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In order to solve the problem of frequency-hopping signal detection, an improved algorithm based on power spectrum elimination and pulse detection is proposed. Firstly, judge the signal type and estimate the width of signal with the hopping frequency by STFT and pulse detection. Then, eliminate the frequency-fixed signal interfere by suppressing the signal. Finally, judge the threshold to realize...
Recentry, interference of artificial noises from electrical power transfer becomes large and deterioration of sound quality of AM radio is worried. The authors proposed a noise suppression system for AM radio using quadrature demodulation and PI algorithm. It is expected that the noise suppression effect is reduced when the system has a synchronization error. In this paper, an effect of synchronization...
Bit error rate(BER) analysis of an L antenna equal gain combiner (EGC) in correlated composite fading channels and in independent and identically distributed (i.i.d) non-homogenous fading channels is evaluated in the presence of co-channel interference(CCI) and imperfect estimation of carrier phase. The nth moment of the combiner output signal to interference plus noise ratio(SINR) is derived individually...
Since it is challenging to position the noncooperative receiver (Rx), especially when the backward frequency band of the Rx cannot be obtained by the anchors. In this paper, we propose a novel noncooperative Rx positioning method using full-duplex relay technique, where the anchors act as full-duplex relays for the Rx. It can trigger the close-loop-power-control (CLPC) between the transmitter (Tx)...
In the future millimeter-wave small-cell communication systems, relay cooperation is deemed as one of the promising techniques to realize green communication. In relay cooperative system, the selected relaying mode determines the system performance in some extent. For the commonly used modes, amplify-and-forward (AF) and decode-and-forward (DF), which one should be taken in specific scenario? In this...
Energy-efficient design has emerged as a promising technique in heterogeneous networks. We study the energy efficiency problem of joint user association and power allocation in a two-tier heterogeneous network with small cells. The energy efficiency is maximized under certain prescribed quality-of-service requirement and maximum power limit constraint. The original optimization problem is a nonconvex...
In this paper, the security of multi-input single- output (MISO) amplify-and-forward relaying network with untrustworthy relay nodes is considered, where the untrustworthy nodes can help to forward the received signal and they may also try to decode such information, which can be regarded as potential eavesdroppers (Eves). To deal with such kind of smarter Eves, relay selection is adopted and both...
The study of secrecy capacity of wireless networks, considering variety of powerful attacks is currently of great interest. In this paper, we have considered a possible attack scenario where an eavesdropper is present as a legitimate relay node in disguise in the network. A novel scheme of simultaneous transmission of jamming signal and message signal is proposed to confuse the eavesdropper. Here...
This paper analyses the impact on the error vector magnitude (EVM) of the received carrier aggregated orthogonal frequency division multiplexing (OFDM) signal when it is passed through a nonlinear high power amplifier (HPA). This analysis will help to measure the quality of transceivers in modern communication systems, which are highly sensitive to nonlinear distortions caused by HPA. Specifically,...
A two-stage downlink beamforming design is proposed for multicell multi-input single-output channels with limited backhaul capacity and local channel state information (CSI). The first stage is to maximize the signal-to-leakage-plus-noise ratio with local CSI. Each base station (BS) then calculates the corresponding channel gains and shares them with all other BSs, which typically requires low-rate...
Differential encoded LDPC (DE-LDPC) coded systems with multiple symbol differential detection (MSDD) scheme can avoid good estimation of channel state information and compensate performance degradation of differential detection. In this paper, LDPC codes optimization for the DE-LDPC coded systems with MSDD is studied. Simulation results show that the optimized LDPC codes perform much better than the...
In this paper, an energy efficient power allocation approach for amplify-and-forward relay networks is proposed. The proposed method aims to maximize the power normalized signal-to-noise ratio (PN-SNR) while satisfying the constraints of total and individual relay transmit powers. The resultant optimization problem can be solved using Karush-Kuhn-Tucker (KKT) optimality conditions. The proposed method...
In this paper, we study the secrecy outage probability (SOP) of an opportunistic relay selection scheme where an optimal relay is selected based on the delayed feedback from the multi-antenna destination. We present a new exact closed-form expression of the SOP, and two kinds of asymptotic form of SOP are further derived to explicitly show secrecy performance. In addition, we show that the SOP can...
A current mode background light subtraction circuit is presented for time-of-flight based 3D cameras. The circuit is implemented in current mode to overcome the requirement of large size MIM capacitors in voltage domain. The current based subtraction also increases the camera speed due to reduction of two integration cycles as compared to voltage mode circuits. A current integrator circuit is used...
The orthogonality principle states that as an adaptive filter approaches to the Weiner solution and error approaches to its minimum value, the correlation between error and input signal approaches to zero. This fact has been exploited in the proposed scheme for the minimizing mean square deviation (MSD) for the tap weights and its estimated value at each iteration. Essentially, this paper proposes...
In this paper, we propose a sensing nodes selection scheme to achieve energy efficiency in cooperative spectrum sensing for cognitive sensor networks. In cooperative spectrum sensing, nodes send their results to a fusion center (FC) to make the final decision using a fusion rule. While minimize the energy consumption, we also consider improving the detection performance in our approach by maximizing...
Forward error control (FEC) codes based on turbo, low-density parity-check (LDPC) and polar principles provide practical approaches towards channel capacity. There are, however, remaining challenges. Some of these are listed below.
In this paper, we introduce an optimal beamformer design that facilitates a compromise between high directivity and low white noise amplification. The proposed beamformer involves a regularization factor, whose optimal value is determined using a simple and efficient one dimensional search algorithm. Simulation results demonstrate controlled tuning of various gain properties of the desired beamformer,...
In this paper, we analyze the performance of a cooperative cognitive radio network when secondary users (SUs) are operating in different environments. The variable operating conditions result in variable SNRs at each SU. Besides, closed forms of detection and false alarm probabilities are computed assuming that cognitive terminals are performing spectrum sensing using energy detection technique. Simulation...
In this paper, the secrecy of a cooperative system consisting of a single source, relay, destination and eavesdropper is analyzed. The threshold-selection decode-and-forward relay is considered, where the relay can correctly decode and forward only if it satisfies a threshold signal-to-noise ratio (SNR). Both destination and eavesdropper take advantage of the direct and relayed transmissions through...
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