Tam Vu - Academia.edu (original) (raw)

Papers by Tam Vu

IEEE International Conference on Pervasive Computing and Communications, 2011

In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles usi... more In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles using signal strength traces from GSM enabled phones. Existing speed estimation techniques using mobile phone signals can provide longer-term speed averages but cannot track short-term speed variations. Understanding short-term speed variations, however, is important in a variety of traffic engineering applications-for example, it may help distinguish slow speeds due to traffic lights from traffic congestion when collecting real time traffic information. Using mobile phones in such applications is particularly attractive because it can be readily obtained from a large number of vehicles.

International Conference on Distributed Computing Systems, 2012

This paper presents the design and evaluation of a novel distributed shared hosting approach, DMa... more This paper presents the design and evaluation of a novel distributed shared hosting approach, DMap, for managing dynamic identifier to locator mappings in the global Internet. DMap is the foundation for a fast global name resolution service necessary to enable emerging Internet services such as seamless mobility support, content delivery and cloud computing. Our approach distributes identifier to locator mappings amongst Autonomous Systems (ASs) by directly applying K>1 consistent hash functions on the identifier to produce network addresses of the AS gateway routers at which the mapping will be stored. This direct mapping technique leverages the reachability information of the underlying routing mechanism which is already available at the network layer, and achieves low lookup latencies through a single overlay hop without additional maintenance overheads. The proposed DMap technique is described in detail and specific design problems such as address space fragmentation, reducing latency through replication, taking advantage of spatial locality, as well as coping with inconsistent entries are individually addressed. Evaluation results are presented from a large-scale discrete event simulation of the Internet with ∼26,000 ASs using real-world traffic traces from the DIMES repository. The results show that the proposed method evenly balances storage load across the global network while achieving lookup latencies with a mean value of ∼50 ms and 95 th percentile value of ∼100 ms, considered adequate for support of dynamic mobility across the global Internet.

Today's identification and authentication mechanisms for touchscreen-enabled devices are cumberso... more Today's identification and authentication mechanisms for touchscreen-enabled devices are cumbersome and do not support brief usage and device sharing. To address this challenge, this work explores a novel form of "wireless" communication that exploits the capacitive touchscreens which are now used in laptops, phones, and tablets, as a signal receiver. Using a custom built hardware token, in the form of a wearable ring, we show a proof-of-concept system that transmits a user identification code to the mobile device through the touchscreen. This mechanism works without any modification to the hardware or the firmware of the mobile device.

IEEE INFOCOM, 2012

Localization techniques that allow inferring the location of wireless devices directly from recei... more Localization techniques that allow inferring the location of wireless devices directly from received signals have exposed mobile users to new threats. Adversaries can easily collect required information (such as signal strength) from target users, however, techniques securing location information at the physical layer of the wireless communication systems have not received much attention. In this paper, we propose Phantom, a novel approach to allow mobile devices thwart unauthorized adversary's location tracking by creating forged locations. In particular, Phantom leverages cooperation among multiple mobile devices in close vicinity and utilizes synchronized transmissions among those nodes to obfuscate localization efforts of adversary systems. Through an implementation on software-defined radios (GNU Radios) and extensive simulation with real location traces, we see that Phantom can improve location privacy.

Sarnoff Symposium, IEEE, 2012

In this paper, we present the architectural details of Odin Help Engine, a novel social search en... more In this paper, we present the architectural details of Odin Help Engine, a novel social search engine that leverages online social networks and sensing data from mobile devices to find targeted answers for subjective queries and recommendation requests. In Odin, users' queries are routed to those connections in their social network who (i) are most likely to help answer the question and (ii) can do so with a high level of confidence. Specifically, we first apply a link-based latent variable model to infer social relationships between users from their social network data to form a strength-weighted relationship graph. We then infer users' expertise by context mining from social network data as well as from their mobile device sensor data. Lastly we apply pagerank-like algorithm that takes both relationship strength and user expertise into account to find a person that is most likely willing to answer the question posted by the user. We present the general design of the architecture and outline a location-related query example for detailed illustration.

