Sub-Nyquist Sampling Impulse Radio UWB Receivers for the Internet-of-Things

Sammanfattning: In the era of Internet-of-Things, the demand for short range wireless links featured by low-power and low-cost, robust communication and high-precision positioning is growing rapidly. Impulse Radio Ultra-Wideband (IR-UWB) technology characterized by the transmission of sub-nanosecond pulses spanning up to several GHz band with extremely low power spectral density emerges as a promising candidate. Nevertheless, several challenges must be confronted in order to take the full advantage of IR-UWB technology. The most significant one lies in the reception of UWB signals. Traditional receiver requires Nyquist rate ADC which is overwhelmingly complex and power hungry. This dissertation proposes and investigates possible sub-Nyquist sampling techniques for IR-UWB receiver design.In the first part of this dissertation, the IR-UWB receiver based on energy detection (ED) principle is explored. A low-power ED receiver featured by flexibility and multi-mode operation is proposed. The receiver prototype for 3-5 GHz band is implemented in 90 nm CMOS. Measurement results demonstrate that 16.3 mW power consumption and -79 dBm sensitivity at 10 Mb/s data rate can be achieved. To further optimize the receiver performance, threshold optimization is suggested for the on-off-keying modulated signal, and adaptive synchronization and integration region optimization is proposed. Finally, a low complexity burst packet detection scheme is proposed, which is adaptive to the variations of noise background and link distance.In the second part of this dissertation, the IR-UWB receiver based on compressed sensing (CS) theory is investigated. Firstly, appropriate sparse basis, sensing matrix and reconstruction algorithms are suggested for the CS based IR-UWB receiver. And then, the architectural analysis of the CS receiver with focuses on the random noise processes in the CS measurement procedure is presented. At last, a novel two-path noise-reducing architecture for the CS receiver is proposed. Besides the improvement on the receiver performance, the proposed architecture also relaxes the hardware implementation of the CS random projection as well as the back-end signal reconstruction.