Strategic Purchasing free essay sample

Sustainable business growth and practices are taking a forward leap in to the globe. Almost every business now is planning to have a value chain through out their business. Strategic Purchasing is the key element to a sustainable growth of the business along the competitive edge. This study shows the importance of the Kraljic portfolio model that is to be put in to the actual usage, which would yield benefits of purchasing sophistication in terms of positioning and professionalism. Results showed that both positioning and professionalism are positively related to the greater usage of the model. Based on the analysis of a Dutch chemical company, the immense use of the portfolio model has been described and explored in strategic purchasing. The results have proved that when the model is tailored and elaborated it brings about an effective guidance in purchasing and supplier strategies. The case study also lists out the supplier strategies that are feasible. We will write a custom essay sample on Strategic Purchasing or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Thus it supports the fact by using the kraljic model that purchasing function does play a vital role and enable organizations to gain competitive advantage The Initial objective of strategic purchasing to procure materials amp; equipment’s, from the right origin, with the right quantity and of the right quality, through right time and cost (peter 1993). Strategic purchasing does play a vital role in an organization. To have a successful business venture purchasing has to be the core element responsible for a product’s quality, acceptability, price and reliability. Procurement system solely depends on the choice of suppliers, to ensure the delivery under any circumstances (John, Marton 2006). In few cases, DSM is locked in the partnering relationship due to necessity, might be cause of situations like monopolistic market. The only solution to this would be finding alternative suppliers through proper new development of suppliers. This solution will not be obtainable when the scenario is due to patents, another situation would be when the supplier does not want to involve really in co – development (Van Weele 2006). There is more likely for the partnership to change into the indolent and chances of being more relaxed in the relationship. Strategic partners should always be a supplier of world class. World-class suppliers are high performing, alert at all times and technically sound through sense of economy. This clearly depicts that strategic patterns will meet the benchmark externally with more satisfactory performance of price (Van Weele 2006). Decomplexing strategy and supplier development (2) must be pursed when the situation turns vice versa, that is when the partnerships show under achieving performance or patterns. Less complexity products when made, leads to alternative solutions within reach. Effectively, DSM wants itself always to be less dependent on non dependable and under achieving suppliers (Van Weele 2006). Importance of kraljic portfolio model is clearly understood when it is actually put into use and customizing of the same would enhance the solving capability of the strategic issues that are at hand. The portfolio model provides guidelines for a better supplier and purchasing strategies. This case study clearly suggests us the importance of placing commodities at different quadrants of the matrix to help in development of the purchasing strategies (Van Weele 2006).

Iron Cage - Max Webers Theory of Rationality

Iron Cage - Max Webers Theory of Rationality One of the theoretical concepts that Max Weber, founding sociologist, is most well known for is the iron cage. Weber first presented this theory in his important and widely taught work,  The Protestant Ethic and the Spirit of Capitalism, however, he  wrote in German, so never actually used the phrase himself. It was American sociologist Talcott Parsons who coined it, in his original translation of Webers book, published in 1930. In the original work, Weber referred to a  stahlhartes Gehuse, which literally translated means housing hard as steel. Parsons translation into iron cage, though, is largely accepted as an accurate rendering of the metaphor offered by Weber. Understanding Webers Iron Cage In  The Protestant Ethic and the Spirit of Capitalism, Weber presented a carefully researched historical account of how a strong Protestant work ethic and belief in living frugally helped foster the development of the capitalist economic system in the Western world. Weber explained that as the force of Protestantism decreased in social life over time, the system of capitalism remained, as did the social structure and principles of bureaucracy that had evolved along with it. This bureaucratic social structure, and the values, beliefs, and worldviews that supported and sustained it, became central to shaping social life. It was this very phenomenon that Weber conceived of as an iron cage. The reference to this concept comes on page 181 of Parsons translation. It reads: The Puritan wanted to work in a calling; we are forced to do so. For when asceticism was carried out of monastic cells into everyday life, and began to dominant worldly morality, it did its part in building the tremendous cosmos of the modern economic order. Simply put, Weber suggests that the technological and economic relationships that organized and grew out of capitalist production became themselves fundamental forces in society. Thus, if you are born into a society organized this way, with the division of labor and hierarchical social structure that comes with it, you cant help but live within this system. As such, ones life and worldview are shaped by it to such an extent that one probably cant even imagine what an alternative way of life would look like. So, those born into the cage live out its dictates, and in doing so, reproduce the cage in perpetuity. For this reason, Weber considered the iron cage a massive hindrance to freedom. Why Sociologists Embrace Webers Iron Cage This concept proved very useful to social theorists and researchers who followed Weber. Most notably, the  critical theorists associated with the Frankfurt School  in Germany, who were active during the middle of the twentieth century, elaborated on this concept. They witnessed further technological developments and their impact on capitalist production and culture  and saw that these only intensified the ability of the iron cage to shape and constrain our behavior and thought. Webers concept remains important to sociologists today because the iron cage of techno-rational thought, practices, relations, and capitalism   now a global system   shows no signs of disintegrating anytime soon. The influence of this iron cage leads to some very serious problems that social scientists and others are now working to solve. For example, how can we overcome the force of the iron cage to address the threats of climate change, produced by the very cage itself? And, how can we convince people that the system within the cage is  not  working in their best interest, evidenced by the shocking wealth inequality that divides many Western nations?

Explain the relevance of marketing concept to the 21st century Essay - 2

Explain the relevance of marketing concept to the 21st century business of Boots - Essay Example Marketing develops an important link between the material requirements of a society and economic models of response. Marketing generally satisfies the wants and needs through significant long term relationship and exchange process. Leading organizations are implementing several effective marketing tools in order to increase their core competencies and market share (Masterson and Pickton, 2010, p.499). The organization achieves financial success based on their core marketing ability. Effective marketing strategy creates demand for the product. Marketing concept is the key ingredient of marketing. The essay will explain the significance of marketing concept to the boots’ business in this 21st century. Marketing Concept It is important for the organizations to understand the facts and significance of marketing concepts before implementing any marketing strategy. Effective understanding of marketing concept helps the organizations to develop effective marketing strategy based on t he current market demand and customer preferences. Marketing concept is an important management philosophy that helps an organization to achieve organizational goals and objectives through the stated customer recognition and satisfaction and intangible needs and wants of customers (Drummond and Ensor, 2005, p.51). Marketing concept can be classified into two different approaches, such as earlier approaches and contemporary approaches. The marketing orientation developed from traditional marketing orientations like product orientation, production orientation, selling orientation. On the other hand, contemporary marketing concept approaches majorly focuses on relationship management or relationship marketing that includes industrial marketing, customer approaches and business marketing (Shanker, 2002, p.268). The leading organizations in this 21st century are trying to implement social marketing strategy in order to focus on the society benefits. Earlier the marketers used to follow t raditional marketing concepts namely product marketing, production marketing and selling marketing. In 20th century the organizations implemented traditional marketing strategy due to low competitive market and lack of diverse market demand. After the Second World War several organizations tried to expand their business operations in various global market places due to globalization. On the other hand, the market demand and customer’s preference significantly increased due to diversified business practices of several organizations (Wheelen and Hunger, 2011, p.121). Now-a-days, various organizations are competing with each other for their products of a similar segment to secure effective market share. Therefore, people are consuming products of different brands based on the quality and prices of products and services. In 21st century, the organizations are trying to implement several unique marketing strategies based on the market demand and customer preference to attract the customers towards their products and services. In this modern era, the organizations are trying to implement holistic marketing concept in order to achieve significant competitive advantages (Pride and Ferrell, 2004, p.78). This marketing concept is based on design, development and implementation of several marketing programmes, activities

Websites search Essay Example | Topics and Well Written Essays - 500 words

Websites search - Essay Example It is very helpful in the provision of details concerning family and community involvement in children programs. Fine: Family Involvement Network of Educators provided at Harvard Family Research Project (http://www.hfrp.org/) has a lot of resources and publications concerning family involvement that can be employed in classrooms for instructing. The site is very supportive as it provides a lot of publications collectively at one place. National Coalition for Parent Involvement in Education (http://www.ncpie.org/) is an informative site that contains a lot of information regarding family and development, family-community organizations, family-education organizations and parents and families. This can be used for teaching in classrooms by reading and facilitating parents with the reading material. National Center for Family and Community Connections with Schools (http://www.sedl.org/connections/) contains family and community based researches and practical works informing about how students at schools can be supported by families and communities. It will be helpful in classroom instructions because it contains a huge collection of resources concerning family and community connections with schools. LDonline (http://www.ldonline.org/educators) is a website that gives detailed data related to disability and ADHD (Attention Deficit Hyperactivity Disorder). The site is very useful in terms of its informative material. The site is rich with information concerning learning about disabilities and ADHD. Information can be retrieved from this site in order to help out students in terms of instruction concerning disabilities. BC Ministry of Education: Special Education (http://www.bced.gov.bc.ca/specialed/) contains resource documents and policies concerning education of special children. Hence, this site contains a huge amount of data of resource documents concerning students with disabilities. The information provided at this site can be

Cause And Effect Paper Essay Example | Topics and Well Written Essays - 500 words

