Methods and apparatuses with CSI omission for linear combination port-selection codebook

1 . A method performed by a user equipment (UE) for generating and reporting a channel state information (CSI) report in a wireless communications system, the method comprising:

receiving a CSI report configuration from a network node;

determining based on the received CSI report configuration, a number of precoder coefficients for Rank Index (RI) transmission layers of a precoder vector or matrix;

grouping the precoder coefficients of the RI transmission layers into at least two coefficient subsets, each coefficient subset comprising a plurality of precoder coefficients;

assigning an ordering to said at least two coefficient subsets and an ordering to the precoder coefficients within each coefficient subset;

dividing said at least two coefficient subsets into two or more CSI groups having associated priority levels;

generating a CSI report comprising a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating the size of the payload of the CSI part 2, wherein the CSI part 2 includes the precoder coefficients of at least one of the two or more CSI groups; and

transmitting an uplink control information (UCI) including the CSI report over an uplink (UL) channel to the network node,

wherein each precoder coefficient is associated with four indices (l, p, d, n), wherein the first index, l, is a layer index, the second index, p, is a port or spatial beam index, the third index, d, is a delay index, and the fourth index, n, is a Doppler component index, and wherein grouping the precoder coefficients of the RI transmission layers into the at least two coefficient subsets is based on at least one of the delay index d or the Doppler component index n.

2 . The method of claim 1 , wherein l=0, . . . , RI−1, p=0, . . . , P′−1 or p=0, . . . , 2P′−1, d=0, . . . , D′−1, n=0, . . . , E′−1, and wherein, D′ is a number of delays, and E′ is a number of Doppler components.

3 . The method of claim 2 , wherein the precoder coefficients for the RI layers of the precoding vector or matrix are grouped into a number of non-overlapping coefficient subsets, A={A 0 , A 1 , . . . , A N-1 }, and each coefficient subset A i comprises precoder coefficients associated with D′ delays and RI transmission layers and a number of port indices.

4 . The method of claim 3 , wherein the precoder coefficients of each coefficient subset A i is further grouped into a number of coefficient subsets A i ={A i,1 , . . . , A i,T } and each coefficient subset A i,j comprises the precoder coefficients associated with one subset or two subsets of continuous port indices associated with a first and second polarization of the antenna ports, RI layers and a single delay index.

5 . The method of claim 4 , wherein the coefficient subsets A i,j are ordered with respect to an increasing delay index, and wherein the precoder coefficients of each coefficient subset A i,j are ordered with respect to an increasing port index, wherein the precoder coefficients associated with the same port index are ordered with respect to an increasing layer index.

6 . The method of claim 4 , wherein the coefficient subsets are ordered with respect to an increasing subset index.

7 . The method of claim 2 , wherein the grouping of the precoder coefficients into at least two coefficient subsets and the ordering of the coefficient subsets and the precoder coefficients within each coefficient subset are based on a new delay index d′ instead of delay index d.

8 . The method of claim 2 , wherein a precoding vector for a transmission layer is based on P′ basis vectors selected from a first basis set comprising P basis vectors, wherein, and D′ basis vectors selected from a second basis set comprising D basis vectors, and E′ basis vectors selected from a third basis set comprising E basis vectors, and a set of precoder coefficients for combining the selected basis vectors from the first and second and third basis sets.

9 . The method of claim 8 , wherein D′=D; and the precoder coefficients or the delay indices are ordered with respect to a modulo operation d′=(d−d r )mod D, wherein d′ is the new delay index, after the modulo operation, and d r is the reference delay index associated with the maximum or strongest coefficient.

10 . The method of claim 8 , wherein each basis vector from the second basis set is a DFT or IDFT vector defined over N 3 subbands or PRBs or frequency units and associated with a delay value, and each basis vector from the third basis set is a DFT or IDFT vector defined over N 4 time instants and associated with a Doppler value.

11 . The method of claim 8 , wherein the first basis set is given by a 2D-DFT matrix and wherein each basis vector is referred to as a spatial beam or spatial beam vector.

12 . The method of claim 10 , wherein the precoder coefficients per layer associated with a set of basis vectors of the second basis set are ordered with respect to basis indices f of the basis vectors, and wherein the precoder coefficients associated with the basis index f are ordered with respect to a modulo operation f t =(f−f r )mod N 3 , wherein f t ∈{0, . . . , N 3 −1} is a new basis index and f r is a reference basis index associated with a maximum or strongest coefficient.

