Abstract:
A radio terminal, radio base station, channel signal forming method and channel signal receiving method wherein when an upstream unit band and a plurality of downstream unit bands associated therewith are used to perform communications, the quality of downstream assignment control information can be prevented from being degraded. In a base station ( 100 ), the PDCCH signals including upstream assignment control information are limited to ones that are placed in some of the downstream unit bands. This can reduce the probability of performance of zero padding to downstream assignment control information having greater importance. Also in the base station ( 100 ), the PDCCH signals of the downstream unit bands other than the basic unit band include only downstream resource assignment information. For this reason, in the individual regions of the downstream unit bands other than the basic unit band, the bandwidth of the downstream unit bands is always used as a reference of size adjustment and hence requires no information size adjustment. As a result, there is no need of performing zero padding to the downstream assignment control information, so that the quality of downstream assignment control information can be prevented from being degraded.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a radio terminal, radio base station, channel signal forming method and channel signal receiving method. 
       BACKGROUND ART 
       [0002]    In 3GPP LTE, OFDMA (Orthogonal Frequency Division Multiple Access) is employed as a downlink communication method. In a radio communication system adopting 3GPP LTE, a base station transmits a synchronizing signal (synchronization channel: SCH) and a broadcast signal (broadcast channel: BCH) using prescribed communication resources. A terminal first synchronizes with a base station by capturing the SCH. Then, the terminal acquires parameters that are specific to that base station (for example, the frequency bandwidth) by reading BCH information (see Non-patent Literature 1, 2 and 3). 
         [0003]    Also, after the terminal acquires base station-specific parameters, the terminal sends a connection request to the base station, and, by this means, establishes communication with the base station. When necessary, the base station transmits control information to the terminal, with which communication has been established, using a PDCCH (Physical Downlink Control CHannel). 
         [0004]    The terminal performs “blind detection” for the received PDCCH signal. That is, a PDCCH signal includes a CRC (Cyclic Redundancy Check) part, and, at a base station, this CRC part is masked by the terminal ID of the target terminal. Thus, until a terminal demasks the CRC part of a received PDCCH signal with the terminal&#39;s terminal ID, the terminal cannot decide whether or not the PDCCH signal is for that terminal. In this blind detection, if the result of demasking is that CRC calculation is OK, the PDCCH signal is decided to be sent for the terminal. 
         [0005]    Also, control information sent by a base station includes assignment control information including, for example, information about resources which a base station allocates to a terminal. A terminal needs to receive both downlink assignment control information and uplink assignment control information which have a plurality of formats. Although downlink assignment control information which a terminal should receive can be defined in a plurality of sizes depending on the transmitting antenna control method and frequency allocation method at a base station, some of these downlink assignment control information formats (hereinafter simply referred to as “downlink assignment control information”) and uplink assignment control information formats (hereinafter simply referred to as “uplink assignment control information”) are transmitted using PDCCH signals of the same size. A PDCCH signal includes type information of assignment control information (for example, a 1 bit flag). Thus, even if the size of a PDCCH signal including downlink assignment control information and the size of a PDCCH signal including uplink assignment control information are the same, a terminal checks type information of assignment control information, and by this means can distinguish between downlink assignment control information and uplink assignment control information. The PDCCH format to transmit uplink assignment control information is PDCCH format 0, and the PDCCH format to transmit downlink assignment control information, transmitted in a PDCCH signal of the same size as for uplink assignment control information, is PDCCH format 1A. 
         [0006]    However, cases might occur where the information size of uplink assignment control information determined from the uplink bandwidth (that is, the number of bits required for transmission) and the information size of downlink assignment control information determined from the downlink bandwidth differ. To be more specific, if an uplink bandwidth is small, the information size of uplink assignment control information becomes small, and, if a downlink bandwidth is small, the information size of downlink assignment control information becomes small. If a difference in bandwidth results in a difference in the information size like this, by adding zero information to the smaller assignment control information (that is, by performing zero-padding), the size of downlink assignment control information and the size of uplink assignment control information are made equal. By this means, whether the content is downlink assignment control information or uplink assignment control information, PDCCH signals have the same size. 
         [0007]    The size adjustment of control information as mentioned above reduces the number of times of blind detection at a terminal on the receiving side. However, when a downlink transmission bandwidth of a base station is wide, a base station transmits many PDCCH signals at once, so that a terminal cannot reduce the number of times of blind detection much in its normal operation, and the increase of circuit scale causes a problem. 
         [0008]    Therefore, to reduce the number of times of blind detection on a terminal more, a terminal employs the method to limit a physical region where a terminal receives control information. Thus, each terminal is reported in advance the time and frequency region that may include control information for that terminal, and performs blind detection only in a terminal-specific region where control information for that terminal is likely to be included. This terminal-specific physical region is called “dedicated region (UE SS: UE specific Search Space).” This dedicated region is associated with for example, terminal ID. Also, a time and frequency interleaving is employed to keep the effect of time diversity and frequency diversity at a certain level in the whole dedicated region. 
         [0009]    On the other hand, a PDCCH signal includes control information that is reported at once to a plurality of terminals (for example, scheduling information about downlink broadcast signal). To transmit this control information, a physical region that is common to all terminals, called “common region (Common SS: Common Search Space),” is prepared in a PDCCH signal. 
         [0010]    A terminal requires both control information included in a dedicated region and control information included in a common region, so that a terminal needs to perform blind detection for all of uplink control information and downlink control information included in a dedicated region and uplink control information and downlink control information included in a common region. 
         [0011]    Also, the standardization of 3GPP LTE-advanced has been started to realize much faster communication than 3GPP LTE. 3GPP LTE-advanced system (hereinafter referred to as “LTE-A system”) adheres 3GPP LTE system (hereinafter referred to as “LTE system”). In 3GPP LTE-advanced, to realize a downlink transmission speed up to maximum 1 Gbps, a base station and a terminal which can communicate in wideband frequency of 20 MHz or more are expected to be introduced. 
         [0012]    Also, in 3GPP LTE-Advanced, throughput requirements for an uplink and a downlink are different, so that communication bandwidths for an uplink and a downlink may be made asymmetric. Specifically, in 3GPP LTE-Advanced, it is considered to make the communication bandwidth of a downlink wider than the communication bandwidth of an uplink. 
         [0013]    Here, a base station to support LTE-A system (hereinafter referred to as “LTE-A base station”) is formed to be able to communicate using a plurality of “component bands.” “Component band” is a bandwidth for maximum 20 MHz here and is defined as the basic unit of communication band. Furthermore, “component band” in a downlink (hereinafter referred to as “downlink component band”) is defined as a band separated by downlink frequency bandwidth information in BCH broadcasted from a base station, or a band defined by the range of distribution when a downlink control channel (PDCCH) is arranged in a distributed manner. Also, “component band” in an uplink (hereinafter referred to as “uplink component band”) is defined as a band separated by uplink frequency bandwidth information in BCH broadcasted from a base station, or the basic unit of a communication band of 20 MHz or less including a PUSCH (Physical Uplink Shared CHannel) near the center, and a PUCCH for an LTE on both ends. Also, in 3GPP LTE-Advanced, “component band” may be designated as “Component Carrier (s)” in English. 
         [0014]      FIG. 1  is a diagram showing an arrangement example of each channel in an LTE-A system where the communication bandwidth and the numbers of component bands of an uplink and a downlink are asymmetric. In  FIG. 1 , to let a terminal transmit an uplink signal, an LTE-A base station reports assignment control information using PDCCH from both two downlink component bands. Since an uplink component band is associated with both downlink component bands, regardless of the PDCCH whichever downlink component band is used, the PUSCH is transmitted in the same uplink band. Also, downlink assignment control information may be transmitted from both two downlink component bands, and is used to indicate downlink assignment control information in a downlink component band where each piece of downlink resource assignment information was transmitted, to a terminal. 
