一种基于高阶统计量的组合盲均衡新算法

基于高阶统计量的逆滤波器准则（IFC）和超指数迭代算法（SEA）已经被广泛地应用于解决盲均衡问题。Chi，Feng和Chen通过对两种算法的性能分析提出在特定的条件下SEA和IFC算法的得到的均衡器是等价的。基于这种等价性，文献中提出通过对这两种算法进行组合来提高算法性能的改进方案。采用这种改进的改进方案，将一种最新的改进的SEA算烈和IFC算法进行组合，提出一种收敛性又好，收敛速度又快的组合算法。     

基于支持向量机的非线性信道盲均衡算法研究

针对非线性信道盲均衡问题,考察了一种基于支持向量机的单输入单输出(SISO)盲均衡算法,该算法利用通信信号的常数模特性,将非线性盲均衡问题转化为非线性支持向量回归问题。在此基础上,本文利用分集技术,将该算法拓展至单输入多输出(SIMO)的情况。对两种算法进行的计算机仿真表明,基于支持向量机的SISO盲均衡算法能够有效地抑制信道中的非线性码间干扰;本文提出新算法由于更好地利用了信道的时空特性,具有剩余平均模误差小的优点。     

Turbo equalization of serially concatenated turbo codes using a predictive DFE-based receiver

This paper investigates the performance of various “turbo” receivers for serially concatenated turbo codes transmitted through intersymbol interference (ISI) channels. Both the inner and outer codes are assumed to be recursive systematic convolutional (RSC) codes. The optimum turbo receiver consists of an (inner) channel maximum a posteriori (MAP) decoder and a MAP decoder for the outer code. The channel MAP decoder operates on a “supertrellis” which incorporates the channel trellis and the trellis for the inner error-correcting code. This is referred to as the MAP receiver employing a SuperTrellis (STMAP). Since the complexity of the supertrellis in the STMAP receiver increases exponentially with the channel length, we propose a simpler but suboptimal receiver that employs the predictive decision feedback equalizer (PDFE). The key idea in this paper is to have the feedforward part of the PDFE outside the iterative loop and incorporate only the feedback part inside the loop. We refer to this receiver as the PDFE-STMAP. The complexity of the supertrellis in the PDFE-STMAP receiver depends on the inner code and the length of the feedback part. Investigations with Proakis B, Proakis C (both channels have spectral nulls with all zeros on the unit circle and hence cannot be converted to a minimum phase channel) and a minimum phase channel reveal that at most two feedback taps are sufficient to get the best performance. A reduced-state STMAP (RS-STMAP) receiver is also derived which employs a smaller supertrellis at the cost of performance.     

2.5Gb/s光纤通信系统的电色散补偿技术研究

介绍了逐渐受到更多关注的高速光纤通信系统的电色散补偿(EDC)技术.我们将研究对象放在了采用啁啾DFB激光器、直接调制方式的2.5Gb/s高速光纤通信系统,通过仿真得到:啁啾系数为2的DFB激光器传输400km后经过8抽头判决反馈均衡器处理可有效地消除色散导致的码间干扰.     

Experimental implementation of a low-frequency global sound equalization method based on free field propagation

An experimental implementation of a global sound equalization method in a rectangular room using active control is described in this paper. The main purpose of the work has been to provide experimental evidence that sound can be equalized in a continuous three-dimensional region, the listening zone, which occupies a considerable part of the complete volume of the room. The equalization method, based on the simulation of a progressive plane wave, was implemented in a room with inner dimensions of 2.70 m × 2.74 m × 2.40 m. With this method, the sound was reproduced by a matrix of 4 × 5 loudspeakers in one of the walls. After traveling through the room, the sound wave was absorbed on the opposite wall, which had a similar arrangement of loudspeakers, by means of active control. A set of 40 digital FIR filters was used to modify the original input signal before it was fed to the loudspeakers, one filter for each transducer. The optimal arrangement of the loudspeakers and the maximum frequency that can be equalized is analyzed theoretically in this paper. The presented experimental results show that sound equalization was possible from 10 Hz to approximately 425 Hz in the listening zone. A flat frequency response with deviations within ±5 decibels from the desired value was achieved. A higher demanding performance with deviations within ±1.5 decibels from a flat frequency response was attained in the interval between 20 Hz and 280 Hz. At the same time, the impulse response was quite well approximated to a delayed delta function in the listening zone. Examples of the spatial distribution of the sound field are also shown.     

WDM系统PMD自适应补偿的研究

根据非线性耦合薛定谔方程,得到了在8×40 Gb/s波分复用(WDM)系统传输后各个信道归零码(RZ)的眼图以及各个信道的偏振度(DOP).以DOP作为反馈信号,采用最坏信道补偿方案对几个性能最坏的信道进行了自适应补偿.补偿结果表明,补偿后信道的DOP值以及眼图张开度都有明显的改善,说明此种补偿方案能有效地改善WDM系统的性能.     

基于FB-FDE的地空通信窄带干扰抑制方法

提出了一种基于滤波器组的单载波频域均衡(FB-FDE)技术的窄带干扰抑制方法,该方法在多径时延较大的地空宽带通信中具有很强的窄带干扰抑制能力。从理论上详细分析了基于滤波器组的窄带干扰抑制技术能够克服基于FFT频域均衡缺点的主要原因,并在此基础上提出了基于自适应子带合并的算法。理论分析和仿真试验均表明,该方法抑制窄带干扰能力强,运算简单,适于工程实现。     

无线信道中的单载波频域均衡技术研究

介绍了单载波频域均衡技术的原理,与单载波时域均衡以及多载波OFDM系统进行了比较。该技术结合了两者的优点:能有效对抗多径信道,且具有较低的复杂度;降低了峰均比和对载波频偏、相位噪声的敏感性,因而在无线通信领域具有广阔的应用前景。     

一种并行的软判决引导常数模盲均衡算法

介绍了一种常数模与软判决引导结合的盲均衡算法CMA SDD。该算法克服了CMA收敛速度慢、稳态误差大的缺点,同时可以纠正相位偏转。仿真表明,在高信噪比(SNR)条件下,两种算法的稳态均方误差相近,而CMA SDD算法的收敛速度更快;在低信噪比条件下,CMA SDD算法可以获得更快的收敛速度和更低的稳态均方误差。     

频选MIMO信道下低复杂度PDA SIC算法

为了同时消除频率选择性MIMO系统中的天线间干扰（MAD和码间干扰（ISI），本文将基于信道矩阵QR分解的串行干扰消除（SIC）算法和概率数据辅助（PDA）均衡算法相结合，提出了一种低复杂度的软判决迭代均衡算法。该算法一方面很好地消除了MAI，另一方面将传统PDA算法中大量的矩阵运算简化为数值计算，降低了系统的计算复杂度，并获得了良好的性能。