WO2002032157A2 - Commutation et transfert cellulaires commandes par une station mobile avec equilibrage de charge pour systemes sans fil - Google Patents

Commutation et transfert cellulaires commandes par une station mobile avec equilibrage de charge pour systemes sans fil Download PDF

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Publication number
WO2002032157A2
WO2002032157A2 PCT/CA2001/001407 CA0101407W WO0232157A2 WO 2002032157 A2 WO2002032157 A2 WO 2002032157A2 CA 0101407 W CA0101407 W CA 0101407W WO 0232157 A2 WO0232157 A2 WO 0232157A2
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WO
WIPO (PCT)
Prior art keywords
base stations
station
base station
information associated
base
Prior art date
Application number
PCT/CA2001/001407
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English (en)
Other versions
WO2002032157A3 (fr
Inventor
Mo-Han Fong
Wei Huang
Hang Zhang
Original Assignee
Nortel Networks Limited
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 Nortel Networks Limited filed Critical Nortel Networks Limited
Priority to AU2001295320A priority Critical patent/AU2001295320A1/en
Publication of WO2002032157A2 publication Critical patent/WO2002032157A2/fr
Publication of WO2002032157A3 publication Critical patent/WO2002032157A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/20—Selecting an access point

Definitions

  • the present invention is directed to communication via a wireless connection and, more particularly, to wireless communication capable of carrying voice and/or data signals at high data rates.
  • Recent wireless communication systems such as cellular systems that use code division multiple access (CDMA) technology, often employ a "soft handoff ' where, at any given time, a mobile station communicates with the network via more than one base transceiver station (BTS).
  • BTS base transceiver station
  • the soft handoff ensures that the mobile station communicates continuously with the network while the mobile station moves across cell regions covered by respective BTSs.
  • Soft handoff systems are prone to having the transmissions from one BTS interfere with those from another BTS. Also, when such systems are used to transfer data packets, complex scheduling of the routing of the packets is required which often delays the movement of the packets.
  • cell switching may be employed instead of a soft handoff. In cell switching, only the BTS having the best transmission channel quality is selected to transmit to the mobile station. The mobile station periodically measures the channel quality of each BTS in its active set, typically by measuring the carrier to interference ratio (C/I) of each BTS.
  • C/I carrier to interference ratio
  • the mobile station determines which BTS is transmitting at the highest channel quality and sends an indication of the desired BTS, namely the BTS transmitting at the highest channel quality, to each BTS in the active set.
  • a mobile station may be switched from one BTS to another BTS in its active set that is already heavily loaded.
  • the traffic load is unevenly distributed among the BTSs which results in traffic congestion and transmission delays that degrade the quality of service for some or all of the mobile stations that are served by the heavily loaded BTS.
  • the mobile stations be switched from one BTS to another in a manner that more evenly distributes the loading of the BTSs.
  • the network-side entity drives the switching from one BTS to another
  • signals representing the channel quality measurements are sent from the mobile stations to the network-side entity via the BTSs
  • signals informing the mobile station of the new BTS are sent from the network-side entity to the mobile stations via the BTSs.
  • the cell switching operation increases the amount of access network signaling and the amount of backhaul signaling. It is thus further desirable that the switching be driven by the mobile stations so that the amount of access network signaling and the amount of backhaul signaling needed to switch the mobile station from one BTS to' another be minimized.
  • the present invention provides for fast switching from one BTS to another that is
  • a remote station selects one of a plurality of base stations for communicating with the remote station.
  • Quality information associated with at least two of the plurality of base stations is determined at predefined intervals.
  • Loading information associated with the base stations is received at further predefined intervals.
  • a respective one of the base stations is selected as a function of the quality information and the loading information. Communication with the selected base station is initiated.
  • a remote station selects one of a plurality of base stations for communicating with the remote station.
  • Quality information associated with a respective one of the base stations that is currently communicating with the remote station and quality information associated with at least another of the base stations is determined at predefined intervals.
  • Loading information associated with the currently communicating base station and loading information associated with the at least another base station is received at further predefined intervals.
  • An associated value that is a function of the associated quality information and the associated loading information is determined for the currently communicating base station and for the at least another base station. Communication with the currently communicating base station is terminated and communication with the at least another base station is initiated when the associated value for the at least another base station exceeds the associated value for the currently communicating base station by a predetermined quantity.
  • the at least another base station may be selected from an active set of the remote station.
  • Figure 1 is a block diagram showing an example of a wireless communication arrangement in which a remote station communicates with one of a plurality of base transceiver stations under the control of a mobile control point.
  • Figure 2 is a flow chart illustrating a sequence of operations for selecting one of a plurality of base transceiver stations in accordance with the invention.
