JP2012009945A - Radio communication system, base station device and communication method - Google Patents

Abstract

When a mobile station apparatus is wirelessly connected to a base station apparatus using cells of a plurality of frequency bands, a radio that efficiently makes an activation request to an inactive cell of an adjacent base station apparatus To provide a communication system, a base station apparatus, and a communication method.
A communication system comprising a plurality of base station devices and a mobile station device, wherein the mobile station device communicates by connecting to the base station device using cells of a plurality of frequency bands simultaneously, The plurality of base station apparatuses include a first base station apparatus and a second base station apparatus, and the first base station apparatus includes a message including specific cell information for the second base station apparatus. And the second base station device identifies a combination of cells that can communicate simultaneously with the mobile station device including the specific cell, and all or a part of the specified combination of cells. Activate.
[Selection] Figure 3

Description

  The present invention relates to a radio communication system, a base station apparatus, and a communication method, and more particularly to power saving of a base station apparatus.

  Evolved which realized high-speed communication by adopting OFDM (Orthogonal Frequency-Division Multiplexing) communication method and flexible scheduling of predetermined frequency and time unit called resource block in 3GPP (3rd Generation Partnership Project) which is a standardization project Universal Terrestrial Radio Access (hereinafter referred to as EUTRA) has been studied, and further development of Advanced EUTRA (also referred to as LTE-Advanced) is being promoted.

  In Advanced EUTRA, Carrier Aggregation has been proposed as a technology capable of higher-speed data transmission while maintaining compatibility with EUTRA. Carrier aggregation is a method in which data of a transmitting device transmitted in a plurality of different frequency bands (also referred to as carrier frequency and component carrier) is received by receiving devices corresponding to different frequency bands, respectively. It is a technology that improves the rate. In the following description, a receiving apparatus in downlink transmission is referred to as a mobile station apparatus, a transmitting apparatus in downlink transmission is referred to as a base station apparatus, and a receiving apparatus in uplink transmission is referred to as a base station apparatus or uplink transmission. Although the transmitting apparatus is described as a mobile station apparatus, the application range of the present invention is not limited to these apparatuses.

  Since an advanced EUTRA mobile station apparatus (hereinafter referred to as a mobile station apparatus) needs to receive and measure a plurality of component carriers, the mobile station apparatus may include a wider range of receiving devices or receiving devices than EUTRA. is assumed. For example, although the maximum frequency bandwidth applied to EUTRA is 20 MHz, in Advanced EUTRA, the frequency bandwidth is expanded to a maximum of 100 MHz by carrier aggregation.

  A mobile station apparatus that uses the frequency bandwidth expanded by carrier aggregation as described above in a certain cell reports the reception quality measurement result of the adjacent cell in each frequency band to the cell, thereby Even when moving (handing over) while maintaining communication to a cell in a certain area, it is possible to continue efficient carrier aggregation by combining high quality cells in the handover destination cell.

  In addition, in EUTRA and Advanced EUTRA, a cell of a base station apparatus or a relay station apparatus (a base station apparatus using a wireless connection with another base station apparatus instead of a wired connection to the core network) for power saving and interference mitigation It has been proposed to have a state in which part or all of the wireless transmission is stopped (Non-Patent Document 1). This is a technique that is particularly useful for a cell having a small cell radius included in a macro cell having a large cell radius.

  Stopping radio transmission has a large effect on the mobile station apparatus and other neighboring cells. Therefore, as a specific process for reducing the influence, a cell scheduled to stop radio transmission automatically When handing over the mobile station device of the cell, the handover request message is notified that the own cell is in a stopped state, and then when the own cell is stopped, the own cell is wireless as cell configuration information. A mechanism for notifying neighboring cells including an inactive state (deactivation state) in which transmission / reception is stopped is specified (Non-Patent Document 2).

  In addition, an adjacent cell transmits a signal (referred to as an activation request signal or a WakeUp signal) requesting to enter an active state (activation state) for performing wireless transmission / reception with respect to an inactive state cell, and a power saving state is established. Proposals for performing control have also been made (Non-Patent Document 1). The notification and request messages are usually exchanged between base station apparatuses that control the target cell.

Ericsson, Samsung, Orange, NTT DOCOMO, Vodafone Group, Huawei, Deutsche Telekom, TNO, "LTE energy saving solution proposal following discussions at RAN3 # 66bis", R3-101046,3GPP TSG-RAN WG3 Meeting # 67, San Francisco, USA , 22-26th February 2010 Ericsson, Samsung, Orange, NTT DOCOMO, Huawei, Vodafone Group, Deutsche Telekom, TNO, “RNL-based energy saving solution”, R3-1013G, 3PP. 2010

  In order to reduce the power consumption of the base station and reduce the interference as described above, when the wireless transmission / reception of a part of the plurality of component carriers (cells) used in the carrier aggregation is stopped, the cell adjacent to the inactive cell A mobile station apparatus that is performing carrier aggregation cannot perform quality measurement of an inactive cell and cannot continue carrier aggregation. For this reason, it is necessary to activate cells in an inactive state in advance so that quality measurement can be performed. However, if a combination of cells that can be carrier-aggregated is not known, it is necessary to activate all adjacent inactive cells. However, there are problems of reduction in power saving effect and increase in interference due to activation of many cells.

  In view of the above problems, an object of the present invention is to provide a radio communication system, a base station apparatus, and a communication method capable of efficiently controlling an inactive cell while suppressing a network load.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the communication system of the present invention includes a plurality of base station apparatuses and mobile station apparatuses, and the mobile station apparatus uses the cells of a plurality of frequency bands to simultaneously connect to the base station apparatus to perform communication. The plurality of base station devices includes a first base station device and a second base station device, and the first base station device is specific to the second base station device. A message including cell information is transmitted, and the second base station device identifies combinations of cells that can communicate simultaneously with the mobile station device including the specific cell, and all of the identified combinations Alternatively, some cells are activated.

  (2) In the communication system of the present invention, the specific cell information transmitted from the first base station apparatus is transmitted from the mobile station apparatus that is communicating in a cell under the control of the first base station apparatus. It is selected based on the measurement result.

