Here is a direct quote from “Why such slow Wi-Fi?” in a recent Los Angeles Times

Question

Here is a direct quote from “Why such slow Wi-Fi?” in a recent Los Angeles Times article:
“In an analysis of fixed broadband and mobile speeds in July, Speedtest ranked the United State No. 9 for broadband and No. 46 for mobile (Nos.1, respectively, Singapore and Norway. Last: Venezuela and Iraq).
Part of the issue for Americans: Many of us still have home service based on copper wire, not fiber.

Craig Ganssle, chief executive of Camp3, which works on wireless infrastructures, explains this difference: Copper service is based on the speed of sound (generally about 1,125 feet per second if it’s 68 degrees and the air is dry), and fiber is based on the speed of light (about 984 million feet per second).

With a few exceptions, most of us get our home Internet access through a cable modem or a DSL modem, and the wires that connect our modems to our ISPs are made of copper. Let’s assume you are streaming a Netflix movie. The nearest Open Connect appliance, which Netflix uses to host and deliver movies to customers (see Chapter 1, pg. 7-8), is 3 miles from your home. Let’s also assume you have already found the movie to watch and is ready to start. You click on the Play button, a one-bit signal is sent over the 3-mile copper wire to reach the Open Connect appliance, which then starts sending the digitized movie frames back to your home, also over the 3-mile copper wire.

Questions:
a. Given the quoted speeds above (i.e., 1,125 feet per second vs. 984 million feet per second), from the moment you click the Play button, to the moment the first bit of the movie appears on your screen, how long will it take (round-trip time) over a copper wire? Over a fiber optic cable?

Note: 1 mile = 5,280 feet

b. How does your calculated result over a copper wire compare to your own experience of streaming movies on the Internet?

What is your conclusion?

Explanation / Answer

Given the distance of Open Connect appliance: 3 miles = 15840 feet

the round trip distance = 15840 x 2 = 31680

a)

The speed of copper wire = 1125 feet per second

time = distance / speed

so the time taken using copper wire = 31680 / 1125 = 28.16 seconds

The speed of fibre optic cable = 984 million feet per second = 984 feet per microsecod

(1 second = 106 microseconds)

so the time taken using fibre opric cable = 31680/984 = 32.19 miroseconds or 0.00003219 seconds

Note: The calculations have been done without taking any atmospheric change or external interference into consideration.

b)

Copper wire have less speed as the speed in them is effected by several factors. These wire uses old technology to transfer data bits and so are slow. But i believe the dsl connection that i have at my home is still a bit faster than this calculated result.

Still, fibre optic cable are an improved medium and can transfer data at an unbelivably fast rate. But they are expensive accordingly. An optimised system may use both types of cable to balance speed and expenses.

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