The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
Wei Wei - One of the best experts on this subject based on the ideXlab platform.
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network performance of smart mobile handhelds in a university campus wifi network
Internet Measurement Conference, 2012Co-Authors: Xian Chen, Bing Wang, Kyoungwon Suh, Ruofan Jin, Wei WeiAbstract:Smart mobile handheld devices (MHDs) such as smartphones have been used for a wide range of applications. Despite the recent flurry of research on various aspects of smart MHDs, little is known about their network performance in WiFi networks. In this paper, we measure the network performance of smart MHDs inside a university campus WiFi network, and identify the dominant factors that affect the network performance. Specifically, we analyze 2.9TB of data collected over three days by a monitor that is located at a Gateway Router of the network, and make the following findings: (1) Compared to non-handheld devices (NHDs), MHDs use well provisioned Akamai and Google servers more heavily, which boosts the overall network performance of MHDs. Furthermore, MHD flows, particularly short flows, benefit from the large initial congestion window that has been adopted by Akamai and Google servers. (2) MHDs tend to have larger local delays inside the WiFi network and are more adversely affected by the number of concurrent flows. (3) Earlier versions of Android OS (before 4.X) cannot take advantage of the large initial congestion window adopted by many servers. On the other hand, the large receive window adopted by iOS is not fully utilized by most flows, potentially leading to waste of resources. (4) Some application-level protocols cause inefficient use of network and operating system resources of MHDs in WiFi networks. Our observations provide valuable insights on content distribution, server provisioning, MHD system design, and application-level protocol design.
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Passive online wireless LAN health monitoring from a single measurement point
ACM SIGMOBILE Mobile Computing and Communications Review, 2011Co-Authors: Xian Chen, Bing Wang, Kyoungwon Suh, Wei WeiAbstract:Wireless LANs that are deployed in corporations and university campuses can contain a large number of access points and wireless hosts. In this paper, we develop a scalable approach that relies on measurements collected by a single monitor for WLAN health monitoring. We propose two metrics, local RTT and local loss rate, that indicate whether a wireless host experiences performance degradations inside a WLAN, and both can be obtained from measurements at the single monitor. Preliminary evaluation through data collected by a monitor at a university Gateway Router demonstrates the effectiveness of these two metrics.
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Passive Online Rogue Access Point Detection Using Sequential Hypothesis Testing with TCP ACK-Pairs ∗ ABSTRACT
2008Co-Authors: Wei Wei, Kyoungwon Suh, Jim KuroseAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-accesspoint detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76 % of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment)
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passive online rogue access point detection using sequential hypothesis testing with tcp ack pairs
Internet Measurement Conference, 2007Co-Authors: Wei Wei, Kyoungwon Suh, Bing Wang, Jim Kurose, Don TowsleyAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-access-point detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76% of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment).
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Internet Measurement Comference - Passive online rogue access point detection using sequential hypothesis testing with TCP ACK-pairs
Proceedings of the 7th ACM SIGCOMM conference on Internet measurement - IMC '07, 2007Co-Authors: Wei Wei, Kyoungwon Suh, Bing Wang, Jim Kurose, Don TowsleyAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-access-point detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76% of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment).
Kyoungwon Suh - One of the best experts on this subject based on the ideXlab platform.
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network performance of smart mobile handhelds in a university campus wifi network
Internet Measurement Conference, 2012Co-Authors: Xian Chen, Bing Wang, Kyoungwon Suh, Ruofan Jin, Wei WeiAbstract:Smart mobile handheld devices (MHDs) such as smartphones have been used for a wide range of applications. Despite the recent flurry of research on various aspects of smart MHDs, little is known about their network performance in WiFi networks. In this paper, we measure the network performance of smart MHDs inside a university campus WiFi network, and identify the dominant factors that affect the network performance. Specifically, we analyze 2.9TB of data collected over three days by a monitor that is located at a Gateway Router of the network, and make the following findings: (1) Compared to non-handheld devices (NHDs), MHDs use well provisioned Akamai and Google servers more heavily, which boosts the overall network performance of MHDs. Furthermore, MHD flows, particularly short flows, benefit from the large initial congestion window that has been adopted by Akamai and Google servers. (2) MHDs tend to have larger local delays inside the WiFi network and are more adversely affected by the number of concurrent flows. (3) Earlier versions of Android OS (before 4.X) cannot take advantage of the large initial congestion window adopted by many servers. On the other hand, the large receive window adopted by iOS is not fully utilized by most flows, potentially leading to waste of resources. (4) Some application-level protocols cause inefficient use of network and operating system resources of MHDs in WiFi networks. Our observations provide valuable insights on content distribution, server provisioning, MHD system design, and application-level protocol design.
