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Pseudo-handover based subchannel and power adaptation scheme for interference mitigation in OFDMA two-tier femtocell networks

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The Journal of China Universities of Posts and Telecommunications 2011年第3期18卷 8-15页

作者： LI Hong-jia HU Dan XU Xiao-dong TAO Xiao-feng ZHANG Ping Wireless Technology Innovation Institute Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

In the two-tier femtocell network, a central macroceU is underlaid with a large number of shorter range femtocell hotspots, which is preferably in the universal frequency reuse mode. This kind of new network architecture brings about urgent challenges to the schemes of interference management and the radio resource allocation. Motivated by these challenges, three contributions are made in this paper： 1） A novel joint subchannel and power allocation problem for orthogonal frequency division multiple access （OFDMA） downlink based femtocells is formulated on the premise of minimizing radiated interference of every Femto base station. 2） The pseudo-handover based scheduling information exchange method is proposed to exchange the co-tier and cross-tier information, and thus avoid the collision interference. 3） An iterative scheme of power control and subchannel is proposed to solve the formulated problem in contribution 1）, which is an NP-complete problem. Through simulations and comparisons with four other schemes, better performance in reducing interference and improving the spectrum efficiency is achieved by the proposed scheme.

关键词： femtocell OFDMA interference mitigation resource management power control

Fingerprint-Based Millimeter-Wave Beam Selection for interference mitigation in Beamspace Multi-User MIMO Communications

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Computers, Materials & Continua 2021年第1期66卷 59-70页

作者： Sangmi MoonHyeonsung Kim Seng-Phil Hong Mingoo Kang Intae Hwang Department of Electronic Engineering Chonnam National UniversityGwangju61186Korea Hancom With Inc. Seongnam-si13493Korea Division of Information&Telecommunication Hanshin UniversityOsan-si18101Korea

Millimeter-wave communications are suitable for application to massive multiple-input multiple-output systems in order to satisfy the ever-growing data traffic demands of the next-generation wireless ***,their practical deployment is hindered by the high cost of complex hardware,such as radio frequency(RF)*** this end,operation in the beamspace domain,through beam selection,is a viable ***,the conventional beam selection schemes focus on the feedback and exhaustive search *** addition,since the same beam in the beamspace may be assigned to a different user,conventional beam selection schemes suffer serious multi-user *** addition,some RF chains may be wasted,since they do not contribute to the sum-rate ***,a fingerprint-based beam selection scheme is proposed to solve these *** proposed scheme conducts offline group-based fingerprint database construction and online beam selection to mitigate multi-user *** the offline phase,the contributing users with the same best beam are *** grouping,a fingerprint database is created for each *** the online phase,beam selection is performed for purposes of interference mitigation using the information contained in the group-based fingerprint *** simulation results confirm that the proposed beam selection scheme can achieve a signal-to-interference-plus-noise ratio and sum-rate performance which is close to those of a fully digital system,and having much higher energy efficiency.

关键词： Beam selection beamspace group-based fingerprint interference mitigation millimeter-wave

Continuous-Wave interference mitigation for Acquisition Method in Unified Carrier TT&C Systems

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Journal of Beijing Institute of Technology 2018年第4期27卷 575-583页

作者： Yunyun Wu Xiuli Yu Yongqing Wang School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

An interference mitigation for acquisition method,based on both energy center and spectrum symmetry detection,has been proposed as a possible solution to the problem of signal acquisition susceptibility to continuous-wave interference(CWI)in unified carrier telemetry,tracking,and command(TT&C)*** subcarrier modulation index as a priori condition,the existence of CWI is determined by comparing the energy center with the symmetric *** the presence of interference,the interference frequency point is assumed and culled;sequentially,the spectral symmetry is used to verify whether the signal acquisition is *** analysis,simulations,and experimental results demonstrate that the method can realize the acquisition of the main carrier target signal with an interference-to-signal ratio of 31 dB,which represents an improvement over the existing continuous-wave interference mitigation for acquisition methods.

