1. 1. A cost-effective networking media for use in areas that are difficult or too costly to wire.
2. User mobility in the workplace.
2. The IEEE 802.11 WLAN standard defines the physical (PHY) layer, the medium access control (MAC) layer, and the media access control (MAC) management protocols and services.
3. Ad Hoc – Another term used to describe an independent network (Basic Service Set (BSS)).
4. Extended Service Set (ESS) – The use of multiple access points to extend user mobility.
5. Currently four physical layer technologies are being used in 802.11 wireless networking. These are direct sequence spread spectrum (DSSS), frequency hopping spread spectrum (FHSS), infrared, and orthogonal frequency division multiplexing (OFDM).
6. 802.11 DSSS implements 14 channels (each consuming 22MHz) over approximately 90MHz of RF spectrum in the 2.4GHz ISM (industrial, scientific, and medical) band.
7. In frequency hopping spread spectrum (FHSS), the transmit signal frequency changes based on a pseudorandom sequence. Pseudorandom means the sequence appears to be random but in fact does repeat, typically after some lengthy period of time. FHSS uses 79 channels (each 1MHz wide) in the ISM 2.4GHz band.
8. FHSS requires that the transmitting and receiving units know the hopping sequence (the order of frequency changes) so that a communication link can be established and synchronized.
9. The 802.11a equipment operates in the 5GHz range. The modulation technique used is Orthogonal Frequency Division Multiplexing (OFDM)
10. a. 802.11b - 11 Mbps
b. 802.11a - 54 Mbps
c. 802.11g - 54 Mbps
d. 802.11n - 200+ Mbps
11. Multiple Input Multiple Output (MIMO) uses a technique called space-division multiplexing, where the data stream is split into multiple parts called spatial streams. The different spatial streams are transmitted using separate antennas. With MIMO, doubling the spatial streams doubles the effective data rate.
12. 802.11n only...