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
  • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/08—Reselecting an access point
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/24—Reselection being triggered by specific parameters
  • H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
  • H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/34—Reselection control
  • H04W36/38—Reselection control by fixed network equipment
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
  • H04W72/044—Wireless resource allocation based on the type of the allocated resource
  • H04W72/0466—Wireless resource allocation based on the type of the allocated resource the resource being a scrambling code
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/50—Allocation or scheduling criteria for wireless resources
  • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/20—Manipulation of established connections
  • H04W76/27—Transitions between radio resource control [RRC] states
• • 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

Definitions

• the present invention relates to a method for handling communication between a user equipment (UE) and a radio network controller (RNC).
• UE user equipment
• RNC radio network controller
• the user equipment and the radio network controller have to determine common transfer parameters, like a common carrier frequency for sending and receiving Radio
• RRC Resource Control
• Typical macro cells are radio cells of the UMTS Terrestrial Radio Access Network (UTRAN) or the GSM/EDGE Radio Access Network (GERAN).
• the local access networks are pico- or femtocells, for instance. These local access networks cover small areas compared to the macro cells, such as in trains, aircrafts, ferries and building, like offices, private houses, shopping malls, train stations, airports and the like.
• a suchlike femtocell is discloses in US patent application 2009 / 0 092 122 A1.
• the above mentioned local access networks operate in parallel to the macro cells. As a result, there is usually a certain overlap between the local access network and the access network of the macro cells.
• a data transfer between the radio network controller of the macro cell and the user equipment could potentially be disturbed by interference with the local access network (referred to as co-channel interference).
• co-channel interference a data transfer between the radio network controller of the macro cell and the user equipment could potentially be disturbed by interference with the local access network.
• co-channel interference referred to as co-channel interference.
• the carrier frequency for data transfers between the user equipment and the radio network controller is in the proximity of a frequency which is allowed for access to the local area network.
• An access to a femto network is not allowed, when the maximum amount of mobile devices in the femto network has already been reached, for instance.
• Suchlike co-channel interference between the femto network and the macro network results in a "dead-zone" for "non-femto" user equipment in close proximity to the femto network and a "grey-zone” at the edge of femto coverage where macro quality can still be impaired.
• the interfered macro base transceiver station or Node B
• the radio network controller is not aware of the interference that "non-femto" user equipment may be experiencing near a disallowed femto network.
• the radio network controller has the option to redirect individual user equipment to a different UTRA cell by specifying the IE (information element)
• Radio Bearer Reconfiguration message "Frequency info" in the RRC connection setup or Radio Bearer Reconfiguration message, respectively.
• the radio network controller does not know if individual user equipment cannot or should not use that other frequency due to interference from the femto network.
• the target frequency of the RRC connection setup or the Radio Bearer Reconfiguration message is interfered by the local access network, the user equipment is not able to answer the radio network controller on the target frequency. Consequently, the radio network controller has to generate an additional RRC connection setup (and prior the user equipment has to transmit an additional connection request, respectively) or the radio network controller has to transmit a further Radio Bearer Reconfiguration message each concerning the clear frequency. This adds delay to the call setup time or to the Radio Bearer Reconfiguration time, each time.
• An object of the present invention is to provide a method for handling communication between user equipment and a radio network controller, as well as a program and a computer program product for controlling a radio network controller to prevent redirection of the user equipment to co-channel frequencies interfered by the local access network.
• the object of the present invention is achieved by a method for handling communication between a user equipment and a radio network controller, as well as a program and a computer program product for controlling a radio network controller, the method comprising the steps of providing a transmission instruction by the radio network controller for redirecting the user equipment to a certain target carrier frequency, evaluating if the target carrier frequency is interfered by a local access radio network near the user equipment and preventing a redirection of the user equipment to the target carrier frequency by the radio network controller for a certain time period, if the target carrier frequency is interfered by the local access network near the user equipment.
• the radio network controller identifies a user equipment which is not able to operate on the directed target carrier frequency due to interference with a local access area network.
• a redirection of the user equipment to the target carrier frequency is prevented for the certain time period, so that a communication between the user equipment and the radio network controller via a clear frequency is maintained.
