Patent Publication Number: US-2019174496-A1

Title: Ul scheduling timing in tdd with 1 ms tti and reduced processing time

Description:
RELATED APPLICATIONS 
     This application claims the benefit of provisional patent application Ser. No. 62/374,446, filed Aug. 12, 2016, the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to uplink scheduling timing in a Time Division Duplexing (TDD) system. 
     BACKGROUND 
     In Third Generation Partnership Project (3GPP) Technical Specification (TS) 36.211, three radio frame structures are supported. Frame Structure (FS) type 1 (FS 1) is applicable to Frequency Division Duplexing (FDD) only, FS type 2 (FS 2) is applicable to Time Division Duplexing (TDD) only, and FS type 3 (FS 3) is applicable to License Assisted Access (LAA) secondary cell operation only. 
     With FS 2 for TDD, each radio frame of length 10 milliseconds (ms) consists of two half-frames of length 5 ms each. Each half-frame consists of five Subframes (SFs) of length 1 ms. Each SF is defined by two slots of length 0.5 ms each. Within each radio frame, a subset of SFs are reserved for uplink transmissions, and the remaining SFs are allocated for downlink transmissions, or for special SFs, where the switch between downlink and uplink occurs. 
     As shown in Table 1, copied from 3GPP TS 36.211 V13.0.0, seven different downlink/uplink configurations are supported for FS 2. Here, “D” denotes a downlink SF, “U” denotes an uplink SF, and “S” represents a special SF. Configurations 0, 1, 2, and 6 have 5 ms downlink-to-uplink switch-point periodicity, with the special SF existing in both SF 1 and SF 6. Configurations 3, 4, and 5 have 10 ms downlink-to-uplink switch-point periodicity, with the special SF in SF 1 only. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Downlink/Uplink Configurations 
               
            
           
           
               
               
               
            
               
                   
                 DL-to-UL 
                   
               
               
                   
                 Switch- 
               
               
                 DL/UL 
                 point 
                 SF number 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 configuration 
                 periodicity 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
               
                 0 
                 5 ms 
                 D 
                 S 
                 U 
                 U 
                 U 
                 D 
                 S 
                 U 
                 U 
                 U 
               
               
                 1 
                 5 ms 
                 D 
                 S 
                 U 
                 U 
                 D 
                 D 
                 S 
                 U 
                 U 
                 D 
               
               
                 2 
                 5 ms 
                 D 
                 S 
                 U 
                 D 
                 D 
                 D 
                 S 
                 U 
                 D 
                 D 
               
               
                 3 
                 10 ms  
                 D 
                 S 
                 U 
                 U 
                 U 
                 D 
                 D 
                 D 
                 D 
                 D 
               
               
                 4 
                 10 ms  
                 D 
                 S 
                 U 
                 U 
                 D 
                 D 
                 D 
                 D 
                 D 
                 D 
               
               
                 5 
                 10 ms  
                 D 
                 S 
                 U 
                 D 
                 D 
                 D 
                 D 
                 D 
                 D 
                 D 
               
               
                 6 
                 5 ms 
                 D 
                 S 
                 U 
                 U 
                 U 
                 D 
                 S 
                 U 
                 U 
                 D 
               
               
                   
               
            
           
         
       
     
     A special SF is split into three parts: a downlink part (Downlink Part of a Special Subframe (DwPTS)), GP (Guard Period) and an uplink part (Uplink Part of a Special Subframe (UpPTS)). The DwPTS with duration of more than three symbols can be treated as a normal downlink SF for data transmission. However, the UpPTS is not used for data transmission due to the very short duration in the first releases of Long Term Evolution (LTE). Instead, UpPTS can be used for channel sounding or random access. In LTE Release 14 the possibility of using UpPTS for data transmission will be specified for a specific special SF configuration. 
     Typically, the downlink/uplink configuration and the configuration of the special SF used in a cell are signaled as part of the system information, which is included in System Information Block 1 (SIB1) and broadcasted every 80 ms within SF 5. 
     Hybrid Automatic Repeat Request (HARQ) timing is defined as the time relation between the reception of data in a certain HARQ process and the transmission of the HARQ acknowledgement. Based on this timing, the receiver is able to know to which HARQ process a received acknowledgement is associated. 
     In TDD, an uplink HARQ acknowledgement is only allowed to be transmitted in an uplink SF, and a downlink HARQ acknowledgement is only possible in Physical HARQ Indicator Channel (PHICH) of downlink SF and 
     DwPTS. The HARQ acknowledgement of a transport block in SF n is transmitted in SF n+k, where k≥4. The value of k depends on the downlink/uplink configuration, and is given in Table 2 and Table 3 for downlink and uplink transmissions, respectively [3GPP TS 36.213 V13.0.1]. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 HARQ Timing k for Downlink Transmissions 
               
            
           
           
               
               
            
               
                 TDD DL/UL 
                 SF index n 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 configuration 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 4 
                 6 
                 — 
                 — 
                 — 
                 4 
                 6 
                 — 
                 — 
                 — 
               
               
                 1 
                 7 
                 6 
                 — 
                 — 
                 4 
                 7 
                 6 
                 — 
                 — 
                 4 
               
               
                 2 
                 7 
                 6 
                 — 
                 4 
                 8 
                 7 
                 6 
                 — 
                 4 
                 8 
               
               
                 3 
                 4 
                 11 
                 — 
                 — 
                 — 
                 7 
                 6 
                 6 
                 5 
                 5 
               
               
                 4 
                 12 
                 11 
                 — 
                 — 
                 8 
                 7 
                 7 
                 6 
                 5 
                 4 
               
               
                 5 
                 12 
                 11 
                 — 
                 9 
                 8 
                 7 
                 6 
                 5 
                 4 
                 13 
               
               
                 6 
                 7 
                 7 
                 — 
                 — 
                 — 
                 7 
                 7 
                 — 
                 — 
                 5 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 HARQ Timing k for Uplink Transmissions 
               
            
           
           
               
               
            
               
                 TDD DL/UL 
                 SF index n 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 configuration 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
               
                 0 
                 — 
                 — 
                 4 
                 7 
                 6 
                 — 
                 — 
                 4 
                 7 
                 6 
               
               
                 1 
                 — 
                 — 
                 4 
                 6 
                 — 
                 — 
                 — 
                 4 
                 6 
                 — 
               
               
                 2 
                 — 
                 — 
                 6 
                 — 
                 — 
                 — 
                 — 
                 6 
                 — 
                 — 
               
               
                 3 
                 — 
                 — 
                 6 
                 6 
                 6 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                 4 
                 — 
                 — 
                 6 
                 6 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                 5 
                 — 
                 — 
                 6 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                 6 
                 — 
                 — 
                 4 
                 6 
                 6 
                 — 
                 — 
                 4 
                 7 
                 — 
               
               
                   
               
            
           
         
       
     
     Uplink scheduling timing refers to the time relation between a received uplink grant in downlink SF n and the uplink transmission in uplink SF n+l. 
     In TDD, the value of l depends on the downlink/uplink configuration. For downlink/uplink configurations 1-6, the values of l are given in Table 4, copied from Table 8-2 in 3GPP TS 36.213 V13.0.1. 
     For downlink/uplink configuration 0, the value of l also depends on the Uplink Index (UI) field of the uplink Downlink Control Information (DCI) transmitted in downlink SF n:
         If the Most Significant Bit (MSB) (i.e., the left-most bit) of the UI is set to 1, the value of l is obtained from Table 4;   If the Least Significant Bit (LSB) (i.e., the right-most bit) of the UI is set to 1, the value of l is 7;   If both the MSB and the LSB of the UI are set to 1, the value of l is 7 and the value obtained from Table 4.       

