Wireless Networking 2.2

802.11

IEEE 802.11n - introduced improvements to bandwith

  • can work over both 2.4 GHz and 5 GHz 

  • each band has its own radio

  • an access poin or adapter that supports 2.4 & 5 GHz operation is a “dual band” 

  • Some older Adapters only support 2.4 GHz radio

The 802.11n standard allows two adjacent 20 MHz channels to be combined into a single 4 MHz channel, refered to as “channel bonding” Due to the restricted channel layour of 2.4 GHz on a network with multiple AP’s, channel bonding is a practical option only in the 5 GHz band . However, note that 5 GHz channels are not necessarlity contagous, and the use of some channels may be blacked if the access point detects a radar signal. 

(MIMO) - multiple input multiple output

  • increases reliability and bandwidth by multiplexing signal streams from2-3 seperate antennas.

  • configuration is represented as 1×1, 2×2, 3×3 - indicates the number of transmit ans receice antennas available to the radio 

  • Nominal data rate - Theoretical maximum speed of data transfer : for 802.11n - 72 Mbps per stream/ 150 Mbps for a 40 Mhz bounded channel.

  • access points are marketed using Nxxx designations  - xxx is the nominal bandwith  

Ex- N600 2×2 acess point can allocate a bonded channel to two streams for a data rate of 300Mbps, and if it does this simultaneously on both 2.4 GHz and 5 GHz radios, the bandwidth of the access point could be described as 600 Mbps. 

  • The statement describes how the theoretical maximum speed of a dual-band Wi-Fi access point is calculated and marketed. The N600 designation represents the combined maximum bandwidth of the device's two separate radios.

  • Bonded channel - wireless channel bonding, which combines multiple Wi-Fi channels to increase bandwidth, and Ethernet channel bonding, also known as link aggregation, which combines multiple Ethernet interfaces for increased throughput and redundancy

In recent years, Wi-Fi has been renamed with simpler digit numbers; 802.11n is now Wi-Fi 4

Access points 

  • Most wireless LANs (WLAN’s) are based on the IEEE 802.11 standards (Wi-Fi)