In modern wireless communication systems,the signal-to-noise ratio(SNR)is one of the most important performance indicators.When the other radio frequency(RF)performance of the components is well designed,passive inter...In modern wireless communication systems,the signal-to-noise ratio(SNR)is one of the most important performance indicators.When the other radio frequency(RF)performance of the components is well designed,passive intermodulation(PIM)interference may become an important factor limiting the system’s SNR.Whether it is a base station,an indoor distributed antenna system,or a satellite system,there are stringent PIM level requirements to minimize interference and enhance network capacity in multicarrier networks.Especially for systems of high power and wide bandwidth such as 5G wireless communication,PIM interference is even more serious.Due to the complexity and uncertainty of PIM,measurement is the most important means to study and evaluate the PIM performance of wireless communication systems.In this review,the current main PIM measurement methods recommended by International Electrotechnical Commission(IEC)and other standard organizations are introduced,and several key challenges in PIM measurement and their solutions(including the design of PIM tester,the location of the PIM sources,the design of compact PIM anechoic chambers,and the evaluation methods of PIM anechoic chambers)are highlighted.These challenges are of great significance to solve PIM problems that may arise during device characterization and verification in real wireless communication systems.展开更多
Over-the-air(OTA)testing is an industry standard practice for evaluating transceiver performance in wireless devices.For the fifth generation(5G)and beyond wireless systems with high integration,OTA testing is probabl...Over-the-air(OTA)testing is an industry standard practice for evaluating transceiver performance in wireless devices.For the fifth generation(5G)and beyond wireless systems with high integration,OTA testing is probably the only reliable method to accurately measure the transceiver performance,suitable for certification as well as for providing feedback for design verification and optimization.Further,multiple-input multiple-output(MIMO)technology is extensively applied for stable connection,high throughput rate,and low latency.In this paper,we provide an overview of the three main methods for evaluating the MIMO OTA performance,namely,the multiprobe anechoic chamber(MPAC)method,the reverberation chamber plus channel emulator(RC+CE)method,and the radiated two-stage(RTS)method,with the aim of providing a useful guideline for developing effective wireless performance testing in future 5G-and-beyond wireless systems.展开更多
With a given communication protocol,performance optimization of a multiple-input multipleoutput(MIMO)wireless system mainly lies on the design of the radio frequency(RF)front end.Currently,the optimization is mainly a...With a given communication protocol,performance optimization of a multiple-input multipleoutput(MIMO)wireless system mainly lies on the design of the radio frequency(RF)front end.Currently,the optimization is mainly achieved based on experiences,such as promoting the multiple antenna gains and reducing their correlations.This experience-based method works to a certain extent,but is inefficient since the final performance impact by each sub-system is not quantified.The challenge lies on how to find the most limiting factor that restricts the overall communication throughput.This paper presents an analytical model for throughput calculations of 2×2 MIMO wireless system,which is built on a first step of maximum rate calculated under the chosen protocol and channel,followed by a second step of throughput baseline measurement,and continued with the third step of throughput calculations of the overall system according to the actual settings of subsystems.The model can provide a detailed diagnostic report of each RF factor,which will directly point out the imperfections and make the troubleshooting and debugging much more effective.Besides,throughput is analyzed in a mathematical approach that allows the performance more predictable during the design phase.展开更多
Multi-band signal propagation and processing play an important role in quantum communications and quantum computing.In recent years,optical nonreciprocal devices such as an optical isolator and circulator are proposed...Multi-band signal propagation and processing play an important role in quantum communications and quantum computing.In recent years,optical nonreciprocal devices such as an optical isolator and circulator are proposed via various configurations of atoms,metamaterials,nonlinear waveguides,etc.In this work,we investigate all-optical controlled nonreciprocity of multi-band optical signals in thermal atomic systems.Via introducing multiple strong coupling fields,nonreciprocal propagation of the probe field can happen at some separated frequency bands,which results from combination of the electromagnetically induced transparency(EIT) effect and atomic thermal motion.In the proposed configuration,the frequency shift resulting from atomic thermal motion takes converse effect on the probe field in the two opposite directions.In this way,the probe field can propagate almost transparently within some frequency bands of EIT windows in the opposite direction of the coupling fields.However,it is well blocked within the considered frequency region in the same direction of the coupling fields because of destruction of the EIT.Such selectable optical nonreciprocity and isolation for discrete signals may be greatly useful in controlling signal transmission and realizing selective optical isolation functions.展开更多
文摘In modern wireless communication systems,the signal-to-noise ratio(SNR)is one of the most important performance indicators.When the other radio frequency(RF)performance of the components is well designed,passive intermodulation(PIM)interference may become an important factor limiting the system’s SNR.Whether it is a base station,an indoor distributed antenna system,or a satellite system,there are stringent PIM level requirements to minimize interference and enhance network capacity in multicarrier networks.Especially for systems of high power and wide bandwidth such as 5G wireless communication,PIM interference is even more serious.Due to the complexity and uncertainty of PIM,measurement is the most important means to study and evaluate the PIM performance of wireless communication systems.In this review,the current main PIM measurement methods recommended by International Electrotechnical Commission(IEC)and other standard organizations are introduced,and several key challenges in PIM measurement and their solutions(including the design of PIM tester,the location of the PIM sources,the design of compact PIM anechoic chambers,and the evaluation methods of PIM anechoic chambers)are highlighted.These challenges are of great significance to solve PIM problems that may arise during device characterization and verification in real wireless communication systems.
