International Journal of Sensors Wireless Communications and Control - Volume 13, Issue 1, 2023

Background: The cell-free massive multiple input multiple outputs (CF M-MIMO) is the key and emerging technology for 5G and beyond, which gains more attention from many researchers and academicians. The cell-free M-MIMO enhances the system throughput, latency, spectral efficiency (SE), and energy efficiency (EE) of the communication network. Objective: In this paper, we formulate a framework for joint access point selection (APS) and power control algorithm for improving the EE and at the same time maintaining the system capacity. Methods: The max-min power control algorithm is used for efficient power allocation among the access points (APs) by using the minimum mean square error (MMSE), zero-forcing (ZF), and conjugate beam-forming (CB). Results: We were successfully able to enhance and maintain the optimal system capacity of the cellfree M-MIMO systems. Conclusion: The simulation result shows that the system capacity is improved when efficiently allocating the power with max-min power control algorithm.

Background: Sensorless control of permanent magnet synchronous motor (PMSM) at low speed remains a challenging task. Introduction: In this paper, a sensorless vector control of PMSM using a new structure of a back EMF sliding mode observer (SMO) is proposed. Methods: To remove the mechanical sensors, a back EMF-SMO is built to estimate the rotor position and speed of PMSM drives. The SMO, which replaces a sign function with a sigmoid function, can reduce the chattering phenomenon. This sensorless speed control shows great sensitivity to stator resistance and system noise. Results & Discussion: To improve the robustness of sensorless vector control, the back EMFSMO technique has been used for stator resistance estimation. A novel stator resistance estimator is incorporated into the sensorless drive to compensate for the effects of stator resistance variation. Conclusion: The validity of the proposed SMO with a 1.1 kw low-speed PMSM sensorless vector control has been demonstrated by real experiments.

Background: A number of disciplines, including security, healthcare, and human-machine interactions, have presented and used techniques for emotion recognition based on facial expressions. Objective: To increase computer prediction, researchers are advancing the methods for deciphering code and extracting facial emotions. Methods: The contamination of the image with noise, which alters the features of the images and ultimately impacts the accuracy of the system, is one of the major issues in this sector. Thus, noise should be eliminated or diminished. The wavelet transform approach is used in this study to denoise the images before categorization. The classification accuracies for original images are also obtained to analyze the effect of denoising on the classification accuracy of the facial expression images. Results and Conclusion: Three machine learning approaches, support vector machine, k-nearest neighbor, and naive bayes, are utilized to classify the emotions in this instance. The feature employed is the histogram of directional gradients of images. The classification results are obtained and the effect of denoising on the classification accuracy of the facial expression images is analyzed. Also, our best-obtained result for the wavelet transform method is compared with other wavelet transform-based facial emotion recognition techniques. And our result is found to be promising.

Background: The Internet of Things (IoT) is an embryonic model that converts realworld things (objects) into smarter devices. IoT is applicable to a variety of application domains, including healthcare, smart grid, and agriculture. Low Power Wide Area Network (LPWAN) technology can transmit data over long distances with a low data rate without using the internet. Therefore, this technology is suitable for sending sensor measurement data in Internet of Things (IoT) applications. LPWANs, such as LoRa, use a star topology to reach their coverage to the maximum power that can be transmitted, considering the environmental conditions in the test area and the LoRa parameters used. Whereas for application development in rural areas, there is no internet connection, and often longer coverage is required from the sensor node to the gateway. Objective: This study aims to increase the transmission range from the end node to the gateway by adding an intermediate node. It is used as a relay from the end node to the gateway. Method: Static routing was applied so that any broadcast data from the end node would be forwarded first to the intermediate node and then to the gateway. Results: The LoRa transmission range expanded by changing the topology from peer-to-peer to multi-hop. An intermediate node between the transmitter (end node) and the gateway is available. In the experiment performed, a multi-hop with static routes successfully expanded the distance from 150 meters (single hop) to 250 meters (multi-hop), with a packet delivery ratio of 97%. In this experiment, GPS Ublox Neo was used for the sensor position and was successfully tested on the end node with an accuracy rate of 2.4% for latitude and 0.2% for longitude. Conclusion: The transmission range from the sensor node to the gateway can be extended using static routing by installing an intermediate node between the gateway and the sensor node. The data from the end node is successfully received by the gateway.

Aim: The aim of this study is the deployment of components in an efficient manner to make a cost-effective FiWi network. Background: Fiber Wireless access network is the boost to broadband access technology for providing network services to Internet users at a lower cost. Deployment of components in FiWi access network is very crucial since it affects the deployment cost and network performance. Objective: We investigate the planning process for efficient placement of components in FiWi access networks. For optimizing the position of components (wireless routers and ONUs) in the network, a novel nature inspired Reptile Search Algorithm (RSA) is proposed in the paper. Methods: Extensive simulation is carried out to implement proposed work. A simulation model and code is developed in MATLAB to get the optimized position of components for existing and proposed algorithms. Results: We compare the performance of proposed algorithm with existing algorithm. The obtained results show that the proposed algorithm has superior performance than the existing algorithm. Conclusion: The present work optimizes the position of components using RSA algorithm. RSA returns the lower number of required wireless routers/ONUs, lesser TCD, increased AONUC, fast convergence rate, lesser execution run time than WSSA algorithm. The outcome of the paper highlights the importance of the proposed work in network planning and component deployment in FiWi access network.