Decision feedback equalization in OFDM with long delay spreads

OFDM:ään perustuvat yhden taajuuden verkot (SFN), joita käytetään DVB-T yleisradiolähetyksissä tarjoavat monia etuja. Niistä on tullut standardiratkaisu digitaalisten televisiolähetysten tuottamiseen Euroopassa. Vastaanottimessa yhtäaikaiset lähetykset monista SFN:n monista lähettimistä näyttävät kanavalta, jolla on pitkä viivehaje. Viivästettyinä vastaanotettavat signaalit lisäävät interferenssiä vastaanotossa, ja osaltaan lisäävät vastaanotossa tapahtuiva virheitä. Tässä työssä tarkastellaan mahdollisuutta parantaa vastaanottimen toimintaa pitkän viivehajeen kanavissa käyttäen päätöstakaisinkytkentää (DFE). Ehdotettu DFE-vastaanotin sisältää rinnakkaisen interferenssinpoistajan (PIC) feedforward-suotimenaan. Tämä yhdistelmä parantaa symbolin vastaanottoa ilman että vastaanottimen kompleksisuus lisääntyy kohtuuttomasti. Työssä tutkitaan ehdotetun DFE-vastaanottimen toimintaa simulaatioin, ja verrataan sen suorituskykyä tavanomaiseen OFDM-vastaanottimeen. SFN-skenaarioita mallinnetaan monitappisilla Rayleigh-häipyvillä kanavilla, joilla on pitkä viivehaje. Vartailut suoritetaan simulaattorissa joka on kehitetty käyttäen MATLAB-kieltä.OFDM-based Single Frequency Networks (SFN) used in DVB-T broadcasting offer many advantages and have become the standard solution being adopted in Europe. However, at the receiver, the simultaneous data transmission from the multiple transmitters in an SFN is interpreted as a channel with a long delay spread. The multiple signals being received at delayed intervals cause an increase in interference components that cause errors in symbol recovery. In order to recover from performance degradation inherent in such channels with long delay spreads, this thesis discusses a receiver design based on the implementation of a Decision Feed-back Equalizer (DFE). The proposed DFE receiver incorporates a Parallel Interference Canceller (PIC) as its feed-forward filter. This simple combination enables better symbol recovery while maintaining a simple receiver design. In this thesis the simulation performance of the proposed DFE receiver is investigated in comparison to the conventional OFDM receiver. In order to implement SFN scenarios, multipath Rayleigh fading channels with long delay spreads are selected as the wireless communication medium. The evaluation is done in a simulator developed in MATLAB

What Does Matter? Liquidity or Profitability: A Case of Sugar Industry in Pakistan

Keeping in mind the Keynes of the Pakistan's Sugar Industry in its overall economic well-being, the current work objects to examine the liquidity-profitability trade off in Sugar Industry of Pakistan. Secondary data of the non-financial companies which are listed on KSE is used for sugar industry over the last five years. Present study used different analytical tools like Reliability Analysis, Descriptive Statistics, Multiple Regression Analysis, Correlation and tests of significance to test the causal linkage in liquidity and profitability. Results of regression analysis showed that, hypothesis one is rejected because liquidity generates positive impact on ROA and found significant at 1% level. Hypothesis two of the current study is rejected because liquidity causes positive impact on ROE and found significant at 1% level. According to regression analysis, hypothesis three is also rejected because liquidity influences ROCE positively and found significant at 1% level. Results of correlation analysis discovered that liquidity of Sugar Mills is positively and significantly correlated with all measures of profitability i.e. ROA, ROE and ROCE. Findings of current research suggest managers to come out of the dilemma with respect to liquidity and profitability tradeoff. It is further concluded that managers can increase the firm's profitability and shareholder's value if they invest effectively and efficiently in liquid assets. Finally this study's results make it important for the reason that it is one of the fewer researches going in contrast to the existing knowledge base. Keywords: Liquidity, Profitability, Trade-off, Sugar Industry of Pakistan JEL Classification: G3

Bays International Private Limited: Evolving Through Market Dynamics

Bays International was incorporated in 1996. Over the years it faced numerous challenges including: high employee turnover (particulary saleforce), limited expansion capabilities, low penetration in semi-urban markets, high operating expenses like rentals, increasing duties (on luxury products), low cash-flows, low budgets for advertising and marketing as compared to competitors, less awareness amongst consumers, volatile consumer preferences (especially by millennial), weak brands’ loyalties, counterfeits/fake products, smuggling and infiltration from grey channels, high number of foreign and local chains entering the market, price war especially with local chains, and uncertain political situation. Four interviews were conducted from management and two interviews from ex employees. Moreover, a lot of open access documents of the company were reviewed. Pertinent literature reveiew also revealed interesting insights about emerging consumer trends and cosmetic industry along with interviews of some marketing directors of leading global brands. The Bays leadership believes that key parameters are improving over time. The case covers how the company maneuvered itself since its inception and launched numerous other brands targeted towards different segments of the society, in order to steer towards growth in changing internal and external environment. The case is based on a scenario when there is yet another increase of taxes by the government in 2019 and presents troublesome situations to branding cum marketing strategy for the company to consider

Adsorptive defluoridation from aqueous solution using a novel blend of eggshell powder and chitosan nanofibers

Groundwater mostly contains many impurities thus can not be consumed as drinking water directly. The acceptable limit of fluoride in drinking water is 0.5–1.5 mg l ^−1 recommended by World Health Organization (WHO). In this research, a novel nanofiber hybrid; based on Chitosan (CTS) and Eggshell (EGG) was prepared via electrospinning technique and investigated for deflouridation from aqueous solution. SEM images reveal bead-free, smooth morphology and the FTIR confirmed the presence of chitosan and egg within the novel nanofiber blend. The defluoridation efficiency was assessed by varying the different parameters like pH, mass of nanofibers, contact time and initial concentration for adsorption. Studies revealed that CTS/EGG nanofibers hybrid shows incredible adsorption efficiency of 86%. Furthermore, isotherm studies show that the Langmuir isotherm model was well fitted for both CTS and CTS/EGG nanofibers

Fabrication and characterization of co-electrospun cellulose/poly (4-methyl-1-pentene) nanofibers with improved tensile properties

In this study, cellulose acetate and poly (4-methyl-1-pentene) (CA/PMP) nanofibers were co-electrospun with a blending ratio of 1:1 and followed by deacetylation treatment to produce cellulose/PMP nanofibers. The physical morphology of nanofibers was characterized by SEM which reveals even and bead-less morphology of nanofibers with an average diameter of 650 nm. FTIR study confirmed the removal of acetyl groups after deacetylation, and x-ray diffraction analysis was performed to analyze the crystalline nature of nanofibers. The calculated crystallinity and crystal size of CA/PMP nanofibers are 82% and 34 Å. The tensile strength study revealed that the combination of both CA and PMP nanofibers with the blending ratio of 1:1 has improved the tensile strength of composite nanofibers. Further, the deacetylation process has also increased the tensile strength. The obtained tensile strength and Young’s modulus are 6.9 MPa and 195 MPa for cellulose/PMP nanofibers which could be a value addition in cellulose-based membranes