Efficient utilization of frequency bands has attracted more and more attention. Most of the licensed spectrum nowadays is under-utilized and some unlicensed services are allowed to use the available spectrum without causing harmful interference to the primary users. Therefore, unlicensed users should be able to detect spectrum holes reliably. Spectrum sensing and estimation is an important factor to achieve this. In this thesis, several spectrum sensing and estimation methods are compared based on receiver operating characteristics. Simulation results show that there is a trade-off among different methods.