US20120214495A1 - Apparatus and method for controlling handover to prevent femtocell interference - Google Patents

Apparatus and method for controlling handover to prevent femtocell interference Download PDF

Info

Publication number
US20120214495A1
US20120214495A1 US13/399,216 US201213399216A US2012214495A1 US 20120214495 A1 US20120214495 A1 US 20120214495A1 US 201213399216 A US201213399216 A US 201213399216A US 2012214495 A1 US2012214495 A1 US 2012214495A1
Authority
US
United States
Prior art keywords
frequency
handover
inter
base station
cell
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.)
Abandoned
Application number
US13/399,216
Other languages
English (en)
Inventor
Byoung-jin Choi
Tae-Won Ban
Chang-Yong Ahn
Sung-Sang You
Kyeong-Soo Lee
Hee-Jun Lee
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.)
KT Corp
Original Assignee
KT 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 KT Corp filed Critical KT Corp
Assigned to KT CORPORATION reassignment KT CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AHN, CHANG-YONG, BAN, Tae-Won, CHOI, BYOUNG-JIN, LEE, HEE-JUN, LEE, KYEONG-SOO, YOU, Sung-Sang
Publication of US20120214495A1 publication Critical patent/US20120214495A1/en
Priority to US14/329,114 priority Critical patent/US9241290B2/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H04W36/0072—Transmission or use of information for re-establishing the radio link of resource information of target access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/06—Reselecting a communication resource in the serving access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B15/00—Suppression or limitation of noise or interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/04—Reselecting a cell layer in multi-layered cells
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04—Large scale networks; Deep hierarchical networks
    • H04W84/042—Public Land Mobile systems, e.g. cellular systems
    • H04W84/045—Public Land Mobile systems, e.g. cellular systems using private Base Stations, e.g. femto Base Stations, home Node B

