author = {C. Bockelmann and D. W\"{u}bben and K.-D. Kammeyer},
  year = {2008},
  month = {Feb},
  title = {Mutual Information based Rate Adaptation for MIMO-OFDM Systems with Finite Signal Alphabets},
  URL = {http://www.nt.tu-darmstadt.de/nt/Welcome.400.0.html},
  address={Darmstadt, Germany},
  abstract={We consider a single user MIMO-OFDM system where spatial multiplexing is applied and formulate rate allocation algorithms to adapt the used modulation alphabet on a per subcarrier basis. As a means to consider the system behavior including the channel code regarding bit or frame error rate (BER,FER) versus normalized average mutual information (NAMI) of an OFDM symbol for several M -QAM alphabets is investigated. To this end an approximation to the mutual information of MIMO systems with M-QAM signal alphabets is derived and compared to channel decomposition approaches to find a complexity/accuracy trade-off. Based on the mutual information results two algorithms using this channel knowledge are introduced. On the one hand, the error rates can be optimized assuming a fixed rate requirement and on the other hand the achieved transmission rate can be optimized under a BER/FER constraint. In both cases a NAMI threshold derived from the simulated system behavior for a specific channel code is used to adapt the allocated modulation alphabets via a greedy algorithm to achieve the target NAMI within an error margin.},
  booktitle={International ITG Workshop on Smart Antennas (WSA 08)}