Retransmission of user's data at partner node in repetition based cooperative protocols decreases bandwidth efficiency and imposes overhead on cooperative signalling. In this paper we propose two full-duplex distributed cooperative protocols for OFDM systems, that improve BER performance and decrease overhead without any hardware changes in comparison with the conventional cooperative protocols. In the proposed full-duplex distributed cooperative system, the partner node retransmits a part of the information on high quality subcarriers that belong to the user's data instead of all received ones. An extensive Monte Carlo simulation study is presented to reveal the superior performance of the distributed decoding system as compared to that of the conventional cooperative schemes for the OFDM scheme.

This paper proposes an iterative detector for uncoded OFDM signals in cooperative networks, where the information symbols are simply partitioned through a time-domain matrix at the OFDM transmitter. We analytically show that our proposed iterative detector at the partner node converges and can completely recover the user's data from its partitioned version, if sufficient redundancy is inserted in the user's data. For efficient use of the redundancy in the user's data, a coded cooperative transmission based on superposition modulation is proposed. Additionally, a closed-form input-output relationship for the partitioning and reconstruction algorithm in the proposed cooperative scenario is derived. We also obtain closed-form expressions for symbol error rate performance of the proposed coded cooperative scenario over Rayleigh frequency-selective fading channels. Numerical comparisons shed light on the relative merits of the proposed coded cooperation under various inter-user and uplink channel conditions.