The Use Of Engines Powered By Gasoline - 1592 Words

Plan of Investigation At the turn of the 20th Century, the advent of a number of new technologies posed to change the economy and society of the United States. One such technology was the internal combustion engine, which, after the last 100 years of common use, can be considered one of the most influential technologies of the 20th century. The rapid rise in the use of engines powered by gasoline is commonly attributed to the popularity of the â€Å"Model T† car introduced by Henry Ford in 1908. Prior to this, the combustion engine faced serious competition from steam and electric engines. In order to ascertain why the Model T was so successful compared to other vehicles of the time, I plan to analyze aspects of American society in the early†¦show more content†¦In comparison, while the earliest design of combustion engines can be dated back to 1680, no practical designs were actually built by 1858. In his autobiography, Henry Ford himself makes accounts of the hesitance with which the adv ent of combustion engines were met, in favor of steam and electric engines. On the subject of the emergence of gas engines, he recalls that â€Å"They were received with interest rather than enthusiasm and I do not recall any one who thought that the internal combustion engine could ever have more than a limited use. All the wise people demonstrated conclusively that the engine could not compete with steam.† The time period during which the Model T’s rise to popularity took place must also be considered. From 1890 to 1920, a period of American progression aptly named the â€Å"Progressive Era† took place. Beginning as a social movement and developing into a political agenda, Progressivism refuted Social Darwinism and asserted that society’s problems, namely such issues as poverty, racism, and class warfare, could be solved by improving education, environments, and workplaces. In general, progressives believed that all people had the right to the core aspe cts of democracy that promoted independence. Evidence suggests that the availability of an automobile to the masses brought such a

The Secret of Ella and Micha Chapter 10 Free Essays

string(29) " her shirt to pull her down\." Ella I can remember the first time I wanted to kiss Micha as clearly as the day I found my mother dead. Both times were equally as terrifying, but in two different ways. Micha and I had been sitting on the hood of his car at our secret spot tucked away in the trees, staring out at the lake. We will write a custom essay sample on The Secret of Ella and Micha Chapter 10 or any similar topic only for you Order Now It was harder than hell to get back to the spot, but the view and serenity made it worth it. It had been quiet between the two of us for a while, which was normal except for the jealousy stirring inside me over Micha’s latest hook up, Cassandra. I’d never felt this way before and it puzzled me. It wasn’t like the girl was anything special to Micha, but he’d told Ethan that she had the potential to be girlfriend material and it was bugging me. Micha’s arms were tucked under his head and his eyes were shut as the sunlight beamed down on him. His shirt had ridden up and I could see his tattoo peeking out. As I stared at it the urge to run my fingers along it drove me crazy. â€Å"I don’t like Cassandra,† I abruptly sputtered out, sitting up quickly. Micha’s eyebrows knitted as his eyes gradually opened against the sunlight. â€Å"Huh?† â€Å"That Cassandra girl you were talking about the other day,† I said, staring out at the water rippling in the gentle breeze. â€Å"I don’t think you should date her.† He rose up on his elbows. â€Å"Because you don’t like her?† â€Å"No†¦Ã¢â‚¬  I tucked strands of my auburn hair out of my eyes. â€Å"I just don’t want you to date her.† The wind filled the silence. Micha sat up and wrapped an arm around my shoulder. â€Å"Okay, I won’t,† he said as if it was as simple as breathing. I pressed back a smile, not fully understanding why the hell I was so happy. Micha lay back down and drew me with him. I rested my head on his chest and listened to his heart beating, steady as a rock, unlike mine which was dancing inside my chest. The longer I stayed in his arms, the more content I became. I felt safe, like nothing could hurt me, but I was in complete denial that I was starting to fall in love with my best friend. *** It’s been a week since the car racing incident and I’ve been hiding out in my bedroom living on mac n’ cheese and Diet Dr. Pepper. Dean still hasn’t headed home, but Lila did the morning after the race. She wanted to stay, but I didn’t want her to and I think her dad wasn’t too keen on the idea either. It’s been kind of lonely, though. I still haven’t listened to Micha’s voicemail, and the constant flashing on the screen torments me. I decide to take a break from the house today and do something I’ve been meaning to do for a while. I want to sketch my mother’s grave because I won’t always be close enough to visit it. It’s been bothering me the entire eight months that I’ve been gone. I feel guilty because it was me who put her there and then I just left her. I collect my sketch book and pencils from the drawer of my night stand, slip on my shoes and sunglasses, and head out the front door where I’m less likely to run into Micha. It’s a warm day and the blue sky glitters with sunshine. I walk up the sidewalk toward Cherry Hill and decide to make a last minute stop at Grady’s. I knock on the trailer door and Amy, the nurse, answers it wearing blue scrubs. â€Å"Oh, hi Ella, I don’t think Grady’s up for any visitors today, sweetie.† â€Å"But he told me to stop by,† I say stupidly. â€Å"I know it’s a little later than I told him and I’m sorry.† â€Å"He’s not mad at you, Ella,† she says kindly. â€Å"I’ve just got him hooked up on oxygen and he’s got a cough.† I shield my eyes from the sun and stare up at her. â€Å"Is he okay?† She sighs, leaning against the doorframe. â€Å"He’s just having a rough day today, but try back in a few days, okay hun.† I nod and back down the steps as she shuts the door. I stare helplessly at the back window which leads to Grady’s room. He’s sick and there’s nothing I can do. I have no control over this. Micha was right. I can’t control everything. As horrid images of my mom’s death flash through my mind, I run into the field and throw up. *** The town’s cemetery is located up on Cherry Hill, which on foot is quite a hike, but I enjoy the break from the reality of life. There is no one up there – there hardly ever is. I push through the gate and situate by a tree right in front of my mom’s headstone. It’s a small cemetery bordered by trees and the grass is covered with dry leaves. As I sketch the lines of the fence and the vines that coil it, I angle downward and draw the curve of her tombstone. I become lost in the movements, adding wings to the side of it, because she was always so fascinated with flying. A few weeks before her death, my mother begged me to go on a walk with her. I gave in even though I had plans that day. It was sunny and the air smelled like cut grass. It felt like nothing could go wrong. She wanted to go to the bridge so we walked all the way across town to the lake. When we arrived there, she climbed on the railing and spread her hands out to balance as her long auburn hair flapped in the wind. â€Å"Mom, what are you doing?† I said, reaching for the back of her shirt to pull her down. You read "The Secret of Ella and Micha Chapter 10" in category "Essay examples" She sidestepped down the railing out of my reach and stared at the water below. â€Å"Ella May, I think I can fly.† â€Å"Mom, stop it and get down,† I said, not taking her very seriously at first. But when she turned her head and looked at me, I could see in her eyes that she wasn’t joking. She really believed she could fly. I tried to stay as composed as possible. â€Å"Mom, please get down. You’re scaring me.† She shook her head and her legs wobbled a little. â€Å"It’s okay honey. I’ll be fine. I can feel it in my body that I can fly.† I took a cautious step toward her and my foot bumped the curb of the bridge. The cement rubbed my toe raw and I could feel blood oozing out, but I didn’t look down at it. I was too afraid to take my eyes off her. â€Å"Mom, you can’t fly. People can’t fly.† â€Å"Then maybe I’m a bird,† she said seriously. â€Å"Maybe I have wings and feathers and they can carry me away and I can become one with the wind.† â€Å"You’re not a bird!† I shouted and reached for her again, but she hopped onto one of the beams and laughed like it was a game. I tugged my fingers through my hair and steadied onto the railing. It was a far fall, one that would crush our bodies on impact, even in the water. I braced my hands on the beams above my head. â€Å"Mom, if you love me at all, you’ll get down.† She shook her head. â€Å"No, I’m going to fly today.† A truck rolled up and stopped on the middle of the bridge as I edged toward her. Ethan jumped out and didn’t so much as flinch at the scenario. â€Å"Hey, Mrs. Daniels. How’s it going?† I gaped at him and hissed, â€Å"What are you doing?† He ignored me. â€Å"You know it’s not really safe out there.† My mom angled her head to the side. â€Å"I think I’ll be okay. My wings will carry me away.† I was mortified, but Ethan didn’t miss a beat. He rested his arms on the railing. â€Å"As much as that could be true, what if it’s not? Then what? I mean is it really worth the risk?† I glanced back at my mom and she looked like she was weighing the options. She stared at the dark water below her feet and then at the bright sky above her head. â€Å"Maybe I should think about it for a little bit.† Ethan nodded. â€Å"I think that’s probably a good idea.† She made a path across the beam and planted her feet on the railing. Ethan helped her down and we got her into the backseat of his truck. She fell asleep within minutes and I slumped my head back against the chair. â€Å"How did you do that?† I asked quietly. â€Å"One of my friends was tripping out of their mind one night and I had to talk him out of jumping off the roof,† he explained. â€Å"It was all about making her realize that there was more than one scenario.† I nodded and we stayed quiet for the rest of the drive to my house. Ethan never brought it up to me, nor did he treat me differently and I was grateful for it. After a doctor’s visit, it was determined that my mother had started to suffer from ‘Delusions of Grandeur,’ which happens sometimes in bipolar patients. I finally pull away from the drawing when it’s nearly dark. I gather my sketchpad and pencils and head down the hill. In front of the arch iron entryway is Micha, sitting on the hood of his mom’s car, wearing jeans, and a black and red plaid shirt. His head is tipped down and wisps of his blonde hair cover his forehead as he messes around with his phone. I stop a little ways off from him. â€Å"What are you doing here?† His eyes lift from his phone. â€Å"I’m waiting for you.† â€Å"How did you know I was here?† â€Å"I saw you leave with your sketchpad and head this way, so I came up to check on you.† I take a tentative step forward. â€Å"How long have you been sitting here?