Method for scheduling TSN flows, communication system and central network configuration entity

Abstract

The present disclosure relates to a method for scheduling TSN flows in a communication system in a time sensitive network (TSN), the method being implemented in a central network configuration entity, where assistance information regarding a time granularity of transmission opportunities within a radio frame is obtained from at least one TSN bridge, and the TSN flows are scheduled by calculating time series of a number of TSN flows to the time granularity based on the obtained assistance information, the TSN flows being scheduled, the present disclosure further relates to a corresponding communication system and a corresponding central network configuration entity.

Description

[Technical field]

[0001] The present disclosure relates generally to a method and system for time-sensitive networking (TSN), and more particularly to a TSN network including wireless bridges, such as 5G systems (5GS).

[0002] In particular, a method for scheduling TSN flows, a communication system in which such a method is implemented, a central network configuration entity in such a communication system as an entity configured to implement such a method, a computer program for implementing such a method in the central network configuration entity, and a computer readable storage medium for storing such a computer program are disclosed. [Background technology]

[0003] Fast and reliable communication and information networking, especially Time Sensitive Networking (TSN), is essential for the smart factory environment. Such networking enables factory-wide integration by tightly connecting the individual production steps as well as production planning and logistics.

[0004] To provide the required connectivity, industrial networks need to support various types of traffic, including time-sensitive (TS) traffic used for real-time control of machines and services that require deterministic performance.

[0005] Time Sensitive Networking (TSN) is standardized by IEEE 802.1Q to provide industrial networks with deterministic delays for processing TS traffic. End-to-end communication deadlines and bounded jitter are guaranteed through multiple mechanisms such as time synchronization of individual frames and streams and TSN scheduling with respect to per-stream and per-port gate control lists generated for all components in the network, as standardized by IEEE 802.1Qcc for example.

[0006] Initially, TSN was targeted at wired networks capable of supporting high-speed communication between sensors / controllers and IT centers. Moving sensors and actuators from wired to wireless brings additional benefits such as mobility, scalability, and reduced maintenance costs. To connect wireless devices to a TSN network, wireless transmission technologies as defined by 3GPP™ are required.

[0007] The convergence of wired and wireless technologies raises several challenges that have yet to be fully resolved, such as standards compatibility and the nature of data transmission over (limited) wired and (open) wireless media.

[0008] As an Ethernet network, TSN is formed by end nodes (talker / listener nodes) and bridge nodes that connect the end nodes through bidirectional Ethernet links.

[0009] In a centralized architecture, end stations send flow requirements and TSN communication configurations to a centralized user configuration entity (CUC).

[0010] The CUC sends the user configuration to a centralized network configuration entity (CNC).

[0011] Each TSN switch identifies the CNC as a latency-managed object. The parameters sent by the switch to the TSN are egress and ingress port identification, traffic class, and QoS parameters such as minimum and maximum latency per port pair.

[0012] The CNC calculates the schedules, i.e., transmission times, of intermediate switches between TSN end stations, and the control parameters and routing decisions, i.e., switch selection, of the TAS of different switches, such that these calculations are made to meet the stream requirements of the TSN communication.

[0013] FIG. 1 shows the interaction between a 5G system and a CNC according to the 3GPP TS23.501 standard, and FIG. 2 shows a generic model of a 5G system acting as a wireless bridge.

[0014] Generally speaking, a wireless bridge is an entity of a TSN network whose function is to connect an upstream sub-network with a downstream sub-network through wireless means. In Fig. 1, the 5G system 11 is considered as a TSN bridge that receives timing and control information from a Central Network Configuration Entity (CNC) 12 through a TSN Application Function (AF) 13. The TSN-AF converts the control information from the CNC into policy controls that define a profile of a Packet Data Unit (PDU) session. This profile has the purpose of propagating TSN packets in the network, considered as a logical TSN bridge to TSN end stations, according to the CNC timing schedule.

[0015] 5G System 11 is - User Plane Function (UPF) 21, which represents a component of the 3GPP 5G core infrastructure system architecture; At least one base station (gNB) 22; at least one User Equipment (UE) 23; Equipped with.

[0016] At least one UE is wirelessly connected to at least one gNB and has at least one device-side (DS) port 24. Figure 2 illustrates K such DS ports, where K is any positive integer. The UPF has a wireline connection to at least one gNB and typically has at least one network-side (NW) port 25. Figure 2 illustrates N such NW ports, where N is any positive integer.