     Table 5 gives the uplink scheduling timing table for TDD downlink/uplink configuration 0. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Uplink Scheduling Timing l for Uplink Transmissions 
               
            
           
           
               
               
            
               
                 TDD DL/UL 
                 SF index n 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 configuration 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
               
                 0 
                 4 
                 6 
                   
                   
                   
                 4 
                 6 
                   
                   
                   
               
               
                 1 
                   
                 6 
                   
                   
                 4 
                   
                 6 
                   
                   
                 4 
               
               
                 2 
                   
                   
                   
                 4 
                   
                   
                   
                   
                 4 
               
               
                 3 
                 4 
                   
                   
                   
                   
                   
                   
                   
                 4 
                 4 
               
               
                 4 
                   
                   
                   
                   
                   
                   
                   
                   
                 4 
                 4 
               
               
                 5 
                   
                   
                   
                   
                   
                   
                   
                   
                 4 
               
               
                 6 
                 7 
                 7 
                   
                   
                   
                 7 
                 7 
                   
                   
                 5 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Uplink Scheduling Timing l for TDD 
               
               
                 Downlink/Uplink Configuration 0 
               
            
           
           
               
               
               
               
            
               
                 UL index 
                 DL/special SF 
                 UL timing, l 
                 Scheduled UL SF index 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 10 
                 0 
                 4 
                 4 
               
               
                   
                 1 
                 6 
                 7 
               
               
                   
                 5 
                 4 
                 9 
               
               
                   
                 6 
                 6 
                 2 
               
               
                 01 
                 0 
                 7 
                 7 
               
               
                   
                 1 
                 7 
                 8 
               
               
                   
                 5 
                 7 
                 2 
               
               
                   
                 6 
                 7 
                 3 
               
               
                 11 
                 0 
                 4, 7 
                 4, 7 
               
               
                   
                 1 
                 6, 7 
                 7, 8 
               
               
                   
                 5 
                 4, 7 
                 9, 2 
               
               
                   
                 6 
                 6, 7 
                 2, 3 
               
               
                   
               
            
           
         
       
     
