JP2011166808A - Mobile station and radio base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To limit the number of DL (downlink) carries for detecting PDCCH (physical downlink control channel) by a mobile station UE in performing CA (carrier aggregation). <P>SOLUTION: A mobile station UE is equipped with an RACH (random access channel) procedure section 12 configured to attempt to detect an RA response for an RA preamble only by the DL carrier corresponding to a UL carrier from a plurality of DL carriers in performing CA and when the UL carrier transmits the RA preamble. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mobile station and a radio base station.

  In the FDD system of LTE (Long Term Evolution), one DL (Downlink) carrier and one UL (Uplink) carrier form a pair. An LTE mobile communication system can be operated using a plurality of DL carriers and UL carriers, but the correspondence between DL carriers and UL carriers is one-to-one.

  As shown in FIG. 5, the mobile station UE is configured to use only one DL carrier and UL carrier pair at a temporary point where communication is performed with the radio base station eNB via a radio link. ing.

  The mobile station UE in the IDLE (standby) state is configured to select a DL carrier to wait according to a cell selection operation defined in TS36.304 of 3GPP.

  The mobile station UE is configured to identify the UL carrier that is paired with the DL carrier from broadcast information (specifically, SIB2) in the DL carrier that is waiting.

  Here, when the mobile station UE transits from the IDLE state to the CONNECTED (connected) state, the mobile station UE is configured to establish a radio link with the waiting DL carrier and the UL carrier paired with the DL carrier. Has been.

  The radio base station eNB transmits a layer 3 (RRC: Radio Resource Control) message for each mobile station UE to the CONNECTED mobile station UE at a predetermined timing, thereby establishing a DL carrier and UL for establishing a radio link. The carrier pair can be changed.

  In the LTE system, a RACH procedure (RACH Procedure) terminated at the layer 1 / MAC sublayer is defined. When the mobile station UE starts the RACH procedure, the mobile station UE transmits an RA preamble (RA preamble) to the radio base station eNB on the uplink, and the radio base station eNB that detects the RA preamble transmits the RA preamble on the downlink. After transmitting the response (RA response), the mobile station UE attempts to detect the RA response after transmitting the RA preamble (see Non-Patent Documents 2 and 3).

  As shown in FIG. 6, the mobile station UE transmits an RA preamble using a DL carrier that is waiting or is paired with a connected DL carrier, and is waiting for the DL. Attempt to detect RA response on carrier or connected DL carrier.

  In addition, as illustrated in FIG. 6, when the radio base station eNB detects the RA preamble, the radio base station eNB transmits an RA response on the DL carrier that is paired with the UL carrier that has detected the RA preamble.

  Also, as shown in FIG. 7, the broadcast information (SIB2) in the DL carrier includes “PRACH (Physical Random Access Channel) configuration (frequency / time resource for RA preamble)” in the UL carrier paired with the DL carrier. The mobile station UE is configured to transmit the RA preamble using the frequency / time resource specified by the “PRACH configuration”.

  There are 64 “preamble sequences” with different “cyclic shifts” in the RA preamble, and 64 RA preambles are systematically used in one frequency / time resource of the PRACH. Can be multiplexed.

  Further, the system can be used by classifying 64 preamble sequences into a preamble sequence for contention and a preamble sequence for contention free.

  The preamble sequence for Contention is a preamble sequence that can be selected when the mobile station UE selects a preamble sequence to be transmitted as an RA preamble, and the preamble sequence for Content free This is a preamble sequence that cannot be selected when selecting a preamble sequence to be transmitted, but is transmitted as an RA preamble when a preamble sequence is individually assigned from the radio base station eNB.

  In addition, the allocation of the preamble sequence for the content free is performed by a PDCCH (Physical Downlink Control Channel) or an RRC message.

  Here, as shown in FIG. 8, since the range of the preamble sequence for Contention among the 64 preamble sequences is included in the broadcast information (SIB2) in the DL carrier, the mobile station UE uses the preamble for Contention. A sequence and a preamble sequence for content free can be distinguished.

  If the detected RA preamble is a preamble sequence for Contention free, since the radio base station eNB assigns the preamble sequence to the mobile station UE individually, the RA response is already transmitted when the RA response is transmitted. Can be specified.

