CN110786048A

CN110786048A - Method and system for switching between systems

Info

Publication number: CN110786048A
Application number: CN201780092395.4A
Authority: CN
Inventors: 周晓云; 李振东
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2017-06-20
Filing date: 2017-06-20
Publication date: 2020-02-11
Also published as: WO2018232605A1

Abstract

According to an embodiment, a method for facilitating handover of a user equipment from a first network using a first radio access network to a second network using a second radio access network involves: receiving a context for a connection of a user equipment via a first network, wherein the context comprises a bearer identifier of the connection; deriving a quality of service flow identifier from the bearer identifier; and transmitting the quality of service flow identifier to the second network.

Description

Method and system for switching between systems

Technical Field

The present disclosure relates generally to wireless communications, and more particularly, to methods and systems for facilitating inter-system handovers.

Background

Currently, long term evolution ("LTE") systems use a packet-based communication scheme called enhanced packet system ("EPS"), which is a connection-oriented transport network that needs to rely on virtual connections between endpoints (e.g., between a user equipment ("UE") and a packet data network gateway ("P-GW"). This virtual connection is called a PDN connection. A PDN connection may provide QoS support over one or more virtual connections named "EPS Bearer" (EPS Bearer), which provides "Bearer service" (epstearer), i.e. a transport service with specific quality of service (QoS) characteristics. EPS relies on Internet Protocol (IP) packets for communication.

In the currently proposed embodiment of the new wireless ("NR") network, the UE receives service through a protocol data unit ("PDU") session, which is a logical connection between the UE and the NR data network. The NR supports various types of PDU sessions such as IPv4, IPv6, ethernet, etc. Unlike EPS. A PDU session may provide QoS support through one or more virtual connections called "QoS flows. QoS flows are the finest granularity of QoS differentiation in a PDU session.

Because LTE and NR networks will likely co-exist for some time, it is important to ensure that a UE can successfully handover between a network using LTE radio access technology ("RAT") and a network using NR RAT. One area that needs to be addressed is the difference between how QoS is handled by LTE and how QoS is handled by NR.

Drawings

While the appended claims set forth the features of the present technology with particularity, the technology, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings of which:

fig. 1 is a diagram of a system in which various embodiments of the present disclosure are implemented.

Fig. 2 illustrates an example hardware architecture according to an embodiment.

Fig. 3 shows an example of a non-roaming architecture for interworking between an LTE data network and an NR data network.

Fig. 4 shows an example of two unicast EPS bearers.

Fig. 5 shows the format of the TFT information element.

Fig. 6 shows the format of the packet filter list.

Fig. 7 illustrates the general principles for classification and marking of user plane traffic and mapping of QoS flows to AN resources.

Fig. 8 illustrates an example EPS attach procedure in accordance with an embodiment.

Fig. 9 shows an example of a dedicated EPS bearer activation procedure according to an embodiment.

Fig. 10 shows an example handover procedure from EPS to 5GS according to an embodiment.

Fig. 11 shows an example of EPS bearer id concatenation with packet filter id according to an embodiment.

Fig. 12 shows an example PDU session modification flow in PCF triggered 5GS, according to an embodiment.

Fig. 13 shows an example of QoS mapping from a 4G network to a 5G network according to an embodiment.

Detailed Description

The present disclosure is generally directed to a method for facilitating handover of a user equipment from a first network using a first radio access technology to a second network using a second radio access technology. According to an embodiment, a computing device receives, on a first network (e.g., an EPS data network), a context for a packet connection of a user equipment, the context comprising a bearer identifier of the packet connection. The computing device derives a quality of service flow identifier (quality of service flooding) from the bearer identifier and transmits the quality of service flow identifier to the second network (e.g., a 5GS data network).

In an embodiment, the computing device derives a quality of service rule identifier (quality of service rule identifier) from the packet filter identifier or the packet filter identifier and the bearer identifier, and sends a protocol data unit session modification request (protocol data unit session modification request) including the quality of service rule identifier to the second network.

When a UE accesses data services via EPS or 5GS, QoS support for the UE is important in order to ensure a good user experience. Because the QoS mechanisms supported in EPS and 5GS are different, more specific embodiments described herein relate to methods and systems for coordinating these differences in order to ensure seamless handover between two different types of networks.

According to an embodiment, a method for facilitating handover of a user equipment from a first network using a first radio access network to a second network using a second radio access network involves receiving a context (context) for a connection of the user equipment via the first network, wherein the context includes a bearer identifier of the connection, deriving a quality of service flow identifier from the bearer identifier, and transmitting the quality of service flow identifier to the second network.

Table 1 lists various abbreviations used in the present disclosure as well as their expanded forms.

TABLE 1

Fig. 1 depicts a wireless communication system 100, which includes a wireless base station 102 and a UE 104. In an embodiment, the wireless communication system 100 has many components not depicted in fig. 1, including other base stations, other UEs, wireless infrastructure, wired infrastructure, and other devices common in wireless networks. Example embodiments of the UE include any device capable of wireless communication, such as smartphones, tablets, laptops, and non-traditional devices (e.g., home appliances or other parts of the "internet of things"). The base station 102 and the UE 104 may sometimes be referred to herein as "communication nodes. Thus, "communication node" encompasses both types of devices.

Fig. 2 illustrates the basic (computing device) hardware architecture found in both the base station 102 and the UE 104, according to an embodiment. The base station 102 and the UE 104 also have other components, some of which are common to both, and others of which are not. The hardware architecture depicted in fig. 2 includes logic 202, memory 204, transceiver 206, and one or more antennas, represented by antenna 208. Each of these elements is communicatively linked to each other via one or more data paths 210. Examples of data paths include wires, conductive paths on a microchip, and wireless connections. Measurements made by the communication node (e.g., measurements for each instance of measurements made by the UE, as described below) may be stored in memory 204 (e.g., in a data structure such as a table). Such measurements may include, for example, strength of a signal (e.g., a reference signal) received from another communication node (e.g., strength of an RS received by the UE from the base station), signal strength measured by the remote communication node from the original communication node (e.g., UE signal strength as measured by the base station and reported back to the UE), and BLER.

