CN110402551B - 使用用信号通知的动态参数的rlm监测 - Google Patents

使用用信号通知的动态参数的rlm监测 Download PDF

Info

Publication number
CN110402551B
CN110402551B CN201880018060.2A CN201880018060A CN110402551B CN 110402551 B CN110402551 B CN 110402551B CN 201880018060 A CN201880018060 A CN 201880018060A CN 110402551 B CN110402551 B CN 110402551B
Authority
CN
China
Prior art keywords
pdcch
csi
adjustment parameter
radio link
base station
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201880018060.2A
Other languages
English (en)
Chinese (zh)
Other versions
CN110402551A (zh
Inventor
M·P·约翰威尔逊
骆涛
S·阿卡拉卡兰
S·纳加拉贾
H·李
张晓霞
X·F·王
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Qualcomm Inc
Original Assignee
Qualcomm Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Qualcomm Inc filed Critical Qualcomm Inc
Publication of CN110402551A publication Critical patent/CN110402551A/zh
Application granted granted Critical
Publication of CN110402551B publication Critical patent/CN110402551B/zh
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/20—Control channels or signalling for resource management
    • H04W72/23—Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/20—Monitoring; Testing of receivers
    • H04B17/21—Monitoring; Testing of receivers for calibration; for correcting measurements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/309—Measuring or estimating channel quality parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0014—Three-dimensional division
    • H04L5/0023—Time-frequency-space
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signalling, i.e. of overhead other than pilot signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/046—Wireless resource allocation based on the type of the allocated resource the resource being in the space domain, e.g. beams
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H04L5/005—Allocation of pilot signals, i.e. of signals known to the receiver of common pilots, i.e. pilots destined for multiple users or terminals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H04L5/0051—Allocation of pilot signals, i.e. of signals known to the receiver of dedicated pilots, i.e. pilots destined for a single user or terminal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/08—Testing, supervising or monitoring using real traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/20—Manipulation of established connections
    • H04W76/27—Transitions between radio resource control [RRC] states

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Quality & Reliability (AREA)
  • Power Engineering (AREA)
  • Mobile Radio Communication Systems (AREA)
CN201880018060.2A 2017-03-17 2018-02-14 使用用信号通知的动态参数的rlm监测 Active CN110402551B (zh)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US201762473238P 2017-03-17 2017-03-17
US62/473,238 2017-03-17
US15/895,839 US11082105B2 (en) 2017-03-17 2018-02-13 RLM monitoring using signaled dynamic parameter
US15/895,839 2018-02-13
PCT/US2018/018221 WO2018169636A1 (en) 2017-03-17 2018-02-14 Rlm monitoring using signaled dynamic parameter

Publications (2)

Publication Number Publication Date
CN110402551A CN110402551A (zh) 2019-11-01
CN110402551B true CN110402551B (zh) 2022-03-22

Family

ID=63520360

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201880018060.2A Active CN110402551B (zh) 2017-03-17 2018-02-14 使用用信号通知的动态参数的rlm监测

Country Status (8)

Country Link
US (1) US11082105B2 (https=)
EP (1) EP3596851A1 (https=)
JP (1) JP7050799B2 (https=)
KR (1) KR102630887B1 (https=)
CN (1) CN110402551B (https=)
BR (1) BR112019019032A2 (https=)
SG (1) SG11201907097XA (https=)
WO (1) WO2018169636A1 (https=)

