1、 ETSI TS 138 401 V15.2.0 (2018-07) 5G; NG-RAN; Architecture description (3GPP TS 38.401 version 15.2.0 Release 15) TECHNICAL SPECIFICATION ETSI ETSI TS 138 401 V15.2.0 (2018-07)13GPP TS 38.401 version 15.2.0 Release 15Reference DTS/TSGR-0338401vf20 Keywords 5G ETSI 650 Route des Lucioles F-06921 Sop
2、hia 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-search The p
3、resent document may be made available in electronic versions and/or in print. The content of any electronic and/or print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any existing or perceived difference in contents between such ve
4、rsions and/or in print, the only prevailing document is the print of the Portable Document Format (PDF) version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the
5、 current status of this and other ETSI documents is available at https:/portal.etsi.org/TB/ETSIDeliverableStatus.aspx If you find errors in the present document, please send your comment to one of the following services: https:/portal.etsi.org/People/CommiteeSupportStaff.aspx Copyright Notification
6、No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm except as authorized by written permission of ETSI. The content of the PDF version shall not be modified without the written authorization of ETSI. The copyright and the
7、foregoing restriction extend to reproduction in all media. ETSI 2018. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTMand the ETSI logo are trademarks of ETSI registered for the benefit of its Members. 3GPPTM and LTETMare trademarks of ETSI registered for the benefit of its Members and of the 3GPP O
8、rganizational 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 138 401 V15.2.0 (2018-07)23GPP TS 38.401 version 15.2.0 Release 15Intellectual Property Rights Essential patents IPRs essentia
9、l 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 potentiall
10、y 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. No guar
11、antee 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 and/or re
12、gistered by their owners. ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does not constitute an endorsement by ETSI of pro
13、ducts, 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 identities or GSM
14、 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 not“, “shou
15、ld“, “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 citation. ET
16、SI ETSI TS 138 401 V15.2.0 (2018-07)33GPP TS 38.401 version 15.2.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 5g31 Scope 6g32 References 6g33 Definitions and abbreviations . 6g33.1 Definitions 6g33.2 Abbreviations . 7g34 General principles
17、8g35 General architecture . 8g35.1 General . 8g35.2 User plane . 8g35.3 Control plane 9g36 NG-RAN architecture. 10g36.1 Overview 10g36.1.1 Overall Architecture of NG-RAN . 10g36.1.2 Overall architecture for separation of gNB-CU-CP and gNB-CU-UP . 11g36.2 NG-RAN identifiers . 11g36.2.1 Principle of h
18、andling Application Protocol Identities . 11g36.2.2 gNB-DU ID 13g36.3 Transport addresses 13g36.4 UE associations in NG-RAN Node 13g37 NG-RAN functions description 14g37.0 General . 14g37.1 Void 14g38 Overall procedures in gNB-CU/gNB-DU Architecture . 14g38.1 UE Initial Access 14g38.2 Intra-gNB-CU M
19、obility 16g38.2.1 Intra-NR Mobility . 16g38.2.1.1 Inter-gNB-DU Mobility 16g38.2.1.2 Intra-gNB-DU handover . 17g38.2.2 EN-DC Mobility . 17g38.2.2.1 Inter-gNB-DU Mobility using MCG SRB 17g38.2.2.2 Inter-gNB-DU Mobility using SCG SRB . 19g38.3 Mechanism of centralized retransmission of lost PDUs . 19g3
20、8.3.1 Centralized Retransmission in Intra gNB-CU Cases 19g38.4 Multi-Connectivity operation . 20g38.4.1 Secondary Node Addition . 20g38.4.1.1 EN-DC 20g38.4.2 Secondary Node Release (MN/SN initiated) 21g38.4.2.1 EN-DC 21g38.5 F1 Startup and cells activation . 22g38.6 RRC state transition 23g38.6.1 RR
