Informatics Publishing Limited

Taru Mahajan ¹, Mandeep Kour ²

Affiliations
1 Beant College of Engineering and Technology (BCET) Gurdaspur, Punjab, IN
2 Department of Electronics and Communication Engineering at BCET, Gurdaspur, Punjab, IN

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) spread spectrum technique distributes the data over a large number of carriers that are spaced orthogonally apart at precise frequencies i.e, sub-carriers are able to carry information without interference, which prevents the demodulators from seeing frequencies other than their own. The benefits of OFDM are high spectral efficiency, robustness to channel fading, immunity to impulse interference, capability of handling very strong multi-path and frequency selective fading without having to provide powerful channel equalization. Multi-carrier modulation systems such as OFDM have very high Peak to Average power ratio (PAPR); i.e. they exhibit very high peaks whose power is very large compared to mean power. The different subcarriers may all line up in phase at some instants in time and therefore produce a large peak equal to the sum of the amplitudes of the individual subcarriers. However, with large number of subcarriers, the magnitude of samples of OFDM symbols is approximately Rayleigh distributed and the large peaks occur with extremely low probability. In this paper different techniques for reducing PAPR, such as Partial Transmit Sequence (PTS), Suboptimal PTS, Repeated Clipping and Frequency Domain Filtering techniques and a new technique based on the combination of PTS and Clipping techniques, that gives more reduction in PAPR than PTS technique and less in-band distortion compared to clipping technique, making this technique adaptive for the implementation of low-PAPR OFDM system, are analyzed and simulated in MATLAB.

Keywords

Complementary Cumulative Distribution Function, Clipping, OFDM, and Partial Transmit Sequence, Peak to Average Power Ratio.

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Pawandeep Kour ¹, Neeraj Gupta ¹, Mandeep Kour ¹

Affiliations
1 Division of FST, Main Campus Chatha, SKUAST-J., Jammu (J&K), IN

Abstract

The lemon, Citrus limon (L.), is a species of small evergreen tree in the flowering plant family Rutaceae, native to Asia. Citrus limon belongs to the family Rutaceae, Lemons are very high in vitamin C which protects against various diseases and contributes to a strong immune system. Lemon also contain phytochemicals flavonoids giving it a greater antioxidant boost. They also contain good amount of B-complex vitamins, like folate as well as minerals like calcium, iron, copper and potassium.The tree’s ellipsoidal yellow fruit is used for culinary and non-culinary purposes throughout the world, primarily for its juice, which has both culinary and cleaning uses. The pulp and rind (zest) are also used in cooking and baking. The juice of the lemon is about 5 per cent to 6 per cent citric acid, with a pH of around 2.2, giving it a sour taste. The distinctive sour taste of lemon juice makes it a key ingredient in drinks and foods such as lemonade and lemon meringue pie.

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