Patent Publication Number: US-2022216944-A1

Title: METHOD FOR REPEATING A TRANSPORT BLOCK (TB) OVER MULTIPLE TRANSMISSION/RECEPTION POINTS (TRPs)

Description:
RELATED APPLICATIONS 
     This application claims the benefit of provisional patent application Ser. No. 62/843,063, filed May 3, 2019, the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The technology of the disclosure relates generally to Time Domain Resource 
     Allocation (TDRA) for repeating a Transport Block (TB) over multiple Transmission/Reception Points (TRPs). 
     BACKGROUND 
     The new Fifth-Generation (5G) mobile wireless communication system or New 
     Radio (NR) supports a diverse set of use cases and a diverse set of deployment scenarios. NR uses Cyclic Prefix (CP)-Orthogonal Frequency Division Multiplexing (OFDM) (CP-OFDM) in the downlink (DL) (e.g., from a network node, gNB, eNB, or base station, to a User Equipment (UE)) and both CP-OFDM and Discrete Fourier Transform (DFT)-Spread-OFDM (DFT-S-OFDM) in the Uplink (UL) (e.g., from UE to gNB). In the time domain, NR downlink and uplink physical resources are organized into equally-sized subframes of 1 millisecond (ms) each. A subframe is further divided into multiple slots of equal duration. 
     The slot length depends on subcarrier spacing. For subcarrier spacing of Δf=15 kHz, there is only one slot per subframe and each slot always consists of 14 
     OFDM symbols, irrespectively of the subcarrier spacing. 
     Typical data scheduling in NR are provided on a per slot basis. An example is shown in  FIG. 1  wherein the first two symbols contain Physical Downlink Control Channel (PDCCH) and the remaining 12 symbols contain Physical Data Channel (PDCH), which may be a Physical Downlink Shared Channel (PDSCH) or Physical Uplink Shared Channel (PUSCH). 
     Different subcarrier spacing values are supported in NR. The Supported Subcarrier Spacing (SCS) values (also referred to as different numerologies) are given by Δf=(15×2°) kHz, wherein α ∈ (0,1,2,4,8). Δf=15 kHz is the basic subcarrier spacing that is also used in Long-Term Evolution (LTE), the corresponding slot duration is 1 ms. For a given SCS, the corresponding slot duration is 1/(2°) ms. 
     In the frequency domain physical resource definition, a system bandwidth is divided into Resource Blocks (RBs), each corresponding to 12 contiguous subcarriers. The basic NR physical time-frequency resource grid is illustrated in  FIG. 2 , wherein only one RB within a 14-symbol slot is shown. One OFDM subcarrier during one OFDM symbol interval forms one Resource Element (RE). 
     Downlink transmissions can be dynamically scheduled. For example, in each slot the gNB transmits Downlink Control Information (DCI) over PDCCH to indicate which UE a UE data is transmitted to and which RBs and OFDM symbols in the current downlink slot the UE data is transmitted in. PDCCH is typically transmitted in the first one or two OFDM symbols in each slot in NR. The UE data are carried on PDSCH. A UE first detects and decodes PDCCH and, if the decoding is successful, the UE then decodes the corresponding PDSCH based on the decoded control information in the PDCCH. 
     Uplink data transmission can also be dynamically scheduled using PDCCH. Similar to downlink, a UE first decodes uplink grants in PDCCH and then transmits data over PUSCH based on the decoded control information in the uplink grant, such as modulation order, coding rate, uplink resource allocation, etc. 
     Radio Resource Control (RRC) Configuration of Number of Repetitions in Rel-15 
     In NR Rel-15, slot-aggregation is supported both for DL and UL transmissions, which is beneficial for enhancing the coverage and improved reliability. In this case, the PDSCH and PUSCH transmissions can be repeated in multiple slots when the RRC parameter for slot aggregation is configured. The corresponding RRC parameter is referred to as PDSCH-AggregationFactor, PUSCH-AggregationFactor, repK for PDSCH, grant based PUSCH, and grant-free PUSCH, respectively. The relevant Information Elements (IEs) from TS 38.331 are listed below to illustrate the usage of these parameters. 
     
       
         
           
               
             
               
                   
               
               
                 PDSCH-Config information element 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 -- ASN1START 
               
               
                 -- TAG-PDSCH-CONFIG-START 
               
            
           
           
               
               
            
               
                 PDSCH-Config ::= 
                 SEQUENCE { 
               
            
           
           
               
            
               
                 ... 
               
            
           
           
               
               
            
               
                  resourceAllocation 
                  ENUMERATED {resourceAllocationType0, 
               
            
           
           
               
            
               
                  resourceAllocationType1, dynamicSwitch}, 
               
            
           
           
               
               
            
               
                   pdsch-TimeDomainAllocationList 
                   SetupRelease { PDSCH- 
               
               
                  TimeDomainResourceAllocationList } 
                    OPTIONAL, -- Need M 
               
               
                   pdsch-AggregationFactor 
                   ENUMERATED { n2, n4, n8 } 
               
               
                   
                     OPTIONAL, -- Need 
               
            
           
           
               
            
               
                  S 
               
               
                 ... 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 PUSCH-Config information element 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 PUSCH-Config ::= 
                  SEQUENCE { 
               
            
           
           
               
            
               
                 ... 
               
            
           
           
               
               
            
               
                  resourceAllocation 
                   ENUMERATED { resourceAllocationType0, 
               
            
           
           
               
            
               
                  resourceAllocationType1, dynamicSwitch}, 
               
            
           
           
               
               
            
               
                   pusch-TimeDomainAllocationList 
                    SetupRelease { PUSCH- 
               
               
                  TimeDomainResourceAllocationList } 
                     OPTIONAL, -- Need M 
               
               
                   pusch-AggregationFactor 
                    ENUMERATED { n2, n4, n8 } 
               
               
                   
                      OPTIONAL, -- 
               
            
           
           
               
            
               
                  Need S 
               
            
           
           
               
               
            
               
                   
                 OPTIONAL, -- Need S 
               
            
           
           
               
            
               
                 ... 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 ConfiguredGrantConfig information element 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 ConfiguredGrantConfig ::= 
                 SEQUENCE { 
               
            
           
           
               
               
            
               
                   
                 ... 
               
            
           
           
               
               
               
            
               
                   
                  repK 
                 ENUMERATED {n1, n2, n4, n8}, 
               
            
           
           
               
               
            
               
                   
                 ... 
               
               
                   
                 } 
               
               
                   
                   
               
            
           
         
       
     
     When a UE is scheduled by DL assignment or DL Semi-Persistent Scheduling (SPS) for PDSCH transmission in a given slot, the signaled resource allocation for the PDSCH is used for a number of consecutive slots if aggregation factor is configured with a value larger than 1. In this case, the PDSCH is repeated with different Redundancy Versions (RVs) in those slots scheduled for transmission of corresponding Transport Blocks (TBs). The same procedure is applied for UL, wherein a UE is scheduled by UL assignment or grant-free for PUSCH transmission in a slot and configured for slot aggregations. In this case the UE uses the signaled resource allocation in the number of slots given by the aggregation factors using different RVs for the transmission of corresponding TBs. The RV to be applied on the n th  transmission occasion of the TB is determined according to table below, wherein rv id  is the RV identity number. 
     
       
         
           
               
             
               
                 TABLE 5.1.2.1-2 
               
             
            
               
                   
               
               
                 Applied redundancy version when  
               
               
                 pdsch-AggregationFactor is present 
               
            
           
           
               
               
               
            
               
                   
                 rv id  indicated  
                 rv id  to be applied to n th    
               
               
                   
                 by the DCI 
                 transmission occasion 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 scheduling  
                 n mod  
                 n mod  
                 n mod  
                 n mod  
               
               
                   
                 the PDSCH 
                 4 = 0 
                 4 = 1 
                 4 = 2 
                 4 = 3 
               
               
                   
                   
               
               
                   
                 0 
                 0 
                 2 
                 3 
                 1 
               
               
                   
                 2 
                 2 
                 3 
                 1 
                 0 
               
               
                   
                 3 
                 3 
                 1 
                 0 
                 2 
               
               
                   
                 1 
                 1 
                 0 
                 2 
                 3 
               
               
                   
                   
               
            
           
         
       
     
     In NR Rel-16, proposals for indicating the number of repetitions in DCI are being discussed. Some proposals in NR Rel-16 include indicating the number of repetitions in a newly introduced DCI field. Some other proposals in NR Rel-16 include indicating the number of repetitions using an existing DCI field, such as Time Domain Resource Allocation (TDRA) field. 
     TDRA in NR Rel-15 
     In NR Rel-15, the TDRA information for a PDSCH transmission in a slot includes such information that the UE can use to determine a slot in which the PDSCH is expected to be received (also known as K0), a starting symbol in the slot for PDSCH reception, and a length or duration of PDSCH reception (a.k.a. Start and Length Indicator Value (SLIV)). The UE is also provided with a mapping type that can be used to determine a Demodulation Reference Signal (DMRS) position. In NR, TDRA tables are specified to include different combinations of K0, SLIV, etc. The UE can be signaled an index to a row in the TDRA table that provides information on K0 and SLIV to be used for reception. 
     The similar procedure is applied for PUSCH transmissions, wherein a slot intended for PUSCH transmission is obtained from a field in UL assignment (a.k.a. K2). The SLIV information is provided in a similar way as for the DL reception as well as the mapping type by the UL assignment and/or configuration. 
     The TDRA is a time domain resource allocation for a first instant of PDSCH reception or PUSCH transmissions. As mentioned previously, if the UE is configured with the aggregation factor, the transmission in one slot will be repeated in multiple slots based on the aggregation factor. 
     The relevant IEs from TS 38.331 are listed below to illustrate the usage of these parameters. 
     
       
         
           
               
             
               
                   
               
             
            
               
                 PDSCH-TimeDomainResourceAllocationList information element 
               
               
                   
               
            
           
           
               
            
               
                 -- ASN1START 
               
               
                 -- TAG-PDSCH-TIMEDOMAINRESOURCEALLOCATIONLIST-START 
               
               
                 PDSCH-TimeDomainResourceAllocationList ::= SEQUENCE (SIZE(1..maxNrofDL- 
               
               
                 Allocations)) OF PDSCH-TimeDomainResourceAllocation 
               
               
                 PDSCH-TimeDomainResourceAllocation ::= SEQUENCE { 
               
            
           
           
               
               
               
            
               
                   
                 k0 
                 INTEGER(0..32) 
               
            
           
           
               
               
            
               
                   
                 OPTIONAL, -- Need S 
               
            
           
           
               
               
               
            
               
                   
                 mappingType 
                  ENUMERATED {typeA, typeB}, 
               
               
                   
                 startSymbolAndLength 
                   INTEGER (0..127) 
               
            
           
           
               
            
               
                 } 
               
               
                 -- TAG-PDSCH-TIMEDOMAINRESOURCEALLOCATIONLIST-STOP 
               
               
                 -- ASN1STOP 
               
               
                   
               
               
                 PDSCH-TimeDomainResourceAllocation field descriptions 
               
               
                   
               
               
                 k0 
               
               
                 The n1 corresponds to the value 1, n2 corresponds to value 2, and so on. 
               
