TIMING SYSTEM FOR A WIRELESS COMMUNICATION NETWORK - Patent application

Abstract

The present invention relates to a timing system (100) for a wireless communication network (102) comprising a plurality of communication devices (104, 104a, 104b, 104c, 104d). The timing system comprises at least one cluster head device (104b) associated with at least one beaconing cluster member device (104c) configured to transmit a beacon message. The at least one cluster head device (104b) and the associated at least one beaconing cluster member device (104c) belong to the plurality of communication devices (104, 104a, 104b, 104c, 104d) of the wireless communication network (102). The at least one beaconing cluster member device (104c) is configured to periodically transmit a periodic message to the cluster head device (104b). The periodic message includes timing information indicating a timing of a next beacon message of the beaconing cluster member device (104c) transmitting the periodic message. The present invention also relates to a timing method for a wireless communication network (102), a beaconing cluster member device (104c) for a wireless communication network (102), a timing method for a beaconing cluster member device (104c), a computer program (546), and a tangible, non-volatile computer readable medium.

Description

[Technical field]

[0001] The present invention relates generally to the technical field of wireless communication networks, and more particularly to timing of beacon messages in wireless communication networks. [Background technology]

[0002] In general, in a wireless communication system, a timing schedule is defined for communication devices of the wireless communication system to save energy and avoid transmission collisions. For example, in a point-to-point topology and a star topology, a timing schedule is generally defined by a communication device acting in a master role or an access point role. However, in a wireless communication system without a communication device acting in a master or access point role, such as a distributed multi-hop topology and a mesh topology, a synchronization technique based on a timing schedule may not be generally available or may be at least limited.

[0003] In a multi-hop topology, a communication device may benefit from periodically collecting information from beacon messages broadcast by neighboring communication devices. One or more of the neighboring communication devices broadcasting the beacon messages may be member devices associated with the communication device collecting the information. In general, however, the neighboring communication devices broadcast their beacon messages at times independently selected by the device itself. The neighboring communication devices may also transmit their beacon messages on frequency channels independently selected by the device itself. Therefore, it is very inefficient in terms of time and energy usage for a communication device to look for beacon messages from neighboring communication devices, even if those neighboring communication devices are member devices associated with the communication device collecting the information. Summary of the Invention [Means for solving the problem]

[0004] The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of example embodiments of the invention.

[0005] An object of the present invention is to provide a timing system, a timing method, a beaconing cluster member device, a computer program, and a computer readable medium for a wireless communication network. Another object of the present invention is to provide a timing system, a timing method, a beaconing cluster member device, a computer program, and a computer readable medium for a wireless communication network that effectively enables information sharing from the beaconing cluster member devices to their respective cluster head devices.

[0006] The object of the invention is achieved by a timing system, a timing method, a beaconing cluster member device, a computer program and a computer readable medium as defined by the respective independent claims.

[0007] According to a first aspect, a timing system for a wireless communication network comprising a plurality of communication devices is provided, the timing system comprising at least one cluster head device associated with at least one beaconing cluster member device configured to transmit a beacon message, the at least one cluster head device and its associated at least one beaconing cluster member device belonging to the plurality of communication devices of the wireless communication network, the at least one beaconing cluster member device configured to periodically transmit a periodic message to its cluster head device, the periodic message including timing information indicating the timing of a next beacon message of the beaconing cluster member device transmitting the periodic message.

[0008] In response to receiving a periodic message from at least one associated beaconing cluster member device, the cluster head device may be configured to adjust a receiving window margin for receiving a next beacon message from the at least one beaconing cluster member device based on timing information included in the received periodic message.

[0009] Alternatively or additionally, at least one beaconing cluster member device may be configured to transmit a next periodic message to its cluster head device in response to detecting that a drift (deviation) in its beacon timing meets a drift threshold.

[0010] At least one beaconing cluster member device may be configured to define its beacon timing drift based on the beacon timing drift of the cluster head device and the elapsed time since the beaconing cluster member device transmitted a previous periodic message to the cluster head device.

[0011] Alternatively or additionally, at least one beaconing cluster member device may be configured to transmit a next periodic message to a cluster head device in response to receiving a beacon message from the cluster head device including a request to transmit the next periodic message.

[0012] The periodic message may be an association request message.

[0013] The association request message may be an association request message related to Digital European Cordless Telecommunication 2020 (DECT-2020).

[0014] Alternatively or additionally, at least one beaconing cluster member device may be further configured to transmit neighbor timing information to its cluster head device indicating the timing of next beacon messages of one or more neighboring devices of the at least one beaconing cluster member device, where the one or more neighboring devices belong to a plurality of communication devices of the wireless communication network.

[0015] At least one beaconing cluster member device may be configured to transmit neighbor timing information to its cluster head device by including the neighbor timing information in a next beacon message to be transmitted.

[0016] According to a second aspect, a timing method for a wireless communication network having a plurality of communication devices is provided, the method comprising: presenting at least one cluster head device associated with at least one beaconing cluster member device configured to transmit a beacon message, where the at least one cluster head device and its associated at least one beaconing cluster member device belong to a plurality of communication devices of the wireless communication network; and periodically transmitting, by the at least one beaconing cluster member device, a periodic message to the cluster head device, where the periodic message includes timing information indicating the timing of a next beacon message of the beaconing cluster member device transmitting the periodic message.

