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1
Rathod, Anokchand, and Megha Gupta. "Review Paper on MIMO-OFDM System Using Wimax Model." International Journal of Trend in Scientific Research and Development Volume-2, Issue-4 (June 30, 2018): 2259–63. http://dx.doi.org/10.31142/ijtsrd14604.
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Youssef, M. I., A. E. Emam, and M. Abd Khalifa. "ICI and PAPR enhancement in MIMO-OFDM system using RNS coding." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 2 (April 1, 2019): 1209. http://dx.doi.org/10.11591/ijece.v9i2.pp1209-1219.
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<p><span>The Inter-Carrier-Interference (ICI) is considered a bottleneck in the utilization of Multiple-Input-Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems, due to the sensitivity of the OFDM towards frequency offsets which lead to loss of orthogonality, interference and performance degradation. In this paper Residue Numbers as a coding scheme is impeded in MIMO-OFDM systems, where the ICI levels is measured and evaluated with respect to conventional ICI mitigation techniques implemented in MIMO-OFDM. The Carrier-to-Interference Ratio (CIR), the system Bit-Error-Rate (BER) and the Complementary Cumulative Distribution Function (CCDF) for MIMO-OFDM system with Residue Number System (RNS) coding are analyzed and evaluated. The results had demonstrated a performance of transmission model with and without RNS.</span></p>
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N. Jayanthi, P., and S. Ravishankar. "Model-based compressed sensing algorithms for MIMO- OFDM channel estimation." International Journal of Engineering & Technology 7, no. 2.4 (March 10, 2018): 5. http://dx.doi.org/10.14419/ijet.v7i2.4.10030.
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High data rates on the wireless channel can be achieved by combining orthogonal frequency division multiplexing (OFDM) with multiple input multiple output (MIMO) communication modulation scheme. MIMO-OFDM system impulse response of the channel is approximately sparse. Sparse channelestimation can be done using Compressive Sensing (CS) techniques. In this paper, a low complexity model based CoSaMp Compressive Sensing (CS) algorithm with conventional tools namely Least Square (LS) and Least Mean Square (LMS) are used for MIMO-OFDM channel estimation. Simulation results show amodel based CoSaMP for MIMO-OFDM channel estimation with LMS tool the Normalized Mean Square Error(NMSE)reduced by 34%with very reduced complexity.
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El Ghzaoui, M., A. Hmamou, J. Foshi, and J. Mestoui. "Compensation of Non-linear Distortion Effects in MIMO-OFDM Systems Using Constant Envelope OFDM for 5G Applications." Journal of Circuits, Systems and Computers 29, no. 16 (June 18, 2020): 2050257. http://dx.doi.org/10.1142/s0218126620502576.
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Orthogonal frequency division multiplexing (OFDM) is a multicarrier transmission system that can achieve high data rate over wireless channels. At the same time, multiple input multiple output OFDM (MIMO-OFDM) in wireless communication systems has been exposed to offer significant improvement over wireless technology by providing transmit diversity. It has become a promising technique for high-performance 5G broadband wireless communications. However, the main problem associated with MIMO-OFDM is that its signal exhibits high peak-to-average power ratio (PAPR), which causes nonlinear distortion and consequently performance degradation. Besides, PAPR carries weaknesses such as an increase in power consumption of high power amplifier (HPA) and analog to digital converter (ADC). Thus, 5G base stations will push up power requirements because energy consumption grows with the number of transceiver elements. So, mobile operators must find the right compromise that, on the one hand, guarantees a certain level of performance to a data flow, and, on the other hand, the energy cost generated for the deployment of the network. For this, as part of the management of power consumption, we propose MIMO constant envelope OFDM (MIMO-CE-OFDM) technique. In this work, we used MIMO-CE-OFDM to mitigate the nonlinear effect of HPA and ADC. To perform practical simulations, we have used COST 2100 MIMO channel model. In this paper, a MIMO-CE-OFDM system has been presented and analyzed under COST 2100 channel model conditions. Simulation results are given to illustrate the performance of [Formula: see text] MIMO-CE-OFDM in the presence of both HPA and ADC nonlinearity. This work shows that the effect of nonlinearity is shown to be negligible on MIMO-CE-OFDM signal.
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Shivhare, Amit, Ravi Kumar, and Manish K. Patidar. "Review of MIMO-OFDM System Using Simulink Model." International Journal of Computer Sciences and Engineering 7, no. 3 (March 31, 2019): 72–75. http://dx.doi.org/10.26438/ijcse/v7i3.7275.
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Et. al., Preesat Biswas,. "A Simulational Performance of 5G MIMO Systems applying UFMC( Universal Filtered Multicarrier) Study." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 2 (April 10, 2021): 3176–83. http://dx.doi.org/10.17762/turcomat.v12i2.2365.
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The advanced wireless communication system uses the new technology, preparing the limited radio spectrum and its low expensive resource. The Scenario of Wireless communication is needed for the flexible mechanism with available time and frequency resources. The OFDM system, which is a multicarrier process with a remote framework in Long Term Evolution (LTE), 4G, and 5G. Using of UFMC(Universal_Filtered_Multicarrier)system with OFDM system symmetrical recurrence division multiply with modulation system and the correlation between them. Using of UFMC system with QAM into the MIMO system the result of subchannel, the model channel correlation recreated in “ A Simulational Performance of 5G MIMO Systems applying UFMC (Universal_Filtered_Multicarrier ) Study” result shown in MATLAB.
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Silpa, C., A. Vani, and K. Rama Naidu. "Deep Learning Based Channel Estimation for MIMO-OFDM System with Modified ResNet Model." Indian Journal Of Science And Technology 16, no. 2 (January 15, 2023): 97–108. http://dx.doi.org/10.17485/ijst/v16i2.2154.
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Kavitha, G., B. Kirthiga, and N. Kirubanandasarathy. "Performance Analysis of an Area Efficient and Low Power MOD-R2MDC FFT for MIMO OFDM." Applied Mechanics and Materials 573 (June 2014): 176–80. http://dx.doi.org/10.4028/www.scientific.net/amm.573.176.
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In this paper, an area-efficient low power fast fourier transform (FFT) processor is proposed for multi input multi output-orthogonal frequency division multiplexing (MIMO-OFDM) in wireless communication system. It consists of a modified architecture of radix-2 algorithm which is described as modified radix-2 multipath delay commutation (MOD-R2MDC). The OFDM receiver with modified R2MDC (MOD-R2MDC) FFT was designed by Hardware Description Language (HDL) coding The Xilinx ISE Design Suite 10.1 is used as a synthesis tool for getting the power and area. The Model-Sim 6.3c is used for simulation. Also the existing OFDM system has been tested with these FFT algorithms and their performances were analyzed with respect to occupancy area in FPGA and power consumption. A low-power and area efficient architecture enables the real-time operations of MIMO OFDM system.
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Zhao, Gaoli, Jianping Wang, Wei Chen, and Junping Song. "A Novel Signal Detection Algorithm for Underwater MIMO-OFDM Systems Based on Generalized MMSE." Journal of Sensors 2019 (November 12, 2019): 1–10. http://dx.doi.org/10.1155/2019/2603051.
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The MIMO-OFDM system fully exploits the advantages of MIMO and OFDM, effectively resisting the channel multipath fading and inter-symbol interference while increasing the data transmission rate. Studies show that it is the principal technical mean for building underwater acoustic networks (UANs) of high performance. As the core, a signal detection algorithm determines the performance and complexity of the MIMO-OFDM system. However, low computational complexity and high performance cannot be achieved simultaneously, especially for UANs with a narrow bandwidth and limited data rate. This paper presents a novel signal detection algorithm based on generalized MMSE. First, we propose a model for the underwater MIMO-OFDM system. Second, we design a signal coding method based on STBC (space-time block coding). Third, we realize the detection algorithm namely GMMSE (generalized minimum mean square error). Finally, we perform a comparison of the algorithm with ZF (Zero Forcing), MMSE (minimum mean square error), and ML (Maximum Likelihood) in terms of the BER (bit error rate) and the CC (computational complexity). The simulation results show that the BER of GMMSE is the lowest one and the CC close to that of ZF, which achieves a tradeoff between the complexity and performance. This work provides essential theoretical and technical support for implementing UANs of high performance.
