HK1250190B - Terminal device, communication device, communication method, and integrated circuit - Google Patents

Description

Terminal device, communication device, communication method, and integrated circuit

This application is a divisional application of the invention patent application with an international filing date of June 11, 2013, application number 201380031401.7, and invention name “Terminal device and buffer partitioning method”.

Technical Field

The present invention relates to a terminal device and a buffer zone partitioning method.

Background Art

3GPP LTE uses OFDMA (Orthogonal Frequency Division Multiple Access) as the downlink communication method. In a wireless communication system using 3GPP LTE, the base station uses predetermined communication resources to transmit synchronization signals (Synchronization Channel: SCH) and broadcast signals (Broadcast Channel: BCH). Furthermore, the terminal first synchronizes with the base station by acquiring the SCH. The terminal then obtains base station-specific parameters (such as bandwidth) by reading the BCH information (see Non-Patent Documents 1, 2, and 3).

After acquiring base station-specific parameters, the terminal establishes communication with the base station by sending a connection request to the base station. The base station sends control information to the terminal with which communication has been established via downlink control channels such as the PDCCH (Physical Downlink Control Channel), as needed.

Then, the terminal performs "blind judgment" on each of the multiple control information (downlink assignment control information: DL Assignment (sometimes also called downlink control information: Downlink Control Information: DCI)) contained in the received PDCCH signal. In other words, the control information includes a CRC (Cyclic Redundancy Check) part, and the base station uses the terminal ID of the sending terminal to mask the CRC part. Therefore, the terminal cannot determine whether the control information is sent to the terminal before trying to demask the CRC part of the received control information using the terminal ID of the terminal. In this blind judgment, if the CRC calculation result of the demasking is OK, it is determined that the control information is sent to the terminal.

Furthermore, in 3GPP LTE, ARQ (Automatic Repeat Request) is applied to downlink data sent from a base station to a terminal. Specifically, the terminal feeds back a response signal indicating the error detection result of the downlink data to the base station. The terminal performs a CRC on the downlink data. If the CRC is OK (error-free), an ACK (acknowledgement) is fed back to the base station as a response signal. If the CRC is NG (error present), a NACK (non-acknowledgement) is fed back to the base station as a response signal. This response signal (i.e., ACK/NACK signal, sometimes referred to as "A/N" below) is fed back using an uplink control channel such as the PUCCH (Physical Uplink Control Channel).

The control information transmitted from the base station includes resource allocation information, including information about the resources allocated by the base station to the terminal. As mentioned above, the PDCCH is used to transmit this control information. The PDCCH consists of one or more L1/L2CCHs (L1/L2 Control Channels). Each L1/L2CCH consists of one or more CCEs (Control Channel Elements). In other words, a CCE is the basic unit for mapping control information onto the PDCCH. Furthermore, when an L1/L2CCH consists of multiple (2, 4, or 8) CCEs, a continuous sequence of CCEs starting with a CCE with an even-numbered index is allocated to the L1/L2CCH. The base station allocates an L1/L2CCH to the terminal to which the resource is allocated, based on the number of CCEs required to notify the terminal of the control information. The base station then maps the control information onto the physical resources corresponding to the CCEs of the L1/L2CCH and transmits it.

In addition, here, each CCE is associated one-to-one with a PUCCH constituent resource (hereinafter sometimes referred to as a PUCCH resource). Therefore, a terminal receiving an L1/L2CCH determines the PUCCH constituent resource corresponding to the CCE constituting the L1/L2CCH and uses this resource to send a response signal to the base station. However, when the L1/L2CCH occupies multiple consecutive CCEs, the terminal uses the PUCCH constituent resource corresponding to the CCE with the smallest index among the multiple PUCCH constituent resources corresponding to the multiple CCEs (i.e., the PUCCH constituent resource associated with the CCE with an even-numbered CCE index) to send the response signal to the base station. In this way, downlink communication resources are used efficiently.

As shown in Figure 1, multiple response signals transmitted from multiple terminals are spread on the time axis using a ZAC (Zero Auto-Correlation) sequence with zero auto-correlation characteristics, a Walsh sequence, and a DFT (Discrete Fourier Transform) sequence, and code-multiplexed within the PUCCH. In Figure 1, (W ₀ , W ₁ , W ₂ , W ₃ ) represent a Walsh sequence with a sequence length of 4, and (F ₀ , F ₁ , F ₂ ) represent a DFT sequence with a sequence length of 3. As shown in Figure 1, at the terminal, the ACK or NACK response signal is first spread on the frequency axis using a ZAC sequence (sequence length of 12) into frequency components corresponding to one SC-FDMA symbol. That is, the response signal components represented by complex numbers are multiplied by the ZAC sequence with a sequence length of 12. Next, the response signal after primary spreading and the ZAC sequence serving as the reference signal are secondary spread, corresponding to the Walsh sequence (sequence length of 4: W ₀ to W ₃ , sometimes also called the Walsh Code Sequence) and the DFT sequence (sequence length of 3: F ₀ to F ₂ ). Specifically, each component of the signal with a sequence length of 12 (the response signal after primary spreading or the ZAC sequence serving as the reference signal) is multiplied by each component of the orthogonal code sequence (Walsh sequence or DFT sequence). Furthermore, the secondary spread signal is transformed into a signal with a sequence length of 12 on the time axis using an Inverse Fast Fourier Transform (IFFT). A CP is then added to each of the IFFT signals, forming a single-slot signal consisting of seven SC-FDMA symbols.

Response signals from different terminals are spread using ZAC sequences corresponding to different cyclic shift indices (Cyclic Shift Indexes) or orthogonal code sequences corresponding to different sequence numbers (Orthogonal Cover Indexes: OC indices). An orthogonal code sequence is a combination of a Walsh sequence and a DFT sequence. Furthermore, an orthogonal code sequence is sometimes also referred to as a block-wise spreading code sequence. Therefore, the base station can separate these multiple code-multiplexed response signals by using conventional despreading and correlation processing (see Non-Patent Document 4).

However, each terminal performs blind judgment on the downlink allocation control signal sent to its own device in each subframe, so the downlink allocation control signal may not be successfully received on the terminal side. When the terminal fails to receive the downlink allocation control signal sent to its own device in a certain downlink unit frequency band, the terminal cannot even know whether there is downlink link data sent to its own device in the downlink unit frequency band. Therefore, when the reception of the downlink allocation control signal in a certain downlink unit frequency band fails, the terminal does not generate a response signal for the downlink link data in the downlink unit frequency band. This error situation is defined as DTX (DTX (Discontinuous transmission) of ACK/NACK signals) of the response signal in the sense that the response signal is not sent on the terminal side.

Furthermore, in the 3GPP LTE system (hereinafter sometimes referred to as the "LTE system"), base stations independently allocate resources for uplink and downlink data. Therefore, in the LTE system, in the uplink, a terminal (i.e., a terminal that applies the LTE system (hereinafter referred to as an "LTE terminal")) may need to simultaneously transmit a response signal to downlink data and uplink data. In this case, time division multiplexing (TDM) is used to transmit the response signal from the terminal and the uplink data. By using TDM to simultaneously transmit the response signal and uplink data, the single-carrier properties of the terminal's transmission waveform are maintained.

