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- 저자 : ( Sana Mazahir ) (검색결과 2 건)
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An Adaptive Companding Scheme for Peak-to-average Power Ratio Reduction in OFDM Systems
( Sana Mazahir ),( Shahzad Amin Sheikh ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.12
Orthogonal frequency division multiplexing (OFDM) signals suffer from the problem of high peak-to-average power ratio (PAPR), which complicates the design of analog front-end of the system. Companding is a well-known PAPR reduction technique that involves transforming signal amplitudes using a deterministic function. OFDM signal amplitude, on average, is Rayleigh distributed but the distribution can vary significantly from symbol to symbol, especially when constellation size increases. In this paper, a new adaptive companding scheme is proposed along with its design methodology aiming at optimizing the compander performance by accommodating this variation in its design. This is achieved by designing compander parameters separately for statistically dissimilar symbols in OFDM waveform and making the compander select from these parameters, during run-time, according to the features of input symbols.
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Optimal Design of Piecewise Linear Companding Transforms for PAPR Reduction in OFDM Systems
( Sana Mazahir ),( Shahzad Amin Sheikh ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.1
Orthogonal frequency division multiplexing (OFDM) signals suffer from the problem of large peak-to-average power ratio (PAPR) which complicates the design of the analog front-end of the system. Companding is a well-known PAPR reduction technique that reduces the PAPR by transforming the signal amplitude using a deterministic function. In this paper, a novel piecewise linear companding transform is proposed. The design criteria for the proposed transform is developed by investigating the relationships between the compander and decompander`s profile and parameters with the system`s performance metrics. Using analysis and simulations, we relate the companding parameters with the bit error rate (BER), out-of-band interference (OBI), amount of companding noise, computational complexity and average power. Based on a set of criteria developed thereof, we formulate the design of the proposed transform. The main aim is to preserve the signal`s attributes as much as possible for a predetermined amount of PAPR reduction. Simulations are carried out to evaluate and compare the proposed scheme with the existing companding transforms to demonstrate the enhancement in PAPR, BER and OBI performances.
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