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Shobha, Y. K., and H. G. Rangaraju. "Experimental Evaluation of Machine learning based MIMO-OFDM System for Optimal PAPR and BER." WSEAS TRANSACTIONS ON SYSTEMS AND CONTROL 16 (May 26, 2021): 315–27. http://dx.doi.org/10.37394/23203.2021.16.27.
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The hypothetically convenient structure is the Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) technique that is employed for upcoming generations in wireless communication systems. Some of the benefits offered by MIMO-OFDM are enhanced spatial multiplexing, reliability and network throughput, and so on. Due to the integration of spatial antenna that is based on multi-stream, the problems which are related to significantly high power takes place in the system of OFDM and provides complex processing strategies. Some of the popularly known systems that are used for standardizing the Peak to average power ratio (PAPR) are partial transmit sequences (PTS), adoptive tone reservation (ATR), probabilistic mapping, and clipping which are required to be truncated and aims for minimizing the operational cost. The framework of hybrid Selective Mapping (SLM)-PTS proposed in this paper minimizes the operational cost by integrating strategies of PTS and SLM. A reduction approach that is suitable for PAPR and BER are chosen for optimization purposes depending on the statistical threshold constraint of PAPR and Bit Error Rate (BER). Thus, the system preferred with the help of the machine learning technique demonstrates the efficiency in implementing a generalized strategy to evaluate a low complexity MIMO-OFDM model. Ultimately, with the help of the PAPR and BER techniques-driven from value bound the performance of the error rate is evaluated in this framework that interactively changes from one technique.
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Palle Jagadeeswara Rao and Dr. A S Srinivasa Rao. "PAPR Reduction of OFDM System with Biorthoganoal Wavelet Transforms." International Journal for Modern Trends in Science and Technology, no. 02 (February 12, 2021): 17–22. http://dx.doi.org/10.46501/ijmtst0702004.
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Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input and Multiple Output (MIMO) are two main techniques employed in 4th Generation Long Term Evolution (LTE). In OFDM multiple carriers are used and it provides higher level of spectral efficiency as compared to Frequency Division Multiplexing (FDM). In OFDM because of loss of orthogonality between the subcarriers there is intercarrier interference (ICI) and intersymbol interference (ISI) and to overcome this problem use of cyclic prefixing (CP) is required, which uses 20% of available bandwidth. Wavelet based OFDM provides good orthogonality and with its use Bit Error Rate (BER) is improved. Wavelet based system does not require cyclic prefix, so spectrum efficiency is increased. It is proposed to use wavelet transform including biorthoganoal wavelet transform with OFDM systems. This approach will reduce PAPR in the OFDM system effectively. We will design this model with different modulation Techniques like QPSK and QAM and compare the BER results.
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Youssif, Mohamed Ibrahim, Amr ElSayed Emam, and Mohamed Abd ElGhany. "Image multiplexing using residue number system coding over MIMO-OFDM communication system." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 6 (December 1, 2019): 4815. http://dx.doi.org/10.11591/ijece.v9i6.pp4815-4825.
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<p>Image transmission over Orthogonal Frequency-Division Multiplexing (OFDM) communication system is prone to distortion and noise due to the encountered High-Peak-to-Average-Power-Ratio (PAPR) generated from the OFDM block. This paper studies the utilization of Residue Number System (RNS) as a coding scheme for digital image transmission over Multiple-Input-Multiple-Output (MIMO) – OFDM transceiver communication system. The use of the independent parallel feature of RNS, as well as the reduced signal amplitude to convert the input signal to parallel smaller residue signals, enable to reduce the signal PAPR, decreasing the signal distortion and the Bit Error Rate (BER). Consequently, improving the received Signal-to-Noise Ratio (SNR) and enhancing the received image quality. The performance analyzed though BER, and PAPR. Moreover, image quality measurement is achieved through evaluating the Mean Squared Error (MSE), Peak Signal to Noise Ratio (PSNR), and the correlation values between the initial and retrieved images. Simulation results had shown the performance of transmission/reception model with and without RNS coding implementation.</p><p> </p>
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Singal, Anuj, and Deepak Kedia. "Energy Efficiency Analysis of Antenna Selection Techniques in Massive MIMO-OFDM System with Hardware Impairments." Journal of Computer Networks and Communications 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/6131247.
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In massive multiple-input multiple-output (M-MIMO) systems, a large number of antennas increase system complexity as well as the cost of hardware. In this paper, we propose an M-MIMO-OFDM model using per-subcarrier antenna selection and bulk antenna selection schemes to mitigate these problems. Also, we derive a new uplink and downlink energy efficiency (EE) equation for the M-MIMO-OFDM system by taking into consideration the antenna selection schemes, power scaling factor (g=0.25, 0.5), and a range of hardware impairments {κBS, κUEϵ (0, 0.052, 0.12)}. In addition, we investigate a trend of EE by varying various parameters like number of base station antennas (BSAs), SNR, level of hardware impairments, total circuit power consumption, power optimization, antenna selection schemes, and power scaling factor in the proposed M-MIMO-OFDM model. The simulation results thus obtained show that the EE increases with increase in the value of SNR. Also, it increases abruptly up to 100 number of BSA. However, the increase in the EE is not significant in the range of 125 to 400 number of BSA. Further, the bulk antenna selection technique has comparatively more EE than the per-subcarrier antenna selection. Moreover, EE gaps between antenna selection schemes decrease with increase in the value of hardware impairments and power scaling factor. However, as the hardware degradation effect increases, the EE of the bulk antenna selection scheme suffers more degradation as compared to the Per-subcarrier antenna selection scheme. It has also been observed that EE performance is inversely proportional to the total circuit power consumption (λ+γ) and it increases with the power optimization.
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Baktash, Ebrahim, Chi-Heng Lin, Xiaodong Wang, and Mahmood Karimi. "Downlink Linear Precoders Based on Statistical CSI for Multicell MIMO-OFDM." Wireless Communications and Mobile Computing 2017 (2017): 1–18. http://dx.doi.org/10.1155/2017/5981659.
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With 5G communication systems on the horizon, efficient interference management in heterogeneous multicell networks is more vital than ever. This paper investigates the linear precoder design for downlink multicell multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems, where base stations (BSs) coordinate to reduce the interference across space and frequency. In order to minimize the overall feedback overhead in next-generation systems, we consider precoding schemes that require statistical channel state information (CSI) only. We apply the random matrix theory to approximate the ergodic weighted sum rate of the system with a closed form expression. After formulating the approximation for general channels, we reduce the results to a more compact form using the Kronecker channel model for which several multicarrier concepts such as frequency selectivity, channel tap correlations, and intercarrier interference (ICI) are rigorously represented. We find the local optimal solution for the maximization of the approximate rate using a gradient method that requires only the covariance structure of the MIMO-OFDM channels. Within this covariance structure are the channel tap correlations and ICI information, both of which are taken into consideration in the precoder design. Simulation results show that the rate approximation is very accurate even for very small MIMO-OFDM systems and the proposed method converges rapidly to a near-optimal solution that competes with networked MIMO and precoders based on instantaneous full CSI.
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Sinha, Shivaji, Chakresh Kumar, Ammar Armghan, Mehtab Singh, Meshari Alsharari, and Khaled Aliqab. "Capacity Enhancement Analysis of an OAM-OFDM-SMM Multiplexed Free Space Communication System in Atmospheric Turbulence." Applied Sciences 13, no. 6 (March 19, 2023): 3897. http://dx.doi.org/10.3390/app13063897.
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To overcome atmospheric turbulence (AT) distortion during signal propagation through the optical link, orbital angular momentum (OAM) mode states employing multiple inputs and multiple outputs (MIMO) techniques have recently gained prominence in free space optical communication (FSO). As the various OAM modes propagate through the free space optical link, signal attenuation and crosstalk may occur, reducing system capacity and increasing the likelihood of bit errors. In this work, our objective is to propose a spectrally efficient, high-speed and channel capacity efficient crosstalk FSO communication system by combining the features of orthogonal frequency division multiplexing (OFDM), spatial mode multiplexing (SMM), and a mode diversity scheme into an existing OAM-FSO communication system. The incorporation of the OFDM-MIMO concept and spatial mode diversity into the existing OAM-MIMO-FSO system is extremely beneficial in enhancing the transmission capacity, mitigating multipath fading and atmospheric turbulence distortions. The Gamma–Gamma (GG) model is used to assess the performance of the proposed system under various atmospheric turbulence conditions in terms of the performance metrics such as BER vs. number of OAM states for different refractive index structure and Rytov constants, link distance, and an optical signal to noise ratio (OSNR). A FEC limit of 3.8 × 10−3 and a maximum link distance of 2 km are set to evaluate these performance parameters. Finally, the transmission capacity of the proposed system is compared to that of the existing MIMO and OAM-SMM-MIMO systems for different OSNR values under atmospheric turbulence conditions for the OAM state of l = +1, yielding an overall improvement of 3.3 bits/s/Hz compared to conventional MIMO systems and 1.6 bits/s/Hz for the OAM-SMM-MIMO system.
