  Time synchronization is a vital concern for any Cognitive Radio Network (CRN)
to perform dynamic spectrum management. Each Cognitive Radio (CR) node has to
be environment aware and self adaptive and must have the ability to switch
between multiple modulation schemes and frequencies. Achieving same notion of
time within these CR nodes is essential to fulfill the requirements for
simultaneous quiet periods for spectrum sensing. Current application layer time
synchronization protocols require multiple timestamp exchanges to estimate skew
between the clocks of CRN nodes. The proposed symbol timing recovery method
already estimates the skew of hardware clock at the physical layer and use it
for skew correction of application layer clock of each node. The heart of
application layer clock is the hardware clock and hence application layer clock
skew will be same as of physical layer and can be corrected from symbol timing
recovery process. So one timestamp is enough to synchronize two CRN nodes. This
conserves the energy utilized by application layer protocol and makes a CRN
energy efficient and can achieve time synchronization in short span.
