When is broadband broad enough? [Telecom]

Since I've been putting effort into trying to obtain faster Internet connectivity for a certain residential neighborhood, plus reading about Google's 1 GB proposals, broadband initiatives from the government, etc., let me raise the meta-question:

What's the target bandwidth that seems reasonably needed for an average, normal single-family residential connection, at present or in the reasonably foreseeable future?

Or alternatively,

Are there any foreseeable applications or capabilities for which this same average, normal single-family customer will really want or need a 1 GB connection in the reasonably foreseeable future?

[Note the "average, normal, single-family" wording, which is meant to exclude any and all special cases where someone is running some kind of heavily used server or performing other commercial-type functions that consume massive amounts of bandwidth.]

My own experience here is with a household containing several active Internet users, including two semi-professionals doing extensive computing, emailing, and web surfing, plus occasional file transfers and document downloads.

And, the experimental fact seems to be that we got along pretty happily for a decade with a 400 kB DSL connection; and are now more than happy with a 5 to 10 MB connection in one location for most of the year, and a

2 MB connection in another location for the rest of the year. (But, we don't do any streaming video watching; have been a "TV-free" household forever.)

My guess is that 95% of this hypothetical "average normal single-family residential market" would be fully happy for the foreseeable future with a solid full-time 10 MB connection, if they also had cable or TV for video and occasionally batch-downloaded films or videos from Netflix or the like.

If you take away the separate TV or cable connection and put everything on a single Internet connection, seems to me a full-time 100 MB (maybe

200 MB?) connection would still provide everything they could reasonably want.

And I have a hard time seeing how they could either want or need 1 GB for any reasonably foreseeable future need (no matter how much of their data or computing goes into "the cloud").

None of this is to argue against running, for example, a direct FTTH cable into to every residence you can, thus providing essentially unlimited future connectivity, even if only 10 to 100 MB of this capacity is initially enabled.

But even having done that, what's the bandwidth at which you've massively exceeded the "information absorption or transmission rates" for most reasonable single-family connections?

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....... Let's get this right once and for all.

The correct use of the term "Broadband" has nothing whatsoever to do with how big a data pipe is - or anything to do with data at all, really.

"Broadband" in the Internet sense only applies to physical connections that use technology that carries more than one diverse service.

ADSL with an analogue telephone service on the same wire is "Broadband", ADSL on its own is NOT "Broadband", if anything it is a "Baseband" service.

The telecoms term "Broadband" has been hijacked by people who do not know better for defining general high speed data/Internet connections.

Reply to
David Clayton

(Moderator snip)

My wife and I am presently both on-line. She is streaming Countdown with Keith Olberman while I am typing here. We have 3mps internet. This serves all our need.


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Reply to
+--------------- | Let's get this right once and for all. +---------------

Yes, let's. And it's not what you think! ;-}

+--------------- | The correct use of the term "Broadband" has nothing whatsoever to do with | how big a data pipe is - or anything to do with data at all, really. | | "Broadband" in the Internet sense only applies to physical connections | that use technology that carries more than one diverse service. +---------------

ORLY? ;-}

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Broadband Internet access, often shortened to just broadband, is a high data rate Internet access-typically contrasted with dial-up access using a 56k modem. ... Although various minimum bandwidths have been used in definitions of broadband, ranging up from 64 kbit/s up to 2.0 Mbit/s, the 2006 OECD report is typical by defining broadband as having download data transfer rates equal to or faster than 256 kbit/s, while the United States (US) Federal Communications Commission (FCC) as of 2009, defines "Basic Broadband" as data transmission speeds exceeding 768 kilobits per second (Kbps), or 768,000 bits per second, in at least one direction: downstream (from the Internet to the user's computer) or upstream (from the user's computer to the Internet). The trend is to raise the threshold of the broadband definition as the marketplace rolls out faster services. ... [The ITU] recommendation I.113 has defined broadband as a transmission capacity that is faster than primary rate ISDN, at 1.5 to 2 Mbit/s. The FCC definition of broadband is 768 kbit/s (0.8 Mbit/s). The [OECD] has defined broadband as 256 kbit/s in at least one direction and this bit rate is the most common baseline that is marketed as "broadband" around the world. ...

+--------------- | ADSL with an analogue telephone service on the same wire is "Broadband", | ADSL on its own is NOT "Broadband", if anything it is a "Baseband" service. +---------------

Again, your definition is the revisionist one:

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... The various forms of digital subscriber line (DSL) services are broadband in the sense that digital information is sent over a high-bandwidth channel (located above the baseband voice channel on a single pair of wires).

