JP5692427B2 - Wireless communication method and wireless communication apparatus - Google Patents

Description

The present invention relates to a wireless communication method and a wireless communication apparatus .

  Currently, wireless communication systems such as mobile phone systems and wireless MAN (Metropolitan Area Network) are widely used. Further, in the field of wireless communication, active discussions are continuously being made on next-generation communication technology in order to further improve communication speed and communication capacity.

  In wireless communication, one wireless communication device may transmit a control signal to the other wireless communication device. The information transmitted as the control signal includes information referred to by the counterpart device to receive the data transmitted by the own device (for example, information indicating the radio resource used for data transmission and the modulation and coding scheme). obtain. Also, information referred to when the counterpart device transmits data to the own device (for example, information specifying a radio resource to be used for data transmission or a modulation and coding scheme) may be included.

  Here, for example, in a radio communication system such as an LTE (Long Term Evolution) system or an LTE-A (LTE-Advanced) system, a radio resource region (search space) in which a radio communication device on the receiving side should monitor the presence or absence of a control signal. ) In each radio subframe of the radio downlink. The search space includes a common search space for a control signal commonly referred to by a plurality of wireless communication apparatuses and a UE-specific (User Equipment-specific) search space for a control signal referred to by a specific wireless communication apparatus. is there. The transmitting-side radio communication apparatus transmits a control signal using radio resources in the search space corresponding to the destination of the control signal. The radio communication device on the receiving side monitors the UE search space corresponding to the common search space and its own device, and detects the control signal. By defining such a search space, the area to be monitored by each wireless communication device can be limited, and the amount of signal processing required to detect a control signal for the device itself can be reduced.

  For example, in the LTE system, the position of the UE individual search space is made variable according to the identifier of the radio communication device on the receiving side and the subframe (time unit for performing radio signal transmission scheduling) (for example, non-patent document). 1 section 9.1.1). In this case, the radio communication devices on the transmission side and the reception side can each calculate the position of the UE individual search space based on a predetermined algorithm. In wireless communication, a constant amount of control signal is not always transmitted. Therefore, in order to effectively use radio resources, a plurality of search spaces may be set so that overlapping areas occur.

  Further, for example, in the LTE-A system, it has been studied to enable wireless communication using a plurality of frequency bands in parallel. Each of the plurality of frequency bands may be referred to as a component carrier. In addition, when a plurality of frequency bands are used, it has been studied to enable transmission of control signals and corresponding data in different frequency bands. Such a control signal transmission method is sometimes called cross-carrier scheduling. In cross carrier scheduling, it is also possible to transmit control signals for a plurality of frequency bands in one frequency band (see, for example, Non-Patent Documents 2 and 3).

3rd Generation Partnership Project, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures", 3GPP TS 36.213 V9.0.1, 2009-12. 3rd Generation Partnership Project, "PDCCH monitoring set", R1-094571, 3GPP TSG RAN WG1 Meeting # 59, 2009-11. 3rd Generation Partnership Project, "Considerations on issues of UE Component Carrier set", R1-094676, 3GPP TSG RAN WG1 Meeting # 59, 2009-11.

  Here, if the control signal is transmitted using a frequency band that is smaller than the frequency band in which data communication is performed, the amount of control signal to be transmitted included in one search space increases. On the other hand, as described above, an overlap may occur between a plurality of search spaces. Therefore, depending on the usage status of other search spaces, the radio resources that can be used substantially decrease, and it may occur that sufficient radio resources corresponding to the control signal to be transmitted cannot be secured.

The present invention has been made in view of the above points, and a radio communication method and a radio communication apparatus that facilitate securing radio resources used for transmission of control signals when communication is performed using a plurality of frequency bands. The purpose is to provide.

  In order to solve the above-described problem, according to one aspect, a wireless communication method in a wireless communication apparatus that communicates with another wireless communication apparatus using a plurality of component carriers is provided. The radio communication method sets a radio resource area in which another radio communication apparatus searches for a control signal based on information on the use of a plurality of component carriers, and within the set radio resource area, A control signal addressed to the communication device is transmitted.

According to the radio communication method, it is easy to secure radio resources used for transmission of control signals when communication is performed using a plurality of frequency bands.
The above and other objects, features and advantages of the present invention will become apparent from the following description in conjunction with the accompanying drawings which illustrate preferred embodiments as examples of the present invention.

It is a figure which shows the radio | wireless communications system of 1st Embodiment. It is a figure which shows the mobile communication system of 2nd Embodiment. It is a figure which shows the example of a setting of a component carrier. It is a figure which shows the structural example of a radio | wireless frame. It is a figure which shows the example of transmission of PDCCH. It is a figure which shows the example of the transmission area | region of PDCCH. It is a block diagram which shows the structure of a base station. It is a block diagram which shows the structure of a mobile station. It is a flowchart which shows transmission / reception of PDCCH of 2nd Embodiment. It is a figure which shows the example of a setting of the search space of 2nd Embodiment. It is a flowchart which shows transmission / reception of PDCCH of 3rd Embodiment. It is a figure which shows the example of a setting of the search space of 3rd Embodiment. It is a flowchart which shows transmission / reception of PDCCH of 4th Embodiment. It is a figure which shows the example of a setting of the search space of 4th Embodiment. It is a flowchart which shows transmission / reception of PDCCH of 5th Embodiment. It is a figure which shows the example of a setting of the search space of 5th Embodiment.

