Patent Publication Number: US-2012028644-A1

Title: Mobile communication system, interference of neighborhood suppression method and base station in the system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/367,316, filed on Feb. 6, 2009, which is a continuation of International Application No. PCT/CN2007/001429, filed on Apr. 28, 2007. The International Application claims priority to Chinese Patent Application No. 200610110573.5, filed on Aug. 8, 2006. The afore-mentioned patent applications are hereby incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the mobile communication field, especially to a neighboring cell interference suppression technique, and in particular to a mobile communication system, a neighboring cell interference suppression method and a base station in the mobile communication system. 
     BACKGROUND OF THE INVENTION 
     As an important organization in the mobile communication field, the 3 rd  Generation Partnership Project (3GPP) has driven the standardization of the 3rd Generation (3G) mobile communication techniques. In the earlier versions of 3GPP, both uplink and downlink services are carried out through dedicated channels; and in Release 99 (R99), both the uplink and the downlink transmission rates could reach to 384 Kbps. 
     With the development of the mobile communication techniques, the 3G techniques are also developing and evolving continuously. In 3GPP Release 6 (R6), a High Speed Uplink Packet Access (HSUPA) technique is introduced. The HSUPA technique employs a shorter Transmission Time Interval (TTI) and frame length (2 ms or 10 ms) to implement fast self-adaptive control, and employs a Hybrid Automatic Retransmission Request (HARQ) and base station (NodeB) based fast uplink dispatching technique to improve uplink frequency spectrum efficiency. 
     In the HSUPA technique, in order to implement an efficient uplink data transmission and uplink power control, two uplink physical channels and three downlink physical channels are added, namely: an uplink Enhanced-DCH Dedicated Physical Data Channel (E-DPDCH) designed to carry subscriber data; an uplink Enhanced-DCH Dedicated Physical Control Channel (E-DPCCH) designed to transmit associated physical layer signaling and provide the associated signaling for E-DPDCH demodulation; an Enhanced-DCH Absolute Grant Channel (E-AGCH) and an Enhanced-DCH Relative Grant Channel (E-RGCH), designed to control a subscriber&#39;s uplink data transmission rate; and an Enhanced-DCH Hybrid ARQ Indicator Channel (E-HICH) designed to indicate whether a uplink data transmission is correct. 
     The E-AGCH only exists in a serving radio access cell, and is designed to indicate a maximum uplink transmission rate, and can be adjusted at a low frequency; the E-RGCH may exist in a serving radio access cell or a non-serving radio access cell, and is designed to instruct a subscriber to adjust an uplink transmission rate with a certain step length, and can be adjusted at a higher frequency up to a maximum of once per TTI. In the HSUPA technique, the subscriber learns from the E-HICH whether data is received correctly or not. If the data is not received correctly, a retransmission is initiated; otherwise, new data is transmitted. 
     At the same time when the HSUPA technique is introduced, the 3GPP launches a Long Term Evolution (LTE) project in the second half-year of 2004 in order to ensure competitive force thereof for a longer period (for example, 10 years or longer). 
     During the evolution process of the LTE, the three-layer nodal network structure (NodeB, Radio Network Controller (RNC), and Core Net (CN) in the existing Wideband Code Division Multiple Access (WCDMA) network is simplified into a two-layer nodal structure, in which the RNC function is distributed to NodeBs (here referred to as Evolved NodeB, also as eNodeB)) and nodes on higher layers (e.g., Gateway (GW)). 
     Similar to the NodeB in the existing WCDMA network, each eNodeB covers one or more cells, with neighboring cells overlapping partially (up to about 30%) at the borders thereof. 
     In the WCDMA network, when a User Equipment (UE) moves from a source cell towards a target cell, the strength of signals from the source cell diminishes; therefore, cross-cell handover needs to be carried out in the overlap area between the source cell and the target cell. The UE in the cross-cell handover state communicates with multiple NodeBs involved in the cross-cell handover, i.e., the UE can receive signals from the NodeBs in different cells and can also transmit signals to the NodeBs in different cells. As shown in  FIG. 1 , the UE in the cross-cell handover state establishes connections to the NodeBs in the three neighboring cells  101 ,  102 , and  103 ; a signal transmitted from the UE is received by the three NodeBs via uplink channels and transmitted to the RNC (not shown) after being demodulated; the RNC combines the data from the three channels, so as to improve quality of the uplink signal. Similarly, downlink signals are transmitted via the three NodeBs to the UE; the UE combines the signals from the three channels, so as to improve quality of the received signals and prevent data loss during the cross-cell handover. Such a signal combining technique is referred to as macro diversity, and the switching technique is referred to as cross-cell soft handover. 
     Because the uplink signal is transmitted from the UE to different cells at the uplink channel transmit power of the UE, and when the uplink channel transmit power of the UE is too high, the uplink signal of the UE may bring more interference with uplink data transmission of other UEs in the entire cell, and therefore results in degraded quality of data transmission from other UEs in the cell or even results in call drops. 