† He slides off the hood and puts his phone away. â€Å"For a while, but I didn’t want to disturb you. You looked too peaceful.† I press my lips together and stare at him, craving to sketch him like I used to. He would sit on my bed and it was like he owned my hand. â€Å"Look, about the other night, I think – â€Å" He strides across the grass toward me, moving so impulsively that there’s no time to react as his finger covers my lips. â€Å"Just let it be for a while, okay?† Uncertain of his exact meaning, I nod anyway. He lets his finger fall from my lips, trailing a line down my chest, finally pulling away at the bottom of my stomach. â€Å"You want a ride home?† His voice comes out ragged. I glance at the grey sky and the birds flying across it. â€Å"That would be nice. Thank you.† Micha She’s preoccupied during the drive and so am I. I was so pissed off about my father that I got into the car about to do something reckless, however, then I saw Ella wandering down the street, and I followed her. The way she walked was very entertaining, her auburn hair blowing in the wind, and the way she swayed her ass in the short denim shorts she was wearing. It calmed me down watching her sit up on the hill and draw, but I can’t stop thinking about the phone conversation. â€Å"We should go somewhere,† I announce when we drive onto the main road. Ella jolts in her seat and turns away from the window. â€Å"I should probably go home.† â€Å"Come on.† I pout, hoping it’ll win her over. â€Å"Just come with me somewhere and we can relax.† She’s tempted. â€Å"Where exactly?† I turn the volume of the stereo down and let my arm rest on the top of the steering wheel. â€Å"To our spot by the lake.† â€Å"But it takes forever to get there.† Her eyes rise to the dark sky. â€Å"And it’s getting late.† â€Å"Since when have you been afraid of the dark?† â€Å"It’s not the dark I’m afraid of.† I sigh and downshift. â€Å"Come on, just you and me. We don’t even have to talk. We can just sit in silence.† â€Å"Fine,† she surrenders, tossing her sketchpad into the backseat. â€Å"Just as long as you don’t ask me questions.† I hold up my hand innocently. â€Å"Scouts honor. I’ll keep my questions to myself.† Her eyes narrow. â€Å"I know you’ve never been in the scouts before.† I laugh, feeling the pressure lift from my chest. â€Å"It doesn’t matter. I’ll keep my questions to myself, but with everything else, all bets are off.† She pretends to have an itch on her nose, but really it’s to obscure her smile and it makes me smile myself. *** Its pitch black by the time we reach our spot on the shore that’s secluded by tall trees. The moon reflects against the water and the night air is a little chilly. I get my jacket out of the trunk and offer it to Ella, knowing she’s cold because of the goosebumps on her arms and the way her nipples are poking through her shirt. She slips the jacket on and zips it up, covering up her perky nipples. I sigh, hop onto the hood, and open my arms for her to join me. Hesitantly, she climbs onto the hood, but stays at the front, with her feet propped up on the bumper, gazing out at the water. I scoot down by her and keep my knees up, resting my elbows on them. â€Å"What are you thinking about?† Her eyes are huge in the moonlight. â€Å"Death.† â€Å"What about death?† I wonder if we’re finally going to go back to that night. â€Å"That Grady’s going to die,† she whispers softly. â€Å"And there’s nothing I can do about it.† I brush her hair back from her forehead. â€Å"You need to stop worrying about everything that can’t be controlled.† She sighs and leans away from my hand. â€Å"That’s just it, though. It’s all I can think about anymore. It’s like this fixation I have no control over which makes no sense because I’m fixated on controlling the uncontrollable.† She’s breathing wildly. Shit. I need to calm her down. â€Å"Hey, come here.† I loop my arms around her waist and lie her down on the windshield with me. She rests her head on my chest and I play with her hair, breathing in her vanilla scent. â€Å"Do you remember when you decided that it would be a good idea if you climbed up the scaffolding in the gym?† â€Å"I wanted to prove to Gary Bennitt that I was as tough as the boys.† She buries her face into my shirt, ashamed. â€Å"Why do you remember everything?† â€Å"How could I forget that? You scared the hell out of me when you fell. Yet, somehow you managed to land on the board just below it.† â€Å"I thought I was going to die,† she murmurs. â€Å"I was so stupid.† â€Å"You weren’t stupid, you just saw life at a different angle,† I say. â€Å"I’ve always envied you for it. Like when you used to dance in a room where no one was dancing or how you stuck up for people. But there was always that wall you put up. You would never let anyone completely through.† She’s soundless for a while and I expect for her to push me away. But she sits up and hovers over me, her hair veiling our faces. Her breath is ragged, like she’s terrified out of her mind. â€Å"I opened up to you once,† she whispers. â€Å"When we were here in this spot doing this same thing.† I can’t take my eyes off her lips. â€Å"I’m not sure what you’re talking about.† She licks her lips. â€Å"I told you I didn’t want you dating Cassandra.† â€Å"Cassandra†¦ Oh, was that what that was about?† I start to laugh. â€Å"What’s so funny?† she asks, but I can’t stop laughing. She pinches my nipple and I jerk upward, smacking my forehead against hers. â€Å"Ow.† She blinks, rubbing her forehead and a laugh escapes her lips. â€Å"Tell me what’s so funny.† She looks beautiful, trying to be pissed, when deep down she’s relishing the moment. I’m enjoying myself, which I didn’t envisage tonight, but if anyone can cheer me up, it’s her. Like when my dad left and she caught me in the garage, clutching onto his tool box crying like a baby. She gave me her Popsicle and then just sat there with me until I ran out of tears. I eye her over and she fusses with her hair self-consciously. With one quick movement, I flip us over so my body is covering hers. â€Å"When I told Ethan about that day when you told me not to see Cassandra, he told me you had a thing for me. He’s usually not right about those things.† â€Å"I didn’t have a thing for you,† she argues. â€Å"I just didn’t want anyone else to have a thing for you.† â€Å"You’re adorable when you deny the truth. You always have been.† â€Å"Micha, I used to have studs on every item of clothing I owned and enough black eyeliner to make an entire sketch. That’s not adorable.† â€Å"It is on you.† I wink at her. She shakes her head and pokes a finger at my chest. â€Å"Don’t try and use your player moves on me.† We remain silent, frozen in the moment, until I finally speak again. â€Å"I have an idea.† Curiosity slowly takes over her face as I shift over her body. My arms are at the side of her head, barely holding my weight up. My face hovers above hers, our lips only an inch apart, and she lies perfectly still. â€Å"I want to kiss you.† She shakes her head promptly. â€Å"I don’t think that’s a good idea.† I trace one of my fingers over her lips. I’ve been going about this all wrong. I can’t force myself on her. I have to move slow and think of her as a skittish cat that needs to be approached cautiously. â€Å"Just kiss. I swear to God that’s all we’ll do.† I move my finger away from her lips. â€Å"And kissing’s not that scary, right?† â€Å"With you it is,† she says truthfully. â€Å"If you want me not to, just say it.† Taking my time, I leisurely lower my lips toward hers. She stays stationary, her big green eyes targeted on my mouth. Slowly, so she has time to let her thoughts slow down, I caress my lips across hers. A small gasp flees from her lips and I slip my tongue into her mouth. Her hands glide up my back and into my hair. My body conforms to hers as I explore her mouth with my tongue. She bites down on my bottom lip, sucking my lip ring into her mouth before releasing it. Fuck. She’s making this hard. I intensify the kiss as my body becomes more impatient, but I keep my promise and only kiss her, even when she fastens her legs around my waist and rubs up against me. Ella He said just kiss and it seemed okay, but now my body has developed a mind of its own. I’m writhing my hips against him enjoying the pleasure erupting inside me. He’s hard between my legs as he kisses me so fiercely that my lips are swollen. His fingers tangle in my hair and his tongue plunges deeper and deeper into my mouth the more I rock against him. My head falls back and my eyes open to the stars shining in the sky. It feels like I’m falling or flying†¦ I’m not sure, but whatever it is I can’t seem to control it. For a second, I want to capture the moment, put it in a jar, and always have it with me, but panic seizes my mind and I jerk away from his lips. His eyes snap open and his pupils are vast. â€Å"What’s wrong?† â€Å"Nothing†¦ It’s just†¦ I have to calm down.† I take a deep breath, my skin still tingling in the spots his hands touched. Micha nods, breathless. Carefully, he moves off of me and leans back against the window, securing his hand around mine. We don’t speak as we stare up at the sky. He traces his finger along the folds between my fingers and my eyelids drift shut. I feel a wall crumble, leaving behind dust, debris, and pieces that desperately need to be put back together. *** â€Å"Are you okay?† I ask Micha when we pull into my driveway. He’s been quiet the whole drive home and I can tell something’s bothering him. â€Å"Yeah, I’m fine,† he says with a shrug and then his gaze darts to the back window as headlights shine up behind us. â€Å"Although, you might not be.† My eyebrows furrow. â€Å"Why? What’s wrong?† He points a finger at a car parking at the curb in front of my house; a shiny black Mercedes with a familiar blonde-haired driver sitting in it. â€Å"Oh my God, is that Lila’s car?† I ask. â€Å"I’m guessing yes, since I doubt anyone around here owns a Mercedes.† Lila climbs out of the car and it’s clear that she’s been crying. Her eyes are swollen and her cheeks are red. She has her pajama bottoms on and a hoodie pulled over her head. The last time she walked around in an outfit like that she’d just broken up with her boyfriend. â€Å"I think she might have some issues at home,† I tell him, grabbing the door handle. â€Å"She acted like she didn’t want to go home.† â€Å"But you didn’t ask her about it?† he questions with an arch of his eyebrow. I bite my lip guiltily. â€Å"I wasn’t sure I wanted to know the answer.† God, I’m a terrible friend. Lila heads up the driveway and we get out to meet her around the back. Before I can say anything, she hugs me and starts to sob. I tense, not used to being hugged, except by Micha. â€Å"I didn’t want to go back there,† she cries. â€Å"I knew this was going to happen.† I look over Lila’s head at Micha for help. â€Å"It’ll be okay.† He gives me a sympathetic look and mouths, take her inside. I nod and he waves at me, getting back into his car. I guide Lila into the house holding her weight up for her like she’s ill. When I get her into my room, she curls up on my bed and hugs a pillow. I wait a minute before I speak. â€Å"Do you want to talk about it?† She shakes her head. â€Å"I just want to go to sleep.† â€Å"Alright.† I turn off the light and collapse onto the trundle. I need to get into my pajamas, but it’s been an exhausting day. â€Å"My dad hates me,† Lila whispers through sobs. I freeze and then sit up, squinting at her through the dark. â€Å"I’m sure he doesn’t hate you.† â€Å"Yes, he does,† she says. â€Å"He always says so – that he wished he had sons instead of daughters because they’re easier to deal with.† â€Å"Are you going to be okay?† I ask, unsure what else to say. â€Å"I will be. It’ll just take some time.† Was that the magical cure? Time. I flop back down and fall asleep to the murmur of her sobs. How to cite The Secret of Ella and Micha Chapter 10, Essay examples

