WO2012042736A1

WO2012042736A1 - Wireless communication apparatus, wireless communication system, and wireless communication terminal

Info

Publication number: WO2012042736A1
Application number: PCT/JP2011/004673
Authority: WO
Inventors: 尚志田村; 青山　高久; ヨヒムロエール
Original assignee: パナソニック株式会社
Priority date: 2010-09-30
Filing date: 2011-08-23
Publication date: 2012-04-05

Abstract

A wireless communication apparatus can communicate with a wireless communication terminal that performs a carrier aggregation by use of the component carriers of a plurality of communication cells having different synchronization timings. In a case where while the synchronization of an uplink has been established in a first component carrier that serves as a reference among the other ones of the plurality of component carriers used by the wireless communication terminal, the wireless communication terminal uses a second component carrier, which is associated with the first component carrier, to establish the synchronization of an uplink, the wireless communication apparatus uses an identifier, which is unique to the wireless communication terminal, to transmit, to the wireless communication terminal, an individual control signal including an adjustment value of the transmission timing of the wireless communication terminal. Therefore, when the wireless communication terminal, which performs a carrier aggregation, manages the synchronization timings of a plurality of uplinks, the wireless communication apparatus can quickly and efficiently perform a process to adjust the synchronization timings.

Description

Wireless communication device, wireless communication system, and wireless communication terminal

The present invention relates to a wireless communication device, a wireless communication system, and a wireless communication terminal that can communicate by using each component carrier of a plurality of communication cells simultaneously by carrier aggregation.

The standardization organization 3GPP (The 3rd Generation Generation Partnership Project) is promoting standardization of LTE (Long Term Term Evolution) as the next generation communication standard of W-CDMA (Wideband Code Division Multiple Access) (for example, Non-Patent Document 1). And 2).

In LTE, a wireless communication base station (E-UTRAN NodeB (eNB)) of a network (Evolved Universal Terrestrial Radio Access Network (E-UTRAN)) has a plurality of communication cells. A wireless communication terminal (User Equipment (UE)) belongs to one of the communication cells. Hereinafter, the radio communication base station (eNB) is simply referred to as “base station”, the communication cell is simply referred to as “cell”, and the radio communication terminal (UE) is simply referred to as “terminal”.

The standardization organization 3GPP is proceeding with standardization of LTE-Advanced (Long Term Evolution Advanced: LTE-A) as a next generation wireless communication standard compatible with LTE. In LTE-A, introduction of “Carrier Aggregation” in which a terminal simultaneously uses cells of a plurality of carrier frequencies is being studied. Note that the carrier aggregation is also called “band aggregation”.

FIG. 8A and FIG. 8B are diagrams showing examples of carrier aggregation. 8A and 8B, among the six component carriers whose carrier frequencies are f1, f2, f3, f4, f5, and f6, respectively, the carrier frequencies are f1, f2, f3, and f6, respectively. An example in which a terminal uses four component carriers at the same time is shown. Thus, the use of a plurality of component carriers is expected to improve the throughput of communication between the terminal and the base station.

FIGS. 9A to 9E are schematic diagrams showing a plurality of cells managed by a base station as a network entity. In the carrier aggregation, each component carrier of a plurality of cells is used at the same time, but there are various modes for combinations of a plurality of cells to be used. In the example shown in FIGS. 9A to 9C, one base station has three cells (cell 1, cell 2, cell 3) corresponding to the carrier frequency f1, and 3 corresponding to the carrier frequency f2. One cell (cell 4, cell 5, cell 6) is managed. In the example shown in FIG. 9D, one base station manages three cells (cell 1, cell 2, cell 3) corresponding to the carrier frequency f1. In the example shown in FIG. 9E, the base station manages three cells (cell 1, cell 2, cell 3) corresponding to the carrier frequency f1, and RRH (Remote Radio Head) corresponds to the carrier frequency f2. Three cells (cell 4, cell 5, cell 6) are managed.

As a mode of simultaneously using a plurality of component carriers having different carrier frequencies belonging to the same base station, as shown in FIG. 9A, a plurality of component carriers having different carrier frequencies belonging to the same geographical area of the same base station can be used simultaneously. In some cases, as shown in FIG. 9B, component carriers having a plurality of different carrier frequencies belonging to different geographical areas of the same base station may be used at the same time. Also, as shown in FIG. 9 (c), carrier aggregation is possible even when managing cells of different geographical sizes at different carrier frequencies of the same base station. Furthermore, as shown in FIG. 9D, a plurality of component carriers having the same carrier frequency belonging to different geographical areas of the same base station may be used at the same time. Furthermore, as shown in FIG. 9E, component carriers of different carrier frequencies of different network entities (base station and RRH) may be used at the same time.

The “network entity” includes a base station (eNB) and an RRH (Remote Radio Head) installed in an area away from the base station, as well as a relay node (relay node (Relay node) connected wirelessly from the base station. ) Or repeater) or femto base stations. Note that the network entity may be called a wireless communication device. The RRH has the same function as the radio unit (Radio-Frequency unit: RF unit) of the base station, and is connected to the control unit of the base station by a wired cable.

In this specification, a case where a plurality of component carriers having different carrier frequencies of the same network entity are used simultaneously as shown in FIGS. 9A to 9C, and a single network entity as shown in FIG. The case where a plurality of component carriers of the same carrier frequency are used at the same time and the case where a plurality of component carriers of different carrier frequencies of different network entities are used simultaneously as shown in FIG. .

FIG. 10 is a diagram illustrating an example when the terminal has a plurality of uplink synchronization timings in the aspect illustrated in FIG. In the example shown in FIG. 10, a base station and an RRH (Remote Radio Radio Head) are provided as network entities to which a terminal can be connected. The base station manages cell 1, cell 2 and cell 3 of carrier frequency f1. RRH manages cell 4, cell 5 and cell 6 of carrier frequency f2. The terminal performs carrier aggregation using the cell 2 of the carrier frequency f1 and the cell 6 of the carrier frequency f2.

Each network entity needs to receive packets from all terminals connected to the network entity at the same timing so that packets transmitted on the uplink from each terminal connected to the network entity do not interfere with each other. is there. FIG. 11 is a diagram illustrating an example when the terminal uses component carriers of a plurality of carrier frequencies. As shown in FIG. 11, the terminal uses two cells of carrier frequencies f1 and f2 managed by the base station and one cell of carrier frequency f3 managed by the RRH at the same time. For example, the terminal uses the same uplink timing for each component carrier of the carrier frequencies f1 and f2. That is, the terminal groups component carriers having the same uplink timing (see Non-Patent Document 3). At this time, the terminal may use uplink timing different from that of the component carriers of the carrier frequencies f1 and f2 for the component carrier of the carrier frequency f3.

Because the distance between the terminal and the base station is different from the distance between the terminal and the RRH, each propagation delay is different. For this reason, when a packet is transmitted from the terminal to the base station and the RRH at the same timing, at least one of the base station and the RRH receives the packet at a timing different from the packet from the other terminal. Therefore, the terminal needs to manage the synchronization timing of a plurality of uplinks in order to transmit packets to the base station and the RRH at different timings.

Note that, as shown in FIGS. 9A to 9D, when the terminal performs carrier aggregation within one network entity, the uplink timing may be different for each component carrier. FIG. 9 (e) shows an example in which a base station and an RRH are provided as different network entities. However, when a base station and a relay node, a relay node and an RRH, or a relay node and a base station are provided, The same is true regardless of the combination.

Hereinafter, the procedure when the terminal that performs carrier aggregation establishes uplink synchronization to the network entity will be described. FIG. 12 is a timing chart illustrating a procedure when a terminal that performs carrier aggregation establishes synchronization of an uplink to a network entity. In the example illustrated in FIG. 12, the terminal establishes uplink synchronization for two TA (Timing Alignment) groups 1 and 2 each including at least one component carrier having the same uplink timing. In order to establish uplink synchronization, transmission timing adjustment (Timing Alignment) is performed by performing a random access procedure (RandomandAccess Procedure) for each TA group.

As illustrated in FIG. 12, for each TA group, the terminal responds to a random access preamble (Random Access Preamble Assignment) transmitted from a network entity that provides a component carrier. Access Preamble: RA Preamble) to the network entity. As a response to the random access preamble, the network entity sends a random access response (Random Access Response: RA Response) including a TA command (Timing Advanced Command) to the identifier “RA-RNTI ( Random Access Radio Network Temporary Identity) ”. Here, since “RA-RNTI” is an identifier corresponding to the timing of the random access preamble, it is an identifier common to a plurality of terminals transmitting at the same timing, and is not an identifier unique to the terminal. The terminal refers to the identifier “RA-RNTI” to determine whether or not the random access response sent from the network entity is a response addressed to itself.
Note that the terminal may send a random access preamble without receiving a random access preamble assignment.