         [0015]    By receiving assignment control information in this way, an LTE-A terminal can receive a plurality of component bands at the same time. However, an LTE terminal can receive only one component band at once. To group a plurality of component bands as an allocation band for single communication is called “carrier aggregation (Carrier aggregation).” This carrier aggregation can improve throughput. 
       CITATION LIST 
     Non Patent Literature 
       [0000]    
       
         NPL 1 
         3GPP TS 36.211 V8.4.0, “Physical Channels and Modulation (Release 8),” September 2008 
         NPL 2 
         3GPP TS 36.212 V8.4.0, “Multiplexing and channel coding (Release 8),” September 2008 
         NPL 3 
         3GPP TS 36.213 V8.4.0, “Physical layer procedures (Release 8),” September 2008 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0022]    Meanwhile, in  FIG. 1 , the communication bandwidth of an LTE-A system is 30 MHz in the downlink, and includes 20 MHz downlink component band in a low frequency side and 10 MHz downlink component band in a high frequency side. On the other hand, an uplink is 20 MHz and includes one uplink component band. 
         [0023]    In  FIG. 1 , the bandwidths of a downlink component band and an uplink component band in low frequency side are equal, so that, as for this pair, the information size of uplink assignment control information and downlink assignment control information is nearly the same. Thus, zero-padding is rarely performed. By contrast with this, since the bandwidths of a downlink component band and an uplink component band in high frequency side become larger, as for this pair, much zero information is added to the smaller downlink assignment control information until this downlink assignment control information size becomes equal to the uplink assignment control information size. However, zero-padding is performed for size adjustment, and zero information itself carries no meaning. Thus, downlink assignment control information includes fundamentally unnecessary signal, so that if overall power is fixed, power per information bit fundamentally necessary declines. 
         [0024]    Also, generally, downlink assignment control information is more significant than uplink assignment control information That is, downlink assignment control information is used to report not only resource assignment information of a downlink data channel, but also scheduling information of other important information, such as paging information and broadcast information. Thus, it is preferable a frequency of zero-padding to downlink assignment control information to decrease. 
         [0025]    Here, frequency diversity effect that a PDCCH can achieve depends on the bandwidth of a downlink component band. Thus, since in the downlink component band of a narrow bandwidth frequency diversity effect becomes smaller, a cause that will reduce quality should be removed as much as possible. However, as for zero-padding, the narrower the bandwidth of a downlink component band is, the higher the possibility zero-padding is performed. 
         [0026]    This kind of situation cannot occur in an LTE system where no carrier aggregation concept exists since generally a downlink frequency bandwidth is larger than an uplink frequency bandwidth associated with the downlink frequency bandwidth. On the other hand, in an LTE-A system, where carrier aggregation is introduced and where furthermore a plurality of downlink component bands are associated with one uplink component band, although a downlink frequency bandwidth is larger than an uplink frequency bandwidth on the whole, as for the component band, the situation where a downlink component band is narrower than an uplink component band may occur frequently. 
         [0027]    Also, to avoid zero-padding, a method of making the information sizes of uplink assignment control information and downlink assignment control information different is also possible. However, in this case, a terminal has to perform blind detection separately for two pieces of assignment control information having different numbers of information bits. Thus, the number of times of blind detection increases, and, accompanying this, the increase of circuit scale becomes a problem. 
         [0028]    In view of the above, it is an object of the present invention to provide a radio terminal, radio base station, channel signal for forming method and channel signal receiving method, when communicating with an uplink component band and a plurality of downlink component bands associated with the uplink component band, by reducing the frequency to perform size adjustment processing for downlink assignment control information to prevent the quality of downlink assignment control information from being degrading. 
       Solution of Problem 
       [0029]    A radio base station according to the present invention is a radio base station that allocates component band groups on a per radio terminal basis and that is able to communicate with radio terminals using a component band groups, each component band group being formed with an uplink component band and a plurality of downlink component bands associated with the uplink component band, and that employs a configuration having; a forming section that forms channel signals on a per downlink component band basis, each channel signal having a common region that is common between all radio terminals and a dedicated region that is allocated to an individual radio terminal on a dedicated basis, downlink assignment control information for an arbitrary target terminal being included in the common region and in the dedicated region, in all channel signals to be transmitted in a downlink component band allocated to the arbitrary target terminal, uplink assignment control information for the arbitrary target terminal being included in the dedicated region only in part of the channel signals, and included in the common region at least in the part of the channel signals; and, an information size adjustment section that adjusts an information size of uplink control information and downlink control information for the arbitrary target terminal, included in the formed channel signals, based on a size adjustment reference, in all downlink component bands that are allocated to the arbitrary target terminal, in the common region, a larger one of a downlink assignment control information size determined from a bandwidth of a downlink component band in which a channel signal having the common region is sent, and an uplink assignment control information size determined from a bandwidth of an uplink component band associated with the downlink component band, being used as a size adjustment reference, in a dedicate region including uplink assignment control information for the arbitrary target terminal, the larger one of the downlink assignment control information size determined from the bandwidth of the downlink component band in which the channel signal having the dedicated region is sent, and the uplink assignment control information size determined from the bandwidth of the uplink component band associated with the downlink component band, being used as the size adjustment reference, in a dedicate region not including uplink assignment control information for the arbitrary target terminal, the downlink assignment control information size determined from the bandwidth of the downlink component band in which the channel signal having the dedicated region is sent, being used as the size adjustment reference. 
         [0030]    A radio terminal according to the present invention is a radio terminal that is able to communicate with a radio base station using a component band group that is allocated by the radio base station and that is formed with an uplink component band and a plurality of downlink component bands associated with the uplink component band, and that includes a radio receiving section that receives channel signals on a per downlink component band basis, each channel signal having a common region that is common between all radio terminals and a dedicated region that is allocated to an individual radio terminal on a dedicated basis, and including uplink assignment control information and downlink assignment control information; a determining section that determines a basic information size to use in a receiving process of channel signals of each downlink component band; and a channel signal receiving process section that performs the receiving process of the channel signals based on the basic information size, where in all downlink component bands that are allocated to the radio terminal, in the common region, the determining section determines the basic information size based on the larger one of a downlink assignment control information size determined from a bandwidth of a downlink component band in which a channel signal having the common region is sent, and an uplink assignment control information size determined from a bandwidth of an uplink component band associated with the downlink component band; in a dedicate region including uplink assignment control information for the radio terminal, the determining section determines the basic information size based on the larger one of the downlink assignment control information size determined from the bandwidth of the downlink component band in which a channel signal having the dedicated region is sent, and the uplink assignment control information size determined from the bandwidth of the uplink component band associated with the downlink component band; and in a dedicate region not including uplink assignment control information for the radio terminal, the determining section determines the basic information size based on the downlink assignment control information size determined from the bandwidth of the downlink component band in which the channel signal having the dedicated region is sent. 