     Packet data latency is one of the performance metrics that vendors, operators, and also end-users (via speed test applications) regularly measure. Latency measurements are done in all phases of a radio access network system lifetime, when verifying a new software release or system component, when deploying a system, and when the system is in commercial operation. 
     Shorter latency than previous generations of 3GPP Radio Access Technology (RATs) was one performance metric that guided the design of LTE. LTE is also now recognized by the end-users to be a system that provides faster access to the Internet and lower data latencies than previous generations of mobile radio technologies. 
     Packet data latency is important not only for the perceived responsiveness of the system; it is also a parameter that indirectly influences the throughput of the system. Hypertext Transfer Protocol (HTTP)/Transmission Control Protocol (TCP) is the dominating application and transport layer protocol suite used on the Internet today. According to HTTP Archive (http://httparchive.org/trends.php), the typical size of HTTP based transactions over the Internet are in the range of a few tens of kilobytes up to one megabyte. In this size range, the TCP slow start period is a significant part of the total transport period of the packet stream. During TCP slow start the performance is latency limited. Hence, improved latency can rather easily be showed to improve the average throughput for this type of TCP based data transactions. 
     Radio resource efficiency could be positively impacted by latency reductions. Lower packet data latency could increase the number of transmissions possible within a certain delay bound; hence, higher Block Error Rate (BLER) targets could be used for the data transmissions freeing up radio resources potentially improving the capacity of the system. 
     One key factor to achieve packet latency reductions is the reduction of processing time for data and control signaling. In LTE Release 8, a downlink Transmission Time Interval (TTI) n corresponds to one SF of length 1 ms and it requires 3 ms for the User Equipment device (UE) to detect the downlink assignment, decode the downlink data, and prepare the HARQ feedback to be sent in uplink. The HARQ feedback in uplink is then sent in the uplink TTI n+4. This is valid for FDD. For TDD, the timing is minimum n+4 but can be later depending on the TDD uplink/downlink configuration. The exact HARQ timing for TDD is given in form of tables in the specifications as mentioned earlier. Similarly, if the enhanced or evolved Node B (eNB) sends an uplink grant in the downlink TTI n, the uplink transmission occurs in uplink TTI n+4 in FDD or n+4 or later for TDD. 
     SUMMARY 
     Systems and methods relating to uplink scheduling timing for reduced processing time are disclosed. In some embodiments, a method of operation of a wireless device in a cellular communications network comprises receiving an uplink grant in a Transmission Time Interval (TTI) n, determining an uplink scheduling timing l based on a configured Time Division Duplexing (TDD) uplink/downlink configuration, and transmitting, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. The uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, the uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, the uplink grant schedules multiple uplink TTIs for the same wireless device. 
     In some embodiments, the uplink grant comprises an indication of one or more uplink TTIs for which the uplink grant is valid. 
     In some embodiments, an uplink part of special Subframes (SFs) can be used for uplink data transmission, and determining the uplink scheduling timing l comprises determining the uplink scheduling timing l in such a manner that the uplink part of the special SFs are treated as uplink TTIs. In some other embodiments, determining the uplink scheduling timing l comprises determining the uplink scheduling timing l in such a manner that the uplink part of the special SFs are not treated as uplink TTIs. 
     In some embodiments, the configured TDD uplink/downlink configuration is Long Term Evolution (LTE) TDD uplink/downlink configuration 1, and determining the uplink scheduling timing l comprises determining the uplink scheduling timing l such that the uplink scheduling timing l is 3 if n=0, the uplink scheduling timing l is 5 if n=1, the uplink scheduling timing l is 3 if n=4, the uplink scheduling timing l is 3 if n=5, the uplink scheduling timing l is 5 if n=6, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 2, and determining the uplink scheduling timing l comprises determining the uplink scheduling timing l such that the uplink scheduling timing l is 3 if n=3, the uplink scheduling timing l is 3 if n=4, the uplink scheduling timing l is 3 if n=8, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 3, and determining the uplink scheduling timing l comprises determining the uplink scheduling timing l such that the uplink scheduling timing l is 3 if n=0, the uplink scheduling timing l is 3 if n=1, the uplink scheduling timing l is 3 if n=8, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 4, and determining the uplink scheduling timing l comprises determining the uplink scheduling timing l such that the uplink scheduling timing l is 3 if n=0, the uplink scheduling timing l is 3 if n=8, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 5, and determining the uplink scheduling timing l comprises determining the uplink scheduling timing l such that the uplink scheduling timing l is 3 if n=8 and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, determining the uplink scheduling timing l comprises determining the uplink scheduling timing l based on the configured TDD uplink/downlink configuration and an Uplink Index (UI) comprises the uplink grant received in the TTI n. 
     In some embodiments, the TTI n and the TTI n+l are 1 millisecond (ms) TTIs. 
     Embodiments of a wireless device for a cellular communications network are also disclosed. In some embodiments, a wireless device for a cellular communications network is adapted to receive an uplink grant in a TTI n, determine an uplink scheduling timing l based on a configured TDD uplink/downlink configuration, and transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. The uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, the wireless device is further adapted to perform the method of operation of a wireless device according to any other embodiments of the method of operation of a wireless device disclosed herein. 
     In some embodiments, a wireless device for a cellular communications network comprises at least one transceiver, at least one processor, and memory comprising instructions executable by the at least one processor whereby the wireless device is operable to receive an uplink grant in a TTI n, determine an uplink scheduling timing l based on a configured TDD uplink/downlink configuration, and transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. The uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, a wireless device for a cellular communications network comprises a receiving module, a determining module, and a transmitting module. The receiving module is operable to receive an uplink grant in a TTI n. The determining module is operable to determine an uplink scheduling timing l based on a configured TDD uplink/downlink configuration. The transmitting module is operable to transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. The uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     Embodiments of a method of operation of a radio access node in a cellular communications network are also disclosed. In some embodiments, a method of operation of a radio access node in a cellular communications network comprises transmitting an uplink grant to a wireless device in a TTI n and receiving, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing l and is a function of a configured TDD uplink/downlink configuration. The uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, the uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, the uplink grant schedules multiple uplink TTIs for the same wireless device. 
     In some embodiments, the uplink grant comprises an indication of one or more uplink TTIs for which the uplink grant is valid. 
     In some embodiments, an uplink part of special SFs can be used for uplink data transmission, and the uplink scheduling timing l is determined in such a manner that the uplink part of the special SFs are treated as uplink TTIs. In some other embodiments, the uplink scheduling timing l is determined in such a manner that the uplink part of the special SFs are not treated as uplink TTIs. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 1, and the uplink scheduling timing l is 3 if n=0, the uplink scheduling timing l is 5 if n=1, the uplink scheduling timing l is 3 if n=4, the uplink scheduling timing l is 3 if n=5, the uplink scheduling timing l is 5 if n=6, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 2, and the uplink scheduling timing l is 3 if n=3, the uplink scheduling timing l is 3 if n=4, the uplink scheduling timing l is 3 if n=8, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 3, and the uplink scheduling timing l is 3 if n=0, the uplink scheduling timing l is 3 if n=1, the uplink scheduling timing l is 3 if n=8, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 4, and the uplink scheduling timing l is 3 if n=0, the uplink scheduling timing l is 3 if n=8, and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the configured TDD uplink/downlink configuration is LTE TDD uplink/downlink configuration 5, and the uplink scheduling timing l is 3 if n=8 and the uplink scheduling timing l is 3 if n=9. 
     In some embodiments, the uplink scheduling timing l is determined based on the configured TDD uplink/downlink configuration and a UI comprised in the uplink grant in the TTI n. 