[0017] The 5GS bridge also includes a TSN Application Function (AF) 13 that enables communication with a Centralized Network Configuration (CNC) entity 12. The CNC 12 discovers the physical topology and TSN capabilities of the network infrastructure (e.g., links and bridges), calculates the TSN scheduling, and configures the TSN capabilities of the bridge according to the TSN scheduling, thereby enabling the desired connection of at least two ESs according to the stream request. In this respect, the CNC communicates with bridges in the network, as shown in FIG. 1, including communication with the 5GS bridge depicted in FIG. 2. In particular, the 5GS bridge receives timing and control information from the Central Network Configuration Entity (CNC) 12 through the TSN Application Function (AF) 13. The TSN-AF translates the control information from the CNC into policy controls that define the profile of the packet data unit (PDU) session. This profile has the purpose of propagating TSN packets in the network according to the CNC timing schedule, and is considered as a logical TSN bridge to the TSN end station.

[0018] Finally, each port can be equipped with a TSN translator (TT), the purpose of which is to hide the internal functioning of the 5GS bridge from the CNC and other network entities.

[0019] The TSN network may further comprise at least one wired TSN bridge having a fixed configuration in the sense that the TSN capability can be characterized by a single set of TSN parameters, e.g., minimum / maximum dependent delay and independent delay per port or per port pair, according to IEEE 802.1Qcc.

[0020] Unlike wired bridges, 5GS bridges feature variable TSN capabilities that can be adjusted on demand by adjusting the internal functions of the 5GS bridges with respect to wireless communication. In particular, this may relate to an independent delay, a dependent delay per port pair related to the throughput capacity of the corresponding wireless link, or both. The dependent delay per port pair may also be related to the amount of resources periodically reserved for transmission and the wireless link quality related to the transmission. The contention for the wireless resources used between UEs results in the interdependent nature of the wireless links, where the more resources are provided to a particular link, the less resources are left for other links. Such an agile 5GS bridge throughput capacity per UE makes it possible to adjust the 5GS bridge performance according to the traffic load and optimize its performance.

[0021] In wireless communications, transmissions are slotted. The wireless medium is divided in the time dimension into multiple elements called frames. The frames themselves are composed of slots. Slots are assigned to incoming data by a function called the scheduler, depending on various factors such as QoS requirements (usually delay, bandwidth, packet error rate), packet waiting time, and desired fairness. The start of a transmission begins at the start of a slot. Thus, whatever the scheduler's decision, the transmission opportunities (TxOps) are distinct and incoming packets must wait at least until the next TxOp before they can access the wireless medium.

[0022] For this reason, TxOps introduce jitter, which is usually included in the transmission delay that a system can tolerate. For time-sensitive traffic (TSC), this jitter can be absorbed by implementing a leaky bucket at the output, but at the expense of a delay corresponding to the maximum jitter.

[0023] In a TSN system, the CNC schedules the different flows in all network devices with the goal of having deterministic end-to-end transmission times. For this purpose, the CNC needs to have precise information about the delays introduced by the network devices along the data path. If the network device is a 5GS bridge, the TxOp granularity is included in the maximum delay that the 5GS bridge advertises. This is a conservative approach and leads to not utilizing the actual capabilities of the 5GS bridge.

[0024] There are two conventional ways to multiplex the two directions in a radio transmission. One is to separate the two directions in frequency (Frequency Division Duplex (FDD)), having a chunk of spectrum dedicated to one direction (e.g. uplink UL) and another chunk of spectrum dedicated to the other direction, downlink (DL). In FDD mode, UL and DL transmissions may occur simultaneously in time. Another possibility is to separate the two directions in time (Time Division Duplex (TDD)). In TDD mode, a slot in a frame is assigned to either UL or DL. Thus, UL and DL never occur simultaneously, which introduces an additional delay in the TxOp that is taken into account when calculating the transmission delay of the 5GS bridge.

