Mun Choon Chan's research while affiliated with National University of Singapore and other places

Publications (160)

Conference Paper
Full-text available
Data center network faults are hard to debug due to their scale and complexity. With the prevalence of hard-to-reproduce transient faults, root-cause analysis of network faults is extremely difficult due to unavailability of historical data, and inability to correlate the distributed data across the network. Often, it is not possible to find the ro...
Preprint
As the use of machine learning (ML) models is becoming increasingly popular in many real-world applications, there are practical challenges that need to be addressed for model maintenance. One such challenge is to 'undo' the effect of a specific subset of dataset used for training a model. This specific subset may contain malicious or adversarial d...
Preprint
p>Networks regularly face various threats and attacks that manifest in their communication traffic. Recent works proposed unsupervised approaches, e.g., using a variational autoencoder, that are not only effective in detecting anomalies in network traffic, but also practical as they do not require ground truth or labeled data. However, the problem...
Preprint
p>Networks regularly face various threats and attacks that manifest in their communication traffic. Recent works proposed unsupervised approaches, e.g., using a variational autoencoder, that are not only effective in detecting anomalies in network traffic, but also practical as they do not require ground truth or labeled data. However, the problem...
Preprint
Collaborative machine learning (ML) is an appealing paradigm to build high-quality ML models by training on the aggregated data from many parties. However, these parties are only willing to share their data when given enough incentives, such as a guaranteed fair reward based on their contributions. This motivates the need for measuring a party's co...
Article
In this paper, we present a short survey of programmable networks starting from pre-Software Defined Networking efforts to the more recent programmable data-plane. In particular, we highlight the benefits of data-plane programmability and present some of the challenges and future research directions.
Preprint
5G presents a unique set of challenges for cellular network architecture. The architecture needs to be versatile in order to handle a variety of use cases. While network slicing has been proposed as a way to provide such versatility, it is also important to ensure that slices do not adversely interfere with each other. In other words, isolation amo...
Conference Paper
Full-text available
**** Dataset published here - https://github.com/JehLeeKR/phishing-madweb/ **** To tackle phishing attacks, recent research works have resorted to the application of machine learning (ML) algorithms, yielding promising results. Often, a binary classification model is trained on labeled datasets of benign and phishing URLs (and contents) obtained v...
Conference Paper
Full-text available
This paper looks into the problem of detecting network anomalies by analyzing NetFlow records. While many previous works have used statistical models and machine learning techniques in a supervised way, such solutions have the limitations that they require large amount of labeled data for training and are unlikely to detect zero-day attacks. Existi...
Conference Paper
Wireless sensor networks have emerged as an important information collection and monitoring tool. The data collected is typically uploaded to a central gateway for processing and analysis. However, the approach of forwarding all the sensed data to a sink for processing is not always practical due to the high communication cost.In this paper, we pre...
Conference Paper
Full-text available
Current implementations of time synchronization protocols (e.g. PTP) in standard industry-grade switches handle the protocol stack in the slow-path (control-plane). With new use cases of in-network computing using programmable switching ASICs, global time-synchronization in the data-plane is very much necessary for supporting distributed applicatio...
Preprint
Full-text available
This paper looks into the problem of detecting network anomalies by analyzing NetFlow records. While many previous works have used statistical models and machine learning techniques in a supervised way, such solutions have the limitations that they require large amount of labeled data for training and are unlikely to detect zero-day attacks. Existi...
Article
Contemporary many-core architectures, such as Adapteva Epiphany and Sunway TaihuLight, employ per-core software-controlled Scratchpad Memory (SPM) rather than caches for better performance-per-watt and predictability. In these architectures, a core is allowed to access its own SPM as well as remote SPMs through the Network-On-Chip (NoC). However, t...
Book
This book constitutes the refereed proceedings of the 10th International Conference on Communication Systems and Networks, COMSNETS 2018, held in Banaglore, India, in January 2018. The 12 revised full papers presented in this book were carefully reviewed and selected from 134 submissions. They cover various topics in networking and communications...
Chapter
Wireless sensor network testbeds are important elements of sensor network/IoT research. The Indriya testbed has been serving the sensor network community for the last 8 years. Researchers from more than a hundred institutions around the world have been actively using the testbed in their work. However, given that Indriya has been deployed for over...
