Green radio for energy saving in mobile towers

CHAPTER 1 INTRODUCTION1. INTRODUCTIONThere is a rapid growth in the number of mobile users and hence we use higher-data-rate mobile broadband. Since 2006, data traffic on wireless networks has grown by approximately 400% and is expected to continue to increase rapidly in the coming years. The widespread use of complex, spectrum efficient techniques to support such high data volumes, the demand for higher data rates and the ever-increasing number of wireless users translate to rapidly rising power consumption. Currently consuming 3% of the energy and causing 2% of the CO2 emissions globally, the Information & Communication Technology (ICT) industries are facing an increase in associated energy consumption of 16-20% per year. Furthermore, the energy costs for mobile operators can be as high as half of their annual operating budgets.

Fig1.1 Power consumption in MCS

Fig1.2 Time VS CostAnd the present wireless mobile networks are not Energy-Efficient. For continuous and instantaneous operation, conventional types of energy resources are preferred. But, Nuclear energy is not used as the source of fuel because of the hazardous impact caused by the radio-active waste, which cannot be disposed permanently. Thus, diesel generator is preferred over other types of generators. A typical diesel generator, used for supplying power for communication purpose, consumes ONE MILLION GALLON (1MG) of diesel per day. This results in emission of huge amount of carbon-dioxide (CO2). Tons and tons of liters of diesel are consumed by mobile towers. India has around 3.1 lakh towers, of which 70 percent are located in rural areas where grid connected electricity is not available. As a result, 60 percent of the towers are powered by diesel generators which produce a total of 5.3 million liters of carbon dioxide every year. Many so-called standby generator sets installed at urban cell towers are in fact running for several hours every day. With the sustained rise of global energy prices, the fuel costs of running these diesel, natural gas or propane generators are a major piece of the Total Cost of Ownership (TCO) for these cell towers. For example, the fuel cost (as a 9percentage of TCO) could be as high as 64% for a typical 12 kW diesel generator running for about eight hours per day. This cost is driving many telecom cell tower operators to consider other power system options.Power consumption per base station GSM WCDMA

Now 800 watts 500 watts

Target 650 watts 300 watts

Table 1.1 power consumption/BTSElectricity consumption attributed to information and communication technology is also increasing rapidly. This is because of the rising usage and new product and service launches. The source for towers is based on the power requirement. A critical mobile network consumes 40-50MW approximately, even excluding the power consumed by users handsets. And in developing countries direct electricity connections are not readily available, so an operator must go for generator as the source of power.

Fig1.3 Cellular network power consumptionThe power consumption of various elements has been shown in above figure. It clearly states that reducing the power usage of the base station will reduce the power consumption as it consumes the maximum power. Fig 1.4 Co2 emissions per subscriber per year for base stations and mobile handsets It is seen that the operational energy for mobile handsets is much less than that of base station. It also shows that the manufacturing or embodied energy is greater in mobile handsets when compared to base station. This is just for one single tower. So imagine the impact due to several million towers installed in a country. Thus, there is a need on environmental grounds to reduce the energy requirements of radio access networks. Our objective is to reduce the energy consumption in base stations and reduce the amount of CO2 emission. We have to keep controlling system in every base station for switching purpose. To have complete control over base station we prefer to use PC. This enables us to implement SCADA concept to monitor all the base stations and provides full control over them. Reducing carbon emissions and OPEX for wireless cellular networks are two key reasons behind the development of the Mobile Green Radio program. This technology helps in minimizing the power consumption, reduces CO2 emission and prevents depletion of fossil fuel. The Green Radio project is pursuing energy reduction from two different perspectives. The first is to examine alternatives to the existing cellular network structures to reduce energy consumption. The second approach is to study novel techniques that can be used in base stations or handsets to reduce energy consumption in the network.Due to the tremendous upswing of mobile Internet access demand, the cellular wireless system is currently transitioning to LTE. This next-generation mobile infrastructure provides broadband access and enables new classes of applications for mobile users. With the emerging traffic demand, mobile operators are under pressure to enhance their infrastructure in a competitive time frame. However, the investment to enhance the infrastructure does not always pay off because the average revenue per connection continues to decrease. To overcome such a price-pressure trend, energy saving is one of the key subjects for mobile operators total cost of ownership reduction. Because the base station accounts for most of the energy consumption .Solar energy and wind energy are the real and unpolluted energy forever. Demand of electrical energy and less availability of present resources. we need to develop a system which will be efficient to produce more electrical energy by accepting natural resources like sunlight, wind, hydro etc.we would like to improve the present solar system to produce more electrical power. Using of existing sensors, embedded technology and mechanical designs, we can improve the energy saving system. According to our system, one time investment will lead good payback before investigating the solar power, we would like to look the energy scenario of india till 2010.

CHAPTER 2LITERATURE SURVEY According to T.ELDER, scientist from Ericson in long-term-evolution-advanced (LTE-advanced), heterogeneous deployments of relays, femtocells and conventional macro cells are expected to provide coverage extension and throughput enhancement, while significantly lowering the energy consumption and total-cost-of-ownership (TCO) in cellular networks. This study presents a methodology for estimating the total energy consumption, taking into account the total operational power and embodied energy, and TCO of wireless cellular networks, and in particular provides a means to compare homogeneous and heterogeneous network (HetNets) deployments. The authors introduce realistic energy models and energy metrics based on information available from mobile-network operators (MNOs) and base stations manufacturers. Additionally, up-to-date operational and capital expenditure (OPEX and CAPEX) models are used to calculate TCO of candidate networks. The authors evaluate two scenarios for Het Nets, namely a joint macro-relay network and a joint macro-femtocell network, with different relay and femtocell deployments densities. The results obtained show that compared to macro-centric networks, joint macro-relay networks are both energy and cost efficient, whereas joint macro-femtocell networks reduce the networks TCO at the expense of increased energy-consumption. Finally, it is observed that energy and cost gains are highly sensitive to the OPEX model adopted.According to Yan-Chen et al in Fundamental Trade-offs on Green Wireless Networks Presents an insightful design framework for energy-efficiency-oriented mobile wireless networks, which consists of four fundamental trades-offs: deployment efficiency vs. energy efficiency, spectrum efficiency vs. energy efficiency, bandwidth vs. power, and delay vs. power. Within this article, the authors thoroughly analyze how to balance the deployment cost, throughput, and energy consumption in the network as a whole, how to guarantee the achievable rate while maintaining energy consumption of the system on a given available bandwidth, how to utilize the bandwidth and the power needed for transmission at a given target rate, and how to counterpoise the average end-to-end service delay and average power consumed in transmission, respectively.According to Hanna Bogucka and Andrea Contiit verifies that adaptive communication techniques have degrees of freedom to potentially be exploited for energy saving; meanwhile, the target performance metrics can be satisfied as well, which depend on various system parameters such as the diversity technique, the energy partition between data and pilot symbols for channel estimation, and the constellation signaling. As a case study, the authors also investigate single-carrier as well as multicarrier communication systems applying both margin-adaptive and rate-adaptive pilot-assisted transmission to quantify the relevant energy savings opportunities.According to Congzheng Hanetal it provides an in-depth overview of the ongoing Mobile VCE Green Radio project, which aims to establish novel approaches to reducing the energy consumption of wireless links, especially improving the design and operation of wireless base stations. Through the project, it has been shown that base stations can have much higher operational energy budgets than mobile terminals; therefore, appropriate modeling of the energy consumption of base stations is an important issue for decreasing the energy consumption of whole mobile communications systems.According to Eunsung Oh et alitdepicts how dynamic operation of cellular base stations, in which redundant low-traffic base stations are switched off, can generate significant energy savings advantages. Based on real cellular traffic traces and information regarding base station locations, the authors discuss the first-order approximation of the percentage of power saving that can be expected by turning off base stations during low traffic periods while maintaining coverage and inter operator coordination. As we can see, the four articles selected above are mainly focused on typical scenarios of mobile wireless communications and access networks.According to Jayant Baliga et al it provides detailed analyses on the corresponding energy consumptions of digital subscriber line, hybrid fiber coax networks, PONs, fiber to the node, point-to-point optical systems, UMTS (WCDMA), and WiMAX. The authors conclude that PONs and point-to-point optical networks are the most energy-efficient access solutions at high access rates.According to Suresh Singh and Candy Yiuit illustrates a novel solution for linear scaling of energy usage with the traffic loads within the Internet, which involves aggregating traffic from multiple input links prior to feeding them to the switch interfaces, so as to maximize the number of interfaces put to sleep. The authors arrive at a promising result: energy consumption, measured as fraction of awaking interfaces, scales linearly with load for all loads and the proposed algorithms are actually deterministic without any packet loss.According to Chunming Wu et al it discusses how to construct energy-efficient reconfigurable router with power aware routing mechanism through virtual networks with advanced rate adaptation processing inside the Internet router. In particular, by taking into account of the Internet behavior features and the modular architecture of routers, the GRec Router designed in this article takes advantage of various opportunities and means to greatly cut down the power dissipation at the network, node, and function level.2.1 EXISTING SYSTEMIn the existing system all mobile towers are kept on in a particular locality rrespective of the number of users. All the mobile towers are in ON state even if the users are very less Fig 2.1 Existing systemAs a result high power consumption occurs. A typical mobile phone network may consume approximately 40-50MW, even excluding the power consumed by users handsets. When direct electricity connections are not readily available, these service providers use diesel to power their network. As a result, a polluted environment is established and a whole of about 1% of the total power generation is being consumed by the mobile networks itself. In addition to this the lighting and cooling units are always in on state even in the day thereby considerably increasing the power consumption rate day by day.Since 2006, data traffic on wireless networks has grown by approximately 400% and is expected to continue to increase rapidly in the coming years. The widespread use of complex, spectrum efficient techniques to support such high data volumes, the demand for higher data rates and the ever-increasing number of wireless users translate to rapidly rising power consumption. Currently consuming 3% of the energy and causing 2% of the CO2 emissions globally, the Information & Communication Technology (ICT) industries are facing an increase in associated energy consumption of 16-20% per year. Furthermore, the energy costs for mobile operators can be as high as half of their annual operating budgets. And the present wireless mobile networks are not Energy-Efficient. Tons and tons of liters of diesel are consumed by mobile towers. India has around 3.1lakh towers, of which 70 percent are located in rural areas where grid connected electricity is not available. As a result, 60 percent of the towers are powered by diesel generators which produce a total of 5.3 million liters of carbon dioxide every year. Many so-called standby generator sets installed at urban cell towers are in fact running for several hours every day. With the sustained rise of global energy prices, the fuel costs of running these diesel, natural gas or propane generators are a major piece of the Total Cost of Ownership (TCO) for these cell towers. For example, the fuel cost (as a percentage of TCO) could be as high as 64%for a typical 12 kW diesel generator running for about eight hours per day. This cost is driving many telecom cell tower operators to consider other power system options.Drawbacks of the existing system: Base stations consumes 1 million liters of diesel per day . Base stations consumes around 2% of the total power production in india. This is used for 30% of towers (on-grid). On-grid towers are one which has direct connectivity from the power grid i.e., un-interruptable power supply. Remaining 70%(off-grid) of towers uses non-renewable energy sources like diesel and this is major cause for the emission of the green house gases. Information and communication technologies (ICTs) contribute around 2.5% of global house gas emission. Service providers in india consume around 2 billion liters of diesel which is around 3.5% of total consumption in india i.e., next to railways.2.2 IMPACTS &CONSEQUENCES OF EXISTING SYSTEMBecause of the continuous operation, more fuel is consumed. This results in high power consumption rate, high CO2 emission rate, depletion of fossil fuels, higher operating expenditure (OPEX) costs, many other ecological imbalances ( like acid rain, green house effect, ozone layer depletion etc).Hence we are moving to novel technologies where we can reduce the power consumption in base stations by finding user frequency, temperature, humidity & light intensity.