The TA command included in the random access response includes a value for deriving a timing adjustment value based on the downlink reception timing corresponding to the uplink whose timing is synchronized. That is, if the actual timing adjustment value is included in the TA command, the amount of information increases. Therefore, the terminal calculates the actual timing adjustment value using a calculation formula. The calculation formula is held in advance in the terminal. Each parameter constituting the calculation formula is a fixed value and a selection value determined by a system mode (FDD: Frequency ： Division Duplex) or TDD: Time Division Duplex). The terminal inputs the value sent by the TA command into the calculation formula and calculates the actual timing adjustment value. The terminal calculates a new uplink synchronization timing by subtracting the calculated timing adjustment value from the downlink reception timing.

The period of use of the synchronized uplink is counted by a timer called “Time Alignment Timer”. The value counted by the timer is sent from the base station to the terminal. The synchronized uplink is defined to be usable for a period from the time of synchronization to a predetermined time. That is, in principle, uplink synchronization is maintained during the timer count period. However, the uplink synchronization timing changes as the terminal moves. Therefore, in actuality, it is necessary to adjust uplink synchronization timing (Timing Alignment) as the terminal moves.

As described above, when the terminal that performs carrier aggregation needs to manage the synchronization timing of a plurality of uplinks, the terminal performs uplink synchronization timing compared to the case of managing the synchronization timing of one uplink. The frequency of adjustment is high. As described above, when the terminal adjusts the uplink synchronization timing, a random access procedure (Random Access Procedure) is performed between the terminal and the network entity. For this reason, it is desirable that the time required for one procedure is short in order to quickly and efficiently perform processing for the terminal to be able to use the component carrier provided by the network entity.

An object of the present invention is to provide a wireless communication device capable of quickly and efficiently performing processing for adjusting the synchronization timing when a wireless communication terminal performing carrier aggregation manages synchronization timing of a plurality of uplinks, A wireless communication system and a wireless communication terminal are provided.

The present invention is a wireless communication apparatus capable of communicating with a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings, and is in a plurality of component carriers used by the wireless communication terminal When the wireless communication terminal establishes uplink synchronization in a second component carrier associated with the first component carrier in a state where uplink synchronization is established in a reference first component carrier, the wireless communication Provided is a wireless communication device that transmits an individual control signal including an adjustment value of a transmission timing of the wireless communication terminal to the terminal using an identifier unique to the wireless communication terminal.

The present invention is a wireless communication system including a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings, and a wireless communication device that can communicate with the wireless communication terminal. ,
In a state where uplink synchronization is established in a first component carrier serving as a reference among a plurality of component carriers used by the wireless communication terminal, the wireless communication terminal is connected to a second component carrier associated with the first component carrier. When establishing uplink synchronization,
A first wireless communication device that provides a communication cell of the first component carrier and a second wireless communication device that provides a communication cell of the second component carrier are each between the first component carrier and the second component carrier. Transmitting an individual control signal including synchronization timing calculation information indicating a synchronization timing shift on the wireless communication device side to the wireless communication terminal;
The wireless communication terminal uses the time difference of the downlink synchronization timing in each component carrier and the synchronization timing calculation information included in the individual control signal to determine the uplink synchronization timing and the first component carrier in the second component carrier. An uplink timing difference, which is a time difference in uplink synchronization timing in the first component carrier, is calculated, and based on the uplink synchronization timing and the uplink timing difference in the first component carrier, the uplink synchronization timing in the second component carrier A wireless communication system for deriving data is provided.

The present invention is a wireless communication system comprising: a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells; and a wireless communication device that can communicate with the wireless communication terminal, wherein the mobile communication When a terminal is handed over from a first wireless communication apparatus that provides a first component carrier serving as a reference among a plurality of component carriers used by the wireless communication terminal to a second wireless communication apparatus, the first wireless communication apparatus and the The second wireless communication apparatus sets a reference timing common to the first component carrier and a second component carrier of a communication cell provided by the second wireless communication apparatus, and the first wireless communication apparatus includes the first component Information indicating the difference between the transmission / reception timing on the carrier and the reference timing Provided to a second wireless communication device, the second wireless communication device includes synchronization timing calculation information indicating a synchronization timing shift between the first component carrier and the second component carrier on each wireless communication device side The individual control information related to the handover is transmitted to the radio communication terminal via the first radio communication device, and the radio communication terminal transmits the time difference of the downlink synchronization timing in each component carrier and the synchronization included in the individual control signal. Based on the timing calculation information, an uplink timing difference that is a time difference between an uplink synchronization timing in the second component carrier and an uplink synchronization timing in the first component carrier is calculated, and an uplink link in the first component carrier is calculated. Based on the synchronization timing and the uplink timing difference, to provide a wireless communication system for deriving a synchronization timing for the uplink in the second component carrier.

The present invention is a wireless communication apparatus capable of communicating with a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings, and is in a plurality of component carriers used by the wireless communication terminal A control unit that provides a communication cell of a first component carrier serving as a reference or a communication cell of a second component carrier that accompanies the first component carrier, and the wireless communication terminal performs uplink synchronization in the first component carrier. When the wireless communication terminal establishes uplink synchronization with the second component carrier in the established state, synchronization timing on the wireless communication device side between the first component carrier and the second component carrier Synchronous tie indicating misalignment To provide a radio communication apparatus having a transmitting unit that transmits dedicated control signal including a ring calculation information to the wireless communication terminal.

The present invention is a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings, and is a first component carrier that serves as a reference among the plurality of component carriers used by the wireless communication terminal When uplink synchronization is established with a second component carrier associated with the first component carrier in a state in which uplink synchronization is established, a time difference between downlink synchronization timings of each component carrier and the radio Synchronization timing calculation information indicating a difference in synchronization timing on the wireless communication device side between the first component carrier and the second component carrier, which is included in an individual control signal transmitted from a wireless communication device with which a communication terminal can communicate Based on An uplink timing difference calculating unit that calculates an uplink timing difference that is a time difference between an uplink synchronization timing in the second component carrier and an uplink synchronization timing in the first component carrier; and in the first component carrier Provided is a wireless communication terminal comprising: a synchronization timing deriving unit that derives uplink synchronization timing in the second component carrier based on uplink synchronization timing and the uplink timing difference.

The present invention provides a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells, and provides a first component carrier that serves as a reference among the plurality of component carriers used by the wireless communication terminal. When handing over from one radio communication apparatus to the second radio communication apparatus, the time difference between the downlink synchronization timings in each component carrier and the individual control sent from the second radio communication apparatus providing the communication cell of the second component carrier Based on synchronization timing calculation information indicating a shift in synchronization timing between the first component carrier and the second component carrier on each wireless communication device side included in the signal, the uplink component in the second component carrier Synchronization timing and An uplink timing difference calculating unit that calculates an uplink timing difference that is a time difference of uplink synchronization timing in the first component carrier, and based on the uplink synchronization timing and the uplink timing difference in the first component carrier There is provided a wireless communication terminal comprising a synchronization timing deriving unit for deriving uplink synchronization timing in the second component carrier.

According to the wireless communication device, the wireless communication system, and the wireless communication terminal according to the present invention, when the wireless communication terminal that performs carrier aggregation manages the synchronization timing of a plurality of uplinks, the process for adjusting the synchronization timing is performed. It can be done quickly and efficiently.