               
                 Corresponds to L1 parameter ‘K0’ (see 38.214, section 5.1.2.1) When the field is 
               
               
                 absent the UE applies the value 0. 
               
               
                 mappingType 
               
               
                 PDSCH mapping type. (see 38.214, section 5.3) 
               
               
                 startSymbolAndLength 
               
               
                 An index giving valid combinations of start symbol and length (jointly encoded) as 
               
               
                 start and length indicator (SLIV). The network configures the field so that the 
               
               
                 allocation does not cross the slot boundary. 
               
               
                 Corresponds to L1 parameter ‘Index-start-len’ (see 38.214, section 5.1.2.1) 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
             
            
               
                 PDSCH-TimeDomainResourceAllocation information element 
               
               
                   
               
            
           
           
               
            
               
                 -- ASN1START 
               
               
                 -- TAG-PDSCH-TIMEDOMAINRESOURCEALLOCATIONLIST-START 
               
               
                 PDSCH-TimeDomainResourceAllocationList ::= SEQUENCE 
               
               
                 (SIZE(1..maxNrofDL-Allocations)) OF PDSCH- 
               
               
                 TimeDomainResourceAllocation 
               
               
                 PDSCH-TimeDomainResourceAllocation ::= SEQUENCE { 
               
            
           
           
               
               
               
            
               
                   
                  k0 
                 INTEGER(0..32)  OPTIONAL, 
               
            
           
           
               
               
            
               
                   
                  -- 
               
               
                   
                 Need S 
               
            
           
           
               
               
               
            
               
                   
                  mappingType 
                  ENUMERATED {typeA, 
               
            
           
           
               
               
            
               
                   
                 typeB}, 
               
            
           
           
               
               
               
            
               
                   
                  startSymbolAndLength 
                   INTEGER (0..127) 
               
            
           
           
               
               
            
               
                   
                 } 
               
               
                   
                 -- TAG-PDSCH-TIMEDOMAINRESOURCEALLOCATIONLIST-STOP 
               
               
                   
                   
               
            
           
           
               
            
               
                 PUSCH-TimeDomainResourceAllocationList field descriptions 
               
               
                   
               
               
                 k2 
               
               
                 Corresponds to L1 parameter ‘K2’ (see 38.214, section 6.1.2.1) When the field is 
               
               
                 absent the UE applies the value 1 when PUSCH SCS is 15/30 KHz; 2 when PUSCH 
               
               
                 SCS is 60 KHz and 3 when PUSCH SCS is 120 KHz. 
               
               
                 mappingType 
               
               
                 Mapping type. Corresponds to L1 parameter ‘Mapping-type’ (see 38.214, section 
               
               
                 6.1.2.1) 
               
               
                 startSymbolAndLength 
               
               
                 An index giving valid combinations of start symbol and length (jointly encoded) as 
               
               
                 start and length indicator (SLIV). The network configures the field so that the 
               
               
                 allocation does not cross the slot boundary. (see 38.214, section 6.1.2.1) 
               
               
                   
               
            
           
         
       
     
     Quasi Co-Located (QCL) and Transmission Configuration Indication (TCI) States 
     Several signals can be transmitted from the same base station antenna via different antenna ports. These signals can have the same large-scale properties, for instance, in terms of Doppler shift/spread, average delay spread, or average delay. These antenna ports are then said to be QCL. 
     The network can then signal to the UE that two antenna ports are QCL. If the UE knows that two antenna ports are QCL with respect to a certain parameter (e.g. Doppler spread), the UE can estimate that parameter based on one of the antenna ports and use that estimate when receiving the other antenna port. Typically, the first antenna port is represented by a measurement reference signal, such as Channel State Information (CSI)-Reference Signal (RS) (CSI-RS) (known as source RS), and the second antenna port is represented by a DMRS (known as target RS). 
     For instance, if antenna ports A and B are QCL with respect to average delay, the UE can estimate the average delay from the signal received from antenna port A (known as the source RS) and assume that the signal received from antenna port B (target RS) has the same average delay. This is useful for demodulation since the UE can know beforehand the properties of the channel when trying to measure the channel utilizing the DMRS. 
     Information about what assumptions can be made regarding QCL is signaled to the UE from the network. In NR, four types of QCL relations between a transmitted source RS and transmitted target RS were defined:
         Type A: {Doppler shift, Doppler spread, average delay, delay spread}   Type B: {Doppler shift, Doppler spread}   Type C: {average delay, Doppler shift}   Type D: {Spatial Rx parameter}       

     QCL type D was introduced to facilitate beam management with analog beamforming and is known as spatial QCL. There is currently no strict definition of spatial QCL, but the understanding is that if two transmitted antenna ports are spatially QCL, the UE can use the same Rx beam to receive them. Note that for beam management, the discussion mostly revolves around QCL Type D, but it is also necessary to convey a Type A QCL relation for the RSs to the UE, so that it can estimate all the relevant large scale parameters. 
     Typically, this is achieved by configuring the UE with a CSI-RS for Tracking RS (TRS) for time/frequency offset estimation. To be able to use any QCL reference, the UE needs to receive the TRS with a sufficiently good Signal to Interference plus Noise Ratio (SINR). In many cases, this means that the TRS has to be transmitted in a suitable beam to a certain UE. 
     To introduce dynamics in beam and Transmission/Reception Point (TRP) selection, the UE can be configured through RRC signaling with N TCI states, wherein N is up to 128 in Frequency Range 2 (FR2) and up to 8 in Frequency Range 1 (FR1), depending on UE capability. 
     Each TCI state contains QCL information, for example one or two source DL RSs, each associated with a QCL type. For example, a TCI state contains a pair of CSI-RSs each associated with a QCL type, e.g., two different CSI-RSs {CSI-RS1, CSI-RS2} is configured in the TCI state as {qcl-Type1,qcl-Type2}={Type A, Type D}. It means the UE can derive Doppler shift, Doppler spread, average delay, and delay spread from CSI-RS1 and derive the Spatial Rx parameter (e.g., the RX beam to use) from CSI-RS2. In case type D (spatial information) is not applicable, such as in low or mid band operation, then a TCI state contains only a single source RS. 
     Each of the N TCI states in the list of TCI states can be interpreted as a list of N possible beams transmitted from the network or a list of N possible TRPs used by the network to communicate with the UE. 
     A first list of available TCI states is configured for PDSCH, and a second list for PDCCH contains pointers, known as TCI State IDs, to a subset of the TCI states configured for PDSCH. The network then activates one TCI state for PDCCH (e.g., provides a TCI for PDCCH) and up to M active TCI states for PDSCH. The number M of active TCI states the UE can support is a UE capability but the maximum in NR Rel-15 is 8. 
     Each configured TCI state contains parameters for the QCL associations between source RSs (CSI-RS or SS/PBCH ports) and target RSs (e.g., PDSCH/PDCCH DMRS ports). TCI states are also used to convey QCL information for the reception of CSI-RS. 
     If a UE is configured with 4 active TCI states (from a list of 64 total configured TCI states), then 60 TCI states out of the 64 TCI states will be inactive. As such, the UE does not need to be prepared to have large scale parameters estimated for those inactive TCI states. Instead, the UE continuously tracks and updates the large-scale parameters for the 4 active TCI states by measurements and analysis of the source RSs indicated by each TCI state. 
     In NR Rel-15, when scheduling a PDSCH to a UE, the DCI contains a pointer to one active TCI. The UE is then able to determine which large-scale parameter estimate to use when performing PDSCH DMRS channel estimation and thus PDSCH demodulation. 
     DMRS 
     DMRS is used for coherent demodulation of PDSCH (DL) and PUSCH (UL), as well as of PDCCH. The DMRS is confined in RBs carrying the associated physical layer channel and is mapped on allocated REs of the OFDM time-frequency grid such that the receiver can efficiently handle time/frequency-selective fading radio channels. 
     The mapping of DMRS to REs is configurable in both frequency and time domain, with two mapping types in the frequency domain (configuration type 1 or type 2) and two mapping types in the time domain (mapping type A or type B) defining the symbol position of the first DMRS within a transmission interval. The DMRS mapping in time domain can further be single-symbol based or double-symbol based, where the latter means that DMRS is mapped in two adjacent symbols. Furthermore, a UE can be configured with one, two, three, or four single-symbol DM-RS and one or two double-symbol DMRS. In scenarios with low Doppler, it may be sufficient to configure front-loaded DMRS only, for example one single-symbol DMRS or one double-symbol DM-RS, whereas in scenarios with high Doppler additional DMRS will be required. 
       FIG. 3  shows the mapping of front-loaded DMRS for configuration type 1 and type 2 with single-symbol and double-symbol DMRS and for the mapping type A with first DMRS in third symbol of a transmission interval of 14 symbols. It can be observed from FIG. 3 that type 1 and type 2 differ with respect to both the mapping structure and the number of supported DMRS Code Division Multiplexing (CDM) groups, wherein type 1 supports 2 CDM groups and Type 2 supports 3 CDM groups. 
     The mapping structure of type 1 is sometimes referred to as a 2-comb structure with two CDM groups defined, in frequency domain, by the set of subcarriers {0,2,4, . . . } and {1,3,5, . . . }. The comb mapping structure is a prerequisite for transmissions requiring low PAPR/CM and is thus used in conjunction with DFT-S-OFDM, whereas in CP-OFDM both type 1 and type 2 mapping are supported. 
     A DMRS antenna port is mapped to the resource elements within one CDM group only. For single-symbol DMRS, two antenna ports can be mapped to each CDM group whereas for double-symbol DM-RS four antenna ports can be mapped to each CDM group. Hence, the maximum number of DMRS ports is for type 1 either four or eight and for type 2 it is either six or twelve. An Orthogonal Cover Code (OCC) of length 2 ([+1,+1],[+1, −1]) is used to separate antenna ports mapped on same resource elements within a CDM group. The OCC is applied in frequency domain as well as in time domain when double-symbol DMRS is configured. 
     In NR Rel-15, the mapping of a PDSCH DMRS sequence r(m), m=0,1, . . . on antenna port p_j and subcarrier k in OFDM symbol l for the numerology index μ is specified in TS 38.211 as: 
     
       
         
           
             
               a 
               
                 k 
                 , 
                 l 
               
               
                 ( 
                 
                   
                     p 
                     j 
                   
                   , 
                   μ 
                 
                 ) 
               
             
             = 
             
               
                 β 
                 DMRS 
                 PDSCH 
               
               ⁢ 
               
                 
                   r 
                   λ 
                   
                     ( 
                     
                       p 
                       j 
                     
                     ) 
                   
