Naga VishnuKanth I

Bio: Naga VishnuKanth I is an academic researcher from Indian Institute of Chemical Technology. The author has contributed to research in topics: Thresholding & Reduction (complexity). The author has an hindex of 1, co-authored 1 publications receiving 18 citations.

A Low Complexity SLM Technique for PAPR Reduction in OFDM Using Riemann Sequence and Thresholding of Power Amplifier

Abstract: Selected Mapping (SLM) technique is one of the promising PAPR reduction techniques for Orthogonal Frequency Division Multiplexing (OFDM). But this reduction technique results in a huge amount of computation complexity which is costly and time consuming. In this paper, Riemann sequences are used as a phase vectors along with the thresholding of the power amplifier(PA). The default index of the phase sequence is used to reduce the computational complexity of SLM technique. The default index of a phase sequence refers to the starting index for the phase vectors in the SLM scheme. This index is derived from the experimentation results. The Matlab simulations show that the complexity has been reduced by 98 percent if the threshold value of PA is around 3.0dB. Index Terms—OFDM, PAPR, Complexity, Riemann Sequence, Error function, Default Index.

Peak to Average Power Ratio (PAPR) reduction in OFDM for a WLAN network using SLM technique

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is a spectrally efficient multicarrier modulation technique for high speed data transmission over multipath fading channels. OFDM modulation schemes offer many advantages for multicarrier transmission at high data rates over time dispersive channels, particularly in mobile applications. One of the main issues of OFDM is high Peak-to-Average Power Ratio (PAPR) of the transmitted signal which adversely affects the complexity of power amplifiers. SeLected Mapping (SLM) technique is one of the promising PAPR reduction techniques for OFDM. This paper analyzes the capability of the existing SLM technique in reducing the effect of Peak-to-Average Power Ratio. The approach is very flexible and works with arbitrary numbers of subcarriers and without restriction on the type of modulation applied in them. The analysis is on a network model designed by WLAN 802.11a standard using MATLAB, a mathematical simulation software tool. As a performance measure for the PAPR reduction, we study the probability that the PAPR of an OFDM data block exceeds a given threshold, which is the Complementary Cumulative Distribution Function (CCDF) of PAPR.

SLM Using Riemann Sequence Combined with DCT Transform for PAPR Reduction in OFDM Communication Systems

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is an efficient method of data transmission f r high speed communication systems. However, the main drawback o f OFDM systems is that, it suffers from the problem of hig h Peak-to-Average Power Ratio (PAPR) which causes inefficient use of the High Power Amplifier and could limit transmission efficiency. OFDM consist of large number of independent subcarriers, as a resul t of which the amplitude of such a signal can have high peak value s. In this paper, we propose an effective reduction scheme that combi nes DCT and SLM techniques. The scheme is composed of the DCT f ollowed by the SLM using the Riemann matrix to obtain phase se quences for the SLM technique. The simulation results show PAPR can be greatly reduced by applying the proposed scheme. In compari son with OFDM, while OFDM had high values of PAPR –about 10. 4dB our proposed method achieved about 4.7dB reduction of t he PAPR with low complexities computation. This approach also av oids randomness in phase sequence selection, which makes it simpler to decode at the receiver. As an added benefit, the m atrices can be generated at the receiver end to obtain the data si gnal and hence it is not required to transmit side information (SI). Keywords—DCT transform, OFDM, PAPR, Riemann matrix, SLM.

Receiver Design for Nonlinearly Distorted OFDM Signals: Applications in Radio-over-Fiber Systems

Abstract: Tese de doutoramento. Engenharia Electrotecnica e de Computadores. Universidade do Porto. Faculdade de Engenharia. 2011

A computationally efficient selected mapping technique for reducing PAPR of OFDM

Abstract: In orthogonal frequency division multiplexing (OFDM) system, high value of peak-to-average power ratio (PAPR) is an operational problem that may cause non-linear distortion resulting in high bit error rate. Selected mapping (SLM) is a well known technique that shows good PAPR reduction capability but inflicts added computational overhead. In this paper, using Riemann sequence based SLM method, we applied reverse searching technique to find out low PAPR yielding phase sequences with significant reduction in computational complexity. Additionally, we explored side-information free transmission that achieves higher throughput but sacrifices PAPR reduction. Finally, to overcome this loss in PAPR reduction, we proposed application of Square-rooting companding technique over the output OFDM transmitted signal. Simulation results show that the proposed method is able to compensate the sacrifice in PAPR and achieved PAPR reduction of 8.9 dB with very low computational overhead.