Case study on kerry group Essay

Introduction As part of my business management assignment I have been asked to investigate and evaluate the internal and external environment of an organization and the impact of change on an organization I intend on outlining the purpose, mission, vision , objectives and structure of this organization, explain the relevance of the type of structure. Do a pest and swot analysis and evaluate the impact of change on the organization , I will be completing this assignment with the aid of the website , Kerryfoodgroup.com the internet and my class notes. Aims The aims of this assignment are to ensue I cover the following aspects: Relevant information appropriately presented  Understanding and knowledge of chosen topic clearly demonstrated Present relevant data and statistics that support my work  Comprehensive evaluation of topic clearly demonstrated  Conclusions and recommendations bibliography Organisation types I am going to explore the following organisation types: Sole Trader Private limited Company Public limited Company Co-Operative Sole trader A sole trader is a type of business entity that allows one person to be solely responsible for the financial dealings of the business. The benefits and disadvantages of being a sole trader Advantages You are your own boss . Set your own working hours. Pick your rate of pay. Easy to set up. This form of business ownership has fewer regulations than other systems of ownership do. And another major benefit of operating as a sole trader is the ability to exert full control over the business Disadvantages Unlimited liability No sick pay. All pressure and responsibility is on you. No one o cover you if something happens Income tax 20-41% No one to share decision’s Suffer all losses Private Limited Company Private limited companies are viewed as corporations under the law and share several common characteristics with all corporations. However, private corporations are owned and operated by a small group of people. Because of their structure, private limited corporations operate under a set of limitations not imposed on public corporations. Advantages A private limited company is run by a small group, Many of them members of a single family, that wishes to limit the influence of outsiders on its company. Because private limited companies are run by a small group, they are usually not subject to takeovers and other challenges faced by public companies. The minmum required to set one upis 1 person and the max is 99. Disadvantages Profit Sharing Taxes Lack of privacy, information concerning the company is made public. Public limited company A company whose shares are traded on a stock exchange and can be bought and sold by anyone. Public companies are strictly regulated, and are required by law to publish their complete and true financial position so that investors can determine the true worth of its stock . Also called a plc Facebook is a reality formed plc . Advantages There is limited liability for the shareholders. The business has separate legal entity. There is continuity even if any of the shareholders die. These businesses can raise large capital sum as there is no limit to the number of shareholders. The shares of the business are freely transferable providing more liquidity to its shareholders . Disadvantages There are lot of legal bits and pieces required for forming a public limited company. It is costly and time consuming. In order to protect the interest of the ordinary investor there are strict controls and regulations to comply. These companies have to publish their accounts. The original owners may lose control. Public Limited companies are huge in size and may face management problems such as slow decision making and industrial relations problems. Co-Operative  A co-operative is a group of people acting together to meet the common needs and aspirations of its members e.g the Credit union, sharing ownership and making decisions democratically. Co-operatives are not about making big profits for shareholders, but creating value for customers this is what gives co operatives a unique character, and influences our values and principles. Advantages It is usually inexpensive to register a cooperative. All members and shareholders must be active in the cooperative. Shareholders have an equal vote at general meetings regardless of their shareholding or involvement in the cooperative. Members, other than directors, can be under  18, though these members cannot stand for office and do not have the right to vote. Shareholders, directors, managers and employees have no responsibility for debts of the cooperative unless those debts are caused recklessly, negligently or fraudulently. A cooperative is owned and controlled by its members, rather than its investors. Disadvantages There must be a minimum of five members. There is a usually a limited distribution of surplus (profits) to members/shareholders and some cooperatives may prohibit the distribution of any surplus to members/shareholders. Even though some shareholders may have a greater involvement or investment than others, they still only get one vote. Active and direct involvement of members/shareholders in the cooperative. These bullet points and definitions where all found in my class notes and I also used www.cro.ie Kerry Foods Group The company I am going to focus on will be Kerry foods group the history of the organisation traces the evolution and growth of Kerry Group from its modest beginnings in the south west of Ireland some 30 years ago into a successful, publicly traded, multinational corporation and leading player in the global food industry. Having commenced operation from a green field site in Listowel, Co. Kerry in 1972, the Kerry organisation has realised sustained profitable growth with current annualised sales of approximately â‚ ¬5.8 billion, Kerry Group today is a world leader in food ingredients and flavours serving the food and beverage industry, and a leading supplier of added value brands and customer branded foods to the Irish and UK markets. Kerry has grown to become one of the largest and most technologically advanced manufacturers of ingredients and flavours in the world. Spanning all major food categories, Kerry’s core technologies and global resources in culinary, dairy, lipid, meat, cereal, sweet and beverage systems and flavours provide innovative, practical product solutions to food manufacturers and food service companies. Purpose Kerry Foods operates in Ireland and the UK. they market there own brands across a wide range of categories and supply supermarket private labels in selected areas. they also have become one of the leading chilled foods companies in the geography through: A strong portfolio of brands, in which they continue to invest and grow Close working relationships with retail customers to develop mutually successful, private label business An unrivalled national service to the independent convenience sector, in both the UK and Ireland Mission statement Kerry Group will be: – the world leader in food ingredients and flavours serving the food and beverage industry, and – a leading supplier of added value brands and customer branded foods to the Irish and UK markets Through the skills and wholehearted commitment of ther employees, we will be leaders in our selected markets – excelling in product quality, technical and marketing creativity and service to our customers We are committed to the highest standards of business and ethical behavior, to fulfilling our responsibilities to the communities which we serve and to the creation of long-term value for all stakeholders on a socially and environmentally sustainable basis. Vision Group Goals & Long Term Targets †¢ Group revenue: +2% to +4% (LFL) volume growth †¢ Margin: 10% Group margin in 5 years †¢ Adjusted EPS* 10%+ †¢ ROAE* 15%+ and CFROI 12%+ Objectives Kerry’s Sustainability Programme represents a journey of continuous improvement – an ongoing process and strategy to secure sustainable growth. Sustainability is at the heart of our business strategy and enshrined in our corporate mission statement.As a world leader in ingredients & flavors and as a major consumer foods organization in Europe, Kerry aims to conduct its business in a responsible and sustainable manner. This demands a holistic approach to Group activities involving close liaison with our customers, suppliers, regulatory authorities, employees and other relevant stakeholders.Our Kerry Group Sustainability Council appraises, directs and provides leadership in promoting industry best practice sustainability program throughout the Group. Its membership includes Directors of Group functions with responsibility for all pillars of Kerry’s Sustainability Programme. Structure of the organization Business structure The Group is divided into several divisions: â€Å"Kerry Ingredients & Flavours† is the largest division producing over 15,000 ingredients, flavours and integrated solutions from more than 125 manufacturing sites worldwide. It claims to have become the largest and most technologically advanced provider of technology-based ingredients, flavours and integrated systems. â€Å"Kerry Foods† supplies added-value branded and customer branded food products to supermarket chains, convenience stores and independent retailers across the UK and Ireland. It has 15 manufacturing facilities all in Ireland and the UK. Products include sausage, sliced bacon, sliced meats, pastry products, ready meals, ready-to-cook products, savoury snacks, cheese, cheese snacks, dairy spreads, low-fat spreads, UHT products, home-baking products, salads, sandwiches and fruit juices. Consumer branded products include – in Ireland: Denny, Galtee, LowLow, Dairygold, Cheestrings, Charleville Cheese, Shaws, Coleraine, Golden Cow, EasiSingles, Dawn, Roscrea, Kerrymaid, Golden Olive, Mitchelstown, Calvita, Ballyfree, Move over Butter and Freshways – in the UK: Richmond, Wall’s,  Mattessons, LowLow, Cheestrings, Pure, Mr. Brain’s, Porkinsons, Bowyers, Lawsons, Green’s and Homepride. â€Å"Kerry Agribusiness† is headquartered in Charleville, Co. Cork, and works with the Group’s 4,000 milk suppliers in Ireland, to produce milk and related dairy products. Why have structures? Because it allows each sector to oranise itself. All businesses have to know what to do A clear structure makes it easier to understand the organisations objectives Organization chart What is a organisation chart? Companies use the organizational chart to pictorially depict their prevailing hierarchies, work flow and authority-responsibility diagrams. Small companies use flat organizational charts and large companies use tall organizational charts. Function The main purpose in drawing an organizational chart is to visually represent employee structures of the organization. One glance at the chart tells the viewer of all reporting to a particular employee and to whom he is answerable for work-related matters. Features A tall organizational chart is one that is shaped like a pyramid. There are several layers and tiers of employees. This structure is narrow and the top and broad at the bottom. A flat organizational chart is wide and expansive all throughout. More often than not, the employees report directly to the top management. This is pictorially depicted by a flat organizational chart. Considerations The type of organizational chart that the company draws must be based on the type of trade it is into. It is not practical and feasible for large  companies to have a flat organizational structure and chart. Large companies tend to centralize authority and departmentalize their strategic functions. Likewise, when small companies use the tall organizational structure and chart, they have to deal with greater bureaucracy and middlemen’s salaries. Is Kerry food group a flat or tall organisation? Swot Analysis of Kerry Group Kerry Group, Plc. Category Food Processing Sector Food and Beverages Tagline/ Slogan Brands