Sam Liang

Sam Liang

Palo Alto, California, United States
15K followers 500+ connections

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  • Otter.ai Graphic

    Otter.ai

    Palo Alto, CA

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    Palo Alto, California, United States

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    Palo Alto, CA

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    Menlo Park, California

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    Mountain View, CA

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Education

  • Stanford University Graphic

    Stanford

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    Activities and Societies: Tennis

    Specialized in large scale Internet distributed systems, in particular TCP/IP, IP multicast, multimedia over IP. Ph.D advisor: Professor David Cheriton, who wrote the very first check of $100K to Larry Page and Sergey Brin to start Google in 1997.

  • Activities and Societies: Teaching Assistant

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    Activities and Societies: Soccer, Badminton

Volunteer Experience

Publications

  • TCP-RTM: Using TCP for real time multimedia applications

    International Conference on Network Protocols

    By conventional wisdom dating back to the genesis of the Internet, TCP is not suitable for realtime applications because it favors reliability over timeliness. The result has been a proliferation of application-specific and candidate real-time transport protocols, none of which has achieved the maturity and acceptance of TCP. To our knowledge, there has not been much prior study to ask the basic engineering question: What changes in TCP and its use would be required to allow it to be used for…

    By conventional wisdom dating back to the genesis of the Internet, TCP is not suitable for realtime applications because it favors reliability over timeliness. The result has been a proliferation of application-specific and candidate real-time transport protocols, none of which has achieved the maturity and acceptance of TCP. To our knowledge, there has not been much prior study to ask the basic engineering question: What changes in TCP and its use would be required to allow it to be used for real-time network applications of interest? In this paper, we investigate exactly this question. Our testbed-based and public Internet experiment results show that the combination of a relatively modest extension to TCP, what we call real-time mode (RTM), and several application techniques allow real-time applications to operate well over TCP, making all the benefits of TCP, including error recovery, available to the real-time application developers. The TCP-RTM approach also leads to real-time applications that are responsive to network congestion, sharing the network resources fairly with other TCP applications.

    Other authors
    • David Cheriton
    See publication
  • TCP-SMO: Extending TCP to Support Medium-Scale Multicast Applications

    IEEE Infocom

    Abstract—Scalable reliable multicast protocols have been a focus of recent research, tackling the problem of efficient reliable data delivery to an arbitrarily large number of receivers. Yet, the common applications of multicast, such as multi-point file delivery, or video streaming from a media server, typically only involve a moderate number of receivers, such as a thousand or fewer. Moreover, because of the limited deployment of these specialized multicast protocols, it is common for…

    Abstract—Scalable reliable multicast protocols have been a focus of recent research, tackling the problem of efficient reliable data delivery to an arbitrarily large number of receivers. Yet, the common applications of multicast, such as multi-point file delivery, or video streaming from a media server, typically only involve a moderate number of receivers, such as a thousand or fewer. Moreover, because of the limited deployment of these specialized multicast protocols, it is common for applications to instead use multiple TCP connections, one for each receiver, to implement multi-point delivery when feasible, causing a significant demand on the transmission server and the downstream links. In this paper, we describe a multicast extension to TCP, called the Single-source Multicast Optimization (SMO), that optimizes this case of multipoint delivery, providing the benefits of multicast together with the familiar features and API of TCP. Our results from experiments based on a Linux implementation and performed on a test-bed show that TCP-SMO requires just a modest extension to the TCP implementation and provides the scalable performance of multicast up to over a thousand receivers, thereby satisfying the common case requirements. In addition, used with TCP-RTM (Real-Time Mode), TCP-SMO also supports real-time multimedia multicast applications well.

    Other authors
    • David Cheriton
    See publication

Patents

  • Systems and methods for capturing, processing, and rendering one or more context-aware moment-associating elements

    Issued US 11,024,316

    Computer-implemented method and system for receiving and processing one or more moment-associating elements. For example, the computer-implemented method includes receiving the one or more moment-associating elements, transforming the one or more moment-associating elements into one or more pieces of moment-associating information, and transmitting at least one piece of the one or more pieces of moment-associating information. The transforming the one or more moment-associating elements into…

    Computer-implemented method and system for receiving and processing one or more moment-associating elements. For example, the computer-implemented method includes receiving the one or more moment-associating elements, transforming the one or more moment-associating elements into one or more pieces of moment-associating information, and transmitting at least one piece of the one or more pieces of moment-associating information. The transforming the one or more moment-associating elements into one or more pieces of moment-associating information includes segmenting the one or more moment-associating elements into a plurality of moment-associating segments, assigning a segment speaker for each segment of the plurality of moment-associating segments, transcribing the plurality of moment-associating segments into a plurality of transcribed segments, and generating the one or more pieces of moment-associating information based on at least the plurality of transcribed segments and the segment speaker assigned for each segment of the plurality of moment-associating segments.

