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Bandwidth efficient channel estimation for full duplex communication systems

In this paper, the channel estimation problem in full duplex (FD) point-to-point wireless communication systems is investigated. Because of the existence of two interfering and communication channels, this problem is fundamentally different from the conventional channel estimation problems in half duplex (HD) communication systems. Here, we propose a blind channel estimator that simultaneously estimates the channel parameters of the FD system without requiring time division duplex. A major problem for blind estimators is the identifiability of the parameters. Therefore, thorough analysis is presented to determine the identifiable parameters in this estimation problem. It will be shown that a completely blind estimator utilizing a symmetric modulation set suffers from phase ambiguity. For this reason, only the channel magnitudes can be estimated blindly. It is further presented that if the modulation set is not centered around the origin then this phase ambiguity can be resolved.