Xiang Liu

Xiang Liu

Wildau, Brandenburg, Germany
624 followers 500+ connections

Experience

Education

  • University of Southampton Graphic

    University of Southampton

    Published 4 journal papers and 9 international conference papers.
    First to represent the characteristic functions of Rice and Hoyt distributions by confluent hypergeometric functions rather than sums of infinite series.

  • Graduate with Distinction Award

Publications

  • Dynamic Population Estimation Using Anonymized Mobility Data

    SIGSPATIAL 2020: Proceedings of the 28th International Conference on Advances in Geographic Information Systems, Association for Computing Machinery

    Fine population distribution both in space and in time is crucial for epidemic management, disaster prevention, urban planning and more. Human mobility data have a great potential for mapping population distribution at a high level of spatiotemporal resolution. Power law models are the most popular ones for mapping mobility data to population. However, they fail to provide consistent estimations under different spatial and temporal resolutions, i.e. they have to be recalibrated whenever the…

    Fine population distribution both in space and in time is crucial for epidemic management, disaster prevention, urban planning and more. Human mobility data have a great potential for mapping population distribution at a high level of spatiotemporal resolution. Power law models are the most popular ones for mapping mobility data to population. However, they fail to provide consistent estimations under different spatial and temporal resolutions, i.e. they have to be recalibrated whenever the spatial or temporal partitioning scheme changes. We propose a Bayesian model for dynamic population estimation using static census data and anonymized mobility data. Our model gives consistent population estimations under different spatial and temporal resolutions.

    Other authors
    See publication
  • Evaluating Information Content of SNPs for Sample Tagging in Re-sequencing Projects

    Scientific Reports, Nature Publishing Group

    Co-first authored with Max-Planck Institute for Molecular Genetics, Berlin, Germany.

    Sample-tagging is designed for identification of accidental sample mix-up, which is a major issue in re-sequencing studies. In this work, we develop a model to measure the information content of SNPs, so that we can optimize a panel of SNPs that approach the maximal information for discrimination. The analysis shows that as low as 60 optimized SNPs can differentiate the individuals in a population as…

    Co-first authored with Max-Planck Institute for Molecular Genetics, Berlin, Germany.

    Sample-tagging is designed for identification of accidental sample mix-up, which is a major issue in re-sequencing studies. In this work, we develop a model to measure the information content of SNPs, so that we can optimize a panel of SNPs that approach the maximal information for discrimination. The analysis shows that as low as 60 optimized SNPs can differentiate the individuals in a population as large as the present world, and only 30 optimized SNPs are in practice sufficient in labeling up to 100 thousand individuals. In the simulated populations of 100 thousand individuals, the average Hamming distances, generated by the optimized set of 30 SNPs are larger than 18, and the duality frequency, is lower than 1 in 10 thousand. This strategy of sample discrimination is proved robust in large sample size and different datasets. The optimized sets of SNPs are designed for Whole Exome Sequencing, and a program is provided for SNP selection, allowing for customized SNP numbers and interested genes. The sample-tagging plan based on this framework will improve re-sequencing projects in terms of reliability and cost-effectiveness.

    Other authors
    • Hao Hu
    • Wenfei Jin
    • Hans-Hilger Ropers
    • Thomas F. Wienker
    See publication
  • Max-Log-MAP Soft Demapper with Logarithmic Complexity for M-PAM Signals

    IEEE Signal Processing Letters, Institute of Electrical and Electronics Engineers

    A max-log-MAP soft demapping algorithm with logarithmic complexity is proposed for M-PAM signals. Its algorithm complexity is only O(log M) for M-PAM signals, in contrast to O(M log M) as achieved by the conventional max-log-MAP algorithm using exhaustive search. The algorithm applies to both Gray-coded and natural-coded signals.The max-log-MAP algorithm with logarithmic complexity may be straightforwardly extended to rectangular QAM signals when the rectangular QAM signal can be decomposed…

    A max-log-MAP soft demapping algorithm with logarithmic complexity is proposed for M-PAM signals. Its algorithm complexity is only O(log M) for M-PAM signals, in contrast to O(M log M) as achieved by the conventional max-log-MAP algorithm using exhaustive search. The algorithm applies to both Gray-coded and natural-coded signals.The max-log-MAP algorithm with logarithmic complexity may be straightforwardly extended to rectangular QAM signals when the rectangular QAM signal can be decomposed into two independent PAM signals.

    See publication
  • Framework Based on Shannon-Entropy of SNP-Marker Combinations for Sample Tagging in Re-sequencing Projects

    25th Annual Meeting of the German Society of Humangenetics

    Co-first authored with Max-Planck Institute for Molecular Genetics, Berlin, Germany.

