Multiple transmission time interval coordination with time division duplexing

Abstract

Methods, systems, and devices for wireless communication are described. Data may be received during transmission time intervals (TTIs) that have a short duration relative to other TTIs. The short-duration TTIs may occur within or overlap a longer duration TTI, such as a subframe. Feedback responsive to the data may be generated and assigned for transmission during an uplink TTI according to a feedback timing or delay, which may be selected to reduce latency or balance the payload size of uplink messages sent during the assigned uplink TTI. Data and feedback assignments in short-duration TTIs may be configured based on a time division duplexing (TDD) configuration for some TTIs (e.g., subframes). TTIs that are a Long Term Evolution (LTE) subframe, an LTE slot, and a duration of two LTE symbol periods may be supported. Portions of special TTIs may be used for transmissions according to shorter-duration TTIs.

What is claimed is: 
     
         1 . A method for wireless communication at a network device, comprising:
 sending signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   receiving an uplink acknowledgement message from a user equipment (UE), responsive to a downlink message, during the second TTI.   
     
     
         2 . The method of  claim 1 , further comprising:
 determining a guard period during the first TTI of the first duration in the first component carrier;   determining an additional TTI of the second duration during the guard period; and   receiving an additional uplink message during the additional TTI of the second duration.   
     
     
         3 . The method of  claim 1 , further comprising:
 receiving the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         4 . The method of  claim 1 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         5 . The method of  claim 1 , further comprising:
 receiving a SRS, from a second UE different from the UE, on the SRS portion of the plurality of uplink symbols in the first TTI.   
     
     
         6 . The method of  claim 1 , wherein the first TTI comprises one or more slots, each slot comprising two or more symbols of the plurality of uplink symbols. 
     
     
         7 . The method of  claim 1 , wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of the UE, a modulation and coding scheme (MS), or a timing advance (TA). 
     
     
         8 . An apparatus for wireless communication, comprising:
 at least one processor; and   memory coupled with the at least one processor, the memory storing instructions executable by the at least one processor to cause the apparatus to:   send signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   receive an uplink acknowledgement message from a user equipment (UE), responsive to a downlink message, during the second TTI.   
     
     
         9 . The apparatus of  claim 8 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
 determine a guard period during the first TTI of the first duration in the first component carrier;   determine an additional TTI of the second duration during the guard period; and   receive an additional uplink message during the additional TTI of the second duration.   
     
     
         10 . The apparatus of  claim 8 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
 receive the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         11 . The apparatus of  claim 8 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         12 . The apparatus of  claim 8 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
 receive a SRS, from a second UE different from the UE, on the SRS portion of the plurality of uplink symbols in the first TTI.   
     
     
         13 . The apparatus of  claim 8 , wherein the first TTI comprises one or more slots, each slot comprising two or more symbols of the plurality of uplink symbols. 
     
     
         14 . The apparatus of  claim 8 , wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of the UE, a modulation and coding scheme (MS), or a timing advance (TA). 
     
     
         15 . A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by at least one processor to:
 send signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   receive an uplink acknowledgement message from a user equipment (UE), responsive to a downlink message, during the second TTI.   
     
     
         16 . The non-transitory computer-readable medium of  claim 15 , wherein the instructions are further executable to:
 determine a guard period during the first TTI of the first duration in the first component carrier;   determine an additional TTI of the second duration during the guard period; and   receive an additional uplink message during the additional TTI of the second duration.   
     
     
         17 . The non-transitory computer-readable medium of  claim 15 , wherein the instructions are further executable to:
 receive the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         18 . The non-transitory computer-readable medium of  claim 15 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         19 . The non-transitory computer-readable medium of  claim 15 , wherein the instructions are further executable to:
 receive a SRS, from a second UE different from the UE, on the SRS portion of the plurality of uplink symbols in the first TTI.   
     
     
         20 . The non-transitory computer-readable medium of  claim 15 , wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of the UE, a modulation and coding scheme (MS), or a timing advance (TA). 
     
     
         21 . An apparatus for wireless communication, comprising:
 means for sending signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   means for receiving an uplink acknowledgement message from a user equipment (UE), responsive to a downlink message, during the second TTI.   
     
     
         22 . The apparatus of  claim 21 , further comprising:
 means for determining a guard period during the first TTI of the first duration in the first component carrier;   means for determining an additional TTI of the second duration during the guard period; and   means for receiving an additional uplink message during the additional TTI of the second duration.   
     
