JP2017085416A - Base station device, terminal device, communication method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid conflict of resources used by a plurality of communication devices.SOLUTION: A base station device can transmit a signal to a terminal device and receive an acknowledgment from the terminal device. The base station device sets resources for the terminal device to use to transmit an acknowledgment on the basis of length of a period from reception of the signal by the terminal device to transmission of the acknowledgment, transmits information to specify the set resources to the terminal device, and receives the acknowledgment transmitted by the terminal device by using the set resources. Here, a plurality of resources which can be used for transmission of an acknowledgment are associated with different respective indexes, and information specifying a resource is information on a value of difference between the value of an index of a set resource and the value of an index of a resource used when the length of the period is prescribed length.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a technique for designating resources to be used in a wireless communication system.

  In recent years, many wireless communication apparatuses have used a complex automatic repeat request (HARQ). In HARQ, with respect to a signal transmitted by a transmission-side device, the reception-side device transmits an acknowledgment (ACK / NACK) indicating whether or not the signal has been successfully received to the transmission-side device. In response to the confirmation response, the transmitting device retransmits the signal. Here, the signal at the time of retransmission may be the same signal as the signal transmitted before retransmission, or may be a different signal. For example, a signal including a redundant component different from that at the first transmission can be transmitted at the second and subsequent retransmissions.

  Here, when the confirmation response is transmitted, a communication resource for transmitting the confirmation response is required. For example, in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), a terminal device determines a resource for transmitting an acknowledgment (HARQ-ACK) according to a signal transmitted on a downlink by a base station device. (Refer nonpatent literature 1). Here, the resource can include, for example, at least one of a frequency band (frequency channel), time (time slot), and code (symbol).

  In LTE, a base station apparatus controls transmission in a physical downlink shared channel (PDSCH) using a physical downlink control channel (PDCCH). On the frequency axis used for the transmission of HARQ-ACK, the terminal apparatus confirms the acknowledgment related to the signal transmitted on the PDSCH based on the head index of the CCE for itself among the CCEs (control channel elements) included in the PDCCH. Determine the location and code. Here, in the current LTE standard, HARQ-ACK is transmitted 4 subframes (4 milliseconds later) from the subframe in which a signal is transmitted and received. Here, the length of a period from when a signal is transmitted / received to when HARQ-ACK is transmitted is referred to as HARQ round trip time (RTT). The terminal apparatus determines the position and code of the resource block in the frequency direction to transmit HARQ-ACK according to the index of the CCE addressed to itself, and after 4 subframes, determines the resource block and code of the determined position. To transmit HARQ-ACK. As described above, in the LTE standard, the HARQ RTT is determined to be a time corresponding to four subframes, and the frequency and code are determined by the CCE addressed to each terminal device. Therefore, HARQ transmitted by a plurality of terminal devices respectively. -ACKs do not collide with each other. Note that HARQ-ACK transmitted in response to the base station apparatus receiving a signal from the terminal apparatus is also transmitted to the plurality of terminal apparatuses using different resources.

3GPP TS 36.213

  As an extension of LTE-Advanced, it has been studied that the HARQ RTT is shortened. In this case, since the length of the RTT may be different for each terminal device, there may occur a case where HARQ-ACK transmitted to the PDSCH transmitted at different timings is transmitted at the same timing. In this case, since the PDSCH and the corresponding PDCCH are transmitted at different timings, there is a possibility that the leading indexes of CCEs for different terminal apparatuses included in these PDCCHs match. That is, the conventional technique has a problem that resource contention may occur even when resources for HARQ-ACK transmission do not compete.

  The present invention has been made in view of the above problems, and an object thereof is to provide a technique for avoiding contention for resources used by a plurality of communication apparatuses.

  To achieve the above object, a base station apparatus according to the present invention is a base station apparatus capable of transmitting a signal to a terminal apparatus and receiving an acknowledgment from the terminal apparatus, wherein the terminal apparatus receives the signal. And setting means for setting a resource that the terminal device should use for transmitting the confirmation response based on a length of a period from when the confirmation response is transmitted to the terminal, and information for specifying the set resource A plurality of resources that can be used for transmitting the confirmation response, each having a transmission unit that transmits to the device and a reception unit that receives the confirmation response transmitted using the resource set by the terminal device. When the transmission unit is associated with a different index, and the transmission unit sets the value of the resource index set by the setting unit and the length of the period is a predetermined length Transmitting a value for the difference value between the value of the index of a resource to be used as the information, characterized in that.

  In order to achieve the above object, a terminal apparatus according to the present invention is a terminal apparatus capable of receiving a signal from a base station apparatus and transmitting an acknowledgment to the base station apparatus after a predetermined period, Receiving means for receiving information specifying a resource to be used for transmission of the confirmation response from the base station apparatus; and specifying means for specifying a resource for transmitting the confirmation response based on the information; Transmission means for transmitting the confirmation response using the identified resource, and a plurality of resources that can be used for transmission of the confirmation response are respectively associated with different indexes, and the information includes the information A value of an index of a resource to be used when the terminal apparatus transmits the confirmation response to the base station apparatus after the predetermined period after receiving the signal; Including a value related to a difference value from a value of a resource index used when a length of a period from reception of the signal from the ground station device to transmission of the confirmation response is a predetermined length, and the specifying unit includes: From the difference value and the value of the index of the resource used when the length of the period from reception of the signal from the base station apparatus to transmission of the confirmation response is a predetermined length, the base station apparatus A resource for transmitting the confirmation response after the predetermined period after receiving the signal from is identified.

  According to the present invention, contention for resources used by a plurality of communication devices can be avoided.