Cause And Effect Paper - Essay Example Before the internet revolution era, available lines for communication were not only expensive but also slow and cumbersome; these lines were also subject to physical damages and other interference hampering their applications. However, revolutionized internet allows million users to share costs of high-performing circuits, reduce the number of lines and provide automatic re-routing of information in case of any interference. Internet has significantly contributed to effective and timely communication across the globe. Some of its significant contributions include timely sharing of information. Sharing information and occurrences across the world is an undemanding experience. Access to global news is easy using internet connectivity. Social networking renders it easy to access news through platforms such as Google+, Twitter and Facebook. Besides easy sharing of information, obtaining relevant and educational literature from online scholarly databases is easier and efficient for its users to access than before internet invention. Nearly all forms of literature are now easily retrievable from the internet. Easier retrieval of information from the internet is a cause of revolution in the education sector (Livingstone, 2009). Learners can do online research using information from Google books, academic database and other scholarly sites. Communications within cities, across borders and overseas is now easier and faster with internet than before the invention of internet. E-mail services render sending of information easier, faster and cheaper compared to conventional methods. The internet is a platform that provides convenience undertaking online transactions. Online business transactions improve lives; business partners need not to physically acquire goods and services after invent of online transactions. In some insta nces, people need no to be physically present at

High Performance Wireless Telecommunications Modulation

High Performance Wireless Telecommunications Modulation Introduction The primary goal of the project is to analyze of OFDM system and to assess the suitability of OFDM as a modulation technique for wireless communications. In the part of project is covered two leading successfully implementation of OFDM based technologies are Digital Video Broadcasting (DVB-T and DVB-H) and Long Term Evolution (LTE advanced for 4G). Wireless communications is an emerging field, which has seen enormous growth in the last several years. The huge uptake rate of mobile phone technology, Wireless Local Area Networks (WLAN) and the exponential growth of the Internet have resulted in an increased demand for new methods of obtaining high capacity wireless networks. For cellular mobile applications, we will see in the near future a complete convergence of mobile phone technology, computing, Internet access, and potentially many multimedia applications such as video and high quality audio. In fact, some may argue that this convergence has already largely occurred, with the advent of being able to send and receive data using a notebook computer and a mobile phone. The goal of third and fourth generation mobile networks is to provide users with a high data rate, and to provide a wider range of services, such as voice communications, videophones, and high speed Internet access. The higher data rate of future mobile networks will be achieved by increasing the amount of spectrum allocated to the service and by improvements in the spectral efficiency. OFDM is a potential candidate for the physical layer of fourth generation mobile systems. Basic Principles of OFDM OFDM overview The Orthogonal Frequency Division Multiplexing (OFDM) is a modulation technique where multiple low data rate carriers are combined by a transmitter to form a composite high data rate transmission. The first commercial use of OFDM in the communication field was in the 1980s, and it was later widely used in the broadcast audio and video field in the 1990s in such areas as, ADSL, VHDSL, ETSI standard digital audio broadcast (DAB), digital video broadcast (DVB), and high-definition digital TV (HDTV). Digital signal processing makes OFDM possible. To implement the multiple carrier scheme using a bank of parallel modulators would not be very efficient in analog hardware. However, in the digital domain, multi-carrier modulation can be done efficiently with currently available DSP hardware and software. Not only can it be done, but it can also be made very flexible and programmable. This allows OFDM to make maximum use of available bandwidth and to be able to adapt to changing system requirements. Figure 1 is illustrated, Instead of separate modulators; the outgoing waveform is created by executing a high-speed inverse DFT on a set of time-samples of the transmitted data (post modulation). The output of the DFT can be directly modulated onto the outgoing carrier, without requiring any other components. Each carrier in an OFDM system is a sinusoid with a frequency that is an integer multiple of a base or fundamental sinusoid frequency. Therefore, each carrier is like a Fourier series component of the composite signal. In fact, it will be shown later that an OFDM signal is created in the frequency domain, and then transformed into the time domain via the Discrete Fourier Transform (DFT). Two periodic signals are orthogonal when the integral of their product, over one period, is equal to zero. This is true of certain sinusoids as illustrated in Equation 1. Definition of Orthogonal The carriers of an OFDM system are sinusoids that meet this requirement because each one is a multiple of a fundamental frequency. Each one has an integer number of cycles in the fundamental period. [2, 145-153; 6] The importantance of being orthogonal The main concept in OFDM is orthogonality of the sub-carriers.Since the carriers are all sine/cosine wave, we know that area under one period of a sine or a cosine wave is zero. Lets take a sine wave of frequency m and multiply it by a sinusoid (sine or a cosine) of a frequency n, where both m and n are integers. The integral or the area under this product is given by These two components are each a sinusoid, so the integral is equal to zero over one period. When we multiply a sinusoid of frequency n by a sinusoid of frequency m/n the area under the product is zero. In general for all integers n and m , sin(mx), cos(mx), cos(nx) , sin(nx) are all orthogonal to each other. These frequencies are called harmonics. Making the subcarriers mathematically orthogonal was a breakthrough for OFDM because it enables OFDM receivers to separate the subcarriers via an FFT and eliminate the guard bands. As figure 3 shows, OFDM subcarriers can overlap to make full use of the spectrum, but at the peak of each subcarrier spectrum, the power in all the other subcarriers is zero. OFDM therefore offers higher data capacity in a given spectrum while allowing a simpler system design. Creating orthogonal subcarriers in the transmitter is easy using an inverse FFT. To ensure that this orthogonality is maintained at the receiver (so that the subcarriers are not misaligned), the system must keep the transmitter and receiver clocks closely synchronizedwithin 2 parts per million in 802.11a systems. The 802.11a standard therefore dedicates four of its 52 subcarriers as pilots that enable phase-lock loops in the receiver to track the phase and frequency of the incoming signal. The 802.11a standard therefore dedicates four of its 52 subcarriers as pilots that enable phase-lock loops in the receiver to track the phase and frequency of the incoming signal. This method also eliminates low-frequency phase noise.Separating the subcarriers via an FFT require about an order of magnitude fewer multiply-accumulate operations than individually filtering each carrier. In general, an FFT implementation is much simpler than the RAKE receivers used for CDMA and the decision-feedback equalizers for TDMA.This idea are key to understanding OFDM. The orthogonality allows simultaneously transmission on a lot of sub- carriers in a tight frequency space without interference form each other. In essence this is similar to CDMA, where codes are used to make data sequences independent (also orthogonal) which allows many independent users to transmitin same space successfully.[2, 153-154; 6 ; 7] OFDM Operation Preliminary Concepts When the DFT (Discrete Fourier Transform) of a time signal is taken, the frequency domain results are a function of the time sampling period and the number of samples as shown in Figure 4. The fundamental frequency of the DFT is equal to 1/NT (1/total sample time). Each frequency represented in the DFT is an integer multiple of the fundamental frequency. Parameter Mapping from Time to Frequency for the DFT The maximum frequency that can be represented by a time signal sampled at rate 1/T is fmax = 1/2T as given by the Nyquist sampling theorem. This frequency is located in the center of the DFT points. All frequencies beyond that point are images of the representative frequencies. The maximum frequency bin of the DFT is equal to the sampling frequency (1/T) minus one fundamental (1/NT).The IDFT (Inverse Discrete Fourier Transform) performs the opposite operation to the DFT. It takes a signal defined by frequency components and converts them to a time signal. The parameter mapping is the same as for the DFT. The time duration of the IDFT time signal is equal to the number of DFT bins (N) times the sampling period (T).It is perfectly valid to generate a signal in the frequency domain, and convert it to a time domain equivalent for practical use (The frequency domain is a mathematical tool used for analysis. Anything usable by the real world must be converted into a real, time domain signal). This is how modulation is applied in OFDM. In practice the Fast Fourier Transform (FFT) and IFFT are used in place of the DFT and IDFT, so all further references will be to FFT and IFFT.[1 ,118 ; 4] Definition of Carriers The maximum number of carriers used by OFDM is limited by the size of the IFFT. This is determined as follows in Equation 2. OFDM Carrier Count In order to generate a real-valued time signal, OFDM (frequency) carriers must be defined in complex conjugate pairs, which are symmetric about the Nyquist frequency (fmax). This puts the number of potential carriers equal to the IFFT size/2. The Nyquist frequency is the symmetry point, so it cannot be part of a complex conjugate pair. The DC component also has no complex conjugate. These two points cannot be used as carriers so they are subtracted from the total available. If the carriers are not defined in conjugate pairs, then the IFFT will result in a time domain signal that has imaginary components. This must be a viable option as there are OFDM systems defined with carrier counts that exceed the limit for real-valued time signals given in Equation 2.In general, a system with IFFT size 256 and carrier count 216. This design must result in a complex time waveform. Further processing would require some sort of quadrature technique (use of parallel sine and cosine processing paths). In this report, only real-value time signals will be treated, but in order to obtain maximum bandwidth efficiency from OFDM, the complex time signal may be preferred (possibly an analogous situation to QPSK vs. BPSK). Equation 2, for the complex time waveform, has all IFFT bins available as carriers except the DC bin. Both IFFT size and assignment (selection) of carriers can be dynamic. The transmitter and receiver just have to use the same parameters. This is one of the advantages of OFDM. Its bandwidth usage (and bit rate) can be varied according to varying user requirements. A simple control message from a base station can change a mobile units IFFT size and carrier selection.