Nothing Special   »   [go: up one dir, main page]

FI20010079A - Paikannusmenetelmä ja radiojärjestelmä - Google Patents

Paikannusmenetelmä ja radiojärjestelmä Download PDF

Info

Publication number
FI20010079A
FI20010079A FI20010079A FI20010079A FI20010079A FI 20010079 A FI20010079 A FI 20010079A FI 20010079 A FI20010079 A FI 20010079A FI 20010079 A FI20010079 A FI 20010079A FI 20010079 A FI20010079 A FI 20010079A
Authority
FI
Finland
Prior art keywords
radio system
location procedure
procedure
location
radio
Prior art date
Application number
FI20010079A
Other languages
English (en)
Swedish (sv)
Other versions
FI20010079A0 (fi
Inventor
Ari Hottinen
Original Assignee
Nokia Corp
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 Nokia Corp filed Critical Nokia Corp
Priority to FI20010079A priority Critical patent/FI20010079A/fi
Publication of FI20010079A0 publication Critical patent/FI20010079A0/fi
Priority to PCT/FI2002/000022 priority patent/WO2002054850A2/en
Priority to AU2002226447A priority patent/AU2002226447A1/en
Priority to EP02716113A priority patent/EP1362492A2/en
Publication of FI20010079A publication Critical patent/FI20010079A/fi
Priority to US10/616,292 priority patent/US7376428B2/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G01S3/38—Systems for determining direction or deviation from predetermined direction using adjustment of real or effective orientation of directivity characteristic of an antenna or an antenna system to give a desired condition of signal derived from that antenna or antenna system, e.g. to give a maximum or minimum signal
    • G01S3/40—Systems for determining direction or deviation from predetermined direction using adjustment of real or effective orientation of directivity characteristic of an antenna or an antenna system to give a desired condition of signal derived from that antenna or antenna system, e.g. to give a maximum or minimum signal adjusting orientation of a single directivity characteristic to produce maximum or minimum signal, e.g. rotatable loop antenna or equivalent goniometer system
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/0226—Transmitters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0252—Radio frequency fingerprinting
    • G01S5/02521—Radio frequency fingerprinting using a radio-map
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/12—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
    • 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
    • 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
    • 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
    • H04B7/0667—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 delayed versions of same signal
    • 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
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/086—Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)
FI20010079A 2001-01-12 2001-01-12 Paikannusmenetelmä ja radiojärjestelmä FI20010079A (fi)

Priority Applications (5)

Application Number Priority Date Filing Date Title
FI20010079A FI20010079A (fi) 2001-01-12 2001-01-12 Paikannusmenetelmä ja radiojärjestelmä
PCT/FI2002/000022 WO2002054850A2 (en) 2001-01-12 2002-01-10 Positioning method and radio system
AU2002226447A AU2002226447A1 (en) 2001-01-12 2002-01-10 Positioning method and radio system
EP02716113A EP1362492A2 (en) 2001-01-12 2002-01-10 Positioning method and radio system
US10/616,292 US7376428B2 (en) 2001-01-12 2003-07-10 Positioning method and radio system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FI20010079A FI20010079A (fi) 2001-01-12 2001-01-12 Paikannusmenetelmä ja radiojärjestelmä

Publications (2)

Publication Number Publication Date
FI20010079A0 FI20010079A0 (fi) 2001-01-12
FI20010079A true FI20010079A (fi) 2002-07-13

Family

ID=8559995

Family Applications (1)

Application Number Title Priority Date Filing Date
FI20010079A FI20010079A (fi) 2001-01-12 2001-01-12 Paikannusmenetelmä ja radiojärjestelmä

Country Status (5)

Country Link
US (1) US7376428B2 (fi)
EP (1) EP1362492A2 (fi)
AU (1) AU2002226447A1 (fi)
FI (1) FI20010079A (fi)
WO (1) WO2002054850A2 (fi)

