Internet DRAFT - draft-sfc-sinha-5g-bearer-dc-ran
draft-sfc-sinha-5g-bearer-dc-ran
Service Function Chaining Sunil Kumar Sinha
Internet-Draft Infinite Computing Solutions
Intended status: Informational Amardeep Sinha
Expires: December 7, 2018 Reliance Jio Infocomm Limited
Dharmendra Dwivedi
Ericsson
Harsh Vardhan Singh Chauhan
Nokia
June 8, 2018
5G-System Bearer Offloading for Dual Connectivity for RAN
draft-sfc-sinha-5g-bearer-dc-ran-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 the
user's data in a scenario of dual-connectivity 3GPP access outlining
the poor radio coverage issues. This document also outlines the
faster user data mechanism accompanying 3GPP access of 5G user
device via bearer offloading in case of a poor coverage.
Status of This Memo
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This Internet-Draft will expire on December 7, 2018
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Table of Contents:
1. Introduction...................................................2
2. Conventions and Terminology....................................2
3. User data flow for Dual Connectivity for 3GPP access and
problem statement..............................................2
3.1 5G System architecture.....................................2
3.2 QoS........................................................3
3.3 Dual Connectivity..........................................3
3.4 Problem Statement..........................................4
4. Proposal of Bearer Offloading Dual-Connectivity with 3GPP
access ........................................................4
5. IANA Considerations............................................6
6. Security Considerations........................................6
7. Privacy Considerations ........................................6
8. Acknowledgements...............................................6
9. References.....................................................7
9.1 Normative References.......................................7
9.2 Informative References.....................................7
Authors' Addresses................................................8
1. Introduction
5G system has been evolved to serve the user in more efficient way
of meeting higher download and upload of user data for 5G Users
accessing the network via wireline and wireless, in addition to
Residential Gateway RG and IoT support. In 5G system Access and
user experience is challenging for poor radio coverage (for both
wi-fi and RAN) and the proposal in this document addresses to the
problem of dual-connectivity of 3GPP access with Master-gNB having
poor coverage.
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 RFC 2119 [1].
3. User data flow for Dual Connectivity for 3GPP 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).
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+-------------------------------+
| |
| +------------------+ |
| | | |
| | |N8 |N15
| | | |
+------+ | | +------+ N13 +-----+ |
| NSSF |---+ | | | AUSF |-------| UDM | |
+------+ | | | +------+ +-----+ |
| | | | | |
| | | | | |
N22| | | |N12 |N10 +-----+ N5 +----+
| | | +---+ | | PCF |------| AF |
| | | | | +-----+ +----+
| | | | | |
| | | | | |
+-----+ +-------+ +-----+ |
UE---| RAN |-------| AMF |------------| SMF |-------+
+-----+ N2 +-------+ N11 +-----+ N7
| |
| |
| |N4
| |
| |
| N3 +-----+ N6 +-------------+
+-------------------------------| UPF |--------| Service N/W |
+-----+ +-------------+
Figure 1 : Simplified 5G-system Architecture for RAN access
For clarity in the current document proposal, multiple node/
function like UDSF, NRF, and interfaces N9, N14 are not shown.
3.2 QoS
QFI is defined as Qos Flow ID is an identity to QoS flow in the 5G
system. All data traffic within a PDU session are labelled or
identified by QFI, it implies same QFI labelled data flow will
receive same traffic forwarding treatment like scheduling, priority
etc.
Data flow is via N3 (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.
3.3 Dual Connectivity
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Dual connectivity (DC) concept developed for 3GPP access, functional
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.
3.4 Problem Statement
Problem statement 1: Inspite in a Dual connectivity of 5G system user
experience is impacted because of Master-gNB may have degrade radio
condition and another Master-gNB is not available for handover where
as Secondary-gNB is available with sufficient radio resource.
4. Proposal of Bearer Offloading Dual-Connectivity with 3GPP access
The solution proposed in this document to solve the degrade Rf
condition at Master-gNB while handover to another Master-gNB is
not possible and UE have better or improved Rf condition with
Secondary-gNB(as compared to Master-gNB).
Figure 2, show below shows how radio resource control can be handed
over from Master-gNB to Secondary-gNB.
- 5G user (UE) is being served by Master-gNB
- Master-gNB adds Secondary-gNB for delivering user data to UE
- UE is register to 5G-core via Master-gNB , whereas there is no
user context available between Secondary-gNB and AMF
- There is X2 interface between master-gNB and Secondary-gNB defined
in 3GPP specification.
- User data is deliver over N3 interface between UPF and Master-gNB
- Master-gNB splits the partial User data over x2 interface to
Secondary-gNB.
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+--+ +-----+ +-----+ +---+ +---+ +---+
|UE| |M-gNB| |S-gNB| |AMF| |SMF| |UPF|
+--+ +-----+ +-----+ +---+ +---+ +---+
| | | | | |
| | | | | |
|<==User Data==>|<==============User Data==============>|
| | | | | |
| Measurement | | | | |
|<--------------| | | | |
| Control | | | | |
| | | | | |
| Measurement | | | | |
|-------------->| | | | |
| Report | | | | |
| | | | | |
| ------------- | | | |
| | HO Decision | | | | |
| ------------- | | | |
| | | | | |
| | | | | |
| | S-gNB HO Request | | |
| |--------->| | | |
| | (carry SCG configinfo) | |
| | | | | |
| | | | | |
| | | | | |
| | S-gNB HO Req.Ack | | |
| |<---------| | | |
| | | | | |
| | | | | |
|<-----RRC procedure------>| | | |
| | | | | |
| | | | | |
| --------------------------------------------
| | PATH UPDATE PROCEDURE and FILTER |
| --------------------------------------------
| | |
|<========User Data=======>|<==========User Data=======>|
| | |
Figure 2: Bearer Offloading Dual-Connectivity with 3GPP access only
- Based on Measurement report, Master-gNB take decision to execute a
procedure of handover to Secondary-gNB with SCG configuration.
- Secondary-gNB establish connection with AMF to cater user's all
signalling and data traffic.
- Master-gNB also provides a radio (Rf) bearer splitting template
termed as 'FILTER'. This bearer template FILTER is delivered to
UPF via SMF.
- UPF now shift the user data on N3 interface from Master-gNB to
Secondary-gNB. This Secondary-gNB will act as new Master-gNB.
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Please note that this FILTER value in this scenario of handover from
Master-gNB to Secondary-gNB MUST empty or NULL, implies that user
traffic segregation is completely governed by AMF and SMF based on
PCC rules and policies.
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.
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9. References
9.1. Normative References
[1] 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
[TS23.501]
"3GPP TS23.501, System Architecture for the 5G System
(Release 15)", 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.
[TS23.502]
"3Procedures for the 5G System", March 2018.
[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
[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
Dharmendra Dwivedi
Ericsson Global Service, India
EGI, Mahadev Pura,
EMC Square, Outer Ring Road,
Bengaluru, India
Email: dharmendra.dwivedi78@gmail.com
Harsh Vardhan Singh Chauhan
Gwalior, MP
Email: vardhan.chauhan@gmail.com
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