Performance Study of Wireless Sensor Networks in Aquaculture Environments

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Performance Study of Wireless Sensor Networks in Aquaculture Environments

by

Mohd Azudin bin Mohd Arif (0730210166)

A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science (Computer Engineering)

School of Computer and Communication Engineering UNIVERSITI MALAYSIA PERLIS

2014

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UNIVERSITI MALAYSIA PERLIS

NOTES : * If the thesis is CONFIDENTIAL or RESTRICTED, please attach with the letter from the organization with period and reasons for confidentially or restriction.

DECLARATION OF THESIS

Author’s full name : Mohd Azudin Bin Mohd Arif Date of birth : 16 February 1977

Title : Performance Study of Wireless Sensor Networks in Aquaculture Environments.

Academic Session : 2007 / 2014

I hereby declare that the thesis becomes the property of Universiti Malaysia Perlis (UniMAP) and to be placed at the library of UniMAP. This thesis is classified as :

CONFIDENTIAL (Contains confidential information under the Official Secret Act 1972)*

RESTRICTED (Contains restricted information as specified by the organization where research was done)*

OPEN ACCESS I agree that my thesis is to be made immediately available as hard copy or on-line open access (full text)

I, the author, give permission to the UniMAP to reproduce this thesis in whole or in part for the purpose of research or academic exchange only (except during a period of _____ years, if so requested above).

Certified by:

_________________________ _________________________________

SIGNATURE SIGNATURE OF SUPERVISOR

______770216-14-5411_______ _Prof. Dr. Ali Yeon Bin Md Shakaff_____

(NEW IC NO. / PASSPORT NO.) NAME OF SUPERVISOR

Date :_21 October 2014_____ Date : _21 October 2014_____

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Acknowledgemet

First of all I would like express my gratitude to Allah with the words of Alhamdulillah for the enlighten and guidance that he provide to me until I was able to complete this Master Thesis as required. Thank you goes to my supervisors, Prof. Dr.

Ali Yeon bin Md. Shakaff and Prof. Dr. Mohd Noor bin Ahmad for guiding and sharing their valuable knowledge, experiences and ideas with me. My heartfelt gratitude goes to my beloved parents, Allahyarham Tuan Haji Mohd Arif bin Abu Amin and Puan Hajjah Normah binti Osman for their sacrifices and cares. To my dear wife Asma bint Mat, thank you for your patience and sacrifice on everything that we share together. To my children, Muhammad Salahuddin and Siti Maryam, I love you both. Thank you to anyone who involved in this research especially from Sensor Technology and Applications Cluster Research, CEASTech, UniMAP, UUM and Fisheries Department for their morale support.

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TABLE OF CONTENT

Page Number

CHAPTER 1 INTRODUCTION 1

1.1. Background 1

1.2. Multipath Fading Effect 5

1.3. Problem Statement 6

1.4. Objectives 7

1.5. Scopes 8

1.6. Research Contribution 9

1.7. Outlines 10

CHAPTER 2 LITERATURE REVIEW 12

2.1. WSN Aquaculture Researches 12

2.2. Signal Propagation Researches 16

2.3. Solutions to Reduce Multipath Fading Effect 18

2.4. Taxonomy of Researches 20

CHAPTER 3 RESEARCH METHODOLOGY 23

3.1. Hardware and Protocol 23

3.2. Methods of Experiment 25

3.2.1. General Experimental Setups and Procedures 25

3.3. Methods of Analysis 29

3.3.1. PER 30

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3.3.2. Received Power 30

3.3.2.1. Raw Data 31

3.3.2.2. Average Received Power 31

3.3.3. Standard Deviation 33

3.3.4. Goodness of Fit Test (χ² Test) 33

3.3.4.1. Rice Distribution 34

3.3.4.2. Rayleigh Distribution 37

3.3.5 Rice K (Rice Factor) 39

CHAPTER 4 SIGNAL PROPAGATION CHARACTERISTICS 40

4.1. Introduction 40

4.2. Experimental Setups 41

4.3. Results and Discussions 44

4.3.1. PER 44

4.3.2. Received Power and Standard Deviation 45

4.3.3. χ² Test 48

4.3.4. Rice K 50

4.4. Node Positions and Signal Propagation Characteristics 53

4.5. Analysis Tools 54

4.6. Experimental Summary 55

CHAPTER 5 AQUACULTURE ENVIRONMENT 58

5.1. Method of Experiment 60

5.2. Experiment 1: Indoor Aquaculture Environment (Fish Hatchery) 63

5.2.1. Experimental Setups 65

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5.2.2. Results and Discussions 67

