scholarly journals DFT-Spread Spectrally Overlapped Hybrid OFDM–Digital Filter Multiple Access IMDD PONs

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5903
Author(s):  
Abdulai Sankoh ◽  
Wei Jin ◽  
Zhuqiang Zhong ◽  
Jiaxiang He ◽  
Yanhua Hong ◽  
...  
Keyword(s):  
Digital Filter ◽  
Multiple Access ◽  
Forward Error Correction ◽  
Direct Detection ◽  
Transmission Rate ◽  
Signal Transmission ◽  
Average Power ◽  
Direct Consequence ◽  
Papr Reduction ◽  
Power Budget

A novel transmission technique—namely, a DFT-spread spectrally overlapped hybrid OFDM–digital filter multiple access (DFMA) PON based on intensity modulation and direct detection (IMDD)—is here proposed by employing the discrete Fourier transform (DFT)-spread technique in each optical network unit (ONU) and the optical line terminal (OLT). Detailed numerical simulations are carried out to identify optimal ONU transceiver parameters and explore their maximum achievable upstream transmission performances on the IMDD PON systems. The results show that the DFT-spread technique in the proposed PON is effective in enhancing the upstream transmission performance to its maximum potential, whilst still maintaining all of the salient features associated with previously reported PONs. Compared with previously reported PONs excluding DFT-spread, a significant peak-to-average power ratio (PAPR) reduction of over 2 dB is achieved, leading to a 1 dB reduction in the optimal signal clipping ratio (CR). As a direct consequence of the PAPR reduction, the proposed PON has excellent tolerance to reduced digital-to-analogue converter/analogue-to-digital converter (DAC/ADC) bit resolution, and can therefore ensure the utilization of a minimum DAC/ADC resolution of only 6 bits at the forward error correction (FEC) limit (1 × 10−3). In addition, the proposed PON can improve the upstream power budget by >1.4 dB and increase the aggregate upstream signal transmission rate by up to 10% without degrading nonlinearity tolerances.

scholarly journals PAPR Reduction of OFDM Signals by Novel Global Harmony Search in PTS Scheme

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Hojjat Salehinejad ◽  
Siamak Talebi
Keyword(s):  
Smart Grids ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal Transmission ◽  
Harmony Search ◽  
Average Power ◽  
Wind Farms ◽  
Papr Reduction ◽  
Power Ratio ◽  
Frequency Division ◽  
Ofdm Signals

The orthogonal frequency division multiplexing (OFDM) modulation technique is one of the key strategies for multiuser signal transmission especially in smart grids and wind farms. This paper introduces an approach for peak-to-average power ratio (PAPR) reduction of such signals based on novel global harmony search (NGHS) and partial transmit sequence (PTS) schemes. In PTS technique, the data block to be transmitted is partitioned into disjoint subblocks, which are combined using phase factors to minimize PAPR. The PTS requires an exhaustive search over all combinations of allowed phase factors. Therefore, with respect to the fast implementation and simplicity of NGHS technique, we could achieve significant reduction of PAPR.

scholarly journals A Performance Analysis of a Hybrid OCDMA-PON Configuration Based on IM/DD Fast-OFDM Technique for Access Network

2020 ◽  
Vol 10 (21) ◽  
pp. 7690
Author(s):  
Hichem Mrabet
Keyword(s):  
Wavelength Division Multiplexing ◽  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Average Power ◽  
Access Network ◽  
Optical Power ◽  
Passive Optical Network ◽  
Free Access ◽  
Power Budget ◽  
Budget Analysis