Conference Paper
Many WiFi fingerprint-based indoor localization approaches have been proposed to ease deployment and minimize infrastructure requirement. While researchers have devoted extensive efforts to improving the accuracy of these approaches, the user experience of such deployments in practice is typically far below expectation. One reason that contributes...
Conference Paper
Beacons, the backbone of the physical web and location-based services, are widely used to tag objects and places. However, as a beacon's wireless transmission is limited to a ranging technology, the localization information is only available when the beacon is nearby. In this work, we propose BFound, a navigation and room level localization system...
Article
Full-text available
Devices with integrated Wi-Fi chips broadcast beacons for network connection management purposes. Such information can be captured with inexpensive monitors and used to extract user behavior. To understand the behavior of visitors, we deployed our passive monitoring system---CrowdProbe, in a multi-floor museum for six months. We used a Hidden Marko...
Conference Paper
Microbursts can degrade application performance in datacenters by causing increased latency, jitter and packet loss. The detection of microbursts and identification of the contributing flows is the first step towards mitigating this problem. Unfortunately, microbursts are unpredictable and typically last for 10's or 100's of μs and the high line ra...
Conference Paper
Achieving fast and efficient many-to-many communication is one of the most complex communication problems, especially in wireless systems. A compact form of many-to-many communication in a distributed system has the potential to bring huge benefit to many distributed algorithms and protocols. Many-to-many communication can be implemented as a seque...
Conference Paper
In this paper, we address the fundamental problem of improving the performance of many-to-one and many-to-many communications. Our approach is Time Division Multiple Access (TDMA) based but addresses the limitations of existing TDMA implementations in a novel way. In a nutshell, we combine packets from many senders into a single large packet transm...
Article
While location is one of the most important context information in mobile and pervasive computing, large-scale deployment of indoor localization system remains elusive. In this work, we propose MPiLoc, a multi-floor indoor localization system that utilizes data contributed by smartphone users through participatory sensing for automatic floor plan a...
Article
Synchronous transmission has been exploited recently for accelerating fundamental operations of wireless sensor networks like data dissemination, data collection, and network-wide agreement by an order of magnitude. Although these protocols (e.g., Glossy) have shown to be highly reliable for small packet sizes, the use of large packet sizes coupled...
Article
An effective neighbor discovery service on smartphones is required for many emerging applications—from proximity-based interactions to opportunistic phone-to-phone collaborations. For a smartphone neighbor discovery service to be usable and attractive, it needs to meet two conflicting goals: 1) phones should discover neighbors fast enough (in secon...
Conference Paper
Mobile devices are increasingly becoming the dominant device for Internet access. The network throughput achieved by a mobile device directly affects the performance and user experience. Throughput measurement techniques thus play an important role in predicting expected performance. Measurement techniques that require the transfer of large amounts...
Conference Paper
Full-text available
In this paper, we present an approach to extract social behavior and interaction patterns of mobile users by passively monitoring WiFi probe requests and null data frames that are sent by smartphones for network control/management purposes. By analyzing the temporal and spatial correlations of the Receive Signal Strength Indicators (RSSI) of packet...
Conference Paper
Full-text available
Experimental research in low-power wireless networking lacks a reference benchmark. While other communities such as databases or machine learning have standardized benchmarks, our community still uses ad-hoc setups for its experiments and struggles to provide a fair comparison between communication protocols. Reasons for this include the diversity...
Article
Understanding indoor environment in an automatic way is of great importance to mobile and pervasive computing. In this paper, we present Zeus, a smartphone-based opportunistic sensing system that automatically constructs indoor maps by merging crowdsourced walking trajectories captured through smartphone inertial sensing. Most importantly, widely u...
Article
While cellular interfaces are known to be the main power consumers in smartphones, our measurements reveal that surprisingly, due to cellular tail effect, a substantial ratio of energy drain comes from the low-frequency, low-data-rate background traffic. To reduce cellular tail energy use, existing solutions either require changing application beha...
Conference Paper
In this work, we present an approach to extract social relationship of mobile users by passively monitoring WiFi probe requests. By analyzing the correlations of the Receive Signal Strength of packets from these low rate transmissions, we are able to discover proximity relationships and social interactions among users. We evaluate the system using...