Define the basic nutritional requirements of children and young people to ensure a balanced diet and meet government guidance free essay sample

Define the basic nutritional requirements of children and young people to ensure a balanced diet and meet government guidance The Government recommends that all healthy individuals should consume a diet that contains: †¢Plenty of starchy foods such as rice, bread, pasta and potatoes †¢Plenty of fruit and vegetables; at least 5 portions of a variety of fruit and vegetables a day †¢Moderate amounts of protein-rich foods such as meat, fish, eggs and alternatives such as nuts and pulses †¢Moderate amounts of milk and dairy foods †¢Less saturated fat, salt and sugar Children under the age of 5 who are not good eaters may need to take a supplement containing vitamins A, D and C. Children who have a good appetite and eat a wide variety of foods, including fruit and vegetables, might not need to take vitamin drops. Recommendations for protein, vitamins and minerals vary by age. Where different intakes for males and females are recommended, the higher value is identified in the table to ensure that the greatest need of the group is met: Nutrient1-3 Years4-6 Years7-10 Years11-14 Years15-18 Years Protein15g20g28g42g55g Iron7mg6mg9mg15mg15mg Zinc5mg6.5mg7mg9mg9.5mg Vitamin A400mcg400mcg500mcg600mcg700mcg Folate70mcg100mcg150mcg200mcg200mcg Vitamin C30mg30mg30mg35mg40mg Salt2g3g5g6g6g Carbohydrates- Carbohydrates are a good source of energy and the main source of a range of nutrients in our diet. They make up around one third of everything that we eat and they contain starch, fibre, iron and B vitamins. Types of Carbohydrates include: potatoes, rice and grains, bread, pasta, and cereal. Fruit and Vegetables- Fruit and vegetables are a vital source of vitamins and minerals. It is advised that we eat 5 portions of a variety of fruit and vegetables a day. There is evidence that people who eat at least 5 portions of fruit and vegetables a day are at lower risk of heart disease, stroke and some cancers. Dairy Food- Dairy foods are a good source of protein and calcium. Fats in milk provide calories for young children and essential vitamins such as vitamin B2 and B12. However, most of the fat in dairy foods is saturated fats. For older children and adults, eating too much saturated fat can contribute to becoming overweight. Protein- Protein is essential for growth and repair of the body. Protein is also a good source of a range of vitamins and mineral. Meat is a good source of protein, vitamins and minerals; it is also one of the main sources of vitamin B12. Fish is another source of protein, it is rich is Omega-3 fatty acids. Fats and Sugars- Fat and sugar are both sources of energy for the body, but if too much of this food group is consumed, the body is consuming more energy than it is burning, which leads to an increased body weight. This can lead to obesity, which increases the risk of type 2 diabetes, certain cancers, heart disease and stroke. Define the basic nutritional requirements of children and young people to ensure a balanced diet and meet government guidance free essay sample The Government recommends that all healthy individuals should consume a diet that contains: †¢Plenty of starchy foods such as rice, bread, pasta and potatoes †¢Plenty of fruit and vegetables; at least 5 portions of a variety of fruit and vegetables a day †¢Moderate amounts of protein-rich foods such as meat, fish, eggs and alternatives such as nuts and pulses †¢Moderate amounts of milk and dairy foods †¢Less saturated fat, salt and sugar Children under the age of 5 who are not good eaters may need to take a supplement containing vitamins A, D and C. Children who have a good appetite and eat a wide variety of foods, including fruit and vegetables, might not need to take vitamin drops. Recommendations for protein, vitamins and minerals vary by age. Where different intakes for males and females are recommended, the higher value is identified in the table to ensure that the greatest need of the group is met: Nutrient1-3 Years4-6 Years7-10 Years11-14 Years15-18 Years Protein15g20g28g42g55g Iron7mg6mg9mg15mg15mg Zinc5mg6.5mg7mg9mg9.5mg Vitamin A400mcg400mcg500mcg600mcg700mcg Folate70mcg100mcg150mcg200mcg200mcg Vitamin C30mg30mg30mg35mg40mg Salt2g3g5g6g6g Carbohydrates- Carbohydrates are a good source of energy and the main source of a range of nutrients in our diet. They make up around one third of everything that we eat and they contain starch, fibre, iron and B vitamins. Types of Carbohydrates include: potatoes, rice and grains, bread, pasta, and cereal. Fruit and Vegetables- Fruit and vegetables are a vital source of vitamins and minerals. It is advised that we eat 5 portions of a variety of fruit and vegetables a day. There is evidence that people who eat at least 5 portions of fruit and vegetables a day are at lower risk of heart disease, stroke and some cancers. Dairy Food- Dairy foods are a good source of protein and calcium. Fats in milk provide calories for young children and essential vitamins such as vitamin B2 and B12. However, most of the fat in dairy foods is saturated fats. For older children and adults, eating too much saturated fat can contribute to becoming overweight. Protein- Protein is essential for growth and repair of the body. Protein is also a good source of a range of vitamins and mineral. Meat is a good source of protein, vitamins and minerals; it is also one of the main sources of vitamin B12. Fish is another source of protein, it is rich is Omega-3 fatty acids. Fats and Sugars- Fat and sugar are both sources of energy for the body, but if too much of this food group is consumed, the body is consuming more energy than it is burning, which leads to an increased body weight. This can lead to obesity, which increases the risk of type 2 diabetes, certain cancers, heart disease and stroke.

Spirituality as a factor of well lived life

Introduction Human beings constantly assert that there is only one life to live. This thus compels them to make the most out of it as it is considered to be short. The cornerstone to a good life is happiness which according to the dictionary, is the expression of intense joy and contentment usually classified by most as an emotion, a notion which religious experts sharply differ with. They instead classify happiness as the sum of all factors considered as constituting a good life.Advertising We will write a custom research paper sample on Spirituality as a factor of well lived life specifically for you for only $16.05 $11/page Learn More Indicators of a good life In determining the factors that constitute a well lived life, different indicators are used which vary from individual to individual. While some may consider happiness as the leading indicator, others consider spirituality. In deciding whether a person leads a good life or not, Abraham Maslow, i n his 1943 paper, A Theory of Human Motivation (Harriman, 1946), suggested a hierarchical classification of needs. His research was solely based on the assessment of mentally healthy people who were achievers of their generation. These ‘specimens’ were chosen as they were role models and seemed to be the most content with their ways of life. The most basic needs were at the bottom of the pyramid which was of a physiological nature, fundamental to the survival of the human body. Others that followed were safety, love, esteem and self-actualization. The epitome of this classification was the desire of a person to be something more he already is. In this level of needs, lies the desire to be spiritual. Understanding spirituality Spirituality is defined as immaterial reality, a notion that allows a human being to understand the essence of his existence. The practices of prayer and meditation are the ways in which people connect to the spiritual world and grow their inner se lf. They are thus more contented with their own lives and the measure of this contentment is beyond that encompassed in mere happiness. It summary, spirituality is a level higher than normal happiness; in the broadest meaning of the word. People who are spiritual are at peace and co-exist harmoniously with fellow humans, nature, the entire universe and the divine realm. They unequivocally believe in immateriality and their needs transcend those Maslow described in his hierarchy. Spirituality has largely been associated with a religious experience; however, with the changing patterns and shift to secularism in the western culture (Burkhardt and Nagai-Jacobson, 2002), there has been a push to dissociate the two.Advertising Looking for research paper on philosophy? Let's see if we can help you! Get your first paper with 15% OFF Learn More This has led to the emergence of lay spirituality which captures all experiences which make up the human world but attempting to distan ce itself with the acquisitive views. This concept accepts all practices of meditation which they rank as very useful for human development but do not associate with prayers as there is no belief in God or any other supernatural being. This notion thus encompasses pluralism, personalized beliefs and openness to newer ideas that may not be tolerated by any particular religious doctrine. Spirituality, therefore, goes beyond religion as even atheists who are skeptic towards the existence of spirits also subscribe to it. The new definition of the term details the connection of a human to some force or energy which leads them to a deep self. Conclusion Spirituality, according to the above discussion is understood in many different ways depending on personal translation. The only point of convergence is that all those who have achieved spirituality are at the highest level of the human needs realization. They have achieved peace between themselves and their surroundings and that concludes that they are happy with the way they lead their lives. Contentment with life, as a consequence of spirituality, points to happiness and hence a good life. In conclusion, spirituality is the best indicator of a well lived life in comparison to the other indicators. References Burkhardt, M. A and Nagai-Jacobson, M. G. (2002). Spirituality: living our connectedness. New York. Delmar, Thomson Learning Inc. Harriman, P. L. (1946). Twentieth century psychology: recent developments in psychology. The philosophical library, Inc. This research paper on Spirituality as a factor of well lived life was written and submitted by user Zoie C. to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.

