On the human body communications: wake-up receiver design and channel characterization

Abstract

By modulating the electric field induced to a human body, it is possible to transfer data wirelessly using the body as a transmission medium. This method is referred to as human body communication (HBC), which has multiple advantages in comparison with the traditional radio frequency (RF) communication. First, it alleviates the traffic load from the radio channels, which are becoming more and more congested, as the number of connected wireless devices increases rapidly. Second, HBC can potentially provide higher security than traditional RF communication since the electric field stays in the vicinity of a human body, which makes eavesdropping more challenging. Third, the attenuation in the HBC frequency band is lower than in bands used by the other radio technologies for wireless body area networks. To improve energy efficiency in HBC, one approach is to utilize a wake-up receiver (WUR). The WUR is continuously listening for a pre-defined wake-up signal, which activates the other electric circuitry (e.g., sensing, processing, and communication). The use of WURs can significantly reduce the energy consumption and increase the lifetime of the sensing applications. In this work, we propose a superregenerative WUR solution which employs self-quenching and loose synchronization method and operating at sufficiently low (1.25 kbps) data rate in order to obtain high sensitivity while keeping the energy consumption low. This enables to achieve sensitivity of −97 dBm for 10 −3 bit error rate while consuming only 40 μW. The details of the design and the performance evaluation results of the proposed solution are in the paper. Also, the paper reports the results of the practical measurements characterizing the impact of the electrode location on the path loss in an HBC channel. The presented results show that the proposed system can potentially enable communication between two any points on the body with low transmit power.

Energy-Aware System Design for Autonomous Wireless Sensor Nodes: A Comprehensive Review

“…Improving the sensitivity can also be realized with architectures allowing a better filtering of signals, e.g., super-heterodyne (SH) or super regenerative (SR) architectures. The authors of [ 107 ] introduced a SR-based WuRx with a power consumption of 40 μW and a sensitivity of −97 dBm. The decoding mechanism is performed on an off-the-shelf complex programmable logic device (CPLD), requiring much higher power than most recently published WuRx decoders.…”

Energy-Efficient Communication Solutions Based on Wake-Up Receivers

“…In the LPWAN, wireless communications range outdoors can be over 10 km [63] and in indoors one base station can cover a large real-estate [64]. Whereas, in a traditional WSN communications range of the sensor node is usually some tens of meters [65]. Figure 9 shows main differences between the WSN the LPWAN.…”

“…In [60] and [77] authors have shown that hierarchical architecture and its analytical energy efficiency model introduced in [58] can also be applied for WBAN scenario. Further, in [65] the wake-up radio and DCR based network energy consumption comparison is discussed in WBANs case. Here are shown WUR and DCR energy efficiency comparison results which are calculated using four different WUR parameters, which are shown in Table 1.…”

A Tuned-RF Duty-Cycled Wake-Up Receiver with −90 dBm Sensitivity

“…The latter, however, is less of a concern for amplitude modulation schemes. An SR-based WuRx [ 10 ] demands 40 of power and emphasizes an excellent sensitivity of . The decoding mechanism is performed on an off-the-shelf complex programmable logic device (CPLD), requiring much higher power than most of the recently published WuRx decoders [ 1 , 3 , 7 , 8 , 11 , 12 , 13 ].…”