1、 ETSI TS 138 420 V15.0.0 (2018-07) 5G; NG-RAN; Xn general aspects and principles (3GPP TS 38.420 version 15.0.0 Release 15) TECHNICAL SPECIFICATION ETSI ETSI TS 138 420 V15.0.0 (2018-07)13GPP TS 38.420 version 15.0.0 Release 15Reference RTS/TSGR-0338420vf00 Keywords 5G ETSI 650 Route des Lucioles F-
2、06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org/standards-sea
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8、he 3GPP Organizational Partners. oneM2M logo is protected for the benefit of its Members. GSMand the GSM logo are trademarks registered and owned by the GSM Association. ETSI ETSI TS 138 420 V15.0.0 (2018-07)23GPP TS 38.420 version 15.0.0 Release 15Intellectual Property Rights Essential patents IPRs
9、 essential or potentially essential to normative deliverables may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or p
10、otentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (https:/ipr.etsi.org/). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI
11、. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Trademarks The present document may include trademarks and/or tradenames which are asserted
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13、SI of products, services or organizations associated with those trademarks. Foreword This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identiti
14、es or GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables. The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall“, “shall no
15、t“, “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct cit
16、ation. ETSI ETSI TS 138 420 V15.0.0 (2018-07)33GPP TS 38.420 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 5g31 Scope 6g32 References 6g33 Definitions and abbreviations . 6g33.1 Definitions 6g33.2 Abbreviations . 6g34 General as
17、pects . 7g34.1 Introduction 7g34.2 Xn interface general principles . 7g34.3 Xn interface specification objectives 7g34.4 Xn interface capabilities . 7g35 Functions of the Xn interface . 7g35.1 General . 7g35.2 Functions of Xn-C 7g35.2.1 Xn-C interface management and error handling functions . 7g35.2
18、.1.1 General 7g35.2.1.2 Xn Setup function . 7g35.2.1.3 Error Indication function . 8g35.2.1.4 Xn reset function . 8g35.2.1.5 Xn configuration data update function 8g35.2.1.6 Xn removal function . 8g35.2.2 UE mobility management functions . 8g35.2.2.1 Handover preparation function 8g35.2.2.2 Handover
19、 cancellation function 8g35.2.2.3 Retrieve UE Context function . 8g35.2.2.4 RAN Paging function 8g35.2.2.5 Data Forwarding control function . 8g35.2.3 Dual connectivity function 8g35.2.4 Energy saving function . 8g35.3 Functions of Xn-U 8g35.3.1 Data transfer function . 8g35.3.2 Flow control functio
20、n 8g36 Xn interface procedures 9g36.1 General . 9g36.2 Control plane protocol procedures . 9g36.2.1 Mobility management procedures. 9g36.2.2 Dual Connectivity procedures. 9g36.2.3 Global procedures . 9g36.2.4 Interface Management procedures 9g36.2.5 Energy saving procedures . 10g36.3 User plane prot
21、ocol procedures 10g37 Xn interface protocol structure . 10g37.1 Xn Control Plane 10g37.2 Xn User Plane . 10g38 Other Xn interface specifications . 11g38.1 NG-RAN Xn interface: Xn layer 1 (TS 38.421). 11g38.2 NG-RAN Xn interface: Xn signalling transport (TS 38.422) . 11g38.3 NG-RAN Xn interface: Xn a
22、pplication protocol (XnAP) (TS 38.423) 11g38.4 NG-RAN Xn interface: Xn data transport (TS 38.424) 11g3ETSI ETSI TS 138 420 V15.0.0 (2018-07)43GPP TS 38.420 version 15.0.0 Release 158.5 NG-RAN Xn interface: NR user plane protocol (TS 38.425) 11g38.6 NG-RAN Xn interface: PDU Session User Plane Protoco
23、l (TS 38.415) . 11g38.7 Summary of NG-RAN Xn interface Technical Specifications . 11g3Annex A (informative): Change history . 13g3History 14g3ETSI ETSI TS 138 420 V15.0.0 (2018-07)53GPP TS 38.420 version 15.0.0 Release 15Foreword This Technical Specification has been produced by the 3rd Generation P
24、artnership Project (3GPP). The contents of the present document are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an
25、increase in version number as follows: Version x.y.z where: x the first digit: 1 presented to TSG for information; 2 presented to TSG for approval; 3 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of substance, i.e. technical enhanc
26、ements, corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the document. ETSI ETSI TS 138 420 V15.0.0 (2018-07)63GPP TS 38.420 version 15.0.0 Release 151 Scope The present document is an introduction to the TSG RAN TS 38.42x series of Te
27、chnical Specifications that define the Xn interface. It is an interface for the interconnection of two NG-RAN nodes within the NG-RAN architecture (TS 38.401 2). 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present docume
28、nt. - References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. - For a specific reference, subsequent revisions do not apply. - For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (in
29、cluding a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document. 1 3GPP TR 21.905: “Vocabulary for 3GPP Specifications“. 2 3GPP TS 38.401: “NG-RAN; Architecture description“. 3 3GPP TS 38.421: “NG-RAN; Xn layer 1“
30、. 4 3GPP TS 38.422: “NG-RAN; Xn signalling transport“. 5 3GPP TS 38.423: “NG-RAN; Xn Application Protocol (XnAP)“. 6 3GPP TS 38.424: “NG-RAN; Xn data transport“. 7 3GPP TS 38.425: “NG-RAN; NR user plane protocol“. 8 3GPP TS 38.300: “NR; Overall Description; Stage 2“. 9 3GPP TS 37.340: “NR; Multi-con
31、nectivity; Overall description; Stage-2“. 10 3GPP TS 38.415: “PDU Session User Plane protocol“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 1 and the following apply. A term defined in the present documen
