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Distributed storage systems suffer from significant repair traffic generated due to frequent storage node failures. This paper shows that properly designed low-density parity-check (LDPC) codes can substantially reduce the amount of required block downloads for repair thanks to the sparse nature of their factor graph representation. In particular, with a careful construction of the factor graph, both...
Tactile internet requires ultra-low latency and ultrahigh reliability, which bring new challenges to the design of mobile systems. In this paper, we study how much resources are required to ensure the short end-to-end (E2E) delay and high reliability by taking a vehicle communication system as an example, where the E2E delay includes both queueing delay and transmission delay, and the reliability...
In this paper we present a novel configurable 5G time division duplex (TDD) frame structure, including a flexible scheduling (resource allocation) framework for wide area scenarios. The unavoidable tradeoffs between coverage, latency, and capacity are studied with the objective of deriving a 5G air interface solution that is capable of serving users with highly diverse service requirements. Among...
The paper presents an assessment of the reliability of medium voltage networks within a power company. Reliability of power supply in medium voltage networks is one of the commonly recognized targets of Smart Grid. Novel approaches are needed for evaluating the reliability of electricity distribution and the reliability of supply in distribution network planning. This paper presents a stochastic supply...
To ensure the reliability of distributed storage systems, we studied network bandwidth-aware multiple fault tolerant erasure codes. A flat XOR code is one of the sparse graph codes designed for distributed storage systems. It encodes and decodes data by exclusive OR (XOR) operation with low complexity. However, conventional construction methods of flat XOR codes are not optimal in terms of repair...
Three-dimensional DRAM stacking has emerged as a vehicle for scaling system densities and performance improvement. The two design choices for interfacing to processors are — i) a separate core die connected to the DRAM stack via a silicon interposer (2.5D), and ii) DRAM die stacked on top of the core die (3D). These alternatives have different performance, power, and reliability behaviors. Specifically,...
Software-defined networking (SDN) is well-known of its programmable and centralized management mechanism of networks. The controller unit in SDN enables users to determine network behaviors by defining flow rules on programmable switches in SDN. In this paper, we briefly propose a novel concept of network storage systems. Unlike most network storage systems store files on hosts and access files through...
As peer to peer systems work in open environment, they are highly susceptible to malicious activities. Formation of trust relations between the peers help to minimize the impact of such attacks. This paper proposes a collaborative trust based model that works on reputation and recommendations metrics to increase trustworthiness amongst the peers for reliable services. Under this model, evaluator contacts...
Wireless sensor networks (WSNs) are susceptible to most security attacks. There are some limitations such as reliability, energy efficiency, and scalability, which affect sensor nodes. These limitations mostly affect the security of wireless networks. Also, limited capacity of sensor nodes accounts for the security attacks on WSNs. Applications such as military surveillance, traffic surveillance,...
With the recent rise in cloud computing, applications are routinely accessing and interacting with data on remote resources. As data sizes become increasingly large, often combined with their locations being far from the applications, the well known impact of lower TCP throughput over large delay-bandwidth product paths becomes more significant to these applications. While myriads of solutions exist...
The Internet of Things (IoT) embeds sensors, actuators and computation into everyday 'things' such as lights and thermostats. These things form low-power wireless networks connecting to the Internet via IPv6 for monitoring and control. Such IoT systems are increasingly subject to runtime reconfiguration, wherein new hardware and software may be installed dynamically to accommodate changing application...
This paper highlights the benefits of IEEE 802.15.4's unslotted carrier sense multiple access collision avoidance (CSMA-CA) MAC layer acknowledgements (ACKs) in ad-hoc wireless networks. We performed different experimental studies to analyse the impact of enabling and disabling the ACKs on event detection ratio (EDR), available bandwidth estimator, and flow admission control algorithms. Comparison...
Media production networks connect different actors such as production houses, broadcasters and advertisers over a large geographical area. The substrate network in a media production process can be shared among many users simultaneously. These networks often have predictable traffic, meaning that the timing and bandwidth requirements of data transfers are generally known at least hours or even days...
This paper designs an underlay control channel for noncontiguous-OFDM-based cognitive networks. Noncontiguous OFDM (NC-OFDM) provides a fast and flexible manner of accessing disjoint parts of the spectrum and is ideally suited for dynamic spectrum access. While similar to OFDM, NC-OFDM explicitly restricts transmission to only certain subcarriers that are free of incumbent transmissions. In particular,...
While using Wireless Sensor Network for monitoring the remote patient's health situations, data related to that patient is stored in the sensors and the huge amount of data results in buffer and link overflow. The buffer and link overflow causes the problem of congestion which results in loss of packet and transmission delay. Congestion is a situation in which buffer overloaded with excessive data,...
This paper deals with design of planar Goubau line (PGB) antenna for partial discharge (PD) measurement. In the design, planar Goubau line antennas are simulated with a variety of shapes and sizes by using software HFSS to get the corresponding frequency response with the frequency of occurrence of PD. Planar goubau line antenna is designed with the type of substrate FR4_epoxy ranging from the size...
Through analyzing the storage system requirements of supercomputer this paper designs a near-line storage system called NLSS based on the combination of HDFS (Hadoop distributed file system) and ZFS (Zettabyte file system). NLSS uses fat storage nodes (large storage servers) to build near-line storage clusters based on HDFS, and uses the ZFS file system to further enhance HDFS. NLSS effectively reduces...
Even after decades, the Internet does not provide Quality of Service (QoS) guarantee for the users. In order to soften such situation, clients negotiate Service Level Agreements (SLAs) with their Internet Service Providers (ISPs), where reliability and available bandwidth are key requirements for Internet services. On the other hand, the ISPs aim to decrease the energy consumption to deliver their...
Factory automation is one of the challenging use cases that the fifth generation, 5G, networks are expected to support. It involves mission-critical machine-type communications, MTC, with requirements of extreme low-latency and ultra-reliable communication to enable real-time control of automation processes in manufacturing facilities. In this paper, we discuss the deployment strategies for the 5G...
After several years of research towards sophisticated QoS measurement tools and methods, the results given to endusers by most commonly used on-line speed measurement tools are still far from being precise. In order to define a reliable Internet speed measurement methodology for endusers, the impact that the static and dynamic constraints of network nodes and TCP/IP implementations could impose must...
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