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Partial intersection sphere decoding with weighted voting for sparse rotated V-OFDM systems

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Science China(Information Sciences) 2018年第2期61卷 77-89页

作者： Qi FENG Xiang-Gen XIA naitong zhang School of Electronic Science and Engineering Nanjing University College of Information Engineering Shenzhen University Department of Electrical and Computer Engineering University of Delaware School of Electronics and Information Engineering Harbin Institute of Technology

Vector orthogonal frequency division multiplexing(V-OFDM) is a general system that builds a bridge between OFDM and single-carrier frequency domain equalization in terms of intersymbol interference level and receiver complexity. In this paper, we focus on a rotated V-OFDM system over a broadband sparse channel owing to its large time delay spread and fewer nonzero taps. In order to collect the multipath diversity,a simple rotation matrix is designed, independent of the number of subchannels at the transmitter. For the rotated V-OFDM receiver, a partial intersection sphere decoding with weighted voting method is proposed by exploiting the sparse nature of the multipath channel. The proposed receiver chooses the transmitted vector from the set with the maximum likelihood estimation generated using the partial intersection sphere decoding method. For an extreme case, such as when a candidate set is empty, which usually occurs at a low signal-to-noise ratio(SNR), an efficient weighted voting system is used to estimate the transmitted vectors symbol-by-symbol. Simulation results indicate that the proposed receiver improves the symbol error rate performance with reduced complexity, especially for low SNR scenarios.

关键词： vector orthogonal frequency division multiplexing sparse multipath channel partial intersection sphere decoding weighted voting diversity order

IDMA based MAI mitigation scheme with low complexity and low latency

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Journal of Systems Engineering and Electronics 2012年第6期23卷 791-801页

作者： Zuoliang Yin Xingpeng Mao Jun Cai naitong zhang School of Electronics and Information Engineering Harbin Institute of Technology Harbin 150001 R R. China Department of Computer and Electrical Engineering University of Manitoba Winnipeg R3T 5V6 Canada

High complexity and high latency are key problems for multiuser detection （MUD） to be applied to a mobile station in cellular networks. To tackle these problems, an interleave division multiple access （IDMA） based multiple access scheme, grouped spread IDMA （GSIDMA）, is proposed. In a GSIDMA system, lower complexity and latency for mobile stations can be achieved by appropriately dividing active users into different groups. The system model of GSIDMA is constructed and followed by analysing on its system capacity, complexity and latency, and bit error rate （BER） performance. The extrinsic information transfer （EXIT） chart is used to analyze the convergence behavior of the iteration process. The grouping method and interleavers-reuse issue for GSIDMA are also discussed preliminarily. The analyses and simulation results indicate that the complexity and latency of the proposed scheme are much lower than those of IDMA, whereas its BER performance is close to the latter. The properties of low complexity and low latency make it more feasible for the practical implementation.

关键词： grouped spread interleave division multiple access（GSIDMA） iterative multiuser detector （IMUD） low complexity lowlatency multiple access interference （MAI） mitigation.

A Novel Resource Allocation Algorithm based on Downlink and Uplink Decouple Access Scheme in Heterogeneous Networks

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China Communications 2016年第6期13卷 22-31页

作者： Laiwei Jiang Xuejun Sha Xuanli Wu naitong zhang Communication Research Center Harbin Institute of Technology

Traditional cellular network requires that a user equipment(UE) should associate to the same base station(BS) in both the downlink(DL) and the uplink(UL). Based on dual connectivity(DC) introduced in LTE-Advanced R12, DL/UL decouple access scheme has been proposed, which is especially suitable for heterogeneous networks(Het Nets). This paper is the pioneer to take the DL/UL decouple access scheme into consideration and develop a novel resource allocation algorithm in a two-tier Het Net to improve the total system throughput in the UL and ease the load imbalance between macro base stations(MBSs) and pico base stations(PBSs). A model is formulated as a nonlinear integer programming, and the proposed algorithm is a sub-optimal algorithm based on the graph theory. First, an undirected and weighted interference graph is obtained. Next, the users are grouped to let users with large mutual interferences to be assigned to different clusters. Then, the users in different clusters are allocated to different resource blocks(RBs) by using the Hungarian algorithm. Simulation results show that the proposed algorithm can provide great promotions for both the total system throughput and the average cell edge user throughput and successfully ease the load imbalance between MBSs and PBSs.

关键词：资源分配算法接入方案异构网络上行链路下行链路解耦非线性整数规划负载不平衡

On the Probability Density Function of the Real and Imaginary Parts in WFRFT Signals

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China Communications 2016年第9期13卷 44-52页

作者： Xiaolu Wang Lin Mei Zhenduo Wang naitong zhang Communications Research Center School of Electronics and Information EngineeringHarbin Institute Technology

Recently a Hybrid Carrier(HC) scheme based on Weighted-type Fractional Fourier Transform(WFRFT) was proposed and developed,which contains Single Carrier(SC) and Multi-Carrier(MC) synergetic transmission.The wide interest is primarily due to its appealing characteristics,such as the robust performances in different types of selective fading channels and a great deal of potential for secure communications.According to the literatures,the HC signal and SC or MC signal probability distributions are different.In particular,some benefits of this HC scheme are brought by the quasi-Gaussian distribution of WFRFT signals.However,until now researchers have only presented statistic properties through computer simulations,and the accurate expressions of signals are not derived yet.In this paper,we derive the accurate and rigorously established closed-form expressions of Probability Density Function(PDF) of WFRFT signal real and imaginary parts with a large number of QPSK subcarriers,and this PDF can describe the behavior of data modulated by WFRFT,avoiding the complex computation for extensive computer simulations.Furthermore,the components of PDF expression are described and analyzed,and it is revealed that the tendency of signal quasi-Gaussian changes with the increasingof the parameter α(α in(0,1]).To validate the analytical results,extensive simulations have been conducted,showing a very good match between the analytical results and the real situations.The contribution of this paper may be useful to deduce the closed form expressions of Bit Error Ratio(BER),the Complementary Cumulative Distribution Function(CCDF) of Peak to Average Power Ratio(PAPR),and other analytical studies which adopt the PDF.

