1、 ETSI TS 136 425 V15.0.0 (2018-07) Universal Mobile Telecommunications System (UMTS); LTE; Evolved Universal Terrestrial Radio Access Network (E-UTRAN); X2 interface user plane protocol (3GPP TS 36.425 version 15.0.0 Release 15) TECHNICAL SPECIFICATION ETSI ETSI TS 136 425 V15.0.0 (2018-07)13GPP TS
2、36.425 version 15.0.0 Release 15Reference RTS/TSGR-0336425vf00 Keywords LTE,UMTS ETSI 650 Route des Lucioles F-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 Grass
3、e (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org/standards-search The present 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 with
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9、5 V15.0.0 (2018-07)23GPP TS 36.425 version 15.0.0 Release 15Intellectual Property Rights Essential patents IPRs 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 memb
10、ers and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially 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
11、.org/). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. 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
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13、 and/or tradename. Mention of those trademarks in the present document does not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks. Foreword This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP). T
14、he present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities 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 un
15、der http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall“, “shall not“, “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 expre
16、ssion of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TS 136 425 V15.0.0 (2018-07)33GPP TS 36.425 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope
17、 5g32 References 5g33 Definitions, symbols and abbreviations . 5g33.1 Definitions 5g33.2 Abbreviations . 5g34 General . 6g34.1 General aspects . 6g35 X2 user plane protocol . 7g35.1 General . 7g35.2 X2 user plane protocol layer services . 7g35.3 Services expected from the X2 Transport Network Layer
18、. 7g35.4 Elementary procedures . 8g35.4.1 Transfer of Downlink User Data . 8g35.4.1.1 Successful operation 8g35.4.1.2 Unsuccessful operation . 8g35.4.2 Downlink Data Delivery Status 8g35.4.2.1 Successful operation 8g35.4.2.2 Unsuccessful operation . 9g35.5 Elements for the X2 user plane protocol 10g
19、35.5.1 General 10g35.5.2 Frame format for the X2 user plane protocol 11g35.5.2.1 DL USER DATA (PDU Type 0) 11g35.5.2.2 DL DATA DELIVERY STATUS (PDU Type 1) . 12g35.5.2.3 DL DATA DELIVERY STATUS EXTENDED (PDU Type 2). 12g35.5.2.4 DL USER DATA EXTENDED (PDU Type 3) 13g35.5.3 Coding of information elem
20、ents in frames . 14g35.5.3.1 PDU Type . 14g35.5.3.2 Spare . 14g35.5.3.3 X2-U Sequence Number . 14g35.5.3.4 Lost Packet Report 14g35.5.3.5 Final Frame Indication 14g35.5.3.6 Highest successfully delivered PDCP Sequence Number . 14g35.5.3.7 Desired buffer size for the E-RAB 14g35.5.3.8 Minimum desired
21、 buffer size for the UE . 15g35.5.3.9 Number of lost X2-U Sequence Number ranges reported . 15g35.5.3.10 Start of lost X2-U Sequence Number range 15g35.5.3.11 End of lost X2-U Sequence Number range . 15g35.5.3.12 Padding . 15g35.5.3.13 Highest successfully delivered PDCP Sequence Number Extended . 1
22、5g35.5.3.14 Start of lost X2-U Sequence Number range Extended 15g35.5.3.15 End of lost X2-U Sequence Number range Extended . 15g35.5.3.16 X2-U Sequence Number Extended . 16g35.5.4 Timers . 16g35.6 Handling of unknown, unforeseen and erroneous protocol data 16g3Annex A (informative): Change history .
23、 17g3History 18g3ETSI ETSI TS 136 425 V15.0.0 (2018-07)43GPP TS 36.425 version 15.0.0 Release 15Foreword This Technical Specification has been produced by the 3rdGeneration Partnership Project (3GPP). The contents of the present document are subject to continuing work within the TSG and may change f
24、ollowing 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 where: x the first digit: 1 presented to TSG for information; 2 presented
25、 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 is incremented when editorial only changes have been incorporated in the
26、document. ETSI ETSI TS 136 425 V15.0.0 (2018-07)53GPP TS 36.425 version 15.0.0 Release 151 Scope The present document specifies the X2 user plane protocol being used over the X2 interface. 2 References The following documents contain provisions which, through reference in this text, constitute provi
27、sions of the present document. - 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 refer
28、ence 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 as the present document. 1 3GPP TR 21.905: “Vocabulary for 3GPP Specifications“. 2 3GPP TS 36.300: “Evolved Universal Terrestrial Radio Access (E-
29、UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2“. 3 3GPP TS 29.281: “General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U)“. 3 Definitions, symbols and abbreviations 3.1 Definitions For the purposes of the present document, t
30、he terms and definitions given in TR 21.905 1 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 1. Master eNB: as defined in TS 36.300 2. Secondary eNB: as defined in TS 36.300 2. Split bearer: as defined in TS
31、 36.300 2. 3.2 Abbreviations For the purposes of the present document, the abbreviations given in 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 TR 21.905 1. DC Dual Connectivity DL Downli