Definitions

  • the present invention relates to communication networks and, in particular, to controlling handover.
  • a femtocell is a small cellular base station that provides a mobile communication service in a comparatively narrow area.
  • the femtocell has various advantages of expanding indoor service coverage, improving service quality, and effectively providing various wired and wireless integrated services.
  • the femtocell has low installation and maintenance fees. Further, the femtocell can be installed in any location where an Internet channel is available.
  • One of the main purposes of introducing a femtocell is to distribute network load in a macrocell and to increase service capacity of the macrocell.
  • a plurality of femtocells may be installed within a service area of a macrocell in order to overcome a shortage in the service capacity of a macrocell. Since multiple femtocells are installed within a single macrocell, the femtocells, however, may cause a frequency interference problem, known as femtocell interference.
  • femtocells may be allocated with the same identification codes.
  • Each base station is allocated an identification code in order for the base station to be distinguished from other base stations.
  • For efficient system management only a limited number of identification codes is available. Most of the available identification codes are allocated to macrocell base stations first, and only the few remaining identification codes may be allocated to femtocell base stations. Due to a shortage of identification codes, the same identification codes may be reused for multiple femtocell base stations installed in a service area of a macrocell. Such duplication of identification codes may cause a failure of the inter-cell handover from a macrocell base station to a femtocell base station.
  • a target femtocell base station may not be distinguishable from other femtocell base stations.
  • the handover procedure may fail.
  • Such a failure in handover may also cause serious frequency interference problems.
  • Such frequency interference problems may degrade the service quality of the overall communication network and deteriorate the load distribution effect of femtocell.
  • Embodiments of the present invention overcome the above disadvantages and other disadvantages not described above. Also, the present invention is not required to overcome the disadvantages described above, and an embodiment of the present invention may not overcome any of the problems described above.
  • handover may be controlled in consideration of femtocell interference.
  • inter-frequency handover may be performed when inter-cell handover from a macrocell to a femtocell is requested.
  • a method may be provided for controlling handover in a communication network where a first cell is overlapped with a plurality of second cells.
  • the method may include receiving a request of inter-cell handover from a first cell base station of the first cell to a second cell base station of one of the second cells, and performing an inter-frequency handover in response to the request of the inter-cell handover.
  • User equipment may make the request of inter-cell handover when the user equipment in a traffic state enters into the one of the second cells.
  • the receiving a request of inter-cell handover may include determining whether the second cells are femtocells.
  • the inter-frequency handover is performed if the second cells are femtocells.
  • the method may further include performing the inter-cell handover from the first cell base station to the second cell base station when the second cells are macrocells.
  • the receiving a request of inter-cell handover may include determining whether a first frequency used by the first cell base station is equivalent to a second frequency assigned to the second cell base station, and performing the inter-frequency handover.
  • the method may further include performing the inter-cell handover from the first cell base station to the second cell base station when the first frequency is different from the second frequency.
  • the performing the inter-frequency handover in response to the request of the inter-cell handover may include selecting an unshared frequency, and performing the inter-frequency handover to the selected unshared frequency.
  • the unshared frequency may be a frequency unassigned to the one of the second cells.
  • a frequency having load less than a given load level and quality higher than a given quality level may be selected from frequencies assigned to the first cell and unassigned to the second cells.
  • user equipment may be coupled to the first cell base station using the selected unshared frequency.
  • a method may be provided for controlling handover in a communication network where a macrocell is overlapped with a plurality of femtocells.
  • the method may include transmitting a measurement control message to user equipment when the user equipment in a traffic state enters from the macrocell to one of the femtocells, receiving a measurement report message from the user equipment, determining whether the measurement report message includes a request of inter-cell handover from a macrocell base station of the macrocell to a femtocell base station of the one of the femtocells, selecting an unshared frequency from unshared frequencies assigned to a macrocell base station of the macrocell and unassigned to a femtocell base station of the one of the femtocells when the measurement report message includes the request of inter-cell handover from the macrocell to the one of the femtocells, and performing inter-frequency handover based on the selected unshared frequency in response to the request
  • the method may further include performing the inter-cell handover from the macrocell to another macrocell when the measurement report message includes a request of inter-cell handover from the macrocell to another macrocell,
  • the method may further include determining whether a first frequency used by the macrocell base station is equivalent to a second frequency assigned to the femtocell base station, performing an inter-cell handover from the macrocell base station to the femtocell base station when the first frequency is different from the second frequency, and performing the inter-frequency handover using the unshared frequency when the first frequency is equivalent to the second frequency.
  • an apparatus may be provided for controlling handover in a communication network where a first cell is overlapped with a plurality of second cells.
  • the apparatus may include an event receiving module, a handover determining module, and an inter-frequency processing module.
  • the event receiving module may be configured to receive a control message from user equipment
  • the handover determining module may be configured to analyze the received control message and determine whether the control message includes a request of inter-cell handover from a first cell base station of the first cell to a second cell base station of one of the second cells.
  • the inter-frequency processing module may be configured to perform inter-frequency handover using an unshared frequency when the handover determining module determines that the control message includes the request of inter-cell handover.
  • the event receiving module may receive the control message when the user equipment in a traffic state enters the one of the second cells.
  • the handover determining module may determine whether or not the second cell base station is a femtocell base station.
  • the inter-frequency processing module may perform the inter-frequency handover when the second cell base station is the femtocell base station.
  • the apparatus may further include an inter-cell handover processing module.
