Joint Detection and Channel Estimation for OFDM Signals with Implicit Pilots

Accurate channel estimation is mandatory for the performance of OFDM modulations (orthogonal frequency division multiplexing). For this purpose, pilot symbols and/or training sequences are usually multiplexed with data symbols. To avoid the spectral degradation associated to multiplexed pilots, the use of implicit pilots (i.e., pilots superimposed to data) was recently proposed. However, the interference levels between data and pilots might be very high, leading to performance degradation. In this paper we consider OFDM schemes where the channel estimation is based on implicit pilots. To overcome the difficulties inherent to the interference levels between pilots and data, we propose an iterative receiver with joint detection and channel estimation. Our performance results show that we can achieve performances close to the ones with perfect channel estimation, even when low-power pilots or sort frames are employed.