Abstract:
A method, system and device for transmitting system information are provided, and said method includes the following steps: the network side transmits the system information on a downlink work carrier, wherein said system information includes the master system information and wireless resource configuration information of said downlink work carrier, and master system information of at least one of the other downlink carriers in multiple carriers. By using the present invention, the speed and efficiency of the terminal obtaining the system information of other downlink work carrier can be improved in multi-carrier system.

Description:
[0001]    This application claims the benefit of Chinese Patent Application no. 200910092379.2, filed with the Chinese Patent Office on Sep. 11, 2009 and entitled “Method, system and device for transmitting system information”, which is hereby incorporated by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of communications and particularly to a method, system and device for transmitting system information. 
       BACKGROUND OF THE INVENTION 
       [0003]    Numerous novel technologies have been introduced in the LTE-Advanced (LTE-A), and the technology of carrier aggregation has also been introduced therein as a key technology to support transmission with a higher bandwidth. A general principle of carrier aggregation lies in that two or more underlying carriers are aggregated together for operation to thereby satisfy a higher bandwidth demand. With the introduced technology of carrier aggregation, the number of carriers in a cell has been changed from one to more, thus giving rise to a multi-carrier communication scenario. At present, a method for transmitting and receiving system information in an LTE system has continued their usage in a method for transmitting and receiving system information in an LTE-A system. 
         [0004]    In the LTE system, there are twelve classes of LTE system information including a master system information block and a system information block  1  to a system information block  11  respectively, where the master system information block bears the bandwidth of a downlink carrier, a frame number and configuration information of a Physical Hybrid Automatic Repeat reQuest (ARQ) Indicator Channel (PHICH); the system information block  1  bears both whether the downlink carrier allows an access of a user equipment and scheduling information of the other system information blocks, where the scheduling information of the other system information blocks identifies information on the locations and periodicities at which the system information block  2  to the system information block  11  are transmitted; the system information block  2  bears a radio resource configuration condition of the downlink carrier, e.g., bandwidth information of an uplink carrier paired with the downlink carrier over which the information is borne, configuration information of a Multimedia Broadcast multicast service Single Frequency Network (MBSFN) of the downlink carrier, etc.; the system information block  3  to the system information block  8  generally bear information related to cell selection or reselection by the user equipment; if the downlink carrier belongs to a home base station, then the system information block  9  bears the identifier (ID) of the home base station, so the system information block  9  exists only when the downlink carrier belongs to a home base station; and the system information block  10  and the system information block  11  bear information related to an Earthquake and Tsunami Warning System (ETWS) of the system. 
         [0005]    In an LTE-A multi-carrier scenario, system information of a cell is configured for transmission as in the following steps: 
         [0006]    Step  101 . One downlink carrier in a cell is selected arbitrarily at the network side. 
         [0007]    Step  102 . The downlink carrier is configured with system information at the network side. 
         [0008]    (1) The master system information block is generated at the network side from the bandwidth of the downlink carrier, a frame number of the cell and PHICH configuration of the downlink carrier. 
         [0009]    (2) The system information block  1  is generated at the network side according to whether the downlink carrier allows an access of a user equipment and to the system information blocks  3  to  11  of the downlink carrier. 
         [0010]    (3) The system information block  2  is generated at the network side according to a radio resource configuration condition of the downlink carrier. 
         [0011]    (4) The system information block  3  to the system information block  11  are configured at the network side according to the cell and a condition of the entire network. 
         [0012]    Step  103 . The configured system information is transmitted from the network side over the downlink carrier. 
         [0013]    (1) The master system information block is placed at the network side over a Physical Broadcast Channel (PBCH) of the downlink carrier for transmission. 
         [0014]    (2) The system information block  1  to the system information block  11  are placed at the network side over a Physical Downlink Shared Channel (PDSCH) of the downlink carrier for transmission, and since the PDSCH is indicated over a Physical Downlink Control Channel (PDCCH), a System Information-Radio Network Temporary Identifier (SI-RNTI) of the cell is carried over the PDCCH indicating the PDSCH over which the system information is carried. 
         [0015]    Step  104 . It is determined at the network side whether there is a downlink carrier for which no system information is configured. 
         [0016]    It is determined at the network side whether there is a downlink carrier for which no system information is configured particularly in either of the following two situations: 
         [0017]    The flow goes to the step  102  when it is determined at the network side that there is a downlink carrier for which no system information is configured; or 
         [0018]    Configuration and transmission of the system information terminates when it is determined at the network side that there is no downlink carrier for which no system information is configured. 
         [0019]    In an LTE-A multi-carrier scenario, a user equipment receives system information of a cell as in the following steps: 
         [0020]    Step  201 . A user equipment detects a specific downlink carrier of a cell by capturing a downlink synchronization signal. 
         [0021]    Step  202 . The user equipment receives a master system information block of the downlink carrier over a PBCH of the downlink carrier and acquires a bandwidth and PHICH configuration information of the downlink carrier and a frame number of the cell. 
         [0022]    Step  203 . The user equipment performs blind detection of a PDCCH of the downlink carrier according to the PHICH configuration information of the downlink carrier and parses a PDSCH corresponding to a specific PDCCH, i.e., system information, upon detected inclusion of an SI-RNTI over the PDCCH, particularly in the following steps: 
         [0023]    (a) Since the system information block  1  is transmitted at a fixed location, the user equipment firstly parses the system information block  1  and acquires information on whether an access of the user equipment is allowed to the downlink carrier and scheduling information of the other system information blocks of the downlink carrier. If no access of the user equipment is allowed, then the user equipment goes to the step  201 ; otherwise, the flow goes to the step  203 (b). 
         [0024]    (b) The user equipment acquires the other system information blocks at corresponding locations according to the scheduling information of the other system information blocks in the system information block  1  and acquires corresponding system information. 
         [0025]    Step  204 . The user equipment determines whether it is necessary to acquire system information of another downlink carrier. 
         [0026]    The user equipment determines it is necessary to acquire system information of another downlink carrier particularly in either of the following two situations: 
         [0027]    The flow goes to the step  201  to repeat the processes of synchronization, listening and parsing when the user equipment determines that it is necessary to acquire system information of another downlink carrier; or 
         [0028]    The present flow ends when the user equipment determines that it is not necessary to acquire system information of any other downlink carrier. 
         [0029]    The inventors have identified during making of the invention at least the following problems in the prior art: 
         [0030]    With transmission and reception of system information of a cell in the LTE-A multi-carrier scenario in the prior art, system information of each downlink carrier in the cell is broadcasted only over that downlink carrier, and the system information is broadcasted separately between one downlink carrier and another; and when a user equipment listening to a specific downlink carrier is going to acquire system information of another downlink carrier in the cell, the user equipment has to synchronize, listen to and parse the other downlink carrier again, thus lowering the speed at which and the efficiency with which the user equipment acquires the system information of the other downlink carrier. 
       SUMMARY OF THE INVENTION 
       [0031]    Embodiments of the invention provide a method, system and user equipment for transmitting system information in order to improve the speed at which and the efficiency with which a user equipment acquires system information of a downlink carrier. 
         [0032]    An embodiment of the invention provides a method for transmitting system information, which includes:
       transmitting, from the network side, system information over a downlink carrier, which includes master system information and radio resource configuration information of the downlink carrier, and master system information of at least one other downlink carrier among a plurality of carriers.       
 
