基于复数径向基函数神经网络的自适应均衡器

本文对基于复数径向基函数网络（CRBFN）的自适应均衡器作了研究；提出了两种新的复数径向基函数网络结构的均衡器：正交CRBFN（OCRBFN）均衡器与非对称CRBFN（ACRBFN）均衡器；并在此基础上提出了这两种自适应均衡器的训练算法．模拟结果表明对于线性信道或非线性信道这两种基于CRBFN均衡器的收敛性能比文献［2，5」中的均衡器优越，具有一定的实用价值．

基于二阶,四阶矩的QAM系统盲均衡准则

本文研究了ＱＡＭ系统的盲均衡问题，提出了一个基于二阶，四阶矩的统计量匹配盲均衡准则，并由此导出了一种新的盲均衡算法可以从而也加深了对盲均衡的理论认识。

Soft Direct-Adaptation Based Bidirectional Turbo Equalization for MIMO Underwater Acoustic Communications

This paper proposes a soft direct-adaptation based bidirectional turbo equalizer for multiple-input multiple-output underwater acoustic communication systems. Soft, rather than hard, direct-adaptation based equalizer combined with the fast self-optimized least mean square algorithm is employed to achieve a faster convergence rate, and the second-order phase-locked loop is embedded into the equalizer to track the time-varying channel. Meanwhile, by utilizing a weighted linear combining scheme, the conventional soft direct-adaptation based equalizer is combined with the time-reversed soft direct-adaptation based equalizer to exploit bidirectional diversity and mitigate error propagation. Both the simulation and experimental results demonstrate that the soft direct-adaptation based bidirectional turbo equalizer outperforms the single-direction soft direct-adaptation based turbo equalizer, and achieves a faster convergence rate than the hard direct-adaptation based bidirectional turbo equalizer.

Fractionally Spaced Equalization Algorithms in 60GHz Communication System

Several fractionally spaced equalizers(FSE) which could be used in 60 GHz systems are presented in this paper. For 60 GHz systems, low-power equalization algorithms are favorable. We focus on FSE in both time domain(TD) and frequency domain(FD) in order to meet different complexity requirements of 60 GHz systems. Compared with symbol spaced equalizer(SSE), FSE can relax the requirement of sampling synchronization hardware significantly. Extensive simulation results show that our equalization algorithms not only eliminate ISI efficiently, but are also robust to timing synchronization errors.

Power Equilibrium in Dense Wavelength Division Multiplexing Optical Communication Systems

The disequilibrium of the optical power among different channels is analyzed for the dense wavelength division multiplexing optical communication systems. And the new technologies and devices for optical amplifying, filtering, adding /dropping,etc,have been reviewed, which can be used to equalize dynamically the optical power in optical networks.

A Novel Two-Stage Dynamic Spectrum Sharing Scheme in Cognitive Radio Networks

In order to enhance the efficiency of spectrum utilization and reduce communication overhead in spectrum sharing process, we propose a two-stage dynamic spectrum sharing scheme in which cooperative and noncooperative modes are analyzed in both stages. In particular, the existence and the uniqueness of Nash Equilibrium(NE) strategies for noncooperative mode are proved. In addition, a distributed iterative algorithm is proposed to obtain the optimal solutions of the scheme. Simulation studies are carried out to show the performance comparison between two modes as well as the system revenue improvement of the proposed scheme compared with a conventional scheme without a virtual price control factor.

