WO2014132515A1 - 端末装置、プログラム及び通信制御方法 - Google Patents
端末装置、プログラム及び通信制御方法 Download PDFInfo
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- WO2014132515A1 WO2014132515A1 PCT/JP2013/082395 JP2013082395W WO2014132515A1 WO 2014132515 A1 WO2014132515 A1 WO 2014132515A1 JP 2013082395 W JP2013082395 W JP 2013082395W WO 2014132515 A1 WO2014132515 A1 WO 2014132515A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04W56/00—Synchronisation arrangements
- H04W56/001—Synchronization between nodes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
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Definitions
- the present disclosure relates to a terminal device, a program, and a communication control method.
- 4G wireless communication systems are standardized in 3GPP (Third Generation Partnership Project).
- technologies such as carrier aggregation, relay, and MU-MIMO (Multi-User Multiple-Input Multiple-Output) are attracting attention.
- Various techniques have been studied in connection with such carrier aggregation.
- Patent Document 1 discloses a technique for suppressing a reduction in throughput by controlling measurement gap allocation for each component carrier (CC) based on the determination result of the urgency level of handover. ing.
- NCT New Carrier Type
- Legacy CC conventional CC
- NCT means a type of a new CC and also means a CC of that type.
- NCT Synchronization New Carrier Type: SNCT
- SNCT Synchronization New Carrier Type
- UNCT Unsynchronized New Carrier Type
- the UE User Equipment
- the UE in the one CC Can be used for the other CC. That is, the UE does not have to separately synchronize with the synchronization signal (for example, CRS (Common Reference Signal)) in the other CC.
- the UE can synchronize in the SNCT by using the synchronization result in the Legacy CC. It becomes possible to take.
- UNCT is not synchronized with any Legacy CC, but can be synchronized with another UNCT, so if a UE synchronizes with one UNCT of two or more UNCTs synchronized with each other, The synchronization result of the UE in the one UNCT can be used for another CC. In other words, the UE does not have to separately synchronize with another synchronization signal in another CC. Also, even if sufficient CRS is not transmitted in one UNCT and the UE cannot individually synchronize by CRS in the one UNCT, the UE uses the synchronization result in the other UNCT. Thus, it may be possible to achieve synchronization in the one UNCT.
- the UE may not be synchronized by CRS in the certain CC.
- the UE cannot use the synchronization result with the certain CC.
- the synchronization state is lost in the certain CC, the synchronization state is also lost in the other CC. That is, the communication quality of radio communication by the UE is impaired.
- a terminal device includes a communication control unit that controls a wireless communication function so as to be synchronized in the first frequency band.
- the first frequency band is synchronized with the third frequency band.
- the communication control unit uses the synchronization signal transmitted in the third frequency band before the wireless communication function is not synchronized in the second frequency band by the synchronization signal.
- the wireless communication function is controlled so as to synchronize in the first frequency band using the synchronization result in the third frequency band.
- the computer is synchronized in the second frequency band by a synchronization signal transmitted in the second frequency band synchronized with the first frequency band
- the second frequency is
- a program is provided for functioning as a communication control unit that controls a wireless communication function so as to synchronize in the first frequency band using a synchronization result in the band.
- the first frequency band is synchronized with the third frequency band.
- the communication control unit uses the synchronization signal transmitted in the third frequency band before the wireless communication function is not synchronized in the second frequency band by the synchronization signal.
- the wireless communication function is controlled so as to synchronize in the first frequency band using the synchronization result in the third frequency band.
- a communication control method wherein synchronization is performed in the second frequency band by a synchronization signal transmitted in a second frequency band that is synchronized with the first frequency band
- a communication control method including controlling a wireless communication function so as to synchronize in the first frequency band using a synchronization result in the second frequency band.
- the first frequency band is synchronized with the third frequency band.
- the third frequency band is transmitted by the synchronization signal transmitted in the third frequency band. And controlling the wireless communication function so as to synchronize in the first frequency band using the synchronization result in the third frequency band.
- a terminal device uses a synchronization result in one frequency band for another frequency band, it is possible to further stabilize the communication quality of wireless communication by the terminal device. .
- FIG. 2 is an explanatory diagram illustrating an example of a schematic configuration of a communication system according to an embodiment of the present disclosure.
- FIG. It is a block diagram which shows an example of a structure of UE which concerns on one Embodiment. It is explanatory drawing for demonstrating an example of the state before switching of a primary anchor point. It is explanatory drawing for demonstrating an example of the state after the switching of a primary anchor point. It is explanatory drawing for demonstrating the example of case 1 whose primary anchor point and secondary anchor point are CC used by the same picocell. It is explanatory drawing for demonstrating the example of the case 2 which is CC used by the same macrocell as a primary anchor point and a secondary anchor point.
- CC component carriers
- carrier aggregation there are cases where CCs that are continuous in the frequency direction are used and CCs that are separated in the frequency direction are used. In the carrier aggregation, it is possible to set the CC to be used for each UE.
- one of a plurality of CCs used by the UE is a special CC.
- the one special CC is called a PCC (Primary Component Carrier).
- the remainder of the plurality of CCs is called SCC (Secondary Component Carrier).
- the PCC may vary from UE to UE. Hereinafter, this point will be described more specifically with reference to FIG.
- FIG. 1 is an explanatory diagram for explaining an example of the PCC of each UE.
- UE 10A and UE 10B and five CCs 1 to 5 are shown.
- the UE 10A uses two CCs, CC1 and CC2.
- UE10A is using CC2 as PCC.
- the UE 10B uses two CCs, CC2 and CC4.
- UE10B is using CC4 as PCC. In this way, each UE may use a different CC as the PCC.
- the PCC is the most important CC among a plurality of CCs, it is desirable that the communication quality is the most stable CC. Note that which CC is used as a PCC actually depends on how it is mounted.
- the CC where the UE first establishes a connection is the PCC for the UE.
- the SCC is added to the PCC. That is, PCC is a main frequency band, and SCC is an auxiliary frequency band.
- the SCC is changed by deleting an existing SCC and adding a new SCC.
- the PCC is changed by a conventional inter-frequency handover procedure. In the carrier aggregation, the UE cannot use only the SCC, and always uses one PCC.
- PCC is sometimes called a primary cell.
- SCC may be called a secondary cell (Secondary Cell).
- a common reference signal (CRS) is transmitted in each CC. And UE synchronizes in each CC by the said CRS.
- CRS common reference signal
- “Synchronize” in which the UE is in the CC) means to adjust the timing and / or frequency in receiving the signal so that the UE can receive the signal correctly in the CC (eg, , Synchronous tracking).
- the common reference signal is also called a cell-specific reference signal.
- the carrier aggregation is based on the premise that each CC can be used by a Legacy UE (that is, a conventional UE) from the viewpoint of ensuring backward compatibility.
- a legacy UE that is, a conventional UE
- the definition of CC that is more efficient although Legacy UE cannot be used is beginning to be considered. That is, a new CC definition called NCT (New Carrier Type) or additional carrier (Additional Carrier) is being studied.
- NCT New Carrier Type
- Additional Carrier Additional Carrier
- the greatest motivation for the NCT is to reduce CC overhead.
- the overhead is a radio resource other than radio resources used for transmitting user data. That is, the overhead is a radio resource used for control. If the overhead increases, the radio resources that can be used for user data transmission decrease, so the increase is not desirable.
- CRS exists in each CC in the downlink.
- FIG. 2 is an explanatory diagram for explaining an example of a CRS transmitted by CC in the downlink.
- some radio resource blocks (RBs) corresponding to a 20 MHz CC are shown.
- Each RB has a width of 12 subcarriers in the frequency direction and a width of 7 OFDM (Orthogonal Frequency Division Multiplexing) symbols in the time direction.
- OFDM Orthogonal Frequency Division Multiplexing
- CRS is transmitted in each RB. That is, the CRS is transmitted in all RBs that exist over the CC bandwidth in the frequency direction and exist for each slot in the time direction. Therefore, CRS is transmitted in each CC and in each subframe.
- CRS One purpose of CRS is to allow the UE to be synchronized.
- the synchronization includes time synchronization (or timing synchronization) that is synchronization in the time direction and frequency synchronization that is synchronization in the frequency direction.
- the UE can synchronize with high accuracy in the frequency direction and the time direction by CRS.
- UE synchronizes continuously by CRS.
- CRS C-RNTI
- the UE demodulates other received signals based on the phase of the CRS.
- CRS Common Reference Signal
- RS Reference Signal
- CSI-RS Channel State Information-Reference Signal
- the purpose of current CRS is mainly to allow the UE to be synchronized. Therefore, as long as UE can synchronize, it is also possible to reduce the frequency with which CRS is transmitted.
- NCT Synchronized NCT
- NCT Unchronized NCT
- a CRS is transmitted at UNCT.
- NCT includes SNCT and UNCT.
- SNCT As described above, NCT includes SNCT and UNCT.
- specific examples of SNCT and UNCT will be described with reference to FIG.
- FIG. 3 is an explanatory diagram for explaining an example of NCT.
- five CCs 40 are shown.
- CC 40A and CC 40B are Legacy CCs.
- CC 40A and CC 40B are synchronized with each other.
- CC40C, CC40D, and CC40E are NCT. More specifically, it is an SNCT in which CC40C is synchronized with both CC40A and CC40B, which are Legacy CCs.
- CC 40D and CC 40E are UNCTs that are not synchronized with either CC 40A or CC 40B. In this example, CC 40D and CC 40E are not synchronized with each other.
- the RB to which CRS is transmitted is reduced to 6 RB, 25 RB, or 50 RB.
- this point will be specifically described with reference to FIG.
- FIG. 4 is an explanatory diagram for explaining an example of CRS reduction in the frequency direction.
- a case where the RB for transmitting the CRS is set to 6 RBs in the frequency direction and a case where the RB for transmitting the CRS is set to 25 RBs in the frequency direction are shown. In this way, the CRS is not transmitted in all RBs existing in the frequency direction, but is transmitted in a limited RB.
- the CRS transmission cycle is set to 5 ms or 10 ms. This point will be specifically described with reference to FIG.
- FIG. 5 is an explanatory diagram for explaining an example of CRS reduction in the time direction. Referring to FIG. 5, a case where the CRS transmission period is 5 ms and a case where the CRS transmission period is 10 ms are shown. In this way, the CRS is not transmitted in all slots or all subframes in the time direction, but is transmitted in a limited subframe.
- Synchronized NCT is synchronized with Legacy CC, so it is basically possible to delete conventional CRS in SNCT.
- the UE monitors whether or not the UE is synchronized based on a block error rate (BLER) of PDCCH (Physical Downlink Control CHannel). In other words, the UE detects the UE out of synchronization based on the PDCCH BLER. For example, when the BLER of PDCCH becomes 10% or more, the UE detects loss of synchronization.
