NETGEAR CG814M manual Wireless Channel Selection

Reference Manual for the Model CG814M Wireless Cable Modem Gateway

The 128-bit WEP data encryption method consists of 104 user-configurable bits. Similar to the forty-bit WEP data encryption method, the remaining 24 bits are factory set and not user configurable. Some vendors allow passphrases to be entered instead of the cryptic hexadecimal characters to ease encryption key entry.

Wireless Channel Selection

IEEE 802.11b wireless nodes communicate with each other using radio frequency signals in the ISM (Industrial, Scientific, and Medical) band between 2.4Ghz and 2.5Ghz. Neighboring channels are 5Mhz apart. However, due to spread spectrum effect of the signals, a node sending signals using a particular channel will utilize frequency spectrum 12.5Mhz above and below the center channel frequency. As a result, two separate wireless networks using neighboring channels (for example, channel 1 and channel 2) in the same general vicinity will interfere with each other. Applying two channels that allow the maximum channel separation will decrease the amount of channel cross-talk, and provide a noticeable performance increase over networks with minimal channel separation.

The radio frequency channels used are listed in Table B-1:

Table B-1.	802.11b Radio Frequency Channels
Channel	Center Frequency	Frequency Spread
1	2412Mhz	2399.5Mhz - 2424.5Mhz
2	2417Mhz	2404.5Mhz - 2429.5Mhz
3	2422Mhz	2409.5Mhz - 2434.5Mhz
4	2427Mhz	2414.5Mhz - 2439.5Mhz
5	2432Mhz	2419.5Mhz - 2444.5Mhz
6	2437Mhz	2424.5Mhz - 2449.5Mhz
7	2442Mhz	2429.5Mhz - 2454.5Mhz
8	2447Mhz	2434.5Mhz - 2459.5Mhz
9	2452Mhz	2439.5Mhz - 2464.5Mhz
10	2457Mhz	2444.5Mhz - 2469.5Mhz
11	2462Mhz	2449.5Mhz - 2474.5Mhz
12	2467Mhz	2454.5Mhz - 2479.5Mhz
13	2472Mhz	2459.5Mhz - 2484.5Mhz

B-14 Networks, Routing, and Firewall Basics