The figure which shows the structural example of a radio | wireless communications system. The figure which shows the hardware structural example of a base station apparatus and a terminal device. The block diagram which shows the function structural example of a base station apparatus. The block diagram which shows the function structural example of a terminal device. The figure which shows the flow of the process performed in a radio | wireless communications system. The conceptual diagram which shows the 1st example of the resource designation | designated method notified. The conceptual diagram which shows the 2nd example of the resource designation | designated method notified. The conceptual diagram which shows the 3rd example of the resource designation | designated method notified. The conceptual diagram which shows the 4th example of the resource designation | designated method notified.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Wireless communication system)
FIG. 1 shows a configuration example of a wireless communication system according to this embodiment. The wireless communication system includes, for example, a long term evolution (LTE) base station apparatus and a plurality of terminal apparatuses. Note that the configuration and procedure described below are particularly effective when there are a plurality of terminal devices, but are not of a nature that cannot be applied when there is only one terminal device. That is, the following discussion can be applied even when only one terminal device exists under the control of the base station device (the base station device is connected as a serving base station). Similarly, a plurality of base station apparatuses may exist as in a normal cellular communication system.

  In the following description, it is assumed that a data signal is transmitted from the base station apparatus to the terminal apparatus mainly in the downlink, and the terminal apparatus transmits an acknowledgment (HARQ-ACK) in response to receiving the data signal. However, the technology according to the present embodiment can be used in any wireless communication system in which an acknowledgment is transmitted. For example, when a data signal is transmitted in the uplink and an acknowledgment is transmitted in the downlink, The following discussion can also be applied to intercommunication. Here, the confirmation response can be configured by at least one of an affirmative response and a negative response. That is, only one of a positive response or a negative response may be used, or both may be used.

  Here, as described above, from the transmission of the data signal from the device on the data transmission side (base station device) to the device on the reception side (terminal device), the device on the reception side for the data signal to the device on the transmission side. The length of the period until the confirmation response is transmitted is called a round trip time (RTT). In the present embodiment, a different RTT may be used for each terminal device. In other words, the first terminal device can use the first RTT, and the second terminal device can use a second RTT different from the first RTT. Also, in one terminal device, different RTTs can be used depending on the situation, for example, depending on the communication mode required by the application in use and the state of the terminal device. That is, a certain terminal device can use the first RTT at the first time and use the second RTT at the second time. It is assumed that some terminal devices do not support the reduction of RTT, and the RTT in such a terminal device can be 4 milliseconds (4 subframes). Note that although the RTT is mainly shortened here, there may be a terminal device that sets the RTT to a time longer than 4 milliseconds.

  Conventionally, RTT is fixed at 4 milliseconds. For this reason, each terminal apparatus determines resources according to the head index of the control channel element (CCE) in the PDCCH (physical downlink control channel), which is control information included in the signal transmitted by the base station apparatus. I was able to prevent that conflict. However, if some terminal devices use RTT shorter or longer than 4 milliseconds, resource contention may occur even if each terminal device determines resources by CCE addressed to itself included in the PDCCH. For example, a relationship between a conventional terminal device that receives a signal in the j-th subframe (that is, an RTT of 4 milliseconds) and a terminal device that receives a signal in the j + 1-th subframe of 3 milliseconds. consider. Since the CCEs addressed to these terminal devices have different subframe numbers, they may have the same head index. For this reason, as a result, the position on the frequency axis of the resource block used by the terminal device for HARQ-ACK overlaps with the code, and the time also overlaps due to the difference in RTT. As a result, two HARQ-ACKs collide, and the base station apparatus may not be able to receive the confirmation response accurately.

  In the present embodiment, in order to prevent such resource contention from occurring, the position of the resource used in HARQ-ACK is shifted according to the value of RTT used by the terminal apparatus. Here, it is assumed that resources that can be used for transmission of HARQ-ACK are associated with separate indexes. The resource here includes at least one of a frequency position of a physical uplink control channel (PUCCH) and a code (symbol). The code here is a code for code multiplexing. Thus, multiple indexes may be associated with the same frequency location, and multiple indexes may be associated with the same code. However, different indexes are associated with different combinations of frequency positions and codes.

  And the base station apparatus which concerns on this embodiment sets the index of the resource (frequency position and code) which should be used with respect to the terminal device whose RTT length is not predetermined length (for example, 4 milliseconds), for example , Information related thereto is transmitted to the terminal device. This information may be, for example, a difference value between the index value of the resource to be used when the RTT length is a predetermined length and the index value of the resource to be actually used by the terminal device. Here, since the base station apparatus knows the value of RTT used by each of the connected terminal apparatuses and has determined the signal transmission schedule in the downlink, it can determine which terminal for each subframe. It is possible to know whether the device transmits HARQ-ACK. Therefore, the base station apparatus can set the index of the resource used by each terminal apparatus so that the resources used for HARQ-ACK transmission do not compete in the same subframe. Note that the base station apparatus does not need to set the index of the resource to be used again for the terminal apparatus having a predetermined value such as 4 milliseconds for the RTT to be used. While the terminal device using the conventional RTT value (4 milliseconds) can determine the resource only by the head index of the conventional CCE, even if the base station device transmits information about the index, the information It is because there is a case where it does not understand. As described above, the base station apparatus according to the present embodiment, based on the length of the period (RTT) from when the terminal apparatus receives the downlink signal until it transmits the confirmation response, the terminal apparatus A resource to be used for transmission can be set, and information related to the resource can be notified to the terminal device.