The term "logic circuit" as used herein means a circuit (a type of electronic hardware) designed to perform a complex function defined in terms of mathematical logic. Examples of logic circuitry include a microprocessor, controller, or application specific integrated circuit. When the present disclosure relates to an apparatus that performs an action, it should be understood that this may also mean that logic integrated with the apparatus is actually performing the action.

Possible implementations of the memory 204 include: a volatile data store; a non-volatile data store; an electrical storage; a magnetic memory; an optical memory; random access memory ("RAM"); a cache memory; and a hard disk drive.

The following description will sometimes refer to a base station and a UE without specific reference to fig. 1. However, it should be understood that all methods described herein can be performed by the base station 102 and the UE 104, and that reference to the base station and the UE in a generic manner is merely for convenience. Also, for each of the described flows, in the embodiments, the steps are performed in the order set forth in the language. In other embodiments, the steps are performed in a different order.

To help illustrate various embodiments of the present disclosure, a general description of a handover scheme used in the implementation of system 100 will now be described. However, other embodiments are possible.

Turning to fig. 3, a non-roaming architecture for interworking between an LTE data network and an NR data network will now be described. Functions (each of which is represented by a functional block that can be implemented as a computing device executing software to perform the function) are shown in the architecture.

The AMF performs the following operations: registration management, connection management, reachability management, and mobility management. The AMF also performs access authentication and access authorization. The AMF is a NAS security terminal, and relays an SM NAS between the UE and the SMF or the like.

The SMF performs the following operations: session management (e.g., session establishment, modification, and release), UE IP address assignment and management (including optional grants), selection and control of UP functions, downlink data notification, and the like.

The UPF performs the following operations: serving as an anchor for intra-RAT/inter-RAT mobility, packet routing and forwarding, traffic usage reporting, QoS handling for the user plane, downlink packet buffering, and downlink data notification triggering, etc.

The PCF performs the following operations: supporting a unified policy framework for managing network behavior, providing policy rules to one or more CP functions to enforce them, enforcing a front-end to access subscription information related to policy decisions in UDRs.

The functional blocks of fig. 3 that support EPS operation are as follows:

the MME performs the following operations: NAS signaling, NAS signaling security, inter-CN node signaling for mobility between 3GPP access networks (termination S3), UE reachability in ECM-IDLE state (including paging retransmission and optionally control, enforcement of paging policy differentiation), tracking area list management, PDN GW and serving GW selection, MME selection for handover with MME change, authentication, authorization, bearer management functions including dedicated bearer establishment, UE reachability procedures, etc.

The S-GW is a gateway that terminates the user plane interface towards the E-UTRAN.

The function of PGW-C is similar to that of SMF.

The function of the PGW-U is similar to that of the UPF.

The function of the PCRF is similar to that of the PCF.

To support interworking between 5GS and EPC/E-UTRAN, SMF and PGW-C, PCF are combined (e.g., performed by a single computing device) with PCRF, UPF and PGW-U.

According to an embodiment, a method for supporting handover from a first RAT network to a second RAT network involves a way of mapping a QoS model used in LTE to a QoS model used by an NR network. To provide context, the QoS model used in EPS will now be described.

The EPS provides connectivity between the UE and the PLMN external packet data network. This is called PDN connectivity service. PDN connectivity services are provided by EPS bearers. The EPS bearer uniquely identifies the traffic flow receiving the common QoS treatment between the UE and the PDN GW. The packet filters signaled in the NAS flow are associated with unique packet filter identifiers on a per PDN connection basis.

EPS bearer is a typical level of granularity for bearer level QoS control in EPC/E-UTRAN. That is, all traffic mapped to the same EPS bearer receives the same bearer level packet forwarding processing (e.g., scheduling policy, queue management policy, rate shaping policy, RLC configuration, etc.). Providing different bearer level packet forwarding processes requires separate EPS bearers.

When a UE connects to a PDN, one EPS bearer is established and remains established throughout the lifetime of the PDN connection to provide the UE with an always-on IP connection to the PDN. This bearer is referred to as a default bearer. Any further EPS bearer established for the same PDN connection is referred to as dedicated bearer.

The EPS bearer TFT is the set of all packet filters associated with that EPS bearer. The UL TFT is a set of uplink packet filters in the TFT. The DL TFT is a set of downlink packet filters in the TFT. Each dedicated EPS bearer is associated with a TFT. The TFT may also be assigned to a default EPS bearer. The UE uses UL TFT to map traffic to EPS bearers in the uplink direction. The PGW-U maps traffic to EPS bearers in the downlink direction using DL TFTs.

For the UE, the order of the evaluated priorities of the packet filters that make up the UL TFT is signaled from the PGW to the UE as part of any suitable TFT operation.

Based on the uplink packet filters in the TFTs assigned to these EPS bearers, the UE routes the uplink packets to the different EPS bearers. The UE evaluates the match, first the uplink packet filter with the lowest evaluation priority index among all TFTs, and if no match is found, continues the evaluation of the uplink packet filter in the increasing order of its evaluation priority index. This flow is performed until a match is found or all uplink packet filters are evaluated. If a match is found, the uplink data packet is sent on the EPS bearer associated with the TFT of the matching uplink packet filter. If no match is found, the uplink data packet is sent via the EPS bearer to which no uplink packet filter has been assigned. The UE drops the uplink data packet if all EPS bearers (including the default EPS bearer for that PDN) have been allocated one or more uplink packet filters.

The initial bearer level QoS parameter values for the default bearer are allocated by the network based on subscription data (in E-UTRAN the MME sets these initial values based on subscription data retrieved from the HSS).

In E-UTRAN, the decision to establish or modify a dedicated bearer is made by the EPC, and bearer level QoS parameter values are assigned by the EPC.

