In order to meet the challenges discussed above, with the
use of the presented concepts, we have designed a dynamic
spectrum access and allocation protocol (DSAAP) that allows
for coordinated operation of a dynamic spectrum access network
deployed in whitespaces for OFDM-based systems. In
general, the DSAAP operations are performed as follows (the
subsequent steps are also depicted in Figure 2): 1) When a
new whitespace device that is able to connect to the Internet
is switched on, it checks with the geo-location database for
any available frequency channels. 2) If there are no other
whitespace devices operating in the coverage region of the
device and a channel is found, the device reserves this particular
channel for secondary spectrum operation and becomes a
whitespace access point. In the case that a whitespace access
point is already operating in the coverage region, the device
has to make a decision on whether or not to take the role of
a whitespace access point. In this work we assume that every
device that is able to connect to the Internet will become a
whitespace access point, and we leave other decision schemes
for future studies. A whitespace access point periodically
transmits a broadcast signal that announces the availability of
the whitespace access point in the specific frequency channel to
any other whitespace devices. The transmitted broadcast signal