    See patent
  • Systems and methods for processing and presenting conversations

    Issued US 10,978,073

    System and method for processing and presenting a conversation. For example, a system includes a sensor configured to capture an audio-form conversation, and a processor configured to automatically transform the audio-form conversation into a transformed conversation. The transformed conversation includes a synchronized text, and the synchronized text is synchronized with the audio-form conversation. Additionally, the system includes a presenter configured to present the transformed…

    System and method for processing and presenting a conversation. For example, a system includes a sensor configured to capture an audio-form conversation, and a processor configured to automatically transform the audio-form conversation into a transformed conversation. The transformed conversation includes a synchronized text, and the synchronized text is synchronized with the audio-form conversation. Additionally, the system includes a presenter configured to present the transformed conversation including the synchronized text and the audio-form conversation.

    See patent
  • Control of activation of location-related sensors of a mobile device

    Issued US 9,167,529

    Methods, systems and apparatuses for selecting which of a plurality of sensors to use for location detection of a mobile device are disclosed. One method includes activating lowest-power location-related sensors of the mobile device at power up of a mobile device, and activating medium-power location-related sensors of the mobile device upon detection of motion of the mobile device and/or a change in a wireless connection to the mobile device.

    See patent
  • Persistently determining and sharing user stays of a user of a mobile device

    Issued US 9,037,485

    Methods, systems and apparatuses for automatically detecting and sharing user stays of a mobile device of a user are disclosed. One method includes persistently collecting location information, determining a group of users for sharing the user stays, determining whether the mobile device is within a specific distance of a specific location for at least specific minimum duration based on the location information, determining a user stay based on the location information and the specific…

    Methods, systems and apparatuses for automatically detecting and sharing user stays of a mobile device of a user are disclosed. One method includes persistently collecting location information, determining a group of users for sharing the user stays, determining whether the mobile device is within a specific distance of a specific location for at least specific minimum duration based on the location information, determining a user stay based on the location information and the specific distance, determining if the user stay is private or public to at least a portion of the group of users based on preferences of the user and the location information, and sharing the user stay with the at least the portion of the group of users by sending notifications to the group of users if the user stay is determined to be public to the at least the portion of the group of users.

    See patent
  • Determining user stays of a user of a mobile device

    Issued US 8,990,107

    Methods, systems and apparatuses for automatically determining user stays of a user of a mobile device are disclosed. One embodiment includes a network server operative to receive sensed location information of a mobile device. Further, the network server and/or a controller of the mobile device are operative to determine the mobile device is within a specific distance of a specific location for at least specific minimum time duration based on the location information, determine a start time of…

    Methods, systems and apparatuses for automatically determining user stays of a user of a mobile device are disclosed. One embodiment includes a network server operative to receive sensed location information of a mobile device. Further, the network server and/or a controller of the mobile device are operative to determine the mobile device is within a specific distance of a specific location for at least specific minimum time duration based on the location information, determine a start time of a user stay based on the location information, the specific location and the specific distance, and determine an end time of the user stay based on the location information, the specific location and the specific distance.

    See patent
  • Determining points of interest of a mobile user

    Issued US 8,958,822

    Methods, systems and apparatus for tracking points of interest of a user of a mobile device are disclosed. One method includes determining points of interest of a user of a mobile device. The method includes obtaining user-related information, wherein the user-related information includes spatial information about the user, and determining at least one point of interest of the user based on the user-related information. Another embodiment includes an apparatus for determining points of interest…

    Methods, systems and apparatus for tracking points of interest of a user of a mobile device are disclosed. One method includes determining points of interest of a user of a mobile device. The method includes obtaining user-related information, wherein the user-related information includes spatial information about the user, and determining at least one point of interest of the user based on the user-related information. Another embodiment includes an apparatus for determining points of interest of a user. For one embodiment, the apparatus is a mobile device. The mobile device is operative to obtain user-related information, wherein the user-related information comprising spatial information about the user, and the mobile device is operative to determine at least one point of interest of the user based on the user-related information.