[0017] According to a third aspect, a beaconing cluster member device for a wireless communication network is provided, the beaconing cluster member device comprising a controller and a radio for operating as a wireless node device, the beaconing cluster member device configured to transmit a beacon message and to periodically transmit a periodic message to its cluster head device by the radio, the periodic message including timing information indicating the timing of a next beacon message of the beaconing cluster member device transmitting the periodic message.

[0018] According to a fourth aspect, a timing method for the aforementioned beaconing cluster member device is provided, the method including a step of periodically transmitting a periodic message by a wireless communication device of the beaconing cluster member device to its cluster head device, the periodic message including timing information indicating the timing of the next beacon message of the beaconing cluster member device transmitting the periodic message.

[0019] According to a fifth aspect, there is provided a computer program comprising instructions which, when the computer program is executed by a computer, cause the computer to perform at least the steps of the method set out above.

[0020] According to a sixth aspect, there is provided a tangible, non-volatile computer readable medium containing a computer program as previously described.

[0021] Various exemplary and non-limiting embodiments of the present invention, both as to structure and method of operation, together with additional objects and advantages thereof, can be best understood from the following description of specific exemplary and non-limiting embodiments when read in connection with the accompanying drawings.

[0022] The verbs "to comprise" and "to include" are used in this specification as open limitations which neither exclude nor require the presence of unrecited features. Features recited in the dependent claims may be freely combined with each other, unless expressly stated otherwise. Furthermore, it is to be understood that throughout this specification the use of "a" or "an", i.e. the singular, does not exclude a plurality.

[0023] Embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. [Brief description of the drawings]

[0024] [Figure 1A] 1 illustrates an example of a timing system in a wireless communication environment. [Figure 1B] 1 illustrates a schematic diagram of an example timing system in a wireless communication network environment implemented in a cluster tree topology. [Diagram 2] 1 illustrates an example of an association process between an associating device and a cluster head device. [Figure 3A] 1 illustrates generally a flow chart of an example of a timing method. [Figure 3B]1 illustrates generally an example flow chart of defining an interval between the transmission of a previous periodic message and the transmission of a next periodic message; [Figure 4] 1 illustrates a schematic non-limiting example format of an association request message. [Diagram 5] 1 illustrates a schematic diagram of an example of operational parts of a wireless communication device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] 1 illustrates an example of a timing system 100 operating in a wireless communication environment. The environment includes a wireless communication network (system) 102 that includes multiple wireless communication devices (nodes) 104. The devices 104 operate in the same spectrum, including one or more frequency bands, e.g., in the same geographic region within the presented environment. Each of the one or more frequency bands may include one or more frequency channels. The use of the same spectrum enables two-way wireless communication between the devices 104 in the network 102, such that a wireless transmission transmitted by one device 104 can be received by another device 104 and vice versa.

[0026] The system 100 can be applied to any wireless communication network 102 that uses packet transmission in communication, i.e., in data exchange. Preferably, the system 100 can be applied to any wireless communication network that can be used for multi-hop communication between devices 104. That is, packets can be delivered on at least two consecutive wireless links. The system 100 can be applied to wireless communication networks 102 that comply with the Digital European Cordless Telecommunications (DECT-2020) standard. Some non-limiting examples to which the system 100 can also be applied include, but are not limited to, wireless multi-hop networks, wireless mesh networks, such as wireless sensor networks (WSNs), Bluetooth Low Energy (BLE) mesh networks, Zigbee networks, Thread networks, public land mobile networks (PLMNs), wireless local area networks (WLANs), low power wide area networks (LPWANs), cellular-based local area networks, cellular networks, and / or any other wireless networks. An example of a WSN is described in U.S. Pat. No. 7,830,838.

[0027] The DECT-2020 standard is a radio access technology developed by ETSI. DECT-2020 supports massive machine type communication (mMTC) and ultra-reliable low latency communication (URLLC). At the physical (PHY) layer, the key technical components of DECT-2020 are orthogonal frequency division multiplexing (OFDM), adaptive modulation and coding schemes (MCS), advanced channel coding methods (turbo, LDPC, convolutional coding), hybrid automatic repeat request (HARQ) for both scheduled and contention-based transmissions, and support for multi-antenna transmission with different multiple-input multiple-output (MIMO) streams. At the Medium Access (MAC) layer and systems side, key technology components of DECT-2020 are support for a large number of Internet of Things (IoT) sensors, actuators, and other industrial applications, support for mesh network topologies, support for URLLC communications with very low latency (a typical application example could be wireless microphones), operation in license-exempt frequencies, and support for multiple overlapping non-cooperative networks with cognitive radio capabilities to share spectrum resources between multiple networks.

[0028] As mentioned above, each device 104 can provide two-way wireless communication with at least one other device 104 by means of its radio 536. This means that each device 104 can operate as a transmitter, a receiver, or a transmit-receiver, where each device 104 is capable of transmitting at least one message to other devices 104 and receiving at least one message from other devices 104 in the network 102.