32、t takes precedence over the definition of the same term, if any, in 3GPP TR 21.905 1. corresponding node: as defined in TS 38.425 7. NG-RAN node: as defined in TS 38.300 8. secondary node: as defined in TS 37.340 9. 3.2 Abbreviations For the purposes of the present document, the abbreviations given
33、in 3GPP TR 21.905 1 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in 3GPP TR 21.905 1. Xn-C Xn Control plane Xn-U Xn User plane ETSI ETSI TS 138 420 V15.0.0 (2018-07)73GPP TS 38.420 version 15.0.0 Relea
34、se 154 General aspects 4.1 Introduction The interface allowing to interconnect NG-RAN nodes with each other is referred to as the Xn interface. 4.2 Xn interface general principles The general principles for the specification of the Xn interface are as follows: - the Xn interface is open; - the Xn in
35、terface supports the exchange of signalling information between two NG-RAN nodes, and the forwarding of PDUs to the respective tunnel endpoints; - from a logical standpoint, the Xn is a point-to-point interface between two NG-RAN nodes. A point-to-point logical interface should be feasible even in t
36、he absence of a physical direct connection between the two NG-RAN nodes. 4.3 Xn interface specification objectives The Xn interface specifications facilitate the following: - inter-connection of NG-RAN nodes supplied by different manufacturers; - support of continuation between NG-RAN nodes of the N
37、G-RAN services offered via the NG interface; - separation of Xn interface Radio Network functionality and Transport Network functionality to facilitate introduction of future technology. 4.4 Xn interface capabilities The Xn interface supports: - procedures to support intra-NG-RAN mobility; - procedu
38、res to support dual connectivity between NG-RAN nodes. 5 Functions of the Xn interface 5.1 General The following clauses describe the functions supported in Xn interface. 5.2 Functions of Xn-C 5.2.1 Xn-C interface management and error handling functions 5.2.1.1 General These functions allow for mana
39、ging of signalling associations between NG-RAN nodes, surveying the Xn interface and recovering from errors. 5.2.1.2 Xn Setup function This function allows for the initial setup of an Xn interface between two NG-RAN nodes, including exchange of application level data. ETSI ETSI TS 138 420 V15.0.0 (2
40、018-07)83GPP TS 38.420 version 15.0.0 Release 155.2.1.3 Error Indication function This function allows the reporting of general error situations on application level. 5.2.1.4 Xn reset function This function allows an NG-RAN node to inform a second NG-RAN node that it has recovered from an abnormal f
41、ailure and that either all or some of the contexts (except the application level data) related to the first node and stored in the second shall be deleted, and the associated resources released. 5.2.1.5 Xn configuration data update function This function allows two NG-RAN nodes to update application
42、 level data at any time. 5.2.1.6 Xn removal function This function allows two NG-RAN nodes to remove the respective Xn interface. 5.2.2 UE mobility management functions 5.2.2.1 Handover preparation function This function allows the exchange of information between source and target NG-RAN nodes in or
43、der to initiate the handover of a certain UE to the target. 5.2.2.2 Handover cancellation function This function allows informing an already prepared target NG-RAN node that a prepared handover will not take place. It allows releasing the resources allocated during a preparation. 5.2.2.3 Retrieve UE
44、 Context function The Retrieve UE context function is used for a NG-RAN node to retrieve UE context from another one. 5.2.2.4 RAN Paging function The RAN paging function allows a NG-RAN node to initiate the paging for a UE in the inactive state. 5.2.2.5 Data Forwarding control function The data forw
45、arding control function allows establishing and releasing transport bearers between source and target NG-RAN nodes for data forwarding. 5.2.3 Dual connectivity function The dual connectivity function enables usage of additional resources in a secondary node in the NG-RAN. 5.2.4 Energy saving functio
46、n This function enables decreasing energy consumption by indication of cell activation/deactivation over the Xn interface. 5.3 Functions of Xn-U 5.3.1 Data transfer function The data transfer function allows the transfer of data between NG-RAN nodes to support dual connectivity or mobility operation
47、. 5.3.2 Flow control function The flow control function enables a NG-RAN node receiving user plane data from a second NG-RAN node to provide feedback information associated with the data flow. ETSI ETSI TS 138 420 V15.0.0 (2018-07)93GPP TS 38.420 version 15.0.0 Release 156 Xn interface procedures 6.
48、1 General The Xn interface supports procedures over the control plane (Xn-C) and user plane (Xn-U). 6.2 Control plane protocol procedures 6.2.1 Mobility management procedures The mobility management procedures are used to manage the UE mobility in Connected or RRC_Inactive modes: - Handover Preparat
49、ion - Handover Cancel - SN Status Transfer - Retrieve UE Context - RAN Paging - Data Forwarding Address Indication - UE Context Release 6.2.2 Dual Connectivity procedures The dual connectivity procedures are used to add, modify and releases resources for the operation of Dual Connectivity: - S-NG-RAN-node Addition Preparation - S-NG-RAN-node Reconfiguration Completion - M-NG-RAN-node initiated S-NG-RAN-node Modification Preparation - S-NG-RAN-node initiated S-NG-RAN-node Modification - M-NG-RAN-node initiated S-NG-RAN-node Release - S-NG-RAN
