scholarly journals Wi-Fi Backscatter System with Tag Sensors Using Multi-Antennas for Increased Data Rate and Reliability

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1314
Author(s):  
Taeoh Kim ◽  
Hyobeen Park ◽  
Yunho Jung ◽  
Seongjoo Lee
Keyword(s):  
Computational Complexity ◽  
Euclidean Distance ◽  
Multiple Antennas ◽  
Power Level ◽  
Low Complexity ◽  
Data Rate ◽  
Threshold Method ◽  
Channel State ◽  
Distance Method ◽  
Ber Performance

In this paper, we propose tag sensor using multi-antennas in a Wi-Fi backscatter system, which results in an improved data rate or reliability of the signal transmitted from a tag sensor to a reader. The existing power level modulation method, which is proposed to improve data rate in a Wi-Fi backscatter system, has low reliability due to the reduced distance between symbols. To address this problem, we propose a Wi-Fi backscatter system that obtains channel diversity by applying multiple antennas. Two backscatter methods are described for improving the data rate or reliability in the proposed system. In addition, we propose three low complexity demodulation methods to address the high computational complexity problem caused by multiple antennas: (1) SET (subcarrier energy-based threshold) method, (2) TCST (tag’s channel state-based threshold) method, and (3) SED (similar Euclidean distance) method. In order to verify the performance of the proposed backscatter method and low complexity demodulation schemes, the 802.11 TGn (task group n) channel model was utilized in simulation. In this paper, the proposed tag sensor structure was compared with existing methods using only sub-channels with a large difference in received CSI (channel state information) values or adopting power-level modulation. The proposed scheme showed about 10 dB better bit error rate (BER) performance and throughput. Also, proposed low complexity demodulation schemes were similar in BER performance with a difference of up to 1 dB and the computational complexity was reduced by up to 60% compared to the existing Euclidean distance method.

scholarly journals Low-Complexity Detection Algorithms for Spatial Modulation MIMO Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Xinhe Zhang ◽  
Yuehua Zhang ◽  
Chang Liu ◽  
Hanzhong Jia
Keyword(s):  
Computational Complexity ◽  
Mimo Systems ◽  
Optimal Solution ◽  
Low Complexity ◽  
Search Tree ◽  
Spatial Modulation ◽  
Algorithm Analysis ◽  
Detection Algorithms ◽  
Search Order ◽  
Ber Performance

In this paper, the authors propose three low-complexity detection schemes for spatial modulation (SM) systems based on the modified beam search (MBS) detection. The MBS detector, which splits the search tree into some subtrees, can reduce the computational complexity by decreasing the nodes retained in each layer. However, the MBS detector does not take into account the effect of subtree search order on computational complexity, and it does not consider the effect of layers search order on the bit-error-rate (BER) performance. The ost-MBS detector starts the search from the subtree where the optimal solution is most likely to be located, which can reduce total searches of nodes in the subsequent subtrees. Thus, it can decrease the computational complexity. When the number of the retained nodes is fixed, which nodes are retained is very important. That is, the different search orders of layers have a direct influence on BER. Based on this, we propose the oy-MBS detector. The ost-oy-MBS detector combines the detection order of ost-MBS and oy-MBS together. The algorithm analysis and experimental results show that the proposed detectors outstrip MBS with respect to the BER performance and the computational complexity.

scholarly journals PAPR Reduction in MIMO-OFDM Systems Using Low- Complexity Additive Signal Mixing

2021 ◽  
pp. 468-478
Author(s):  
Stephen Kiambi ◽  
◽  
Elijah Mwangi ◽  
George Kamucha
Keyword(s):  
Communication Systems ◽  
Window Size ◽  
Low Complexity ◽  
Data Rate ◽  
Papr Reduction ◽  
Ofdm Systems ◽  
High Data ◽  
Communication Technique ◽  
Mimo Ofdm ◽  
Ber Performance

A MIMO-OFDM wireless communication technique possesses several advantages accrued from combining MIMO and OFDM techniques such as increased channel capacity and improved BER performance. This has made the technique very amiable to current and future generations of communication systems for high data-rate transmission. However, the technique also inherits the high PAPR problem associated with OFDM signals—a problem still requiring a practical solution. This work proposes a PAPR reduction algorithm for solving the problem of high PAPR in MIMO-OFDM systems. The proposed method uses a low-complexity signal mixing concept to combine the original transmit signal and a generated peak-cancelling signal. The computational complexity of the proposed method is O(M) , which is very much less than O(N log2 N) of the FFT algorithms. This is because M, which denotes the number of nonzero peakcancelling samples, is much less than N, the FFT window size. The proposed method was found to achieve high PAPR reductions while utilizing only a few nonzero peak-cancelling samples and it does not significantly change the power of the transmitted signal. For example, with M=5% of 256-point IFFT samples, corresponding to a data rate loss of 4.8%, a large PAPR reduction of 5.9 dB could be achieved at a small power loss of 0.09 dB. Compared with other methods proposed in literature, the proposed method was found to outperform them in terms of PAPR reductions and BER performance.

scholarly journals Quantization Error Correction Schemes for Lattice-Reduction Aided MIMO Detectors

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Tien Duc Nguyen ◽  
Tadashi Fujino ◽  
Xuan Nam Tran
Keyword(s):  
Error Correction ◽  
Euclidean Distance ◽  
Low Complexity ◽  
Optimal Performance ◽  
Lattice Reduction ◽  
Quantization Scheme ◽  
Quantization Step ◽  
Performance Improvements ◽  
Simulation Results ◽  
Ber Performance

Lattice reduction aided (LRA) linear detectors have been known to achieve near optimal performance at low complexity. However, one weakness of LRA detector is that the quantization step in LRA detector is not optimal. Based on simulation results, we show that most of detection errors in LRA linear detectors are due to quantization errors. We then propose two methods to correct the quantization errors. In the first method, sphere detectors are introduced to correct quantization errors at low additional complexity. As a second approach, we propose a list quantization scheme which can generate a list of candidate symbols from the original LRA estimated symbols. From these listed symbols, decisions are made according to the minimum Euclidean distance between the received and estimated points. It is shown by simulations that both methods provide significant BER performance improvements with only a small additional complexity.