[0029] The network 102 may also include at least one gateway device 105, e.g., one, two, three, four, or more gateway devices. Each gateway device 105 acts as a gateway between the network 102 and other external networks 106, e.g., the Internet, and distributes data in and out of the network 102. Each gateway device 105 communicates with at least one sink device (node) 104a, e.g., one, two, three, four, or more sink devices, each of which acts as a wireless interface to the gateway device 105 in the network 102. The at least one sink device 104a belongs to a plurality of devices 104 of the network 102. Each sink device 104a may be physically connected to the gateway device 105 or may be located separately in different parts of the network 102. If the gateway 105 comprises several sink devices 104 a , one may be located in connection with the gateway device 105 and others may be located separately in different parts of the network 102 .

[0030] The sink device 104a is a fixed router device (router), while the other node devices 104 can operate in different fixed or non-fixed roles in the network 102. The other devices 104 in the system 100 are router devices, i.e. devices operating in a router role, and non-router devices, i.e. devices operating in a non-router role, depending on whether the device 104 needs to participate in data forwarding. One method for selecting the router and non-router roles can follow, for example, the method described in U.S. Patent Application Publication No. 10,499,264.

[0031] Each router device 104 maintains connectivity for the network 102 and routes data for other devices 104 as needed. Each non-router device 104, like the sink and router devices 104, can provide two-way communication to transmit its own data and receive data directed to it, but the non-router devices do not route data for other devices 104. Each device 104 may be capable of operating at least as a router or a non-router device. Alternatively, at least some of the devices 104 may be capable of operating as a router or a non-router device, and one or more of the devices 104 may be capable of operating only as a router device or only as a non-router device.

[0032] The network 102 includes devices 104 such that not all devices 104 can communicate directly with the sink device 104a (gateway device 105) due to radio conditions, e.g., wide distances between the devices 104, interference or signal fading between the devices 104, and limited radio range, and requires the use of multi-link (multi-hop) communication between each device 104 and the sink device 104a.

[0033] The network 102 may be implemented in a cluster tree topology, and the network 102 comprises at least one cluster 108. The at least one cluster 108a-108c may be formed dynamically or statically. Each cluster 108a-108c may comprise a cluster head device 104b and at least one cluster member device 104c, 104d. The at least one cluster member device 104c, 104d belongs to the cluster 108a-108c and is associated with the cluster head device 104b to operate as at least one cluster member device 104c, 104d. One or more cluster member devices 104c of the clusters 108a-108c may also operate as a cluster head device 104b for other clusters 108a-108c of the network 102. In other words, one or more clusters 108a-108c may each include one or more cluster member devices 104c that can also act as cluster head devices 104b for other clusters 108a-108c in the network 102. In yet another way, one or more cluster member devices 104c may simultaneously act in two different roles, i.e., a cluster member role in one cluster 108a-108c and a cluster head role in another cluster 108a-108c. When acting in two roles, each cluster member device 104c can perform one or more operations of only one role at a time, i.e., only one or more operations of a cluster member role in one cluster 108a-108c or only one or more operations of a cluster head role in the other cluster 108a-108c. A router device can act as a cluster head device 104b and / or a cluster member device 104c. A non-router device can act as a cluster member device 104d.Thus, each cluster 108a-108c of the network 102 may include at least one cluster member device 104c (i.e., a router cluster member device) configured to transmit beacon messages, i.e., at least one beaconing cluster member device 104c and / or at least one cluster member device 104d (i.e., a non-router cluster member device). The sink device 104a may also operate as a cluster head device 104b.

[0034] FIG. 1B illustrates a schematic diagram of an example of a timing system 100 operating in a wireless communication network 102 implemented in a cluster tree topology. The timing system 100 and network 102 of FIG. 1B are similar to the timing system 100 and network 102 of FIG. 1A, but FIG. 1B illustrates the cluster tree topology of the network 102 in more detail. In the example of FIG. 1B, the network 102 includes three clusters 108a-108c, each of which includes one cluster head device 104b and at least one cluster member device 104c, 104d. The cluster 108a of the example of FIG. 1B includes a cluster head device 104b, one cluster member device 104d operating as a non-router device, and two beaconing cluster member devices 104c. The example cluster 108b of FIG. 1B includes a cluster head device 104b, one cluster member device 104d acting as a non-router device, and one beaconing cluster member device 104c. The example cluster 108c of FIG. 1B includes a cluster head device 104b and two cluster member devices 104d acting as non-router devices. The beaconing cluster member device 104c of the cluster 108a acts as a cluster head device 104b of the other clusters 108b, 108c. That is, one beaconing cluster member device 104c of the cluster 108a acts as a cluster head device 104b of the cluster 108b, and the other beaconing cluster member device 104c of the cluster 108a acts as a cluster head device 104b of the cluster 108c. Therefore, the reference numerals 104c / 104b are used for these two devices in FIG. 1B. FIG. 1B shows only one non-limiting example, and the network 102 may also include any other number of clusters 108a-108c, and each cluster 108a-108c may include any other number of cluster member devices 104c, 104d.