Hereinafter, the present embodiment will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram illustrating a wireless communication system according to the first embodiment. The wireless communication system according to the first embodiment includes wireless communication devices 10 and 20. For example, it is conceivable to realize the wireless communication device 10 as a base station or a relay station and the wireless communication device 20 as a mobile station. The wireless communication devices 10 and 20 perform wireless communication using a plurality of frequency bands. The wireless communication device 10 transmits a control signal to the wireless communication device 20 in at least one of a plurality of frequency bands.

  The wireless communication device 10 includes a control unit 11 and a transmission unit 12. The control unit 11 sets a radio resource area (search area) in which the radio communication device 20 searches for a control signal based on information on the use of a plurality of frequency bands. The transmission unit 12 transmits a control signal addressed to the wireless communication device 20 within the search area set by the control unit 11.

  The information about the use of a plurality of frequency bands may include information indicating the number of frequency bands that the wireless communication device 20 uses for data communication. For example, the control unit 11 changes the size or position of the search area based on the number of frequency bands. The information on the use of a plurality of frequency bands may include information indicating the frequency band in which the search area is set. For example, the control unit 11 changes the size or position of the search region depending on which frequency band is set as the search region. For example, the position and size of the search area may be determined by inputting numerical values such as the number and number of frequency bands into a predetermined function.

  In addition to the information about the use of a plurality of frequency bands, the control unit 11 further refers to the timing information for transmitting the control signal (for example, the subframe number) and the identification information of the wireless communication device 20 to search region May be set. In this case, for example, the position and size of the search area can be determined by inputting numerical values such as the number and number of frequency bands, the subframe number, and the identification number of the wireless communication device 20 into a predetermined hash function. Conceivable.

  The wireless communication device 20 includes a calculation unit 21 and a detection unit 22. The calculation unit 21 calculates a search region used for transmission of a control signal addressed to the own apparatus based on information on the use of a plurality of frequency bands. The search area calculation method in the calculation section 21 corresponds to the search area setting method in the control section 11. The detection unit 22 detects a control signal addressed to its own device by processing (for example, blind decoding) a signal within the search area calculated by the calculation unit 21 among the signals received from the wireless communication device 10.

  The algorithm for determining the size and position of the search area may be fixedly determined in advance. In that case, the control unit 11 and the calculation unit 21 can independently calculate a search area according to a predetermined algorithm. Further, the radio communication device 10 and the radio communication device 20 may select an algorithm for determining the size and position of the search area by signaling. In that case, it is possible to select an appropriate algorithm according to the communication environment.

  In such a wireless communication system according to the first embodiment, the wireless communication device 10 sets a search area in which the wireless communication device 20 searches for a control signal based on information about the use of a plurality of frequency bands. Then, a control signal addressed to the wireless communication device 20 is transmitted within the set search area. The wireless communication device 20 calculates a set search area based on information about the use of a plurality of frequency bands. And the signal in the calculated search area is processed among the signals received from the radio | wireless communication apparatus 10, and the control signal addressed to an own apparatus is detected.

  Thereby, the radio resources that overlap efficiently between the search area of the radio communication device 20 and another search area (for example, a search area common to a plurality of radio communication apparatuses or a search area of other radio communication apparatuses). It is possible to reduce the amount of. Therefore, even when the amount of control signal to be transmitted increases by performing communication using a plurality of frequency bands, radio resources used for transmission of the control signal can be easily secured.

  For example, it is conceivable to increase the search area as the number of frequency bands used for data communication increases. It is also conceivable to increase the search area as the difference between the frequency band used for data communication and the number of frequency bands used for control signal transmission increases. According to this method, it is possible to achieve a balance between the increase in the search burden of the wireless communication device 20 by increasing the search area and the ease of securing radio resources. In addition, when transmitting a control signal using a plurality of frequency bands, it is conceivable to change the position of the search area depending on the frequency band. According to this method, even if sufficient radio resources cannot be secured in one frequency band, there is a high possibility that sufficient radio resources can be secured in other frequency bands.

  In the second to fifth embodiments described below, a case is considered in which the radio communication system of the first embodiment is realized as an LTE-A mobile communication system. However, the wireless communication system according to the first embodiment can of course be realized as a fixed wireless communication system or other types of mobile communication systems.

[Second Embodiment]
FIG. 2 is a diagram illustrating the mobile communication system according to the second embodiment. The mobile communication system according to the second embodiment includes a base station 100 and mobile stations 200 and 200a.

  The base station 100 is a wireless communication device that performs wireless communication with the mobile stations 200 and 200a. The base station 100 is connected to a wired upper network (not shown), and transfers data between the upper network and the mobile stations 200 and 200a. As will be described later, the base station 100 can use a plurality of (for example, five) frequency bands called component carriers (CC) for wireless communication.

  The mobile stations 200 and 200a are wireless terminal devices that connect to the base station 100 and perform wireless communication, and are mobile phones and portable information terminal devices, for example. The mobile stations 200 and 200a receive data from the base station 100 and transmit data to the base station 100. A link from the base station 100 to the mobile stations 200 and 200a may be referred to as a downlink (DL: DownLink), and a link from the mobile stations 200 and 200a to the base station 100 may be referred to as an uplink (UL: UpLink). The mobile stations 200 and 200a use some or all of the plurality of CCs. Communication using two or more CCs in parallel may be referred to as carrier aggregation.

  The base station 100 can be considered as an example of the wireless communication apparatus 10 according to the first embodiment, and the mobile stations 200 and 200a can be considered as an example of the wireless communication apparatus 20 according to the first embodiment. In the second embodiment, the case where the mobile stations 200 and 200a are connected to the base station is considered. However, the mobile stations 200 and 200a may be connected to the relay station. In that case, transmission / reception of a control signal to be described later is performed between the relay station and the mobile stations 200 and 200a.