     In some embodiments, the TTI n and the TTI n+l are 1 ms TTIs. 
     Embodiments of a radio access node for a cellular communications network are also disclosed. In some embodiments, a radio access node for a cellular communications network is adapted to transmit an uplink grant to a wireless device in a TTI n and receive, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing and is a function of a configured TDD uplink/downlink configuration. The uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, the radio access node is further adapted to perform the method of operation of a radio access node according to any other embodiments of the method of operation of a radio access node disclosed herein. 
     In some embodiments, a radio access node for a cellular communications network comprises at least one transmitter and at least one receiver, at least one processor, and memory comprising instructions executable by the at least one processor whereby the radio access node is operable to transmit an uplink grant to a wireless device in a TTI n and receive, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing and is a function of a configured TDD uplink/downlink configuration. The uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     In some embodiments, a radio access node for a cellular communications network comprises a transmitting module and a receiving module. The transmitting module is operable to transmit an uplink grant to a wireless device in a TTI n. The receiving module is operable to receive, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing and is a function of a configured TDD uplink/downlink configuration. The uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and the predefined minimum uplink scheduling timing value is 2 or 3. 
     Other embodiments of a method of operation of a wireless device in a cellular communications network are also disclosed. In some embodiments, a method of operation of a wireless device in a cellular communications network comprises receiving an uplink grant in a TTI n, determining an uplink scheduling timing l based on a configured TDD uplink/downlink configuration where the uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI, and transmitting, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. An uplink part of special SFs can be used for uplink data transmission, and determining the uplink scheduling timing l comprises determining the uplink scheduling timing l in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     In some embodiments, the predefined minimum uplink scheduling timing value is 2, 3, or 4. Further, in some embodiments, the uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to the predefined minimum uplink scheduling timing value such that n+l is an uplink TTI. 
     In some embodiments, the uplink grant schedules multiple uplink TTIs for the same wireless device. 
     In some embodiments, the uplink grant comprises an indication of one or more uplink TTIs for which the uplink grant is valid. 
     In some embodiments, determining the uplink scheduling timing l comprises determining the uplink scheduling timing l based on the configured TDD uplink/downlink configuration and a UI comprised in the uplink grant received in the TTI n. 
     In some embodiments, the TTI n and the TTI n+l are 1 ms TTIs. 
     Other embodiments of a wireless device for a cellular communications network are also disclosed. In some embodiments, a wireless device for a cellular communications network is adapted to receive an uplink grant in a TTI n, determine an uplink scheduling timing l based on a configured TDD uplink/downlink configuration where the uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI, and transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. An uplink part of special SFs can be used for uplink data transmission, and the wireless device determines the uplink scheduling timing l in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     In some embodiments, the wireless device is further adapted to perform the method of operation of a wireless device according to any other embodiments of the method of operation of a wireless device disclosed herein. 
     In some embodiments, a wireless device for a cellular communications network comprises at least one transceiver, at least one processor, and memory comprising instructions executable by the at least one processor whereby the wireless device is operable to receive an uplink grant in a TTI n, determine an uplink scheduling timing l based on a configured TDD uplink/downlink configuration where the uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI, and transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. An uplink part of special SFs can be used for uplink data transmission, and the wireless device is operable to determine the uplink scheduling timing l in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     In some embodiments, a wireless device for a cellular communications network comprises a receiving module, a determining module, and a transmitting module. The receiving module is operable to receive an uplink grant in a TTI n. The determining module is operable to determine an uplink scheduling timing l based on a configured TDD uplink/downlink configuration, the uplink scheduling timing l being a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI. The transmitting module is operable to transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. An uplink part of special SFs can be used for uplink data transmission, and the wireless device determines the uplink scheduling timing l in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     Other embodiments of method of operation of a radio access node in a cellular communications network are also disclosed. In some embodiments, a method of operation of a radio access node in a cellular communications network comprises transmitting an uplink grant to a wireless device in a TTI n and receiving, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing and the uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI. An uplink part of special SFs can be used for uplink data transmission, and the uplink scheduling timing l is determined in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     In some embodiments, the predefined minimum uplink scheduling timing value is 2, 3, or 4. Further, in some embodiments, the uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to the predefined minimum uplink scheduling timing value such that n+l is an uplink TTI. 
     In some embodiments, the uplink grant schedules multiple uplink TTIs for the same wireless device. 
     In some embodiments, the uplink grant comprises an indication of one or more uplink TTIs for which the uplink grant is valid. 
     In some embodiments, the uplink scheduling timing l is determined based on a configured TDD uplink/downlink configuration and a UI comprised in the uplink grant in the TTI n. 
     In some embodiments, the TTI n and the TTI n+l are 1 ms TTIs. 
     Other embodiments of a radio access node for a cellular communications network are also disclosed. In some embodiments, a radio access node for a cellular communications network is adapted to transmit an uplink grant to a wireless device in a TTI n and receive, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing and the uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and is a function of a configured TDD uplink/downlink configuration. An uplink part of special SFs can be used for uplink data transmission, and the uplink scheduling timing l is determined in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     In some embodiments, the radio access node is further adapted to perform the method of operation of a radio access node according to any other embodiments of the method of operation of a radio access node disclosed herein. 
     In some embodiments, a radio access node for a cellular communications network comprises at least one transmitter and at least one receiver, at least one processor, and memory comprising instructions executable by the at least one processor whereby the radio access node is operable to transmit an uplink grant to a wireless device in a TTI n and receive, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing and the uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and is a function of a configured TDD uplink/downlink configuration. An uplink part of special SFs can be used for uplink data transmission, and the uplink scheduling timing l is determined in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     In some embodiments, a radio access node for a cellular communications network comprises a transmitting module and a receiving module. The transmitting module is operable to transmit an uplink grant to a wireless device in a TTI n. The receiving module is operable to receive, in a TTI n+l, an uplink transmission from the wireless device in accordance with the uplink grant transmitted to the wireless device in the TTI n, where l is an uplink scheduling timing and the uplink scheduling timing l is a number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI and is a function of a configured TDD uplink/downlink configuration. An uplink part of special SFs can be used for uplink data transmission, and the uplink scheduling timing l is determined in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure. 
         FIG. 1  illustrates one example of a cellular communications network in which embodiments of the present disclosure may be implemented; 
         FIG. 2  illustrates the operation of the radio access node and the wireless device of  FIG. 1  according to some embodiments of the present disclosure; 
         FIGS. 3 through 5  illustrate scheduling timing for Time Division Duplexing (TDD) uplink/downlink configuration 0 according to some embodiments of the present disclosure; 
