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Power allocation in cooperative MIMO systems under individual power constraints

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The Journal of China Universities of Posts and Telecommunications 2011年第5期18卷 1-6页

作者： YANG Shan cui qi-mei XU Yue-qiao LUO Yuan Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

allocation （PA） plays an important role in capacity improvement for cooperative multiple-input multipleoutput （Co-MIMO） systems. Many contributions consider a total power constraint （TPC） on the sum of transmit power from all nodes in addressing PA problem. However, in practical implementations, each transmit node is equipped with its own power amplifier and is limited by individual power constraint （IPC）. Hence these PA methods under TPC are not realizable in practical systems. Meanwhile, the PA problem under IPC is essential, but it has not been studied. This paper extends the traditional non-cooperative water-filling PA algorithm to IPC-based Co-MIMO systems. Moreover, the PA matrix is derived based on the compound channel matrix from all the cooperative nodes to the user. Therefore, the cooperative gain of the IPC-based Co-MIMO systems is fully exploited, and further the maximal instantaneous capacity is achieved. Numerical simulations validate that, under the same IPC conditions, the proposed PA scheme considerably outperforms the non-cooperative water-filling PA and uniform PA design in terms of ergodic capacity.

关键词： power allocation cooperative MIMO individual power constraint ergodic capacity

CRLB analysis of wireless cognitive location with different short-range measurements

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The Journal of China Universities of Posts and Telecommunications 2008年第2期15卷 1-6页

作者： cui qi-mei LIU Jun TAO Xiao-feng ZHANG Ping Key Laboratoryof Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China

Because of the wide application and great market potential of location-aware services, the research of wireless location techniques for the fourth generation （4G） mobile communications is being paid more attention. Wireless cognitive location （WCL） techniques for next generation wireless networks have been proposed in recent years. This article investigates the changes of the positioning accuracy of WCL algorithm when different methods are adopted to measure the short-range （SR） information. By fJrst completing Cramer-Rao lower bound （CRLB） analysis of the WCL algorithm with SR measurements based on time of arrival （TOA） and received signal strength （RSS）, it is discovered that TOA-based or time difference of arrival （TDOA） -based SR measurement can make WCL algorithms achieve higher accuracy than RSS mode, which is also verified by numerical simulation in the article. The conclusions can instruct the design of novel WCL-based location algorithms.

关键词： wireless cognitive location short range (SR) longrange (LR) Cramer-Rao lower bound (CRLB)

SER bound for ordered ZF-SIC receiver in M-QAM MIMO system

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The Journal of China Universities of Posts and Telecommunications 2010年第1期17卷 51-55页

作者： HAN Juan cui qi-mei TAO Xiao-feng ZHANG Ping Wrlreless Technology Innovation Institute Beijing University of Posts and Telecommtmications Beijing 100876 China Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Pnsts and Telecommunications Beijing 100876 China

With the advances of the 4th generation （4G） mobile communications targeting multi-user QoS-guaranteed multimedia services, multiple input multiple output （MIMO） combined with multi-level quadrature amplitude modulation （M-QAM） technique gains great popularity for its capability of supporting high data rate. In this article, the statistical distribution of signal to noise plus interference ratio （SINR） in each recursive step of optimal ordered zero-forcing perfect successive interference cancellation （ZF-OOPSIC） detection is deduced based on order statistics theory. The symbol error rate （SER） of M-QAM MIMO system with ZF-OOPSIC detector is analyzed under fiat Rayleigh fading channel. This precise analytical SER result could be taken as the lower bound of various zero-forcing ordered successive interference cancellation （ZF-OSIC） receivers. Combining the analytical SER expression for linear zero-forcing （ZF） receiver as upper bound, the rough range of SER for various ZF-OSIC detectors could be obtained. Monte Carlo （MC） simulations validate the analytical results and prove the conclusions.

关键词： SER ZF ordered successive interference cancel (SIC) M-QAM MIMO

A novel TOA estimation method with effective NLOS error reduction

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The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 32-37页

作者： ZHANG Yi-heng cui qi-mei LI Yu-xiang ZHANG Ping Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Ministry of Education Wireless Technology Innovation Institute (WTI) Beijing 100876 China

It is well known that non-line-of-sight （NLOS） error has been the major factor impeding the enhancement of accuracy for time of arrival （TOA） estimation and wireless positioning. This article proposes a novel method of TOA estimation effectively reducing the NLOS error by 60%, comparing with the traditional timing and synchronization method. By constructing the orthogonal training sequences, this method converts the traditional TOA estimation to the detection of the first arrival path （FAP） in the NLOS multipath environment, and then estimates the TOA by the round-trip transmission （RTT） technology. Both theoretical analysis and numerical simulations prove that the method proposed in this article achieves better performance than the traditional methods.

关键词： TOA estimation NLOS error B3G

Cooperative localization for next-generation converged networks with closed-form solution

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The Journal of China Universities of Posts and Telecommunications 2009年第5期16卷 56-61页

作者： ZHANG Yi-heng cui qi-mei ZHANG Ping TAO Xiao-feng Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China Wireless Technology Innovation Institute Beijing University of Posts and Telecommunications Beijing 100876 China Research Institute of Highway (RIOH) Transport Consulats Ltd Beijing 100088 China

In this article, a novel cooperative wireless localization scheme based on information fusion is proposed. The scheme combines large-scale arrival time and small-scale distance measurements obtained from the next-generation converged networks. The maximum likelihood （ML） estimate of the terminal＇s position is derived with closed-form solution, and the Cramer-Rao lower bound （CRLB） of the estimate error is investigated. Both theoretical analysis and simulation results verify that the proposed localization scheme can significantly enhance the location precision. Moreover, the mean square error of position estimate approximates the CRLB when the number of reference stations increases, which indicates that the proposed ML estimator is asymptotically efficient.

