A. Harun

Signal propagation in aquaculture environment for wireless sensor network applications

This paper presents results of signal propagation studies for wireless sensor network planning in aquaculture environment for water quality and changes in water characteristics monitoring. Some water pollutants can cause widespread damage to marine life within a very short time period and thus wireless sensor network reliability is more critical than in crop farming. This paper shows that network coverage models and assumptions over land do not readily apply in tropical aquaculture environment where high temperatures are experienced during the day. More speci¯cally, due to high humidity caused by evaporation, network coverage at 15 cm antenna height is better than at 5m antenna heights due to the presence of a super-refraction (ducting) layer. For a 69m link, the di®erence between the signal strength measured over several days is more than 7dBm except under anomaly conditions. In this environment, the two-ray model has been found to provide high accuracy for signal propagation over water where there are no objects in close proximity to the propagation path. However, with vegetation in close proximity, accurate signal variation predication must consider contributions from scattered and diffused components, taking into account frequency selective fading characteristics to represent the temporal and spatial signal variations.

Signal Propagation Analysis for Low Data Rate Wireless Sensor Network Applications in Sport Grounds and on Roads

This paper presents results of a study to characterise wire-less point-to-point channel for wireless sensor networks applications in sport hard court arenas, grass fields and on roads. Antenna height and orientation effects on coverage are also studied and results show that for omni-directional patch antenna, node range is reduced by a factor of 2 when the antenna orientation is changed from vertical to horizontal. The maximum range for a wireless node on a hard court sport arena has been determined to be 70m for 0dBm transmission but this reduces to 60m on a road surface and to 50m on a grass field. For horizontal antenna orientation the range on the road is longer than on the sport court which shows that scattered signal components from the rougher road surface combine to extend the communication range. The channels investigated showed that packet error ratio (PER) is dominated by large-scale, rather than small-scale, channel fading with an abrupt transition from low PER to 100% PER. Results also show that large-scale received signal power can be modelled with a 2nd order log-distance polynomial equation on the sport court and road, but a 1st order model is sufficient for the grass field. Small-scale signal variations have been found to have a Rice distribution for signal to noise ratio levels greater than 10 dB but the Rice K-factor exhibits significant variations at short distances which can be attributed to the influence of strong ground reflections.

Comparative Performance Analysis of Wireless RSSI in Wireless Sensor Networks Motes in Tropical Mixed-crop Precision Farm

To provide reliable and adequate network coverage whilst minimizing the cost of wireless sensor network (WSN) deployments, detailed knowledge of wireless signal propagation within the specific environments is required. There are many WSN devices on the market that have been developed using proprietary systems and therefore have different performances, although implementing similar standards. This paper presents a comparative performance measurement and analysis of three types of WSN devices evaluated for application in a mixed-crop farm. The results show that the Xbee-PRO maintains very strong RSSI values in open field measurements that are sometime 15 dBm higher than those obtained from the IRIS and Microchip motes. Overall, two important factors that influence WSN node performances are antenna height and the type of antenna used. Whip omni-directional antenna has been shown to double the range of the WSN node compared to a patch antenna. Results also show that the log-distance propagation model is a more flexible model that can be used to model a variety of channels, although it lacks standard global parameter values.

Modelling indoor propagation for WSN deployment in smart building

This paper models the signal strength measurements at 2.4 GHz in indoor environment. The received signal strength indicator (RSSI) measurement is used to investigate the wireless network coverage in a real office environment where obstacles such as furniture are present. From this experiment, a mapping is created to determine the suitable positions for a short range sensor nodes deployment for sensing humidity, temperature, human movement, etc. The purpose is to evaluate the suitable area for WSN deployments using RF signal and to minimize the number of sensor nodes required for data gathering and monitoring applications. The result shows that through adequate planning of WSN nodes, good radio coverage and efficient monitoring can be achieved for greener building.

Modeling and Simulation of WSNs for Agriculture Applications Using Dynamic Transmit Power Control Algorithm

Simulation platforms have become important tools in the design and evaluating of protocols for Wireless Sensor Networks. Thus the use of realistic models in simulation is important for the development of protocols. However, most of the reported studies based on simulations tend to use simple or non-realistic parameters and assumptions. This paper proposes a transmit power control algorithm with a realistic radio energy model based on different propagation models to mimic different deployment scenarios. Results show that the implementation of transmit power control extends the network lifetime by 5.3% when free space path loss model is used. However, a greater efficiency of 8.7% is achieved when the network is assumed to be deployed in the presence of vegetation using Weissbergers vegetation attenuation model.

