# US 2017/0288751 A1 · Methods and devices for determining precoder parameters in a wireless communication network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0288751 A1 - Document ID: US20170288751A1 - Status: Published application - Kind: A1 - Application number: 15/592,338 - Filed: 2017-05-11 - Published: 2017-10-05 - Earliest claimed: 2016-03-31 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget Lm Ericsson (Publ) - Inventors: Sebastian FAXÉR; Svante BERGMAN - Web page: https://patentgrep.com/patent/US20170288751A1 ## CPC - H04B 7/0465: {taking power constraints at power amplifier or emission constraints, e.g. constant modulus, into account} - H04B 7/0408: using two or more beams, i.e. beam diversity - H04B 7/0417: Feedback systems - H04B 7/0452: Multi-user MIMO systems - H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting - H04B 7/0481: {using subset selection of codebooks} - H04B 7/0617: {for beam forming} - H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]} - H04B 7/0634: {Antenna weights or vector/matrix coefficients} - H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection} - H04B 7/06952: {Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping} - H04B 7/088: {using beam selection} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04B 7/0469: {taking special antenna structures, e.g. cross polarized antennas into account} - H04W 72/0446: Resources in time domain, e.g. slots or frames - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A method and a device for determining parameters of a precoder in a wireless communication system are disclosed. According to one aspect, a method includes selecting a subset of beams corresponding to a plurality of orthogonal beams; obtaining power levels of the selected subset of beams for generating a first factor of the precoder and obtaining phases of the selected subset of beams for generating a second factor, wherein the first factor and the second factor are part of the parameters of the precoder. ## Claims ### Claim 1 A method for a wireless device for determining parameters of a precoder, in a wireless communication system, the method comprising: selecting a subset of beams from a plurality of orthogonal beams; obtaining power levels of the selected subset of beams for generating a first factor of the precoder; and obtaining phases of the selected subset of beams for generating a second factor of the precoder; wherein the first factor and the second factor are part of the parameters of the precoder. ### Claim 2 (depends on 1) The method of claim 1, wherein the power levels of the selected subset of beams are the same for all layers of a multi-layer transmission and the phases are specific to each individual layer of the multi-layer transmission. ### Claim 3 (depends on 1) The method of claim 1, wherein the parameters of the precoder are sent in a Channel State Information (CSI) feedback report to the network node. ### Claim 4 (depends on 1) The method of claim 1, wherein the selected subset of beams corresponds to transmission on a single polarization. ### Claim 5 (depends on 1) The method of claim 1, wherein the selected subset of beams is selected in polarization pairs, each polarization pair corresponding to a dual polarized (DP) beam. ### Claim 6 (depends on 1) The method of claim 1, wherein the selected subset of beams is selected by determining beams which have a largest wideband received power. ### Claim 7 (depends on 1) The method of claim 1, further comprising sorting the selected subset of beams in order of power strength and quantizing a first beam that is of less strength than a second beam with a coarser quantization. ### Claim 8 (depends on 1) The method of claim 1, further comprising specifying an index of a strongest beam of the selected subset of beams and wherein the rest of the beams in the selected subset is specified in an unordered fashion in a report to the network node. ### Claim 9 (depends on 1) The method of claim 1, wherein the power levels of the selected subset of beams are quantized at a first quantization resolution and the phases of the selected subset of beams are quantized at a second quantization resolution. ### Claim 10 (depends on 9) The method of claim 9, further comprising sending the quantized power levels and quantized phases to the network node. ### Claim 11 (depends on 1) The method of claim 1, wherein the first factor is generated for a first frequency granularity and the second factor is a function of a second frequency granularity. ### Claim 12 (depends on 11) The method of claim 11, wherein the first frequency granularity corresponds to an entire frequency bandwidth and the second frequency granularity corresponds to a frequency subband within the frequency bandwidth. ### Claim 13 (depends on 1) The method of claim 1, wherein, for a precoder of rank 2, the phases of the selected subset of beams for a first layer is a function of the phases of the selected subset of beams for a second layer. ### Claim 14 (depends on 1) The method of claim 1, wherein the power levels are uniformly quantized between a first value and a second value, wherein the first value is a minimum power level. ### Claim 15 A wireless device for determining parameters of