Realization of economical, high-speed, broadband FTTHGigabit Ethernet-PON systemNTT Access Network Service Systems Laboratories

The Gigabit Ethernet-PON system is an optical system that can economically provide up to 1 Gbit/s broadband access, and is expected to be used for high-speed broadband services in the future. The system can simultaneously provide the best-effort Internet access, quality-guaranteed content distribution and VoIP, etc., by using bandwidth control and priority control technologies. The bandwidth control dynamically allocates transmission bandwidth of the access segment according to the subscriber's individual usage conditions, while the priority control preferentially transfers traffic requiring low latency such as VoIP. In addition, its specification takes into account the optical carriers’ wavelength allocation between the Gigabit Ethernet-PON and video transmission systems, enabling simultaneous transmission of data and video service signals.

• An access system with access speeds up to 1Gbit/s
• When 32 subscribers are connected to a single PON system, the allocation speed per subscriber is approximately 30 Mbit/s (fair allocation)
• Economical as it enables up to 32 subscribers to share optical fiber and facilities in the central office.
• Maximum bandwidth settings can mitigate the impact of heavy users
• Compliant with IEEE802.3ah for future multi-vendor interoperability
• The system is highly compatible with Ethernet-based services because it transmits Ethernet frames directly over the PON section.
• Optical wavelength division multiplexing technology enables simultaneous data transmission and video distribution over a single optical fiber.

1. PON technology
A single fiber-optic cable can be shared by up to 32 subscribers. Each subscriber can communicate at up to 1 Gbit/s when the network is vacant and at a guaranteed minimum speed (i.e. 30 Mbit/s) when the network is congested.

2. Wavelength division multiplexing technology
Upstream and downstream data signals are transmitted in a single optical fiber by optical carriers of different wavelengths (1.31 μm and 1.49 μm). In addition, its specifications make it easy to add the 1.55 μm wavelength carrier for video distribution services. Because the data transmission and video distribution signals are multiplexed by carriers of different wavelengths, they can be delivered simultaneously without affecting each other.

3. Dynamic bandwidth allocation technology
The minimum guaranteed bandwidth, maximum available bandwidth, and latency class settings make it possible to control the bandwidth and latency required for each subscriber or service. This enables detailed service design and service delivery.

4. Priority control technology
The VLAN priority value on the Ethernet frame allows for priority control of traffic within a subscriber on a per-service basis. Specifically, for subscribers who use voice, video, and Internet access services at the same time, voice data that requires low latency can be transmitted first, followed by video data, enabling the remaining bandwidth to be used to transfer data for the Internet access on a best-effort basis.

PON
Abbreviation for "Passive Optical Network." A tree-topology network in which optical carriers are diverted in multiple branches without being converted to electricity. Because its transmission equipment and optical fibers are shared among multiple subscribers, it is quite economical.

NTT Access Network Service Systems Laboratories - Optical Access Systems Project