Building identification refers to the recognition of the identity of a building when the building is sighted. With proper identification, additional useful information can be gained, such as the geographical information of the building and facility information within the building based on the recognized identity. However, existing studies related to building identification require additional information such as building images in advance, or have constraints on the types of possible input images. Therefore, we propose an approach that undertakes building identification using a building boundary map and smartphone sensors. Our approach measures the position of the user and the orientation of the user's view using sensors embedded in a smartphone. We find the building sighted by the user by reducing the area of buildings that can exist in the user's orientation in a step-by-step manner. During the validation of our approach, it identified the buildings with accuracy of up to 83.3% despite the inaccuracy of the building boundary map used and the error inherent in the user's position and orientation based on the smartphone.

Video streaming services strive to support high-quality videos at higher resolutions and frame rates to improve the quality of experience (QoE). However, high-quality videos consume considerable amounts of energy on mobile devices. This paper proposes NeuSaver, which reduces the power consumption of mobile devices when streaming videos by applying an adaptive frame rate to each video chunk without compromising the user experience. NeuSaver generates a policy that can determine the appropriate frame rate for each video chunk using reinforcement learning (RL). The RL model automatically learns the policy that optimizes the QoE goals based on previous observations. NeuSaver also uses an asynchronous advantage actor-critic algorithm to reinforce the RL model quickly and robustly. Streaming servers that support NeuSaver preprocess videos into segments with various frame rates, which is similar to the process of creating videos with multiple bit rates in dynamic adaptive streaming over HTTP. NeuSaver utilizes the commonly used H.264 video codec. We evaluated NeuSaver in various experiments and a user study through four video categories along with the previously proposed model. Our experiments showed that NeuSaver effectively reduces the power consumption of mobile devices when streaming video by an average of 16.14% and up to 23.12% while maintaining high QoE.

The existing methods of ransomware detection have limitations. To be specific, static analysis is not effective to obfuscated binaries, while dynamic analysis is usually restricted to a certain platform and often takes tens of minutes. In this paper, we propose a block-level monitoring system to detect potentially malicious cryptographic operations. We carry out statistical analysis to find heuristic rules to distinguish between normal and encrypted blocks. In order to apply the heuristic rule to the filesystem without kernel modification, we adopt Filesystem in Userspace (FUSE) and define our filesystem Rcryptect for real-time detection of cryptographic function. We demonstrate the protection of well-known ransomware and show that various cryptographic functions can be detected with about 13% overhead.

Selective video encryption schemes for battery-powered video devices have been proposed to prevent illegal acquisition of recorded video during transmission. However, the transmission security of conventional schemes is lower than the fully encrypted transmission schemes because a substantial part of the recorded video remains unencrypted including significant metadata for decoding recorded video. In order to address this limitation, we propose a secure video transmission framework that selectively encrypts video metadata and frames on a per packet basis with a consideration of currently available computing power and transmission distance. Evaluation on a testbed demonstrates that the proposed framework provides enhanced video transmission security with less than half of the battery power consumption required by the fully encrypted transmission scheme.

Connectivity is one of the most challenging issues in Wireless Sensor Network (WSN). Connectivity problems in WSN seek to guarantee a satisfactory communication capability where all mobile sensors can connect to a base station via relay nodes in all data gathering events. In this paper, we focus on minimizing the number of relay nodes while ensuring connectivity in Mobile Wireless Sensor Networks. We propose an improved heuristic algorithm named Clustered Steiner Tree Heuristic (CSTH) to solve this problem in two phases. The first phase is Node Anchoring, which utilizes a greedy approach to find anchor points among clusters of mobile sensors. The second phase is called Steiner Relay Placement, in which a Steiner tree-based heuristic is used to minimize the number of relay nodes while maintaining connectivity in each cluster. Experiments were performed to compare CSTH with previous state-of-the-art heuristics for the problem. Results show that our algorithm can significantly improve the number of required relay nodes as well as computation time.

