A Tight Bound on BER of MCIK-OFDM With Greedy Detection and Imperfect CSI

This letter first investigates bit error rate (BER) of Multi-Carrier Index Keying-Orthogonal Frequency Division Multiplexing using a low-complexity greedy detector (GD). We derive a tight, closed-form expression for the BER of the GD in the presence of channel state information (CSI) uncertainty. Particularly, exploiting the fact that the GD detects the active indices first, and then detects the data symbols, we divide the BER into two terms: the index BER and the symbol BER. The asymptotic analysis is also provided to analyze impacts of various CSI conditions on the BER. Interestingly, via theoretical and simulation results, we discover that the GD is not only less sensitive to imperfect CSI, but also better than the maximum likelihood detector under certain CSI conditions. In addition, the derived expression is accurate in a wide range of signal-to-noise ratio regions.