# US 2025/0096979 A1 · Approaches for backscattering > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0096979 A1 - Document ID: US20250096979A1 - Status: Published application - Kind: A1 - Application number: 18/727,163 - Filed: 2022-01-14 - Published: 2025-03-20 - Earliest claimed: 2022-01-14 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Miguel LOPEZ; Guido Roland HIERTZ; Leif WILHELMSSON - Web page: https://patentgrep.com/patent/US20250096979A1 ## CPC - H04B 5/45: Transponders - H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - H04B 5/77: for interrogation - H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Methods, signal packets, orthogonal frequency division multiplexing (OFDM) transmitters, backscattering devices and corresponding computer program products are disclosed. According to one aspect, a signal packet is provided for transmission by an OFDM transmitter of to illuminate a backscatter device. The signal packet includes an initial portion to trigger circuitry of the backscatter device for operation, and to transfer energy to the backscatter device. The signal packet includes a data carrying portion providing control information. The data carrying portion includes to the backscatter device regarding backscatter transmission, and an illuminating portion to cause backscatter transmission within a duration of the illuminating portion in accordance with the control information. Also disclosed are a method for an OFDM transmitter and a method for a backscatter device. ## Claims ### Claim 1 A method for an orthogonal frequency division multiplex (OFDM) transmitter, the method comprising: transmitting a signal packet for illumination of a backscatter device, the signal packet comprising: an initial portion configured to trigger circuitry of the backscatter device for operation, and configured to transfer energy to the backscatter device; at least one data carrying portion configured to provide control information to the backscatter device regarding backscatter transmission; and at least one illuminating portion configured to cause backscatter transmission by the backscatter device within a duration of the illuminating portion and in accordance with the provided control information. ### Claim at position 2 2-8. (canceled) ### Claim 9 (depends on 1) The method of claim 1, wherein at least one illuminating portion comprises at least one continuously active sub-carrier. ### Claim 10 (depends on 1) The method of claim 1, wherein at least one illuminating portion extends only over a subset of OFDM signal frequency resources. ### Claim 11 (canceled) ### Claim 12 (depends on 1) The method of claim 1, wherein the control information provided by the data carrying portion includes a frequency indicator for the backscatter transmission. ### Claim 13 (depends on 12) The method of claim 12, wherein the frequency indicator for the backscatter transmission is configured to cause the backscatter transmission and a corresponding illuminating portion to be non-overlapping in frequency. ### Claim 14 (depends on 12) The method of claim 12, wherein the frequency indicator for the backscatter transmission is configured to cause the backscatter transmission to coincide with at least one orthogonal frequency division multiplex (OFDM) signal sub-carrier. ### Claim 15 (canceled) ### Claim 16 (canceled) ### Claim 17 (depends on 1) The method of claim 1, wherein the control information provided by the data carrying portion specifies at least one timing parameter for a transmission instance of the backscatter transmission. ### Claim 18 (depends on 17) The method of claim 17, wherein the at least one timing parameter for a transmission instance of the backscatter transmission includes at least one of a transmission instance start time, a transmission instance end time and a transmission instance duration. ### Claim 19 (depends on 17) The method of claim 17, wherein the at least one timing parameter for a transmission instance of the backscatter transmission defines the transmission instance as coinciding with at least one OFDM symbol. ### Claim at position 14 20-23. (canceled) ### Claim 24 A method for a backscatter device, the method comprising: receiving a signal packet from an orthogonal frequency division multiplex (OFDM) transmitter, the signal packet comprising: an initial portion configured to trigger circuitry of the backscatter device for operation, and configured to transfer energy to the backscatter device; at least one data carrying portion configured to provide control information to the backscatter device regarding backscatter transmission; and at least one illuminating portion configured to cause backscatter transmission by the backscatter device within a duration of the illuminating portion and in accordance with the provided control information; and harvesting energy from at least the initial portion. ### Claim 25 (depends on 24) The method of claim 24, wherein one or both of the at least one illuminating portion and the data carrying portion is further configured to transfer energy to the backscatter device. ### Claim 26 (canceled) ### Claim 27 (depends on 24) The method of claim 24, further comprising performing time synchronization based on time synchronization information comprised in the control information provided by the data carrying portion. ### Claim 28 (depends on 24) The method of claim 24, further comprising performing backscatter transmission within the duration of the illuminating portion. ### Claim 29 (depends on 28) The method of claim 28, wherein the backscatter transmission is performed using at least one of frequency shift keying (FSK), on-off keying (OOK), and Manchester coding (MC). ### Claim 30 (depends on 28) The method of claim 28, wherein the backscatter transmission is performed in accordance with a frequency indicator included in the control information provided by the data carrying portion. ### Claim at position 22 31-34. (canceled) ### Claim 35 (depends on 1) The method of claim 1, wherein the OFDM transmitter is an OFDM transceiver configured for simultaneous transmission and reception in a same channel, wherein the simultaneous transmission and reception use different OFDM signal frequency resources within the channel. ### Claim at position 24 36-59. (canceled) ### Claim 60 An apparatus for an orthogonal frequency division multiplex (OFDM) transmitter, the apparatus comprising: controlling circuitry configured to cause transmission of a signal packet for illumination of a backscatter device, the signal packet comprising: an initial portion configured to trigger circuitry of the backscatter device for operation, and configured to transfer energy to the backscatter device; at least one data carrying portion configured to provide control information to the backscatter device regarding backscatter transmission; and at least one illuminating portion configured to cause backscatter transmission by the backscatter device within a duration of the illuminating portion and in accordance with the provided control information. ### Claim 61 (depends on 60) The apparatus of claim 60, wherein at least one illuminating portion comprises at least one continuously active sub-carrier. ### Claim 62 (depends on 60) The apparatus of claim 60, wherein the apparatus is comprised on an orthogonal frequency division multiplex (OFDM) transmitter. ### Claim at position 28 63-66. (canceled) ### Claim 67 An apparatus for a backscatter device, the apparatus comprising controlling circuitry configured to: cause reception of a signal packet from an orthogonal frequency division multiplex (OFDM) transmitter, the signal packet comprising: an initial portion configured to trigger circuitry of the backscatter device for operation, and configured to transfer energy to the backscatter device; at least one data carrying portion configured to provide control information to the backscatter device regarding backscatter transmission; and at least one illuminating portion configured to cause backscatter transmission by the backscatter device within a duration of the illuminating portion and in accordance with the provided control information; and harvest energy from at least the initial portion. ### Claim at position 30 68-70. (canceled)