  For example, the terminal device specifies an index of a resource to be used for HARQ-ACK when the RTT is 4 milliseconds from the head index of the CCE addressed to the terminal device. Then, the terminal apparatus shifts the index of the identified resource by the amount of the difference value included in the received resource information, and uses the resource corresponding to the shifted index for actual HARQ-ACK transmission. Identify as a resource. As described above, the difference value included in the information on the resource is used as the shift amount of the resource index in the terminal device. Accordingly, the terminal device can prevent the HARQ-ACK from being transmitted using the same resource at the same timing as other terminal devices under the control of the base station device. In addition, when the difference value is unified as either positive or negative by sending the difference value information as information about the resource, compared to directly specifying the index to be used, The amount of information related to the designation can be reduced. Further, even if the difference value can be both positive and negative, the amount of information related to the resource designation can be reduced by restricting the range. In this way, when the RTT is 4 milliseconds, the signaling overhead is reduced by using the difference value between the index of the resource to be used for HARQ-ACK transmission and the index of the resource to be actually used for notification. can do.

  The difference value information may be separately notified to each of one or more terminal devices. For example, information for each RTT value is broadcast to some or all terminals. May be notified. That is, when the first terminal device and the second terminal device use the same RTT, information of one difference value may be notified to these terminal devices, or two different difference values are respectively provided. May be notified. Further, when the difference value information is individually notified to each terminal device, a field addressed to each terminal device in the PDCCH (physical downlink control channel) may be used for notification of the information, Another channel may be used. Note that, when the difference value information is notified to one or more terminal devices, the information may be broadcast using SIB (System Information Block) or the like. Note that for a predetermined value such as RTT of 4 milliseconds, the difference value of the index of the resource does not have to be set again as described above. Similarly, the difference of the index corresponding to the RTT of 4 milliseconds is used. The value information may not be notified to the terminal device. That is, for example, when information is individually notified to each terminal device, difference value information does not need to be notified to a terminal device with an RTT of 4 milliseconds, and when broadcast notification is made. Alternatively, the information on the difference value regarding the RTT of 4 milliseconds may be excluded.

  In a certain aspect, the base station apparatus actually operates within the range of the conventional PUCCH (physical uplink control channel) resource, that is, within the range of the resource index that can be taken when the RTT is 4 milliseconds, for example. The resource to be used can be specified. This is useful when the number of terminal apparatuses that are targets of data transmission by PDSCH is not large compared to the actual PUCCH resource amount.

  In another aspect, the base station apparatus identifies a resource to be actually used outside the range of the conventional PUCCH resource, that is, outside the range of the resource index that can be taken when, for example, the RTT is 4 milliseconds. can do. According to this, it becomes possible to prevent a HARQ-ACK transmitted by a terminal apparatus using an RTT other than 4 milliseconds from colliding with an HARQ-ACK transmitted by a terminal apparatus using an RTT of 4 milliseconds. .

The difference value information may be notified by the number of CCE indexes included in the PDCCH or the number of OFDM symbols used for PDCCH transmission. Here, the number of target CCE indexes and the number of OFDM symbols are values related to a terminal apparatus that transmits HARQ-ACK at the same timing. That is, for example, the following terminals may transmit HARQ-ACK simultaneously with a terminal apparatus that transmits an acknowledgment response after one subframe (j + 4th subframe) after receiving a signal in the j + 3th subframe: It becomes a device.
(1) A terminal device that receives a signal in the j + 2nd subframe and transmits HARQ-ACK after two subframes.
(2) A terminal device that receives a signal in the (j + 1) th subframe and transmits HARQ-ACK after three subframes.
(3) A terminal device that receives a signal in the j-th subframe and transmits HARQ-ACK after 4 subframes.

  In this case, the total number of PDCCH CCE indexes used for signal transmission from the base station apparatus in each of (1) to (3) is the number of terminal apparatuses that can simultaneously transmit HARQ-ACK in the j + 4th subframe. It corresponds to. For this reason, for example, a terminal apparatus that transmits an acknowledgment after one subframe after receiving a signal in the j + 3rd subframe shifts the resource index by the shift amount corresponding to the total number of (1) to (3) described above. The resource to be used can be specified. For example, when the total amount of the above (1) to (3) is 100, the terminal device can shift the resource index by 100. According to this, HARQ-ACK transmitted by the terminal devices of (1) to (3) and HARQ-ACK transmitted by the terminal device that transmits an acknowledgment after one subframe after receiving the signal in the j + 3rd subframe. Does not use the same resource. Similarly, for example, a terminal device that transmits an acknowledgment after two subframes receiving a signal in the j + 2nd subframe can shift the resource index by an amount corresponding to the total number of (2) and (3) described above. . Also, for example, a terminal apparatus that transmits an acknowledgment after 3 subframes receiving a signal in the (j + 1) th subframe can shift the resource index by an amount corresponding to the number of (3) above. In the above description, the total number of CCE indexes for the terminal devices corresponding to the above-described (1) to (3) is notified. However, depending on whether or not it corresponds to (1) to (3). Alternatively, the total number of CCEs set in the jth to j + 2nd subframes may be notified.