Multi-Channel Iterative FDE for Single Carrier Block Transmission over Underwater Acoustic Channels

Recently, single carrier block transmission(SCBT) has received much attention in high-rate phase-coherent underwater acoustic communication.However,minimum-mean-square-error(MMSE) linear FDE may suffer performance loss in the severely time dispersive underwater acoustic channel. To combat the channel distortion, a novel multi-channel receiver with maximum ratio combining and a low complex T/4 fractional iterative frequency domain equalization(FDE) is investigated to improve diversity gain and the bit error rate(BER) performance. The proposed method has been verified by the real data from a lake underwater acoustic communication test in November 2011. At 1.8 km, the useful data rates are around 1500 and 3000 bits/s for BPSK and QPSK respectively. The results show the improvements of system performance. Compared with MMSE FDE system, the output SNR improvement is 6.9 d B, and the BER is from 10-3 to no error bits for BPSK. The output SNR improvement is 5.3 d B, and the BER is from 1.91×10-2 to 2.2×10-4for QPSK.

Blind Channel Equalization Algorithm Based on Dual Unscented Kalman Filter for Chaotic Multi-Input Multi-Output Communication Systems

To reduce channel noise,fading,and inter-user interference effectively in the chaotic communication systems with multi-user,a blind channel equalization algorithm based on dual unscented Kalman filter algorithm is proposed.Assuming that the coefficients of a multi-input multi-output (MIMO) channel can be described by an autoregressive model,two separate state-space representations are used for the signals and coefficients.Then two unscented Kalman filters are used to estimate chaotic signals and channel coefficients simultaneously.The simulation results indicate that the algorithm can effectively track the coefficients of the multi-path fading channel in chaotic MIMO communication systems at a fast convergence speed.

A 10Gb/s combined equalizer in 0.18μm CMOS technology for backplane communication

This paper presents a lOGb/s highspeed equalizer as the frontend of a receiver for backplane communication. The equalizer combines an analog equalizer and a twotap decisionfeedback equal izer in a halfrate structure to reduce the intersymbolinterference （ISI） of the communication chan nel. By employing inductive peaking technique for the highfrequency boost circuit, the bandwidth and the boost of the analog equalizer are improved. The decisionfeedback equalizer optimizes the size of the CMLbased circuit such as D flipflops （DFF） and multiplex （MUX）, shortening the feedback path delay and speeding up the operation considerably. Designed in the 0. 181μm CMOS technology, the equalizer delivers 10Gb/s data over 18in FR4 trace with 28dB loss while drawing 27mW from a 1.8V supply. The overall chip area including pads is 0. 6 -0.7mm2.

Design of a transversal equalizer for electronic dispersion compensation in optical communication links

A programmable transversal equalizer for electronic dispersion compensation(EDC) in optical fiber communication systems is developed.Based on the SiGe technology with a cut-off frequency of 80 GHz,the equalizer consists of 6 seriesparallel amplifiers as delay units and 7 Gilbert variable gain amplifiers as taps,which ensure that the equalizer can work at the bit rate of 10 Gb/s.With different tap gains,the forward voltage gain of the transversal equalizer varies,which demonstrates that the equalizer has various filtering characteristics such as low pass filtering,band pass filtering,band reject filtering,and notch filtering,so it can effectively simulate the inverse transfer function of dispersive channels in optical communications,and can be used for compensating the inter-symbol interference and other nonlinear problems caused by dispersion.The equalizer(including pads) occupies an area of 0.40 mm × 1.08 mm,and its total power dissipation is 400 mW with 3.3 V power supply.

An IIR adaptive electronic equalizer for polarization multiplexed fiber optic communication systems

An electronic digital equalizer for polarization multiplex coherent fiber optic communication systems is designed to compensate polarization mode dispersion (PMD) and residual chromatic dispersion (CD) of transmission channel. The proposed equalizer is realized with fraction spaced infinite impulse response (IIR) butterfly structure with 21 feedforward taps and 2 feedback taps. Compared with finite impulse response (FIR) structure, this structure can reduce implementation complexity of hardware under the same condition. To keep track of the random variation of channel characteristics, the filter weights are updated by least mean square (LMS) algorithm. The simulation results show that the proposed equalizer can compensate residual chromatic dispersion (CD) of 1600 ps/nm and differential group delay (DGD) of 90 ps simultaneously, and also can increase the PMD and residual CD tolerance of the whole communication system.