Change in CP config

Can eNB change the CP config (Normal vs. Extended) if the max delay spread as experienced by an UE worsens? If so, how does eNB inform UE of the change?

I think change in CP requires cell reset. If UE not support extended, it can not access the cell.
UE capability also not mention about extended support.

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The reason why 3GPP designed normal and extended CP is I think to provide cell with flexibility to switch across them when the propagation delay spread condition from UEs deteriorates. Cell sites should be able to switch across them dynamically. At the start of each cell, otherwise, how they will know if the propagation delay is within limit or exceeds threshold in order to switch to extended CP?
Cell Reset may be an option but it should be transparent to UE which I do not see to be as of now without a valid explanation.

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No, the reason of extended CP is to support large-delay cell.
extended cells have only 12 symbols of 1 slot, better coverage but lower capacity.
normal cells have 14 symbols of 1 slot, so change from NCP to EXP physical layer will be changed, and of course must reset cell, not optional.
ECP is suggested in some area such as island, sea, …
But actually I have never seen ECP sites deployed in LTE.
In 5G, some test of FWA over long distance by using mmwave extended range.

Yeah, that is what I wanted to know how in a cell NCP to ECP change is performed by eNB and how UE perceives this change.

Cells can be configured in either NCP or ECP mode, can not adaptive change between 2 mode, because it will affect all UEs in the cell, and must reconfigure/reset cell to change between 2 modes.

Okay I see. But then I do not understand why 3GPP designed and conceptualized ECP. They could have kept matters simple and just keep NCP, altogether remove ECP if benefits of ECP cannot be enjoyed by UEs in a cell in real time.

Recently, record of mmwave 6.5km 1gbps is done with ECP.
It demonstrate fwa by mmwave for rural area.
I think in mmwave ECP may be more used because mmwave coverage is so small.

@Hainm, completely second your thoughts.

Not 14 symbol per slot for normal 7 and for extend CP 6 symbol