Literature Review: Wireless Sensor Networks

Literature Review: Wireless Sensor Networks CHAPTER 2 To complete this project, a lot of literature reviews have been done. These include many case studies from past to recent research and general understanding towards the theory behind each technology. Articles, journals, books, previous projects and internet have served as sources of literature reviews. Some major case studies are described below. 2.1.1 Case study 1 Case study towards paper Integration of RFID into Wireless Sensor Networks: Architectures, Opportunities and Challenging Problems (2006) [1] In this paper, Lei Zhang and Zhi Wang propose three different forms of network architecture based on integration of RFID and wireless sensor network, The three architecture are Heterogeneous network, Distributed reduced functional sensor reader network, and Mini node network. Heterogeneous network architecture uses 802.11b/Wi-Fi technology as its platform. In Physical layer, 802.11b/Wi-Fi uses the unlicensed 2.4 GHZ band and Discrete Sequence Spread Spectrum (DSSS) technique. Its maximum data rate can reach to 11 Mbps. In MAC sub-layer, 802.11b/Wi-Fi uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) scheme, which will improve the efficiency of network. This architecture is good for real-time operation but limited range. Distributed reduced functional sensor reader network architecture uses ZigBee protocol as its platform. The reasons are ZigBee uses lower power consumption in physical layer and MAC layer, more reliable and low cost. This architecture is good for wide range but no real-time requirement. The last architecture which is the Mini node network architecture uses IEEE 802.15.4/ZigBee standard protocol as its platform since there is little data flow and reduced cost. The mini node is actually the Mica nodes which allow communication between each mini node. This architecture is specially fit for industrial security and remote condition-based maintenance system, Figure 2.1 below describe remote condition-based maintenance systems based on the application of Mini node network architecture. By using this architecture, the reader from the forklift will sense signal from each mini node and will move toward the signalled mini node to perform tasks like move rotating parts of a machine automatically. Figure 2.1: Fork lift operation dispatching in a factory [1] Case study 2 Case study on paper Smart Home Mobile RFID-based Internet-Of-Things Systems and Service (2008) [2] Mohsen Darianian, Martin Peter Michael introduce a RFID reader system architecture for a home comprised of several readers in master slave architecture. The communication protocol between the readers and tags is based on RFID standard protocols like UHF. As shown in Figure2.2 below, the system consists of following reader components: Master Reader (MR), a number of Slave Readers (SR), and Mobile RFID (MRFID) Reader The Master reader is a conventional powerful fixed reader with a direct fixed or wireless connection to the smart home server. It starts the read process of slave readers and power up passive tags for reading process. In addition, this master reader also acts as the so-called RF Energy Generator for mobile RFID reader so that the mobile RFID reader can have lower consumption of power. The Slave reader acts as middleware for capturing tag ID information tags which are not accessible by the direct radio transmission of the master reader. Slave readers will be integrated in the home appliances. Since location of the slave readers is known by the system, it is good for localization of tags As for the Mobile RFID reader, in this paper, it has been improved so that it does not consume a lot of energy. The mobile RFID reader will use the proposed architecture so-called RF Energy Generator to be powered up by master reader or slave reader. Thus, these mobile readers will act like passive readers. In this paper, Mohsen Darianian, and Martin Peter Michael have apply the proposed system architecture as described above to create a smart home which apply wireless concepts along with RFID technologies for creating services almost everywhere in a house. It applications include control electrical appliances, home tele-monitoring, and give intelligent suggestions inside the house automatically and wirelessly. Figure 2.2: Smart Home using RFID and WSN [2] Case study 3 Case study on Paper Bus Management System Using RFID in WSN by Ben Ammar Hatem and Hamam Habib (2009) [3] In this paper, intelligent bus tracking application applying integration of RFID and wireless sensor network technology to monitor whether the bus will be arriving on time, early or late inside the bus station is introduced. The design approach is proposed. As shown in Figure 2.3, first, each bus will has its own UHF tag. Next, Entrance and exit doors will be equipped with an RFID reader, antennas and motion sensors. When a bus enters or exits the station, the RFID reader will send its identification to the central computer where the event is displayed on a Map. Finally, a software application on the control station keeps track of the entrance and the exit of buses and updates the displays related to those buses with useful information. The communication will be wireless using ZigBee protocol. To execute this proposed architecture, they choose to use Ultra High Frequency generation 2 (UHF Gen2) RFID which operates between 860MHz to 960MHz bandwidth. UHF is better suited for reading tag attached to buses. It uses backscatter technique to communicate with the tag and provides higher read range compared to HF and LF technology. As for the antenna, they used Alien circular antenna to read RFID tags to improve orientation of reading. Two antennas