wimax sampling factor
The sampling factor 8/7 in Wimax is used to increase data rate. The story is that in Wimax there is guard tone at each end of IFFT (the number of guard tone has some historic reasons. Anyway, it is kind of fixed.). It is found out that in doing so we are too conservative in using IFFT tones. So, Wimax proposes sampling factor >1 to increase data rate.
The only place you can find this explanation is in the book written by 802.16 committee. It is called "IEEE 802.16, inside..." try Amazon