Method for determining virtual topology of wireless bridge of communication system and communication system

Abstract

The present invention relates to a method for determining a topology of a time-sensitive network model of a wireless bridge handling a set of user equipments (UEs). Groups of user equipments are determined, wherein each group is formed by UEs with contention access to time resources. Different groups of UEs are independent in performance when enabled at the same time. And constructing a topology of the main block and providing the topology to a centralized network configuration node. The topology comprises: N network side ports, the network ports being associated with user equipment of a corresponding group; p device side ports, wherein the device side ports are associated with corresponding user equipment; and P internal links connecting the device-side ports of the user equipments associated to a given group with the network-side ports associated to the given group. The invention also relates to a corresponding communication system and a corresponding computer program.

Description

Technical Field

[0001] The present disclosure relates to the field of telecommunications. Background Art

[0002] More specifically, the present disclosure relates to a method for determining the topology of a time sensitive network model of a wireless bridge of a communication system within a time sensitive network. The present disclosure also relates to a corresponding communication system and a corresponding computer program.

[0003] The present disclosure addresses the problem of using 5G networks as a means of communication for Time Sensitive Networking (TSN), which was originally developed to provide communications with guaranteed time delivery over Ethernet wired networks for industrial applications.

[0004] As is customary in current TSN standards, when a flow passes through a TSN bridge, the end-to-end delay is calculated by taking into account the aggregate delay of the transmission links between the previous bridge on the path (external links) and the internal links of the bridge between the input (ingress) and output (egress) ports. In a typical TSN network, these aggregate delays are taken into account in the central scheduler or central network configuration node (CNC), which ensures that no packet collisions occur on the transmission links in the time domain.

[0005] In the context of a one-to-many bridge, the bottleneck is the external transmission link to which a TDMA (Time Division Multiple Access) strategy is applied due to CNC scheduling. Even though the internal links of the bridge can be used simultaneously, they are actually used sequentially due to TDMA on the input transmission links. When the capacity of the internal links is much higher than the capacity of the transmission links, the impact on performance is small. However, when the internal link capacity is comparable to or worse than the external link capacity, the convention of considering the aggregation delay causes a significant performance degradation. In fact, the bridge capacity is limited by not taking advantage of the possibility of using the internal links simultaneously.

[0006] This occurs when considering 5G TSN bridges, where the internal link capacity is related to the wireless transmission capacity, which is typically worse than the input link capacity that relies on wired Ethernet. By using the latest model and representing the 5GS as a one-to-many topology, a TDMA strategy is applied between all packets flowing through the 5G TSN bridge. Unfortunately, TDMA is often not the optimal multiplexing scheme for wireless networks, as improved performance can exploit other multiplexing dimensions. Examples of multiplexing dimensions include frequency (using multiple sub-bands in the frequency domain), space (using multiple antennas), and site (frequency reuse between multiple non-interfering sites). Therefore, the latest definition of the model of the 5G TSN bridge fails to exploit the multiplexing capabilities of the 5GS, which leads to suboptimal performance.

[0007] The time multiplexing capabilities of 5GS are often much lower than those of Ethernet fixed networks. For example, the smallest time unit of 5GS is the time slot, which is at least 100 microseconds long, while the maximum frame duration on a Gigabit Ethernet link is around 12 microseconds. Therefore, as a price for any frame transmission, the low time granularity of 5GS is taken into account in the declaration of independent delay. This is necessary because the guaranteed delay is calculated using dependent delay and independent delay in CNC. However, 5GS relies on a wireless interface, which naturally allows broadcasting. This involves multiple data streams that can be sent simultaneously with variable capacity depending on the deployment, terminal location and channel conditions, the number of data streams that share the wireless channel at the same time, etc. This multiplexing capability of 5GS is not inherently taken into account when considering the latest 5GS TSN bridge representation. In fact, for this bridge model, the CNC presents packets at the bridge input in a TDMA manner following the low internal time granularity of 5GS.

[0008] In order to improve system performance and utilize the multiplexing capability of wireless bridges such as 5GS and compensate for their low time granularity, a better TSN bridge model for designing such wireless bridges is needed. Summary of the invention

[0009] The present disclosure improves this situation.

[0010] A method for determining a virtual topology of a wireless bridge of a communication system within a time-sensitive network, the wireless bridge handling a set of P user equipments (UEs), the communication system also comprising a centralized network configuration node,

[0011] The method comprises the following steps:

[0012] -Build a virtual topology of a wireless bridge, the virtual topology includes at least a main block, the main block includes:

[0013] ○ N network-side ports, the network ports being associated with corresponding groups of user equipments with non-independent quality of experience handled by the wireless bridge,

[0014] ○ P device-side ports, the device-side ports are associated with corresponding user equipment, and

[0015] o N independent channels connecting device-side ports of user equipment associated with a given group with network-side ports associated with the given group, and

[0016] - Provide the virtual topology of the wireless bridge to the central network configuration node.

[0017] The main block represents the UE deployment as separate groups. N and P are natural numbers, where N is at least equal to 2, and each group includes at least one user equipment.

[0018] Non-independent quality of experience involves contention access to a set of physical channels that a wireless bridge uses as resources for processing a set of UEs. UEs with contention access to the set of physical channels are grouped together. In contrast, UEs with non-contention access to the set of physical channels are individually considered to be part of different groups. For example, UEs with contention access to time resources due to lack of orthogonalization in other dimensions (e.g., no space or frequency) multiplexing may be aggregated in the same group, while UEs without contention access to time resources may belong to different groups.

[0019] The virtual topology of the wireless bridge illustrates the reason for this particular division of the UE set into groups, as UEs of a given group are considered together for access through a common network side port, while UEs of different groups are represented as accessed through separate data paths involving different network side ports.

[0020] In this regard, providing a virtual topology of a wireless bridge to the CNC allows the multiplexing capabilities of the wireless bridge to be utilized.

[0021] In particular, providing a topology of master blocks allows data packets to be interpreted by the CNC as possibly arriving at different network-side ports at the same time. The result is that data transmission in 5GS does not need to systematically follow the TDMA method.

[0022] Providing the topology of the master block to the CNC is equivalent to providing the CNC with knowledge about the multiplexing capabilities of the wireless bridge in dimensions other than the time dimension. Providing the virtual topology of the wireless bridge model may include providing, for each independent channel, a pair of guaranteed delays associated to the channel, including a dependent delay and an independent delay both set to non-zero values.

