WO2010143495A1

WO2010143495A1 - Communication system, base station, mobile station, and radio resource allocation method

Info

Publication number: WO2010143495A1
Application number: PCT/JP2010/058128
Authority: WO
Inventors: 克成上村; 恭之加藤
Original assignee: シャープ株式会社
Priority date: 2009-06-10
Filing date: 2010-05-13
Publication date: 2010-12-16

Abstract

Provided are a communication system, a base station, a mobile station, and a radio resource allocation method which enable a reduction in the throughput of decoding processing of a downlink physical channel used for radio resource allocation. Specifically provided is a communication system in which when a mobile station is connected to a base station using a plurality of frequency bands, either the mobile station and/or the base station transmits buffer amount information indicating the amount of untransmitted data to the other, wherein the base station transmits reception control information that orders control after the mobile station acquires the buffer amount information to the mobile station, and the mobile station selects a method of decoding processing of a downlink physical channel used for radio resource allocation on the basis of the reception control information received from the base station and the acquired buffer amount information.

Description

COMMUNICATION SYSTEM, BASE STATION, MOBILE STATION AND RADIO RESOURCE ALLOCATION METHOD

The present invention relates to a communication system in which a mobile station can connect to a base station using a plurality of frequency bands, and more particularly to a base station, a mobile station, and a radio resource allocation method.

Conventionally, in the Evolved Universal Terrestrial Radio Access (hereinafter referred to as EUTRA), when a base station assigns a downlink data channel to a mobile station, a downlink grant composed of information indicating a downlink modulation scheme and a coding scheme. Is transmitted on the downlink shared control channel. Similarly, when allocating an uplink data channel to a mobile station, the base station transmits an uplink grant composed of information indicating an uplink modulation scheme or encoding scheme using a downlink shared control channel (for each channel). Detailed description will be given later).

The uplink grant or downlink grant has a plurality of formats (transmission formats) depending on the control information notified to the mobile station. The uplink grant includes a format for instructing transmission of an uplink data channel using one antenna, a format for instructing transmission of an uplink data channel using a MIMO (Multiple-Input-Multiple-Output) method, and the like. In addition, the downlink grant indicates that the downlink data channel is transmitted using a single transmission antenna or transmission diversity method, and that the number of bits used for radio resource allocation is the same format as that of the uplink grant. There are a format, a format indicating that the downlink data channel is transmitted by the MIMO method, and the like. These formats may be added in the future.

Since the mobile station does not know the format of the downlink shared control channel transmitted from the base station in advance, in order to monitor the uplink grant or the downlink grant, the mobile station receives the received downlink shared control channel. It is necessary to perform a decoding process corresponding to a plurality of formats and identify the type of the transmitted format.

When a mobile station of Advanced EUTRA is connected to a base station using a plurality of different frequency bands (carrier aggregation), it may receive a plurality of downlink shared control channels simultaneously. Therefore, for example, when connected to a base station using two frequency bands, an Advanced EUTRA mobile station requires twice as much decoding processing as an EUTRA mobile station. Therefore, methods for simplifying the amount of decoding processing are proposed in Non-Patent Documents 3 to 4.

In Non-Patent Document 3, the downlink shared control channel is transmitted in two stages, the first downlink shared control channel is transmitted in a fixed format, and the second downlink is transmitted using the first downlink shared control channel. A method for notifying the transmission frequency band and format of the shared control channel has been proposed.

Non-Patent Document 4 proposes a method of transmitting information on whether or not a downlink shared control channel is transmitted in an adjacent frequency band. In addition, a method has been proposed in which information on a frequency band in which the downlink shared control channel is transmitted is transmitted in a predetermined frequency band in advance.

However, since the methods of Non-Patent Documents 3 to 4 need to introduce a new format different from the downlink shared control channel of EUTRA, a large change occurs in both the base station and the mobile station, and the communication system is complicated. become. As a result, there is a problem that the development cost and test cost of the base station and the mobile station increase.

The present invention has been made in view of such circumstances, and when allocating radio resources to a mobile station that can be connected to a base station using a plurality of frequency bands, taking into account the buffer amount, downlink shared control It is an object of the present invention to provide a mobile station, a base station, a communication system, and a radio resource allocation method capable of appropriately controlling the number of frequency bands for receiving channels.

(1) In order to achieve the above object, the present invention has taken the following measures. That is, in the communication system of the present invention, when a mobile station is connected to a base station using a plurality of frequency bands, at least one of the mobile station and the base station is a buffer related to a buffer amount indicating an untransmitted data amount. A communication system for transmitting amount information to the other, wherein the base station transmits reception control information for instructing control after the mobile station acquires the buffer amount information to the mobile station; The mobile station is characterized by selecting a downlink physical channel decoding process method used for radio resource allocation based on the reception control information and the buffer amount information received from the base station.

In this way, the mobile station selects the downlink physical channel decoding processing method used for radio resource allocation based on the reception control information received from the base station and the acquired buffer amount information. The number of control channel decoding processes can be reduced. Thereby, even when the mobile station needs to receive the downlink shared control channel of a plurality of downlink component carriers by carrier aggregation, the processing load when receiving the downlink shared control channel of the mobile station is reduced. be able to. Furthermore, since the processing load on the mobile station is reduced, the mobile station can reduce the processing time, and it is necessary for the time required to receive the downlink data channel and / or to transmit the uplink data channel. Time can be shortened. Further, since the processing load of the mobile station is reduced, the required power consumption can be reduced.

(2) In the communication system of the present invention, the buffer amount is measured during communication by the base station, and the buffer amount information is the entire frequency band of the mobile station connected to the base station using a plurality of frequency bands. This is information indicating the buffer amount of the downlink data, and is transmitted from the base station to the mobile station during communication.

Thus, the buffer amount information is information indicating the buffer amount of the downlink data in the entire frequency band of the mobile station connected to the base station using a plurality of frequency bands. Based on the notified downlink buffer information, the number of downlink component carriers to be received can be limited. Thereby, it is possible to reduce the number of times of decoding of the downlink shared control channel. In addition, since the number of downlink grant formats to be monitored is limited based on the downlink buffer information notified from the base station, the number of downlink shared control channel decoding processes can be reduced.

(3) In the communication system of the present invention, the buffer amount is measured during communication by the base station, and the buffer amount information is obtained for each frequency band of the mobile station connected to the base station using a plurality of frequency bands. This is information indicating the buffer amount of the downlink data, and is transmitted from the base station to the mobile station during communication.

Thus, the buffer amount information is information indicating the buffer amount of the downlink data for each frequency band of the mobile station connected to the base station using a plurality of frequency bands. The downlink shared control channel can be transmitted in a format corresponding to the downlink CC buffer level (downlink buffer level determined for each downlink component carrier) for each carrier. Thereby, the base station can designate the number of times of decoding processing of the downlink shared control channel of the mobile station for each downlink component carrier, and can perform more flexible control.

(4) In the communication system of the present invention, the buffer amount is measured during communication by the base station, and the buffer amount information is connected to the base station using a plurality of frequency bands. Bitmap information indicating whether or not to perform downlink physical channel decoding processing for each frequency band of the station, which is transmitted from the base station to the mobile station during communication.

Thus, the buffer amount information is bitmap information indicating whether or not to perform downlink physical channel decoding processing for each frequency band of a mobile station connected to the base station using a plurality of frequency bands. The mobile station can limit the number of downlink component carriers to be received based on the downlink buffer information notified from the base station. Thereby, it is possible to reduce the number of times of decoding of the downlink shared control channel.

(5) In the communication system of the present invention, the buffer amount is measured during communication by the mobile station, and the buffer amount information is uplink data of the mobile station connected to the base station using a plurality of frequency bands. This is information indicating the buffer amount, and is transmitted from the mobile station to the base station during communication.

Thus, since the buffer amount information is information indicating the buffer amount of uplink data of the mobile station connected to the base station using a plurality of frequency bands, the mobile station includes the measured uplink buffer information. Accordingly, the number of downlink component carriers to be received is limited, and it is possible to reduce the number of times of decoding processing of the downlink shared control channel. In addition, since the number of uplink grant formats to be monitored is limited based on the measured uplink buffer information, the number of downlink shared control channel decoding processes can be reduced.

(6) Further, in the communication system of the present invention, the base station transmits at least one of the buffer amount of the mobile station or the buffer amount of the base station, and the transmission frequency band or transmission format of the downlink physical channel used for radio resource allocation. Information corresponding to at least one of these is transmitted to the mobile station.