that deliver USP Its worldwide facilities and unrivalled technical support network guarantees that its highly acclaimed ingredient systems and technologies are available to food processor or foodservice companies in all markets. STP Segment Business segments: Ingredients incorporating Culinary, Flavours and Bio-Science, Consumer Foods, Agribusiness and Dairies Target Group Agribusiness: Food sector, Animal feed sector, Drinks sector Consumer Foods & Dairies Consumers of branded & private labeled food products Positioning Committed to evolving food and developing brands that deliver, time and time again SWOT Analysis Strength 1. Established global processing and technical network with an ingredients portfolio extending to some nine thousand products to food processor and foodservice markets in over 120 different countries 2. Core technological strengths in savory ingredients, sweet ingredients, food coating systems, nutritional systems and specialty protein applications 3. An unrivalled national service to the independent convenience sector, in both the UK and Ireland 4. Close working relationships with retail customers to develop mutually successful, private label business 5. One of the leading consumer brands in Ireland and Europe Weakness 1.Input cost volatility due to raw material pricing being impacted by adverse crop production conditions 2. Limited market share and Pressure from competitive markets 3.Ingredients and Flavours market is highly fragmented Opportunity 1.Growth in demand for convenient ‘ready-to-use’ foods to match modern lifestyles and for fresh natural food products 2.Growing Ingredients and Flavours market 3. Tapping global capability via emerging markets & global customers Threats 1.Food industry supply and demand issues 2.Commodity cost inflationary momentum 3.Impact of foreign exchange fluctuations Competition Competitors 1.Associated British Foods Plc. 2.Greencore Group Plc. 3. Westbury Dairies Limited Pest analysis

Design of a global network using wimax - Free Essay Example

Sample details Pages: 31 Words: 9192 Downloads: 6 Date added: 2017/06/26 Category Statistics Essay Did you like this example? Introduction Previous Work Previous work that is closely related to this project involves experience with similar software simulation tool to the one that is used for the completion of the practical part of the project. OPNET simulator was used for the set up of a small network and its division into subnets. The project was completed as a lab assignment in the City University laboratories. It was divided into two main lab sessions each of them explained as follows. The aim of first lab session was to demonstrate the need for implementation of switches in the design of the local area networks. Two 16-station LANs were designed, using a hub for the first one; two hubs and a switch for the second one. The main task of the second laboratory was to demonstrate the basics of designing a network, taking into consideration the users, services location of hosts. Don’t waste time! Our writers will create an original "Design of a global network using wimax" essay for you Create order Using OPNET software, the concepts of networking were easily implemented and tested against the criteria set for satisfactory performance of the network model. The visual representation of the obtained results was used for a detailed analysis of the complexity of the network and its services provided to the users. 1 Technical Overview of the WiMAX Standard 1.1 Spectrum of the Standard The IEEE 802.16 standard is initially designed to provide a flexible, cost-effective, standards-based last-mile broadband connectivity to fill in the broadband coverage gaps that are not currently served by the wired solutions such as DSL. The advanced versions of the standard are aiming to create new forms of broadband services both with high speed and mobility. The IEEE 802.16 standard envisages the use of a wide range of frequencies from 2 to 66 GHz. However, the WiMAX Forum has focused on the use of 2 to 10GHz as the operating frequencies. A graphical representation of the WiMAX spectrum bands is listed below. It includes a comparison with other wireless standards; as well as indication of the regions using the listed bands. WiMAX is a technology that supports the delivery of last-mile wireless broadband access as an alternative to cable and DSL. WiMAX provides fixed, nomadic, portable and ultimately mobile wireless broadband connectivity without the need for line-of-sight with a base station. The design of a WiMAX network is based on the following major principles: Spectrum: to be deployed in both licensed and unlicensed spectra. Topology: supports different RAN topologies. Interworking: autonomous RAN architecture that enables faultless incorporation and interworking with Wi-Fi, 3GPP and 3GPP2 networks and existing IP core networks (e.g. DSL, cable, 3G) using IP-based interfaces. IP connectivity: supports a mix of IPv4 and IPv6 network interconnects. Mobility management: opportunity to expand the fixed access to mobility and broadband multimedia services delivery. WiMAX has defined two MAC classification profiles -the ATM and the IP. They have also defined two primary PHY system profiles: 25 MHz-wide channel (in the US) in the 10-66 GHz range. 28 MHz-wide channel (in Europe) in the 10-66 GHz range. IEEE 802.16 standard is designed to develop as a set of air interfaces standards for WMAN based on a universal MAC protocol but using the physical layer specifications, which one dependent on the range of use and the related regulations. The IEEE 802.16 working group designed a flexible MAC layer and associated physical layer for 10-66 GHz. It is more important to recognize certain factors that make some frequencies more suitable for use in WiMAX systems, both fixed and mobile [1new]. 1.1.1 Path Loss The first important factor is the operating frequency and path loss, which may arise from three basic factors: Free space path loss (FSL) It is defined by using the following formula (Equation 1): FSL=10log(4DFC)2 (1) D=distance from transmitter; F=frequency; C=speed of light. The path losses increase with the square of the frequency. For example, the path loss at 2 GHz frequency band is about 12 dB higher than the band at 0.5 GHz. This effect may be compensated with the antenna size. The increase in FSL with the square of the frequency requires the cell sizes at higher frequencies to be smaller in order to maintain link margins. High frequencies such as 5.8 GHz and above are best suited for line of sight environment. In NLOS conditions, a link at 5.8 GHz would support NLOS customer premises equipment at distances less than a kilometre. Loss due to NLOS operations In urban environments, WiMAX systems operate in a NLOS manner, there is a loss in received signals which depends on the reflected signal strengths. Frequencies above 10 GHz are treated separately. In general, lower frequencies such as 800-2000 MHz have better performance for NLOS than the higher bands. Due to the reception of waves reflected from many objects, the signal strength in most NLOS conditions varies sharply. Ground propagation models are required for path loss analysis and as a result additional margin needs to be given for the loss expected. Hence, multiple antenna techniques with spatial diversity are used to improve the margins in NLOS conditions. Loss caused by in-building penetration This kind of loss depends largely on the type of wall and whether the indoor location has windows. They are not very frequency dependent, at least in the zone of consideration of 2 GHz to 4 GHz. In buildings, losses can vary from 2 dB for a room with windows; to 6 dB for a brick wall. An increase up to 10-12 dB can be expected if the indoor areas were built using metal materials. 1.1.2 Doppler Shift and Coherence Time The second important factor is the Doppler Shift. It is an essential consideration for systems meant for mobile use. In the case of mobile WiMAX systems, which are meant to cater to vehicular speeds of up to 120 km/h, the effects of the Doppler shift are only relevant to the higher frequencies. It is given by the following formula (Equation 2): Ds=(VFC)cos (2) Ds=Doppler shift; V=velocity of user; F=frequency; C=speed of light and =angle between the incoming signal and direction of motion. Frequency shifts need to be less than 10% of the subcarrier spacing in order to maintain correct timing between different mobile stations, which may be operating with a base station. Table 1 represents the relationships between Doppler shift with operating frequency and speed. Frequency (MHz) Doppler shift (Hz) Coherence time (ms) Symbol duration (ms) 800 88.9 11.3 0.2 1600 177.8 5.6 0.2 2400 266.7 3.8 0.2 3400 377.8 2.6 0.2 5800 644.4 1.6 0.2 10000 1111.1 0.9 0.2 Table 1. Coherence time in ms is relevant to time synchronisation of mobile stations with the base station (times are in milliseconds) WiMAX is a multicarrier transmission system based on OFDM. The uplinks in WiMAX (both FDD and TDD systems) operate in a TDMA mode. Each subscriber station is assigned its own time slot and the transmission must take place within the slot. Other devices have the right to transmit in the other slots as allotted in the frame of WiMAX. In other words, the coherence of timing between different devices is important, which must operate in synchronisation. The coherence time is defined as 1Ds and it is inversely proportional to the Doppler shift. An indicator of how the motion is affecting the connection between symbols from different devices, a comparison of coherence time and the symbol time in OFDM. Hence, rather than considering a shift in the centre frequency, which is more likely for single-carrier systems, it is more suitable to consider the same shift in time in the subcarriers. Reducing subcarrier spacing would have adversely affected the Doppler spread, whereas increasing the subcarrier spacing would have reduced the delay spread and consequently intersymbol interference and the data rate. 1.2 Architecture In addition to the standard spectrum analysis and factors that are important for the appropriate selection of correct frequencies, the next part of the report presents the ideas of WiMAX network architecture and specifications. 