Families Citing this family (53)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI108588B (fi) * 1998-12-15 2002-02-15 Nokia Corp Menetelmä ja radiojärjestelmä digitaalisen signaalin siirtoon
US7336626B1 (en) * 2001-09-28 2008-02-26 Arraycomm, Inc Operating time division duplex (TDD) wireless systems in paired spectrum (FDD) allocations
US20040203420A1 (en) * 2002-04-10 2004-10-14 Rick Roland R. Method and apparatus for calculating a representative measurement from multiple data measurements
US20040166881A1 (en) * 2003-02-06 2004-08-26 Farchmin David Walter Phased array wireless location method and apparatus
US7385914B2 (en) 2003-10-08 2008-06-10 Atheros Communications, Inc. Apparatus and method of multiple antenna transmitter beamforming of high data rate wideband packetized wireless communication signals
US7564914B2 (en) * 2004-12-14 2009-07-21 Broadcom Corporation Method and system for frame formats for MIMO channel measurement exchange
DE102004059980A1 (de) 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Mischer zum Mischen eines Signals und Verfahren zum Mischen eines Signals
DE102004059941A1 (de) 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Bestimmen eines Eintreffzeitpunktes einer Empfangsfolge
DE102004059940A1 (de) * 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Signalkonvertierer zum Konvertieren eines Startsignals in ein Endsignal und Verfahren zum Konvertieren eines Startsignals in ein Endsignal
DE102004059957A1 (de) * 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Synchronisationsvorrichtung und Vorrichtung zum Erzeugen eines Synchronisationssignals
DE102004059958B4 (de) * 2004-12-13 2007-10-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Bestimmen eines Korrelationswertes
DE102004059946B4 (de) 2004-12-13 2008-10-02 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Ermitteln eines Korrelationsmaximums
EP1871123B1 (en) * 2005-04-05 2011-08-10 Panasonic Corporation Wireless network system in a vehicle
US8265657B2 (en) 2006-05-18 2012-09-11 Samsung Electronics Co., Ltd. Method and system for device discovery in a wireless video area network
ES2797393T3 (es) 2007-05-01 2020-12-02 Qualcomm Inc Ubicación de la posición para sistemas de comunicación inalámbrica
US7990332B1 (en) 2007-05-16 2011-08-02 At&T Intellectual Property I, L.P. Multi-directional receiving antenna array
US9119026B2 (en) 2007-05-18 2015-08-25 Qualcomm Incorporated Enhanced pilot signal
US8412227B2 (en) 2007-05-18 2013-04-02 Qualcomm Incorporated Positioning using enhanced pilot signal
US8265047B2 (en) * 2007-09-13 2012-09-11 Samsung Electronics Co., Ltd. System and method for device discovery in a wireless network of devices having directional antennas
JP4944255B2 (ja) * 2008-01-16 2012-05-30 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） デバイスを密閉するカバーの開放を検出する方法及びそのデバイス
US9137058B2 (en) 2008-07-17 2015-09-15 Nokia Technologies Oy Data packet processing for estimation of a direction towards a transmitter
US20180329018A9 (en) * 2008-07-25 2018-11-15 etherwhere Coporation System framework for mobile device location
CA2687675C (en) * 2008-12-08 2014-05-27 Electronics And Telecommunications Research Institute Apparatus and method for transmitting and receiving signal for handoff in broadcasting network
KR101479011B1 (ko) * 2008-12-17 2015-01-13 삼성전자주식회사 다중 대역 스케쥴링 방법 및 이를 이용한 방송 서비스 시스템
DE102009017426A1 (de) * 2009-03-03 2010-09-09 T-Mobile International Ag Verfahren und Mobilfunkendgerät zur Positionsbestimmung in Mobilfunknetzen mittels Richtungspeilung
KR100979623B1 (ko) * 2009-05-27 2010-09-01 서울대학교산학협력단 복수의 안테나를 포함한 무선 통신 장치 기반 위치 확인 시스템 및 방법
WO2011002188A2 (ko) * 2009-06-28 2011-01-06 엘지전자 주식회사 무선 통신 시스템에서 위치 기반 서비스를 위한 신호 전송 방법 및 이를 위한 장치
ES2363905B1 (es) * 2009-09-18 2012-06-22 Vodafone España, S.A.U. Diversidad de transmisión multiportadora en utran para hsdpa.
DE102009049978A1 (de) * 2009-10-20 2011-05-05 Siemens Aktiengesellschaft Verfahren und Vorrichtung zur relativen Lageerkennung von Funkortungsstationen
US9307431B2 (en) 2010-04-13 2016-04-05 Qualcomm Incorporated Reporting of channel properties in heterogeneous networks
US20110250919A1 (en) 2010-04-13 2011-10-13 Qualcomm Incorporated Cqi estimation in a wireless communication network
US9350475B2 (en) 2010-07-26 2016-05-24 Qualcomm Incorporated Physical layer signaling to user equipment in a wireless communication system
US9515773B2 (en) 2010-04-13 2016-12-06 Qualcomm Incorporated Channel state information reporting in a wireless communication network
US8588808B2 (en) 2010-05-24 2013-11-19 Nice-Systems Ltd. Method and system for estimation of mobile station velocity in a cellular system based on geographical data
US8200244B2 (en) 2010-05-24 2012-06-12 Nice Systems Ltd. Method and system for mobile station location
US8131312B2 (en) 2010-05-24 2012-03-06 Nice Systems Ltd. Method and system for construction of radio environment model
WO2011160100A1 (en) 2010-06-18 2011-12-22 Qualcomm Incorporated Channel quality reporting for different types of subframes
US9136953B2 (en) * 2010-08-03 2015-09-15 Qualcomm Incorporated Interference estimation for wireless communication
EP2482582B1 (en) 2011-01-26 2013-01-16 Alcatel Lucent Base station, method of operating a base station, terminal and method of operating a terminal
US8855000B2 (en) 2011-04-28 2014-10-07 Qualcomm Incorporated Interference estimation using data traffic power and reference signal power
EP2715869B1 (en) 2011-05-23 2018-04-18 Limited Liability Company "Radio Gigabit" Electronically beam steerable antenna device
US8391890B2 (en) * 2011-06-29 2013-03-05 Alcatel Lucent Method and apparatus for geo-locating mobile station
RU2585309C2 (ru) 2011-10-20 2016-05-27 Общество с ограниченной ответственностью "Радио Гигабит" Система и способ радиорелейной связи с электронной подстройкой луча
RU2530330C1 (ru) 2013-03-22 2014-10-10 Общество с ограниченной ответственностью "Радио Гигабит" Станция радиорелейной связи со сканирующей антенной
EP3175257A4 (en) * 2014-08-04 2018-06-20 MediaTek Inc. Main lobe and grating lobe identification for direction finding
US9872136B2 (en) * 2015-06-29 2018-01-16 Intel IP Corporation Method and apparatus for transmitter geo-location in mobile platforms
WO2017013304A1 (en) * 2015-07-23 2017-01-26 Nokia Technologies Oy Positioning method
EP3306337A1 (en) * 2016-10-10 2018-04-11 Fraunhofer Gesellschaft zur Förderung der Angewand User equipment localization in a mobile communication network
EP3321709A1 (en) * 2016-11-11 2018-05-16 Fraunhofer Gesellschaft zur Förderung der Angewand User equipment localization in a mobile communication network based on delays and path strengths
CN118900456A (zh) 2017-06-14 2024-11-05 弗劳恩霍夫应用研究促进协会 用于改善位置估计的装置、系统和方法
WO2020167073A1 (en) * 2019-02-14 2020-08-20 Samsung Electronics Co., Ltd. Position of user equipment
US11624801B2 (en) * 2021-03-31 2023-04-11 Red Point Positioning Corporation Method and system for determining the location of an object based on time difference of arrival (TDOA) and angle of arrival (AOA)
CN115413018A (zh) * 2021-05-26 2022-11-29 中兴通讯股份有限公司 信道状态信息处理方法、终端和计算机可读存储介质

