5g: an ip engineer perspective - lacnic · same backhaul protocol stack as 4g 5g architecture and...
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5G: an IP Engineer Perspective
Igor GiangrossiSr. Director, Consulting Engineer | IP/Optical Networks
LACNOG 2019
2 LACNOG 2019
ITU-R IMT-2020 performance goalsWhat Is 5G?
Peak Data Rate (Gbps)
User Experienced Data Rate (Mbps)
Spectrum Efficiency
Mobility (Km/h)
Latency (ms)
Connection Density (devices/km2)
Energy Efficiency
Area Traffic Capacity (Mbps/m2)
20
100
3x
500
1
106
4G5G
100x
10
1
0.1
10x 1x
105
10
350
1x
10
1
Peak Data Rate
User Experienced Data Rate
Spectrum Efficiency
Mobility
Latency
Connection Density
Energy Efficiency
Area Traffic Capacity
High
Importance
Medium
Low
Massive MachineType Communications
Enhanced MobileBroadband
Ultra Reliable And Low Latency Communications
Source: ITU-R M.2038.0
3 LACNOG 2019
Same backhaul protocol stack as 4G5G Architecture and Traffic Flows
UPF
gNB AMF
InternetgNB
IP Core
Backhaul
IP
UDP
GTP-U
IP
IP
SCTP
NG-AP
User Plane (N3)
Control Plane (N2)
Xn
IP
GPS/1588v2
N6
SBA Bus
NAMF NSMF
N4
IP
TCP
HTTP/2
REST/JSON
IP
UDP
PFCP
SMF
AMF: Access and Mobility Management FunctionSMF: Session Management FunctionUPF: User Plane FunctionSBA: Service Based ArchitecturegNB: gNodeB (Radio)
4 LACNOG 2019
Requires a service-aware backhaul network5G Network Slicing for “Network as a Service”
gNB
AMF
N3
N2
SBA Bus
NAMF
NSSF
NNSSF
TE-enabledBackhaul
NSSF: Network Slice Selection Function
5 LACNOG 2019
4G CRAN architecture introduces CPRI for the Fronthaul networkRAN Densification: Searching for Better Radio Coordination
EPC: Evolved Packet CoreRRH: Remote Radio HeadBBU: Baseband Unit
Centralized RAN
S/PGW
RRH RRH RRH
BBU Pool
Backhaul
Fronthaul
eNBs
Time Division Multiplexing
IQData Ve
ndor
Spec
ific
Ethe
rnet
HD
LC
L1 In
-ban
dPr
otoc
ol
User PlaneControl &
ManagementSync
CPRI: Common Public Radio Interface
Requires DedicatedFiber (xWDM)
Ultra low delay variation (16ns)
P2P constant bitrate stream
6 LACNOG 2019
Targeting a 10X increase in throughput5G New Radio Main Technology Innovations
1GHz 6GHz 24GHz
mmWave
New Spectrum Options
Larger Radio Channels
Up to 400MHz
Massive MIMO
7 LACNOG 2019
CPRI bandwidth explosion with massive MIMOCurrent 4G CRAN Architecture Unfit for 5G Deployments
1Gbps
10Gbps
100Gbps
1000Gbps
1Tx20MHz
4Tx20MHz
64Tx20MHz
64Tx100MHz
14
64
320
*Approximate values
8 LACNOG 2019
Transport related standards bodies5G Standards Development Initiatives
Additional initiatives exist to address other areas of 5G standards (O-RAN, Small Cell Forum, etc.)
