WO2018141945A1

WO2018141945A1 - Control plane message prioritization mechanism

Info

Publication number: WO2018141945A1
Application number: PCT/EP2018/052742
Authority: WO
Inventors: Devaki Chandramouli; Colin Kahn; Philippe Godin
Original assignee: Nokia Technologies Oy
Priority date: 2017-02-06
Filing date: 2018-02-05
Publication date: 2018-08-09

Abstract

A method and corresponding apparatuses are disclosed, the method comprising determining, from information received in a control plane message, a priority for a traffic slice in a network, wherein traffic slice priority reflects latency requirements and subscriber agreements, assigning transport priority to pending control plane traffic associated with the control plane message according to the determined priority and selecting a transport protocol or transport configuration according to the assigned transport priority, forwarding at least the information to a next destination in the network for the control plane traffic and forwarding received control plane traffic associated with the control plane message to the next destination in the network according to the assigned traffic priority.

Description

CONTROL PLANE MESSAGE PRIORITIZATION MECHANISM

TECHNOLOGICAL FIELD:

[0001 ] The described invention relates to wireless communications, and more particularly to control channel signaling that can be used to prevent blocking of signaling between a user equipment (UE) and a core network when connected to multiple core network gateways, a

BACKGROUND:

[0002] Wireless radio access technologies continue to be improved to handle increased data volumes and larger numbers of subscribers. The 3GPP organization is developing a new radio system (commonly referred to as NR or 5^th Generation/5G) to handle peak data rates of the order of ~10Gbps (gigabits per second) while also satisfying ultra-low latency requirements that are not achievable in 4G. 5G intends to utilize both radio spectrum below 6 GHz and above 6GHz in the centimeter and millimeter-wave (mmWave) bands; and also to support massive MEVIO (m-MIMO), ultra reliable low latency communications (URLLC) and mobile broadband (MBB). M-MIMO systems are characterized by a much larger number of antennas as compared to 4G systems, as well as finer beamforming and a higher antenna gain.

[0003] FIG. 1 is a schematic overview of an example 5G radio access network (RAN) in which these teachings may be deployed. Rather than a conventional unitary cellular base station/eNB as is typical in 4G, the 5G system will more commonly have the conventional base station's functionality distributed among a baseband unit (BBU) 20 (which may be implemented as a single BBU or multiple interconnected BBUs) and one or typically multiple remote radio heads (RRHs) 30 each located up to a few kilometers from the BBU 20. Each RRH 30 is operationally connected to its BBU 20 via a wired or wireless bidirectional transmission link 25 referred to as a front haul (FH) link. Currently the BBU/RRH combination in 5G systems is referred to as a gNB. The UE 10 is in direct communication with one or more of the RRHs 30, which in the 5G system each RRH 30 would be operating as a transmission/reception point (TRP) of the gNB. The UE 10 may have active connections to more than one RRH 30, shown in FIG. 1 as two TX/RX beam pairs with two different TRPs/RRHs. There is a somewhat similar distribution of access node functionality in cloud- based radio access networks (C-RAN) that are currently being deployed at least for some LTE- based networks, though those systems typically use a different terminology than BBU and RRH. [0004] An important consideration in developing the NG/5G system is to provide networks tailored to different businesses and services. Business based network differentiation allows for networks that support both broadband data access and dedicated application verticals such as health-care monitoring and on-demand video service to a retail consumer device like a smartphone or tablet. Service based differentiation allows for the allocation of different network resources according to application quality of service (QoS) requirements such as URLLC and high data rates. To date the focus of this differentiation has been almost exclusively in the user plane where end-user packets are processed and in the control plane where slice dedicated session management and other control functions can provide services such as charging, user plane QoS control, lawful intercept control, bearer path management, etc. that are specific to the service or business use.

[0005] 3GPP TR 38.801 Vl.0.0 (2016-12) sets forth at section 8.1 that network slicing is a new concept in 5G to allow differentiated treatment depending on each customer requirements. Slicing enables Mobile Network Operators (MNO) to consider customers as belonging to different tenant types with each having different service requirements that govern in terms of what slice types each tenant is eligible to use based on Service Level Agreement (SLA) and subscriptions. That section of the document also stipulates that the radio access network (RAN) shall support QoS differentiation within a slice, and defines the core network (CN) as a common control plane entity in the next generation core (NG-C, which may contain both common control network functions (CCNFs) which (similar to the evolved packet core EPC in 4G/LTE systems), is common to all slices serving a UE, and other functions dedicated to specific slices. .

