Narrowband Internet of Things(NB-IoT)has been proposed to support deep coverage(in building)and extended geographic coverage of IoT.In this paper,a power control scheme for maximizing energy efficiency(EE)of narrowban...Narrowband Internet of Things(NB-IoT)has been proposed to support deep coverage(in building)and extended geographic coverage of IoT.In this paper,a power control scheme for maximizing energy efficiency(EE)of narrowband physical uplink shared channel(NPUSCH)with the guard band is proposed.First,we form the optimization problem based on the signal model with the interferences of narrowband physical random access channel(NPRACH)which are caused by the non-orthogonality of NPUSCH and NPRACH.Then,a method of reserving guard bands is proposed to reduce these interferences.Based on it,an efficient iterative power control algorithm is derived to solve the optimization problem,which adopts fractional programming.Numerical simulation results show that NPUSCH with the guard band has better performance in EE than that without the guard band.展开更多
This paper presents a high efficiency Doherty power amplifier suitable for TV band applications. A class AB power amplifier is firstly implemented using a commercial GaN HEMT from Cree Incorporation, achieving a high ...This paper presents a high efficiency Doherty power amplifier suitable for TV band applications. A class AB power amplifier is firstly implemented using a commercial GaN HEMT from Cree Incorporation, achieving a high power-added-efficiency of 77.78% and a 40.593 dBm output power with an associated gain of 21.65 dB. The Doherty amplifier has then been designed following the previous class AB scheme for the main amplifier and a class C scheme for the peak one. This amplifier attained a high power-added-efficiency of 81.94%, a 42.77 dBm output power, an associated gain of 21.32 dB, and an operating frequency bandwidth between 550 and 1000 MHz (58.06% fractional bandwidth) which made it suitable for TV band applications.展开更多
Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, m...Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, multilevel modulation, such as PDM 16 quadrature-amplitude modulation （16-QAM）, is much more sensitive to intrachannel noise and interchannel linear crosstalk caused by N-WDM. We experimentally generate and transmit a 6 x 128 Gbit/s N-WDM PDM 16-QAM signal over 1200 km single-mode fiber （SMF）-28 with amplification provided by an erbium-doped fiber amplifier （EDFA） only. The net SE is 7.47 bit/s/Hz, which to the best of our knowledge is the highest SE for a signal with a bit rate beyond 100 Gbit/s using the PDM 16-QAM. Such SE was achieved by DSP pre-equalization of transmitter-side impairments and DSP post-equalization of channel and receiver-side impairments. Nyquist-band can be used in pre-equalization to enhance the tolerance of PDM 16-QAM to aggressive spectral shaping. The bit-error ratio （BER） for each of the 6 channels is smaller than the forward error correction （FEC） limit of 3.8 × 10-3 after 1200 km SMF-28 transmission.展开更多
With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recen...With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density(W_(rec)).Nevertheless,the dielectric loss also increases as the external electric field increases,which will generate much dissipated energy and raise the temperature of ceramic capacitors.Thus,an effective strategy is proposed to enhance the energy storage efficiency(η)via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na_(0.5)K_(0.5))-NbO_(3)-0.1Bi(Zn_(2/3)(Nb_(x)Ta_(1−x))1/3)O_(3) ceramics.On the one hand,the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short−range polar nanoregions(PNRs),resulting in the highη.On the other hand,the introduction of Ta ions could boost the intrinsic band energy gap and thus improve the Eb.As a result,high Wrec of 3.29 J/cm^(3) and ultrahighηof 90.1%at the high external electric field of 310 kV/cm are achieved in x=0.5 sample.These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.展开更多
电源网络S参数与芯片电源模型(Chip Power Module,CPM)级联可实现电源时域噪声仿真,完成电源完整性设计签核。当下部分仿真工具在AC阻抗优化过程中导出的S参数存在低频段无法覆盖的问题,影响时域纹波仿真精度,如果重新对S参数进行提取,...电源网络S参数与芯片电源模型(Chip Power Module,CPM)级联可实现电源时域噪声仿真,完成电源完整性设计签核。当下部分仿真工具在AC阻抗优化过程中导出的S参数存在低频段无法覆盖的问题,影响时域纹波仿真精度,如果重新对S参数进行提取,又会增加仿真时间降低仿真效率。针对AC阻抗优化过程中导出的S参数无法覆盖低频段的问题,提出了一种电源网络S参数低频段拓展方法,结合电压调节模块(Voltage Regulator Module,VRM)的R-L模型,推导出低频段的S参数可以借用抽取的S参数中最低频点处的S参数实现低频段S参数的拓展。仿真和实验结果表明,通过对低频段S参数进行拓展,电源时域纹波噪声仿真的精度提升31%。同时,低频段的S参数直接借用已抽取的S参数中低频点的数值无须重复提取,在8 GB内存的配置下,仿真时间节约14%左右,提高了仿真效率。展开更多