In the wireless communication system according to the first embodiment, a timing chart when a terminal establishes uplink synchronization for two TA (Timing Alignment) groups 1 and 2 each including at least one component carrier. Block diagram of a terminal constituting the wireless communication system of the first embodiment Block diagram of a network entity constituting the wireless communication system of the first embodiment Timing chart showing a procedure performed between two network entities belonging to different TA groups in the wireless communication system according to the second embodiment. The figure which shows the difference between the reference timing and the transmission / reception timing of the packet of each network entity and the difference between the reference timing and the transmission / reception timing of the terminal Timing chart showing a handover procedure in the wireless communication system of the third embodiment The figure which shows the difference between the reference timing and the packet transmission / reception timing in the PCell of each network entity of the handover source and the handover destination, and the difference between the reference timing and the transmission / reception timing of the terminal (A) And (b) is a figure which shows the example of a carrier aggregation (A)-(e) is a schematic diagram showing a plurality of cells managed by a base station as a network entity The figure which shows the example in case the terminal has a some uplink synchronous timing in the aspect shown in FIG.9 (e). The figure which shows the example in case a terminal uses the component carrier of a some carrier frequency Timing chart showing the procedure for a carrier aggregation terminal to establish uplink synchronization to a network entity

Embodiments of a wireless communication system according to the present invention will be described in detail with reference to the drawings. A wireless communication system according to an embodiment described below includes at least one wireless communication terminal and at least one network entity that can communicate with the wireless communication terminal via a wireless communication network. In the following description, the wireless communication terminal is simply referred to as “terminal”. The terminal is, for example, a mobile phone. The network entity is a radio communication base station (eNB), an RRH (Remote Radio Head) installed in an area away from the radio communication base station, a relay node (relay node) wirelessly connected to the radio communication base station, etc. Or a repeater), a femto base station, and the like, which is a node to which a terminal can connect wirelessly. The RRH has the same function as the radio unit (Radio-Frequency unit: RF unit) of the radio communication base station, and is connected to the control unit of the radio communication base station by a wired cable.

The wireless communication system uses LTE or LTE-A mobile communication technology standardized by 3GPP (The 3rd Generation Generation Partnership Project). However, the mobile communication technology used by the wireless communication system is not limited to the above standards, and WiMAX (Worldwide Interoperability for Microwave Access) such as wireless LAN (Wireless Local Area Network), IEEE802.16, IEEE802.16e, IEEE802.16m, It may be 3GPP2, SAE (System Architecture Evolution), UMTS (Universal Mobile Telecommunications System), or the fourth generation mobile communication standard.

Each network entity constitutes at least one communication cell. A communication cell refers to a radio network object that a terminal can uniquely identify based on an identifier assigned to a geographical area or a difference in frequency used in the geographical area. In the following description, a communication cell is simply referred to as a “cell”. One network entity constitutes one or more cells for each of one or more carrier frequencies. Further, the terminal communicates using at least one communication cell configured by the network entity. The terminal can perform “carrier aggregation” described with reference to FIGS. 8A and 8B and FIGS. 9A to 9E in communication with the network entity. .

Note that the carrier aggregation is composed of a combination of PCell (Primary Serving Cell) and SCell (Secondary Serving Cell). The PCell is a cell necessary for the terminal to maintain the connection with the network, and provides a reference component carrier. The SCell is a cell used by the terminal to increase the capacity of packet transmission / reception with the network or to distribute the packet transmission / reception traffic, and provides a component carrier associated with a reference component carrier.

In the following embodiments, description will be made using PCell and SCell. However, the present invention is not limited to carrier aggregation using one PCell and a plurality of SCells, but carrier aggregation using a plurality of PCells and a plurality of SCells. It can also be applied to. Furthermore, it can be applied to carrier aggregation that does not have the concept of PCell and SCell.

Hereinafter, the wireless communication systems of the first to third embodiments will be described in order. In the first to third embodiments, components having the same function are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
A wireless communication system according to the first embodiment will be described. The wireless communication system according to the first embodiment includes the above-described terminals and network entities. The terminal has a function of receiving a synchronization signal transmitted from the network entity for each cell in the downlink and synchronizing with the uplink of each cell. The network entity also serves as an access point of a radio access network for terminals, and allocates and manages radio resources (for example, frequency bands in the frequency domain or time domain) for each terminal.

FIG. 1 shows a timing when a terminal establishes uplink synchronization for two TA (Timing Alignment) groups 1 and 2 each including at least one component carrier in the wireless communication system of the first embodiment. It is a chart. As shown in FIG. 1, when the terminal has not established uplink synchronization for any TA group, a random access procedure is performed between the TA group 1 including the PCell and the terminal.

In the random access procedure, a terminal uses a random access preamble (RandomandAccess) according to a random access preamble assignment (Random Access Preamble Assignment: RA Preamble Assignment) sent from a network entity that provides component carriers included in TA group 1. Preamble: (RA) Preamble) is sent to the network entity. As a response to the random access preamble, the network entity sends a random access response (Random Access Response: RA Response) including a TA command (Timing Advanced Command) to the identifier “RA-RNTI” corresponding to the resource of the random access preamble sent by the terminal Use to send to the terminal. “RA-RNTI” is an identifier common to a plurality of terminals. The terminal refers to the identifier “RA-RNTI” to determine whether or not the random access response sent from the network entity is a response addressed to itself. In this way, the terminal establishes uplink synchronization with the network entities included in TA group 1 (transmission timing adjustment with TA group 1 (timing Alignment completed)). Note that one of the component carriers included in the TA group 1 is the PCell described above. In the random access procedure, the terminal may send a random access preamble without receiving a random access preamble assignment.

In this embodiment, when uplink synchronization is established with a group including a PCell, uplink synchronization to a network entity in which a terminal provides a component carrier included in the remaining group (TA group 2) is performed. Perform a procedure to establish In the procedure, instead of a random access response, a MACCE (Media Access Control Control Element) using an identifier “C-RNTI (Cell Radio Network Temporary Identity)” indicating a destination specific to a terminal under a specified cell is used. . Similar to the random access response, a TA command including a value for deriving an adjustment value based on the downlink reception timing corresponding to the uplink whose timing is synchronized is added to the MACCE. Note that the terminal can use MACCE because the base station identifies the terminal based on the transmission timing when the terminal transmits the random access preamble using the resource to which the base station has performed the random access preamble assignment. This is because it can. In addition, in order to use MACCE, the terminal needs to be able to transmit ACK and NACK, but uplink synchronization is established with TA group 1 including the PCell component carrier, and the terminal is ACK or NACK. This is because NACK can be sent. However, the terminal needs to set in advance whether the control signal including the TA command is a random access response as in the background art or an individual control signal such as MACCE as in the present embodiment. The setting method may be notified from the network entity to the terminal by 1 bit, or the terminal may determine according to the situation. In this way, when receiving a TA command by MACCE, the terminal does not need to receive a random access response, and “RA-RNTI” is set in the downlink corresponding to the uplink that has transmitted the random access preamble. Since it is not necessary to monitor, the processing load of the terminal is reduced. When not set, the terminal needs to monitor “RA-RNTI” even when a TA command is sent by MACCE.
Here, the “individual control signal” is a control signal for one terminal, and includes, for example, “RRCCeonnection Reconfiguration” in addition to MACCE.

The timing at which the network entity transmits the random access response to the terminal is determined to be after a predetermined time (for example, 6 milliseconds) after the network entity receives the random access preamble. On the other hand, the timing at which the network entity transmits the MACCE to the terminal is arbitrary. Accordingly, the network entity can create a MACCE including a TA command and immediately transmit the MACCE to the terminal. Therefore, the MACCE can send the TA command to the terminal earlier than the random access response. As a result, the terminal can quickly establish uplink synchronization with the TA group 2.

Since the random access response uses an identifier “RA-RNTI” indicating a common destination for a plurality of terminals, a common modulation / coding scheme (MCS) is assigned to the plurality of terminals. . On the other hand, since MACCE uses an identifier “C-RNTI” indicating a destination specific to a terminal under a cell, an MCS suitable for the situation of a specific terminal is assigned. Therefore, efficient transmission is possible by using MACCE as in this embodiment.

Furthermore, when using a random access response, it is necessary to allocate a PDCCH (Physical-Downlink-Control-CHannel (Physical Downlink Control Channel)) in order to transmit data addressed to the terminal. On the other hand, if MACCE is used, data addressed to the terminal can be transmitted together. Thus, resources can be saved by using MACCE.

[Configuration of Terminal of First Embodiment]
FIG. 2 is a block diagram of terminals constituting the wireless communication system according to the first embodiment. As illustrated in FIG. 2, the terminal according to the first embodiment includes a reception unit 101, a control unit 103, and a transmission unit 105.

The receiving unit 101 receives broadcast information, individual control information, random access response, MACCE, or the like via the downlink of the cell being used by the terminal in response to an instruction from the control unit 103. The receiving unit 101 outputs the received broadcast information, individual control information, random access response, MACCE, or the like to the control unit 103.

The control part 103 manages each component carrier of PCell and SCell which comprise a carrier aggregation based on alerting | reporting information, common control information, or individual control information. Therefore, the control unit 103 can know which TA group each component carrier of PCell and SCell belongs to. Note that the TA group to which each component carrier of PCell and SCell belongs may be inferred from the broadcast information, the reception power or reception timing of the cell by the terminal, or may be indicated by the control information sent from the network entity. The control unit 103 outputs information necessary for classifying the PCell and SCell into the TA group (for example, a group number) to the TA control unit 111 included in the control unit 103.