     In the conventional art, when a soft handover is carried out for a UE in a connected state, there is a need to establish connections between the UE and respective cells corresponding to overlap areas involved in the soft handover and to control the uplink power of the UE, so as to avoid any UE interference with each of the respective cells. Specifically, in the soft handover process, the UE detects downlink pilot signals from neighboring cells and reports the downlink pilot signals from the neighboring cells to the RNC; the RNC receives and judges the information. If it is determined from list of the downlink pilot signals from the neighboring cells reported by the UE that a cell meets a soft handover threshold, the RNC determines that a new radio link needs to be established in the new cell for the UE, and the RNC initiates a radio connection setup request to the NodeB in the cell, requesting the NodeB to allocate resources to the new radio connection to be established. When the NodeB receives the request, it judges whether there are available resources for the moment; if there are available resources, the request is accepted, and the RNC and the NodeB allocate resources required for the establishment of the connection to the UE, and establish the connection between the UE and the NodeB in the cell; or if the NodeB is accessed by many UEs at present and has no available resources, the request is rejected. In this case, the RNC refuses to establish a radio link in the new cell for the UE. If a radio connection is established successfully between the UE and the cell, the cell can control the uplink channel transmit power of the UE to be within a reasonable range by utilizing inner ring power control and outer ring power control by means of an uplink Transmit power Control (TPC) command or downlink power adjustment indication, so that the UE, when it is in the overlap area and under a soft handover, does not cause interference with the neighboring cells. 
     However, in practical applications, when the UE is in a soft handover state, the existing uplink transmit power control method in the conventional art may be unable to effectively avoid interference with the cells to which the overlap area involved in the soft handover belongs, and is not applicable to an LTE evolved network. 
     The inventor has found that the main reason for this situation lies in that: in order to control the uplink channel transmit power of the UE, a NodeB has to establish a radio connection to the UE first; however, due to limited uplink demodulation resources of the NodeB in the neighboring cell, some cells involved in the soft handover may be unable to establish a radio connection to the UE. In that case, the NodeB is unable to control the uplink channel transmit power of the UE, and therefore the uplink channel transmit power of the UE may be too high and cause interference with the cell, thereby resulting in degraded system performance of the cell and a risk of system instability. 
     Furthermore, in the LTE evolution process, the RNC function in the existing network is distributed to eNodeBs and nodes on higher layers (e.g., GW). In such a situation, the UE can only keep a radio connection to the NodeB in one cell  201  when the UE transmits data in any overlap area, as shown in  FIG. 2 , while the other cells  202  and  203  having the overlap area are unable to establish a radio connection to the UE by means of technique in the conventional art to control the uplink channel transmit power; therefore, the UE interference with the neighboring cells cannot be avoided. 
     SUMMARY OF THE INVENTION 
     The present invention provides a mobile communication system, a neighboring cell interference suppression method and a base station in the mobile communication system, which enables the base station to improve system stability and accuracy in fast dispatching. 
     A neighboring cell interference suppression method in a mobile communication system includes (1) configuring, in a non-serving radio link established for a UE, an uplink channel for estimation of contribution of the UE to uplink load in a cell and a downlink channel for control of transmit power of the UE; and (2) estimating the contribution of the UE to the uplink load in the cell in accordance with signals received through the uplink channel and controlling the transmit power of the UE by means of the downlink channel based on the estimation result. 
     A base station includes (1) a first channel establishing module, configured to establish, in a non-serving radio link established for a UE, an uplink channel for estimation of contribution of the UE to uplink load in a cell and a downlink channel for control of transmit power of the UE; (2) an estimate module, configured to estimate contribution of the UE to uplink load in the cell with signals received through the uplink channel established by the first channel establishing module; and (3) a control module, configured to control the transmit power of the UE by means of the downlink channel based on an estimation result provided by the estimating module. 
     A mobile communication system includes a UE and a base station, in which the base station includes (1) a first channel establishing module, configured to establish, in a non-serving radio link established for the UE, an uplink channel for estimation of contribution of a UE to uplink load in a cell and a downlink channel for control of transmit power of the UE; (2) an estimate module, configured to estimate the contribution of the UE to the uplink load in the cell based on signals received through the uplink channel established by the first channel establishing module; and (3) a control module, configured to control the transmit power of the UP by means of the downlink channel based on an estimation result provided by the estimating module. 
     In embodiments of the present invention, only a control plane connection is established for a UE in the non-serving radio link established for the UE by the base station, and the contribution of the UE to the uplink load in the cell is estimated by means of an uplink channel established for the UE, so that the contribution of the UE in the neighboring cell to the uplink load becomes predictable; and the transmit power of the UE can be controlled based on the estimation result by means of the downlink channel established for the UE, and thereby the interference from the neighboring cells to which the overlap area belongs can be suppressed effectively, and the system stability and accuracy in fast dispatching by a base station can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a connection between a UE in the overlap area and a NodeB, in a WCDMA network; 
