There are a number of ways in which we can protect the data that is transmitted across wireless frequencies. When the IEEE committee formed and created the wireless 802.11 standard, they were conscious enough to know they had to take the security of wireless information into account, because wireless is in the air! Unfortunately, the committee was full of radio engineers, and as such, they really did not know about security. As a result, they made a fatal mistake when they selected the first encryption protocol to protect wireless networks. The flaws of that first protocol, Wired Equivalent Privacy (WEP), are well documented. For more information and an analysis on this, refer to http://en.wikipedia.org/wiki/Wired_Equivalent_Privacy.
In short, the selected protocol used an encryption algorithm named RC4. It uses a stream cipher, and as such, the key should not be reused. Even the author of the algorithm states this in the paper on the algorithm. Radio engineers should...