1.2.1 Backhaul Solutions In telecommunications, thebackhaulportion of the network comprises the intermediate links between thecore networks, orbackbone, of the network and the small sub networks at the edge of the entire hierarchical network. Based on principle explained above, one of the architecture models is based on fixed IEEE 802.16 equipment. Independent of the used version, the technology can be employed in a fixed infrastructure as shown in Fig. 2. In this setting, the deployment of point-to-point connections can span tens of kilometres. WiMAX backhauling is defined by the infrastructure between the WiMAX ASN-GW and the base stations. [2 new] The control of the wireless network towards the client devices, as well as the transport traffic to the operator CSN is aggregated by the base stations. Fig. 3 is another example of how the system may be structured. A critical achievement factor in the deployment of the WiMAX systems is the numerous options the service provider can choose from. As the variety of options for the service providers were mentioned, there is time to focus on a topic much more related to the economic point of a network system. In particular, how the network will be develop in terms of cost and charges and they are agreed upon. A list of the important factors is presented as follows: Fixed costof providing a network infrastructure. Non-fixed cost of connection to the network- typically paid by the user in the form of connection cost. Cost of increasingthe networks capacity. Users who want to reschedule their transmission during peak times should not be charged for the growth of the networks capacity. Incremental cost of sending an extra packet. This cost should be very small or equal to zero without congestion, in view of the fact that the bandwidth of a broadband network is in general a shared resource. Social costdefined as the extra delay which occurs to other users by the transmission of data. Figure 4 shows the cost flow of a WiMAX network. WiMAXpoint to multipoint WiMAXmesh Clients WiMAX MS/RS or WiMAX mesh BS Clients WiMAX MS/RS or WiMAX mesh BS + Wi-Fi router WiMAXcell layout Cell dimensioning Number of WiMAX mesh BS in a cluster Wi-FiCell layout Number of AP in a single WiMAX cell Wi-Fi technology options Dual interface boards (WiMAX/Wi-Fi) Average subscribers per square mile Data traffic assumptions for Wi-Fi users and WiMAX SS/RS (utility/demand function) High QoS VoIP connections for Wi-Fi users and WiMAX SS Average number of data connections per square mile / month Backhaul capacity planning WiMAX BS to ISP WiMAX mesh to WiMAX main BS Wi-Fi routers to WiMAX BS Radio capacity planning Channel size Modulation type Frequency reuse FCC limitations Economic considerations CAPEX: WiMAX BS, Wi-Fi routers, spectrum costs, site preparation, site installation, backbone network equipment OPEX: Operation-administration-management costs, site Leases, equipment maintenance, customer acquisition Network revenue pricing model Time unit fees for Internet subscribers and VoIP subscribers (flat rate pricing) On-demand Service (user-based pricing) Charges: access, usage, congestion and QoS Fig. 4 Cost flow diagram for WiMAX networks 1.2.2 Mobile WiMAX Network Solution The second architecture model that is discussed is that of the mobile WiMAX. It is of great interest and use for the simulation project as it explains the principles behind the simulation that has been set. A WiMAX network consists of an ASN in the lowest level and network itself is in fact, quite intuitive. [1 new] An ASN is comprised of a number of BS connected to an access network, where the ASN is connected to the external networks using ASN-GW. The functions of the ASN are represented in Fig. 5 and include a number of BS, access networks, and access gateways. The functions are discussed in details as follows: Establishing of a connection with the MS, including PHY and MAC layer connectivity. Providing handover and roaming services for the MS within the ASN The user should be provided AAA facilities in conjunction with its home network; the ASN is capable of providing proxy AAA services Relay facilities between the ASN and the external networks should also be present Two functional entities are defined in ASN shown in Fig. 6: The base stationconnects to the MS using the WiMAX PHY air interface. The functions of the BS are to maintain the air interface with the MS, providing the DHCP proxy and to maintain its status idle or active. Fig. 6 is an illustration of a typical WiMAX BS. The uplink and downlink traffic scheduling as well as the QoS enforcement are provided by the BS, as the air interface is managed by the BS. The access service network gateway is the second functional entity. The ASN-GW is the point where traffic from all BS is aggregated for interface to external networks. Usually, the ASN-GW is physically a router. Functions such as QoS management, AAA functionalities are also part of the aggregation point responsibilities. ASN-GW may also have control functions over the BS. The alternative architecture embeds those control functions in the BS. Fig. 7 represents the typical ASN functions. If a comparison between WiMAX network architecture and a cellular network model such as GSM was to be done, similarities can easily be identified. The ASN-GW of the WiMAX network serves the functions that are provided by the SGSN; the access network is recognised as BSC in the GSM model, and the air interface is respectively the BST. Further reading and understanding of the GSM model architecture is recommended for the comparison between the two models. Generally, the WiMAX networks are defined to be much more open in building networks and they have greater level of functionalities in its network entities. Three distinct entities comprise a WiMAX network and its application environment: Network access provider entity that operates one or more ASNs. Typically, it is a WiMAX operator that operates ASN in one or more areas. Network service provider provides connectivity and services to NAPs. NSP needs only to connect to other NSPs and expect all services to be delivered through these connections; NSPs provide connectivity to NAPs via CSN. They are also responsible for providing mobility between their own nodes as well as nodes from other NSPs. Application service providers provide services such as HTTP, video streaming, file download, e-mail, etc. Fig. 8 introduces one more entity of the WiMAX network architecture the connectivity service network. The diagram shows that CSNs have AAA servers which are policy functions for QoS. They provide connectivity to external networks such as managed IP networks or the public internet. Policy functions for each device, user and service on the network as well as the security and authentication frameworks are provided by the AAA servers. Authentication at multiple levels is a key feature of the WiMAX network architecture. Additional key features of the mobile WiMAX network architecture include: Both the core and the radio access networks should be based on IP; protocols based on IEEE802.16 and IETF Open interfaces should be defined by fully-defined reference points Support of fixed network, nomadic, or mobile usage with full migration path to mobility A modular network architecture, which can grow based on usage requirements Integration into different types of IP and non-IP networks (for example: ATM, TDM, and others) Network core architecture is not based on support of any particular service, such as voice, data, or video; as a multi-service core network it supports QoS for each service and each connection QoS is based on both policy functions and enforcement The network architecture is relatively flat, which enables a WiMAX service to start with a single ASN; NWG has defined different ASN profiles for this purpose Inter-networking is supported with 3GPP, 3GPP2, Wi-Fi, or wired networks using IETF protocols. 2 WiMAX Layers After the spectrum and network analysis discussions, it is important to look deeper into WiMAX fundamentals. The following chapter has the aim to introduce the two main layers defined in the WiMAX standard, and to explain the related to them topics such as adaptive modulation, QoS, etc. As the WiMAX belongs to the IEEE 802 group, then the bridging or layer-2 concepts should be mentioned. [2] The addressing is based on MAC addresses and the base station is perceived as a bridge. In order to implement all layer 2 functionalities, the device used should be a bridge-not a router. For the identification for nodes addressing is used; as long as the node is recognized by the network, the address is replaced by use of circuits with circuit identifier. The WiMAX physical layer is based on orthogonal frequency division multiplexing. [2new] OFDM is a transmission scheme that enables high-speed data, video, and multimedia communications. It is used by numerous broadband systems DSL, Wi-Fi, DVB-H, MediaFLO and WiMAX. OFDM is an efficient scheme used for high data rate transmission in a non-line-of-sight or multipath radio environment. The MAC layer is based on connection-oriented principle and it is very similar to the ATM transport protocol, which connection uses a context that describes the mapping between the incoming flows and the underlying QoS. A station registers itself to the base station, negotiates the physical layer characteristics and then can communicate bidirectionally. A service flow defines the negotiated QoS for all matching packets (service-specific sub layer). The QoS can be changed dynamically and it supports extremely well data bursts. Everything is negotiated separately for uplink and downlink. 2.1 Physical Layer Details 2.1.1 OFDM Basics OFDM is a multicarrier modulation scheme that is based on the idea of dividing a given high-bit-rate data stream into several parallel lower bit-rate streams. Each of those streams is then modulated on separate carriers, the so called subcarriers or tones. Multicarrier modulation schemes eliminate or minimize ISI by making the symbol time large enough so that the channel induced delays are an insignificant proportion of the symbol duration. For that reason, in high-data-rate systems, in which the symbol duration is relatively small and it is inversely proportional to the data rate, splitting the data stream into many parallel streams increases the symbol duration of each stream. By doing so, the delay spread is only a small fraction of the symbol duration. OFDM is a spectrally efficient version of multicarrier modulation, in which the subscribers are selected in such way that they are orthogonal to one another over the symbol duration. In that way, it avoids the necessity to have no overlapping subcarrier channels to eliminate ISI. The first subcarrier has to have a frequency such that it has an integer number of cycles in a symbol period. The spacing between adjacent subcarriers (subscriber bandwidth Bsc) has to be defined by the following Equation 3: Bsc=BL (3) Where B is the nominal bandwidth, it is also equal to the data rate. L is the number of subcarriers. This relation ensures that all tones are orthogonal to one another over the symbol period. It can be shown that the OFDM signal is equivalent to the inverse discrete Fourier transform of the data sequence block taken L at a time. Therefore, it is very straightforward to implement OFDM transmitters and receivers in discrete time using IFFT and FFT, respectively. In order to completely eliminate the ISI, OFDM introduces guard intervals between the symbols. For the successful elimination, the guard interval should be larger than the expected multipath delay spread. On the other hand, the introduction of the guard interval implies power wastage and decrease in bandwidth efficiency. The amount of power waste depends on the proportion between the OFDM symbol duration and the guard time. Thus, the larger the symbol period, the smaller the power loss and bandwidth efficiency. Large symbol periods also mean more subcarriers. The size of the FFT in an OFDM design should be chosen carefully as a balance between protection against multipath, Doppler shift, and design cost/complexity. For a given bandwidth, selecting a large FFT size would reduce the subcarrier spacing and increase the symbol time. This is the reason why it makes it easier to protect against multipath delay spread. In contrary, the reduced subcarrier spacing makes the system more vulnerable to intercarrier interference owing to Doppler spread in mobile applications. Careful balancing is required to compete the influence of delay and Doppler spread. 