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Service Function Chaining                              Sunil Kumar Sinha
Internet-Draft                              Infinite Computing Solutions
Intended status: Informational                            Amardeep Sinha
Expires: December 9, 2018                  Reliance Jio Infocomm Limited
                                                             Amit Mishra
                                                          Varsa Networks
                                                     Yogesh Chandeshware
                                                                Mavenier
                                                           June 10, 2018


                5G System Split Bearer for Dual-Access
              draft-sfc-sinha-5g-split-bearer-dual-access-00


Abstract

   This document attempts the case for new work that needs to be
   developed for 5G users to improve faster download and upload of
   user's data in a scenario of dual-access outlining the poor radio
   coverage issues. This document also outlines the faster user data
   mechanisum accompanying dual access capabilities of 5G user device
   via split bearer in case of a poor coverage.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on December 9, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.





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Table of Contents:

   1. Introduction...................................................2
   2. Conventions and Terminology....................................2
   3. User data flow for Dual Connectivity for Dual Access and
      problem statement..............................................2
      3.1 5G System Architecture.....................................2
      3.2 QoS........................................................4
      3.3 Dual Connectivity..........................................5
      3.4 Problem Statement..........................................5
   4. Proposal of Split Bearer for dual access.......................5
   5. IANA Considerations............................................7
   6. Security Considerations........................................7
   7. Privacy Considerations ........................................7
   8. Acknowledgements...............................................7
   9. References.....................................................7
      9.1 Normative References.......................................7
      9.2 Informative References.....................................8
   Authors' Addresses................................................9


1. Introduction

   5G system has been evolved to serve the user in more efficient way of
   meeting higher download and upload of user data, 5G Users accessing
   the network via wireline and wireless, in addition to this
   Residential Gateway RG and IoT support is also defined. Access and
   user experience is challenging for poor radio coverage (for both
   wi-fi and RAN) and the proposal in this document addresses the
   problem of poor coverage on either 3GPP or non-3GPP access with UE in
   dual-access mode.

2.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3. User data flow for Dual Connectivity for Dual Access and problem
   statement

3.1 5G System Architecture

   A simplified 5G System architecture shown in Figure-1 in the case of
   UE in non-roaming scenario with RAN access(3GPP).

   User data of 5G system is delivered to user from Service or data
   network via interface N6 and N3 to UE.





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                    +-----------------------------+
                    | +-----------------+         |
                    | |                 |N8       |N15
       +------+     | | +----+  N13  +-----+      |
       | NSSF |---+ | | |AUSF|-------| UDM |      |
       +------+   | | | +----+       +-----+      |
                  | | |   |             |         |
               N22| | |   |N12          |N10   +-----+  N5  +----+
                  | | | +-+             |      | PCF |------| AF |
                  | | | |               |      +-----+      +----+
                  | | | |               |         |
                 +-------+      N11   +---+   N7  |
                 |  AMF  |------------|SMF|-------+
                 +-------+            +---+
                     |                  |
                     |N2                |N4
                     |                  |
                     |                  |
         Uu       +-----+     N3      +---+   N6   +-------------+
  UE--------------| RAN |-------------|UPF|--------| Service N/W |
                  +-----+             +---+        +-------------+

        Figure 1 : Simplified 5G System Architecture for RAN access

   For the clarity in the current document proposal, multiple node/
   function like UDSF, NRF, and interfaces N9, N14 are not shown.

   5G System supporting UE access to the network function and services
   via non-3GPP is shown in Figure-2. An example of such access are
   like WLAN or Wi-Fi. The N3IWF interface connect UE with 5G core
   network via N2 and N3 interface.

                    +-----------------------------+
                    | +-----------------+         |
                    | |                 |N8       |N15
       +------+     | | +----+  N13  +-----+      |
       | NSSF |---+ | | |AUSF|-------| UDM |      |
       +------+   | | | +----+       +-----+      |
                  | | |   |             |         |
               N22| | |   |N12          |N10   +-----+  N5  +----+
                  | | | +-+             |      | PCF |------| AF |
                  | | | |               |      +-----+      +----+
                  | | | |               |         |
                 +-------+      N11   +---+   N7  |
                 |  AMF  |------------|SMF|-------+
                 +-------+            +---+
                     |                  |
                     |N2                |N4
                     |                  |
                     |                  |
     Y1  +--+  Y2 +-----+     N3      +---+   N6   +-------------+
  UE-----|AP|-----|N3IWF|-------------|UPF|--------| Service N/W |
         +--+     +-----+             +---+        +-------------+

   Figure 2 : Simplified 5G System Architecture for Wi-Fi access



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   A complete architectural diagram of 5G System catering to both
   access type being supported by UE is shown in Figure 3.

