Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

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

Browse

Filters

2008 - 200912010 - 201942020 - 20211

Settings

Author: search.filters.author.Le Ruyet, DidierWoS Q: search.filters.wosQuartile.Q3

Search Results

Now showing 1 - 6 of 6
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Deep Learning Based Adaptive Bit Allocation for Heterogeneous Interference Channels
    (Elsevier, 2021) Aycan, Esra; Özbek, Berna; Le Ruyet, Didier
    This paper proposes an adaptive bit allocation scheme by using a fully connected (FC) deep neural network (DNN) considering imperfect channel state information (CSI) for heterogeneous networks. Achieving an accurate CSI has a crucial role on the system performance of the heterogeneous networks. Different quantization techniques have been employed to reduce the feedback overhead. However, the system performance cannot increase linearly with the number of bits increasing exponentially. Since optimizing the total number of bits is too complex for the entire network, an initial step is performed to distribute the bits to each cell in the conventional method. Then, the distributed bits are further allocated to each channel optimally. In order to enable direct allocation for the entire network, a FC-DNN based method is presented in this study. The optimized number of bits can be directly obtained for a different number of bits and scenarios by the proposed approach. The simulations are performed by using various scenarios with different allocation schemes. The performance results show that the DNN based method achieves a closer performance to the conventional approach. (C) 2021 Elsevier B.V. All rights reserved.
  • Other
    Erratum To: on Stream Selection for Interference Alignment in Heterogeneous Networks
    (Springer Verlag, 2016) Aycan, Esra; Özbek, Berna; Le Ruyet, Didier
  • 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: 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: 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
  • Article
    Citation - WoS: 7
    Citation - Scopus: 8
    Performance Evaluation of Multicast Miso-Ofdm Systems
    (Springer Verlag, 2008) Özbek, Berna; Le Ruyet, Didier; Khanfir, Hajer
    In this paper, we analyze the performance of multicast orthogonal frequency division multiplexing (OFDM) systems with single and multiple transmit antennas. We show that the resource allocation that includes the subcarrier allocation, bit loading, and the precoding vector selection in the multiple-input single-output (MISO) case is a difficult optimization problem. Consequently, we propose suboptimal algorithms based on the maximization of the sum data rate and the maximization of the minimum user data rate criteria. For practical application, we consider a complete transmission chain by combining powerful erasure codes with the proposed algorithms. Using this scheme, we guarantee that each user receives the same amount of information to decode the same data. Simulation results show that, for both single-input single-output (SISO)-OFDM and MISO-OFDM cases, the proposed multicast OFDM systems achieve gains over the worst user case algorithm.