Guohong Cao

Pennsylvania State University | Penn State · Department of Computer Science and Engineering

Deep Neural Network (DNN) is becoming adopted for video analytics on mobile devices. To reduce the delay of running DNNs, many mobile devices are equipped with Neural Processing Units (NPU). However, due to the resource limitations of NPU, these DNNs have to be compressed to increase the processing speed at the cost of accuracy. To address the low...

Many mobile applications have been developed to apply deep learning for video analytics. Although these advanced deep learning models can provide us with better results, they also suffer from the high computational overhead which means longer delay and more energy consumption when running on mobile devices. To address this issue, we propose a frame...

Sleep apnea is a sleep disorder in which breathing is briefly and repeatedly interrupted. Polysomnography (PSG) is the standard clinical test for diagnosing sleep apnea. However, it is expensive and time-consuming which requires hospital visits, specialized wearable sensors, professional installations, and long waiting lists. To address this proble...

Video streaming on mobile devices necessitates a balance between a users' Quality of Experience (QoE) and energy consumption. Given large data sizes from video, extensive amounts of battery power are required for downloading, processing, and playing each video segment. However, video quality may suffer drastically in an effort to pursue energy effi...

Computation offloading has been widely used to alleviate the performance and energy limitations of smartphones by sending computationally intensive applications to the cloud. However, mobile devices with poor cellular service quality may incur high communication latency and high energy consumption for offloading, which will reduce the benefits of c...

Respiratory rate and body position are two major physiological parameters in sleep study, and monitoring them during sleep can provide helpful information for health care. In this paper, we present SleepMonitor, a smartwatch based system which leverages the built-in accelerometer to monitor the respiratory rate and body position. To calculate respi...

It is critical to maintain the communication links between important social pairs. However, maintaining the social links between faraway nodes in wireless networks is extremely difficult. Although multi-hop transmission can be used, if two nodes in the routing path are out of the wireless transmission range, a network partition is possible. To addr...

Community detection has received considerable attention because of its applications to many practical problems in mobile networks. However, when considering temporal information associated with a community (i.e., transient community), most existing community detection methods fail due to their aggregation of contact information into a single weight...

The exponential growth of mobile videos has enabled a variety of video crowdsourcing applications. However, existing crowdsourcing approaches require all video files to be uploaded, wasting a large amount of bandwidth since not all crowdsourced videos are useful. Moreover, it is difficult for applications to find desired videos based on user-genera...

In cellular networks, due to practical deployment issues, some areas have good wireless coverage while others may not. This results in significant throughput (service quality) difference between wireless carriers at some locations. We first analyze the factors that affect the service quality and then validate the existence of service quality differ...

Today, many smartphone users are unaware of what applications (apps) they should stop using to prevent their battery from running out quickly. The problem is identifying such apps is hard due to the fact that there exist hundreds of thousands of apps and their impact on the battery is not well understood. We show via extensive measurement studies t...

Most research on incentive mechanism design in crowdsourcing has focused on how to allocate sensing tasks to participants to maximize the social welfare. However, none of them consider the coverage holes created by the uneven distribution of participants. As a result, most participants in some popular areas compete for tasks, while many tasks in un...

In this paper, we investigate how to network smartphones for providing communications in disaster recovery. By bridging the gaps among different kinds of wireless networks, we have designed and implemented a system called TeamPhone, which provides smartphones the capabilities of communications in disaster recovery. Specifically, TeamPhone consists...

Because of cost and resource constraints, sensor nodes do not have a complicated hardware architecture or operating system to protect program safety. Hence, the notorious buffer-overflow vulnerability that has caused numerous Internet worm attacks could also be exploited to attack sensor networks. We call the malicious code that exploits a buffer-o...

Infectious diseases pose a serious threat to public health due to its high infectivity and potentially high mortality. One of the most effective ways to protect people from being infected by these diseases is through vaccination. However, due to various resource constraints, vaccinating all the people in a community is not practical. Therefore, tar...

This paper proposes SymDetector, a smartphone based application to unobtrusively detect the sound-related respiratory symptoms occurred in a user's daily life, including sneeze, cough, sniffle and throat clearing. SymDetector uses the built-in microphone on the smartphone to continuously monitor a user's acoustic data and uses multi-level processes...

The proliferation of mobile devices such as smartphones has enabled participatory sensing systems that collect data from users through their mobile devices and infer useful information from the data. However, users have concerns regarding possible privacy leakage from their data and lack incentives to contribute their data. To effectively motivate...

