Peak-cancelling Signal Research Articles

Peak Cancellation Signal Generation Considering Variance in Signal Power among Transmitter Antennas in PAPR Reduction Method Using Null Space in MIMO Channel for MIMO-OFDM Signals

Peak Cancellation Signal Generation Considering Variance in Signal Power among Transmitter Antennas in PAPR Reduction Method Using Null Space in MIMO Channel for MIMO-OFDM Signals

Efficient Parallel PAPR Reduction Method Using Null-Constrained Peak Cancellation Signal for Massive MIMO-OFDM Systems

Efficient Parallel PAPR Reduction Method Using Null-Constrained Peak Cancellation Signal for Massive MIMO-OFDM Systems

Novel Tone Reservation Method for DFT-s-OFDM

In this letter, a novel guard-tone reservation (GTR) method is proposed to reduce the peak-to-average power ratio (PAPR) of discrete Fourier transform-spread-orthogonal frequency-division multiplexing (DFT-s-OFDM) waveform. Unlike existing PAPR reduction methods, the proposed GTR operates directly in the data symbol domain, estimating the peaks through the relations between the data symbols, while the corresponding peak-cancellation signal (PCS) is efficiently embedded into the waveform processing. Furthermore, the PCS is generated by exploiting only the guard-band tones, leaving thus the inband data tones undistorted. The performance of the method is evaluated in 5G New Radio (NR) uplink context including also realistic measured power amplifier (PA) characteristics. The obtained results show that significant PAPR reduction and corresponding PA output power gains can be obtained while the computational complexity is shown to be low.

PAPR Reduction in MIMO-OFDM Systems Using Low- Complexity Additive Signal Mixing

A MIMO-OFDM wireless communication technique possesses several advantages accrued from combining MIMO and OFDM techniques such as increased channel capacity and improved BER performance. This has made the technique very amiable to current and future generations of communication systems for high data-rate transmission. However, the technique also inherits the high PAPR problem associated with OFDM signals—a problem still requiring a practical solution. This work proposes a PAPR reduction algorithm for solving the problem of high PAPR in MIMO-OFDM systems. The proposed method uses a low-complexity signal mixing concept to combine the original transmit signal and a generated peak-cancelling signal. The computational complexity of the proposed method is O(M) , which is very much less than O(N log2 N) of the FFT algorithms. This is because M, which denotes the number of nonzero peakcancelling samples, is much less than N, the FFT window size. The proposed method was found to achieve high PAPR reductions while utilizing only a few nonzero peak-cancelling samples and it does not significantly change the power of the transmitted signal. For example, with M=5% of 256-point IFFT samples, corresponding to a data rate loss of 4.8%, a large PAPR reduction of 5.9 dB could be achieved at a small power loss of 0.09 dB. Compared with other methods proposed in literature, the proposed method was found to outperform them in terms of PAPR reductions and BER performance.

Performance Analysis of OFDM With Peak Cancellation Under EVM and ACLR Restrictions

This paper presents performance analysis of an adaptive peak cancellation method to reduce the high peak-toaverage power ratio (PAPR) for OFDM systems, while keeping the out-of-band (OoB) power leakage as well as an in-band distortion power below the pre-determined level. In this work, the increase of adjacent leakage power ratio (ACLR) and error vector magnitude (EVM) are estimated recursively using the detected peak amplitude. We present analytical framework for OFDM-based systems with theoretical bit error rate (BER) representations and detection of optimum peak threshold based on predefined EVM and ACLR requirements. Moreover, the optimum peak detection threshold is selected based on the oretical design to maintain the predefined distortion level. Thus, their degradations are automatically restricted below the pre-defined levels which correspond to target OoB radiation. We also discuss the practical design of peak-cancellation (PC) signal with target OoB radiation and in-band distortion through optimizing the windowing size of the PC signal. Numerical results show the improvements with respect to both achievable bit error rate (BER) and PAPR with the PC method in eigen-beam space division multiplexing (E-SDM) systems under restriction of OoB power radiation. It can also be seen that the theoretical BER shows good agreements with simulation results.

Novel Peak-to-Average Power Ratio Reduction Methods for OFDM/OQAM Systems

The tone reservation method is one of the most effective pre-distortion methods for peak-to-average power ratio reduction in orthogonal frequency division multiplexing (OFDM) systems. Its direct application to OFDM systems with offset quadrature amplitude modulation (OQAM) is, however, not effective. In this paper, two novel TR-based methods are proposed, specifically designed for OFDM/OQAM systems by taking into consideration the overlapping nature of OQAM signals. These two methods have different approaches to the generation of the peak-cancelling signal. The first one (overlapped scaling tone reservation) generates the peak-cancelling signal using a least squares approximation algorithm with possible adjacent symbol overlap; the second one (multi-kernel tone reservation) generates the peak-cancelling signal by using multiple impulse-like time domain kernels. It is shown by simulation that, when used in OFDM/OQAM systems, the proposed methods can provide better performance than the direct application of the existing controlled clipping tone reservation method, and even outperform the multi-block tone reservation method.

