Performance analysis of BER in OFDM-RoF system using 16-QAM modulation for wireless network

Orthogonal Frequency Division Multiplexing (OFDM) is a modulation technique to transmit wired and wireless media. Radio over Fibre (RoF) system consists of both wireless and optical links. It is proved technology for the wireless access technique, and the OFDM has core technology for major part of the wireless network. The OFDM-RoF system is the subject of much research of various topics at the moment. OFDM-RoF system provides high speed, large capacity and high spectral efficiency in the recent 4G and upcoming 5G mobile technology with fast data transmission. OFDM has specific modulation methods such as PSK, BPSK, QPSK, and QAM techniques. The aim of this paper is to perform and simulate BER and Q-Factor of OFDM-RoF system at different parameters, including 16-QAM modulation technique using OptiSystem13.0 simulation software.

Radio over fiber (RoF) system is the most appropriate combination of fiber optic link and radio waves. Orthogonal frequency division multiplexing (OFDM)-RoF system can increase the capacity of modulation radio frequency (RF) access with high speed data transmission. The purpose of this paper is modeling and simulation an OFDM-RoF system for fiber length up to 100 km by using 16-quadrature amplitude modulation (16-QAM). OptiSystem 13 software is used for simulation. The proposed model of OFDM-RoF system uses two low pass cosine roll off filter (LP-CROF) as filter at the OFDM stage output and two LiNb-Mach Zehnder modulator (LiNb-MZM) as optical modulator. The results of simulation include the spectrum signal visualizers at the OFDM output, RF to optical upconventer (RTO) output as well as 16-QAM received constellation. The results of simulation have shown that increasing of roll off factor value, it will be broadening in filter band transition. The proposed of RoF-OFDM system is able to achieve fiber length up to 100 km uses 16 QAM sequence bit, the received power is 71.617 dBm with electrical and optical amplifications by using 10 Gbps data signal.

The demand for high-speed mobile wireless communications is rapidly growing. Orthogonal Frequency Division Multiplexing (OFDM) technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems of the near future. The practical results will be more yielding when the OFDM is combined with Radio Over Fiber technology (ROF). This project presents an investigation of the performance of OFDM-ROF system based on papers [95] [96] [97] [98] in terms of peak power reduction capability and degradation of channel capacity. OFDM is an attractive technique for achieving high-bit-rate wireless data transmission. However, the potentially large peak-to-average power ratio (PAPR) of a multicarrier signal has limited its application. The analysis is based on three sections 1. Peak to average power ratio 2. Signal distortion and channel capacity 3. ROF transmission. This report is organized as follows. After the introduction in the second chapter, OFDM and its principles are studied. Thirdly, is a throughput on the basic ROF technology. The fourth chapter is based onthe OFDM-ROF system, its basic model and description. Fifth chapter is PAPR and instantaneous power analysis. The effect of the envelope clipping on the peak-to-average power ratio (PAPR) and then instantaneous power of the band-limited OFDM signal is studied. While doing the PAPR analysis, the different approaches for the reduction of PAPR by different authors are compared. The sixth chapter is about the Signal distortion and channel capacity over additive white Gaussian noise and Rayleigh fading channels. The capacity calculations shown are based on the assumption that the distortion terms caused by the clipping are Gaussian. In the seventh chapter the ROF transmission performance is based on split-step Fourier method and nonlinear Schrödinger equation. The transmission performance is discussed from the measurement values by incorporating the spectral distribution of a modulation signal into the calculation of composite triple beats. The dynamic range of OFDM-64QAM which is evaluated from the calculations of Desired to Undesired Signal Ratio (DUR) is also presented. Thus, this project evaluates the OFDM-ROF system as a candidate for the future (4G) wireless system design.

In this paper, a novel constellation extension algorithm, named as peak-restricted constellation extension (PCE), is proposed for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) system. This algorithm actively selects outer constellation points which contribute to the large peak magnitudes, and dynamically alter the amplitudes of these points to reduce PAPR. It does not require transmitting any side information to the receiver and there is no loss in data rate. As radio-over-fiber (ROF) network is proved to be one of the best solutions for the wireless-access technology, this algorithm is verified in an OFDM-ROF system. It is shown that this algorithm significantly reduces the PAPR of OFDM signals. The performances of the system with and without the algorithm are also compared.

Radio-over-fiber (RoF) technology has several benefits such as larger bandwidth, reduced power consumption etc. that has made it an attractive implementation option for various communication systems including wireless LANs. This paper investigates the feasibility of orthogonal frequency division multiplexing (OFDM) as a modulation technique for a RoF based WLAN system in consistency with IEEE 802.11a. Results from a Matlab system model, which is consistent with the specifications of IEEE 802.11a, have been included to show the BER performance of the OFDM modulation technique. Next, the paper presents the results obtained from measuring several of the main factors affecting the performance of an OFDM system, including channel noise, multipath delay spread, power clipping, and synchronization requirements.

