Home Networking Glitz , CES Grit
by Leslie Ellis // January 22 2001
Anyone who ever attempted to track a technology through three days at the Consumer Electronics Show, followed by two days of the SCTE’s Emerging Technologies conference, knows that the contrasts can be just as interesting as the quest.
Such was the case with home networking glitz and grit at this year’s back-to-back technology events. At CES in Las Vegas, suppliers smoothly clamored around whichever home network type they’d chosen to endorse. There are several, which is part of the problem. In the digital glamour of it all, the home network somehow became a foregone conclusion.
The CES digital glitz showed stoves that solicited recipes from the Internet. Alarm clocks that tolled custom MP-3 music or Internet newscasts from other networked sources. Plasma displays framed in wood, like a picture, and hung on simulated residential walls to display remotely stored artwork or photographs.
Home networking matters weren’t so blasé at Emerging Technologies in New Orleans, where cable technologists absorbed the technical grit on its many complexities. Technology issues around home networks are plentiful: Security, so that a shared apartment wall doesn’t make unwitting spies out of neighbors using wireless networks. Frequency allocation, so that microwaves and klystron lights, soon to become more prevalent in public and office buildings, don’t interfere with wireless home networks. And, debate lingers over which device becomes the head unit for the home network – the set-top, a souped-up cable modem, or a wholly new gateway unit.
Through it all was the niggling issue of how to support what will assuredly be a wide mix of home network types chosen by cable customers. Here’s a distillation:
Ethernet. Chances are, if you peer around behind your office PC to see how it’s connected to your local area network, you’ll see a thick wire attached to a connector that’s slightly wider than an RJ-11 phone jack. The wire is known as “category 5,” the connector is RJ-45, and you’re on either a 10 Mbps or 100 Mbps Ethernet connection.
Most existing home networks are Ethernet-based, and were installed by early adopter types to share computer peripherals: The laser printer, back when they were really expensive, or the scanner. The problem with settling on Ethernet as a going-forward strategy to interconnect home entertainment, computing and appliances is that it usually violates the “no new wires” rule. Ethernet, as a rule, works better over the “cat 5″ grade of wire. Most existing residences don’t have it.
HomePNA. The “PNA” stands for “Phone Network Alliance,” and is a consortium of 70+ companies rallying around the use of telephone wires to distribute information in a home network. The earliest work from this group is already on sale today – HPNA 1.0, which delivers data to connected devices at a speed of about 1 Mbps. Version 2.0 comes out this year, and delivers 11 Mbps. The plus is that most homes already have telephone wires nested in the walls, which means no new wires are required.
Wireless home networks: Wireless proponents tend to swirl around one of three types: Bluetooth, HomeRF, and 802.11b, an IEEE standard that is starting to become known as “Wi-Fi.” Each has more than 70 supplier proponents.
Bluetooth is slowest – around 768 kbps – and cheap, and is good for short-range stuff, like computer speakers that don’t need wires to play sound, or communication between PDAs and cell phones. Wi-Fi is faster (11 Mbps), more expensive, and spans longer distances (300 feet). HomeRF is in the middle – about 1.6 Mbps now, rising to 10 Mbps next summer. All three will face security and interference issues.
Powerline: Another multi-supplier consortium, “HomePlug,” aims to make existing power wires the distribution media of choice for home networks. Long a dream but never fast enough to do anything substantial, the latest group of powerline proponents aims for 10 Mbps this year.
Why doesn’t somebody just build a box that includes every type of home network, and be prepared for whatever consumers buy? It’s happening. Intel Corp. is working on one, as is Boston-area startup Ucentric Systems, among others. (Note that there’s serious lexicon confusion around this device. Some call it a “residential gateway.” Others call it a “home server” or a “home media gateway.”)
Regardless of what name it ultimately takes, this sort of box makes sense, but simultaneously poses strategic risk. It has to do with the links to the broadband service provider. Most gateways have two: Cable, and DSL. What if the bundled customer happily interconnects all the stuff in the house to the gateway, then decides to switch to DSL? It’s a one wire change, and you’ve just lost a good multi-pay customer. Of course, the converse is also true.
Me, I’m still holding out for the group that can sync my alarm clock with the coffeepot, so that if I happen to hit “snooze” a few times, for nine more minutes of sleep, I don’t awake to burnt coffee.
This column originally appeared in the Broadband Week section of Multichannel News.