  • the inter-cell handover processing module may be configured to perform an inter-cell handover when the handover determining module determines that the second base station is a macrocell base station,
  • the handover determining module may determine whether or not a first frequency used by the first cell base station is equivalent to a second frequency assigned to the second cell base station.
  • the inter-frequency processing module may perform the inter-frequency handover when the first frequency is equivalent to the second frequency.
  • the apparatus may further include an inter-cell handover processing module.
  • the inter-cell handover processing module may be configured to perform an inter-cell handover when the first frequency is different from the second frequency.
  • the handover determining module may include a frequency selector.
  • the frequency selector may be configured to select the unshared frequency from frequencies assigned to the first cell base station and un assigned to the second cell base station. A frequency having load less than a given load level and quality higher than a given quality level may be selected from the frequencies, as the unshared frequency.
  • the user equipment may be coupled to the first cell base station using the unshared frequency.
  • FIG. 1 illustrates a mobile communication system in accordance with an exemplary embodiment of the present invention
  • FIG. 2 illustrates frequency assignment in macrocell and femtocells
  • FIG. 3 illustrates inter-frequency handover performed to prevent femtocell interference in accordance with an exemplary embodiment of the present invention
  • FIG. 4 illustrates a method for controlling handover to prevent femtocell interference in accordance with an embodiment of the present invention
  • FIG. 5 illustrates a method for controlling handover to prevent femtocell interference in accordance with another exemplary embodiment of the present invention.
  • FIG. 6 illustrates an apparatus for controlling handover to prevent femtocell interference in accordance with an embodiment of the present invention.
  • FIG. 1 illustrates a mobile communication system in accordance with an exemplary embodiment of the present invention.
  • mobile communication system 100 may include a macrocell base station 111 , femtocell base stations 211 , 212 , and 213 , core network 300 , base station controller 120 , and femtocell gateway 250 .
  • macrocell 110 may be overlapped with multiple femtocells 210 , 220 , and 230 .
  • Macrocell 110 may be a typical radio access cell of a wireless communication system.
  • Macrocell 110 may include microcell base station 110 .
  • Macrocell 110 may provide a mobile communication service to user equipment 900 through microcell base station 110 .
  • Femtocells 210 , 220 , and 230 may be radio access cells installed for maintaining a proper quality level of a mobile communication service in a shadow area of a macrocell and for expanding service quantity of a macrocell. As shown in FIG. 1 , femtocells 210 , 220 , and 230 may be installed inside macrocell 110 . Femtocells 210 , 220 , and 230 may include femtocell base stations 211 , 212 , and 213 , respectively. Femtocell base stations 211 , 212 , and 213 may be coupled to Internet protocol (IP) network 500 and femtocell gateway 250 .
  • IP Internet protocol
  • user equipment 900 may perform an inter-cell handover procedure from macrocell base station 111 to corresponding one of femtocell base stations 211 , 212 , and 213 .
  • Femtocells 210 , 220 , and 230 may be coupled to core network 300 through IP network 500 and femtocell gateway 250 .
  • Core network 300 may be a mobile communication network for providing a data service and a voice service.
  • Core network 300 may be coupled to macrocell 110 through serving GPRS support node (SGSN) 400 .
  • Core network 300 may be coupled to femtocells 210 , 220 , and 230 through femtocell gateway 250 and IP network 500 .
  • core network 300 may provide a data service and a voice service to user equipment 900 in macrocell 110 or femtocells 210 , 220 , and 230 .
  • Macrocell base station 111 may be an access point for macrocell 110 .
  • Macrocell base station 111 may be coupled to base station controller 120 and may manage radio resources in response to the control of base station controller 120 .
  • macrocell base station 111 may be a base station transceiver subsystem (BTS) or a Node B.
  • BTS base station transceiver subsystem
  • Base station controller 120 may allocate and release a radio channel, control transmission of user equipment 900 and macrocell base station 111 , determine inter-cell handover and/or inter-frequency handover, manage radio resources, and manage and maintain macrocell base station 111 .
  • Femtocell gateway 250 may couple IP network 500 to core network 300 . Accordingly, femtocell gateway 250 may enable user equipment 900 to access femtocell base stations 211 , 212 , and 213 to communicate with other user equipment. Femtocell gateway 250 may receive data such as mobile contents through core network 300 to transmit the received data to user equipment 900 accessing one of femtocell base stations 211 , 212 , and 213 . Femtocell gateway 250 may perform protocol conversion between core network 300 and IP network 500 .
  • Femtocell base stations 211 , 212 , and 213 may be installed at a shadow area or an area in macrocell 110 , where a radio signal of macrocell 110 is weak.
  • femtocell base stations 211 , 212 , and 213 may be installed within a service area of macrocell 110 to increase service capacity of macrocell 110 and to distribute network load in macrocell 110 .
  • Femtocell base stations 211 , 212 , and 213 may be allocated with identification codes. As described above, such identification codes are reused with other femtocell base stations or macrocell base stations because the number of available identification codes is limited for efficiently managing radio resources in an associated communication network.
  • femtocell base stations 211 , 212 , and 213 may be allocated the same identification code PSC# 0 .
  • Femtocell base station 211 When user equipment 900 in macrocell service area 110 transitions to femtocell service area 210 , an inter-cell handover procedure from macrocell base station 111 to femtocell base station 211 may be initiated.
  • Femtocell base station 211 has an identification code PSC# 0 which is the same as the identification code used by the other femtocell base stations 212 and 213 . Since a network cannot accurately identify femtocell base station 211 where user equipment 900 transitions to femtocell service area 210 , a handover procedure cannot be normally performed. Accordingly, user equipment 900 may fail in handover from macrocell 110 to femtocell 210 due to duplication of femtocell identification codes.
  • Such a handover failure may cause a frequency interference problem between a macrocell and a femtocell using a same frequency, which is known as femtocell interference.
  • the frequency interference problem may degrade service quality and overall system performance. Furthermore, the frequency interference problem may decrease service capacities of both the macrocell and femtocells.
  • a handover procedure may be controlled in consideration of femtocell interference. For example, when user equipment 900 attempts to perform handover from macrocell 110 to one of femtocells 210 , 220 , and 230 , inter-frequency handover may be performed instead of performing inter-cell handover. This manner of controlling a handover procedure may prevent the frequency interference problem occurring in an associated communication network.
  • radio resources including frequencies are limited in a communication network
