While opportunistic packet forwarding has been extensively studied in the case of single hop communication, only recently has opportunistic forwarding for multihop networks been explored. One key...
Performance of 802.11b/g in the Interference 1 Limited Regime (2009)
Vinay Sridhara, Hweechul Shin, Stephan Bohacek
Signal to interference plus noise ratio, SINR, is one of the main factors that affects the quality of wireless communication. While the impact of white Gaussian noise on a wireless channel is well...
Interference Mitigating in Wireless Networks Using Prior Knowledge (2009)
Kejing Liu, Stephan Bohacek, Javier Garcia-frias
Abstract — We propose a framework to mitigate the interference in high data rate mobile wireless networking. Interference is a fundamental obstacle to achieve high data rates in wireless...
Abstract: Multiple antennas can dramatically improve the performance communication. It is a design choice as to how the antennas are used and how they improve performance. For example, by...
Stephan Bohacek, Rick Blum, Len Cimini, Larry Greenstein, Alex Haimovich
impact of the timeliness of information on the
Feasibility of Detecting TCP-SYN Scanning at a Backbone router (2009)
Khushboo Shah, Stephan Bohacek, Andre Broido
Abstract — IP address and TCP/UDP port scanning are critical components of many network attacks. Such scanning allows attackers to spread a self-propagating worm or collect detailed information...
João P. Hespanha, Stephan Bohacek, Junsoo Lee, Katia Obraczka, Abhyudai Singh, Yonggang Xu, ...
continuous dynamics continuous dynamics Deterministic Hybrid Systems q(t) ∈ Q={1,2,…} ≡ discrete state x(t) ∈ R n ≡ continuous state reset-maps right-continuous by convention guard...
A Study of TCP Fairness in High-Speed Networks (2008)
Junsoo Lee, João P. Hespanha, Stephan Bohacek
Abstract — Under the TCP congestion control regime, heterogeneous flows, i.e., flows with different round-trip times (RTTs), that share the same bottleneck link will not attain equal portions of...
Stability Issues in Hop-by-Hop Rate Based Congestion Control (2008)
Vishwesh Kulkarni, Stephan Bohacek, M. G. Safonov
Continuous in time uid ow models based on hop-by-hop networks are developed both from a single connection's point of view as well as from the entire networks point of view. Conditions on various...
While opportunistic packet forwarding has been extensively studied in the case of single hop communication, only recently has opportunistic forwarding for multihop networks been explored. One key...
Abstract Selection metrics for multihop cooperative relaying (2008)
Cooperative relaying enables nodes to actively cooperate to deliver packets to their destination. The best-select protocol (BSP) implements a type of cooperative relaying that generalizes single path...
Efficient Paging in Large-Scale Urban Mesh Networks ABSTRACT (2008)
The task of forming a route can be broken into two parts, finding any route to the desired host and refining that route so it is suitable for the conenction. We refer to this first task as paging and...
Modeling Communication Networks With Hybrid Systems (2008)
Junsoo Lee, Stephan Bohacek, João P. Hespanha, Senior Member, Katia Obraczka
Abstract—This paper introduces a general hybrid systems framework to model the flow of traffic in communication networks. The proposed models use averaging to continuously approximate discrete...
Chansook Lim, Stephan Bohacek, João P. Hespanha, Katia Obraczka
Abstract. Path disuptions (due to congestion, link failures, which may in turn happen during normal operation or caused by malicious activity) are frequent occurrences on the Internet. Thus, several...
In multihop wireless networks, the variability of channels results in some paths providing better performance than other paths. While it is well known that some paths are better than others, a...
Stephan Bohacek, João P. Hespanha, Comp Eng, Junsoo Lee
In this paper we present a general hybrid systems modeling framework to describe the flow of traffic in communication networks. To characterize network behavior, these models use averaging to...
A New TCP for Persistent Packet Reordering (2008)
Stephan Bohacek, João P. Hespanha, Senior Member, Junsoo Lee, Chansook Lim, Student Member, ...
Abstract—Most standard implementations of TCP perform poorly when packets are reordered. In this paper, we propose a new version of TCP that maintains high throughput when reordering occurs and...