FIG. 3 is a diagram illustrating a setting example of component carriers. The base station 100 can use a maximum of five CCs (CC # 1 to CC # 5) for communication with the mobile stations 200 and 200a.
When frequency division duplex (FDD) is used for bidirectional communication, the frequency bands of CC # 1 to CC # 5 are secured for each of DL and UL. When simply referred to as CC, it may refer to a set of a frequency band for DL and a frequency band for UL. When using time division duplex (TDD) for bidirectional communication, five frequency bands are secured without distinguishing between DL and UL. FIG. 3 shows a case where FDD is used.

  Base station 100 sets the bandwidths of CCs # 1 to # 5 in consideration of the number of mobile stations scheduled to be accommodated and the required communication speed. For example, the bandwidths of CC # 1 to CC # 5 are selected from 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz. All CCs may have the same bandwidth or different bandwidths depending on the CC. Base station 100 performs radio resource allocation management for CCs # 1 to # 5.

  FIG. 4 is a diagram illustrating a structure example of a radio frame. In each of CC # 1 to CC # 5, a radio frame as shown in FIG. 4 is transmitted and received between base station 100 and mobile stations 200 and 200a. The radio frame includes 10 subframes (subframes # 0 to # 9).

  Radio frame resources are subdivided and managed in the frequency direction and the time direction. In the time direction, a subframe includes two slots. The slot includes 7 (or 6) symbols. The symbol is, for example, an OFDM (Orthogonal Frequency Division Multiple) symbol. An interval signal called CP (Cyclic Prefix) is inserted at the head of each symbol. In the frequency direction, the radio frame includes a plurality of subcarriers. Radio resources on the frequency × time area are allocated to various channels. Radio resource allocation control is performed in units of subframes.

  In the DL subframe, a downlink physical control channel (PDCCH: Physical Downlink Control CHannel) for the base station 100 to transmit an L1 (Layer 1) control signal is transmitted. For the PDCCH, radio resources within a predetermined number of symbols (for example, 3 symbols) from the head of each subframe are used. Also, in the DL subframe, a downlink physical shared channel (PDSCH) for transmitting data signals and L2 / L3 (Layer 2 / Layer 3) control signals is set in the DL subframe. In the UL subframe, an uplink physical shared channel (PUSCH) for transmitting data signals from the mobile stations 200 and 200a is set.

  As a multiple access scheme, for example, OFDMA (Orthogonal Frequency Division Multiple Access) is used for DL radio frames. As the UL radio frame, SC-FDMA (Single-Carrier Frequency Division Multiple Access), NxSC-FDMA (N Times Single-Carrier Frequency Division Multiple Access), or the like is used.

FIG. 5 is a diagram illustrating a transmission example of PDCCH. Here, a case where a control signal addressed to the mobile station 200 is transmitted is considered.
In this example, the mobile station 200 receives data from the base station 100 using CC # 1 and CC2, and transmits data to the base station 100 using CC # 1. That is, PDSCH of mobile station 200 is set to DL CC # 1 and # 2, and PUSCH of mobile station 200 is set to UL CC # 1. Also, the mobile station 200 receives a control signal from the base station 100 at CC # 1. That is, PDCCH of mobile station 200 is set to DL CC # 1. The mobile station 200 detects a control signal to be referred to by the mobile station 200 by monitoring the received signal of CC # 1.

  In this example, a control signal related to PDSCH provided in the same subframe and a control signal related to PDSCH provided in the subframe of CC # 2 at the same timing are transmitted in a subframe having CC # 1. Yes. Furthermore, a control signal related to PUSCH provided in a subframe of CC # 1 after a predetermined time (for example, after 4 subframes) is transmitted. The mobile station 200 detects these three control signals addressed to itself from the subframe of CC # 1, and performs two PDSCH reception processes and one PUSCH transmission process.

  Thus, a control signal related to a physical channel of another CC can be transmitted in a certain CC. That is, in the mobile communication system according to the second embodiment, cross carrier scheduling is possible. Note that PDSCH, PUSCH, and PDCCH can be set for the mobile station 200 a as well as the mobile station 200. In that case, a set (monitoring set) of one or more CCs provided with a PDCCH can be set independently between the mobile station 200 and the mobile station 200a. The PDCCHs of the mobile stations 200 and 200a may be mixed in the same CC.

  FIG. 6 is a diagram illustrating an example of a PDCCH transmission region. A search space (corresponding to the search area described in the first embodiment), which is an area in which the mobile stations 200 and 200a should search for PDCCH, is defined in the radio resource area in which the PDCCH can be set.

  There are two types of search spaces, a common search space and a UE-specific search space. The common search space is used for transmission of a control signal commonly referred to by all mobile stations connected to the base station 100 and a control signal referred to by a plurality of mobile stations. The UE dedicated search space is used for transmission of a control signal referred to by one specific mobile station. The UE individual search space is set for each mobile station. Therefore, the mobile stations 200 and 200a may monitor the radio resource area of the UE-specific search space corresponding to the common search space and the own station.

  The position and size of the common search space are fixed. On the other hand, the position and size of the UE-specific search space are determined by the identifiers given by the mobile stations 200 and 200a from the base station 100, the subframe number to which the search space belongs, and the CCs # 1 to # 5 of the mobile stations 200 and 200a. It changes according to the usage situation. The base station 100 and the mobile stations 200 and 200a calculate the position and size of the UE individual search space of the mobile stations 200 and 200a using a common calculation formula.