  (3) Further, in the communication system of the present invention, the specific cell information includes information on a plurality of cells connected to the mobile station apparatus communicating with the first base station apparatus. To do.

  (4) In the communication system of the present invention, the specific cell information includes a cell identifier and / or a cell frequency band.

  (5) Moreover, the base station apparatus in the communication system of the present invention includes a plurality of base station apparatuses and mobile station apparatuses, and the mobile station apparatus uses the cells of a plurality of frequency bands at the same time, A base station apparatus in a communication system for connecting and communicating, wherein the base station apparatus receives specific cell information from another base station apparatus and communicates simultaneously with the mobile station apparatus including the specific cell. A combination of cells that can be performed is specified, and all or some of the specified combinations are activated.

  (6) Moreover, the base station apparatus in the communication system of the present invention includes a plurality of base station apparatuses and mobile station apparatuses, and the mobile station apparatus uses the cells of a plurality of frequency bands at the same time, A base station apparatus in a communication system for connecting and communicating, wherein the base station apparatus selects a specific cell based on a measurement result from the mobile station apparatus communicating with the controlled cell, and In order to activate a cell that can communicate simultaneously with the mobile station apparatus including the cell, a message including the specific cell information is notified to a base station apparatus that controls the specific cell. It is characterized by.

  (7) Further, the communication method of the present invention includes a plurality of base station apparatuses and mobile station apparatuses, and the mobile station apparatus communicates with the base station apparatus using a plurality of frequency band cells simultaneously. A communication method in a communication system for performing communication, wherein the plurality of base station apparatuses include a first base station apparatus and a second base station apparatus, and the first base station apparatus is configured to transmit the second base station. Transmitting a message including specific cell information to a device, and specifying a combination of cells in which the second base station device can communicate simultaneously with the mobile station device including the specific cell And activating all or some of the specified combinations of cells.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the radio | wireless communications system, base station apparatus, and communication method which can control an inactive state cell efficiently, suppressing network load.

It is a block diagram which shows an example of the mobile station apparatus in the 1st Embodiment of this invention. It is a block diagram which shows an example of the base station apparatus in the 1st Embodiment of this invention. It is the sequence chart which showed the measurement and handover procedure in the 1st Embodiment of this invention. It is the sequence chart which showed the measurement and the handover procedure in the 2nd Embodiment of this invention. It is the sequence chart which showed the measurement and handover procedure in the 3rd Embodiment of this invention. It is a figure which shows an example of the communication network structure which concerns on embodiment of this invention. It is the sequence chart which showed the conventional measurement and the handover procedure.

Before describing embodiments of the present invention, physical channels and carrier aggregation related to the present invention will be described.

[Physical channel]
A physical channel (or physical signal) used in EUTRA and Advanced EUTRA will be described. The physical channel includes a downlink channel in the downlink transmitted from the base station apparatus to the mobile station apparatus, and an uplink channel in the uplink transmitted from the mobile station apparatus to the base station apparatus. The physical channel may be added or changed in the future in EUTRA and Advanced EUTRA. However, even if the physical channel is changed, the description of each embodiment of the present invention is not affected.

  Synchronization signals are composed of three types of primary synchronization signals and secondary synchronization signals composed of 31 types of codes arranged alternately in the frequency band. Depending on the combination, 504 kinds of cell identifiers (cell ID, PCI; Physical Cell Identifier) for identifying the base station apparatus and frame timing for radio synchronization are shown. The mobile station device specifies the cell ID of the synchronization signal received by the cell search.

  A physical broadcast information channel (PBCH; Physical Broadcast Channel) is transmitted for the purpose of notifying control parameters (broadcast information (system information): System information) commonly used by mobile station apparatuses in a cell. The broadcast information not notified by the physical broadcast information channel is transmitted by a layer 3 message (system information) using the downlink data channel, with the radio resource notified by the downlink control channel. As broadcast information, a cell global identifier (CGI) indicating a cell-specific identifier, a tracking area identifier (TAI) for managing a paging standby area, a cell frequency bandwidth, downlink and uplink The correspondence relationship of the frequency band is notified.

  The downlink reference signal is a pilot signal transmitted at a predetermined power for each cell. The downlink reference signal is a known signal that is periodically repeated at a frequency / time position based on a predetermined rule. The mobile station apparatus measures the reception quality for each cell by receiving the downlink reference signal. The mobile station apparatus also uses the downlink reference signal as a reference signal for demodulation of the downlink control channel or downlink data channel transmitted simultaneously with the downlink reference signal. As a sequence used for the downlink reference signal, a sequence that can be identified for each cell is used. In addition, although a downlink reference signal may be described as cell-specific reference signal (RS), the use and meaning are the same.

  A downlink control channel (PDCCH; Physical Downlink Control Channel) is transmitted in several OFDM symbols from the beginning of each subframe. Radio resource allocation information according to the scheduling of the base station device and transmission to the mobile station device Used to indicate the amount of power increase / decrease adjustment. The mobile station apparatus monitors (monitors) the downlink control channel addressed to itself before transmitting / receiving the layer 3 message (paging, handover command, etc.) that is downlink data or downlink control data, and By receiving the downlink control channel, it is necessary to acquire radio resource allocation information called an uplink grant at the time of transmission and a downlink grant at the time of reception.

  A downlink data channel (PDSCH: Physical Downlink Shared Channel) is used to notify paging and broadcast information as a layer 3 message that is downlink control data in addition to downlink data. The radio resource allocation information of the downlink data channel is indicated by the downlink control channel.

  An uplink data channel (PUSCH) mainly transmits uplink data and uplink control data, and can also include control data such as downlink reception quality and ACK / NACK. Similarly to the downlink, the radio resource allocation information of the uplink data channel is indicated by the downlink control channel.

  A random access channel (PRACH) is a channel used for notifying a preamble sequence and has a guard time. The random access channel is used as a means for accessing the base station apparatus of the mobile station apparatus. The mobile station apparatus uses a random access channel for a request for scheduling transmission data when the uplink control channel is not set and a request for transmission timing adjustment information necessary for matching the uplink transmission timing with the reception timing window of the base station apparatus. . The mobile station apparatus that has received the transmission timing adjustment information sets an effective time of the transmission timing adjustment information, and manages the state as a transmission timing adjustment state during the effective time and as a transmission timing non-adjustment state outside the effective period. The base station device can also start random access by assigning a dedicated preamble sequence (Dedicated preamble) to the mobile station device. Since other physical channels are not related to each embodiment of the present invention, detailed description thereof is omitted.

