2.4 GHz Real-Time Prototyping Tool for OFDM Channel Estimation using USRP2 and LabVIEW

2019 ◽  
Vol 28 (14) ◽  
pp. 1950236
Author(s):  
Kerem Küçük
Keyword(s):  
Channel Estimation ◽  
Real Time ◽  
Software Defined Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Software Radio ◽  
Local Area ◽  
Estimation Methods ◽  
Wireless Receiver ◽  
Traffic Demand ◽  
The Real

Wireless local area networks (WLANs) are currently playing an important role in serving the indoor traffic demand. Therefore, there is a need for software-defined radio platforms (SDRs) that can enable the solutions used in these systems to be tested in real environments as well as simulated results. In this paper, we present the SDR-based wireless receiver platform for determining the real-time WLANs performance and provide the comparison of the different channel estimation methods for IEEE 802.11g based on orthogonal frequency division multiplexing (OFDM) operations. The implementation of the receiver comprises the universal software radio peripheral and National Instruments LabVIEW. To determine the real-time receiver tool performance, we emphasized necessary signal processing techniques and different channel estimation methods with varying experimental parameters in real wireless environments. Experimental results report that the SDR-based receiver tool with the LabVIEW in real-time provides the throughput of the OFDM wireless network. The captured throughput performance concerning frame error rate by the receiver is also scrutinized with different channel estimation methods.

scholarly journals Real-Time Data Transfer Based on Software Defined Radio Technique using Gnu radio/USRP

2019 ◽  
Vol 9 (1) ◽  
pp. 279-288
Keyword(s):  
Wireless Communication ◽  
Real Time ◽  
Software Defined Radio ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Software Radio ◽  
Spectrum Efficiency ◽  
Time Data ◽  
Real Time Data ◽  
Different Types

Software Defined Radio (SDR) offers a extensive radio communication platform that uses software updates to make use of fresh technology. From SDR, the idea of an Orthogonal frequency division multiplexing (OFDM) has evolved to personalize SDRs. The channel dispersiveness causes Inter Symbol Interference (ISI) but OFDM is more resistant at these condition because of this reason it is widely used in wireless communication systems. OFDM is having a good performance in terms of Bit Error Rate (BER) and high spectrum efficiency, so it is considered as a key role for next generation wireless communication system. In this paper, three different types of data are transferred in a real time SDR of OFDM transceiver using GNURadio/Universal Software Radio Peripheral (USRP). OFDM is extremely sensitive for synchronization errors such as time and frequency offsets and to estimate channel condition. Therefore, a standard algorithm is applied to solve synchronization and channel estimation problems in SDR based OFDM system. This testbed is implemented using two USRPs of model N210 as transmitter and receiver with an open source of GNURadio as a software. The implementation of OFDM is evaluated for different types of information like text, audio and Image. This evaluates the BER v/s SNR for real time data transmission in SDR Environment

scholarly journals A Comprehensive Review on Channel Estimation in OFDM System

2019 ◽  
Vol 5 (3) ◽  
pp. 6 ◽  
Author(s):  
Neha Dubey ◽  
Ankit Pandit
Keyword(s):  
Channel Estimation ◽  
Mean Square Error ◽  
Orthogonal Frequency Division Multiplexing ◽  
Transmission Rate ◽  
Minimum Mean Square Error ◽  
Estimation Method ◽  
Least Square ◽  
Estimation Methods ◽  
Mean Square ◽  
Mimo Ofdm

In wireless communication, orthogonal frequency division multiplexing (OFDM) plays a major role because of its high transmission rate. Channel estimation and tracking have many different techniques available in OFDM systems. Among them, the most important techniques are least square (LS) and minimum mean square error (MMSE). In least square channel estimation method, the process is simple but the major drawback is it has very high mean square error. Whereas, the performance of MMSE is superior to LS in low SNR, its main problem is it has high computational complexity. If the error is reduced to a very low value, then an exact signal will be received. In this paper an extensive review on different channel estimation methods used in MIMO-OFDM like pilot based, least square (LS) and minimum mean square error method (MMSE) and least minimum mean square error (LMMSE) methods and also other channel estimation methods used in MIMO-OFDM are discussed.

scholarly journals Projection wavelet weighted twin support vector regression for OFDM system channel estimation

2020 ◽  
Author(s):  
Lidong Wang ◽  
Yimei Ma ◽  
Xudong Chang ◽  
Chuang Gao ◽  
Qiang Qu ◽  
...  
Keyword(s):  
Channel Estimation ◽  
Support Vector Regression ◽  
Orthogonal Frequency Division Multiplexing ◽  
Channel Model ◽  
Wireless Channel ◽  
Estimation Methods ◽  
Support Vector ◽  
Ofdm System ◽  
Twin Support Vector Regression ◽  
Empirical Risk