The purpose of this article is to propose a new configuration based on OCDMA and Fast-OFDM techniques for access network applications. A hybrid intensity modulation with direct detection, fast orthogonal frequency-division multiplexing–code division multiplexing access (IM/DD Fast-OFDM-CDMA) system is analytically and numerically evaluated for an amplifier-free access network. Therefore, system performance is analytically investigated in terms of bit error rate/Q-factor as a function of simultaneous users, fiber length and launched optical power. Firstly, the proposed analytical model includes the overlapping effect among OFDM subcarriers, the peak-to-average power ratio (PAPR), and multiple access interference (MAI). Secondly, a simulation setup is performed, allowing four simultaneous users operating at 40 Gb/s in a passive optical network (PON) context. Furthermore, a power budget analysis is made between IM/DD Fast-OFDM-CDMA, all-optical IM/DD OFDM-CDMA (IM/DD AO-OFDM-CDMA) and OCDMA wavelength division multiplexing (OCDMA-WDM) configurations. It is shown that at 40 Gb/s and by using 2D-hybrid coding (2D-HC), the maximum achievable transmission-reach of IM/DD Fast-OFDM-CDMA is 142 km, which is 34 km and 60 km higher than those provided by the IM/DD AO-OFDM-OCDMA and OCDMA-WDM PON configurations, respectively.

scholarly journals Performance Analysis of WOFDM-WiMAX Integrating Diverse Wavelets for 5G Applications

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lavish Kansal ◽  
Gurjot Singh Gaba ◽  
Ashutosh Sharma ◽  
Gaurav Dhiman ◽  
Mohammed Baz ◽  
...  
Keyword(s):  
Multiple Access ◽  
Rayleigh Fading ◽  
Signal To Noise Ratio ◽  
Average Power ◽  
Telecommunication Networks ◽  
Papr Reduction ◽  
Mobile Wimax ◽  
Discrete Wavelet ◽  
Frequency Division ◽  
Mobile Telecommunication

In the 5th generation (5G) and 6th generation (6G) of wireless mobile telecommunication networks, the requests for an elevated data rate with access to stationary as well as portable customers are going to be overwhelming. Mobile worldwide interoperability for microwave access (WiMAX) comes out as a favourable alternative that is intelligibly developed and more matured than wireless fidelity (Wi-Fi). Mobile WiMAX makes use of the orthogonal frequency division multiple access (OFDMA) technology for its two-way communication to enhance the system performance in fading environments making it more suitable for 5G applications. The diverse OFDM forms deliberated here are the fast Fourier transform- (FFT-) based WiMAX and discrete wavelet transform- (DWT-) based WiMAX. The suggested study exhibits the bit error rate (BER) and peak to average power ratio (PAPR) reduction by integrating different wavelet families, i.e., Haar, symlet, coiflet, and reverse biorthogonal over Rayleigh fading channel. The simulation results obtained by MATLAB depicts an improvement in PAPR reduction, and signal to noise ratio (SNR) requirement is also reduced by 6-12 dB by using DWT-incorporated WiMAX at a BER of 10-4.

Hadamard Transform Combined with PTS for PAPR Reduction in Direct-Detection Optical OFDM System

2014 ◽  
Vol 1061-1062 ◽  
pp. 1194-1197
Author(s):  
Hui Li ◽  
Xu Zhang ◽  
Lei Guo ◽  
Ye Jun Liu ◽  
Xiao Xue Gong ◽  
...  
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Average Power ◽  
Papr Reduction ◽  
Hadamard Transform ◽  
Ofdm System ◽  
Partial Transmit Sequence ◽  
Ofdm Signal ◽  
Optical Ofdm ◽  
Complementary Techniques

High Peak-to-Average Power Ratio (PAPR) of the Orthogonal Frequency Division Multiplexing (OFDM) signal is one of the limitations to the transmission performance of optical OFDM system. In this paper, we propose a novel hybrid PAPR reduction technique called Hadamard Transform Combined with Partial transmit sequence (HTCP). The proposed HTCP scheme combines the merits of two complementary techniques, i.e., Hadamard transform and Partial Transmit Sequence (PTS), to improve the performance of the optical OFDM system in terms of PAPR and Bit Error Rate (BER). Simulation results show that the HTCP scheme has better performance with regard to PAPR and BER compared with the case of applying only the Hadamard transform or PTS technique.

