Editing Orthogonal frequency-division multiplexing (section)

====BST-OFDM used in ISDB====
The ''band-segmented transmission orthogonal frequency-division multiplexing'' (''BST-OFDM'') system proposed for Japan (in the [[ISDB-T]], [[ISDB-TSB]], and [[ISDB-C]] broadcasting systems) improves upon COFDM by exploiting the fact that some OFDM carriers may be modulated differently from others within the same multiplex. Some forms of COFDM already offer this kind of [[hierarchical modulation]], though BST-OFDM is intended to make it more flexible. The 6&nbsp;MHz television channel may therefore be "segmented", with different segments being modulated differently and used for different services.

It is possible, for example, to send an audio service on a segment that includes a segment composed of a number of carriers, a data service on another segment and a television service on yet another segment—all within the same 6&nbsp;MHz television channel. Furthermore, these may be modulated with different parameters so that, for example, the audio and data services could be optimized for mobile reception, while the television service is optimized for stationary reception in a high-multipath environment.