LTE-NB : OFDM Signal Generation
As in normal LTE, LTE-NB downlink is using OFDM waveform as well. I put the LTE-NB OFDM waveform generation formula and LTE formula toghether for comparision. You may think there is a big difference between the two, but actually not so much difference. It looks like LTE OFDM formular is much more complicated.. but it just look like complicated. It just divided one formular into two terms (sections) to remove center subcarrier (DC carrier). But in LTE-NB, there is no DC removal part, so it can represent the whole formular in single term. In other words, in LTE k never gets to 0 (the formula is not defined at k = 0), but in LTE-NB the formula is defined at k = 0 as well.