Methods for locating mobile devices in a UWB localization network

Abstract

Method for locating mobile devices in an ultra-wideband (UWB) localization network, wherein the network is divided into clusters (C) and each cluster (C) has several network nodes (N) such that the network nodes (N) form a meshed network, characterized in that - the network nodes (N) arranged in a cluster (C) synchronize themselves within a cluster (C) in Ultra Wideband (UWB) by sending and receiving synchronization messages with a scrambled timestamp sequence, STS field and a data field, and that - the position of the network nodes (N) in the UWB localization network is known and the network nodes (N) of a cluster (C) generate a cluster position from the positions of the individual network nodes (N) such that - the cluster position for all network nodes (N) of the cluster (C) is used as an input to generate the STS field used in the synchronization message.

Description

[0001] The invention relates to a method for locating mobile devices in a UWB localization network and is particularly used for locating mobile devices indoors.

[0002] GPS cannot be used for positioning in buildings due to roofing. Therefore, networks for positioning mobile devices, especially indoors, that use ultra-wideband (UWB) technology for communication between individual network nodes are known. Such positioning networks typically consist of several stationary nodes, also called satlets or anchors, that form the infrastructure of an indoor positioning environment. Within such an infrastructure, it is possible to locate mobile devices such as tablets or mobile phones or to enable them to locate themselves. This is achieved by sending and / or receiving UWB network messages to or from the infrastructure or indoor positioning environment.

[0003] There are various approaches to exchanging network messages and using them for location purposes. Common methods include two-way ranging (TWR), time difference of arrival (TDoA), or reverse TDoA, which is sometimes referred to as downlink (DL) TDoA. TDoA-based methods require temporal synchronization of the infrastructure with nanosecond accuracy to evaluate the signal propagation times of radio signals, which propagate at the speed of light (1 light nanosecond corresponds to 30 cm).

[0004] Good radio propagation conditions are essential and necessary for wireless infrastructure synchronization. Under real-world conditions, complex building structures complicate the deployment of indoor positioning systems, which must be equipped with a large number of infrastructure nodes and are subject to unpredictable radio propagation conditions. These include shadowing of radio signals and loss of line of sight between nodes, for example, due to walls.

[0005] Due to this fact, complex indoor positioning environments are advantageously divided into clusters with good radio propagation conditions and manageable network sizes, while simultaneously minimizing radio interference between clusters. Furthermore, security aspects must be considered to protect indoor positioning systems from intentional or unintentional interference.

[0006] A method called scrambled timestamp sequence (STS) was introduced and standardized specifically for UWB systems (IEEE 802.15.4z standard). This method enables secure, hardware-based timestamping of network messages, which is essential for network synchronization and the location of mobile devices. Synchronization only occurs with nodes that use an identical STS pattern. The detailed structure of STS can be found in the document IEEE Std 802.15.4z-2020, IEEE Standard for Low-Rate Wireless Networks, Amendment 1: Enhanced Ultra Wideband (UWB) Physical Layers (PHYs) and Associated Ranging Techniques.

[0007] EP 4 054 114 A1 discloses a device and method for generating an encrypted timestamp sequence in a UWB system, according to which roles are assigned to a controller and a controller. This solution has a complex design, as it requires both a UWB communication channel for distance measurement and a non-UWB communication channel for network control or initialization. The non-UWB communication channel can be, for example, a BLE (Bluetooth Low Energy) connection. Furthermore, to secure UWB communication, time-variable STS configurations are required on the devices of a wireless network. These configurations are linked to a time slot, and the transmitter and receiver must have the same understanding of time. Only the time-variable STS is used. A further disadvantage is that the controller represents a single point of failure.

[0008] US 2022 / 0191700 A1 discloses an ultra-wideband communication method and a communication device for securely generating and managing a security key. According to the method, a timestamp is generated based on a first key, with the timestamp being used for the initial communication between the devices. Three parameters are used to generate the timestamp: phyHarpUwbStsKey, phyHrpUwbStsVUpper96, and phyHrpUwbStsVCounter.

[0009] The object of the invention is to develop a method for locating mobile devices in a UWB localization network, which has a simple constructive and precise location of mobile devices, especially in buildings.

[0010] This problem is solved with the features of the first patent claim.

[0011] Advantageous embodiments arise from the subclaims.

[0012] The method for locating mobile devices in a UWB localization network comprises a network divided into clusters, each cluster having a plurality of network nodes such that the network nodes form a meshed network. The network nodes arranged in a cluster communicate by means of synchronization messages, wherein the synchronization messages comprise an STS field and a data field and synchronize within a cluster in ultra wideband (UWB) by sending and receiving, wherein the position of the network nodes in the UWB localization network is known and the network nodes of a cluster generate a cluster position from the positions of the individual network nodes such that the cluster position is used as an input variable for all network nodes in the cluster to generate the STS field used in the synchronization message.