scholarly journals Optimized Scheduling Technique of Null Subcarriers for Peak Power Control in 3GPP LTE Downlink

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Soobum Cho ◽  
Sang Kyu Park
Keyword(s):  
Power Efficiency ◽  
Multiple Access ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Average Power ◽  
Papr Reduction ◽  
Single Input Single Output ◽  
Single Output ◽  
Multiple Input ◽  
Input Multiple Output

Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system.

scholarly journals Analytical Framework of CP-Free Multiuser OFDM System for Coordinated Multi-Point at mmWave

2021 ◽  
Vol 11 (16) ◽  
pp. 7605
Author(s):  
Joarder Jafor Sadique ◽  
Saifur Rahman Sabuj ◽  
Shaikh Enayet Ullah ◽  
Md. Akbar Hossain ◽  
Raad Raad ◽  
...  
Keyword(s):  
Channel Coding ◽  
Forward Error Correction ◽  
Average Power ◽  
Analytical Framework ◽  
Papr Reduction ◽  
Achievable Rate ◽  
Cell Edge ◽  
Noise Ratio ◽  
The Impact ◽  
Multiuser Ofdm

In this paper, a coordinated multipoint joint transmission (CoMP-JT) framework at mmWave for a cyclic prefix (CP)-free multiuser OFDM wireless communication system is developed and analyzed. The aim is to provide high-quality service to cell-edge users; otherwise, the cell-users would suffer from significant signal degradation due to undesired interference. The impact of complex Hadamard transform with block diagonalization channel precoding for multiuser interference reduction and designed subcarrier mapping for out-of-band (OOB) reduction are investigated. In addition, the paper studied the input back-off-aided high-power amplifier for peak-to-average power ratio (PAPR) reduction and forward error correction channel coding for improved bit error rate (BER) for cell-edge users at mmWave frequencies. Moreover, signal-to-interference-noise ratio and ergodic achievable rate are estimated both in the presence and absence of CoMP-JT-based transmission technique to verify their significance in terms of transmitted power. Numerical investigations showed an OOB reduction of 312 dB, PAPR reduction from 17.50 dB to 7.66 dB, and improved BER of 1×10−3 in 16-QAM for a signal-to-noise ratio of −6 dB. Hence, the simulation results demonstrated the effectiveness of the developed system.

scholarly journals Research on PDMA communication system based on Complete Complementary Sequence

2020 ◽  
Author(s):  
Shufeng Li ◽  
Baoxin Su ◽  
Libiao Jin
Keyword(s):  
Power Allocation ◽  
Spread Spectrum ◽  
Communication System ◽  
Multiple Access ◽  
Large Scale ◽  
Transmission Rate ◽  
Average Power ◽  
System Model ◽  
Complementary Sequence ◽  
Allocation Algorithm

Abstract Pattern division multiple access (PDMA) is a new non-orthogonal multiple access (NOMA) technology. It is proposed to meet the challenge of 5G large-scale connectivity and high-frequency spectral efficiency. Compared with traditional orthogonal multiple access (OMA), PDMA can support more users through the allocation of non-orthogonal resources. Due to perfect aperiodic correlation, complete complementary sequences (CCS) still has research value in 5G. In order to apply the advantages of CCS to NOMA communication system, this paper proposes a system model of CCS spread spectrum coding based on PDMA. CCS is used as spread spectrum code to improve the performance of PDMA communication system. At the same time, on the basis of spread spectrum technology, this paper analyzes the average power allocation algorithm and water-filling power allocation algorithm, and a dynamic power allocation algorithm based on the transmission rate and practical application is proposed. The simulation results show that the system model can effectively improve the performance of the system.

