What is OFDM and COFDM ?
Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier transmission
technique, which divides the available spectrum into many carriers, each one being
modulated by a low rate data stream. OFDM is similar to FDMA in that the multiple user
access is achieved by subdividing the available bandwidth into multiple channels, that
are then allocated to users. However, OFDM uses the spectrum much more efficiently
by spacing the channels much closer together. This is achieved by making all the
carriers orthogonal to one another, preventing interference between the closely spaced
Coded Orthogonal Frequency Division Multiplexing (COFDM) is the same as OFDM
except that forward error correction is applied to the signal before transmission. This is
to overcome errors in the transmission due to lost carriers from frequency selective
fading, channel noise and other propagation effects. For this discussion the terms
OFDM and COFDM are used interchangeably, as the main focus of this thesis is on
OFDM, but it is assumed that any practical system will use forward error correction, thus