Streaming services gradually support high-quality videos for the better user experience. However, streaming high-quality video on mobile devices consumes a considerable amount of energy. This paper presents the design and prototype of EVSO, which achieves power saving by applying adaptive frame rates to parts of videos with a little degradation of the user experience. EVSO utilizes a novel perceptual similarity measurement method based on human visual perception specialized for a video encoder. We also extend the media presentation description, in which the video content is selected based only on the network bandwidth, to allow for additional consideration of the user's battery status. EVSO's streaming server preprocesses the video into several processed videos according to the similarity intensity of each part of the video and then provides the client with the processed video suitable for the network bandwidth and the battery status of the client's mobile device. The EVSO system was implemented on the commonly used H.264/AVC encoder. We conduct various experiments and a user study with nine videos. Our experimental results show that EVSO effectively reduces the energy consumption when mobile devices uses streaming services by 22% on average and up to 27% while maintaining the quality of the user experience.

Seamless mobility of mobile objects (MOs) such as containers or virtual machines cannot be guaranteed when MOs move across different networks of which the IP address domains are different. In this paper, we propose what is termed the live migration (LM) system and protocol that together provide seamless mobility for MOs connected to the Internet moving across different networks. The components of the LM system are the LM distributed hash table (DHT) system that stores the locator information of MOs and the LM Access Router, cooperating with the DHT system, which supports the mobility of MOs. The LM Access Router inserts the identifier of an MO into a packet and routes the packet to the LM Access Router to which the MO is associated. The LM system does not require modification of the network protocol stack of the host on which an MO is running, and it can support mobility with the IPv4 and IPv6 Internet protocols by introducing LM Access Routers into the network. We implemented the LM system on a testbed and conducted an experiment on the live migration of containers and virtual machines across networks. The findings showed that downtime of the live migration of a container to a host on a different network can enable the seamless live migration of MOs across networks.

Everything can be mobile, from end-hosts to applications. The need for mobility management is rising rapidly due to the increasing number of mobile devices and the advent of new types of mobile object, such as Internet of Things devices, connected vehicles, wearable devices, and virtual machines. In order to support various types of mobility, we propose an integrated and distributed mobility management approach, called Mobility of Everything (MoE). The MoE approach uses an object ID whose value is used to determine a specific edge switch that an object is connected with. In addition, the approach distributes binding information of an object ID and an IP address of edge switch throughout the network. We implement our approach on both an emulation environment and a testbed with software switches. Our evaluation results demonstrate that the MoE approach achieves seamless and scalable handover of end-hosts and applications.

Pairwise testing is an effective combinatorial test case generation approach in which test cases are developed to execute all possible pairwise combinations of system inputs. It can help reduce the number of test cases and save testing time yet still effective in finding defects. However, it is very difficult for practitioners to effectively apply pairwise testing in the real world because of the lack of suitable techniques and guidelines. To redress this situation, this paper conducts a case study of applying pairwise testing to system data derived from real-valued variable inputs. In order to apply pairwise testing to this case study, this paper develops a test procedure and a novel partitioning method to test derived data as a naïve application of the conventional pairwise testing that would produce a huge number of test cases. A comparative evaluation shows that the pairwise testing of the proposed approach is more effective than the random testing with a 12–20% higher fault detection ratio. Based on our experience, guidelines for applying pairwise testing in practice are also presented. Copyright © 2014 John Wiley & Sons, Ltd.

Wireless local area networks (WLANs) can adopt dynamic channel access technologies such as dynamic bandwidth or channel hopping schemes in order to avoid interference for better link quality. However, in dense networks, the dynamic channel access leads to a higher probability of adjacent channel int

In the mobile software ecosystem, a method that finds out the applications that are compatible with the device of an end user is called application-device matching. In the current mobile software environment, the device fragmentation causes substantial degree of inaccuracy in matching applications with devices as the traditional platform-centric method handles only the features of platform vendors without considering the unique feature set of a certain device, such as device-manufacturer's features, resulting in a low accuracy in matching applications and devices. This paper proposes a new matching method that is device-centric, which achieves high accuracy in application-device matching by grouping features of existing devices and then using it as criteria of application-device matching. To demonstrate the performance of our method, we conduct a case study with 22 devices and 10 applications in the Google Android mobile software ecosystem. The result of case study shows our proposed method shows a higher accuracy.