           +--------------------------------------------------------+
           |             +----------------------------+             |
           |             | +------------------+       |             |
           |             | |                  |       |             |
           |             | |                  |N8     |N15          |
           |             | |                  |       |             |
           | +------+    | | +------+  N13  +---+     |             |
           | | NSSF |--+ | | | AUSF |-------|UDM|     |             |
           | +------+  | | | +------+       +---+     |             |
           |           | | |     |            |       |             |
           |           | | |     |            |       |             |
         N3|        N22| | |     |N12      N10|     +---+  N5  +--+ |
           |           | | | +---+            |     |PCF|------|AF| |
           |           | | | |                |     +---+      +--+ |
           |           | | | |                |       |             |
        +-----+      +---------+           +-----+    |             |
        | RAN |------|   AMF   |-----------| SMF |----+             |
        +-----+  N2  +---------+    N11    +-----+   N7             |
           |             |                    |                     |
  +--+  Uu |             |                    |                     |
  |  |-----+             |N2                  |N4                   |
  |UE|                   |                    |                     |
  |  |-----+             |                    |                     |
  +--+  Y1 |  +----------+          +---------+                     |
           |  |                     |                               |
           |  |                     |                               |
        +--------+       N3      +-----+  N6  +-------------+       |
        |AP+N3IWF|---------------| UPF |------| Service N/W |       |
        +--------+               +-----+      +-------------+       |
                                    |                               |
                                    +-------------------------------+


      Figure 3 : Simplified 5G System Architecture for Multi access


3.2 QoS

   QFI is defined as Qos Flow ID is a identity to QoS flow in the 5G
   system. All data traffic within a PDU session are each labelled or
   identified by QFI, implies same QFI labelled data flow will receives
   same traffic forwarding treatment like scheduling, priority, etc.

   QoS /Data flow is via N3(and N3 and N9) interface, being encapsulated
   end-to-end. This flow is controlled by SMF, who provides QoS profile
   during session establishment to R(AN) and provide the PDR to the UPF.

   Please Note that like 4G system, default QoS flow is applied to each
   PDU session and retain till lifetime span of connectivity. In case
   of non-3GPP access QFI is delivered to N3IWF entity (or NG-RAN) for
   every time User Plane of the PDU session is established, modified or
   activated.


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3.3 Dual Connectivity

   Dual connectivity (DC) functionality support the network to make use
   of additional radio resource to achieve required throughput in
   downlink and uplink of user data. This was introduced in 4G system
   support 5G data speed by addition of dual connectivity of UE with
   eNBs, master eNB and secondary eNB and /or eNodeB in congestion with
   gNB. This is achieved by addition of secondary eNodeB to the Master
   eNodeB. Master eNB has full control to add, delete and HO(handover)
   of eNodeBs as and when needed.[20160157293]

3.4 Problem Statement

   Problem statement: Inspite of dual access 5G users radio condition
   capabilities degrade on either of the access types and the
   associated user experience on that access type becomes a challenge.

4. Proposal of Split Bearer for dual access

   The solution proposed in this document to solve the problem of
   degrade radio condition on the either of the access type at UE and
   bearer offloading to other access-type.

   Bearer split among RAN and Wifi referring to Fig-4. Trigger for split
   bearer of bearer can originate from other of access type RAN or wifi.

   - In the example given in figure-4 there is a degrade in radio
     condition at RAN access of user. And at the same time 5G user also
     have wi-fi access registered.

   - Based on measurement report from UE, gNB (RAN) take decision for
     partial Handover. gNB asked for UECapabilitys to check availability
     of other access type.

   - Taking inputs on UECapabilities response about the availability of
     other access type, gNB process for Split bearer with other access
     type

   - gNB(RAN) triggers split bearer request for Wi-Fi access to AMF
     and also includes user data traffic template FILTER.

   FILTER:
     FILTER is a user data delivery template defined by NG-RAN for the
     5G-core UPF to implement and execute, without super imposing on the
     PCC rule.

   - If offload of complete user data traffic is needed, then FILTER
      value MUST be empty/NULL.




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     +--+           +-----+    +-----+    +---+     +---+   +---+
     |UE|           | gNB |    |N3IWF|    |AMF|     |SMF|   |UPF|
     +--+           +-----+    +-----+    +---+     +---+   +---+
       |               |          |         |        |         |
       |<==User Data==>|<==============User Data==============>|
       |               |          |         |        |         |
       |  Measurement Control     |         |        |         |
       |<--------------|          |         |        |         |
       |               |          |         |        |         |
       | Measurement   |          |         |        |         |
       |-------------->|          |         |        |         |
       | Report        |          |         |        |         |
       |          +-------------+ |         |        |         |
       |          | HO Decision | |         |        |         |
       |          +-------------+ |         |        |         |
       |               |          |         |        |         |
       |UEAccessCapability        |         |        |         |
       |<--------------|          |         |        |         |
       |               |          |         |        |         |
       |UE-Wifi Access Report     |         |        |         |
       |-------------->|          |         |        |         |
       |               |          |         |        |         |
       |    +-------------+       |         |        |         |
       |    |SPLIT Bearer |       |         |        |         |
       |    |Dual Access  |       |         |        |         |
       |    +-------------+       |         |        |         |
       |               |          |         |        |         |
       |              Split-Bearer Request to Wifi   |         |
       |               |------------------->|        |         |
       |               | (FILTER) |         |        |         |
       |               |          |         |        |         |
       |               |    +---------------------+  |         |
       |               |    |HO procedure to N3IWF|  |         |
       |               |    |  + FILTER           |  |         |
       |               |    +---------------------+  |         |
       |               |          |         |        |         |
       |               |          |     +-------------------------+
       |               |          |     |Bearer Update + FILTER   |
       |               |          |     +-------------------------+
       |<WiFi Connectionprocedure>|         |        |         |
       |               |          |         |        |         |
       |<=Split Bearer with Wifi=>|<========Data==============>|
       |               |          |         |        |         |
       |<=Split Beare=>|<========Data=========================>|
       |   with RAN    |          |         |        |         |

