In recent years, cooperative communication is a hot topic of research and it is a powerful physical layer technique to combat fading in wireless relaying scenario. Concerning with the physical layer issues, in this paper it is focussed on with providing a better space time block coding (STBC) scheme and incorporating it in the cooperative relaying nodes to upgrade the system performance. Recently, the golden codes have proven to exhibit a superior performance in a wireless MIMO (Multiple Input

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... ultiple Output) scenario than any other code. However, a serious limitation associated with it is its increased decoding complexity. This paper attempts to resolve this challenge through suitable modification of golden code such that a less complex sphere decoder could be used without much compromising the error rates. The decoder complexity is analyzed through simulation and it proves to exhibit less complexity compared to the conventional (Maximum likelihood) ML decoder. The single relay cooperative STBC consisting of source, relay and destination are considered. The cooperative protocol strategy considered in the relay node is Decode and forward (DF) protocol. The proposed modified golden code with less complex sphere decoder is implemented in the nodes of the cooperative relaying system to achieve better performance in the system. The simulation results have validated the effectiveness of the proposed scheme by offering better BER performance, minimum outage probability and increased spectral efficiency compared to the non cooperative transmission method. KEYWORDS Cooperative communication, cooperative STBC, Bit error rate (BER), outage probability, spectral efficiency, Golden code, low complex sphere decoder.