         [0031]    A channel signal forming method according to the present invention is a channel signal forming method that forms channel signals for a plurality of downlink component bands associated with an uplink component band, and that includes the steps of: forming channel signals on a per downlink component band basis, each channel signal having a common region that is common between all radio terminals and a dedicated region that is allocated to an individual radio terminal on a dedicated basis; and adjusting the information size of uplink assignment control information and downlink assignment control information included in the formed channel signals, based on a size adjustment reference, where downlink assignment control information the arbitrary target terminal being included in the common region and the dedicated region in all channel signal to be transmitted in the downlink component band allocated to the arbitrary target terminal, uplink assignment control information for the arbitrary target terminal being included in the dedicated region only in part of the channel signals, and included in the common region at least in the part of the channel signals; and in all downlink component bands that are allocated to the arbitrary target terminal, in the common region, the larger one of the information size of downlink assignment control information determined from the bandwidth of the downlink component band in which the channel signal having the common region is sent, and the information size of uplink assignment control information determined from the bandwidth of the uplink component band associated with the downlink component band, being used as the size adjustment reference, in the dedicate region including the uplink assignment control information for the arbitrary target terminal, the larger one of the information size of downlink assignment control information determined from the bandwidth of the downlink component band in which the channel signal having the dedicated region is sent, and the information size of uplink assignment control information determined from the bandwidth of the uplink component band associated with the downlink component band, being used as the size adjustment reference, in the dedicate region not including the uplink assignment control information to the arbitrary target terminal, the information size of downlink assignment control information determined from the bandwidth of the downlink component band in which the channel signal having the dedicated region is sent, being used as the size adjustment reference. 
         [0032]    A channel signal receiving method according to the present invention is a channel signal receiving method that receives channel signals for a plurality of downlink component bands associated with an uplink component band, and that includes the steps of: receiving channel signals having a common region that is common between all radio terminals and a dedicated region that is allocated to an individual radio terminals on a dedicated basis, and including uplink assignment control information and downlink assignment control information; determining the basic information size to use in a receiving process of the channel signals of each downlink component band; and performing a receiving process of the channel signals based on the basic information size, where in all downlink component bands that are allocated to the radio terminal, in the common region, the basic information size is determined based on the larger one of an information size of a downlink assignment control information determined from a bandwidth of a downlink component band in which the channel signal having the common region is sent, and an information size of uplink assignment control information determined from a bandwidth of an uplink component band associated with the downlink component band, in the dedicate region including the uplink assignment control information for the radio terminal, the basic information size is determined based on the larger one of the information size of downlink assignment control information determined from the bandwidth of the downlink component band in which the channel signal having the dedicated region is sent, and the information size of uplink assignment control information determined from the bandwidth of the uplink component band associated with the downlink component band; and in the dedicate region not including uplink assignment control information for the radio terminal, the basic information size is determined based on the information size of downlink assignment control information determined from the bandwidth of the downlink component band in which the channel signal having the dedicated region is sent. 
       Advantageous Effects of Invention 
       [0033]    The present invention provides radio terminal, radio base station, channel signal forming method, and channel signal receiving method to prevent the quality of downlink assignment control information from degrading. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  shows an arrangement example of each channel in an LTE-A system where the communication bandwidth (the number of component bands) is asymmetric between an uplink and a downlink; 
           [0035]      FIG. 2  is a block diagram showing a configuration of a base station according to Embodiment 1 of the present invention; 
           [0036]      FIG. 3  is a block diagram showing a configuration of a terminal according to Embodiment 1 of the present invention; 
           [0037]      FIG. 4  shows operations of a base station and a terminal; 
           [0038]      FIG. 5  shows the method of determining size adjustment reference of downlink assignment control information; 
           [0039]      FIG. 6  shows the method of determining size adjustment reference of downlink assignment control information; 
           [0040]      FIG. 7  shows the method of determining size adjustment reference of downlink assignment control information; 
           [0041]      FIG. 8  shows the method of determining size adjustment reference of downlink assignment control information; 
           [0042]      FIG. 9  is a block diagram showing a configuration of a base station according to Embodiment 2 of the present invention; 
           [0043]      FIG. 10  is a block diagram showing a configuration of a terminal according to Embodiment 2 of the present invention; and 
           [0044]      FIG. 11  shows operations of a base station and a terminal. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0045]    Now, embodiments of the present invention will be explained in detail with reference to the accompanying drawings. Here, in embodiments, the same components will be assigned the same reference numerals and their explanations will be omitted. 
       Embodiment 1 
       [0046]      FIG. 2  is a block diagram showing a configuration of base station  100  according to Embodiment 1 of the present invention. In  FIG. 2 , base station  100  includes control section  101 , PDCCH generating section  102 , information size adjusting section  103 , CRC (Cyclic Redundancy Check) adding section  104 , modulating section  105  and  106 , SCH/BCH generating section  107 , multiplexing section  108 , IFFT section  109 , CP adding section  110 , RF transmission section  111 , RF reception section  112 , CP removing section  113 , FFT section  114 , extracting section  115 , IDFT section  116 , and data reception section  117 . Base station  100  is configured to be able to communicate with terminal  200  (described later) using a component band group composed of an uplink component band and a plurality of downlink component bands associated with the uplink component band. A component band group is set for each terminal  200 . Some or all of a plurality of component bands composing the component band group allocated to first terminal  200  may overlap with a constituent component band of the component band group allocated to second terminal  200 . 
         [0047]    Control section  101  generates control information (including uplink assignment control information and downlink assignment control information) and region assignment information indicating to which one of a dedicated region or a common region each piece of control information is allocated. This control information includes component band group setting information individually set for each terminal  200 , “basic component band information (Anchor Carrier)” (described later), dedicated assignment control information, such as resource assignment information in component bands composing a component band group, and common assignment control information which is common to all terminals  200 . While dedicated region assignment control information is generated for control information to be allocated to each terminal  200  on a dedicated basis, common region assignment information is generated for common control information that is common for all terminals  200 . 
         [0048]    Also, while downlink assignment control information for given terminal  200  is allocated to all of a plurality of downlink component bands composing the component band group set for that terminal  200 , control section  101  allocates uplink assignment control information for that terminal  200  only to part of the plurality of downlink component bands. The allocation target downlink component band where uplink assignment control information is allocated is “basic component band,” and information related to this basic component band is the above mentioned “basic component band information.” This basic component band information is reported to a given terminal in advance. If this basic component band information is common between given terminals  200 , information may be included in BCH in SCH/BCH generating section  107  and broadcast. 
         [0049]    To information size adjusting section  103 , control section  101  outputs information size comparing information showing the difference in size between the information size of downlink assignment control information determined from the bandwidth of the basic component band and the information size of uplink assignment control information determined from the bandwidth of the uplink component band associated with the downlink component band. 
         [0050]    PDCCH generating section  102  receives control information and region assignment information generated in control section  101 , and generates a PDCCH signal to be sent in each downlink component band, based on these control information and region assignment information. 
         [0051]    Specifically, PDCCH generating section  102  generates a PDCCH signal as follows. While including both uplink assignment control information and downlink assignment control information in a PDCCH signal to be placed in a downlink component band indicated in basic component band information, PDCCH generating section  102  only includes downlink assignment control information in other downlink component bands. This process of sorting uplink assignment control information and downlink assignment control information is performed based on basic component band information. Also, while mapping common assignment control information to a common region of a PDCCH signal, PDCCH generating section  102  maps dedicated assignment control information to a dedicated region. This process of sorting common assignment control information and dedicated assignment control information is performed based on region assignment information. 
         [0052]    Information size adjusting section  103  receives control information and region assignment information generated in control section  101 . Based on these control information and region assignment information, information size adjusting section  103  adjusts the information size of uplink assignment control information and downlink assignment control information included in a PDCCH signal received from PDCCH generating section  102 . 
         [0053]    Specifically, based on basic component band information, information size adjusting section  103  determines whether a PDCCH signal subject to information size adjustment is to be transmitted in the basic component band or in a different downlink component band. 
