Select the correct statement(s) regarding direct sequence spread spectrum (DSSS) and orthogonal frequency division multiplexing (OFDM). a. OFDM is not classified as a spread spectrum technique, although OFDM has the effect of spreading the signal over a larger frequency spectrum
b. OFDM has greater spectral efficiency compared to DSSS
c. DSSS relies upon a PN code that is only shared by the transmitter and receiver pair
d. all statements are correct

a. OFDM is not classified as a spread spectrum technique, although OFDM has the effect of spreading the signal over a larger frequency spectrum.

Explanation:

Orthogonal Frequency Division Multiplexing is a technique in which large digital data is sent over radio waves by splitting it into multiple subcarriers. The data is then transmitted to different users who can access the files. OFDM is not a spread spectrum technique, it is based on large frequency spectrum.