Patent Publication Number: US-2022232595-A1

Title: Method of interlaced pucch design-format 1

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/IB2019/001269, filed on Oct. 5, 2019, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of communication technologies in unlicensed spectrum, and in particular, to a method for a user equipment to transmit a physical uplink control channel in a wireless communication system supporting an unlicensed band and apparatuses supporting the same. 
     The communication technology is for example a 5G (fifth generation) network using the 5G NR (New Radio) as radio access technology (RAT) defined by 3GPP. The present disclosure is applicable to 5G NR-U (NR in unlicensed spectrum). 
     BACKGROUND 
     According to the NR specification Release 15 (NR R15, 3GPP TS 38.213), the user equipment (UE) reports uplink control information (UCI) in a physical uplink control channel (PUCCH). 
     PUCCH Format 0 
     In NR Rel. 15, the PUCCH format 0 is generated from a specified computer generated sequence (CGS) of length 12, i.e., S(n),n=0, . . . , 11, which possesses very low 
     Peak-to-Average Power Ratio (PAPR) property. This channel can carry 1 or 2-bits ACK/NACK (A/N) information together with Scheduling Request (SR) indication. The A/N information is presented by the cyclic shift (CS), additionally introduced on top of the CGS. There are 12 possible CS, i.e. m=0, . . . , 11. The cyclic shifted sequence is given by 
     
       
         
           
             
               
                 
                   S 
                   
                     c 
                     ⁢ 
                     s 
                   
                 
                 ⁡ 
                 
                   ( 
                   n 
                   ) 
                 
               
               = 
               
                 
                   e 
                   
                     
                       
                         j 
                         ⁢ 
                         π 
                       
                       6 
                     
                     ⁢ 
                     α 
                     ⁢ 
                     n 
                   
                 
                 · 
                 
                   S 
                   ⁡ 
                   
                     ( 
                     n 
                     ) 
                   
                 
               
             
             , 
             
               n 
               = 
               0 
             
             , 
             
               . 
               
                   
               
               . 
               
                   
               
               . 
             
             ⁢ 
             
                 
             
             , 
             11 
             , 
           
         
       
     
     where α is a phase rotation depending on the selected CS m cs . The A/N information is tightly bounded with the m value, which is specified in NR Rel. 15, TS 38.213 section 9.2.3 and section 9.2.5.1. The PUCCH format 0 occupies 1 Physical Resource Block (PRB) in frequency (12 subcarriers) and 1 or 2 orthogonal frequency-division multiplexing (OFDM) symbols in time domain. 
     PUCCH Format 1 
     The PUCCH format 1 is an extension of format 0 in a way that the format 1 spreads the format 0 over multiple OFDM symbols (4 or more) as presented in NR Rel. 15, TS 38.213 section 9.2.2 and section 9.2.5.2. Moreover the DeModulation Reference Signals (DMRS) are alternated with the control sequence such as shown in  FIG. 2 , where one slot is used for a control signal and the next slot is used for a reference signal, etc. 
     NR-U PUCCH Interlace 
     In the unlicensed band in 5G Hz, the regulation imposes that if a transmitter wants to operate transmission in the channel, the transmission has to occupy at least 80% of the channel bandwidth. With this restriction in mind, NR-U decided to adopt an interlaced structure for two uplink channel transmissions, they are PUCCH and PUSCH. Each interlace structure will have specific number of PRB. Between each consecutive PRB pairs, there is M PRB further apart. For example, in a 20 Mhz bandwidth and for 30 Khz subcarrier spacing case, 1 interlace has 10 or 11 PRBs and M=5 as shown in  FIG. 1 . 
     The NR Rel.15 PUCCH format 1 occupies only 1 PRB in frequency domain, while in NR-U the interlaced structure has to be implemented. A simple repetition of NR Rel. 15 PUCCH format 1 in each of the PRBs of an interlace will cause very high PAPR issue. Thus, an enhancement should be done for this new design of PUCCH format 1 in NR-U systems. 
     SUMMARY 
     A first object of the present disclosure is a method of generating a physical uplink control channel (PUCCH) in unlicensed spectrum, which is transmitted by a user equipment, the method comprising:
     generating a PUCCH format 1 in an interlaced structure by:
       determining a cyclic shift group (CSG) containing a first cyclic shift member (CSMf) and a plurality of subsequent cyclic shift members (CSMn), each cyclic shift member (CSM) being defined at least by a value and a position, by:
           configuring the first cyclic shift member (CSMf) with a first indication related to the CSMf value and a second indication related to the CSMf position;   deriving the plurality of subsequent cyclic shift members (CSMn) based on the CSMf value and on the relative position between CSMf and each CSMn so as to define all CSM which are mutually different;   
           determining a first control sequence (S cs   i (n)), in one OFDM symbol within OFDM symbols allocated for control sequence, by a first base sequence (S(n)), an acknowledgment information symbol (b) and the cyclic shift group;   determining a first reference sequence (R cs   i (n)), in one OFDM symbol within all OFDM symbols allocated for reference sequence, by the first base sequence (S(n)) and the cyclic shift group.   
       