[Career aggregation]
Carrier aggregation is a technology that aggregates (aggregates) a plurality of different uplink or downlink frequency bands (component carriers) and treats them as one frequency band. For example, when five component carriers having a frequency bandwidth of 20 MHz are aggregated by carrier aggregation, the mobile station apparatus can access the mobile station apparatus by regarding it as a frequency bandwidth of 100 MHz. The component carriers to be aggregated may be a continuous frequency band, or may be a frequency band in which all or part of them are discontinuous. For example, when the usable frequency band is an 800 MHz band, a 2.4 GHz band, and a 3.4 GHz band, one component carrier is an 800 MHz band, another component carrier is a 2 GHz band, and another component carrier is 3.4 GHz. It may be transmitted in a band.

  It is also possible to aggregate continuous or discontinuous component carriers in the same frequency band, for example, the 2.4 GHz band. The frequency bandwidth of each component carrier may be a frequency bandwidth narrower than 20 MHz, or may be different from each other.

  Hereinafter, in the present embodiment, description will be made using three frequencies F1, F2, and F3 as an example, but each frequency may be a different frequency band as described above, or may be a frequency of different component carriers in the same frequency band.

  Further, the base station apparatus can assign uplink or downlink component carriers to the mobile station apparatus based on various factors such as the transmission data buffer amount of the mobile station apparatus, the reception quality of the mobile station apparatus, the load in the cell and QoS. The number of can be increased or decreased.

  In addition, the component carrier is identified as a primary component carrier (PCC) and a secondary component carrier (SCC; Secondary Component Carrier). The primary component carrier is typically composed of a pair of uplink component carrier and downlink component carrier indicated by broadcast information, and the mobile station apparatus performs measurement control or downlink radio link failure (Radio Link Failure). This is a frequency band that serves as a reference for detection and transmission of the uplink control channel. In the base station apparatus, the primary component carrier can be set for each mobile station apparatus.

  The secondary component carrier is a frequency band assigned to a mobile station device other than the primary component carrier. The mobile station device does not need to detect a radio link failure with the secondary component carrier. The base station apparatus can also instruct the mobile station apparatus to validate / invalidate the secondary component carrier allocated for power saving. The mobile station apparatus attempts to receive the downlink data channel by monitoring the downlink control channel only in the cell of the enabled secondary component carrier, and monitors the downlink control channel in the cell of the disabled secondary component carrier. It is also possible to measure only the reception quality without doing so.

  That is, the mobile station apparatus classifies the component carrier states into (1) a set and enabled state, (2) a set but disabled state, and (3) a non-set state. to manage. Further, by omitting the status of validation / invalidation of the secondary component carrier, the mobile station apparatus may be configured to manage only two statuses of whether or not the secondary component carrier is simply set. good.

  In the present invention, the expression “activation / deactivation” of the component carrier is used as described above. However, the expression “activation / deactivation” may be generally used. However, in the present invention, the state in which the wireless transmission / reception of the cell is performed is activated, the state in which the wireless transmission / reception is stopped (all or a part thereof) is inactivated, and the change in the state of wireless transmission / reception is activated / Inactivated.

[Example of communication network configuration of the present invention]
FIG. 6 is a diagram illustrating an example of a communication network configuration according to the embodiment of the present invention. When the mobile station apparatus 1 can be wirelessly connected to the base station apparatus 2 by simultaneously using cells in a plurality of frequency bands (component carriers, Band1 to Band3) by carrier aggregation, there is a certain communication network configuration. One base station apparatus 2 includes transmission apparatuses 11 to 13 (and reception apparatuses 21 to 23 (not shown)) for each of a plurality of frequency bands, and a configuration in which one base station apparatus 2 controls cells in each frequency band. This is preferable from the viewpoint of simplification of control. However, the base station apparatus 2 may be configured to transmit a plurality of frequency bands with a single transmission apparatus, for example, because the plurality of frequency bands are continuous frequency bands. The communicable range of each frequency band controlled by the transmission apparatus of the base station apparatus 2 is regarded as a cell and exists in the same spatial area. At this time, the areas (cells) covered by each frequency band may have different sizes and shapes. Further, a communication network configuration in which a frequency band that is carrier-aggregated by a plurality of base station apparatuses 2 is managed, and a higher-level control station apparatus manages the plurality of base station apparatuses 2 may be employed.

  The cell of the primary component carrier set in the mobile station apparatus 1 is a primary serving cell (Primary Serving Cell (PCell) or simply serving cell (Serving Cell)), and the cell of the secondary component carrier is a secondary serving cell (Secondary Serving Cell). (SCell)). That is, the mobile station apparatus 1 that performs carrier aggregation is connected to the base station apparatus 2 via a primary serving cell and one or more secondary serving cells.

  Note that the third generation base station apparatus 2 defined by 3GPP is referred to as a Node B (NodeB), and the base station apparatus 2 in EUTRA and Advanced EUTRA is referred to as an eNodeB (eNodeB). The base station device 2 manages a cell that is an area where the mobile station device 1 can communicate, and the cell is also referred to as a femto cell, a pico cell, or a nano cell depending on the size of the area that can communicate with the mobile station device 1. Further, when the mobile station device 1 can communicate with a certain base station device 2, the cell of the base station device 2 is a serving cell of the mobile station device 1, and the cells of the other base station devices 2 are neighboring cells. Called.

  In the description to be described later, each area covered by the frequency of the component carrier formed by the base station apparatus 2 will be referred to as a cell, but this may be different from the definition of the cell in the actually operated communication system. Note that there is sex. For example, some communication systems may define some of the component carriers used by carrier aggregation as simply additional radio resources rather than cells. By referring to the component carrier as a cell in the present invention, even if a case different from the definition of the cell in the actually operated communication system occurs, the gist of the present invention is not affected. The mobile station device 1 may be wirelessly connected to the base station device 2 via a relay station device (or repeater).

