scholarly journals Noise Cancellation for HIPERLAN/2 with Open Loop Transmit Diversity Technique

Inventions ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 46
Author(s):  
Maan A. Yahya ◽  
Omar Ibrahim Alsaif ◽  
Ibrahim Ahmed Saleh ◽  
Ahmed M. Abdulkhaleq ◽  
Naser Ojaroudi Parchin ◽  
...  
Keyword(s):  
System Performance ◽  
Signal To Noise Ratio ◽  
Open Loop ◽  
Feedback Signal ◽  
Transmitted Power ◽  
Signal Process ◽  
Suggested Approach ◽  
Received Power ◽  
Time Diversity ◽  
Diversity Technique

A new proposed method is presented, where multiple antennas have been applied into HIPERLAN/2 system in addition to employing space-time diversity technique, especially the Alamouti technique. The suggested approach is used to cancel or reduce the effect of the transmitted power using a feedback signal process within the transceiver unit, especially when the antennas are closely located and working in full-mode duplexing. Several parameters including the transmitted power, the received power, and the feedback accuracy have been considered for testing the performance of the system in term of the signal to noise ratio (SNR) versus bit error rate (BER). A software programme using MATLAB and Simulink is implemented to evaluate the proposed method. The results showed that the system performance is heavily dependent on the amount of the mismatch in the feedback, the received power, and the transmitted power. The performance of the system decreases as the feedback accuracy increases when the transmitted power and the received power are constant. At the same time, the performance of the system decreases as the transmitted power increases when the received power and the mismatch are constant. Finally, the increase in the received power enhances the system performance when the other parameters are constant.

Performance Evaluation of Space-Time and Harq Diversity in MIMO HSDPA

2012 ◽  
Vol 4 (3) ◽  
pp. 71-86
Author(s):  
Walid Hakimi ◽  
Ammar Mahmoud
Keyword(s):  
System Performance ◽  
Signal To Noise Ratio ◽  
Space Time ◽  
System Capacity ◽  
Time Diversity ◽  
Data Rates ◽  
Alamouti Coding ◽  
User Data ◽  
Alamouti Code ◽  
Interference Canceller

Multi-antenna techniques can be used to achieve improved system performance, including improved system capacity (more users per cell) and improved coverage (possibility for larger cells), as well as improved service provisioning, for example, higher per-user data rates. This study provides an overview of space-time diversity technique using Alamouti codes applied to the 3G evolution. The delays introduced by HARQ retransmission decrease the performance of the HSDPA system. Multi-antenna techniques are specifically applied to HSDPA to avoid HARQ retransmissions. The authors demonstrate that space-time Rake detector in MIMO 2x2 based on Alamouti code without HARQ process could give better performances than MIMO 2x1 taking into account the HARQ context. In the case of MIMO 2x2,they also observed that the limit of retransmissions affects the system performance and efficiency. Using the generalized Alamouti coding technique in MIMO 4x4 with Multipath Parallel Interference Canceller (MPIC) detector, we achieve notable improvement of performance under the same channel and signal to-Noise Ratio (SNR) conditions.

Robustness Speaker Recognition Based on Feature Space in Clean and Noisy Condition

2019 ◽  
Vol 9 (4) ◽  
pp. 497-506 ◽  
Author(s):  
Khamis A. Al-Karawi
Keyword(s):  
Speech Processing ◽  
Speaker Recognition ◽  
System Performance ◽  
Speaker Verification ◽  
Signal To Noise Ratio ◽  
Recognition Performance ◽  
Feature Space ◽  
Signal To Noise ◽  
Verification Systems ◽  
Noisy Condition

Background & Objective: Speaker Recognition (SR) techniques have been developed into a relatively mature status over the past few decades through development work. Existing methods typically use robust features extracted from clean speech signals, and therefore in idealized conditions can achieve very high recognition accuracy. For critical applications, such as security and forensics, robustness and reliability of the system are crucial. Methods: The background noise and reverberation as often occur in many real-world applications are known to compromise recognition performance. To improve the performance of speaker verification systems, an effective and robust technique is proposed to extract features for speech processing, capable of operating in the clean and noisy condition. Mel Frequency Cepstrum Coefficients (MFCCs) and Gammatone Frequency Cepstral Coefficients (GFCC) are the mature techniques and the most common features, which are used for speaker recognition. MFCCs are calculated from the log energies in frequency bands distributed over a mel scale. While GFCC has been acquired from a bank of Gammatone filters, which was originally suggested to model human cochlear filtering. This paper investigates the performance of GFCC and the conventional MFCC feature in clean and noisy conditions. The effects of the Signal-to-Noise Ratio (SNR) and language mismatch on the system performance have been taken into account in this work. Conclusion: Experimental results have shown significant improvement in system performance in terms of reduced equal error rate and detection error trade-off. Performance in terms of recognition rates under various types of noise, various Signal-to-Noise Ratios (SNRs) was quantified via simulation. Results of the study are also presented and discussed.