[0023] Then, by determining the TSN schedule involving different groups of simultaneously enabled UEs, the CNC is able to better utilize the multiplexing capabilities of the wireless bridge and reduce the end-to-end latency without incurring performance loss.

[0024] The above method is understood to be implemented by computer means. In this regard, different functional entities can be defined. For example, the partitioning of the set of P user devices as described above is performed by one or more processors executing one or more incoming instructions. Therefore, the partitioning can be conceptually viewed as a task affected by a computing entity called a "partitioning module" or a "grouping module". Similarly, building a topology is a task affected by a computing entity called a "topology building module". Of course, the partitioning module and the topology building module can be indiscriminately hosted by the same physical entity such as a processor or by different physical entities. Providing a topology is a task affected by a computing entity called a "topology providing module" that controls a communication interface.

[0025] In another aspect, a computer software or program comprising one or more instructions is provided, which, when executed by a processor, implements at least a portion of the method defined herein. In another aspect, a computer-readable non-transitory recording medium having software registered thereon is provided, which, when executed by a processor, implements the method defined herein.

[0026] In another aspect, a communication system in a time-sensitive network is provided, the communication system comprising a wireless bridge for handling a set of P user equipments (UEs), the communication system further comprising a centralized network configuration node,

[0027] The communication system is configured to:

[0028] -Build a virtual topology of a wireless bridge, the virtual topology includes at least a main block, the main block includes:

[0029] ○ N network side ports, the network side ports being associated with corresponding groups of user equipments with non-independent quality of experience handled by the wireless bridge,

[0030] ○ P device-side ports, the device-side ports are associated with corresponding user equipment, and

[0031] o N independent channels, the independent channels connecting the device-side ports of the user equipment associated with the given group with the network-side ports associated with the given group, and

[0032] - Provide the virtual topology of the wireless bridge model to the central network configuration node.

[0033] The following features may optionally be implemented alone or in combination with each other.

[0034] The wireless bridge includes n physical network side ports, and the virtual topology may also include a demultiplexing block, which includes:

[0035] -n network side ports,

[0036] -N device-side ports, and

[0037] -N internal links, which connect the device-side ports with the network-side ports,

[0038] -The device-side ports of the demultiplexing block are associated with the corresponding network-side ports of the master block.

[0039] The main purpose of the demultiplexing block is to allow the virtual topology to be interpreted as having a single common network side port for all data flows looping through the wireless bridge.

[0040] Providing a virtual topology of the wireless bridge model then comprises providing, for each internal link of the demultiplexing block, a pair of guaranteed delays associated to said internal link, comprising a dependent delay and an independent delay. Both delays may advantageously be set to zero.

[0041] The groups may be formed within the set of P user equipments according to a predetermined criterion. The predetermined criterion may be related to the access of the set of user equipments to the set of physical channels used by the wireless bridge to handle the set of user equipments.

[0042] In fact, the partitioning results may vary according to various possible deployments of the user equipment sets and various deployments of base stations, and in particular, according to the multiplexing capabilities of the wireless bridges for each of these deployments.

[0043] The groups can be formed such that

[0044] - the user equipment is enabled when involved in the transmission of at least one data stream through the wireless bridge, and

[0045] - a data stream performance is related to a given data stream of at least one data stream,

[0046] - for user equipment belonging to any first subset of the same group of user equipment, the simultaneous activation of any user equipment in the first subset reduces data flow performance of at least one given user equipment in the first subset selected from among the user equipments simultaneously activated in the first subset, relative to a given user equipment in the first subset being activated individually, and

[0047] -For all user devices of any second subset belonging to different groups, the simultaneous activation of any user device in the second subset does not degrade the data flow performance of any given user device in the second subset selected among the user devices simultaneously activated in the second subset relative to the given user device in the second subset being activated individually.

[0048] When the difference in data flow performance between the simultaneous enabled case and the single enabled case exceeds a predetermined threshold (which may be an absolute threshold or a relative threshold), the data flow performance is said to be "degraded".

[0049] In the above example, any number of user equipments within the same group of user equipments have contention access to the time resources, while any number of user equipments each taken from a different group of user equipments do not have contention access to the time resources.

[0050] The groups may be formed further based on an indication regarding multiplexing capabilities at one or more base stations for deployment of the user equipment.

[0051] As further shown, the indications related to multiplexing capability may be of various natures and sources.For example, the indications related to multiplexing capability may include RAN level information and / or measurements of end-to-end QoS KPIs at the application layer of various enabled topologies.

[0052] In an example, the wireless bridge may include multiple base stations that each handle at least one corresponding user device, and groups may be formed based on an indication of which base station handles each user device such that any user devices belonging to the same group are handled by the same base station.

[0053] Even if handled by the same base station, user equipment may belong to different groups.

[0054] For example, a wireless bridge may include a given base station that processes a subset of a set of P user devices by orthogonalizing the transmissions of the user devices in the subset in a multi-antenna spatial dimension. Groups may then be formed based on an indication of the antennas used by the given base station to process the individual user devices in the subset, such that any user devices in the subset that belong to the same group are processed by the same antenna of the given base station.

[0055] In the above examples, the indication related to the multiplexing capability is RAN level information related to spatial and frequency multiplexing.

[0056] The wireless bridge may also include a given base station that handles the given two user devices by orthogonalizing transmissions with the given two user devices via a semi-static resource allocation scheme. Groups may then be formed based on an indication of the allocation scheme such that the two given user devices are affected by different groups.

[0057] This example shows a way to exploit the time-frequency multiplexing capability of a wireless bridge.

[0058] The multiplexing capability of a wireless bridge may be asymmetric, meaning that the uplink and downlink exhibit different performance.

[0059] In this regard, dependent quality of experience may be applied to all data transmissions having the same orientation as follows:

[0060] - Downlink, defined as the data transmission established from the wireless bridge to the individual user devices, and

[0061] - Uplink, defined as the data transmission established from each user equipment to the wireless bridge, such that the virtual topology is adapted to said orientation of the data transmission.

[0062] In other words, two separate virtual topologies of the same wireless bridge can be constructed, one optimized for uplink and the other for downlink. This possibility is made possible by the unidirectional nature of the delay provided to the CNC.

