Low complexity decoding of a class of linear space-time block codes by subspace partitioning

Future broadband wireless communication systems will be characterized by heterogeneity with regard to node capabilities, link level requirements, cell structures etc. High carrier frequencies and large system bandwidth will make extreme diversity factors feasible. We consider a recently proposed class of linear space-time block codes (and associated decoders), which meet the requirements of future communication systems. In the case of these codes an increase of the block length can lead to higher diversity factors but the required decoder complexity increases too. It is not always possible for the transmitter to adapt the used block length to the decoder complexity of every receiver (e.g. for a broadcast transmission or if the transmitter has no knowledge about the receiver complexity), especially when high diversity gains are favorable. In this paper we present an approach to low complexity decoding by subspace partitioning. So, if a transmitter uses large block lengths, low complexity nodes can handle these blocks and achieve moderate diversity gains while nodes with higher capabilities can profit from high diversity gains.