  Here, as illustrated in FIG. 6, the common search space and the plurality of UE individual search spaces may be set so as to overlap each other on the radio resource region of frequency × time. This is because not all of the radio resources in the search space are always used, and if the search space is set so as not to overlap, the utilization efficiency of the radio resources is lowered.

  The radio resource of the overlapping part of the common search space and the UE individual search space is preferentially used for the common search space. On the other hand, regarding the radio resources of the overlapping portion between the UE individual search spaces, which UE individual search space has priority is not determined in advance. The base station 100 controls allocation of radio resources for overlapping portions according to the amount of control signals transmitted to the mobile stations 200 and 200a. When the amount of the control signal to be transmitted is large, the base station 100 may pack the control signal in a vacant area of a limited size existing in the search space by increasing the coding rate.

  FIG. 7 is a block diagram showing the structure of the base station. Base station 100 includes carrier aggregation control section 110, PDCCH generation section 120, PDSCH generation section 130, multiplexing section 140, radio transmission section 150, radio reception section 160, and PUSCH processing section 170.

  The carrier aggregation control unit 110 controls carrier aggregation. That is, user data arriving from the upper network is distributed to a plurality of CCs used by the mobile stations 200 and 200a. Then, user data transmitted in each CC is output to PDSCH generation section 130. Further, the carrier aggregation control unit 110 distributes the control signal to one or more CCs included in the monitoring set. Then, the control signal transmitted in each CC is output to PDCCH generating section 120.

  Further, the carrier aggregation control unit 110 determines, for each mobile station, a subframe number, an identifier assigned to the mobile station (sometimes referred to as an RNTI (Radio Network Temporary Identifier)), and the usage status of CCs # 1 to # 5. Determine the location and size of the UE-specific search space. Then, the multiplexing unit 140 is notified of the head position of the UE individual search space, and the size is notified to the PDCCH generation unit 120.

  The PDCCH generation unit 120 encodes and modulates the control signal acquired from the carrier aggregation control unit 110 for each CC, and generates a signal to be transmitted on the PDCCH. As described above, the signal transmitted on the PDCCH includes a signal related to PDSCH and a signal related to PUSCH. Here, PDCCH generation section 120 adjusts the length of the PDCCH signal to be transmitted in the UE dedicated search space according to the size notified from carrier aggregation control section 110. Then, the generated PDCCH signal is output to multiplexing section 140.

  The PDSCH generation unit 130 encodes and modulates user data acquired from the carrier aggregation control unit 110 for each CC, and generates a signal to be transmitted on the PDSCH. Then, the generated PDSCH signal is output to multiplexing section 140.

  The multiplexing unit 140 maps the PDCCH signal acquired from the PDCCH generation unit 120 and the PDSCH signal acquired from the PDSCH generation unit 130 to radio resources in the DL subframe. In particular, multiplexing section 140 maps the PDCCH signal to radio resources in the common search space and the UE dedicated search space. When mapping to the UE individual search space, the head position of each UE individual search space notified from the carrier aggregation control unit 110 is referred to. The multiplexing unit 140 outputs the generated transmission signal to the wireless transmission unit 150.

  The radio transmission unit 150 converts (up-converts) the transmission signal acquired from the multiplexing unit 140 into a radio signal and outputs the radio signal from the antenna. For the conversion to a radio signal, the radio transmission unit 150 includes circuits such as a D / A (Digital to Analog) converter, a frequency converter, and a band pass filter (BPF).

  Radio receiving section 160 converts (down-converts) radio signals received from mobile stations 200 and 200a into baseband signals, and outputs the baseband signals to PUSCH processing section 170. For conversion to a baseband signal, the radio reception unit 160 includes, for example, a circuit such as a low noise amplifier (LNA), a frequency converter, a BPF, and an A / D (Analog to Digital) converter. .

  The PUSCH processing unit 170 demodulates and decodes the baseband signal acquired from the wireless reception unit 160. As a result, user data and higher layer control information transmitted by the mobile stations 200 and 200a on the PUSCH are extracted. The extracted user data is transferred to the upper network. Part of the extracted control information is used for scheduling.

Note that the PDCCH generation unit 120, the PDSCH generation unit 130, and the PUSCH processing unit 170 may be individually provided for each CC in order to perform signal processing for CCs # 1 to # 5.
FIG. 8 is a block diagram showing the structure of the mobile station. The mobile station 200 includes a radio reception unit 210, a separation unit 220, a space calculation unit 230, a PDCCH detection unit 240, a PDCCH processing unit 250, a PDSCH processing unit 260, a PUSCH generation unit 270, and a radio transmission unit 280. The mobile station 200a can also be realized by the same block structure as the mobile station 200.

  Radio receiving section 210 down-converts the radio signal received from base station 100 into a baseband signal and outputs the baseband signal to demultiplexing section 220. For conversion to a baseband signal, the wireless reception unit 210 includes, for example, circuits such as an LNA, a frequency converter, a BPF, and an A / D converter.

  Separating section 220 extracts, for each CC, a signal in a region where PDCCH can be set and a signal in a region where PDSCH can be set from the baseband signal acquired from radio receiving section 210. Then, the extracted PDCCH region signal is output to PDCCH detection unit 240, and the extracted PDSCH region signal is output to PDSCH processing unit 260.

  The space calculation unit 230 calculates the position and size of the UE dedicated search space corresponding to the own station from the subframe number, the identifier assigned to the own station, and the usage status of CC # 1 to # 5. The calculation method corresponds to a method in which the carrier aggregation control unit 110 of the base station 100 determines the position and size. Then, the start position and size of the UE individual search space are notified to the PDCCH detection unit 240.

