# US 9,438,321 B2 · Methods and apparatus for codebook subset restriction for two-dimensional advanced antenna systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,321 B2 - Document ID: US9438321B2 - Status: Granted - Kind: B2 - Application number: 13/939,934 - Filed: 2013-07-11 - Published: 2014-01-16 - Granted: 2016-09-06 - Earliest claimed: 2012-07-12 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., LTD - Inventors: Thomas David Novlan; Krishna Sayana; Young-Han Nam; Jin-Kyu Han - Web page: https://patentgrep.com/patent/US9438321B2 ## CPC - H04B 7/0417: Feedback systems - H04B 7/0469: {taking special antenna structures, e.g. cross polarized antennas into account} - H04B 7/0479: {for multi-dimensional arrays, e.g. horizontal or vertical pre-distortion matrix index [PMI]} - H04B 7/0481: {using subset selection of codebooks} - H04B: TRANSMISSION ## Abstract A user equipment (UE) in a wireless network having two-dimensional antenna systems performs a method of codebook sampling. The method includes receiving from an eNodeB (eNB) an indication of a restricted subset M of vertical precoding matrices, wherein M is less than a total number of vertical precoding matrices N in a codebook, the codebook comprising a plurality of vertical precoding matrices and horizontal precoding matrices. The method also includes feeding back vertical precoding matrix indicators (V-PMI) to the eNB based on the restricted subset of vertical precoding matrices. ## Claims ### Claim 1 For use in a user equipment (UE) in a wireless network having two-dimensional antenna systems, a method of codebook sampling, the method comprising: receiving from an eNodeB (eNB) an indication of one or more restricted subsets M of vertical precoding matrices or non-subset restricted precoding matrix indicator (PMI) selection modes, wherein M is less than a total number of vertical precoding matrices N in a codebook and wherein the indication of the restricted subset or the non-subset restricted PMI selection modes is configurable by the network and received form the eNB through a higher layer signalling in conjunction with one or more changed feedback configurations, the codebook comprising a plurality of vertical precoding matrices and horizontal precoding matrices; and feeding back vertical precoding matrix indicators (V-PMI) to the eNB based on the restricted subset of vertical precoding matrices, wherein separate bitmaps are defined for subset restriction of Vertical and Horizontal precoders V and H individually, and wherein at least two bitmaps, AV and AH are with lengths NV and NH, wherein the lengths are configured by higher layers. ### Claim 2 (depends on 1) The method of claim 1, wherein the indication of the one or more restricted subsets M is received when the feedback to the eNB is periodic, the method further comprising receiving an indication of an unrestricted subset of vertical precoding matrices when the feedback to the eNB is aperiodic. ### Claim 3 (depends on 1) The method of claim 1, wherein the one or more subsets M are restricted based on at least one of a coarse sampling factor KC and a fine sampling factor KF, each sampling factor configured by the network and associated with a range of transmission angles in a vertical direction. ### Claim 4 (depends on 3) The method of claim 3, wherein a subset restriction search space for fine sampling is determined based on a corresponding subset restriction search space for coarse sampling. ### Claim 5 (depends on 1) The method of claim 1, wherein the one or more subsets M are based on a window of vertical precoding matrices in the codebook, the window having a predetermined starting point C and a predetermined length M. ### Claim 6 (depends on 5) The method of claim 5, wherein the one or more subsets M comprises every K-th element in the window of vertical precoding matrices, where K is a predetermined integer. ### Claim 7 (depends on 1) The method of claim 1, further comprising: determining a restricted subset of horizontal precoding matrices, wherein the subset restriction of vertical precoding matrices and horizontal precoding matrices is configured jointly based on a value of a single indicator for both vertical precoding matrices and horizontal precoding matrices. ### Claim 8 (depends on 1) The method of claim 1, wherein a codebook subset restriction is received using a bitmap in a UE-specific manner. ### Claim 9 (depends on 8) The method of claim 8, wherein separate bitmaps are defined for subset restriction of Vertical and Horizontal precoders V and H individually. ### Claim 10 (depends on 8) The method of claim 8 wherein at least two bitmaps, AV and AH are respectively defined according to a first equation: AV={aNV-1V, . . . , a3V, a2V, a1V, a0V}; and a second equation: AH={aNH-1H, . . . , a3H, a2H, a1H, a0H}. ### Claim 11 (depends on 1) The method of claim 1, wherein the indication is configured to at least one of: indicate a number of antenna ports per polarization in dimension x as used for transmission of CSI reference signals; or indicate a spatial over-sampling rate in dimension x as used for transmission of CSI reference signals. ### Claim 12 A user equipment (UE) configured for communication with an eNodeB (eNB) in a wireless network having two-dimensional antenna systems, the UE comprising: at least one antenna; and a processor coupled to the at least one antenna, the processor configured to: receive from the eNB an indication of one or more restricted subsets M of vertical precoding matrices or non-subset