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6026304A (en) * 1997-01-08 2000-02-15 U.S. Wireless Corporation Radio transmitter location finding for wireless communication network services and management
US6249680B1 (en) * 1997-01-08 2001-06-19 U.S. Wireless Corporation Radio transmitter location finding in CDMA wireless communication systems
US6064339A (en) * 1997-01-08 2000-05-16 Us Wireless Corporation Subspace signature matching for location ambiguity resolution in wireless communication systems
US6167274A (en) * 1997-06-03 2000-12-26 At&T Wireless Svcs. Inc. Method for locating a mobile station
US6671514B1 (en) * 1997-10-16 2003-12-30 Telefonaktiebolaget Lm Ericsson (Publ) System and method for location positioning a mobile station in a CDMA cellular system
AT407933B (de) * 1998-06-09 2001-07-25 Juha Dipl Ing Laurila Verfahren zur trennung und zur detektion von gleichkanal-signalen
US6501747B1 (en) * 1998-08-20 2002-12-31 Metawave Communications Corporation Manifold assisted channel estimation and demodulation for CDMA systems in fast fading environments
KR100378124B1 (ko) * 1998-12-10 2003-06-19 삼성전자주식회사 이동통신시스템에서단말기의위치추정장치및방법
US20050009528A1 (en) * 1999-10-21 2005-01-13 Mikio Iwamura Channel identifier assigning method and mobile communications system
US6351499B1 (en) * 1999-12-15 2002-02-26 Iospan Wireless, Inc. Method and wireless systems using multiple antennas and adaptive control for maximizing a communication parameter
US6870808B1 (en) * 2000-10-18 2005-03-22 Adaptix, Inc. Channel allocation in broadband orthogonal frequency-division multiple-access/space-division multiple-access networks
EP1338114B1 (en) * 2000-11-30 2009-03-11 ArrayComm LLC Training sequence for a radio communications system
US7254401B2 (en) * 2000-12-19 2007-08-07 Nokia Corporation Network-based method and system for determining a location of user equipment in CDMA networks
US6738020B1 (en) * 2001-07-31 2004-05-18 Arraycomm, Inc. Estimation of downlink transmission parameters in a radio communications system with an adaptive antenna array