In addition, as shown in FIG2 , in time division multiplexing (TDM), the response signal ("A/N") transmitted from the terminal occupies a portion of the resources (PUSCH (Physical Uplink Shared CHannel) resources) allocated for uplink data (a portion of the SC-FDMA symbol adjacent to the SC-FDMA symbol mapped with the reference signal (RS (Reference Signal))) and is transmitted to the base station. The "subcarrier" on the vertical axis in FIG2 is sometimes also referred to as a "virtual subcarrier" or a "time contiguous signal." For convenience, the "time-contiguous signal" that is aggregated and input to the DFT (Discrete Fourier Transform) circuit in the SC-FDMA transmitter is represented as a "subcarrier." That is, in the PUSCH resource, arbitrary data in the uplink data is punctured due to the response signal. Therefore, since arbitrary bits of the coded uplink data are punctured, the quality of the uplink data (e.g., coding gain) is significantly degraded. Therefore, the base station compensates for the quality degradation of uplink data caused by puncturing by, for example, instructing the terminal to use a very low coding rate or to use a very high transmission power.

Furthermore, standardization of 3GPP LTE-Advanced (3GPP LTE-Advanced), designed to achieve even higher-speed communications than 3GPP LTE, is underway. The 3GPP LTE-Advanced system (hereinafter sometimes referred to as the "LTE-A" system) is a successor to the LTE system. To achieve a maximum downlink transmission speed of 1 Gbps or higher, 3GPP LTE-Advanced introduces base stations and terminals capable of communicating at a wideband frequency of 40 MHz or higher.

In the LTE-A system, in order to simultaneously achieve communication based on ultra-high-speed transmission speeds several times that of the LTE system and backward compatibility with the LTE system, the frequency band used for the LTE-A system is divided into "unit bands" of less than 20 MHz, which are the supported bandwidth of the LTE system. That is, here, the "unit band" is a frequency band with a maximum width of 20 MHz, which is defined as the basic unit of the communication frequency band. In the FDD (Frequency Division Duplex) system, the "unit band" in the downlink line (hereinafter referred to as the "downlink unit band") is sometimes defined as a frequency band divided based on the downlink frequency band information in the BCH notified from the base station, or a frequency band defined by the distribution width when the downlink control channel (PDCCH) is distributed in the frequency domain. In addition, the "unit band" in the uplink (hereinafter referred to as "uplink unit band") is sometimes defined as a band divided based on the uplink band information in the BCH notified from the base station, or as a basic unit of the communication band below 20 MHz, containing the PUSCH (Physical Uplink Shared Channel) area near the center and the PUCCH used for LTE at both ends. Furthermore, in 3GPP LTE-Advanced, "unit band" is sometimes referred to in English as "Component Carrier(s)" or "Cell." It is also sometimes referred to as CC(s) as an abbreviation.

In a TDD (Time Division Duplex) system, the downlink component band and the uplink component band are the same frequency band, and downlink and uplink communications are achieved by switching the downlink and uplink lines in a time-division manner. Therefore, in the case of a TDD system, the downlink component band can also be expressed as "downlink communication timing in the unit band." The uplink component band can also be expressed as "uplink communication timing in the unit band." As shown in Figure 3, the switching between the downlink component band and the uplink component band is based on the UL-DL Configuration. It is assumed that the UL-DL Configuration is notified to the terminal through a broadcast signal called SIB1 (System Information Block Type 1), and its value is the same throughout the entire system and is not frequently changed. In the UL-DL Configuration shown in Figure 3, the timing of downlink communication (DL: Downlink) and uplink communication (UL: Uplink) is set in subframe units (i.e., 1 millisecond units) for every 1 frame (10 milliseconds). In the UL-DL Configuration, by changing the subframe ratio of downlink communication and uplink communication, a communication system that can flexibly respond to the requirements of the throughput of downlink communication and the throughput of uplink communication can be constructed. For example, Figure 3 shows a UL-DL Configuration (Config#0~6) with different subframe ratios of downlink communication and uplink communication. In addition, in Figure 3, "D" represents the downlink communication subframe, "U" represents the uplink communication subframe, and "S" represents the special (Special) subframe. Here, the special subframe is the subframe when switching from the downlink communication subframe to the uplink communication subframe. In addition, in the special subframe, downlink data communication is sometimes performed in the same way as the downlink communication subframe. In addition, in each UL-DL Configuration shown in Figure 3, the subframes of 2 frames (20 subframes) are divided into subframes for downlink communication ("D" and "S" in the upper section) and subframes for uplink communication ("U" in the lower section), and are represented in two sections. Furthermore, as shown in FIG3 , the error detection result (ACK/NACK) of the downlink data is notified in an uplink communication subframe that is four or more subframes after the subframe to which the downlink data is allocated.

In addition, in the LTE-A system, a scheme for changing the UL-DL Configuration (hereinafter sometimes referred to as TDD eIMTA (enhancement for DL-UL Interference Management and Traffic Adaptation)) is being studied. The purpose of TDD eIMTA can be to provide services that meet user needs by flexibly changing the UL/DL ratio, or to reduce base station power consumption by increasing the UL ratio in time bands with low traffic load. As methods for changing the UL-DL Configuration, the following methods are being studied according to the purpose of the change: (1) a notification method based on SI (System Information) signaling, (2) a notification method based on RRC (higher layer) signaling, and (3) a notification method based on L1 (Physical Layer) signaling.

Method (1) is the least frequent change of UL-DL Configuration. Method (1) is applicable, for example, to the case where the purpose is to reduce the power consumption of the base station by increasing the UL ratio during a period of low traffic load (e.g., late at night or early in the morning). Method (3) is the most frequent change of UL-DL Configuration. In a smaller cell such as a picocell, the number of connected terminals is small compared to a larger cell such as a macrocell. In a picocell, the UL/DL traffic volume of the entire picocell is determined based on the amount of UL/DL traffic in the small number of terminals connected to the picocell. Therefore, in a picocell, the temporal variation of the UL/DL traffic volume is drastic. Therefore, in the case of changing the UL-DL Configuration in accordance with the temporal variation of the UL/DL traffic volume in a smaller cell such as a picocell, method (3) is most suitable. Method (2) is between method (1) and method (3) and is suitable for the case where the frequency of UL-DL Configuration changes is moderate.

In addition, the LTE system and the LTE-A system support HARQ (Hybrid Automatic Repeat reQuest) for downlink data (hereinafter referred to as "DL HARQ"). In DL HARQ, LTE terminals and LTE-A terminals store the LLRs (Log Likelihood Ratios) (or sometimes also referred to as soft bits) of downlink data in which errors have been detected in a soft buffer. The LLRs stored in the soft buffer are synthesized with the LLRs of the downlink data to be retransmitted (retransmission data). As shown in FIG4 and the following equation (1), the soft buffer (buffer capacity: N _soft ) is divided equally based on the number of downlink component bands (K _C ) supported by the terminal, the number of multiplexing layers (K _MIMO ) supported by the terminal, and the maximum number of DL HARQ processes (M _{DL_HARQ} ) specified by the UL-DL Configuration set for the terminal, and the IR (Incremental Redundancy) buffer size (N _IR ) is calculated for each transport block (or TB). In addition, the maximum number of DL HARQ processes represents the number of retransmission processes (number of DL HARQ processes) set based on the maximum value of the retransmission interval (sometimes also referred to as RTT (Round Trip Time)) from the transmission of downlink data to the retransmission of the downlink data in each UL-DL Configuration (Config#0 to #6) of DL HARQ (refer to Figure 5).

