Patent Publication Number: US-2005128972-A1

Title: Method of managing resources for high-speed packet data service in a mobile communication system

Description:
PRIORITY  
      This application claims priority under 35 U.S.C. § 119 to an application entitled “Method of Managing Resources for High-Speed Packet Data Service in a Mobile Communication System” filed in the Korean Intellectual Property Office on Nov. 13, 2003 and assigned Serial No. 2003-80355, the content of which is incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates generally to a resource management method in a mobile communication system, and in particular, to a method of managing the status of resources allocated for high-speed packet data service.  
      2. Description of the Related Art  
      Mobile communication systems have evolved from basic voice service to high-speed, high-quality wireless data packet service for providing data services and multimedia services. High-speed wireless data packet service is being standardized for 3 rd  generation (3G) mobile communication systems, asynchronous UMTS (Universal Mobile Telecommunications System) of 3GPP (3 rd  Generation Project Partnership), and synchronous CDMA (Code Division Multiple Access) of 3GPP2 (3 rd  Generation Project Partnership 2). For example, the 3GPP and the 3GPP2 are standardizing HSDPA (High Speed Downlink Packet Access) and 1xEV-DV (Evolution-Data and Voice), respectively. The standardization work is major evidence of efforts to search for a solution to 2-Mbps or above high-speed, high-quality wireless data packet transmission service in the 3G mobile communication systems. 4 th  generation mobile communication systems intend to provide higher-speed, higher-quality multimedia service.  
      HSDPA is a data transmission scheme using an HS-DSCH (High Speed-Downlink Shared CHannel) and related control channels. The HS-DSCH is a downlink data channel that supports downlink high-speed packet data transmission in a UMTS mobile communication system.  
      HSDPA requires an advanced technology that increases adaptability to channel changes, aside from traditional technologies available in existing mobile communication systems. Therefore, AMCS (Adaptive Modulation and Coding Scheme), n-channel SAW (Stop And Wait) HARQ (Hybrid Automatic Retransmission reQuest), and FCS (Fast Cell Selection) have been introduced in HSDPA.  
      However, due to limited resources, system performance varies depending on how the limited resources are managed in mobile communication systems.  
      Regarding resource management in a conventional mobile communication system, a Node B is responsible for mapping between internal logical resources and hardware resources. The logical resources include local cells, cells, common transport channels, and common physical channels.  
      Upon initialization for HSDPA, the Node B checks its internal hardware status and notifies an RNC (Radio Network Controller) of the hardware status in the form of local cell information by a RESOURCE STATUS INDICATION message. The RESOURCE STATUS INDICATION message is a No Failure message. The RNC establishes logical resources, that is, cells and common channels for the Node B by a Cell Setup procedure and a common channel setup procedure based on the reported information.  
      The established initial resource status may be changed when a configuration within the Node B is changed or some failure is sensed from hardware in the Node B. Upon a change in the resource status, the Node B reports the resource status change to the RNC by a RESOURCE STATUS INDICATION (Service Impacting) message. The change is about the statuses of local cells, cells, and common channels. The RNC deletes unavailable cells or common channels based on the report, and reallocates cells or common channels in order to switch the Node B to the reallocated cells or common channels.  
      A Node B, which supports the new scheme proposed in the future-generation mobile communication systems, HSDPA, also needs to check its hardware resource status for HSDPA and report the hardware resource status in the form of logical resource information. However, such a procedure is yet to be specified.  
     SUMMARY OF THE INVENTION  
      An object of the present invention is to substantially solve at least the above problems and/or disadvantages and to provide at least the advantages below. Accordingly, an object of the present invention is to provide a method of managing the status of allocated resources in an HSDPA mobile communication system.  
      Another object of the present invention is to provide a method of checking the configuration/status of available resources, upon initialization of hardware configured to support HSDPA and reporting the configuration/status information to an RNC in a Node B.  
      A further object of the present invention is to provide a method of checking the configuration/status of resources and reporting the resource configuration/status to an RNC, when a change or a failure occurs in hardware configured to support HSDPA.  
      Still another object of the present invention is to provide a method of reestablishing logical resources for HSDPA in a cell based on resource configuration/status information received from a Node B in an RNC.  
      Yet another object of the present invention is to provide a method of enabling an ongoing HSDPA service to be continued for a UE through a cell, when logical resources are reestablished for HSDPA.  
      Yet a further object of the present invention is to provide a method of ordering a Node B to report its HSDPA logical resource status to an RNC, when the logical resource configuration/status of the Node B is not identical to that of the RNC.  
      The above and other objects are achieved by providing a method of managing resources for HSDPA in a mobile communication system.  
      According to one aspect of the present invention, in a method of reporting the status of resources used for a high speed packet data service to an RNC in a mobile communication system in which the RNC allocates resources for the high speed packet data service and a Node B includes at least one local cell providing the high speed packet data service using the allocated resources among a plurality of local cells, the Node B determines on a local cell basis if the local cells support the high speed packet data service, and transmits to the RNC per-local cell-based availability information indicating the availability of the high speed packet data service according to the determination.  
      According to another aspect of the present invention, in a method of allocating resources for a high speed packet data service in a mobile communication system having the RNC and a Node B includes at least one local cell providing the high packet data service using the allocated resources among a plurality of local cells, the RNC receives from the Node B per-local cell-based availability information indicating availability of the high speed packet data service in the local cells, determines the maximum number of cells that support the high speed packet data service based on the per-local cell-based availability information, and allocates resources for the high speed packet data service based on the maximum cell number.  
      According to a further aspect of the present invention, in a method of reporting the status of resources used for a high speed packet data service to an RNC in a mobile communication system in which the RNC allocates resources for the high speed packet data service and a Node B provides the high speed packet data service using the allocated resources on a cell basis, the Node B detects cells that can support the high speed packet data service, counts the maximum number of cells that can support the high speed packet data service, and transmits to the RNC information indicating the maximum cell number.  
      According to still another aspect of the present invention, in a method of allocating resources for a high speed packet data service in a mobile communication system in which an RNC allocates resources for the high speed packet data service and a Node B provides the high packet data service using the allocated resources on a cell basis, the RNC receives from the Node B information indicating the maximum number of cells supporting the high speed packet data service, and allocates resources for the high speed packet data service based on the maximum cell number.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:  
