Microcontroller implementation of low-complexity wake-up receiver for wireless sensor nodes in severe multipath fading channels

Abstract

This paper proposes a low-complexity dual pseudorandom noise (PN) scheme for identity (ID) detection and coarse frame synchronization. The two PN sequences are identical and are separated by a specified length of gap which serves as the ID for different sensor nodes. The receiver ID detection is implemented on a microcontroller MSP430F5529 by calculating the correlation between the two segments of the received signal with the specified separation gap. When the gap length is matched with the ID, the correlator outputs a peak which sets the wakeup enable. The time index of the correlator peak is used as the coarse synchronization of the data frame. An iterative algorithm is used that requires only one multiplication and two additions for each sample input regardless of the length of the PN sequences, thus achieving low computational complexity. The proposed dual PN detection scheme has been successfully tested by simulated fading channels and real-world measured channels. The results show that, in long multipath channels with more than 60 taps, the proposed scheme achieves high detection rate and low false alarm rate using maximal-length sequences as short as 31 bits to 127 bits, therefore it is suitable as a low-power wake-up receiver.