IEEE Conference on Computer Communications Workshops, INFOCOM Wksps, 2012

This paper describes and compares alternative architectures for achieving the functional goals of... more This paper describes and compares alternative architectures for achieving the functional goals of name oriented networking. The CCN (content-centric network) scheme proposed by Van Jacobson is contrasted with hybrid name and address based routing proposed in conjunction with the MobilityFirst (MF) future Internet architecture. In a CCN network, routers forward data directly on content names (such as URNs), achieving elegant and efficient retrieval of content files; the framework can also be extended to other communications services such as VoIP. The MF scheme supports name-based communication services by introducing the concept of a flat 'globally unique identifier (GUID)', which is used as the authoritative header for routing. Further, the GUID is dynamically mapped to one or more topological network addresses using a global name resolution service (GNRS). This leads to a hybrid GUID and network address based routing (HGN) scheme in which routers operate with both flat names (GUIDs) and network addresses, reducing routing table size and overhead at the cost of a fast distributed service for dynamic mapping of names to addresses. Protocol operations for both CCN and HGN are outlined in context of specific services including content retrieval, unicast and mobility. Preliminary evaluations of scalability and performance for both schemes are given using simple analytical models and selected results from Internet-scale simulations for GNRS and BGP.

This work addresses the fundamental problem of distinguishing between a driver and passenger usin... more This work addresses the fundamental problem of distinguishing between a driver and passenger using a mobile phone, which is the critical input to enable numerous safety and interface enhancements. Our detection system leverages the existing car stereo infrastructure, in particular, the speakers and Bluetooth network. Our acoustic approach has the phone send a series of customized high frequency beeps via the car stereo. The beeps are spaced in time across the left, right, and if available, front and rear speakers. After sampling the beeps, we use a sequential change-point detection scheme to time their arrival, and then use a differential approach to estimate the phone's distance from the car's center. From these differences a passenger or driver classification can be made. To validate our approach, we experimented with two kinds of phones and in two different cars. We found that our customized beeps were imperceptible to most users, yet still playable and recordable in both cars. Our customized beeps were also robust to background sounds such as music and wind, and we found the signal processing did not require excessive computational resources. In spite of the cars' heavy multi-path environment, our approach had a classification accuracy of over 90%, and around 95% with some calibrations. We also found we have a low false positive rate, on the order of a few percent.

Workshop on Wireless Mobile Multimedia, 2013

Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an in... more Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an increasingly important usage scenario for future mobile Internet services. Radio technologies such as 3G/4G and WAVE/802.11p now enable vehicles to communicate with each other and connect to the Internet, but there is still the lack of a unifying network protocol architecture for delivery of services across both V2V and V2I modes. The MobilityFirst future Internet architecture, discussed in this paper, is a clean-slate protocol design in which the requirements of untethered nodes and dynamically formed networks are considered from the ground-up, making it particularly suitable for vehicular applications. Here we describe the vehicular networking specific features and protocol design details of the architecture and present evaluation results on performance and scalability.

Proceedings of the 17th annual international conference on Mobile computing and networking - MobiCom '11, 2011

This work addresses the fundamental problem of distinguishing between a driver and passenger usin... more This work addresses the fundamental problem of distinguishing between a driver and passenger using a mobile phone, which is the critical input to enable numerous safety and interface enhancements. Our detection system leverages the existing car stereo infrastructure, in particular, the speakers and Bluetooth network. Our acoustic approach has the phone send a series of customized high frequency beeps via the car stereo. The beeps are spaced in time across the left, right, and if available, front and rear speakers. After sampling the beeps, we use a sequential change-point detection scheme to time their arrival, and then use a differential approach to estimate the phone's distance from the car's center. From these differences a passenger or driver classification can be made. To validate our approach, we experimented with two kinds of phones and in two different cars. We found that our customized beeps were imperceptible to most users, yet still playable and recordable in both cars. Our customized beeps were also robust to background sounds such as music and wind, and we found the signal processing did not require excessive computational resources. In spite of the cars' heavy multi-path environment, our approach had a classification accuracy of over 90%, and around 95% with some calibrations. We also found we have a low false positive rate, on the order of a few percent.