  • some of the frequencies used are carefully assigned for communication in macrocells and femtocells.
  • such a frequency assignment will be briefly described with reference to FIG. 2 .
  • FIG. 2 illustrates frequency assignment in macrocell and femtocells.
  • frequencies f1 to fN may be available for assignment to macrocell and femtocells.
  • frequencies f1 to fN frequencies f1 to fC may be commonly assigned to femtocells and macrocells. That is, frequencies f1 to fC are termed herein as “shared frequencies.”
  • Frequencies f(C+1) to fN may be dedicated for assignment to macrocells, termed herein as “unshared frequencies.” That is, frequencies f(C+1) to fN may be unshared frequencies within a macrocell.
  • radio resources such as frequencies for transmission are limited in a communication network. In order to efficiently utilize such limited frequencies, a comparative larger number of frequencies are assigned to macrocells, as compared to the number of frequencies assigned to femtocells, and femtocells may share some of frequencies assigned to the macrocells.
  • frequency interference problems may be arisen when the macrocell and the femtocell use the shared frequencies f1 to fC.
  • an inter-frequency handover is performed when, and subsequently in place of, an inter-cell handover request between a macrocell and a femtocell in accordance with an exemplary embodiment of the present invention.
  • inter-frequency handover performed to prevent femtocell interference in accordance with an exemplary embodiment of the present invention will be described with reference to FIG. 3 .
  • FIG. 3 illustrates inter-frequency handover performed to prevent femtocell interference in accordance with an exemplary embodiment of the present invention.
  • a shared frequency fl may be assigned to both of macrocell 310 and femtocell 311 .
  • Unshared frequencies 12 to f4 may be dedicatedly assigned to macrocells 320 to 340 .
  • User equipment 300 may communicate with other user equipment or receive a data service from an associated server using frequency f1 when user equipment 300 stays at an area A in a service area of macrocell 310 outside of the area of femtocell 311 .
  • user equipment 300 may attempt to perform handover from macrocell 310 to femtocell 311 .
  • an inter-frequency handover is performed instead of the inter-cell handover in accordance with an exemplary embodiment of the present invention.
  • the femtocell base station may transmit a handover request to a base station controller of macrocell 310 .
  • the base station controller may select one frequency from unshared frequencies f2 to f4 based on a load and a quality thereof.
  • the base station controller may select an unshared frequency having less load and excellent quality from unshared frequencies 12 to f4.
  • FIG. 3 illustrates unshared frequency f3 is selected, but the present invention is not limited thereto.
  • the base station controller may perform inter-frequency handover from shared frequency fl to unshared frequency f3, in accordance with an exemplary embodiment of the present invention, Macrocells 310 , 320 , 330 , and 340 are illustrated as being assigned with only one frequency in FIG. 3 .
  • each macrocell may be assigned multiple frequencies.
  • a macrocell base station of macrocell 310 may be assigned multiple frequencies f1 and f3.
  • a service base station and a target base station may be same in inter-frequency handover.
  • inter-cell handover from macrocell 310 to femtocell 311 is not performed although user equipment 300 enters to the service area B of femtocell 311 , in accordance with an exemplary embodiment of the present invention.
  • inter-frequency handover from shared frequency f1 to unshared frequency f3 may be performed. That is, a frequency assigned to macrocell may become different from a frequency assigned to femtocell as a result of the inter-frequency handover. Accordingly, a frequency interference problem may not arise although inter-cell handover from macrocell to femtocell is failed.
  • a channel may be established between user equipment 900 and macrocell base station 111 at step S 401 .
  • User equipment 900 may be located in a service area of macrocell 110 .
  • user equipment 900 may be in a traffic state at step S 402 .
  • traffic state user equipment 900 may communicate with other user equipment or receive and transmit data through the channel established to femtocell base station 111 .
  • user equipment 900 may measure a peripheral wireless environment, create a measurement report message, and transmit the measurement report message to the macrocell base station 111 at step S 405 .
  • Macrocell base station 111 may receive the measurement report message at step S 406 .
  • Macrocell base station 111 may analyze the received measurement report message whether a handover request event is included in the measurement report message at step S 407 . When the measurement report message does not include the handover request event (No-step S 407 ), the method returns to step S 402 .
  • the measurement report message includes the handover request event (Yes-step S 407 )
  • determination may be made as to whether the handover request event is an inter-cell handover request from macrocell 110 to femtocell 210 at step S 408 .
  • the handover request event is the inter-cell handover request from macrocell 110 to another macrocell (No-step S 408 )
  • an inter-cell handover from macrocell 110 to other macrocell may be performed at step S 409 .
  • the handover request event is the inter-cell handover request from macrocell 110 to femtocell 210 (Yes-step S 408 )
  • determination may be made as to whether or not macrocell 110 and femtocell 210 use a same frequency at step S 410 .
  • macrocell 110 and femtocell 210 use different frequencies (No-step S 410 )
  • an inter-cell handover from macrocell 110 to femtocell 210 may be performed at step S 411 .
  • macrocell base station 111 may select an unshared frequency at step S 412 . That is, macrocell base station 111 may initiate an inter-frequency handover instead of inter-cell handover in accordance with an exemplary embodiment of the present invention. Macrocell base station 111 may select an unshared frequency from a group of available unshared frequencies. Macrocell base station 111 may select one having comparative less load and higher quality the group of available unshared frequencies.
  • macrocell base station 111 may perform inter-frequency handover with the selected unshared frequency at step S 413 .
  • macrocell base station 111 may be changed to a macrocell base station assigned with the selected unshared frequency, and a frequency of user equipment 900 may be changed to the selected unshared frequency.
  • the inter-frequency handover from a shared frequency to an unshared frequency may be performed although an inter-cell handover from macrocell 110 to femtocell 210 is requested, in accordance with an exemplary embodiment of the present invention.
  • user equipment 900 may use a different frequency from that of femtocell 210 . Accordingly, frequency interference problems such as femtocell interference may be prevented.
  • Such a method may be further more effective when femtocell base stations cannot be identified in an associated communication network due to duplication of identification codes and when the signal strength of a macrocell base station is stronger than that of a femtocell base station.
  • FIG. 5 illustrates a method for controlling handover to prevent femtocell interference in accordance with another exemplary embodiment of the present invention.
  • the method for controlling handover to prevent femtocell interference will be described as controlling handover in a wideband code division multiple access (WCDMA) system.
  • WCDMA wideband code division multiple access
