Cai Jingzhe: The Combo PON solution will become the
optimal choice for operators
High-bandwidth services including 4K/8K television, 3D
gaming, live interaction, Virtual Reality (VR) and Augmented
Reality (AR) have been growing exponentially over the last few
years. Faced with fierce competition and driven by national
broadband policies, operators are accelerating broadband
network deployments. As higher bandwidth is needed, GPON, which
is currently a major broadband technology, is increasingly
unable to meet the bandwidth demand of the ever expanding
high-bandwidth services. To enhance user experience and create
new value points, operators need a new technology that delivers
higher bandwidth and better services.
When upgrading GPON to 10G GPON, operators have to consider
a number of factors, including the reuse of the existing
resources, fast deployment, and forward/backward compatibility
in order to save the overall cost of the network and meet
customers’ requirements at the same time.
Furthermore, in order to cater to the continuous development of
services, the network needs to be planned and
constructed/upgraded in advance.
At present, operators are quickening the pace to deliver 100
Mbps broadband to users and are devoting major effort to
providing video services, deploying 1000 Mbps-to-premise pilot
trials at an accelerated pace and expanding the application
range. Delivering 1000 Mbps to premises has become the next
target of broadband acceleration.
As a commercially mature technology, 10G GPON technology
perfectly meets operators’ needs by providing
higher bandwidth to enable service growth. Most operators have
begun to explore solutions for upgrading GPON to 10G GPON in at
a low-cost, flexible and fast fashion.
CHALLENGE ANALYSIS OF THE UPGRADE FROM GPON TO 10G
There are two methods in upgrading to 10G PON, one being from
EPON to 10G EPON and the other from GPON to 10G GPON.
Featuring outstanding compatibility and supporting flexible
access of EPON ONUs and 10G EPON ONUs under the same PON port,
the upgrade from 1G EPON to 10G EPON is convenient. The
operator only needs to add a 10G EPON line card on the OLT
side, and then add a 10G EPON line card on the ONU side
– the ODN doesn’t need to change.
External WDM1r is considered the traditional method of
upgrading GPON to 10G GPON. The advantage of this solution is
that only an external WDM1r needs to be added in the ODN
network. It’s also easy and fast to migrate from
GPON to 10G GPON. According to the related factors such as
network resources, when using the external WDM1r solution, a
new OLT shelf, 10G GPON line card, external WDM1r, jumper fibre
or even other attached resources such as an ODF may be
required. There is a risk that the existing network cannot be
upgraded. This might be for the following reasons:
- It requires adding an OLT or line card, upstream link,
and upper-layer interconnection device and port, which places
higher demands on the equipment rooms’
auxiliaries including space, power supply and more. However,
the existing equipment rooms may not be able to meet these
- The external WDM1r solution requires adding a multitude
of WDM1rs’ and adding OLT racks or an ODF, which
brings internal fibre storage problems. However, the existing
network deployment may not able to meet these
- The introduction of WDM1r adds an insertion loss of 1 to
2 dB, while the planned and actual ODN power budget allowance
may be insufficient. Imprudent and improper upgrades may
interrupt existing GPON services or even disable the upgrade;
therefore the existing power budget should be calculated
precisely before the upgrade
- The introduction of new passive devices requires
adjusting the fibre routing and distribution, which makes the
network management, operation and maintenance (O&M) much
COMBO PON ENABLES ON-DEMAND AND LOW-COST UPGRADE
FROM GPON to 10G GPON
Combo PON combines GPON and 10G GPON wavelengths within one
optical transceiver module, transmitting and receiving GPON and
10G GPON signals separately. It is compatible with existing
GPON services, supports high-bandwidth services, and reuses
existing network equipment and ODN resources without the need
for altering existing network resources or occupying additional
equipment room space. It supports replacing user-side ONUs as
per service package to implement rapid and smooth service
upgrade. The diagram below shows Combo PON implementing
simultaneous access of GPON and 10G GPON.
The Combo PON solution enables a smooth upgrade to
high-bandwidth services simply by replacing the line cards.
Compared with the external WDM1r solution, the Combo PON
solution has the following advantages:
The Combo PON solution does not require additional external
equipment and auxiliaries, dramatically reducing the equipment
footprint. For example, when upgrading a rack that is fully
loaded with two GPON OLTs to 10G GPON, the Combo PON solution
saves more than 60% of the equipment room space. In addition,
no additional equipment means fewer O&M problems.
Reduced equipment room space and simplified
Less initial investment and quick rate on
The cost of 10G GPON ONUs is much higher than that of GPON
ONUs. By leveraging the Combo PON solution, carriers can
upgrade the ONUs as needed. This enables an asset-light
upgrade to 10G GPON, avoids heavy investment in directly
deploying 10G GPON ONUs, and achieves ROL.
Smooth network evolution without affecting
the current GPON services
Massive rollout of GPON services may lead to a tight
optical power budget for some regions and users. The
external WDM1r solution introduces an additional insertion
loss of 1 to 2 dB, which may degrade the in-service GPON
ONUs ability to work properly and thus affect the existing
services. The Combo PON solution leverages a built-in WDM
to ensure that the GPON and 10G GPON optical power budget
is within the normal range, and in turn ensures that the
existing services are not affected.
The Combo PON solution reduces the amount of
Central-Office (CO) equipment and auxiliary equipment as well
as OLT and ODN resources. Compared with the external WDM1r
solution, it saves the construction cost by 26%. The below
diagram lists the comparisons between Combo PON and external
COMBO PON SUPPORTS BOTH UPGRADE AND NEW-BUILT
The Combo PON solution suits both GPON to 10G GPON upgrade
scenarios and newly-built scenarios. In the initial period of
network construction, carriers need to take the construction
costs and resources into full consideration, use Combo PON
cards on the OLT side, and deploy GPON ONUs to meet
low-bandwidth deployment requirements.
When the users’ bandwidth demand increases,
carriers can deploy 10G GPON ONUs directly or replace
existing GPON ONUs with 10G GPON ONUs and make no change to
the OLT side so that the initial investment is controllable
and the on-demand migration to 10G GPON is guaranteed.
ZTE is dedicated to providing differentiated, innovative
solutions and products that deliver more value to customers.
ZTE’s Combo PON solution supports inserting
Combo PON cards into the existing OLT chassis and supports
the access of both GPON and 10G GPON ONUs. Through tests and
verifications, ZTE’s Combo PON solution proves
to be satisfactory.
Later, ZTE will provide the Combo PON solution that
supports the migration to NG-PON2. With the soaring big video
services, the migration from GPON to 10G GPON is unavoidable.
It is estimated that the Combo PON solution will become an
optimal choice when migrating from GPON to 10G GPON.