Efficient tone reservation peak‐to‐average power ratio reduction system with optimal clipping for orthogonal frequency division multiplexing systems

In this study, the authors propose an efficient peak-to-average power ratio (PAPR) reduction system for OFDM transmission based on tone reservation (TR). In this system, a novel cost function to jointly optimise the clipping level and the peak-cancelling signal is proposed. The obtained optimal clipping level can not only render the clipping noise to be well approximated by the reserved tones, but also be small enough to deeply suppress the peaks. In addition, a new cyclic method to optimise the peak-cancelling signal and the clipping level is presented with the insight that when optimising the reserved tone values, the time-domain signal to be thresholded itself depends on the peak-cancelling signal instead of being constant, as assumed by many other methods. Simulation results show that the proposed system significantly improves the PAPR reduction performance over the state-of-the-art clipping-based TR algorithms.

AN EFFICIENT POWER REDUCTION TECHNIQUE IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM USING TONE RESERVATION

In a basic communication system, the data’s are modulated onto a single carrier frequency. The available bandwidth is then totally occupied by each symbol. This kind of system can lead to Inter-Symbol-Interference (ISI) in case of frequency selective fading. The basic idea of Orthogonal Frequency Division Multiplexing (OFDM) is to divide the available spectrum into several orthogonal sub channels so that each narrowband sub channel experiences almost flat fading. In OFDM system, orthogonally placed sub-carriers are used to carry the data from the transmitter end to the receiver end. However, the major challenging issue is to reduce PAPR and Bit Error Rate (BER). The reduction algorithm for OFDM signals is presented in this project using convex optimization technique along with Tone Reservation (TR). Tone reservation uses other unused or reserved tones to design a peak-cancelling signal that lowers the PAR of a transmit OFDM block. Similarly it lowers the bit error rate. In contrast to previous methods, the tone reservation with convex optimization implies a very quick convergence of minimum-PAR and bit error rate solution at a lower computational cost. Also the effects of oversampling at l = 1,2,4,8 on the performance of proposed OFDM system is discussed.

A Selected Peak Based TR Approach for OFDM PAPR Reduction

A high Peak-to-Average Power Ratio (PAPR) can lead to nonlinear distortion and low efficiency in Orthogonal Frequency-Division Multiplexing(OFDM) system. The approach of tone reservation (TR) designs peak-cancelling signal on reserved sub-carriers for peak cancellation and PAPR reduction. Aiming at reducing the computation of TR, this paper presents a new TR approach basing on selected peak. To narrow the search space of peak-cancelling signal, we calculate the maximum peak range of peak-canceling signal according to the relationship between peak value and threshold of power amplifier. Further, we propose the strategy to search the optimal peak-canceling signal which can eliminate the most of ultra-limit peaks. Simulation results show that the selected peak based TR approach can reduce computation effectively with preferable PAPR reduction.

A Tone Reservation-Based Optical OFDM System for Short-Range IM/DD Transmission

This paper investigates the use of tone reservation for optical orthogonal frequency-division multiplexing (OFDM) transmission in a short-range, intensity-modulated, direct-detected (IM/DD) optical channel. Due to the unipolarity of the IM/DD channel, any asymmetric clipping of the bipolar OFDM signal and associated nonlinear distortion will result in an unfavorable dc power and significant performance penalty. Using a detailed analysis of the clipping distortion, we propose a new framework to enable IM/DD optical OFDM transmission, where certain subchannels are reserved to produce a negative peak cancellation (NPC) signal via a frequency-domain digital filter. This NPC signal guarantees a unipolar OFDM signal, hence eliminating any additional biasing and/or clipping. It also produces no in-band or out-of-and distortions and requires no transmission of any side information. Beneficial tradeoffs are identified that enable an efficient use of both the available power and spectrum.

An Active-Set Approach for OFDM PAR Reduction via Tone Reservation

Common to all orthogonal frequency division multiplexing (OFDM) systems is a large peak-to-average-power ratio (PAR), which can lead to low power efficiency and nonlinear distortion at the transmit power amplifier. Tone reservation uses other unused or reserved tones to design a peak-cancelling signal that lowers the PAR of a transmit OFDM block. In contrast to previous methods, the new active-set method proposed here converges very quickly toward a minimum-PAR solution at a lower computational cost. An efficient real-baseband algorithm is well suited for discrete multitone (DMT) modulation over twisted-pair copper wiring, where some subchannels may have an insufficient SNR to reliably send data. The real PAR problem occurs in the analog signal before the power amplifier, and results focus on this figure of merit. The performance of oversampling before applying PAR reduction is analyzed, and results show that this is necessary to sufficiently handle the analog PAR problem. An extension of the real-baseband technique can be applied to complex-baseband signals to help reduce PAR in wireless and broadcast systems. By sacrificing 11 out of 256 OFDM tones (4.3%) for tone reservation, over 3 dB of analog PAR reduction can be obtained for a wireless system.