  On the other hand, if the detected RA preamble is a preamble sequence for Contention, since it is the preamble sequence selected by the mobile station UE, the radio base station eNB still determines which mobile station at the time of transmitting the RA response. It cannot be specified whether the RA response should be transmitted to the UE.

  A resource on PDSCH (Physical Downlink Shared Channel) that transmits an RA response is specified by PDCCH that is CRC-masked by RA-RNTI (Random Access-Radio Network Temporary Identifier).

  Therefore, the mobile station UE that has transmitted the RA preamble attempts to detect the PDCCH that is CRC masked by the RA-RNTI in order to detect the RA response.

  As shown in FIG. 9, the resource for detecting the PDCCH is called “search space”, and the radio base station eNB is a “common search space (Common) that is fixed in the system among the search spaces. Search Space) ”is to transmit the PDCCH that is CRC-masked by RA-RNTI.

  A search space other than the common search space may be used as a “mobile specific search space (UE Specific Search Space)” for transmitting a PDCCH in which “UL grant” or “DL assignment” is individually assigned to each mobile station UE. Is possible.

  Here, since the common search space is small, there is a problem that the PDCCH resource shortage is relatively likely to occur in the common search space.

  If the PDCCH resource on the common search space is filled, the radio base station eNB cannot transmit the RA response, and the completion of the RACH procedure is delayed.

  In addition, as other PDCCH transmitted on a common search space, PDCCH (PDCCH that is CRC-masked by SI-RNTI) for notifying resource allocation of broadcast information or PDCCH (PDCCH for notifying resource allocation of Paging (incoming) message) PDCCH CRC-masked with P-RNTI).

  On the other hand, for the purpose of further improving the frequency use efficiency from the LTE system, improving the peak throughput, and shortening the transmission delay, the examination and specification of the LTE-A system are currently underway in 3GPP.

  As a main function of the LTE-A scheme, “CA: Carrier Aggregation” that improves user throughput by setting a plurality of DL carriers and UL carriers at the same time for one mobile station UE and performing communication is provided. (See Non-Patent Documents 2 and 4).

  Note that the LTE-A scheme has been studied so that it can be operated as the same system while maintaining backward compatibility with the LTE scheme. As shown in FIG. The DL carrier is paired with the UL carrier specified from the broadcast information (SIB2) in the DL carrier.

  As a CA scenario, a scenario in which the number of DL carriers simultaneously used in the mobile station UE and the number of UL carriers are asymmetric is also being studied.

  In particular, since there are generally more DLs than UL as user data traffic, the number of DL carriers provided as a system or the number of DL carriers supported as an implementation of the mobile station UE is larger than the number of UL carriers. The scenario is emphasized.

  In this case, since the number of DL carriers is larger than the number of UL carriers, as shown in FIG. 11, the correspondence relationship between DL carriers and UL carriers specified from broadcast information (SIB2) in DL carriers is also 1: 1. In addition to the operation of only the corresponding relationship, the operation as the N-to-1 correspondence relationship is also assumed.

3GPP TS36.304 3GPP TS36.300 3GPP TS36.321 3GPP TS 36.912

  As described above, when a CA scenario in which the number of DL carriers is larger than the number of UL carriers is assumed, in order to reduce the problem of insufficient PDCCH resources on the common search space described above, a system for transmitting RA responses is preferably used. It is desirable to disperse in a plurality of DL carriers possessed by

  For example, it is desirable to distribute the RA response to the RA preamble transmitted on the UL carrier # 2 in FIG. 11 between the DL carrier # 2 and the DL carrier # 3.

  In addition, when the mobile station UE performing CA needs to detect PDCCH in each DL carrier when receiving on a plurality of DL carriers, the processing capability required for detection and decoding of PDCCH is: There is a problem that the number of DL carriers set in the mobile station UE increases in proportion to the number of DL carriers, leading to an increase in mounting cost of the mobile station UE.

  Therefore, when performing CA, it is desirable to limit the DL carrier on which the mobile station UE detects PDCCH, if possible.

  Therefore, the present invention has been made in view of the above-described problems, and provides a mobile station and a radio base station that can limit DL carriers on which the mobile station UE detects PDCCH when performing CA. For the purpose.

