Quaternion Model of Higher-Order Rotating Polarization Wave Modulation for High Data Rate M2M LPWAN Communication

With growing interest in Industry 4.0, machine-to-machine communication (M2M) will become the key enabler for low-power wide area networks (LPWANs) in connecting machines and sensor nodes distributed across a distance in the industrial environment. The choice of modulation and diversity techniques, and the selection of spectrum (licensed/unlicensed) will impact and influence the requirements of wireless M2M systems. Link reliability is one of the most important requirements for LPWAN deployment in industrial scenarios. Rotating Polarization Wave (RPW) system has been recently proposed as an LPWAN solution for reliable M2M communication in high clutter environment and it deploys BPSK modulation with polarization diversity (PD). This paper proposes a new multi-level Rotating Polarization Phase-Shift Keying (RP-MPSK) modulation to provide high data rate and energy efficiency. A novel quaternion model for RPW system (Q-RPW) is also proposed to reduce the complexity in modeling, simulation, and implementation. Results using Q-RPW model show that RP-MPSK modulation offers a high diversity gain over BPSK with second-order diversity. Bit error rate (BER) performance of RP-MPSK modulation compared against other LPWAN modulation like MPSK, FSK and QAM has shown high reliability and substantial improvement in SNR. To overcome the degradation in error performance caused by the proposed higher-order modulation, sampling rates are recommended based on BER performance. BER performance of RP-MPSK under multipath and interference conditions is also investigated.

Multiscale modelling of motility wave propagation in cell migration

The collective motion of cell monolayers within a tissue is a fundamental biological process that occurs during tissue formation, wound healing, cancerous invasion, and viral infection. Experiments have shown that at the onset of migration, the motility is self-generated as a polarization wave starting from the leading edge of the monolayer and progressively propagates into the bulk. However, it is unclear how the propagation of this motility wave is influenced by cellular properties. Here, we investigate this using a computational model based on the Potts model coupled to the dynamics of intracellular polarization. The model captures the propagation of the polarization wave initiated at the leading edge and suggests that the cells cortex can regulate the migration modes: strongly contractile cells may depolarize the monolayer, whereas less contractile cells can form swirling movement. Cortical contractility is further found to limit the cells motility, which (i) decelerates the wave speed and the leading edge progression, and (ii) destabilises the leading edge into migration fingers. Together, our model describes how different cellular properties can contribute to the regulation of collective cell migration.

Analysis of shielding effectiveness in different kinds of electromagnetic shielding fabrics under different test conditions

This study used the DR-SO4 window method to test the shielding effectiveness of silver-plated fiber functional fabric, copper–nickel duplicate coating fabric, and stainless steel fiber-blended-type fabric. These electromagnetic shielding fabrics exhibited different levels of shielding effectiveness under different polarization directions. In the same frequency, the shielding effectiveness difference between the vertical polarization wave direction and horizontal or 45° polarization wave direction is higher in silver-plated fiber functional fabric and copper–nickel duplicate coating fabric than that in stainless steel fiber-blended fabric. The radiation distance of 1.5 m has great influence on the shielding effectiveness of the three fabrics. These fabrics show a repeated and intersected change in wrinkle degrees of 1# and 2#. The fabrics in the wrinkle degree of 2# have higher shielding effectiveness than that of 3#. The wrinkle recovery properties of electromagnetic shielding fabrics also affect their shielding effectiveness. The shielding effectiveness of copper–nickel duplicate coating fabric with low wrinkle recovery property considerably changes. This research provides a basis for the design of electromagnetic shielding fabrics.