基金Project supported by the National Natural Science Foundation of China(No.61671203)。
文摘Over-the-air(OTA)testing is an industry standard practice for evaluating transceiver performance in wireless devices.For the fifth generation(5G)and beyond wireless systems with high integration,OTA testing is probably the only reliable method to accurately measure the transceiver performance,suitable for certification as well as for providing feedback for design verification and optimization.Further,multiple-input multiple-output(MIMO)technology is extensively applied for stable connection,high throughput rate,and low latency.In this paper,we provide an overview of the three main methods for evaluating the MIMO OTA performance,namely,the multiprobe anechoic chamber(MPAC)method,the reverberation chamber plus channel emulator(RC+CE)method,and the radiated two-stage(RTS)method,with the aim of providing a useful guideline for developing effective wireless performance testing in future 5G-and-beyond wireless systems.
基金This work was supported in part by Chinese Ministry of Education—China Mobile Research Foundation under Grant MCM 20150101in part by National Natural Science Foundation of China under Grant 61671203.
文摘With a given communication protocol,performance optimization of a multiple-input multipleoutput(MIMO)wireless system mainly lies on the design of the radio frequency(RF)front end.Currently,the optimization is mainly achieved based on experiences,such as promoting the multiple antenna gains and reducing their correlations.This experience-based method works to a certain extent,but is inefficient since the final performance impact by each sub-system is not quantified.The challenge lies on how to find the most limiting factor that restricts the overall communication throughput.This paper presents an analytical model for throughput calculations of 2×2 MIMO wireless system,which is built on a first step of maximum rate calculated under the chosen protocol and channel,followed by a second step of throughput baseline measurement,and continued with the third step of throughput calculations of the overall system according to the actual settings of subsystems.The model can provide a detailed diagnostic report of each RF factor,which will directly point out the imperfections and make the troubleshooting and debugging much more effective.Besides,throughput is analyzed in a mathematical approach that allows the performance more predictable during the design phase.
基金supported by the National Natural Science Foundation of China (Nos. 11874146, 11974109, and 12034007)
文摘Multi-band signal propagation and processing play an important role in quantum communications and quantum computing.In recent years,optical nonreciprocal devices such as an optical isolator and circulator are proposed via various configurations of atoms,metamaterials,nonlinear waveguides,etc.In this work,we investigate all-optical controlled nonreciprocity of multi-band optical signals in thermal atomic systems.Via introducing multiple strong coupling fields,nonreciprocal propagation of the probe field can happen at some separated frequency bands,which results from combination of the electromagnetically induced transparency(EIT) effect and atomic thermal motion.In the proposed configuration,the frequency shift resulting from atomic thermal motion takes converse effect on the probe field in the two opposite directions.In this way,the probe field can propagate almost transparently within some frequency bands of EIT windows in the opposite direction of the coupling fields.However,it is well blocked within the considered frequency region in the same direction of the coupling fields because of destruction of the EIT.Such selectable optical nonreciprocity and isolation for discrete signals may be greatly useful in controlling signal transmission and realizing selective optical isolation functions.