This paper proposes a novel cross-layer packet prioritization scheme that overcomes the limitations of conventional video prioritization schemes for IPTV system. In the conventional schemes, the Extend profile or frame unit is used for prioritization and these incur limited uses of the video prioritization schemes or unreliable transmission of the P-frame and B-frame headers. In order to overcome these limitations, the proposed scheme uses the MPEG-2 system information and the H.264/AVC NAL header information to prioritize the important video packets including the P-frame and B-frame headers. The experimental results using a testbed demonstrated that the proposed scheme has a significant performance enhancement over the conventional video prioritization schemes in terms of packet utilization ratio for video streaming, direct frame loss ratio, and PSNR.

Indoor positioning and tracking services are garnering more attention. Recently, several state-of-the-art localization techniques have been proposed that use radio maps or the sensors readily available on smartphones. This paper presents a localization system called Indoor Localization using Physical maps and smartphone Sensors (ILPS), which is based on a building blueprint database and smartphone sensors. The blueprint database and access points (APs) provide a number of reference points that can be used to acquire the initial position and adjust the user position each time a reference point is detected. The proposed method is implemented on a smartphone and tested in real indoor environments. The experiments with ILPS demonstrate that using a static blueprint will avoid the costly database updates that are usually required in other approaches due to signal attenuation. Furthermore, ILPS performs better than existing work in term of accuracy and effectiveness for indoor localization.

Although 3D video has become popular, streaming over wireless network faces a number of challenges. Due to frequent frame losses in wireless networks, temporal asynchrony occurs and results in serious visual fatigue for viewers. In order to provide better quality of 3D video, this paper proposes a new scheme called the Temporal Synchronization Scheme (TSS) for live 3D video streaming over wireless networks. TSS delivers video frames for the left and right views in the same frame order with the same transmission priority and compensates for frame damage and loss during the decoding phase. In addition, a new metric called the Stereoscopic Temporal Variation Index (STVI) is proposed to measure the degree of temporal asynchrony in 3D video. Subjective assessments demonstrate that STVI is an objective metric for measuring subjective quality. Moreover, our study shows that the proposed scheme results in better 3D video quality than the conventional method in terms of STVI and MOS.

Many challenges and limitations stand in the way of streaming high resolution video content over a wireless network. A shift towards the 60-GHz band is taking place in order to accommodate for current High Definition streaming demands. However, today's Wi-Fi networks are able to provide the necessary bandwidth with the help of compression. In this paper we evaluate the effectiveness of streaming video over wireless LANs using the H.264 codec. Our study shows that streaming HD content wirelessly over 802.11n is a viable option. However, perceptual quality of video is affected by the amount of background traffic and the presence of interfering nodes, i.e., hidden nodes.

A recent proliferation of mobile devices led to immense deployment of WLAN access points (APs). IEEE 802.11 mobile devices periodically perform active background scanning to discover available APs in the vicinity. However, this periodic active scanning imposes unnecessary overhead in a static WLAN environment. This paper addresses this scanning overhead issue of mobile devices in IEEE 802.11 WLANs and proposes a smart scanning method using a motion sensor. Our scheme scans channels only if the signal strength from the associated AP becomes below a specified threshold and a mobile device is moving. The smart scanning suppresses unnecessary periodic background scans. We implemented the smart scanning in a commercial smartphone and evaluated its performance in a real indoor WLAN environment. The experimental and simulation results show that the smart scanning can significantly reduce the scanning overhead, the number of unnecessary handoffs and force disconnections.

Although the latest video codecs such as H.264/AVC, H.264/SVC, and VP8 were developed with network-friendly features, provisioning the quality of video delivery over IEEE 802.11 wireless networks is still challenging because of error-prone medium and random access. This paper evaluates the quality of video delivery using those latest video codecs over IEEE 802.11. Our results show that reduction of coded video data, consideration of the queue size of each Access Category, and the mandatory implementation of error recovery features in H.264/SVC can help provide robust multimedia transmission over IEEE 802.11. In addition, the performance of the latest video codecs is compared via extensive simulation scenarios. Our comparison shows that VP8 achieves good video quality with the basic medium access control techniques of IEEE 802.11, whereas H.264/AVC and H.264/SVC benefit significantly from appropriate mapping schemes between encoded video fragments and IEEE 802.11e Access Categories.