  • the present invention is not limited thereto.
  • the method for controlling handover to prevent femtocell interference may be applied to a typical mobile communication system including a code division multiple access (CDMA) system, a global system for mobile communications (GSM) system, and an orthogonal frequency-division multiplexing (OFDM) system.
  • CDMA code division multiple access
  • GSM global system for mobile communications
  • OFDM orthogonal frequency-division multiplexing
  • a radio resource control (RRC) connection may be established between user equipment 710 and base station controller 730 and a call session may be set through the RRC connection at step S 502 .
  • RRC radio resource control
  • the idle state of user equipment 710 may transit to a traffic state.
  • User equipment 710 may form a channel through a shared frequency f1 to macrocell base station, for example, serving base station 720 , and communicate with other entity on an associated communication network.
  • the shared frequency f1 may be a frequency commonly used with femtocells included in the neighbor list.
  • User equipment 710 may enter a femtocell service area of femtocell 740 while communication with other entity at step S 503 .
  • femtocell 740 may be a target base station using the shared frequency f1.
  • base station controller 730 may detect the entering of the femtocell service area and transmit a measurement control message to user equipment 710 through serving base station 720 at step S 504 .
  • the measurement control message may invoke user equipment 710 to measure peripheral radio environment.
  • the measurement control message may include a neighbor list. For example, identification codes of femtocell base stations may be included in the neighbor list.
  • User equipment 710 may receive the measurement control message from base station controller 730 through serving base station 720 .
  • Serving base station 720 may be a macrocell base station using a shared frequency f1.
  • user equipment 710 may measure radio signal strengths of neighboring base stations, create a measurement report message based on the measurement result, and transmit the measurement repot message to base station controller 730 through serving base station 720 at step S 505 .
  • the measurement report message may include information on a handover request event. For example, user equipment 710 may measure the radio signal strengths of base stations included in the neighbor list and compare the measured radio signal strengths to each other.
  • user equipment 710 may compare the measured radio signal strength with a given threshold, Based on the comparison result, user equipment 710 may select one base station satisfying a given condition and generate a handover request event based on the selected base station.
  • Handover request events may be invoked with various methods.
  • Base station controller 730 may receive the measurement report message from user equipment 710 through serving base station 720 and determine whether the measurement report message includes a handover request event at step S 506 . Base station controller 730 may also determine whether the handover request event is a request for handover from a macrocell to a femtocell. When the handover request event is a request for handover from a macrocell to another macrocell, an inter-cell handover from a macrocell to another macrocell may be performed.
  • an inter-frequency handover may be initiated instead of inter-cell handover from a macrocell to a femtocell, in accordance with another exemplary embodiment of the present invention.
  • base station controller 730 may select an unshared frequency fx at step 8507 .
  • Base station controller 730 may select an unshared frequency having comparative less load and better quality from available unshared frequencies.
  • a frequency of serving base station Before selection of an unshared frequency fx, a frequency of serving base station may be compared with a frequency of a target base station. When the frequency of the serving base station is different from that of the base station, an inter-cell handover from a macrocell to a femtocell may be performed.
  • the present invention is not limited thereto.
  • base station controller 730 may perform the inter-frequency handover to the selected frequency fx.
  • a radio link may be established to target base station 740 using the selected frequency fx at step 5508 . Since femtocells are not allocated unshared frequencies, a femtocell base station cannot be selected as a target base station.
  • a serving base station may be selected again as a target base station because a base station may be assigned with multiple unshared frequencies. Accordingly, serving base station 720 may be selected as target base station 740 when serving base station 720 is also assigned with unshared frequency fx. The present invention, however, is not limited thereto.
  • Another femtocell base station assigned with the selected unshared frequency fx may be selected as target base station 740 .
  • an uplink and a downlink may be synchronized with the selected frequency fx of target base station 740 at step S 509 .
  • Base station controller 730 may request user equipment 710 to reconfigure a physical channel through serving base station 720 at step S 510 .
  • user equipment 710 may reconfigure a physical channel by performing a frequency change procedure at step S 511 .
  • user equipment 710 may release a physical channel established using the shared frequency f1 and establish a physical channel using the selected frequency fx.
  • User equipment 710 may transmit a physical channel reconfigure complete message to base station controller 730 through target base station 740 at step S 512 .
  • the inter-frequency handover may be completed.
  • an unshared frequency may be selected and an inter-frequency handover to the selected unshared frequency may be performed instead of performing the inter-cell handover, in accordance with an exemplary embodiment of the present invention. Accordingly, a femtocell interference problem and/or a handover failure problem may be prevented in accordance with an exemplary embodiment of the present invention.
  • the method for controlling handover to prevent femtocell interference may further include a compressed mode (CM) procedure at step S 513 .
  • CM compressed mode
  • Such a CM procedure may be performed after selecting an unshared frequency fx. For example, a cell quality of a base station assigned with the selected unshared frequency fx may be analyzed with a compressed mode. When the cell quality is higher than a given quality level, an associated handover may be permitted.
  • FIG. 6 illustrates an apparatus for controlling handover to prevent femtocell interference in accordance with an embodiment of the present invention.
  • apparatus 600 for controlling handover to prevent femtocell interference may include event receiving module 610 , handover determining module 620 , and handover processing module 630 .
  • Apparatus 600 may be a base station controller of an associated mobile communication system, but the present invention is not limited thereto.
  • apparatus 600 may be an independent server coupled to the base station controller or be integrally implemented with the base station controller.
  • Event receiving module 610 may receive an event message from user equipment through a serving base station.
  • Event receiving module 610 may include measurement control (MC) message transmitter 612 and measurement report (MP) message receiver 614 .
  • MC message transmitter 612 may transmit a measurement control message to user equipment through a serving base station.
  • Apparatus 600 may control user equipment to measure peripheral radio environment through the measurement control message.
