Patent Description:
Mobile telecommunication technologies are moving the world toward an increasingly connected and networked society. In comparison with the existing wireless networks, next generation systems and wireless communication techniques will need to support a much wider range of use-case characteristics and provide a more complex and sophisticated range of access requirements and flexibilities.

Long-Term Evolution (LTE) is a standard for wireless communication for mobile devices and data terminals developed by 3rd Generation Partnership Project (3GPP). LTE Advanced (LTE-A) is a wireless communication standard that enhances the LTE standard. The 5th generation of wireless system, known as <NUM>, advances the LTE and LTE-A wireless standards and is committed to supporting higher data-rates, large number of connections, ultra-low latency, high reliability and other emerging business needs.

<NPL> and <NPL> are related prior art documents.

This disclosure relates to methods, apparatuses and non-transitory computer readable program storage mediums for grouping and using short sequences in wireless communications, such as Physical Uplink Control Channel (PUCCH) and/or short PUCCH transmissions.

In the 4th Generation (<NUM>) mobile communication technology of LTE/LTE-A and the 5th Generation (<NUM>) mobile communication technology, more complex and sophisticated range of access requirements and flexibilities are provided or being developed. Currently, enhanced mobile broadband (eMBB), ultra high reliability and low latency communication (URLLC), and massive machine type communications (mMTC) are under study and/or in development for both <NUM> and <NUM> systems.

New Radio (NR) technology, currently under standardization in <NUM>, has proposed the use of short PUCCH transmissions. More specifically, this disclosure relates to the grouping and use of new short sequences that are orthogonal and meet performance requirements of the short PUCCH under consideration in the 3GPP standards organization.

The PUCCH or short PUCCH is a wireless channel used to transmit information from mobile stations or user equipment (UE) to a base station. For example, the UE may use the PUCCH to transmit information such as an Acknowledgement (ACK), Non-Acknowledgement (NACK), and scheduling request (SR). The UE can transmit ACK/NACK to the base station to inform the base station whether the UE has properly decoded the data transmitted by the base station. A scheduling request (SR) is used by the UE to request uplink resources to transmit data.

In the standardization of NR, it has been agreed that sequences with low peak to average power ratio (PAPR) be adopted for short PUCCH to carry up to <NUM> bits of uplink control information (UCI). In comparison, LTE adopted computer generated constant amplitude zero auto correlation (CG-CAZAC) sequences with lengths of <NUM> and <NUM> for <NUM> or <NUM> resource blocks (RBs) and adopted cyclic extension of Zad-off Chu (ZC) sequences for <NUM> or more RBs. The NR sequence requirements are more stringent (e.g., requiring a lower cubic metric/peak to average power ratio (CM/PAPR)). The length-<NUM>, length-<NUM>, and length-<NUM> sequences currently used in LTE may not satisfy these new requirements. Therefore, new sequences with low CM/PAPR have been proposed. In the 3GPP RANI 90bis meeting, a set of <NUM> length-<NUM> base sequences for short PUCCH has been adopted for NR. The set of length-<NUM> sequences can be expressed as: <MAT> where ϕ(n) is listed in Table-<NUM> below.

And in the 3GPP RAN1 <NUM> meeting, a set of <NUM> length-<NUM> and a set of <NUM> length-<NUM> base sequences have also been adopted for NR. The set of length-<NUM> sequences can be expressed as: <MAT> where ϕ(n) is listed in Table-<NUM> below.

The set of length-<NUM> sequences can be expressed as: <MAT> where ϕ(n) is listed in Table-<NUM> below.

In LTE, uplink sequences are grouped into multiple sequence groups for use in wireless communications. For example, each sequence group can include at least two sequences of different lengths, and different sequence groups can be allocated for use by different cells. In NR, similar sequence grouping and allocation can be adopted. As discussed above, new length-<NUM>, length-<NUM>, and length-<NUM> sequences have been introduced in NR. Therefore, sequence grouping and allocation for the newly introduced NR sequences is desired. The presently disclosed technology addresses the grouping of the length-<NUM>, length-<NUM>, and length-<NUM> sequences adopted in NR with other sequences (e.g., certain sequences currently used in LTE), and the use of the newly configured sequence groups in wireless communications.

