The figure below shows the ATSC-M/H frame structure for transmission of the M/H data and main data. One ATSC-M/H frame consists of 5 sub-frames. And each sub-frame shall consist of 16 consecutive M/H slots.
The M/H slot is the basic time period for multiplexing of M/H data and main data. A slot consists of 156 TS packets (before byte interleaving). A slot may consist of only main data, or may carry a group of 118 M/H-carrying MHE packets plus 38 main data.
Figure 1. ATSC-M/H frame structure
In the M/H frame structure, there are some key terms.
An M/H Ensemble is a collection of M/H services with the same quality of service and encoded with the same FEC codes.
A group is a collection of 118 consecutive MHE-encapsulated MPEG 2 TS packets transmitting the M/H service data. The groups are assigned to the slots in an M/H sub-frame according to the equation below, where i (0 ~ 15) is the group number and j (0 ~ 15) is the slot number.
j = (4i + O) mod 16, O = 0 if i < 4
O = 2 else if i < 8
O = 1 else if i < 12
O = 3 else
A parade is a collection of M/H groups contained within one M/H Frame. It carries data from one or two RS Frames depending on the RS frame mode. Each RS Frame carriers one M/H Ensemble.