Wireless communications systems are evolving to be more diverse in use and more ubiquitous in nature. It is of fundamental importance that we consume the resources available in such systems, i.e., bandwidth and energy, to preserve room for more users and to preserve longevity. Signal processing can greatly help us achieve this. In this book we consider improving the utility of resources available in wireless communications systems, by various means. This book proposes several novel signal processing algorithms in blind channel estimation, cooperation and in energy reduction, to achieve this.