• the risk of time delays, quality disturbance, call drops, ping-pong handovers and interference into the local access network coverage can securely be avoided.
• the target carrier frequency preferably features a frequency allowed for access to the local access network.
• the corresponding parameters of the local access network like frequencies and scrambling codes, have to be provided to the radio network controller.
• the local access network comprises a femto cell and the target carrier frequency comprises an allowed femto frequency for the femto cell, wherein the transmission instruction is generated in such a manner, that a redirection of the user equipment to a target carrier frequency used by the femto cell is prevented, when the user equipment is located in the proximity of the femto cell and does not have access to the femto cell.
• the transmission instruction comprises a connection setup transmitted from the radio network controller to the user equipment, wherein the step of providing the transmission instruction is caused by a first connection request transmitted from the user equipment to the radio network controller and wherein the step of evaluating if the target carrier frequency is interfered by the local access radio network near the user equipment comprises a step of detecting if a second connection request of the user equipment is received by the radio network controller after transmitting a
• the term "the second connection request is effectively equal to the first connection request” means that the second connection request is a duplicate RRC connection request from the User Equipment (UE).
• UE User Equipment
• the radio network controller detects the second connection request of the same user equipment, shortly after the radio network controller transmitted a connection setup to the user equipment with a target frequency allowed for access to the local access network as a result of a preceding first connection request of the user equipment (which is equal to the second connection request), the radio network controller is able to identify this user equipment as a "non-femto" user equipment (user equipment with no access to the local access network). Consequently, the radio network controller "knows" that the non-femto user equipment is located in the "grey-zone” or in the "dead-zone" of the femto network and beneficially prevents further redirection of this user equipment to the target frequency for a certain time period.
• the transmission instruction comprises a Radio Bearer Reconfiguration message for the user equipment
• the step of evaluating if the target carrier frequency is interfered by the local access radio network near the user equipment comprises a step of detecting if one or more unsuccessful Radio Bearer Reconfiguration messages have been subsequently transmitted to the user equipment for redirecting the user equipment to the target carrier frequency.
• the radio network controller does not receive a message from the user equipment that a Radio Bearer Reconfiguration has been successfully performed by the user equipment, shortly after the radio network controller transmitted one or more Radio Bearer Reconfiguration message with a target frequency allowed for access to the local access network, the radio network controller is able to identify this user equipment as a user equipment located near or inside the service area of the local access network (e.g. "non-femto" UE in "grey- zone” or "dead-zone”). Consequently, the radio network controller is capable of preventing further redirection of this user equipment to the target frequency for a certain time period.
• the step of evaluating if the target carrier frequency is interfered by the local access radio network near the user equipment comprises a step of detecting if the user equipment performs a certain number of ping-pong inter-frequency handovers from a clear carrier frequency to the target carrier frequency and back from the target carrier frequency to the clear frequency.
• the radio network controller is able to detect that the user equipment remains in the "grey-zone" of the local access network.
• the method comprises a step of initiating inter-frequency measurements performed by the user equipment concerning the target carrier frequency and the scrambling codes of the local access radio network and a step of evaluating a signal strength and/or a signal quality in the inter-frequency measurements of the user equipment.
• the risk of interference between the local access network and the target frequency can directly be derived from the measurements performed by the user equipment.
• these steps are performed, after the radio network controller detects that the target carrier frequency is at least temporarily interfered by the local access radio network, particularly by detecting inter-frequency handovers or an unsuccessful Radio Bearer Reconfiguration, as mentioned above.
• the radio network controller is able to assess if the user equipment is in the "dead-zone" (inside the service area of the local access radio network) or in the "grey-zone” (near the service area of the local access radio network) of the local access network. If the user equipment is located in the "dead- zone" a longer time period for preventing a redirection of the user equipment to the target frequency could be provided compared to the time period related to the "grey- zone", for instance.
• the redirection of the user equipment to the target frequency is prevented for a certain time period and in particular for a certain hysteresis time.
• the hysteresis time is a static value or depends on certain parameters, wherein the parameters preferably comprises a nominal hysteresis time, a recent mobility history of the user equipment, a signal strength and quality concerning the target carrier frequency and scrambling codes of the local access radio network and/or the like.
