Performance Analysis of a Novel Cooperative Diversity Scheme

The traditional cooperative diversity could improve the system performance enormously, which has already widely been investigated by researchers. How-ever, it didn＇t exploit channel code and Distributed space-time block code （DSTBC） together to achieve both diversity gain and coding gain. Therefore, in order to further improve system performance, a novel cooperative diver-sity scheme based on concatenating the channel code and DSTBC is proposed in this paper. The closed-form expres-sions of channel capacity, outage probability and Bit error rate （BER） are derived to evaluate the performance of the proposed scheme. Also, computer simulations are conducted to validate our scheme, showing that, even though the interuser channel is noisy, the proposed scheme out-performs the traditional cooperative diversity in terms of channel capacity, outage probability and BER with distinct system gains.     

The Optimization of Combined Beamforming with Space-Time Block Coding

The combination of beamforming and Alamouti space-time block coding may not be optimal in rich scattering since it only uses two equal energy loading beams. A new scheme combining beamforming with spacetime block coding is put forward in this paper. The new scheme requires only the knowledge of channel correlation at the transmitter, the optimization design turns out to be an eigen-beamformer with multiple beams pointing to orthogonal directions along the eigenvectors of the channel correlation matrix and combine with appropriate spacetime block coding. In order to minimize a tight upper bound on the symbol error rate the optimal energy loading algorithm is proposed in this paper. We assume that the channel receive vectors observed on different receive antennas are mutually uncorrelated, but have the same correlation matrix, thus the new scheme can be extended to multiple receivers. The combination of beamforming and Alamouti space-time block coding is a special case of the new scheme. Based on Laplace transform, this paper provides an algorithm to calculate the probability density function of the equivalent signal to noise ratio, thus the closedorm expressions for the symbol error rate of the new scheme are derived. Simulation results demonstrate the superiority of the new scheme.     

？hrough-Wall Tracking of Human Movers Using Continuous-Wave Radar

An intelligent frequency fitting algorithm is presented for continuous-wave radar to track human movers through walls. With the proper fitting dimension, which is usually determined by the practical detection re- quirements, this technique can improve the localization ac- curacy and the tracking performance without introducing too much calculation burden, and more precisely identify different targets even in the frequency ambiguous areas. This technology can also help to match the estimation re- sults to their corresponding targets automatically, which is of great importance to certain urban sensing applications, such as specific target surveillance and tracking. To further improve the detection performance and better identify the weak targets in the presence of strong noise, CLEAN al- gorithm and adaptive filter technology are also involved. Experimental results are provided to illustrate the algo- rithm performance.     

Channel Mismatches Correction in Time-Interleaved ADCs Based on Hybrid Filter Bank Reconstruction

Time-interleaved analog-to-digital con- verter （TIADC） is an efficient way to achieve higher sam- pling rate for medium-to-high resolution applications. The performance of a TIADC suffers from the mismatch errors among the sub-channels. This paper presents a method to estimate the channel mismatches using the sub-channels output data. The proposed method introduces an equiv- alent transfer function for each channel to model and es- timate the mismatch errors. A Hybrid filter bank （HFB） structure is used to both model the TIADC and recon- struct the desired uniformly sampled sequence based on the perfect reconstruction conditions of the HFB system. A four-channel 12-bit 400MHz TIADC has been imple- mented in hardware to verify the proposed calibration method. The measured results show that the Spurious- free dynamic range （SFDR） can be improved up to 74dB after being corrected with 64-tap Finite-impulse response （FIR） filters.     

Spaceborne/Airborne Hybrid Bistatic SAR Frequency Domain Imaging Processing Algorithm

An imaging algorithm mainly processed in the frequency domain for the hybrid spaceborne/airborne BSAR is presented. The key point of deriving the algo- rithm is the analytical evaluation of the system transfer function＇s 2-D spectrum. To overcome the difficulty of resolving analytical solution for the stationary phase point, the spectrum＇s phase is approximated by two-order Taylor expanding around the point, which is in the neighborhood of the system＇s corresponding stationary phase point and can be obtained analytically. Thus the approximated analytical spectrum is pretty close to the actual one. In the imaging algorithm, both range-dependent range cell migration and azimuth-dependent range cell migration are compensated in two steps： Scaled inverse Fourier trans- form （SIFT）, which can be realized through the chirp z-transform, and phase multiplication. The validity of the algorithm is demonstrated by simulation with both the point target and area target.     

