Patent Publication Number: US-2015085753-A1

Title: Small cell coverage adjusting method, device, and system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2012/076653, filed on Jun. 8, 2012, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the field of communication technologies, and in particular, to a small cell coverage adjusting method, device, and system. 
     BACKGROUND 
     Currently, small cells (Small Cell) are commonly deployed in many macro cells (Macro Cell), and a small cell can provide seamless coverage to some blind spot areas and hotspot areas of a macro cell, which can not only greatly improve the system capacity, but also help a macro cell offload services. A network jointly deployed by macro cells and small cells is also called a heterogeneous network (HetNet). 
     In a heterogeneous network, macro cells and small cells may be intra-frequency deployed or may also be inter-frequency deployed, and in particular, when the macro cells and small cells are intra-frequency deployed, the coverage range of the macro cells and the coverage range of the small cells are overlapped, which causes the problem of intra-frequency interference. The coverage range of a small cell may overlap with the coverage range of multiple macro cells, or may also overlap with the coverage range of only one macro cell. In practical applications, if more user equipments (UE) accessing a small cell exist, more throughput may be obtained by the small cell, and at the same time, a better result of offloading services may be provided for a macro cell. However, the transmit power of a small cell is much less than the transmit power of a macro cell, and a UE detects the signal quality of small cells (mainly the pilot signal quality of the small cells) to select a small cell to access and accept services of the small cell, so the number of UEs accessing the small cell is small, and the coverage range of the small cell is small as well. Therefore, in the prior art, when a UE detects the signal quality of a small cell, in general, a range extension (RE) value is added based on the signal quality of the small cell to make the UE access the small cell, thereby enlarging the number of UEs accessing the small cell, and extending the coverage range of the small cell. 
     However, the above RE value is generally fixedly preset on the small cell, which causes that the small cell cannot offload services on the macro cell better. Meanwhile, the small cell blindly expanding the coverage may also increase the intra-frequency interference to the macro cell. 
     SUMMARY 
     In a plurality of aspects, the present invention provides a small cell coverage adjusting method, device, and system, which are used to dynamically adjust the coverage of a small cell, so that the small cell can offload services on a macro cell better, and decrease intra-frequency interference caused by the coverage of the small cell to the macro cell. 
     In one aspect, the present invention provides a small cell coverage adjusting method, which includes: determining whether a load of a macro cell meets a coverage parameter value adjusting condition of a small cell; and if the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, sending a request message carrying a coverage parameter adjusting value to the small cell, so that after receiving the coverage parameter adjusting value, the small cell adjusts a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     In another aspect, the present invention provides a small cell coverage adjusting method, which includes: receiving a request message carrying a coverage parameter adjusting value from a macro cell; and determining whether a small cell accepts the coverage parameter adjusting value, and if yes, thereby adjusting a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     Correspondingly, in one aspect, the present invention provides a small cell coverage adjusting device, which includes: a determining unit, configured to determine whether a load of a macro cell meets a coverage parameter value adjusting condition of a small cell; and an adjusting unit, configured to: when the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, send a request message carrying a coverage parameter adjusting value to the small cell, so that after receiving the coverage parameter adjusting value, the small cell adjusts a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     Correspondingly, in another aspect, the present invention provides a small cell coverage adjusting device, which includes: a transceiver unit, configured to receive a request message carrying a coverage parameter adjusting value from a macro cell; a determining unit, configured to determine whether a small cell accepts the coverage parameter adjusting value; and an adjusting unit, configured to: when a determining result of the determining unit is yes, adjust a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     Correspondingly, in one aspect, the present invention provides a small cell coverage adjusting system, which includes a first small cell coverage adjusting device and a second small cell coverage adjusting device, where: the first small cell coverage adjusting device is configured to determine whether a load of a macro cell meets a coverage parameter value adjusting condition of a small cell, and if the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, send a request message carrying a coverage parameter adjusting value to the second small cell coverage adjusting device; and the second small cell coverage adjusting device is configured to receive the request message carrying the coverage parameter adjusting value from the first small cell coverage adjusting device, and determine whether the small cell accepts the coverage parameter adjusting value, and if yes, adjust a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     In the technical solutions described above, a coverage parameter of the small cell can be dynamically adjusted according to a current condition of the macro cell and the small cell, so that the small cell can offload services on the macro cell better; and further, the small cell blindly expanding the coverage is avoided to decrease the intra-frequency interference caused by the coverage of the small cell to the macro cell. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       To make the technical solutions of the embodiments of the present invention clearer, the following briefly describes the accompanying drawings required for describing the embodiments. Evidently, the accompanying drawings in the following description show merely some of the embodiments of the present invention, and a person of ordinary skill in the art may obtain other drawings based on these accompanying drawings without creative efforts. 
