Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

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    Erratum To: on Stream Selection for Interference Alignment in Heterogeneous Networks
    (Springer Verlag, 2016) Aycan, Esra; Özbek, Berna; Le Ruyet, Didier
  • Article
    Citation - WoS: 3
    Citation - Scopus: 5
    On stream selection for interference alignment in heterogeneous networks
    (Springer Verlag, 2016) Aycan, Esra; Özbek, Berna; Le Ruyet, Didier
    This paper proposes a stream selection algorithm to deal with the interference and increase the sum capacity in the context of heterogeneous networks where cells of different types coexist. Due to the different transmit powers between the macro and small cells, interference levels are also different. Since the small cells are densely deployed, fully connected interference network between small cells is considered in this paper. The proposed algorithm performs the selection of a stream sequence among a predetermined set of sequences. Those selected sequences are the ones that mostly contribute to the sum rate when performing the exhaustive search. As a consequence, since the search space is reduced, the complexity is significantly decreased. These stream sequences form a regular structure where the first stream is associated to a pico user. Another distinguishing property of the proposed approach is that the stream sequences include at least one stream for each user. When selecting the streams, the channel matrices of the unselected streams are projected orthogonally to the virtual transmit and virtual receive channels of the selected stream in order to align the interference in the null space of these virtual channels. The performance evaluations are carried out by considering different scenarios with different numbers and locations of pico cells. It is shown that the proposed method can significantly reduce the computational complexity while achieving a very close performance to the exhaustive search.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 9
    Adaptive Limited Feedback Links for Cooperative Multi-Antenna Multicell Networks
    (Springer Verlag, 2014) Özbek, Berna; Ruyet, Didier Le
    The overall performance of cooperative networks is quite sensitive to channel state information (CSI) of serving and interfering base stations (BSs) and affected strongly by quality of limited feedback links. In this paper, we propose two adaptive limited feedback strategies for intercell interference cancelation in multi-antenna multicell networks. The first proposed strategy is developed to improve average multicell capacity assuming a fixed rate feedback link. This algorithm is based on adaptation of the number of bits to quantize CSI of serving and interfering BSs according to transmitter power and location of the user in its own cell. The second proposed strategy is designed in a way to increase average capacity of cell-edge users assuming an adaptive rate feedback link. This algorithm is based on the idea of allocating more bits to quantize CSI of users at cell-edge regions while allocating less bits for users near the serving BS. We illustrate performance of the proposed feedback links for downlink cooperative multi-antenna multicell networks in wireless channels.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Wavelet Ridges for Musical Instrument Classification
    (Springer Verlag, 2012) Özbek, Mehmet Erdal; Özkurt, Nalan; Savacı, Ferit Acar
    The time-varying frequency structure of musical signals have been analyzed using wavelets by either extracting the instantaneous frequency of signals or building features from the energies of sub-band coefficients. We propose to benefit from a combination of these two approaches and use the time-frequency domain energy localization curves, called as wavelet ridges, in order to build features for classification of musical instrument sounds. We evaluated the representative capability of our feature in different musical instrument classification problems using support vector machine classifiers. The comparison with the features based on parameterizing the wavelet sub-band energies confirmed the effectiveness of the proposed feature. © 2011 Springer Science+Business Media, LLC.