Because mobile users demand a high quality and energy-friendly video delivery service that efficiently uses wireless resources, we introduce an energy-efficient video delivery system by applying moving route navigation and playout buffer control based on the mobile throughput history data. The proposed system first determines the optimal travel route to achieve high-speed and energy-efficient communications. Then when a user enters a high throughput area, our system temporarily extends the video playout buffer size, and the user aggressively downloads video segments via a high-speed and energy-efficient wireless connection until the extended buffer is filled. After leaving this area, the user consumes video segments from the extended buffer in order to keep smooth video playback without wireless communications. We carry out computer simulations, laboratory and field experiments and confirm that the proposed system can achieve energy-efficient mobile video delivery.

Operations, such as text entry and zooming, are simple and frequently used on mobile touch devices. However, these operations are far from being perfectly supported. In this paper, we present our prototype, BackAssist, which takes advantage of back-of-device input to augment front-of-device touch interaction. Furthermore, we present the results of a user study to evaluate whether users can master the back-of-device control of BackAssist or not. The results show that the back-of-device control can be easily grasped and used by ordinary smart phone users. Finally, we present two BackAssist supported applications - a virtual keyboard application and a map application. Users who tried out the two applications give positive feedback to the BackAssist supported augmentation.

Network function virtualization improves the flexibility of infrastructure resource allocation but the application of commodity facilities arouses new challenges for systematic reliability. To meet the carrier-class reliability demanded from the 5G mobile core, several studies have tackled backup schemes for the virtual network function deployment. However, the existing backup schemes usually sacrifice the efficiency of resource allocation and prevent the sharing of infrastructure resources. To solve the dilemma of balancing the high level demands of reliability and resource allocation in mobile networks, this paper proposes an approach for the problem of pooling deployment of virtualized network functions in virtual EPC network. First, taking pooling of VNFs into account, we design a virtual network topology for virtual EPC. Second, a node-splitting algorithm is proposed to make best use of substrate network resources. Finally, we realize the dynamic adjustment of pooling across different domains. Compared to the conventional virtual topology design and mapping method (JTDM), this approach can achieve fine-grained management and overall scheduling of node resources; guarantee systematic reliability and optimize global view of network. It is proven by a network topology instance provided by SNDlib that the approach can reduce total resource cost of the virtual network and increase the ratio of request acceptance while satisfy the high-demand reliability of the system.

An accurate but energy-efficient estimation of a position is important as the number of mobile computing systems grow rapidly. A challenge is to develop a highly accurate but energy efficient estimation method. A particle filter is a key algorithm to estimate and track the position of an object which exhibits non-linear movement behavior. However, it requires high usage of computation resources and energy. In this paper, we propose a scheme which can dynamically adjust the number of particles according to the accuracy of the reference signal for positioning and reduce the energy consumption by 37% on Cortex A7.

The intermediate frequency-over-fiber (IFoF) technology has attracted attention as an alternative transmission scheme to the functional split for the next-generation mobile fronthaul links due to its high spectral efficiency and perfect centralized control ability. In this paper, we discuss and clarify network architectures suited for IFoF, based on its advantages over the functional split. One of the major problems for IFoF transmission is dispersion-induced RF power fading, which limits capacity and transmission distance. We introduce our previous work, in which high-capacity and long-distance IFoF transmission was demonstrated by utilizing a parallel intensity/phase modulators (IM/PM) transmitter which can effectively avoid the fading. The IFoF technology with the proposed scheme is well suited for the long-distance mobile fronthaul links for the 5th generation (5G) mobile system and beyond.

