Ahh welcome to the world of wireless.
I am often confused by the explanations people try to use.
Honestly I would ignore everything to do with DSSS in the real world, and just remember that one bit is spread into 11. This actually changes as you go from 1-2-5.5-11, but you get the idea. The End. Review it for the exam, then forget it.
A symbol is the fundamental building block of OFDM, and takes 4us. (3.6 if you have SGI turned on). It has a quiet period (Guard Interval) then bursts data on all the subcarriers for a short time (symbol time - Guard Interval).
That's it, now you know what a symbol really is. Ignore all the stuff where people try to explain DSSS and CCK spreading as a symbol.
My opinion is to turn off "b" anyway, so there is no DSSS. (Now that should start some comments coming in).
Thanks for the reply, Phil.
As you said, they’re not going to go in-depth in to DSSS in the exam – but it’s more that I’d like to know why Symbols and Chips are mentioned interchangeably, and inconsistently between publications.
I’ve looked through the following books to find a definitely or unifying explanation, but unfortunately they seems to, at some stage or another, contradict each other.
CCNA Wireless 640-722 Official Cert Guide
CCNA Wireless Official Exam Certification
Scalable VoIP Mobility
CCNA Wireless 200-355
RF Engineering for Wireless Networks
802.11 Wireless Networks: The Definitively Guide, 2nd Edition