13 . The method of claim 1 , wherein the precoder coefficients of a layer are stacked in a coefficient matrix and the CSI report comprises an indicator for indicating the location of the non-zero coefficients in the coefficient matrix, and wherein the indicator is given by a bitmap and each bit of the bitmap is associated with a precoder coefficient in the coefficient matrix, and wherein the bits in the bitmap are ordered in the same way as the coefficient subsets and the precoder coefficients in the coefficient subsets.

14 . The method of claim 13 , wherein the bits in the bitmap are ordered in the same way as the coefficient subsets and the precoder coefficients in the coefficient subsets.

15 . A method performed by a network node for receiving a channel state information (CSI) report generated by a User Equipment (UE), in a wireless communications system, the method comprising:

transmitting to the UE, a CSI report configuration for enabling the UE to determine based on the transmitted CSI report configuration a number of precoder coefficients for Rank Index (RI) transmission layers of a precoder vector or matrix; to group the precoder coefficients of the RI transmission layers into at least two coefficient subsets, each coefficient subset comprising a plurality of precoder coefficients; to assigning an ordering to said at least two coefficient subsets and an ordering to the precoder coefficients within each coefficient subset; and to divide said at least two coefficient subsets into two or more CSI groups having associated priority levels; and

receiving from the UE over an uplink channel, an UCI including the CSI report generated by the UE, the CSI report comprising a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating the size of the payload of the CSI part 2, wherein the CSI part 2 includes the precoder coefficients of at least one of the two or more CSI groups; and wherein, each precoder coefficient is associated with four indices (l, p, d, n), wherein the first index, l, is a layer index, the second index, p, is a port or spatial beam index, the third index, d, is a delay index, and the fourth index, n, is a Doppler component index, and wherein the precoder coefficients of the RI transmission layers are grouped into the at least two coefficient subsets based on at least one of the delay index d or the Doppler component index n.

16 . A User Equipment (UE) comprising a processor and a memory, said memory containing instructions executable by said processor whereby said UE is operative to:

receive a CSI report configuration from a network node;

determine based on the received CSI report configuration, a number of precoder coefficients for Rank Index (RI) transmission layers of a precoder vector or matrix;

group the precoder coefficients of the RI transmission layers into at least two coefficient subsets, each coefficient subset comprising a plurality of precoder coefficients;

assign an ordering to said at least two coefficient subsets and an ordering to the precoder coefficients within each coefficient subset;

divide said at least two coefficient subsets into two or more CSI groups having associated priority levels;

generate a CSI report comprising a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating the size of the payload of the CSI part 2, wherein the CSI part 2 includes the precoder coefficients of at least one of the two or more CSI groups; and

transmit an uplink control information (UCI) including the CSI report over an uplink (UL) channel to the network node,

wherein each precoder coefficient is associated with four indices (l, p, d, n), wherein the first index, l, is a layer index, the second index, p, is a port or spatial beam index, the third index, d, is a delay index, and the fourth index, n, is a Doppler component index, and wherein said UE is operative to group the precoder coefficients of the RI transmission layers into the at least two coefficient subsets based on at least one of the delay index d or the Doppler component index n.

17 . A network node comprising a processor and a memory, said memory containing instructions executable by said processor whereby said network node is operative to:

transmit to a User Equipment (UE), a channel state information (CSI) report configuration for enabling the UE to determine based on the transmitted CSI report configuration a number of precoder coefficients for Rank Index (RI) transmission layers of a precoder vector or matrix; to grouping the precoder coefficients of the RI transmission layers into at least two coefficient subsets, each coefficient subset comprising a plurality of precoder coefficients; to assigning an ordering to said at least two coefficient subsets and an ordering to the precoder coefficients within each coefficient subset; and to divide said at least two coefficient subsets into two or more CSI groups having associated priority levels; and

receive from the UE over an uplink channel, an UCI including the CSI report generated by the UE, the CSI report comprising a CSI part 1 and a CSI part 2, wherein the CSI part 1 has a fixed payload size and comprises information indicating the size of the payload of the CSI part 2, wherein the CSI part 2 includes the precoder coefficients of at least one of the two or more CSI groups; and wherein, each precoder coefficient is associated with four indices (l, p, d, n), wherein the first index, l, is a layer index, the second index, p, is a port or spatial beam index, the third index, d, is a delay index, and the fourth index, n, is a Doppler component index, and wherein the precoder coefficients of the RI transmission layers are grouped into the at least two coefficient subsets based on at least one of the delay index d or the Doppler component index n.