IDRA: A flexible system architecture for next generation wireless sensor networks

Wireless sensor networks consist of embedded devices (sensor nodes), equipped with a low-power radio. They are used for many applications: from wireless building automation to e-health applications. However, due to the limited capabilities of sensor nodes, designing network protocols for these constrained devices is currently very challenging. Therefore, this paper presents the IDRA platform: an information driven architecture designed to support next-generation applications on resource constrained networked objects. IDRA supports simple but useful optimizations at an architectural level. These include support for cross-protocol interactions, energy efficiency optimizations, QoS optimizations (packet priorities, dynamic protocol selection), mobility support and heterogeneous network support. The paper shows how the development of protocols is improved by using an architecture which delegates specific tasks to a central system, decreasing the memory requirements of associated network protocols. A thorough experimental performance analysis demonstrates that IDRA is much more scalable in terms of memory requirements, energy requirements and processing overhead than traditional system architectures. Finally, the paper discusses how the optimizations presented in this paper can be used for the clean-slate design of architectures for other wireless or wired network types.     

Metadata-guided evaluation of resource-constrained queries in content caching based wireless networks

Recent years have witnessed the emergence of data-centric storage that provides energy-efficient data dissemination and organization in mobile wireless environments. However, limited resources of wireless devices bring unique challenges to data access and information sharing. To address these challenges, we introduce the concept of content caching networks, in which the collected data will be stored by its contents in a distributed manner, while the data in the network is cached for a certain period of time before it is sent to a centralized storage space for backup. Furthermore, we propose a metadata-guided query evaluation approach to achieve query efficiency in content caching networks. By this approach, each cache node will maintain the metadata that summarizes the data content on itself. Queries will be evaluated first on the metadata before on the cached data. By ensuring that queries will only be evaluated on relevant nodes, the metadata-guided query evaluation approach can dramatically improve the performance of query evaluation. We design efficient algorithms to construct metadata for both numerical and categorical data types. Our theoretical and empirical results both show that our metadata-guided approach can accelerate query evaluation significantly, while achieving the memory requirements on wireless devices.     

Adaptive link layer strategies for energy efficient wireless networking

Low power consumption is a key design metric for portable wireless network devices where battery energy is a limited resource. The resultant energy efficient design problem can be addressed at various levels of system design, and indeed much research has been done for hardware power optimization and power management within a wireless device. However, with the increasing trend towards thin client type wireless devices that rely more and more on network based services, a high fraction of power consumption is being accounted for by the transport of packet data over wireless links [28]. This offers an opportunity to optimize for low power in higher layer network protocols responsible for data communication among multiple wireless devices. Consider the data link protocols that transport bits across the wireless link. While traditionally designed around the conventional metrics of throughput and latency, a proper design offers many opportunities for optimizing the metric most relevant to battery operated devices: the amount of battery energy consumed per useful user level bit transmitted across the wireless link. This includes energy spent in the physical radio transmission process, as well as in computation such as signal processing and error coding. This paper describes how energy efficiency in the wireless data link can be enhanced via adaptive frame length control in concert with adaptive error control based on hybrid FEC (forward error correction) and ARQ (automatic repeat request). Key to this approach is a high degree of adaptivity. The length and error coding of the atomic data unit (frame) going over the air, and the retransmission protocol are (a) selected for each application stream (ATM virtual circuit or IP/RSVP flow) based on quality of service (QoS) requirements, and (b) continually adapted as a function of varying radio channel conditions due to fading and other impairments. We present analysis and simulation results on the battery energy efficiency achieved for user traffic of different QoS requirements, and describe hardware and software implementations.     

Artificial Neural Network Expert System for Integrated Heart Rate Variability

This paper describes the combination of an expert system for bio-information with smart devices using a wireless sensor network. A wireless bio-sensor module acquires physiological signals, including electrocardiogram, heart rate, heart rate variability (HRV) and autonomic nervous system activity. The smart device transmits the bio-information over a wireless network to a real-time expert consultation function for analysis, storage and decision making. An artificial neural network algorithm detects the HRV parameters and examines them for features of diabetes. A centralized internet information service platform can interrogate the remote client at any time for its bio-information. In addition, the system platform can compare data files. Bio-information and diabetes information can trigger timely alert messages. The system described in this paper could be the basis for a ubiquitous mobile physiological monitor.     

