Wireless Access Points and RF Basics
What this domain covers
Wireless fundamentals start with RF: frequency bands (2.4 GHz and 5 GHz, plus 6 GHz in Wi-Fi 6E), channels, channel width, and interference. Know that 2.4 GHz has fewer non-overlapping channels (1, 6, 11 in North America) and better range but more interference; 5 GHz has more channels and higher throughput but shorter range. Understand SSIDs, BSSIDs (AP radio MAC), and how clients associate. Learn the 802.11 standards progression (a/b/g/n/ac/ax) and key features like MIMO, MU-MIMO, and OFDMA. Understand transmit power, RSSI, SNR, and how cell sizing and channel reuse affect roaming. Know basic security handshakes (WPA2/WPA3, PSK vs 802.1X) at a conceptual level.
Traps to watch
Questions confuse channel width with channel number, or assume wider channels are always better - wider channels mean fewer non-overlapping channels and more co-channel interference. Another trap: assuming higher transmit power always improves the network; it can create sticky clients and co-channel interference. Remember that SNR (signal-to-noise ratio) matters more than raw signal strength.
Worked example / rule of thumb
Rule of thumb: plan channels to avoid overlap; size cells for coverage, not max power. Example: in 2.4 GHz, use channels 1, 6, and 11 only. In 5 GHz, prefer 20 or 40 MHz widths in dense areas to preserve channel reuse. Aim for adequate SNR (commonly ≥25 dB for good performance) rather than simply maximizing RSSI.