Abstract:
In an asynchronous CDMA mobile communication system supporting HSDPA (High Speed Downlink Packet Access), in order to assign power to a high speed physical downlink shared channel (HS-PDSCH), a power offset is determined and then provided to a Node B and a user equipment (UE). For this, an HS-PDSCH power offset is determined by a controlling radio network controller (CRNC) and a Node B, and then transmitted to the UE or the Node B.

Description:
PRIORITY 
   This application claims priority under 35 U.S.C. § 119 to an application entitled “Method for Determining Power Offset of HS-PDSCH in an Asynchronous CDMA Mobile Communication System and Signaling Method Therefor” filed in the Korean Intellectual Property Office on May 11, 2002 and assigned Serial No. 2002-26055, the contents of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a downlink packet communication method in a code division multiple access (hereinafter referred to as “CDMA”) mobile communication system employing high speed downlink packet access (hereinafter referred to as “HSDPA”), and in particular, to a method for assigning power of a high speed physical downlink shared channel (hereinafter referred to as “HS-PDSCH”). 
   2. Description of the Related Art 
   The mobile communication system has evolved from an early circuit-based mobile communication system, chiefly supporting a voice service, into a high-speed, high-quality packet-based mobile communication system supporting a data service and a multimedia service. A 3 rd  generation mobile communication system is divided into an asynchronous 3GPP (3 rd  Generation Partnership Project) system and a synchronous 3GPP2 (3 rd  Generation Partnership Project 2) system, and standardization for the 3 rd  generation mobile communication system is currently being conducted for a high-speed, high-quality radio packet data service. For example, standardization for HSDPA is being conducted in 3GPP, while standardization for 1×EV-DV (Evolution-Data and Voice) is being carried out in 3GPP2. The standardization is being performed to find a solution for providing a high-speed, high-quality radio packet data service of 2 Mbps or higher in a 3 rd  generation mobile communication system. A 4 th  generation mobile communication system is attempting to provide a high-speed, high-quality multimedia service of a much higher data rate. 
     FIG. 1  schematically illustrates a cell provided in an asynchronous CDMA mobile communication system. Referring to  FIG. 1 , a Node B  101  communicates with user equipments (UEs)  104 ,  106 , and  108  over downlink and uplink channels set up therebetween. Downlink physical channels used in HSDPA are divided into a dedicated physical channel, which is exclusively used by one UE and common channels, such as a common pilot channel (CPICH), a primary common control channel (P-CCCH), a secondary common control channel (S-CCCH), a high speed physical downlink shared channel (HS-PDSCH), and a high speed shared control channel (HS-SCCH). 
   The Node B  101  transmits the above-stated downlink physical channels. In  FIG. 1 , reference numerals  103 ,  105 ,  107 , and  109  represent the downlink physical channels with arrows according to their types. Of the reference numerals, reference numeral  103  represents common channels, such as a common pilot channel, a primary common control channel, a secondary common control channel, and other indication channels. The Node B  101  assigns power so that signals on the common channels can arrive at up to a boundary of the cell, and then transmits the common channel signals to the UEs  104 ,  106 , and  108  at the assigned power. This is because all UEs exiting in the cell should be able to receive the common channels. The common channels to which power was assigned the by the Node B is scarcely changed with the passage of time. 
   Reference numerals  105  and  107  represent dedicated physical channels among the downlink physical channels. An arrow shown by the reference numeral  105  represents a dedicated physical channel for communication with the UE  104 , while an arrow shown by reference numeral  107  represents a dedicated physical channel for communication with the UE  106 . The dedicated physical channel is assigned optimum power so that only the UE in communication can receive the dedicated physical channel. Therefore, as illustrated in  FIG. 1 , the UE  106  located at a relatively farther distance from the Node B  101  as compared with the UE  104  should be assigned higher power for its dedicated physical channel. The dedicated physical channels continuously undergo power control. As the dedicated physical channels are simply created or released, transmission power assigned to the dedicated physical channels are changed with the passage of time. 
   The UE  108  represents a UE receiving an HSDPA service. In  FIG. 1 , reference numeral  109  denotes a high speed physical downlink shared channel or a high speed shared control channel. The UE  108  receives the high speed physical downlink shared channel or high speed shared control channel  109 . Even in the high speed physical downlink shared channel, as the number of UEs or a required service may undergo a change with the passage of time, transmission power assigned thereto is changed. 
   For these reasons, Node B  101  assigns the total power for a dedicated physical channel and HSDPA within the range of remaining power minus the power assigned to the common channel from the total available transmission power. The assigned total HSDPA power is determined by a controlling RNC (Radio Network Controller, hereinafter referred to as “CRNC”) according to circumstances. The CRNC changes the total HSDPA power according to a change in conditions. The CRNC can inform a Node B of the time-varying total HSDPA power through a Physical Shared Channel Reconfiguration Request message, i.e., an NBAP (Node B Application Part) message. The NBAP message represents the total HSDPA power with an information element (hereinafter referred to as “IE”) called “HS-PDSCH and HS-SCCH Total Power.” 
     FIG. 2  is a graph illustrating a time-varying ratio of a total transmission power used by the Node B  101 . In  FIG. 2 , a horizontal axis shown by reference numeral  201  indicates a change in time, and a vertical axis shown by reference numeral  202  indicates power assigned to channels in a Node B. A value shown by reference numeral  207  indicates the total transmission power available for the Node B. Reference numeral  203  indicates power assigned to a common pilot channel, and reference numeral  204  indicates power assigned to other common channels such as a primary common control channel and a secondary common control channel. Commonly, the power  203  and the power  204  are scarcely changed with the passage of time. However, a power assignment ratio for the common channels shown by the reference numerals  203  and  204  can undergo a change according to a characteristic of a cell. That is, a ratio of power  203  and  204  assigned to the common channel to the total Node B power  207  can be changed according to a radius of the cell or a geographical environment. 
   However, Node B power minus the power assigned to the common channel must be assigned for a dedicated physical channel and an HSDPA service. In  FIG. 2 , reference numeral  205  denotes power assigned to a dedicated physical channel, while reference numeral  206  indicates power assigned for an HSDPA service. The power  205  assigned to the dedicated physical channel is non-periodically changed according to a condition of the Node B, as shown by reference numerals  210 ,  211 , and  212 . 
     FIGS. 3 and 4  illustrate structures of an uplink channel and a downlink channel used for an HSDPA service, respectively. Specifically,  FIG. 3  illustrates a structure of a high speed dedicated physical control channel (hereinafter referred to as “HS-DPCCH”), i.e., an uplink channel used for an HSDPA service. 
   Referring to  FIG. 3 , an HS-DPCCH includes a plurality of subframes  301 . Assuming that one radio frame  302  with a length of 10 ms is comprised of 5 subframes, each subframe has a length of 2 ms. One subframe is comprised of 3 time slots. Of the 3 time slots, a first time slot  303  is assigned for transmission of an ACK/NAK signal for HARQ (Hybrid Automatic Repeat reQuest), and the other 2 time slots  304  are assigned for a channel quality indicator (hereinafter referred to as “CQI”). 
   The CQI is determined by a UE, and used to indicate quality of the HS-PDSCH. The UE measures a signal-to-interference ratio (hereinafter referred to as “SIR”) of a CPICH, and determines the CQI by estimating an SIR of the HS-PDSCH depending on a ratio of reception power of the CPICH to reception power of the HS-PDSCH. Therefore, the UE must previously have information on the SIR of the CPICH and a ratio of reception power of the CPICH to reception power of the HS-PDSCH, in order to determine the CQI. The SIR of the CPICH can be measured in the UE. The ratio of reception power of the CPICH to reception power of the HS-PDSCH is identical to a ratio of transmission power of the CPICH to transmission power of the HS-PDSCH. Herein, the ratio of reception power of the CPICH to reception power of the HS-PDSCH or the ratio of transmission power of the CPICH to transmission power of the HS-PDSCH will be referred to as an “HS-PDSCH power offset.” For convenience, the term “CPICH power” used herein indicates either transmission power of CPICH or reception power of CPICH, and the term “HS-PDSCH power” indicates either transmission power of HS-PDSCH or reception power of HS-PDSCH. However, it should be noted that when the CPICH power is construed as transmission power of the CPICH, the HS-PDSCH power should also be interpreted as transmission power of HS-PDSCH. The CPICH power has a different value according to a characteristic of a cell. In addition, as shown by reference numeral  206  of  FIG. 2 , power assigned for HSDPA is also changed with the passage of time. Therefore, the HS-PDSCH power offset is also not a fixed value, but a value changeable according to the type of a cell, timing condition, and power of a common channel. 
     FIG. 4  illustrates a structure of a downlink channel used for an HSDPA service. In  FIG. 4 , reference numeral  410  represents a structure of HS-SCCH, and reference numeral  420  represents a structure of HS-PDSCH. In the HS-SCCH  410  and the HS-PDSCH  420 , a subframe has a length of 2 ms, and is comprised of 3 time slots. In the HS-PDSCH, transmission of a subframe is started at a time when transmission of a third time slot in the HS-SCCH is started. 
