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Comparison between the inner workings of physical layers for 802.11b and 802.11a standards.


Today’s article is all about the comparison in between the 802.11.b and 802.11a. I will introduce some ideas about the multiplexing used and error scheme applied.

802.11b and 802.11a both were introduced in the 1999. Although, MAC layer for both standards are same, the differences are confined in the physical layer. 802.11b has lower speed starting at 2 MBPS to maximum operates at 11 MBPS whereas 802.11a has the higher speed of maximum 54 MBPS due to use of orthogonal frequency division multiplexing (OFDM) and forward error correction (FEC) scheme over DSSS (spread- spectrum) used by 802.11b.(guide to wireless communication, 4th edition) Moreover, 802.11b network offer 11 channels but provides only 3 non-overlapping channels (1,6,11) however 802.11a have 8 non-overlapping channel that reduces interference increasing the throughput. 802.11a operates at 5 GHz frequency band whereas 802.11b operates only at 2.4 GHz. 802.11a is not backward compatibles whereas 802.11b is backward compatible, so 802.11a is not compatible with 802.11b. Also, due to high carrier frequency the effective overall range of the 802.11a is less compared to 802.11b (Wikipedia)

  •      Explain how 802.11i allows for a client device to be authenticated against an authentication server.

today we discussed about the comparison between the inner working of physical layer, now we will learn authentication methods applied in the 802.11i for the client in the server. Without much delay, the discussion can be found on as:

802.11i is the grouping of various security functions to protect the WLAN data frames by providing mutual authentication between wireless devices and access points, controlled access to network and security keys management. In 802.11i, an external authentications server- like Remote Authentication Dial-In User Service (RADIUS) is used to authenticate the client devices on the network. RADIUS is a popular method to authenticate the user in network, before the association with an Access point (AP). (Guide to wireless communication, 4th edition) 

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