INTERNET CONNECTION OPTIONS
IN SUN CITY TX:

HIGH-SPEED INTERNET ACCESS

Peter Roll
July 22, 2002

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I. Introduction 

Woe unto you for asking a former physics teacher to speak on this subject!

Modes of high-speed access to be discussed:

• telephone modem (for comparison)
• Digital Subscriber Line (DSL) -- based on telephone technology
• cable modem service -- based on cable television technology
• wireless -- based on cell phone technology based (spread-spectrum radio)
• satellite service (a niche for areas where other services not available or competitive; lower performance) -- not going to discuss this further because not competitive in Georgetown.

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Table of Contents

Modem -- what does the word mean?

Telephone modem

Digital Subscriber Line (DSL -- a service provided through telcos):
Cable modem service (cable TV companies):
Wireless -- radio (local providers -- the little guys)
Costs
Advertising claims
Some comparisons
The bottom line in Sun City
What speeds do you really get with these services? How do you determine speed?

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II. Modem -- what does this word mean?

An abbreviation for "modulator-demodulator"

• digital data always transported on an electromagnetic "carrier" signal (a high-freq. oscillating electrical voltage)
• "modulation" = imposing variations on the carrier signal to represent the 1's and 0's of computer data
• "demodulation" = the reverse process of extracting the 1/s and 0/s from the carrier wave and converting them back to digital data bits for use by a computer
• the four modes of high-speed access use 
• different kinds of carrier signals; 
• different mod/demod processes; and
• different kinds of wire (including no wire at all -- radio)
  

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III. Telephone modem

• voice frequencies, 3-5,000 electr. voltage vibrations/sec, or 3-5 KHz
• audio carrier signal, very fancy modulation techniques to cram 40-50 Kbits/sec into 3-5 KHz -- nearly 10 bits per Hertz
• still slow for a lot of stuff today
• won't work at  full speed in many locations, incl. some in Sun City

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IV. DSL
-- a service provided through telcos

DSL = Digital Subscriber Loop or Line

Sophisticated mathematical modulation techniques used transmit very high bandwidths over telco wires and get data rates up to 9 Mb/sec downstream and 1.5 Mb/sec upstream-- while still carrying an analog voice telephone signal in the lowest, audio-frequency range. 


Differring xDSL services with different data rates:

• ADSL (assymetric; upstream rate low, downstream rate high; common consumer service)
• SDSL (symmetric, upstream and downstream rates the same)
• HDSL (high data-rate DSL)
• VDSL (very high-speeed DSL)
• etc. etc.
  

Common consumer service:  ADSL at speeds of (Verizon):

• 768 Kbits/sec downstream or download (e.g., viewing web pages, downloading software)
• 128 Kbits/sec upstream or upload (e.g., sending keystrokes, e-mail and attachments, etc.)

Schematic diagrams  of DSL services and home connections:

(a) DSL service through telephone company equipment to the Internet, using a DSLAM (DSL Access Multiplexor)

(b) Connecting home equipment to DSL: a single computer




(c) Connecting home equipment to DSL: a multiple computers on a network

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V. Cable modem service (cable TV companies)

TV signals occupy 6 MHz channels, over the air or on a coaxial cable.

A typical CTV coax cable supports 400 MHz --
ergo, 130 TV channels.

TV coax bandwidth is split into

• 6 low-freq. channels for upstream transmissions;
• 120 or so high-freq. channels for downstream transmissions (TV programs, where all the money is);

• simple, cheap  devices called directional couplers enable splittinig the frequencies carried by the cable in this way
• called a low-split system; mid-split and high-split are possible with more upstream channels, but CTV operators can't make money that way....

Schematic diagrams  of cable modem services and home connections:

(a)  Diagrams of cable modem service from the home through the cable television head-end to the Internet:   



(b) Connecting home equipment to a cable modem system: a single computer



(c) Connecting home equipment to a cable modem sysetem: multiple computers on a home  network

 

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VI. Wireless -- radio (local providers -- the little guys)

IEEE  802.11b standard for low-power, unlicensed spread-spectrum wireless data transmission:
wireless Ethernet (10 Mbits/sec)

• short-range (300-1,500 ft)

The basic spread-spectrum technique:

• freq. jumps around randomly inside a given band of very high frequencies (2.4 GHz or 2.4 billion cycles of vibr./sec) -- same frequency range as cellular telephones
• a way of avoiding interference and getting much more info into a given freq. range
• a way of making it difficult to intercept the communication
• invented and patented by Hungarian movie actress Hedy Lamaar in 1940!!
• used for secret communications by US Govt. from WWII through 1970's
• the technological basis of cellular telephone service
• more recently, an unlicensed portion of radio spectrum at 2.4 GHz set aside for low-power wireless data -- now used by the 802.11b standard for 11 Mbits/sec communication over 400-ft ranges (within an office complex).

