Abstract
The wireless sensor nodes used in a growing number of remote sensing applications are deployed in inaccessible locations or are subjected to severe energy constraints. Audio-based sensing offers flexibility in node placement and is popular in low-power schemes. Thus, in this paper, a node architecture with low power consumption and in-the-field reconfigurability is evaluated in the context of an acoustic vehicle detection and classification (hereafter “AVDC”) scenario. The proposed architecture utilizes an always-on field-programmable analog array (FPAA) as a low-power event detector to selectively wake a microcontroller unit (MCU) when a significant event is detected. When awoken, the MCU verifies the vehicle class asserted by the FPAA and transmits the relevant information. The AVDC system is trained by solving a classification problem using a lexicographic, nonlinear programming algorithm. On a testing dataset comprising of data from ten cars, ten trucks, and 40 s of wind noise, the AVDC system has a detection accuracy of 100%, a classification accuracy of 95%, and no false alarms. The mean power draw of the FPAA is 43 μ W and the mean power consumption of the MCU and radio during its validation and wireless transmission process is 40.9 mW. Overall, this paper demonstrates that the utilization of an FPAA-based signal preprocessor can greatly improve the flexibility and power consumption of wireless sensor nodes.
Highlights
A field-programmable analog array (FPAA) is a reconfigurable integrated circuit (IC) that is the mixed-signal analogue to a field-programmable gate array (FPGA); while FPGAs allow for post-fabrication synthesis of digital circuits, FPAAs allow for the post-fabrication synthesis of analog circuits [27,28,29]
Once the microcontroller unit (MCU) makes the final decision on the vehicle type, a radio transmission is sent
A low-power reconfigurable wireless sensor networks (WSNs) node architecture centered on an FPAA-based mixed-signal preprocessor and a panStamp MCU was presented in this paper
Summary
The rapid rise of the Internet of Things (IoT) has facilitated the advancement of remote sensing by simplifying the design and expanding the scale of wireless sensor networks (WSNs) [1,2,3,4,5]. This paper proposes a hybrid node architecture comprising of an always-on, mixed-signal processor (MSP) and a microcontroller unit (MCU) that is only awoken when a significant event is detected by the MSP In this way, the intrinsic device physics of analog components are leveraged to perform computations that would inherently require more power on fully digital platforms while still retaining the abilities to wirelessly network and perform sophisticated digital computation. ASIC development is time-consuming and ASIC-based solutions can be limited in their ability to handle future changes to procedures or overall tasks These issues are mitigated in this paper by using a low-power field-programmable analog array (FPAA).
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