Main 5G standards (release 15):- Overall architecture- Radio- Core
Ethernet forwarding standards:- 802.1CM – Time Sensitive
Networks- NGFI – Next Generation
Fronthaul Interface• 1914.1 – Packet Based
Fronthaul• 1914.3 – Radio over
Ethernet
Fronthaul protocols:- CPRI v7.0 (2015)- eCPRI v1.2 (2018)
Fronthaul transport services specification:- MEF 22.3- MEF 22.3.1
9 LACNOG 2019
High bandwidth and strict latency4G RAN Protocol Split
PDCP
Option 7
RLC
MAC
PHY
RF
RRCIP
Option 6
Option 5
Option 4
Option 3
Option 2
Option 1
Layer 1
Layer 2
Max.Latency
RequiredBandwidth
CPRIOption 8
10 LACNOG 2019
Dual split options to enable Cloud RAN5G RAN Protocol Split
PDCP
Option 7
RLC
MAC
PHY
RF
RRCIP
Option 6
Option 5
Option 4
Option 3
Option 2
Option 1
Layer 1
Layer 2
Max.Latency
RequiredBandwidth
HighLayer
LowLayer
Option 8
11 LACNOG 2019
Cloud RAN with packet-based transport5G NR Introduces a New RAN Architecture
EPC/5GC
RU RU RU
DU
Backhaul
Fronthaul
CU
Midhaul
gNB
F1
Xn
NG/S1 NG/S1
CU: Centralized UnitDU: Distributed UnitRU: Radio Unit
DU DU
F1F1
RU RU RU
DU
CU
gNB
F1
DU DU
F1F1
Low Layer Split(Option 7-2a)
High Layer Split(Option 2)
12 LACNOG 2019
Similar to current backhaul protocol stackNew Midhaul Interfaces: E1 and F1
E1
F1-U F1-C
N3 N2
gNB
IP
UDP
GTP-U
User Plane
IP
SCTP
F1-AP
IP
SCTP
E1-AP
RU
DU
CU-UP CU-CP
13 LACNOG 2019
Designed for packet-based networkseCPRI: Fronthaul Transport over Ethernet
UserData
Real-TimeControl
OthereCPRI
ServicesSynchronization
ConnectionOAMC&M
eCPRI Protocol Header
eCPRI Services
UDP (Optional)
SyncEPTP SSH,SNMP, etc
ICMP
UDP, TCP,etc.
IPIP (Optional)
Ethernet (Etype:AEFE) VLAN+PCP MACSec EthernetOAM
14 LACNOG 2019
Savings of 10x compared to CPRIeCPRI Fronthaul Bandwidth Estimations
236Gbps
236Gbps
Down Up
Option 7-2(Uplink)
User/Up
Control/Up
20Gbps
<10Gbps
User/Down
Control/Down
Basic Assumptions: 100MHz8x4 MIMO (w/ 2 streams per uplink layer)64 AntennasTTI: 1msModulation: 256QAM*3Gbps downlink from MAC layer*1.5Gbps uplink to MAC layer
CPRIOption 7-2(Downlink)
eCPRI
20Gbps
<10Gbps
Drives 25GE interfaces
15 LACNOG 2019
Direct implication on inter-node distancesIEEE1914.1 & eCPRI Recommended One-Way Latency
Fiber Latency=5𝜇s/km
RU
Backhaul Fronthaul
DU5G Core
Midhaul
CU
UPF
>10ms
(50𝜇s for URLLC)
1ms 100𝜇s
>2000km
(10km for URLLC)
200km 20km
16 LACNOG 2019
QoS for mixing Fronthaul with other traffic flowsIEEE 802.1CM – Time Sensitive Networks
4
3
1
Fronthaul 2
Other
4 3 12Egress port:
Profile A: Strict PriorityFronthaul: High PriorityOther: Low Priority
134 2Egress port: 1
FramePreemption
Profile B: Frame Preemption (<10GE only)Fronthaul: Express TrafficOther: Preemptable Traffic
Supported Today
Requires MAC Change(mated boxes on a link)
Ingress traffic
17
Timing architecture driven by RAN features and TE budgeteCPRI Depends on External Synchronization
LACNOG 2019
RUDU
T-GM T-TSC
GPS
Tight TE Budget Relaxed TE Budget
RU
DU
Core
T-BC T-TSC
T-GM CU
T-BC
T-TSC
Fronthaul Backhaul Midhaul Fronthaul
G.8275.1 + SyncEG.8275.1 + SyncE
Category Max TE (ns)* RAN features
A+ ±20 (relative) MIMO, Tx-diversity
A ±70 (relative) Intra-band CA
B ±200 (relative) Inter-band CA
C ±1100 (absolute) Basic TDD, LTE CoMP/eICIC
*Note: Time error figures are between any two given RUs in the network, except for Category C which is an absolute value from the timing source (T-GM).
Class Constant TE (ns)
A ±50
B ±20
C ±10
Router TE classes(G.8273.2) Inter-RU Timing Requirements
RU
T-TSCTE
(relative)
RU
T-TSCTE
(relative)
18 LACNOG 2019
Radio and IP/Transport planning must be done togetherSummary: No One-Size Fits-All Solution
5G Core RU
Backhaul(>10ms)
Fronthaul(100us)
Midhaul(1ms)
DUCU
5G Core DU+RUCU
5G Core RUCU+DU
5G Core CU+DU+RU
Backhaul(>10ms)
Backhaul(>10ms)
Midhaul(1ms)
Fronthaul(100us)
Backhaul(>10ms)
DAT
A CE
NTE
R/N
FVI