- BLER block error rate
- the timer starts. Then, when the timer expires (expire), RLF (Radio Link Failure) is recognized.
- RLF Radio Link Failure
- the UE performs the synchronization monitoring as described above on the PCC, but does not perform it on the SCC.
- the UE deactivates the SCC when PDCCH is not detected in the SCC.
- Release 12 NCT is a study item (SI) approved in September 2012 as RP-12415 at 3GPP RAN # 57 Plenary meeting. This SI is divided into phase 1 and phase 2. In Phase 1, a study on enhancement of Release 11 NCT is performed, and in Phase 2, a study considering a small cell scenario is planned. Specifically, the small cell is, for example, a pico cell, a nano cell, a femto cell, or the like. In this specification, a pico cell will be described as a specific example of a small cell.
- FIG. 6 is an explanatory diagram for explaining examples of three arrangement scenarios of small cells.
- a macro cell 21 and three pico cells 31A, 31B and 31C are shown.
- a macro eNodeB 20 that is a base station of the macro cell 21 and a pico eNodeB 30 that is a base station of these pico cells 311 are also shown.
- the pico cell 31A entirely overlaps the macro cell 21, the pico cell 31B partially overlaps the macro cell 21, and the pico cell 31C does not overlap the macro cell 21.
- the arrangement of the pico cell 31A corresponds to the first arrangement scenario
- the arrangement of the pico cell 31B corresponds to the second arrangement scenario
- the arrangement of the pico cell 31C corresponds to the third arrangement scenario.
- the macro cell 21 performs wireless communication using the frequency band F1.
- wireless communication is performed using the frequency band F2.
- the eNodeB uses, for example, system information (System Information) or RRC (Radio Resource Control) signaling.
- system information System Information
- RRC Radio Resource Control
- FIG. 7 is an explanatory diagram for explaining the features of system information and RRC signaling. Referring to FIG. 7, for system information and RRC signaling, the state of the UE necessary for the eNodeB to provide control information to the UE, the UE to be provided (and information to be provided), and the amount of information that can be provided are shown. Has been.
- the UE may be either RRC_Connected (ie, connected state) or RRC_Idle (ie, idle state).
- RRC_Connected ie, connected state
- RRC_Idle ie, idle state
- the UE in order for the eNodeB to provide control information through RRC signaling, the UE must be RRC_Connected (ie, connected state).
- control information is provided to all UEs, not individual UEs. That is, it can be said that the control information provided by the system information is information common to the UE.
- control information is basically provided to individual UEs. That is, it can be said that the control information provided by RRC signaling is basically control information of an individual UE.
- RRC signaling it is also possible to provide common information to UEs by RRC signaling by transmitting common control information by RRC signaling to different UEs.
- the system information includes limited control information and is transmitted using limited radio resources. For this reason, the amount of control information provided as system information is small.
- RRC signaling is transmitted relatively freely by PDSCH (Physical Downlink Shared CHannel). Therefore, the amount of control information provided by RRC signaling is large.
- FIG. 8 is an explanatory diagram for explaining time synchronization between component carriers.
- the reception timings of CC1 and CC2 are shown.
- CC1 and CC2 can be regarded as being synchronized with each other in the time direction.
- FIG. 9 is an explanatory diagram for explaining frequency synchronization between component carriers.
- the frequency band of CC1 and the frequency band of CC2 are shown.
- the center frequency of CC1 and the center frequency of CC2 are also shown.
- the center frequency of CC1 and the center frequency of CC2 are separated by a predetermined frequency width.
- a shift in the frequency direction may occur between a frequency that is a predetermined frequency width away from the center frequency of CC1 and the center frequency of CC2.
- a predetermined frequency width for example, 500 Hz in LTE (Long Term Evolution)
- synchronization between frequency bands includes time synchronization and frequency synchronization. Therefore, the following four cases exist for synchronization between frequency bands.
- Case 1 There is both time synchronization and frequency synchronization
- Case 2 There is time synchronization, but there is no frequency synchronization
- Case 3 There is no time synchronization, but there is frequency synchronization
- Case 4 There is no both time synchronization and frequency domain
- the frequency bands synchronized with each other are frequency bands corresponding to Case 1.
- the frequency bands corresponding to case 2 or case 3 may also be regarded as frequency bands synchronized with each other (in the time direction or the frequency direction).
- synchronization between frequency bands includes synchronization on the eNodeB side (that is, the network side) and synchronization on the UE. And even if there is time synchronization and frequency synchronization on the eNodeB side for two CCs, it is unclear whether the UE side has time synchronization and frequency synchronization when receiving signals on the two CCs.
- the propagation path of CC1 and the propagation path of CC2 are different, and as a result, the arrival times of signals may be different. In this case, time synchronization is lost.
- the CC1 radio wave and the CC2 radio wave may arrive at the UE from different directions.
- the frequency of CC1 transitions from frequency f to frequency f + ⁇ f due to the Doppler effect.
- the frequency band of CC2 transitions from the frequency f to the frequency f ⁇ f due to the Doppler effect.
- frequency synchronization is lost due to the Doppler effect.
- NCT is considered as a new component carrier separately from Legacy CC (conventional CC) that can maintain backward compatibility.
- NCT means a type of a new CC and also means a CC of that type.
- NCT that is synchronized with Legacy CC (that is, SNCT) and NCT that is not synchronized with Legacy CC (that is, UNCT) are being studied.
- the SNCT Since the SNCT is synchronized with one of the legacy CCs, if the UE synchronizes with one CC among the SNCT and the legacy CC that are synchronized with each other, the synchronization result of the UE with respect to the other CC is obtained. It can be used for CC. That is, the UE does not have to separately synchronize with the synchronization signal in the other CC. Further, even when sufficient CRS is not transmitted in the SNCT and the UE cannot be synchronized individually by the CRS in the SNCT, the UE can synchronize in the SNCT by using the synchronization result in the Legacy CC. It becomes possible to take.
- UNCT is not synchronized with any Legacy CC, but can be synchronized with another UNCT
- the UE synchronizes with one CC of two or more UNCTs synchronized with each other
- the synchronization result of the UE in the one CC can be used for another CC. That is, the UE does not have to separately synchronize with the synchronization signal in the other CC.
- the UE uses the synchronization result in the other UNCT.
- FIG. 10 is an explanatory diagram illustrating an example of a schematic configuration of the communication system 1 according to the embodiment of the present disclosure.
- the communication system 1 includes a UE 100, a macro eNodeB 200, and a pico eNodeB 300.
- the communication system 1 is a system compliant with LTE-Advanced.
- the UE 100 performs radio communication with the macro eNodeB 200 within the maxell 21. Further, the UE 100 performs radio communication with the pico eNodeB 300 in the pico cell 31.
- the UE 100 can simultaneously use a plurality of CCs for radio communication. Specifically, for example, the UE 100 can perform radio communication with the macro eNodeB 200 and / or the pico eNodeB 300 using a plurality of CCs simultaneously. That is, the UE 100 supports carrier aggregation.
- the macro eNodeB 200 performs radio communication with the UE 100 located in the macro cell 21.
- the macro eNodeB 200 performs wireless communication using one or more component carriers (CC).
- CC component carriers
- each of the one or more CCs used by the macro eNodeB 200 is a CC different from any of the one or more CCs used in the pico cell 31.
- the macro eNodeB 200 transmits a synchronization signal for the UE 100 to synchronize with the one or more CCs.
- the synchronization signal is CRS.
- the macro eNodeB 200 performs wireless communication using a plurality of CCs. And macro eNodeB200 can use several CC simultaneously for radio
- the pico eNodeB 300 performs radio communication with the UE 100 located in the pico cell 31 that partially or entirely overlaps the macro cell 21.
- the pico eNodeB 300 performs wireless communication using one or more CCs.
- each of the one or more CCs used by the pico eNodeB 300 is a CC different from any of the one or more CCs used in the macro cell cell 21.
- the pico eNodeB 300 transmits a synchronization signal for the UE 100 to synchronize with the one or more CCs.
- the synchronization signal is CRS.
- the pico eNodeB 300 performs wireless communication using a plurality of CCs. And pico eNodeB300 can use several CC simultaneously for radio
- the pico cell 31 is arranged as in the first arrangement scenario (that is, Deployment Scenario 1) or the second arrangement scenario (that is, Deployment Scenario 2).
- FIG. 11 is a block diagram illustrating an example of the configuration of the UE 100 according to the present embodiment.
- the UE 100 includes an antenna unit 110, a radio communication unit 120, a storage unit 130, and a control unit 140.
- the antenna unit 110 receives a radio signal and outputs the received radio signal to the radio communication unit 120.
- the antenna unit 110 transmits the transmission signal output from the wireless communication unit 120.
- the radio communication unit 120 performs radio communication with the macro eNodeB 200 when the UE 100 is located in the macro cell 21. In addition, the radio communication unit 120 performs radio communication with the pico eNodeB 300 when the UE 100 is located in the pico cell 31.
- the wireless communication unit 120 can simultaneously use a plurality of CCs for wireless communication. Specifically, for example, the wireless communication unit 120 can perform wireless communication with the macro eNodeB 200 and / or the pico eNodeB 300 using a plurality of CCs simultaneously. That is, the UE 100 supports carrier aggregation.
- the wireless communication unit 120 synchronizes in the CC by a synchronization signal transmitted in the CC.
- the synchronization signal is CRS.
- the storage unit 130 stores a program and data for the operation of the UE 100.
- Control unit 140 The control unit 140 provides various functions of the UE 100.
- the control unit 140 includes a communication control unit 141.
- the communication control unit 141 controls wireless communication by the UE 100.
- the communication control unit 141 includes a second CC (hereinafter referred to as "CC2”) synchronized with a first component carrier (CC) (hereinafter referred to as "CC1").
- CC2 second CC
- CC1 first component carrier
- the wireless communication function is controlled so that synchronization is performed in CC2 by the synchronization signal transmitted in (1), and synchronization is performed in CC1 using the synchronization result in CC2.
- the synchronization signal is CRS.
- the wireless communication function is the wireless communication unit 120. That is, the communication control unit 141 controls the wireless communication unit 120 so that synchronization is performed in CC2 by CRS transmitted in CC2, and synchronization is performed in CC1 using a synchronization result in CC2.
- CC1 is also synchronized with a third CC (hereinafter referred to as "CC3"). Then, the communication control unit 141 synchronizes in CC3 with the synchronization signal transmitted in CC3 before the wireless communication function is not synchronized in CC2 with the synchronization signal, and uses the synchronization result in CC3. The wireless communication function is controlled so as to synchronize with CC1.