5.2.2.1. Faded Signal Propagation 67

5.2.2.2. Minimum Fading Signal Propagation 71 5.3. Experiment 2: Outdoor Aquaculture Environment (Fish Pond) 75

5.3.1. Experimental Setups 76

5.3.2. Results and Discussions 78

5.3.2.1. Faded Signal Propagation 78

5.3.2.2. Minimum Fading Signal Propagation 81

5.4. Experimental Summary 83

CHAPTER 6 CONCLUSIONS 87

6.1. Research Summary 87

6.2. Research Contribution 89

6.3. Future Work 90

REFERENCES 91

APPENDICES

A List Of Publications 99

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LIST OF FIGURES

Page

1.1. WSN node design. 2

1.2. WSN topology. 3

1.3. Multipath fading effect (Dobkin, 2005) 5

3.1. Microchip PICDEMZ, WSN board. 23

3.2. General experimental setups. 27

3.3. Analysis methods. 29

4.1. Multipurpose court, environment of the outdoor experiment. 41

4.2. The outdoor experiment device setups. 42

4.3. The outdoor experiment WSN board positions. 43 4.4. The outdoor experiment data transmission scenario. 43

4.5. The outdoor raw data analysis result. 46

4.6. The outdoor average received power analysis result. 48

4.7. The outdoor χ² test analysis result. 49

4.8. The outdoor Rice K analysis result. 51

4.9. The outdoor received power curve. 54

5.1. The fish hatchery method of experiment. 60

5.2. African Catfish (Clarias gariepinus), a product of Department Fisheries Malaysia Fish Hatchery at Jitra, Kedah, Malaysia. 63

5.3. The fish hatchery environment. 64

5.4. The fish hatchery source of multipath fading. 64

5.5. The fish hatchery WSN node locations. 65

5.6. The fish hatchery experimental setup. 66

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5.7. The fish hatchery received power analysis for faded signal

propagation. 68

5.8. The fish hatchery χ² test analysis result for faded signal propagation. 69 5.9. The fish hatchery Rice K analysis result for faded signal propagation. 70 5.10. The fish hatchery received power analysis result for minimum fading

signal propagation. 72

5.11. The fish hatchery χ² test analysis result for minimum fading signal

propagation. 73

5.12. The fish hatchery Rice K analysis result for minimum fading signal

propagation. 74

5.13. The fish pond environment. 76

5.14. The fish pond experimental setup. 77

5.15. The fish pond χ² test analysis result for faded signal propagation. 80 5.16. The fish pond χ² analysis result for minimum fading signal

propagation. 83

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LIST OF TABLES

Page 2.1. Taxonomy of WSN Researches for Aquaculture Application and

Signal Propagation Study. 20

4.1. The outdoor PER analysis result. 45

4.2. The outdoor standard deviation analysis result. 47 4.3. The outdoor Rice components analysis result. 52 4.4. The outdoor signal propagation characteristics. 53

4.5. Analysis tools descriptions. 55

5.1. The fish hatchery distance between the base station and the transmitter with horizontal distance, dh of 3.5 m. 67 5.2. The fish hatchery PER analysis result for faded signal propagation. 68 5.3. The fish hatchery standard deviation analysis result for faded signal

propagation. 69

5.4. The fish hatchery Rice distribution components analysis result for

faded signal propagation. 70

5.5. The fish hatchery PER analysis result for minimum fading signal

propagation. 71

5.6. The fish hatchery standard deviation analysis result for minimum

fading signal propagation. 72

5.7. The fish hatchery Rice distribution components analysis result for

minimum fading signal propagation. 74

5.8. The fish pond distance between the base station and the transmitter. 78 5.9. The fish pond PER analysis result for faded signal propagation. 78

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5.10. The fish pond average received power and standard deviation analysis results for faded signal propagation. 79 5.11. The fish pond Rice distribution components analysis result for faded

5.12. The fish pond PER analysis result for minimum fading signal

propagation. 81

5.13. The fish pond standard deviation analysis result for minimum fading

5.14. The fish pond Rice distribution components analysis result for

minimum fading signal propagation. 83

5.15. The fish hatchery summary of analysis results. 84 5.16. The fish pond results overall pond side and analysis tools 85