[0035] Each router device and each sink device 104a of the network 102 is configured to periodically transmit a beacon message to provide the possibility for other devices 104 to associate with other devices in data routing and provide services to other devices 104. The beacon message may comprise a cluster beacon message and / or a network beacon message. The cluster beacon message may include frame information, slot timing information, radio parameter information, and / or radio resource information. The information included in the cluster beacon message (e.g., frame information, slot timing information, radio parameter information, and / or radio resource information) may include information of the device 104 transmitting the cluster beacon message itself. Furthermore, the information included in the cluster beacon message (e.g., frame information, slot timing information, radio parameter information, and / or radio resource information) may include information of one or more neighboring devices of the device 104 transmitting the cluster beacon message. The cluster beacon message may be used to provide frame information and slot timing information to the clusters 108a-108c. Alternatively or additionally, the cluster beacon message may be used to inform other devices 104 of radio parameter information and radio resource information so that they can communicate with the sink device 104a. The network beacon message may include information indicating the presence of a network and / or information indicating the timing, periodicity, and / or operating channel of the transmission of the cluster beacon message. The information included in the network beacon message (e.g., information indicating the presence of a network and / or information indicating the timing, periodicity, and / or operating channel of the transmission of the cluster beacon message) may include information of the device 104 transmitting the cluster beacon message itself. Furthermore, the information included in the network beacon message (e.g., information indicating the presence of a network and / or information indicating the timing, periodicity, and / or operating channel of the transmission of the cluster beacon message) may include information of one or more neighboring devices of the device 104 transmitting the cluster beacon message.

[0036] The term "neighboring device" throughout this application refers to a device 104 whose transmissions can be correctly received by a receiving device. The expanded meaning of the term "neighboring wireless device" takes into account neighbors of adjacent (adjacent) wireless devices, i.e., multi-hop neighbors, such as two-hop neighbors, three-hop neighbors, four-hop neighbors, etc. The term "neighboring device" throughout this application refers to one or more devices 104 whose transmissions can be correctly received by a receiving device 104. The expanded meaning of the term "neighboring device" takes into account neighbors of adjacent devices, i.e., multi-hop neighbors, such as two-hop neighbors, three-hop neighbors, four-hop neighbors, etc.

[0037] The system 100 is used for timing of beacon messages in a wireless communication network 102. The system 100 comprises at least one cluster head device 104b associated with at least one beaconing cluster member device 104c configured to transmit a beacon message. The beacon message transmitted by the beaconing cluster member device 104c is primarily indented to the possible cluster member devices 104c, 104d of the beaconing cluster member device 104c (if the beaconing cluster member device 104c also serves as a cluster head device 104b of another cluster 108a-108c), but other devices 104 within the neighbors of the beaconing cluster member device 104c, including the cluster head device 104b associated with the beaconing cluster member device 104c, can receive the beacon message transmitted by the beaconing cluster member device 104c. At least one cluster head device 104b and at least one associated beaconing cluster member device 104c belong to a plurality of communication devices 104 of the network 102. In this application, the system 100 is described hereafter mainly using one cluster head device 104b associated with one beaconing cluster member device 104c belonging to the system 100 and operating in the network 102 and forming a group of devices 104b, 104c. However, these devices 104b, 104c correspond to the device 104. The system 100 may also include a plurality of other devices 104, 104a, 104d that also participate in forming said group, in which case the group includes the devices 104, 104a, 104b, 104c, 104d.

[0038] To become a cluster member device 104c, 104d of a cluster 108a-108c, the device 104 needs to be associated with a cluster head device 104b of the cluster 108a-108c. That is, the cluster member devices 104c, 104d are associated with the cluster head device 104b. FIG. 2 shows an example of an association process 210 between an associated device (AD) 104 and a cluster head device (CHD) 104b. The association 210 may include the associated device 104 receiving a cluster beacon (CB) message from the cluster head device 104b and the associated device 104 sending an association request (AR) message to the cluster head device 104b. The association request message may include timing information indicating the timing of the next beacon message to be transmitted by the associated device 104, i.e., the beacon timing of the associated device 104, and frequency information indicating the frequency channel of the next beacon message to be transmitted by the associated device 104. The beacon timing of the associated device 104 is indicated in Figure 2 by the term "Time Until Next CB". The association 210 may further include the cluster head device 104b sending an Association Request Response (ARR) message to the associated device 104 indicating either an acceptance or rejection of the association request. If the association is accepted, the associated device 104 becomes a cluster member device 104c, 104d of the clusters 108a-108c, and the cluster head device 104b and the cluster member devices 104c, 104d become associated. In this example, the associated device 104 becomes a beaconing cluster member device 104c.