[0025] In 5G systems, it is possible for the scheduler to preempt a slot already assigned to a data flow at the last moment to transmit a data element that is considered urgent and has just arrived, minimizing its transmission delay at the expense of retransmission of the preempted data flow. However, this mechanism is not well adapted to the TSN scenario for several reasons. This mechanism works well in DL, but is much less efficient in UL, because the scheduler in the base station must first acknowledge the arrival of the data element at the UE side. And TSN flows are usually periodic, and frequent and regular preemption leads to poor performance of the remaining traffic. If the majority of the traffic is TSC, there are few resources left to preempt. Another reason is that the key metric in a TSN environment is to have a deterministic (stable in time), bounded and controlled transmission delay. In the context of TSN, it seems better to have an allocation policy in the radio scheduler that is predictable.

[0026] The 5G TDD mode offers flexibility in terms of UL / DL splitting, allowing to dynamically adapt the radio resources in UL and DL depending on the traffic direction. However, this comes at the expense of interference generation. In fact, this is generally recommended and some spectrum regulations mandate that base stations operating in a given frequency band are fully synchronized in time and use a common UL / DL pattern. Assuming that for TSN there is flexibility in the 5GS Bridge to choose a given UL / DL pattern, the question is how to choose this to optimize performance for a given traffic, considering that the choice of UL / DL pattern has an impact on the 5GS Bridge delay performance. Summary of the Invention

[0027] The invention is defined by the appended independent claims. Further features and advantages of the concepts disclosed herein are set forth in the following description.

[0028] This disclosure aims to improve the situation.

[0029] To this end, the present disclosure provides a method for scheduling TSN flows in a communication system in a time sensitive network, the method being performed in a central network configuration entity, the method comprising: - obtaining assistance information regarding a time granularity of a transmission opportunity within a transmission frame from at least one TSN bridge having an internal time constraint; - scheduling the TSN flows by calculating time series of the multiple TSN flows to a time granularity based on the obtained assistance information; The present invention describes a method including:

[0030] According to the method, a TSN bridge provides assistance information regarding the time granularity of its transmission opportunities to a central network configuration entity (hereafter CNC), which takes this information into account when calculating the time series of flows of different TSNs.

[0031] For example, the aiding information enables the CNC to understand what the resulting transmission delay of the TSN bridge will be for a potential set of time series. As a result, the CNC can be configured to optimize the transmission delay of the TSN bridge by scheduling TSN flows according to specifically determined time series to collectively maximize the use of available transmission opportunities.

[0032] In one example, the aiding information from the TSN bridge includes a period and an offset, which is defined relative to a clock common to the central network configuration entity and the TSN bridge.

[0033] Such a combination of periods and offsets allows the CNC to know exactly the time frame of each slot within a frame, and as a result, the CNC can, for example, schedule the arrival of a packet towards the end of the slot and schedule the transmission of the packet just after the start of the next slot to minimize the transmission delay of that packet.

[0034] In one example, the aiding information from the TSN bridge includes a time period and, for multiple directional port pairs, further includes a corresponding offset, which is defined relative to a clock common to the central network configuration entity and the TSN bridge.

[0035] Providing distinct offsets for each directional port pair allows the CNC to use different rules for scheduling flows through a given port pair depending on the direction of the flow through that port pair, resulting in both uplink and downlink communications being optimized while being treated with different priorities.

[0036] In one example, the period corresponds to a slot duration and the offset indicates the start of the slot.

[0037] This allows the CNC to easily determine the start and end times of each slot from just a few values, by simple modulo arithmetic, resulting in a joint minimization of network resources for transmitting aiding information and computational resources at the CNC.

[0038] In one example, the period corresponds to a slot duration, and the first offset indicates the start of a first group of statically assigned transmission opportunities in a first transmission direction, and the second offset indicates the start of a second group of statically assigned transmission opportunities in a second transmission direction.

[0039] In such an example, for a frame structure containing two parts, each slot statically assigned to a corresponding transmission direction, the CNC can easily determine when to successfully and optimally schedule packet arrival times, and conversely, packet transmission times, based only on succinct assistance information limited to only three values.

[0040] In one example, the assistance information from the TSN bridge further includes an indication of an allocation of transmission opportunities in slots for the first transmission direction and the second transmission direction.

[0041] In this example, the aiding information is designed to be robust in that it enables the CNC to optimally schedule bidirectional transmissions regardless of the subdivision nature of the transmission opportunities within one or more slots of a frame.

[0042] In one example, the indication includes a corresponding bitmap of the availability status of each transmission opportunity within a slot for multiple directional port pairs.

[0043] A bitmap, in which each availability status is encoded into a single bit, is a simple and efficient way of informing the CNC whether each transmission opportunity is available or not for a given directional port pair.

