Design and Implementation of OFDM System using QPSK & QAM

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Arun Kumar ◽  
Hemant Rathore
Keyword(s):  
Binary Data ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Frequency Division ◽  
Computer File ◽  
Multiple User ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
User Access

AbstractIn this work, OFDM (orthogonal frequency division multiplexing) is analyzed for different transmission schemes on the basis of BER (Bit Error Rate), transmitting-receiving signal, constellation diagram and the best transmitting scheme is determined for OFDM. OFDM is analogous to Frequency Division Multiple Access (FDMA) in which the multiple user access is achieved by sub-dividing the existing spectrum into various channels, which are then allocated to users. In this paper Mat-lab simulation OFDM is used to see, how the Bit Error Ratio (BER) of a transmission varies when signal to Noise Ratio (S/N) and Multi-Propagation effect are altered to transmit a computer file in binary data from modulated by 16-QAM and QPSK modulation, finally at the end of the transmission, when the receiver receives the data, a comparison of the transmitted and the received messages is done in order to calculate the Bit Error Ratio (BER).

A Novel ZF-Based MAI Cancellation Scheme in the Time Domain for SC-FDMA System

2013 ◽  
Vol 427-429 ◽  
pp. 2432-2435
Author(s):  
Yu Lei Zhang ◽  
Tian Yuan Zhang ◽  
Shu Xin Guo
Keyword(s):  
Time Domain ◽  
Carrier Frequency ◽  
Multiple Access ◽  
Carrier Frequency Offset ◽  
Frequency Division ◽  
Single Carrier ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
The Time Domain ◽  
Multi Access

Similar to the orthogonal frequency division multiple access (OFDMA) system, the carrier frequency offset (CFO) is a challenging problem in the single carrier frequency division multiple access (SC-FDMA) system, which can destroy the orthogonality among the subcarriers. As a consequence, multi-access interference (MAI) along with serious performance degradation will be induced. In this paper, a zero forcing (ZF)-based MAI cancellation scheme is proposed. Compared with other cancellation schemes, the proposed one mitigates the interferences in the time domain instead of the frequency domain. Simulation results show that the proposed method can significantly reduce the degradation and enhance the Bit Error Ratio (BER) performance.

scholarly journals Linear and Non-Linear Companding Transformation Reducing PAPR in OFDM Signals

2019 ◽  
Vol 8 (11S2) ◽  
pp. 461-463
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Sigmoid Function ◽  
Power Ratio ◽  
Frequency Division ◽  
Time Zone ◽  
Error Ratio ◽  
Nonlinear Power Amplifier ◽  
Bit Error Ratio ◽  
Ofdm Signals

An important disadvantage of Orthogonal Frequency Division Multiplexing (OFDM) signals is high peakto-average power ratio (PAPR), causing genuine debasement popular execution when a nonlinear power amplifier (PA) is utilized. A notable technique to diminish power ratio deprived of confinements on framework parameters is Companding Transform (CT), for example, the sum of subcarriers, outline organization, and gathering type. Another nonlinear companding change, the utilization of hyperbolic transfer sigmoid function capacity is proposed for PAPR decrease in this paper. The proposed methodology extends the little flag and packs the pinnacle flag in the time zone at the same time without changing the average power. Results dependent on MATLAB demonstrate that the proposed methodology increases additional pinnacle decrease and improves the BER (bit error ratio)execution.

scholarly journals Performance analysis of OFDMA and SC-FDMA

2017 ◽  
Vol 8 (2) ◽  
pp. 113-116 ◽  
Author(s):  
M. Al-Rawi
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
High Speed ◽  
Minimum Mean Square Error ◽  
Frequency Division ◽  
International Telecommunication Union ◽  
Single Carrier ◽  
Main Challenge ◽  
Better Than

The main challenge in any high-speed digital communication system is how to maximize the data rate with minimizing the bit error rate. Several techniques have been developed to achieve this point. Some of these techniques are orthogonal frequency division multiplexing (OFDM), single-carrier frequency domain equalization (SC-FDE), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA). These four techniques are described briefly in this paper. Also, the paper measures the performances of OFDMA and SC-FDMA systems over international telecommunication union (ITU) vehicular-A channel using minimum mean square error (MMSE) equalization. Simulation results show that the performances with interleaved mapping outperform that with localized mapping. Also, the performances with quadrature phase shift keying (QPSK) are better than that with 16-ary quadrature amplitude modulation (16QAM). In addition, the performance of SC-FDMA is better than that of OFDMA, when QPSK is used, but the latter is little bit better than that of SC-FDMA when 16QAM is used.

scholarly journals NOMA for Multinumerology OFDM Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ayman T. Abusabah ◽  
Huseyin Arslan
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Superposition Coding ◽  
Promising Technique ◽  
Successive Interference Cancelation ◽  
Power Domain ◽  
Multiple Access Schemes ◽  
Spectrally Efficient

Nonorthogonal multiple access (NOMA) is a promising technique which outperforms the traditional multiple access schemes in many aspects. It uses superposition coding (SC) to share the available resources among the users and adopts successive interference cancelation (SIC) for multiuser detection (MUD). Detection is performed in power domain where fairness can be supported through appropriate power allocation. Since power domain NOMA utilizes SC at the transmitter and SIC at the receiver, users cannot achieve equal rates and experience higher interference. In this paper, a novel NOMA scheme is proposed for multinumerology orthogonal frequency division multiplexing system, that is, different subcarrier spacings. The scheme uses the nature of mixed numerology systems to reduce the constraints associated with the MUD operation. This scheme not only enhances the fairness among the users but improves the bit error rate performance as well. Although the proposed scheme is less spectrally efficient than conventional NOMA schemes, it is still more spectrally efficient than orthogonal multiple access schemes.

scholarly journals BER performance study for optical OFDM of optical camera communication

2021 ◽  
Vol 11 (5) ◽  
pp. 4263
Author(s):  
Noor J. Jihad ◽  
Sinan M. Abdul Satar
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Frequency Division ◽  
Performance Study ◽  
Mapping Rule ◽  
Bit Loading ◽  
Dc Bias ◽  
Optical Ofdm ◽  
Ber Performance ◽  
Optical Camera Communication

In this article, different forms of optical orthogonal frequency division multiplexing (OFDM) were observed which were suitable for optical camera communication (OCC) systems. This research aims to establish the bit error rate (BER) versus signal-to-noise ratio (SNR) of the OCC system. This research will focus on OCC systems and the design that produces the noise of the clipping but will gain SNR as a whole if an optimum clipping factor is chosen. The BER versus SNR analysis was investigated for the different clipping factors 0.7, 1.4, and 2.6. The BER performance of the asymmetrically clipped optical OFDM (ACO-OFDM) was also compared with the direct current optical OFDM (DCO-OFDM) to show the suitable effectiveness of the proposed approach. ACO-OFDM was considered to be better due to lower bit loading, but DCO-OFDM was efficient for higher SNR values. This was because the DC bias used was inefficient in terms of optical capacity, while ACO-OFDM used only half of the subcarriers to transmit the information. Moreover, ACO-OFDM two-dimensional half-subcarriers of mapping rule would introduce the clipping noise to its unused 2D subcarriers, although further data can be provided by the 2D DCO-OFDM mapping rule.

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