[2,199-206; 4] Modulation Binary data from a memory device or from a digital processing stream is used as the modulating (baseband) signal. The following steps may be carried out in order to apply modulation to the carriers in OFDM: combine the binary data into symbols according to the number of bits/symbol selected convert the serial symbol stream into parallel segments according to the number of carriers, and form carrier symbol sequences apply differential coding to each carrier symbol sequence convert each symbol into a complex phase representation assign each carrier sequence to the appropriate IFFT bin, including the complex conjugates take the IFFT of the result OFDM modulation is applied in the frequency domain. Figure 5 and Figure 6 give an example of modulated OFDM carriers for one symbol period, prior to IFFT. OFDM Carrier Magnitude prior to IFFT For this example, there are 4 carriers, the IFFT bin size is 64, and there is only 1 bit per symbol. The magnitude of each carrier is 1, but it could be scaled to any value. The phase for each carrier is either 0 or 180 degrees, according to the symbol being sent. The phase determines the value of the symbol (binary in this case, either a 1 or a 0). In the example, the first 3 bits (the first 3 carriers) are 0, and the 4th bit (4th carrier) is a 1. OFDM Carrier Phase prior to IFFT Note that the modulated OFDM signal is nothing more than a group of delta (impulse) functions, each with a phase determined by the modulating symbol. In addition, note that the frequency separation between each delta is proportional to 1/N where N is the number of IFFT bins. The frequency domain representation of the OFDM is described in Equation 3. OFDM Frequency Domain Representation (one symbol period) After the modulation is applied, an IFFT is performed to generate one symbol period in the time domain. The IFFT result is shown in 7. It is clear that the OFDM signal has varying amplitude. It is very important that the amplitude variations be kept intact as they define the content of the signal. If the amplitude is clipped or modified, then an FFT of the signal would no longer result in the original frequency characteristics, and the modulation may be lost. This is one of the drawbacks of OFDM, the fact that it requires linear amplification. In addition, very large amplitude peaks may occur depending on how the sinusoids line up, so the peak-to-average power ratio is high. This means that the linear amplifier has to have a large dynamic range to avoid distorting the peaks. The result is a linear amplifier with a constant, high bias current resulting in very poor power efficiency. OFDM Signal, 1 Symbol Period Figure 8 is provided to illustrate the time components of the OFDM signal. The IFFT transforms each complex conjugate pair of delta functions (each carrier) into a real-valued, pure sinusoid. Figure 8 shows the separate sinusoids that make up the composite OFDM waveform given in Figure 7. The one sinusoid with 180 phase shift is clearly visible as is the frequency difference between each of the 4 sinusoids. Transmission The key to the uniqueness and desirability of OFDM is the relationship between the carrier frequencies and the symbol rate. Each carrier frequency is separated by a multiple of 1/NT (Hz). The symbol rate (R) for each carrier is 1/NT (symbols/sec). The effect of the symbol rate on each OFDM carrier is to add a sin(x)/x shape to each carriers spectrum. The nulls of the sin(x)/x (for each carrier) are at integer multiples of 1/NT. The peak (for each carrier) is at the carrier frequency k/NT. Therefore, each carrier frequency is located at the nulls for all the other carriers. This means that none of the carriers will interfere with each other during transmission, although their spectrums overlap. The ability to space carriers so closely together is very bandwidth efficient. OFDM Time Waveform Figure 9 shows the OFDM time waveform for the same signal. There are 100 symbol periods in the signal. Each symbol period is 64 samples long (100 x 64 = 6400 total samples). Each symbol period contains 4 carriers each of which carries 1 symbol. Each symbol carries 1 bit. Note that Figure 9 again illustrates the large dynamic range of the OFDM waveform envelope. OFDM Spectrum Figure 10 shows the spectrum for of an OFDM signal with the following characteristics: 1 bit / symbol 100 symbols / carrier (i.e. a sequence of 100 symbol periods) 4 carriers 64 IFFT bins spectrum averaged for every 20 symbols (100/20 = 5 averages) Red diamonds mark all of the available carrier frequencies. Note that the nulls of the spectrums line up with the unused frequencies. The four active carriers each have peaks at carrier frequencies. It is clear that the active carriers have nulls in their spectrums at each of the unused frequencies (otherwise, the nulls would not exist). Although it cannot be seen in the figure, the active frequencies also have spectral nulls at the adjacent active frequencies. It is not currently practical to generate the OFDM signal directly at RF rates, so it must be up converted for transmission. To remain in the discrete domain, the OFDM could be upsampled and added to a discrete carrier frequency. This carrier could be an intermediate frequency whose sample rate is handled by current technology. It could then be converted to analog and increased to the final transmit frequency using analog frequency conversion methods. Alternatively, the OFDM modulation could be immediately converted to analog and directly increased to the desired RF transmits frequency. Either way, the selected technique would have to involve some form of linear AM (possibly implemented with a mixer). [1, 122-125; 6] Reception and Demodulation The received OFDM signal is down converted (in frequency) and taken from analog to digital. Demodulation is done in the frequency domain (just as modulation was). The following steps may be taken to demodulate the OFDM: partition the input stream into vectors representing each symbol period take the FFT of each symbol period vector extract the carrier FFT bins and calculate the phase of each calculate the phase difference, from one symbol period to the next, for each carrier decode each phase into binary data sort the data into the appropriate order OFDM Carrier Magnitude following FFT Figure 11 and Figure 12 show the magnitude and spectrum of the FFT for one received OFDM symbol period. For this example, there are 4 carriers, the IFFT bin size is 64, there is 1 bit per symbol, and the signal was sent through a channel with AWGN having an SNR of 8 dB. The figures show that, under these conditions, the modulated symbols are very easy to recover. OFDM Carrier Phase following FFT In Figure 12 that the unused frequency bins contain widely varying phase values. These bins are not decoded, so it does not matter, but the result is of interest. Even if the noise is removed from the channel, these phase variations still occur. It must be a result of the IFFT/FFT operations generating very small complex values (very close to 0) for the unused carriers. The phases are a result of these values. [1, 125 -128; 3] OFDM transceiver OFDM signals are typically generated digitally due to the difficulty in creating large banks of phase lock oscillators and receivers in the analog domain. Figure 13 shows the block diagram of a typical OFDM transceiver. The transmitter section converts digital data to be transmitted, into a mapping of subcarrier amplitude and phase. It then transforms this spectral representation of the data into the time domain using an Inverse Discrete Fourier Transform (IDFT). The Inverse Fast Fourier Transform (IFFT) performs the same operations as an IDFT, except that it is much more computationally efficiency, and so is used in all practical systems. In order to transmit the OFDM signal the calculated time domain signal is then mixed up to the required frequency. Block diagram showing a basic OFDM transceiver [3] The receiver performs the reverse operation of the transmitter, mixing the RF signal to base band for processing, then using a Fast Fourier Transform (FFT) to analyze the signal in the frequency domain. The amplitude and phase of the subcarriers is then picked out and converted back to digital data. The IFFT and the FFT are complementary function and the most appropriate term depends on whether the signal is being received or generated. In cases where the Signal is independent of this distinction then the term FFT and IFFT is used interchangeably. [1, 125 -128, 3] Analysis of OFDM characteristics Guard Period OFDM demodulation must be synchronized with the start and end of the transmitted symbol period. If it is not, then ISI will occur (since information will be decoded and combined for 2 adjacent symbol periods). ICI will also occur because orthogonality will be lost (integrals of the carrier products will no longer be zero over the integration period), To help solve this problem, a guard interval is added to each OFDM symbol period. The first thought of how to do this might be to simply make the symbol period longer, so that the demodulator does not have to be so precise in picking the period beginning and end, and decoding is always done inside a single period. This would fix the ISI problem, but not the ICI problem. If a complete period is not integrated (via FFT), orthogonality will be lost. The effect of ISI on an OFDM signal can be further improved by the addition of a guard period to the start of each symbol. This guard period is a cyclic copy that extends the length of the symbol waveform. Each subcarrier, in the data section of the symbol, (i.e. the OFDM symbol with no guard period added, which is equal to the length of the IFFT size used to generate the signal) has an integer number of cycles. Because of this, placing copies of the symbol end-to-end results in a continuous signal, with no discontinuities at the joins. Thus by copying the end of a symbol and appending this to the start results in a longer symbol time. Addition of a guard period to an OFDM signal [3] In Figure 14, The total length of the symbol is Ts=TG + TFFT, where Ts is the total length of the symbol in samples, TG is the length of the guard period in samples, and TFFT is the size of the IFFT used to generate the OFDM signal. In addition to protecting the OFDM from ISI, the guard period also provides protection against time-offset errors in the receiver. For an OFDM system that has the same sample rate for both the transmitter and receiver, it must use the same FFT size at both the receiver and transmitted signal in order to maintain subcarrier orthogonality. Each received symbol has TG + TFFT samples due to the added guard period. The receiver only needs TFFT samples of the received symbol to decode the signal. The remaining TG samples are redundant and are not needed. For an ideal channel with no delay spread the receiver can pick any time offset, up to the length of the guard period, and still get the correct number of samples, without crossing a symbol boundary. Function of the guard period for protecting against ISI [3] Figure 15 shows this effect. Adding a guard period allows time for the transient part of the signal to decay, so that the FFT is taken from a steady state portion of the symbol. This eliminates the effect of ISI provided that the guard period is longer than the delay spread of the radio channel. The remaining effects caused by the multipath, such as amplitude scaling and phase rotation are corrected for by channel equalization. In order to avoid ISI and ICI, the guard period must be formed by a cyclic extension of the symbol period. This is done by taking symbol period samples from the end of the period and appending them to the front of the period. The concept of being able to do this, and what it means, comes from the nature of the IFFT/FFT process. When the IFFT is taken for a symbol period (during OFDM modulation), the resulting time sample sequence is technically periodic. This is because the IFFT/FFT is an extension of the Fourier Transform which is an extension of the Fourier Series for periodic waveforms. All of these transforms operate on signals with either real or manufactured periodicity. For the IFFT/FFT, the period is the number of samples used. Guard Period via Cyclic Extension With the cyclic extension, the symbol period is longer, but it represents the exact same frequency spectrum. As long as the correct number of samples are taken for the decode, they may be taken anywhere within the extended symbol. Since a complete period is integrated, orthogonality is maintained. Therefore, both ISI and ICI are eliminated. Note that some bandwidth efficiency is lost with the addition of the guard period (symbol period is increased and symbol rate is decreased) [2,154-160, 3] Windowing The OFDM signal is made up of a series of IFFTs that are concatenated to each other. At each symbol period boundary, there is a signal discontinuity due to the differences between the end of one period and the start of the next. These discontinuities can cause high frequency spectral noise to be generated (because they look like very fast transitions of the time waveform). To avoid this, a window function (Hamming, Hanning, Blackman, ) may be applied to each symbol period. The window function would attenuate the time waveform at the start and the end of each period, so that the discontinuities are smaller, and the high frequency noise is reduced. However, this attenuation distorts the signal and some of the desired frequency content is lost.