[0063] To this end, the method may further include constructing an additional virtual topology suitable for the wireless bridge in the opposite orientation, the additional virtual topology comprising at least a main block, the main block comprising:

[0064] - M network side ports, the network side ports being associated with a corresponding group of user equipments handled by the wireless bridge, and applying a dependent quality of experience to the opposite orientation,

[0065] - P device-side ports, the device-side ports being associated with corresponding user equipment, and

[0066] - M independent channels connecting device-side ports of user equipment associated to a given group with network-side ports associated to said given group, and

[0067] Additional virtual topologies of wireless bridges are provided to the central network configuration node.

[0068] M is a natural number, which may be equal to or different from N. For example, the virtual topology of the wireless bridge optimized for the downlink may include not only N independent channels associated with a finite delay, but also M additional independent channels (or M network-side ports) associated with an infinite delay. Similarly, the virtual topology of the wireless bridge optimized for the uplink may include not only M independent channels associated with a finite delay, but also N additional independent channels associated with an infinite delay. Then the two virtual topologies include the same number of N+M independent channels. Each of the channels corresponds to the same equivalent virtual port pair in the two virtual topologies, with only different delay values ​​advertised to the CNC. In another example, one network side port is associated with an independent downlink channel associated with a limited downlink delay and an independent uplink channel associated with a limited uplink delay; another network side port is associated only with an independent downlink channel associated with a limited downlink delay, and the delay corresponding to the uplink direction is set to infinite, and another network side port is associated only with an independent uplink channel associated with a limited uplink delay, and the downlink direction is associated with infinite delay.

[0069] Additional features, details, and advantages will be set forth in the following detailed description and in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] [ Figure 1 ] Figure 1 is an example of a TSN wireless bridge model according to an implementation scheme.

[0071] [ Figure 2 ] Figure 2 is an example of a TSN network according to an implementation.

[0072] [ Figure 3 ] Figure 3Delay calculation between two end stations through a TSN bridge according to an embodiment is shown.

[0073] [ Figure 4 ] Figure 4 Shown is gate opening and packet propagation along a data path according to an embodiment.

[0074] [ Figure 5 ] Figure 5 It is the latest manifestation of 5GS as a TSN bridge.

[0075] [ Figure 6 ] Figure 6 This is the latest representation of 5GS as a TSN bridge, which can be found in "Ericsson Technology Review, 5G-TSN integration meets networking requirements for industrial automation" (August 2019, Farkas, J.; Varga, B.; Miklós, G.; Sachs, J).

[0076] [ Figure 7 ] Figure 7 It is the latest manifestation of 5GS as a TSN bridge.

[0077] [ Figure 8 ] Figure 8 Shows spatial and frequency reuse between different node base stations of a wireless bridge according to an embodiment.

[0078] [ Fig. 9 ] Fig. 9 Spatial multiplexing using multiple antennas at a node base station of a wireless bridge according to an embodiment is shown.

[0079] [ Fig.10 ] Fig.10 Spatial multiplexing using multiple antennas at a node base station of a wireless bridge according to an embodiment is shown.

[0080] [ Fig.11 ] Fig.11 Time-frequency multiplexing by static scheduling or slicing at a node base station of a wireless bridge according to an embodiment is shown.

[0081] [ Fig.12 ] Fig.12 is an example of a TSN wireless bridge model according to an implementation scheme.

[0082] [ Fig.13 ] Fig.13 A deployment of a wireless communication system according to an embodiment is shown.

[0083] [ Fig.14 ] Fig.14 According to the implementation method Fig.13 Example of a TSN wireless bridge model for a wireless communication system.

[0084] [ Fig.15 ] Fig.15 is a flow chart of a software-implemented method for determining a topology suitable for a downlink of a TSN wireless bridge according to an embodiment.

[0085] [ Fig.16 ] Fig.16 is a flow chart of a software-implemented method for determining a topology suitable for an uplink of a TSN wireless bridge according to an embodiment.

[0086] [ Fig.17 ] Fig.17 is suitable for operation according to the embodiment Fig.15 and Fig.16 An example of a processing circuit for the software represented above. DETAILED DESCRIPTION

[0087] The present disclosure relates to clustering different user devices handled by a wireless bridge so that a given cluster regroups to enable user devices simultaneously which translates into a performance loss relative to enabling them sequentially. Any user device belongs to a single cluster. After such clustering, a master block (100) is then constructed.

[0088] The main block (100) includes as many network-side ports (10, 20) as the number of clusters and as many device-side ports (11, 12, 13, 21, 22) as the number of user devices handled by the wireless bridge. The main block also includes an internal link per device-side port. These internal links are Figure 1 Not shown separately.

[0089] Each cluster is associated with the corresponding network port (10, 20).

[0090] Each user device is associated with a corresponding device-side port (11, 12, 13, 21, 22).

[0091] For each given user device, a corresponding internal link with limited capacity connects a device-side port (12) associated with the device with a network-side port (10) associated with a cluster including the device.

[0092] Figure 1 An example of a virtual topology (1000) including such a master block (100) is provided in .

[0093] Each internal link has a iHere, “capacity” is used as a term to describe the ability of a wireless bridge to process data and is related to bandwidth. In TSN networks, capacity is converted between latency-dependent and latency-independent.

[0094] exist Figure 1 There are five internal links shown above:

[0095] - a first link between the first NW port and the first DS port, having a capacity denoted C'1,

[0096] - a second link between the first NW port and the second DS port, having a capacity denoted C'2,

[0097] - a third link between the first NW port and the third DS port, having a capacity denoted C'3,

[0098] - a fourth link between the second NW port and the fourth DS port, having a capacity denoted C'4, and

[0099] - A fifth link between the second NW port and the fifth DS port, having a capacity denoted C'5.

[0100] The main block (100) provides an accurate depiction of the performance at the wireless bridge when user devices belonging to different clusters are enabled simultaneously. Advertising such accurately depicted performance of the wireless bridge to a centralized network configuration (CNC) node of a time-sensitive network allows the CNC to improve the performance. Examples of these improvements involve increasing the number of supported TSN data streams and / or setting a reduced guaranteed latency for TSN data streams flowing through a 5GS bridge.

[0101] As an optional feature, Figure 1 Also shown is a demultiplexing block (200) having a single network-side port (210) and as many device-side ports (211, 212) as the number of network-side ports (10, 20) in the main block (100). For each device-side port (211, 212), the demultiplexing block (200) also includes an internal link with unlimited capacity connecting the device-side port to the network-side port (30).

