Bristol 5G city testbed with 5G-XHaul extensions

IMPACT OF 5G RAN ARCHITECTURE IN TRANSPORT

NETWORKS

Daniel Camps (i2CAT)

ONDM 2018 – Optical Technologies in the 5G era (Workshop)

OUTLINE

� From 4G to 5G architecture

� The F1 interface and new RRC states

� The F2 interface (3GPP and eCPRI)

� 5G deployment options

� 5GPICTURE’s view on a converged 5G transport

� Thoughts on transport support for 5G QoS

� Conclusions

2

FROM 4G TO 5G ARCHITECTURE

3

E-UTRAN (LTE)

eNB

(RRH-BBU)UE

X2S1-MME

S1-U

Serving

Gateway

PDN

Gateway

S5

S1

0 HSSS6

a

PCRF

Gx

PDNs

APNs

SGiU-Plane

C-Plane

EPC

MME

S11

S1-C

5GNR

gNB-CUUE

XnN2

N3

UPF UPFN9

N14AUSF

PCF

DNNs

APNs

N6U-Plane

C-Plane

5GCore

gNB-DU

F1

RRH

F2

SMF

N4AMF

N11

NSSF

N7

N1 (S-NSSAI)

N12N22

F1 INTERFACE AND NEW RRC STATES

4

� F1 functions:

� Mgmt CU-DU (discovery, reset, etc)

� SIB delivery from CU to DU

� UE context mgmt: F1 sessions

maintained per UE

Radio Network Layer

UDP

IP

Data link layer

Physical layer

Transport

Network

Layer

GTP-U

User Plane

SCTP

IP

Data link layer

F1AP

Physical layer

Radio Network Layer

Transport

Network

Layer

Control Plane

gNB-CU

gNB-DU

SDAPPDCP

RLCMACPHY

F1

Non-Real time

Real time

RRC

WT802.11

Non-3GPP

Xw

RLCMACPHY

Real time

F1

IP flow anchoring

F1 INTERFACE AND NEW RRC STATES

5

gNB-CU

gNB-DU gNB-DU gNB-DU

gNB-CUXn

F1 F1 F1

UE

AMF

N2 N2

intra-CU F1 handoverinter-CU F1 handover

RRC ConnectedN3: ESTABLISHED

F1: ESTABLISHED

RRC IdleN3: RELEASED

F1: RELEASED

RRC InnactiveN3: ESTABLISHED

F1: RELEASED

UE RRC STATES

Location kept by gNB-CU in terms of RNA

(RAN Notification Areas)

F2 INTERFACE (3GPP AND ECPRI)

� Not much progress inside 3GPP � Work in parallel carried out by eCPRI

� A variety of potential splits considered

6

I/Q Time Domain

I/Q Freq. Domain

5GPICTURE D4.1 - http://www.5g-picture-project.eu/

F2 REQUIREMENTS SUMMARY

� From eCPRI

� 3/1.5 Gbps user throughput

� 500 PRBs

� 8/4 DL/UL MIMO layers

7

� 64 Antennas

� Digital BF in eREC

� 256QAM

� IQ 30 bits/sample

F2 INTERFACE SCALABILITY [1]

8

10G Ethernet, ~CPRI rate 8

�can support only 4G, low load/split

C, no support of 5G split A/full

centralization

400G Ethernet (IEEE P802.3bs)

�supports all splits/RATs

�for 5G split A/full centralization only a few cells can be

aggregated in one link

4G4G

Split

E

Split

IID

Split

B

Split

E

Split

IID

Split

B

[1] Bartelt, Jens, et al. "5G transport network requirements for the next generation fronthaul interface." EURASIP Journal on Wireless

Communications and Networking 2017.1 (2017): 89.

5G DEPLOYMENT OPTIONS

9(*) 5G-RAN target OWD delays: 4 ms eMBB, 0.5 ms URLLC

[1] Andy Sutton, BT, 5G Network Architecture, available at: https://www.youtube.com/watch?v=aGEAQJ7U1tA

DU

CU

DU

CU

DU

DU

Small Cell - CU

DU

DU

RRH

Macro-CUUPF

App server

App serverApp server

UPF

UPF

MEC

MEC 5GCore

App

serverMEC

Internet

mmWave – 60GHz

Aggregation CoreAccess

mmWave

26/28GHz

(reqs. > 10 GBps)

100 MHz – 3.5 GHz

(reqs.~ 10Gbps (F1))

Macro-DU

UPF location [1] Access Aggregation Core

Num. Sites 1200 106 10

Transport latency 0.6 ms 1.2 ms 4.2 ms

Estimated 5G

latency (*)

9.2/2.2 ms

(eMBB/URLLC)

10.4/3.4 ms

(eMBB/URLLC)

16.4/9.4 ms

(eMBB/URLLC)

Access fibre, e.g.

WDM-PON

NFVI NFVI NFVI

5GXHAUL & 5GPICTURE’S VIEW ON A MULTI-TENANT 5G TRANSPORT

10

Data Plane

Control Plane

THOUGHTS ON TRANSPORT SUPPORT TO 5G QOS

� F1, N3, Xn, Xw interfaces are all based on GTP

� GTP TEID identifies per-UE sessions

� GTP extension header will carry the 5G QoS Flow ID (QFI)

� Can we directly map 5G QoS to transport flows (at least at the edge)?

� i.e. establish transport flows according to UE’s RRC transitions

� Analysis performed based on an operational LTE network in Greece (33

cells)

11

State maintained at each transport node Signalling load with transport controller

SUMMARY AND CONCLUSIONS

� 5G RAN base station decomposed into RRH – DU – CU

� “Backhaul-like” F1 interface below PDCP between CU

and DU

� Multiplicity of options (functional splits) between DU

and RRH

� 5G’s flexibility provides built-in support for low latency

applications within the network

12

Thanks for your

attention!

Questions?