       FIG. 1  is a diagram illustrating a signaling procedure between a Node B and a CRNC upon initialization of HSDPA hardware or addition/removal of an HSDPA hardware device according to the present invention;  
       FIG. 2  is a diagram illustrating a signaling procedure for a change in HSDPA hardware according to an embodiment of the present invention;  
       FIG. 3  illustrates a Node B to which the concept of HSDPA cell is applied according to the present invention;  
       FIG. 4  illustrates a cell structure according to a third embodiment of the present invention;  
       FIG. 5  is a flowchart illustrating a control operation in a Node B for reporting an HSDPA hardware change to an RNC, when a change occurs in the HSDPA hardware, according to an embodiment of the present invention;  
       FIG. 6  is a flowchart illustrating a control operation in the Node B for allocating HSDPA resources as requested by the RNC according to the embodiment of the present invention;  
       FIG. 7  is a flowchart illustrating a control operation after receiving a RESOURCE STATUS INDICATION (No Failure) message from the Node B in the RNC according to the embodiment of the present invention;  
       FIG. 8  is a flowchart illustrating a control operation after receiving a RESOURCE STATUS INDICATION (Service Impacting) message from the Node B in the RNC according to the embodiment of the present invention;  
       FIG. 9  is a flowchart illustrating a control operation in the Node B for reporting the HSDPA hardware change to the RNC, when a change occurs in HSDPA hardware, according to another embodiment of the present invention;  
       FIG. 10  is a flowchart illustrating a control operation in the Node B for allocating HSDPA resources as requested by the RNC according to the second embodiment of the present invention;  
       FIG. 11  is a flowchart illustrating a control operation after receiving a RESOURCE STATUS INDICATION (No Failure) message from the Node B in the RNC according to the second embodiment of the present invention;  
       FIG. 12  is a flowchart illustrating a control operation after receiving a RESOURCE STATUS INDICATION (Service Impacting) message from the Node B in the RNC according to the second embodiment of the present invention;  
       FIG. 13  is a flowchart illustrating an HSDPA resource allocation procedure according to the first and second embodiments of the present invention;  
       FIG. 14  is a flowchart illustrating an HSDPA resource deletion procedure according to the first and second embodiments of the present invention;  
       FIG. 15  is a flowchart illustrating the HSDPA resource switching procedure according to the first and second embodiments of the present invention;  
       FIG. 16  is a flowchart illustrating an HSDPA resource allocation procedure according to the third embodiment of the present invention; and  
       FIG. 17  is a flowchart illustrating the HSDPA resource switching procedure according to the third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Preferred embodiments of the present invention will be described in detail herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail because they would obscure the invention in unnecessary detail.  
      Additionally, for better understanding of the subject matter of the present invention, the present invention will be described in the context of a 3GPP mobile communication network being an asynchronous mobile communication standard. It is also to be appreciated that while embodiments of the present invention are applied to HSDPA, the present invention is applicable to other high-speed packet data service.  
      The present invention provides a method of managing resources used for HSDPA in a Node B. Therefore, a configuration for reporting information required for allocation of HSDPA resources to a CRNC (Controlling RNC) in a Node B, and a configuration for managing allocated HSDPA resources in an RNC are disclosed. The CRNC is an RNC for controlling logical resources to support HSDPA (hereinafter, referred to as HSDPA logical resources). The Node B reports the information required for allocation of HSDPA resources to the CRNC when (1) an HSDPA function is added to the Node B upon initialization of hardware configured to support HSDPA (hereinafter, referred to as HSDPA hardware); (2) the HSDPA function is changed due to a change in HSDPA configuration information or some failure in the HSDPA hardware in the Node B; (3) an HSDPA-related status is changed in a cell that provides the HSDPA function due to a change in the HSDPA configuration or some failure in the HSDPA hardware in the Node B; and (4) the HSDPA function of the Node B is partially or wholly lost due to removal of an HSDPA hardware device.  
      At the above-described situations, the Node B reports the current situation to the RNC controlling HSDPA logical resources. How the Node B reports to the RNC is disclosed in the different embodiments of the present invention. Each embodiment will be described with a distinction made between operations in the respective situations. A first embodiment of the present invention will be described below with reference to signaling procedures illustrated in  FIGS. 1 and 2 .  
     1. First Embodiment  
      The first embodiment utilizes a maximum number of cells (MAX_HSDPA_Cell_In_Node B) capable of supporting HSDPA (hereinafter, referred to as HSDPA cells) in a Node B. Upon initialization of HSDPA hardware, or when the ability to support HSDPA is changed due to a change in the HSDPA hardware, the Node B reports the maximum number of HSDPA cells to the RNC.  
      1.1. Signaling Procedure  
      1.1.1 Signaling when Adding/Removing HSDPA Cell  
      Upon initialization of HSDPA hardware, if the maximum number of HSDPA cells increases as the HSDPA function is added, the Node B reports the HSDPA cell increase to the RNC by a RESOURCE STATUS INDICATION (No Failure) message. If the HSDPA function is partially or wholly lost due to removal of an HSDPA hardware device, which also decreases the maximum number of HSDPA cells, the Node B reports the HSDPA cell decrease to the RNC by the RESOURCE STATUS INDICATION (No Failure) message.  
       FIG. 1  is a diagram illustrating a signaling procedure between a Node B and a CRNC upon initialization of HSDPA hardware or addition/removal of an HSDPA hardware device according to an embodiment of the present invention. Referring to  FIG. 1 , a Node B  10 , upon its initialization for HSDPA, notifies a CRNC  20  of the maximum number of HSDPA cells (Max_HSDPA_Cell_In_Node B) by a RESOURCE STATUS INDICATION (No Failure) message in step  110 . Additionally, when an HSDPA cell is added/removed due to addition/removal of an HSDPA hardware device, the Node B notifies the CRNC  20  Max_HSDPA_Cell_In_Node B by the RESOURCE STATUS INDICATION (No Failure) message in step  110 .  
      The CRNC  20  determines if an HSDPA service is to be provided through a cell, Cell x based on Max_HSDPA_Cell_In_Node B. If the HSDPA service is to be provided through Cell x, the CRNC  20  allocates HSDPA resources to the Node B by a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message in step  120 . The CRNC  20  can allocate HSDPA resources to as many HSDPA cells as indicated in the Max_HSDPA_Cell_In_Node B. That is, the number of cells that can provide the HSDPA service in the Node B  10  cannot exceed Max_HSDPA_Cell_In_Node B.  
      Upon receiving the PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message, the Node B  10  maps an internal HSDPA hardware device to Cell x in step  130 , establishes the allocated HSDPA resources. If the HSDPA resources are established successfully, the Node B transmits a PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message to the CRNC  20 .  
      The CRNC  20  has HSDPA information as illustrated in Table 1 below.  
                   TABLE 1                       Item   Number of cells                  Maximum number of HSDPA cells   MAX_HSDPA_Cell_In_NodeB       Current number of HSDPA cells   MAX_HSDPA_Cell_In_NodeB       Current number of cells to   HSDPA_Cell_In_NodeB       which HSDPA logical resources       have been allocated                  
 
