WO2018085187A1 - Internetworking between next generation core and evolved packet core - Google Patents

Abstract

An apparatus of a NextGen user equipment (NG UE) comprises one or more baseband processors to decode a message indicating whether an N26 interface exists between a NextGen Core (NGC) and an Evolved Packet Core (EPC), and to initiate a mobility procedure with session continuity if the NG UE is to relocate from the NGC to the EPC, the mobility procedure being dependent on whether the N26 interface exists or not. The message may be stored in a memory.

Description

INTERNETWORKING BETWEEN NEXT GENERATION CORE AND EVOLVED PACKET

CORE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of US Provisional Application No.

62/417,589 (P111773Z) filed November 4, 2016 and the benefit of US Provisional Application No. 62/444,120 (P113290Z) filed January 9, 2017. Said Application No. 62/417,589 and said Application No. 62/444,120 are hereby incorporated herein by reference in their entireties.

BACKGROUND

[0002] The Third Generation Partnership Project (3GPP) is doing a feasibility study on the next generation system (FS_NextGen), also known as the Fifth Generation or 5G system. The NextGen system consists of a NextGen Radio Access Network (NG RAN) and a NextGen Core (NGC). It is expected that the NextGen system will initially deployed in islands. When a user equipment UE move out of the NextGen system coverage, it needs to fall back to the Evolved Packet System (EPS), also known as a Fourth Generation or 4G system.

[0003] One of the problems to solve is interworking between an NGC and an EPC so that the interruption time upon UE moving from one system to the other is minimized. At the same time, the impact on both the EPS and the NGS should be minimized. 3GPP TS 23.401 clause 5.3.2.1 defines the EPS Attach procedure that exists in two flavors: Initial Attach and Handover Attach. A basic Handover Attach procedure may be used to enable seamless handovers between NGC and EPC only if there is support for dual radio at the lower layers, that is concurrent receive and transmit (Rx/Tx) connections between the UE and the source and target radio during the transition or handover period. It is noted here that the term "Handover Attach" is a bit of a misnomer because the "handover indication" is included inside the PDN CONNECTIVITY REQUEST session management message that in EPS is embedded within the ATTACH REQUEST mobility management message. It should be noted that a seamless handover in 3GPP terms refers to a handover where the service break is lower than 300 milliseconds (ms). When there is no support for dual radio at the lower layers, the basic Handover Attach leads to a service break that is comparable to the duration of the Attach procedure. The actual value depends on many factors, but typical field test values range from 450 ms and up to about one or more seconds.

[0004] The basic Handover Attach procedure therefore cannot be used to provide seamless handovers, but it can still be used to provide handovers with session continuity. It is therefore not completely ruled out because it is expected that in some deployments there will be no need for support of seamless handovers, while session continuity will be a requirement. DESCRIPTION OF THE DRAWING FIGURES

[0005] Claimed subject matter is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, such subject matter may be understood by reference to the following detailed description when read with the accompanying drawings in which:

[0006] FIG. 1 is a diagram of an architecture of a network providing internetworking between a NextGen System (NGS) and an Evolved Packet System (EPS) with the an NGx (N26) interface in accordance with one or more embodiments;

[0007] FIG. 2 is a diagram of a default bearer handover and dedicated bearer reactivation after handover completion in accordance with one or more embodiments;

[0008] FIG. 3 is a diagram of a tracking area update procedure in accordance with one or more embodiments;

[0009] FIG. 4 illustrates an architecture of a system of a network in accordance with some embodiments;

[00010] FIG. 5 illustrates example components of a device in accordance with some embodiments; and

[00011 ] FIG. 6 illustrates example interfaces of baseband circuitry in accordance with some embodiments.

[00012] It will be appreciated that for simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements.

DETAILED DESCRIPTION

[00013] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of claimed subject matter. It will, however, be understood by those skilled in the art that claimed subject matter may be practiced without these specific details.

In other instances, well-known methods, procedures, components and/or circuits have not been described in detail.

[00014] Referring now to FIG. 1, a diagram of an architecture of a network providing internetworking between a NextGen System (NGS) and an Evolved Packet System (EPS) with the an NGx (N26) interface in accordance with one or more embodiments will be discussed. As shown in FIG. 1, network 100 may include a Home Subscriber Server (HSS) 110 (HSS + User Data Management (UDM) in 3 GPP TS 23.501) to couple to an Evolved Packet Core (EPC) 118 via an S6a interface and to couple to a NextGen (NG) Core 120 via NG S6a (N8 in 3 GPP TS 23.501) interface. The EPC 118 is able to provide wireless access for user equipment (UE) 130 and/or NG UE 132 to network 100 via radio access network (RAN) 128 which implement a Global System for Mobile Communication (GSM) Enhanced Data Rates for GSM Evolution (EDGE) Radio Access Network (GERAN), Universal Terrestrial Radio Access Network (UTRAN), or non- evolved Long-Term Evolution (LTE) access, or an Evolved-UTRRAN (E-UTRAN), for example via an Sl/Iu/Gb interface, although the scope of the claimed subject matter is not limited in this respect. Similarly, the NG Core 120 is able to provide wireless access for NG UE 136 to network 100 via NG RAN 124 via an NG2/NG3 (N2/N3 in 3 GPP TS 23.501) interface, although the scope of the claimed subject matter is not limited in this respect.

[00015] Furthermore, a packet gateway (PGW) 114 may include a Session Management Function (SMF)/Internet Protocol (IP) anchor 116 (SMF/UPF + PGW-C/PGW-U in 3 GPP TS 23.501) to couple to EPC 118 via an S5 interface, and to NG Core 120 via NG11/NG9 (N11/N3 in 3 GPP TS 23.501) interface, and also may couple to a PCRF/PCF 112 via a Gx and NG Gx (N15 in 3GPP TS 23.501) interface. In order to support a seamless handover between EPC 118 and NG Core 120, an NGx control plane interface 122 may be provided between EPC 118 and NG Core 120, which also may be referred to an N26 interface. In some deployments, however, the NGx (N26) interface 122 may not be present. In such scenarios, session continuity may still be supported when NG UE 136 moves between the Evolved Packet System (EPS) 124 and the NextGen System (NGS) 126. As discussed herein, the procedures executed by NG UE 126 when moving between EPS 124 and NGS 126 may be selected based on whether the NGx (N26) interface is supported in the network 100 or not. Such procedures may apply both to NG UE 126 in a CN_Connected mode or in a CN_Idle mode. In general, the direction of movement of NG UE 136 from NGS 126 to EPS 124 is described since the NGS system is still under development, although consideration is also provided herein for mobility in the opposite direction, and the scope of the claimed subject matter is not limited in this respect.