Vaccination is one of the most effective ways to protect people from being infected by infectious disease. However, it is often impractical to vaccinate all people in a community due to various resource constraints. Therefore, targeted vaccination, which vaccinates a small group of people, is an alternative approach to contain infectious disease sp...

Opportunistic mobile networks consist of mobile devices which are intermittently connected via short-range radios. Forwarding in such networks relies on selecting relays to carry and deliver data to destinations upon opportunistic contacts. Due to the intermittent network connectivity, relays in current forwarding schemes are selected separately in...

Smartphone based web browsing wastes a lot of power when downloading webpages due to the special characteristics of the wireless radio interface. In this paper, we identify these special characteristics, and address power consumption issues through two novel techniques. First, we reorganize the computation sequence of the web browser when loading a...

In mobile opportunistic networks, most existing research focuses on how to choose appropriate relays to carry and forward data. Although relay selection is an important issue, other issues such as finding content from people with the right expertise are also very important since the ultimate goal of using mobile opportunistic network is to provide...

The recent popularization of hand-held mobile devices, such as smartphones, enables the inter-connectivity among mobile users without the support of Internet infrastructure. When mobile users move and contact each other opportunistically, they form a Delay Tolerant Network (DTN), which can be exploited to share data among them. Data replication is...

The emerging of mobile social networks opens opportunities for viral marketing. However, before fully utilizing mobile social networks as a platform for viral marketing, many challenges have to be addressed. In this paper, we address the problem of identifying a small number of individuals through whom the information can be diffused to the network...

Mobile social networks have emerged as a new frontier in the mobile computing research society, and the commonly used social structure (i.e., community) has been exploited to facilitate the design of network protocols and applications, such as data forwarding and worm containment. However, community based approaches may not be accurate when applied...

Recently, there have been proposals to evade censors by using steganography to embed secret messages in images shared on public photo-sharing sites. However, establishing a covert channel in this manner is not straightforward. First, photo-sharing sites often process uploaded images, thus destroying any embedded message. Second, prior work assumes...

In cellular networks, due to practical deployment issues, some areas have good wireless coverage while others may not. This results in significant throughput (service quality) difference between wireless carriers at some locations. Through extensive measurements, we have validated the existence of such service quality difference. Then, through peer...

Photos obtained via crowdsourcing can be used in many critical applications. Due to the limitations of communication bandwidth, storage and processing capability, it is a challenge to transfer the huge amount of crowdsourced photos. To address this problem, we propose a framework, called SmartPhoto, to quantify the quality (utility) of crowdsourced...

Backup paths are widely used in IP networks to protect IP links from failures. However, existing solutions such as the commonly used independent model and Shared Risk Link Group (SRLG) model do not accurately reflect the correlation between IP link failures, and thus may not choose reliable backup paths. We propose a cross-layer approach for minimi...

This chapter describes the motivations for employing the VMP approach to reduce delays and power consumption attributable to web browsing on smartphones. In 3G networks, the bandwidth has significantly increased compared to earlier generations, but opening web pages on smartphones remains slow and consumes significant energy. The current research h...

This chapter presents detailed design of the Virtual Machine-based Proxy (VMP). We first give an overview of the VMP architecture, and then present efficient communication mechanisms based on compression and adaptation techniques. On the proxy side, we present resource management techniques to optimize the performance of the VMs and cloud technique...

We conclude the book in this chapter. Based on our work, we have identified the key reason of the long delays and high power consumption in web browsing, and have presented the Virtual Machine-based Proxy (VMP) to address the problem. Experimental results validate the benefits of the VMP approach. Finally, we point out future research directions.

This chapter describes some related research similar to that appearing in this book. Since much of previous study is dated and designed for general mobile devices rather than modern smartphones, the initial discussion centers on research for conserving mobile devices’ energy. Then, we survey techniques following three different approaches to offloa...

This chapter introduces the technical challenges arising from supporting web browsing on smartphones. For ease of understanding and further discussions, we briefly describe existing techniques on reducing the access delay and power consumption of smartphones. Then, we propose a new architecture, called Virtual Machine-based Proxy (VMP), which aims...

Mobile sensing relies on data contributed by users through their mobile device (e.g., smart phone) to obtain useful information about people and their surroundings. However, users may not want to contribute due to lack of incentives and concerns on possible privacy leakage. To effectively promote user participation, both incentive and privacy issue...

