Report on the Successful Demonstration of Innovative Basic Technologies
for Future Optical Access Network “Elastic Lambda Aggregation
Network”
Elastic
access-metro integrated network that flexibly changes the transmission speed
and optical frequency bandwidth towards future multiple services accommodation
beyond 2030
TOKYO, Apr 26, 2017 –
(JCN Newswire) – Nippon Telegraph and Telephone Corporation, Hitachi, Ltd., Oki
Electric Industry Co., Ltd., Keio University, KDDI Research, Inc. and Furukawa
Electric Co., Ltd. have jointly challenged the advanced future network for 2030
and beyond by conducting innovative studies on “Elastic Lambda Aggregation
Network”(1).
Elastic Lambda Aggregation Network sets an
adaptive modulation(2) OFDM(3) transmission system, which leads to the
significant improvement of optical frequency utilization efficiency, into the
access (subscriber’s home-central office)-metro (central office-central office)
network that directly connects the subscriber’s home and the metro central
offices via fibers and WSSs(4). Therefore, Elastic Lambda Aggregation Network
provides flexible assignment of the transmission speed and optical frequency
bandwidth to support diversified services with different types of traffic, such
as internet, enterprise line, and mobile services.
We demonstrated the reliability of Elastic
Lambda Aggregation Network through a prototype testbed network which utilizes
optical path provisioning and switching technologies. The demonstration
successfully showed, for the first time, that the service accommodated in the
failed office was automatically re-connected within 10 sec to another office
some 10km away with the same transmission speed as before the failure. The
project accomplishments will be presented at an international conference on
optical communications, iPOP2017 (The 13th International Conference on IP +
Optical Network 2017: Kawasaki-city, Kanagawa, Japan: June 1-2, 2017).
This research and development project was contracted
with the National Institute of Information and Communications Technology (NICT)
of Japan under a research contract titled “Research and development of
elastic lambda aggregation network.”
Background
Along with the wider penetration of FTTH (Fiber
to the Home) services, efficient operation of a large number of network sets is
essential in recent optical access networks. Moreover, the future access
network must support, in addition to conventional FTTH service, multiple access
services, such as mobile, high-definition video and IoT (Internet of Things)
services.
Until now, multiple access services have been
provided using distinctly different network infrastructures to meet the
disparate service requirements. However, to provide them more efficiently, all
services should coexist on the same service-adaptive network that can flexibly
meet individual service requirements. If multiple access services share an
optical fiber network, high reliability is essential so that the network can
keep providing services by autonomous reconfiguration of the network
resources(5) remaining after a disaster. Furthermore, high optical frequency
utilization efficiency (transmission rate per unit of optical frequency) should
also be provided to accommodate a large number of services and
subscribers.
From this background, as advanced research
studies targeting beyond 2030, the six institutions (NTT, Hitachi, OKI, Keio,
KDDI Research, and Furukawa Electric) have been researching Elastic Lambda
Aggregation Network, a service adaptive access-metro network that provides
multiple services with high reliability and high optical frequency utilization
efficiency.
Elastic lambda Aggregation Network
In conventional access networks, the central
office equipment (OLT) is located at access central offices close to
subscribers’ homes. Elastic Lambda Aggregation Network, on the other hand,
transfers the OLT to a metro central office that aggregates the traffic of
metro networks. Moreover, Elastic Lambda Aggregation Network improves the reliability
of access-metro networking, which will need to accommodate a huge number of
subscribers, by using WSSs to switch optical paths flexibly. This innovative
architecture offers lower end-to-end latency and power consumption, since
Optical-Electrical-Optical (O-E-O) conversion in the access central office is
not needed.
Elastic Lambda Aggregation Network employs a
digital coherent(6) OFDM system with adaptive modulation, a technique that can
realize dramatically high optical frequency utilization efficiency and
large-scale flexible service allocation by using the elastic control of
transmission speed and optical frequency bandwidth. In addition, Elastic Lambda
Aggregation Network applies the world’s first dynamic bandwidth allocation
algorithm in OLTs. This makes it possible for the users to share the additional
bits in a fair manner regardless of optical distribution network (ODN)
conditions.
Project Details and Accomplishments
The jointly developed Elastic Lambda Aggregation
Network consists of six basic technologies as follows.