[00016] As will be discussed in further detail with respect to FIG. 2 below, if NGx (N26) interface 122 is supported on network 100, for a NG UE136 that was in CN_Connected mode in NGS 126, upon mobility to EPS 124, the procedure for a "Default bearer" handover and "dedicated bearer" reactivation may be performed. This procedure is a variation of the conventional handover procedure whereby only basic QoS service is provided in the target system upon completion of the handover procedure proper (this is the "Default bearer" handover part of the overall procedure), whereas full QoS service is restored in the target system in a second step (this is the "Dedicated bearer" reactivation part of the overall procedure). For a NG UE 136 that was in CN_Idle mode in NGS 126, upon mobility to EPS 124, a Tracking Area Update (TAU) may be performed. As will be discussed in further detail with respect to FIG. 3 below, if NGx (N26) interface 122 is not supported on network 100, the NG UE 136 may perform a Handover Attach procedure upon mobility to EPS 124 regardless of the state, the CN_Connected state or a CN_Idle state, of the NG UE 136 when it was on the NGS 126. If in the CN_Connected mode on NGS 126, the NG UE 136 is instructed by network 100 about the procedure to follow on the target side with an indication provided at access stratum, for example in the Radio Resource Control (RRC) Connection Release with Redirection procedure, or with an indication provided at non-access stratum, for example in the Registration Accept message during registration or re-registration with the NG Core 120. If in the CN_Idle mode on NGS 126, the NG UE 136 should be aware whether the NGx (N26) interface 122 is supported on the network 100 or not. Several ways may be defined for indicating to the NG UE 126 whether the NGx (N26) interface 126 is supported, which influences the NG UE 126 into deciding which procedure, TAU or Handover Attach, to use when reselecting to EPS 124. The solution for assisting the UE into deciding which Non- Access Stratum (NAS) procedure to use upon mobility from NGS 126 to EPS 124 depending on the presence or absence of NGx (N26) interface between the two systems is discussed in further detail, below.

[00017] Referring now to FIG. 2, a diagram of a default bearer handover and dedicated bearer reactivation after handover completion in accordance with one or more embodiments will be discussed. The process 200 shown in FIG. 2 may be implemented in the where network 100 of FIG. 1 supports the NGx (N26) interface 122. Process 200 may be directed the case of a single registered UE for a NG UE 136 that has only one mobility management (MM) state machine and is either operating in NG1 mode and connected to NGC 120 or in SI mode and connected to EPC 118. Similarly, network 100 keeps only one active MM state machine that is synchronized with the MM state machine in the NG UE 136 and is located in either the NG Core 120 or in the EPC 118 fir example in the Mobility Management Entity (MME). In such an arrangement, the NGx (N26) interface 122 may be used for MM context transfer as well as transfer of information for assisting seamless handovers. In one or more embodiments, the term handover may refer to a network-controlled mobility procedure for NG UE 136 in a connected state that involves some preparation in the target system ahead of the handover event, although the scope of the claimed subject matter is not limited in this respect.

[00018] When NG UE 136 is in CN_Connected mode on NGS 126, it is possible to use the procedure for "Default bearer handover and dedicated bearer re-activation" as shown in FIG. 2. Regarding Idle mode mobility for NG UE 136 that was in CN_Idle mode in NGS 126 before moving to EPS 124, an existing tracking area (TA) Update procedure as shown in and described with respect to FIG. 3, below, may be utilized. The NGx (N26) interface 122 in this case has the same functionality as a MME-MME interface referred to as an S 10 interface. In addition, mobility between EPS 124 and NGS 126 corresponds to a context transfer as illustrated in operations 4, 5, and 7 of FIG. 3, below.

[00019] As shown in FIG. 2, the NG UE 136 initially may be attached to NGS 126 and has established a Protocol Data Unit (PDU) session at operation 218. While attached to NGS 126, NG UE 136 may receive downlink (DL) data over NGS 126 at process 220 as controlled by a common PGW 114 and/or SMF/IP anchor 116. NG RAN 134 may send a handover (HO) required message 222 to NCG 120 which may include an NCG-CP 210 and an NGC-UP 212. NGC 120 may then send a relocation request message 224 to EPC 118 which in turn may include a Mobility Management Entity (MME) 214 and Serving Gateway (SGW) 216, and a message 228 to create a session may be sent between MME 214 and SGW 216. MME 214 may send and receive a handover request/acknowledgement (ACK) message 228 to/from Evolved UTRAN (E-UTRAN) 128. MME 214 may then send a relocation response message 230 to NGC-CP 210, which in turn sends a HO command message 232 to NG RAN 134, and which is sent as HO message 234 to NG UE 136 to execute the handover.

[00020] To complete the HO procedure, NG UE 136 sends a handover complete message 236 to E-UTRAN 128, which is forwarded to MME 214 as handover complete message 236. MME 214 then sends a modify bearer message 240 to SGW 216, which is forwarded to the common PGW 114 / SMF/IP anchor 116 as modify bearer message 242 to modify the bearer for NG UE 132 to EPS 14 for completion of the handover procedure 244. The common PGW 114 / SMF/IP anchor 116 now sends downlink data to NG UE 136 at procedure 246, and PGW 114 initiates activation of dedicated bearers for NG UE 136 at process 248.

[00021 ] Referring now to FIG. 3, a diagram of a tracking area update procedure in accordance with one or more embodiments will be discussed. The tracking area update (TAU) procedure 300 shown in FIG. 3 may be implemented in the where network 100 of FIG. 1 supports the NGx (N26) interface 122, and the NG UE 136 is in an idle mode when connected to NGS 126. In such a TAU procedure, NG UE 136 may trigger to start a TAU procedure at operation 322, and may send a TAU request message to eNodeB 310 of EPS 124, which may be forwarded to the new MME 314 of EPS 124 as message 326. The new MME 314 sends a context release message 328 to the old MME/old SGSN 316, which for NGS 126 may be the NG core 120, and may in return receive a context response message 330. Authentication messages 332 and 334 may then be transferred between NG UE 136 and HSS 110 via the new MME 314, and a context acknowledge message 336 may be sent to old MME 316 or NG Core 120. A create session request message 338 may then be sent to the new Serving Gateway (SGW) 318 of EPC 118 wherein bearer modification 340 may occur via the exchange of Modify Bearer Request message 342, PCEF initiated IP-CAN Session Modification message 344, and Modify Bearer Response message 346 among new Serving GW 318, old Serving GW 320, PDN GW 114, and PCRF 112. The new Serving GW 318 then sends a create session response message 348 to the new MME 314 which sends an update location message 350 to HSS 110 which in turn sends a cancel location message 352 to the old MME 316 or NG Core 120. The old MME 316 or NG Core 120 then sends a cancel location acknowledgement message 354 to HSS 110, and an Iu release command message 356 to Radio Network Controller (RNC) 312 of RAN 128, which responds with an Iu release complete message 358. HSS 110 sends an update location acknowledgement message 360 to new MME 314, and old MME 316 or NG Core 120 sends a delete session request message 362 to the old Serving GW 320 or NG Core 120. At this point 364, the old Serving Gateway 320 or NG Core 120 is able to release the NG UE 136, wherein the new MME 314 sends a TAU accept message 368 to NG UE 136, and the old Serving GW 320 or NG Core 120 sends a delete session response message 366 to the old MME 316 or equivalent device of NG Core 120. The NG UE 130 may then send a TAU complete message 370 to the new MME 314.

