Precoding by pairing subchannels to increase MIMO capacity with discrete input alphabets

Mohammed, Saif Khan ; Viterbo, Emanuele ; Hong, Yi ; Chockalingam, Ananthanarayanan (2011) Precoding by pairing subchannels to increase MIMO capacity with discrete input alphabets IEEE Transactions on Information Theory, 57 (7). pp. 4156-4169. ISSN 0018-9448

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Official URL: http://ieeexplore.ieee.org/document/5895100/

Related URL: http://dx.doi.org/10.1109/TIT.2011.2146050

Abstract

We consider Gaussian multiple-input multiple-output (MIMO) channels with discrete input alphabets. We propose a non diagonal precoder based on the X-Codes in to increase the mutual information. The MIMO channel is transformed into a set of parallel subchannels using singular value decomposition (SVD) and X-Codes are then used to pair the subchannels. X-Codes are fully characterized by the pairings and a 2 × 2 real rotation matrix for each pair (parameterized with a single angle). This precoding structure enables us to express the total mutual information as a sum of the mutual information of all the pairs. The problem of finding the optimal precoder with the above structure, which maximizes the total mutual information, is solved by: i) optimizing the rotation angle and the power allocation within each pair and ii) finding the optimal pairing and power allocation among the pairs. It is shown that the mutual information achieved with the proposed pairing scheme is very close to that achieved with the optimal pre coder by Cruz et al., and is significantly better than Mercury/waterfllling strategy by Lozano et al. Our approach greatly simplifies both the precoder optimization and the detection complexity, making it suitable for practical applications.

Item Type:Article
Source:Copyright of this article belongs to Institute of Electrical and Electronics Engineers.
Keywords:Singular Value Decomposition (SVD); Condition Number; Multiple-Input Multiple-Output (MIMO); Mutual Information; Orthogonal Frequency Division Multiplexing (OFDM); Precoding
ID Code:100613
Deposited On:28 Mar 2017 09:37
Last Modified:28 Mar 2017 09:37

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