  The PDCCH detection unit 240 extracts a common search space signal from the signal acquired from the separation unit 220 for each CC included in the monitoring set. Further, from the acquired signal, a signal of an area (UE dedicated search space of the own station) specified by the head position and size notified from the space calculation unit 230 is extracted. Then, the extracted common search space and UE individual search space signals are output to PDCCH processing section 250.

  The PDCCH processing unit 250 searches the signal acquired from the PDCCH detection unit 240 for each CC included in the monitoring set, and extracts a control signal to be referred to by the own station. For example, the PDCCH processing unit 250 performs blind decoding on the acquired signal. Then, the control signal related to PDSCH is output to PDSCH processing section 260, and the control signal related to PUSCH is output to PUSCH generation section 270.

  The PDSCH processing unit 260 acquires a control signal related to PDSCH from the PDCCH processing unit 250. The information indicated by the control signal includes, for example, information on radio resources and data formats for which PDSCH is set. The PDSCH processing unit 260 refers to the control signal and extracts and demodulates and decodes the PDSCH signal from the signal acquired from the demultiplexing unit 220 for each CC used for data communication. Thereby, user data addressed to the own station is acquired.

  The PUSCH generation unit 270 acquires a control signal related to PUSCH from the PDCCH processing unit 250. The information indicated by the control signal includes, for example, information specifying a radio resource in which PUSCH is set and a data format to be used. The PUSCH generation unit 270 refers to the control signal and encodes / modulates user data and higher layer control information transmitted to the base station 100 for each CC used for data communication. Then, the generated transmission signal is output to wireless transmission section 280. Note that the subframe in which PUSCH is set is a predetermined number after the subframe that received the control signal related to PUSCH (for example, after 4 subframes).

  Radio transmission section 280 up-converts the transmission signal acquired from PUSCH generation section 270 into a radio signal and outputs the radio signal from the antenna. For conversion to a radio signal, the radio transmission unit 280 includes circuits such as a D / A converter, a frequency converter, and a BPF, for example.

  Note that the PDCCH detection unit 240, the PDCCH processing unit 250, the PDSCH processing unit 260, and the PUSCH generation unit 270 may be individually provided for each CC in order to perform signal processing for CCs # 1 to # 5.

  FIG. 9 is a flowchart illustrating PDCCH transmission / reception according to the second embodiment. Here, communication between the base station 100 and the mobile station 200 is considered. Communication between the base station 100 and the mobile station 200a can be executed similarly. The process illustrated in FIG. 9 will be described along with step numbers.

  (Step S11) The base station 100 sets a CC (a CC in which PDSCH or PUSCH is set) that the mobile station 200 may use for communication. In each DL subframe, all or a part of the set CCs are used. In addition, the monitoring set of the mobile station 200 is set. Which CC is included in the monitoring set is selected according to the communication data amount and the communication quality of each CC, for example. The base station 100 notifies the mobile station 200 of the CC and monitoring set to be used by PDSCH.

  (Step S12) The base station 100 determines the size of the UE individual search space of the mobile station 200 based on the number of CCs used by the mobile station 200 for communication. The larger the number of CCs used, the larger the UE dedicated search space size. It is conceivable to use the number of CCs in DL as the number of CCs to be used. However, it is also possible to use the number of UL CCs, or the total of the number of DL CCs and the number of UL CCs.

  (Step S13) Similar to the base station 100, the mobile station 200 calculates the size of the UE individual search space of its own station based on the number of CCs to be used. The size calculation formula is set in advance for the base station 100 and the mobile station 200 in advance.

  (Step S14) The base station 100 determines the head position of the UE dedicated search space based on the identifier of the mobile station 200 and the number of the subframe in which the PDCCH signal is transmitted. For example, the calculation is performed by applying a hash function to the identifier and the subframe number.

  (Step S15) For each CC belonging to the monitoring set set in step S11, the base station 100 determines the radio resource area specified by the size determined in step S12 and the head position determined in step S14 as the UE of the mobile station 200. Set to individual search space. The base station 100 maps and transmits the PDCCH signal addressed to the mobile station 200 in the set UE dedicated search space.

  (Step S16) The mobile station 200 calculates the head position of the UE individual search space of the own station based on the identifier of the own station and the number of the currently received subframe. The formula for calculating the head position is set in advance for the base station 100 and the mobile station 200 in advance.

  (Step S17) For each CC belonging to the monitoring set, the mobile station 200 extracts a radio resource area signal specified by the size calculated in step S13 and the head position calculated in step S16. Then, the PDCCH is searched (for example, blind decoding) from the extracted signal of the region, and the control signal addressed to the own station is extracted.

(Step S18) The mobile station 200 performs PDSCH reception processing or PUSCH transmission processing using the control signal extracted in Step S17.
In addition, if said step S11-S13 are performed once, unless CC or monitoring set which the mobile station 200 may use is not changed, it is not necessary to re-execute. However, the number of CCs actually used in each subframe varies up to the value set in step S11. Steps S14 to S18 are repeatedly executed while the base station 100 and the mobile station 200 are communicating.

  FIG. 10 is a diagram illustrating an example of setting a search space according to the second embodiment. In the example in the upper part of FIG. 10, CC # 1 is used for transmission of a control signal addressed to mobile station 200, and CC # 1 and # 2 are used for data transmission addressed to mobile station 200. In this case, the size of the UE individual search space of the mobile station 200 is a size corresponding to “2” which is the number of CCs used.