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Chowdhuri, Swati, Sayan Chakraborty, Nilanjan Dey, Ahmad Taher Azar, Mohammed Abdel-Megeed M. Salem, Sheli Sinha Chaudhury, and Pranab Banerjee. "Recent Research on Multi Input Multi Output (MIMO) based Mobile ad hoc Network." International Journal of Service Science, Management, Engineering, and Technology 5, no. 3 (July 2014): 54–65. http://dx.doi.org/10.4018/ijssmet.2014070104.
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Mobile ad hoc Network (MANET) and Multi Input Multi Output (MIMO) communication are emerging techniques in modern communication system. MIMO and MANET have various applications in the wireless communication system. This paper presents a survey on recent advancement of MIMO implemented mobile ad hoc network. A review of more than 40 papers on MIMO communication based mobile ad hoc network and most of the related topics is presented in this work. This paper shows the significant contribution in the field of MIMO communication and mobile ad hoc network. Previous works in this domain can be categorized into four major areas: (a) Mathematical modeling of MIMO channel and Ad hoc networks, (b) Physical Scattering Model of MIMO channel considering fading (c) Spatial multiplexing (OFDM) technique with MIMO channel, (d) Analysis of transmission efficiency of packet radio network. The review paper establishes the advancement in these four areas as well as recent changes in advance communication and networking environments.
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Azeez, Abdul, and Suraiya Tarannum. "Multi-Objective Mayfly Optimization in Phase Optimization of OFDM." IIUM Engineering Journal 24, no. 1 (January 4, 2023): 106–21. http://dx.doi.org/10.31436/iiumej.v24i1.2625.
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Communication systems have been used tremendously in recent years which results in the need for high data transmission rates. Orthogonal Frequency Division Multiplexing (OFDM) provides robust performance in frequency selective fading due to high bandwidth efficiency and inter-symbol interference. Various optimization techniques were applied in existing research to increase the efficiency of OFDM in a communication system. The existing research has a limitation of considering a single objective to improve the efficiency of OFDM and also has a local optima trap. This research proposes a Multi-Objective Mayfly algorithm (MOMF) to consider multi-objective and provides a proper trade-off between exploration and exploitation. The Partial Transmit Sequence (PTS) is applied in the model to test the performance. The FFT sizes and modulation orders are varied to evaluate the performance of the MOMF technique in phase optimization. The MOMF technique effectively increases the performance of the model than other existing optimization techniques. The MOMF technique provides a non-dominated solution to escape from local optima trap. The MOMF model considers PAPR, BER, and SER in MIMO-OFDM system to increase the efficiency of the system. The exploration-exploitation trade-off helps to improve the convergence and overcome local optima trap. The MOMF in OFDM phase optimization was evaluated using BER, SER, and Peak-to-Average Power Ratio (PAPR) metrics. The MOMF method has PAPR of 3.95 dB and PSO-GWO method has 4.92 dB of PAPR. ABSTRAK: Sistem komunikasi telah digunakan secara meluas sejak beberapa tahun ini dan dapatan kajian menunjukkan keperluan pada kadar transmisi data yang tinggi. Pemultipleksan Bahagian Frekuensi Ortogon (OFDM) menyediakan prestasi berkesan dalam pemilihan pemudaran frekuensi berdasarkan keberkesanan lebar jalur tinggi dan gangguan antara-simbol. Pelbagai teknik optimum digunakan pada kajian sebelum ini bagi meningkatkan keberkesanan OFDM dalam sistem komunikasi. Kajian tersebut mempunyai kekurangan dalam memilih satu objektif bagi membaiki keberkesanan OFDM dan juga mempunyai perangkap optima setempat. Kajian ini mencadangkan algoritma Mayfly Objektif-Pelbagai (MOMF) bagi memilih objektif-pelbagai dan menyediakan keseimbangan yang wajar antara eksplorasi dan eksploitasi. Urutan Pancar Separa (PTS) telah digunakan dalam model ini bagi menguji prestasi. Saiz FFT dan turutan modulasi dipelbagaikan bagi menguji keberkesanan teknik MOMF pada fasa pengoptimuman. Teknik MOMF dengan berkesan menaikkan prestasi model ini berbanding teknik-teknik sedia ada yang lain. Teknik MOMF menyediakan solusi kepada teknik bukan-dominasi bagi mengelak perangkap optima setempat. Model MOMF ini mengambil kira PAPR, BER, dan SER dalam sistem MIMO-OFDM bagi meningkatkan kecekapan sistem. Keseimbangan yang wajar antara eksplorasi-eksploitasi membantu dalam membaiki penumpuan dan mengatasi perangkap optima setempat. MOMF dalam fasa optimanisasi OFDM telah dinilai menggunakan BER, SER, dan matrik Nisbah Kuasa Puncak-kepada-Purata (PAPR). Kaedah MOMF mempunyai nilai PAPR sebanyak 3.95 dB dan kaedah PSO-GWO mempunyai PAPR 4.92 dB.
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Joseph, Nisha Mary, and Puttamadappa C. "Highly Accurate Technique for CO-OFDM Channel Estimation Technique Using Extreme Learning Machine (ELM)." WSEAS TRANSACTIONS ON ELECTRONICS 14 (March 9, 2023): 7–23. http://dx.doi.org/10.37394/232017.2023.14.2.
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In wireless systems, channel estimation is considered a problematic technology, due to the fact of the difference in time between wireless channels and the noise effect. Orthogonal frequency-division multiplexing (OFDM) is a promising candidate for future optical communications and has received wide concern. The article proposed a Coherent Optical (CO) orthogonal frequency division multiplexing (OFDM) scheme, which gives a scalable and flexible solution for increasing the transmission rate, being extremely robust to chromatic dispersion as well as polarization mode dispersion. Nevertheless, both coherent detection and OFDM are prone to phase noise due to the phase mismatch between the laser oscillators at the transmitter and receiver sides and the relatively long OFDM symbol duration compared to that of single carrier communications. An Extreme Learning Machine (ELM) with Pilot Assisted Equalization (PEM) is proposed for compensation of impairments caused by fibre nonlinearity in coherent optical communication systems. Channel estimation using ELM and the value of distortion is sent to the OSTBC receiving end based on the distortion information the data is decoded and pilot data is removed. FFT is applied to the data and QPSK demodulation is done in the data to get its original form. In addition, the article utilized a free-space optical communication system of multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) with a modified receiver structure. Simulation reveals that the proposed model exhibits significant BER (0.0112) performance and provides better spectral efficiency as compared with conventional systems and less computational complexity. This suggested that the proposed method shows better performance by using the CO-OFDM-FSO-MIMO-ELM-based channel estimation technique for high-speed data communication networks in real-time scenarios respectively.
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Singal, Anuj, and Deepak Kedia. "Performance Analysis of Antenna Selection Techniques in MIMO-OFDM System with Hardware Impairments: Energy Efficiency perspective." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 4 (August 1, 2018): 2272. http://dx.doi.org/10.11591/ijece.v8i4.pp2272-2279.
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<p>In this paper we propose a new MIMO-OFDM model in which we consider various antenna selection techniques like Bulk selection and Per-subcarrier selection etc. with hardware impairments such as non-linearties of amplifiers, quantization noise, phase noise and I-Q imbalance etc. As we know that the transceiver hardware impairments limit the channel capacity and the energy efficiency of MIMO-OFDM system, so we can not neglect the fundamental impacts of these hardware impairments {Kappa (0.05 0.1)} on the energy efficiency in the high SNR domain. Therefore we analyze the Energy Efficiency of Bulk and Per-subcarrier antenna selection techniques with or without hardware impairments. It has been observed that the energy efficiency decreases as the value of these hardware impairments increases. As we compared the Bulk antenna selection with the Per-subcarrier antenna selection scheme, the Per-subcarrier antenna selection requires more number of RF (radio frequency) chains and transmits power in comparison to the Bulk selection. Due to this, the Bulk antenna selection technique is more energy efficient than Per-subcarrier antenna selection.</p>
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Jiang, Hao, and Hongming Chen. "A Full-Duplex MIMO System Based on CP-Free OFDM in Sensor Network." Journal of Sensors 2022 (July 11, 2022): 1–5. http://dx.doi.org/10.1155/2022/6888809.