Sprinkler: A Reliable and Energy Efficient Data Dissemination Service for Extreme Scale Wireless Networks of Embedded Devices

We present Sprinkler, a reliable data dissemination service for wireless embedded devices which are constrained in energy, processing speed, and memory. Sprinkler embeds a virtual grid over the network whereby it can locally compute a connected dominating set of the devices to avoid redundant transmissions and a transmission schedule to avoid collisions. Sprinkler transmits O(1) times the optimum number of packets in O(1) of the optimum latency; its time complexity is O(1). Sprinkler is tolerant to fail-stop and state corruption faults. Thus, Sprinkler is suitable for resource-constrained wireless embedded devices. We evaluate the performance of Sprinkler in terms of the number of packet transmissions and the latency, both in an outdoor and indoor environment. The outdoor evaluation is based on data from project ExScal, which deployed 203 extreme scale stargazer (XSS). Our indoor evaluation is based on an implementation in the Kansei testbed, which houses 210 XSSs whose transmission power is controllable to even low ranges. We compare Sprinkler with the existing reliable data dissemination services, analytically or using simulations also. Our evaluations show that Sprinkler is not only energy efficient as compared to existing schemes, but also has less latency. Further, the energy consumption of nodes and the latency grows linearly as a function of newly added nodes as the network grows larger.     

From rate-distortion analysis to resource-distortion analysis

The ultimate goal in communication system design is to control and optimize the system performance under resource constraints. As the communication paradigm evolves from the conventional desktop computing, wired, and centralized communication to current mobile, wireless, distributed, and massive communication, video encoding and transmission operate under more and more resource constraints. In traditional video communication applications, such as digital TV broadcast, the major constraint is in the form of transmission bandwidth or storage space, which determines the encoding bit rate. Rate-distortion (R-D) theories have been developed to model the relationship between the coding bit rate and signal distortion. For video communication over mobile devices, the video encoding and transmission operate under additional resource constraints, such as energy supply and on-board computation capability. Therefore, there is a need to extend the traditional R-D analysis to resource-distortion analysis by incorporating the new resource constraints into the R-D analysis framework. In distributed and massive wireless video sensor networks, the resource utilization behaviors of individual video sensors should be well-coordinated through network-level rate allocation and optimum routing so as to maximize the overall performance. In this paper, we start from the classical R-D theory developed by Shannon over 50 years ago, and then review the R-D modelling techniques for modern image and video compression systems. We study the resource-distortion analysis framework for video communication over wireless devices. As one step further, we present the research problem of resource allocation and performance optimization for video compression and communication over a network of wireless communication devices.     

A Novel Multimedia Streaming Scheme for N-Screen Services in Wireless USB Networks

Ultra wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and a personal server in future telemedicine systems. Wireless universal serial bus (USB) is the USB technology merged with UWB technology. Wireless USB can be applied to wireless personal area network applications as well as personal area network applications like wired USB. In case of n-screen service applications, data traffics must broadcast to the adjacent devices However, the current wireless USB is designed to support the communication through the point-to-point connection between the host and the device only. This policy increases delay and energy consumption of wireless host and devices significantly. Therefore, in this paper, we propose a novel multimedia streaming scheme for n-screen service in wireless USB networks. The simulation results show that proposed protocol can enhance the throughput and delay performance and improve energy efficiency by minimizing the multimedia data delivery process.     

