Title :
Iterative channel estimation for MC-CDMA
Author :
Sand, Stephan ; Raulefs, Ronald ; Auer, Gunther
Author_Institution :
German Aerosp. Center, Wessling, Germany
fDate :
30 May-1 June 2005
Abstract :
We investigate the performance of a downlink multi-carrier code division multiple access (MC-CDMA) system employing a receiver with iterative channel estimation (ICE). The MC-CDMA system transmits several data symbols per user and per orthogonal frequency division multiplexing (OFDM) symbol in parallel, with each data symbol being spread with a Walsh-Hadamard code. Due to the superposition of spread data signals (chips), zero-valued subcarriers can occur, which cannot be used to compute least-squares (LS) channel estimates in ICE. Therefore, we propose the modified LS and minimum mean square error (MMSE) channel estimation methods to overcome this problem and to avoid noise enhancement in ICE. We compare both methods through simulations and investigate the robustness of ICE with both methods if the channel statistics are not known perfectly.
Keywords :
Hadamard codes; OFDM modulation; channel estimation; code division multiple access; iterative methods; least mean squares methods; mobile radio; MC-CDMA downlink; MMSE channel estimation; Walsh-Hadamard code; channel statistics; iterative channel estimation; least-squares channel estimates; minimum mean square error; mobile channels; multi-carrier code division multiple access downlink; noise enhancement avoidance; orthogonal frequency division multiplexing; spread data signals; zero-valued subcarriers; Channel estimation; Computational modeling; Downlink; Ice; Mean square error methods; Multicarrier code division multiple access; Noise robustness; OFDM; Quantum computing; Statistics;
Conference_Titel :
Vehicular Technology Conference, 2005. VTC 2005-Spring. 2005 IEEE 61st
Print_ISBN :
0-7803-8887-9
DOI :
10.1109/VETECS.2005.1543335