[Measurement and handover]
FIG. 7 is a sequence chart for explaining a measurement setting management method for the mobile station apparatus 1 and the base station apparatus 2 before and after handover in EUTRA.

  In the example of FIG. 7, cells managed by the mobile station apparatus 1 and a plurality of base station apparatuses 2 (cells A, B, C, and C managed by the base station apparatus 2B as cells managed by the base station apparatus 2A here) Cell D, cell E, and cell F), and the mobile station apparatus 1 is in a state (RRC_Connected state) in which radio connection is established in the cell A (frequency F1) and cell B (frequency F2) of the base station apparatus 2A. Yes, cell A is PCell and cell B is SCell.

  First, the base station device 2A transmits to the mobile station device 1 a measurement setting message for measuring the reception quality of the cell A and the cell B (located cell) in communication and other cells (neighboring cells) ( Step S701). The measurement setting message includes at least one measurement setting information for each frequency (frequency F1, F2, F3) to be measured. The measurement setting information includes a measurement ID, a measurement object frequency (measurement object), a measurement object frequency ID corresponding to the measurement object frequency, a report setting including a measurement event, and a report setting ID corresponding to the report setting. Is done. A plurality of report setting IDs may be linked to one measurement target frequency ID. Similarly, one report setting ID may be linked to a plurality of measurement target frequency IDs.

  The measurement event is, for example, when the reception quality of the serving cell is below / above a predetermined threshold, or when the reception quality of the neighboring cell is lower than the serving cell, the reception quality of the neighboring cell is a predetermined threshold. It is information composed of a condition such as when the value exceeds, and a parameter used to determine the condition. The parameter is set with a threshold, an offset value, a time required for establishment of a measurement event, and the like.

  In step S702, the mobile station apparatus 1 stores the measurement setting information set from the base station apparatus 2 as internal information, and then starts the measurement process. Specifically, the mobile station apparatus 1 manages the measurement ID, the measurement target frequency ID, and the report setting ID so that they are linked together, and starts measurement based on the measurement information corresponding to each ID. . If these three IDs are linked to one, it is considered valid and the associated measurement is started. If these three IDs are not linked to one (one of the IDs is not set) ), The relevant measurement is not started as invalid. If the measurement setting information can be set without error, the mobile station apparatus 1 transmits a measurement setting completion message to the base station apparatus 2A in step S703.

  When any of the set measurement events satisfies the condition according to the parameter, the mobile station device 1 transmits a measurement report message to the base station device 2A, assuming that the measurement event is triggered. (Step S704). In the measurement report message, at least the measurement ID linked to the report setting ID of the triggered measurement event and, if necessary, the measurement result of the associated cell are set. Since the base station device 2 knows to which measurement event report setting ID the measurement ID is linked, the mobile station device 1 does not need to notify the report setting ID in the measurement report message.

  The base station apparatus 2 considers the measurement report message from the mobile station apparatus 1, the system load, the state of interference, etc., and performs handover to the optimal cell for the mobile station apparatus 1 and addition or deletion of SCells as necessary. Etc. are determined (step S705). For example, when the reception quality of the cell B decreases and the reception quality of the cell C increases, the cell C can be deleted as the SCell and the cell C can be added. Here, the case where the reception quality of the cell D becomes high will be described.

  The base station device 2A transmits a handover request message to the base station device 2B that controls the cell D in order to hand over the mobile station device 1 from the cell A to the cell D (step S706). The handover request information sent in the handover request message includes information related to resources necessary for communication with the mobile station apparatus 1, and when the mobile station apparatus 1 is performing carrier aggregation, the measurement result of another cell Information about the content may be included. That is, when the mobile station apparatus 1 is performing carrier aggregation, by including information on the measurement result of the cell under the control of the base station apparatus 2B in the handover request message, handover is performed while maintaining the state of carrier aggregation. Can be performed.

  When the base station apparatus 2B that has received the handover request message can prepare resources necessary for communication with the mobile station apparatus 1 in the cell D, security information necessary for connection with the cell D or random information can be used as a handover request response. The information including the information used for access is notified to the base station apparatus 2A (step S707). If the mobile station apparatus 1 cannot be accepted, the base station apparatus 2A is notified of the failure of handover preparation as a handover request response. Moreover, when the information regarding the measurement result of the other cell under control of the base station apparatus 2B is included in the handover request information, the handover request response may include specifying cell E (or cell F) as the SCell.

  The base station apparatus 2A that has received the handover request response gives a handover instruction to the cell D to the mobile station apparatus 1 if the handover is possible (step S708). The handover instruction message includes system information necessary for connection with the cell D, information about security, information used for random access, and the like. If the SCell information is included in the handover request response, the information may be included in the handover instruction message.

  The mobile station apparatus 1 that has received the handover instruction tries to connect to the cell D, and when the connection is successful, notifies the base station apparatus 2B of a handover completion message (step S709).

  Receiving the handover completion message, the base station device 2B notifies the base station device 2A of permission to release radio resources and control information related to the mobile station device 1 to the base station device 2A to complete the handover (S710).

  Although not specified in the above procedure, user data for the mobile station apparatus 1 is transferred from the base station apparatus 2A to the base station apparatus 2B after the handover instruction, and transmission is continued to the mobile station apparatus 1 after the handover is completed. .

  Considering the above matters, preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that in the description of the present invention, detailed description of what is determined to obscure the gist of the present invention will be omitted for the specific description of known functions and configurations related to the present invention.

[First Embodiment]
A first embodiment of the present invention will be described below. The present embodiment relates to a control method for an activation request signal based on a neighbor cell measurement result accompanying a decrease in PCell reception quality reported from the mobile station apparatus 1 during carrier aggregation.

  FIG. 1 is a block diagram showing an example of a mobile station apparatus 1 according to the embodiment of the present invention. The mobile station apparatus 1 includes a reception unit 101, a demodulation unit 102, a decoding unit 103, a measurement processing unit 104, a control unit 105, a random access processing unit 106, a coding unit 107, a modulation unit 108, a transmission unit 109, and an upper layer 110. Composed. Prior to reception, mobile station apparatus control information is input from the upper layer 110 to the control unit 105, and the mobile station apparatus control information related to reception is received as reception control information. The reception unit 101, demodulation unit 102, decoding unit 103, and measurement processing unit 104 Is entered appropriately. The reception control information includes information such as demodulation information, decoding information, reception frequency band information, reception timing for each channel, multiplexing method, and radio resource arrangement information as reception schedule information.