The TA control unit 111 includes a TA management unit 121 and a TA command analysis unit 123. The TA management unit 121 manages the synchronization timing of the PCell and SCell for each TA group. The TA command analysis unit 123 derives a value related to the synchronization timing in each component carrier from the random access response received by the reception unit 101 or the TA command included in the MACCE. The TA command analysis unit 123 sets the derived value related to the synchronization timing in the TA management unit 121 for each TA group.

The transmission unit 105 transmits a random access preamble to a network entity in a predetermined cell in response to an instruction from the control unit 103.

[Configuration of Network Entity of First Embodiment]
FIG. 3 is a block diagram of network entities constituting the wireless communication system of the first embodiment. As illustrated in FIG. 3, the network entity according to the first embodiment includes a reception unit 201, a control unit 203, and a transmission unit 205.

The receiving unit 201 receives a random access preamble or a buffer status report transmitted from the terminal, and outputs it to the control unit 203. In addition, the reception unit 201 outputs information regarding the cell that has transmitted the received random access preamble to the control unit 203.

The control unit 203 manages each component carrier provided by the network entity. The control unit 203 includes a TA management unit 211 and a TA command creation unit 213. The TA management unit 211 manages whether synchronization is established in each component carrier provided by the network entity. The TA command creation unit 213 creates a TA command to be added to the random access response or MACCE that the transmission unit 205 sends to the terminal. The TA command includes a value for adjusting the uplink synchronization timing based on the downlink reception timing corresponding to the uplink to which the terminal has transmitted the random access preamble.

The transmission unit 205 transmits a random access response, MACCE, or the like to a terminal using a predetermined cell in response to an instruction from the control unit 203.

Hereinafter, in the timing chart shown in FIG. 1, an example of a procedure performed to establish uplink synchronization to TA group 2 performed after establishing uplink synchronization to TA group 1 including PCell. Will be described in detail.

(First embodiment)
When a network entity belonging to the TA group 2 uses an uplink to a terminal that does not transmit / receive a packet, the network entity assigns a random access preamble assignment to the terminal via a downlink of a component carrier (SCell) that constitutes carrier aggregation. Send to.

When the receiving unit 101 of the terminal receives the random access preamble assignment, the control unit 103 instructs the transmitting unit 105 to transmit the random access preamble in the uplink of the cell scheduled by the random access preamble assignment. The transmission unit 105 transmits the random access preamble to the network entity that has transmitted the random access preamble assignment according to the scheduling instructed by the control unit 103. At this time, the transmission unit 105 outputs the cell that has transmitted the random access preamble and its transmission timing to the TA command analysis unit 123 of the control unit 103.

When the reception unit 201 of the network entity that has transmitted the random access preamble assignment to the terminal receives the random access preamble, the TA command creation unit 213 of the control unit 203 determines that the random access preamble is in the TA group including the PCell component carrier. It is determined whether the signal is for adjusting the uplink synchronization timing or the signal for adjusting the uplink synchronization timing in the TA group not including the PCell component carrier. Since the present embodiment is the latter case, the TA command creation unit 213 confirms with the TA management unit 211 whether synchronization with the component carrier of the PCell is maintained.

In this embodiment, since synchronization with the PCell component carrier is maintained, the TA command creation unit 213 creates a MACCE including a TA command. The TA command includes a value for adjusting the uplink synchronization timing, and the value is derived from the timing at which the random access preamble is received. The TA command creation unit 213 instructs the transmission unit 205 to transmit the MACCE to the terminal in a cell corresponding to the cell that has received the random access preamble. In this way, even if the MACCE does not include TA group identification information, the terminal can determine which TA group the TA command is for from the received cell.

However, the TA command creation unit 213 may include TA group identification information, that is, information indicating the TA group 2 in the MACCE in this embodiment. In this case, the TA command creation unit 213 does not need to notify the transmission unit 205 of a cell for transmitting MACCE. The TA group identification information is a TA group identifier, a cell identifier belonging to the TA group, or a cell index at the time of cell setting. The transmission unit 205 transmits a MACCE including a TA command to the terminal in accordance with an instruction from the TA command creation unit 213.

When the receiving unit 101 of the terminal receives the MACCE, it outputs the MACCE to the control unit 103. Note that, when outputting the MACCE to the control unit 103, the reception unit 101 may output MACCE reception cell information indicating which cell received the MACCE to the control unit 103. The receiving unit 101 may output a logical channel ID (Logical Channel ID: LCID) for MACCE to the control unit 103. When the TA command is added to the MACCE, the control unit 103 outputs the MACCE to the TA command analysis unit 123. The control unit 103 may output the MACCE received cell information to the TA command analysis unit 123. Further, the control unit 103 may output the LCID for the MACCE to the TA command analysis unit 123.

When TA group identification information is included in the MACCE, the TA command analysis unit 123 recognizes that the TA command included in the MACCE is a command related to the TA group indicated by the TA group identification information. On the other hand, when the TA group identification information is not included in the MACCE, the TA command analysis unit 123 recognizes that the TA command included in the MACCE is a TA command related to the TA group to which the cell receiving the MACCE belongs.

When the TA group indicated by the TA command included in the MACCE matches the TA group to which the cell to which the transmission unit 105 has transmitted the random access preamble belongs, the TA command analysis unit 123 newly synchronizes the TA command included in the MACCE. Is determined to be a TA command (hereinafter referred to as a “new TA command”). On the other hand, when the TA group indicated by the TA command included in the MACCE does not match the TA group to which the cell to which the transmission unit 105 has transmitted the random access preamble does not match, the TA command included in the MACCE is synchronized. Is a TA command (hereinafter referred to as “TA command for updating”). Note that the MACCE LCID may be different depending on whether the MACCE includes an update TA command or a new TA command. In this case, the TA command analysis unit 123 determines whether it is an update TA command or a new TA command based on the LCID for the MACCE.

When the TA command analysis unit 123 determines that the TA command is a new TA command, uplink synchronization in the TA group to which the cell that has transmitted the random access preamble belongs, based on the transmission timing at which the random access preamble is transmitted and the TA command. Derived timing. On the other hand, if the TA command analysis unit 123 determines that the TA command is for update, the TA command analysis unit 123 requests the TA management unit 121 for information regarding the synchronization timing of the corresponding TA group. The TA command analysis unit 123 derives a new synchronization timing based on the current synchronization timing of the corresponding TA group obtained from the TA management unit 121 and the update TA command. The TA command analysis unit 123 sets the derived value related to the new synchronization timing in the TA management unit 121 together with the TA group information.

Note that the TA command analysis unit 123 discards the information on the cell that has transmitted the random access preamble and its transmission timing after a certain period. The certain period is a period during which MACCE for this random access preamble may be received. The value of this period may be derived based on information obtained by the terminal from the network entity, or may be set in the terminal in advance.

(Second embodiment)
In the second embodiment, the operation of the terminal when the terminal fails to receive the MACCE transmitted by the network entity will be described. The control unit 103 of the terminal determines retransmission of the random access preamble if no MACCE is input even after a certain period of time has passed since the random access preamble was transmitted to the network entity. Note that the retransmission scheduling of the random access preamble is defined by random access preamble assignment. The control unit 103 instructs the transmission unit 105 to transmit the random access preamble in the uplink of the cell scheduled by the random access preamble assignment. Other operations are the same as those in the first embodiment.

(Third embodiment)
In the third embodiment, the operation of the network entity when the timing at which the data transmitted from the terminal is received by the network entity is shifted will be described. The control unit 203 of the network entity determines that the uplink timing is not synchronized when the reception timing of the data transmitted from the terminal is shifted by a predetermined time or more from the original timing. At this time, the control unit 203 outputs information indicating the timing deviation and the corresponding TA group to the TA command creation unit 213. The TA command creation unit 213 creates a TA command based on information indicating a timing shift, and creates a MACCE including the TA command. Other operations are the same as those in the first embodiment.

In the present embodiment, the case where the terminal uses the TA group when the terminal uses a plurality of uplink synchronization timings has been described, but the present invention can also be applied in units of cells.

(Second Embodiment)
A wireless communication system according to the second embodiment will be described. Note that the wireless communication system according to the second embodiment includes a terminal and at least two network entities. Each configuration of the terminal and the network entity is the same as the configuration illustrated in FIGS. 2 and 3 described in the first embodiment.

