Precise determination of the mobile position constitutes the basis of several novel applications. This book presents a descriptive account of wireless systems for signal processing, performances assessment, positioning, localization applications, etc. It also discusses satellite systems for positioning such as GNSS, GPS, etc. as well as localization applications employing the wireless sensor networks. Certain methodologies are presented for localization systems, specifically for indoor positioning, like Ultra Wide Band (UWB), WiFi. The book also discusses coupled GPS and other sensors. Some results of tests, simulations and implementation are provided to assist readers in comprehending the described techniques. This book is intended for a wide spectrum of readers including PhD research scholars, engineers and academics engaged in this extensive field.