- the communication control unit 141 synchronizes in CC3 by CRS transmitted in CC3 before the wireless communication unit 120 becomes out of synchronization in CC2 by CRS, and synchronizes in CC1 using the synchronization result in CC3.
- the wireless communication unit 120 is controlled. That is, the CC on the synchronization result providing side is switched from CC2 to CC3.
- the CCs on the providing side of the synchronization result at that time are called “primary anchor points”.
- a CC that is a candidate for the next primary anchor point, such as CC3 before switching, is referred to as a “secondary anchor point”.
- the CC on the synchronization result providing side and its candidates are also simply referred to as “anchor points”.
- a CC on the use side of the synchronization result, such as CC1 is referred to as a “slave”.
- FIG. 12A is an explanatory diagram for explaining an example of a state before switching of the primary anchor point.
- CC2 and CC3 synchronized with CC1 are shown.
- the UE 100 synchronizes with the CRS by the CRS, and synchronizes with the CC 1 using the synchronization result of the CC 2. That is, in this example, CC1 is a slave and CC2 is a primary anchor point.
- CC3 is a candidate for the next primary anchor point. That is, CC3 is a secondary anchor point.
- the UE 100 becomes unable to synchronize with the CRS at the primary anchor point CC2, but before that, the UE 100 switches the primary anchor point from CC2 to CC3.
- FIG. 12B is an explanatory diagram for explaining an example of a state after switching the primary anchor point.
- CC2 and CC3 synchronized with CC1 are shown, similar to FIG. 12A.
- the UE 100 switches the primary anchor point from CC2 to CC3. That is, CC3 is a new primary anchor point. Therefore, UE100 synchronizes by CRS in CC3, and synchronizes in CC1 using the synchronization result in CC3.
- CC2 which was the primary anchor point, becomes a secondary anchor point after switching, for example.
- the CC on the synchronization result providing side is switched. That is, the primary anchor point is switched. Thereby, it becomes possible to stabilize the communication quality of the radio
- the UE 100 since the primary anchor point is switched from CC2 to CC3 before the UE 100 becomes unsynchronized at CC2, the UE 100 is synchronized by CRS at CC3 even after it becomes unsynchronized by CRS at CC2. It becomes possible to continue taking. Therefore, the UE 100 can continue to synchronize with the slave (CC1) using the synchronization result at the primary anchor point. As a result, the communication quality of radio communication by the UE 100 in the slave (CC1) is further stabilized.
- communication control unit 141 synchronizes in CC3 and synchronizes in CC1 using the synchronization result in CC3. To control the wireless communication function.
- the communication control unit 141 switches the primary anchor point from CC2 to CC3 when the accuracy of synchronization in CC2 satisfies the predetermined switching condition.
- the wireless communication unit 120 synchronizes with CC3 by CRS, and synchronizes with CC1 using the synchronization result in CC3.
- the predetermined switching condition includes that the accuracy of synchronization in CC2 is lower than the accuracy of synchronization in CC3.
- the communication control unit 141 switches the primary anchor point from CC2 to CC3 when the synchronization accuracy in CC2 is lower than the synchronization accuracy in CC3.
- the communication control unit 141 synchronizes with both the primary anchor point CC2 and the secondary anchor point CC3 by CRS, and monitors the accuracy of synchronization in each of CC2 and CC3. .
- the communication control unit 141 monitors the accuracy of synchronization using the PDCCH BLER. That is, the communication control unit 141 considers that the synchronization accuracy is high when the PDCCH BLER is low, and regards the synchronization accuracy as low when the PDCCH BLER is high.
- the communication control unit 141 sets the primary anchor point to CC2 when the accuracy of synchronization in CC2 is lower than the accuracy of synchronization in CC3, that is, when the BLER of PDCCH in CC2 is higher than the BLER of PDCCH in CC3. To CC3.
- the UE 100 can synchronize with higher accuracy in the slave (CC1). As a result, the communication quality of radio communication by the UE 100 in the slave (CC1) is further stabilized.
- the predetermined switching condition may include that the accuracy of synchronization in CC2 is lower than a predetermined accuracy.
- the communication control unit 141 may switch the primary anchor point from CC2 to CC3 when the synchronization accuracy in CC2 is lower than a predetermined accuracy.
- the communication control unit 141 synchronizes with CRS in CC2 that is the primary anchor point, and monitors the accuracy of synchronization in CC2. As described above, as an example, the communication control unit 141 monitors the accuracy of synchronization using the PDCCH BLER. Then, when the accuracy of synchronization in CC2 is lower than a predetermined accuracy, that is, when the BLER of PDCCH in CC2 is higher than a predetermined BLER (for example, 1%), the communication control unit 141 Is switched from CC2 to CC3.
- a predetermined accuracy that is, when the BLER of PDCCH in CC2 is higher than a predetermined BLER (for example, 1%
- the UE 100 can synchronize with a certain degree of accuracy in the slave (CC1). As a result, the communication quality of radio communication by the UE 100 in the slave (CC1) is further stabilized. Moreover, since the object of acquisition and monitoring of synchronization is limited to the primary anchor point, the load on the UE 100 can be further suppressed.
- CC1 is a CC in which a synchronization signal is not transmitted in at least one of the subframes that are units of time in wireless communication.
- CC1 is a CC in which CRS is not transmitted in any subframe. That is, CC1 is NCT.
- the synchronization signal transmitted by CC1 is less than the synchronization signal transmitted by CC2 and CC3.
- the CRS transmitted in CC1 is less than the CRS transmitted in each of CC2 and CC3.
- the UE 100 synchronizes at CC1 using the synchronization result by CRS at the primary anchor point (CC2 or CC3) instead of individually synchronizing by CRS at CC1, thereby enabling more at CC1. Synchronize with high accuracy. As a result, the communication quality of radio communication by the UE 100 in CC1 becomes more stable.
- the synchronization signal transmitted in CC1 is less than the synchronization signal required for synchronization in CC1.
- CRS transmitted in CC1 is less than CRS required for synchronization in CC1.
- the UE 100 cannot individually synchronize with the CRS in the CC1, but can synchronize with the CC1 by using the synchronization result by the CRS at the primary anchor point (CC2 or CC3).
- CC1 as a slave is a CC used in the picocell 31.
- the pico cell 31 is a narrow area, it may be difficult to synchronize by CRS in the CC used in the pico cell 31 due to the movement of the UE 100. That is, when the UE 100 moves, the communication quality of radio communication in the CC used in the pico cell 31 is less stable.
- the synchronization result at the anchor point is used for the CC (that is, the slave) of the pico cell 31, so that the synchronization accuracy in the CC used in the pico cell 31 can be improved. As a result, the communication quality of radio communication by the UE 100 in CC1 can be more stable.
- the synchronization result in another CC is used for the CC used in the pico cell 31, it is possible to transmit no CRS in the pico cell 31 or reduce the amount of CRS transmitted in the pico cell 31. As a result, the throughput in the pico cell 31 can be improved.
- Case 1 CC used in the same cell (pico cell)
- Case 2 CC used in the same cell (macro cell)
- Case 3 CC used in one of neighboring cells (picocell) and CC used in the other
- Case 4 CC used in one of adjacent cells (macrocell) and CC used in the other
- Case 5 CC used in a macro cell and CC used in a pico cell
- CC used in the same cell (cases 1 and 2)
- CC2 and CC3 are CCs used in the same cell.
- CC2 and CC3 are CCs used in the same picocell 31. This corresponds to Case 1 above.
- CC2 and CC3 are CCs used in the same picocell 31. This corresponds to Case 1 above.
- a specific example of this point will be described with reference to FIG.
- FIG. 13 is an explanatory diagram for explaining an example of Case 1 in which the primary anchor point and the secondary anchor point are CCs used in the same pico cell 31.
- UE 100, macro eNodeB 200 of macro cell 21, and pico eNodeB 300 of pico cell 31 are illustrated, as in FIG. 10.
- CC1 as a slave, CC2 as a primary anchor point, and CC3 as a secondary anchor point are shown.
- both CC2 and CC3 are CCs used in picocell 31A.
- CC1 is also a CC used in the picocell 31A.
- the UE 100 switches the primary anchor point from the CC2 of the picocell 31A to the CC3 of the picocell 31A before being synchronized by CRS in the CC2 of the picocell 31A.
- CC2 and CC3 are CCs used in the same macro cell 21. This corresponds to Case 2 above.
- a specific example of this point will be described with reference to FIG.
- FIG. 14 is an explanatory diagram for explaining an example of Case 2 in which the primary anchor point and the secondary anchor point are CCs used in the same macro cell 21.
- both CC2 and CC3 are CCs used in the macro cell 21.
- CC1 is a CC used in the picocell 31A. Then, the UE 100 switches the primary anchor point from the CC2 of the macrocell 21 to the CC3 of the macrocell 21 before being synchronized by CRS in CC2 of the macrocell 21.
- CC2 and CC3 can be CCs used in the same cell.
- the UE 100 may be able to synchronize by CRS in CC3 that is the secondary anchor point even in a region where it is difficult to synchronize by CRS in CC2 that is the primary anchor point. Therefore, the UE 100 can further stabilize the communication quality of radio communication performed by the UE 100 by using CCs used in the same cell as the primary anchor point and the secondary anchor point.
- CCs used in different cells are not synchronized with each other, even when the UE 100 cannot receive signals of different cells, the UE 100 uses the CCs synchronized with each other as anchor points in the UE 100. , Communication quality in CC1 can be further stabilized.
- CC2 and CC3 are CCs used in different cells.
- CC2 is a CC used in the first cell
- CC3 is a CC used in a second cell adjacent to the first cell.
- CC2 is a CC used in the first picocell 31
- CC3 is a CC used in the second picocell 31 adjacent to the first picocell 31. This corresponds to Case 3 above.
- a specific example of this point will be described with reference to FIG.
- FIG. 15 is an explanatory diagram for explaining an example of Case 3 in which the primary anchor point is a CC used in the first pico cell 31 and the secondary anchor point is a CC used in the second pico cell 31.
- CC2 is a CC used in picocell 31A
- CC3 is a CC used in picocell 31B
- CC1 is a CC used in the picocell 31A.
- the UE 100 switches the primary anchor point from the CC2 of the picocell 31A to the CC3 of the picocell 31B before being synchronized by CRS in the CC2 of the picocell 31A.
- CC 2 is a CC used in the first macro cell 21
- CC 3 is a CC used in the second macro cell 21 adjacent to the first macro cell 21.
- FIG. 16 is an explanatory diagram for explaining an example of Case 4 in which the primary anchor point is a CC used in the first macro cell 21 and the secondary anchor point is a CC used in the second macro cell 21.
- UE 100, macro eNodeB 200A of macro cell 21A, and macro eNodeB 200B of macro cell 21B are shown.