      As noted from Table 1, the maximum number of HSDPA cells is equal to the current number of HSDPA cells, Max_HSDPA_Cell_In_Node B, at an initialization for HSDPA.  
      For the CRNC  20  to manage the HSDPA information as illustrated in Table 1, the Node B  10  must transmit necessary information to the CRNC  20  at its initialization for HSDPA. Table 2 below illustrates the structure of the RESOURCE STATUS INFICATION message by which the information is delivered to the CRNC  20 .  
                       TABLE 2                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       CHOICE   M       Indication Type       &gt;No Failure       &gt;&gt;Local       1 . . . &lt;max LocalCellinNodeB&gt;       Cell Information       . . . (omitted)       &gt;&gt;Local Cell       0 . . . &lt;maxLocalCellinNodeB&gt;       Group Information       . . . (omitted)       &gt;&gt;Power Local       0 . . . &lt;maxLocalCellinNodeB&gt;       Cell Group Information       . . . (omitted)       &gt;&gt; Max Number       of HSDPA Cells                  
 
      Table 2 shows that an information element (IE), Max Number of HSDPA Cells, is further included in the conventional RESOURCE STATUS INDICATION (No Failure) message so that the Node B can notify the RNC of the Max_HSDPA_Cell_In_Node B. The “Max Number of HSDPA Cells” IE indicates the maximum number of HSDPA cells available in the Node B.  
      1.1.2 Signaling Procedure in a Configuration/Status Change  
      When the ability of providing HSDPA service is changed in an HSDPA cell, the Node B  10  reports the change to the CRNC  20  by a RESOURCE STATUS INDICATION (Service Impacting) message.  
       FIG. 2  is a diagram illustrating a signaling procedure in a change in HSDPA hardware according to the embodiment of the present invention. Referring to  FIG. 2 , the Node B  10 , which has reported the HSDPA configuration/status information to the CRNC  20  at the initialization for HSDPA, monitors Cell x allocated to HSDPA logical resources in order to determine if Cell x cannot support HSDPA temporarily. Upon sensing such a situation, the Node B  10  notifies the CRNC  20  that “the HSDPA service is impossible in Cell x” or “HSDPA functionality degradation is sensed from Cell x” by a RESOURCE STATUS INDICATION (Service Impacting) message in step  210 .  
      The CRNC  20  is assumed to have the HSDPA information as illustrated in Table 1 by the afore-described procedure. Upon receiving the RESOURCE STATUS INDICATION (Service Impacting) message, the CRNC  20  updates the existing HSDPA information with the information included in the received message.  
      Table 3 illustrates an example of updating of the HSDPA information of Table 1.  
                   TABLE 3                       Item   Number of cells                  Maximum number of HSDPA cells   MAX_HSDPA_Cell_In_NodeB       Current number of HSDPA cells   MAX_HSDPA_Cell_In_NodeB-1       Current number of cells to which   HSDPA_Cell_In_NodeB       HSDPA logical resources have       been allocated                  
 
      Referring to Table 3, the current number of HSDPA cells is less than Max_HSDPA_Cell_In_Node B by the number of cells that cannot support HSDPA temporarily. Therefore, the current number of HSDPA cells is Max_HSDPA_Cell_In_Node B- 1 .  
      The CRNC  20  compares the current number of HSDPA cells with the number of cells having HSDPA logical resources. If the current number of HSDPA cells is greater than the number of cells having HSDPA logical resources, the CRNC  20  reallocates HSDPA resources to Cell x by a Physical Shared Channel Reconfiguration procedure.  
      This relation can be expressed as: “If (current number of HSDPA cells)−(current number of cells having HSDPA logical resources)≧1, HSDPA resources are allocated to Cell x which cannot support HSDPA reportedly”.  
      The Physical Shared Channel Reconfiguration procedure is performed in step  220  through step  270  in  FIG. 2 . That is, the CRNC  20  reallocates logical resources to Cell x, if the aforementioned condition is satisfied by a PHYSICAL CHANNEL RECONFIGURATION REQUEST message in step  220 . The Node B  10  then establishes the HSDPA resources for Cell x in step  260  and transmits a PHYSICAL CHANNEL RECONFIGURATION RESPONSE message to the CRNC  20  in step  270 . To establish the HSDPA resources for Cell x, a procedure for releasing existing HSDPA resources precedes in steps  230 ,  240 , and  250 . That is, the Node B  10  deletes the existing HSDPA resources for Cell x in step  230  and reports the HSDPA resource deletion to the CRNC  20  by a PHYSICAL CHANNEL RECONFIGURATION RESPONSE message in step  240 . The CRNC  20  requests establishment of the new HSDPA resources for Cell x to the Node B  10  by the PHYSICAL CHANNEL RECONFIGURATION REQUEST message in step  250 .  
      The resulting resetting of an HSDPA radio link for a UE receiving the HSDPA service via Cell x enables the ongoing HSDPA service to continue without interruptions. The CRNC  20  then notifies the UE of a change such as changed HS-PDSCH (High Speed-Physical Downlink Shared CHannel) or HS-SCCH (High Speed-Shared Control CHannel) code information (MAC-hs reset needed) by an RRC (Radio Resource Control) message, if the change occurs.  
      However, the current number of PDA cells may be less than the current number of cells having HSDPA logical resources. In this case, the CRNC  20  deletes the existing HSDPA resources for Cell x by the Physical Shared Channel Reconfiguration procedure, determining that the HSDPA service cannot be provided through Cell x in steps  220 ,  230 , and  240 . At the same time, HSDPA radio links are deleted from UEs that are receiving the HSDPA service through Cell x.  
      Table 4 shows the format of the RESOURCE STATUS INDICATION (Service Impacting) message that the Node B  10  transmits to the CRNC  20  in step  210  when the Node B  10  senses a change in its HSDPA ability during the HSDPA service.  
                       TABLE 4                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       CHOICE Indication Type   M       &gt;Service Impacting       &gt;&gt;Local Cell Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Power Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Communication Control Port Information       0 . . . &lt;maxCCPinNodeB&gt;       . . . (omitted)       &gt;&gt;Cell Information       0 . . . &lt;maxCellinNodeB&gt;       &gt;&gt;&gt;C-ID   M       &gt;&gt;&gt;Resource Operational State   O       &gt;&gt;&gt;Availability Status   O       &gt;&gt;&gt;HSDPA Information       0 . . . 1       &gt;&gt;&gt;&gt;Resource Operational State   M       &gt;&gt;&gt;&gt;Availability Status   M       &gt;&gt;&gt;HS-PDSCH Status Information       0 . . . 1       &gt;&gt;&gt;&gt;Resource Operational State   M       &gt;&gt;&gt;&gt;Availability Status   M       &gt;&gt;&gt;HS-SCCH Status Information       0 . . . 1       &gt;&gt;&gt;&gt;Resource Operational State   M       &gt;&gt;&gt;&gt;Availability Status   M                  
 
      In Table 4, HSDPA Information indicates if the HSDPA service can be provided in a corresponding cell through Resource Operational State. If Resource Operational State is Enable, the cell can provide the HSDPA service and if it is Disable, the cell cannot provide the HSDPA service. Availability Status indicates more detailed information of the HSDPA resource status. More specifically, the Availability Status is set to one of the values indicating empty, in test, failed, power-off, off-line, off-duty, dependency, degraded, no installed, and log full. These values are based on the parameters of Availability Status in section 9.2.1.2 of 3GPP Spec. 25.433. The statuses of HSDPA physical channels, HS-PDSCH and HS-SCCH, can also be reported in the format illustrated in Table 4.  
      1.1.3 Signaling Procedure for Different Configuration Information between Node B and RNC  
      If the RNC or the Node B determines that configuration/status information differs in them, an audit operation is performed. When determining that the configuration/status information of the RNC is different from that of the Node B, the Node B notifies the RNC that an audit is required by an AUDIT REQUIRED INDICATION message. The RNC then orders the Node B to conduct the audit by an AUDIT REQUEST message. In accordance with the embodiment of the present invention, upon receiving the AUDIT REQUEST message, the Node B transmits the following HSDPA information by an AUDIT RESPONSE message. 
          1) Max Number of HSDPA Cells     2) Cell Information 
            &gt;HSDPA Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
                &gt;HS-PDSCH Status Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
                &gt;HS-SCCH Status Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
               