2.1.2 Advantages and Disadvantages of OFDM There are several advantages of OFDM over other solutions for high-speed transmission. Reduced computational complexity: OFDM can be easily implemented using FFT/IFFT, where the processing requirements grow only slightly faster than linearly with data rate or bandwidth. The computational complexity of OFDM can be represented the following Equation 4. O(BlogBTm) (4) Where B is the bandwidth and Tm is the delay spread. This complexity is much lower than that of standard equalizer-based system, which complexity is shown by Equation 5: O(B2Tm) (5) Graceful degradation of performance under excess delay: the performance of an OFDM system degrades gracefully as the delay spread exceeds the value designed for. Greater coding and low constellation sizes can be used to provide fallback rates that are significantly more robust against delay spread. In other words, OFDM is well suited for adaptive modulation and coding, which allows the system to make the best of the available channel conditions. This is in contrast with the abrupt degradation owing to error propagation that single-carrier systems experience as the delay spread exceeds the value for which the equalizer is designed. Exploitation of frequency diversity : OFDM facilitates coding and interleaving across subcarriers in the frequency domain, which can provide robustness against burst errors caused by portions of the transmitted spectrum undergoing deep fades. WiMAX defines subcarrier permutations that allow systems to exploit this. Use as a multi-access scheme : OFDM can be used as multi-access scheme, where different tones are partitioned among multiple users. This scheme is also known as OFDMA and is exploited in mobile WiMAX. The ability to provide fine granularity in channel allocation is also offered by the OFDMA. In relatively slow time-varying channels, it is possible to significantly enhance the capacity by adapting the data rate per subscriber according to the SNR of that particular subcarrier. Robust against narrowband interference Suitable for coherent demodulation : it is relatively easy to do pilot-based channel estimation in OFDM system, which renders them suitable for coherent demodulation schemes that are more power efficient. Apart from the advantages that were already described, there are two main disadvantages: There is a problem associated with OFDM signals having a high peak-to-average ratio that causes nonlinearities and clipping distortion. This can lead to power inefficiencies that need to be countered. The second disadvantage is related to OFDM signals which are very susceptible to phase noise and frequency dispersion, and the design must mitigate these imperfections. This also makes it critical to have accurate frequency synchronization. 2.1.3 OFDMA: Sub channelization Sub channels are formed by the division of available subcarriers into groups. [3new] Fixed WiMAX based on the OFDM-PHY allows a limited form of sub channelization in the uplink only. There are 16 defined sub channels, where 1,2,4,8 or all sets can be assigned to a subscriber station in the uplink. Uplink sub channelization in fixed WiMAX allows SSs to transmit using only a fraction (as low as 1/16) of the bandwidth allocated to it by the BS. The scheme used allows link budget improvements and can be used to improve range performance and/or improve battery life of SSs. A typical 1/16 sub channelization factor provides a 12 dB link budget enhancement. In contrast, mobile WiMAX uses OFDMA-PHY and it allows sub channelization in both the uplink and downlink. Sub channels effectively form the minimum frequency resource-unit, which is allocated by the BS. Therefore, different users may be allocated different sub channels as this is multiple-access mechanism. It is also known as orthogonal frequency division multiple access, which gives mobile WiMAX PHY its name. Sub channels may be formed using wither contiguous subcarriers or subcarriers pseudo-randomly distributed across the frequency spectrum. More frequency diversity is achieved by using distributed sub carriers, which is particularly useful for mobile applications. WiMAX defines several sub channelization schemes based on distributed carriers for both the uplink and downlink. One of them is partial usage of subcarriers, which is mandatory for all mobile WiMAX implementations. The second sub channelization scheme is based on contiguous subcarriers and is also known as adaptive modulation and coding. Although the frequency diversity is lost, band AMC allows system designers to exploit multiuser diversity, allocating sub channels to users based on their frequency response. Multiuser diversity can provide significant gains in overall system capacity, if the system strives to provide each user with a sub channel that maximizes its received SINR. Generally, the contiguous sub channels are more suited for fixed and low-mobility applications. Fig. 9 shows a typical sub carrier structure. FIGURE 9 + explanation 2.1.4 Frame Structure Mobile WiMAX used to support Time Division Duplex only but recently full and half-duplex Frequency Division Duplex support has been added. [4 new] It is mainly because of local restrictions in some areas. A major disadvantage of the TDD is that it needs to be synchronised over the whole system. On the other hand, there are several reasons why TDD usage is preferred. One of them is that the ratio of DL/UL data rates can be adjusted freely. It is in contrast with the FDD where the ratio is always constant and in most cases symmetric. Channel reciprocity is assured by using TDD, which gives better support of link adaptation, MIMO and other closed loop advanced antenna technologies. Whereas FDD requires a pair channel, but TDD can share one for both DL/UL traffic. Additionally, from economical point of view, FDD transceivers are more complex and therefore more expensive to manufacture. For the simulation project that has been set up, FDD mode was used and for this purpose the next part of this chapter explains the FDD frame structure in relation to relaying. For information purposes TDD frame structure is also discussed. 2.1.4.1 Frame Format for FDD The FDD mode does not provide guard times and parallel transmissions in DL and UL. [5new] The BS always sets up the master frame, in other words, it generates the timing schedule for the next period. The process begins with synchronisation pilots, a broadcast channel and a random/contention access channel; a few regular frames follow, but this very much depends on the technology used. Some of the frames are reserved for the second hop(s) by the BS, which are later used in the responsibility of the relay(s). A term called stealth relaying is used when the BS does not even distinguish between relays and ordinary SSs. It is preferable to use centrally and relay-aware BS controlled resource allocation for further systems. Interleaved multihop frames are incorporated by modern multihop systems, where frames for the first and second hops alternate in time and they are all controlled by the BS. The smallest granularity resource unit is a chunk, 100 chunks form a basic frame. Symbols, on the other hand, are used for signalling and synchronization, but they are out of focus here. They are shown in grey in Fig. 10(a) and the only impact here is the overhead-resources not available for data throughput. DL and UL transmissions happen simultaneously in the same frame raster. There are 3 ways of integrating relaying (the frames used for the second hop or beyond: Time Domain Relaying: resources for hop1 and hop2 are separated in time (sequentially) Frequency Domain Relaying: recourses for hop1 and hop2 are separated in frequency (neighbour band) OFDMA Domain Relaying: recourses for hop1 and hop2 are separated in frequency (sub channels) As OFDMA was already introduces as topic earlier, it is important to describe what its advantages are over OFDM relaying. First one is that the resources can be subdivided in a finer granularity than it is possible using OFDM only. Fig. 10(b) shows that first-hop transmissions are always treated the same way. They only occupy the required resources for their traffic and there is not waste due to completely assigned but incompletely filled frames. In the UL several SSs share the full bandwidth and each of them transmits on a subset of sub channels, with a guard band between them. The BS or RN coordinates the orthogonal interference-free use of these sub channels by the SSs. OFDMA subdivision in the DL is also available, where the BS and RN send on distinct sub channels, but using sufficient guard band. Even if the side band power is below the signal level, this can cause serious interference trouble at the SS when receiving the useful signal from a far dist ant BS and the interference from the RN nearby. In this case, interference mitigation strategies in the BS are helpful. This also leads to proper association decisions for intra-cell handover. The handover concept is introduced later in the report and the fundamental principles are discussed in details. 2.1.4.2 TDD Frame Structure Mobile WiMAX TDD mode allows the DL and UL transmissions to share the same transmission medium. [6new] Fig. 11 shows the typical structure of TDD frame. Transmission and reception cannot occur simultaneously, due to the prohibitively complex filtering, which is essential for the separation of UL and DL. Something more, in order to avoid interference between the signals transmitted from the BS and other SSs, time gaps such as the transmit/receive transition gap or receive/transmit transition gap are needed. The TTG allows sufficient time for the BS to switch from transmit to receive mode. RTG provides time for the BS to switch from receiving to transmitting. Parameters that form the size of the time gaps are: cell radius, the transceiver turnaround time and other implementation constraints. 2.1.5 Adaptive Modulation and Coding in WiMAX It is inevitable to mention the modulation and coding techniques that are employed by the WiMAX standard. Their principles are important as later in the report; those modulations are used for the simulation purposes and are base on the discussion how the SSs can be connected to the BSs and what effect the modulation and coding have on the connectivity. WiMAX supports a variety of modulation and coding schemes. [3 new]This allows the scheme to change on a burst-by-burst basis per link, depending on channel conditions. The SS can provide feedback on the DL channel quality to the BS by using channel quality feedback indicator. For the UL, the BS can easily estimate the channel quality, based on the received signal quality. The BS scheduler can take into account the channel quality for each users UL and DL and assign a modulation and coding technique that maximizes the throughput for the available SNR. Adaptive modulation and coding increases the overall system capacity, as it allows real-time trade-off between throughput and robustness on each link. Table 2 lists various modulation and coding scheme used by WiMAX. In the DL, QPSK, 16 QAM, and 64 QAM are mandatory for both fixed and mobile WiMAX. 64 QAM is optional in the UL. FEC coding using conventional codes is mandatory as well. Conventional codes are combined with an outer Reed-Solomon code in the downlink for OFDM-PHY. Turbo codes and low-density parity check codes are optionally supported at a variety of code rates as well. There are 52 combinations of modulation and coding techniques that are defined in WiMAX as burst profiles. Downlink Uplink Modulation BPSK, QPSK, 16 QAM, 64 QAM; BPSK optional for OFDMA-PHY BPSK, QPSK, 16 QAM; 64 QAM optional Coding Mandatory: convolution codes at rate , 2/3, , 5/6 Mandatory: convolution codes at rate , 2/3, , 5/6 Optional: convolution turbo codes at rate , 2/3, , 5/6; repetition codes at rate ,1/3, 1/6, LDPC, RS-Codes for OFDM-PHY Optional: convolution turbo codes at rate 1/2., 2/3, , 5/6; repetition codes at rate , 1/3, 1/6, LDPC Table 2. Modulation and Coding supported by WiMAX. 