A Comparison between GPON and EPON
The access layer network is a fundamental platform for the delivery
and termination of various services. As subscribers to broadband
access services continue to grow rapidly, there is an ever-increasing
demand for broadband access bandwidth. As an ideal medium, optical
fiber provides high-speed and high-bandwidth multi-service
transmission. Fiber access, which offers many advantages in
delivering next generation services, has become one of the key
technologies of Next Generation Network (NGN).
Fiber to the home (FTTH) is the ultimate target in the access networks.
It is based on two passive optical network (PON) technologies:
Ethernet PON (EPON) and gigabit PON (GPON). Fiber-based
approaches promise an attractive way to deliver high bandwidth. In
fact, FTTH solutions based on EPON/GPON technology are becoming
more and more popular all over the world, improving end users'
experience by delivering high-speed triple play services.
Many carriers are already deploying PON FTTx network architectures
to eliminate the last mile bottleneck when providing high bandwidth
services to end users.
Asia is the major action point for EPON, accounting for 80% of
worldwide PON subscribers. In Japan, there are more than 7 million
FTTx subscribers at the end of 2006, and is projected to grow to more
than 17 million by the end of 2010. By the end of 2006, EPON
deployments represent about 80 percent of the worldwide FTTH
market. The remaining 20 percent of the FTTH market is based on
GPON, BPON, which are opted by North American carriers such as
Verizon and SBC, and point to point (P2P), which is favored by France.
EPON has massive deployment while GPON, as the next leading
technology, is still in its early stage of development. As fiber access is
poised for strong growth, carriers can choose between the two main
PON standards: EPON and GPON.
EPON vs. GPON
Both are accepted as international standards. They cover the same
network topology methods and FTTx applications such as
FTTH/FTTB/FTTO/FTTB; incorporate the same WDM technology,
delivering the same wavelength both upstream and downstream
together with a third party wavelength; and provide triple-play,
Internet Protocol TV (IPTV) and cable TV (CATV) video services.
There are also many differences between EPON and GPON. EPON,
based on Ethernet technology, is compliant with the IEEE 802.3ah
Ethernet in the First Mile standard that is now merged into the IEEE
Standard 802.3-2005. It is a solution for the "first mile" optical access
network. GPON, on the other hand, is an important approach to
enable full service access network. Its requirements were set force by
the Full Service Access Network (FASN) group, which was later
adopted by ITU-T as the G.984.x standards–an addition to ITU-T
recommendation, G.983, which details broadband PON (BPON).
xPON, as a FTTH technology, is an ideal solution to deliver last-mile
broadband access. The optical line terminal (OLT), optical network
unit (ONU) and optical distribution network (ODN), which comprise a
PON system, decide the costs of GPON and EPON deployments.
An ODN consists of fiber cable, cabinet, optical splitter, connector,
and etc. For the same number of users, the cost for the fiber and
cabinet with EPON is similar to that with GPON.
The cost of OLT and ONT is decided by the ASIC and optic module. The
GPON chipsets available in the market are mostly based on FPGA,
which is more expensive than the EPON MAC layer ASIC. There are
only several chipset vendors who can provide GPON chipsets, and it is
not likely that the price of GPON equipment can decline rapidly. The
optical module of GPON is also more expensive than EPON. When
GPON reaches deployment stage, the estimated cost of a GPON OLT is
1.5 to 2 times higher than an EPON OLT, and the estimated cost of a
GPON ONT will be 1.2 to 1.5 times higher than an EPON ONT.
ZTE's View on GPON and EPON
EPON is the dominant FTTH solution in Japan, Korea, China and other
Asia-Pacific countries, meeting the demand for services such as
high-speed Internet access, VoD, IPTV, and etc. In other countries,
especially in America, GPON is the preferred choice, as BPON and ATM
infrastructure is more prevalent in this area, and GPON can coexist
with the legacy PON systems. That explains why EPON appears to
gain an upper hand in the Asian market where BPON is not widely
As such, ZTE thinks that EPON and GPON will take their own shares in
the growing market in the next few years, and it is hard to say which
technology will replace the other in the near future.
ZTE, with its deep insight into network evolution, has launched both
EPON and GPON systems. The ZTE EPON and GPON systems support
high quality multicast and dynamic bandwidth allocation (DBA), and
provide VoIP, IPTV, CATV SDTV, L2 VPN and TDM leased line services.
EPON and GPON may be applied in different situations, and each
offers its own advantages in subscriber access networks. EPON
focuses on FTTH applications while GPON focuses on full service
support, including both new services and existing traditional services
such as ATM and TDM.
The ZTE xPON solution provides a uniform platform for both EPON and
GPON standards, supporting EPON and GPON mixed inserts in one
frame and enabling flexible networking applications.
The ZTE EPON/GPON system includes the ZXA10 C200/C220 OLT and
D/F series terminals. The ZXA10 C200 features small-to-medium
capacity, compact structure, high-density, high bandwidth and
scalability; the ZXA10 C220 delivers medium-to-large capacity. With
various kinds of ONTs, ZTE can meet the access demands of different
PON technologies provide the basis for advanced service delivery.
With complete solutions, ZTE is well positioned to meet the
high-capacity demands in different fiber broadband access markets.