[1, 121;2 154] Multipath Characteristics OFDM avoids frequency selective fading and ISI by providing relatively long symbol periods for a given data rate. This is illustrated in Figure 17. For a given transmission channel and a given source data rate, OFDM can provide better multipath characteristics than a single carrier. OFDM vs. Single Carrier, Multipath Characteristic Comparison However, since the OFDM carriers are spread over a frequency range, there still may be some frequency selective attenuation on a time-varying basis. A deep fade on a particular frequency may cause the loss of data on that frequency for a given time, but the use of Forward Error Coding can fix it. If a single carrier experienced a deep fade, too many consecutive symbols may be lost and correction coding may be ineffective. [8] Bandwidth A comparison of RF transmits bandwidth between OFDM and a single carrier is shown in Figure 18 (using the same example parameters as in Figure 17). OFDM Bandwidth Efficiency In Figure 18, the calculations show that OFDM is more bandwidth efficient than a single carrier. Note that another efficient aspect of OFDM is that a single transmitters bandwidth can be increased incrementally by addition of more adjacent carriers. In addition, no bandwidth buffers are needed between transmit bandwidths of separate transmitters as long as orthogonality can be maintained between all the carriers.[2, 161-163; 8; 9] Physical Implementation Since OFDM is carried out in the digital domain, there are many ways it can be implemented. Some options are provided in the following list. Each of these options should be viable given current technology: ASIC (Application Specific Integrated Circuit) ASICs are the fastest, smallest, and lowest power way to implement OFDM Cannot change the ASIC after it is built without designing a new chip General-purpose Microprocessor or MicroController PowerPC 7400 or other processor capable of fast vector operations Highly programmable Needs memory and other peripheral chips Uses the most power and space, and would be the slowest Field-Programmable Gate Array (FPGA) An FPGA combines the speed, power, and density attributes of an ASIC with the programmability of a general purpose processor. An FPGA could be reprogrammed for new functions by a base station to meet future (currently unknown requirements).This should be the best choice.[9] OFDM uses in DVB (Digital Video Broadcasting) DVB (Digital Video Broadcast) is a set of standards for the digital transmission of video and audio streams, and also data transmission. The DVB standards are maintained by the DVB Project, which is an industry-led consortium of over 260 broadcasters, manufacturers, network operators, software developers, regulatory bodies and others in over 35 countries. DVB has been implemented over satellite (DVB-S, DVB-S2), cable (DVB-C), terrestrial broadcasting (DVB-T), and handheld terminals (DVB-H). the DVB standard following the logical progression of signal processing steps, as well as source and channel coding, COFDM modulation, MPEG compression and multiplexing methods, conditional access and set-top box Technology. In this project is presented an investigation of two OFDM based DVB standards, DVB-T and DVB-H. DVB-T (Digital Video Broadcasting Terrestrial) The first Terrestrial Digital Video Broadcasting pilot transmissions were started in the late 90s, and the first commercial system was established in Great Britain. In the next few years the digital broadcasting system has been set up in many countries, and the boom of the digital terrestrial transmission is estimated in the next few years, while the analogue transmission will be cancelled within about 15 years. The greatest advantage of the digital system is the effective use of the frequency spectrum and its lower radiated power in comparison with the analogue transmission, while the covered area remains the same. Another key feature is the possibility of designing a so-called Single Frequency Network (SFN), which means that the neighboring broadcast stations use the same frequency and the adjacent signals dont get interfered. The digital system transmits a data stream, which means that not only television signals but data communication (e.g. Internet service) may be used according to the demands. The data stream consists of an MPEG-2 bit stream, which means a compression is used, enabling the transfer of even 4 or 5 television via the standard 8 MHz wide TV channel. For the viewer, the main advantages are the perfect, noise-free picture, CD quality sound, and easier handling, as well as services like Super Teletext, Electronic Programme Guide, interactivity and mobility.[11, 251-253] Modulation technique in DVB-T The DVB-T Orthogonal Frequency Division Multiplexing (OFDM) modulation system uses multi-carrier transmission. There are 2 modes, the so-called 2k and 8k modes, using 1705 and 6817 carriers respectively, with each carrier modulated separately and transmitted in the 8 MHz TV channel. The common modulation for the carriers is typically QPSK, 16-QAM or 64-QAM. Each signal can be divided into two, so-called „In Phase (I) and „Quadrature Phase components, being a 90Â ° phase shift between them. The constellation diagram and the bit allocation is shown in bellow 16-QAM constellation diagram and bit allocation [6] This modulation can be demonstrated in the constellation diagram, where the 2 axes represent the 2 components (I and Q). In case of using 16-QAM modulation, the number of states is 16, so 1 symbol represents 4 bits. [11, 255; 6; 14] Bir errors If we simulate all the carriers in the constellation diagram we get not just 1 discrete point, but many points, forming a „cloud and representing each state. In case of additive noise the „cloud gets bigger and the receiver may decide incorrectly, resulting in bit errors. Figure 2 shows the measured constellation diagram without and with additive noise. Measured 16-QAM constellation diagram a) without additive noise b) with additive noise [6] To ensure perfect picture quality, the DVB-T system uses a 2 level error correction (Reed-Solomon and Viterbi). This corrects the bad bits at an even 10-4 Bit Error Rate (BER) and enables error-free data transmission. [13, 32-36] The multi-carrier structure The structure of carriers can be illustrated also in the function of time (Figure 20). The horizontal axis is the frequency and the vertical axis is the time. The 8 MHz channel consists of many carriers, placed 4462 Hz or 1116 Hz far from each other according to the modulation mode (2k or 8k). Structure of OFDM carriers [13] There are some reserved, so-called Transmission Parameter Signalling (TPS) carriers that do not transfer payload, just provide transmission mode information for the receiver, so the total number of useful carriers is 1512 and 6048 respectively in the two transmission modes, and the resultant bit rate is between 4,97 and 31,66 Mbit/s, depending on the modulation (QPSK, 16-QAM or 64-QAM), the transmission mode (2k or 8k), the Code Rate (CR) used for error correction and the selected Guard Interval (GI). This guard interval means that there is a small time gap between each symbol, so the transmission is not continuous. This guarding time enables perfect reception by eliminating the errors caused by multipath propagation.[4, 79-90; 13] Frequency spectrum In 2k mode, 1705 carriers are modulated in the 8 MHz TV channel, so each carrier is 4462 Hz far from its neighbor, while in 8k mode this distance is 1116 Hz. In digital broadcasting, there are no vision and sound carriers, so the power for each carrier is the same. This mean High Performance Wireless Telecommunications Modulation High Performance Wireless Telecommunications Modulation Introduction The primary goal of the project is to analyze of OFDM system and to assess the suitability of OFDM as a modulation technique for wireless communications. In the part of project is covered two leading successfully implementation of OFDM based technologies are Digital Video Broadcasting (DVB-T and DVB-H) and Long Term Evolution (LTE advanced for 4G). Wireless communications is an emerging field, which has seen enormous growth in the last several years. The huge uptake rate of mobile phone technology, Wireless Local Area Networks (WLAN) and the exponential growth of the Internet have resulted in an increased demand for new methods of obtaining high capacity wireless networks. For cellular mobile applications, we will see in the near future a complete convergence of mobile phone technology, computing, Internet access, and potentially many multimedia applications such as video and high quality audio. In fact, some may argue that this convergence has already largely occurred, with the advent of being able to send and receive data using a notebook computer and a mobile phone. The goal of third and fourth generation mobile networks is to provide users with a high data rate, and to provide a wider range of services, such as voice communications, videophones, and high speed Internet access. The higher data rate of future mobile networks will be achieved by increasing the amount of spectrum allocated to the service and by improvements in the spectral efficiency. OFDM is a potential candidate for the physical layer of fourth generation mobile systems. Basic Principles of OFDM OFDM overview The Orthogonal Frequency Division Multiplexing (OFDM) is a modulation technique where multiple low data rate carriers are combined by a transmitter to form a composite high data rate transmission. The first commercial use of OFDM in the communication field was in the 1980s, and it was later widely used in the broadcast audio and video field in the 1990s in such areas as, ADSL, VHDSL, ETSI standard digital audio broadcast (DAB), digital video broadcast (DVB), and high-definition digital TV (HDTV). Digital signal processing makes OFDM possible. To implement the multiple carrier scheme using a bank of parallel modulators would not be very efficient in analog hardware. However, in the digital domain, multi-carrier modulation can be done efficiently with currently available DSP hardware and software. Not only can it be done, but it can also be made very flexible and programmable. This allows OFDM to make maximum use of available bandwidth and to be able to adapt to changing system requirements. Figure 1 is illustrated, Instead of separate modulators; the outgoing waveform is created by executing a high-speed inverse DFT on a set of time-samples of the transmitted data (post modulation). The output of the DFT can be directly modulated onto the outgoing carrier, without requiring any other components. Each carrier in an OFDM system is a sinusoid with a frequency that is an integer multiple of a base or fundamental sinusoid frequency. Therefore, each carrier is like a Fourier series component of the composite signal. In fact, it will be shown later that an OFDM signal is created in the frequency domain, and then transformed into the time domain via the Discrete Fourier Transform (DFT). Two periodic signals are orthogonal when the integral of their product, over one period, is equal to zero. This is true of certain sinusoids as illustrated in Equation 1. Definition of Orthogonal The carriers of an OFDM system are sinusoids that meet this requirement because each one is a multiple of a fundamental frequency. Each one has an integer number of cycles in the fundamental period. [2, 145-153; 6] The importantance of being orthogonal The main concept in OFDM is orthogonality of the sub-carriers.Since the carriers are all sine/cosine wave, we know that area under one period of a sine or a cosine wave is zero. Lets take a sine wave of frequency m and multiply it by a sinusoid (sine or a cosine) of a frequency n, where both m and n are integers. The integral or the area under this product is given by These two components are each a sinusoid, so the integral is equal to zero over one period. When we multiply a sinusoid of frequency n by a sinusoid of frequency m/n the area under the product is zero. In general for all integers n and m , sin(mx), cos(mx), cos(nx) , sin(nx) are all orthogonal to each other. These frequencies are called harmonics. Making the subcarriers mathematically orthogonal was a breakthrough for OFDM because it enables OFDM receivers to separate the subcarriers via an FFT and eliminate the guard bands. As figure 3 shows, OFDM subcarriers can overlap to make full use of the spectrum, but at the peak of each subcarrier spectrum, the power in all the other subcarriers is zero. OFDM therefore offers higher data capacity in a given spectrum while allowing a simpler system design. Creating orthogonal subcarriers in the transmitter is easy using an inverse FFT. To ensure that this orthogonality is maintained at the receiver (so that the subcarriers are not misaligned), the system must keep the transmitter and receiver clocks closely synchronizedwithin 2 parts per million in 802.11a systems. The 802.11a standard therefore dedicates four of its 52 subcarriers as pilots that enable phase-lock loops in the receiver to track the phase and frequency of the incoming signal. The 802.11a standard therefore dedicates four of its 52 subcarriers as pilots that enable phase-lock loops in the receiver to track the phase and frequency of the incoming signal. This method also eliminates low-frequency phase noise.Separating the subcarriers via an FFT require about an order of magnitude fewer multiply-accumulate operations than individually filtering each carrier. In general, an FFT implementation is much simpler than the RAKE receivers used for CDMA and the decision-feedback equalizers for TDMA.This idea are key to understanding OFDM. The orthogonality allows simultaneously transmission on a lot of sub- carriers in a tight frequency space without interference form each other. In essence this is similar to CDMA, where codes are used to make data sequences independent (also orthogonal) which allows many independent users to transmitin same space successfully.