PDF of this tutorialTransmission standards utilized in FTTH networks are based on ATM and Ethernet technologies. Carriers are extremely familiar with both technologies, which support a variety of services. Today, most PTP networks use Ethernet technology and are governed under Institute of Electrical and Electronics Engineers (IEEE) 803.2ah standards. PTP networks are simply an extension of legacy Ethernet used in metropolitan and enterprise spaces and extended into the access network. Bandwidth rates are only limited to the transmitter type at the CO/HE and the home. The majority of municipally owned and shared FTTH networks and early FTTH deployments in Japan utilized PTP networks.
PONs provide a wide array of technology and protocol choices for the carrier. The full-service access network (FSAN) initiative oversees the development of PONs. Comprised of more than 20 global carriers, the FSAN works with leading vendors to agree on common technology platforms for delivering converged services. The FSAN, not a standards organization, submits recommendations for adoption to the International Telecommunications Union (ITU). Figure 6 provides a complete breakdown of the PON protocols and the respective capabilities.
Earlier PON deployments utilized ATM PON (APON), which evolved into broadband PON (BPON).
| BPON | EPON | GPON | |
| Standard | ITU-T G983 | IEEE803.2ah | ITU-TG.984 |
| Bandwidth | Downstream up to 622 Mbps Upstream 155 Mbps |
Up to symmetric 1.25Gbps | Downstream up to 2.5Gbps Upstream 2.5Gbps |
| Downstream λ (nm) | 1490 and 1550 | 1550 | 1490 and 1550 |
| Upstream λ (nm) | 1310 | 1310 | 1310 |
| Transmission | ATM | Ethernet | ATM, Ethernet, TDM |
Broadband PON is governed by ITU G.983. The A/BPON protocol is characterized by having two downstream wavelengths and one upstream wavelength. The 1550 nanometer (nm) and 1490 nm wavelengths are used for downstream traffic, with the 1490nm channel typically an IP channel for voice and data service. The 1550nm channel will be used for a radio frequency (RF) or IP video overlay. Providing 622 Mbps shared electronics are able to dynamically provide 20 to 30 Mbps per subscriber. Time division multiple access (TDMA), recommended by FSAN, is used for all down/upstream traffic.
An alternative to A/BPON networks is Ethernet PON (EPON), governed by IEEE 803.2ah. EPON only uses two wavelengths and exclusively uses IP. The 1550 nm wavelength is used for downstream traffic, and the 1310 nm wavelength is used for upstream traffic. Capable of 1.25 Gbps in shared bandwidth, EPON under "best-effort" conditions provides for 100 Mbps but typically provides for bandwidth of 30 to 40 Mbps. GigaEthernet PON (GePON) can increase shared bandwidth to 2.5 Gbps.
Broadband PON has evolved into Gigabit PON (GPON) to address bandwidth and protocol limitations. Capable of up to 2.5 Gbps shared bandwidth among 32 users; GPON utilizes the same wavelength plan of BPON. It is governed under ITU standard G.984 and provides for protocol flexibility across ATM, Ethernet, and TDM platforms.