               

      Information included for reporting the HSDPA status in the AUDIT RESPONSE message is the same as the HSDPA status information shown in Tables 2 and 4.  
      However, if the RNC determines that it has different configuration/status information from that of the Node B, it can order the Node B to conduct an audit by transmitting the AUDIT REQUEST message to the Node B, without the need for receiving the AUDIT REQUIRED INDICATION message.  
      1.2. Operations  
      The operations of the Node B and the RNC in accordance with the embodiment of the present invention will be described herein below in more detail.  
      1.2.1 Operation of Node B  
       FIG. 5  is a flowchart illustrating a control operation in a Node B for reporting an HSDPA hardware change to the RNC, when a change occurs in the HSDPA hardware, according to an embodiment of the present invention. Referring to  FIG. 5 , the Node B monitors the status of HSDPA hardware in steps  510 ,  512 , and  514 . If the HSDPA hardware status is changed, the Node B reports the change to the RNC.  
      In step  510 , the Node B determines if an HSDPA hardware device has been added. If a device has been added, the Node B generates an HSDPA cell to which the added HSDPA hardware device is mapped in step  516  and increments a parameter, Max Number of HSDPA Cells by 1 in step  518 . Max Number of HSDPA Cells is defined as the current number of cells available for HSDPA. The Node B notifies the RNC of the changed count of Max Number of HSDPA Cells by a RESOURCE STATUS INDICATION (No failure) message in step  524 .  
      The Node B determines if an HSDPA hardware device has been deleted in step  512 . If the HSDPA hardware device has been deleted, the Node B deletes an HSDPA cell to which the HSDPA hardware device is mapped in step  520  and decrements Max Number of HSDPA Cells by 1 in step  522 . The Node B notifies the RNC of the changed count of Max Number of HSDPA Cells by the RESOURCE STATUS INDICATION (No failure) message in step  524 .  
      The Node B determines if the status of an HSDPA hardware device has been changed in step  514 . If the HSDPA hardware device has been changed, the Node B sets HSDPA Information to a value indicating the changed HSDPA hardware status in step  526  and transmits a RESOURCE STATUS INDICATION (Service Impacting) message containing the value of HSDPA Information to the RNC in step  528 .  
       FIG. 6  is a flowchart illustrating a control operation in the Node B for allocating HSDPA resources as requested by the RNC according to an embodiment of the present invention. Referring to  FIG. 6 , the Node B receives a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message from the RNC in step  610  and determines if the received message indicates the first request of HSDPA resources allocation to Cell x from the RNC in step  612 . If the received message indicates the first request of HSDPA resources allocation to Cell x from the RNC, the Node B determines if there is an HSDPA cell (HSDPA Cell y) that can provide the requested HSDPA resources and has been spared from allocation to other cells in step  618 . If HSDPA Cell y exists, the Node B proceeds to step  620 , but if HSDPA Cell y does not exist, the Node B jumps to step  632 .  
      In step  620 , the Node B maps the HSDPA service of Cell x to HSDPA Cell y and stores the mapping relationship. The Node B allocates the HSDPA resources requested by the RNC in step  624  and notifies the RNC of a successful setup of the requested HSDPA resources by a PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message in step  630 . That is, the Node B notifies the RNC by the PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message that the HSDPA service can be provided through Cell x as the requested HSDPA resources are established in the Node B. However, in step  632 , the Node B transmits, to the RNC, a PHYSICAL SHARED CHANNEL RECONFIGURATION FAILURE message indicating a failed setup of the requested HSDPA resources.  
      After receiving the PHYSICAL SHARED CHANNEL RECONFIGURATION REQUESTE message, the Node B determines if the RNC requests the change of HSDPA resources allocated to Cell x in step  614 . If the RNC requests the change of HSDPA resources allocated to Cell x, the Node B proceeds to step  622 .  
      In step  622 , the Node B determines if the HSDPA Cell y mapped to Cell x can provide the requested HSDPA resources. If the requested HSDPA resources can be provided, this implies that the HSDPA resources of Cell x can be changed. In this case, the Node B allocates the requested HSDPA resources in step  624  and transmits to the RNC the PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message indicating the successful change of the HSDPA resources as requested by the RNC in step  630 . However, if the HSDPA resources cannot be changed in step  622 , the Node B transmits to the RNC the PHYSICAL SHARED CHANNEL RECONFIGURATION FAILURE message indicating the failure of changing the HSDPA resources as requested by the RNC in step  632 .  
      After receiving the PHYSICAL SHARED CHANNEL RECONFIGURATION REQUESTE message, the Node B determines if the RNC requests deletion of HSDPA resources allocated to Cell x in step  616 . If the RNC requests deletion of HSDPA resources allocated to Cell x, the Node B proceeds to step  626 .  
      The Node B deletes the HSDPA resources of Cell x in step  626  and deletes the mapping between Cell x and HSDPA Cell y in step  628 . Therefore, HSDPA Cell y can be mapped to any other cell later. In step  630 , the Node B transmits to the RNC a PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message indicating the successful deletion of the HSDPA resources. That is, the Node B notifies the RNC, using the PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message, that the requested HSDPA resources have been deleted from the Node B to be available later for the HSDPA service through Cell x  
      1.2.2 Operation of RNC  
       FIG. 7  is a flowchart illustrating a control operation after receiving the RESOURCE STATUS INDICATION (No Failure) message from the Node B in the RNC according to an embodiment of the present invention. Referring to  FIG. 7 , upon receiving the RESOURCE STATUS INDICATION (No Failure) message from the Node B in step  710 , the RNC determines if an HSDPA cell has been added by comparing Max Number of HSDPA Cells set in the received message with an existing stored Max Number of HSDPA Cells in step  712 .  
      If an HSDPA cell has been added, the RNC updates the stored Max Number of HSDPA Cells to the new received Max Number of HSDPA Cells in step  716 . That is, the RNC increments the stored Max Number of HSDPA Cells by 1 and stores the incremented Max Number of HSDPA Cells as an updated Max Number of HSDPA Cells. Accordingly, the RNC recognizes that the Node B can additionally provide the HSDPA service. In step  718 , the RNC determines whether to allocate HSDPA resources to Cell x. If the RNC determines to allocate HSDPA resources to Cell x, the RNC performs an HSDPA resource allocation operation in step  720 , which will be described in more detail below with reference to  FIG. 13 .  
      In the absence of an added HSDPA cell in step  712 , the RNC determines if an existing HSDPA cell has been deleted by comparing Max Number of HSDPA Cells set in the received message with the stored Max Number of HSDPA Cells in step  714 .  
      If an HSDPA cell has been deleted, the RNC updates the stored Max Number of HSDPA Cells to the new received Max Number of HSDPA Cells in step  722 . That is, the RNC decrements the stored Max Number of HSDPA Cells by 1 and stores the decremented Max Number of HSDPA Cells as an updated Max Number of HSDPA Cells.  
       FIG. 8  is a flowchart illustrating a control operation after receiving the RESOURCE STATUS INDICATION (Service Impacting) message from the Node B in the RNC according to an embodiment of the present invention. Referring to  FIG. 8 , upon receiving the RESOURCE STATUS INDICATION (Service Impacting) message from the Node B in step  810 , the RNC determines from HSDPA Information set in the received message if HSDPA functionality related to Cell x receiving the HSDPA service has been degraded in step  812 . If the HSDPA functionality has been degraded, the RNC proceeds to step  816 , but if the HSDPA functionality has not been degraded, the RNC proceeds to step  814 . The RNC performs an HSDPA resource reallocation operation to compensate for the HSDPA functionality degradation in step  816 . The HSDPA resource reallocation operation will be described in more detail below with reference to  FIG. 13 .  
      In step  814 , the RNC determines from HSDPA Information set in the received message if HSDPA functionality related to Cell x receiving the HSDPA service is available. If the HSDPA functionality is unavailable, the RNC determines if there are available HSDPA resources in step  818 , by using Equation (1). 
 