Mobile cloud computing (MCC) has been proposed as a new approach to enhance mobile device performance via computation offloading. The growth in cloud computing energy consumption is placing pressure on both the environment and cloud operators. In this paper, we focus on energy-efficient resource management in MCC and aim to reduce cloud operators' energy consumption through resource management. We establish a deterministic resource management model by solving a combinatorial optimization problem with constraints. To obtain the resource management strategy in deterministic scenarios, we propose a deterministic strategy algorithm based on the adaptive group genetic algorithm (AGGA). Wireless networks are used to connect to the cloud in MCC, which causes uncertainty in resource management in MCC. Based on the deterministic model, we establish a stochastic model that involves a stochastic optimization problem with chance constraints. To solve this problem, we propose a stochastic strategy algorithm based on Monte Carlo simulation and AGGA. Experiments show that our deterministic strategy algorithm obtains approximate optimal solutions with low algorithmic complexity with respect to the problem size, and our stochastic strategy algorithm saves more energy than other algorithms while satisfying the chance constraints.

We propose a time synchronization technique for mobile base stations (BSs) by distributing the reference time information from one optical network unit (ONU) to the BSs under different ONUs over Time Division Multiplexing Passive Optical Network (TDM-PON) using common Precision Time Protocol (PTP). The time accuracy, long term time stability and time source switchover functionality for redundancy are confirmed by experimental verification. Furthermore, an interoperability test between a 10G-EPON prototype in which the proposed protocol is implemented and a commercial Time Division Long Term Evolution (TD-LTE) BS is successfully demonstrated obtaining time error within 119ns, which is much less than the criterion value of 1.5µs, for 60 hours.

We propose an algorithm for the gathering problem of mobile agents in arbitrary networks (graphs) with Byzantine agents. Our algorithm can make all correct agents meet at a single node in O(fm) time (f is the upper bound of the number of Byzantine agents and m is the number of edges) under the assumption that agents have unique ID and behave synchronously, each node is equipped with an authenticated whiteboard, and f is known to agents. Here, the whiteboard is a node memory where agents can leave information. Since the existing algorithm achieves gathering without a whiteboard in Õ(n9λ) time, where n is the number of nodes and λ is the length of the longest ID, our algorithm shows an authenticated whiteboard can significantly reduce the time for the gathering problem in Byzantine environments.

In this paper, we propose a Mobile Edge Internet of Things (MEIoT) architecture by leveraging the fiber-wireless access technology, the cloudlet concept, and the software defined networking framework. The MEIoT architecture brings computing and storage resources close to Internet of Things (IoT) devices in order to speed up IoT data sharing and analytics. Specifically, the IoT devices (belonging to the same user) are associated to a specific proxy Virtual Machine (VM) in the nearby cloudlet. The proxy VM stores and analyzes the IoT data (generated by its IoT devices) in real-time. Moreover, we introduce the semantic and social IoT technology in the context of MEIoT to solve the interoperability and inefficient access control problem in the IoT system. In addition, we propose two dynamic proxy VM migration methods to minimize the end-to-end delay between proxy VMs and their IoT devices and to minimize the total on-grid energy consumption of the cloudlets, respectively. Performance of the proposed methods is validated via extensive simulations.

With the rapid increase in demand for mobile data, mobile network operators are trying to expand wireless network capacity by deploying wireless local area network (LAN) hotspots on which they can offload their mobile traffic. However, these network-centric methods usually do not fulfill the interests of mobile users (MUs). Taking into consideration many issues, MUs should be able to decide whether to offload their traffic to a complementary wireless LAN. Our previous work studied single-flow wireless LAN offloading from a MU's perspective by considering delay-tolerance of traffic, monetary cost and energy consumption. In this paper, we study the multi-flow mobile data offloading problem from a MU's perspective in which a MU has multiple applications to download data simultaneously from remote servers, and different applications' data have different deadlines. We formulate the wireless LAN offloading problem as a finite-horizon discrete-time Markov decision process (MDP) and establish an optimal policy by a dynamic programming based algorithm. Since the time complexity of the dynamic programming based offloading algorithm is still high, we propose a low time complexity heuristic offloading algorithm with performance sacrifice. Extensive simulations are conducted to validate our proposed offloading algorithms.