[0006] A problem arises in that addressing the user plane and the control plane do not necessarily result in a suitable end-to-end solution. In the user plane differentiation may use slice specific resources in the NG-RAN and NG-Core. In the control plane typically the mechanisms to implement slicing are separate in the NG-RAN and NG-Core. What has been missing in 4G and in proposals for 5G is a mechanism to prioritize control plane messaging and transport associated with the end-to-end businesses or services. This is necessary to fully separate different network slices. Embodiments of these teachings address this problem.

[0007] To the inventors' view the nearest solution in current networks involves local prioritization of signaling. Specifically, in the 4G RAN on the air- interface there are 3 different types of signaling radio bearers (SRBs): SRBO, SRB1 and SRB2 used for radio resource control (RRC). These bearers have different characteristics and carry different types of signaling. For example, SRB1 and SRB2 both carry non-access stratum (NAS) messages which are between the UE and the mobility management entity (MME), but SRB2 messages have a lower priority than SRB1 messages. But this is not suitable for an end-to-end solution in 5G because when these NAS messages are sent from the RAN to the MME on the SI -MME interface, there is no ability to propagate the air- interface prioritization to the S 1-MME interface. All UE-associated messages for a given UE, including NAS messages, must be sent in a single stream control transmission protocol (SCTP) stream that provides in-order delivery and retransmission when an error occurs. Prioritization according to business or service differentiation as 5G requires is not possible with that 4G prioritization scheme, where all messages from the same UE are treated equivalently over the SI -MME interface as well as over the north bound GPRS tunneling protocol control plane (GTP-C) interfaces. When these control plane messages are further forwarded in the core network, for example to a function in a network slice, if one were to adapt this 4G protocol to the 5G network slicing, operators may configure transport priorities based on local information but there is no propagation of priorities from application or service information available at the endpoints, which are the UE and typically some network server. Adapting the 4G prioritization will not be sufficient for 5G because there is no consistent mechanism to specify signaling priority end-to-end to support network slice differentiation for different business or services.

[0008] Relevant background teachings may be seen at the following documents:

• RP- 160671 by NTT DoCoMo entitled Study on NR New Radio Access Technology

[3GPP TSG RAN Meeting #71; Goteborg, Sweden; 7-10 March 2016]. R3-170211 by Nokia, Alcatel-Lucent and Shanghai Bell entitled pCR on slice-specific Traffic Prioritization [3GPP TSG-RAN WG3 NR Ad Hoc; Spokane, US; 16-20 January 2017].

R3- 170290 by Ericsson entitled TP regarding impacts of network slice awareness to RAN signaling [3GPP TSG-RAN WG3 NR Ad Hoc; Spokane, US; 16-20 January 2017].

3GPP TR 23.799 V14.0.0 (2016-12); Study on Architecture for Next Generation System (Release 14), sections 6.1 and 8.1 concerning network slicing.

3GPP TR 38.913 V14.1.0 (2016-12); Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14).

3GPP TR 38.801 Vl.0.0 (2016-12); Study on New Radio Access Technology: Radio Access Architecture and Interface) (Release 14).

3GPP TS 36.412 V13.0.0 (2015-12); SI Signaling Transport (Release 13).

BRIEF DESCRIPTION OF THE DRAWINGS :

[0009] FIG. 1 is a plan view illustration of a 5G radio access network in which embodiments of these teachings may be practiced to advantage.

[001 0] FIG. 2 is a high level schematic view of network architecture showing common AMF and slice-dedicated SMFs and UPFs in a 5G network that are relevant when considering end- to-end slices.

[001 1 ] FIG. 3 is similar to FIG. 2 but specifically showing control plane interfaces in the 5G network.

[001 2] FIG 4 is a process flow diagram of an embodiment of these teachings from the perspective of a node within the RAN or the core of the 5G network. [001 3] FIG. 5 is a diagram illustrating some components of certain entities of a radio network that include a radio access network and a core network, and components of a UE/mobile device, suitable for practicing various aspects of the invention.

DETAILED DESCRIPTION:

[0014] The embodiments below are in the context of a RAN and core network of a 5G communication system but this is only an example radio access technology and not a limit to the broader teachings herein. With respect to slicing for 5G systems some general principles have been agreed in 3GPP TR 38.801 and TR 23.799 referenced in the background section above. In particular it has been agreed that the slicing granularity was the protocol data unit (PDU) session and every signaled PDU session will have an associated slice identifier (ID) (see document R3- 170290 cited in the background section).

[001 5] The signaling corresponding to different PDU sessions could correspond to different slices, but these different slice-specific sessions could come in competition with one another if they are mapped over the same stream control transmission protocol (SCTP) stream. This is true even when these two PDU sessions are part of the same UE-associated signaling connection. Embodiments of these teachings address this specific problem.