<FIG> shows an exemplary base station and UEs in wireless communications that use PUCCH and/or short PUCCH channels. The base station (<NUM>) can transmit channel resources allocated to the plurality of UEs (110a-110c). The UEs (110a-110c) can transmit information using allocated sequences via PUCCH and/or short PUCCH channels (130a-130c) to the base station (<NUM>). The presently disclosed technology provides various embodiments of sequence grouping and use in wireless communications between the base station and the UEs.

When sequences are used for wireless communications, signal interference between different cells can depend on the correlation between the sequences used. In order to minimize inter-cell interference, it is desirable to have low correlations between sequences used by different cells. In other words, it is desirable to have high cross-correlations between sequences of different lengths that are included in a same group. Accordingly, in some embodiments, the presently disclosed technology includes allocating into a same sequence group sequences that (<NUM>) have different lengths and (<NUM>) have high cross-correlations between or among themselves. In allocating the newly introduced NR sequences into existing LTE sequence groups, the presently disclosed technology accounts for cross-correlations between these newly introduced sequences and the existing LTE sequences.

<FIG> shows an exemplary flowchart of a method for allocating new sequences (e.g., the newly introduced length-<NUM>, length-<NUM>, or length-<NUM> NR sequences) into existing sequence groups (e.g., sequence groups currently used in LTE), in accordance with some embodiments of the presently disclosed technology. For purposes of illustration, the newly generated NR sequences that are being allocated are denoted by S<NUM>,i , where i represents a sequence index selected from <NUM>, <NUM>, <NUM>,. , <NUM> and the value of S<NUM>,i can be found in Table-<NUM>, Table-<NUM>, or Table-<NUM> above. Other sequences of length-Y (e.g., currently used in LTE) are denoted by S<NUM>,u, wherein Y can be <NUM>,<NUM>,<NUM> or other multiples of <NUM> and specific S<NUM>,u values can be found in TS36. The sequences of S<NUM>,u belong to <NUM> sequence groups, where u represents a sequence group index selected from <NUM>, <NUM>, <NUM>,.

Because there are <NUM> new sets of sequences introduced in NR, in some embodiments, the allocation involves all <NUM> new sets of NR sequences. For example, the allocation of new length-<NUM> NR sequences can be performed first. When allocating the new length-<NUM> sequences, the existing LTE sequences of length-<NUM>,<NUM>, <NUM>, or other multiples of <NUM> can be used as references for cross correlation calculation. After completing the sequence allocation for the new length-<NUM> sequences, allocation of new length-<NUM> sequences can be performed. When allocating the new length-<NUM> sequences, both (<NUM>) the new length-<NUM> sequences after re-grouping (i.e., the new length-<NUM> sequences as allocated into the existing sequence groups) and (<NUM>) the exiting LTE sequences of length-<NUM>,<NUM>,<NUM> or other multiples of <NUM> can be used as references for cross correlation calculation. A similar process can be applied to the allocation of the new length-<NUM> sequences. Illustratively, the new length-<NUM> sequences and new length-<NUM> sequences after re-grouping as well as the exiting LTE sequences of length-<NUM>,<NUM>,<NUM> or other multiples of <NUM> can be used as references for length-<NUM> sequences allocation.

With reference to <FIG>, at block <NUM>, the method includes determining correlations between each new sequence and sequence(s) included in each existing sequence groups. Illustratively, the method includes computing cross correlations between each of the <NUM><NUM>,i sequences and the S<NUM>,u sequence included in each of the <NUM> sequence groups. The cross correlation values can be represented in a cross correlation matrix XCORRi,u, where each row corresponds to an individual new sequence S<NUM>,i and each column corresponds to a sequence S<NUM>,u included in an individual sequence group (of group index u).

In various embodiments, cross correlations between the new NR sequence and other existing length-Y base sequences can be calculated. The existing length-Y base sequences used in LTE with Y>=<NUM> can be expressed as: <MAT> where the qth root Zadoff-Chu sequence is defined by <MAT> with q given by <MAT> <MAT>.

The length <MAT> of the Zadoff-Chu sequence is given by the largest prime number such that <MAT> where <MAT>, and v=<NUM> or <NUM> when Y>=<NUM>.

The cross correlation between two sequences can be calculated based on the following equation: <MAT> where IFFT(X, N) is the N_point Inverse Fourier Transform operation, Seql and Seq2 denote the two sequences, conj() is the complex conjugate operation.

