Patent ID: 8867593

Claim:
A communication method for a digital subscriber line (DSL) system comprising a first transceiver and a second transceiver coupled to the first transceiver via a subscriber line, comprising: performing a communication between the first transceiver and the second transceiver with first bit numbers for sub-carriers, wherein the first bit numbers indicate a first bit allocation on the sub-carriers; transmitting a switch message for requesting a rate decrease from the first transceiver to the second transceiver when the first transceiver determines that an obtained communication performance parameter reaches or exceeds a predetermined value; and executing a switch to second bit numbers for the sub-carriers at a certain symbol of a frame in response to the transmission of the switch message, wherein the second bit numbers indicate a second bit allocation on the sub-carriers; wherein the first transceiver calculates the second bit numbers for the sub-carriers by subtracting a corresponding bit number from the first bit numbers for the sub-carriers; and wherein the first transceiver transmits the corresponding bit number to the second transceiver for calculating bit numbers which are as same as the second bit numbers.