[0039] 2 further illustrates a first exemplary communication 220 between associated device 104c and cluster head device 104b, where cluster head device 104b receives a cluster beacon (CB) message transmitted by associated device 104 (which is beaconing cluster member device 104c) without time drift (or with little time drift) after association. Since associated device 104 is now beaconing cluster member device 104c, in the remainder of the description of this example, the term beaconing cluster member device 104c is used to mean associated associated device 104. All cluster beacon (CB) messages transmitted by beaconing cluster member device 104c to cluster head device 104b do not necessarily contain useful information. Thus, the cluster head device 104b does not spend time and energy listening to all cluster beacons, and therefore the cluster head device 104b begins to drift from the beacon timing of the beacon member device 104c as indicated by the timing information included in the association message received from the beacon member device 104c. In the second exemplary communication 230 between the beacon member device 104c and the cluster head device 104b, the cluster head device 104b begins to drift from the beacon timing of the beacon member device 104c as indicated by the timing information included in the association message received from the beacon member device 104c. Similarly, the beacon member device 104c also begins to drift from the beacon timing of the cluster head device 104b. The (time) drift (d) in the example of FIG. 2 represents the drift of the beacon timing of the beacon member device 104c relative to the cluster head device 104b.In order for the cluster head device 104b to be able to receive the cluster beacon message (CB) from the beginning of the cluster beacon message (CB), it needs to start receiving the beacon message (CB) from the beaconing cluster member device 104c with a time drift (d) (i.e., a duration corresponding to the drift) earlier than indicated by the timing information included in the association message. If the drift (d) becomes large, the cluster member device 104c may also change its frequency channel used to transmit the cluster beacon message, and thus it becomes inefficient for the cluster head device 104b to look for the cluster beacon message transmitted by the beaconing cluster member device 104c. The beacon timing, drift, and / or any other timing information is valid at a defined time and starts to change after it is defined. In other words, the sense of time of the cluster head device 104b and the beaconing cluster member device 104c is not absolute, and the time information of both devices 104b, 104c changes compared to the ideal timing information and compared to each other's timing information.

[0040] FIG. 3A illustrates generally an example of a timing method for timing beacon messages in a wireless communication network 102 according to the aforementioned timing system 100. FIG. 3A illustrates the timing method as a flow chart. The method is primarily described by using the system 100 with one cluster head device 104b associated with one beaconing cluster member device 104c. The system 100 may further comprise at least one other cluster head device 104b, e.g., one, two, three, four or more other cluster head devices, each cluster head device 104b associated with at least one beaconing cluster member device 104c, e.g., one, two, three, four or more beaconing cluster member devices. Although this method is described using a system 100 having one cluster head device 104b and one beaconing cluster member device 104c, each cluster head device 104b of the system 100 may be independently configured to perform one or more method steps (i.e., operations) of the cluster head device 104b as described for the one cluster head device 104b, and each beaconing cluster member device 104c of the system 100 may be independently configured to perform one or more method steps (i.e., operations) of the beaconing cluster member device 104c as described for the one beaconing cluster member device 104c.

[0041] In step 310, the beaconing cluster member device 104c periodically transmits a periodic message to its cluster head device 104b. The periodic message includes timing information indicating the timing of the next beacon message of the beaconing cluster member device 104c transmitting the periodic message, i.e., the beacon timing of the beaconing cluster member device 104c. The beacon timing indicates the timing of the next beacon message of the beaconing cluster member device 104c that transmitted the periodic message. If a cluster 108a-108c includes multiple beaconing cluster member devices 104c, each of the beaconing cluster member devices 104c of the clusters 108a-108c periodically transmits a periodic message to its cluster head device 104b, i.e., the respective cluster head device 104b, i.e., the cluster head device 104b of the cluster 108a-108c that includes the beaconing cluster member device 104c. When the system 100 includes multiple cluster head devices 104b (i.e., two or more clusters 108a-108c), at least one beaconing cluster member device 104c of each cluster 108a-108c periodically transmits a periodic message to its cluster head device 104b belonging to the same cluster 108a-108c. The periodic message may further include frequency information indicating a frequency channel of the next beacon message transmitted by the beaconing cluster member device 104c. The beacon message may be, for example, a cluster beacon message. The beaconing cluster member device 104c periodically transmits a periodic message to its cluster head device 104b, thereby effectively sharing information from the beaconing cluster member device 104c to each cluster head device 104b. This eliminates the need for the cluster head device 104b to repeatedly scan (on different frequency channels) to find the beacon message transmitted by at least one beaconing cluster member device 104c.Additionally, it may avoid the need for the beaconing cluster member device 104c to repeat the actual beacon content to its cluster head device using point-to-point communication. The actual beacon content may include, for example, an identification of the transmitting device (e.g., a network ID and / or a transmitter address), timing information, and / or allocation information (e.g., a resource allocation information element (IE), a random access resource IE, a broadcast indication IE, and / or a neighbor IE).

[0042] The periodic message may be an association request message 400. That is, the beaconing cluster member device 104c may periodically reassociate with the cluster head device 104b by sending the association request message 400 to the cluster head device 104b. Reassociation is a lightweight task for the beaconing cluster member device 104c since the beaconing cluster member device 104c is configured to follow the beacon timing of the cluster head device 104b by receiving the cluster beacon message transmitted by the cluster head device 104b anyway. By receiving the cluster beacon message transmitted by the cluster head device 104b, the beaconing cluster member device 104c knows that the cluster head device 104b is still present and / or whether the cluster head device 104b has information to transmit to the beaconing member device 104c. Alternatively or additionally, if the beaconing cluster member device 104c has information to transmit to the cluster head device 104b, the received cluster beacon message includes reception timing information indicative of when the cluster head device 104b can receive any information from the beaconing cluster member device 104c. However, if the beaconing cluster member device 104c is unable to receive the cluster beacon message from the cluster head device 104b for any reason, for example, due to a change in the location of the cluster head device 104c and / or a change in the frequency channel used to transmit the cluster beacon message, the beaconing cluster member device 104b can receive network beacon messages on a common network channel to attempt to find and / or associate with another cluster head device 104b.Furthermore, in the absence of actual data traffic between the beaconing cluster member device 104c and the cluster head device 104b, the beaconing cluster member device 104c needs to periodically indicate its presence to the cluster head device 104b to avoid losing its membership due to, for example, a timeout. This allows periodic messaging (e.g., in the form of reassociation) to be nearly free, since the beaconing cluster member device 104c would anyway need to perform signaling to the cluster head device 104b to maintain its membership. The association request message 400 may be, for example, a DECT-2020 association request message. In other words, the association request message 400 may be an association request message defined in the DECT-2020 medium access control (MAC) specification. FIG. 4 illustrates a non-limiting example of a format of the association request message 400. The exemplary association request message 400 of FIG. 4 is a DECT-2020 association request message. Definitions of the fields of the exemplary association request message 400 of FIG. 4 are defined in Table 1.

