LoRa (or LoRaWAN) is by far the best known representative of narrowband communication systems designed for the Internet of Things. As a system dedicated specifically for long-range operations, it possesses a considerable processing gain for the energetic link budget improvement and a remarkable immunity to multipath and interference. The paper describes outcomes of measurement campaigns during which the LoRa performance was tested against these two factors, that is, a heavy-multipath propagation and a controlled, variable interference generated, respectively, in a reverberation chamber and an anechoic chamber. Results allow quantitative appraisal of the system behavior under these harsh conditions with respect to LoRa’s three major configurable parameters: the spreading factor, bandwidth, and code rate. They also allow dividing LoRa configurational space into three distinct sensitivity regions: in the white region it is immune to both interference and multipath propagation, in the light-grey region it is only immune to the multipath phenomenon but sensitive to interference, and in the dark grey region LoRa is vulnerable to both phenomena.
Abstract-The purpose of this paper is to provide some further observations on the use of reverberation chambers to imitate real wireless channels. It is shown, that when RMS delay spread is calculated appropriate threshold has to be chosen. Based on the threshold value the required dynamics of measurements performed for realistic wireless channels can be estimated. It is also shown, that the reverberation chamber loading method allows only for representing outdoor channels.
Network spanning algorithms, such as ZigBee-native and Stojmenovič, constitute a crucial element in the wireless sensor network design, by determining its potential for reliability and fault-tolerance. The interconnections between nodes have a great impact on the radio interference level present in such a network and may create a serious electromagnetic compatibility issue in some cases. It can be proved that the total interference incurred by a statistical node can be diminished in two ways: either by using directional antennas or by setting an upper limit on the duty cycle of each network node.
Abstract-The modeling of the reverberation chamber with the use of deterministic techniques, one of which is the Ray Launching (RL) method, requires a careful tuning with measurements. A few factors that most severely influence the simulation results are: the minimum number of stirrer rotations to produce representative outcomes, the number of reflections of each traced ray and, finally, the size of the receive probe and the wall reflection loss. In the course of investigations it was demonstrated that these factors have a different, and in some instances -even opposite, impact on the simulated results in the electromagnetic (EM) power domain and in the time domain (the time delay spread). A simple procedure consisting of a few steps has been proposed for tuning deterministic RL models to the measured data.
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