In this way, the base station has information corresponding to at least one of the buffer amount of the mobile station or the buffer amount of the base station and at least one of the transmission frequency band or transmission format of the downlink physical channel used for radio resource allocation. In response to this information, the mobile station transmits either the downlink component carrier that receives the downlink shared control channel and the format of the downlink shared control channel that monitors the downlink grant or the uplink grant. Or both, and the decoding process can be performed.

(7) In the communication system of the present invention, the reception control information includes at least one of the buffer amount of the mobile station or the buffer amount of the base station, and the transmission frequency band or transmission of the downlink physical channel used for radio resource allocation. It is a table that is associated with at least one of the formats.

As described above, the reception control information associates at least one of the buffer amount of the mobile station or the buffer amount of the base station with at least one of the transmission frequency band or transmission format of the downlink physical channel used for radio resource allocation. Depending on this information, the mobile station can select either the downlink component carrier that receives the downlink shared control channel and the downlink shared control channel format that monitors the downlink grant or uplink grant according to this information. Alternatively, both can be determined and the decoding process can be performed.

(8) In addition, when the mobile station is connected to the base station using a plurality of frequency bands, the base station of the present invention provides the mobile station with buffer amount information relating to a buffer amount indicating an untransmitted data amount. A base station that transmits the reception control information for instructing control after the mobile station acquires the buffer amount information to the mobile station, and the frequency used by the mobile station for connection Measuring the buffer amount of downlink data for the entire band, transmitting buffer amount information indicating the measured buffer amount to the mobile station, and transmitting the buffer amount of downlink data for the entire frequency band to the mobile station At least of the transmission frequency band or transmission format of the downlink physical channel used for radio resource allocation based on the information and the reception control information corresponding to the buffer amount information It is characterized in that to select a person.

(9) In addition, when the mobile station is connected to the base station using a plurality of frequency bands, the base station of the present invention transmits buffer amount information indicating an untransmitted data amount to the mobile station. A base station that transmits reception control information for instructing control after the mobile station acquires the buffer amount information to the mobile station, and for each frequency band used by the mobile station for connection. Measuring the buffer amount of the downlink data, and transmitting buffer amount information indicating the measured buffer amount to the mobile station, and for the mobile station, the buffer amount information of the downlink data for each frequency band and the Selecting at least one of a transmission frequency band or a transmission format of a downlink physical channel used for radio resource allocation based on reception control information corresponding to the buffer amount information. It is a symptom.

(10) Further, the base station of the present invention, when the mobile station is connected to the base station using a plurality of frequency bands, the buffer amount information regarding the buffer amount indicating the amount of untransmitted data in the mobile station A base station that receives from the mobile station, the mobile station transmits to the mobile station reception control information for instructing control after measuring the buffer amount information, while the mobile station uses for connection Receiving the buffer amount information indicating the buffer amount of the uplink data of the entire frequency band, and receiving the buffer amount information of the uplink data of the entire frequency band and the reception control information corresponding to the buffer amount information to the mobile station And at least one of a transmission frequency band or a transmission format of a downlink physical channel used for radio resource allocation based on That.

(11) Further, in the base station of the present invention, the reception control information includes at least one of a buffer amount of the mobile station or a buffer amount of the base station, and transmission of a downlink physical channel used for radio resource allocation. The table is characterized in that it is a table in which at least one of a frequency band and a transmission format is associated.

(12) In addition, when the mobile station is connected to the base station using a plurality of frequency bands, the mobile station of the present invention provides buffer amount information related to a buffer amount indicating an untransmitted data amount to the base station. And receiving reception control information for instructing control after obtaining the buffer amount information from the base station, and a buffer amount of downlink data for the entire frequency band used for connection Transmission of a downlink physical channel used for radio resource allocation based on buffer amount information of downlink data for the entire frequency band and reception control information corresponding to the buffer amount information. It is characterized in that at least one of a frequency band and a transmission format is selected.

(13) In addition, when the mobile station is connected to the base station using a plurality of frequency bands, the mobile station of the present invention provides buffer amount information regarding a buffer amount indicating an untransmitted data amount to the base station. A mobile station that transmits and receives reception control information instructing control after obtaining the buffer amount information from the base station, and a buffer amount of downlink data for each frequency band used for connection Transmission of the downlink physical channel used for radio resource allocation based on the buffer amount information of the downlink data for each frequency band and the reception control information corresponding to the buffer amount information. It is characterized in that at least one of a frequency band and a transmission format is selected.

(14) In addition, when the mobile station is connected to the base station using a plurality of frequency bands, the mobile station of the present invention transmits buffer amount information related to a buffer amount indicating an untransmitted data amount to the base station. And receiving reception control information for instructing control after obtaining the buffer amount information from the base station, and a buffer amount of uplink data for the entire frequency band used for connection Buffer amount information indicating the measured buffer amount is transmitted to the base station, and the uplink amount buffer amount information of the entire frequency band and the reception control information corresponding to the buffer amount information Based on this, at least one of a transmission frequency band and a transmission format of a downlink physical channel used for radio resource allocation is selected.

(15) In the radio resource allocation method according to the present invention, when a mobile station is connected to a base station using a plurality of frequency bands, an untransmitted data amount of at least one of the mobile station or the base station is determined. A radio resource allocation method based on buffer amount information relating to a buffer amount to be transmitted, wherein the base station transmits reception control information for instructing control after the mobile station acquires the buffer amount information to the mobile station And, in the mobile station, selecting a downlink physical channel decoding process method used for radio resource allocation based on reception control information received from the base station and acquired buffer amount information; It is characterized by including at least.

According to the present invention, the mobile station can appropriately control the number of frequency bands for receiving the downlink shared control channel in consideration of the buffer amount in a state where a plurality of frequency bands are being received. Therefore, the mobile station can reduce the number of times the downlink shared control channel is decoded, and the processing load when receiving the downlink shared control channel can be reduced. In addition, the mobile station can reduce the delay of the decoding process. In addition, the mobile station can reduce power consumption. Also, changes required for the mobile station and the base station can be minimized.

It is a figure which shows an example of the network structure which concerns on embodiment of this invention. In an embodiment of the present invention, it is a figure showing a correspondence relation of a downlink component carrier and an uplink component carrier. It is a block diagram which shows schematic structure of the base station which concerns on embodiment of this invention. It is a block diagram which shows schematic structure of the mobile station which concerns on embodiment of this invention. It is a sequence chart which shows the downlink grant selection reception process in the 1st Embodiment of this invention. In the 1st Embodiment of this invention, it is a figure which shows an example of the downlink buffer amount corresponding | compatible control information notified to a mobile station from a base station. In the 1st Embodiment of this invention, it is a figure which shows another example of the downlink buffer amount corresponding | compatible control information notified to a mobile station from a base station. In the 1st Embodiment of this invention, it is a figure which shows another example of the downlink buffer amount corresponding | compatible control information notified to a mobile station from a base station. In the 1st Embodiment of this invention, it is a flowchart which shows an example of the downlink buffer measurement process of a base station. In the 1st Embodiment of this invention, it is a flowchart which shows an example of the downlink grant selection reception process of a mobile station. It is another sequence chart which shows the downlink grant selection reception process in the 1st Embodiment of this invention. It is a sequence chart which shows the uplink grant selection reception process in the 2nd Embodiment of this invention. In the 2nd Embodiment of this invention, it is a figure which shows an example of the uplink buffer amount corresponding | compatible control information notified to a mobile station from a base station. In the 2nd Embodiment of this invention, it is a figure which shows another example of the uplink buffer amount corresponding | compatible control information notified to a mobile station from a base station. In the 2nd Embodiment of this invention, it is a figure which shows another example of the uplink buffer amount corresponding | compatible control information notified to a mobile station from a base station. In the 2nd Embodiment of this invention, it is a figure which shows an example of the uplink buffer level set information notified to a mobile station from a base station. It is a flowchart which shows an example of the uplink buffer measurement process of the mobile station which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows an example of the uplink grant selection reception process of the mobile station which concerns on the 2nd Embodiment of this invention. It is another sequence chart which shows the uplink grant selection reception process in the 2nd Embodiment of this invention. It is a figure which shows an example which shifts and designates the downlink grant monitoring frequency in the 4th Embodiment of this invention. It is a figure which shows an example which designates by hopping the downlink grant monitoring frequency in the 4th Embodiment of this invention. It is a sequence chart explaining the CC every downlink grant selection reception process in the 5th Embodiment of this invention. In the 5th Embodiment of this invention, it is a figure which shows an example of the downlink CC buffer amount corresponding | compatible control information notified to a mobile station from a base station. In the 5th Embodiment of this invention, it is a flowchart which shows an example of the downlink buffer measurement process for every CC of a base station. In the 5th Embodiment of this invention, it is a flowchart which shows an example of the downlink grant selection reception process for every CC of a mobile station. It is a figure which shows the increase / decrease in the receiving frequency band using a carrier aggregation.

