A Performance Analysis of Coded Frequency - Hopped OFDMA with Pilot-Assisted Channel Estimation

We investigate the performance of frequency-hopped OFDMA (FIH-OFDMA), where subearriers are assigned to users according to predetermined hopping patterns. Some of the patterns carry pilot symbols, which the users track to estimate their channel and perform coherent detection. We develop a simple theoretical framework in order to evaluate the bit error probability (BEP) over each data pattern, when trellis-coded modulation (TCM) is employed for error protection. Our analytical results illustrate that appropriately constructing the patterns, given the channel parameters, can have a significant effect on the performance experienced by different users of this OFDMA system. An intuitively pleasing trade-off between channel estimation quality and performance enhancement due to frequency diversity is also revealed, as the channel becomes more frequency selective.