Conference Paper

On the Rate Versus ML-Decoding Complexity Tradeoff of Square LDSTBCs with Unitary Weight Matrices

Univ. of Colorado at Boulder, Boulder, CO
DOI: 10.1109/GLOCOM.2008.ECP.237 Conference: Global Telecommunications Conference, 2008. IEEE GLOBECOM 2008. IEEE
Source: IEEE Xplore


The low decoding complexity structure of Linear Dispersion Space Time Block Codes (LDSTBCs) with unitary weight matrices is analyzed. It is shown that given n = 2alpha, the maximum number of groups in which the information symbols can be separated and decoded independently is (2a + 2), and as we lower the number of different groups to (2k + 2), 0 les k les alpha, we get higher rate codes. We also find the analytic expression for rates that such codes can achieve for any chosen group number, thus completely characterizing the rate-ML-decoding-complexity tradeoff for this class of codes. The proof of the result also includes a method for constructing such optimal rate achieving codes. Interestingly, this analysis produces some low decoding complexity codes with rate greater than one.

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    ABSTRACT: A new unequal-error-protected space-time block code (UEP-STBC) is designed in this paper for multimedia transmission systems deployed with multiple antennas. Traditionally, a space-time code is designed to support a single information stream aiming to achieve a point on the fundamental rate versus diversity tradeoff curve, while this proposed class of codes has the capability of transmitting different performed symbols from different layers within the same codeword. The UEP-STBC, whose symbols belong to different orthogonal layers without interference, is fit for the systems using scalable video coding (SVC) as the source coding. The design covers the cases of arbitrary number of transmit antennas. The simulation results demonstrate the performance advantage and coverage enhancement of the proposed codes in multimedia transmission over conventional codes.
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