| 1. |
- Fodor, Viktoria, et al.
(författare)
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On the gains of deterministic placement and coordinated activation in sensor networks
- 2008
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Ingår i: GLOBECOM 2008 - 2008 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE. - 9781424423248 ; , s. 335-340
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Konferensbidrag (refereegranskat)abstract
- In this paper we discuss topology design and dimensioning of sensor networks to achieve full sensing coverage. We consider two ways of deploying the sensors, placing them according to some regular pattern or scattering them randomly, and two ways of activating the sensors, optimally according to some predefined schedule or randomly, when each sensor follows a wake-up schedule independently from the other sensors. We provide analytic expressions for the necessary and sufficient number of sensors that guarantee coverage in these scenarios and determine the cases when deterministic sensor placement or optimal sensor activation can achieve significant gains. We consider sensing with bounded delay and show that the number of sensors to be deployed can be decreased significantly even at low sensing delays.
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| 2. |
- Salvo Rossi, Pierluigi, et al.
(författare)
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Performance of an Iterative Multi-User Receiver for MIMO-OFDM Systems in a Real Indoor Scenario
- 2008
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Ingår i: [Host publication title missing]. - 1930-529X. - 9781424423248
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Konferensbidrag (refereegranskat)abstract
- This paper aims at validation of an iterative receiver for multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) systems using real-measurement channel data from an indoor scenario. The receiver performs iterative multi-user detection (MUD) and Channel Estimation (CE) via soft information from the single- user decoders. The channel measurements were performed for a dynamic dual MIMO link scenario. The case with two users with multiple antennas interfering each other is considered. CE at the receiver exploits the frequency correlation of the MIMO link. Simulation results for the performance are shown in terms of bit- error rate (BER) vs. signal-to-noise ratio (SNR). Performance for the whole system are provided and compared with respect to the case of perfect channel-state information (PCSI) at the receiver, as well as for the single user. We also provide an analysis of BER with respect to signal-to-interference ratio (SIR). CE performance are evaluated in terms of normalized mean square error (NMSE).
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| 3. |
- Schmidt, Mischa, et al.
(författare)
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Voice Call Continuity : A Critical Step Towards All-IP Based Next Generation Networks
- 2008
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Ingår i: IEEE GLOBECOM 2008, Global Telecommunications Conference. - Piscataway, NJ : IEEE Communications Society. - 9781424423248 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- The recent developments in the fixed and mobile telecommunication industry, namely the rapid penetration of broadband access and new charging models in the broadband market in conjunction with the success of wireless local area networks and the general trend of fixed and mobile convergence, are transforming the telecommunication landscape. One of the main challenges is to integrate the fixed and mobile technologies in a way that leverages the strengths of different technologies and improves the service experience for the end user. A crucial step for this transformation is to provide adequate support for users to seamlessly switch between network domains and technologies. The main contribution of this paper is a solution that allows a mobile terminal to change from the mobile radio access to the fixed/cable access provided over a local wireless network or vice versa without disrupting an active ongoing voice call. The implementation of the proposed solution was tested and evaluated in an experimental network with real voice calls.
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| 4. |
- Soldati, Pablo, et al.
(författare)
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A low-signalling scheme for distributed resource allocation in multi-cellular OFDMA systems
- 2008
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Ingår i: GLOBECOM 2008 - 2008 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE. - 9781424423248 ; , s. 3718-3723
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Konferensbidrag (refereegranskat)abstract
- This paper considers distributed protocol design for joint sub-carrier, transmission scheduling and power management in uplink/downlink multi-cellular OFDMA wireless networks. The optimal solution to this problem is hard to achieve, both in theory and in practice. We propose a fully decentralized resource allocation scheme combining decomposition methods for convex optimization with a strategic non-cooperative game formulation of the power and sub-carrier allocation subproblem. Although the final protocols are suboptimal, they drastically reduce computation time while maintaining the overall system performance close to the optimal, exhibiting strong robustness to multiple access interference. We validate the theoretical framework and quantify the performance with numerical examples.
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| 5. |
- von Wrycza, Peter, 1981-, et al.
(författare)
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Game Theoretic Approach to Spectrum Allocation for Weak Interference Systems
- 2008
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Ingår i: GLOBECOM 2008 - 2008 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE. - 9781424423248 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- A scenario consisting of two transmitter-receiver pairs coexisting in the same area and communicating using the same portion of the spectrum is considered. Decentralized coding strategies are employed at the transmitter side and no cooperation is assumed between the two systems. We investigate the structure of Nash equilibria corresponding to simultaneous water-filling solutions and propose a scheme that improves overall performance of systems with weak mutual interference. The resulting scheme provides a spectrum sharing rule in the form of a modified utility function. The conditions for optimality are presented and a numerical example illustrates the performance compared to a scheme employing the link rate as utility function.
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| 6. |
- Winkler, F., et al.
(författare)
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Enriching IPTV Services and Infrastructure with Identity Management
- 2008
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Ingår i: IEEE GLOBECOM 2008, Global Telecommunications Conference. - Piscataway, NJ : IEEE Communications Society. - 9781424423248
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Bokkapitel (refereegranskat)abstract
- IPTV is regarded as one of the key technologies of triple play services by telecommunication incumbents. It is seen as the differentiator to reduce customer churn. However, as more operators deploy this service, the factors for differentiation are dissolving rapidly. In this paper we present how identity management can enrich IPTV and thus provide a variety of new business opportunities that will foster an operator's position and the contractual bindings with its customers. We present novel business models that are made possible by integrated identity management and describe their importance to the user. Furthermore, we address privacy aspects for IPTV service portfolios - a topic which is crucial to gain user acceptance for new services.
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| 7. |
- Winkler, Florian, et al.
(författare)
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Identity management for IMS-based IPTV
- 2008
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Ingår i: 2008 IEEE Global Telecommunications Conference. - Piscataway, NJ : IEEE Communications Society. - 9781424423248 ; , s. 1637-1641
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Konferensbidrag (refereegranskat)abstract
- IPTV as an integral part of triple play service offers is regarded as a major differentiation factor by incumbent telecommunication operators. However, as more operators provide these services, differentiation is fading. Analysts agree that the key to differentiation are value added services which in the long term require business collaborations of incumbents and 3rd party Service Providers. Additional value is added by integrating existing and well known Internet services into those service portfolios.In this paper, we present how Identity Management technology can simplify the setup of these collaborations and enhance the user experience by secure, anonymous and seamless service usage, e.g. by providing Single Sign On and pseudonyms. We furthermore detail an architecture that combines IPTV based on the IPMultimedia Subsystem with Identity Management to offer consumers a comfortable, privacy aware access to value added services. Especially in the context of IPTV, these are important attributes to reach a high and sustainable user acceptance.
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