Codebooks in Flag Manifolds for Limited Feedback MIMO Precoding
Konferenz: SCC 2013 - 9th International ITG Conference on Systems, Communication and Coding
21.01.2013 - 24.01.2013 in München, Deutschland
Tagungsband: SCC 2013
Seiten: 5Sprache: EnglischTyp: PDF
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Autoren:
Pitaval, Renaud-Alexandre; Srinivasan, Ashvin; Tirkkonen, Olav (Aalto University, Department of Communications and Networking, Espoo, Finland)
Inhalt:
We consider unitary codebook design problems for various precoded MIMO scenarios, and interprete them as generalized discretization problems of flag manifolds. As a concrete example, we consider codebooks for MIMO transmission with linear receivers. In this case, the problem reduces to discretizing permutation-invariant flag manifolds. A corresponding Lloyd algorithm is given, providing low-distortion codebooks. The achievable rate of the system applying the generated codebooks is compared by simulations. We find that for a N-by-N full-rank MIMO system with N > 2 and a linear receiver, the gain of precoding with a small number of feedback bits is small. This differs from the behavior of low-rank transmissions, where it is known that a small number of feedback bits allows near-optimal channel adaptation.