Showing 7 results for Mimo
A. Merline, S. J. Thiruvengadam,
Volume 7, Issue 2 (6-2011)
Abstract
The role of waveform design is central to effective radar resource management for state-of-the art radar systems. The waveform shape employed by any radar system has always been a key factor in determining the performance and application. The design of radar waveform to minimize mean square error (MSE) in estimating the target impulse response is based on power allocation using waterfilling. This paper shows the effect of various power control strategies in the MMSE performance of the waveform design. We find that the truncated power control strategy exhibits a good MMSE performance. The performance improvement results from the fact that with the truncated power control no power is wasted in poor quality modes.
H. Khoshbin, S. M. Sajjadi,
Volume 8, Issue 4 (12-2012)
Abstract
Abstract: This paper proposes a novel scheme for multi-static passive radar processing, based on soft-input soft-output processing and Bayesian sparse estimation. In this scheme, each receiver estimates the probability of target presence based on its received signal and the prior information received from a central processor. The resulting posterior target probabilities are transmitted to the central processor, where they are combined, to be sent back to the receiver nodes or used for decision making. The performance of this iterative Bayesian algorithm comes close to the optimal multi-input multi-output (MIMO) radar joint processing, although its complexity and throughput are much less than MIMO radar. Also, this architecture provides a tradeoff between bandwidth and performance of the system. The Bayesian target detection algorithm utilized in the receivers is an iterative sparse estimation algorithm named Approximate Message Passing (AMP), adapted to SISO processing for passive radar. This algorithm is similar to the state of the art greedy sparse estimation algorithms, but its performance is asymptotically equivalent to the more complex l1-optimization. AMP is rewritten in this paper in a new form, which could be used with MMSE initial filtering with reduced computational complexity. Simulations show that if the proposed architecture and algorithm are used in conjunction with LMMSE initial estimation, results comparable to jointly processed basis pursuit denoising are achieved. Moreover, unlike CoSaMP, this algorithm does not rely on an initial estimate of the number of targets.
M. Rezaei, A. Falahati,
Volume 12, Issue 1 (3-2016)
Abstract
In this paper, a cooperative algorithm to improve the orthogonal space-timefrequency block codes (OSTFBC) in frequency selective channels for 2*1, 2*2, 4*1, 4*2 MIMO-OFDM systems, is presented. The algorithm of three node, a source node, a relay node and a destination node is formed, and is implemented in two stages. During the first stage, the destination and the relay antennas receive the symbols sent by the source antennas. The destination node and the relay node obtain the decision variables employing time-space-frequency decoding process by the received signals. During the second stage, the relay node transmits decision variables to the destination node. Due to the increasing diversity in the proposed algorithm, decision variables in the destination node are increased to improve system performance. The bit error rate of the proposed algorithm at high SNR is estimated by considering the BPSK modulation. The simulation results show that cooperative orthogonal space-time-frequency block coding, improves system performance and reduces the BER in a frequency selective channel.
H. Shayeghi, A. Younesi,
Volume 16, Issue 4 (12-2020)
Abstract
The main objective of this paper is to model and optimize the parallel and relatively complex FuzzyP+FuzzyI+FuzzyD (FP+FI+FD) controller for simultaneous control of the voltage and frequency of a micro-grid in the islanded mode. The FP+FI+FD controller has three parallel branches, each of which has a specific task. Finally, as its name suggests, the final output of the controller is derived from the algebraic summation of the outputs of these three branches. Combining the basic features of a simple PID controller with fuzzy logic that leads to an adaptive control mechanism, is an inherent characteristic of the FP+FI+FD controller. This paper attempts to determine the optimal control gains and Fuzzy membership functions of the FP+FI+FD controller using an improved Salp swarm algorithm (ISSA) to achieve its optimal dynamic response. The time-domain simulations are carried out in order to prove the superb dynamic response of the proposed FP+FI+FD controller compared to the PID control methods. In addition, a multi-input-multi-output (MIMO) stability analysis is performed to ensure the robust control characteristic of the proposed parallel fuzzy controller.
