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Träfflista för sökning "LAR1:cth ;pers:(Viberg Mats 1961);spr:eng;pers:(Coldrey Mikael 1972);conttype:(refereed)"

Sökning: LAR1:cth > Viberg Mats 1961 > Engelska > Coldrey Mikael 1972 > Refereegranskat

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  • Lioliou, Panagiota, 1982-, et al. (författare)
  • Efficient Channel Estimation Techniques for Amplify and Forward Relaying Systems
  • 2012
  • Ingår i: IEEE Transactions on Communications. - 1558-0857. ; 60:11, s. 3150-3155
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we present a channel estimation scheme for Amplify-and-Forward (AF) relaying systems, using measurements at the destination only. A Least-Squares (LS) based channel estimation algorithm is developed, that provides the destination with full knowledge of all channel responses involved in the transmission. To investigate the algorithm performance, the Cramer-Rao lower bound (CRB) is analytically computed and compared with the asymptotic covariance of the proposed estimator. Since the existing estimator does not reach the CRB, we also propose and analyze an improved algorithm by taking into account the noise characteristics via weighted LS (WLS). The improved algorithm is asymptotically efficient, since it attains the CRB as the SNR tends to infinity.
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  • Lioliou, Panagiota, 1982-, et al. (författare)
  • Self-Interference Suppression in Full-Duplex MIMO Relays
  • 2010
  • Ingår i: 44th Asilomar Conference on Signals, Systems and Computers. - 1058-6393. - 978-142449721-8 ; s. 658-662
  • Konferensbidrag (refereegranskat)abstract
    • Full-duplex relays can provide cost-effective cover-age extension and throughput enhancement. However, the main limiting factor is the resulting self-interference signal which deteriorates the relay performance. In this paper, we propose a novel technique for self-interference suppression in full-duplex Multiple-Input Multiple-Output (MIMO) relays. The relay employs transmit and receive weight filters for suppressing the self-interference signal. Unlike existing techniques that are based on zero forcing of self-interference, we aim at maximizing the ratio between the power of the useful signal to the self-interference power at the relay reception and transmission. Our simulation results show that the proposed algorithm outperforms the existing schemes since it can suppress interference substantially with less impact on the useful signal.
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  • Seifi, Nima, 1981-, et al. (författare)
  • An Efficient Signaling for Multi-mode Transmission in Multi-user MIMO
  • 2010
  • Ingår i: IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP'10), Dallas, USA, Mar. 2010.. - 1520-6149. - 978-142444296-6 ; s. 3402-3405
  • Konferensbidrag (refereegranskat)abstract
    • In this paper the downlink of a multi-user MIMO (MUMIMO) system with multi-mode transmission is considered. We propose a low-complexity algorithm for selecting users and the corresponding number of data streams to each user, denoted as user transmission mode (UTM). The selection is only based on the average received signal-to-noise ratio (SNR) from the base station (BS) for each user. This reduces the overall amount of feedback for scheduling, as opposed to techniques that assume perfect instantaneous channel state information (CSI) from all users. Analytical average throughput approximations are derived for each user at different UTMs. Simulation results demonstrate that the proposed algorithm provides performance close to dirty paper coding (DPC) with considerably reduced feedback.
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  • Seifi, Nima, 1981-, et al. (författare)
  • Coordinated Single-Cell vs Multi-Cell Transmission with Limited-Capacity Backhaul
  • 2010
  • Ingår i: IEEE Asilomar Conf. on Signals, Systems, and Computers, Pacific Grove, CA, Nov. 2010.
  • Konferensbidrag (refereegranskat)abstract
    • Base station coordination is an efficient technique to transcend the limits on spectral efficiency imposed by intercell interference. In this paper, we compare the performance of different coordination strategies with different amount of channel state information (CSI) and data sharing among the coordinating base stations. We focus on the effect of limited backhaul capacity in a two-cell network. Contrary to the common belief, we show that coordination strategies with no data and only limited CSI sharing is preferred to those with full data and CSI sharing when the backhaul capacity is relatively low and the edge SNR is high.
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  • Seifi, Nima, 1981-, et al. (författare)
  • Multimode Transmission in Network MIMO Downlink with Incomplete CSI
  • 2011
  • Ingår i: EURASIP Journal on Advances in Signal Processing, special issue on Cooperative MIMO Multicell Networks, 2011. - 1687-6172.
  • Tidskriftsartikel (refereegranskat)abstract
    • We consider a cooperative multi-cell MIMO (a.k.a network MIMO) downlink system with multiantenna base stations (BSs), which are connected to a central unit and communicate with multi-antenna users. In such a network, obtaining perfect channel state information (CSI) of all users at the central unit to exploit opportunistic scheduling requires a substantial amount of feedback and backhaul signaling. In this paper, we propose a scheduling algorithm based only on the knowledge of the average received SNR at each user from all the cooperating BSs, denoted as incomplete CSI. Multi-mode transmission is applied that is able to adaptively adjust the number of data streams transmitted to each user. Utilizing the results of random matrix theory, an analytical framework is proposed to approximate the ergodic rate of each user with different number of data streams. Using these approximate ergodic rates, a joint user and mode selection algorithm is proposed, where only the scheduled users need to feed back instantaneous CSI. Simulation results demonstrate that the developed analytical framework provides a good approximation for a practical number of antennas. While substantially reducing the feedback overhead, it is shown that the proposed scheduling algorithm performs closely to the opportunistic scheduling algorithm that requires instantaneous CSI feedback from all users.
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  • Resultat 1-9 av 9
 
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