An EPS bearer is referred to as a GBR bearer if dedicated network resources related to the GBR value associated with the EPS bearer are permanently allocated (e.g., by an admission control function in the evolved node B) at bearer establishment/modification. Otherwise, the EPS bearer is referred to as a non-GBR bearer.

The dedicated bearer may be a GBR or non-GBR bearer. The default bearer is a non-GBR bearer. For illustration, fig. 4 depicts two unicast EPS bearers.

The EPS bearer is implemented by the following elements:

in the UE, the UL TFT converges and maps the flow stream to an EPS bearing in the uplink direction;

in the PDN GW, the DL TFT maps the traffic flow aggregation onto one EPS bearer in the downlink direction;

the PDN GW routes downlink packets to different EPS bearers based on downlink packet filters in TFTs allocated to EPS bearers in the PDN connection. Upon reception of a downlink data packet, the PDN GW evaluates the match, first the downlink packet filter with the lowest evaluation priority index, and if no match is found, continues the evaluation of the downlink packet filters in the increasing order of their evaluation priority indexes. This procedure is performed until a match is found, in which case the downlink data packet will be tunneled (tunneled) to the serving GW on the EPS bearer associated with the TFT of the matching downlink packet filter. If no match is found, the downlink data packet is sent via the EPS bearer without any TFT allocated. If all EPS bearers (including the default EPS bearer for that PDN) have already been allocated TFTs, the PDN GW will drop the downlink data packet.

The EPS bearer QoS profile includes parameters QCI, ARP, GBR and MBR. The QoS parameters applied to the aggregation set of EPS bearers include: APN AMBR and UE AMBR.

Each EPS bearer (GBR and Non-GBR) is associated with the following bearer level QoS parameters: QCI and ARP.

QCI is a scalar that is used as a reference for access node specific parameters that control bearer level packet forwarding processing (e.g., scheduling weights, admission thresholds, queue management thresholds, link layer protocol configurations, etc.), as well as those pre-configured by the operator owning the access node (e.g., evolved node B).

ARP contains information about the priority level (scalar), preemption capability (flag), and preemption vulnerability (flag). The main purpose of ARP is to decide whether a bearer establishment/modification request can be accepted or needs to be rejected due to resource limitations (typically the available radio capacity for GBR bearers). The ARP is not included in the EPS QoS profile sent to the UE.

Each GBR bearer is additionally associated with the following bearer level QoS parameters: GBR and MBR.

GBR denotes the bit rate that can be expected to be provided by a GBR bearer. MBR limits the bit rate that can be expected to be provided by the GBR bearer (e.g., excess traffic may be dropped by the rate shaping function).

In the EPS, the PCRF formulates PCC rules for the SDF. The PCC rules for QoS control are shown below in table 2:

TABLE 2

When PCRF provides PCC rule to PGW-C, PGW-C executes load binding as follows: the PGW-C evaluates whether one of the existing bearers can be used and whether a bearer modification (if applicable) can be initiated. And if the existing bearers can not be used, the PGW-C initiates the establishment of the proper bearer. A binding is created between one or more service data flows and bearers having the same QCI and ARP.

After binding, one or more packet filters in the service data flow template of the PCC rule are integrated into the TFT of the bearer to which the PCC rule is bound. PGW-C will assign a packet filter identifier and priority to each packet filter. For the bearer being a GBR bearer, the P-GW sets new values for GBR and MBR by accumulating the values of GBR and MBR of the PCC rule into the bearer. The new TFT is signaled to the UE along with the bearer identifier, QCI, and GBR/MBR (for GBR bearers).

The bearer context related to the QoS control sent to the UE is described in table 3 below:

TABLE 3

Additionally, fig. 5 shows the format of the TFT information element, and fig. 6 shows the format of the packet filter list when the TFT operation is "create new TFT", "add packet filter to existing TFT", or "replace packet filter in existing TFT".

To provide further context, the QoS model used in 5GS will now be described.

The 5G QoS model supports a framework based on QoS flows. The 5G QoS model supports QoS flows that require a guaranteed stream bit rate and QoS flows that do not require a guaranteed stream bit rate.

QoS flows are the best granularity of QoS differentiation in a PDU session. QFI is used to identify QoS flows in 5G systems. User-plane traffic with the same QFI in a PDU session receives the same traffic forwarding handling (e.g., scheduling, admission threshold). QFI is carried in the package header on N3 (and N9), i.e., no changes are made to the e2e packet header. It can be applied to PDUs with different types of payload, i.e. IP packets, unstructured PDUs and ethernet frames. QFI is unique within a PDU session.

Each QoS flow in the 5GS (GBR and Non-GBR) is associated with the following QoS parameters: 5QI and ARP.

Each GBR QoS flow is associated with the following additional QoS parameters: GFBR (UL and DL), MFBR (UL and DL), and notification control.

Two ways of controlling QoS flows are supported:

1) for non-GBR QoS flows with standardized 5QI, a 5QI value is used as QFI and default ARP is used. In this case, no additional N2 signaling is needed at the beginning of the traffic for the corresponding QoS flow;

2) for both GBR and non-GBR QoS flows, all necessary QoS parameters corresponding to QFI are sent as QoS profiles to the (R) AN, UPF at PDU session establishment or QoS flow establishment/modification.

At PDU session or at QoS flow setup, and each time NG-RAN is used when the user plane is activated, the QoS parameters for the QoS flow are provided as QoS profile to the (R) AN at N2. QoS parameters may also be preconfigured in the (R) AN for non-GBR QoS flows (i.e., not need to be signaled through N2).

The UE performs classification and marking of UL user plane traffic, i.e. association of uplink traffic with QoS flows, based on QoS rules. These rules may be explicitly signaled at N1 (at PDU session setup or QoS flow setup), pre-configured in the UE or implicitly derived by the UE from reflected QoS. The QoS rule contains a QoS rule identifier, a QFI for the QoS flow, one or more packet filters, and a priority value. More than one QoS rule may be associated with the same QFI (i.e., with the same QoS flow).