Sizing Up VOD: Architecture, Sizing and QAM
by Leslie Ellis // January 08 2001
As the year of video on demand opens, it seems timely to respond to a mailbox-full of inquiries about the “hows” of VOD technology, architecture sizing, and related modulation implications.
If cable providers do what they’ve said they’ll do this year – lead interactive services with a fairly hefty push on VOD rollouts – then VOD will become the industry’s first major foray into session-based services. Watch for Time Warner to be the most active, igniting as many as half of its 38 regions with VOD by the end of 2001. AT&T Broadband, Comcast, Cox, Charter and the rest of the pack plan to be similarly aggressive in ’01 VOD launches.
Getting ready for VOD starts with understanding how much of what you’ll need, in server storage space, headend equipment, and bandwidth capacity.
If you believe that VOD simply requires servers and receptive set-tops, think again. There is more.
At the least, to properly offer VOD, you need: Video file servers; channel upconverters (to take the raw output of the servers and put it on a tuneable channel); quadrature amplitude modulation (QAM, pronounced “kwahm,” a commonly used digital modulation technique in cable); security methods; and set-tops capable of handling rentable VOD content. On the back-end, you need hooks into your billing software, to collect rental fees.
An architectural rule of thumb for VOD modeling is to begin with fully saturated homes-passed by cable services, on a per-node basis. Say you’ve already built your system to run fiber out to nodes serving 500 customers, and that, ultimately, you expect 80% of those homes to take basic cable services. That yields a starting point of 400 customers.
Next, assume that half of those homes will ultimately take a digital box. You’re up to 200 VOD-capable homes, over time. (If you start with your current digital penetration number — 20 to 30% — you run the risk of under-sizing the network’s future VOD needs, which will cost you later.)
Calculating how many simultaneous VOD streams you’ll need comes next. Currently, the thinking is to assume that at any given time, one in ten people (or 10%), will opt to watch movies at the same exact time. Using that math, you’ll need to organize equipment and bandwidth to serve 20 concurrent VOD video streams.
(It should be noted, at this point, that straight math doesn’t always correlate to actual human actions. Think of your neighborhood. Maybe you rent one or two videos each weekend. But chances are, everyone in your neighborhood doesn’t rent flicks with the same regularity. In this writer’s house, for example, about 2 films are rented every two or so months, then get returned well past the due date. That creates a bit of domestic debate over who goes to Hollywood Video the next time, because each subsequent trip necessitates stopping at the ATM to pick up enough cash to pay the late fees.)
We’re up to bandwidth sizing for 20 VOD streams. This is where digital modulation comes into play. Modulation, simply put, is the process of imprinting information onto a communications carrier, so that it can get from one place (the headend server) to another (the VOD-capable set-top). Cable currently uses a digital modulation technique known as 256-QAM, which equates to about 38 Mbps of useable bandwidth, per 6 MHz channel.
Handily, each digital video film that’s been compressed with MPEG-2 uses roughly 3.8 Mbps of bandwidth. Divide 256-QAM’s capacity (38 Mbps), by MPEG-2′s data rate (3.8 Mbps), and you get 10. This means you can stuff about 10 films into one, 6 MHz cable channel. If you need 20 simultaneous VOD streams, you need two 6 MHz channels, assuming 10% peak, simultaneous usage by VOD customers.
The process of placing digitized content into the HFC system for receipt by digital boxes varies, predictably, from manufacturer to manufacturer. Simply put, what needs to happen to get a VOD movie to a home is to:
1. Digitize and compress it (MPEG-2), 2. Store it (the work of companies like Concurrent Computer, Diva Systems, nCUBE and SeaChange International), 3. Upconvert the output of the server to a specific channel location, 4. Wrap it with conditional access and encryption safeguards against theft, 5. Multiplex (smoosh) it onto a carrier using 256-QAM, and 6. Send it to the digital set-top box.
This can happen in varying order. Both of the industry’s major suppliers, Motorola and Scientific-Atlanta, ultimately execute the same functions, but do so in different order.
As VOD becomes reality, instead of models and tests, the name of the game will be scale – the ability to augment the model with more serving capacity, and more 6 MHz channels dedicated to VOD (thus, more QAMs). Until then, the models and equipment lists cited here should yield at least an intellectual start to the process.
This column originally appeared in the Broadband Week section of Multichannel News.