  A first feature of the present invention is a mobile station configured to be able to perform communication using a plurality of carriers having different carrier frequencies with a radio base station, and performs the communication. In this case, when an RA preamble is transmitted on an uplink carrier, an attempt is made to detect an RA response to the RA preamble only from a plurality of downlink carriers on a downlink carrier corresponding to the uplink carrier. The gist of the present invention is to include a RACH procedure part configured as described above.

  A second feature of the present invention is a radio base station, and when an RA preamble is detected using an PRACH resource and a preamble sequence in an uplink carrier, the uplink carrier, the PRACH resource, and the preamble sequence The gist of the present invention is that it comprises a RACH procedure unit configured to transmit an RA response to the RA preamble only on a downlink carrier corresponding to at least one of the above.

  A third feature of the present invention is a radio base station, and a mobile station performing communication using a plurality of carriers having different carrier frequencies with the radio base station, together with an individual RA preamble, The gist of the invention is that the mobile station includes a transmission unit configured to transmit notification information for notifying an uplink carrier to transmit the dedicated RA preamble.

  As described above, according to the present invention, it is possible to provide a mobile station and a radio base station that can limit DL carriers on which the mobile station UE detects PDCCH when performing CA.

It is a figure for demonstrating the mobile communication system which concerns on the 1st Embodiment of this invention. FIG. 3 is a functional block diagram of a mobile station according to the first embodiment of the present invention. FIG. 3 is a functional block diagram of a radio base station according to the first embodiment of the present invention. It is a figure for demonstrating the mobile communication system which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating a general mobile communication system. It is a figure for demonstrating a general mobile communication system. It is a figure for demonstrating a general mobile communication system. It is a figure for demonstrating a general mobile communication system. It is a figure for demonstrating a general mobile communication system. It is a figure for demonstrating a general mobile communication system. It is a figure for demonstrating a general mobile communication system.

(Mobile communication system according to the first embodiment of the present invention)
The configuration of the mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, in the mobile communication system according to the present embodiment, two UL carriers and three DL carriers are provided. And mobile station UE # a which is performing CA and mobile stations UE # b to UE # d which are not performing CA are mixed.

  Further, in each of UL carrier # 1 and UL carrier # 2, resources for transmitting and receiving RA preambles (transmission = mobile station UE, reception = radio base station eNB) are set, and in each corresponding DL carrier It is assumed that the broadcast information (SIB2) includes “PRACH configuration” and “preamble sequence range for contention”.

  Specifically, the DL carrier # 1 broadcasts the “PRACH configuration” of the UL carrier # 1 and the “preamble sequence range for the contention”, and the DL carrier # 2 and the DL carrier # 3 transmit the UL carrier #. 2 "PRACH configuration" and "Range of preamble sequence for contention" are broadcast.

  As shown in FIG. 2, the mobile station UE includes a receiving unit 11 and a RACH procedure unit 12. As shown in FIG. 3, the radio base station eNB includes a transmission unit 21 and a RACH procedure unit 22. It is equipped with.

<Case 1>
First, a case will be described in which the mobile station UE # a transmits an RA preamble for contention (common RA preamble) on the UL carrier # 1.

  In such a case, the radio base station eNB cannot identify which mobile station UE has transmitted the RA preamble at the time when the RA preamble for Contention is detected in the UL carrier # 1.

  That is, in the example of FIG. 1, the radio base station eNB cannot specify which of the mobile station UE # a and the mobile station UE # b has transmitted the RA preamble.

  Even if the mobile station UE # a performing CA attempts to detect the RA response in all of the DL carriers # 1 to # 3, the mobile station UE # b not performing CA performs the DL carrier # 1. Since the radio base station eNB tries to receive the RA response only at the mobile station UE # b, the RA response is received even when the mobile station UE # b that has not performed the CA transmits the RA preamble. In addition, an RA response is transmitted using DL carrier # 1 paired with UL carrier # 1.

  For this reason, when the mobile station UE # a transmits the RA preamble for Contention in the UL carrier # 1, the detection of the RA response is performed by the DL carrier # 2 that is not paired with the UL carrier # 1. The attempt at # 3 is useless, and the mobile station UE # a only needs to detect the RA response only on the DL carrier # 1.