  In addition, the above-mentioned total may be notified by the number of OFDM symbols used for transmission of PDCCH. That is, as for PDCCH, 1 to 3 OFDM symbols are used for each subframe, but the terminal apparatus may specify the above-mentioned total number according to the number. In this case, when the number of OFDM symbols is 1, 2, and 3, it can be handled that the number of CCE indexes described above is 8, 25, and 41, respectively. At this time, the terminal apparatus that transmits an acknowledgment response after one subframe of receiving the signal in the j + 3rd subframe observes the PCFICH (physical control format indicator channel) of the jth to j + 2th subframe and obtains this information. You may get it. In this case, the terminal device can specify the shift amount of the resource to be used by the conventional PCFICH. For example, the base station apparatus transmits, for example, an OFDM symbol of the PDCCH used in the jth to j + 2 subframes to a terminal apparatus that transmits an acknowledgment after one subframe after receiving a signal in the j + 3th subframe. The total number of numbers may be notified. In this case, for example, the terminal device may specify the maximum number of CCEs that can be considered to be set from the obtained information on the total number of OFDM symbols, and specify the shift amount of the resource index according to the result. . Here, the case has been described where the RTT is set in units of 1 millisecond from 1 millisecond to 4 milliseconds, but is not limited thereto. That is, information on the number of CCEs or the number of OFDM symbols of PDCCH is reported from the base station apparatus to the terminal apparatus over a predetermined period of a length corresponding to the difference between the RTT of the predetermined length and the actually used RTT. As such, it can be generalized.

  As described above, the terminal apparatus transmits HARQ-ACK using a resource different from the case where the RTT is 4 milliseconds according to the RTT used by the terminal apparatus. As a result, it becomes possible for a plurality of terminal devices having the same timing to transmit HARQ-ACK to distribute resources used for HARQ-ACK transmission, and it is difficult for resource contention to occur.

  Below, the structure of the base station apparatus and terminal device which perform such a process, and the flow of the process which they perform are demonstrated in detail.

(Hardware configuration of base station device and terminal device)
FIG. 2 shows a hardware configuration example of the base station device and the terminal device. For example, the base station apparatus and the terminal apparatus have a hardware configuration as shown in FIG. 2, and include, for example, a CPU 201, a ROM 202, a RAM 203, an external storage device 204, and a communication device 205. In the base station device and the terminal device, for example, the CPU 201 executes a program that realizes each function of the base station device and the terminal device as described above, which is recorded in any of the ROM 202, the RAM 203, and the external storage device 204.

  And a base station apparatus and a terminal device control the communication apparatus 205 by CPU201, for example, and perform communication between a base station apparatus and a terminal device. In addition, in FIG. 2, although the base station apparatus and the terminal device have shown the schematic diagram which has the one communication apparatus 205, it is not restricted to this. For example, the base station device may include a communication device for communication between base station devices and a communication device between terminal devices. Furthermore, the terminal device can include, for example, a communication device for communication with the base station device and a communication device for communication between terminals.

  Note that the base station device and the terminal device may be provided with dedicated hardware for executing each function, or a part of the base station device and the terminal device may be executed by the hardware, and the other part may be executed by a computer that operates the program. . All functions may be executed by a computer and a program.

(Functional configuration of base station equipment)
FIG. 3 shows a functional configuration example of the base station apparatus. As described above, the base station apparatus has a function of notifying information on resources for the terminal apparatus to transmit HARQ-ACK. The base station apparatus includes, for example, a wireless communication unit 301, a resource setting unit 302, a resource designation information notification unit 303, and a retransmission control unit 304 as functional configurations. In addition, in this example, although only the functional block regarding the notification control of the designation | designated information of the resource relevant to HARQ-ACK as mentioned above is shown, a base station apparatus is a base station apparatus for normal cellular communication. Of course it has the function of.

  The wireless communication unit 301 transmits a wireless signal to the terminal device and receives a wireless signal from the terminal device. Here, the radio signal transmitted from the base station apparatus to the terminal apparatus includes, for example, a data signal addressed to the terminal apparatus and a control signal for transmitting the data signal. Here, the control signal includes, for example, a physical downlink control channel (PDCCH), and the PDCCH uses a control channel element (CCE) as control information addressed to each of a plurality of terminal devices that are counterpart devices that transmit data signals. Including. Moreover, the radio signal transmitted from the terminal device to the base station device includes an acknowledgment (HARQ-ACK) signal for the data signal transmitted by the base station device.

  Note that the wireless communication unit 301 can also receive a data signal and a control signal from the terminal device and transmit HARQ-ACK to the data signal. The wireless communication unit 301 can also transmit and receive various other signals.

  As described above, the resource setting unit 302 sets an index value of a resource to be actually used for HARQ-ACK transmission for each terminal apparatus.

  The resource designation information notifying unit 303 specifies a difference value between the index value set by the resource setting unit 302 and the resource index value when the HARQ RTT is 4 milliseconds. Then, the resource designation information notification unit 303 notifies the specified information to each terminal device via the wireless communication unit 301. Here, the same information may be notified to each of the one or more terminal devices, or different information may be notified for each terminal device. The information to be notified is information on a difference value for enabling the terminal device to specify a resource actually used for HARQ-ACK transmission from the information and a resource index used when the RTT is 4 milliseconds. It is. Further, the resource here includes a frequency position and a code as described above. The time is specified by the RTT used by each terminal device.

  Note that the resource setting unit 302 may set the index of the resource that should actually be used for each terminal device, or may set the difference value of the resource index that should be used for each RTT. Note that the resource designation information notification unit 303 can notify different information for each terminal device in the former case, and can simultaneously notify the same difference value to terminal devices using the same RTT in the latter case. Note that the resource designation information notification unit 303 may notify a plurality of difference values respectively corresponding to a plurality of RTTs to a part or all of the terminal devices existing around the base station device. In this case, an information field corresponding to each of a plurality of RTTs is prepared in the notification message, and the notification of the RTT value can be omitted by storing the difference value information in the field. . This is because when the terminal device acquires the difference value information, the terminal device can know the corresponding RTT value depending on which field the difference value information is stored in.

