Title :
Totally blind APP channel estimation for mobile OFDM systems
Author :
Sanzi, Frieder ; Necker, Marc C.
Author_Institution :
Inst. of Telecommun., Univ. of Stuttgart, Germany
Abstract :
A new two-dimensional blind channel estimation scheme for coherent detection of orthogonal frequency-division multiplexing (OFDM) signals in a mobile environment is presented. The channel estimation is based on the a posteriori probability (APP) calculation algorithm. The time-variant channel transfer function is completely recovered without phase ambiguity with no need for any pilot or reference symbols, thus maximizing the spectral efficiency of the underlying OFDM system. The phase ambiguity problem is solved by using a 4-QAM (quadrature amplitude modulation) scheme with asymmetrical arrangement. The results clearly indicate that totally blind channel estimation is possible for virtually any realistic time-variant mobile channel.
Keywords :
OFDM modulation; channel estimation; iterative decoding; mobile radio; probability; quadrature amplitude modulation; signal detection; time-varying channels; 4-QAM; a posteriori probability; asymmetrical arrangement; blind APP channel estimation; coherent detection; iterative decoding; mobile OFDM systems; orthogonal frequency-division multiplexing; phase ambiguity problem; quadrature amplitude modulation; spectral efficiency; time-variant channel transfer function; two-dimensional blind channel estimation; Blind equalizers; Channel estimation; Finite impulse response filter; Frequency division multiplexing; Frequency estimation; Iterative decoding; OFDM; Probability; Quadrature phase shift keying; Transfer functions;
Journal_Title :
Communications Letters, IEEE
DOI :
10.1109/LCOMM.2003.820085
