In this paper, the performance of a 60 GHz radio over fiber(Ro F) system with 4/16/64 quadrature amplitude modulation(QAM) orthogonal frequency division multiplexing(OFDM) downstream signals is studied. Delivery of 10...In this paper, the performance of a 60 GHz radio over fiber(Ro F) system with 4/16/64 quadrature amplitude modulation(QAM) orthogonal frequency division multiplexing(OFDM) downstream signals is studied. Delivery of 10 Gbit/s M-ary QAM(MQAM) OFDM signals through the 20-km-long single-mode fiber(SMF) is complicated in terms of intensity modulation and direct detection(IM/DD). Using self-homodyne method, the beating of two independent light waves generating the millimeter-wave at the photodetector can be down-converted to baseband in the electrical domain. Meanwhile, three kinds of sub-carrier arrangement schemes are compared and discussed, and the simulation results show that lower peak-to-average power ratio(PAPR) can be obtained adopting the adjacent scheme. At bit error rate(BER) of 10^(-3), the receiver sensitivity using 4QAM-OFDM sub-carrier signal is almost enhanced by 4 dB and 9 dB compared with those of 16 QAM-OFDM signal and 64 QAM-OFDM signal.展开更多
Coordinated multi-point transmission/reception(CoMP)was proposed currently as an effective technology to improve cell-edge throughput in next-generation wireless systems.Most of the existing work discussed clustering ...Coordinated multi-point transmission/reception(CoMP)was proposed currently as an effective technology to improve cell-edge throughput in next-generation wireless systems.Most of the existing work discussed clustering methods mostly to maximize the edge user throughput while neglecting the problem of energy efficiency,such as those algorithm clustering base stations(BSs)of better channel condition and BSs of worse channel condition together.In addition,BSs usually increase the transmit power to achieve higher throughput without any considering of interference caused to other users,that may result in energy waste.The authors focus on the throughput maximizing problem while fully considering energy saving problem in CoMP systems.A coefficient is defined to describe the fitness of clusters.Then a sub-carrier allocation algorithm with clustering method is put forward for CoMP downlink,which can save the transmit power of BS and increase the throughput.Furthermore a power allocation scheme is proposed based on non-cooperation game;in which the transmit power is decreased by BSs generally to reach the Nash equation(NE).Simulation shows that the proposed sub-carrier allocation scheme and power allocation algorithm are better than the existing ones on users’throughput while consumes much less energy.展开更多
正交频分多址接入(OFDMA,Orthogonal Frequency Division Multiple Access)已经成为3G演进策略(LTE,Long Term Evolution)及4G技术的主要多址接入方式.本文研究了现有的OFDMA的切换算法,分析了其存在的不足之处.本文针对OFDMA多址技术特...正交频分多址接入(OFDMA,Orthogonal Frequency Division Multiple Access)已经成为3G演进策略(LTE,Long Term Evolution)及4G技术的主要多址接入方式.本文研究了现有的OFDMA的切换算法,分析了其存在的不足之处.本文针对OFDMA多址技术特点,提出新型的OFDMA切换算法(SBA,Sub-carriers Bidirectional Arrayed handover).并通过仿真验证新型切换算法的性能.仿真结果表明,新型OFDMA切换算法保证了用户在切换过程中的信道质量(CIR,Carrier-Interference Ratio),减少了切换信道的数目,从而提高了OFDMA系统性能.展开更多
基金supported by the National Natural Science Foundation of China(No.61107064)the Bayu Scholars Founding,the Chongqing University Innovation Team Founding(No.KJTD201320)+3 种基金the Chongqing Science and Technology Commission Foundation(Nos.cstc2014jcyj A40046,cstc2016jcyj A1233 and cstc2016jcyj A0246)the Chongqing 2011 Collaborative Innovation Center Project(Chongqing Education Department(2016)No.40)the Chongqing Graduate Scientific Research Innovation Project(Nos.CYS15225 and CYS16225)the Science and Technology Special Funds in Wanzhou District
文摘In this paper, the performance of a 60 GHz radio over fiber(Ro F) system with 4/16/64 quadrature amplitude modulation(QAM) orthogonal frequency division multiplexing(OFDM) downstream signals is studied. Delivery of 10 Gbit/s M-ary QAM(MQAM) OFDM signals through the 20-km-long single-mode fiber(SMF) is complicated in terms of intensity modulation and direct detection(IM/DD). Using self-homodyne method, the beating of two independent light waves generating the millimeter-wave at the photodetector can be down-converted to baseband in the electrical domain. Meanwhile, three kinds of sub-carrier arrangement schemes are compared and discussed, and the simulation results show that lower peak-to-average power ratio(PAPR) can be obtained adopting the adjacent scheme. At bit error rate(BER) of 10^(-3), the receiver sensitivity using 4QAM-OFDM sub-carrier signal is almost enhanced by 4 dB and 9 dB compared with those of 16 QAM-OFDM signal and 64 QAM-OFDM signal.
基金supported by the National Hi-Tech Research and Development Program of China(2012AA01A508)
文摘Coordinated multi-point transmission/reception(CoMP)was proposed currently as an effective technology to improve cell-edge throughput in next-generation wireless systems.Most of the existing work discussed clustering methods mostly to maximize the edge user throughput while neglecting the problem of energy efficiency,such as those algorithm clustering base stations(BSs)of better channel condition and BSs of worse channel condition together.In addition,BSs usually increase the transmit power to achieve higher throughput without any considering of interference caused to other users,that may result in energy waste.The authors focus on the throughput maximizing problem while fully considering energy saving problem in CoMP systems.A coefficient is defined to describe the fitness of clusters.Then a sub-carrier allocation algorithm with clustering method is put forward for CoMP downlink,which can save the transmit power of BS and increase the throughput.Furthermore a power allocation scheme is proposed based on non-cooperation game;in which the transmit power is decreased by BSs generally to reach the Nash equation(NE).Simulation shows that the proposed sub-carrier allocation scheme and power allocation algorithm are better than the existing ones on users’throughput while consumes much less energy.
基金The Natural Science Foundation of Tianjin,China(No.15JCYBJC17000)the Science Foundation for the Youth of Hebei Province,China(Nos.F2014202036,F2015202331)the High-level Talents Program of Hebei Province,China(Nos.C2013001048,GCC2014011)
