Cellular vehicle-to-everything(C-V2X) communications is regarded as a promising and feasible solution for 5G-enabled vehicular communications and networking. In this paper, we investigate the pilot design and channel ...Cellular vehicle-to-everything(C-V2X) communications is regarded as a promising and feasible solution for 5G-enabled vehicular communications and networking. In this paper, we investigate the pilot design and channel estimation problem in MIMO-OFDM-based C-V2X systems with severe co-channel interference due to spectrum reusing among different V2X communication links. By using zero-correlation zone(ZCZ) sequences, we provide an interference-free pilot design scheme and a corresponding time-domain(TD) correlation-based channel estimation(TD-CCE) method. We employ the ZCZ sequences from the same family set to be designed as the TD pilot symbols and guarantee the pilot sequeneces for neighboring V2X communication links are code-division multiplexing(CDM). The co-channel pilot interference of the deisgned pilot symbols can be effectively eliminated by exploiting the provided TD-CCE method. Simulation results indicate that the accuracy of channel estimation can be effectively improved by the proposed scheme, whose performance is close to that of the non-interference situation.展开更多
In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlatio...In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.展开更多
This paper deals with optimal training design and placement over multiple orthogonal frequency division multiplexing(OFDM) symbols for the least squares(LS) channel estimation in multiple-input multipleoutput(MIMO) OF...This paper deals with optimal training design and placement over multiple orthogonal frequency division multiplexing(OFDM) symbols for the least squares(LS) channel estimation in multiple-input multipleoutput(MIMO) OFDM systems.First,the optimal pilot sequences over multiple OFDM symbols are derived by co-cyclic Jacket matrices based on the minimum mean square error(MSE) of the LS channel estimation.Then,an enhanced channel estimation method using sliding window is proposed to improve further the performance for the optimal pilot sequences in fast-varying channels.Simulation results show that the enhancedmethod can efficiently improve the performances for the optimal pilot sequences over two and four OFDM symbols,especially in fast-varying channels.展开更多
文摘Cellular vehicle-to-everything(C-V2X) communications is regarded as a promising and feasible solution for 5G-enabled vehicular communications and networking. In this paper, we investigate the pilot design and channel estimation problem in MIMO-OFDM-based C-V2X systems with severe co-channel interference due to spectrum reusing among different V2X communication links. By using zero-correlation zone(ZCZ) sequences, we provide an interference-free pilot design scheme and a corresponding time-domain(TD) correlation-based channel estimation(TD-CCE) method. We employ the ZCZ sequences from the same family set to be designed as the TD pilot symbols and guarantee the pilot sequeneces for neighboring V2X communication links are code-division multiplexing(CDM). The co-channel pilot interference of the deisgned pilot symbols can be effectively eliminated by exploiting the provided TD-CCE method. Simulation results indicate that the accuracy of channel estimation can be effectively improved by the proposed scheme, whose performance is close to that of the non-interference situation.
基金supported by the Scientific Research Foundation for the Doctor′s Degree,Beijing University of Technology(No.X0002012200903)the State Key Laboratory of Integrated Services Networks(Xidian University),China(No.ISN10-02)
文摘In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.
基金the National Natural Science Foundation of China (Nos. 60332030 and 60625103)the Science and Technology Commission of Shanghai Municipality (STCSM) (No. 05DZ22102)the National High Technology Research and Development Program(863) of China (No. 2007AA01Z237)
文摘This paper deals with optimal training design and placement over multiple orthogonal frequency division multiplexing(OFDM) symbols for the least squares(LS) channel estimation in multiple-input multipleoutput(MIMO) OFDM systems.First,the optimal pilot sequences over multiple OFDM symbols are derived by co-cyclic Jacket matrices based on the minimum mean square error(MSE) of the LS channel estimation.Then,an enhanced channel estimation method using sliding window is proposed to improve further the performance for the optimal pilot sequences in fast-varying channels.Simulation results show that the enhancedmethod can efficiently improve the performances for the optimal pilot sequences over two and four OFDM symbols,especially in fast-varying channels.