[0102] The purpose of this demultiplexing block (200) is to allow the virtual topology (1000) of a wireless bridge to be interfaced with the model of another TSN bridge (300) in a simple manner.

[0103] This is related to the latest representation of intermediate TSN bridges that interface with each other using a single network-side port.

[0104] This particularity can be maintained by representing any wireless bridge in the TSN network by a combination of a main block (100) and a demultiplexing block (200), where the device-side ports (211, 212) of the demultiplexing block (200) are each connected to the corresponding network-side ports (10, 20) of the main block (100).

[0105] The resulting virtual topology (1000) can then interface with another TSN bridge (300) through the network-side port (210) of the demultiplexing block (200).

[0106] In the following, the present disclosure is described focusing on the downlink transmitted by the base station and received by the terminal. Of course, the present disclosure is also applicable to the uplink and the combination of the uplink and the downlink.

[0107] <TSN network>

[0108] The present disclosure focuses on the transmission of packets with latency constraints. In order to achieve an assured end-to-end delay for the packet transmission between the speaker and the listener, it is necessary to rely on a predetermined data path or the operation of network elements along that path for routing and scheduling.

[0109] According to the fully centralized model of IEEE 802.1Qcc, the TSN network includes multiple elements as Figure 2 shown.

[0110] Figure 2 The speaker (1) and the listener (2) are represented above, both as end stations (ES) of the TSN network. A series of TSN bridges (3) are also represented.

[0111] The TSN bridge (3) is a packet-switching device of the TSN network. Packets arriving at the entry port of the bridge can be routed to the exit port with a bounded latency according to some parameters specific to each port pair represented by the internal links. The parameters are typically: a latency-dependent factor (i.e., depending on the payload and can be regarded as the reciprocal of the instantaneous throughput of the link) and an independent latency (i.e., the fixed latency of each communication).

[0112] The TSN network also includes a centralized user configuration node (CUC) (4) configured to communicate with the end stations (1, 2) to receive their traffic requirements.

[0113] The TSN network also includes a centralized network configuration node (CNC) (5). The CNC is capable of receiving the exit and entry port identifications, traffic classes, and QoS indicators as the minimum latency and maximum latency for each port pair from different TSN bridges.

[0114] The CNC (5) can also receive data related to user configuration from the CUC (4) and from the TSN bridge (3) via the user / network interface. The data related to user configuration may include the traffic requirements of the end stations. The data related to user configuration may also include the TSN network topology related to the traffic requirements of the end stations. The data related to user configuration may also include the capacity of the network links according to the topology.

[0115] The CNC (5), which has collected the topology and capacity of the network links and the data flow requirements as described above, defines a routing decision, i.e., bridge selection, in other words, the data path for sending packets from one end station (1) to another end station (2) via the bridge (3). This data path is calculated by the CNC in a known manner to meet the flow requirements of the TSN flow.

[0116] The CNC (5) also calculates the gate opening schedule for packets flowing from one ES to another while ensuring its transmission delay, with the invariant purpose of meeting the flow requirements of the TSN flow. To this end, the CNC calculates the cumulative delay from the exit port to the exit port of two consecutive bridges on the calculated data path, where the exit port is defined at the output port of the bridge in the direction of packet flow along the path (while the entry port is the bridge input port).

[0117] The schedule calculated at the CNC is a time gating window table, and the gates open and close sequentially according to this table. In practice, for each bridge port, the packets are buffered and sent sequentially when the corresponding gate opens. Therefore, time multiplexing is inherent in each bridge port, and simultaneous transmission can be performed between two different ports of the TSN bridge.

[0118] <TSN Bridge Model Description>

[0119] Figure 3 Shows the definition of dependent delay and independent delay from the exit port of a bridge to the exit port of another bridge on the data path associated with a given data flow.

[0120] Three bridges (3) are represented on the data path, denoted as Bn-1, Bn, and Bn+1.

[0121] More specifically, for a given bridge Bn, the entry port (denoted as i) and the exit port (denoted as e) are represented on the data path and form an oriented port pair.

[0122] For each oriented port pair, the dependent delay provided by the bridge Bn is the sum of the following:

[0123] - The delay corresponding to the cable bandwidth between the exit port of the previous bridge Bn-1 and the entry port of Bn on the data path (denoted as D c ), and

[0124] -The delay corresponding to the internal bandwidth in Bn (denoted as ).

[0125] For each directional port pair, the independent delay provided by bridge Bn (denoted as ) corresponds to an internal mechanism in Bn that is independent of the packet length.

[0126] In addition, for each egress port of Bn, the propagation delay (denoted as TxPropagationDelay) can be defined as the transmission delay between the egress port on the data path in the cable and the ingress port of Bn+1.

[0127] Different flows may follow different data paths, each of which includes different directional port pairs within bridge Bn. The dependent delay and independent delay provided by bridge Bn may differ for each directional port pair, and the downstream propagation delay TxPropagationDelay may also differ for each egress port.

[0128] Figure 4 The opening time of the bridge gate defined by the CNC is shown to allow a packet of packet size P to propagate along the data path.

[0129] Figure 4 Three consecutive time intervals (6, 7, 8) are shown above.

[0130] The first time interval (6) corresponds to the opening of the bridge gate at bridge Bn-1. During this time interval, bridge Bn-1 is allowed to send packets through its egress port on the data path. The length of this time interval is calculated from the dependent delay provided by bridge Bn for the directional port pair on the data path and the packet size P.

[0131] The second time interval (7) begins at the end of the first time interval (6) and has a time length corresponding to the sum of:

[0132] - the propagation delay associated to the egress port of Bn-1 on the data path, and

[0133] - Independent delays provided by bridge Bn for directional port pairs on the data path.

[0134] Assuming that bridge Bn-1 has successfully sent the packet during the first time interval, the packet is guaranteed to be available at the egress port of bridge Bn at the end of the second time interval.

[0135] The third time interval (8) starts at the end of the second time interval (7) and corresponds to the opening of the bridge gate at bridge Bn. During this time interval, bridge Bn is allowed to send packets through its egress port on the data path. The length of this time interval is calculated from the dependent delay provided by bridge Bn+1 for the directional port pair on the data path and the packet size P.