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LIST OF EQUATIONS

Page

3.1. PER (Packet Error Rate) 30

3.2. Friis transmission formula 31

3.3. Two Ray signal propagation model. 32

3.4. Average received power. 32

3.5. Average received power in dBm. 32

3.6. Standard deviation. 33

3.7. Goodness of fit χ² test. 34

3.8. General Rice distribution Probability Density Function. 35 3.9. 0^th order modified Bessel function of first kind. 35 3.10. Simplified 0^th order modified Bessel function of first kind. 36 3.11. Simplified Rice distribution Probability Density Function. 36 3.12. Maximum likelihood of Rice distribution Probability Density

Function. 36

3.13. Maximum likelihood of Simplified Rice distribution Probability

Density Function. 37

3.14. Voltage calculation with power and resistance relationship. 37 3.15. Rayleigh distribution Probability Density Function. 38 3.16. Rayleigh distribution Probability Density Function with V_rms. 38 3.17. Rayleigh distribution Probability Density Function with power

signals. 38

3.18. Diffuse component of Rayleigh distribution. 38

3.19. Rice Factor, K. 39

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3.20. Rice factor, K in dB. 39 4.1. WSN device signal propagation characteristics. 54

5.1. Pythagoras theorem calculation. 65

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LIST OF ABBREVIATIONS

6LowPAN IPv6 over Low power Wireless Personal Area Networks

ACK Acknowledge

BER Bit Error Rate

CAP Contention Free Period

CRC Cyclic Redundancy Check

CSMA-CA Carrier Sense Multiple Access Collision Avoidance

dBi Decibels-isotropic

dBm Millidecibel

DC Direct Current

DO Dissolved Oxygen

DSP Digital Signal Processing

DSSS Direct Sequence Spread Spectrum

EEPROM Electrical Erasable Programmable Read Only Memory

FFD Full Functional Device

GSM Global System for Mobile Communication GUI Graphical User Interface

IEE Institute of Electrical Engineers

IEEE Institute of Electrical and Electronics Engineers ISM Industrial, Scientific and Medical

K Rice Factor

LOS Line of Sight

LR-WPAN Low Rate Wireless Personal Area Network

MAC Medium Access Control

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MP Monitoring Program

NiMH Nickel Metal Hydride

NLOS Non Line of Sight

NH4+

Ammonium

O-QPSK Offset Quadrature Phase Shift Keying

P2P Point to Point

PAN Personal Area Network

PDF Probability Density Function

PER Packet Error Rate

RF Radio Frequency

RFD Reduced Function Device

RFID Radio Frequency Identification RSSI Received Signal Strength Indicator

SMS Short Messaging System

SPI Serial Peripheral Interface

UHF Ultra High Frequency

USART Universal Synchronous / Asynchronous Receiver / Transmitter VAC Alternating Current Voltage

VDC Direct Current Voltage

VRMS Root Mean Square Voltage

Wifi Wireless Fidelity

WirelessHART Wireless Highway Addressable Remote Transducer WLAN Wireless Local Area Network

WSN Wireless Sensor Networks

χ² Chi square

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Kajian Prestasi Rangkaian Sensor Tanpa Wayar di Dalam Persekitaran Perikanan