         FIG. 2  is a schematic diagram of a connection between a UE in the overlap area and a NodeB, in an LTE evolved network; 
         FIG. 3  is a schematic diagram of a connection between a UE in the overlap area and a NodeB in a interference suppression method for suppressing neighboring cell interference in a mobile communication system according to the present invention; 
         FIG. 4  is a flow diagram of a interference suppression method for suppressing neighboring cell interference in a mobile communication system according to a first embodiment of the present invention; 
         FIG. 5  is a flow diagram of a interference suppression method for suppressing neighboring cell interference in a mobile communication system according to a second embodiment of the present invention; 
         FIG. 6  is a structural block diagram of a NodeB according to a third embodiment of the present invention; and 
         FIG. 7  is a structural block diagram of a NodeB according to a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereunder embodiments of the present invention are further detailed with reference to the accompanying drawings. 
     In an embodiment of the present invention, in an overlap area of neighboring cells, a non-serving radio link established by a NodeB for a UE only includes a control plane connection, the contribution of the UE to the uplink load of the cell is estimated by means of the control plane connection, and the transmit power of the UE is controlled by means of the control plane connection. 
     As shown in  FIG. 3 , the UE is in the overlap area of the first cell  31 , the second cell  32  and the third cell  33 , and establishes radio links to the NodeBs in the respective three cells. For the UE, the first cell  31  is a serving cell, and a serving radio link, which includes both uplink channel and downlink channel, is established between the UE and the first NodeB  311  in the first cell  31 ; for the UE, the second cell  32  and the third cell  33  are non-serving cells, and non-serving radio links, which only include an uplink channel and downlink channel in the control plane, are established respectively between the UE and the second NodeB  322  in the second cell  32  and between the UE and the third NodeB  333  in the third cell  33 . Take the second NodeB  322  as an example, in establishing the non-serving radio link, the second NodeB  322  only establishes an uplink channel that is designed for estimation of the contribution of the UE to the uplink load in the cell  2  and a downlink channel that is designed for control of the transmit power of the UE. The second NodeB  322  estimates the contribution of the UE to the uplink load in the cell  2  based on signals received through the uplink channel, and controls the transmit power of the UE through the downlink channel based on the estimation result. Therefore, while the resources required for establishment of the radio links are reduced, interference from the neighboring cells to which the overlap area belongs can be effectively suppressed, thus improving system stability and accuracy in fast dispatching by the NodeB. 
     Hereunder, the neighboring cell interference suppression method in a mobile communication system according to the first embodiment of the present invention is described. 
     As shown in  FIG. 4 : 
     In step  410 , when the NodeB receives a soft handover request from the UE, it establishes a non-serving radio link for the UE. 
     The non-serving radio link is a radio link that includes an Enhanced-Dedicated Channel (abbreviated as E-DCH). The NodeB only sets in the radio link an uplink channel (e.g., uplink DPCCH or uplink E-DPCCH) designed for estimation of the contribution of the UE to the uplink load in the cell, and a downlink channel (e.g., downlink E-RGCH, F-DPCH, or DPDCH) designed for control of the transmit power of the UE. In practical applications, the downlink channel that is used by a non-serving cell to control the transmit power of the UE is a downlink E-RGCH. Similarly, one of the F-DPCH and the DPDCH can be elected and established, depending on the actual capability of the NodeB. Because the non-serving radio link established by the NodeB for the UE only includes control plane connections, the NodeB can control the transmit power of the UE through the control plane connections and avoid interference with its subordinate cells, even if the E-DPDCH demodulation resources are used up. 
     In step  420 , the NodeB judges whether the quantity of currently used resources has exceeded a preset threshold; if not, the NodeB proceeds with step  430 ; or if yes, the NodeB goes to step  440  directly. 
     In step  430 , the NodeB sets both control channel and data channel in the radio link. 
     The NodeB sets both control channel and data channel in the radio link, including each of the control channels that are set in step  410  and the E-DPDCH for receiving uplink data, so as to make a full use of the demodulation resources for high-speed uplink data packets access and avoid resource waste. The specific method of setting the channels can be carried out with reference to the method for setting relevant channels in the Enhanced-DCH in the conventional art, and is not described further here. 
     In step  440 , the NodeB estimates the contribution of the UE to the uplink load in the cell based on the signals received through the DPCCH and the uplink E-DPCCH. 
     Specifically, the NodeB estimates an SIR DPCCH  of the uplink DPCCH based on the pilot frequency information of the uplink DPCCH, and the specific method thereof is the same as that in the conventional art. 
     The NodeB obtains the power control gain factor β E-DPDCH  of the uplink E-DPDCH relative to the uplink DPCCH, based on data transmission format signaling information of the uplink E-DPDCH indicated in the current uplink E-DPCCH and reference transmission format information configured for the network. The specific method thereof is the same as that in the conventional art. 
     Next, the NodeB calculates an SIR E-DPDCH  of the uplink E-DPDCH using the expression 
     
