EPON vs GPON

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.

FTTx Deployments
Many carriers are already deployed 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

Technology comparison
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).

Costs comparison
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.