(1991). Applied Linear Regression Models. Journal of Quality Technology: Vol. 23, No. 1, pp. 76-77.

Applied Linear Regression Models

Network function virtualization was recently proposed to improve the flexibility of network service provisioning and reduce the time to market of new services. By leveraging virtualization technologies and commercial off-the-shelf programmable hardware, such as general-purpose servers, storage, and switches, NFV decouples the software implementation of network functions from the underlying hardware. As an emerging technology, NFV brings several challenges to network operators, such as the guarantee of network performance for virtual appliances, their dynamic instantiation and migration, and their efficient placement. In this article, we provide a brief overview of NFV, explain its requirements and architectural framework, present several use cases, and discuss the challenges and future directions in this burgeoning research area.

Network function virtualization: Challenges and opportunities for innovations

The protection of data on a client mobile computing device by a server computer system such as within an enterprise network or on a separate mobile computing device is described. Security tools are described that provide different security policies to be enforced based on a location associated with a network environment in which a mobile device is operating. Methods for detecting the location of the mobile device are described. Additionally, the security tools may also provide for enforcing different policies based on security features. Examples of security features include the type of connection, wired or wireless, over which data is being transferred, the operation of anti-virus software, or the type of network adapter card. The different security policies provide enforcement mechanisms that may be tailored based upon the detected location and/or active security features associated with the mobile device. Examples of enforcement mechanisms are adaptive port blocking, file hiding and file encryption.

Administration of protection of data accessible by a mobile device

A super-peer is a node in a peer-to-peer network that operates both as a server to a set of clients, and as an equal in a network of super-peers. Super-peer networks strike a balance between the efficiency of centralized search, and the autonomy, load balancing and robustness to attacks provided by distributed search. Furthermore, they take advantage of the heterogeneity of capabilities (e.g., bandwidth, processing power) across peers, which recent studies have shown to be enormous. Hence, new and old P2P systems like KaZaA and Gnutella are adopting super-peers in their design. Despite their growing popularity, the behavior of super-peer networks is not well understood. For example, what are the potential drawbacks of super-peer networks? How can super-peers be made more reliable? How many clients should a super-peer take on to maximize efficiency? we examine super-peer networks in detail, gaming an understanding of their fundamental characteristics and performance tradeoffs. We also present practical guidelines and a general procedure for the design of an efficient super-peer network.

Designing an Super-Peer Network

With the success of wireless technologies in consumer electronics, standard wireless technologies are envisioned for the deployment in industrial environments as well. Industrial applications involving mobile subsystems or just the desire to save cabling make wireless technologies attractive. Nevertheless, these applications often have stringent requirements on reliability and timing. In wired environments, timing and reliability are well catered for by fieldbus systems (which are a mature technology designed to enable communication between digital controllers and the sensors and actuators interfacing to a physical process). When wireless links are included, reliability and timing requirements are significantly more difficult to meet, due to the adverse properties of the radio channels. In this paper, we thus discuss some key issues coming up in wireless fieldbus and wireless industrial communication systems: 1) fundamental problems like achieving timely and reliable transmission despite channel errors; 2) the usage of existing wireless technologies for this specific field of applications; and 3) the creation of hybrid systems in which wireless stations are incorporated into existing wired systems.

/pdf/wireless-technology-in-industrial-networks-3inkv4crnj.pdf

Wireless Technology in Industrial Networks

https://www.cs.umd.edu/projects/p2prg/p2p-overview.pdf

Survey of research towards robust peer-to-peer networks: search methods

The IEEE 802.11 MAC protocol supports two modes of operation, a random access mode for non-real-time data applications, and a polling mode for real-time applications. We design and analyze a system that uses the polling mode for interactive voice traffic. With larger inter-poll periods, more voice calls can be accommodated, but at the expense of increased delay. For example, our analysis shows that with an inter-poll period of 90 ms, a maximum of 26 voice calls can be handled with a worst-case delay of 303 ms, whereas with an inter-poll period of 60 ms, a maximum of 17 voice calls can be handled with a worst-case delay of 213 ms. We also carry out an error analysis that demonstrates the need for error correction of voice packets.

/pdf/support-of-voice-services-in-ieee-802-11-wireless-lans-1pbvyr4gvl.pdf

Support of voice services in IEEE 802.11 wireless LANs

This paper proposes an admission control algorithm that enables the upcoming IEEE 802.11e contention based enhanced distributed channel access (EDCA) to provide quantitative bandwidth guarantees for wireless local area networks (WLANs), rather than a relative prioritized service. The algorithm estimates the throughput that flows would achieve if a new flow with certain parameters was admitted, and so indicates whether such a new flow can be admitted while preserving the quality of service (QoS) of existing flows. The algorithm deals with the EDCA parameters of minimum contention window size and transmission opportunity duration, and indicates what values should be used for different flows. Simulation results confirm the accuracy of the throughput estimates and the effectiveness of the admission control algorithm.

Call admission control for IEEE 802.11 contention access mechanism

Transferring data (such as files) on an end-to-end, high-speed packet-switched network connection (a “virtual circuit”) or on a circuit. An out-of-band path is used for signaling and status messages (control). The same, or a separate, out-of-band path may be used to retransmit chunks of data that were received with errors or that were not received at all. By simplifying the data being sent over the high-speed (virtual) circuit, the resources of the (virtual) circuit are used efficiently since less overhead is required. Further, since the size of the file to be transferred can be predetermined, and since any retransmissions can be made over a path other than the (virtual) circuit, the (virtual) circuit that best meets the needs of the data transfer can be selected, thereby further increasing the efficiency with which the (virtual) circuit is used.

Transferring data such as files

This article first discusses how advances in networking architectures and protocols can complement advances in optical communications research to increase the overall value of optical networks by enabling more applications. A review of existing optical networking solutions is then provided along with a classification of different types of optical networks. Finally, we show how single-hop and multihop wavelength-routed networks can be used efficiently for fast end-to-end file transfers when these networks are equipped with a hardware-implementable signaling protocol, a routing protocol, and a simple transport protocol.

Tim Moors

Papers

Survey of research towards robust peer-to-peer networks: search methods

Support of voice services in IEEE 802.11 wireless LANs

Call admission control for IEEE 802.11 contention access mechanism

Transferring data such as files

Architectures and protocols that enable new applications on optical networks