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Recently, results have shown that full-duplex (FD) system based on orthogonal frequency division multiplexing (OFDM) is potential for wireless sensor networks. However, extending FD to further improve spectral efficiency by removing cyclic prefix (CP) with optimal canceling self-interference (SI) remains a challenge. In this paper, we analytically study the conventional FD OFDM system and proposed a CP-free system on this basis. The key point of the proposed scheme is the symbols transmitted in a unit of two identical symbols without CP. To eliminate the intersymbol interference, the disturbed part are replaced by the repeated signal at the receiver, which has the same effect as CP. Finally, an SI cancellation is down to restore the transmitted symbols. As a key of analysis, a multiple-input multiple-output (MIMO) FD simulation model is carried to show that our proposed scheme is effectiveness in terms of the bit error ratio (BER).
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Zhou, Yang, Hong Cheng Dong, and Xiao Wen Li. "An Improved SVD-LMMSE Channel Estimation Algorithm of LTE System." Advanced Materials Research 756-759 (September 2013): 862–66. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.862.
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This paper first introduces the MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) system model, and then studies several classical channel estimation algorithms: LS (Least Square) algorithm, LMMSE (Liner Minimum Mean-Square Error) algorithms and SVD-LMMSE (Singular value decomposition) algorithm. Finally, based on the DCT transform domain channel estimation, the original SVD-LMMSE algorithm has been improved. Theoretical analysis and simulation results show that: The improved SVD-LMMSE algorithm not only can reduce the complexity of the implementation, but also has more superior performance.
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Zhao, Yuzhen, Longyong Chen, Fubo Zhang, Yanlei Li, and Yirong Wu. "A Novel MIMO-SAR System Based on Simultaneous Digital Beam Forming of Both Transceiver and Receiver." Sensors 20, no. 22 (November 18, 2020): 6604. http://dx.doi.org/10.3390/s20226604.
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Orthogonal frequency division multiplexing (OFDM) chirp waveform, which is composed of two or more successive identical linear frequency modulated sub pulses, is a newly proposed orthogonal waveform scheme for multi-input multi-output (MIMO) synthetic aperture radar (SAR) systems. However, according to the waveform model, there will be range ambiguity if the mapping width exceeds the maximum unambiguous width determined by the transmitted signal. This greatly limits its application in high-resolution wide-swath (HRWS) remote sensing. The traditional system divides the echoes by digital beam forming (DBF) to solve this problem, but the energy utilization rate is low. A MIMO-SAR system using simultaneous digital beam forming of both transceiver and receiver to avoid range ambiguity is designed in this paper. Compared with traditional system, the novel system designed in this paper obtain higher energy utilization and waveform orthogonality.
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Ha, Chang-Bin, Young-Hwan You, and Hyoung-Kyu Song. "Machine Learning Model for Adaptive Modulation of Multi-Stream in MIMO-OFDM System." IEEE Access 7 (2019): 5141–52. http://dx.doi.org/10.1109/access.2018.2889076.
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Shareef, Faez Fawwaz, and Manal Jamil Al-Kindi. "Wideband hybrid precoder for mmWave multiuser MIMO OFDM communications." Bulletin of Electrical Engineering and Informatics 11, no. 3 (June 1, 2022): 1409–17. http://dx.doi.org/10.11591/eei.v11i3.3551.
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Using millimeter wave (mmWave) transmission for massive multiple input multiple output (MIMO) system can improve system performance and effectively reduce the size of the massive antennas array. However, A wideband beamformer design is needed to take advantage of this wideband channel. In this paper, a downlink multi-user massive MIMO orthogonal frequency division multiplexing (MIMO OFDM) system for mmWave communications is proposed. Each subcarrier channel can be approximated as a narrowband clustered channel, so a narrowband precoder can be applied for each subchannel. The hybrid precoder is implemented in a manner so the digital precoder is obtained for each subcarrier, whilst the analog precoder is common for all subcarriers. A modified “joint spatial division/multiplexing” (JSDM) scheme is used to design the precoder, where each user equipped with more than one antenna. The design of the analog precoder is based on the second order channel statistics to reduce the overhead information need to process and fed back and the subcarrier baseband precoder based on the instantaneous channel state information (CSI). Following the approach of Kronecker channel model, the iteration between the analog beamformers design at both end of link can be avoided. Finally testing the system using various numbers of antennas at base station.
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Praba, N., and K. M. Ravikumar. "PAPR Reduction at Large Multi-User-MIMO-OFDM using Adaptive Data Detection Algorithm." Indonesian Journal of Electrical Engineering and Computer Science 12, no. 3 (December 1, 2018): 1071. http://dx.doi.org/10.11591/ijeecs.v12.i3.pp1071-1080.
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<span>Wireless communication in present era contains large-scale MIMO network architecture that need to deliver an optimize-QoS to multi-user (MU). <br /> The optimize data rate transmission in massive MU-MIMO wireless systems is one of the most difficult task due to the extremely high implementation complexity. The practical wireless system channels generally exhibits the PAPR and frequency selective fading, it is also necessary to have a precoding solution in PAPR for the selected desirable channels. A solution for the designed problem of a noble error-correcting code for OFDM process with a low PAPR, in the case of impulse noise should be considered. In this paper, Adaptive-Data-detection (ADD) algorithm is proposed to obtain lower-complexity data-detection that corresponds to high throughput design and impulse noise removal for large MUI-MIMO wireless systems by the OFDM modulation technique. That contains some steps such as; initialization, <br /> pre-processing and equalization steps in order to get no performance loss and to minimalize the recurrent amount at each iterations during operation. In order to use simplify model, here we assume suitably perfect synchronization, large cyclic prefix and perfect-CSI (channel-state-information) which has been developed through the pilot depended training. Simulation results analysis show the proposed method substantial improvement over the existing algorithm in terms of both ‘Error-rate’ minimization and PAPR reduction.</span>
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Varade, Dr Suchita W. "Design of a Reduced BER Millimetre Waves Model using MIMO and OFDM Communication System." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (June 14, 2021): 748–54. http://dx.doi.org/10.22214/ijraset.2021.35078.
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The motivation behind this paper is to present another technique for isolating remote correspondence, (for example, the 802.11a/b/g/n and cell UMTS MAC conventions) across numerous problematic correspondence joins (like Ethernet) utilizing milli meter waves MIMO correspondence. The object is to present the fitting equipment, programming, and framework design needed to give the premise to a remote framework (utilizing a 802.11a/b/g/n and cell conventions as a model) that can scale to help a huge number of clients at the same time (say in a huge place of business, super corporate retailer, and so forth) or in a little, however extremely thick correspondence RF area. Components of correspondence between a base station and a Mobile Station will be examined measurably to exhibit higher throughput, less crashes and lower bit mistake rates (BER) with the given transmission capacity characterized by the 802.11n remote detail (utilization of MIMO channels will be assessed). Another organization nodal worldview will be introduced. Elective connection layer correspondence strategies will be suggested and broke down for the impact on cell phones. The examination will depict how the calculations utilized by state machines executed on Mobile Stations and Wi-Fi customer gadgets will be impacted by new base station transmission conduct. New equipment plan strategies that can be utilized to improve this engineering just as equipment plan standards concerning the insignificant equipment practical squares needed to help such a framework configuration will be portrayed. Recreation plan and check reproduction procedures to demonstrate the plan will oblige a worthy degree of execution to meet the exacting planning as it identifies with this new framework engineering.
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Guerreiro, João, Rui Dinis, and Luís Campos. "On the Achievable Capacity of MIMO-OFDM Systems in the CathLab Environment." Sensors 20, no. 3 (February 10, 2020): 938. http://dx.doi.org/10.3390/s20030938.
