| Space-time codes as an important research content in MIMO system, can provide higher transmission rate and better transmission performance in energy and bandwidth constrained fading channels. Traditional linear space-time codes, such as orthogonal space-time block codes and layered space-time codes can not reach optimal result at the same time. Linear dispersion codes design is flexible, and can simultaneously optimized the system capacity and diversity.Due to size constrains of mobile devices, the number of receive antennas is ofen less than the number of transmit antennas in mobile communication downlink. This thesis focuses the reaserch of linear dispersion codes in this case. So that the coding scheme has more practical value. This thsis presents a simple, common coding scheme, using trace-orthogonal criteria and full rank criteria, can achieve near optimal system capacity and full diversity gain.In the decoding context, this thsis focused on sphere decoding. QR ordered decomposition was introduced in the adjusting-radius sphere decoding to further reduce the docoding complexity. |
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