- CC2 is a CC used in the macro cell 21A
- CC3 is a CC used in the macro cell 21B.
- CC1 is CC used by picocell 31 (not shown).
- the UE 100 switches the primary anchor point from the CC2 of the macrocell 21A to the CC3 of the macrocell 21B before being synchronized by CRS in the CC2 of the macrocell 21A.
- CC2 may be a CC used in a certain cell
- CC3 may be a CC used in another cell.
- CRS CRS
- CC used in macro cell and CC used in pico cell are CCs used in different cells.
- CC2 is one of the CC used in the picocell 31 and the CC used in the macrocell 21.
- CC3 is the other CC among the CC used in the picocell 31 and the CC used in the macrocell 21. This corresponds to Case 5 above.
- CC2 is a CC used in the picocell 31 and CC3 is a CC used in the macrocell 21.
- CC3 is a CC used in the macrocell 21.
- FIG. 17 is an explanatory diagram for explaining a first example of case 5 in which the primary anchor point is a CC used in the pico cell 31 and the secondary anchor point is a CC used in the macro cell 21.
- CC2 is a CC used in picocell 31A
- CC3 is a CC used in macrocell 21.
- CC1 is a CC used in the picocell 31A.
- the UE 100 can synchronize with a new primary anchor point with high probability. Therefore, the communication quality of the radio communication by UE100 in CC1 can be stabilized more.
- CC 2 is a CC used in the macro cell 21
- CC 3 is a CC used in the pico cell 31.
- FIG. 18 is an explanatory diagram for explaining a first example of case 5 in which the primary anchor point is a CC used in the macro cell 21 and the secondary anchor point is a CC used in the pico cell 31.
- CC2 is a CC used in the macro cell 21
- CC3 is a CC used in the pico cell 31A.
- CC1 is a CC used in the picocell 31A.
- the pico cell (eg, located near the cell edge) 31 CCs are primary anchor points. Therefore, the UE 100 can synchronize at the new primary anchor point. Therefore, the communication quality of the radio communication by UE100 in CC1 can be stabilized more.
- the communication control unit 141 searches for another CC that is synchronized with CC1 other than CC2 and CC3. That is, the communication control unit 141 searches for a new anchor point candidate.
- the predetermined search condition is that the synchronization accuracy at the secondary anchor point is lower than the predetermined accuracy. That is, the communication control unit 141 searches for another CC that is synchronized with the slave (CC1) when the synchronization accuracy at the secondary anchor point (CC3) is lower than a predetermined accuracy.
- the communication control unit 141 performs synchronization by CRS in CC3 that is the secondary anchor point, and monitors the accuracy of synchronization in CC3. As described above, as an example, the communication control unit 141 monitors the accuracy of synchronization using the PDCCH BLER. Then, the communication control unit 141 synchronizes with CC1 when the accuracy of synchronization in CC3 is lower than a predetermined accuracy, that is, when the BLER of PDCCH in CC3 is higher than a predetermined BLER (for example, 1%). Search for another CC to perform.
- a predetermined accuracy that is, when the BLER of PDCCH in CC3 is higher than a predetermined BLER (for example, 1%).
- the predetermined search condition may be that the primary anchor point is switched. That is, when switching the primary anchor point from CC2 to CC3, the communication control unit 141 may search for another CC that is synchronized with the slave (CC1).
- the communication control unit 141 uses the synchronization signal transmitted by the CC2 to transmit the wireless communication function. Instead of synchronizing at CC3 before synchronizing at CC2, synchronize at CC4 with a synchronization signal transmitted at CC4 and use the synchronization result at CC4 to synchronize at CC1. Control communication functions. That is, the communication control unit 141 switches the secondary anchor point to CC4 when CC4 is searched.
- the communication control unit 141 stops using CC1 when a predetermined end condition is satisfied.
- the predetermined termination condition includes that the accuracy of synchronization in any CC synchronized with CC1 is lower than the predetermined accuracy.
- the communication control unit 141 stops using the slave (CC1) when the accuracy of synchronization in any CC synchronized with the slave (CC1) is lower than a predetermined accuracy.
- the communication control unit 141 performs synchronization by CRS individually in the slave.
- the wireless communication unit 120 may be controlled.
- the communication control unit 141 does not cause the UE 100 to be in a connection state for radio resources in at least one of CC2 and CC3.
- the communication control unit 141 does not cause the UE 100 to be in a connection state for radio resources in at least one of CC2 and CC3.
- FIG. 19 is an explanatory diagram for explaining an example in a case where the UE 100 does not enter a connected state in the CC.
- CC2 and CC3 that are synchronized with CC1 are shown, as in FIG. 12A.
- CC1 is a slave
- CC2 is a primary anchor point
- CC3 is a secondary anchor point.
- the communication control unit 141 does not cause the UE 100 to be RRC_Connected in CC2.
- the UE 100 simply synchronizes with CRS by CRS and uses the synchronization result in CC2.
- the resource consumption in the eNodeB using at least one CC is suppressed. More specifically, if the CC becomes RRC_Connected, resources in the eNodeB that uses the CC may be consumed. For example, in the eNodeB, memory resources for holding data addressed to the UE 100, radio resources for signaling to the UE 100, processing resources for signaling to the UE 100, and the like can be consumed. Therefore, as described above, if the UE 100 does not become RRC_Connected, consumption of the resources can be suppressed.
- CC1 may be a CC used in the picocell 31, and the at least one CC may be a CC used in the macrocell 21.
- the UE 100 since a large number of UEs 100 may exist in the macro cell 21, a particularly large amount of resources may be consumed. Therefore, the UE 100 does not become RRC_Connected in the at least one CC (the CC of the macro cell 21), so that resource consumption can be significantly suppressed.
- FIG. 20 is a flowchart illustrating an example of a schematic flow of a communication control process according to the present embodiment.
- step S401 the communication control unit 141 determines a primary anchor point, a secondary anchor point, and a slave.
- step S403 the communication control unit 141 synchronizes with the CRS at the primary anchor point, and synchronizes with the slave using the synchronization result at the primary anchor point.
- step S405 the communication control unit 141 determines whether the accuracy of synchronization at the primary anchor point satisfies a predetermined switching condition. If the predetermined switching condition is satisfied, the process proceeds to step S407. Otherwise, the process proceeds to step S409.
- step S407 the communication control unit 141 switches the primary anchor point. That is, the communication control unit 141 sets the CC that is the secondary anchor point at that time as a new primary anchor point. For example, the communication control unit 141 sets the CC that was the primary anchor point until just before as a new secondary anchor point.
- step S409 the communication control unit 141 determines whether a predetermined search condition is satisfied. If the predetermined search condition is satisfied, the process proceeds to step S411. Otherwise, the process returns to step S403.
- step S411 the communication control unit 141 searches for another CC synchronized with the slave other than the primary anchor point and the secondary anchor point at that time.
- step S413 the communication control unit 141 determines whether another CC that is synchronized with the slave is searched. If another CC is found, the process proceeds to step S415. Otherwise, the process proceeds to step S417.
- step S415 the communication control unit 141 switches the secondary anchor point to the searched CC.
- step S417 the communication control unit 141 determines whether a predetermined end condition is satisfied.
- the predetermined termination condition includes that the accuracy of synchronization in any CC synchronized with the slave is lower than the predetermined accuracy. If the predetermined end condition is satisfied, the process proceeds to step S419. Otherwise, the process returns to step S403.
- step S419 the communication control unit 141 stops using the slave. Then, the process ends.
- the UE 100 is realized as a mobile terminal such as a smartphone, a tablet PC (Personal Computer), a notebook PC, a portable game terminal, a portable / dongle type mobile router or a digital camera, or an in-vehicle terminal such as a car navigation device. Also good. Further, the UE 100 may be realized as a terminal (also referred to as an MTC (Machine Type Communication) terminal) that performs M2M (Machine To Machine) communication. Further, the UE 100 may be a wireless communication module (for example, an integrated circuit module configured by one die) mounted on these terminals.
- MTC Machine Type Communication
- M2M Machine To Machine
- FIG. 21 is a block diagram illustrating an example of a schematic configuration of a smartphone 900 to which the technology according to the present disclosure can be applied.
- the smartphone 900 includes a processor 901, a memory 902, a storage 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, a display device 910, a speaker 911, a wireless communication interface 912, one or more antenna switches 915.
- One or more antennas 916, a bus 917, a battery 918 and an auxiliary controller 919 are provided.
- the processor 901 may be, for example, a CPU or a SoC (System on Chip), and controls the functions of the application layer and other layers of the smartphone 900.
- the memory 902 includes a RAM and a ROM, and stores programs executed by the processor 901 and data.
- the storage 903 can include a storage medium such as a semiconductor memory or a hard disk.
- the external connection interface 904 is an interface for connecting an external device such as a memory card or a USB (Universal Serial Bus) device to the smartphone 900.
- the camera 906 includes, for example, an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and generates a captured image.
- the sensor 907 may include a sensor group such as a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor.
- the microphone 908 converts sound input to the smartphone 900 into an audio signal.
- the input device 909 includes, for example, a touch sensor that detects a touch on the screen of the display device 910, a keypad, a keyboard, a button, or a switch, and receives an operation or information input from a user.
- the display device 910 has a screen such as a liquid crystal display (LCD) or an organic light emitting diode (OLED) display, and displays an output image of the smartphone 900.
- the speaker 911 converts an audio signal output from the smartphone 900 into audio.
- the wireless communication interface 912 supports any cellular communication method such as LTE or LTE-Advanced, and performs wireless communication.
- the wireless communication interface 912 may typically include a BB processor 913, an RF circuit 914, and the like.
- the BB processor 913 may perform, for example, encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and performs various signal processing for wireless communication.
- the RF circuit 914 may include a mixer, a filter, an amplifier, and the like, and transmits and receives radio signals via the antenna 916.
- the wireless communication interface 912 may be a one-chip module in which the BB processor 913 and the RF circuit 914 are integrated.
- the wireless communication interface 912 may include a plurality of BB processors 913 and a plurality of RF circuits 914 as illustrated in FIG. 21 illustrates an example in which the wireless communication interface 912 includes a plurality of BB processors 913 and a plurality of RF circuits 914, the wireless communication interface 912 includes a single BB processor 913 or a single RF circuit 914. But you can.
- the wireless communication interface 912 may support other types of wireless communication methods such as a short-range wireless communication method, a proximity wireless communication method, or a wireless LAN (Local Area Network) method in addition to the cellular communication method.
- a BB processor 913 and an RF circuit 914 for each wireless communication method may be included.
- Each of the antenna switches 915 switches the connection destination of the antenna 916 among a plurality of circuits (for example, circuits for different wireless communication systems) included in the wireless communication interface 912.