  Specifically, the RACH procedure part 12 of the mobile station UE transmits the RA preamble (the RA preamble for the contention or the RA preamble for the contention free) in the UL carrier # 1 when performing CA. In this case, only the DL carrier # 1 corresponding to the UL carrier # 1 among the plurality of DL carriers # 1 to # 3 is configured to try to detect an RA response to the RA preamble.

  That is, in such a case, the RACH procedure unit 12 of the mobile station UE is configured not to try to detect an RA response in the DL carriers # 2 to # 3.

<Case 2>
Secondly, a case will be described in which the mobile station UE # a transmits an RA preamble for Contention using the UL carrier # 2.

  In such a case, the radio base station eNB cannot identify which mobile station UE has transmitted the RA preamble at the time of detecting the RA preamble for Contention in the UL carrier # 2.

  That is, in the example of FIG. 1, the radio base station eNB cannot specify which of the mobile station UE # a, the mobile station UE # c, or the mobile station UE # d has transmitted the RA preamble.

  Even if the mobile station UE # a performing CA attempts to detect the RA response in all of the DL carriers # 1 to # 3, the radio base station eNB is paired with the UL carrier # 2. Since no RA response is transmitted on a non-DL carrier # 1, it is useless for the mobile station UE #a to detect an RA response on the DL carrier # 1.

  On the other hand, there are two DL carriers # 2 to # 3 that are paired with UL carrier # 2. Here, it is considered that the mobile station UE # c not performing CA uses only DL carrier # 2, and the mobile station UE # d not performing CA uses only DL carrier # 3 Then, as for the radio base station eNB, the RA response is received even if the mobile station UE # a, the mobile station UE # c, or the mobile station UE # d transmits the RA preamble. The RA response needs to be transmitted to both DL carrier # 2 and DL carrier # 3.

  However, since the RA preamble is actually transmitted by any one of the mobile station UE # a, the mobile station UE # c, and the mobile station UE # d, it is not possible to transmit the RA response twice. Therefore, the PDCCH resource on the common search space is wasted.

  Here, as illustrated in FIG. 4, the radio base station eNB divides and manages at least one of the PRACH resource and the RA preamble sequence for Contention in the UL carrier # 2 in two, DL carrier # 2 and DL carrier # 3 Thus, this waste can be avoided by notifying different “PRACH configuration” and “range of preamble sequence for contention” by SIB2.

  In this case, since the mobile station UE # c uses only the DL carrier # 2, the broadcast information (SIB2) in the DL carrier # 2 is transmitted when the RA preamble for Contention is transmitted using the UL carrier # 2. Only the PRACH resources (PRACH time / frequency resources) of the UL carrier # 2 specified in the above and the RA preamble sequence for Contention are applied.

  Similarly, since the mobile station UE # d uses only the DL carrier # 3, the broadcast information (SIB2) in the DL carrier # 3 is transmitted when transmitting the RA preamble for the contention in the UL carrier # 2. Only the PRACH resources (PRACH time / frequency resources) of the UL carrier # 2 specified in the above and the RA preamble sequence for Contention are applied.

  Therefore, even when the radio base station eNB detects the RA preamble for the contention in the UL carrier # 2, the radio base station eNB specifies which DL carrier the mobile station UE transmits the RA preamble for the content according to the broadcast information in which DL carrier. Therefore, the RA response can be transmitted only on such DL carrier.

  Also, in this case, the mobile station UE # a transmits the RA preamble for Contention using the PRACH frequency / time resource and the preamble sequence specified in the broadcast information on the DL carrier # 2 on the UL carrier # 2. In this case, it is useless to attempt the detection of the RA response with the DL carrier # 3, and the mobile station UE #a only needs to detect the RA response only with the DL carrier # 2.

<Case 3>
Thirdly, a case will be described in which the mobile station UE # a transmits an RA preamble (contention RA preamble) for Contention free.

  The radio base station eNB can specify that the mobile station UE # a has transmitted the RA preamble at the time when the RA preamble for Contention free is detected.

  Here, if the mobile station UE # a attempts to detect PDCCH CRC-masked with RA-RNTI on the common search space in order to detect RA responses in all DL carriers # 1 to # 3. The radio base station eNB can transmit an RA response to the RA preamble for the content free from the detected mobile station UE # a anywhere on the DL carriers # 1 to # 3.