   As described in conjunction with  FIGS. 3 and 4 , a UE transmits CQI measured by a CPICH to a Node B over an HS-PDSCH. At this moment, as the CQI is determined by the CPICH, CQI and HS-PDSCH power offset to be applied to HS-PDSCH may be generated. In order to solve this problem, it is necessary to newly define a correct CQI by reflecting an HS-PDSCH power offset in the CQI determined by the CPICH. In addition, the Node B and the UE must previously have information on the HS-PDSCH power offset. 
   Therefore, it is necessary to newly define a scheme for determining the HS-PDSCH power offset and signal processing procedures for sharing the HS-PDSCH power offset in a mobile communication system. 
   SUMMARY OF THE INVENTION 
   It is, therefore, an object of the present invention to provide a method for accurately determining power assigned to a high speed physical downlink shared channel in a Node B and a UE, in order to increase performance of a mobile communication system. 
   It is another object of the present invention to provide a method for determining power assigned to each of high speed physical downlink shared channels in a mobile communication system. 
   It is further another object of the present invention to provide a method for determining a power offset assigned to each of high speed physical downlink shared channels in a mobile communication system. 
   It is yet another object of the present invention to provide a method for signaling a power offset of a high speed physical downlink shared channel between a Node B, an RNC, and a UE. 
   It is still another object of the present invention to provide a method for compensating channel quality measured by a common pilot channel based on a power offset, and using the compensated power offset as a channel quality indicator for a high speed physical downlink shared channel. 
   It is still another object of the present invention to provide a method for determining by a DRNC (Drift RNC) a power offset considering a difference between transmission power of a common pilot channel and transmission power of a high speed physical downlink shared channel. 
   It is still another object of the present invention to provide a method for determining by a Node B a power offset considering a difference between transmission power of a common pilot channel and transmission power of a high speed physical downlink shared channel. 
   It is still another object of the present invention to provide a signaling method for transmitting a power offset determined by a DRNC to a Node B and a UE. 
   It is still another object of the present invention to provide a signaling method for transmitting a power offset determined by a Node B to a UE. 
   In accordance with a first aspect of the present invention, there is provided a method for transmitting predetermined power offset information on a high speed physical downlink shared channel in a drift radio network controller (DRNC) to achieve excellent channel performance indication between a user equipment (UE) existing within a cell and a Node B, in a system including the Node B, the DRNC connected to the Node B, for managing resource information for communication with UEs existing within the cell occupied by the Node B, and a serving radio network controller (SRNC) connected to the DRNC, for transmitting a control message to the UEs. The method comprises sending a radio link setup request from the SRNC to the DRNC, transmitting a radio link setup request message with the power offset information from the DRNC to the Node B; transmitting a radio link setup response message with the power offset information from the DRNC to the SRNC; and transmitting the power offset information from the SRNC to the UE. 
   In accordance with a second aspect of the present invention, there is provided a method for transmitting predetermined power offset information on a high speed physical downlink shared channel in a drift radio network controller (DRNC) to achieve excellent channel performance indication between a user equipment (UE) existing in a cell and a Node B, in a system including the Node B, the DRNC connected to the Node B, for managing resource information for communication with UEs existing within the cell occupied by the Node B, and a serving radio network controller (SRNC) connected to the DRNC, for transmitting a control message to the UEs. The method comprises sending a radio link reconfiguration prepare request from the SRNC to the DRNC; transmitting a radio link reconfiguration prepare message with the power offset information, from the DRNC to the Node B; transmitting a radio link reconfiguration ready message with the power offset information, from the DRNC to the SRNC; and transmitting a radio bearer reconfiguration request message with the power offset information, from the SRNC to the UE. 
   In accordance with a third aspect of the present invention, there is provided a method for transmitting power offset information on a high speed physical downlink shared channel in a Node B to achieve excellent channel performance indication between a user equipment (UE) existing in a cell and the Node B, in a system including the Node B, a drift radio network controller (DRNC) connected to the Node B, for managing resource information for communication with UEs existing within the cell occupied by the Node B, and a serving radio network controller (SRNC) connected to the DRNC, for transmitting a control message to the UEs. The method comprises sending a radio link setup request from the SRNC to the DRNC; transmitting a physical shared channel reconfiguration request message with the total power assigned for an HSDPA (High Speed Downlink Packet Access) service, from the DRNC to the Node B; transmitting a response message for the physical shared channel reconfiguration request message, from the Node B to the DRNC; transmitting a radio link setup request message with HSDPA service-related information, from the DRNC to the Node B; determining, by the Node B, the power offset information considering the total power assigned for the HSDPA service, and transmitting a response message with the power offset information to the DRNC in response to the radio link setup request message; transmitting a radio link setup response message with the power offset information, from the DRNC to the SRNC; and transmitting the power offset information from the SRNC to the UE. 
   In accordance with a fourth aspect of the present invention, there is provided a method for transmitting power offset information on a high speed physical downlink shared channel in a Node B to achieve excellent channel performance indication between a user equipment (UE) existing in a cell and the Node B, in a system including the Node B, a drift radio network controller (DRNC) connected to the Node B, for managing resource information for communication with UEs existing within the cell occupied by the Node B, and a serving radio network controller (SRNC) connected to the DRNC, for transmitting a control message to the UEs. The method comprises sending a radio link reconfiguration prepare message from the SRNC to the DRNC; transmitting a physical shared channel reconfiguration request message with the total power assigned for an HSDPA (High Speed Downlink Packet Access) service, from the DRNC to the Node B; transmitting a response message for the physical shared channel reconfiguration request message, from the Node B to the DRNC; transmitting a radio link reconfiguration prepare message with HSDPA service-related information, from the DRNC to the Node B; determining, by the Node B, the power offset information considering the total power assigned for the HSDPA service, and transmitting a response message for the radio link reconfiguration prepare message along with the power offset information, to the DRNC; transmitting a radio link reconfiguration prepare message with the power offset information, from the DRNC to the SRNC; and transmitting a radio bearer reconfiguration request message with the power offset information, from the SRNC to the UE. 
   In accordance with a fifth aspect of the present invention, there is provided a method for transmitting power offset information on a high speed physical downlink shared channel in a drift radio network controller (DRNC) to achieve excellent channel performance indication between a user equipment (UE) existing in a cell and a Node B, in a system including the Node B, the DRNC connected to the Node B, for managing resource information for communication with UEs existing within the cell occupied by the Node B, and a serving radio network controller (SRNC) connected to the DRNC, for transmitting a control message to the UEs. The method comprises determining the power offset information considering a ratio of power assigned to a common pilot channel to power assigned to the high speed physical downlink shared channel; transmitting an NBAP (Node B Application Part) message with the power offset information to the Node B; and transmitting an RNSAP (Radio Network System Application Part) message with the power offset information to the SRNC; wherein the SRNC transmits an RRC (Radio Resource Control) message with the power offset information to the UE. 
   In accordance with a sixth aspect of the present invention, there is provided a method for transmitting power offset information on a high speed physical downlink shared channel in a Node B to achieve excellent channel performance indication between a user equipment (UE) existing in a cell and the Node B, in a system including the Node B, a drift radio network controller (DRNC) connected to the Node B, for managing resource information for communication with UEs existing within the cell occupied by the Node B, and a serving radio network controller (SRNC) connected to the DRNC, for transmitting a control message to the UEs. The method comprises receiving information on the total power assigned for an HSDPA (High Speed Downlink Packet Access) service from the DRNC through an NBAP (Node B Application Part) message; determining the power offset information considering a ratio of power assigned to the high speed physical downlink shared channel, determined based on the information on the total power assigned for the HSDPA service, to power assigned to a common pilot channel; and transmitting an NBAP message with the power offset information to the DRNC; wherein the DRNC transmits an RNSAP (Radio Network System Application Part) message with the power offset information to the SRNC, and the SRNC transmits an RRC (Radio Resource Control) message with the power offset information to the UE. 