2.2 MAC Layer Details The second important layer of the WiMAX standard is the MAC medium access control. In general, the 802.16 MAC is designed to support multipoint-to-multipoint architecture, where a centrally located BS handles multiple independent sectors simultaneously. [7 new] On the downlink, data to SSs are multiplexed in TDM fashion. On the contrary, the uplink is shared between SSs in TDMA fashion. IEEE standard 802.16 defines 2 general service-specific convergence sub-layers for mapping services to and from 802.16 MAC connections. The first one is the ATM convergence sub-layer, which is defined for ATM services. The second one is the packet convergence layer, defined for mapping packet services such as IPv4, IPv6, Ethernet, and virtual local area network. There are 3 primary tasks of the sub-layer: To classify service data units to the correct MAC connection Preserve or enable QoS Enable bandwidth allocation Depending on the type of service, the mapping takes a range of forms. Additionally to the basic convergence sub-layer tasks, the layers can also perform more complicated functions payload header suppression and reconstruction to enhance air link efficiency. As it was already mentioned, the 802.16 MAC is connection-oriented and all services, including inherently connectionless services, are mapped to a connection. Thus, it provides a mechanism for requesting bandwidth, associating QoS and traffic parameters, transporting and routing data to the appropriate convergence sub-layer; as well as all other actions associated with the contractual terms of service. Connections are referenced with 16-bit connection identifiers and may require continuously granted bandwidth or bandwidth on demand. Every SS has a standard 48-bit MAC address, which serves mainly as an equipment identifier. The primary addresses used during operation are the CIDs. Three management connections are assigned to the SS when entered the network. These connections reflect the three different management connections in each direction: Basic connection- used for the transfer of short, time-critical MAC and radio link control massages. Primary management connection- used to transfer short longer, more delay-tolerated messages (e.g. those used for authentication and connection setup). Secondary management connection- used for the transfer of standards-based management messages, such as DHCP, TFTP, and SNMP. Apart from the management connections, transport connections for the contracted services are also allocated to the SSs. Transport connections are unidirectional and facilitate different DL and UL QoS and traffic parameters; they are typically assigned to services in pairs. Additional connections for other purposes may also be reserved by MAC: Contention-based initial access Broadcast transmissions in the DL, as well as for signalling broadcast connection-based polling of SS bandwidth needs Multicast, rather than broadcast, connection-based polling. SSs may be instructed to join multicast polling groups associated with these multicast polling connections. 2.2.1 MAC PDU Construction and Transmission As it was already discussed, the MAC sub-layer is independent of the higher-layer protocol and performs such operations as scheduling, [3 new] ARQ, bandwidth allocations, modulation and code rate selection. The SDUs arriving from the higher-layer to the sub-layer are assembled to create the MAC PDU, which is the basic payload unit handled by the MAC and PHY layers. Multiple SDUs can be carried on a single MAC PDU, or a single SDU can be fragmented to be carried over multiple MAC PDUs; this is entirely based on the size of the payload. When an SDU is fragmented, the position of each fragment within the SDU is labelled by a sequence number. The usage of the sequence number is to ease assembling of the SDU from its fragments in the correct order at the receiver MAC layer. Multiple MAC PDUs destined to the same receiver can be concatenated and carried over a single transmission opportunity or data region. This is purely done to use the PHY resources more efficiently. This is shown in Fig. 12. For non-ARQ-enabled connections, each fragment of the SDU is transmitted in sequence. For ARQ-enabled connections, the SDU is first divided into fixed length ARQ blocks. Each ARQ block has its own block sequence number. ARQ BLOCK-SIZE parameter is used by the BS for each CID to specify the length of the block. The length of the SDU should be integral multiple of the ARQ BLOCK-SIZE, if it is not the last ARQ block is padded. Once the SDU is portioned into ARQ blocks, the partitioning remains until all the ARQ blocks have been received and acknowledged by the receiver. After the partitioning, the SDU is assembled into MAC PDUs in a normal fashion as it is shown in Fig. 12. For ARQ-enabled connections, the fragmentation and packing sub head er contains the BSN of the first ARQ block following the sub header. The ARQ feedback from the receiver comes in the form of ACK indicating successful reception of the ARQ blocks. The feedback is sent either as a stand-alone MAC PDU or piggybacked on the payload of a regular MAC PDU. ARQ feedback can be two types: Selective:indicates that the ARQ block has been received without errors Cumulative:indicates that all blocks with sequence number less than or equal to the BSN have been received without error. Each MAC PDU consists of a header followed by a payload and cyclic redundancy check. The CRC is based on IEEE 802.3 and is calculated on the entire MAC PDU; the header and the payload. Two types of PDUs (Fig. 13) are introduced, and each of them has different header structure: Generic PDU- used to carry data and MAC-layer signalling massages. It starts with a generic header, which structure is shown on Fig.13, and then followed by a payload and a CRC. The different information elements in the header of a generic MAC PDU are shown in Table 3. Bandwidth PDU- used by the SS to inform the BS that more bandwidth is needed in the UL, due to pending data transmission. This type of PDU consists of bandwidth-request header, and there is no payload or CRC. The header information elements are shown in Table 4. Field Length (bits) Description HT 1 Header type (set to 0 for such header) EC 1 Encryption control (0= payload not encrypted; 1= payload encrypted) Type 6 Type ESF 1 Extended sub header field (1 = ES present; 0 = ES not present) CI 1 CRC indicator (1 = CRC included; 0 = CRC not included) EKS 2 Encryption key sequence (index of the traffic encryption key and the initialization vector used to encrypt the payload) Rsv 1 Reserved LEN 11 Length of MAC PDU in bytes, including the header CID 16 Connection identifier on which the payload is to be sent HCS 8 Header check sequence Table 3, Generic MAC header fields Field Length (bits) Description HT 1 Header type (set to 1 for such header) EC 1 Encryption control (set to 0 for such header) Type 3 Type BR 19 bandwidth request (the number of bytes for uplink bandwidth request by the SS for the given CID) CID 16 Connection identifier HCS 8 Header check sequence Table 4. Bandwidth request MAC header fields Once a MAC PDU is constructed, it is handed over to the scheduler, which schedules the MAC PDU over the PHY resources available. The scheduler checks the service flow ID and the CID of the MAC PDU, which allows it to gauge its QoS requirements. Based on the QoS requirements of the MAC PDUs belonging to different CIDs and service flow Ids, the scheduler determines the optimum PHY resource allocation for all the MAC PDUs, on a frame-by-frame basis. 2.2.2 DL and UL MAP WiMAX MAC supports both TDD and FDD modes. [7 new] In FDD, both continuous and burst downlinks are supported. Continuous downlinks allow for certain robustness improvement techniques for example interleaving. Burst downlinks allow the use of more complex robustness and capacity enhancement techniques, e.g. subscriber level adaptive burst profiling and advanced antenna systems. The MAC builds the DL sub frame, starting with a frame control section. The frame control section contains the DL-MAP and UL-MAP messages. They indicate PHY transitions on the downlink; bandwidth allocations and burst profiles on the uplink. The DL-MAP is applicable to the current frame and is always at least 2 FEC blocks long. In both TDD and FDD modes, the UL-MAP provides allocations starting no later than the next downlink frame. If the processing times and the round trip delays are observed, then the UL-MAP may allocate starting in the current frame. The minimum time between receipt and applicability of the UL-Map for an FDD system is shown in Fig. 14 2.2.3 Authentication, Registration and Security Another important factor of the MAC protocol is that it manages procedures such as authentication, registration and security. Each of the SS holds two certificates: factory installed X.509 digital certificate and certificate of manufacturer. Those certificates are sent from the SS to the BS in the Authorization Request and Authentication Information messages. The certificates establish a link between the 48 bit MAC address of the SS and its public RSA key. The network is able to identify the SS using the certificates, and afterwards it can check the authorization of the SS. If the SS is authorized to join the network, BS will respond with an Authorization Reply containing an Authorization Key. The Authorization Key is encrypted with the SSs public key and used to secure further transactions. When the authorization is successful, the SS will be registered with the network. This will establish the secondary management connection of the SS and determine capabilities related to connection setup and MAC operation. The version of IP used on the secondary management connection is also determined during registration. WiMAXs privacy protocol is based on the Privacy Key Management protocol. It is based on the DOCSIS BPI+ specification, but has been modified to fit seamlessly into the MAC protocol. It accommodates stronger cryptographic methods, such as the Advanced Encryption Standard. PKM is build around the concept of security associations. SA is a set of cryptographic methods and the associated keying material. It contains the information about which algorithms to apply, which key to use, and so on. Every SS establishes at least one SA during initialization. Apart from the basic and primary management connections, all other connections are mapped to an SA either at connection setup time or dynamically during operation. For the traffic encryption, the PKM uses the Data Encryption Standard, running in the cipher block chaining more with 56-bit keys. The CBC initialization vector depends on the frame counter and differs from the frame to frame. To reduce the number of computationally intensive public key operations during normal operation, the transmission encryption keys are exchanged using 3DES with a key exchange key derived from the authorization key. The PKM protocol messages are authenticated using the Hashed Message Authentication Code protocol with SHA-1. Message authentication in essential MAC functions, such as the connection setup, is provided by the PKM protocol. 2.2.4 Services and Parameters The last part of the MAC layer is the services and their parameters. It is an essential part of the standard implementation and this part of the chapter lists all QoS that are provided by the WiMAX family. Scheduler is the one that controls the scheduling services for the standard and handles the mechanisms supported by the MAC to transport data. [9 new] Each connection is associated with a single data service. Data services are associated with a set of QoS parameters that define their behaviour. Two data parameters are used for the management of the parameters: dynamics service addition and dynamic service change. Five different services are supported: unsolicited grant services, real-time polling services, extended real-time polling services non-real-time polling services, and best effort. Table 5 lists the application and specification for each of those services. [10 new] QoS Category Applications QoS Specifications UGS VoIP Maximum sustained rate Maximum latency tolerance Jitter tolerance rtPS Streaming audio and video Minimum reserved rate Maximum sustained rate Maximum latency Traffic priority ertPS Voice with activity detection (VoIP) Minimum reserved rate Maximum sustained rate Maximum latency tolerance Jitter tolerance Traffic priority nrtPS File transfer protocol Minimum reserved rate Maximum sustained rate Traffic priority BE Data transfer, web browsing, etc. Maximum sustained rate Traffic priority Table 5. Mobile WiMAX applications and QoS UGS- supports real-time data streams. Each stream is of fixed-size data packets issued at periodic time intervals. It is particularly useful for applications such as VoIP without silence suspension. Mandatory service flow parameters are: maximum sustained rate, maximum latency tolerance, jitter tolerance and request/transmission policy. If the policy is present, the minimum reserved traffic rate parameter will be the same value as the maximum sustained traffic rate parameter. rtPS- supports real-time data streams, each of which is issued at periodic intervals. It is useful for MPEG videos and consists of variable-size data packets. Compulsory parameters are: minimum reserved rate, maximum sustained rate, maximum latency, traffic priority, and again request/traffic policy. ertPS- it is a combination of USG and rtPS. [4new] ertPS is designed to support VoIP with activity detection, which means that when there is a silence period in the communication, the bandwidth can be saved by downsizing the packets length. The maximum sustained traffic rate, which defines the default size of the allocations, may be changed with ertPS. nrtPS- used for delay-tolerant data streams, which consist of variable data packets. Minimum data rate is required as it used the FTP. Flow parameters are: minimum reserved rate, maximum sustained rate, traffic priority, and request/transmission policy. BE is used to support data streams for which no minimum service level is required and therefore may be handled on a space-available basis. Associated parameters are: maximum sustained rate, traffic priority, and request/transmission policy. 