       
         
           
             
               
                 SIR 
                 
                   E 
                   - 
                   DPDCH 
                 
               
               = 
               
                 
                   SIR 
                   DPCCH 
                 
                 · 
                 
                   
                     ( 
                     
                       
                         β 
                         
                           E 
                           - 
                           DPDCH 
                         
                       
                       
                         β 
                         DPCCH 
                       
                     
                     ) 
                   
                   2 
                 
               
             
             , 
           
         
       
     
     based on the obtained SIR DPCCH  of the uplink DPCCH of the UE, the power control gain factor β E-DPDCH  of the uplink E-DPDCH relative to the uplink E-DPDCH, and the gain factor parameter β DPCCH  of the uplink DPCCH pre-configured in the network. 
     Next, the NodeB calculates the power control gain factor β E-DPCCH  of the uplink E-DPCCH relative to the uplink DPCCH using the expression 
     
       
         
           
             
               
                 β 
                 
                   E 
                   - 
                   DPCCH 
                 
               
               = 
               
                 
                   β 
                   DPCCH 
                 
                 · 
                 
                   10 
                   
                     ( 
                     
                       
                         Δ 
                         
                           E 
                           - 
                           DPCCH 
                         
                       
                       20 
                     
                     ) 
                   
                 
               
             
             , 
           
         
       
     
     based on the power deviation parameter Δ E-DPCCH  of the uplink E-DPCCH relative to the uplink DPCCH that is pre-configured in the radio network and the gain factor parameter β DPCCH  of the uplink DPCCH. The NodeB further obtains the SIR E-DPCCH  of the uplink E-DPCCH using the expression 
     
       
         
           
             
               
                 SIR 
                 
                   E 
                   - 
                   DPCCH 
                 
               
               = 
               
                 
                   SIR 
                   DPCCH 
                 
                 · 
                 
                   
                     ( 
                     
                       
                         β 
                         
                           E 
                           - 
                           DPCCH 
                         
                       
                       
                         β 
                         DPCCH 
                       
                     
                     ) 
                   
                   2 
                 
               
             
             , 
           
         
       
     
     based on the power control gain factor β E-DPCCH , the estimated SIR DPCCH  of the uplink DPCCH, and the gain factor β DPCCH  of the uplink DPCCH that is pre-configured in the network. 
     If the uplink data transmission channel of the UE only includes an uplink E-DPDCH, the NodeB obtains the contribution of the UE to the uplink load in the cell using the expression 
     
       
         
           
             