   
     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  illustrates channels used within a cell of a conventional mobile communication system; 
       FIG. 2  illustrates Node B power assigned to respective channels within a cell of a conventional mobile communication system; 
       FIG. 3  illustrates a structure of an uplink channel supporting HSDPA in a conventional mobile communication system; 
       FIG. 4  illustrates a structure of downlink channels supporting HSDPA in a conventional mobile communication system; 
       FIG. 5  illustrates a process of determining an HS-PDSCH power offset by a CRNC according to an embodiment of the present invention; 
       FIG. 6  illustrates an example of a signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to an embodiment of the present invention; 
       FIG. 7  illustrates another example of a signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to an embodiment of the present invention; 
       FIG. 8  illustrates a process of determining, by a Node B, an HS-PDSCH power offset in a mobile communication system according to another embodiment of the present invention; 
       FIG. 9  illustrates an example of a signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to another embodiment of the present invention; and 
       FIG. 10  illustrates another example of a signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Several preferred embodiments of the present invention will now be described in detail hereinbelow with reference to the annexed drawings. In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness. 
   In the following description, the present invention will provide a method for determining an HS-PDSCH power offset for an HSDPA service and a method for enabling a Node B and a UE to share the determined HS-PDSCH power offset through signal processing. 
   1. First Embodiment 
   In a first embodiment of the present invention, an HS-PDSCH power offset is determined by a CRNC that controls a Node B that transmits the HS-PDSCH. A description will be made of a method for transmitting by the CRNC the HS-PDSCH power offset to a Node B through an NBAP message, and delivering the HS-PDSCH power offset to a UE through an RNSAP (Radio Network System Application Part) or RRC (Radio Resource Control) message. 
   As described in conjunction with the prior art ( FIGS. 1–4 ), the CRNC determines power to be assigned to an HSDPA service within the range of the total power available in the Node B. That is, the CRNC determines the total transmission power that HS-SCCH and HS-PDSCH can use, and then keeps the information. The present invention aims at determining the HS-PDSCH power offset using power to be assigned to the HSDPA service, i.e., the maximum transmission power of HS-SCCH and HS-PDSCH, possessed by the CRNC. In this embodiment, an HS-PDSCH power offset determined by the CRNC is defined as a function of maximum transmission power information of an HS-SCCH and an HS-PDSCH, already determined by the CRNC. That is, the HS-PDSCH power offset is set based on information possessed by the CRNC, such as the maximum transmission power value of HS-SCCH and HS-PDSCH, CPICH transmission power in the Node B, and the total number of HS-PDSCH codes used by the Node B. 
     FIG. 5  illustrates a block for determining an HS-PDSCH power offset according to an embodiment of the present invention. Referring to  FIG. 5 , reference numerals  501 ,  502 ,  503 , and  504  each represent parameters for determining the HS-PDSCH power offset. The parameters are information possessed by the CRNC. The reference numeral  501  indicates information on the total power assigned for an HSDPA service in a Node B. The reference numeral  502  denotes power information of CPICH transmitted from the Node B. The reference numeral  503  indicates a total number of codes used for HS-PDSCH, and the reference numeral  504  represents information possessed by the other CRNCs. Based on the parameters, an HS-PDSCH power offset  506  can be obtained through a particular function  505 . For example, the HS-PDSCH power offset can be determined by Equation (1).
 Power hsdsch =(Max HSDPA Total power−Max HS-SCCH power−margin)/N PO hsdsch =10 log 10 (Power hsdsch /Power cpich )  Equation (1) 
   In Equation (1), Power hsdsch  indicates power per HS-PDSCH code, and Max HSDPA Total power indicates the maximum total transmission power assigned for an HSDPA service. Further, Max HS-SCCH power indicates the maximum transmission power assigned to HS-SCCH, and N denotes the total number of codes used for HS-PDSCH. In addition, Power cpich  represents transmission power assigned to CPICH, and PO hsdsch  represents an HS-PDSCH power offset per code. That is, the PO hsdsch    506  is determined by choosing a function which is in proportion to the Max USDPA Total power information  501  and in inverse proportion to the Power cpich  information  502  and the total number  503  of codes used for the HS-PDSCH. 
   In the embodiment, the HS-PDSCH reference power offset determination block described in conjunction with  FIG. 5  is included in a CRNC. 
   The HS-PDSCH power offset information determined in the way stated above must be transmitted to a Node B and UE. 
     FIGS. 6 and 7  illustrate procedures for delivering an HS-PDSCH power offset determined by the CRNC to a Node B and a UE. In the following description made with reference to  FIGS. 6 and 7 , an “RNSAP message” is used between RNCs, an “NBAP message” is used between a DRNC and a Node B, and an “RRC message” is used between the Node B and a UE. 
     FIG. 6  illustrates a signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to an embodiment of the present invention. As illustrated in  FIG. 6 , a Node B  602  is connected to a DRNC  603  via an lub, and the DRNC  603  is connected to an SRNC (Serving RNC)  604  via an lur. In addition, the DRNC  603  serves as a CRNC of the Node B  602 . 
   Referring to  FIG. 6 , the SRNC  604  sends a Radio Link Setup Request message  610  requesting setup of a radio link, to the DRNC  603 . The Radio Link Setup Request message  610  includes HSDPA-related information to be exchanged between a UE  601  and the Node B  602 . The HSDPA-related information includes HS-DSCH information and HS-PDSCH RL ID (Radio Link Identifier). Upon receiving the RNSAP message  610 , the DRNC  603  (or a CRNC) acquires the HSDPA-related information by analyzing the RNSAP message  610 . The DRNC  603  transmits the acquired HSDPA-related information and additional information possessed by the DRNC  603  to the Node B  602  through a Radio Link Setup Request message  611  requesting setup of a radio link. Information contained in the NBAP message  611  includes HS-DSCH information, HS-PDSCH RL ID, and HS-DSCH-RN. Through the NBAP message  611 , the DRNC (or CRNC)  603  can send a determined HS-PDSCH power offset. If the HS-PDSCH power offset is defined as PO hsdsch , a PO hsdsch  IE can be included in an HS-DSCH Information IE. Table 1 below shows the HS-DSCH Information IE. The PO hsdsch , an IE included in the last row, represents the HS-PDSCH power offset information. IE type and reference of the PO hsdsch  IE is determined according to a possible value of HS-PDSCH power offset information. In this embodiment, it is assumed that a value of 3 to 15 is used for the IE type and reference of the PO hsdsch  IE. Also, the PO hsdsch  information is assumed to be power offset information of an HS-PDSCH using one code. Alternatively, the PO hsdsch  information may be defined as a power offset of all HS-PDSCHs used by one Node B. In this case, the Node B must inform the UE of the number of codes used for the HS-PDSCHs. 
   
