scholarly journals An Adaptive Time-Spread Multiple-Access Policy for Wireless Sensor Networks

2007 ◽  
Vol 2007 (1) ◽  
Author(s):  
Konstantinos Oikonomou ◽  
Ioannis Stavrakakis
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Multiple Access ◽  
Wireless Sensor ◽  
Access Policy ◽  
Adaptive Time ◽  
Time Spread

scholarly journals Energy-Efficient and Fast MAC Protocol in UAV-Aided Wireless Sensor Networks for Time-Critical Applications

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2635 ◽  
Author(s):  
Sabitri Poudel ◽  
Sangman Moh
Keyword(s):  
Wireless Sensor Networks ◽  
Energy Consumption ◽  
Sensor Networks ◽  
Energy Efficient ◽  
Multiple Access ◽  
Mac Protocol ◽  
Mac Protocols ◽  
Wireless Sensor ◽  
Sensing Applications ◽  
Time Critical

Unmanned aerial vehicle (UAV)-aided wireless sensor networks (UWSNs) can be effectively used for time-critical sensing applications. UAVs can be used to collect the sensed data from sensors and transfer them to a base station. The real-time transfer of data is highly desired in the time-critical applications. However, the medium access control (MAC) protocols designed for UWSNs so far are primarily focused on the efficient use of UAVs to collect data in the sensing areas. In this paper, we propose an energy-efficient and fast MAC (EF-MAC) protocol in UWSNs for time-critical sensing applications. EF-MAC adopts carrier sense multiple access (CSMA) for the registration of sensor nodes with a UAV and time division multiple access (TDMA) with variable slot time for the transmission of collected data. The UAV is equipped with two transceivers to minimize both energy consumption and delay in air-to-ground communication. The energy consumption and delay are formally analyzed and the performance of EF-MAC is evaluated via extensive simulation. The simulation results show that the proposed EF-MAC outperforms the conventional MAC protocols in terms of energy efficiency and communication delay.

scholarly journals Distributed parameter estimation in wireless sensor networks in the presence of fading channels and unknown noise variance

2018 ◽  
Vol 14 (9) ◽  
pp. 155014771880330
Author(s):  
Shoujun Liu ◽  
Kezhong Liu ◽  
Jie Ma ◽  
Wei Chen
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Fading Channels ◽  
Expectation Maximization ◽  
Multiple Access ◽  
Expectation Maximization Algorithm ◽  
Wireless Sensor ◽  
Fusion Center ◽  
Noise Variance ◽  
Access Scheme

Parameter estimation is one of the most important research areas in wireless sensor networks. In this study, we consider the problem of estimating a deterministic parameter over fading channels with unknown noise variance. Owing to the bandwidth constraints in wireless sensor networks, sensor observations are quantized and subsequently transmitted to the fusion center. Two types of communication channels are considered, namely, parallel-access channels and multiple-access channels. Based on the knowledge of channel statistics, the power of the received signals at the fusion center can be described by the mode of the exponential mixture distribution. The expectation maximization algorithm is used to determine maximum likelihood solutions for this mixture model. A new estimator based on the expectation maximization algorithm is subsequently proposed. Simulation results show that this estimator exhibits superior performance compared to the method of moments estimator in both parallel- and multiple-access schemes. In addition, we determine that the parallel-access scheme outperforms the multiple-access scheme when the noise variance is small and it loses its superiority when the noise variance is large.

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