关键词： cooperative localization time of arrival (TOA) next-generation converged network large scale small scale

Effective resource scheduling scheme considering scheduling relevancy for downlink joint transmission system

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The Journal of China Universities of Posts and Telecommunications 2012年第5期19卷 16-25页

作者： LI Xiao-na cui qi-mei MU Yan-lin TAO Xiao-feng Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and TelecommunicationsBeijing 100876China

Coordinated multi-point （CoMP） transmission is a promising technique to improve both cell average and cell edge throughput for long term evolution-advanced （LTE-A）. For CoMP joint transmission （CoMP-JT） in heterogeneous scenario, if joint transmission （JT） users are firstly scheduled, other non-JT users will not be allocated sufficient resources, i.e., scheduling relevancy exists in the users under different cells in the same coordination cluster. However, the CoMP system throughput will decline remarkably, if the impact of scheduling relevancy is not considered. To address this issue, this paper proposes a novel scheduling scheme for CoMP in heterogeneous scenario. The principles of the proposed scheme include two aspects. Firstly, this scheme gives priority to user fairness, based on an extended proportional fairness （PF） scheduling algorithm. Secondly, the throughput of the coordination cluster should be maintained at a high level. By taking the non-CoMP system as a baseline, the proposed scheme is evaluated by comparing to random PF （RPF） and orthogonal PF （OPF） scheme. System-level simulation results indicate that, the proposed scheme can achieve considerable performance gain in both cell average and cell edge throughput.

关键词： CoMP JT resource scheduling relevancy cell edge throughput

Space time frequency coding for dual polarization MIMO in hybrid mobile satellite system

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The Journal of China Universities of Posts and Telecommunications 2013年第4期20卷 8-14页

作者： WANG Kai-dong GUO Ling-zhi TAO Xiao-feng cui qi-mei Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications

The hybrid mobile satellite system operating in a single frequency network （SFN） mode is increasingly becoming attractive. The combination of satellite component （SC） and terrestrial component （TC） promises a better quality of service （QoS）. Multimedia broadcast and multicast services （MBMS） are expected to be prevailed in this kind of system. Several space frequency （SF） or space time （ST） codes have been proposed to enhance the system performance due to the lack of reverse link and omni-directional transmission. However, they mostly consider the system with only one SC and one TC and fail to make full use of available diversities. This paper presents a novel way to realize the dual polarization multiple input multiple output （MIMO） transmission by using the space time frequency （STF） code. The theoretical analysis and simulations indicate that the application of STF code can improve the system performance dramatically. A higher diversity gain can be achieved due to the cooperative transmission of SC and TC, while the coding gain can be enhanced by the reusing of STF code between SCs or TCs. Even if some of the links are lost, it can still work properly and benefit from the STF code. The relative relay can result in a degradation up to 0.5 dB in the coding gain.

关键词： MIMO dual polarization hybrid mobile satellite system SFN STF code diversity gain

Optimal energy-efficient scheme for two-way relay channel using physical layer network coding

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The Journal of China Universities of Posts and Telecommunications 2011年第6期18卷 51-58页

作者： ZHOU Min cui qi-mei WANG Hui TAO Xiao-feng TIAN Hui MIKKO Valkama Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China Department of Communications Engineering Tampere University of Technology Tampere PF1-33101 Finland

Systems are always designed and optimized based on full traffic load in the current literatures. However, practical systems are seldom operating at full load, even at peak traffic hours. Instead of maximizing system rate to achieve the full load, an optimal energy-efficient scheme to minimize the transmit power with required rates is investigated in this article. The considered scenario is a two-way relay channel using amplify-and-forward protocol of physical layer network coding, where two end nodes exchange messages via multiple relay nodes within two timeslots. A joint power allocation and relay selection scheme is designed to achieve the minimum transmit power. Through convex optimization theory, we firstly prove that single relay selection scheme is the most energy-efficient way for physical layer network coding. The closed-form expressions of power allocation are also given. Numerical simulations demonstrate the performance of the designed scheme as well as the comparison among different schemes.

关键词： energy-efficient two-way relay channel physical layer network coding power allocation relay selection rate constraints

Carbon nanotube integrated circuit technology:purification,assembly and integration

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International Journal of Extreme Manufacturing 2024年第3期6卷 120-138页

作者： Jianlei cui Fengqi Wei Xuesong mei State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China

As the manufacturing process of silicon-based integrated circuits(ICs)approaches its physical limit,the quantum effect of silicon-based field-effect transistors(FETs)has become increasingly *** the burgeoning carbon-based semiconductor technology has become one of the most disruptive technologies in the post-Moore *** one-dimensional nanomaterials,carbon nanotubes(CNTs)are far superior to silicon at the same technology nodes of FETs because of their excellent electrical transport and scaling properties,rendering them the most competitive material in the next-generation ICs ***,certain challenges impede the industrialization of CNTs,particularly in terms of material preparation,which significantly hinders the development of CNT-based *** on CNT-based ICs technology,this review summarizes its main technical status,development trends,existing challenges,and future development directions.

关键词： carbon nanotubes integrated circuits field-effect transistors post-Moore