CHAPTER 3 PROPOSED SYSTEM Green Radio focuses to reduce the energy consumption in base stations and reduce the amount of CO2 emission. We have to keep controlling system in every base station for switching purpose. To have complete control over base station we prefer to use PC. In this technology, the mobile-communication tower in an area is turned ON, based on the frequency of users present in that area. In general, within a pre-defined control area, there will be multiple towers operating (of same network type). And each tower has pre-defined user-strength capacity, up to which it can operate. Thus, based on the user strength in a region, the number of towers in that particular region is turned ON and remaining towers are kept in IDLE STATE. When the no of users of the current tower reaches a predetermined value the responder frequency is sent to the nearby efficient tower to take up the remaining load by means of wireless sensors networks.

Fig 3.1 Proposed systemWe also monitor certain parameters, which can help in reducing energy consumption .The parameters are cooling fan and light indicators .The light which is present on the top of the tower glows throughout the day which is not necessary &cooling fans runs continuously. In order to control these parameters automatically, we use micro-controller based embedded system. The PIC micro-controller is used to do the control job and send the signal to a computer. Here, PIC micro-controller is interfaced with all the above mentioned Integrated chips . Each of those ICs perform different task whose output is given to PC through PIC micro controller. We use LDR to monitor the light intensity around the tower to determine day-break and night. We use two thermistors to determine temperature and moisture content. There is standard value fixed for all these parameters. When it deviates from that, the switching action takes place through relay circuits. We use four relays to monitor each of temperature, humidity, light intensity and frequency. In our model, we use hybrid circuit to generate energy using solar and wind turbines.3.1 BLOCK DIAGRAM OF GREEN RADIOThis project mainly consists of pic16F877A, sensing circuits and relays. Lets have the detailed explanation of every component in the following section

Fig 3.2 Block diagram of green radioVoltage sensing, current sensing circuits are used to calculate number of users Thermistor and light dependent resistors are used to measure temperature ,humidity and intensity of light. Responder frequency is nothing but a signal sent to another antenna intimating that the transmitted master antenna has reached the maximum number of users and requesting the slave antenna to switch on .The 40 pin IC has five I/O ports, fifteen interrupts and eight A/D input channels. It is used to control and monitor different parameters like Temperature, Humidity, Light Intensity, Responder Frequency, UPS, Diesel Generator, Voltage and Current. All these are given to the 8 analog input channels and corresponding control action is taken if there is any violation of pre-defined constraint .The control action is done by using relays for switching antennas. In this project we connect the kit to personal computer for virtual screening of the BTS (base station), battery level, number of users, responder frequency, AC, slave tower, light and power amplifier mode. We interface the kit to personal computer using RS232.Circuit of green radio

J112R31kC2C3780513VINVOUTVCC+C1R210kU3MAX23213451615261291110138147C1+C1-C2+C2-VCCGNDV+V-R1OUTR2OUTT1INT2INR1INR2INT1OUTT2OUTVCC1N4148+C910mfd10mfdVCCSW1SW PUSHBUTTONJ3JUMPER12FLASH BOARD+C710mfd+C1210mfdC80.1mfdU2PIC16F877A89101214151617181920212223242526272829303111323456733343536373839401132RE0/RDRE1/WRRE2/CSGNDOSC2/CLKOUTRC0/T1OSO/T1CKIRC1/T1OSI/CCP2RC2/CCP1RC3/SCK/SCLRD0/PSP0RD1/PSP1RD2/PSP2RD3/PSP3RC4/SKI/SDARC5/SDORC6/TX/CKRC7/RX/DTRD4/PSP4RD5/PSP5RD6/PSP6RD7/PSP7GNDMCLROSC1/CLKINRA0RA1RA2RA3RA4/TOCKIRA5/SSRB0/INTRB1RB2RB3RB4RB5RB6RB7VDDVDD+C1110mfdJ212Y1CRYSTALC130.1mfdCONNECTOR DB9594837261-+D2BRIDGE1432D3LEDC60.1mfdSG28PRI2+C510mfdD1+C41000mfdVCCR11k+C1010mfd Fig 3.3 Circuit diagram of green radio