[00022] When NGx (N26) interface 122 is not supported, it still may be desirable to provide session continuity between NGS 126 and EPS 124, even if such a handover is not seamless. It should be noted that in one or more embodiments the term handover may be used herein in a broader sense as referring to any mobility procedure for NG UE 132 in connected mode that also accommodates session continuity. Examples of such procedures are Radio Resource Control (RRC) Connection Release with Redirection at access stratum, or a Handover Attach at a non- access stratum (NAS) level, although the scope of the claimed subject matter is not limited in these respects.

[00023] Upon mobility of NG UE 132 from NGS 126 to EPS 124, the NG UE 136 may perform the Handover Attach procedure on the target side at the EPS 124. The Handover Attach procedure is almost identical to the Attach procedure defined in 3 GPP Technical Standard (TS) 23.401, the only difference being that the NG UE 136 may set an indication in the PDN CONNECTIVITY session management message embedded within the ATTACH REQUEST mobility management message indicating to the network 100 that NG UE 136 is attaching as part of mobility from another system. Based on this handover indication, the target system EPS 124 is able to retrieve the PGW 114 that was used on the source side NGS 126 by making a query to the HSS 110 and thereby session continuity may be enabled.

[00024] In contrast, if NG UE 136 were to use a tracking area update (TAU) procedure 300 instead of a Handover Attach procedure when moving to the target side EPS 124, this almost certainly would result in a packet data network (PDN) connection release or Protocol Data Unit (PDU) Session release. The reason for this is that the TAU procedure was designed to retrieve UE context including Session Management (SM) context from the old system from the old MME. In the absence of NGx (N26) interface 122, the target MME is unable to retrieve the UE context and will force the UE into Attach procedure, with prior deletion of all UE context including SM context in the network 100.

[00025] In one or more embodiments, if NG UE 136 is in CN_Idle mode in NGS 126 and then reselects to EPS 124, it is proposed again to use the Handover Attach on the EPS 124 side since the use of a TAU procedure 300 may result in deletion of the SM context of NG UE 126. Thus, NG UE 136 should be aware of whether NGx (N26) interface 122 is supported in the network 100 or not. If NGx (N26) interface 122 is supported on the network 100, for an NG UE 136 that was in CN_Connected mode in NGS 126, upon mobility to EPS 124 the handover procedure 200 "Default bearer" handover and "dedicated bearer" reactivation may be performed. For a NG UE 136 that was in CN_Idle mode in NGS 126, upon mobility to EPS 125 the Tracking Area Update (TAU) procedure 300 may be performed.

[00026] In contrast, if NGx (N26) interface 122 is not supported on the network 100, the NG UE 136 always may perform a Handover Attach procedure 200, without performing a TAU procedure 300, upon mobility to EPS 124, regardless of the state, CN_Connected or CN_Idle, in which NG US 136 was connected on NGS 126. If NG UE 136 is in CN_Connected mode on NGS 126, the NG UE 136 is instructed by the network 100 about the procedure to follow on the target side at EPS 124 with an indication provided at access stratum. For example, if the handover procedure 200 "Default bearer" handover and "dedicated bearer" reactivation is used, the NG UE 136 receives a Handover Command message at access stratum if NGx (N26) interface 122 is supported. If NGx (N26) interface 122 is not supported, then NG UE 136 may receive an RRC Connection Release with Redirection message at access stratum. In either case, NG UE 136 may be tightly controlled by the network 100, and the NG UE 136 may be instructed about the procedure to use on the target side at EPS 124 either implicitly, for example via the type of access stratum message used to trigger the handover, or with an explicit indication contained inside the access stratum message.

[00027] If NG UE 136 is in CN_Idle mode on NGS 126, then NG UE 136 needs to be aware whether NGx (N26) interface 122 is supported on network 100 or not. Several ways are possible for indicating to the UE in this case whether NGx (N26) interface 122 is supported, which may influence NG UE 136 into deciding which procedure, Handover Attach procedure 200 or TAU procedure 300, to use when reselecting to EPS 124. For example, NG UE 136 may receive an indication upon an NGS Registration procedure, which may be equivalent to an EPS Attach procedure or an EPS TAU procedure, whether NGx (N26) interface is supported with the granularity of NGS Tracking Area. In such a procedure, it may be assumed that NGx (N26) interface 122 support in the network 100 is homogeneous within all cells belonging to the same Tracking Area. In another embodiment, NG UE 136 may receive an indication in the System Information Block (SIB) that is broadcasted on the target cell wherein the SIB may contain an indication whether NGx (N26) interface is supported. In this case, NGx (N26) interface 122 support in the network 100 may be on per-cell granularity which in some embodiments may involve modification on the eNodeB 310 of EPS 124 to include the additional information in the SIB.

[00028] In one or more embodiments, the same principles and procedures to accommodate a relocation of NG UE 136 from NGS 126 to EPS 124 also may be used to support mobility in the opposite direction from EPS 124 to NGS 126. In some embodiments, the EPS Attach procedure and EPS TAU procedure may be merged into a common NGS Registration procedure in the 5G system, in which case NG UE 136 may not need to select a specific NAS procedure when accessing the target system NGS 126 based on the presence or absence of NGS 126. In such embodiments, NG UE 136 may provide a specific indication such as Registration due to mobility from EPS 124 in order to trigger NGS 126 to fetch information from HSS 110 about the PGW 114 that was used on the source side, although the scope of the claimed subject matter is not limited in these respects.

[00029] In one or more embodiments, the internetworking between NG Core 120 and EPC 118 may be implemented in the 3GPP Technical Specification (TS) 23.501 as follows. 5.17.2 Interworking with EPC

5.17.2.1 General

In order to interwork with EPC, the UE that supports both 5GC and EPC NAS can operate in single-registration mode or dual-registration mode:

In single-registration mode, UE has only one active MM state (either RM state in 5GC or EMM state in EPC) and it is either in 5GC NAS mode or in EPC NAS mode (when connected to 5GC or EPC, respectively). UE maintains a single coordinated registration for 5GC and EPC.

In dual-registration mode, UE can handle independent registrations for 5GC and EPC. In this mode, the UE may be registered to 5GC only, EPC only, or to both 5GC and EPC.

The support of single registration mode is mandatory for UEs that support both 5GC and

EPC NAS.

During E-UTRAN Initial Attach, UE supporting both 5GC and EPC NAS shall indicate its support of 5G NAS in UE Network Capability described in clause 5.11.3 of TS 23.401 [26].

During registration to 5GC, UE supporting both 5GC and EPC NAS shall indicate its support of EPC NAS. NOTE: This indication may be used to give the priority towards selection of PGW-C + SMF for UEs that support both EPC and 5GC NAS.

Networks that support interworking with EPC, may support interworking procedures that use the N26 interface or interworking procedures that do not use the N26 interface. Interworking procedures with N26 support providing IP address continuity on inter-system mobility to UEs that support 5GC NAS and EPC NAS. Networks that support interworking procedures without N26 shall support procedures to provide IP address continuity on inter-system mobility to UEs operating in both single-registration mode and dual-registration mode.

In entire clause 5.17.2 the terms "initial attach", "handover attach" and "TAU" for the UE procedures in EPC can alternatively be combined EPS/IMSI Attach and combined TA/LA depending on the UE configuration definedin TS 23.221 [23].

