In this paper,a new idea based on pseudolite signal acquisition method aiming to mitigate the near-far effect problemin the satellite positioning is proposed.After analyzing the signal capture principle based on coher...In this paper,a new idea based on pseudolite signal acquisition method aiming to mitigate the near-far effect problemin the satellite positioning is proposed.After analyzing the signal capture principle based on coherent integration and non-coherentaccumulation,the cross-correlation interference of strong and weak signals is eliminated by means of normalization of reconstructedstrong signal and judgement of the characteristics of the peak value,which can avoid the near-far effect of the pseudolitesignal.It can also estimate all the strong signals without any additional hardware.By building an indoor pseudolite positioningsystem,the capture performance becomes better based on improved acquisition algorithm compared with that based on thenon-coherent accumulation after coherent integration algorithm.The near-far effect is restrained effectively and the probabilityof weak signal detection is increased by25%.展开更多
Crosstalk is the main degrading factor in Digital Subscriber Line (DSL) systems which are the result of electromagnetic coupling between two adjacent twisted pairs in a cable. Very-high bit-rate Digital Subscriber Lin...Crosstalk is the main degrading factor in Digital Subscriber Line (DSL) systems which are the result of electromagnetic coupling between two adjacent twisted pairs in a cable. Very-high bit-rate Digital Subscriber Line (VDSL) systems which use higher frequencies for data transmission than the other DSL systems, this effect is more considerable in Bit Error Rate (BER) degradation. This paper considers a complete adaptive iterative water-filling (IWF) algorithm for Resolving Upstream Near-Far Problem in VDSL Systems. The new distributed dynamic spectrum management algorithm is proposed, which improve achievable bit rate of iterative water-filling algorithm. The paper proffers a new power back-off strategy of the spectral mask at the near-end users, in order to protect the far-end users. Simulation of the proposed algorithm indicates that the bit rate is increased considerably rather the IWF and adaptive water-filling (AIWF) algorithms by keeping their low complexity. Furthermore, by adding the number of users in network, the new algorithm achieves performance gains over the AIWF, completely adaptive.展开更多
The decorrelating detector for direct-sequence code-division multiple access (DS-CDMA) can afford good data estimate because it does not need to know many parameters of the received signal. However, it shows great per...The decorrelating detector for direct-sequence code-division multiple access (DS-CDMA) can afford good data estimate because it does not need to know many parameters of the received signal. However, it shows great performance deprivation when the background noise is high. On the other hand, partial parallel interference canceller (PPIC) has the potential to combat the near-far problem and have much lower computation complexity. But its performance depends on the initial data estimate. An improved PPIC scheme is proposed in this paper to combat the near-far problem. It utilizes the advantages of the two detectors by combining them. The focus of this paper is on the BER performance and the near-far resistance capability of the proposed scheme. Computer simulations demonstrate that the proposed detector has good BER performance and near-far resistance capability.展开更多
Recently,holographic multiple-input multiple-output(HMIMO)has motivated its potential use to support high-capacity data transmission with spatially quasi-continuous apertures.As a practical instance of HMIMO,reconfigu...Recently,holographic multiple-input multiple-output(HMIMO)has motivated its potential use to support high-capacity data transmission with spatially quasi-continuous apertures.As a practical instance of HMIMO,reconfigurable refractive surfaces(RRSs)equipped with numerous metamaterial elements are utilized as antennas by refracting incident signals from signal sources.In this paper,we investigate a multi-user communication system with an RRS deployed as the base station(BS)’s transmit antenna.To mitigate the high overhead of accurate channel state information(CSI)acquisition,the codebook design and beam training are employed to perform beamforming.Given the large scale of RRS,users are likely to be randomly distributed in both the near and far fields around the BS,which is unknown in advance.By considering radiation characteristics in both fields,a near-far field codebook is designed to be applicable to all users,regardless of their locations.To reduce overhead,a multi-user beam training is proposed to serve all users simultaneously by enhancing each codeword capable of covering multiple areas.Considering a general case that includes users in both fields,simulation results indicate that,without prior knowledge of user distribution,the proposed scheme outperforms state-of-the-art ones in terms of sum rate and overhead.展开更多
