Orthogonal Frequency Division Multiplexing (OFDM) is a method of encoding digital data on multiple carrier frequencies. It has become a prevalent technique for wideband digital communication. Forward Error Correction ...
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ISBN:
(纸本)9781509007745
Orthogonal Frequency Division Multiplexing (OFDM) is a method of encoding digital data on multiple carrier frequencies. It has become a prevalent technique for wideband digital communication. Forward Error Correction (FEC) schemes for OFDM communication system is presented in this paper. Interleaver is a vital part in the communication system design. Matrix interleaver implementation which significantly improves the Bit Error Rate (BER) performance over other interleaver designs is proposed. Simulation and analysis of OFDM communication system is carried out with reference to IEEE 802.16 WiMAX standard. Four FEC schemes were developed from the combinations of convolutional encoding and interleaving. The BER performance analysis and comparison of four different FEC schemes are obtained. Among them, the single convolutional coding and dual interleaving performs the best under all ranges of Signal to Noise Ratio (SNR).
Research results are shown and noise immunity estimation is done for based on OFDM technolo*, tropospheric systems, with usage of the noise immunity of classical OFDM systems for mobile application. A modeling in MATL...
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ISBN:
(纸本)9781479985470
Research results are shown and noise immunity estimation is done for based on OFDM technolo*, tropospheric systems, with usage of the noise immunity of classical OFDM systems for mobile application. A modeling in MATLAB and LabVIEW PXI and an experimental test with error probability evaluation are performed. Investigation possibilities to tropospheric OFDM systems are estimated and proposed. System modules possible.
An analytical approach is presented to determine the impact of time selective fading, tinting jitter and AWGN on a STBC-OFDM system with DQPSK, DPSK and QPSK modulation schemes. The BER performance results are evaluat...
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ISBN:
(纸本)9781424418282
An analytical approach is presented to determine the impact of time selective fading, tinting jitter and AWGN on a STBC-OFDM system with DQPSK, DPSK and QPSK modulation schemes. The BER performance results are evaluated for different values of fading and jitter variance in presence of single and multiple receiving antennas. The computed results show that the DPSK and QPSK systems suffer higher amount of power penalty than DQPSK system due to the jitter effect. Performance improvement due to application of convolution coding is also reported.
In this paper, we investigate the performance of frequency domain equalization in conjunction with Soft Decision (SD) Viterbi decoding in the Orthogonal Frequency Division Multiplexing (OFDM) systems. Specifically, we...
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ISBN:
(纸本)9781467300407
In this paper, we investigate the performance of frequency domain equalization in conjunction with Soft Decision (SD) Viterbi decoding in the Orthogonal Frequency Division Multiplexing (OFDM) systems. Specifically, we compare the performance of two frequency domain equalization methods, one using complete phase and magnitude equalization of complex Quadrature Amplitude Modulated (QAM) symbols, while the other using only-phase equalization, or constellation rotation. Our investigation shows that the OFDM system using only-phase equalization in conjunction with soft decision decoding for convolutional codes has a better performance of about 2.5-4 dB in multipath environment than the system implementing complete equalization with the same soft decision decoding at 10(-4) BER level.
An efficient and hardware economic channel coding technique is essential in todays high-speed mobile communication systems. The channel coding parameters will have a large impact on the system performance (data rate a...
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ISBN:
(纸本)0780385217
An efficient and hardware economic channel coding technique is essential in todays high-speed mobile communication systems. The channel coding parameters will have a large impact on the system performance (data rate and bit error rate) and also on the hardware development in terms of area consumption and timing behaviour. Therefore, important system parameters like Code Rate, Constraint Length and Viterbi Decoding Strategy (Single State or Best State and the resulting truncation depth for both strategies) have to be decided early in the design How. The objective of this paper is to discuss the technical tradeoff (system performance and hardware cost) when choosing the channel coding parameters for a system with convolutional encoding and Viterbi decoding. For a wide range of possible channel coding parameters the impact on the system performance and on hardware consumptions,, which have been acquired from Field Programmable Gate Array (FPGA) implementations', will be discussed and compared.
This paper presents a new pre-processing approach for convolutional codes that can provide the adaptive capability to a standard Viterbi decoder. By identifying and generating the decoded data from the zero Hamming di...
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ISBN:
(纸本)9781424414833
This paper presents a new pre-processing approach for convolutional codes that can provide the adaptive capability to a standard Viterbi decoder. By identifying and generating the decoded data from the zero Hamming distance path, all computations in the Viterbi decoder can be avoided. This makes it possible to stop the Viterbi decoder in real time as long as no error occurs in the received code words;the Viterbi decoder is restarted to correct errors otherwise. With this approach, significant power, i.e. 97% of a standard Viterbi decoder power dissipation, can be saved when the Eb/No is as low as 13dB.