Practice Experience, Decision-Making and Professional Authority The WritePass Journal

Practice Experience, Decision-Making and Professional Authority Abstract Practice Experience, Decision-Making and Professional Authority .   I focus upon an incident where I worked alone with a service user suffering domestic violence.   There is no legal definition of domestic violence (DV). However, the government describes DV as â€Å"any incident of threatening behaviour, violence or abuse (psychological, physical, sexual, financial or emotional) between adults who are or have been in a relationship together or between family members, regardless of gender and sexuality† (Home Office 2012 [online]). Most reported DV cases are directed by men towards women. DV also occurs in same sex relationships and in a relatively small number of cases, by women against men. The case study is described, and my experiences of decision-making and how I exercised professional authority brought out.  Ã‚   I explore the theories surrounding the areas I look at in the case study, particularly the ways theory links with practice. I also look at the legal policy framework which is relevant to the case study. I also bring out personal skills including communication and look at the role they played. 2. Case Study I started my placement with a domestic violence agency in an inner city London borough in March, 2012.   The agency works exclusively with service users fleeing domestic violence.   Ã‚  The incident I have chosen for this case study involved lone working with a service user who had approached the organisation that I am on placement with for support regarding domestic violence abuse she was suffering at home. The service user will be referred to as SS in accordance with the Data Protection Act 1989.  Ã‚   SS is a French national who had relocated to the United Kingdom with her mother at the age of 14. Her relationship with her mother had broken down because she remained in a relationship with the perpetrator (Perp) at her mother’s disapproval. She had been married to the Perp for three years. They have two children, age 14 months and 2 months, her first child is a girl and the new born baby a boy. The perp started to be controlling after she had their first child. After t heir second child was born the abuse started happening more frequently. On a particular occasion, the perp grabbed SS, threw her against the wall and hit her several times across the face. She approached my placement agency for support after she was advised by another agency. SS attended as a duty. Therefore, the onus was on me as the duty staff to assess her circumstances and offer appropriate advice and support to safeguard SS and her children. As such, I had a role of responsibility, with the future wellbeing of SS partly   in my hands.     I prepared for the DV2 assessment in line with the agency’s lone working policy. I signed SS in and informed my peers of the room where the assessment was taking place; I also booked her in the duty book. I made sure the assessment room I choose was available, clean, spacious and comfortable as there was a professional from another agency and her children with her also. I also made sure that SS had a private space to discuss her issues and express her feelings without interruptions from her children. I had provided toys to distract her eldest child whilst the assessment was going on.   SS informed me during the assessment that some of the documents that she might need to present at the Homeless option s Centre (HOC) were at home, she offered to quickly rush home to pick them up whilst the perpetrator (Perp) was still at work. I advised her that the risk associated with such action might be too great for the children and herself, as the perp might walk in on them. I gave her options to either get a police escort or ask a friend who lives near the house to get such documents for her. By so doing I was able to manage the risk to SS and her children. I used the DV2 assessment form to understand her needs, whilst also working together with SS to respond to her crisis situation. I was able to address behaviours that posed a risk to her and the children, I recognised and acknowledged the risk to SS if she returns to the house alone. She agreed that going back to the family house will put the children and her at risk. The risk was assessed and plans were put in place to manage such risk and minimise the risk of further abuse to her and the children in accordance to the GSCC code of practice and Every Child Matters agenda, 2004. Through the DV2 assessment, I also able to identify the need for safe and comfortable accommodation to manage such identified risk to SS and her children. However, my concern was that she might go back to the abusive relationship if appropriate support was not available.   SS would still need to pass the habitual residency test (HBT) as an in EEA national to ascertain her rights to public funds in the United Kingdom because of SS’s nationality (French). If she fails this test (HRT), she might not be eligible for benefits, and the stress of managing with two children without an income might be too much for her to cope with alone. Hence, without adequate support available, she might return to the abusive environment from where she is trying to flee.   I wrote a housing letter to the HOC to support her claim for domestic violence and also offered to attend the HOC centre with her to advocate on her behalf. By so doing I was able to mitigate the risk to which SS and the children were exposed. I gave her a voice and also considered the children’s situation and the statutory support that might be available for them. I searc hed for local refuges to address her housing need, made a referral to children’s social services, provided food vouchers and made arrangements for them to be accommodated away from the perp’s area of influence. 3. Theoretical Context / Legal Policy and Framework, Application to Case Study This case can be seen in the context of a number of theories relevant to the situation, and also in the context of current legal policy and legal framework. This section will look at these connections, first at the theoretical context and next at the legal situation. 3.1 Theoretical Context and Case Study Application The psychologist Maslow suggested that all human beings have a number of needs which need to be satisfied in order for a person to live at his or her full potential. These needs, he also suggested, form a hierarchy, that is, they are ordered. ‘Lower’ needs are required to be satisfied first, before other needs come into play   (Maslow 1943).   Physiological needs are the most basic, including things we need to do to survive (eating, sleeping etc.).   Next come security needs, that is the need for shelter and access to health services. Once these are satisfied, social needs become relevant. These are the needs for feeling part of a group, affection and similar. These are frequently satisfied by work, friends and family.  Ã‚   Higher level needs are the need for esteem, that is, for feeling good about oneself and social recognition, and the need for ‘self-actualisation’,   the need for personal growth and fulfilling one’s ability to the full ( Zastrow et al 2009). In terms of this model, SS was clearly struggling with needs at the lowest level, physiological and security needs. She was finding it difficult to access funds for her children to eat, and given that the perp. lived in the family home, her housing needs were threatened. SS’s health would also be under threat should she return to the family home. As such, the model predicts that SS would be feeling exceptionally insecure and vulnerable: partially met or unmet human needs are associated with increasing vulnerability (De Chesnay and Anderson 2008, p. 489). Another theoretical model is provided by crisis intervention theory’. This is a particularly useful model as it is directed towards practical action (Coady and Lehman 2007).  Ã‚  Ã‚  Ã‚   It is based around the idea that a crisis presents both a challenge (in an extreme form) and an opportunity (Roberts 1995). In other words, a crisis can lead to positive change. One leading developer of the idea was Erkison (1950) CITE) who looked at the role   played by crisis in the maturation of typical human beings. Eric Lindemann (1944) developed a systematic model to deal with crisis. A model suggested by Golan (1978) is useful for this case study. He suggested four stages: first, the person suffering the crisis develops a subjective response to the situation. Next, this leads to upset or lack of balance, previous ways of dealing with problems dont apply. At this stage, though it is chaotic, there is some hope for new approaches.   Thirdly, this particular crisis can link to unres olved conflicts in the person. Finally, the first three stages lead to new opportunities to develop new ways of dealing with potentially damaging situations. It is the role of the professional to help the service user see these new ways of responding   (Roberts 1995). In terms of the case study, SS seems to be at a crisis point, and one which led to the development of new ways of dealing with her abusive partner.  Ã‚   One incident led to SS presenting to the agency, but this crisis incident was the catalyst for realising that her previous attempts to deal with the situation of violence, through staying with her abusive partner, were not working. Though greatly distressed, particularly by the upheaval she and her children were experiencing, SS learnt new ways of dealing with the situation, primarily removing herself from the family home and asking authorities for support in finding a new home. I personally found psychodynamic theory, which aims to uncover the reasons for domestic abuse in early childhood situations, less useful to this particular case study. The ideas about how rage from childhood is visited upon an adult’s current partner (Sanderson 2008) are, I felt, useful as a background, however psychodynamic theory seems to advocate long-term therapeutic treatments which just aren’t possible or appropriate given the immediate emergency of the situation. However, I did find that ideas like this helped me step back and understand that sometimes people’s actions stem from very deeply rooted issues which are hard to tackle. This has helped me overcome an early frustration with some client’s inability, seemingly, to see what is going on clearly. I felt the more practically focussed therapeutic techniques were more useful. These included person-centred and task-centred approaches.  Ã‚   Person-, or client-, centred therapy was developed by Rodgers in the 1940’s. It suggests that the client is at the centre of any counselling process, and that it is the task of the counsellor (or, in this case, the social services professional) to understand how the client sees the world. Without this understanding, it is not possible to help the client move forward.   The person-centred approach advocates avoiding lecturing, manipulating, bribing, directing or otherwise trying to change the client’s behaviours from outside. Rather, the need is to empower the client to grow (Vincent 2005).   There are a number of techniques which can be used, including empathy, congruence (letting the client see you as you are), and positive regard (Jarvis et al 2002).  