On the Spectral Efficiency of Blind Channel Estimation and Synchronization Techniques

Abstract

In the literature, channel estimation and synchronization (CE/SY) algorithms are classified as blind, and hence spectrally efficient, if they do not require pilot symbols. However, we show in this letter that such classification is not accurate and can be misleading. Consequently, this letter presents a more reliable and accurate approach to evaluate the spectral efficiency of communications systems with various CE/SY algorithms. The proposed approach allows fair spectral efficiency comparison between various systems with blind or non-blind CE/SY algorithms. In particular, we evaluate the spectral efficiency of communications systems that incorporates blind CE/SY algorithms and compare it to other blind and pilot-based algorithms. The obtained results reveal that, on the contrary to what is widely accepted, blind CE/SY algorithms with modulation-type constrain do not necessarily improve the spectral efficiency as compared to pilot-based techniques. Consequently, such techniques are classified as conditionally blind, to distinguish them from fully blind techniques.