[2, 153-154; 6 ; 7] OFDM Operation Preliminary Concepts When the DFT (Discrete Fourier Transform) of a time signal is taken, the frequency domain results are a function of the time sampling period and the number of samples as shown in Figure 4. The fundamental frequency of the DFT is equal to 1/NT (1/total sample time). Each frequency represented in the DFT is an integer multiple of the fundamental frequency. Parameter Mapping from Time to Frequency for the DFT The maximum frequency that can be represented by a time signal sampled at rate 1/T is fmax = 1/2T as given by the Nyquist sampling theorem. This frequency is located in the center of the DFT points. All frequencies beyond that point are images of the representative frequencies. The maximum frequency bin of the DFT is equal to the sampling frequency (1/T) minus one fundamental (1/NT).The IDFT (Inverse Discrete Fourier Transform) performs the opposite operation to the DFT. It takes a signal defined by frequency components and converts them to a time signal. The parameter mapping is the same as for the DFT. The time duration of the IDFT time signal is equal to the number of DFT bins (N) times the sampling period (T).It is perfectly valid to generate a signal in the frequency domain, and convert it to a time domain equivalent for practical use (The frequency domain is a mathematical tool used for analysis. Anything usable by the real world must be converted into a real, time domain signal). This is how modulation is applied in OFDM. In practice the Fast Fourier Transform (FFT) and IFFT are used in place of the DFT and IDFT, so all further references will be to FFT and IFFT.[1 ,118 ; 4] Definition of Carriers The maximum number of carriers used by OFDM is limited by the size of the IFFT. This is determined as follows in Equation 2. OFDM Carrier Count In order to generate a real-valued time signal, OFDM (frequency) carriers must be defined in complex conjugate pairs, which are symmetric about the Nyquist frequency (fmax). This puts the number of potential carriers equal to the IFFT size/2. The Nyquist frequency is the symmetry point, so it cannot be part of a complex conjugate pair. The DC component also has no complex conjugate. These two points cannot be used as carriers so they are subtracted from the total available. If the carriers are not defined in conjugate pairs, then the IFFT will result in a time domain signal that has imaginary components. This must be a viable option as there are OFDM systems defined with carrier counts that exceed the limit for real-valued time signals given in Equation 2.In general, a system with IFFT size 256 and carrier count 216. This design must result in a complex time waveform. Further processing would require some sort of quadrature technique (use of parallel sine and cosine processing paths). In this report, only real-value time signals will be treated, but in order to obtain maximum bandwidth efficiency from OFDM, the complex time signal may be preferred (possibly an analogous situation to QPSK vs. BPSK). Equation 2, for the complex time waveform, has all IFFT bins available as carriers except the DC bin. Both IFFT size and assignment (selection) of carriers can be dynamic. The transmitter and receiver just have to use the same parameters. This is one of the advantages of OFDM. Its bandwidth usage (and bit rate) can be varied according to varying user requirements. A simple control message from a base station can change a mobile units IFFT size and carrier selection.[2,199-206; 4] Modulation Binary data from a memory device or from a digital processing stream is used as the modulating (baseband) signal. The following steps may be carried out in order to apply modulation to the carriers in OFDM: combine the binary data into symbols according to the number of bits/symbol selected convert the serial symbol stream into parallel segments according to the number of carriers, and form carrier symbol sequences apply differential coding to each carrier symbol sequence convert each symbol into a complex phase representation assign each carrier sequence to the appropriate IFFT bin, including the complex conjugates take the IFFT of the result OFDM modulation is applied in the frequency domain. Figure 5 and Figure 6 give an example of modulated OFDM carriers for one symbol period, prior to IFFT. OFDM Carrier Magnitude prior to IFFT For this example, there are 4 carriers, the IFFT bin size is 64, and there is only 1 bit per symbol. The magnitude of each carrier is 1, but it could be scaled to any value. The phase for each carrier is either 0 or 180 degrees, according to the symbol being sent. The phase determines the value of the symbol (binary in this case, either a 1 or a 0). In the example, the first 3 bits (the first 3 carriers) are 0, and the 4th bit (4th carrier) is a 1. OFDM Carrier Phase prior to IFFT Note that the modulated OFDM signal is nothing more than a group of delta (impulse) functions, each with a phase determined by the modulating symbol. In addition, note that the frequency separation between each delta is proportional to 1/N where N is the number of IFFT bins. The frequency domain representation of the OFDM is described in Equation 3. OFDM Frequency Domain Representation (one symbol period) After the modulation is applied, an IFFT is performed to generate one symbol period in the time domain. The IFFT result is shown in 7. It is clear that the OFDM signal has varying amplitude. It is very important that the amplitude variations be kept intact as they define the content of the signal. If the amplitude is clipped or modified, then an FFT of the signal would no longer result in the original frequency characteristics, and the modulation may be lost. This is one of the drawbacks of OFDM, the fact that it requires linear amplification. In addition, very large amplitude peaks may occur depending on how the sinusoids line up, so the peak-to-average power ratio is high. This means that the linear amplifier has to have a large dynamic range to avoid distorting the peaks. The result is a linear amplifier with a constant, high bias current resulting in very poor power efficiency. OFDM Signal, 1 Symbol Period Figure 8 is provided to illustrate the time components of the OFDM signal. The IFFT transforms each complex conjugate pair of delta functions (each carrier) into a real-valued, pure sinusoid. Figure 8 shows the separate sinusoids that make up the composite OFDM waveform given in Figure 7. The one sinusoid with 180 phase shift is clearly visible as is the frequency difference between each of the 4 sinusoids. Transmission The key to the uniqueness and desirability of OFDM is the relationship between the carrier frequencies and the symbol rate. Each carrier frequency is separated by a multiple of 1/NT (Hz). The symbol rate (R) for each carrier is 1/NT (symbols/sec). The effect of the symbol rate on each OFDM carrier is to add a sin(x)/x shape to each carriers spectrum. The nulls of the sin(x)/x (for each carrier) are at integer multiples of 1/NT. The peak (for each carrier) is at the carrier frequency k/NT. Therefore, each carrier frequency is located at the nulls for all the other carriers. This means that none of the carriers will interfere with each other during transmission, although their spectrums overlap. The ability to space carriers so closely together is very bandwidth efficient. OFDM Time Waveform Figure 9 shows the OFDM time waveform for the same signal. There are 100 symbol periods in the signal. Each symbol period is 64 samples long (100 x 64 = 6400 total samples). Each symbol period contains 4 carriers each of which carries 1 symbol. Each symbol carries 1 bit. Note that Figure 9 again illustrates the large dynamic range of the OFDM waveform envelope. OFDM Spectrum Figure 10 shows the spectrum for of an OFDM signal with the following characteristics: 1 bit / symbol 100 symbols / carrier (i.e. a sequence of 100 symbol periods) 4 carriers 64 IFFT bins spectrum averaged for every 20 symbols (100/20 = 5 averages) Red diamonds mark all of the available carrier frequencies. Note that the nulls of the spectrums line up with the unused frequencies. The four active carriers each have peaks at carrier frequencies. It is clear that the active carriers have nulls in their spectrums at each of the unused frequencies (otherwise, the nulls would not exist). Although it cannot be seen in the figure, the active frequencies also have spectral nulls at the adjacent active frequencies. It is not currently practical to generate the OFDM signal directly at RF rates, so it must be up converted for transmission. To remain in the discrete domain, the OFDM could be upsampled and added to a discrete carrier frequency. This carrier could be an intermediate frequency whose sample rate is handled by current technology. It could then be converted to analog and increased to the final transmit frequency using analog frequency conversion methods. Alternatively, the OFDM modulation could be immediately converted to analog and directly increased to the desired RF transmits frequency. Either way, the selected technique would have to involve some form of linear AM (possibly implemented with a mixer). [1, 122-125; 6] Reception and Demodulation The received OFDM signal is down converted (in frequency) and taken from analog to digital. Demodulation is done in the frequency domain (just as modulation was). The following steps may be taken to demodulate the OFDM: partition the input stream into vectors representing each symbol period take the FFT of each symbol period vector extract the carrier FFT bins and calculate the phase of each calculate the phase difference, from one symbol period to the next, for each carrier decode each phase into binary data sort the data into the appropriate order OFDM Carrier Magnitude following FFT Figure 11 and Figure 12 show the magnitude and spectrum of the FFT for one received OFDM symbol period. For this example, there are 4 carriers, the IFFT bin size is 64, there is 1 bit per symbol, and the signal was sent through a channel with AWGN having an SNR of 8 dB. The figures show that, under these conditions, the modulated symbols are very easy to recover. OFDM Carrier Phase following FFT In Figure 12 that the unused frequency bins contain widely varying phase values. These bins are not decoded, so it does not matter, but the result is of interest. Even if the noise is removed from the channel, these phase variations still occur. It must be a result of the IFFT/FFT operations generating very small complex values (very close to 0) for the unused carriers. The phases are a result of these values. [1, 125 -128; 3] OFDM transceiver OFDM signals are typically generated digitally due to the difficulty in creating large banks of phase lock oscillators and receivers in the analog domain. Figure 13 shows the block diagram of a typical OFDM transceiver. The transmitter section converts digital data to be transmitted, into a mapping of subcarrier amplitude and phase. It then transforms this spectral representation of the data into the time domain using an Inverse Discrete Fourier Transform (IDFT). The Inverse Fast Fourier Transform (IFFT) performs the same operations as an IDFT, except that it is much more computationally efficiency, and so is used in all practical systems. In order to transmit the OFDM signal the calculated time domain signal is then mixed up to the required frequency. Block diagram showing a basic OFDM transceiver [3] The receiver performs the reverse operation of the transmitter, mixing the RF signal to base band for processing, then using a Fast Fourier Transform (FFT) to analyze the signal in the frequency domain. The amplitude and phase of the subcarriers is then picked out and converted back to digital data. The IFFT and the FFT are complementary function and the most appropriate term depends on whether the