In order to improve the broadcast reception rates of beacon messages in vehicle ad-hoc networks,a conclusion that the relationship between collision probability and minimum contention window size and the relationship ...In order to improve the broadcast reception rates of beacon messages in vehicle ad-hoc networks,a conclusion that the relationship between collision probability and minimum contention window size and the relationship between expiration probability and minimum window size was reached by building a Markov model. According to this conclusion, a back-off algorithm based on adjusting the size of minimum contention window called CEB is proposed, and this algorithm is on the basis of the differential size between the number of expiration beacons and preset threshold. Simulations were done to compare the performance of CEB with that of RBEB and BEB, and the results show that the performance of the new proposed algorithm is better than that of RBEB and BEB.展开更多
The present paper proposes an optimization design method for the Doherty output matching network(OMN)using impedance–phase hybrid objective function constraints,which possesses the capability of enhancing the efficie...The present paper proposes an optimization design method for the Doherty output matching network(OMN)using impedance–phase hybrid objective function constraints,which possesses the capability of enhancing the efficiency consistency of the Doherty power amplifier(DPA)using integrated enhancing reactance(IER)during the back-off power(BOP)range.By calculating the desired reactance for an extended BOP range and combining it with the two-impedance matching method,the S-parameters of the OMN are obtained.Meanwhile,the impedance and phase constraints of the OMN are proposed to narrow the distribution range of the IER.Furthermore,a fragmenttype structure is employed in the OMN optimization so as to enhance the flexibility of the circuit optimization design.To validate the proposed method,a 1.7–2.5 GHz symmetric DPA with a large BOP range was designed and fabricated.Measurement results demonstrate that across the entire operating frequency band,the saturated output power is>44 dBm,and the efficiency ranges from 45%to 55%at a 9-dB BOP.展开更多
A novel method is proposed to extend the output power back-off(OPBO)range of the Doherty power amplifier(DPA).This study reveals that the OPBO range of the DPA can be extended by tuning the output impedance of the pea...A novel method is proposed to extend the output power back-off(OPBO)range of the Doherty power amplifier(DPA).This study reveals that the OPBO range of the DPA can be extended by tuning the output impedance of the peaking stage away from infinity and changing the phase delay of the output matching network of the carrier power amplifier.Based on this theory,a large-OPBO-range high-efficiency asymmetrical DPA working band from 1.55 to 2.2 GHz(35%relative bandwidth)is designed to verify the proposed method.Experimental results show that the DPA operates from 1.6 to 2.1 GHz.The range of the measured efficiency is 42.2%–52.1%in the OPBO state and 47%–62.7%in the saturation state.The OPBO range is 11.1–13.2 dB.展开更多
基金supported by National Basic Research Program of China (2013CB329005)National Natural Science Foundation of China (61302100, 61201162, 61471203)+1 种基金Basic Research Program of Jiangsu Province (BK2011027)Specialized Research Fund for the Doctoral Program of Higher Education (20133223120002)
文摘In order to improve the broadcast reception rates of beacon messages in vehicle ad-hoc networks,a conclusion that the relationship between collision probability and minimum contention window size and the relationship between expiration probability and minimum window size was reached by building a Markov model. According to this conclusion, a back-off algorithm based on adjusting the size of minimum contention window called CEB is proposed, and this algorithm is on the basis of the differential size between the number of expiration beacons and preset threshold. Simulations were done to compare the performance of CEB with that of RBEB and BEB, and the results show that the performance of the new proposed algorithm is better than that of RBEB and BEB.
基金supported by the National Natural Science Foundation of China(Nos.62171204,62001192,and 62171129)。
文摘The present paper proposes an optimization design method for the Doherty output matching network(OMN)using impedance–phase hybrid objective function constraints,which possesses the capability of enhancing the efficiency consistency of the Doherty power amplifier(DPA)using integrated enhancing reactance(IER)during the back-off power(BOP)range.By calculating the desired reactance for an extended BOP range and combining it with the two-impedance matching method,the S-parameters of the OMN are obtained.Meanwhile,the impedance and phase constraints of the OMN are proposed to narrow the distribution range of the IER.Furthermore,a fragmenttype structure is employed in the OMN optimization so as to enhance the flexibility of the circuit optimization design.To validate the proposed method,a 1.7–2.5 GHz symmetric DPA with a large BOP range was designed and fabricated.Measurement results demonstrate that across the entire operating frequency band,the saturated output power is>44 dBm,and the efficiency ranges from 45%to 55%at a 9-dB BOP.
基金Project supported by the National Natural Science Founda-tion of China(Nos.62001061 and 62171068)the Science and Technology Research Program of Chongqing Municipal Educa-tion Commission(No.KJQN201900621)the Natural Science Foundation of Chongqing,China(No.cstc2020jcyj-msxmX0129)。
文摘A novel method is proposed to extend the output power back-off(OPBO)range of the Doherty power amplifier(DPA).This study reveals that the OPBO range of the DPA can be extended by tuning the output impedance of the peaking stage away from infinity and changing the phase delay of the output matching network of the carrier power amplifier.Based on this theory,a large-OPBO-range high-efficiency asymmetrical DPA working band from 1.55 to 2.2 GHz(35%relative bandwidth)is designed to verify the proposed method.Experimental results show that the DPA operates from 1.6 to 2.1 GHz.The range of the measured efficiency is 42.2%–52.1%in the OPBO state and 47%–62.7%in the saturation state.The OPBO range is 11.1–13.2 dB.
文摘该文针对椭圆球面波(Prolate Spheroidal Wave Function,PSWF)时域正交调制信号峰均功率比过高,易受功率放大器非线性影响,造成信号失真,导致系统解调性能下降的问题,提出一种基于μ律压缩的自适应峰均比抑制方法。该方法能够根据输入信号自适应调节压缩参数,有效压缩信号峰值,降低PSWF调制信号峰均功率比(Peak-to-Average Power Ratio,PAPR),同时保证压缩前后信号平均功率不变。理论论证和仿真结果表明,该方法能够有效抑制PSWF调制信号PAPR,当压缩参数m为1且互补累计分布函数CCDF为410-时,压缩后调制信号与原调制信号相比PAPR降低约2.1 d B;有效改善经过功放后调制信号功率谱和系统在高斯白噪声信道下的误码性能。
