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Transmitter structure of a BPSK Cyclic-SLM encoder.
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This paper proposed a PAPR reduction method for BPSK OFDM systems and 16-QAM OFDM systems respectively. The strategy of the algorithms is to use a correction subcode for error control and a scrambling subcode for PAPR control. The transmitted OFDM sequence is selected with minimum PAPR from a number of candidates which form a coset of scrambling su...
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... + Y to c ∈ C by syndrome decoding whenever b and y have the same syndrome, i.e., Hb = Hy, where H is a parity check matrix of C. We can further simplify the decoding by using cyclic codes for encoding and scrambling. A proposed modified SLM algorithm using two disjoint binary cyclic codes for OFDM systems with 2 m − 1 BPSK subcarriers is shown in Fig. 1. We assume ...
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... Second strategy, is more smooth and preferable. The available data scrambling strategies in literature are Block coding [10,11], Selected Mapping (SLM) [12][13][14][15] and Partial Transmit Sequences (PTS) [16]. SLM and PTS are probabilistic methods of PAPR reduction. ...
Power efficiency is one of the key parameter in Fifth Generation (5G) wireless network design with portable standard devices. The solution to enhance the power efficiency of Power Amplifier (PA) to be used for 5G, underlies in lowering the Peak-to-Average Power Ratio (PAPR) of 5G signaling waveform. Signaling candidates of 5G encompasses the multicarrier transmission and also uses strategically different mapper and channel coding schemes for processing the various logical and physical channels. In this article, we have proposed and analyzed the performance of Data Scrambled Selected Mapping (DS-SLM) PAPR reduction technique with polar coded sequences in the presence of Quadrature Amplitude Modulation (QAM) with 16-QAM, 64-QAM and 256-QAM, Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK). Our MATLAB simulation results shows 32.04% PAPR reduction for BPSK, 61.85% PAPR reduction for QPSK and 66.96% PAPR reduction for QAM with the proposed DS-SLM technique compared to conventional Selected Mapping (SLM) technique. We have also provided the Bit Error Rate (BER) performance curves. In this article, computational complexity of proposed method is analyzed and compared with other probabilistic approaches. We have achieved average net power gain of 3.84 dB in BPSK and 13.73 dB in QPSK using proposed technique compared to conventional SLM. We have also studied the effect of PAPR reduction on network coverage area and range of wireless communications.
... Hence signal warping approach is generally avoided. Signal disordering approach is most favorable such as Block Coding with Error Correction [9][10][11], Selected Mapping (SLM) [12][13][14], Partial Transmit Sequence (PTS) [15,16] and Interleaving [17]. PAPR reduction algorithms available from both approaches have their own computations and complexities. ...
Fourth Generation (4G) mobile communication system uses Orthogonal Frequency Division Multiplexing (OFDM). With this technique, high data rate demands are achieved. Tail biting Convolution Coding (TBCC) avoids the data rate loss, hence it is widely used error control coding algorithm in OFDM and other various wireless communication technologies. But, OFDM has increased Peak to Average Power Ratio (PAPR). High PAPR signal consumes more power and makes system power inefficient. To gain supercomputing performance in terms of Speed, Memory and Power on mobile devices, an efficient implementation of algorithms on Digital Signal Processing (DSP) processor is an essential requirement. This requirement becomes more stringent for Fifth Generation (5G) mobile devices. For this, wide scope of knowledge as well as skills are required to understand the algorithm, DSP architecture, instruction set, optimization and performance measurement. In this article, we have implemented TBCC algorithm using Bit by Bit (BYB) and Look Up Table (LUT) approaches on Freescale StarCore SC140 based DSP platform and proposed an efficient algorithm implementation methodology by comparing the machine cycles and memory requirement. We have used coding rate (R) = 1/2, 1/3, 1/4 and constraint length (K) = 5 and K = 9 for implementation of TBCC. Using our proposed LUT approach, we have achieved average 45.82% Computational Complexity Reduction Ratio (CCRR) in machine cycles compared to BYB approach. Proposed LUT approach increases the TBCC execution speed. Our developed fixed point routines can be used for any K ≤ 9. TBCC is also analyzed for PAPR to get an overall profiling results and three dimensional optimization of TBCC algorithm in terms of Speed, Memory and Power.