EUTRA, which evolved the 3rd generation mobile communication system in the 3GPP (3rd Generation Partnership Project) standard, which is one of the standards of wireless communication networks, and the advanced EUTRA (also called LTE-Advanced), which is an advanced version, are being studied. It is being advanced.

In Advanced EUTRA, Carrier Aggregation has been proposed as a technology that enables higher-speed data transmission while maintaining compatibility with EUTRA (Non-patent Document 1). Carrier aggregation is a technique for improving a data rate by receiving data transmitted from a plurality of different frequency bands (component carriers) at a receiving device. By introducing carrier aggregation, in addition to the physical layer, each protocol control layer is an intermediate access control (Medium Access Control; MAC) layer, a radio link control (Radio Link Control; RLC) layer, a radio resource control (Radio) Changes occur in the Resource (Control; RRC) layer. The role of the MAC layer is random access, downlink buffer amount measurement / report, uplink timing adjustment, and the like (Non-Patent Document 2).

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

(1) Carrier aggregation FIG. 26 is a diagram illustrating an example of carrier aggregation. The first to third bands respectively indicate downlink frequency bands (component carriers) transmitted by the base station. The transmission bandwidths of the frequency bands of the first band to the third band may be the same, or some or all of them may be different. The first to third bands may be continuous frequency bands or discontinuous frequency bands. The mobile station of this example can receive up to three 20 MHz frequency bands at the same time, and the total reception bandwidth is 60 MHz.

In the example of FIG. 26, the mobile station communicates with the base station using the 20 MHz of the third band at a first time for a certain time, and at the same time, measures the first band to the second band. Is doing. In addition, at a second time, the mobile station adds a second band, and communicates with the base station using a total of 40 MHz of the second band and the third band. The first Band measurement is performed. In addition, at a third time, the mobile station further adds a first band and communicates with the base station using a total of 60 MHz from the first band to the third band. Also, at some other time, in the fourth time, the mobile station has deleted the second band and communicates with the base station using a total of 40 MHz of the first band and the third band. The second band is measured. Thus, by using carrier aggregation, the data rate can be significantly improved without greatly changing the configuration of the base station. The time length from the first time to the fourth time is variable.

When using a communication scheme in which a guard interval (Cyclic Prefix; CP) is provided for each symbol, such as OFDMA (Orthogonal Frequency Division Multiplexing Access), the OFDM symbol timing of each frequency band used for carrier aggregation must be equal. Is desirable. The equal OFDM symbol timing means that the difference in the reception timing of OFDM symbols in each frequency band falls within the CP length at the receiving antenna end of the mobile station. It is also possible to apply the above-described carrier aggregation to the uplink frequency band transmitted by the mobile station. When carrier aggregation is applied to the uplink frequency band, it is desirable that the transmission timing difference in the uplink frequency band is the same or within the length of the CP length.

(2) Physical Channel A physical channel (or physical signal) used in EUTRA and Advanced EUTRA will be described. The physical channel may be added or changed in the future in EUTRA and Advanced EUTRA, but even if it is changed, the description of each embodiment of the present invention is not affected.

Synchronization signal (Synchronization Signal) is used by the mobile station to detect the base station (or relay station device) at high speed. The synchronization signal is composed of three types of primary synchronization signals and secondary synchronization signals in which 31 types of codes are alternately arranged, and 504 cells for identifying a base station by a combination of the primary synchronization signal and the secondary synchronization signal. ID and frame timing for wireless synchronization are shown. The mobile station specifies the cell ID received by the cell search.

The physical broadcast information channel (PBCH) is transmitted for the purpose of reporting control parameters (broadcast information) that are commonly used by mobile stations in the cell. The broadcast information that is not notified on the physical broadcast information channel is transmitted using the downlink data channel with the radio resource notified on the downlink shared control channel. As broadcast information, MBMS information, cell global ID indicating individual cell ID, and the like are notified.

The downlink reference signal is a pilot signal transmitted at a predetermined power for each cell. The downlink reference signal is a signal that is periodically repeated at a predetermined time interval (for example, one frame), and the mobile station receives the downlink reference signal at a predetermined time interval and measures reception quality. Is used to determine reception quality for each cell. Further, it is used as a reference signal for demodulation of the downlink shared control channel or downlink data channel transmitted simultaneously with the downlink reference signal. The sequence used for the downlink reference signal is a sequence that can be uniquely identified for each cell. The downlink reference signal may be described as a cell-specific RS (Cell-specific Reference Signal), but its use and meaning are the same.

The downlink shared control channel (PDCCH; Physical Downlink Common Channel) is transmitted with the number of OFDM symbols at the top of each subframe, and the radio resource allocation information according to the scheduling of the base station and the amount of transmission power adjustment to the mobile station It is a downlink physical channel used for the purpose of instructing. The mobile station receives the downlink shared control channel before transmitting / receiving downlink data (downlink traffic data) and control messages, acquires the uplink grant during transmission, and acquires radio resource allocation information from the downlink grant during reception. There is a need.

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

The random access channel (PRACH; “Physical” Random “Access” Channel) is a channel used to notify the preamble sequence and has a guard time. The random access channel is used as an access procedure to a base station whose uplink transmission timing is asynchronous, and is used for adjusting a radio resource request and uplink transmission timing. Since other physical channels are not related to each embodiment of the present invention, detailed description thereof is omitted. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram illustrating an example of a network configuration according to an embodiment of the present invention. When the mobile station 1 can be connected simultaneously with a plurality of frequency bands (first band to third band) by carrier aggregation, a single base station 3 has a plurality of frequency bands as a network configuration. A configuration in which

transmission devices

11, 12, and 13 (reception devices 21, 22, and 23 (not shown)) are provided for each, and a configuration in which each frequency band is controlled by one base station 3 is preferable from the viewpoint of simplification of control. . Each frequency band controlled by the base station 3 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 widths, that is, different radii.

FIG. 2 is a diagram illustrating an example of a correspondence relationship between a downlink component carrier and an uplink component carrier that are configured when the mobile station 1 of the present invention performs carrier aggregation. The downlink component carrier DL_CC1 corresponds to the uplink component carrier UL_CC1. That is, ACK / NACK of data received by DL_CC1 and reception quality feedback are transmitted by UL_CC1.

Also, it is possible that a plurality of downlink component carriers correspond to the uplink component carrier. In the example shown in the figure, both ACK / NACK of data received by DL_CC2 and DL_CC3 and feedback of reception quality are transmitted by UL_CC2. The mobile station 1 recognizes as a cell without particular awareness of which base station 3 the downlink component carrier is transmitted from and which base station 3 receives the uplink component carrier. Then, information such as the frequency band and bandwidth of the corresponding uplink component carrier is acquired from the broadcast information of the selected cell.

In consideration of the above matters, preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the present invention, detailed descriptions of known functions and configurations related to the present invention will be omitted if it is determined that the gist of the present invention will be obscured.

<First Embodiment>
A first embodiment of the present invention will be described below. The present embodiment relates to a method of receiving a downlink frequency band (downlink component carrier) at the time of carrier aggregation of the mobile station 1, and the downlink received by the mobile station 1 based on the notification of the downlink buffer amount of the base station 3 A method for selecting a link component carrier will be described.

FIG. 3 is a block diagram showing an example of the base station 3 according to the first embodiment of the present invention. The base station 3 includes a reception unit 101, a demodulation unit 103, a decoding unit 105, an upper layer 107, a downlink buffer management unit 109, an encoding unit 111, a modulation unit 113, an RS generation unit 115, a transmission unit 117, a control unit 119, A multiplexing unit 121 is included.

The upper layer 107 inputs downlink data and downlink control data to the encoding unit 111. The downlink buffer management unit 109 stores how much untransmitted data for each connected mobile station 1 stays in a storage device or a buffer (not shown) that is a storage area that temporarily stores downlink data. And the measurement result (downlink buffer information) is input to the encoding unit 111 as necessary. The encoding unit 111 encodes the input data and inputs the encoded data to the modulation unit 113. Modulation section 113 modulates the encoded signal. Further, the signal output from the modulation unit 113 and the downlink reference signal generated by the RS generation unit 115 are mapped to the frequency domain by the multiplexing unit 121. An output signal from the multiplexing unit 121 is input to the transmission unit 117. The transmission unit 117 converts a frequency domain signal into a time domain signal, performs power amplification on a carrier having a predetermined frequency, and transmits the signal.