2013 IEEE 14th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM), 2013

Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an in... more Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an increasingly important usage scenario for future mobile Internet services. Radio technologies such as 3G/4G and WAVE/802.11p now enable vehicles to communicate with each other and connect to the Internet, but there is still the lack of a unifying network protocol architecture for delivery of services across both V2V and V2I modes. The MobilityFirst future Internet architecture, discussed in this paper, is a clean-slate protocol design in which the requirements of untethered nodes and dynamically formed networks are considered from the ground-up, making it particularly suitable for vehicular applications. Here we describe the vehicular networking specific features and protocol design details of the architecture and present evaluation results on performance and scalability.

Proceedings of the 10th international conference on Mobile systems, applications, and services - MobiSys '12, 2012

2011 IEEE International Conference on Pervasive Computing and Communications (PerCom), 2011

In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles usi... more In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles using signal strength traces from GSM enabled phones. Existing speed estimation techniques using mobile phone signals can provide longer-term speed averages but cannot track short-term speed variations. Understanding short-term speed variations, however, is important in a variety of traffic engineering applications-for example, it may help distinguish slow speeds due to traffic lights from traffic congestion when collecting real time traffic information. Using mobile phones in such applications is particularly attractive because it can be readily obtained from a large number of vehicles.

2012 Proceedings IEEE INFOCOM Workshops, 2012

This paper describes and compares alternative architectures for achieving the functional goals of... more This paper describes and compares alternative architectures for achieving the functional goals of name oriented networking. The CCN (content-centric network) scheme proposed by Van Jacobson is contrasted with hybrid name and address based routing proposed in conjunction with the MobilityFirst (MF) future Internet architecture. In a CCN network, routers forward data directly on content names (such as URNs), achieving elegant and efficient retrieval of content files; the framework can also be extended to other communications services such as VoIP. The MF scheme supports name-based communication services by introducing the concept of a flat 'globally unique identifier (GUID)', which is used as the authoritative header for routing. Further, the GUID is dynamically mapped to one or more topological network addresses using a global name resolution service (GNRS). This leads to a hybrid GUID and network address based routing (HGN) scheme in which routers operate with both flat names (GUIDs) and network addresses, reducing routing table size and overhead at the cost of a fast distributed service for dynamic mapping of names to addresses. Protocol operations for both CCN and HGN are outlined in context of specific services including content retrieval, unicast and mobility. Preliminary evaluations of scalability and performance for both schemes are given using simple analytical models and selected results from Internet-scale simulations for GNRS and BGP.

2012 Proceedings IEEE INFOCOM, 2012

Localization techniques that allow inferring the location of wireless devices directly from recei... more Localization techniques that allow inferring the location of wireless devices directly from received signals have exposed mobile users to new threats. Adversaries can easily collect required information (such as signal strength) from target users, however, techniques securing location information at the physical layer of the wireless communication systems have not received much attention. In this paper, we propose Phantom , a novel approach to allow mobile devices thwart unauthorized adversary's location tracking by creating forged locations. In particular, Phantom leverages cooperation among multiple mobile devices in close vicinity and utilizes synchronized transmissions among those nodes to obfuscate localization efforts of adversary systems. Through an implementation on software-defined radios (GNU Radios) and extensive simulation with real location traces, we see that Phantom can improve location privacy.

IEEE Transactions on Mobile Computing, 2000

This work addresses the fundamental problem of distinguishing between a driver and passenger usin... more This work addresses the fundamental problem of distinguishing between a driver and passenger using a mobile phone, which is the critical input to enable numerous safety and interface enhancements. Our detection system leverages the existing car stereo infrastructure, in particular, the speakers and Bluetooth network. Our acoustic approach has the phone send a series of customized high frequency beeps via the car stereo. The beeps are spaced in time across the left, right, and if available, front and rear speakers. After sampling the beeps, we use a sequential change-point detection scheme to time their arrival, and then use a differential approach to estimate the phone's distance from the car's center. From these differences a passenger or driver classification can be made. To validate our approach, we experimented with two kinds of phones and in two different cars. We found that our customized beeps were imperceptible to most users, yet still playable and recordable in both cars. Our customized beeps were also robust to background sounds such as music and wind, and we found the signal processing did not require excessive computational resources. In spite of the cars' heavy multipath environment, our approach had a classification accuracy of over 90 percent, and around 95 percent with some calibrations. We also found, we have a low false positive rate, on the order of a few percent.