Adapted for use over longer distances, initially by amateurs:

• directional antennas for both transmitting and receiving -- coffee cans on up !
• distances up to 20 miles achievable with no line-of-sight obstructions
• but it's tricky and requires seat-of-pants engineering for each location; ergo, 
• attractive to amateurs: Dave Hughes in the Colorado Springs area has become an internationally-recognized exponent and activist for wireless and other cheap, non-commercial home remedies over the past 15-20 years.  
• unattractive for general, mass commercial uses
• used and economical in special circumstances where other high-speed services not available
• the "white-box" approach to high-speed Internet access (small, local entrepreneurs) 

Schematic diagram of a wireless Internet access service:

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VII. Costs

A. DSL service in Sun City:  Verizon
     
Standard home service:

• Dynamic IP address
• 128 Kb/sec upstream, 768 Kb/sec downstream
• $49.95/month
• No activation fee
• Special offer through 7/31/02: 1st month free, 2nd and 3rd months $29.95,
• $125 charge for DSL modem if not returned after service cancellation within 12 months.
• Must have Verizon telephone service in home.
• Self-installation kit
• Up to 4 e-mail accounts
• 10 MB of personal web space

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B, Cable modem service in Sun City: Cox-Internet

• Dynamic IP address
• Cox Express Lite (128 Kb/sec up, 128 Kb/sec down):  $34.95/month;
• Cox Express  (128 Kb/sec up, 1024 Kb/sec down):    $44.95/month;
• deduct $10/mo if you buy your own cable modem ($60 at Cox office, or comparable at big-box stores)
• Cable modem rental is included in monthly service fees. Prices exclude applicable taxes and franchise fees. Prices subject to change. Offer available to residential customers only. Service available in limited areas. Some restrictions apply. $24.95 Activation Fee for Cable Modem Accounts.  Dynamic IP Addresses only. Basic Cable is required to receive Cox Express services. 10 Base-T Ethernet network card required for Cox Express connection. No Risk Money-Back Guarantee within 14 days of installation."
• Two e-mail accounts on request (more for a fee);
• Personal web space (I think you may get 2 or 5 MB on request; it's $12.95/mo for 10 MB -- discuss this with them if this is important to you).

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C. Wireless service near Sun City:  Internet Gateway

Keith Stolle is working on it -- has a few commercial wireless users in selected locations in nearer-in to Georgetown.

Internet Gateway home wireless accounts:

• 256kb (1-2 users) monthly ($79.00)
• Setup fee depends on circumstances
• No other services are needed to qualify

Wireless service is not yet feasible in Sun City, but it's close.

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VIII. Advertising claims

Advertising hype -- attack ads by SBC favoring DSL:

• initial ads completely misleading about loading of cable modem service
• current ads about neighbor kids invading your house are just dumb.

Basis for ads:  Local loop bandwidth is shared within a neighborhood by cable modem services; not shared in DSL services.  See diagrams for cable modem and DSL services.

Does this sharing degrade the speed and quality of cable modem service?

• Yes, if the operator puts too many customers on the same local loop
• No, if the operator manages bandwidth and loads properly.

Bandwidth management to maintain customer speed is necessary on all kinds of Internet access services -- telephone modem systems service AOL have been notoriously badly-managed in the past !  Local bandwidth sharing in a cable modem system is just one of several components of capcity to manage.  

How does Cox-Internet manage its local-loop bandwidth?  

• 500 customers per loop -- then add more loops (we have been told....);
• they increased data speed/capacity of local loop from 8 Mbits/sec to 32 Mbits/sec last year;
• we have experienced no slowdowns so far in Sun City.

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IX.  Some service comparisons -- DSL and Cable

Both Cable modem and DSL services have significant local startup problems when a company first begins offering them, because the local service personnel are experts in telephone or television systems, not data systems.

Cable modem systems nationwide are about 9 months ahead of DSL in maturity and stability of service.

Cable modem system have a much larger market share nationwide (and locally) because of this head start. 