- Each of the antennas 916 includes a single or a plurality of antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna), and is used for transmission / reception of a radio signal by the radio communication interface 912.
- the smartphone 900 may include a plurality of antennas 916 as illustrated in FIG. 21 illustrates an example in which the smartphone 900 includes a plurality of antennas 916, the smartphone 900 may include a single antenna 916.
- the smartphone 900 may include an antenna 916 for each wireless communication method.
- the antenna switch 915 may be omitted from the configuration of the smartphone 900.
- the bus 917 connects the processor 901, the memory 902, the storage 903, the external connection interface 904, the camera 906, the sensor 907, the microphone 908, the input device 909, the display device 910, the speaker 911, the wireless communication interface 912, and the auxiliary controller 919 to each other.
- the battery 918 supplies electric power to each block of the smartphone 900 shown in FIG. 21 through a power supply line partially shown by a broken line in the drawing.
- the auxiliary controller 919 operates the minimum necessary functions of the smartphone 900 in the sleep mode.
- the communication control unit 141 described with reference to FIG. 11 may be implemented in the wireless communication interface 912. Further, at least a part of this function may be implemented in the processor 901 or the auxiliary controller 919.
- FIG. 22 is a block diagram illustrating an example of a schematic configuration of a car navigation device 920 to which the technology according to the present disclosure can be applied.
- the car navigation apparatus 920 includes a processor 921, a memory 922, a GPS (Global Positioning System) module 924, a sensor 925, a data interface 926, a content player 927, a storage medium interface 928, an input device 929, a display device 930, a speaker 931, and wireless communication.
- the interface 933 includes one or more antenna switches 936, one or more antennas 937, and a battery 938.
- the processor 921 may be a CPU or SoC, for example, and controls the navigation function and other functions of the car navigation device 920.
- the memory 922 includes RAM and ROM, and stores programs and data executed by the processor 921.
- the GPS module 924 measures the position (for example, latitude, longitude, and altitude) of the car navigation device 920 using GPS signals received from GPS satellites.
- the sensor 925 may include a sensor group such as a gyro sensor, a geomagnetic sensor, and an atmospheric pressure sensor.
- the data interface 926 is connected to the in-vehicle network 941 through a terminal (not shown), for example, and acquires data generated on the vehicle side such as vehicle speed data.
- the content player 927 reproduces content stored in a storage medium (for example, CD or DVD) inserted into the storage medium interface 928.
- the input device 929 includes, for example, a touch sensor, a button, or a switch that detects a touch on the screen of the display device 930, and receives an operation or information input from the user.
- the display device 930 has a screen such as an LCD or an OLED display, and displays a navigation function or an image of content to be reproduced.
- the speaker 931 outputs the navigation function or the audio of the content to be played back.
- the wireless communication interface 933 supports any cellular communication method such as LTE or LTE-Advanced, and performs wireless communication.
- the wireless communication interface 933 may typically include a BB processor 934, an RF circuit 935, and the like.
- the BB processor 934 may perform, for example, encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and performs various signal processing for wireless communication.
- the RF circuit 935 may include a mixer, a filter, an amplifier, and the like, and transmits and receives a radio signal via the antenna 937.
- the wireless communication interface 933 may be a one-chip module in which the BB processor 934 and the RF circuit 935 are integrated.
- the wireless communication interface 933 may include a plurality of BB processors 934 and a plurality of RF circuits 935 as shown in FIG. 22 illustrates an example in which the wireless communication interface 933 includes a plurality of BB processors 934 and a plurality of RF circuits 935, the wireless communication interface 933 includes a single BB processor 934 or a single RF circuit 935. But you can.
- the wireless communication interface 933 may support other types of wireless communication methods such as a short-range wireless communication method, a proximity wireless communication method, or a wireless LAN method in addition to the cellular communication method.
- a BB processor 934 and an RF circuit 935 may be included for each communication method.
- Each of the antenna switches 936 switches the connection destination of the antenna 937 among a plurality of circuits included in the wireless communication interface 933 (for example, circuits for different wireless communication systems).
- Each of the antennas 937 has a single or a plurality of antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna), and is used for transmission / reception of a radio signal by the radio communication interface 933.
- the car navigation device 920 may have a plurality of antennas 937 as shown in FIG. 22 shows an example in which the car navigation device 920 includes a plurality of antennas 937, the car navigation device 920 may include a single antenna 937.
- the car navigation device 920 may include an antenna 937 for each wireless communication method.
- the antenna switch 936 may be omitted from the configuration of the car navigation device 920.
- the battery 938 supplies power to each block of the car navigation device 920 shown in FIG. 22 through a power supply line partially shown by a broken line in the drawing. Further, the battery 938 stores electric power supplied from the vehicle side.
- the communication control unit 141 described with reference to FIG. 11 may be implemented in the wireless communication interface 933. Further, at least a part of this function may be implemented in the processor 921.
- the technology according to the present disclosure may be realized as an in-vehicle system (or vehicle) 940 including one or more blocks of the car navigation device 920 described above, an in-vehicle network 941, and a vehicle side module 942.
- vehicle-side module 942 generates vehicle-side data such as vehicle speed, engine speed, or failure information, and outputs the generated data to the in-vehicle network 941.
- the wireless communication function is configured such that synchronization is performed in CC2 by a synchronization signal transmitted in CC2 synchronized with CC1, and synchronization is performed in CC1 using a synchronization result in CC2. Is controlled.
- CC1 is also synchronized with CC3. Then, before the wireless communication function is not synchronized in CC2 by the synchronization signal, synchronization is performed in CC3 by the synchronization signal transmitted in CC3, and synchronization is performed in CC1 using the synchronization result in CC3.
- the wireless communication function is controlled.
- the UE 100 since the primary anchor point is switched from CC2 to CC3 before the UE 100 becomes unsynchronized at CC2, the UE 100 is synchronized by CRS at CC3 even after it becomes unsynchronized by CRS at CC2. It becomes possible to continue taking. Therefore, the UE 100 can continue to synchronize with the slave (CC1) using the synchronization result at the primary anchor point. As a result, the communication quality of radio communication by the UE 100 in the slave (CC1) is further stabilized.
- CC1 is a CC in which a synchronization signal is not transmitted in at least one of the subframes which is a unit of time in wireless communication.
- the number of synchronization signals transmitted by CC1 is less than the number of synchronization signals transmitted by CC2 and CC3.
- the UE 100 synchronizes at CC1 using the synchronization result by CRS at the primary anchor point (CC2 or CC3) instead of individually synchronizing by CRS at CC1, thereby enabling more at CC1. Synchronize with high accuracy. As a result, the communication quality of radio communication by the UE 100 in CC1 becomes more stable.
- the synchronization signal transmitted in CC1 is less than the synchronization signal required for synchronization in CC1.
- the UE 100 cannot individually synchronize by CRS in CC1, but can synchronize in CC1 by using the synchronization result by CRS in the primary anchor point (CC2 or CC3). Become.
- CC1 as a slave is a CC used in the picocell 31.
- the pico cell 31 is a narrow area, it may be difficult to synchronize by CRS in the CC used in the pico cell 31 due to the movement of the UE 100. That is, when the UE 100 moves, the communication quality of radio communication in the CC used in the pico cell 31 is less stable.
- the synchronization result at the anchor point is used for the CC (that is, the slave) of the pico cell 31, so that the synchronization accuracy in the CC used in the pico cell 31 can be improved. As a result, the communication quality of radio communication by the UE 100 in CC1 can be more stable.
- the synchronization result in another CC is used for the CC used in the pico cell 31, it is possible to transmit no CRS in the pico cell 31 or reduce the amount of CRS transmitted in the pico cell 31. As a result, the throughput in the pico cell 31 can be improved.
- CC2 and CC3 are CCs used in the same cell.
- the UE 100 may be able to synchronize by CRS in CC3 that is the secondary anchor point even in a region where it is difficult to synchronize by CRS in CC2 that is the primary anchor point. Therefore, the UE 100 can further stabilize the communication quality of radio communication performed by the UE 100 by using CCs used in the same cell as the primary anchor point and the secondary anchor point.
- CCs used in different cells are not synchronized with each other, even when the UE 100 cannot receive signals of different cells, the UE 100 uses the CCs synchronized with each other as anchor points in the UE 100. , Communication quality in CC1 can be further stabilized.
- CCs used in cells adjacent to each other are CCs used in different cells.
- CC2 is a CC used in the first cell
- CC3 is a CC used in a second cell adjacent to the first cell.
- CC2 may be a CC used in a certain cell
- CC3 may be a CC used in another cell.
- CRS CRS
- CC used in macro cell and CC used in pico cell are CCs used in different cells.
- CC2 is one of the CC used in the picocell 31 and the CC used in the macrocell 21.
- CC3 is the other CC among the CC used in the picocell 31 and the CC used in the macrocell 21.
- CC 2 is a CC used in the pico cell 31
- CC 3 is a CC used in the macro cell 21.
- the UE 100 can synchronize with a new primary anchor point with high probability. Therefore, the communication quality of the radio communication by UE100 in CC1 can be stabilized more.
- CC2 is a CC used in the macrocell 21
- CC3 is a CC used in the picocell 31.
- the UE 100 can synchronize at the new primary anchor point. Therefore, the communication quality of the radio communication by UE100 in CC1 can be stabilized more.
- -Switching timing of primary anchor point For example, when the accuracy of synchronization in CC2 satisfies a predetermined switching condition, synchronization is performed in CC3, and synchronization is performed in CC1 using the synchronization result in CC3.
- the communication function is controlled.
- the predetermined switching condition includes that the accuracy of synchronization in CC2 is lower than the accuracy of synchronization in CC3.
- the UE 100 can synchronize with higher accuracy in the slave (CC1). As a result, the communication quality of radio communication by the UE 100 in the slave (CC1) is further stabilized.
- the predetermined switching condition may include that the accuracy of synchronization in CC2 is lower than a predetermined accuracy.
- the UE 100 can synchronize with a certain degree of accuracy in the slave (CC1). As a result, the communication quality of radio communication by the UE 100 in the slave (CC1) is further stabilized. Moreover, since the object of acquisition and monitoring of synchronization is limited to the primary anchor point, the load on the UE 100 can be further suppressed.
- -Search for new anchor point For example, when a predetermined search condition is satisfied, another CC that is synchronized with CC1 other than CC2 and CC3 is searched.
- the communication control unit 141 does not cause the UE 100 to be in a connection state for radio resources in at least one of CC2 and CC3.
