scholarly journals Distributed Optimal Random Access Scheme for Energy Harvesting Devices in Satellite Communication Networks

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 99
Author(s):  
Pengxu Li ◽  
Gaofeng Cui ◽  
Weidong Wang
Keyword(s):  
Energy Harvesting ◽  
Communication Networks ◽  
Satellite Communication ◽  
Negative Impact ◽  
Low Cost ◽  
Random Access ◽  
Optimal Solution ◽  
Wireless Channel ◽  
Communication Overhead ◽  
Iteration Algorithm

This paper considers satellite communication networks where each satellite terminal is equipped with energy harvesting (EH) devices to supply energy continuously, and randomly transmits bursty packets to a geostationary satellite over a shared wireless channel. Packet replicas combined with a successive iteration cancellation scheme can reduce the negative impact of packet collisions but consume more energy. Hence, appropriate energy management policies are required to mitigate the adverse effect of energy outages. Although centralized access schemes can provide better performance on the networks’ throughput, they expend extra signallings to allocate the resources, which leads to non-negligible communication latencies, especially for the satellite communication networks. In order to reduce the communication overhead and delay, a distributed random access (RA) scheme considering the energy constraints is studied. Each EH satellite terminal (EH-ST) decides whether to transmit the packet and how many replicas are transmitted according to its local energy and EH rates to maximize the average long-term network throughput. Owing to the nonconvexity of this problem, we adopted a game theoretic method to approximate the optimal solution. By forcing all the EH-STs to employ the same policy, we characterized and proved the existence and uniqueness of the symmetric Nash equilibrium (NE) of the game. Moreover, an efficient algorithm is proposed to calculate the symmetric NE by combining a policy iteration algorithm and the bisection method. The performance of the proposed RA scheme was investigated via numerous simulations. Simulation results showed that the proposed RA scheme is applicable to the EH devices in the future low-cost interactive satellite communication system.

scholarly journals DAIRY PRODUCTIVITY ACCOUNTING AUTOMATIC DEVICE BASED ON RFID AND LORA TECHNOLOGIES

2021 ◽  
Author(s):  
S.B.Baiguanysh A.B. Mirmanov,O.V. Stukach,S.А.Isabekova
Keyword(s):  
Communication Networks ◽  
Milk Yield ◽  
Data Transfer ◽  
Negative Impact ◽  
Dairy Farm ◽  
Automatic Device ◽  
Wireless Channel ◽  
Rfid Tag ◽  
Digital Monitoring ◽  
Milking Machine

Recent years have been marked by the development of dairy farming in Kazakhstan. The number of small farms is growing, but their equipment with modern milking machines remains at a low level. Due to the lack of total control over livestock, their productivity is decreasing. In addition, poor coverage of communication networks has a negative impact on the introduction of IoT technologies. However, the emergence of energy-efficient long- and short-range networks allows the development of devices for remote digital monitoring of certain livestock production parameters, in this case, associated with milk yield. The developed device is implemented on accessory board for Arduino Mega, and includes milk meter on the reed switch, LF RFID tag reader, RFM95W module for data transfer via LoRa protocol and controller based on Atmega 2560. The device is installed on a mobile milking machine and keeps track of milk productivity of each milking cow individually. The device has been tested in laboratory conditions and on a dairy farm. The test results did not reveal any discrepancies in the milk yield automatically obtained via the LoRa wireless channel and the milk volumes physically measured by the beaker.

scholarly journals Towards a Glass New World: The Role of Ion-Exchange in Modern Technology

2021 ◽  
Vol 11 (10) ◽  
pp. 4610
Author(s):  
Simone Berneschi ◽  
Giancarlo C. Righini ◽  
Stefano Pelli
Keyword(s):  
Ion Exchange ◽  
Communication Networks ◽  
High Speed ◽  
High Performance ◽  
Low Cost ◽  
Modern Technology ◽  
Historical Background ◽  
Wide Range ◽  
Happy Marriage

Glasses, in their different forms and compositions, have special properties that are not found in other materials. The combination of transparency and hardness at room temperature, combined with a suitable mechanical strength and excellent chemical durability, makes this material indispensable for many applications in different technological fields (as, for instance, the optical fibres which constitute the physical carrier for high-speed communication networks as well as the transducer for a wide range of high-performance sensors). For its part, ion-exchange from molten salts is a well-established, low-cost technology capable of modifying the chemical-physical properties of glass. The synergy between ion-exchange and glass has always been a happy marriage, from its ancient historical background for the realisation of wonderful artefacts, to the discovery of novel and fascinating solutions for modern technology (e.g., integrated optics). Getting inspiration from some hot topics related to the application context of this technique, the goal of this critical review is to show how ion-exchange in glass, far from being an obsolete process, can still have an important impact in everyday life, both at a merely commercial level as well as at that of frontier research.

Simulation and Design of a Silicon Nanowire based Phase Change Memory Cell

2012 ◽  
Vol 1431 ◽  
Author(s):  
Ramin Banan Sadeghian ◽  
Yusuf Leblebici ◽  
Ali Shakouri
Keyword(s):  
Phase Change ◽  
High Speed ◽  
Low Cost ◽  
Silicon Nanowire ◽  
Phase Change Memory ◽  
Random Access ◽  
Memory Cell ◽  
Oxide Thickness ◽  
Nanowire Diameter ◽  
Change Memory

ABSTRACTIn this work we present preliminary calculations and simulations to demonstrate feasibility of programming a nanoscale Phase Change Random Access Memory (PCRAM) cell by means of a silicon nanowire ballistic transistor (SNWBT). Memory cells based on ballistic transistors bear the advantage of having a small size and high-speed operation with low power requirements. A one-dimensional MOSFET model (FETToy) was used to estimate the output current of the nanowire as a function of its diameter. The gate oxide thickness was 1.5 nm, and the Fermi level at source was set to -0.32 eV. For the case of VDS = VGS = 1 V, when the nanowire diameter was increased from 1 to 60 nm, the output power density dropped from 109 to 106 W cm-2 , while the current increased from 20 to 90 μA. Finite element electro-thermal analysis were carried out on a segmented cylindrical phase-change memory cell made of Ge2Sb2Te5 (GST) chalcogenide, connected in series to the SNWBT. The diameter of the combined device, d, and the aspect ratio of the GST region were selected so as to achieve optimum heating of the GST. With the assumption that the bulk thermal conductivity of GST does not change significantly at the nanoscale, it was shown that for d = 24 nm, a ‘reset’ programming current of ID = 80 μA can heat the GST up to its melting point. The results presented herein can help in the design of low cost, high speed, and radiation tolerant nanoscale PCRAM devices.

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