Applied Mechanics and Materials Vols. 195-196

Abstract: According to SMART 2020, Internet and ICT (Information and communication technology) could reduce emissions by 15 percent in annual energy costs by 2020. One of the main methods to reduce the energy costs in communication system is to reduce the transmitting power of eNBs. In our study, we explore the problem of downlink energy saving for LTE/LTE-A network based on Orthogonal Frequency Division Multiplexing (OFDM). We propose an adaptive eNB transmitting power allocation scheme based on inter-eNB coordination. This power allocation scheme works in distributive way by being formulated as an evolutionary potential game. Numerical results prove that our proposed algorithm notably reduces the overall transmitting power, while throughputs of either overall or edge users are guaranteed at the same time.

Abstract: In order to speed up the vehicles through the expressway toll station and reduce traffic congestion, we analysed of the No-waiting ETC(Electronic Toll Collection System) of expressway unifying the ETC theory and the RFID(Radio Frequency Identification Devices) technology. Firstly, we analysed system's hierarchy architecture, then detailed analysed the basic component of system, and designed the workflow and composing of functional modules, finally, established the model of ETC system of expressway based on RFID, it provides more practical guidance scheme for expressway ETC system.

Abstract: As the development of carbon diocide sensors and communication technology, the method for monitoring the concentration of carbon dioxide is more and more advanced, especially the traditonal methods have the disadvantage of the low accuracy and inconvenience on use. This paper puts forward a wireless sensor networks based on TC35 module and the method of the signal transmitting. Through the application of wireless technology, the MCU could send the carbon diocide concentration data from the carbon diocide sensor which is based on the NDIR technology to the process module, and the system could achieve the distant measurement of the carbon diocide displayed on the LED. Comparing with wire monitor system, wireless monitor system omits linking lines and it has good application prospect.

Abstract: For the acquisition of week direct sequence spread spectrum (DSSS) signal in dynamic environment, an acquisition algorithm using MAX /TC criterion on bi-dimensional search region in noncoherent integrations is proposed. Detection performance of the proposed acquisition algorithm is deduced and the deduced formulas are simple and practicable. Based on these formulas, parameter design method is given for low signal-to-noise ratio (SNR). Computer simulation results demonstrate the correctness of the conclusion and effectiveness of parameter design method.

Abstract: The fractional Fourier transform (FrFT) used to process linearly frequency modulated (LFM) signals is applied in the differentiation and parameters estimation of LFM radar signals. The performance of the LFM signals detection and parameters estimation through FrFT are studied when the signal-noise ratio (SNR) is low. The situation is set and the demonstration routine through simulations is made so that the performance on the chirp rate estimation and the central frequency estimation of LFM signals through FrFT is tested, the time used to obtain parameter estimation results through computer simulations is compared. The simulation results demonstrate that the method through FrFT could be used to differentiate LFM radar signals and to estimate parameters of LFM radar signals when the SNR is low.

Abstract: A low-power, wideband signaling receiver for data transmission through a human body was presented in this paper. The receiver utilized a novel implementation of energy-efficient wideband impulse communication that uses the human body as the transmission medium, provides low power consumption, high reception sensitivity. The receiver consists of a low-noise amplifier, active balun, variable gain amplifier (VGA) Gm-C filter, comparator, and FSK demodulator. It was designed with 0.18um CMOS process in an active area of 1.54mm0.414mm. Post-simulation showed that the receiver has a gain range of-2dB~40dB. The receiver consumes 4mW at 1.8V supply and achieves transmission bit energy of 0.8nJ/bit.

Abstract: A dosimetry study is made for experiments on cultured cells exposed to 900 MHz microwave in the transverse electromagnetic (TEM) chamber. The exposure is characterized by the intensity and homogeneity of the specific absorption rate (SAR), as well as the exposure-induced temperature rise. The SAR distribution is calculated by using the finite-difference time-domain (FDTD) algorithm of the Maxwell equations. The finite-difference formulation of the bioheat conduction equation is used to calculate the temperature rise of the in vitro environment. Evaluations of the SAR and temperature are performed systematically for scenarios including two formations of cultured cells, two maximum fields, and four polarizations of the Petri dish holding the cell culture. The exposure is optimized by selecting scenarios with the highest SAR intensity, the best SAR homogeneity, and the effective temperature control.

Abstract: Soft-output complex list sphere decoding algorithm is a low-complexity MIMO detection algorithm and its BER performance approximates that of Maximum-Likelihood. However, it has a problem of not fixed complexity, and which make it very difficult to implement. To resolve this and try best to retain the advantages of the algorithm, a modified algorithmfixed complex list sphere decoding algorithm was proposed. Based on LTE TDD system, this paper studies the performance of the FCLSD algorithm. The simulation results show that: the BER performance of the FCLSD algorithm is close to that of the CLSD algorithm. However, when the number of antennas and modulation order increasing, the FCLSD algorithm is non-constrained of spherical radius and has fixed complexity. In addition, hardware implementation of the FCLSD algorithm could be carried out by parallel processing, thereby greatly reducing the algorithm complexity. So it is a high-performance algorithm of great potential.

Abstract: To solve the problem of blind source separation, a novel algorithm based on multiset canonical correlation analysis is presented by exploiting the different temporal structure of uncorrelated source signals. In contrast to higher order cumulant techniques, this algorithm is based on second order statistical characteristic of observation signals, can blind separate super-Gaussian and sub-Gaussian signals successfully at the same time with relatively light computation burden. Simulation results confirm that the algorithm is efficient and feasible.

Abstract: A new direction of arrival (DOA) estimation method is proposed for coherent GPS signals, which applies to the GPS receiver with rich multipath, strong interference and low SNR. In this method, the interference is first suppressed by projecting the received signal onto the interference orthogonal subspace. Afterwards, the noise is eliminated by the spatial difference matrix. Then, the coherent GPS signals are decorrelated by the reconstructed Toeplitz matrix, and the DOA estimation is improved by a new constructed matrix. The proposed method can obtain more accurate DOA estimation for coherent GPS signals with strong interference and low SNR in the GPS receiver. Simulation results demonstrate the effectiveness and efficiency of the proposed method.