  The retransmission control unit 304 executes processing related to composite automatic retransmission control by HARQ. For example, the retransmission control unit 304 extracts the HARQ-ACK component from the uplink signal including the HARQ-ACK received via the wireless communication unit 301, and transmits the data signal via the wireless communication unit 301 as necessary. Perform resend. Note that the retransmission control unit 304 knows that the resource set by the resource setting unit 302 is used for each terminal device to transmit HARQ-ACK. Therefore, retransmission control section 304 can reliably receive HARQ-ACK transmitted from each terminal device.

(Configuration of terminal device)
FIG. 4 shows a functional configuration example of the terminal device. The terminal device includes, for example, a wireless communication unit 401, a resource specifying unit 402, and a retransmission control unit 403 as its functional configuration. Note that, in this example, only functional blocks related to retransmission control, in particular, a resource identification method at the time of HARQ-ACK transmission, are shown, but the terminal device naturally has a function as a normal terminal device.

  The radio communication unit 401 transmits a radio signal to the base station apparatus and receives a radio signal from the base station apparatus. For example, the wireless communication unit 401 can receive a signal including information on the difference value as described above. Here, the difference value information may be included in, for example, a physical downlink control channel (PDCCH) or may be included in a physical downlink shared channel (PDSCH). In addition, when the information of the difference value common to a plurality of terminal apparatuses is notified, the information of the difference value may be included in a broadcast signal such as SIB (System Information Block). Further, the wireless communication unit 401 can transmit an uplink signal including HARQ-ACK. In addition, the wireless communication unit 401 transmits a data signal based on not only HARQ-ACK but also a transmission schedule (uplink grant) specified by the base station apparatus, and receives HARQ-ACK for the data signal from the base station apparatus. You can also

  The resource specifying unit 402 acquires the above-described difference value information via the wireless communication unit 401. Then, the resource specifying unit 402 specifies the resource used when transmitting the HARQ-ACK from the acquired difference value information and the CCE position (first index) in the PDCCH when the base station apparatus transmits data. . That is, the resource specifying unit 402 specifies the resource index when the RRT is 4 milliseconds based on the head index of the CCE addressed to itself in the PDCCH, and adds the difference value notified to the index. Then, the resource specifying unit 402 specifies the addition result as an index corresponding to the resource that is actually used. The information of the identified resource is transferred to the retransmission control unit 403.

  The retransmission control unit 403 determines whether the data signal received from the base station device via the wireless communication unit 401 has been successfully received, and sends an acknowledgment (HARQ-ACK) via the wireless communication unit 401 to the base station. Send to device. The retransmission control unit 403 uses the resource (frequency position and code) specified by the resource specifying unit 402 when transmitting the confirmation response. Here, the resource for transmitting the acknowledgment may be a resource in the physical uplink control channel (PUCCH), but may be a resource other than the PUCCH. In addition, resources that can be used for PUCCHs that have been defined in the past may be expanded, and PUCCHs including acknowledgments may be transmitted over a wider range of resources.

(Process flow)
Subsequently, a flow of processing executed in the wireless communication system of the present embodiment will be described with reference to FIG. First, the base station apparatus transmits a data signal including resource designation information (the above-described difference value information) (S501). Here, in this example, it is assumed that the resource designation information is transmitted by PDCCH or PDSCH. Further, the base station apparatus may notify the resource designation information to each terminal apparatus in advance via a channel that is not PDCCH or PDSCH. Below, the example of the resource designation | designated method here is demonstrated using FIGS. 6-9. In the wireless communication system, a plurality of methods such as the methods shown in FIGS. 6 to 9 described below can be selectively used, and the base station apparatus uses any method for the resource designation information in S501. Can be sent including information on whether or not

  First, the example of FIGS. 6 and 7 will be described. In the example of FIGS. 6 and 7, it is assumed that there are terminal devices with HARQ RTTs of 2 milliseconds, 3 milliseconds, and 4 milliseconds, and the transmission timings of the HARQ-ACK match. However, for example, there may be a terminal device having an RTT of 1 millisecond, or a terminal device having an RTT of 5 milliseconds or more. Even in these cases, the following processing can be similarly applied.

  In the example of FIG. 6, PDCCH and PDSCH transmitted in the downlink and corresponding HARQ-ACK transmission resources are shown to correspond by being filled with the same pattern. That is, the terminal apparatus with an RTT of 4 milliseconds receives PDSCH in the leftmost subframe in FIG. 6 and transmits HARQ-ACK in the second resource from the bottom of the rightmost subframe. Here, this resource is specified from the head index of the CCE addressed to the terminal device included in the PDCCH received together with the PDSCH.

  In addition, in FIG. 6, the terminal apparatus with an RTT of 3 milliseconds receives PDSCH in the second subframe from the left in FIG. 6 and transmits HARQ-ACK in the fifth resource from the bottom of the rightmost subframe. Here, in FIG. 6, it is assumed that the value of the head index of the CCE for the terminal device having an RTT of 4 milliseconds and the terminal device having an RTT of 3 milliseconds are the same. Therefore, when a terminal device with an RTT of 3 milliseconds specifies a resource index from the top index of a CCE addressed to the terminal device according to the conventional method, resource contention occurs. For this reason, a terminal device with an RTT of 3 milliseconds specifies a resource index from the top index of the CCE addressed to the terminal device according to the conventional method, and further adds the difference value notified from the base station device to the specified value. By adding, the resource to be used is specified. Here, it is assumed that the index specified by the terminal device having an RTT of 3 milliseconds from the first index of the CCE is “2”, and the difference value notified to the terminal device is “3”. For this reason, the terminal apparatus specifies a resource (5th resource from the bottom) having 2 + 3 = 5 as an index as a resource for transmitting the HARQ-ACK.