FIG. 4 is a timing chart showing a procedure performed between two network entities belonging to different TA groups in the wireless communication system of the second embodiment. FIG. 4 shows an example in which two network entities are a radio communication base station (eNB) and an RRH (Remote Radio Radio Head) that is connected to the base station via a wired cable and is installed in an area away from the base station. Indicates. The procedure may be closed to one network entity or may be performed between a plurality of network entities. The network entity types and combinations may be any combination. That is, for example, a combination of relay nodes, a combination of relay nodes and RRHs, or a combination of base stations and relay nodes may be used.

The terminal performs carrier aggregation using cells belonging to different TA groups provided by these two network entities. However, since each network entity belongs to a different TA group, the terminal needs to adjust the uplink synchronization timing for each. In addition, when transmitting a packet to a subordinate terminal, each network entity desirably transmits the packet to all terminals at the same timing so as not to interfere with packet transmission to other terminals. In addition, each network entity desirably receives packets from all terminals at the same timing so as not to interfere with reception of packets from other terminals when receiving packets from subordinate terminals. Accordingly, each network entity sets a reference timing (hereinafter referred to as “reference timing”) in synchronization with each other. By setting a common reference timing among network entities, each network entity can calculate a difference between a packet transmission timing and a reference timing, and a difference between a packet reception timing and a reference timing. This reference timing may be a GPS value, a transmission timing of one network entity, an absolute time, a clock timing, or anything that can be understood by the network entity. In addition, the network entity simultaneously sets subframes for calculating the difference between the reference timing and the transmission / reception timing. At this time, the system frame number may be specified together.

FIG. 5 is a diagram showing the difference between the packet transmission / reception timing and the reference timing of each network entity, and the difference between the terminal transmission / reception timing and the reference timing. FIG. 5 shows an example in which the terminal performs carrier aggregation by simultaneously using cells provided by the eNB and the RRH, respectively.

In the example shown in FIG. 5, the difference in transmission / reception timing of the eNB, RRH, and UE with respect to the reference timing is represented by real values of a to f. A positive value is taken on the right side of the reference timing, and a negative value is taken on the left side of the reference timing. The difference between the timing at which the eNB transmits a packet to the terminal (UE) and the reference timing is “f”. Further, the difference between the timing at which the terminal (UE) receives a packet from the eNB and the reference timing is “d”. Further, the difference between the timing at which the eNB receives a packet from the terminal (UE) and the reference timing is “e”. The difference between the timing at which the terminal (UE) transmits a packet to the eNB and the reference timing is “c”. Further, the difference between the timing when the RRH transmits a packet to the terminal (UE) and the reference timing is “h”. Further, the difference between the timing at which the terminal receives a packet from the RRH and the reference timing is “b”. The difference between the timing at which the RRH receives a packet from the terminal (UE) and the reference timing is “g”. Further, the difference between the timing at which the terminal (UE) transmits a packet to the RRH and the reference timing is “a”. Note that the subframes shown in FIG. 5 all have the same subframe number.

Each network entity (eNB and RRH) recognizes the difference between the reference timing and the transmission / reception timing of its own packet. As shown in FIG. 4, each network entity notifies the other network entity of a value indicating the difference between the reference timing and the transmission / reception timing of its own packet. Note that any means may be used as the notification method. For example, notification may be made using OAM (Operation And Maintenance), notification using “X2 interface”, or notification using “S1 interface”.

In the following, relational expressions that can be derived from downlink and uplink timings in each network entity and terminal will be described. The propagation delay between the network entity and the terminal is the same for the uplink and downlink. For this reason, the following formulas (1) and (2) hold. Furthermore, Expression (3) is established from Expression (1) -Expression (2).
ec = df (1)
ga = bh (2)
a−c = (d−b) + (h−f) + (ge) (3)

{Ac} shown on the left side of Equation (3) is equal to the period t2-t1 shown in FIG. Time t1 is a timing at which the terminal (UE) transmits a packet to the eNB, and time t2 is a timing at which the terminal (UE) transmits a packet to the RRH. Therefore, {ac} indicating the period t2-t1 is equal to the time difference between the uplink synchronization timing to the RRH and the uplink synchronization timing to the eNB.

Since the terminal (UE) can grasp the downlink synchronization timing of each network entity, it can calculate the value of {db} shown on the right side of Equation (3). Therefore, if the terminal obtains the value of {(h−f) + (ge)} shown on the right side of Equation (3), the terminal will be represented by {a−c shown on the left side of Equation (3). } Can be calculated. Each network entity holds a value indicating a difference (e, f, g, h) between the reference timing and the packet transmission / reception timing of itself and the other network entity. Therefore, the network entity of this embodiment provides the terminal with a value of {(h−f) + (ge)}. As a result, the terminal can calculate a time difference in uplink synchronization timing between network entities. The downlink reference cell used to derive the uplink synchronization timing may be any cell in the TA group to which the uplink belongs. In addition, the reference cell may be notified from the base station to the terminal in advance, or may be set in advance in the terminal.

The timing at which the network entity provides the value of {(hf) + (ge)} to the terminal is that the terminal performing carrier aggregation in a state where uplink synchronization with respect to one network entity has already been established. It is time to perform processing to establish uplink synchronization for the other network entity. Therefore, the network entity only needs to calculate the value of {(h−f) + (ge)} before transmitting the MACCE to the terminal.

When the present embodiment is applied to FIG. 1, a value that can calculate the value of {(h−f) + (ge)} by the MACCE transmitted from the TA group 2 is provided to the terminal. However, in the present embodiment, it is not necessary to transmit / receive a random access preamble assignment and a random access preamble response between the terminal and the TA group 2 before transmitting the MACCE. In addition, MACCE can transmit any cell as long as the cell is monitoring the downlink by including information indicating which TA group the uplink adjustment is for in MACCE. The uplink adjustment for which TA group may be a cell identifier, a TA group identifier, or a cell index at the time of cell setting.

MACCE includes a TA command including a value capable of calculating a value of {(h−f) + (ge)}. The terminal calculates {a−c} from Expression (3) based on the value of {(h−f) + (ge)} and the downlink synchronization timing of each network entity. Further, the terminal derives the uplink synchronization timing for the other network entity by adding the value of {ac} to the uplink synchronization timing for the one network entity already established.

In FIG. 4, values indicating the difference between the reference timing and the transmission / reception timing of its own packet are mutually notified between the network entities (eNB and RRH), but {(h−f) + (g− e)} to the network entity that notifies the value that can be calculated, the other network entity only needs to notify the value indicating the difference between the reference timing and the transmission / reception timing of its own packet. That is, the network entity that notifies the terminal of a value that can calculate the value of {(h−f) + (ge)} indicates a value indicating the difference between the reference timing and the transmission / reception timing of its own packet. There is no need to notify the entity.

As described above, according to the present embodiment, the uplink synchronization timing for the other network entity is established in the state in which the terminal performing carrier aggregation has already established the uplink synchronization for the one network entity. , The terminal can obtain a value of {(h−f) + (ge)}. Since the terminal can adjust the synchronization timing of other uplinks based on the synchronization timing of uplinks that are already synchronized, it is called “Time Alignment Timer” that counts the usage period of the other uplinks There is no need to provide a timer. Therefore, the hardware configuration of the terminal can be simplified. Further, since the terminal does not need to monitor the random access preamble assignment, it is possible to reduce the power consumption and simplify the hardware configuration.

Note that when the terminal holds a calculation formula for calculating the value of {(h−f) + (ge)} and the network entity does not perform calculation using the calculation formula, the network entity A value of a difference (e, f, g, h) between the timing and the packet transmission / reception timing of the network entity itself and the other network entity is provided to the terminal.

Further, the value that can be calculated as {(h−f) + (ge)} provided to the terminal by the network entity is {(h−f) + (ge)} in units of [μ seconds]. May be an absolute value represented by.

Further, the value that can calculate the value of {(h−f) + (ge)} provided to the terminal by the network entity is the formula for calculating {(h−f) + (ge)}. In advance, the terminal can be adjusted with a small number of bits. Non-Patent Document 3 discloses a method of notifying by {actual value = (notifying value × 16) × Ts}. Note that Non-Patent Document 4 defines Ts = 1 / (30720) [msec]. This method can be applied.