signal is being received or generated. In cases where the Signal is independent of this distinction then the term FFT and IFFT is used interchangeably. [1, 125 -128, 3] Analysis of OFDM characteristics Guard Period OFDM demodulation must be synchronized with the start and end of the transmitted symbol period. If it is not, then ISI will occur (since information will be decoded and combined for 2 adjacent symbol periods). ICI will also occur because orthogonality will be lost (integrals of the carrier products will no longer be zero over the integration period), To help solve this problem, a guard interval is added to each OFDM symbol period. The first thought of how to do this might be to simply make the symbol period longer, so that the demodulator does not have to be so precise in picking the period beginning and end, and decoding is always done inside a single period. This would fix the ISI problem, but not the ICI problem. If a complete period is not integrated (via FFT), orthogonality will be lost. The effect of ISI on an OFDM signal can be further improved by the addition of a guard period to the start of each symbol. This guard period is a cyclic copy that extends the length of the symbol waveform. Each subcarrier, in the data section of the symbol, (i.e. the OFDM symbol with no guard period added, which is equal to the length of the IFFT size used to generate the signal) has an integer number of cycles. Because of this, placing copies of the symbol end-to-end results in a continuous signal, with no discontinuities at the joins. Thus by copying the end of a symbol and appending this to the start results in a longer symbol time. Addition of a guard period to an OFDM signal [3] In Figure 14, The total length of the symbol is Ts=TG + TFFT, where Ts is the total length of the symbol in samples, TG is the length of the guard period in samples, and TFFT is the size of the IFFT used to generate the OFDM signal. In addition to protecting the OFDM from ISI, the guard period also provides protection against time-offset errors in the receiver. For an OFDM system that has the same sample rate for both the transmitter and receiver, it must use the same FFT size at both the receiver and transmitted signal in order to maintain subcarrier orthogonality. Each received symbol has TG + TFFT samples due to the added guard period. The receiver only needs TFFT samples of the received symbol to decode the signal. The remaining TG samples are redundant and are not needed. For an ideal channel with no delay spread the receiver can pick any time offset, up to the length of the guard period, and still get the correct number of samples, without crossing a symbol boundary. Function of the guard period for protecting against ISI [3] Figure 15 shows this effect. Adding a guard period allows time for the transient part of the signal to decay, so that the FFT is taken from a steady state portion of the symbol. This eliminates the effect of ISI provided that the guard period is longer than the delay spread of the radio channel. The remaining effects caused by the multipath, such as amplitude scaling and phase rotation are corrected for by channel equalization. In order to avoid ISI and ICI, the guard period must be formed by a cyclic extension of the symbol period. This is done by taking symbol period samples from the end of the period and appending them to the front of the period. The concept of being able to do this, and what it means, comes from the nature of the IFFT/FFT process. When the IFFT is taken for a symbol period (during OFDM modulation), the resulting time sample sequence is technically periodic. This is because the IFFT/FFT is an extension of the Fourier Transform which is an extension of the Fourier Series for periodic waveforms. All of these transforms operate on signals with either real or manufactured periodicity. For the IFFT/FFT, the period is the number of samples used. Guard Period via Cyclic Extension With the cyclic extension, the symbol period is longer, but it represents the exact same frequency spectrum. As long as the correct number of samples are taken for the decode, they may be taken anywhere within the extended symbol. Since a complete period is integrated, orthogonality is maintained. Therefore, both ISI and ICI are eliminated. Note that some bandwidth efficiency is lost with the addition of the guard period (symbol period is increased and symbol rate is decreased) [2,154-160, 3] Windowing The OFDM signal is made up of a series of IFFTs that are concatenated to each other. At each symbol period boundary, there is a signal discontinuity due to the differences between the end of one period and the start of the next. These discontinuities can cause high frequency spectral noise to be generated (because they look like very fast transitions of the time waveform). To avoid this, a window function (Hamming, Hanning, Blackman, ) may be applied to each symbol period. The window function would attenuate the time waveform at the start and the end of each period, so that the discontinuities are smaller, and the high frequency noise is reduced. However, this attenuation distorts the signal and some of the desired frequency content is lost.[1, 121;2 154] Multipath Characteristics OFDM avoids frequency selective fading and ISI by providing relatively long symbol periods for a given data rate. This is illustrated in Figure 17. For a given transmission channel and a given source data rate, OFDM can provide better multipath characteristics than a single carrier. OFDM vs. Single Carrier, Multipath Characteristic Comparison However, since the OFDM carriers are spread over a frequency range, there still may be some frequency selective attenuation on a time-varying basis. A deep fade on a particular frequency may cause the loss of data on that frequency for a given time, but the use of Forward Error Coding can fix it. If a single carrier experienced a deep fade, too many consecutive symbols may be lost and correction coding may be ineffective. [8] Bandwidth A comparison of RF transmits bandwidth between OFDM and a single carrier is shown in Figure 18 (using the same example parameters as in Figure 17). OFDM Bandwidth Efficiency In Figure 18, the calculations show that OFDM is more bandwidth efficient than a single carrier. Note that another efficient aspect of OFDM is that a single transmitters bandwidth can be increased incrementally by addition of more adjacent carriers. In addition, no bandwidth buffers are needed between transmit bandwidths of separate transmitters as long as orthogonality can be maintained between all the carriers.[2, 161-163; 8; 9] Physical Implementation Since OFDM is carried out in the digital domain, there are many ways it can be implemented. Some options are provided in the following list. Each of these options should be viable given current technology: ASIC (Application Specific Integrated Circuit) ASICs are the fastest, smallest, and lowest power way to implement OFDM Cannot change the ASIC after it is built without designing a new chip General-purpose Microprocessor or MicroController PowerPC 7400 or other processor capable of fast vector operations Highly programmable Needs memory and other peripheral chips Uses the most power and space, and would be the slowest Field-Programmable Gate Array (FPGA) An FPGA combines the speed, power, and density attributes of an ASIC with the programmability of a general purpose processor. An FPGA could be reprogrammed for new functions by a base station to meet future (currently unknown requirements).This should be the best choice.[9] OFDM uses in DVB (Digital Video Broadcasting) DVB (Digital Video Broadcast) is a set of standards for the digital transmission of video and audio streams, and also data transmission. The DVB standards are maintained by the DVB Project, which is an industry-led consortium of over 260 broadcasters, manufacturers, network operators, software developers, regulatory bodies and others in over 35 countries. DVB has been implemented over satellite (DVB-S, DVB-S2), cable (DVB-C), terrestrial broadcasting (DVB-T), and handheld terminals (DVB-H). the DVB standard following the logical progression of signal processing steps, as well as source and channel coding, COFDM modulation, MPEG compression and multiplexing methods, conditional access and set-top box Technology. In this project is presented an investigation of two OFDM based DVB standards, DVB-T and DVB-H. DVB-T (Digital Video Broadcasting Terrestrial) The first Terrestrial Digital Video Broadcasting pilot transmissions were started in the late 90s, and the first commercial system was established in Great Britain. In the next few years the digital broadcasting system has been set up in many countries, and the boom of the digital terrestrial transmission is estimated in the next few years, while the analogue transmission will be cancelled within about 15 years. The greatest advantage of the digital system is the effective use of the frequency spectrum and its lower radiated power in comparison with the analogue transmission, while the covered area remains the same. Another key feature is the possibility of designing a so-called Single Frequency Network (SFN), which means that the neighboring broadcast stations use the same frequency and the adjacent signals dont get interfered. The digital system transmits a data stream, which means that not only television signals but data communication (e.g. Internet service) may be used according to the demands. The data stream consists of an MPEG-2 bit stream, which means a compression is used, enabling the transfer of even 4 or 5 television via the standard 8 MHz wide TV channel. For the viewer, the main advantages are the perfect, noise-free picture, CD quality sound, and easier handling, as well as services like Super Teletext, Electronic Programme Guide, interactivity and mobility.[11, 251-253] Modulation technique in DVB-T The DVB-T Orthogonal Frequency Division Multiplexing (OFDM) modulation system uses multi-carrier transmission. There are 2 modes, the so-called 2k and 8k modes, using 1705 and 6817 carriers respectively, with each carrier modulated separately and transmitted in the 8 MHz TV channel. The common modulation for the carriers is typically QPSK, 16-QAM or 64-QAM. Each signal can be divided into two, so-called „In Phase (I) and „Quadrature Phase components, being a 90Â ° phase shift between them. The constellation diagram and the bit allocation is shown in bellow 16-QAM constellation diagram and bit allocation [6] This modulation can be demonstrated in the constellation diagram, where the 2 axes represent the 2 components (I and Q). In case of using 16-QAM modulation, the number of states is 16, so 1 symbol represents 4 bits. [11, 255; 6; 14] Bir errors If we simulate all the carriers in the constellation diagram we get not just 1 discrete point, but many points, forming a „cloud and representing each state. In case of additive noise the „cloud gets bigger and the receiver may decide incorrectly, resulting in bit errors. Figure 2 shows the measured constellation diagram without and with additive noise. Measured 16-QAM constellation diagram a) without additive noise b) with additive noise [6] To ensure perfect picture quality, the DVB-T system uses a 2 level error correction (Reed-Solomon and Viterbi). This corrects the bad bits at an even 10-4 Bit Error Rate (BER) and enables error-free data transmission. [13, 32-36] The multi-carrier structure The structure of carriers can be illustrated also in the function of time (Figure 20). The horizontal axis is the frequency and the vertical axis is the time. The 8 MHz channel consists of many carriers, placed 4462 Hz or 1116 Hz far from each other according to the modulation mode (2k or 8k). Structure of OFDM carriers [13] There are some reserved, so-called Transmission Parameter Signalling (TPS) carriers that do not transfer payload, just provide transmission mode information for the receiver, so the total number of useful carriers is 1512 and 6048 respectively in the two transmission modes, and the resultant bit rate is between 4,97 and 31,66 Mbit/s, depending on the modulation (QPSK, 16-QAM or 64-QAM), the transmission mode (2k or 8k), the Code Rate (CR) used for error correction and the selected Guard Interval (GI). This guard interval means that there is a small time gap between each symbol, so the transmission is not continuous. This guarding time enables perfect reception by eliminating the errors caused by multipath propagation.[4, 79-90; 13] Frequency spectrum In 2k mode, 1705 carriers are modulated in the 8 MHz TV channel, so each carrier is 4462 Hz far from its neighbor, while in 8k mode this distance is 1116 Hz. In digital broadcasting, there are no vision and sound carriers, so the power for each carrier is the same. This mean

