With proliferation of wireless services during last decade most of the available spectrum has been allocated. But recent studies revealed considerable spectrum underutilization due to Fixed Spectrum Access (FSA). Cognitive Radio (CR) is an emerging technology aims to solve spectrum scarcity by enabling Dynamic Spectrum Access (DSA) which offers a promising solution to evade spectrum underutilization. Spectrum Mobility or Handoff is an important functionality for practical implementation of CR network. This book scrupulously investigates and analyzes the probability of spectrum handoff under diverse realistic primary and secondary user traffic models. A state of the art standard generalized form of probability of spectrum handoff is established considering secondary user call duration and residual time of spectrum holes as measurement metrics for diverse distribution functions designed for tele-traffic analysis. This book aims to provide a comprehensive understanding about spectrum handoff and its mathematical establishment under various distribution model in CR network.