  At this time, the radio base station eNB selects the DL carrier used for the transmission of the RA response as the quality of each DL carrier at that time (for example, selects the DL carrier with the smallest propagation loss) and the DL carrier at that time. It can be selected according to the usage status of the PDCCH (for example, the DL carrier having the smallest number of PDCCH transmissions or the DL carrier having the smallest number of PDCCH transmissions on the common search space).

  On the other hand, when the mobile station UE # a tries to detect PDCCH CRC-masked by RA-RNTI in all of the DL carriers # 1 to # 3, the radio base station eNB uses one of the DL carriers. Since only the RA response is transmitted, the mobile station UE # a unnecessarily detects the PDCCH that is CRC-masked with the RA-RNTI on the other two DL carriers, which increases the implementation cost of the mobile station UE. I will.

  Conversely, if the mobile station UE performing CA determines in advance a DL carrier that should wait for an RA response to the RA preamble for Contention free, the mobile station UE performs CRC masking with such useless RA-RNTI. Of detected PDCCH can be avoided.

  Several methods are shown below.

<Method 1>
The radio base station eNB designates the UL carrier (or the UL carrier and PRACH frequency / time resource) in which the RA preamble is detected in the broadcast information (SIB2), as in the case of transmitting the RA preamble for Contention. The RA response may be transmitted only on the DL carrier.

  At this time, the radio base station eNB assigns a content-free RA preamble to the mobile station UE, and at the same time, permits the transmission of the content-free RA preamble, or UL carrier and PRACH frequencies. By notifying the time resource, it is possible to control the RA response transmitted in the system total so that it is distributed to the DL carriers in the system.

  For example, the radio base station eNB uses a content free for the mobile station UE # a such that an RA response to the RA preamble for the content free from the mobile station UE # a is transmitted on the DL carrier # 1. When assigning the RA preamble, UL carrier # 1 is designated.

  In addition, the radio base station eNB transmits an RA response to the RA preamble for the content free from the other mobile station UE # 1 performing CA in the same manner as the mobile station UE # a on the DL carrier # 2. Thus, when allocating the content preamble RA preamble to the mobile station UE # 1, the frequency of the PRACH included in the broadcast information (SIB2) in the UL carrier # 2 and the DL carrier # 2 -Specify the time resource.

  Further, the radio base station eNB transmits an RA response to the RA preamble for the content free from the other mobile station UE # 2 performing CA in the same manner as the mobile station UE # a on the DL carrier # 3. Thus, when allocating the content preamble RA preamble to the mobile station UE # 2, the frequency of the PRACH included in the broadcast information (SIB2) in the UL carrier # 2 and the DL carrier # 3 -Specify the time resource.

  As a result, DL carriers that transmit RA responses can be distributed to a plurality of DL carriers operated in the system.

  Here, as a UL carrier (or UL carrier and PRACH frequency / time resource) permitting transmission of an RA preamble for contention free, the UL carrier (or UL carrier and PRACH frequency / time resource) is used. ) May be notified of information (for example, center frequency information of the DL carrier) specifying the DL carrier that is designated by the broadcast information (SIB2).

<Method 2>
The radio base station eNB may be configured to notify the mobile station UE in advance of the location to transmit the RA response to the RA preamble for Contention free.

  Specifically, the radio base station eNB notifies such information in advance using an RRC message. The timing for transmitting the RRC message to the mobile station UE may be when instructing the use of a plurality of DL carriers or when performing handover while using a plurality of DL carriers.

  The radio base station eNB operates the RA response transmitted in the system total in the system by notifying the DL carrier that transmits the RA response to the RA preamble for the content free specified to the mobile station UE performing CA. It is possible to control to be distributed over a plurality of DL carriers.

  For example, the radio base station eNB notifies the mobile station UE # a that an RA response to the RA preamble for Contention free should be transmitted on the DL carrier # 1, and the mobile station UE # a Similarly, the other mobile station UE # 1 performing CA is notified that the RA response to the RA preamble for the content free should be transmitted by the DL carrier # 2, and the mobile station UE # The other mobile station UE # 2 performing CA as in a may be notified that the RA response to the RA preamble for the content free should be transmitted on the DL carrier # 3. .

