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In this paper, the power allocation problem for Orthogonal frequency division multiplexing(OFDM)-based relay cognitive radio systems is investigated. An optimization power allocation algorithm is developed. In the algorithm, objective function is studied and simplified. The channel capacity of secondary users is maximized while keeping the total interference introduced to primary user less than a...
In this paper, a channel estimation (CE) and precoding scheme by using H-infinity (H-inf) criterion for mitigation of pilot contamination (PC) in Massive multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems is reconsidered. Firstly, different thresholds in H-inf CE and precoding are considered. Secondly, asymptotic analysis of the large system is applied...
This paper focuses on the optimal waveform design for target detection in scenario of range-spread target. The previously published papers, which focused on optimal waveform design, assumed the target impulse response is perfect or known. However, the target impulse response used for next transmitted waveform is the previous target impulse response. The transmitted waveform designed should aim to...
In this paper, a suboptimal subcarrier and power allocation algorithm has been developed for the orthogonal frequency division multiplexing(OFDM)-based relay cognitive radio systems. The channel capacity of secondary users is maximized while keeping the total interference introduced to primary user less than a given threshold with a specified power. Compared with the other power allocation algorithm,...
The constant modulus algorithm (CMA) has been known as blind adaptive beamforming because it requires no knowledge about the signal except that the transmitted signal waveform has a constant envelope. But in practical applications, the performance of the linearly constrained CMA is known to degrade severely in the presence of even slight signal steering vector mismatches. To account for the mismatches,...
A novel robust least squares constant modulus algorithm (LSCMA) is proposed for blind adaptive beamforming, which is based on explicit modeling of uncertainty in the desired signal array. To improve robustness, the weight vector is optimized to involve minimization of cost function, while imposing the oblique projection constraint on the weight vector and maintaining a distortionless response for...
The conventional constrained least squares constant modulus algorithm (LSCMA) can suffer significant performance degradation in the presence of the slight mismatches between the actual and assumed signal steering vectors. In this paper, to combat the mismatches, a novel robust constrained LSCMA is proposed for implementing double constraints with Taylor-series expansion and Lagrange multipliers method,...
In practical applications, mismatches between assumed and actual array responses lead to serious degradation of SINR at the array output. In this paper, we propose robust CMA based on the quadratic constraint, which improves the output performance. The quadratic constraint on the weight can provide excellent robustness to signal steering vector mismatches and to random perturbations in sensor parameters...
In practical problems, the constrained least square constant modulus algorithm (LSCMA) can suffer significant performance degradation in the presence of the slight mismatches between the actual and presumed array responses to the desired signal. In this paper, a novel robust constrained LSCMA is proposed based on explicit modeling of uncertainties in the desired signal array response. The proposed...
The adaptive beamforming algorithm can aim at the direction-of-arrival of jammer automatically. But when the antenna platform vibrates or interference moves quickly, it is possible that the mismatching occurs between adaptive weight and data due to the perturbation of the interference location. To solve these problems above, a new robust beamforming control method is presented to widen nulls of adaptive...
When adaptive arrays are applied to practical problems, the constrained LSCMA can suffer significant performance degradation in the presence of the mismatch between the actual direction of arrival (DOA) of the signal and the look direction of the beamformers. In this paper, a novel robust constrained LSCMA under signal steering vector mismatches is proposed by using a Bayesian approach, which is robust...
When the array steering vector is precisely known, adaptive beamforming is known to have resolution and interference rejection capability. However, the performance of adaptive beamforming techniques may degrade severely in the presence of mismatches between the assumed array response and the true array response. Similar types of degradation can occur when the signal array response is known exactly,...
When applying adaptive arrays to actualities, the performance of existing adaptive array algorithms is known to degrade substantially because of the slight mismatch between actual and presumed array responses to the desired signal. In this paper, a novel robust adaptive beamforming algorithm under directional uncertainty is therefore proposed using a Bayesian approach to respond to the current environment...
Adaptive beamforming is known to have resolution and interference rejection capability when the array steering vector is precisely known. However, the performance of adaptive beamforming techniques may degrade severely in the presence of mismatches between the assumed array response and the true array response. In this paper, we propose a novel neural network approach to robust adaptive beamforming...
We present a new receiver structure able to deliver high data rates in a multi-input-multi-output (MIMO) frequency selective wireless environment. The parallel interference cancellation MIMO decision feedback equalization based on recursive least square algorithm (RLS-PIC-DFE) is obtained by canceling decided symbols from the received symbols parallel with the decision feed-forward equalizer (DFE)...
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