         FIG. 1  is a flow chart of a small cell coverage adjusting method according to an embodiment of the present invention; 
         FIG. 2   a - FIG. 2   c  are three different architecture diagrams of a macro cell and small cell deployment according to an embodiment of the present invention; 
         FIG. 3  is a flow chart of another small cell coverage adjusting method according to an embodiment of the present invention; 
         FIG. 4  is a flow chart of another small cell coverage adjusting method according to an embodiment of the present invention; 
         FIG. 5  is a flow chart of still another small cell coverage adjusting method according to an embodiment of the present invention; 
         FIG. 6  is a structural diagram of a micro cell coverage adjusting device according to an embodiment of the present invention; 
         FIG. 7  is a structural diagram of a small cell coverage adjusting device according to an embodiment of the present invention; 
         FIG. 8  is a structural diagram of another small cell coverage adjusting device according to an embodiment of the present invention; and 
         FIG. 9  is a structural diagram of a small cell coverage adjusting system according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following clearly describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention. 
     Technologies described in this document may be used in various communication systems, for example, current 2G and 3G communication systems and a next-generation communication system, for example, a Global System for Mobile Communications (GSM) system, a Code Division Multiple Access (CDMA, Code Division Multiple Access) system, a Time Division Multiple Access (TDMA) system, a Wideband Code Division Multiple Access (WCDMA) system, a Frequency Division Multiple Access (FDMA) system, an orthogonal frequency-division multiple access (OFDMA) system, a single-carrier FDMA (SC-FDMA) system, a general packet radio service (GPRS) system, a Long Term Evolution (LTE) system, and other communication systems of this type. 
     The present document describes various aspects with reference to a user equipment and/or a base station and/or a base station controller. 
     The user equipment may be a wireless terminal or a wired terminal, where the wireless terminal may refer to a device providing voice and/or data connectivity for a user, a handheld device with a wireless connection function, or other processing devices connected to a wireless modem. The wireless terminal may communicate with one or more core networks through a wireless access network (for example, RAN, Radio Access Network), and the wireless terminal may be a mobile terminal, for example, a mobile phone (also called a “cellular” phone), or a computer with a mobile terminal, for example, a portable, pocket-sized, handheld, computer-build-in, or vehicle-mounted mobile apparatus, which exchanges language and/or data with the wireless access network. For example, it may be a device such as a personal communication service (PCS) phone, a cordless telephone set, a Session Initiation Protocol (SIP) phone, a wireless local loop (WLL) station, and a personal digital assistant (PDA). The wireless terminal may also be called a system, a subscriber unit, a subscriber station, a mobile station, a mobile terminal, a remote station, an access point, a remote terminal, an access terminal, a user terminal, a user agent, a user device, or a user equipment. 
     The base station (for example, an access point) may refer to a device in communication with a wireless terminal through one or more sectors at an air interface in an access network. The base station may be configured to mutually convert a received air frame and an IP packet and serve as a router between the wireless terminal and a rest portion of the access network, where the rest portion of the access network may include an Internet protocol (IP) network. The base station may further coordinate attribute management of the air interface. For example, the base station may be a base station (BTS) in the GSM or the CDMA, or may also be a base station (NodeB) in the WCDMA, or may further be an evolutional base station (NodeB, eNB, or e-NodeB, evolutional Node B) in the LTE, which is not limited in the present invention. 
     The base station controller may be a base station controller (BSC) in the GSM or CDMA, or may also be a radio network controller (RNC) in the WCDMA, which is not limited in the present invention. 
     In addition, the terms “system” and “network” in this document can always be exchanged for use in this document. The term “and/or” in this document merely describes an association between associated objects, and indicates that three relationships may exist, for example, A and/or B may indicate three situations: only A exists, A and B exist at the same time, and only B exists. In addition, the symbol “/” in this document usually represents that associated objects before and after the symbol are in an “or” relationship. 
     Embodiments of the present invention provide a small cell coverage adjusting method, device, and system, which can dynamically adjust a coverage parameter of a small cell according to a current condition of a macro cell and the small cell, so that the small cell may offload services on the macro cell better, and decrease intra-frequency interference caused by the coverage of the small cell to the macro cell. The embodiments of the present invention are described in detail as follows: 
     Referring to  FIG. 1 ,  FIG. 1  is a flow chart of a small cell coverage adjusting method according to an embodiment of the present invention. As shown in  FIG. 1 , the small cell coverage adjusting method may be as follows: 
       101 : Determine whether a load of a macro cell meets a coverage parameter value adjusting condition of a small cell. 
     For example, a coverage parameter value of the small cell includes an RE value of the small cell or a pilot power value of the small cell; and in another embodiment of the present invention, the coverage parameter value of the small cell may include a pilot power bias value of the small cell, that is, a percentage of the pilot power of the small cell to the total transmit power of the small cell. 