Energy‐efficient network selection with mobility pattern awareness in an integrated WiMAX and WiFi network

To provide wireless Internet access, WiFi networks have been deployed in many regions such as buildings and campuses. However, WiFi networks are still insufficient to support ubiquitous wireless service due to their narrow coverage. One possibility to resolve this deficiency is to integrate WiFi networks with the wide‐range WiMAX networks. Under such an integrated WiMAX and WiFi network, how to conduct energy‐efficient handovers is a critical issue. In this paper, we propose a handover scheme with geographic mobility awareness (HGMA), which considers the historical handover patterns of mobile devices. HGMA can conserve the energy of handovering devices from three aspects. First, it prevents mobile devices from triggering unnecessary handovers according to their received signal strength and moving speeds. Second, it contains a handover candidate selection method for mobile devices to intelligently select a subset of WiFi access points or WiMAX relay stations to be scanned. Therefore, mobile devices can reduce their network scanning and thus save their energy. Third, HGMA prefers mobile devices staying in their original WiMAX or WiFi networks. This can prevent mobile devices from consuming too much energy on interface switching. In addition, HGMA prefers the low‐tier WiFi network over the WiMAX network and guarantees the bandwidth requirements of handovering devices. Simulation results show that HGMA can save about 59– 80% of energy consumption of a handover operation, make mobile devices to associate with WiFi networks with 16–62% more probabilities, and increase about 20–61% of QoS satisfaction ratio to handovering devices. Copyright © 2009 John Wiley & Sons, Ltd.     

Design and implementation of a wireless internet remote access platform

Recently, mobile networks and internet technologies have been widely developed for the voice communication and information retrieval services all over the world. Compared with the wire‐line internet environment, mobile networks have lower bandwidth, longer transmission latency and unreliable connection, and the capability of mobile terminals is restricted by the limited memory size, lower CPU computation capability and inconvenient I/O interface. These limitations restrict the development of the wireless internet applications. In this paper, we design and implement a ‘wireless internet remote access platform’ (WIRAP). The WIRAP platform interconnects the wireless network and internet to provide mobile users a remote centralized storage and computation environment. A mobile user can store large volume of data and execute complex computations on WIRAP instead of on the mobile terminals. WIRAP supports different network interfaces (e.g. short message service (SMS), wireless markup language (WML) and hyper text markup language (HTML) and users may use terminals (with different network capabilities) to access WIRAP. Copyright © 2006 John Wiley & Sons, Ltd.     

Hierarchical Architecture for Multi-Technology Wireless Sensor Networks for Critical Infrastructure Protection

A hierarchical architecture for wireless sensor network (WSN) consisting of heterogeneous devices is introduced in this paper. Proposed architecture is well suited for surveillance of critical infrastructures and it is designed to be scalable for various different scenarios. Low power consumption will be achieved by utilizing a wake-up radio concept which enables to keep the most power consuming devices at the sleep mode as long as possible. A WSN OpenAPI gateway (WOAG) component of the architecture supports high scalability by enabling data collection and sharing from networks deployed using multiple different technologies. WOAG facilitates WSNs information availability to local and remote end-users. Analytical energy efficiency optimization model for the architecture is developed. Results show energy efficiency gains that can be achieved with the proposed wake-up concept based intelligent hierarchical architecture design. For low event frequency case the energy efficiency is found to be one order of magnitude better than for duty cycle (1 %) radio based network.     

Digital twin-based framework for wireless multimodal interactions over long distance

Wireless multimodal interactions over long distance (WMILD) would give rise to numerous thrilling applications, such as remote touching and immersive teleoperations. However, long distances can induce large propagation delays, which makes it difficult to meet the ultra-low latency requirements in haptic-visual interactions. Considering existing works mainly focused on the wireless access part, this paper designs an end-to-end framework for general WMILD applications based on the digital twin (DT) technology and proposes an intelligent resource allocation and parameter compression scheme to guarantee WMILD performance under constraint network resources. In the framework, user device can acquire real-time remote interactions by performing local interactions with nearby base station (BS), where a DT of the remote side is deployed to predict the remote haptic-visual feedbacks. A reliable DT updating process is carefully designed to guarantee the DT accurately model its dynamic physical counterpart. To optimize the updating reliability, we formulate the resource allocation and parameter compression to be a constraint-Markov decision problem, under the constraints on energy consumption, multimodal interactions and updating latencies. Then, a safe deep reinforcement learning algorithm is proposed to adapt resources and compression according to the dynamic DT updating workload, multimodal data-streams and remote transmission capacities. Simulation shows the framework can achieve high updating reliability compared with baselines.     

