Challenges for Hardware Reliability in Networked Embedded Systems

The massive growth of data consumption and the variety of wireless technology emergence has made the handover (HO) an attractive research topic nowadays, mainly due to the popularity of Wireless Local Area Networks (WLANs), which allow users to reach high-speed data communication while they are in movement. Moreover, mobile devices such as tablets and smartphones have also become increasingly popular due to their low cost and ease of use, and an increase in mobile device use is expected to accelerate in the coming years, along with the availability and use of applications such as real-time services and online gaming. The traditional HO methods will likely not meet the requirements of mobile devices for modern applications due to the lack of intelligence, lack of awareness Quality of Service (QoS) and Quality of Experience (QoE) requirements of mobile users. We, therefore, introduce a novel architecture that supports horizontal HO in homogenous networks. This architecture is based on the Software-Defined Wireless Networking (SDWN) concept, where the wireless network is controlled centrally and the wireless Access Points (APs) are programmable. In this architecture, HO algorithms will assist wireless users to find the network that could best support the application requirements through Quality of Service (QoS) and Quality of Experience (QoE) management policies. The first HO algorithm proposed in this thesis is called Quality of Experience Oriented Handover Algorithm. This algorithm will guarantee the best possible connectivity to the users in terms of their QoE and QoS requirements and outperforms the traditional methods in a sparse network environment. The second contribution is called Optimised Handover Algorithm for Dense WLAN Environments. This algorithm has been designed to address dense network environments via taking into consideration the Adaptive Hysteresis Value (AHV). The AHV will help the Optimised Handover Algorithm via reducing the so-called ping-pong effect. This contribution shows promising performance results by selecting the best candidate AP, decreasing the number of redundant HO and avoiding the ping-pong effect. The final contribution is called Priority Based Handover Algorithm. We extended our proposed SDWN architecture in order to include the concept of prioritising users and make a smart decision during the process of HO. This algorithm will prioritise a certain class of users to avoid the effect of the over-congestion. The results show that the approach based on priority outperforms the state of the art and provides better QoE to the high priority users despite the over-congestion situation.

Bandwidth is a scarce and variable resource in all types of wireless networks. Tracking the available bandwidth and having all applications using the wireless channel adapt their quality of service (QoS) to the available bandwidth is a complex procedure. It requires several adjustments at each layer of the OSI protocol stack. Moreover, the procedures at each layer of the stack must co-operatively interact with those at the other to ensure maximum satisfaction for users.

Energy conservation in battery powered mobile devices that perform wireless multimedia streaming has been a significant research problem since last decade. This is because these mobile devices consume a lot of power while receiving, decoding and ultimately, presenting the multimedia content. What makes things worse is the fact that battery technologies have not evolved enough to keep up with the rapid advancement of mobile devices. This survey examines solutions that have been proposed during the last few years, to improve the energy efficiency of wireless multimedia streaming in mobile hand-held devices. We categorize the research work according to different layers of the Internet protocol stack they utilize. Then, we again regroup these studies based on different traffic scheduling and multimedia content adaptation mechanisms. The traffic scheduling category contains those solutions that optimize the wireless receiving energy without changing the actual multimedia content. The second category on the other hand, specifically modifies the content, in order to reduce the energy consumed by the wireless receiver and to decode and view the content. We compare them and provide evidence of the fact that some of these tactics already exist in modern smaprtphones and provide energy savings with real measurements. In addition, we discuss some relevant literature on the complementary problem of energy-aware multimedia delivery from mobile devices and contrast with our target approaches for multimedia transmission to mobile devices.