(Current number of  HSDPA  cells)−(current number of cells having  HSDPA  logical resources)≧1  (1) 
 
      If Equation (1) is satisfied, which implies that HSDPA resources are available, the RNC performs an HSDPA resource deletion operation by releasing HSDPA resources allocated to Cell x and allocating the available HSDPA resources to Cell x in step  820 . The HSDPA resource switching operation will be described in more detail below with reference to  FIG. 15 .  
      If Equation (1) is not satisfied, which indicates the absence of available HSDPA resources, the RNC deletes the HSDPA resources allocated to Cell x in step  822 . The HSDPA resource deletion will be described in more detail below with reference to  FIG. 4 .  
      Hereinbelow, the HSDPA resource allocation, switching, and deletion operations addressed in  FIGS. 7 and 8  will be described in more detail.  
       FIG. 13  is a flowchart illustrating an HSDPA resource allocation procedure according to an embodiment of the present invention. Referring to  FIG. 13 , the RNC sets a maximum power level for the HS-PDSCH and the HS-SCCH for Cell x, to which the RNC determines to provide the HSDPA service, in step  1300  and determines a scrambling code for the HS-PDSCH and the HS-SCCH in step  1302 . The RNC sets HS-PDSCH FDD code information based on a code allocated to the HS-PDSCH in step  1304  and sets HS-SCCH FDD code information based on a code allocated to the HS-SCCH in step  1306 . In step  1308 , the RNC generates a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message including the above-described HSDPA resource information and transmits it to the Node B.  
       FIG. 14  is a flowchart illustrating an HSDPA resource deletion procedure according to an embodiment of the present invention. Referring to  FIG. 14 , the RNC does not allocate any code in FDD code information of the HS-PDSCH, thereby deleting resources from the HS-PDSCH in step  1400  and does not allocate any code in FDD code information of the HS-SCCH, thereby deleting resources from the HS-SCCH in step  1402 . As a result, HSDPA resources are deleted from the HS-PDSCH and the HS-SCCH. In step  1404 , the RNC generates a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message including the HSDPA resource deletion information and transmits it to the Node B.  
       FIG. 15  is a flowchart illustrating an HSDPA resource switching procedure according to an embodiment of the present invention. Referring to  FIG. 15 , if HSDPA resources allocated to Cell x are invalid and thus the HSDPA service is unavailable to Cell x, the RNC deletes the HSDPA resources from Cell x in step  1500 , as described with reference to  FIG. 14 . If HSDPA resources are available, the RNC reallocates the available HSDPA resources to Cell x in step  1502 , as described with reference to  FIG. 13 .  
     2. Second Embodiment  
      2.1.1 Signaling at Initialization for HSDPA Service  
      When a local cell is added as HSDPA hardware is initialized, the Node B notifies the CRNC as to whether each local cell supports HSDPA functionality by a RESOURCE STATUS INDICATION (No Failure) message.  
      Referring to  FIG. 1 , upon sensing the initialization of the HSDPA hardware, the Node B transmits the RESOURCE STATUS INDICATION (No Failure) message to the CRNC to notify if the HSDPA functionality is supported in each local cell in step  110 .  
      Table 5 below specifies the structure of the RESOURCE STATUS INDICATION message.  
                       TABLE 5                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       CHOICE Indication Type   M       &gt;No Failure       &gt;&gt;Local Cell       1 . . . &lt;max       Information       LocalCellinNodeB&gt;       &gt;&gt;&gt;Local Cell ID   M       . . . (omitted)       &gt;&gt;&gt;HSDPA Support   M       Indicator       &gt;&gt;&gt;HSDPA information   C-HSDPASupport       &gt;&gt;&gt;&gt;MAC-hs Buffer   M       Credit       &gt;&gt;&gt;&gt;Maximum   M       HS-PDSCH Code       &gt;&gt;&gt;&gt;Maximum DL   M       Power Capability       . . . (omitted)                  
 
      In Table 5, HSDPA Support Indicator indicates if a corresponding local cell supports HSDPA functionality. For example, if the local cell supports the HSDPA functionality, HSDPA Support Indicator is set to Support. If the local cell does not support the HSDPA functionality, HSDPA Support Indicator is set to Not Support. In the former case, the RESOURCE STATUS INDICATION message must include HSDPA Information.  
      The following parameters are included in HSDPA Information.  
      MAC-hs Buffer Credit: A parameter indicating the maximum capacity of the HSDPA functionality of the local cell. It is the size of a MAC_hs buffer.  
      Maximum HS-PDSCH Code: The number of HS-PDSCH codes that can be processed in the local cell.  
      Maximum DL Power Capability: The maximum power available for the HSDPA service in the local cell.  
      The RNC performs a setup procedure based on the local cell information received by the RESOURCE STATUS INDICATION message. In the setup procedure, the RNC sets up cells for the Node B and then allocates HSDPA resources to cells that will provide the HSDPA service. In step  120 , the RNC transmits a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message containing HSDPA resource allocation information to the Node B. The cells that will provide the HSDPA service must be cells to which local cells supporting HSDPA are mapped. If HSDPA resources are allocated to a cell to which a non-HSDPA local cell is mapped by the PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message, the Node B rejects the HSDPA resource allocation by transmitting a PHYSICAL SHARED CHANNEL RECONFIGURATION FAILURE message (not shown in  FIG. 1 ).  
      While the procedure is performed for individual local cells in the above description, it can be further contemplated that the procedure can also be performed for local cell groups. In this case, the Node B notifies the RNC as to whether each local cell group supports HSDPA. Accordingly, the above-described HSDPA Information is included for each HSDPA-supporting local cell group. A RESOURCE STATUS INDICATION message used to indicate if local cell groups support HSDPA is configured as follows.  
                       TABLE 6                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       CHOICE Indication Type   M       &gt;No Failure       &gt;&gt;Local Cell Group       1 . . . &lt;max       Information       LocalCellGroupinNodeB&gt;       &gt;&gt;&gt;Local Group Cell ID   M       . . . (omitted)       &gt;&gt;&gt;HSDPA information       0 . . . 1       &gt;&gt;&gt;&gt;MAC-hs Buffer   M       Credit       &gt;&gt;&gt;&gt;Maximum   M       HS-PDSCH code       &gt;&gt;&gt;&gt;Maximum DL Power   M       Capability       . . . (omitted)                  
 