  • MR message receiver 614 may receive a measurement report message from the user equipment through the serving base station.
  • the user equipment may measure peripheral radio environment, create the measurement report message based on the measurement result, and transmit the measurement repot message to MR message receiver 614 through the serving base station.
  • the measurement report message may include information on the result of measuring peripheral radio environment and an event generated based on the measurement result.
  • the event may be a handover request event.
  • Handover determining module 620 may determine whether inter-cell handover is requested based on the measurement report message. For example, handover determining module 620 may analyze the received measurement report message, determine whether the received measurement report message includes a handover request event, and determine whether the handover request event is a request of inter-cell handover from a macrocell to a femtocell. Handover determining module 620 may perform the determination operation for user equipment in a traffic state.
  • Handover processing module 630 may process a handover procedure according to the determination result of handover determining module 620 .
  • Handover processing module 630 may include event determiner 631 , frequency selector 633 , inter-frequency handover processor 635 , and inter-cell handover processor 637 .
  • Event determiner 631 may determine whether the handover request event is an inter-cell handover from a macrocell to a femtocell. When event determiner 631 determines that the handover request event is an inter-cell handover from a macrocell to a femtocell, event determiner 631 may control frequency selector 633 and inter-frequency handover processor 635 to perform an inter-frequency handover. When event determiner 631 determines that the handover request event is an inter-cell handover from a macrocell to a macrocell, event determiner 631 may control inter-cell handover processor 637 to perform the inter-cell handover from a macrocell to another macrocell.
  • event determiner 631 may determine whether a same shared frequency is used by a serving macrocell base station and a target femtocell base station. When event determiner 631 determines that different shared frequencies are used by both of the serving macrocell base station and the target femtocell base station, event determiner 631 may control inter-cell handover processor 637 to perform an inter-cell handover from a macrocell to a femtocell,
  • Frequency selector 633 may select an unshared frequency in response to the control of event determiner 631 .
  • the unshared frequency may be a frequency not used by a femtocell base station and only used by a macrocell base station. When multiple unshared frequencies are available, frequency selector 633 may select one having comparative less load and better quality from multiple unshared frequencies. Furthermore, frequency selector 633 may select an unshared frequency having a load less than a given load level and a quality higher than a given quality level from multiple unshared frequency.
  • Inter-frequency handover processor 635 may perform inter-frequency handover based on the selected unshared frequency in response to the control of event determiner 631 .
  • inter-frequency handover processor 635 may receive the selected unshared frequency from frequency selector 633 .
  • Inter-frequency handover processor 635 may perform handover to a target macrocell base station assigned with the selected unshared frequency.
  • the target macrocell base station may be a serving macrocell base station when the serving macrocell base station is assigned with multiple frequencies including the selected unshared frequency.
  • Inter-cell handover processor 637 may perform inter-cell handover from a macrocell to a macrocell in response to the control of event determiner 631 . For example, when event determiner 631 determines that the handover request event is inter-cell handover from a macrocell to another macrocell, inter-cell handover processor 637 may perform inter-cell handover. For another example, when event determiner 631 determines that a current frequency used by a serving macrocell base station is different from a frequency used by a target femtocell base station, inter-cell handover processor 637 may perform inter-cell handover from the serving macrocell base station to the target femtocell base station.
  • apparatus 600 for controlling handover to prevent femtocell interference may perform the inter-frequency handover to an unshared frequency instead of the inter-cell handover from a macrocell to a femtocell when user equipment in a traffic state attempts to handover from a serving macrocell base station to a target femtocell base station, in accordance with an exemplary embodiment of the present invention. Accordingly, the femtocell interference problem and/or the handover failure problem may be prevented in accordance with an exemplary embodiment of the present invention.
  • a femtocell or a femtocell base station may be referred to a microcell, a microcell base station, a picocell, a picocell base station, an ubicell, and an ubicell base station. Accordingly, such base station may be understood as any access point that communicates with user equipment through short-range communication and provides an Internet service to user equipments.
  • exemplary is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion.
  • the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations, That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances.
  • the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.
  • a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer.
  • an application running on a controller and the controller can be a component.
  • One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers.
  • the present invention can be embodied in the form of methods and apparatuses for practicing those methods.
  • the present invention can also be embodied in the form of program code embodied in tangible media, such as magnetic recording media, optical recording media, solid state memory, floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention.
  • the present invention can also be embodied in the form of program code, for example, whether stored in a storage medium, loaded into and/or executed by a machine, or transmitted over some transmission medium or carrier, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention.
  • program code When implemented on a general-purpose processor, the program code segments combine with the processor to provide a unique device that operates analogously to specific logic circuits.
  • the present invention can also be embodied in the form of a bitstream or other sequence of signal values electrically or optically transmitted through a medium, stored magnetic-field variations in a magnetic recording medium, etc., generated using a method and/or an apparatus of the present invention.
  • the term “compatible” means that the element communicates with other elements in a manner wholly or partially specified by the standard, and would be recognized by other elements as sufficiently capable of communicating with the other elements in the manner specified by the standard.
  • the compatible element does not need to operate internally in a manner specified by the standard.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
US13/399,216 2011-02-17 2012-02-17 Apparatus and method for controlling handover to prevent femtocell interference Abandoned US20120214495A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US14/329,114 US9241290B2 (en) 2011-02-17 2014-07-11 Apparatus and method for controlling handover to prevent femtocell interference