         [0054]    In a common region of the first PDCCH signal (that is a PDCCH signal which does not include uplink assignment information) which is sent in a downlink component band other than the basic component band, information size adjusting section  103  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of the target downlink component band in which the first PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band, as a size adjustment reference, and, based on this size adjustment reference, information size adjusting section  103  adjusts the information size of downlink assignment control information. Also, in a dedicated region of the first PDCCH signal, information size adjusting section  103  uses the information size of downlink assignment control information determined from the bandwidth of the target downlink component band in which the first PDCCH signal is sent, as a size adjustment reference, and adjusts the information size of downlink assignment control information based on this size adjustment reference. 
         [0055]    On the other hand, as for the second PDCCH signal (that is a PDCCH signal includes both uplink assignment control information and downlink assignment control information) sent in the basic component band, information size adjusting section  103  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of the target downlink component band in which the second PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of the uplink component band associated with the target downlink component band as a size adjustment reference, and, based on this size adjustment reference, information size adjusting section  103  adjusts the information size of uplink assignment control information and downlink assignment control information. 
         [0056]    To be more specific, information size adjusting section  103  includes a padding section (not shown) to adjust the information size of control information by adding zero information to control information. As for the second PDCCH signal, this padding section adds zero information to the smaller one of the information size of downlink assignment control information and the information size of uplink assignment control information until the information size of downlink assignment control information and the information size of uplink assignment control information have equal information size. To which one of downlink assignment control information and uplink assignment control information zero information is added is decided based on information size comparing information. 
         [0057]    Also, in a common region of the first PDCCH signal, the padding section adds zero information to downlink assignment control information, until it becomes equal to the target information size determined from the larger one of the information size of downlink assignment information determined from the bandwidth of the target downlink component band in which the first PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band. On the other hand, in a dedicated region of the first PDCCH despite which is larger or smaller between the information size of downlink assignment control information determined from the bandwidth of a target downlink component band and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the downlink component band, the padding section adds zero information to downlink assignment control information, until it becomes equal to the target information size determined from the information size of downlink assignment information determined from the bandwidth of a downlink component band in the first PDCCH signal is sent. 
         [0058]    Even if the downlink component band of first terminal  200  and the downlink component band of second terminal  200  overlap, the overlapped downlink component band may be the basic component band for first terminal  200  and may be a component band other than the basic component band for second terminal  200 . 
         [0059]    In this case, while mapping uplink assignment control information and downlink assignment control information to first terminal  200 , the PDCCH signal sent in the overlapped downlink component band maps only downlink assignment control information to second terminal  200 . 
         [0060]    For this reason, the process of mapping uplink assignment control information and downlink assignment control information in PDCCH generating section  102 , and the process of information size adjustment of uplink assignment control information and downlink assignment control information in information size adjusting section  103  are performed for each piece of assignment control information included in the target PDCCH signal based on the reference applied to destination terminal  200 . 
         [0061]    CRC adding section  104  adds a CRC bit to the PDCCH signal subjected to size adjustment in information size adjusting section  103 , and then masks the CRC bit with the terminal ID. However, scheduling information related to a broadcast signal which a plurality of terminals needs to receive is masked by an ID that is set in common between a plurality of terminals. Then, CRC adding section  104  outputs the masked PDCCH signal to modulating section  105 . 
         [0062]    Modulating section  105  modulates a PDCCH signal input from CRC adding section  104 , and outputs the modulated PDCCH signal to multiplexing section  108 . 
         [0063]    Modulating section  106  modulates input transmission data (downlink channel data), and outputs a modulated transmission data signal to multiplexing section  108 . 
         [0064]    SCH/BCH generating section  107  generates a SCH and a BCH, and outputs the generated SCH and BCH to multiplexing section  108 . 
         [0065]    Multiplexing section  108  multiplexes the PDCCH signal input from modulating section  105 , the data signal (that, is a PDSCH signal) input from modulating section  106 , and the SCH and BCH input from SCH/BCH generating section  107 . Based on the terminal ID input from control section  101  and downlink assignment control information associated with the terminal ID, multiplexing section  108  maps a data signal (a PDSCH signal) for terminal  200  associated with the terminal ID, to a downlink component band. 
         [0066]    Also, multiplexing section  108  maps the PDCCH signal input from modulating section  105 , to the dedicated resource region and the common resource region in the resource region allocated for a PDCCH. Specifically, the PDCCH signal associated with a data signal which only a certain terminal should receive, is mapped to the resource associated with the terminal ID of the target terminal in the dedicated resource region, and the PDCCH signal associated with a data signal which a plurality of terminals should receive at once, is mapped to the resource in the common resource region. 
         [0067]    IFFT section  109  converts a multiplex signal into a time waveform, and CP adding section  110  acquires an OFDM signal by adding a CP to this time waveform. 
         [0068]    RF transmission section  111  performs a radio transmission process (such as up-conversion and a digital-to-analog (D/A) conversion) to an OFDM signal input from CP adding section  110 , and transmits the result through an antenna. Then, an OFDM signal including assignment control information is sent. 
         [0069]    RF reception section  112  performs a radio receiving process (such as a down-conversion and an analog-to-digital (A/D) conversion) to a received signal which is received in a receiving band through an antenna, and outputs the received signal to CP removing section  113 . 
         [0070]    CP removing section  113  removes the CP from a received signal, and FFT section  114  converts a received signal, from which the CP is removed, into a frequency domain signal. 
         [0071]    Based on uplink assignment control information input from control section  101 , extracting section  115  extracts uplink channel data from a frequency domain signal input from FFT section  114 , and IDFT (Inverse Discrete Fourier Transform) section  116  converts the extracted signal into a time domain signal and outputs the time domain signal to data reception section  117 . 
         [0072]    Data reception section  117  decodes the time domain signal input from IDFT section  116 . And data reception section  117  outputs decoded uplink channel data as received data. 
         [0073]      FIG. 3  is a block diagram showing the configuration of terminal  200  according to Embodiment 1 of the present invention. In  FIG. 3 , terminal  200  includes RF reception section  201 , CP removing section  202 , FFT section  203 , frame synchronization section  204 , demultiplexing section  205 , broadcast signal reception section  296 , information size determination section  207 , PDCCH reception section  208 , format determination section  209 , PDSCH reception section  210 , modulating section  211 , DFT section  212 , frequency mapping section  213 , IFFT section  214 , CP adding section  215 , and RF transmission section  216 . 
         [0074]    RF reception section  201  performs a radio receiving process (such as a down-conversion and an analog-to-digital (A/D) conversion) to a received signal (in this case, an OFDM signal) which is received in a receiving band through an antenna, and outputs the received signal to CP (Cyclic Prefix) removing section  202 . 
         [0075]    CP removing section  202  removes the CP from a received signal, and FFT (Fast Fourier Transform) section  203  converts a received signal, from which the CP is removed, into a frequency domain signal. This frequency domain signal is output to frame synchronization section  204 . 
         [0076]    While searching a SCH included in a signal input from FFT section  203 , frame synchronization section  204  establishes synchronization (frame synchronization) with base station  100 . Also, frame synchronization section  204  acquires the cell ID associated with the sequence used for a SCH (a SCH sequence). That is, the same process as a normal cell search is performed in frame synchronization section  204 . Frame synchronization section  204  outputs frame synchronization timing information to show a frame synchronization timing, and the signal input from FFT section  203  to demultiplexing section  205 . 
         [0077]    Based on frame synchronization timing information input from frame synchronization section  204 , demultiplexing section  205  demultiplexes the signal input from frame synchronization section  204  into a broadcast signal (that is, a BCH), a control signal (that is, a PDCCH signal), and a data signal (that is, a PDSCH signal). Demultiplexing section  205  receives information related, to a downlink component band from broadcast signal reception section  206 , and based on this information, extracts a PDCCH signal on a per downlink component band basis. 