Also, the receiving unit 101 converts the signal received from the mobile station 1 into a baseband digital signal. The digital signal is input to the demodulator 103 and demodulated. The signal demodulated by the demodulation unit 103 is then input to the decoding unit 105 and decoded, and the correctly decoded uplink control data and uplink data are output to the upper layer 107. The uplink control data includes uplink buffer information reported from the mobile station 1. Control information necessary for controlling each of these blocks is input from the upper layer 107 to the control unit 119, and control information related to transmission from the control unit 119 is transmitted as transmission control information, such as a downlink buffer management unit 109, a coding unit 111, Control information related to reception is appropriately received in each block of the receiver 101, demodulator 103, and decoder 105 as reception control information in each block of the modulator 113, RS generator 115, multiplexer 121, and transmitter 117. Entered. In FIG. 3, the other components of the base station 3 are omitted because they are not related to this embodiment. Note that the downlink buffer management unit 109 may be arranged in a control station higher than the base station 3 and notify the base station 3 of downlink buffer information measured by the higher control station.

FIG. 4 is a block diagram showing an example of the mobile station 1 according to the first embodiment of the present invention. The mobile station 1 includes a reception unit 201, a demodulation unit 203, a decoding unit 205, a measurement processing unit 207, an uplink buffer management unit 209, a random access generation unit 211, an encoding unit 213, a modulation unit 215, a transmission unit 217, a transmission band It comprises a setting unit 219, a control unit 221, and an upper layer 223. Prior to reception, control information is input from the upper layer 223 to the control unit 221, and control information related to reception is appropriately input to the reception unit 201, the demodulation unit 203, and the decoding unit 205 as reception control information. The reception control information includes information such as reception timing, multiplexing method, and radio resource arrangement information regarding each channel in addition to information on the reception frequency band.

The received signal is received by the receiving unit 201. The receiving unit 201 receives a signal in the frequency band specified by the reception control information. The received signal is input to the demodulation unit 203. Demodulation section 203 demodulates the received signal, inputs a signal to decoding section 205 to correctly decode downlink data and downlink control data, and inputs each decoded data to higher layer 223. The downlink control data includes downlink buffer information. The mobile station 1 generates reception control information based on the downlink buffer information, and selects a downlink frequency band for receiving the downlink shared control channel. The received downlink control data is also input to the measurement processing unit 207. The measurement processing unit 207 generates measurement information based on the measurement result of the downlink reference signal reception quality for each cell and the measurement result of the reception error rate of the downlink shared control channel or the downlink data channel. Output to layer 223.

Prior to transmission, control information is input from the upper layer 223 to the control unit 221, and control information related to transmission is transmitted as transmission control information, a random access generation unit 211, an uplink buffer management unit 209, a coding unit 213, and a modulation unit 215. , And input appropriately to the transmission band setting unit 219. 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. The random access information is input to the random access generation unit 211, and random access data is generated. The random access information includes preamble information, radio resource information for transmission, and the like.

The uplink buffer management unit 209 measures how much untransmitted data of the mobile station 1 is retained in a buffer (not shown) that is a storage device or a storage area that temporarily stores uplink data. Then, the measurement result (uplink buffer information) is input to the encoding unit 213 as necessary. In addition to the random access data and the uplink buffer information, the encoding unit 213 receives uplink data and uplink control data from the upper layer 223. The encoding unit 213 appropriately encodes each data according to the transmission control information, and outputs the data to the modulation unit 215. Modulation section 215 modulates the output from encoding section 213. The transmission band setting unit 219 sets a frequency band to be transmitted to each transmission unit 217. The transmitter 217 maps the output of the modulator 215 to the frequency domain, converts the frequency domain signal into a time domain signal, performs power amplification on a predetermined frequency carrier wave, and transmits the signal.

In FIG. 4, the other components of the mobile station 1 are omitted because they are not related to this embodiment. In addition, the correspondence between the network configuration and the frequency band of the communication system in which the base station 3 and the mobile station 1 are arranged can be the same as those shown in FIGS. 1 and 2, respectively.

FIG. 5 is a sequence chart for explaining downlink grant selection reception processing in the first embodiment of the present invention. With reference to FIG. 5, a method will be described in which the mobile station 1 selects a downlink component carrier that receives the downlink shared control channel based on the downlink buffer information. First, the mobile station 1 receives downlink buffer amount corresponding control information from the base station 3 (step S101). The downlink buffer amount corresponding control information includes control information for instructing what kind of control is performed on the downlink buffer information notified from the base station 3.

FIG. 6 is a diagram illustrating an example of downlink buffer amount correspondence control information notified from the base station 3 according to the first embodiment of this invention. As the downlink buffer amount correspondence control information, as shown in FIG. 6, a plurality of downlink buffer amounts (downlink buffer levels 1 to n, n> 1) and the downlink component carrier for monitoring whether or not a downlink grant is transmitted. The set (designated CC set 1 to m, m> 1) is notified. The mobile station 1 acquires the downlink buffer level from the downlink buffer information notified from the base station 3, and determines the downlink component carrier to be received. For example, if the downlink buffer amount is downlink buffer level 3, the downlink component carrier designated by the designated CC set 3 is received, and the downlink grant is monitored.

Also, by classifying the downlink buffer level into two levels and omitting the notification of the designated CC set, monitoring of all received downlink component carriers and designation for each mobile station 1 or cell It is also possible to notify switching of monitoring of one downlink component carrier (also called an anchor carrier).

FIG. 7 is a diagram illustrating another example of the downlink buffer amount corresponding control information notified from the base station 3 according to the first embodiment of this invention. As downlink buffer amount correspondence control information, as shown in FIG. 7, a downlink shared control channel for monitoring a plurality of downlink buffer amounts (downlink buffer levels 1 to n, n> 1) and whether or not a downlink grant is transmitted. (Designated downlink format sets 1 to k, k> 1) are notified. The mobile station 1 acquires the downlink buffer level from the downlink buffer information notified from the base station 3, and determines the format for performing the decoding process. For example, if the downlink buffer amount is downlink buffer level 3, the format of the downlink shared control channel specified by the specified downlink format set 3 is monitored.

FIG. 8 is a diagram illustrating another example of downlink buffer amount corresponding control information notified from the base station 3 according to the first embodiment of this invention. As the downlink buffer amount correspondence control information, as shown in FIG. 8, a plurality of downlink buffer amounts (downlink buffer levels 1 to n, n> 1) and the downlink component carrier monitoring whether or not the downlink grant is transmitted. The set (designated CC set 1 to m, m> 1) and the format of the downlink shared control channel (designated downlink format set 1 to k, k> 1) are notified. The mobile station 1 acquires the downlink buffer level from the downlink buffer information notified from the base station 3, and determines the downlink component carrier to be received and the format for performing the decoding process. For example, if the downlink buffer amount is downlink buffer level 3, the downlink component carrier specified by the designated CC set 3 is received, and the format of the downlink shared control channel designated by the designated downlink format set 3 is changed. Monitor.

6 to 8, the downlink buffer level is the identification data quantized by comparison with one or more threshold values in order to express the number of bits smaller than the number of bits necessary for expressing the actual downlink buffer amount. It is. The downlink buffer level may be expressed by 6 bits so as to have the same number of bits as the method described in EUTRA (3GPP TS36.321). For example, when four downlink component carriers (CC1 to CC4) are assigned, the designated CC set is designated by a combination of {CC1, CC2, CC3} and {CC1, CC3}. The designated downlink format set is designated by a combination of {DF1, DF2} and {DF2} when, for example, three formats (DF1 to DF3) exist in the downlink grant. The base station 3 can also use a bit map format table to notify the downlink component carrier and the designated downlink format set. That is, when CC1 to CC4 are assigned to the mobile station 1 and the combination of {CC1, CC3} is designated, the base station 3 notifies the mobile station 1 of a bitmap table “1010”.

Returning to FIG. 5, the mobile station 1 that has received the downlink buffer amount corresponding control information from the base station 3 holds the received control information. The base station 3 may notify the control information corresponding to the downlink buffer amount using the broadcast information channel, or may individually notify each mobile station 1 using a control message (layer 3 message) during communication.

Also, the base station 3 broadcasts either the correspondence relationship between the downlink buffer level and the designated CC set or the correspondence relationship between the downlink buffer level and the designated downlink format set in the downlink buffer amount correspondence control information. Information may be used for each cell, and the remaining correspondence may be individually notified for each mobile station 1 using a control message (layer 3 message). When notifying each mobile station 1 individually, it is preferable to transmit simultaneously with a control message (layer 3 message) for assigning carrier aggregation.