32、nk E-RAB E-UTRAN Radio Access Bearer MeNB Master eNB SeNB Secondary eNBUL Uplink UP User Plane X2 UP X2 User Plane ETSI ETSI TS 136 425 V15.0.0 (2018-07)63GPP TS 36.425 version 15.0.0 Release 154 General 4.1 General aspects The X2 user plane (X2 UP) protocol is located in the User Plane of the Radio
33、 Network layer over the X2 interface. The X2 UP protocol is used to convey control information related to the user data flow management of E-RABs. Each X2 UP protocol instance is associated to one E-RAB only. This version of the present document defines the X2 UP protocol in the context of dual conn
34、ectivity only, more specifically, only for X2 user data bearers setup for E-RABs configured with the split bearer option. If configured, X2 UP protocol instances exist at the eNBs between which the X2 user data bearers are setup, specifically for dual connectivity between the MeNB and the SeNB. NOTE
35、: X2 user data bearers may be setup for data forwarding purposes during X2 HO or during DC related mobility, however, these X2 user data bearers do not require the execution of any additional E-RAB related UP protocol functions related to an X2 UP protocol instance. In this version of the present do
36、cument, X2 UP protocol data is conveyed by GTP-U protocol means, more specifically, by means of the “RAN Container“ GTP-U extension header as defined in TS 29.281 3. ETSI ETSI TS 136 425 V15.0.0 (2018-07)73GPP TS 36.425 version 15.0.0 Release 155 X2 user plane protocol 5.1 General The X2 UP protocol
37、 layer is using services of the transport network layer in order to allow flow control of user data packets transferred over the X2 interface. 5.2 X2 user plane protocol layer services The following functions are provided by the X2 UP protocol: - Provision of X2 UP specific sequence number informati
38、on for user data transferred from the MeNB to the SeNB for a specific E-RAB configured with the split bearer option; - Information of successful in sequence delivery of PDCP PDUs to the UE from SeNB for user data associated with a specific E-RAB configured with the split bearer option; - Information
39、 of PDCP PDUs that were not delivered to the UE; - Information of the currently desired buffer size at the SeNB for transmitting to the UE user data associated with a specific E-RAB configured with the split bearer option; - Information of the currently minimum desired buffer size at the SeNB for tr
40、ansmitting to the UE user data associated with all E-RABs configured with the split bearer option. 5.3 Services expected from the X2 Transport Network Layer The X2 user plane protocol layer expects the following services from the Transport Network Layer: - Transfer of user data. ETSI ETSI TS 136 425
41、 V15.0.0 (2018-07)83GPP TS 36.425 version 15.0.0 Release 155.4 Elementary procedures 5.4.1 Transfer of Downlink User Data 5.4.1.1 Successful operation The purpose of the Transfer of Downlink User Data procedure is to provide X2-U specific sequence number information at the transfer of user data carr
42、ying a DL PDCP PDU from the MeNB to the SeNB via the X2-U interface. An X2 user plane instance making use of the Transfer of Downlink User Data procedure is associated to a single E-RAB only. The Transfer of Downlink User Data procedure is invoked whenever user data for that particular E-RAB needs t
43、o be sent across the X2-U interface. The MeNB shall assign consecutive X2-U sequence numbers to each transferred X2-U packet. The SeNB shall detect whether an X2-U packet was lost and memorise the respective sequence number after it has declared the respective X2-U packet as being “lost“. The SeNB s
44、hall transfer the remaining PDCP PDUs towards the UE and memorise the highest PDCP PDU sequence number of the PDCP PDU that was successfully delivered in sequence towards the UE. NOTE: The Transfer of Downlink User Data procedure and the associated feedback of lost X2-U packets assist the MeNB in av
45、oiding PDCP HFN de-synchronisation. If an E-UTRAN deployment decides to not use the Transfer of Downlink User Data procedure, PDCP HFN synchronization should be ensured by other means. uni004Duni0065uni004Euni0042 uni0053uni0065uni004Euni0042uni0044uni004Cuni0020uni0055uni0053uni0045uni0052uni0020un
46、i0044uni0041uni0054uni0041Figure 5.4.1.1-1: Successful Transfer of Downlink User Data 5.4.1.2 Unsuccessful operation Void. 5.4.2 Downlink Data Delivery Status 5.4.2.1 Successful operation The purpose of the Downlink Data Delivery Status procedure is to provide feedback from the SeNB to the MeNB to a
47、llow the MeNB to control the downlink user data flow via the SeNB for the respective E-RAB. The SeNB may also transfer uplink user data for the concerned E-RAB to the MeNB together with a DL DATA DELIVERY STATUS frame within the same GTP-U PDU. When the SeNB decides to trigger the Feedback for Downl
48、ink Data Delivery procedure it shall report: a) the highest PDCP PDU sequence number successfully delivered in sequence to the UE among those PDCP PDUs received from the MeNB; b) the desired buffer size in bytes for the concerned E-RAB; c) the minimum desired buffer size in bytes for the UE; d) the
49、X2-U packets that were declared as being “lost“ by the SeNB and have not yet been reported to the MeNB within the DL DATA DELIVERY STATUS frame. NOTE: If an E-UTRAN deployment has decided not to use the Transfer of Downlink User Data procedure, d) above is not applicable. ETSI ETSI TS 136 425 V15.0.0 (2018-07)93GPP TS 36.425 version 15.0.0 Release 15The DL DATA DELIVERY STATUS frame shall also include an indication whether the frame is the last DL status report received in the course of releasing a bearer from the SeNB. When receiving such indication, if