The above figure is the complete circuit diagram of green radio. It consists of signal conditioning board ,PIC microcontroller board, relay board, RF transmitter board, RF receiver board, hybrid board, power supply.Signal conditioning board is used to modify the power supply as we are getting 230 v Ac power but we need 5/12 v dc power for PIC and ICs for the operation. It also contains voltage sensing and current sensing circuits to calculate number of users. All the inputs like temperature, humidity, intensity of light is measured using thermistors, LDR and are given to the PIC16F877A.All the inputs given to the PIC microcontroller should in the range of 0-5v,this manipulation will be done by using signal conditioning board. The output of voltage sensing and current sensing i.e., the number of users is also given as input to the PIC microcontroller which results in predefined action taken by the microcontroller with the help of relays. Relay board consists of relay driver and relays. Relay driver is used to drive the relays. Relays is used for switching of antennas based upon the number of users which is calculated in the signal conditioning board using current sensing and voltage sensing circuits.RF communication board has two parts namely RF transmitter and RF Receiver. Here the communication takes place using 433.92MHZ which is unlicensed. RF transmitter is used to send a responder signal using wireless transmission. RF receiver receives the responder signal and sends to the antennas for controlled switching operation of antennas.Hybrid board is used to generate power using solar panels and wind turbines. It combines the both solar energy and wind energy to form hybrid power.The resulting operation will be observed using visual basic software in PC, thus we connect the kit to the PC using MAX232 which acts as connector.The detailed explanation about each board is as follows:3.2 SIGNAL CONDITIONING BOARDAll the electronic components starting from diode to Intel ICs only work with a DC supply ranging from +5vto+12v. We are utilizing for the same, the cheapest and commonly available energy source of 230v-50Hz and stepping down, rectifying, filtering and regulating the voltage to 5-12 volts. This can be pictorially shown as follows

TransformerRectifier Smoothing filterRegulator 230 V5V DCAC Fig 3.4 Block diagram for Signal Conditioning Board

3.2.1 Step down transformerWhen AC is applied to the primary winding of the power transformer it can either be stepped down or up depending on the value of DC needed. In our circuit the transformer of230v/15-0-15v is used to perform the step down operation where a 230V AC appears as 15V AC across the secondary winding. The current rating of the transformer used in our project is 2A. Apart from stepping down AC voltages, it gives isolation between the power source and power supply circuitries.3.2.2 Rectifier unitIn the power supply unit, rectification for large amounts of DC power is achieved usinga bridge rectifier. A bridge rectifier of four diodes (4*IN4007) are used to achieve full wave rectification. Two diodes will conduct during the negative cycle and the other two will conduct during the positive half cycle. The DC voltage appearing across the output terminals of the bridge rectifier will be somewhat less than 90% of the applied rms value

Fig 3.5 Bridge rectifier and its output waveformNormally one alteration of the input voltage will reverse the polarities. Opposite ends of the transformer will therefore always be 180 deg out of phase with each other. For a positive cycle, two diodes are connected to the positive voltage at the top winding and only one diode conducts. At the same time one of the other two diodes conducts for thenegative voltage that is applied from the bottom winding due to the forward bias for that diode. The output obtained is not a pure DC and therefore filtration has to be done.3.2.3 Filtering unitFilter circuits which are usually capacitors acting as a surge arrester always follow the rectifier unit. This capacitor is also called as a decoupling capacitor or a bypassing capacitor, is used not only to short the ripple with frequency of 120Hz to ground but also to leave the frequency of the DC to appear at the output. A load resistor is connected so that a reference to the ground is maintained. C17 is for bypassing ripples. C21 is used as a low pass filter, i.e. it passes only low frequency signals and bypasses high frequency signals. The load resistor should be 1% to 2.5% of the load.

Fig 3.6 Filtering/smoothing capacitor and its output1000F/25v: for the reduction of ripples from the pulsating.10F/25v : for maintaining the stability of the voltage at the load side.0.1F: for bypassing the high frequency disturbances.

Fig 3.7 Transformer with rectifier and smoothing3.2.4 Voltage regulatorsThe voltage regulators play an important role in any power supply unit. The primary purpose of a regulator is to aid the rectifier and filter circuit in providing a constant DC voltage to the device. Power supplies without regulators have an inherent problem of changing DC voltage values due to variations in the load or due to fluctuations in the AC liner voltage. With a regulator connected to the DC output, the voltage can be maintained within a close tolerant region of the desired output. IC7805, 7812 and7912 is used in this project for providing +5v, +12v and 12v DC supply respectively.

Fig 3.8 Dual power supply

Fig 3.9 Rectifier and regulator with regulated DC voltage3.3 DATA ACQUISITION UNIT All the necessary inputs required for the project are collected here using sensing circuits/sensors. In this project voltage sensing circuit, current sensing circuit, thermistor, light dependent resistor (LDR) are used. In this project voltage and current are to be sensed to measure the number of users of a particular antenna. Each user consumes 3watts of power form an antenna base station. So dividing total power consumed by the load/antenna with 3 gives the total number of users in a particular area. Thermistor is used to sense the humidity and temperature of the atmosphere. Light dependent resistor is used to measure the intensity of the light. Pictorially voltage sensing and current sensing can be shown as below

Voltage sensing circuitCurrent sensing circuitLOAD/ ANTENNAPOWER SUPPLY

Fig 3.10 Block diagram for calculation of number of users3.3.1 Voltage sensing circuit:

Fig 3.11 voltage sensing circuitBridge rectifier can be used to convert AC to DC. But a single conducting diode drops the voltage of 0.6v.During each cycle, 2 diodes are in conduction mode. So, totally 1.2v is dropped across it. This is undesirable because the voltage (i.e.) to be measured is about 5v. Hence, as mentioned above full wave rectifier designed using op-amp is used, due to the drawbacks faced in using bridge rectifier. OP-AMPS are devices, which have high input impedance and low output impedance. Hence they are used for rectification purpose, as they do not any device.In the rectifier circuit, A1 (first op-amp) is an inverting unity gain amplifier. The output from A1 is added to the original input signal in A2 (second op-amp)(inverting summing mixed gain amplifier). In this circuit, the diode is always in conduction mode and D1 is kept at virtual ground .Ein feds A2 through a 20K resistor and A1 through a 10 resistor.In this circuit diagram, there is a potential divider to divide the potential so that a sample of only 0.454v is given as an input to a rectifier. The gain of Op-amp (A1) is 1.the op-amp (A2) has two parts having the gain of 1and 2 respectively.During positive half cycle the op-amp A1 produces an output of 0.454v. Op-amp A2 produces an output of 0.908v across the path having gain of 2 and an output of 0.454v across the path having a gain of 1.thus, the resultant output voltage is 0.454v.it can be amplified to the required voltage by varying the trim pot.During negative half cycle the op-amp A1 produces an output of 0.454v.hence the diode does not conduct .The input of path2 of A2 is 0v,hence the output voltage is 0v.But the input of path1 of A2 is 0.454v.and hence the across path1 is 0.454v.it can be amplified to require voltage by varying the 500k trim pot. The 500K trim pot is adjusted so that a full-scale output voltage of 5v is produced for a primary voltage of 230v.A capacitor is connected to A2 so that it acts as an integrator. Hence the output voltage is a pure DC voltage it is then given to ADC. The 1K resistor is used to limit the current of 5mA.

3.3.2 Current sensing circuit

Fig 3.12 current sensing circuitBridge rectifier can be used to convert AC to DC. But a single conducting diode drops the voltage of 0.6v.During each cycle, 2 diodes are in conduction mode. So, totally 1.2v is dropped across it. This is undesirable because the voltage (i.e.) to be measured is about 5v.Hence, as mentioned above full wave rectifier designed using op-amp is used, due to the drawbacks faced in using bridge rectifier. OP-AMPS are devices, which have high input impedance and low output impedance. Hence they are used for rectification purpose, as they do not any device.In the rectifier circuit, A1 is an inverting unity gain amplifier. The output from A1 is added to the original input signal in A2 (inverting summing mixed gain amplifier). In this circuit, the diode is always in conduction mode and D1 is kept at virtual ground .Ein feds A2 through a 20K resistor and A1 through a 10 resistor.In this circuit diagram, there is a potential divider to divide the potential so that a sample of only 0.454v is given as an input to a rectifier. The gain of Op-amp (A1) is 1.the op-amp (A2) has two parts having the gain of 1and 2 respectively.During positive half cycle the op-amp A1 produces an output of 0.454v.Op-amp A2 produces an output of 0.908v across the path having gain of 2 and an output of 0.454v across the path having a gain of 1.thus, the resultant output voltage is 0.454v.It can be amplified to the required voltage by varying the trim pot.During negative half cycle the op-amp A1 produces an output of 0.454v.hence the diode does not conduct .The input of path2 of A2 is 0v,hence the output voltage is 0v.But the input of path1 of A2 is 0.454v.and hence the across path1 is 0.454v.it can be amplified to require voltage by varying the 500k trim pot. The 500K trim pot is adjusted so that a full-scale output voltage of 5v is produced for a primary voltage of 230v.A capacitor is connected to A2 so that it acts as an integrator. Hence the output voltage is a pure DC voltage it is then given to ADC. The 1K resistor is used to limit the current of 5mA.3.3.3 Thermistors The parameters which are to be controlled in base stations are the power supplied to cooling unit and lighting process. We can see that it reduces the power consumption by at least 30% (considering one single BTS). So, on the whole, it contributes to a major portion of power consumed all over the world. Thus, it reduces that major portion of power instead of being wasted. Using thermistor we measure the temperature and humidity of the air. If the temperature is lesser or the humidity is higher than the predefined limits, then we switch off the air conditioners and make use of Blowers. Fig 3.13 Air blowerAir blowers generally use centrifugal force to propel air forward. Inside a centrifugal air blower is a wheel with small blades on the circumference and a casing to direct the flow of air into the center of the wheel and out toward the edge. So when the temperature is low and humidity is high in air, this blower gives cool air to the base station without using air conditioner. Humidity= (air temperature/water temperature)*1003.3.4 Light dependent resistor The one more parameter which can be controlled in the base station is lighting process. We observe a high-intensity light indicating the presence of tower at the top of the tower i.e., near the lightning arrestor. This is also called aircraft warning light. This will be in on state irrespective of the light intensity of the atmosphere i.e., there is no need of that light to be in on-condition during day time. So, light dependent resistor is used to sense the light-intensity of the atmosphere. If intensity is greater than a predefined limit, the light will be switched off automatically. 3.4 DATA PROCESSING UNITIn the previous section, all the necessary data is acquired from different sensors and sensing circuits. Now all the collected input data is processed and converted to such a manner which is suitable for the processor and computer software.