Each PDU session requires default QoS rules. The default QoS rule is the only QoS rule in a PDU session that may not contain a packet filter (in which case the highest priority value (i.e., lowest priority) needs to be used). If the default QoS rule does not contain a packet filter, the default QoS rule defines the handling of packets that do not match any other QoS rule in the PDU session.

The SMF allocates a QFI to each QoS flow and derives its QoS parameters from the information provided by the PCF. When applicable, the SMF provides the QFI along with the QoS profile containing QoS parameters for the QoS flow to the (R) AN. The SMF provides the UPF with the SDF template (i.e., the set of packet filters associated with the SDF received from the PCF) along with the SDF priority and corresponding QFI to enable classification and labeling of user plane traffic. When applicable, the SMF generates one or more QoS rules for the PDU session by allocating a QoS rule identifier, adding the QFI for the QoS flow, setting one or more packet filters to the UL portion of the SDF template, and setting the QoS rule priority to the SDF priority. The QoS rules are then provided to the UE to enable classification and tagging of UL user plane traffic.

The general principles for classifying and marking user plane traffic and mapping QoS flows to AN resources are illustrated in fig. 7.

In DL, incoming data packets are classified according to their SDF priority based on the SDF template (without initiating further N4 signaling). The CN uses QFI to convey the classification of user plane traffic belonging to QoS flows through N3 (and N9) user plane labels. The AN binds QoS flows to AN resources (i.e., data radio bearers in the case of a 3GPP RAN).

In the UL, the UE evaluates UL packets against packet filters in the QoS rules in increasing order based on the priority values of the QoS rules until a matching QoS rule is found (i.e., its packet filter matches the UL packet). The UE binds the UL packets to the QoS flow using QFI in the corresponding matching QoS rule. The UE binds the QoS flow to the AN resources.

If no match is found and the default QoS rule contains one or more uplink packet filters, the UE drops the uplink data packet.

The following characteristics apply to the processing of (application for) DL traffic:

UPF mapping user plane traffic to QoS flows based on SDF templates

The UPF sends the PDUs of the PDU session in a single tunnel between the 5GC and the (R) AN, the UPF including the QFI in the encapsulation header.

- (R) AN maps PDUs from the QoS flow to access specific resources based on QFI and associated 5G QoS characteristics and parameters, also taking into account the N3 tunnel associated with the downlink packets.

The following characteristics apply to the handling of UL traffic:

-the UE using the stored QoS rules to determine a mapping between UL user plane traffic and QoS flows. The UE transmits UL PDUs using the corresponding access-specific resources for the QoS flows based on the mapping provided by the RAN.

- (R) AN sends the PDU through AN N3 tunnel to the UPF. When AN UL packet is delivered from the (R) AN to the CN, the (R) AN determines the QFI value (which is included in the encapsulation header of the UL PDU) and selects the N3 tunnel.

The 5QI is a scalar (e.g., scheduling weights, admission thresholds, queue management thresholds, link layer protocol configuration, etc.) that is used as a reference to the 5G QoS characteristics, i.e., access node specific parameters that control the QoS forwarding process for the QoS flow.

The 5QI within the range of standardized values has a one-to-one mapping with a standardized combination of 5G QoS characteristics.

For non-standardized combinations of 5G QoS characteristics, 5QI values from non-standardized value ranges are signaled along with 5G QoS characteristics through N2, N11, and N7 at PDU session or QoS flow setup.

For GBR QoS flows, the 5G QoS profile additionally includes the following QoS parameters: GFBR (UL and DL) and MFBR (UL and DL).

GFBR represents the bit rate that can be expected to be provided by a GBR QoS stream. The MFBR limits the bit rate that can be expected to be provided by the GBR QoS flow (e.g., excess traffic may be dropped by the rate shaping function).

For each of the GBR QoS flows, a GFBR and an MFBR are signaled over N2, N11, and N7 to set up a 5G QoS profile.

Based on the information received from the PCF, the MBR of each SDF is signaled on N7 and N4.

In 5GS, the PCF formulates PCC rules for Service Data Flows (SDFs). PCC rules for QoS control may be defined as shown in table 4 below:

TABLE 4

When the PCF provides PCC rules to the SMF, the SMF performs QoS flow binding in a similar manner to the bearer binding procedure described above, with the following differences:

bearer replacement by QoS flow

-creating a binding between one or more service data flows and QoS flows having at least the same 5QI and ARP.

After binding, the QoS rules are derived based on the PCC rules and may be defined in the 5GS, as shown in table 5 below:

TABLE 5

If the bearer is a GBR bearer, the P-GW sets the new values of GBR and MBR by accumulating the values of GBR and MBR of the PCC rule into the bearer. The new TFT is signaled to the UE along with the bearer identifier, QCI, and GBR/MBR (for GBR bearers).

From the above analysis, the QoS information received by the UE in the EPS is different from the QoS information received by the UE in the 5 GS. If the UE has created the default bearer and the dedicated bearer in the EPS, the UE switches from the EPS to the 5GS, and the UE does not know the current QoS information in the 5GS corresponding to the QoS information in the EPS during/after the switch. The user experience will be affected before the QoS information is updated in the 5 GS.

According to an embodiment, when the UE performs handover from the EPS data network (e.g. LTE) to the 5GS, both the UE and the network (e.g. SMF) derive the QFI based on the EPS bearer id according to the same logic. The value of QFI is reserved for the specific use of the mapped form of EPS bearer id.

In an embodiment, the UE and the network (e.g., SMF) derive the QoS rule identifier based on the packet filter identifier or the EPS bearer id and the packet filter identifier.

According to an embodiment, for each QoS flow (i.e. EPS bearer), the SMF provides a QoS profile comprising a combination of QFI, ARP and 5 QI/resource type, priority level, PDB and PER to the NR. The QoS profile may additionally include GBR and MBR for the QoS flow.

An example EPS attach procedure according to an embodiment will now be described with reference to fig. 8.

