# US 10,122,508 B2 · Method and apparatus for configuring a long training field in a wireless local area network system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,508 B2 - Document ID: US10122508B2 - Status: Granted - Kind: B2 - Application number: 15/224,386 - Filed: 2016-07-29 - Published: 2017-02-02 - Granted: 2018-11-06 - Earliest claimed: 2015-07-31 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Eunsung Park; Jinsoo Choi; Dongguk Lim; Hangyu Cho - Web page: https://patentgrep.com/patent/US10122508B2 ## CPC - 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)} - H04L 5/0064: {Rate requirement of the data, e.g. scalable bandwidth, data priority} - H04L 5/0091: {Signalling for the administration of the divided path, e.g. signalling of configuration information} - H04L 27/2602: {Signal structure} - H04L 27/2613: {Structure of the reference signals} - H04L 5/0023: {Time-frequency-space} - H04L 5/0032: {Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation} - H04L 27/26025: {Numerology, i.e. varying one or more of symbol duration, subcarrier spacing, Fourier transform size, sampling rate or down-clocking (allocating sub-channels of the transmission path H04L5/003)} - H04L 27/26035: {Maintenance of orthogonality, e.g. for signals exchanged between cells or users, or by using covering codes or sequences (using different training sequence per antenna H04B7/0684; code allocation H04J13/16)} - H04L 27/26132: {using repetition} - H04L 27/26136: {Pilot sequence conveying additional information} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Proposed herein is a LTF sequence that is used in a wireless LAN system. The proposed LTF sequence may correspond to a sequence for a second frequency band of a second wireless LAN system. The proposed sequence may be generated through a LTF sequence that is used in a first wireless LAN system, which is different from the second wireless LAN system. The LTF sequence of the first wireless LAN system may correspond to a sequence for a first frequency band, which is different from the second frequency band. A length of an IDFT/DFT period and a bandwidth of a transmission frequency that are applied to the LTF sequence of the first wireless LAN system are different from a length of an IDFT/DFT period and a bandwidth of a transmission frequency that are applied to the LTF sequence of the second wireless LAN system. ## Claims ### Claim 1 A method for configuring a Long Training Field (LTF) in a wireless LAN system, comprising: configuring, by a transmitting apparatus, a LTF for a second frequency band of a second wireless LAN system by using a LTF sequence for a first frequency band of a first wireless LAN system; and transmitting, by the transmitting apparatus, the LTF for the second frequency band through a Physical layer Protocol Data Unit (PPDU) including a first field area and a second field area, wherein the second field area includes the LTF and a data field for the second frequency band, wherein an Inverse Discrete Fourier Transform (IDFT)/Discrete Fourier Transform (DFT) period being applied to each symbol of the first field area is shorter than an IDFT/DFT period being applied to each symbol of the second field area, and wherein a bandwidth of the first frequency band is larger than a bandwidth of the second frequency band. ### Claim 2 (depends on 1) The method of claim 1, wherein the LTF sequence for the first frequency band corresponds to a Very High Throughput (VHT) LTF sequence, wherein the LTF for the second frequency band corresponds to a High Efficiency (HE) LTF, and wherein the PPDU corresponds to a HE PPDU. ### Claim 3 (depends on 1) The method of claim 1, wherein the bandwidth of the first frequency band is equal to 80 MHz, and wherein the bandwidth of the second frequency band is equal to 20 MHz. ### Claim 4 (depends on 1) The method of claim 1, wherein the IDFT/DFT period being applied to each symbol of the first field area is 2 times or 4 times shorter than the IDFT/DFT period being applied to each symbol of the second field area. ### Claim 5 (depends on 1) The method of claim 1, wherein, in case the IDFT/DFT period being applied to each symbol of the first field area is 4 times shorter than the IDFT/DFT period being applied to each symbol of the second field area, and in case the bandwidth of the first frequency band is equal to 80 MHz and the bandwidth of the second frequency band is equal to 20 MHz, the LTF for the second frequency band is configured by using a LTF sequence for the first frequency band. ### Claim 6 (depends on 5) The method of claim 5, wherein, in case the IDFT/DFT period being applied to each symbol of the first field area is 4 times shorter than the IDFT/DFT period being applied to each symbol of the second field area, and in case the bandwidth of the first frequency band is equal to 80 MHz and the bandwidth of the second frequency band is equal to 40 MHz, the LTF for the second frequency band is configured by repeating the LTF sequence for the first frequency band. ### Claim 7 A transmitting apparatus for configuring a Long Training Field (LTF) in a wireless LAN system, comprising: a radio frequency unit (RF unit) configured to transmit or receive radio signals; and a processor configured to control the RF unit, wherein the processor: configures a LTF for a second frequency band of a second wireless LAN system by using a LTF sequence for a first frequency band of a first wireless LAN system, and transmits the LTF for the second frequency band through a Physical layer Protocol Data Unit (PPDU) including a first field area and a second field area, wherein the second field area includes the LTF and a data field for the second frequency band, wherein an Inverse Discrete Fourier Transform (IDFT)/Discrete Fourier Transform (DFT) period being applied to each symbol of the first field area is shorter than an IDFT/DFT period being applied to each symbol of the second field area, and wherein a bandwidth of the first frequency band is larger than a bandwidth of the second frequency band.