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Mobile peer-to-peer (P2P) traffic is rapidly growing, but present P2P applications are not specifically designed to operate under mobile conditions. To assess the performance of the prevalent file sharing application BitTorrent in a mobile WiMAX network, we performed a measurement and analysis campaign. In this study, we use the obtained measurement traces to further investigate specific characteristics...
When using the web, long response times are bones of contention for users, i.e. they damp the Quality of Experience (QoE). Though, if one knows the cause of the long response time one may examine what could be done to eliminate the obstacle. In this paper, we determine the weak point of the Extensible Authentication Protocol Method for GSM Subscriber Identity Modules (EAP-SIM) with the OpenID service...
Ongoing research in Optical Burst Switching (OBS) requires more in-depth studies both in theory and in practice before the technology is realized. In OBS paradigm, traffic from access networks is groomed at edge OBS nodes in the forms of large chunks called bursts. This grooming called assembly is crucial in analyzing the overall performance of OBS networks as it affects the esign of almost all major...
Due to the variation of radio condition in LTE the obtainable bitrate for active users will vary. The two most important factors for the radio conditions are fading and pathloss. By considering analytical analysis of the LTE conditions including both fast fading and shadowing and attenuation due to distance we have developed a model to investigate obtainable bitrates for customers randomly located...
In this paper, a multipath routing scheme is proposed for data transmission in a packet-switched network to improve the reliability of data delivery to multicast destinations, and to reduce network congestion. A multi-objective optimization model is presented that utilizes FEC (Forward Error Correction) across multiple multicast trees for transmitting packets toward the destinations. This model assigns...
In this paper, we propose analytical model of Virtual Link used in the Service Overlay Networks. The Virtual Link exploits Selective Repeat ARQ scheme with time constrained number of retransmission and the playout buffer mechanism. Our model allows deriving equations that express trade-off between loss and delay characteristics experienced by packets transferred through VL. The main innovation of...
In this paper we present a new algorithm for evaluating queueing networks with multi-rate traffic. The detailed state space of a node is evaluated by explicit formulæ. We consider reversible nodes with multi-rate traffic and find the state probabilities by taking advantage of local balance. Theory of queueing networks in general, presumes that we have product form between the nodes. Otherwise, we...
We consider a single-link loss system of fixed capacity, which accommodates K service-classes of Poisson traffic with elastic bandwidth-per-call requirements. When a new call cannot be accepted in the system with its peak-bandwidth requirement, it can retry one or more times (single and multi-retry loss model, respectively) to be connected in the system with reduced bandwidth requirement and increased...
In this paper we investigate multi-service load balancing mechanisms in an overlay heterogeneous WiMAX/WLAN network through vertical handover. Considering the service characteristics of the overlay heterogeneous network together with the service requirements of different applications, all streaming applications are served in WiMAX while elastic applications are distributed to WiMAX and WLAN. Two load...
This paper discusses compact node-link formulations for MPLS fast reroute optimal single path layout. We propose mathematical formulations for MPLS fast reroute local protection echanisms. In fact, we compare one-to-one (also called detour) local protection and many-to-one (also called facility backup) local protection mechanisms with respect to minimized maximum link utilization. The optimal results...
In this paper we introduce our new VoIP model the aim of which is to meet the challenges of modern telephony. We present project concepts, details of implementation and our testing environment which was designed for testing many aspects of VoIP based systems. Our system combines mechanisms for ensuring best possible connection quality (QoS), load balance of servers in infrastructure, providing security...
The aim of this paper is to introduce a problem of e-health services quality management. The process of delivering e-health services to users consists of two major tasks: service ersonalization and resources allocation. In this paper we introduce a use-cases of e-health system and distinguish services that can be offered. In order to satisfy user requirements one has to manage esources properly especially...
This paper proposes a novel source detection technique and details the requirements of the measurement system and the necessary data processing. The procedure employs standard antenna pattern measurement methods to extract directional information of the surrounding propagation channel. Acalculated magnitude ratio ultimately allows a three dimensional spatial map of the surrounding radiation sources...
We consider a bounded square-shaped ad hoc network scenario, within which packet arrivals are distributed randomly in space and time according to a 3-dimensional Poisson Point Process. Each packet is transmitted over a single hop to its destination, located a fixed distance away. Within this context, the outage probability of the ALOHA and CSMA protocols is derived, and we evaluate the impact of edge...
Cooperative hybrid ARQ (HARQ) protocols have been widely studied in recent years and they were shown to provide higher efficiency than cooperative protocols. This paper proposes a joint design within which the HARQ protocol collaborates with the link adaptation functionality and the cooperative transmission scheme in order to adapt the behavior of the HARQ protocol to the QoS requirements of the supported...
Prediction of future idle times of different channels based on history information allows a cognitive radio (CR) to select the best channels for control and data transmission. In contrast to earlier work, the proposed method works not only with a specific type of traffic but learns and classifies the traffic type of each channel over time and can select the prediction method based on that. Different...
In this paper we present an approach for supporting best effort traffic on an ECOFRAME ring network which has been dimensioned primarily for Guaranteed Traffic. This approach is reservation based, and is combined within the ECOFRAME MAC with the opportunistic access method used for Guaranteed traffic. The reservation method is intended to both protect the Guaranteed traffic and allocate fair shares...
In wireless body area networks, on-body radio propagation channels are typically time-varying, because of the frequent body movements. The dynamic local body scattering dominates the temporal and spatial properties of the on-body channels. The influence varies largely depending on the distribution of the channels and the modes of body movements. In this paper, we present some major achievements on...
This paper discusses the performance of antenna selection technique in space time turbo coded MIMO-OFDM systems. Multiple-input multiple-output (MIMO) technology can either increase the data rate through spatial multiplexing or improve the reliability through diversity. Space-time turbo codes (STTC) have been proposed to provide robust communications in MIMO wireless environment. STTC technique incorporates...
In this paper the application of the concept of crystallized rate regions to MIMO transmission with femtocell interference is investigated. Based on the referenced work a new game definition specifying the new cost function derived for MIMO transmission with femtocell interference is proposed. Furthermore, the idea of channel approximation for complexity reduction is described. Finally, the simulation...
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