An optimal approach to mitigation of flooding denial of service attacks is presented. The objective is to minimize effect of the mitigation while protecting the server. The approach relies on routers...
Fair Pricing of Video Transmissions using Best-Effort and Purchased Bandwidth (2008)
A model based approach to bandwidth pricing is developed. The focus is not on how much an ISP should sell bandwidth for, but rather, how much bandwidth a video service provider (VSP) will need to use...
A New TCP for Persistent Packet Reordering (2008)
Stephan Bohacek, João P. Hespanha, Junsoo Lee, Chansook Lim, Katia Obraczka
Abstract — Most standard implementations of TCP perform poorly when packets are reordered. In this paper, we propose a new version of TCP that maintains high throughput when reordering occurs and...
Modeling Communication Networks with Hybrid Systems (2008)
Junsoo Lee, Stephan Bohacek, João P. Hespanha, Senior Member, Katia Obraczka
Abstract — This paper introduces a general hybrid systems framework to model the flow of traffic in communication networks. The proposed models use averaging to continuously approximate discrete...
Submitted to IEEE Network Magazine Capacity Optimization of Mesh Networks (2008)
Interference and collisions greatly limited the throughput of mesh networks that used contention-based MAC protocols such as 802.11. Significantly higher throughput is achievable if transmissions are...
ABSTRACT Performance of Urban Mesh Networks ∗ (2008)
Vinay Sridhara, Jonghyun Kim, Stephan Bohacek
Currently, large-scale deployments of mesh networks are being planned for Philadelphia as well as other cities. The performance of such networks has never been examined through simulation or through...
Stephan Bohacek, João P. Hespanha, Comp Eng, Junsoo Lee
In this paper we present a general hybrid systems modeling framework to describe the flow of traffic in communication networks. To characterize network behavior, these models use averaging to...
Khushboo Shah, Edmond Jonckheere, Stephan Bohacek
Computer network traffic is analyzed via mutual information techniques, implemented using linear and nonlinear canonical correlation analyses, with the specific objective of detecting UDP flooding...
Jo~ao P. Hespanha, Stephan Bohacek
In this paper we determine routing polices for a data transmission network that are robust with respect to attempts of packet interception by an adversary. This problem is formulated as a zero-sum...
LIMITATION ON ACHIEVABLE PERFORMANCE or ACTIVE QUEUE (2007)
Stephan Bohacek, Edmond Jonckheere, Khushboo Shah
Abstract: Traffic properties relevant to Active Queue Management (AQM) and the resulting pole/zeo and Bode limitations are examined. ARX models of TCP are derived from data collected in a fixed...
Dynamic Modeling of Internet tra¢c: Linear versus nonlinear canonical correlation (2007)
Khushboo Shah, Edmond Jonckheere, Stephan Bohacek
The Hypertext Transfer Protocol (HTTP) and the File Transfer Protocol (FTP) are both application-level protocols layered over the Transmission Control Protocol (TCP). HTTP is a request/response...
Realistic mobility simulation of urban mesh networks (2007)
Jonghyun Kim, Vinay Sridhara, Stephan Bohacek
It is a truism that today’s simulations of mobile wireless networks are not realistic. In realistic simulations of urban networks, the mobility of vehicles and pedestrians is greatly influenced by...
Performance of 802.11b/g in the interference limited regime (2007)
Vinay Sridhara, Hweechul Shin, Stephan Bohacek
Abstract — Signal to interference plus noise ratio, SINR, is one of the main factors that affects the quality of wireless communication. While the impact of white Gaussian noise on a wireless...
Stephan Bohacek, João Hespanha, Junsoo Lee, Chansook Lim, Katia Obraczka
Most of today’s Internet routing protocols forward packets of a connection over a single path. This means that, even if redundant resources are available, a single failure (accidental or due to...
Toward tractable computation of the capacity of multihop wireless networks (2007)
By posing the problem of bandwidth allocation as a constrained maximization problem, it is possible to study various features of optimal bandwidth allocation, and hence the capacity of the network....