... 5 Hence, PAPR is one of the important issues that attracts the attentions of researchers who were dealing with the OFDM system. Various techniques to reduce PAPR in the conventional radio frequency-based OFDM systems were implemented such as clipping 17 and filtering, 18 peak windowing 19 and companding, 20 selective mapping, 21,22 partial transmit sequence, 23 encoding, 24 and the discrete Fourier transform (DFT)-spread OFDM technique. 25 However, application of these techniques to reduce the PAPR in optical intensity modulation/direct detection (IM/DD) systems has received much less attention. ...
A dual stream asymmetrically clipped optical (DSACO)-orthogonal frequency division multiplexing (OFDM) with intensity modulation/direct detection receiver is proposed that combines the ACO-OFDM, which is generated from individual streams of odd and even frequencies in a single frame without loss of information. The clipping noise, which is its absolute value, is subtracted from even subcarriers of DSACO-OFDM signal and further delayed in time domain to recover the ACO-OFDM data of the odd stream. The proposed DSACO has the same spectral efficiency of DC-biased optical OFDM (DCO-OFDM). It performs better in terms of optical signal-to-noise ratio (OSNR) and peak-to-average power ratio (PAPR) when compared to ASCO-OFDM and Lowery's layered/enhanced ACO-OFDM (L/E ACO-OFDM). For a bit error rate of 10 -3, DSACO shows around 1.9, 3.4, and 7.6 dB improvements of OSNR over two-layered L/E ACO-OFDM, three-layered L/E ACO-OFDM, and ASCO-OFDM for 1024-quadrature amplitude modulation constellations, respectively. The complimentary cumulative distributive function of PAPR for DSACO achieves 0.27 dB lower PAPR than three-layered L/E ACO-OFDM system and 1.17 dB lower PAPR than two-layered L/E ACO-OFDM and ASCO-OFDM. © 2018 Society of Photo-Optical Instrumentation Engineers (SPIE).
... Again, they demonstrated that the (Turbo) encoder can be used for error correction and PAPR reduction, and that the turbo code improves the PAPR and BER performance as compared to an OFDM system with uncoded data, which uses SLM for PAPR reduction. Next, [73] extended the EC-SLM technique with the use of cyclic codes with SLM for BPSK, and combining block-coded modulation (BCM) with SLM for 16-QAM OFDM. ...
Orthogonal frequency division multiplexing (OFDM) is an efficient multi-carrier modulation technique for wireless communication. However, one of the main drawbacks encountered in implementing it is its resultant high peakto- average power ratio (PAPR). Many techniques have been proposed in the literature to substantially decrease the peaks in the OFDM signal. The problem with these, however, is that their effects on other parameters are not always positive. These effects include a decrease in the bit error rate (BER), an increase in complexity, or a reduction in the bit rate. The objective of this paper is to describe the PAPR problem in a bid to reduce the peaks in the OFDM signal. The paper proposes a classification, performance evaluation and optimization of PAPR reduction techniques for commercial, public safety and tactical applications. In the taxonomy proposed herein, we also include a new category, namely, hybrid techniques. Furthermore, we compare the principal characteristics through a complementary cumulative distribution function (CCDF) and BER evaluation, and conclude on the importance of hybrid techniques when the goal is to both improve the BER and reduce the PAPR.
... Turbo codes combined with selective mapping also reduces the PAPR in the system up to some level [9,10] but it makes the system quite complex due to large computations. Combination of Selective mapping with cyclic codes for BPSK (Binary Phase Shift Keying) OFDM system produces great results in PAPR reduction and also increases the bandwidth efficiency but computation increases as the number of iterations are increased which results in complex system [11]. SLM with Logarithmic companding achieve better results as compared to conventional SLM [12] with a phase sequence up to 16 and leads to less complexity of the system. ...