       102 : If the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, send a request message carrying a coverage parameter adjusting value to the small cell, so that after receiving the coverage parameter adjusting value, the small cell adjusts a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     In the embodiment of the present invention, as shown in  FIG. 2   a , a base station of a macro cell may be managed by a radio network controller (Radio Network Controller, RNC) of the macro cell, and a base station of a small cell may be managed by an RNC of the small cell; alternatively, as shown in  FIG. 2   b , a base station of a small cell may also complete exchanging information with an RNC of a macro cell through a base station gateway of the small cell; alternatively, as shown in  FIG. 2   c , a base station of a small cell and a base station of a macro cell are managed by the same RNC (that is, an RNC of the base station of the small cell or an RNC of the base station of the macro cell). In particular, when the base station of the small cell completes exchanging information with the RNC of the macro cell through the base station gateway of the small cell, the base station of the small cell may complete RNC functions of the small cell, and at this time, the base station gateway of a small cell provides a convergence function. In practical applications, as shown in  FIG. 2   a , if the macro cell is managed by the RNC of the macro cell, and the small cell is managed by the RNC of the small cell, the base station of the macro cell may exchange information with the RNC of the macro cell through an Iub interface, the base station of the small cell may also exchange information with the RNC of the small cell through the Iub interface, and an RNC of a macro base station may exchange information with the RNC of the small cell through an Iur interface. As shown in  FIG. 2   b , if the base station of the macro cell is managed by the RNC of the macro cell, and the base station of the small cell exchanges information through the base station gateway of the small cell, the base station of the macro cell may exchange information with the RNC of the macro cell through the Iub interface, the base station of the small cell may exchange information with the base station gateway of the small cell through an Tub interface or an Iurh interface, and the RNC of the macro base station may exchange information with the base station gateway of the small cell through the lur interface. 
     Therefore, in step  101 , whether the load of the macro cell meets the coverage parameter value adjusting condition of the small cell may be determined by the RNC of the macro cell, and in step  102 , if the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, the RNC of the macro cell may send the request message carrying the coverage parameter adjusting value to the RNC of the small cell or forwards the request message to the base station of the small cell through the base station gateway of the small cell, so that after determining to accept the coverage parameter adjusting value, the RNC of the small cell or the base station of the small cell adjusts the current coverage parameter value of the small cell according to the coverage parameter adjusting value. For the purpose of convenient description, the embodiments of the present invention take the base station of the macro cell being managed by the RNC of the macro cell and the base station of the small cell being managed by the RNC of the small cell as examples to introduce the small cell coverage adjusting method provided in the embodiments of the present invention. 
     As an optional implementation manner, the small cell coverage adjusting method shown in  FIG. 1  may be triggered by step 1) and step 2). 
     1) The macro cell (that is, the RNC of the macro cell) receives a coverage parameters report message from the small cell (that is, the RNC of the small cell), where, the coverage parameters report message at least carries an identifier of the small cell and the current coverage parameter value of the small cell. 
     As an optional implementation manner, the coverage parameter report message sent by the small cell (that is, the RNC of the small cell) may be actively sent by the small cell (that is, the RNC of the small cell) to the macro cell (that is, the RNC of the macro cell) when a coverage parameter of the small cell changes. 
     2) If the current coverage parameter value of the small cell is within an adjustable range, the macro cell (that is, the RNC of the macro cell) selects the small cell as a small cell whose coverage parameter is to be adjusted. 
     For example, if the current coverage parameter value of the small cell is larger than a maximum threshold, the macro cell (that is, the RNC of the macro cell) does not select the small cell as the small cell whose coverage parameter is to be adjusted; reversely, if the current coverage parameter value of the small cell is smaller than a minimum threshold, the macro cell (that is, the RNC of the macro cell) does not select the small cell as the small cell whose coverage parameter is to be adjusted either. That is to say, when the current coverage parameter value of the small cell is between the maximum threshold and the minimum threshold, the current coverage parameter value of the small cell is thought to be within the adjustable range. 
     On the basis of step 1) and step 2), in step  102 , the sending a request message carrying a coverage parameter adjusting value to the small cell, so that after determining to accept the coverage parameter adjusting value, the small cell adjusts a current coverage parameter value of the small cell according to the coverage parameter adjusting value may be that: The macro cell (that is, the RNC of the macro cell) sends the request message carrying the coverage parameter adjusting value to the small cell whose coverage parameter is to be adjusted, so that after determining to accept the coverage parameter adjusting value, the small cell whose coverage parameter is to be adjusted adjusts, according to the coverage parameter adjusting value, a current coverage parameter value of the small cell whose coverage parameter is to be adjusted. 
     As an optional implementation manner, in step 1), the coverage parameter report message sent by the small cell (that is, the RNC of the small cell) may further carry location information of the small cell relative to the macro cell, so that the coverage parameter adjusting value carried by the request message sent by the macro cell (that is, the RNC of the macro cell) matches the location information. For example, when the location information is large (that is, a distance between the base station of the small cell and the base station of the macro cell is larger than or equal to a first distance threshold), the coverage parameter adjusting value carried by the request message sent by the macro cell (that is, the RNC of the macro cell) is larger than or equal to a first coverage parameter threshold, thereby effectively extending the coverage of the small cell, so that the small cell may help the macro cell offload services better; or when the location information is small (that is, a distance between the base station of the small cell and the base station of the macro cell is smaller than or equal to a second distance threshold), the coverage parameter adjusting value carried by the request message sent by the macro cell (that is, the RNC of the macro cell) is smaller than or equal to a second coverage parameter threshold, thereby effectively controlling the coverage of the small cell, reducing intra-frequency interference between the small cell and the macro cell; where, the second distance threshold is smaller than the first distance threshold, and the first coverage parameter threshold is larger than the second coverage parameter threshold. 