In addition, as shown in FIG5 , for each UL-DL Configuration, the maximum number of DL HARQ processes has different values.

The terminal stores the LLRs of the downlink data in which errors are detected in the IR buffer corresponding to each DL HARQ process within the range of the IR buffer size per 1TB calculated by equation (1). Here, M _limit shown in equation (1) is the allowable value that the terminal can handle for the number of DL HARQ processes stored in the soft buffer, for example, the value of M _limit is 8. In addition, in order to suppress the total capacity of the soft buffer (soft buffer capacity), each 1TB IR buffer does not necessarily store all the system check bits (LLRs) and all the parity check bits (LLRs) per 1TB. Therefore, increasing the IR buffer size per 1TB as much as possible within the limited soft buffer capacity will increase the total amount of LLRs that can be stored in the IR buffer, thereby improving the HARQ retransmission performance.

Prior art literature

Non-patent literature

Non-patent document 1: 3GPP TS 36.211 V10.1.0, “Physical Channels and Modulation (Release 10),” March 2011

Non-Patent Document 2: 3GPP TS 36.212 V10.1.0, “Multiplexing and channel coding (Release 10),” March 2011

Non-Patent Document 3: 3GPP TS 36.213 V10.1.0, “Physical layer procedures (Release 10),” March 2011

Non-patent document 4: Seigo Nakao, Tomofumi Takata, Daichi Imamura, and Katsuhiko Hiramatsu, "Performance enhancement of E-UTRA uplink control channel in fastfading environments," Proceeding of IEEE VTC 2009 spring, April.2009

Summary of the Invention

Problems to be solved by the invention

If different UL-DL configurations are set between terminals supporting TDD eIMTA, interference between uplink communications and downlink communications (hereinafter sometimes referred to as "UL-DL interference") occurs between the terminals. To avoid the occurrence of this UL-DL interference, in terminals supporting TDD eIMTA, the UL-DL configuration is changed for each cell (Cellspecific) rather than for each terminal (UE-specific).

When the UL-DL Configuration is changed for each cell, most terminals supporting TDD eIMTA are likely to change the UL-DL Configuration when all DL HARQ processes are not completed (ie, ACK is not sent back to the base station).

In addition, as shown in Figure 5, the maximum number of DL HARQ processes (MDL_HARQ) varies between different UL-DL Configurations. Therefore, if the maximum number of DL HARQ processes for at least one of the UL-DL Configurations before and after the change is less than 8, the IR buffer size per 1TB also varies before and after the change of the UL-DL Configuration.

For example, as shown in FIG6 , when the configuration is changed from Config#0 to Config#1, the maximum number of DL HARQ processes changes from 4 processes to 7 processes. In this case, as shown in FIG6 , the number of soft buffer partitions before and after the UL-DL Configuration change is also different, and thus the data reference position on the soft buffer before and after the UL-DL Configuration change is different. Therefore, the terminal cannot correctly read the stored data and cannot continue DL HARQ before and after the UL-DL Configuration change. In other words, there is a concern that the HARQ retransmission performance before and after the UL-DL Configuration change may deteriorate. The degradation of the HARQ retransmission performance may also occur in the case of low or medium frequency UL-DL Configuration changes such as the above-mentioned UL-DL Configuration change method (1) or method (2), but it is more significant when the UL-DL Configuration is changed at a high frequency such as method (3).

The object of the present invention is to provide a terminal device and a buffer partitioning method capable of suppressing degradation of HARQ retransmission performance by continuing the DL HARQ process for downlink data before and after a change in UL-DL Configuration (ratio of UL subframes to DL subframes).

Solutions to the Problem

A terminal device according to one embodiment of the present invention includes: a receiving unit for receiving information sent by a higher layer, wherein the information represents an uplink/downlink configuration that can be set relative to the terminal device and can be changed in enhanced downlink-uplink interference management and service adaptation, among a plurality of uplink/downlink configurations that define the structure of a downlink subframe and an uplink subframe in one frame; and a decoding unit for storing received data in a soft buffer having a size per transmission block, wherein the size of each transmission block is calculated based on the smaller value of the maximum value of the maximum number of hybrid automatic repeat request processes for the downlink of the uplink/downlink configuration that can be set and an allowable value.

A communication device according to one embodiment of the present invention includes: a setting unit for setting a configurable uplink/downlink configuration for calculating the soft buffer size for each transmission block in a terminal, wherein the uplink/downlink configuration is an uplink/downlink configuration that can be set relative to the terminal and can be changed in enhanced downlink-uplink interference management and service adaptation, among multiple uplink/downlink configurations that define the structure of the downlink link subframe and the uplink link subframe in one frame; and a sending unit for sending information representing the configurable uplink/downlink configuration by a higher layer, and calculating the soft buffer size for each transmission block based on the maximum value of the maximum number of hybrid automatic repeat request processes for the downlink of the configurable uplink/downlink configuration and the smaller value of the allowed value.

A communication method according to one embodiment of the present invention includes the following steps: a step of receiving information sent by a higher layer, wherein the information represents an uplink/downlink configuration that can be set relative to a terminal and can be changed in enhanced downlink-uplink interference management and service adaptation, among a plurality of uplink/downlink configurations that define the structure of a downlink subframe and an uplink subframe in one frame; and a step of storing received data in a soft buffer having a size per transmission block, wherein the size per transmission block is calculated based on the smaller value of the maximum value of the maximum number of hybrid automatic repeat request processes for the downlink of the uplink/downlink configuration that can be set and an allowable value.

A communication method according to one embodiment of the present invention includes the following steps: a step of setting a configurable uplink/downlink configuration for calculating the soft buffer size for each transmission block in a terminal, wherein the uplink/downlink configuration is an uplink/downlink configuration that can be set relative to the terminal and can be changed in enhanced downlink-uplink interference management and service adaptation, among multiple uplink/downlink configurations that define the structure of the downlink link subframe and the uplink link subframe in one frame; and a step of sending information representing the configurable uplink/downlink configuration by a higher layer, and calculating the soft buffer size for each transmission block based on the maximum value of the maximum number of hybrid automatic repeat request processes for the downlink of the configurable uplink/downlink configuration and the smaller value of the allowed value.

An integrated circuit of one embodiment of the present invention controls the following processing: a process of receiving information sent by a higher layer, wherein the information represents an uplink/downlink configuration that can be set relative to a terminal and can be changed in enhanced downlink-uplink interference management and service adaptation, among multiple uplink/downlink configurations that define the structure of a downlink subframe and an uplink subframe in one frame; and a process of storing received data in a soft buffer having a size per transmission block, wherein the size of each transmission block is calculated based on the smaller value of the maximum value of the maximum number of hybrid automatic repeat request processes for the downlink of the uplink/downlink configuration that can be set and an allowable value.

