U2Net: Boosting ultra-broadband
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By Zhang Kejing
U2Net represents the way towards ubiquitous ultra-broadband network infrastructure,
as well as IP video and cloud services.
Recent developments in cloud applications and OTT services have had a big impact
on the telecom industry; Internet services are booming. As of 2011, fixed broadband
users in North America downloaded an average of 23GB data annually, at a
compound annual growth rate of over 20%. In Europe, average downloads totaled
40GB, with a growth rate of over 25%. Internet giants such as Google, Facebook,
YouTube, Amazon, and Netflix are changing our lives, with more to come in the form
of cloud computing.
Cloud technology represents an even greater leap forward, with operator networks
functioning as the pipes that introduce it to the end user, but ultra-broadband pipes
that deliver 100Mbps fixed access and 10-20Mbps mobile access will be needed to
truly enhance our lives and careers.
Lowering access network costs
Last-mile access performance is difficult to enhance. When networks are closer to
users, site installation and line layout become more complex. Legacy copper and coax
cannot be easily replaced by fiber; both of these aging media, together with existing
ducts and sites, are valuable assets that can be utilized to provide ultra-broadband
access on par with fiber.
Huawei's U2Net technology employs vectoring to enhance bandwidth over copper,
while transceiver technology eliminates crosstalk between twisted pairs, and VDSL2
delivers 100Mbps access at a distance of 100 meters. U2Net can be applied to a single
twisted pair for home access or bound twisted pairs for private enterprise lines or base
stations, which greatly lowers the cost of last-mile access.
HFC+DPoE/EoC is viable for coaxial cable. Based on DOCSIS 3.0 standards, its
channel bonding allows for four 6MHz (8MHz for EuroDOCSIS) channels that
provide downstream access rates greater than 100Mbps. However, for new buildings
and areas, fiber deployment is more cost-effective in the long run.
GPON technology, which is mature and stable, supports evolution to next-generation
10G GPON. Operators can overlap GPON with 10G GPON, which enables 10Gbps
downlink and 2.5Gbps uplink access. To minimize the number of sites, U2Net
provides the SingleFAN platform, which supports various access modes that use
high-capacity backplanes and a variety of boards. SingleFAN also supports smooth
evolution. Its optical line terminal (OLT) supports smooth evolution from PON to
10G PON and then 40G PON. By simply adding new service boards to MXUs,
operators can ensure smooth evolution from VDSL2 to vectoring and to G.fast,
without changing the ODN network.
However, seamless mobile access cannot occur without fixed network ubiquity. The
backhaul network required by a heterogeneous network (HetNet) should
accommodate any & all access nodes, including fiber, copper, and microwave. A
micro backhaul node would need to deliver access greater than 1Gbps to meet the
growing demands for LTE and LTE-A. Numerous multi-Gbps backhaul technologies
have emerged, including fiber-based IP backhaul, GPON, SuperMIMO, G.fast, header
compression for IP microwave, and E-band. A backhaul network should also
accommodate clock synchronization technologies such as Ethernet, 1588v2, and
1588ACR.
U2Net can provide 100Mbps access through any media, without legacy access
resource or network topology modification, thus lowering the costs of network
upgrade.
WDM intro to metro networking
Access network bandwidth expansion will require capacity expansion to the metro
network, which OTT traffic is already pressuring. As service traffic models change,
IPTV and OTT services that require long connections and wide bandwidth are
occupying a larger amount of metro resources; convergence ratios will decrease from
10:1 to 2:1.
OTT traffic transmission is migrating from point-to-point towards HTTP, with
HTTP-based adaptive streaming soon occupying metro bandwidth in a "best effort."
As a result, metro networks that provide port and traffic convergence will further be
flattened, and a larger number of links, directly connecting access networks to
broadband network gateways (BNGs), will be required; metro networks will therefore
need more fiber and bandwidth.
Metro network fiber addition involves complex engineering and is poorly scalable,
while WDM system introduction is complex (it involves OSNR calculation,
dispersion module configuration, wavelength planning) and warrants a large number
of service boards and multiplexing/demultiplexing boards.
However, OTN and PID technologies are maturing, which simplifies WDM
deployment in the metro network and dramatically reduces costs. PID integrates
receiving/transmitting with multiplexing/demultiplexing functions; one PID line
board can provide the functions that are traditionally provided by several boards,
including dispersion modules, service line boards, multiplexing/demultiplexing
boards, short-distance amplifiers, and monitoring boards.
Like SDH, PID is composed of tributary boards, cross-connection boards, and line
boards. Operators can select PID boards best suited for the transmission distances
involved, without any OSNR calculation, dispersion compensation, or wavelength
planning. Similarly to SDH, a PID board port can lead services to different sinks,
while engineers can also enhance O&M efficiency thanks to these similarities.
Through its adoption of OTN and PID technologies, U2Net can greatly reduce the
costs of introducing WDM to metro networks.
WDM introduction to metro networking is gaining momentum, and Huawei has
helped deploy over 300 metro-OTN networks in over 200 cities around the world.
Enhancing QoS
Traditional QoS for IP video services is provided in a best-effort manner. For video
sources deployed near BNGs, QoS can be ensured between the BNG and end user.
Either CDN or cache deployment to metro networks can enable cost-effective HD
OTT video provision; besides storing popular video content on the CDN & cache, the
solution can also enable precise user analysis based on video clicks. U2Net also adds
cache to the metro network, reducing costs & enhancing user experience.
Service providers will need to deploy universal service gateways on the BNG side to
manage users in a unified manner, while operators are considering IPv6 transition as
their IPv4 address resources deplete.
With its basis in the SingleMetro platform, U2Net provides a universal service
gateway that supports a smooth IPv6 transition through combined SR, BRAS, and
CGN. By integrating CGN boards with BRAS, U2Net simplifies NAT deployment.
Operators can smoothly evolve their CGN networks to DS-Lite networks, and then to
IPv6.
The upper BNG layer contains the backbone network, which bears three major types
of traffic: traffic-to-IGW, OTT-traffic-to-CDN, and cloud traffic-to-server. When
CDNs are deployed, most OTT traffic terminates in the metro network, relieving
pressure on the backbone. Traffic to IGWs has a predictable volume and is thus not
burdensome. Traffic flowing between end users and cloud servers, and traffic between
cloud servers, requires reduced delay and jitter, which is problematic for the
backbone.
As backbone networks flatten, access networks need to provide enhanced access
capacity, while network centers must provide highly-efficient forwarding capacity.
U2Net supports the networking of routers with 100GE ports and 48/80 wavelength x
100Gbps OTNs to achieve 100GE transmission over a long distance.
With cloud services booming, operators are in a strategic position between the cloud
and the terminal. U2Net enables 100Mbps access, guaranteeing a cloud-based,
ultra-broadband pipe.
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