+--------------- | The telecoms term "Broadband" has been hijacked by people who do not | know better for defining general high speed data/Internet connections. +---------------

As the latter article noted at its beginning:

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The term broadband can have different meanings in different contexts. The term's meaning has undergone substantial shifts.

and indeed it has, and continues to. *All* of the usages of "broadband" given in the latter article have been & remain valid IME [which dates back to the early 1960s]:

Broadband is always a relative term, understood according to its context. The wider the bandwidth, the greater the information-carrying capacity. In radio, for example, a very narrow-band signal will carry Morse code; a broader band will carry speech; a still broader band is required to carry music without losing the high audio frequencies required for realistic sound reproduction. A television antenna described as "broadband" may be capable of receiving a wide range of channels; while a single-frequency or Lo-VHF antenna is "narrowband" since it only receives 1 to 5 channels. In data communications a digital modem will transmit a datarate of 56 kilobits per seconds (kbit/s) over a 4 kilohertz wide telephone line (narrowband). However when that same line is converted to a standard twisted-pair wire (no telephone filters), it becomes hundreds of kilohertz wide (broadband) and can carry several megabits per second (ADSL).

Yes, that article mentions "methods where two or more signals share a medium" as being *one* usage, in the narrow field of telephony network engineering, but it has never been and is not the dominate one.


p.s. IMHO, if anyone has "hijacked" the term, it has been the recent hyping by the cellular carriers for their relatively modest data offerings... ;-}

----- Rob Warnock

627 26th Avenue San Mateo, CA 94403 (650)572-2607
Reply to
Rob Warnock

On Mon, 15 Mar 2010 21:17:30 -0500, Rob Warnock wrote: .......

Well, telephony network engineering was where I first encountered the term "Broadband" and there was a very clear understanding of what it defined.

15 (or so) years later I again encountered it when xDSL was first rolled out and it was initially used in an accurate manner when describing services that had voice as well as data on the same medium. Since then - IMHO - it has been hijacked for the various uses you have cited.

For this grumpy old ex-telco person it will remain as it was! ;-)

Come the revolution all these other whackers misusing it will be up against the wall while I chuck old handsets in their general direction......

Reply to
David Clayton

Definition of "Baseband," "Broadband," and "Carrier"

In the thread entitled "When is broadband broad enough?", our esteemed colleague in Australia, David Clayton, calls attention to the use of the term "broadband," a word that seems to appear in every news report concerning the internet and connectivity. The use of the terms "baseband," "broadband," and "carrier" have always had a contextual meaning, but more importantly, the definition seems to vary based on who is using the term and why. I am fascinated by language, and always observe word usages carefully whenever I read documents published in different eras. In my mind, the first definition of these three words is always the electrical one - but as David pointed out, not everyone shares that view.

I have here an older (1930's era) copy of the venerable text "Principles of Electricity as Applied to Telephone and Telegraph Work," published in many editions during the last century by the Long Lines Department of AT&T. The word "broadband" appears countless times throughout this edition, but even in this unassailable text it is not always used in the electrical engineering sense. In the electrical sense, "broadband" would refer to a signal the spectral energy of which occupies a broad frequency band, as the name implies. How wide this spectrum must be to qualify as broad is open to some debate, but in the case of any channelized FDM system where carriers of different frequencies are transmitted simultaneously over the same physical medium there can be no such debate - that's broadband. This remains true even if the content of the multiple carriers was originally just one channel of message content, split across multiple modulated carriers. Thus, a typical xDSL stream carrying one channel of user content, even flying solo on a "dry" copper pair, would qualify as broadband by this definition.

But here is where semantics rears it ugly head. In that same text (often referred to simply as "Principles"), a discussion of time-division multiplexing of separate message channels of low speed (telegraph) data into a single higher bitrate stream refers to this as a "broadband" service. Electrically, this stream is anything but broadband - in the case of a conventional alternate-mark encoded bitstream (as this was), the actual electrical signal would appear on an oscilliscope as square wave, albeit a somewhat phase-distorted one. If you were to send all marks and no spaces, the square wave would be quite perfect indeed - and have virtually all of its spectral energy concentrated on a very specific frequency. This, electrically, is the very definition of the narrowest of narrow bands, which is often conflated with "baseband." The use of the word "broadband" to refer to this TDM telegraph stream conforms to the definition David Clayton was discussing, i.e. carrying more than one service, or in this case multiple channels of message content.

