scholarly journals Training Based Channel Estimation for Multitaper GFDM System

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Shravan Kumar Bandari ◽  
Venkata Mani Vakamulla ◽  
A. Drosopoulos
Keyword(s):  
Channel Estimation ◽  
Pulse Shaping ◽  
Minimum Mean Square Error ◽  
Computational Cost ◽  
Estimation Methods ◽  
Frequency Division ◽  
Prolate Spheroidal ◽  
Prototype Filter ◽  
Key Features ◽  
Simulation Results

Recent activities in the cellular network world clearly show the need to design new physical layer waveforms in order to meet future wireless requirements. Generalized Frequency Division Multiplexing (GFDM) is one of the leading candidates for 5G and one of its key features is the usage of circular pulse shaping of subcarriers to remove prototype filter transients. Due to the nonorthogonal nature of the conventional GFDM system, inherent interference will affect adversely channel estimation. With Discrete Prolate Spheroidal Sequences (DPSSs) or multitapers as prototype filters an improved orthogonal GFDM system can be developed. In this work, we investigate channel estimation methods for multitaper GFDM (MGFDM) systems with and without Discrete Fourier Transform (DFT). The simulation results are presented using Least Squares (LS) and Minimum Mean Square Error (MMSE) channel estimation (CE) methods. DFT based CE methods provide better estimates of the channel but with an additional computational cost.

scholarly journals Channel Estimation and Peak-to-Average Power Ratio Analysis of Narrowband Internet of Things Uplink Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Md Sadek Ali ◽  
Yu Li ◽  
Md Khalid Hossain Jewel ◽  
Oluwole John Famoriji ◽  
Fujiang Lin
Keyword(s):  
Internet Of Things ◽  
Channel Estimation ◽  
Communication Systems ◽  
Power Efficiency ◽  
Pulse Shaping ◽  
Minimum Mean Square Error ◽  
Average Power ◽  
Estimation Methods ◽  
Area Network ◽  
Power Ratio

Narrowband Internet of Things (NB-IoT) is a cellular based promising low-power wide-area network (LPWN) technology standardized by the 3rd Generation Partnership Project (3GPP) in release-13 as a part of the future 5th Generation (5G) wireless communication systems. The main design target of NB-IoT was to enhance radio coverage by repeating signal over an additional period of time for the ultralow-end IoT devices that would be operated in extreme coverage environments. But the power efficiency of the low-cost NB-IoT user equipment (NB-IoT UE) in the uplink is the major concern. Coverage improvement from signal repetitions depends on the channel estimation quality at extremely bad radio conditions. The typical operating signal-to-noise ratio (SNR) for NB-IoT is expected to be much lower than the zero. In this paper, we have proposed two efficient narrowband demodulation reference signal (NDMRS)-assisted channel estimation algorithms based on the conventional least squares (LS) and minimum mean square error (MMSE) estimation methods. The theoretical analysis and the link-level performance of our proposed estimation methods are presented. Simulation results exhibit that the proposed methods provide better estimation precision compared to the traditional LS and MMSE methods at the low SNR situations. Furthermore, we have analyzed the raised-cosine (RC) and square-root-raised cosine (RRC) pulse shaping to reduce peak-to-average power ratio (PAPR) as an uplink transmit filter. The PAPR values are evaluated through extensive computer simulations for both single-tone and multi-tone transmissions. Our evaluation results vindicate that the RRC pulse shaping with lower PAPR values is feasible to design of practical NB-IoT uplink transmitter and increases power efficiency.

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.

Performance of OQAM/GFDM in Spatial Multiplexing MIMO Systems

2020 ◽  
Vol 11 (2) ◽  
pp. 39-57
Author(s):  
Simon Wissam Tarbouche ◽  
Abdel-Nasser Assimi
Keyword(s):  
Interference Cancellation ◽  
Pulse Shaping ◽  
Matched Filter ◽  
Mimo Systems ◽  
Mimo System ◽  
Spatial Multiplexing ◽  
Frequency Division ◽  
Fifth Generation ◽  
Additional Processing ◽  
Simulation Results

Generalized frequency division multiplexing (GFDM) is a prominent candidate to be used by the mobile Fifth Generation (5G) physical layer. Nevertheless, the integration of GFDM with Spatial Multiplexing (SM) MIMO system is essential to fulfill the data rate requirements. SM detection of MIMO-GFDM becomes a more challenging topic because of ICI and ISI due to the non-orthogonal nature of GFDM, along with IAI. In this article, the authors propose a system that combines the Offset-Quadrature Amplitude Modulation (OQAM) with GFDM to mitigate self-induced interference, by using a simple Matched Filter (MF) detector and minimum additional processing at the receiver. Simulation results show a considerable achieved improvement in BER by the proposed OQAM/GFDM compared to QAM/GFDM when using MMSE-based Ordered Successive Interference Cancellation (OSIC) detector. Furthermore, this system is unaffected by the roll-off factor variations of used pulse-shaping filters.