[0136] As previously described, the end-to-end delay between two end stations is calculated by considering the aggregate delay of the transmission link between the previous bridge on the path (external link) and the internal link of the bridge between the input (ingress) and output (egress) ports. This is described in the 802.1Qcc standard as: "The length-dependent delay typically includes the time to receive and store each octet of the frame, which depends on the link speed of the ingress port. For example, if the ingress port operates at 1 Gb / s, both dependentDelayMin and dependentDelayMaxcan return 8000. If there is an internal communication mechanism within the architecture of the bridge (i.e., in a relay), the time of the mechanism is added to the frame-dependent delay. For example, if a 100 Mb / s serial link connects the ingress and egress ports, the previous example of a 1 Gb / s link speed may return 88000 for both dependentDelayMin and dependentDelayMaxcan" (the dependent delay is expressed in picoseconds according to the 802.1Qcc standard).

[0137] <5GS TSN bridge model description>

[0138] In the latest approach to integrating 5G Systems (5GS) in TSN networks, 5GS is represented as a conventional TSN bridge, which usually has Figure 5 A one-to-many topology of ports / gates is shown, where the bridge has one NW (network side) port (10) and two DS (device side) ports (11, 12). The internal structure of the 5GS bridge involves: a network side translator (NW-TT), which is a 5GS element that forms an interface between the TSN network and the 5G user plane (UP) on the 5G core network side; and a device side translator (DS-TT), which forms an interface between the 5G UP and the wireless device on the access network side. Optionally, multiple ports can be associated with one network side translator.

[0139] Figure 6 A more complete view of the internal structure of 5GS is given in Figure 1. The main components of 5GC (5G Core Network) and 5G RAN (5G Radio Access Network) are represented in the form of nodes or functional entities.

[0140] In particular, a functional split is observed between the control plane (50) and the user plane (60).

[0141] The control plane involves PCF (Policy Charging Function) and TSN-AF (Time Sensitive Network Application Function), both of which are nodes of 5GC (51).

[0142] The user plane involves the UPF (User Plane Function) for routing packets between the 5G-RAN and the network (NW) port. The user plane also involves the 5G-RAN, more specifically, the gNB (next generation node base station) configured to communicate with the UPF and handle the UE (user equipment).

[0143] In the user plane, a virtual TSN bridge can be considered. Considering a given data path, the virtual TSN bridge is defined with an NW port and multiple DS ports, where:

[0144] -NW ports are handled by UPF, and

[0145] - Each DS port is connected to the corresponding UE handled by the gNB.

[0146] The figure also shows the control elements of the TSN network in the form of CUC (4) (Centralized User Configuration Node) and CNC (5) (Centralized Network Configuration Node), which are connected to the 5GS control plane via TSN-AF.

[0147] On the control plane, the TSN application function (TSN-AF) calculates the capacity parameters of the internal links of the 5GS bridge.

[0148] When considering an end station (1) connected to the NW port of a virtual TSN bridge and multiple end stations (2) connected to DS ports associated with UEs of 5GS, it is natural to consider that each DS port and DS-TT is associated with each UE, as shown in the latest Figure 6 As shown in Figure 6 Two 5GS bridges are shown, each of which is defined on the network side by a NW-TT and a UPF.

[0149] Then, the dependent delay and independent delay of the port pair associated to the virtual TSN bridge are related to the UE radio link capacity in 5GS, as Figure 7 shown.

[0150] Figure 7 = represents two consecutive TSN bridges on a data path. Consider the downlink as an example.

[0151] The representation ( 300 ) of the upstream TSN bridge B0 ( 300 ) shows an ingress port ( 310 ) and an egress port ( 320 ).

[0152] One of the egress ports (320) in the representation (300) of the upstream TSN bridge B0 is connected to an ingress NW port (10) on the representation of the downstream virtual TSN bridge B (as a master block (100)). The representation of the virtual TSN bridge also includes at least two egress DS ports (11, 12). Each egress port (11, 12) is linked to the ingress port (10) via a corresponding internal link. The capacity of the internal links is denoted C1 and C2. In practice, the capacity of the internal links is related to the capacity of the radio link between the gNB and the UE.

[0153] Packets are sent through B's egress port (11, 12) via two internal links in a non-simultaneous manner according to B's ingress port (10) buffering received packets in time multiplexing and the CNC opening the gate of B0's egress port (310) so that packet collisions do not occur.

[0154] This results in TDMA (Time Division Multiple Access) transmission of packets within the 5GS, which is enforced by the packets arriving sequentially at the upstream egress port (310) of B0. Therefore, capacities C1 and C2 can be declared as capacities for individual UEs when enabled separately in the 5GS.

[0155] Unfortunately, TDMA is often not the best reuse scheme for wireless networks, as other reuse dimensions such as frequency (using multiple subbands in the frequency domain), space (using multiple antennas), and site (frequency reuse between multiple non-interfering sites) can be exploited without performance loss. Therefore, the latest definition of the 5G TSN bridge model does not fully exploit the reuse capabilities of 5GS, which leads to suboptimal performance.

[0156] <Determine the dependent group>

[0157] The reuse capabilities of wireless bridges such as 5GS bridges are identified in order to construct a virtual topology (1000) of wireless bridges suitable for CNC (5) to utilize wireless bridges under the 802.1Qcc standard.

[0158] Identifying the multiplexing capabilities of a wireless bridge other than time multiplexing corresponds to evaluating the possibility of performing simultaneous data transmission from and / or to different UEs in the time domain from a performance perspective. Simultaneous data transmission is the transmission of data from and / or to different UEs handled by one or more gNBs of the wireless bridge during overlapping times. In contrast, sequential data transmission is the continuous transmission of data (in time) from and / or to different UEs handled by one or more gNBs of the wireless bridge. In the following, a UE is referred to as "enabled" when it involves the transmission or reception of at least one data stream, and "not enabled" otherwise.

[0159] In other words, identifying the multiplexing capabilities of the wireless bridge other than time multiplexing corresponds to determining whether communication with a particular UE involves contention access to radio resources.

[0160] For example, the multiplexing capability of a wireless bridge can be determined from:

[0161] - known locations of base stations and UEs,

[0162] - known radio conditions between the base station and the UE,

[0163] - known base station scheduling configuration, and / or

[0164] - For a plurality of data streams sent through a wireless bridge, each data stream using a different data path, measurements relating to the performance of each of said data streams.

[0165] The UEs handled by the wireless bridge are then distributed into a plurality of groups based on the determined multiplexing capabilities of the wireless bridge.