基金Gansu Province Basic Research Innovation Group Plan(No.1606RJIA327)Natural Science Foundation of Gansu Provinc(No.1606RJYA225)+1 种基金Lanzhou Jiaotong University Youth Fund(No.2014031)Longyuan Youth Innovative Support Program(No.2016-43)
文摘In this paper,a new idea based on pseudolite signal acquisition method aiming to mitigate the near-far effect problemin the satellite positioning is proposed.After analyzing the signal capture principle based on coherent integration and non-coherentaccumulation,the cross-correlation interference of strong and weak signals is eliminated by means of normalization of reconstructedstrong signal and judgement of the characteristics of the peak value,which can avoid the near-far effect of the pseudolitesignal.It can also estimate all the strong signals without any additional hardware.By building an indoor pseudolite positioningsystem,the capture performance becomes better based on improved acquisition algorithm compared with that based on thenon-coherent accumulation after coherent integration algorithm.The near-far effect is restrained effectively and the probabilityof weak signal detection is increased by25%.
文摘Crosstalk is the main degrading factor in Digital Subscriber Line (DSL) systems which are the result of electromagnetic coupling between two adjacent twisted pairs in a cable. Very-high bit-rate Digital Subscriber Line (VDSL) systems which use higher frequencies for data transmission than the other DSL systems, this effect is more considerable in Bit Error Rate (BER) degradation. This paper considers a complete adaptive iterative water-filling (IWF) algorithm for Resolving Upstream Near-Far Problem in VDSL Systems. The new distributed dynamic spectrum management algorithm is proposed, which improve achievable bit rate of iterative water-filling algorithm. The paper proffers a new power back-off strategy of the spectral mask at the near-end users, in order to protect the far-end users. Simulation of the proposed algorithm indicates that the bit rate is increased considerably rather the IWF and adaptive water-filling (AIWF) algorithms by keeping their low complexity. Furthermore, by adding the number of users in network, the new algorithm achieves performance gains over the AIWF, completely adaptive.
文摘The decorrelating detector for direct-sequence code-division multiple access (DS-CDMA) can afford good data estimate because it does not need to know many parameters of the received signal. However, it shows great performance deprivation when the background noise is high. On the other hand, partial parallel interference canceller (PPIC) has the potential to combat the near-far problem and have much lower computation complexity. But its performance depends on the initial data estimate. An improved PPIC scheme is proposed in this paper to combat the near-far problem. It utilizes the advantages of the two detectors by combining them. The focus of this paper is on the BER performance and the near-far resistance capability of the proposed scheme. Computer simulations demonstrate that the proposed detector has good BER performance and near-far resistance capability.
文摘Recently,holographic multiple-input multiple-output(HMIMO)has motivated its potential use to support high-capacity data transmission with spatially quasi-continuous apertures.As a practical instance of HMIMO,reconfigurable refractive surfaces(RRSs)equipped with numerous metamaterial elements are utilized as antennas by refracting incident signals from signal sources.In this paper,we investigate a multi-user communication system with an RRS deployed as the base station(BS)’s transmit antenna.To mitigate the high overhead of accurate channel state information(CSI)acquisition,the codebook design and beam training are employed to perform beamforming.Given the large scale of RRS,users are likely to be randomly distributed in both the near and far fields around the BS,which is unknown in advance.By considering radiation characteristics in both fields,a near-far field codebook is designed to be applicable to all users,regardless of their locations.To reduce overhead,a multi-user beam training is proposed to serve all users simultaneously by enhancing each codeword capable of covering multiple areas.Considering a general case that includes users in both fields,simulation results indicate that,without prior knowledge of user distribution,the proposed scheme outperforms state-of-the-art ones in terms of sum rate and overhead.
