Download Lecture Optical Communications Overview

Lecture
Optical Communications
Outlook
Prof. Dr.-Ing. Dipl.-Wirt.-Ing. Stephan Pachnicke
Overview
• Next generation access networks
• Functional and structural convergence of fixed and mobile
networks
• Conclusion
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11 - Trends
Traffic Growth in the Internet
DE-CIX GlobalPeer
• Exponential growth of the bandwidth with approx. 30% p.a.
• Drivers are new services such as IP-TV, Cloud, …
3
11 - Trends
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Access Network Technologies
Fiber-to-the-Home
10G-EPON, XG-PON
Fiber-to-the-Curb
ADSL
Copper
ISDN
Year
• DSL-based technology cannot be scaled to higher data rates
•
•
VDSL2 ~100 Mbit/s with reach of ~550-850 m
G.fast (Vectoring) ~150 Mbit/s, ~250 m reach
Fiber-to-the-Curb
• Solution: fiber based systems, passive optical networks (PON)
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System Architecture (FTTx)
Point-to-point
CO
GPON
TDMA-PON
Passive
splitter
CO
NG-PON2
WDM-PON
WDM
Mux/Demux
CO
Acronyms:
+
Physical layer p2p connection
+
High reach (approx. 80 km)
+
Aggregate bit rate/fiber = end user bit rate
–
N fibers in the CO
–
N transceivers in the CO
+
1 fiber in the CO
+
1 transceiver in the CO
–
Shared multipoint connection
–
Lower reach (approx. 10 km)
–
Aggregate bit rate/fiber = N x end user bit rate
+
Physical layer p2p connection
+
Medium reach (approx. 40 km)
+
1 fiber in the CO
+
1 transceiver in the CO
+
Aggregate bit rate/wavelength = end user bit rate
CO=Central office; TDMA=Time Division Multiple Access; WDM=Wavelength Division Multiplex
GPON=Gigabit capable passive optical networks; NG-PON2=Next Generation–PON2
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WDM-PON Challenges
Customer Premises
Central Office
Challenges
Solutions
• Integration of multi-channel
transmitters and receivers
• Photonic integrated circuit
(PIC) (& driver array)
• Low-cost tunable laser
• Development of a novel
(wavelength) tunable
tranceiver module with
centralized control
SFP+
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11 - Trends
2
Transmission System Setup
OLT
ONU
AWG
(G.698.3)
SFP
(L-Band)
1GBE
.
.
.
L-Band
(RX)
RN
L-Band
C-Band
(TX)
CPE
(with T-SFP+)
.
.
.
C-Band
VOA
Fiber
AWG
(G.698.3)
90%
SFP
(L-Band)
1GBE
C-Band
AWG
10%
L/C Splitter
Wavelength
Controller
CPE
(with T-SFP+)
OLT: optical line terminal; RN: remote node;
ONU: optical network unit; VOA: Variable Optical
Attenuator; AWG: arrayed waveguide grating
CPE: Customer Premises Equipment
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Field Trial WDM-PON (2014)
•
Two different fiber routes (looped back to central office)
•
15 km – red (approx. 7 dB attenuation) – Gmunden to Olsdorf
•
25 km – orange (approx. 11 dB attenuation) – Gmunden to Laakirchen
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Results
S. Pachnicke, et al, OFC,
Los Angeles, 2015.
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Automatic Wavelength Control
194,9
Frequency [THz]
194,8
194,7
194,6
194,5
194,4
0
10
20
30
Phase 1
(Power Feedback)
40
50
Time [s]
60
70
80
90
100
Phase 2
(Wavelength & Power Feedback)
On turn-on the ONU automatically tunes to the wavelength, which is
equivalent to the AWG port it is attached to (considering the wavelength and
power feedback it receives from the centralized controller)
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Long Term Stability
Long-term wavelength stability is achieved by the closed-loop wavelength
control provided by the central office
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Convergence of Fixed and Mobile
Networks
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4
Increase of Mobile Traffic
Quelle: Cisco VNI Mobile, 2015
• Global mobile traffic will reach 24.3 EB/month in 2019
• Bandwidth growth of approx. 57% p.a.
