Method and apparatus for scheduling user equipment uplink transmissions on an unlicensed carrier

Abstract

A method and apparatus schedule user equipment uplink transmissions on an unlicensed carrier. A grant for transmitting physical uplink shared channel on a serving cell operating on an unlicensed carrier can be received in a subframe. A set of subframes can be determined for possible transmission of the physical uplink shared channel. Listen before talk can be performed on the unlicensed carrier to determine an earliest unoccupied subframe in the set of subframes. A physical uplink shared channel can be transmitted in multiple subframes within the set of subframes on the unlicensed carrier, starting with the earliest unoccupied subframe, in response to receiving the grant.

The invention claimed is: 
     
       1. A method in a user equipment, the method comprising:
 receiving, in a subframe, a grant for transmitting a physical uplink shared channel on a serving cell operating on an unlicensed carrier, where the grant includes multiple new data indicators; 
 determining a set of subframes for possible transmission of the physical uplink shared channel, where each new data indicator of the multiple new data indicators received within the grant is associated with each subframe within the determined set of subframes for possible transmission of the physical uplink shared channel; 
 performing listen before talk on the unlicensed carrier to determine an earliest unoccupied subframe in the set of subframes; and 
 transmitting the physical uplink shared channel transmissions in multiple subframes within the set of subframes on the unlicensed carrier, starting with the earliest unoccupied subframe, in response to receiving the grant, wherein either new data or a retransmission is transmitted in the physical uplink channel in each subframe of the multiple subframes according to the new data indicator. 
 
     
     
       2. The method according to  claim 1 ,
 wherein the grant for transmitting the physical uplink shared channel includes a hybrid automatic repeat request identifier, and 
 wherein the method further comprises determining a new hybrid automatic repeat request identifier for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes made in response to the grant, where the new hybrid automatic repeat request identifier is determined based on the received hybrid automatic repeat request identifier and a subframe index of each subframe of the multiple subframes, where the subframe index of each subframe of the multiple subframes is a position of each subframe within the set of subframes. 
 
     
     
       3. The method according to  claim 2 , wherein determining the new hybrid automatic repeat request identifier further comprises determining the new hybrid automatic repeat request identifier for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes made in response to the first grant, where the new hybrid automatic repeat request identifier is determined using a formula x″=MOD (x+m, M_UL_HARQ), where x″ is the new hybrid automatic repeat request identifier, where x is the hybrid automatic repeat request identifier in the grant, where m is the position of each subframe within the set of subframes, and where M_UL_HARQ is the maximum number of uplink HARQ processes. 
     
     
       4. The method according to  claim 2 , wherein different new hybrid automatic repeat request identifier values are used for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes. 
     
     
       5. The method according to  claim 1 ,
 wherein the grant includes an indication of the set of subframes for possible transmission of physical uplink shared channel, and 
 wherein the method further comprises determining the set of subframes for possible transmission of the physical uplink shared channel based on the received indication of the set of subframes in the grant. 
 
     
     
       6. The method according to  claim 1 , further comprising:
 receiving a configuration indicating the maximum number of contiguous subframes for possible transmission of the physical uplink shared channel from a higher layer, where the higher layer is higher than a physical layer; and 
 wherein determining the set of subframes further comprises determining the set of subframes for possible transmission of the physical uplink shared channel based on the received configuration. 
 
     
     
       7. The method according to  claim 1 , further comprising receiving signaling indicating a minimum time duration to perform listen before talk,
 wherein performing listen before talk comprises performing listen before talk on the unlicensed carrier before transmitting the physical uplink shared channel, where performing listen before talk is based on the received signaling of the minimum time duration to perform listen before talk. 
 
     
     
       8. The method according to  claim 1 ,
 wherein the grant includes an indication of a starting symbol of the physical uplink shared channel transmissions, the starting symbol being one selected from a first symbol and a second symbol of the subframe, and 
 wherein transmitting the physical uplink channel transmissions comprises transmitting the physical uplink shared channel transmissions starting with the earliest unoccupied subframe and the indicated starting symbol. 
 
     
     
       9. The method according to  claim 1 , further comprising transmitting the physical uplink shared channel transmissions in multiple subframes excluding a last symbol of the subframe. 
     