[0043] [Table 1]

[0044] In step 320, in response to receiving the periodic message from the beaconing cluster member device 104c, the cluster head device 104b can adjust a receiving window margin for receiving a next beacon message from the beaconing cluster member device 104c based on the timing information included in the received periodic message. This allows the cluster head device 104b to efficiently know the start of the next cluster beacon transmitted by the beaconing cluster member device 104c. If the cluster head device 104b is associated with multiple beaconing cluster member devices 104c, the cluster head device 104b can adjust its receiving window margin for receiving a next beacon message from each beaconing cluster member device 104c separately based on the timing information included in the periodic message received from each beaconing cluster member device 104c. In other words, the cluster head device 104b may have separate receive window margins for receiving beacon messages from the multiple beaconing cluster member devices 104c, and the cluster head device 104b may adjust each receive window margin separately based on the timing information included in the periodic messages received from the respective beaconing cluster member devices 104c. Alternatively, the cluster head device 104b may have a common receive window margin for receiving beacon messages from the multiple beaconing cluster member devices 104c with which the cluster head device 104b is associated. In that case, the cluster head device 104b may adjust its common receive window margin for receiving the next beacon message from the multiple beaconing cluster member devices 104c based on the timing information included in the periodic messages received from the multiple beaconing cluster member devices 104c.

[0045] In response to detecting that the drift (d) of its beacon timing meets the drift threshold, the beaconing cluster member device 104c can transmit a next periodic message to its cluster head device 104b. In other words, the beaconing cluster member device 104c can define an interval between the transmission of the previous periodic message and the transmission of the next periodic message based on detecting that the drift of the beacon timing of the beaconing cluster member device 104c meets the drift threshold. The drift threshold can be network specific, i.e., all the beaconing cluster member devices 104c of the network 102 can have the same drift threshold. Alternatively, the drift threshold can be device specific, i.e., one or more beaconing cluster member devices 104c of the network 102 can each have a separate drift threshold. Alternatively, the drift threshold can be a local threshold. Each cluster head device 104b can provide a local threshold to its associated beaconing cluster member device 104c. The local threshold may be the same for all beaconing cluster member devices 104c of the cluster head device 104b, or the cluster head device 104b may provide different local thresholds to one or more of the beaconing cluster member devices 104c. The local threshold allows the cluster head device 104b to control the handling of drift. For example, the local threshold may be included in the beacon message, for example as a bit field, or in a control message, such as an association response message. The drift threshold, together with the drift (d) of the beacon timing of the beaconing cluster member device 104c, defines the interval between the transmission of the previous periodic message and the transmission of the next periodic message. The verb "satisfy" in the context of the drift threshold is used in this patent application to mean that a predetermined condition is satisfied. For example, the predetermined condition may be that a drift threshold has been reached and / or exceeded.FIG. 3B illustrates diagrammatically an example of method steps for defining an interval between the transmission of a previous periodic message and the transmission of a next periodic message.

[0046] In step 330, the beaconing cluster member device 104c defines its beacon timing drift (d). The beacon timing drift of the beaconing cluster member device 104c is a time drift relative to the cluster head device 104b. The beacon timing drift (d) of the beaconing cluster member device 104c can be defined based on, for example, the beacon timing drift of the cluster head device 104b and the elapsed time since the beaconing cluster member device 140c sent a previous periodic message to the cluster head device 104b. The beacon timing drift of the cluster head device 104b is a time drift relative to the beaconing member device 104c.

[0047] Next, an example of defining the beacon timing drift of the cluster head device 104b by the beaconing cluster member device 104c will be described. The beacon timing drift of the cluster head device 104b may also be defined using other definition procedures. The beaconing cluster member device 104c can define the beacon timing drift of the cluster head device 104b from the perspective of the beaconing cluster member device 104c based on the time drift between two consecutive beacon messages received from the cluster head device 104b by first comparing the start times (i.e., beacon timings) of the transmissions of the two consecutive beacon messages received from the cluster head device 104b. The two consecutive beacon messages may be a network beacon message or a cluster beacon message. Alternatively, one of the two consecutive beacon messages may be a network beacon message and the other may be a cluster beacon message, or vice versa. The cluster head device 104b (dCH ) beacon timing drift can be defined, for example, using the following equation:

[0048] d CH =t CB_n -t CB_n-1 (1)