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2011-0014199 2011-02-17
KR1020110014199A KR101391838B1 (ko) 2011-02-17 2011-02-17 펨토셀 간섭을 고려한 핸드오버 제어 방법 및 장치

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US14/329,114 Continuation US9241290B2 (en) 2011-02-17 2014-07-11 Apparatus and method for controlling handover to prevent femtocell interference

Publications (1)

Publication Number Publication Date
US20120214495A1 true US20120214495A1 (en) 2012-08-23

Family

ID=46653161

Family Applications (2)

Application Number Title Priority Date Filing Date
US13/399,216 Abandoned US20120214495A1 (en) 2011-02-17 2012-02-17 Apparatus and method for controlling handover to prevent femtocell interference
US14/329,114 Active US9241290B2 (en) 2011-02-17 2014-07-11 Apparatus and method for controlling handover to prevent femtocell interference

Family Applications After (1)

Application Number Title Priority Date Filing Date
US14/329,114 Active US9241290B2 (en) 2011-02-17 2014-07-11 Apparatus and method for controlling handover to prevent femtocell interference

Country Status (3)

Country Link
US (2) US20120214495A1 (ko)
KR (1) KR101391838B1 (ko)
WO (1) WO2012111907A1 (ko)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8340657B2 (en) * 2011-04-08 2012-12-25 Lg Electronics Inc. Method for transceiving signal in mobile station in multiple antenna wireless communication system and apparatus therefor
US20140221009A1 (en) * 2012-02-29 2014-08-07 Tencent Technology (Shenzhen) Company Limited Method, system and apparatus for collecting location information
US20140378143A1 (en) * 2012-02-29 2014-12-25 Huawei Technologies Co., Ltd. Method for controlling multimode radio communications system, control server and terminal
US20150011229A1 (en) * 2012-01-17 2015-01-08 Nec Corporation Wireless communication system, transmission power control apparatus, base station apparatus, parameter providing apparatus, and transmission power control method
US20150189562A1 (en) * 2012-07-17 2015-07-02 Nec Corporation Mobile communication system, wireless station, mobile communication control method, and non-transitory computer-readable medium stored with mobile communication control program
US20150358923A1 (en) * 2013-01-15 2015-12-10 Nokia Solutions And Networks Oy Methods and Apparatus
CN106304210A (zh) * 2015-05-29 2017-01-04 深圳富泰宏精密工业有限公司 网络连接控制系统及智能终端
US20170164251A1 (en) * 2014-06-05 2017-06-08 Nec Corporation Gateway device, femtocell-use base station, communication system, communication method, and storage medium
US20210067977A1 (en) * 2014-09-24 2021-03-04 Sony Corporation Telecommunications apparatus and methods
US11166205B2 (en) * 2019-11-22 2021-11-02 Cisco Technology, Inc. Neighbor lists for use in multi-operator core network based neutral host networks
US11206548B2 (en) * 2018-06-29 2021-12-21 Verizon Patent And Licensing Inc. Method and system for supporting voice calls in 5G new radio environments

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101966911B1 (ko) * 2013-03-05 2019-04-08 에스케이텔레콤 주식회사 기지국제어장치 및 기지국제어장치의 동작 방법
KR101838840B1 (ko) * 2014-05-09 2018-03-14 후지쯔 가부시끼가이샤 무선 통신 시스템, 기지국 및 단말기
CN105682106B (zh) * 2014-11-18 2019-01-18 中国移动通信集团上海有限公司 一种多制式兼容的室内覆盖设计方法及装置
US9743330B2 (en) * 2015-08-21 2017-08-22 Qualcomm Incorporated Methods and apparatus for reducing handover signaling during wireless communication procedures
US10531500B2 (en) 2016-06-02 2020-01-07 Raytheon Company Self-configuring backbone for mobile ad-hoc networks (MANETs)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090137251A1 (en) * 2007-11-27 2009-05-28 Baowei Ji Calculation and broadcast of cell-load ratio and intelligent cell selection for IEEE802.16M
US20090239533A1 (en) * 2008-03-21 2009-09-24 Interdigital Patent Holdings, Inc. Method and apparatus for searching for closed subscriber group cells
US20100015921A1 (en) * 2008-07-15 2010-01-21 Qualcomm Incorporated Wireless communication systems with femto cells
US20100173631A1 (en) * 2009-01-05 2010-07-08 Hongseok Kim Method of managing network traffic within a wireless network
US20110013600A1 (en) * 2009-07-15 2011-01-20 Electronics And Telecommunications Research Institute Method of transmitting data for reducing interference in hierarchical cell structure
US20110014920A1 (en) * 2008-02-08 2011-01-20 Telefonaktiebolaget Lm Ericsson (Publ) Method and Node in a Communications Network

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100593476B1 (ko) 1999-08-09 2006-06-28 에스케이 텔레콤주식회사 중첩셀 구조에서 상위셀과 하위셀간의 핸드오프 방법
US8089855B2 (en) 2004-06-04 2012-01-03 Qualcomm Incorporated Transmission of overhead information for broadcast and multicast services in a wireless communication system
US7835740B2 (en) 2006-12-18 2010-11-16 Alcatel-Lucent Usa Inc. Establishing cell codes for picocells within a macrocell
US8605801B2 (en) 2008-05-20 2013-12-10 Qualcomm Incorporated Pilot signal set management in a multi-carrier communication system
KR100989197B1 (ko) 2008-07-21 2010-10-20 주식회사 케이티 펨토셀 식별정보 할당을 위한 장치 및 방법
JP4465020B2 (ja) 2008-09-26 2010-05-19 株式会社エヌ・ティ・ティ・ドコモ 移動局及び無線基地局
KR20100046492A (ko) 2008-10-27 2010-05-07 주식회사 케이티 인터 ｒａｔ를 이용한 핸드오버 처리 방법 및 이에 이용되는 이동통신 단말 장치
KR101770822B1 (ko) 2009-02-22 2017-08-24 엘지전자 주식회사 무선 통신 시스템에서 인터 워킹 신호 전송 방법 및 장치
KR101587020B1 (ko) * 2009-06-10 2016-01-21 에스케이 텔레콤주식회사 핸드오버 방법과 펨토셀 기지국

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090137251A1 (en) * 2007-11-27 2009-05-28 Baowei Ji Calculation and broadcast of cell-load ratio and intelligent cell selection for IEEE802.16M
US20110014920A1 (en) * 2008-02-08 2011-01-20 Telefonaktiebolaget Lm Ericsson (Publ) Method and Node in a Communications Network
US20090239533A1 (en) * 2008-03-21 2009-09-24 Interdigital Patent Holdings, Inc. Method and apparatus for searching for closed subscriber group cells
US20100015921A1 (en) * 2008-07-15 2010-01-21 Qualcomm Incorporated Wireless communication systems with femto cells
US20100173631A1 (en) * 2009-01-05 2010-07-08 Hongseok Kim Method of managing network traffic within a wireless network
US20110013600A1 (en) * 2009-07-15 2011-01-20 Electronics And Telecommunications Research Institute Method of transmitting data for reducing interference in hierarchical cell structure