     As another optional implementation manner, the small cell coverage adjusting method shown in  FIG. 1  may be periodically triggered by the macro cell (that is, the RNC of the macro cell), or when a coverage parameter (that is, load information and so on) of the macro cell changes, be triggered by the small cell (that is, the RNC of the small cell), and in this case, the small cell (that is, the RNC of the small cell) does not need to send the coverage parameters report message. 
     As an optional implementation manner, in step  101 , the determining whether a load of a macro cell meets a coverage parameter value adjusting condition of a small cell may specifically include: determining, by the macro cell (that is, the RNC of the macro cell), whether an uplink load and a downlink load of the macro cell are both lower than respective preset thresholds, and if yes, determining that the load of the macro cell meets the coverage parameter value adjusting condition of the small cell; in this case, the coverage parameter adjusting value carried by the request message in step  102  may be smaller than the current coverage parameter value of the small cell, so that the coverage of the small cell may be reduced when the load of the macro cell is low. 
     As another optional implementation manner, in step  101 , the determining whether a load of a macro cell meets a coverage parameter value adjusting condition of a small cell may specifically include: determining, by the macro cell (that is, the RNC of the macro cell), whether an uplink load or a downlink load of the macro cell is either higher than a respective preset threshold, and if yes, determining that the load of the macro cell meets the coverage parameter value adjusting condition of the small cell; in this case, the coverage parameter adjusting value carried by the request message in step  102  may be larger than the current coverage parameter value of the small cell, so that the coverage of the small cell may be extended when the load of the macro cell is high. 
     As an optional implementation manner, the small cell coverage adjusting method shown in  FIG. 1  may further include following steps: The macro cell (that is, the RNC of the macro cell) receives a response message sent by the small cell, where, the response message carries the adjusted coverage parameter value of the small cell. In particular, when the coverage parameter value of the small cell is an RE value of the small cell, after the small cell completes adjusting the RE value, it needs to send the adjusted RE value of the small cell to the macro cell (that is, the RNC of the macro cell) through a response message, so that the macro cell (that is, the RNC of the macro cell) applies the RE value to the small cell. 
     In an embodiment, when the coverage parameter value of the small cell is a pilot power value of the small cell, after the small cell completes adjusting the pilot power value, it may not send a coverage control response message to the macro cell (that is, the RNC of the macro cell). 
     In the small cell coverage adjusting method shown in  FIG. 1 , the coverage parameter of the small cell can be dynamically adjusted according to a current condition of the macro cell and the small cell, so that the small cell can offload services on the macro cell better; and meanwhile, the small cell blindly expanding the coverage is avoided to decrease the intra-frequency interference caused by the coverage of the small cell to the macro cell. 
     Referring to  FIG. 3 ,  FIG. 3  is a flow chart of a small cell coverage adjusting method according to an embodiment of the present invention. In  FIG. 3 , a coverage parameter of a small cell being an RE value of the small cell is taken as an example to introduce the small cell coverage adjusting method provided in the embodiment of the present invention. As shown in  FIG. 3 , the small cell coverage adjusting method may include following steps. 
       301 : A macro cell (that is, an RNC of the macro cell) receives a coverage parameters report (Coverage Parameters Report) message from a small cell (that is, an RNC of the small cell), where, the coverage parameters report (Coverage Parameters Report) message at least carries an identifier of the small cell and a current RE value of the small cell. 
     As an optional implementation manner, the coverage parameters report (Coverage Parameters Report) message sent by the small cell (that is, the RNC of the small cell) may further carry location information of the small cell relative to the macro cell, the transmit power of the small cell, and so on. In practical applications, the location information of the small cell relative to the macro cell may be divided into three categories: far, middle, and near. 
       302 : If the current RE value of the small cell is within an adjustable range, the macro cell (that is, the RNC of the macro cell) selects the small cell as a small cell whose coverage parameter is to be adjusted; and configures an RE adjusting value to the small cell according to a load of the macro cell. 
     The small cell configures the RE adjusting value of the micro cell according to the load of the macro cell, where, if the load of the macro cell is low, the macro cell (that is, the RNC of the macro cell) may configure an RE adjusting value that is smaller than the current RE value of the small cell, so as to reduce the coverage of the small cell; or if the load of the macro cell is high, the macro cell (that is, the RNC of the macro cell) may configure an RE adjusting value that is larger than the current RE value of the small cell, so as to extend the coverage of the small cell. 
     In an embodiment, if an uplink load of the macro cell is lower than a threshold (UL _load_low), and a downlink load of the macro cell is lower than a threshold (DL_load_low), the macro cell (that is, the RNC of the macro cell) may configure an RE adjusting value that is lower than the current RE value of the small cell to the small cell, so as to reduce the coverage of the small cell; meanwhile if an uplink load of the macro cell is higher than a threshold (UL_load_high), or a downlink load of the macro cell is higher than a threshold (DL_load_high), the macro cell (that is, the RNC of the macro cell) may configure an RE adjusting value that is larger than the current RE value of the small cell to the small cell, so as to extend the coverage of the small cell. 
     In an embodiment, if the coverage parameters report message (Coverage Parameters Report) sent by the small cell (that is, the RNC of the small cell) further carries location information of the small cell relative to the macro cell, the RE adjusting value configured by the macro cell (that is, the RNC of the macro cell) to the small cell may match the location information. 
