# US 2021/0243061 A1 · Efficient Synthesis and Analysis of OFDM and MIMO-OFDM Signals > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0243061 A1 - Document ID: US20210243061A1 - Status: Published application - Kind: A1 - Application number: 17/234,519 - Filed: 2021-04-19 - Published: 2021-08-05 - Earliest claimed: 2017-06-30 - Assignees: Genghiscomm Holdings, LLC - Applicants: Genghiscomm Holdings, LLC - Inventors: Steve Shattil - Web page: https://patentgrep.com/patent/US20210243061A1 ## CPC - H04L 27/2614: {Peak power aspects} - H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting - H04B 7/0465: {taking power constraints at power amplifier or emission constraints, e.g. constant modulus, into account} - H04L 27/2634: {Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation} - H04B 7/024: Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems - Y02D 30/70: in wireless communication networks - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04B: TRANSMISSION - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract Disclosed techniques for improving computational efficiency can be applied to synthesis and analysis in digital signal processing. A base discrete-time Orthogonal Frequency Division Multiplexing (OFDM) signal is generated by performing at least one linear transform, including an inverse discrete Fourier transform (IDFT), on a first matrix of data symbols. A sparse data matrix is provided as an update to the first matrix of data symbols. The at least one linear transform is performed on the sparse data matrix to generate an update discrete-time OFDM signal. The update discrete-time OFDM signal and the base discrete-time OFDM signal are summed to produce an updated discrete-time OFDM signal. ## Claims ### Claim 1 A method, comprising: performing at least one linear transform on a first matrix of data symbols to produce a base discrete-time Orthogonal Frequency Division Multiplexing (OFDM) signal; generating a sparse data matrix; performing the at least one linear transform on the sparse data matrix to generate an update discrete-time OFDM signal; and summing the update discrete-time OFDM signal with the base discrete-time OFDM signal to produce an updated discrete-time OFDM signal. ### Claim 2 (depends on 1) The method of claim 1, further comprising measuring a peak-to-average-power ratio (PAPR) of the updated discrete-time OFDM signal; comparing the PAPR to at least one PAPR measurement corresponding to at least one other discrete-time OFDM signal; and selecting a discrete-time OFDM signal having the lowest PAPR. ### Claim 3 (depends on 1) The method of claim 1, wherein the data symbols comprise at least one of user data, control information, or reference symbols. ### Claim 4 (depends on 1) The method of claim 1, further comprising transmitting the updated discrete-time OFDM signal. ### Claim 5 (depends on 1) The method of claim 1, wherein the data symbols comprise at least one of transform-precoded data symbols, spread data symbols, and Multiple Input, Multiple Output (MIMO) precoded data symbols. ### Claim 6 (depends on 1) The method of claim 1, wherein the sparse data matrix is a square matrix or a vector. ### Claim 7 (depends on 1) The method of claim 1, further comprising designating the updated discrete-time OFDM signal to be used as the base discrete-time OFDM signal in a next iteration. ### Claim 8 (depends on 1) The method of claim 1, wherein the linear transform comprises at least one of discrete Fourier transform spread OFDM precoding, single-carrier frequency division multiple access precoding, and Multiple Input, Multiple Output precoding. ### Claim 9 An apparatus, comprising at least one processor, at least one memory in electronic communication with the at least one processor, and instructions stored in the at least one memory, the instructions executable by the at least one processor for: performing at least one linear transform on a first matrix of data symbols to produce a base discrete-time Orthogonal Frequency Division Multiplexing (OFDM) signal; generating a sparse data matrix; performing the at least one linear transform on the sparse data matrix to generate an update discrete-time OFDM signal; and summing the update discrete-time OFDM signal with the base discrete-time OFDM signal to produce an updated discrete-time OFDM signal. ### Claim 10 (depends on 9) The apparatus of claim 9, further comprising measuring a peak-to-average-power ratio (PAPR) of the updated discrete-time OFDM signal; comparing the PAPR to at least one PAPR measurement corresponding to at least one other discrete-time OFDM signal; and selecting a discrete-time OFDM signal corresponding to the lowest PAPR. ### Claim 11 (depends on 9) The apparatus of claim 9, wherein the data symbols comprise at least one of user data, control information, or reference symbols. ### Claim 12 (depends on 9) The apparatus of claim 9, further comprising transmitting the updated discrete-time OFDM signal. ### Claim 13 (depends on 9) The apparatus of claim 9, further comprising designating the updated discrete-time OFDM signal to be used as the base discrete-time OFDM signal in a next iteration. ### Claim 14 (depends on 9) The apparatus of claim 9, wherein the data symbols comprise at least one of transform-precoded data symbols, spread data symbols, and Multiple Input, Multiple Output (MIMO) precoded data symbols. ### Claim 15 (depends on 9) The apparatus of claim 9, wherein the sparse data matrix is a square matrix or a vector. ### Claim 16 (depends on 9) The apparatus of claim 9, wherein the linear transform comprises at least one of discrete Fourier transform spread OFDM precoding, single-carrier frequency division multiple access precoding, and Multiple Input, Multiple Output precoding. ### Claim 17 A computer program product, comprising a non-transitory computer readable hardware storage device having computer readable program code stored therein, said program code containing instructions executable by one or more processors of a computer system to implement a method comprising: performing at least one linear transform on a first matrix of data symbols to produce a base discrete-time Orthogonal Frequency Division Multiplexing (OFDM) signal; generating a sparse data matrix; performing the at least one linear transform on the sparse data matrix to generate an update discrete-time OFDM signal; and summing the update discrete-time OFDM signal with the base discrete-time OFDM signal to produce an updated discrete-time OFDM signal. ### Claim 18 (depends on 17) The computer program product of claim 17, wherein said program code contains instructions executable by one or more processors for measuring a peak-to-average-power ratio (PAPR) of the updated discrete-time OFDM signal; comparing the PAPR to at least one PAPR measurement corresponding to at least one other discrete-time OFDM signal; and selecting a discrete-time OFDM signal corresponding to the lowest PAPR. ### Claim 19 (depends on 17) The computer program product of claim 17, wherein the data symbols comprise at least one of user data, control information, or reference symbols. ### Claim 20 (depends on 17) The computer program product of claim 17, wherein said program code contains instructions executable by one or more processors for transmitting the updated discrete-time OFDM signal. ### Claim 21 (depends on 17) The computer program product of claim 17, wherein said program code contains instructions executable by one or more processors for designating the updated discrete-time OFDM signal to be used as the base discrete-time OFDM signal in a next iteration. ### Claim 22 (depends on 17) The computer program product of claim 17, wherein the data symbols comprise at least one of transform-precoded data symbols, spread data symbols, and Multiple Input, Multiple Output (MIMO) precoded data symbols. ### Claim 23 (depends on 17) The computer program product of claim 17, wherein the sparse update matrix is a square matrix or a vector. ### Claim 24 (depends on 17) The computer program product of claim 17, wherein the linear transform comprises at least one of discrete Fourier transform spread OFDM precoding, single-carrier frequency division multiple access precoding, and Multiple Input, Multiple Output precoding.