Data Mining on Climatic Factors for Harumanis Mango Yield Prediction

Yield Prediction is an essential task to be achieved in order to implement effective forward marketing. Forward marketing is a contract that will be signed between supplier and client based on the amount of delivery and the price of delivery in future. To be able to sign such a contract the supplier should be very confident that the yield could be achieved. The yield sustainability is a challenging process in agriculture. Mango cultivar Harumanis is one of the best table tropical fruit due to its aroma and sweetness. Despite its overwhelming local demand in Malaysia and also internationally, the fruit supply never meets the demand. The flowering phase is identified as an important stage as plant reproductive physiology. Currently, Harumanis mango flowering only happens once a year that restricts the yield. In this paper, data mining is used to quantify the climatic effects on Harumanis mango yield to enable yield prediction.

Low noise figure 2.4 GHz down conversion CMOS mixer for wireless sensor network application

This work proposed a low noise figure 2.4 GHz down-conversion CMOS mixer for wireless sensor network (WSN) application using 0.13-μm Silterra technology. The proposed down-conversion mixer converts a high radio frequency (RF) signal from 2.4 GHz to an intermediate frequency (IF) of 100 MHz through the use of a local oscillator signal (LO) of 2.3 GHz. The proposed mixer employs a double balance Gilbert-cell topology with integrated input matching at the input stage and a low pass filter at the IF stage. The simulation results indicate that the proposed mixer obtains lower noise figure (NF) of 5.21 dB with an input third-order intercept point (IIP3) of 0 dB. Furthermore, the conversion gain (CG) of 8.6 dB is achieved with the power consumption of 1.57 mW at 1.8 V supply voltage.

Shalala Cipher, a New Implementation of Vigenere Cipher for Wireless Sensor Node Security.

Cryptography is a science that deals on the method of converting plaintext into cipher text, usually with the help of encryption keys and encryption algorithm. Current standard implementation of cryptography is proved to require high resource in memory which is not suitable to be implemented in low memory embedded system, thus a lightweight cryptography are required. Vigenere cipher is one of the encryption algorithms that was easy to implement and comprehand, which can be used to provide confidentiality from the third party. Vigenere cipher is a polyalphabetic Ceaser cipher, which means it shifting the character in plaintext to become character of mod of its key character. Even thou Vigenere cipher are a classical cipher that doing its cipher using character compared to modern cipher that doing its cipher using bits and byte, it still can be implemented in modern computer by representing its character based on ASCII Table. Furthermore, because of this, its character can be extended to contain all alphabet and special character in the ASCII Table, thus allowing it to encrypt every character that can be represented using ASCII Table. Originally the resilience of Vigenere cipher is based on two factors: (1) the length of its key, and (2) the randomness of character in its key. Even though increasing the length and the used random character provide a great resilience, it takes away the fun of using dictionary word to encrypt the plaintext. To overcome that, this paper, proposing a method of implementing a Pseudorandom Path that change the flow of mod use by the Vigenere Cipher to encrypt and decrypt either positive mod or negative mod. Usually Vigenere Cipher use positive mode to encrypt, while negative mod to decrypt, however this paper propose a method to combine both mod during encryption or decryption with the supervision from the Pseudorandom Path. This method of implementation and its result were discussed in this paper and named as Shalala Cryptography. The results were compared between using original resilience and a Shalala Cryptography method. The resource requirement to implement this algorithm using C++ language is also shown, which shows a lightweight cryptography scheme in term of RAM consumption and fast processed time, which are suitable to be used in WSN or IoT environment.

S-band multi-wavelength ring cavity Brillouin Raman fiber laser exploiting different FBG reflectivity

In this paper, we demonstrated a ring cavity multiwavelength Brillouin Raman fiber laser exploiting different Fiber Bragg grating reflectivity. The 10 km length of single mode fiber are used as gain medium that has the capability to generate Stimulated Brillouin Scattering and Stimulated Raman Scattering effect. The ring cavity multi-wavelength Brillouin Raman fiber laser is operated in S-band region which is from1460nm to 1530nm. The laser input Brillouin pump power is varied from 2dBm to 20dBm. Meanwhile, Raman pump wavelength is varied from 1460nm to 1530nm and the Raman power is injected at 16 dBm, respectively. The output bidirectional coupler ratio is varied at 50%, 60%, 70%, 80% and 90%. Meanwhile, the fiber Bragg grating reflectivity value from 0.4 to 0.99 are tested differently to obtain the best output. As a result, the high number Brillouin Stokes signal of 7 are generated at 80% output coupling ratio, fiber Bragg grating reflectivity of 0.9 and Brillouin pump power of 12dBm, respectively.

Size efficiency for sensor node with embedded processing unit

Due to increase embedded computer technology, it has been increasingly used in many research field including area of Wireless Sensor Network (WSN). The principle of embedded technology is flexible but low operational cost. Nowadays, embedded system technology is chosen because it offers brilliant solutions from many possibilities combined with its nature of economic and feasibility of advanced. This paper presents the way to minimize storage needed for WSN that deals with voice signal. Since the embedded computer is used as aggregator node and able to do extract voice signal using feature extraction, results show that size needed for storing and transmitting of high quality voice signal will significantly decrease after doing feature extraction.