  As a result, the transmission of the RA response can be distributed to a plurality of DL carriers operated in the system.

  The characteristics of the present embodiment described above may be expressed as follows.

  A first feature of the present embodiment is a mobile station UE configured to be able to perform communication (CA) using a plurality of carriers having different carrier frequencies with a radio base station eNB, When CA is performed and an RA preamble is transmitted in a UL carrier (uplink carrier), only a DL carrier corresponding to the UL carrier from among a plurality of DL carriers (downlink carriers) The gist is to include a RACH procedure unit 12 configured to try to detect an RA response to such an RA preamble.

  1st characteristic of this embodiment WHEREIN: Even if it has the receiving part 11 comprised so that the above-mentioned DL carrier might receive the alerting | reporting information (SIB2) which designates UL carrier corresponding to this DL carrier Good.

  In the first feature of the present embodiment, when the RACH procedure unit 12 performs CA and transmits the RA preamble using the PRACH resource and the preamble sequence in the UL carrier, the RACH procedure unit 12 It may be configured to attempt to detect the RA response only from the DL carrier corresponding to the UL carrier and at least one of the PRACH resource and the preamble sequence.

  In the first feature of the present embodiment, in the above-described downlink carrier, broadcast information (SIB2) that specifies the UL carrier corresponding to the DL carrier and at least one of the PRACH resource and the preamble sequence is received. You may have comprised the receiving part 11 comprised.

  In the first feature of the present embodiment, the RA preamble described above may be a “Contention RA preamble (common RA preamble)”.

  The second feature of the present embodiment is a radio base station eNB, and when a RA preamble is detected using a PRACH resource and a preamble sequence in a UL carrier, the UL carrier, the PRACH resource, and the preamble sequence The gist is that the RACH procedure unit 22 is configured to transmit an RA response to the RA preamble only on a DL carrier corresponding to at least one.

  In the second feature of the present embodiment, the DL carrier described above is configured to transmit broadcast information (SIB2) designating at least one of the UL carrier corresponding to the downlink carrier and the PRACH resource and the preamble sequence. The transmitter 21 may be provided.

  In the second feature of the present embodiment, the RA preamble described above may be a “Contention RA preamble”.

  The third feature of the present embodiment is the radio base station eNB, and for the mobile station UE performing CA, together with the “contention free RA preamble (individual RA preamble)”, the mobile station UE performs “Contention The gist of the invention is that it includes a transmission unit 21 configured to transmit notification information for notifying a UL carrier to which “free RA preamble” is to be transmitted.

  In the third feature of the present embodiment, the transmission unit 21 may be configured to transmit information specifying a DL carrier that designates the UL carrier by broadcast information as the notification information.

  In the third feature of the present embodiment, the transmission unit 21 notifies the PRACH resource to which the “station preamble free RA preamble” is to be transmitted in the mobile station UE, in addition to the above-described UL carrier, by the above-described notification information. It may be configured.

  In the third feature of the present embodiment, the transmission unit 21 is configured to transmit information specifying the UL carrier and the DL carrier designating the PRACH resource by broadcast information as the notification information described above. May be.

  In the third feature of the present embodiment, the transmission unit 21 may be configured to transmit the notification information described above using an RRC message.

  Note that the operations of the mobile station UE and the radio base station eNB described above may be implemented by hardware, may be implemented by a software module executed by a processor, or may be implemented by a combination of both. .

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the mobile station UE and the radio base station eNB. Moreover, this storage medium and processor may be provided in the mobile station UE and the radio base station eNB as a discrete component.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

UE ... mobile station 11 ... receiving unit 12 ... RACH procedure unit eNB ... radio base station 21 ... transmitting unit 22 ... RACH procedure unit

Claims (1)

A mobile station configured to be able to perform communication using a plurality of carriers having different carrier frequencies with a radio base station,
When the communication is performed and the RA preamble is transmitted on the uplink carrier, the RA for the RA preamble is only selected from the plurality of downlink carriers on the downlink carrier corresponding to the uplink carrier. A mobile station comprising a RACH procedure part configured to attempt to detect a response.