  • Figure 3 is a flow chart illustrating a sequence of operations for switching a remote station from one of a plurality of base transceiver stations to another in accordance with the
  • FIG. 1 illustrates an example of a cellular, wireless communication arrangement for providing voice and/or data services, such as packet data services, to a remote station.
  • a plurality of base transceiver stations (BTS) 110, 120, 130, ... are each assigned to respective geographic regions, known as cells.
  • a remote station 140 communicates with one of the BTS 110 of its active set, i.e. the set of nearby BTSs whose forward link transmissions could be received by the remote station.
  • the remote station may be a mobile station (MS), such as cellular telephone or other wireless
  • a mobile control point (MCP) 100 or other network-side control device directs each voice and/or data connection to a respective BTS via a cable connection.
  • the BTS provides a wireless link for the voice and/or data connection to the remote station.
  • the MCP may also send control information to the remote station and receive control information from the remote station via the BTS using, for example, inBand signaling.
  • a remote station When a remote station is located within the transmission range of more than one BTS, namely when the remote station is situated in a region where two or more cells overlap, it must determine the BTS with which it will communicate.
  • Figure 2 illustrates an example of a method, according to the invention, by which a remote station that is presently not communicating with a BTS selects one of the BTSs in its active set.
  • the remote station periodically measures the channel quality of
  • the transmission channel quality of each BTS is determined by the carrier to interference ratio (C/I) of the forward link transmission channel.
  • the C/I is defined as the ratio of the energy of the modulation carrier signal received from the BTS, integrated over time, to the energy of all other received signals that are on the same frequency band, integrated over time.
  • C/I carrier to interference ratio
  • other indications of the transmission channel quality may alternatively be used.
  • the C/I of the BTS may be based on a single value determined by integrating over the duration of one or more time slots that are each of a duration of, typically, 1.25 ms.
  • the C/I may be based on plural values that are each determined by integrating
  • the choice of method may be based on the conditions at the locations of the BTSs.
  • Each BTS also periodically determines its forward link loading condition L and delivers the loading condition information to the remote station, as step 202 shows.
  • the forward link loading condition L of the BTS is typically determined by the number of packets that are stored in its buffer and that are awaiting transmission, though other loading indicators may be used.
  • the forward link loading condition L may be determined with every time slot or at intervals of two or more time slots.
  • the remote station periodically determines a value K for each BTS that is a function of both the C/I and the forward link loading condition L.
  • the value K for each BTS is typically based on the relation:
  • i is the index of a respective BTS, and/ andf 2 are functions.
  • the remote station selects the BTS having the greatest K value, as step 206 shows, and notifies the selected BTS, such as by using a reverse link common channel or a dedicated signaling channel.
  • the remote station also sends the C/I associated with the BTS or sends a desired forward link data transmission rate that is determined from the C/I associated with the BTS .
  • the selected BTS then notified the MCP.
  • FIG. 3 shows an example of a method, according to the invention, by which a remote station that is presently communicating with a BTS determines whether to switch to another BTS in its active set.
  • the remote station periodically determines the channel quality of BTSs in its active set in the manner described above, as step 300 shows, and each BTS periodically determines its forward link loading condition L and delivers the loading condition information to the remote station in the above-described manner, as step 302 shows.
  • the remote station periodically determines a value K t for each BTS which is a function of both the C/I and the forward link loading condition L, also as described above.
  • K URGEST exceeds the K t value associated with the current BTS, K CURRENT , by a threshold value ⁇ , namely when
  • the remote station selects the BTS associated with £ ⁇ _ ?GJ _ S _ as step 308 shows.
  • the remote station notifies the selected BTS and sends the C/I associated with the BTS, or sends a desired forward link data transmission rate that is determined from the C/I associated with the BTS ? in the manner described above.
  • the selected BTS then notifies the
  • the remote station selects the current BTS, as shown at step 310, and need not send any signals to the BTS.
  • the remote stations does not switch from the current BTS to the BTS associated with
  • K- LARGEST unless K URGEST - K CURRENT exceeds ⁇ to prevent excessive switching from one BTS to another which could itself introduce transmission delays.
  • the remote station determines which BTS is to communicate with the remote station not only based on the channel quality of the BTS but also based on the loading condition of the BTS. As a result, the remote station is less likely to be switched to a heavily loaded cell, thereby reducing network congestion and signal delay and avoiding degradation of the quality of service.
  • the signals needed to cany out the selection of a BTS or the switching from one BTS to another are sent in only one direction, namely from the remote station to the BTS and from the BTS to the MCP. Because there is no additional inter-BTS signaling and no additional BTS-to-remote station signaling, there is no increase in backhaul signaling in the access network. The reduction in the amount of signaling also reduces the latency period between the time the remote station selects a BTS and the time BTS begins communication with the remote station.

