Access System Technologies for Service Diversification
Yukihiro Fujimoto · NTT technical review · 2016
Review 1. Advances in access services and system technologies 1.1 Initial commercial FTTHThe fiber-to-the-home (FTTH) service in Japan is currently being used by more than 26 million users.Its growth has followed the rapid adoption of Internet access, and it is now a key communication infrastructure.Commercial FTTH service started in Japan in 1997, and its system technologies have greatly advanced over the last 20 years or so.The initial FTTH services provided analog/ISDN (integrated services digital network) phone system communication and analog multi-channel video distribution.Two technologies dominated this period: synchronous transfer mode passive optical network (STM-PON) systems for the telephony-based services and SCM-PON (sub-carrier multiplexing PON) for the video distribution services.The access system transferred both services over the same optical fiber by using wavelength division multiplexing (WDM) [1].A PON with a 32-branch splitter was adopted as the physical topology of the access network.The first FTTH systems were rather slow, about 16 Mbit/s, but this was acceptable since the dominant service was telephony.However, the original idea of providing access services via a WDM-based PON system carrying optical signals corresponds to the current FTTH (Fig. 1). FTTH broadband accessThe advent of the new millennium in 2000 saw a major change to access services.The conventional telephony service was replaced by Internet access as the dominant traffic source.In early 2000, we developed and introduced a system that could take full advantage of the STM-PON described above to realize bandwidths of up to 10 Mbit/s.This move was driven by the need to eliminate the speed restrictions of ADSL (asymmetric digital subscriber line), a highspeed metallic communication system.In 2002, we developed the B-PON (broadband PON) based on ATM-PON (asynchronous transfer mode PON) for data communication [2].The next advance was the introduction of the Gigabit Ethernet-PON (GE-PON) based on Ethernet technology in 2004 [3].Consequently, access system speeds rose from 12 Mbit/s to 1 Gbit/s in just a few years.The major enabler has been the adoption of high-speed local area network (LAN) technology, which has become very cost-effective with the release of international standards such as those specified by the Institute of Electrical and Electronics Engineers (IEEE) and the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T), as well as the subsequent commercial Access System Technologies for Service Diversification