[0044] As a result, the CNC can calculate, for each directional port pair, a time series in which flows are scheduled only on transmission opportunities available for this directional port pair. As a result, such calculated time series can respect the frame structure even if the CNC is not provided with details related to the frame structure in terms of whether uplink or downlink traffic is allowed for each transmission opportunity. Thus, packets can be efficiently transmitted and received at the TSN bridge at optimal times according to the schedule. As a result, delays through the TSN bridge are precisely managed.

[0045] In one example, the indication may be: - a plurality of bitmaps of availability status of each transmission opportunity within a slot for a given transmission direction, the bitmaps corresponding to a given possible slot structure; - a corresponding index into a particular bitmap among a plurality of bitmaps for a plurality of directional port pairs; Includes.

[0046] As a result, the overall amount of assistance information sent by the TSN bridge to the CNC is minimized compared to the former example, especially in scenarios where a small number of different frame structures are shared by multiple directional port pairs.

[0047] In one example, the assistance information from the TSN bridge may include: an indication of a corresponding nature of each transmission opportunity, each nature being flexible or fixed; the flexible property is associated with a flexible use with respect to the first transmission direction and the second transmission direction, an indication that the fixed nature is associated with a fixed use of only one transmission direction between the first transmission direction and the second transmission direction; - an indication of corresponding transmission directions between the first transmission direction and the second transmission direction for a plurality of directional port pairs; Further includes:

[0048] This allows optimization of transmission delays even when taking into account that some transmission opportunities are flexible, i.e. are not forcibly dedicated to either uplink or downlink transmission in the frame structure description in the TSN bridge, but in fact are assigned by the base station at the last moment to either uplink or downlink transmission.

[0049] The present disclosure provides, in another aspect, a method for producing a method of a method for producing a pharmaceutical composition comprising: - a communication system as above, - a central network configuration entity of said communication system; - a computer-readable storage medium comprising instructions that, when executed by a processing unit, cause the processing unit to perform a method as described herein; - a computer program accessible to a processing unit and comprising one or more stored sequences of instructions which, when executed by the processing unit, cause the processing unit to perform the methods described herein; and - a processing circuit configured to perform the methods described herein, comprising a processing unit operably connected to a memory; Also described below. [Brief description of the drawings]

[0050] [Figure 1] FIG. 1 illustrates a 5G system acting as a logical TSN bridge according to the 3GPP TS23.501 standard, as known from the prior art. [Diagram 2] FIG. 1 shows a generic model of a 5GS bridge known from the prior art. [Diagram 3] A diagram illustrating the difference between scheduling of TSN flows according to the prior art and scheduling of TSN flows according to an exemplary embodiment of the invention, in terms of transmission frames, where time alignment at the slot level is performed. [Figure 3a] A diagram illustrating the difference between scheduling of TSN flows according to the prior art and scheduling of TSN flows according to an exemplary embodiment of the invention, in terms of transmission frames, where time alignment at the slot level is performed. [Figure 3b] A diagram illustrating the difference between scheduling of TSN flows according to the prior art and scheduling of TSN flows according to an exemplary embodiment of the invention, in terms of transmission frames, where time alignment at the slot level is performed. [Figure 4]FIG. 2 illustrates the difference between scheduling of TSN flows according to the prior art and according to an exemplary embodiment of the invention for a transmission frame having a simple UL / DL TDD frame structure. [Figure 4a] FIG. 2 illustrates the difference between scheduling of TSN flows according to the prior art and according to an exemplary embodiment of the invention for a transmission frame having a simple UL / DL TDD frame structure. [Figure 4b] FIG. 2 illustrates the difference between scheduling of TSN flows according to the prior art and according to an exemplary embodiment of the invention for a transmission frame having a simple UL / DL TDD frame structure. [Diagram 5] A diagram illustrating the nature of the assistance information transmitted by a TSN bridge in the case of a transmission frame having a simple UL / DL TDD frame structure according to an exemplary embodiment of the present invention. [Figure 6] A diagram illustrating the nature of the assistance information transmitted by a TSN bridge in the case of a transmission frame having a flexible UL / DL TDD frame structure according to an exemplary embodiment of the present invention. [Figure 7] A diagram illustrating the nature of assistance information transmitted by a TSN bridge in the case of a transmission frame having a UL / DL / F TDD frame structure according to an exemplary embodiment of the present invention, where "F" refers to a transmission opportunity of a flexible nature. [Figure 8] 1 illustrates a description of a transmission opportunity along with information related to directional port pairs as an example nature of assistance information in accordance with an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] This disclosure describes a method for scheduling TSN flows in a communication system in a time-sensitive network.