         [0034]    The system information further includes radio resource configuration information of the at least one other downlink carrier. 
         [0035]    The master system information and radio resource configuration information of each downlink carrier among the plurality of carriers is configured at the network side, and the system information is transmitted over each downlink carrier among the plurality of carriers, wherein the system information includes the master system information and the radio resource configuration information of the downlink carrier, and the master system information of the at least one other downlink carrier. 
         [0036]    The system information further includes one or more of a system information block  1  and a system information block  3  to a system information block  11  of the downlink carrier over which the system information is transmitted. 
         [0037]    The master system information of the at least one other downlink carrier is configured at the network side in a system information block  12  of the downlink carrier over which the system information is transmitted. 
         [0038]    Transmitting the system information from the network side over the downlink carrier includes:
       transmitting the master system information of the downlink carrier from the network side over a Physical Broadcast Channel, PBCH, of the downlink carrier;   transmitting the radio resource configuration information of the downlink carrier from the network side over a Physical Downlink Shared Channel, PDSCH; and   transmitting the master system information and the radio resource configuration information of the at least one other downlink carrier from the network side over the PDSCH.       
 
         [0042]    The method further includes: carrying at the network side a System Information-Radio Network Temporary Identifier, SI-RNTI, of the downlink carrier over a Physical Downlink Control Channel, PDCCH, when the radio resource configuration information of the downlink carrier is transmitted over the PDSCH of the downlink carrier; and
       carrying at the network side an SI-RNTI of the at least one other downlink carrier over the PDCCH when the radio resource configuration information of the at least one other downlink carrier is transmitted over the PDSCH of the downlink carrier.       
 
         [0044]    The method further includes: after transmitting from the network side the system information over the downlink carrier,
       a user equipment receiving the system information over the downlink carrier.       
 
         [0046]    The user equipment receiving the system information over the downlink carrier includes:
       the user equipment detecting the downlink carrier;   the user equipment receiving the master system information of the detected downlink carrier over the downlink carrier; and   the user equipment receiving other system information over the downlink carrier according to the master system information, wherein the other system information compress the radio resource configuration information of the downlink carrier, and the master system information and the radio resource configuration information of the at least one other downlink carrier.       
 
         [0050]    The user equipment receiving the other system information includes:
       the user equipment receiving the radio resource configuration information of the downlink carrier by an SI-RNTI of the downlink carrier carried over the downlink carrier; and   the user equipment receiving the radio resource configuration information of the at least one other downlink carrier by an SI-RNTI of the at least one other downlink carrier carried over the downlink carrier.       
 
         [0053]    The master system information of the downlink carrier includes:
       one or more of a frequency point, a bandwidth, a frame number and Physical HARQ Indicator Channel, PHICH, of the downlink carrier.       
 