     
       10. An apparatus comprising:
 a transceiver that receives, in a subframe, a grant for transmitting physical uplink shared channel on a serving cell operating on an unlicensed spectrum, where the grant includes multiple new data indicators; and 
 a controller that determines a set of subframes for possible transmission of the physical uplink shared channel, and performs listen before talk on the unlicensed carrier to determine an earliest unoccupied subframe in the set of subframes, where each new data indicator of the multiple new data indicators received within the grant is associated with each subframe within the determined set of subframes for possible transmission of the physical uplink shared channel, 
 wherein the transceiver transmits the physical uplink shared channel transmissions in multiple subframes within the set of subframes on the unlicensed carrier, starting with the earliest unoccupied subframe, in response to receiving the grant, wherein either new data or a retransmission is transmitted in the physical uplink channel in each subframe of the multiple subframes according to the new data indicator. 
 
     
     
       11. The apparatus according to  claim 10 ,
 wherein the grant for transmitting physical uplink shared channel includes a hybrid automatic repeat request identifier, and 
 wherein the controller determines a new hybrid automatic repeat request identifier for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes made in response to the grant, where the new hybrid automatic repeat request identifier is determined based on the received hybrid automatic repeat request identifier and a subframe index of each subframe of the multiple subframes, where the subframe index of each subframe of the multiple subframes is a position of each subframe within the set of subframes. 
 
     
     
       12. The apparatus according to  claim 11 , wherein the controller determines the new hybrid automatic repeat request identifier for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes made in response to the first grant, where the new hybrid automatic repeat request identifier is determined using a formula x″=MOD (x+m, M_UL_HARQ), where x″ is the new hybrid automatic repeat request identifier, where x is the hybrid automatic repeat request identifier in the grant, where m is the position of each subframe within the set of subframes, and where M_UL_HARQ is the maximum number of uplink HARQ processes. 
     
     
       13. The apparatus according to  claim 11 , wherein different new hybrid automatic repeat request identifier values are used for each physical uplink shared channel transmission of the physical uplink shared channel transmissions in the multiple subframes. 
     
     
       14. The apparatus according to  claim 10 ,
 wherein the grant includes an indication of the set of subframes for possible transmission of physical uplink shared channel, and 
 wherein the controller determines the set of subframes for possible transmission of the physical uplink shared channel based on the received indication of the set of subframes in the grant. 
 
     
     
       15. The apparatus according to  claim 10 ,
 wherein the transceiver receives a configuration indicating the maximum number of contiguous subframes for possible transmission of the physical uplink shared channel from a higher layer, where the higher layer is higher than a physical layer, and 
 wherein the controller determines the set of subframes for possible transmission of the physical uplink shared channel based on the received configuration. 
 
     
     
       16. The apparatus according to  claim 10 ,
 wherein the transceiver receives signaling indicating a minimum time duration to perform listen before talk, and 
 wherein the controller performs listen before talk on the unlicensed carrier before initiating the physical uplink shared channel transmission, where performing listen before talk is based on the received signaling of the minimum time duration to perform listen before talk. 
 
     
     
       17. The apparatus according to  claim 10 ,
 wherein the grant includes an indication of a starting symbol of the physical uplink shared channel transmissions, the starting symbol being one selected from a first symbol and a second symbol of the subframe, and 
 wherein the transceiver transmits the physical uplink shared channel transmissions starting with the earliest unoccupied subframe and the indicated starting symbol. 
 
     
     
       18. The apparatus according to  claim 10 , wherein the transceiver transmits the physical uplink shared channel transmissions in multiple subframes excluding a last symbol of the subframe. 
     
     
       19. A method performed by a user equipment (UE), the method comprising:
 determining a set of subframes for possible transmission of a physical uplink shared channel (PUSCH) on a serving cell operating on an unlicensed carrier;   performing listen before talk on the unlicensed carrier to determine an earliest unoccupied subframe in the set of subframes;   transmitting PUSCH transmissions in multiple subframes within the set of subframes on the unlicensed carrier, starting with the earliest unoccupied subframe;   determining a hybrid automatic repeat request (HARQ) identifier for each PUSCH transmission of the PUSCH transmissions in the multiple subframes; and   transmitting each determined HARQ identifier along with each PUSCH transmission,   where the set of subframes for possible transmission of the PUSCH on a serving cell operating on an unlicensed carrier is determined based on a grant received at the UE or configured via higher layers.    
     