scholarly journals Channel Estimation in MIMO-OFDM System

2014 ◽  
Vol 14 (2) ◽  
pp. 97-102
Author(s):  
SR Aryal ◽  
H Dhungana
Keyword(s):  
Channel Estimation ◽  
Mean Square Error ◽  
Minimum Mean Square Error ◽  
Multipath Fading ◽  
Spatial Multiplexing ◽  
Diversity Gain ◽  
Estimation Methods ◽  
Mean Square ◽  
Ofdm System ◽  
Mimo Ofdm

There are no limit of human desire, so day by day we need much higher data speed to facilitate our need but every physical resource like frequency band, transmit signal strength are finite. Within the given limited resource, higher data speed is accomplished by new proficiency called Multiple Input Multiple Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM) system. MIMO-OFDM fulfills the high data rate requirement through spatial multiplexing gain and improved link reliability due to antenna diversity gain. With this technique, both interference reduction and maximum diversity gain are achieved by increasing number of antennae on either side. Received signal in MIMO-OFDM system is usually distorted by multipath fading. In order to recover the transmitted signal correctly, channel effect must be estimated and repaired at receiver. In this paper the performance evaluating parameter mean square error and symbol error rate of least square error, minimum mean square error and DFT based channel estimation methods are estimated and appropriate solution is recommended. Furthermore, comparison among their characteristics is simulated in MATLAB and useful conclusion is delineated. DOI: http://dx.doi.org/10.3126/njst.v14i2.10421   Nepal Journal of Science and Technology Vol. 14, No. 2 (2013) 97-102

scholarly journals Improved Training Sequence Channel Estimation Scheme in 16QAM MB-OFDM UWBoF System

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Changqing Xiang ◽  
Xi Yang ◽  
Xuan Zhou ◽  
Xiaojun Zhu ◽  
Jincan Xu ◽  
...  
Keyword(s):  
Channel Estimation ◽  
Time Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
Single Mode ◽  
Training Sequence ◽  
Single Mode Fiber ◽  
Frequency Division ◽  
Training Sequences ◽  
Estimation Scheme ◽  
Simulation Results

In this paper, an improved channel estimation scheme based on time-domain orthogonal gray complementary training sequence (Golay TS) is proposed to resist subcarrier mutual beat interference in 16-quadrature amplitude modulation multiband orthogonal-frequency-division-multiplexing ultrawide band over fiber (16QAM MB-OFDM UWBoF) systems. The simulation results showed that the performance of system with the improved Golay TS channel estimation scheme was improved by about 1 dB compared with the traditional Golay TS channel estimation scheme, at a bit error rate (BER) of 3.8 × 10−3 after 70 km standard single mode fiber (SSMF) transmission. At the same time, the synchronization and channel estimation performance of Golay TS and the selected frequency-domain orthogonal training sequences (TSs) were compared. The simulation results showed that the performance of system with the TSs channel estimation was improved by about 2.7 dB compared with the improved Golay TS channel estimation.

scholarly journals Channel Estimation for OFDM-Based Amplify-and-Forward Cooperative System Using Relay-Superimposed Pilots

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Xianwen He ◽  
Gaoqi Dou ◽  
Jun Gao
Keyword(s):  
Lower Bound ◽  
Channel Estimation ◽  
Data Stream ◽  
Direct Link ◽  
Frequency Division ◽  
Cooperative System ◽  
Amplify And Forward ◽  
System A ◽  
Pilot Symbols ◽  
Simulation Results

For the OFDM-based Amplify-and-Forward cooperative system, a novel relay-superimposed pilot strategy is proposed, where the source pilot symbols are frequency division multiplexed to estimate the cascaded channel while relay pilot sequence is superimposed onto the top of the cooperative data stream for second-hop channel estimation. This method avoids the loss of data rate for additional pilot subcarriers but results in the interference of unknown cooperative data. To remove the interference of cooperative data during the estimation of second-hop channel, the Cooperative Interference Cancelation scheme assisted by cooperative data from direct link is proposed. We derive the approximated lower bound for the MSE of second-hop channel estimation. Simulation results are presented to validate the performance of the proposed schemes.

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.

The Study of Interpolation Algorithms in OFDM Systems

2013 ◽  
Vol 321-324 ◽  
pp. 2837-2840
Author(s):  
Xi Jun Zhang ◽  
Jian Bin Xue ◽  
Ying Lin ◽  
Ji Ai He
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Simulation Process ◽  
Interpolation Algorithms ◽  
Simulation Results

Orthogonal frequency division multiplexing (OFDM) is a kind of highly transmission technology. It has been taken more and more attention in many ways. In this paper it mainly discussed the simulation process and several interpolation algorithms in OFDM system. Using computer we simulate the interpolation algorithms in OFDM channel estimation. Through the simulation results we compare the advantage and disadvantage of the interpolation algorithms. At last we can use the conclusion to choose the correct interpolation algorithms in OFDM channel estimation.

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