[0166] Specifically, the UEs belong to the same group if their simultaneous activation reduces the performance of at least one data stream of at least one of the UEs relative to the data stream performance obtained when each of the UEs is activated separately and sequentially.

[0167] For any set of UEs that all belong to different groups, their simultaneous activation does not degrade any data flow performance relative to the data flow performance obtained when the UEs in the set are individually activated.

[0168] As already mentioned, the difference between the performance of at least one data flow under the simultaneous and sequential enabling conditions may be the result of data flow performance measurements rather than a direct result of the topology analysis of the wireless bridge. The difference between these measurements may be automatically compared to a predetermined absolute or relative non-zero threshold in order to unambiguously determine whether such difference corresponds to a degradation in performance.

[0169] We consider some examples of UE deployments where simultaneous transmission of packets does not degrade the performance of the data streams at the individual UEs, thus demonstrating multiplexing capabilities beyond time multiplexing.

[0170] Figure 8 The deployment of two UEs under two different gNBs (101, 102) is shown. The radio access network is usually designed so that no significant interference is observed in the downlink or uplink of neighboring gNBs. This can be achieved, for example, by using different frequency bands, controlling the power of gNBs and UEs, and / or using hybrid frequency / power control (known as inter-cell interference coordination).

[0171] As a result, data transmission from / to any UE handled by the first gNB (101) does not affect the performance of data transmission from / to any UE handled by the second gNB (102). This multiplexing capability is frequency and spatial multiplexing, as transmissions are isolated from each other due to the orthogonality in the spatial configuration and / or frequency band usage of the transmitter and receiver.

[0172] In this case, when distributing the UEs handled by the wireless bridge in a plurality of groups, based on the determined multiplexing capability of the wireless bridge, two groups of UEs may be formed, for example: one group formed by all UEs handled by the first gNB and the other group formed by all UEs handled by the second gNB. More generally, in this case, more than two groups of UEs may be formed if additional multiplexing capabilities of the wireless bridge are identified. However, none of the formed UE groups may include both UEs handled by the first gNB (101) and UEs handled by the second gNB (102).

[0173] Fig. 9 The deployment of two UEs within the coverage of the same gNB (101) is shown, where the gNB is equipped with multiple antennas and generates, for example, multiple beams (111, 112). Different multi-antenna technologies (e.g. Fig. 9 Beamforming (as represented in ) allows orthogonalizing the transmissions of multiple UEs in the multi-antenna spatial dimension. This involves two UEs using the same time-frequency resources without significant performance loss. Therefore, in this example, the two UEs can be distributed in two different UE groups.

[0174] In some cases, such as Fig.10 As shown, especially when the UEs are close to each other in space, the UEs cannot be orthogonalized by multi-antenna technology.

[0175] exist Fig.10 In Figure 1, three UEs are shown:

[0176] - a first UE connected to the first DS port (11) is handled by the gNB (101) using a first antenna generating a first beam (111),

[0177] - a second UE connected to the second DS port (12) is handled by the gNB (101) using the first antenna generating the first beam (111), and

[0178] -A third UE connected to the third DS port (21) is handled by the gNB (101) using a second antenna generating a second beam (112).

[0179] The first UE and the second UE are considered to be spatially close together so that the gNB can reach both of them using the same antenna.

[0180] Assuming that the first UE and the second UE are not orthogonalized, then according to the multi-antenna spatial orthogonality given by the multi-antenna technology used at the base station and the UE, following the definition of the group given above, a first group of UEs including the first UE and the second UE can be formed and a second group of UEs including the third UE can be formed.

[0181] exist Fig.11 In Figure 1, two UEs connected to different DS ports (11, 21) are under the coverage of the same gNB (101). One strategy of the gNB may be to semi-statically allocate a given share of radio resources to the active UE regardless of the state of its traffic (i.e. before knowing whether a packet is available for transmission). For example, semi-persistent scheduling may achieve this result in order to guarantee QoS for guaranteed bit rate (GBR) traffic. As a result, the performance of the individual UEs is independent regardless of their data traffic. In this case, following the definition of groups given above, the two UEs may be affected by different UE groups.

[0182] As shown in the above example, by analyzing the deployment and capabilities of transmission orthogonalization related to multiple UEs, the UEs can be grouped so that UEs belonging to the same group have contentious access to radio resources (i.e., they affect each other's performance when enabled simultaneously), while any UEs belonging to different groups are independent in terms of performance.

[0183] <Proposed TSN model for 5GS>

[0184] Now refer to Figure 1 .

[0185] Once the UE groups are formed and identified, a primary block (100) may be determined representing whether the different UEs have competing access to the radio resources or, on the contrary, whether their simultaneous activation does not affect the data flow performance.

[0186] The topology of the main block (100) is as follows.

[0187] The master block (100) includes as many NW ports (10, 20) as the number of identified UE groups. The master block (100) also includes as many DS ports (11, 12, 13, 21, 22) as the total number of UEs across all identified UE groups. The master block (100) also includes internal links between each NW port and all UEs belonging to the associated group.

[0188] Alternatively, the master block (100) may be determined as multiple model parts, one for each group of UEs, each model part having only one NW port and as many internal links and DS ports as the number of UEs in the associated group.

[0189] Any merged configuration of these model parts is possible as long as the configured link between the group-related NW ports and the UE-related DS ports is maintained.

[0190] The capacity on the internal link of the master block (100) can be learned by measurement, that is, data packets are sent to any UE and the capacity or latency is measured. As a remark, UEs of the same group should be learned independently, which involves that the capacity obtained for a given internal link is the capacity when the corresponding UE is the only one enabled in the UE group to which it belongs.

[0191] External links to any ingress port of the master block (100) may be assumed to have zero dependent delay and independent delay.

[0192] The number of physical NW ports that a 5G TSN bridge may have is not necessarily equal to the number of identified UE groups. In addition, the latest models of 5G TSN bridges often include a single NW port. Therefore, it is necessary to be able to define a model that conforms to the physical topology of a 5G wireless bridge from an external perspective.

[0193] In order to comply with the physical port topology, a demultiplexing (Demux) bridge model (200) may optionally be introduced, which has a number of NW ports (210) corresponding to the number of physical NW ports of the 5G TSN bridge and as many DS ports (211, 212) as the number of identified UE groups. The demultiplexing bridge also includes internal links to the NW ports per DS port. These internal links have zero independent delay and dependent delay (corresponding to infinite capacity). The external link has the characteristics of linking the 5GS CN to the physical interface of the TSN network (usually an Ethernet interface).

