scholarly journals Slotted ALOHA on LoRaWAN-Design, Analysis, and Deployment

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 838 ◽  
Author(s):  
Tommaso Polonelli ◽  
Davide Brunelli ◽  
Achille Marzocchi ◽  
Luca Benini
Keyword(s):  
Single Channel ◽  
Low Cost ◽  
Network Throughput ◽  
Sensor Nodes ◽  
Slotted Aloha ◽  
Medium Access ◽  
Packet Collision ◽  
Sensing Applications ◽  
Hardware Platforms ◽  
The Impact

LoRaWAN is one of the most promising standards for long-range sensing applications. However, the high number of end devices expected in at-scale deployment, combined with the absence of an effective synchronization scheme, challenge the scalability of this standard. In this paper, we present an approach to increase network throughput through a Slotted-ALOHA overlay on LoRaWAN networks. To increase the single channel capacity, we propose to regulate the communication of LoRaWAN networks using a Slotted-ALOHA variant on the top of the Pure-ALOHA approach used by the standard; thus, no modification in pre-existing libraries is necessary. Our method is based on an innovative synchronization service that is suitable for low-cost wireless sensor nodes. We modelled the LoRaWAN channel with extensive measurement on hardware platforms, and we quantified the impact of tuning parameters on physical and medium access control layers, as well as the packet collision rate. Results show that Slotted-ALOHA supported by our synchronization service significantly improves the performance of traditional LoRaWAN networks regarding packet loss rate and network throughput.

Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

2020 ◽  
Vol 90 (3) ◽  
pp. 30502
Author(s):  
Alessandro Fantoni ◽  
João Costa ◽  
Paulo Lourenço ◽  
Manuela Vieira
Keyword(s):  
Amorphous Silicon ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Deposition Process ◽  
Large Area ◽  
Sidewall Roughness ◽  
Sensing Applications ◽  
Fabrication Defects ◽  
The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

scholarly journals On-Body Characterization of Planar Differential Antennas for Multiple, Wide, and Narrow Bands

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Luigi Vallozzi ◽  
Domenico Pepe ◽  
Thijs Castel ◽  
Hendrik Rogier ◽  
Domenico Zito
Keyword(s):  
Human Body ◽  
Ad Hoc ◽  
Low Cost ◽  
Experimental Tests ◽  
Body Measurements ◽  
Antenna Performance ◽  
Sensing Applications ◽  
The Impact ◽  
Narrow Bands

This paper reports the results of the on-body experimental tests of a set of four planar differential antennas, originated by design variations of radiating elements with the same shape and characterized by the potential for covering wide and narrow bands. All the antenna designs have been implemented on low-cost FR4 substrate and characterized experimentally through on-body measurements. The results show the impact of the proximity to the human body on antenna performance and the opportunities in terms of potential coverage of wide and narrow bands for future ad hoc designs and implementations through wearable substrates targeting on-body and off-body communication and sensing applications.

An Improved Frequency Agility Mechanism for SimpliciTI Protocol

2014 ◽  
Vol 543-547 ◽  
pp. 3486-3489 ◽  
Author(s):  
Jun Qiang Wang ◽  
Jing Wu
Keyword(s):  
Low Power ◽  
Low Cost ◽  
Sensor Nodes ◽  
Channel Migration ◽  
Development Cycle ◽  
Short Development Cycle ◽  
Specific Frequency ◽  
Simulation Results ◽  
The Impact ◽  
Better Than

The rapid growth of application for low-cost, low power sensor nodes based on WSN brings its own challenges. SimpliciTI is a simple low-power RF network protocol that with open Source, flexibility, and low-cost, short development cycle and so on. Aiming at the blindness problem of channel migration when this specific frequency is noisy, We presented PSCP-FA(periodic synchronism and channel prediction Frequency agility) which accomplish the channel agility predictable. Furthermore, we evaluated the impact of energy of efficiency compared with S-MAC and FA. Our simulation results show that PSCP-FA performs better than S-MAC and FA.

scholarly journals Modeling Slotted Aloha as a Stochastic Game with Random Discrete Power Selection Algorithms

2009 ◽  
Vol 2009 ◽  
pp. 1-28 ◽  
Author(s):  
Rachid El-Azouzi ◽  
Essaid Sabir ◽  
Tania Jiménez ◽  
El-Houssine Bouyakhf
Keyword(s):  
Stochastic Game ◽  
Game Problem ◽  
Base Station ◽  
Noncooperative Game ◽  
Slotted Aloha ◽  
Medium Access ◽  
Cooperative Team ◽  
The Individual ◽  
Selection Algorithms ◽  
The Impact

