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Subject:  FAQ - OTHER BROADBAND 1/31/99 Date:  1/31/1999  11:03 PM
Author:  cychiu Number:  4004 of 55215

OTHER BROADBAND - This section of the FAQ deals with all broadband issues other than xDSL specific ones, which are covered in the xDSL section.


xDSL is discussed in a different section (link) off of the Main ATHM FAQ and assumes you have read and understood this post. xDSL and cable are the two main competitors in broadband technology at the present time and there is a lot of interest in that rivalry.

Any additional questions on broadband communications or suggestions for improving this section of the FAQ can be addressed to cychiu or nole1.

The Main FAQ is available in the green area below this post.

Definition of broadband and introduction to the different types

Broadband is a technology that delivers very rapid transmission of voice, data, and video over communication networks. A simple, non-technical definition of broadband is that it carries data using an eight-lane highway, versus a two-lane country road, in the case of a standard telephone line. This means that a lot more data can be transmitted simultaneously and much more rapidly than is possible on "narrowband" media (i.e. telephone lines). The power of broadband communications lies in its ability to provide high-speed Internet access and fast transmission of information, such as video, that require a lot of stored data.

Currently, broadband communications take place across transmission media such as coaxial cable (the same that you get with cable TV and the medium that ATHM uses) or ADSL, a specialized telephone wire that allows transmissions at speeds far exceeding the traditional 56K/33.6K/28.8K/14.4K/9600/2400/1200/300 modems that most are used to.

Why does your internet connection seem to run at different speeds at different times and on different sites?

One concept that is important to understand is the idea of "shared bandwidth". When tons of people are logged onto the Internet at the same time (e.g. during the launch of John Glenn's shuttle), the entire infrastructure of the net slows down. Why? Because there is a limit to the capacity of the servers as a whole to send and receive data, although this maximum capacity is continually being expanded. In addition to the overall Internet, each site which provides content through a server has its own limitations. A good example of this is on heavy trading days, when you are (unsuccessfully) trying to connect to an online brokerage to make a trade. This explains why you sometimes get through to some sites quickly while others are bogged down. The "shared bandwidth" limitation in this instance is primarily on the server side, rather than on your browser connection, or client side.

Now about the client side of "shared bandwidth", which is more pertinent to our discussion on broadband communications. Cable access is shared among the users connected to the local cable provider. As part of the cable infrastructure, fiber optic loops are built from your local site (the connection to the Internet backbone) to different areas in your city. Each of these fiber optic lops can support a certain amount of "traffic". A simple text e-mail doesn't create a lot of traffic, but downloading a huge file or watching a streaming video that requires much more information to be transmitted over the lines uses substantially more of the capacity, thus creating more "traffic".

Each of these fiber optic loops, which typically supports anywhere from 200 to 500 users, can be described as a "shared bandwidth" loop. If all subscribers are online, watching a video on their computers, the amount of information being passed through this "pipe" is so huge that the loop bogs down noticeably. Each user sees this as an extremely slow connection. However, if you are the only one currently using the fiber optic loop, your particular connection would seem so fast that you could not tell whether or not you were online (aside from the fact that you're using IE or Netscape, of course!).


First, what is bandwidth?

short description: a measure of the amount of information that can flow through a transmission cable simultaneously (i.e. measure of data throughput)

long description: As the name implies, it is the "width of a frequency band", or, more specifically, the range of frequencies assigned to an analog channel. Let's explore this in just a little more detail. The data on your computer is stored in digital form (i.e. 1's and 0's). This data, if it is to be transmitted, however, currently needs to be carried across analog lines. We can view analog transmissions as a set of electrical waves. From elementary physics, we know waves can have different frequencies, and it turns that each frequency is capable of transmitting information. With a larger range of frequencies (i.e. a higher bandwidth), it is possible that transmit more data simultaneously (i.e. a larger data throughput).

Coaxial cable, which is familiar to most people who own cable TV, carries a
heck of a lot more bandwidth than current "twisted pair" telephone lines. The infrastructure was originally set up as a "push" technology. Cable companies were not looking for any response, but rather were "pushing" cable channels to your house in a one-way communication (similar to TV). This is why, in pre-cable modem times), you would have to call an 800 number to order pay-per-view instead of responding via your set top box. This infrastructure is being rapidly (although not rapidly enough for those of us eager to participate) upgraded to a two-way medium that will allow communication to and from your house.

As an aside: This change is very likely to bring about a complete change in the way communications take place in the next few years. The current telephone lines may be left unused as your "telephone communications" will take place through your cable line! That's one of the main reasons AT&T is buying TCI (a cable company which owns 40% of ATHM).

In any case, this upgrade will include two parts:

A backbone, which links @Home communities together. The contract for this was recently (around the start of 1999) awarded to AT&T. This initial backbone will provide for a maximum capacity of 5 million users. A picture of this backbone can be seen on the @home site:

A local infrastructure, which will allow individuals to connect to their local @Home community. See the Definition of broadband and introduction to the different types above for more of a discussion on the local cable infrastructure.


The main forms of broadband which are now starting to be deployed are coaxial cable (ATHM is a dominant player in this form) and xDSL, which stands for Digital Subscriber Line. There are also developing technologies, such as satellite and wireless, which have future potential.

A good commentary on the future of broadband cable and xDSL can be found in the Rule Breaker ATHM Buy report:
(It contains a few opinionated assertions, but gives a basic idea of the differences)

Article entitled: The last mile to the Internet

Which Bandwidth Option Is Right For You?
>From the February 1998 Issue of PC World
Nice chart of the differences in broadband technologies


Note: To get the most out of the links to messages on this board, please see the "Use the Threaded option to follow a particular subject" in the TIP -FAQ. A link to a copy of the original TIP - FAQ (that will remain good) is here, in case you haven't seen it:

Here are some links to threads on the ATHM board dealing with General Broadband Issues:

Subject: Satellites, DSL and Cable
Date: 12/6/98
Number: 1004

Subject: Bandwidth Table
Date: 12/8/98
Number: 1084

Subject: Cable vs. Satellite
Date: 12/16/98
Number: 1364

Subject: Good Overview in the Field of High Speed Service
Date: 12/16/98
Number: 1368

Subject: satellites
Date: 12/18/98
Number: 1404

Subject: Bandwidth
Date: 1/2/99
Number: 1966

Subject: Fiber Optics
Date: 1/4/99
Number: 2046

Subject: cable will defeat DSL
Date: 1/5/99
Number: 2070
Article linked to also mentions Wireless...

Subject: broadband/bandwidth
Date: 1/12/99
Number: 2567

Here are some links to threads on the ATHM board dealing with Cable Specific Broadband Issues:

Subject: Stupid Question
Date: 9/27/98
Number: 609
(Deals with connection slowing down with more users)

Subject: Product Degradation
Date: 10/1/98
Number: 623

Subject: Cable Modem Speed
Date: 12/4/98
Number: 914

Subject: Speeds and solution
Date: 12/8/98
Number: 1126

Subject: Increased customer=Decreased bandwidth
Date: 12/24/98
Number: 1546

Subject: @home access speed
Date: 1/8/99
Number: 2271

Subject: Q. on @Home Bandwidth
Date: 1/21/99
Number: 3223

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