     Such method allows to generate a PUCCH format 1 in the interlaced structure that is able to carrier 1-bit, 2-bit A/N. Moreover this method allows to maintain a low PAPR property. The first and second indications may be assigned to different user equipments (UE) in order to enable UE multiplexing in the same resource, i.e. different UEs will be assigned to different first cyclic shift member, and/or different first cyclic shift member position. 
     Advantageously, the acknowledgment information (A/N) symbol is a complex-valued symbol (b), BPSK for 1-bit A/N or QPSK for 2-bit A/N. 
     Advantageously, the first control sequence is obtained by: 
     
       
         
           
             
               
                 
                   S 
                   
                     c 
                     ⁢ 
                     s 
                   
                   i 
                 
                 ⁡ 
                 
                   ( 
                   n 
                   ) 
                 
               
               = 
               
                 
                   e 
                   
                     
                       
                         j 
                         ⁢ 
                         π 
                       
                       6 
                     
                     ⁢ 
                     
                       m 
                       
                         c 
                         ⁢ 
                         s 
                       
                       i 
                     
                     ⁢ 
                     n 
                   
                 
                 · 
                 b 
                 · 
                 
                   S 
                   ⁡ 
                   
                     ( 
                     n 
                     ) 
                   
                 
               
             
             , 
           
         
       
     
     where S(n) is the base sequence and b is acknowledgment information (A/N) symbol. 
     Advantageously, the first reference sequence is obtained by: 
     
       
         
           
             
               
                 R 
                 
                   c 
                   ⁢ 
                   s 
                 
                 i 
               
               ⁡ 
               
                 ( 
                 n 
                 ) 
               
             
             = 
             
               
                 e 
                 
                   
                     
                       j 
                       ⁢ 
                       π 
                     
                     6 
                   
                   ⁢ 
                   
                     m 
                     
                       c 
                       ⁢ 
                       s 
                     
                     i 
                   
                   ⁢ 
                   n 
                 
               
               · 
               
                 
                   S 
                   ⁡ 
                   
                     ( 
                     n 
                     ) 
                   
                 
                 . 
               
             
           
         
       
     
     Advantageously, the cyclic shift group (CSG) includes Scheduling Request (SR) information. 
     Such method allows to design a PUCCH format 1 including the SR indication which can be used to obtain mutually different CSM. 
     Advantageously, the method comprises:
         spreading the first control sequence (S cs   i (n)) over the OFDM symbols allocated for control sequence; and   spreading the first reference sequence (R cs   i (n)) over the OFDM symbols allocated for reference sequence.       