         FIGS. 6 through 8  illustrate scheduling timing for TDD uplink/downlink configuration 1 according to some embodiments of the present disclosure; 
         FIGS. 9 and 10  illustrate scheduling timing for TDD uplink/downlink configuration 2 according to some embodiments of the present disclosure; 
         FIGS. 11 through 14  illustrate scheduling timing for TDD uplink/downlink configuration 3 according to some embodiments of the present disclosure; 
         FIGS. 15 and 16  illustrate scheduling timing for TDD uplink/downlink configuration 4 according to some embodiments of the present disclosure; 
         FIGS. 17 and 18  illustrate scheduling timing for TDD uplink/downlink configuration 5 according to some embodiments of the present disclosure; 
         FIGS. 19 through 23  illustrate scheduling timing for TDD uplink/downlink configuration 6 according to some embodiments of the present disclosure; 
         FIGS. 24 through 26  illustrate embodiments of a radio access node; and 
         FIGS. 27 and 28  illustrate embodiments of a wireless device. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. 
     Radio Node: As used herein, a “radio node” is either a radio access node or a wireless device. 
     Radio Access Node: As used herein, a “radio access node” is any node in a radio access network of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., an enhanced or evolved Node B (eNB) in a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), and a relay node. 
     Core Network Node: As used herein, a “core network node” is any type of node in a Core Network (CN). Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network (PDN) Gateway (P-GW), a Service Capability Exposure Function (SCEF), or the like. 
     Wireless Device: As used herein, a “wireless device” is any type of device that has access to (i.e., is served by) a cellular communications network by wirelessly transmitting and/or receiving signals to a radio access node(s). Some examples of a wireless device include, but are not limited to, a User Equipment device (UE) in a 3GPP network and a Machine Type Communication (MTC) device. 
     Network Node: As used herein, a “network node” is any node that is either part of the radio access network or the CN of a cellular communications network/system. 
     Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP LTE terminology or terminology similar to 3GPP LTE terminology is oftentimes used. However, the concepts disclosed herein are not limited to LTE or a 3GPP system. 
     Note that, in the description herein, reference may be made to the term “cell;” however, particularly with respect to Fifth Generation (5G) concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams. 
     For LTE Release 15, it has been agreed to reduce processing time to allow for shorter latency. UE capabilities have improved and a faster processing time can be expected nowadays compared to what could be done in the first release of LTE. With reduced processing time, the inventors envision that the downlink Hybrid Automatic Repeat Request (HARQ) timing will be chosen between n+2 or n+3. Similarly with reduced processing time, the inventors envision that the uplink scheduling timing (uplink grant to uplink data delay) will be chosen between n+2 or n+3. The tables in the LTE specifications that give the uplink scheduling timing for Time Division Duplexing (TDD) do not capture the processing time reduction for uplink grant to uplink data. These tables need to be modified to achieve lower latency. 
     Moreover, by introducing data transmission in Uplink Part of a Special Subframe (UpPTS), it becomes possible to transmit Physical Uplink Shared Channel (PUSCH) within the special Subframes (SFs). This implies that uplink scheduling timing needs to be defined for uplink transmissions occurring in UpPTS. 
     Two different methods, i.e., latency optimized and load balancing, are proposed for the design of new Uplink Index (UI) scheduling timing tables for supporting reduced processing time with 1 millisecond (ms) Transmission Time Interval (TTI) operations in TDD. 
     For the latency optimized approach, the uplink scheduling grant sent in TTI n is valid for TTI n+l, where l is the smallest value larger than or equal to a predefined minimum timing (e.g., 2 or 3 ms) such that n+l is an uplink TTI. 
     For the load balancing approach, the uplink scheduling assignments are equally distributed over different downlink TTIs. 
     Methods for designing uplink scheduling timing with uplink data transmission on UpPTS are proposed. 
     The proposed solution provides new uplink scheduling timing tables to enable reduced processing time with 1 ms TTI in TDD. The latency optimized solution can offer the largest latency reduction gain. On the other hand, the load balancing based solution can simplify the control design, with reduced control signaling overhead. 
       FIG. 1  illustrates one example of a cellular communications network  10  in which embodiments of the present disclosure may be implemented. As illustrated, the cellular communications network  10  includes a radio access node  12  (e.g., a base station or eNB) and a wireless device  14 . In the embodiments described herein, the radio access node  12  and the wireless device  14  operate according to a TDD scheme in which some SFs are downlink SFs, some SFs are uplink SFs, and some SFs are special SFs. Embodiments of the present disclosure relate to uplink scheduling timing for 1 ms TTI operations in TDD. 
     Two different methods, i.e., latency optimized and load balancing, are proposed for the design of a new uplink scheduling timing table for supporting reduced processing time with 1 ms TTI operations in TDD. 
     It is further understood that the timing designs can be extended to support Carrier Aggregation (CA) with both Frequency Division Duplexing (FDD) and TDD carriers, among different TDD carriers and also among Frame Structure (FS) type 3 (FS3) carriers and TDD carriers. The timing relations that will be used are formed from the design provided in the present disclosure and extends the CA design. 
     In one embodiment, the timing relations are designed based on the latency optimized approach; that is, the uplink scheduling grant sent in TTI n is valid for TTI n+l, where l is the smallest value larger than or equal to a predefined minimum timing such that n+l is an uplink TTI. As described herein, the predefined minimum timing is 2 in some embodiments and 3 in some other embodiments. 
     In another embodiment, the timing relations are designed based on the load balancing approach; that is, the uplink scheduling assignments are equally distributed over different downlink TTIs. 
     In one embodiment, the timing relations for different downlink/uplink configurations are designed based on different approaches, i.e., some downlink/uplink configurations are designed based on the latency optimization approach while the other downlink/uplink configurations are designed based on the load balancing approach. 
     In one embodiment, if multiple uplink TTIs need to be scheduled in one downlink TTI, then the same UE is scheduled on all these uplink TTIs based on the same uplink Downlink Control Information (DCI), such that only one uplink scheduling grant needs to be sent from the downlink TTI. 
     In another embodiment, if multiple uplink TTIs need to be scheduled in one downlink TTI, then a field in the uplink DCI, e.g., a UI field, is used to signal for which uplink TTI(s) the grant is valid. If a load balancing approach is adopted to spread out the uplink grants, it can done so to consider to limit the number of bits in the uplink field, e.g. to 2 bits. 
     In one embodiment, UpPTS of the special SFs can be used for uplink data transmission, and the uplink scheduling timing for all uplink TTI transmissions are designed based on either the latency optimized approach or the load balancing approach, by treating UpPTS as an uplink TTI, i.e., by taking the scheduling of uplink data transmission in UpPTS into account. 
     In another embodiment, UpPTS of the special SFs can be used for uplink data transmission, and the uplink scheduling timing for all uplink TTI transmissions within legacy uplink SFs are firstly designed based on either the latency optimized approach or the load balancing approach, by not taking scheduling of data transmission in UpPTS into account; then, the uplink scheduling timing for data transmission in TTI(s), which consist(s) of UpPTS, is added on top of the latency optimized approach or the load balancing approach. 
     In this regard,  FIG. 2  illustrates the operation of the radio access node  12  and the wireless device  14  according to some embodiments of the present disclosure. As illustrated, the radio access node  12  transmits (e.g., broadcasts) an uplink/downlink (UL/DL) configuration (step  100 ). At some point, the radio access node  12  transmits an uplink grant to the wireless device  14  in TTI n (step  102 ). Based on the uplink/downlink configuration and the value of n, the wireless device  14  determines an uplink timing l for transmitting an uplink transmission to the radio access node  12  in accordance with the uplink grant (step  104 ). As described herein, the uplink timing l is an integer value larger than or equal to a predefined minimum timing such that TTI n+l is an uplink TTI. In some embodiments, the predefined minimum timing is 2. In some other embodiments, the predefined minimum timing is 3. In some other embodiments, the predefined minimum timing is 4. 
     As described herein, in some embodiments, the UpPTS can be used for uplink data transmission, and the wireless device  14  determines the uplink scheduling timing l in such a manner that the UpPTSs are treated as uplink TTIs. Further, in some embodiments, the predefined minimum timing is 2, 3, or 4, depending on the particular embodiment. 