However, there are cases where the number of bits increases because the difference between network entities is larger than in the past. Therefore, the value may be expressed by a narrow interval for a small value and a wide interval for a large value. The value may be expressed in increments of 0.5 milliseconds, for example. At this time, the value is represented by 3 bits, the first bit indicates the sign (+ or-) of the value, and the second to third bits are 0 ms, 0.5 ms, 1.0 ms, and 1.5 ms. Indicates one of the following. Note that a fine value of 0 to 0.5 milliseconds may be indicated by the fourth and subsequent bits.

In addition, the value of {(h−f) + (ge)} provided to the terminal by the network entity is the same as the difference in the subframe number with respect to the synchronization timing of the uplink that has already been synchronized. You may be comprised by the shift | offset | difference of the timing by a sub-frame number. In this way, the number of bits to be sent can be reduced. At this time, a difference in system frame numbers may also be notified.

Moreover, although this embodiment demonstrated based on the example which a different network entity, such as eNB and RRH, each provided with the several cell which a terminal uses for a carrier aggregation, the said several cell is provided by the same network entity. May be.

In this embodiment, a value that can calculate the value of {(h−f) + (ge)} is included in the TA command of MACCE and provided to the terminal, but the random access response in the random access procedure is provided. May be included in the TA command included in the command. Further, when there are a plurality of terminals whose synchronization timing can be adjusted based on the value of {(hf) + (ge)}, the network entity may provide the value to all of the plurality of terminals. .

In the present embodiment, the case where two TA groups are used has been described as an example, but any number of TA groups can be applied. That is, the present embodiment may be applied to a TA group serving as a reference for each TA group (for example, a TA group to which a PCell belongs).

This embodiment can also be applied when the synchronization timing is readjusted because the synchronization timing has shifted in the cells constituting the carrier aggregation.

Further, in the present embodiment, the method of sending a TA command using MACCE is exemplified, but instead of using MACCE, when setting a cell, {(h−f) + (ge) for each TA group. } May be included. For example, it may be included in the “RRCCeonnectionReconfiguration message”. For example, it may be included in the “RRCConnectionSetup message”. By doing so, the terminal derives the uplink synchronization timing of another TA group without performing a random access procedure after the uplink synchronization timing of a cell (for example, PCell) serving as a reference for carrier aggregation is established. it can. For a TA group that maintains uplink synchronization timing of a reference cell (for example, a TA group to which a PCell belongs), a value that can calculate a value of {(hf) + (ge)} is included. It does not have to be. In addition, when a value capable of calculating the value of {(h−f) + (ge)} is included for each TA group, only {(h− A value that can calculate the value of f) + (ge)} may be notified.

By doing so, the terminal maintains uplink synchronization based on the uplink synchronization timing of the reference TA group (for example, the TA group to which the PCell belongs) only by sending it once when setting the cell. be able to. In addition, when changing the timing on the network side, the timing can be easily adjusted by notifying the terminal of the reset value. Therefore, timing update signaling can be reduced and radio resources can be used effectively. Also, since a random access procedure is not used, the hardware configuration becomes easy. In addition, since the random access response is not monitored, the hardware configuration is facilitated and the power consumption can be reduced.

Also, in this embodiment, between the network entity that manages the TA group used as a reference by the terminal and the network entity that adjusts the uplink timing, each network entity determines the difference between the reference timing and the transmission / reception timing of its own packet. Although the method of notifying the other network entity of the indicated value has been shown, the transmission / reception timing difference may be calculated via another network entity or using information held by the other network entity.

Also, the network entity that notifies the terminal of a value that can calculate the value of {(h−f) + (ge)} may be a network entity that provides a cell in which the terminal is monitoring the downlink.

Also, in this embodiment, between the network entity that manages the TA group used as a reference by the terminal and the network entity that adjusts the uplink timing, each network entity determines the difference between the reference timing and the transmission / reception timing of its own packet. The method of notifying the other network entity of the indicated value has been shown. However, for the network entity that transmits a value capable of calculating the value of {(h−f) + (ge)} to the terminal, {(h− A value capable of calculating the value of f) + (ge)} may be transmitted. Also, the difference between the reference timing and the packet transmission / reception timing of the network entity itself and the other network entity (for the network entity that transmits a value capable of calculating the value of {(h−f) + (ge)} to the terminal ( The values of e, f, g, h) may be transmitted. Also, the value of {(hf) + (ge)} can be calculated for a network entity that transmits a value capable of calculating the value of {(h−f) + (ge)} to the terminal. An individual control signal including a value may be transmitted.

Using the method of the present embodiment, the uplink synchronization timing may be updated only for the reference TA group (for example, the TA group to which the PCell belongs). For other TA groups, when the downlink synchronization timing is shifted or when the uplink synchronization timing is updated in the reference TA group, the uplink synchronization timing is recalculated and updated in the same manner. To do. By doing so, it is not necessary to send information for updating the uplink synchronization timing for each TA group, so that radio resources can be used effectively. Further, since the MACCE for updating the synchronization timing is not used for each TA group, it is not necessary to expand the MACCE.

Further, in the present embodiment, a method of synchronizing between different network entities and exchanging transmission / reception timing for each network entity has been described. However, when a cell managed by a base station is extended by a repeater (booster) or the like, a terminal The transmission / reception timing is determined by the transmission / reception timing of the base station. In this case, the uplink synchronization timing for the cell of the terminal is derived based on the transmission / reception timing of the cell at the base station. That is, the present invention can be applied by deriving {(h−f) + (ge)} using the transmission / reception timing of the cell at the base station.

When the transmission timing of the reference TA group (for example, the TA group to which the PCell belongs) is used as the reference timing, {h + (ge) instead of {(h−f) + (ge)} } Is used. However, the terminal does not need to know this. When the values of h, g, and e are independently notified to the terminal, it is possible to operate correctly if it is determined that the terminal is not included in the terminal.

(Third embodiment)
A wireless communication system according to the third embodiment will be described. The wireless communication system according to the third embodiment includes a terminal and at least two network entities. Each configuration of the terminal and the network entity is the same as the configuration illustrated in FIGS. 2 and 3 described in the first embodiment. Note that the third embodiment is an embodiment in which the procedure described in the second embodiment is applied to a handover procedure. Although this embodiment demonstrates the case where the terminal is performing the carrier aggregation, it is applicable also when not performing the carrier aggregation.

FIG. 6 is a timing chart showing a handover procedure in the wireless communication system of the third embodiment. FIG. 6 shows a case where the terminal (UE) is connected to the source eNB and is handed over from the source eNB to the target eNB as the terminal moves. As described above, FIG. 6 shows an example in which handover is performed to different network entities, but the present embodiment is also applicable to handover within the same network entity.

As shown in FIG. 6, the source eNB and the target eNB set a reference timing (hereinafter referred to as “reference timing”) in synchronization with each other. This reference timing may be a GPS value, a transmission timing of one network entity, an absolute time, a clock timing, or anything that can be understood by the network entity. In addition, the network entity simultaneously sets subframes for calculating the difference between the reference timing and the transmission / reception timing. At this time, the system frame number may be specified together.

Next, the source eNB receives a value indicating a difference “F” between the reference timing and the timing at which the source eNB transmits a packet to the terminal (UE), and the reference timing and the source eNB receives the packet from the terminal (UE). The target eNB is notified of a value indicating a difference “E” from the timing to perform. Note that since the terminal is performing carrier aggregation, the source eNB notifies the target eNB of values indicating timing differences in the PCell.

FIG. 7 is a diagram showing the difference between the reference timing and the packet transmission / reception timing in the PCell of each handover source and handover destination network entity, and the difference between the reference timing and the terminal transmission / reception timing. In FIG. 7, the handover source network entity is the source eNB, and the handover destination network entity is the target eNB.

In the example shown in FIG. 7, the transmission / reception timing differences of the source eNB, the target eNB, and the terminal (UE) with respect to the reference timing are represented by real values A to F. A positive value is taken on the right side of the reference timing, and a negative value is taken on the left side of the reference timing. The difference between the timing at which the source eNB transmits a packet to the terminal (UE) and the reference timing is “F”. Further, the difference between the timing at which the terminal (UE) receives a packet from the source eNB and the reference timing is “D”. Further, the difference between the timing at which the source eNB receives a packet from the terminal (UE) and the reference timing is “E”. Further, the difference between the timing at which the terminal (UE) transmits a packet to the source eNB and the reference timing is “C”. Further, the difference between the timing at which the target eNB transmits a packet to the terminal (UE) and the reference timing is “H”. Further, the difference between the timing at which the terminal receives a packet from the target eNB and the reference timing is “B”. Further, the difference between the timing at which the target eNB receives a packet from the terminal (UE) and the reference timing is “G”. Further, the difference between the timing at which the terminal (UE) transmits a packet to the target eNB and the reference timing is “A”. Note that the subframes shown in FIG. 7 all have the same subframe number.

