Listen before talk procedure in a wireless device and wireless network

Abstract

A wireless device receives an uplink grant for a licensed assisted access (LAA) cell. The uplink grant comprises a physical uplink shared channel (PUSCH) starting position field and a listen-before-talk (LBT) type field. The PUSCH starting position field indicates a PUSCH starting position in a subframe of the LAA cell. The LBT type field indicates at least one of a first LBT type or a second LBT type for the subframe. A determination is made based, at least, on uplink transmissions by the wireless device in a preceding adjacent subframe of the LAA cell, to: perform an LBT procedure for transmission of uplink signals in the subframe, or transmit the uplink signals without performing the LBT procedure for the subframe, regardless of the LBT type field indicating the first LBT type or the second LBT type. The uplink signals in the subframe may be transmitted via the LAA cell.

1 . A method, comprising:
 receiving, by a wireless device, a first uplink grant for a licensed assisted access cell, wherein the first uplink grant comprises:
 a physical uplink shared channel starting position field indicating a starting position of a physical uplink shared channel in a subframe of the licensed assisted access cell; and 
 a channel access type field indicating at least one of a first channel access type and a second channel access type for the subframe; and 
   transmitting, via the licensed assisted access cell, an uplink signal in the subframe without performing a channel access procedure regardless of the channel access type field indicating the first channel access type or the second channel access type,   wherein the channel access procedure is determined to be not being performed at least when there is an uplink transmission by the wireless device in a preceding adjacent subframe of the licensed assisted access cell.   
     
     
         2 . The method of  claim 1 , wherein:
 the first channel access type is a Category 4 listen-before-talk; and   the second channel access type is a Category 2 listen-before-talk.   
     
     
         3 . The method of  claim 1 , wherein the channel access procedure is determined to be not being performed further when there is no transmission gap between the uplink transmission by the wireless device in the preceding adjacent subframe and a transmission for the uplink signal in the subframe. 
     
     
         4 . The method of  claim 1 , wherein the channel access procedure is determined to be not being performed further when there is an uplink transmission by the wireless device in a last symbol of the preceding adjacent subframe. 
     
     
         5 . The method of  claim 1 , wherein the first uplink grant is a single-subframe uplink grant. 
     
     
         6 . The method of  claim 1 , wherein the starting position of a physical uplink shared channel comprises:
 symbol  0 ;   25 μs in symbol  0 ;   (25+TA) μs in symbol  0 ; or   symbol  1 .   
     
     
         7 . The method of  claim 6 , wherein the channel access procedure is determined to be not being performed further when the physical uplink shared channel starting position field indicates that physical uplink shared channel transmission in the subframe starts from a beginning of the symbol  0 . 
     
     
         8 . The method of  claim 1 , further comprising:
 receiving a second uplink grant for the preceding adjacent subframe.   
     
     
         9 . The method of  claim 8 , wherein the second uplink grant comprises a single-subframe uplink grant or a multi-subframe uplink grant. 
     
     
         10 . A wireless device, comprising:
 one or more processors; and   a non-transitory computer-readable storage medium for storing instructions that, when executed by the one or more processors, cause the wireless device to:
 receive a first uplink grant for a licensed assisted access cell, wherein the first uplink grant comprises:
 a physical uplink shared channel starting position field indicating a starting position of a physical uplink shared channel in a subframe of the licensed assisted access cell; and 
 a channel access type field indicating at least one of a first channel access type and a second channel access type for the subframe; and 
 
 transmit, via the licensed assisted access cell, an uplink signal in the subframe without performing a channel access procedure regardless of the channel access type field indicating the first channel access type or the second channel access type; 
 wherein the channel access procedure is determined to be not being performed at least when there is an uplink transmission by the wireless device in a preceding adjacent subframe of the licensed assisted access cell. 
   
     
     
         11 . The wireless device of  claim 10 , wherein:
 the first channel access type is a Category 4 listen-before-talk; and   the second channel access type is a Category 2 listen-before-talk.   
     
     
         12 . The wireless device of  claim 10 , wherein the channel access procedure is determined to be not being performed further when there is no transmission gap between the uplink transmission by the wireless device in the preceding adjacent subframe and a transmission for the uplink signal in the subframe. 
     
     
         13 . The wireless device of  claim 10 , wherein the channel access procedure is determined to be not being performed further when there is an uplink transmission by the wireless device in a last symbol of the preceding adjacent subframe. 
     
     
         14 . The wireless device of  claim 10 , wherein the first uplink grant is a single-subframe uplink grant. 
     
     
         15 . The wireless device of  claim 10 , wherein the starting position of a physical uplink shared channel comprises:
 symbol  0 ;   25 μs in symbol  0 ;   (25+TA) μs in symbol  0 ; or   symbol  1 .   
     
     
         16 . The wireless device of  claim 15 , wherein the channel access procedure is determined to be not being performed further when the physical uplink shared channel starting position field indicates that physical uplink shared channel transmission in the subframe starts from a beginning of the symbol  0 . 
     
