As the demand for sophisticated wireless mobile applications incorporating efficient modulation techniques is ever increasing, the more spectral bandwidth is needed so that more number of applications could work. However, bandwidth is scarce in nature. Also, as the existing spectrum allocation policies of the Federal Communications Commission (FCC) allow spectrum access to licensed users only, it has been proven by various spectrum measurement campaigns that, the current licensed system uses its total spectrum inefficiently.Spectrum pooling is the concept which is based on dynamic spectrum access (DSA), wherein the secondary user decides whether the particular frequency band is currently being used and transmits the signal in that unused licensed band or not, while keeping in mind that the system performance of the primary as well as the secondary is not getting worst. Thus, coexistence of the primary and the secondary users is an important criterion that makes DSA a feasible solution for efficient spectrum usage.