802.11a amendment. Understand that MIMO systems may use HT-OFDM and can operate
in either the 2.4 GHz ISM band or the 5 GHz UNII band.
Understand the difference between CSMA/CD and CSMA/CA. Know the differences
between access methods and that they can either detect or attempt to avoid collisions. Also
understand that IEEE 802.11 wireless networks use distributed coordination function
(DCF) mode as a contention method to send data.
Know the differences among various physical layer wireless technologies, such as FHSS, DSSS, HR/DSSS, OFDM, ERP-OFDM, and MIMO. The uses of physical layer technolo-
gies vary depending on radio frequency, applications, and desired data rates. Understand
the standard or amendment each physical layer technology uses as well as advantages and
disadvantages of each, including co-location and interference.
Understand that co-location of WPAN and WLAN devices may cause interference and affect performance. WPAN and WLAN devices might be co-located in the same RF
space. Know the potential impact of co-location on performance and other factors. Some
WPAN and WLAN devices use the same frequency and spread spectrum technology.
Understand that this can cause interference.
Key Terms
Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA)
Carrier Sense Multiple Access/Collision Detection (CSMA/CD)
channel
channel planning
co-location
contention
direct-sequence spread spectrum (DSSS)
distributed coordinated function (DCF)
Extended Rate Physical Orthogonal Frequency Division Multiplexing (ERP-OFDM)
frequency-hopping spread spectrum (FHSS)
high rate/direct-sequence spread spectrum (HR/DSSS)
interference
multiple input/multiple output (MIMO)
narrowband communication
network access methods
orthogonal frequency division multiplexing (OFDM)
single input/single output (SISO)
spatial multiplexing (SM)
spread spectrum
spreading code
subcarrier
Review Questions 153Review Questions
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