Device-To-Device (D2D) Cross Link Power Control

Abstract

Device-to-device (D2D) cross link power control systems and methods may be disclosed. For example, a device such as a UE or WTRU may determine whether it may have simultaneous transmissions where at least one of the transmissions may include a cross link transmission. The device may further determine whether a total transmit power of the simultaneous transmissions may exceed a maximum transmit power of the device. If the device may have simultaneous transmissions and such transmissions may exceed the maximum transmit power, the device may reallocate power based on a priority or priority setting. The device may further determine a maximum cross link power, a maximum device power, and a cross link transmit power level such that the device may further control the power for transmissions based thereon.

1 - 25 . (canceled) 
     
     
         26 . A method of reporting power headroom using a wireless transmit/receive unit (WTRU), comprising:
 determining, by a WTRU, a maximum transmit power;   determining, by the WTRU, a current cross link power;   determining, by the WTRU, a cross link power headroom using the maximum transmit power and the current cross link power; and   reporting, by the WTRU, to a network entity, the cross link power headroom.   
     
     
         27 . A method of controlling a cross link transmit power level using a wireless transmit/receive unit (WTRU) for a direct cross link transmission with another WTRU, the method comprising:
 receiving, by the WTRU, from a network entity, information indicating a maximum cross link power level;   determining the cross link transmit power level based on the received information; and   sending the cross link transmission to the other WTRU using the determined cross link transmit power level.   
     
     
         28 . The method of  claim 27 , further comprising selecting a cross link transmit power control (TPC) formula. 
     
     
         29 . The method of  claim 28 , wherein
 the cross link TPC formula is selected from a plurality of cross link TPC formulas;   the determining of the cross link transmit power level is in accordance with at least the selected cross link TPC formula; and   the cross link transmit power level in one cross link TPC formula is determined based on a bandwidth associated with the cross link transmission and path loss information.   
     
     
         30 . The method of  claim 29 , wherein the path loss information is associated with one of: between the WTRU and a network entity or between the WTRU and the other WTRU. 
     
     
         31 . The method of  claim 27 , wherein the cross link transmit power level is controlled on a per-transmission time interval (TTI) basis. 
     
     
         32 . The method of  claim 29 , further comprising:
 receiving, by the WTRU, an explicit indication indicating one of the plurality of cross link TPC formulas in downlink control information (DCI),   wherein:
 the DCI includes a TPC command; and 
 the explicit indication is included in the TPC command. 
   
     
     
         33 . The method of  claim 27 , wherein the cross link transmit power level is determined in connection with a transmission power level of an uplink (UL) channel between the WTRU and a network entity. 
     
     
         34 . The method of  claim 32 , further comprising:
 determining a cross link power control mode for use by the WTRU, wherein the cross link power control mode is associated with the received explicit indication.   
     
     
         35 . The method of  claim 34 , wherein the cross link TPC formula is selected in accordance with the cross link power control mode. 
     
     
         36 . The method of  claim 28 , wherein the selecting of the cross link TPC formula includes selecting a first cross link TPC formula from first and second cross link TPC formulas, the first cross link TPC formula being associated with a first cross link power control mode and . the second cross link TPC formula being associated with a second cross link power control mode. 
     
     
         37 . The method of  claim 28 , further comprising receiving an indication from a network entity, wherein the cross link TPC formula is selected from a plurality of cross link TPC formulas based on at least the received indication. 
     
     
         38 . The method of  claim 28 , wherein the selected cross link TPC formula is one of: (1) calculated based on path loss information or (2) used semi-statically for more than one subframe. 
     
     
         39 . A wireless transmit/receive unit (WTRU) comprising:
 a transmitter;   a receiver configured to receive from a network entity information indicating a maximum cross link power level; and   a processor, operably coupled to the receiver and the transmitter, configured to: determine the cross link transmit power level based on the received information,   wherein the transmitter is configured to send the cross link transmission to the other WTRU using the determined cross link transmit power level.   
     
     
         40 . The WTRU of  claim 39 , wherein:
 the cross link transmit power level in a first cross link TPC formula is determined based on a bandwidth associated with the cross link transmission and path loss information; and   the path loss information relates to one of: a first path loss between the WTRU and a network entity or a second path loss between the WTRU and the other WTRU.   
     
     
         41 . The WTRU of  claim 39 , wherein the processor is configured to control the cross link transmit power level on a per-transmission time interval (TTI) basis. 
     
     
         42 . The WTRU of  claim 39 , wherein:
 the receiver is configured to receive an explicit indication indicating a cross link TPC formula in downlink control information (DCI);   the DCI includes a TPC command; and   the explicit indication is included in the TPC command.   
     
     
         43 . The WTRU of  claim 39 , wherein the processor is configured to determine the cross link transmit power level in connection with a transmission power level of an uplink (UL) channel between the WTRU and a network entity. 
     
     
         44 . The WTRU of  claim 42 , wherein:
 the processor is configured to determine a cross link power control mode for use by the WTRU; and   the cross link power control mode is associated with the explicit indication.   
     
     
         45 . The WTRU of  claim 44 , wherein the cross link TPC formula is selected in accordance with the cross link power control mode.