Method for transmitting/receiving d2d signal in wireless communication system and apparatus therefor

Abstract

A method of receiving a D2D discovery signal by UE with one or more RX chains on FDD carriers in a wireless communication system, and which receiving, from an eNodeB, information for configuring a gap for the D2D signal and securing a time required for a frequency band switching operation of the one or more RX chains which are less than a number of RX chains necessary to perform simultaneous reception of downlink signal and the D2D signal. Further, the UE does not receive the downlink signal in the gap during reception of the D2D signal or reception of a D2D synchronization signal related to reception of the D2D signal, and the UE does not count a specific timer related to DRX operation of the downlink signal.

What is claimed is: 
     
         1 . A method of receiving a device-to-device (D2D) discovery signal by a user equipment (UE) with one or more RX chains on Frequency Division Duplex (FDD) carriers in a wireless communication system, the method comprising:
 receiving, from an eNodeB, information for configuring a gap for the D2D signal and securing a time required for a frequency band switching operation of the one or more RX chains which are less than a number of RX chains necessary to perform simultaneous reception of downlink signal and the D2D signal,   wherein the UE does not receive the downlink signal in the gap during reception of the D2D signal or reception of a D2D synchronization signal related to reception of the D2D signal, and   wherein the UE does not count a specific timer related to DRX operation of the downlink signal.   
     
     
         2 . The method according to  claim 1 , wherein the time required for frequency band switching operation comprises at least one of a first interruption time caused by switching the one or more Rx chains from a carrier for the downlink signal to a carrier for the D2D signal, a tuning time for tuning the one or more Rx chains on the carrier for the D2D signal, and a second interruption time caused by switching the one or more Rx chains from the carrier for the D2D signal to the carrier for the downlink signal. 
     
     
         3 . The method according to  claim 1 , wherein the specific timer comprises at least one of an onDurationTimer, a drx-inactivityTimer and a drx-RetransmissionTimer. 
     
     
         4 . The method according to  claim 1 , wherein the gap is defined in the form of a bitmap indicating a position of one or more subframes used as the gap. 
     
     
         5 . The method according to  claim 1 , wherein the gap is configured on subframes belonging to a D2D discovery resource pool indicating discovery subframes as well as two or more subframes preceding and following the subframes belonging the D2D discovery resource pool, and
 wherein the two or more subframes preceding and following the subframes are determined based on synchronization error information related to a neighbor-cell.   
     
     
         6 . The method according to  claim 1 , further comprising:
 prioritizing, by the UE, reception of the D2D signal over the downlink signal based on the D2D signal being overlapped with a downlink signal on a downlink subframe and the downlink subframe being configured as the gap; and   prioritizing, by the UE, reception of the downlink signal over the D2D signal based on the D2D signal being overlapped with the downlink signal on the downlink subframe and the downlink subframe not being configured as the gap.   
     
     
         7 . The method according to  claim 1 , wherein the D2D signal is a discovery signal, a D2D Synchronization Signal (D2DSS), a D2D data signal, or a scheduling assignment signal. 
     
     
         8 . The method according to  claim 1 , wherein the gap is configured to the at least one downlink subframe overlapping a D2D signal resource pool for receiving the D2D signal. 
     
     
         9 . A User Equipment (UE) with one or more RX chains, configured for receiving a device-to-device (D2D) signal on Frequency Division Duplex (FDD) carriers in a wireless communication system, the UE comprising:
 a transceiver; and   a processor coupled to the transceiver,   wherein the processor is configured to receive, from an eNodeB, information for configuring a gap for the D2D signal and securing a time necessary for a frequency band switching operation of the one or more RX chains which are less than a number of RX chains necessary to perform simultaneous reception of downlink signal and the D2D discovery signal,   wherein the processor does not receive the downlink signal in the gap during reception of the D2D signal or a D2D synchronization signal related to reception of the D2D signal, and   wherein the processor does not count a specific timer related to DRX operation of the downlink signal.   
     
     
         10 . The UE according to  claim 9 , wherein the time required for frequency band switching operation comprises at least one of a first interruption time caused by switching the one or more Rx chains from a carrier for the downlink signal to a carrier for the D2D signal, a tuning time for tuning the one or more Rx chains on the carrier for the D2D signal, and a second interruption time caused by switching the one or more Rx chains from the carrier for the D2D signal to the carrier for the downlink signal 
     
     
         11 . The UE according to  claim 9 , wherein the specific timer comprises at least one of an onDurationTimer, a drx-inactivityTimer and a drx-RetransmissionTimer. 
     
     
         12 . The UE according to  claim 9 , wherein the gap is defined in the form of a bitmap indicating a position of one or more subframes used as the gap. 
     
     
         13 . The UE according to  claim 9 , wherein the gap is configured on subframes belonging to a D2D discovery resource pool indicating discovery subframes as well as two or more subframes preceding and following the subframes belonging the D2D discovery resource pool, and
 wherein the two or more subframes preceding and following the subframes are determined based on synchronization error information related to neighbor-cell.   
     
     
         14 . The UE according to  claim 9 , wherein the processor is further configured to:
 prioritize reception of the D2D signal over the downlink signal based on the D2D signal being overlapped with a downlink signal on a downlink subframe and the downlink subframe being configured as the gap; and   prioritize reception of the downlink signal over the D2D signal based on the D2D signal being overlapped with the downlink signal on the downlink subframe and the downlink subframe not being configured as the gap.   
     
     
         15 . The UE according to  claim 9 , wherein the D2D signal is a discovery signal, a D2D Synchronization Signal (D2DSS), a D2D data signal, or a scheduling assignment signal. 
     
     
         16 . The UE according to  claim 9 , wherein the gap is configured to the at least one downlink subframe overlapping a D2D signal resource pool for receiving the D2D signal.