are used in each gate, to communicate with tags. One is used for the emission of energy to the tag and the other receives energy back from the tag. The display is using the LCD and LED technologies. By completing this proposed system, it is hope to provide a smart solution for managing the bus schedule in the bus stations and offering helpful information to passengers. Problems like under employment of buses fleet and long waiting time at the bus station can be minimised. Case study 4 Case study on paper Intelligent Traffic Management System Base on WSN and RFID by Lejiang Guo, Wei Fang, Guoshi Wang and Longsheng Zheng (2010) [4] This paper introduces Intelligent Transportation System (ITS) base on RFID and WSN, and discusses the hardware and software design principles of the system. Figure 2.4 shows the ITS system architecture. It consists of Access and Terminal Layer, Application Processing Layer, and Data storage and access management. The Access and Terminal layer mainly completes information exchange between each subsystem of ITS. Application Processing Layer will be responsible for processing the information. And lastly the Data storage and access management will be the data management system for the ITS system. As for the composition of the system, RFID tags and sensor nodes are used to keep stored in the monitoring area. RFID reader is used for the base station. At the same time, the sensor nodes send the data after its transfer to the local PC or remote network. RFID can be used for dereliction of duty as an intelligent base station device for RFID and data WSN systems Integration. In the network, the system consists of five types of facilities which are Base Station, Sensor nodes, RFID Tags, Device reader and Center Data Platform. Zigbee protocol is implemented in this system architecture. Figure 2.5 show how the sensor nodes are deployed and communicate to each other. As for the data communication middleware, advanced web Service architecture is implemented. The reason is web service is the most advanced platform for distributed applications, by which it not only can achieve basic distributed application, but also improve fault tolerance. Messaging middleware is using XML format for the transmission of information. Geographic Information System (GIS) is also combined in the system. GIS is based on one of the technologies supported by Public Security Traffic Management GIS platform. GIS is used to process all information associated with visual processing, to provide simple and direct for visualization information interface. By utilizing the application of ITS based on combination of RFID and WSN. The real-time traffic management system can provides the basis for efficient data monitoring. Second, the system uses the heterogeneous adaptive network architecture for road monitoring will provide a more flexible way, efficient, reliable system communication architecture for traffics management system Case study 5 Case study on paper Innovative Application of RFID Systems to Special Education Schools by Shu-Hui Yang and Pao-Ann Hsiung (2010) [5] In this paper, the uses of RFID system innovatively broaden. Application of innovative Radio Frequency Identification (RFID) systems has been incorporated to special education school campus to improve the teaching and learning and control process in special education schools. For the Implementation Platform and Architecture, the main RFID campus system was implemented using the YesTurnkey technology, which includes four parts, namely front-end RFID middleware server, front-end RFID application server, backend database server, and backend RFID application server. Front-end RFID Middleware Server consists of YesTurnkey Asset Tracking Manager which is a manager of all network resources that includes the set of active RFID readers installed on campus and RFID Processor DLL that processes RFID data. Front-end RFID Application Server is a server which used by the Type 1 (Direct-Connected) RFID scenario windows applications. Backend Database Server implemented the Microsoft SQL Server. And finally, Backend RFID Application Server: which manages the execution of two kinds of applications which are YesTurnkey WiNOC (Wired/Wireless Network Operations Center) Web Application and Type 2 (LAN-Based) RFID Scenario Web Application. However, five of the innovative works are focused, including student temperature monitoring (STM), body weight monitoring (BWM), garbage disposal monitoring (GDM), mopping course recording (MCR), and campus visitor monitoring (CVM) by applying the RFID system technology. Basic operation for mopping course recording (MCR) system will be described below. (Swab with the reader is moving across tag) As shown in Figure 2.6, first, they patch up of a mobile pedestal, an artificial plastic floor with embedded passive RFID tags, and a real mop equipped with a Bluetooth passive RFID reader. The mobile pedestal carried a laptop for displaying the real time status of how a student is performing the cleaning job and a projector connected to the laptop, which could project a black, dark grey, light grey or white image on the artificial floor, which represented dirty, little clean, quite clean, and clean. By using this MCR, teacher can monitor these special education students so that the students will learn to complete their task better. As can be seen, by using this RFID technology, outcomes shown above have truly give benefits not only to teacher but also the student. Research is still ongoing to include RFID technologies in teaching method and materials. Summary of the case studies Theories behind this project This section explains general theory on the technologies involve in this project. The theory and technology involve include Wireless Sensor Network (WSN), Radio-frequency identification (RFID), Integration of WSN and RFID and Visual Basic Programming (VB). 