Friday, March 5, 2010

The Week

Monday (or Tuesday?) me, Henry and Louie moved the back row of computers to the front and vice versa since Mr. Elkner wanted to be able to scribble stuff on the smartboard and the people working on the Google App Engine can see it.

Tuesday I stayed after school with Henry to check on the other 2 of 8 servers we received last week. One of the servers had 2 borked fans of 4 and the second one was fine. Henry did the server install since he had a copy of the desktop release and I left before he got the server one.


Thursday I read some more about wireless standards. The chapter discusses the different 802.11 standards with the main ones being 802.11, 802.11a, 802.11b, 802.11g and 802.11n. So within the U.S. of A, Europe and everywhere else the 2.4GHz and 5GHz ranges contain channels which are open to the public so we may enjoy creating our own wireless network. As you can guess 802.11 was the first standard ratified. The more important ones are the b, g and n although b isn't as important anymore which I will explain.

So b and g both operate on the 2.4GHz range. b can give you a maximum of 11Mbps. The reason it has such low bandwith is because it uses the Ethernet based collision detection CSMA/CA. Basically each packet sent requires an acknowledgment which consumes resources.

As stated previously g also operates in the 2.4GHz range and has a maximum data rate of 54Mbps. It uses some magic called Direct Sequence Spread Spectrum that is further into the chapter. The cool the about g is that g devices are backwards compatible with b devices. The bad thing is a b device only works when the other device is in b mode so even if you have 5 g devices and 1 b device connecting to some b/g AP ALL the devices will be limited to 11Mbps.

n is a somewhat recently ratified standard that operates in both the 2.4 and 5 GHz ranges. The biggest thing about n is MIMO is implemented in it which allows a AP to have up to 8 antennas for Multiple-Input Multiple-Output (MIMO).

I'll be back with more wireless standard goodness for next week!

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