         [0055]    An embodiment of the invention provides a communication system including:
       the network side configured to transmit system information over a downlink carrier, which includes master system information and radio resource configuration information of the downlink carrier, and master system information of at least one other downlink carrier; and   a user equipment configured to receive the system information over the downlink carrier.       
 
         [0058]    The system information further includes radio resource configuration information of the at least one other downlink carrier. 
         [0059]    The network side is further configured to configure the master system information and the radio resource configuration information of each downlink carrier among a plurality of carriers, and to transmit the system information over each downlink carrier among the plurality of carriers, wherein the system information includes the master system information and the radio resource configuration information of the downlink carrier, and the master system information of the at least one other downlink carrier. 
         [0060]    The system information further includes one or more of a system information block  1  and a system information block  3  to a system information block  11  of the downlink carrier over which the system information is transmitted. 
         [0061]    An embodiment of the invention provides a network-side device including:
       a transmitting module configured to transmit system information over a downlink carrier, which includes master system information and radio resource configuration information of the downlink carrier, and master system information of at least one other downlink carrier.       
 
         [0063]    The system information further includes radio resource configuration information of the at least one other downlink carrier. 
         [0064]    The network-side device further includes:
       a configuring module configured to configure the master system information and the radio resource configuration information of each downlink carrier among a plurality of carriers; and   the transmitting module is further configured to transmit the system information over each downlink carrier among the plurality of carriers, wherein the system information includes the master system information and the radio resource configuration information of the downlink carrier, and the master system information of the at least one other downlink carrier.       
 
         [0067]    The system information further includes one or more of a system information block  1  and a system information block  3  to a system information block  11  of the downlink carrier over which the system information is transmitted. 
         [0068]    The configuring module is further configured to configure the master system information of the at least one other downlink carrier in a system information block  12  of the downlink carrier over which the system information is transmitted. 
         [0069]    The transmitting module is further configured:
       to transmit the master system information of the downlink carrier over a Physical Broadcast Channel, PBCH, of the downlink carrier;   to transmit the radio resource configuration information of the downlink carrier over a PDSCH; and   to transmit the master system information and the radio resource configuration information of the at least one other downlink carrier over the PDSCH.       
 
         [0073]    The transmitting module is further configured to carry an SI-RNTI of the downlink carrier over a PDCCH when the radio resource configuration information of the downlink carrier is transmitted over the downlink carrier; and to carry an SI-RNTI of the at least one other downlink carriers over the PDCCH when the radio resource configuration information of the at least one other downlink carrier is transmitted. 
         [0074]    The transmitting module is further configured to instruct a user equipment to receive the system information over the downlink carrier after the system information is transmitted over the downlink carrier. 
         [0075]    The master system information of the downlink carrier includes:
       one or more of a frequency point, a bandwidth, a frame number and Physical HARQ Indicator Channel, PHICH, configuration information of the downlink carrier.       
 
         [0077]    An embodiment of the invention provides a user equipment including:
       a receiving module configured to receive system information transmitted from the network side over a downlink carrier to which the user equipment listens among a plurality of carriers, wherein the system information includes master system information and radio resource configuration information of the listened-to downlink carrier, and master system information of at least one other downlink carrier.       
 
         [0079]    The system information further includes radio resource configuration information of the at least one other downlink carrier. 
         [0080]    The system information further includes one or more of a system information block  1  and a system information block  3  to a system information block  11  of the downlink carrier over which the system information is transmitted. 
         [0081]    The receiving module includes:
       a detecting sub-module configured to detect the downlink carrier;   a first receiving sub-module configured to receive the master system information of the downlink carrier detected by the detecting sub-module over the downlink carrier; and   a second receiving sub-module configured receive other system information according to the master system information received by the first receiving sub-module over the downlink carrier, wherein the other system information includes the radio resource configuration information of the detected downlink carrier, and the master system information and the radio resource configuration information of the at least one other downlink carrier.       
 
         [0085]    The second receiving sub-module is further configured:
       to receive the radio resource configuration information of the downlink carrier over the downlink carrier by an SI-RNTI of the downlink carrier carried over the downlink carrier; and   to receive the radio resource configuration information of the at least one other downlink carrier over the downlink carrier by an SI-RNTI of the at least one other downlink carrier carried over the downlink carrier.       
 
         [0088]    The master system information of the downlink carrier includes:
       one or more of a frequency point, a bandwidth, a frame number and Physical HARQ Indicator Channel, PHICH, configuration information of the downlink carrier.       
 
