Channel Estimation for Capacity Maximization in OFDM systems

The channel estimation techniques based on pilot arrangement for OFDM systems are investigated in this book. The channel estimation based on block type pilot arrangement is performed by sending pilots at every sub-channel and using this estimation for a fixed number of symbols. The channel for block-type pilot arrangement is estimated by Least Square (LS) or Minimum Mean-Square (MMSE) estimators. The channel estimation based on comb type pilot arrangement is performed by inserting pilot tones into each OFDM symbol. The channel estimation based on comb type pilot arrangement is studied and implemented through different algorithms for both estimating and interpolating the channel. The channel interpolation is done using linear interpolation, second order interpolation, low-pass interpolation, spline cubic interpolation and time domain interpolation. We have also implemented decision feedback equalizer for all sub-channels to reduce the bit error rate. We have compared the performances of all schemes by measuring bit error rate with 16QAM, 32QAM, 64QAM, 128QAM and 256QAM as modulation schemes and Rayleigh as channel model.