In this paper, we propose symmetrical optical pulse position orthogonal space-time block code (SOPP-OSTBC) applied to m-ary pulse positions modulation (m-PPM) without the use of a complex decoding scheme for multi-output (MIMO) based ultraviolet communication (UVC) system. Experiments are conducted with various key parameters and the system performances with ON-OFF keying (OOK) modulation and .binary pulse position modulation (2-PPM) are compared. The results are useful for improving the flexibi