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Passive online wireless LAN health monitoring from a single measurement point
ACM SIGMOBILE Mobile Computing and Communications Review, 2011Co-Authors: Xian Chen, Bing Wang, Kyoungwon Suh, Wei WeiAbstract:Wireless LANs that are deployed in corporations and university campuses can contain a large number of access points and wireless hosts. In this paper, we develop a scalable approach that relies on measurements collected by a single monitor for WLAN health monitoring. We propose two metrics, local RTT and local loss rate, that indicate whether a wireless host experiences performance degradations inside a WLAN, and both can be obtained from measurements at the single monitor. Preliminary evaluation through data collected by a monitor at a university Gateway Router demonstrates the effectiveness of these two metrics.
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MobiCom 2010 Poster: Passive Online Wireless LAN Health Monitoring from a Single Measurement Point ∗
2010Co-Authors: Xian Chen, Bing Wang, Kyoungwon SuhAbstract:Wireless LANs that are deployed in corporations and university campuses can contain a large number of access points and wireless hosts. In this paper, we develop a scalable approach that relies on measurements collected by a single monitor for WLAN health monitoring. We propose two metrics, local RTT and local loss rate, that indicate whether a wireless host experiences performance degradations inside a WLAN, and both can be obtained from measurements at the single monitor. Preliminary evaluation through data collected by a monitor at a university Gateway Router demonstrates the effectiveness of these two metrics.
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Passive Online Rogue Access Point Detection Using Sequential Hypothesis Testing with TCP ACK-Pairs ∗ ABSTRACT
2008Co-Authors: Wei Wei, Kyoungwon Suh, Jim KuroseAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-accesspoint detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76 % of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment)
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passive online rogue access point detection using sequential hypothesis testing with tcp ack pairs
Internet Measurement Conference, 2007Co-Authors: Wei Wei, Kyoungwon Suh, Bing Wang, Jim Kurose, Don TowsleyAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-access-point detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76% of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment).
Don Towsley - One of the best experts on this subject based on the ideXlab platform.
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passive online rogue access point detection using sequential hypothesis testing with tcp ack pairs
Internet Measurement Conference, 2007Co-Authors: Wei Wei, Kyoungwon Suh, Bing Wang, Jim Kurose, Don TowsleyAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-access-point detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76% of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment).
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Internet Measurement Comference - Passive online rogue access point detection using sequential hypothesis testing with TCP ACK-pairs
Proceedings of the 7th ACM SIGCOMM conference on Internet measurement - IMC '07, 2007Co-Authors: Wei Wei, Kyoungwon Suh, Bing Wang, Jim Kurose, Don TowsleyAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-access-point detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76% of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment).
Bing Wang - One of the best experts on this subject based on the ideXlab platform.