         [0090]    In the embodiments of the invention, system information of at least one downlink carrier among a plurality of carriers is transmitted over the downlink carrier together with system information of at least one other downlink carrier among the plurality of carriers, so that a user equipment can receive the system information of the other downlink carrier or carriers over the corresponding downlink carrier to thereby improve the speed at which and the efficiency with which the user equipment acquires the system information of the other downlink carrier or carriers. Of course, any product according to an embodiment of the invention may not necessarily attain all the foregoing advantages at the same time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0091]    In order to describe more clearly the technical solution of the invention or in the prior art, the drawings to be used in the description of the invention or the prior art will be briefly introduced below, and apparently the drawings in the following description illustrate only some of embodiments of the invention, and other drawings can also occur to those ordinarily skilled in the art benefiting from these drawings but without any inventive effort. 
           [0092]      FIG. 1  is a flow chart of a method for configuring and transmitting system information of a plurality of carriers in the prior art; 
           [0093]      FIG. 2  is a flow chart of a method for receiving system information of a plurality of carriers in the prior art; 
           [0094]      FIG. 3  is a flow chart of a method for transmitting system information according to an embodiment of the invention; 
           [0095]      FIG. 4  is a flow chart of configuring system information of a plurality of carriers in a method for transmitting system information according to an embodiment of the invention; 
           [0096]      FIG. 5  is a flow chart of transmitting system information of a plurality of carriers in a method for transmitting system information according to an embodiment of the invention; 
           [0097]      FIG. 6  is a flow chart of receiving system information of a plurality of carriers in a method for transmitting system information according to an embodiment of the invention; 
           [0098]      FIG. 7  is a schematic structural diagram of a network-side device according to an embodiment of the invention; and 
           [0099]      FIG. 8  is a schematic structural diagram of a user equipment according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0100]    In embodiments of the invention, each downlink carrier among a plurality of carriers is configured with system information of the other downlink carriers, and the system information is transmitted over the corresponding downlink carrier, so that a user equipment can receive the system information of the other downlink carriers over the corresponding downlink carrier to thereby improve the speed at which and the efficiency with which the user equipment acquires the system information of the other downlink carriers. 
         [0101]    It shall be noted that each downlink carrier among the plurality of carriers is configured with the system information of the other downlink carriers as a preferable step for the purpose of the invention. Generally in an embodiment of the invention, it may not be necessary to configure each downlink carrier with the system information of the other downlink carriers, but it is still possible to improve the speed at which and the efficiency with which the user equipment acquires the system information of the other downlink carriers as compared with the prior art so long as at least one downlink carrier is configured with system information of the other downlink carriers. 
         [0102]    The solution of the invention will be described in the following embodiments by way of an example in which each downlink carrier among a plurality of carriers is configured and system information is transmitted over each configured downlink carrier. 
         [0103]    The technical solution of the invention will be described clearly and fully below with reference to the drawings of the invention, and apparently the described embodiments are only a part but not all of embodiments of the invention. Any other embodiments which can occur to those ordinarily skilled in the art benefiting from the embodiments of the invention but without any inventive effort shall come into the claimed scope of the invention. 
         [0104]    In order to accommodate transmission of system information of an LTE-A system, the system information of the LTE-A system is defined further to the twelve classes of system information defined for the LTE system. Firstly the defined system information of the LTE-A system will be introduced below. 
         [0105]    In order to ensure backward compatibility, all the twelve classes of system information defined for the LTE system continue their use in the system information of the LTE-A system and includes a master system information block and a system information block  1  to a system information block  11  respectively, where the master system information block bears the bandwidth of a downlink carrier, a frame number and PHICH configuration information; the system information block  1  bears both whether the downlink carrier allows an access of a user equipment and scheduling information of the other system information blocks, where the scheduling information of the other system information blocks identifies information on the locations and periodicities at which the system information block  2  to the system information block  11  are transmitted; the system information block  2  bears a radio resource configuration condition of the downlink carrier, e.g., bandwidth information of an uplink carrier paired with the downlink carrier over which the information is borne, MBSFN configuration information of the downlink carrier, etc.; the system information block  3  to the system information block  8  generally bear information related to cell selection or reselection by the user equipment; if the downlink carrier belongs to a home base station, then the system information block  9  bears the ID of the home base station, so the system information block  9  exists only when the downlink carrier belongs to a home base station; and the system information block  10  and the system information block  11  bear ETWS related information at the network side. 
         [0106]    In an embodiment of the invention, a thirteenth class of system information is added further to the original twelve classes of system information, i.e., a system information block  12  which bears at least the frequency points, bandwidths and the PHICH configuration information of all the other downlink carriers than the downlink carrier bearing the system information block. 
         [0107]    An embodiment of the invention provides a method for transmitting system information, as illustrated in  FIG. 3 , which particularly includes the following steps: 
         [0108]    Step  301 . Master system information and radio resource configuration information of each downlink carrier among a plurality of carriers is configured at the network side. 
         [0109]    System information blocks of one downlink carrier in an LTE-A system are somewhat different from those of another, but master system information and radio resource configuration information of each downlink carrier is requisite, so one or more of information of a system information block  1  and a system information block  3  to a system information block  11  of the downlink carrier can also be configured according to a radio resource status of the downlink carrier in this step in addition to the master system information and the radio resource configuration information thereof. 
         [0110]    Step  302 . For each downlink carrier among the plurality of carriers, system information of the downlink carrier is transmitted from the network side over the downlink carrier. 
         [0111]    The system information includes the master system information and the radio resource configuration information of the downlink carrier and also master system information of all the other downlink carriers and also possibly radio resource configuration information of the other downlink carriers. 
         [0112]    If one or more of the information of the system information block  1  and the system information block  3  to the system information block  11  is configured in the step  301 , then the system information in this step shall further include the one or more of the information of the system information block  1  and the system information block  3  to the system information block  11 . 
         [0113]    In the solution of this embodiment, the other downlink carriers can subsequently be identified at the side of the user equipment according to the master system information of the other downlink carriers when the master system information of the other downlink carriers is included over a carrier of the system, and preferably in this embodiment, the radio resource configuration information of the other downlink carriers is also carried in the transmitted system information to thereby improve the speed at which and the efficiency with which the user equipment identifies the other downlink carriers. 
         [0114]    The solution of this embodiment will be described in the following embodiments by way of an example in which a downlink carrier is configured with master system information and radio resource configuration information of other downlink carriers. 
