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Maximum rank distance codes and their use in STBC-OFDM system design |
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| รหัสดีโอไอ | |
| Title | Maximum rank distance codes and their use in STBC-OFDM system design |
| Creator | Arslan Khalid |
| Contributor | Prapun Suksompong, Advisor |
| Publisher | Thammasat University |
| Publication Year | 2568 |
| Keyword | Wireless communications, Multiple-input multiple-output (MIMO), Space-time block codes (STBCs), Channel estimation, Maximum rank distance (MRD) codes, Orthogonal frequency division multiplexing (OFDM) |
| Abstract | Achieving reliable multiple-input multiple-output (MIMO) wireless communications without sacrificing transmission rate is a central challenge in space-time block code (STBC) design. STBCs over maximum rank distance (MRD) codes (MRD-STBCs) offer a framework that guarantees full diversity with unity code rate for arbitrary numbers of transmit antennas. However, the impact of specific finite field primitive polynomials on their error performance and robustness to imperfect channel state information (CSI) remains underexplored. This research optimizes MRD-STBCs through polynomial selection, evaluates robustness to estimation errors, and integrates them into OFDM architectures. First, a simulation-based framework is developed to identify optimal primitive polynomials. By evaluating candidate pools via exhaustive search, this study identifies specific, unique polynomials whose MRD-STBCs yield superior error performance compared to the polynomials adopted in prior studies. The optimized polynomials achieve approximately 50% error reduction at high signal-to-noise ratio (SNR), confirming that polynomial selection is a prerequisite for superior performance. Second, the robustness of optimized MRD-STBCs is evaluated for two-antenna systems with imperfect CSI. Using pilot-aided linear minimum mean square error (MMSE) estimation with fixed transmission rates and pilot overhead, the system is benchmarked against the Alamouti and Golden codes. Results show that complex MRD-STBC codewords yield pilots with orthogonal columns, minimizing mean square error (MSE). Consequently, the MRD-STBC estimation accuracy matches that of the Alamouti code and outperforms the Golden code. Although the Golden code excels under perfect CSI, it suffers a performance bottleneck at high SNR (>15 dB) due to its non-orthogonal pilot. In contrast, MRD-STBCs remain robust and outperform the Golden code under imperfect CSI at high SNR. Furthermore, the orthogonal Alamouti code exhibits superior error performance in this 2×2 configuration; however, its generalization suffers a rate loss with more than two antennas. In contrast, MRD-STBCs maintain a unity code rate regardless of the number of antennas, offering a high-rate alternative.Finally, optimized MRD-STBCs are integrated into orthogonal frequency division multiplexing (OFDM) architectures. The resulting MRD-STBC-OFDM and its wavelet-based variant demonstrate data rate improvements of up to 33.3% over conventional orthogonal STBC-OFDM for configurations with more than two antennas. However, these improvements come at the cost of increased computational complexity. |