An integrated circuit of one embodiment of the present invention controls the following processing: a process of setting a configurable uplink/downlink configuration for calculating the soft buffer size for each transmission block in a terminal, wherein the uplink/downlink configuration is an uplink/downlink configuration that can be set relative to the terminal and can be changed in enhanced downlink-uplink interference management and service adaptation, among multiple uplink/downlink configurations that define the structure of the downlink link subframe and the uplink link subframe in one frame; and a process of sending information representing the configurable uplink/downlink configuration by a higher layer, calculating the soft buffer size for each transmission block based on the maximum value of the maximum number of hybrid automatic repeat request processes for the downlink of the configurable uplink/downlink configuration and the smaller value of the allowed value.

A terminal device according to one embodiment of the present invention is capable of setting and changing a configuration pattern of subframes constituting one frame, wherein the configuration pattern includes a downlink communication subframe for downlink communication and an uplink communication subframe for uplink communication, and the terminal device adopts a structure comprising: a decoding unit for storing downlink data sent from a base station device in a buffer for retransmission and decoding the downlink data; and a sending unit for sending a response signal generated using an error detection result of the downlink data, and dividing the buffer into a plurality of areas for each retransmission process based on a maximum value of the number of retransmission processes specified for a plurality of the configuration patterns that can be set for the terminal device.

A buffer partitioning method according to one embodiment of the present invention is used for a terminal device that can change the configuration pattern of subframes constituting one frame, wherein the configuration pattern includes a downlink communication subframe for downlink communication and an uplink communication subframe for uplink communication, and the buffer partitioning method comprises the following steps: a step of storing downlink data sent from a base station device in a buffer for retransmission; a step of decoding the downlink data; and a step of sending a response signal generated using an error detection result of the downlink data, wherein the buffer is divided into a plurality of areas for each retransmission process based on the maximum value of the number of retransmission processes specified for each of the plurality of configuration patterns that can be set for the terminal device.

Effects of the Invention

According to the present invention, degradation of HARQ retransmission performance can be suppressed by continuing the DL HARQ process for downlink data before and after the UL-DL Configuration (ratio of UL subframes to DL subframes) is changed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a diagram showing a spreading method for a response signal and a reference signal.

FIG2 is a diagram showing operations related to application of TDM to a response signal and uplink data in a PUSCH resource.

FIG3 is a diagram for explaining UL-DL Configuration in TDD.

FIG4 is a diagram for explaining calculation of the IR buffer size.

FIG5 is a diagram showing the maximum number of DL HARQ processes for UL-DL Configuration.

FIG6 is a diagram for explaining problems in changing the UL-DL Configuration.

FIG7 is a block diagram showing a main configuration of a terminal according to Embodiment 1 of the present invention.

FIG8 is a block diagram showing the configuration of a base station according to Embodiment 1 of the present invention.

FIG9 is a block diagram showing the configuration of a terminal according to Embodiment 1 of the present invention.

FIG10 is a diagram showing a method for dividing a soft buffer according to the first embodiment of the present invention.

FIG11 is a diagram showing a method for dividing a soft buffer according to the first embodiment of the present invention.

FIG12A is a diagram showing a method of utilizing the remaining IR buffer area according to the utilization method 1 of the second embodiment of the present invention.

FIG12B is a diagram showing a method of utilizing the remaining IR buffer area according to the second utilization method of the second embodiment of the present invention.

FIG. 13 is a diagram for explaining a problem in memory access according to the third embodiment of the present invention.

FIG. 14 is a diagram showing an example of a method of utilizing the remaining IR buffer area according to the third embodiment of the present invention.

FIG. 15 is a diagram showing an example of a method of utilizing the remaining IR buffer area according to the third embodiment of the present invention.

FIG. 16 is a diagram for explaining the effects of memory access according to the third embodiment of the present invention.

FIG. 17 is a diagram for explaining the concept of a simple memory access method according to the third embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, each embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, in this embodiment, the same components are given the same reference numerals and repeated descriptions are omitted.

(Implementation Method 1)

FIG7 is a diagram showing the main structure of the terminal 200 according to the present embodiment. The terminal 200 is capable of changing the configuration of the subframe configuration pattern (UL-DL Configuration) constituting one frame, which includes a downlink communication subframe (DL subframe) for downlink communication and an uplink communication subframe (UL subframe) for uplink communication. In the terminal 200, the decoding unit 210 stores the downlink data transmitted from the base station in a retransmission buffer (soft buffer) and decodes the downlink data, and the wireless transmission unit 222 transmits a response signal generated using the error detection result of the downlink data. Here, based on the maximum value of the number of retransmission processes (maximum number of DL HARQ processes) specified for each of the multiple configuration patterns that can be set by the terminal 200, the soft buffer is divided into multiple areas (IR buffers) for each retransmission process.

For simplicity, the following description describes a case where a single downlink component band is configured for terminal 200. Furthermore, the following description describes a case where MIMO (Multiple Input Multiple Output) is not configured for terminal 200 (non-MIMO). Specifically, in equation (1), K _C = 1 (using a single downlink component band) and K _MIMO = 1 (non-MIMO, number of multiplexing layers: 1). Specifically, the following description focuses on the maximum number of DL HARQ processes (M _{DL _ HARQ} ) shown in equation (1).

[Structure of base station]

FIG8 is a block diagram showing the configuration of base station 100 according to this embodiment. In FIG8 , base station 100 includes control section 101, control information generation section 102, coding section 103, modulation section 104, coding section 105, data transmission control section 106, modulation section 107, mapping section 108, IFFT (Inverse Fast Fourier Transform) section 109, CP adding section 110, radio transmission section 111, radio reception section 112, CP removal section 113, PUCCH extraction section 114, despreading section 115, sequence control section 116, correlation processing section 117, A/N determination section 118, bundled A/N despreading section 119, IDFT (Inverse Discrete Fourier Transform) section 120, bundled A/N determination section 121, and retransmission control signal generation section 122.

Control unit 101 assigns downlink resources for transmitting control information (i.e., downlink control information allocation resources) and downlink resources for transmitting downlink data (i.e., downlink data allocation resources) to a resource allocation target terminal 200 (hereinafter referred to as a "destination terminal" or simply "terminal"). This resource allocation is performed within the downlink component bands included in the component band group configured for resource allocation target terminal 200. Furthermore, downlink control information allocation resources are selected from resources corresponding to the downlink control channel (PDCCH) within each downlink component band. Furthermore, downlink data allocation resources are selected from resources corresponding to the downlink data channel (PDSCH) within each downlink component band. Furthermore, if there are multiple resource allocation target terminals 200, control unit 101 allocates different resources to each resource allocation target terminal 200.

The downlink control information allocation resource is equivalent to the above-mentioned L1/L2CCH. In other words, the downlink control information allocation resource is composed of one or more CCEs.