       303 : The macro cell (that is, the RNC of the macro cell) sends a request message carrying the RE adjusting value, for example, the coverage control request (Coverage Control Request) message to the small cell, so that after determining to accept a coverage parameter adjusting value, the small cell adjusts the current RE value of the small cell according to the RE adjusting value. 
     In an embodiment, the macro cell (that is, the RNC of the macro cell) may also send one or more RE adjusting values to the small cell through the coverage control request (Coverage Control Request) message for determining, and finally select a proper RE adjusting value. Furthermore, the coverage control request (Coverage Control Request) message may also carry the time of adjusting the RE value, the step length of adjusting the RE), or the like, which is not limited in the embodiment of the present invention. 
     The embodiments of the present invention will describe the processes of the small cell determining whether to accept the RE adjusting value in detail with reference to specific embodiments, which will not be described herein. 
       304 : The macro cell (that is, the RNC of the macro cell) receives a response message sent by the small cell, for example, the coverage control response message Coverage Control Response, where, the coverage control response message Coverage Control Response carries the adjusted RE value of the small cell; and the macro cell (that is, the RNC of the macro cell) applies the RE value to the small cell. 
     In the small cell coverage adjusting method shown in  FIG. 3 , the macro cell (that is, the RNC of the macro cell) can dynamically adjust a coverage parameter of the small cell according to a current condition of the macro cell and the small cell, so that the small cell can offload services on the macro cell better; and meanwhile, the small cell blindly expanding the coverage is avoided to decrease intra-frequency interference caused by the coverage of the small cell to the macro cell. 
     Further referring to  FIG. 4 ,  FIG. 4  is a flow chart of a small cell coverage adjusting method according to an embodiment of the present invention. As shown in  FIG. 4 , the small cell coverage adjusting method may include following steps. 
       401 : Receive a request message carrying a coverage parameter adjusting value from a macro cell (that is, an RNC of the macro cell); where, the request message is sent after the macro cell (that is, the RNC of the macro cell) determines that a load of the macro cell meets a coverage parameter value adjusting condition of a small cell, and a coverage parameter value of the small cell includes an RE value of the small cell or a pilot power value or a pilot power bias value of the small cell. 
       402 , Determine whether the small cell accepts the coverage parameter adjusting value, and if yes, adjust a current coverage parameter value of the small cell according to the coverage parameter adjusting value, 
     In an embodiment, when a base station of the small cell is managed by an RNC of the small cell, the RNC of the small cell may execute step  401  and step  402 ; when the base station of the small cell exchanges information through a base station gateway of the small cell, the base station gateway of the small cell may execute step  401 , and the base station of the small cell executes step  402 , which is not limited in the embodiment of the present invention. 
     As an optional implementation manner, before step  401 , the small cell coverage adjusting method shown in  FIG. 4  may further include following steps: 
     The RNC or the base station gateway of the small cell sends a coverage parameters report message at least carrying an identifier of the small cell and the current coverage parameter value of the small cell to the macro cell (that is, the RNC of the macro cell), so that when the macro cell (that is, the RNC of the macro cell) determines the current coverage parameter value of the small cell is within an adjustable range, the macro cell selects the small cell as a small cell whose coverage parameter is to be adjusted, and sends the request message carrying the coverage parameter adjusting value. That is to say, in the small cell coverage adjusting method shown in  FIG. 4 , the RNC or the base station of the small cell may send the coverage parameters report message at least carrying the identifier of the small cell and the current coverage parameter value of the small cell to the macro cell (that is, the RNC of the macro cell), and trigger the macro cell (that is, the RNC of the macro cell) to execute step  101  and step  102 . 
     As an optional implementation manner, the determining whether the small cell accepts the coverage parameter adjusting value in step  402  may be detailed as follows: 
     If the coverage parameter adjusting value is higher than the current coverage parameter value of the small cell, that is to say, the macro cell (that is, the RNC of the macro cell) hopes to extend the coverage of the small cell, the RNC of the small cell or the base station of the small cell may determine whether capability information of the small cell is smaller than a preset threshold, and if yes, the RNC of the small cell or the base station of the small cell may determine that the small cell accepts the coverage parameter adjusting value; or if no, the RNC of the small cell or the base station of the small cell may determine that the small cell does not accept the coverage parameter adjusting value. 
     The capability information of the small cell may include the number of accessed users of the small cell, the resource usage of the small cell, and one or more pieces of high speed downlink packet access (High Speed Downlink Packet Access, HSDPA) schedule timeslot duty cycle information. For example, when all above values are smaller than corresponding specific preset thresholds, the RNC of the small cell or the base station of the small cell may determine that the small cell accepts the coverage parameter adjusting value; reversely, when a certain value is larger than a corresponding specific preset threshold, the RNC of the small cell or the base station of the small cell may determine that the small cell does not accept the coverage parameter adjusting value. In this case, the RNC of the small cell or the base station of the small cell may choose to properly reduce a current coverage parameter of the small cell. 