- the resource consumption in the eNodeB using at least one CC is suppressed. More specifically, if the CC becomes RRC_Connected, resources in the eNodeB that uses the CC may be consumed. For example, in the eNodeB, memory resources for holding data addressed to the UE 100, radio resources for signaling to the UE 100, processing resources for signaling to the UE 100, and the like can be consumed. Therefore, as described above, if the UE 100 does not become RRC_Connected, consumption of the resources can be suppressed.
- the communication control unit 141 stops using CC1 when a predetermined end condition is satisfied.
- the predetermined termination condition includes that the accuracy of synchronization in any CC synchronized with CC1 is lower than the predetermined accuracy.
- a CC that is, a slave
- a small cell that is, a pico cell
- the present disclosure is not limited to such an example.
- the slave may be a CC used in a macro cell.
- a plurality of CCs may be secondary anchor points. That is, a plurality of secondary anchor points may be prepared. In this case, any CC that is the secondary anchor point (for example, the CC with the highest synchronization accuracy) may then become the primary anchor point.
- the searched CC may be added as a new secondary anchor point.
- the wireless communication function for obtaining synchronization is the wireless communication unit of the UE
- the present disclosure is not limited to such an example.
- the radio communication function may be included in the control unit of the UE, or may be distributed in the radio communication unit and the control unit of the UE.
- the communication control function may be a function of another device connected directly or indirectly to the UE.
- frequency bands synchronized with each other have been described as indicating that they are synchronized with each other in both the time direction and the frequency direction, the present disclosure is limited to such examples.
- the frequency bands synchronized with each other may be frequency bands synchronized in the time direction.
- the frequency bands synchronized with each other may be frequency bands synchronized in the frequency direction.
- the frequency bands synchronized with each other may be frequency bands synchronized in either the time direction or the frequency direction.
- the pico cell was mentioned as an example of a small cell, this indication is not limited to the example which concerns.
- the small cell may be another cell (for example, a nano cell, a femto cell, or the like) that partially or entirely overlaps with the macro cell, instead of the pico cell.
- the communication system may be a system that complies with another standard in 3GPP.
- the communication system may be a system that conforms to a future standard in 3GPP.
- processing steps in the communication control processing of this specification do not necessarily have to be executed in time series in the order described in the flowchart.
- the processing steps in the communication control process may be executed in an order different from the order described in the flowchart, or may be executed in parallel.
- a computer program for causing hardware such as a CPU, ROM, and RAM incorporated in a terminal device (for example, UE) to exhibit functions equivalent to the respective configurations of the terminal device.
- a storage medium storing the computer program is also provided.
- Synchronization is performed in the second frequency band by a synchronization signal transmitted in a second frequency band that is synchronized with the first frequency band, and the first result is obtained using a synchronization result in the second frequency band.
- a communication control unit for controlling the wireless communication function so as to synchronize in the frequency band of The first frequency band is synchronized with a third frequency band;
- the communication control unit uses the synchronization signal transmitted in the third frequency band before the wireless communication function is not synchronized in the second frequency band by the synchronization signal.
- the wireless communication function is controlled so as to synchronize in the first frequency band using the synchronization result in the third frequency band Terminal device.
- the first frequency band is a frequency band in which a synchronization signal is not transmitted in at least one of the subframes that are units of time in wireless communication.
- the synchronization signal transmitted in the first frequency band is less than the synchronization signal transmitted in each of the second frequency band and the third frequency band. .
- a synchronization signal transmitted in the first frequency band is less than a synchronization signal required for synchronization in the first frequency band.
- the terminal device according to any one of (1) to (5), wherein the second frequency band and the third frequency band are frequency bands used in the same cell.
- the terminal device according to any one of (1) to (5), wherein the second frequency band and the third frequency band are frequency bands used in different cells.
- the second frequency band is a frequency band used in the first cell;
- the third frequency band is a frequency band used in a second cell adjacent to the first cell.
- the terminal device according to (7).
- the second frequency band is one of a frequency band used in a small cell partially or entirely overlapped with a macro cell, and a frequency band used in the macro cell,
- the third frequency band is the other one of the frequency band used in the small cell and the frequency band used in the macro cell.
- the terminal device according to (7).
- the second frequency band is a frequency band used in the small cell
- the third frequency band is a frequency band used in the macro cell.
- (11) The second frequency band is a frequency band used in the macro cell;
- the third frequency band is a frequency band used in the small cell.
- the terminal device according to (9). (12) When the accuracy of synchronization in the second frequency band satisfies a predetermined switching condition, the communication control unit synchronizes in the third frequency band and uses a synchronization result in the third frequency band.
- the communication control unit searches for another frequency band synchronized with the first frequency band other than the second frequency band and the third frequency band when a predetermined search condition is satisfied, The terminal device according to any one of 1) to (14). (16) The communication control unit, when a fourth frequency band is searched for as the other frequency band, before the wireless communication function cannot be synchronized in the second frequency band by the synchronization signal.
- the synchronizing signal transmitted in the fourth frequency band is synchronized in the fourth frequency band, and the synchronization result in the fourth frequency band is used to
- the terminal device according to (15) wherein the wireless communication function is controlled so as to synchronize in the first frequency band.
- the communication control unit stops using the first frequency band when a predetermined termination condition is satisfied,
