The largest phone companies now building networks that will carry video services — SBC Communications Inc. and Verizon Communications Inc. — will travel along two different technological paths.
While SBC plans to deploy an Internet protocol-based, switched-video network, Verizon will launch its video service over a fiber-to-the home architecture.
Verizon’s FiOS platform is drawing understandable comparisons to cable’s basic transport platform, but there are points of differentiation that make the telco’s deployment unique.
First, it will use a combination of supertrunking and edge modulation in the transport plant. Second, it is creating two national superhubs to receive and encode video signals, before sending them to individual regions using its national backbone.
Third, Verizon will actually transmit video-on-demand content via an IP stream within its overall data stream, and not as part of its separate video broadcast channel.
MOCA CONNECTION
Ironically, the cable industry is starting down the path of national encoding and distribution of channels as it begins to deploy digital simulcasting.
And remember the MOCA Alliance, the multimedia-over-coaxial cable group that’s addressing home networking? Verizon plans to use its specification to deliver that VOD content throughout the home, using an Ethernet connection.
It all adds up to “cable” plant, but with plenty of Verizon-specific attributes. Verizon has chosen Motorola Inc. is its systems integration and as supplier of much of its headend gear and set-top boxes. Microsoft Corp. will furnish middleware and its TV Foundation Edition platform. TVN Entertainment Corp. has been tapped for VOD content and delivery.
Verizon is using a host of suppliers for fiber transport.
Still to be publicly announced: the VOD server, edge modulation system and several other hardware components.
The company is building two national superheadends, in locations yet to be announced, said Greg Evans, vice president of services and access technologies in Verizon’s national technology group. Those two headends will be geographically disbursed.
Motorola is the main gear supplier for those superheadends, which will use MPEG-2 (Moving Picture Experts Group) encoding.
Video signals will be transported from the superheadends to regional video hub offices using Verizon’s national backbone network, Evans said. The syncrhronous optical network (SONET) uses Gigabit Ethernet over redundant SONET rings. “We have access to two counter-rotating rings,” Evans said.
SUPERHEADENDS
The national channels will be encoded at the superheadends. Local broadcast stations, public, educational and government access channels, the Emergency Alert System and other local fare will be encoded and inserted at regional video-hub offices.
Verizon will use two different technologies to distribute those signals: traditional supertrunking analog transport and edge modulation.
“We’re looking for diversity, so we can have high reliability and availability,” Evans said.
If there is not much free fiber — or if the end points are distant from one another — edge modulation is a good option, he said. In a fiber-rich environment that covers relatively short distances, supertrunking can be a better option.
The national and local video will be assembled in video-hub offices, which tend to serve 75 to 100 telephone central offices, Evans said. Verizon’s central offices reach an average of 14,000 homes.
Verizon will use passive optical networking (PON) architecture for broadcast-video transport to the home. Signals originate from an optical-line terminal (OLT) at the hub office, and are sent to optical-network terminals (ONT) on the side of the home.
The OLT sends out voice and data services on one light wavelength to the ONTs. Both devices are supplied by Advanced Fiber Communications. One PON serves about 32 ONTs.
The ONT receiver has an RJ-11 jack and RJ-45 Ethernet plug. Telephone signals go through the jack to the inside phone, while the data signal travels via Ethernet cable direct to the consumer’s PC. No data modem is needed.
The ONT has the ability to send a lambda wavelength upstream, for return voice and data service, Evans said.
The broadcast video is sent by injecting a third wavelength in the PON architecture. The wavelength bandwidth is 870 MHz, said Evans, at the upper end of bandwidth capacity for most cable plants. The ONT also has a standard coaxial interface — signals traveling over coaxial cable to the Motorola set-top box.
The voice-and-data path has a 622-Mbps transmission capacity. Verizon will offer VOD within that pipe, Evans said. VOD servers will be placed in video hub offices. VOD content will be streamed through the data backbone network.
Motorola plans to use home-networking technology from the MOCA Alliance to distribute VOD content from the ONTs to each set-top in the home.
VOD OVER IP
In that sense, Verizon will be using the IP platform to deliver VOD content. “For VOD, there is an economic issue. It’s the most cost-effective way to deliver VOD traffic,” he said. The MOCA technology will multiplex the Ethernet signal over cable and distribute it throughout the house.
Initially, Verizon will deploy MOCA dongles, since that specification hasn’t been built into current set-tops, Evans said. Eventually, MOCA will be built into both set-tops and ONTs, he said.
Seven companies are supplying Verizon with fiber: Corning Cable Systems, ADC Telecommunications Inc., Preformed Line Products Co., Tyco Electronics, Sumitomo Electric Lightwave, Pirelli Communications Cables and Systems North America, and Fiber Optic Network Solutions.