SparkMed: a framework for dynamic integration of multimedia medical data into distributed m-Health systems

With the advent of 4G and other long-term evolution (LTE) wireless networks, the traditional boundaries of patient record propagation are diminishing as networking technologies extend the reach of hospital infrastructure and provide on-demand mobile access to medical multimedia data. However, due to legacy and proprietary software, storage and decommissioning costs, and the price of centralization and redevelopment, it remains complex, expensive, and often unfeasible for hospitals to deploy their infrastructure for online and mobile use. This paper proposes the SparkMed data integration framework for mobile healthcare (m-Health), which significantly benefits from the enhanced network capabilities of LTE wireless technologies, by enabling a wide range of heterogeneous medical software and database systems (such as the picture archiving and communication systems, hospital information system, and reporting systems) to be dynamically integrated into a cloud-like peer-to-peer multimedia data store. Our framework allows medical data applications to share data with mobile hosts over a wireless network (such as WiFi and 3G), by binding to existing software systems and deploying them as m-Health applications. SparkMed integrates techniques from multimedia streaming, rich Internet applications (RIA), and remote procedure call (RPC) frameworks to construct a Self-managing, Pervasive Automated netwoRK for Medical Enterprise Data (SparkMed). Further, it is resilient to failure, and able to use mobile and handheld devices to maintain its network, even in the absence of dedicated server devices. We have developed a prototype of the SparkMed framework for evaluation on a radiological workflow simulation, which uses SparkMed to deploy a radiological image viewer as an m-Health application for telemedical use by radiologists and stakeholders. We have evaluated our prototype using ten devices over WiFi and 3G, verifying that our framework meets its two main objectives: 1) interactive delivery of medical multimedia data to mobile devices; and 2) attaching to non-networked medical software processes without significantly impacting their performance. Consistent response times of under 500 ms and graphical frame rates of over 5 frames per second were observed under intended usage conditions. Further, overhead measurements displayed linear scalability and low resource requirements.     

一种支持MD无线接入的新型混合式P2P模型

混合式P2P软件是目前互联网上广泛应用的P2P文件共享软件，但混合式P2P协议并没有特别考虑移动设备（Mobile Device）线接入的问题。文章将在混合式P2P模型的基础上，针对MD计算能力、存储能力的限制和无线连接的特点．提出一种支持MD无线接入的新型混合式P2P网络模型。它通过扩展移动支持节点的功能，使用移动代理代表MD接入P2P网络共享资源。并利用客户机缓存技术进行优化，有效的减少了MD自身的开销以及无线通信的开销．同时对MD的移动性和无线连接的断接性提供了很好的支持。     

地县广播电视台向无线数字发射站传送节目的技术方案

随着广播电视地面无线数字发射站建设的加快推行,本地广播电视台的数字节目需向发射站远程传送,目前主要依靠光缆传输和数字微波手段实现,在实施的过程中,需要综合考虑当地的网络状况、传输距离、设备选型、价格指标等多种因素,制定适合本地的传输规划方案,以保证电视节目的可靠传输。     

A System Design Approach for Unattended Solar Energy Harvesting Supply

Remote devices, such as sensors and communications devices, require continuously available power. In many applications, conventional approaches are too expensive, too large, or unreliable. For short-term needs, primary batteries may be used. However, they do not scale up well for long-term installations. Instead, energy harvesting methods must be used. Here, a system design approach is introduced that results in a highly reliable, highly available energy harvesting device for remote applications. First, a simulation method that uses climate data and target availability produces Pareto curves for energy storage and generation. This step determines the energy storage requirement in watt-hours and the energy generation requirement in watts. Cost, size, reliability, and longevity requirements are considered to choose particular storage and generation technologies, and then to specify particular components. The overall energy processing system is designed for modularity, fault tolerance, and energy flow control capability. Maximum power point tracking is used to optimize solar panel performance. The result is a highly reliable, highly available power source. Several prototypes have been constructed and tested. Experimental results are shown for one device that uses multicrystalline silicon solar cells and lithium-iron-phosphate batteries to achieve 100% availability. Future designers can use the same approach to design systems for a wide range of power requirements and installation locations.     