[0013] The STS field generates a coded signal pattern for time recording in the receiver. The data field transmits information between the transmitter and receiver.

[0014] In an advantageous embodiment, in a first step, in particular, a rough positioning of the mobile device is carried out by the accessibility of network nodes located in a cluster and the reception of sent synchronization messages and the evaluation of the known position data of the network nodes contained in the synchronization message.

[0015] In a particularly advantageous embodiment, the mobile device and the network nodes connected in a cluster are operated with the same STS parameters, with precise positioning being achieved by detecting and evaluating time information from spatially nearby network nodes. Time measurement between the mobile device and the network nodes is performed via the STS field. This can be done, in particular, after coarse positioning.

[0016] Particularly preferably, the mobile device derives STS parameters from the rough position and the position data contained therein for STS generation. Furthermore, additional parameters, such as key information, can be included in the STS generation.

[0017] In an advantageous embodiment, in addition to the position data, time information is also used as a parameter in the STS generation. This embodiment generates a spatially / temporally variable STS.

[0018] Time measurement between the devices is thus carried out via the STS field. The network nodes serve as reference stations for the cluster.

[0019] In an advantageous embodiment, the synchronization message can contain, in addition to the STS field and data field, a SYNC field for temporally initializing the receiver. The order of the STS field and the data field can vary within the synchronization message.

[0020] In an advantageous embodiment, different clusters use different STS sequences. This allows for load minimization, since there is no detection or handling of time-error-prone timestamps caused by messages from neighboring clusters.

[0021] The cluster position is preferably generated by averaging the positions of the associated network nodes of a cluster and used as an input variable for STS generation. A mean value is used, whereby the arithmetic mean of all node positions in the cluster is calculated. Alternatively, the cluster position can be calculated by calculating a median value, which involves sorting the positions of all network nodes and then adopting the median position of the cluster. Another possibility is to use cluster boundaries to generate the STS; however, other calculations of the cluster position are also conceivable, whereby the cluster position is generally determined as a derived position measure of the network nodes' positions. The cluster position can be understood as a feature of the STS generation derived from the network nodes' positions.

[0022] The STS generation is preferably carried out according to the IEEE 802.15.4z standard, whereby the cluster position is included as a configuration parameter in a 96-bit input data field, in particular in the 96-bit input data field phyHrpUwbStsVUpper96 in the STS generation.

[0023] To locate themselves within the UWB localization network, mobile devices require knowledge of the STS parameters of the respective cluster.

[0024] In an advantageous embodiment, a cluster is delimited by walls in an indoor environment, forming a spatially coherent synchronization cluster. This ensures good radio propagation conditions and thus high synchronization quality within the clusters.

[0025] Advantageously, the synchronization message is encrypted.

[0026] The invention is explained in more detail below using an embodiment and associated drawings.

[0027] They show: Fig. 1 a schematic representation of a UWB localization network, Fig. 2 individual clusters with a spatial separation.

[0028] In Fig. Figure 1 shows a UWB localization network, wherein the UWB localization network is formed from several clusters C, in particular four clusters C1-C4, with network nodes N, in particular N1-N4, arranged therein. The network nodes N are interconnected within the respective cluster C, forming a meshed network. The network nodes N1-N4 are synchronized by sending and receiving synchronization messages, wherein the positions of the network nodes within the UWB localization network are known. The network nodes therefore serve as reference stations for the rough location of a mobile device.

[0029] The synchronization messages comprise a SYNC field, an STS field, and a DATA field. A cluster position is generated from the positions of the individual network nodes N1 - N4, which is used as an input for generating the STS field used in the synchronization message. The cluster position is preferably the averaged cluster position in the UWB localization network.

[0030] In the first cluster C1, a mobile device M, for example a smartphone or similar, is located and, in a first step, roughly locates itself in the cluster C1 by detecting the reachable surrounding network nodes N1. According to Fig. 1 four network nodes N1 are reached (shown in dashed lines).

[0031] By receiving the synchronization messages sent by the network node N1 and evaluating the known position data of the network node N1 contained in the synchronization message, the rough position is located by the mobile device M. The rough location can be carried out with the proportional accessibility of network node N1 by the mobile device M. The connection of the mobile device M with the accessible network node N1 is according to Fig. 1 is shown in dashed lines. Since the mobile device M and the network nodes N1 connected in a cluster must be operated with the same STS parameters, the STS parameters for STS generation in the mobile device M are derived from the known position data of all network nodes N1 of the cluster C1.