     As also described herein, in some other embodiments, the UpPTS cannot be used for uplink data transmission, and the wireless device  14  determines the uplink scheduling timing l in such a manner that the UpPTSs are not treated as uplink TTIs. Further, in some embodiments, the predefined minimum timing is 2 or 3, depending on the particular embodiment. 
     As discussed herein, in some embodiments, the wireless device  14  determines the uplink timing l based on predefined tables (e.g., tables specified in a standard). As an example, the uplink timing l may be determined using the tables defined below. In some embodiments, the uplink timing l is defined in accordance with a latency optimization approach. For the latency optimized approach, the uplink timing l is the smallest value larger than or equal to a predefined minimum timing such that TTI n+l is an uplink TTI. In other embodiments, the uplink timing l is defined in accordance with a load balancing approach. Notably, as discussed above, in some embodiments, if multiple uplink TTIs need to be scheduled in one downlink TTI, then the same wireless device  12  is scheduled on all of these uplink TTIs, e.g., based on the same uplink DCI such that only one uplink scheduling grant is sent in the downlink TTI. In other embodiments, if multiple uplink TTIs need to be scheduled in one downlink TTI, then a field in the uplink DCI, e.g., a UI field, is used to signal for which uplink TTI(s) the grant is valid. If a load balancing approach is adopted to spread out the uplink grants, it can done so to consider to limit the number of bits in the uplink field, e.g. to 2 bits. Further, in some embodiments, the uplink timing l is determined (e.g., the predefined tables are defined) such that the UpPTS of the special SFs are treated as uplink TTIs. In a similar manner, the radio access node  12  knows the uplink timing l such that the radio access node  12  knows when to expect the respective uplink transmission from the wireless device  14 . The wireless device  14  transmits, and the radio access node  12  receives, the uplink transmission in TTI n+l (step  106 ). 
     In the following, deriving the uplink scheduling timing tables for reduced processing time and 1 ms TTI for different downlink/uplink configurations is shown. The uplink scheduling grant sent in TTI n is valid for TTI n+l, where l is the smallest value larger than or equal to a predefined minimum uplink timing (k 0 ) such that n+l is an uplink TTI. In the following the uplink scheduling timing for different k 0  are given. In certain cases, only the uplink scheduling timing for k 0 =3 is given but the same methodology can be applied for other values of k 0 . 
       FIGS. 3 to 5  show the scheduling timing for TDD uplink/downlink configuration 0 with and without PUSCH in UpPTS. The uplink scheduling timing is the same for the latency optimized approach and the load balancing approach. Since there are more uplink SFs to schedule than there are downlink SFs for sending the uplink grant, a downlink SF needs to schedule multiple uplink SFs. This can be done by including a field with, for instance, two bits in the uplink grant that would indicate which uplink SFs are scheduled from the same uplink grant/downlink SF. The existing uplink index in the uplink grant can be used for that purpose in this case too. Another solution for handling this multi-UE scheduling issue is to schedule the same UE to all these multiple uplink SFs by using the same uplink DCI. 
       FIGS. 3 to 5  show the case where the UI is 10 and 01 in the uplink grant. In the case where the UI is set to 11, the two uplink SFs indicated separately with 10 and 01 are scheduled. An example based on  FIG. 3 : if the uplink grant in the first downlink SF contains a field UI set to 11, both the uplink SFs 3 and 4 are scheduled. 
       FIGS. 6 to 8  show the scheduling timing for TDD uplink/downlink configuration 1 with and without PUSCH in UpPTS. The uplink scheduling timing is the same for the latency optimized approach and the load balancing approach in case of k 0 =2 or 3 ms. 
     In case of PUSCH in UpPTS and k 0 =4 ms, the latency-optimized approach leads to the situation where a downlink SF (or Downlink Part of a Special Subframe (DwPTS) of the special SF) contains the uplink grant for both UpPTS and the next uplink SF. This means that the downlink SF contains a field with two bits (similar to the UI mentioned earlier) in the uplink grant to indicate which uplink SF(s) is scheduled. The load balancing approach or the case of PUSCH in UpPTS and k 0 =4 ms does not lead to this situation but the average delay between the uplink grant to uplink data is increased by 7% compared to the latency-optimized approach. Considering this small difference in the delay, the load balancing approach appears more attractive for this configuration. 
     Another solution for handling the multi-UE scheduling issue when using the latency-optimized approach is to schedule the same UE to all these multiple uplink SFs by using the same uplink DCI. 
       FIGS. 9 and 10  show the scheduling timing for TDD uplink/downlink configuration 2 with and without PUSCH in UpPTS. The uplink scheduling timing is the same for the latency optimized approach and the load balancing approach. 
       FIGS. 11 to 14  show the scheduling timing for TDD uplink/downlink configuration 3 with and without PUSCH in UpPTS. The uplink scheduling timing is the same for the latency optimized approach and the load balancing approach in case of k 0 =4 or 3 ms. 
     In case of PUSCH in UpPTS and k 0 =2 ms, the latency-optimized approach leads to the situation where a downlink SF (or downlink part of the special SF) contains the uplink grant for two uplink SFs (see  FIG. 12  and  FIG. 14 ). This means that the downlink SF contains a field with two bits (similar to the UI mentioned earlier) in the uplink grant to indicate which uplink SF(s) is scheduled. The load balancing approach or the case of PUSCH in UpPTS and k 0 =4 ms does not lead to this situation but the average delay between the uplink grant to uplink data is longer compared to the latency-optimized approach. 
       FIGS. 15 and 16  show the scheduling timing for TDD uplink/downlink configuration 4 with and without PUSCH in UpPTS. The uplink scheduling timing is the same for the latency optimized approach and the load balancing approach. 
       FIGS. 17 and 18  show the scheduling timing for TDD uplink/downlink configuration 5 with and without PUSCH in UpPTS. The uplink scheduling timing is the same for the latency optimized approach and the load balancing approach. 
       FIGS. 19 to 23  show the scheduling timing for TDD uplink/downlink configuration 6 with and without PUSCH in UpPTS. The uplink scheduling timing is the same for the latency optimized approach and the load balancing approach in case of k 0 =4 and PUSCH in UpPTS. 
     In case of no PUSCH in UpPTS and k 0 =2 or 3 ms, the latency-optimized approach leads to the situation where a downlink SF (or downlink part of the special SF) contains the uplink grant for two uplink SFs (see  FIG. 19 ). This means that the uplink grant sent in the downlink SFs contains a field with two bits (similar to the UI mentioned earlier) to indicate which uplink SF(s) is scheduled. The load balancing approach does not lead to this situation but the average delay between the uplink grant to uplink data is increased by 28% compared to the latency-optimized approach. In that case the latency-optimized approach appears more attractive at the cost of some higher control payload (two additional bits in the uplink grant or separate uplink grants). Another solution for handling this multi-UE scheduling issue is to schedule the same UE to all these multiple uplink SFs by using the same uplink DCI. 
     In case of PUSCH in UpPTS and k 0 =2 or 3 ms, the multi-uplink scheduling issue cannot be avoided even with the load balancing approach. In this case, a field similar to UI must be used to indicate the scheduled uplink SF(s), unless these uplink SFs are scheduled to the same UE by using the same DCI. 
     In the following description, the uplink scheduling timing for different downlink/uplink configurations are summarized into tables. Note that, for all examples shown in this section, it is assumed that the minimum uplink scheduling timing is three times of the TTI length (k 0 =3). The tables will look different when the minimum timing is different. However, in that case the tables can be created from the figures in the previous section that cover k 0 =2 or k 0 =4. 
     Assuming that UpPTS does not contain PUSCH, Tables 6 and 7 give the corresponding uplink scheduling timing for 1 ms TTI and k 0 =3. 
     For TDD uplink/downlink configurations 1-6, the UE shall, upon detection of a Physical Downlink Control Channel (PDCCH)/Enhanced PDCCH (EPDCCH) with uplink DCI format in SF n intended for the UE, adjust the corresponding PUSCH transmission in SF n+k, with k given in Table 6 if the latency-optimized approach is chosen or Table 7 if the load balancing approach is chosen. 
     For TDD uplink/downlink configuration 0 the UE shall adjust the corresponding PUSCH transmission in SF n+k if the first bit of the UI in the uplink grant is set to 1 with k given in Table 6 if the latency-optimized approach is chosen or Table 7 if the load balancing approach is chosen. If the second bit of the UI in the uplink grant is set to 1 in SF n, the UE shall adjust the corresponding PUSCH transmission in SF n+3. If the UI in the uplink grant sent in SF n is set to 11, the UE shall adjust the corresponding PUSCH transmission in both SFs n+k and n+3, with k given in Table 6 if the latency-optimized approach is chosen or Table 7 if the load balancing approach is chosen. Note that the exact same behaviour can be achieved by swapping the role of the first bit of the UI and the role of the second bit. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Uplink Scheduling Timing for TDD with 1 ms TTI 
               