         [0115]    System information of an LTE-A system is transmitted and received generally in three steps of configuring the system information, transmitting the system information and receiving the system information, and the following description will be given respectively of these steps in which the system information is transmitted in the LTE-A system. 
         [0116]    An embodiment of the invention provides a method for configuring system information of a plurality of carriers in a method for transmitting system information, as illustrated in  FIG. 4 , which particularly includes the following steps: 
         [0117]    Step  401 . A master system information block and a system information block  2  of each downlink carrier are configured at the network side. 
         [0118]    Particularly the master system information block bears the bandwidth of the downlink carrier, a frame number and PHICH configuration information; and the system information block  2  bears a radio resource configuration condition of the downlink carrier, e.g., bandwidth information of an uplink carrier paired with the downlink carrier over which the information is borne, MBSFN configuration information of the downlink carrier, etc. 
         [0119]    Specifically the master system information block and the system information block  2  of each downlink carrier are configured at the network side as follows: 
         [0120]    (1) The master system information block of each downlink carrier is configured at the network side according to the bandwidth of each downlink carrier, a frame number of a cell and PHICH configuration of the downlink carrier. 
         [0121]    (2) The system information block  2  of each downlink carrier is configured at the network side according to a radio resource configuration condition of each downlink carrier. 
         [0122]    For example, the cell is a multi-carrier cell in which there are five downlink carriers in total, and each downlink carrier is configured at the network side with one master system information block and one system information block  2 , so five master system information blocks and five system information blocks  2  in total belonging to the five different downlink carriers are configured at the network side. 
         [0123]    Step  402 . A system information block  1  of each downlink carrier is configured at the network side. 
         [0124]    The system information block  1  is generated at the network side according to scheduling information, of the system block  2  to a system information block  12  of the downlink carrier and the information blocks  2  of the other downlink carriers, over the downlink carrier, and to information on whether the present downlink carrier allows an access of a user equipment, where the scheduling information of the respective system information blocks includes information on the locations and periodicities at which the respective system information blocks are transmitted over the downlink carrier. 
         [0125]    For example, the cell is a multi-carrier cell in which there are five downlink carriers in total, and each downlink carrier is configured at the network side with one system information block  1 , so five system information blocks  1  in total belonging to the five different downlink carriers are configured at the network side so that each system information block  1  bears the information related to the corresponding downlink carrier. 
         [0126]    Step  403 . A system information block  3  to a system information block  11  of each downlink carrier are configured at the network side. 
         [0127]    Specifically the system information block  3  to the system information block  11  of each downlink carrier are configured at the network side as follows: 
         [0128]    The system information block  3  to the system information block  11  of each downlink carrier are configured at the network side according to the cell and a condition of the entire network. The system information block  3  to the system information block  8  generally bear information related to cell selection or reselection by the user equipment; if the downlink carrier belongs to a home base station, then the system information block  9  bears the ID of the home base station; otherwise, the system information block  9  is absent; and the system information blocks  10  and  11  bear ETWS related information at the network side. 
         [0129]    It shall be noted that the system information block  3  to the system information block  11  of one downlink carrier configured at the network side may the same as or different from those of another. 
         [0130]    For example, the cell is a multi-carrier cell in which there are five downlink carriers in total, and each downlink carrier is configured at the network side with the system information block  3  to the system information block  11 , so five sets of system information blocks  3  to system information blocks  11  in total belonging to the five different downlink carriers are configured at the network side. 
         [0131]    Step  404 . A system information block  12  of each downlink carrier is configured at the network side. 
         [0132]    Specifically the system information block  12  of each downlink carrier is configured at the network side according to the master system information blocks configured for the respective downlink carriers in the step  401 . The system information block  12  bears at least master system information, including the frequency points and bandwidths and the PHICH configuration information, of all the other downlink carriers in the cell than the downlink carrier bearing the system information block  12 . 
         [0133]    For example, the cell is a multi-carrier cell in which there are five downlink carriers in total, and the system information  12  of the downlink carrier  1  includes master system information of the other four downlink carriers than the downlink carrier  1 . The other downlink carriers are configured similarly to the downlink carrier  1 , and a repeated description will be omitted here. 
         [0134]    It shall be noted that the step  401 , the step  402 , the step  403  and the step  404  can be performed in a variable order so long as the step  404  is performed after the step  401 . 
         [0135]    In the step  401  to the step  404 , the system information of each downlink carrier is configured at the network side so that the system information of each downlink carrier in the plurality of carriers includes the master system information blocks of the present downlink carrier and all the other downlink carriers. 
         [0136]    An embodiment of the invention provides a method for transmitting system information of a plurality of carriers in a method for transmitting system information, as illustrated in  FIG. 5 , which particularly includes the following steps: 
         [0137]    Step  501 . One downlink carrier is selected arbitrarily at the network side. 
         [0138]    Step  502 . A transmission mode of system information of the downlink carrier is configured at the network side. 
         [0139]    The transmission mode of the system information of the downlink carrier is configured at the network side as follows: a transmission mode of a master system information block of the downlink carrier, a transmission mode of a system information block  2  of the downlink carrier and system information blocks  2  of other downlink carriers, a transmission mode of a system information block  1 , and a transmission mode of a system information block  3  to a system information block  12  of the downlink carrier are configured at the network side particularly in the following steps: 
         [0140]    (1) The transmission mode of the master system information block of the downlink carrier is configured at the network side. 
         [0141]    Specifically the master system information block of the downlink carrier is placed at the network side over a PBCH of the downlink carrier for transmission. 
         [0142]    (2) The transmission mode of the system information block  2  of the downlink carrier and the system information blocks  2  of the other downlink carriers are configured at the network side. 
         [0143]    The system information block  2  of the downlink carrier and the system information blocks  2  of the other downlink carriers are placed at the network side over a PDSCH of the downlink carrier for transmission. 
         [0144]    At this time there are system information blocks  2  of a plurality of downlink carriers over the PDSCH and information borne over the PDSCH is indicated over a PDCCH, so SI-RNTIs corresponding to the different downlink carriers are carried over the PDCCH indicating the PDSCH to indicate the different system information blocks  2 . 