UE 802 initiates an attach procedure to eNodeB804 by sending an attach request including IMSI or old GUTI, attach type, APN, etc.

eNodeB804 derives the MME address and forwards the attach request message to MME 806.

MME806 determines that it is an initial attach, and MME806 then allocates an EPS bearer identity (i.e., EPS bearer id1, e.g., EPS bearer id1 value of 5) for the default bearer associated with UE 802. The MME806 selects PGW-C according to the APN. And then the MME806 selects the SGW. The MME806 sends a create session request to the SGW 808 including the IMSI, APN, PGW-C address, etc.

SGW 808 creates a new entry in its EPS bearer table and sends a create session request (IMSI, APN, serving GW address of user plane, serving GW TEID of control plane, EPS bearer identity, etc.) message to PGW-C indicated by PGW-C address received in the previous step.

5. If a dynamic PCC is deployed, PGW-C810 performs an IP-CAN session establishment procedure by sending an IP-CAN session establishment request that includes the IMSI, APN, and UE IP address, etc.

PCRF 814 makes policy decisions and provides UE 802 with default PCC rules and EPS bearer QoS in a response message (i.e., EPS bearer QoS 1. this EPS bearer QoS is typically referred to as default EPS bearer QoS). The default PCC rules include PCC rule id (i.e., PCC rule id1), SDF template (i.e., packet filter 1 is a packet filter that matches all traffic), QCI (i.e., QCI1), and ARP (ARP 1). PCRF 814 also provides PGW-C810 to the APN-AMBR. All matching packet filters allow all traffic of the PDN connection to pass through. EPS bearer QoS1 includes QCI (i.e., QCI1) and ARP (i.e., ARP 1). In this flow, the values of QCI and ARP of the default PCC rule are equal to the values of QCI and ARP of the default EPS bearer.

PGW-C810 creates an EPS bearer context table for the default bearer. The PGW-C810 creates a PDR according to the PCC rules and provides the PDN connection to the PGW-U. The PGW-C810 also provides the PGW-C810 with the serving GW address of the user plane, the serving GW TEID of the user plane. The PGW-U installs the PDR and applies control to the traffic of the PDN connection.

The PGW-U812 sends a response message to the PGW-C810.

PGW-C810 returns create session response (PDN GW address of user plane, PDN GWTEID of user plane, PDN GW TEID of control plane, PDN address, EPS bearer identity, EPS bearer QoS, APN-AMBR, etc.) message sent to serving GW.

10. The serving GW returns a create session response (PDN address, serving GW address for user plane, serving GW TEID for S1-U user plane, serving GW TEID for control plane, EPS bearer identity, EPS bearer QoS, TEID and PDN GW address at PDN GW for uplink traffic, protocol configuration options, prohibit payload compression, APN restriction, cause, MS information change reporting action (start), presence reporting area action, CSG information reporting action (start), APN-AMBR, delay tolerant connection) message to MME 806.

MME806 sends Attach Accept (GUTI, TAI list, session management request (APN, PDN type, PDN address, EPS bearer identity), etc.) message (Attach Accept message) to eNodeB 804. This message is included in the S1_ MME control message initial context setup request. The S1-AP initial context setup request message further includes AS security context information for the UE, EPS bearer QoS, UE-AMBR, EPS bearer identity, and TEID at serving GW for user plane and address of serving GW for user plane.

The eNodeB804 sends an RRC connection reconfiguration message including an EPS radio bearer identity to the UE 802 and sends an attach accept message to the UE 802 together.

The UE 802 sends an RRC connection reconfiguration complete message to the eNodeB 804.

eNodeB804 sends an initial context response message to MME 806. The initial context response message includes the address of eNodeB804 and the TEID of eNodeB804 for downlink traffic on the S1_ U reference point.

The UE 802 sends a direct transfer message to the eNodeB804, the direct transfer message including an Attach Complete (EPS bearer identity, etc.) message (Attach Complete message).

eNodeB804 forwards the attach complete message to MME806 in an uplink NAS transport message.

17. Upon receiving both the initial context response message and the attach complete message, the MME806 sends a modify bearer request (EPS bearer identity, eNodeB address, eNodeB TEID, etc.) message to the serving GW.

18. The serving GW replies by sending a modify bearer response (EPS bearer identity) message to the MME 806. The serving GW may then send its buffered downlink packets.

Since the values of QCI and ARP of the default PCC rule are equal to the values of QCI and ARP of the default EPS bearer, the default PCC rule is bound to the default bearer according to the binding mechanism. Furthermore, the packet filters of the default PCC rule are all matching packet filters, so there is no need to send the packet filters to the UE. (a default bearer without a TFT means that any traffic of the PDN connection can be transported via the default bearer).

In this example, the context of QoS control related to the default bearer in the UE is as shown in table 6 below:

EPS bearer Id	5
		TFT-none	Is free of
EPS bearing QoS	QCI1，ARP1

TABLE 6

Now, for this example, the context of QoS control in PGW-C related to the default bearer is as shown in table 7 below:

EPS bearer Id	5
		TFT-none	Is free of
EPS bearing QoS	QCI1,ARP1

TABLE 7

An example dedicated EPS bearer activation procedure according to an embodiment will now be described with reference to fig. 9.

1. If a dynamic PCC is deployed, PCRF 914 formulates and sends a new PCC rule (i.e., PCC rule 2) to PGW-C910. The PCC rules include PCC rule id (i.e., PCC rule id2), SDF templates (i.e., packet filter 2 and packet filter 3), priority, QCI (i.e., QCI2), ARP (ARP2), GBR, and MBR. The PCRF may make this decision based on a trigger from the UE, the external network, or internal logic of the PCRF. The UE may provide the packet filter and requested QoS if it decides based on a trigger for the UE. Based on the request from the UE, the PCRF provides PCC rules 2 to the PGW-C.

PGW-C910 stores the new PCC rules and sends a response message to PCRF 914.

