Tingting Liu - Academia.edu (original) (raw)

Papers by Tingting Liu

Research paper thumbnail of Joint Transmitter-Receiver Frequency-Domain Equalization in Multicarrier Code-Division Multiplexing Systems

Joint transmitter-receiver optimization in generalized multicarrier code-division multiplexing (G... more Joint transmitter-receiver optimization in generalized multicarrier code-division multiplexing (GMC-CDM) systems is investigated in this paper. The optimization consists of a one-tap post-frequency-domain equalizer (post-FDE) and a onetap pre-FDE. While the one-tap post-FDE is optimized under the criterion of minimum mean square error (MMSE), the one-tap pre-FDE is achieved through three stages of optimization, which are operated at different levels and motivated to achieve, possibly, different objectives, including maximum throughput and maximum reliability. Specifically, in our three-stage pre-FDE, the first-stage pre-FDE is operated at the symbol level, concerning only the symbols within a group. The second-stage pre-FDE is carried out at the group level for harmonization among the groups. Finally, the third-stage pre-FDE handles group partition. In this paper, the error and throughput performance of the GMC-CDM systems is investigated when assuming communications over frequency-selective Rayleigh fading channels. It can be shown that the reliability or throughput of the GMC-CDM systems can be significantly improved by employment of the proposed pre-and post-FDE schemes. Furthermore, the pre-and post-FDE algorithms obtained can be implemented with high flexibility, which facilitates a GMC-CDM system to achieve a good tradeoff between its throughput and reliability.

Research paper thumbnail of A Symbol-Level FDE and Spread-Spectrum Mode Design for Multi-Code Multiple Access Systems

Design of equalizers and spread-spectrum modes or code allocation schemes is crucial for achievin... more Design of equalizers and spread-spectrum modes or code allocation schemes is crucial for achieving good performance multi-code multiple access systems. In this paper, a symbol- level frequency domain equalizer and spread-spectrum mode are jointly designed to maximize the diversity gain with low complexity. Since the proposed transceiver scheme is independent of the orthogonal codes, it can be applied to direct sequence code division multiple access (DS-CDMA), multi-carrier CDMA (MC-CDMA) and orthogonal frequency division multiple access (OFDMA) systems. Simulation results are provided which validate the theoretical analysis.

Research paper thumbnail of A low-complexity subcarrier-power allocation scheme for frequency-division multiple-access systems

IEEE Transactions on Wireless Communications, 2010

This letter aims to design a low-complexity subcarrier-power allocation scheme to improve the com... more This letter aims to design a low-complexity subcarrier-power allocation scheme to improve the communication reliability of various types of frequency-division multipleaccess (FDMA) systems. Both uplink and downlink are considered. Specifically, a low-complexity worst subcarrier avoiding (WSA) subcarrier-allocation scheme is proposed, in order to avoid assigning users the subcarriers experiencing severe fading. After the subcarrier-allocation, channel-inversion assisted powerallocation is employed to assign the subcarriers the corresponding power. Our studies and simulation results show that the achievable error performance of the FDMA systems employing the proposed subcarrier-power allocation algorithm is independent of the multiplexing method. The proposed algorithm outperforms the existing subcarrier-power allocation algorithms that have a similar complexity as the proposed one.

Research paper thumbnail of IrrE, a Global Regulator of Extreme Radiation Resistance in Deinococcus radiodurans, Enhances Salt Tolerance in Escherichia coli and Brassica napus

PLOS One, 2009

Background: Globally, about 20% of cultivated land is now affected by salinity. Salt tolerance is... more Background: Globally, about 20% of cultivated land is now affected by salinity. Salt tolerance is a trait of importance to all crops in saline soils. Previous efforts to improve salt tolerance in crop plants have met with only limited success. Bacteria of the genus Deinococcus are known for their ability to survive highly stressful conditions, and therefore possess a unique pool of genes conferring extreme resistance. In Deinococcus radiodurans, the irrE gene encodes a global regulator responsible for extreme radioresistance.

Research paper thumbnail of Laser-induced dissociation and explosion of methane and methanol

Journal of Physics B-atomic Molecular and Optical Physics, 2002

... and methanol Chengyin Wu, Haizhen Ren, Tingting Liu, Ri Ma, Hong Yang, Hongbing Jiang and Qih... more ... and methanol Chengyin Wu, Haizhen Ren, Tingting Liu, Ri Ma, Hong Yang, Hongbing Jiang and Qihuang Gong1 State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, People's Republic of China E-mail: qhgong@pku.edu.cn ...