Ã‚   I found this theory particularly useful, as it made me realise t he need to abandon judgement of SS, and get to know how she saw the situation. The idea of congruence helped me see that I need not present an entirely blank, professional face, but could inject something of my own personality into our meetings. The task-centred approach is time-limited, that is (unlike many psychodynamic therapies) it is carried out over a time period fixed in advance. It is therefore useful in situations like this one where only a limited period of time is available. The idea was developed in the USA, but has become widespread elsewhere. It involves client and professional agreeing together some goals to be reached over a clearly defined period of time. It emerged from a background where social work was hampered by a psycho-analytic perspective on client behaviour, and thus offered a much-needed way to focus upon specifics and deliverables. The approach involves mutual agreement about goals, problems which the service user can see for themselves and which they can work on by themselves between sessions. The focus is upon what the user wants to change (Wilson et al 2008). I found this approach a useful one to combine with a person-centred perspective. I was able to agree with SS things she wanted to change (living with her abusive partner) and we agreed tasks to complete to achieve this overall goal, including contacting other agencies for housing advice. Ideas about risk management and risk assessment were also very useful in this particular case, as there was a risk of harm from the perp. for the client, and perhaps also for social service professionals who became involved. Because perceptions of risk are highly subjective, there is a need to objectify the existing risk(s) as far as possible to try and eliminate as much bias as one can. Normative models of risk address how to make the best decision when there are a number of possible options or ways forward are useful: they allow the assessment of how likely certain outcome are   (Messer and Jones 1999, p. 90). As this situation involves young children, structured risk assessment models are useful, as they allow the situation to be assessed in terms of childrens needs as well as the mothers (Harne 2011). Many now advocate shifting away from risk assessment looking at single factors to looking at the interaction of factors across individual, social and cultural domains (Chalk and K ing 1998, p. 277) 3.2 Legal and Policy Framework, and Case Study Application There are a number of legal and policy documents which are also relevant to the case study.   The Domestic Violence, Crime and Victims Act 2004 was designed to extend the protection available to vulnerable adults and children, and included a new offence of ‘causing or allowing the death of a child or vulnerable adult’, designed to address cases where two partners failed to admit responsibility for child injury. It also made common assault an arrestable offence, added new powers to fine offenders, and changed non-molestation orders to allow non-compliance to attract prison sentences of up to 5 years.   The circumstances under which a case can be heard without a jury are also extended (Guardian 2009). This Act offers a range of additional protections for the victims of domestic violence, in terms of criminal proceedings which might be brought against the perpetrator. For the case study above, SS has not reached the point of deciding to press charges against her partner . My first concern is to make sure she has secure accommodation and is safe from further abuse. However, in time, she will consider the possibility of legal action against her partner, and I feel the Act allows extra protection for her which might make her more likely to consider it. As the situation is a complex one, a number of other legal frameworks and policies are relevant.   Because SS is unable to return to the family home because of risk of further abuse, the Housing Act 1996 is also relevant. Under the act SS is likely to be eligible to be housed by her local authority, as it places a duty on authorities to advise and possibly house people if they are under threat of becoming homeless, have a priority need, are not intentionally homeless and have a local connection to the area (amongst other criteria) (Housing Act 1996). These things apply in SS’s case. Additionally, the code of guidance for local authorities in regards to homelessness was published in 2008. This spells out the duty of local authorities more clearly, and also suggests a need for social services and housing bodies to work together more closely (Department for Education and Skills 2008). However, because SS is originally from France, there is a question regarding her access to public funds. In order to benefit from the help she needs, she needs to pass the Habitual Residence Test. The Habitual Residence test was developed as a way to ensure that only those people with a connection to the UK can claim benefit here.   The concept is not legally defined, and in practice a number of markers are involved in decision making, including length of stay, continuity of stay, the persons intentions and the nature of their residence (Currie 2008). It is claimed that the concept of habitual residence is more stringent than the concept of ordinary residence found elsewhere in law. It is likely that the presence of the children, SS’s history and her desire to remain in the country will all count in her favour, however it represents another obstacle to the security of her future (Harris 2000).  Ã‚   Additionally, the 2002 Nationality, Asylum and Immigration Act restricts e ntry and leave to stay in the UK. Finally, I was also influenced by the Data Protection Act 1989, which protects the confidentiality of client data, for example dictating that I refer to clients only by initials or pseudonyms, and by the GSCC Code of Practice. The latter is particularly important, as it provides the framework within which social workers should operate in the UK.   Part of the guidelines are concerned with the need to protect and promote the interests of the client, establish their trust and confidence, and promote their independence. These aspects are particularly interesting in the light of the theory discussed above, as they are broadly in line with the aims of client-centred and task-centred approaches. 5. Conclusion This essay has addressed a case study taken from my experience working with victims of domestic violence.   I have tried to show how theory is relevant to the situation I describe, and how legal issues are also relevant.   It was necessary for me to make a number of decisions throughout the experience I describe, however perhaps the most important skill I brought to play was that of communication. I had to communicate not only with other agency staff about this case, but also with multiple outside agencies (housing, benefits and similar) and, perhaps most importantly, with the client. The section on theory above has pointed out some of the therapeutic perspectives which were useful, and the client-centred approach, with its emphasis upon empathy and understanding, have been particularly helpful to me in the communication process. I have also used feedback from other staff members and reflective feedback processes to understand the impact of how I communicate to clients, and use t his feedback and reflection to make improvements to my skill set.   SS’s case history, like all cases of domestic violence I have come across, is complex and requires an equally complex set of skills on the part of the social worker to produce the best possible outcomes. 6. References Chalk, R A and King, P (1998) Violence in Families: Assessing Prevention and Treatment Programs, National Academies Press, USA Coady, N and Lehman, P (2007) Theoretical Perspectives for Direct Social Work Practice: A Generalist-Eclectic Approach (2nd edn), Springer Publishing Company, USA Currie, S (2008) Migration, Work and Citizenship in the Enlarged European Union, Ashgate Publishing, Ltd., UK De Chesnay, M and Anderson, B A (2008) Caring For The Vulnerable: Perspectives in Nursing Theory (2nd edn), Jones Bartlett Learning, Sudbury, MA Department for Education and Skills (2008) ‘Homelessness Code of Guidance’, HMSO, London Erikson, E (1950) Childhood and Society, WW Norton, NY. Golan, N (1978) Treatment in Crisis Situations, Free Press, New York The Guardian (2009a) ‘Domestic Violence Act’, [online] (cited 27th May 2012) available from guardian.co.uk/commentisfree/libertycentral/2009/jan/13/domestic-violence-act The Guardian (2009b) ‘Immigration, Asylum and Nationality Act 2006’, [online] (cited 26th May 2012) available from guardian.co.uk/commentisfree/libertycentral/2009/jan/15/immigration-asylum-nationality-act Harne, L (2011) Violent Fathering and the Risks to Children: The Need for Change, The Policy Press, Bristol Harris, N S (2000) Social Security Law in Context, Oxford University Press, Oxon. The Home Office (2012) ‘Domestic Violence’ [online] (cited 28th May 2012) available from homeoffice.gov.uk/crime/violence-against-women-girls/domestic-violence/ Jarvis, M, Putwain, D and Dwyer, J (2002) Angles on Atypical Psychology, Nelson Thornes, Cheltenham, Glos Lindemann, E (1944) ‘Symptomatology and management of acute grief’,   American Journal of Psychiatry, 101, 141 -148. Maslow, A (1943) ‘A theory of human motivation’, Psychological Review, 50, 370-96. Messer, D J and Jones, F (1999) Psychology and Social Care, Jessica Kingsley Publishers, UK Sanderson, C (2008)   Counselling Survivors of Domestic AbuseAuthorChristiane Sanderson, Jessica Kingsley Publishers, UK Vincent, S (2005) Being Empathic: A Companion For Counsellors And Therapists, Radcliffe Publishing, UK Wilson, K, Ruch, G and Lymbery, M (2008) Social Work: An Introduction to Contemporary Practice, Pearson Education, Harlow, Essex Zastrow, C and Kirst-Ashman, K K (2009)   Understanding Human Behavior and the Social Environment (8th edn), Cengage Learning, Belmont, CA

Analyze the handover between two WLAN, two Wimax and two UMTS networks

Analyze the handover between two WLAN, two Wimax and two UMTS networks ABSTRACT In recent years, telecommunication has flourished extensively so much that several areas of studies coexist now thanks to multiple technologies. One of them is heterogeneous handover which is a concept that aims to provide continuity of connection while crossing different networks. In this thesis, our main objective is to analyze the handover between two WLAN, two Wimax and two UMTS networks. The vertical handover decision is taken on the basis of various algorithms such as variance-based algorithm, taguchi algorithm, which calculates the variance of parameters such as delay, jitter, bandwidth and packet loss for the above networks, and selection of the network having most parameters with minimum score. These algorithms are calculated and the decision factors for each wireless network are compared, in order to detect and trigger a vertical handover. The factors can be classified as beneficial, i.e., the larger, the better, or on the basis of cost, i.e., the lower, the better. This algorithm is also compared with other algorithms such as MEW (Multiplicative experiment weighting), SAW (Simple Additive Weighting), TOPOSIS (Technique for order preference by similarity to ideal solution) and GRA (Grey Relational Analysis). These algorithms are appropriate for different traffic classes. Simulation results for the proposed algorithm in Matlab is discussed and compared with other multiple attribute decision making algorithms on the basis of bandwidth, jitter, delay etc. It can be seen that the proposed algorithm causes the minimum packet delay than others. Jitter is also comparatively less than other algorithms. Besides, it provides the highest bandwidth than any other MADM algorithm. Keywords:-UMTS, SAW, MEW, GRA, TOPSIS, WLAN and Wimax Chapter-1 Introduction 1.1 History of mobile services ‘ The journey of mobile telephony began with the 1st generation services. The design for it was developed by AMPS (Advanced mobile phone system) in 1970 and it is based on analog cellular technology. The data bandwidth provided by the system was just 1.9 kbps and it used TDMA multiplexing. Then, the 2nd generation of mobile services was introduced in 1981.The 2G systems are still largely used for voice calls. The data bandwidth provided was 14.4 kbps [1] and the technology used was TDMA and CDMA. It is based on digital technology and also provided short messaging services or SMS along with voice communication. Similarly, it provided circuit switched data communication services at low speed. In 1999, the technology switched to 2.5 G, which used GPRS, EDGE as the standards. It provided higher throughput for data service up to 384 kbps. Later, in 2002, the 3G services were introduced, providing high quality audio, video and data services. Which also provided broadband data capabilities up to 2 Mbps. It mainly uses packet switched technology which utilizes the bandwidth more efficiently. In 2010, when 4th generation of cellular technology was introduced, it was expected to complement and replace the 3G networks. The key features of 4G mobile networks is that it can deliver information anywhere and anytime using seamless connection.4G network is an IP based network which gives access through collection of various radio interfaces. Its network provides access to best possible service with seamless handoff, combining multiple radio interfaces into a single network for subscriber to use. Thus, users have different services with an increased coverage. It does not matter whether there is failure or loss of one or more networks, the 4G technology keeps all the networks integrated into IP based system, which require vertical handoff for seamless connection between the networks. As the number of users are responsible for enhancing the qu ality of 4G service, the very process becomes an indispensable component. While the 4G technology has its genesis in the idea of invasive computing, software defined radio is the prominent adhesive behind the entire process. Here the software defined radio is programmable and able to transmit and receive a wide range of frequencies while emulating any transmission format. It should offer high speed of 100 Mbits for stationary mobile and 20 Mbits while travelling having network capacity 10 times faster than 3G networks. This increases the download speed to 1 second for 1Mbyte of file compared to 200 seconds in 3G networks. Which should support fast speed volume data transmission at lower cost. The obviously it should provide seamless connection between multiple wireless networks and mobile networks. For this, the support of vertical handoff is essential. Apart from it, it is expected that seamless multimedia services are provided it being an IP-based system, which also replaces SS7 (signaling system 7) that consumes considerable amount of bandwidth. Due to IP-based network, optimum usage of bandwidth is expected. 