Conference Paper
Time synchronization is an enabling service that allows devices to share a consistent notion of time and thus makes it easier to build efficient and robust collaborative services. However, existing synchronization protocols based on wireless packet transmissions are not energy efficient because powering the radio often consumes a significant fracti...
Article
Fingerprint-based indoor localization has attracted extensive research efforts due to its potential for deployment without extensive infrastructure support. However, the accuracies of these different systems vary and it is difficult to compare and evaluate these systems systematically. In this work, we propose a Gaussian process based approach that...
Conference Paper
While cellular interfaces are known to be main power consumers in smartphones, our measurements reveal that surprisingly, due to cellular tail effect, a substantial ratio of energy drain comes from the low-frequency, low-data-rate background traffic. To reduce cellular tail energy use, existing solutions either require changing application behavior...
Article
Passive indoor localization for smartphones requires no explicit cooperation of the smartphone and enables a new spectrum of applications such as passive user tracking, mobility monitoring, social pattern analysis, etc. However, existing passive localization methods either achieve coarse-grained localization accuracy or require expensive infrastruc...
Article
The ubiquity of the smartphonesmakes them ideal platforms for generating in-situ content. In well-attended events, photos captured by attendees have diverse views that could be subjected to occlusion and abnormal lighting effects that could obscure the view. Such unstructured photo collections also have significant redundancy. Thus, a scene that is...
Article
Proximity-based mobile applications are increasing in popularity. Such apps engage users while in proximity of places of interest (malls, bus stops, restaurants, theatres), but remain closed or unused after the user goes away. Since the number of `places of interest' is constantly growing and can be large, it is impractical to install a large numbe...
Article
Zoomable video streaming refers to a new class of interactive video applications, where users can zoom into a video stream to view a selected region of interest in higher resolutions and pan around to move the region of interest. The zoom and pan effects are typically achieved by breaking the source video into a grid of independently decodable tile...
Article
The proliferation of mobile cameras has popularized social sharing of videos captured at events such as sports matches, art performances, and lectures. Due to bandwidth and energy constraints, it is often not efficient or desirable to upload all captured videos to a server for sharing immediately after capturing. We propose a pull-based, on-demand...
Article
Accelerometer is the predominant sensor used for lowpower context detection on smartphones. Although lowpower, accelerometer is orientation and position-dependent, requires a high sampling rate, and subsequently complex processing and training to achieve good accuracy. We present an alternative approach for context detection using only the smartpho...
Conference Paper
While location is one of the most important context information in mobile and ubiquitous computing, large-scale deployment of indoor localization system remains elusive. In this work, we propose PiLoc, an indoor localization system that utilizes opportunistically sensed data contributed by users. Our system does not require manual calibration, prio...
Conference Paper
While high throughput is the key for a number of important applications of sensor networks, performance of the state-of-the-art approach is often poor in practice. This is because if even one of the channels used in its pipeline is bad, the pipeline stalls and throughput degrades significantly. In this paper, we propose a new protocol called P3 (Pr...
Conference Paper
In this demonstration, we show a radio map construction system that utilizes opportunistically sensed data contributed by users. Our free-of-infrastructure system releases users from tedious site survey and does not require prior knowledge as floor plan. By merging trajectories collected by different users, the system can automatically generate an...
Conference Paper
The mismatch between increasingly large video resolution and constrained screen size of mobile devices has led to the proposal of zoomable video systems based on tiled video. In the current system, a tiled video frame is constructed from multiple tiles in a single resolution stream. In this paper, we explore the perceptual effect of mixed-resolutio...
Article
Understanding how people communicate with one another plays a very important role in many disciplines including social psychology, economics, marketing, and management science. This paper proposes and evaluates SocialWeaver, a sensing service running on smartphones that performs conversation clustering and builds conversation networks automatically...
Conference Paper
Prior work reveals that unfairness in CSMA networks is mainly caused by three asymmetries: (i) information asymmetry; (ii) channel asymmetry; and (iii) rate asymmetry. In this paper, we develop a simple yet accurate analytical model that jointly characterizes all three asymmetric conditions. Our model allows us to estimate the throughput of two con...