存储网络扩展研究

采用光传输和FCIP网络存储扩展技术，当灾难发生时保护当地存储网络中的数据的安全。使得本地的存储网络能够扩展至另一城市或国家的远地站点，从而同一份数据可以同步或异步的同时存储在本地和远程。当一地发生灾难时数据在另一地继续存在，从而保护了数据的安全。     

On Joint MAC and Network Coding in Wireless Ad Hoc Networks

This paper addresses network coding in wireless networks in conjunction with medium access control (MAC). It is known that coding over wired networks enables connections with rates that cannot be achieved by routing. However, the properties of wireless networks (e.g., omnidirectional transmissions, destructive interference, single transceiver per node, finite energy) modify the formulation of time-varying network coding in a way that reflects strong interactions with underlying MAC protocols and deviates from the classical approach used in wired network coding. To perform network coding over conflict-free transmission schedules, predetermined network realizations are separately activated by a time-division mechanism and the content of network flows is derived through network coding to optimize performance measures such as achievable throughput and energy costs. A systematic method is presented to construct linear wireless network codes and interactions with MAC schedules are discussed under wireless assumptions. Network coding is also extended to operate with arbitrary (random or scheduled access based) MAC protocols. Alternatively, conflict-free transmission schedules are jointly constructed with network codes by decomposing wireless networks into subtrees and employing graph coloring on simplified subtree graphs. Finally, network coding and plain routing are compared in terms of throughput, energy and delay performance under different MAC solutions.     

Void traversal for efficient non-planar geometric routing

Geometric routing provides a scalable and efficient way to route messages in ad hoc networks if extensive routing information is unavailable. Such algorithms require a planar graph to guarantee message delivery. The routing techniques for such guarantee usually center around the traversal of planar faces of the graph. However, in realistic wireless networks existing planarization methods, if at all applicable, tend to require extensive local storage or result in suboptimal route selection. In this paper we study an alternative approach of translating the algorithms themselves to be able to route messages over voids in non-planar graphs. We prove sufficient memory requirements for such translations. We then translate several well-known planar geometric routing algorithms and evaluate their performance in both static and mobile networks.     

基于无线传感网络的手机实时医疗监护系统简

针对通过住院观察病人的心电图来对心血管疾病进行诊断的方法的不足,文中采用无线传感网络作为监控系统的信息采集平台,将其应用于人体健康监控领域,设计并实现了一款基于无线传感网络的手机实时医疗监护系统。系统通过无线传感网络来对患者的心电数据进行集中式管理．并可通过医生工作站来实现对患者的远程病情诊断。与目前现有的远程医疗监护系统相比,基于无线佳感网络的手机实时医疗监护系统具有精确度高、实时性好、能耗低、部署方便、设备廉价等一系列优势。     

Resource Allocation for Aggregate Multimedia and Healthcare Services over Heterogeneous Multi-Hop Wireless Networks

Nowadays, the pervasive wireless networks enable ubiquitous high-rate wireless access from everywhere. In this work, we discuss the integration of complementary wireless techniques to construct a personal moving network. The personal wireless devices (  smartphones, camcorders, and netbooks) and even medical monitoring sensors are interconnected with a wide-area backbone through a local multi-mode gateway. The mobile nodes in a personal moving network move in group and are provided seamless connectivity through a backhaul relay channel from the local gateway toward the backbone network. In some specific scenarios, the local gateway can be as simple as a multi-radio smartphone. In this study, we investigate the construction and resource allocation for a personal moving network. Aggregate multi-service traffic of interactive data, conversational video, and electrocardiography (ECG) monitoring are considered in the resource allocation. We develop a stochastic Petri net to model the access selection scheme, which is logically clear and easy to follow. The flow-level performance is evaluated in terms of new connection blocking probability and handoff dropping probability. We further analyze the packet-level performance of the heterogeneous two-hop network. Considering the urgency of medical services, a non-preemptive priority policy is applied to mitigate the impact of background traffic and prioritize the transmission of ECG data.