[0052] The method is performed in a central network configuration entity.

[0053] The method comprises: - obtaining assistance information regarding a time granularity of a transmission opportunity from at least one TSN bridge having an internal time constraint; - scheduling a plurality of TSN flows by calculating time series of said TSN flows up to said time granularity based on the obtained assistance information; Includes.

[0054] The method is applicable to any bridge with internal time constraints, for example because it can use a time-division transmission medium. Such bridges with internal time constraints, from which assistance information is obtained, are referred to throughout this specification as "time-constrained TSN bridges". An example of such a bridge is a 5G system acting as a TSN bridge, also called a 5GS bridge. In this case, the transmission medium is a wireless medium. Hereafter, various exemplary embodiments are described taking into account the various possible time divisions of the transmission medium of the time-constrained TSN bridge. Naturally, the method does not exclude obtaining additional assistance information from additional TSN bridges, which may also have internal time constraints or, on the contrary, lack them, for the common purpose of scheduling multiple TSN flows. In fact, a time-sensitive network may include various sub-networks and various TSN bridges, one, some or all of which may have internal time constraints.

[0055] One possible time division of the transmission medium is shown in Figure 3. The frame 31 is on a large scale. Each frame can be divided into multiple slots 32, and each slot is finally divided into multiple transmission opportunities (TxOps) 33. For 5GS bridges, 5GS defines some numerical rules for slot formation. In a typical example (frequencies below 6 GHz), the frame duration is about 10 ms and the slot duration is 1 ms, so the transmission opportunity duration is about 140 μs. Considering a throughput of 50 Mbit / s, about 800 octets of data can be transmitted in one transmission opportunity.

[0056] The nature and depth of data from time-constrained TSN bridges that may form the support information associated with a CNC may vary depending on the structure of the current transmission frame.

[0057] Furthermore, the opportunity for improvement over the prior art in terms of taking into account the assistance information in the CNC in view of optimizing the delay in at least one TSN bridge is also variable based on: - the current transmission frame structure, and The nature and depth of support information sent by the TSN bridge to the CNC.

[0058] For a possible time division of the transmission medium shown in Fig. 3, a typical resource allocation at the base station, known in the art, is to define the scheduling of the next slot: This means that all packets 34, 35 arriving during slot n are transmitted earlier in slot n+1, as shown in Fig. 3a.

[0059] In current technology, the CNC calculates its TSN scheduling by considering the independent and dependent delays provided by the TSN bridges.

[0060] The load-dependent delay is a part of the load-dependent delay. dep can be calculated, for example, from the average throughput available in one slot, assuming given radio conditions and a given load, if the transmission medium is a wireless medium.

[0061] The independent delay is independent of the load and, in the current technology, includes the slot duration. Therefore, this independent delay D advertised by the time-constrained TSN bridge ind is usually defined by equation (1).

number

[0062] In other words, as can be seen by FIG. 3a, in the current technology the actual transmission time (TxDelay) 36 of a packet, defined as the interval between the arrival time and the transmission time of the packet, is always longer than the total duration of a slot.

[0063] As shown in FIG. 3b, in order to reduce the actual transmission time TxDelay 36, it is advantageous to be able to shift the packet arrival time in a given slot closer to the start of the next slot.

[0064] To do this, in this example, the CNC needs to more efficiently take into account the slotting of the TSN bridges when calculating the transmission time of a packet at each network device.

[0065] In this regard, in order for the CNC to be able to consider the independent delay of a time-constrained TSN bridge as possibly shorter than the total slot duration, the CNC must be able to consider the total slot duration T p It is necessary to have access to not only the IP address but also more specific information from the TSN bridge.

[0066] This more specific information relates to at least the time granularity of the transmission opportunities within a transmission frame.

[0067] To this end, in the case of slot-level alignment shown in FIG. 3b, the time-constrained TSN bridge provides assistance information to the CNC, which may include, for example, the following indications: - per TSN bridge: a transmission period T corresponding to the duration of a slot, as already defined p , and - Similarly for each TSN bridge: the offset T corresponding to the start of the slot, relative to the clock common to the TSN bridge and the CNC o .

