Verizon's last mile
A sidebar accompanying our May 2007 cover story, "Testing brings home telco TV."
Martin Rowe, Senior Technical Editor -- Test & Measurement World, 4/30/2007 12:54:00 PM
Read the accompanying May 2007 cover story, "Testing brings home telco TV."
Verizon’s fiber-optic service, known as “FiOS,” consists of an FTTH network. Voice, video, and data travel over three wavelengths—1550 nm, 1310 nm, and 1490 nm. The “last mile” FTTH access network connects an ONT outside a customer’s house to an OLT at a CO. Verizon uses broadband passive optical network (BPON) and in some places gigabit PON (GPON) technology between OLTs and ONTs at subscribers’ homes (Figure A).
 |
|
Figure A. Fiber to the home uses three bandwidths: one for broadcast video, one for upstream voice, data, or video on demand, and one for downstream voice, data, or video on demand. |
Broadcast video in both analog and digital forms travel over the 1550-nm wavelength in a 55.25-MHz to 870-MHz band where each channel uses 6 MHz. Broadcast TV isn’t, as many believe, sent using IPTV. The network converts all broadcast TV channels from MPEG over IP to their original analog or digital forms at the video hub office. Verizon uses QAM to transmit digital TV channels and standard NTSC video for the analog channels. About thirty to forty 6-MHz analog channels travel over the fiber. Analog channels let subscribers connect TVs to the network without an STB. Verizon does use IP for voice, data, and VoD services.
Each BPON or GPON link from an OLT passes through a splitter to the subscriber’s home. Thus, the 32 subscribers share the BPON or GPON link’s bandwidth (GPON can handle 2.4 Gbps, so each home gets at least 80 Mbps). At first, Verizon installed BPON OLTs and ONTs, but the company soon realized that subscribers would demand more bandwidth as they watched more VoD, which requires about 15 to 20 Mbps per video stream.
For homes without FiOS, Verizon’s line of demarcation between its network and the customer’s premises ends at a network-interface box. The customer is responsible for wiring. With FiOS, Verizon’s responsibility extends to STBs, phones, and computers inside the home.
 |
|
Figure B. An optical network terminal connects the fiber-optic line to customer premises equipment (TVs, phones, and computers). |
When a person subscribes to Verizon FiOS, technicians will come to the customer’s home and install the ONT, router, STBs, coax, and Ethernet cables. Network components remain the property of Verizon. Customers just rent them.
