On the design of low power consumption water level monitoring station for urban environment based on wireless sensor network

Based on the context of ubiquitous wireless sensor network (WSN), design of a wireless sensor network and a low power water level monitoring station for urban environment are proposed in this paper. A ubiquitous WSNs based on a high performance and low power consumption Texas Instrument CC1110 module is presented and investigated.

ON THE DESIGN OF LOW POWER CONSUMPTION WATER

LEVEL MONITORING STATION FOR URBAN ENVIRONMENT

BASED ON WIRELESS SENSOR NETWORK

Nguyen Tuan Duc1*, Le Quoc Cuong2

Abstract: Based on the context of ubiquitous wireless sensor network (WSN),

design of a wireless sensor network and a low power water level monitoring station

for urban environment are proposed in this paper A ubiquitous WSNs based on a

high performance and low power consumption Texas Instrument CC1110 module is

presented and investigated Through this ubiquitous WSNs, water level measured

from many monitoring stations are sent to the base station via a GPRS/3G gateway

and then are forwarded to a data center In order to ensure a longterm operation

with a limited solar power supply in environment, a low power consumption design

of a water level monitoring station is also proposed The power consumption of the

proposed station is estimated and solar power supply calculation for this station is

also investigated With an advantage of low power consumption station and

ubiquitous wireless monitoring network, the system can be applied widely in urban

environment in developing countries like Vietnam

Keywords: Wireless sensor network, Low power consumption network, Energy efficiency, Water level

monitoring

1 INTRODUCTION

Following the research of United Nations Development Programe (UNDP), Vietnam is

a one 5 countries which are heavy influenced by climate change and the rise of sea level

For the record, every 1m of sea level rising will impact on 5% land resource, 11%

population and 7% agriculture and 10% GDP decreasing [1] There are more and more

evidences prove that climate change is increasing the intensity and density of environment

catastrophe in Vietnam Climate change also impact on water resource such as water

current, flood, and increasing evaporation, it will lead to the influence on social life and

food production activities Moreover, the salt intrusion and erosion because of sea level

rise which are threats to the economy and social life of the population

In many big cities, owing to climate change, the tide situation of river systems as well

as flooded situation by heavy rain are more and more serious The reason is that drainage

system is overloaded and jammed, it will lead to the economic and society damage

Especially, the flooded situation affects directly on citizen and companies activities In

order to react with climate change effects and limit the harmful effects of flooded situation

in big cities, the demand is to build a system which can monitor the water level on around

a city in order to track the river-canal level, tide and flooded situation, then based on that

data, suitable reactions will be made [2][3]

In recent years, wireless sensor network (WSN) technology has been deployed into

environment system as a new way to monitor and improve the relationship between human

and environment WSN system can help increase agricultural products and interact with

nature There are many researches for WSN in environmental monitoring applications in

couple years, by using sensor to observe the gradual change of environment in real-time

[4] Climatic sensor is spread on a specific area in order to measure the climatic data and

network system can send these data to people for processing [5][6]

A combining network is considered as an ubiquitous wireless sensor network that can

allow wireless sensor devices to connect to control center at anytime and from anywhere

proposes an optimum solution for a water level monitoring station In current market, a high cost up to 60000 USD for a monitoring station and a collecting data system will limit the deployment in a huge number of stations in developing countries A low cost for water level monitoring station by using low cost devices and without maintaining cost would bring an opportunity to apply this system in large-scale areas for developing countries like Vietnam [8] [9]

This paper is organized as follows Section 2 shows the design of overall water level monitoring system based on a ubiquitous WSN In Section 3, wireless sensor network hardware is selected and water level monitoring station hardware design is proposed In Section 4, the power consumption estimation of the monitoring station is investigated to prove the energy efficiency In order to show the possibility of this design, experiments and results are presented in Section 5 Finally, a conclusion is given in Section 6

2 OVERALL SYSTEM DESIGN

In order to deploy a monitoring network which can cover all a city, this paper proposes

a network system based on the operation procedures:

a) A monitoring network cover whole the city and track the water level of river-canal and the flooded level on the street when tide or heavy rain happens in many area in the city

b) A monitoring parameter of water level and flooded situations will be sent automatically to data center in real time Based on 3G/GPRS and wireless sensor network This combine network is called ubiquitous wireless sensor network and it has many advantages when compared with only cellular network or wired network

c) Data of water level will be stored at data center and people can access easily based on Web interface and Internet connection

The overall structure of water level monitoring system is shown in Fig 1 This network

is divided into many cluster by combining GPRS/3G and WSN Each cluster has one Data Station and many water level stations After getting data of water level, the station will send these data to Data Station by a wireless node The role of Data Station is that received message from water level station and then processing, storing and transmitting these data

to Database Center

The advantages of this design is low cost because there is no need to integrate GPRS/3G modem for all stations which have a high cost for cellular network Moreover, this system do not depend on mobile service