[001 6] The very concept of slicing includes the need to bring differentiation among different traffic types; see the summary in the background section from section 8.1 of 3GPP TR 38.801. VI.0.0 (2016-12) sets forth at section 8.1 for differentiated treatment depending on customer requirements. In 5G at least the need of traffic differentiation is two-fold. The slice/service type component of the session management network slice selection assistance parameter information (SM-NSSAI) corresponds to different types of traffic which in 5G can be as diverse as URLLC and mobile Internet of Things (mIOT). It is widely accepted that typical IoT traffic can usually cope with large transmission delays while URLLC traffic carries very low latency requirements to support challenging real-time actions such as industrial applications like remote factory control. This means that the 5G traffic prioritization rules will need to enforce that traffic related to one slice carrying traffic of one priority like IoT traffic does not impede another slice carrying traffic of another priority like URLCC traffic.

[0017] The other need for traffic differentiation concerns different tenants. The Service Differentiator component of the SM-NSSAI identifies traffic which corresponds to different tenants, and different types of tenants can have different service requirements based on Service Level Agreements (SLA). Overlaying the different latency requirements for different types of traffic above, another layer of prioritization needs to be enforced concerning traffic belonging to different tenants in order to reflect the terms of the SLA between the mobile network operator (MNO) and each respective tenant. In this regard tenant can for example be a specific business and its SLA may stipulate different network slices for different traffic types associated with that business. The SLAs that control 5G services lead not only to specific policy enforcement per slice, but are likely to also lead to traffic prioritization among slices. These two components of SM-NSSAI indicate a need to apply traffic prioritization between slices.

[0018] Above it was discussed that an end-to-end solution for this prioritization of slices in 5G is needed; it is not an end-to-end solution if a slice is prioritized at one point in the network for example in the 5G core network but not prioritized at another point in the network such as the 5G radio access network or over the air interface with the wireless user device (user equipment or UE), or in the transport link between the 5G radio access network and the 5G core network In particular, one key feature of 5G slicing is to enable a UE to use multiple slices simultaneously. While doing this the UE will typically use different PDU sessions supported by different slice- specific SMF and UPF functions, which is illustrated at FIG. 2. The UE 10 is not part of any network but is served by the 5G network which interfaces the UE 10 to one or more broader data networks (DNs) 260, 262 such as the Internet and/or private data networks.

[0019] As with other cellular systems the 5G network may be considered in two parts: the RAN 220 which includes the radio access nodes (FIG. 1) that directly service the air interface with the UE 10; and the core network (CN) 240 that interfaces the radio access nodes to the DNs 260, 262 which can represent the Internet and a private data network for example. Within the CN 240 is an access management function (AMF) 242 that manages mobile access, similar to the mobility management entity in 4G systems; a session management function (SMF) 244 that handles the control plane management similar to a combination of the control-plane functions of the serving gateway and the packet data network gateway in 4G systems; and a user plane function (UPF) 246 that handles the user plane data similar to a combination of the user-plane functions of the serving gateway and the packet data network gateway in 4G systems. The specific interfaces labelled NGX at FIG. 2 represent 5G interfaces whose details are yet to be standardized and are subject to being re-named as the development of 5G progresses. FGI. 2 depicts the expected system architecture for 5G though this is not finally agreed. The AMF 242 is also referred to as a common core network function (CCNF, or sometimes common core control function) for this reason. Each SMF 244 and UPF 246 is specific to a given network priority slice. Unlike 4G systems, in 5G each interface between the RAN 220 and a DN 260, 262 is either control plane (such as NG 2 and NG11) or user plane 9such as NG1, NG3 and NG6).

[0020] In the network architecture of FIG. 2 the UE communication goes over common parts which are the RAN 220, interface NG2 and AMF 242/CCNF; and separately over slice- dedicated (slice- specific) network parts which are the SMF 244, UPF 246 and user plane interfaces NG-6. As previously note, in order to keep the end-to-end prioritization brought by the slice-dedicated parts, the common/shared parts shall also introduce prioritization across slices. It follows then that prioritization over the next generation core (NG-C) is necessary for slicing to be implemented as an end-to-end solution.

