Advanced Materials Research Vols. 760-762

Abstract: A low voltage, low power up-conversion mixer is presented here for 2.4GHz wireless sensor networks (WSN). It was based on a double-balanced Gilbert cell type. The current-reuse technique was used to reduce the power consumption and negative-resistance compensation technique was used to improve the conversion gain. The mixer was designed in 0.18μm RF CMOS technology, and was simulated with Cadence SpectreRF. The simulation results indicate that the conversion gain is 6.37dB, the noise figure is 15.36dB and the input 1dB compression point is-10.3dBm, while consuming 1mA current for operating voltage at 1V.

Abstract: For Fiber-Grating Perimeter-Intrusion alarm system, a Fiber-Grating intelligent adaptive alarm algorithm based on wavelet analysis and difference algorithm was proposed. The algorithm precedes the real-time waveform by wavelets decomposition, and acquired the assertion values of each subband by difference calculation. Through the method of comparing the assertion value of some subband, intelligent adaptive alarm system was realized. The experiments indicate that the proposed algorithm can give an alarm for illegal intrusion with good performance and false alarm below 1.5%, and it provides a promising application prospect for intelligent adaptive alarm.

Abstract: This paper introduces a 2.4 GHz down-conversion quadrature mixer which applied in the Wireless Sensor Network (WSN). The mixer uses a folded structure which is modified based on the conventional Gilbert mixer. It is designed in 0.18μm RF CMOS process with a low supply voltage of 1V. The post-simulation results show that the mixer achieves a conversion gain (CG) of 9.0dB, the input 1dB compression point (IP_1dB) of-7.6dBm, the third-order input intercept point (IIP3) of 2.2dBm, and the single side-band (SSB) noise figure (NF) is 13.9dB. The mixer core consumes current about 1.2mA from a 1V power supply.

Abstract: Source encoding algorithm has been widely concerned by the researchers, which aims to improve communication efficiency. In this paper, we put forward a new source encoding algorithm to decrease the redundancies between compiled code words in Shannon encoding. With the proposed algorithm, a code word is selected by considering whether the code is the prefix code of the other code words or not. The performance of the new encoding algorithm is investigated for both equal probability of source symbols and non-equal probability condition. Numerical results show that the proposed encoding algorithm can improve the encoding efficiency obviously, especially for the case of great probability differences between source symbols.

Abstract: The paper addresses the problems of speech distortion and residual musical noise introduced by conventional spectral subtraction (SS) method for speech enhancement. In this paper, we propose a modified SS algorithm for speech enhancement based on the masking properties of human auditory system. The algorithm computes the parameters α and β dynamically according to the masking thresholds of the critical frequency segments for each speech frame. Simulation results show that the proposed algorithm is superior to the conventional SS method, not only in the improvement of output SNR, but in the reduction of the speech distortion and residual musical noise.

Abstract: This paper introduced the asynchronous communication mechanism in 1394 bus network, and described 1394 network communication system for building the network topology, node architecture and asynchronous transfer mode communication. We proposed a 1394 bus network asynchronous communication mechanism with high-security, high-reliability. At last it verified the communication in the network with one control computer and four remote nodes.

Abstract: An unsymmetrical GaN based Doherty power amplifier (DPA) operating from 2.5GHz to 2.7GHz is presented in this paper. To achieve a good tradeoff among the output power, efficiency and bandwidth, the ladder-type multisection output matching networks are optimized for the carrier amplifier and the peaking amplifier, respectively. Measured with continuous wave (CW) signal, the broadband DPA provides more than 49dBm saturation power in the operating band. The drain efficiency is greater than 44% over 7dB back-off power. For a LTE-Advanced signal with 100MHz bandwidth, the drain efficiency is higher than 42% at an average output power of 41dBm, along with an adjacent channel leakage ratio (ACLR) of better than-49.9dBc after digital predistortion (DPD).

Abstract: In TD-LTE-A downlink, signal to leakage and noise ratio (SLNR) based beamforming can eliminate the co-channel interference and noise for multi-user MIMO mode effectively and can be realized more easily than the traditional ideal SINR based algorithms. Moreover, user scheduling can be combined with the SLNR based beamforming algorithm to obtain a better performance. Hence, in this paper, SLNR based beamforming is firstly compared with traditional beamforming algorithms, and then, a suboptimal maximum minimum SLNR (MMSLNR) scheduling strategy is proposed to improve the average BER performance and sum capacity of TD-LTE-A system and decrease the scheduling complexity as well.

Abstract: This paper analyzes the shortcomings of traditional handover algorithm, based on location aware switching the algorithm joined the GPS geolocation information to get the precise location and movement information to avoid unnecessary delay in the detection, switching between 3G and WIFI. The simulation results show that the performance of the algorithm with respect to traditional purely based on the received power switching algorithm significantly improve.

Abstract: This paper presents a low power low voltage 7bit 16MS/s SAR ADC (successive approximation register analog-to-digital converter) for the application of ZigBee receiver. The proposed 7-bit ADC is designed and simulated in 180nm RF CMOS technology. Post simulation results show that at 1.0-V supply and 16 MS/s, the ADC achieves a SNDR (signal-to-noise-and-distortion ratio) and SFDR (Spurious Free Dynamic Range) are 43.6dB, 57.4dB respectively. The total power dissipation is 228μW, and it occupies a chip area of 0.525 mm². It results in a figure-of-merit (FOM) of 0.11pJ/step.