Mobile station and radio base station

Abstract

“Inter-site CA” using CCs under different radio base stations eNB in an asynchronous state can be performed appropriately. A mobile station UE of the present invention comprises a transmission unit 12 configured to transmit “UE Capability Information” to a radio base station eNB, the “UE Capability Information” indicating whether the mobile station UE is capable of performing “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state.

Claims

1. A mobile station that includes a processor coupled to a memory, the mobile station comprising: a transmitter that transmits capability information by UE Capability Information to a radio base station in response to a capability enquiry by UE Capability Enquiry from the radio base station received by a receiver of the mobile station, wherein the capability information includes a field that indicates whether the mobile station is capable of communication using component carriers in an asynchronous state under different radio base stations, the capability information indicates whether the mobile station is capable to cope with a predetermined difference in timing between component carriers under different radio base stations, the transmitter notifies the radio base station of a number of component carriers usable in the communication, and the capability information is associated with a band combination.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an overall configuration diagram of a mobile communication system in a first embodiment of the present invention.

(2) FIG. 2 is a functional block diagram of a mobile station UE in the first embodiment of the present invention.

(3) FIG. 3 is a functional block diagram of a radio base station eNB in the first embodiment of the present invention.

(4) FIG. 4 is a flowchart showing an operation of the mobile station UE in the first embodiment of the present invention.

(5) FIG. 5 is a view for explaining a conventional art.

(6) FIG. 6 is a view for explaining a conventional art.

(7) FIG. 7 is a view for explaining a conventional art.

DETAILED DESCRIPTION

(8) (Mobile Communication System in First Embodiment of Present Invention)

(9) A mobile communication system in a first embodiment of the present invention is described with reference to FIGS. 1 to 4.

(10) As shown in FIG. 1, the mobile communication system in the embodiment is a mobile communication system of LTE Release-12 or beyond and is configured such that “Inter-site CA” using CCs under different radio base stations eNB in an asynchronous state can be applied.

(11) Note that the mobile communication system of the embodiment is configured such that not all of the radio base stations eNB are in a synchronous state.

(12) As shown in FIG. 2, a mobile station UE of the embodiment includes a control unit 11, a transmission unit 12, and a reception unit 13.

(13) The control unit 11 is configured to perform various controls in the mobile station UE such as a control required to perform the “Inter-site CA”, for example.

(14) The transmission unit 12 is configured to transmit various signals to the radio base stations eNB, and the reception unit 13 is configured to receive various signals from the radio base stations eNB.

(15) For example, the transmission unit 12 is configured to transmit “UE Capability Information” to a radio base station eNB when the reception unit 13 receives a “UE Capability Enquiry” from the radio base stations eNB.

(16) In this case, the transmission unit 12 notifies the radio base station eNB whether the control unit 11 can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state, by using this “UE capability Information”.

(17) Note that the transmission unit 12 may be configured to perform such notification by using a signal other than the “UE capability Information”.

(18) Moreover, the transmission unit 12 may be configured to notify the radio base station eNB of the number of the radio base stations eNB which the mobile station UE can use in the “Inter-site CA”.

(19) The transmission unit 12 may be configured to perform such notification by using the “UE capability Information” or by using a signal other than the “UE capability Information”.

(20) Furthermore, the transmission unit 12 may be configured to notify the radio base station eNB of the number of CCs which the mobile station UE can use in the “Inter-site CA”.

(21) The transmission unit 12 may be configured to perform such notification by using the “UE capability Information” or by using a signal other than the “UE capability Information”.

(22) The transmission unit 12 may be configured to notify the radio base station eNB whether the mobile station UE can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state, per unit time.

(23) For example, the transmission unit 12 may be configured as follows. When the mobile station UE can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of subframes, the transmission unit 12 notifies the radio base station eNB that the mobile station UE can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of subframes.

(24) Moreover, the transmission unit 12 may be configured as follows. When the mobile station UE can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of radio frames, the transmission unit 12 notifies the radio base station eNB that the mobile station UE can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of radio frames.

(25) Note that the transmission unit 12 may be configured to notify the radio base station eNB that the mobile station UE can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of subframes but cannot perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of radio frames.

(26) The transmission unit 12 may be configured to perform such notification by using the “UE capability Information” or by using a signal other than the “UE capability Information”.

(27) Moreover, the transmission unit 12 may be configured to transmit the aforementioned “UE Capability Information” for every frequency band, to transmit the aforementioned “UE Capability Information” for every communication functional block, or to transmit the aforementioned “UE Capability Information” for every “CA band combination”.

(28) As shown in FIG. 3, each of the radio base stations eNB in the embodiment includes a reception unit 21, a control unit 22, and a transmission unit 23.

(29) The reception unit 21 is configured to receive various signals from the mobile station UE. The control unit 22 is configured to perform various controls in the radio base station eNB such as a control for performing the “Inter-site CA”, for example. The transmission unit 23 is configured to transmit various signals to the mobile station UE.

(30) For example, the control unit 22 is configured as follows. When the reception unit 21 receives the aforementioned “UE Capability Information” from the mobile station UE, the control unit 22 determines whether cause the mobile station UE to perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state based on the received “UE Capability Information”.

(31) Moreover, the transmission unit 23 is configured to transmit the aforementioned “UE Capability Enquiry” to the mobile station UE.

(32) An operation of the mobile communication system of the embodiment, specifically, the mobile station UE of the embodiment is described with reference to FIG. 4.

(33) The mobile station UE determines whether it can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state.