Figure 1 Overall design for water level monitoring system

3 HARDWARE DESIGN

A Energy efficiency wireless sensor network

Goals of this task is investigating a wireless hardware with low cost, low power

consumption and reliable transmission in urban environment, this section focuses on study

of a suitable wireless hardware for the Water level monitoring network A comparison of

some modern transceivers on market is shown on Table I, then a suitable transceiver will

be chosen based on these criteria above

Following Table I, CC1110 device has the advantage of integrated MCU, it will lead to

saving cost for a wireless module:

a) CC1110 has a higher reliable transmission than MRF24J40MD At 1.2 kbps data

rate, CC1110 has a receive sensitivity -110 dBm with Packet error rate is 10−2

while ZigBee device MRF24J40MD has Bit error rate is 10−3 at the same receive

sensitivity Beside, MRF24J40MD integrates with a power amplifier, so that energy

consumption will be much higher than CC1110 at transmission mode

b) In the case of transmission distance, CC1110 has longer transmission than the other

(the range up to 1.2 Km in free space and line of sight), it can also transmit signal

frequency band is not suitable

Table I Hardware comparison of WSN nodes

Beside some practical testing range for CC1110, it is easy to see that CC1110 wireless device is an appropriate wireless module for a water level monitoring station [10] Fig 2 illustrates for CC1110 mini development kit

Figure 2 CC1110 mini development kit

B Water level monitoring station

Fig 3 shows the structure of hardware design water level station There are four

blocks: Sensors, Data logger, Gateway and Power supply Since the node platforms is

design with solar cell, a large capacity battery and reliable DC-DC converting circuit have

been well considered for the power supply module

Figure 3 Block diagram of Data station

a) Water level sensor: This paper proposes a method which uses pressure sensor for

water level measurement The principle of this method is use one sensor to measure the

pressure of water Level of the liquid will be determined based on the pressure at the

sensor position

For automatic monitoring station design, water level sensor should be high quality for a

long term operation in environment The pressure sensor like Heron pressure sensor is a

suitable solution for this design which is illustrated in Fig 4 This sensor is adaptable for

this water level monitoring application, with a good noise avoidance function and can

sustainable operate in lengths down to 600m under the water This sensor need 12V power

supply and give an industry standard output 4-20 mA signal

Figure 4 Pressure sensor for water level measurement

In data processing part of monitoring station, an Analog to Digital Converter (ADC) is used to convert the electricity current 4-20 mA from sensor This signal is converted to voltage signal and then processed by the MCU This task is done by the Data logger and create the output from 0 to 5V for water level calibration

b) Data logger: Data logger is an electronic programmable instrument based on a

power-full micro-controller AT-mega2560 that records environmental data from sensors

In this design, our data logger can hold up data for several months by using a high capacity

SD card module and is equipped with a 10-bit-resolution ADC and a wide variety of analog and digital input/output (I/O) ports to interface with numerous environment sensors such as water level and many different types of sensor

To enable communication with other external devices, Data logger is equipped a range

of peripheral ports such as RS-232, USB and Ethernet on the gateway module

c) Gateway: Connecting to Data logger, the gateway block provide a standard set of

on-board peripherals to interface with external communication modules With four UART ports on chip, AT-mega2560 is well suited to communicate with various communication modules

For example, two UART work as RS-232 serial port to interface with GPRS modem and CC1110 wireless module, a FT232 port to interface with computer, and another COM port to interface with the Ethernet module Wireless sensor network CC1110 module operating in 868 MHz are always integrated in the gateway of monitoring station (shown

as sub Ghz wireless on the Fig 3)

d) Power Supply: Power management is essential for long-term operation To survive

extreme weather conditions in long-term operation, we propose a solar supply power system with a battery that help the monitoring station work at least 7 days without recharging Power supply design is investigated in next section

4 POWER CONSUMPTION ESTIMATION AND POWER SUPPLY DESIGN

In this section the power consumption estimation of the designed monitoring is calculated Then, the capacity of a back-up battery and solar panel power are also proposed based on the power consumption of station and the 7 working days requirement

In order to reduce the power consumption, the water level sensor, the data logger, MCUs, GPRS modem and CC1110 are kept Active or Idle depending on each working states

The radio transceiver is a big energy consumer: keeping it on all the time may lead to a negative energy balance Consequently, duty cycling provides an effective way to achieve energy efficiency which is calculated by the ratio of Active time and Total time In this

setup, the wireless modem wakes up for 30 seconds every 15 minutes for data collection

which is equivalent to a duty cycle of about 3.3%

To calculate the duty circle of sensor and CC1110 transceiver Let assumes the sensor

get data from environment every 5 minutes and take 10 seconds for each time Beside,

CC1110 transceiver transmits data every 15 minutes per time in two ways communication,

transmit time is set 1 minutes Duty circle of sensor take 3.3% and transceiver take 6.7%

