IDLE MODE FOR DIGITAL SUBSCRIBER LINE

摘要

A system and method for generating and repetitively transmitting a single modulated symbol during idle periods in user data in a digital subscriber line (DSL) communication system. The spectral properties of the transmitted modulated symbol match those of user data modulated symbols. For an asynchronous DSL system, a preferred idle symbol is the "superframe" synchronization symbol. A separate modulated end-of-idle symbol is the idle symbol shifted by a 180 DEG phase shift. The transmitter in a DSL modem would calculate the idle state modulated symbol once at the start of the idle period and then simply repeat this symbol until the end of the period, in which case the transmitter would invert the final idle symbol. At the receiver (600), symbol detection (606) can be performed in the time-domain for faster and easier detection, requiring little processing power. Upon detection the end-of-idle symbol (610), the receiver exits the idle mode (614).