II. BASEBAND OVER FIBER TRANSMISSION SCHEME
The BBOF transmission scheme is used to transport radio
frequency (RF) wireless signals as a baseband signal over
fiber. The system then modulates the decoded baseband signal
to the required radio frequency only at the AP as shown in
Figure 2. In this scheme, the transmitted downstream data
is upconverted directly by optical modulator and propagates
as a baseband signal over optical fiber. The AP receives the
baseband optical signal which is directly detected and decoded
by a photodiode (PD), a low pass filter (LPF), and decoder. The
decoded bit downstream is then modulated by the RF modem
at the carrier frequency f RF. In the upstream direction, the
RF modem receives the uplink wireless signal at the AP, and
then decodes it to a bit upstream which is send back to the
CO as a baseband signal over fiber