In cases where the length of Seql and Seq2 are unequal, zeros padding can be applied to the shorter sequence when performing Seql. * conj(Seq2) for all possible frequency positions. <FIG> show two examples of zeros padding application, in accordance with some embodiments of the presently disclosed technology. Seql is the sequence of shorter length when using Eq.<NUM> for cross correlation calculation.

In various embodiments, a sequence group includes sequences of different lengths. In some embodiments, the cross correlation between the new NR sequences and existing sequences of all other lengths can be evaluated. In some embodiments, however, the number of the existing sequences of different lengths can be too large. For example, Y can be equal to 12N with N ranging from <NUM> to <NUM>. Given limited computation resources, it can be impractical to calculate the cross correlation between the new NR sequences and all the existing sequences. Therefore, in some embodiments, only a selected subset of existing sequences lengths are considered when allocating the new sequences into sequences group. For example, existing sequences of length-<NUM>, length-<NUM>, length-<NUM>, and length-<NUM> are selected as a basis for the new NR sequences allocations.

More specifically, in some embodiments, when allocating the new length-<NUM> sequences, the existing sequences with lengths <NUM>,<NUM>,<NUM> and <NUM> are used. Among which, the cross correlation between the new length-<NUM> sequences and the existing length-<NUM> sequences takes first priority in the sequence allocation process. This is at least partly because the length-<NUM> sequences were used as reference sequences for grouping sequences of other lengths when forming the LTE sequence groups.

When allocating the new length-<NUM> sequences, the existing sequences with lengths <NUM>,<NUM>,<NUM>,<NUM> and the new length-<NUM> sequences (after re-grouping) are used. Among which, the cross correlation between the new length-<NUM> sequences and the existing length-<NUM> sequences takes first priority in the sequence allocation process. Compared with the lengh-<NUM> sequences, cross correlations between the new length-<NUM> sequences and sequences of other lengths have lower priorities. In some embodiments, other than the length-<NUM> sequences that correspond to the highest priority, the cross correlation with sequences of a shorter length has a higher priority than with sequences of a longer length. For example, the cross correlation between the new length-<NUM> sequences and the new length-<NUM> sequences (after regrouping) has a higher priority than the cross correlation between the new length-<NUM> sequences and the existing length-<NUM> sequences.

Similarly, when allocating the new length-<NUM> sequences, the existing sequences with lengths <NUM>,<NUM>,<NUM>, <NUM>, the new length-<NUM> sequences (after regrouping), and the new length-<NUM> sequences (after re-grouping) are used. Among which, the cross correlation with the existing length-<NUM> sequences takes first priority in the sequence allocation process. Then starting from the new length-<NUM> sequences (after regrouping), cross correlations with sequences of increasing lengths take decreasing priorities in the sequence allocation process. That is , cross correlation with the new length-<NUM> sequences (after regrouping) takes second priority, cross correlation with the new length-<NUM> sequences (after regrouping) takes third priority, and so on.

With reference to <FIG>, at block <NUM>, the method includes allocating one or more new sequences to existing sequence groups based on condition(s) on corresponding correlations. Illustratively, cross correlation values that exceed certain threshold or are relatively large can serve as bases for allocating new sequences to existing groups. In some embodiments, for each new NR sequence S<NUM>,i, the method includes identifying the maximum cross correlation value within a corresponding row of the cross correlation matrix XCORRi,u. A group index u = umax(i) that corresponds to the identified maximum cross correlation value is selected, and the new NR sequence S<NUM>,i is allocated to existing sequence group of index umax(i).

In cases where a same group index umax(i) is selected for multiple S<NUM>,i's, their corresponding cross correlation values XCORRi,umax(i)'s are compared with one another. The new NR sequence S<NUM>,i that corresponds the largest XCORRi,umax(i) value is allocated to the existing sequence group of index umax(i), and the remaining NR sequences are labeled as unallocated.

In some embodiments, a threshold can be set as criteria for determining whether a cross correlation value is high or low. Different threshold settings can result in different sequence allocations. When allocating the new length-<NUM>, lengh-<NUM>, and length-<NUM> NR sequences, the thresholds can be set to <NUM>, <NUM>, and <NUM>, respectively.