  On the other hand, in the lower example, the CC used for data transmission addressed to the mobile station 200 is changed to CC # 1 to # 3. In this case, the size of the UE individual search space of the mobile station 200 is a size corresponding to “3” which is the number of CCs used. That is, the size of the UE dedicated search space becomes larger than when the number of CCs used is “2”. As a result, an area that may not overlap with the common search space and other UE individual search spaces increases, and it can be expected that the amount of radio resources that can be used substantially increases.

  According to the mobile communication system of the second embodiment as described above, a UE-specific search space having a size corresponding to the number of CCs used for data communication can be set. That is, when there is a possibility that the amount of control signals to be transmitted in one UE dedicated search space may increase, the UE dedicated search space can be expanded. Therefore, it is possible to balance the increase in the search burden on the mobile stations 200 and 200a by increasing the UE individual search space and the ease of securing radio resources, and to efficiently transmit control signals.

  Note that the method of changing the size of the UE individual search space described above may be applied only to some mobile stations. In this case, the size of the UE individual search space may be fixed for other mobile stations.

[Third Embodiment]
Next, a third embodiment will be described. Differences from the second embodiment will be mainly described, and description of similar matters will be omitted. The mobile communication system according to the third embodiment is different from the second embodiment in the method for determining the size of the UE dedicated search space.

  The mobile communication system of the third embodiment can be realized by the same system configuration as that of the second embodiment shown in FIG. Further, the base station and mobile station of the third embodiment can be realized by the same block structure as that of the second embodiment shown in FIGS. However, the size setting method by the carrier aggregation control unit 110 and the size calculation method by the space calculation unit 230 are different from those of the second embodiment. Hereinafter, the third embodiment will be described using the same reference numerals as those in FIGS.

FIG. 11 is a flowchart illustrating PDCCH transmission / reception according to the third embodiment. The processing illustrated in FIG. 11 will be described along with step numbers.
(Step S21) The base station 100 sets CCs that the mobile station 200 may use for communication. In addition, the monitoring set of the mobile station 200 is set. The base station 100 notifies the mobile station 200 of the CC and monitoring set to be used by PDSCH.

  (Step S22) The base station 100 determines the size of the UE-specific search space of the mobile station 200 based on the difference between the number of CCs used by the mobile station 200 for communication and the number of CCs included in the monitoring set of the mobile station 200. decide. The larger the difference is, the larger the UE dedicated search space size is.

  (Step S23) Similar to the base station 100, the mobile station 200 calculates the size of the UE individual search space of its own station based on the difference between the number of CCs to be used and the number of CCs included in the monitoring set.

(Step S24) The base station 100 determines the head position of the UE dedicated search space based on the identifier of the mobile station 200 and the number of the subframe in which the PDCCH signal is transmitted.
(Step S25) The base station 100 determines, for each CC belonging to the monitoring set set in step S21, the radio resource area specified by the size determined in step S22 and the head position determined in step S24, as the UE of the mobile station 200. Set to individual search space. The base station 100 maps and transmits the PDCCH signal addressed to the mobile station 200 in the set UE dedicated search space.

(Step S26) The mobile station 200 calculates the head position of the UE individual search space of the own station based on the identifier of the own station and the number of the currently received subframe.
(Step S27) For each CC belonging to the monitoring set, the mobile station 200 extracts a radio resource area signal specified by the size calculated in step S23 and the head position calculated in step S26. Then, the PDCCH is searched from the extracted signal of the area, and the control signal addressed to the own station is extracted.

(Step S28) The mobile station 200 performs PDSCH reception processing or PUSCH transmission processing using the control signal extracted in step S27.
FIG. 12 is a diagram illustrating an example of setting a search space according to the third embodiment. In the upper example of FIG. 12, CC # 1 and # 2 are used for transmission of control signals addressed to mobile station 200, and CC # 1 to # 3 are used for data transmission addressed to mobile station 200. In this case, the size of the UE individual search space of the mobile station 200 is a size corresponding to “1” which is the difference between the number of CCs used and the number of CCs included in the monitoring set.

  On the other hand, in the lower example, the CC used for transmission of the control signal addressed to the mobile station 200 is changed to CC # 1. In this case, the size of the UE individual search space of the mobile station 200 is a size corresponding to “2” that is the difference between the number of CCs used and the number of CCs included in the monitoring set. That is, the size of the UE individual search space is larger than when the difference is “1”. As a result, an area that may not overlap with the common search space and other UE individual search spaces increases, and it can be expected that the amount of radio resources that can be used substantially increases.

  According to the mobile communication system of the third embodiment as described above, a UE-specific search space having a size corresponding to the difference between the number of CCs used for data communication and the number of CCs used for transmission of control signals can be set. That is, even if the monitoring set is variable, the UE dedicated search space can be expanded when the amount of control signals transmitted in the UE dedicated search space per CC may increase. Therefore, it is possible to balance the increase in the search burden on the mobile stations 200 and 200a by increasing the UE individual search space and the ease of securing radio resources, and to efficiently transmit control signals.

  Note that the above-described method for changing the size of the UE individual search space may be applied only to some mobile stations, and the size may be fixed for other mobile stations. Further, the method of the second embodiment and the method of the third embodiment may be used in combination. For example, the method of the third embodiment can be applied only to some CCs or some mobile stations, and the method of the second embodiment can be applied to other CCs or mobile stations. .

[Fourth Embodiment]
Next, a fourth embodiment will be described. Differences from the second and third embodiments will be mainly described, and description of similar matters will be omitted. The mobile communication system according to the fourth embodiment makes the head position of the UE dedicated search space variable according to the usage status of CCs # 1 to # 5.