5.17.2.2 Interworking Procedures with N26 interface

5.17.2.2.1 General

Interworking procedures using the N26 interface, enables the exchange of MM and SM states between the source and target network. Handover procedures are supported with the N26 interface. When interworking procedures with N26 is used, the UE operates in single-registration mode. The network keeps only one valid MM state for the UE, either in the AMF or MME. Either the AMF or the MME is registered in the HSS+UDM.

The support for N26 interface between AMF in 5GC and MME in EPC is required to enable seamless session continuity (e.g. for voice services) for inter-system change.

NOTE: When applying the AMF planned removal procedure or the procedure to handle AMF failures (see clause 5.21.2) implementations are expected to update the DNS configuration to enable MMEs to discover alternative AMFs if the MME tries to retrieve a UE context from an AMF that has been taken out of service or has failed. This addresses the scenario of UEs performing 5GC to EPC Idle mode mobility and presenting a mapped GUTI pointing to an AMF that has been taken out of service or has failed.

5.17.2.2.2 Mobility for UEs in single-registration mode

When the UE supports single-registration mode and network supports interworking procedure with the N26 interface:

- For idle-mode mobility from 5GC to EPC, the UE performs TAU procedure with

EPS GUTI mapped from 5 G- GUTI sent as old Native GUTI. The MME retrieves the UE's MM and SM context from 5GC if the UE has a PDU session established or if the UE or the EPC support "attach without PDN connectivity". The UE performs an attach procedure if the UE is registered without PDU session in 5GC and the UE or the EPC does not support attach without PDN connectivity. For connected-mode mobility from 5GC to EPC, inter-system handover is performed. During the TAU or Attach procedure the HSS+UDM cancels any AMF registration.

For idle-mode mobility from EPC to 5GC, the UE performs registration procedure with the EPS GUTI sent as the old GUTI. The AMF and SMF retrieve the UE's MM and SM context from EPC. For connected-mode mobility from EPC to 5GC, inter-system handover is performed. During the Registration procedure, the HSS+UDM cancels any MME registration. 5.17.2.3 Interworking Procedures without N26 interface

5.17.2.3.1 General

For interworking without the N26 interface, IP address continuity is provided to the UEs on inter-system mobility by storing and fetching PGW-C+SMF and corresponding APN/DDN information via the HSS+UDM. Such networks also provide an indication that dual registration mode is supported to UEs during initial Registration in 5GC. This indication is valid for the entire PLMN. UEs that operate in dual-registration mode may use this indication to decide whether to register early in the target system. UEs that operate in single-registration mode may use this indication as described in clause 5.17.2.3.2.

NOTE: If the network needs to remove the indication (e.g. due to UE entering an area where procedures for interworking with the N26 interface are supported) the network can deregister the UE with an indication to re-register, and upon re-registration the network does not provide the indication that dual registration mode is supported.

Interworking procedures without N26 interface use the following two features:

1. When PDU session are created in 5GC, the PGW-C+SMF updates its information along with DNN in the HSS+UDM.

2. The HSS+UDM provides the information about dynamically allocated PGW- C+SMF and APN/DNN information to the target CN network.

To support mobility for dual-registration mode UEs, the following also are supported by the network:

3. When UE performs Initial Attach in EPC and provides an indication that the old node was an AMF, the MME does not include "initial attach" indicator to the HSS+UDM. This results in HSS+UDM not cancelling the registration of AMF, if any.

4. When UE performs Initial Registration in 5GC and provides the EPS GUTI, the

AMF does not include "initial attach" indicator to the HSS+UDM. This results in HSS+UDM not cancelling the registration of MME, if any.

5. When PDN connections are created in EPC, the MME stores the PGW-C+SMF and APN information in the HSS+UDM. To provide IP address preservation to UEs operating in single-registration mode when the UE moves from 5GC to EPC, the network supports item 3.

NOTE 1 : Items 4 and 5 are also supported in networks that support interworking with N26 procedures. This enables a VPLMN that does not deploy N26 interface to provide IP address continuity to roamed-in single-registration mode UEs from a HPLMN that only supports interworking with N26 procedures.

To provide IP address preservation to UEs operating in single-registration mode when the UE moves from EPC to 5GC, the network supports item 4 and 5 and the following below:

7. When UE performs mobility Registration in 5GC and provides an EPS GUTI, the AMF determines that the old node is MME and proceeds with the procedure and provides a "Handover PDU Session Setup with EPC Supported" indication to the UE in the Registration Accept message.

Networks that support 5GS-EPS interworking procedures without N26 interface do not need to provide the UEs with mapped target system parameters (e.g. QoS parameters, bearer IDs/QFI, PDU session ID, etc.) of the target system when UE is in the source network.

When an AMF in such a network receives a request to allocate an EBI(s) for a QoS flow(s) from a PGW-C+SMF, it may not provide the EBI(s).

NOTE 2: A UE in a VPLMN that supports interworking without N26 may be provided with mapped QoS parameters from PGW-C+SMF in HPLMN for home-routed PDN connection, if the HPLMN supports interworking procedures with N26 interface.

NOTE 3: MMEs not supporting interworking without N26 interface are not required to process an indication from the UE that the old node was an AMF.

A UE that operates in dual registration mode ignores any received mapped target system parameters (e.g. QoS parameters, bearer IDs/QFI, PDU session ID, etc.).

5.17.2.3.2 Mobility for UEs in single-registration mode

When the UE supports single-registration mode and network supports interworking procedure without N26 interface:

For mobility from 5GC to EPC, the UE that has received the network indication that dual registration mode is supported may either:

- perform Attach in EPC with Request type "Handover" in PDN CONNECTIVITY

Request message (TS 23.401 [26], clause 5.3.2.1) and subsequently moves all its other PDU session using the UE requested PDN connectivity establishment procedure with Request Type "handover" flag (TS 23.401 [26] clause 5.10.2), or. perform TAU with 4G-GUTI mapped from 5 G- GUTI (TS 23.401 [26], clause 5.3.3), in which case the MME instructs the UE to re-attach. IP address preservation is not provided in this case.

NOTE 1 : The first PDN connection may be established during the E-UTRAN Initial Attach procedure (see TS 23.401 [26]).

NOTE 2: At inter-PLMN mobility the UE always uses the TAU procedure.

For mobility from EPC to 5GC, the UE performs Registration of type "mobility registration update" in 5GC with 5G-GUTI mapped from EPS GUTI. The AMF determines that old node is an MME, but proceeds as if the Registration is of type "initial registration". The Registration Accept includes "Handover PDU Session Setup Support" indication to the UE. Based on this indication, the UE may subsequently either:

move all its PDN connections from EPC using the UE initiated PDU session establishment procedure with "Existing PDU Sessions" flag (TS 23.502 [3], clause 4.3.2.2.1), or re-establish PDU sessions corresponding to the PDN connections that it had in EPS. IP address preservation is not provided in this case.

5.17.2.3.3 Mobility for UEs in dual-registration mode

To support mobility in dual-registration mode, the support of N26 interface between AMF in 5GC and MME in EPC is not required.

Editor's note: It is FFS if dual-registration mode can be used for IMS voice.