An Improved Cochlear Implant Strategy Incorporating Frequency Modulation Information

Some currently popular strategies in Cochlear implants （CIs） fail to encode the temporal fine structure cues, which are crucial for speech perception in noise or melody appreciation of CI patients. We propose an improved strategy based on the CIS （Continuous interleaved sampling） model by introducing partial lowfrequency temporal fine structure cues or Frequency modulation （FM） information into the slowly varying temporal envelops. A psychoacoustic experiment was conducted to validate the improved strategy by measuring the Mandarin vowel, tone, consonant and sentence recognitions on normal hearing listeners. Experimental data show that the introduction of frequency modulation information can improve the CI performance greatly, especially for vowel and tone perception. Firstly even at the most severe noise condition the vowel perception can get nearly half intelligibility, and the tone recognition scores increased over 20% at various noise conditions. Secondly under moderate noise conditions or in quiet the fine structure cues also contribute significantly to the consonant and sentence recognitions. Finally, the proposed strategy has its own application values because it does not introduce too many high-frequency components into the model, which can not be perceived by deaf patients. .     

A Novel Surface Treatment Method for Improving the Antenna System Performance of Mobile Phones with Stainless Steel Frame

A novel surface treatment method of plat-ing Cu＋PPS film/coating on a mobile phone＇s stainless steel frame for improving the antenna system efficiencies is proposed. The mobile phone was measured in free space, in a silicon cover, and in the hand and cover si- multaneously. It＇s found that with this surface treat-ment, the total efficiency of the antenna system can be improved in all the four cases respectively by 14.22%, 1.38%, 15.19% and 1.72% at 940MHz （GSM900：880- 960MHz）, 2.59%, 3.21%, 4.81% and 1.43% at 1720MHz （DCS：1710-1880MHz） and 6.34%, 2.85%, 9.83% and 2.32% at 2100 MHz （WCDMA：1920-2170MHz）. This low- cost surface treatment method is an important break- through to improve antenna system performance of mobile phones especially for those with a stainless steel frame, and suitable for mass production.     

Quantized Phase Step Technique Based on Different Frequency Signals and Its Characteristics

Through theoretical analysis and experiments, we discovered the quantized phase step technique existing in two cyclical movements, and the variation law of phase difference between two different frequency signals. This discovery is a major breakthrough in the traditional phase processing for researching frequency signals or cyclical movements that widely exist in nature. It has realized direct phase comparison between any signals without frequency normalization. Experimental results show that the resolution with femtosecond （fs） can be easily achieved in frequency measurement, frequency standard comparison and control on the basis of the quantized phase step characteristics. This important discovery can be widely used in navigation positioning, space technique, communication, radar, astronomy, atomic frequency standard and so on.     

Face Feature Selection and Recognition Using Separability Criterion and Binary Particle Swarm Optimization Algorithm

Discrete cosine transform （DCT） is an ef- fective method to extract proper features for face recog- nition. Discrete cosine transform can only map the re- source data to another data field instead of compress data. How to select the DCT coefficients that are most effec- tive for classification is an important problem. This paper proposes a novel method to search the best discriminant combination of DCT coefficients. A feature selection al- gorithm according to the separability criterion is used to preselect the DCT coefficients, and then follows a search algorithm based on binary particle swarm optimization and support vector machine to find an optimal combination of the DCT coefficient. The performance of the algorithm is assessed by computing the recognition rate and the num- ber of selected features on ORL database and Cropped Yale database.     