[0021 ] To address slicing prioritization at the NG-C SCTP level, it is prudent to review how control plane traffic was handled in the LTE network. In LTE, control plane traffic on the S 1- C interface for a given UE-associated signaling connection is required to use no more than one SCTP stream; 3GPP TS 36.412 sets forth at section 7 that "A single UE-associated signalling shall use one SCTP stream and the stream should not be changed during the communication of the UE-associated signalling. " [0022] But this will not be suitable for 5G. In order to ensure slice-specific traffic differentiation, embodiments of these teachings change the above LTE principle so that the signalling traffic of a given UE should be able to use multiple different SCTP streams when that traffic corresponds to transactions of different slices. To do otherwise would allow one slice with urgent or low latency delivery requirement such as URLCC traffic to be blocked when at the head of the traffic line there is a signalling peak of non-delay sensitive traffic such as IOT traffic. Changing this LTE principle for embodiments of these teachings does not prevent traffic from two different UEs and associated with the same slice type from sharing of the same SCTP stream. Avoiding such head of line blocking of priority traffic is an aspect of these teachings that embodiments of these teachings address by making allocation of SCTP streams more flexible by allowing slice-dedicated SCTP streams to be allocated over the NG- C. If the Control Plane is sliced for a given UE, it shall be possible to serve the signaling traffic by different SCTP streams over NG-C.

[0023] Embodiments of these teachings implement this by coordinating the prioritization of control plane signaling according to information provided by an endpoint (UE or server in the network) that is aware of the application, business and/or service objectives of a network slice/service provided to the UE. The endpoint conveys this information via an indication that is propagated through the control plane signaling path. The information is used to choose one or more SCTP streams and set the prioritization used to allocate transport, network and data- link layer resources according to the business and service needs.

[0024] Consider an example. If an application on a UE requires a low latency service, the UE or application would provide a low latency indication that is propagated on the signaling path from UE 10 to RAN 220 to the Common Core Control Function (AMF 242) to Low Latency Slice Specific Control Function (the SMF 244 associated with low latency traffic control) to the Application Server (at the DN 260, 262 if needed). That same indication is then used to allocate transport resources and priorities for the user plane data. Similarly, if a business has dedicated resources allocated in a slice, signaling traffic associated with that business may be accorded an appropriate priority over a similar path - from UE to RAN to Common Core Control Function to business specific Slice Control Function to Application Server like the above example for the low latency service.

[0025] FIG. 3 is an adaptation of FIG. 2 to more clearly show the different slice-specific functions in the CN 240; slice 1 and slice 2 represent different priorities and in a practical system there will be more than only the two slice priorities illustrated there. The UE 10 communicates with an application (server, in the DN 260) through a 5G network consisting of a RAN (gNB) 220, a Common Control Network Function 348 and slice- specific network functions 350. The UE 10 provides the user with more than one service, for example broadband data access and health monitoring. The network has been configured to support these two services in different network slices (Slice 1 and Slice 2 in FIG. 3) that are tailored to the application needs. Slice 1 and Slice 2 are shown explicitly for the core network. Slice 1 / Slice 2 separation is embedded within the RAN 240 but this is not shown within FIG. 3. The Common Control Network Function 348 provides the UE 10 rather than application specific functions like the common 4G function of tracking UE location.

[0026] In embodiments of these teachings, in addition to the control function the signaling transport is also sliced so that the appropriate priority is consistently given to different signaling messages as they traverse the network. The UE 10 first itself uses its knowledge of the message purpose and destination/application to prioritize transmission on the air-interface 10 in FIG. 3, and selects the appropriate mechanism. To do this the UE 10 may select among different protocol options for sending the message, or it may use segregated air-interface slices. For example, for a fast- setup slice, the UE may use a dedicated protocol designed for this purpose and subsequently instantiated in the realization of the RAN 220.

[0027] In a particular embodiment for the uplink, when the UE sends the signaling message to the RAN 220, it provides information in the message header or as part of radio resource control (RRC) message that indicates the prioritization that should be used for subsequent control plane signaling. Examples of such a RRC message include a RRC establishment cause or service type message. There are several implementations of what this header information may indicate, for example it may:

• directly indicate relative priority (for example: high, medium or low).

• indicate service characteristics that need be supported for the network slice that is associated with the signaling (for example: low latency / fast setup).

• indicate a business (for example, a specific bank) or business purpose (for example, a realtime e-health monitor application).

• indicate a previously configured network slice.

• indicate the specific nature and importance of the message.

[0028] Alternatively, the UE may indicate the control plane priority needed as part of network slice selection assistance parameter information (NSSAI). The UE may also indicate this in a non-access stratum (NAS) message sent from the UE to the core control plane.

[0029] This information is then received in the RAN 220 which uses it to set the priority and help select the forwarding protocol, if the message is to be further forwarded which will typically be the case for messages other than those used for RAN management such as buffer status reports, beam status reports, resource requests and the like. The RAN 220 also includes the information it received from the UE in the header of the message it sends, or as part of the initial message if that initial message is simply forwarded, towards the core network control plane so other functions can repeat this process as well as configure signaling options and assign transport priority for signaling messages that need to be forwarded to the next node (if any). At each hop, the information in whatever form is mapped locally to select and configure control plane interfaces.

