In recent years, promising results have been reported with the vibrating intrinsic reverberation chamber (VIRC) combining performance and cost-efficiency for electromagnetic compatibility (EMC) measurements. This also makes it a potentially attractive solution for over-the-air (OTA) testing, which is yet to be investigated. Therefore, this article proposes the first systematic and thorough methodology to characterize the VIRC for use in EMC and OTA testing of wireless baseband algorithms of narrowband single-input single-output channels. This methodology has been developed to measure and estimate the channel first-and second-order temporal and spectral characteristics taking into consideration the effect of different carrier frequencies, rotational speeds of VIRC motors, and loading conditions. It is then applied to a channel setup inside a VIRC for a preliminary investigation before the VIRC itself is fully characterized. It is shown that mounting an absorber in a specific location on the hatch significantly improves the rejection rate of the chi-squared goodness-of-fit test for Rician distribution without increasing the K-factor above −10 dB over the frequency range 755-2740 MHz in the VIRC under investigation. However, the proposed methodology has been devised to be universal to any reverberation chamber, and the obtained results can be used to improve EMC testing due to the better understanding of the unique VIRC environment.

In wireless sensor networks, the need for ultra-low power consuming nodes is one of the main motivations for research in such field. Because radio sections in sensor nodes contribute to a large extent to the overall power consumption, the focus of this study is on the RF transceiver. The aim is to reduce the average power consumption which depends significantly on the circuit architecture design, operating data rate, and duty cycle. In a symmetric communicating system, due to the tradeoff between transmitting power and receiver sensitivity on one hand, as well as between phase noise tolerance and power dissipation in local oscillators on the other hand, the design and operating parameters of the transceiver need to be determined from the perspective of the average power consumption. Therefore, in our study, as an initial step in system design, the optimum for instantaneous data rate, noise figure, and oscillator power budget are analytically determined. The analysis is carried out, taking into consideration an existing in-channel wideband interference, on two transceiver architectures: RF envelope detection and conventional heterodyne. The transceiver in both architectures employs on-off-keying modulation and duty cycling. The optimums are then calculated numerically based on design constants obtained from a frequently-cited RF envelope transceiver, indicating that an energy efficiency improvement of up to 5 dB can still be achieved.

We develop a systematic methodology to experimentally investigate the impact of interference from a nonlisten-before-talk ultra-narrowband (UNB) signaling technique on Wi-Fi links. The methodology is based on a worst-case interference scenario, and consists of three investigating steps. This methodology is then applied to a measurement setup to practically study the case of 100 bps UNB signals interfering with an IEEE 802.11n transmission in the 2.4 GHz band. Five different Wi-Fi devices are tested. The UNB signal is generated in two modulation schemes, the on-off-keying (OOK) and the Gaussian minimum-shift-keying. Both single and multiple simultaneous UNB interferers are considered. An analysis of the measurement results shows that three of the tested Wi-Fi devices cannot coexist with the considered non-listen-before-talk UNB communication system. The throughput performance analysis of the other tested devices shows that the OOK-modulated UNB signal has the least interfering impact, and the Wi-Fi pilot subcarriers are the most vulnerable to UNB interference. However, if a single UNB interferer avoids these subcarriers and employs the OOKmodulation scheme, then wireless coexistence is possible as long as the signal-to-interference ratio of Wi-Fi to UNB is greater than 30 dB, given that a drop to 75% of the maximum Wi-Fi throughput is acceptable.

<p>Electromagnetic compatibility (EMC) measurements and over-the-air (OTA) testing are widely performed in classical reverberation chambers. A less-known reverberation chamber, yet a rather efficient environment for generating multipath conditions, is the Vibrating Intrinsic Reverberation Chamber (VIRC), which is yet to be fully characterized. Therefore, this article thoroughly investigates a propagation channel inside a VIRC in terms of its first- and second-order temporal and spectral characteristics for EMC measurements and OTA testing of wireless baseband algorithms in narrowband single-input single-output systems. The investigated characteristics are coherence time, Doppler spectrum, Doppler spread, frequency autocovariance function, coherence bandwidth, rejection rate of Chi-squared goodness-of-fit test for Rician distribution, Rician 𝐾-factor, and channel gain. The investigation considers the effect of different rotational speeds of the VIRC motors, two loading conditions, and the frequency range 670 – 2740 MHz. An analysis of the measurement results shows that the stirring effectiveness degrades at frequencies below 820 MHz in general. For the loaded VIRC in particular, rotational speeds below 28.3 rpm are another degradation contributor. Moreover, the analysis reveals many interesting behavioral trends. This in turn is used to introduce a number of mathematical models closely fitting the behavior of various of the investigated characteristics. Such models are useful, for instance, at shortening similar measurement campaigns of comparable VIRCs.</p>

Industrial and consumer applications, such as smart energy and e-wearables, have become a realitythanks to the Internet of Things and wireless sensor networks-creating a billions-worth market. Very-largescale integration combined with energy scavenging give a promising ultra-low-power, cost-effective, and environment-friendly solution for the increasing power consumption demands as tens of millions of nodes are deployed worldwide every year. Most available wireless standards are power-hungry and, therefore, not suitable for energy scavenging. In this paper, we motivate ultranarrowband as an energy-scavenging-compatible wireless technology for low-throughput wireless sensor networks (WSNs). The ultra-narrowband approach is energyefficient for two case scenarios. The first one is for WSNs with a large coverage area. The second case scenario is where WSN nodes experience a high level of interference from other co-existing communication systems. Two practical use cases are studied numerically, one for each case scenario. In both cases, on a node level, the link is significantly imbalanced between the transmitting and receiving sections in terms of energy consumption and data rate. However, in case of an interference-rich environment, the radiated power from the WSN base station as well as the WSN nodes is preferred to be as low as possible, thus leading to a more balanced link.