Conference Paper
The metrics of information latency and reach ability are widely used for measuring information flow in opportunistic networks. We present an alternative measure that looks at the amount of information updates or changes, which is an important and yet relatively unexplored metric for characterizing opportunistic networks. In this paper, we propose a...
Conference Paper
In this paper, we present an efficient routing algorithm, Plankton, for Delay/Disruptive Tolerant Network (DTN). Plankton utilizes replica control to reduce overhead and contact probability estimates to improve performance. Plankton has two major features. First, it uses a combination of both short-term bursty contacts and long-term association bas...
Conference Paper
It is well-known that the time taken for disseminating a large data object over a wireless sensor network is dominated by the overhead of resolving the contention for the underlying wireless channel. In this paper, we propose a new dissemination protocol called Splash, that eliminates the need for contention resolution by exploiting constructive in...
Conference Paper
Proliferation of mobile devices with video recording capability has lead to a tremendous growth in the amount of user-generated mobile videos. Researchers have embarked on developing new interesting applications and enhancement algorithms for mobile video. There is, however, no standard dataset with videos that could represent characteristics of mo...
Conference Paper
The mismatch between increasingly large video resolution and constrained screen size of mobile devices has led to the proposal of zoomable video systems based on tiled video. In the current system, a tiled video frame is constructed from multiple tiles in a single resolution stream. In this paper, we explore the perceptual effect of mixed-resolutio...
Conference Paper
Full-text available
Mobile device users can now easily capture and socially share video clips in a timely manner by uploading them wirelessly to a server. When attending crowded events, such as an exhibition or the Olympic Games, however, timely sharing of videos becomes difficult due to choking bandwidth in the network infrastructure, preventing like-minded attendees...
Conference Paper
With mobile devices becoming ubiquitous, collaborative applications have become increasingly pervasive. In these applications, there is a strong need to obtain a count of the number of mobile devices present in an area, as it closely approximates the size of the crowd. Ideally, a crowd counting solution should be easy to deploy, scalable, energy ef...
Conference Paper
This paper presents a distributed taxi advisory dispatch system (TADS) that estimates regions where the demand for taxis exceed the supply of free taxis. Taxis are given advisories to move into these regions to ensure a better balance between number of waiting clients and free taxis overall. TADS performs the following tasks: (1) estimates system s...
Conference Paper
Full-text available
Due to their thin size, vivid colors, high contrast and power efficiency, OLED (Organic Light-Emitting Diode) display and its variants such as AMOLED (Active Matrix OLED) displays are increasingly replacing traditional LCD (Liquid Crystal Display) screens in smart phones. However, the power efficiency of OLED screens greatly depends on the luminanc...
Conference Paper
Large-scale failures are commonplace in commodity data centers, the major platforms for Distributed Stream Processing Systems (DSPSs). Yet, most DSPSs can only handle single-node failures. Here, we propose Meteor Shower, a new fault-tolerant DSPS that overcomes large-scale burst failures while improving overall performance. Meteor Shower is based o...
Conference Paper
Full-text available
As the current generation of mobile smartphones become more powerful, they are being used to perform more resource intensive tasks making battery lifetime a major bottle-neck. In this paper, we present a technique called dynamic AoV lookahead for reducing wireless interface power consumption upto 50% while playing a popular, yet resource intensive,...
Article
Full-text available
With the improved processing power, graphic quality and high-speed wireless connection in recent generations of mobile phones, it looks more attractive than ever to introduce networked games on these devices. However, these games consume higher levels of energy. While device features and application resource requirements are rapidly growing, the ba...
Conference Paper
This paper presents Indriya, a large-scale, low-cost wireless sensor network testbed deployed at the National University of Singapore. Indriya uses TelosB devices and it is built on an active-USB infrastructure. The infrastructure acts as a remote programming back-channel and it also supplies electric power to sensor devices. Indriya is designed to...
Article
With the improved processing power, graphic quality and high-speed wireless connection in recent generations of mobile phones, it looks more attractive than ever to introduce networked games on these devices. However, these games consume higher levels of energy. While device features and application resource requirements are rapidly growing, the ba...