      In Table 6, HSDPA Information includes the same parameters as described with reference to Table 5.  
      After setting up HSDPA resources allocated by the PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message in step  130 , the Node B transmits a PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message to the RNC in step  140 .  
      2.1.2 Signaling in the Case of Change in HSDPA Service Capability  
      When the initially reported HSDPA capability of a local cell is changed or the HSDPA capability of a cell to which HSDPA were allocated, the Node B reports the HSDPA capability change to the RNC by a RESOURCE STATUS INDICATION (Service Impacting) message.  
      Table 7 below illustrates a structure of the RESOURCE STATUS INDICATION (Service Impacting) message.  
                       TABLE 7                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       CHOICE Indication Type   M       &gt;Service Impacting       &gt;&gt;Local Cell Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;&gt;HSDPA Support Indicator   M       &gt;&gt;&gt;HSDPA information       C-HSDPASupport       &gt;&gt;&gt;&gt;MAC-hs Buffer Credit   M       &gt;&gt;&gt;&gt;Maximum HS-PDSCH code   M       &gt;&gt;&gt;&gt;Maximum DL Power Capability   M       &gt;&gt;Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;&gt;HSDPA information       0 . . . 1       &gt;&gt;&gt;&gt;MAC-hs Buffer Credit   M       &gt;&gt;&gt;&gt;Maximum HS-PDSCH code   M       &gt;&gt;&gt;&gt;Maximum DL Power Capability   M       &gt;&gt;Power Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Communication Control Port Information       0 . . . &lt;maxCCPinNodeB&gt;       . . . (omitted)       &gt;&gt;Cell Information       0 . . . &lt;maxCellinNodeB&gt;       &gt;&gt;&gt;C-ID   M       &gt;&gt;&gt;Resource Operational State   O       &gt;&gt;&gt;Availability Status   O       &gt;&gt;&gt;HSDPA Status Information       0 . . . 1       &gt;&gt;&gt;&gt;Resource Operational State   M       &gt;&gt;&gt;&gt;Availability Status   M                  
 
      In Table 7, HSDPA Information is the same as HSDPA Information of Table 4 and HSDPA Status Information is the same as that illustrated in Table 3.  
      If a change occurs in the HSDPA capability of Local Cell y while Cell x is providing the HSDPA service through Local Cell y, Cell x cannot provide the HSDPA service successfully any more. Therefore, the RNC deletes HSDPA resources from Cell x by a Physical Shared Channel Reconfiguration procedure. Also, the RNC deletes radio links from UEs that receive the HSDPA service from Local Cell y.  
      2.1.3 Signaling Procedure for Different Configuration Information Between Node B and RNC  
      If the RNC or the Node B determines that configuration/status information differs in them, an audit operation is performed. When determining that the configuration/status information of the RNC is different from that of the Node B, the Node B tells the RNC that an audit is required by an AUDIT REQUIRED INDICATION message. The RNC then orders the Node B to conduct the audit by an AUDIT REQUEST message. In accordance with the second embodiment of the present invention, upon receiving the AUDIT REQUEST message, the Node B transmits the following HSDPA information by an AUDIT RESPONSE message. 
          1) Local Cell Information 
            &gt;HSDPA Support Indicator     &gt;HSDPA Information 
                &gt;&gt;MAC-hs Buffer Credit     &gt;&gt;Maximum HS-PDSCH Code     &gt;&gt;Maximum DL Power Capability    
               
            2) Cell Information 
            &gt;HSDPA Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
                &gt;HS-PDSCH Status Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
                &gt;HS-SCCH Status Information 
                &gt;Resource Operational State     &gt;&gt;Availability Status    
               
               