- the predetermined termination condition includes that the accuracy of synchronization in any frequency band synchronized with the first frequency band is lower than the predetermined accuracy.
- a communication control method Synchronization is performed in the second frequency band by a synchronization signal transmitted in a second frequency band that is synchronized with the first frequency band, and the first result is obtained using a synchronization result in the second frequency band.
- Controlling the wireless communication function to synchronize in the frequency band of The first frequency band is synchronized with a third frequency band;
- the communication control method includes: Before the wireless communication function is not synchronized in the second frequency band by the synchronization signal, the wireless communication function is synchronized in the third frequency band by the synchronization signal transmitted in the third frequency band.
- a communication control method further comprising controlling the wireless communication function so as to synchronize in the first frequency band using a synchronization result in a third frequency band.
- Communication System 21 Macro Cell 31 Pico Cell 100 UE (User Equipment) 120 wireless communication unit 151 communication control unit 200 macro eNodeB 300 pico eNodeB
Abstract
Description
1.3GPPにおける無線通信の技術
2.本開示の実施形態に係る技術的課題
2.1.周波数帯域間の同期に関する考察
2.2.技術的課題
3.本実施形態に係る通信システムの概略的な構成
4.UEの構成
5.処理の流れ
6.応用例
7.まとめ
まず、前提として、3GPPにおける無線通信の技術を説明する。
-コンポーネントキャリア
リリース10のキャリアアグリゲーションでは、最大で5つのコンポーネントキャリア(CC)が束ねられて、UEにより使用される。各CCは、最大20MHz幅の帯域である。キャリアアグリゲーションでは、周波数方向で連続するCCが使用される場合と、周波数方向で離れたCCが使用される場合とがある。キャリアアグリゲーションでは、使用されるCCをUE毎に設定することが可能である。
キャリアアグリゲーションでは、UEにより使用される複数のCCのうちの1つが特別なCCである。当該1つの特別なCCは、PCC(Primary Component Carrier)と呼ばれる。また、上記複数のCCのうちの残りは、SCC(Secondary Component Carrier)と呼ばれる。PCCは、UEによって異なり得る。以下、この点について図1を参照してより具体的に説明する。
キャリアアグリゲーションでは、各CCで共通リファレンス信号(Common Reference Signal:CRS)が送信される。そして、UEは、当該CRSにより、各CCにおいて同期をとる。本明細書では、「(UEがCCにおいて)同期をとる(Synchronize)」とは、UEが、CCにいて信号を正しく受信できるように信号の受信におけるタイミング及び/又は周波数を調整すること(例えば、同期追跡)を意味する。なお、共通リファレンス信号は、セル固有のリファレンス信号(Cell-specific Reference Signal)とも呼ばれる。
キャリアアグリゲーションでは、後方互換性(Backward Compatibility)の確保の観点から、各CCがLegacy UE(即ち、従来型のUE)により使用可能であることが前提であった。しかし、Legacy UEが使用できないもののより効率的であるCCの定義が、検討され始めている。即ち、NCT(New Carrier Type)又は追加キャリア(Additional Carrier)と呼ばれる新たなCCの定義が、検討され始めている。
-NCTの種類
リリース11において検討されたNCTには、大きく分けて2種類のNCTがある。
Legacy CCで送信されるCRSは、UEが同期をとれるようにするためだけではなく、受信信号の復調のためにも送信されるので、冗長である。一方、リリース10以降のリリースでは、復調のためのRSとしてCIS-RSが規格化されたので、CRSを削減することが可能である。そこで、UEが継続的に同期をとることを可能にしつつCRSをどれだけ削除できるかが、検討された。とりわけ、Unsynchronized NCT(即ち、UNCT)のCRSの削減として、周波数方向におけるCRSの削減と、時間方向におけるCRSの削減が検討された。
一方、Synchronized NCT(SNCT)は、Legacy CCと同期しているので、基本的には、SNCTにおいては、従来のCRSを削除してしまうことが可能である。
UEは、UEが同期をとれているか否かを、PDCCH(Physical Downlink Control CHannel)のブロックエラーレート(Block Error Rate:BLER)に基づいて監視する。換言すると、UEは、PDCCHのBLERに基づいて、UEの同期外れを検出する。例えば、PDCCHのBLERが10%以上になった場合に、UEは同期外れを検出する。
リリース12のNCTは、3GPP RAN #57 Plenary meetingにおいて、RP-121415として、2012年9月に承認された検討事項(Study Item:SI)である。このSIは、フェーズ1とフェーズ2とに分かれる。フェーズ1では、リリース11のNCTの強化(Enhancement)についての検討が行われ、フェーズ2では、スモールセルのシナリオを考慮した検討が行われる予定である。なお、スモールセルは、具体的には、例えば、ピコセル、ナノセル、フェムトセル等である。本明細書では、スモールセルの具体例としてピコセルを挙げて説明する。
eNodeBは、UEへ制御情報を提供する際に、例えば、システム情報(System Information)又はRRC(Radio Resource Control)シグナリングを用いる。以下、図7を参照して、これらの2つの提供手法の特徴を説明する。
続いて、本開示の実施形態に係る技術的課題を説明する。
まず、周波数帯域間の同期に関する考察を説明する。
ここでは、周波数帯域間での同期をより具体的に説明する。周波数帯域間の同期として、時間方向での同期(以下、「時間同期」と呼ぶ)と、周波数方向での同期(以下、「周波数同期」と呼ぶ)とがある。以下、この点について図8及び図9を参照して具体例を説明する。
ケース1:時間同期及び周波数同期の両方がある
ケース2:時間同期があるが、周波数同期はない
ケース3:時間同期はないが、周波数同期はある
ケース4:時間同期及び周波数領域の両方がない
また、別の観点として、周波数帯域間の同期として、eNodeB側(即ち、ネットワーク側)での同期とUEでの同期とがある。そして、2つのCCについて、eNodeB側で時間同期及び周波数同期があるとしても、UEが当該2つのCCで信号を受信する際に、UE側で時間同期及び周波数同期があるかは不明である。
次に、技術的課題を説明する。
上述したように、3GPPのリリース11では、後方互換性を維持できるLegacy CC(従来型のCC)とは別に、新たなコンポーネントキャリアとして、NCTが検討されている。ここでは、NCTは、新たなCCの型(type)のことを意味するとともに、当該型のCCのことも意味するものとする。そして、NCTとして、Legacy CCと同期しているNCT(即ち、SNCT)と、Legacy CCと同期していないNCT(即ち、UNCT)とが、検討されている。
しかし、UEは、あるCCにおいてCRSにより同期をとり、当該あるCCにおける同期結果を利用して別のCCにおいて同期をとる場合に、当該あるCCにおいてCRSにより同期をとれなくなることもあり得る。そして、UEは、上記あるCCにおいて同期をとれなくなると、当該あるCCにおける同期結果を利用できなくなる。その結果、上記あるCCにおいて同期状態が失われると、上記別のCCでも同期状態が失われてしまう。即ち、UEによる無線通信の通信品質が損なわれる。
続いて、図10を参照して、本開示の実施形態に係る通信システムの概略的な構成を説明する。図10は、本開示の実施形態に係る通信システム1の概略的な構成の一例を示す説明図である。図1を参照すると、通信システム1は、UE100、マクロeNodeB200及びピコeNodeB300を含む。例えば、通信システム1は、LTE-Advancedに準拠したシステムである。
UE100は、マクセル21内でマクロeNodeB200との無線通信を行う。また、UE100は、ピコセル31内でピコeNodeB300との無線通信を行う。
マクロeNodeB200は、マクロセル21内に位置するUE100との無線通信を行う。また、マクロeNodeB200は、1つ以上のコンポーネントキャリア(CC)を用いて無線通信を行う。
ピコeNodeB300は、マクロセル21と一部又は全体で重なるピコセル31内に位置するUE100との無線通信を行う。また、ピコeNodeB300は、1つ以上のCCを用いて無線通信を行う。
続いて、図11~図19を参照して、本実施形態に係るUE100の構成を説明する。図11は、本実施形態に係るUE100の構成の一例を示すブロック図である。図11を参照すると、UE100は、アンテナ部110、無線通信部120、記憶部130及び制御部140を備える。
アンテナ部110は、無線信号を受信し、受信された無線信号を無線通信部120へ出力する。また、アンテナ部110は、無線通信部120により出力された送信信号を送信する。
無線通信部120は、UE100がマクロセル21に位置する場合に、マクロeNodeB200との無線通信を行う。また、無線通信部120は、UE100がピコセル31に位置する場合に、ピコeNodeB300との無線通信を行う。
記憶部130は、UE100の動作のためのプログラム及びデータを記憶する。
制御部140は、UE100の様々な機能を提供する。
通信制御部141は、UE100による無線通信を制御する。
とりわけ本実施形態では、通信制御部141は、第1のコンポーネントキャリア(CC)(以下、「CC1」と呼ぶ)と同期している第2のCC(以下、「CC2」と呼ぶ)で送信される同期用信号によりCC2において同期をとり、CC2における同期結果を利用してCC1において同期をとるように、無線通信機能を制御する。
さらに、とりわけ本実施形態では、CC1は、第3のCC(以下、「CC3」と呼ぶ)とも同期している。そして、通信制御部141は、上記無線通信機能が上記同期用信号によりCC2において同期をとれなくなる前に、CC3で送信される同期用信号によりCC3において同期をとり、CC3における同期結果を利用してCC1において同期をとるように、上記無線通信機能を制御する。
また、例えば、通信制御部141は、CC2における同期の精度が所定の切換え条件を満たす場合に、CC3において同期をとり、CC3における同期結果を利用してCC1において同期をとるように、無線通信機能を制御する。
第1の例として、上記所定の切換え条件は、CC2における同期の精度がCC3における同期の精度よりも低くなることを含む。この場合に、例えば、通信制御部141は、CC2における同期の精度がCC3における同期の精度よりも低くなる場合に、プライマリアンカーポイントをCC2からCC3へ切り替える。
第2の例として、上記所定の切換え条件は、CC2における同期の精度が所定の精度よりも低くなることを含んでもよい。この場合に、例えば、通信制御部141は、CC2における同期の精度が所定の精度よりも低くなる場合に、プライマリアンカーポイントをCC2からCC3へ切り替えてもよい。
例えば、CC1は、無線通信での時間の単位であるサブフレームのうちの少なくともいずれかのサブフレームでは同期用信号が送信されないCCである。例えば、CC1は、いずれかのサブフレームではCRSが送信されないCCである。即ち、CC1は、NCTである。
--スレーブが用いられるセル
例えば、スレーブであるCC1は、ピコセル31で用いられるCCである。
スレーブに対するプライマリアンカーポイント及びセカンダリアンカーポイント(即ち、CC2及びCC3)については、以下のように様々なケースがあり得る。
ケース1:同一セル(ピコセル)で用いられるCC
ケース2:同一セル(マクロセル)で用いられるCC
ケース3:互いに隣接するセル(ピコセル)の一方で用いられるCC、及び他方で用いられるCC
ケース4:互いに隣接するセル(マクロセル)の一方で用いられるCC、及び他方で用いられるCC
ケース5:マクロセルで用いられるCC、及びピコセルで用いられるCC
例えば、CC2及びCC3は、同一のセルで用いられるCCである。
例えば、CC2及びCC3は、別々のセルで用いられるCCである。さらに、例えば、CC2は、第1のセルにおいて用いられるCCであり、CC3は、上記第1のセルに隣接する第2のセルにおいて用いられるCCである。
例えば、CC2及びCC3は、別々のセルで用いられるCCである。さらに、例えば、CC2は、ピコセル31で用いられるCC、及びマクロセル21で用いられるCCのうちの、一方のCCである。また、CC3は、ピコセル31で用いられるCC、及びマクロセル21で用いられるCCのうちの、他方のCCである。これは、上記ケース5に該当する。
また、例えば、通信制御部141は、所定の探索条件が満たされる場合に、CC2及びCC3以外の、CC1と同期する別のCCを探索する。即ち、通信制御部141は、新たなアンカーポイントの候補を探索する。
また、例えば、通信制御部141は、所定の終了条件が満たされる場合に、CC1の使用を停止する。当該所定の終了条件は、CC1に同期しているいずれのCCにおける同期の精度も所定の精度よりも低くなることを含む。
また、例えば、通信制御部141は、CC2及びCC3の少なくとも一方のCCにおいてUE100を無線リソースについての接続状態にさせない。以下、この点について、図19を参照して具体例を説明する。
次に、図20を参照して、本実施形態に係る通信制御処理の一例を説明する。図20は、本実施形態に係る通信制御処理の概略的な流れの一例を示すフローチャートである。
本開示に係る技術は、様々な製品へ応用可能である。例えば、UE100は、スマートフォン、タブレットPC(Personal Computer)、ノートPC、携帯型ゲーム端末、携帯型/ドングル型のモバイルルータ若しくはデジタルカメラなどのモバイル端末、又はカーナビゲーション装置などの車載端末として実現されてもよい。また、UE100は、M2M(Machine To Machine)通信を行う端末(MTC(Machine Type Communication)端末ともいう)として実現されてもよい。さらに、UE100は、これら端末に搭載される無線通信モジュール(例えば、1つのダイで構成される集積回路モジュール)であってもよい。
