Successful Deployment of a Wireless Sensor Network for Precision Agriculture in Malawi

This paper demonstrates how an irrigation management system (IMS) can practically be implemented by deploying a wireless sensor network (WSN). Specifically, the paper describes an IMS which was set up in Manja township, city of Blantyre. Deployment of IMS in rural areas of developing countries like Malawi is a challenge as grid power is scarce. For the system to be self-sustained in terms of power, the study used solar photovoltaic and rechargeable batteries to power all electrical devices. The system incorporated a remote monitoring mechanism through a General Packet Radio Service modem to report soil temperature, soil moisture, WSN link performance, and photovoltaic power levels. Irrigation valves were activated to water the field. Preliminary results in this study have revealed a number of engineering weaknesses of deploying such a system. Nevertheless, the paper has highlighted areas of improvement to develop a robust, fully automated, solar-powered, and low-cost IMS to suit the socioeconomic conditions of small scale farmers in developing countries

Successful Deployment of a Wireless Sensor Network for Precision Agriculture in Malawi

This paper demonstrates how an Irrigation Management System (IMS) can practically be implemented by successfully deploying a Wireless Sensor Network (WSN). Specifically, the paper describes an IMS which was set up in Manja Township, City of Blantyre based on an advanced irrigation scheduling technique. Since the system had to be self-sustained in terms of power, which is a challenge for deployment in rural areas of developing countries like Malawi where grid power supply is scarce, we used solar Photovoltaic (PV) and rechargeable batteries to power all electrical devices in this system. The system incorporated a remote monitoring mechanism through a General Packet Radio Service (GPRS) modem to report soil temperature, soil moisture, WSN link performance and PV power levels. Irrigation valves were activated to water the field. Our preliminary results have revealed engineering weakness of deploying such a system. Nevertheless, the paper shows that it is possible to develop a robust, fully-automated, solar powered, and low cost IMS to suit the socio-economic conditions of small scale farmers in developing countries

Mobile telecommunication CDMA power control for S-UMTS.

Since under the UMTS framework, the development of S-UMTS follows that of T-UMTS with the ultimate aim of achieving close integration between S-UMTS and T-UMTS air-interface designs, closed-loop transmit power control (TPC) remains a physical-layer procedure option for enhancing the performance of S-UMTS. In S-UMTS, however, closed-loop TPC should be modified to take into account large TPC command delays due to propagation. In this thesis, we study strength-based closed-loop TPC schemes for S-UMTS in order to develop TPC schemes that mitigate the effects of TPC command delays due to propagation. The study focuses on link-level analysis of the SW-CDMA based air-interface for the S-UMTS. Firstly, a mathematical model describing the dynamic behaviour of the closed-loop TPC has been developed as a stochastic difference equation, where the effects of TPC command delays in the presence of random disturbance are modelled as a random walk process, with a probability density function (pdf) of the TPC error process as its solution. The pdf is obtained by solving a corresponding Fokker-Planck equation whose derivate moments are obtained via statistical linearisation. The results show that although it is widely accepted that the TPC error process is lognormally distributed, the nonlinearity due to the fixed TPC step-size may flatten the pdf when the TPC delays and step-size are large. Secondly, predictive TPC schemes that mitigate the effects of delays and adaptive techniques that improve upon the performance offered by standard algorithms have been proposed and evaluated through Monte-Carlo simulations. In particular, a simple LMS algorithm has been chosen as an appropriate tracking algorithm for the predictive TPC schemes in S-UMTS, and in order to improve upon the performance offered by the standard LMS algorithm, a filter-shaped LMS algorithm for predictive TPC has been proposed for S-UMTS. Furthermore, the simulation results have shown that step-size adaptation, when complemented with power prediction, significantly improves the performance of the closed-loop TPC schemes even in the presence of TPC command delays. Finally, numerical results have shown that the accuracy of TPC has significant influence on the capacity. For example, a modest improvement in the standard deviation of the TPC error from 1.5 dB to 1.0 dB may yield a capacity improvement from 21 to 32 users per spotbeam: a relative gain of approximately 50%. Therefore, closed-loop TPC remains an important radio resource management procedure for mitigating slow-fading due to shadowing in S-UMTS, power prediction mitigates the effects of TPC command delays, and more accurate TPC schemes are necessary to realise high capacity S-UMTS networks

Mobile telecommunication CDMA power control for S-UMTS

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Design of outdoor wireless networks using computer simulation

In this paper, we design a pilot outdoor wireless network based on IEEE 802.11b standard for HealthCare Applications through computer simulation. The purpose is to demonstrate the use of computer simulation in designing outdoor wireless networks. We use a free software tool called Radio Mobile and freely available geographical elevation data downloaded from NASA to determine the radio frequency (RF) coverage of a wireless networking base-station and radio link performance. Furthermore, we demonstrate the flexibility of computer simulation in assessing design alternatives

Remote monitoring for wireless sensor based irrigation system in Malawi

In the recent years there has been an increase in the application of Wireless Sensor Networks (WSNs) in agriculture, specifically aiding automatic application of water, chemicals and fertilizers to the field. Since WSNs are still under development stage, they are at times unreliable, power hungry, fragile and they easily lose communication. Intrinsically, any irrigation system based on WSNs requires close monitoring to guard against any horrendous mishaps. However, monitoring such an irrigation system which, usually, is located at a rural site can be expensive and time consuming. In this paper we developed an efficient, cost-effective and real-time wireless based remote monitoring mechanism for a WSN based Irrigation system situated in Manja Township within Blantyre city. The system archives data that include the soil moisture potential, link performance, electrical power levels, and valve status and subsequently sends the information as a text message over a cellular network to a remote monitoring site located at the Malawi Polytechnic. The remote station has a broadband wireless dongle which is interfaced to a MYSQL database via an open source FrontlineSMS. The information is graphically published on a web browser with the help of a PHP script. Preliminary results demonstrate that a WSN based irrigation system can be monitored remotely at a low cost and in real time

Experimental performance analysis of wireless links for healthcare applications

Wireless networking is currently being deployed for various applications. However, the application of wireless networking in healthcare remains a challenge mainly because of security and reliability concerns. This paper presents experimental results of performance analysis of a wireless network for healthcare application in the City of Blantyre. The results show that the use of wireless networking in healthcare application will be limited by packet loss, delay and jitter when the number of hops involved in the transmission of information is large. Nevertheless, deployment of wireless networking for healthcare applications is viable when the number of hops a packet has to transverse is small