a precoder, in a wireless communication system, the wireless device comprising a processing circuitry configure to: select a subset of beams from a plurality of orthogonal beams; obtain power levels of the selected subset of beams for generating a first factor of the precoder; and obtain phases of the selected subset of beams for generating a second factor of the precoder; wherein the first factor and the second factor are part of the parameters of the precoder. ### Claim 16 (depends on 15) The wireless device of claim 15, wherein the processing circuitry comprises a processor, a memory and a network interface both connected to the processor, the memory containing instructions that, when executed, cause the processor to select the subset of beams, to obtain the power levels and the phases of the selected subset of beams. ### Claim 17 (depends on 15) The wireless device of claim 15, wherein the power levels of the selected subset of beams are the same for all layers of a multi-layer transmission and the phases are specific to each individual layer of the multi-layer transmission. ### Claim 18 (depends on 16) The wireless device of claim 16, wherein the processor is configured to send the parameters of the precoder in a Channel State Information (CSI) feedback report to the network node. ### Claim 19 (depends on 15) The wireless device of claim 15, wherein the selected subset of beams corresponds to transmission on a single polarization. ### Claim 20 (depends on 16) The wireless device of claim 16, wherein the processor is configured to select the subset of beams in polarization pairs, each polarization pair corresponding to a dual polarized (DP) beam. ### Claim 21 (depends on 16) The wireless device of claim 16, wherein the processor is further configured to select the subset of beams by determining beams which have a largest wideband received power. ### Claim 22 (depends on 16) The wireless device of claim 16, wherein the processor is configured to sort the selected subset of beams in order of power strength and to quantize a first beam that is of less strength than a second beam with a coarser quantization. ### Claim 23 (depends on 16) The wireless device of claim 16, wherein the processor is configured to specify an index of a strongest beam of the selected subset of beams and wherein the rest of the beams in the selected subset is specified in an unordered fashion in a report to the network node. ### Claim 24 (depends on 16) The wireless device of claim 16, wherein the processor is configured to quantize the power levels of the selected subset of beams at a first quantization resolution and the phases of the selected subset of beams at a second quantization resolution. ### Claim 25 (depends on 24) The wireless device of claim 24, wherein the processor is configured to send the quantized power levels and quantized phases to the network node. ### Claim 26 (depends on 15) The wireless device of claim 15, wherein the first factor is generated for a first frequency granularity and the second factor is a function of a second frequency granularity. ### Claim 27 (depends on 26) The wireless device of claim 26, wherein the first frequency granularity corresponds to an entire frequency bandwidth and the second frequency granularity corresponds to a frequency subband within the frequency bandwidth. ### Claim 28 (depends on 15) The method of claim 15, wherein, for a precoder of rank 2, the phases of the selected subset of beams for a first layer is a function of the phases of the selected subset of beams for a second layer. ### Claim 29 (depends on 16) The wireless device of claim 16, wherein the processor is configured to quantize uniformly the power levels between a first value and a second value, wherein the first value is a minimum power level. ### Claim 30 A method for determining transmission parameters in a wireless communication system, the method comprising: responsive to transmitting reference signals to the wireless device, receiving precoder parameters which include a subset of beams selected from a plurality of orthogonal beams, a first factor associated with power levels of the selected subset of beams, and a second factor associated with phases of the selected subset of beams; and determining the transmission parameters based on the received precoder parameters. ### Claim 31 A network node for determining transmission parameters in a wireless communication system, the network node comprising a processing circuitry configured to cause the network node to: responsive to transmitting reference signals to the wireless device, receive precoder parameters which include a subset of beams selected from a plurality of orthogonal beams, a first factor associated with power levels of the selected subset of beams, and a second factor associated with phases of the selected subset of beams; and determine the transmission parameters based on the received precoder parameters. ### Claim 32 (depends on 31) The network node of claim 31, wherein the processing circuitry comprises a processor, a memory and a network interface both connected to the processor, the memory containing instructions that, when executed, cause the processor to perform the operations of receiving and determining.