The Euclidean Distance Spectra of FDMA-CPM： Algorithms and Applications

The performance of multiuser Continuous phase modulation（CPM） over the additive white Gaussian noise channel with coherent maximum likelihood detection is considered. Algorithms are developed to calculate the Euclidean distance spectra employing tree-search and Astar algorithm. The complexity of proposed algorithms are further reduced using trellis minimization. The distance spectrum is then used to evaluate the performance of mul- tiuser CPM systems, which reveals that the performance of multiuser CPM can be significantly improved by using op- timized parameters. Both equally-powered and non-equally powered systems are considered. Numerical and simulated results confirm that the proposed algorithms can generate the distance spectra of all systems with lower complexity relative to previous methods and are particularly suited for multi user CPM systems.     

Directional Beamforming for High-Speed Railway Communications with Frequency Offset Precorrection

This paper considers a multi-antenna transmission strategy for high speed railway communica- tions. In order to achieve better performance than conven- tional space-frequency block coding schemes, we propose a directional beamforming strategy for the High-speed rail- way （HSR） communication by exploiting some characteris- tic of the railway system including predetermined moving tracks and real-time positioning information. Moreover, for alleviating the effect of Doppler shift due to the moving train, a frequency offset precorrection method is also incor- porated with direction beamforming. Theoretical Signal- to-noise ratio （SNR） gain of the proposed beamforming scheme over traditional HSR communication schemes is also derived for illustrating the performance enhancement. Numerical results verify the effectiveness of our proposed scheme even with some kind of imperfect position infor- mation available at the transmitter.     

Incomplete Fingerprint Recognition Based on Inproved GA-PSO

Minutiae-based algorithm plays a more and more important role in fingerprint recognition. It is greatly limited by its demand for good image quality and depen- dence on fingerprint aligning, especially for incomplete fin- gerprint recognition. Improved Genetic algorithm-Particle swarm optimization （GA-PSO） algorithm is applied to deal with these problems. The proposed algorithm improves GA-PSO in two aspects, population initialization based on reference point pre-aligning and fitness function construc- tion based on fusion of minutiae-matching and orientation- matching. The experimental results on the FVC2004 show the high effectiveness and practicability of our algorithm.     

NIR Chemical-Image Analysis Based on Adaptive Local Optimization PSO

Principal component analysis （PCA） com- bined with cluster analysis has become an effective ap- proach for Near-infrared （NIR） chemical image analysis. Traditional cluster algorithms are sensitive to initial start- ing conditions and can be trapped into local optimal so- lutions. To overcome the drawbacks, we develop a new algorithm in this paper which improves Particle swarm op- timization with Adaptive local optimization （ALO-PSO）. Simulation experiments performed on NIR image of tablet verify the feasibility and effectiveness of the proposed algo- rithm. Experimental results of the clustering performances indicate that ALO-PSO algorithm offers an alternative ap- proach for solving data clustering problems in NIR chem- ical image analysis.     

DOA and Power Estimation Using Genetic Algorithm and Fuzzy Discrete Particle Swarm Optimization

Aiming to reduce the computational costs and converge to global optimum, a novel method is proposed to solve the optimization of a cost function in the estimation of direction of arrival(DOA). In this method, a genetic algorithm(GA) and fuzzy discrete particle swarm optimization(FDPSO) are applied to optimize the direction of arrival and power parameters of the mode simultaneously. Firstly, the GA algorithm is applied to make the solution fall into the global searching. Secondly, the FDPSO method is utilized to narrow down the search field. In FDPSO, a chaotic factor and a crossover method are added to speed up the convergence. This approach has been demonstrated through some computational simulations. It is shown that the proposed algorithm can estimate both the DOA and the powers accurately. It is more efficient than some present methods, such as the Newton-like algorithm, Akaike information critical(AIC), particle swarm optimization(PSO), and genetic algorithm with particle swarm optimization(GA-PSO).     