         [0078]    Broadcast signal reception section  206  reads the contents of a BCH input from demultiplexing section  205 , and acquires information related to the configuration of the downlink band and uplink band of base station  100 . Broadcast signal reception section  206  acquires, for example, the number of uplink component bands, the number of downlink component bands, the identification number and bandwidth of each component band, information associated an uplink component band with a downlink component band, and basic component band information. Broadcast signal reception section  206  outputs acquired BCH information to information size determination section  207 , PDCCH reception section  208 , and format determination section  209 . 
         [0079]    Information size determination section  207  receives a PDCCH signal from demultiplexing section  205 , and determines the basic information size to perform blind detection on this PDCCH signal. This basic information size is determined based on basic component band information, which is received from broadcast signal reception section  206 , and the bandwidth of each component band. 
         [0080]    Specifically, in a common region of a PDCCH signal of a downlink component band other than the basic component band (that is, a common region of a PDCCH signal of a component band which does not include uplink assignment information for terminal  200 ), information size determination section  207  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band in which the PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band, as information size reference, and, in a dedicated region, decides the basic information size based on the information size of downlink assignment control information determined from the bandwidth of the target downlink component band. 
         [0081]    Also, as for a PDCCH signal of the basic component band (that is, a PDCCH signal of a component band includes both uplink assignment information for terminal  200  and downlink assignment information), information size determination section  207  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a target downlink component band in which the PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band as information size reference. 
         [0082]    Information size determination section  207  outputs information related to the determined basic information size, and the PDCCH signal associated with this information to PDCCH reception section  208 . 
         [0083]    PDCCH reception section  208  performs blind detection for a PDCCH signal based on the basic information size decided in information size determination section  207 . 
         [0084]    That is, PDCCH reception section  208  specifies the CRC bit part using the basic information size (payload size) decided in information size determination section  207 . Next, after demasking the specified CRC bit part using the terminal ID of terminal  200  in a dedicated region, PDCCH reception section  208  decides the PDCCH signal as a PDCCH signal transmitted for terminal  200 , if the CRC calculation result is “OK” with respect to the whole PDCCH signal. However, since in a common region there is a possibility that both assignment information for terminal  200  and assignment information to be received by a plurality of terminals (for example, broadcast signal scheduling information) may be sent, in a common region, PDCCH reception section  208  performs both damasking process by the terminal ID of terminal  200  and damasking process by an ID set in common between a plurality of terminals, and executes the CRC calculation. Thus, the PDCCH signal that is decided to be received by terminal  200  is output to format determination section  209 . 
         [0085]    Based on type information of assignment control information included in a PDCCH signal received from PDCCH reception section  208 , format determination section  209  decides whether the format of the PDCCH signal is format 0 or format 1A. When determining on format 0, format determination section  209  outputs uplink assignment control information included in the PDCCH signal, to frequency mapping section  213 . Also, when determining on format 1A, format determination section  209  outputs downlink assignment control information included in the PDCCH signal, to PDSCH reception section  210 . 
         [0086]    Based on downlink assignment control information input from format determination section  209 , PDSCH reception section  210  extracts received data from the PDSCH signal input from demultiplexing section  205 . 
         [0087]    Modulating section  211  modulates transmission data and outputs a resulting modulated signal to DFT (Discrete Fourier Transform) section  212 . 
         [0088]    DFT section  212  converts a modulated signal, which is input from modulating section  211 , into a frequency domain, and outputs a resulting plurality of frequency components to frequency mapping section  213 . 
         [0089]    In accordance with uplink assignment control information input from format determination section  209 , frequency mapping section  213  maps a plurality of frequency components input from DFT section  212 , on a PUSCH placed in an uplink component band. 
         [0090]    IFFT section  214  converts a mapped plurality of frequency components into a time domain waveform, and CP adding section  215  adds a CP to the time domain waveform. 
         [0091]    RF transmission section  216  performs a radio transmission process (such as an up-conversion and a digital-to-analog (D/A) conversion) to a CP added signal, and transmits it through an antenna. 
         [0092]    Next, an operation of base station  100  and terminal  200 , which has the above mentioned configuration, is described.  FIG. 4  is a view for explaining an operation of base station  100  and terminal  200 . 
         [0093]    In  FIG. 4 , one uplink component band UB 1  is associated with two downlink component bands DB 1  and DB 2  as a component band group for first terminal  200 . In  FIG. 4 , the bandwidth of UB 1  and DB 1  are 20 MHz and the bandwidth of DB 2  is 10 MHz. DB  1  is defined as a basic component band for first terminal  200  here. 
         [0094]    Base station  100  determines uplink component band UB 1  as uplink channel resource to first terminal  200 , and downlink component bands DB 1  and DB 2  as downlink channel resource. 
         [0095]    Then, base station  100  includes uplink assignment control information and downlink assignment control information into the PDCCH signal, and transmits them to terminal  200 . 
         [0096]    However, base station  100  does not transmit uplink assignment control information for first terminal  200  in all downlink component bands allocated to first terminal  200 , and base station  100  transmits uplink assignment control information only in part of the downlink component bands. On the other hand, base station  100  transmits downlink resource assignment information in all downlink component bands allocated to first terminal  200 . 
         [0097]    In the case of  FIG. 4 , since DB 1  is the basic component band for first terminal  200 , a PDCCH signal to be sent in DB 1  includes both uplink assignment control information and downlink assignment control information. On the other hand, a PDCCH signal to be sent in DB 2  includes downlink assignment control information only. The arrow from a PDCCH towards uplink data (UL Data) shows that uplink assignment control information is sent in the PDCCH. Also, the arrow from a PDCCH towards downlink data (DL Data) or towards a D-BCH shows that downlink assignment control information is sent in the PDCCH. 
         [0098]    Also, the information size of a PDCCH signal is adjusted if necessary. In information size adjusting section  103 , this information size adjustment is performed for a PDCCH signal (that is, a PDCCH signal of the basic component band) of a component band including both uplink assignment control information and downlink assignment control information, and for downlink assignment control information included in a common region of a PDCCH signal sent in a band other than a basic component band. Specifically, as for a basic component band, information size adjusting section  103  adds zero information to the smaller one of the information size of downlink assignment control information and the information size of uplink assignment control information until the information size of downlink assignment control information and the information size of uplink assignment control information have equal information size. Also, as for downlink assignment control information included in a common region of the PDCCH signal sent with a downlink component band other than the basic component band, information size adjusting section  103  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band in which the first PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band as a size adjustment reference, and, adjusts the information size. 
         [0099]    On the other hand, the size of downlink assignment control information included in a dedicated region of a PDCCH signal sent by component band other than a basic component band is decided only from the bandwidth of a downlink component band which sends downlink assignment control information. 
         [0100]    Here, the method of determining size adjustment reference of downlink assignment control information will be described in detail. 
         [0101]      FIG. 5  through  FIG. 8  is a diagram showing the method of determining size adjustment reference of downlink assignment control information. 
         [0102]    At first, a case will be described where a component band group shown in  FIG. 5  is allocated to first through third terminal  200  (in  FIG. 6 , shown as UE A, UE B, and UE C). In  FIG. 5 , a component band group is composed of a downlink component band (band A) of a 20 MHz bandwidth, a downlink component band (band B) of a 10 MHz bandwidth, and an uplink component band of a 15 MHz bandwidth. 
