An optimal nonlinear companding transform with clipping scheme for universal filtered multicarrier systems

Summary In this article, an exponential companding (EC) scheme, which can reduce PAPR without raising the average output power level, is proposed for universal filtered multi carrier (UFMC) signals. However, EC scheme degrades the BER performance. Therefore, an optimal nonlinear companding transform...

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Bibliographic Details
Published in:International journal of communication systems 2020-11, Vol.33 (16), p.n/a
Main Authors: Chintala, Vijaya Durga, Sundru, Anuradha
Format: Article
Language:English
Subjects:
clipping
Companding
Hybrid systems
PAPR
SSPA
UFMC
WARP
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Summary:Summary In this article, an exponential companding (EC) scheme, which can reduce PAPR without raising the average output power level, is proposed for universal filtered multi carrier (UFMC) signals. However, EC scheme degrades the BER performance. Therefore, an optimal nonlinear companding transform named as “modified exponential companding” (MEC), which can use two companding levels based on a threshold value, is proposed. The proposed MEC scheme shows enhanced PAPR and BER performances than EC scheme. Moreover, the MEC provides more design flexibility and freedom with an unchanged average output power level. Furthermore, a hybrid scheme is also proposed to improve PAPR performance, where clipping operation is employed on MEC signal based on an appropriate clipping threshold. Simulation results illustrate that proposed MEC scheme offers improved system performance with a net gain of 7.22 dB than conventional EC and μ‐law techniques. Besides, the proposed hybrid scheme with clipping ratio 1.3 proffers enhanced PAPR reduction of 8.85 dB and improved net gain of 7.95 dB. Also, the proposed EC, MEC, and hybrid schemes can provide lesser spectrum side‐lobe levels than μ‐law. Finally, the UFMC system with the proposed hybrid scheme is verified by employing wireless open‐access research platform (WARP) as hardware over real‐time channel. An exponential companding (EC) scheme, which reduces PAPR, is proposed for UFMC signals. However, EC scheme degrades the BER performance. Therefore, an optimal modified exponential companding (MEC) and hybrid scheme are proposed. The MEC scheme offers improved system performance with a net gain of 7.22dB than EC and μ‐law techniques. Besides, the proposed hybrid scheme with clipping ratio 1.3 offers a net gain of 7.95dB. Additionally, the proposed optimal hybrid transform is compared with the hybrid advanced rooting companding technique.
ISSN:1074-5351
1099-1131
DOI:10.1002/dac.4587