[0068] According to this example, the support information T p and T o is a value associated with the TSN bridge as a whole. In other words, T p and T o is a value common to all port combinations of the TSN bridge that can be used as ingress and / or egress ports in this example.

[0069] Using this aiding information, the independent delays advertised by the TSN bridges to the CNC can be transformed as shown in equation (2).

number

[0070] As a result, the offset T that marks the start of the slot o and the time between the start of two consecutive slots T p By knowing, the CNC can compute time series of TSN flows that distinguish between transmission opportunities within each slot. Thus, in contrast to current techniques, such time series are computed to a time granularity that is less simple and more precise than that of a slot within a transmission frame. For example, the arrival time of a packet may be shifted towards the end of a given slot (and thus a later transmission opportunity within the slot), while a subsequent transmission time of said packet may be scheduled to the beginning of the next slot (and thus an earlier transmission opportunity within that slot).

[0071] Thus, the resulting transmission delay can be less than the full duration of a slot.

[0072] In the above example with time alignment at the slot level, the aiding information does not need to contain an indication regarding the internal composition of each slot, and so this can be hidden from the CNC.

[0073] However, the estimation of the independent delays at the CNC can be further improved by providing the CNC with an indication as to the internal composition of each slot as part of the aiding information.

[0074] To illustrate this aspect, another example is described hereinafter.

[0075] In this example, the TSN Bridge is considered to be operating in Time Division Duplex (TDD) mode, which divides each slot into A set of transmission opportunities available for the uplink transmission mode (UL TxOp), and - another set of transmission opportunities available for downlink transmission mode (DL TxOp); This means that the pattern can be written as

[0076] Assuming a static UL / DL split, such a framing can be as shown in Figure 4. This means that the UL / DL pattern is constant over time, with a period T p corresponds to a slot duration, and UL TxOps and DL TxOps are not or hardly ever interleaved.

[0077] In a known scenario, a scheduler in the base station can allocate resources to a packet in the current slot. In another known scenario, some pre-allocation of resources is done assuming periodic TSC traffic.

[0078] In the current technology as shown in FIG. 4a, the transmission delay 36 is longer than the entire duration of a slot, with the additional constraint that for a given packet, transmission of that packet can only occur during a transmission opportunity available for that packet's transmission mode (uplink or downlink).

[0079] In order to align the arrival times of packets as much as possible with the slotting of the transmission frame, it is possible, through assistance information from the TSN bridge, to inform the CNC that a TxOp has two different properties depending on the direction of data flow.

[0080] Thus, in such an example, the aiding information provided by the TSN bridge to the CNC is a transmission period T p and two offsets marking the start of the UL TxOp and the start of the DL TxOp, respectively.

number

number

[0081] However, such assistance information is not ideal: indeed, the CNC does not need to know the details of the transmission medium and the internal configuration of the TSN bridges, in particular identifying the use of a transmission opportunity as an uplink or downlink use is in principle a concept that the CNC does not know about.

[0082] Therefore, it is proposed to indicate a time offset per directional port pair in the TSN bridge to alert the CNC that the time constraints may differ depending on the data flow direction.

number

number

[0083] The assistance information provided by the TSN bridge to the CNC in this case may include the following indications: - per TSN bridge: a transmission period T corresponding to the full duration of the slot p , and -Directional port pair (P i ,P j ) : Offset to the clock common to the TSN bridge and CNC

number

[0084] T p and

number

number

number

[0085] This allows the CNC to minimize transmission delay 36 in the TSN Bridge, for example by scheduling the arrival 34 of a packet during a UL TxOp in a given slot and the transmission of such packet during the next UL TxOp in the next slot, as shown in Figure 4b. Conversely, considering the opposite flow, the arrival 35 of another packet can be scheduled during a DL TxOp in a given slot, and the transmission of such packet can be scheduled during the next DL TxOp in the next slot.

[0086] In yet another example, the flexibility of the 5G standard can be utilized in terms of dedicating TxOps within a slot to UL and DL.

[0087] One such example is shown in FIG.

[0088] In such an example, the CNC should know the details of the TxOp within a slot in order to align as many packet arrival times as possible with the transmission frame slotting.

