"高维差分光空间调制实现高频谱效率和误码性能的折中"

High-dimensional differential optical spatial modulation (HD-DOSM) is proposed in response to the inadequate spectral efficiency in existing differential optical spatial modulation systems (DOSM). By utilizing high energy efficiency pulse position modulation (PPM) and high spectral efficiency pulse amplitude modulation (PAM), a space-time dispersion matrix satisfying the differential process is constructed, resulting in a high-dimensional DOSM scheme that encompasses spatial, temporal, and symbol domains. The principles of the HD-DOSM coding are detailed, and the theoretical upper bound of the bit error rate for HD-DOSM is derived and compared with DOSM in terms of performance. The results demonstrate a trade-off between spectral efficiency and error performance. When the spectral efficiency is 1 bit·s -1·Hz -1 and the bit error rate is 1×10 -3, compared to PAM-based DOSM, HD-DOSM achieves an improvement of approximately 2 dB in signal-to-noise ratio and an increase of 2 bpcu (bit per channel use) in transmission rate. To effectively reduce the computational complexity of the decoding algorithm at the receiver end, a step-by-step detection algorithm for PPM symbols is proposed, leveraging the sparsity of transmitted signals. When the PPM order is 4, the proposed approach achieves a reduction in complexity of approximately 75% compared to maximum likelihood detection algorithms.