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In the last years, the evolution of digital communications has been harnessed by medical applications. In that context, wireless communications are preferable over wired communications, as they facilitate the work of health technicians by reducing cabling on the stretchers. However, the use of wireless communications is challenging, especially when high data rates and low latencies are required. In those scenarios, multiple-input multiple-output (MIMO) techniques might have an important role, thanks to the high capacity gains that they can exhibit, which ideally increase with the MIMO size. In this work, we study the propagation scenario of a typical medical laboratory through ray-tracing techniques. By taking into account the derived channel model, we study the potential of MIMO techniques in an IEEE 802.11ax environment. Through a set of performance results regarding the system capacity, we show that the MIMO gains might not be as high as supposed in the medical laboratory, being far from the ideal scenario. Therefore, the large data rates required by the modern medical imaging applications might only be achieved with a combination of MIMO systems and large bandwidths.
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Mogylevych, Dmytro, and Liudmyla Pogrebniak. "Analytical model OFDM-MIMO signal in a radio channel with frequency-time selective fading." Collection "Information Technology and Security" 11, no. 1 (June 29, 2023): 39–46. http://dx.doi.org/10.20535/2411-1031.2023.11.1.283538.
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One of the main problems in modern wireless electronic communication networks is the transmission and reception of signals in multipath propagation. Due to the imperfect impulse response of the communication channel, frequency-selective fading of the transmitted signal occurs. This can cause waveform distortion and inter-symbol interference, which can seriously degrade the performance of the communication system. Thus, increasing the noise immunity of wireless electronic communication networks in real-world conditions is one of the most important tasks of modern communication technologies. Orthogonal frequency division multiplexing is known for its resistance to multipath fading and is used to reduce the impact of inter-symbol interference. Multi-antenna systems are a key technology for increasing bandwidth and improving communication reliability. The combination of these two technologies in wireless electronic communication networks can reduce the impact of negative phenomena on the transmitted signal in difficult interference conditions. An analytical model of the signal transmitted by a nonstationary frequency-selective radio channel in a wireless electronic communication network with orthogonal frequency multiplexing and a multi-antenna system is proposed. Analytical expressions are presented that allow us to jointly take into account the influence of interchannel and inter-symbol interference (the effect of multipath signal propagation and Doppler shift on the transmitted signal) against the background of fluctuating noise. Taking into account the factors affecting the transmitted signal makes it possible to bring the model closer to the real processes that occur in the vast majority of radio channels of wireless electronic communication networks.
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Бреславец, Алексей Андреевич, and Александр Владимирович Тоцкий. "ИССЛЕДОВАНИЕ ЗАМИРАНИЙ В СИСТЕМЕ СВЯЗИ С ИСПОЛЬЗОВАНИЕМ ТЕХНОЛОГИИ OFDM." RADIOELECTRONIC AND COMPUTER SYSTEMS, no. 1 (February 23, 2018): 47–53. http://dx.doi.org/10.32620/reks.2018.1.06.
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A new technique exploited for estimating of fading influence in multipath signal propagation environment for communication system using OFDM (Orthogonal frequency-division multiplexing) technology is proposed. Rayleigh fading model is considered and studied in suggested approach. Wi-Fi network has been selected as a basis system for study performance of OFDM communication system operating in multipath and noisy communication channel. Preliminary experimental measurements and computations have been carried out in order to evaluate received signal parameters after test signal propagation through multipath communication link contaminating transmitted signal under influence of random Rayleigh fading. An algorithm has been developed that makes it possible to perform computations according considered model. Software corresponding to suggested algorithm has been developed. Proposed software contains user interface that is written in order to automate the process of computations. Developed software was examined experimentally for statistical study of interference behavior and its influence on the OFDM communication system performance. The following data were taking into account in investigations: Rayleigh fading; user's motion; number of operating OFDM subcarriers; number of receiving antennas; additive normal noise. The influence of these factors on the communication system performance was evaluated by computation the value of bit error rate (BER) values. Suggested software also gives an opportunity investigating the number of bit errors and appearance of the signal in the time and frequency domains at different stages of transmission. Computer simulations results were obtained for a sequence of test Monte Carlo runs depending on: the speed and angle of the user's traffic; the intensity of the additive Gaussian noise in communication channel; variations of the number of OFDM subcarriers; the number of antennas contained in the user equipment. Computer simulation results demonstrate the following: bit error rate values tend to increasing with increasing the user velocity as well with decreasing the number of antennas and subcarriers. It has been also shown decreasing the signal-to-noise ratio value under influence of additive noise with a Gaussian distribution according to decreasing the number of OFDM subcarriers and number of antennas in MIMO system.
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Waluyo, Catur Budi. "ANALISIS MIMO UNTUK PENINGKATAN KAPASITAS SISTEM SELULER 4G LTE PADA SISTEM KOMUNIKASI HIGH ALTITUDE PLATFORM STATION." Angkasa: Jurnal Ilmiah Bidang Teknologi 8, no. 2 (August 25, 2017): 111. http://dx.doi.org/10.28989/angkasa.v8i2.124.
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The development of technology has opened up a new wireless infrastructure to complement the satellite and terrestrial networks. High Altitude Platforms (HAPs) is a communications infrastructure that uses air balloon as a solution between terrestrial and satellite communications systems with medium coverage and low cost o f launching and maintenance. HAPs can be joined with a Long Term Evolution (LTE) technology standardized by the Third Generation Partnership Project (3GPP). LTE uses orthogonal frequency division multiplexing (OFDM) technology for downlink. OFDM technology is a technology that uses multicarrier and bring the data in parallel and the bandwidth is divided into several subcarrier. To improve the performance of LTE in an increase in capacity, coverage, and speed of data, then it can use MIMO techniques. MIMO is a technique using multiple antenna transmitter and receiver antennas that are used to overcome the problem of multipath fading and increase the capacity of the system to be serviced. MIMO support the achievement of high transmission speed. In the simulation, signals generated by the modified jakes model into a ricean channel using the K factor 1.41, 1.99, 2.33, 2.66, 4.61, 6.35, 9.21, 12.15, 16.77 dB with elevation angle of 1 0 ° to 90°. The larger the K factor, the smaller the shift doppler at each speed. Elevation angle have a relationship to the coverage area of HAPs, the smaller the elevation angle of the wider the coverage area, and the higher the position, the wider HAPs coverage area too. In ergodic capacity, the smaller the K factor, the smaller the elevation angle so that the capacity is also greater. System without estimation for the K factor o f 1.41dB and K 9.21dB is necessary for channel estimation and the Bit Error Rate (BER) o f the same system that made channel estimation has a better performance compared with the existing channel without estimation with the SNR improvement o f about 18 dB.
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Noorazlina, M. S., S. M. Sulong, M. Shahrizan M. Said, I. Ahmad, and A. Idris. "Design of MIMO F-OFDM System Model for PAPR Reduction in the Growth of 5G Network." Journal of Physics: Conference Series 1793, no. 1 (February 1, 2021): 012067. http://dx.doi.org/10.1088/1742-6596/1793/1/012067.
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Le, Ha An, Trinh Van Chien, Tien Hoa Nguyen, Hyunseung Choo, and Van Duc Nguyen. "Machine Learning-Based 5G-and-Beyond Channel Estimation for MIMO-OFDM Communication Systems." Sensors 21, no. 14 (July 16, 2021): 4861. http://dx.doi.org/10.3390/s21144861.
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Channel estimation plays a critical role in the system performance of wireless networks. In addition, deep learning has demonstrated significant improvements in enhancing the communication reliability and reducing the computational complexity of 5G-and-beyond networks. Even though least squares (LS) estimation is popularly used to obtain channel estimates due to its low cost without any prior statistical information regarding the channel, this method has relatively high estimation error. This paper proposes a new channel estimation architecture with the assistance of deep learning in order to improve the channel estimation obtained by the LS approach. Our goal is achieved by utilizing a MIMO (multiple-input multiple-output) system with a multi-path channel profile for simulations in 5G-and-beyond networks under the level of mobility expressed by the Doppler effects. The system model is constructed for an arbitrary number of transceiver antennas, while the machine learning module is generalized in the sense that an arbitrary neural network architecture can be exploited. Numerical results demonstrate the superiority of the proposed deep learning-based channel estimation framework over the other traditional channel estimation methods popularly used in previous works. In addition, bidirectional long short-term memory offers the best channel estimation quality and the lowest bit error ratio among the considered artificial neural network architectures.