Abstract In this paper, an efficient projection wavelet weighted twin support vector regression (PWWTSVR) based orthogonal frequency division multiplexing system (OFDM) system channel estimation algorithm is proposed. Most Channel estimation algorithms for OFDM systems are based on the linear assumption of channel model. In the proposed algorithm, the OFDM system channel is consumed to be nonlinear and fading in both time and frequency domains. The PWWTSVR utilizes pilot signals to estimate response of nonlinear wireless channel, which is the main work area of SVR. Projection axis in optimal objective function of PWWRSVR is sought to minimize the variance of the projected points due to the utilization of a priori information of training data. Different from traditional support vector regression algorithm, training samples in different positions in the proposed PWWTSVR model are given different penalty weights determined by the wavelet transform. The weights are applied to both the quadratic empirical risk term and the first-degree empirical risk term to reduce the influence of outliers. The final regressor can avoid the overfitting problem to a certain extent and yield great generalization ability for channel estimation. The results of numerical experiments show that the propose algorithm has better performance compared to the conventional pilot-aided channel estimation methods.

scholarly journals A Novel Noise Suppression Channel Estimation Method Based on Adaptive Weighted Averaging for OFDM Systems

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 997 ◽  
Author(s):  
Zhang ◽  
Zhou ◽  
Wang
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Noise Suppression ◽  
Estimation Method ◽  
Weighted Averaging ◽  
Doppler Spread ◽  
Estimation Methods ◽  
Ofdm Systems

Orthogonal frequency division multiplexing (OFDM) systems have inherent symmetric properties, such as coding and decoding, constellation mapping and demapping, inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) operations corresponding to multi-carrier modulation and demodulation, and channel estimation is a necessary module to resist channel fading in the OFDM system. However, the noise in the channel will significantly affect the accuracy of channel estimation, which further affects the recovery quality of the final received signals. Therefore, this paper proposes an efficient noise suppression channel estimation method for OFDM systems based on adaptive weighted averaging. The basic idea of the proposed method is averaging the last few channel coefficients obtained from coarse estimation to suppress the noise effect, while the average frame number is adaptively adjusted by combining Doppler spread and signal-to-noise ratio (SNR) information. Meanwhile, to better combat the negative effect brought by Doppler spread and inter-carrier interference (ICI), the proposed method introduces a weighting factor to correct the weighted value of each frame in the averaging process. Simulation results show that the proposed channel estimation method is effective and provides better performance compared with other conventional channel estimation methods.

scholarly journals Research on Optimized Control Model of Freeway Based on Dynamic Traffic Demand Estimation

2014 ◽  
Vol 6 ◽  
pp. 797293 ◽  
Author(s):  
Zhu Jiang ◽  
Shubin Li
Keyword(s):  
Optimal Control ◽  
Real Time ◽  
Demand Estimation ◽  
Control Model ◽  
Control Module ◽  
Traffic Demand ◽  
The Real ◽  
Traffic Conditions ◽  
Real Time Traffic ◽  
Global Optimal

According to the estimation information of dynamic traffic demands, a novel optimal control model of freeway was established on the basis of the hierarchical concept. There are four control modules in this model. The OD prediction module predicts the total traffic demands in a long time and determines the upper bound of the future queuing length in advance; the global optimal control module predicts the future traffic state and establishes the coordination constraints for each ramp in the network; the traffic demand estimation module estimates the real-time traffic conditions for each ramp; the local adaptive control module regulates ramp metering rate according to the estimated information of the real-time traffic conditions and the results optimized by the global optimal control module. The simulation results show that this control system is of a good dynamic performance. It coordinates the benefits of various ramps and optimizes the overall performance of the freeway network.

scholarly journals Wireless channel estimation in OFDM systems based on collaborative filtering techniques

2019 ◽  
Vol 70 (3) ◽  
pp. 244-252
Author(s):  
Velimir Švedek ◽  
Adrian Satja Kurdija ◽  
Željko Ilić
Keyword(s):  
Channel Estimation ◽  
Collaborative Filtering ◽  
Orthogonal Frequency Division Multiplexing ◽  
Predictive Accuracy ◽  
Spline Interpolation ◽  
Estimation Algorithm ◽  
Wireless Channel ◽  
Estimation Methods ◽  
Ofdm Systems ◽  
Interpolation Methods

Abstract In this paper, a new channel estimation algorithm in Orthogonal Frequency Division Multiplexing (OFDM) systems is proposed. The proposed algorithm is suitable for cases with low density of pilot sub-carriers, where standard interpolation methods (linear, second order and cubic spline interpolation) are inaccurate. The algorithm improves the interpolation methods by employing memory based collaborative filtering (CF) techniques which are less sensitive to the number and location of the pilot subcarriers. CF algorithms are usually used in the context of recommender systems (e-commerce) for predictions of the unknown user-item ratings based on known values of similar users. The advantage of CF is the ability to e ciently produce quality predictions with highly sparse data. Computer simulations are used to verify the proposed channel estimation algorithm and demonstrate that the proposed algorithm improves predictive accuracy metrics, such as Root Mean Squared Error (RMSE), compared to usual estimation methods.

