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The goal of this article is to discuss the implementation of two cooperative protocols - decode-and-forward (DF) and estimate-and-forward (EF). In each case, the starting point is an information theoretic random coding scheme, which motivates a practical code construction. Low-density parity check (LDPC) codes are used as components in both protocols. In DF relaying, the problem boils down to a search for multi-rate LDPC codes that simultaneously perform well for the source-relay and the source- destination links. On the other hand, in EF relaying, the challenge is to design an efficient quantizer for forming a compressed estimate at the relay. The performance of each scheme is comparable to theoretical limits.