1.2 Motivation ‘ There are several communication systems such as the Ethernet, Wireless LAN, GPRS and 3G coexisting with their own different characteristics such as bandwidth, delay and cost. Wireless mobile users require high quality of service (QoS) and one of the factors directly affecting QoS is the number of call drops. Therefore, it has to be reduced or eliminated, possibly, to achieve high QoS. The number of call drops experienced by a system mainly depends on its channel assignment and handoff schemes. Since majority of WLANs are deployed in the areas like hotels, cafes, airports, offices, etc, the speed of the users are generally normalized within the WLAN coverage area. In WLAN/Cellular network interworking, a user can either have access from micro layer or from macro layer of cellular network depending whether he wants slow or fast speed. Basically, in cellular networks, user speed is the primary factor to determine whether a user is fast or slow and that information is subsequently used to handle vertical handoff. Since the speed information about the users are not directly available when they are in WLAN coverage area ,the vertical handoff schemes employed in cellular networks are not directly suitable for solving vertical handoff problem in Cellular/WLAN interworking. This raises to many important questions. Assume that the speed of each user in a WLAN coverage area is within small threshold value. Normally, when a user is outside WLAN coverage area, the type of user whether fast or slow, is determined on the basis of the user speed. Now the question is how to determine the type of user, whether fast or slow, when it is within the WLAN coverage area? A fast user can become slow temporarily due to various conditions such as traffic signals, turns, etc. Is the speed alone sufficient to determine whether a user is slow or fast? If not then (i) What other parameters can be used to determine whether a user is fast or slow and, ii) How can they be obtained? In fact, this lack of clarity inspired the researcher to develop a vertical Handoff decision algorithm to solve vertical handoff problems. 1.3 Scope of thesis ‘ With greater mobility and easy acces, telecommunication consumers have become demanding, seeking services anywhere and anytime. Thus, the integration of WLAN (Wireless LAN), Wimax and cellular networks such as WCDMA (wideband CDMA) system should be error free for seamless efficient communication which is the 4th generation technology. The seamless and efficient handover between different access technologies known as vertical handover is essential and remains a challenging problem. The 4G is seen as convergence and integration of various wireless access technologies. The existing cellular systems such as GSM and CDMA2000 support low bandwidth over a large coverage area. However, the wireless networks such as WLAN supports high bandwidth over a short coverage area. Moreover one of the major design issues of 4G is the support of vertical handover. Interestingly this is different from a ‘horizontal handoff’ between different wireless access points that use the same technology. Switching between two dissimilar networks for mobile terminal (e.g. between UMTS WLAN) is termed as Vertical Handover A vertical handover involves two different network interfaces for different wireless technologies. It can happen in two ways. Firmly when the mobile user moves into the network that has higher bandwidth and limited coverage, a vertical handover request is generated since the mobile user may want to change its connection to the higher bandwidth network to enjoy the higher bandwidth service. This type of vertical handover is called downward vertical handoff. Secondly when the mobile user moves out of its serving higher bandwidth network, it has to request a vertical handover to change its connection to the network with low bandwidth and wide coverage. This type of vertical handover is called upward vertical handover. Chapter-2 Research objectives 2.1 Objectives The present research aims at making comparison between various existing multiple attribute decision making algorithms for realization of vertical handoff such as MEW (Multiplicative Exponent Weighting), SAW (Simple Additive weighting), TOPSIS (Technique for order preference by similarity to ideal solutions) and GRA (Grey relational Analysis) which are MADM (Multiple attribute decision making) ranking algorithms and the proposed vertical decision algorithm. For this comparison, various heterogeneous networks such as UMTS (Universal Mobile Telecommunication services), WLAN (Wireless Local area networks), WiMAX (Worldwide interoperability for microwave access) need to be taken into consideration. Comparison will be mostly on the basis of various parameters such as bandwidth, jitter, packet delay, packet loss, etc. In addition, the comparison may be for different types of traffics such as data connections and voice connections. As all the above mentioned algorithms are multiple attribute algorithm, due importance is given to parameters to be considered in the algorithms. The performance evaluation of the proposed decision algorithm should be done on the basis of parameters mentioned above. For various types of traffics, how the algorithm performs can be seen. Depending on the performance, we can conclude Which algorithm is suitable for which traffics. In voice connections, 70 % importance is given to the packet delay and jitter i.e. by assigning weights to these parameters and equal distribution of weights to the other parameters or attributes. If any of the algorithms performs well then that particular algorithm can be considered to be best suited for voice connections. In da ta connections, 70% importance is given to the parameters such as bandwidth i.e. by assigning the weight to the bandwidth and remaining weight is equally distributed among the parameters. If any of the algorithm performs well in this case, then the particular algorithm is suitable for the data connections. The ultimate aim being development of a decision making algorithm which works well for both voice connections and data connections. ‘ 2.2 Methodology In order to realize vertical handoff using the existing multiple attribute decision making algorithm and evaluate the performance of each of the algorithms along with the proposed algorithm, we are considering the selection of network in 4G environment. Here, three types of networks such as UMTS (Universal Mobile Telecommunication services), WLAN (Wireless Local area networks), WiMAX (Worldwide interoperability for microwave access) are combined and there will be two networks of each type. In this thesis, four decision criteria are evaluated and compared to realize vertical handoff considering the available bandwidth (Mbps), packet delay (ms), packet jitter and packet loss (per 106 packets). The range of value for various parameters are as follows: Available bandwidth for UMTS network 0.1-2Mbps, Packet delay for UMTS network 25-50ms, Jitter for UMTS network 5-10ms. Bandwidth for WLAN network 1-54Mbps, Packet delay for WLAN network 100-150ms, Jitter for WLAN network 10-20ms. Bandwidth for Wimax network is 1-60Mbps, while for packet delay for Wimax network is 60-100ms, and Jitter for Wimax network is 3-10ms.The values for the weights to be assigned for different services are considered as Case1: packet delay and jitter are given 70 % importance and the rest is equally distributed among other parameters, this case is suited for voice connections and whereas Case 2: available bandwidth is given as 70% importance, this case is suited for data connections. For each algorithm, 10 vertical decisions were considered of each case separately. Performance evaluation is done for two cases namely voice connections and data connections. These cases are evaluated using MATLAB v7.6 release 2009 software tool. Next, by using artificial neural network, we can design a system to take vertical handoff decision. Here, input parameters such as samples of received signal strength and bandwidth is applied to input layer, hidden layer does some processing depending upon the number of neurons and the algorithm chosen. The output layer gives the ID of selected candidate network. In, ANN-based method, there is handoff between WLAN and Cellular networks. Here, two parameters are taken into consideration i.e. RSS a Bandwidth as an input for neural network. The RSS samples for training neural network for both WLAN cellular networks are -60dBm,-70 dBm,-80 dBm,-90 dBm. Similarly, bandwidth samples for WLAN are 54, 30,10,1 Mbps. Bandwidth samples for cellular network are 14.4, 9.6, 4.5,2 kbps. By using combination of RSS bandwidth parameters, we could make 256 samples of input for ANN. These samples of output samples for vertical handoff decision are also fed to ANN. Using Levenberg-Marquardt method for ANN, 180 samples are used for training, 38 samples for validation and 38 samples for testing. Based on ANN developed system, it could take vertical handoff decision from cellular to WLAN. Lastly, ns-2 software tool can also be used. NS-2 simulation is done using nodes of 802.11 and nodes of 802.16 Wimax. Four nodes of 802.11 nodes (Access points) are used and four nodes of 802.16 nodes (Base station) NIST module of 802.16e are used in ns-2. In this case, out of the existing algorithm best algorithm with best score is selected for triggering vertical handoff decision. Here, in this case, various parameters such as Bandwidth, Bit error rate, trust level etc were considered for vertical handoff decision. This can be tested against various available traffics in ns2 such as CBR (Constant bit rate) which corresponds to real time traffic (for voice communication) and FTP (file transfer Protocol) which corresponds to non real time traffic. The performance evaluation for various traffics can be done on various parameters such as Packet delivery ratio, throughput, jitter and packet dropping ratio etc with simulation time. 2.3 Related Work Enrique Stevens Navarro and Vincent W.S.Wong [2], in their paper, have compared four different vertical handoff decision algorithm namely, MEW (Multiplicative Exponent Weighting), SAW (Simple Additive Weighting), TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), and GRA (Grey Relational Analysis). All four algorithms allow different parameters (e.g., bandwidth, delay, packet loss rate, cost) to be considered for vertical handoff decision [2]. Both Authors found that MEW, SAW, and TOPSIS provide almost the same performance to all four traffic classes. Only GRA gives a slightly higher bandwidth and lower delay for interactive and background traffic classes. Jose.D.Martinez, Ulises Pinedo-Rico and Enrique Stevens Navarro, in their paper, have given a comparative analysis of the multiple attribute decision algorithms [3]. In this paper, the authors provided a simulation study of several vertical handoff decision algorithms in order to understand its performance for different user applications. They considered two different applications: voice and data connections. Algorithms such as SAW (Simple Additive Weighting) and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) are suitable for voice connections. These algorithms provided the lower values of jitter and delay packet available in a 4G wireless network. In