Subsequently, the base station 3 performs downlink buffer measurement processing, and measures how much downlink data addressed to the mobile station 1 stays in the buffer for each mobile station 1 performing carrier aggregation (step). S102). Then, the base station 3 determines the downlink buffer level from the measured buffer amount of the downlink data, and holds it as downlink buffer information. And downlink buffer information is transmitted to the mobile station 1 as needed (step S103). The downlink buffer information is preferably transmitted using a layer 2 control message (MAC control element) used to notify flow control, quality information indicator, and the like, but a higher control message (layer 3). Message, NAS message) or, for example, a lower control message (L1 message) notified by the downlink shared control channel.

The mobile station 1 acquires the downlink buffer level from the received downlink buffer information. In the downlink grant selection reception process, the mobile station 1 receives the downlink shared control channel based on the downlink buffer amount corresponding control information acquired in advance and the downlink buffer level acquired most recently. Then, one or both of the formats of the downlink shared control channel for monitoring the downlink grant is determined, and the downlink shared control channel is decoded (step S104).

When the base station 3 transmits the downlink buffer level to the mobile station 1 holding the information on the designated CC set, the base station 3 uses the downlink shared control channel on the downlink component carrier of the designated CC set corresponding to the downlink buffer level. Send. Further, when the base station 3 transmits the downlink buffer level to the mobile station 1 holding the information of the downlink format set, the base station 3 transmits the downlink shared control channel in a format corresponding to the downlink buffer level. Then, the base station 3 performs scheduling of the downlink data channel corresponding to the transmitted downlink shared control channel. The mobile station 1 and the base station 3 repeatedly perform the same operations (steps S105 to S107) as the above steps S102 to 104 if carrier aggregation is continuing.

FIG. 9 is a flowchart showing an example of downlink buffer measurement processing of the base station in the first embodiment of the present invention. The downlink buffer measurement process in the base station 3 will be described using the flowchart of FIG. First, the base station 3 measures the downlink buffer amount for each mobile station 1 performing carrier aggregation periodically or whenever downlink radio resources are allocated (before transmission of the downlink grant) (step S201). ). The base station 3 may average the measurement results. Then, it is determined whether or not it is necessary to notify the mobile station 1 of the measured downlink buffer amount as downlink buffer information (step S202). The base station 3 uses, for example, any of the following methods or a combination of several methods as a determination method.
(1) Judged by the elapsed time since the last downlink buffer information was notified. That is, even if there is no change in the downlink buffer amount, notification is periodically made.
(2) It is determined whether or not a predetermined fluctuation has occurred from the downlink buffer amount notified last. That is, it is notified aperiodically when the downlink buffer amount has decreased by a predetermined amount or increased by a predetermined amount since the previous notification.

If the base station 3 determines that transmission of the downlink buffer amount is necessary based on the determination method, the base station 3 compares the downlink buffer amount with at least one threshold (step S203). Then, the base station 3 determines a downlink buffer level for each mobile station 1 in which the measured downlink data buffer amount is expressed by a smaller number of bits based on the comparison with the threshold (step S204). The threshold value used for the comparison may be a value predetermined by the base station 3 or may be notified from a higher control station. The base station 3 completes the processing after performing the above-described processing or when it is determined that there is no need to notify the downlink buffer information to the mobile station 1.

FIG. 10 is a flowchart showing an example of downlink grant selection reception processing of the mobile station in the first embodiment of the present invention. The downlink grant selection reception process in the mobile station 1 will be described using the flowchart of FIG. The mobile station 1 acquires the downlink buffer level from the downlink buffer information notified by the base station 3 (step S301). Subsequently, the received downlink buffer level value is compared with the downlink buffer amount correspondence control information (step S302). Then, the mobile station 1 formats the downlink component carrier that receives the downlink shared control channel and the downlink shared control channel that monitors the downlink grant according to the information notified by the downlink buffer amount corresponding control information. Either or both of these are determined and a decoding process is performed (steps S303 and S304). The mobile station 1 does not receive an unspecified downlink component carrier, and does not monitor a downlink grant of an unspecified format.

FIG. 11 is another sequence chart illustrating downlink grant selection reception processing according to the first embodiment of this invention. In contrast to FIG. 5, as shown in FIG. 11, after the mobile station 1 receives the downlink buffer amount (step S <b> 402), a predetermined effective time timer (effective time timer T <b> 1) is started and the effective time timer T <b> 1 is timed. During this period, the correspondence between the downlink buffer level received from the base station 3 and the designated CC set and / or the correspondence between the downlink buffer level and the designated downlink format set may be validated (step S403). ). The mobile station 1 receives the downlink shared control channels of all assigned downlink component carriers except for the time measured by the valid time timer T1. Alternatively, the mobile station 1 receives the downlink shared control channel of one downlink component carrier (also called an anchor carrier) designated for each mobile station 1 or for each cell except for the time measured by the valid time timer T1.

As described above, the mobile station 1 reduces the number of downlink shared control channel decoding processes because the number of downlink component carriers received based on the downlink buffer information notified from the base station 3 is limited. Is possible. Further, since the number of downlink grant formats monitored based on the downlink buffer information notified from the base station 3 is limited, the number of times of decoding processing of the downlink shared control channel can be reduced.

Therefore, even when the mobile station 1 needs to receive the downlink shared control channel of a plurality of downlink component carriers by carrier aggregation, the processing load when receiving the downlink shared control channel of the mobile station 1 is reduced. Can be reduced. Further, since the processing load of the decoding process is reduced in the mobile station 1, the processing time can be reduced, and the time required until reception of the downlink data channel can be reduced. Further, since the processing load of the mobile station 1 is reduced, it is possible to reduce necessary power consumption.

<Second Embodiment>
A second embodiment of the present invention will be described below. The present embodiment relates to a method of transmitting an uplink frequency band (uplink component carrier) at the time of carrier aggregation of the mobile station 1, and the downlink received by the mobile station 1 based on the measurement of its own uplink buffer amount. A method for selecting a link component carrier will be described.

The mobile station 1 of the second embodiment may be the same as that shown in FIG. The base station 3 may be the same as in FIG. In addition, the correspondence between the network configuration and the frequency band of the communication system in which the base station 3 and the mobile station 1 are arranged can be the same as those shown in FIGS. 1 and 2, respectively.

A method similar to the method described in EUTRA (3GPP TS36.321) is used for the method in which the mobile station 1 measures the uplink buffer amount and reports it to the base station 3. That is, the mobile station 1 compares the uplink buffer amount with a specified threshold value, determines an index value (uplink buffer level) indicating the range of the retained uplink buffer amount, and determines the layer 2 control message (MAC Control element) to the base station 3.

FIG. 12 is a sequence chart illustrating uplink grant selection reception processing in the second embodiment of the present invention. A method for selecting a downlink component carrier from which the mobile station 1 receives the downlink shared control channel based on the uplink buffer information will be described with reference to FIG. First, the mobile station 1 receives uplink buffer amount correspondence control information from the base station 3 (step S501). The control information corresponding to the uplink buffer amount includes control information for instructing what kind of control is to be performed on the uplink buffer information measured by the own station.

FIG. 13 is a diagram illustrating an example of uplink buffer amount correspondence control information notified from the base station 3 according to the second embodiment of this invention. As uplink buffer amount correspondence control information, a plurality of uplink buffer amounts (uplink buffer levels 1 to n, n> 1) and a set of downlink component carriers (designated CC set 1) for monitoring the presence / absence of uplink grant transmission To m, m> 1). The mobile station 1 determines the downlink component carrier received from the uplink buffer level determined based on the measurement. For example, if the uplink buffer amount is the uplink buffer level 3, the downlink component carrier designated by the designated CC set 3 is received, and the uplink grant is monitored.

FIG. 14 is a diagram illustrating another example of uplink buffer amount correspondence control information notified from the base station 3 according to the second embodiment of this invention. As uplink buffer amount correspondence control information, a plurality of uplink buffer amounts (uplink buffer levels 1 to n, n> 1) and a format of a downlink shared control channel for monitoring the presence / absence of uplink grant transmission (designated uplink) Format sets 1 to k, k> 1) are notified. The mobile station 1 determines the format for performing the decoding process from the uplink buffer level determined based on the measurement. For example, if the uplink buffer amount is uplink buffer level 3, the format of the downlink shared control channel designated by the designated uplink format set 3 is monitored.