     
         17 . The wireless device of  claim 10 , wherein the instructions further cause the wireless device to receive a second uplink grant for the preceding adjacent subframe. 
     
     
         18 . The wireless device of  claim 17 , wherein the second uplink grant comprises a single-subframe uplink grant or a multi-subframe uplink grant. 
     
     
         19 . A method, comprising:
 transmitting, by a base station, a first uplink grant for a licensed assisted access cell to a wireless device, wherein the first uplink grant comprises:
 a physical uplink shared channel starting position field indicating a starting position of a physical uplink shared channel in a subframe of the licensed assisted access cell; and 
 a channel access type field indicating at least one of a first channel access type and a second channel access type for the subframe; and 
   receiving, via the licensed assisted access cell, an uplink signal in the subframe from the wireless device, wherein the wireless device does not perform a channel access procedure regardless of the channel access type field indicating the first channel access type or the second channel access type;   wherein the channel access procedure is determined to be not being performed at least when there is an uplink transmission by the wireless device in a preceding adjacent subframe of the licensed assisted access cell.   
     
     
         20 . The method of  claim 19 , wherein:
 the first channel access type is a Category 4 listen-before-talk; and   the second channel access type is a Category 2 listen-before-talk.   
     
     
         21 . The method of  claim 19 , wherein the channel access procedure is determined to be not being performed further when there is no transmission gap between the uplink transmission by the wireless device in the preceding adjacent subframe and a transmission for the uplink signal in the subframe. 
     
     
         22 . The method of  claim 19 , wherein the channel access procedure is determined to be not being performed further when there is an uplink transmission by the wireless device in a last symbol of the preceding adjacent subframe. 
     
     
         23 . The method of  claim 19 , wherein the first uplink grant is a single-subframe uplink grant. 
     
     
         24 . The method of  claim 19 , wherein the starting position of a physical uplink shared channel comprises:
 symbol  0 ;   25 μs in symbol  0 ;   (25+TA) μs in symbol  0 ; or   symbol  1 .   
     
     
         25 . The method of  claim 24 , wherein the channel access procedure is determined to be not being performed further when the physical uplink shared channel starting position field indicates that physical uplink shared channel transmission in the subframe starts from a beginning of the symbol  0 . 
     
     
         26 . The method of  claim 19 , further comprising transmitting a second uplink grant for the preceding adjacent subframe. 
     
     
         27 . The method of  claim 26 , wherein the second uplink grant comprises a single-subframe uplink grant or a multi-subframe uplink grant. 
     
     
         28 . A base station, comprising:
 one or more processors; and   a non-transitory computer-readable storage medium for storing instructions that, when executed by the one or more processors, cause the base station to:   transmit a first uplink grant for a licensed assisted access cell to a wireless device, wherein the first uplink grant comprises:
 a physical uplink shared channel starting position field indicating a starting position of a physical uplink shared channel in a subframe of the licensed assisted access cell; and 
 a channel access type field indicating at least one of a first channel access type 
   and a second channel access type for the subframe; and   receive, via the licensed assisted access cell, an uplink signal in the subframe from the wireless device, wherein the wireless device does not perform a channel access procedure regardless of the channel access type field indicating the first channel access type or the second channel access type;   wherein the channel access procedure is determined to be not being performed at least when there is an uplink transmission by the wireless device in a preceding adjacent subframe of the licensed assisted access cell.   
     
     
         29 . The base station of  claim 28 , wherein:
 the first channel access type is a Category 4 listen-before-talk; and   the second channel access type is a Category 2 listen-before-talk.   
     
     
         30 . The base station of  claim 28 , wherein the channel access procedure is determined to be not being performed further when there is no transmission gap between the uplink transmission by the wireless device in the preceding adjacent subframe and a transmission for the uplink signal in the subframe. 
     
     
         31 . The base station of  claim 28 , wherein the channel access procedure is determined to be not being performed further when there is an uplink transmission by the wireless device in a last symbol of the preceding adjacent subframe. 
     
     
         32 . The base station of  claim 28 , wherein the first uplink grant is a single-subframe uplink grant. 
     
     
         33 . The base station of  claim 28 , wherein the starting position of a physical uplink shared channel comprises:
 symbol  0 ;   25 μs in symbol  0 ;   (25+TA) μs in symbol  0 ; or   symbol  1 .   
     
     
         34 . The base station of  claim 33 , wherein the channel access procedure is determined to be not being performed further when the physical uplink shared channel starting position field indicates that physical uplink shared channel transmission in the subframe starts from a beginning of the symbol  0 . 
     
     
         35 . The base station of  claim 28 , wherein the instructions further cause the base station to transmit a second uplink grant for the preceding adjacent subframe. 
     
     
         36 . The base station of  claim 28 , wherein a second uplink grant comprises a single-subframe uplink grant or a multi-subframe uplink grant.