40 Gb/s High-speed mode-division multiplexing transmission employing NRZ modulation format

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Rabiu Imam Sabitu ◽  
Nafizah Goriman Khan ◽  
Amin Malekmohammadi
Keyword(s):  
System Performance ◽  
High Speed ◽  
Direct Detection ◽  
Signal To Noise Ratio ◽  
Optical Signal ◽  
Threshold Power ◽  
Modulation Format ◽  
Transmission Distance ◽  
Mode Division Multiplexing ◽  
Speed Mode

AbstractThis report examines the performance of a high-speed MDM transmission system supporting four nondegenerate spatial modes at 10 Gb/s. The analysis adopts the NRZ modulation format to evaluate the system performance in terms of a minimum power required (PN) and the nonlinear threshold power (PTH) at a BER of 10−9. The receiver sensitivity, optical signal-to-noise ratio, and the maximum transmission distance were investigated using the direct detection by employing a multimode erbium-doped amplifier (MM-EDFA). It was found that by properly optimizing the MM-EDFA, the system performance can significantly be improved.

scholarly journals Modified LQG/LTR Control Methodology in Active Structural Control

2003 ◽  
Vol 22 (2) ◽  
pp. 97-108 ◽  
Author(s):  
Yan Sheng ◽  
Chao Wang ◽  
Ying Pan ◽  
Xinhua Zhang
Keyword(s):  
Structural Control ◽  
Signal To Noise Ratio ◽  
Open Loop ◽  
Control Force ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian ◽  
Control Approach ◽  
Active Structural Control ◽  
Loop Transfer Recovery ◽  
Control Methodology

This paper presents a new active structural control design methodology comparing the conventional linear-quadratic-Gaussian synthesis with a loop-transfer-recovery (LQG/LTR) control approach for structures subjected to ground excitations. It results in an open-loop stable controller. Also the closed-loop stability can be guaranteed. More importantly, the value of the controller's gain required for a given degree of LTR is orders of magnitude less than what is required in the conventional LQG/LTR approach. Additionally, for the same value of gain, the proposed controller achieves a much better degree of recovery than the LQG/LTR-based controller. Once this controller is obtained, the problems of control force saturation are either eliminated or at least dampened, and the controller band-width is reduced and consequently the control signal to noise ratio at the input point of the dynamic system is increased. Finally, numerical examples illustrate the above advantages.

scholarly journals A novel demodulation algorithm for VHF Data Broadcast signals in multi-sources augmentation navigation system

2020 ◽  
Vol 16 (3) ◽  
pp. 155014772091477
Author(s):  
Hongwei Zhao ◽  
Zichun Zhang ◽  
Xiaozhu Shi ◽  
Yihui Yin
Keyword(s):  
Navigation System ◽  
Signal To Noise Ratio ◽  
Open Loop ◽  
Timing Recovery ◽  
Loop Structure ◽  
Frame Synchronization ◽  
Source Information ◽  
Carrier Synchronization ◽  
Data Broadcast ◽  
Training Symbol

The augmentation navigation system based on multi-source information fusion can significantly improve position accuracy, and the multi-source information is usually transmitted through VHF Data Broadcast . Aiming at the burst characteristics of VHF Data Broadcast, this article proposed a novel demodulation algorithm based on open-loop structure. When a VHF Data Broadcast burst is detected, the timing recovery should be finished first, and the value of cross-correlation between the timing-recovered signal and the local training symbol is calculated to complete the frame synchronization. Then, the data-aided and non-data-aided algorithms are used to estimate the frequency offset. Finally, the phase offset is estimated and the carrier synchronization is accomplished. The simulation results demonstrate that the proposed algorithm can quickly accomplished carrier synchronization without using feedback-loop structure, and the bit error rate is less than 10−4 when the signal-to-noise ratio is greater than 17 dB, which satisfy the requirement of receiving VHF Data Broadcast signals in augmentation navigation system. Therefore, the proposed algorithm can be used for receiving VHF Data Broadcast signals.