Aims: This research aims to secure and support mobile devices and IoTs enabled in WLAN and 5G Multi-Access Edge Computing (MEC) infrastructures. Background: Currently, wireless network access gains increasing potential in today's networks. At the same time, such ongoing wireless network access also raises the risk of network attacks. The 5G technology is expected to empower people inter-communications by integrating wireless networking technologies in all kinds of networks. Additionally, the emerging 5G technologies put forward many new requirements for RF characteristics and techniques regarding bandwidth and power issues, in addition to supporting high connectivity capacity for the emerging IP-based IoT applications. Objective: The objective is to provide a hybrid architecture of the proposed framework for a 5G network with cloudlet computing. The purpose that we are focusing on it is to support and monitor wireless networks under attack. Methods: The solution is done through a hybrid architecture. In this architecture, the cloudlet and Wi-Fi access points (AP) are integrated for providing an integrated Wi-Fi-enabled cloudlet. On the other hand, we have specified a solution for detecting unauthorized APs by using authentication and authorization techniques for securing communications among endpoint devices such as IoT devices or mobile devices, cloudlet, and the main cloud. A framework of this architecture has been developed to face the issue of securing IoT devices and mobile wireless devices. Results: The traffic sniffing and traffic filtering of the endpoints are done. Therefore, the required actions that define the organization's policy are applied through the permitted access list. In addition to a wireless network location, the management components use more than one authorized attribute value to generate the authorized list, such as SSID, MAC, BSSID …etc. Finally, Traffic analysis provides the user to get reports, statistics, and analysis charts of secure endpoints activities. Conclusion: We are focusing on one of the critical security issues of wireless networks. Namely, the issue of unauthorized access becomes more critical due to getting access to a network without subscriber permission. Moreover, the proposed solution allows managing access control permissions to allow or block access to resources for the user of a mobile device.

Building a high-performance microprocessor presents many reliability challenges. Designers must verify the correctness of large complex systems and construct implementations that work reliably in varied (and occasionally adverse) operating conditions. To further complicate this task, deep submicron fabrication technologies present new reliability challenges in the form of degraded signal quality and logic failures caused by natural radiation interference. In this paper, we introduce dynamic verification, a novel microarchitectural technique that can significantly reduce the burden of correctness in microprocessor designs. The approach works by augmenting the commit phase of the processor pipeline with a functional checker unit. The functional checker verifies the correctness of the core processor's computation, only permitting correct results to commit. Overall design cost can be dramatically reduced because designers need only verify the correctness of the checker unit. We detail the DIVA checker architecture, a design optimized for simplicity and low cost. Using detailed timing simulation, we show that even resource-frugal DIVA checkers have little impact on core processor performance. To make the case for reduced verification costs, we argue that the DIVA checker should lend itself to functional and electrical verification better than a complex core processor. Finally, future applications that leverage dynamic verification to increase processor performance and availability are suggested.

This paper presents a seamless high-quality HTTP adaptive streaming algorithm that considers wireless network conditions and the energy consumption of a mobile device with networking cost constraints over heterogeneous wireless networks . In the proposed algorithm, the requested video segments are concurrently delivered through multiple wireless networks to overcome the limitations of a single network. The segment quality level, number of requested segments, network inactive interval, and amount of requested data through each wireless network are determined adaptively in order to provide a seamless high-quality video with low energy consumption and networking cost constraints at the mobile device. The proposed algorithm is fully implemented in an Android-based mobile device and tested in an actual wireless network environment.

Grid computing using wireless networks is receiving increasing attention and is expected to become a critical part of future grid computing. However, the inherent challenges of mobile environments such as mobility management, disconnected operation, device heterogeneity, service discovery, and resource sharing are significant issues in mobile grid computing. To achieve the best performance in a mobile grid computing environment, the mobile devices with the lowest probability of mobility should be selected for use first. We therefore focus on the idle state of mobile devices and use IP-paging scheme to identify the idle mobile devices. For this, we propose a user-defined checkpoint technique for task migration, which is based on the information of when a mobile device will leave the network or stop due to low battery. Our checkpoint technique performs checkpoints by two conditions: when a mobile device leaves its current cell and when it turns off due to low battery capacity.KeywordsMobile GridIP-PagingTask MigrationCheckpoints

In this paper, we describe GREENET (an early stage training network in enabling technologies for green radio), which is a new project recently funded by the European Commission under the auspices of the 2010 Marie Curie People Programme. Through the recruitment and personalized training of 17 Early Stage Researchers (ESRs), in GREENET we are committed to the development of new disruptive technologies to address all aspects of energy efficiency in wireless networks, from the user devices to the core network infrastructure, along with the ways the devices and equipment interact with one another. Novel techniques at the physical, link, and network layers to reduce the energy consumption and carbon footprint of 4G devices will be investigated, such as Spatial Modulation (SM) for Multiple-Input-Multiple-Output (MIMO) systems, Cooperative Automatic Repeat reQuest (C-ARQ) protocols, and Network Coding (NC) for lossy networks. Furthermore, cooperation and cognition paradigms will be exploited as additional assets to improve the energy efficiency of wireless networks with the challenging but indispensable constraint of optimizing the system capacity without degrading the user's Quality-of-Service (QoS).