                 
                 ⁡ 
                 
                   ( 
                   
                     
                       2 
                       ⁢ 
                       n 
                     
                     + 
                     
                       k 
                       ′ 
                     
                   
                   ) 
                 
               
             
           
         
       
       
         
           
             k 
             = 
             
               { 
               
                 
                   
                     
                       
                         
                           
                             
                               4 
                               ⁢ 
                               n 
                             
                             + 
                             
                               2 
                               ⁢ 
                               
                                 k 
                                 ′ 
                               
                             
                             + 
                             Δ 
                           
                         
                         
                           
                             Configuration 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             type1 
                           
                         
                       
                       
                         
                           
                             
                               6 
                               ⁢ 
                               n 
                             
                             + 
                             
                               k 
                               ′ 
                             
                             + 
                             Δ 
                           
                         
                         
                           
                             Configuration 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             type2 
                           
                         
                       
                     
                     ⁢ 
                     
                       
 
                     
                     ⁢ 
                     
                       k 
                       ′ 
                     
                   
                   = 
                   0 
                 
                 , 
                 
                   
                     1 
                     ⁢ 
                     
                       
 
                     
                     ⁢ 
                     l 
                   
                   = 
                   
                     
                       
                         l 
                         ¯ 
                       
                       + 
                       
                         
                           l 
                           ′ 
                         
                         ⁢ 
                         
                           
 
                         
                         ⁢ 
                         n 
                       
                     
                     = 
                     0 
                   
                 
                 , 
                 1 
                 , 
                 … 
               
             
           
         
       
     
     wherein 
         r   λ   (p     j     ) (2 n+k )= w   f ( k ′) w   t ( l ′) r (2 n+k ′)
 
     represents the reference signal mapped on port p j  in CDM group λ after applying OCC in frequency domain, w f  (k′), and time domain, w t  (l′). Table 2 and Table 3 below show the PDSCH DMRS mapping parameters for configuration type 1 and type 2, respectively. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 PDSCH DMRS mapping parameters for configuration type 1. 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 CDM 
                   
                 w f  (k′) 
                   
                 w t  (l′) 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 p 
                 group λ 
                 Δ 
                 k′ = 0 
                 k′ = 1 
                 l′ = 0 
                 l′ = 1 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 1000 
                 0 
                 0 
                 +1 
                 +1 
                 +1 
                 +1 
               
               
                 1001 
                 0 
                 0 
                 +1 
                 −1 
                 +1 
                 +1 
               
               
                 1002 
                 1 
                 1 
                 +1 
                 +1 
                 +1 
                 +1 
               
               
                 1003 
                 1 
                 1 
                 +1 
                 −1 
                 +1 
                 +1 
               
               
                 1004 
                 0 
                 0 
                 +1 
                 +1 
                 +1 
                 −1 
               
               
                 1005 
                 0 
                 0 
                 +1 
                 −1 
                 +1 
                 −1 
               
               
                 1006 
                 1 
                 1 
                 +1 
                 +1 
                 +1 
                 −1 
               
               
                 1007 
                 1 
                 1 
                 +1 
                 −1 
                 +1 
                 −1 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 PDSCH DMRS mapping parameters for configuration type 2. 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 CDM 
                   
                 (k′) 
                   
                 w t  (l′) 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 p 
                 group λ 
                 Δ 
                 k′ = 0 
                 k′ = 1 
                 l′ = 0 
                 l′ = 1 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 1000 
                 0 
                 0 
                 +1 
                 +1 
                 +1 
                 +1 
               
               
                 1001 
                 0 
                 0 
                 +1 
                 −1 
                 +1 
                 +1 
               
               
                 1002 
                 1 
                 2 
                 +1 
                 +1 
                 +1 
                 +1 
               
               
                 1003 
                 1 
                 2 
                 +1 
                 −1 
                 +1 
                 +1 
               
               
                 1004 
                 2 
                 4 
                 +1 
                 +1 
                 +1 
                 +1 
               
               
                 1005 
                 2 
                 4 
                 +1 
                 −1 
                 +1 
                 +1 
               
               
                 1006 
                 0 
                 0 
                 +1 
                 +1 
                 +1 
                 −1 
               
               
                 1007 
                 0 
                 0 
                 +1 
                 −1 
                 +1 
                 −1 
               
               
                 1008 
                 1 
                 2 
                 +1 
                 +1 
                 +1 
                 −1 
               
               
                 1009 
                 1 
                 2 
                 +1 
                 −1 
                 +1 
                 −1 
               
               
                 1010 
                 2 
                 4 
                 +1 
                 +1 
                 +1 
                 −1 
               
               
                 1011 
                 2 
                 4 
                 +1 
                 −1 
                 +1 
                 −1 
               
               
                   
               
            
           
         
       
     
     QCL Relation to DMRS CDM Groups 
     In NR specification TS 38.211, there is a restriction stating that “the UE may assume that the PDSCH DMRS within the same CDM group are quasi co-located with respect to Doppler shift, Doppler spread, average delay, delay spread, and spatial Rx.” 
     In cases where a UE is not scheduled for all DMRS ports within a CDM group, there may be another UE simultaneously scheduled, using the remaining ports of that CDM group. The UE can then estimate the channel for that other UE (thus an interfering signal) in order to perform coherent interference suppression. Hence, this is useful in Multi-User-Multiple Input Multiple Output (MU-MIMO) scheduling and UE interference suppression. 
     Ultra-Reliable and Low Latency Communication (URLLC) NR 
     In NR Rel.16, there are ongoing specification enhancements for URLLC with packet error rates down to 10 −5 . For these services, an alternative Modulation and Coding Scheme (MCS) table can be configured to be used for PDSCH or PUSCH scheduling, which gives more robust reception of the data payload. 
     NR Rel-16 Enhancements for PDSCH with Multi-TRPs 
     In NR Rel-16, there are ongoing discussions on the support of PDSCH with multi-TRP. One mechanism that is being considered in NR Rel-16 is a single PDCCH scheduling one or multiple PDSCH from different TRPs. The single PDCCH is received from one of the TRPs.  FIG. 4  shows an example where a DCI received by the UE in PDCCH from TRP1 schedules two PDSCHs. The first PDSCH (PDSCH1) is received from TRP1 and the second PDSCH (PDSCH2) is received from TRP2. Alternatively, the single PDCCH schedules a single PDSCH where PDSCH layers are grouped into two groups and where layer group 1 is received from TRP1 and layer group 2 is received from TRP2. In such cases, each PDSCH or layer group is transmitted from a different TRP has a different TCI state associated with it. In the example of  FIG. 4 , PDSCH1 is associated with TCI State p, and PDSCH 2 is associated with TCI state q. 
     In the RANI. AdHoc meeting in January 2019, it has been agreed that TCI indication framework shall be enhanced in Rel-16 at least for eMBB:
         Each TCI code point in a DCI can correspond to 1 or 2 TCI states
           When 2 TCI states are activated within a TCI code point, each TCI state corresponds to one CDM group, at least for DMRS type 1
               FFS design for DMRS type 2   
               FFS: TCI field in DCI, and associated MAC-CE signaling impact   
               