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Hamedani, Kian, Lingjia Liu, Shiya Liu, Haibo He, and Yang Yi. "Deep Spiking Delayed Feedback Reservoirs and Its Application in Spectrum Sensing of MIMO-OFDM Dynamic Spectrum Sharing." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 02 (April 3, 2020): 1292–99. http://dx.doi.org/10.1609/aaai.v34i02.5484.
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In this paper, we introduce a deep spiking delayed feedback reservoir (DFR) model to combine DFR with spiking neuros: DFRs are a new type of recurrent neural networks (RNNs) that are able to capture the temporal correlations in time series while spiking neurons are energy-efficient and biologically plausible neurons models. The introduced deep spiking DFR model is energy-efficient and has the capability of analyzing time series signals. The corresponding field programmable gate arrays (FPGA)-based hardware implementation of such deep spiking DFR model is introduced and the underlying energy-efficiency and recourse utilization are evaluated. Various spike encoding schemes are explored and the optimal spike encoding scheme to analyze the time series has been identified. To be specific, we evaluate the performance of the introduced model using the spectrum occupancy time series data in MIMO-OFDM based cognitive radio (CR) in dynamic spectrum sharing (DSS) networks. In a MIMO-OFDM DSS system, available spectrum is very scarce and efficient utilization of spectrum is very essential. To improve the spectrum efficiency, the first step is to identify the frequency bands that are not utilized by the existing users so that a secondary user (SU) can use them for transmission. Due to the channel correlation as well as users' activities, there is a significant temporal correlation in the spectrum occupancy behavior of the frequency bands in different time slots. The introduced deep spiking DFR model is used to capture the temporal correlation of the spectrum occupancy time series and predict the idle/busy subcarriers in future time slots for potential spectrum access. Evaluation results suggest that our introduced model achieves higher area under curve (AUC) in the receiver operating characteristic (ROC) curve compared with the traditional energy detection-based strategies and the learning-based support vector machines (SVMs).
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Bawage, Sandeep, Manjula S, and A. M. Bhavikatti. "A performance enhancement of physical layer at Wi-MAX system with RLDPC code." Indonesian Journal of Electrical Engineering and Computer Science 21, no. 3 (March 10, 2021): 1557. http://dx.doi.org/10.11591/ijeecs.v21.i3.pp1557-1566.
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<span>In present wireless communication network, the error correction codes plays the major role for efficient data transmission in noisy environments. To get minimum BER and PAPR has been the main aim towards the field in forward error control coding. Majority of the researchers has considered turbo codes at specific SNR over AWGN channel but have complexity issues with the iterative output decoder and causes degradation in the Wi-Max network system. In this paper, the author presents and evaluates WiMAX physical layer performance with using MIMO technologies, where a Robust-LDPC technique of coding and decoding in OFDM based WiMAX system is consider. The decoding method of RLDPC has processed by Belief Propagation at the logarithmic domain in an iterative manner, the proposed methodology shows good decoding outcome for RLDPC codes at Rician and Rayleigh channel. Moreover, the applicability of our proposed model channel codes is defined under IEEE Wi-MAX standard and the results analysis is done under different code-rate and modulation schemes.</span>
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Sai Subramanyam Thoota, Dolores Garcia Marti, �zlem Tugfe Demir, Rakesh Mundlamuri, Joan Palacios, Cenk M. Yetis, Christo Kurisummoottil Thomas, et al. "Site-specific millimeter-wave compressive channel estimation algorithms with hybrid MIMO architectures." ITU Journal on Future and Evolving Technologies 2, no. 4 (July 14, 2021): 9–26. http://dx.doi.org/10.52953/oeeg5719.
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In this paper, we present and compare three novel model-cum-data-driven channel estimation procedures in a millimeter-wave Multi-Input Multi-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) wireless communication system. The transceivers employ a hybrid analog-digital architecture. We adapt techniques from a wide range of signal processing methods, such as detection and estimation theories, compressed sensing, and Bayesian inference, to learn the unknown virtual beamspace domain dictionary, as well as the delay-and-beamspace sparse channel. We train the model-based algorithms with a site-specific training dataset generated using a realistic ray tracing-based wireless channel simulation tool. We assess the performance of the proposed channel estimation algorithms with the same site's test data. We benchmark the performance of our novel procedures in terms of normalized mean squared error against an existing fast greedy method and empirically show that model-based approaches combined with data-driven customization unanimously outperform the state-of-the-art techniques by a large margin. The proposed algorithms were selected as the top three solutions in the "ML5G-PHY Channel Estimation Global Challenge 2020" organized by the International Telecommunication Union.
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Valle, Luis, Jesús R. Pérez, and Rafael P. Torres. "Characterisation of Indoor Massive MIMO Channels Using Ray-Tracing: A Case Study in the 3.2–4.0 GHz 5G Band." Electronics 9, no. 8 (August 4, 2020): 1250. http://dx.doi.org/10.3390/electronics9081250.
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In this paper, research results on the applicability of ray-tracing (RT) techniques to model massive MIMO (MaMi) channels are presented and discussed. The main goal is to show the possibilities that site-specific models based on rigorous RT techniques, along with measurement campaigns considered for verification or calibration purposes where appropriate, can contribute to the development and deployment of 5G systems and beyond using the MaMi technique. For this purpose, starting from the measurements and verification of the simulator in a symmetric, rectangular and accessible scenario used as the testbed, the analysis of a specific case involving channel characterisation in a large, difficult access and measurement scenario was carried out using the simulation tool. Both the measurement system and the simulations emulated the up-link in an indoor cell in the framework of a MaMi-TDD-OFDM system, considering that the base station was equipped with an array consisting of 10 × 10 antennas. The comparison of the simulations with the measurements in the testbed environment allowed us to affirm that the accuracy of the simulator was high, both for determining the parameters of temporal dispersion and frequency selectivity, and for assessing the expected capacity in a specific environment. The subsequent analysis of the target environment showed the high capacities that a MaMi system can achieve in indoor picocells with a relatively high number of simultaneously active users.
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Alsharari, Meshari, Khaled Aliqab, Farman Ali, and Ammar Armghan. "Integrated Free-Space Optics and Fiber Optic Network Performance Enhancement for Sustaining 5G High Capacity Communications." International Journal of Optics 2023 (January 13, 2023): 1–9. http://dx.doi.org/10.1155/2023/8685686.
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In this paper, the integrated free-space optics (FSO) and fiber optic model is evaluated using new radio (NR) sub-THz link to sustain next generation 5G capacity. The proposed integrated model effectively applies over 25 km single mode fiber, 0.5 m RF wireless, and 500 m optical wireless. In addition, four different sub-THz frequencies (125, 150, 175, and 200 GHz) are estimated on NR-based 5G FSO network, including 22 Gbps 64quadrature amplitude modulation-orthogonal frequency division multiplexing (64QAM-OFDM) signal speed. The proposed FSO enabled fiber optic system is also measured mathematically to satisfy the data transmission accuracy. For confirmation, the theoretical approach of the presented FSO and fiber optic network is realized with an aggregate 342 Gbps speed 16 × 22 . The performance metrics comprising forward error limit (FEL), bit error rate (BER), and error vector magnitude (EVM) are used for weighing simulation results. The outlets of an integrated fiber-FSO network show that by applying NR 5G sub-THz, a high data rate with multiple inputs and multiple outputs (MIMO) transmission capacity can be adjusted victoriously.
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Bhange, D. N., and C. Dethe. "A Novel LS/LMMSE Based PSO Approach for 3D-Channel Estimation in Rayleigh Fading." Advanced Electromagnetics 7, no. 4 (September 4, 2018): 117–23. http://dx.doi.org/10.7716/aem.v7i4.770.