关键词： unified carrier telemetry tracking and command(TT&C) interference mitigation signal acquisition spectrum symmetry

Range-angle-dependent beamforming for FDA-MIMO radar using oblique projection

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Science China(Information Sciences) 2022年第5期65卷 223-241页

作者： Lan LAN Guisheng LIAO Jingwei XU Shengqi ZHU Yuhong ZHANG National Key Laboratory of Radar Signal Processing Xidian University School of Electronic Engineering Xidian University

Frequency diverse array(FDA)-multiple-input and multiple-output(MIMO) radar is characterized with a range-angle-dependent transceive beampattern by introducing incremental frequencies among the transmit array elements and separating the transmitted waveforms with matched filtering in the receiver. In this respect, the paper aims to control the range-angle-dependent transceive beampattern for FDA-MIMO radar by designing the weight vector according to the desired response. At the design stage, the weight vectors to control the beampattern responses of different regions are devised by performing the orthogonal decomposition technique. Then, a filtering matrix using the oblique projection operator is constructed to filter the weight vectors for different regions, where two iterative algorithms are developed either considering concurrent or successive control of multiple regions. In such a way, a desired range-angle-dependent transceive beampattern is formed with simultaneously broadened nulls and a flat-top mainlobe. At the analysis stage,the method has been applied to interference mitigation in FDA-MIMO radar, where the mismatch exists both in the sidelobes and mainlobe. Simulated and measured results are provided to corroborate the effectiveness of the proposed methods.

关键词： FDA-MIMO radar range-angle-dependent beamforming weight vector orthogonal decomposition oblique projection interference mitigation

interference management for rate-constrained moving relay node in a heterogeneous network

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Science China(Information Sciences) 2014年第10期57卷 34-45页

作者： HUANG Sheng LI JianDong ZHAO LinJing HUANG JinJing Broadband Wireless Communications Laboratory Information Science InstituteState Key Laboratory of ISN Xidian University

Cooperative communication via a moving relay node(MRN) helps resolve both the poor quality of service(QoS) and limited battery-capacity problems of cell-edge vehicle user equipment(VUE). This paper investigates the performance of MRNs in a heterogeneous network(HetNet). MRNs as well as other small cells are expected to coexist in a complex manner. In such a HetNet, the inter-cell interference may degrade the expected improvement of MRNs, especially at the cell-edge. In this paper, we investigate the impact of intercell interference on the performance of MRNs. To alleviate this impact, we first formulated a general optimization problem for which it is intractable to find a global optimal solution. To have a practical solution with low computational complexity, we used a practical interference management algorithm that aimed to ensure that every MRN achieved its required minimum-rate while maximizing total network throughput. In the simulations, the proposed algorithm was observed to improve both the QoS and fairness of MRNs. Numerical results demonstrate that the proposed algorithm can offer an efficient trade-off between the performance of both the victim MRNs and aggressing femtocells.

关键词： moving relay node minimum-rate constraint heterogeneous network inter-cell interference sub-channel allocation interference mitigation

Null steering antenna beamforming utilizing space-time adaptive processing

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The Journal of China Universities of Posts and Telecommunications 2015年第4期22卷 51-55页

作者： Zeng Hao Ahmad Zeeshan Dong Tao Liu Ling School of Communications Engineering Chongqing University Space Star Technology Co. Ltd

A new architecture of null steering antenna based upon the technology of space-time adaptive processing（STAP） with optimized parameters is proposed. The new STAP antenna is comprised of multiple channels and each channel is a transversal filter. So separate sensor element for the reference signal is not required because the antenna gets the reference signal from the first sensor of the auxiliary array. Furthermore, the least mean square（LMS） algorithm is employed to calculate the weight vector. Detailed analysis about the relationship between noise power and output error is investigated. Compared with the traditional null steering antenna in space or space-time domain, the new approach obtains more freedom degrees and can suppress both the wideband and narrowband interferences more efficiently with deeper nulls. Simulation results shows that the proposed architecture outperforms the conventional STAP techniques for interference suppression.