[0030] A specific example will further illustrate the concept. Assume a UE 10 has both broadband data access, and health monitoring. The health monitoring service has been allocated dedicated resources in "Slice 2" since it is both deemed more critical than broadband data access and is associated with a health monitoring business that in this example has arranged for dedicated network resources to ensure the quality and reliability that business deems necessary. Broadband data is supported though separate "Slice 1" resources in the RAN 220 and in the core network 240. Referring to FIG. 3, there are distinct slice-specific entities 350 for slice 1 and slice 2 only in the slice-dedicated portion of the core network 240, though in the common portion 348 as well as in the RAN 220 these different slices are still distinguished from one another but within the common functions that handle all different types of slices.

[0031 ] When the UE 10 in this example sends a message to the gNB in the RAN 220, the indication in the header or RRC message may for example be that the message is associated with "Slice 1", Slice 2", or a Common CP Function (CCF). The gNB may use that indication to map the message to:

• an II interface instance (see FIG. 3);

• an SCTP Association on the II interface; or

• a stream within an SCTP Association on the II interface.

[0032] The gNB may also use that indication to message-mark packets at the transport IP layer (beneath SCTP) so that transport quality of service (QoS) will be provided for the message. This in itself is a radical departure from 4G operations. If the II interface shown at FIG. 3 is considered comparable to the SI interface in 4G between the eNB and the MME, that SI interface allows no option to differentiate UE-associated signaling from the same UE in this manner. In addition, for embodiments of these teachings the network may also use the indicator to map subsequent uplink and downlink control-plane messages for the same UE and/or on the same connection.

[0033] Continuing with the above example, the indication that was received by the gNB on the 10 interface is forwarded with the message received on that II interface, either in the header or as part of the II message content. For those messages that must be forwarded by the common control function (CCF) 348 on 12 to a slice- specific function 350, the same process is repeated. The CCF 348 uses the indication received on the II interface to locally map the indication to an 12 configuration, for example by setting interface parameters such as QoS markings.

[0034] The above process may be repeated for messages exchanged between control functions within a slice 350, as indicated by the interface 13 between same-slice function pairs. This same technique may also be used to set priority for signaling exchange with an application on interface 14 as shown at FIG. 3.

[0035] The above examples were in the uplink direction with UE-originated signaling, but the entire process may also operate in reverse for UE-terminated signaling. In this regard an application in the data network 260, 262 may use an interface or specifically an application programming interface (API) to "request" a service from the network. A similar such request in a 4G network would be a request on the receive interface for QoS, or use of an API by an IoT device using the 4G Services Capability Exposure Framework (SCEF). For embodiments of these teachings, a header field in the request received at the core network 240 from the application on the 14 interface can indicate the priority of the signaling message, which may be honored by subsequent nodes that execute a resultant procedure similar as detailed above for UE-originated messages. Alternatively, a message generated within Slice 1 or Slice 2 in the CN 240 may be marked with an indication that is then propagated on subsequent interfaces 13, 12 and II towards the gNB.

[0036] An important aspect of these teachings is that for uplink and downlink control plane traffic, at the RAN 220, prioritization is done by assigning traffic associated with different slices to different transport layer SCTP Associations or different SCTP streams and it is transported on these streams along the NG2 interface of FIG. 2 or the II interface shown at FIG. 3. Note also that these SCTP streams are priority- slice specific but not necessarily UE- specific, meaning the RAN 220 can put traffic from two or more different UEs onto the same SCTP stream so long as that traffic is all the same network- slice priority. This may not be possible in every case, for example if the SLA's dedicated resource commitment requires 1 dedicated SCTP stream. [0037] Traditionally cellular networks did not necessarily 'trust' the UE since the air interface is generally less secure than the inter-node communications within the 5G network. Regardless, the decision has been made in 5G to allow the UE to provide at least some assistance for the network slice selection, for example via a set of parameters the UE sends to the network to select the set of RAN and CN part of the network slice instances (NSIs) for the UE. Embodiments of these teachings use this parameter information/network slice assistance information provided by the UE (or the CN depending on the direction of traffic), which unambiguously identifies one or more of the pre-configured network slices in the public mobile land network, to prioritize packets on the gNB<->AMF interface (NG2 interface at FIG. 2; II interface at FIG. 3; similar to the Sl-C (Sl-mme) interface in 4G between the eNB and the MME). The information is sent within the control plane such as via RRC signaling, which in general is made secure in that the UE must first authenticate, and the RRC signaling that carries this information will preferably be encrypted and integrity protected by the packet data convergence protocol (PDCP) layer in the RAN.