Buddhism Essay -- essays research papers

Buddhism Buddhism is a religion founded by an ex-Prince Siddhartha Gaumata. Gaumata was a prince who was brought up in a perfect surrounding. When the prince left the palace he saw all the poverty. At the age of twenty nine, the prince left his wife and his infant son to meditate and practice Yoga to find peace and enlightenment. Gaumata was meditating for a long time when finally while he was sitting under a Bo tree he had attained the enlightenment he was looking for. It is for this reason he got the name Buddha, meaning the enlightened one. Buddha became a traveling teacher and taught everyone his discovery. Buddha did not write any of his lessons down. He taught about the Four Noble Truths, (1) life is suffering, (2) all suffering is caused by ignorance, (3) Ending ignorance will end suffering, and (4) The path to the destruction of suffering is the Noble Eightfold Path. The Eightfold Path consists of (1) Knowledge of the truth, (2) the intention to resist evil, (3) not saying anything that will hurt someone else, (4) respecting life, (5) having a job that doesn't injure anyone, (6) striving free one's mind of evil, (7) controlling one's feelings, and (8) concentrating properly. Buddha preached that the life was a continuing cycle of death and rebirth. The well-being of oneself was determined on your behavior in your previous life. Buddha said that by ridding oneself of worldly things he would be in nirvana, peace and happiness. After Buddha's death, his followers coll... Buddhism Essay -- essays research papers Buddhism Buddhism is a religion founded by an ex-Prince Siddhartha Gaumata. Gaumata was a prince who was brought up in a perfect surrounding. When the prince left the palace he saw all the poverty. At the age of twenty nine, the prince left his wife and his infant son to meditate and practice Yoga to find peace and enlightenment. Gaumata was meditating for a long time when finally while he was sitting under a Bo tree he had attained the enlightenment he was looking for. It is for this reason he got the name Buddha, meaning the enlightened one. Buddha became a traveling teacher and taught everyone his discovery. Buddha did not write any of his lessons down. He taught about the Four Noble Truths, (1) life is suffering, (2) all suffering is caused by ignorance, (3) Ending ignorance will end suffering, and (4) The path to the destruction of suffering is the Noble Eightfold Path. The Eightfold Path consists of (1) Knowledge of the truth, (2) the intention to resist evil, (3) not saying anything that will hurt someone else, (4) respecting life, (5) having a job that doesn't injure anyone, (6) striving free one's mind of evil, (7) controlling one's feelings, and (8) concentrating properly. Buddha preached that the life was a continuing cycle of death and rebirth. The well-being of oneself was determined on your behavior in your previous life. Buddha said that by ridding oneself of worldly things he would be in nirvana, peace and happiness. After Buddha's death, his followers coll...

Nosrdstrom Case Study Essay

1. The regional Manager of Human resources suggests that you start using a personality assessment too, such as the MBTI, in hiring new employees or your store. What are the benefits of this approach and what are the drawbacks. Now a days good service have become the most important value that a company no matter the industry need to have, therefore the need of employees who really enact it in their daily work is really important and it is in this value where personality plays and enormous part; personality is that thing that define who you are and how you understand the world, they way you act in an specific situation will completely depend on your personality which is constantly shaping depending on the experiences you have during your life time. Being this said an assessment tool, as an MBTI will help you foresee how a person would perform in a specific job with some specific needs and functions regardless of their studies. Note that sometimes this approach might mislead into assumptions of someone’s personality because of how it is perceived, the way we avoid the common errors of perception as first impression error, selective perception, stereotypes among others will succeed or disorientate the approach and will end up with no correct personality description which will mislead you into wrong conclusions. 2. Can a friendly, customer-oriented attitude be developed in person? Can Nordstrom â€Å"train† employees to prioritize making customer happy, or it is purely a matter of personality? Yes it can be developed in a person, but it would depend on its personality how this skill will shine and if this value will be enacted. Something like service, which is customer-oriented attitude, will depend on how this person  understand the world, how he communicate and what are his preferences. Being this said, it is not something that depends whether on the training or in the personality, there has to be a smooth connection between both. Nordstrom for example does an incredible work by hiring people which personality allows them to perform great on their customer-oriented service, a skill they train into each of their employees and due to their personality it is easily adapted and enacted since it is felt natural. 3. Describe the ideal Nordstrom salesperson in terms of the personality traits that are involved in core self-evaluation (CSE). Warmhearted, conscientious, and cooperative. Wants harmony in the environment, works with determination to establish it. Likes to work with others to complete tasks accurately and on time. Loyal , follows through even in small matters. Notices what others need in their day-to-day lives and tries to provide it. Wants to be appreciated for who he or she is and for his or her contribution.

