1) They’re both regulatory agencies (FCC is US; ITU-R is international); and 2) They regulate communication frequencies.
How are FHSS and DSSS different?
FHSS “hops” frequencies and is no longer used; DSSS doesn’t hop frequencies – rather, it sends data across every frequency… further, its still in use today.
What are the differences between 802.11a and g?
A is faster, but has a much smaller area of coverage and only works in the 5ghz frequency.
What is the difference between channel bonding and dual band?
Channel Bonding – 802.11n – combines two adjacent 20hz channels to form a 40hz channel for greater bandwidth. Note, that without channel bonding, a typical channel will only have 20hz of bandwidth for throughput. Conversely, “dual band” describes a wireless access point’s ability to transmit data in both the 2.4ghz and 5.0ghz range. This results in a device that can transmit data between devices (if they're configured this way) on whichever frequency is “best” at any given moment… also, “dual band” makes it possible to have older wireless devices running in your network through the same access point.
When should you implement a dual band access point?
When you have older devices on your network that cannot transmit in both 2.4 and 5.0ghz.
What improvements are included with 802.11n standards that improve speed and distance?
a. MIMO, Channel Bonding and Frame Composition
2.4 GHz Spectrum
Eleven total channels (11).
Three (3) “non-overlapping channels” available for transmission of data.
Many devices operate on this frequency (e.g., WiFi access points, microwave ovens, cordless phones, Bluetooth devices, and more).
The more crowded the frequency, the higher the risk of interference and degraded performance.
5.0 GHz Spectrum
Twenty three (23) total channels.
Twelve (12) “non-overlapping channels” available for transmission of data.
(8X more than 2.4 GHz)
Less crowded than the 2.4 GHz spectrum.
802.11a
Frequency: 5 GHz
Max Speed: 54 Mbps
Max Range: 150 Ft.
Backwards Compatibility: N/A
802.11b
Frequency: 2.4 GHz
Max Speed: 11 Mbps
Max Range: 300 Ft.
Backwards Compatibility: No (not with a)
802.11g
Frequency: 2.4 GHz
Max Speed: 54 Mbps
Max Range: 300 Ft.
Backwards Compatibility: With 802.11b
802.11n (vid)
Frequency: 2.4 GHz or 5 GHz
Max Speed: 600 Mbps
Max Range: 1200ft
Backwards Compatibility: With 802.11a/b/g, depending on implementation
802.11ac
Frequency: 5 GHz (for ac speeds… falls back to 802.11n and below for compatibility)
Max Speed: 1.3 Gbps
Max Range: 1200ft
Backwards Compatibility: With 802.11a/b/g, depending on implementation
Compatibility (frequencies)
B compatible with G (both 2.4 GHz)
N (5.0 and 2.4 GHz) compatible with A, B, G
AC compatible with A, B, G & N
Potential Performance Issues:
Building Materials
Physical Placement of AP
Crowded or Noisy Frequency
How does 802.11xyz Wi-Fi work?
Adhoc Networks
Components
Two or more wireless devices, communicating with each other in a peer-to-peer fashion
Uses a physical mesh topology.
Is cheap and easy to set up.
Cannot handle more than four hosts.
Requires special modifications to reach wired networks
An access point (AP), sometimes called a wireless access point, is the device that coordinates all communications between wireless devices as well as the connection to the wired network. It acts as a hub on the wireless side and a