    Other authors
    • Hao Hu
    • Wenfei Jin
    • Hans-Hilger Ropers
    • Thomas F. Wienker
    See publication

Patents

  • Estimation of Mobile Device Count

    Issued US 10904853

    A method, system, and apparatus for estimation of a count of mobile devices include receiving one or more probe data points including a location and a session identifier, constructing a trajectory including the one or more probe data points having a same session identifier, constructing a trajectory including the one or more probe data points having a same session identifier and generated by one mobile device of the plurality of the mobile devices, dividing the trajectory area by an area of the…

    A method, system, and apparatus for estimation of a count of mobile devices include receiving one or more probe data points including a location and a session identifier, constructing a trajectory including the one or more probe data points having a same session identifier, constructing a trajectory including the one or more probe data points having a same session identifier and generated by one mobile device of the plurality of the mobile devices, dividing the trajectory area by an area of the observation area, and estimating the count of mobile devices in the observation area from at least the normalized trajectory area. A path of the trajectory is based on the location of the one or more probe data points expanding the path of the trajectory by a radius where a result of the expanding is a trajectory area. A result of the dividing is a first normalized trajectory area.

    Other inventors
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  • Estimation of Mobile Device Count

    Issued US 10772068

    A method, system, and apparatus for estimation of a number of mobile devices include receiving one or more probe data points including a location, a session identifier, and a timestamp, constructing a trajectory including the one or more probe data points having a same session identifier, calculating a trajectory duration for the trajectory based on the timestamps of the one or more probe data points, calculating a normalized trajectory from the trajectory duration and a predetermined…

    A method, system, and apparatus for estimation of a number of mobile devices include receiving one or more probe data points including a location, a session identifier, and a timestamp, constructing a trajectory including the one or more probe data points having a same session identifier, calculating a trajectory duration for the trajectory based on the timestamps of the one or more probe data points, calculating a normalized trajectory from the trajectory duration and a predetermined observation duration, and estimating the number of mobile devices from at least the normalized trajectory. A path of the trajectory is based on the location of the one or more probe data points.

    Other inventors
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  • Method, Apparatus, and System for Estimating Continuous Population Density Change in Urban Areas

    Filed US 17/085899

  • Estimation of Mobile Device Count

    Filed EU 20175343

    A method, system, and apparatus for estimation of a number of mobile devices include receiving one or more probe data points including a location, a session identifier, and a timestamp, constructing a trajectory including the one or more probe data points having a same session identifier, calculating a trajectory duration for the trajectory based on the timestamps of the one or more probe data points, calculating a normalized trajectory from the trajectory duration and a predetermined…

    A method, system, and apparatus for estimation of a number of mobile devices include receiving one or more probe data points including a location, a session identifier, and a timestamp, constructing a trajectory including the one or more probe data points having a same session identifier, calculating a trajectory duration for the trajectory based on the timestamps of the one or more probe data points, calculating a normalized trajectory from the trajectory duration and a predetermined observation duration, and estimating the number of mobile devices from at least the normalized trajectory. A path of the trajectory is based on the location of the one or more probe data points.

    Other inventors
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  • Data Fusion for Dynamic Population Estimation

    Filed US 16/708777

  • Method and Apparatus for Estimation of Waiting Time to Park

    Issued US 10169996

    An approach is provided for estimation of waiting time to park. The approach involves processing parking data from a parking area to determine a probability that all parking spots in the parking area are occupied. The parking data is collected from one or more parking sensors. The approach also involves building a remaining parking duration model for a plurality of cars parked in said all parking spots based on the parking data. The approach further involves calculating an estimated conditional…

    An approach is provided for estimation of waiting time to park. The approach involves processing parking data from a parking area to determine a probability that all parking spots in the parking area are occupied. The parking data is collected from one or more parking sensors. The approach also involves building a remaining parking duration model for a plurality of cars parked in said all parking spots based on the parking data. The approach further involves calculating an estimated conditional waiting time to park in the parking area based on the remaining parking duration model. The approach further involves calculating an estimated unconditional waiting time to park in the parking area based on the blocking probability and the conditional waiting time to park.