More and more mobile devices, such as smartphones and pad/tab devices, are being used in IEEE 802.11 Wireless LANs (or Wi-Fi). However, mobile users are currently unsatisfied with using Wi-Fi on the move due to large handoff delay. In order to perform fast handoff, this paper proposes a new scheme using a geomagnetic sensor (or a digital compass) embedded in mobile devices. The proposed scheme predicts the direction of movement of a Mobile Station (MS) from the currently associated Access Point (AP) and performs active scanning with a reduced number of channels. The proposed scheme was implemented in Android smartphones and their performance was evaluated in a real indoor WLAN environment. Our test results show that the proposed scheme reduces handoff delay compared to conventional handoff and selective scanning scheme. In addition, the proposed scheme does not require modification to existing APs, which makes it very practical for using real-time multimedia services on current mobile devices.

Variable length messages have been in use for a long time for efficient delivery of information. As there are many different ways, with varying complexity, to utilize message length variability, it is crucial to thoroughly test the capability of the parsers of such messages to ensure that they correctly handle the variability. However, testing techniques for message length variability were developed only in fragments in the past and therefore test developers who are faced with the task of testing variable length messages are left with little guidance or few techniques for handling them systematically. This paper develops an approach for systematic test cases generation for testing the parsers of variable length messages. To do so, we develop taxonomy of message length variabilities, and derive test requirement patterns for them using the taxonomy. Then test requirements for particular protocols can be derived from the patterns. A case study is conducted to show that the proposed taxonomy and the test requirement patterns are effective in deriving test cases for actual protocols. The results showed significant improvement over the conventional approach. It revealed many missed requirements that were not identified with the test requirements developed using the conventional intuition-based approach.

Providing seamless multimedia services to mobile users is one of the important requirements for the current Internet evolution. However, due to the effects of host mobility, it is difficult to achieve seamless QoS guarantees in mobile Internet. Though Next Step In Signaling (NSIS) protocol was recently proposed as an alternative of RSVP, its applicability has not been completely verified particularly in mobile environment. This paper enhances NSIS protocol based on advance resource reservation using layers 2 and 3 complementation for supporting host mobility. Our approach detects a crossover node (CRN) and reserves network resources proactively along the new path which will be used after handoff This significantly reduces the latency of signaling session re-establishment caused by handoff. Only a few modifications are required to the current NSIS protocol for our approach. The experimental results demonstrate that our approach can provide seamless QoS guarantees for multimedia services in mobile Internet.

We propose a new scheme to reduce route discovery latency for reactive routing protocols, named HOp-based adaptive reduction (HOBAR). In the route discovery phase of reactive routing protocols, source nodes spend extra waiting time to get optimal routes after receiving the first route reply. Our scheme appropriately sets this waiting time period depending on the number of hops in the first route reply. Our simulation results show that HOBAR offers fewer hop routes, significantly reduces route discovery latency, and is more scalable in highly loaded and large networks.

The session initiation protocol (SIP), standardized by the IETF, allows participants to establish a session for delivering multimedia streams such as audio and video. However, when it comes to mobile environment, SIP fails to offer seamless real-time multimedia service due to significant handoff delay caused by IP address allocation and session re-establishment. A common disadvantage of the existing approaches is that they require additional network components or considerable interventions of network administrators. In this paper, we propose a fast handoff mechanism for SIP, which employs the cross-layer interworking technique to reduce the handoff delay. The proposed mechanism, called cross-layer fast handoff for SIP (CF-SIP), proactively performs the IP address reservation and SIP session update by using link layer information of underlying wireless networks. Experimental results from our implementation show that CF-SIP can support the real-time multimedia services in wireless/mobile networks with only few modifications to existing networks. The practicability of CF-SIP is also demonstrated through its application to VoIP and H. 263 video streaming.

