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UBC Theses and Dissertations

Is spiral modulation really useful? Chu, Haobing


The performance analysis of modulation techniques has been studied extensively. In this thesis, we investigate the performance of a new modulation technique called spiral modulation. Spiral modulation uses complex spirals in the complex plane to modulate data and form complex signals. Spiral modulation was proposed by Astrapi Corporation and the company claimed that spiral modulation is better than the conventional modulations and can exceed the Shannon limit. In this thesis, we explore the potential of spiral modulation and verify the claims by using MATLAB simulation according to the Astrapi's spiral modulation patents. We first present the system structure and the concept of spiral modulation. Then, we focus on the bit-error rate (BER) performance analysis and the spectral efficiency analysis by using MATLAB simulation. In the BER performance analysis, our simulation results reveal that the BER performance of spiral modulation can be better than some conventional modulations when the constellation size is equal or larger than eight if the bandwidth is not taken into consideration. In the spectral efficiency analysis, we estimate the bandwidth of spiral modulation signals by using the periodogram method. The results show that the bandwidth of spiral modulation signal is not strictly limited. A spectral efficiency plane is plotted, and it shows that the spectral efficiency of spiral modulation is worse than the conventional modulation techniques. We conclude that, contrary to the claim made by Astrapi, the spiral modulation can not exceed Shannon capacity boundary on the spectral efficiency plane.

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Attribution-NonCommercial-NoDerivatives 4.0 International