A Comparison between GPON and EPON

The access layer network is a fundamental platform for the deliveryand termination of various services. As subscribers to broadbandaccess services continue to grow rapidly, there is an ever-increasingdemand for broadband access bandwidth. As an ideal medium, opticalfiber provides high-speed and high-bandwidth multi-servicetransmission. Fiber access, which offers many advantages indelivering next generation services, has become one of the keytechnologies 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-basedapproaches promise an attractive way to deliver high bandwidth. Infact, FTTH solutions based on EPON/GPON technology are becomingmore and more popular all over the world, improving end users'experience by delivering high-speed triple play services.

FTTx DeploymentsMany carriers are already deploying PON FTTx network architecturesto eliminate the last mile bottleneck when providing high bandwidthservices to end users.

Asia is the major action point for EPON, accounting for 80% ofworldwide PON subscribers. In Japan, there are more than 7 millionFTTx subscribers at the end of 2006, and is projected to grow to morethan 17 million by the end of 2010. By the end of 2006, EPONdeployments represent about 80 percent of the worldwide FTTHmarket. The remaining 20 percent of the FTTH market is based onGPON, BPON, which are opted by North American carriers such asVerizon and SBC, and point to point (P2P), which is favored by France.

EPON has massive deployment while GPON, as the next leadingtechnology, is still in its early stage of development. As fiber access is

poised for strong growth, carriers can choose between the two mainPON standards: EPON and GPON.

EPON vs. GPON

Technology comparison

Both are accepted as international standards. They cover the samenetwork topology methods and FTTx applications such asFTTH/FTTB/FTTO/FTTB; incorporate the same WDM technology,delivering the same wavelength both upstream and downstreamtogether 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 802.3ahEthernet in the First Mile standard that is now merged into the IEEEStandard 802.3-2005. It is a solution for the "first mile" optical accessnetwork. GPON, on the other hand, is an important approach toenable full service access network. Its requirements were set force bythe Full Service Access Network (FASN) group, which was lateradopted by ITU-T as the G.984.x standards–an addition to ITU-Trecommendation, G.983, which details broadband PON (BPON).

Costs comparisonxPON, as a FTTH technology, is an ideal solution to deliver last-milebroadband access. The optical line terminal (OLT), optical networkunit (ONU) and optical distribution network (ODN), which comprise aPON 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 andcabinet with EPON is similar to that with GPON.

The cost of OLT and ONT is decided by the ASIC and optic module. TheGPON chipsets available in the market are mostly based on FPGA,which is more expensive than the EPON MAC layer ASIC. There areonly several chipset vendors who can provide GPON chipsets, and it is

not likely that the price of GPON equipment can decline rapidly. Theoptical module of GPON is also more expensive than EPON. WhenGPON reaches deployment stage, the estimated cost of a GPON OLT is1.5 to 2 times higher than an EPON OLT, and the estimated cost of aGPON ONT will be 1.2 to 1.5 times higher than an EPON ONT.

ZTE's View on GPON and EPONEPON is the dominant FTTH solution in Japan, Korea, China and otherAsia-Pacific countries, meeting the demand for services such ashigh-speed Internet access, VoD, IPTV, and etc. In other countries,especially in America, GPON is the preferred choice, as BPON and ATMinfrastructure is more prevalent in this area, and GPON can coexistwith the legacy PON systems. That explains why EPON appears togain an upper hand in the Asian market where BPON is not widelyused.

As such, ZTE thinks that EPON and GPON will take their own shares inthe growing market in the next few years, and it is hard to say whichtechnology will replace the other in the near future.

ZTE, with its deep insight into network evolution, has launched bothEPON and GPON systems. The ZTE EPON and GPON systems supporthigh quality multicast and dynamic bandwidth allocation (DBA), andprovide VoIP, IPTV, CATV SDTV, L2 VPN and TDM leased line services.

EPON and GPON may be applied in different situations, and eachoffers its own advantages in subscriber access networks. EPONfocuses on FTTH applications while GPON focuses on full servicesupport, including both new services and existing traditional servicessuch as ATM and TDM.

The ZTE xPON solution provides a uniform platform for both EPON andGPON standards, supporting EPON and GPON mixed inserts in oneframe and enabling flexible networking applications.

The ZTE EPON/GPON system includes the ZXA10 C200/C220 OLT andD/F series terminals. The ZXA10 C200 features small-to-mediumcapacity, compact structure, high-density, high bandwidth and

scalability; the ZXA10 C220 delivers medium-to-large capacity. Withvarious kinds of ONTs, ZTE can meet the access demands of differentusers.

PON technologies provide the basis for advanced service delivery.With complete solutions, ZTE is well positioned to meet thehigh-capacity demands in different fiber broadband access markets.