     According to the above agreement, each code point in the DCI TCI field can be mapped to either 1 or 2 TCI states. This can be interpreted as “A DCI in PDCCH schedules 1 or 2 PDSCHs (or 1 or 2 layer groups if a single PDSCH) where each PDSCH or layer group is associated with a different TCI state; the code point of the TCI field in DCI indicates 1 or 2 TCI states associated with the 1 or 2 PDSCHs or layer groups scheduled.” In this case, the two DMRS of the two PDSCHs or the two layer groups are not mapped to the same DMRS CDM group. 
     It should be noted that in FR2 operation, a single PDCCH that is received by a UE using one TCI state with QCL type D (for example, single PDCCH received using one received beam) may indicate one or more PDSCHs associated with another TCI state with QCL type D (for example, one of the PDSCHs received using another received beam). In this case, the UE needs to switch beams from the point of receiving the last symbol of the single PDCCH to the point of receiving the first symbol of the PDSCH. Such beam switching delays are counted in terms of number of OFDM symbols. For example, at 60 kHz subcarrier spacing, the beam switching delay can be 7 symbols; at 120 kHz subcarrier spacing, the beam switching delay can be 14 symbols. 
     For multi-TRP based PDSCH transmission, different schemes are being considered in NR Rel-16. 
     One of the schemes that is already agreed involves slot-based time multiplexing the different PDSCHs transmitted from multiple TRPs. An example is shown in  FIG. 5 . In this example, a PDCCH indicates two different PDSCHs where PDSCH  1  associated with TCI state p is transmitted from TRP 1 and PDSCH 2 associated with TCI state q is transmitted from TRP2. Since PDSCHs 1 and 2 are time multiplexed in different slots, the DMRS corresponding to the two PDSCHs are transmitted in non-overlapping resources (e.g., different slots). Hence, the DMRSs for the two PDSCHs can use the same or different CDM group or even exactly the same antenna ports in each of the slots. In the example of  FIG. 5 , DMRS for PDSCH 1 is transmitted using CDM group 0 in slot n, while DMRS for PDSCH 2 is transmitted using CDM group 0 in slot n+ 1 . In NR Rel-16, the scheme of slot-based time-multiplexed PDSCHs associated with different TCI states is useful for URLLC. 
     Another scheme that has been agreed involves mini-slot-based time multiplexing (also known as PDSCH Type B scheduling in NR specifications) the different PDSCHs transmitted from multiple TRPs. An example is shown in  FIG. 6 . In this example, a PDCCH indicates two different PDSCHs where PDSCH 1 associated with TCI state p is transmitted from TRP 1 and PDSCH 2 associated with TCI state q is transmitted from TRP2. Since PDSCHs 1 and 2 are time multiplexed in different mini-slots, the DM-RS corresponding to the two PDSCHs are transmitted in non-overlapping resources (e.g., different mini-slots). Hence, the DMRSs for the two PDSCHs can use the same or different CDM group or even the same antenna ports in each mini-slot. In the example of  FIG. 6 , DMRS for PDSCH 1 is transmitted using CDM group 0 in mini-slot n, while DM-RS for PDSCH 2 is transmitted using CDM group 0 in mini-slot n+ 1 . In NR Rel-16, the scheme of mini-slot-based time-multiplexed PDSCHs associated with different TCI states is being considered for URLLC. 
     Note that the PDSCHs transmitted from the two TRPs in the slot-based and mini-slot based time multiplexing schemes in  FIG. 5  and  FIG. 6  may correspond to the same or different RVs of the same TB (e.g., repetitions). Hence, the UE can do soft combining of the two PDSCHs transmitted from the two TRPs to achieve more reliable reception. Even though the examples in  FIG. 5  and  FIG. 6  show two repetitions over two TRPs, the slot-based and mini-slot based time multiplexing schemes are also applicable to cases with N&gt;2 repetitions over M&gt;1 TRPs. 
     SUMMARY 
     Embodiments disclosed herein include a method for repeating a Transport Block (TB) over multiple transmission occasions. The method includes exchanging specific signaling between a wireless device (e.g., a User Equipment (UE)) and a network node (e.g., a base station) to repeat same or different redundancy versions of the TB in multiple non-overlapping transmission occasions (e.g., mini-slots) corresponding to multiple Transmission Configuration Indication (TCI) states and having different start positions. More specifically, the network node transmits a Time Domain Resource Allocation (TDRA) to indicate the multiple non-overlapping transmission occasions and the wireless device receives the TDRA indicating the multiple non-overlapping transmission occasions. Accordingly, the wireless device can receive repetition of the TB according to the TDRA. By indicating the transmission occasions in the TDRA, it is possible to efficiently schedule multiple transmission occasions over the multiple TCI states, thus helping to improve efficiency, reliability, and coverage in a wireless communications network. 
     In one embodiment, a method performed by a wireless device for repeating a TB over multiple transmission occasions is provided. The method includes receiving a TDRA from a network node, the TDRA indicating reception of a plurality of transmission occasions of a same or different redundancy versions of a TB in a plurality of non-overlapping transmission occasions corresponding to a plurality of TCI states and having a plurality of different start positions, respectively. The method also includes receiving the plurality of transmission occasions corresponding to the plurality of TCI states in the plurality of non-overlapping transmission occasions. 
     In another embodiment, each of the plurality of non-overlapping transmission occasions corresponds to a different length or duration. 
     In another embodiment, each of the plurality of non-overlapping transmission occasions corresponds to an identical length or duration. 
     In another embodiment, the method further comprises receiving the TDRA from the network node in a TDRA field of a Downlink Control Information, DCI, message. 
     In another embodiment, the method further comprises receiving a TCI field in the DCI message, the TCI field indicating the plurality of TCI states. 
     In another embodiment, a number of the plurality of transmission occasions is explicitly indicated via the TDRA received in the TDRA field. 
     In another embodiment, the number of the plurality of transmission occasions and the TDRA for each of the plurality of transmission occasions are jointly encoded and are indicated by a codepoint of the TDRA field in the DCI message. 
     In another embodiment, the TDRA corresponds to a start symbol and a length defined by a parameter ‘startSymbolAndLength’. 
     In another embodiment, the plurality of TCI states indicated in the TCI field are cycled through the indicated number of the plurality of transmission occasions, wherein a transmission occasion among the plurality of transmission occasions is associated to a TCI state among the plurality of TCI states according to an order of plurality of TCI states indicated in the TCI field. 
     In another embodiment, a first TCI state indicated in the TCI field among the plurality of TCI states is associated to a first transmission occasion among the plurality of transmission occasions. 
     In another embodiment, when a single TCI state is indicated in the TCI field, the single TCI state is associated to all the indicated number of the plurality of transmission occasions. 
     In another embodiment, a number of the plurality of transmission occasions is indicated via a number of the plurality of TCI states indicated in the TCI field. 
     In another embodiment, the plurality of TCI states indicated in the TCI field comprises a first TCI state and a second TCI state. 
     In another embodiment, an even numbered transmission occasion among the plurality of transmission occasions is associated with the first indicated TCI state and an odd numbered transmission occasion among the plurality of transmission occasions is associated with the second indicated TCI state. 
     In another embodiment, only a start symbol and a length of the odd numbered transmission occasion among the plurality of transmission occasions are indicated in the TDRA indicated by a codepoint of the TDRA field in the DCI message. 
     In another embodiment, a start symbol of the even numbered transmission occasion among the plurality of transmission occasions is determined with respect to a last symbol of an immediately preceding odd numbered transmission occasion among the plurality of transmission occasions. 
     In another embodiment, a start symbol of the even numbered transmission occasion among the plurality of transmission occasions is determined by adding one (1) to a last symbol of the immediately preceding odd numbered transmission occasion among the plurality of transmission occasions. 
     In another embodiment, the length of the even numbered transmission occasion is defined by the length of the odd numbered transmission occasion. 
     In another embodiment, a ‘PDSCH Type B’ indicated via the TDRA field in DCI message is applied to the odd numbered transmission occasion and the even numbered transmission occasion among the plurality of transmission occasions. 
     In another embodiment, the indicated plurality of TCI states correspond to a plurality of Transmission/Reception points (TRPs). 
     In another embodiment, the method further comprises receiving the TDRA from the network node for transmission of a plurality of uplink transmission occasions of a same or different redundancy versions of an uplink TB from the wireless device to the plurality of TRPs. 
     In another embodiment, the method further comprising one or more of: providing user data; and forwarding the user data to a host computer via a transmission to a base station. 
     A wireless device comprising: one or more transmitters; one or more receivers; and processing circuitry associated with the one or more transmitters and the one or more receivers, the processing circuitry configured to cause the wireless device to: receive a Time Domain Resource Allocation, TDRA, from a network node, the TDRA indicating reception of a plurality of transmission occasions of a same or different redundancy versions of the TB in a plurality of non-overlapping transmission occasions corresponding to a plurality of Transmission Configuration Indication, TCI, states and having a plurality of different start positions, respectively; and receive the plurality of transmission occasions corresponding to the plurality of TCI states in the plurality of non-overlapping transmission occasions. 
     In another embodiment, the processing circuitry is further configured to cause the wireless device to perform the method performed by the wireless device. 
     In another embodiment, a method performed by a base station for transmitting a TB over multiple transmission occasions is provided. The method includes transmitting a TDRA to a wireless device. The TDRA indicating transmission of a plurality of transmission occasions of a same or different redundancy versions of a TB in a plurality of non-overlapping transmission occasions corresponding to a plurality of TCI states and having a plurality of different start positions, respectively. The method also includes transmitting the plurality of transmission occasions corresponding to the plurality of TCI states in the plurality of non-overlapping transmission occasions. 
     In another embodiment, each of the plurality of non-overlapping transmission occasions corresponds to a different length or duration. 
     In another embodiment, each of the plurality of non-overlapping transmission occasions corresponds to an identical length or duration. 
     In another embodiment, the method further comprises transmitting the TDRA to the wireless device in a TDRA field of a DCI message. 
     In another embodiment, the method further comprises transmitting a TCI field in the DCI message, the TCI field indicating the plurality of TCI states. 
     In another embodiment, a number of the plurality of transmission occasions is explicitly indicated via the TDRA transmitted in the TDRA field. 
     In another embodiment, the number of the plurality of transmission occasions and the TDRA for each of the plurality of transmission occasions are jointly encoded and are indicated by a codepoint of the TDRA field in the DCI message. 
     In another embodiment, the TDRA corresponds to a start symbol and a length defined by a parameter ‘startSymbolAndLength’. 
     In another embodiment, the plurality of TCI states indicated in the TCI field are cycled through the indicated number of the plurality of transmission occasions, wherein a transmission occasion among the plurality of transmission occasions is associated to a TCI state among the plurality of TCI states according to an order of plurality of TCI states indicated in the TCI field. 
     In another embodiment, a first TCI state indicated in the TCI field among the plurality of TCI states is associated to a first transmission occasion among the plurality of transmission occasions. 
     In another embodiment, when a single TCI state is indicated in the TCI field, the single TCI state is associated to all the indicated number of the plurality of transmission occasions. 
     In another embodiment, a number of the plurality of transmission occasions is indicated via a number of the plurality of TCI states indicated in the TCI field. 
     In another embodiment, the plurality of TCI states indicated in the TCI field comprises a first TCI state and a second TCI state. 
     In another embodiment, an even numbered transmission occasion among the plurality of transmission occasions is associated with the first indicated TCI state and an odd numbered transmission occasion among the plurality of transmission occasions is associated with the second indicated TCI state. 
     In another embodiment, only a start symbol and a length of the odd numbered transmission occasion among the plurality of transmission occasions are indicated in the TDRA indicated by a codepoint of the TDRA field in the DCI message. 
     In another embodiment, a start symbol of the even numbered transmission occasion among the plurality of transmission occasions is determined with respect to a last symbol of an immediately preceding odd numbered transmission occasion among the plurality of transmission occasions. 
     In another embodiment, a start symbol of the even numbered transmission occasion among the plurality of transmission occasions is determined by adding one (1) to a last symbol of the immediately preceding odd numbered transmission occasion among the plurality of transmission occasions. 
     In another embodiment, the length of the even numbered transmission occasion is defined by the length of the odd numbered transmission occasion. 
     In another embodiment, a ‘PDSCH Type B’ indicated via the TDRA field in DCI message is applied to the odd numbered transmission occasion and the even numbered transmission occasion among the plurality of transmission occasions. 
     In another embodiment, the indicated plurality of TCI states corresponds to a plurality of TRPs. 
     In another embodiment, the method further comprises transmitting the TDRA to the wireless device for transmission of a plurality of uplink transmission occasions of a same or different redundancy versions of an uplink TB from the wireless device to the plurality of TRPs. 
     In another embodiment, A base station comprising: a radio unit configured to transmit a TDRA to a wireless device, the TDRA indicating transmission of a plurality of transmission occasions of a same or different redundancy versions of a TB in a plurality of non-overlapping transmission occasions corresponding to a plurality of TCI states and having a plurality of different start positions, respectively; and a control system configured to transmit the plurality of transmission occasions corresponding to the plurality of TCI states in the plurality of non-overlapping transmission occasions. 
     In another embodiment, the base station is further configured to perform the method performed by the based station. 
    
    
     
       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 an example of New Radio (NR) time-domain structure with 15 kHz subcarrier spacing; 
         FIG. 2  illustrates an example of an NR physical resource grid; 
         FIG. 3  illustrates a mapping of front-loaded Demodulation Reference Signal (DMRS) configuration type 1 and type 2; 
         FIG. 4  illustrates an example of an NR enhancement for Physical Downlink Shared Channel (PDSCH) wherein multiple PDSCHs corresponding to different Transmission Configuration Indication (TCI) states are received from multiple Transmission/Reception Points (TRPs); 
         FIG. 5  illustrates an example of slot-based time multiplexed PDSCHs from two TRPs; 
         FIG. 6  illustrates an example of mini-slot-based time multiplexed PDSCHs from two TRPs; 
         FIG. 7  illustrates one example of a cellular communications network in which embodiments of the present disclosure may be implemented; 
         FIG. 8  is a flowchart that illustrates the operation of a wireless device (e.g., a UE) configured according to some embodiments of the present disclosure to improve non-overlapping Time Domain Resource Allocation (TDRA) signalling in multi-TRP operation; 
         FIG. 9  is a flowchart that illustrates the operation of a UE to receive an indication of multiple PDSCH scheduling by a single downlink control information (DCI) message; 
         FIG. 10  is a flowchart that illustrates the operation of a base station to improve non-overlapping TDRA signalling in a multi-TRP operation; 
         FIG. 11  illustrates an example of a different repetition length in a last repetition of a slot; 
         FIG. 12  is a schematic block diagram of a radio access node according to some embodiments of the present disclosure; 
         FIG. 13  is a schematic block diagram that illustrates a virtualized embodiment of the radio access node according to some embodiments of the present disclosure; 
         FIG. 14  is a schematic block diagram of the radio access node according to some other embodiments of the present disclosure; 
         FIG. 15  is a schematic block diagram of a UE according to some embodiments of the present disclosure; 
         FIG. 16  is a schematic block diagram of the UE according to some other embodiments of the present disclosure; 
         FIG. 17  is a schematic block diagram of a communication system including a telecommunication network, such as a Third Generation Partnership Project (3GPP)-type cellular network, which comprises an access network, such as a Radio Access Network (RAN), and a core network; 
         FIG. 18  is a schematic block diagram of a UE, a base station, and a host computer according to some other embodiments of the present disclosure; 
         FIG. 19  is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure; 
         FIG. 20  is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure; 
         FIG. 21  is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure; 
       and 
         FIG. 22  is a flowchart illustrating a method implemented in a communication system in accordance with one embodiment of the present disclosure. 
     