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network performance of smart mobile handhelds in a university campus wifi network
Internet Measurement Conference, 2012Co-Authors: Xian Chen, Bing Wang, Kyoungwon Suh, Ruofan Jin, Wei WeiAbstract:Smart mobile handheld devices (MHDs) such as smartphones have been used for a wide range of applications. Despite the recent flurry of research on various aspects of smart MHDs, little is known about their network performance in WiFi networks. In this paper, we measure the network performance of smart MHDs inside a university campus WiFi network, and identify the dominant factors that affect the network performance. Specifically, we analyze 2.9TB of data collected over three days by a monitor that is located at a Gateway Router of the network, and make the following findings: (1) Compared to non-handheld devices (NHDs), MHDs use well provisioned Akamai and Google servers more heavily, which boosts the overall network performance of MHDs. Furthermore, MHD flows, particularly short flows, benefit from the large initial congestion window that has been adopted by Akamai and Google servers. (2) MHDs tend to have larger local delays inside the WiFi network and are more adversely affected by the number of concurrent flows. (3) Earlier versions of Android OS (before 4.X) cannot take advantage of the large initial congestion window adopted by many servers. On the other hand, the large receive window adopted by iOS is not fully utilized by most flows, potentially leading to waste of resources. (4) Some application-level protocols cause inefficient use of network and operating system resources of MHDs in WiFi networks. Our observations provide valuable insights on content distribution, server provisioning, MHD system design, and application-level protocol design.
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Passive online wireless LAN health monitoring from a single measurement point
ACM SIGMOBILE Mobile Computing and Communications Review, 2011Co-Authors: Xian Chen, Bing Wang, Kyoungwon Suh, Wei WeiAbstract:Wireless LANs that are deployed in corporations and university campuses can contain a large number of access points and wireless hosts. In this paper, we develop a scalable approach that relies on measurements collected by a single monitor for WLAN health monitoring. We propose two metrics, local RTT and local loss rate, that indicate whether a wireless host experiences performance degradations inside a WLAN, and both can be obtained from measurements at the single monitor. Preliminary evaluation through data collected by a monitor at a university Gateway Router demonstrates the effectiveness of these two metrics.
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MobiCom 2010 Poster: Passive Online Wireless LAN Health Monitoring from a Single Measurement Point ∗
2010Co-Authors: Xian Chen, Bing Wang, Kyoungwon SuhAbstract:Wireless LANs that are deployed in corporations and university campuses can contain a large number of access points and wireless hosts. In this paper, we develop a scalable approach that relies on measurements collected by a single monitor for WLAN health monitoring. We propose two metrics, local RTT and local loss rate, that indicate whether a wireless host experiences performance degradations inside a WLAN, and both can be obtained from measurements at the single monitor. Preliminary evaluation through data collected by a monitor at a university Gateway Router demonstrates the effectiveness of these two metrics.
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passive online rogue access point detection using sequential hypothesis testing with tcp ack pairs
Internet Measurement Conference, 2007Co-Authors: Wei Wei, Kyoungwon Suh, Bing Wang, Jim Kurose, Don TowsleyAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-access-point detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76% of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment).
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Internet Measurement Comference - Passive online rogue access point detection using sequential hypothesis testing with TCP ACK-pairs
Proceedings of the 7th ACM SIGCOMM conference on Internet measurement - IMC '07, 2007Co-Authors: Wei Wei, Kyoungwon Suh, Bing Wang, Jim Kurose, Don TowsleyAbstract:Rogue (unauthorized) wireless access points pose serious security threats to local networks. In this paper, we propose two online algorithms to detect rogue access points using sequential hypothesis tests applied to packet-header data collected passively at a monitoring point. One algorithm requires training sets, while the other does not. Both algorithms extend our earlier TCP ACK-pair technique to differentiate wired and wireless LAN TCP traffic, and exploit the fundamental properties of the 802.11 CSMA/CA MAC protocol and the half duplex nature of wireless channels. Our algorithms make prompt decisions as TCP ACK-pairs are observed, and only incur minimum computation and storage overhead. We have built a system for online rogue-access-point detection using these algorithms and deployed it at a university Gateway Router. Extensive experiments in various scenarios have demonstrated the excellent performance of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false positive and false negative ratios); the algorithm that does not require training detects 60%-76% of the wireless hosts without any false positives; both algorithms are light-weight (with computation and storage overhead well within the capability of commodity equipment).
Debashis Saha - One of the best experts on this subject based on the ideXlab platform.