     
         23 . The apparatus of  claim 21 , further comprising:
 means for receiving the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         24 . The apparatus of  claim 21 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         25 . The apparatus of  claim 21 , further comprising:
 means for receiving a SRS, from a second UE different from the UE, on the SRS portion of the plurality of uplink symbols in the first TTI.   
     
     
         26 . The apparatus of  claim 21 , wherein the first TTI comprises one or more slots, each slot comprising two or more symbols of the plurality of uplink symbols. 
     
     
         27 . The apparatus of  claim 21 , wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of the UE, a modulation and coding scheme (MS), or a timing advance (TA). 
     
     
         28 . A method for wireless communication at a user equipment (UE), comprising:
 receiving signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   transmitting an uplink acknowledgement message, responsive to a downlink message, during the second TTI.   
     
     
         29 . The method of  claim 28 , further comprising:
 identifying a guard period during the first TTI of the first duration in the first component carrier;   identifying an additional TTI of the second duration during the guard period; and   transmitting an additional uplink message during the additional TTI of the second duration.   
     
     
         30 . The method of  claim 28 , further comprising:
 transmitting the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         31 . The method of  claim 28 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         32 . The method of  claim 28 , wherein the first TTI comprises one or more slots, each slot comprising two or more symbols of the plurality of uplink symbols. 
     
     
         33 . The method of  claim 28 , wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of the UE, a modulation and coding scheme (MS), or a timing advance (TA). 
     
     
         34 . An apparatus for wireless communication, comprising:
 at least one processor; and   memory coupled with the at least one processor, the memory storing instructions executable by the at least one processor to cause the apparatus to:   receive signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   transmit an uplink acknowledgement message, responsive to a downlink message, during the second TTI.   
     
     
         35 . The apparatus of  claim 34 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
 identify a guard period during the first TTI of the first duration in the first component carrier;   identify an additional TTI of the second duration during the guard period; and   transmit an additional uplink message during the additional TTI of the second duration.   
     
     
         36 . The apparatus of  claim 34 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
 transmit the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         37 . The apparatus of  claim 34 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         38 . The apparatus of  claim 34 , wherein the first TTI comprises one or more slots, each slot comprising two or more symbols of the plurality of uplink symbols. 
     
     
         39 . The apparatus of  claim 34 , wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of a user equipment (UE), a modulation and coding scheme (MS), or a timing advance (TA). 
     
     
         40 . A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by at least one processor to:
 receive signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   transmit an uplink acknowledgement message, responsive to a downlink message, during the second TTI.   
     
     
         41 . The non-transitory computer-readable medium of  claim 40 , wherein the instructions are further executable to:
 identify a guard period during the first TTI of the first duration in the first component carrier;   identify an additional TTI of the second duration during the guard period; and   transmit an additional uplink message during the additional TTI of the second duration.   
     
     
         42 . The non-transitory computer-readable medium of  claim 40 , wherein the instructions are further executable to:
 transmit the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         43 . The non-transitory computer-readable medium of  claim 40 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         44 . The non-transitory computer-readable medium of  claim 43 ,
 wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of a user equipment (UE), a modulation and coding scheme (MS), or a timing advance (TA).   
     
     
         45 . An apparatus for wireless communication, comprising:
 means for receiving signaling for identification of a second transmission time interval (TTI) of a second duration in a second component carrier, the second TTI comprising a portion of a plurality of uplink symbols in a first TTI of a first duration in a first component carrier in a time division duplexing (TDD) configuration, wherein the second duration is less than the first duration and the second TTI is different from a sounding reference signal (SRS) portion of the plurality of uplink symbols in the first TTI; and   means for transmitting an uplink acknowledgement message, responsive to a downlink message, during the second TTI.   
     
     
         46 . The apparatus of  claim 45 , further comprising:
 means for identifying a guard period during the first TTI of the first duration in the first component carrier;   means for identifying an additional TTI of the second duration during the guard period; and   means for transmitting an additional uplink message during the additional TTI of the second duration.   
     
     
         47 . The apparatus of  claim 45 , further comprising:
 means for transmitting the uplink acknowledgement message during a time period that comprises the second TTI and a portion of an uplink TTI of the first duration in the TDD configuration.   
     
     
         48 . The apparatus of  claim 45 , wherein the plurality of uplink symbols in the first TTI is included in a special subframe or slot. 
     
     
         49 . The apparatus of  claim 45 , wherein the first TTI comprises one or more slots, each slot comprising two or more symbols of the plurality of uplink symbols. 
     
     
         50 . The apparatus of  claim 45 , wherein a delay between the downlink message and the uplink acknowledgement message is based on at least one of: a capability of a user equipment (UE), a modulation and coding scheme (MS), or a timing advance (TA).