OFDM (Orthogonal Frequency Division Multiplexing) has been raised a new modulation technique for next generation 4G networks e.g. LTE. But OFDM has a major drawback that is high value of PAPR at the transmitter end. Since OFDM is only used in the downlink of 4G networks therefore to reduce the problems of high PAPR (Peak to Average Power Ratio) in OFDM, some techniques e.g. SLM, PTS, Clipping, Coding, & Pre-coding etc. are suggested but none of them reduces the PAPR to an acceptable value. But a new reduction technique based on constant modulus algorithm shows great improvement in the PAPR value which has been discussed in this paper.
... Larger peaks lead to reduced power efficiency, signal distortion, and an increased complexity of a digital-to-analog and analog-to-digital converters [3]. Various methods have been proposed to control the PAPR of the transmitted signals in OFDM systems [4], including deliberate clipping [5], transmit filtering [6], companding [7], block coding [8], partial transmit sequence (PTS) [9], selective mapping (SLM) [10], tone reservation [11], and constellation extension [12]. Probabilistic methods, such as SLM and PTS, can achieve PAPR reduction with only a small rate of data loss [1]. ...
The high peak-to-average power ratio (PAPR) is one of the major problems of orthogonal frequency division multiplexing (OFDM) systems in wireless transmission. Therefore, partial transmit sequence (PTS), a promising scheme that can provide good PAPR reduction performance, has been proposed for OFDM transmission to eliminate distortion. The PTS method divides the input data block into disjoint sub-blocks, computes Inverse Fourier Transform of the subblocks, rotates the sub-blocks with appropriate phase factors and combines them to form the transmitted signal. This paper presents an enhanced PTS approach that combines two PTS partitioning schemes (adjacent and interleaved) to effectively reduce the PAPR of the OFDM systems. The influence of the proposed approach on performance is investigated by varying the size of the disjoint sub-blocks. The PAPR reduction performance of the proposed PTS method is compared with two well known sub-blocks partitioning schemes, namely, Adjacent Partitioning (AP), Interleaved Partitioning (IP). The various computer simulation results for the various sub-blocks confirmed that the proposed method provides better PAPR reduction performance compared with AP and IP partitioning based PTS scheme. In addition, these PTS schemes largely depend on the chosen size of the partitions.
... Another solution is to use selective mapping method [13]. The entire data stream is divided into different blocks of N symbols each. ...
Orthogonal Frequency Division Multiplexing (OFDM) is a veryattractive technique for high-data-rate transmission in wirelessand wired applications. The main drawback of the OFDMtechnique is its high peak to average power ratio(PAPR). Severalapproaches exists to reduce PAPR of OFDM symbols. Precodingis a new method which is having less complexity compared tothe other power reduction techniques and also it can reducePAPR considerably and results in no distortion. Error controlcoding(convolution coding is used here) can also be introducedalong with the Precoding technique in order to improve the biterror rate performance. Clipping and filtering with boundeddistortion is a simple method and provides a high PAPRreduction at the cost of signal distortion. we can restrict thisdistortion within a particular limit using bounded distortionalgorithm(BD). In this paper the PAPR reduction is obtained bycombining the precoding method and clipping technique with BDi.e. this modified method takes the advantages of two PAPRreduction technique. This paper presents various computersimulation results to verify the effectiveness of this modifiedprecoding method.
In this paper, a new suboptimal tone reservation (TR) algorithm with fixed phase rotation method based on Constant Amplitude Zero Auto-Correlation (CAZAC) sequence is proposed to reduce peak-to-average power ratio (PAPR) in multicarrier code division multiple access (MC-CDMA) systems. To decrease tone searching complexity of TR method, CAZAC sequences is utilized as initial tone candidates. To reduce searching time and remain excellent PAPR reduction performance, fixed phase rotation method is applied for the phase optimization of tone sequence to find final sub-optimal tone signals. In order to maintain average transmission power, additional constraint on the power of tone signals is supposed. Simulation results shows, by using CAZAC sequence as initial tone candidates and fixed phase rotation method for phase optimization, considerable PAPR reduction efficiency can be achieved accompanying with reduced computational time and system complexity compared with the traditional TR method.