ABSTRAK

Kesan multipath fading adalah masalah biasa bagi perambatan isyarat atau gelombang elektromagnet. Bagi sistem Rangkaian Sensor Tanpa Wayar atau WSN (Wireless Sensor Networks), kesan ini mengurangkan prestasi sistem dengan mengakibatkan penolakan paket, kehilangan paket dan memendekkan hayat rangkaian. Kewujudan dan tahap kesan ini bergantung pada keadaan persekitaran sistem komunikasi. Untuk menyelesaikan masalah kesan multipath fading sistem WSN, kajian perambatan isyarat mesti dijalankan di persekitaran di mana sistem akan digunakan. Objektif kajian ini ialah untuk mengkaji perambatan isyarat peranti WSN dan kedudukan fizikal peranti tersebut yang mempengaruhi ciri-ciri perambatan isyarat, untuk mengesahkan peralatan analisis yang sesuai (Kadar Kehilangan Paket, purata kuasa yang diterima, sisihan piawai, ujian χ² kesesuain data dan Rice K) untuk kajian perambatan isyarat, untuk mengkaji perambatan isyarat bagi peranti WSN di tempat perikanan dengan tumpuan kepada isu kesan multipath fading, untuk mengurangkan kesan multipath fading dengan menggunakan kaedah pengawalan masa di antara penghantaran paket dan sebagai kajian kesesuaian sistem WSN di tempat perikanan. Eksperimen pertama telah dijalankan di kawasan luar terbuka (gelanggang sukan). Eksperimen ini dijalankan dengan meletakkan nod-nod pada kedudukan yang berbeza (menegak, mendatar dan rendah) dan pada jarak yang berbeza (10 - 40 m). Hasil kajian ini mendapati kedudukan menegak menunjukkan prestasi terbaik di dalam semua analisa. Lengkungan purata kuasa yang diterima adalah berturutan dan dapat diwakilkan dengan model persamaan polinomial kuasa dua. Daripada persamaan ini, jarak maksimum komunikasi dianggarkan sejauh 70 m sahaja. Eksperimen kedua dijalankan di tempat perikanan tertutup (tempat penetasan ikan). Di tempat ini, kesan multipath fading didapati adalah rendah di mana analisa sisihan piawai mendapati Tanki 3 mempunyai variasi data yang tinggi dan analisa Rice K menunjukkan komponen lurus bagi Tanki 9 adalah tidak berturutan. Setelah menghantar paket dengan 100 ms, kesan ini dapat diminimumkan dengan variasi data bagi Tanki 3 menjadi rendah dan komponen lurus bagi Tanki 12 menjadi berturutan. Eksperimen ketiga telah dijalankan di tempat perikanan terbuka (kolam ikan). Eksperimen ini mendapati kesan multipath fading di tempat ini adalah tinggi dimana terdapat nilai PER(Kadar Ralat Paket) bagi sisi D adalah melebihi 1%.

Selepas menghantar paket pada 50 ms, kesan ini dapat dikurangkan di mana nilai PER berkurangan di bawah nilai 1%. Kajian ini menyimpulkan bahawa kesan multipath fading adalah wujud di tempat perikanan. Dengan menggunakan gabungan peralatan analisis PER, purata kuasa yang diterima, sisihan piawai, ujian χ² dan Rice K mampu menganalisis kesan multipath fading. Kesan ini boleh dikurangkan dengan mengawal selang masa di antara penghantaran data. Kajian ini mendapati sistem WSN boleh digunakan di tempat perikanan.

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Performance Study of Wireless Sensor Networks in Aquaculture Environment ABSTRACT

Multipath fading effect is a common problem of electromagnetic wave or signal propagation. For WSN (Wireless Sensor Networks) system, the effect is able to degrade the system by contributing to the problem of packet rejection, packet loss and shortening the network lifetime. The existence and level of the effect is totally depend on the conditions of the communication system environment. To solve the problem of the effect, a signal propagation study must be conducted in the environment where the system will be implemented. The objectives of this research is to study the signal propagation characteristics of WSN devices and the devices physical position that influence signal propagation characteristics, to verify suitable analysis tools (Packet Error Rate, average received power, standard deviation, goodness of fit χ² test and Rice K ) for signal propagation study, to study the signal propagation of WSN devices in aquaculture environments with focusing on multipath fading effect issue, to minimise multipath fading effect by using the method of controlling time interval between packets transmission and to study the feasibility of WSN system to be implemented in aquaculture environments. The first experiment was conducted at an open outdoor area (sports arena). The experiment was conducted by placing the nodes in different positions (vertical, horizontal and low) at different distances (10 – 40 m) between nodes. The result shows the vertical position has the best performance in all analysis.

The average received power curve is monotonic and it can be modeled by second order of polynomial equation. From this equation, the maximum range of communication is estimated at 70 m. The second experiment was conducted at an indoor aquaculture environment (fish hatchery). In this environment, the multipath fading effect is found at low level where the standard deviation analysis shows Tank 3 has high variation of data and the Rice K analysis shows the direct component of Tank 9 is not monotone. After sending packets at 100 ms, the effect has been minimised with the variation of data is become low for Tank 3 and the direct component of Tank 12 is become monotone. The third experiment was conducted at an outdoor aquaculture environment (fish pond).

This experiment found that the effect at this environment is at high level, where the PER value for side D is more than 1%. After sending packets at 50 ms, the effect can be minimised with the PER value of Side D become less than 1%. This research concludes that the multipath fading effect is exist in aquaculture environment. By using combination of PER, average RSSI, standard deviation, χ² test and Rice K analysis tools is able to analyse the multipath fading effect. This effect can be minimised by controlling time interval between packets transmission. From this research is obtained that WSN is feasible to operate in aquaculture environment.

