The current High-Speed Railway(HSR)communications increasingly fail to satisfy the massive access services of numerous user equipment brought by the increasing number of people traveling by HSRs.To this end,this paper...The current High-Speed Railway(HSR)communications increasingly fail to satisfy the massive access services of numerous user equipment brought by the increasing number of people traveling by HSRs.To this end,this paper investigates millimeter-Wave(mmWave)extra-large scale(XL)-MIMO-based massive Internet-of-Things(loT)access in near-field HSR communications,and proposes a block simultaneous orthogonal matching pursuit(B-SOMP)-based Active User Detection(AUD)and Channel Estimation(CE)scheme by exploiting the spatial block sparsity of the XLMIMO-based massive access channels.Specifically,we first model the uplink mmWave XL-MIMO channels,which exhibit the near-field propagation characteristics of electromagnetic signals and the spatial non-stationarity of mmWave XL-MIMO arrays.By exploiting the spatial block sparsity and common frequency-domain sparsity pattern of massive access channels,the joint AUD and CE problem can be then formulated as a Multiple Measurement Vectors Compressive Sensing(MIMV-CS)problem.Based on the designed sensing matrix,a B-SOMP algorithm is proposed to achieve joint AUD and CE.Finally,simulation results show that the proposed solution can obtain a better AUD and CE performance than the conventional CS-based scheme for massive IoT access in near-field HSR communications.展开更多
In the vision of"smart rail mobility",a seamless high-data-rate wireless connectivity with up to dozens of GHz bandwidth will be required.This forms a strong motivation for exploring the underutilized millim...In the vision of"smart rail mobility",a seamless high-data-rate wireless connectivity with up to dozens of GHz bandwidth will be required.This forms a strong motivation for exploring the underutilized millimeter wave(mmWave)and Terahertz(THz)bands.In this paper,we identify the main challenges and present the state-of-the-art solutions towards the realization of smart rail mobility.In order to cope with the challenge of involving the railway features in the channel models,we define and reconstruct the complete version and the concise version of the reference scenario modules for mmWave and THz railway channels.Simulations in the complete version of the scenarios reflect the influence of railway objects in detail;based on raytracing simulations in the concise version of the scenarios,two mmWave railway channel models are established and validated by measurements.Moreover,in order to tackle the challenge of heavy computing workload,we develop an open-access high performance ray-tracing platform—CloudRT.Last but not least,the challenges raised by the mmWave directional network under high mobility are overcome by our solutions concerning the handover scheme,random access procedure,and beamforming strategies.By integrating the key enabling technologies presented in this paper,we prototype the mobile hotspot network(MHN)system which realizes 1.25 Gbps downlink data throughput in a subway line with the train speed of 80 km/h.Future directions towards the full version of the smart rail mobility are pointed out as well.展开更多
In the new era of railways, infrastructure, trains and travelers will be interconnected. In order to realize a seamless high-data rate wireless connectivity, up to dozens of GHz bandwidth is required. This motivates t...In the new era of railways, infrastructure, trains and travelers will be interconnected. In order to realize a seamless high-data rate wireless connectivity, up to dozens of GHz bandwidth is required. This motivates the exploration of the underutilized millimeter wave （mmWave） as well as the largely unexplored THz band. In this paper, we first identify relevant communication scenarios for railway applications. Then the specific challenges and estimates of the bandwidth requirements for high-data rate railway connec-tivity in these communication scenarios are described. Finally, we outline the major challenges on propagation channel modeling and provide a technical route for further studies.展开更多
基金supported in part by the Natural Science Foundation of China(NSFC)under Grant 62071044 and Grant 62088101in part by the Shandong Province Natural Science Foundation under Grant ZR2022YQ62in part by the Beijing Nova Program.
文摘The current High-Speed Railway(HSR)communications increasingly fail to satisfy the massive access services of numerous user equipment brought by the increasing number of people traveling by HSRs.To this end,this paper investigates millimeter-Wave(mmWave)extra-large scale(XL)-MIMO-based massive Internet-of-Things(loT)access in near-field HSR communications,and proposes a block simultaneous orthogonal matching pursuit(B-SOMP)-based Active User Detection(AUD)and Channel Estimation(CE)scheme by exploiting the spatial block sparsity of the XLMIMO-based massive access channels.Specifically,we first model the uplink mmWave XL-MIMO channels,which exhibit the near-field propagation characteristics of electromagnetic signals and the spatial non-stationarity of mmWave XL-MIMO arrays.By exploiting the spatial block sparsity and common frequency-domain sparsity pattern of massive access channels,the joint AUD and CE problem can be then formulated as a Multiple Measurement Vectors Compressive Sensing(MIMV-CS)problem.Based on the designed sensing matrix,a B-SOMP algorithm is proposed to achieve joint AUD and CE.Finally,simulation results show that the proposed solution can obtain a better AUD and CE performance than the conventional CS-based scheme for massive IoT access in near-field HSR communications.
基金supported by the National Natural Science Foundation of China(Grant Nos.61771036,U1834210,61901029,and 61725101).
文摘In the vision of"smart rail mobility",a seamless high-data-rate wireless connectivity with up to dozens of GHz bandwidth will be required.This forms a strong motivation for exploring the underutilized millimeter wave(mmWave)and Terahertz(THz)bands.In this paper,we identify the main challenges and present the state-of-the-art solutions towards the realization of smart rail mobility.In order to cope with the challenge of involving the railway features in the channel models,we define and reconstruct the complete version and the concise version of the reference scenario modules for mmWave and THz railway channels.Simulations in the complete version of the scenarios reflect the influence of railway objects in detail;based on raytracing simulations in the concise version of the scenarios,two mmWave railway channel models are established and validated by measurements.Moreover,in order to tackle the challenge of heavy computing workload,we develop an open-access high performance ray-tracing platform—CloudRT.Last but not least,the challenges raised by the mmWave directional network under high mobility are overcome by our solutions concerning the handover scheme,random access procedure,and beamforming strategies.By integrating the key enabling technologies presented in this paper,we prototype the mobile hotspot network(MHN)system which realizes 1.25 Gbps downlink data throughput in a subway line with the train speed of 80 km/h.Future directions towards the full version of the smart rail mobility are pointed out as well.
文摘In the new era of railways, infrastructure, trains and travelers will be interconnected. In order to realize a seamless high-data rate wireless connectivity, up to dozens of GHz bandwidth is required. This motivates the exploration of the underutilized millimeter wave （mmWave） as well as the largely unexplored THz band. In this paper, we first identify relevant communication scenarios for railway applications. Then the specific challenges and estimates of the bandwidth requirements for high-data rate railway connec-tivity in these communication scenarios are described. Finally, we outline the major challenges on propagation channel modeling and provide a technical route for further studies.