The propagation delay between the network entity (source eNB and target eNB) and the terminal (UE) is the same in uplink and downlink. For this reason, the following formulas (4) and (5) hold. Furthermore, Expression (6) is established from Expression (4) -Expression (5).
EC = DF (4)
GA = BH (5)
A−C = (D−B) + (HF) + (GE) (6)

{AC} shown on the left side of Equation (6) is equal to the period T2-T1 shown in FIG. Time T1 is a timing at which the terminal (UE) transmits a packet to the source eNB, and time T2 is a timing at which the terminal (UE) transmits a packet to the target eNB. Therefore, {AC} indicating the period T2-T1 is equal to the time difference between the uplink synchronization timing to the target eNB and the uplink synchronization timing to the source eNB in the PCell.

When the source eNB decides to hand over the terminal (UE) to the target eNB, the source eNB transmits “Handover Preparation” to the target eNB. The target eNB that has received the “Handover Preparation” sends the “Handover Command” including the value of {(HF) + (GE)} and the uplink usage permission (UL grant) of the target eNB to the source eNB Send to. The source eNB transfers the received “Handover Command” to the terminal (UE) to be handed over.

Since the terminal (UE) can grasp the timing (each downlink synchronization timing in the PCell of the source eNB and the target eNB) of receiving each packet in the PCell from the source eNB and the target eNB, it is shown on the right side of the equation (6) The value of {D−B} can be calculated. Therefore, if the terminal obtains the value of {(HF) + (GE)} shown on the right side of Equation (6), the terminal will be represented by {A−C shown on the left side of Equation (6). } Can be calculated.

The terminal (UE) that has received the “Handover Command” synchronizes the value of {(HF) + (GE)} included in the “Handover Command” with each downlink in the PCell of the source eNB and the target eNB. Based on the timing, {AC} is calculated from Equation (6). Further, the terminal derives the uplink synchronization timing of the TA group including the PCell of the target eNB by adding the value of {A−C} to the uplink synchronization timing of the TA group including the PCell of the source eNB. .

Similarly, the target eNB calculates {(HF) + (GE)} from the transmission / reception timing of the PCell before handover and the transmission / reception timing for each TA group of the SCell for the SCell after handover. Then, the “Handover」 Command ”may be notified to the terminal by including the value of {(HF) + (GE)} for each TA group. The terminal derives the uplink synchronization timing for each TA group of the SCell from the downlink and uplink synchronization timings of the PCell and the value of {(HF) + (GE)} before the handover.

For the SCell after the handover, the target eNB calculates (HF) + (GE)} from the PCell transmission / reception timing after the handover and the transmission / reception timing for each TA group of the SCell. “Command” may include the value of {(HF) + (GE)} for each TA group and notify the terminal. The terminal derives the uplink synchronization timing for each TA group of the SCell from each downlink and uplink synchronization timing of the PCell after handover and the value of {(HF) + (GE)}. Thus, since the uplink synchronization of PCell and SCell can be performed without using a random access procedure at the time of a handover, it can be performed quickly.

In this way, when the timing of the PCell of the target eNB is updated, or when the downlink timing of the PCell and the downlink timing of the SCell are shifted, the uplink of the SCell is not transmitted without timing update signaling. The synchronization timing can be updated. The downlink reference cell used for deriving the uplink synchronization timing of the PCell and SCell may be any cell in the TA group to which the uplink belongs. In addition, the reference cell may be notified from the base station to the terminal in advance, or may be set in advance in the terminal.

Finally, the terminal sends “Handover complete” to the target eNB based on the uplink use permission (UL grant) of the target eNB included in the “Handover Command”.

Thus, the relationship shown in the equation (6) is also established at the time of handover. Therefore, when the handover procedure is performed, the terminal uses the synchronization timing of the uplink of the PCell of the source eNB and the synchronization timing of the uplink of the PCell of the target eNB according to a value derived based on the information sent from the source eNB. Can be determined.

Note that if the terminal holds a calculation formula for calculating the value of {(HF) + (GE)} and the source eNB does not perform calculation using the calculation formula, the target eNB A value of a difference (E, F, G, H) between the timing and the packet transmission / reception timing of itself and the target eNB is provided to the terminal.

In this embodiment, “Handover Command” includes the value {(HF) + (GE)}, but the value {(HF) + (GE)} Only in the case of 0, the terminal may calculate the synchronization timing of the uplink PCell of the target eNB from the synchronization timing of the uplink PCell of the source eNB. In this case, it is represented by 1 bit in “Handover Command”, and the “Handover Command” instructs the terminal to calculate the synchronization timing of the PCell uplink of the target eNB from the synchronization timing of the PCell of the source eNB. May be. In addition, by not including the random access preamble assignment that is conventionally included in “Handover Command”, it is instructed to calculate the synchronization timing of the target eNB PCell uplink from the synchronization timing of the PCell uplink of the source eNB You may do it. In this case, the random access preamble may not be used as long as the uplink synchronization timing of the target eNB PCell can be derived from the synchronization timing of the PCell uplink of the source eNB. For this reason, a terminal can synchronize with a target eNB early. In addition, radio resources can be used efficiently.

In the present embodiment, the case where the terminal uses the TA group when the terminal uses a plurality of uplink synchronization timings has been described, but the present invention can also be applied in units of cells. Further, although the case has been described with the present embodiment where a terminal uses a plurality of uplink synchronization timings, the present embodiment is also applicable to a case where there is only one uplink synchronization timing.

In each of the above embodiments, the base station may have a function of notifying which method is used to synchronize the uplink to the terminal. Further, the terminal may have a function of determining which method is used to synchronize the uplink according to the notification from the base station. Note that the terminal may determine a method for automatically synchronizing the uplink from the received information.

In each of the above embodiments, the case where the present invention is configured by hardware has been described as an example, but the present invention can also be realized by software.

Further, each functional block used in the description of each of the above embodiments is typically realized as an LSI that is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them. Although referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of progress in semiconductor technology or other derived technology, it is naturally possible to integrate functional blocks using this technology. Biotechnology can be applied.

Note that the antenna shown in FIGS. 2 and 3 may be an antenna port. An antenna port refers to a logical antenna composed of one or a plurality of physical antennas. That is, the antenna port does not necessarily indicate one physical antenna, but may indicate an array antenna or the like composed of a plurality of antennas. For example, in LTE (Long Term Evolution), it is not defined how many physical antennas an antenna port is composed of, but is defined as a minimum unit in which a base station can transmit a different reference signal (Reference signal). An antenna port may be defined as a minimum unit for multiplying a weight of a precoding vector.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

This application is based on a Japanese patent application filed on September 30, 2010 (Japanese Patent Application No. 2010-222764), the contents of which are incorporated herein by reference.

The wireless communication apparatus and the wireless communication terminal according to the present invention are useful as a network entity, a wireless communication terminal, and the like that can communicate by using each component carrier of a plurality of communication cells simultaneously by carrier aggregation.

DESCRIPTION OF SYMBOLS 101 Reception part 103 Control part 105 Transmission part 111 TA control part 121 TA management part 123 TA command analysis part 201 Reception part 203 Control part 205 Transmission part 211 TA management part 213 TA command creation part

