Abstract: Efficient implementation techniques of a low power mode, (i.e. L2 mode for ADSL2) for DSL transceivers are described. The techniques save memory space and reduce implementation complexity. A constellation mapper in a DSL transmitter determines the number of bits to be retrieved for an ith sub-carrier in the low power mode based on the number of bits allocated for this same sub-carrier in a normal transmission mode, (e.g. L0 mode in ADSL2) and a bit allocation threshold T. A constellation demapper in a DSL receiver determines the number of bits used for an ith sub-carrier in the low power mode based on the bit tables for the L0 mode and the bit threshold T.

Abstract: A multi-port DSL system terminates a plurality of DSL channels that are multiplexed through a data path of a DSL transceiver. In one embodiment, data path events are generated based on the data transmission in each of the channels. When the data path becomes available to process a next data symbol, the data path processes a data symbol for the channel indicated by the data path events. Optionally, the data path may process a data symbol for a particular channel only if a predetermined amount of time has elapsed since a data symbol was processed for that data channel.