In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to ...In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.展开更多
The 300 GHz band is located between millimeter wave and terahertz wave,and has abundant spectrum resources,which provides the possibility for realizing high-speed,large-capacity and low-latency wireless communication....The 300 GHz band is located between millimeter wave and terahertz wave,and has abundant spectrum resources,which provides the possibility for realizing high-speed,large-capacity and low-latency wireless communication.However,300 GHz long-distance wireless communication also faces many technical challenges,such as serious signal propagation loss,susceptibility to atmospheric environment,and high difficulty in antenna design and manufacturing.Starting from the overview of 300 GHz long-distance wireless communication,this paper reveals the channel estimation algorithm in 300 GHz long-distance wireless communication system,and analyzes the transmitter,receiver,channel coding and decoding technologies,hoping to provide some reference for the development and innovation of wireless communication technology.展开更多
This article presents a compact crab-shaped reconfigurable antenna(CSRA)designed for 5G sub-6 GHz wireless applications. The antenna achieves enhanced gain in a miniaturized form factor by incorporating a hexagonal sp...This article presents a compact crab-shaped reconfigurable antenna(CSRA)designed for 5G sub-6 GHz wireless applications. The antenna achieves enhanced gain in a miniaturized form factor by incorporating a hexagonal split-ring structure controlled via two radio frequency(RF) positive-intrinsicnegative(PIN) diodes(BAR64-02V). While the antenna is primarily designed to operate at 3.50 GHz for sub-6 GHz 5G applications, RF switching enables the CSRA to cover a broader frequency spectrum, including the S-band, X-band, and portions of the Ku-band. The proposed antenna offers several advantages: It is low-cost(fabricated on an FR-4 substrate), compact(achieving 64.07% size reduction compared to conventional designs), and features both frequency and gain reconfigurability through digitally controlled PIN diode switching. The reflection coefficients of the antenna, both without diodes and across all four switching states, were experimentally validated in the laboratory using a Keysight Field Fox microwave analyzer(N9916A, 14 GHz). The simulated radiation patterns and gain characteristics closely matched the measured values, demonstrating an excellent agreement. This study bridges the gap between traditional and next-generation antenna designs by offering a compact,cost-effective, and high-performance solution for multiband, reconfigurable wireless communication systems. The integration of double-split-ring resonators and dynamic reconfigurability makes the proposed antenna a strong candidate for various applications, including S-band and X-band systems, as well as the emerging lower 6G band(7.125 GHz–8.400 GHz).展开更多
With the rapid development and commercialization of wireless communications,the execution of OTA testing requires a tremendous amount of test time.Therefore,test time reduction is of great significance.The objective o...With the rapid development and commercialization of wireless communications,the execution of OTA testing requires a tremendous amount of test time.Therefore,test time reduction is of great significance.The objective of this article is to determine optimal measurement grids for SISO OTA testing of 5G Sub-6 GHz user equipments(UEs)in anechoic chamber with satisfactory accuracy and efficiency.The effect of different grid configurations on OTA performance is analyzed quantitatively using reference radiation patterns at different bands.These patterns are utilized to mimic the worst-case radiation patterns of 5G Sub-6 GHz UEs.Subsequently,the associated measurement uncertainty(MU)terms are quantitatively analyzed and determined based on statistical analysis.According to the comparison of calculated MUs,reduction of grid points from currentlyrequired 62(30/30,Δθ/Δϕ)to 26(45/45)could achieve roughly 60%test time reduction for Sub-6 GHz,while still maintaining an uncertainty level of≤0.25 dB.These values can be further reduced to 14(60/60)with 80%reduction for Sub-3 GHz.More importantly,the recommended grid configurations in this research are applicable to both TIS and TRP testing.展开更多
Recently H_(2)^(+)ion beam finds widespread use in many fields,and the demand of high-current H_(2)^(+)ion sources is urgent for numerous applications.However,there are currently almost no reported ion sources capable...Recently H_(2)^(+)ion beam finds widespread use in many fields,and the demand of high-current H_(2)^(+)ion sources is urgent for numerous applications.However,there are currently almost no reported ion sources capable of generating a directcurrent(DC)H_(2)^(+)beam with tens of mA current.In previous work at Peking University(PKU),H_(2)^(+)ion beams with a current of over 40 mA have been obtained in pulse mode,and a current of 16 mA was achieved in DC mode.In this paper,we report the generation of a DC H_(2)^(+)ion beam with a current of 22 mA extracted from an improved miniaturized microwave driven ion source(MMDIS).Beam analysis shows that the H_(2)^(+)fraction in the extracted beam is about 70%.The emittance of the mixed hydrogen beam is about 0.12π·mm·mrad.These results provide references for the applications of H_(2)^(+)beam and the design of H_(2)^(+)ion source.展开更多
基金supported in part by the National Natural Science Foundation of China under Grants 62325107,62341107,62261160650,and U23A20272in part by the Beijing Natural Science Foundation under Grant L222002.