  The received signal is received by the receiving unit 101 via one or more antennas (not shown). The receiving unit 101 receives a signal in the frequency band notified by the reception control information. The receiving unit 101 includes a baseband processing unit for received signals. The received signal is input to demodulator 102. Demodulation section 102 demodulates the received signal and inputs the received signal to decoding section 103. The decoding unit 103 correctly decodes the received signal based on the reception control information. Decoding section 103 appropriately separates the received signal into downlink traffic data and downlink control data, and inputs the separated signals to higher layer 110, respectively.

  In addition, the decoding unit 103 inputs a decoded received signal related to measurement to the measurement processing unit 104. The measurement processing unit 104 performs measurement processing of the reception quality of the downlink reference signal for each cell and measurement processing of the reception error rate of the downlink control channel or the downlink data channel, and averages the measured reception quality for each sample. (Filtered) downlink measurement information is generated, and the downlink measurement information is output to the upper layer 110. In addition, the measurement processing unit 104 compares the obtained reception quality with a threshold (also referred to as Qout) used for detecting a downlink synchronization error, and outputs a downlink synchronization error to the upper layer 110 as necessary.

  Prior to transmission, mobile station apparatus control information is input from the upper layer 110 to the control section 105, and the mobile station apparatus control information related to transmission is transmitted as control information, a random access processing section 106, an encoding section 107, a modulation section 108, An appropriate input is made to the transmission unit 109. The transmission control information includes information such as encoding information, modulation information, transmission frequency band information, transmission timing for each channel, multiplexing method, and radio resource arrangement information as uplink scheduling information of the transmission signal. Random access processing unit 106 receives random access information necessary for transmission of a random access channel such as radio resource information necessary for random access and the maximum number of transmissions from upper layer 110. Further, when the random access processing unit 106 detects the random access problem by counting the number of transmissions of the random access channel, the random access processing unit 106 notifies the upper layer 110 of random access problem information indicating that the random access problem has occurred.

  The encoding unit 107 is appropriately input with uplink traffic data and uplink control data from the upper layer 110 and random access data from the random access processing unit 106 according to the uplink channel. The encoding unit 107 appropriately encodes each data according to the transmission control information and outputs the data to the modulation unit 108. The modulation unit 108 modulates the input from the coding unit 107.

  Transmitting section 109 maps the output of modulating section 108 to a frequency band, converts a frequency band signal into a time domain signal, performs power amplification on a predetermined frequency carrier wave, and transmits the signal. An uplink data channel in which uplink control data is arranged typically constitutes a layer 3 message (radio resource control message; RRC message). The RRC of the mobile station device 1 exists as part of the upper layer 110. The random access processing unit 106 exists as part of a MAC (Medium Access Control) that manages the data link layer of the mobile station apparatus 1. In FIG. 1, the other components of the mobile station apparatus 1 are omitted because they are not related to the present embodiment.

  FIG. 2 is a block diagram showing an example of the base station apparatus 2 according to the embodiment of the present invention. The base station apparatus 2 includes a reception unit 201, a demodulation unit 202, a decoding unit 203, a control unit 204, a coding unit 205, a modulation unit 206, a transmission unit 207, a network signal processing unit 208, a peripheral information management unit 209, and an upper layer 210. And a carrier aggregation information management unit 211.

  Upper layer 210 inputs downlink traffic data and downlink control data to encoding section 205. The encoding unit 205 encodes each input data and inputs the data to the modulation unit 206. Modulation section 206 modulates the encoded signal. Also, in the modulation unit 206, the downlink reference signal is multiplexed with the modulated signal and mapped to the frequency band. The transmission unit 207 converts the frequency band signal output from the modulation unit 206 into a time domain signal, places the converted signal on a carrier having a predetermined frequency, performs power amplification and transmits the signal. A downlink data channel in which downlink control data is arranged typically forms a layer 3 message (RRC message).

  In addition, the reception unit 201 converts a reception signal from the mobile station apparatus 1 into a baseband digital signal. The digital signal is input to the demodulation unit 202 and demodulated. The signal demodulated by the demodulator 202 is subsequently input to the decoder 203 and decoded. The decoding unit 203 appropriately separates the received signal into uplink traffic data and uplink control data, and inputs each to the higher layer 210.

  Base station apparatus control information necessary for the control of each block is input from the upper layer 210 to the control unit 204, and the base station apparatus control information related to transmission is transmitted from the control unit 204 as transmission control information as a coding unit 205, modulation. Base station apparatus control information related to reception is appropriately input to each block of the reception unit 201, demodulation unit 202, and decoding unit 203 as reception control information in each block of the unit 206 and transmission unit 207.

  On the other hand, the network signal processing unit 208 transmits or receives a control message between a plurality of base station apparatuses 2 (or control station apparatus (MME), gateway apparatus (Gateway), relay station apparatus) and the base station apparatus 2. To do. Control messages are transmitted and received via a network line. The peripheral information management unit 209 manages network information for specifying the transmission destination or transmission source base station device 2 (or control station device, gateway device, relay station device). The network information can specify the address of each device on the network such as a tracking area identifier (TAI), a cell global identifier (CGI), a cell identifier (PCI), a network color code, an Internet protocol address (IP address), etc. Consists of information. Control messages are exchanged on a logical interface called an X2 interface. The network line is typically a wired line, but may be a wireless line when communicating with a relay station device, for example.

  The peripheral information management unit 209 provides network information to the network signal processing unit 208 as necessary. The network signal processing unit 208 and the peripheral information management unit 209 are managed by an upper layer. The RRC of the base station device 2 exists as a part of the upper layer 210. Also, the carrier aggregation information management unit 211 holds information on combinations that can be carrier-aggregated in cells under the control of the base station device 2 (or including cells under control of other base station devices 2). In FIG. 2, the other components of the base station apparatus 2 are omitted because they are not related to the present embodiment.