scholarly journals Analysis of Time Diversity Gain for Satellite Communication Link based on Ku-Band Rain Attenuation Data Measured in Malaysia

2018 ◽  
Vol 8 (4) ◽  
pp. 2608
Author(s):  
Islam Md. Rafiqul ◽  
Ali Kadhim Lwas ◽  
Mohamed Hadi Habaebi ◽  
Md Moktarul Alam ◽  
Jalel Chebil ◽  
...  
Keyword(s):  
Satellite Communication ◽  
Satellite Communications ◽  
Earth Satellite ◽  
Rain Attenuation ◽  
Diversity Gain ◽  
Communication Link ◽  
Time Diversity ◽  
Communication Links ◽  
System Time ◽  
Diversity Technique

<p><span>This paper reports a study on mitigation of propagation impairments on Earth–space communication links. The study uses time diversity as a technique for mitigating rain propagation impairment in order to rectify rain fade. Rain attenuation time series along earth-to-satellite link were measured for two years period at 12.255 GHz in Malaysia. The time diversity technique was applied on measured rain fade to investigate the level of possible improvement in system. Time diversity gain from measured one-minute rain attenuation for two years period was estimated and significant improvement was observed with different delays of time. These findings will be utilized as a useful tool for link designers to apply time diversity as a rain fade mitigation technique in Earth-satellite communications systems.</span></p>

Basic Functions of Fiber Bragg Grating Effects on the Optical Fiber Systems Performance Efficiency

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
IS Amiri ◽  
Ahmed Nabih Zaki Rashed ◽  
P Yupapin
Keyword(s):  
Optical Fiber ◽  
Fiber Bragg Grating ◽  
System Performance ◽  
Signal To Noise Ratio ◽  
Optical Power ◽  
Bragg Grating ◽  
Signal To Noise ◽  
Linear Chirp ◽  
Basic Functions ◽  
High Bit Rates

AbstractThe study presents the basic apodization and chirp functions based fiber Bragg grating (FBG) for upgrading optical fiber performance efficiency. Variations of apodization and chirp functions are studied with grating length variations. Optical power after FBG, signal to noise ratio, maximum Q-factor, and output power are measured in the presence of the chirp functions. Gaussian apodization function has outlined good performance than other proposed apodization functions. As well as linear chirp function is better performance than other chirp functions. The optical system performance tested with/without chirp effects with high bit rates.

RFID Loop Tags for Merchandise Identification Onboard Ships

2014 ◽  
Vol 1036 ◽  
pp. 969-974
Author(s):  
Daniela Deacu
Keyword(s):  
Radio Frequency Identification ◽  
Block Diagram ◽  
Simulated Data ◽  
Open Loop ◽  
Closed Loops ◽  
Passive Tags ◽  
Received Power ◽  
Resonance Frequencies ◽  
Frequency Identification ◽  
Good Agreement

Radio frequency identification (RFID) is one of the most actual techniques employed to control the circuit of merchandises, as an alternative to the classical barecode. RFID tags should be cheap and easy to reproduct on a multitude of dielectric supports. There are several types of RFID systems, depending on whether tag and/or reader are active or passive. For cost reasons, merchandise identification should use active reader and passive tag, as the latter might be manufactured on a cheap FR4 support or printed directly on paper, by using a conductive ink. Passive tags can be shaped as straight dipoles, meandered dipoles, or loops. When a small area is required, loops are more appropriated. Codes are made different one from another by using on the same tag antennas with different resonance frequencies. Another advantage of loops is that they can be placed one inside other, so the occupied area is even smaller compared to other multi-resonant tags. Firstly, a single loop is analyzed, in order to model the resonant behaviour, correlated to the loop geometry and size. Open and closed loops are studied; the lowest resonance frequency for a given loop length is achieved for the open loop. In that case, the loop is resonating as a dipole. Next, a tag with three concentric loops is investigated. Separately, a small loop is used on the tag, in order to couple the received power in a resistor. When the tag is close to the reader, the latter is triggered if power is absorbed simultaneously on the three expected frequencies. The proposed tag was simulated and manufactured. Results show a good agreement between measured and simulated data. Finally, a block diagram for the reader was proposed.

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