[0049] Here, t CB_n and t CB_n-1 is the start time of the transmission of two consecutive beacon messages, i.e., the beacon timing of two consecutive beacon messages. The defined drift (d CH ) may define the drift of the beacon timing of the cluster head device 104b in parts per million (ppm) relative to the beacon period, i.e., access cycle length, announced by the cluster head device 104b, for example, in a beacon message (cluster beacon message and / or network beacon message) transmitted by the cluster head device 104b. The drift of the beacon timing of the cluster head device 104b (ppm(d CH_ppm ) can be defined, for example, using the following formula:

[0050]

number

[0051] where d CH is the beacon timing drift of the cluster head device 104b defined using equation (1) above, and AL is the access period length reported by the cluster head device 104b. In addition to the beacon timing drift of the cluster head device 104b, the beaconing cluster member device 104c may define the accuracy of the drift in ppm and the timing of the next beacon message sent by the cluster head device 104b. The accuracy of the drift in ppm (d CH_ppm_acc ) can be defined based on the following formula:

[0052]

number

[0053] The timing of the next beacon message transmitted by the cluster head device 104b, i.e., the start time of the transmission of the next beacon message by the cluster head device 104b (t CBnext ) may be defined based on the following formula:

[0054]

number

[0055] Here, t CB is the start time of the previous beacon message transmitted by cluster head device 104b.

[0056] Next, an example of defining the drift of its beacon timing by the beacon cluster member device 104c itself will be described. The beacon cluster member device 104c can define the drift of its beacon timing (d), for example, by using the following formula:

[0057] d=d CH_ppm ×(t now -t previous_PM ) (5)

[0058] where d CH_ppm is the defined drift of the beaconing timing of the cluster head device 104b (d CH_ppm By using the above formula (2) to define d CH_ppm t, or by using any other formula or algorithm for defining now is the current time, and t previous_PMis the timing of the transmission of the previous periodic message by the beaconing cluster member device 104c to the cluster head device 104b. The elapsed time since the transmission of the previous periodic message by the beaconing cluster member device 140c to the cluster head device 104b is t now -t previous_PM It is defined by the formula:

[0059] In step 340, the beaconing cluster member device 104c compares the defined drift (d) of its beacon timing to the drift threshold. If the defined drift (d) meets, i.e., reaches and / or exceeds, the drift threshold, the beaconing cluster member device 104c can transmit the next periodic message to its cluster head device 104b as defined in step 310 above. If the defined drift (d) does not meet the drift threshold, the beaconing cluster member device 104c can continue to define the drift (d) at a later point in time.

[0060] Alternatively or additionally, the beaconing cluster member device 104c may transmit the next periodic message to the cluster head device 104b in response to receiving a beacon message from the cluster head device 104b including a request to transmit the next periodic message to the cluster head device 104b. For example, the cluster head device may detect that it has lost synchronization with the beaconing cluster member device 104c.

[0061] According to an example, the beaconing cluster member device 104c may further transmit neighbor timing information to its cluster head device 104b, indicating the timing of the next beacon message of one or more neighboring devices of the beaconing cluster member device 104c, i.e., the beacon timing of the one or more neighboring devices. The one or more neighboring devices belong to a plurality of communication devices 104 of the wireless communication network 102. For example, the beaconing cluster member device 104c may transmit the neighbor timing information to its cluster head device 104b by including the neighbor timing information in a next beacon message to be transmitted to the cluster head device 104b. The next beacon message is a periodic message transmitted to the cluster head device 104b, e.g., a next beacon message in which the timing information is included in an association message. Alternatively, the beaconing cluster member device 104b may transmit the neighbor timing information to its cluster head device 104b together with the periodic message, e.g., in an association request message. By also transmitting neighbor timing information to the cluster head device 104b by the beaconing cluster member device 104c, the cluster head device 104b can receive timing information regarding a wider group of devices 104 simultaneously.

[0062] 5 illustrates devices 104 (104a, 104b, 104c, 104d) capable of communicating within network 102 and performing the features (steps) associated with the timing method as described above. In other words, device 104 is described as being capable of operating as cluster head device 104b and performing the features of the timing method associated with cluster head device 104b as described above, and / or as beaconing cluster member device 104c and performing the features of the timing method associated with beaconing cluster member 104c. Device 104 can also operate as sink node 104a and / or as cluster member device 104d operating as a non-routing node.

[0063] The device 104 includes a controller 530 that controls the operation of its parts 532, 534, 536, 538, and 540 so that the device 104 operates as described above.

[0064] The controller 530 includes a processor 532 for executing operator initiated instructions and / or computer program initiated instructions and processing data to execute applications. The processor 532 may include at least one processor, for example, one, two, three, four or more processors.

[0065] The controller 530 also includes a memory 534 for storing and maintaining data. The data may be instructions, computer programs, and data files. The memory 534 includes at least one memory, for example, one, two, three, four, or more memories.

[0066] The device 104 also includes a radio 536 and an antenna 538 that the controller 530 uses to transmit commands, requests, messages, and data to at least one of the entities in the system 100, such as the device 104, via the antenna 538. The radio 536 also receives commands, requests, and data from at least one of the entities in the system 100 and / or the network 102, such as the device 104, via the antenna 538. Communications between the radio 536 of the device 104 and other entities in the system 100 and / or the network 102 are provided wirelessly via the antenna 538.