  Next, measurement and handover will be described. In the present embodiment, similarly to the description using FIG. 7 described above, the mobile station device 1 is in a state (RRC_Connected) in which radio connection is established in the cell A (frequency F1) and the cell B (frequency F2) of the base station device 2A. State), cell A is PCell, and cell B is SCell. In addition, it is assumed that the cell E (frequency F2) and the cell F (frequency F3) of the base station apparatus 2B stop radio transmission for power saving.

First, the case where the conventional technique is used will be described. When the mobile station apparatus 1 measures neighboring cells in the above situation, the radio quality of the cell E and the cell F cannot be measured, and handover cannot be performed while maintaining carrier aggregation. Therefore, conventionally, the base station apparatus 2A wakes up one or more base station apparatuses 2 that control neighboring cells in the Deactivation state (cells in other Deactivation states including the cell E and the cell F). A signal is transmitted and measurement is performed in the activation state. However, in the above method, when the base station apparatus 2A does not hold the combination information of the cells that can be carrier-aggregated in the base station apparatus 2B, the unnecessary cell is set in the activation state and unnecessary radio transmission is generated. There is a possibility to make it.
Next, the measurement and handover procedures in this embodiment are shown in the sequence chart of FIG.

  First, measurement settings similar to those described with reference to FIG. 7 are performed between the base station apparatus 2A and the mobile station apparatus 1 (steps S301 to S303).

  Next, when any of the set measurement events satisfies the condition according to the parameter, the mobile station apparatus 1 transmits a measurement report message to the base station apparatus 2A on the assumption that the measurement event is triggered. (Step S304). At this stage, measurement of the cells E and F in the Deactivation state has not been performed.

  The base station apparatus 2 considers the measurement report message from the mobile station apparatus 1, the system load, the state of interference, etc., and performs handover to the optimal cell for the mobile station apparatus 1 and addition or deletion of SCells as necessary. Etc. are determined (step S305). Here, the case where the reception quality of the cell D becomes high will be described.

  In order to hand over the mobile station device 1 from the cell A to the cell D, the base station device 2A first sets a cell capable of carrier aggregation together with the cell D to the activation state for the base station device 2B that controls the cell D. The request message is transmitted to the base station apparatus 2B that controls the cell D (step S306). This message does not need to include individual cell identifiers (CGI and PCI) to be activated as in the conventional case, but includes information on cell D (CGI and PCI).

  The base station apparatus 2B that has received the Wakeup request message acquires information on cells that can be subjected to carrier aggregation including the cell D from the carrier aggregation information management unit 211, and acquires the cell acquired from the carrier aggregation information management unit 211. If there is a cell in the Deactivation state, all or a part of the cell is set in the Activation state, and a Wakeup request response is notified to the base station apparatus 2A (step S307). The Wakeup request response may include information (PCI, CGI, frequency information, etc.) related to the cell in the activation state.

  The base station apparatus 2A that has received the Wakeup request response performs measurement setting with the mobile station apparatus 1 again if necessary (steps S309 to S311), and based on the measurement report reported from the mobile station apparatus 1 (step S312), a cell to be connected (here, cell D) is selected (step S313), and a handover request message is transmitted to the base station apparatus 2B that controls the cell D (step S314). The handover request information sent in the handover request message includes information on the measurement results of neighboring cells (cell E and cell F).

  When the base station apparatus 2B that has received the handover request message can prepare resources necessary for communication with the mobile station apparatus 1 in the cell D, security information necessary for connection with the cell D or random information can be used as a handover request response. The base station apparatus 2A is notified including information used for access (step S315). In addition, the handover request response may include contents for designating a specific cell (cell E or cell F) as an SCell.

  The base station device 2A that has received the handover request response gives a handover instruction to the cell D to the mobile station device 1 when the handover is possible (step S316). The handover instruction message includes system information necessary for connection with the cell D, information about security, information used for random access, and the like. If the SCell information is included in the handover request response, the information may be included in the handover instruction message.

  Receiving the handover instruction, the mobile station apparatus 1 tries to connect to the cell D, and when the connection is successful, notifies the base station apparatus 2B of a handover completion message (step S317).

  Receiving the handover completion message, the base station device 2B notifies the base station device 2A of permission to release radio resources and control information related to the mobile station device 1 to the base station device 2A to complete the handover (step S318). .

  According to the present embodiment, unlike the prior art, only the cells related to the carrier aggregation of the handover destination cell of the mobile station apparatus 1 can be efficiently performed without transmitting the Wakeup signal to all the neighboring cells in the Deactivation state. It is possible to enter the activation state. Furthermore, unnecessary radio transmission (activation) of a cell incapable of carrier aggregation is prevented by activating only a cell that can be carrier-aggregated and an optimal cell as a handover candidate of the mobile station apparatus 1. It becomes possible. Further, according to the present embodiment, it is possible to activate only the cells capable of carrier aggregation without exchanging the combination information of the cells capable of carrier aggregation between the plurality of base station apparatuses 2.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described. The present embodiment relates to an activation request signal control method based on a carrier aggregation setting state applied to the mobile station apparatus 1. Since the communication system (mobile station apparatus and base station apparatus) used in the description of the present embodiment is the same as that of the first embodiment, the description thereof is omitted. Also in the present embodiment, as in the first embodiment, the mobile station apparatus 1 is in a state (RRC_Connected state) in which radio connection is established in the cell A (frequency F1) and the cell B (frequency F2) of the base station apparatus 2A. ), Cell A is PCell, and cell B is SCell. In addition, it is assumed that the cell E (frequency F2) and the cell F (frequency F3) of the base station apparatus 2B stop radio transmission for power saving.

  Measurement and handover procedures in the present embodiment are shown in the sequence chart of FIG.

  First, the base station apparatus 2A performs PCell assignment (here, cell A at frequency F1) and SCell assignment (here, cell C at frequency F3) as carrier aggregation settings with the mobile station apparatus 1. (Step S401).