               
                 and Reduced Processing Time 
               
               
                 k 0  = 3 (Latency Optimized, No PUSCH in UpPTS) 
               
            
           
           
               
               
            
               
                 TDD UL/DL 
                 subframe number n 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Configuration 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 4 
                 6 
                   
                   
                 4 
                 6 
                   
                   
               
               
                 1 
                 3 
                   
                   
                 3 
                 3 
                   
                   
                 3 
               
               
                 2 
                   
                   
                   
                 3 
                   
                   
                   
                 3 
               
               
                 3 
                 3 
                 3 
                   
                   
                   
                   
                   
                 3 
               
               
                 4 
                 3 
                   
                   
                   
                   
                   
                   
                 3 
               
               
                 5 
                   
                   
                   
                   
                   
                   
                   
                 3 
               
               
                 6 
                 3 
                 3, 6 
                   
                   
                 3 
                   
                   
                 3 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Uplink Scheduling Timing for TDD with 1 ms TTI 
               
               
                 and Reduced Processing Time 
               
               
                 k 0  = 3 (Load Balancing Approach, No PUSCH in UpPTS) 
               
            
           
           
               
               
            
               
                 TDD UL/DL 
                 subframe number n 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Configuration 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 4 
                 6 
                   
                   
                 4 
                 6 
                   
                   
               
               
                 1 
                 3 
                   
                   
                 3 
                 3 
                   
                   
                 3 
               
               
                 2 
                   
                   
                   
                 3 
                   
                   
                   
                 3 
               
               
                 3 
                 3 
                 3 
                   
                   
                   
                   
                   
                 3 
               
               
                 4 
                 3 
                   
                   
                   
                   
                   
                   
                 3 
               
               
                 5 
                   
                   
                   
                   
                   
                   
                   
                 3 
               
               
                 6 
                 4 
                 6 
                   
                   
                 3 
                 6 
                   
                 4 
               
               
                   
               
            
           
         
       
     
     Assuming that UpPTS contains PUSCH, Table 8 and Table 9 give the corresponding uplink scheduling timing for 1 ms TTI and k 0 =3. 
     The UE shall upon detection of a PDCCH/EPDCCH with uplink DCI format in SF n intended for the UE, adjust the corresponding PUSCH transmission in SF n+k, with k given in Table 8 if the latency-optimized approach is chosen or Table 9 if the load balancing approach is chosen. 
     For configuration 0 and 6, a field is added in the uplink DCI to indicate which of the multiple possible SFs is scheduled to the UE. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Uplink Scheduling Timing for TDD with 1 ms TTI 
               
               
                 and Reduced Processing Time 
               
               
                 k 0  = 3 (Latency Optimized, PUSCH in UpPTS) 
               
            
           
           
               
               
            
               
                 TDD UL/DL 
                 subframe number n 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Configuration 
                 0 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
               
                 0 
                 3, 6 
                 3, 6 
                   
                   
                   
                 3, 6 
                 3, 6 
                   
                   
                   
               
               
                 1 
                 3 
                 5 
                   
                   
                 3 
                 3 
                 5 
                   
                   
                 3 
               
               
                 2 
                   
                   
                   
                 3 
                 3 
                   
                   
                   
                 3 
                 3 
               
               
                 3 
                 3 
                 3 
                   
                   
                   
                   
                   
                   
                 3 
                 3 
               
               
                 4 
                 3 
                   
                   
                   
                   
                   
                   
                   
                 3 
                 3 
               
               
                 5 
                   
                   
                   
                   
                   
                   
                   
                   
                 3 
                 3 
               
               
                 6 
                 3 
                 3, 5, 
                   
                   
                   
                 3 
                 5 
                   
                   
                 3 
               
               
                   
                   
                 6 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Uplink Scheduling Timing for TDD with 1 ms TTI 
               
               
                 and Reduced Processing Time 
               
               
                 k 0  = 3 (Load Balancing Approach, PUSCH in UpPTS) 
               
            
           
           
               
               
            