Analog dataDigital dataSerial dataTo personal computer

Fig 3.14 Block diagram showing data conversion

3.4.1 Responder frequency to voltage conversion circuit

Calculating frequency from the time period every time is somewhat hard when compared to measuring the voltage. So, we convert frequency to voltage using IC LM331.LM331 is basically a precision voltage to frequency converter. The IC has a hand full of applications like analog to digital conversion, long term integration, voltage to frequency conversion, frequency to voltage conversion. Wide dynamic range and excellent linearity makes the IC well suitable for the applications mentioned above. Here the LM331 is wired as a frequency to voltage converter which converts the input frequency into a proportional voltage which is extremely linear to the input frequency. The frequency to voltage conversion is attained by differentiating the input frequency using capacitor C3 and resistor R7 and feeding the resultant pulse train to the pin6 (threshold) of the IC.

Fig 3.15Frequency to voltage converter circuit(LM331)3.4.2 PIC Microcontroller

Fig 3.16 Pin diagram of PIC micocontrollerMicrocontroller is a software driven electronics device. It is a single chip monolithic IC, which is designed by VLSI design technology. It will perform the arithmetic and logical operation with help of software. It is used to control and communicate the external peripherals. Here the PIC 16F877A microcontroller IC is used. It has inbuilt A/D converter. The A/D converter is required to our project because the transducer output is in the form of analog voltage signal. But the inside operation of microcontroller is digital. So we require A/D converter. It is 18 pin packages. The voltage range is 3.0 to 5.5V. The operating frequency of PIC 16F877A is 20MHz.FunctionsThe main functions of the microcontroller are: To receive the signal from the computer. Compare the signal with the standard strings stored in microcontroller Sends the output signal to the corresponding relaysOperationThe current images are compared with the reference images and corresponding output signal passed through serial port to MAX232. MAX232 IC converts it into TTL logic and then sends the signal to the microcontroller. The microcontroller is programmed using PIC Compiler using the software Embedded C. The microcontroller converts the signal to string format and compares with the standard strings and the output is given to the corresponding relaysMicrocontroller key features High Performance RISC CPU Only 35 single-word instructions to learn Operating speed: DC 20 MHz clock input; DC 200 ns instruction cycle. Up to 8K x 14 words of Flash Program Memory, Up to 368 x 8 bytes of Data Memory (RAM), Up to 256 x 8 bytes of EEPROM Data Memory Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation Interrupt Capability (up to 14 sources) Direct, Indirect and Relative addressing modes Low-power, high-speed Flash/EEPROM technology 100,000 erase/write cycle Enhanced Flash program memory typical 1,000,000 erase/write cycle Data EEPROM memory typical Data EEPROM Retention > 40 years Processor read/write access to program memory Wide operating voltage range (2.0V to 5.5V) Low Power Consumption3.4.3 RS-232 Serial communication is basically the transmission or reception of data one bit at a time. Today's computers generally address data in bytes or some multiple thereof. A byte contains 8 bits. A bit is basically either a logical 1 or zero. Every character on this page is actually expressed internally as one byte. The serial port is used to convert each byte to a stream of ones and zeroes as well as to convert streams of ones and zeroes to bytes. The serial port contains a electronic chip called a Universal Asynchronous Receiver/Transmitter (UART) that actually does the conversion.The most common communication interface for short distance is RS-232. RS-232 defines a serial communication for one device to one computer communication port, with speeds up to 19,200 baud. Typically 7 or 8 bits (on/off) signal are transmitted to represent a character or digit.The 9 pin connector is used. The pin details are given belowPINDESCRIPTION

1.Data carrier detect(DCD)

2.Received data(RxD)

3.Transmitted data(TxD)

4.Data terminal ready(DTR)

5.Signal ground(GND)

6.Data set ready(DSR)

7.Request to send(RTS)

8.Clear to send(CTS)

9.Ring Indicator(RI)

Table 3.17Pin description of RS-232 Fig.3.18DB-9 connectorWhen we look at the connector pin out of the RS232 port, we see two pins which are certainly used for flow control. These two pins are RTS, request to send and CTS, clear to send. With DTE/DCE communication (i.e. a computer communicating with a modem device) RTS is an output on the DTE and input on the DCE. CTS is the answering signal coming from the DCE. Before sending a character, the DTE asks permission by setting its RTS output. No information will be sent until the DCE grants permission by using the CTS line. If the DCE cannot handle new requests, the CTS signal will go low. Its a simple but useful mechanism allowing flow control in one direction. The assumption is that the DTE can always handle incoming information faster than the DCE can send it. In the past, this was true. Modem speeds of 300 baud were common and 1200 baud was seen as a high speed connection. For further control of the information flow, both devices have the ability to signal their status to the other side. For this purpose, the DTR data terminal ready and DSR data set ready signals are present. The DTE uses the DTR signal to signal that it is ready to accept information, whereas the DCE uses the DSR signal for the same purpose. Using these signals involves not a small protocol of requesting and answering as with the RTS/CTS handshaking. These signals are in one direction only. The last flow control signal present in DTE/DCE communication is the CD carrier detect. It is not used directly for flow control, but mainly an indication of the ability of the modem device to communicate with its counterpart. This signal indicates the existence of a communication link between two modem devices.3.4.4MAX 232The Max 232 is a dual RS-232 receiver / transmitter that meet all EIA RS232C specifications while using only a 5V power supply. It has 2 onboard charge pump voltage converters which generate +10V and 10V power supplies from a single 5V power supply. It has four level translators, two of which are RS232 transmitters that convert TTL\ CMOS input levels into + 9V RS232 outputs. The other two level translators are RS232 receivers that convert RS232 inputs to 5V TTL\CMOS output level. These receivers have a nominal threshold of 1.3V, a typical hysteresis of 0.5V and can operate upto + 30V input. 1. Suitable for all RS232 communications and +12V power supplies required.2. Voltage quadrapular for input voltage upto5.5V (used in power supply Section of computers, peripherals, and modems). Three main sections of MAX232 are 1. 5V to 10V dual charge pump voltage converter2. A dual transmitter3. A dual receiverFig 3.19 MAX 232 circuit(i) Power supply sectionThe MAX232 power supply section has 2 charge pumps the first uses external capacitors C1 to double the +5V input to +10V with input impedance of approximately 200. The second charge pump uses external capacitor to invert +10V to 10V with an overall output impedance of 45. The best circuit uses 22F capacitors for C1 and C4 but the value is not critical. Normally these capacitors are low cost aluminium electrolyte capacitors or tantalum if size is critical. Increasing the value of C1 and C2 to 47F will lower the output impedance of +5V to+10V doubler by about 5 and +10V to -10V inverter by about 10. Increasing the value of C3 and C4 lowers the ripple on the power supplies thereby lowering the 16 KHz ripple on the RS232 output. The value of C1 and C4 can be lowered to 1F in systems where size is critical at the expense of an additional impedance of 20 at +10V output and an additional impedance of 40 at 10V input. (ii) Transmitter sectionEach of the two transmitters is a CMOS inverter powered by 10V internally generated supply. The input is TTL and CMOS compatible with a logic threshold of about 26% of Vcc. The input if an unused transmitter section can be left unconnected: an internal 400K pull up resistor connected between the transistor input and Vcc will pull the input high forming the unused transistor output low.The open circuit output voltage swing is guaranteed to meet the RS232 specification 5v output swing under the worst of both transmitters driving the 3K. Minimum load impedance, the Vcc input at 4.5V and maximum allowable ambient temperature typical voltage with 5K and Vcc= .9 v. The slow rate at output is limited to less than 30V/s and the powered done output impedance will be a minimum of 300 with 2V applied to the output with Vcc =0V.The outputs are short circuit protected and can be short circuited to ground indefinitely. (iii) Receiver sectionThe two receivers fully conform to RS232 specifications. Theyre input impedance is between 3K either with or without 5V power applied and their switching threshold is within the +3V of RS232 specification. To ensure compatibility with either RS232 IIP or TTL\CMOS input. The MAX232 receivers have VIL of 0.8V and VIH of 2.4V the receivers have 0.5V of hysteresis to improve noise rejection.The TTL\CMOS compatible output of receiver will be low whenever the RS232 input is greater than 2.4V. The receiver output will be high when input is floating or driven between +0.8V and 30V.3.4.5 RF COMMUNICATION RF communication is used to transmit responder signal to switching of antennas using relays. The RF communication frequency is 433.92 MHZ which is cheap and reliable.Generally Radio frequency(RF) is a rate of oscillation in the range of around3KHzto300GHz, which corresponds to thefrequencyofradio waves, and thealternating currentswhich carry radio signals. Although radiofrequencyis a rate of oscillation, the term "radio frequency" or its abbreviation "RF" are also used as a synonym forradio i.e. to describe the use of wirelesscommunication, as opposed to communication via electric wires. RF is an alternating current which, if supplied to an antenna, will give rise to an electromagnetic field that propagates through space. How does an RF communication system work?