    See patent
  • Method and Apparatus for Measurement of Parking Duration from Anonymized Data

    Issued US 10032368

    An approach is provided for measuring parking duration from anonymized data. The approach involves receiving parking data indicating anonymized park in and park out events from connected vehicles. The approach also involves performing a first filtering of the parking data to remove the park out events that occur within a time interval and before a first park in event occurring within the time interval, and to remove the park in events that occur within the time interval and after a last park…

    An approach is provided for measuring parking duration from anonymized data. The approach involves receiving parking data indicating anonymized park in and park out events from connected vehicles. The approach also involves performing a first filtering of the parking data to remove the park out events that occur within a time interval and before a first park in event occurring within the time interval, and to remove the park in events that occur within the time interval and after a last park out event occurring within the time interval. The approach further involves performing a second filtering of the parking data remaining after the first filtering to remove park in events or park out events so that the numbers of park in and park out events are balanced. The approach then involves calculating parking duration data from the park in and park out events remaining after the second filtering.

    Other inventors
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  • Space- and Latency-Efficient HSDPA Receiver Using A Symbol Deinterleaver

    Issued EU 2827546

    A method at a mobile device, the method comprising: receiving one or more data symbols; determining reduced symbols for each of the data symbols, the reduced symbols corresponding to each of at least two orthogonal components of the data symbols; and, storing the reduced symbols in a symbol buffer.

    Other inventors
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  • Space and Latency-Efficient HSDPA Receiver Using A Symbol De-interleaver

    Issued US 09509545

    A method at a mobile device, the method comprising: receiving one or more data symbols; determining reduced symbols for each of the data symbols, the reduced symbols corresponding to each of at least two orthogonal components of the data symbols; and, storing the reduced symbols in a symbol buffer.

    Other inventors
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  • Computation of reliability values

    Filed EU 13159254

    There are disclosed systems and methods for computing a reliability value for a bit of a received symbol value y associated with a constellation. In one embodiment, the method comprises computing the reliability value by obtaining a first minimum distance value, the first minimum distance value being a function of an absolute magnitude of an initial value associated with the bit, and combining the first minimum distance value with a second minimum distance value, the second minimum distance…

    There are disclosed systems and methods for computing a reliability value for a bit of a received symbol value y associated with a constellation. In one embodiment, the method comprises computing the reliability value by obtaining a first minimum distance value, the first minimum distance value being a function of an absolute magnitude of an initial value associated with the bit, and combining the first minimum distance value with a second minimum distance value, the second minimum distance value being a function of a distance between the received symbol value y and a symbol xb̂ in the constellation corresponding to a most likely pattern of bits transmitted given the received symbol value y.

    Other inventors
    • Martin Kosakowski
    See patent
  • Method, Apparatus, and Computer Program Product for Map Data Conflation

    Filed US 17/934900

    Other inventors
  • Method, Apparatus, and Computer Program Product for Dynamic Population Estimation

    Filed US 63/071626

  • Computation of Reliability Values

    Filed US 13826854

    There are disclosed systems and methods for computing a reliability value for a bit of a received symbol value y associated with a constellation. In one embodiment, the method comprises computing the reliability value by obtaining a first minimum distance value, the first minimum distance value being a function of an absolute magnitude of an initial value associated with the bit, and combining the first minimum distance value with a second minimum distance value, the second minimum distance…

    There are disclosed systems and methods for computing a reliability value for a bit of a received symbol value y associated with a constellation. In one embodiment, the method comprises computing the reliability value by obtaining a first minimum distance value, the first minimum distance value being a function of an absolute magnitude of an initial value associated with the bit, and combining the first minimum distance value with a second minimum distance value, the second minimum distance value being a function of a distance between the received symbol value y and a symbol x_b in the constellation corresponding to a most likely pattern of bits transmitted given the received symbol value y.

    Other inventors
    • Martin Kosakowski
    See patent

Projects

  • Sample Tagging for Improving Re-Sequencing

    -

    Partner: Max-Planck Institute for Molecular Genetics, Germany
    The project proposed a robust and cost-efficient scheme in order to differentiate the samples of any two individuals due to accidental sample mix-ups in human genome re-sequencing projects. My contributions were
    * Designing a statistical model for the project based on information theoy.
    * Mathematically proving the minimum number of SNPs (Single Nucleotide Polymorphism) required for differentiating all individuals in a…

    Partner: Max-Planck Institute for Molecular Genetics, Germany
    The project proposed a robust and cost-efficient scheme in order to differentiate the samples of any two individuals due to accidental sample mix-ups in human genome re-sequencing projects. My contributions were
    * Designing a statistical model for the project based on information theoy.
    * Mathematically proving the minimum number of SNPs (Single Nucleotide Polymorphism) required for differentiating all individuals in a population at a given confidence level.
    * Designing an efficient algorithm to search the minimum set of SNPs out of more than 1 million SNPs.

Languages

  • English

    Professional working proficiency

  • German

    Limited working proficiency

  • Chinese

    Native or bilingual proficiency

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