図21は、本開示に係る技術が適用され得るスマートフォン900の概略的な構成の一例を示すブロック図である。スマートフォン900は、プロセッサ901、メモリ902、ストレージ903、外部接続インタフェース904、カメラ906、センサ907、マイクロフォン908、入力デバイス909、表示デバイス910、スピーカ911、無線通信インタフェース912、1つ以上のアンテナスイッチ915、1つ以上のアンテナ916、バス917、バッテリー918及び補助コントローラ919を備える。
図22は、本開示に係る技術が適用され得るカーナビゲーション装置920の概略的な構成の一例を示すブロック図である。カーナビゲーション装置920は、プロセッサ921、メモリ922、GPS(Global Positioning System)モジュール924、センサ925、データインタフェース926、コンテンツプレーヤ927、記憶媒体インタフェース928、入力デバイス929、表示デバイス930、スピーカ931、無線通信インタフェース933、1つ以上のアンテナスイッチ936、1つ以上のアンテナ937及びバッテリー938を備える。
ここまで、図10~図20を用いて、本開示の実施形態に係る通信装置及び各処理を説明した。本開示に係る実施形態によれば、CC1と同期しているCC2で送信される同期用信号によりCC2において同期をとり、CC2における同期結果を利用してCC1において同期をとるように、無線通信機能が制御される。また、CC1は、CC3とも同期している。そして、上記無線通信機能が上記同期用信号によりCC2において同期をとれなくなる前に、CC3で送信される同期用信号によりCC3において同期をとり、CC3における同期結果を利用してCC1において同期をとるように、上記無線通信機能が制御される。
また、例えば、CC1は、無線通信での時間の単位であるサブフレームのうちの少なくともいずれかのサブフレームでは同期用信号が送信されないCCである。
--スレーブが用いられるセル
また、例えば、スレーブであるCC1は、ピコセル31で用いられるCCである。
---同一のセルで用いられるCC
一例として、CC2及びCC3は、同一のセルで用いられるCCである。
また、別の例として、CC2及びCC3は、別々のセルで用いられるCCである。そして、例えば、CC2は、第1のセルにおいて用いられるCCであり、CC3は、上記第1のセルに隣接する第2のセルにおいて用いられるCCである。
また、別の例として、CC2及びCC3は、別々のセルで用いられるCCである。そして、例えば、CC2は、ピコセル31で用いられるCC、及びマクロセル21で用いられるCCのうちの、一方のCCである。また、CC3は、ピコセル31で用いられるCC、及びマクロセル21で用いられるCCのうちの、他方のCCである。
また、例えば、CC2における同期の精度が所定の切換え条件を満たす場合に、CC3において同期をとり、CC3における同期結果を利用してCC1において同期をとるように、無線通信機能が制御される。
第1の例として、上記所定の切換え条件は、CC2における同期の精度がCC3における同期の精度よりも低くなることを含む。
第2の例として、上記所定の切換え条件は、CC2における同期の精度が所定の精度よりも低くなることを含んでもよい。
また、例えば、所定の探索条件が満たされる場合に、CC2及びCC3以外の、CC1と同期する別のCCを探索する。
また、例えば、通信制御部141は、CC2及びCC3の少なくとも一方のCCにおいてUE100を無線リソースについての接続状態にさせない。
また、例えば、通信制御部141は、所定の終了条件が満たされる場合に、CC1の使用を停止する。当該所定の終了条件は、CC1に同期しているいずれのCCにおける同期の精度も所定の精度よりも低くなることを含む。
(1)
第1の周波数帯域と同期している第2の周波数帯域で送信される同期用信号により当該第2の周波数帯域において同期をとり、当該第2の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、無線通信機能を制御する通信制御部
を備え、
前記第1の周波数帯域は、第3の周波数帯域と同期し、
前記通信制御部は、前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域で送信される同期用信号により当該第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、
端末装置。
(2)
前記第1の周波数帯域は、無線通信での時間の単位であるサブフレームのうちの少なくともいずれかのサブフレームでは同期用信号が送信されない周波数帯域である、前記(1)に記載の端末装置。
(3)
前記第1の周波数帯域で送信される同期用信号は、前記第2の周波数帯域及び前記第3の周波数帯域の各々で送信される同期用信号よりも少ない、前記(2)に記載の端末装置。
(4)
前記第1の周波数帯域で送信される同期用信号は、当該第1の周波数帯域において同期をとるのに要する同期用信号よりも少ない、前記(3)に記載の端末装置。
(5)
前記第1の周波数帯域は、マクロセルと一部又は全体で重なるスモールセルで用いられる周波数帯域である、前記(1)~(4)のいずれか1項に記載の端末装置。
(6)
前記第2の周波数帯域及び前記第3の周波数帯域は、同一のセルで用いられる周波数帯域である、前記(1)~(5)のいずれか1項に記載の端末装置。
(7)
前記第2の周波数帯域及び前記第3の周波数帯域は、別々のセルで用いられる周波数帯域である、前記(1)~(5)のいずれか1項に記載の端末装置。
(8)
前記第2の周波数帯域は、第1のセルにおいて用いられる周波数帯域であり、
前記第3の周波数帯域は、前記第1のセルに隣接する第2のセルにおいて用いられる周波数帯域である、
前記(7)に記載の端末装置。
(9)
前記第2の周波数帯域は、マクロセルと一部又は全体で重なるスモールセルにおいて用いられる周波数帯域、及び前記マクロセルにおいて用いられる周波数帯域のうちの、一方の周波数帯域であり、
前記第3の周波数帯域は、前記スモールセルにおいて用いられる周波数帯域、及び前記マクロセルにおいて用いられる周波数帯域のうちの、他方の周波数帯域である、
前記(7)に記載の端末装置。
(10)
前記第2の周波数帯域は、前記スモールセルで用いられる周波数帯域であり、
前記第3の周波数帯域は、前記マクロセルで用いられる周波数帯域である、
前記(9)に記載の端末装置。
(11)
前記第2の周波数帯域は、前記マクロセルで用いられる周波数帯域であり、
前記第3の周波数帯域は、前記スモールセルで用いられる周波数帯域である、
前記(9)に記載の端末装置。
(12)
前記通信制御部は、前記第2の周波数帯域における同期の精度が所定の切換え条件を満たす場合に、前記第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、前記(1)~(11)のいずれか1項に記載の端末装置。
(13)
前記所定の切換え条件は、前記第2の周波数帯域における同期の精度が前記第3の周波数帯域における同期の精度よりも低くなることを含む、前記(12)に記載の端末装置。
(14)
前記所定の切換え条件は、前記第2の周波数帯域における同期の精度が所定の精度よりも低くなることを含む、前記(12)又は(13)に記載の端末装置。
(15)
前記通信制御部は、所定の探索条件が満たされる場合に、前記第2の周波数帯域及び第3の周波数帯域以外の、前記第1の周波数帯域と同期する別の周波数帯域を探索する、前記(1)~(14)のいずれか1項に記載の端末装置。
(16)
前記通信制御部は、前記別の周波数帯域として第4の周波数帯域が探索された場合に、前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域において同期をとる代わりに、前記第4の周波数帯域で送信される同期用信号により当該第4の周波数帯域において同期をとり、当該第4の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、前記(15)に記載の端末装置。
(17)
前記通信制御部は、前記第2の周波数帯域及び前記第3の周波数帯域の少なくとも一方の周波数帯域において前記端末装置を無線リソースについての接続状態にさせない、前記(1)~(16)のいずれか1項に記載の端末装置。
(18)
前記通信制御部は、所定の終了条件が満たされる場合に、前記第1の周波数帯域の使用を停止し、
前記所定の終了条件は、前記第1の周波数帯域に同期しているいずれの周波数帯域における同期の精度も所定の精度よりも低くなることを含む、
(1)~(17)のいずれか1項に記載の端末装置。
(19)
コンピュータを、
第1の周波数帯域と同期している第2の周波数帯域で送信される同期用信号により当該第2の周波数帯域において同期をとり、当該第2の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、無線通信機能を制御する通信制御部
として機能させ、
前記第1の周波数帯域は、第3の周波数帯域と同期し、
前記通信制御部は、前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域で送信される同期用信号により当該第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、
プログラム。
(20)
通信制御方法であって、
第1の周波数帯域と同期している第2の周波数帯域で送信される同期用信号により当該第2の周波数帯域において同期をとり、当該第2の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、無線通信機能を制御すること
を含み、
前記第1の周波数帯域は、第3の周波数帯域と同期し、
前記通信制御方法は、
前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域で送信される同期用信号により当該第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御こと
をさらに含む、通信制御方法。
21 マクロセル
31 ピコセル
100 UE(User Equipment)
120 無線通信部
151 通信制御部
200 マクロeNodeB
300 ピコeNodeB
Claims (20)
- 第1の周波数帯域と同期している第2の周波数帯域で送信される同期用信号により当該第2の周波数帯域において同期をとり、当該第2の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、無線通信機能を制御する通信制御部
を備え、
前記第1の周波数帯域は、第3の周波数帯域と同期し、
前記通信制御部は、前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域で送信される同期用信号により当該第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、
端末装置。 - 前記第1の周波数帯域は、無線通信での時間の単位であるサブフレームのうちの少なくともいずれかのサブフレームでは同期用信号が送信されない周波数帯域である、請求項1に記載の端末装置。
- 前記第1の周波数帯域で送信される同期用信号は、前記第2の周波数帯域及び前記第3の周波数帯域の各々で送信される同期用信号よりも少ない、請求項2に記載の端末装置。
- 前記第1の周波数帯域で送信される同期用信号は、当該第1の周波数帯域において同期をとるのに要する同期用信号よりも少ない、請求項3に記載の端末装置。
- 前記第1の周波数帯域は、マクロセルと一部又は全体で重なるスモールセルで用いられる周波数帯域である、請求項1に記載の端末装置。
- 前記第2の周波数帯域及び前記第3の周波数帯域は、同一のセルで用いられる周波数帯域である、請求項1に記載の端末装置。
- 前記第2の周波数帯域及び前記第3の周波数帯域は、別々のセルで用いられる周波数帯域である、請求項1に記載の端末装置。
- 前記第2の周波数帯域は、第1のセルにおいて用いられる周波数帯域であり、
前記第3の周波数帯域は、前記第1のセルに隣接する第2のセルにおいて用いられる周波数帯域である、
請求項7に記載の端末装置。 - 前記第2の周波数帯域は、マクロセルと一部又は全体で重なるスモールセルにおいて用いられる周波数帯域、及び前記マクロセルにおいて用いられる周波数帯域のうちの、一方の周波数帯域であり、
前記第3の周波数帯域は、前記スモールセルにおいて用いられる周波数帯域、及び前記マクロセルにおいて用いられる周波数帯域のうちの、他方の周波数帯域である、
請求項7に記載の端末装置。 - 前記第2の周波数帯域は、前記スモールセルで用いられる周波数帯域であり、
前記第3の周波数帯域は、前記マクロセルで用いられる周波数帯域である、
請求項9に記載の端末装置。 - 前記第2の周波数帯域は、前記マクロセルで用いられる周波数帯域であり、
前記第3の周波数帯域は、前記スモールセルで用いられる周波数帯域である、
請求項9に記載の端末装置。 - 前記通信制御部は、前記第2の周波数帯域における同期の精度が所定の切換え条件を満たす場合に、前記第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、請求項1に記載の端末装置。
- 前記所定の切換え条件は、前記第2の周波数帯域における同期の精度が前記第3の周波数帯域における同期の精度よりも低くなることを含む、請求項12に記載の端末装置。
- 前記所定の切換え条件は、前記第2の周波数帯域における同期の精度が所定の精度よりも低くなることを含む、請求項12に記載の端末装置。
- 前記通信制御部は、所定の探索条件が満たされる場合に、前記第2の周波数帯域及び第3の周波数帯域以外の、前記第1の周波数帯域と同期する別の周波数帯域を探索する、請求項1に記載の端末装置。
- 前記通信制御部は、前記別の周波数帯域として第4の周波数帯域が探索された場合に、前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域において同期をとる代わりに、前記第4の周波数帯域で送信される同期用信号により当該第4の周波数帯域において同期をとり、当該第4の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、請求項15に記載の端末装置。
- 前記通信制御部は、前記第2の周波数帯域及び前記第3の周波数帯域の少なくとも一方の周波数帯域において前記端末装置を無線リソースについての接続状態にさせない、請求項1に記載の端末装置。
- 前記通信制御部は、所定の終了条件が満たされる場合に、前記第1の周波数帯域の使用を停止し、
前記所定の終了条件は、前記第1の周波数帯域に同期しているいずれの周波数帯域における同期の精度も所定の精度よりも低くなることを含む、
請求項1に記載の端末装置。 - コンピュータを、
第1の周波数帯域と同期している第2の周波数帯域で送信される同期用信号により当該第2の周波数帯域において同期をとり、当該第2の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、無線通信機能を制御する通信制御部
として機能させ、
前記第1の周波数帯域は、第3の周波数帯域と同期し、
前記通信制御部は、前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域で送信される同期用信号により当該第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御する、
プログラム。 - 通信制御方法であって、
第1の周波数帯域と同期している第2の周波数帯域で送信される同期用信号により当該第2の周波数帯域において同期をとり、当該第2の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、無線通信機能を制御すること
を含み、
前記第1の周波数帯域は、第3の周波数帯域と同期し、
前記通信制御方法は、
前記無線通信機能が前記同期用信号により前記第2の周波数帯域において同期をとれなくなる前に、前記第3の周波数帯域で送信される同期用信号により当該第3の周波数帯域において同期をとり、当該第3の周波数帯域における同期結果を利用して前記第1の周波数帯域において同期をとるように、前記無線通信機能を制御こと
をさらに含む、通信制御方法。
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