Furthermore, control unit 101 determines a coding rate to be used when transmitting control information to resource allocation target terminal 200. Since the amount of control information data varies depending on the coding rate, control unit 101 allocates downlink control information allocation resources having a number of CCEs capable of mapping the control information of that amount of data.

Furthermore, control section 101 outputs information regarding downlink data allocation resources to control information generating section 102. Furthermore, control section 101 outputs information regarding a coding rate to coding section 103. Furthermore, control section 101 determines a coding rate for transmission data (i.e., downlink data) and outputs it to coding section 105. Furthermore, control section 101 outputs information regarding downlink data allocation resources and downlink control information allocation resources to mapping section 108. Control section 101 controls the mapping of downlink data and downlink control information for the downlink data to the same downlink component band.

Control information generating section 102 generates control information including information regarding downlink data allocation resources and outputs it to encoding section 103. This control information is generated for each downlink component band. Furthermore, when there are multiple resource allocation target terminals 200, the control information includes the terminal ID of destination terminal 200 to distinguish between them. For example, the control information includes CRC bits masked with the terminal ID of destination terminal 200. This control information is sometimes referred to as "downlink assignment control information" or "Downlink Control Information (DCI)." Furthermore, control information generating section 102 includes retransmission information in the control information, for example, by referring to a retransmission control signal (not shown) generated by retransmission control signal generating section 122. This retransmission information indicates whether the downlink data transmission controlled by data transmission control section 106 is an initial transmission or a retransmission.

Coding section 103 encodes the control information according to the coding rate obtained from control section 101 , and outputs the encoded control information to modulation section 104 .

The modulation unit 104 modulates the encoded control information and outputs the obtained modulated signal to the mapping unit 108 .

Coding section 105 receives transmission data (ie, downlink data) for each destination terminal 200 and coding rate information from control section 101 , encodes the transmission data, and outputs the encoded data to data transmission control section 106 .

At the time of initial transmission, data transmission control section 106 holds the encoded transmission data and outputs the encoded transmission data to modulation section 107. The encoded transmission data is held for each destination terminal 200.

Furthermore, upon receiving a NACK or DTX for downlink data transmitted via a certain downlink component band from retransmission control signal generating section 122, data transmission control section 106 outputs the held data corresponding to the relevant downlink component band to modulation section 107. Upon receiving an ACK for downlink data transmitted via a certain downlink component band from retransmission control signal generating section 122, data transmission control section 106 deletes the held data corresponding to the relevant downlink component band.

Modulation section 107 modulates the encoded transmission data received from data transmission control section 106 , and outputs the modulated signal to mapping section 108 .

Mapping section 108 maps the modulated signal of the control information received from modulation section 104 to the resources indicated by the downlink control information allocation resources received from control section 101 , and outputs the result to IFFT section 109 .

Mapping section 108 also maps the modulated signal of the transmission data received from modulation section 107 to the resource (PDSCH (Downlink Data Channel)) indicated by the downlink data allocation resource (i.e., information included in the control information) received from control section 101 , and outputs the result to IFFT section 109 .

The control information and transmission data mapped to multiple subcarriers of multiple downlink unit frequency bands by the mapping unit 108 are converted from frequency domain signals to time domain signals in the IFFT unit 109. After the CP is added by the CP adding unit 110 to become an OFDM signal, the wireless transmission unit 111 performs D/A (Digital to Analog) conversion, amplification, up-conversion and other transmission processing, and then sends it to the terminal 200 via the antenna.

The wireless receiving unit 112 receives an uplink response signal or a reference signal transmitted from the terminal 200 via an antenna, and performs reception processing such as down-conversion and A/D conversion on the uplink response signal or the reference signal.

The CP removing unit 113 removes the CP added to the uplink response signal or the reference signal after receiving processing.

PUCCH extraction section 114 extracts the signal of the PUCCH region corresponding to the bundled ACK/NACK resource notified in advance to terminal 200 from the PUCCH signal included in the received signal. Specifically, PUCCH extraction section 114 extracts the data portion (i.e., the SC-FDMA symbol in which the bundled ACK/NACK signal is configured) and the reference signal portion (i.e., the SC-FDMA symbol in which the reference signal used to demodulate the bundled ACK/NACK signal is configured) of the PUCCH region corresponding to the bundled ACK/NACK resource. PUCCH extraction section 114 outputs the extracted data portion to bundled A/N despreading section 119 and outputs the reference signal portion to despreading section 115-1.

Furthermore, PUCCH extraction section 114 extracts multiple PUCCH regions from the PUCCH signal included in the received signal. These PUCCH regions correspond to the A/N resources associated with the CCEs occupied by the PDCCHs used to transmit downlink control information (DCI), as well as multiple A/N resources previously notified to terminal 200. A/N resources are resources where A/N signals should be transmitted. Specifically, PUCCH extraction section 114 extracts the data portion (SC-FDMA symbols allocated with uplink control signals) and the reference signal portion (SC-FDMA symbols allocated with reference signals used to demodulate uplink control signals) of the PUCCH regions corresponding to the A/N resources. PUCCH extraction section 114 then outputs both the extracted data portion and the reference signal portion to despreading section 115-2. In this way, a response signal is received using resources selected from the PUCCH resources associated with the CCEs and the specific PUCCH resources notified to terminal 200.

Sequence control section 116 generates a base sequence (i.e., a ZAC sequence with a sequence length of 12) for use in spreading the A/N signal, the reference signal for the A/N signal, and the reference signal for the bundled ACK/NACK signal, all of which are notified from terminal 200. Sequence control section 116 also determines correlation windows corresponding to resources (hereinafter referred to as "reference signal resources") in which reference signals may be allocated, among the PUCCH resources potentially used by terminal 200. Sequence control section 116 outputs information indicating the correlation windows corresponding to the reference signal resources in which reference signals may be allocated, among the bundled ACK/NACK resources, and the base sequence to correlation processing section 117-1. Sequence control section 116 outputs information indicating the correlation windows corresponding to the reference signal resources, and the base sequence to correlation processing section 117-1. Sequence control section 116 also outputs information indicating the correlation windows corresponding to the A/N resources in which the A/N signal and the reference signal for the A/N signal are allocated, and the base sequence to correlation processing section 117-2.

The despreading unit 115 - 1 and the correlation processing unit 117 - 1 process the reference signal extracted from the PUCCH region corresponding to the bundled ACK/NACK resource.

Specifically, despreading section 115-1 despreads the reference signal portion using the Walsh sequence that terminal 200 should use for secondary spreading of the reference signal bundled with the ACK/NACK resource, and outputs the despread signal to correlation processing section 117-1.

Correlation processing section 117-1 uses information indicating the correlation window corresponding to the reference signal resource and the base sequence to calculate a correlation value between the signal input from despreading section 115-1 and a base sequence that may be used for primary spreading in terminal 200. Correlation processing section 117-1 then outputs the correlation value to bundled A/N determination section 121.

The despreading unit 115 - 2 and the correlation processing unit 117 - 2 process the reference signals and A/N extracted from a plurality of PUCCH regions corresponding to a plurality of A/N resources.

