scholarly journals Design of Robust Pulses to Insufficient Synchronization for OFDM/OQAM Systems in Doubly Dispersive Channels

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Yu Zhao ◽  
Xihong Chen ◽  
Lunsheng Xue ◽  
Qun Zhang
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Optimization Problem ◽  
Carrier Frequency Offset ◽  
Hermite Functions ◽  
Quadratic Program ◽  
Frequency Division ◽  
Timing Offset ◽  
Dispersive Channels ◽  
Quadratically Constrained

This paper presents a pulse shaping method robust to insufficient synchronization in orthogonal frequency division multiplexing with offset quadrature amplitude modulation (OFDM/OQAM) systems over doubly dispersive (DD) channels. The proposed pulse is designed as a linear combination of several well localized Hermite functions. The coefficients optimization problem is modeled as a nonconvex constrained fractional programming problem based on the signal-to-interference ratio (SIR) maximization criterion. An efficient iterative algorithm is applied to simplify the problem to a series of quadratically constrained quadratic program (QCQP) problems which can be solved by semidefinite relaxation (SDR) method. Simulation results show that the proposed pulse is superior to traditional pulses with respect to SIR performance over DD channels in the presence of carrier frequency offset (CFO) and timing offset (TO).

scholarly journals Characterization of GFDM Signal with Timing Offset, CFO, Non-Linearity, and PN

2021 ◽  
Author(s):  
Fereshteh Yazdani ◽  
Abbas Mohammadi ◽  
Abdolali Abdipour ◽  
Mohammad Kazemi
Keyword(s):  
Power Amplifier ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Matched Filter ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Synchronization Errors ◽  
Timing Offset ◽  
Nonlinear Power Amplifier

Abstract In this paper, we study the joint effects of timing offset (TO), carrier frequency offset (CFO), nonlinear power amplifier distortion, and phase noise (PN) on generalized frequency division multiplexing (GFDM) system. Closed form expressions for signal-to-interference ratio (SIR) at GFDM receiver with synchronization errors and PN using a nonlinear power amplifier is derived. Then, we have been conducted simulation studies to compare the performance of GFDM systems with orthogonal frequency division multiplexing (OFDM) systems using matched filter (MF) and zero forcing (ZF), in presence of these impairments. The results show that GFDM systems are more robust against TO and PN while they are more sensitive to CFO and nonlinear distortion compared to OFDM systems.

scholarly journals The Analysis of the Effect and Reduction of Carrier Frequency Offset in Orthogonal Frequency Division Multiplexing (OFDM) Multiple Input Multiple Output (MIMO)

2020 ◽  
Vol 19 (2) ◽  
pp. 219
Author(s):  
Willy Sucipto ◽  
I Nyoman Pramaita ◽  
NMAE Dewi Wirastuti
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Carrier Frequency Offset ◽  
Multiple Input Multiple Output ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
A Value ◽  
Multiple Input ◽  
Input Multiple Output

Abstract— The development of cellular telecommunication provides users to experience fast and stable transmission. This standard of transmission is proportional to the needs of the devices and systems used. We are currently in the fourth generation (4G) of cellular technology. The key technologies used in 4G are Orthogonal Frequency Division Multiplexing (OFDM) which uses the concept of orthogonality for bandwidth efficiency and Multiple Input Multiple Output (MIMO) which uses the concept of diversity to improve performance. But in implementation this system will have problems with the transmission channel. The problem that occurs is signal attenuation due to Carrier Frequency Offset (CFO). This CFO will cause the orthogonal character built from the OFDM system to experience a decline in performance. The decline in performance is due to the occurrence of Intercarrier Interference (ICI). To overcome this problem, the method used in this simulation are Improved Sinc Power Pulse (ISP) and Rectangular Pulse (REC). The results showed that ISP had a relatively better BER value than REC and without using the pulse shaping method. The minimum BER value obtained from the simulation is ISP with a value of 0.0001 while REC produces a value of 0.0006 and without pulse shaping produces a BER value of 0.0038.

scholarly journals Robust Preamble-Based Timing Synchronization for OFDM Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yun Liu ◽  
Fei Ji ◽  
Hua Yu ◽  
Dehuan Wan ◽  
Fangjiong Chen ◽  
...  
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Estimation Method ◽  
Multipath Fading ◽  
New Method ◽  
Timing Synchronization ◽  
Ofdm Systems ◽  
Multipath Fading Channels ◽  
Timing Offset

This study presents a novel preamble-based timing offset estimation method for orthogonal frequency division multiplexing (OFDM) systems. The proposed method is robust, immune to the carrier frequency offset (CFO), and independent of the structure of the preamble. The performance of the new method is demonstrated in terms of mean square error (MSE) obtained by simulation in multipath fading channels. The results indicate that the new method significantly improves timing performance in comparison with existing methods.

scholarly journals ECCM Schemes against Deception Jamming Using OFDM Radar with Low Global PAPR

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2071
Author(s):  
Xinhai Wang ◽  
Gong Zhang ◽  
Xiangmin Wang ◽  
Qingqing Song ◽  
Fangqing Wen
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Optimization Problem ◽  
Average Power ◽  
Doppler Spectrum ◽  
Frequency Division ◽  
Ofdm Symbol ◽  
Alternating Direction ◽  
Parseval’S Theorem ◽  
Joint Range ◽  
Huge Challenge

In this paper, a type of effective electronic counter-countermeasures (ECCM) technique for suppressing the high-power deception jamming using an orthogonal frequency division multiplexing (OFDM) radar is proposed. Concerning the velocity deception jamming, the initial phases of the pulses transmitted in a coherent processing interval (CPI) are designed to minimize the jamming power within a specific range, forming a notch around the jamming in the Doppler spectrum. For the purpose of suppressing the range deception jamming and the joint range-velocity deception jamming, the phase codes of the subcarriers belonging to the OFDM pulses are optimized to minimize the jamming power, distributing some specific bands in the range and the range-velocity domain, respectively. According to Parseval’s theorem, the phase encoding, acting as the coding manner of the OFDM subcarriers can ensure that the energy of each OFDM symbol stays the same. It is worth noticing that the phase codes of the OFDM subcarriers can influence the peak-to-average power ratio (PAPR). Thus, an optimization problem is formulated to optimize the phase codes of the subcarriers under the constraint of global PAPR, which can regulate the PAPRs of multiple OFDM symbols at the same time. The proposed problem is non-convex; therefore, it is a huge challenge to tackle. Then we present a method named by the phase-only alternating direction method multipliers (POADMM) to solve the aforementioned optimization problem. Some necessary simulation results are provided to demonstrate the effectiveness of the proposed radar signaling strategy

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