Use the allocation of length-<NUM> NR sequences as an example, the cross correlation threshold is set to <NUM>. In this case, the cross correlations between the new length-<NUM> sequences and the existing length-<NUM>, length-<NUM>, length-<NUM>, and length-<NUM> are calculated. For example, the cross correlations can be represented in <NUM> cross correlation matrices corresponding to the length-<NUM>, lengh-<NUM>, length-<NUM>, and length-<NUM> sequences, respectively. Table-<NUM> illustrates the group indices umax(i,L) or umax(i,L,v), for which the cross correlation between (<NUM>) a new length-<NUM> sequence (of sequence index i) and (<NUM>) an existing sequence of length L within the group is higher than <NUM>, where v=<NUM>,<NUM> when L is equal or large than <NUM>.

As illustrated in the second row of Table-<NUM>, the cross correlation between new length-<NUM> sequence of sequence index i=<NUM> and existing length-<NUM> sequence of group index u=<NUM> is higher than <NUM>. Same is true for new length-<NUM> sequence of sequence index i=<NUM> and existing length-<NUM> sequence of group index u=<NUM>. In some embodiments, only one length-<NUM> sequence can be allocated to an individual sequence group. Accordingly, with respect to the sequence group of group index u=<NUM>, a further comparison of cross correlation values is performed. As calculated, the cross correlation value is <NUM> for sequence pair (sequence index i=<NUM>, group index u=<NUM>) and <NUM> for sequence pair (sequence index i=<NUM>, group index u=<NUM>). Based on the comparison, the larger cross correlation value of <NUM> is selected. Therefore, the length-<NUM> sequence of sequence index i=<NUM> is allocated to sequence group u=<NUM>, and the length-<NUM> sequence of index i=<NUM> remains unallocated.

As illustrated in the third row of Table-<NUM>, the cross correlation between new length-<NUM> sequence of sequence index i=<NUM> and existing length-<NUM> sequence of group index u=<NUM>(v=<NUM>) is higher than <NUM>. Because the new length-<NUM> sequence of sequence index i =<NUM> has already been allocated to group u=<NUM> according to the cross correlation with length-<NUM> sequences, this new sequence is not allocated to sequence group u=<NUM>. In other words, the cross correlation with length-<NUM> sequences has the highest priority in the sequence allocation process.

As illustrated in the fourth column of Table-<NUM>, the cross correlation between new length-<NUM> sequence of sequence index i=<NUM> and existing length-<NUM> sequence with of group index u=<NUM> (v=<NUM>) is higher than <NUM>. Same is true for new length-<NUM> sequence of sequence index i=<NUM> and existing length-<NUM> sequence of group index u=<NUM> (v=<NUM>). Because the new length-<NUM> sequence of index i=<NUM> has already been allocated to sequence group u=<NUM> based on the cross correlation between length-<NUM> and length-<NUM> sequences, the new length-<NUM> sequence of index i =<NUM> cannot be allocated to sequence group u=<NUM> anymore. Therefore, the new length-<NUM> sequence of index i =<NUM> is allocated to sequence group u=<NUM>. In other words, the cross correlation between sequence length pair of (<NUM>,<NUM>) has a higher priority than that of (<NUM>,<NUM>) or (<NUM>,<NUM>) in some embodiments.

Table-<NUM> illustrated a partial allocation of the new length-<NUM> NR sequences to the existing sequence groups based on the discussions above.

With continued reference to <FIG>, at block <NUM>, the method includes determining whether all of the new sequences have been allocated. If so, the method ends at block <NUM>. If not, the method proceeds to block <NUM>. At block <NUM>, the method includes determining correlations between each unallocated new sequence and sequence(s) included in each of the remaining existing sequence groups. This can be achieved in a manner similar to block <NUM>, and new cross correlation matrices (of smaller size) can be generated. Then the method proceeds back to block <NUM> to continue allocating unallocated new sequence(s) into remaining existing sequence groups.

Using the method of <FIG> in accordance with some embodiments, a final result for allocating the new length-<NUM> NR sequences into existing sequence groups based on cross correlation with the length-<NUM>, length-<NUM>, length-<NUM>, and length-<NUM> LTE sequences is illustrated in Table-<NUM> below.

Using the same method in accordance with some embodiments, a final result for allocating the new length-<NUM> NR sequences into existing sequence groups based on cross correlation with the length-<NUM>, length-<NUM>, length-<NUM>, and length-<NUM> LTE sequences and the length-<NUM> new NR sequences (after grouping in accordance with Table-<NUM>) is illustrated in Table-<NUM> below.