  In addition, in FIG. 6, the terminal apparatus with an RTT of 2 milliseconds receives PDSCH in the third subframe from the left in FIG. 6 and transmits HARQ-ACK in the seventh resource from the bottom of the rightmost subframe. The resource here can also be specified in the same manner as in the case of a terminal device having an RTT of 3 milliseconds. Here, the difference value is “−2”, and the index value of the resource specified from the first index of the CCE is 9 (the ninth resource from the bottom). Therefore, the terminal device with an RTT of 2 milliseconds adds the notified difference value “−2” to the index value 9 specified from the top index of the CCE, and the index value is 7 as a resource to be actually used. Resource (the seventh resource from the bottom) can be specified.

  In this way, the base station apparatus, based on the RTT value used by each terminal apparatus, the difference value between the index of the resource used when the RTT is 4 milliseconds and the index of the resource to be actually used Is reported as an index shift amount in the terminal device. The terminal device can identify the resource for transmitting the HARQ-ACK by shifting the resource index determined according to the head index of the CCE according to the designated shift amount.

  In the example of FIG. 6, an example is shown in which the HARQ-ACK transmission resource is selected within the range of the resource index value range to be used when the RTT is 4 milliseconds. That is, in FIG. 6, a region surrounded by a thick line indicates a range of a resource index value range to be used when RTT is 4 milliseconds, and resources used by each terminal apparatus for transmission of HARQ-ACK Was set to be within the scope of this region. In addition, since the area surrounded by the thick line is determined according to the total number of CCE indexes, the value range is not always constant.

  On the other hand, FIG. 7 shows an example in which HARQ-ACK transmission resources are selected in a range other than the range of the resource index to be used when RTT is 4 milliseconds. In FIG. 7, the downlink transmission state is assumed to be the same as in FIG. 6, and the PDCCH and PDSCH in FIG. 6 and the HARQ-ACK transmission resources in FIG. 7 are filled with the same pattern. Is shown to correspond.

  In the case of the example in FIG. 7, the base station apparatus does not allocate resources that may be used when the RTT is 4 milliseconds to each terminal apparatus whose RTT is not 4 milliseconds. Allocate resources. Therefore, the base station apparatus is configured such that the index of the resource used by each terminal apparatus whose RTT is not 4 milliseconds for HARQ-ACK transmission belongs to a range other than the index range when the RTT is 4 milliseconds. Set the resource to be used. Then, the base station device specifies the difference value between the set value and the index when the RTT is 4 milliseconds as the designated shift amount, and notifies the terminal device. In the example of FIG. 7, the shift amount “8” is notified to the terminal device having an RTT of 3 milliseconds, and the shift amount “2” is notified to the terminal device having an RTT of 2 milliseconds. Is shown. By doing in this way, the resource for HARQ-ACK which the terminal device whose RTT is not 4 milliseconds transmits, and the HARQ-ACK which the terminal device whose RTT is 4 milliseconds, especially the conventional terminal device transmits It is possible to easily prevent contention with resources.

  In the example of FIGS. 6 and 7, the case where the base station apparatus directly notifies the shift amount has been described. On the other hand, in the examples of FIGS. 8 and 9, the base station apparatus notifies the terminal apparatus of a value that allows the terminal apparatus to calculate the shift amount.

  In the example of FIG. 8, the base station apparatus notifies the terminal apparatus of the total number of CCEs set in each subframe. Here, it is assumed that HARQ-ACK is transmitted in the j + 4th subframe. That is, a terminal device with an RTT of 1 ms receives PDSCH in the j + 3th subframe, and a terminal device with an RTT of 2 ms and 3 ms receives the PDSCH in the j + 2 and j + 1th subframes, respectively. It shall be received. Similarly, in the j-th subframe, it is assumed that a terminal device having an RTT of 4 milliseconds receives PDSCH. Here, it is assumed that the numbers of CCEs notified from the base station apparatus are 25, 41, and 8 in the j, j + 1, and j + 2 subframes, respectively.

  At this time, it is assumed that the index of the resource used by the terminal device having an RTT of 4 milliseconds starts from the minimum value, and the index value increases toward the index of the resource used by the terminal device having a shorter RTT. . That is, in this example, it is assumed that the index value is set so that the index value used by the terminal device having an RRT of 1 millisecond is the largest. Here, as described above, the value range of the index of the resource is determined according to the set number of CCEs. Therefore, in order to arrange the index ranges corresponding to each of the plurality of RRTs so as not to overlap, it is only necessary to shift the index by the total number of CCEs. That is, in the example of FIG. 8, since the total number of CCEs in the j-th subframe is 25, the width of the resource index value range used by the terminal device with an RRT of 4 milliseconds is 25. For this reason, the terminal apparatus with an RRT of 3 milliseconds shifts the index of resources for use in HARQ-ACK by the total number of CCEs “25” in the j-th subframe. Next, since the total number of CCEs in the j-th subframe is 41, the width of the resource index value range used by the terminal device having an RRT of 3 milliseconds is 41. Here, the resource index used by the terminal device with an RRT of 3 milliseconds is shifted by 25 as described above. For this reason, the terminal device having an RRT of 2 milliseconds uses the index of resources for use in HARQ-ACK as the total number of CCEs “25” in the j-th subframe and the total number of CCEs “41” in the j + 1-th subframe. "66" which is the sum of "". Similarly, a terminal device with an RRT of 1 millisecond uses a sum of “25”, “41”, and “8”, which is the total number of CCEs in the jth to j + second subframes, for the resource index to be used in HARQ-ACK. Is shifted by “74”. As described above, the terminal apparatus determines the shift amount of the resource index used for HARQ-ACK transmission according to the total number of CCEs set in each subframe and the RTT used by itself. Thereby, a plurality of terminal devices using different RTTs do not transmit HARQ-ACK using the same resource.