     As an optional implementation manner, the determining whether the small cell accepts the coverage parameter adjusting value in step  402  may be detailed as follows: 
     If the coverage parameter adjusting value is lower than the current coverage parameter value of the small cell, that is to say, the macro cell (that is, the RNC of the macro cell) hopes to reduce the coverage of the small cell, the RNC of the small cell or the base station of the small cell may determine that the small cell accepts the coverage parameter adjusting value. 
     In an embodiment, the RNC or the base station of the small cell may receive request messages carrying the coverage parameter adjusting value from multiple macro cells (including intra-frequency or inter-frequency macro cells), and when the coverage parameter adjusting values sent by the multiple macro cells are all accepted by the small cell, the RNC of the small cell or the base station of the small cell may select an acceptable largest coverage parameter adjusting value according to capability information of the small cell, so as to help the macro cell implement the service offloading better. 
     In practical applications, when the RNC of the small cell or the base station of the small cell receives request messages carrying the coverage parameter adjusting value from intra-frequency or inter-frequency macro cells, the RNC of the small cell or the base station of the small cell may preferentially meet the requirements of the intra-frequency macro cells. 
     In particular, when the coverage parameter value of the small cell is a pilot power value or a pilot power bias value of the small cell, by configuring the pilot power value or the bias value of the small cell to zero, the macro cell may implement a function of disabling the small cell, so as to achieve the objectives of energy saving and completely avoiding interference. 
     In an embodiment, when the capability information of the small cell includes the HSDPA schedule timeslot duty cycle information, and the small cell is managed by the RNC of the small cell, or the small cell and the macro cell are managed by the same RNC, the base station of the small cell may send the HSDPA schedule timeslot duty cycle information of the small cell within a period of statistic time to the RNC of the small cell. As shown in  FIG. 5 , a base station of the small cell Pico may send a capability information request message to the RNC of the small cell through an Iub interface, where, the capability information request message may carry the HSDPA schedule timeslot duty cycle information of the small cell; and correspondingly, after the RNC of the small cell obtains the HSDPA schedule timeslot duty cycle information of the small cell, the RNC may send a capability information response message to the base station of the small cell Pico. 
     In an embodiment, when the capability information of the small cell includes the HSDPA schedule timeslot duty cycle information, and the base station of the small cell exchanges information through the base station gateway of the small cell, the base station of the small cell Pico does not need to send the HSDPA schedule timeslot duty cycle information of the small cell to the base station gateway of the small cell, because the base station of the small cell has the capability to automatically get the HSDPA schedule timeslot duty cycle information of the small cell. 
     As an optional implementation manner, in the small cell coverage adjusting method shown in  FIG. 4 , after the RNC of the small cell or the base station of the small cell adjusts the current coverage parameter value of the small cell according to the coverage parameter adjusting value, the RNC of the small cell or the base station of the small cell may send a response message to the macro cell (that is, the RNC of the macro cell) through the base station gateway, where, the response message carries the adjusted coverage parameter value of the small cell. In particular, when the coverage parameter value of the small cell is the RE value of the small cell, after the RNC of the small cell or the base station of the small cell completes adjusting the RE value of the small cell and applies the RE value, the RNC of the small cell or the base station of the small cell needs to send the adjusted RE value of the small cell to the macro cell (that is, the RNC of the macro cell) through a response message, so that the macro cell (that is, the RNC of the macro cell) applies the RE value. 
     In an embodiment, when the coverage parameter value of the small cell is the pilot power value or the pilot power bias value of the small cell, after the RNC of the small cell or the base station of the small cell completes adjusting the pilot power value of the small cell, it may not send a response message to the macro cell (that is, the RNC of the macro cell). 
     In view of the above, in the small cell coverage adjusting method shown in  FIG. 4 , a coverage parameter of the small cell can be dynamically adjusted according to a current condition of the macro cell and the small cell, so that the small cell can offload services on the macro cell better; and meanwhile, the small cell blindly expanding the coverage is avoided to decrease intra-frequency interference caused by the coverage of the small cell to the macro cell. 
     It should be noted that, the macro cell in the above embodiment may also be a small cell, that is, when own capability or a load of a small cell has been changed, the small cell may also initiate coverage coordination processes to a certain macro cell or another small cell, and coordinates its own coverage parameter value or a coverage parameter value of another small cell through a request message. 
     Referring to  FIG. 6 ,  FIG. 6  is a structural diagram of a small cell coverage adjusting device according to an embodiment of the present invention. The small cell coverage adjusting device shown in  FIG. 6  may serve as an independent device to provide services for a macro cell, may also be an added part of an RNC of a macro cell to provide services for the macro cell, or be an RNC of a macro cell. As shown in  FIG. 6 , the small cell coverage adjusting device may include a determining unit  601  and an adjusting unit  602 . 
     The determining unit  601  is configured to determine whether a load of a macro cell meets a coverage parameter value adjusting condition of a small cell, where, the coverage parameter value of the small cell includes an RE value of the small cell or a pilot power value of the small cell; and the adjusting unit  602  is configured to: when the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, send a request message carrying a coverage parameter adjusting value to the small cell, so that after receiving the coverage parameter adjusting value, the small cell adjusts a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     Further referring to  FIG. 7 ,  FIG. 7  is another structural diagram of a small cell coverage adjusting device optimized based on the small cell coverage adjusting device shown in  FIG. 6  according to an embodiment of the present invention. Compared with the small cell coverage adjusting device shown in  FIG. 6 , the small cell coverage adjusting device shown in  FIG. 7  may further include a receiving unit  603  and a selecting unit  604 . 