[0038] In general the information that governs the prioritization of signaling traffic is use- case driven and comes from knowledge in the UE or application server. The information is also propagated end-to-end so each node can independently determine how to prioritize the signaling. For example on the gNB to AMF interface (NG2 in FIG. 2; II in FIG. 3) different SCTP streams may be used to differentiate signaling whereas on the AMF to SMF interface (NG10 in FIG. 2; 12 in FIG. 3) it may be that only different IPv6 Traffic Classes may be used.

[0039] Traditionally signaling messages that control the setup of bearers, the establishment of user sessions, authentication and authorization, handover, anchor relocation, and so forth were considered to be very different in kind from user plane data, and this is true as far as it goes for traditional cellular systems like 4G and previous 3GPP generations. But in 5G user data and control plane signaling are sent via different interfaces using different protocol stacks. Furthermore the user data priority may be very different from signaling message priority, even for signaling messages associated with an application that generates the user data. Since about the time of 2G there has been priority (QoS) associated with user plane data. But even in 4G there is no differentiation among signaling messages for a UE; for example on the SI interface between the eNB and the MME there is no choice but to send all control plane messages associated with a UE with the same priority.

[0040] In this regard slicing in 5G is a radical departure as it involves slicing the user plane (dedicated user-plane functions and RAN resources) and also slicing the core network control plane (dedicated session management function (SMF) and other functions). To this general outline these teachings add the ability to prioritize signaling (control plane messages) differently for different slices, which is particularly valuable for the case when a UE is associated with more than one slice and signaling/control plane traffic associated with one slice is of greater importance than that associated with another slice as demonstrated in just such an example above.

[0041 ] Advantages of these teachings over 4G systems are most manifest at the gNB- AMF interface where prioritization is done by assigning control plane traffic associated with different slices to different transport layer SCTP Associations or different SCTP streams. In the similar eNB-MME interface of 4G that is simply not an option.

[0042] One technical effect of embodiments of these teaching is they complete implementation of the 5G slicing function, which prior to these teachings lacked a consistent mechanism to slice the control plane transport, resulting in a further lack of ability for an individual UE to have multiple different end-to-end slices simultaneously. In 4G a single UE could have multiple slices but there was no differentiation for the signaling so the slices were not end-to-end. Another technical effect is they enable a service configured as high priority to become functional by differentiating its signaling from lower priorty signaling when the network control plane becomes congested. These teachings do this by allowing the signaling associated with high priority services to be handled separatly from signaling associated with lower priority service. A Peripheral technical effect of this is that relaibility is improved for those high priority services because the contention for resources between high and low priority services are avoided by these teachings.

[0043] FIG. 4 is a process flow diagram that represents a method and additionally represents steps or portions of computer program executable code that may be used to implement these teachings when embodied on some tangible computer readable memory or memories, and additionally represents actions taken by a host device such as a gNB or the AMF 242 in the core network (or other entities/nodes in the RAN or core network) when one or more processors executes such stored computer executable code.

[0044] Since the information in the control plane messages as detailed above is originated at either the server (application) or the UE depending on the direction of the message/data flow, FIG. 4 begins with the network entity receiving that first control plane message that is used to establish which slice, or to initiate a new slice if there is not already a pre-existing slice of the proper priority, the user plane data is to be transported on. FIG. 4 begins at block 402 at which the network entity determines, from information received in a control plane message, a priority for a traffic slice in a network. In this regard the traffic slice priority is more than simply 4G- type QoS, the traffic slice priority reflects latency requirements, subscriber agreements or other business agreements (for example, an agreement with a bank or other business entity that is not necessarily a subscriber), for example if the SLA requires dedicated resources. At block 404 the network entity assigns transport priority to pending control plane traffic associated with the control plane message according to the determined priority. At block 405 as a result of determining the priority associated with a control plane message, the network entity may select an appropriate transport, for example it may select a specific SCTP association or SCTP stream for transport of the message to the next network entity. Block 406 finds the network entity forwarding at least the information mentioned at block 402 to a next destination in the network for the control plane traffic, so for example if the control plane message of block 402 is UE- initiated and the network entity performing the steps of FIG. 4 is a gNB the next destination may be the AMF 242 in the core network 240; else if the control plane message of block 402 is initiated at the network server and the network entity performing the steps of FIG. 4 is a SMF 244 the next destination may be the AMF 242 and also the UPF 246 (so it may know the priority for handling the control plane data). Finally at block 408 the network entity performing steps of FIG. 4 forwards the control plane traffic it does receive, and which is associated with the control plane message of block 402, to the next destination in the network according to the assigned traffic priority and the selected transport configuration.