         [0145]    Specifically the system information block  2  is carried as under such a specific rule: an SI-RNTI with the value of FFFF (hexadecimal) is added over the PDCCH indicating the PDSCH over which the system information block  2  of the downlink carrier is borne; and SI-RNTIs with a number M of values selected from FFF 3  to FFFC are added over the PDCCH indicating the PDSCH over which the system information blocks  2  of the other downlink carriers are borne, wherein M+1 represents the number of downlink carriers in the cell, and a one-to-one correspondence relationship exists between these SI-RNTIs and other downlink carriers and is known to both the network side and the user equipment. For example, it is agreed in advance between the system and the user equipment that FFF 3  to FFF 6  indicate the system information of all the other downlink carriers than the listened-to downlink carrier and that these SI-RNTIs correspond one-to-one to the values of frequency points of the downlink carriers in accordance with the order of the size of values, that is, FFF 3  corresponds to the downlink carrier at the lowest frequency among all the other downlink carriers than the listened-to downlink carrier, and FFF 6  corresponds to the downlink carrier at the highest frequency among all the other downlink carriers than the listened-to downlink carrier. 
         [0146]    It shall be noted that at least the system information block  2  of the downlink carrier is carried over the downlink carrier and the other downlink carriers with their system information blocks  2  being carried are determined at the network side dependent upon load conditions of the respective downlink carriers and other factors. 
         [0147]    (3) The transmission mode of the system information block  1  of the downlink carrier is configured at the network side. 
         [0148]    The system information block  1  is placed at the network side over the PDSCH of the downlink carrier for transmission, and the SI-RNTI (FFFF) of the downlink carrier is carried over the PDCCH indicating the PDSCH over which the system information is borne. 
         [0149]    (4) The transmission mode of the system information block  3  to the system information block  12  of the downlink carrier is configured at the network side. 
         [0150]    The system information block  3  to the system information block  12  are placed at the network side over the PDSCH of the downlink carrier for transmission, and the SI-RNTI (FFFF) of the downlink carrier is carried over the PDCCH indicating the PDSCH over which the system information is borne. 
         [0151]    It shall be noted that the system information block  3  to the system information block  11  are required to be carried and whether to carry the system information block  12  is optional and determined at the network side. 
         [0152]    Step  503 . It is determined at the network side whether there is a downlink carrier for which no transmission mode of system information of the downlink carrier is configured. 
         [0153]    Specifically it is determined at the network side whether there is a downlink carrier for which no transmission mode of system information of the downlink carrier is configured in either of the following two situations: 
         [0154]    (a) The flow goes to the step  502  when it is determined at the network side that there is a downlink carrier for which no transmission mode of system information of the downlink carrier is configured; or 
         [0155]    (b) The flow goes to the step  504  when it is determined at the network side that there is not any downlink carrier for which no transmission mode of system information of the downlink carrier is configured. 
         [0156]    Step  504 . The system information is transmitted from the network side over each downlink carrier in the configured transmission mode of the system information of each downlink carrier. 
         [0157]    It shall be noted that the transmission modes of the various system information can be configured in the step  502  in a variable order. 
         [0158]    In the steps  501  to  503 , for each downlink carrier among the plurality of carriers, the master system information blocks of the present downlink carrier and all the other downlink carriers are transmitted from the network side, and possibly also the system information blocks  2  of the other downlink carriers can be carried, over the present downlink carrier. 
         [0159]    An embodiment of the invention provides a method for receiving system information of a plurality of carriers in a method for transmitting system information, as illustrated in  FIG. 6 , which particularly includes the following steps: 
         [0160]    In an LTE-A multi-carrier scenario, a user equipment receives system information of a cell as in the following steps: 
         [0161]    Step  601 . A user equipment detects a specific downlink carrier of a cell by capturing a downlink synchronization signal. 
         [0162]    Step  602 . The user equipment receives a master system information block over the downlink carrier over a PBCH of the downlink carrier and acquires a bandwidth and PHICH configuration information of the downlink carrier and a frame number of the cell. 
         [0163]    Step  603 . The user equipment parses system information over the downlink carrier. 
         [0164]    Specifically the user equipment performs blind detection of a PDCCH of the downlink carrier after acquiring the PHICH configuration information of the downlink carrier. Blind detection refers to that the user equipment which has no knowledge of a transmission location or a modulating and encoding scheme of a PDCCH at the network side attempts various possibilities of respective occurrence locations and modulation and encoding schemes of the PDCCH to detect the PDCCH. A PDSCH corresponding to a specific PDCCH, i.e., system information, is parsed upon detected inclusion of an SI-RNTI over the PDCCH, particularly in the following steps: 
         [0165]    (a) Since the system information block  1  is transmitted at a fixed location, the user equipment firstly parses the system information block  1 . The system information block  1  includes scheduling information of respective system information blocks over the downlink carrier and information on whether the present downlink carrier allows an access, where the scheduling information of the respective system information blocks over the downlink carrier includes information on the locations and periodicities at which the respective system information blocks are transmitted over the downlink carrier. Therefore it is firstly determined whether an access of the user equipment to the downlink carrier is allowed according to the system information block  1 . 
         [0166]    The flow goes to the step  601  when no access of the user equipment is allowed; or 
         [0167]    The flow goes to the step  603 ( 2 ) when an access of the user equipment is allowed. 
         [0168]    (2) Secondly the user equipment acquires the other system information blocks at corresponding locations according to the scheduling information of the other system information blocks in the system information block  1  and acquires corresponding system information borne in the other system information blocks. 
         [0169]    Specifically the corresponding system information borne in the other system information blocks includes: 
         [0170]    (a) The master system information block of the downlink carrier; and 
         [0171]    (b) The system information  2  of the downlink carrier and the carried system information blocks  2  of the other downlink carriers. 
         [0172]    It shall be noted that the user equipment acquires the system information blocks  2  of the other downlink carriers which may not necessarily be the system information blocks  2  of all the other downlink carriers but may only the system information blocks  2  carried at the network side over the downlink carrier. 
         [0173]    Since there are a plurality of system information blocks  2  corresponding to different downlink carriers, the user equipment distinguishes the system information blocks  2  of the downlink carriers corresponding to different SI-RNTIs by the SI-RNTIs. A distinguishing method complies with a relationship known to both the user equipment and the network side and particularly is similar to the identifying method in the step  502 , and a repeated description will be omitted here. 
         [0174]    (c) The system information block  3  to the system information block  11  and the system information block  12  of the downlink carrier. 
         [0175]    It shall be noted that the user equipment can acquire the system information block  12  of the downlink carrier only if the system information block  12  is carried at the network side over the downlink carrier. 
         [0176]    That is, the user equipment can acquire the master system information block, the system information block  2  and the system information block  3  to the system information block  11  over the downlink carrier; and the user equipment can acquire the system information blocks  2  and  12  related to the other downlink carriers only if they are carried at the network side over the downlink carrier. 
         [0177]    In the steps  601  to  603 , the user equipment acquires over one downlink carrier in the cell among the plurality of carriers the master system information blocks of the present downlink carrier and all the other downlink carriers, and the system information blocks  2  of the other downlink carriers carried over the present downlink carrier. 
         [0178]    An embodiment of the invention provides a communication system including:
       the network side configured to transmit system information over a downlink carrier, which includes master system information and radio resource configuration information of the downlink carrier, and master system information of at least one other downlink carrier; and   a user equipment configured to receive the system information over the downlink carrier.       
 