一种LTE多小区干扰环境下的信道估计方法

随着无线通信的发展,小区密度与频谱利用率不断增加,高频率复用度使得处于小区边缘的用户受到严重的来自邻小区的同频干扰。提出一种长期演进(LTE)多小区干扰环境下的信道估计算法,当服务小区与强干扰小区使用相同的导频位置,且两小区之间存在时偏与频偏时,联合估计服务小区与干扰小区的信道频域响应(CFR);根据导频位置、导频序列、时偏和频偏大小信息建模,通过求解方程组得到服务小区与强干扰小区的信道时域响应(CTR),对服务小区与强干扰小区CTR分别进行傅里叶变换得到CFR。仿真结果表明,在服务小区信干噪比(SINR)较小时,与传统信道估计算法相比,所提方法在归一化均方误差(NMSE)、误比特率(BER)性能上均有明显提升。     

New SMMW laser transitions optically pumped by a tunable CO2waveguide laser

Optical pumping of a submillimeter wave (SMMW) laser with a relatively compact RF-excited CW CO2laser is described. The increased frequency tunability of the waveguide pump laser has resulted in new low threshold SMMW emissions in C2H2F2, CDF3, and CD2F2by pumping into absorption lines which are beyond the tuning range of a conventional CO2laser. Frequency offsets and some assignments obtained with the aid of a tunable diode laser heterodyne spectrometer are reported.     

Blind self-noise-free frequency detectors for a subclass ofMSK-type signals

Frequency offset due to Doppler shift and/or oscillator instabilities degrade the receiver performance. A family of frequency detectors for frequency offset estimation and compensation in digital receivers is introduced. The proposed detectors are best suited for frequency offset compensation of a subclass of binary continuous phase modulation with h=1/2 that includes modulation schemes with nonnegative frequency pulses. For the considered modulation schemes, the modulation-induced self-noise term is absent from the variance of the frequency estimate. The estimator is nondata- and nontiming-aided and its estimation range is either half or a quarter of the bit rate (R). With larger frequency offsets, the estimators that have a ±R/2 estimation range introduce a frequency ambiguity of R that is of no relevance to the performance of a differential detection based receiver     

WCDMA中FDD模式下的RNC-Iub/Iur接口同步方案

本文探讨了WCDMA中频分双工（FDD）模式下的RNC-Iub/Iur接口同步技术,阐述了“RNC-Node B”节点同步的概念,实现过程及其应用,讨论了连接帧编号（CFN）的定制技术,提出了CFN的获得方法。此外,还介绍了传输信道同步和接收窗的概念,讨论了传输信道同步的实现过程,并提出了Node B中接收窗的配置方法。     

基于ML和ESPRIT方法的OFDMA上行链路频偏估计算法

由于载波频偏会给正交频分多址接入OFDMA系统带来子载波之间干扰,从而造成多用户之间的干扰,导致系统性能下降。该文提出一种基于ESPRIT和ML方法联合估计的频偏估计算法。该算法首先使用ESPRIT方法估计出多个可能的频偏构成的子集,然后使用最大似然估计方法在这个有限子集合中搜索出估计的频偏。该算法解决了使用似然估计进行多维搜索的问题,大大降低了算法的复杂度,同时解决了多个频偏估计的问题。     

Self-Organization Approaches for Optimization in Cognitive Radio Networks

Cognitive radio （CR） is regarded as a promising technology for providing a high spectral efficiency to mobile users by using heterogeneous wireless network architectures and dynamic spectrum access techniques. However, cognitive radio networks （CRNs） may also impose some challenges due to the ever increasing complexity of network architecture, the increasing complexity with configuration and management of large-scale networks, fluctuating nature of the available spectrum, diverse Quality-of-Service （QoS） requirements of various applications, and the intensifying difficulties of centralized control, etc. Spectrum management functions with self-organization features can be used to address these challenges and realize this new network paradigm. In this paper, fundamentals of CR, including spectrum sensing, spectrum management, spectrum mobility and spectrum sharing, have been surveyed, with their paradigms of self-organization being emphasized. Variant aspects of self- organization paradigms in CRNs, including critical functionalities of Media Access Control （MAC）- and network-layer operations, are surveyed and compared. Furthermore, new directions and open problems in CRNs are also identified in this survey.