In mobile phone systems, the 4th generation is widely prevailing in 2017, and in 2020, it is expected that the 5th generation (5G) will start to prevail. In both generations, a linear power amplifier (PA) is used. In case of 4G, in addition, such as the envelope tracking (ET) and the digital predistortion (DPD) systems are applied to improve efficiency and linearity. In case of 5G, because of wider modulation band width and parallel operation under the multiple-input and multiple output (MIMO) mode, it might be difficult to apply all systems as those of 4G. Therefore linear PA for 5G will require higher performance with standalone operation. The linear amplifier, in spite of its name, operates non-linearly. In this paper, the non-linear operations of the linear amplifier and their effects on the linearity characteristics are reviewed. After that, impacts of non-linear elements of a hetero junction bipolar transistor (HBT), by analyzing single stage amplifier, are stated. In addition, major PA architectures including ET and DPD systems are reviewed.

This paper proposes a painterly morphing algorithm for mobile smart devices, where each frame in the morphing sequence looks like an oil-painted picture with brush strokes. It can be presented, for example, during the transition between the main screen and a specific application screen. For this, a novel dissimilarity function and acceleration data structures are developed. The experimental results show that the algorithm produces visually stunning effects at an interactive time.

Internet of Things (IoT) devices deployed in urban areas are seen as data sources for urban sensing IoT applications. Since installing cellular interfaces on a huge number of IoT devices is expensive, we propose to use a user equipment (UE) device with a local wireless interface as a mobile IoT gateway for fixed IoT devices. In this paper, we design a new mobile architecture based on cellular networks to accommodate non-cellular fixed IoT devices by UE devices working as IoT gateways. One key feature is that our architecture leverages proximity services (ProSe) to discover relay UE devices with low overhead in terms of discovery messages. Through simulation studies, we clarify the feasibility of our architecture including the relay UE discovery mechanism in urban areas.

The Helmholtz-Kohlraush effect is a visual characteristic that humans perceive color having higher saturation as brighter. In the proposed method, the pixel value is reduced by increasing the saturation while maintaining the hue and value of HSV color space, resulting in power saving of OLED displays since the power consumption of OLED displays directly depends on the pixel value. Although the luminance decreases, brightness of image is maintained by the Helmholtz-Kohlraush effect. In order to suppress excessive increase of saturation, the increase factor of saturation is reduced with an increase in brightness. As maximum increase factor of saturation, kMAX, increases, more power is reduced but unpleasant color change takes place. From the subjective evaluation experiment with the 23 test images consisting of skin, natural and non-natural images, it is found that kMAX is less than 2.0 to suppress the unpleasant color change. When kMAX is 2.0, the power saving is 8.0%. The effectiveness of the proposed technique is confirmed by using a smart phone having 4.5 inches diagonal RGB AMOLED display.

In order to support seamless mobility in the Information-Centric Networking (ICN) Architecture we propose the Named-Node Network Architecture (3NA). 3NA introduces two independent namespaces to ICN, the 3N namespace used to uniquely identify nodes within a network and the Point of Attachment (PoA) namespace to identify a node's PoA to the network. The mappings between the two namespaces, along with all the necessary mechanisms to keep the mappings updated over time, are used when routing ICN packets to improve delay and the goodput when either the producer or the consumer are mobile. To support simultaneous producer and consumer mobility, we expand on the 3NA by adding a new Protocol Data Unit (PDU), the DU PDU. The DU PDU permits the encapsulation of ICN packets in a header that has source and destination name fields which belong to 3NA's 3N namespace. The new PDU permits seamless connectivity as long as 3NA's point of attachment signaling is strictly followed. We demonstrate the performance of the DU PDU against our previous defined communication methods and Named Data Networking's (NDN) Smart Flooding forwarding strategy using our open source nnnSIM module for the ns-3 framework. The new PDU outperforms all existing alternatives when the producer or both consumer and provider are mobile, obtaining overall lower mean network delay and higher median goodput.

