Codebooks have been indispensable for wireless communication standard since the first release of the Long-Term Evolution in 2009.They offer an efficient way to acquire the channel state information(CSI)for multiple an...Codebooks have been indispensable for wireless communication standard since the first release of the Long-Term Evolution in 2009.They offer an efficient way to acquire the channel state information(CSI)for multiple antenna systems.Nowadays,a codebook is not limited to a set of pre-defined precoders,it refers to a CSI feedback framework,which is more and more sophisticated.In this paper,we review the codebooks in 5G New Radio(NR)standards.The codebook timeline and the evolution trend are shown.Each codebook is elaborated with its motivation,the corresponding feedback mechanism,and the format of the precoding matrix indicator.Some insights are given to help grasp the underlying reasons and intuitions of these codebooks.Finally,we point out some unresolved challenges of the codebooks for future evolution of the standards.In general,this paper provides a comprehensive review of the codebooks in 5G NR and aims to help researchers understand the CSI feedback schemes from a standard and industrial perspective.展开更多
How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to t...How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to the large number of antennas. To reduce the overwhelming pilot overhead, a hybrid orthogonal and non-orthogonal pilot distribution at the base station(BS),which is a generalization of the existing pilot distribution scheme,is proposed by exploiting the common sparsity of channel due to the compact antenna arrangement. Then the block sparsity for antennas with hybrid pilot distribution is derived respectively and can be used to obtain channel impulse response. By employing the theoretical analysis of block sparse recovery, the total coherence criterion is proposed to optimize the sensing matrix composed by orthogonal pilots. Due to the huge complexity of optimal pilot acquisition, a genetic algorithm based pilot allocation(GAPA) algorithm is proposed to acquire optimal pilot distribution locations with fast convergence. Furthermore, the Cramer Rao lower bound is derived for non-orthogonal pilot-based channel estimation and can be asymptotically approached by the prior support set, especially when the optimized pilot is employed.展开更多
To address the issue of information exposure arising from the openness of wireless channels,a point-to-point(P2P)communication system was constructed.Furthermore,a high-order secure encryption algorithm was incorporat...To address the issue of information exposure arising from the openness of wireless channels,a point-to-point(P2P)communication system was constructed.Furthermore,a high-order secure encryption algorithm was incorporated to encrypt the physical layer,thereby enhancing the system's security.Utilizing an open-source software defined radio(SDR)system,the system simplified the distributed competition mechanism within the IEEE802.11 protocol.It established a P2P communication network,implemented frequency division duplex(FDD)communication,and ensured efficient signal transmission.Based on the orthogonal frequency division multiplexing(OFDM)system model,the high-order secure encryption algorithm introduced in this paper incorporated a key management system that processed and concealed data within the high-order constellation diagram,thereby ensuring secure data transmission.Simulation and experimental results confirm that adding the algorithm significantly improves system safety without affecting key metrics such as bit error rate(BER)and peak-to-average power ratio(PAPR).展开更多
In view of the difficulty of obtaining downlink channel state information,partial reciprocity based channel covariance matrix(CCM)reconstruction has attracted a lot of attention in frequency division duplex(FDD)multi-...In view of the difficulty of obtaining downlink channel state information,partial reciprocity based channel covariance matrix(CCM)reconstruction has attracted a lot of attention in frequency division duplex(FDD)multi-antenna systems.Taking both the impact of CCM reconstruction on system performance and design complexity,we investigate an adaptive CCM reconstruction in this paper.Specifically,to effectively evaluate the validity of the reciprocity,we firstly analyze the characteristics of the partial reciprocity and define a reciprocity evaluation criterion.Then,we propose a partial antenna based angular power spectrum(APS)estimating algorithm to further reduce the complexity of the CCM reconstruction.Finally,simulation results demonstrate the superiority of our proposed schemes.展开更多
基金supported by the Fundamental Research Funds for the Central Universitiesthe National Natural Science Foundation of China under Grant 62071191
文摘Codebooks have been indispensable for wireless communication standard since the first release of the Long-Term Evolution in 2009.They offer an efficient way to acquire the channel state information(CSI)for multiple antenna systems.Nowadays,a codebook is not limited to a set of pre-defined precoders,it refers to a CSI feedback framework,which is more and more sophisticated.In this paper,we review the codebooks in 5G New Radio(NR)standards.The codebook timeline and the evolution trend are shown.Each codebook is elaborated with its motivation,the corresponding feedback mechanism,and the format of the precoding matrix indicator.Some insights are given to help grasp the underlying reasons and intuitions of these codebooks.Finally,we point out some unresolved challenges of the codebooks for future evolution of the standards.In general,this paper provides a comprehensive review of the codebooks in 5G NR and aims to help researchers understand the CSI feedback schemes from a standard and industrial perspective.
基金supported by the National Natural Science Foundation of China(61671176 61671173)the Fundamental Research Funds for the Center Universities(HIT.MKSTISP.2016 13)
文摘How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to the large number of antennas. To reduce the overwhelming pilot overhead, a hybrid orthogonal and non-orthogonal pilot distribution at the base station(BS),which is a generalization of the existing pilot distribution scheme,is proposed by exploiting the common sparsity of channel due to the compact antenna arrangement. Then the block sparsity for antennas with hybrid pilot distribution is derived respectively and can be used to obtain channel impulse response. By employing the theoretical analysis of block sparse recovery, the total coherence criterion is proposed to optimize the sensing matrix composed by orthogonal pilots. Due to the huge complexity of optimal pilot acquisition, a genetic algorithm based pilot allocation(GAPA) algorithm is proposed to acquire optimal pilot distribution locations with fast convergence. Furthermore, the Cramer Rao lower bound is derived for non-orthogonal pilot-based channel estimation and can be asymptotically approached by the prior support set, especially when the optimized pilot is employed.
基金supported by the National Key R&D Program of China(2022YFB2901100)。
文摘To address the issue of information exposure arising from the openness of wireless channels,a point-to-point(P2P)communication system was constructed.Furthermore,a high-order secure encryption algorithm was incorporated to encrypt the physical layer,thereby enhancing the system's security.Utilizing an open-source software defined radio(SDR)system,the system simplified the distributed competition mechanism within the IEEE802.11 protocol.It established a P2P communication network,implemented frequency division duplex(FDD)communication,and ensured efficient signal transmission.Based on the orthogonal frequency division multiplexing(OFDM)system model,the high-order secure encryption algorithm introduced in this paper incorporated a key management system that processed and concealed data within the high-order constellation diagram,thereby ensuring secure data transmission.Simulation and experimental results confirm that adding the algorithm significantly improves system safety without affecting key metrics such as bit error rate(BER)and peak-to-average power ratio(PAPR).
基金supported in part by the Shaanxi Provincial Key Research and Development Programs(2023-ZDLGY-33,2022ZDLGY05-03,2022ZDLGY05-04,2021ZDLGY04-08).
文摘In view of the difficulty of obtaining downlink channel state information,partial reciprocity based channel covariance matrix(CCM)reconstruction has attracted a lot of attention in frequency division duplex(FDD)multi-antenna systems.Taking both the impact of CCM reconstruction on system performance and design complexity,we investigate an adaptive CCM reconstruction in this paper.Specifically,to effectively evaluate the validity of the reciprocity,we firstly analyze the characteristics of the partial reciprocity and define a reciprocity evaluation criterion.Then,we propose a partial antenna based angular power spectrum(APS)estimating algorithm to further reduce the complexity of the CCM reconstruction.Finally,simulation results demonstrate the superiority of our proposed schemes.
