>>Broadband. <<
From lowest to highest, the transmission speed ranges are characterized by
narrowband... wideband... broadband... broadband SONET... pure optical
In the wireless realm, there are additional characterizations, but let's stick to wireline, cable, terrestrial, where most of the abuse of the language takes place.
Today, the term "broadband" itself is at best a misnomer when applied to cable modems and twice-fold when it is used to describe DSL plumbing. Cable modems and DSLs may attach to line facilities that are attached upstream to broadband facilities, but CMs and DSLs themselves do not operate at broadband speeds. Not a one of them.
The term broadband is a convenient prop used for hyping a service that is merely a little better than narrow band, or yesterday's wideband, at best. It's all relative to where we employ these terms on the time line.
In the late Sixties, broadband data was achieved by sending frequency shift keyed, or manchester encoded radio frequencies over coaxial facilities on the order, typically, of 48 kb/s, sometimes 50 kb/s.
Only the most affluent businesses and municipal services used them. They were expensive, and required the most awkward set of provisioning techniques you could ever imagine to get them established. We're talking about amplifiers (repeaters) on pole tops, in person holes (hey! I try to do the right thing here), work boxes, and in building easements. And coax was not ubiquitous, by any menas, in the telco's outside plant, which meant that often times a wideband or broadband link had to be pulled from scratch. As opposed to cross connecting existing twisted pairs on main frames which were tied together by cables between central offices.
When T1 facilities were used in that era for higher speed data delivery, they would butcher the basic T1 scheme with some god-forsaken modulation contraption on the front end, and only managed to derive 200 kb/s out of them through over-sampling techniques. This, even though the baseband signal of T1 was actually capable of 1.544 Mb/s.
In those days and into the mid Seventies, broadband was considered anything in the region of 200 kb/s to 500 kb/s, and occasionally above.
Then T1 Digital Data Services, or DDS, was inaugurated in 1976, and things took an incremental leap upwards. Now digital lines were available at 2.4 kb/s, 4.8 kb/s, 9.6 kb/s, [19.2 kb/s], 56 kb/s, [64 kb/s], and 1.536 Mb/s.
Pushing into the mid-Eighties, with the proliferation of privatized T1s and T1 multiplexers, the 50 kb/s and 64 kb/s speeds were pushed down in rank to "narrowband." With the added popularity of DDS operating at 56 kb/s achieving ubiquitous coverage, over time, this trend was enhanced further.
The 200 kb/s through real T1 speeds of 1.5 Mb/s were suddenly considered wideband, not broadband, and broadband was a future that would be in the range of super-T1, into the T3 range (44.746 Mb/s) and beyond.
Modems and line drivers themselves were not abundant at those data rates, and those that did exist were ultra expensive, and didn't scale well, since the didn't operate fast enough to keep up with the newer fiber-enabled transmission media.
For example, suddenly there were optical transmission systems capable of supporting 139 Mb/s (3 T3s) , 274 Mb/s (6 T3s or a T4) and 560 Mb/s (2 T4s or a T5, although this was never officially a sanctioned rate by the ITU) and beyond upwards into the 1.8 Gb/s region. Those constraints didn't last long, for SONET was right around the corner.
Soon, data devices operating at the T3 speed and above would prove to be both technologically viable and economically affordable for commercial use.
In the Early Nineties, everything below T1 was shifted downward in stature to narrowband, T1 through T3 was [and to a great extent, still is) considered wideband, and super-T3 speeds were elevated to the status of Broadband.
Some vendors now differentiate between Broadband and SONET Broadband, alternately distinguishing themselves by various gimmicks in name only.since there isn't any broad consensus as to the meanings of these ranges anymore.
[[In the Late Nineties, going into the next millennium, broadband has taken on meanings that are actually meaningless when applied to Internet access where the everyday user is concerned. ]]
But if we followed the established progression scheme that preceded this period, narrowband at this point would be everything up through several T1s, wideband would be fractional T3 through OC-3 (155 Mb/s) and broadband would be everything from OC-3 up through OC-192 (10 Gb/s), and climbing.
Transcendent bands in the pure optical domain, those poised to characterize speeds beyond broadband, and soon to be called broadband themselves before long, are those channel widths found in wavelengths (lambdas), capable of supporting multi-gigabits up through the Terabit range, and beyond.
And yet, the trade rags and neophytes alike would have those who are struggling their way through a shared 10 Mb/s during peak periods of use, thinking that they've bought a ticket on the broadband express.... when, in reality, they're lucky to be getting a fraction of a T1 or slightly over a T1 in the process, at best, more often than not. That's not broadband, that's the lower limit of wideband.
And DSL subscribers... they too claim that they are pushing broadband speeds in their glossies, when they are only doing 680 kb/s down and 128 kb/s up, typically. That's not even fully wideband, rather it approaches the realm of narrowband.
The terms used to describe these transmission ranges have been misused so much, so badly, that they are only meaningful to those who use them incorrectly.
And so it goes... |