For UE operating in dual-registration mode the following principles apply for PDU session transfer from 5GC to EPC:

UE operating in Dual Registration mode may register in EPC ahead of any PDU session transfer using the Attach procedure without establishing a PDN Connection in EPC if the EPC supports EPS Attach without PDN Connectivity as defined in TS 23.401 [26]. Support for EPS Attach without PDN Connectivity is mandatory for UE supporting dual-registration procedures.

NOTE 1 : Before attempting early registration in EPC the UE needs to check whether EPC supports EPS Attach without PDN Connectivity by reading the related SIB in the target cell.

UE performs PDU session transfer from 5GC to EPC using the UE initiated PDN connection establishment procedure with "handover" indication in the PDN Connection Request message (TS 23.401 [26], clause 5.10.2).

If the UE has not registered with EPC ahead of the PDU session transfer, the UE can perform Attach in EPC with "handover" indication in the PDN Connection Request message (TS 23.401 [26], clause 5.3.2.1). UE may selectively transfer certain PDU sessions to EPC, while keeping other PDU Sessions in 5GC.

UE may maintain the registration up to date in both 5GC and EPC by re-registering periodically in both systems. If the registration in either 5GC or EPC times out (e.g. upon mobile reachable timer expiry), the corresponding network starts an implicit detach timer.

NOTE 2: Whether UE transfers some or all PDU sessions on the EPC side and whether it maintains the registration up to date in both EPC and 5GC can depend on UE capabilities that are implementation dependent. The information for determining which PDU sessions are transferred on EPC side and the triggers can be pre-configured in the UE and are not specified in this release of the specification.

For UE operating in dual-registration mode the following principles apply for PDN connection transfer from EPC to 5GC:

UE operating in Dual Registration mode may register in 5GC ahead of any PDN connection transfer using the Registration procedure without establishing a PDU session in 5GC (TS 23.502 [3], clause 4.2.2.2.2).

UE performs PDN connection transfer from EPC to 5GC using the UE initiated PDU session establishment procedure with "Existing PDU Session" indication (TS 23.502 [3], clause 4.3.2.2.1).

If the UE has not registered with 5GC ahead of the PDN connection transfer, the UE can perform Registration in 5GC with "Existing PDU Session" indication in the PDU Session Request message.

Editor's note: Support of Registration combined with PDU Session Request in TS 23.502 [3] is not yet defined.

UE may selectively transfer certain PDN connections to 5GC, while keeping other PDN Connections in EPC.

UE may maintain the registration up to date in both EPC and 5GC by re-registering periodically in both systems. If the registration in either EPC or 5GC times out (e.g. upon mobile reachable timer expiry), the corresponding network starts an implicit detach timer.

NOTE 3: Whether UE transfers some or all PDN connections on the 5GC side and whether it maintains the registration up to date in both 5GC and EPC can depend on UE capabilities that are implementation dependent. The information for determining which PDN connections are transferred on 5GC side and the triggers can be pre-configured in the UE and are not specified in this release of the specification. NOTE 4: If EPC does not support EPS Attach without PDN Connectivity the MME detaches the UE when the last PDN connection is released by the PGW as described in TS 23.401 [26] clause 5.4.4.1 (in relation to transfer of the last PDN connection to non-3GPP access).

When sending a control plane request for MT services (e.g. MT SMS) the network routes it via either the EPC or the 5GC. In absence of UE response, the network should attempt routing the control plane request via the other system.

NOTE 5: The choice of the system through which the network attempts to deliver the control plane request first is left to network configuration.

[00030] FIG. 4 illustrates an architecture of a system of a network in accordance with some embodiments. System 400 may illustrate any one or more of the nodes or devices of network 100. The system 400 is shown to include a user equipment (UE) 401 and a UE 402. The UEs 401 and 402 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, or any computing device including a wireless communications interface.

[00031 ] In some embodiments, any of the UEs 401 and 402 can comprise an Internet of Things (IoT) UE, which can comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. An IoT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network describes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network.

[00032] The UEs 401 and 402 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 410— the RAN 410 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E- UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs 401 and 402 utilize connections 403 and 404, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 403 and 404 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3 GPP Long Term Evolution (LTE) protocol, a fifth generation (5G) protocol, a New Radio (NR) protocol, and the like.

[00033] In this embodiment, the UEs 401 and 402 may further directly exchange communication data via a ProSe interface 405. The ProSe interface 405 may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH).

[00034] In some embodiments, the UE 402 is shown to be configured to access an access point (AP) 406 via connection 407, although the scope of the claimed subject matter is not limited in this respect. The connection 407 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.11 protocol, wherein the AP 406 would comprise a wireless fidelity (WiFi®) router. In this example, the AP 406 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

[00035] The RAN 410 can include one or more access nodes that enable the connections 403 and 404. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), next Generation NodeBs (gNB), RAN nodes, and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). The RAN 410 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 411, and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 412.

[00036] Any of the RAN nodes 411 and 412 can terminate the air interface protocol and can be the first point of contact for the UEs 401 and 402. In some embodiments, any of the RAN nodes 411 and 412 can fulfill various logical functions for the RAN 410 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

[00037] In accordance with some embodiments, the UEs 401 and 402 can be configured to communicate using Orthogonal Frequency-Division Multiplexing (OFDM) communication signals with each other or with any of the RAN nodes 411 and 412 over a multicarrier communication channel in accordance various communication techniques, such as, but not limited to, an Orthogonal Frequency-Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC- FDMA) communication technique (e.g., for uplink and ProSe or sidelink communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

[00038] In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 411 and 412 to the UEs 401 and 402, while uplink transmissions can utilize similar techniques. The grid can be a time-frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time- frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

[00039] The physical downlink shared channel (PDSCH) may carry user data and higher- layer signaling to the UEs 401 and 402. The physical downlink control channel (PDCCH) may carry information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 401 and 402 about the transport format, resource allocation, and H-ARQ (Hybrid Automatic Repeat Request) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 102 within a cell) may be performed at any of the RAN nodes 411 and 412 based on channel quality information fed back from any of the UEs 401 and 402. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 401 and 402.

[00040] The PDCCH may use control channel elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex-valued symbols may first be organized into quadruplets, which may then be permuted using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as resource element groups (REGs). Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=l, 2, 4, or 8).

[00041 ] Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced physical downlink control channel (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced the control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as an enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

[00042] The RAN 410 is shown to be communicatively coupled to a core network (CN) 420 — via an SI interface 413. In embodiments, the CN 420 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN. In this embodiment the SI interface 413 is split into two parts: the Sl-U interface 414, which carries traffic data between the RAN nodes 411 and 412 and the serving gateway (S-GW) 422, and the Sl-mobility management entity (MME) interface 415, which is a signaling interface between the RAN nodes 411 and 412 and MMEs 421.

[00043] In this embodiment, the CN 420 comprises the MMEs 421, the S-GW 422, the Packet Data Network (PDN) Gateway (P-GW) 423, and a home subscriber server (HSS) 424. The MMEs 421 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 421 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 424 may comprise a database for network users, including subscription-related information to support the network entities' handling of communication sessions. The CN 420 may comprise one or several HSSs 424, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 424 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc.

[00044] The S-GW 422 may terminate the SI interface 413 towards the RAN 410, and routes data packets between the RAN 410 and the CN 420. In addition, the S-GW 422 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement.