Families Citing this family (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107769826A (zh) * 2016-08-19 2018-03-06 索尼公司 无线通信系统中的电子设备和方法以及无线通信系统
JP6808035B2 (ja) * 2016-11-04 2021-01-06 テレフオンアクチーボラゲット エルエム エリクソン（パブル） 無線リンク監視のための方法およびデバイス
KR101921710B1 (ko) * 2017-01-06 2019-02-13 엘지전자 주식회사 무선 통신 시스템에서의 참조 신호 수신 방법 및 이를 위한 장치
RU2732078C1 (ru) * 2017-04-25 2020-09-11 Гуандун Оппо Мобайл Телекоммьюникейшнс Корп., Лтд. Способ и устройство обработки сигналов
KR20190138873A (ko) 2017-05-05 2019-12-16 텔레폰악티에볼라겟엘엠에릭슨(펍) 무선 통신 네트워크에서의 사용자 장치, 기지국 및 방법
US10644777B2 (en) * 2017-05-05 2020-05-05 Huawei Technologies Co., Ltd. Channel state information reference signal (CSI-RS) for layer-3 (L3) mobility
WO2018201438A1 (en) * 2017-05-05 2018-11-08 Qualcomm Incorporated Communication scheme for small cyclic delay diversity reference signals
US10897287B2 (en) * 2017-05-15 2021-01-19 Futurewei Technologies, Inc. System and method for spatial quasi-co-location (SQCL) similar angle precoding (SAP)
CN114980192B (zh) * 2017-08-07 2025-11-28 维沃移动通信有限公司 一种无线链路监听的方法、配置方法、终端及网络设备
WO2019097457A1 (en) * 2017-11-16 2019-05-23 Telefonaktiebolaget Lm Ericsson (Publ) Method for performing radio link monitoring
US11191060B2 (en) * 2018-03-15 2021-11-30 Sprint Communications Company L.P. Dynamic wireless network architecture to serve uplink-centric and downlink-centric user applications
WO2020011330A1 (en) * 2018-07-07 2020-01-16 Telefonaktiebolaget Lm Ericsson (Publ) Methods and apparatus relating to a wireless communication network that utilises beamforming
CN114900839B (zh) 2018-09-28 2025-07-15 华为技术有限公司 传输信息的方法和装置
US10848996B2 (en) * 2018-10-17 2020-11-24 Apple Inc. Adaptive procedures for measurement of wireless channel conditions
CN111148242B (zh) * 2018-11-05 2022-07-29 华为技术有限公司 信息传输方法及装置
US11962539B2 (en) * 2018-11-08 2024-04-16 Apple Inc. Techniques in adaptive in-sync and out-of-sync classification based on channel parameter estimation in new radio
US11425555B2 (en) * 2018-12-05 2022-08-23 Qualcomm Incorporated UE assistance information for power saving configuration
CN111435853B (zh) * 2019-02-02 2023-07-14 维沃移动通信有限公司 Csi参数的指示方法和设备
CN111130741B (zh) 2019-02-15 2022-05-17 华为技术有限公司 通信方法和设备
CN114616762A (zh) * 2019-10-25 2022-06-10 Oppo广东移动通信有限公司 用于传输信道状态信息的方法和设备
CN113810920B (zh) * 2020-06-11 2025-02-07 中兴通讯股份有限公司 波束训练方法、网络设备、终端、系统和存储介质
US20220104044A1 (en) * 2020-09-25 2022-03-31 Mediatek Inc. Efficient RLM/BFD Measurement in Connected Mode
WO2022099660A1 (zh) * 2020-11-13 2022-05-19 华为技术有限公司 一种波束切换的方法及装置

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103155473A (zh) * 2010-08-16 2013-06-12 高通股份有限公司 针对中继物理下行链路控制信道（r-pdcch）的交织
CN103200684A (zh) * 2012-01-09 2013-07-10 华为技术有限公司 一种控制信道传输、接收方法及基站、用户设备
GB2507570A (en) * 2012-11-05 2014-05-07 Broadcom Corp Providing enhanced Radio Link Monitoring
WO2014193070A1 (en) * 2013-05-30 2014-12-04 Lg Electronics Inc. Reference signals extension for massive mimo system
WO2016021880A1 (ko) * 2014-08-04 2016-02-11 엘지전자(주) 무선 통신 시스템에서 comp 동작을 위한 시그널링 방법 및 이를 위한 장치
WO2016163645A1 (ko) * 2015-04-10 2016-10-13 엘지전자 주식회사 Pdsch 수신 방법 및 무선 기기
WO2016163842A1 (ko) * 2015-04-10 2016-10-13 엘지전자 (주) 무선 통신 시스템에서 채널 상태 정보를 보고하기 위한 방법 및 이를 위한 장치
CN106465169A (zh) * 2014-03-14 2017-02-22 诺基亚通信公司 休眠小区rrm测量报告