3 Handovers The aim of the next chapter is to introduce the term handovers and to explain their importance for the WiMAX standard features. Handovers are very vital part of a wireless technology.[11new] When an SS moves between different BSs, the connection should also move and in order to do so a seamless handover should be performed. By the term seamlessness, it defines the necessity to maintain current session, QoS and service level agreements during and after the handover. In other words, the seamless handover should not be noticeable by the user; however, this very much depends on the kind of services the user is requiring. With real-time applications, such as videoconferencing or streaming media, s slight decrease of the connection may be observed. In contrast, while a user is browsing a website or transfers files, they will most probably not notice any change in their connection. There are two crucial factors related to the handover procedure: the latency and the packet loss. They have to be as small as possible to make the handover seamless. Several reasons why and when a handover should be initiated are listed below: SS current position and velocity high velocity may lead to different handover decisions Link quality in case a BS is overloaded, the network can decide to relocate some of the SSs Conserving battery power for battery saving purposes, an SS may chose to switch to a closer station and be energy efficient Context and requirements if an SS requires different type of service, it may be necessary to change BS. Handovers have a significant effect on the performance of channel allocation algorithms. At high traffic loads, the majority of forced call terminations are as a result of the lack of channels available for handover rather than to interference. This is a major problem in microcellular systems, where the rate of handovers is considerably higher than that in normal cellular systems. There are a number of solutions to reduce the performance penalty caused by handovers. One of them is to reserve some channels solely for handovers, generally referred to as cut-off priority or guard channel schemes. However, this solution reduces the maximum amount of carried traffic or system capacity and hence yields increased new call blocking. Algorithms that give higher priority to requests for handovers than to new calls are called Handover prioritization schemes. Guard channel schemes are therefore a type of handover prioritization arrangement. Another type of handover prioritization is constituted by handover queuing schemes. Normally, when an allocation request for handoff is rejected, the call is forcibly terminated. By allowing handover allocation requests to be queued temporarily, the forced termination probability can be reduced. The simplest handover queuing schemes use a First-In First-Out (FIFO) queuing regime. A non-pre-emptive priority handover queuing scheme in which handover requests in the queue that are the most urgent ones are served first. A further alternative to help reduce the probability of handover failure is to allow allocation requests for new calls to be queued. New call allocation requests can be queued more readily than handovers because they are less sensitive to delay. Handover queuing reduces the forced termination probability owing to handover failures but increase the new call blocking probability. New call queuing reduces the new call blocking probability and also increases the carried teletraffic. This is because the new calls are not immediately blocked but queued, and in most cases they receive an allocation later. Handovers have a significant effect on the performance of channel allocation algorithms. At high traffic loads, the majority of forced call terminations are as a result of the lack of channels available for handover rather than to interference. This is a major problem in microcellular systems, where the rate of handovers is considerably higher than that in normal cellular systems. There are a number of solutions to reduce the performance penalty caused by handovers. One of them is to reserve some channels solely for handovers, generally referred to as cut-off priority or guard channel schemes. However, this solution reduces the maximum amount of carried traffic or system capacity and hence yields increased new call blocking. Algorithms that give higher priority to requests for handovers than to new calls are called Handover prioritization schemes. Guard channel schemes are therefore a type of handover prioritization arrangement. Another type of handover prioritization is constituted by handover queuing schemes. Normally, when an allocation request for handoff is rejected, the call is forcibly terminated. By allowing handover allocation requests to be queued temporarily, the forced termination probability can be reduced. The simplest handover queuing schemes use a First-In First-Out (FIFO) queuing regime. A non-pre-emptive priority handover queuing scheme in which handover requests in the queue that are the most urgent ones are served first. A further alternative to help reduce the probability of handover failure is to allow allocation requests for new calls to be queued. New call allocation requests can be queued more readily than handovers because they are less sensitive to delay. Handover queuing reduces the forced termination probability owing to handover failures but increase the new call blocking probability. New call queuing reduces the new call blocking probability and also increases the carried teletraffic. This is because the new calls are not immediately blocked but queued, and in most cases they receive an allocation later. There are two main types of handovers: horizontal (handovers within the same technology) and vertical (handovers between different network access technologies). Horizontal handovers- are Layer-2 handovers and are also referred to as micro-mobility. In this case only the BS is changed and the IP-information is kept the unchanged. This kind of handover causes small latency and low packet loss Vertical handovers- Layer-3 handovers and are also referred as macro-mobility. It changes the IP-connection point, and as a result the IP information is changed as well. As a result, significant latency and packet loss are observed. 3.1 Handover Types WiMAX specification supports three types of handovers: Hard Handover, Fast Base Station Switching, and Macro Diversity Handover.[4new] HHO is compulsory, whereas the other two are optional. The WiMAX forum has been working on the enhancement of the HHO techniques to achieve handovers in less than 50 milliseconds. 3.1.1 Hard Handover HHO is a procedure that changes the serving BS using a break-before-make approach. Effectively, this means that the connection to the old BS is broken before the new BS is connected to the SS. Using this approach, excess signalling traffic is avoided during the handover procedure, however, the time before the connection is again in normal operation may be longer. While the SS is connected to a BS, it listens to the link-layer messages for another BS, which periodically broadcasts neighbour advertisement messages. The advertising messages are used for network identification and recognition of the services that are provided. Facts about the signal quality from a neighbouring BS are included in the messages. In case a better BS is not found, the SS stores the information that has been received for future handovers. Fig. 15 illustrates a typical scenario of HHO, when a moving user reaches the point where the signal level is of better quality with another BS. A further decision criterion has to be set up to avoid constant handover back and forth between BSs. 3.1.2 Macro Diversity Handover When MDHO is supported by MS and by BS, the Diversity Set (or in some cases it is called Active Set) is maintained by SS and BS. Diversity set is a list of the BSs, which are involved in the handover procedure. Diversity set is defined for each of SSs in network. SS communicates with all BSs in the diversity set (Fig. 16). For downlink in MDHO, two or more BSs transmit data to SS such that diversity combining can be performed at the SS. For uplink in MDHO, MS transmission is received by multiple BSs where selection diversity of the received information is performed. The BS, which can receive communication among SSs and other BSs, but the level of signal strength is not sufficient is noted as Neighbour BS. While the SS is moving towards the neighbouring BS, at some moment the signal from the neighbouring BS becomes strong enough and the BS can be included in the active set. The factor that is used to measure the inclusion/exclusion of the BS is the long term CINR. There are two ways that the SS uses to monitor DL control information and broadcast messages: It listens only to the anchor BS for burst allocation information of other BSs in the active set Listens to all BSs in the active set. By listening to all active set BSs, a DL/UL-MAP message from any BS may include information for other BSs. The MDHO is started when the SS decides to receive/transmit from multiple BSs at the same time. For DL traffic, two or more BSs transmit the data to the SS, which performs diversity combining. For the UL traffic, the traffic generated by the SS is received by all BSs in the active set and selection diversity is then performed. Interestingly, the MDHO requires all BSs to communicate on synchronised basis, because of the frames sent by the BSs at a certain time frame have to be received by the SS within the specific prefix interval. The BSs frame structure have to be synchronised and the frequency assignments to have the same values. Furthermore, the same set of CIDs and MAC/PHY PDUs sent to the SS have to be generated by the BSs. The encryption information and network entry exchanged information have to be shared between the SS and the BSs as well. 3.1.3 Fast Base Station Switching In FBSS, the SS and BS diversity set is maintained similar as in MDHO. SS continuously monitors the base stations in the diversity set and defines an Anchor BS. Anchor BS is only one base station of the diversity set that MS communicates with for all uplink and downlink traffic including management messages (Fig. 17). This is the BS where SS is registered, synchronized, performs ranging and there is monitored downlink channel for control information. The anchor BS can be changed from frame to frame depending on BS selection method, which means each frame can be sent via different BS in diversity set. Generally, the requirements for the FBSS are the same as the ones of MDHO without the demand for the same CIDs and MAC/PHY PDUs.