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CHAPTER 1 INTRODUCTION

1.1. Background

A group of sensors that works together to sense environment parameters is very useful for monitoring system and scientific research. This system can help to improve certain techniques or mechanism of any fields. It can be an early warning system to avoid any system from crash. It can be an efficient intruder alarm of security system. It is useful for environmental protection and preservation.

Most conventional sensor systems use a lot of long cables and connectors. Cables and connectors are prone to failures resulting in the high cost of material, installation and maintenance. Because of these issues, a large number of sensors usage are not favourable. With the emergence of a new technology that is WSN (Wireless Sensor Networks), these costs and the related problems can be eliminated.

WSN can be defined from node and network perspectives. From the node perspective WSN is an embedded system that combines sensors, microcontroller and communication module that is powered by low voltage battery as shown by Figure 1.1(a). Sensors are the front end component that sense environment parameters such as temperature, humidity and pH. They can be a unit or multiple units and the same type or multiple types. Microcontroller coordinates node activities and process the sense data locally. By combining sensors and microcontrollers, sensors become smart and intelligent in terms of sensing capability and operations. Communication module

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transmits the processed data to the next node as well as receives data from others.

Usually the communication module use radio wave or microwave to communicate with each others. WSN protocol is less complex than the other wireless protocol such as WLAN/WiFi (IEEE 802.11 a/b/g) and Bluetooth (IEEE 802.15.3). Therefore, the protocol can be written and modified easily. Figure 1.1 (b) shows protocol architecture of WSN. Connectivity layer is applied in hardware and precisely manufactured, therefore developer can ignore the design of this layer. The lowest layer of WSN protocol that is implemented in hardware is called LR-WPAN (Low Rate Wireless Personal Area Network) with the standard of IEEE 802.15.4 (Chen, 2010). On top of LR-WPAN protocol, the commercial protocols like ZigBee, 6LowPAN, MiWi, WirelessHART etc were implemented that are available in market. This layer need to be configured only but not to be designed anymore. Developer has to develop program for application layer only. Sensor data can be displayed by alphanumeric characters that lead to low data rates communication design. This feature makes communication module consume less power for transmission and reception activities. The special thing about nodes is each unit is powered by a battery but can operate for a few months. This condition can be achieved by applying sleeping capability.

(a) Node functional block diagram (b) Node architecture Figure 1.1 WSN node design

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From network perspective, WSN consists of many nodes, a few routers and a base station that are connected wirelessly as shown in Figure 1.2. Nodes are distributed devices that sense the environment parameters. Routers are mediator that are for responsible to forwarding the nodes data. The base station collects all the data from nodes and routers, process them and relay them to other devices. The devices that can be connected to base station are telecommunication devices such as GSM (Global System for Mobile Communication) or internet, interface displays such as computer GUI (Graphical User Interface) or display panel or recording devices (database server or data logger). WSN can cover a large area and may consists of many nodes because it apply multihops communication. The network applies self-organise function that helps network topology to form automatically and change easily. The last reason to choose WSN is the use of free-licensed band to communicate with each other.

Figure 1.2 WSN topology

Aquaculture depends on water quality to produce fish. Good water quality helps to increase volume of fish production and return high revenue. While poor water quality affects fish mortality that decreases production and profitability. WSN can be used to monitor water quality. Fish farmer can gain benefit from this WSN application even though their challenges are to monitor large area, many ponds and variety of fish; they

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will still be able to manage water quality. Whereas, scientist can use WSN as a tool to improve water quality, to enhance production techniques and managements as well as developing new related applications.

Although to develop WSN application is not too difficult but to get WSN that operates in optimum conditions is challenging (Akyildiz, 2010). As mentioned before, WSN device is an embedded system. Any embedded system has performance constraints that are described by design metrics (Vahid et. al, 2002). An improvement made to certain metric will reduce the performance of others. There are several performance metrics for WSN system, such as energy consumption, data processing capacity, data processing and others of concern. One of the most important performance metric is the process of data transmission and reception.

For data reception process of WSN system, the receiver will generate ACK (acknowledge) signal to the transmitter after a received signal has been accepted. After a period of time, if the transmitter is not receive any ACK signal, the transmitter will retransmit the signal. The retransmission process will be repeated in a few trials until the transmitter receive the ACK signal. However, the retransmission process consume more energy and will shorten the node lifetime for a node that is powered by battery.