This paper analyzes troubles detected during the early stages of research projects conducted by postgraduate junior researchers in the field of Fine Arts. Due to the effort involved in delimiting, defining and developing the object to be analyzed, choosing the research topic appears to be one of the main problems. Our students are not familiar with the early stages of the research due to a restrictive understanding of the creation process. A fact that works against the specification and delimitation of the topic to be investigated, which is detrimental to the understanding of the critical capacity of artistic language as well as it hinders the systematization of their creative processes, among other questions. Their lack of experience causes the confrontation of the artistic creation and the theoretical research, and this prevents them to relate the themes of interest, and prompts these themes to remain detached from their creative concerns. The aim of this work is not only to clarify the development of these early stages of theoretical research but to make them understand that these issues are also addressed within the artistic creation process.

Recent demands on affordable, portable wireless communication and computation devices have resulted in exponential growth of wireless networks ranging from Wireless Local Area Networks (WLAN) and Wireless Wide Area Networks (WWAN) to Ad-Hoc and Sensor networks. The major goal of wireless communication is to allow users to communicate together and to have access to global network anytime anywhere. This has led to wide acceptance of infrastructure based cellular networks (WWANs) where mobile stations communicate with a centralized controller, often referred as Access Point (AP) that is connected to the wired networks. On the other hand, WLANs have appeared as dominant popular technologies in many venues including a local area such as an academic campus or an airport terminal. These wireless networks mostly rely on IEEE 802.11 Wi-Fi (Wireless Fidelity) technology and its various derived versions (i.e. 802.11a,b,g). IEEE 802.11 standard supports two operational modes: The infrastructure-based Wireless Local Area Networks (WLANs) and an infrastructure-less Ad-Hoc Networks. A WLAN (Conti, 2003) typically imposes the existence of an AP and normally is connected to the wired networks to provide internet access for mobile devices. Obviously, only one hop link is needed to communicate between mobile devices and AP. In contrast, there is no AP or infrastructure in Ad-Hoc networks. Any two stations can communicate directly when they are in the range of reception of each other. To this end, the stations may use multi-hop routing to deliver their packets to destinations. The ad-hoc protocols (Conti, 2003; Mohapatra & Krishnamurthy, 2005) are self-configured for address and routing in the face of mobility and the network topology may change in each configuration. The multi-hop wireless ad-hoc networks, or multi-hop wireless networks enable wireless networking in the environments where the wired or cellular connections are impossible, inadequate, or cost effective (e.g. battle field, disaster recovery, etc.). The popularity of internet over the last decades has resulted in rapid advancement of demanding applications. The Transmission Control Protocol/Internet Protocol (TCP/IP) (Stevens, 1994) is a well-known de facto protocol in developing today’s internet. Basically, TCP provides a connection-oriented and reliable end-to-end data delivery between two hosts in traditional wired networks. Since TCP is well tuned and due to its wide acceptance in internet, it is desirable to extend and adopt its functionality to wireless networks. On the

The author describes an introductory graduate course on mobile and wireless networks and applications at Stanford University. This course has achieved notable success in combining research and education. The course focuses on how the mobility of users and devices affects networks, systems, and applications. The course considers mobility's influence on multiple layers of the protocol stack, from medium access control to applications. The course also considers systems issues such as security and privacy, file systems, resource discovery, resource management including energy, and personal online identities.