Imagine an RF transmitter wiggling an electron in one location. This wiggling electron causes a ripple effect, somewhat akin to dropping a pebble in a pond. The effect is an electromagnetic (EM) wave that travels out from the initial location resulting in electrons wiggling in remote locations. An RF receiver can detect this remote electron wiggling.The RF communication system then utilizes this phenomenon by wiggling electrons in a specific pattern to represent information. The receiver can make this same information available at a remote location; communicating with no wires.In most wireless systems, a designer has two overriding constraints: it must operate over a certain distance (range) and transfer a certain amount of information within a time frame (data rate). Then the economics of the system must work out (price) along with acquiring government agency approvals (regulations and licensing.RF CHARACTERISTICS Wireless communication technologyRF is an alternating current which, if supplied to an antenna, will give rise to an electromagnetic field that propagates through space. Cheap and widely usedOver 40 millions systems manufactured each year utilizing low-power wireless (RF) technology for data links, telemetry, control and security. However, once certified to comply with communication regulations, RF products do not require a license (air-time fee) for operation. Wide range of applicationsCordless and cellular telephones, radio and television broadcast stations, hand-held computer and PDA data links, wireless bar-code readers, wireless keyboards for PCs, wireless security systems, consumer electronic remote control, etc.To receive radio signals anantennamust be used. However, since the antenna will pick up thousands of radio signals at a time, aradio tuneris necessary totune intoa particular frequency (or frequency range).This is typically done via a resonator in its simplest form, a circuit with acapacitorand aninductorform atuned circuit. The resonator amplifies oscillations within a particularfrequency band, while reducing oscillations at other frequencies outside the band. Another method to isolate a particular radio frequency is byoversampling(which gets a wide range of frequencies) and picking out the frequencies of interest, as done insoftware defined radio.The distance over which radio communications is useful depends significantly on things other than wavelength, such as transmitter power, receiver quality, type, size, and height of antenna, mode of transmission, noise, and interfering signals.Ground waves,tropospheric scatterandsky wavescan all achieve greater ranges than line-of-sight propagation. The study ofradio propagationallows estimates of useful range to be made. Fig 3.20 RF moduleThese wireless receivers work with our 434MHz transmitters. They can easily fit into a breadboard and work well with microcontrollers to create a very simple wireless data link. Since these are only receivers, they will only work communicating data one-way, you would need two pairs (of different frequencies) to act as a transmitter/receiver pair.These modules are indiscriminate and will receive a fair amount of noise. Both the transmitter and receiver work at common frequencies and don't have IDs. Therefore, a method of filtering this noise and pairing transmitter and receiver will be necessary. The example code below shows such an example for basic operation. Please refer to the example code and links below for ways to accomplish a robust wireless data link.Features 434 MHz 500ft range (given perfect conditions) 4800bps data rate 5V supply voltageAs with any other radio-frequency device, the performance of an RF module will depend on a number of factors. For example, by increasing the transmitter power, a larger communication distance will be achieved. However, this will also result in a higher electrical power drain on the transmitter device, which will cause shorter operating life for battery powered devices. Also, using a higher transmit power will make the system more prone to interference with other RF devices, and may in fact possibly cause the device to become illegal depending on the jurisdiction. Correspondingly, increasing the receiver sensitivity will also increase the effective communication range, but will also potentially cause malfunction due to interference with other RF devices. The performance of the overall system may be improved by using matched antennas at each end of the communication link, such as those described earlier.Finally, the labeled remote distance of any particular system is normally measured in an open-air line of sight configuration without any interference, but often there will be obstacles such as walls, floors, iron construction to absorb the radio wave signals, so the effective operational distance will in most practical instances be less than specified.RF module features433MHz Super heterodyne 3400 RF Transmitter and Receiver

Transmitter Specifications

Working voltage:3V~12VWorking current:max40mA (12V), min9mA (3V)Resonance mode:sound wave resonance (SAW)Modulation mode:ASK /OOKWorking frequency:315MHz-433.92MHz, customized frequency is available.Transmission power:25mW (315MHz at 12V)Frequency error:+150kHz (max)Velocity:10KbpsSelf-owned codes:negativeAerial Length:24cm (315MHz), 18cm(433.92MHz)Dimensions:43x12x5mmWeight:2g

Receiver Specifications

Working voltage:5.0VDC +0.5VWorking current:2.5mA (5.0VDC)Working principle:super heterodyneWorking method:OOK/ASKOperating frequency:315MHz, 433.92MHz, customized frequency is available;Bandwidth:2MHz (315MHz, having result from testing at lowing the sensitivity 3dBm)Sensitivity:excel 105dBm (50)Output signal:TTL electric level signal entire transmitDimensions:19x12x5.5mmWeight:1.6g

3.4.6 Hybrid boardSolar energy and wind energy are the real and unpolluted energy forever. Demand of electrical energy and less availability of present resources ,we need to develop a system which will be efficient to produce more electrical energy by accepting natural resources like sunlight, wind etc.In this project, we would like to introduce hybrid technology to generate power using renewable resources such as wind and solar .The energy resources solar and wind are seasonal, both may not be available at all times which causes an interruption in the power are flow thus reducing the efficiency and consistency in the power. So,we are combining both solar energy and wind energy to form hybrid power as shown in above figure which results in power saving of this green radio technology.CHAPTER 4 HARDWARE AND SOFTWARE REQUIREMENTS4.1HARDWARE REQUIREMENTS:4.1.1 PIC 16F877A Microcontroller:PICis a family ofmodified Harvard architecturemicrocontrollers made byMicrochip Technology, derived from the PIC1650originally developed byGeneral Instrument's Microelectronics Division. The name PIC initially referred to "Peripheral Interface Controller'" now it is "PIC'" only.PICs are popular with both industrial developers and hobbyists alike due to their low cost, wide availability, large user base, extensive collection of application notes, availability of low cost or free development tools, and serial programming (and re-programming with flash memory) capability.

