Classifications

• • 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
  • H04W36/26—Reselection being triggered by specific parameters by agreed or negotiated communication parameters
• • 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
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/50—Allocation or scheduling criteria for wireless resources
  • H04W72/56—Allocation or scheduling criteria for wireless resources based on priority criteria

Definitions

• the present invention relates to a layer 2 (L2) handover method according to traffic types, and more specifically, to an L2 handover method having respective handover determination threshold value values according to traffic types in a mobile communication system supporting multi-services.
• L2 layer 2
• a handover (or handoff) is performed by switching a communication channel to another channel of a new cell in order to maintain communication when a mobile station moves from a base station (or a sector) to another base station.
• the handover is classified as a hard handover and a soft handover.
• the hard handover results in a radio connection being broken between the network and the mobile station before a new radio connection is established with the network in a target cell, while the soft handover is a handover procedure in which radio links are added and abandoned in such a manner that the mobile station always maintains at least one radio link established with the base station.
• layer 3 (L3) handover in an IP layer and a layer 2 (L2) handover in layers below the IP layer.
• layer 2 (L2) will be referred to as a data link layer
• layer 3 (L3) will be referred to as a network layer.
• This patent relates to a handover method for allocating a call to a processor having minimum available resources among processors having more resources than required by a mobile station, and an apparatus using the handover method.
• a call access rate may be increased since the handover to base stations having a carrier to interference noise ratio (CINR) satisfying requirements that are provided based on handover determination reference information is notified to a service base station when at least one CINR satisfies the requirements, and accordingly, a call drop rate may be reduced.
• CINR carrier to interference noise ratio
• This patent relates to a handover method for preventing data loss by minimizing a handover delay time in a mobile communication network while supporting mobility on IP-based networks.
• an IP address is reallocated according to a process of mobile IPs to perform a location registration process when a terminal is in an idle state, data loss may be prevented by using a retransmission function of a radio link control (RLC) layer since the mobile terminal sends traffic to a new access station (AS) rather than performing an IP address registration process, and a network load may be reduced since some processes for IP allocation are omitted.
• RLC radio link control
• non-real-time traffic such as World Wide Web (WWW) traffic and email are not sensitive to packet delay but are sensitive to packet loss. Accordingly, the packet loss may be reduced since the non-real-time traffic stores packets transmitted during handover in a packet retransmission method or a buffering method, and transmits the stored packets after layer 2 (L2) handover is finished. Therefore, QoS deterioration may be also reduced.
• WWW World Wide Web
• L2 layer 2
• the present invention has been made in an effort to provide a layer 2 (L2) handover method that satisfies quality of service (QoS) requirements and has respective handover determination threshold values according to traffic types in a mobile com- munication system supporting multi-services, and to provide a layer 2 (L2) handover method for respectively providing differentiated services according to sensitiveness to delay and minimizing call drop between a mobile terminal and a base station which is caused by a handover in the layer 2 (L2).
• QoS quality of service
• L2 layer 2
• QoS quality of service
• a) a signal strength for each traffic class is measured
• b) respective handover determination reference values according to traffic class types are applied and an L2 handover call is determined
• c) resources are allocated to services that are sensitive to delay before services that are insensitive to delay so as to satisfy the QoS requirements for the determined handover calls.
• a handover region is varied according to multi-traffic class services having different priorities from each other.
• the high priority traffic class service among the multi-traffic class services has a wide handover region so as to preferentially perform the handover since it has a high handover threshold value.
• FlG. 1 shows a flowchart for representing a layer 2 (L2) handover according to traffic type according to an exemplary embodiment of the present invention.
• FlG. 2 shows a detailed flowchart for representing an L2 handover call determination process according to the exemplary embodiment of the present invention.
• FlG. 3 shows a diagram for representing parameters used when a handover call is determined in a multi-traffic class service environment according to the exemplary embodiment of the present invention.