[0194] Fig.12 A simplified example of a virtual topology (1000) is provided in , which includes a demultiplexing block (200) with one NW port and a master block (100), where B' and B are the Demux and master bridges, respectively.

[0195] 5GS has two multiplexing degrees, each of which can support capacity C'i. Packets can arrive at B's ingress port (10, 20) simultaneously, i.e., packets can arrive at port (10, 20) separated by a time value that depends on B's ingress link bandwidth so that they are considered simultaneous to B with respect to its internal link capacity, which does not force TDMA transmission in 5GS.

[0196] As a result, the end-to-end delay of sending two identical packets from the upstream bridge B0 to the end station associated to the egress port (11, 21) of B is related to 1 / C'1+1 / C'2 when considering the latest model, while for the new model currently disclosed it is related to 1 / min(C'1, C'2). Therefore, the multiplexing capacity of 5GS is well utilized and the end-to-end delay is reduced.

[0197] <Example>

[0198] Fig.13 An example of a 5GS deployment is shown involving 2 gNBs (101, 102), 7 UEs and one ES per UE. Within each gNB, spatial multiplexing between groups of UEs is provided by beamforming techniques, for example relying on analog beamforming obtained with antenna arrays. Two radio frequency chains are available at each gNB and beams (111, 112, 121, 122) can be enabled simultaneously. For each gNB, the handled UEs are clustered in two groups (spatial separation), as defined above. UEs handled by different gNBs do not interfere with each other, either because the gNBs are separated far enough (spatial separation) or because the gNBs use different frequency channels (frequency separation).

[0199] Fig.14 An example of a corresponding virtual topology (1000) is provided in FIG. 1 , which has a master block (100) and a demultiplexing block (200).

[0200] The master block (100) has four ingress ports associated with the four aforementioned groups and seven egress ports associated with the seven aforementioned UEs.

[0201] The first ingress port is connected to a first UE and a second UE, which simultaneously share the same time / frequency resources under a first beam (111) of a first node base station (101).

[0202] The second ingress port is connected to a third UE, which is processed by the second beam (112) of the first node base station (101) and does not observe impact from other UEs.

[0203] The third ingress port is connected to a fourth UE, which is processed by the first beam (121) of the second node base station (102) and does not observe impact from other UEs.

[0204] The fourth ingress port is connected to a fifth UE, a sixth UE and a seventh UE, which simultaneously share the same time / frequency resources under the second beam (122) of the second node base station (102).

[0205] <Application to Uplink>

[0206] Although the above examples focus on the downlink, one of ordinary skill in the art can easily apply the same principles to the uplink, where the ingress port is a DS port and the egress port is a NW port.

[0207] Then two different models are constructed for downlink and uplink.

[0208] In practice, the uplink radio access technology may be different from the downlink radio access technology.

[0209] This may result in different ways of grouping UEs and different capacity measurements of the internal links of the bridge.

[0210] Considering the uplink specifically, the master block has as many ingress ports as the number of UEs handled by the gNB of the radio bridge and as many egress ports as the number of UE groups.

[0211] Optionally, the egress ports of the master block are each connected to an ingress port of a multiplexing (Mux) model, which has a number of egress ports corresponding to the physical number of NW ports of the 5GTSN bridge.

[0212] <Algorithm and processing circuit>

[0213] Fig.15 is a flow chart representing a general algorithm of a computer program that may be stored on a storage medium and / or may be carried as a signal, the purpose of which is to perform the method disclosed above for determining the topology of a time-sensitive network model of a wireless bridge of a communication system within a time-sensitive network for downlink applications.

[0214] The algorithm includes: forming N groups of user equipment among a set of P user equipments handled by a wireless bridge (S1). Both N and P are natural numbers greater than 1.

[0215] As already mentioned, user devices are enabled when they involve transmission of at least one data stream through a wireless bridge, and the data stream performance is related to a given data stream in the at least one data stream, and for user devices belonging to any first subset of the same group of user devices, the simultaneous enabling of more than one user device in the first subset reduces the data stream performance at the wireless bridge relative to enabling a single user device in the first subset, and for user devices belonging to any second subset of all different groups, the simultaneous enabling of all user devices in the second subset does not reduce the data stream performance at the wireless bridge relative to enabling a single user device in the second subset.

[0216] The algorithm then includes: constructing (S2) the topology of a time-sensitive network model of the wireless bridge, the time-sensitive network model including at least a main block, the main block including: N network-side ports, the network ports being associated with corresponding groups of user devices processed by the wireless bridge; P device-side ports, the device-side ports being associated with corresponding user devices; and P internal links, the internal links connecting the device-side ports of user devices associated with a given group with the network-side ports associated with the given group.

[0217] The algorithm finally comprises providing (S3) the topology of the time sensitive network model to a centralized network configuration node within the communication system.

[0218] Fig.16 is a flow chart representing a general algorithm of a computer program that may be stored on a storage medium and / or may be carried as a signal, the purpose of which is to perform the method disclosed above for determining the topology of a time-sensitive network model of a wireless bridge of a communication system within a time-sensitive network for uplink applications.

[0219] The algorithm includes: forming (S4) M groups of user equipment within a set of P user equipment, so that the uplink data flow performance is related to the uplink data flow defined as data transmission from each enabled user equipment to the wireless bridge, for any first subset of user equipment belonging to the same group of user equipment, relative to enabling a single user equipment in the first subset, the simultaneous enabling of all user equipment in the first subset reduces the uplink data flow performance at the wireless bridge, and for any second subset of user equipment all belonging to different groups, relative to enabling a single user equipment in the second subset, the simultaneous enabling of all user equipment in the second subset does not reduce the uplink data flow performance at the wireless bridge.

[0220] The algorithm then includes: constructing (S5) a topology of an uplink main block, the main block comprising: M network side ports, the network ports being associated with corresponding groups of user equipment processed by the wireless bridge; P device side ports, the device side ports being associated with corresponding user equipment; and P internal links, the internal links connecting the device side ports of user equipment associated with a given group with the network side ports associated with the given group.

[0221] The algorithm finally comprises providing a centralized network configuration node within the communication system with the topology of the uplink master block, or (more generally) providing (S6) the topology of a time sensitive network model of a wireless bridge comprising such an uplink master block.