Using the same method in accordance with some embodiments, a final result for allocating the new length-<NUM> NR sequences into existing sequence groups based on cross correlation with the length-<NUM>, length-<NUM>, length-<NUM>, and length-<NUM> LTE sequences, the length-<NUM> new NR sequences (after grouping in accordance with Table-<NUM>) and the length-<NUM> new NR sequence (after grouping in accordance with Table-<NUM>) is illustrated in Table-<NUM> below.

Various communication nodes (e.g., UE or base station) can use the grouping of new NR sequences, as disclosed herein, for communication with other communication node(s). In LTE, the sequence group number(s) for use by a UE is determined based on a group hopping pattern and a sequence shift pattern, which is known between the base station and UE. The group hopping pattern is cell-specific and the UE can obtain the group hopping pattern based on Cell ID. A same or similar mechanism can be implemented in NR for sequence group based communication.

Alternatively or in addition, sequence group number(s) can be provided from base station to UE, for example, by higher layer signaling through RRC (Radio Resource Control), physical layer signaling through DCI (Downlink Control Information), or the like. Once a sequence group number is determined, the UE can select a suitable sequence from the sequence group for transmission, for example, based on sequence length. Sequence grouping based on the presently disclosed technology can mitigate interference between or among different cells, at least because the cross correlations between the sequences used for different cells are relatively low.

<FIG> shows an exemplary block diagram of a UE <NUM> utilizing sequence groups, in accordance with some embodiments of the presently disclosed technology. The UE <NUM> includes at least one processor <NUM> and a memory <NUM> having instructions stored thereupon. The instructions upon execution by the processor <NUM> configure the UE <NUM> to perform several operations using the various modules.

The UE <NUM> can include a sequence determining module <NUM>. The sequence determining module <NUM> can determine sequence group(s) for use by the UE (e.g., based on identification of at least a cell, user, or communication channel ), select sequence(s) from a sequence group for data transmission based thereon, or perform other sequence determining related functions, in accordance with various embodiments of the presently disclosed technology. The receiver <NUM> can receive one or more messages (e.g., including information providing or assigning sequence groups to cells), and the transmitter <NUM> can transmit data (e.g., via short PUCCH to a base station) using one or more sequences selected from sequence group(s) configured in accordance with various embodiments of the presently disclosed technology.

<FIG> shows an exemplary block diagram of a base station <NUM> managing sequence groups, in accordance with some embodiments of the presently disclosed technology. The base station <NUM> includes at least one processor <NUM> and a memory <NUM> having instructions stored thereupon. The instructions upon execution by the processor <NUM> configure the base station <NUM> to perform several operations using the various modules.

The base station <NUM> can include a sequence managing module <NUM>. The sequence managing module <NUM> can allocate and group sequences, assign sequence groups to cells, determine sequence group(s) used by UE(s), or perform other sequence related functions, in accordance with various embodiments of the presently disclosed technology. The receiver <NUM> can receive data transmitted using sequence(s) selected from sequence group(s) that are configured in accordance with various embodiments of the presently disclosed technology, and the transmitter <NUM> can transmit one or more messages (e.g., for providing or assigning sequence groups to cells) to one or more UEs.

The term "exemplary" is used to mean "an example of" and, unless otherwise stated, does not imply an ideal or a preferred embodiment.

Generally, program modules may include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types.

Claim 1:
A method for wireless communication, comprising:
transmitting information to a wireless communication node based on a length-<NUM> target sequence, wherein the length-<NUM> target sequence is a member of a target sequence set,
wherein each length-<NUM> target sequence of the target sequence set is allocated to an individual sequence group of a plurality of sequence groups, the individual sequence group having at least one length-Y sequence, wherein Y=12N and N is a positive integer that is different than <NUM>, wherein the allocation is based, at least in part, on a first value of correlation between the length-<NUM> target sequence and the at least one length-Y sequence of the individual sequence group,
wherein a group index of the individual sequence group is denoted as u, and
wherein each sequence group of the plurality of sequence groups is associated with a distinct group index u, and wherein each distinct length-<NUM> target sequence is allocated to an individual sequence group in accordance with a relationship between values of ϕ(n) and the group indices corresponding to a mathematical form of ejπϕ(n)/<NUM>, n = <NUM>,<NUM>,<NUM>,...,<NUM> that comprises: <MAT> <MAT> <MAT> <MAT> and <MAT>