Radio Channel Characteristics of Zigbee Wireless Sensors in Machine Shop for Plant Floor Process Monitoring

Author(s):  
Lei Tang ◽  
Kuang-Ching Wang ◽  
Yong Huang ◽  
Fangming Gu

Wireless sensors are envisioned to be useful for plant floor process monitoring with unprecedented flexibility and low costs, where data can be relayed via a wireless network formed among the sensors. Factory environments, however, are known harsh for radio communications. For sensor radios engineered with extremely low power and simple circuitry, the sensor radio channel characteristics must be identified for optimal network design and reliability assessment. In this paper, a preliminary radio channel measurement study was performed based on the wireless sensor pairs in normal communication at the 2.4 GHz Industrial, Scientific and Medical (ISM) band to assess the sensor radio channel properties in a university machine workshop. The effect of both stationary and moving (forklift) obstacles on the radio propagation in terms of the received signal power, bit error and packet error rates was studied. The effect of stationary obstacles was further analyzed against a simple path loss model to find the path loss exponent. A spectrum analyzer was also used to capture the noise backgrounds in free space and the machine shop, which shows significantly different radio activities among the investigated scenarios. The proposed channel measurement methodology through directly utilizing the sensor platforms will help future radio channel characterization studies in manufacturing plant floor environments.

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jinmeng Zhao ◽  
Lei Xiong ◽  
Danping He ◽  
Jiadong Du

The tunnel scenario is a major rail communication scenario. In this paper, the radio channel characteristics of tunnel scenarios with different carrier frequencies, different distances between the transmitter (Tx) and receiver (Rx), and cross sections are simulated with a ray-tracing tool. Key parameters such as path loss, Rician K-factor, root mean square (RMS) delay spread, and angular spread are studied. According to the results, higher frequencies introduce larger path loss and the presence of the vehicle body increases the path loss by about 35 dB in the scenario; at the same time it will also cause the fluctuation and instability of the path loss. Besides, the influence of reflections from the side walls is significant on radio propagation. The channel experiences more severe fading in a narrow tunnel compared with others.


Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3626
Author(s):  
Fang Li ◽  
Wei Chen ◽  
Yishui Shui

The vehicle-to-vehicle (V2V) radio channel is non-stationary due to the rapid movement of vehicles. However, the stationarity of the V2V channels is an important indicator of the V2V channel characteristics. Therefore, we analyzed the non-stationarity of V2V radio channels using the local region of stationarity (LRS). We selected seven scenarios, including three directions of travel, i.e., in the same, vertical, and opposite directions, and different speeds and environments in a similar driving direction. The power delay profile (PDP) and LRS were estimated from the measured channel impulse responses. The results show that the most important influences on the stationary times are the direction and the speed of the vehicles. The average stationary times for driving in the same direction range from 0.3207 to 1.9419 s, the average stationary times for driving in the vertical direction are 0.0359–0.1348 s, and those for driving in the opposite direction are 0.0041–0.0103 s. These results are meaningful for the analysis of the statistical characteristics of the V2V channel, such as the delay spread and Doppler spread. Small-scale fading based on the stationary times affects the quality of signals transmitted in the V2V channel, including the information transmission rate and the information error code rate.


Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4112
Author(s):  
Fidel Alejandro Rodríguez-Corbo ◽  
Leyre Azpilicueta ◽  
Mikel Celaya-Echarri ◽  
Peio Lopez-Iturri ◽  
Ana V. Alejos ◽  
...  

The characterization of different vegetation/vehicle densities and their corresponding effects on large-scale channel parameters such as path loss can provide important information during the deployment of wireless communications systems under outdoor conditions. In this work, a deterministic analysis based on ray-launching (RL) simulation and empirical measurements for vehicle-to-infrastructure (V2I) communications for outdoor parking environments and smart parking solutions is presented. The study was carried out at a frequency of 28 GHz using directional antennas, with the transmitter raised above ground level under realistic use case conditions. Different radio channel impairments were weighed in, considering the progressive effect of first, the density of an incremental obstructed barrier of trees, and the effect of different parked vehicle densities within the parking lot. On the basis of these scenarios, large-scale parameters and temporal dispersion characteristics were obtained, and the effect of vegetation/vehicle density changes was assessed. The characterization of propagation impairments that different vegetation/vehicle densities can impose onto the wireless radio channel in the millimeter frequency range was performed. Finally, the results obtained in this research can aid communication deployment in outdoor parking conditions.


2012 ◽  
Vol 60 (7) ◽  
pp. 3397-3406 ◽  
Author(s):  
Max O. Munoz ◽  
Robert Foster ◽  
Yang Hao

Author(s):  
Kaveh Pahlavan ◽  
Yunxing Ye ◽  
Ruijun Fu ◽  
Umair Khan

In this invited paper, the authors introduce an overview of the fundamentals of radio frequency (RF) channel measurement and modeling techniques needed for localization inside the human body. To address these fundamentals, the authors use capsule endoscopy as an example application. The authors first provide the results of the Cramer Rao Lower Bound (CRLB) for received signal strength (RSS) based endoscopy capsule localization, inside the human body, using existing path-loss models for radio propagation. Then challenges demanding further research are highlighted for attaining more precise localization using the time-of-arrival (TOA) based ranging techniques.


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