  Next, the base station apparatus 2A sends a wakeup request message including frequency information (frequency F1 and frequency F3 in this case) being used for carrier aggregation in the base station apparatus 2A to the base station apparatus 2B that controls an adjacent cell. Then, it transmits to the base station apparatus 2B (step S402). Here, a Wakeup request message is used, but a message notifying only the frequency information may be used. In this case, since it is not a request, there is no need for a response (S404) described later.

  Receiving the Wakeup request message, the base station device 2B selects a combination of cells that can perform carrier aggregation based on the frequency information included in the message, and controls the selected cell controlled by the own base station device. All or a part is set in the activation state (step S403), and a wakeup request response is notified to the base station apparatus 2A (step S404). The Wakeup request response may include information (PCI, CGI, frequency information, etc.) related to the cell in the activation state.

  The base station apparatus 2A that has received the Wakeup request response performs measurement settings with the mobile station apparatus 1 (steps S405 to S407), and based on the measurement report reported from the mobile station apparatus 1 (step S408), the connection destination A cell (here, cell D of frequency F1) is selected (step S409), and a handover request message is transmitted to the base station apparatus 2B that controls cell D (step S410). When the cell F has been activated in step S403, the handover request information sent in the handover request message may include information on the measurement result of the neighboring cell (cell F of frequency F3).

  When the base station apparatus 2B that has received the handover request message can prepare resources necessary for communication with the mobile station apparatus 1 in the cell D, security information necessary for connection with the cell D or random information can be used as a handover request response. The information including the information used for access is notified to the base station apparatus 2A (step S411). In addition, the handover request response may include content specifying a specific cell (here, cell F) as an SCell.

  The base station apparatus 2A that has received the handover request response gives a handover instruction to the cell D to the mobile station apparatus 1 if the handover is possible (step S412). The handover instruction message includes system information necessary for connection with the cell D, information about security, information used for random access, and the like. If the SCell information is included in the handover request response, the information may be included in the handover instruction message.

  Receiving the handover instruction, the mobile station apparatus 1 tries to connect to the cell D, and when the connection is successful, notifies the base station apparatus 2B of a handover completion message (step S413).

  Receiving the handover complete message, the base station device 2B notifies the base station device 2A of permission to release radio resources and control information related to the mobile station device 1 to the base station device 2A to complete the handover (step S414). .

  According to the present embodiment, as in the prior art, only the cells capable of carrier aggregation that can be the handover destination of the mobile station apparatus 1 are efficiently transmitted without transmitting the Wakeup signal to all the neighboring cells in the Deactivation state. Thus, it is possible to set the activation state. Furthermore, unnecessary radio transmission (activation) of a cell incapable of carrier aggregation is prevented by activating only a cell that can be carrier-aggregated and an optimal cell as a handover candidate of the mobile station apparatus 1. It becomes possible. Further, according to the present embodiment, it is possible to activate only the cells capable of carrier aggregation without exchanging the combination information of the cells capable of carrier aggregation between the plurality of base station apparatuses 2.

  In this embodiment, the base station apparatus 2A designates a frequency and makes a wakeup request. However, the frequency information of the carrier aggregation that is set in the base station apparatus 2A and communication is continued is transmitted to the neighboring cells. You may make it notify to the base station apparatus 2 (base station apparatus 2B here) to control. The base station apparatus 2 notified of the information can autonomously control the activation / deactivation state of the cell under control based on the frequency usage situation of the neighboring cells.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described. The present embodiment relates to an activation request method using a handover request message. Since the communication system (mobile station apparatus and base station apparatus) used in the description of the present embodiment is the same as that of the first embodiment, the description thereof is omitted. Also in the present embodiment, as in the first embodiment, the mobile station apparatus 1 is in a state (RRC_Connected state) in which radio connection is established in the cell A (frequency F1) and the cell B (frequency F2) of the base station apparatus 2A. ), Cell A is PCell, and cell B is SCell. In addition, it is assumed that the cell E (frequency F2) and the cell F (frequency F3) of the base station apparatus 2B stop radio transmission for power saving.

  Measurement and handover procedures in this embodiment are shown in the sequence chart of FIG.

  First, measurement settings similar to those described in FIG. 7 are performed between the base station device 2A and the mobile station device 1 (steps S501 to S503).

  Next, when any of the set measurement events satisfies the condition according to the parameter, the mobile station apparatus 1 transmits a measurement report message to the base station apparatus 2A on the assumption that the measurement event is triggered. (Step S504). At this stage, measurement of the cells E and F in the Deactivation state has not been performed.

  The base station apparatus 2 considers the measurement report message from the mobile station apparatus 1, the system load, the state of interference, etc., and performs handover to the optimal cell for the mobile station apparatus 1 and addition or deletion of SCells as necessary. Etc. are determined (step S505). Here, the case where the reception quality of the cell D becomes high will be described.

  The base station device 2A transmits a handover request message to the base station device 2B that controls the cell D in order to hand over the mobile station device 1 from the cell A to the cell D (step S506). The handover request information sent in the handover request message includes information on the identifier of the cell desired to be handed over (here, CGI and PCI of cell D), current bit rate information, and the like. The handover request information includes reception quality information or frequency information of the PCell or SCell of the base station apparatus 2A. Or not only PCell and SCell but the information of the frequency which the mobile station apparatus 1 can communicate may be included.

  The base station apparatus 2B that has received the handover request message determines whether or not the resources necessary for communication with the mobile station apparatus 1 can be prepared in the cell D. The base station apparatus 2A is notified including security information necessary for connection with the cell D, information used for random access, and the like. When the resource cannot be prepared, the base station apparatus 2B activates a cell capable of carrier aggregation from the information included in the handover request information (step S507), and notifies a message requesting remeasurement as a handover request response (step S508). ). The handover request response may include cell information to be remeasured. In addition, although the remeasurement request is notified here, it may be merely notified that the inactive cell is activated.

  The base station device 2A that has received the handover request response gives a handover instruction to the cell D to the mobile station device 1 as in the conventional case when the handover is possible (step S514). However, when handover is impossible and a remeasurement request is received, measurement setup is performed again with the mobile station apparatus 1 in order to add a cell to be remeasured to the measurement target if necessary (step S509 to S511), a measurement report is received from the mobile station device 1 (step S512). Then, based on the reported measurement report, a connection destination cell (here, cell D) is selected (step S513), and a handover request message is transmitted to the base station apparatus 2B that controls the cell D (step S514). . The handover request information sent in the handover request message includes information on the measurement results of neighboring cells (cell E and cell F).