Also Published As

Publication number Publication date
US20040072579A1 (en) 2004-04-15
WO2002054850A2 (en) 2002-07-18
WO2002054850A8 (en) 2003-10-30
EP1362492A2 (en) 2003-11-19
US7376428B2 (en) 2008-05-20
AU2002226447A1 (en) 2002-07-24
WO2002054850A3 (en) 2002-08-08
FI20010079A0 (fi) 2001-01-12

Similar Documents

Publication Publication Date Title
FI20010079A (fi) Paikannusmenetelmä ja radiojärjestelmä
DE60123892D1 (de) Funksystem
DE50214044D1 (de) Heterogenes mobilfunksystem
DE60218000D1 (de) Resonanzantenne
DE60138537D1 (de) Mehrfachgespeistes antennensystem
DE10192529T1 (de) Antennensystem
FI20010365A (fi) Menetelmä sijainnin määrityksessä, sijainninmääritysjärjestelmä ja elektroniikkalaite
DE60221613D1 (de) Tragbares Funkgerät
DE60132651D1 (de) Positionsbestimmungssystem
DE60128684D1 (de) Prozessorgest tzter drahtloser detektor
DE60144285D1 (de) Funknetzwerksystem
NO20034154D0 (no) Posisjoneringssystem
FI20012598A0 (fi) Menetelmä vastaanottimen toiminnan varmistamiseksi ja radiolaite
DE60019091D1 (de) Funkkommunikationssystem
DE50115257D1 (de) Funkgerät
FI20012095A0 (fi) Menetelmä ja järjestely koodaamiseksi
FI20002134A0 (fi) Koodisynkronointimenetelmä ja vastaanotin
DE60124644D1 (de) Tragbares funkgerät
DE50108211D1 (de) Funkgerät
FI981192A0 (fi) Paikannusmenetelmä ja radiojärjestelmä
FI980323A0 (fi) Foerfarande och anordning foer att maeta belaeggningsmaengden pao ett roerligt underlag
DE50010043D1 (de) Druckluftbehälter
FI20000273A (fi) Menetelmä suorittaa koodisynkronointi ja vastaanotin
FI20011603A0 (fi) Menetelmä palvelun toteuttamiseksi radiojärjestelmässä, radiojärjestelmän käyttäjälaite ja radiojärjestelmä
FI20001991A (fi) Menetelmä ja järjestelmä etätyöympäristöön