1. Dynamic bandwidth allocation algorithm in OLT
[NTT]
Elastic Lambda Aggregation Network accommodates
multiple subscriber premise sets (ONUs) that have different ODN conditions,
thanks to adaptive modulation; it assigns high bit rate optical signal
parameters to near ONUs which yields additional bits. Our dynamic bandwidth
allocation algorithm shares these additional bits among all users in a fair
manner while also satisfying traffic requirements. Successful demonstrations
using an OLT and 512-ONUs have been conducted.
2. Telecommunication control technology for
adaptive modulation OFDM transmission system [Hitachi]
Hitachi developed a telecommunication control
protocol that features automated search of ONU responding to adaptive
modulation OFDM transmission system and automated set up various optical signal
parameters in ONU. When optical transmission line is disconnected by any
disasters, this developed technology is capable of recovering the transmission
automatically by optimizing optical signal parameters for newly-built optical
transmission line. Conventionally, this type of transmission recovery has been
difficult to perform. Hitachi developed a prototype of OLT and ONU applying
this technology on their logic circuits and realized the demonstration of
recovery operation.
3. Programmable OFDM transceiver and adaptive
control algorithm [OKI]
OKI developed a programmable digital coherent
OFDM transceiver that offers high-speed digital signal processing. It can
change the optical signal parameters dynamically. OKI has also developed an
adaptive control algorithm that decides the most suitable optical parameters
for the current network configuration. These technologies maximize Elastic
Lambda Aggregation Network performance in the context of high optical spectrum
efficiency.
4. Dynamic traffic capacity allocation algorithm
among multiple OLTs [Keio University: Prof. Naoaki Yamanaka, Faculty of Science
and Technology]
A Logical OLT (L-OLT) is defined as a subscriber
accommodation function configured in each OLT to provide the subscriber’s
required network service. Keio Univ. has developed an algorithm that calculates
the optimal placement (i.e. migration destinations) of L-OLTs and assigns
traffic capacity among multiple OLTs in about one millisecond based on policies
such as fault recovery or energy saving. The developed algorithm has been
implemented into the resource controller, which monitors and manages OLTs. Keio
Univ. has established dynamic subscriber accommodation technology that ensures
cooperation between the optical switch controller and OLTs.
5. Elastic optical path provisioning system
[KDDI Research]
KDDI Research, Inc., developed an elastic
optical path provisioning system (Optical Switch Controller) that can provide
optimum routes and available frequency grids considering multiple service requirements
(bitrate, quality of transmission, and latency etc.) in Elastic Lambda
Aggregation Network. In the case of network equipment or optical link failure,
this system calculates restoration paths and sets up WSSs.
6. High Port Count Wavelength Selective Switch
(WSS) [Furukawa Electric]
Flexible-grid WSS modules with 30 output ports
or more have been developed. Furthermore, a massive port count wavelength
selective switch with 93 output ports has been demonstrated experimentally. It
employs an input/output array with planar lightwave circuit technology. The
leading-edge technologies enable low insertion loss and massive port count
switches.
To validate the reliability of Elastic Lambda
Aggregation Network with the above six basic technologies, we conducted
protection experiments assuming a metro central office failure with total span
length of up to 40 km, 10 Gbps/channel and 512 ONUs accommodated in an OLT. The
demonstration successfully showed, for the first time, that the service
accommodated in the failed office was automatically switched to another office
some 10km away in real time with the same transmission rate as before the
failure; the switching time was short, less than 10 sec.
Future Outlook
We will work to enhance the maturity and the
reliability of basic technologies for Elastic Lambda Aggregation Network, and
will carry out further development activities.
(1) Elastic lambda Aggregation Network.
(2) Adaptive modulation
Adaptive modulation is the technology that
allows the system to adaptively change the optical signal parameters (the
modulation level, the symbol rate, the number of subcarriers and the carrier
frequency) according to the latest conditions of the optical distribution
network (ODN).
(3) OFDM
Abbreviation for Orthogonal Frequency Division
Multiplexing.
A number of subcarriers are multiplexed while
meeting orthogonality constraints, so even if they are transmitted with an
overlap in the frequency domain at a transmitter, they can be separated at a
receiver. This dramatically improves the frequency utilization efficiency.
(4) Wavelength Selective Switch
Wavelength selective switches select output
ports for individual WDM (Wavelength Division Multiplexing) channels without
Optical-Electrical-Optical conversion.
(5) Network resource
Network equipment, optical transmission network,
optical frequency resources etc.