Fig 4.1 PIC Microcontroller

The characteristics of PIC microcontroller is tabulates as follows:Parameter nameValue

Program memory typeFlash

Program memory(Kb)14

CPU Speed (MIPS)5

RAM(bytes)368

Data EEPROM (bytes)256

Digital communication peripherals1-UART,1-USART,1-SPI

Timers2X8 bit,1X16 bit

ADC8 channel,10 bit

Comparators2

Temparature range(c)-40 to125

Operating voltage range(v)2 to 5.5

Pin count40

Table 4.2 PIC characteristicsAdvantages of PIC . It is a RISC (Reduced Instruction Set computer) design. Its code is extremely efficient, allowing PIC to run with typically less program memory than its larger competitors. It is low cost, high clock speed4.1.2 ThermistorsA thermistor is an input transducer (sensor) which converts temperature (heat) to resistance. Almost all thermistors have a negative temperature coefficient (NTC) which means their resistance decreases as their temperature increases. It is possible to make thermistors with a positive temperature coefficient (resistance increases as temperature increases) but these are rarely used. Always assume NTC if no information is given Fig 4.3 Circuit symbol for thermistor &examplesA multimeter can be used to find the resistance at various temperatures; these are some typical readings for exampleIcy water 0C: high resistance, about 12k.Room temperature 25C: medium resistance, about 5k.Boiling water 100C:low resistance, about 400.Suppliers usually specify thermistors by their resistance at 25C (room temperature). Thermistors take several seconds to respond to a sudden temperature change, small thermistors respond more rapidly. A thermistor may be connected either way round and no special precautions are required when soldering. If it is going to be immersed in water the thermistor and its connections should be insulated because water is a weak conductor.For example they could be coated with polyurethane varnish.4.1.3 Light dependent resistorAn LDR is an input transducer (sensor) which converts brightness (light) to resistance. It is made from cadmium sulphide (CdS) and the resistance decreases as the brightness of light falling on the LDR increases.

Fig 4.4 Circuit Symbol for LDR& exampleA multimeter can be used to find the resistance in darkness and bright light; these are the typical results for a standard LDR Darkness: maximum resistance, about 1M. Very bright light: minimum resistance, about 100. For many years the standard LDR has been the ORP12, now the NORPS12, which is about 13mm diameter. Miniature LDRs are also available and their diameter is about 5mm. An LDR may be connected either way round and no special precautions are required.4.1.4 Relays

Arelayis anelectrically operatedswitch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such assolid state relays. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distancetelegraphcircuits as amplifiers, they repeated the signal coming in from one circuit and re-transmitted it on another circuit.

Fig 4.5: Relay and its symbolAs we know relay is a device which is used to provide connection between two or more points or device in response to the input signal applied. In another words relay provide isolation between the controller and the device as we know devices may work on AC as well as on DC. However, they receive signals from microcontroller which works on DC hence we require a relay to bridge the gap. Relay is extremely useful when you need to control a large amount of current or voltage with small electrical signal.

Fig 4.6 Relay and its partsParts of relaysThere are 5 parts in every relay. They are as follows:1.Electromagnet- It consists of iron core wounded by coil of wires. When electricity is passed through it become magnetic therefore it is called as electromagnet.2.Armature-The movable magnetic strip is known as armature. When current flowsthrough them, it energizes thecoil and produce magnetic field which is used to make or break the normally open (N/O) or normally close (N/C) points. Armature can be moved with direct current (DC) as well as alternating current (AC).3.Spring- When no current flow through coil electromagnet, the spring pulls the armature away so that circuit cannot be completed.4.Set of electrical contacts- There are two contact points .They are: a. Normally open-In this the device connected to it will work when relay is activated and disconnect it when relay is inactive. b. Normally close- In this the device connected to it will not work when relay is activated and the circuit is connected when relay is inactive.5.Molded frame-Relays are covered with plastic or glass so that we can observe its working without opening or removing its coverWorking of Relay Working of relay is simple, when power is supplied to relay current start flowing through the control coilas a result electromagnetic starts energizing. Hear points A,B,C are used as control points. When power is applied to input terminal due to electromagnetic effect, B and C are connected thus closes the contacts causing a short circuit for the power to the load. If the relay was already de-energized when the contacts were closed, then thecontact move opposite and make an open circuit. When power supply is cut off point A and C are connected. This force is mainly provided by two factors they are spring and gravity.

Fig 4.7 Working of relayDifferent Types of Relay1. Single Pole Single Throw (SPST): these types of relay comprise of 4 terminals. Two terminals are used as coil points and other two can be used to connect or disconnect the circuit (A and B).2. Single Pole Double Throw (SPDT): these types of relay comprise of 5 terminals two for coil one for common terminal(C) and rest two can be connected to the common terminal.3. Double Pole Single Throw (DPST): these types of relay comprise of 6 terminal two for coil and other four for connecting and disconnectingtwo device. In other words it contains two SPST relay in one package.4.DoublePole Double Throw(SPDT): these types of relay comprise of 8 terminal two for coil and another two as common point and rest for connecting and disconnecting devices. In another words in this two SPDT relay are connected in one package.

Fig 4.8 Types of relaysApplication of relaysRelays were used extensively in telephone exchanges and early computers to perform logical operations.4.1.5 Solar panelAsolar panelis a set of solar photovoltaicmodules electrically connected and mounted on a supporting structure. A photovoltaic module is a packaged, connected assembly ofsolar cells. The solar panel can be used as a component of a larger photovoltaic system to generate and supplyelectricityin commercial and residential applications. Each module is rated by itsDCoutput power under standard test conditions (STC),and typically ranges from 100 to 320 Watts.

Fig 4.9 Solar PanelTheefficiency of a module determines the area of a module given the same rated output - an 8% efficient 230 watt module will have twice the area of a 16% efficient 230 watt module.4.1.6 Wind turbineAwind turbineis a device that convertskinetic energyfrom thewind into electric power. A wind turbine used for charging batteries may be referred to as awind charger.The result of over a millennium of windmill development and modern engineering, today's wind turbines are manufactured in a wide range of vertical and horizontal axis types. The smallestturbinesare used for applications such as battery charging for auxiliary power for boats or caravans or to power traffic warning signs. Slightly larger turbines can be used for making small contributions to a domestic power supply while selling unused power back to the utility supplier via theelectrical grid. Arrays of large turbines, known aswind farms, are becoming an increasingly important source ofrenewable energy and are used by many countries as part of a strategy to reduce their reliance onfossil fuels.

Fig 4.10 Wind turbine

4.1.7 TransformerAtransformeris an electrical device that transfers energy between two circuits throughelectromagnetic induction. A transformer may be used as a safe and efficientvoltage converter to change the AC voltage at its input to a higher or lower voltage at its output. Other uses include current conversion, isolation with or without changing voltage andimpedance conversion. Fig 4.11 Symbol for transformerBasic principleThe operation of a transformer is based on two principles of the laws of electromagnetic induction: An electric current through a conductor, produces amagnetic field surrounding the conductor, and a changing magnetic field in the vicinity of a conductor induces a voltage across the ends of that conductor.The magnetic field excited in the primary coil gives rise to self-induction as well as mutual induction between coils. This self-induction counters the excited field to such a degree that the resulting current through the primary winding is very small when the secondary winding is not connected to a load.

Fig 4.12 step down transformerThe invention of transformers during the late 1800s enabled long distance, cheaper, and energy efficienttransmission,distribution, and utilization ofelectrical energy. In the early days of commercial electric power, the main energy source was direct current (DC), which operates at relatively low voltage and high-current.

Fig 4.13 Example for transformerAccording toJoule's Law, energy losses are directly proportional to the square of the current. This law revealed that even a tiny decrease in current or rise in voltage can cause a substantial lowering in energy losses and costs. Thus, the historical pursuit for a high voltage low current electricity transmission system took shape. Although high voltage transmission systems offered many benefits, the future fate of high-voltage alternating current remained unclear for several reasons: high-voltage sources had a much higher risk of causing severe electrical injuries. Many essential appliances could only function at low voltage. Regarded as one of the most influential electrical innovations of all time, the introduction of transformers had successfully reduced the safety concerns associated with alternating current and had the ability to lower voltage to the value required by most essential appliances.A transformer most commonly consists of two windings of wire that are wound around a common core to provide tight electromagnetic coupling between the windings. The core material is often a laminatediron core. The coil that receives the electrical input energy is referred to as the primary winding, the output coil is the secondary winding.An alternatingelectric currentflowing through the primary winding (coil) of a transformer generates a varying electromagnetic field in its surroundings which induces a varyingmagnetic fluxin the core of the transformer. The varying electromagnetic field in the vicinity of the secondary winding induces anelectromotive forcein the secondary winding, which appears as avoltageacross the output terminals. If a load is connected across the secondary winding, a current flows through the secondary winding drawing from the primary winding and its current source.

