Search results for "internet"
showing 10 items of 2589 documents
Security Enhancement of Peer-to-Peer Session Initiation
2012
Today, Peer-to-Peer SIP based communication systems have attracted much attention from both the academia and industry. The decentralized nature of P2P might provide the distributed peer-to-peer communication system without help of the traditional SIP server. However, the decentralization features come to the cost of the reduced manageability and create new concerns. Until now, the main focus of research was on the availability of the network and systems, while few attempts are put on protecting privacy. In this chapter, we investigate on P2PSIP security issues and introduce two enhancement solutions: central based security and distributed trust security, both of which have their own advanta…
Low-cost active cyber defence
2014
The authors of this paper investigated relatively simple active strategies against selected popular cyber threat vectors. When cyber attacks are analysed for their severity and occurrence, many incidents are usually classifi ed as minor, e.g. spam or phishing. We are interested in the various types of low-end cyber incidents (as opposed to high-end state- sponsored incidents and advanced persistent threats) for two reasons: • being the least complicated incidents, we expect to fi nd simple active response The authors analysed the proposed strategies from the security economics point of view to determine why and how these strategies might be effective. We also discuss the legal aspects of th…
Reliable Underlay Device-to-Device Communications on Multiple Channels
2019
Device-to-device (D2D) communications provide a substantial increase in spectrum usage and efficiency by allowing nearby users to communicate directly without passing their packets through the base station (BS). In previous works, proper channel assignment and power allocation algorithms for sharing of channels between cellular users and D2D pairs, usually require exact knowledge of the channel-state-information (CSI). However, due to the non-stationary wireless environment and the need to limit the communication and computation overheads, obtaining perfect CSI in the D2D communication scenario is generally not possible. In this work, we propose a joint channel assignment and power allocati…
Uplink DPCCH Gating of Inactive UEs in Continuous Packet Connectivity Mode for HSUPA
2007
In order to further improve the packet performance in the UMTS FDD system, uplink dedicated physical control channel (DPCCH) gating as a scheme is proposed in 3GPP under the work item "continuous connectivity for packet data users". In this paper, the uplink DPCCH gating concept is described and analyzed on both a qualitative and a quantitative level. And the system performance of different gating patterns used in the scheme was investigated by analytical prediction and system level simulations with different channel profiles. As shown, the selection of the gating pattern has a significant influence on the system performance, which is correlated with the uplink data transmission activity an…
Cooperative or non-cooperative transmission in synchronous DC WSNs: A DTMC-based approach
2017
Cooperative transmission (CT) enables balanced energy consumption among sensor nodes and mitigates the energy hole problem in wireless sensor networks (WSNs). In typical CT enabled medium access control (MAC) protocols, a source node decides to trigger CT or not based on a residual energy comparison between itself and its relay node. In this paper, we propose a receiver initiated CT MAC protocol, in which the receiving node makes the decision on initiating CT or not based on a tradeoff between performing CT and non-CT. In this way, nodes can avoid idle listening and achieve an extended lifetime. A discrete-time Markov chain (DTMC) model is developed to analyze the performance of CT associat…
Energy-Efficient Binary Power Control with Bit Error Rate Constraint in MIMO-OFDM Wireless Communication Systems
2012
Motivated by the demand for energy efficiency improvement in mobile communication industry, we explore an idea of optimizing energy efficiency for MIMO-OFDM wireless communication systems while maintaining users' quality of service (QoS) requirement. Based on the binary power control scheme,a power allocation criterion for energy efficiency optimization is derived under the total power constraint. From a bit error rate (BER) point of view, a protection constraint is configured to guarantee the system QoS. With the aim of energy efficiency optimization under QoS guarantee in MIMO-OFDM wireless communication systems, an energy-efficient binary power control with BER constraint (EBPCB) algorith…
Adoption of Constrained Application Protocol
2016
Among billions of Internet enabled devices that are expected to surround us in the near future, many will be resource constrained, i.e., will have limited power supply, processing power and memory. To cope with these limitations, the Constrained Application Protocol (CoAP) has been recently introduced as a lightweight alternative to HTTP for connecting the resource limited devices to the Web. Although the new protocol offers solid technical advantages, it remains uncertain whether a successful uptake will follow, as it depends also on its economic feasibility for the involved stakeholders. Therefore, this paper studies the techno-economic feasibility of CoAP using a systematic methodologica…
Research opportunities in performance measurement in public utilities regulation
2015
Purpose – The purpose of this paper is to propose a method to choose a set of scientific articles about performance measurement in public utilities regulation. The method is designed to identify references with high academic relevance in databases accessed via the internet, and, through these articles, to perform a mapping of these publications and conduct a systemic analysis. Design/methodology/approach – The study is characterized as exploratory and descriptive with a qualitative and quantitative approach. Incorporates an inductive logic, and draws on primary and secondary data sources. The research involves the application of a technical procedure for selection and study of selected art…
A continuous-space analytical approach for relay node placement in hybrid cellular and ad hoc networks
2009
A hybrid network is composed of a cellular component and an ad hoc component connected by a relay node, for the purpose of coverage extension and/or capacity improvement. In this paper, we analyze the capacity of such a hybrid network by employing a continuous-space analytical methodology based on circular geometry for uniformly distributed nodes. To achieve maximal overall capacity, the relay node needs to be placed in an optimum location between the base station and the mobile station located at the boundary of the hybrid network. Numerical results show that for obtaining the optimum overall capacity for the hybrid network, the placement of the relay node should be in a range which is nei…
An Integrated Wireless Communication Architecture for Maritime Sector
2011
Published version of a chapter in the book: Multiple Access Communications. Also available from the publisher at http://dx.doi.org/10.1007/978-3-642-23795-9_17 The rapid evolution of terrestrial wireless systems has brought mobile users more and more desired communication services. Maritime customers are asking for the same, such as the concepts of “Broadband at Sea” and “Maritime Internet”. Quite a lot of research work has focused on the development of new and better maritime communication technologies, but less attention has been paid on interworking of multiple maritime wireless networks or on satisfying service provisioning. To address this, an integrated wireless Communication Architec…