In a cable television sense, “the back office” grew directly out of the billing system. Billing systems create bills, yes. But usually they’re also the control knob for new service activations, device activations (set tops, cable modems, and VoIP units), customer care, collections, technician dispatch, and fleet management. And thats a partial list.
If you could put the back office in your hand for close inspection, you’d be looking at a glob of inscrutably entwined databases.
Backbone networks are usually characterized by their size (in thousands of miles of fiber) and capacity (Terabits per second, these days, which gets abbreviated Tbps, which isn’t equivalent to a tablespoon.)
In the first edition of this dictionary, the poster child for the “backbone network” was the @Home Network, a collaboration involving large U.S. cable operators that was owned by a partnership of Hearst Corp. and Tele-Communications Inc. Since then, @Home shut its doors, and participating cable providers started putting together their own backbone networks.
The range of radio frequencies used to convey telecommunications services. In cable TV networks, bandwidth refers to the sizeable spectral region between 5 MHz, and as high as 1 GHz (although most systems top out at 750 MHz, and a handful top out at 870 MHz.)
Lately, “bandwidth” seems to be gaining favor, conversationally, as a synonym for “capacity” and “throughput.” People talk about “high bandwidth” networks, to mean fat pipes. Or they’ll say “high bandwidth” to describe the speeds of their cable or DSL modems, versus “low bandwidth” to describe dial-up telephone connections. This isn’t incorrect, except to be the conversational equivalent of making an end from a means.
How is bandwidth related to spectrum? In a sense, “spectrum” is what you’re born with (5-750 MHz, in cable networks). “Bandwidth” is what you make of it: how you partition it, how you architect networks around it and how you compress the material riding over it.
Understanding cable bandwidth is like looking at a bookshelf. Let’s say it’s an organized shelf, with room for 750 slots — where the 750 correlates to the total bandwidth (in MegaHertz, or MHz) of most U.S. cable systems.
On the far left sit 18 skinny pamphlets. In bandwidth terms, each is about 2 MHz wide. That’s the upstream path, used to convey information from homes back up the network, to the headend. The contents of the upstream path use about 5 percent of the total shelf, specifically located between 5-40 MHz.
To the right of the pamphlets sit 83 hardbacks. Those are the analog channels — basic and expanded basic service. In bandwidth terms, each is 6 MHz wide. In total, the hardbacks use about two-thirds of the shelf, from 52-550 MHz.
(The gap between the upper edge of the upstream, at 40 MHz, and the lower edge of the analog zone, at 52 MHz, is a necessary cushion to prevent upstream and downstream channels from mixing with one another. In our bookshelf model, imagine a volume had been removed and never returned.)
To the right of the hardbacks is a mixture of books. Several are paperbacks. Some are those big, over-sized art books, with the striking photographs, that people always seem to give you when you’re out of town and don’t have time to get to a shipping store.
Together, the paperbacks and the art books are the digital channels, both standard definition and high-definition; broadcast-style and on-demand. Digital channels use about a quarter of the shelf, from 550-750 MHz. (Broadband Internet and voice-over-IP traffic, which is digital, rides here too, but well set them aside for this discussion.)
The “digital paperbacks” are the stuff of today’s digital tiers: Regular TV channels that are digitized and compressed, plus the goods of video-on-demand, subscription-on-demand, and all the other on-demands.
The big books, naturally, are the HDTV channels — gorgeous but, as airline attendants say, heavy and awkward.
The ration of paperbacks to art books depends on how many of each is on the lineup. The 200 MHz of bandwidth that resides between 550-750 MHz translates into about 33 channels in traditional widths of 6 MHz. That means there’s room for 330 or so digital channels (the paperbacks) and no HDTV (the art books). Or, there’s room for 99 HDTV channels, and no “standard definition” digital channels (the paperbacks).
The ultimate mix is usually some combination of both.
Usage: One of the primary concerns of any cable operator is whether there’s enough bandwidth for all the services that could be offered
This matters because more new stuff is always coming, but the shelf space that is bandwidth is poised to stay relatively static from here on out, with the possible exception of plant extensions to 1 GHz.
Reason: Cable providers spent a ton of money getting to 750/860 MHz. Wall Street knows it. Anything that looks like a big capital expenditure, from here on out, likely will be treated punitively by investors. But that’s okay. It means bandwidth management becomes more vigorous. Using the “shelf” analogy again (See “bandwidth”), it means organizing the shelves, rather than always adding more shelves.
• Moving pay-per-view channels from analog to digital
• Migrating local access and public, educational and government access channels to the digital tier
• Removing legacy, non-DOCSIS-based cable modems
• Converting from 64- to 256-QAM (quadrature amplitude modulation) in the distribution network
• Re-arranging how lasers and receivers are organized in the network, such that one laser feeds one group of nodes, instead of one laser feeding four groups of nodes
• Implementing switched broadcast video, to only send the channels a person requests, instead of sending all channels, all the time
• Expanding bandwidth to 1 GHz (which isn’t the same as “plant upgrade”)
Ethernet LAN (local area network) systems, such as those used in an office, also are baseband, as is a conversation carried over a phone wire. Cable operators don’t use baseband to transmit voice, video or data, simply because modulation techniques assist in sending signals farther.
