# US 2014/0192848 A1 · Sending information at a band edge within an orthogonal frequency-division multiplexing (ofdm) symbol > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192848 A1 - Document ID: US20140192848A1 - Status: Published application - Kind: A1 - Application number: 13/738,928 - Filed: 2013-01-10 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: Intel Corporation - Inventors: BHASKAR RAO; QINGHUA LI - Web page: https://patentgrep.com/patent/US20140192848A1 ## CPC - H04L 27/26265: {Arrangements for sidelobes suppression specially adapted to multicarrier systems, e.g. spectral precoding} - H04L 5/00: Arrangements affording multiple use of the transmission path - H04L 25/03828: {Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties (partial response systems H04L25/497)} - H04L 27/2634: {Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation} - H04L 25/03019: {adaptive, i.e. capable of adjustment during data reception} - H04L 25/03821: {Inter-carrier interference cancellation [ICI]} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Technology is discussed for increasing the spectral efficiency of an Orthogonal Frequency-Division Multiplexing (OFDM) symbol. Spectral efficiency can be increased by adding information to a band edge of the OFDM symbol in connection with measures taken to reduce OOB spectral leakage from the OFDM symbol. Spectral leakage reduction measures can include application of a tapering window to at least a portion of OFDM data in the time domain to reduce power in side-lobes in the frequency domain. In some examples, such measures can comprise reducing transmission power at certain frequencies for a set of adjacent sub-carriers within the OFDM symbol at or near the band edge of the OFDM symbol. The additional bandwidth at the OFDM symbol can be used for many different applications, such as, without limitation, Device-to-Device (D2D) communication and/or Machine-to-Machine (M2M) communication. ## Claims ### Claim 1 A device for sending, from a transmitter located in one of an evolved NodeB (eNodeB) and a User Equipment (UE), information at a band edge of an Orthogonal Frequency-Division Multiplexing (OFDM) symbol, comprising: a windowing module configured to apply a tapering window to at least a part of an OFDM symbol, the tapering window selected to reduce Out Of Band (OOB) spectral leakage in order to enable placement of information at the band edge of the OFDM symbol; a data module configured to provision the information to the OFDM symbol at the band edge; and a transmission module, the transmission module configured to transmit the OFDM symbol with the additional information in the band edge after application of the tapering window. ### Claim 2 (depends on 1) The device of claim 1, wherein the windowing module applies the tapering window over a windowing interval substantially equal to an inverse of a sub-carrier bandwidth for a sub-carrier within the OFDM symbol to preserve orthogonality between sub-carriers. ### Claim 3 (depends on 1) The device of claim 1, wherein the windowing module applies the tapering window to the at least a part of the OFDM symbol after an Inverse Discrete Fourier Transform (IDFT) has been applied to data within the OFDM symbol, but before a Cyclic Prefix (CP) is added to the OFDM symbol. ### Claim 4 (depends on 1) The device of claim 1, further comprising an equalization module, the equalization module configured to: select Inter-Carrier Interference (ICI) coefficient information corresponding to the tapering window applied at the transmitter, wherein the ICI coefficient information is known a-priori for the tapering window selected; and provision the ICI coefficient information to the transmission module for transmission to a receiving device to enable the receiving device to equalize a signal associated with the OFDM symbol by removing ICI in adjacent sub-carriers within the OFDM symbol with the ICI coefficient information. ### Claim 5 (depends on 1) The device of claim 1, further comprising an allocation module configured to increase a distance between sub-carriers carrying data within the OFDM symbol by an amount to offset an increase in a first main-lobe size corresponding to the tapering window relative to the first main-lobe size corresponding to a rectangular window, the distance created by including a number of sub-carriers not carrying data between sub-carriers carrying data. ### Claim 6 (depends on 1) The device of claim 1, wherein the data module provisions the information for at least one communication link that pertains to at least one of a Device-to-Device (D2D) communication application and a Machine to Machine (M2M) communication application. ### Claim 7 A method for utilizing bandwidth at an Orthogonal Frequency-Division Multiplexing (OFDM) symbol band edge, comprising: transmitting, from a transmitter located in one of an evolved NodeB (eNodeB) and a User Equipment (UE), data in an inbound span of sub-carriers of an Orthogonal Frequency-Division Multiplexing (OFDM) symbol at a first power range, the OFDM symbol comprising at least the inbound span of sub-carriers and at least one edge span of sub-carriers, wherein: the inbound span occupies a range of frequencies with a low frequency boundary and a high frequency boundary, and the at least one edge span occupies a range of frequencies that is at least one of adjacent to and below the low frequency boundary and adjacent to and above the high frequency boundary; and transmitting data in a portion of the at least one edge span at a second power range that is lower than the first power range of the inbound span. ### Claim 8 (depends on 7) The method of claim 7, further comprising determining, for a given power level in the second power range, a number of sub-carriers in the at least one edge span to reduce Out-Of-Band (OOB) spectral leakage to be below a permissibility threshold. ### Claim 