               
                 TDD UL/DL 
                 subframe number n 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Configuration 
                 0 
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     Two different methods, i.e., latency optimized and load balancing, are proposed for the design of new uplink scheduling timing tables for supporting 1 ms TTI operations with reduced processing time in TDD. 
       FIG. 24  is a schematic block diagram of the radio access node  12  according to some embodiments of the present disclosure. As illustrated, the radio access node  12  includes a control system  16  that includes one or more processors  18  (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory  20 , and a network interface  22 . In addition, the radio access node  12  includes one or more radio units  24  that each includes one or more transmitters  26  and one or more receivers  28  coupled to one or more antennas  30 . In some embodiments, the radio unit(s)  24  is external to the control system  16  and connected to the control system  16  via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s)  24  and potentially the antenna(s)  30  are integrated together with the control system  16 . The one or more processors  18  operate to provide one or more functions of a radio access node  12  as described herein. In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory  20  and executed by the one or more processors  18 . 
       FIG. 25  is a schematic block diagram that illustrates a virtualized embodiment of the radio access node  12  according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. Further, other types of network nodes may have similar virtualized architectures. 
     As used herein, a “virtualized” radio access node  12  is an implementation of the radio access node  12  in which at least a portion of the functionality of the radio access node  12  is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node  12  includes the control system  16  (optional) that includes the one or more processors  18  (e.g., CPUs, ASICs, FPGAs, and/or the like), the memory  20 , and the network interface  22  and the one or more radio units  24  that each includes the one or more transmitters  26  and the one or more receivers  28  coupled to the one or more antennas  30 , as described above. The control system  16  is connected to the radio unit(s)  24  via, for example, an optical cable or the like. The control system  16  is connected to one or more processing nodes  32  coupled to or included as part of a network(s)  34  via the network interface  22 . Each processing node  32  includes one or more processors  36  (e.g., CPUs, ASICs, FPGAs, and/or the like), memory  38 , and a network interface  40 . 
     In this example, functions  42  of the radio access node  12  described herein are implemented at the one or more processing nodes  32  or distributed across the control system  16  and the one or more processing nodes  32  in any desired manner. In some particular embodiments, some or all of the functions  42  of the radio access node  12  described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s)  32 . As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s)  32  and the control system  16  is used in order to carry out at least some of the desired functions  42 . Notably, in some embodiments, the control system  16  may not be included, in which case the radio unit(s)  24  communicate directly with the processing node(s)  32  via an appropriate network interface(s). 
     In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of a radio access node  12  or a node (e.g., a processing node  32 ) implementing one or more of the functions  42  of the radio access node  12  in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory). 
       FIG. 26  is a schematic block diagram of the radio access node  12  according to some other embodiments of the present disclosure. The radio access node  12  includes one or more modules  44 , each of which is implemented in software. The module(s)  44  provide the functionality of the radio access node  12  described herein. This discussion is equally applicable to the processing node  32  of  FIG. 25  where the modules  44  may be implemented at one of the processing nodes  32  or distributed across multiple processing nodes  32  and/or distributed across the processing node(s)  32  and the control system  16 . 
       FIG. 27  is a schematic block diagram of a wireless device  14  according to some embodiments of the present disclosure. As illustrated, the wireless device  14  includes one or more processors  46  (e.g., CPUs, ASICs, FPGAs, and/or the like), memory  48 , and one or more transceivers  50  each including one or more transmitters  52  and one or more receivers  54  coupled to one or more antennas  56 . In some embodiments, the functionality of the wireless device  14  described above may be fully or partially implemented in software that is, e.g., stored in the memory  48  and executed by the processor(s)  46 . 
     In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless device  14  according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory). 
       FIG. 28  is a schematic block diagram of the wireless device  14  according to some other embodiments of the present disclosure. The wireless device  14  includes one or more modules  58 , each of which is implemented in software. The module(s)  58  provide the functionality of the wireless device  14  described herein. 
     While not being limited thereto, some example embodiments of the present disclosure are provided below. 
     Embodiment 1 
     A method of operation of a wireless device ( 14 ) in a cellular communications network ( 10 ), comprising: receiving ( 102 ) an uplink grant in TTI n; determining ( 104 ), based on a configured uplink/downlink configuration, an uplink scheduling timing l; and transmitting ( 106 ), in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. 
     Embodiment 2 
     The method of embodiment 1 wherein the uplink scheduling timing l is a smallest integer number of TTIs that is larger than or equal to a predefined minimum uplink scheduling timing value such that n+l is an uplink TTI. 
     Embodiment 3 
     The method of embodiments 1 wherein the uplink scheduling timing l is defined based on a load balancing approach in which uplink scheduling grants are equally distributed over different downlink TTIs. 
     Embodiment 4 
     The method of any one of embodiments 1 to 3 wherein the uplink grant schedules multiple uplink TTIs for the same wireless device ( 14 ). 
     Embodiment 5 
     The method of embodiment 4 wherein the uplink grant comprises an indication of one or more uplink TTIs for which the uplink grant is valid. 
     Embodiment 6 
     The method of any one of embodiments 1 to 5 wherein an uplink part of special SFs can be used for uplink data transmission, and determining ( 104 ) the uplink scheduling timing l comprises determining ( 104 ) the uplink scheduling timing l in such a manner that the uplink part of the special SFs are treated as uplink TTIs. 
     Embodiment 7 
     The method of embodiment 1 or 2 wherein determining the uplink scheduling timing l comprises determining ( 104 ) the uplink scheduling timing l based on a predefined table that defines values of 1 for different values of n for the TDD uplink/downlink configuration. 
     Embodiment 8 
     The method of embodiment 7 wherein the predefined table defines the values of 1 for the different values of n for the TDD uplink/downlink configuration in such a manner that an uplink part of special SFs are treated as uplink short TTIs. 
     Embodiment 9 
     The method of embodiment 7 wherein the predefined table defines the values of 1 for the different values of n for the TDD uplink/downlink configuration in such a manner that an uplink part of special SFs are not treated as uplink short TTIs. 
     Embodiment 10 
     The method of any one of embodiments 7 to 9 wherein the predefined table defines the values of 1 for the different values of n in accordance with a latency optimization scheme. 
     Embodiment 11 
     The method of any one of embodiments 7 to 9 wherein the predefined table defines the values of l for the different values of n in accordance with a load sharing scheme. 
     Embodiment 12 
     A wireless device ( 14 ) in a cellular communications network ( 10 ), the wireless device ( 14 ) adapted to: receive an uplink grant in TTI n; determine, based on a configured uplink/downlink configuration, an uplink scheduling timing l; and transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the short TTI n. 
     Embodiment 13 
     The wireless device ( 14 ) of embodiment 12 wherein the wireless device ( 14 ) is further adapted to perform the method of any one of embodiments 2 to 11. 
     Embodiment 14 
     A wireless device ( 14 ) in a cellular communications network ( 10 ), comprising at least one transceiver ( 50 ), at least one processor ( 46 ), and memory ( 48 ) comprising instructions executable by the at least one processor ( 46 ) whereby the wireless device ( 14 ) is operable to: receive an uplink grant in TTI n; determine, based on a configured uplink/downlink configuration, an uplink scheduling timing l; and transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. 
     Embodiment 15 
     A wireless device ( 14 ) in a cellular communications network ( 10 ), the wireless device ( 14 ) comprising: a receiving module ( 58 ) operable to receive an uplink grant in TTI n; a determining module ( 58 ) operable to determine, based on a configured uplink/downlink configuration, an uplink scheduling timing l; and a transmitting module ( 58 ) operable to transmit, in a TTI n+l, an uplink transmission in accordance with the uplink grant received in the TTI n. 
     Embodiment 16 
     A method of operation of a radio access node ( 12 ) in a cellular communications network ( 10 ), comprising: transmitting ( 102 ) an uplink grant to a wireless device ( 14 ) in a TTI n; and receiving ( 106 ), in a TTI n+I, an uplink transmission from the wireless device ( 14 ) in accordance with the uplink grant transmitted to the wireless device ( 14 ) in the TTI n. 
     The following acronyms are used throughout this disclosure.
         3GPP Third Generation Partnership Project   5G Fifth Generation   ASIC Application Specific Integrated Circuit   BLER Block Error Rate   CA Carrier Aggregation   CN Core Network   CPU Central Processing Unit   DCI Downlink Control Information   DwPTS Downlink Part of a Special Subframe   eNB Enhanced or Evolved Node B   EPDCCH Enhanced Physical Downlink Control Channel   FDD Frequency Division Duplexing   FPGA Field Programmable Gate Array   FS Frame Structure   GP Guard Period   HARQ Hybrid Automatic Repeat Request   HTTP Hypertext Transfer Protocol   LAA License Assisted Access   LTE Long Term Evolution   LSB Least Significant Bit   MME Mobility Management Entity   ms Millisecond   MSB Most Significant Bit   MTC Machine Type Communication   PDCCH Physical Downlink Control Channel   PDN Packet Data Network   P-GW Packet Data Network Gateway   PHICH Physical Hybrid Automatic Repeat Request Indicator Channel   PUSCH Physical Uplink Shared Channel   RAT Radio Access Technology   SCEF Service Capability Exposure Function   SF Subframe   SIB System Information Block   TCP Transmission Control Protocol   TDD Time Division Duplexing   TS Technical Specification   TTI Transmission Time Interval   UE User Equipment   UI Uplink Index   UpPTS Uplink Part of a Special Subframe       

     Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.