Essay about Affirmative Action a Permanent Approach

Affirmative Action: a Permanent Approach One of the hottest debates in recent history has been the validity of a Civil Rights policy called affirmative action. The policy proposes â€Å"preferential treatment† to certain groups based on their minority status, giving them an advantage in job employment and some areas of education. The question asked most often is whether it is constitutional to give advantages to certain groups, excluding some, based solely on their race or ethnicity. It is up to our legal system to use â€Å"strict scrutiny,† or consideration from every standpoint, to assess the issue, which is â€Å"a cost-benefit test measuring whether a law that falls (according to the Court itself) squarely within the prohibition of the equal†¦show more content†¦One argument is that affirmative action will reduce the quality of employees, thus harming our economy by employing workers who only get the job because of their ethnicity, not because of skill or qualifications. Libertarian opponent s of affirmative action say that its policies are inconsistent with the liberal individualism since they require giving benefits to individuals based on membership to a group. In past Supreme Court cases, Justices who have decided against affirmative action have done so because they think that it will encourage racial thinking and alienate minorities. As a matter of policy, the degree to which affirmative action does unintentionally encourage racial thinking is of great importance, but it has no constitutional significance. What is brought into constitutional questionability is whether the rights of the white population are being violated by the affirmative action policy. The question that should now be asked is whether the unemployment of whites due to the loss of their employment to minority groups is justified by affirmative action. According to those who support the policy, it will be. 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Affirmative action was born into a time when our country was attempting to provide equality for all and was only intended to be a temporary measure to bring about this equalityRead MoreWhich Country Has Successfully Implemented the Policy of Affirmative Action and Why Did It Succeed?11582 Words   |  47 PagesIMPLEMENTING AFFIRMATIVE ACTION IN NAMIBIA A summarised guide to the Affirmative Action (Employment) Act (Act 29 of 1998) published and distributed by Namibia Institute for Democracy Updated 3rd Edition  © April 2000 All rights reserved Contents by Dr.J.W.F. van Rooyen NAMIBIA INSTITUTE FOR DEMOCRACY Namibia Institute for Democracy 53 Independence Avenue P.O. Box 11956, Windhoek, Namibia Tel: (061) 229117/8 Fax: (061) 229119 E-mail: nid@mweb.com.na http://www/iwwn.com.na/nid Read MoreEssay on The Resistance to Change1410 Words   |  6 Pages and ignoring unintended consequences. First Barrier Through Alex’s actions in the case study, he was under planning. As the beginning of the case study begins, Alex is warned about the potential problems that are occurring at the department, but he chooses to ignore them. Through his discovery of three letters, he begins to notice that there actually are some inconsistencies within the department and decided to take action. As a leader, there are responsibilities that should not be neglected.Read MoreAffirmative Action Research Paper2403 Words   |  10 PagesAffirmative Action University of Phoenix Susan E. Ricard Since the beginning of affirmative action, there has been controversy about the program being an effective tool to eliminate discrimination in education and the workplace. Even though the numbers with affirmative action plans seemed to have improved the percentage of minorities in schools and workplaces, it does not work to mandate that people change. Once the mandates disappear the numbers begin to decrease. In its conception inRead MoreTeen Court Programs Should Be Established1034 Words   |  5 Pagesoffenders because they are given the opportunity to think about their actions and correct their wrongdoings. First-time offenders, teens who do not have a juvenile record, are typically kids who get involved with the wrong crowd and commit crimes such as underage drinking or shoplifting. These special court cases are not a determination of innocence or guilt, but a way of determining the appropriate reformative course of action for the defendant. Typical teen court sentencing options include communityRead More Managing Diversity Essay1812 Words   |  8 PagesDifferences that replenish energy and undermine productivity and performance in an organization extend to issues like personality styles (Gordon, 2000). Diversity management contains three (3) components: 1. Equal Employment Opportunity/Affirmative Action programs direct attention to laws that guide recruitment and promotion. 2. Valuing differences centers on interpersonal qualities that shape management’s relationships with their employees. 3. Managing diversity focuses on the diverse qualityRead MoreManaging Diversity1891 Words   |  8 PagesDifferences that replenish energy and undermine productivity and performance in an organization extend to issues like personality styles (Gordon, 2000). Diversity management contains three (3) components: 1. Equal Employment Opportunity/Affirmative Action programs direct attention to laws that guide recruitment and promotion. 2. Valuing differences centers on interpersonal qualities that shape management s relationships with their employees. 3. Managing diversity focuses on the diverse qualityRead MoreConflict Of The Case Of Online Defamation1299 Words   |  6 Pagesapply to the case at hand. There appear to be three stages involved: (a) the inquiry whether there is a conflict of policy, (b) the inquiry whether there is a conflict in application, and, (c) if the answer to the previous two questions is in the affirmative, the resolution of the resulting conflict. In the normal case, where the facts and events that are said to constitute the tort have all occurred in one country, there is no difficulty in deciding where the said wrong was committed. But a moreRead MoreAnalyzing Diversity Within The Workplace1061 Words   |  5 Pagesare different from one another whether it be ethnicity, religious beliefs, cultural differences, sexual orientation or gender identification, etc. This paper will analyze both the benefits and problems of a diversified workplace. Keywords: Affirmative Action; Diversity; Diversity Management; Diversity Training; Equal Employment Opportunity (EEO) Literature Review The understanding of race, class, and gender as well as systematic racism and chauvinism must be understood before any analysis of theRead MoreDeveloping Efficient Framework For Social Security Data Mining1606 Words   |  7 Pagesinfo to discriminate the requirement for a bias toward security. These measurements ar accustomed infer the state of the facility system that are classified as either â€Å"stressed† or â€Å"safe.† The system is found to be stressed if the right course of action is to enable the choice theme. Previous studies on PMU measurement-based on-line DSA implicitly suppose that wide space observance systems (WAMS) provide reliable measurements. However, in on-line DSA, PMU measurements will become unprocurable owing

Copyright Law And Its Effects On The World Of Art

Everyday new works of art are being created and are changing the world of art in new and exciting ways. Art being â€Å"something that is created with imagination and skill and that is beautiful or that expresses important ideas or feelings.† (A) Some of these works of art are music, videos, books, movies, pictures and so much more. Many of these creations are innovative and the owners would like to somehow keep their work protected as best they can. This is where Copyright Law is introduced to help protect their property. If another person or entity uses their work the owner would like to have rules and regulations to make sure that use is legal and not damaging to their work. Copyright Law is what protects these creations and allows the†¦show more content†¦50 years later the British Parliament enacted the Statute of Anne in 1710, which put a limit on how long someone’s printed work could be exclusively protected. That limit was 14 years and if still alive th e author could renew the term (C) In todays 21st century society an author’s copyrighted work is protected for the author’s life plus 70 years. (D) Copyright has been around for a very long time and has impacted the way owners protect their work and how exclusive an owner’s work is. Fast-forwarding to 1909, U.S Congress enacted the Copyright Act of 1909 and even further to 1976; U.S Congress amended the act of 1909 and named it the Copyright Act of 1976. Under Title 17 of the United States code Copyright Law exist and thanks to both the acts of 1909 and 1976 Section 1 provides us with this following paraphrased information: 1. Any person entitled thereto, upon complying with the provisions of this title shall have the exclusive right: a) to print, reprint, publish, copy and vend the copyrighted work; b) to translate the copyrighted work into other languages or make it dramatic if nondramatic, or to convert into a novel etc.; c,de) to deliver, read, or present the copyrighted work in public for a profit; f) to reproduce and distribute to public by sale or other transfer of ownership: Provided that the exclusive right

Presentor notes for Conceptual Nursing Models free essay sample

Slide 1 – This is Sister Calista Roy. Sister Roy’s Adaptation Model, referred to as RAM, was developed in 1960, but she continued to expand her conceptual model through the years. In the following slides, we will visit some of the main components of Sister Roy’s Adaptation Model of Nursing Concept. We have discussed the many different conceptual nursing models that affect the way we approach how we treat our patients. As a group, we selected Roy’s Adaptation Model (RAM) because it is the model we all most identify with. When assessing the various conceptual models, we found that RAM, when utilized used as an assessment tool, is an excellent concept in how to address or patients as whole individuals as opposed to just an illness or diagnosis. It helps nurses to consider all of the factors that may be affecting the patient, whether they are contributing to the loss of health or being capable in assisting to regain health. In the following slides, we will show how to utilize RAM in assessing the patient, identifying nursing diagnoses and factors affecting the patient’s health, and creating nursing care plans and appropriate goals based on this information. Ultimately, the goal is for us as nurses to identify what’s wrong and how we can effectively assist the patient in making changes to fix it. The RAM helps to encompass all of the factors affecting this process, not just the physical ones. Slide 2 The RAM conceptual model recognizes the individual as having bio-psychosocial components that affect their health. The nurse encourages and aides in assisting adaptation to these individual components by modifying external stimuli. The 4 ways a person adapts according to the RAM are: 1. Physiological – The basic physical needs required for survival. (E. g. food, water, oxygen, etc. ). 2. Self-Concept – This is how a person sees themselves or how they perceive themselves in the presence of other people in their environment. 3. Role Function – This refers to how a person socially interacts with other people and their need for social integrity. This can be seen in their roles and responsibilities in their life such as being a parent, a professional, or a friend. 