The image of a license plate is scanned by the camera attached to a mobile PDA device and the numbers on the plate are detected by the image processing parts in the proposed Mobile system. Then the numbers and the location of a mobile PDA device are encoded and transmitted along with the location information to a remote server through a wireless communication network. Finally, the server decodes the transmitted data as a text format and transmits it to the destination user. Consequently, this paper contributes a case study on the embedded system for designing of intelligent interface between a moving vehicle and a mobile PDA device, using a spatial relative distance scheme. The experimental results show that detection and tracking of a location of moving vehicle can be conducted efficiently with a mobile PDA device in real-time through wireless communication system and Internet.

Nowadays, mobile devices, such as smartphones, tablets or smartwatches, are essential items in our daily life. Further, more and more people use smart mobile devices in their everyday work for remote controlling, observing diagrams, performing web analytics, etc. However, the full potential of mobile devices is not tapped yet; built-in sensors such as accelerometers or gyroscopes offer a wide range of interaction capabilities, which are still often not fully used in nowadays mobile applications. On the other hand, desktops are still the dominating working device, but with significantly differing interaction means. With additional hand tracking devices capturing the user's gestures additional input possibilities are available but still often unused. In this paper, we investigate on a concept for orientation-based touch-less interaction. Depending on the type of device - traditional desktop or a mobile device - we use an interaction metaphor called "Waggle"; utilizing of tilting and turning of either the user's hand or the mobile device itself for additional input possibilities. Based on the results of two pilot studies for both environments, basic parameters for future design decisions are derived: on the one hand, the maximum angle for basic rotation axes are evaluated. On the other hand, different discretizations of tilt and turn angles are investigated. Based on the outcome of both studies the optimal configuration for the use of the Waggle interaction metaphor in future applications on both mobile and desktop environments are defined.

The recent development of high-speed data transmission over wireless networks enables multimedia broadcasting service to mobile users. Multimedia broadcasting service involves interactions among different system and network components, so it is crucial for the service provider to verify the correctness of system/service model and design, and their behaviors before a new type of service is deployed. However, due to limitations of using network simulations or scaled experimental testbeds, there has been none of research on such verification and simulation framework in 3G broadcasting networks. Therefore, we propose a simulation and analysis framework for multimedia broadcasting service over wireless networks. With concrete modeling of wireless physical channel, network, and data processing on a client device, it enables the prediction of various interesting system parameters and perceived quality of multimedia streams to users. Different models of system and network components can be plugged easily in our simulation framework for further extensions. Using this framework, we analyze the processing performance for decoding scalable videos on mobile devices in CDMA2000 wireless networks.

Analyzing massive amounts of data using complex machine learning models requires significant computational resources. The conventional approach to such problems involves centralizing training data and inference processes in the cloud, i.e., in data centers. However, with the proliferation of mobile devices and increasing application of the Internet-of-Things (IoT) paradigm, very large amounts of data are collected at the edges of wireless networks, and due to privacy constraints and limited communication resources, it is undesirable or impractical to upload this data from mobile devices to the cloud for centralized learning. This problem can be solved by distributed learning at the network edge, by which edge devices collaboratively train a shared learning model using real-time mobile data. The avoidance of raw-data uploading not only helps to preserve privacy but may also alleviate network-traffic congestion and minimize latency. With that said, distributed training still requires a substantial amount of information exchange between devices and edge servers over wireless links. In the process, wireless impairments such as noise, interference, and imperfect knowledge of channel states can significantly slow down distributed learning (e.g., convergence speed) and degrades its performance (e.g., learning accuracy). This makes it crucial to optimize wireless network performance so as to support the efficient deployment of distributed learning algorithms. On the other hand, distributed learning algorithms provide a powerful tool-set for solving complex problems in wireless communication and networking. One important framework, called federated learning (FL), enables users to collaboratively learn a shared model while helping to preserve local data privacy. The application of FL can endow edge devices with capabilities of user behavior prediction, user identification, and wireless environment analysis. As another example, distributed reinforcement learning is capable of leveraging distributed computation power and data to solve complex optimization and control problems that arise in various use cases, such as network control, user clustering, resource management, and interference alignment. To cover this paradigm of distributed learning over wireless networks, this two-part Special Issue features papers dealing with two main research challenges: a) optimization of wireless network performance for efficient implementation of distributed learning in wireless networks, and b) distributed learning for solving communication problems and optimizing network performance.