• the length of the time period can be adapted to individual needs.
• the time period is provided in dependency of a recent mobility history of the user equipment.
• Another object of the present invention is a program for controlling a radio network controller, wherein the program provides a transmission instruction for redirecting a user equipment to a certain target carrier frequency and evaluates if the target carrier frequency is interfered by a local access radio network, wherein a redirection to the target carrier frequency is prevented for a certain time period, if an interference between the local access network near the user equipment and the target carrier frequency is detected.
• the program instructs the radio network controller to perform the above mentioned method in order to achieve the above mentioned advantages in comparison to the state of the art.
• Another object of the present invention is a computer program product comprising a program controlling a radio network controller as mentioned above.
• Figure 1 illustrates schematically an example architecture of a
• Figure 2 illustrates schematically a call flow between user equipment and a radio network controller according to an exemplary embodiment of the present invention.
• Figure 3 illustrates schematically the call flow between user equipment and a radio network controller according to another exemplary embodiment of the present invention.
• FIG. 1 an exemplary architecture of a conventional UMTS Terrestrial Radio Access (UTRA) network comprising macro cells 20 and a local radio access network 4 is illustrated.
• the local radio access network 4 is integrated into a home 21 and coupled to the core network 100 of the UMTS Terrestrial Radio Access network.
• the UMTS Terrestrial Radio Access network comprises a radio network controller 3 connected with the core network 100 and coupled to base transceiver stations 22 (BTS or Node B) of the cellular service provider providing the macro cells 20 for the cellular mobile network.
• BTS base transceiver stations 22
• Each base transceiver station 22 contains radio frequency transmitters and receivers used to communicate directly with user equipment 2', like cellular phones, notebooks and the like, which move freely around it.
• the term "local radio access network” include typical definitions of femto cells, home base stations, personal access points (PAPs) and personal 3G base stations, as known from the prior art.
• the local access radio network 4 features a femto cell 4' with a local femto cell access point base station 23 which is connected to the core network 100.
• the local femto access point base station 23 may operate to receive wireless communication from allowed user equipment 2" in the home 21 and provide corresponding communication with the core network 100 via an IP wide area network, for instance.
• Figure 1 illustrates schematically certain user equipment 2, particularly a cellular phone 2, near the femto cell 4' which has no access to the femto network 4'.
• the access is not allowed because the maximum amount of devices 2" in the femto network 4 has already been reached, for instance. Consequently, a data transfer from the cellular phone 2 to the core network 100 via the local femto cell access point base station 23 is not permitted.
• the data transfer 24 between the radio network controller 3 and the mobile phone 2 can be disturbed due to co-channel interference between the frequencies of the femto cell 4 and a certain carrier frequency for the data transfer 24 between the radio network controller 3 and the mobile phone 2 (the target frequency 11 ).
• the cellular phone 2 which has no access to the femto network 4' can be located in a "dead-zone" in close proximity to the femto network 4 1 or in a "grey-zone" at the edge of the femto coverage where macro quality can still be impaired.
• the interfered macro base transceiver stations 22 will have at least one other clear frequency 10 to serve the affected "non-femto" cellular phone 2.
• the problem in the state of the art is that the radio network controller 3 is not aware of the interference that "non-femto" cellular phone 2 may be experiencing near a disallowed femto network 4'.
• the radio network controller 3 performs a step of evaluating if a directed target carrier frequency 11 is interfered by the local access radio network 4 near the user equipment 2. Consequently, further redirection of the cellular phone 2 to a target carrier frequency 11 which interferes with the femto cell 4' is prevented by the radio network controller 3 for a certain time period and the data transfer 24 between the cellular phone 2 and the UTRA network based on the clear frequency is provided.
• FIG. 2 illustrates schematically a call flow 1 of a method according to the present invention, wherein the call flow 1 between user equipment 2, particularly a cellular phone 2, and a radio network controller 3 according to the architecture of figure 1 is shown.
• the cellular phone 2 has no access to the femto cell 4', but is located near (in the "grey-zone" respectively) of the femto cell 4'.
• the radio network controller 3 has the option to redirect the cellular phone 2 to a different UTRA cell by specifying the IE "Frequency info" in the RRC connection setup or a Radio Bearer Reconfiguration message.
