In this paper, a novel and practical transmission scheme for a Multiple Input Multiple Output-Orthogonal Frequency Division Multiple Access (MIMO-OFDMA) relaybased network is proposed and evaluated. We coin the term Virtual Maximum Ratio Transmission (VMRT) for the scheme which obtains diversity and array gain at both links in a two-hop transmission, while keeping the complexity low. Besides, the requirements of Channel State Information needed at the different network elements such as the Base

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... Station, Relay Station or User Terminals are also limited, and so the feedback. The obtained global performance by using proposed VMRT outperforms other schemes. Diversity gains larger than 6 can be easily obtained with a reduced number of relays. For this reason, VMRT is a good candidate to achieve high speed transmission or increase coverage and reliability in slow varying channels for relay-based networks. Keywords MIMO-OFDMA · Beamforming · Virtual STBC · Virtual maximum ratio transmission Introduction The rapid growth in wireless access and its applications have generated a high demand to provide data rate, coverage and reliability. Multiple-Input Multiple-Output (MIMO) This work has been partly funded by the Spanish government with projects MACAWI (TEC 2005-07477-C02-02), MULTIADAPTIVE (TEC 2008-06327-C03-02), COMONSENS (CDS2008-00010) and CODIV (ICT-2007-215477).