[00045] The P-GW 423 may terminate an SGi interface toward a PDN. The P-GW 423 may route data packets between the EPC network 423 and external networks such as a network including the application server 430 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 425. Generally, the application server 430 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this embodiment, the P-GW 423 is shown to be communicatively coupled to an application server 430 via an IP communications interface 425. The application server 430 can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 401 and 402 via the CN 420.

[00046] The P-GW 423 may further be a node for policy enforcement and charging data collection. Policy and Charging Enforcement Function (PCRF) 426 is the policy and charging control element of the CN 420. In a non-roaming scenario, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with local breakout of traffic, there may be two PCRFs associated with a UE's IP-CAN session: a Home PCRF (H-PCRF) within a HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 426 may be communicatively coupled to the application server 430 via the P-GW 423. The application server 430 may signal the PCRF 426 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 426 may provision this rule into a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate traffic flow template (TFT) and QoS class of identifier (QCI), which commences the QoS and charging as specified by the application server 430.

[00047] FIG. 5 illustrates example components of a device 500 in accordance with some embodiments. Device 500 may realize any of the network nodes or devices shown in FIG. 1, with greater of fewer components depending on the particular node or device. In some embodiments, the device 500 may include application circuitry 502, baseband circuitry 504, Radio Frequency (RF) circuitry 506, front-end module (FEM) circuitry 508, one or more antennas 510, and power management circuitry (PMC) 512 coupled together at least as shown. The components of the illustrated device 500 may be included in a UE or a RAN node. In some embodiments, the device 500 may include less elements (e.g., a RAN node may not utilize application circuitry 502, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 500 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud- RAN (C-RAN) implementations).

[00048] The application circuitry 502 may include one or more application processors. For example, the application circuitry 502 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the device 500. In some embodiments, processors of application circuitry 502 may process IP data packets received from an EPC.

[00049] The baseband circuitry 504 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 504 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 506 and to generate baseband signals for a transmit signal path of the RF circuitry 506. Baseband processing circuity 504 may interface with the application circuitry 502 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 506. For example, in some embodiments, the baseband circuitry 504 may include a third generation (3G) baseband processor 504A, a fourth generation (4G) baseband processor 504B, a fifth generation (5G) baseband processor 504C, or other baseband processor(s) 504D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuitry 504 (e.g., one or more of baseband processors 504A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 506. In other embodiments, some or all of the functionality of baseband processors 504A-D may be included in modules stored in the memory 504G and executed via a Central Processing Unit (CPU) 504E. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 504 may include Fast-Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 504 may include convolution, tail-biting convolution, turbo, Viterbi, or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[00050] In some embodiments, the baseband circuitry 504 may include one or more audio digital signal processor(s) (DSP) 504F. The audio DSP(s) 504F may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 504 and the application circuitry 502 may be implemented together such as, for example, on a system on a chip (SOC).

[00051 ] In some embodiments, the baseband circuitry 504 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 504 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 504 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[00052] RF circuitry 506 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 506 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 506 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 508 and provide baseband signals to the baseband circuitry 504. RF circuitry 506 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 504 and provide RF output signals to the FEM circuitry 508 for transmission.

[00053] In some embodiments, the receive signal path of the RF circuitry 506 may include mixer circuitry 506a, amplifier circuitry 506b and filter circuitry 506c. In some embodiments, the transmit signal path of the RF circuitry 506 may include filter circuitry 506c and mixer circuitry 506a. RF circuitry 506 may also include synthesizer circuitry 506d for synthesizing a frequency for use by the mixer circuitry 506a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 506a of the receive signal path may be configured to down- convert RF signals received from the FEM circuitry 508 based on the synthesized frequency provided by synthesizer circuitry 506d. The amplifier circuitry 506b may be configured to amplify the down-converted signals and the filter circuitry 506c may be a low-pass filter (LPF) or bandpass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 504 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 506a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[00054] In some embodiments, the mixer circuitry 506a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 506d to generate RF output signals for the FEM circuitry 508. The baseband signals may be provided by the baseband circuitry 504 and may be filtered by filter circuitry 506c.

[00055] In some embodiments, the mixer circuitry 506a of the receive signal path and the mixer circuitry 506a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 506a of the receive signal path and the mixer circuitry 506a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 506a of the receive signal path and the mixer circuitry 506a may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 506a of the receive signal path and the mixer circuitry 506a of the transmit signal path may be configured for super-heterodyne operation.

[00056] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 506 may include analog-to-digital converter (ADC) and digital-to- analog converter (DAC) circuitry and the baseband circuitry 504 may include a digital baseband interface to communicate with the RF circuitry 506.

[00057] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect. In some embodiments, the synthesizer circuitry 506d may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 506d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[00058] The synthesizer circuitry 506d may be configured to synthesize an output frequency for use by the mixer circuitry 506a of the RF circuitry 506 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 506d may be a fractional N/N+l synthesizer.

[00059] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 504 or the applications processor 502 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a lookup table based on a channel indicated by the applications processor 502. [00060] Synthesizer circuitry 506d of the RF circuitry 506 may include a divider, a delay- locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+l (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[00061 ] In some embodiments, synthesizer circuitry 506d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry 506 may include an IQ/polar converter.

[00062] FEM circuitry 508 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 510, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 506 for further processing. FEM circuitry 508 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 506 for transmission by one or more of the one or more antennas 510. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 506, solely in the FEM 508, or in both the RF circuitry 506 and the FEM 508.

[00063] In some embodiments, the FEM circuitry 508 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 506). The transmit signal path of the FEM circuitry 508 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 506), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 510).

[00064] In some embodiments, the PMC 512 may manage power provided to the baseband circuitry 504. In particular, the PMC 512 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 512 may often be included when the device 500 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 512 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

[00065] While FIG. 5 shows the PMC 512 coupled only with the baseband circuitry 504. However, in other embodiments, the PMC 5 12 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 502, RF circuitry 506, or FEM 508.

[00066] In some embodiments, the PMC 512 may control, or otherwise be part of, various power saving mechanisms of the device 500. For example, if the device 500 is in an RRC_Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 500 may power down for brief intervals of time and thus save power.

[00067] If there is no data traffic activity for an extended period of time, then the device 500 may transition off to an RRC_Idle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 500 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 500 may not receive data in this state, in order to receive data, it must transition back to RRC_Connected state.

[00068] An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours). During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

[00069] Processors of the application circuitry 502 and processors of the baseband circuitry 504 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 504, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 504 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may comprise a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below. [00070] FIG. 6 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 504 of FIG. 5 may comprise processors 504A-504E and a memory 504G utilized by said processors. Each of the processors 504A-504E may include a memory interface, 604A-604E, respectively, to send/receive data to/from the memory 504G.

[00071 ] The baseband circuitry 504 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 612 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 504), an application circuitry interface 614 (e.g., an interface to send/receive data to/from the application circuitry 502 of FIG. 5), an RF circuitry interface 616 (e.g., an interface to send/receive data to/from RF circuitry 506 of FIG. 5), a wireless hardware connectivity interface 618 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components), and a power management interface 620 (e.g., an interface to send/receive power or control signals to/from the PMC 512.