文摘In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.
文摘The 300 GHz band is located between millimeter wave and terahertz wave,and has abundant spectrum resources,which provides the possibility for realizing high-speed,large-capacity and low-latency wireless communication.However,300 GHz long-distance wireless communication also faces many technical challenges,such as serious signal propagation loss,susceptibility to atmospheric environment,and high difficulty in antenna design and manufacturing.Starting from the overview of 300 GHz long-distance wireless communication,this paper reveals the channel estimation algorithm in 300 GHz long-distance wireless communication system,and analyzes the transmitter,receiver,channel coding and decoding technologies,hoping to provide some reference for the development and innovation of wireless communication technology.
文摘This article presents a compact crab-shaped reconfigurable antenna(CSRA)designed for 5G sub-6 GHz wireless applications. The antenna achieves enhanced gain in a miniaturized form factor by incorporating a hexagonal split-ring structure controlled via two radio frequency(RF) positive-intrinsicnegative(PIN) diodes(BAR64-02V). While the antenna is primarily designed to operate at 3.50 GHz for sub-6 GHz 5G applications, RF switching enables the CSRA to cover a broader frequency spectrum, including the S-band, X-band, and portions of the Ku-band. The proposed antenna offers several advantages: It is low-cost(fabricated on an FR-4 substrate), compact(achieving 64.07% size reduction compared to conventional designs), and features both frequency and gain reconfigurability through digitally controlled PIN diode switching. The reflection coefficients of the antenna, both without diodes and across all four switching states, were experimentally validated in the laboratory using a Keysight Field Fox microwave analyzer(N9916A, 14 GHz). The simulated radiation patterns and gain characteristics closely matched the measured values, demonstrating an excellent agreement. This study bridges the gap between traditional and next-generation antenna designs by offering a compact,cost-effective, and high-performance solution for multiband, reconfigurable wireless communication systems. The integration of double-split-ring resonators and dynamic reconfigurability makes the proposed antenna a strong candidate for various applications, including S-band and X-band systems, as well as the emerging lower 6G band(7.125 GHz–8.400 GHz).
基金supported by the Beijing Natural Science Foundation under Grant L253002.
文摘With the rapid development and commercialization of wireless communications,the execution of OTA testing requires a tremendous amount of test time.Therefore,test time reduction is of great significance.The objective of this article is to determine optimal measurement grids for SISO OTA testing of 5G Sub-6 GHz user equipments(UEs)in anechoic chamber with satisfactory accuracy and efficiency.The effect of different grid configurations on OTA performance is analyzed quantitatively using reference radiation patterns at different bands.These patterns are utilized to mimic the worst-case radiation patterns of 5G Sub-6 GHz UEs.Subsequently,the associated measurement uncertainty(MU)terms are quantitatively analyzed and determined based on statistical analysis.According to the comparison of calculated MUs,reduction of grid points from currentlyrequired 62(30/30,Δθ/Δϕ)to 26(45/45)could achieve roughly 60%test time reduction for Sub-6 GHz,while still maintaining an uncertainty level of≤0.25 dB.These values can be further reduced to 14(60/60)with 80%reduction for Sub-3 GHz.More importantly,the recommended grid configurations in this research are applicable to both TIS and TRP testing.
基金supported by the National Natural Science Foundation of China(Grant No.11975036)support from the State Key Laboratory of Nuclear Physics and Technology at PKU.
文摘Recently H_(2)^(+)ion beam finds widespread use in many fields,and the demand of high-current H_(2)^(+)ion sources is urgent for numerous applications.However,there are currently almost no reported ion sources capable of generating a directcurrent(DC)H_(2)^(+)beam with tens of mA current.In previous work at Peking University(PKU),H_(2)^(+)ion beams with a current of over 40 mA have been obtained in pulse mode,and a current of 16 mA was achieved in DC mode.In this paper,we report the generation of a DC H_(2)^(+)ion beam with a current of 22 mA extracted from an improved miniaturized microwave driven ion source(MMDIS).Beam analysis shows that the H_(2)^(+)fraction in the extracted beam is about 70%.The emittance of the mixed hydrogen beam is about 0.12π·mm·mrad.These results provide references for the applications of H_(2)^(+)beam and the design of H_(2)^(+)ion source.
