Fiber-to-the-premises

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Fiber-to-the-premises (FTTP) is a network upgrade that provides residential and SOHO customers with true broadband services (i.e., voice, data, and video). FTTP has the potential to carry the telephone companies into the entertainment arena.

FTTP is a catalyst for new services and applications in the telecom industry. To support these services and applications the network infrastructure will be upgraded as well. This upgrade allows telephone companies to compete with the cable and satellite providers for consumer entertainment dollars.

The FTTP last mile architecture and the accompanying network infrastructure buildout is the start of a full network upgrade. The upgrade moves the telephone companies from a centralized, wire-based network to a distributed, fiber-based network. The FTTP system can be used to provision any of the existing voice and data products, as well as future applications.

FTTP Architecture

BPON

The visual depicts one version of an FTTP network. Several flavors of FTTP have been, and are still being, defined. These include BPONs, GPONs, and EPONs. The PON in the name indicates the technology is a passive optical network. PONs have the potential to be very low maintenance networks as the only active components are the service provider or customer locations. The B in BPON is for broadband. This architecture is based on ATM for voice and data services and supports regular television distribution. EPON is Ethernet-based and GPON is Gigabit Ethernet-based.

The visual shows a BPON with traditional television services being delivered to a WDM multiplexer. Voice, Internet access, and IPTV services are all delivered via the service provider IP network.

The FTTP architecture comprises four primary components: the optical line termination (OLT), the optical network terminal (ONT), the optical fiber, and optical splitter/combiners.

FTTP Architecture

The OLT is the head end device for the FTTP system. It interfaces the fiber transmission system to the central office components (class 5 telephone switches, packet switches, and video gear). The OLT might have an integrated PON coupler to combine an optical video source. The OLT also supports interfaces to the telephone system’s operational support system for testing and maintenance.

The ONT is located at the customer premises. The ONT is the fiber-to-wire media converter, services demultiplexer, and wavelength splitter. The ONT supports POTS interfaces, Ethernet interfaces, and video interfaces.

The fiber-optic transmission cable is a single-mode fiber supporting up to 32 ONTs. Fiber runs of up to 65 km are possible for the FTTP systems.

The final component is the PON splitter/combiner unit, which provide the wavelength and fiber multiplexing and demultiplexing that is the heart of the FTTP systems. The splitter/combiner interfaces to at most 32 residential fibers/wavelengths and multiplexes them to the single fiber running from the central office.

FTTP vs. DSL

FTTP is viewed as a replacement for digital subscriber line (DSL). However, this is a misconception because the two are not mutually exclusive. They are complementary products that offer the consumer a variety of services to meet all the pocketbooks of a community. The high-end users will select FTTP, and the casual users will select DSL; POTS will be available for the remaining users.

The FTTP architecture can support the deployment of DSLAMs and remote telephone terminals at the community “curb.” The overlay deployment model defines such an approach, offering high-speed VDSL (and POTS) to houses without fiber.

The advantage of the FTTP architecture is that it modernizes the telephone outside plant. It allows any type of service to be deployed to a very large customer base at a realistic operational cost.

As FTTP is deployed, the DSL equipment currently in place can be reused in other areas, increasing the reach of broadband services.

FTTP Diagram

FTTP Diagram

The visual shows the elements of the FTTP architecture. This is the full build model showing fiber-to-the-customer locations. The PON network elements (splitters and combiners) are located in the fiber distribution hubs and fiber distribution terminals.

In the central office, the optical line terminal is feed by SONET fiber from an ATM switch in a manner similar to the existing DSL architecture. Interfaces for voice services (TR-008, GR-303, and TR-57) connect the OLT to the class 5 switch. Data interfaces for the element management system (operation support system) provide a test and maintenance capability. The TV feeds are accepted in the optical domain, the signal is busted with a fiber amplifier (EDFA), and combined into the PON system.

At the customer side, optical network units can be deployed in single family units, multi-family units, single business units, and multi-tenant units. The sizing of the ONT is based on the number of interfaces at each of these units.

Advantages of FTTP

The principal advantage of FTTP systems is the amount of bandwidth available per subscriber. The BPON systems offer up to 155 Mbps per household for voice and data services and a full video capability on top of that. This offers a speed 600 times faster when compared to voice channel data services.

For the service provider, other than new revenue streams, FTTP offers an upgrade avenue for the outside plant. This upgrade will reduce the operational expenses of the outside plant when compared to the existing broadband systems. The savings come from the lower power requirements of the passive devices and the increased mean time between failure of the equipment.

These advantages are tempered with a technological risk. FTTX systems have been around for a decade (X being home, curb, hut, etc.), but few of them have been successful in both a technological and business perspective. The FTTP systems show promise, but only time will tell.

PodSnacks

<mp3>http://podcast.hill-vt.com/podsnacks/2007q2/fttp.mp3%7Cdownload</mp3> | Fiber-to-the-premises (FTTP)
<mp3>http://podcast.hill-vt.com/podsnacks/2007q2/fttx.mp3%7Cdownload</mp3> | Fiber-to-the-X (FTTX)