Local Exchange Carrier telcos (LEC's -- the owners of the local infrastruture) have been under some pressures to open their lines for DSL services by 3rd parties -- where this has been done, the market has grown much faster than where it has not been done.

Many LECs have been able to limit or prevent 3rd-party DSL consumer services by pricing of access to their infrastructure (true locally).

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X. The bottom line in Sun City

Both cable modem and DSL consumer services are available.

Why is 768Kb/sec (DSL) the same as 1024 Kb/sec (cable)?  Because the speed you actually get from any web (or file transfer) site depends more on the speed with which the server operates than the speed of your Internet connection (see discussion of speeds in the final section).

They both give provide equivalent speeds and levels of service

There is no obvious reason to select the higher-priced service unless you have a special reason or need which it satisfies.

Some possible special reasons for DSL:

• don't want to subscribe to basic cable TV service (in which case the price advantage disappears or reverses a little);
• need a static (fixed) IP address to operate w web server from home, or for a business (can get business accounts from both Verizon and Cox for this, but you will have to check the comparative pricing yourself);
• worked for the telephone company all your life, hold a lot of their stock, and want to support their business.
• there are surely others ... 

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XI.  What speeds do you really get with these services? How do you determine speed?

The speed with which a server can dish out information to your computer is usually the factor that controls the speed you see on your Internet connection, not . 

What are the important factors -- other than the speed of the local connection itself -- that can slow down the speed with which you receive info from an Internet server?

• a slow server computer
• a lot of users hitting the server at the same time you are -- exceeding the capacity of the server;
• -everal of the servers in a server farm out of service when you and a lot of others are trying to get info;
• congestion or a link down on the Internet between you and the server.

These factors are outside of your control and outside of your ISPs control. The connection will be just as slow regardless of how fast your local Internet connection is. 

Q: There are many Internet sites that claim to measure the speed of your Internet connectiion.  Are they reliable?

A: In my experience, they are not -- you can't rely on them unlesss you know a LOT about how they work.  Most of the time, I have found these measurements to contradict my own method of estimating local connection speeds. 

Q: How do you do it?  And why do you trust your estimates better than those of these big companies who obviously know more about the Internet than you do?

A: These speed-measurement web sites certainly should know a lot more about the details of how the Internet is functioning today than I do, and I assume they do.  Their principle objective, however, is to make more money by getting more people to hit their web site.  Here's how I make my estimates:

• do a lot of file downloading -- software updates, new programs, photos, movies, etc -- fairly large files (1 MByte or more), and do it a few times a week;
• use Internet Explorer or Netscape to do the file downloading -- both will give you a running record of the average speed of the download, in KBytes/sec or MBytes/sec;
• keep track of these numbers each time you do it -- either write them down or make a mental record so that you become familiar with the numbers;
• check the running tallies of the download speed by measuring the total time for the download with your wristwatch and the time into the file size in MBytes or KBytes -- make sure the running tallies are in the  same ballpark with this calculation;
• you will note that these speeds varyy all over the map, depending on time of day and the site from which you are downloading; and they will vary for the same site from time to time and day to day;
• the max. speed of your local connection cannot vary this much -- particularly when you do it in the middle of the night when you know your neighbors are all asleep;
• the numbers give you a sense of the variation in download speeds of the Internet and its servers as a whole;
• the maximum numbers you  get give you a valid estimate of the speed at which your local connection will operate when it is fed with a stream of data as fast as it can handle -- this is the number you should compare with what your ISP tells you about speed; i.e.,
• Cox says 1024 Kbits/sec: a KByte is 8 Kbits plus some overhead, so you might expect a max. speed, estimated this way, of 125 KBytes/sec
• Verizon says 768 Kbits/sec, so you might expect a max. speed estimated this way to be 96 KBytes/sec.

An example as further evidence:

My son in Minneapolis has cable modem service from AT&T (aka MediaOne aka TCI from recent acquisitions and mergers).  AT&T does NOT limit its service to subscribers to 1024 Kbits/sec -- they will let a subscriber have the whole bandwidth of a 6-MHz TV channel. (This is not really a desirable feature -- it's an example of weaker management of local bandwidth than we see here from Cox!)  As a reeult, when I clock downloads in Minneapolis, I get speeds of up to 200 Kbits/sec!  Here in Sun City, the highest I've ever seen is 120 or 122 Kbits/sec -- pretty close to the rated speed for Cox's service.

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