               
                 contribution_to 
                  
                 _uplink 
                  
                 _load 
               
               = 
               
                 
                   ( 
                   
                     
                       SIR 
                       DPCCH 
                     
                     + 
                     
                       SIR 
                       
                         E 
                         - 
                         DPCCH 
                       
                     
                     + 
                     
                       SIR 
                       
                         E 
                         - 
                         DPDCH 
                       
                     
                   
                   ) 
                 
                 
                   1 
                   + 
                   
                     ( 
                     
                       
                         SIR 
                         DPCCH 
                       
                       + 
                       
                         SIR 
                         
                           E 
                           - 
                           DPCCH 
                         
                       
                       + 
                       
                         SIR 
                         
                           E 
                           - 
                           DPDCH 
                         
                       
                     
                     ) 
                   
                 
               
             
             , 
           
         
       
     
     based on the calculated SIR DPCCH , SIR E-DPDCH , and SIR E-DPDCH  of the DPCCH, E-DPDCH, and E-DPCCH respectively. If the uplink data transmission channel of the UE includes an uplink E-DPDCH and an uplink DPDCH, the NodeB needs to calculate the SIR DPDCH  of the uplink DPDCH using the expression 
     
       
         
           
             
               
                 SIR 
                 DPDCH 
               
               = 
               
                 
                   SIR 
                   
                     E 
                     - 
                     DPCCH 
                   
                 
                 · 
                 
                   
                     ( 
                     
                       
                         β 
                         DPDCH 
                       
                       
                         β 
                         
                           E 
                           - 
                           DPCCH 
                         
                       
                     
                     ) 
                   
                   2 
                 
               
             
             , 
           
         
       
     
     based on the above calculated SIR E-DPCCH  of the E-DPCCH, the power control gain factor UE β E-DPDCH  of the uplink E-DPDCH relative to the uplink DPCCH, and the gain factor parameter β DPDCH  of the uplink DPDCH that is pre-configured in the network. Based on the SIR DPDCH , and the SIR DPCCH , SIR E-DPDCH , and SIR E-DPCCH  as calculated above, the NodeB obtains the contribution of the UE to the uplink load in the cell using the expression 
     
       
         
           
             
               Contribution_to 
                
               _uplink 
                
               _load 
             
             = 
             
               
                 
                   ( 
                   
                     
                       SIR 
                       DPCCH 
                     
                     + 
                     
                       SIR 
                       DPDCH 
                     
                     + 
                     
                       SIR 
                       
                         E 
                         - 
                         DPCCH 
                       
                     
                     + 
                     
                       SIR 
                       
                         E 
                         - 
                         DPDCH 
                       
                     
                   
                   ) 
                 
                 
                   1 
                   + 
                   
                     ( 
                     
                       
                         SIR 
                         DPCCH 
                       
                       + 
                       
                         SIR 
                         DPDCH 
                       
                       + 
                       
                         SIR 
                         
                           E 
                           - 
                           DPCCH 
                         
                       
                       + 
                       
                         SIR 
                         
                           E 
                           - 
                           DPDCH 
                         
                       
                     
                     ) 
                   
                 
               
               . 
             
           
         
       
     