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A high transmission rate can be obtained using Multi Input Multi Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) model. The most commonly used 3D-pilot aided channel estimation (PACE) techniques are Least Square (LS) and Least Minimum Mean Square (LMMSE) error. Both of the methods suffer from high mean square error and computational complexity. The LS is quite simple and LMMSE being superior in performance to LS providing low Bit Error Rate (BER) at high Signal to Noise ratio (SNR). Artificial Intelligence when combined with these two methods produces remarkable results by reducing the error between transmission and reception of data signal. The essence of LS and LMMSE is used priory to estimate the channel parameters. The bit error so obtained is compared and the least bit error value is fine-tuned using particle swarm optimization (PSO) to obtained better channel parameters and improved BER. The channel parameter corresponding to the low value of bit error rate obtained from LS/LMMSE is also used for particle initialization. Thus, the particles advance from the obtained channel parameters and are processed to find a better solution against the lowest bit error value obtained by LS/LMMSE. If the particles fail to do so, then the bit error value obtained by LS/LMMSE is finally considered. It has emerged from the simulated results that the performance of the proposed system is better than the LS/LMMSE estimations. The performance of OFDM systems using proposed technique can be observed from the imitation and relative results.
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Elgam, Avner, Yossi Peretz, and Yosef Pinhasi. "Analysis of OSTBC-OFDM Combined with Dual-Polarization and Time-Diversity in Millimeter-Wave MIMO Channels with Rain Distortions." Sensors 22, no. 19 (September 22, 2022): 7182. http://dx.doi.org/10.3390/s22197182.
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Various destructive weather and physical phenomena affect many parameters in the radio layer (i.e., affecting the wireless paths Over-The-Air (OTA)) of many outdoor-to-outdoor wireless systems. These destructive effects create polarization torsion and rotation of the signals propagating in space and cause the scattering of wireless spatial paths. The direct meaning is a significant degradation in system performance, especially in the Quality-of-Service (QoS). Under these challenging scenarios, intelligent utilization of advanced Multiple-Input-Multiple-Output (MIMO) techniques such as polarization-diversity and time-diversity at the transmitter, as well as at the receiver, and intelligent use of the Cross-Polarization-Isolation (XPI) mechanism, are essential. We prove that combining these techniques with the tuning of the XPI of the antennas creates optimal conditions in the wireless MIMO channels. This combination does not only improve the system’s performance, but also turns the destructive physical phenomena in the spatial-domain, into an advantage. In this article, we focus on formulating a wireless communication MIMO model in millimeter-Wave (mmWave) channels under rain distortions. We demonstrate the optimal use of combining Orthogonal-Space-Time-Coding (OSTBC) and Maximal-Ratio-Receive-Combiner (MRRC) with cross-polarization diversity techniques, that utilize the tuning of the XPI. An analytical exact optimal solution is proposed, that allows the tuning of the leading parameters to achieve global optimal performance, in terms of channel-capacity and Bit-Error-Rate (BER). In addition, we propose a process of approximation of feedback-closed-loop-MIMO. The feedback is employed between the transmitter and the receiver, in the scenario of changes in the channel-response-matrix in-between successive symbol-times. The feedback was designed to acheive global-maximum channel-capacity, while preserving the channel-path orthogonality in order to minimize the BER.
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Ibrahim, Isam Aameer, and Tahreer Safa's Mansour. "Design and Evaluation Study of Performance of Optical Wireless Sensors Network for Achieving High Data Rate and Power Saving." International Journal of Interactive Mobile Technologies (iJIM) 15, no. 14 (July 28, 2021): 38. http://dx.doi.org/10.3991/ijim.v15i14.21427.
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<p class="0abstract"><strong>Abstract—</strong>One of the major global issues today is the growing requirements for high-speed data transmission, energy consumption, and the huge volume of data utilized by a variety of multimedia applications such as video streaming, monitoring systems, and gaming. In this research, an analysis is carried out to study the design and evaluation of performance underwater OWC systems (UOWC) through medium communication link ranges to overcome absorption and scattering and to meet the requirements of a wide variety of optical wireless applications. Two modulation schemes of technology have been proposed in the UOWC system which is Differential Phase Shift Keying (DPSK) modulation with Direct Detection (DD) and the DPSK modulation with Coherent Detection (CD), both of them used Optical Orthogonal Frequency Division Multiplexing (OFDM) based on different configurations of multi-input multi-output technology (MIMO). The mathematical model has been proposed to calculate optimal beacon period (BI) and listen to the interval (LI) for preventing overlapping time between the signals and the required power is reduced. By using different types of water the simulation results are displayed the best performance of the UOWC system from link rang and receiver sensitivity. The simulation result of BER is equal 10<sup>-5</sup>, BI equal to 85ms, and LI equal to 108ms.</p>
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Alqaisei, Mohammed A., Abdel-Fattah A. Sheta, Ibrahim Elshafiey, and Majid Altamimi. "Design of Hybrid Beamforming System Based on Practical Circuit Parameter of 6-Bit Millimeter-Wave Phase Shifters." Micromachines 14, no. 4 (April 19, 2023): 875. http://dx.doi.org/10.3390/mi14040875.
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This paper addresses the design of a hybrid beamforming system considering the circuit parameter of six-bit millimeter-wave phase shifters based on the process design kit. The phase shifter design adopts 45 nm CMOS silicon on insulator (SOI) technology at 28-GHz. Various circuit topologies are utilized, and in particular, a design is presented based on switched LC components, connected in a cascode manner. The phase shifter configuration is connected in a cascading manner to get the 6-bit phase controls. Six different phase shifters are obtained, which are 180°, 90°, 45°, 22.5°, 11.25°, and 5.6°, with a minimum number of LC components. The circuit parameters of the designed phase shifters are then incorporated in a simulation model of hybrid beamforming for a multiuser MIMO system. The number of OFDM data symbols used in the simulation is ten for eight users, 16 QAM modulation schemes, −25 dB SNR, 120 simulation runs, and around 170 h runtime. Simulation results are obtained considering four and eight users, assuming accurate technology-based models of RFIC components of the phase shifter as well as ideal phase shifter parameters. The results indicate that the performance of the multiuser MIMO system is affected by the accuracy level of the phase shifter RF component models. The outcomes also reveal the performance tradeoff based on user data streams and the number of BS antennas. By optimizing the amount of parallel data streams per user, higher data transmission rates are achieved, while maintaining acceptable error vector magnitude (EVM) values. In addition, stochastic analysis is conducted to investigate the distribution of the RMS EVM. The outcomes show that the best fitting of RMS EVM distribution of the actual and ideal phase shifters agreed with the log-logistic and logistic distributions, respectively. The obtained (mean, variance) values of the actual phase shifters based on accurate library models are (46.997, 481.36), and for ideal components the values are (36.47, 10.44).
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Tran, Van Duy, Duc Khai Lam, and Thi Hong Tran. "Hardware-Based Architecture for DNN Wireless Communication Models." Sensors 23, no. 3 (January 23, 2023): 1302. http://dx.doi.org/10.3390/s23031302.
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Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO OFDM) is a key technology for wireless communication systems. However, because of the problem of a high peak-to-average power ratio (PAPR), OFDM symbols can be distorted at the MIMO OFDM transmitter. It degrades the signal detection and channel estimation performance at the MIMO OFDM receiver. In this paper, three deep neural network (DNN) models are proposed to solve the problem of non-linear distortions introduced by the power amplifier (PA) of the transmitters and replace the conventional digital signal processing (DSP) modules at the receivers in 2 × 2 MIMO OFDM and 4 × 4 MIMO OFDM systems. Proposed model type I uses the DNN model to de-map the signals at the receiver. Proposed model type II uses the DNN model to learn and filter out the channel noises at the receiver. Proposed model type III uses the DNN model to de-map and detect the signals at the receiver. All three model types attempt to solve the non-linear problem. The robust bit error rate (BER) performances of the proposed receivers are achieved through the software and hardware implementation results. In addition, we have also implemented appropriate hardware architectures for the proposed DNN models using special techniques, such as quantization and pipeline to check the feasibility in practice, which recent studies have not done. Our hardware architectures are successfully designed and implemented on the Virtex 7 vc709 FPGA board.
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Zhou, Zhou, Lingjia Liu, Vikram Chandrasekhar, Jianzhong Zhang, and Yang Yi. "Deep Reservoir Computing Meets 5G MIMO-OFDM Systems in Symbol Detection." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 01 (April 3, 2020): 1266–73. http://dx.doi.org/10.1609/aaai.v34i01.5481.