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8340657B2 (en) * 2011-04-08 2012-12-25 Lg Electronics Inc. Method for transceiving signal in mobile station in multiple antenna wireless communication system and apparatus therefor
US20150011229A1 (en) * 2012-01-17 2015-01-08 Nec Corporation Wireless communication system, transmission power control apparatus, base station apparatus, parameter providing apparatus, and transmission power control method
US9655055B2 (en) * 2012-01-17 2017-05-16 Nec Corporation Wireless communication system, transmission power control apparatus, base station apparatus, parameter providing apparatus, and transmission power control method
US10383104B2 (en) 2012-02-29 2019-08-13 Huawei Technologies Co., Ltd. Methods for controlling multimode radio communications system, control server and terminal
US20140221009A1 (en) * 2012-02-29 2014-08-07 Tencent Technology (Shenzhen) Company Limited Method, system and apparatus for collecting location information
US20140378143A1 (en) * 2012-02-29 2014-12-25 Huawei Technologies Co., Ltd. Method for controlling multimode radio communications system, control server and terminal
US9832765B2 (en) * 2012-02-29 2017-11-28 Huawei Technologies Co., Ltd. Method for controlling multimode radio communications system, control server and terminal
US9398504B2 (en) * 2012-07-17 2016-07-19 Nec Corporation Mobile communication system, wireless station, mobile communication control method, and non-transitory computer-readable medium stored with mobile communication control program
US20150189562A1 (en) * 2012-07-17 2015-07-02 Nec Corporation Mobile communication system, wireless station, mobile communication control method, and non-transitory computer-readable medium stored with mobile communication control program
US20150358923A1 (en) * 2013-01-15 2015-12-10 Nokia Solutions And Networks Oy Methods and Apparatus
US9967834B2 (en) * 2013-01-15 2018-05-08 Nokia Solutions And Networks Oy Methods and apparatus for control messages in overlapping cells
US20170164251A1 (en) * 2014-06-05 2017-06-08 Nec Corporation Gateway device, femtocell-use base station, communication system, communication method, and storage medium
US20210067977A1 (en) * 2014-09-24 2021-03-04 Sony Corporation Telecommunications apparatus and methods
US11671841B2 (en) * 2014-09-24 2023-06-06 Sony Corporation Telecommunications apparatus and methods
CN106304210A (zh) * 2015-05-29 2017-01-04 深圳富泰宏精密工业有限公司 网络连接控制系统及智能终端
US11206548B2 (en) * 2018-06-29 2021-12-21 Verizon Patent And Licensing Inc. Method and system for supporting voice calls in 5G new radio environments
US11889318B2 (en) 2018-06-29 2024-01-30 Verizon Patent And Licensing Inc. Method and system for supporting voice calls in 5G new radio environments
US11166205B2 (en) * 2019-11-22 2021-11-02 Cisco Technology, Inc. Neighbor lists for use in multi-operator core network based neutral host networks

Also Published As

Publication number Publication date
KR101391838B1 (ko) 2014-05-07
KR20120094748A (ko) 2012-08-27
US9241290B2 (en) 2016-01-19
WO2012111907A1 (ko) 2012-08-23
US20140323134A1 (en) 2014-10-30

Similar Documents

Publication Publication Date Title
US9241290B2 (en) Apparatus and method for controlling handover to prevent femtocell interference
US9055498B2 (en) Handover in long term evolution network
US10911960B2 (en) Frequency allocation method and device for unauthorized frequency band
US9491769B2 (en) Method and system for implementing mobile relay
US9014146B2 (en) Network redirection in heterogeneous overlay networks
US20130273878A1 (en) Apparatus for improved mobility in a wireless heterogeneous network
US8831619B2 (en) Method of sharing information between base stations associated with different network technologies and the base stations
KR20110084415A (ko) 사용자 기기와 주 펨토셀을 연관시키기 위한 방법
KR20110066217A (ko) 이벤트-트리거링된 측정 보고를 이용하여 매크로셀에서 펨토셀로의 위치-기반 핸드오버들
EP3611968B1 (en) Base station and method
US11012871B2 (en) Apparatus and method
US20110142004A1 (en) Small base station apparatus and cell search method
US20130210444A1 (en) Network element, cellular communication system and method therefor
WO2022228559A1 (zh) 小区重选的方法、通信装置和计算机可读存储介质
CN108282905B (zh) 一种随机接入方法及其网元
WO2020199060A1 (zh) 网络接入方法及相关设备
EP2974452B1 (en) Methods and apparatus for handover management
WO2013059996A1 (en) Spectrum sensing
CN102202398A (zh) 一种异构网络的载波资源配置方法及装置
KR101218516B1 (ko) 컴포넌트셀 기지국 및 그 동작 방법
US11477637B2 (en) Communication system
US9565606B2 (en) Controlling signal transmission in radio units
Nguyen et al. Uplink channel allocation scheme and qos management mechanism for cognitive cellular-femtocell networks
CN112929989A (zh) 接入小区选定方法、模块、核心网系统和计算机可读介质
KR20160036415A (ko) 기지국장치 및 기지국장치의 동작 방법

Legal Events

Date Code Title Description
AS Assignment

Owner name: KT CORPORATION, KOREA, REPUBLIC OF

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHOI, BYOUNG-JIN;BAN, TAE-WON;AHN, CHANG-YONG;AND OTHERS;SIGNING DATES FROM 20120212 TO 20120216;REEL/FRAME:027723/0651

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION