Performance Improvement Of OOFDM Systems Based On Advanced Logarithmic Companding Technique (original) (raw)
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Comparative performance of OM-OFDM in broadband systems
Electronics Letters, 2012
A method called offset modulation (OM-OFDM) is proposed to control the peak-to-average power ratio (PAPR) of an OFDM signal. The authors demonstrate the significant modulation, structural and performance differences between an OM-OFDM and CE-OFDM method. The OM-OFDM method in addition is able to accurately control the PAPR of a transmission for a targeted BER, which is currently not possible with CE-OFDM. By using a power performance decision metric (D), the OM-OFDM method is shown to offer a 34 dB and 3.44 dB net power performance gain (at a BER of 10 −4) when compared to a CE-OFDM and traditional OFDM transmission for frequency selective fading channel conditions, respectively.
Performance Improvement for Optical OFDM Systems Using Symbol Time Compression
Visible light communication (VLC) is now used to achieve high data rates. Optical-orthogonal frequency division multiplexing (O-OFDM) is a strong technique for intensity modulation and direct detection (IM-DD). Direct current biased O-OFDM (DCO-OFDM) and asymmetrically clipped O-OFDM are two modern O-OFDM systems that operate with IM-DD constraints (ACO-OFDM). Due to severe out of band interference, the DCO-OFDM and ACO-OFDM systems have a high peak to average power ratio (PAPR) and substantial adjacent channel interference (ACI) (OOB). Furthermore, as compared to bipolar OFDM systems, they obtain a greater chance of bit error. The combination of the STC scheme, symbol extension, and pulse shaping signal is presented in this paper for improving the performance of the O-OFDM system without affecting system throughput. This article also decreases the OOB, PAPR, and bit error rate (BER) of DCO-OFDM and ACO-OFDM systems. Further analytical analyses for the proposed systems, such as OOB,...
On the Performance of Different OFDM Based Optical Wireless Communication Systems
Journal of Optical Communications and Networking, 2011
This paper analyzes the performance of indoor orthogonal frequency division multiplexing (OFDM) optical wireless communication systems in the presence of light emitting diode (LED) nonlinear distortions. There are several forms of optical OFDM using intensity modulation [7th Int. Symp. on Communication Systems Networks and Digital Signal Processing (CSNDSP), 2010, pp. 566-570]. In this paper, DC-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM) are considered. ACO-OFDM produces a half-wave symmetry time signal at the output of the OFDM modulator by special assignment of subcarriers, thus allowing signal clipping at the zero level and avoiding the need for DC bias at the expense of data rate reduction. DCO-OFDM assigns data to all possible subcarriers to increase the data rate. However,
Logarithmic Companding for PAPR Reduction in OFDM
Orthogonal Frequency Division Multiplexing (OFDM) is taken into account to be a promising technique against the multipath attenuation channel for wireless communications. However, OFDM faces the Peak-to-Average Power magnitude relation (PAPR) downside that's a significant downside of multicarrier gear that results in power unskillfulness in RF section of the transmitter. This paper gift completely different PAPR reduction techniques ANd conclude an overall comparison of those techniques. we have a tendency to additionally simulate the chosen mapping technique (SLM) for various route range that is most effective technique for PAPR reduction once the amount of subcarrier is massive. Simulation shows that the PAPR downside reduced because the route range will increase. Keywords: Orthogonal Frequency Division Multiplexing (OFDM), Peak-to-Average Power Ratio (PAPR), Power Amplifiers (PAs), Selected Mapping (SLM), Complementary Cumulative Distribution Function (CCDF)
Orthogonal Frequency Division Multiplexing (OFDM) is taken into account to be a promising technique against the multipath attenuation channel for wireless communications. However, OFDM faces the Peak-to-Average Power magnitude relation (PAPR) downside that's a significant downside of multicarrier gear that results in power unskillfulness in RF section of the transmitter. This paper gift completely different PAPR reduction techniques ANd conclude an overall comparison of those techniques. we have a tendency to additionally simulate the chosen mapping technique (SLM) for various route range that is most effective technique for PAPR reduction once the amount of subcarrier is massive. Simulation shows that the PAPR downside reduced because the route range will increase.
REDUCTION OF PEAK TO AVERAGE POWER RATIO OF OFDM SIGNALS USING COMPANDING
In this paper, the use of companding as an effective tool for minimizing the peak-to-average power ratio (PAPR) of OFDM signals is presented. The influence of in-band and out-of band noise due to sampling and compression is considered. The bit-error-rate (BER) performance for different companding profiles is also evaluated for transmissions within an A WGN channel. The improvement on BER performance and P APR is studied for various companding profiles and is compared with the performance due to clipping within the OFDM transmissions.
PERFORMANCE ANALYSIS OF OPTICAL OFDM SYSTEM USING PM
TJPRC, 2014
As the demand of new wireless telephony applications grow exponentially and interest in discovering various methods to combat interference and provide solutions broadband wired and wireless communication system. Orthogonal frequency division multiplexing (OFDM) is considered to as one of the promising solution for such applications as well as a strong contestant modulation technique for fiber optical communication. This paper highlights multi-dimensional while considering fiber optic communication with OFDM. To achieve good performance in optical systems, OFDM must be adapted in various ways. This paper gives the performance analysis of optical orthogonal frequency division multiplexing using phase modulation (PM) technique with optical fiber link. Our study shows that as the length of the fiber increases the distortion also increases. This distortion can be decreased with the help of Raman amplifier.
Pilot-Assisted PAPR Reduction Technique for Optical OFDM Communication Systems
Journal of Lightwave Technology, 2000
This paper investigates the use of a pilot signal in reducing the electrical peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) intensitymodulated optical wireless communication system. The phase of the pilot signal is chosen based on the selected mapping (SLM) algorithm while the maximum likelihood criterion is used to estimate the pilot signal at the receiver. Bit error rate (BER) performance of the pilot-assisted optical OFDM system is identical to that of the basic optical OFDM (with no pilot and no PAPR reduction technique implemented) at the desired BER of less than < 10 −3 needed to establish a reliable communication link. The pilot-assisted PAPR reduction technique results in higher reduction in PAPR for high order (M > 4) constellations than the classical SLM. With respect to a basic OFDM system, with no pilot and no PAPR reduction technique implemented, a pilot-assisted M -QAM optical OFDM system is capable of reducing the electrical PAPR by over about 2.5 dB at a modest complementary cumulative distribution function (CCDF) point of 10 −4 for M = 64. Greater reductions in PAPR are possible at lower values of CCDF with no degradation to the system's error performance. Clipping the time domain signal at both ends mildly (at 25 times the signal variance level) results in a PAPR reduction of about 6.3 dB at the same CCDF of 10 −4 but with an error floor of about 3 × 10 −5 . Although it is possible to attain any desired level of electrical PAPR reduction with signal clipping, this will be at a cost of deterioration in the systems's bit error performance.