    See patent
  • Controlling operational states of a location sensing system of a mobile device

    Issued US 8,948,781

    Methods, systems and apparatuses for controlling a location sensing system of a mobile device are disclosed. One method includes collecting location related information of the mobile device. The method further includes controllably setting the mobile device to operate in one of a high-power state, a low-power state, or a transitional state based on the collected location related information, wherein a satellite-based positioning system receiver of the mobile device generates location…

    Methods, systems and apparatuses for controlling a location sensing system of a mobile device are disclosed. One method includes collecting location related information of the mobile device. The method further includes controllably setting the mobile device to operate in one of a high-power state, a low-power state, or a transitional state based on the collected location related information, wherein a satellite-based positioning system receiver of the mobile device generates location information in the transitional state and in the on-state, and the satellite-based positioning system receiver does not generate location information in the low-power state. When operating in the transitional state, the mobile device repeatedly checks the collected location related information and transitions to the low-power state or the high-power state based on the collected location related information.

    See patent
  • Mobile Device User Behavior Analysis and Authentication

    Issued US 8892461

    Methods, systems and apparatuses for authenticating a user of a mobile device are disclosed. One method includes tracking a plurality of locations of the mobile device, tracking motion behavior of the mobile device, and generating a user profile for the user over a period of time based on the tracked plurality of locations and the tracked motion behavior. A present user of the mobile device is authenticated based on a comparison of the user profile with a present user profile of the present…

    Methods, systems and apparatuses for authenticating a user of a mobile device are disclosed. One method includes tracking a plurality of locations of the mobile device, tracking motion behavior of the mobile device, and generating a user profile for the user over a period of time based on the tracked plurality of locations and the tracked motion behavior. A present user of the mobile device is authenticated based on a comparison of the user profile with a present user profile of the present user, wherein the present user profile comprises recent location information of the mobile device and recent motion behavior of the mobile device.

    See patent
  • Location Based User Behavior Analysis and Applications

    Issued US 8725569

    Methods, systems and apparatuses for generating a user profile of a mobile device user are disclosed. One method includes tracking user stays of the user over time, wherein the user stays include at least one location, and generating the user profile based at least in part on at least one of an arrival time, a time duration or a frequency of visits of the user at each of the user stays. Another method includes determining a current state of a mobile device user. The method includes tracking…

    Methods, systems and apparatuses for generating a user profile of a mobile device user are disclosed. One method includes tracking user stays of the user over time, wherein the user stays include at least one location, and generating the user profile based at least in part on at least one of an arrival time, a time duration or a frequency of visits of the user at each of the user stays. Another method includes determining a current state of a mobile device user. The method includes tracking locations of user stays of the mobile device user over time, and determining a current state of a mobile device user based on user stays within a predetermined time of a present time, wherein the predetermined time is dependent upon an application of the user device or an observed behavior of a user of the user device.

    See patent
  • System and Method of Using Spatial and Temporal Signals to Identify and Prevent Attacks

    Issued US 8489732

    Systems and methods according to aspects of the invention verify requests for information over a network. Computing devices communicating over a network transmit numerous signals with various types of information including spatial information, temporal information, device-specific information, and transmission specific information. This information may be used to generate statistical records of valid request for information. Various combinations of these signals may be used to determine whether…

    Systems and methods according to aspects of the invention verify requests for information over a network. Computing devices communicating over a network transmit numerous signals with various types of information including spatial information, temporal information, device-specific information, and transmission specific information. This information may be used to generate statistical records of valid request for information. Various combinations of these signals may be used to determine whether a request for information is a valid request based on the statistical records associated with the signals. Where a request for information has been verified, the system and method may provide the information. Where the request for information has not been verified, the system and method may deny the request for information. Thus the system and method may be used to prevent and block scraping and spamming attacks.

    See patent
  • Location Data Quarantine System

    Issued US 8423791

    A computer-implemented method and system of quarantining user location information receives from a user device user location information that includes personally identifiable user data and user position data associated with one or more geographic positions of the user. The user location information is temporarily stored in a quarantine data storage database for a predetermined quarantine time, during such time it can be used for various analyses. After the quarantine time, personally…

    A computer-implemented method and system of quarantining user location information receives from a user device user location information that includes personally identifiable user data and user position data associated with one or more geographic positions of the user. The user location information is temporarily stored in a quarantine data storage database for a predetermined quarantine time, during such time it can be used for various analyses. After the quarantine time, personally identifiable user data of the user location information is filtered out before the user position data is sent for long-term storage to a filtered data storage system.

