Two training sequence based transmission schemes are proposed for the two-way relaying network when distributed concatenated space-time block code (DC-STBC) is employed, which lead to two channel estimation methods, i.e., the concatenated channel estimation and separated channel estimation. Theoretical mean square error (MSE) expressions are derived for both estimation methods when least square (LS) estimation is considered. Simulations on symbol error rate (SER) indicate that the separated channel estimation scheme is superior to the concatenated channel estimation scheme at a cost of larger complexity.