The correct functionality (can also be called as functional integrity) from a smart device is essential towards ensuring their safe and secure operations. The functional integrity of a device can be defined based on its correctness in sensing and actuating on the physical environment as well as in reporting to the users. As evident from several practical threats (e.g., event spoofing attacks, event masking attacks, sensor failure, vulnerabilities, and misconfigurations), this functional integrity of a device are often breached to cause severe security and safety impacts to their users. To make things worse, such integrity breaches might stay stealthy (due to their non-existence at the user-side) as well as be caused from both devices and apps (due to their vulnerability and misconfiguratons at both physical and cyber spaces). Existing works mainly focus on detecting specific attacks without aiming at verifying functional integrity as a security property. In this paper, we bridge this gap by proposing a continuous approach for smart homes to verify functional integrity at the device-level while monitoring correlated devices. Specifically, our main idea is to learn the correlations among various sensors and actuators in a smart environment, and continuously monitor all the correlated devices to verify functional integrity breaches against various real-world attacks, including spoofing, masking, sensor failure, and device misconfigurations/vulnerabilities. We implement our approach in the context of smart home and evaluate its effectiveness (e.g., for sensors, R2 score of 0.98, and for actuators, accuracy up to 100%) using a public dataset.

Adaptive Demodulation (ADM) is a new rate-adaptive system that operates without requiring Channel State Information (CSI) at the transmitter, instead using adaptive decision region boundaries at the receiver and encoding the data with a rateless code. This paper addresses the design and performance of an ADM scheme for two common differentially coherent schemes: M-DPSK and M-DAPSK. The optimal method for determining the most reliable bits for a given differential detection scheme is presented. In addition, simple (near-optimal) implementations are provided for recovering the most reliable bits from a received pair of differentially encoded symbols for systems using 16-DPSK and 16-DAPSK. The new receivers offer the advantages of a rate-adaptive system, without requiring CSI at the transmitter or a coherent phase reference at the receiver. Bit error analysis for the ADM system in both cases is presented along with numerical results of the spectral efficiency for the rate-adaptive systems operating over a Rayleigh fading channel.

The use of wireless implant technology requires correct delivery of the vital physiological signs of the patient along with the energy management in power-constrained devices. Toward these goals, we present an augmentation protocol for the physical layer of the medical implant communications service (MICS) with focus on the energy efficiency of deployed devices over the MICS frequency band. The present protocol uses the rateless code with the frequency-shift keying (FSK) modulation scheme to overcome the reliability and power cost concerns in tiny implantable sensors due to the considerable attenuation of propagated signals across the human body. In addition, the protocol allows a fast start-up time for the transceiver circuitry. The main advantage of using rateless codes is to provide an inherent adaptive duty cycling for power management, due to the flexibility of the rateless code rate. Analytical results demonstrate that an 80% energy saving is achievable with the proposed protocol when compared to the IEEE 802.15.4 physical layer standard with the same structure used for wireless sensor networks. Numerical results show that the optimized rateless coded FSK is more energy efficient than that of the uncoded FSK scheme for deep tissue (e.g., digestive endoscopy) applications, where the optimization is performed over modulation and coding parameters.

Adaptive demodulation (ADM) is a new rate adaptive technique wherein the receiver demodulates only the most reliable bits and treats unreliable bits as erasures. This paper derives the optimum and simple near-optimum receivers for an ADM system operating without a coherent phase reference, where differential encoding is assumed at the transmitter (using 16-DPSK and 16-DAPSK). The new receivers offer the advantages of a rate-adaptive system, without requiring channel state information at the transmitter or a coherent phase reference at the receiver. Bit error analysis for the ADM system in both cases is presented along with numerical results of the spectral efficiency for the rate adaptive systems operating over a Rayleigh fading channel.

We introduce a rate-adaptive system in which the receiver demodulates only those bits that have a high probability of being correct, treating nondemodulated bits as erasures. Several sets of decision regions, derived using composite hypothesis testing, are proposed for 16-QAM and 16-phase-shift keying, which allow for the simple implementation of this demodulation strategy. We demonstrate that pre-encoding the data with a Raptor code allows for simple reconstruction of the message, regardless of the erasure pattern introduced from the nondemodulated bits. We prove the optimality of the proposed decision regions in selecting the most likely subset of bits from any received symbol in moderate-to-high signal-to-noise ratios, and we analyze the performance of demodulating with these decision regions over an additive white Gaussian noise channel. Also demonstrated is the strong performance of 16-QAM for this application, compared with other power-efficient constellations and the near-optimality of using Gray mapping, even under the proposed alternate sets of decision regions.