What statement is true concerning the use of Orthogonal Frequency Division Multiplexing (OFDM) modulation method in IEEE 802.11 WLANs?
What statement is true concerning the use of Orthogonal Frequency Division Multiplexing (OFDM) modulation method in IEEE 802.11 WLANs?
OFDM was first introduced in the IEEE 802.11a amendment and has since been adopted by other PHY protocols such as ERP, HT, and VHT. These adaptations allow OFDM to be used in different frequency bands and with varied capabilities. This introduction of OFDM in 802.11a set the foundation for its use in subsequent enhancements of the standard.
http://www.rhyshaden.com/802_11a.htm OFDM is only used in 5Ghz transmissions. 802.11g ERP-OFDM, and 802.11n HT-OFDM are used in 2.4Ghz transmissions and are not specifically OFDM.
B is correct. CHAPTER 5 - PAGE 173 and 175 (Official Study Guide) 173 --> "This PHY was made available through the 802.11a amendment in 1999." 175 --> "ERP is the first OFDM-based PHY that operates in 2.4 GHz, and OFDM is the first OFDM-based PHY that operates in 5 GHz. HT and VHT, explained later in this section, are both OFDM-based as well."
Should be c
Ignore my first answer, B is right. The manual states that ERP was the first to use OFDM modulation
I think C is actually the right answer and this question is poorly worded. If they were actually wanting ERP- or HT- flavors of OFDM, I think they would have said it. I can't find any time where the 11g or 11n flavors were not specifically referred to as ERP or HT OFDM, whereas OFDM of the 11a flavor can only be described as OFDM.