FIG. 15 is a diagram illustrating another example of the uplink buffer amount correspondence control information notified from the base station 3 according to the second embodiment of this invention. As uplink buffer amount correspondence control information, a plurality of uplink buffer amounts (uplink buffer levels 1 to n, n> 1) and a set of downlink component carriers (designated CC set 1) for monitoring the presence / absence of uplink grant transmission To m, m> 1) and the downlink shared control channel format (designated uplink format sets 1 to k, k> 1). The mobile station 1 determines the downlink component carrier received from the uplink buffer level determined based on the measurement and the format for performing the decoding process. For example, if the uplink buffer amount is uplink buffer level 3, the downlink component carrier designated by the designated CC set 3 is received, and the format of the downlink shared control channel designated by the designated uplink format set 3 is changed. Monitor.

In FIGS. 13 to 15, the uplink buffer level is the identification data quantized by comparison with one or more threshold values in order to express the number of bits smaller than the number of bits necessary for expressing the actual uplink buffer amount. It is. The uplink buffer level may be expressed by 6 bits so as to have the same number of bits as the method described in EUTRA (3GPP TS36.321). For example, when four downlink component carriers (CC1 to CC4) are assigned, the designated CC set is designated by a combination of {CC1, CC2, CC3} and {CC1, CC3}. The designated uplink format set is designated by a combination of {UF1, UF2} and {UF2}, for example, when there are three formats (UF1 to UF3) in the uplink grant. The base station 3 can also use a bit map format table to notify the downlink component carrier and the designated downlink format set. That is, when CC1 to CC4 are assigned to the mobile station 1 and the combination of {CC1, CC3} is designated, the base station 3 notifies the mobile station 1 of a bitmap table “1010”.

FIG. 16 is a diagram illustrating an example of uplink buffer level set information notified from the base station 3 according to the second embodiment of this invention. As shown in FIG. 16, uplink buffer level set information (uplink buffer level sets 1 to t, t> 1) including a plurality of uplink buffer levels is used instead of the uplink buffer information of FIGS. May be.

Returning to FIG. 12, the mobile station 1 that has received the uplink buffer capacity control information from the base station 3 holds the received control information. The base station 3 may notify the control information corresponding to the uplink buffer amount using the broadcast information channel or may individually notify each mobile station 1 using a control message (layer 3 message) during communication. Also, the base station 3 uses the broadcast information to determine either the correspondence relationship between the threshold value and the designated CC set or the correspondence relationship between the threshold value and the designated uplink format set in the uplink buffer amount correspondence control information. May be notified individually using the control message (layer 3 message) for each mobile station 1. When notifying each mobile station 1 individually, it is preferable to transmit simultaneously with a control message (layer 3 message) for assigning carrier aggregation.

Subsequently, the mobile station 1 performs an uplink buffer measurement process, and measures how much uplink data addressed to the base station 3 is retained in the buffer (step S502). Then, the mobile station 1 compares the measured buffer amount of uplink data with a threshold value, determines an uplink buffer level, and holds it as uplink buffer information. Then, uplink buffer information is transmitted to the base station 3 according to the communication status (step S503). The uplink buffer information is preferably transmitted using a layer 2 control message (MAC control element) used to notify flow control, quality information indicator, and the like, but a higher control message (layer 3). Message, NAS message) or, for example, a lower control message (L1 message) notified by the downlink shared control channel.

The mobile station 1 holds the latest uplink buffer level notified to the base station 3 until new uplink buffer information is transmitted. Then, in the uplink grant selection reception process, the mobile station 1 uses the downlink component carrier that receives the downlink shared control channel based on the uplink buffer amount correspondence control information and the uplink buffer level acquired in advance, and the uplink Either or both of the formats of the downlink shared control channel for monitoring the grant are determined, and a decoding process is performed (step S504). When the mobile station 1 holds information on the designated CC set, the mobile station 1 receives the downlink shared control channel on the downlink component carrier of the designated CC set corresponding to the uplink buffer level. Further, when the mobile station 1 holds information on the uplink format set, the mobile station 1 receives the downlink shared control channel in a format corresponding to the uplink buffer level. The mobile station 1 and the base station 3 repeatedly perform the same operations (steps S505 to S507) as the above steps S502 to 504 if the carrier aggregation is continuing.

FIG. 17 is a flowchart illustrating an example of uplink buffer measurement processing in the mobile station 1 according to the second embodiment of this invention. First, the mobile station 1 periodically measures the uplink buffer amount (step S601). The mobile station 1 may average the measurement results. Then, it is determined whether or not it is necessary to notify the measured uplink buffer amount to the base station 3 as uplink buffer information (step S602). If the mobile station 1 determines that transmission of the uplink buffer amount is necessary based on the determination method, the mobile station 1 compares the uplink buffer amount with at least one threshold (step S603), and sets the uplink buffer level. Determination is made (step S604). The method for determining whether to notify the uplink buffer information to the base station 3 and the method for determining the uplink buffer level conform to the specifications of the MAC layer of EUTRA. The mobile station 1 completes the processing after performing the above processing or when it is determined that there is no need to notify the base station 3 of the uplink buffer information.

FIG. 18 is a flowchart illustrating an example of uplink grant selection reception processing in the mobile station 1 according to the second embodiment of this invention. The mobile station 1 acquires the value of the most recent uplink buffer level held (step S701), and compares the uplink buffer level value with the uplink buffer amount corresponding control information (step S702). The mobile station 1 then formats the downlink component carrier that receives the downlink shared control channel and the downlink shared control channel that monitors the uplink grant according to the information notified by the control information corresponding to the uplink buffer amount. Either or both of these are determined and a decoding process is performed (steps S703 and S704). The mobile station 1 does not receive an unspecified downlink component carrier, and does not monitor an uplink grant of an unspecified format. The mobile station 1 may not transmit an uplink reference signal on an uplink component carrier corresponding to an undesignated downlink component carrier.

FIG. 19 is another sequence chart illustrating uplink grant selection reception processing according to the second embodiment of the present invention. In contrast to FIG. 12, as shown in FIG. 19, after the mobile station 1 transmits the uplink buffer amount (step S802), a predetermined valid time timer (valid time timer T2) is started and the valid time timer T2 is counted. During this time, the correspondence between the uplink buffer level transmitted to the base station 3 and the designated CC set and / or the correspondence between the uplink buffer level and the designated downlink format set may be validated (step S803). ). The mobile station 1 receives the downlink shared control channel of all assigned downlink component carriers except for the time measured by the valid time timer T2. Alternatively, the mobile station 1 receives a downlink shared control channel of one downlink component carrier (also called an anchor carrier) designated for each mobile station 1 or for each cell except for the time measured by the valid time timer T2.

As described above, since the number of downlink component carriers to be received is limited based on the measured uplink buffer information, the mobile station 1 can reduce the number of downlink shared control channel decoding processes. In addition, since the number of uplink grant formats to be monitored is limited based on the measured uplink buffer information, the number of downlink shared control channel decoding processes can be reduced.

Therefore, even when the mobile station 1 needs to receive the downlink shared control channel of a plurality of downlink component carriers by carrier aggregation, the processing load when receiving the downlink shared control channel of the mobile station 1 is reduced. Can be reduced. Furthermore, since the processing load of the decoding process is reduced in the mobile station 1, the processing time can be reduced, and the time required until transmission of the uplink data channel can be reduced. Further, since the processing load of the mobile station 1 is reduced, it is possible to reduce necessary power consumption.

<Third Embodiment>
In the first embodiment and the second embodiment, the processing load of either the downlink grant or the uplink grant is reduced. Therefore, in the third embodiment, a method for reducing the decoding process for both the downlink grant and the uplink grant will be described.

The base station 3 transmits downlink buffer amount correspondence control information, uplink buffer amount correspondence control information, and downlink buffer information to the mobile station 1, and the mobile station 1 measures the uplink buffer information and sends it to the base station 3. Send. These pieces of information are the same as those described in the first embodiment and the second embodiment.

As described above, the mobile station 1 can reduce the number of times of the downlink shared control channel decoding process based on the downlink buffer information and the uplink buffer information, and the first embodiment and the second embodiment. The effect of the form can be obtained at the same time.

<Fourth Embodiment>
In the embodiments so far, the downlink component carrier on which the mobile station 1 receives the downlink shared control channel is information that is fixedly specified, and the received downlink component carrier cannot be changed. However, if the downlink component carrier received by the mobile station 1 can be received while being periodically changed, there is an advantage from the viewpoint of the frequency diversity effect.

Therefore, in the fourth embodiment, a method is described in which the mobile station 1 can receive at different frequencies while limiting the number of downlink component carriers that receive the downlink shared control channel.

FIG. 20 is a diagram illustrating an example in which the downlink grant monitoring frequency is shifted and specified in the fourth embodiment of the present invention. CC1 to CC4 in FIG. 20 indicate downlink component carriers allocated to the mobile station 1, and are connected to the base station 3 using a maximum of four frequency bands. At this time, the base station 3 notifies the mobile station 1 of the number of received CCs (the number of downlink grant monitoring frequency bands) instead of the designated CC set corresponding to each downlink buffer level. In this example, the number of received CCs is a value from 1 to 4.

