Yong Huang

Bio: Yong Huang is an academic researcher from University of Massachusetts Amherst. The author has contributed to research in topics: TCP acceleration & Wireless network. The author has an hindex of 3, co-authored 4 publications receiving 125 citations.

TCP Performance in Coded Wireless Mesh Networks

Abstract: This paper investigates the benefit of network coding for TCP traffic in a wireless mesh network. We implement network coding in a real 802.11a wireless mesh network and measure TCP throughput in such a network. Unlike previous implementations of network coding in mesh networks, we use off-the-shelf hardware and software and do not modify TCP or the underlying MAC protocol. Therefore, our implementation can be easily exported to any operational wireless mesh network with minimal modifications. Furthermore, the TCP throughput improvement reported in this paper is due solely to network coding and is orthogonal to other improvements that can be achieved by optimizing other system components such as the MAC protocol. We conduct extensive measurements to understand the relation between TCP throughput and network coding in different mesh topologies. We show that network coding not only reduces the number of transmissions by sending multiple packets via a single transmission but also results in a smaller loss probability due to reduced contention on the wireless medium. Unfortunately, due to asynchronous packet transmissions, there is often little opportunity to code resulting in small throughput gains. Coding opportunity can be increased by inducing small delays at intermediate nodes. However, this extra delay at intermediate nodes results in longer round-trip-times that adversely affect TCP throughput. Through experimentation, we find a delay in the range of 1 ms to 2 ms to maximize TCP throughput. For the topologies considered in this paper, network coding improves TCP throughput by 10% to 85%.

Exploiting the IPID field to infer network path and end-system characteristics

Abstract: In both active and passive network Internet measurements, the IP packet has a number of important header fields that have played key roles in past measurement efforts, e.g., IP source/destination address, protocol, TTL, port, and sequence number/acknowledgment. The 16-bit identification field (IPID) has only recently been studied to determine what information it might yield for network measurement and performance characterization purposes. We explore several new uses of the IPID field, including how it can be used to infer: (a) the amount of internal (local) traffic generated by a server; (b) the number of servers in a large-scale, load-balanced server complex and; (c) the difference between one-way delays of two machines to a target computer. We illustrate and validate the use of these techniques through empirical measurement studies.

Two-level stochastic fluid tandem queuing model for burst impact analysis

Abstract: Queuing analysis is important in providing guiding principles for packet network analysis. Stochastic fluid queueing models have been widely used as burst scale models for high speed communication networks. In this paper, we propose a novel two-level Markov on-off source model to model the burstiness of a packet stream at different time scales. Analytical results are obtained to reveal the impact of traffic burstiness at two levels on the queue lengths in a tandem queue system. Our method combines the modeling power of the Poisson processes with that of stochastic differential equations to handle the complex interactions between the packet arrivals and the queue content. Our results for the tandem queuing network could be used to further justify the packet spacing scheme in helping deploying small buffer routers.

MCMSDA: a multi-channel multi-sector directional antenna wireless LAN

Abstract: Recently there is an increasing interest in using directional antennas and multi-channel for ad-hoc wireless networks. The two techniques can also be used for infrastructure local area networks. In this paper, we present the architecture and the MAC layer design for a multi-channel multi-sector directional antenna wireless local area network (MCMSDA WLAN). This paper has three key components. First, we describe the network architecture and propose a TDMA-based MAC layer. Second, we formulate the channel time allocation problem as an optimization problem and introduce a Lagrangian relaxation based load-balancing algorithm as a solution. The simulation study shows that the algorithm obtains good sub-optimal solution very quickly. Finally, we propose two methods to accelerate the load-balancing process further.

The devil and packet trace anonymization

Abstract: Releasing network measurement data---including packet traces---to the research community is a virtuous activity that promotes solid research. However, in practice, releasing anonymized packet traces for public use entails many more vexing considerations than just the usual notion of how to scramble IP addresses to preserve privacy. Publishing traces requires carefully balancing the security needs of the organization providing the trace with the research usefulness of the anonymized trace. In this paper we recount our experiences in (i) securing permission from a large site to release packet header traces of the site's internal traffic, (ii) implementing the corresponding anonymization policy, and (iii) validating its correctness. We present a general tool, tcpmkpub, for anonymizing traces, discuss the process used to determine the particular anonymization policy, and describe the use of metadata accompanying the traces to provide insight into features that have been obfuscated by anonymization

Defending against hitlist worms using network address space randomization

Abstract: Worms are self-replicating malicious programs that represent a major security threat for the Internet, as they can infect and damage a large number of vulnerable hosts at timescales where human responses are unlikely to be effective. Sophisticated worms that use precomputed hitlists of vulnerable targets are especially hard to contain, since they are harder to detect, and spread at rates where even automated defenses may not be able to react in a timely fashion.This paper examines a new proactive defense mechanism called Network Address Space Randomization (NASR) whose objective is to harden networks specifically against hitlist worms. The idea behind NASR is that hitlist information could be rendered stale if nodes are forced to frequently change their IP addresses. NASR limits or slows down hitlist worms and forces them to exhibit features that make them easier to contain at the perimeter. We explore the design space for NASR and present a prototype implementation as well as preliminary experiments examining the effectiveness and limitations of the approach.

FMTCP: a fountain code-based multipath transmission control protocol

Abstract: Ideally, the throughput of a Multipath TCP (MPTCP) connection should be as high as that of multiple disjoint single-path TCP flows. In reality, the throughput of MPTCP is far lower than expected. In this paper, we conduct an extensive simulation-based study on this phenomenon, and the results indicate that a subflow experiencing high delay and loss severely affects the performance of other subflows, thus becoming the bottleneck of the MPTCP connection and significantly degrading the aggregate goodput. To tackle this problem, we propose Fountain code-based Multipath TCP (FMTCP), which effectively mitigates the negative impact of the heterogeneity of different paths. FMTCP takes advantage of the random nature of the fountain code to flexibly transmit encoded symbols from the same or different data blocks over different subflows. Moreover, we design a data allocation algorithm based on the expected packet arriving time and decoding demand to coordinate the transmissions of different subflows. Quantitative analyses are provided to show the benefit of FMTCP. We also evaluate the performance of FMTCP through ns-2 simulations and demonstrate that FMTCP outperforms IETF-MPTCP, a typical MPTCP approach, when the paths have diverse loss and delay in terms of higher total goodput, lower delay, and jitter. In addition, FMTCP achieves high stability under abrupt changes of path quality.

Network Coding Meets Multimedia: A Review

Abstract: While every network node only relays messages in a traditional communication system, the recent network coding (NC) paradigm proposes to implement simple in-network processing with packet combinations in the nodes. NC extends the concept of “encoding” a message beyond source coding (for compression) and channel coding (for protection against errors and losses). It has been shown to increase network throughput compared to traditional networks implementation, to reduce delay and to provide robustness to transmission errors and network dynamics. These features are so appealing for multimedia applications that they have spurred a large research effort towards the development of multimedia-specific NC techniques. This paper reviews the recent work in NC for multimedia applications and focuses on the techniques that fill the gap between NC theory and practical applications. It outlines the benefits of NC and presents the open challenges in this area. The paper initially focuses on multimedia-specific aspects of network coding, in particular delay, in-network error control, and media-specific error control. These aspects permit to handle varying network conditions as well as client heterogeneity, which are critical to the design and deployment of multimedia systems. After introducing these general concepts, the paper reviews in detail two applications that lend themselves naturally to NC via the cooperation and broadcast models, namely peer-to-peer multimedia streaming and wireless networking.