A Simplified Scheme of Estimation and Cancellation of Companding Noise for Companded Multicarrier Transmission Systems

Nonlinear companding transform is an efficient method to reduce the high peak-to-average power ratio (PAPR) of multicarrier transmission systems. However, the introduced companding noise greatly degrades the bit-error-rate (BER) performance of the companded multicarrier systems. In this paper, a simplified but effective scheme of estimation and cancellation of companding noise for the companded multicarrier transmission system is proposed. By expressing the companded signals as the summation of original signals added with a companding noise component, and subtracting this estimated companding noise from the received signals, the BER performance of the overall system can be significantly improved. Simulation results well confirm the great advantages of the proposed scheme over other conventional decompanding or no decompanding schemes under various situations

PAPR Reduction in OFDM System by using Nonlinear Companding Technique

Non linear companding technique is proposed to reduce the high peak to average power ratio (PAPR) of orthogonal frequency division multiplexing system. Use of companding for peak - to - average - power ratio (PAPR) control is explored for a link involving a non - linear transmit power amplifier with orthogonal frequency division multiplexing (OFDM). This paper analyses the improvement in bit error rate (BER) and overall system performance by employing non linear companding technique for PAPR reduction in digital video broadcasting (DVB - T) system

Analysis of Improved µ-Law Companding Technique for OFDM Systems

YesHigh Peak-to-Average-Power Ratio (PAPR) of transmitted signals is a common problem in broadband telecommunication systems using an orthogonal frequency division multiplexing (OFDM) modulation scheme, as it increases transmitter power consumption. In consumer applications where it impacts mobile terminal battery life and infrastructure running costs, this is a major factor in customer satisfaction. Companding techniques have been recently used to alleviate this high PAPR. In this paper, a companding scheme with an offset, amidst two nonlinear companding levels, is proposed to achieve better PAPR reduction while maintaining an acceptable bit error rate (BER) level, resulting in electronic products of higher power efficiency. Study cases have included the effect of companding on the OFDM signal with and without an offset. A novel closed-form approximation for the BER of the proposed companding scheme is also presented, and its accuracy is compared against simulation results. A method for choosing best companding parameters is presented based on contour plots. Practical emulation of a real time OFDM-based system has been implemented and evaluated using a Field Programmable Gate Array (FPGA)

A New PAPR reduction Technique based on Precoding and Gamma Companding Technique for OFDM system

Multi-carrier modulation is less sensitive to time dispersion of the channel. In particular, Orthogonal Frequency Division Multiplexing (OFDM) has gained more attention in the last decade owing to rising power of digital signal processing. In spite of the several difficulties that entails during implementation of OFDM system, one of the major drawbacks in OFDM is high peak to average power ratio. Hence it is mandate to research on the characteristics of the PAPR in association with its distribution and reduction in OFDM systems. Myriad of techniques were introduced to reduce Bit error rate and PAPR. Amidst these techniques, precoding gives best solution for reducing PAPR. But in this technique, more null subcarriers are incorporated which leads to out-of-band power emission and in turn reduces the transmission rate. In order to minimize OOB power emission, we combine precoding in frequency domain and gamma companding technique in time domain. The gamma compander promotes OOB power emission. Simulation results reveals a trade off between OOB power emission and PAPR reduction

Enhancement of Analytical OBR (Out of Band Radiation) and BER Calculation for Digital Au-dio-Video Broadcasting in Companded OFDM System using Non-Symmetric QAM/QPSK Tecniques

Companding transforms useful under assumption of infinite bandwidth. Under band limited conditions OBR parameter filters out. So bandwidth is a factor that decides the filter-ing out OBR on the performance of companded OFDM sys-tems. As a result filtering becomes essential under band lim-ited conditions in turn this does deteriorate the system per-formance significantly. In this paper method proposed to overcome the performance degradation. Method called non symmetric scheme based on the use of curve fitting method to find out a suitable polynomial to be used for decom-panding at the receiver. This method indeed improves the performance in comparison to existing symmetric methods when filtering is necessary for band limited conditions

A simple nonlinear companding transform for nonlinear compensation of direct-detection optical OFDM systems

In direct-detection OFDM systems, the nonlinear effects caused by optical modulation and fiber transmission can degrade the system performance severely. In this study, we propose a new nonlinear companding transform to improve the performance of direct detection optical OFDM transmission systems. The demonstration is realized by Monte-Carlo simulation of the intensity modulation and direct-detection DCO-OFDM optical transmission system at 40 Gbps over a 80 km of standard single mode fiber link. The influence of the companding parameters on the performance of system in different nonlinear transmission conditions has been investigated via simulation