    
    
     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. 
     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” or “radio network 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., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 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 or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing a Access and Mobility Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), 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 core network of a cellular communications network/system. 
     Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system. 
     Note that, in the description herein, reference may be made to the term “cell”; however, particularly with respect to 5G NR 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. 
       FIG. 7  illustrates one example of a cellular communications network  700  in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications network  700  is a 5G NR network. In this example, the cellular communications network  700  includes base stations  702 - 1  and  702 - 2 , which in 5G NR are referred to as gNBs, controlling corresponding macro cells  704 - 1  and  704 - 2 . The base stations  702 - 1  and  702 - 2  are generally referred to herein collectively as base stations  702  and individually as base station  702 . Likewise, the macro cells  704 - 1  and  704 - 2  are generally referred to herein collectively as macro cells  704  and individually as macro cell  704 . The cellular communications network  700  may also include a number of low power nodes  706 - 1  through  706 - 4  controlling corresponding small cells  708 - 1  through  708 - 4 . The low power nodes  706 - 1  through  706 - 4  can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells  708 - 1  through  708 - 4  may alternatively be provided by the base stations  702 . The low power nodes  706 - 1  through  706 - 4  are generally referred to herein collectively as low power nodes  706  and individually as low power node  706 . Likewise, the small cells  708 - 1  through  708 - 4  are generally referred to herein collectively as small cells  708  and individually as small cell  708 . The base stations  702  (and optionally the low power nodes  706 ) are connected to a core network  710 . 
     The base stations  702  and the low power nodes  706  provide service to wireless devices  712 - 1  through  712 - 5  in the corresponding cells  704  and  708 . The wireless devices  712 - 1  through  712 - 5  are generally referred to herein collectively as wireless devices  712  and individually as wireless device  712 . The wireless devices  712  are also sometimes referred to herein as UEs. 
     There currently exist certain challenge(s). Even though the slot-based and mini-slot based time multiplexing schemes are agreed in 3GPP for multi-Transmission/Reception Point (TRP), the signaling details for Time Domain Resource Allocation (TDRA) is still an open problem. One additional open problem is how to associate a particular Physical Downlink Shared Channel (PDSCH) transmission from a TRP to a particular repetition that may be Radio Resource Control (RRC) configured or indicated dynamically via Downlink Control Information (DCI). 
     Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. Aspects discussed herein provide a way of signaling multiple non-overlapping time domain resource allocations to a User Equipment (UE) that is configured to receive slot-based or mini-slot based time multiplexing based repetition transmitted through multiple TRPs. Examples for indicating the start symbol and lengths of each repetition are also provided. 
     There are, proposed herein, various embodiments that address one or more of the issues disclosed herein. Before describing some example embodiments in detail,  FIG. 8  is a flowchart that illustrates the operation of a wireless device (e.g., a UE) configured according to some embodiments of the present disclosure to improve non-overlapping TDRA signalling (e.g., as defined in NR Rel. 15 and/or Rel. 16) in multi-TRP operation. The wireless device may be configured to receive a TDRA (e.g., in a DCI message) from a network node, the TDRA indicates reception of a plurality of transmission occasions of same or different redundancy versions of a TB in a plurality of non-overlapping transmission occasions (e.g., multiple mini-slots) corresponding to a plurality of TCI states, respectively, wherein each of the transmission occasions corresponds to a different start position (e.g., start symbol) (block  800 ). The wireless device may also be configured to receive the multiple transmission occasions corresponding to the plurality of TCI states in the non-overlapping repetition occasions based on the scheduling (block  802 ). 
       FIG. 9  is a flowchart that illustrates the operation of a UE to receiving an indication of multiple PDSCH scheduling (repetitions) by a single DCI message. The UE may be configured to receive multiple non-overlapping TDRAs wherein the UE receives information of a start symbol and a length of each repetition (block  900 ). 
       FIG. 10  is a flowchart that illustrates the operation of base station to improve non-overlapping TDRA signalling (e.g., as defined in NR Rel. 15 and/or Rel. 16) in multi-TRP operation. The base station may be configured to transmit a TDRA (e.g., in a DCI message) to a wireless device (e.g., a UE), the TDRA indicates repetition of a plurality of transmission occasions of same or different redundancy versions of a TB in a plurality of non-overlapping transmission occasions (e.g., multiple mini-slots) corresponding to a plurality of TCI states, respectively, wherein each of the plurality of transmission occasions corresponds to a different start position (e.g., start symbol) (block  1000 ). The base station may also be configured to transmit the plurality of transmission occasions corresponding to the plurality of TCI states in the non-overlapping transmission occasions (block  1002 ). 
     Certain embodiments may provide one or more of the following technical advantage(s). The method disclosed herein provides efficient means for signaling non-overlapping TDRA to a UE such that the UE can receive slot-based or mini-slot based time multiplexed repetition transmitted through multiple TRPs. 
     TDRA for Downlink (DL) Multi-TRP Operation 
     The NR Rel-15 mechanism for TDRA using the PDSCH-TimeDomainResourceAllocationList information element may be unsuitable for multi-TRP operation since each PDSCH-TimeDomainResourceAllocation in the TimeDomainResourceAllocationList only provides one startSymbolAndLength index. In multi-TRP operation with mini-slot based time multiplexing (mini-slot is equivalent to PDSCH Type B scheduling), the start symbol of the mini-slot corresponding to different TRPs must be different. To generalize, the length of each mini-slot may also be different to give the flexibility. For example, if only six symbols are available in two mini-slots, then one four-symbol and one two-symbol mini-slot can be scheduled. 
     A key aspect of the disclosure is that the TDRA contains scheduling of multiple mini-slots, where each mini-slot may have different start positions and may also have different time duration/length. 
     In one embodiment, the TDRA field in the DCI may contain a joint encoding of the TDRA for scheduling multiple mini-slots, for example multiple PDSCH Type B scheduling. For example, a relation between the end symbol of the nth repetition can be used to define the start symbol for the (n+1)th repetition and this relation can be used to reduce the number of bits needed for TDRA of multi-slot scheduling. For example, with back to back scheduling, the nth repetition ends in symbol q, then the (n+1)th repetition starts in symbols q+ 1 . With this compression, it is only needed to indicate the start of the first repetition, the total length across all repetitions, and the number of (equal duration) repetitions. 
     In another embodiment, the starting point of the first repetition is signaled, as well as individual lengths for each repetition. As above, the (n+1)th repetition starts at the first symbol after the nth repetition, assuming back to back scheduling. In one version of this embodiment, a row in the TDRA table contains at least a starting symbol for the first repetition, and N different lengths, where N is the number of repetitions. In some versions of this embodiment, the number of repetitions is determined by the number of lengths signaled. 
     In some embodiments, the number of repetitions is signaled as one column in the TDRA table. 
     In an alternative embodiment, the length of one repetition is indicated and the total length is the product of the number of repetitions and the number of OFDM symbols per repetition. In yet another embodiment, only the start symbol and length of the first repetition are signaled. The repetition continues until the last OFDM symbol of the same slot in which the first repetition starts. The repetitions cycle through all TCI states (note one TCI state can correspond to one TRP) indicated in the TCI field of the DCI. The number of repetitions may not be signaled. For example, if two TCI states (corresponding to TRP1 and TRP2) are indicated, then the even numbered repetitions are transmitted from TRP1 and odd numbered repetitions are transmitted from TRP2. The last repetition may have a different length than the other repetitions, depending on the available OFDM symbols between the starting symbol and the last symbol in the slot. An example is shown in  FIG. 11 , in which the starting symbol # 4  with a repetition length of 4 symbols and two TCI states (corresponding to two TRPs) are signaled. The 1st repetition is transmitted from TRP1 and for the 2nd repetition, since the remaining 6 symbols are less than 2 times the signaled repetition length, all the 6 symbols are used for the second repetition from TRP2. 
     In one embodiment, a number of startSymbolAndLength indices (for example, a list of startSymbolAndLength indices) are included in each PDSCH-TimeDomainResourceAllocation. 
     In one variant of this embodiment, the startSymbolAndLength indices (e.g., the size of the list) are set equal to the number of repetitions X. The value of X may be either RRC configured or X is indicated by DCI, for example using an information element or “field” in the DCI (the DCI field can be a dedicated field of nX bits in DCI for indicating the number of repetitions or an existing field in DCI format 1-1 can be reused for this purpose). 
     In one variant of this embodiment, a number of repetitions X are jointly encoded with the time-domain resource allocations for each repetition. That is, a codepoint of the TDRA field in DCI indicates both the number of repetitions X and the startSymbolAndLength corresponding to each repetition. This can be achieved by utilizing the following ASN.1 structure to define the interpretation of the TDRA field: 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 PDSCH-TimeDomainResourceAllocationList-Rep ::= SEQUENCE 
                   
               
               
                  (SIZE(1..maxNrofDL-Allocations)) OF PDSCH- 
               
               
                 TimeDomainResourceAllocation-Rep 
               
               
                 PDSCH-TimeDomainResourceAllocation-Rep:: = SEQUENCE { 
               
               
                   nrofRepetitions 
                  INTEGER(1...maxNRofRepetitions), 
               
               
                  timeDomainResourceAllocationForEachRep SEQUENCE 
               
               
                 (SIZE(1..nrofRepetitions)) OF PDSCH-TimeDomainResourceAllocation 
               
               
                 } 
               
               
                 PDSCH-TimeDomainResourceAllocation::= SEQUENCE { 
               
               
                  mappingType 
                  ENUMERATED {typeA, typeB}, 
               
               
                 k0 
                 INTEGER(0..32) 
               