We propose an analytic technique, based on the Volterra series, to assess the impact of nonlinearities on the error probability of orthogonal frequency division multiplexing (OFDM) signals in radio over fibre (RoF) based wireless networks. We consider OFDM/BPSK signals and we determine the error probability of these signals in an illustrative RoF system, where either a semiconductor laser diode (SLD) or a Mach-Zehnder modulator (MZM) are used to generate these signals, with good agreement between analysis and simulation.

Discrete Wavelet Transform (DWT) based Multicarrier modulation (MCM) technique, namely Discrete Wavelet Multitone is a modified form of the Fourier Transform based Discrete Multitone (DMT) modulation technique, designated for wireline channels like DSL, Powerline, etc. DWMT has been recently proposed in order to overcome the drawbacks posed by DMT transceivers, such as inter-channel interference due to high side lobes, less spectral containment, use of cyclic prefixing, etc. The equalization issue with reference to DWMT is an active research area. We have analyzed the performance of a DWMT transceiver with time domain equalization techniques and compared it with DMT technique. Moreover this paper proposes the application of Overlap frequency domain equalization technique, and it is shown that Overlap-FDE gives same performance but with low complexity for the DSL channel.

In this paper, we consider out-of-band radiations caused by high sidelobes in orthogonal frequency division multiplexing (OFDM) system. Suppression of sidelobes in OFDM system allows higher spectral efficiency and less interference with existing legacy systems in OFDM based overlay system. We combine different sidelobe suppression techniques to suppress the sidelobes in OFDM system. The multiple-choice sequence (MCS) is combined with cancellation carriers (CCs) and also MCS is combined with subcarrier weighting (SW) technique. MCS is applied prior to CCs or SW techniques. Simulation results show that combining MCS with CCs and MCS with SW techniques the sidelobes in OFDM system can be significantly reduced, which allow a successful co-existance between OFDM overlay system and an existing legacy system.

Orthogonal Frequency Division Multiplexing (OFDM) transmissions are emerging as important modulation technique because of its capacity of ensuring high level robustness against interference. This paper presents a prototype of a high throughput and low complexity OFDM transceiver. OFDM is a modulation technique which is now widely used in various high speed mobile and wireless communication systems such as: fixed Wi-Fi system (IEEE 802.11a standard), mobile Wi-Fi system (IEEE 802.11b standard), fixed WiMAX system (IEEE 802.16a standard), and mobile WiMAX system (IEEE 802.16e standard). In this paper, the design and implementation of OFDM system will be illustrated. Moreover, the design and simulation results for some standards of OFDM using MATLAB will be observed as a practical system examples that uses OFDM as a modulation technique. All the proposed modules are designed using VHDL programming language. The transceiver is implemented on a Field-Programmable Gate Array (FPGA) through Xilinx System Generator for DSP. The proposed transceiver provides low processing latency. A rapid prototyping platform interfacing MATLAB with Xilinx kit is used in this development. Our experiments show that the proposed transceiver utilizes 68% of the slice LUTs and 55% of slice registers on Virtex-6 FPGA, operating at a maximum frequency of 112 MHz, which proof that our design have the lowest area over the previous related work presented before.

Orthogonal Frequency Division Multiplexing (OFDM) is the utmost widespread technology in wireless communications systems because of its orthogonality property, high spectral efficiency, and high data rates. It provides immunity to multipath fading and reduces Inter Symbol Interference (ISI). The tailback of OFDM is its high Peak to Average Power Ratio (PAPR), which distresses the dynamic range of HPA, introduces harmonics and large power back off required to minimize unsolicited harmonics. In this paper, an OFDM transceiver is implemented in LabVIEW with Universal Software Radio Peripheral (USRP), such that system complexity is less and BER performance is good. To reduce the PAPR, companding techniques are well-thought-out which include Square Root Companding (SQRT), Logarithmic Rooting (LogR) and Tangential Rooting Companding (TanhR). The performance of these techniques is analyzed and observed that TanhR reduces PAPR to 1.15 dB without degrading BER. OFDM is used in many wireless standards, including the 4G LTE downlink transmissions, DVB-T, WLAN. OFDM is also one of the prominent competing Multi Carrier Modulation (MCM) schemes for considering even for 5G wireless communications systems.

The peak-to-average raito (PAPR) in correlatively coded orthogonal frequency-division multiplexing (OFDM) system is studied. Correlative codes are proposed by large numbers of papers to significantly improve the spectral performance of OFDM with rectangular pulse. The large PAPR makes amplifier distort the signal before transmission and thus becomes one of the most serious drawbacks of OFDM. However, simulations illustrate that correlatively coded OFDM has much larger PAPR than uncoded OFDM. This makes its implementation very difficult. Selected mapping (SLM) is a promising PAPR reduction technique, which is distortionless and has good PAPR reducing performance. We use SLM to reduce the PAPR of correlatively coded OFDM, and prove that the very high spectral efficiency is not affected by the PAPR reduction. Simulations show that SLM can lower the PAPR of correlatively code OFDM efficiently without any loss of the spectral performance.