     
       
             
           
             
             
             
             
             
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               HS-DSCH FDD Information 
             
           
        
         
             
                 
                 
                 
               IE type 
                 
                 
                 
             
             
                 
                 
                 
               and 
               Semantics 
               Criti- 
               Assigned 
             
             
               IE/Group Name 
               Presence 
               Range 
               reference 
               description 
               cality 
               Criticality 
             
             
                 
             
             
               HS-DSCH MAC-d Flow 
                 
               1 . . . &lt;Maxno 
                 
                 
               — 
                 
             
             
               Specific Information 
                 
               ofMACdFl- 
             
             
                 
                 
               ows&gt; 
             
             
               &gt;HS-DSCH MAC-d Flow ID 
               M 
                 
               9.2.1.31I 
                 
               — 
             
             
               &gt;BLER 
               M 
                 
               9.2.1.4A 
                 
               — 
             
             
               &gt;Allocation/Retention 
               M 
                 
               9.2.1.1A 
                 
               — 
             
             
               Priority 
                 
                 
             
             
               &gt;Priority Queue 
               M 
               1 . . . &lt;Maxno 
                 
                 
               — 
             
             
               Information 
                 
               ofPrioQue- 
             
             
                 
                 
               ues&gt; 
             
             
               &gt;&gt;Priority Queue ID 
               M 
                 
               9.2.1.49C 
                 
               — 
             
             
               &gt;&gt;Scheduling Priority 
               M 
                 
               9.2.1.53H 
                 
               — 
             
             
               Indicator 
             
             
               &gt;&gt;MAC-d PDU Size Index 
                 
               1 . . . &lt;Maxno 
                 
                 
               — 
             
             
                 
                 
               ofMACdP 
             
             
                 
                 
               DUindexes&gt; 
             
             
               &gt;&gt;&gt;SID 
               M 
                 
               9.2.1.53I 
                 
               — 
             
             
               &gt;&gt;&gt;MAC-d PDU Size 
               M 
                 
               9.2.1.38A 
                 
               — 
             
             
               UE Capabilities information 
                 
               1 
                 
                 
               — 
             
             
               &gt;Max TrCH Bits per HS- 
               M 
                 
               ENUMERA- 
             
             
               DSCH TTI 
                 
                 
               TED 
             
             
                 
                 
                 
               (7300, 
             
             
                 
                 
                 
               14600, 
             
             
                 
                 
                 
               20456, 
             
             
                 
                 
                 
               28800, . . . ) 
             
             
               &gt;HS-DSCH multi-code 
               M 
                 
               ENUMERA- 
                 
               — 
             
             
               capability 
                 
                 
               TED (5, 
             
             
                 
                 
                 
               10, 15, . . . ) 
             
             
               &gt;Min Inter-TTI Interval 
               M 
                 
               INTEGER 
                 
               — 
             
             
                 
                 
                 
               (1 . . . 3, . . . ) 
             
             
               &gt;MAC-hs reordering buffer 
               M 
                 
               INTEGER 
               Total 
               — 
             
             
               size 
                 
                 
               (1 . . . 300, . . . ) 
               combined 
             
             
                 
                 
                 
                 
               receiving 
             
             
                 
                 
                 
                 
               buffer 
             
             
                 
                 
                 
                 
               capability in 
             
             
                 
                 
                 
                 
               RLC and 
             
             
                 
                 
                 
                 
               MAC-hs in 
             
             
                 
                 
                 
                 
               kBytes 
             
             
               HARQ memory partitioning 
                 
               1 . . . &lt;Maxno 
                 
                 
               — 
             
             
                 
                 
               ofHARQpr- 
             
             
                 
                 
               ocesses&gt; 
             
             
               &gt;Process memory size 
               M 
                 
               INTEGER 
                 
               — 
             
             
                 
                 
                 
               (1 . . . 
             
             
                 
                 
                 
               172800, . . . ) 
             
             
               Measurement feedback offset 
               M 
                 
               INTEGER 
                 
               — 
             
             
                 
                 
                 
               (0 . . . 79, . . . ) 
             
             
               POhsdsch 
               M 
                 
               Integer(- 
               Default 
               — 
             
             
                 
                 
                 
               3 . . . 15) 
               Power offset 
             
             
                 
                 
                 
                 
               between HS- 
             
             
                 
                 
                 
                 
               PDSCH and 
             
             
                 
                 
                 
                 
               P-CPICH/S- 
             
             
                 
                 
                 
                 
               CPICH. In 
             
             
                 
                 
                 
                 
               dB. 
             
             
                 
             
           
        
       
     
   
   As described above, the PO hsdsch  information is transmitted to the Node B  602  through the Radio Link Setup Request message  611 . Upon receiving the NBAP message  611 , the Node B  602  sends a Radio Link Setup Response message  612  to the DRNC  603 , acknowledging the receipt of the Radio Link Setup Request message  611 . The DRNC  603  then transmits a Radio Link Setup Response message  613  to the SRNC  604 , using the Radio Link Setup Request message  611  and information possessed by the DRNC  603 . The RNSAP message  613  includes an HS-DSCH Information Response IE, and the HS-DSCH Information Response IE has the determined PO hsdsch  information. Table 2 below shows detailed information of the HS-DSCH Information Response IE. In Table 2, PO hsdsch  included in the HS-DSCH Information Response IE is the same information as PO hsdsch  in the HS-DSCH Information IE included in the NBAP message  611 . 
   