     The receiving unit  603  is configured to receive a coverage parameters report message sent by the small cell, where, the coverage parameters report message at least carries an identifier of the small cell and the current coverage parameter value of the small cell; and the selecting unit  604  is configured to: when the current coverage parameter value of the small cell carried by the coverage parameters report message is within an adjustable range, select the small cell as a small cell whose coverage parameter is to be adjusted. Correspondingly, the adjusting unit  602  is specifically configured to: when the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, send the request message carrying the coverage parameter adjusting value to the small cell whose coverage parameter is to be adjusted, so that after determining to accept the coverage parameter adjusting value, the small cell whose coverage parameter is to be adjusted adjusts, according to the coverage parameter adjusting value, a current coverage parameter value of the small cell whose coverage parameter is to be adjusted. 
     As an optional implementation manner, the above coverage parameters report message may further carry location information of the small cell relative to the macro cell, so that the coverage parameter adjusting value carried by a coverage control request message sent by the adjusting unit  602  matches the location information. 
     As an optional implementation manner, in the small cell coverage adjusting devices shown in  FIG. 6  and  FIG. 7 , the determining unit  601  is specifically configured to determine whether an uplink load and a downlink load of the macro cell are both lower than respective preset thresholds, and if yes, determine that the load of the macro cell meets the coverage parameter value adjusting condition of the small cell; in this case, the coverage parameter adjusting value carried by the coverage control request message is smaller than the current coverage parameter value of the small cell. 
     As an optional implementation manner, in the small cell coverage adjusting devices shown in  FIG. 6  and  FIG. 7 , the determining unit  601  is specifically configured to determine whether an uplink load or a downlink load of the macro cell is either higher than a respective preset threshold, and if yes, determine that the load of the macro cell meets the coverage parameter value adjusting condition of the small cell; where, the coverage parameter adjusting value carried by the coverage control request message is larger than the current coverage parameter value of the small cell. 
     As an optional implementation manner, in the small cell coverage adjusting device shown in  FIG. 7 , the receiving unit  603  is further configured to receive a response message sent by the small cell, where, the response message carries the adjusted coverage parameter value of the small cell. 
     The small cell coverage adjusting devices shown in  FIG. 6  and  FIG. 7  can dynamically adjust a coverage parameter of the small cell according to a current condition of the macro cell and the small cell, so that the small cell can offload services on the macro cell better; and meanwhile, the small cell blindly expanding the coverage is avoided, so as to decrease intra-frequency interference caused by the coverage of the small cell to the macro cell. 
     Referring to  FIG. 8 ,  FIG. 8  is a structural diagram of a small cell coverage adjusting device according to an embodiment of the present invention. The small cell coverage adjusting device shown in  FIG. 8  may serve as an independent device to provide services for a small cell, or may be an added part of an RNC of a small cell or a base station gateway of a small cell to provide services for a macro cell, or may be an RNC of a small cell or a base station gateway of a small cell. As shown in  FIG. 8 , the small cell coverage adjusting device may include a transceiver unit  801 , a determining unit  802 , and an adjusting unit  803 . 
     The transceiver unit  801  is configured to receive a request message carrying a coverage parameter adjusting value from a macro cell; where, the request message is sent after the macro cell determines that a load of the macro cell meets a coverage parameter value adjusting condition of a small cell, where the coverage parameter value includes an RE value of the small cell or a pilot power value of the small cell; the determining unit  802  is configured to determine whether the small cell accepts the coverage parameter adjusting value; and the adjusting unit  803  is configured to: when a determining result of determining unit  802  is yes, adjust a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     As an optional implementation manner, in the small cell coverage adjusting device shown in  FIG. 8 , transceiver unit  801  is further configured to: before receiving the request message carrying the coverage parameter adjusting value from the macro cell, send a coverage parameters report message at least carrying an identifier of the small cell and the current coverage parameter value of the small cell to the macro cell, so that when determining that the current coverage parameter value of the small cell is within an adjustable range, the macro cell selects the small cell as a small cell whose coverage parameter is to be adjusted, and sends the request message carrying the coverage parameter adjusting value. 
     As an optional implementation manner, in the small cell coverage adjusting device shown in  FIG. 8 , determining unit  802  is specifically configured to: when the coverage parameter adjusting value is higher than the current coverage parameter value of the small cell, determine whether capability information of the small cell is smaller than a preset threshold, and if yes, determine that the small cell accepts the coverage parameter adjusting value; or if no, determine that the small cell does not accept the coverage parameter adjusting value. 
     Alternatively, the determining unit  802  is specifically configured to: when the coverage parameter adjusting value is lower than the current coverage parameter value of the small cell, determine that the small cell accepts the coverage parameter adjusting value. 