               
                   OPTIONAL, -- Need S 
               
               
                 startSymbolAndLength 
                 INTEGER (0..127) 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     In some cases, if the TCI field in DCI indicates a single TRP (e.g., one TCI state indicated in the DCI field or alternatively, if multiple states are indicated, the indicated TCI states have the same value, for example use the same entry in the list of configured TCI states), then the multiple number of startSymbolAndLength indices applies to the different PDSCH repetitions transmitted from the single TRP. In this case, the UE may assume the same TCI state holds for the PDSCH transmitted in all the scheduled repetitions. In a further embodiment, when this case applies, the UE is allowed to interpolate the channel measured from the DMRS in each of the mini-slots for all the scheduled PDSCH repetitions. Stated differently, the UE may assume that a DMRS antenna port in each of the mini-slots is valid as the same DMRS port for all mini-slot of the PDSCH repetitions, to allow channel interpolation which improves channel estimation performance. Another interpretation is that the validity region in time dimension of a DMRS antenna port used for a scheduled repetition of a PDSCH is across all scheduled repetitions of the DMRS. 
     In an alternative case, if the TCI field in DCI indicates a single TRP (e.g., one TCI state indicated in the DCI field or alternatively, if multiple states are indicated, the indicated TCI states have the same value, for example use the same entry in the list of configured TCI states), then the first index of the startSymbolAndLength indices applies to the different PDSCH repetitions transmitted from the single TRP. The embodiment related to channel interpolation from the previous paragraph can also be applied to this alternative case. 
     In the case that the TCI field in DCI indicates M&gt;1 TRPs (e.g., M different TCI states indicated in the DCI field) and the number of repetitions indicated is N&gt;2. Then, in some variants of this embodiment, the first ceil(N/M) startSymbolAndLength indices in the list correspond to different PDSCH repetitions transmitted from the first TRP associated with the first TCI state indicated in the DCI field. The next ceil(N/M), or the remaining N-ceil(N/M) startSymbolAndLength indices in the list correspond to different PDSCH repetitions transmitted from the second TRP associated with the second TCI state indicated in the DCI field. 
     Alternatively, the startSymbolAndLength indices in the list sequentially correspond to PDSCH transmissions from different TRPs. That is, the nth startSymbolAndLength index in the list corresponds to PDSCH transmission associated with TCI state mod(n,M). 
     In another embodiment, the start symbol and lengths are defined in different TDRA tables for multiple and single TRP operation. For single TRP operation, each row of the TDRA table consists of a single start symbol and a single length. For multi TRP operation, each row of the TDRA table may consist of a multiple start symbol and one or more lengths. In the multiple TRP case, at least the number of start symbols may equal the number of TRPs. As to which time domain resource allocation table is used, it may depend on the number of TCI states indicated in the TCI field in DCI. That is, if the TCI field in DCI indicates a single TCI state, then a first TDRA table for single TRP operation is used. If the TCI field in DCI indicates multiple TCI states, then a second TDRA table for multiple TRP operation is used. 
     Time Resources in Two Different Slots for Two Different TRPs 
     In another embodiment, the time domain resources of two different TRPs may reside in two different slots. Thus, in addition to startSymbolAndLength, parameter k0 need to be signaled also for each TRP. One example to signal the TDRA is illustrated below, assuming two TRPs. 
     
       
         
           
               
             
               
                   
               
             
            
               
                 PDSCH-TimeDomainResourceAllocationList-MultiTRP ::= SEQUENCE 
               
               
                 (SIZE(1..maxNrofDL-Allocations)) OF PDSCH- 
               
               
                 TimeDomainResourceAllocation-MultiTRP 
               
               
                 PDSCH-TimeDomainResourceAllocation-MultiTRP ::= SEQUENCE { 
               
            
           
           
               
               
            
               
                  mappingType 
                  ENUMERATED {typeA, typeB}, 
               
               
                 k0-TRP1 
                 INTEGER(0..32) 
               
               
                   OPTIONAL, -- Need S 
               
               
                 startSymbolAndLength-TRP1 
                   INTEGER (0..127) 
               
               
                 k0-TRP2 
                 INTEGER(0..32) 
               
               
                 OPTIONAL, -- Need S 
               
               
                 startSymbolAndLength-TRP1 
                   INTEGER (0..127) 
               
               
                   
                    } 
               
               
                   
               
            
           
         
       
     
     In another embodiment, since the slot used by TRP2 is expected to be identical to, or within the next few slots, k0-TRP2 can be signaled as a delta k0 instead, to reduce the number of bits needed. For example, the signaling may be updated to: 
     PDSCH-TimeDomainResourceAllocationList-MultiTRP ::=SEQUENCE 
     (SIZE(1 . . . maxNrofDL-Allocations)) OF PDSCH-TimeDomainResourceAllocation-MultiTRP 
     
       
         
           
               
             
               
                   
               
             
            
               
                 PDSCH-TimeDomainResourceAllocation-MultiTRP ::= SEQUENCE { 
               
            
           
           
               
               
            
               
                  mappingType 
                   ENUMERATED {typeA, 
               
               
                  typeB}, 
               
               
                 k0-TRP1 
                    INTEGER(0..32) 
               
               
                 OPTIONAL, -- Need S 
               
               
                 startSymbolAndLength-TRP1 
                 INTEGER (0..127) 
               
               
                 delta-k0-TRP2 
                  INTEGER(0..4) 
               
            
           
           
               
            
               
                   OPTIONAL, -- Need S 
               
            
           
           
               
               
            
               
                 startSymbolAndLength-TRP1 
                    INTEGER (0..127) 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     With the above, the value k0 for TRP2 is then obtained as (k0-TRP1+delta-k0-TRP2). 
     In the above, it was assumed that both TRP use the same mappingType. In general, two TRPs may use different mappingType, which requires that mappingType be signaled for each TRP separately. 
     In the above, for simplicity, it was assumed that scheduling was across two TRPs. In general, more than two TRP may be used to transmit a TB on the DL. The same methods and principles can be easily extended to apply to more-than-two TRPs. 
     TDRA for Uplink (UL) Multi-TRP Operation 
     Similar to DL data transmission, the embodiments described herein can be applied to enhance TDRA signaling for Physical Uplink Shared Channel (PUSCH) when multi-TRP operation is used. 
     For example, the embodiment can be modified to the following when applied to PUSCH scheduling. Thus, the value k2 for TRP2 is then obtained as (k2-TRP1+delta-k2-TRP2). 
     
       
         
           
               
             
               
                   
               
             
            
               
                 PUSCH-TimeDomainResourceAllocationList-MultiTRP ::= SEQUENCE 
               
               
                 (SIZE(1..maxNrofUL-Allocations)) OF PUSCH- 
               
               
                 TimeDomainResourceAllocation-MultiTRP 
               
               
                 PUSCH-TimeDomainResourceAllocation ::= SEQUENCE { 
               
            
           
           
               
               
            
               
                 MappingType 
                  ENUMERATED {typeA, typeB}, 
               
               
                 k2-TRP1 
                  INTEGER(0..32) OPTIONAL, -- 
               
               
                 Need S 
               
               
                 startSymbolAndLength-TRP1 
                 INTEGER (0..127) 
               
