A Novel Peak-to-Average Power Ratio Reduction for 5G Advanced Waveforms

Orthogonal frequency division multiplexing (OFDM) is the advanced transmission scheme utilized in 4G. Nevertheless, it has several shortcomings like guard band, peak-to-average power ratio (PAPR), high power consumption, incapable to accommodate various other devices (an IOT application). Hence, OFDM cannot be considered in 5G due to the several disadvantages mentioned above. Filter bank multi-carrier (FBMC) is believed to be one of the most promising technologies which can be used in 5G. FBMC and OFDM are multi-carrier system. It is obvious that it agonizes from PAPR which hamper the efficiency of the system. The conventional peak reduction methods utilized in OFDM cannot be used in FBMC due to the overlapping structure of FBMC. In this work, a novel selective mapping (SLM) and partial transmit sequence (PTS) PAPR reduction technique is suggested for FBMC. The proposed techniques are implemented by using an elementary successive optimization technique that upsurge the PAPR performance and ensure the design difficulty is taken low. PAPR and bit error rate (BER) parameters are analyzed and simulated for the proposed and conventional PAPR reduction techniques. The simulation results show that the SLM and PTS accomplished an excellent PAPR reduction up to 2.8 and 4.8 dB as compared to other peak power minimization techniques.

MC-CDMA is a very promising technique for high-bit-rate and high capacity transmission in mobile communications. One disadvantage of multicarrier modulation is the high peak-to-average power ratio (PAPR) that results in nonlinear distortion at a high power amplifier (HPA) and the degradation of BER. Various methods for reducing PAPR have been proposed for OFDM. It is known that the partial transmit sequence (PTS) and the selected mapping (SLM) are effective for OFDM. The PTS has been applied to MC-CDMA and shown that it is effective for reducing the PAPR in MC-CDMA as well. However, the effects of SLM for MC-CDMA have not been clarified. We investigate the effects of SLM for MC-CDMA. We also investigate phase sequences in the SLM that is suitable for reducing the PAPR in MC-CDMA. We show that the SLM is more effective than the PTS at the same amount of side information.

Orthogonal Frequency Division Multiplexing (OFDM) is typically a system used in encoding digital data. It has huge benefits among which primary are high spectral efficiency upon Inter Symbol Interference (ISI) and robustness. It also has some drawbacks, the main hitch in OFDM system is High Peak to Average Power Ratio (PAPR). In order to minimize PAPR, many techniques are available among which some common and efficient are Partial Transmit Sequence (PTS), Selected Mapping (SLM), Coding, Interleaving, Companding, Peak windowing, Peak reduction, Envelope Scaling. Every method has both edge and snag. The simplest is clipping. There are also some complex techniques like PTS, SLM. In this paper the proposed method is a hybrid combination of Repeated Frequency Domain Filtering and Clipping (RFDFC) and Absolute Exponential Companding (AEC). This method not only bring PAPR to 3.5 dB as compared to 10.5 dB in original, but is also easy to implement.

In wireless communication, parallel transmission of symbols using multi carriers is applied to achieve high efficiency in terms of throughput and better transmission quality. Orthogonal Frequency Division Multiplexing (OFDM) is one of the techniques for parallel transmission. In multipath environment the performance of orthogonal frequency division multiplexing (OFDM) is improved by introducing some kind of channel coding. Coded OFDM (COFDM) is the new candidate for application such as DAB and DVB-T due to its better performance in fading environment. However high peak to average power ratio (PAPR) is a major demerit of OFDM system, it leads to increased complexity of circuit and reduced efficiency of RF amplifier. In this paper our aim is to evaluate the PAPR of COFDM system and reducing its effect by clipping, Selected Mapping (SLM) and Partial Transmit Sequence (PTS) techniques. COFDM system used here comply with IEEE 802.11a specifications and Reed Solomon (RS) codes along with convolution codes are used for channel coding purpose. Channel used for consideration is AWGN. The performance is evaluated in terms of PAPR value and BER.