Family Cites Families (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8611941B2 (en) * 2008-08-18 2013-12-17 Qualcomm Incorporated System and method for processing power control commands in a wireless communication system
KR101763750B1 (ko) 2011-06-17 2017-08-01 삼성전자 주식회사 협력 통신을 위한 피드백 송수신 방법 및 장치
CN107104781B (zh) * 2012-02-11 2020-06-05 Lg电子株式会社 接收和发送下行链路数据信道的方法及设备
US8995366B2 (en) 2012-03-23 2015-03-31 Google Technology Holdings LLC Radio link monitoring in a wireless communication device for a enhanced control channel
US9198070B2 (en) 2012-05-14 2015-11-24 Google Technology Holdings LLC Radio link monitoring in a wireless communication device
US10897341B2 (en) 2012-07-18 2021-01-19 Nokia Solutions And Networks Oy Detecting intermodulation in broadband communication affecting receiver sensitivity
US9203576B2 (en) 2012-08-03 2015-12-01 Telefonaktiebolaget L M Ericsson (Publ) Quasi co-located antenna ports for channel estimation
KR102186240B1 (ko) * 2012-08-31 2020-12-03 엘지전자 주식회사 무선 통신 시스템에서 하향링크 신호 수신 방법 및 장치
WO2014054901A1 (ko) * 2012-10-04 2014-04-10 엘지전자 주식회사 무선 통신 시스템에서 안테나 포트 관계를 고려한 하향링크 신호 송수신 방법 및 장치
US9531448B2 (en) * 2013-01-17 2016-12-27 Telefonaktiebolaget Lm Ericsson (Publ) Autonomous quasi co-location status redefinition by receiver in coordinated multipoint downlink
KR102202333B1 (ko) 2013-01-26 2021-01-13 엘지전자 주식회사 무선 통신 시스템에서 단말이 하향링크 제어 정보를 수신하는 방법 및 이를 위한 장치
US9521602B2 (en) * 2013-08-09 2016-12-13 Qualcomm Incorporated Method and apparatus for management of high frequency communications in a low frequency wireless network
WO2015114562A1 (en) * 2014-01-30 2015-08-06 Telefonaktiebolaget L M Ericsson (Publ) Cell id expansion and hierarchical cell id structures
WO2015115991A1 (en) * 2014-01-31 2015-08-06 Telefonaktiebolaget L M Ericsson (Publ) Network assisted interference mitigation
WO2015166846A1 (ja) 2014-04-28 2015-11-05 シャープ株式会社 端末装置、基地局装置および通信方法
US10368363B2 (en) * 2015-04-16 2019-07-30 Lg Electronics Inc. Uplink data transmission method in wireless communication system and device therefor
EP3289803B1 (en) * 2015-04-30 2019-06-12 Telefonaktiebolaget LM Ericsson (PUBL) Relaxed measurement reporting with control plane dual connectivity
US9832747B2 (en) * 2015-09-21 2017-11-28 Intel IP Corporation Mobile terminal device, mobile processing circuit and method of processing signals
US9716582B2 (en) * 2015-09-30 2017-07-25 Rambus Inc. Deserialized dual-loop clock radio and data recovery circuit
US10313168B2 (en) * 2015-12-11 2019-06-04 Lg Electronics Inc. Method and user equipment for receiving downlink channel, and method and base station for transmitting downlink channel
US11129152B2 (en) * 2016-02-04 2021-09-21 Lg Electronics Inc. Method and user equipment for receiving dowlink control information, and method and base station for transmitting dowlink control information
CN113630167B (zh) * 2016-03-03 2024-01-26 交互数字专利控股公司 用于波束成形系统内的波束控制的方法及设备
WO2018017840A1 (en) * 2016-07-20 2018-01-25 Convida Wireless, Llc Mobility for radio devices using beamforming and selection
US11005637B2 (en) * 2016-07-21 2021-05-11 Lg Electronics Inc. Method and user equipment for receiving downlink channel, and method and base station for transmitting downlink channel
WO2018030756A1 (ko) * 2016-08-08 2018-02-15 엘지전자 주식회사 채널 상태 정보 전송 방법 및 사용자기기와, 채널 상태 정보 수신 방법 및 기지국
WO2018083624A1 (en) * 2016-11-04 2018-05-11 Telefonaktiebolaget Lm Ericsson (Publ) Methods and apparatuses for handling beam failure
US10334488B2 (en) * 2016-12-27 2019-06-25 T-Mobile Usa, Inc. LTE cell level network coverage and performance auto optimization
US10432441B2 (en) * 2017-02-06 2019-10-01 Samsung Electronics Co., Ltd. Transmission structures and formats for DL control channels
EP4243325B1 (en) * 2017-11-15 2026-02-18 InterDigital Patent Holdings, Inc. Beam management in a wireless network
US10841149B2 (en) * 2018-04-14 2020-11-17 Qualcomm Incorporated Beam failure recovery in connection with switching BWP