     
       
             
           
             
             
             
             
             
             
             
           
         
             
               TABLE 2 
             
           
           
             
                 
             
             
               HS-DSCH FDD Information Response 
             
           
        
         
             
                 
                 
                 
               IE type 
                 
                 
                 
             
             
                 
                 
                 
               and 
               Semantics 
               Criti- 
               Assigned 
             
             
               IE/Group Name 
               Presence 
               Range 
               reference 
               description 
               cality 
               Criticality 
             
             
                 
             
             
               HS-DSCH MAC-d Flow 
                 
               1 . . . &lt;maxno 
                 
                 
               — 
                 
             
             
               Specific Information 
                 
               ofMACdFl- 
             
             
               Response 
                 
               ows&gt; 
             
             
               &gt;HS-DSCH MAC-d Flow ID 
               M 
                 
               9.2.1.30O 
                 
               — 
             
             
               &gt;Binding ID 
               O 
                 
               9.2.1.4 
                 
               — 
             
             
               &gt;Transport Layer Address 
               O 
                 
               9.2.1.63 
                 
               — 
             
             
               HS-SCCH Specific 
                 
               1 . . . &lt;maxno 
             
             
               Information Response 
                 
               ofHSSCC 
             
             
                 
                 
               Hcodes&gt; 
             
             
               &gt;Code Number 
               M 
                 
               INTEGER 
             
             
                 
                 
                 
               (0 . . . 127) 
             
             
               Measurement feedback 
               M 
                 
               Measure- 
               used by the 
             
             
               reporting cycle k1 
                 
                 
               ment 
               UE when not 
             
             
                 
                 
                 
               Feedback 
               in soft 
             
             
                 
                 
                 
               Reporting 
               handover 
             
             
                 
                 
                 
               Cycle 
             
             
                 
                 
                 
               9.2.2.24a 
             
             
               Measurement feedback 
               M 
                 
               Measure- 
               used by the 
             
             
               reporting cycle k2 
                 
                 
               ment 
               UE when in 
             
             
                 
                 
                 
               Feedback 
               soft 
             
             
                 
                 
                 
               Reporting 
               handover 
             
             
                 
                 
                 
               Cycle 
             
             
                 
                 
                 
               9.2.2.24a 
             
             
               POhsdsch 
               M 
                 
               Integer(- 
               Default 
               — 
             
             
                 
                 
                 
               3 . . . 15) 
               Power offset 
             
             
                 
                 
                 
                 
               between HS- 
             
             
                 
                 
                 
                 
               PDSCH and 
             
             
                 
                 
                 
                 
               P-CPICH/S- 
             
             
                 
                 
                 
                 
               CPICH. In 
             
             
                 
                 
                 
                 
               dB. 
             
             
                 
             
           
        
       
     
   
   Upon receiving the RNSAP message  613 , the SRNC  604  generates a Radio Bearer Setup message  614  requesting setup of a radio bearer, using the RNSAP message  613  and other information, and then transmits the generated Radio Bearer Setup message  614  to the UE  601 . The RRC message  614  also includes PO hsdsch  information transmitted from the DRNC (or CRNC)  603  through the RNSAP message  613 . The UE  601 , as it receives the RRC message  614 , can receive the PO hsdsch  information determined by the DRNC  603 . 
   Upon receiving the Radio Bearer Setup message  614 , the UE  601  sends a Radio Bearer Setup Complete message  615  indicating completed setup of a radio bearer to the SRNC  604 , thereby informing the SRNC  604  that it can receive an HSDPA service. As a result, the UE  601  and the Node B  602  share the HS-PDSCH power offset information. Therefore, an operation of determining CQI by a UE, and an operation of receiving by a Node B the CQI and then transmitting HS-DSCH depending on the received CQI is effectively performed. 
   In the signaling procedure of  FIG. 6 , the messages represented by a bold arrow indicate the signals over which the PO hsdsch  information is transmitted. 
     FIG. 7  illustrates another signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to an embodiment of the present invention. That is,  FIG. 7  illustrates a signaling procedure when a UE  701  initiates an HSDPA service during communication with a Node B  702  over a dedicated channel, or when the setup must be changed during the HSDPA service. 
   Referring to  FIG. 7 , an SRNC  704  transmits a Radio Link Reconfiguration Prepare message  710  requesting preparation for radio link reconfiguration, to a DRNC  703 , thereby providing the DRNC  703  with information related to an HSDPA to be serviced. The DRNC  703  (or a CRNC in this embodiment) determines HS-PDSCH power offset information through the block described in conjunction with  FIG. 5 . Thereafter, the DRNC  703  generates a Radio Link Reconfiguration Prepare message  711  including information received through the RNSAP message  710  and other information, and transmits the generated Radio Link Reconfiguration Prepare message  711  to a Node B  702 , thereby requesting reconfiguration of a radio link. The NBAP message  711  includes PO hsdsch  information, the HS-PDSCH power offset information. The PO hsdsch  information is included in HS-DSCH Information to Add IE, when an HSDPA service is added. However, when setup of an HSDPA service is modified, the PO hsdsch  information is included in HS-DSCH Information to modify IE. The HS-DSCH Information to Add IE is identical in structure to the HS-DSCH FDD Information IE included in the NBAP message  611 , described in conjunction with  FIG. 6 . On the contrary, the HS-DSCH Information to modify IE is formed as illustrated in Table 3, and is identical in format of the PO hsdsch  information included therein to the HS-DSCH FDD Information IE. 
   
     
       
             
           
             
             
             
             
             
             
             
           
         
             
               TABLE 3 
             
           
           
             
                 
             
             
               HS-DSCH Information to modify 
             
           
        
         
             
                 
                 
                 
               IE type 
                 
                 
                 
             
             
                 
                 
                 
               and 
               Semantics 
               Criti- 
               Assigned 
             
             
               IE/Group Name 
               Presence 
               Range 
               reference 
               description 
               cality 
               Criticality 
             
             
                 
             
             
               HS-DSCH MAC-d Flow 
                 
               0 . . . &lt;Maxno 
                 
                 
               — 
                 
             
             
               Specific Information 
                 
               ofMACdFl- 
             
             
                 
                 
               ows&gt; 
             
             
               &gt;HS-DSCH MAC-d Flow ID 
               M 
                 
               9.2.131I 
                 
               — 
             
             
               &gt;BLER 
               O 
                 
               9.2.1.4A 
                 
               — 
             
             
               &gt;Allocation/Retention 
               O 
                 
               9.2.1.1A 
                 
               — 
             
             
               Priority 
             
             
               &gt;Priority Queue 
                 
               0 . . . &lt;Maxno 
                 
                 
               — 
             
             
               Information 
                 
               ofPrioQue- 
             
             
                 
                 
               ues&gt; 
             
             
               &gt;&gt;Priority Queue ID 
               M 
                 
               9.2.1.49C 
                 
               — 
             
             
               &gt;&gt;Scheduling Priority 
               O 
                 
               9.2.1.53H 
                 
               — 
             
             
               Indicator 
             
             
               &gt;&gt;MAC-d PDU Size Index 
                 
               0 . . . &lt;Maxno 
                 
                 
               — 
             
             
                 
                 
               ofMACdP 
             
             
                 
                 
               DUindexes&gt; 
             
             
               &gt;&gt;&gt;SID 
               M 
                 
               9.2.1.53I 
                 
               — 
             
             
               &gt;&gt;&gt;MAC-d PDU Size 
               O 
                 
               9.2.1.38A 
                 
               — 
             
             
               &gt;Transport Bearer Request 
               M 
                 
               9.2.1.62A 
                 
               — 
             
             
               Indicator 
                 
                 
             
             
               Measurement Reporting cycle 
               O 
                 
               ENUMERA 
               For FDD 
               — 
             
             
                 
                 
                 
               TED (k1, 
               only 
             
             
                 
                 
                 
               k2) 
             
             
               POhsdsch 
               O 
                 
               Integer(- 
               Default 
             
             
                 
                 
                 
               3 . . . 15) 
               Power offset 
             
             
                 
                 
                 
                 
               between HS- 
             
             
                 
                 
                 
                 
               PDSCH and 
             
             
                 
                 
                 
                 
               P-CPICH/S- 
             
             
                 
                 
                 
                 
               CPICH. In 
             
             
                 
                 
                 
                 
               dB. 
             