2.2.1 Wireless Sensor Network (WSN) A Wireless Sensor Network is a self-configuring network of small sensor nodes communicating among themselves using radio signals, and deployed in quantity to sense, monitor and understand the physical world such as temperature, pressure, humidity and more. Figure 2.7: WSN Sensor Node 2.2.1.1 Wireless Sensor Network (WSN) Topology Wireless sensor network topology show how each sensor node inside a wireless network are connected. Some of the WSN topologies are like star, mesh and cluster/tree. They are shown Figure 2.8 below. Basic WSN topology is the star topology in which each node maintains a single, direct communication path with the gateway. To increase wireless coverage, cluster/tree topology can be used although it increases complexity. Finally, although network latency may be experienced, mesh topology is especially good in increase network reliability. [6] Figure 2.8: WSN network topologies 2.2.1.2 Wireless Sensor Network (WSN) components A wireless sensor network may consist of the following components: power supply, microcontroller, wireless communication, sensor, local storage, and real time clock systems. Some components may be optional and are depend on the function purpose. The main idea is that the sensors are connected to a tiny computer that coordinates the measurement, pre-processes, stores and delivers the information. Wireless Sensor Network (WSN) characteristics This section describes the behavior or the uniqueness of wireless sensor network. Some of them are: harvest or store limited power, Able to withstand harsh environmental conditions, able to adapt with node breakdown, nodes mobility, dynamic network topology, heterogeneity of nodes, large scale of deployment, unattended operation, and lastly, node capacity is scalable and only limited by bandwidth of gateway node. Wireless Sensor Network (WSN) protocols There are a lot of wireless sensor network protocols in market nowadays. Some of the well- known WSN protocols are Bluetooth, WiFiZone, IEEE and ZigBee. Choosing the wrong protocol may cause severe inefficiency and prevent the WSN to accomplish user need. The protocol will affect energy dissipation, system cost, Latency and Security. Thus, it is very important to choose the best protocol for a system as it strongly impact on system performance. Wireless Sensor Network (WSN) platform Wireless sensor network platform basically include the hardware design, modular design, smart sensor interface, software design, and operating system. The hardware designs include super node, simple node and gateway. All these design have to follow several standardized specification developed by IEEE, Internet Engineering Task Force, and International Society of Automation. Modular design has to be flexible and expandable for various applications. Smart sensor interface has to equipped with plug and play modules. Important topics to be considered in software design include security, mobility and middleware which allow communication between software and hardware. And finally, operating system has to be compatible with TinyOS as TinyOS allows easy establishment to wireless sensor network. Radio-frequency identification (RFID) RFID is a means of identifying a person or object using radio frequency transmission. Mainly, RFID consists of three parts which are reader, tag and also host computer. There are also various types of reader and tags depend on their uses. Figure below show basic operation of a RFID system. First, to read data for tag, tag is move and enter RF field of reader through antenna. Then, RF signal from antenna will power the tag to allow the tag to transmit its ID and data back. Reader will then capture the data and send them to the computer for displaying. To write data to the tags, we just write the data into the computer, and the reader will take the data from the computer and transmits them into the tag via the antenna. Figure 2.9: Basic Operations of RFID 2.2.2.1 RFID reader RFID reader is also called as RFID interrogator and it is used to read/write data from/to tags. It can operate on single or multiple frequencies, and perform anti-collision processing. There is also a hybrid RFID reader which can read bar code. There are mainly three types of RFID reader which are fixed, hand-held and mobile reader. Each reader has their own uniqueness. RFID reader consists of components like receiver, transmitter, oscillator, controller/processor and input/output port. The receiver holds an amplifier and a demodulator. Transmitter has a modulator and power amplifier. Oscillator is used to provide carrier signal to modulator and a reference signal to demodulator circuits. Then, the controller/processor will perform data processing and communicates with external network. And lastly, input/output port is connected to the antenna. 