a data connection case, GRA (Grey Relational Analysis) and MEW (Multiplicative Exponent Weighting) algorithms provided the solution with highest available bandwidth necessary for this application. Chapter-3 Classification of vertical handoff algorithms 3.1 Need for vertical handoff Currently, the trend in mobile communications is not one network technology replacing another, but the interoperability between different overlapping networks. Therefore it is obvious that many wireless networks will coexist and can complement each other in an all-IP based heterogeneous wireless network. This can facilitate mobile users’ access to internet easily and connectivity of IP anywhere, anytime using the ‘best’ possible network. This is mainly due to the fact that different wireless networking technologies have their own advantages and drawbacks. Access to various wireless systems results in heterogeneous networks that can offer overlapping coverage of multiple networks with different technologies. For example, low cost and high speed Wi-Fi (WLAN) network will be accessible within limited range of ‘hot-spot’ areas and will be complimented with cellular network offering wide area coverage such as UMTS or Wimax. As a consequence, some fundament al problems must be solved for the users to navigate a 4G wireless network seamlessly. For this, mobile terminal equipped with multiple interfaces to handle different technologies is required. Furthermore, applications running on mobile terminal with multi-mode terminals in a 4G environment can switch between different networks supporting different technologies without degrading the quality of the link. But the Internet routing model forces mobile terminal to find new IP address for an interface while roaming in another network in 4G environment. It is assumed that applications can easily manage mobility and can handoff to the best possible network; of course some method is required to adjust media streams to the bandwidth available. 3.1 Types of vertical handoff There are various ways to classify vertical handoff algorithms. In this thesis, we have classified the vertical handoff algorithms into four groups based on the handoff criteria as given below: RSS-based algorithms: RSS is used as the main handoff decision criteria in this group. Different strategies have been developed to compare the RSS of the present point of attachment. In this RSS-based horizontal handoff decision, strategies are classified into the following six subcategories namely: relative received signal strength, relative received signal strength with threshold, relative received signal strength with hysteresis and threshold, and prediction techniques. For vertical handoff decision, relative received signal strength cannot be applicable since the signal strength from different types of networks cannot be compared directly due to the different technologies involved. For example, different thresholds for different networks. Furthermore, other network parameters such as bandwidth are combined with RSS in the vertical handoff decision process. Bandwidth-based algorithms: Available bandwidth for a mobile terminal is the main criterion in this group. In some algorithms, both bandwidth and signal strength information are used in the decision process. Depending on whether RSS or bandwidth is the main criteria an algorithm is categorized either as signal strength based or bandwidth based. Cost function based algorithms: This class of algorithms combine metrics such as monetary cost, security, bandwidth and power consumption in a cost function based algorithm, and the handoff decision is made by comparing the score of this function for the candidate networks. Different weights are allotted to the different input parameters depending on the network conditions and user preferences. ANN and fuzzy logic based algorithms: These vertical handoff decision algorithms attempt to use richer set of inputs than others for making handoff decisions. When a large number of inputs are used, it is very difficult or impossible to develop, formulate handoff decision processes. Analytically hence, it is better to apply machine learning techniques to formulate the processes. The survey reveals that for the fuzzy logic and artificial neural networks based techniques can be used. The Fuzzy logic systems allow expertise of humans for qualitative thinking to be incorporated as algorithms to enhance the efficiency. If there exists comprehensive set of input-desired output pattern, artificial neural networks can be trained to create handoff decision algorithms. By using consistent and real-time learning techniques, the systems can monitor their performance and change their own structure to create very effective handoff decision algorithms. 3.3.1 RSS based vertical handoff In this, the handoff decisions are made by comparing RSS (received signal strength) of the current network with the preset threshold values. These algorithms are less complex and may be combined with other parameters such as bandwidth, cost etc to have a better handover decisions. We describe here three RSS based algorithms in the following sections. A) ALIVE-HO (adaptive lifetime based vertical handoff ) algorithm – Zahran, Chen and Sreenan proposed algorithm for handover between 3G networks and WLAN by combining the RSS with an estimated lifetime (duration over which the current access technology remains beneficial to the active applications). ALIVE-HO always uses an uncongested network whenever available. It continues using the preferred network (i.e. WLAN) as long as it satisfies the QoS requirements of the application [5]. Two different vertical handoff scenarios let us discuss: Moving out of the preferred network (MO) and Moving in to the preferred network (MI), where the preferred network is usually the underlay network that provides better and economical service. Hence, extending the utilization of WLAN as long as it provides satisfactory performance is the main consideration of vertical handoff algorithm design. We observe the method through the following scenarios. In the first scenario, when the MT moves away from the coverage area of a WLAN into a 3G cell, a handover to the 3G network is initiated. The handover is done under following conditions: (a) RSS average of the WLAN falls below predefined threshold. (MO threshold) and (b) the estimated lifetime is at least equal to the required handoff signaling delay. The MT continuously calculates the RSS mean using the moving average method.[4] [K] = Here [k] is RSS mean at time instant k, and Wav is the window size, a variable that changes with velocity of the velocity of mobile terminal. Then, the lifetime metric EL [k] is calculated by using [k], ASST Application signal strength threshold),S[k],RSS change rate. EL[k] = [k] ‘ ASST S[k] ASST (Application signal strength threshold) chosen to satisfy the requirements of the active applications. S[K] represents RSS decay rate. In second scenario, when the MT moves towards a WLAN cell, the handover to the WLAN is done if the average RSS is larger than MI Threshold. WLAN and the available bandwidth of the WLAN meet the bandwidth requirement of the application. Table 3.1 given below shows lost frames during the handoff transition area for the received stream. ASST (in dBs) -90 -89 -88 -87 -86 -85 Lost frames_100kbit/s 13.3 5 3 0.67 0 0 Lost frames_300kbit/s 38 28 4 0.33 0 0 Table 3.1 Frames lost corresponding to ASST [5] Based on the results obtained and subjective testing, the optimal value for UDP based streaming is chosen as -86dB. Firstly by introducing EL[k], the algorithm adapts to the application requirements and reduces unnecessary handovers. Secondly, there is an improvement on the average throughput for user because MT prefers to stay in WLAN cell as long as possible. However, packet delay grows due to the critical fading impact near the cell edges, which may result in severe degradation in the user perceived QoS. This phenomenon results in a tradeoff between improving the system resource utilization and satisfying the user QoS requirements. This issue can be critical for delay sensitive applications and degrade their performance. Here ASST is tuned according to various system parameters, including delay thresholds, MT velocities, handover signaling costs and packet delay penalties. B) Algorithm on Adaptive RSS Threshold Mohanty and Akyildiz, in their paper, have proposed a WLAN to 3G handover decision method [6]. In this method, RSS of current network is compared with dynamic RSS threshold (Sth) when MT is connected to a WLAN access point. We observe the following notations with reference to fig 3.1 which shows a handoff from current network (AP) referred as WLAN, to the future network (BS), referred as 3G. Fig 3.1 Analysis of handoff process [6] * Sth: The threshold value of RSS to initiate the handover process. Therefore, when the RSS of WLAN referred to as ORSS (old RSS) in fig 3.1 drops below Sth, the registration procedures are initiated for MT’s handover to the 3G network. * a:The cell size we assume that the cells are of hexagonal shape. d: It is the shortest distance between the point at which handover is initiated and WLAN boundary. We observe the Path loss Model given by; Pr(x) = Pr (d0) + Where x is the distance between the Access Point and Mobile Terminal, and Pr (d0) is the received power at a known reference distance (d0). The typical value of d0 is 1 km for macrocells, 100m for outdoor microcells, and 1m for indoor picocells. The numerical value of Pr (d0) depends on different factors such as frequency, antenna heights, and antenna gains, is the path loss exponent. The typical values of ranges from 3 to 4 and 2 to 8 for macrocellular and microcellular environment. – Is a Zero mean Gaussian random variable that represents the statistical variation in Pr(x) caused by Shadowing. Typical std. deviation of is 12 dB. We observe the path loss model applied to the scenario. Pr (a ‘ d) = Pr (a) + Pr (a ‘ d) = Pr (a) + 10 log Sth = Smin + 10 log When the MT is located at point P, the assumption is that it can move in any direction with equal probability, i.e. the pdf of MT’s direction of motion is f = – †.’.(1) As per assumption, that MT’s direction of motion and speed remains the same from point P until it moves out of the coverage area of WLAN. As the distance of P from WLAN boundary is not very large, this assumption is realistic. The need for handoff to cellular network arises only if MTs direction of motion from P is in the range [ ] can move in both directions. Where = arctan otherwise the handoff initiation is false. The probability of false handoff initiation is using (1) is Pa = 1 – P (unfavourable event ) = 1 ‘ P ( favourable event ) = 1 – = 1 – †.’.(2) When the direction of motion of Mobile Terminal from P is, the time it takes to move out of the coverage area of WLAN cell i.e. old base station is given by time = from fig 3.1 Cos = Sec = , x = d sec Hence t = t= †.’.(3) Pdf of is f = â€Å"{† 1/(2†_1 ) -†_1†Ã¢â‚¬ _1 {0 otherwise from (3) , t is a function of i. e. t = g ( ) in [ ] [3] g(†)=dsec†/v Therefore pdf of t is given by f_t (t)=’_i’f_(† (†_i ) )/(g^’ (†_i ) ) †.’.(4) Where †i are the roots of equation t = g ( ) in [ ] And for each of these roots f†(†i)= for i = 1 and 2 f = + f = †.’.(5) Where g is derivative of g given by g = †.’.(6) = = g = t Using (5) (6), the pdf of t is given by f = †.’.(7) { 0 otherwise The probability of handoff failure is given by Pf = { 1 { P ( t ) { 0 †.’.(8) – handoff signaling delay and P ( t ) – is the probability that t when P (t ) = = = = arccos( ) †.’.(9) Using (8) and (9) we get Pf = { 1 { cos { 0 Pf = Since, †1 =arctan ( d/v†) Pf = Here, it shows that Probability of handoff failure depends on distance from point p to the boundary of the cell, velocity and handoff signaling delay †. The use of adaptive RSS threshold helps reducing the handoff failure probability as well as reducing unnecessary handovers. The exact value of Sth will depend on MT’s speed and handoff signaling delay at a particular time. Adaptive Sth is used to limit handoff failure. However, in this algorithm, the handoff from 3G network to a WLAN is not efficient when MTS traveling time inside a WLAN cell is less than the handover delay. This may lead to wastage of network resources. 