[0032] In the next step, after the rough positioning of the mobile device M, this data is used to determine the exact location in the UWB localization network. This is done by collecting and evaluating time information from the spatially nearby network nodes N1 (shown in dashed lines), with the time measurement between the mobile device and the network nodes being performed via the STS field.

[0033] In Fig. Figure 2 shows a UWB network with spatially separated clusters C1 - C4. The individual clusters C1 - C4 are delimited by walls W, which ensure good radio propagation conditions and thus high synchronization quality within the clusters C1 - C4. Synchronization messages are sent and received between the individual network nodes N1 - N4 for synchronization within the respective cluster. The individual clusters C1 - C4 have different STS sequences. This enables load minimization, since no detection / handling of time-errored timestamps by messages from neighboring clusters occurs. For example, in cluster C1, handling of synchronization messages from cluster C2 or C4 can be avoided.

[0034] The synchronization and positioning are shown schematically in the Fig.3. A network node N is configured as a transmitter. The sending network node transmits its own known position in the synchronization message, along with a transmission time in the data field. The receiver is either another network node N or a mobile device M.

[0035] In the case of a network node N acting as the receiver, the known position (dashed line) is used for synchronization. In the case of a mobile device, this locates itself in the network based on the time of receipt of the components of the STS field of the synchronization message and the data in the data field. Time measurement for the time of receipt is possible if the network node N acting as the sender and the network node N acting as the receiver, or the mobile device M acting as the receiver, are operated with the same STS parameters. These STS parameters are passed to an STS generator in the transmitter and to an STS correlator in the receiver. Time measurement is therefore performed via the STS field.

[0036] The STS generation scheme follows IEEE 802.15.4z, with the cluster position being incorporated into the STS generation as a configuration parameter in the 96-bit input data field phyHrpUwbStsVUpper96. The STS generation scheme is applied to both the transmitter's STS generator and the receiver's STS correlator. List of reference symbols C Cluster C1 first cluster C2 second cluster C3 third cluster C4 fourth cluster M mobile device N network nodes N1 network nodes of the first cluster N2 network nodes of the second cluster N3 network nodes of the third cluster N4 network nodes of the fourth cluster

Claims

[1] Method for locating mobile devices in an Ultra Wideband, UWB localization network, wherein the network is divided into clusters (C) and each cluster (C) has several network nodes (N) such that the network nodes (N) form a meshed network, characterized by , that - the network nodes (N) arranged in a cluster (C) synchronise themselves by sending and receiving synchronisation messages with a scrambled timestamp sequence, STS field and a data field within a cluster (C) in Ultra Wideband (UWB) and that - the position of the network nodes (N) in the UWB localization network is known and the network nodes (N) of a cluster (C) generate a cluster position from the positions of the individual network nodes (N) such that - the cluster position for all network nodes (N) of the cluster (C) is used as input to generate the STS field used in the synchronization message. [2] Method according to claim 1, characterized by that a rough positioning of the mobile device (M) is carried out by the accessibility of network nodes (N) located in a cluster (C) and the reception of sent synchronization messages and the evaluation of the known position data of the network nodes (N) contained in the synchronization message. [3] Method according to claim 1 or 2, characterized by that the mobile device and the network nodes (N) networked in a cluster (C) are operated with the same STS parameters and the exact positioning is carried out by recording and evaluating time information from spatially nearby network nodes (N), whereby the time measurement between the mobile device (M) and the network nodes (N) is carried out via the STS field. [4] Method according to claim 2 and 3, characterized by that the mobile device derives STS parameters from the coarse position and the position data contained therein for STS generation. [5] Method according to claim 4, characterized by that key information is included in the STS generation. [6] Method according to claim 4, characterized by that time information is included as a parameter in the STS generation. [7] Method according to one of claims 1 to 6, characterized by that the synchronization message contains a SYNC field for the temporal initialization of the receiver. [8] Method according to one of claims 1 to 7, characterized by that the order of the STS field and the data field may vary within the synchronization message. [9] Method according to one of claims 1 to 8, characterized by that different clusters (C) use different STS sequences. [10] Method according to one of claims 1 to 9, characterized by that a cluster position is formed by averaging the positions of the network nodes (N) of a cluster (C). [11] Method according to one of claims 1 to 10, characterized by that a cluster (C) is bounded by walls in such a way that a spatially coherent synchronization cluster is formed. [12] Method according to one of claims 1 to 11, characterized by that the synchronization message is encrypted.

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