     Advantageously, the first control sequence spreading is given by: 
         S   cs   i,j ( n )= S   cs   i ( n )· w ( j ),
 
     where w(j) is a first orthogonal sequence and for which the generated PUCCH format 1 contains m OFDM symbols for the first control sequence spreading; 
     and wherein first reference sequence spreading is given by: 
         R   cs ( n )= R   cs   i ( n )· w ′ ( j ),
 
     where w′(j) is the second orthogonal sequence and for which the generated PUCCH format 1 contains l OFDM symbols for the first reference sequence spreading. 
     Advantageously, the first indication is either a direct indication of the CSMf value from a set of CSM candidates or an indirect indication by a first offset with respect to a reference value of the CSMf in a set of ordered CSM candidates. More preferably, in case of an indirect indication, the reference value of the CSMf is either pre-defined or configured via a radio resource control (RRC) or derived by a first function. Advantageously, a default CSMf value is set in the absence of a first indication. 
     Such first indication (direct, indirect or by default) allows to determine the value of CSMf and derive the subsequent values of CSMn. 
     Advantageously, the second indication is either a direct indication of the CSMf position in the CSG from a set of position candidates or an indirect indication by a second offset with respect to a reference position of the CSMf in a set of ordered position candidates. More preferably, in case of an indirect indication, the reference position of the CSMf is either pre-defined or configured via a radio resource control (RRC) or derived by a second function. Advantageously, a default CSMf position is set in the absence of a second indication. 
     Such second indication (direct, indirect or by default) allows to determine the position of CSMf and derive the subsequent position of CSMn. 
     Advantageously, subsequent CSMn values are derived using a third function including at least one parameter T determined by a third indication. More preferably, the third indication is either a direct indication of the parameter value from a set of parameter value candidates or a default value in the absence of the third indication. 
     The first, second and third indications may be assigned to different UEs in order to enable UE multiplexing in the same resource, i.e. different UEs will be assigned to different first cyclic shift member, and/or different first cyclic shift member position, and/or different T. Thus, the third indication allows to further reduce the PAPR issues. 
     Advantageously, the plurality of subsequent cyclic shift members (CSMn) is derived in a way such that CSMn and the CSMf have the following relationship: 
         m   cs   j =( m   cs   i +(( j−i )mod  N   RB   interlace ) T )mod 12. 
     A second object of the present disclosure is a user equipment transmitting a physical uplink control channel to a base station in a wireless communication system in unlicensed spectrum, the user equipment comprising: 
     a processor configured to generate a PUCCH format 1 in an interlaced structure by:
         determining a cyclic shift group (CSG) containing a first cyclic shift member (CSMf) and a plurality of subsequent cyclic shift members (CSMn), each cyclic shift member (CSM) being defined at least by a value and a position, by:
           configuring the first cyclic shift member (CSMf) with a first indication related to the CSMf value and a second indication related to the CSMf position;   deriving the plurality of subsequent cyclic shift members (CSMn) based on the CSMf value and on the relative position between CSMf and each CSMn so as to define all CSM which are mutually different;   
           determining a first control sequence (S cs   i (n)), in one OFDM symbol within OFDM symbols allocated for control sequence, by a first base sequence (S(n)), an acknowledgment information symbol (b) and the cyclic shift group;   determining a first reference sequence (R cs   i (n)), in one OFDM symbol within all OFDM symbols allocated for reference sequence, by the first base sequence (S(n)) and the cyclic shift group.       

