What is claimed is:1. A method for wireless communication at a transmitting device, comprising:identifying a first set of guard interval inputs and a second set of data inputs for an orthogonal frequency division multiplexed (OFDM) communication, wherein the OFDM communication has a first set of time-domain guard interval samples and a second set of time-domain data samples;determining a permutation matrix to map the first set of guard interval inputs to a subset of a set of subcarriers for the OFDM communication, the permutation matrix determined based at least in part on a first number of columns of a sub-matrix of a first matrix, wherein the first matrix is based at least in part on an inverse fast Fourier transform (IFFT) matrix that is used to generate an OFDM symbol of the OFDM communication, and wherein the first number of columns correspond to a number of subcarriers that carry the first set of time-domain guard interval samples;generating the OFDM symbol with the first set of time-domain guard interval samples and the second set of time-domain data samples based at least in part on a product of the permutation matrix and the first matrix applied to the first set of guard interval inputs and the second set of data inputs; andtransmitting the OFDM symbol to a receiving device.2. The method of claim 1, further comprising:identifying the sub-matrix of the first matrix based on a number of rows that correspond to a sum of a first number of guard interval header samples of the first set of time-domain guard interval samples and a second number of guard interval tail samples of the first set of time-domain guard interval samples, and a number of columns that correspond to the number of subcarriers that carry the first set of time-domain guard interval samples.3. The method of claim 1, wherein the IFFT matrix has a length that corresponds to a sum of a first number of time-domain guard interval samples of the first set of time-domain guard interval samples and a second number of time-domain data samples of the second set of time-domain data samples.4. The method of claim 1, further comprising:receiving configuration information that indicates the permutation matrix is to be used to generate the OFDM symbol that includes the first set of time-domain guard interval samples.5. The method of claim 4, wherein the permutation matrix is determined based at least in part on one or more parameters that are specified, that are included with the configuration information, that are determined based at least in part on one or more conditions associated with the OFDM symbol, or any combinations thereof.6. The method of claim 4, wherein the receiving the configuration information further comprises:receiving one or more parameters for determination of the permutation matrix via radio resource control (RRC) signaling, a medium access control (MAC) control element, downlink control information (DCI), or any combinations thereof.7. The method of claim 1, wherein the first number of columns of the sub-matrix are selected as quasi-equidistant columns from a total number of columns of the first matrix.8. The method of claim 7, wherein the first matrix is a product of the IFFT matrix and a sub-carrier mapping matrix, and the sub-matrix includes columns of the first matrix that correspond to a subset of active subcarriers for the OFDM symbol that do not include guard subcarriers associated with a guard band of the OFDM symbol.9. The method of claim 7, wherein the first matrix corresponds to the IFFT matrix, and the sub-matrix includes columns of the first matrix that correspond to all subcarriers for the OFDM symbol including guard subcarriers associated with a guard band of the OFDM symbol, and one or more columns of the sub-matrix that are associated with the guard subcarriers are discarded.10. The method of claim 1, wherein the determining the permutation matrix comprises:performing a QR decomposition with column pivoting on the sub-matrix to determine an ordered set of columns that are ordered according to linear independence; andselecting the first number of columns from the ordered set of columns.11. The method of claim 10, wherein the first matrix is a product of the IFFT matrix and a sub-carrier mapping matrix, and the first number of columns are selected in sequential order from an initial column of the ordered set of columns.12. The method of claim 10, wherein the first matrix corresponds to the IFFT matrix and a first subset of columns of the ordered set of columns are associated with one or more guard subcarriers for the OFDM symbol, and a second subset of columns of the ordered set of columns are associated with one or more non-guard subcarriers for the OFDM symbol, and wherein the first number of columns are selected in sequential order from the second subset of columns.13. A method for wireless communication at an access network entity, comprising:determining configuration information for a first transmitter for orthogonal frequency division multiplexed (OFDM) communication, wherein the configuration information indicates that OFDM symbols within the OFDM communication include a first set of time-domain guard interval samples and a second set of time-domain data samples, and a permutation matrix is to be used to map a first set of guard interval inputs to a subset of a set of subcarriers for the OFDM communication, wherein the permutation matrix is based at least in part on a first number of columns of a sub-matrix of a first matrix, wherein the first matrix is based at least in part on an inverse fast Fourier transform (IFFT) matrix that is used to generate an OFDM symbol of the OFDM communication, and wherein the first number of columns correspond to a number of subcarriers that carry the first set of time-domain guard interval samples;transmitting the configuration information to the first transmitter; andcommunicating with the first transmitter using guard-interval-based OFDM communications based at least in part on the configuration information.14. The method of claim 13, wherein one or more parameters for generating the permutation matrix are specified, are transmitted in the configuration information, are implicitly derived based on conditions associated with the OFDM communication, or any combinations thereof.15. The method of claim 14, wherein the one or more parameters for generating the permutation matrix are provided in radio resource control (RRC) signaling, in a medium