[0067] The device 104 may further include a power supply 540. The power supply 540 includes components for providing power to the device 104, such as a battery and a regulator.

[0068] The memory 534 stores at least a wireless communication application 542 for operating (controlling) the wireless communicator 536 and a power supply application 544 for operating the power supply 540 .

[0069] The memory 534 stores a computer program (computer software, computer application) 546 which, when executed (run) by the controller 530 in a computer, e.g., device 104, uses at least one of the portions 536, 538, 540 to perform at least the operations of the device 104 described above in connection with the previous figures.

[0070] The computer program 546 may be stored on a tangible, non-volatile computer readable storage medium, such as a compact disc (CD) or a universal serial bus (USB) type storage device.

[0071] The specific examples provided in the above description should not be construed as limiting the applicability and / or interpretation of the appended claims. The lists and groups of examples provided in the above description are not exhaustive unless expressly stated.

Claims

1. A timing system (100) for a wireless communication network (102) comprising a plurality of communication devices (104, 104a, 104b, 104c, 104d), the timing system comprising at least one cluster head device (104b) associated with at least one beaconing cluster member device (104c) configured to transmit beacon messages; the at least one cluster head device (104b) and the at least one associated beaconing cluster member device (104c) belonging to the plurality of communication devices (104, 104a, 104b, 104c, 104d) of the wireless communication network (102); the at least one beaconing cluster member device (104c) is configured to periodically transmit a periodic message to a cluster head device (104b), the periodic message including timing information indicating a timing of a next beacon message of the beaconing cluster member device (104c) transmitting the periodic message; A timing system (100).

2. 2. The timing system (100) of claim 1, wherein in response to receiving the periodic message from at least one associated beaconing cluster member device (104c), the cluster head device (104b) is configured to adjust a receiving window margin for receiving the next beacon message from the at least one beaconing cluster member device (104c) based on the timing information included in the received periodic message.

3. The timing system (100) of claim 1 or claim 2, wherein the at least one beaconing cluster member device (104c) is configured to transmit a next periodic message to the cluster head device (104b) in response to detecting that the drift of the beacon timing meets a drift threshold.

4. 4. The timing system of claim 3, wherein the at least one beaconing cluster member device is configured to define a beacon timing drift based on a beacon timing drift of the cluster head device and an elapsed time since the beaconing cluster member device transmitted a previous periodic message to the cluster head device.

5. 5. The timing system of claim 1, wherein the at least one beaconing cluster member device is configured to transmit the next periodic message to the cluster head device in response to receiving a beacon message from the cluster head device including a request to transmit the next periodic message.

6. The timing system (100) of any one of claims 1 to 5, wherein the periodic message is an association request message (400).

7. 7. The timing system of claim 6, wherein the association request message is a Digital European Cordless Telecommunication 2020 (DECT-2020) association request message (400).

8. The timing system of any one of claims 1 to 7, wherein the at least one beaconing cluster member device (104c) is further configured to transmit neighbor timing information to a cluster head device indicating timing of next beacon messages of one or more neighboring devices of the at least one beaconing cluster member device (104c), the one or more neighboring devices belonging to the plurality of communication devices (104, 104a, 104b, 104c, 104d) of the wireless communication network (102).

9. 9. The timing system of claim 8, wherein the at least one beaconing cluster member device (104c) is configured to transmit the neighbor timing information to a cluster head device (104b) by including the neighbor timing information in the next beacon message to be transmitted.

10. A timing method for a wireless communication network (102) comprising a plurality of communication devices (104, 104a, 104b, 104c, 104d), comprising: presenting at least one cluster head device (104b) associated with at least one beaconing cluster member device (104c) configured to transmit beacon messages, the at least one cluster head device (104b) and the associated at least one beaconing cluster member device (104c) belonging to the plurality of communication devices (104, 104a, 104b, 104c, 104d) of the wireless communication network (102); periodically transmitting (310) a periodic message by the at least one beaconing cluster member device (104c) to a cluster head device (104b), the periodic message including timing information indicating a timing of a next beacon message of the beaconing cluster member device (104c) transmitting the periodic message; A timing method including:

11. A beaconing cluster member device (104c) for a wireless communication network (102), comprising: A controller (530); a wireless communication device (536) for operating as a wireless node device; Equipped with The beaconing cluster member device (104c): Send a beacon message, periodically transmitting a periodic message to the cluster head device (104b) via said wireless communication device (536); the periodic message includes timing information indicating a timing of a next beacon message of the beaconing cluster member device (104c) transmitting the periodic message; A beaconing cluster member device (104c).

12. 12. A timing method for a beaconing cluster member device (104c) as described in claim 11, comprising the step of periodically transmitting (310) a periodic message to its cluster head device (104b) by a wireless communication device (536) of the beaconing cluster member device (104c), the periodic message including timing information indicating the timing of a next beacon message by the beaconing cluster member device (104c) transmitting the periodic message.

13. A computer program (546) comprising instructions that, when said computer program is executed by a computer, cause said computer to carry out at least the steps of the method of claim 12.

14. 14. A tangible, non-volatile computer readable medium containing the computer program of claim 13 (546).

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