             
                 
             
           
        
       
     
   
   The Node B  702 , receiving the NBAP message  711 , acquires PO hsdsch  information included in the received NBAP message  711 , and sends a Radio Link Reconfiguration Ready message  712  indicating completed preparation for radio link reconfiguration to the DRNC  703 . Upon receiving the NBAP message  712 , the DRNC  703  transmits a Radio Link Reconfiguration Ready message  713  indicating completed preparation for radio link reconfiguration to the SRNC  704 . The PO hsdsch  information is transmitted through the RNSAP message  713 . For an IE including the PO hsdsch  information, an HS-DSCH FDD Information Response IE in the Radio Link Setup Response message of  FIG. 6  is used. A detailed structure of the HS-DSCH FDD Information Response IE has been described with reference to  FIG. 6 . 
   Upon receiving the RNSAP message  713 , the SRNC  704  sends a Radio Link Reconfiguration Commit message  714  committing reconfiguration of a radio link, to the DRNC  703 . The DRNC  703  then sends a Radio Link Reconfiguration Commit message  715  committing reconfiguration of a radio link, to the Node B  702 , thereby enabling the Node B  702  to perform a radio link reconfiguration process. 
   The SRNC  704  sends the PO hsdsch  information to the UE  701  through a Radio Bearer Reconfiguration message  716  requesting reconfiguration of a radio bearer. Upon receiving the RRC message  716 , the UE  701  reconfigures a radio bearer through a radio bearer reconfiguration procedure. If the radio bearer reconfiguration is completed, the UE  701  sends a Radio Bearer Reconfiguration Complete message  717  indicting completed reconfiguration of a radio bearer to the SNC  704 , completing the signaling procedure of  FIG. 7 . 
   Also, in the signaling procedure described in conjunction with  FIG. 7 , messages represented by a bold arrow indicate the signals over which the PO hsdsch  information is transmitted. 
   In this embodiment, in some cases, the PO hsdsch  information, though not frequently, is subject to change. Each time a new UE desiring to receive a service is added to the Node B or a UE that was receiving a service is reset, the Node B updates the PO hsdsch  information. If the PO hsdsch  information is changed, the Node B can simply identify the changed PO hsdsch  information. However, a process of providing the changed PO hsdsch  information to the UEs that were previously receiving the HSDPA service from the Node B is additionally required. For this, there are two possible methods. In a first method, the UE may use the existing PO hsdsch  information. In a second method, the Node B can provide the PO hsdsch  information to all UEs currently in service through the message handling process of the radio link reconfiguration procedure described in conjunction with  FIG. 7 . 
   2. Second Embodiment 
   In a second embodiment of the present invention, it is assumed that the HS-PDSCH power offset is determined by a Node B that transmits the HS-PDSCH. The Node B determines an HS-PDSCH power offset, using HSDPA power information received from a CRNC through an NBAP message. A description will be made of a method in which the Node B re-transmits the HS-PDSCH power offset to an SRNC through an NBAP message and an RNSAP message, and the SRNC re-transmits the HS-PDSCH power offset to a UE through an RRC message. 
   Commonly, a CRNC determines the total power to be assigned for an HSDPA service within the range of the total power of a Node B. That is, the CRNC determines the maximum transmission power that HS-SCCH and HS-PDSCH can use, and then stores the information. The present invention is characterized in that the CRNC provides a Node B with information on the total power to be assigned for an HSDPA service, i.e., information on the maximum transmission power of HS-SCCH and HS-PDSCH, and the Node B then determines the HS-PDSCH power offset based on the total power information assigned for the HSDPA service. In this embodiment, an HS-PDSCH power offset is defined as a function of maximum transmission power information of HS-SCCH and HS-PDSCH, already determined by the CRNC. That is, the HS-PDSCH power offset is set based on information possessed by the CRNC, such as the maximum transmission power value of HS-SCCH and HS-PDSCH, received from the CRNC through an NBAP message, CPICH transmission power in the Node B, and the total number of HS-PDSCH codes used by the Node B. 
     FIG. 8  illustrates a process of determining, by a Node B, an HS-PDSCH power offset in a mobile communication system according to another embodiment of the present invention. Specifically,  FIG. 8  is a block diagram for determining the HS-PDSCH power offset. 
   Referring to  FIG. 8 , reference numerals  801 ,  802 ,  803 , and  804  each represent parameters for determining the HS-PDSCH power offset. The parameters are information possessed by the CRNC. Of the parameters, the maximum transmission power of HS-SCCH and HS-PDSCH, represented by the reference numeral  801 , is information that the Node B received from a CRNC through a Physical Shared Channel Reconfiguration Request message  810 . The other parameters represented by the reference numerals  802 ,  803  and  804  are information possessed by the Node B. The reference numeral  801  indicates information on the total power assigned for an HSDPA service in a Node B in service. The reference numeral  802  denotes power information of CPICH transmitted from the Node B. The reference numeral  803  indicates the total number of codes available for HS-PDSCH, and the reference numeral  804  represents information possessed by the other CRNCs. Based on the parameters, an HS-PDSCH power offset  806  can be calculated through a particular function  805 . For example, the HS-PDSCH power offset can be determined by Equation (2).
 
Power hsdsch =(Max HSDPA Total power−Max HS-SCCH power−margin)/N PO hsdsch =10 log 10 (Power hsdsch /Power cpich )  Equation (2)
 
