It is my understanding on xDSL that data is RS encoded and is applied (along with Interleaving) on the downstream, it is then received, deinterleaved, and any data that needs correcting is corrected, data that can not be corrected (CRC). is requested for a re-transmit... now in the reverse, why do we see upstream FEC errors when the data is outgoing and would only typically have errors at the receiving end?
thanks in advance