Performance Analysis of Efficient and Low Complexity MIMO-OFDM System Using Modified V-BLAST

2020 ◽  
Vol 10 (3) ◽  
pp. 302-307
Author(s):  
Brijesh Kumar Yadav ◽  
Rabindra Kumar Singh
Keyword(s):  
Computational Complexity ◽  
Performance Analysis ◽  
Low Complexity ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Mimo Ofdm ◽  
Ber Performance

Background and Objective: To analyze the performance of MIMO-OFDM system, VBLAST detection suffers from computational complexity as well as high BER. Methods: To improve the BER performance and to reduce the computational complexity of receiver, we propose a modified VBLAST detection in MIMO-OFDM Systems. Results: Simulation using MATLAB shows the improvement in computational complexity and in BER. Conclusion: This modified VBLAST reduces the complexity of MIMO-OFDM System to 44.2% and improvement in BER as compared to conventional VBLAST based MIMO-OFDM System.

Impact of Pointing Error on the BER Performance of an OFDM Optical Wireless Communication Link over Turbulent Condition

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Bobby Barua ◽  
S. P. Majumder
Keyword(s):  
Noise Analysis ◽  
Data Rate ◽  
Channel Noise ◽  
Communication Link ◽  
Optical Wireless ◽  
Power Penalty ◽  
Major Power ◽  
Pointing Error ◽  
Turbulent Condition ◽  
Ber Performance

AbstractAn analytical approach is developed in this paper to evaluate the bit error rate (BER) performance of an optical wireless (OW) communication system with multiplexing of the RF orthogonal frequency division (OFDM) over turbulent condition taking into account the effect of pointing error. The received signal is detected through direct detection receiver followed by RF synchronous demodulation including the effect of OW channel and different form of noises such as receiver thermal noise, background channel noise and photo detector shot noise. Analysis is developed for an OFDM system over the OW channel, taking into account the effect of pointing error between the transmitter and the receiver in turbulent condition and the analysis reveals that the OFDM OW system is less affected by pointing error with deference to the major power penalty at BER performance. For instance, power penalty at BER 10−9 is found to be 3 dB for 256 OFDM subcarriers with 9 millidegree displacement angle at a data rate of 10 Gbps under turbulent condition. It is found that the system is more influenced by the atmospheric turbulence at a higher data rate.

FULL-RATE AND LOW-COMPLEXITY SPACE-TIME BLOCK CODING CONCATENATED WITH CHANNEL CODES

2007 ◽  
Vol 06 (01) ◽  
pp. 5-14 ◽  
Author(s):  
XIANGBIN YU ◽  
GUANGGUO BI
Keyword(s):  
Channel Coding ◽  
Turbo Code ◽  
Multiple Antennas ◽  
Low Complexity ◽  
Space Time ◽  
System Throughput ◽  
Time Block ◽  
Coding Schemes ◽  
Full Diversity ◽  
Full Rate

Space-time block (STB) coding has been an effective transmit diversity technique for combating fading recently. In this paper, a full-rate and low-complexity STB coding scheme with complex orthogonal design for multiple antennas is proposed, and turbo code is employed as channel coding to improve the proposed code scheme performance further. Compared with full-diversity multiple antennas STB coding schemes, the proposed scheme can implement full data rate, partial diversity and a smaller complexity, and has more spatial redundancy information. Moreover, using the proposed scheme can form efficient spatial interleaving, thus performance loss due to partial diversity is effectively compensated by the concatenation of turbo coding. Simulation results show that on the condition of the same system throughput and concatenation of turbo code, the proposed scheme has lower bit error rate (BER) than those low-rate and full-diversity multiple antennas STB coding schemes.

A weighted Euclidean distance method for rural settlements traffic location evaluation

2007 ◽  
Author(s):  
Tongkun Wang ◽  
Zhenjie Chen ◽  
Dong Chen ◽  
Mingchao Jia
Keyword(s):  
Euclidean Distance ◽  
Rural Settlements ◽  
Distance Method

Auto White Balance Algorithm in Digital Camera

2012 ◽  
Vol 182-183 ◽  
pp. 2080-2084
Author(s):  
Jie Li ◽  
Xue Xiang Wang ◽  
Hao Liu
Keyword(s):  
Hardware Implementation ◽  
Digital Camera ◽  
Low Complexity ◽  
Light Sources ◽  
Light Conditions ◽  
Threshold Method ◽  
White Balance ◽  
White Point ◽  
A New Technique ◽  
Better Than

Auto white balance (AWB) is an important function of digital camera. The purpose of white balance is to adjust the image to make it look like taken under standard light conditions. We present a new technique to detect the reference white point of image in this paper. This technique detects the white point of image by using dynamic threshold method, thus making it more flexible and more applicable compared to other algorithms. We test 50 images which were taken under different light sources, and find that this algorithm is better than or comparable to other algorithms both in subjective and objective aspects. At the same time, this algorithm has low complexity, and it can be easily applied to hardware implementation.

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