关键词：概率密度函数信号虚部实部计算机模拟计算互补累积分布函数精确表达式分数傅里叶变换

Investigating path loss characteristics of UWB signals in vacancy indoor environment based on time-domain technique

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Journal of Systems Engineering and Electronics 2006年第2期17卷 296-302页

作者： Wang Yang zhang naitong Communication Research Center Harbin Inst. of Technology Harbin 150001 P.R. China

The path loss analysis model based on 5 rays in vacancy indoor environment is proposed. The relationship between multipath overlapping and the path loss is analyzed mathematically. Time-domain technique is introduced to compute reflection coefficient in a very short time interval. A 5 rays path loss calculation method, which is satisfactory accurate, is developed. 5 typical environments are involved to analyze and generalize the common path loss characteristics in vacancy indoor environment. The simulation result shows that the path loss can be characterized as 3 zones with different path loss exponent as distance between transmitter and receiver increasing.

关键词： UWB path Loss time-domain multipath indoor environment.

Characterizing Ultra-wide Band indoor line-of-sight wireless channel

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Journal of Systems Engineering and Electronics 2007年第4期18卷 673-678,697页

作者： Wang Yang zhang naitong zhang Qinyu zhang Zhongzhao Communication Research Center Harbin Institute of Technology Harbin 150001 P. R. China

By exploring the deterministic characteristics of the measurement data, a new propagation model with two deterministic clusters and stochastic arriving rays within each cluster is proposed. When considering the cumulative distribution function （CDF） of the three key channel statistics, the proposed model fits the measurement data better than SV/IEEE 802.15.3, a model which is known as a standard model for UWB indoor propagation channel. Therefore, with the additional knowledge of the specific environment geometry, the proposed model generating impulse responses ＂resemble＂ the measured channel impulse responses better than IEEE model. Moreover, the proposed model＇s parameters obtaining procedure is simplified by utilizing simple parameters of the environment.

关键词： UWB wireless channel propagation characteristic indoor channel.

Deconvolution techniques for characterizing indoor UWB wireless channel

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Journal of Systems Engineering and Electronics 2008年第4期19卷 688-693页

作者： Wang Yang zhang naitong zhang Qinyu zhang Zhongzhao Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

A deconvolution algorithm is proposed to account for the distortions of impulse shape introduced by propagation process. By finding the best correlation of the received waveform with the multiple templates, the number of multipath components is reduced as the result of eliminating the ＂phantom paths＂, and the captured energy increases. Moreover, it needs only a single reference measurement in real measurement environment （do not need the anechoic chamber）, which by far simplifies the templates acquiring procedure.

关键词： ultra-wide band channel model CLEAN algorithm CIR deconvolution.

Deterministic simulation of UWB indoor propagation channel

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Journal of Systems Engineering and Electronics 2008年第3期19卷 447-452页

作者： Wang Yang zhang naitong zhang Qinyu zhang Zhongzhao Communication Engineering Research Center Harbin Inst. of Technology Shenzhen Graduate School Shenzhen 518055 P. R. China Communication Research Center Harbin Inst. of Technology Harbin 150001 P. R. China

A site-specific model of UWB pulse propagation in indoor environment is addressed. The simulation utilizes the principles of geometrical optics （GO） for direct and reflected paths＇ tracing and the time domain technique for describing the transient electromagnetic field reflected from wall, floor, ceiling, and objects. The polarization of the received waveform is determined by taking into account the radiation pattern of the transmitting and receiving antennas, as well as the polarization changes owing to every reflection. The model provides more intrinsical interpretations for UWB pulse propagation in realistic indoor environment.

关键词： UWB time domain indoor propagation channel diffraction.

Performance analysis of an indoor UWB ranging system

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Journal of Systems Engineering and Electronics 2009年第3期20卷 450-456页

作者： zhang Tingting zhang Qinyu zhang naitong Xu Hongguang School of Electrical and Information Harbin Inst. of Technology Harbin 150001 P. R. China Harbin Inst. of Technology Shenzhen Graduate School Shenzhen 518055 P. R. China

To evaluate the ranging performance of impulse radio ultra wideband （IR-UWB） signals, an experiment is performed in a typical indoor environment. In order to mitigate the ranging error caused by theoretical algorithm and practical circuits, one way-time difference of the arrival （OW-TDOA） ranging method and corresponding approaches are proposed and carried out according to the structure of UWB transceivers. Generalized maximum likelihood （GML） estimator based on energy detection is applied for the time of arrival estimation. The obtained results show that this UWB ranging system can achieve a relative high ranging accuracy in a multipath environment （e.g. about 5 cm at ranges up to 6 m）, which is practical and meaningful for many sensor applications.

关键词： ranging impulse radio ultra wideband time of arrival energy detection multipath