基金supported by the National Natural Science Foundation of China under Grant No.61501056National Science and Technology Major Project of China under Grant No.2016ZX03001012ZTE IndustryAcademia-Research Cooperation Funds
文摘Narrowband Internet of Things(NB-IoT)has been proposed to support deep coverage(in building)and extended geographic coverage of IoT.In this paper,a power control scheme for maximizing energy efficiency(EE)of narrowband physical uplink shared channel(NPUSCH)with the guard band is proposed.First,we form the optimization problem based on the signal model with the interferences of narrowband physical random access channel(NPRACH)which are caused by the non-orthogonality of NPUSCH and NPRACH.Then,a method of reserving guard bands is proposed to reduce these interferences.Based on it,an efficient iterative power control algorithm is derived to solve the optimization problem,which adopts fractional programming.Numerical simulation results show that NPUSCH with the guard band has better performance in EE than that without the guard band.
文摘This paper presents a high efficiency Doherty power amplifier suitable for TV band applications. A class AB power amplifier is firstly implemented using a commercial GaN HEMT from Cree Incorporation, achieving a high power-added-efficiency of 77.78% and a 40.593 dBm output power with an associated gain of 21.65 dB. The Doherty amplifier has then been designed following the previous class AB scheme for the main amplifier and a class C scheme for the peak one. This amplifier attained a high power-added-efficiency of 81.94%, a 42.77 dBm output power, an associated gain of 21.32 dB, and an operating frequency bandwidth between 550 and 1000 MHz (58.06% fractional bandwidth) which made it suitable for TV band applications.
文摘Nyquist wavelength-division multiplexing （N-WDM） allows high spectral efficiency （SE） in long-haul transmission systems. Compared to polarization-division multiplexing quadrature phase-shift keying （PDM-QPSK）, multilevel modulation, such as PDM 16 quadrature-amplitude modulation （16-QAM）, is much more sensitive to intrachannel noise and interchannel linear crosstalk caused by N-WDM. We experimentally generate and transmit a 6 x 128 Gbit/s N-WDM PDM 16-QAM signal over 1200 km single-mode fiber （SMF）-28 with amplification provided by an erbium-doped fiber amplifier （EDFA） only. The net SE is 7.47 bit/s/Hz, which to the best of our knowledge is the highest SE for a signal with a bit rate beyond 100 Gbit/s using the PDM 16-QAM. Such SE was achieved by DSP pre-equalization of transmitter-side impairments and DSP post-equalization of channel and receiver-side impairments. Nyquist-band can be used in pre-equalization to enhance the tolerance of PDM 16-QAM to aggressive spectral shaping. The bit-error ratio （BER） for each of the 6 channels is smaller than the forward error correction （FEC） limit of 3.8 × 10-3 after 1200 km SMF-28 transmission.
基金supported by the National Natural Science Foundation of China(Grant No.52072150)the Young Elite Scientists Sponsorship Program of the Chinese Academy of Space Technology(CAST)and Open Foundation of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices(EFMD2021002Z).
文摘With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density(W_(rec)).Nevertheless,the dielectric loss also increases as the external electric field increases,which will generate much dissipated energy and raise the temperature of ceramic capacitors.Thus,an effective strategy is proposed to enhance the energy storage efficiency(η)via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na_(0.5)K_(0.5))-NbO_(3)-0.1Bi(Zn_(2/3)(Nb_(x)Ta_(1−x))1/3)O_(3) ceramics.On the one hand,the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short−range polar nanoregions(PNRs),resulting in the highη.On the other hand,the introduction of Ta ions could boost the intrinsic band energy gap and thus improve the Eb.As a result,high Wrec of 3.29 J/cm^(3) and ultrahighηof 90.1%at the high external electric field of 310 kV/cm are achieved in x=0.5 sample.These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.