   In Equation (2), Power hsdsch  indicates power per HS-PDSCH code, and Max HSDPA Total power indicates the maximum total transmission power assigned for an HSDPA service. Further, Max HS-SCCH power indicates the maximum transmission power assigned to HS-SCCH, and N denotes the total number of codes used for HS-PDSCH. In addition, Power hsdsch  represents transmission power assigned to CPICH, and PO hsdsch  represents an HS-PDSCH power offset per code. That is, the PO hsdsch    806  is determined by choosing a function in proportion to the Max HSDPA Total power information  801  and in inverse proportion to the Power cpich  information  802  and a total number  803  of codes used for the HS-PDSCH. 
   In the second embodiment of the present invention, the HS-PDSCH reference power offset determination block described in conjunction with  FIG. 8  is included in a Node B. In the process illustrated in  FIG. 8 , after determining an HS-PDSCH power offset, the Node B must transmit information on the HS-PDSCH power offset to a UE. 
     FIGS. 9 and 10  illustrate examples of procedures for delivering an HS-PDSCH power offset determined by the Node B to a UE. In the following description made with reference to  FIGS. 9 and 10 , an “RNSAP message” is used between RNCs, an “NBAP message” is used between a DRNC and a Node B, and an “RRC message” is used between the Node B and a UE. 
     FIG. 9  illustrates an example of a signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to another embodiment of the present invention. As illustrated in  FIG. 9 , a Node B  902  is connected to a DRNC  903  via an lub, and the DRNC  903  is connected to an SRNC  904  via an lur. In addition, the DRNC  903  serves as a CRNC of the Node B  902 . 
   Referring to  FIG. 9 , the SRNC  904  sends a Radio Link Setup Request message  910  requesting setup of a radio link, to the DRNC  903 . The Radio Link Setup Request message  910  includes an HSDPA-related IE, HS-DSCH-related information to be exchanged between a UE  901  and the Node B  902 . The HSDPA-related information includes HS-DSCH information and HS-PDSCH RL ID. Upon receiving the RNSAP message  910 , the DRNC  903  (or a CRNC) delivers maximum transmission power information of HS-SCCH and HS-PDSCH to the Node B  902  through a Physical Shared Channel Reconfiguration Request message  920  requesting reconfiguration of a physical shared channel. Upon receiving the NBAP message  920 , the Node B  902  stores information included in the Physical Shared Channel Reconfiguration Request message  920 , and then transmits a Physical Shared Channel Reconfiguration Response message  921  to the DRNC  903 . The NBAP messages  920  and  921  can be transmitted after the SRNC  904  transmitted an RNSAP message of the Radio Link Setup Request message  910  to the DRNC  903 , or can be exchanged on occasion between the DRNC  903  and the Node B  902  according to a condition of the DRNC  903 . 
   The Physical Shared Channel Reconfiguration Request message  920  includes an HS-PDSCH and HS-SCCH Total Power IE, and the HS-PDSCH and HS-SCCH Total Power IE becomes the maximum transmission power information of HS-SCCH and HS-PDSCH described in conjunction with  FIG. 8 . That is, the Node B  902  has the maximum transmission power information of HS-SCCH and HS-PDSCH. 
   The DRNC  903 , after receiving the RNSAP message  910 , acquires HSDPA-related information by analyzing the RNSAP message  910 , and then transmits the acquired information and additional information possessed by the DRNC  903  to the Node B  902  through a Radio Link Setup Request message  911  requesting setup of a radio link. An HSDPA-related IE included in the NBAP message  911  includes HS-DSCH Information, HS-PDSCH RL ID, and HS-DSCH-RN. 
   If the HSDPA-related information is delivered to the Node B  902  through the Radio Link Setup Request message  911 , the Node B  902  generates HS-PDSCH power offset information. That is, since the Node B  902  has information on each of the reference numerals  801 ,  802 ,  803 , and  804 , it can generate the HS-PDSCH power offset information  806 . Thus, the Node B  902  starts an operation of delivering the generated HS-PDSCH power offset information to the UE  901 . 
   Upon receiving the NBAP message  911 , the Node B  902  sends a Radio Link Setup Response message  912  to the DRNC  903  in response to the NBAP message  911 . The Node B  902  can transmit the determined HS-PDSCH power offset value along with the NBAP message  912 . If the HS-PDSCH power offset is defined as PO hsdsch , a PO hsdsch  IE can be included in an HS-DSCH Information IE. Table 4 below shows an HS-DSCH Information IE included in the Radio Link Setup Response message  912 . The PO hsdsch , an IE included in the last row, represents the HS-PDSCH power offset information. IE type and reference of the PO hsdsch  IE is determined according to a possible value of the HS-PDSCH power offset information. In this embodiment, it is assumed that a value of 3 to 15 is used for the IE type and reference of the PO hsdsch  IE. Also, the PO hsdsch  information is assumed to be power offset information of HS-PDSCH using one code. Alternatively, the PO hsdsch  information can also be defined as a power offset of all HS-PDSCHs used by one Node B. In this case, the Node B must inform the UE of the number of codes used for the HS-PDSCHs. 
   
     
       
             
           
             
             
             
             
             
             
             
           
         
             
               TABLE 4 
             
           
           
             
                 
             
             
               HS-DSCH FDD Information Response 
             
           
        
         
             
                 
                 
                 
               IE type 
                 
                 
                 
             
             
                 
                 
                 
               and 
               Semantics 
               Criti- 
               Assigned 
             
             
               IE/Group Name 
               Presence 
               Range 
               reference 
               description 
               cality 
               Criticality 
             
             
                 
             
             
               HS-DSCH MAC-d Flow 
                 
               1 . . . &lt;Maxno 
                 
                 
               — 
                 
             
             
               Specific Information 
                 
               ofMACdFl- 
             
             
               Response 
                 
               ows&gt; 
             
             
               &gt;HS-DSCH MAC-d Flow ID 
               M 
                 
               9.2.1.31I 
                 
               — 
             
             
               &gt;Binding ID 
               O 
                 
               9.2.1.4 
                 
               — 
             
             
               &gt;Transport Layer Address 
               O 
                 
               9.2.1.63 
                 
               — 
             
             
               HS-SCCH Code 
                 
               1 . . . &lt;Maxno 
             
             
                 
                 
               ofHSSCC 
             
             
                 
                 
               Hcodes&gt; 
             
             
               &gt;Code Number 
               M 
                 
               INTEGER 
             
             
                 
                 
                 
               (0 . . . 127) 
             
             
               Measurement feedback 
               M 
                 
               Measure- 
               employed by 
               — 
             
             
               reporting cycle k1 
                 
                 
               ment 
               the UE when 
             
             
                 
                 
                 
               Feedback 
               not in soft 
             
             
                 
                 
                 
               Reporting 
               handover 
             
             
                 
                 
                 
               Cycle 
             
             
                 
                 
                 
               9.2.2.21B 
             
             
               Measurement feedback 
               M 
                 
               Measure- 
               employed by 
               — 
             
             
               reporting cycle k2 
                 
                 
               ment 
               the UE when 
             
             
                 
                 
                 
               Feedback 
               in soft 
             
             
                 
                 
                 
               Reporting 
               handover 
             
             
                 
                 
                 
               Cycle 
             
             
                 
                 
                 
               9.2.2.21B 
             
             
               POhsdsch 
               M 
                 
               Integer(- 
               Default 
               — 
             
             
                 
                 
                 
               3 . . . 15) 
               Power offset 
             
             
                 
                 
                 
                 
               between HS- 
             
             
                 
                 
                 
                 
               PDSCH and 
             
             
                 
                 
                 
                 
               P-CPICH/S- 
             
             
                 
                 
                 
                 
               CPICH. In 
             
             
                 
                 
                 
                 
               dB. 
             