(6) Digital coherent
Technique that remarkably improves optical
transmission performance by employing high-speed digital signal processing in
the optical transceivers
(JCN Newswire) – Nippon Telegraph and Telephone Corporation, Hitachi, Ltd., Oki
Electric Industry Co., Ltd., Keio University, KDDI Research, Inc. and Furukawa
Electric Co., Ltd. have jointly challenged the advanced future network for 2030
and beyond by conducting innovative studies on “Elastic Lambda Aggregation
Network”(1).
Elastic Lambda Aggregation Network sets an
adaptive modulation(2) OFDM(3) transmission system, which leads to the
significant improvement of optical frequency utilization efficiency, into the
access (subscriber’s home-central office)-metro (central office-central office)
network that directly connects the subscriber’s home and the metro central
offices via fibers and WSSs(4). Therefore, Elastic Lambda Aggregation Network
provides flexible assignment of the transmission speed and optical frequency
bandwidth to support diversified services with different types of traffic, such
as internet, enterprise line, and mobile services.
We demonstrated the reliability of Elastic
Lambda Aggregation Network through a prototype testbed network which utilizes
optical path provisioning and switching technologies. The demonstration
successfully showed, for the first time, that the service accommodated in the
failed office was automatically re-connected within 10 sec to another office
some 10km away with the same transmission speed as before the failure. The
project accomplishments will be presented at an international conference on
optical communications, iPOP2017 (The 13th International Conference on IP +
Optical Network 2017: Kawasaki-city, Kanagawa, Japan: June 1-2, 2017).
This research and development project was contracted
with the National Institute of Information and Communications Technology (NICT)
of Japan under a research contract titled “Research and development of
elastic lambda aggregation network.”
Background
Along with the wider penetration of FTTH (Fiber
to the Home) services, efficient operation of a large number of network sets is
essential in recent optical access networks. Moreover, the future access
network must support, in addition to conventional FTTH service, multiple access
services, such as mobile, high-definition video and IoT (Internet of Things)
services.
Until now, multiple access services have been
provided using distinctly different network infrastructures to meet the
disparate service requirements. However, to provide them more efficiently, all
services should coexist on the same service-adaptive network that can flexibly
meet individual service requirements. If multiple access services share an
optical fiber network, high reliability is essential so that the network can
keep providing services by autonomous reconfiguration of the network
resources(5) remaining after a disaster. Furthermore, high optical frequency
utilization efficiency (transmission rate per unit of optical frequency) should
also be provided to accommodate a large number of services and
subscribers.
From this background, as advanced research
studies targeting beyond 2030, the six institutions (NTT, Hitachi, OKI, Keio,
KDDI Research, and Furukawa Electric) have been researching Elastic Lambda
Aggregation Network, a service adaptive access-metro network that provides
multiple services with high reliability and high optical frequency utilization
efficiency.
Elastic lambda Aggregation Network
In conventional access networks, the central
office equipment (OLT) is located at access central offices close to
subscribers’ homes. Elastic Lambda Aggregation Network, on the other hand,
transfers the OLT to a metro central office that aggregates the traffic of
metro networks. Moreover, Elastic Lambda Aggregation Network improves the reliability
of access-metro networking, which will need to accommodate a huge number of
subscribers, by using WSSs to switch optical paths flexibly. This innovative
architecture offers lower end-to-end latency and power consumption, since
Optical-Electrical-Optical (O-E-O) conversion in the access central office is
not needed.
Elastic Lambda Aggregation Network employs a
digital coherent(6) OFDM system with adaptive modulation, a technique that can
realize dramatically high optical frequency utilization efficiency and
large-scale flexible service allocation by using the elastic control of
transmission speed and optical frequency bandwidth. In addition, Elastic Lambda
Aggregation Network applies the world’s first dynamic bandwidth allocation
algorithm in OLTs. This makes it possible for the users to share the additional
bits in a fair manner regardless of optical distribution network (ODN)
conditions.
Project Details and Accomplishments
The jointly developed Elastic Lambda Aggregation
Network consists of six basic technologies as follows.
1. Dynamic bandwidth allocation algorithm in OLT
[NTT]
Elastic Lambda Aggregation Network accommodates
multiple subscriber premise sets (ONUs) that have different ODN conditions,
thanks to adaptive modulation; it assigns high bit rate optical signal
parameters to near ONUs which yields additional bits. Our dynamic bandwidth
allocation algorithm shares these additional bits among all users in a fair
manner while also satisfying traffic requirements. Successful demonstrations
using an OLT and 512-ONUs have been conducted.