In this design, the duty cycle of active and Idle states of each component is presented

on Table II

Table II Data Station Power Consumption Estimation

Table II illustrates also the power consumption (including average current and working

voltage) of each component inside the monitoring station The total average power draw of

this monitoring can be calculated as 207mW which is very efficient

Using the power calculation in Table II, if a battery capacity of 4000mAh (12V

voltage) is used, the theoretical time for the next charging is given by

4000(mAh)*12(V)/207(mW) = 231 hours (or 9.7 days) In practice, a lead-acid battery

cannot be 100% discharged repeatedly Therefore, it is necessary to derate the battery by

some amount, generally 25% In this case, 25% of 4000mAh is about 3000mAh So the

practical time between 2 recharging times is now given by 3000(mAh)*12(V)/207(mW) =

173 hours (or 7.2 days)

Hence, the battery may support the system for more than 7 days without recharging,

that satisfy the design goal Cause efficient working hours per one day of a solar panel is 6

hours average, the capacity of a solar panel should be at least 4 times the average power

consumption of the load in general By the above calculation in the Table II, the average

power consumption is 207(mW), then a minimum power load of solar panel would be

about 207mw*4= 828mW This is a reason why a 12V and 1W solar panel is selected for

power supply design

4 EXPERIMENT AND HARDWARE RESULT

A CC1110 distance test

Table III shows a practical range testing of CC1110 module in real case of a city

environments Results of transmission distance test in Table II prove that CC1110

transmission range is very appropriate for the proposed water level monitoring station

network where node-to-coordinator distance is typically less than 500m when sending

CC1110 allows a small size wireless module to be integrated in data-logger circuit of water level monitoring station Moreover, Texas Instrument network protocols (SimpliciTi ore wireless M-Bus) supports for CC1110 transceiver, so that we can deploy an efficient star routing network for one Cluster in Fig 1

The structure of SimpliciTI protocol is presented in Fig 5 To extend the network coverage, this protocol also supports range extenders function

Figure 5 SimpliciTI protocol structure

B An experiment monitoring station

Fig 6 shows some components of a real experiment monitoring station including: Data logger (and LCD screen), sensor ADC board, GPRS module and battery of power supply module This station has been tested for a long time in our Lab at International University

of HCMC

Figure 6 Experimental design of water level monitoring station

5 CONCLUSION

In this paper, the energy efficient system for water level monitoring in urban

environment is proposed This system bases on ubiquitous WSNs and low power

consumption water level monitoring station

The power efficiency of wireless sensor network based on Texas instrument CC1110

hardware have been investigated and the power consumption of the monitoring station

have been estimated to prove the energy efficiency of this system The low power

consumption of the proposed monitoring station ensures that it can work for 7 days with a

3000mAh 12V battery In the end, data of wireless transmission distance test of CC1110

wireless module and hardware implementation of the monitoring station have been shown

ACKNOWLEDGEMENT: This research was supported by the Vietnam National

Foundation for Science and Technology Development (No 102.01-2011.22)

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TÓM TẮT

THIẾT KẾ TRẠM GIÁM SÁT MỰC NƯỚC TIÊU THỤ ĐIỆN NĂNG THẤP CHO MÔI TRƯỜNG ĐÔ THỊ DỰA TRÊN CÔNG NGHỆ MẠNG CẢM BIẾN KHÔNG DÂY

Dựa trên công nghệ mạng cảm biến không dây thông suốt, thiết kế mạng cảm

biến không dây thông suốt (WSN) và trạm giám sát mực nước điện năng thấp cho

môi trường đô thị được đề xuất trong bài báo này Mạng WSN dựa trên mô-đun

không dây hiệu năng cao và công suất thấp Texas Instrument CC1110 được nghiên

cứu Thông qua mạng WSN này, mực nước được đo đạc từ các trạm giám sát sẽ

được truyền về trạm gốc và chuyển tiếp về trung tâm dữ liệu thông qua thiết bị cửa

ngõ GPRS/3G Để đảm bảo sự hoạt động liên tục với nguồn cấp năng lượng mặt

trời có hạn, thiết kế tiết kiệm năng lượng của trạm giám sát cũng được đề xuất Mức

tiêu thụ năng lượng của trạm sẽ được ước lượng và tính toán về nguồn cấp năng

lượng mặt trời sẽ được thực hiện Với ưu thế về tiêu thụ năng lượng thấp và mạng

cảm biến không dây thông suốt, hệ thống trên có thể ứng dụng rộng rãi trong môi

trường đô thị ở các quốc gia đang phát triển như Việt Nam

Từ khóa: Mạng cảm biến không dây, Giám sát môi trường, Trạm giám sát mực nước, Mạng tiêu thụ năng

lượng thấp

Received date, 13 th June, 2016

Revised manuscript, 15 th March 2017

Published on 26 th April 2017

Author affiliations:

1

International University, Vietnam National University

2

Department of Information and Communications of HCM city, Vietnam

*Corresponding author: ntduc@hcmiu.edu.vn