Smart education environment, that is a learning environment utilizing the Information Communication Technology (ICT), has attracted a great deal of attention. In order to expand this environment, we need a system that can establish the learning environment armed cloud systems to reduce a significant strain on teaching staff. The important issue for such system is extensibility because the system should be adapted to many kinds of original digital learning material with minimum modification. Therefore, this paper proposes “An Application Framework for Smart Education System: SES Framework”. In this Smart Education System, multi-aspect information concerning to a technical term embedded in the original digital learning material can be retrieved from different social media automatically. They can be also displayed on multi-screen devices according to user's operation. It is implemented based on “Transforming Model” which enables the migration of the original digital learning material to the smart education environment. It also has an easy operation flow for trainees named “three-step selection flow”. SES Framework derived from Model-View-Controller (MVC) pattern is based on the system architecture that enables triple mashup against the original digital learning material, external social media, and screen devices in front of users. All these functionalities have been implemented on cloud systems. We show SES Framework through the implementation example. We also demonstrate the effectiveness of SES Framework by indicating the system modification case study.

This paper describes optical access networks focusing on passive optical network (PON) technologies from a technical point of view. Optical access networks have been applied to fiber-to-the-home as a driving force of broadband services and their use will continue growing in the near future. They will be applied as an aggregate component of broadband wireless networks. This paper also addresses solutions for their application.

This paper discusses key technologies specific for fifth generation (5G) cellular systems which are expected to connect internet of things (IoT) based vertical sectors. Because services for 5G will be expanded drastically, from information transfer services to mission critical and massive connection IoT connection services for vertical sectors, and requirement for cellular systems becomes quite different compared to that of fourth generation (4G) systems, after explanation for the service and technical trends for 5G, key wireless access technologies will be discussed, especially, from the view point of what is new and how import. In addition to the introduction of new technologies for wireless access, flexibility of networking is also discussed because it can cope with QoS support services, especially to cope with end-to-end latency constraint conditions. Therefore, this paper also discuss flexible network configuration using mobile edge computing (MEC) based on software defined network (SDN) and network slicing.

The cloud radio access network (C-RAN) is embracing unprecedented popularity in the evolution of current RAN towards 5G. One of the essential benefits of C-RAN is facilitating cooperative transmission to enhance capacity and energy performances. In this paper, we argue that the conventional symmetric coordination in which all antennas participate in transmission does not necessarily lead to an energy efficient C-RAN. Further, the current assessments of energy consumption should be modified to match this shifted paradigm in network architecture. Towards this end, this paper proposes an asymmetric coordination scheme to optimize the energy efficiency of C-RAN. Specifically, asymmetric coordination is approximated and formulated as a joint antenna selection and power allocation problem, which is then solved by a proposed sequential-iterative algorithm. A modular power consumption model is also developed to convert the computational complexity of coordination into baseband power consumption. Simulations verify the performance benefits of our proposed asymmetric coordination in effectively enhancing system energy efficiency.

Android is one of the most popular mobile device platforms. However, since Android apps can be disassembled easily, attackers inject additional advertisements or malicious codes to the original apps and redistribute them. There are a non-negligible number of such repackaged apps. We generally call those malicious repackaged apps “clones.” However, there are apps that are not clones but are similar to each other. We call such apps “relatives.” In this work, we developed a framework called APPraiser that extracts similar apps and classifies them into clones and relatives from the large dataset. We used the APPraiser framework to study over 1.3 million apps collected from both official and third-party marketplaces. Our extensive analysis revealed the following findings: In the official marketplace, 79% of similar apps were attributed to relatives, while in the third-party marketplace, 50% of similar apps were attributed to clones. The majority of relatives are apps developed by prolific developers in both marketplaces. We also found that in the third-party market, of the clones that were originally published in the official market, 76% of them are malware.