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Une station distante sélectionne une pluralité de stations de base destinées à communiquer avec ladite station distante. Des informations de qualité associées à au moins deux stations de base sont déterminées à des intervalles prédéfinis. Des informations de charge associées aux stations de base sont reçues à d"autres intervalles prédéfinis. Une station de base respective est sélectionnée sous forme de fonction des informations de qualité et des informations de charge. La communication avec la station de base sélectionnée est initiée.
PCT/CA2001/001407 2000-10-13 2001-10-04 Commutation et transfert cellulaires commandes par une station mobile avec equilibrage de charge pour systemes sans fil WO2002032157A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001295320A AU2001295320A1 (en) 2000-10-13 2001-10-04 Mobile station driven cell switching and handoff with load balancing for wireless systems

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US68732800A 2000-10-13 2000-10-13
US09/687,328 2000-10-13

Publications (2)

Publication Number Publication Date
WO2002032157A2 true WO2002032157A2 (fr) 2002-04-18
WO2002032157A3 WO2002032157A3 (fr) 2002-08-22

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AU (1) AU2001295320A1 (fr)
WO (1) WO2002032157A2 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1319333C (zh) * 2002-06-26 2007-05-30 诺基亚公司 负载均衡方法、系统、负载控制设备和接入点、用户终端
CN100334853C (zh) * 2004-07-01 2007-08-29 中兴通讯股份有限公司 一种利用无线网络信息实现无线局域网负载均衡的方法
CN100369428C (zh) * 2004-06-28 2008-02-13 中兴通讯股份有限公司 在无线局域网内建立联接和再次联接的方法
EP1954077A1 (fr) * 2007-02-02 2008-08-06 Research In Motion Limited Sélection de cellules basée sur la largeur de bande dans un réseau cellulaire
GB2474503A (en) * 2009-10-19 2011-04-20 Ubiquisys Ltd Controlling mobility in cellular networks using home cell hysteresis and neighbour cell offsets and taking neighbour cell loading into account
US8081978B2 (en) 2007-02-02 2011-12-20 Reseach In Motion Limited Bandwidth-based cell selection in a cellular network
WO2014182489A3 (fr) * 2013-05-10 2015-03-05 Qualcomm Incorporated Procédé et appareil d'estimation de rendement de liaison réalisable sur la base d'informations d'assistance
US9301161B2 (en) 2012-07-27 2016-03-29 Qualcomm Incorporated Method and apparatus for available bandwidth estimation by a user equipment in idle and/or connected mode

