# US 11,121,734 B2 · Passive intermodulation PIM elimination method, apparatus, and base station > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,121,734 B2 - Document ID: US11121734B2 - Status: Granted - Kind: B2 - Application number: 16/369,336 - Filed: 2019-03-29 - Published: 2019-07-25 - Granted: 2021-09-14 - Earliest claimed: 2016-09-30 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Yong Jiang; Jia Lv; Yuxiang Xiao - Web page: https://patentgrep.com/patent/US11121734B2 ## CPC - H04B 1/123: {using adaptive balancing or compensation means (adaptive filter circuits and algorithms H03H)} - H04B 1/04: Circuits - H04B 1/1036: {with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters (H04B1/123 takes precedence; filter circuits H03H)} - H04B 1/109: {by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input} - H04L 27/2623: {Reduction thereof by clipping} - H04W 88/085: {Access point devices with remote components} - H04W 88/14: Backbone network devices - H04B 2001/0425: {with linearisation using predistortion} - H04B 2001/0433: {with linearisation using feedback} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A passive intermodulation elimination method, an apparatus, and a base station are disclosed. The method includes: receiving, by a network device, N pieces of backhauled information, where one piece of the backhauled information includes initial phase information of each carrier on one transmit channel, and N is an integer greater than or equal to 1; and eliminating, by the network device, a PIM of a received signal on a receive channel on the network device based on the N pieces of backhauled information. ## Claims ### Claim 1 A method of passive intermodulation (PIM) elimination, comprising: obtaining, by a network device, N pieces of backhauled information from a plurality of radio remote units (RRUs), wherein one piece of the N pieces of backhauled information comprises initial phase information of each carrier on one transmit channel, wherein at least one carrier is on the one transmit channel, wherein the one piece of the backhauled information is received by the network device on a receive channel of the network device, wherein the initial phase information of each carrier on the one transmit channel is determined when a numerically controlled oscillator (NCO) generates the at least one carrier on the one transmit channel, and wherein N is an integer greater than 1; and eliminating, by the network device, a PIM of a received signal on the receive channel on the network device based on the initial phase information of each carrier on the one transmit channel and a baseband signal. ### Claim 2 (depends on 1) The method according to claim 1, wherein the N pieces of backhauled information are N backhauled signals, and one of the backhauled signals is one single carrier signal on which frequency-shift has been performed and that is on a transmit channel, or one multi-carrier mixed signal on which multicarrier combining has been performed and that is on a transmit channel, and wherein after obtaining the single carrier signal on which frequency-shift is performed or the one multi-carrier mixed signal on which multicarrier combining is performed, the network device obtains a signal including the initial phase information of the at least one carrier. ### Claim 3 (depends on 2) The method according to claim 2, wherein at least one of the following processing may further be performed on the backhauled signals: crest factor reduction (CFR) processing, digital pre-distortion (DPD) processing, and radio frequency power amplification and feedback processing. ### Claim 4 (depends on 3) The method according to claim 3, wherein the network device is a baseband processing unit (BBU), and the method further comprises: sending, by M RRUs connected to the network device, the N pieces of backhauled information to the network device, wherein M is an integer greater than 1 and less than or equal to N. ### Claim 5 (depends on 3) The method according to claim 3, wherein the network device is an RRU, and the method further comprises: sending, by M RRUs other than the network device, the N pieces of backhauled information to the network device, wherein M is an integer greater than 1 and less than or equal to N; wherein the M RRUs and the network device are connected to a same baseband processing unit (BBU). ### Claim 6 (depends on 2) The method according to claim 2, wherein the network device is an RRU, and the method further comprises: sending, by M RRUs other than the network device, the N pieces of backhauled information to the network device, wherein M is an integer greater than 1 and less than or equal to N; wherein the M RRUs and the network device are connected to a same baseband processing unit (BBU). ### Claim 7 (depends on 2) The method according to claim 2, wherein the network device is an RRU, and the method further comprises: receiving, by a baseband processing unit (BBU) connected to the network device, the N pieces of backhauled information sent by M RRUs, wherein M is an integer greater than 1 and less than or equal to N; and sending, by the BBU, the N pieces of backhauled information to the network device. ### Claim 8 (depends on 2) The method according to claim 2, wherein the network device is a baseband processing unit (BBU), and the method further comprises: sending, by M RRUs connected to the network device, the N pieces of backhauled information to the network device, wherein M is an integer greater than 1 and less than or equal to N. ### Claim 9 (depends on 1) The method according to claim 1, wherein the network device is a baseband processing unit (BBU), and the method further comprises: sending, by M RRUs connected to the network device, the N pieces of backhauled information to the network device, wherein M is an integer greater than 1 and less than or equal to N. ### Claim 10 (depends on 9) The method according to claim 9, wherein that the RRUs send the backhauled information comprises: dividing, by the RRUs, at least one piece of to-be-sent backhauled information into K segments of information, and sending each of the K segments of information, wherein K is an integer greater than or equal to 1; or interleaving, by the RRUs, at least one piece of to-be-sent backhauled information, dividing the to-be-sent backhauled information into K segments of information, and sending each of the K segments of information, wherein K is an integer greater than or equal to 1. ### Claim 11 A network device, comprising: a receiver, configured to receive N pieces of backhauled information from a plurality of radio remote units (RRUs), wherein one piece of the N pieces of backhauled information comprises initial phase information of each carrier on one transmit channel, wherein at least one carrier is on the one transmit channel, wherein the one piece of the backhauled information is received on a receive channel of the network device, wherein the initial phase information of each carrier on the one transmit channel is determined when a numerically controlled oscillator (NCO) generates the at least one carrier on the one transmit channel, and wherein N is an integer greater than 1; and a processor, configured to eliminate a passive intermodulation (PIM) of a received signal on the receive channel on the network device based on the initial phase information of each carrier on the one transmit channel and a baseband signal. ### Claim 12 (depends on 11) The network device according to claim 11, wherein the N pieces of backhauled information are N backhauled signals, and the N backhauled signals are respectively single carrier signals on which frequency-shift has been performed and that are on N transmit channels, or multi-carrier mixed signals on which multicarrier combining has been performed and that are on N transmit channels, and wherein after obtaining the single carrier signal on which frequency-shift is performed or the one multi-carrier mixed signal on which multicarrier combining is performed, the network device obtains a signal including the initial phase information of the at least one carrier. ### Claim 13 (depends on 11) The network device according to claim 11, wherein the network device is a base band unit (BBU).