scholarly journals Channel Estimation Based on Statistical Frames and Confidence Level in OFDM Systems

2018 ◽  
Vol 8 (9) ◽  
pp. 1607 ◽  
Author(s):  
Xiao Zhou ◽  
Chengyou Wang ◽  
Ruiguang Tang ◽  
Mingtong Zhang
Keyword(s):  
Channel Estimation ◽  
Mean Square Error ◽  
Confidence Level ◽  
Orthogonal Frequency Division Multiplexing ◽  
Minimum Mean Square Error ◽  
Estimation Method ◽  
Least Square ◽  
Estimation Methods ◽  
Mean Square ◽  
Inverse Operation

Channel estimation is an important module for improving the performance of the orthogonal frequency division multiplexing (OFDM) system. The pilot-based least square (LS) algorithm can improve the channel estimation accuracy and the symbol error rate (SER) performance of the communication system. In pilot-based channel estimation, a certain number of pilots are inserted at fixed intervals between OFDM symbols to estimate the initial channel information, and channel estimation results can be obtained by one-dimensional linear interpolation. The minimum mean square error (MMSE) and linear minimum mean square error (LMMSE) algorithms involve the inverse operation of the channel matrix. If the number of subcarriers increases, the dimension of the matrix becomes large. Therefore, the inverse operation is more complex. To overcome the disadvantages of the conventional channel estimation methods, this paper proposes a novel OFDM channel estimation method based on statistical frames and the confidence level. The noise variance in the estimated channel impulse response (CIR) can be largely reduced under statistical frames and the confidence level; therefore, it reduces the computational complexity and improves the accuracy of channel estimation. Simulation results verify the effectiveness of the proposed channel estimation method based on the confidence level in time-varying dynamic wireless channels.

scholarly journals Enhancing Mobility Based on Realistic Models for Vehicular Ad Hoc Networks

2021 ◽  
Vol 10 (4) ◽  
pp. 220-227
Author(s):  
Hariharasudhan V. ◽  
Vetrivelan P*
Keyword(s):  
Real Time ◽  
Vehicular Ad Hoc Networks ◽  
Network Reliability ◽  
Realistic Model ◽  
Mobility Model ◽  
Communication Link ◽  
Communication Model ◽  
Mobility Models ◽  
Traffic Demand ◽  
The Real

Creation and maintaining of the one-to-one communication link between the nodes in Vehicular Adhoc Networks are challenging. The model which is very much efficient for one particular scenario will not work at the same level of efficiency for another environment. The mobility of the nodes in the network plays a crucial role in establishing a reliable communication model in the VANETs. Analyzing the nature of mobility inside a particular network based on logical and historical data paves an efficient way in the routing of packets by predicting the best route and improve the quality of the network, reliability, and other performance in terms of serviceability. This paper aims to analyze the drawbacks of existing mobility models utilizing various network quality parameters by classifying them into microscopic and macroscopic mobility models. With the insight gained from the analysis, we propose two methodologies where the realistic model for the VANETs can be established. The models are architected with the help of the information provided by the Geographic information system. The conventional mobility models include excessive details such as road and street layouts, intersection with traffic signals, acceleration and deceleration, building, and other obstacles in a realistic mobility model, that requires prolonged time to design and optimize, it should complicate the simulation. Designing an effective, realistic mobility model is crucial. The key objectives of this proposal are to architect realistic VANETs mobility models by taking into account the real-time road environment and actual data according to the traffic demand and improving the real-time performance of VANETs

scholarly journals 5G F-OFDM Waveform Based Software-Defined Radio Technology

2021 ◽  
Vol 20 ◽  
pp. 68-80
Author(s):  
Dia Mohamad Ali ◽  
Zhraa Zuheir Yahya
Keyword(s):  
Software Defined Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Hardware Implementation ◽  
Software Radio ◽  
Spectrum Efficiency ◽  
Practical Implementation ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Fifth Generation ◽  
Radio Technology

Filtered-orthogonal frequency division multiplexing (F-OFDM) is a quasi-orthogonal waveform candidate for the applications of the fifth generation (5G) communication system. In this study, an F-OFDM waveform with unequal sub-band sizes is proposed to improve the spectrum efficiency (SE) of the 5G system. The proposed waveform is modeled with the Blackman window-sinc filter and is developed based on the software-defined radio (SDR) technology for practical implementation. The result shows that the F-OFDM performance of the simulation and hardware implementation is approximately the same. The SE using the proposed F-OFDM waveform is 6% and 5.8% higher than the SE using the conventional OFDM waveform under the simulation in the LabVIEW NXG simulator and under the practical use in the universal software radio peripheral (USRP) platform, respectively.

Sign in / Sign up

Export Citation Format

Share Document