A New Joint Estimation of Channels and the Number of Transmit Antennas for OFDM Systems with Antenna Diversity Employing Walsh Hadamard Codes

Wichai PONGWILAI  Ryuji KOHNO  Sawasd TANTARATANA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E87-B   No.2   pp.242-256
Publication Date: 2004/02/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
Keyword: 
orthogonal frequency division multiplexing,  antenna diversity,  channel estimation,  

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Summary: 
We propose a new approach associated with the use of some selected sets of Walsh Hadamard codes for joint estimation of channels and the number of transmit antennas by employing only one OFDM pilot symbol. This allows transmit antenna diversity to be applied in systems which have a limited number of training symbols (preambles), e.g. HIPERLAN/2. The proposed approach does not require any a priori knowledge about the number of transmit antennas, providing flexibility in the number of antennas to be used. In addition, adaptive scheme associated with the proposed approach provides more accurate estimations of the channels. The effectiveness of the proposed approach is evaluated through simulation. Results show that the proposed scheme provides significant improvement over previous channel estimation schemes and has almost the same performance as the ideal system with the full knowledge of the channel state information.