             
                 
             
           
        
       
     
   
   The DRNC  903  sends a Radio Link Setup Response message  913  to the SRNC  904 , using information included in the Radio, Link Setup Response message  912 . Because the DRNC  903  has received the PO hsdsch  information through the Radio Link Setup Response message  912 , the RNSAP message  913  includes an HS-DSCH Information Response IE, so the DRNC  903  can transmit the PO hsdsch  information to the SRNC  904  along with the HS-DSCH Information Response IE. Detailed information on the HS-DSCH Information Response IE is identical to the format described in conjunction with the first embodiment. The PO hsdsch  included in the HS-DSCH Information Response IE is the same information as PO hsdsch  in the HS-DSCH Information IE included in the NBAP message  911 . 
   Upon receiving the RNSAP message  913 , the SRNC  904  generates a Radio Bearer Setup message  914  requesting setup of a radio bearer, using the RNSAP message  913  and other information, and transmits the generated Radio Bearer Setup message  914  to the UE  901 . The RRC message  914  also includes PO hsdsch  information transmitted from the DRNC (or CRNC)  903  to the SRNC  904  through the RNSAP message  913 . The UE  901 , as it receives the RRC message  914 , can receive the PO hsdsch information determined by the Node B  902 . 
   Upon receiving the Radio Bearer Setup message  914 , the UE  901  performs a procedure for setup of a radio bearer and then sends a Radio Bearer Setup Complete message  915  indicating completed setup of a radio bearer to the SRNC  904 , thereby informing the SRNC  904  that it can receive an HSDPA service. As a result, the UE  901  and the Node B  902  share the HS-PDSCH power offset information. Therefore, an operation of determining CQI by a UE, and an operation of receiving by a Node B the CQI and then transmitting HS-DSCH depending on the received CQI can be smoothly performed. 
   In the signaling procedure of  FIG. 9 , the messages  912 ,  913 , and  914  represented by a bold arrow are the signals transmitting the PO hsdsch  information. 
     FIG. 10  illustrates another signaling procedure for delivering HS-PDSCH power offset information in a mobile communication system according to another embodiment of the present invention. That is,  FIG. 10  illustrates a signaling procedure when a UE  1001  initiates an HSDPA service during communication with a Node B  1002  over a dedicated channel, or when the setup must be changed during the HSDPA service. 
   Referring to  FIG. 10 , an SRNC  1004  transmits a Radio Link Reconfiguration Prepare message  1010  requesting preparation for radio link reconfiguration, to a DRNC  1003 , thereby providing the DRNC  1003  with information related to an HSDPA to be serviced. Upon receiving the RNSAP message  1010 , the DRNC  1003  (or a CRNC) transmits maximum transmission power information of an HS-SCCH and an HS-PDSCH to a Node B  1002  through a Physical Shared Channel Reconfiguration Request message  1020  requesting reconfiguration of a physical shared channel. Upon receiving the NBAP message  1020 , the Node B  1002  stores information included in the Physical Shared Channel Reconfiguration Request message  1020 , and then transmits a Physical Shared Channel Reconfiguration Response message  1021  to the DRNC  1003 . The NBAP messages  1020  and  1021  can be transmitted after the SRNC  1004  transmitted an RNSAP message of the Radio Link Reconfiguration Prepare message  1010  to the DRNC  1003 , or can be exchanged on occasion between the DRNC  1003  and the Node B  1002  according to a condition of the DRNC  1003 . 
   The Physical Shared Channel Reconfiguration Request message  1020  includes an HS-PDSCH and HS-SCCH Total Power IE, and the HS-PDSCH and HS-SCCH Total Power IE becomes the maximum transmission power information  801  of HS-SCCH and HS-PDSCH. That is, the Node B  1002  has the maximum transmission power information of HS-SCCH and HS-PDSCH. 
   The DRNC  1003  that received the Radio Link Reconfiguration Prepare message  1010 , generates a Radio Link Reconfiguration Prepare message  1011  for preparation for reconfiguration of a radio link, using information received through the RNSAP message  1010  and other information, and then transmits the generated Radio Link Reconfiguration Prepare message  1011  to the Node B  1002 . An HSDPA-related IE included in the NBAP message  1011  includes HS-DSCH Information, HS-PDSCH RL ID, and HS-DSCH-RN. 
   If the HSDPA-related information is delivered to the Node B  1002  through the Radio Link Reconfiguration Prepare message  1011 , the Node B  1002  generates HS-PDSCH power offset information. That is, since the Node B  1002  has information on each of the reference numerals  801 ,  802 ,  803 , and  804  of  FIG. 8 , it can generate the HS-PDSCH power offset information  806 . Thus, the Node B  1002  starts an operation of delivering the generated HS-PDSCH power offset information to the UE  1001 . 
   The Node B  1002 , receiving the NBAP message  1011 , acquires HSDPA-related information included in the received NBAP message  1011 , and sends a Radio Link Reconfiguration Ready message  1012  indicating completed preparation for a radio link reconfiguration to the DRNC  1003 , in response to the NBAP message  1011 . The NBAP message  1012  is transmitted along with PO hsdsch  information, HS-PDSCH power offset information determined by the Node B  1002 . The PO hsdsch  information is included in an HS-DSHC Information Response IE in the Radio Link Reconfiguration Ready message  1012  before being transmitted. The HS-DSHC Information Response IE is identical in structure to the IE described in conjunction with  FIG. 9 . 
   Upon receiving the NBAP message  1012 , the DRNC  1003  stores PO hsdsch  information included in the NBAP  1012 . The DRNC  1003  transmits the stored PO hsdsch  information to the SRNC  1004  through a Radio Link Reconfiguration Ready message  1013  indicating completed preparation for radio link reconfiguration. For an IE including the PO hsdsch  information, an HS-DSCH FDD Information Response IE in the Radio Link Setup Response message illustrated in  FIG. 6  is used. A detailed structure of the HS-DSCH FDD Information Response IE has been described with reference to  FIG. 6 . 
   Upon receiving the RNSAP message  1013 , the SRNC  1004  sends a Radio Link Reconfiguration Commit message  1014  committing reconfiguration of a radio link, to the DRNC  1003 . The DRNC  1003  then sends a Radio Link Reconfiguration Commit message  1015  to the Node B  1002 , thereby enabling the Node B  1002  to perform a radio link reconfiguration process. 
   The SRNC  1004  sends the PO hsdsch  information to the UE  1001  through a Radio Bearer Reconfiguration message  1016  requesting reconfiguration of a radio bearer. Upon receiving the RRC message  1016 , the UE  1001  performs a procedure for reconfiguring a radio bearer. Thereafter, the UE  1001  sends a Radio Bearer Reconfiguration Complete message  1017  indicting completed reconfiguration of a radio bearer to the SNC  1004  in response to the RRC message  1016 , completing the signaling procedure of  FIG. 10 . 
   Also, in the signaling procedure described in conjunction with  FIG. 10 , messages  1012 ,  1013 , and  1016  represented by a bold arrow indicates the signals over which the PO hsdsch  information is transmitted. 
   In this embodiment, in some cases, the PO hsdsch  information, though not frequently, is subject to change. Each time a new UE desiring to receive a service is added to the Node B or the UE  1001  that was receiving a service is reset, the Node B  1002  updates the PO hsdsch  information. If the PO hsdsch  information is changed, the Node B  1002  can simply identify the changed PO hsdsch  information. However, a process of providing the changed PO hsdsch  information to the UEs  1001  that were previously receiving the HSDPA service from the Node B  1002  is additionally required. In this case, there are two possible methods. In a first method, the UE  1001  can use the existing PO hsdsch  information. In a second method, the Node B  1002  can provide the PO hsdsch  information to all UE  1001  currently in service through the message handling process of the radio link reconfiguration procedure described in conjunction with  FIG. 10 . 
   As described above, in an HSDPA system, a Node B determines power assigned to each HS-PDSCH, so that the Node B and a UE can accurately determine power to be assigned to an HS-PDSCH, contributing to an increase in entire performance of the HSDPA system. 
   While the 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 invention as defined by the appended claims.