Technical Field

[0001] 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.

[0002] 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

[0003] According to the NR specification Release 15 (NR R15, 3GPP TS 38.213), the UE reports uplink control information (UCI) in a physical uplink control channel (PUCCH).

[0004] PUCCH format 0

[0005] 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 carrier 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 _cs = 0, The cyclic shifted sequence is given by where a is a phase rotation depending on the selected CS m _cs . The A/N information is tightly bounded with the m _cs 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.

[0006] NR-U PUCCH interlace

[0007] 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 20Mhz bandwidth and for 30Khz subcarrier spacing case, 1 interlace has 10 or 11 PRBs and M = 5 as shown in Figure 1.

[0008] The NR Rel.15 PUCCFI format 0 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 PUCCFI format 0 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 PUCCFI format 0 in NR-U systems.

Summary

[0009] A first object of the present disclosure is a method of transmitting a physical uplink control channel (PUCCFI) in unlicensed spectrum, which is transmitted by a user equipment, the method comprising:

- generating a PUCCFI format 0 in an interlaced structure, based on a base sequence (BSEQ), an acknowledgment information (A/N), and a cyclic shift group (CSG) containing a number of cyclic shift members (CSM) corresponding to the resource block number within the interlaced structure;

- determining the 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 by a value and a position, by: o 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; o 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;

- defining a one-to one mapping relationship between the CSG and an acknowledgment information (A/N);

- transmitting the generated PUCCFI using format 0.

[0010] Such method allows to generate and transmit a PUCCFI format 0 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 PAPR reduction is due to the cyclic shift group under the condition that the cyclic shift members are mutually different. The relationship between the different cyclic shift members ensures this condition. 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. The one-to-one mapping definition is done so that for the same UE with the same first and second indications, different A/N statuses will relate to different CSG and for different UEs with different indications, each A/N status will relate to different CSG.

[0011] Advantageously, the PUCCH using format 0 generation comprises the acknowledgement information (A/N) together with a Scheduling Request (SR) indication and the one-to-one mapping relationship definition is done between the CSG and the A/N information together with the SR indication.

[0012] Such method allows to design a PUCCH format 0 including the SR indication which can be used to obtain mutually different CSM. Further, the one-to- one mapping definition will be extended to SR so that for the same UE with the same indications, different A/N+SR statuses will relate to different CSG and for different UEs with different indications, each A/N+SR status will relate to different CSG.

[0013] 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 resrouce control (RRC) or derived by a first function. Advantageously, a default CSMf value is set in the absence of a first indication.

[0014] Such first indication (direct, indirect or by default) allows to determine the value of CSMf and derive the subsequent values of CSMn.

[0015] 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 resrouce control (RRC) or derived by a second function. Advantageously, a default CSMf position is set in the absence of a second indication. [0016] Such second indication (direct, indirect or by default) allows to determine the position of CSMf and derive the subsequent position of CSMn.

[0017] 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.

[0018] 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. The one-to-one mapping definition will be extended so that for the same UE with the same first, second and third indications, different A/N or A/N+SR statuses will relate to different CSG and for different UEs with different indications, each A/N or A/N+SR status will relate to different CSG.

[0019] 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: o generate a PUCCH format 0 in an interlaced structure, based on a base sequence (BSEQ), an acknowledgment information (A/N), and a cyclic shift group (CSG) containing a number of cyclic shift members (CSM) corresponding to the resource block number within the interlaced structure; o determine 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 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; o define a one-to one mapping relationship between CSG and an acknowledgment information (A/N); and

- a transmitter to transmit the generated PUCCH.

[0020] Advantageously, the processor is configured to generate the PUCCH using format 0 comprising the acknowledgement information (A/N) together with a Scheduling Request (SR) indication; and to define the one-to-one mapping relationship between the CSG and the A/N information together with the SR indication.

[0021] 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 resrouce control (RRC) or derived by a first function. Advantageously, the process is configured to set a default CSMf value in the absence of a first indication.

[0022] 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 resrouce control (RRC) or derived by a second function. Advantageously, the process is configured to set a default CSMf position in the absence of a second indication.

[0023] Advantageously, the process is configured to derive subsequent CSMn values 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.

[0024] 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 aspect.

Brief description of the drawings

[0025] 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 a cyclic shift group (CSG) within 1 interlace ;

- Fig. 3 shows another 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. 5A-5B shows an example of 1-bit and 2-bit ACK/NACK reporting using a determined cyclic shift group (CSG);

- Fig. 6A-6B shows an example of ACK and NACK reporting using a determined

CSG;

- Fig. 7A-7B shows an example of 1-bit and 2-bit ACK/NACK with Scheduling

Request (SR) reporting using a determined CSG;

- Fig. 8 shows another example of 1-bit ACK/NACK reporting using a determined

CSG with several references.

Description of embodiments

[0026] In the following disclosure, we will first present a cycle shift group and cycle shift member, followed by examples for implementing to method of generating and transmitting a PUCCH format 0.

