Is there a way to define enumeration for certain signals after simulation?
You want a user defined radix. For example

radix define States {
11'b00000000001 "IDLE",
11'b00000000010 "CTRL",
11'b00000000100 "WT_WD_1",
11'b00000001000 "WT_WD_2",
11'b00000010000 "WT_BLK_1",
11'b00000100000 "WT_BLK_2",
11'b00001000000 "WT_BLK_3",
11'b00010000000 "WT_BLK_4",
11'b00100000000 "WT_BLK_5",
11'b01000000000 "RD_WD_1",
11'b10000000000 "RD_WD_2",
11'bzzzzzzzzzzzz "UNCONNECTED",
11'bxxxxxxxxxxx "ERROR",
-default hex
}


And then you can apply the radix States to your signal for use in the waveform or any other place you might want to examine the signal.