Iterative decoding for reducing cyclic prefix requirement in OFDM modulation

Orthogonal frequency division multiplexing (OFDM) requires a cyclic prefix extension to combat the detrimental effects of excess delay in the channel. A cyclic prefix length of 25% of total OFDM symbol length is specified for next generation wireless local area network systems (IEEE standard 802.11a). Whilst combating multipath and enabling single tap equalisation in the frequency domain, the additional overhead has a detrimental effect on data throughput. Presented is the performance of low density parity check encoding at the transmitter and iterative (´turbo´) decoding at the receiver to remove the cyclic prefix. It is shown that with an initial log likelihood operation at the receiver, iterative decoding is able to overcome the intersymbol interference introduced by the channel.