• FlG. 4 shows a schematic diagram for representing a handover region of the multi- traffic class service having various priorities according to the exemplary embodiment of the present invention. Best Mode for Carrying Out the Invention
• the L2 handover method will be described by using one of four service classes recommended in a universal mobile telecommunications system (UMTS) as follows.
• UMTS universal mobile telecommunications system
• Class 1 is a conversational class for voice or video conference traffic
• Class 2 is a streaming class for real-time video streaming
• Class 3 is an interactive class for World Wide Web (WWW) or data access
• Class 4 is a background class for email or downloading.
• Class 1 and Class 2 correspond to real-time services and Class 3 and Class 4 correspond to non-real-time services.
• FlG. 1 shows a flowchart for representing a layer 2 (L2) handover operation according to traffic type according to an exemplary embodiment of the present invention.
• the L2 handover operation includes handover call determination processes (SlOO and S200) and a call admission control process (S300).
• a signal strength P J for each traffic class is measured in step SlOO.
• i of P J denotes a traffic class and j thereof denotes a base station number.
• an L2 handover call is determined in step S200 by using a handover determination reference value varied according to a traffic class type. That is, after signal strength between a handover candidate cell and a terminal is measured, a handover call to a target cell is determined by using the handover determination reference value varied according to the traffic class type of a corresponding terminal.
• a call admission control process is performed, in which resources are preferentially allocated to services that are sensitive to delay before services that are insensitive to delay so as to satisfy the QoS requirements for the determined handover calls. That is, the handover call handed over to the target cell requests resource allocation, and it is determined whether resources for the required handover call are allocated in various call admission control methods in step S300. At this time, it is determined whether a terminal having an i traffic class is admitted as a result of the call admission control to the handover cell.
• the handover call determined in step S200 performs the call admission control process before the resource allocation requested by a new call is performed.
• the steps SlOO to 300 are repeatedly performed.
• the reconfiguration method is a representative method among conventional call admission control methods of a mobile communication system.
• minimum and maximum bandwidths satisfying the QoS requirements in the traffic classes are previously allocated.
• the bandwidth of various services may be varied from a maximum value to a minimum value by using the reconfiguration method. That is, an operation obtaining bandwidth from services having low priority or lending bandwidth to a service having high priority is performed according to resource usages at an arbitrary moment.
• a new service continues at a minimum bandwidth when the new service does not obtain a maximum bandwidth in an arbitrary base station cell.
• the high priority service deprives bandwidth by reducing the bandwidth of the service having lower priority to a minimum quality level of bandwidth.
• a final handover call is determined in step S400.
• the traffic class i and the base station cell number j are selected.
• FIG. 2 shows a detailed flowchart for representing the L2 handover call determination process corresponding to step S200 shown in FIG. 1 according to the exemplary embodiment of the present invention.
• the L2 handover call determination process shown in FIG. 2 is based on appropriate handover parameter establishment for performing the handover operation.
• P denotes a signal strength for the traffic class i, and the signal strength includes a signal to noise ratio (SNR) which is presented in Dm.
• SNR signal to noise ratio
• H denotes a handover threshold value for the traffic class i.
• the signal strength indicates that the mobile terminal enters a handover region when the signal strength is less than a corresponding handover threshold value H .
• Q denotes a quality threshold value for the traffic class i.
• the quality threshold value indicates an acceptable minimum quality value during an active call period. Therefore, the signal strength indicates that the mobile terminal leaves the handover region when the signal strength is less than a corresponding quality reference Q .
• [44] D denotes a determination value for the traffic class i.
• the handover threshold value H a distance ⁇ between the mobile terminal and the base station is calculated (at this time, the distance ⁇ corresponds to a time of the mobile terminal moving to the handover region).
• the signal strength corresponds to quality threshold value Q
• a distance ⁇ between the mobile terminal and the base station is calculated (at this time, the distance ⁇ corresponds to a time of the mobile terminal leaving the handover region). Therefore, the handover determination threshold value D is appropriately determined between ⁇ and ⁇ .
• step S210 and the traffic class i is increased by 1 in step S202.