Realistic propagation simulation of urban mesh networks,” The (2007)
Vinay Sridhara, Stephan Bohacek
Simulation plays an important role in the verification of mobile wireless networking protocols. Recently several cities have either begun deploying or are completing plans to deploy large-scale urban...
Abstract. In the networking research literature, the problem of network utility optimization is often converted to the dual problem which, due to nondifferentiability, is solved with a particular...
Computer Networks 51 (2007) 3392–3412 (2007)
Vinay Sridhara, Stephan Bohacek
Realistic propagation simulation of urban mesh networks q
Dynamic Modeling of Internet Traffic for Intrusion Detection (2007)
Khushboo Shah, Edmond Jonckheere, Stephan Bohacek
Computer network traffic is analyzed via mutual information techniques, implemented using linear and nonlinear canonical correlation analyses, with the specific objective of detecting UDP flooding...
Dynamic Modeling of Internet Traffic for Intrusion Detection (2007)
Khushboo Shah, Edmond Jonckheere, Stephan Bohacek
Computer network traffic is analyzed via mutual information techniques, implemented using linear and nonlinear canonical correlation analyses, with the specific objective of detecting UDP flooding...
Abstract. In the networking research literature, the problem of network utility optimization is often converted to the dual problem which, due to nondifferentiability, is solved with a particular...
Observations and models of time-varying channel gain in crowded areas (2006)
Vinay Sridhara, Hwee-chul Shin, Stephan Bohacek
Abstract — Testbeds are projected to be the next generation of mechanisms for protocol verification and performance validation of wireless networks. One important objective of these testbeds is to...
Realistic simulation of urban mesh networks - part II: Urban propagation (2006)
Jonghyun Kim, Vinay Sridhara, Stephan Bohacek
It is a truism that simulations of mobile wireless networks are not realistic. There has been little effort in developing realistic mobility models. In urban areas, the mobility of vehicles and...
Efficient paging in large-scale urban mesh networks (2006)
The task of forming a route can be broken into two parts, finding any route to the desired host and refining that route so it is suitable for the conenction. We refer to this first task as paging and...
Wireless links a subject to large deviations in quality. While such deviations may result in the failure of routes, it also means that some routes may be substantially better than others. In order to...
Models and methodologies for simulating mobile ad-hoc networks (2005)
Vinay Sridhara, Jonghyun Kim, Stephan Bohacek
It is a truism that simulations of mobile ad hoc networks (MANETs) are not realistic. Today, simulations typically model propagation with either the freespace model or a ”two-ray ” model. Such...
On the predictability of link lifetimes in urban manets (2005)
Stephan Bohacek, Andjela Ilic, Vinay Sridhara
Link lifetime prediction is occurs frequently in MANET routing protocols. For example, in assigning cache timeout values and route durations, routing protocols make implicit predictions of link...
A survey-based mobility model of people for simulation of urban mesh networks (2005)
In this paper a mobility model of people in urban areas for mobile wireless network simulation is presented. Unlike most mobility models found in the literature, this model attempts to provide...
Performance of urban mesh networks (2005)
Vinay Sridhara, Jonghyun Kim, Stephan Bohacek
These day’s large-scale deployments of mesh networks are being planned for Philadelphia as well as other cities. The performance of such networks has never been examined through simulation or...
TCP throughput and timeout – steady state and time-varying dynamics”, Globecom (2004)
Stephan Bohacek, Khushboo Shah
dynamics
The graphical properties of MANETs in urban environments (2004)
Stephan Bohacek, Vinay Sridhara
A large portion of MANET research has focused on free-space environments. In this extended abstract, MANETs in urban environments are investigated. Specifically, the graphical properties of the ad...
On the performance limitation of active queue management (AQM).” Submitted to (2004)
Khushboo Shah, Stephan Bohacek, Edmond Jonckheere
Abstract—Traffic properties relevant to Active Queue Management (AQM) and the resulting pole/zero and Bode limitations are examined. ARX models of TCP are derived from data collectedinafixed...
