Frequency synchronization and channel equalization for an OFDM-IDMA uplink systemReport as inadecuate

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1 IMS - Laboratoire de l-intégration, du matériau au système

Abstract : This paper deals with a system combining orthogonal frequency di- vision multiplexing OFDM and interleave-division multiple access IDMA. OFDM makes the system robust against intersymbol inter- ference, whereas IDMA combats the multiple access interference. Nevertheless, unwanted phenomena must be taken into account: 1- carrier frequency offset CFO must be estimated-corrected to guarantee the orthogonality between subcarriers and hence the sym- bol detection in the system. 2- the conventional iterative IDMA receiver, initially proposed by Ping et al., requires a priori knowl- edge of the multipath channel. Therefore, the CFO and the multipath channel must be estimated -accurately- in an OFDM-IDMA system. Our contribution is to propose a new scheme where a CFO correc- tion is no longer necessary, unlike common OFDM approaches. We show that without a CFO correction, the symbols transmitted by the different users can be recovered by modifying the conventional iterative architecture of the IDMA receiver. When considering an OFDM-IDMA network over different Rayleigh fading channels, simulation results clearly show the efficiency of the proposed algorithm in terms of estimation accuracy and bit error rate.

Keywords : OFDM-IDMA CFO-channel correction CFO- channel estimation sigma-points Kalman filter

Author: Hector Poveda - Guillaume Ferré - Eric Grivel -



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