• step S203 it is determined whether the signal strength P for the traffic class i is less than a corresponding handover threshold value H in step S203, and the handover is started in step S204 at the distance ⁇ between the mobile terminal and the base station since the mobile terminal enters the handover region when the signal strength P for the traffic class i is less than the handover threshold value H .
• the traffic class i is increased by 1 in step S202.
• step S205 it is determined whether the signal strength P for the traffic class i is less than the handover determination threshold value D for the traffic class i in step S205, and the handover is determined in step S206 where the distance between the mobile terminal and the base station reaches D when the signal strength P for the traffic class i is less than handover determination threshold value D for the traffic class i.
• the traffic class i is increased by 1 in step S202.
• step S207 it is determined whether the signal strength P for the traffic class i is less than a corresponding quality threshold value Q in step S207, the handover is finished at the distance ⁇ where the mobile station leaves the handover region when the signal strength P for the traffic class i is less than the corresponding quality threshold value Q , and a call admission for the handover call is requested to perform the handover in the target cell in step S208.
• the traffic class i is increased by 1 in step S202.
• the handover call to the target cell is determined by using the handover determination reference value that is varied according to various traffic types including class 1 to class 4.
• FlG. 3 shows a diagram for representing parameters used when the handover call is determined in a multi-traffic class service environment according to the exemplary embodiment of the present invention, and it shows various handover determination parameters according to the traffic classes in the multi-traffic class environment.
• the handover threshold values H and H and the handover determination threshold values D and D for the traffic classes 0 and 1 may be found
• a handover exit point of the traffic class 1 may be found according to the handover threshold values H and H and the handover determination threshold values D and D , and handover margins for the traffic classes 0 and 1 according to 1), 2), 3), 4), 5), and 6) may be found.
• a high priority traffic service among the multi-class services i.e., the traffic class 0 in FlG. 3
• has a wide handover region so as to preferentially perform the handover.
• the signal strength between the handover candidate cell and the mobile terminal is measured as described above, and the services that are sensitive to delay receive resources before the services that are insensitive to delay in order to effectively use the resources and to satisfy the QoS requirements in the call admission control method (e.g., the reconfiguration method) after the handover call to the target cell is determined.
• the call admission control method e.g., the reconfiguration method
• FIG. 4 shows a schematic diagram for representing the handover region of the multi-traffic class service having various priorities according to the exemplary embodiment of the present invention, and the handover region is determined by the parameters shown in FlG. 3.
• the resources are basically allocated to the high priority service class that is sensitive to delay before the low priority service class that is insensitive to delay.
• the handover region become wide as shown in FlG. 4. Accordingly, more service classes that are sensitive to delay are registered in a handover candidate list than the service classes that are insensitive to delay and are easily included in a call admission control list, which supports a basic policy of the call admission control.
• a high threshold value is provided to the high priority services and a low threshold value is provided to the low priority services, since the threshold values are respectively established for the respective service classes according to characteristics of the multi-services having respective QoS requirements in the multi-service environment, and a low call drop rate is maintained since a service interruption caused by deterioration of the QoS between the mobile terminal and the base station is prevented while the handover is performed. Accordingly, no resources are wasted since the various traffic classes satisfy the QoS requirements according to the exemplary embodiment of the present invention.
• the resources may be effectively allocated since the QoS criteria including the handover failure rate and the packet loss rate respectively required for the respective traffic classes in the multi-class service environment are satisfied.

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

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Cited By (7)

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Citations (6)

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• 2004
  • 2004-12-06 KR KR1020040101950A patent/KR100651033B1/ko not_active IP Right Cessation
• 2005
  • 2005-11-28 EP EP05820726A patent/EP1820366A4/en not_active Withdrawn
  • 2005-11-28 WO PCT/KR2005/004021 patent/WO2006062306A1/en active Application Filing

Patent Citations (6)

Non-Patent Citations (1)

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