Orthogonal Frequency Division Multiplexing (OFDM) is an encoding method that are hugely utilized in wireless communication due to its high number of advantages such as tolerance for multipath delay spread, frequency selective fading channels immune and also power efficiency. The bad side of this method is it has high Peak Average Power Ratio (PAPR) that will generate nonlinear distortions and severe power penalty. In this research, Selective Mapping (SLM) method is proposed to solve the problem of high PAPR but from previous researches, it could be seen that in SLM, the search complexity increases as the number of phase sequence increase. To solve this issue, Firefly Algorithm (FA) is applied to optimize the function of SLM. The modulation method used is Quadrature Phase Shift Keying (QPSK). By the end of the process, CCDF and BER plots are computed. The performance of PAPR reduction in OFDM system are analyzed by different number of subcarriers, phase sequences, randomization parameters and iterations using CCDF graphs. The performance of OFDM channel through AWGN channel is studied with different number of subcarriers. By using SLM method only, the PAPR values manage to be reduced by 0.4–3 dB but with FA-SLM algorithm, the PAPR values can be reduced by 5–9.5 dB. With these results, it is concluded that the combination of SLM with FA can help to improve computational complexity in SLM and eventually reduce PAPR value in OFDM system.

One major drawback of OFDM is the large Peak to Average Power Ratio (PAPR). OFDM is a linear modulation, therefore large PAPR requires large linear dynamic range of the transmitter (TX) as well as the receiver (RX) paths. The weak point in the TX-RX chain is the Power Amplifier (PA). As known, a linear PA which is able to amplify signals with large PAPR has to have a large dynamic range that results with low power efficiency, thus by reducing PAPR one may improve the efficiency of PA. A PAPR reducing method in OFDM, based on SeLective Mapping (SLM) is considered. As known, SLM requires transmitting a Side Information (SI). Increasing the SLM order reduces the PAPR but increases the size of SI. In order to transmit the SI some power and bandwidth are needed, those are taken from the total power and bandwidth budget and thus lowering the capacity. On the other hand the reduced PAPR improves the PA efficiency, thus increases the channel capacity. Accordingly maximal value of channel capacity is expected as well as an optimal SLM order.

One of the major drawbacks of OFDM system is the high peak-to-average power ratio (PAPR). This high PAPR causes nonlinear distortion of the high power amplifier (HPA). Among the studies for PAPR reduction, the partial transmit sequence (PTS) is an attractive technique to prevent nonlinear distortion. However, it causes high computational complexity. Moreover, although the random sub-block partition method can obtain the optimum PAPR reduction, it is difficult to design the random sub-block partition method in a systematic manner. In this paper, we propose a new systematic sub-block partition method which shows low computational complexity and effective PAPR reduction. Simulation results show that the PAPR performance of the proposed PTS is closely similar to the random partitioning PTS, while it has low computational complexity.

In this paper, we propose a new PAPR reduction by using a partial transmit sequences (PTS) method with coded side information (SI) technique. These methods are used in an orthogonal frequency division multiplexing (OFDM) system. The OFDM employs orthogonal sub-carriers for data modulation. These sub-carriers unexpectedly present a large peak to average power ratio (PAPR) in some cases. In order to reduce PAPR, the sequence of input data is partitioned into disjoint sub-block of PTS. If number of sub-block increases, high efficiency of PAPR reduction can be obtained. However, a quite large calculation cost must be demanded and thus it is impossible to obtain the optimum PTS. In the proposed method, we introduce a coded side information technique assuming the pseudo-optimum condition into the PTS. The total calculation cost becomes drastically reduced and side information bits for recovering original data in demodulation. In simulation results, the proposed method demonstrated the improvement of PAPR and bit error rate (BER) performance.

Recently, a hybrid single carrier(SC) and multi-carrier (MC) system based on the 4-weighted fractional Fourier transform (4-WFRFT) was proposed. As this hybrid carrier (HC) system contains MC component, it inherits the problem of high peak to average power ratio (PAPR). In this paper, we investigate the clipping technique for PAPR reduction in HC system. By analysis and simulation, we show that clipping technique is a simple and efficient way to overcome the large PAPR in HC system at the price of increased bit error ratio (BER). Furthermore, a higher MC proportion in HC leads to a worse BER performance.

Particle swarm optimization (PSO) is a swarm intelligence based computer algorithm that is used to find a solution in the search space of an optimization problem. Adding frequency diversity, through subcarrier redundancy, in orthogonal frequency-division multiplexing (OFDM) is a popular approach to improve the robustness of the system. However, frequency redundant OFDM system is prone to high peak-to-average power ratio (PAPR), due to the fact that the same source information is transmitted on multiple subcarriers. Existing schemes such as Selective Mapping (SLM) and partial transmit sequence (PTS) are effective but difficult to implement due to the high computation complexity. In this paper, we propose a two stage PAPR reduction method. We analyze the computational complexity and extensive simulations on the PAPR and show that our scheme considerably reduces the computational complexity while achieving similar PAPR reduction as SLM and better PAPR reduction than PTS.

