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arXiv · 1104.4607

Tree-Structured Random Vector Quantization for Limited-Feedback Wireless Channels

Wiroonsak Santipach·Kritsada Mamat
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Abstract

We consider the quantization of a transmit beamforming vector in multiantenna channels and of a signature vector in code division multiple access (CDMA) systems. Assuming perfect channel knowledge, the receiver selects for a transmitter the vector that maximizes the performance from a random vector quantization (RVQ) codebook, which consists of independent isotropically distributed unit-norm vectors. The quantized vector is then relayed to the transmitter via a rate-limited feedback channel. The RVQ codebook requires an exhaustive search to locate the selected entry. To reduce the search complexity, we apply generalized Lloyd or $k$-dimensional (kd)-tree algorithms to organize RVQ entries into a tree. In examples shown, the search complexity of tree-structured (TS) RVQ can be a few orders of magnitude less than that of the unstructured RVQ for the same performance. We also derive the performance approximation for TS-RVQ in a large system limit, which predicts the performance of a moderate-size system very well.

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Wiroonsak Santipach, Kritsada Mamat. 2011-07-08. Tree-Structured Random Vector Quantization for Limited-Feedback Wireless Channels. https://doi.org/10.1109/twc.2011.072511.101916

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