal to the input interface.

4. The network node according to claim 3, wherein the application control center detection unit comprises a network monitoring unit configured to monitor application wireless communication signals within the wireless communication network and to determine availability or unavailability of the application control center using the monitored application wireless communication signals in accordance with a predetermined algorithm.

5. The network node according to claim 3, wherein: the application control center detection unit is further configured to determine an expected disconnection time span of the application control center from the wireless communication network and to provide a disconnection time signal indicative thereof; and wherein the operation control unit is further configured to receive the disconnection time signal and to further switch the operation from the respective centralized operation mode to the respective distributed operation mode upon determining that the expected disconnection time span is longer than a predetermined threshold time span amount.

6. The network node according to claim 1 or 2, further comprising: a receiver unit for receiving wireless communication signals from an application control center of the wireless communication network; a functional unit connected to the receiver unit and configured to perform a wireless controllable node function; and wherein the first application wireless communication signals and the second application communication signals generated by the application function comprise respective control data for controlling the functional unit, and wherein the operation control unit is further configured to provide the second application communication signals directly to the functional unit for performing the node function in the distributed operation mode with respect to the respective predetermined application function.

7. The network node according to claim 1 or 2, wherein the second application communication signals are directly transmitted as wireless broadcast or wireless groupcast signals with a predetermined maximum allowed hop count to one or more of the target network nodes when the application unit operates in the distributed operation mode with respect to the predetermined application function.

8. The network node according to claim 1 or 2, further comprising: a user input interface for receiving a user input signal; and wherein, the application unit is connected to the user input interface and configured to generate and provide the first application wireless communication signals and the second application communication signals in dependence on the received user input signal.

9. A wireless communication network comprising: at least one network node according to any one of claims 1 to 8; and at least one application control center configured to receive first application wireless communication signals as input wireless communication signals from the network nodes, the input wireless communication signals comprising a payload indicative of control instructions for controlling the operation of one or more target network nodes, and to provide output wireless communication signals comprising the control instructions to the one or more target network nodes.

10. The wireless communication network according to claim 9, wherein: the at least one application control center is configured to provide an availability signal to an input interface of the at least one network node, the availability signal being indicative of an expected unavailability of the application control center within the wireless communication network; and wherein the operation control unit of the at least one network node is configured to switch the operation of the network node from the centralized operation mode to the distributed operation mode upon receiving the availability signal indicative of the expected unavailability of the application control center.

11. The wireless communication network according to claim 9 or 10, wherein: The application control center, when temporarily disconnected from the wireless communication network, is configured to provide an availability signal to the at least one network node, the availability signal indicating an expected availability of the application control center within the wireless communication network; and wherein The operation control unit is configured to switch the operation of the application unit from the distributed operation mode to the centralized operation mode with respect to a respective application function upon receiving an availability signal indicating an expected availability of the application control center.

12. A method for operating a network node communicating in a wireless communication network, the method comprising: generating and providing application wireless communication signals related to a predetermined application function for reception within the wireless communication network; receiving a respective availability signal indicating an availability or unavailability of one or more application control centers for centralized control of data exchange within the wireless communication network with respect to the respective predetermined application function; switching the operation of an application unit of the network node from a centralized operation mode to a distributed operation mode with respect to the respective predetermined application function upon determining that the availability signal indicates an unavailability of the respective application control center; wherein operating in the centralized operation mode with respect to the respective predetermined application function comprises generating first application wireless communication signals related to the respective predetermined application function for communication via the respective application control center; and operating in the distributed operation mode with respect to the respective predetermined application function comprises generating second application communication signals related to the respective predetermined application function for direct communication with at least one target network node and sending them directly to one or more of the at least one target network node; wherein the network node comprises: a storage unit for storing network data indicative of network nodes of the wireless communication network, the network data comprising one or more application control center entries related to the respective application control center; wherein the application unit is connected to the storage unit and configured to provide the first application wireless communication signals in accordance with the network data; and an operation control unit of the network node is configured to disable access of the application unit to the application control center entries in the distributed operation mode for a predetermined time span.

13. The method according to claim 12, wherein the method further comprises: receiving, from the network node, the first application wireless communication signals as input wireless communication signals when operating in the centralized operation mode with respect to the respective predetermined application function, the input wireless communication signals comprising a payload indicative of control instructions for controlling the operation of one or more target network nodes, and providing output wireless communication signals comprising the control instructions to the one or more target network nodes.

14. A computer program product comprising instructions which, when the computer program product is executed by a computer, cause the computer to carry out the method of claim 12 or 13.

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