Novel hybrid PAPR reduction schemes for the MGFDM system

The technology has been growing rapidly in the form of portable wireless devices that can perform multiple functions to cope with the state-of-the-art technology and synchronization. A total device capacity must be increased to accommodate new wireless applications. This can be achieved by leveraging new technologies, with higher data rates. Spectrum pooling has gained immense popularity, with increased demand for frequency range and bandwidth availability constraints. Statistics suggest that much of the spectrum licensed is not used all the time. Because of the transmitter's nonlinearity nature, the large (peak to average power ratio (PAPR)) phenomenon is a drawback in orthogonal frequency division multiplexing (OFDM). Several hybrid approaches have recently been implemented to minimize PAPR's high value, at the expense of increasing the level of computational complexity in the system. In this paper, a new hybrid approach has been introduced in parallel to combine the selective mapping approach (SLM) with the partial transmit sequence (PTS) approach to improve the efficiency of PAPR reduction with lower numerical method complexity. The findings reveal that the OFDM systems with the proposed hybrid approach have better efficiency in terms of PAPR elimination, side-information, and computational complexity compared to current hybrid methods. Also, a hybrid approach proposed output could be maintained without degradation. Index Terms: OFDM, PTS, PAPR, SLM

Multicarrier Waveform (MCW) has several advantages and plays a very important role in cellular systems. Fifth generation (5G) MCW such as Non-Orthogonal Multiple Access (NOMA) and Filter Bank Multicarrier (FBMC) are thought to be important in 5G implementation. High Peak to Average Power Ratio (PAPR) is seen as a serious concern in MCW since it reduces the efficiency of amplifier use in the user devices. The paper presents a novel Divergence Selective Mapping (DSLM) and Divergence Partial Transmission Sequence (D-PTS) for 5G waveforms. It is seen that the proposed D-SLM and PTS lower PAPR with low computational complexity. The work highlighted a combination of multi-data block partial transmit schemes along with tone reservation. In this, an overlapping factor is used to determine the number of data blocks for every group. Here, considering only those data blocks that have minimum signal power, the use of DSLM and DPTS are required to eliminate the segment’s peaks. Simulation results reveal that the suggested hybrid technique proves to be better than the conventional PTS scheme. Furthermore, the power saving performance of FBMC and NOMA is compared with the Orthogonal Frequency Division Multiplexing (OFDM) waveform.

SummaryIn wireless telecommunication, one of the modulation approaches used is the orthogonal frequency division multiplexing (OFDM). Moreover, the high peak‐to‐average power ratio (PAPR) is the one notorious demerit in OFDM systems. Hence, the high power amplifier (HPA) is used in its linear region. Otherwise, the bit error rate (BER) will be increased. Several approaches are proposed in the wireless communications for reducing the PAPR issue. In this paper, we propose a hybrid Discrete Hartley Matrix Transform (DHMT) precoding using both selected mapping (SLM) and partial transmit sequence (PTS) PAPR reduction strategies. For the multicarrier modulation process, instead of Inverse Fast Fourier transform (IFFT) operation, the DHMT operation is used because of its low computational complexity. Based on multi‐chaotic, the time‐frequency domain encryption (TFDE) approach is adopted for physical layer security to confirm the security in data transmission. For enhancing the physical layer security, the proposed encryption system generates chaotic sequences based on Logistic maps and Lozi in the frequency and time domains together. In this study, the implementation of the DHMT‐based OFDM system is processed to reduce the maximum PAPR. Implementation is performed on the MATLAB platform, and the performances are calculated using complementary cumulative distribution function (CCDF), BER regards to signal‐to‐noise ratio (SNR), and the outputs are compared based on the computation time. However, compared with the existing models, the proposed model produced better PAPR minimization regarding SNR.

Both selective mapping (SLM) and partial transmit sequences (PTSs) are multiple signal representation (MSR) techniques used to reduce the peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Given the same number of candidate signals, SLM is superior to PTS in improving PAPR performance. However, SLM is associated with greater computational complexity, as more inverse discrete Fourier transforms (IDFTs) are required for SLM in comparison with PTS. To address this issue, this study proposes an improved SLM scheme, which divides available subcarriers into two parts, with one part used in PTS and the other in SLM. The proposed method determines whether PTS or SLM is to be used by input signals by setting an adaptive threshold, which can reduce the number of IDFTs accumulated over the implementation of SLM following a large number of OFDM signal transmissions. Statistical analysis of the simulation results show that after a large number of OFDM signals are transmitted, the proposed method not only reduces the number of IDFTs accumulated, but also allows each transmit signal to have PAPR‐reduction performance equivalent to that of conventional SLM schemes.