4. Interdependence – This refers to how a person interacts with others to get help, affection and attention. Slide 3 These components help nurses to consider the different facets of each individual so that the patient may viewed as a multi-dimensional being, with all of the different perspectives of what affects each person taken into consideration as part of the nursing assessment. For example, first, what basic and immediate physical needs need to be tended to? Secondly, how does the patient’s self-concept affect their overall state? Thirdly, how do the patient’s roles in their life affect their ability for self-care? And finally, how does that patient go about getting what they need to be well? Are they able to ask for help? Are their methods for getting attention effective or self-destructive? These are examples of question nurses ask themselves as consideration for all of the factors affecting their patient’s total state of well-being. Slide 4 The RAM incorporates the four metaparadigm concepts of nursing, which are: person, health, environment, and nursing. The first metaparadigm of nursing addresses the person. The person is not just someone in the bed sick at the hospital. Nursing is concerned with them as a person in context to whatever environment they are in. The person can be sick or well. They may be considered as an individual or as part of a family or community. RAM relates because Roy considered that a person may have an individual self-concept, but they also perceive themselves in relation to others in their environment whether that be their family, employer, community, etc. The second metaparadigm, health is relative. A person may have terminal cancer, but they view their quality of life as good and feel healthy because their current treatments are relieving symptoms for now and their daily life remains relatively intact. Likewise, a person can be physically healthy but emotionally and psychologically unhealthy. RAM addresses health similarly. In RAM, a person is a bio-psychosocial being. The nurse is considering the whole person and their perception of themselves in their whole environment. Health in this area is also relative because the patient’s perception is taken into consideration. Slide 5 The third metaparadigm regarding environment, the nurse considers not just the immediate physical environment such as the hospital bed or clinic, but also whatever environment the patient is in. This could encompass both literal and figurative versions of their home life for example. All the internal and external influences that affect that person are considered as being a part of the environment in which they live. An example might be that while a person’s physical home is shabby, run down and without modern utilities and ample amounts of heat or food, their family is strong, supportive, loving and completely functional within their limitations. An alternate example would be a home that is affixed with all of the modern amenities, clean, warm and stocked with food, water and anything a child could ask for. However, if a child lives in this seemingly perfect home, but a loving, supportive and caring parent is either never present or if there is dysfunction in the family dynamics such as alcoholism or abuse, this impacts the environment as a whole. The RAM considers that the patient is affected by his or her environment and helps the nurse focus on how to assist them in adapting for a positive outcome. Finally, the fourth metaparadigm is that of nursing. Nurses care for individuals as well as communities, the sick and the healthy, by promoting overall health. Nurse may act as a care provider by tending to immediate physical needs of by taking the time to listen or advocate for the patient when they cannot for themselves. The nurse adapts according to what the patient needs to be well. RAM relates here as well because the role of the nurse changes according to what the person needs to adapt in order to achieve their health goals and an overall improved state of health. Slide 6 – There are 3 specific ways RAM can be used to improve nursing practice: formulate as assessment tool, use said tool to form nursing diagnoses, and to set goals. In slide #6, we discuss the assessment tool. To use RAM as the basis of an assessment tool, the nurse would use the four adaption modes of physiological, self-concept, role function and interdependence to gather pertinent data about the patient. For the physiological mode, the nurse would assess all that has to do with the physical body. Fundamental physical assessments such as vital signs, heart, lung and bowel sounds, skin condition such as turgor, color, tenting, neurovascular assessment including circulation, movement and sensation, intake and output patterns with nutrition and fluid status considerations are all examples of data obtained as part of the physiological mode of assessment. For the self-concept mode, the nurse would assess how a patient views themselves and in relation to others. An example of this would be a 60yr old female patient with colon cancer who might be feeling depressed and self-conscious about the colostomy she will need to save her life. For the role performance mode, the nurse would assess what effect the illness might have on the patient’s life in terms of their roles and responsibilities as they view them. For example, a father might be worried that he will not be able to provide for his family financially. Or, perhaps a woman who owns a family business may be concerned that the burden of operating the business while also caring for her children is resting solely on her spouse while she is ill and unable to assist with the daily duties. In the interdependence mode, the nurse would assess the patient’s support system. For example, an elderly woman who lives alone and has poor eyesight might be worried that her family will not have the time to assist her at home with her medications or be too proud to ask for help to the restroom when she needs assistance. Slide 7 – A secondary assessment is used to determine what stimuli are affecting the adaptive or lack of adaptive behavior. Stimuli affecting the patient’s response can be focal, contextual or residual. Here is a patient example where we can look and the different stimuli: A 50yr old man who presents with an exacerbation of COPD. Upon discussion and physical assessment, the nurse finds that the patient has a large amount of stress at home, mostly due to his chronic illness and continues to smoke despite his lung condition. He is only moderately compliant at best with his recommended medication regimen as prescribed by his doctor and admits he doesn’t know how to properly use his inhaler. A focused pulmonary assessment sounds reveal tight airways with moderate secretions and bilateral wheezing and lower lobe rhonchi. These finding are broken up into different types of stimuli as follows: Focal- Sputum and narrowed airways in a patient whose lung sounds reveal wheezing and rhonchi. Contextual- Patient history of COPD while having poor knowledge of how to self-manage the disease. Residual- The patient with COPD who continues to smoke to deal with stress in his/her family life. An effective assessment tool is needed to collect and document data on our patients so what we can identify abnormalities and monitor for changes. The assessment tool helps with the continuity of care so that the next nurse knows the patient’s baseline status as he or she performs their own assessment. Slide 8 – To use RAM as a tool to form a nursing diagnosis, the nurse collects data from all of the four modes and makes a statement (or nursing diagnosis) about the primary and secondary assessments as well as the stimuli thought to cause influence them. An example of appropriate nursing diagnosis based on the COPD patient’s assessment would be: Ineffective Airway Clearance due to excessive secretions. Being able to make a statement or nursing diagnosis about the data collected in the assessments performed as well as their possible contributing factors enables the nurse to identify areas that need attention in order to help the patient adapt in a more effective fashion. Slide 9 – By using the assessment data already collected, the nurse can easily set a nursing care plan and set appropriate patient goals based on the nursing diagnosis for areas that need improvement. For example, the gentleman with an exacerbation with COPD might have the following goals: Patient will maintain a patent airway and breath sounds clear, patient will demonstrate adequate airway clearance and will use effective methods of coughing, and patient will consider smoking cessation. Slides 10 11 – These are example of studies released or published that discuss that actual application of the RAM to the nursing process. In the study regarding menopausal women, the RAM was especially effective in that it addressed the psychological as well as the physical changes these women were experiencing. In the study in the International Journal of Nursing Education, Kaur, H. Mahal, R. (2012), they discussed the RAM as helping nurses to collect and organize information on their patient in a fashion that focuses on the meaningful data. This helps the nurse to identify those areas that need improvement and appropriately plan their care, goals and predictable outcomes around them. While some of the RAM concepts have seemed too abstract, as humans we are all aware of how some of these abstract concepts affect our daily lives, and are thus more than capable as empathetic beings, to adequately address these issues. Approaching patient care in a holistic fashion that addresses the whole patient allows for a more thorough assessment and meaningful approach to intervention and care.

Mrs. Miyagi free essay sample

My name is Paige. I live in an average town, I attend an average school, and in a lot of ways I am just an average senior just waiting to walk across that coveted stage and receive my well-deserved high school diploma. Looking back on these past seventeen years I can say that I have no regrets, although some of the choices I made have affected me in a negative way they have also molded me into the person I am today. The choices that have affected me the most are not what shoes I wore to school that day, but the people I chose to surround myself with. Some of these people were good while others were bad, but there is one individual who has affected me the most and I know that I will never forget Mrs. Haworth. The first day of my junior year I was not excited when I looked at my schedule and read â€Å"Biology II-Robin Haworth, Room 301†. I had never liked biology, I found it boring and the work tedious, I went to the counselor and protested but the chemistry class I wanted was full and I was stuck in biology land learning about niches and ecosystems. As I walked through the door I entered a dark room, with yellow lighting, and smelled disgustingly similar to tuna and popcorn. I took the last seat in the very back of the room and spotted my new science teacher. She had long brown hair, a long hallow face, and two devious eyes that glared at you from behind thin wire framed glasses. The bell rang and the rest of my classmates took their seats and Mrs. Haworth began to tell us how her class was going to be challenging and that if we weren’t up to the challenge she would gladly let us leave. The class was very challenging, and required a lot of outside attention. This was very difficult because I was juggling a new school, a new family, and a new job. My grades soon began to slip and just as I began to drown in a sea of zero’s Mrs. Haworth pulled me to safety and asked me about my life. I told her I was having a difficulty juggling my home life with school while working a part time job. She listened to me and I knew that she genuinely cared about my life and my well-being. After I told her about my basic problems she told me that she understood where I was coming from but I needed to learn how to manage my time better. Mrs. Haworth was no longer my lanky science teacher but my elder and somebody I could go to for guidance. My witty science teacher soon became my own Mr. Miyagi, pushing me to the extreme and letting me solve my own problems. If I made a C on a test she would hand it back and tell me to fix the ones I missed and tell her why I missed them. She neve r increased my grades but taught me how to study harder and that if I gave my all the first time I wouldn’t have any mistakes to fix. Mrs. Haworth never stopped pushing me, she knew I could do better and expected the best. And after many trials and even more errors my grade got better, but I was still having problems at home and I had no one to turn to or lean on. I had never shared my story with someone before but I knew that I could trust Mrs. Haworth and that she would not judge me on my past mistakes or how I was raised. I told her about my absent father and my mother who was never home. I told her about how I got caught up in the wrong crowd at my old school. I told her that I felt like the black sheep of my family and that I felt lost, lonely, and depressed. I told her how I wanted to do more with my life but everyone around me just wanted me to be average. I told her everything and she listened, and began to tell me her story. My teacher and myself have very similar stories, she also had two absent parents and that her only support group was her grandmother. She told me that her sister got caught up in the wrong crowd but she learned from her mistakes and decided that that wasn’t the life she wanted to live. She told me how in high school she never fit in because she cared more about learning and being the best she could be instead of partying on the weekend. She told me how she never listened to what others said and stayed on her own path and how she is happy and wouldn’t change anything. She told me that the mistakes I made in the past do not define me, but the lessons I learned from them did. I had never had an adult open up to me before and treat me as her equal. I still respected Mrs. Haworth but it was not because she was just my teacher but because I knew she had a hard life and worked her hardest so her kids wouldn’t go through the same thing. Mrs. Haworth never let anything stop her from doing what she wanted to do and in fact even exceeded her own expectations. Over the past year she has taught me something that no one else could and that is if I want to be extraordinary I am the only one who could make that happen. I might not be the smartest, funniest, or prettiest individual but I refuse to be average. I know that I am going to walk across that coveted stage and receive my diploma knowing that I did my best and begin my life with my own goals and dreams, and not what others expect from me. Mrs. Haworth taught me to make the most out of my life and she is a living example of how it is possible to come from nothing and be the best. I learned that does not matter what others expect of me but what I expect from myself and to never stop until I achieve it. Robin Haworth is not only my mentor and teacher, but also my friend and her words will be with me wherever I go.