This signal is termed low power idle (LPI) [13]. Low Power Idle (LPI) mode is an optional mode intended to save power that may be enabled during periods of low link utilization in which either side of a link may disable portions of device or system functionality.
intended
The transmitter sends LPI in place of idle to indicate that the link can go to sleep. After sending LPI for a period (Ts = time to sleep), the transmitter can stop signaling altogether so that the link becomes quiescent. Periodically, the transmitter sends some signals so that the link does not remain quiescent for too long without a refresh. Finally, when the transmitter wishes to resume the fully functional link, it sends normal idle signals. After a pre-determined time (Tw = time to wake) the link is active and data can be sent [13].