Application of Ethernet Technologies to FTTH Access Systems

The number of the high-speed Internet access users, those with broadband access, has reached 20 million. Of particular interest is the significant growth introduction number of fiber-to-the-home (FTTH) access users. Commercial FTTH in Japan started in 1997 and provides residential planeold-telephone-service (POTS) and CATV signals transmission by using a combination of synchronous-transfer-mode (STM) passive optical network (PON) [1] and sub-carrier modulation (SCM) PON [2]. The main purpose of this deployment was to replace old metallic pairs with optical fiber access systems, however, the monthly subscription charges of POTS and CATV signal transmission could not, initially, cover the cost of system deployment. In 2001, a 10 Mbps bandwidth shared PON system [3] and a two-fiber point to point system were started for small business customers and multi-dowelling unit customers. Asymmetric digital subscriber line (ADSL) systems for residential users have had their transmission speed upgraded every six months; the current speed is over 50 Mbps in the downstream direction. With regard to the monthly subscription charges, they have been significantly reduced over the last five years. The competition between the multiple ADSL access service operators has sparked the remarkable growth in ADSL user number. However, the metallic pair’s attenuation with access loop length restricts the maximum transmission speed, users who want stable access have moved to FTTH access. From operators’ viewpoint, the capability of FTTH allows the provision of more advanced broadband applications, which are new revenue sources for the operators. Currently, in addition to telecom operators, major power utility companies and DSL service operators are providing FTTH access. The heavy competition among broadband access services is driving operators to deploy higher transmission speed systems, from 10 Mbps to 100 Mbps and