      Information included for reporting the HSDPA status in the AUDIT RESPONSE message is the same as the HSDPA status information shown in Tables 5 and 7.  
      However, if the RNC determines that it has different configuration/status information from that of the Node B, it can order the Node B to conduct an audit by transmitting the AUDIT REQUEST message to the Node B, without the need for receiving the AUDIT REQUIRED INDICATION message.  
      2.2. Operations  
      The operations of the Node B and the RNC in accordance with the 15 second embodiment of the present invention will be described in more detail herein below.  
      2.2.1 Operation of Node B  
       FIG. 9  is a flowchart illustrating a control operation in a Node B for reporting an HSDPA hardware change to the RNC, when a change occurs in the HSDPA hardware, according to a second embodiment of the present invention. Referring to  FIG. 9 , the Node B determines if a local cell has been added in step  910 . If the local cell has been added, the Node B determines if the local cell supports HSDPA functionality in step  918 . If the local cell does not support HSDPA functionality, the Node B sets HSDPA Support Indicator to Not Support in step  920  and proceeds to step  926 . If the local cell does support the HSDPA functionality, the Node B sets HSDPA Support Indicator to Support in step  922 , sets HSDPA information about the local cell in HSDPA Information in step  924 , and proceeds to step  926 .  
      The structure of HSDPA Information is shown in Table 5.  
      The Node B sets local cell information and HSDPA resource information about the local cell and transmits it to the RNC by a RESOURCE STATUS INDICATION (No Failure) message in step  926 .  
      In the absence of a local cell to be added, the Node B determines if an HSDPA hardware device has been added to a local cell in step  912 . If the HSDPA hardware device has been added, the Node B sets HSDPA Support Indicator to Support in step  928  and sets HSDPA information about the local cell in HSDPA Information in step  930 . The Node B sets HSDPA resource change information about the local cell and transmits it to the RNC by a RESOURCE STATUS INDICATION (No Failure) message in step  932 .  
      In step  914 , the Node B determines if an HSDPA hardware status in a local cell has been changed. If the HSDPA hardware status has been changed, the Node B sets HSDPA Support Indicator to Not Support in step  934  and proceeds to step  932 .  
      In step  916 , the Node B determines if an HSDPA hardware device has been deleted in a local cell. If the HSDPA hardware device has been deleted, the Node B sets HSDPA Support Indicator to Not Support in step  934  and proceeds to step  932 .  
       FIG. 10  is a flowchart illustrating a control operation in the Node B for allocating HSDPA resources as requested by the RNC according to the second embodiment of the present invention. Referring to  FIG. 10 , the Node B receives a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message from the RNC in step  1010  and determines if the received message requests allocation of HSDPA resources to Cell x in step  1012 . If the received message requests allocation of HSDPA resources to Cell x, the Node B determines if the requested HSDPA resources are available in step  1016 . If HSDPA resources are available in a local cell to which Cell x has been mapped, the Node B proceeds to step  1020 . If the HSDPA resources are not available in the local cell, the Node B proceeds to step  1018 .  
      The Node B allocates the HSDPA resources requested by the RNC in step  1020  and notifies the RNC of a successful setup of the requested HSDPA resources by a PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message in step  1022 . However, in step  1018 , the Node B transmits to the RNC a PHYSICAL SHARED CHANNEL RECONFIGURATION FAILURE message indicating a failed setup of the requested HSDPA resources.  
      After receiving the PHYSICAL SHARED CHANNEL RECONFIGURATION REQUESTE message, the Node B determines if the RNC requests deletion of HSDPA resources allocated to Cell x in step  1014 . If the RNC requests deletion of HSDPA resources allocated to Cell x, the Node B deletes the HSDPA resources of Cell x in step  1024  and transmits to the RNC a PHYSICAL SHARED CHANNEL RECONFIGURATION RESPONSE message indicating the successful deletion of the HSDPA resources in step  1022 .  
      2.2.2 Operation of RNC  
       FIG. 11  is a flowchart illustrating a control operation after receiving the RESOURCE STATUS INDICATION (No Failure) message from the Node B in the RNC according to the second embodiment of the present invention. Referring to  FIG. 11 , upon receiving the RESOURCE STATUS INDICATION (No Failure) message from the Node B in step  1110 , the RNC determines if a local cell has been added in step  1112 . If a local cell has been added, the RNC determines if the local cell supports HSDPA functionality in step  1114 . If the local cell supports HSDPA functionality, the RNC determines if the HSDPA service can be provided through Cell x to which the local cell has been mapped in step  1116 . That is, the RNC determines whether to allocate HSDPA resources by determining HSDPA service availability through Cell x. If the HSDPA resources can be allocated, the RNC performs the HSDPA resource allocation procedure illustrated in  FIG. 13  in step  1118 .  
      In accordance with the second embodiment of the present invention, when Cell x did not support HSDPA service, new HSDPA resources are allocated to Cell x.  
       FIG. 12  is a flowchart illustrating a control operation after receiving the RESOURCE STATUS INDICATION (Service Impacting) message from the Node B in the RNC according to the second embodiment of the present invention. Referring to  FIG. 12 , receiving the RESOURCE STATUS INDICATION (Service Impacting) message from the Node B in step  1210 , the RNC determines from HSDPA Status Information set in the received message if HSDPA functionality related to Cell x receiving the HSDPA service has been degraded in step  1212 . If the HSDPA functionality has been degraded, the RNC proceeds to step  1216 , but otherwise, it proceeds to step  1214 . In step  1216 , the RNC performs an HSDPA resource reallocation operation to compensate for the HSDPA functionality degradation in the procedure illustrated in  FIG. 13 .  
      In step  1214 , the RNC determines from HSDPA Information set in the received message if HSDPA functionality related to Cell x receiving the HSDPA service is available. If the HSDPA functionality is unavailable, the RNC deletes HSDPA resources allocated to Cell x in the procedure illustrated in  FIG. 14 .  
     3. Third Embodiment  
      A third embodiment of the present invention provides a method of reporting a change in the HSDPA capability of a Node B to an RNC by the Node B when the HSDPA capability has been changed due to a change in HSDPA hardware. A new concept, i.e., HSDPA cell, is introduced here.  
       FIG. 3  illustrates a Node B to which the concept of HDPA cell is applied. Referring to  FIG. 3 , the Node B includes a plurality of local cell groups  321  and  322  and an HSDPA cell group  341 . The local cell groups  321  and  322  each include a plurality of local cells. The first local cell group  321  has first, second, and third local cells  311 ,  312 , and  313 , and the second local cell group  322  includes fourth and fifth local cells  314  and  315 . The HSDPA cell group  341  includes a plurality of HSDPA cells  331 ,  332 , and  333 . Sixth and seventh local cells belong to none of the local cell groups. A fourth HSDPA cell  324  belongs to none of HSDPA cell groups. An HSDPA cell manages and controls HSDPA functionality, and resources such as HS-PDSCH, HS-SCCH, and MAC-hs.  
      3.1 Signaling  
      3.1.1 Signaling at Initialization for HSDPA Service  
      When an HSDPA cell is added as HSDPA hardware is initialized, or when the HSDPA functionality is partially or wholly removed, and thus an HSDPA cell is removed due to removal of an HSDPA hardware device, the Node B reports the situation to the RNC by a RESOURCE STATUS INDICATION (No Failure) message.  
      Referring to  FIG. 1 , at an initialization for HSDPA, the Node B  10  transmits its HSDPA cell information to the CRNC  20  by a RESOURCE STATUS INDICATION (No Failure) message in step  110 . However, when addition or removal of an HSDPA hardware device results in addition or removal of an HSDPA cell in the Node B  10 , the Node B  10  reports this situation to the CRNC  20  by the RESOURCE STATUS INDICATION (No Failure) message in step  110 . That is, the Node B  10  reports information about local cells/local cell groups and HSDPA cell information to the CRNC  20  by the RESOURCE STATUS INDICATION (No Failure) message.  
      The RNC maps local cells to Cells by a Call Setup procedure and maps HSDPA cells to Cells by a Physical Shared Channel Reconfiguration procedure.  
       FIG. 4  illustrates Cells constructed by a Cell Setup/Common Transport Channel Setup/Physical Shared Channel Reconfiguration procedure. Referring to  FIG. 4 , a second cell  452  (Cell  2 ) includes a second local cell  412  (Local Cell  2 ) and a first HSDPA cell  431  (HSDPA Cell  1 ). The RNC can add HSDPA functionality to a cell based on the HSDPA cell information by the Physical Shared Channel Reconfiguration procedure.  
      Table 8 below shows the structure of a RESOURCE STATUS INDICATION message that the Node B transmits to the RNC upon initialization for HSDPA according to the third embodiment of the present invention.  
                       TABLE 8                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       CHOICE Indication Type   M       &gt;No Failure       &gt;&gt;Local Cell Information       1 . . . &lt;max LocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       ... (omitted)       &gt;&gt;Power Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt; HSDPA Cell Information       0 . . . &lt;maxHSDPACellinNodeB&gt;       &gt;&gt;&gt;HSDPA Cell ID   M       &gt;&gt;&gt;Add/Delete Indicator   M       &gt;&gt;&gt; HSDPA Cell Group ID   O       &gt;&gt;&gt;MAC-hs Buffer Credit   C-add       &gt;&gt;&gt;Maximum HS-PDSCH code   C-add       &gt;&gt;&gt;Maximum DL Power Capability   C-add       &gt;&gt;&gt; ???                  
 