Orthogonal frequency division multiplexing (OFDM) is widely used in wireless systems because of its high spectral efficiency, though it is known that it is highly vulnerable to frequency synchronization errors, which severely impede its performance. Such errors arise due to carrier frequency offset and Doppler frequency spread. They destroy the orthogonality among sub carriers and introduce inter carrier interference (ICI). The interference power is proportional to the received signal strength and amount of frequency offset. Several proposal to reduce the impact of ICI in OFDM use very complex signal processing and some have associated bandwidth efficiency loss. Since ICI is inversely proportional to the sub carrier bandwidth, it is interesting to investigate the gains in a system with adaptable sub carrier bandwidth. A system which can support variable sub carrier bandwidths simultaneously meeting the needs of different ICI conditions is compared against a normal OFDM system which uses fixed carrier bandwidth (FSB). Results show that the VSB schemes can be preferred over FSB OFDM system when users with different receive signal strength and Doppler condition have to be served simultaneously.

Orthogonal frequency division multiplexing (OFDM) has been adopted in various wireless communication standards to exploit its high spectral efficiency and robustness against multipath fading channels. Along with the potential benefits of OFDM transmissions, a stringent requirement on orthogonality among subcarriers makes OFDM highly susceptible to synchronization errors, i.e., time and frequency offsets. Addressing the carrier frequency offset (CFO) estimation problem, the paper proposes a pilot-aided CFO estimation scheme for both coarse and fine carrier frequency synchronization in single-input single-output (SISO) OFDM receivers. By exploiting the maximum likelihood (ML) principle, the proposed ML-based CFO estimation algorithm functions properly over a wide range of CFO values and outperforms existing correlation-based schemes.

5G technology is the only hope that would let us bridge the tele-industry in terms of meeting the need with quality. It is estimated that there is a generation and usage of about 2.5*10^18 bytes per day. The statistics in the present day prove that the future needs will increase exponentially and so will the demand. Meeting these parameters like the data rates, speed for the users with current technologies like 3G, OFDM (Orthogonal Frequency Division Multiplexing) is quite impossible. It's high time that we leap up to another degree and unfold new methods to emerge into 5G-5TH Generation. Usage of appropriate modulating techniques and compatible devices would drive to the inception of a new era in the history of technology, which would be better than ever. The outright motto is to develop a waveform which holds high Spectral efficiency and minimal Peak to Average Power Ratio. The paper revolves around the Orthogonal Frequency Division Multiplexing (OFDM), Filter Bank Multicarrier (FBMC) and Universal Filtered Multicarrier (UFMC). These techniques are compared and analyzed on the basis of Spectral Efficiency, Bit Error Rate , PAPR by utilizing various subcarriers and modulation techniques. The results evidently prove that the spectral efficiency is quite insufficient in the case of OFDM. The existence of cyclic prefix adds to this constraint. FBMC and UFMC proves to be highly fictional and the drawbacks in the previous case are neutralized by the usage separate filters for each subcarriers which further increases the PAPR value. On advanced analysis we derive to conclusions that UFMC waveform technique is preferable for 5G on considering the value of PAPR. Optimization will add to the betterment of the situation. We would study the spectral efficiency, power spectral density, peak to average power ratio and performance in terms of bit error rate in practical senses.

System-on-a-chip (SoC) is now a trend in digital design because it gives a lot of advantages over discrete electronic based product such as higher speed, lower power consumption, smaller size, lower cost etc. Reconfigurable platforms such as FPGA, CPLD, and PLD are now being used for designing and implementing SoC due to their low cost, high capacity and tremendous speed. In this project single chip Orthogonal Frequency Division Multiplexing (OFDM) transmitter and receiver have been designed using Verilog HDL. OFDM is a multi carrier modulation technique used in the various digital communication systems like 3G GSM, WiMAX and LTE etc. The main advantage of this transmission technique is its robustness to channel fading in wireless communication environment. There are many applications of OFDM in communication such as digital audio broadcasting, Asynchronous Digital Subscriber Line (ADSL) and High bit-rate Digital Subscriber Line (HDSL) systems. In OFDM, two algorithms digital signal processing algorithm Fast Fourier transform (FFT) and Inverse Fast Fourier Transform (IFFT) are mainly involved. The 8-point IFFT/FFT Decimation-In-Frequency (DIF) with radix-2 algorithm has been analyzed and incorporated in the design. The design has been simulated on the FPGA platform with Altera's Quartus II simulator. Simulation results show that each of the modules of the proposed OFDM is working as desired. The test output achieved from the simulation result of the OFDM has been verified with that of the MATLAB output.