The 802.11n amendment allows for up to 4x4 MIMO. That's 4 transmitters and 4 receivers working at the same time. Due to cost, nobody is building a 4x4 system. Instead, we're seeing 2x2 on the cheap stuff, 2x3 on the higher-end client radios and the lower-end APs, and 3x3 on the higher-end APs. More transmitters and receivers means better quality: better reception, higher throughput, the works. Always look for 2x3 stations and 3x3 APs whenever possible. Continue reading...
Earlier this year Nokia released an updated version of their popular Nokia N770 Internet Tablet. The N800 excels at being a small, light-weight device capable of WiFi as well as Bluetooth access to the Internet. THis is a user-based review of this great little device.
In my daily foraging for goodies in the 802.11 standard, I tripped across what seemed to be something routine, but upon deeper inspection (the reading of several RFCs), it seems that PAP, CHAP, and MS-CHAP cannot be used between an authenticator and authentication server in an RSN.
When will the madness end? With 802.11n, we have a newly elongated frame format.
Frame Control: 2 octets
Duration/ID: 2 octets
Address 1: 6 octets
Address 2: 6 octets
Address 3: 6 octets
Sequence Control: 2 octets
Address 4: 6 octets
QoS Control: 2 octets
HT Control: 4 octets (new!)
Frame Body: 0-7955 octets (yeah baby!)
FCS: 4 octets Continue reading...
802.11n has many new features including Space Time Block Coding (STBC), Spatial Multiplexing (SM), Cyclic-Delay Diversity (CDD), Maximal Ratio Combining (MRC), and Transmit Beam Forming (TxBF). A great summary of these features is found in an Atheros whitepaper here: http://www.atheros.com/pt/whitepapers/MIMO_Pwr3_whitepaper.pdfContinue reading...