[0089] Directional Port Pairs (P i ,P jFor each directional port pair, it is possible to provide the CNC with a bitmap corresponding to the TxOps that can be used for this directional port pair. Thus, a bitmap {1,1,0,1,0,0} could indicate that the slot contains 6 TxOps, but only the first, second and fourth are available to port P. i From Port P j It can be used for data flow towards

[0090] In this example, the assistance information provided to the CNC may include the following indications: - per TSN bridge: transmission period T corresponding to the slot duration p , and an offset T corresponding to the start of a slot, relative to a clock common to the TSN bridge and the CNC. o 51, and -Directional port pair (P i ,P j ) bitmap of available TxOps in slot62.

[0091] Typically, a time-constrained TSN bridge would in this scenario define one TxOp Bitmap 62 for DL ​​and one TxOp Bitmap 63 for UL, and in the assistance information provide one or the other for each directional port pair.

[0092] Alternatively, a directional port pair (P i ,P j For each TSN bridge, it is possible to provide the CNC with multiple possible slot configurations for a given TSN bridge combined with a corresponding index that points to one of these possible slot configurations.

[0093] As a result of such substitution, the assistance information provided to the CNC may include the following indications: -Transmission period T corresponding to the slot duration for each TSN bridge p , an offset T corresponding to the start of a slot, relative to a clock common to this TSN bridge and the CNCo , as well as different bitmaps corresponding to different available TxOp configurations, and -Directional port pair (P i ,P j ) by: Index into the TxOp bitmap to use.

[0094] Value T p and T p The independent delay (D ind ) can be calculated as defined in equation (2).

[0095] Based on the overall support information, the independent delay (D dep ) is preferably calculated as an "instantaneous" delay, i.e., if the transmission medium is a wireless medium, it can be calculated from the throughput of a single TxOp, assuming given wireless conditions and a given load equation (4).

number

number

[0096] Yet another example showing the high flexibility of the 5G standard is shown in Figure 7. As a further modification of the UL / DL patterns as shown in Figures 4 to 6, Figure 7 further introduces the concept of flexible TxOp(F). Flexible TxOps are assigned to UL or DL ​​transmissions at the last moment in the base station. That is, the slot structure can be shown in the control section at the beginning of each slot.

[0097] In this embodiment, the frame structure is still considered periodic, i.e., the slot structure is constant over time, but the TSN Bridge indicates which slots may be flexible. The TSN Bridge also indicates the direction (UL or DL) of each directional port pair. With this information, the CNC can determine the best UL / DL structure for a given set of streams.

[0098] Thus, in this example, the assistance information provided by the TSN to the CNC may include the following indications: - a transmission period T, corresponding to the duration of a slot, for each TSN bridge p , and an offset T that marks the start of this slot relative to the clock common to the 5GS bridge and the CNC. o 61, for each TSN bridge, a set of values ​​71 indicating the structure of a TxOp in said slot, each value being coded, for example, as follows: 0: TxOp is not available, 1: TxOp is available for direction d1 (e.g. DL TxOp); 2: A TxOp is available for direction d2 (eg, a UL TxOp). 3: TxOp is available in both directions (flexible TxOp), and -Directional port pair (P i ,P j ) a value 84 indicating the direction d1 or d2 of the directional port pair.

[0099] This supporting information is further illustrated in FIG.

[0100] The set of values ​​indicating the structure of the TxOp within a slot is a type of descriptive aid similar to the bitmap in the example of Figure 6, but with the addition that in this example it allows for more possible values, especially to allow a particular TxOp to be signalled as having flexibility.

[0101] Of course, instead of providing a single set of values ​​describing the structure of a TxOp in a given slot, a TSN bridge may provide the CNC with multiple possible sets of values ​​81, 82. In addition, the TSN bridge may provide the CNC with per-directional port indices 83 that indicate which of these possible sets of values ​​correspond, such that the CNC can select one unique associated set of values ​​for any given directional port pair of such a TSN bridge.

[0102] Similar to the example in Figure 6, the independent delay D advertised to the CNC by the TSN bridge ind can be calculated as defined in equation (2), whereas the dependent delay D dep is preferably calculated as the "instantaneous" delay, i.e. calculated from the throughput of one TxOp, assuming given radio conditions and a given load equation (4) when the transmission medium is a wireless medium.