               
                 delta-k2-TRP2 
                  INTEGER(0..32) OPTIONAL, -- 
               
               
                 Need S 
               
               
                 startSymbolAndLength-TRP2 
                 INTEGER (0..127) 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     Additional Aspects 
       FIG. 12  is a schematic block diagram of a radio access node  1200  according to some embodiments of the present disclosure. The radio access node  1200  may be, for example, a base station  702  or  706 . As illustrated, the radio access node  1200  includes a control system  1202  that includes one or more processors  1204  (e.g., Central 
     Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory  1206 , and a network interface  1208 . The one or more processors  1204  are also referred to herein as processing circuitry. In addition, the radio access node  1200  includes one or more radio units  1210  that each includes one or more transmitters  1212  and one or more receivers  1214  coupled to one or more antennas  1216 . The radio units  1210  may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s)  1210  is external to the control system  1202  and connected to the control system  1202  via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s)  1210  and potentially the antenna(s)  1216  are integrated together with the control system  1202 . The one or more processors  1204  operate to provide one or more functions of a radio access node  1200  as described herein. In some embodiments, the function(s) is implemented in software that is stored, e.g., in the memory  1206  and executed by the one or more processors  1204 . 
       FIG. 13  is a schematic block diagram that illustrates a virtualized embodiment of the radio access node  1200  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 is an implementation of the radio access node  1200  in which at least a portion of the functionality of the radio access node  1200  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  1200  includes the control system  1202  that includes the one or more processors  1204  (e.g., CPUs, ASICs, FPGAs, and/or the like), the memory  1206 , and the network interface  1208  and the one or more radio units  1210  that each includes the one or more transmitters  1212  and the one or more receivers  1214  coupled to the one or more antennas  1216 , as described above. The control system  1202  is connected to the radio unit(s)  1210  via, for example, an optical cable or the like. The control system  1202  is connected to one or more processing nodes  1300  coupled to or included as part of a network(s)  1302  via the network interface  1208 . Each processing node  1300  includes one or more processors  1304  (e.g., CPUs, ASICs, FPGAs, and/or the like), memory  1306 , and a network interface  1308 . 
     In this example, functions  1310  of the radio access node  1200  described herein are implemented at the one or more processing nodes  1300  or distributed across the control system  1202  and the one or more processing nodes  1300  in any desired manner. In some particular embodiments, some or all of the functions  1310  of the radio access node  1200  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)  1300 . As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s)  1300  and the control system  1202  is used in order to carry out at least some of the desired functions  1310 . Notably, in some embodiments, the control system  1202  may not be included, in which case the radio unit(s)  1210  communicates directly with the processing node(s)  1300  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 the radio access node  1200  or a node (e.g., a processing node  1300 ) implementing one or more of the functions  1310  of the radio access node  1200  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. 14  is a schematic block diagram of the radio access node  1200  according to some other embodiments of the present disclosure. The radio access node  1200  includes one or more modules  1400 , each of which is implemented in software. 
     The module(s)  1400  provides the functionality of the radio access node  1200  described herein. This discussion is equally applicable to the processing node  1300  of  FIG. 13  where the modules  1400  may be implemented at one of the processing nodes  1300  or distributed across multiple processing nodes  1300  and/or distributed across the processing node(s)  1300  and the control system  1202 . 
       FIG. 15  is a schematic block diagram of a UE  1500  according to some embodiments of the present disclosure. As illustrated, the UE  1500  includes one or more processors  1502  (e.g., CPUs, ASICs, FPGAs, and/or the like), memory  1504 , and one or more transceivers  1506  each including one or more transmitters  1508  and one or more receivers  1510  coupled to one or more antennas  1512 . The transceiver(s)  1506  includes radio-front end circuitry connected to the antenna(s)  1512  that is configured to condition signals communicated between the antenna(s)  1512  and the processor(s)  1502 , as will be appreciated by one of ordinary skill in the art. The processors  1502  are also referred to herein as processing circuitry. The transceivers  1506  are also referred to herein as radio circuitry. In some embodiments, the functionality of the UE  1500  described above may be fully or partially implemented in software that is, e.g., stored in the memory  1504  and executed by the processor(s)  1502 . Note that the UE  1500  may include additional components not illustrated in  FIG. 15  such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the UE  1500  and/or allowing output of information from the UE  1500 ), a power supply (e.g., a battery and associated power circuitry), etc. 
     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 UE  1500  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. 16  is a schematic block diagram of the UE  1500  according to some other embodiments of the present disclosure. The UE  1500  includes one or more modules  1600 , each of which is implemented in software. The module(s)  1600  provides the functionality of the UE  1500  described herein. 
     With reference to  FIG. 17 , in accordance with an embodiment, a communication system includes a telecommunication network  1700 , such as a 3GPP-type cellular network, which comprises an access network  1702 , such as a RAN, and a core network  1704 . The access network  1702  comprises a plurality of base stations  1706 A,  1706 B,  1706 C, such as NBs, eNBs, gNBs, or other types of wireless Access Points (APs), each defining a corresponding coverage area  1708 A,  1708 B,  1708 C. Each base station  1706 A,  1706 B,  1706 C is connectable to the core network  1704  over a wired or wireless connection  1710 . A first UE  1712  located in coverage area  1708 C is configured to wirelessly connect to, or be paged by, the corresponding base station  1706 C. A second UE  1714  in coverage area  1708 A is wirelessly connectable to the corresponding base station  1706 A. While a plurality of UEs  1712 ,  1714  are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station  1706 . 
     The telecommunication network  1700  is itself connected to a host computer  1716 , which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server, or as processing resources in a server farm. The host computer  1716  may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Connections  1718  and  1720  between the telecommunication network  1700  and the host computer  1716  may extend directly from the core network  1704  to the host computer  1716  or may go via an optional intermediate network  1722 . The intermediate network  1722  may be one of, or a combination of more than one of, a public, private, or hosted network; the intermediate network  1722 , if any, may be a backbone network or the Internet; in particular, the intermediate network  1722  may comprise two or more sub-networks (not shown). 
     The communication system of  FIG. 17  as a whole enables connectivity between the connected UEs  1712 ,  1714  and the host computer  1716 . The connectivity may be described as an Over-the-Top (OTT) connection  1724 . The host computer  1716  and the connected UEs  1712 ,  1714  are configured to communicate data and/or signaling via the OTT connection  1724 , using the access network  1702 , the core network  1704 , any intermediate network  1722 , and possible further infrastructure (not shown) as intermediaries. The OTT connection  1724  may be transparent in the sense that the participating communication devices through which the OTT connection  1724  passes are unaware of routing of uplink and downlink communications. For example, the base station  1706  may not or need not be informed about the past routing of an incoming downlink communication with data originating from the host computer  1716  to be forwarded (e.g., handed over) to a connected UE  1712 . Similarly, the base station  1706  need not be aware of the future routing of an outgoing uplink communication originating from the UE  1712  towards the host computer  1716 . 
     Example implementations, in accordance with an embodiment, of the UE, base station, and host computer discussed in the preceding paragraphs will now be described with reference to  FIG. 18 . In a communication system  1800 , a host computer  1802  comprises hardware  1804  including a communication interface  1806  configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system  1800 . The host computer  1802  further comprises processing circuitry  1808 , which may have storage and/or processing capabilities. In particular, the processing circuitry  1808  may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The host computer  1802  further comprises software  1810 , which is stored in or accessible by the host computer  1802  and executable by the processing circuitry  1808 . The software  1810  includes a host application  1812 . The host application  1812  may be operable to provide a service to a remote user, such as a UE  1814  connecting via an OTT connection  1816  terminating at the UE  1814  and the host computer  1802 . In providing the service to the remote user, the host application  1812  may provide user data which is transmitted using the OTT connection  1816 . 
     The communication system  1800  further includes a base station  1818  provided in a telecommunication system and comprising hardware  1820  enabling it to communicate with the host computer  1802  and with the UE  1814 . The hardware  1820  may include a communication interface  1822  for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system  1800 , as well as a radio interface  1824  for setting up and maintaining at least a wireless connection  1826  with the UE  1814  located in a coverage area (not shown in  FIG. 18 ) served by the base station  1818 . The communication interface  1822  may be configured to facilitate a connection  1828  to the host computer  1802 . The connection  1828  may be direct or it may pass through a core network (not shown in  FIG. 18 ) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, the hardware  1820  of the base station  1818  further includes processing circuitry  1830 , which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The base station  1818  further has software  1832  stored internally or accessible via an external connection. 
     The communication system  1800  further includes the UE  1814  already referred to. The UE&#39;s  1814  hardware  1834  may include a radio interface  1836  configured to set up and maintain a wireless connection  1826  with a base station serving a coverage area in which the UE  1814  is currently located. The hardware  1834  of the UE  1814  further includes processing circuitry  1838 , which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The UE  1814  further comprises software  1840 , which is stored in or accessible by the UE  1814  and executable by the processing circuitry  1838 . The software  1840  includes a client application  1842 . The client application  1842  may be operable to provide a service to a human or non-human user via the UE  1814 , with the support of the host computer  1802 . In the host computer  1802 , the executing host application  1812  may communicate with the executing client application  1842  via the OTT connection  1816  terminating at the UE  1814  and the host computer  1802 . In providing the service to the user, the client application  1842  may receive request data from the host application  1812  and provide user data in response to the request data. The OTT connection  1816  may transfer both the request data and the user data. The client application  1842  may interact with the user to generate the user data that it provides. 
     It is noted that the host computer  1802 , the base station  1818 , and the UE  1814  illustrated in  FIG. 18  may be similar or identical to the host computer  1716 , one of the base stations  1706 A,  1706 B,  1706 C, and one of the UEs  1712 ,  1714  of  FIG. 17 , respectively. This is to say, the inner workings of these entities may be as shown in  FIG. 18  and independently, the surrounding network topology may be that of  FIG. 17 . 
     In  FIG. 18 , the OTT connection  1816  has been drawn abstractly to illustrate the communication between the host computer  1802  and the UE  1814  via the base station  1818  without explicit reference to any intermediary devices and the precise routing of messages via these devices. The network infrastructure may determine the routing, which may be configured to hide from the UE  1814  or from the service provider operating the host computer  1802 , or both. While the OTT connection  1816  is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network). 
     The wireless connection  1826  between the UE  1814  and the base station  1818  is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE  1814  using the OTT connection  1816 , in which the wireless connection  1826  forms the last segment. A measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection  1816  between the host computer  1802  and the UE  1814 , in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection  1816  may be implemented in the software  1810  and the hardware  1804  of the host computer  1802  or in the software  1840  and the hardware  1834  of the UE  1814 , or both. In some embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection  1816  passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which the software  1810 ,  1840  may compute or estimate the monitored quantities. The reconfiguring of the OTT connection  1816  may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not affect the base station  1818 , and it may be unknown or imperceptible to the base station  1818 . Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer  1802 &#39;s measurements of throughput, propagation times, latency, and the like. The measurements may be implemented in that the software  1810  and  1840  causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection  1816  while it monitors propagation times, errors, etc. 
       FIG. 19  is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to  FIGS. 17 and 18 . For simplicity of the present disclosure, only drawing references to  FIG. 19  will be included in this section. In step  1900 , the host computer provides user data. In sub-step  1902  (which may be optional) of step  1900 , the host computer provides the user data by executing a host application. In step  1904 , the host computer initiates a transmission carrying the user data to the UE. In step  1906  (which may be optional), the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step  1908  (which may also be optional), the UE executes a client application associated with the host application executed by the host computer. 
       FIG. 20  is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to  FIGS. 17 and 18 . For simplicity of the present disclosure, only drawing references to  FIG. 20  will be included in this section. In step  2000  of the method, the host computer provides user data. In an optional sub-step (not shown) the host computer provides the user data by executing a host application. In step  2002 , the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step  2004  (which may be optional), the UE receives the user data carried in the transmission. 
       FIG. 21  is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to  FIGS. 17 and 18 . For simplicity of the present disclosure, only drawing references to  FIG. 21  will be included in this section. In step  2100  (which may be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step  2102 , the UE provides user data. In sub-step  2104  (which may be optional) of step  2100 , the UE provides the user data by executing a client application. In sub-step  2106  (which may be optional) of step  2102 , the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in sub-step  2108  (which may be optional), transmission of the user data to the host computer. In step  2110  of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure. 
