TOA数据处理对NLOS环境下定位精度的改善

基于移动通信环境中非视距(NLOS)传播时延服从指数分布的特性,提出了一种改善移动台定位精度的波达时间(TOA)数据处理方法.NLOS传播时延是TOA测量误差的一部分,是基站与移动台距离的指数函数,具有正偏置的特性,因此TOA测量值越大其误差越大.对所有的TOA测量数据进行分析,仅保留误差最小的3个,然后再采用最小二乘(LS)法估计移动台的坐标.仿真结果表明,该TOA数据处理方法能够明显改善NLOS传播环境下的定位精度,在系统测量误差较小时对LOS传播条件下的定位精度几乎没有影响.     

A computationally efficient method of timing and phase estimation in TDMA systems using a preamble sequence

Optimum and near optimum methods of burst parameter estimation based on the discrete Fourier transform are presented. The methods are applicable to single sample per symbol demodulators when the burst preamble is chosen to be a discrete frequency component at one quarter of the symbol rate. The proposed methods do not require the squaring of the signal, and hence avoid the loss associated with squaring the noise components. The optimum method is shown to reach the Cramer-Rao bound for symbol timing and carrier phase estimation for the chosen preamble, whereas the more computationally efficient method shows a loss of 1.0dB and yields information regarding the timing offset only. The performances of the two methods in the presence of carrier frequency offset and additive white Gaussian noise are analysed, and implementations are given together with a comparison of the respective computational complexities.     

Joint design of precoder and receiver in cognitive radio networks using an MSE criterion

We consider a single-user multiple-input multiple output (MIMO) transmission from secondary base station (SBS) in cognitive radio network where there is one primary user to which spectrum is licensed. It is assumed that coexistence of secondary network is allowed if interference power from the secondary network measured at primary user (PU) can be kept below a given threshold. In this paper, joint design problem of precoder and receiver is treated using mean-squared error (MSE) criterion between transmitted signal and its estimate at the receiver. Due to constraint on interference power measured at the PU, it is not possible to find an optimal solution in closed form. Therefore, a suboptimal solution with low complexity is proposed in closed form. Simulation results show that the MSE and bit error rate (BER) performances of the proposed scheme are 1.5-4.0 dB better than those of a conventional capacity-maximization scheme when the received signal-to-noise ratio (SNR) is high, and they converge to their lower bounds, i.e., those of an MSE-based scheme without considering the PU interference constraint, as the received SNR increases.     

Fabrication of a new micro bio chip and flow cell cytometry system using Bio-MEMS technology

This experiment was required the base technology's of micro packaging technology, micro fluidic technology, micro optical technology and electricity signal processing technology. This experiment emphasizes Bio-MEMS (micro electro mechanical system) technology and application. Material of chip was used the hydrophilic properties of good glass more than that of PDMS (poly dimethylsiloxane) and PMMA (poly methyl methacrylate). Method to use in chip manufacture is the BOEM (buffered oxide etchant method), ECDM (electro chemical discharge method) and UVAM (UV sensitive adhesives method). It is possible to measure the characteristics of various DNA. Therefore, those applications may be useful in other MEMS technology and optical science of biotechnology field [H.M. Shapiro, M.D, Practical Flow Cytometry, third ed., 1995; Z.D. kiewicz, J.P. Robinson, H.A. Crissman, Flow Cytometry, second ed., 1995].