# US 10,375,658 B2 · Automatic gain control method and communications device in wireless local area network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,375,658 B2 - Document ID: US10375658B2 - Status: Granted - Kind: B2 - Application number: 15/594,192 - Filed: 2017-05-12 - Published: 2017-08-31 - Granted: 2019-08-06 - Earliest claimed: 2014-11-14 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Yalin Liu; Sheng Liu; Min Yan; Xin Xue - Web page: https://patentgrep.com/patent/US10375658B2 ## CPC - H04L 27/2613: {Structure of the reference signals} - H03G 3/3078: {Circuits generating control signals for digitally modulated signals} - H04L 27/2607: {Cyclic extensions} - H04L 27/2678: {using cyclostationarities, e.g. cyclic prefix or postfix} - H04L 69/22: Parsing or analysis of headers - H04W 52/52: using AGC [Automatic Gain Control] circuits or amplifiers - H04L 69/323: in the physical layer [OSI layer 1] - H04W 84/12: WLAN [Wireless Local Area Networks] - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H03G: CONTROL OF AMPLIFICATION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Embodiments disclose an automatic gain control method and a communications device in a wireless local area network. The method includes generating a physical layer packet, where the physical layer packet includes a high efficiency long training field, the high efficiency long training field includes N symbols, a length of a cyclic prefix (CP— of a first symbol in the N symbols is greater than or equal to a minimum length required by a receiver device to perform automatic gain control (AGC) estimation, and N is a positive integer. The method also includes sending the physical layer packet to the receiver device. ## Claims ### Claim 1 A method, comprising: generating, by a transmitter device, a physical layer packet comprising a high efficiency long training field, wherein the high efficiency long training field comprises N symbols, wherein a first length of a first cyclic prefix (CP) of a first symbol in the N symbols is greater than or equal to a minimum length for a receiver device to perform automatic gain control (AGC) estimation, wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is greater than a length of a CP of another symbol in the N symbols of the high efficiency long training field, and wherein N is a positive integer; and sending, by the transmitter device, the physical layer packet to the receiver device. ### Claim 2 (depends on 1) The method according to claim 1, wherein the physical layer packet does not comprise a high efficiency short training field. ### Claim 3 (depends on 1) The method according to claim 1, wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is equal to one of 1.6 microseconds, 2.4 microseconds, 3.2 microseconds, and 4.0 microseconds. ### Claim 4 (depends on 1) The method according to claim 1, wherein, when N is greater than or equal to 2, lengths of CPs of symbols from a second symbol to an Nth symbol in the N symbols of the high efficiency long training field is equal to one of 0.8 microseconds, 1.6 microseconds, 2.4 microseconds, and 3.2 microseconds. ### Claim 5 (depends on 1) The method according to claim 1, wherein sending the physical layer packet to the receiver device causes the receiver device to perform AGC estimation with the first CP of the first symbol in the N symbols and to perform fine AGC estimation with one or more remaining CPs corresponding to one or more remaining symbols in the N symbols. ### Claim 6 A method, comprising: receiving, by a receiver device, a physical layer packet from a sender device, wherein the physical layer packet comprises a high efficiency long training field, wherein the high efficiency long training field comprises N symbols, wherein a first length of a first cyclic prefix (CP) of a first symbol in the N symbols is greater than or equal to a minimum length for the receiver device to perform automatic gain control (AGC) estimation, wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is greater than a length of a CP of another symbol in the N symbols of the high efficiency long training field, and wherein N is a positive integer; and performing AGC estimation in accordance with the first CP of the first symbol in the N symbols of the high efficiency long training field. ### Claim 7 (depends on 6) The method according to claim 6, wherein the physical layer packet does not comprise a high efficiency short training field. ### Claim 8 (depends on 6) The method according to claim 6 wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is equal to one of 1.6 microseconds, 2.4 microseconds, 3.2 microseconds, and 4.0 microseconds. ### Claim 9 (depends on 6) The method according to claim 6, wherein, when N is greater than or equal to 2, lengths of CPs of symbols from a second symbol to an Nth symbol in the N symbols of the high efficiency long training field is equal to one of 0.8 microseconds, 1.6 microseconds, 2.4 microseconds, and 3.2 microseconds. ### Claim 10 (depends on 6) The method according to claim 6, further comprising: performing AGC estimation in accordance with remaining CPs corresponding to remaining symbols, other than the first symbol, in the N symbols. ### Claim 11 A communications device, comprising: a processor; and a non-transitory computer readable storage medium storing a program for execution by the processor, the program including instructions to: generate a physical layer packet comprising a high efficiency long training field, wherein the high efficiency long training field comprises N symbols, wherein a first length of a first CP of a first symbol in the N symbols is greater than or equal to a minimum length for a receiver device to perform automatic gain control (AGC) estimation, wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is greater than a length of a CP of another symbol in the N symbols of the high efficiency long training field, and wherein N is a positive integer; and send the physical layer packet to the receiver device. ### Claim 12 (depends on 11) The communications device according to claim 11, wherein the physical layer packet does not comprise a high efficiency short training field. ### Claim 13 (depends on 11) The communications device according to claim 11, wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is equal to one of 1.6 microseconds, 2.4 microseconds, 3.2 microseconds, and 4.0 microseconds. ### Claim 14 (depends on 11) The communications device according to claim 11, wherein, when N is greater than or equal to 2, a length of a CP of symbols from a second symbol to an Nth symbol in the N symbols of the high efficiency long training field is equal to one of 0.8 microseconds, 1.6 microseconds, 2.4 microseconds, and 3.2 microseconds. ### Claim 15 (depends on 11) The communications device according to claim 11, wherein the instructions to send the physical layer packet to the receiver device cause the receiver device to perform AGC estimation with the first CP of the first symbol in the N symbols and to perform fine AGC estimation with one or more remaining CPs corresponding to one or more remaining symbols in the N symbols. ### Claim 16 A communications device, comprising: a processor; and a non-transitory computer readable storage medium storing a program for execution by the processor, the program including instructions to: receive a physical layer packet from a sender device, wherein the physical layer packet comprises a high efficiency long training field, wherein the high efficiency long training field comprises N symbols, wherein a first length of a first cyclic prefix (CP) of a first symbol in the N symbols is greater than or equal to a minimum length for a receiver device to perform automatic gain control (AGC) estimation, wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is greater than a length of a CP of another symbol in the N symbols of the high efficiency long training field, and wherein N is a positive integer; and perform AGC estimation in accordance with the first CP of the first symbol in the N symbols of the high efficiency long training field. ### Claim 17 (depends on 16) The communications device according to claim 16, wherein the physical layer packet does not comprise a high efficiency short training field. ### Claim 18 (depends on 16) The communications device according to claim 16, wherein the first length of the first CP of the first symbol in the N symbols of the high efficiency long training field is equal to one of 1.6 microseconds, 2.4 microseconds, 3.2 microseconds, and 4.0 microseconds. ### Claim 19 (depends on 16) The communications device according to claim 16, wherein, when N is greater than or equal to 2, a length of a CP of symbols from a second symbol to an Nth symbol in the N symbols of the high efficiency long training field is equal to one of 0.8 microseconds, 1.6 microseconds, 2.4 microseconds, and 3.2 microseconds. ### Claim 20 (depends on 16) The communications device according to claim 16, wherein the program further includes instructions to: perform AGC estimation in accordance with remaining CPs corresponding to remaining symbols, other than the first symbol, in the N symbols.