| 1. |
- Hammarberg, Peter, et al.
(författare)
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On the performance of iterative receivers for interfering MIMO-OFDM systems in measured channels
- 2008
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Ingår i: 42nd Asilomar Conference on Signals, Systems and Computers. - 1058-6393. - 9781424429400 ; , s. 141-145
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the gains harvested through base station cooperation in the up-link for a multi-user (MU) Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system, operating in a real indoor environment. The base stations perform joint detection using an iterative receiver that carries out multi-user detection and channel estimation via soft information from the single-user decoders. Performance evaluation is carried out using real channels from an indoor dynamic dual MIMO link measurement campaign. The measured scenario represent a real life situation where two users communicate with two base stations, each with two antennas, in an environment resembling a shopping mall or an airport terminal. System performance is evaluated in terms of both Bit-Error Rate (BER) vs. Signal-to-Interference Ratio (SIR) and Cumulative Distribution Functions (CDF) for the instantaneous BER. Also, the impact of using soft information in the channel estimation is analyzed.
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| 2. |
- Lioliou, Panagiota, 1982, et al.
(författare)
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Performance Analysis of Relay Channel Estimation
- 2009
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Ingår i: 43rd Asilomar Conference on Signals, Systems and Computers; Pacific Grove, CA; United States; 1 November 2009 through 4 November 2009. - 1058-6393. - 9781424458271 ; , s. 1533-1537
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Konferensbidrag (refereegranskat)abstract
- Amplify-and-Forward (AF) relays can be used to enhance the channel in Multiple-Input-Multiple-Output (MIMO) wireless communication systems. However, optimizing the channel requires Channel State Information (CSI). This paper is concerned with the performance of relay channel estimation. A Least Squares (LS) based algorithm for the estimation of all relevant channel parameters was recently proposed by the authors. It is based on creating different compound channels by varying the gain factors at the relays. From this, the individual links from source to relay and from relay to destination, are revealed using LS. To investigate the algorithm performance, the Cramér-Rao lower Bound (CRB) is computed and compared with the asymptotic covariance of the proposed estimator. Furthermore, we propose and analyze an improved algorithm that is efficient for high Signal-to-Noise Ratio (SNR). Computer simulations demonstrate the performance of the algorithm. The results indicate that the asymptotic expressions are in good agreement with the simulations.
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| 3. |
- Solano, F., et al.
(författare)
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Online impairments-aware routing within a path computation element
- 2009
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Ingår i: [Host publication title missing]. - 1058-6393. - 9781424458257 ; , s. 1048-1052
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Konferensbidrag (refereegranskat)abstract
- A Path Computation Element (PCE) is a computing device in a network capable of calculating paths. Once a PCE receives a path computation request, the PCE is suppose to provide a response within a reasonable short time. However, computing a feasible path is not a straightforward task, since the computational problem must consider several constraints in a short time. In this paper we propose an algorithm for light-paths computation for this purpose that is intended to comply with the PCE standard. Our algorithm considers optical impairments, wavelength conversion and nodes with limited switching capabilities. Optical impairments are estimated using a Q-factor. The routing problem is solved using Multi-Constrained Shortest Path exact algorithm.
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| 4. |
- Tomaszewski, A., et al.
(författare)
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Minimization of label usage in (G) MPLS network
- 2009
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Ingår i: [Host publication title missing]. - 1058-6393. - 9781424458257 ; , s. 1053-1057
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Konferensbidrag (refereegranskat)abstract
- The paper considers a problem of minimizing the total number of labels that are necessary to realize a given set of end-to-end connections in a GMPLS transport network where traffic is handled by means of Label Switched Paths-connections established using the label switching principle. The problem is important for the networks where labels are a scarce/expensive resource, like in optical networks. We formulate an appropriate mixed-integer programming problem and discuss the ways it can be approached by the commercial solvers. We illustrate the effectiveness of the solution with numerical examples.
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