  When the base station apparatus 2B that has received the handover request message can prepare resources necessary for communication with the mobile station apparatus 1 in the cell D and the cell that performs carrier aggregation, the base station apparatus 2B establishes a connection with the cell D as a handover request response. The base station apparatus 2A is notified including necessary security information and information used for random access (step S515). In addition, the handover request response may include contents for designating a specific cell (cell E or cell F) as an SCell.

  Receiving the handover request response, the base station apparatus 2A gives a handover instruction to the cell D to the mobile station apparatus 1 if the handover is possible (step S516). The handover instruction message includes system information necessary for connection with the cell D, information about security, information used for random access, and the like. If the SCell information is included in the handover request response, the information may be included in the handover instruction message.

  The mobile station apparatus 1 that has received the handover instruction tries to connect to the cell D, and when the connection is successful, notifies the base station apparatus 2B of a handover completion message (step S517).

  Receiving the handover complete message, the base station device 2B notifies the base station device 2A of permission to release radio resources and control information related to the mobile station device 1 to the base station device 2A to complete the handover (step S518). .

  According to the present embodiment, by using a handover request without transmitting a Wakeup signal as in the prior art, only cells related to carrier aggregation of a handover destination cell of the mobile station apparatus 1 can be obtained as in the Wakeup signal. It is possible to efficiently enter the activation state. Furthermore, unnecessary radio transmission (activation) of a cell incapable of carrier aggregation is prevented by activating only a cell that can be carrier-aggregated and an optimal cell as a handover candidate of the mobile station apparatus 1. It becomes possible. Further, according to the present embodiment, it is possible to activate only the cells capable of carrier aggregation without exchanging the combination information of the cells capable of carrier aggregation between the plurality of base station apparatuses 2.

  In addition, the cell activated in each said embodiment may return to an inactive state based on a predetermined condition. For example, when a handover is not executed within a certain time from a Wakeup request, when communication in a cell is not observed for a certain time, when a cancellation or termination of a request is notified from the cell that made the Wakeup request, Examples include combinations of the above conditions.

  In each of the above embodiments, a wakeup request or a handover request is exchanged between the base station apparatuses 2, but a message may be exchanged directly between the base station apparatuses 2, or via a higher-level control apparatus. You may exchange.

  The embodiment according to the present invention has been described above. However, with respect to the base station apparatus according to the present invention, the functions of each unit of the base station apparatus or a program for realizing a part of these functions can be read by a computer. The control shown in each embodiment may be performed by recording on a recording medium, reading the program recorded on the recording medium into a computer system, and executing the program. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, it is also assumed that a server that holds a program for a certain time, such as a volatile memory inside a computer system that serves as a server or client. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  Each functional block used in each of the above embodiments may be realized as an LSI that is typically an integrated circuit. Each functional block may be individually formed into chips, or a part or all of them may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology can also be used.

  As mentioned above, although embodiment of this invention has been explained in full detail based on the specific example, it is clear that the meaning of this invention and a claim are not limited to these specific examples. In other words, the description in the present specification is for illustrative purposes and does not limit the present invention.

DESCRIPTION OF SYMBOLS 1 ... Mobile station apparatus 2 ... Base station apparatus 11, 12, 13 ... Transmission apparatus 101, 201 ... Reception part 102, 202 ... Demodulation part 103, 203 ... Decoding part 104 ... Measurement processing part 105, 204 ... Control part 106 ... Random Access processing unit 107, 205 ... Encoding unit 108, 206 ... Modulation unit 109, 207 ... Transmission unit 110, 210 ... Upper layer 208 ... Network signal transmission / reception unit 209 ... Peripheral information management unit 211 ... Carrier aggregation information management unit

Claims (7)

A communication system comprising a plurality of base station devices and mobile station devices, wherein the mobile station device communicates by connecting to the base station device using cells of a plurality of frequency bands simultaneously,
The plurality of base station devices include a first base station device and a second base station device,
The first base station apparatus transmits a message including specific cell information to the second base station apparatus,
The second base station apparatus is
Identify a combination of cells that can communicate simultaneously with the mobile station apparatus including the specific cell,
A communication system, wherein all or some of the specified combinations of cells are activated. The specific cell information transmitted from the first base station apparatus is:
The communication system according to claim 1, wherein the communication system is selected based on a measurement result from the mobile station apparatus that is communicating in a cell under the control of the first base station apparatus.   The communication system according to claim 1, wherein the specific cell information includes information of a plurality of cells connected to the mobile station device that is communicating with the first base station device.   4. The communication system according to claim 1, wherein the specific cell information includes a cell identifier and / or a cell frequency band. A base station apparatus in a communication system comprising a plurality of base station apparatuses and a mobile station apparatus, wherein the mobile station apparatus is connected to the base station apparatus using a plurality of frequency band cells simultaneously, and performs communication.
The base station device receives specific cell information from another base station device,
Identify a combination of cells that can communicate simultaneously with the mobile station apparatus including the specific cell,
A base station apparatus that activates all or a part of the specified combinations of cells. A base station apparatus in a communication system comprising a plurality of base station apparatuses and a mobile station apparatus, wherein the mobile station apparatus is connected to the base station apparatus using a plurality of frequency band cells simultaneously, and performs communication.
The base station device selects a specific cell based on a measurement result from the mobile station device communicating with the controlled cell,
In order to activate a cell capable of communicating simultaneously with the mobile station apparatus including the specific cell, a message including the specific cell information is notified to a base station apparatus that controls the specific cell. A base station apparatus. A communication method in a communication system comprising a plurality of base station devices and mobile station devices, wherein the mobile station device is connected to the base station device using a plurality of frequency band cells simultaneously to perform communication,
The plurality of base station devices include a first base station device and a second base station device,
The first base station device transmitting a message including specific cell information to the second base station device;
The second base station apparatus is
Identifying a combination of cells capable of communicating simultaneously with the mobile station apparatus including the specific cell;
Activating all or some of the specified combinations of cells.