  The mobile communication system of the fourth embodiment can be realized by the same system configuration as that of the second embodiment shown in FIG. The base station and mobile station of the fourth embodiment can be realized by the same block structure as that of the second embodiment shown in FIGS. However, the start position setting method by the carrier aggregation control unit 110 and the start position calculation method by the space calculation unit 230 are different from those of the second embodiment. Hereinafter, the fourth embodiment will be described using the same reference numerals as those in FIGS.

FIG. 13 is a flowchart illustrating PDCCH transmission / reception according to the fourth embodiment. The process illustrated in FIG. 13 will be described along with step numbers.
(Step S31) The base station 100 sets a CC that the mobile station 200 may use for communication. In each DL subframe, all or a part of the set CCs are used. In addition, the monitoring set of the mobile station 200 is set. The base station 100 notifies the mobile station 200 of the CC and monitoring set to be used by PDSCH.

  (Step S32) For each CC belonging to the monitoring set set in step S31, the base station 100 identifies the identifier of the mobile station 200, the number of the subframe that transmits the PDCCH signal, and the carrier indicator (CI) that is the identifier of the CC. ) To determine the start position of the UE-specific search space of the mobile station 200.

  That is, even if it is UE separate search space of the same timing and the same mobile station, a position is made to differ with CC. For example, a method of determining the head position by setting an offset according to the CI for the position calculated based on the identifier of the mobile station 200 and the subframe number is conceivable. Note that the size of the UE individual search space is fixed.

  (Step S33) The base station 100 determines, for each CC belonging to the monitoring set set in step S31, a radio resource area specified by a predetermined size and the head position determined in step S32, as a UE-specific search space for the mobile station 200. Set to. The base station 100 maps and transmits the PDCCH signal addressed to the mobile station 200 in the set UE dedicated search space.

  (Step S34) The mobile station 200, for each CC belonging to the monitoring set, based on its own identifier, the number of the currently received subframe, and the CI of that CC, the head position of its own UE individual search space Is calculated. The formula for calculating the head position is set in advance for the base station 100 and the mobile station 200 in advance.

  (Step S35) For each CC belonging to the monitoring set, the mobile station 200 extracts a radio resource region signal specified by a predetermined size and the head position calculated in step S34. Then, the PDCCH is searched from the extracted signal of the area, and the control signal addressed to the own station is extracted.

(Step S36) The mobile station 200 performs PDSCH reception processing or PUSCH transmission processing using the control signal extracted in step S35.
In addition, if said step S31 is performed once, it does not need to be re-executed unless CC and the monitoring set which the mobile station 200 may use change. However, the number of CCs actually used in each subframe varies up to the value set in step S31. Steps S32 to S36 are repeatedly executed while the base station 100 and the mobile station 200 are communicating.

  FIG. 14 is a diagram illustrating an example of setting a search space according to the fourth embodiment. In this example, CC # 1 and # 2 are used for transmission of a control signal addressed to the mobile station 200. The head position of each UE dedicated search space for CC # 1 and CC # 2 is a position corresponding to the combination of the identifier of mobile station 200, the subframe number, and the CI for CC # 1 and CC # 2.

  That is, the head position of the UE dedicated search space differs between CC # 1 and CC # 2. For example, the head position in CC # 2 is shifted to the rear side of the head position in CC # 1. As a result, even if one CC has a large area overlapping with the common search space or another UE-specific search space, it can be expected that the area that may overlap with the other CC is reduced. Therefore, an area that may not overlap with the common search space and other UE individual search spaces increases, and it can be expected that the amount of radio resources that can be used substantially increases.

  According to such a mobile communication system of the fourth embodiment, the position of the UE dedicated search space can be changed according to the CC used for transmission of the control signal. That is, there is a high possibility that at least one CC can secure sufficient radio resources used for transmission of the control signal. Therefore, the control signal can be transmitted efficiently.

  In the fourth embodiment, the head position of the UE individual search space is changed by the CC, but the size may be changed by the CC instead of the head position. Moreover, you may change both a head position and size by CC. Further, the above-described method for changing the head position may be applied only to some mobile stations. Further, the methods of the second and third embodiments and the method of the fourth embodiment may be used in combination.

[Fifth Embodiment]
Next, a fifth embodiment will be described. Differences from the second to fourth embodiments will be mainly described, and description of similar matters will be omitted. The mobile communication system according to the fifth embodiment is different from the fourth embodiment in the method for determining the head position of the UE dedicated search space.

  The mobile communication system of the fifth embodiment can be realized by the same system configuration as that of the second embodiment shown in FIG. Further, the base station and mobile station of the fifth embodiment can be realized by the same block structure as that of the second embodiment shown in FIGS. However, the start position setting method by the carrier aggregation control unit 110 and the start position calculation method by the space calculation unit 230 are different from those of the second embodiment. Hereinafter, the fifth embodiment will be described using the same reference numerals as those in FIGS.

FIG. 15 is a flowchart illustrating PDCCH transmission / reception according to the fifth embodiment. The process illustrated in FIG. 15 will be described in order of step number.
(Step S41) The base station 100 sets a CC that the mobile station 200 may use for communication. In each DL subframe, all or a part of the set CCs are used. In addition, the monitoring set of the mobile station 200 is set. The base station 100 notifies the mobile station 200 of the CC and monitoring set to be used by PDSCH.