[00072] The following are example implementations of the subject matter described herein. It should be noted that any of the examples and the variations thereof described herein may be used in any permutation or combination of any other one or more examples or variations, although the scope of the claimed subject matter is not limited in these respects.

[00073] In example one, an apparatus of a NextGen user equipment (NG UE) comprises one or more baseband processors to decode a message indicating whether an N26 interface exists between a NextGen Core (NGC) and an Evolved Packet Core (EPC), and to initiate a mobility procedure with session continuity if the NG UE is to relocate from the NGC to the EPC, the mobility procedure being dependent on whether the N26 interface exists or not, and a memory to store the message. Example two may include the subject matter of example one or any of the examples described herein, wherein the NGC and the EPC share a common Home Subscriber Server and User Data Management (HSS + UDM) database and a common Internet Protocol (IP) anchor. Example three may include the subject matter of example one or any of the examples described herein, wherein the one or more baseband processors are to initiate a tracking area update (TAU) procedure if the NG UE is in CN_Idle mode and if the message indicates that an N26 control plane interface exists between the NGC and the EPC. Example four may include the subject matter of example one or any of the examples described herein, wherein the one or more baseband processors are to determine if the NG UE in CN_Connected mode is to use a conventional handover procedure or a handover attach procedure based on the message being a Handover Command message or a Radio Resource Control (RRC) Connection Release with Redirection message, respectively. Example five may include the subject matter of example one or any of the examples described herein, wherein the one or more band processors determine to use the handover attach procedure if the RRC Connection Release with Redirection message indicates that no N26 control plane interface exists between the NGC and the EPC. Example six may include the subject matter of example one or any of the examples described herein, wherein the one or more band processors determine to use a handover attach procedure if the NG UE is in CN_Idle mode and if the message indicates that no N26 control plane interface exists between the NGC and the EPC. Example seven may include the subject matter of example one or any of the examples described herein, wherein the message is a non-access stratum message and wherein the message comprises a NextGen System (NGS) Registration Accept message received upon registration or re-registration with the NGC. Example eight may include the subject matter of example one or any of the examples described herein, wherein the message is a broadcast access stratum message and wherein the message comprises an explicit indication broadcast in a target cell of the EPC. Example nine may include the subject matter of example one or any of the examples described herein, wherein the EPC includes a radio network comprising a General Packet Radio System (GPRS), a Universal Mobile Telecommunications System (UMTS), a Long-Term Evolution (LTE) system, or an LTE-anchored New Radio (NR) system, or a combination thereof. Example ten may include the subject matter of example one or any of the examples described herein, wherein the N26 interface comprises a control plane internetworking interface.

[00074] In example eleven, one or more machine-readable media may have instructions stored thereon that, if executed by an apparatus of a NextGen user equipment (NG UE), result in decoding a message indicating whether an N26 interface exists between a NextGen Core (NGC) and an Evolved Packet Core (EPC), and to initiate a mobility procedure with session continuity if the NG UE is to relocate from the NGC to the EPC, the mobility procedure being dependent on whether the N26 interface exists or not, and storing the message in a memory. Example twelve may include the subject matter of example eleven or any of the examples described herein, wherein the NGC and the EPC share a common Home Subscriber Server and User Data Management (HSS + UDM) database and a common Internet Protocol (IP) anchor. Example thirteen may include the subject matter of example eleven or any of the examples described herein, wherein the instructions, if executed, further result in initiating a tracking area update (TAU) procedure if the NG UE is in CN_Idle mode and if the message indicates that an N26 control plane interface exists between the NGC and the EPC. Example fourteen may include the subject matter of example eleven or any of the examples described herein, wherein the instructions, if executed, further result in determining if the NG UE in CN_Connected mode is to use a conventional handover procedure or a handover attach procedure based on the message being a Handover Command message or a Radio Resource Control (RRC) Connection Release with Redirection message, respectively. Example fifteen may include the subject matter of example eleven or any of the examples described herein, wherein the instructions, if executed, further result in determining to use the handover attach procedure if the RRC Connection Release with Redirection message indicates that no N26 control plane interface exists between the NGC and the EPC. Example sixteen may include the subject matter of example eleven or any of the examples described herein, wherein the instructions, if executed, further result in determining to use a handover attach procedure if the NG UE is in CN_Idle mode and if the message indicates that no N26 control plane interface exists between the NGC and the EPC. Example seventeen may include the subject matter of example eleven or any of the examples described herein, wherein the message is a non-access stratum message and wherein the message comprises a NextGen System (NGS) Registration Accept message received upon registration or re-registration with the NGC. Example eighteen may include the subject matter of example eleven or any of the examples described herein, wherein the message is a broadcast access stratum message and wherein the message comprises an explicit indication broadcast in a target cell of the EPC. Example nineteen may include the subject matter of example eleven or any of the examples described herein, wherein the EPC include radio network comprising a General Packet Radio System (GPRS), a Universal Mobile Telecommunications System (UMTS), a Long-Term Evolution (LTE) system, or an LTE-anchored New Radio (NR) system, or a combination thereof. Example twenty may include the subject matter of example eleven or any of the examples described herein, wherein the N26 interface comprises a control plane internetworking interface.

[00075] In example twenty-one, an apparatus of a NextGen user equipment (NG UE) comprises means for decoding a message indicating whether an N26 interface exists between a NextGen Core (NGC) and an Evolved Packet Core (EPC), and to initiate a mobility procedure with session continuity if the NG UE is to relocate from the NGC to the EPC, the mobility procedure being dependent on whether the N26 interface exists or not, and means for storing the message in a memory. Example twenty-two may include the subject matter of example twenty- one or any of the examples described herein, wherein the NGC and the EPC share a common Home Subscriber Server and User Data Management (HSS + UDM) database and a common Internet Protocol (IP) anchor. Example twenty-three two may include the subject matter of example twenty-one or any of the examples described herein, further comprising means for initiating a tracking area update (TAU) procedure if the NG UE is in CN_Idle mode and if the message indicates that an N26 control plane interface exists between the NGC and the EPC. Example twenty-four two may include the subject matter of example twenty-one or any of the examples described herein, further comprising means for determining if the NG UE in CN_Connected mode is to use a conventional handover procedure or a handover attach procedure based on the message being a Handover Command message or a Radio Resource Control (RRC) Connection Release with Redirection message, respectively. Example twenty-five two may include the subject matter of example twenty-one or any of the examples described herein, further comprising means for determining to use the handover attach procedure if the RRC Connection Release with Redirection message indicates that no N26 control plane interface exists between the NGC and the EPC. Example twenty-six two may include the subject matter of example twenty- one or any of the examples described herein, further comprising means for determining to use a handover attach procedure if the NG UE is in CN_Idle mode and if the message indicates that no N26 control plane interface exists between the NGC and the EPC. Example twenty-seven two may include the subject matter of example twenty-one or any of the examples described herein, wherein the message is a non-access stratum message and wherein the message comprises a NextGen System (NGS) Registration Accept message received upon registration or re-registration with the NGC. Example twenty-eight two may include the subject matter of example twenty-one or any of the examples described herein, wherein the message is a broadcast access stratum message and wherein the message comprises an explicit indication broadcast in a target cell of the EPC. Example twenty-nine two may include the subject matter of example twenty-one or any of the examples described herein, wherein the EPC include radio network comprising a General Packet Radio System (GPRS), a Universal Mobile Telecommunications System (UMTS), a Long- Term Evolution (LTE) system, or an LTE-anchored New Radio (NR) system, or a combination thereof. Example thirty-two may include the subject matter of example twenty-one or any of the examples described herein, wherein the N26 interface comprises a control plane internetworking interface. In example thirty-one, machine-readable storage may include machine-readable instructions, when executed, to realize an apparatus as claimed in any preceding claim.