Fig 4.14 Operation of transformerA transformer cannot operate with direct current. When connected to a DC source, a transformer typically produces a short output pulse as the input current rises.Applications of transformer Transformers performvoltage conversion,isolation protection, andimpedance matching. In terms of voltage conversion, transformers can step up voltage and step down current from generators to high voltage transmission lines, and step down voltage/step up current to local distribution circuits or industrial customers. The step-up transformer is used to increase the secondary voltage relative to the primary voltage. The step-down transformer is used to decrease the secondary voltage relative to the primary voltage. Transformers range in size from thumbnail-sized units used in microphones to those weighing hundreds of tons interconnecting thepower grid. A broad range oftransformer designs are used in electronic and electric power applications, including miniature, audio, isolation, high-frequency, power conversion, etc.4.1.8 ResistorsResistance is measured in ohms; the symbol for ohm is an omega. 1 is quite small so resistor values are often given in k and M. 1 k = 1000 1 M = 1000000.

ColorNumber

Black0

Brown1

Red2

Orange3

Yellow4

Green5

Blue6

Violet7

Grey8

White 9 Fig4.15 Color coding for resistorsMost resistors have 4 bands: The first band gives the first digit. The second band gives the second digit. The third band indicates the number of zeros. The fourth band is used to shows the tolerance (precision) of the resistor, this may be ignored for almost all circuitFor example

This resistor has red (2), violet (7), yellow (4 zeros) and gold bands. So its value is 270000 = 270 k. On circuit diagrams the symbol is usually omitted and the value is written 270K. Small value resistors (less than 10 ohm)The standard color code cannot show values of less than 10. To show these small values two special colors are used for the third band: gold which means 0.1 and silver which means 0.01. The first and second bands represent the digits as normal. For example:red, violet, gold bands represent 270.1=2.7green, blue, silver bands represent 560.01=0.56Tolerance of resistors (fourth band of color code)The tolerance of a resistor is shown by the fourth band of the color code. Tolerance is the precision of the resistor and it is given as a percentage. For example a 390 resistor with a tolerance of 10% will have a value within 10% of 390, between 390 - 39 = 351 and 390 + 39 = 429 (39 is 10% of 390). A special color code is used for the fourth band tolerance:silver 10%, gold 5%, red 2%, brown 1%. If no fourth band is shown the tolerance is 20%. Tolerance may be ignored for almost all circuits because precise resistor values are rarely required. 4.1.9 CapacitorsCapacitors store electric charge. They are used with resistors in timingcircuits because it takes time for a capacitor to fill with charge. They are used to smooth varying DC supplies by acting as a reservoir of charge. They are also used in filter circuits because capacitors easily pass AC (changing) signals but they block DC (constant) signals. This is a measure of a capacitor's ability to store charge. A large capacitance means that more charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very large, so prefixes are used to show the smaller values. Three prefixes (multipliers) are used, (micro), n (nano) and p (pico): means 10-6 (millionth), so 1000000F = 1F n means 10-9 (thousand-millionth), so 1000nF = 1F p means 10-12 (million-millionth), so 1000pF = 1nF Capacitor values can be very difficult to find because there are many types of capacitor with different labeling systems. There are many types of capacitor but they can be split into two groups, polarized and unpolarized. Each group has its own circuit symbol. Polarized capacitors (large values, more than 1F) Fig 4.16 Circuit symbol for polarized capacitorsElectrolytic Capacitors:Electrolytic capacitors are polarized and they must be connected the correct way round, at least one of their leads will be marked + or -. They are not damaged by heat when soldering. There are two designs of electrolytic capacitors; axial where the leads are attached to each end (220F in picture) and radial where both leads are at the same end (10F in picture). Radial capacitors tend to be a little smaller and they stand upright on the circuit board. It is easy to find the value of electrolytic capacitors because they are clearly printed with their capacitance and voltage rating. The voltage rating can be quite low (6V for example) and it should always be checked when selecting an electrolytic capacitor. If the project parts list does not specify a voltage, choose a capacitor with a rating which is greater than the project's power supply voltage. 25V is a sensible minimum for most battery circuits. Un polarized capacitors (small values, up to 1F)

Fig4.17 Unpolarized capacitors and its symbolSmall value capacitors are unpolarized and may be connected either way round. They are not damaged by heat when soldering, except for one unusual type (polystyrene). They have high voltage ratings of at least 50V, usually 250V or so. It can be difficult to find the values of these small capacitors because there are many types of them and several different labeling systems. Many small value capacitors have their value printed but without a multiplier, so you need to use experience to work out what the multiplier should be.

Fig4.18 Example for capacitorFor example 0.1 means 0.1F = 100nF. Sometimes the multiplier is used in place of the decimal point.For example: 4n7 means 4.7nF.

4.1.10 DiodesDiodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve and early diodes were actually called valves.

Fig4.19 Circuit symbol & examplesForward Voltage DropElectricity uses up a little energy pushing its way through the diode, rather like a person pushing through a door with a spring. This means that there is a small voltage across a conducting diode, it is called the forward voltage drop and is about 0.7V for all normal diodes which are made from silicon. The forward voltage drop of a diode is almost constant whatever the current passing through the diode so they have a very steep characteristic (current-voltage graph).

Fig4.20 Characteristics of silicon diodeReverse VoltageWhen a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a very tiny current of a few A or less. This can be ignored in most circuits because it will be very much smaller than the current flowing in the forward direction. However, all diodes have a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail and pass a large current in the reverse direction, this is called breakdown. Ordinary diodes can be split into two types: Signal diodes which pass small currents of 100mA or less and Rectifier diodes which can pass large currents. In addition there are LEDs and Zener diodes. Rectifier diodes are quite robust and no special precautions are needed for soldering them.Zener diodesZener diodes are used to maintain a fixed voltage. They are designed to 'breakdown' in a reliable and non-destructive way so that they can be used in reverse to maintain a fixed voltage across their terminals. The diagram shows how they are connected, with a resistor in series to limit the current.

Fig4.21 zener diode circuit symbol & examplesZener diodes can be distinguished from ordinary diodes by their code and breakdown voltage which are printed on them. Zener diode codes begin BZX... or BZY... Their breakdown voltage is printed with V in place of a decimal point, so 4V7 means 4.7V for example.

Fig 4.22 zener diode as a voltage regulator

Zener diodes are rated by their breakdown voltage and maximum power: The minimum voltage available is 2.4V. Power ratings of 400m and 1.3W are common. 4.1.11 Light emitting diode (LED)LEDs emit light when an electric current passes through them.

Fig 4.23 LED exampleLEDs must be connected the correct way round, the diagram may be labeled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode). The cathode is the short lead and there may be a slight flat on the body of round LEDs. If you can see inside the LED the cathode is the larger electrode (but this is not an official identification method). LEDs can be damaged by heat when soldering, but the risk is small unless you are very slow. No special precautions are needed for soldering most LEDs.4.1.12 Voltage regulatorVoltage regulators are responsible for maintaining a steady voltage across an electronic system .Voltage fluctuations may result in undesirable effect on an electronic system, so maintaining a steady and constant voltage is necessary according to the voltage requirement of the system.Let us assume a condition when a simple LED can take a maximum of 3v,the diode burn out definitely .This will be common for all electronic components like LEDs, Capacitors ,Diodes etc,. The slightest increase in voltage may result in the failure of entire system by damaging the other components .To avoid such situations we use voltage regulator for regulated power supply.7805 IC 7805 is a series of 78XX voltage regulators. Its a standard, from the name the last two digits 05 denotes theamount ofvoltage that it regulates. Hence a 7805 would regulate 5v and 7806 would regulate 6V and so on.