PGW-C910 performs bearer binding. Since the QCI and ARP of the new PCC rules are different from the default bearer, PGW-C910 decides to create a new bearer. The PGW-C910 sends a create bearer request message (IMSI, EPS bearer QoS, TFT, S5/S8 TEID, LBI, etc.) to the serving GW (LBI is EPS bearer identity of the default bearer). EPS bearer QoS includes QCI (i.e., QCI2), ARP (ARP2), GBR, and MBR. The TFT includes two packet filters (i.e., a packet filter 2 and a packet filter 3). Each packet filter has its packet filter id and priority assigned by the PGW-C910.

SGW 908 sends create bearer request (IMSI, EPS bearer QoS, TFT, S1-TEID, PDN GW TEID, LBI, etc.) message to MME 906.

MME906 selects an EPS bearer identity (i.e., EPS bearer id2, with a value of 6) that has not yet been assigned to UE 902. MME906 then builds a session management request that includes TFT, EPS bearer QoS parameters (not including ARP), EPS bearer identification, and LBI. MME906 then signals a bearer setup request (EPS bearer identity, EPS bearer QoS, session management request, S1-TEID) message to eNodeB 904.

eNodeB 904 maps EPS bearer QoS to radio bearer QoS. It then signals an RRC connection reconfiguration (radio bearer QoS, session management request, EPS RB identity) message to the UE 902. The UE 902NAS stores the EPS bearer identity and links the dedicated bearer to the default bearer indicated by the LBI. The UE 902 uses an uplink packet filter (ULTFT) to determine a mapping of traffic flows to radio bearers.

The UE 902 acknowledges the radio bearer activation to the eNodeB 904 with an RRC connection reconfiguration complete message.

eNodeB 904 acknowledges the bearer activation to MME906 with a bearer setup response (EPS bearer identity, S1-TEID) message.

The UE 902NAS layer constructs a session management response including the EPS bearer identity. The UE then sends a direct transfer (session management response) message to the eNodeB.

eNodeB 904 sends an uplink NAS transport (session management response) message to MME 906.

11. Upon receiving the bearer setup response message and the session management response message, the MME906 acknowledges the bearer activation to the serving GW by sending a create bearer response (EPS bearer identity, S1-TEID) message.

12. The serving GW 908 acknowledges the bearer activation to the PGW-C910 by sending a create bearer response (EPS bearer identity, S5/S8-TEID) message.

PGW-C910 makes a new PDR based on the new PCC rules and provides it to PGW-U912. PGW-C910 also provides S5/S8-TEID to PGW-U912. The PGW-U installs the new PDR and applies control to the traffic matching packet filter 2 and packet filter 3.

Now, for this example, the context of bearer-related QoS control in the UE 902 is as shown in table 8 below:

TABLE 8

The UE or network may also modify the established dedicated bearer discussed above after the dedicated bearer modification procedure by providing the EPS bearer id, e.g., according to current prior art.

An example handover procedure from EPS to 5GS according to an embodiment will now be described with reference to fig. 10.

1. The source RAN 1004 (e.g., LTE RAN) decides that the UE 1002 should be handed over to the target RAN1006 (e.g., 5 GRAN). The source RAN 1004 sends a handover required (target RAN node ID, source to target transparent container) message to the MME 1008.

MME 1008 selects a target AMF and sends a forward relocation request (target RAN node ID, source-to-target transparent container, EPS MM context, EPS bearer context (s)) message to the selected AMF 1010.

AMF 1010 sends a PDU switch request (PDN connection, AMF ID) message to the selected SMF (SMF as part of block 1014). The PDN connection provides the address of the combined SMF + PGW-C1014.

4. If dynamic PCC is deployed, SMF may initiate a PDU-CAN session modification to PCF + PCRF 1018 to obtain the 5GS PCC rules for the PDU session. PCF + PCRF 1018 does not apply to the 5GS PCC rules for PDU sessions.

5. Since the SMF + PGW-C1014 is aware of the handover event, the SMF + PGW-C1014 modifies the UPF + PGW-U1016 by providing a new PDR.

SMF + PGW-C1014 converts the stored EPS bearer context to a 5GS PDU flow context using at least the following techniques:

(1) the SMF + PGW-C1014 derives each QFI based on the EPS bearer id according to an algorithm. The range of QFI is reserved for specific use of id mapping from EPS bearers. For example, if the QFI is encoded in one octet length, i.e., the value is from 0-255, then the values 128-255 may be reserved for this purpose. And currently, the EPS bearer id is encoded into 4 bits. Thus, SMF + PGW-C1014 derives QFI as follows: QFI EPS bearer id + 128.

(2) The SMF + PGW-C1014 derives each QoS rule id according to another algorithm based on the packet filter id or EPS bearer id and the packet filter id. And currently, the EPS bearer id is encoded as 4 bits and the packet filter id is encoded as 4 bits. And reserving the value of 1-4 for the EPS bearing id. If SMF + PGW-C derives each QoS rule id based on the packet filter id only, one possible algorithm is that the QoS rule id is equal to the packet filter id. If the SMF + PGW-C1014 derives each QoS rule id based on the EPS bearer id and the packet filter id, one possible algorithm for the SMF + PGW-C1014 to derive the QoS rule id may be the result of the concatenation of the EPS bearer id with the packet filter id, as shown in fig. 11.

For a default EPS bearer without TFT, the packet filter id part may be set to any value.

According to an embodiment, the QoS rules mapped from the EPS bearer context by the SMF + PGW-C1014 are as shown in table 9 below:

TABLE 9

According to an embodiment, the QoS profile derived by SMF + PGW-C1014 is as shown in table 10 below:

watch 10

SMF + PGW-C1014 sends a PDU session modification response (PDU session ID, authorized QoS profile (QoS profile 1(QFI (133), QoS parameters (QCI1, ARP1)), QoS profile 2(QFI (134), QoS parameters (QCI2, ARP2, GBR, MRR)), EPS bearer setup list, SSC mode, CN tunnel information) to AMF 1010.