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Conventional reservoir computing (RC) is a shallow recurrent neural network (RNN) with fixed high dimensional hidden dynamics and one trainable output layer. It has the nice feature of requiring limited training which is critical for certain applications where training data is extremely limited and costly to obtain. In this paper, we consider two ways to extend the shallow architecture to deep RC to improve the performance without sacrificing the underlying benefit: (1) Extend the output layer to a three layer structure which promotes a joint time-frequency processing to neuron states; (2) Sequentially stack RCs to form a deep neural network. Using the new structure of the deep RC we redesign the physical layer receiver for multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) signals since MIMO-OFDM is a key enabling technology in the 5th generation (5G) cellular network. The combination of RNN dynamics and the time-frequency structure of MIMO-OFDM signals allows deep RC to handle miscellaneous interference in nonlinear MIMO-OFDM channels to achieve improved performance compared to existing techniques. Meanwhile, rather than deep feedforward neural networks which rely on a massive amount of training, our introduced deep RC framework can provide a decent generalization performance using the same amount of pilots as conventional model-based methods in 5G systems. Numerical experiments show that the deep RC based receiver can offer a faster learning convergence and effectively mitigate unknown non-linear radio frequency (RF) distortion yielding twenty percent gain in terms of bit error rate (BER) over the shallow RC structure.
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Safonova, Olga, Elena Arepyeva, and Nadezhda Ermakova. "Improved Efficiency of Data Transmission in Wireless Communication Systems with Orthogonal Frequency Multiplexing." NBI Technologies, no. 3 (December 2021): 15–18. http://dx.doi.org/10.15688/nbit.jvolsu.2021.3.3.
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The active introduction of Orthogonal Frequency Division Multiplexing (OFDM) technology is now beginning to be widely used in wireless transmission systems, television, radio communication, and radio broadcasting. The efficiency of using a dedicated frequency band at a constant high transmission rate allows you to combat interference arising from the transmission of a useful information on the radio channel. A method of improving quality of information transmission in communication systems with orthogonal frequency multiplexing is described. It is shown that with an increase in the number of receiving and transmitting antennas, the noise immunity increases significantly. An experiment was carried out to change the number of receiving-transmitting antennas and the signal-to-noise ratio, and the dependence of the appearance of an error on the number of transmitting antennas was obtained. The work investigated the software model of MIMO OFDM (modulators and demodulators). As a result of the analysis, the dependence of the appearance of the error frequency on the probability of the error was obtained. This showed that the use of OFDM and MIMO places increased demands on channel estimation.
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Hussein, Walaa, Kamil Audah, N. K. Noordin, Habib Kraiem, Aymen Flah, Mohd Fadlee, and Alyani Ismail. "Least Square Estimation-Based Different Fast Fading Channel Models in MIMO-OFDM Systems." International Transactions on Electrical Energy Systems 2023 (August 29, 2023): 1–23. http://dx.doi.org/10.1155/2023/5547634.
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In cellular wireless communication systems, channel estimation (CE) plays a pivotal role as a crucial technique applied in orthogonal frequency division multiplexing (OFDM) modulation. CE utilizes a variety of methods, including decision-directed channel estimation, pilot-assisted channel estimation (PACE), and blind channel estimation. Among these options, PACE is widely favored for its remarkable stability and consistent superior performance. The idea of massive multiple-input multiple-output (MIMO) shows tremendous potential for the future of wireless communications. However, existing massive MIMO systems face challenges with their high computational complexity and intricate spatial structures, preventing efficient utilization of channel and sparsity features in these multiantenna systems. In communication channels, the signal received is often influenced by the characteristics of the channel and noise present at the receiver. To address this issue, an efficient dataset is utilized, employing the least square (LS) algorithm for minimization. OFDM is a commonly and widely used modulation method in communication systems utilized to specifically combat resonance fading in wireless channels. In wireless communication systems employing OFDM-MIMO, frequency selectivity and time-varying attributes due to multipath channels cause Intercarrier Interference (ICI) among symbols. Channel estimation is a vital aspect for mitigating the effects of fading channels. This investigation focuses on the application of a method examined in the study, which involves a block-type pilot symbol-assisted estimation technique for Rayleigh and Rician fading channel models. The research assesses the performance of the least square (LS) channel estimators in fast-fading channel models while employing various symbol mapping techniques focusing on bit error rate, throughput, and mean square error. The results indicate that the LS estimator exhibits excellent performance in Rayleigh and AWGN channels within the pedestrian A (PedA) model for both uplink and downlink scenarios. It outperforms the PedA model without channel estimation.
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Rantelobo, Kalvein, Hendro Lami, and Wirawan Wirawan. "Video Transmission using Combined Scalability Video Coding over MIMO-OFDM Systems." Indonesian Journal of Electrical Engineering and Computer Science 4, no. 2 (November 1, 2016): 390. http://dx.doi.org/10.11591/ijeecs.v4.i2.pp390-396.
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<p><em>The needs of efficient bandwidth utilization and method to handle bandwidth fluctuation condition of wireless channel have become fundamental problems in video transmission. This research</em><em> proposed </em><em>Combined Scalable Video Coding (CSVC) that refers to Joint Scalable Video Model (JSVM), i.e. development of video coding H.264/AVC by exploiting scalable combination method using Medium Grain Scalability (MGS) on wireless channel of MIMO-OFDM (Multiple Input Multiple Output – Orthogonal Frequency Division Multiplexing) technology. Th</em><em>e</em><em> research shows that the scalable combination method can be implemented on the scenario for wireless transmission on multicast network. Experimental results show</em><em> </em><em>that the delivered quality is close to the alternative traditional simulcast delivery mechanism in MIMO-OFDM systems.</em></p>
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Ramljak, Ivana, Dinko Begušić, and Josip Lorincz. "Operational Characteristics of Square-Law Combining Energy Detector in MIMO-OFDM Cognitive Radio Systems." Applied Sciences 12, no. 9 (May 6, 2022): 4684. http://dx.doi.org/10.3390/app12094684.
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To ensure effective spectrum usage, cognitive radio networks (CRNs) are being investigated extensively. The important function of CRNs is spectrum sensing (SS). This is the process of sensing the unused frequency spectrum and deciding whether the signal transmission of a primary user (PU) exists. In this work, the results of a performance analysis related to detecting PU signals using the energy detection (ED) SS method realized by employing the square-law combining (SLC) technique are presented. The assessment of the effectiveness of the ED method is performed in relation to prominent communication technology based on Orthogonal Frequency Division Multiplexing (OFDM) and Multiple-Input Multiple-Output (MIMO) transmissions. Due to the impact of changes in the noise power of the PU signal, referred to as noise uncertainty (NU), the MIMO-OFDM transmission in a real communication environment cannot guarantee accurate sensing performed by employing ED based on the SLC method at the secondary user (SU). More precise SS can be achieved if dynamic detection threshold (DDT) changes are employed according to the channel conditions impacted by NU. Thus, this work investigated the effect of NU variations and DDT adjustments on the detection probability for various levels of false alarm probability. This interdependence is presented as receiver operating characteristic (ROC) curves. A mathematical model including different operational parameters was developed to define the fundamental parameters of the ED method based on the SLC approach. Using the developed mathematical model, an algorithm was created which simulates SLC ED processes using DDT in single-input single-output (SISO)- and MIMO-OFDM communication systems affected by NU. Based on the simulation results, comprehensive analyses of the impact of versatile DDT adaptations and NU variations on the shape of the ROC curves for the ED process performed with different numbers of transmitting and receiving antenna, modulation techniques, detection sample numbers, PU transmitting powers, and SNR values are presented.
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Cicerone, M., O. Simeone, and U. Spagnolini. "Channel Estimation for MIMO-OFDM Systems by Modal Analysis/Filtering." IEEE Transactions on Communications 54, no. 10 (October 2006): 1896. http://dx.doi.org/10.1109/tcomm.2006.881401.
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Cicerone, Marcello, Osvaldo Simeone, and Umberto Spagnolini. "Channel Estimation for MIMO-OFDM Systems by Modal Analysis/Filtering." IEEE Transactions on Communications 54, no. 11 (November 2006): 2062–74. http://dx.doi.org/10.1109/tcomm.2006.884849.
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Kim, Wonsop, Kyungnam Lee, Myung-Don Kim, Jae Joon Park, Hyun Kyu Chung, and Hyuckjae Lee. "Performance Analysis of Spatially Correlated MIMO-OFDM Beamforming Systems with the Maximum Eigenvalue Model from Measured MIMO Channels." IEEE Transactions on Wireless Communications 11, no. 10 (October 2012): 3744–53. http://dx.doi.org/10.1109/twc.2012.083012.120164.
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