[0027] Cycle shift group and cycle shift members

[0028] The cyclic shift group (CSG) can be expressed as stands for the total number of PRB within 1 interlace; is a cyclic shift member and its corresponding position is i-th position within the cyclic shift group. Thus a cyclic shift group contains cyclic shift members and accordingly it contains positions. In the example of figure 2, we assume Therefore, the position i goes from 0 up to 9.

[0029] If one cyclic shift member as well as its position are determined (i.e. the cyclic shift member on the rest of the positions can be derived from some pre-defined relationship, such as:

[0030] In this example, all cyclic shift members on j-th position, can be derived from and the relative position between j and i, and optionally with a parameter T. Here m 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. [0031] Cycle shift member candidates

[0032] 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 reason of this choice is that after the cyclic shift group is decided, the PUCCH format 0 is formed as where α(i) is i-th phase rotation that is a function of the i-th cyclic shift member .

In the following we simply write it as · S(n ). Note that S(n) is a base sequence for PUCCH format 0.

[0033] Examples of determination of the cycle shift group

[0034] For example, if we assume that , and T=1, when one cyclic shift member (CSM) value and its corresponding position is given, for example , then we can derive for j={1,2,3,4,5,6,7,8,9}, respectively. Thus, the cyclic shift group CSG is for j={0, 1,2, 3, 4, 5, 6, 7, 8, 9} as shown in Figure 3.

[0035] 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. The rest of the cyclic shift members (CSMn) in the group can be derived from a pre-defined relationship, which is Then the third indication will give the value of the parameter T, i.e. T=1 in our example.

[0036] Another example, if we set one cyclic shift member and its corresponding position to , then we can derive 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 hown in Figure 4. [0037] 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. The rest of the cyclic shift members in the group can be derived from a pre-defined relationship, which is Then the third indication will give the value of the parameter T, i.e. T=1 in our example.

[0038] Examples of ACK/NACK only with 1 or 2 bits

[0039] The user equipment (UE) reports ACK/NACK (A/N) using the determined cyclic shift group (CSG). In this example, we assume that there is a 5 reference value for the first cyclic shift member CSMf, which can be p re-specified, such as for the case of 1-bit A/N, for NACK as shown in Figure 5A. Thus in this example, when a UE has to report 1-bit A/N, if the A/N=ACK, the reference cyclic shift member value is 0, and if the A/N=NACK, the reference cyclic shift member is 6.

10 [0040] For the case of 2-bits A/N, four reference values are pre-defined : as shown in Figure 5B.

[0041] Thus in this example, when a UE has to report 2-bit A/N, if 15 - the A/N= [0, 0] ACK, the reference cyclic shift member value is 0,

- the A/N= [0, 1] ACK, the reference cyclic shift member value is 3,

- the A/N= [1 , 1] NACK, the reference cyclic shift member is 6, and

- the A/N= [1 , 0] NACK, the reference cyclic shift member is 9.

[0042] Alternatively, it can be defined that each even slot is for ACK and each 20 odd slot is for NACK.

[0043] Coming back to the 1-bit A/N example shown in Figure 5A, 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. e.g. offset ₁ = 2; and the second indication can 25 point directly to the position index, such as 5. In this manner, the UE knows that the

- first- cyclic shift- member -is - for ACK; and = 8 for NACK.

[0044] As long as the first cyclic shift member is determined, all the subsequent members can be derived from it when the derivation relationship is 30 determined, which can be optionnaly depending on a the third indication. Assume that the third indication points the parameter T=1 , then we have the following derivation relatinship : [0045] As a result the cycle shift group determined for ACK is given in Figure 6A and the cycle shift group determined for NACK is given in Figure 6B.

[0046] 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 offset2 . 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}.

[0047] 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. Assuming the candidate values are {1 ,3,5,7,11} and 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 for A/N reporting.

[0048] Examples of ACK/NACK together with Scheduling Request (SR)

[0049] In a more complex example, the UE has to report A/N together with positive SR or negative SR. Similar to the example with A/N only, the reference cyclic shift member value can be used to reflect different combinations of A/N+SR. An example for 1-bit A/N + SR case is shown in Figure 7A and another example for 2-bit A/N + SR is shown in Figure 7B.

[0050] Thus in Figure 7A, for the case of 1-bit A/N+SR, four reference values are pre-defined :

[0051] In Figure 7B, for the case of 1-bit A/N+SR, eight reference values are pre-defined :

[0052] Then the rest of the process is similar to the ACK/NACK only with 1 or 2 bits.

[0053] Example of reference to A/N mapping and UE multiplexing [0054] In the above examples, the reference cyclic shift member, represents the A/N or A/N+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.

[0055] It is worth noting that other options are possible, such that selecting to represent A/N or A/N+SR. An example for 1-bit A/N is shown in Figure 8. It is to say that we have three different references, i.e. so normally any reference or any combination of multiple references can be used to represent A/N or A/N+SR.

[0056] List of abbreviations in the description and drawings:

[0057] 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.).

[0058] 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.

[0059] 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.