AMF 1010 sends a handover request (source to target transparent container, N2 SM info (PDU session ID, QoS profile, CN tunnel info)) message to target RAN 1006.

8. The target RAN1006 sends a handover request acknowledgement (target to source transparent container, N2 SM information for PDU forwarding (PDU session ID, N3 tunnel information for PDU forwarding)) message to the AMF 1010.

The AMF 1010 sends a modify PDU session request (N2 SM info for PDU forwarding (PDU session ID, N3 tunnel info for PDU forwarding)) message to the SMF to update the N3 tunnel information.

SMF + PGW-C1014 sends to AMF 1010: modify PDU response (PDU session ID, EPS bearer setup list).

AMF 1010 sends a message forwarding relocation response (cause, target to source transparent container, serving GW change indication, EPS bearer setup list, AMF tunnel endpoint identifier for control plane, address and TEID).

MME 1008 sends a handover command (target to source transparent container, bearer subject to forwarding, bearer to release) message to the source RAN. The bearer subject to forwarding includes an address list allocated for forwarding and CN tunnel information. The bearer to be released comprises a list of bearers to be released.

13. The source RAN 1004 sends a command to the UE 1002 to cause the UE 1002 to handover to the target RAN 1006. The UE 1002 moves and synchronizes to the target RAN1006 from the source RAN 1004.

14. Switching confirmation: the UE 1002 acknowledges the handover to the target RAN 1006. In an embodiment, as shown in table 11, the UE 1002 converts the EPS bearer context to QoS rules as performed by the SMF.

15. And switching notification: the target RAN1006 informs the AMF 1010 that the UE 1002 is handed over to the target RAN 1006. The notification message includes N2 SM information (N3 DL tunnel information).

16. Then, the AMF 1010 knows that the UE 1002 has reached the target side, and notifies the MME 1008 by sending a Forward Relocation Complete Notification Message (Forward Relocation Complete Notification Message). The MME responds with a forward relocation complete notification response message.

AMF 1010 sends SMF + PGW-C1014 the following: handover is complete (PDU session ID). Each PDU session sends a handover completion to the corresponding PGW-C + SMF to indicate that the N2 handover was successful.

The SMF + PGW-C1014 updates the UPF + PGW-U1016 with CN tunnel information, and the SMF + PGW-C provides the updated PDR to the UPF + PGW-U.

19. If the PCC infrastructure is used, SMF + PGW-C1014 informs the home-PCF + home-PCRF that changes (created in step 6 of the preparation phase) in respect of, for example, RAT type and 5GS PCC rules should become active from this point on.

SMF + PGW-C1014 sends the following to AMF 1010: handover complete acknowledgement (PDU session ID).

SMF + PGW-C indicates to the selected UPF: the downlink user plane for the indicated PDU session may be handed over to the target RAN 1006. SMF + PGW-C1014 acknowledges receipt of the handover complete.

UE 1002 registers in target 5GS with "mobility registration update".

22. Resources in the source system and resources for PDU forwarding are released by the MME 1008.

During the handover procedure, UE 1002 and SMF + PGW-C1014 translate the EPS bearer context into QoS rules. Then, the UE 1002 and the network perform QoS control based on the derived QoS information in the 5 GS. The UPF + PGW-U applies control to downlink traffic according to the updated PDR, including: (a) set the QFI value to 134 in the encapsulation header for the traffic, which matches packet filter content 1 and packet filter content 2, and (b) set the QFI value to 133 in the encapsulation header for the other traffic. The UE applies control to uplink traffic according to QoS rules, including: (a) set the QFI value to 134 in the encapsulation header for the traffic, which matches packet filter content 1 and packet filter content 2, and (b) set the QFI value to 133 in the encapsulation header for the other traffic.

The UE and the network may also update or remove the derived QoS rules.

An example PDU session modification procedure in PCF triggered 5GS will now be described with reference to fig. 12, in accordance with an embodiment.

The PCF (of PCF + PCRF 1212) sends a PDU-CAN modification request message to SMF + PGW-C1208 to remove PCC rule 2. The PCF may make this decision based on a trigger from the UE, an external network, or internal logic of the PCF. The UE may request to remove the QoS rules if a decision is made using a trigger from the UE. In this case, the UE provides the QoS rule id (i.e., 96 and 97 if the UE derives the QoS rule id based on the EPS bearer id and the packet filter id; and 0 and 1 if the UE derives the QoS rule id based on the packet filter id only). If the UE provides 0 and 1, the UE provides QFI together (i.e., 134). Based on the request from the UE, the PCF removes PCC rule 2.

SMF remove PCC rule 2 (of SMF + PGW-C1208). Since PCC rule 2 corresponds to QoS rules having QoS rule IDs of 96 and 97, the SMF decides to remove QoS rules having QoS rule IDs of 96 and 97, and the SMF sends an SM request (N2 SM information (PDU session ID, remove QoS flow (QFI (1340)), session-AMBR), N1 SM container (PDU session modification order (PDU session ID, remove QoS rule with QoS rule ID (96 and 97)), session-AMBR))) message to AMF 1206. The N2 SM information carries the information that the AMF provides to the (R) AN. The N1 SM container carries the PDU session modification command that the AMF provides to the UE.

AMF 1206 may send AN N2 PDU Session request (N2 SM info, NAS message received from SMF) message to the target (R) AN.

4. The target (R) AN 1204 may issue AN-specific signaling exchange with the UE related to information received from the SMF. (R) the AN releases resources for the QoS flow using QFI (134). The UE removes the QoS rule with QoS rule id (96 and 97). The UE acknowledges the PDU session modify command by sending a PDU session modify command acknowledge message via NAS SM signaling.

5. The target (R) RAN may acknowledge the N2 PDU session request by sending an N2 PDU session release acknowledge (NAS message, user location information) message to AMF 1206.

AMF 1206 forwards the N2 PDU session release acknowledgement (including NAS message) received from the AN to the SMF via the SM request acknowledgement.