2.2.2.2 RFID tag RFID tag consists of RFID chip, antenna and power source. RFID chip consists of modulation circuitry, control circuitry, processor and memory. Modulation circuitry can change the signal from reader to include data to be transmitted back to the reader. Control circuitry control internal function under the command of processor. Processor interpret signal from reader and control memory storage with retrieval. And memory serves as writable and non-writable data storage. Antenna is only used by Ultra high frequency and Microwave frequency tags. Low frequency and High frequency tags will use induction coils. As for power sources, the tags can be divided into three types which are active tags, semi-passive tags and passive tags. Active tags have internal power source. Passive tags draw power from reader. And Semi-passive tags are battery-assisted but communicated by drawing power from reader. Integration of WSN and RFID Wireless sensor network (WSN) is used to sense and monitor various parameters in the environment while RFID is used to detect presence, location and identification of objects. By integrating these two technologies, they will provide a significant improvement on monitoring application. The basic idea of integration of WSN with RFID is to connect the RFID reader to an RF transceiver, which has routing function and can forward information to and from other readers wirelessly. RFID will act as a sensor in the WSN. With combination of RFID and WSN, monitoring and tracking application can be done not only outdoor but indoor also (with obstacle). The coverage can also be improved depends on the specification of WSN platform used. Visual Basic Programming (VB) Visual Basic is a programming language and environment developed by Microsoft which is based on the BASIC language. Visual Basic is commonly used to develop graphical user interface. Visual Basic was one of the first products to provide a graphical programming environment for developing user interfaces. Since it uses graphical programming environment, we can be sure to increase the efficiency in design the graphical user interface.

The Evident Existence of Races

Many sociologists believe that ‘races† do not exist therefore have to find alternative groupings to study racism or patterns of racial disadvantage in the United Kingdom. There exist many differing theories but no finite method of determining the true cause of racism. This dissertation will outline the different theories used by sociologists and attempt to show the patterns of ethnic disadvantage present in Britain. Racism is thought by many to be the notion that some ethnic groups are naturally superior to others. The Oxford Dictionary†s definition of the word ‘race† is ‘ A group of persons of common stock† ‘Human abilities are determined by â€Å"race†Ã¢â‚¬ . Although ‘Race† and Racism are defined in the oxford dictionary sociologists claim that ‘races† do not exist. They have considered the work of human biologists who in turn have studied the genes of many individuals that are said to be associated with different ‘races†. The results of these studies show that there is no distinctive gene that defines which ‘race† a person belongs to. Blood groups have been examined and results show that while some ‘races† have higher tendencies to certain blood types, no one ‘race† has been found to have one particular blood type unique to their origin. Due to there being no conclusive biological evidence biologists refer to different ‘races† as different populations. Any cultural differences are said to be ethnic differences, not differences in race. There is a belief that if ‘race† does not exist then sociologists can†t rightfully use the term in their study of different populations. It is due to this belief that they must find alternative ways of analysing population differences. The history of ‘race† is important to examine in the attempt to show why ordinary people, known as actors, still think that ‘race† exists. Racism is thought to have always existed. The Romans considered slaves as being inferior to themselves, but there has been no scientific evidence to support claims of superiority. In the early 18th century until early in the 19th century there was a progressive belief that there was basic similarity between all men, that social differences were due to the environment. This view was overridden by the rise of scientific racism where all social differences found previously were labelled and explained as ‘natural†. But again ‘race† has never been a scientific concept. It was due to this that in the 20th century political/moral reasons forced scientific racism into decline and was eventually replaced by cultural racism, which shares the same beliefs. Racism is thought to be a set of beliefs and racial discrimination the set of practices that are synonymous with these beliefs. There are several contrasting views of racism and racial discrimination. The functionalist model looks upon it via the perspective of ‘race† relations, that racism exists due to the creation of bad relations between ‘races†. Due to ‘race† not existing, functionalists study situations that are apparent in society. They look at events which actors define as racial, and by this expedient they examine the processes of racialism. John Rex a radical weberian believes in the conflictional view that competition over scarce resources in different markets is the cause of conflict between Afro-Caribbean†s, Asians and whites in relation to employment and housing (Bulmer et al, 1999:335). He say†s that it is not due to the lower wages which ethnic minorities receive. The Marxist perspective focuses on labour relations. An ideology masking contradiction of capital between capitals† need for free labour and nationalism. Robert Miles, a hard line Marxist believes that class is the determining factor and all inequalities derive from class inequalities. Miles is very much alone in his claim but gives the example of the white working class fearing immigrants due to a rise in unemployment levels and a decline in standard of living. However, Miles states that the immigrants were not the cause of this. He claims that capitalism was. He states many find this hard to see because: ‘We are offered definitions and theories of racism which are so specific to the history of overseas colonisation (that is specific to the domination of ‘white† over ‘black† as so many writers express it) that they are of little value in explaining any other