IEEE Transactions on Mobile Computing, 2000

ABSTRACT As we are surrounded by an ever-larger variety of post-PC devices, the traditional metho... more ABSTRACT As we are surrounded by an ever-larger variety of post-PC devices, the traditional methods for identifying and authenticating users have become cumbersome and time consuming. In this paper, we present a capacitive communication method through which a device can recognize who is interacting with it. This method exploits the capacitive touchscreens, which are now used in laptops, phones, and tablets, as a signal receiver. The signal that identifies the user can be generated by a small transmitter embedded into a ring, watch, or other artifact carried on the human body. We explore two example system designs with a low-power continuous transmitter that communicates through the skin and a signet ring that needs to be touched to the screen. Experiments with our prototype transmitter and tablet receiver show that capacitive communication through a touchscreen is possible, even without hardware or firmware modifications on a receiver. This latter approach imposes severe limits on the data rate, but the rate is sufficient for differentiating users in multiplayer tablet games or parental control applications. Controlled experiments with a signal generator also indicate that future designs may be able to achieve data rates that are useful for providing less obtrusive authentication with similar assurance as PIN codes or swipe patterns commonly used on smartphones today.

IEEE Pervasive Computing, 2000

ABSTRACT Touch-based personal tokens would let devices unobtrusively identify who is interacting ... more ABSTRACT Touch-based personal tokens would let devices unobtrusively identify who is interacting with the device at any given time. Devices could then tailor services to users and control access to sensitive information and online services. The authors present an approach for using a wearable personal token, in the form of a ring, to send an identification code to devices through touch.

As we are surrounded by an ever-larger variety of post-PC devices, the traditional methods for id... more As we are surrounded by an ever-larger variety of post-PC devices, the traditional methods for identifying and authenticating users have become cumbersome and time-consuming. In this paper, we present a capacitive communication method through which a device can recognize who is interacting with it. This method exploits the capacitive touchscreens, which are now used in laptops, phones, and tablets, as a signal receiver. The signal that identifies the user can be generated by a small transmitter embedded into a ring, watch, or other artifact carried on the human body. We explore two example system designs with a low-power continuous transmitter that communicates through the skin and a signet ring that needs to be touched to the screen. Experiments with our prototype transmitter and tablet receiver show that capacitive communication through a touchscreen is possible, even without hardware or firmware modifications on a receiver. This latter approach imposes severe limits on the data rate, but the rate is sufficient for differentiating users in multiplayer tablet games or parental control applications. Controlled experiments with a signal generator also indicate that future designs may be able to achieve datarates that are useful for providing less obtrusive authentication with similar assurance as PIN codes or swipe patterns commonly used on smartphones today.

Empirical studies on FDI and growth in developed countries have yielded conflicting results using... more Empirical studies on FDI and growth in developed countries have yielded conflicting results using crosscountry regressions. We use sectoral data for a group of six country members of the Organization for Economic Cooperation and Development. Our paper is the first to identify the sector-specific impact of FDI on growth in the developed countries. Our results show that FDI might have positive or negative effect on economic growth operating directly and through its interaction with labor. Moreover, we find the effects seem to be very different across countries and economic sectors.

We examine impact of natural disasters on annual output and output growth in Vietnam. Using provi... more We examine impact of natural disasters on annual output and output growth in Vietnam. Using provincial data for primary and secondary industries in Vietnam, we employ the Blundell-Bond System GMM procedure to estimate the impact of disasters on the macroeconomy. Results show that more lethal disasters result in lower output growth but that more costly disasters (in terms of destroyed capital) actually appear to boost the economy in the short-run. This result is consistent with the 'creative destruction' hypothesis that we outline. However we find that disasters have different macroeconomic impact in different geographical regions; and these differences are potentially related to the ability to generate transfers from the central government.