2. Telecommunication control technology for
adaptive modulation OFDM transmission system [Hitachi]
Hitachi developed a telecommunication control
protocol that features automated search of ONU responding to adaptive
modulation OFDM transmission system and automated set up various optical signal
parameters in ONU. When optical transmission line is disconnected by any
disasters, this developed technology is capable of recovering the transmission
automatically by optimizing optical signal parameters for newly-built optical
transmission line. Conventionally, this type of transmission recovery has been
difficult to perform. Hitachi developed a prototype of OLT and ONU applying
this technology on their logic circuits and realized the demonstration of
recovery operation.
3. Programmable OFDM transceiver and adaptive
control algorithm [OKI]
OKI developed a programmable digital coherent
OFDM transceiver that offers high-speed digital signal processing. It can
change the optical signal parameters dynamically. OKI has also developed an
adaptive control algorithm that decides the most suitable optical parameters
for the current network configuration. These technologies maximize Elastic
Lambda Aggregation Network performance in the context of high optical spectrum
efficiency.
4. Dynamic traffic capacity allocation algorithm
among multiple OLTs [Keio University: Prof. Naoaki Yamanaka, Faculty of Science
and Technology]
A Logical OLT (L-OLT) is defined as a subscriber
accommodation function configured in each OLT to provide the subscriber’s
required network service. Keio Univ. has developed an algorithm that calculates
the optimal placement (i.e. migration destinations) of L-OLTs and assigns
traffic capacity among multiple OLTs in about one millisecond based on policies
such as fault recovery or energy saving. The developed algorithm has been
implemented into the resource controller, which monitors and manages OLTs. Keio
Univ. has established dynamic subscriber accommodation technology that ensures
cooperation between the optical switch controller and OLTs.
5. Elastic optical path provisioning system
[KDDI Research]
KDDI Research, Inc., developed an elastic
optical path provisioning system (Optical Switch Controller) that can provide
optimum routes and available frequency grids considering multiple service requirements
(bitrate, quality of transmission, and latency etc.) in Elastic Lambda
Aggregation Network. In the case of network equipment or optical link failure,
this system calculates restoration paths and sets up WSSs.
6. High Port Count Wavelength Selective Switch
(WSS) [Furukawa Electric]
Flexible-grid WSS modules with 30 output ports
or more have been developed. Furthermore, a massive port count wavelength
selective switch with 93 output ports has been demonstrated experimentally. It
employs an input/output array with planar lightwave circuit technology. The
leading-edge technologies enable low insertion loss and massive port count
switches.
To validate the reliability of Elastic Lambda
Aggregation Network with the above six basic technologies, we conducted
protection experiments assuming a metro central office failure with total span
length of up to 40 km, 10 Gbps/channel and 512 ONUs accommodated in an OLT. The
demonstration successfully showed, for the first time, that the service
accommodated in the failed office was automatically switched to another office
some 10km away in real time with the same transmission rate as before the
failure; the switching time was short, less than 10 sec.
Future Outlook
We will work to enhance the maturity and the
reliability of basic technologies for Elastic Lambda Aggregation Network, and
will carry out further development activities.
(1) Elastic lambda Aggregation Network.
(2) Adaptive modulation
Adaptive modulation is the technology that
allows the system to adaptively change the optical signal parameters (the
modulation level, the symbol rate, the number of subcarriers and the carrier
frequency) according to the latest conditions of the optical distribution
network (ODN).
(3) OFDM
Abbreviation for Orthogonal Frequency Division
Multiplexing.
A number of subcarriers are multiplexed while
meeting orthogonality constraints, so even if they are transmitted with an
overlap in the frequency domain at a transmitter, they can be separated at a
receiver. This dramatically improves the frequency utilization efficiency.
(4) Wavelength Selective Switch
Wavelength selective switches select output
ports for individual WDM (Wavelength Division Multiplexing) channels without
Optical-Electrical-Optical conversion.
(5) Network resource
Network equipment, optical transmission network,
optical frequency resources etc.
(6) Digital coherent
Technique that remarkably improves optical
transmission performance by employing high-speed digital signal processing in
the optical transceivers
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