We consider the uplink case of a cellular system where bufferless mobiles transmit over a common channel to a base station, using the slotted aloha medium access protocol. We study the performance of this system under several power differentiation schemes. Indeed, we consider a random set of selectable transmission powers and further study the impact of priorities given either to new arrival packets or to the backlogged ones. Later, we address a general capture model where a mobile transmits successfully a packet if its instantaneous SINR (signal to interferences plus noise ratio) is lager than some fixed threshold. Under this capture model, we analyze both the cooperative team in which a common goal is jointly optimized as well as the noncooperative game problem where mobiles reach to optimize their own objectives. Furthermore, we derive the throughput and the expected delay and use them as the objectives to optimize and provide a stability analysis as alternative study. Exhaustive performance evaluations were carried out, we show that schemes with power differentiation improve significantly the individual as well as global performances, and could eliminate in some cases the bi-stable nature of slotted aloha.

scholarly journals Sorting on Single-Channel Wireless Sensor Networks

2003 ◽  
Vol 14 (03) ◽  
pp. 391-403 ◽  
Author(s):  
Jacir Luiz Bordim ◽  
Koji Nakano ◽  
Hong Shen
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Single Channel ◽  
Low Cost ◽  
Physical World ◽  
Base Station ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Radio Communications ◽  
The Cost

A Wireless Sensor Network (WSN) is a distributed system consisting of a large number of wireless sensing devices and a base station. Due to their compactness and low-cost, sensor networks can be distributed at a fraction of the cost of conventional wired sensors and actuator systems. The physical world generates an unlimited amount of data that can be observed and monitored. Hence, designing protocols to coordinate WSNs with hundreds, or even thousands, of sensors will face many challenges. In this work we focus on the design of protocols that enable the sensor nodes to coordinate among themselves to achieve a larger task. From this standpoint, we present a sorting protocol for wireless sensor networks. We show that in a WSN consisting of n sensor nodes, where each sensor stores an element and has a fixed transmission range r. sorting can be performed in [Formula: see text] time slots when [Formula: see text]. We also reason that future applications of wireless sensor networks are very likely to employ short-range radio communications (i.e., r less than 100 meters). If this is the case, the time complexity of our sorting protocol is optimal.

scholarly journals Collision-aware distributed detection with population-splitting algorithms

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Seksan Laitrakun
Keyword(s):  
Single Channel ◽  
Random Access ◽  
Transmission Probability ◽  
Distributed Detection ◽  
Sensor Nodes ◽  
Final Decision ◽  
Slotted Aloha ◽  
Splitting Algorithm ◽  
Access Protocol ◽  
Random Access Protocol

AbstractWe consider the design of distributed detection algorithms for single-hop, single-channel wireless sensor networks in which sensor nodes send their local decisions to a fusion center (FC) by using a random access protocol. There is also limited time to collect local decisions before a final decision must be made. We thus propose and analyze a modified random access protocol in which the FC combines slotted ALOHA with a population-splitting algorithm called population-splitting-based random access (PSRA) and collision-aware distributed detection according to an estimate-then-fuse approach. Under the PSRA, only sensor nodes whose observations fall in a particular range of reliability will send their decisions in a specific frame by using slotted ALOHA. At the end of the collection time, the FC applies the collision-aware distributed detection to make a final decision. Here, the FC will first observe the state of each time slot—idle, successful, collision—in each frame, use this information to estimate the number of sensor nodes participating in each frame, and, then, compute a final decision using a population-based fusion rule. An approximation of the optimal transmission probability of the slotted ALOHA is determined to minimize the probability of error. Numerical results show that, unlike slotted-ALOHA-based data networks, the transmission probability maximizing the number of successful time slots does not optimize the performance of the proposed distributed detection. Instead, the proposed distributed detection performs best with a transmission probability that induces many collisions.

Advancing dairy farming profitability through research

2001 ◽  
pp. 17-22
Author(s):  
J.R. Caradus ◽  
D.A. Clark
Keyword(s):  
Research And Development ◽  
Dairy Cow ◽  
Low Cost ◽  
Pasture Management ◽  
Nitrogen Fertiliser ◽  
Grass Endophyte ◽  
Forage Species ◽  
Development Outcomes ◽  
Dairy Cow Nutrition ◽  
The Impact

The New Zealand dairy industry recognises that to remain competitive it must continue to invest in research and development. Outcomes from research have ensured year-round provision of low-cost feed from pasture while improving productivity. Some of these advances, discussed in this paper, include the use of white clover in pasture, understanding the impacts of grass endophyte, improved dairy cow nutrition, the use of alternative forage species and nitrogen fertiliser to improve productivity, demonstration of the impact of days-in-milk on profitability, and the use of feed budgeting and appropriate pasture management. Keywords: dairy, profitability, research and development

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