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103155473A (zh) * 2010-08-16 2013-06-12 高通股份有限公司 针对中继物理下行链路控制信道（r-pdcch）的交织
CN103200684A (zh) * 2012-01-09 2013-07-10 华为技术有限公司 一种控制信道传输、接收方法及基站、用户设备
GB2507570A (en) * 2012-11-05 2014-05-07 Broadcom Corp Providing enhanced Radio Link Monitoring
WO2014068535A2 (en) * 2012-11-05 2014-05-08 Renesas Mobile Corporation Method and apparatus for providing enhanced radio link monitoring
WO2014193070A1 (en) * 2013-05-30 2014-12-04 Lg Electronics Inc. Reference signals extension for massive mimo system
CN106465169A (zh) * 2014-03-14 2017-02-22 诺基亚通信公司 休眠小区rrm测量报告
WO2016021880A1 (ko) * 2014-08-04 2016-02-11 엘지전자(주) 무선 통신 시스템에서 comp 동작을 위한 시그널링 방법 및 이를 위한 장치
WO2016163645A1 (ko) * 2015-04-10 2016-10-13 엘지전자 주식회사 Pdsch 수신 방법 및 무선 기기
WO2016163842A1 (ko) * 2015-04-10 2016-10-13 엘지전자 (주) 무선 통신 시스템에서 채널 상태 정보를 보고하기 위한 방법 및 이를 위한 장치

Also Published As

Publication number Publication date
KR102630887B1 (ko) 2024-01-29
SG11201907097XA (en) 2019-09-27
WO2018169636A1 (en) 2018-09-20
KR20190126872A (ko) 2019-11-12
JP7050799B2 (ja) 2022-04-08
US20180269950A1 (en) 2018-09-20
BR112019019032A2 (pt) 2020-04-22
EP3596851A1 (en) 2020-01-22
JP2020511075A (ja) 2020-04-09
US11082105B2 (en) 2021-08-03
CN110402551A (zh) 2019-11-01

Similar Documents

Publication Publication Date Title
CN110402551B (zh) 使用用信号通知的动态参数的rlm监测
EP3632162B1 (en) Conditional reference signal transmission and measurement
US10412702B2 (en) Declaring quasi co-location among multiple antenna ports
CN110463326B (zh) 窄带通信中的动态带宽配置
CN109196923B (zh) 同步信道的时分复用
CN109314570B (zh) 用于同步信道的时分复用的方法、装置和计算机可读介质
CN109076592B (zh) 用于波束调整请求的系统和方法
CN109196795B (zh) 同步信道的时分复用
CN111510273B (zh) 在控制区域中对数据进行复用时的mcs/秩调整
CN115278801A (zh) 在波束改变指令接收的失败期间的回退波束选择规程
CN109937554B (zh) 基于信道质量指示符的与物理下行链路控制信道相关联的搜索空间
CN113852454A (zh) 同步信道的时分复用
WO2020257081A1 (en) Methods and apparatus to facilitate dual stage channel state information reference signal (csi-rs) selection for csi feedback
US20230180158A1 (en) Lte-nr relative timing indication
HK40015828B (en) Rlm monitoring using signaled dynamic parameter
HK40015828A (en) Rlm monitoring using signaled dynamic parameter
HK40006060A (en) Declaring quasi co-location among multiple antenna ports

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
REG Reference to a national code

Ref country code: HK

Ref legal event code: DE

Ref document number: 40015828

Country of ref document: HK

GR01 Patent grant
GR01 Patent grant