[0045] As detailed above with more particularity, assigning the transport priority as block 404 states may in some embodiment further comprise allocating network resources according to the assigned traffic priority for transport of the received control plane traffic that is associated with the control plane message. This is an ongoing dynamic process as user data is received, not to imply that all resources for all the relevant control plane traffic that is to be carried on the SCTP stream are allocated in a block at one given instant in time. As further detailed above particularly for the case the gNB is performing the steps of FIG. 4, the block 404 assigning of transport priority may further comprise selecting a transport protocol or transport configuration according to the assigned transport priority, and this selecting can be implemented as selecting a SCTP stream or a SCTP association.

[0046] In various examples above the control plane message of block 402 could be a RRC message or a NAS message, and in some of the examples the traffic slice priority was determined from information in such messages that indicates relative priority; service characteristics that need be supported; a specific business; a specific business purpose; a previously configured traffic slice in the network; and/or a specific nature and importance of the control plane message.

[0047] In a specific 5G embodiment above, after assigning the traffic priority at block 402 there is then assigned a single SCTP stream that is dedicated to the traffic slice priority, and this SCTP stream can be established in response to seeing at block 402 a need for a slice with that priority or it may be a pre-existing/already-established network slice that has the requisite priority. In either case there is a SCTP stream assigned to the control plane data associated with the control plane message of block 402, and control plane traffic that the network entity performing the steps of FIG. 4 receives is forwarded to the next destination in the network on the assigned SCTP stream. If one considers the network entity performs the steps of FIG. 4 on two different time- overlapping occasions and the data flow is either to different UEs or originated from different UEs and has the same traffic slice priority, then these may be carried on the same slice such that control plane traffic originated by these different users and having a same traffic slice priority is forwarded to the next destination in the network using the same assigned SCTP stream.

[0048] FIG 5 is a high level diagram illustrating some relevant components of various communication entities that may implement various portions of these teachings, including a base station identified generally as a radio network access node 21 (shown at FIG. 1 as the RRH 20 plus the BBU 30), a core network entity 40 for which some examples are shown at FIGs. 2-3, and a user equipment (UE) 10. In the wireless system 530 of FIG. 5 a communications network 535 such as a 5G network (that includes both RAN and CN) is adapted for communication over a wireless link 532 with an apparatus, such as a mobile communication device which may be referred to as a UE 10, via a radio network access node 21 which may be implemented as multiple entities such as the BBU and RRHs shown at FIG. 1. The core network 535 includes one or multiple entities 40 that provides connectivity with other and/or broader networks such as a publicly switched telephone network and/or a data communications network (e.g., the internet 538). FIGs. 2-3 illustrate network functions that process network slices in common and slice-specific functions that process them separately; while shown as different slice-specific functions in FIGs. 2-3 these different functions may in some deployments be embodied in the same physical entity or distributed entities that are not physically separated according to the illustrated functions.

[0049] The UE 10 includes a controller, such as a computer or a data processor (DP) 514 (or multiple ones of them), a computer-readable memory medium embodied as a memory (MEM) 516 (or more generally a non-transitory program storage device) that stores a program of computer instructions (PROG) 518, and a suitable wireless interface, such as radio frequency (RF) transceiver or more generically a radio 512, for bidirectional wireless communications with the radio network access node 21 via one or more antennas. In general terms the UE 10 can be considered a machine that reads the MEM/non-transitory program storage device and that executes the computer program code or executable program of instructions stored thereon. While each entity of FIG. 5 is shown as having one MEM, in practice each may have multiple discrete memory devices and the relevant algorithm(s) and executable instructions/program code may be stored on one or across several such memories.

[0050] In general, the various embodiments of the UE 10 can include, but are not limited to, mobile user equipments or devices, cellular telephones, smartphones, wireless terminals, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

[0051 ] The radio network access node 21 also includes a controller, such as a computer or a data processor (DP) 524 (or multiple ones of them, particularly in the case of stacked BBUs), a computer-readable memory medium embodied as a memory (MEM) 526 that stores a program of computer instructions (PROG) 528, and a suitable wireless interface, such as a RF transceiver or radio 522, for communication with the UE 10 via one or more antennas. The radio network access node 21 is coupled via a data/control path 534 to the core network 40. The radio network access node 21 may also be coupled to other radio network access nodes (ANs) 534 via data/control path 536.

