Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/11

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Author: search.filters.author.Özbek, BernaPublisher: search.filters.publisher.John Wiley and Sons Inc.

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  • Article
    Citation - Scopus: 1
    On Stream Selection for Interference Alignment With Limited Feedback in Heterogeneous Networks
    (John Wiley and Sons Inc., 2016) Aycan, Esra; Özbek, Berna; Le Ruyet, Didier
    This paper presents a stream selection based interference alignment approach with imperfect channel state information for heterogeneous networks. The proposed solution constructs stream sequences by selecting only the strongest stream of each user where the first stream of the constructed stream sequences is associated to a pico user. While selecting the streams, the channel matrices of the unselected streams are projected orthogonally to the virtual transmit and receive channels of the selected stream in order to align the interference in the null space of these virtual channels. In addition, the influence of imperfect channel state information on the proposed algorithm is analysed. A bit allocation scheme is given by deriving an upper bound on the rate loss because of quantisation. The simulation results are carried out by considering various scenarios with different locations of pico cells at the cell edge regions of the macro cell. The performance results show that the proposed algorithm with the imperfect channel state information achieves higher performance than the existing algorithms.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Reduced Feedback Load Using User Selection Algorithms for the Multiuser Multi-Input Single-Output Systems
    (John Wiley and Sons Inc., 2013) Khanfir, Hajer; Le Ruyet, Didier; Özbek, Berna
    Locate full-text(opens in a new window)|Full Text(opens in a new window)|View at Publisher| Export | Download | Add to List | More... Transactions on emerging telecommunications technologies Volume 24, Issue 7-8, November-December 2013, Pages 809-819 Reduced feedback load using user selection algorithms for the multiuser multi-input single-output systems (Article) Khanfir, H.a , Le Ruyet, D.a, Özbek, B.b a Electronics and Communications Laboratory, CNAM, 292 Rue Saint Martin, 75141, Paris, France b Electrical and Electronics Engineering Department, Izmir Institute of Technology, Urla, 35430, Izmir, Turkey View references (27) Abstract For wireless multiuser multi-input single-output communication systems with adaptive scheduling and precoding, the users have to feed back their channel state information. However, the amount of feedback data increases with the number of users and the number of transmit antennas. In this paper, we propose a criterion based on the orthogonality between the users' channels to reduce this uplink load. Without cooperation between the users, we only allow users that are semi-orthogonal to feed back their quantized channel information to the base station. We propose a lower bound on the sum rate for the proposed criterion. We show that the performance is almost independent of the number of quantized channel quality information and only channel direction information is important at the transmitter. Then, we consider a noisy feedback channel and propose an algorithm to reduce the noise effect on the analogue feedback