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Fixed-Mobile Convergence (FMC)
NID / RGW
Universal Access Gateway
UAG
Carrier Ethernet
Switch / Aggregator
U
E
eNB
NFV
Access- and
aggregation network
Server
WiFi AP
Low-Latency Cross-Connect
eNB ONU
Small
Cell
RRU ONU
RRU ONU
RRU ONU
WDM-PON OLT
Mobile
Fronthaul
Shared use of the infrastructure by fixed and mobile networks
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Advantages
Use of a shared infrastructure for fixed and mobile networks:
•
Improved QoE for the end user (e.g. seamless handover between WiFi/LTE)
•
Reduced costs and lower energy consumption
Differentiation into
•
•
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Functional convergence wrt. required functions in fixed and mobile networks
•
Enhanced control
(improved offloading, seamless handover between fixed and mobile networks)
•
Use of virtualized functions on a shared NFV server
(e.g. for universal authentication functionality, universal data path management, …)
Structural convergence wrt. the infrastructure
•
Shared use of network infrastructure
(e.g. PON network for FTTH & dedicated wavelengths for mobile fronthaul)
•
Consolidation of network nodes
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Functional Convergence
Management / Control
SDN UAG
/ OpenFlow
GbE / 10GbE Carrier Ethernet
Switch / Aggregator
eNB
NFV
Aggregation
Server
Network
WiFi AP
IP / MPLS
SDN / OpenFlow VNF 1
Access and
Backbone
LER
VNF 2
VNF 3
SDN / OpenFlow
BBUH
Low-Latency Cross-Connect
Sync
Timing
WDM-PON OLT
RRU ONU Mobile
RRU ONU
RRU ONU Fronthaul
Content
Cache
Mobile
EPC
uAAA
Perform. Interface
Monitor
Select
Enhanced control & virtualization functions
(SDN/OpenFlow Controller, NFV-Server)
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NFV & SDN
Network Function Virtualization
(NFV)
Software Defined Networking
(SDN)
Cache Firewall Router
App
App
App
API’s
Rework of network applications
to run on arbitrary hardware,
independent of custom networking hardware
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Forwarding plane is
programmable in real time
by independently developed
software
11 - Trends
Network Function Virtualization
(NFV)
Traditional Network Appliances
Message
Router
CDN
DPI
Firewall
Carrier
Grade NAT
Tester/QoE
Monitor
SGSN/GGSN
PE Router
BRAS
RAN Controller
Virtualized Network Functions
Session Border
WAN
Controller
Acceleration
Standard, high-volume
servers
Standard, high-volume
storage
Standard, high-volume
switches
Use of commodity hardware (e.g. blade server),
software-based network functions,
faster innovation cycle
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Examples of NFV
Implementations
Mobile Networks
• Virtual EPC (vEPC), Centralized RAN (C-RAN)
Residential Customers
• Virtual Home Gateway (vHG)
Business Customers
• Virtual Customer Premises Equipment (vCPE)
First use in mobile networks
then for residential and business customers
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Advantages of NFV
Physical
Network
Hybrid
Network
Virtual
Network
Scope
Functions tied to
hardware
Selective functions virtualized with gradual
introduction of orchestration
Orchestration across
virtualized functions
Operations
Slow, manual service
creation
Gradual transition, benefits expand as
scope of virtualization grows
Automated real-time
service creation
Cost
CAPEX-heavy,
over-provisioning
Initial impact may be limited, because
functions are virtualized in isolation
OPEX-heavy, licensebased model
Innovation
Cycle
Innovation tied to both
hardware and software
Impact depends on which functions are
virtualized
Software and hardware
become independent
Source:
It is crucial to find the right way to a fully
virtualized network
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Example: Double Attachment
SDN Controller
Network Assistance for
Access Selection and Utilization
Control Plane
UE
WiFi AP Changing
(Inter-AP Handover)
WiFi AP
WiFi AP
Double
Attachment
Interface Changing
(Inter-system Handover)
SDN-API
Northbound
uAAA
U
E
U
E
Interface
Selection
Access- and
aggregation network
UAG
LTE-EPC
Performance
Monitoring
U
E
Content
Cache
SDN: Software-defined networking, uAAA: universal
Authentication, Authorization and Accounting, UAG: universal
access gateway, EPC: evolved packet core; UE: user equipment
•
User Equipment (UE) authenticates via uAAA in mobile and WiFi networks
•
UE can be attached via different paths at the same time (double attachment)
•
Centralized network control steers traffic (offloading)
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Example: Centralized-RAN
Management / Control
SDN UAG
/ OpenFlow
GbE / 10GbE Carrier Ethernet
RRU ONU
RRU ONU
RRU ONU
Switch / Aggregator
NFV
Aggregation
WiFi AP
IP / MPLS
SDN / OpenFlow VNF 1
Access and
Server
Network
Backbone
LER
VNF 2
VNF 3
SDN / OpenFlow
BBUH
Low-Latency Cross-Connect
Sync
Timing
WDM-PON OLT
RRU ONU Mobile
RRU ONU
RRU ONU Fronthaul
Content
Cache
Mobile
EPC
uAAA
Perform. Interface
Monitor
Select
Use of BBU hoteling.
Advantages by
• Sharing of the same BBU for serving a business area in day time
• and a residential area during night
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11 - Trends
Conclusions
•
Bit rates in access networks will increase exponentially in the next years
•
Fiber-to-the-Home systems will be the only long-term solution
•
Especially WDM-PON systems are promising due to their high bandwidth
and low latency
•
Fixed- and mobile networks will converge in the future
•
NFV & SDN will allow flexible reconfiguration of the network and
realization of network functions in software
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