The base station 3 notifies the reception CC pattern, the CC shift amount, and the reception initial CC position as necessary in order to uniquely specify the downlink component carrier received by the mobile station 1.

The received CC pattern indicates which downlink component carrier is received when the number of received CCs is smaller than the number of assigned downlink component carriers. The reception CC pattern can be specified by a bitmap, for example. The CC shift amount indicates the shift amount when the downlink component carrier received every certain cycle time is shifted and received. The reception initial CC position indicates the start position of the downlink component carrier received first when the CC shift amount is designated. Some of these pieces of information can be obtained from the base station 3 if the mobile station 1 knows in advance because the value is fixedly set or is calculated from the frame number (subframe number). It is also possible to omit the notification.

In the example of FIG. 20, the downlink grant monitoring frequency bands of the downlink buffer level 2 are CC1 and CC2 at time T10, and shifted CC2 and CC3 are received at time T11 after the cycle time Th1. ing.

FIG. 21 is a diagram illustrating an example of hopping and specifying a downlink grant monitoring frequency according to the fourth embodiment of the present invention. As shown in FIG. 21, the downlink component carrier may be received by hopping. In this case, hopping pattern information is additionally notified from the base station 3. Although FIG. 20 and FIG. 21 have described the reception of the downlink grant, the same method can be easily applied to the uplink grant, and details thereof are omitted.

As described above, the base station 3 can change the downlink component carrier received by the mobile station 1 while reducing the number of times of decoding of the downlink shared control channel of the mobile station 1. As a result, since the mobile station 1 can obtain the frequency diversity effect, the detection performance of the downlink grant or the uplink grant is improved, and the communication quality is improved.

<Fifth Embodiment>
In the embodiments described so far, the base station 3 measures the downlink buffer amount of the entire downlink component carrier to which the mobile station 1 performing carrier aggregation is connected.

In the fifth embodiment, a method will be described in which base station 3 measures and notifies the downlink buffer amount for each downlink component carrier, thereby enabling more flexible control. Here, the downlink buffer amount measured for each downlink component carrier is referred to as downlink CC buffer information.

FIG. 22 is a sequence chart for explaining the per-CC downlink grant selection reception process in the fifth embodiment of the present invention. A method for selecting a downlink component carrier from which the mobile station 1 receives the downlink shared control channel based on the downlink CC buffer information will be described with reference to FIG. First, the mobile station 1 receives downlink CC buffer amount corresponding control information from the base station 3 (step S901). The downlink CC buffer amount corresponding control information includes control information for instructing what kind of control is performed on the downlink CC buffer information notified from the base station 3.

FIG. 23 is a diagram illustrating an example of downlink CC buffer amount control information notified from the base station 3 according to the fifth embodiment of the present invention. As the downlink CC buffer amount corresponding control information, the downlink CC buffer amount (downlink CC buffer level 1 to n, n> 1) and the downlink shared control channel format (designated downlink format set 1 to k, k>) 1) is notified. The mobile station 1 acquires the downlink CC buffer level from the downlink CC buffer information notified from the base station 3, and determines the format for performing the decoding process for each downlink component carrier.

For example, in the downlink component carrier whose downlink CC buffer amount is the downlink CC buffer level 2, the format of the downlink shared control channel specified in the specified downlink format set 2 is monitored. By not setting the format information in the designated downlink format set corresponding to a certain downlink CC buffer level, it is possible to indicate that it is not necessary to monitor the downlink component carrier. Further, by classifying the downlink CC buffer level into two levels, it is also possible to indicate whether or not to monitor the downlink component carrier. In this case, the base station 3 does not have to notify the mobile station 1 of the downlink CC buffer amount correspondence control information. Alternatively, a threshold value for classifying the downlink CC buffer level into two levels may be notified instead.

In FIG. 23, the downlink CC buffer level is the identification data quantized by comparison with one or more threshold values in order to express the number of bits smaller than the number of bits necessary for expressing the actual downlink CC buffer amount. It is. The downlink CC buffer level may be expressed by 6 bits so as to have the same number of bits as the method described in EUTRA (3GPP TS36.321).

Referring back to FIG. 22, the mobile station 1 that has received the downlink CC buffer amount control information from the base station 3 holds the received control information. The base station 3 may notify the downlink CC buffer amount corresponding control information through the broadcast information channel, or may individually notify each mobile station 1 using a control message (layer 3 message) during communication. If the downlink CC buffer amount correspondence control information is uniquely determined in the system, the transmission / reception processing of the downlink CC buffer amount correspondence control information in FIG. 22 can be omitted.

Subsequently, the base station 3 measures how much downlink data for each downlink component carrier addressed to the mobile station 1 stays in the buffer for each mobile station 1 performing carrier aggregation (step S902). ). Then, the base station 3 determines a downlink buffer level (downlink CC buffer level) for each downlink component carrier from the measured buffer amount of downlink data for each downlink component carrier, and holds it as downlink CC buffer information. To do. Alternatively, after measuring the downlink buffer amount of the entire downlink component carrier, the base station 3 distributes the downlink data retained in the buffer to the downlink component carrier, and uses the allocated buffer amount as the downlink CC buffer. Amount. Then, a downlink CC buffer level corresponding to the downlink CC buffer amount is determined and held as downlink CC buffer information.

Then, the downlink CC buffer information is transmitted to the mobile station 1 as necessary (step S903). The downlink CC buffer information is preferably transmitted using a layer 2 control message (MAC control element), but a higher level control message (layer 3 message, NAS message) or, for example, a downlink shared control channel It may be transmitted in a lower control message (L1 message) notified in

The mobile station 1 acquires the downlink CC buffer level from the received downlink CC buffer information. In the per-CC downlink grant selection reception process, the mobile station 1 monitors the downlink grant for each downlink component carrier based on the downlink CC buffer amount correspondence control information and the downlink CC buffer level acquired in advance. The format of the downlink shared control channel is determined, and decoding processing is performed (step S904). When the base station 3 transmits the downlink CC buffer level to the mobile station 1 holding the information of the downlink format set, the base station 3 shares the downlink in a format corresponding to the downlink CC buffer level for each downlink component carrier. Send control channel. Then, the base station 3 performs scheduling of the downlink data channel corresponding to the transmitted downlink shared control channel. The mobile station 1 and the base station 3 repeatedly perform the same operations (steps S905 to S907) as the above steps S902 to 904 if the carrier aggregation is continuing.

FIG. 24 is a flowchart illustrating an example of the per-CC downlink buffer measurement process in the base station 3 according to the fifth embodiment of the present invention. First, the base station 3 measures the downlink CC buffer amount for each mobile station 1 performing carrier aggregation periodically or every time a downlink radio resource is allocated (before transmission of a downlink grant) (step). S1001). The base station 3 may average the measurement results.

Then, it is determined whether or not the measured downlink CC buffer amount needs to be notified to the mobile station 1 as downlink CC buffer information (step S1002). The base station 3 uses, for example, any of the following methods or a combination of several methods as a determination method.
(1) Judged by the elapsed time since the last downlink CC buffer information was notified. That is, even if there is no change in the downlink CC buffer amount, it is periodically notified.
(2) It is determined whether a predetermined fluctuation has occurred from the downlink CC buffer amount notified last. That is, it is notified aperiodically when the downlink CC buffer amount has decreased by a predetermined amount or increased by a predetermined amount since the previous notification.

If the base station 3 determines that transmission of the downlink CC buffer amount is necessary based on the determination method, the base station 3 compares the downlink CC buffer amount with at least one threshold (step S1003). Then, the base station 3 determines the downlink CC buffer level for each mobile station 1 that represents the buffer amount of the downlink data for each downlink component carrier measured with a smaller number of bits based on the comparison with the threshold ( Step S1004). The threshold value used for the comparison may be a value predetermined by the base station 3 or may be notified from a higher control station. The base station 3 completes the processing after performing the above-described processing or when it is determined that there is no need to notify the downlink CC buffer information to the mobile station 1.

Also, when the downlink CC buffer level is classified into two levels, the base station 3 can also use a bit map format table in which the downlink CC buffer levels are combined into one. That is, when CC1 to CC4 are allocated to the mobile station 1 and the monitoring of CC1 and CC3 is specified, the base station notifies the mobile station 1 of a bitmap table “1010”. Further, this table can be transmitted by one downlink component carrier (also called an anchor carrier) designated for each mobile station 1 or for each cell.

