This book aims to address a wide range of topics in wireless communications using Long Term Evolution (LTE) systems. It brings together multidisciplinary contributors in the field of wireless and mobile communications, signal processing and antenna design to identify and present technical challenges and recent results related to the development, integration and enhancement of LTE systems in portable devices. Both state-of-the-art and advanced topics such as LTE femtocells, application of cognitive radio in LTE with efficient sensing mechanisms, interference mitigation and power management schemes for the LTE systems, design challenges and approaches for the LTE antennas, performance enhancement techniques used for such antennas and effects of user’s presence on these antennas are discussed to highlight advancements in this exciting field.