    See patent
  • User Location Reputation System

    Issued US 8370340

    A computer-implemented method and system of building a user reputation database for use in a user location data system. The method and system receive user location information containing personally identifiable data of a user and user position data. The user position data may or may not represent one or more actual geographic positions of the user. The user location information is temporarily stored and analyzed to provide a spam score associated with the user position data indicative of…

    A computer-implemented method and system of building a user reputation database for use in a user location data system. The method and system receive user location information containing personally identifiable data of a user and user position data. The user position data may or may not represent one or more actual geographic positions of the user. The user location information is temporarily stored and analyzed to provide a spam score associated with the user position data indicative of whether the user position data represents the actual geographic positions of the user. Data indicative of the spam score is also provided to user reputation database to store a user reputation score associated with the user.

    See patent
  • Determining Throughput Between Hosts

    Issued US 7564781

    An apparatus and method of determining throughput between a first host and a second host of at least one network is disclosed. The method includes the first host intentionally corrupting ICMP packets by manipulating a checksum of the ICMP packets. The first host sends the corrupted ICMP packets to the second host through the at least one network. The first host additionally sends non-corrupted ICMP packets to the second host. Based on responses from second host to the ICMP packets, the first…

    An apparatus and method of determining throughput between a first host and a second host of at least one network is disclosed. The method includes the first host intentionally corrupting ICMP packets by manipulating a checksum of the ICMP packets. The first host sends the corrupted ICMP packets to the second host through the at least one network. The first host additionally sends non-corrupted ICMP packets to the second host. Based on responses from second host to the ICMP packets, the first host estimates a throughput between the first host and the second host. The throughput includes a first direction throughput from the first host to the second host, a second direction throughput from the second host to the first host, and a round trip throughput between the first host and the second host.

    See patent
  • Real-Time Determination of User Stays of a Mobile Device

    Filed US 20130252638

    Methods, systems and apparatuses for real-time determination of user stays of a mobile device are disclosed. One computer-implemented method includes receiving, by a server, an incoming stream of location point information of the mobile device. Further, the method includes continuously calculating, by the server, a current centroid of a current user stay based on a location point of a start time of the current user stay, each location point occurring between the start time and a current…

    Methods, systems and apparatuses for real-time determination of user stays of a mobile device are disclosed. One computer-implemented method includes receiving, by a server, an incoming stream of location point information of the mobile device. Further, the method includes continuously calculating, by the server, a current centroid of a current user stay based on a location point of a start time of the current user stay, each location point occurring between the start time and a current incoming location point, until an outlier location point is detected, wherein the outlier is detected if located more than a threshold distance away from the current centroid.

    Other inventors
    See patent
  • Wireless Network-Based Location Approximation

    Filed US 20100020776

    The invention pertains to location approximation of devices, e.g., wireless access points and client devices in a wireless network. Location estimates may be obtained by observation/analysis of packets transmitted or received by the access point. For instance, data rate information associated with a packet is used to approximate the distance between a client device and the access point. This may be coupled with known positioning information to arrive at an approximate location for the access…

    The invention pertains to location approximation of devices, e.g., wireless access points and client devices in a wireless network. Location estimates may be obtained by observation/analysis of packets transmitted or received by the access point. For instance, data rate information associated with a packet is used to approximate the distance between a client device and the access point. This may be coupled with known positioning information to arrive at an approximate location for the access point. Confidence information and metrics about whether a device is an access point and the location of that device may also be determined. Accuracy of the location determination may be affected by factors including propagation and environmental factors, transmit power, antenna gain and diversity, etc. A location information database of access points may employ measurements from various devices over time. Such information may identify the location of client devices and provide location-based services to them.

    See patent
  • Determining Advertising Conversion

    Filed US 20100153216

    The present disclosure relates to a system and method for determining advertising conversion metrics. In some implementations, a method includes receiving spatial information associated with a user in connection with an advertisement presented through a wireless device. The advertisement is associated with an offline store having a geographic location. A likelihood of conversion is determined based, at least in part, on the spatial information, temporal information and/or the geographic…

    The present disclosure relates to a system and method for determining advertising conversion metrics. In some implementations, a method includes receiving spatial information associated with a user in connection with an advertisement presented through a wireless device. The advertisement is associated with an offline store having a geographic location. A likelihood of conversion is determined based, at least in part, on the spatial information, temporal information and/or the geographic location of the offline store.

    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

    See patent

Languages

  • Chinese

    Native or bilingual proficiency

  • English

    Full professional proficiency

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