• the policy of the radio network controller 3 can include redirection the cellular phone 2 to a target frequency 11 which is an allowed frequency of the femto cell 4'.
• a target frequency 11 which is an allowed frequency of the femto cell 4'.
• this frequency 10 can be used for undisturbed data transmission 24 between the radio network controller 3 and the cellular phone 2 via the macro cell.
• This frequency 10 is referred to as the clear frequency 10.
• connection setup message 12 (also referred to as transmission instruction 12) to the cellular phone 2 using also the clear frequency 10, wherein the connection setup message 12 includes a redirection of the cellular phone 2 to a certain target frequency 11 in accordance with the policy of the radio network controller 3, wherein the target frequency 11 is an allowed frequency for the femto cell 4'.
• the target frequency 11 is disturbed by the femto cell 4', because the cellular phone 2 is located in the "grey-zone" of the femto cell 4'. Consequently, the cellular phone 2 is not able to send a connection setup complete message 15 to the radio network controller 3 on the instructed target frequency 11. Instead, the cellular phone 2 has to send again a second connection request 13' on the clear frequency 10, wherein the radio network controller 3 transmits an additional connection setup message 14 on the clear frequency 10 without redirecting the cellular phone 2 to the interfered target frequency 11. Afterwards, the cellular phone 2 is able to send the connection setup complete message 15 on the clear frequency.
• the additional second connection request 13' and the additional connection setup message 14 adds some delay to the call setup time, which is repeated every time the "non-femto" cellular phone 2 in the "grey-zone” or in "dead-zone” requests to set up an RRC connection on the clear frequency 10 and when the radio network controller policy dictates a redirection on the interfered target frequency 11.
• the radio network controller 3 performing the method and/or the program according to the present invention evaluates that the cellular phone 2 is interfered by the proximity of the femto network 4' on the target carrier frequency 11 and identifies that the cellular phone 2 is necessarily located in the "grey-zone" or in the "dead-zone" of the femto network 4'. Because otherwise, the radio network controller 3 should not receive the additional second connection request 13', shortly after transmitting the first connection setup message 12 which includes the redirection of the cellular phone 2 to the target frequency 11. Preferably, the radio network controller 3 stores this information for a certain time period to prevent redirection the cellular phone 2 to the target frequency 11 again. Advantageously, prospective time delay establishing a connection can be avoided.
• Figure 3 illustrates schematically a further call flow 1 between the radio controller network 3 and the cellular phone 2 of a method according to another embodiment of the present invention, which is quite similar to the embodiment of figure 2, wherein the radio network controller 3 transmits a Radio Bearer
• the radio network controller 3 orders a Radio Bearer Reconfiguration 16 from cell_FACH to cell_DCH, but the cellular phone 2 cannot send the Radio Bearer Reconfiguration Complete message 17 on the specified target frequency 11.
• the radio network controller 3 identifies that at the location of the user equipment 2 the target carrier frequency 11 interferes with the femto cell 4'.
• the radio network controller 3 stores this information for a certain time period to prevent an additional redirection of the cellular phone 2 to the target frequency 11 again.

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

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• 2010
  • 2010-06-16 US US13/381,134 patent/US8503939B2/en active Active
  • 2010-06-16 WO PCT/EP2010/003616 patent/WO2011000475A1/en not_active Ceased
  • 2010-06-16 MX MX2011012966A patent/MX2011012966A/es active IP Right Grant
  • 2010-06-16 CN CN201080027970.0A patent/CN102804851B/zh active Active
  • 2010-06-16 PL PL10730072T patent/PL2449815T3/pl unknown
  • 2010-06-16 ES ES10730072.5T patent/ES2551381T3/es active Active
  • 2010-06-16 BR BRPI1016006-0A patent/BRPI1016006B1/pt active IP Right Grant
  • 2010-06-16 EP EP10730072.5A patent/EP2449815B1/en active Active
  • 2010-06-16 JP JP2012516556A patent/JP5444463B2/ja active Active
  • 2010-06-16 KR KR1020127002069A patent/KR101353275B1/ko active Active
  • 2010-06-16 HU HUE10730072A patent/HUE025886T2/en unknown
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