IEEE International Conference on Pervasive Computing and Communications, 2011

In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles usi... more In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles using signal strength traces from GSM enabled phones. Existing speed estimation techniques using mobile phone signals can provide longer-term speed averages but cannot track short-term speed variations. Understanding short-term speed variations, however, is important in a variety of traffic engineering applications-for example, it may help distinguish slow speeds due to traffic lights from traffic congestion when collecting real time traffic information. Using mobile phones in such applications is particularly attractive because it can be readily obtained from a large number of vehicles.

International Conference on Distributed Computing Systems, 2012

This paper presents the design and evaluation of a novel distributed shared hosting approach, DMa... more This paper presents the design and evaluation of a novel distributed shared hosting approach, DMap, for managing dynamic identifier to locator mappings in the global Internet. DMap is the foundation for a fast global name resolution service necessary to enable emerging Internet services such as seamless mobility support, content delivery and cloud computing. Our approach distributes identifier to locator mappings amongst Autonomous Systems (ASs) by directly applying K>1 consistent hash functions on the identifier to produce network addresses of the AS gateway routers at which the mapping will be stored. This direct mapping technique leverages the reachability information of the underlying routing mechanism which is already available at the network layer, and achieves low lookup latencies through a single overlay hop without additional maintenance overheads. The proposed DMap technique is described in detail and specific design problems such as address space fragmentation, reducing latency through replication, taking advantage of spatial locality, as well as coping with inconsistent entries are individually addressed. Evaluation results are presented from a large-scale discrete event simulation of the Internet with ∼26,000 ASs using real-world traffic traces from the DIMES repository. The results show that the proposed method evenly balances storage load across the global network while achieving lookup latencies with a mean value of ∼50 ms and 95 th percentile value of ∼100 ms, considered adequate for support of dynamic mobility across the global Internet.

Today's identification and authentication mechanisms for touchscreen-enabled devices are cumberso... more Today's identification and authentication mechanisms for touchscreen-enabled devices are cumbersome and do not support brief usage and device sharing. To address this challenge, this work explores a novel form of "wireless" communication that exploits the capacitive touchscreens which are now used in laptops, phones, and tablets, as a signal receiver. Using a custom built hardware token, in the form of a wearable ring, we show a proof-of-concept system that transmits a user identification code to the mobile device through the touchscreen. This mechanism works without any modification to the hardware or the firmware of the mobile device.

IEEE INFOCOM, 2012

Localization techniques that allow inferring the location of wireless devices directly from recei... more Localization techniques that allow inferring the location of wireless devices directly from received signals have exposed mobile users to new threats. Adversaries can easily collect required information (such as signal strength) from target users, however, techniques securing location information at the physical layer of the wireless communication systems have not received much attention. In this paper, we propose Phantom, a novel approach to allow mobile devices thwart unauthorized adversary's location tracking by creating forged locations. In particular, Phantom leverages cooperation among multiple mobile devices in close vicinity and utilizes synchronized transmissions among those nodes to obfuscate localization efforts of adversary systems. Through an implementation on software-defined radios (GNU Radios) and extensive simulation with real location traces, we see that Phantom can improve location privacy.

Sarnoff Symposium, IEEE, 2012

In this paper, we present the architectural details of Odin Help Engine, a novel social search en... more In this paper, we present the architectural details of Odin Help Engine, a novel social search engine that leverages online social networks and sensing data from mobile devices to find targeted answers for subjective queries and recommendation requests. In Odin, users' queries are routed to those connections in their social network who (i) are most likely to help answer the question and (ii) can do so with a high level of confidence. Specifically, we first apply a link-based latent variable model to infer social relationships between users from their social network data to form a strength-weighted relationship graph. We then infer users' expertise by context mining from social network data as well as from their mobile device sensor data. Lastly we apply pagerank-like algorithm that takes both relationship strength and user expertise into account to find a person that is most likely willing to answer the question posted by the user. We present the general design of the architecture and outline a location-related query example for detailed illustration.