Online MBA †Making School Convenient, Part I Essay Example

Online MBA – Making School Convenient, Part I Essay Example Online MBA – Making School Convenient, Part I Essay Online MBA – Making School Convenient, Part I Essay Any working mother will attest to the juggling act that happens on a daily basis. There is the alarm going off seemingly seconds after you close your eyes, the breakfasts to make, the lunches to pack, the homework to check, the papers to sign, the beds to make, the house to clean, the laundry to do, the shopping run to make, the dinner to plan, the appointments to schedule, the after school activities to attend, and – oh yeah – there’s your full time job. As if you didn’t already have one. This is a lot to manage for anyone under any circumstances but when you throw the potential of school into the mix it gets a whole lot more complicated. I was one of these working mothers and while I was lucky enough to have the help of a very hands-on husband he works long hours as well and often we are like ships passing in the night. I had the responsibilities of my job during the day and the responsibilities of home and family in my additional waking hours. There seemed to be little if any time for myself but that was exactly what I needed to carve out if I was going to have any hope of getting my degree. Education has always been important to me but now more than ever because of the competitive and dwindling job market. I had an undergraduate business degree and a good job but I had always wanted to pursue my masters. This would have been impossible in years past simply because there was no way I was ever going to find the time in my day to commute to school and sit in class. The logistics just didn’t work. But now, with the potential of working through an online MBA program school could finally be a convenience I could a fford. More to come†¦

Book Review on Demonic Possession on Trial

Book Review on Demonic Possession on Trial Sample book review on Demonic Possession on Trial: Demonic Possession on Trial by William W. Coventry was written based on the author’s thesis to earn his Master of Arts in History from the University of Vermont. The book’s purpose is to examine and explore certain witch-craft cases that took place before the Salem witch trials occurred in order to identify the behaviors and ideas that shaped them. It was unclear from reading the book what the author’s views of the cases were; although, he seemed to show sympathy towards the supposed witch’s persecution. His writing was unbiased and covered all aspects of the trials and gave possible reasons for why the women and men seemed to be possessed by â€Å"demons†. He discussed the possibility of medical concerns, jealousy, and revenge as reasons why these people seemed to be possessed. He covered each possibility with equal representation. Coventry discussed how â€Å"superstitious and frightened townspeople turned against one another† (Coventry 67) and also discussed how ‘power hungry clergy promoted fear to maintain their fading power† (Coventry 69). I believe that he succeeded in his purpose to connect the trials that occurred in England to those that happened in Salem, Massachusetts. Although, he seemed to make this connection it was hard to follow. I had to re-read certain parts over a few times. Maybe it was because the subject covered wasn’t to my interest or because of the wording, but it was hard for me to read this book and enjoy it. This book did not relate to any past American history courses I took but instead was a lesson in itself. I knew very little about the witch trials of the 1500’s and 1600’s. I found it surprising that the author went into little depth about the reasons for why the witch trials took place and how witch craft impacted history. Coventry only stated that religion, politics, and socio-economics led to the superstition of possession of the people of England and Salem. Coventry’s book expanded my understanding of the American experience in Salem by including excerpts from journals of those who were involved in the witch trials. The subject of the book was covered well, but as I stated before, it was difficult for me to follow. The author described each case thoroughly including all aspects of the cases and including journal entries to help prove his points. The book was organized well; beginning with the seven trials that took place in England and connecting them to the Salem trials in the last chapter. He included an introduction and also a conclusion, which made the book seem more like an essay than a book, but it was organized well. I found this book to be very interesting; although, sometimes hard to follow because there was a lot of technical terms having to do with possession and also medical terms I was not familiar with. I chose this book because I wanted to learn more about the trials and the people involved in them, but I was sorry to find that the book had more to do with politics and religion rather than stories. I would not recommend this book to another student unless they were very interested in the witch trials of this time. It is not a book that I would consider reading for fun. It took some time to understand exactly what the author was talking about and it wasn’t a very enthralling book. William W. Coventry is not only an author but a song writer as well. He has written and recorded over 100 songs and also has published a book of his lyrics called Myth of Desire. He received his BA in history from Gettysburg College and his MA in history from the University of Vermont.

Work-Life balance in Emirates Group Essay Example | Topics and Well Written Essays - 3000 words

Work-Life balance in Emirates Group - Essay Example This implies a point of equipoise or stability between two equally demanding things – in this case, work life and family life. People have a natural inclination to seek challenge and achievement as much as the desire to enjoy family relationships and the leisurely company of other people they have an affinity for. WLB is now considered as one of the most important qualities of the workplace, second only to the pay rate, because the physical and psychological stability of workers and employees directly impact on the performance of business firms. The usefulness of WLB in enhancing the operations of firms has been the topic of many academic researches, with varying outcomes. WLB has been known to impact positively on workers’ levels of job satisfaction and morale, reduce stress in both work and family life, enhanced organisational efficiency and effectiveness, and reduction in problems experienced in both areas (Kumar & Chakraborty, 2013). As beneficial as WLB sounds, the practice, while gaining legitimacy as a general principle, has received less than enthusiastic response at the execution level. WLB has not been effectively implemented in many organisations; the causes were determined in a survey conducted by Kumar & Chakraborty (2013), some of which are as follows: Negative or indifferent attitude on the part of top management Lack of faith of supervisors in the effectiveness of WLB benefits Uncertainty and reluctance among employees in adopting WLB in their work schedules Stringent work schedules Dictatorial behaviour of supervisors and top management, and their refusal to plan out flexible work schedules Unavailability and inaccessibility of WLB tools and techniques for workers to implement flexible work schedules. Unsupportive organisational culture for the implementation of WLB Bureaucratic procedures and delay in the formulation and execution of WLB policies and practices. Poor structural framework of the planned WLB programme Inconsistency in infrequency of interaction between management and workers in order to assimilate WLB as a transformative element in organisational life. The foregoing enumeration of impediments to what should be an effortless adoption of WLB is evident in many companies, and will likely continue to pose obstacles to its implementation. According to Smith (2010), however, each succeeding generation of workers tend to come to a greater understanding and acceptance of WLB, thus as they advance in the organization into the supervisory and managerial levels it is expected that the attitude of management towards WLB will also eventually change. So far, what has not appeared to be evident to management is the strategic usefulness of WLB as a competitive advantage, in terms of improved quality of work, improved job performance, ethical decision-making and long-term job satisfaction (Smith, 2010). Four areas for flexible work or leave arrangements Industrial Relations Victoria (IRV), a government sub-uni t under the Department of Innovation, Industry and Regional Development, is tasked with monitoring industrial relations in the State’s public and private sectors, and with supporting innovations to address the increasingly competitive business environments without engendering additional industrial (IRV, 2013). According to the IRV, a compilation of the research of several government agencies have identified 27 model family friendly clauses that were directly included in various collective agreements. The 27 clauses (which represented the best practices in the industry) may be classified into four based on their nature and subject. They are as follows Services – This refers to the provision of service options by the employer organisation for the

The Fukushima Daiichi disaster and the future implications for Research Paper

The Fukushima Daiichi disaster and the future implications for building new nuclear power plants in the United States - Research Paper Example The calamity was observed to have taken place in the eastern coast, Tohoku in Japan. The severe tremors of the quake were experienced at Fukushima as well (American Nuclear Society, 2012). The above mentioned catastrophe was later found to have significantly affected the ‘nuclear power station’ or rather the nuclear plant that is situated at Fukushima Daiichi in Japan. This disaster was believed to have triggered the most far-reaching ejection of radioactivity in contrast to the Chernobyl mishap that took place in 1986. This particular radioactivity release was considered to be even shoddier than the case or disaster of Three Mile Island that took place in 1979 in the United States. However, the occurrence of Fukushima Daiichi was considered to differ from the stated incidents of Chernobyl and Three Mile Island as the devastation that occurred at Fukushima was learnt to be triggered owing to natural tragedies which was a massive earthquake chased by tsunami. The discharg e of the radioactive gases was regarded as a consequence of the natural disaster rather than any malfunction with regard to the equipments and even ruled out any chances of human faults. The tsunami was measured to have ruptured the systems that helped in providing backup power and which were required for the reason of cooling down the reactors that were present in the definite plant. The breakdowns of the backup systems as a result made a large number of those reactors go through hydrogen explosions, fuel melting and ultimately radioactive releases (Holt, Campbell, & Nikitin, 2012). The paper will intend to focus on the present situation of the mishap that occurred at Fukushima Daiichi along with providing an insight into the various policies or stands taken by the US after this incident. The Accident at Fukushima Daiichi in Japan The earthquake that took place in March, 2011 in the eastern coast of the island Honshu in Japan resulted in initiating a mechanical shutdown of around e leven nuclear plants out of fifty five. Majority of the shutdowns were found to have carried on without any kind of further events. However, the Fukushima and the Onagwa nuclear plants were found to be the ones that were closely located towards the epicenter owing to which severe damages were suffered by those plants. The plant at Fukushima Daiichi, as a result of the earthquake, accompanied with the tsunami experienced hydrogen outbursts and grave damages in relation to nuclear fuel which triggered the discharge of a noteworthy quantity of radioactive elements in the surrounding environment (Holt, Campbell, & Nikitin, 2012). The contamination of the surrounding environment, with the radioactive elements that originated from the plants, compelled the moving out of communities from the adjacent or the neighboring areas till 25 miles. The forceful move out of the communities resulted in disturbing the regular life of around 100,000 residents, majority of whom were believed to remain b anned from accessing their respective homes for an indefinite period. The evacuation activities made in this context are considered to have checked the degree of radiation exposure with regard to the concerned population from surpassing the Japanese authoritarian boundaries in majority of the incidences. However, the consequences of the exposure to the radioactive gases with regard to the residents were measured not to be quite grave. Future deaths as well as