Threshold - Free Erasure Decoded Multicarrier Local Transmission over Multipath Channels

SUMMARY In order to exploit fully the frequency diversity benefits of multicarrier modulation (MCM), and the very nature of the frequency selective radio channel, we investigate an erasure decoded π/4 QDPSK MCM (ED-MCM) by employing simple Hamming (block) code. We propose the threshold-free criteria, i.e. relative minimum receive power test (RMRPT) and relative maximum decision error test (RMDET) for erasure generation and evaluate ED-MCM's performance by applying these tests to average received power, average decision error, instantaneous symbol/bit decision errors. At a normalized delay spread of 1/64, computer simulation results indicate a coding gains of 6.0-7.0 dB with ED-MCM at a BER of 10 –3. RMDET/RMRPT based erasure decoding yields a 1.5-2.5 dB improvement over the conventional forward error correction (FEC) decoding at a BER of 10 –5. The simulation results at other normalized delay spreads, i.e., 1/32, 1/16 are also obtained. The erasure criteria (RMRPT and RMDET) applied to average values of received power/ decision error yield consistently better performance over error only decoding. The results indicate that the erasure decoding based on relative (threshold-free) measures clearly promises an improved performance of the MCM system. key words: frequency selective fading, multicarrier modulation, relative (threshold-free) erasure generation, erasure decoding