Multiple Access using Time Modulated Array with Single RF Chain

2019 ◽  
Vol 12 (5) ◽  
pp. 395-401
Author(s):  
Xu He ◽  
Yuan Ding ◽  
Gaojian Huang
Keyword(s):  
Power Efficiency ◽  
Multiple Access ◽  
Narrow Band ◽  
Average Power ◽  
Access Technology ◽  
Signal Peak ◽  
Single Radio ◽  
Rf Chain ◽  
Synthesis Approach ◽  
Single Rf Chain

Background: A new wireless multiple access technology enabled by using Time Modulated Arrays (TMAs) is proposed in this paper. Methods: It benefits due to the requirement of only a single Radio Frequency (RF) chain, compared with other multiple-RF-chain schemes. Results: As a result, it is able to greatly reduce the system cost, energy consumption, and complexity. Conclusion: In addition, the signal through the single RF chain is narrow-band modulated, reducing the signal Peak-to-Average-Power-Ratio (PAPR), thus, further enhancing the power efficiency of the RF chain, especially for power amplifiers. The operation principle and synthesis approach are elaborated in this paper, and are demonstrated with two examples.

scholarly journals Optimal Multi-Antenna Transmission for the Cooperative Non-Orthogonal Multiple-Access System

2021 ◽  
Vol 11 (5) ◽  
pp. 2203
Author(s):  
Duckdong Hwang ◽  
Janghoon Yang ◽  
Sung Sik Nam ◽  
Hyoung-Kyu Song
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Average Power ◽  
Access Point ◽  
Power Performance ◽  
Multiple User ◽  
Structure Simulation ◽  
Rank One ◽  
Multiple Access System ◽  
Optimal Beamforming

We investigate the beamforming for the multi antenna cooperative non-orthogonal multiple access (NOMA) system, where an access point (AP) delivers messages for multiple user terminals (UT) with successive interference cancellation (SIC) reception method. Some UTs with multiple antennas cooperate with the AP transmission to improve the diversity and the average power performance. We formally present two optimal beamforming schemes at the AP and at the cooperative UTs. One scheme has no power limitation for the cooperative UTs, while the other one does have such limitation. We guarantee that the rank one beamformer is sufficient to achieve the optimal points so that the proposed schemes have rank one semi-definite programming (SDP) structure. Simulation results show the performance gain of the multi-antenna cooperative NOMA schemes in the sense of diversity and the average power.

scholarly journals Autonomous Power Decision for the Grant Free Access MUSA Scheme in the mMTC Scenario

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 116
Author(s):  
Wissal Ben Ameur ◽  
Philippe Mary ◽  
Jean-François Hélard ◽  
Marion Dumay ◽  
Jean Schwoerer
Keyword(s):  
Interference Cancellation ◽  
Error Propagation ◽  
Multiple Access ◽  
Transmission Rate ◽  
Free Access ◽  
Decoding Complexity ◽  
Machine Type ◽  
Machine Type Communications ◽  
Multiple Access Schemes ◽  
Lower Complexity

Non-orthogonal multiple access schemes with grant free access have been recently highlighted as a prominent solution to meet the stringent requirements of massive machine-type communications (mMTCs). In particular, the multi-user shared access (MUSA) scheme has shown great potential to grant free access to the available resources. For the sake of simplicity, MUSA is generally conducted with the successive interference cancellation (SIC) receiver, which offers a low decoding complexity. However, this family of receivers requires sufficiently diversified received user powers in order to ensure the best performance and avoid the error propagation phenomenon. The power allocation has been considered as a complicated issue especially for a decentralized decision with a minimum signaling overhead. In this paper, we propose a novel algorithm for an autonomous power decision with a minimal overhead based on a tight approximation of the bit error probability (BEP) while considering the error propagation phenomenon. We investigate the efficiency of multi-armed bandit (MAB) approaches for this problem in two different reward scenarios: (i) in Scenario 1, each user reward only informs about whether its own packet was successfully transmitted or not; (ii) in Scenario 2, each user reward may carry information about the other interfering user packets. The performances of the proposed algorithm and the MAB techniques are compared in terms of the successful transmission rate. The simulation results prove that the MAB algorithms show a better performance in the second scenario compared to the first one. However, in both scenarios, the proposed algorithm outperforms the MAB techniques with a lower complexity at user equipment.

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