Specifically, the despreading unit 115-2 uses the Walsh sequence and DFT sequence that the terminal 200 should use in the secondary spread of the data part and the reference signal part of each A/N resource to despread the data part and the reference signal part, and outputs the despread signal to the correlation processing unit 117-2.

Correlation processing section 117-2 uses information indicating the correlation window corresponding to each A/N resource and the base sequence to calculate correlation values between the signal input from despreading section 115-2 and the base sequence that may be used for primary spreading in terminal 200. Correlation processing section 117-2 then outputs each correlation value to A/N determination section 118.

Based on the multiple correlation values input from correlation processing section 117-2, A/N determination section 118 determines which A/N resource terminal 200 used to transmit a signal, or whether no A/N resource was used. Furthermore, if A/N determination section 118 determines that terminal 200 used a particular A/N resource to transmit a signal, it performs coherent detection using a component corresponding to the reference signal and a component corresponding to the A/N signal, and outputs the coherent detection result to retransmission control signal generation section 122. On the other hand, if A/N determination section 118 determines that terminal 200 did not use any A/N resource, it outputs a message indicating that no A/N resource was used to retransmission control signal generation section 122.

Bundled A/N despreading section 119 despreads the bundled ACK/NACK signal corresponding to the data portion of the bundled ACK/NACK resource input from PUCCH extraction section 114 using a DFT sequence, and outputs the signal to IDFT section 120 .

IDFT section 120 transforms the frequency-domain bundled ACK/NACK signal input from bundled A/N despreading section 119 into a time-domain signal through IDFT processing, and outputs the time-domain bundled ACK/NACK signal to bundled A/N determination section 121 .

Bundled A/N decision section 121 demodulates the bundled ACK/NACK signal corresponding to the data portion of the bundled ACK/NACK resource input from IDFT section 120, using the reference signal information of the bundled ACK/NACK signal input from correlation processing section 117-1. Bundled A/N decision section 121 also decodes the demodulated bundled ACK/NACK signal and outputs the decoding result as bundled A/N information to retransmission control signal generation section 122. However, if the correlation value input from correlation processing section 117-1 is smaller than the threshold, indicating that terminal 200 is not transmitting a signal using the bundled A/N resource, bundled A/N decision section 121 outputs this to retransmission control signal generation section 122.

Retransmission control signal generating section 122 determines whether data (downlink data) transmitted via a downlink component band should be retransmitted based on information input from bundled A/N determining section 121, information input from A/N determining section 118, and information indicating a group number pre-set for base station 200. Retransmission control signal generating section 122 generates a retransmission control signal based on the determination result. Specifically, if retransmission of downlink data transmitted via a downlink component band is determined to be necessary, retransmission control signal generating section 122 generates a retransmission control signal indicating a retransmission command for the downlink data and outputs the retransmission control signal to data transmission control section 106. If retransmission of downlink data transmitted via a downlink component band is determined to be unnecessary, retransmission control signal generating section 122 generates a retransmission control signal indicating that the downlink data transmitted via the downlink component band should not be retransmitted and outputs the retransmission control signal to data transmission control section 106.

[Structure of the terminal]

FIG9 is a block diagram showing the configuration of terminal 200 according to this embodiment. In FIG9 , terminal 200 includes a wireless receiving unit 201, a CP removing unit 202, an FFT (Fast Fourier Transform) unit 203, an extracting unit 204, a demodulating unit 205, a decoding unit 206, a determining unit 207, a controlling unit 208, a demodulating unit 209, a decoding unit 210, a CRC unit 211, a response signal generating unit 212, a coding and modulating unit 213, primary spreading units 214-1 and 214-2, secondary spreading units 215-1 and 215-2, a DFT unit 216, a spreading unit 217, IFFT units 218-1, 218-2, and 218-3, CP adding units 219-1, 219-2, and 219-3, a time division multiplexing unit 220, a selecting unit 221, and a wireless transmitting unit 222.

Wireless receiving section 201 receives OFDM signals transmitted from base station 100 via an antenna and performs reception processing such as down-conversion and A/D conversion on the received OFDM signals. The received OFDM signals include PDSCH signals (downlink data) allocated to resources within the PDSCH or PDCCH signals allocated to resources within the PDCCH.

The CP removing unit 202 removes the CP added to the OFDM signal after receiving processing.

The FFT unit 203 performs FFT on the received OFDM signal to transform it into a frequency domain signal, and outputs the obtained received signal to the extraction unit 204 .

Extraction section 204 extracts the downlink control channel signal (PDCCH signal) from the received signal obtained from FFT section 203 based on the input coding rate information. Specifically, the number of CCEs (component element cards) constituting the downlink control information allocation resource varies depending on the coding rate. Therefore, extraction section 204 extracts the downlink control channel signal using the number of CCEs corresponding to the coding rate as extraction units. Furthermore, the downlink control channel signal is extracted for each downlink component band. The extracted downlink control channel signal is output to demodulation section 205.

Furthermore, extraction section 204 extracts downlink data (downlink data channel signal (PDSCH signal)) from the received signal based on information regarding downlink data allocation resources addressed to the own apparatus obtained from determination section 207 (described later), and outputs the information to demodulation section 209. In this manner, extraction section 204 receives downlink control information (DCI) mapped to the PDCCH and receives downlink data via the PDSCH.

The demodulation unit 205 demodulates the downlink control channel signal obtained from the extraction unit 204 and outputs the obtained demodulation result to the decoding unit 206 .

Decoding section 206 decodes the demodulation result obtained from demodulation section 205 based on the input coding rate information, and outputs the obtained decoding result to determination section 207.

Determination section 207 blindly determines (monitors) whether the control information included in the decoding result obtained from decoding section 206 is control information addressed to the own device. This determination is performed per decoding result corresponding to the aforementioned extraction unit. For example, determination section 207 demasks the CRC bits using the own device's terminal ID and determines that control information with a CRC = OK (error-free) is control information addressed to the own device. Determination section 207 then outputs information regarding downlink data resource allocation for the own device, included in the control information addressed to the own device, to extraction section 204.

Furthermore, determination section 207 outputs retransmission information included in the control information addressed to its own apparatus to decoding section 210. The retransmission information indicates whether the downlink data transmission to its own apparatus is the initial transmission or the retransmission.

Furthermore, upon detecting control information addressed to the own device (i.e., downlink allocation control information), determination section 207 notifies control section 208 of the generation (presence) of an ACK/NACK signal. Furthermore, upon detecting control information addressed to the own device from a PDCCH signal, determination section 207 outputs information regarding the CCEs occupied by the PDCCH to control section 208.

Control section 208 determines the A/N resource associated with the CCE based on the CCE-related information input from determination section 207. Control section 208 then outputs the base sequence and cyclic shift corresponding to the A/N resource associated with the CCE, or the A/N resource previously notified from base station 100, to primary spreading section 214-1, and outputs the Walsh sequence and DFT sequence corresponding to the A/N resource to secondary spreading section 215-1. Control section 208 also outputs frequency resource information for the A/N resource to IFFT section 218-1.