9 (depends on 7) The method of claim 7, further comprising determining, for a given number of sub-carriers, a power level in the second power range for the at least one edge span to reduce Out-Of-Band (OOB) spectral leakage to be below a permissibility threshold. ### Claim 10 (depends on 7) The method of claim 7, wherein transmitting data in the portion of the at least one edge span further comprises transmitting data in multiple sub-spans at multiple different sub-power levels, wherein: the second power range comprises the multiple different sub-power levels; and the at least one edge span comprises the multiple sub-spans. ### Claim 11 (depends on 7) The method of claim 7, further comprising transmitting data in at least one transition span of sub-carriers at a low sub-power range within the first power range that is higher than the second power range and lower than a high power range within the first power range of the inbound span, wherein: the inbound span comprises a central span of sub-carriers transmitted at the high sub-power range and the at least one transition span of sub-carriers transmitted at the low sub-power range; and the at least one transition span occupies a range of frequencies that is at least one of: below frequencies occupied by the central span and above the low frequency boundary, and above the frequencies occupied by the central span and below the high frequency boundary. ### Claim 12 (depends on 11) The method of claim 11, further comprising determining a number of sub-carriers in the at least one transition span for a given power level within the low sub-power range within the first power range to reduce spectral leakage from the inbound span into an Out-Of-Band (OOB) region not designated for the OFDM symbol below an acceptability threshold. ### Claim 13 (depends on 11) The method of claim 11, further comprising determining a power level within the low sub-power range within the first power range for a given number of sub-carriers in the at least one transition span to reduce spectral leakage from the inbound span into an Out-Of-Band (OOB) region not designated for the OFDM symbol below an acceptability threshold. ### Claim 14 (depends on 11) The method of claim 11, wherein transmitting data in the at least one transition span further comprises transmitting data in multiple sub-transition-spans at multiple different sub-power levels, wherein: the low sub-power range of the first power range comprises the multiple different sub-power levels; and, the at least one transition span comprises the multiple sub-transition-spans. ### Claim 15 (depends on 7) The method of claim 7, wherein a remaining portion of the at least one edge span receives substantially no transmission power. ### Claim 16 (depends on 7) The method of claim 7, further comprising assigning power levels within the at least one transition span and the at least one edge span so that a total power arrived at by integrating over all frequencies pertaining to the OFDM symbol remains substantially unchanged relative to a scenario where transmission power is constant across the inbound span and no power is allocated to the at least one edge span, where a value of the transmission power for the scenario is determined by an existing, legacy Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) implementation as set forth in at least one of Release 8, Release 9, and Release 10. ### Claim 17 (depends on 7) The method of claim 7, further comprising determining a transmission distance, the transmission distance set to insure a reduced transmission power for the second power range for the at least one edge span of the OFDM symbol can meet communication standards of a given receiver for a distance below the transmission distance. ### Claim 18 (depends on 17) The method of claim 17, further comprising: determining the given receiver is located at a distance below the transmission distance; and provisioning information specific to the given receiver for inclusion in the at least one edge span of the OFDM symbol. ### Claim 19 A transmitter, located in one of an evolved NodeB (eNodeB) and a User Equipment (UE), operable to utilize an Orthogonal Frequency-Division Multiplexing (OFDM) band edge, comprising: reducing spectral leakage from an inbound region of an Orthogonal Frequency-Division Multiplexing (OFDM) into an Out-Of-Band (OOB) region not designated for the OFDM symbol; provisioning additional information to a band edge of the OFDM for transmission; and transmitting the OFDM symbol with the additional information in the band edge. ### Claim 20 (depends on 19) The computer program product of claim 19, wherein reducing spectral leakage further comprises applying a tapering window to the OFDM symbol. ### Claim 21 (depends on 20) The computer program product of claim 20, further comprising transmitting Inter-Carrier Interference (ICI) coefficient information corresponding to the tapering window to enable a receiving device to equalize a signal associated with the OFDM symbol by removing ICI in adjacent sub-carriers within the OFDM symbol by applying the ICI coefficient information. ### Claim 22 (depends on 19) The computer program product of claim 19, wherein reducing spectral leakage further comprises reducing transmission power for a set of adjacent sub-carriers within the OFDM symbol at an edge region within an inbound region of the OFDM symbol, wherein the edge region occupies frequencies adjacent to those occupied by the band edge. ### Claim 23 (depends on 19) The computer program product of claim 19, further comprising screening additional information to be provisioned to the band edge based on a distance over which the additional information is determined to be transmitted, wherein the additional information is selected for the band edge if the distance is less than a distance threshold set to insure communication of information in the band edge.