The complexity of RFID systems has been increasing continuously. New applications are emerging, where the tags are extended by arbitrary sensors, the collection of data from low class tags, the communication between the tags and the support of Real-Time Localization Systems (RTLS). These new applications require active RFID tags, where a battery powers the tag. New communication techniques have to be evaluated for these tags to satisfy their requirements. Active RFID tags are currently extremely expensive so the focus is on simple and low complexity techniques to reach new market segments. The tags have to operate in highly multipath intensive environments, where the signal is severely distorted. The project investigates radio air-interface technologies for active RFID-RTLS. New Communication methods like Ultra Wideband (UWB) are expected to fulfill the requirements of such systems, because UWB enables the tracking of goods with cm accuracy, shows good robustness against multipath fading, and enables very low power transmission. However, most of the known receiver architectures show high complexity and are not applicable in RFID. A goal of this work is an analysis of UWB receiver architectures, their usability in active RFID systems and the development of new suboptimal low complexity UWB architectures. The transceiver architectures, signaling schemes and positioning techniques based on UWB will be compared with other state of the art communication technologies.