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Global Gateway-based UMTS/WLAN integration for improved delay performance
International Journal of Parallel Emergent and Distributed Systems, 2010Co-Authors: Sibaram Khara, Iti Saha Mishra, Debashis SahaAbstract:This paper proposes a loose coupling-based integration between universal mobile telecommunication system (UMTS) and wireless local area networks (WLANs) using mobile Internet protocol (MIP)-based vertical handoff between the two networks. In loose coupling, an integrated network must provide home agent (HA) functionality when a UMTS subscriber moves to WLAN. The position of HA effects the performance of an integrated network. If HA is deployed at Gateway GPRS (general packet radio service) support node (GGSN), delay for data as well as control packets increases when both receiving and transmitting mobile stations (MSs) reside in WLAN. Because each packet travels to GGSN through Gi interface, and routed back to WLAN through the same interface. HA can also be deployed in WLAN Internet protocol (IP) network. This improves delay for data packets, but handoff delay from WLAN to UMTS increases because an MS cannot send MIP registration request to HA before the establishment of packet data protocol context in UMTS network. We propose an efficient integration by fixing the position of HA in a global Gateway Router which is deployed in WLAN IP network. The proposed interworking technique reduces packet delay when both sending and receiving MSs are in WLANs. The methods also update location of a user in UMTS as well as WLAN so that he/she is always reachable from each network irrespective of current position. ns-2-Based simulation results show that our new handoff methods reduce handoff delay from UMTS to WLAN by 10% and that from WLAN to UMTS by 18%.
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improving delay performance in umts wlan integrated networks with global Gateway Router
International Conference on Advanced Computing, 2008Co-Authors: Sibaram Khara, Iti Saha Misra, Debashis SahaAbstract:This paper presents efficient methods of vertical handoffs from UMTS to WLAN and vice versa in a loose coupling architecture. When a mobile terminal (MT) moves from UMTS to WLAN, it performs mobile IP (MIP) registration with home agent (HA). Subsequently, HA needs to perform location update signaling with UMTS network to make the MT reachable from UMTS. If HA is deployed at Gateway GPRS support node (GGSN), all incoming packets from the Internet to an MT are routed via GGSN and average packet-delay increases when the MT is in loosely-coupled WLAN. MIP registration is also affected by the traffics between the Internet and UMTS. To avoid this problem, HA can be deployed in WLAN IP network, but handoff delay from WLAN to UMTS will be more because an MT cannot send MIP-registration request to HA before the establishment of PDP context in UMTS network. We propose efficient handoff methods with simple modification in GPRS tunneling protocol (GTP) and HA functionality by placing a global Gateway Router. Our ns-2 based simulation results show that the proposed technique improves MIP registration during handoff from UMTS to WLAN and vice versa. It also provides lower end-to-end packet delay for Internet services when an MT is residing in WLAN.
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Improving Delay Performance in UMTS/WLAN Integrated Networks with Global Gateway Router
2008 16th International Conference on Advanced Computing and Communications, 2008Co-Authors: Sibaram Khara, Iti Saha Misra, Debashis SahaAbstract:This paper presents efficient methods of vertical handoffs from UMTS to WLAN and vice versa in a loose coupling architecture. When a mobile terminal (MT) moves from UMTS to WLAN, it performs mobile IP (MIP) registration with home agent (HA). Subsequently, HA needs to perform location update signaling with UMTS network to make the MT reachable from UMTS. If HA is deployed at Gateway GPRS support node (GGSN), all incoming packets from the Internet to an MT are routed via GGSN and average packet-delay increases when the MT is in loosely-coupled WLAN. MIP registration is also affected by the traffics between the Internet and UMTS. To avoid this problem, HA can be deployed in WLAN IP network, but handoff delay from WLAN to UMTS will be more because an MT cannot send MIP-registration request to HA before the establishment of PDP context in UMTS network. We propose efficient handoff methods with simple modification in GPRS tunneling protocol (GTP) and HA functionality by placing a global Gateway Router. Our ns-2 based simulation results show that the proposed technique improves MIP registration during handoff from UMTS to WLAN and vice versa. It also provides lower end-to-end packet delay for Internet services when an MT is residing in WLAN.