[0222] Fig.17 A processing circuit (90) suitable for running any one or both of the above algorithms is schematically represented. The processing circuit comprises a memory (92) for storing a computer program comprising the algorithm. The processing circuit further comprises a processor (91) for accessing the memory and running the computer program. The processing circuit further comprises a communication interface (93) controllable by the processor for sending at least the topology of the time sensitive network model to a centralized network configuration node within the communication system.

[0223] Of course, it does not matter whether the processor (91) uses a single core or multiple cores to run the computer program. Cloud computing technology can also be used to run computer programs across processors of multiple processing circuits.

[0224] <Reference List>

[0225] The following non-patent elements are incorporated by reference for any purpose:

[0226] -nplcit1: IEEE 802.1Q-2018, see https: / / 1.ieee802.org / tsn / 802-1q / ;

[0227] -nplcit2: IEEE 802.1Qcc-2018, see https: / / 1.ieee802.org / tsn / 802-1qcc / ;

[0228] -nplcit3: 3GPP TR 23.734V16.2.0(2019-06), "Study on enhancement of 5GSystem(5GS) for vertical and Local Area Network(LAN)services";

[0229] -nplcit4: 3GPP TS23.501;

[0230] -nplcit5:Ana et al., Analysis of 5G-TSN Integration to Support Industry 4.0, Proceedings of the IEEE 25th International Conference on Emerging Technologies and Factory Automation (ETFA 2020); and

[0231] -nplcit6: Mannweiler et al., Reliable and Deterministic MobileCommunications for Industry 4.0: Key Challenges and Solutions for the Integration of the 3GPP 5G System with IEEE Time-Sensitive Networking, ITG-Fachbericht 288: Mobilkommunikation, 15-16.05.2019.

Claims

1. A method for determining a virtual topology of a wireless bridge of a communication system within a time-sensitive network, the wireless bridge processing a set of P user devices, the communication system further comprising a centralized network configuration node, The method comprises the following steps: - construct a virtual topology of the wireless bridge, the virtual topology comprising at least a main block, the main block comprising: o N network side ports, the network side ports being associated with corresponding groups of user equipments with non-independent quality of experience handled by the wireless bridge, ○ P device-side ports, the device-side ports are associated with corresponding user equipment, and o N independent channels, independent channels connecting the device-side ports of the user equipment associated with a given group with the network-side ports associated with the given group, and - providing said virtual topology of said wireless bridges to a central network configuration node.

2. The method according to claim 1, wherein: The wireless bridge includes n physical network side ports: - The virtual topology further comprises a demultiplexing block, the demultiplexing block comprising: ○n network side ports, ○N device-side ports, and ○N internal links, which connect the device-side port to the network-side port. -The device-side ports of the demultiplexing block are associated with corresponding network-side ports of the master block.

3. The method according to claim 1 or 2, wherein: Groups are formed within the set of P user equipment according to predetermined criteria related to access by the set of user equipment to the set of physical channels used by the wireless bridge to handle the set of user equipment.

4. The method according to claim 3, wherein: The group is formed further based on an indication regarding multiplexing capabilities at one or more base stations deployed for the user equipment.

5. The method according to claim 3 or 4, wherein: The groups are formed such that: o a user device is enabled in relation to transmission of at least one data stream through the wireless bridge, and o a data stream performance is associated with a given data stream of the at least one data stream, o for user equipment of any first subset of user equipment belonging to the same group, simultaneous activation of any user equipment in the first subset degrades the data flow performance of at least one given user equipment in the first subset selected among the simultaneously activated user equipment in the first subset relative to when a given user equipment in the first subset is enabled individually, and ○ For user devices of any second subset that all belong to different groups, the simultaneous activation of any user device in the second subset will not degrade the data flow performance of any given user device in the second subset selected among the simultaneously enabled user devices in the second subset relative to when a given user device in the second subset is enabled individually.

6. The method according to claim 4, wherein: - the wireless bridge comprises a plurality of base stations, each base station processes at least one corresponding user equipment, and - The groups are formed based on an indication of which base station handles each user equipment, such that any user equipment belonging to the same group is handled by the same base station.

7. The method according to claim 4, wherein: - the wireless bridge comprises a given base station for processing a subset of the set of P user equipments by orthogonalizing transmissions of the user equipments in the subset in a multi-antenna spatial dimension, and - forming the groups based on an indication of antennas used by the given base station to process individual user equipments in the subset such that any user equipments in the subset belonging to the same group are processed by the same antenna of the given base station.

8. The method according to claim 4, wherein: - the wireless bridge comprises a given base station for handling two given user equipments by orthogonalizing transmissions with the two given user equipments via a semi-static resource allocation scheme, and - forming said groups based on an indication of said allocation scheme such that said two given user equipments are affected by different groups.

9. The method according to any one of claims 1 to 8, wherein: The dependent quality of experience is applied to all data transmissions with the same orientation as follows: - Downlink, defined as the data transmission established from the wireless bridge to each user equipment, and - Uplink, defined as the data transmission from each user equipment to the wireless bridge, The virtual topology is adapted to the orientation of the data transmission.

10. The method according to claim 9, further comprising the steps of: - constructing an additional virtual topology adapted to said wireless bridge in the opposite orientation, said additional virtual topology comprising at least a main block, said main block comprising: o M network-side ports, the network-side ports being associated with a corresponding group of user equipments processed by the wireless bridge and having a dependent quality of experience applied to the opposite orientation, ○ P device-side ports, the device-side ports are associated with corresponding user equipment, and o M independent channels, independent channels connecting the device-side ports of the user equipment associated with a given group with the network-side ports associated with the given group, and - providing said additional virtual topology of said wireless bridge to said central network configuration node.

11. A communication system in a time-sensitive network, the communication system comprising a wireless bridge for processing a set of P user devices, the communication system further comprising a centralized network configuration node, The communication system is configured to: - construct a virtual topology of the wireless bridge, the virtual topology comprising at least a main block, the main block comprising: o N network side ports, the network side ports being associated with corresponding groups of user equipments with non-independent quality of experience handled by the wireless bridge, ○ P device-side ports, the device-side ports are associated with corresponding user equipment, and o N independent channels, independent channels connecting the device-side ports of the user equipment associated with a given group with the network-side ports associated with the given group, and - providing said virtual topology of the wireless bridge model to a central network configuration node.

12. A computer program comprising instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 10.

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