Christian Doppler Labor
für digital unterstützte Hochfrequenz-Transceiver in zukünftigen mobilen Kommunikationssystemen
The Christian Doppler Laboratory for Digitally Assisted RF Transceivers for Future Mobile Communications is dedicated to basic and applied research on digital signal processing (DSP) methods for radio frequency (RF) transceivers. With current Complementary Metal-Oxide-Semiconductor (CMOS) technology, DSP methods are perfectly suited to compensate analog imperfections appearing in RF circuits, to introduce advanced signal processing methods not possible with analog circuits, and to benefit from technology scaling in terms of computing performance, power consumption and chip area.
RF transceivers in current commercial products already make use of DSP. The continuously increasing requirements for mobile devices, e.g. from the current 4th generation (4G) mobile communications standard “Long Term Evolution” (LTE) and the future 5G standard, will strongly increase this need in future developments. A common result of these requirements is both a significant rise in complexity of the transceiver architectures and an exponentially increasing number of possibilities for self-interference. We will tackle these issues by making use of DSP and focus our research in three areas:
- Receiver Interference Cancellation: We will research methods to identify and cancel interference in an adaptive manner in the receiver
- Energy Efficient Digitally Assisted Transmitter Architectures: Digitally assisted transmitter architectures need to be explored to accommodate channel bandwidths well beyond 20 MHz for high data rate applications
- All-digital Phase-locked Loops: Improved all-digital phase-locked loops (ADPLLs) are required, e.g. to reduce the number of digitally controlled oscillators in a transceiver chip. Furthermore, the reduction of the power consumption of ADPLLs is targeted to enable low-cost RF transceivers for Internet of Things devices.
While each of these three strands of research has its own specifics, complexity and interference issues are linking them together and making them to some extent depend on each other. Furthermore, system-level time- and frequency domain modeling and statistical signal processing methods are common research methods applied across the different topics.
Expected outcomes of our CD-laboratory are DSP methods for RX, TX and ADPLL which allow the realization of RF transceivers fulfilling the increasing requirements on user experience like data rate and seamless connectivity while reducing chip area, power consumption and design complexity.