3.3.2 Bandwidth based vertical handoff algorithm A Signal to Interference and Noise Ratio (SINR) Based algorithm Yang, in his paper,[7] presented a bandwidth based vertical handover decision method between WLANs and a Wideband Code Division Multiple Access (WCDMA) network using Signal to Interference and Noise Ratio (SINR) algorithm[7]. The SINR calculation of the WLAN (wireless LAN) signals is converted into an equivalent Signal to Interference and noise Ratio to be compared with the Signal to Interference and noise Ratio of the Wideband Code Division Multiple Access channel †AP =†AP [(1+ †BS/ †BS) WBS/ WAP -1] where †AP and †BS are the Signal to Interference and noise Ratio at the mobile terminal when associated with Wireless local area network and Wideband Code Division Multiple Access, respectively. † is the dB gap between the uncoded Quadrature Amplitude Modulation and channel capacity, minus the coding gain, and †AP equals to 3dB for Wireless local area network and †BS equals to 3dB for Wireless local area network, as stated by the authors. WAP and WBS are the carrier bandwidth of wireless local area network and Wideband Code Division Multiple Access links. Signal to Interference and Noise Ratio based handovers can provide users with higher overall throughput than RSS based handovers since the available throughput is directly dependent on the Signal to Interference and Noise Ratio, and this algorithm results in a balanced load between the wireless local area network and the Wideband Code Division Multiple Access networks. But such an algorithm may also int roduce excessive handovers with the variation of the Signal to Interference and Noise Ratio causing the node to hand over back and forth between two networks, commonly referred to as ping-pong effect. A Wrong Decision Probability (WDP) Prediction Based algorithm C.Chi, Cao, Hao and Liu, in their paper ‘Modeling and analysis of Handover algorithms’, have proposed a Vertical Handover decision algorithm based [8] on the Wrong Decision Probability (WDP) prediction. The Wrong Decision Probability is calculated by combining the probability of unnecessary handoff and the missing handoff. Assume that there are two networks i and j with overlapping coverage, and bi and bj are their available bandwidth. An unnecessary handoff occurs when the mobile terminal is in network i and decides to handoff to j, but bj is less than bi after this decision. A missing handoff occurs when the mobile terminal decides to stay connected to network i, but bi is less than bj after this decision. A handover from network i to network j is initiated if Pr † x l0 or bj – bi ‘ L, where Pr is the unnecessary handover probability, † is the traffic load of network i, l0 = 0.001, and L is a bandwidth threshold. The authors show that this alg orithm is able to reduce the Wrong Decision Probability and balance the traffic load; however, received signal strength is not considered. A handoff to a target network with high bandwidth but weak received signal is not desirable as it may bring discontinuity in the service. 3.3.3 Cost Function based vertical handoff algorithm A Cost Function Based algorithm with Normalization and Weights Distribution Hasswa, N. Nasser, and H. Hassanein, in their paper ‘A context-aware cross-layer archi- tecture for next generation heterogeneous wireless networks’, have proposed a cost function based handover decision algorithm in which the normalization and weights distribution methods are provided. A quality factor of network is used to evaluate the performance of a handover target candidate as Qi = WCCi + WSSi + WPPi + WdDi + WfFi where Qi is the quality factor of network i, Ci, Si, Pi, Di and Fi stand for cost of service, security, power consumption, network condition and network performance, and Wc, Ws, Wp, Wd andWf are the weights of these network parameters. Since each network parameter has a different unit, a normalization procedure is used and the normalized quality factor for network n is calculated as Wc(1/Ci) WSSi WP(1/Pi) Qi = †__________ + __________ + _______ max((1/C1),’..(1/Cn)) max(S1,’..Sn) max((1/P1),’..(1/Pn)) WdDi WfFi + ________ + ________ max (D1,’..Dn) max(F1,’..Fn) A handoff necessity estimator is also introduced to avoid unnecessary handovers High system throughput and user’s satisfaction can be achieved by introducing Hasswa’s algorithm, however, some of the parameters such as security and interference levels are difficult to calculate. A Weighted Function Based Algorithm R. Tawil, G. Pujolle, and O. Salazar in their paper presented a weighted function based[10] Vertical handover decision algorithm which transfers the Vertical handover decision calculation to the visited network instead of the mobile terminal. The weighted function of a candidate network is defined as Qi = WBBi +WDp 1/DPi+WC 1/Ci Where Qi represents the quality of network i, Bi, DPi and Ci are bandwidth, dropping probability and monetary cost of service, and WB, WDp and WC are their weights, where, WB +WDp +WC = 1 The candidate network with the highest score of Qi is selected as the handover target. By giving the calculation to the visited network, the resource of the mobile node can be saved so that the system is able to achieve short handoff decision delay, low handoff blocking rate and higher throughput. However, the method requires extra cooperation between the mobile node and the point of attachment of the visited network, which may cause additional delay and excessive load to the network when there are large number of mobile nodes. 3.3.4 ANN based vertical handoff algorithm A Multilayer Feedforward Artificial Neural Network Based Algorithm N. Nasser, S. Guizani, and E. Al-Masri, in their paper, developed a [11] Vertical handover decision algorithm based on artificial neural networks (ANN). The topology of the ANN consists of an input layer, a hidden layer and an output layer. The input layer consists of five nodes representing various parameters such as cost, RSS, bandwidth etc of the handoff target candidate networks. The hidden layer consists of variable number of nodes (neurons) which are basically activation functions. The output layer has one node which generates the ID of the candidate network of the handover target. All the neurons use sigmoid activation function. The authors have assumed the same cost function as in this work and also for ANN training they have generated a series of user preference sets with randomly selected weights. Then the system has to be trained to select the best candidate network among all the candidates. The authors have reported that by properly selecting the learning rate and the acc eptable error value, the system is able to find the best available candidate network successfully. Nevertheless, the algorithm suffers from a long delay during the training process which may lead to connection breakdown. A Method That Uses Two Neural Networks Pahlavan, in his paper, has proposed two neural [12] network based decision methods of vertical handoff. Here, only the vertical handoff mechanism is discussed. In the method for vertical handoff, an artificial neural network is used for handoffs from the Wireless local area network to the General Packet Radio Service (GPRS). The Artificial neural network consists of an input layer, two middle layers and an output layer. Mobile node does periodical measurements of RSS and five most recent samples of RSS are fed into the ANN. The output is a binary signal: The value ‘1’ leads to a handover to the General Packet Radio Service, and the value ‘0’ means that the mobile terminal should remain connected to the access point. The ANN is trained before it is used in the decision process. Training is done by taking a number of RSS samples from the access point while minimizing the handover delay and ping-pong effect. This algorithm can reduce the number of handovers by eliminating the ping-pong effect, but the paper does not provide details on how exactly the neural network is trained and why the particular parameters are taken into consideration. This algorithm also has the short coming of the algorithm complexity and the training process to be performed in advance. Summary: From the above discussion, it can be concluded that RSS based Vertical handoff algorithms can be used between microcellular and macro cellular networks. The network candidate with most stable RSS being the selection criteria. These algorithms are simple, but due to the fluctuation of RSS, they are less reliable. Bandwidth based Vertical handoff algorithms can be used between any two heterogeneous networks. The network candidate with highest bandwidth is the selection criteria. These algorithms are simple. But, due to the changing available bandwidth, these algorithms are less reliable. Cost function based Vertical handoff algorithms can be used between any two heterogeneous networks. Here, the inputs are various parameters such as cost, bandwidth, security etc The network candidate with highest overall performance is the selection criteria. These algorithms are complex. But, due to the difficulty in measuring parameters such as security etc, they are less reliable. ANN and Fuzzy logic based Vertical handoff algorithms can be used between any two heterogeneous networks. Here, the inputs are various parameters such as RSS, cost, bandwidth, security etc depending on different methods. The network candidate with highest overall performance is the selection criteria. These algorithms are very complex. But, due to training of system, they are highly reliable. ‘ Chapter-4 Algorithms and Methodologies 4.1 Variance based vertical handoff algorithm Proposed algorithm is variance based algorithm which calculates the variance of parameters such as delay, jitter, bandwidth and packet loss for various networks such as UMTS,WLAN,Wimax and the network with most of the parameters with minimum variance being selected. In our proposed algorithm, handoff metrics such as delay, bandwidth, jitter, packet loss etc are included Fig 4.1 Flow Chart of variance based algorithm Variance = ‘(x-†)’^2/N , where x is any metrics such as delay, bandwidth, jitter etc and † is its mean of a set of samples of the particular parameters. N is set of samples. In this algorithm, whenever the signal strength of a mobile terminal drops below threshold ,there is request from mobile terminal for handoff to the network which is accessible. The algorithm checks whether the visitor network available or not, if visitor network is available ,it will broadcast required parameters such as packet delay, jitter, packet loss and bandwidth etc. The variance of the broadcasted parameters are calculated based on the number of samples received for each parameter. Then, the candidate network (Visitor network) having most of the minimum variance of the parameter is selected. In this case, variance of delay, jitter, packet loss and bandwidth are considered for the set of 100 samples received. Here, variance of packet delay is calculated as: †_d^2 = ‘(D-†_d)’^2/N Where, †d is the variance of the packet delay parameter, D is the packet delay at that instant ,†d is the mean of the packet delay values received and N is the total number of samples for packet delay parameters(which is 100 in this case). Similarly, variance of bandwidth is calculated as: †_B^2 = ‘(B-†_B)’^2/N Where, †B is the variance of the Bandwidth parameter, B is the Bandwidth at that instant ,†B is the mean of the bandwidth values received and N is the total number of samples for bandwidth parameters(which is 100 in this case). In the same way, variance of Jitter is calculated as: †_J^2 = ‘(J-†_J)’^2/N Where, †J is the variance of the Jitter parameter, J is the Jitter at that instant ,†J is the mean of the jitter values received and N is the total number of samples for jitter parameters(which is 100 in this case). In the same way, variance of Packet loss is calculated as: †_P^2 = ‘(P-†_P)’^2/N Where, †P is the variance of the packet loss parameter, P is the packet loss at that instant ,†P is the mean of the packet loss values received and N is the total number of samples for packet loss parameters(which is 100 in this case). Out of these variance †_d^2 , †_B^2, †_J^2, †_P^2, the candidate network most of them with minimum values will be selected. Score† =’arg’_(i=1)^MMAX(min †_d^2 , †_B^2, †_J^2, †_P^2) The candidate network which satisfies above equation is selected. Where M is the number of candidate network. 4.2 SNR based vertical handoff algorithm Proposed algorithm is an SNR based algorithm which calculates the value of SNR of parameters such as delay, jitter, bandwidth and packet loss for various networks such as UMTS, WLAN, Wimax with the network with maximum SNR being selected. In our proposed algorithm, handoff metrics such as delay, bandwidth, jitter, packet loss, etc are included Pages: Page 1, Page 2