关键词： null steering antenna STAP beamforming interference mitigation

Low PAPR Channel Estimation for OTFS with Scattered Superimposed Pilots

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China Communications 2023年第1期20卷 79-87页

作者： Wei Liu Liyi Zou Baoming Bai Teng Sun State Key Labs of Integrated Service Networks Xidian UniversityXi’an 710071China The 54th Research Institute of CETC Shijiazhuang Hebei 050081China

Orthogonal time frequency space(OTFS)modulation has been proven to be superior to traditional orthogonal frequency division multiplexing(OFDM)systems in high-speed communication ***,the existing channel estimation schemes may results in poor peak to average power ratio(PAPR)performance of OTFS system or low spectrum ***,in this paper,we propose a low PAPR channel estimation scheme with high spectrum ***,we design a multiple scattered pilot pattern,where multiple low power pilot symbols are superimposed with data symbols in delay-Doppler ***,we propose the placement rules for pilot symbols,which can guarantee the low ***,the data aided iterative channel estimation was invoked,where joint channel estimation is proposed by exploiting multiple independent received signals instead of only one received signal in the existing scheme,which can mitigate the interference imposed by data symbols for channel *** results shows that the proposed multiple scattered pilot aided channel estimation scheme can significantly reduce the PAPR while keeping the high spectrum efficiency.

关键词： OTFS channel estimation superimposed pilots PAPR interference mitigation

Spectral Coexistence between LEO and GEO Satellites by Optimizing Direction Normal of Phased Array Antennas

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China Communications 2018年第6期15卷 18-27页

作者： Chen Zhang Jin Jin Hao Zhang Ting Li Tsinghua Space Center Tsinghua University Technology and Engineering Center for Space Utilization Chinese Academy of Sciences

This paper addresses the spectral coexistence between LEO constellation and GEO belt for global distributed earth stations. A specific method is introduced to mitigate the in-line interference by tilting the direction normal of phased array antennas of LEO satellites, and the optimal direction is found by solving a non-linear programming problem. The simulation results prove that the proposed approach leads to greater link availability while guaranteeing the desired received signal level especially for low-latitude earth stations.

关键词： satellite constellation satellite communication spectral coexistence interference mitigation phased array

MAC Layer Resource Allocation for Wireless Body Area Networks

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ZTE Communications 2014年第3期12卷 13-21页

作者： Qinghua Shen Xuemin (Sherman) Shen Tom H.Luan Jing Liu Department of Electrical and Computer Engineering University of Waterloo School of Information Technology Deakin University Department of Electronic Engineering Shanghai Jiao Tong University

Wireless body area networks （WBANs） can provide low-cost, timely healthcare services and are expected to be widely used for e-healthcare in hospitals. In a hospital, space is often limited and multiple WBANs have to coexist in an area and share the same channel in order to provide healthcare services to different patients. This causes severe interference between WBANs that could significantly reduce the network throughput and increase the amount of power consumed by sensors placed on the body. There-fore, an efficient channel-resource allocation scheme in the medium access control （MAC） layer is crucial. In this paper, we devel-op a centralized MAC layer resource allocation scheme for a WBAN. We focus on mitigating the interference between WBANs and reducing the power consumed by sensors. Channel and buffer state are reported by smartphones deployed in each WBAN, and channel access allocation is performed by a central controller to maximize network throughput. Sensors have strict limitations in terms of energy consumption and computing capability and cannot provide all the necessary information for channel allocation in a timely manner. This deteriorates network performance. We exploit the temporal correlation of the body area channel in order to minimize the number of channel state reports necessary. We view the network design as a partly observable optimization prob-lem and develop a myopic policy, which we then simulate in Matlab.

关键词： medium access control (MAC) wireless body area networks (WBANs) resource allocation interference mitigation partially observable optimization