         [0181]    The network side is further configured to configure the master system information and the radio resource configuration information of each downlink carrier among a plurality of carriers, and for each downlink carrier among the plurality of carriers, to transmit the system information over the downlink carrier, which includes the master system information and the radio resource configuration information of the downlink carrier, and the master system information of the other downlink carriers. 
         [0182]    An embodiment of the invention provides a network-side device  70 , as illustrated in  FIG. 7 , which includes:
       a transmitting module  72  configured to transmit system information over a downlink carrier, which includes master system information and radio resource configuration information of the downlink carrier, and master system information of at least one other downlink carrier.       
 
         [0184]    The system information further includes radio resource configuration information of the at least one other downlink carrier. 
         [0185]    The network-side device  70  further includes a configuring module  71  configured to configure the master system information and the radio resource configuration information of each downlink carrier among a plurality of carriers; and the transmitting module  72  is further configured to transmit the system information over each downlink carrier among the plurality of carriers, where the system information includes the master system information and the radio resource configuration information of the downlink carrier, and the master system information of the at least one other downlink carrier. 
         [0186]    The configuring module  71  is further configured, for each downlink carrier among the plurality of carriers, to configure the master system information of all the other downlink carriers in a system information block  12  of the downlink carrier. 
         [0187]    The transmitting module  72  is further configured:
       to transmit the master system information of the downlink carrier over a Physical       
 
