Speed Limits on the Cyberhighway
It's true: After you finish a day of driving on our nation's actual streets and
highways -- wisely restricted by various speed limits -- you'll be facing simi-
lar limits on the cyberhighway. Unlike federal, state, and local authorities,
however, the people in charge of the cyberhighway are constantly searching
for ways to let us go faster.
What limits speed on the cyberhighway is the performance limit of internal
protocols and the wireless environment. So here's a look at a few things that
limit speed -- and a way to put it all into perspective: comparing real-world
speeds with typical Internet-connection speeds.
Measuring speeds in cyberspace
You can measure your speed on the highway by looking at a speedometer
indexed in miles per hour, kilometers per hour, or (sometimes) both.
Traveling at sixty miles per hour means you're covering a distance of 1,056
inches every second -- and, because you can easily tell an inch from a mile,
this measurement has meaning.
Data-transmission rates are commonly measured in bits per second (bps). So
what's a bit? It's both symbolic and real: In mathematical terms, it's either a 1
or a 0; in electrical terms, it's a state of being (respectively) either on or off.
By its lonesome, a bit is pretty insignificant -- but if you put eight bits
together in a string, you get a byte -- and then there are 256 possible combi-
nations of ones and zeros. That's enough to represent all the individual let-
ters, numbers, spaces, and symbols necessary for communication.
It takes 32 bits of data (that is, 4 bytes), to represent a number such as 5828,
the number on the front of my house. If you wanted me to put a comma
between the 5 and the first 8, however, it would take eight more bits --
another byte -- and I'd have to head for the hardware store to look for
a copper comma.
Now, the 802.11b standard specifies a data-transmission rate of 11 Mbps --
and the M represents mega (a million). 11 Mbps, then, means data can be
transmitted at a rate of eleven million bits per second. If you put that in terms
of inches per second, that'd be like traveling down the highway at a speed of
625,000 miles per hour. (Oh yeah, that'd be a ticket.)
Part I: The Wonderful World of Wireless Fidelity
Page 24