restricted precoding matrix indicator (PMI) selection modes, wherein M is less than a total number of vertical precoding matrices N in a codebook and wherein the indication of the restricted subset or the non-subset restricted PMI selection modes is configurable by the network and received form the eNB through a higher layer signalling in conjunction with one or more changed feedback configurations, the codebook comprising a plurality of vertical precoding matrices and horizontal precoding matrices; and feed back, via the at least one antenna, vertical precoding matrix indicators (V-PMI) to the eNB based on the restricted subset of vertical precoding matrices, wherein separate bitmaps are defined for subset restriction of Vertical and Horizontal precoders V and H individually, and wherein at least two bitmaps, AV and AH are with lengths NV and NH wherein the lengths are configured by higher layers. ### Claim 13 (depends on 12) The UE of claim 12, wherein the indication of the one or more restricted subsets M is received when the feedback to the eNB is periodic, the processor further configured to receive an indication of an unrestricted subset of vertical precoding matrices when the feedback to the eNB is aperiodic. ### Claim 14 (depends on 12) The UE of claim 12, wherein the one or more subsets M are restricted based on at least one of a coarse sampling factor KC and a fine sampling factor KF, each sampling factor configured by the network and associated with a range of transmission angles in a vertical direction. ### Claim 15 (depends on 14) The UE of claim 14, wherein a subset restriction search space for fine sampling is determined based on a corresponding subset restriction search space for coarse sampling. ### Claim 16 (depends on 12) The UE of claim 12, wherein the one or more subsets M are based on a window of vertical precoding matrices in the codebook, the window having a predetermined starting point C and a predetermined length M. ### Claim 17 (depends on 16) The UE of claim 16, wherein the one or more subsets M comprises every K-th element in the window of vertical precoding matrices, where K is a predetermined integer. ### Claim 18 (depends on 12) The UE of claim 12, the processor further configured to: determine a restricted subset of horizontal precoding matrices, wherein the subset restriction of vertical precoding matrices and horizontal precoding matrices is configured jointly based on a value of a single indicator for both vertical precoding matrices and horizontal precoding matrices. ### Claim 19 An eNodeB (eNB) configured for communication with a plurality of user equipments (UEs) in a wireless network having two-dimensional antenna systems, the eNB comprising: at least one antenna; and a processor coupled to the at least one antenna, the processor configured to: transmit to a UE an indication of one or more restricted subsets M of vertical precoding matrices or non-subset restricted precoding matrix indicator (PMI) selection modes, wherein M is less than a total number of vertical precoding matrices N in a codebook and wherein the indication of the restricted subset or the non-subset restricted PMI selection modes is configurable by the network and received form the eNB through a higher layer signalling in conjunction with one or more changed feedback configurations, the codebook comprising a plurality of vertical precoding matrices and horizontal precoding matrices; and receive feedback from the UE, the feedback comprising a plurality of vertical precoding matrix indicators (V-PMI) based on the restricted subset of vertical precoding matrices, wherein separate bitmaps are defined for subset restriction of Vertical and Horizontal precoders V and H individually, and wherein at least two bitmaps, AV and AH are with lengths NV and NH wherein the lengths are configured by higher layers. ### Claim 20 (depends on 19) The eNB of claim 19, wherein the indication of the one or more restricted subsets M is transmitted when the feedback from the UE is periodic, the processor further configured to transmit an indication of an unrestricted subset of vertical precoding matrices when the feedback from the UE is aperiodic. ### Claim 21 (depends on 19) The eNB of claim 19, wherein the one or more subsets M are restricted based on at least one of a coarse sampling factor KC and a fine sampling factor KF, each sampling factor configured by the network and associated with a range of transmission angles in a vertical direction. ### Claim 22 (depends on 21) The eNB of claim 21, wherein a subset restriction search space for fine sampling is determined based on a corresponding subset restriction search space for coarse sampling. ### Claim 23 (depends on 19) The eNB of claim 19, wherein the one or more subsets M are based on a window of vertical precoding matrices in the codebook, the window having a predetermined starting point C and a predetermined length M. ### Claim 24 (depends on 23) The eNB of claim 23, wherein the one or more subsets M comprises every K-th element in the window of vertical precoding matrices, where K is a predetermined integer. ### Claim 25 (depends on 19) The eNB of claim 19, the processor further configured to: transmit to a UE an indication of a restricted subset of horizontal precoding matrices, wherein the subset restriction of vertical precoding matrices and horizontal precoding matrices is configured jointly based on a value of a single indicator for both vertical precoding matrices and horizontal precoding matrices.