Usage: “Charter’s ‘simultrans’ took analog baseband signals, converted them to a serial digital interface (SDI), which provided an uncompressed digital signal.”
It works like this: A television show is digitized into zeros and ones, grouped into specific “frames” of video. I-frames start the compression sequence, and serve as a reference point of “the first in the series.
“P” frames look at what elements are the same in the current frame and the previous frame, and “predict” what elements will be the same in the following frame. (The elements that are the same can be discarded, which is part of what makes the compress in compression.)
“B” frames look to the frame ahead and the frame behind, to further solidify what’s in a future frame.
Usage: “The digital encoding equipment transformed the movie into a collection of ones and zeros — the building blocks of binary code.”
Usage: Digital math: One byte contains eight bits. A kilobyte contains one thousand bytes. A Megabyte contains one million bytes. A Gigabyte contains one billion bytes.
The bit stream is the digital representation of a voice conversation, television picture or other piece of digital or analog content. It moves linearly along a medium.
Usage: “VOD servers output a bit stream consisting of compressed, encoded movies, which are decoded, decompressed and converted back to analog at the set-top box.”
A common example is to “vote someone off the island,” by pointing and clicking the TV remote at the part of the screen that illustrates the vote.
By contrast, “unbound applications” are service features that are invoked by pushing a specific button on the remote — “guide, for instance, or “menu.”
Usage: “The suits at the network devised a bound application that would let viewers weigh in instantly about their favorite stunts.”
Usage: “According to Bowick’s Theorem, cable modem users will soon enjoy double-digit downstream data rates.”
Note that your mileage may vary, so to speak, depending on the slowest link of a bridged network. For instance, if you have broadband Internet coming in to your cable modem at 5 Mbps, and you hook into an Ethernet bridge capable of 100 Mbps, that doesn’t mean you’ve suddenly got 95 more Mbps to play with. Throughput is only as fast as the slowest link.
Usage: “Modern-day hotel guests are accustomed to requesting from the front desk a wireless bridge to gain access to a local WiFi network.”
Here’s how we define broadband: The ability to deliver unlimited, simultaneous, high-quality video and voice services, as well as high-speed data links to the Internet, to as many devices as can be connected, over a single wire or wire/wireless combination.
In other words, “broadband” implies a network that carries enormous amounts of digital and analog information, at speeds of at least 1.5 Mbps downstream (to accommodate the FCC’s definition), such that connected customers can get simultaneous and unlimited access to video, voice and data services. That means fielding a phone call, while flipping channels on the TV and HDTV, and surfing the Internet, at high-speed — all at the same time.
“Broadband” tends to elicit debate over speeds. Precisely how fast “fast” is, remains in the eye-of-the-beholder. Some providers use the word “broadband” to describe a residential high-speed Internet access service that meanders along at a relatively pedestrian 200 Kbps. Others hold “broadband” to a higher standard that’s measured in megabytes per second.
But the disagreement over data rates is mere quibbling. Broadband is one of those terms that have been lofted into a higher realm of meaning altogether. For many, broadband refers to a set of capabilities, more so than a strict delineation of Internet data rates. The ability to summon up a commercial-free movie to the living-room TV set, pause it at will, and rewind to a key scene fits neatly under this definition of broadband. So does the ability to send a video clip of a child’s game-winning triple in Little League to her grandmother via a digital network.
From a cultural perspective, broadband also has its place in the lexicon. It’s a catch-all, digital-era tag designed to confer a certain hip, with-it sensibility surrounding network-delivered content and experiences.
Usage: “The broadband revolution is alive and well, and it’s coming soon to a home, neighborhood, office, school, hotel, airport, airplane, coffee house and college campus near you – if its not there already.” From a speech by Bruce Mehlman, Assistant Secretary for Technology Policy, U.S. Department of Commerce.
Ever send a document to a printer, shut off your PC, and wonder how the printer knows to keep on printing? It’s because the information was instantaneously sent to a memory buffer inside the printer. Buffers are also the reason you wait when loading a piece of Internet video: They’re being filled with the first few chunks of the digital video picture. As the video starts playing, the buffers continue filling up in the background, so that what you see is a reasonably continuous video flow. Buffers also come into play in digital set-top boxes, to hold large amounts of incoming, compressed video, without overwhelming the circuits that demodulate, decompress and convert those signals into analog.
Usage: “The buffer captured the news clip and then delivered the data at a rate my PC could handle.”
In cable, Cox Communications started the trend with its “triple play bundle,” which offered consumers a package of voice, video and high-speed Internet offerings. Subsequent tracking has shown that customers are far less apt to discontinue service when they purchase a bundled offering. Lately, the buzz of bundling is the addition of wireless, in some shape or form, to at least the voice and data portions of service bundles — something providers are calling the “quadruple-play.”
Examples include e-mail and Web page requests, where it doesn’t matter if the bits come back smoothly — just that they come back and can reassemble themselves into the piece of mail, or the requested page. By contrast, a voice conversation or a streaming video are designed for a smoother ride, so that the conversation or picture doesn’t stutter or exhibit interruption.
Usage: The digital composition of e-mail messages and Web pages usually can be delivered in a bursty fashion, without any apparent degradation.
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