In this paper, we propose a new mechanism for supporting seamless QoS guarantees in mobile Internet, called selective establishment of pseudo reservations (SEP). SEP addresses the issues of the conventional approaches such as excessive reservation requirements due to establishment of multiple advance reservations. It significantly reduces the number of required advance reservations by employing a movement detection scheme using link-layer functionalities. SEP requires fewer functional and structural changes in the current Internet components and protocols since all enhanced features are integrated into leaf base stations (BSs). Experimental results show that SEP outperforms the conventional approaches such as HMRSVP in reservation session loss and completion rates as the offered load in the network becomes high and the average number of handoffs increases during a reservation session.

This paper presents an automatic test generation and minimization method for testing interoperability of communication protocols such as the asynchronous transfer mode/broadband integrated services digital network (ATM/B-ISDN) signaling protocol and the transmission control protocol (TCP). The method is based on a technique of composing finite-state machines (FSMs). Traditionally, the generation of inputs utilizing FSM was mostly based on sequential test scripting languages and often done manually. Each input is processed on a one-at-a-time basis, which did not allow generating complex scenarios of simultaneous inputs on several interfaces of the system under test (SUT). In practice, there exists the possibility that additional inputs have to be sent to the SUT, while the previous input is still being processed, and/or multiple inputs need to be sent to different interfaces of the SUT at the same time. Our method generates interoperability test cases dealing with these more complex situations. Moreover, it minimizes the number of increased test cases due to the multiple stimuli without jeopardizing transition coverage. Experimental results have shown that compared with the conventional methods, our test generation method generates more interoperability test cases resulting in higher transition coverage (26% higher for TCP and 12% higher for ATM signaling protocol). Also, our test minimization method reduces the interoperability test cases by about 94% in the case of the ATM signaling protocol with the same transition coverage.

Due to its topological generality and flexibility, the k-ary n-cube architecture has been actively researched for various applications. However, the processor allocation problem has not been adequately addressed for the k-ary n-cube architecture, even though it has been studied extensively for hypercubes and meshes. The earlier k-ary n-cube allocation schemes based on conventional slice partitioning suffer from internal fragmentation of processors. In contrast, algorithms based on job-based partitioning alleviate the fragmentation problem but require higher time complexity. This paper proposes a new allocation scheme based on isomorphic partitioning, where the processor space is partitioned into higher dimensional isomorphic subcubes. The proposed scheme minimizes the fragmentation problem and is general in the sense that any size request can be supported and the host architecture need not be isomorphic. Extensive simulation study reveals that the proposed scheme significantly outperforms earlier schemes in terms of mean response time for practical size k-ary and n-cube architectures. The simulation results also show that reduction of external fragmentation is more substantial than internal fragmentation with the proposed scheme.

Supporting mobility in real-time applications such as Internet telephony is in demand as the mobile Internet becomes prevalent. A simple solution is to use Mobile JP in order to provide transparent handoffs to upper layer applications. However, due in part to the Mobile IP's limitations such as triangular routing delay and encapsulation overhead, application-layer solutions for mobile Internet telephony has been developed by extending Session Initiation Protocol (SIP). This work presents experimental results on Internet telephony based on Mobile IP and examines its feasibility by analyzing delay factors and increased network toads. We found that packet size in terms of number of frames per packet is important in optimizing the packet transmission delay and network load without hindering the interactivity in voice conversations. Our major contribution is to give a real experience on voice over Mobile IP and to raise a need of designing delay-aware and/or load-aware scheme for Internet telephony.

A method for testing multi-protocol implementation under test (IUT) with a single test suite has been proposed in the literature. It tests a multi-protocol IUT in an integrated way compared to the conventional method, where a single-layer test method and a single-layer embedded test method are applied, respectively, to the upper layer protocol and to lower layer protocols. However, it did not consider how to generate the test cases automatically but proposed only an approach for the test method. This paper proposes an algorithm called multi-protocol test method (MPTM) for automatic test case generation based on that approach. With the MPTM, a multi-protocol IUT consisting of two protocol layers is modeled as two finite state machines (FSMs), and the relationships between the their transitions are defined as a set of transition relationships, pre-execution and carried-by. The proposed algorithm is implemented and applied to a simplified TCP/IP and B-ISDN signaling/SSCOP (service specific connection-oriented protocol). The MPTM is able to test the multi-protocol IUT even though the interfaces between the protocol layers are not exposed. It also allows the same test coverage as conventional test methods, but with a much smaller number of test cases and operations.