The SMF may update the N4 session of the one or more UPFs involved in PDU session modification by sending an N4 session modification request (N4 session ID) message to the UPF (of the UPF + PGW-U block 1210).

According to an embodiment, the UE or the network may also follow the flow set forth in fig. 12 in order to modify the QoS rules. In this case, the new QFI requested may also be included in the request.

Turning to fig. 13, an example of how a UE may map QoS from a 4G network to a 5G network, such as during handover between two RATs, will now be described. In this embodiment, the handover procedure from 4G to 5G will have Nx support. In this example, the mapping is local to the UE. The row labeled "equal" means that the 5G parameter is the same as the 4G parameter. The other rows indicate that the 5G parameters are derived from the 4G parameters. The annotations mentioned in fig. 13 are as follows:

note 1: one consideration is how many PDN connections a UE has under the same APN during a 4G to 5G handover. For example, if there are two PDN connections under the same APN, the APN-AMBR is 10M bits. This means that the two PDN connections share bandwidth. There are various ways in which a UE can share bandwidth between two PDN connections.

In an embodiment, the session AMBR is equal to the APN-AMBR.

Note 2: the concept of SSC pattern does not exist in 4G systems. In many cases, the 4G session model is the same as SSC pattern 1 in the 5G system.

To simplify processing the SSC pattern 2/3 according to an embodiment: (1) the inability to switch SSC pattern 2/3PDU sessions to 4G; or (2) the SSC pattern 2/3PDU session may be switched to 4G. For PDU session handover from 4G (PDN connection), the SSC pattern will be 1.

Note 3: for 4G to 5G switching, the QFI value space is reserved (e.g., 128-. And the QFI value space does not overlap with the normalized QFI value.

Note 4: there is a Packet Filter (PF) in the TFT of each bearer. Each PF is a triplet including packet filter contents, packet filter id (PF id), priority. In an embodiment, the mapping rules are as follows:

(1) each Packet Filter (PF) will be mapped to a Qos rule;

(2) and setting the Qos rule ID as PF ID or EBI | | | PF ID. In 4G, EBI is 4 bits and PF ID is 4 bits. Thus, the EBI combines the PF ID, which creates a unique 8-bit value in the PDU session.

(2) (a) for example, EBI is 0101, PF ID is 0011, so Qos rule ID is 01010011.

(2) (b) another case is the absence of a packet filter in the default bearer in 4G. The Qos rule ID is set to EBI | | 0000. For example, the default EBI is 0101, no packet exists. The mapped Qos rule ID is 01010000.

(3) The packet filter content in 5G is directly set to 4G PF content.

(4) So far, no PF ID exists in 5G. If it is already defined, it can be derived from the 4G PF id.

According to an embodiment, the UE maps the 4G parameters locally to the 5G Qos parameters. The UE or SMF may initiate PDU session modification or QoS rule modification/removal if needed.

It is to be understood that the embodiments described herein are to be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects in each embodiment should typically be considered as available for other similar features or aspects in other embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope thereof. For example, the steps of the methods described herein may be reordered in a manner apparent to those skilled in the art.

Claims

1.A method for facilitating handover of a user equipment from a first network using a first radio access network to a second network using a second radio access network, the method comprising:

receiving a context for a connection of the user equipment via the first network, wherein the context comprises a bearer identifier of the connection;

deriving a quality of service flow identifier from the bearer identifier; and is

Transmitting the quality of service flow identifier to the second network.

2. The method of claim 1, wherein deriving the quality of service flow identifier comprises: mapping the bearer identifier to a particular range of the quality of service flow identifier.

3. The method of claim 2, wherein mapping the bearer identifier to a particular range of the quality of service flow identifier comprises: adding a constant to the bearer identifier.

4. The method of claim 1, wherein transmitting the quality of service flow identifier to the second network comprises: the quality of service flow identifier is sent as part of a packet data unit session modification procedure or is set on an encapsulation of uplink traffic.

5. The method of claim 1, wherein the context comprises a packet filter identifier, the method further comprising:

deriving a quality of service rule identifier from the packet filter identifier; and is

Sending the quality of service rule identifier to the second network.

6. The method of claim 5, wherein deriving the quality of service rule identifier comprises combining the bearer identifier with the packet filter identifier.

7. The method of claim 5, wherein transmitting the quality of service rule identifier to the second network comprises: the quality of service rule identifier is sent as part of a packet data unit session modification procedure.

8. A method for facilitating handover of a user equipment from a first network using a first radio access network to a second network using a second radio access network, the method comprising:

sending a context for a connection to the user equipment via the first network, wherein the context comprises a bearer identifier of the connection;

Transmitting the quality of service flow identifier to the user equipment via the second network.

9. The method of claim 8, wherein deriving the quality of service flow identifier comprises: mapping the bearer identifier to a particular range of the quality of service flow identifier.

10. The method of claim 9, wherein mapping the bearer identifier to a particular range of the quality of service flow identifier comprises: adding a constant to the bearer identifier.

11. The method of claim 8, wherein transmitting the quality of service flow identifier to the user equipment via the second network comprises: the quality of service flow identifier is sent as part of a packet data unit session modification procedure.

12. The method of claim 11, wherein the context comprises a packet filter identifier, the method further comprising:

Transmitting the quality of service rule identifier to the user equipment via the second network.

13. The method of claim 12, wherein deriving the quality of service rule identifier comprises combining the bearer identifier with the packet filter identifier.

14. The method of claim 12, sending the quality of service rule identifier to the user equipment via the second network comprises: the quality of service rule identifier is sent as part of a packet data unit session modification procedure.

15. The method of claim 8, wherein the user plane function is instructed to set the quality of service flow identifier on an encapsulation of downlink traffic.

16. The method of claim 11, wherein the quality of service flow identifier is transmitted to the second radio access network.

17.A computing device that executes any of claims 1-16.

18. A non-transitory computer-readable medium having stored thereon computer-executable instructions for performing the method of any one of claims 1-16.