Radiated interference environments can significantly degrade the performance of the digital communication systems that are widely used today. Problems from such inter-system interference might need to be analyzed befo...
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ISBN:
(纸本)9781479966165
Radiated interference environments can significantly degrade the performance of the digital communication systems that are widely used today. Problems from such inter-system interference might need to be analyzed beforehand or as problems occur. Another application where such analysis is of interest is in systems using dynamic allocation of spectrum, where it serves as basis for spectrum allocation. To be useful in on-line applications, the analysis method should be fast and of low complexity. A common method is therefore to approximate the interference as Additive White Gaussian Noise, AWGN. However, if the noise is impulsive, this approximation can cause large errors in Bit Error Probability (BEP) estimation. It is desirable to avoid both under-and overestimations. Underestimations can lead to interference problems in the application, while overestimating could cause expensive protection measures to be used unnecessarily. One type of systems that have not received much interest regarding error estimation are those using both error correcting codes and direct sequence spread sprectrum, DSSS. Two systems using this combination are the third generation mobile telephony standard 3G UMTS, and the global navigation systems GPS and Galileo. In this paper we derive necessary conditions for when the Gaussian approximation can be used accurately for impulsive interference, in a DSSS system using convolutional coding.
Robot ego-noise, that is the noise produced while the robot is moving around, can carry useful information about the motor system and the embodiment of the agent. We present an experiment where a mobile robot acquires...
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ISBN:
(纸本)9781538637159
Robot ego-noise, that is the noise produced while the robot is moving around, can carry useful information about the motor system and the embodiment of the agent. We present an experiment where a mobile robot acquires knowledge about its ego-noise. In particular, we adopt a learning strategy based on self-exploration behaviours and on an inverse model for encoding the mappings between ego-noise and the motor commands that produced it. A convolutional Autoencoder is adopted for semi-supervised learning of auditory features. The inverse model maps both auditory features and perception of the robot speed to the motor commands that produced the ego-noise. We demonstrate how the trained models can be used for imitating movements from listening to the noise they produce.
In this paper we describe ensemble of Low-Density Parity-Check (LDPC) block codes based on Partial Unit Memory (P) UM codes. We study a decoding performance of received ensemble in the case of different parameters of ...
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ISBN:
(纸本)9781479940509
In this paper we describe ensemble of Low-Density Parity-Check (LDPC) block codes based on Partial Unit Memory (P) UM codes. We study a decoding performance of received ensemble in the case of different parameters of constituent LDPC codes. The results of simulation of obtained code constructions for an iterative "belief propagation" (Sum-Product) decoding algorithm, applied in the case of transmission of a code word via a binary channel with an additive Gaussian white noise and BPSK modulation, are presented.
Passive optical network based on orthogonal frequency division multiplexing (OFDM-PON) exhibits excellent performance in optical access networks due to its greater resistance to fiber dispersion, high spectral efficie...
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ISBN:
(纸本)9780819499202
Passive optical network based on orthogonal frequency division multiplexing (OFDM-PON) exhibits excellent performance in optical access networks due to its greater resistance to fiber dispersion, high spectral efficiency and flexibility on both multiple services and dynamic bandwidth allocation. The major elements of conventional OFDM communication system are two-dimensional (2-D) signal mapper and one-dimensional (1-D) inverse fast fourier transform (IFFT). Three dimensional (3-D) OFDM use the concept of 3-D signal mapper and 2-D IFFT. With 3-D OFDM, minimum Euclidean distance (MED) is increased which results in BER performance improvement. As bit error rate (BER) depends on minimum Euclidean distance (MED) which is 15.46 % more in case of 3-D OFDM as compared to 2-D OFDM. Forward error correction (FEC) coding is a technique where redundancy is added to original bit sequence to increase the reliability of communication system. In this paper, we propose and analytically analyze a new PON architecture based on 3-D OFDM with convolutional coding and Viterbi decoding and is compared with conventional 2-D OFDM under various system impairments for coherent optical orthogonal frequency division multiplexing (CO-OFDM) without using any optical dispersion compensation. Analytical result show that at BER of 10-9, there is 2.7 dB, 3.8 dB and 9.3 dB signal-to-noise ratio (SNR) gain with 3-D OFDM, 3-D OFDM combined with convolutional coding and Viterbi hard decision decoding (CC-HDD) and 3-D OFDM combined with convolutional coding and Viterbi soft decision decoding (CC-SDD) respectively as compared to 2-D OFDM-PON. At BER of 10-9, 3-D OFDM-PON with CC-HDD gives 2.8 dB improvement in optical budget for both upstream and downstream path and gives 5.7 dB improvement in optical budget using 3-D OFDM-PON combined with CC-SDD as compared to conventional OFDM-PON system.
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