CWNP Certified Wireless Network Administrator Set 4

RF cables have upper and lower frequency range specifications. 75 and 125 ohms are the typical impedances of 802.11 WLAN connectors. Two RF connectors of the same type (e.g. SMA), manufactured by different companies, may vary in specifications. Every RF connector causes insertion loss. Large diameter RF cables cause greater loss than small diameter cables.

802.11a and 11n use six (6) "pilot" subcarriers as a reference for the receiver to detect frequency and phase shifts of the signal. ✘ 802.11a/g/n OFDM includes several combinations of modulation and coding to achieve data rates from 1 600 Mbps. ✘ With 802.11a OFDM, 16-QAM provides either 48 or 54 Mbps data rates, depending upon coding rates. ✘ 802.11ac VHT-OFDM utilizes 256-QAM, which increases the data rate significantly over 64- QAM available in HT-OFDM. ✔ In 802.11a OFDM, fifty-six (56) subcarriers are used as parallel symbol transmission paths to carry data. ✔

802.11n OFDM is more susceptible to high-power, narrowband interference than 802.11a ✘ In order to earn Wi-Fi Alliance certification, 802.11n clients stations are required to support both 2.4 and 5 GHz frequencies ✘ 802.11ac devices support the features of the VHT PHY only in the 5 GHz frequency band. ✘ 802.11ac is not backwardly compatible with 802.11n or 802.11a. ✔ When HR/DSSS devices are present, VHT MCS rates are disabled for the entire BSS. ✔

HR/DSSS (802.11b) OFDM (802.11a) ERP (802.11g) HT (802.11n) CCK (802.11b)

HT OFDM HR/DSSS ERP-PBCC DSSS-OFDM

Introduces "fast transition" roaming protocols for VoWiFi phones Better link reliability between 802.11a/b/g client devices and 802.11ac APs Improves service quality for real-time applications at greater distances Increases in receive sensitivity enhance RTLS location accuracy Stronger security with more robust encryption modes.Real 13 CWNA CWNA-106 Exam