  (Step S42) Based on the identifier of the mobile station 200 and the number of the subframe in which the PDCCH signal is transmitted, the base station 100 calculates the head position of the UE dedicated search space of the mobile station 200. Note that the size of the UE individual search space is fixed.

  (Step S43) The base station 100 determines whether there is a large overlap between the UE individual search space and the common search space when the number of CCs to be used is large and the head position calculated in Step S42 is adopted. If this condition is satisfied, the process proceeds to step S44. If the condition is not satisfied, the process proceeds to step S45.

  As a method for determining whether or not the number of CCs to be used is large, it is conceivable to determine whether or not the number of CCs to be used is equal to or greater than a predetermined threshold (for example, “3”). Further, it is conceivable to determine whether the difference between the number of CCs to be used and the number of CCs included in the monitoring set is equal to or greater than a predetermined threshold (for example, “2”). In addition, as a method of determining whether or not there is a large overlap between the UE individual search space and the common search space, is the distance between the head position of the UE individual search space and the head position of the common search space equal to or greater than a predetermined threshold value? It is possible to judge.

  (Step S44) The base station 100 corrects the head position by setting an offset to the head position calculated in Step S42. For example, the offset amount may be a fixed amount such as the length of the common search space. It is also conceivable that the offset amount is a variable amount according to the number of CCs used by the mobile station 200 or the difference between the number of CCs used and the number of CCs included in the monitoring set.

  (Step S45) The base station 100 sets, for each CC belonging to the monitoring set, a radio resource area specified by a predetermined size and the determined head position in the UE individual search space of the mobile station 200. The base station 100 maps and transmits the PDCCH signal addressed to the mobile station 200 in the set UE dedicated search space.

(Step S46) The mobile station 200 calculates the head position of the UE individual search space of the own station based on the identifier of the own station and the number of the currently received subframe.
(Step S47) The mobile station 200 determines whether or not the same conditions as those in step S43 are satisfied based on the number of CCs to be used and the head position calculated in step S46. If the condition is satisfied, an offset is set at the calculated head position to correct the head position.

  (Step S48) For each CC belonging to the monitoring set, the mobile station 200 extracts a radio resource area signal specified by a predetermined size and the head position calculated in step S47. Then, the PDCCH is searched from the extracted signal of the area, and the control signal addressed to the own station is extracted.

(Step S49) The mobile station 200 performs PDSCH reception processing or PUSCH transmission processing using the control signal extracted in step S48.
FIG. 16 is a diagram illustrating a setting example of a search space according to the fifth embodiment. In the upper example of FIG. 16, CC # 1 is used for transmission of a control signal addressed to mobile station 200, and CC # 1 and # 2 are used for data transmission addressed to mobile station 200. In this case, even if the UE individual search space determined from the identifier of the mobile station 200 and the subframe number overlaps with the common search space, no offset is set.

  On the other hand, in the lower example, CCs used for data transmission addressed to the mobile station 200 are expanded to CC # 1 to # 3. In this case, if the UE individual search space determined from the identifier of the mobile station 200 and the subframe number overlaps with the common search space, the position of the UE individual search space is shifted in a direction away from the common search space. That is, it can be expected that the overlapping area between the common search space and the UE-specific search space of the mobile station 200 decreases, and the amount of radio resources that can be used substantially increases.

  According to the mobile communication system of the fifth embodiment as described above, the position of the UE individual search space can be corrected according to the number of CCs used for data communication and the degree of overlap with the common search space. That is, if the amount of control signals transmitted in the UE dedicated search space may increase and the amount of radio resources that can be used substantially decreases due to overlap with the common search space, it is common. The amount of overlap with the search space can be reduced. Therefore, it becomes easy to secure radio resources used for transmitting the control signal, and the control signal can be efficiently transmitted.

  In addition to the method of the fifth embodiment, the size of the UE individual search space may be further changed according to the usage status of CCs # 1 to # 5. Further, the above-described method for changing the head position may be applied only to some mobile stations. Moreover, you may use combining the method of 2nd-4th embodiment, and the method of 5th Embodiment.

  The above merely illustrates the principle of the present invention. In addition, many modifications and variations will be apparent to practitioners skilled in this art and the present invention is not limited to the precise configuration and application shown and described above, and all corresponding modifications and equivalents may be And the equivalents thereof are considered to be within the scope of the invention.

DESCRIPTION OF SYMBOLS 10,20 Wireless communication apparatus 11 Control part 12 Transmission part 21 Calculation part 22 Detection part

Claims (2)

A wireless communication method in a wireless communication device that communicates with another wireless communication device using a plurality of component carriers,
Based on the information on the use of the plurality of component carriers, a region of a predetermined size of radio resources in which the other radio communication device searches for a control signal is set,
Transmitting a control signal addressed to the other radio communication device within the set radio resource area ;
The information on the use of the plurality of component carriers includes information on the component carrier that sets an area of the radio resource,
According to a subframe number for transmitting a control signal addressed to the other radio communication device and an identifier of a component carrier that sets the radio resource area, the position of the radio resource area is changed , Wireless communication method. A wireless communication device that communicates with other wireless communication devices using a plurality of component carriers,
Based on the information on the use of the plurality of component carriers, an area of a radio resource of a predetermined size in which the other radio communication device searches for a control signal is set, and within the set radio resource area, A control unit that transmits a control signal addressed to the wireless communication device;
The information on the use of the plurality of component carriers includes information on the component carrier that sets an area of the radio resource,
The position of the radio resource area is changed according to a subframe number for transmitting a control signal addressed to the other radio communication apparatus and an identifier of a component carrier that sets the radio resource area.
A wireless communication device.

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