         [0103]      FIG. 6  shows a component band type for each band (that is, information illustrates whether a basic component band (a band where uplink assignment control information (UL grant) is sent) or a component band other than the basic component band) and size adjustment reference in each bandwidth of a dedicated region and a common region for each UE. 
         [0104]    As shown in  FIG. 6 , band A is a basic component band for UE A. Also, band B is a basic component band for UE B. Also, both band A and B are a basic component band for UE C. 
         [0105]    What has to be focused on here is the size adjustment reference in a dedicated region in band B for UE A. As mentioned above, in a dedicated region of the downlink component band other than a basic component band, despite which is larger or smaller between the information size of downlink assignment control information determined from the bandwidth of a target downlink component band and the information size of uplink assignment control information determined from the bandwidth of a uplink component band associated with the downlink component band, the information size of downlink assignment control information determined from the bandwidth of a target downlink component band is used as a size adjustment reference. That is, unlike a basic component band, which always uses the larger one of the information size of uplink assignment control information and downlink assignment control information determined from the bandwidth, as a size adjustment reference, in a dedicated region of a downlink component band other than a basic component band, even if the information size of downlink assignment control information determined from a downlink bandwidth is smaller than the information size of uplink assignment control information determined from a uplink component bandwidth, the information size of downlink assignment control information determined from the bandwidth of a downlink component band, is used as a size adjustment reference. In this case, it is not necessary to perform size adjustment by zero padding to downlink assignment control information, it is possible to prevent the quality of downlink assignment control information from being deteriorated. 
         [0106]    On the other hand, in a common region, it is required to use the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band and the information size of uplink assignment control information determined from the bandwidth of a uplink component band associated with the target downlink component band, as a size adjustment reference. This is because a case might occur where a downlink component band is not the basic component for one terminal  200  but is the basic component band for another terminal  200 , and, in a common region, a control signal, associated with a downlink data signal to be received by a plurality of terminals at once, is transmitted. Thus, considering a certain terminal  200  alone, in a common region of a downlink component band other than a basic component band, as in a dedicated region, the information size of downlink assignment control information determined from the bandwidth of a downlink component band can be used as a size adjustment reference. However, since it is a basic component band for another terminal  200 , in this basic downlink component band, uplink assignment control information, which is necessary for other terminal  200 , may be transmitted in addition to a control signal associated with a data signal, which a plurality of terminals should receive at once. Thus, to let all terminals  200  successfully receive a control signal associated with a downlink signal which should be received at once, and to let all terminals  200  successfully receive uplink assignment control information, in a common region, the same selection reference of size adjustment reference as a basic component band is used, that the larger one of the information size of uplink assignment control information and the information size of downlink assignment control information determined from the bandwidth is used as a size adjustment reference. 
         [0107]    Next, a case will be described where a component band group shown in  FIG. 7  is allocated to first through third terminal  200  (in  FIG. 8 , shown as UE A, UE B, and UE C). In  FIG. 7 , a component band group is composed of a downlink component band (band A) of a 15 MHz bandwidth, a downlink component band (band B) of a 10 MHz bandwidth, and an uplink component band of a 20 MHz bandwidth. 
         [0108]      FIG. 8  shows for each UE a component band type of each band and a size adjustment reference in a dedicated region and a common region of each band. 
         [0109]    What has to be focused on here is the size adjustment reference in a dedicated region of band B for UE A and in a dedicated region of band A for UE B. That is, in a dedicated region of a downlink component band other than a basic component hand, the information size of downlink assignment control information determined from the bandwidth of a downlink component band, is used as a size adjustment reference, so that a component band group shown in  FIG. 7  always uses not the information size of uplink assignment control information determined from a uplink component band, but the information size of downlink assignment control information determined from the bandwidth of a downlink component band having narrow bandwidth. In this case, it is not necessary to perform size adjustment by zero padding to downlink assignment control information, it is possible to prevent the quality of downlink assignment control information from being deteriorated. 
         [0110]    A PDCCH signal, mapping process of assignment control information and information size adjustment process are performed as mentioned above, are received by terminal  200 . 
         [0111]    In terminal  200 , information size determination section  207  decides a basic information size onto performing a blind detection on a received PDCCH signal. This basic information size is determined based on basic component band information received from broadcast signal reception section  206 , and the bandwidth of each component band. 
         [0112]    Specifically, in a common region of a PDCCH signal of a downlink component band other than the basic component band (that is, a common region of a PDCCH signal which does not include uplink assignment information for terminal  200 ), information size determination section  207  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a target downlink component band in which the PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band as a size adjustment reference, and, on the other hand, in a dedicated region, decides the basic information size based on the information size of downlink assignment control information determined from the bandwidth of the target downlink component hand. 
         [0113]    Also, as for a PDCCH signal of the basic component band (that is, a PDCCH signal includes both uplink assignment information and downlink assignment information for terminal  200 ), information size determination section  207  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a target downlink component band in which the PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band as a size adjustment reference. 
         [0114]    Then, PDCCH reception section  208  performs blind detection on a PDCCH signal based on a basic information size determined by information size determination section  207 . 
         [0115]    That is, PDCCH reception section  208  specifies the CRC bit part included in a PDCCH signal according to a basic information size. Although the difference between basic information sizes makes locations of CRC bit parts in PDCCH signals different, PDCCH reception section  208  can specify a CRC bit part of a PDCCH signal sent from each region, by receiving information of a basic information size in a dedicated region and a common region of each downlink component band determined in information size determination section  207 . 
         [0116]    Next, after demasking the specified CRC bit part determined by the terminal ID of terminal  200  or by a common ID among a plurality of terminals, PDCCH reception section  208  decides the PDCCH signal as a PDCCH signal transmitted for terminal  200  if CRC calculation result is “OK” with respect to the whole PDCCH signal. 
         [0117]    Also, based on type information of resource assignment information included in a PDCCH signal received from PDCCH reception section  208 , format determination section  209  decides whether the format of the PDCCH signal is format 0 or format 1A. 
         [0118]    According to the above explanation, a PDCCH signal received in a dedicated region of a downlink component band other than a basic component band is always a downlink allocation signal, so that the type information of resource assignment information is always supposed to indicate downlink assignment control information. That is, the parts associated with the type information of resource assignment information can be used like a parity bit, or can be used to transmit other kinds of information. 
         [0119]    Although in the above description it has been shown that base station  100  reports basic component band information to terminal  200  separately, but, when the uplink component band and downlink component band are not symmetric, for example, the technical specification can define that the downlink component band having low frequency as “basic component band.” That is, the method of reporting “basic component band” is not limited specifically. 
         [0120]    Although in the above description it has been shown that the number of uplink component bands and the number of downlink component bands that a base station supports are not symmetric, the present embodiment is not limited to this. That is, even if the number of uplink component bands and the number of downlink component bands that a base station supports are symmetric, the present embodiment can be applied if the number of component bands allocated to each terminal (that is, instructed by a base station to receive) is asymmetric in the uplink and downlink. 
         [0121]    The present embodiment limits allocating a PDCCH signal including uplink assignment control information to part of downlink component band, and by this means reduces the possibility of performing zero padding to downlink assignment control information that is higher significance. 
         [0122]    Also, a PDCCH signal of a downlink component band other than the basic component band includes downlink resource assignment information alone. Then, in a dedicated region of the downlink component band other than the basic component band, the information size of downlink assignment control information determined from the bandwidth of a downlink component band is always used as a size adjustment reference, so that there is no need to perform information size adjustment. It is not necessary to perform zero padding to downlink assignment control information, it is possible to prevent the quality of downlink assignment control information from being deteriorated. Similarly, as for uplink assignment control information, the number and frequency of padding can be minimized. 