IEEE Conference on Computer Communications Workshops, INFOCOM Wksps, 2012

This paper describes and compares alternative architectures for achieving the functional goals of... more This paper describes and compares alternative architectures for achieving the functional goals of name oriented networking. The CCN (content-centric network) scheme proposed by Van Jacobson is contrasted with hybrid name and address based routing proposed in conjunction with the MobilityFirst (MF) future Internet architecture. In a CCN network, routers forward data directly on content names (such as URNs), achieving elegant and efficient retrieval of content files; the framework can also be extended to other communications services such as VoIP. The MF scheme supports name-based communication services by introducing the concept of a flat 'globally unique identifier (GUID)', which is used as the authoritative header for routing. Further, the GUID is dynamically mapped to one or more topological network addresses using a global name resolution service (GNRS). This leads to a hybrid GUID and network address based routing (HGN) scheme in which routers operate with both flat names (GUIDs) and network addresses, reducing routing table size and overhead at the cost of a fast distributed service for dynamic mapping of names to addresses. Protocol operations for both CCN and HGN are outlined in context of specific services including content retrieval, unicast and mobility. Preliminary evaluations of scalability and performance for both schemes are given using simple analytical models and selected results from Internet-scale simulations for GNRS and BGP.

This work addresses the fundamental problem of distinguishing between a driver and passenger usin... more This work addresses the fundamental problem of distinguishing between a driver and passenger using a mobile phone, which is the critical input to enable numerous safety and interface enhancements. Our detection system leverages the existing car stereo infrastructure, in particular, the speakers and Bluetooth network. Our acoustic approach has the phone send a series of customized high frequency beeps via the car stereo. The beeps are spaced in time across the left, right, and if available, front and rear speakers. After sampling the beeps, we use a sequential change-point detection scheme to time their arrival, and then use a differential approach to estimate the phone's distance from the car's center. From these differences a passenger or driver classification can be made. To validate our approach, we experimented with two kinds of phones and in two different cars. We found that our customized beeps were imperceptible to most users, yet still playable and recordable in both cars. Our customized beeps were also robust to background sounds such as music and wind, and we found the signal processing did not require excessive computational resources. In spite of the cars' heavy multi-path environment, our approach had a classification accuracy of over 90%, and around 95% with some calibrations. We also found we have a low false positive rate, on the order of a few percent.

Workshop on Wireless Mobile Multimedia, 2013

Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an in... more Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an increasingly important usage scenario for future mobile Internet services. Radio technologies such as 3G/4G and WAVE/802.11p now enable vehicles to communicate with each other and connect to the Internet, but there is still the lack of a unifying network protocol architecture for delivery of services across both V2V and V2I modes. The MobilityFirst future Internet architecture, discussed in this paper, is a clean-slate protocol design in which the requirements of untethered nodes and dynamically formed networks are considered from the ground-up, making it particularly suitable for vehicular applications. Here we describe the vehicular networking specific features and protocol design details of the architecture and present evaluation results on performance and scalability.

Proceedings of the 17th annual international conference on Mobile computing and networking - MobiCom '11, 2011

This work addresses the fundamental problem of distinguishing between a driver and passenger usin... more This work addresses the fundamental problem of distinguishing between a driver and passenger using a mobile phone, which is the critical input to enable numerous safety and interface enhancements. Our detection system leverages the existing car stereo infrastructure, in particular, the speakers and Bluetooth network. Our acoustic approach has the phone send a series of customized high frequency beeps via the car stereo. The beeps are spaced in time across the left, right, and if available, front and rear speakers. After sampling the beeps, we use a sequential change-point detection scheme to time their arrival, and then use a differential approach to estimate the phone's distance from the car's center. From these differences a passenger or driver classification can be made. To validate our approach, we experimented with two kinds of phones and in two different cars. We found that our customized beeps were imperceptible to most users, yet still playable and recordable in both cars. Our customized beeps were also robust to background sounds such as music and wind, and we found the signal processing did not require excessive computational resources. In spite of the cars' heavy multi-path environment, our approach had a classification accuracy of over 90%, and around 95% with some calibrations. We also found we have a low false positive rate, on the order of a few percent.