The term "baseband" is equally subject to being defined based on context, but even allowing for that, its very meaning seems to have been construed in recent decades. Baseband, in the electrical sense, originally referred to a message signal that had not been "frequency-shifted." A good example of this would be a 1,000 hertz audio tone carried by a standard voice band telephone line. The 1,000 hertz tone playing in your ear from the telephone receiver is of course transduced directly from an electrical waveform of the very same frequency carried on the copper pair. If you were to drop the electrical signal on this copper pair into an old-style analog FDM carrier system, it would be used to modulate a higher frequency carrier wave, or, in VERY archaic language, "frequency-shifted out of the base band." (This is not to be confused with frequency-shift keying, a modulation scheme for radiotelegraph signals that is very far removed from this discussion.)

These days, however, the term baseband has come to mean something very different, particularly in relation to transport of digital message content. Its early use in digital systems applied to any encoded message stream in which the symbol rate (the true meaning of "baud") was directly correlated to the actual bitrate of the message content. Simplex telegraphy is an example of this. A more recent example would be an RS-232 connection, in which the electrical signal state in each symbol slot is directly correlated to a 1 or a 0 in the actual message bit stream. In recent decades, however, ethernet over twisted pair has become king for local area networks, and here is where markets wield their power. The various popular flavors of twisted pair ethernet all have names that contain the word "base," e.g., 100baseT. Sure enough, the "base" is short for baseband, and this misnomer, applied to twisted-pair ethernet at the beginning, has stuck. Putting aside gigabit ethernet (which splits the message data stream across more than one physical circuit), even lowly 10baseT is not actually baseband in the electrical sense. Complex voodoo encoding schemes in all versions of ethernet result in a symbol rate that is indeed lower than the actual content bit rate. Thus, the use of the word "baseband" here is strictly applicable only in the sense that David referred to, i.e., it is used to connect a single node on a network, or at least talk to only one node at a time over a given physical connection. And of course, "baseT" is what everyone in the marketplace calls it, which is all that really matters if you want to do business with everyone else.

This brings us to the word "carrier," a word which often appears in the same sentences as the words "baseband" and "broadband." This word has the hardest life of all - in addition to the electrical meaning and the number-of-channels of message content meaning, this word has yet a third job, that of defining what business a company is in. In the electrical meaning, "carrier" of course refers to a signal which is modulated by the message signal to produce a complex transmitted signal from which the message content can be demodulated at the receiving end. There are too many ways of doing this to even mention, and if you want a good lesson in carrier modulation you can ask your favorite Ham radio enthusiast to explain it. This would be a good first step, because you can't even hope to comprehend the various schemes for doing this with digital message content unless you understand the analogue signal techniques first. Too many textbooks that attempt to explain digital system modulation schemes tend to confuse encoding techniques with modulation. The two are often hoplessly intertwined, such as with QPAM, but they are indeed separate issues (and both are way beyond the scope of this article). An exploration of the encoding and modulation schemes used for modern digital content transport systems will lead the astute reader to one conclusion: These systems are such a complex amalgam of techniques developed over more than a century that it is pure folly to attempt to describe any of them using only one word. This is probably the biggest reason that these semantic debates will always be with us.

The second definition of "carrier" as it relates to the number-of-channels of message content meaning is perhaps the most common usage. Everybody is familiar with "T-carrier," the undisputed king of digital transport of voice for decades. Electrically, a true T1 is in fact a baseband signalling system, virtually identical to the multiplexed telegraph channels described above. But everyone calls it T-carrier because the single bitstream can contain as many as twenty-four separate channels of message content, in effect, "carrying" these channels. The name was applied from the very beginning, and this has always made sense, especially when one considers that it was developed as a replacement for N- and O- carrier systems, which were "carrier" systems in BOTH the electrical sense and the number-of-channels of message content sense.

The last definition of "carrier" is the business meaning - and this may be the most important of all, because without Carriers (with a capital "C"), we wouldn't be able to have this discussion. Carriers, of course, are the service providers that carry all the content that spews from our keyboards, cameras and mouths. Your phone service provider is a Carrier, as is your cable TV compnay, ISP, etc. It is from this meaning that we get the term "Carrier-grade equipment."

There is also a second, elevated class of Carriers - those who operate long-haul networks that cross continents and oceans and whose customers are in fact themselves Carriers. These Carriers never have to deal with us lowly end-user customers, instead providing transport for companies that do, making them Carrier's Carriers. This inspires the following inevitable statement: "Carrier's Carriers carry Carrier's content carefully and continuously on optical carrier." And I suspect that somewhere, on a sunny beach where one of their undersea cables meets land, there is a girl selling sea shells.

All comments to this article are welcome, even if they are to tell me I got it all wrong.

Copyright 2010 A.J. Bennett. All rights reserved. Copyright 2010 Telecom Digest. All rights reserved.

Jim Bennett

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AJB Consulting

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