      In Table 8, HSDPA Cell Information includes the following parameters.  
      HSDPA Cell ID: An ID that identifies an HSDPA cell in the Node B.  
      Add/Delete Indicator: If Add, it indicates addition of an HSDPA cell. If Delete, it indicates deletion of an HSDPA cell.  
      HSDPA Cell Group ID: An ID that identifies an HSDPA cell group to which an HSDPA cell belongs.  
      MAC-hs Buffer Credit: A parameter indicating the maximum capacity of the HSDPA functionality for the HSDPA cell. It is a Mac-hs buffer size and included when Add/Delete Indicator is set to Add.  
      Maximum HS-PDSCH Code: The maximum number of HS-PDSCH codes that can be processed in the HSDPA cell.  
      Maximum DL Power Capability: The maximum power supported by the HSDPA cell. It is included if Add/Delete Indicator is set to Add.  
      Along with the definition of HSDPA cell, a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message is modified as follows.  
                       TABLE 9                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       C-ID   M       SFN   O       HSDPA Cell ID   O       HS-PDSCH and HS-SCCH Total Power   O       HS-PDSCH and HS-SCCH Scrambling Code   O       HS-PDSCH FDD Code Information       0 . . . 1       HS-SCCH FDD Code Information       0 . . . 1                  
 
      In Table 9, HSDPA Cell ID is added to the message to thereby define the mapping relationship between C-ID and HSDPA Cell ID.  
      3.1.2 Signaling in the Case of Change in HSDPA Service Capability  
      When the initially reported HSDPA capability of an HSDPA cell is changed or the HSDPA capability of a cell to which HSDPA resources were allocated, the Node B reports the HSDPA capability change to the RNC by a RESOURCE STATUS INDICATION (Service Impacting) message.  
      Table 10 below illustrates the structure of the RESOURCE STATUS INDICATION (Service Impacting) message.  
                       TABLE 10                       IE/Group Name   Presence   Range                  Message Discriminator   M           Message Type   M       Transaction ID   M       CHOICE Indication Type   M       &gt;Service Impacting       &gt;&gt;Local Cell Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Power Local Cell Group Information       0 . . . &lt;maxLocalCellinNodeB&gt;       . . . (omitted)       &gt;&gt;Communication Control Port Information       0 . . . &lt;maxCCPinNodeB&gt;       . . . (omitted)       &gt;&gt;Cell Information       0 . . . &lt;maxCellinNodeB&gt;       &gt;&gt;&gt;C-ID   M       &gt;&gt;&gt;Resource Operational State   O       &gt;&gt;&gt;Availability Status   O       . . . (omitted)       &gt;&gt;&gt;HS-PDSCH Status Information       0 . . . 1       &gt;&gt;&gt;&gt;Resource Operational State   M       &gt;&gt;&gt;&gt;Availability Status   M       &gt;&gt;&gt;HS-SCCH Status Information       0 . . . 1       &gt;&gt;&gt;&gt;Resource Operational State   M       &gt;&gt;&gt;&gt;Availability Status   M       &gt;&gt; HSDPA Cell Information       0 . . . &lt;maxHSDPACellinNodeB&gt;       &gt;&gt;&gt;HSDPA Cell ID   M       &gt;&gt;&gt;MAC-hs Buffer Credit   O       &gt;&gt;&gt;Maximum HS-PDSCH code   O       &gt;&gt;&gt;Maximum DL Power Capability   O       &gt;&gt;&gt; ???                  
 
      In Table 10, HSDPA Cell Information is the same as HSDPA Cell Information of Table 8. Cell Information includes HS-PDSCH Status Information and HS-SCCH Status Information to report HSDPA service capability. The HSDPA Cell Information may include HSDPA Information as shown in Table 6.  
      If MAC-hs Buffer Credit, Maximum HS-PDSCH code, or Maximum DL Power Capability in HSDPA Cell Information is changed, the RNC can re-set up HSDPA resources to the Node B according to the changed capability by the Physical Shared Channel Reconfiguration procedure.  
      If a change occurs in the capability of HSDPA Cell y while Cell x is providing the HSDPA service through HSDPA Cell y, Cell x cannot provide the HSDPA service successfully any more and attempts a resource switching in the following manner. If the maximum number of HSDPA cells is greater than the current number of cells to which the HSDPA service is allocated, the RNC allocates an unused HSDPA cell, HSDPA Cell z to Cell x by the Physical Shared Channel Reconfiguration procedure. The PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message includes the ID of HSDPA Cell z. Also, the RNC re-establishes an HSDPA RL for a UE receiving the HSDPA service through Cell x to thereby continue the HSDPA service through Cell x. The RNC then notifies the UE of a change such as changed HS-PDSCH (High Speed-Physical Downlink Shared CHannel) or HS-SCCH (High Speed-Shared Control CHannel) code information (MAC-hs reset needed) by an RRC message, if the change occurs.  
      3.1.3 Signaling Procedure for Different Configuration Information between Node B and RNC  
      If the RNC or the Node B determines that configuration/status information differs between them, an audit operation is performed. When determining that the configuration/status information of the RNC is different from that of the Node B, the Node B notifies the RNC that an audit is required by an AUDIT REQUIRED INDICATION message. The RNC then orders the Node B to conduct the audit by an AUDIT REQUEST message. In accordance with the third embodiment of the present invention, upon receiving the AUDIT REQUEST message, the Node B transmits the following HSDPA information to the RNC by an AUDIT RESPONSE message. 
          1) HSDP Cell Information 
            &gt;HSDPA Cell ID     &gt;MAC-hs Buffer Credit     &gt;Maximum HS-PDSCH Code     &gt;Maximum DL Power Capability    
            2) Cell Information 
            &gt;HSDPA Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
                &gt;HS-PDSCH Status Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
                &gt;HS-SCCH Status Information 
                &gt;&gt;Resource Operational State     &gt;&gt;Availability Status    
               
               

      Information included for reporting the HSDPA status in the AUDIT RESPONSE message is the same as the HSDPA status information illustrated in Table 10.  
      However, if the RNC determines that it has different configuration/status information from that of the Node B, it can order the Node B to conduct an audit by transmitting the AUDIT REQUEST message to the Node B, without the need for receiving the AUDIT REQUIRED INDICATION message.  
      HSDPA resource allocation and switching will be described below with reference to  FIGS. 16 and 17 .  
       FIG. 16  is a flowchart illustrating an HSDPA resource allocation procedure according to the third embodiment of the present invention. Referring to  FIG. 16 , the RNC determines HSDPA Cell y for Cell x based on HSDPA Cell Information set in a RESOURCE STATUS INDICATION message received from the Node B in step  1610  and sets a maximum power level for the HS-PDSCH and the HS-SCCH for Cell x to which the RNC determines to provide the HSDPA service in step  1612 . The RNC determines a scrambling code for the HS-PDSCH and the HS-SCCH in step  1614 . The RNC sets FDD code information based on a code allocated to the HS-PDSCH in step  1616  and sets FDD code information based on a code allocated to the HS-SCCH in step  1618 . In step  1620 , the RNC generates a PHYSICAL SHARED CHANNEL RECONFIGURATION REQUEST message containing the above HSDPA resource information and transmits it to the Node B.  
       FIG. 17  is a flowchart illustrating an HSDPA resource switching procedure according to the third embodiment of the present invention. Referring to  FIG. 17 , if HSDPA resources allocated to Cell x are invalid and thus the HSDPA service is unavailable to Cell x, the RNC deletes the HSDPA resources from Cell x in step  1810 , as described with reference to  FIG. 14 . If there is HSDPA Cell z that is not mapped to any cell in the Node B, the RNC reallocates HSDPA Cell z to Cell x in the procedure described in  FIG. 16 , in step  1712 .  
      In accordance with the present invention, as described above, an RNC manages the status of resources allocated for HSDPA service, thereby efficiently allocating resources in an HSDPA mobile communication system. Furthermore, resource switching is fast even when the HSDPA service is unavailable using the allocated resources. Therefore, the HSDPA service is stably provided.  
      While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.