(34) If “YES”, the operation proceeds to step S102. If “NO”, the operation proceeds to step S103.

(35) In step S102, the mobile station UE notifies the radio base station eNB that the mobile station UE can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state.

(36) Meanwhile, in step S103, the mobile station UE notifies the radio base station eNB that the mobile station UE cannot perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state.

Modified Example 1

(37) The mobile communication system in a modified example 1 of the present invention may be configured such that the radio base stations eNB notify each other of a time unit (for example, a radio frame unit or a subframe unit) applicable to establish synchronization via an X2/S1 interface.

(38) The features of the present embodiment may also be expressed as follows.

(39) A first feature of the present embodiment is summarized as a mobile station UE including a transmission unit 12 configured to transmit “UE Capability Information (capability information)” to a radio base station eNB, the “UE Capability Information” indicating whether the mobile station UE is capable of performing “Inter-site CA (carrier aggregation)” using CCs (component carriers) under different radio base stations eNB in an asynchronous state.

(40) Such a configuration can avoid a situation where the radio base station eNB instructs the mobile station UE, incapable of performing the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state, to perform such “Inter-site CA”.

(41) In the first feature of the embodiment, the transmission unit 12 may notify the radio base station eNB of the number of radio base stations eNB usable in the “Inter-site CA”.

(42) Such a configuration can avoid a situation where the radio base station eNB instructs the mobile station UE to perform the “Inter-site CA” in such a way that the number of connected radio base stations eNB exceeds the number of radio base stations eNB to which the mobile station UE can simultaneously connect.

(43) In the first feature of the embodiment, the transmission unit 12 may notify the radio base station eNB of the number of CCs usable in the “Inter-site CA”.

(44) Such a configuration can avoid a situation where the radio base station eNB instructs the mobile station UE to perform the “Inter-site CA” in such a way that the number of connected CCs exceeds the number of CCs to which the mobile station UE can simultaneously connect.

(45) In the first feature of the embodiment, the transmission unit 12 may transmit the “UE Capability Information” per unit time.

(46) In such a configuration, the radio base station eNB can distinguish the mobile station UE which can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of subframes and the mobile station UE which can perform the “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state in units of radio frames from each other, and perform controls for the “Inter-site CA” distinctively for each of the mobile stations UE.

(47) In the first feature of the embodiment, the transmission unit 12 may transmit the “UE Capability Information” described above for every frequency band.

(48) In such a configuration, there is no need to transmit multiple pieces of “UE Capability Information” in the same frequency band, and the radio resources can be effectively used.

(49) In the first feature of the embodiment, the transmission unit 12 may transmit the “UE Capability Information” described above for every communication functional block.

(50) In such a configuration, there is no need to transmit multiple pieces of “UE Capability Information” in the same communication functional block, and the radio resources can be effectively used.

(51) In the first feature of the embodiment, the transmission unit 12 may transmit the “UE Capability Information” described above for every “CA band combination (carrier aggregation band combination)”.

(52) In such a configuration, there is no need to transmit multiple pieces of “UE Capability Information” in the same “CA band combination”, and the radio resources can be effectively used.

(53) A second feature of the present embodiment is summarized as a radio base station eNB including: a reception unit 21 configured to receive “UE Capability Information” from a mobile station UE, the “UE Capability Information” indicating whether the mobile station UE is capable of performing “Inter-site CA”; and a control unit 22 configured determine whether to cause the mobile station UE to perform the “Inter-site CA” based on the “UE Capability Information”.

(54) A third feature of the present embodiment is summarized as a radio base station eNB configured to exchange notifications of a unit time applicable to establish synchronization, with another base station eNB.

(55) Furthermore, the radio base station eNB may be configured such that the notification of the time unit is performed similarly for controls other than the “Inter-site CA” (for example, coordinated multi-point (CoMP) transmission and reception).

(56) It should be noted that the foregoing operations of the mobile stations UE and the radio base station eNB may be implemented by hardware, may be implemented by a software module executed by a processor, or may be implemented in combination of the two.

(57) The software module may be provided in a storage medium in any format, such as 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 register, a hard disk, a removable disk, or a CD-ROM.

(58) The storage medium is connected to a processor so that the processor can read and write information from and to the storage medium. Instead, the storage medium may be integrated in a processor. The storage medium and the processor may be provided inside an ASIC. Such an ASIC may be provided in the mobile stations UE and the radio base station eNB. Otherwise, the storage medium and the processor may be provided as discrete components inside the mobile stations UE and the radio base station eNB.

(59) Hereinabove, the present invention has been described in detail by use of the foregoing embodiments. However, it is apparent to those skilled in the art that the present invention should not be limited to the embodiments described in the specification. The present invention can be implemented as an altered or modified embodiment without departing from the spirit and scope of the present invention, which are determined by the description of the scope of claims. Therefore, the description of the specification is intended for illustrative explanation only and does not impose any limited interpretation on the present invention.

(60) Note that the entire content of Japanese Patent Application No. 2012-287437 (filed on Dec. 28, 2012) is incorporated by reference in the present specification.

INDUSTRIAL APPLICABILITY

(61) As described above, the present invention can provide a mobile station and a radio base station which can appropriately perform “Inter-site CA” using CCs under different radio base stations eNB in the asynchronous state.

EXPLANATION OF THE REFERENCE NUMERALS

(62) eNB radio base station UE mobile station 11, 22 control unit 12, 23 transmission unit 13, 21 reception unit