Fig4.24 7805 voltage regulatorIC 7805 is a 5v voltage regulator that restricts the output voltage to 5v and draws 5v regulated power supply. It comes with provision to add heat sink. The maximum value for input to the voltage regulator is 35V. It can provide a constant steady voltage flow of 5V for higher voltage input till the threshold limit of 35V. If the voltage is near to 7.5V then it does not produce any heat and hence no need for heat sink. If the voltage input is more, then excess electricity is liberated as heat from 7805.It regulates a steady output of 5V if the input voltage is in range of 7.2V to 35V. Hence to avoid power loss try to maintain the input to 7.2V. In some circuitry voltage fluctuation is fatal (for e.g. Microcontroller), for such situation to ensure constant voltageIC 7805 Voltage Regulatoris used.The schematic given shown above that how to use a 7805 IC, there are 3 pins in IC 7805, pin 1 takes the input voltage and pin 3 produces the output voltage. The GND of both input and out are given to pin2.Pin NOFunctionName

Input VoltageInput voltage (5V-18V)Input

GroundGround (0V)Ground

Regulated OutputRegulated output(4.8-5.2)vOutput

Table 4.1 7805 pin functions

7812The 78xx is a family of self-contained fixedlinear voltage regulatorintegrated circuits.The 78xx family is commonly used in electronic circuits requiring a regulated power supply due to their ease-of-use and low cost.For ICs within the family, thexxis replaced with two digits, indicating the outputvoltage.For example while the 7812 produces 12Volts.The 78xxline are positive voltage regulators: they produce a voltage that is positive relative to a common ground.Fig4.25 7812 voltage regulator78xx ICs have three terminals and are commonly found in theTO220form factor, although smaller surface-mount and largerTO3packages are available. These devices support an input voltage anywhere from a few Volts over the intended output voltage, up to a maximum of 35 to 40Volts depending on the make, and typically provide 1 or 1.5amperes ofcurrent(though smaller or larger packages may have a lower or higher current rating.Advantages of voltage Regulators 78xx series ICs do not require additional components to provide a constant, regulated source of power, making them easy to use, as well as economical and efficient uses of space. Other voltage regulators may require additional components to set the output voltage level, or to assist in the regulation process. Some other designs (such as switched mode power supply)may need substantial engineering expertise to implement. 78xx series ICs have built-in protection against a circuit drawing too much power. They have protection against overheating and short-circuits, making them quite robust in most applications. In some cases, the current-limiting features of the 78xx devices can provide protection not only for the 78xx itself, but also for other parts of the circuit791279xxdevices which are complementary negative voltage regulators. 78xx and 79xx ICs can be used in combination to provide positive and negative supply voltages in the same circuit.It produces negative 12 volts regulated voltage as output.

Fig 4.26 7912 voltage regulator

4.2 SOFTWARE REQUIREMENTS4.2.1 Introduction to visual basicThe Microsoft VB programming system for windows is an exciting advance for anyone who is involved in writing window base applications. With this event driven programming engine and innovative, easy to use visual design tools, VB lets you take full advantage of the window graphical environment to built powerful application quickly.As more people began to use computers the isotonic and complicated languages used for programming became more of an obstacle. A language called BASIC was developed to counteract this. Its simplicity made it easy for the users to write amazing programs.Over the years this programming language was enhanced and developed. The demand for faster, simpler, smaller and easy to use software led to the development of Microsoft quick Base. This was in line with the programming language technology of the 1980s but an even bigger change was on the horizon namely, graphical user interface (GUI).With the advent of windows, users are able to work in a graphically rich environment. This made application much easier to learn and use. It also facilitated the use of multiple windows on the screen enabling to run more than one program at a time.Although this environment was like a boon to the user, life was suddenly a lot together for programmers. A simple program to display a message on the screen, which could be written in four lines in MSDOS, now, ran to two or three pages.Programming for window with visual basicThe VB programming system packages up the complexity of windows in a truly amazing way. It provides simplicity and ease of use without sacrificing performance or the graphical features that make window such a pleasant environment to work in Menus, fonts, dialog, boxes etc are easily designed and these features require no more than a few lines of programming to control.It is one of the first languages to support event driven programming a style of program especially suited to graphical user interface. The aim in modern computer application is to have the user in charge.Instead of writing a program that plots out every step in precise order, the programmer writes a program that responds the users action like choosing a command, moving the mouse etc. Instead of writing on large program, the programmer creates an application, which is a collection of co operating many programs. With VB such an application can be written with unprecedented speed and case.FEATURES A data base creation tool Visual data access with the data control so that it is possible to create data browsing application without writing code. A new OLE (object linking and embedding) control that allows in place editing. A collection of common dialog boxes that streamline common user interface tasks. The ability to create pop-up menus anywhere in the application

RESULTSThe figure represents the green radio kit which consists of signal conditioning board, PIC microcontroller board, relay board, RF transmitter, Hybrid board which is used for controlling the antennas in base stations by sensing different inputs such as temperature, humidity, light intensity, mainly user capacity. And the responder signal for switching is transmitted using RF transmitter.

The figure represents RF receiver board which contain relay driver, transformer, RF module which is used to receive the responder signal for antenna switching using relays.

The figure represents the wind turbine which is used to generate power.

SIMULATION RESULTSInitially when none of the tower is in operation, the power amplifier will be in off state, there will not be any signal transmission to remote tower and both the cooling unit and lighting unit will be in OFF state.

When the responder frequency is sent from the first tower to the second tower the amplifier get turned ON.

If the user capacity increases rapidly, then the responder frequency again sends to next tower which also handles the users to satisfy mobile users.

By sensing the temperature and light intensity and depending upon the condition they are turned ON and OFF

CONCLUSIONIt can be seen that increase in mobile users leads to increase in power consumption, which in turn leads to emission of more and more CO2. This leads to global warming as CO2 is considered to be one of the green house gases. In order to control this effect, the major area to be controlled is to reduce power consumption. This can be reduced by taking various parameters into account such as the operation of Air Conditioner, cooling fan, light indicator and power amplifier. This project has aimed at reducing the power consumption by taking these parameters into account and the outcome has been positive. As per the objective, energy consumption will be reduced as much as possible and hence the emission of harmful green house gases will be reduced. This leads to an environmental friendly approach towards wireless communication. This has already been implemented in countries like the United Kingdom. United kingdom was the first country to implement this technology and the results were positive. FUTURE SCOPEThis technology has huge scope of improvement in future, which will lead to fully implemented GREEN technology. Various other techniques of green radio technology like network topology restructuring, antenna design, switching technique used, transmitter and receivers used, communication techniques can all be combined together to achieve complete energy-efficient communication system. To start with, the leading way is with solar energy. It is powering mobile towers with solar photo voltaic cells in remote rural India. The Solar Photo Voltaic uses sunlight to generate electricity thus eliminating dependency on grid power and diesel. This is a standalone system which can be installed on site. The installation process is easy and once installed the equipment needs almost zero maintenance, keeping operating costs at a minimum. Its lifespan of 25 years provides the site with a stable and permanent source of power, minus noise pollution or toxic emissions. On an average, installation of solar photo voltaic cells can lead to reduction of 2.5 tons of CO2 emission per tower every year.

REFERENCES1. Nasir Faruk and Mujahid Y. Muhammad (2012) Energy Conservation through Site Optimization for Mobile Cellular Systems (Base Transceivers Station Optimization) Epistemic in Science, Engineering and Technology, Vol.2, No.12. C. Lubritto and A. Petragliaa (2011) Energy and environmental aspects of mobile communication systemsEnergy, Volume 36, Issue 2, pp 1109-1114.3. Pete Boyer, Milica Stojanovic, and John Proakis, October (2001) A Simple Generalization of the CDMA Reverse Link Pole Capacity Formula IEEE Transactions on Communications VOL. 49, NO. 10 pp17194. Niranjan Balasubramanian, Aruna Balasubramanian and Arun VenkataramaniEnergy Consumption in Mobile Phones: A MeasurementStudy and Implications for Network ApplicationsCopyright 2009 ACM 978-1-60558-770-7/09/11 IMC09, November 46, 2009, Chicago, USA5. Green Radio Towards Sustainable Wireless Networks 8th July 2010 Steve McLaughlin University of Edinburgh6. Study on Energy Efficient Radio Access Network (EERAN) Technologies, 2009 Project Report of Technical University of Dresden, Vodafone Chair Mobile Communication Systems. 7. T. Edler, Green Base Stations How to Minimize CO2 Emission in Operator Networks, Ericsson seminar, Bath Base Station Conf., 2008.8. P. Wright et al., A Methodology for Realizing High Efficiency Class-J in A Linear and Broadband PA, IEEETrans. Microwave Theory and Techniques, vol. 57, 2009, pp. 31963204.WEBSITES1. http://indiatoday.intoday.in/story/cell-phone-tower-carbon-emissions-worries-trai/1/129212.html2. http://www.circuitsfinder.com/basic/Remote_Control_Circuit_Through_RF_Without_Microcontroller_617.html

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