     In step  450 , the NodeB controls the transmit power of the UE via the downlink E-RGCH, based on the estimation result of contribution of the UE to the uplink load in the cell. 
     Specifically, if the NodeB estimates that the UE interference with uplink load in the cell is too high, it sends a Relative Grant (RG) command via the downlink E-RGCH, to instruct the UE to decrease the uplink data transmission rate, thereby reducing the uplink data transmission interference with the cell. So there is no need to improve the transmit power of other UEs in the cell, and thus the system stability and stability of the subscriber data transmission can be ensured and the system capacity can be improved. Or if the NodeB estimates that the UE interference with the uplink load in the cell is not too high, the NodeB does not need to send a downlink E-RGCH indication message. 
     It is worthwhile to mention that: in the embodiment of the present invention, the established non-serving radio link may not include a channel for data transmission, in order to reduce resources required for the establishment of the radio link. Therefore, when the UE carries out a soft handover for uplink serving cell update, it needs to determine whether the radio link between the UE and the target cell only includes an uplink channel for estimation the contribution of the UE to the uplink load in the cell and a downlink channel for controlling the transmit power of the UE; if the radio link only includes such an uplink channel and downlink channel, an associated channel for transmitting data (e.g., an uplink E-DPDCH) is required to be added in the radio link before the soft handover is started, so as to ensure that the UE can communicate normally after it is switched to the target cell. 
     A neighboring cell interference suppression method in the mobile communication system according to the second embodiment of the present invention is essentially identical to the method according to the first embodiment. However, in point of the application environment, the first embodiment is mainly applied in a network that employs the uplink macro diversity technique, while the second embodiment is mainly applied in a network where the uplink macro diversity technique is cancelled. 
     In the LTE evolved network, the uplink macro diversity is canceled in the system architecture, i.e., in the network, a UE in the overlap area can only establish a data transmission plane connection to its serving cells. In view of this change, this embodiment enables a NodeB in a non-serving cell (also referred to as eNodeB) to control transmit power of UEs in the neighboring cells to which the overlap area belongs by only establishing a control plane connection between the UE and the NodeB, thereby avoiding interference with the local cell from the UEs in the neighboring cells to which the overlap area belongs. 
     Specifically, as shown in  FIG. 5 : 
     In step  510 , the network side determines, based on a neighboring cell measurement report from the UE, a NodeB which is required to establish a non-serving radio link for the UE, and instructs the NodeB to establish the non-serving radio link for the UE. 
     Then, in step  520 , the NodeB establishes a non-serving radio link for the UE, and only an uplink channel for estimation of the contribution of the UE to the uplink load in the cell and a downlink channel for control of the transmit power of the UE are set in the radio link. 
     Next, the process goes to step  530 , in which the NodeB estimates the contribution of the UE to the uplink load in the cell, based on a signal received through the uplink channel. 
     The specific estimation method is similar to that in the first embodiment, and is not described here. In this embodiment, because there is no need to establish an associated channel for data transmission between the non-serving NodeB and the UE, the non-serving NodeB still can accurately estimate interference with the local cell from UEs of the neighboring cells to which the overlap area belongs, by means of the established control plane connection to the UE, even if the uplink macro diversity technique is canceled from the system architecture. Because only the control plane connection is established between the non-serving NodeB and the UE, the resources in the subscriber plane (e.g., non-serving NodeB resources and Tub transmission, etc.) will not be occupied, and therefore the system performance can be improved and the system stability can be achieved with less hardware resource consumption. 
     Next, the process goes to step  540 , in which the  540  controls the transmit power of the UE by means of the downlink channel according to the estimation result. 
     The NodeB does not need to increase transmit power of other UEs in the cell, and therefore the system stability and subscriber data transmission stability can be ensured, and the system capacity can be improved. 
       FIG. 6  is a structural block diagram of a NodeB according to the third embodiment of the present invention. In addition to the basic modules in the conventional art, the NodeB in the third embodiment of the present invention further includes a first channel establishing module  610 , an estimating module  620 , a control module  630 , a first judge module  640  and a second channel establishing module  650 . 
     The first channel establishing module  610  is configured to establish a non-serving radio link for a UE, in which only an uplink channel for estimation of the contribution of the UE to the uplink load in the cell and a downlink channel for control of the transmit power of the UE are configured. 
     The estimating module  620  is configured to estimate the contribution of the UE to the uplink load in the cell based on a signal received through the uplink channel established by the first channel establishing module  610 . 
     The control module  630  is configured to control the transmit power of the UE via the downlink channel based on an estimation result of the estimating module  620 . 
     The first judge module  640  is configured to judge whether the radio link established between the UE and the target cell only includes the uplink channel for estimation of the contribution of the UE to the uplink load in the cell and the downlink channel for control of the transmit power of the UE. 
     The second channel establishing module  650  is configured to receive an indication from the first judge module  640  and add an associated channel for data transmission in the radio link. 
     The radio link is one that includes Enhanced-Dedicated Channels. The uplink channel includes an uplink Dedicated Physical Control Channel and an uplink Enhanced-Dedicated Physical Control Channel, and the downlink channel includes a downlink Relative Grant Channel, a downlink Fractional-Dedicated Physical Channel, or a downlink Dedicated Physical Channel. 