If it is determined that a bundled ACK/NACK signal should be transmitted using a bundled ACK/NACK resource, control section 208 outputs the base sequence and cyclic shift value corresponding to the reference signal portion (reference signal resource) of the bundled ACK/NACK resource, previously notified from base station 100, to primary spreading section 214-2 and the Walsh sequence to secondary spreading section 215-2. Furthermore, control section 208 outputs frequency resource information for the bundled ACK/NACK resource to IFFT section 218-2.

Furthermore, control section 208 outputs the DFT sequence used for spreading the data portion of the bundled ACK/NACK resource to spreading section 217, and outputs the frequency resource information of the bundled ACK/NACK resource to IFFT section 218-3.

Furthermore, control section 208 instructs selection section 221 to select either a bundled ACK/NACK resource or an A/N resource and output the selected resource to wireless transmission section 222. Furthermore, control section 208 instructs response signal generation section 212 to generate either a bundled ACK/NACK signal or an ACK/NACK signal based on the selected resource.

Demodulation section 209 demodulates the downlink data received from extraction section 204 , and outputs the demodulated downlink data (LLR) to decoding section 210 .

When the retransmission information received from decision section 207 indicates initial transmission, decoding section 210 stores the downlink data (LLRs) received from demodulation section 209 in a retransmission buffer (soft buffer). Furthermore, decoding section 210 decodes the downlink data received from demodulation section 209 and outputs the decoded downlink data to CRC section 211. On the other hand, when the retransmission information received from decision section 207 indicates retransmission, decoding section 210 combines the downlink data received from demodulation section 209 with the downlink data read from the retransmission buffer and stores the combined downlink data again in the retransmission buffer. Furthermore, decoding section 210 decodes the combined downlink data and outputs the decoded downlink data to CRC section 211. Details of the calculation method (division method) for the retransmission buffer size and the method for storing downlink data in the retransmission buffer will be discussed later.

CRC section 211 generates the decoded downlink data received from decoding section 210, performs error detection using CRC, and outputs ACK to response signal generating section 212 if CRC = OK (no error), or NACK to response signal generating section 212 if CRC = NG (error). Furthermore, CRC section 211 outputs the decoded downlink data as received data if CRC = OK (no error).

Response signal generating section 212 generates a response signal based on the reception status of the downlink data in each downlink component band (the error detection results of the downlink data), input from CRC section 211, and information indicating a preset group number. Specifically, when instructed by control section 208 to generate a bundled ACK/NACK signal, response signal generating section 212 generates a bundled ACK/NACK signal containing the error detection results for each downlink component band as dedicated data. On the other hand, when instructed by control section 208 to generate an ACK/NACK signal, response signal generating section 212 generates a single-symbol ACK/NACK signal. Response signal generating section 212 then outputs the generated response signal to coding and modulation section 213.

When a bundled ACK/NACK signal is input, coding and modulation section 213 encodes and modulates the input bundled ACK/NACK signal to generate a 12-symbol modulated signal, and outputs it to DFT section 216. Alternatively, when a 1-symbol ACK/NACK signal is input, coding and modulation section 213 modulates the ACK/NACK signal and outputs it to primary spreading section 214-1.

The primary spreading units 214-1 and 214-2 corresponding to the A/N resources and the reference signal resources bundled with the ACK/NACK resources spread the ACK/NACK signals or reference signals using the base sequences corresponding to the resources according to the instructions of the control unit 208, and output the spread signals to the secondary spreading units 215-1 and 215-2.

The secondary spreading units 215-1 and 215-2 spread the input primary spread signal using a Walsh sequence or a DFT sequence according to the instruction of the control unit 208, and output it to the IFFT units 218-1 and 218-2.

The DFT unit 216 aggregates the 12 input time-series bundled ACK/NACK signals and performs DFT processing to obtain 12 signal components on the frequency axis. The DFT unit 216 then outputs the 12 signal components to the spreading unit 217.

Spreading section 217 spreads the 12 signal components input from DFT section 216 using the DFT sequence instructed by control section 208, and outputs the result to IFFT section 218-3.

IFFT units 218-1, 218-2, and 218-3 perform IFFT processing by associating the input signals with the frequency positions to be allocated, according to the instructions of control unit 208. As a result, the signals input to IFFT units 218-1, 218-2, and 218-3 (i.e., ACK/NACK signals, reference signals for A/N resources, reference signals for bundled ACK/NACK resources, and bundled ACK/NACK signals) are transformed into time-domain signals.

The CP adding sections 219 - 1 , 219 - 2 , and 219 - 3 add the same signal as the tail portion of the signal after IFFT as a CP to the head of the signal.

The time division multiplexing unit 220 time division multiplexes the bundled ACK/NACK signal (i.e., the signal sent using the data part of the bundled ACK/NACK resource) input from the CP attachment unit 219-3 and the reference signal of the bundled ACK/NACK resource input from the CP attachment unit 219-2 into the bundled ACK/NACK resource, and outputs the resulting signal to the selection unit 221.

Selector 221 selects either the bundled ACK/NACK resource input from time division multiplexing section 220 or the A/N resource input from CP adding section 219 - 1 according to an instruction from control section 208 , and outputs the signal allocated to the selected resource to radio transmitter 222 .

Wireless transmission section 222 performs transmission processing such as D/A conversion, amplification, and up-conversion on the signal received from selection section 221 , and transmits the signal to base station 100 through an antenna.

[Operations of Base Station 100 and Terminal 200]

The operations of base station 100 and terminal 200 having the above configurations will be described.

The base station 100 notifies the terminal 200 in advance of a set of configurable UL-DL configurations. The set of configurable UL-DL configurations is information indicating UL-DL configurations that can be changed in TDD eIMTA.

Terminal 200 divides the soft buffer into multiple IR buffers based on the largest maximum number of DL HARQ processes among the maximum numbers of DL HARQ processes specified by each UL-DL Configuration in the set of configurable UL-DL Configurations, and calculates the IR buffer size accordingly.

10 and 11 and equation (2) are used to describe a method for calculating the IR buffer size (N _IR ) in terminal 200. In the following description, in equation (2), K _C = 1 (using one downlink component band) and K _MIMO = 1 (non-MIMO).

In Figures 10 and 11, in terminal 200, the set of UL-DL Configurations (eIMTA_Config) that can be changed through TDD eIMTA is UL-DL Configuration #0 (hereinafter sometimes represented as "Config #0". The same applies to other UL-DL Configurations.), Config #1, and Config #6 (i.e., eIMTA_Config = {#0, #1, #6}).

FIG10 shows the maximum number of DL HARQ processes (M _{DL_HARQ} ) specified for each UL-DL Configuration. As shown in FIG10 , the maximum number of DL HARQ processes specified for Config#0, Config#1, and Config#6, which are eIMTA_Configs of terminal 200, are 4, 7, and 6, respectively. That is, M _{DL_HARQ,eIMTA_Config} = {4, 6, 7} as shown in equation (2).

Therefore, the largest maximum number of DL HARQ processes (maximum value) among the maximum number of DL HARQ processes specified by each UL-DL Configuration in the set of changeable UL-DL Configurations is 7. That is, max(M _{DL — HARQ, eIMTA_Config} )=7 as shown in equation (2).

