A flexible back-end with optimum threshold estimation for OOK based energy detection IR-UWB receivers

Impulse Radio Ultra-Wideband (IR-UWB) exhibits strong advantages in low power and low cost applications such as RFID and Wireless Sensor Networks. This paper presents an on-off keying (OOK) based energy detection IR-UWB receiver with focus on the back-end design. In order to optimize the receiver performance according to different multi-path environment, variable integration interval and adaptive threshold optimization are considered in the proposed back-end which is composed by a programmable timing circuit and a reconfigurable baseband processor. The timing circuit is able to generate multi-phased integration windows with wide-range variable integration interval and is implemented in 90 nm CMOS process. Novel schemes on synchronization and optimum threshold estimation are suggested for baseband processing. The proposed synchronization scheme is based on maximum energy variance (between symbol `0' and `1') detection, covering both the pulse level and symbol level synchronization. And the scheme for optimum threshold estimation is based on look up table, enabling low complexity implementation. System simulation with IEEE 802.15.4a channel models shows an appreciable improvement on the bit error rate (BER) performance compared with the conventional scheme.