non-colonial) context† (Miles, R (Bulmer et al, 1999:344)) Another Marxist theory focuses on wider relations. ‘Race† has no reality but can be used in analysis, this theory is concerned with racial politics and how they may be independent of class. Marxists who follow this belief say that groupings and conflicts intersect, and may not actually be connected with class. With the term ‘race† being seen as invalid by many people the question has arisen. Are we better to talk about ethnicity rather that ‘race†? Ethnicity is a sense of identity to a group that shares a common history. Ethnic groups are also held together by ties of language, culture and group spirit that are now referred to as nationalism. There are also territorial ties, although many ethnic groups had previously left their homeland they still share a common geographical link. The term ethnicity is often confused with ‘race†, again when talking about ethnicity there have never been boundaries whether cultural or geographical that clearly states the limits of ethnic groups, even though many believe ethnicity is naturally determined. The idea that ethnicity is ‘natural† is said to be ‘wrong†. Ethnic differences are cultural, we all have an identity, though we may not always be conscious of it. There has recently been a revival of ethnic differences followed by reactions to discrimination and racial disadvantage. An example of this is Afro-Caribbean†s beliefs of what Britain would be able to offer them, these beliefs have changed due to certain types of discrimination and disadvantage. Cultural and religious issues can now be seen as more significant than economic inequalities. There are however some problems with ethnicity. Emphasis is placed on difference and cultural issues of power and inequality, therefore, ethnic groups may be seen to be fixed racial groups with another identity. Racial disadvantage in the United Kingdom is visible in many different areas of the community. Employment, education and crime are just a few examples. Throughout employment, horizontal segmentation can be seen to be apparent via clustering. Ethnic minorities are more likely to work for themselves, graduates from these backgrounds tend to do relatively badly, many Asians are self-employed and Afro-Caribbean†s are largely recruited to the private sector. This shows that ethnic or racial factors are involved in stratification in Britain. Within the generalisation that, ethnic minorities are treated less equally, individual successes and inter-group variations are present. This is shown by vertical segmentation, Afro-Caribbean†s being placed at lower levels of employment than Asians. When the ‘The Race Relations Act ‘ was amended in 1976 The Commission for Racial Equality was established to promote racial harmony. This was to try to counter the acts which had been enforced prior to the Race Relations Act of 1965. Such acts, for instance, as the British Nationality Act 1948 and the Commonwealth Act 1962 which where more concerned with restricting immigration than trying to promote good ‘race† relations. In the context of the recruitment of employees, the Race Relations Act 1976 stated that it is unlawful to discriminate: By a company giving racial instructions to a personnel officer or an employment agency. In relation to terms of pay. By rejecting an applicant or refusing to consider him for the post on the basis of race. These laws were enacted in order to try to increase equality in employment. As a mechanism to bring about change to employment rights the Commission for Racial Equality has made extensive recommendations to successive governments including a move to make ethnic monitoring compulsory for all employers with an excess workforce of 250. In the belief that ethnic monitoring is essential for progressing to racial equality. Racial disadvantage has also been found to be present in the theatre of education. Before 1973 it was known that white pupils topped the performance list with Asians and Afro Caribbean†s coming further down. The differences in levels of performance were considered to be related to the duration of the pupils† stay in the UK. Newcomers would have experienced problems adapting to a new way of living and may even have encounter communication problems. Moving on to early 1970†³s – 1980†³s the focus of discrimination in education moved to examine the effects of class and the school at which they enrolled. It was found that ethnic minorities are more likely to go to an underachieving school than their white counterparts due to their class framework, lower income and location. Curriculum was also thought to be a cause of the poor academic findings relating to ethnic minorities. The syllabus that the schools were offering was not relevant to children from ethnic backgrounds, a ‘white curriculum† concentrated on ‘white history† and the history of Britain. This was modified to give a wider education on the history of ethnic countries in an attempt to make studies more relative for ethnic minorities. With these problems tackled, education monitoring in the 1980†³s showed children from ethnic backgrounds to be improving at a faster rate than white children of the same age. Schools support the right of all children to receive quality education and fair treatment. The governing body of education aims to ensure that no one receives less favourable treatment on the grounds of race or any other social/cultural labels. It is believed that racism can be learned from an early age but to control this unwanted learning the children must be taught respect for other people in-order that they might learn ‘rights from wrongs† ‘If segregation of the sexes or races prevails, if authoritarianism and hierarchy dominate the system the child