F. Asghariyehlou, J. Javidan,
Volume 18, Issue 2 (6-2022)
Abstract
This paper deals with the optimization of the CORDIC-based modified Gram-Schmidt (MGS) algorithm for QR decomposition (QRD) and presents a scalable algorithm with maximum throughput, the least possible latency, and hardware resources. The optimized algorithm is implemented on Xilinx Virtex 6 FPGA using ISE software as a fixed point with selected accuracy based on the results of MATLAB simulation. Using the loop unrolling technique with different coefficients, an attempt is made to reduce the latency and increase the throughput. In contrast, increasing the unrolling factor leads to a decrease in the frequency of the CORDIC unit as well as a decrease in the number of resources. As a result, there is a trade-off between the unrolling factor and the frequency of the CORDIC unit. By investigating the different unrolling factors, it is shown that the loop unrolling technique with a factor of 4 has the highest throughput with the value of 5.777 MQRD/s and the lowest latency with the value of 173 ns. Moreover, it is shown that throughput and latency are improved by 42.52% and 73.74% respectively compared to the not optimized case. The proposed method is also scalable for different sizes of m×m complex channel matrices, where log2 m ∈ N.
Smita Jolania, Ravi Sindal,
Volume 20, Issue 1 (3-2024)
Abstract
Fifth Generation-New Radio (5G-NR) is an advanced air interface defined to fulfil diverse services with ubiquitous coverage in next generation Wireless networks. The waveform is the crucial part of air interface that must have good spectral confinement and low peak-to-average power ratio (PAPR). Orthogonal Frequency Division Multiplexing (OFDM) is a widely used air interface in Fourth Generation Long Term Evolution (4G-LTE) system. But OFDM suffers from high PAPR, Carrier Frequency offset (CFO), and loss of spectral efficiency due to insertion of cyclic prefix. So, the high dense networks with heterogeneous traffic in the 5G requires new multicarrier waveform. In the proposed work, waveforms based on sub-band filtering are considered due to more flexibility and shorter filter length as compared to the sub-carrier-based filtering waveforms. Two major 5G waveform candidates Filtered-Orthogonal Frequency Division Multiplexing (F-OFDM) and Universal Frequency Division Multiplexing (UFMC) are proposed in the system design. Channel coding is the inherent part of air interface for enhancing the error performance. New error correcting channel codes introduced in NR to support variable information block length and flexible codeword size. The capacity achieving Polar codes is the highlight of this paper adopted for control channels. 5G NR air interface using new modulation waveform along with the polar coding can be an effective way to enhance error performance. This paper presents comparative analysis of comprehensive systems Polar coded F-OFDM (PC-F-OFDM) and Polar coded UFMC (PC-UFMC) in massive MIMO scenario. Simulation results indicate that the proposed PC-F-OFDM systems significantly outperform the PC-UFMC systems in AWGN channel. But in massive MIMO setup BER performance of PC-UFMC is better than PC-F-OFDM system.
Shivanand Konade, Manoj Dongre,
Volume 20, Issue 2 (6-2024)
Abstract
The proposed research presents a two-port compact Multiple Input Multiple Output (MIMO) antenna for Ultra-Wide Band (UWB) applications. The designed antenna has two identical radiators and has an overall dimension of 20 × 44.1 × 1.6mm3 on a FR4 substrate. The designed antenna is fed by a 50-microstrip line. Extended F-shaped stubs are introduced in the shared ground plane of the proposed antenna to produce high isolation between the MIMO antenna elements. Extended F-shaped stubs are introduced in the ground plane to produce multiple resonance and high isolation between the radiating elements. The antenna offers good impedance matching in the UWB band. The proposed antenna has lower isolation < -25 dB and Envelope Correlation Coefficient (ECC) < 0.015 from 3.1 to 10.6 GHz. Antenna parameters are evaluated in term of return loss, ECC, Diversity Gain (DG), gain, Total active reflection coefficient (TRAC) radiation pattern and isolation. The proposed antenna is tested and fabricated. However, obtained results are good agreement which make suitable for UWB wearable applications.