21、C connected to RRC inactive. 23g38.6.2 RRC inactive to other states 23g38.7 RRC connection reestablishment . 25g38.8 Multiple TNLAs for F1-C 26g38.9 Overall procedures involving E1 and F1 27g38.9.1 UE Initial Access 27g38.9.2 Bearer context setup over F1-U 28g38.9.3 Bearer context release over F1-U
22、. 29g3ETSI ETSI TS 138 401 V15.2.0 (2018-07)43GPP TS 38.401 version 15.2.0 Release 158.9.3.1 gNB-CU-CP initiated bearer context release 29g38.9.3.2 gNB-CU-UP initiated bearer context release 29g38.9.4 Inter-gNB handover involving gNB-CU-UP change 30g38.9.5 Change of gNB-CU-UP 31g38.9.6 RRC State tra
23、nsition . 32g38.9.6.1 RRC Connected to RRC Inactive 32g38.9.6.2 RRC Inactive to other states 33g39 Synchronization 35g39.1 gNB Synchronization . 35g310 NG-RAN interfaces 35g310.1 NG interface . 35g310.2 Xn interface 35g310.3 F1 interface . 35g310.4 E1 interface 36g3Annex Ag23395(informative): Deploy
24、ment scenarios of gNB/en-gNB . 37g3Annex B (informative): Change History 38g3History 39g3ETSI ETSI TS 138 401 V15.2.0 (2018-07)53GPP TS 38.401 version 15.2.0 Release 15Foreword This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The contents of the present
25、 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 increase in version number as follows: Version x.y.z w
26、here: 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 enhancements, corrections, updates, etc. z the third digit i
27、s incremented when editorial only changes have been incorporated in the document. ETSI ETSI TS 138 401 V15.2.0 (2018-07)63GPP TS 38.401 version 15.2.0 Release 151 Scope The present document describes the overall architecture of the NG-RAN, including interfaces NG, Xn and F1 interfaces and their inte
28、raction with the radio interface. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. - References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
29、- 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 (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release a
30、s the present document. 1 3GPP TR 21.905: “Vocabulary for 3GPP Specifications“. 2 3GPP TS 38.300: “NR; Overall description; Stage-2“. 3 3GPP TS 23.501: “System Architecture for the 5G System“. 4 3GPP TS 38.473: “NG-RAN; F1 application protocol (F1AP)“. 5 3GPP TS 38.414: “NG-RAN; NG data transport“.
31、6 3GPP TS 38.424: “NG-RAN; Xn data transport“. 7 3GPP TS 38.474: “NG-RAN; F1 data transport“. 8 ITU-T Recommendation G.823 (2000-03): “The control of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy“. 9 ITU-T Recommendation G.824 (2000-03): “The control of jitte
32、r and wander within digital networks which are based on the 1544 kbit/s hierarchy“. 10 ITU-T Recommendation G.825 (2001-08): “The control of jitter and wander within digital networks which are based on the synchronous digital hierarchy (SDH)“. 11 ITU-T Recommendation G.8261/Y.1361 (2008-04): “Timing
33、 and Synchronization aspects in Packet networks“. 12 3GPP TS 37.340: “NR; Multi-connectivity; Overall description; Stage-2“. 13 3GPP TS 33.501: “Security Architecture and Procedures for 5G System“. 14 3GPP TS 38.410: “NG-RAN; NG general aspect and principles“. 15 3GPP TS 38.420: “NG-RAN; Xn general
34、aspects and principles“ 16 3GPP TS 38.470: “NG-RAN; F1 general aspects and principles“. 17 3GPP TS 38.460: “NG-RAN; E1 general aspects and principles“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given in TR 21.905 1 and the fol
35、lowing apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 1. ETSI ETSI TS 138 401 V15.2.0 (2018-07)73GPP TS 38.401 version 15.2.0 Release 15en-gNB: as defined in TS 37.340 12. gNB: as defined in TS 38.300 2. gNB Central Unit (gNB
36、-CU): a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected with the gNB-DU. gNB Distributed Unit (gNB-DU): a logical node hosting RLC, MAC and PHY la
37、yers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-DU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected with the gNB-CU. gNB-CU-Control Plane (gNB-CU-CP): a logical node hosting the RRC and the