     Advantageously, the processor is configured to generate the PUCCH format 1 according to any of the advantageous aspects of the first object. 
     A third object of the present disclosure is a computer readable medium comprising program instructions for causing a user equipment to perform the steps of the transmitting method according to the first object. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The appended drawings required in description of embodiments or the prior art will be briefly described below. 
         FIG. 1  shows an example of an interlaced structure for PUCCH; 
         FIG. 2  shows an example of reference signal alternated with a control signal; 
         FIG. 3  shows an example of a cyclic shift group (CSG) within 1 interlace; 
         FIG. 4  shows another example of a cyclic shift group (CSG) within 1 interlace; 
         FIG. 5  shows another example of a cyclic shift group (CSG) within 1 interlace; 
         FIG. 6  shows another example of a cyclic shift group (CSG) within 1 interlace; 
         FIG. 7  shows another example of a cyclic shift group (CSG) within 1 interlace. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following disclosure, we will first present a cycle shift group and cycle shift member, followed by examples for implementing a method of generating a PUCCH format 1. 
     Cycle Shift Group and Cycle Shift Members 
     The cyclic shift group (CSG) can be expressed as m cs   i  with i= 0 , . . . , N RB   interlace −1, where N RB   interlace  stands for the total number of PRB within 1 interlace; m cs   i  is a cyclic shift member and its corresponding position is i-th position within the cyclic shift group. Thus a cyclic shift group contains N RB   interlace  cyclic shift members and accordingly it contains N RB   interlace  positions. In the example of  FIG. 3 , we assume N RB   interlace =10. Therefore, the position i goes from 0 up to 9. 
     If one cyclic shift member as well as its position are determined (i.e. m cs   i ), the cyclic shift member on the rest of the positions (i.e. m cs   j ) can be derived from some pre-defined relationship, such as: 
         m   cs   j =( m   cs   i +(( j−i )mod  N   RB   interlace ) T )mod 12. 
     In this example, all cyclic shift members on j-th position, m cs   j , can be derived from m c   i   s  and the relative position between j and i, and optionally with a parameter T. Here m cs   i  is the value of the so-called first cycle shift member (CSMf), to be indicated by a first indication, i is the position of CSMf, to be indicated by a second indication, and T is an optional first parameter to be indicated by a third indication. 
     Cycle Shift Member Candidates and Generation of PUCCH Format 1 
     In the present disclosure, we assume that the cyclic shift member (CSM) can take the value from a set of candidate values, called cyclic shift member candidates. The candidate values are integer values from 0 up to 11, i.e. {0,1,2,3,4,5,6,7,8,9,10,11}. The re a son of this choice is that after the cyclic shift group is decided, the PUCCH format 1 is generated as follows. 
     In this example, the reference parameters m cs   ref , p ref , t ref , have a fixed or configured initial values. Thus, when the UE receives the offset 1 , offset 2 , offset 3 , the UE can obtain the first control sequence such as: 
     
       
         
           
             
               
                 
                   S 
                   
                     c 
                     ⁢ 
                     s 
                   
                   i 
                 
                 ⁡ 
                 
                   ( 
                   n 
                   ) 
                 
               
               = 
               
                 
                   e 
                   
                     
                       
                         j 
                         ⁢ 
                         π 
                       
                       6 
                     
                     ⁢ 
                     
                       m 
                       
                         c 
                         ⁢ 
                         s 
                       
                       i 
                     
                     ⁢ 
                     n 
                   
                 
                 · 
                 b 
                 · 
                 
                   S 
                   ⁡ 
                   
                     ( 
                     n 
                     ) 
                   
                 
               
             
             , 
             
               n 
               = 
               0 
             
             , 
             
               . 
               
                   
               
               . 
               
                   
               
               . 
             
             ⁢ 
             
                 
             
             , 
             
               11 
               ; 
               
                 i 
                 = 
                 0 
               
             
             , 
             
               . 
               
                   
               
               . 
               
                   
               
               . 
             
             ⁢ 
             
                 
             
             , 
             
               
                 N 
                 
                   R 
                   ⁢ 
                   B 
                 
                 interlace 
               
               - 
               1 
             
             , 
           
         
       
     
     where S(n) is a base sequence and b is a complex-valued symbol, BPSK for 1-bit A/N or QPSK for 2-bit A/N. 
     Then, the first control sequence spreading is given by: 
         S   cs   i,j ( n )= S   cs   i ( n )· w ( j ),  n= 0, . . . , 11;  i= 0, . . . ,  N   RB   interlace −1, j= 0, . . .  m− 1,
 
     where, w(j) is the first orthogonal sequence and we assume that have a PUCCH format 1 which contains m OFDM symbols for first control sequence spreading. 
     The first reference sequence is obtained by: 
     
       
         
           
             
               
                 
                   R 
                   
                     c 
                     ⁢ 
                     s 
                   
                   i 
                 
                 ⁡ 
                 
                   ( 
                   n 
                   ) 
                 
