scholarly journals A Multistandard Frequency Offset Synchronization Scheme for 802.11n, 802.16d, LTE, and DVB-T/H Systems

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Javier González-Bayón ◽  
Carlos Carreras ◽  
Ove Edfors
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Ofdm Systems ◽  
Resource Requirements ◽  
And Performance ◽  
Synchronization Structure ◽  
Performance Results ◽  
Wireless Standards ◽  
Common Architecture

Carrier frequency offset (CFO) synchronization is a crucial issue in the implementation of orthogonal frequency division multiplexing (OFDM) systems. Since current technology tends to implement different standards in the same wireless device, a common frequency synchronization structure is desirable. Knowledge of the physical frame and performance and cost system requirements are needed to choose the most suitable scheme. This paper analyzes the performance and FPGA resource requirements of several data-aided (DA) and decision-directed (DD) schemes for four wireless standards: 802.11n, 802.16d, LTE, and DVB-T/H. Performance results of the different methods are shown as BER plots and their resource requirements are evaluated in terms of the number of computations and operators that are needed for each scheme. As a result, a common architecture for the four standards is proposed. It improves the overall performance of the best of the schemes when the four standards are considered while reducing the required resources by 50%.

Time and Frequency Synchronization for MIMO-OFDM Systems

2013 ◽  
Vol 321-324 ◽  
pp. 2888-2891
Author(s):  
Jing Peng Gao ◽  
Chao Qun Wu ◽  
Dan Feng Zhao
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Time Synchronization ◽  
Multiple Input Multiple Output ◽  
Frequency Offset ◽  
Time Instant ◽  
Frequency Synchronization ◽  
Ofdm Systems ◽  
Frequency Offset Estimation ◽  
Mimo Ofdm

Any carrier frequency offset will cause a loss of subcarrier orthogonality which results in ICI and hence performance degrades severely in MIMO-OFDM systems. In this paper, a time and frequency synchronization solution for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems is proposed. The synchronization is achieved using one Constant Amplitude Zero Auto Correlation (CAZAC) sequence-based preamble which is simultaneously transmitted from all transmit antennas in the same OFDM time instant. The synchronization is accomplished sequentially by coarse time synchronization, fractional frequency offset estimation, integral frequency offset estimation and fine time synchronization. The simulation shows that the proposed algorithm can estimate the timing and frequency offsets efficiently in MIMO-OFDM systems, especially in low signal-to-noise ratio condition.

scholarly journals INTER CARRIER INTERFERENCE AND SIGNAL TO INTERFERENCE RATIO OF VARIOUS PULSE SHAPING FUNCTIONS USED IN OFDM SYSTEM WITH CARRIER FREQUENCY OFFSET

2012 ◽  
pp. 68-71
Author(s):  
SHANKAR AENAGANDULA ◽  
ASHOK KUMAR ◽  
SRINIVAS K ◽  
MONIKA NANDA
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Carrier Frequency Offset ◽  
Signal To Noise Ratio ◽  
Frequency Offset ◽  
Performance Comparison ◽  
Intercarrier Interference ◽  
Ofdm Systems ◽  
Ofdm System

Orthogonal Frequency Division Multiplexing (OFDM) is the important modulation of choice for fourthgeneration broadband multimedia wireless systems. This paper is focused on the problem of reducing the intercarrierinterference (ICI) and signal to noise ratio in the transmission over OFDM using various pulse shaping methods. Here we have performed a detailed performance comparison of various pulse shaping functions used in OFDM System with Carrier Frequency Offset. They appear to be suitable for transmission in OFDM systems with carrier frequency offset. The results obtained by analysis show that the performance improvement over conventional pulse shapes, are significant for reducing average intercarrier-interference (ICI) power and increased ratio of average signal power to average ICI power (SIR).

scholarly journals Comparison of SPS and FA methods for Blind Carrier Frequency Offset Estimation in OFDM systems

2022 ◽  
Vol 16 ◽  
pp. 7-11
Author(s):  
K. Seshadri Sastry ◽  
K. Baburao ◽  
A.V. Prabu ◽  
G.Naveen Kumar
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Frequency Offset Estimation ◽  
Synchronization Errors ◽  
Carrier Frequency Offset Estimation

In orthogonal frequency-division multiplexing (OFDM) systems, synchronization issues are of great importance since synchronization errors might destroy the orthogonality among all subcarriers and, therefore, introduce intercarrier interference (ICI) and intersymbol interference (ISI). Several schemes of frequency offset estimation in OFDM systems have been investigated. This paper compares performance and computational complexity of Smoothing Power Spectrum (SPS) and Frequency Analysis (FA) methods for blind carrier frequency offset (CFO) estimation in OFDM systems.