Research paper thumbnail of Joint Transmitter-Receiver Frequency-Domain Equalization in Multicarrier Code-Division Multiplexing Systems

Joint transmitter-receiver optimization in generalized multicarrier code-division multiplexing (G... more Joint transmitter-receiver optimization in generalized multicarrier code-division multiplexing (GMC-CDM) systems is investigated in this paper. The optimization consists of a one-tap post-frequency-domain equalizer (post-FDE) and a onetap pre-FDE. While the one-tap post-FDE is optimized under the criterion of minimum mean square error (MMSE), the one-tap pre-FDE is achieved through three stages of optimization, which are operated at different levels and motivated to achieve, possibly, different objectives, including maximum throughput and maximum reliability. Specifically, in our three-stage pre-FDE, the first-stage pre-FDE is operated at the symbol level, concerning only the symbols within a group. The second-stage pre-FDE is carried out at the group level for harmonization among the groups. Finally, the third-stage pre-FDE handles group partition. In this paper, the error and throughput performance of the GMC-CDM systems is investigated when assuming communications over frequency-selective Rayleigh fading channels. It can be shown that the reliability or throughput of the GMC-CDM systems can be significantly improved by employment of the proposed pre-and post-FDE schemes. Furthermore, the pre-and post-FDE algorithms obtained can be implemented with high flexibility, which facilitates a GMC-CDM system to achieve a good tradeoff between its throughput and reliability.

Research paper thumbnail of A Symbol-Level FDE and Spread-Spectrum Mode Design for Multi-Code Multiple Access Systems

Design of equalizers and spread-spectrum modes or code allocation schemes is crucial for achievin... more Design of equalizers and spread-spectrum modes or code allocation schemes is crucial for achieving good performance multi-code multiple access systems. In this paper, a symbol- level frequency domain equalizer and spread-spectrum mode are jointly designed to maximize the diversity gain with low complexity. Since the proposed transceiver scheme is independent of the orthogonal codes, it can be applied to direct sequence code division multiple access (DS-CDMA), multi-carrier CDMA (MC-CDMA) and orthogonal frequency division multiple access (OFDMA) systems. Simulation results are provided which validate the theoretical analysis.

Research paper thumbnail of A low-complexity subcarrier-power allocation scheme for frequency-division multiple-access systems

IEEE Transactions on Wireless Communications, 2010

This letter aims to design a low-complexity subcarrier-power allocation scheme to improve the com... more This letter aims to design a low-complexity subcarrier-power allocation scheme to improve the communication reliability of various types of frequency-division multipleaccess (FDMA) systems. Both uplink and downlink are considered. Specifically, a low-complexity worst subcarrier avoiding (WSA) subcarrier-allocation scheme is proposed, in order to avoid assigning users the subcarriers experiencing severe fading. After the subcarrier-allocation, channel-inversion assisted powerallocation is employed to assign the subcarriers the corresponding power. Our studies and simulation results show that the achievable error performance of the FDMA systems employing the proposed subcarrier-power allocation algorithm is independent of the multiplexing method. The proposed algorithm outperforms the existing subcarrier-power allocation algorithms that have a similar complexity as the proposed one.

Research paper thumbnail of IrrE, a Global Regulator of Extreme Radiation Resistance in Deinococcus radiodurans, Enhances Salt Tolerance in Escherichia coli and Brassica napus

PLOS One, 2009

Background: Globally, about 20% of cultivated land is now affected by salinity. Salt tolerance is... more Background: Globally, about 20% of cultivated land is now affected by salinity. Salt tolerance is a trait of importance to all crops in saline soils. Previous efforts to improve salt tolerance in crop plants have met with only limited success. Bacteria of the genus Deinococcus are known for their ability to survive highly stressful conditions, and therefore possess a unique pool of genes conferring extreme resistance. In Deinococcus radiodurans, the irrE gene encodes a global regulator responsible for extreme radioresistance.

Research paper thumbnail of Laser-induced dissociation and explosion of methane and methanol

Journal of Physics B-atomic Molecular and Optical Physics, 2002

... and methanol Chengyin Wu, Haizhen Ren, Tingting Liu, Ri Ma, Hong Yang, Hongbing Jiang and Qih... more ... and methanol Chengyin Wu, Haizhen Ren, Tingting Liu, Ri Ma, Hong Yang, Hongbing Jiang and Qihuang Gong1 State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, People's Republic of China E-mail: qhgong@pku.edu.cn ...