Making Things Talk

178 MAKING THINGS TALK

Why Isn’t Everything Wireless?

The advantage of wireless communication seems obvious at first: no wires! This makes

physical design much simpler for any project where the devices have to move and

talk to each other. Wearable sensor systems, digital musical instruments, and remote

control vehicles are all simplified physically by wireless communication. However, there

are some limits to wireless communication that you should consider before going wireless.

Wireless communication is never as reliable

as wired communication

You have less control over the sources of interference.

You can insulate and shield a wire carrying data com-

munications, but you can never totally isolate a radio or

infrared wireless link. There will always be some form of

interference, so you must make sure that all the devices

in your system know what to do if they get a garbled

message, or no message at all, from their counterparts.

Wireless communication is never just

one-to-one communication

The radio and infrared devices mentioned here

broadcast their signals for all to hear. Sometimes that

means they interfere with the communication between

other devices. For example, Bluetooth, most Wi-Fi radios

(802.11b, g, and n) and ZigBee (802.15.4) radios all work

in the same frequency range, 2.4 gigahertz. They’re

designed to not cause each other undue interference,

but if you have a large