       FIG. 22  is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to  FIGS. 17 and 18 . For simplicity of the present disclosure, only drawing references to  FIG. 22  will be included in this section. In step  2200  (which may be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step  2202  (which may be optional), the base station initiates transmission of the received user data to the host computer. In step  2204  (which may be optional), the host computer receives the user data carried in the transmission initiated by the base station. 
     Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure. 
     While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.). 
     Some example embodiments of the present disclosure are as follows. 
     Group A Embodiments 
     Embodiment 1 
     A method performed by a wireless device for improving non-overlapping time domain resource allocation (TDRA) signalling (e.g., as defined in NR Rel. 15 and/or Rel. 16) in multi-TRP (transmission point) operation, the method comprising one or more of: receiving (XX800) a downlink control information (DCI) message comprising a TDRA field, the TDRA field comprising a scheduling for receiving multiple mini-slots (e.g., multiple repetitions) from multiple TRPs, respectively, wherein each of the multiple mini-slots corresponds to a different start position (e.g., start symbol); and receiving (XX802) the multiple mini-slots from the multiple TRPs based on the scheduling received in the TDRA field of the DCI message. 
     Embodiment 2 
     The method of embodiment 1, wherein each of the multiple mini-slots corresponds to a different time duration/length. 
     Embodiment 3 
     The method of any of the previous embodiments, wherein the scheduling information comprised in the TDRA field comprises a joint encoding indicating a relationship between an end position (e.g., symbol) of a selected mini-slot among the multiple mini-slots and a start position (e.g., symbol) of a succeeding mini-slot among the multiple mini-slots. 
     Embodiment 4 
     The method any of the previous embodiments, wherein the scheduling information comprised in the TDRA field comprises one or more of: an indication of a start position (e.g., symbol) of a first mini-slot (e.g., first repetition); and an indication of a respective length/duration (e.g., number of symbols) of each of the multiple mini-slots (e.g., each of the multiple repetitions). 
     Embodiment 5 
     The method of any of the previous embodiments, wherein the DCI message further comprises a TCI field, and an indication in the TCI field indicates a repetition cycle through multiple TCI states corresponding to the multiple TRPs, respectively. 
     Embodiment 6 
     The method of any of the previous embodiments, further comprising receiving multiple TDRAs from the multiple TRPs in different slots. 
     Embodiment 7 
     The method of any of the previous embodiments, further comprising one or more of: receiving even numbered mini-slots (e.g., repetitions) from a first of the multiple TRPs; and receiving odd numbered mini-slots (e.g., repetitions) from a second of the multiple TRPs. 
     Embodiment 8 
     The method of any of the previous embodiments, further comprising one or more of: providing user data; and forwarding the user data to a host computer via the transmission to the base station. 
     Embodiment 9 
     The method of any of the previous embodiments, further comprising the step of receiving a respective TDRA field for enabling uplink multi-TRP operation. 
     Embodiment 10 
     A method in a User Equipment, UE, for receiving (XX900) an indication of multiple PDSCH scheduling (repetitions) by a single downlink control information (DCI) message, comprising multiple non-overlapping time domain resource allocations wherein the UE receives information of a start symbol and a length of each repetition. 
     a. The number of repetitions may be either signaled explicitly 
     b. The number of repetitions may be implicitly derived by the UE based on the starting symbol and the length 
     c. The length of the last repetition may be the same or different from the signaled length 
     Each repetition is associated with a TCI state (i.e., TRP) according to the TCI state order indicated in the TCI field starting from the 1 st  TCI state corresponding to the 1 st  repetition. 
     Embodiment 1 
     The method according to embodiment 10, where information carried in the TCI state field in the same DCI message provides additional and required information to determine the PDSCH time resource allocation for each of the multiple, scheduled, PDSCH repetitions. 
     Group B Embodiments 
     Embodiment 12 
     A method performed by a base station for improving non-overlapping time domain resource allocation (TDRA) signalling (e.g., as defined in NR Rel. 15 and/or Rel. 16) in multi-TRP (transmission point) operation, the method comprising one or more of: transmitting (XX1000) a downlink control information (DCI) message comprising a TDRA field, the TDRA field comprising a scheduling for transmitting multiple mini-slots (e.g., multiple repetitions) from multiple TRPs, respectively, wherein each of the multiple mini-slots corresponds to a different start position (e.g., start symbol); and transmitting (XX1002) the multiple mini-slots from the multiple TRPs based on the scheduling transmitted in the TDRA field of the DCI message. 
     Embodiment 13 
     The method of embodiment 12, further comprising the step of transmitting the scheduling for transmitting multiple mini-slots from multiple TRPs, respectively, wherein each of the multiple mini-slots corresponds to a different time duration/length. 
     Embodiment 14 
     The method of any of the previous embodiments, wherein the scheduling information comprised in the TDRA field comprises a joint encoding indicating a relationship between an end position (e.g., symbol) of a selected mini-slot among the multiple mini-slots and a start position (e.g., symbol) of a succeeding mini-slot among the multiple mini-slots. 
     Embodiment 15 
     The method of any of the previous embodiments, wherein the scheduling information comprised in the TDRA field comprises one or more of: an indication of a start position (e.g., symbol) of a first mini-slot (e.g., first repetition); and an indication of a respective length/duration (e.g., number of symbols) of each of the multiple mini-slots (e.g., each of the multiple repetitions). 
     Embodiment 16 
     The method of any of the previous embodiments, wherein the DCI message further comprises a TCI field, and an indication in the TCI field of the DCI that indicates a repetition cycle through multiple TCI states corresponding to the multiple TRPs, respectively. 
     Embodiment 17 
     The method of any of the previous embodiments, further comprising the step of transmitting a respective TDRA field for enabling uplink multi-TRP operation. 
     Embodiment 18 
     The method of any of the previous embodiments, further comprising one or more of: transmitting even numbered mini-slots (e.g., repetitions) from a first of the multiple TRPs; and transmitting odd numbered mini-slots (e.g., repetitions) from a second of the multiple TRPs. 
     Embodiment 19 
     The method of any of the previous embodiments, further comprising one or more of: obtaining user data; and forwarding the user data to a host computer or a wireless device. 
     Group C Embodiments 
     Embodiment 20 
     A wireless device for improving non-overlapping time domain resource allocation (TDRA) signalling (e.g., as defined in NR Rel. 15 and/or Rel. 16) in multi-TRP (transmission point) operation, the wireless device comprising: processing circuitry configured to perform any of the steps of any of the Group A embodiments; and power supply circuitry configured to supply power to the wireless device. 
     Embodiment 21 
     A base station for improving non-overlapping time domain resource allocation (TDRA) signalling (e.g., as defined in NR Rel. 15 and/or Rel. 16) in multi-TRP (transmission point) operation, the base station comprising: processing circuitry configured to perform any of the steps of any of the Group B embodiments; and power supply circuitry configured to supply power to the base station. 
     Embodiment 22 
     A User Equipment, UE, for improving non-overlapping time domain resource allocation (TDRA) signalling (e.g., as defined in NR Rel. 15 and/or Rel. 16) in multi-TRP (transmission point) operation, the UE comprising: an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; the processing circuitry being configured to perform any of the steps of any of the Group A embodiments; an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE. 
     Embodiment 23 
     A communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a User Equipment, UE; wherein the cellular network comprises a base station having a radio interface and processing circuitry, the base station&#39;s processing circuitry configured to perform any of the steps of any of the Group B embodiments. 
     Embodiment 24 
     The communication system of the previous embodiment further including the base station. 
     Embodiment 25 
     The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station. 
     Embodiment 26 
     The communication system of the previous 3 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the UE comprises processing circuitry configured to execute a client application associated with the host application. 
     Embodiment 27 
     A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, providing user data; and at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the base station performs any of the steps of any of the Group B embodiments. 
     Embodiment 28 
     The method of the previous embodiment, further comprising, at the base station, transmitting the user data. 
     Embodiment 29 
     The method of the previous 2 embodiments, wherein the user data is provided at the host computer by executing a host application, the method further comprising, at the UE, executing a client application associated with the host application. 
     Embodiment 30 
     A User Equipment, UE, configured to communicate with a base station, the UE comprising a radio interface and processing circuitry configured to perform the method of the previous 3 embodiments. 
     Embodiment 31 
     A communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward user data to a cellular network for transmission to a User Equipment, UE; wherein the UE comprises a radio interface and processing circuitry, the UE&#39;s components configured to perform any of the steps of any of the Group A embodiments. 
     Embodiment 32 
     The communication system of the previous embodiment, wherein the cellular network further includes a base station configured to communicate with the UE. 
     Embodiment 33 
     The communication system of the previous 2 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the UE&#39;s processing circuitry is configured to execute a client application associated with the host application. 
     Embodiment 34 
     A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, providing user data; and at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the UE performs any of the steps of any of the Group A embodiments. 
     Embodiment 35 
     The method of the previous embodiment, further comprising at the UE, receiving the user data from the base station. 
     Embodiment 36 
     A communication system including a host computer comprising: communication interface configured to receive user data originating from a transmission from a User Equipment, UE, to a base station; wherein the UE comprises a radio interface and processing circuitry, the UE&#39;s processing circuitry configured to perform any of the steps of any of the Group A embodiments. 
     Embodiment 37 
     The communication system of the previous embodiment, further including the UE. 
     Embodiment 38 
     The communication system of the previous 2 embodiments, further including the base station, wherein the base station comprises a radio interface configured to communicate with the UE and a communication interface configured to forward to the host computer the user data carried by a transmission from the UE to the base station. 
     Embodiment 39 
     The communication system of the previous 3 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application; and the UE&#39;s processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data. 
     Embodiment 40 
     The communication system of the previous 4 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing request data; and the UE&#39;s processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data in response to the request data. 
     Embodiment 41 
     A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, receiving user data transmitted to the base station from the UE, wherein the UE performs any of the steps of any of the Group A embodiments. 
     Embodiment 42 
     The method of the previous embodiment, further comprising, at the UE, providing the user data to the base station. 
     Embodiment 43 
     The method of the previous 2 embodiments, further comprising: at the UE, executing a client application, thereby providing the user data to be transmitted; and at the host computer, executing a host application associated with the client application. 
     Embodiment 44 
     The method of the previous 3 embodiments, further comprising: at the UE, executing a client application; and at the UE, receiving input data to the client application, the input data being provided at the host computer by executing a host application associated with the client application; wherein the user data to be transmitted is provided by the client application in response to the input data. 
     Embodiment 45 
     A communication system including a host computer comprising a communication interface configured to receive user data originating from a transmission from a User Equipment, UE, to a base station, wherein the base station comprises a radio interface and processing circuitry, the base station&#39;s processing circuitry configured to perform any of the steps of any of the Group B embodiments. 
     Embodiment 46 
     The communication system of the previous embodiment further including the base station. 
     Embodiment 47 
     The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station. 
     Embodiment 48 
     The communication system of the previous 3 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application; and the UE is configured to execute a client application associated with the host application, thereby providing the user data to be received by the host computer. 
     Embodiment 49 
     A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, receiving, from the base station, user data originating from a transmission which the base station has received from the UE, wherein the UE performs any of the steps of any of the Group A embodiments. 
     Embodiment 50 
     The method of the previous embodiment, further comprising at the base station, receiving the user data from the UE. 
     Embodiment 51 
     The method of the previous 2 embodiments, further comprising at the base station, initiating a transmission of the received user data to the host computer. 
     At least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).
         3GPP Third Generation Partnership Project   5G Fifth Generation   AMF Access and Mobility Function   AN Access Network   AP Access Point   ASIC Application Specific Integrated Circuit   AUSF Authentication Server Function   CDM Code Division Multiplexing   CP Cyclic Prefix   CPU Central Processing Unit   CSI Channel State Information   CSI-RS Channel State Information Reference Signal   DCI Downlink Control Information   DFT Discrete Fourier Transform   DFT-S-OFDM Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing   DL Downlink   DMRS Demodulation Reference Signal   DSP Digital Signal Processor   eNB Enhanced or Evolved Node B   FPGA Field Programmable Gate Array   gNB New Radio Base Station   HSS Home Subscriber Server   IE Information Element   LTE Long Term Evolution   MCS Modulation and Coding Scheme   MME Mobility Management Entity   MTC Machine Type Communication   MU-MIMO Multiple User Multiple Input Multiple Output   NEF Network Exposure Function   NF Network Function   NR New Radio   NRF Network Function Repository Function   NSSF Network Slice Selection Function   OCC Orthogonal Cover Code   OFDM Orthogonal Frequency Division Multiplexing   OTT Over-the-Top   PCF Policy Control Function   PDC Physical Data Channel   PDCCH Physical Downlink Control Channel   P-GW Packet Data Network Gateway   PDSCH Physical Downlink Shared Channel   PUSCH Physical Uplink Shared Channel   QCL Quasi Co-Located   RAM Random Access Memory   RAN Radio Access Network   RB Resource Block   RE Resource Element   ROM Read Only Memory   RRC Radio Resource Control   RRH Remote Radio Head   RS Reference Signal   RV Redundancy Version   SCEF Service Capability Exposure Function   SCS Smaller Subcarrier Spacing   SINR Signal to Interference plus Noise Ratio   SLIV Start and Length Indicator Value   SMF Session Management Function   SPS Semi-Persistent Scheduling   TB Transport Block   TCI Transmission Configuration Indication   TDRA Time Domain Resource Allocation   TRP Transmission/Reception Points   TRS Tracking Reference Signal   UDM Unified Data Management   UE User Equipment   UL Uplink   UPF User Plane Function   URLLC Ultra-Reliable and Low Latency Communication       

     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.