38、 control plane part of the PDCP protocol of the gNB-CU for an en-gNB or a gNB. The gNB-CU-CP terminates the E1 interface connected with the gNB-CU-UP and the F1-C interface connected with the gNB-DU. gNB-CU-User Plane (gNB-CU-UP): a logical node hosting the user plane part of the PDCP protocol of th
39、e gNB-CU for an en-gNB, and the user plane part of the PDCP protocol and the SDAP protocol of the gNB-CU for a gNB. The gNB-CU-UP terminates the E1 interface connected with the gNB-CU-CP and the F1-U interface connected with the gNB-DU. NG-RAN node: as defined in TS 38.300 2. PDU Session Resource: T
40、his term is used for specification of NG, Xn, and E1 interfaces. It denotes NG-RAN interface and radio resources provided to support a PDU Session. 3.2 Abbreviations For the purposes of the present document, the terms and definitions given in TR 21.905 1 and the following apply. A term defined in th
41、e present document takes precedence over the definition of the same term, if any, in TR 21.905 1. 5GC 5G Core Network AMF Access and Mobility Management Function AP Application Protocol AS Access Stratum CM Connection Management CMAS Commercial Mobile Alert Service ETWS Earthquake and Tsunami Warnin
42、g System F1-U F1 User plane interface F1-C F1 Control plane interface F1AP F1 Application Protocol FDD Frequency Division Duplex GTP-U GPRS Tunnelling Protocol IP Internet Protocol NAS Non-Access Stratum O - A gNB may consist of a gNB-CU-CP, multiple gNB-CU-UPs and multiple gNB-DUs; - The gNB-CU-CP
43、is connected to the gNB-DU through the F1-C interface; - The gNB-CU-UP is connected to the gNB-DU through the F1-U interface; - The gNB-CU-UP is connected to the gNB-CU-CP through the E1 interface; - One gNB-DU is connected to only one gNB-CU-CP; - One gNB-CU-UP is connected to only one gNB-CU-CP; N
44、OTE 1: For resiliency, a gNB-DU and/or a gNB-CU-UP may be connected to multiple gNB-CU-CPs by appropriate implementation. - One gNB-DU can be connected to multiple gNB-CU-UPs under the control of the same gNB-CU-CP; - One gNB-CU-UP can be connected to multiple DUs under the control of the same gNB-C
45、U-CP; NOTE 2: The connectivity between a gNB-CU-UP and a gNB-DU is established by the gNB-CU-CP using Bearer Context Management functions. NOTE 3: The gNB-CU-CP selects the appropriate gNB-CU-UP(s) for the requested services for the UE. NOTE 4: Data forwarding between gNB-CU-UPs during intra-gNB-CU-
46、CP handover within a gNB may be supported by Xn-U. 6.2 NG-RAN identifiers 6.2.1 Principle of handling Application Protocol Identities An Application Protocol Identity (AP ID) is allocated when a new UE-associated logical connection is created in either an NG-RAN node or an AMF. An AP ID shall unique
47、ly identify a logical connection associated to a UE over the NG ETSI ETSI TS 138 401 V15.2.0 (2018-07)123GPP TS 38.401 version 15.2.0 Release 15interface or Xn interface within a node (NG-RAN node or AMF) or over the F1 interface or over the E1 interface. Upon receipt of a message that has a new AP
48、ID from the sending node, the receiving node shall store the AP ID of the sending node for the duration of the logical connection. The receiving node shall assign the AP ID to be used to identify the logical connection associated to the UE and include it as well as the previously received new AP ID
49、from the sending node, in the first returned message to the sending node. In all subsequent messages to and from sending node, both AP IDs of sending node and receiving node shall be included. The definitions of AP IDs as used on NG interface or Xn interface or F1 interface or E1 interface are shown below: RAN UE NGAP ID: A RAN UE NGAP ID shall be allocated so as to uniquely identify the UE over the NG interface within an gNB. When an AMF receives an RAN UE NGAP ID it shall store it for the duration of the UE-associated logical N