[0103] Additionally, optionally, the CNC may indicate the selected slot structure back to the TSN bridge that issued such assistance information. This indication may be, for example, in the form of at least one or several sets of values ​​describing the flexible TxOp. The encoding may be similar to the encoding of the set of values ​​indicating the structure of the TxOp previously provided by the TSN bridge as part of the assistance information.

[0104] A further possibility that may be encountered in any of the above examples is that a TSN bridge may be built internally by some base stations, so potentially there can be one different TDD frame configuration per base station.

[0105] However, on the contrary, for example if the transmission medium is a wireless medium or radio spectrum regulatory rules in order to limit inter-base station interference may require that all base stations in a given TSN bridge have the same TDD frame structure.

[0106] Such unique requirements may also be indicated to the CNC by the TSN Bridge, for example by convention a unique TxOp description may be indicated as part of the assistance information.

Claims

1. 1. A method for scheduling a time sensitive network (TSN) flow in a communication system in a TSN including a wireless bridge of a 5G system, the method being performed in a central network configuration entity, the method comprising: Obtaining assistance information from at least one TSN bridge having an internal time constraint regarding a time granularity of a transmission opportunity within a transmission frame divided into slots, the TSN bridge being a radio bridge of the 5G system, the slots being divided into the transmission opportunities; scheduling the TSN flows by calculating a time series of a number of TSN flows up to the time granularity, knowing offsets marking the start of a slot and the time between the start of two consecutive slots based on the obtained aiding information; A method comprising:

2. 2. The method of claim 1, wherein the assistance information from the TSN bridge includes a period and an offset, the offset being defined relative to a clock common to the central network configuration entity and the TSN bridge.

3. 2. The method of claim 1, wherein the assistance information from the TSN bridge includes a time period and, for a number of directional port pairs, further includes a corresponding offset, the offset being defined relative to a clock common to the central network configuration entity and the TSN bridge.

4. The method of claim 2 , wherein the period corresponds to a slot duration and the offset indicates a start of a slot.

5. 4. The method of claim 3, wherein the period corresponds to a slot duration, and wherein a first offset indicates a start of a first group of statically assigned transmission opportunities in a first transmission direction and a second offset indicates a start of a second group of statically assigned transmission opportunities in a second transmission direction.

6. 5. The method of claim 4, wherein the assistance information from the TSN bridge further comprises an indication of an allocation of each transmission opportunity between a first transmission direction and a second transmission direction within a slot.

7. The method of claim 6 , wherein the indication comprises a corresponding bitmap of availability status of each transmission opportunity within a slot for a number of directional port pairs.

8. The indication may include: a plurality of bitmaps of availability status of each transmission opportunity within a slot for a given transmission direction, the bitmaps corresponding to a given possible slot structure; a corresponding index into a particular bitmap of the plurality of bitmaps for a plurality of directional port pairs; The method of claim 6, comprising:

9. The assistance information from the TSN bridge: an indication of a property corresponding to each transmission opportunity, each said property being flexible or fixed; the flexible property being associated with a flexible use of a first transmission direction and a second transmission direction; an indication that the fixed nature is associated with a fixed use of only one transmission direction between the first transmission direction and the second transmission direction; an indication of corresponding transmission directions between the first transmission direction and the second transmission direction for a plurality of directional port pairs; The method of claim 4 further comprising:

10. The assistance information from the TSN bridge: a plurality of sets of values ​​corresponding to a given possible slot structure and indicating an availability status of each transmission opportunity within a slot for each of a first transmission direction and a second transmission direction; an index corresponding to a particular set of values ​​among the plurality of sets of values ​​for a plurality of directional port pairs, and an indication of a corresponding transmission direction between the first transmission direction and the second transmission direction; The method of claim 4 further comprising:

11. A central network configuration entity of a communication system in a time sensitive network (TSN) including a wireless bridge of a 5G system, the central network configuration entity comprising: Obtaining assistance information from at least one TSN bridge having an internal time constraint regarding a time granularity of a transmission opportunity within a transmission frame divided into slots, where the TSN bridge is a radio bridge of the 5G system, and the slots are divided into the transmission opportunities; scheduling TSN flows by calculating a time series of a plurality of TSN flows up to said time granularity, knowing offsets marking the start of a slot and the time between the start of two consecutive slots based on said obtained aiding information; A central network configuration entity configured to:

12. A communication system in a time sensitive network (TSN), said communication system comprising at least one TSN bridge having an internal time constraint and a central network configuration entity according to claim 11.

Images