Claims

A wireless communication device capable of communicating with a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings,
In a state where uplink synchronization is established in a first component carrier serving as a reference among a plurality of component carriers used by the wireless communication terminal, the wireless communication terminal is connected to a second component carrier associated with the first component carrier. When establishing uplink synchronization, the wireless communication terminal transmits an individual control signal including an adjustment value of a transmission timing of the wireless communication terminal using an identifier unique to the wireless communication terminal. Communication device.
The wireless communication device according to claim 1,
The component carriers of the plurality of communication cells are grouped for each component carrier operated at the same synchronization timing, and processing for establishing uplink synchronization in the component carrier is performed in units of groups. Wireless communication device.
The wireless communication device according to claim 1 or 2,
The wireless communication apparatus, wherein the individual control signal is a MACCE (Media Access Control Control Element).
A wireless communication device according to any one of claims 1 to 3,
The wireless communication apparatus that transmits the individual control signal to the wireless communication terminal is a wireless communication apparatus that provides a communication cell of the second component carrier.
A wireless communication system including a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings, and a wireless communication device that can communicate with the wireless communication terminal,
In a state where uplink synchronization is established in a first component carrier serving as a reference among a plurality of component carriers used by the wireless communication terminal, the wireless communication terminal is connected to a second component carrier associated with the first component carrier. When establishing uplink synchronization,
A first wireless communication device that provides a communication cell of the first component carrier and a second wireless communication device that provides a communication cell of the second component carrier are each between the first component carrier and the second component carrier. Transmitting an individual control signal including synchronization timing calculation information indicating a synchronization timing shift on the wireless communication device side to the wireless communication terminal;
The wireless communication terminal uses the time difference of the downlink synchronization timing in each component carrier and the synchronization timing calculation information included in the individual control signal to determine the uplink synchronization timing and the first component carrier in the second component carrier. An uplink timing difference, which is a time difference in uplink synchronization timing in the first component carrier, is calculated, and based on the uplink synchronization timing and the uplink timing difference in the first component carrier, the uplink synchronization timing in the second component carrier A wireless communication system characterized by deriving.
The wireless communication system according to claim 5,
The first wireless communication apparatus that provides the communication cell of the first component carrier and the second wireless communication apparatus that provides the communication cell of the second component carrier are common to the first component carrier and the second component carrier. Set the timing,
The synchronization timing calculation information is
Wireless communication calculated by a wireless communication device capable of communicating with the wireless communication terminal based on information indicating a difference between transmission / reception timing and the reference timing in the first component carrier and the second component carrier system.
The wireless communication system according to claim 5,
The wireless communication apparatus capable of communicating with the wireless communication terminal is a wireless communication apparatus capable of communicating with the first wireless communication apparatus, the second wireless communication apparatus, or another wireless communication terminal.
The wireless communication system according to claim 6,
The second wireless communication apparatus provides the first wireless communication apparatus with information indicating a difference between transmission / reception timing and the reference timing in the second component carrier.
The wireless communication system according to claim 6,
The first wireless communication apparatus provides the second wireless communication apparatus with information indicating a difference between a transmission / reception timing in the first component carrier and the reference timing.
The wireless communication system according to claim 7,
The first wireless communication device or the second wireless communication device is connected to a wireless communication device with which the other wireless communication terminal can communicate with each wireless communication device between the first component carrier and the second component carrier. A wireless communication system, characterized in that it provides synchronization timing calculation information indicating a difference in synchronization timing.
The wireless communication system according to claim 5,
The second wireless communication apparatus transmits the individual control signal to the wireless communication terminal using an identifier unique to the wireless communication terminal.
A wireless communication system comprising: a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells; and a wireless communication device that can communicate with the wireless communication terminal,
When the mobile communication terminal is handed over from a first wireless communication apparatus that provides a first component carrier serving as a reference among a plurality of component carriers used by the wireless communication terminal to a second wireless communication apparatus that is another entity,
The first wireless communication device and the second wireless communication device set a reference timing common to a second component carrier of a communication cell provided by the first component carrier and the second wireless communication device,
The first wireless communication device provides the second wireless communication device with information indicating a difference between transmission / reception timing and the reference timing in the first component carrier,
The second radio communication device receives individual control information related to handover including synchronization timing calculation information indicating a synchronization timing shift between the first component carrier and the second component carrier on each radio communication device side. 1 to the wireless communication terminal via the wireless communication device,
The wireless communication terminal uses the time difference of the downlink synchronization timing in each component carrier and the synchronization timing calculation information included in the individual control signal to determine the uplink synchronization timing and the first component carrier in the second component carrier. An uplink timing difference, which is a time difference in uplink synchronization timing in the first component carrier, is calculated, and based on the uplink synchronization timing and the uplink timing difference in the first component carrier, the uplink synchronization timing in the second component carrier A wireless communication system characterized by deriving.
The wireless communication system according to claim 12,
The second wireless communication apparatus, for each component carrier operated at the same synchronization timing based on transmission / reception timing in the first component carrier, with respect to a third component carrier associated with the second component carrier, Transmitting the individual control information including the synchronization timing calculation information to the wireless communication terminal via the first wireless communication device;
The wireless communication system, wherein the wireless communication terminal derives an uplink synchronization timing in the third component carrier based on an uplink and downlink synchronization timing of the first component carrier.
The wireless communication system according to claim 12,
The second wireless communication apparatus, for each component carrier operated at the same synchronization timing based on transmission / reception timing in the second component carrier, for the third component carrier associated with the second component carrier, Transmitting the individual control information including synchronization timing calculation information to the wireless communication terminal via the first wireless communication device;
The wireless communication system, wherein the wireless communication terminal derives an uplink synchronization timing in the third component carrier based on an uplink and downlink synchronization timing of the second component carrier.
The wireless communication system according to any one of claims 5 to 14,
The synchronization timing shift indicated by the synchronization timing calculation information is:
Inter-carrier transmission timing difference indicating a time difference between transmission timings in the second component carrier and the first component carrier, and inter-carrier reception timing difference indicating a time difference between reception timings in the second component carrier and the first component carrier. And a wireless communication system characterized by the above.
The wireless communication system according to claim 15, wherein
The transmission timing difference between the carriers is a transmission timing difference between each component carrier and the reference timing,
The inter-carrier reception timing difference is a difference in reception timing between each component carrier and the reference timing.
A wireless communication device capable of communicating with a wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings,
A control unit for providing a communication cell of a first component carrier serving as a reference among a plurality of component carriers used by the wireless communication terminal, or a communication cell of a second component carrier associated with the first component carrier;
When the wireless communication terminal establishes uplink synchronization in the first component carrier and the wireless communication terminal establishes uplink synchronization in the second component carrier,
A transmission unit for transmitting an individual control signal including synchronization timing calculation information indicating a synchronization timing shift between the first component carrier and the second component carrier on the wireless communication device side to the wireless communication terminal;
A wireless communication apparatus.
A wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells having different synchronization timings,
Uplink synchronization is established in a second component carrier associated with the first component carrier in a state where uplink synchronization is established in a first component carrier that is a reference among a plurality of component carriers used by the wireless communication terminal. When establishing
Radio between the first component carrier and the second component carrier included in the time difference of the downlink synchronization timing in each component carrier and the individual control signal sent from the radio communication device with which the radio communication terminal can communicate Based on synchronization timing calculation information indicating a synchronization timing shift on the communication device side, uplink timing that is a time difference between uplink synchronization timing in the second component carrier and uplink synchronization timing in the first component carrier An uplink timing difference calculator for calculating the difference;
A synchronization timing deriving unit for deriving an uplink synchronization timing in the second component carrier based on an uplink synchronization timing in the first component carrier and the uplink timing difference;
A wireless communication terminal comprising:
The wireless communication terminal according to claim 18, wherein
The wireless communication device with which the wireless communication terminal can communicate is a wireless communication device that provides a communication cell of the first component carrier, a wireless communication device that provides a communication cell of the second component carrier, or other wireless communication terminal. A wireless communication terminal, which is a communicable wireless communication device.
A wireless communication terminal that performs carrier aggregation using each component carrier of a plurality of communication cells,
When handing over from a first wireless communication apparatus that provides a first component carrier serving as a reference among a plurality of component carriers used by the wireless communication terminal to a second wireless communication apparatus that is another entity,
The first component carrier and the second component included in the time difference of the downlink synchronization timing in each component carrier and the individual control signal sent from the second wireless communication apparatus providing the communication cell of the second component carrier On the basis of synchronization timing calculation information indicating a synchronization timing shift between the carriers on each wireless communication device side, the uplink synchronization timing of the second component carrier and the uplink synchronization timing of the first component carrier An uplink timing difference calculation unit for calculating an uplink timing difference which is a time difference;
A synchronization timing deriving unit for deriving an uplink synchronization timing in the second component carrier based on an uplink synchronization timing in the first component carrier and the uplink timing difference;
A wireless communication terminal comprising:
A wireless communication terminal according to any one of claims 18 to 20, comprising:
The synchronization timing shift indicated by the synchronization timing calculation information is:
Inter-carrier transmission timing difference indicating a time difference between transmission timings in the second component carrier and the first component carrier, and inter-carrier reception timing difference indicating a time difference between reception timings in the second component carrier and the first component carrier. A wireless communication terminal characterized by the sum of
The wireless communication terminal according to claim 21, wherein
The inter-carrier transmission timing difference is a difference between a transmission timing in each component carrier and a reference timing common to the first component carrier and the second component carrier,
The inter-carrier reception timing difference is a difference between a reception timing in each component carrier and the reference timing.