2013 IEEE 14th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM), 2013

Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an in... more Vehicular networking, both vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), is an increasingly important usage scenario for future mobile Internet services. Radio technologies such as 3G/4G and WAVE/802.11p now enable vehicles to communicate with each other and connect to the Internet, but there is still the lack of a unifying network protocol architecture for delivery of services across both V2V and V2I modes. The MobilityFirst future Internet architecture, discussed in this paper, is a clean-slate protocol design in which the requirements of untethered nodes and dynamically formed networks are considered from the ground-up, making it particularly suitable for vehicular applications. Here we describe the vehicular networking specific features and protocol design details of the architecture and present evaluation results on performance and scalability.

Proceedings of the 10th international conference on Mobile systems, applications, and services - MobiSys '12, 2012

2011 IEEE International Conference on Pervasive Computing and Communications (PerCom), 2011

In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles usi... more In this paper, we consider the problem of tracking fine-grained speeds variations of vehicles using signal strength traces from GSM enabled phones. Existing speed estimation techniques using mobile phone signals can provide longer-term speed averages but cannot track short-term speed variations. Understanding short-term speed variations, however, is important in a variety of traffic engineering applications-for example, it may help distinguish slow speeds due to traffic lights from traffic congestion when collecting real time traffic information. Using mobile phones in such applications is particularly attractive because it can be readily obtained from a large number of vehicles.

2012 Proceedings IEEE INFOCOM Workshops, 2012

This paper describes and compares alternative architectures for achieving the functional goals of... more This paper describes and compares alternative architectures for achieving the functional goals of name oriented networking. The CCN (content-centric network) scheme proposed by Van Jacobson is contrasted with hybrid name and address based routing proposed in conjunction with the MobilityFirst (MF) future Internet architecture. In a CCN network, routers forward data directly on content names (such as URNs), achieving elegant and efficient retrieval of content files; the framework can also be extended to other communications services such as VoIP. The MF scheme supports name-based communication services by introducing the concept of a flat 'globally unique identifier (GUID)', which is used as the authoritative header for routing. Further, the GUID is dynamically mapped to one or more topological network addresses using a global name resolution service (GNRS). This leads to a hybrid GUID and network address based routing (HGN) scheme in which routers operate with both flat names (GUIDs) and network addresses, reducing routing table size and overhead at the cost of a fast distributed service for dynamic mapping of names to addresses. Protocol operations for both CCN and HGN are outlined in context of specific services including content retrieval, unicast and mobility. Preliminary evaluations of scalability and performance for both schemes are given using simple analytical models and selected results from Internet-scale simulations for GNRS and BGP.

2012 Proceedings IEEE INFOCOM, 2012

Localization techniques that allow inferring the location of wireless devices directly from recei... more Localization techniques that allow inferring the location of wireless devices directly from received signals have exposed mobile users to new threats. Adversaries can easily collect required information (such as signal strength) from target users, however, techniques securing location information at the physical layer of the wireless communication systems have not received much attention. In this paper, we propose Phantom , a novel approach to allow mobile devices thwart unauthorized adversary's location tracking by creating forged locations. In particular, Phantom leverages cooperation among multiple mobile devices in close vicinity and utilizes synchronized transmissions among those nodes to obfuscate localization efforts of adversary systems. Through an implementation on software-defined radios (GNU Radios) and extensive simulation with real location traces, we see that Phantom can improve location privacy.

IEEE Transactions on Mobile Computing, 2000

This work addresses the fundamental problem of distinguishing between a driver and passenger usin... more This work addresses the fundamental problem of distinguishing between a driver and passenger using a mobile phone, which is the critical input to enable numerous safety and interface enhancements. Our detection system leverages the existing car stereo infrastructure, in particular, the speakers and Bluetooth network. Our acoustic approach has the phone send a series of customized high frequency beeps via the car stereo. The beeps are spaced in time across the left, right, and if available, front and rear speakers. After sampling the beeps, we use a sequential change-point detection scheme to time their arrival, and then use a differential approach to estimate the phone's distance from the car's center. From these differences a passenger or driver classification can be made. To validate our approach, we experimented with two kinds of phones and in two different cars. We found that our customized beeps were imperceptible to most users, yet still playable and recordable in both cars. Our customized beeps were also robust to background sounds such as music and wind, and we found the signal processing did not require excessive computational resources. In spite of the cars' heavy multipath environment, our approach had a classification accuracy of over 90 percent, and around 95 percent with some calibrations. We also found, we have a low false positive rate, on the order of a few percent.