Mobile Social Network (MSN) with diverse connectivity characteristics is a combination of opportunistic network and mobile ad hoc network. Since the major difficulty of data forwarding is the opportunistic part, techniques designed for opportunistic networks are commonly used to forward data in MSNs. However, this may not be the best solution since...

Opportunistic mobile networks consist of mobile devices which are intermittently connected via short-range radios. Forwarding in such networks relies on selecting relays to carry and deliver data to destinations upon opportunistic contacts. Due to the intermittent network connectivity, relays in current forwarding schemes are selected separately in...

The opening of under-utilized spectrum creates an opportunity for unlicensed users to achieve substantial performance improvement through cognitive radio techniques. In cognitive radio ad-hoc networks, with node mobility and low node density, the network topology is highly dynamic and end-to-end connection is hard to maintain. We propose data repli...

In cognitive radio networks, unlicensed users can use under-utilized licensed spectrum to achieve substantial performance improvement. To avoid interference with licensed users, unlicensed users must vacate the spectrum when it is accessed by licensed (primary) users. Since it takes some time for unlicensed users to switch to other available channe...

Cellular networks can provide pervasive data access for smartphones, but also consume lots of energy, because the cellular interface has to stay in high power state for a long time (called long tail problem) after a data transmission. In this paper, we propose to reduce the tail energy by aggregating the data traffic of multiple nodes using their P...

Location-Based Service (LBS) has become a vital part of our daily life. While enjoying the convenience provided by LBS, users may lose privacy since the untrusted LBS server has all the information about users in LBS and it may track them in various ways or release their personal data to third parties. To address the privacy issue, we propose a Dum...

The emerging of mobile social networks opens opportunities for viral marketing. However, before fully utilizing mobile social networks as a platform for viral marketing, many challenges have to be addressed. In this paper, we address the problem of identifying a small number of individuals through whom the information can be diffused to the network...

Cellular networks (e.g., 3G) are currently facing severe traffic overload problems caused by excessive traffic demands. Offloading part of the cellular traffic through other forms of networks, such as Delay Tolerant Networks (DTNs) and WiFi hotspots, is a promising solution. However, since these networks can only provide intermittent connectivity t...

Disruption tolerant networks (DTNs) are characterized by low node density, unpredictable node mobility, and lack of global network information. Most of current research efforts in DTNs focus on data forwarding, but only limited work has been done on providing efficient data access to mobile users. In this paper, we propose a novel approach to suppo...

Schools are known to play a significant role in the spread of influenza. High vaccination coverage can reduce infectious disease spread within schools and the wider community through vaccine-induced immunity in vaccinated individuals and through the indirect effects afforded by herd immunity. In general, herd immunity is greatest when vaccination c...

In this chapter, we evaluate the performance of our VMP approach, and compare it to other approaches under various system settings. We first describe the experimental setup and the web page benchmark used for evaluation. Then, we evaluate the delays and power consumption of web browsing for different approaches. For delay, we consider the effects o...

Community has received considerable attention because of its application to many practical problems in mobile networks. However, when considering temporal information associated with community (i.e., transient community), most existing community detection methods fail due to their aggregation of the contact information into a single weighted or unw...

Aggregate statistics computed from time-series data contributed by individual mobile nodes can be very useful for many mobile sensing applications. Since the data from individual node may be privacy-sensitive, the aggregator should only learn the desired statistics without compromising the privacy of each node. To provide strong privacy guarantee,...

Many practical problems in mobile social networks such as routing, community detection, and social behavior analysis, rely on accurate user contact detection. The frequently used method for detecting user contact is through Bluetooth on smartphones. However, Bluetooth scans consume lots of power. Although increasing the scan duty cycle can reduce t...

Smartphone based web browsing wastes a lot of power when downloading webpages due to the special characteristics of the 3G radio interface. In this paper, we identify these special characteristics, and address power consumption issues through two novel techniques. First, we reorganize the computation sequence of the web browser when loading a webpa...

Disruption Tolerant Networks (DTNs) utilize the mobility of nodes and the opportunistic contacts among nodes for data communications. Due to the limitation in network resources such as contact opportunity and buffer space, DTNs are vulnerable to flood attacks in which attackers send as many packets or packet replicas as possible to the network, in...

For sensor networks deployed to monitor and report real events, event source anonymity is an attractive and critical security property, which unfortunately is also very difficult and expensive to achieve. This is not only because adversaries may attack against sensor source privacy through traffic analysis, but also because sensor networks are very...