     As an optional implementation manner, in the small cell coverage adjusting device shown in  FIG. 8 , if the capability information of the small cell includes HSDPA schedule timeslot duty cycle information of the small cell, the transceiver unit  701  is further configured to receive a capability information message sent by the small cell, where, the capability information message at least carries the HSDPA schedule timeslot duty cycle information of the small cell. 
     As an optional implementation manner, in the small cell coverage adjusting device shown in  FIG. 8 , the transceiver unit  801  is further configured to send a response message to the macro cell, where, the response message carries the adjusted coverage parameter value of the small cell. 
     As an optional implementation manner, in the small cell coverage adjusting device shown in  FIG. 8 , when the small cell accepts the coverage parameter adjusting values sent by multiple macro cells, the adjusting unit  803  is specifically configured to select a largest coverage parameter adjusting value from the coverage parameter adjusting values accepted by the small cell, which is sent by the multiple macro cells, according to the capability information of the small cell, and adjust the current coverage parameter value of the small cell according to the largest coverage parameter adjusting value. 
     The small cell coverage adjusting device shown in  FIG. 8  can dynamically adjust a coverage parameter of the small cell according to a current condition of the macro cell and the small cell, so that the small cell can offload services on the macro cell better; and meanwhile, the small cell blindly expanding the coverage is avoided, so as to decrease intra-frequency interference caused by the coverage of the small cell to the macro cell. 
     Referring to  FIG. 9 ,  FIG. 9  is a structural diagram of a small cell coverage adjusting system according to an embodiment of the present invention. As shown in  FIG. 9 , the small cell coverage adjusting system may include a first small cell coverage adjusting device  901  and a second small cell coverage adjusting device  902 , where, the first small cell coverage adjusting device  901  and the second small cell coverage adjusting device  902  exchange information through an Iur interface, where, the structure of the first small cell coverage adjusting device  901  is same as the structure of the small cell coverage adjusting device shown in  FIG. 6  or  FIG. 7 , and the structure of the second small cell coverage adjusting device  902  is same as the structure of the small cell coverage adjusting device shown in  FIG. 8 , which are not repeated in the embodiment of the present invention. 
     The first small cell coverage adjusting device  901  is configured to determine whether a load of a macro cell meets the coverage parameter value adjusting condition of the small cell, where, the coverage parameter value of the small cell includes an RE value of the small cell or a pilot power value of the small cell; and if the load of the macro cell meets the coverage parameter value adjusting condition of the small cell, send a request message carrying a coverage parameter adjusting value to the second small cell coverage adjusting device  902 . 
     The second small cell coverage adjusting device  902  is configured to receive the request message carrying the coverage parameter adjusting value from the first small cell coverage adjusting device  901 , and determine whether the small cell accepts the coverage parameter adjusting value, and if yes, adjust a current coverage parameter value of the small cell according to the coverage parameter adjusting value. 
     In the small cell coverage adjusting system shown in  FIG. 9 , the first small cell coverage adjusting device  901  may be an RNC of the macro cell or an RNC of the small cell or a base station of the small cell, and the second small cell coverage adjusting device  902  may be the RNC of the small cell or the base station of the small cell. 
     The small cell coverage adjusting system shown in  FIG. 9  can dynamically adjust a coverage parameter of the small cell according to a current condition of the macro cell and the small cell, so that the small cell can offload services on the macro cell better; and meanwhile, the small cell blindly expanding the coverage is avoided to decrease intra-frequency interference caused by the coverage of the small cell to the macro cell. 
     It can be clearly understood by a person skilled in the art that, for the purpose of convenient and brief description, division of the foregoing function modules is taken as an example for illustration, in actual implementation, the foregoing functions may be implemented by different function modules as required, that is, the inner structure of an apparatus is divided into different function modules to implement all or part of the functions described above. For a detailed working process of the foregoing system, apparatus, and unit, reference may be made to the corresponding process in the method embodiments, and the details will not be described herein again. 
     In the several embodiments provided in the present invention, it should be understood that, the disclosed system, apparatus, and method may be implemented in other manners. For example, the described apparatus embodiment is merely exemplary. For example, the division of the modules or units is merely logical function division and may be other division in actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces; the indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms. 
     The units described as separate parts may or may not be physically separate, and the components displayed as units may or may not be physical units, which may be located in one position, or may be distributed on a plurality of network units. A part or all of the units may be selected according to an actual need to achieve the objectives of the solutions of the embodiments. 
     In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each of the unit may physically exist as separate units, or two or more units are integrated into one unit. The integrated unit may be implemented in a form of hardware, or may be implemented in a form of a software functional unit. 
     When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of the present invention essentially, or the part contributing to the prior art, or all or a part of the technical solutions may be implemented in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for instructing a computer device (which may be a personal computer, a server, a network device, or the like) or a processor (processor) to perform all or a part of steps of the methods described in the embodiments of the present invention. The storage medium includes: any medium that can store program codes, such as a USB flash disk, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk. 
     The foregoing embodiments are merely intended for describing the technical solutions of the present invention rather than limiting the present invention. Although the present invention is described in detail with reference to the foregoing embodiments, a person of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the embodiments, or make equivalent replacements to some technical features in the technical solutions; however, as long as these modifications or replacement do not make the essence of corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.