         [0123]    However, in a common region of a downlink component band other than the basic component band, the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band, is used as a size adjustment reference. Therefore, even if different basic component bands are applied to each terminal  200 , terminal  200  on the receiving side can transmit downlink assignment control information without problem. 
         [0124]    According to the above explanation, in a downlink component band other than the basic component band, neither a dedicated region nor a common region transmits uplink assignment control information to given terminal  200 . However, the present invention is not limited to this, and it is equally possible to transmit uplink assignment control information in a common region, even in a downlink component band other than the basic component band. Therefore, in a common region, the selection reference of a size adjustment reference is the same as the selection reference of the basic component band, so that as in the basic component band, it is possible to match the information size between uplink assignment control information and downlink assignment control information. By this means, it is possible to enhance flexibility of the scheduler in base station  100  without increasing the number of blind detection in terminal  200 . 
         [0125]    That is, PDCCH generating section  102  includes downlink assignment control information for given terminal  200 , in a common region and a dedicated region of all channel signals to be sent in a downlink band allocated to target terminal  200 , includes uplink assignment control information to be sent to arbitrary terminal  200 , and on the other hand includes only to some part of the channel signal in a dedicated region, to at least part of the channel signal in a common region. In a common region of all channel signals of a downlink component band allocated to target terminal  200 , information size adjusting section  103  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band where the channel signal having the target common region is transmitted, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band, as a size adjustment reference. In a dedicated region including uplink allocated control information to for target terminal  200 , information size adjusting section  103  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band in which a channel signal having a dedicated region is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band, as a reference of size adjustment. In a dedicated region which does not include uplink allocated control information for target terminal  200 , information size adjusting section  103  uses the information size of downlink assignment control information determined from the bandwidth of a downlink component band in which a channel signal having a dedicated region is sent, as a size adjustment reference. 
       Embodiment 2 
       [0126]    As Embodiment 1, the present embodiment explains the configuration, when the communication bandwidth (the number of basic component band) is asymmetric between an uplink and a downlink, in a common region, an LIE-A system specific broadcast information (D-BCH+) (that is, an LTE terminal does not need to receive) and broadcast information of an LTE system (D-BCH) are transmitted one after another by time division. 
         [0127]      FIG. 9  is a block diagram showing the configuration of base station  300  of Embodiment 2 of the present invention. Compared to base station  100  of Embodiment 1 shown in  FIG. 2 , base station  300  shown in  FIG. 9  adds BCH+ generating section  318  and includes control section  301  instead of control section  101 , information size adjusting section  303  instead of information size adjusting section  103 , and multiplexing section  308  instead of multiplexing section  108 . Parts in  FIG. 9  that are the same as in  FIG. 2  will be assigned the same reference numerals as in  FIG. 2  and overlapping descriptions will be omitted. 
         [0128]    As control section  101 , control section  301  generates control information (including uplink assignment control information and downlink assignment control information), region assignment information showing each pieces of control information indicating whether each control information should be allocated to a dedicated region or a common region, and BCH/BCH+ timing information. Also, control information and region assignment information include the same information as in embodiment 1. 
         [0129]    Also, control section  301  allocates downlink assignment control information for given terminal  400  to all of a plurality of downlink component bands that form a component band group set for this terminal  400 , and on the other hand, allocates uplink assignment control information for given terminal  400  only to part of the plurality of is downlink component bands. Here, as embodiment 1, an allocation target downlink component band where uplink assignment control information is allocated is “basic component band,” and information related to this basic component band is above mentioned “basic component band information.” 
         [0130]    Also, control section  301  outputs information size comparing information, showing the difference between the information size of downlink assignment control information determined from the bandwidth of a basic component band, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the downlink component band, and BCH/BCH+ timing information, to information size adjusting section  303  and multiplexing section  308 . Also, BCH/BCH+ timing information is shared with all terminals  400  in advance. 
         [0131]    As Embodiment 1, control section  301  outputs generated control information and region assignment information to PDCCH generating section  102 , outputs uplink assignment control information to extracting section  115 , and outputs terminal ID and common ID to CRC adding section  104 . 
         [0132]    Information size adjusting section  303  receives control information generated in control section  301 , region assignment information, and BCH/BCH+ timing information. Based on these control information, region assignment information, and BCH/BCH+ timing information, information size adjusting section  303  adjusts the information size of uplink assignment control information and downlink assignment control information included in a PDCCH signal received from PDCCH generating section  102 . 
         [0133]    Specifically, based on basic component band information, information size adjusting section  303  determines whether a PDCCH signal subject to information size adjustment should be transmitted in the basic component band or in a different downlink component band. 
         [0134]    Then, as for a common region of the first PDCCH signal (that is, a PDCCH signal which does not include uplink assignment information) to be sent in a downlink component band other than the basic component band, in the subframe where a BCH for an LTE terminal should be transmitted in a downlink component band other than the basic component band, information size adjusting section  303  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band in which the first PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band as information size adjustment, and, based on this size adjustment reference, adjusts the information size of downlink assignment control information. Also, as for a common region of the first PDCCH signal, in the subframe where a BCH+ for an LTE-A terminal should be transmitted in a downlink component band other than the basic component band, information size adjusting section  303  uses the information size of downlink assignment control information determined from the bandwidth of a target downlink component band in which the first PDCCH signal is sent, and based on this size adjustment reference, adjusts the information size of downlink assignment control information. 
         [0135]    Also, in a dedicated region of the first PDCCH signal, information size adjusting section  303  uses the information size of downlink assignment control information determined from the bandwidth of a target downlink component band in which the first PDCCH signal is sent, as a size adjustment reference, and based on this size adjustment reference, adjusts the information size of downlink assignment control information. 
         [0136]    On the other hand, as for the second PDCCH signal (that is a PDCCH signal includes both uplink assignment control information and downlink assignment control information) to be sent in the basic component band, information size adjusting section  303  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band in which the second PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band as size adjustment reference, and, based on this size adjustment reference, adjusts the information size of uplink assignment control information and downlink assignment control information. 
         [0137]    To be more specific, as in embodiment 1, information size adjusting section  303  includes a padding section (not shown) to adjust the information size of control information by adding zero information to control information. 
         [0138]    BCH+ generating section  318  generates BCH+ being broadcast information for an LTE-A terminal, and outputs generated BCH+ to multiplexing section  308 . 
         [0139]    Multiplexing section  308  multiplexes the PDCCH signal input from modulating section  105 , the data signal (that is, a PDSCH signal) input from modulating section  106 , the SCH and BCH input from SCH/BCH generating section  107 , and BCH+ input from BCH+ generating section  318 . Based on the terminal. ID input from control section  301  and downlink assignment control information associated with the terminal ID, multiplexing section  308  maps a data signal (a PDSCH signal) for terminal  400  associated with the terminal ID, to a downlink component band. 
         [0140]    Also, multiplexing section  308  maps the PDCCH signal input from modulating section  105 , to the dedicated resource region and the common resource region in the resource region allocated for a PDCCH. Specifically, the PDCCH signal associated with a data signal which only a certain terminal should receive, is mapped to the resource associated with the terminal ID of the target terminal in a dedicated resource region, and the PDCCH signal associated with a data signal which a plurality of terminals should receive at once, is mapped to the resource in the common resource region. 
         [0141]    Also, based on BCH/BCH+ timing information input from control section  301 , multiplexing section  308  multiplexes BCH with PDSCH and PDCCH at the timing BCH should be transmitted, and multiplexes BCH+ with PDSCH and PDCCH at the timing BCH+ should be transmitted. That is, BCH and BCH+ are multiplexed by time division. 