               
               = 
               
                 
                   e 
                   
                     
                       
                         j 
                         ⁢ 
                         π 
                       
                       6 
                     
                     ⁢ 
                     
                       m 
                       
                         c 
                         ⁢ 
                         s 
                       
                       i 
                     
                     ⁢ 
                     n 
                   
                 
                 · 
                 
                   S 
                   ⁡ 
                   
                     ( 
                     n 
                     ) 
                   
                 
               
             
             , 
             
               n 
               = 
               0 
             
             , 
             
               . 
               
                   
               
               . 
               
                   
               
               . 
             
             ⁢ 
             
                 
             
             , 
             
               11 
               ; 
               
                 i 
                 = 
                 0 
               
             
             , 
             
               . 
               
                   
               
               . 
               
                   
               
               . 
             
             ⁢ 
             
                 
             
             , 
             
               
                 N 
                 
                   R 
                   ⁢ 
                   B 
                 
                 interlace 
               
               - 
               
                 1 
                 . 
               
             
           
         
       
     
     Then the first reference sequence spreading is: 
         R   cs   i,j ( n )= R   cs   i ( n )· w ′( j ),  n= 0, . . . , 11 ; i= 0 , . . . , N   RB   interlace −1,  j= 0, . . .  l− 1
 
     where, w′(j) is the second orthogonal sequence and we assume that have a PUCCH format 1 which contains l OFDM symbols for first reference sequence spreading. 
     Examples of Determination of the Cycle Shift Group 
     For example, if we assume that N RB   interlace =10, and T=1, when one cyclic shift member (CSM) value and its corresponding position is given, for example m cs   0 =0 , then we can derive m cs   j =(0+j mod 10)mod 12={1,2,3,4,5,6,7,8,9} for j={1,2,3,4,5,6,7,8,9}, respectively. Thus, the cyclic shift group CSG is m cs   i =i, for i={0,1,2,3,4,5,6,7,8,9} as shown in  FIG. 4 . 
     In this example, the first cyclic shift member CSMf (a.k.a. m cs ), for which the cyclic shift member value is indicated by the first indication and its position is indicated by the second indication, i.e. m cs   0 =0. The rest of the cyclic shift members (CSMn) in the group can be derived from a pre-defined relationship, which is m cs   j =(m cs   0 +((j−0)mod 10)T)mod 12. Then the third indication will give the value of the parameter T, i.e. T=1 in our example. 
     Another example, if we set one cyclic shift member and its corresponding position to m cs   5 =0, then we can derive m cs   j =(0+(j−5)mod 10)mod 12={5,6,7,8,9,1,2,3,4} for j={0,1,2,3,4,6,7,8,9}, respectively. Thus, the cyclic shift group is {5,6,7,8,9,0,1,2,3,4} as shown in  FIG. 5 . 
     In this example, the first cyclic shift member CSMf (a.k.a. m cs ), for which the cyclic shift member value is indicated by the first indication and its position is indicated by the second indication, i.e. m cs   5 =0. The rest of the cyclic shift members in the group can be derived from a pre-defined relationship, which is m cs   j =(m cs   5 ((j−5)mod 10)T)mod 12. Then the third indication will give the value of the parameter T, i.e. T=1 in our example. 
     CSG Determination with Offset Indications 
     Coming back to the CSG determination, the network, e.g. a base station, can send the first and second indications to inform the UE about the first cyclic shift member and its corresponding position. For example, the first indication can be an offset w.r.t. m cs   ref , e.g. offset 1 =2; and the second indication can point directly to the position index, such as 5. In this manner, the UE knows that the first cyclic shift member is m cs   5 =m cs   ref +offset 1 =2. 
     As long as the first cyclic shift member is determined, all the subsequent members can be derived from it when the derivation relationship is determined, which can be optionally depending on a the third indication. Assume that the third indication points the parameter T=1, then we have the following derivation relationship: 
         m   cs   j =( m   cs   5 +(( j− 5)mod 10))mod 12. 
     As a result the cycle shift group determined is given in  FIG. 6 . 
     It is worth noting that the second and the third indications can also indicate an offset w.r.t. a pre-defined reference. For instance, for the second indication, the network can define a reference position, e.g., p ref =0, then the indication gives an offset . Thus, the UE will understand that the indicated position is p=p ref +offset 2 , where offset 2 ={ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 }. 
     Similarly, the third indication can also give an offset 3  within a set of candidate values w.r.t. a pre-defined value, e.g. T=A (t ref +offset 3 ). Assuming the candidate values are {1,3,5,7,11} and t ref =0. Then the third indication can indicate: offset 3 ={0,1,2,3,4}. Either ways, i.e. direct indication or indirect indication via reference and offsets, will lead to the same cyclic shift group. 
     Examples of CSG with Scheduling Request (SR) 
     In a more complex example, the UE has to report positive SR or negative SR. The reference cyclic shift member value can be used to reflect positive and negative SR. An example is shown in  FIG. 7  where reference values are pre-defined: 
     positive SR: m cs   i =k, where i={0,1,2,3,4} and k={7,8,9,10,11}; 
     negative SR: m cs   i =k, where i={5,6,7,8,9} and k={2,3,4,5,6}. 
     Alternatively, to include SR, we can also set the reference cyclic shift member value m cs   ref  and/or the reference position p ref  and/or the reference parameter t ref  to represent SR. For example, p ref =0 is used for a positive SR and p ref =5 is used for a negative SR. Another example, t ref =1 is used for a positive SR and t ref =7 is used for a negative SR. Another example, m cs   ref =0 is used for a positive SR and m cs   ref =6 is used for a negative SR. Any combination is also possible. 
     Example of UE Multiplexing 
     In the above examples, the reference cyclic shift member, m cs   ref , may represent SR results, while the first, second and third indications are assigned to different UEs in order to enable UE multiplexing in the same resource, i.e. different UEs will be assigned to different first cyclic shift member, and/or different first cyclic shift member position, and/or different T. 
     LIST OF ABBREVIATIONS IN THE DESCRIPTION AND DRAWINGS 
       