cannot help but learn that power and status are dominant factors in human relationships†¦.If the teacher and the children are each respected units, the lesson for respect for the person will easily register† The Race Relations Act of 1976 again places barriers on education by stating that; ‘By excluding a pupil from the establishment or by treating him unfavourably in any other way† is unlawful. Now in higher education a higher percentage of ethnic children stay on after 16 years old. This is encouraging but fewer now enrol at university, on academic courses and more drop out. This however can no longer be explained due to lack of adjustment since most were born here and therefore need no time to adjust to the a new community or learn a new language. Within the Criminal Justice System racial discrimination also exists. It is understood that black people are far worse off at every stage of law enforcement. They are more likely to be stopped by Police, charged with serious offence, prosecuted, convicted, and imprisoned. They are less likely to be given lenient treatment for example, fined, put on probation, or allowed bail. It has been declared that in 1997 the United Kingdom had one of the highest levels of racist orientated attacks in Europe, and that 1 in 3 British citizens classed themselves as racist (Thompson B., Roots of poison). Racial hatred and prejudice is an example of extremism, when cultural differences start being connected to ‘race† a persistent hatred can occur. Racism, it is argued, is a specific form of discrimination usually associated with skin colour and ethnicity. It involves the use of power of one group over another. When this power is unequal it enables those that share a particular culture to deny others access to opportunities, hence treat them in a racist way. As well as being more inclined to be the perpetrators of crimes, ethnic minorities are also prone to be the victims. These crimes are not however due to ethnic background but are due to the social background of their class. Despite this, people are sometimes ignorant to this fact and state that ethnic crimes are more apparent because they are of an inferior race. A Report by Sir William Macpherson that examined the Lawrence case (in which it was claimed that the police neglected their job because the victim was ‘black†), was published on 24th February 1999. In the report, which was presented to the Government and to the Home Office, McPherson revealed that the problems, which occurred during the case, were the result of Institutional Racism defined as; ‘The collective failure of an organization to provide an appropriate and professional service to people because of their colour, culture or ethnic origin† It was said that institutional racism can not be used in the labeling of individuals but must be a label that is associated with the organization as a whole. It is due to the finding of racial disadvantage, that the police have set up ‘Operation Athena† to tackle the problems outlined in the report. The operation aims to improve prevention, awareness, communication, response and the identification of needs in the context of ethnic minorities. The three examples of employment, education and crime are only a selection of the sectors of the community that show racial disadvantage. Although there is no finite definition of ‘race† there has been continual work to improve the social conditions for ethnic minorities. It is hoped that in the future there will be racial harmony between all populations and that ‘true† equality will be gained.

Compare and Contrast the Approach to Studying Childrens...

TITLE Compare and contrast the approach to studying children’s friendships taken in the Bigelow and La Gaipa (1974) study with that taken by William Corsaro. Friendship means different things to different people in different cultures. Friendship is also different from other kinds of relationship such as love, family and professional. The influential power on people’s behaviour, style, ideas and life is dominant and remarkable and therefore worthwhile for scientific investigation. This essay will compare and contrast the academic research of three dominant and pioneer scientists on the development psychology discipline and especially in the field of children’s expectations and children’s understanding of†¦show more content†¦In contrast Corsaro emphasised in what friendship means in particular places at particular times and how children communicate each other in real life conditions in their natural environments. Bigelow and La Gaipa used the â€Å"content analysis† for they studies. They took a sample of 480 formal interviews from 8 schools (30 boys and 30 girls from each school, between the ages of si x and fourteen) in written, text format with questions concerning the nature of the friendship between them and their best friend of the same sex, about what they felt were important on these relationships, about what they expected from them and what were the differences between their best friends and other friends and acquaintances. When the written essays were compiled they were all compared against a pre-selected, by the researchers, list of features (relevant to this research study), such as loyalty, genuineness, commitment and admiration, in order to find possible feature similarities (known as a frequency count) between the children’s friendship expectations and the pre-selected list. Finally, Bigelow and La Gaipa made a general list of these frequency counts depending on how many times each of the children’s friendship expectations occurred in their written essays in order to the changing nature of friendship expectations, between the different

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