         [0142]      FIG. 10  is a block diagram showing the configuration of terminal  400  according to embodiment 2 of the present invention. Compared to terminal  200  of Embodiment 1 shown in  FIG. 3 , terminal  400  shown in  FIG. 10  includes demultiplexing section  405  instead of demultiplexing section  205 , broadcast signal reception section  406  instead of broadcast signal reception section  206 , and information size determination section  407  instead of information size determination section  207 . Also, parts in  FIG. 10  that are, the same as in  FIG. 3  will be assigned the same reference numerals as in  FIG. 3  and overlapping descriptions will be omitted. 
         [0143]    Based on frame synchronization timing information input from frame synchronization section  204 , demultiplexing section  405  demultiplexes the signal input from frame synchronization section  204  into broadcast signal (that is, a BCH and a BCH+), a control signal (that is, a PDCCH signal), and a data signal (that is, a PDSCH signal). Demultiplexing section  405  receives information related to a downlink component band from broadcast signal reception section  406 , and based on this information, extracts PDCCH signals on a per downlink component band basis. Also, demultiplexing section  405  holds BCH/BCH+ timing information which is shared between all terminals  400  in advance by means of reporting from base station  300 , and demultiplexes BCH and BCH+ from a signal input from frame synchronization section  204  based on this timing information. 
         [0144]    Broadcast signal reception section  406  reads the contents of BCH and BCH+ input from demultiplexing section  405 , and as Embodiment 1 receives information related to the configuration of the downlink band and uplink band of base station  300 . Broadcast signal reception section  406  acquires, for example, the number of uplink component bands, the number of downlink component bands, the identification number and bandwidth of each component band, information associated an uplink component band with a downlink component band, and basic component band information. Broadcast signal reception section  406  outputs acquired BCH and BCH+ information to information size determination section  407 , PDCCH reception section  208 , and format determination section  209 . 
         [0145]    Information size determination section  407  receives a PDCCH signal and BCH/BCH+ timing information from demultiplexing section  405 , and determines the basic information size to perform blind detection on this PDCCH signal. This basic information size is determined based on basic component band information, which is received from broadcast signal reception section  406 , the bandwidth of each component band, and BCH/BCH+ timing information. 
         [0146]    Specifically, as for a common region of a PDCCH signal of a downlink component band other than the basic component band (that is a common region of a PDCCH signal of a component band which does not include uplink assignment information for terminal  200 ), in the subframe where a BCH for an LTE terminal should be transmitted in the target downlink component band, information size determination section  407  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a downlink component band in which the PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band, as size adjustment reference, and, as for a common region of a PDCCH signal of a downlink component band other than the basic component band, in the subframe where a BCH+ for an LTE-A terminal should be transmitted in the target downlink component band, decides the basic information size based on the information size of downlink assignment control information determined from the bandwidth of the target downlink component band. 
         [0147]    Also, in a dedicated region of a PDCCH signal of a downlink component band other than the basic component band, information size determination section  407  decides the basic information size based on the information size of downlink assignment control information decided from the bandwidth of the target downlink component band. 
         [0148]    Also, as for a PDCCH signal of the basic component band (that is, a PDCCH signal includes both uplink assignment information and downlink assignment information for terminal  200 ), information size determination section  407  uses the larger one of the information size of downlink assignment control information determined from the bandwidth of a target downlink component band in which the PDCCH signal is sent, and the information size of uplink assignment control information determined from the bandwidth of an uplink component band associated with the target downlink component band as a size adjustment reference. 
         [0149]    Information size determination section  407  outputs information about the decided basic information size and the PDCCH signal associated with this information to PDCCH reception section  208 . 
         [0150]    Next, operation of base station  300  and terminal  400  employing the above mentioned configuration will be explained with reference of  FIG. 4  and  FIG. 10 .  FIG. 4  is a conceptual diagram showing the timing a BCH for an LTE terminal is transmitted in the right downlink component band of base station  300 , and  FIG. 11  is a conceptual diagram of a control signal at the timing a BCH+ for an LTE-A terminal is transmitted in the right downlink component band of base station  300 . 
         [0151]    Differences between  FIG. 11  and  FIG. 4  include whether scheduling information of (D−) BCH will be transmitted in Format 1A, in which transmission uses a PDCCH in a common region, or whether scheduling information of (D−) BCH+ will be transmitted, and the difference between the sizes of Format 1A. That is,  FIG. 4  shows the first subframe where (D−) BCH scheduling information is transmitted,  FIG. 11  shows the second subframe where (D−) BCH+ scheduling information is transmitted. As mentioned above, as for a common region of a PDCCH signal of a downlink component band other than the basic component band, in the subframe where a BCH+ for an LTE-A terminal should be transmitted in the target downlink component band, base station  300  and terminal  400  determine the basic information size based on the information size of downlink assignment control information determined from the bandwidth of a target downlink component band, and, by this means, even if the uplink bandwidth is wider than the bandwidth of a target downlink component band, do not perform a padding for Formal 1A. Therefore, in a common region, it is possible to avoid unnecessary padding for Format 1A. However, at the point when a BCH for an LTE is transmitted in the target downlink component band, to perform the same padding process as for an LTE terminal, backward compatibility can be kept. 
         [0152]    Embodiments of the present invention have been described above. 
         [0153]    Also, with the above embodiments, the relationship between a downlink component band and an uplink component band has been reported by a BCH from a base station. However, until a terminal receives (part of BCHs) a BCH showing the relationship with an uplink component band, a terminal cannot calculate the information size of Format 1A that should be determined by taking into account both the bandwidth of a downlink component band and the bandwidth of an uplink component band. For this reason, when the bandwidth of an uplink component band is unknown on the terminal side, the information size of Format 1A will be calculated on the premise that the bandwidth of the known downlink component band and the bandwidth of the unknown uplink component band are the same. 
         [0154]    However, in this case, depending on the relationship between the actual frequency bandwidth of an uplink component band and the frequency bandwidth of a downlink component band, the size of Format 1A a base station actually uses, and the size of Format 1A assumed before a terminal receives information of an uplink component band, may differ. To avoid this problem, only scheduling information for a special BCH for reporting a frequency location or a frequency bandwidth of an uplink component band can be transmitted in a special format other than Format 1A. 
         [0155]    Each embodiment mentioned above explains an example when the present invention is performed by hardware, but the present invention can be implemented with software. 
         [0156]    Furthermore, each function block employed in the description of each of the aforementioned embodiments may typically be implemented as an LSI constituted by an integrated circuit. These may be individual chips or partially or totally contained on a single chip. “LSI” is adopted here but this may also be referred to as “IC,” “system LSI,” “super LSI,” or “ultra LSI” depending on differing extents of integration. 
         [0157]    Further, the method of circuit integration is not limited to LSI&#39;s, and implementation using dedicated circuitry or general purpose processors is also possible. After LSI manufacture, utilization of an FPGA (Field Programmable Gate Array) or a reconfigurable processor where connections and settings of circuit cells in an LSI can be regenerated is also possible. 
         [0158]    Further, if integrated circuit technology comes out to replace LSI&#39;s as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Application of biotechnology is also possible. 
         [0159]    The disclosures of Japanese Patent Application No. 2008-306742, filed on Dec. 1, 2008, and Japanese Patent Application No. 2009-079674, filed on Mar. 27, 2009, including the specifications, drawings and abstracts, are incorporated herein by reference in their entirety. 
       INDUSTRIAL APPLICABILITY 
       [0160]    The radio terminal, radio base station, channel signal forming method and channel signal receiving method of the present invention are useful to prevent the quality of downlink assignment control information from degrading.