     
       
         
           
               
               
             
               
                   
               
               
                 Acronyms 
                 Full name 
               
               
                   
               
             
            
               
                 LTE 
                 Long Term Evolution 
               
               
                 LTE-A 
                 Advanced long term evolution 
               
               
                 NR 
                 New Radio 
               
               
                 NR-U 
                 New Radio-unlicensed 
               
               
                 BS 
                 Base-station 
               
               
                 UE 
                 User Equipment 
               
               
                 PUCCH 
                 Physical Uplink Control CHannel 
               
               
                 PUSCH 
                 Physical Uplink Shared CHannel 
               
               
                 UCI 
                 UPlink control information 
               
               
                 LBT 
                 Listen Before Talk 
               
               
                 SR 
                 Scheduling Request 
               
               
                 CSM 
                 Cyclic Shift Member 
               
               
                 CSMf 
                 first Cyclic Shift Member 
               
               
                 CSMn 
                 subsequent Cyclic Shift Member 
               
               
                 CSG 
                 Cyclic Shift Group 
               
               
                 A/N 
                 ACK/NACK (Acknowledgment/Non-Acknowledgment) 
               
               
                 OFDM 
                 Orthogonal frequency-division multiplexing 
               
               
                   
               
            
           
         
       
     
     In the above description, the mobile telecommunication system is a 5G mobile network comprising a 5G NR access network. The present example embodiment is applicable to NR in unlicensed spectrum (NR-U). The present disclosure can be applied to other mobile networks, in particular to mobile network of any further generation cellular network technology (6G, etc.). 
     The above is only a specific implementation manner of the present disclosure, the protection scope of the present disclosure is not limited thereto, and changes or substitutions that can easily be thought of by those skilled in the art within the technical scope disclosed in the present disclosure should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims. 
     The various embodiments/examples, aspects and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.