Frequency Planning and Adjacent Channel Interference in a DSSS Wireless Local Area Network (WLAN)

The new communications standard for wireless local networks is the IEEE 802.11 standard. 802.11b specifies that we use the ISM band at 2.4GHz. The ISM band at this frequency is 83MHz wide. For North America, under FCC regulations, the 83MHz of bandwidth is divided into 11 channels. Every channel has a frequency bandwidth of 22 MHz [1]. In North America, channels 1 through 11 are used and only Ch1, Ch6, and Ch11 physically do not have any overlapping frequency ranges. Therefore, it follows that frequency planning has been done using only these three channels. This greatly reduces the capacity and utilization of a given Wireless LAN.