载波聚合时好像有个叫TAG的东西，请问这个什么意思？

ewinda1989

如下面这段协议：

[TS 36.213, clause 5.1.1.1]

If the UE is configured with multiple TAGs, the UE shall, when requested by higher layers, to transmit PRACH in a secondary serving cell in parallel with PUSCH/PUCCH in a different serving cell belonging to a different TAG, adjust the transmission power of PUSCH/PUCCH so that its total transmission power does not exceed on the overlapped portion.

这个TAG是什么用途？它描述的是什么含义？我猜测的是和SCell有关，是每个SCell会为UE分配一个TAG吗？