Mobility management is a key aspect of designing and evaluating protocols for Mobile Ad Hoc Networks (MANETs). The high mobility of nodes in a MANET constantly causes the network topology to change. Mobility patterns of nodes have a direct effect on fundamental network characteristics, such as path length, neighborhood size, and link stability. Con...

Community detection is an important issue due to its wide use in designing network protocols such as data forwarding in Delay Tolerant Networks (DTN) and worm containment in Online Social Networks (OSN). However, most of the existing community detection algorithms focus on binary networks. Since most networks are weighted such as social networks, D...

Mobile sensing exploits data contributed by mobile users (e.g., via their smart phones) to make sophisticated inferences about people and their surrounding and thus can be applied to environmental monitoring, traffic monitoring and healthcare. However, the large-scale deployment of mobile sensing applications is hindered by the lack of incentives f...

Today's location-sensitive service relies on user's mobile device to determine the current location. This allows malicious users to access a restricted resource or provide bogus alibis by cheating on their locations. To address this issue, we propose A Privacy-Preserving LocAtion proof Updating System (APPLAUS) in which colocated Bluetooth enabled...

Node mobility and end-to-end disconnections in disruption-tolerant networks (DTNs) greatly impair the effectiveness of data forwarding. Although social-based approaches can address the problem, most existing solutions only focus on forwarding data to a single destination. In this paper, we study multicast with single and multiple data items in DTNs...

The proliferation and ever-increasing capabilities of mobile devices such as smart phones give rise to a variety of mobile sensing applications. This paper studies how an untrusted aggregator in mobile sensing can periodically obtain desired statistics over the data contributed by multiple mobile users, without compromising the privacy of each user...

Quickly recovering IP networks from failures is critical to enhancing Internet robustness and availability. Due to their serious impact on network routing, large-scale failures have received increasing attention in recent years. We propose an approach called Reactive Two-phase Rerouting (RTR) for intra-domain routing to quickly recover from large-s...

Backup paths are widely used to protect IP links from failures. Existing solutions such as the commonly used independent and Shared Risk Link Group models do not accurately reflect the correlation between IP link failures, and thus may not choose reliable backup paths. We propose a cross-layer approach for IP link protection. We develop a correlate...

In this paper, we propose an algorithm to efficiently diagnose large-scale clustered failures. The algorithm, Cluster-MAX-COVERAGE (CMC), is based on greedy approach. We address the challenge of determining faults with incomplete symptoms. CMC makes novel use of both positive and negative symptoms to output a hypothesis list with a low number of fa...

Opportunistic mobile networks consist of personal mobile devices which are intermittently connected with each other. Data access can be provided to these devices via cooperative caching without support from the cellular network infrastructure, but only limited research has been done on maintaining the freshness of cached data which may be refreshed...

We consider the problem of diffusing cached content in an intermittently connected mobile network, starting from a given initial configuration to a desirable goal state where all nodes interested in particular contents have a copy of their desired contents. The goal is to minimize the time taken for the diffusion process to terminate at a goal stat...

In disruption tolerant networks (DTNs), selfish or ma-licious nodes may drop received packets. Such routing misbehavior reduces the packet delivery ratio and wastes system resources such as power and bandwidth. Although techniques have been proposed to mitigate routing misbehavior in mobile ad hoc networks, they cannot be directly applied to DTNs b...

In mobile ad hoc networks (MANETs), nodes move freely and link/node failures are common, which leads to frequent network partitions. When a network partition occurs, mobile nodes in one partition are not able to access data hosted by nodes in other partitions, and hence significantly degrade the performance of data access. To deal with this problem...

The opening of under-utilized spectrum creates the opportunity of substantial performance improvement through cognitive radio techniques. However, the real network performance may be limited since unlicensed users must vacate and switch to other available spectrum if the current spectrum is reclaimed by the licensed (primary) users. During the spec...

In many surveillance scenarios, there are some known critical locations where the events of concern are expected to occur. A common goal in such applications is to use sensors to monitor these critical locations with sufficient quality of surveillance within a designated period. However, with limited sensing resources, the coverage and lifetime req...

Multicast has been envisioned to be useful in many smart grid applications such as demand-response, wide area protection , in-substation protection and various operation and control. Since the multicast messages are related to critical control, authentication is necessary to prevent message forgery attacks. In this paper, we first identify the requ...