  In the example of FIG. 9, instead of the total number of CCEs, the number of OFDM symbols used for PDCCH transmission is notified to the terminal apparatus. Here, the number of OFDM symbols used for PDCCH transmission roughly corresponds to the number of CCEs set above. For example, when the number of OFDM symbols is 1, the number of CCEs is 9, when the number of OFDM symbols is 2, the number of CCEs is 25, and when the number of OFDM symbols is 3, the number of CCEs is 41. Therefore, the terminal device can shift the resource index similarly to the example of FIG. 8 by knowing the number of OFDM symbols used for transmission of these PDCCHs.

  The terminal device can know the number of OFDM symbols used for PDCCH transmission in each subframe by observing the conventional PCFICH. On the other hand, the base station apparatus may notify the total number of OFDM symbols used for transmission of the PDCCH over a predetermined period corresponding to the RTT according to the RTT of each terminal apparatus. That is, as in the example of FIG. 9, information on the number of OFDM symbols corresponding to the RTT value used by the terminal apparatus is notified to the terminal apparatus that transmits HARQ-ACK at j + 4. For example, the number of OFDM symbols “2” used for PDCCH transmission is reported in the j-th subframe to a terminal device with an RTT of 3 milliseconds. On the other hand, a terminal device with an RTT of 2 milliseconds is notified of “5” that is the sum of the number of OFDM symbols “2” and “3” used for PDCCH transmission in the j-th and j + 1-th subframes. The Similarly, for a terminal device with an RTT of 1 ms, “6”, which is the sum of the number of OFDM symbols “2”, “3”, and “1” used for PDCCH transmission in the j to j + 2nd subframes. Will be notified. Note that the base station apparatus may notify the number of OFDM symbols in each subframe instead of such a sum.

  When the terminal apparatus receives information on the number of OFDM symbols, the terminal apparatus specifies a shift amount of an index of resources used for transmission of HARQ-ACK based on the information. This specific method can include converting the number of OFDM symbols into the number of CCEs that can be set, and the terminal apparatus specifies the shift amount of the index of the resource as shown in FIG. 8 from this conversion result. be able to. Note that, as described above, when the sum of the number of OFDM symbols used for PDCCH transmission is notified in a plurality of subframes, the terminal apparatus determines the maximum of the total number of CCEs that can be specified according to the sum. The value can be used as a shift amount. For example, in the example of FIG. 9, a value of “6” is notified to a terminal device having an RRT of 1 millisecond. Here, the number of OFDM symbols for PDCCH transmission for each subframe is set between 1 and 3. At this time, the combination using 6 OFDM symbols in 3 subframes is the case where “2” OFDM symbols are used in each subframe, or “1”, “2”, and “3” in 3 subframes, respectively. Of OFDM symbols are used. In the former case, the total number of corresponding CCEs is “75”, and in the latter case, the total number of corresponding CCEs is “74”. Therefore, in this case, the terminal device can specify “75” as the shift amount. Thereby, a plurality of terminal devices using different RTTs do not transmit HARQ-ACK using the same resource.

  Returning to FIG. 5, the terminal device transmits HARQ-ACK as described with reference to FIGS. 6 to 9 based on the head index of the CCE addressed to itself and the information notified from the base station device. The resource used at the time is specified (S502). Then, the terminal apparatus transmits HARQ-ACK to the base station apparatus using the specified resource (S503).

  In this way, even when a device on the data signal receiving side (terminal device in the above example) transmits HARQ-ACK with various RTTs, resources used for HARQ-ACK may compete. Disappear. As a result, the device on the data signal transmission side (base station device in the above example) can correctly receive the confirmation response, and it is possible to prevent deterioration in efficiency of retransmission control.

  Note that the resource designation information may be notified from the base station apparatus to the terminal apparatus by RRC (Radio Resource Control) signaling at the time of establishing a connection, for example. When common resource related information is used for a plurality of terminal devices, the resource related information may be notified by broadcasting.

  The typical configuration and the flow of processing according to the present embodiment have been described above. However, these are merely examples, and various modifications to the embodiments described in the present specification can be made within the scope described in the claims. Various modifications and changes are naturally included in the scope of the present invention.

Claims (15)