Signal processing challenges in active queue management (2004)
Stephan Bohacek, Khushboo Shah, Gonzalo R. Arce, Mike Davis
In 1993, the publication of Sally Floyd’s and Van Jacobson’s seminal paper "Random Early Detection Gateways for Congestion Avoidance " [1] marked a new direction in networking...
TCP-PR: TCP for persistent packet reordering (2003)
Stephan Bohacek, João P. Hespanha, Junsoo Lee, Chansook Lim, Katia Obraczka
Most standard implementations of TCP perform poorly when packets are reordered. In this paper, we propose a new version of TCP that maintains high throughput when reordering occurs and yet, when...
The predictability of data network traffic (2003)
Khushboo Shah, Stephan Bohacek, Edmond Jonckheere
The predictably of data network traffic is assessed. Different topologies, types of traffic, and queueing disciplines are studied. Linear and nonlinear AR(MA) models as well as state space, and...
Saddle policies for secure routing in communication networks (2002)
Stephan Bohacek, João P. Hespanha, Katia Obraczka
In this paper we formalize routing in communication networks as a game between the designer of the routing algorithm and an attacker that attempts to intercept packets. By computing saddle-point...
Saddle policies for secure routing in communication networks (2002)
Stephan Bohacek, João P. Hespanha, Katia Obraczka
In this paper we prove that the off-line policies proposed in a previous paper [1] for secure routing in communication networks are actually saddle-point solutions and therefore not overly...
Enhancing security via stochastic routing (2002)
Stephan Bohacek, João P. Hespanha, Katia Obraczka, Junsoo Lee, Chansook Lim
Abstract—Shortest path routing leaves connections at risk of interception and eavesdropping since the path over which data packets travel is fairly predictable and easy to determine. To improve...
Saddle policies for secure routing in communication networks (2002)
Stephan Bohacek, João P. Hespanha, Katia Obraczka
In this paper we formalize routing in communication networks as a game between the designer of the routing algorithm and an attacker that attempts to intercept packets. By computing saddle-point...
Stephan Bohacek, João P. Hespanha, Junsoo Lee, Chansook Lim, Katia Obraczka
Most standard implementations of TCP perform poorly when packets are reordered. In this paper, we propose a new version of TCP that maintains high throughput when reordering occurs and yet, when...
Dynamic Modeling of Internet Traffic for Intrusion Detection (2001)
Khushboo Shah, Edmond Jonckheere, Stephan Bohacek
Computer network traffic is analyzed via mutual information techniques, implemented using linear and nonlinear canonical correlation analyses, with the specific objectiveofdetectingUDPflooding...
Preliminary results in routing games (2001)
João P. Hespanha, Stephan Bohacek
this paper we determine routing polices for a data In network that are robust with respect to transmission of packet interception by an adversary. This attempts is formulated as a zero-sum game...
Analysis of a TCP hybrid model (2001)
Stephan Bohacek, João P. Hespanha, Junsoo Lee, Katia Obraczka
In this paper we use hybrid systems to model and analyze the transient and steady-state behavior of multiple TCP flows that share a single common bottleneck link. The main contributions of this paper...
Analysis of a TCP hybrid model (2001)
Stephan Bohacek, Joao P. Hespanha, Junsoo Lee, Katia Obraczka
In this paper we use hybrid systems to model and analyze the transient and steady-state behavior of multiple TCP flows that share a single common bottleneck link. The main contributions of this paper...
A Hybrid Systems Framework for TCP Congestion Control (2001)
Stephan Bohacek, João P. Hespanha, Junsoo Lee, Katia Obraczka
Abstract — In this paper we make use of hybrid systems to model the transient and steady-state behavior of multiple TCP flows that share a single common bottleneck link. The contributions of our...
Analysis of a TCP hybrid model (2001)
Stephan Bohacek, João P. Hespanha, Junsoo Lee, Katia Obraczka
In this paper we use hybrid systems to model and analyze the transient and steady-state behavior of multiple TCP flows that share a single common bottleneck link. The main contributions of this paper...
Selection Metrics for Cooperative Multihop Relaying (1970)
Cooperative relaying enables nodes to actively cooperate to deliver packets to their destination. The bestselect protocol (BSP) implements a type of cooperative relaying that generalizes single path...