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4765753A (en) * 1986-03-08 1988-08-23 U.S. Philips Corporation Method and apparatus for handing-over a radio connection from one radio cell to another radio cell of a digital radio transmission system
EP0530165A2 (fr) * 1991-08-23 1993-03-03 Telefonaktiebolaget L M Ericsson Transfert commandé par la station mobile
WO1999014972A2 (fr) * 1997-09-17 1999-03-25 Nokia Mobile Phones Limited Procede avance d'execution de transfert
WO1999051052A1 (fr) * 1998-04-01 1999-10-07 Telefonaktiebolaget Lm Ericsson (Publ) Selection de cellules dans des systemes radio mobiles
WO1999059368A1 (fr) * 1998-05-14 1999-11-18 Simoco International Limited Commande de transfert dans un systeme de communication radio

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4765753A (en) * 1986-03-08 1988-08-23 U.S. Philips Corporation Method and apparatus for handing-over a radio connection from one radio cell to another radio cell of a digital radio transmission system
EP0530165A2 (fr) * 1991-08-23 1993-03-03 Telefonaktiebolaget L M Ericsson Transfert commandé par la station mobile
WO1999014972A2 (fr) * 1997-09-17 1999-03-25 Nokia Mobile Phones Limited Procede avance d'execution de transfert
WO1999051052A1 (fr) * 1998-04-01 1999-10-07 Telefonaktiebolaget Lm Ericsson (Publ) Selection de cellules dans des systemes radio mobiles
WO1999059368A1 (fr) * 1998-05-14 1999-11-18 Simoco International Limited Commande de transfert dans un systeme de communication radio

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1319333C (zh) * 2002-06-26 2007-05-30 诺基亚公司 负载均衡方法、系统、负载控制设备和接入点、用户终端
CN100369428C (zh) * 2004-06-28 2008-02-13 中兴通讯股份有限公司 在无线局域网内建立联接和再次联接的方法
CN100334853C (zh) * 2004-07-01 2007-08-29 中兴通讯股份有限公司 一种利用无线网络信息实现无线局域网负载均衡的方法
EP1954077A1 (fr) * 2007-02-02 2008-08-06 Research In Motion Limited Sélection de cellules basée sur la largeur de bande dans un réseau cellulaire
AU2008200211B2 (en) * 2007-02-02 2010-09-30 Blackberry Limited Bandwidth-based cell selection in a cellular network
US8081978B2 (en) 2007-02-02 2011-12-20 Reseach In Motion Limited Bandwidth-based cell selection in a cellular network
GB2474503A (en) * 2009-10-19 2011-04-20 Ubiquisys Ltd Controlling mobility in cellular networks using home cell hysteresis and neighbour cell offsets and taking neighbour cell loading into account
GB2474503B (en) * 2009-10-19 2014-05-21 Ubiquisys Ltd Controlling mobility in cellular networks
US9374752B2 (en) 2009-10-19 2016-06-21 Ubiquisys Limited Controlling mobility in cellular networks
US9301161B2 (en) 2012-07-27 2016-03-29 Qualcomm Incorporated Method and apparatus for available bandwidth estimation by a user equipment in idle and/or connected mode
WO2014182489A3 (fr) * 2013-05-10 2015-03-05 Qualcomm Incorporated Procédé et appareil d'estimation de rendement de liaison réalisable sur la base d'informations d'assistance
US9538439B2 (en) 2013-05-10 2017-01-03 Qualcomm Incorporated Method and apparatus for estimating an achievable link throughput based on assistance information

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WO2002032157A3 (fr) 2002-08-22
AU2001295320A1 (en) 2002-04-22

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