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This paper reports on a novel method that analyses signals' Mth power spectrum to classify the modulation type of MPSK signals without carrier and symbol synchronization. Whether signals through the filter or not makes no difference to this method and the multi-path effect has less influence on it. Simulations show that the correct recognition rate up to 99% for SNR >-1 dB.
This paper introduces eigen-beamforming technique into the STBC multiplexing scheme. STBC multiplexing scheme integrates orthogonal space time block codes into spatial multilayers such as V-BLAST structure. This hybrid system can balance the spatial multiplexing and diversity gain efficiently. When perfect channel state information (CSI) is available at the transmitter, eigen-beamforming can be employed...
In this paper, we proposed an efficient joint sub-carrier, bit and power allocation algorithm which tries to minimize the total transmit power for OFDM system, while maintaining the BER constraint and the rate requirement of each user. Some existing allocation algorithms allocate resources based on the "best channel gain" rule, which made some resources assigned to the users which are in...
Because most practical communication systems need possessing higher bandwidth efficiency, this article increases the bandwidth efficiency through the two aspects of code rate and modulation mode, that is, by combining CTC(convolutional turbo code) in WiMax protocol with MSK modulation and applying them in the practical communication systems. The simulation result shows the combination of CTC and MSK...
The concept of cooperative diversity promises to offer the benefits of spatial diversity gains to handheld wireless devices with single antennas. So far the research has focused on special modulation or space-time coding in order to allow the cooperating terminals transmit simultaneously during the relay phase. In this paper, we proposed a joint relay selection and ARQ scheme in the cooperative diversity...
A novel classification method for 2FSK and bi-signal is proposed in this paper. The bi-signal is two signals which appear at the same time. In words, they are mixed on time domain. The spectrum of both 2FSK and bi-signal has two peaks. So it is difficult to classify whether the two spectrum peaks is from 2FSK or bi-signal. Using short time Fourier transform, we devise a method that can recognize 2FSK...
Considering ultra wide band (UWB) system which transmits data information using ultra-short pulses, a pulse shape modulation UWB system based on orthogonal UWB pulse is proposed, which is on the basis of the orthogonality and non- direct component of modified Hermite polynomial function. The simulation result shows that the method can not only improve the performance, but also decrease the bit error...
In this paper, a novel quasi-4PPM modulation is presented firstly for UWB systems, and then the corresponding synchronization and demodulation schemes are proposed. Due to the nature of the unique signal structure, the information bits are transmitted and demodulated by twos, which doubles the transmission efficiency compared with conventional existing methods under the same condition. Besides, the...
An exact method is employed to analyze the bit error rate (BER) performances of differential chaos shift keying (DCSK) communication system over fading channels. The exact BER performances of DCSK in Nakagami-m, Rayleigh and Rician fading channels are derived, respectively. The Gaussian approximation (GA) method is compared with the exact method. The numerical and simulation results for the two methods...
Because noise subspace estimation for blind channel estimation can't achieve a good trade-off between convergence speed and steady-state error, and an ambiguous complex coefficient exists between estimated and actual channel impulse response. In this paper, we propose a blind channel estimation algorithm based on noise subspace estimation algorithm with adaptive variable step-size and ambiguous complex...
In this paper, a novel automatic modulation recognition method is proposed based on unsupervised learning neural networks, which adopts self-organizing map (SOM) algorithm. Firstly the basic structure of the SOM neural networks is described, and then the traditional training algorithm of SOM is improved in terms of learning efficiency and classification performance. Practical communication signal...
Differential turbo coded OFDM(DTC-OFDM) scheme was presented, together with a differential soft-detection method for Ka-band satellite communications. DTC-OFDM combines Turbo codes, orthogonal frequency division multiplexing (OFDM) modulation and differential detection, which has the advantages of high spectrum efficiency and suppression of multipath fading, jamming and noise. The DTC-OFDM system...
Although UNB is scorned by the advanced in the art, a new view of understanding it is presented through power spectra and bandwidth analysis. Bandwidths of UNB modulation schemes such as VMSK are analyzed by deducing their power spectrum analytical forms. Both mathematical analysis and simulation results show that UNB modulation schemes cannot attain high bandwidth efficiency. A conclusion is reached...
In this paper eigen-beamforming and differential space-time modulation (DSTM) are combined together to construct a robust and relatively simple system for multiple-input multiple-output (MIMO) Ricean fading channels. A transmission scheme with feedback link is developed here that combines beamforming with differential multi-antenna modulation based on orthogonal space-time block coding. The power...
A differential space-time modulation transmission scheme with adaptive transmit eigen-beamforming and power loading is developed exploiting the correlation of the channels at the transmitter. Based on the analysis of the error probability of spatially correlated Rayleigh fading channels, adaptive transmit eigen-beamforming and power loading are carried out according to the change of channels and the...
This paper addresses the problem of automatic modulation recognition of digital signals. A classification method based on spectral correlation and Support Vector Machine (SVM) is developed. The spectral correlation theory is introduced and several characteristic parameters which can be used for modulation analysis are extracted. The parameters are used as the input feature vectors to SVM. SVM maps...
A general digital modulation recognition method is proposed for common M-ary digital modulations. A coarse recognition is executed, then different algorithms are used to estimate the order of modulation. The estimation method of the number of spectrum peaks is modified and a novel recognition algorithm of modulation order of MASK and MQAM is presented. Simulations results show that the recognition...
In this paper, a novel forward link cooperation scheme using hierarchical modulation is proposed. We define a cooperative unit cell as a unit which includes base-station (BS), fixed relay-station (FRS) and two types of mobile-station (MS) being the relay-assisted mobile-station (RAMS) and the non-relay-assisted mobile-station (NRAMS). We describe how to exploit the hierarchical modulation for the...
User cooperation provides transmit diversity even when mobile users cannot possess multiple antennas due to size constraints. Recently, a kind of user cooperation scheme called coded cooperation was proposed, in which standard channel coding methods were used to implement cooperation. This scheme achieves remarkable gains compared to non-cooperative system and other cooperation diversity scheme (such...
This paper proposes novel higher-order statistic amplitude features in high-order cyclic cumulant domains. More classification information is preserved to adapt to more modulation types. Three representative feature sets extracted from time/frequency, high-order cumulant and high-order cyclic cumulant domains. The combined feature sets could make full use of the information and advantage of the three...
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