   Figure 4 : Bearer Offloading Dual-Connectivity with dual access

   - If split of user data traffic is needed, then FILTER SHOULD have
     required template according to which partial user data traffic is
     split between RAN and Wi-Fi by UPF on N3 interface.


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5. IANA Considerations

   None.

6. Security Considerations

   Security considerations related to the 5G systems are discussed in
   [NGMN].  Due to the request for intrinsic realization of security
   such aspects have to be considered by design for architecture and
   protocols.

   Especially as a joint usage of resources and network functions by
   different separate logical network slices (e.g. in terms of virtual
   network functions) seems to be inevitable in the framework of 5G the
   need for strong security measures in such an environment is a major
   challenge.

7. Privacy Considerations

   Support of full privacy of the users (customers and tenants / end
   service providers) is a basic feature of the next generation trusted
   and reliable communications offering system.  Such a high degree of
   ensured privacy shall be reflected in the proposed architecture and
   protocol solutions.

   Especially as Identifiers and mapping of locators to them are
   addressed some privacy concerns arise.  Mobility solutions tend to
   expose unique identifiers.  A solution inside the mobile network
   exposes these identifiers to the network operator, which is not a big
   deal since the network operator already has information about the
   device's location.  In contrast, an IP level solution exposes both
   the identifiers and the locations at the IP layer.  That means that
   web sites, for example, can now track the device's successive
   locations by watching the IP address.  Solutions such as transporting
   the identifiers not as part of the IP header should be considered.

8.  Acknowledgements

   This work has been partially performed in the framework of the
   cooperation Config.  Contributions of the project partners are
   gratefully acknowledged.  The project consortium is not liable for
   any use that may be made of any of the information contained therein.

   Comments, constructive critisms from Karthik Palaniswamy and
   Nagesh V. J. are respectfully acknowledged.

9.  References

9.1.  Normative References


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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

9.2.  Informative References


   [20160157293]
              "Method to Provide Dual Connectivity Using LTE Master
               eNodeB and Wi-Fi Based Secondary eNodeB", June,2016.

   [TS23.228]
              "IP Multimedia Subsystem (IMS)", March 2018.

   [TR38.801]
              "Study on new radio access technology: Radio
               access architecture and interfaces", March 2017.

   [TR23.793]
              "Study on Access Traffic Steering, Switch and Splitting
               support in the 5G system architecture.", April 2018.

   [TR23.793]
              "Study on Access Traffic Steering, Switch and Splitting
               support in the 5G system architecture.", April 2018.

   [ETSI GR NGP 004]
              "Next Generation Protocol (NGP):Evolved Architecture for
               mobility using. Identity Oriented Networks.",January 2018

   [ETSI GR NGP 001]
              "Next Generation Protocol (NGP); Scenario Definitions".
               ,May 2017

   [TS23.501]
              "3GPP TS23.501, System Architecture for the 5G System
              (Release 15)", March 2018.

   [TS23.502]
              "3Procedures for the 5G System", March 2018.

   [TS36.300]
              "3GPP TS36.300, Evolved Universal Terrestrial Radio Access
               (E-UTRA) and Evolved Universal Terrestrial Radio Access
               Network (E-UTRAN); Overall description", March 2018.

   [NGMN]
              NGMN Alliance, "NGMN White Paper", February 2015.




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Authors' Addresses

   Sunil Kumar Sinha
   FF-01, Rainbow Residency,
   Green Glan layout,
   Bellandur, Bangalore
   Karnataka, India

   Email: sunilkumarsinha9@gmail.com


   Amardeep Sinha
   C-1003, Yashodeep Heights,
   Sec-29C, Airoli,
   Navi-Mumbai, Maharashtra, India

   Email: sinha.amardeep@gmail.com


   Amit Mishra
   Flat No: 208, 16th Block,
   Sun City Appartments,
   Iblur Junction, Sarjapur Signal,
   Bengaluru, India

   Email: amit.j.mishra@gmail.com


   Yogesh Chandeshware
   Shasi Nivas, 1st Street , F main,
   Vijaya Vank Colony Extn,
   Banaswadi, Bangalore
   Karnataka,
   India

   Email: yogeshjc017@gmail.com















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