Perceptron Algorithm for Channel Shortening in OFDM System with Multipath Fading Channels

2014 ◽  
Author(s):  
Mohammad Alizadeh ◽  
Saeed Ghazi-Maghrebi ◽  
Amir Atashbar
Keyword(s):  
Fading Channels ◽  
Multipath Fading ◽  
Ofdm System ◽  
Channel Shortening ◽  
Multipath Fading Channels ◽  
Perceptron Algorithm

scholarly journals Performance of OFDM System under Different Fading Channels and Channel Coding

2017 ◽  
Vol 6 (1) ◽  
pp. 54-61
Author(s):  
Pratima Manhas ◽  
M. K. Soni
Keyword(s):  
Fading Channels ◽  
Channel Coding ◽  
Orthogonal Frequency Division Multiplexing ◽  
Mobile Station ◽  
Multipath Fading ◽  
Ofdm System ◽  
Angle Of Arrival ◽  
Multiple Reflections ◽  
Multipath Fading Channels ◽  
Base Transceiver Station

Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier modulation (MCM) technique in which larger bandwidth is divided into parallel narrow bands each of which is modulated by different subcarriers. All the subcarriers are orthogonal to each other and hence it reduces the interference among various subcarriers. OFDM technique is an efficient modulation technique used in certain wired and wireless application.In a wireless communication channel, the transmitted signal can travel from transmitter to receiver over multiple reflective paths. This results to multipath fading which causes fluctuations in amplitude, phase and angle of arrival of the received signal. For example, the signal which is transmitted from BTS (base transceiver station) may suffer multiple reflections from the buildings nearby, before reaching the mobile station. Such multipath fading channels are classified into slow fading/fast fading and frequency-selective/flat fading channels. This paper discusses the performance of OFDM system using various fading channels and channel coding. The parameter which is known as Bit error rate (BER) is calculated under different fading channels (AWGN, Rayleigh and Rician) for different digital modulation (BPSK, QPSK and QAM) and Channel coding (linear/Cyclic coding). Matlab Simulink tool is used to calculate the BER parameter.

An Improved DFT-Based Channel Estimation Algorithm for OFDM System on Time-Varying Multipath Fading Channels

2014 ◽  
Vol 989-994 ◽  
pp. 3786-3789 ◽  
Author(s):  
Xin Li Ma ◽  
Tong Liang Fan ◽  
Yong Feng Du
Keyword(s):  
Channel Estimation ◽  
Fading Channels ◽  
Estimation Algorithm ◽  
Multipath Fading ◽  
Statistical Information ◽  
Time Varying ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Multipath Fading Channels ◽  
Suppress Noise

An improved discrete Fourier transform DFT-based channel estimation for OFDM systems is proposed. Conventional DFT-based channel estimator improved its performance by suppressing noise, but it does not completely suppress noise. In order to overcome the disadvantage, this paper proposed a gate method without requiring any channel statistical information. This method comprehensively considersthe effects of the power of the strongest path and the noises. Computer simulation demonstrates the performance of the proposed algorithms in terms of bit error rate.

Comparison of various channel equalization techniques in OFDM system using different digital modulations

2016 ◽  
Vol 3 (3) ◽  
pp. 634 ◽  
Author(s):  
Pratima Manhas ◽  
M.K. Soni
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Ofdm System ◽  
Multipath Fading Channels ◽  
Estimation Algorithms ◽  
High Data ◽  
Data Rates ◽  
High Data Rates

<p>The nature of future wireless applications requires high data rates and for this OFDM technique is used. OFDM stands for orthogonal frequency division multiplexing and is a type of multi-carrier transmission where all the subcarriers are orthogonal to each other. At high data rates, the channel distortion to the data is very important and it is somewhat impossible to recover the transmitted data with a simple receiver. So a complex receiver structure is needed which uses computationally expensive equalization and channel estimation algorithms to estimate the channel. These estimations can be used within the received data to recover the originally transmitted data. OFDM can simplify the equalization problem by changing the frequency-selective channel into a flat channel. The radio channels in mobile radio systems are usually multipath fading channels that results in intersymbol interference (ISI) in the received signal. To remove ISI from the signal, many kind of equalizers can be used. The need for equalizers arises from the fact that the channel has amplitude and phase dispersion which results in the interference of the transmitted signals with one another which is known as ISI .So, to solve this problem equalizers are designed. Equalizer is intend to work in such a way that Bit Error Rate (BER) should be low and Signal-to-Noise Ratio (SNR) should be high. An equalizer within a receiver compensates for the average range of expected channel amplitude and delay characteristics. This paper deals with the various equalization techniques (LMS, RLS and CMA) used for OFDM system .A comparative analysis of different equalization technique in terms of BER is done using MATLAB Simulink.</p>

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