Blind receiver for OFDM systems via sequential Monte Carlo in factor graphs

INTRODUCTION Orthogonal frequency division multiplexing(OFDM) is generally known as an effective techniquefor high data rates and has been adopted by standardssuch as Digital Audio and Video Broadcasting (DABand DVB) (ETSI, 1994; 1997). OFDM is robustagainst frequency selectivity of a multipath channeland the single-tap equalization can be used to detectthe transmitted symbols if frequency-selective fadingchannels are known. Although, the use of pilot tonesis the most robust way …

Blind receiver for OFDM systems via sequential Monte Carlo in factor graphs

Estimation and detection algorithms for orthogonal frequency division multiplexing (OFDM) systems can be de-veloped based on the sum-product algorithms, which operate by message passing in factor graphs. In this paper, we apply the sampling method (Monte Carlo) to factor graphs, and then the integrals in the sum-product algorithm can be approximated by sums, which results in complexity reduction. The blind receiver for OFDM systems can be derived via Sequential Monte Carlo (SMC) in factor graphs, the previous SMC blind receiver can be regarded as the special case of the sum-product algorithms using sampling methods. The previous SMC blind receiver for OFDM systems needs generating samples of the channel vector assuming the channel has an a priori Gaussian distribution. In the newly-built blind receiver, we generate samples of the virtual-pilots instead of the channel vector, with channel vector which can be easily computed based on virtual-pilots. As the size of the vir-tual-pilots space is much smaller than the channel vector space, only small number of samples are necessary, with the blind de-tection being much simpler. Furthermore, only one pilot tone is needed to resolve phase ambiguity and differential encoding is not used anymore. Finally, the results of computer simulations demonstrate that the proposal can perform well while providing sig-nificant complexity reduction.