Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Conference Object Performance of Multicast Miso-Ofdm Systems(Ecole Nationale Superieure de Techniques Avancees, ENSTA, 2020) Le Ruyet, Didier; Özbek, Berna; Khanfir, HajerIn this paper, we evaluate the performance of multicast OFDM systems with single and multiple transmit antennas. We have shown that it is possible to increase the data rate of multicast OFDM systems by selecting the users with good channel for each subcarrier. For the single transmit antenna case, the resource allocation has been applied using the two-step algorithm where subcarrier allocation and bit loading are performed separately. For the multiple transmit antennas case, we have proposed a suboptimal algorithm using a set of precoding vectors. In this study, we present the simulation results of the complete transmission chain where we have associated the resource allocation algorithms with a powerful erasure code. The results show that the proposed algorithms outperform the classical worst case algorithm for both single and multiple transmit antennas. © EW 2007 - 13th European Wireless Conference: Enabling Technologies for Wireless Multimedia Communications. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 8Performance Evaluation of Multicast Miso-Ofdm Systems(Springer Verlag, 2008) Özbek, Berna; Le Ruyet, Didier; Khanfir, HajerIn 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.Conference Object Citation - WoS: 6Citation - Scopus: 11Adaptive Resource Allocation for Multicast Ofdm Systems With Multiple Transmit Antennas(Institute of Electrical and Electronics Engineers Inc., 2006) Özbek, Berna; Le Ruyet, Didier; Khiari, HajerWe evaluate the impact of multiple transmit antennas on the performance of multicast OFDM systems by proposing a suboptimal low complexity algorithm. Associated with a powerful erasure code, it is possible to increase the data rate of multicast OFDM systems by selecting for each subcarrier to the users with a good channel condition. We show that the resource allocation which includes the precoding vector selection, subcarrier allocation and bit loading is a difficult optimization problem. We propose a suboptimal algorithm to solve this problem by avoiding the optimization to reduce complexity. When the users are not symmetrically distributed around the base station, we add a fair scheduler to guarantee that each user receives the same amount of data. We present simulation results where we compare the proposed multicast systems with the classical multicast OFDM systems. When the users are symmetrically distributed around the base station, the gain is rather small, whereas when the users are non-symmetrically distributed, the proposed algorithm outperforms OFDM systems with subcarrier allocation.