         [0189]    Broadcast Channel (PBCH) of the downlink carrier;
       to transmit the radio resource configuration information of the downlink carrier over a PDSCH of the downlink carrier; and   to transmit the master system information of all the other downlink carriers and/or the radio resource configuration information of the one or more other downlink carriers over the PDSCH of the downlink carrier.       
 
         [0192]    And
       the transmitting module  72  is further configured to carry an SI-RNTI of the downlink carrier over a PDCCH when the transmitting module transmits the radio resource configuration information of the downlink carrier over the PDSCH of the downlink carrier; and   the transmitting module  72  is further configured to carry an SI-RNTI or SI-RNTIs of the one or more other downlink carriers over the PDCCH when the transmitting module transmits the radio resource configuration information of the one or more other downlink carriers over the PDSCH of the downlink carrier.       
 
         [0195]    And after the transmitting module  72  transmits the system information of the downlink carrier over the downlink carrier,
       the user equipment receives the system information of the downlink carrier transmitted from the transmitting module  72  over the downlink carrier.       
 
         [0197]    The master system information of the downlink carrier includes:
       one or more of a frequency point, a bandwidth, a frame number and Physical HARQ       
 
         [0199]    Indicator Channel (PHICH) configuration information of the downlink carrier. 
         [0200]    An embodiment of the invention provides a user equipment  80 , as illustrated in  FIG. 8 , which includes:
       a receiving module  81  configured to receive system information transmitted from the network side over a downlink carrier to which the user equipment listens among a plurality of carriers, where the system information includes master system information and radio resource configuration information of the listened-to downlink carrier, and master system information of at least one other downlink carrier.       
 
         [0202]    The system information further includes radio resource configuration information of the at least one other downlink carrier. 
         [0203]    The system information further includes one or more of a system information block  1  and a system information block  3  to a system information block  11  of the downlink carrier over which the system information is transmitted. 
         [0204]    The receiving module  81  includes:
       a detecting sub-module  811  configured to detect the downlink carrier;   a first receiving sub-module  812  configured to receive the master system information of the downlink carrier detected by the detecting sub-module  811  over the downlink carrier; and   a second receiving sub-module  813  configured to receive other system information according to the master system information received by the first receiving sub-module over the downlink carrier, where the other system information includes the radio resource configuration information of the detected downlink carrier, and the master system information and the radio resource configuration information of the at least one other downlink carrier.       
 
         [0208]    When the second receiving sub-module  813  receives the other system information among the system information of the downlink carrier than the master system information of the downlink carrier according to the master system information received by the first receiving sub-module  812  over the downlink carrier, the second receiving sub-module  813  is further configured:
       to receive the radio resource configuration information of the downlink carrier over the downlink carrier by an SI-RNTI of the downlink carrier carried over the downlink carrier; and   to receive the radio resource configuration information of the at least one other downlink carrier over the downlink carrier by an SI-RNTI of the at least one other downlink carrier carried over the downlink carrier.       
 
         [0211]    The master system information of the downlink carrier includes:
       one or more of a frequency point, a bandwidth, a frame number and Physical HARQ Indicator Channel (PHICH) configuration information of the downlink carrier.       
 
         [0213]    In the embodiments of the invention, each downlink carrier among a plurality of carriers is configured with system information of the other downlink carriers, and the system information is transmitted over the corresponding downlink carrier, so that a user equipment can receive the system information of the other downlink carriers over the corresponding downlink carrier to thereby improve the speed at which and the efficiency with which the user equipment acquires the system information of the other downlink carriers. Of course, any product according to an embodiment of the invention may not necessarily attain all the foregoing advantages at the same time. 
         [0214]    The solution of the invention has been described in the foregoing respective embodiments in which the operations are performed at the network side for each downlink carrier among a plurality of carriers, but the embodiments of the invention will not be limited to the solution in which the operations are performed at the network side over at least one downlink carrier to address the technical problem of the invention. 
         [0215]    The operations at the network side over a downlink carrier includes configuring master system information and radio resource configuration information of the downlink carrier and transmitting system information over the downlink carrier, which includes the master system information and the radio resource configuration information of the downlink carrier and master system information of at least one other downlink carrier, and possibly further includes radio resource configuration information of the at least one other downlink carrier. 
         [0216]    With the foregoing description of the embodiments, those skilled in the art can appreciate clearly that the invention can be embodied in software plus a necessary general-purpose hardware platform and of course can alternatively be embodied in hardware, but the former is a preferable implementation in many cases. Based upon such understanding, the technical solution of the invention in essence or the part thereof contributing to the prior art can be embodied in the form of a computer software product which is stored in a storage medium and which includes several instructions to enable an end device (e.g., a mobile phone, a personal computer, a server, a network device, etc.) to perform the methods according to the respective embodiments of the invention. 
         [0217]    The foregoing description is merely illustrative of the preferred embodiments of the invention, and it shall be noted that those ordinarily skilled in the art can further make several modifications and variations without departing from the sprit of the invention and these modifications and variations shall also come into the claimed scope of the invention.