Retransmission process may also floods the network and it can degrade the efficiency of data delivery. The degraded of delivery process can lead to data loss problem. As a result, the system also may be degraded and cannot gather all information in the network. One of the contributors to the retransmission process is the faded signal propagation that is caused by the multipath fading effect.

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1.2. Multipath Fading Effect

Multipath fading is one of the signal propagation problem that is influenced by the environment condition (Phaebua et. al, 2008). Dobkin provides example of how fading modifies the original signal. Figure 1.3(a) shows the transmitter sending a signal of a few bits. This signal creates 3 rays, t1, t2 and t3. Ray t1 is transmitted directly from the transmitter to the receiver. At the same time, rays t2 and t3 are propagated in different directions. Both rays are being reflected and also arrived at the receiver. Figure 1.3(b) shows the original transmitted signal and the receiver is expected to receive this signal.

However, the receiver accepted 3 rays of the same signal at overlapping time as shown in Figure 1.3(c). As a result, the received signal of ray t1 has been modified by rays t2

and t₃. Figure 1.3(d) illustrates that this modified received signal cannot be interpreted by the receiver and then will be rejected.

(a) Multipath scenario

(b) Transmitted signal. (c) Multipath components. (d) Received signal.

Figure 1.3: Multipath fading effect (Dobkin, 2005)

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1.3. Problem Statement

There are several studies for WSN application system for aquaculture that has been done as described in Chapter 2. The studies that had been conducted are node development, system development and signal propagation. Among the research, the study on signal propagation is the least. It should be noted that a signal propagation study must be carried out before any other studies because a WSN system is not suitable for any application that its PER (Packet Error Rate) value is more than 1%. The signal propagation study for aquaculture applications is only carried out by (Harun, 2013).

The problem with this study is that it does not specify the PER. Therefore, the feasibility for WSN systems to operate in aquaculture environments is still unknown.

One of the cause that increase the value of PER to more than 1% is the propagated signal has been faded due to the effect of multipath fading. Multipath fading effect degrades the WSN system. Preferably, this effect is completely removed but it is impossible. Therefore, the best way is to reduce this effect to a minimum level but for WSN system, the reduction method is still unknown.

Multipath fading effect is depends on environment condition and to solve the problem, a signal propagation study must be conducted in the environment where the system will be implemented. In this research, signal propagation studies were conducted in aquaculture environments to obtained the information of signal propagation characteristics in these environment and their multipath fading effect.

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The study of signal propagation characteristics and multipath fading effect need certain method of analysing data. There a lot of methods to analyse signal propagation as described in chapter 2. The capabilities, performance and limits of these methods are for WSN system signal propagation studies are still unknown. The ignorance of this information leads to the problem of confused data interpretation and wrong conclusions.

If the problem of information ignorance of analytical methods can leads to the problem of confused data interpretation and wrong conclusions, the improper experimental setup can leads to the problem of distorted collected data. One of the improper experimental setup is the misplacement of WSN device position that does not follows their antenna radiation pattern and Fresnel zone rules. Therefore, the physical position of WSN devices must be studied too.

1.4. Objectives

The first objective of this research is to study the signal propagation characteristics of WSN devices and the devices physical position that influence signal propagation characteristics.

There are a number of WSN signal propagation studies using several analysis tools. These analysis tools have their own limitations and their effectiveness is still questionable. The second objective is to study the capability and performance of signal propagation analysis tools to analyse signal propagation data.

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The third objective of this research is to study WSN signal propagation characteristics in aquaculture environment. The chosen environments are an indoor fish hatchery and an outdoor fish pond. This research concentrates on multipath fading effect in both environments.

A lot of research and texts discuss about multipath fading effect but very few provide solutions to this problem. The fourth objective is to test controlling time interval between packets transmission method to reduce the multipath fading effect.

The fifth objective is to study the feasibility of WSN to operate in aquaculture environment. WSN is feasible to operate when multipath fading can be minimised and PER value is less than 1%.

1.5. Scopes

This research is limited to one of the wireless protocols that is called LR-WPAN IEEE 802.15.4 2003. This protocol is chosen because the data rate is suitable for sensor data. That is why world wide trend is using LR-WPAN for WSN. Although there are research that used Wi-Fi and Bluetooth as WSN, these standard data rates are excessive for sensor operation.

This research has studied the signal propagation of point to point communication or between 2 nodes only. The failure of this communication can represent the entire network failure. Therefore, only this basic communication type was analysed.

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