%0 Journal Article %T Effects of Channel Estimation on Multiuser Virtual MIMO-OFDMA Relay-Based Networks %A Gil Jim¨¦nez V¨ªctorP %A Ribeiro Carlos %A Gameiro Atilio %A Armada AnaGarc¨ªa %J EURASIP Journal on Wireless Communications and Networking %D 2010 %I Springer %X A practical multiuser cooperative transmission scheme denoted as Virtual Maximum Ratio Transmission (VMRT) for multiple-input multiple-output-orthogonal frequency division multiple access (MIMO-OFDMA) relay-based networks is proposed and evaluated in the presence of a realistic channel estimation algorithm and using low-density parity-check (LDPC) codes. It is shown that this scheme is robust against channel estimation errors. It offers diversity and array gain, keeping the complexity low with a multiuser and multiantenna channel estimation algorithm that is simple and efficient. In addition, the combination with LDPC codes provides improved gains; diversity gains larger than 6 dB can be easily obtained with a reduced number of relays. Thus, this scheme can be used to extend coverage or increase system throughput by using simple cooperative OFDMA-based relays. %U http://jwcn.eurasipjournals.com/content/2010/764784