The third problem is simplifying SS.SS as a receiving end
is a combination joint of wire and wireless communication. On
the one hand, it sends downlink signal to the terminal, on the
other hand, it sends the signal from terminal to BS. Since the
free-space attenuation of 3.5GHz RF signal is drastic, the
coverage of SS becomes smaller. So, the WiMAX system
using RoF needs large amount of SS to fulfill seamless
coverage in a WMAN so that the SS module should be
simplified to lower the power consumption and cost of the
system. EAT (Electronic Absorption Transceiver) can be used
to provide optical carrier for uplink in order to remove optical
source from SS to simplify structure and lower the cost of the
system.