FIG. 25 is a flowchart illustrating an example of a per-CC downlink grant selection reception process in the mobile station 1 according to the fifth embodiment of the present invention. The mobile station 1 acquires the downlink CC buffer level from the downlink CC buffer information notified by the base station 3 (step S1101). Subsequently, the received downlink CC buffer level value is compared with the downlink CC buffer amount correspondence control information (step S1102). Then, the mobile station 1 determines the downlink component carrier that receives the downlink shared control channel and the downlink shared control channel that monitors the downlink grant according to the information notified by the downlink CC buffer amount corresponding control information. Either or both of the formats are determined, and decoding processing is performed (steps S1103 and S1104). The mobile station 1 does not receive the downlink component carrier notified that the monitoring is unnecessary, and does not monitor the downlink grant of the unspecified format.

Also, the valid time timer shown in FIG. 11 in this embodiment can be applied to each downlink component carrier. At this time, the timer applied to the downlink component carrier may be changed according to the downlink CC buffer level.

As described above, the base station 3 can designate the number of decoding processes of the downlink shared control channel of the mobile station 1 for each downlink component carrier, and can perform more flexible control. .

In the embodiment described above, the function of each unit of the mobile station 1 and the base station 3 or a program for realizing a part of these functions is recorded on a computer-readable recording medium and recorded on this recording medium. The mobile station 1 and the base station 3 may be controlled by causing the computer system to read and execute the program. Here, the “computer system” includes an OS and hardware such as peripheral devices.

Further, the “computer-readable recording medium” means a storage device such as a flexible disk, 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.

Further, 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 be used.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design and the like within the scope of the present invention are also within the scope of the claims. include.

DESCRIPTION OF SYMBOLS 1 Mobile station 3 Base station 11 1st transmitter 12 Second transmitter 13 Third transmitter 101 Receiver 103 Demodulator 105 Decoder 107 Upper layer 109 Downlink buffer manager 111 Encoder 113 Modulator 115 RS Generation unit 117 Transmission unit 119 Control unit 121 Multiplexing unit 201 Reception unit 203 Demodulation unit 205 Decoding unit 207 Measurement processing unit 209 Uplink buffer management unit 211 Random access generation unit 213 Encoding unit 215 Modulation unit 217 Transmission unit 219 Transmission band setting unit 221 Control unit 223 Upper layer

Claims

When a mobile station is connected to a base station using a plurality of frequency bands, at least one of the mobile station or the base station transmits buffer amount information related to a buffer amount indicating an untransmitted data amount to the other A communication system,
The base station transmits reception control information instructing control after the mobile station acquires the buffer amount information to the mobile station,
The communication system, wherein the mobile station selects a downlink physical channel decoding method used for radio resource allocation based on reception control information and the buffer amount information received from the base station.
The buffer amount is measured during communication by the base station, and the buffer amount information is a buffer amount of downlink data in the entire frequency band of the mobile station connected to the base station using a plurality of frequency bands. The communication system according to claim 1, wherein the communication information is transmitted from the base station to the mobile station during communication.
The buffer amount is measured during communication by the base station, and the buffer amount information is a buffer amount of downlink data for each frequency band of the mobile station connected to the base station using a plurality of frequency bands. The communication system according to claim 1, wherein the communication information is transmitted from the base station to the mobile station during communication.
The buffer amount is measured during communication by the base station, and the buffer amount information is obtained by decoding a downlink physical channel for each frequency band of the mobile station connected to the base station using a plurality of frequency bands. 2. The communication system according to claim 1, wherein bitmap information indicating whether or not processing is performed is transmitted from the base station to the mobile station during communication.
The buffer amount is measured during communication by the mobile station, and the buffer amount information is information indicating the buffer amount of uplink data of the mobile station connected to the base station using a plurality of frequency bands. The communication system according to claim 1, wherein the communication is transmitted from the mobile station to the base station during communication.
The base station has information corresponding to at least one of a buffer amount of the mobile station or a buffer amount of the base station and at least one of a transmission frequency band or a transmission format of a downlink physical channel used for the radio resource allocation. The communication system according to claim 4, wherein: is transmitted to the mobile station.
The reception control information associates at least one of the buffer amount of the mobile station or the buffer amount of the base station with at least one of the transmission frequency band or transmission format of the downlink physical channel used for the radio resource allocation. The communication system according to claim 1, wherein the communication system is a table.
When a mobile station is connected to a base station using a plurality of frequency bands, the base station transmits buffer amount information related to a buffer amount indicating an untransmitted data amount to the mobile station,
The mobile station transmits reception control information for instructing control after obtaining the buffer amount information to the mobile station, and the buffer amount of downlink data for the entire frequency band used by the mobile station for connection And transmitting buffer amount information indicating the measured buffer amount to the mobile station,
A transmission frequency band of a downlink physical channel used for radio resource allocation to the mobile station based on buffer amount information of downlink data of the entire frequency band and reception control information corresponding to the buffer amount information Alternatively, a base station that causes at least one of transmission formats to be selected.
When a mobile station is connected to a base station using a plurality of frequency bands, the base station transmits buffer amount information related to a buffer amount indicating an untransmitted data amount to the mobile station,
The mobile station transmits reception control information for instructing control after obtaining the buffer amount information to the mobile station, and the buffer amount of downlink data for each frequency band used by the mobile station for connection And transmitting buffer amount information indicating the measured buffer amount to the mobile station,
Transmission frequency band of downlink physical channel used for radio resource allocation based on buffer amount information of downlink data for each frequency band and reception control information corresponding to the buffer amount information for the mobile station Alternatively, a base station that causes at least one of transmission formats to be selected.
When a mobile station is connected to a base station using a plurality of frequency bands, the mobile station is a base station that receives buffer amount information related to a buffer amount indicating an untransmitted data amount in the mobile station from the mobile station,
While the mobile station transmits reception control information for instructing control after measuring the buffer amount information to the mobile station, the buffer amount of uplink data of the entire frequency band used by the mobile station for connection Receive buffer amount information indicating
The transmission frequency band of the downlink physical channel used for radio resource allocation to the mobile station based on the buffer amount information of the uplink data of the entire frequency band and the reception control information corresponding to the buffer amount information Alternatively, a base station that causes at least one of transmission formats to be selected.
The reception control information associates at least one of the buffer amount of the mobile station or the buffer amount of the base station with at least one of the transmission frequency band or transmission format of the downlink physical channel used for the radio resource allocation. 9. The base station according to claim 8, wherein the base station is a table.
When a mobile station is connected to a base station using a plurality of frequency bands, the mobile station transmits buffer amount information regarding a buffer amount indicating an untransmitted data amount to the base station,
From the base station, receiving reception control information for instructing control after obtaining the buffer amount information, and receiving buffer amount information indicating the buffer amount of downlink data for the entire frequency band used for connection,
Based on buffer amount information of downlink data for the entire frequency band and reception control information corresponding to the buffer amount information, at least one of a transmission frequency band or a transmission format of a downlink physical channel used for radio resource allocation is determined. A mobile station characterized by being selected.
When a mobile station is connected to a base station using a plurality of frequency bands, the mobile station transmits buffer amount information regarding a buffer amount indicating an untransmitted data amount to the base station,
From the base station, receiving reception control information for instructing control after obtaining the buffer amount information, receiving buffer amount information indicating a buffer amount of downlink data for each frequency band used for connection,
Based on the downlink data buffer amount information for each frequency band and the reception control information corresponding to the buffer amount information, at least one of the transmission frequency band or transmission format of the downlink physical channel used for radio resource allocation is determined. A mobile station characterized by being selected.
When a mobile station is connected to a base station using a plurality of frequency bands, the mobile station transmits buffer amount information regarding a buffer amount indicating an untransmitted data amount to the base station,
The reception control information for instructing control after obtaining the buffer amount information is received from the base station, and the buffer amount of uplink data in the entire frequency band used for connection is measured, and the measured buffer amount The buffer amount information indicating is transmitted to the base station,
At least one of the transmission frequency band or transmission format of the downlink physical channel used for radio resource allocation based on the buffer amount information of the uplink data of the entire frequency band and the reception control information corresponding to the buffer amount information A mobile station characterized by selecting.
When a mobile station is connected to a base station using a plurality of frequency bands, a radio resource allocation method based on buffer amount information relating to a buffer amount indicating an untransmitted data amount of at least one of the mobile station or the base station There,
In the base station, the mobile station transmits reception control information for instructing control after the mobile station acquires the buffer amount information to the mobile station;
The mobile station includes at least a step of selecting a downlink physical channel decoding process method used for radio resource allocation based on the reception control information and the buffer amount information received from the base station. A radio resource allocation method.