Method and apparatus for providing power saving of monitoring for device-to-device communication in a wireless communication system

Abstract

A method and apparatus are disclosed from the perspective of a second User Equipment (UE) for performing sidelink communication. In one embodiment, the method includes the second UE being (pre-)configured with a sidelink resource pool in a carrier or cell, wherein a DRX (Discontinuous Reception) pattern is associated to the sidelink resource pool. The method also includes the second UE selecting a resource in the sidelink resource pool based on the DRX pattern, wherein a specific message becomes available for transmission in the second UE. The method further includes the second UE transmitting the specific message on the resource to a plurality of UEs comprising at least a first UE.

What is claimed is: 
     
         1 . A method of a first User Equipment (UE) for performing sidelink communication, comprising:
 being (pre-)configured with a sidelink resource pool in a carrier or cell;   transmitting a sidelink transmission to a second UE for requesting a second Discontinuous Reception (DRX) pattern, wherein the sidelink transmission includes information of a first DRX pattern;   receiving a message from the second UE, wherein the message includes information of the second DRX pattern; and   monitoring sidelink control information in the sidelink resource pool based on the second DRX pattern.   
     
     
         2 . The method of  claim 1 , wherein the information of the first DRX pattern indicates an active duration or a sleep duration for a cycle, or wherein the active duration is followed by the sleep duration in the cycle, or wherein the active duration is prior to the sleep duration in the cycle. 
     
     
         3 . The method of  claim 1 , wherein the first UE receives the message on a resource in active duration of the first DRX pattern, or wherein the message is a dedicated or unicast message to the first UE. 
     
     
         4 . The method of  claim 1 , wherein the first UE applies the second DRX pattern for a cycle repeatedly. 
     
     
         5 . The method of  claim 1 , wherein the information of the second DRX pattern indicates an active duration or a sleep duration for a cycle, or wherein the active duration is followed by the sleep duration in the cycle, or wherein the active duration is prior to the sleep duration in the cycle. 
     
     
         6 . The method of  claim 1 , wherein the first UE is configured with power saving. 
     
     
         7 . The method of  claim 5 , wherein the first UE monitors sidelink control information based on the second DRX pattern, and wherein the first UE monitors sidelink control information in the active duration for each cycle, and/or does not monitor sidelink control information in the sleep duration for each cycle. 
     
     
         8 . The method of  claim 1 , wherein the first UE establishes a unicast sidelink connection or a groupcast sidelink connection with the second UE, or wherein the sidelink transmission is a unicast transmission or a groupcast transmission. 
     
     
         9 . The method of  claim 1 , wherein the information of the first DRX pattern is associated with the first UE, and/or wherein the information of the first DRX pattern is determined by the first UE. 
     
     
         10 . A method of a second User Equipment (UE) for performing sidelink communication, comprising:
 being (pre-)configured with a sidelink resource pool in a carrier or cell;   receiving a sidelink transmission from a first UE for requesting a second Discontinuous Reception (DRX) pattern, wherein the sidelink transmission includes information of a first DRX pattern; and   transmitting a message to the first UE, wherein the message includes information of the second DRX pattern for configuring or indicating the first UE to monitor sidelink control information in the sidelink resource pool based on the second DRX pattern.   
     
     
         11 . The method of  claim 10 , wherein the information of the first DRX pattern indicates an active duration or a sleep duration for a cycle, or wherein the active duration is followed by the sleep duration in the cycle, or wherein the active duration is prior to the sleep duration in the cycle. 
     
     
         12 . The method of  claim 10 , wherein the second UE transmits the message on a resource in active duration of the first DRX pattern, or wherein the message is a dedicated or unicast message to the first UE. 
     
     
         13 . The method of  claim 10 , wherein the information of the second DRX pattern indicates an active duration or a sleep duration for a cycle, or wherein the active duration is followed by the sleep duration in the cycle, or wherein the active duration is prior to the sleep duration in the cycle. 
     
     
         14 . The method of  claim 10 , wherein the second UE establishes a unicast sidelink connection or a groupcast sidelink connection with the first UE, or wherein the sidelink transmission is a unicast transmission or a groupcast transmission. 
     
     
         15 . The method of  claim 10 , wherein the second UE transmits the message to the first UE in response to the information of the first DRX pattern or the sidelink transmission from the first UE. 
     
     
         16 . A first User Equipment (UE) for performing sidelink communication, comprising:
 a memory; and   a processor operatively coupled to the memory, wherein the processor is configured to execute program code to:
 be (pre-)configured with a sidelink resource pool in a carrier or cell; 
 transmit a sidelink transmission to a second UE for requesting a second Discontinuous Reception (DRX) pattern, wherein the sidelink transmission includes information of a first DRX pattern; 
 receive a message from the second UE, wherein the message includes information of the second DRX pattern; and 
 monitor sidelink control information in the sidelink resource pool based on the second DRX pattern. 
   
     
     
         17 . The first UE of  claim 16 , wherein the information of the first DRX pattern indicates an active duration or a sleep duration for a cycle, or wherein the active duration is followed by the sleep duration in the cycle, or wherein the active duration is prior to the sleep duration in the cycle. 
     
     
         18 . The first UE of  claim 16 , wherein the first UE receives the message on a resource in active duration of the first DRX pattern, or wherein the message is a dedicated or unicast message to the first UE. 
     
     
         19 . The first UE of  claim 16 , wherein:
 the first UE applies the second DRX pattern for a cycle repeatedly; or   the information of the second DRX pattern indicates an active duration or a sleep duration for the cycle, or the active duration is followed by the sleep duration in the cycle, or the active duration is prior to the sleep duration in the cycle; or   the first UE is configured with power saving; or   the first UE monitors sidelink control information based on the second DRX pattern, wherein the first UE monitors sidelink control information in the active duration for each cycle, and/or does not monitor sidelink control information in the sleep duration for each cycle.   
     
     
         20 . The first UE of  claim 16 , wherein the information of the first DRX pattern is associated with the first UE, and/or wherein the information of the first DRX pattern is determined by the first UE.