access control (MAC) control element, in downlink control information (DCI), or any combinations thereof.16. The method of claim 13, wherein the first number of columns of the sub-matrix are selected as quasi-equidistant columns from a total number of columns of the first matrix.17. The method of claim 16, wherein the first matrix is a product of the IFFT matrix and a sub-carrier mapping matrix, and the sub-matrix includes columns of the first matrix that correspond to a subset of active subcarriers for the OFDM symbol that do not include guard subcarriers associated with a guard band of the OFDM symbol.18. The method of claim 16, wherein the first matrix corresponds to the IFFT matrix, and the sub-matrix includes columns of the first matrix that correspond to all subcarriers for the OFDM symbol including guard subcarriers associated with a guard band of the OFDM symbol, and one or more columns of the sub-matrix that are associated with the guard subcarriers are discarded.19. The method of claim 13, wherein the first number of columns of the sub-matrix are selected by performing a QR decomposition with column pivoting on the sub-matrix to determine an ordered set of columns that are ordered according to linear independence, and selecting the first number of columns from the ordered set of columns.20. The method of claim 19, wherein the first matrix is a product of the IFFT matrix and a sub-carrier mapping matrix, and the first number of columns are selected in sequential order from an initial column of the ordered set of columns.21. The method of claim 19, wherein the first matrix corresponds to the IFFT matrix and a first subset of columns of the ordered set of columns are associated with one or more guard subcarriers for the OFDM symbol, and a second subset of columns of the ordered set of columns are associated with one or more non-guard subcarriers for the OFDM symbol, and wherein the first number of columns are selected in sequential order from the second subset of columns.22. An apparatus for wireless communication at a transmitting device, comprising:a processor;memory coupled with the processor; andinstructions stored in the memory and executable by the processor to cause the apparatus to:identify a first set of guard interval inputs and a second set of data inputs for an orthogonal frequency division multiplexed (OFDM) communication, wherein the OFDM communication has a first set of time-domain guard interval samples and a second set of time-domain data samples;determine a permutation matrix to map the first set of guard interval inputs to a subset of a set of subcarriers for the OFDM communication, the permutation matrix determined based at least in part on a first number of columns of a sub-matrix of a first matrix, wherein the first matrix is based at least in part on an inverse fast Fourier transform (IFFT) matrix that is used to generate an OFDM symbol of the OFDM communication, and wherein the first number of columns correspond to a number of subcarriers that carry the first set of time-domain guard interval samples;generate the OFDM symbol with the first set of time-domain guard interval samples and the second set of time-domain data samples based at least in part on a product of the permutation matrix and the first matrix applied to the first set of guard interval inputs and the second set of data inputs; andtransmit the OFDM symbol to a receiving device.23. The apparatus of claim 22, wherein the instructions are further executable by the processor to cause the apparatus to:identify the sub-matrix of the first matrix based on a number of rows that correspond to a sum of a first number of guard interval header samples of the first set of time-domain guard interval samples and a second number of guard interval tail samples of the first set of time-domain guard interval samples, and a number of columns that correspond to the number of subcarriers that carry the first set of time-domain guard interval samples.24. The apparatus of claim 22, wherein the IFFT matrix has a length that corresponds to a sum of a first number of time-domain guard interval samples of the first set of time-domain guard interval samples and a second number of time-domain data samples of the second set of time-domain data samples.25. The apparatus of claim 22, wherein the instructions are further executable by the processor to cause the apparatus to:receive configuration information that indicates the permutation matrix is to be used to generate the OFDM symbol that includes the first set of time-domain guard interval samples.26. An apparatus for wireless communication at an access network entity, comprising:a processor;memory coupled with the processor; andinstructions stored in the memory and executable by the processor to cause the apparatus to:determine configuration information for a first transmitter for orthogonal frequency division multiplexed (OFDM) communication, wherein the configuration information indicates that OFDM symbols within the OFDM communication include a first set of time-domain guard interval samples and a second set of time-domain data samples, and a permutation matrix is to be used to map a first set of guard interval inputs to a subset of a set of subcarriers for the OFDM communication, wherein the permutation matrix is based at least in part on a first number of columns of a sub-matrix of a first matrix, wherein the first matrix is based at least in part on an inverse fast Fourier transform (IFFT) matrix that is used to generate an OFDM symbol of the OFDM communication, and wherein the first number of columns correspond to a number of subcarriers that carry the first set of time-domain guard interval samples;transmit the configuration information to the first transmitter; andcommunicate with the first transmitter using guard-interval-based OFDM communications based at least in part on the configuration information.27. The apparatus of claim 26, wherein one or more parameters for generating the permutation matrix are specified, are transmitted in the configuration information, are implicitly derived based on conditions associated with the OFDM communication, or any combinations thereof.28. The apparatus of claim 27, wherein the one or more parameters for generating the permutation matrix are provided in radio resource control (RRC) signaling, in a medium access control (MAC) control element, in downlink control information (DCI), or any combinations thereof.