A base station device capable of transmitting a signal to a terminal device and receiving an acknowledgment from the terminal device,
A setting unit configured to set a resource to be used for transmitting the confirmation response based on a length of a period from when the terminal device receives the signal until the confirmation response is transmitted;
Transmitting means for transmitting information specifying a set resource to the terminal device;
Receiving means for receiving the acknowledgment sent by the terminal device using a set resource;
Have
A plurality of resources that can be used for transmitting the confirmation response are associated with different indexes,
The transmission unit transmits, as the information, a value related to a difference value between a resource index value set by the setting unit and a resource index value used when the length of the period is a predetermined length. To
A base station apparatus. The setting means sets a resource to be used by the terminal device to transmit the confirmation response within a range of a value of a resource index used when the length of the period is the predetermined length.
The base station apparatus according to claim 1. The setting means, with respect to the terminal device whose length of the period is not the predetermined length, in a range other than the range of the value of the resource index used when the length of the period is the predetermined length, Setting a resource to be used for sending the acknowledgment;
The base station apparatus according to claim 1. The transmission means does not transmit the information to the terminal device having the predetermined period.
The base station apparatus according to claim 1, wherein the base station apparatus is a base station apparatus. The value related to the difference value is a value related to the total number of control information transmitted from the base station apparatus a predetermined period before the timing at which the terminal apparatus transmits the confirmation response.
The base station apparatus according to claim 1, wherein the base station apparatus is a base station apparatus. The predetermined period has a length corresponding to a difference between the predetermined length and the length of the period.
The base station apparatus according to claim 5. The transmission means transmits a value related to the total number to the terminal device according to the number of symbols used for transmission of the control information.
The base station apparatus according to claim 5 or 6, wherein A terminal device that can receive a signal from a base station device and transmit an acknowledgment to the base station device after a predetermined period,
Receiving means for receiving, from the base station apparatus, information specifying the resource that the terminal apparatus should use for transmitting the confirmation response;
A specifying means for specifying a resource for transmitting the confirmation response based on the information;
Transmitting means for transmitting the acknowledgment using the identified resource;
Have
A plurality of resources that can be used for transmitting the confirmation response are associated with different indexes,
The information includes a value of an index of a resource to be used when the terminal device receives the signal and transmits the confirmation response to the base station device after the predetermined period, and the information from the base station device. Including a value related to a difference value from a value of a resource index used when a length of a period from reception of a signal to transmission of the confirmation response is a predetermined length,
The specifying means includes the difference value and a value of a resource index used when a length of a period from reception of the signal from the base station apparatus to transmission of the confirmation response is a predetermined length. Identifying a resource for transmitting the confirmation response after the predetermined period after receiving the signal from the base station device;
A terminal device characterized by that. The specifying unit adds the difference value to a value of a resource index used when a length of a period from reception of the signal from the base station apparatus to transmission of the confirmation response is a predetermined length. An index specifies a resource for transmitting the confirmation response after the predetermined period after receiving the signal from the base station device,
The terminal device according to claim 8. The value related to the difference value is a value related to the total number of control information transmitted from the base station apparatus a predetermined period before the timing at which the terminal apparatus transmits the confirmation response.
The terminal device according to claim 8 or 9, wherein The specifying means specifies a value related to the total number according to the number of symbols used for transmission of the control information.
The terminal device according to claim 10. A communication method of a base station apparatus that can transmit a signal to a terminal apparatus and receive an acknowledgment from the terminal apparatus,
A setting step in which a setting unit sets a resource to be used by the terminal device to transmit the confirmation response based on a length of a period from when the terminal device receives the signal to when the confirmation response is transmitted; ,
A transmission step in which the transmission means transmits information specifying the set resource to the terminal device;
A reception step of receiving the confirmation response transmitted by the receiving means using the resource set by the terminal device;
Have
A plurality of resources that can be used for transmitting the confirmation response are associated with different indexes,
In the transmission step, a value related to a difference value between the resource index value set in the setting step and the resource index value used when the length of the period is a predetermined length is transmitted as the information. To
A communication method characterized by the above. A communication method of a terminal device that can receive a signal from a base station device and transmit an acknowledgment to the base station device after a predetermined period,
A receiving step for receiving, from the base station device, information specifying a resource that the terminal device should use for transmitting the confirmation response;
A specifying step in which a specifying unit specifies a resource for transmitting the confirmation response based on the information;
A transmitting step in which the transmitting means transmits the confirmation response using the identified resource;
Have
A plurality of resources that can be used for transmitting the confirmation response are associated with different indexes,
The information includes a value of an index of a resource to be used when the terminal device receives the signal and transmits the confirmation response to the base station device after the predetermined period, and the information from the base station device. Including a value related to a difference value from a value of a resource index used when a length of a period from reception of a signal to transmission of the confirmation response is a predetermined length,
In the specifying step, from the difference value and a value of a resource index used when a length of a period from reception of the signal from the base station apparatus to transmission of the confirmation response is a predetermined length Identifying a resource for transmitting the confirmation response after the predetermined period after receiving the signal from the base station device;
A communication method characterized by the above. A computer provided in a base station device that can transmit a signal to a terminal device and receive an acknowledgment from the terminal device,
A setting step of setting a resource to be used for transmission of the confirmation response based on a length of a period from when the terminal device receives the signal to transmission of the confirmation response;
A transmission step of transmitting information specifying a set resource to the terminal device;
A receiving step of receiving the confirmation response transmitted by the terminal device using a set resource;
A program for executing
A plurality of resources that can be used for transmitting the confirmation response are associated with different indexes,
In the transmission step, a value related to a difference value between the resource index value set in the setting step and the resource index value used when the length of the period is a predetermined length is transmitted as the information. To
A program characterized by that. A computer provided in a terminal device that receives a signal from a base station device and can transmit an acknowledgment to the base station device after a predetermined period,
Receiving from the base station device information specifying the resource to be used by the terminal device to transmit the confirmation response;
A specific step of identifying a resource when transmitting the confirmation response based on the information;
A transmitting step of transmitting the acknowledgment using the identified resource;
A program for executing
A plurality of resources that can be used for transmitting the confirmation response are associated with different indexes,
The information includes a value of an index of a resource to be used when the terminal device receives the signal and transmits the confirmation response to the base station device after the predetermined period, and the information from the base station device. Including a value related to a difference value from a value of a resource index used when a length of a period from reception of a signal to transmission of the confirmation response is a predetermined length,
In the specifying step, from the difference value and a value of a resource index used when a length of a period from reception of the signal from the base station apparatus to transmission of the confirmation response is a predetermined length Identifying a resource for transmitting the confirmation response after the predetermined period after receiving the signal from the base station device;
A program characterized by that.

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