[0052] Entities or nodes in the core network 40 include a controller, such as a computer or a data processor (DP) 544 (or multiple ones of them), a computer-readable memory medium embodied as a memory (MEM) 546 that stores a program of computer instructions (PROG) 548. [0053] At least one of the PROGs 518, 528 is assumed to include program instructions that, when executed by the associated one or more DPs, enable the device to operate in accordance with exemplary embodiments of this invention. That is, various exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP 514 of the UE 10; and/or by the DP 524 of the radio network access node 21; and/or by hardware, or by a combination of software and hardware (and firmware).

[0054] For the purposes of describing various exemplary embodiments in accordance with this invention the UE 10 and the radio network access node 21 may also include dedicated processors 515 and 525 respectively.

[0055] The computer readable MEMs 516, 526 and 546 may be of any memory device type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs 514, 524 and 544 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples. The wireless interfaces (e.g., RF transceivers 512 and 522) may be of any type suitable to the local technical environment and may be implemented using any suitable communication technology such as individual transmitters, receivers, transceivers or a combination of such components.

[0056] A computer readable medium may be a computer readable signal medium or a non- transitory computer readable storage medium/memory. A non-transitory computer readable storage medium/memory does not include propagating signals and may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Computer readable memory is non-transitory because propagating mediums such as carrier waves are memoryless. More specific examples (a non-exhaustive list) of the computer readable storage medium/memory would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0057] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

[0058] A communications system and/or a network node/base station may comprise a network node or other network elements implemented as a server, host or node operationally coupled to a remote radio head. At least some core functions may be carried out as software run in a server (which could be in the cloud) and implemented with network node functionalities in a similar fashion as much as possible (taking latency restrictions into consideration). This is called network virtualization. "Distribution of work" may be based on a division of operations to those which can be run in the cloud, and those which have to be run in the proximity for the sake of latency requirements. In macro cell/small cell networks, the "distribution of work" may also differ between a macro cell node and small cell nodes. Network virtualization may comprise the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization may involve platform virtualization, often combined with resource virtualization. Network virtualization may be categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to the software containers on a single system. [0059] The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3GPP Third Generation Partnership Project

AMF access management function

BBU baseband unit

CCNF common core network function

DN data network

E-UTRAN evolved UMTS radio access network

gNB base station of a 5G system

IoT internet of things

LTE long term evolution (of E-UTRAN; also referred to as 4G)

MBB mobile broadband

m-MIMO Massive Multiple-Input Multiple Output

MNO mobile network operator

NAS non-access stratum

NG next generation (also referred to as 5G)

NSSAI network slice selection assistance parameter information

PDU protocol data unit

QoS quality of service

RAN radio access network

RRC radio resource control

RRH remote radio head

SCTP stream control transmission protocol

SMF session management function

UE user equipment

UMTS universal mobile telecommunications service

UPF user plane function

URLLC ultra-reliable low latency communications

Claims

CLAIMS: What is claimed is:

1. A method comprising:

determining from information received in a control plane message a priority for a traffic slice in a network, wherein traffic slice priority reflects latency requirements and subscriber agreements;

assigning transport priority to pending control plane traffic associated with the control plane message according to the determined priority and selecting a transport protocol or transport configuration according to the assigned transport priority;

forwarding at least the information to a next destination in the network for the control plane traffic; and

forwarding received control plane traffic associated with the control plane message to the next destination in the network according to the assigned traffic priority.

2. The method according to claim 1, wherein assigning the transport priority further comprises allocating network resources according to the assigned traffic priority for transport of the received control plane traffic associated with the control plane message.

3. The method according to claim 1 or 2, wherein selecting the transport configuration comprises selecting a SCTP stream or selecting a SCTP association.

4. The method according to any of claims 1-3, wherein the control plane message is one of a radio resource control message and a non-access stratum message.

5. The method according to any of claims 1-4, wherein the information indicates at least one of:

relative priority;

service characteristics that need be supported;

a specific business; a specific business purpose;

a previously configured traffic slice in the network; and

a specific nature and importance of the control plane message.

6. The method according to any of claims 1-5, wherein the method further comprises, after assigning the traffic priority, assigning a single stream control transmission protocol (SCTP) stream that is dedicated to the traffic slice priority, and wherein the received control plane traffic is forwarded to the next destination in the network on the assigned SCTP stream.

7. The method according to claim 6, wherein control plane traffic originated by different users and having a same traffic slice priority is forwarded to the next destination in the network using the same assigned SCTP stream.

8. An apparatus comprising at least one processor and at least one memory tangibly storing a computer program; wherein the at least one processor is configured with the at least one memory and the computer program to cause the apparatus to perform the method according to any of claims 1-7.

9. A computer readable memory tangibly storing a computer program that when executed causes a host network node to perform the method according to any of claims 1-7.