Abis ts for data is not fixed, it can vary as per vendor specs or to increase throughput.
there is no one to one correlation b/w PDTCH on Um n Abis ts for data on Abis E1.
(correct me if im wrong)
one doubt in ur explanation as im not familiar with these terms.
1 Abis TS = 1 Abis nibble??
wat i understood is,
1 Abis TS is 64kbps ts on Abis E1
1 Abis nibble is 16kbps ts i.e 1/4 of 1 Abis TS.