The prosperity of IEEE 802.11-based Wi-Fi networks aggravates cross-technology interference to IEEE 802.15.4-enabled ZigBee networks widely deployed to enable various Internet-of-Things applications. To make ZigBee communication reliable and robust even in a dense Wi-Fi environment, taming Wi-Fi interference in ZigBee networks especially from the perspective of physical layer is of paramount importance. In this context, this work takes aim to design a novel Wi-Fi interference-resilient ZigBee decoder called PolarScout, which separates collided ZigBee signal samples out of Wi-Fi interference to bootstrap ZigBee data decoding. Unlike several existing solutions which need clear signal preamble, tremendous signal strength difference between ZigBee and Wi-Fi, and Wi-Fi interference recognition in prior to ZigBee decoding, PolarScout aims at direct ZigBee decoding in a more generic and challenging case where Wi-Fi interference features a wide range of power levels and arises within a ZigBee packet at an arbitrary position. At the heart of PolarScout lies a subtle shell-shaping technique which harnesses a customized sample sequence to smooth the shell of corrupted signal samples. PolarScout then refers to the resulting shell to recover each contaminated ZigBee sample. Experimental results validate the superiority of PolarScout and its resilience to a wide range of Wi-Fi interference types.

Backscatter networks are widely applied in real world such as inventory management, RFID-enabled passport, and access control. The security issues rapidly grow in its importance with the widespread uses. Especially, if the access control application identifies a user using a message from a backscatter device, the message can be used for tracking or replay attacks. However, most of the existing security protocols depending on cryptosystems cannot be applied into the backscatter networks due to the minimalist design of backscatter devices. In order to alleviate the security menaces, we propose a novel concept of authentication scheme for backscatter networks. Our scheme uses an unpredictable collision by applying our own data structure called Shifted Counting Bloom Filter (SCBF). Based on the SCBF, the scheme can reduce the overhead of backscatter devices required for security. Our performance evaluation shows the information-theoretic secrecy and the reliability of our scheme.

The ever-increasing deployment of Wi-Fi and ZigBee networks aggravates cross-technology interference (CTI) in the 2.4 GHz unlicensed spectrum. This letter presents a clean-slate technique, DOTA, to combat the CTI and enable ZigBee/Wi-Fi co-transmission. Unlike existing solutions merely handling Wi-Fi-to-ZigBee interference, DOTA accounts for the true sense of CTI wherein ZigBee and Wi-Fi interfere with each other. At the heart of DOTA lies two operations, signal polishing and pulse disambiguation, for decomposing and threading signal samples to recover contaminated ZigBee and Wi-Fi signals. Experiment results validate the feasibility of superiority of DOTA.