IEEE Transactions on Mobile Computing, 2000

ABSTRACT As we are surrounded by an ever-larger variety of post-PC devices, the traditional metho... more ABSTRACT As we are surrounded by an ever-larger variety of post-PC devices, the traditional methods for identifying and authenticating users have become cumbersome and time consuming. In this paper, we present a capacitive communication method through which a device can recognize who is interacting with it. This method exploits the capacitive touchscreens, which are now used in laptops, phones, and tablets, as a signal receiver. The signal that identifies the user can be generated by a small transmitter embedded into a ring, watch, or other artifact carried on the human body. We explore two example system designs with a low-power continuous transmitter that communicates through the skin and a signet ring that needs to be touched to the screen. Experiments with our prototype transmitter and tablet receiver show that capacitive communication through a touchscreen is possible, even without hardware or firmware modifications on a receiver. This latter approach imposes severe limits on the data rate, but the rate is sufficient for differentiating users in multiplayer tablet games or parental control applications. Controlled experiments with a signal generator also indicate that future designs may be able to achieve data rates that are useful for providing less obtrusive authentication with similar assurance as PIN codes or swipe patterns commonly used on smartphones today.

IEEE Pervasive Computing, 2000

ABSTRACT Touch-based personal tokens would let devices unobtrusively identify who is interacting ... more ABSTRACT Touch-based personal tokens would let devices unobtrusively identify who is interacting with the device at any given time. Devices could then tailor services to users and control access to sensitive information and online services. The authors present an approach for using a wearable personal token, in the form of a ring, to send an identification code to devices through touch.

As we are surrounded by an ever-larger variety of post-PC devices, the traditional methods for id... more As we are surrounded by an ever-larger variety of post-PC devices, the traditional methods for identifying and authenticating users have become cumbersome and time-consuming. In this paper, we present a capacitive communication method through which a device can recognize who is interacting with it. This method exploits the capacitive touchscreens, which are now used in laptops, phones, and tablets, as a signal receiver. The signal that identifies the user can be generated by a small transmitter embedded into a ring, watch, or other artifact carried on the human body. We explore two example system designs with a low-power continuous transmitter that communicates through the skin and a signet ring that needs to be touched to the screen. Experiments with our prototype transmitter and tablet receiver show that capacitive communication through a touchscreen is possible, even without hardware or firmware modifications on a receiver. This latter approach imposes severe limits on the data rate, but the rate is sufficient for differentiating users in multiplayer tablet games or parental control applications. Controlled experiments with a signal generator also indicate that future designs may be able to achieve datarates that are useful for providing less obtrusive authentication with similar assurance as PIN codes or swipe patterns commonly used on smartphones today.

Empirical studies on FDI and growth in developed countries have yielded conflicting results using... more Empirical studies on FDI and growth in developed countries have yielded conflicting results using crosscountry regressions. We use sectoral data for a group of six country members of the Organization for Economic Cooperation and Development. Our paper is the first to identify the sector-specific impact of FDI on growth in the developed countries. Our results show that FDI might have positive or negative effect on economic growth operating directly and through its interaction with labor. Moreover, we find the effects seem to be very different across countries and economic sectors.

We examine impact of natural disasters on annual output and output growth in Vietnam. Using provi... more We examine impact of natural disasters on annual output and output growth in Vietnam. Using provincial data for primary and secondary industries in Vietnam, we employ the Blundell-Bond System GMM procedure to estimate the impact of disasters on the macroeconomy. Results show that more lethal disasters result in lower output growth but that more costly disasters (in terms of destroyed capital) actually appear to boost the economy in the short-run. This result is consistent with the 'creative destruction' hypothesis that we outline. However we find that disasters have different macroeconomic impact in different geographical regions; and these differences are potentially related to the ability to generate transfers from the central government.