Frequency Synchronization for OFDM/OFDMA Systems

2012 ◽  
pp. 216-236
Author(s):  
Javier González Bayón ◽  
Carlos Carreras Vaquer ◽  
Angel Fernández Herrero
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Base Station ◽  
Frequency Synchronization ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Single Carrier ◽  
Two Stages ◽  
Estimation And Correction

Orthogonal frequency division multiplexing (OFDM) has been the focus of many studies in wireless communications because of its high transmission capability and its robustness to the effects of frequency-selective multipath channels. However, it is well known that OFDM systems are much more sensitive to a carrier frequency offset (CFO) than single carrier schemes with the same bit rate. Therefore, a frequency synchronization process is necessary to overcome this sensitivity to frequency offset. Synchronization is performed in two stages: acquisition and tracking. After a first estimation and correction of the CFO performed in the acquisition stage, there still remains a residual frequency offset (RFO) due to real system conditions. Therefore, the RFO tracking has to be performed for all the receiving data. Frequency synchronization is even more complicated for uplink communications in OFDMA (orthogonal frequency division multiple access) systems because the base station (BS) has to deal with signals from different users in the same bandwidth. Each user’s data is affected by a different CFO. Because of this, estimation and correction of the CFOs cannot be accomplished by the same methods as in OFDM systems.

Compressed Sensing Based Blind Carrier Frequency Offset Estimation for OFDM System

2013 ◽  
Vol 756-759 ◽  
pp. 1894-1897 ◽  
Author(s):  
Gang Yang ◽  
Hua Xin Yu ◽  
Xiao Fei Zhang
Keyword(s):  
Compressed Sensing ◽  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Signal To Noise Ratio ◽  
Estimation Algorithm ◽  
Frequency Offset ◽  
Ofdm Systems ◽  
Carrier Frequency Offset Estimation ◽  
Sensing Model

In this paper, we address the problem of carrier frequency offset (CFO) estimation for Orthogonal Frequency Division Multiplexing (OFDM) systems. This paper links CFO estimation problem in OFDM systems to the compressed sensing model. Exploiting this link, it derives a compressed sensing-based CFO estimation algorithm. The proposed algorithm has better CFO estimation performance than ESPRIT method with lower signal-to-noise ratio (SNR). Simulation results illustrate performance of this algorithm.

scholarly journals An Algorithm Combining Synchronization and Channel Estimation for OFDM Systems

2009 ◽  
Author(s):  
Pham Hong Lien ◽  
Nguyen Duy Lai
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Multipath Fading ◽  
Frequency Offset ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Clock Frequency ◽  
Close Relationship ◽  
Ofdm Signals

OFDM (Orthogonal Frequency Division Multiplexing) is more and more popular in applications of digital communications because of the effective spectrum and less impacts  of multipath fading. However, beside these advantages, OFDM signals are destroyed easily by errors such as CFO (Carrier Frequency Offset), SFO (Sampling Clock Frequency Offset). Thus, it’s necessaryto have robustly offset algorithms to overcome these disadvantages. Studies about OFDM we just examined channel estimation with assumptions that synchronization is perfect, and vice versa. However, they have a close relationship, channel estimation can be restricted if synchronization is bad, and vice versa. This paper presents an algorithm combining synchronization and channel estimation in OFDM systems. The algorithm is compared with other proposed algorithms by simulation. The simulation result of the algorithm combining synchronization and channel estimation is close to that of ideal conditions: perfect channel estimation and synchronization.

Estimation of OFDM Carrier Frequency Offset Robust to Offset Variation

2013 ◽  
Vol 284-287 ◽  
pp. 2642-2646
Author(s):  
Chang Ha Yu ◽  
Young Po Lee ◽  
Sun Yong Kim ◽  
Gyu In Jee ◽  
Seok Ho Yoon
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Estimation Scheme ◽  
Conventional Scheme ◽  
Estimation Range

In this paper, we propose a novel carrier frequency offset (CFO) estimation scheme for orthogonal frequency division multiplexing (OFDM) systems. The proposed scheme has much wider estimation range compared with that of the conventional scheme, making it more robust to the fractional FO variation. Numerical results demonstrate that the proposed scheme has better estimation performance than the conventional scheme for wider fractional FO range.

An Eigenvalue Based Carrier Frequency Offset Estimator for OFDM Systems

2013 ◽  
Vol 2 (5) ◽  
pp. 475-478 ◽  
Author(s):  
Abdel Aziz M. Al-Bassiouni ◽  
Muhammad Ismail ◽  
Weihua Zhuang
Keyword(s):  
Carrier Frequency ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Ofdm Systems
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