     Specifically, when the NodeB receives a switching request from the UE in the overlap area, it instructs the first channel establishing module  610  to establish a non-serving radio link for the UE. The first channel establishing module  610  only establishes an uplink channel for estimation of the contribution of the UE to the uplink load in the cell and a downlink channel for control of the transmit power of the UE. Next, the estimate module  620  estimates the contribution of the UE to the uplink load in the cell based on a signal received through the uplink channel established by the first channel establishing module  610 , and instructs the control module  630  of the estimation result. The control module  630  controls the transmit power of the UE via the downlink channel based on the estimation result provided by the estimating module  620 , and thereby the interference from the neighboring cells to which the overlap area belongs is effectively suppressed and the accuracy in fast dispatching by the NodeB is improved without increasing transmit power of other UEs in the cell, and the system stability and the subscriber data transmission rate stability can be ensured. 
     In addition, in the embodiments of the present invention, in order to reduce the resources required for establishment of the radio link, the established non-serving radio link doesn&#39;t include a channel for data transmission. Therefore, when the UE carries out a soft handover, it is required to judge by the first judging module  640  whether the radio link between the UE and the target cell only includes an uplink channel for estimation of the contribution of the UE to the uplink load in the cell and a downlink channel for control of the transmit power of the UE. If the radio link only includes the uplink channel and the downlink channel, the first judging module  640  instructs the second channel establishing module  650  to add in the radio link an associated channel for data transmission, so as to ensure that the UE can communicate normally after it is switched to the target cell. 
       FIG. 7  shows a structural block diagram of a NodeB according to the fourth embodiment of the present invention. In addition to the modules in the third embodiment, the fourth embodiment of the present invention further includes a second judge module  660  and a third channel establishing module  670 . 
     The second judge module  660  is configured to judge whether the quantity of resources currently used by the UE has exceeded a preset threshold; 
     The third channel establishing module  670  is configured to configure both control channel and data channel in the established non-serving radio link when the second judging module  660  determines that the quantity of resources currently used by the UE has not exceeded the preset threshold. 
     For other modules of the fourth embodiment of the present invention, please refer to the description of the third embodiment. These modules are not described further here. 
     According to embodiments of the present invention, when a NodeB establishes a non-serving radio link for the UE, only a control plane connection is established, and the contribution of the UE to the uplink load in the cell is estimated by means of the established uplink channel so that the contribution of UEs in the neighboring cells to the uplink load becomes predictable, and the transmit power of the UE can be controlled by means of the established downlink channel based on the estimation result, and thereby interference from the neighboring cells to which the overlap area belongs can be suppressed effectively, and the system stability and accuracy in fast dispatching by the NodeB can be improved. 
     If the non-serving radio link becomes a serving radio link during the handover, a channel for carrying data is added to the radio link, so as to ensure the UE can communicate normally after the UE is switched to the new serving radio link. 
     For the existing HSUPA system, when a NodeB receives a soft handover request from a UE in a neighboring cell, it establishes for the UE a non-serving radio link that only includes a control plane connection. Therefore, even if the E-DPDCH demodulation resources are used up, the contribution of the UE in the overlap area involved in the soft handover to the uplink load in the cell can be estimated accurately by means of the established control plane connection. If the uplink load of the UE in the overlap area involved in the soft handover is too high, the downlink control channel can be used to instruct the UE to reduce the uplink data transmission rate, without increasing the transmit power of the UE for which the radio link is established. The method therefore can ensure the system stability and the stability of subscriber data transmission rate, and improve the system capacity. 
     In addition, when the NodeB establishes a non-serving radio link for the UE, it can judge based on the present consumption situation of the E-DPDCH demodulation resources. If the free E-DPDCH demodulation resources are relatively less, only a control channel is established. If the free E-DPDCH demodulation resources are relatively more, an E-DPDCH for receiving uplink data can be established for the UE, so as to make full use of demodulation resources accessed by the uplink high-speed packet and avoid resource waste. 
     For the Enhanced-High-Speed Packet Access (E-HSPA) technique under research, even if the uplink macro diversity technique is canceled in the system architecture, the non-serving NodeB can still only establish a control plane connection to the UE upon the notification from the network side, so as to accurately estimate interference with the local cell from UEs in the neighboring cells to which the overlap area belongs, intervene and regulate the uplink transmit power of the UE by means of the downlink control channel, and attain the object of interference control. In addition, because only a control plane connection is established, the resources in the subscriber plane (e.g., NodeB resources and Tub transmission resources, etc.) are not occupied, and therefore the system performance can be improved and the system stability can be achieved with less hardware resource consumption. 
     While the present invention has been illustrated and described with reference to some exemplary embodiments, the present invention is not limited to such embodiments. Those skilled in the art should appreciate that various variations and modifications can be made without departing from the spirit and scope of the present invention as defined by the accompanying claims.