[00076] In the description herein and/or claims, the terms coupled and/or connected, along with their derivatives, may be used. In particular embodiments, connected may be used to indicate that two or more elements are in direct physical and/or electrical contact with each other. Coupled may mean that two or more elements are in direct physical and/or electrical contact. Coupled, however, may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate and/or interact with each other. For example, "coupled" may mean that two or more elements do not contact each other but are indirectly joined together via another element or intermediate elements. Finally, the terms "on," "overlying," and "over" may be used in the following description and claims. "On," "overlying," and "over" may be used to indicate that two or more elements are in direct physical contact with each other. It should be noted, however, that "over" may also mean that two or more elements are not in direct contact with each other. For example, "over" may mean that one element is above another element but not contact each other and may have another element or elements in between the two elements. Furthermore, the term "and/or" may mean "and", it may mean "or", it may mean "exclusive-or", it may mean "one", it may mean "some, but not all", it may mean "neither", and/or it may mean "both", although the scope of claimed subject matter is not limited in this respect. In the description herein and/or claims, the terms "comprise" and "include," along with their derivatives, may be used and are intended as synonyms for each other.

[00077] Although the claimed subject matter has been described with a certain degree of particularity, it should be recognized that elements thereof may be altered by persons skilled in the art without departing from the spirit and/or scope of claimed subject matter. It is believed that the subject matter pertaining to internetworking between next generation core and evolved packet core and many of its attendant utilities will be understood by the forgoing description, and it will be apparent that various changes may be made in the form, construction and/or arrangement of the components thereof without departing from the scope and/or spirit of the claimed subject matter or without sacrificing all of its material advantages, the form herein before described being merely an explanatory embodiment thereof, and/or further without providing substantial change thereto. It is the intention of the claims to encompass and/or include such changes.

Claims

What is claimed is: 1. An apparatus of a NextGen user equipment (NG UE), comprising:

one or more baseband processors to decode a message indicating whether an N26 interface exists between a NextGen Core (NGC) and an Evolved Packet Core (EPC), and to initiate a mobility procedure with session continuity if the NG UE is to relocate from the NGC to the EPC, the mobility procedure being dependent on whether the N26 interface exists or not; and

a memory to store the message.

2. The apparatus of claim 1, wherein the NGC and the EPC share a common Home Subscriber Server and User Data Management (HSS + UDM) database and a common Internet Protocol (IP) anchor.

3. The apparatus of any one of claims 1-2, wherein the one or more baseband processors are to initiate a tracking area update (TAU) procedure if the NG UE is in CN_Idle mode and if the message indicates that an N26 control plane interface exists between the NGC and the EPC.

4. The apparatus of any one of claims 1-3, wherein the one or more baseband processors are to determine if the NG UE in CN_Connected mode is to use a conventional handover procedure or a handover attach procedure based on the message being a Handover Command message or a Radio Resource Control (RRC) Connection Release with Redirection message, respectively.

5. The apparatus of claim 4, wherein the one or more band processors determine to use the handover attach procedure if the RRC Connection Release with Redirection message indicates that no N26 control plane interface exists between the NGC and the EPC.

6. The apparatus of any one of claims 1-5, wherein the one or more band processors determine to use a handover attach procedure if the NG UE is in CN_Idle mode and if the message indicates that no N26 control plane interface exists between the NGC and the EPC.

7. The apparatus of claim 3 or claim 6, wherein the message is a non-access stratum message and wherein the message comprises a NextGen System (NGS) Registration Accept message received upon registration or re-registration with the NGC.

8. The apparatus of claim 3 or claim 6, wherein the message is a broadcast access stratum message and wherein the message comprises an explicit indication broadcast in a target cell of the EPC.

9. The apparatus of any one of claims 1-8, wherein the EPC includes a radio network comprising a General Packet Radio System (GPRS), a Universal Mobile Telecommunications System (UMTS), a Long-Term Evolution (LTE) system, or an LTE-anchored New Radio (NR) system, or a combination thereof.

10. The apparatus of any one of claims 1-9, wherein the N26 interface comprises a control plane internetworking interface.

11. One or more machine-readable media having instructions stored thereon that, if executed by an apparatus of a NextGen user equipment (NG UE), result in:

decoding a message indicating whether an N26 interface exists between a NextGen Core (NGC) and an Evolved Packet Core (EPC), and to initiate a mobility procedure with session continuity if the NG UE is to relocate from the NGC to the EPC, the mobility procedure being dependent on whether the N26 interface exists or not; and

storing the message in a memory.

12. The one or more machine-readable media of claim 11, wherein the NGC and the EPC share a common Home Subscriber Server and User Data Management (HSS + UDM) database and a common Internet Protocol (IP) anchor.

13. The one or more machine-readable media of any one of claims 11-12, wherein the instructions, if executed, further result in initiating a tracking area update (TAU) procedure if the NG UE is in CN_Idle mode and if the message indicates that an N26 control plane interface exists between the NGC and the EPC.

14. The one or more machine-readable media of any one of claims 11-13, wherein the instructions, if executed, further result in determining if the NG UE in CN_Connected mode is to use a conventional handover procedure or a handover attach procedure based on the message being a Handover Command message or a Radio Resource Control (RRC) Connection Release with Redirection message, respectively.

15. The one or more machine-readable media of claim 14, wherein the instructions, if executed, further result in determining to use the handover attach procedure if the RRC Connection Release with Redirection message indicates that no N26 control plane interface exists between the NGC and the EPC.

16. The one or more machine-readable media of any one of claims 11-15 wherein the instructions, if executed, further result in determining to use a handover attach procedure if the NG UE is in CN_Idle mode and if the message indicates that no N26 control plane interface exists between the NGC and the EPC.

17. The one or more machine-readable media of claim 13 or claim 16, wherein the message is a non-access stratum message and wherein the message comprises a NextGen System (NGS) Registration Accept message received upon registration or re-registration with the NGC.

18. The one or more machine-readable media of claim 13 or claim 16, wherein the message is a broadcast access stratum message and wherein the message comprises an explicit indication broadcast in a target cell of the EPC.

19. The one or more machine-readable media of any one of claims 11-18, wherein the

EPC include radio network comprising a General Packet Radio System (GPRS), a Universal Mobile Telecommunications System (UMTS), a Long-Term Evolution (LTE) system, or an LTE- anchored New Radio (NR) system, or a combination thereof.

20. The one or more machine-readable media of any one of claims 11-19, wherein the N26 interface comprises a control plane internetworking interface.