     
       20. The method according to claim 19, further comprising determining the HARQ identifier for each PUSCH transmission of the PUSCH transmissions in the multiple subframes based on an order of the PUSCH transmission within the PUSCH transmission in the multiple subframes.  
     
     
       21. The method according to claim 19, further comprising determining the HARQ identifier for each PUSCH transmission of the PUSCH transmissions in the multiple subframes based on a subframe index of each subframe of the multiple subframes, where the subframe index of each subframe of the multiple subframes is a position of each subframe within the set of subframes.  
     
     
       22. The method according to claim 19, wherein different new HARQ identifier values are used for each PUSCH transmission.  
     
     
       23. The method according to claim 19, further comprising:
 receiving a grant requesting a retransmission, where the grant includes a HARQ identifier that was previously transmitted by the UE; and   transmitting PUSCH in response to the grant to retransmit data that is associated with the same HARQ identifier that was previously transmitted by the UE.    
     
     
       24. The method according to claim 19, further comprising:
 determining a demodulation reference signal cyclic shift value based on the HARQ identifier for each PUSCH transmission; and   transmitting a demodulation reference signal using the determined cyclic shift value for each PUSCH transmission, along with each PUSCH transmission of the PUSCH transmissions in the multiple subframes.    
     
     
       25. The method according to claim 19, further comprising multiplexing bits indicating the each determined HARQ identifier into a portion of resources assigned for each PUSCH transmission of the PUSCH transmissions in the multiple subframes.  
     
     
       26. The method according to claim 25, further comprising:
 encoding the each determined HARQ identifier and a cyclic redundancy check using a code to generate the bits; and   multiplexing the bits into a portion of resources assigned for each PUSCH transmission of the PUSCH transmissions in the multiple subframes.    
     
     
       27. The method according to claim 25, further comprising:
 mapping the bits indicating the each determined HARQ identifier to a subset of modulation symbols comprising the portion of resources of a set of modulation symbols assigned for each PUSCH transmission PUSCH transmission; and   mapping encoded uplink shared channel data to a remaining subset of the set of modulation symbols excluding the subset of modulation symbols used for mapping the bits.    
     
     
       28. The method according to claim 27, wherein the subset of the modulation symbols used for mapping the bits occupy a portion of symbols in the subframe.  
     
     
       29. The method according to claim 27, further comprising determining a number of resource elements for the subset of the modulation symbols based on a modulation coding scheme of the each PUSCH transmission of the PUSCH transmissions in the multiple subframes.  
     
     
       30. The method according to claim 19, further comprising:
 determining a new data indicator for each PUSCH transmission of the PUSCH transmissions in the multiple subframes, and   transmitting either new data or retransmission in each subframe according to the new data indicator.    
     
     
       31. The method according to claim 19, further comprising:
 receiving a configuration indicating the maximum number of contiguous subframes for possible transmission of the PUSCH from a higher layer, where the higher layer is higher than a physical layer, and   determining the set of subframes for possible transmission of the PUSCH based on the received configuration.    
     
     
       32. The method according to claim 19, further comprising:
 receiving signaling indicating a minimum time duration to perform listen before talk; and   performing listen before talk on the unlicensed carrier before initiating a PUSCH transmission based on the received signaling of the minimum time duration to perform listen before talk.    
     
     
       33. An apparatus comprising:
 a controller that
 determines a set of subframes for possible transmission of a physical uplink shared channel (PUSCH) on a serving cell operating on an unlicensed carrier, and 
 performs listen before talk on the unlicensed carrier to determine an earliest unoccupied subframe in the set of subframes, and 
   a transceiver coupled to the controller, where the transceiver transmits PUSCH transmissions in multiple subframes within the set of subframes on the unlicensed carrier, starting with the earliest unoccupied subframe,   wherein the controller determines a hybrid automatic repeat request (HARQ) identifier for each PUSCH transmission of the PUSCH transmissions in the multiple subframes, and   wherein the transceiver transmits each determined HARQ identifier along with each PUSCH transmission,   wherein the set of subframes for possible transmission of the PUSCH on a serving cell operating on an unlicensed carrier is determined based on a grant received at the apparatus or configured via higher layers.