The soft buffer (buffer capacity: N _soft ) is divided equally (here, into 7 equal parts) into IR buffers corresponding to the smaller value (min(max(M _{DL _ HARQ , eIMTA_Config} )=7) of the maximum number of DL HARQ processes (max(M _{DL _ HARQ} , _{eIMTA_Config} )=7) and the maximum allowed number of DL HARQ processes that _terminal 200 can handle (M _limit =8).

FIG11 shows an example of a method for allocating soft buffers when the UL-DL Configuration in the terminal 200 in which eIMTA_Config={#0, #1, #6} is set is changed from Config#0 to Config#1.

The maximum number of DL HARQ processes differs between different UL-DL Configurations before and after the change. However, as described above, the soft buffer of the terminal 200 is divided into 7 equal parts (N _IR =N _soft /7), regardless of the UL-DL Configuration before and after the change.

Furthermore, among the 7 IR buffers, each DL HARQ process in the UL-DL Configuration is allocated to the IR buffer (IR buffer group) of the maximum number of DL HARQ processes specified by the UL-DL Configuration currently set for the terminal 200. Specifically, as shown in FIG11 , before the change (Config#0), among the 7 IR buffers obtained by dividing the soft buffer into 7 equal parts, the 1st to 4th IR buffers from the left (the number of which is the maximum number of DL HARQ processes specified by Config#0) are allocated to DL HARQ processes with DL HARQ process numbers of 1 to 4, respectively. Similarly, after the change (Config#0), among the 7 IR buffers (the number of which is the maximum number of DL HARQ processes specified by Config#1), DL HARQ processes with DL HARQ process numbers of 1 to 7 are allocated to each.

That is, as shown in FIG11 , before the change (Config#0), terminal 200 uses four of the seven IR buffers, corresponding to the maximum number of DL HARQ processes specified in Config#0, to perform DL HARQ. On the other hand, as shown in FIG11 , after the change (Config#1), terminal 200 uses all seven IR buffers (corresponding to the maximum number of DL HARQ processes specified in Config#1) to perform DL HARQ.

As a result, while the maximum number of DL HARQ processes differs before the change (Config#0) and after the change (Config#1), the IR buffer locations (downlink data configuration locations) for DL HARQ processes numbered 1 to 4 remain the same. Therefore, terminal 200 can correctly read downlink data (LLRs) for the same DL HARQ process (DL HARQ process number 2 in FIG. 11 ) stored in the IR buffer at the same location on the soft buffer before and after the UL-DL Configuration change. This means that terminal 200 can continue DL HARQ processes before and after the UL-DL Configuration change.

In addition, as shown in FIG11 , when the maximum number of DL HARQ processes specified in the UL-DL Configuration currently used by the terminal 200 (for example, 4 for Config#0) is smaller than the maximum number of DL HARQ processes specified in each UL-DL Configuration of the set of UL-DL Configurations that can be set for the terminal 200 (for example, 7 in FIG10 and FIG11 ), the IR buffer for the difference in the number of DL HARQ processes (the IR buffer area indicated by N/A (Not Available) shown in FIG11 ) is not used. That is, the remaining IR buffers other than the IR buffers allocated to each DL HARQ process of the UL-DL Configuration currently set for the terminal 200 among the multiple IR buffers obtained by dividing the soft buffer are not used. Hereinafter, the above-mentioned unused IR buffer area is sometimes referred to as the "remaining IR buffer area."

As described above, in this embodiment, terminal 200 divides the soft buffer into multiple IR buffers for each DL HARQ process based on the maximum value of the maximum number of DL HARQ processes specified for each UL-DL Configuration that terminal 200 can configure. This allows terminal 200 to correctly read data stored in the IR buffer corresponding to the same DL HARQ process before and after a UL-DL Configuration change, even if at least one of the maximum number of DL HARQ processes specified for each UL-DL Configuration that terminal 200 can configure is less than 8 (M _limit ) (in FIG10 , when the UL-DL Configuration can be changed to at least one of Config#0, Config#1, or Config#6). In other words, terminal 200 can continue DL HARQ processes before and after a UL-DL Configuration change. Thus, according to this embodiment, by continuing DL HARQ processes for downlink data before and after a UL-DL Configuration change, degradation in HARQ retransmission performance can be suppressed.

(Implementation Method 2)

While the case where the remaining IR buffer area is not used was described in Embodiment 1, this embodiment describes a method for effectively using the remaining IR buffer area.

Next, the following describes method 1 ( FIG. 12A ) and method 2 ( FIG. 12B ) of utilizing the remaining IR buffer area.

In the following description, similar to Embodiment 1, the set of UL-DL Configurations that can be changed by TDD eIMTA for terminal 200 is Config#0, Config#1, and Config#6 (i.e., eIMTA_Config = {#0, #1, #6}). That is, as shown in FIG12A and FIG12B , terminal 200 divides the soft buffer into seven.

That is, in method 1 ( FIG12A ), remaining IR buffer areas (three IR buffers) are generated before the UL-DL Configuration is changed (Config#0: Maximum number of DL HARQ processes: 4). On the other hand, in method 2 ( FIG12B ), remaining IR buffer areas (three IR buffers) are generated after the UL-DL Configuration is changed (Config#0).

<Usage Method 1>

In FIG12A , the terminal 200 uses the remaining IR buffer area as an additional IR buffer area for the DL HARQ process in the UL-DL Configuration being used. Specifically, in FIG12A , the terminal 200 uses the three remaining IR buffer areas as additional IR buffer areas for three DL HARQ processes (DL HARQ process numbers 1 to 3) out of the four DL HARQ processes (DL HARQ process numbers 1 to 4) in Configuration #0 being used by the terminal 200.

That is, in the remaining IR buffer area, a number of DL HARQ processes (3 processes in Figure 12A) equivalent to the difference between the total number of IR buffers obtained by dividing the soft buffer (7 processes in Figure 12A) and the maximum number of DL HARQ processes specified in the UL-DL Configuration being used (4 processes in Figure 12A) are allocated.

Therefore, for the DL HARQ processes with DL HARQ process numbers 1 to 3, the terminal 200 can use two IR buffers.

Furthermore, when a change in UL-DL Configuration is instructed from the base station 100 , the terminal 200 resets the downlink data stored in the remaining IR buffer area (additional IR buffer area).

As described above, when the maximum number of DL HARQ processes specified for the UL-DL Configuration currently set for the terminal 200 is less than the number of IR buffers (the number of soft buffer divisions), any DL HARQ process in the UL-DL Configuration is allocated in the remaining IR buffers (equivalent to the second area group, that is, the remaining IR buffer area) among multiple IR buffers other than the IR buffer (equivalent to the first area group) to which the DL HARQ process in the UL-DLConfiguration is allocated.

In this way, the terminal 200 can increase the IR buffer size of each DL HARQ process by using the remaining IR buffer area as an additional IR buffer area for the DL HARQ process existing in the UL-DL Configuration being used. As a result, compared with the case where the remaining IR buffer area is not used (for example, refer to Figure 11), the error correction capability can be improved and the HARQ retransmission performance can be improved.

Furthermore, similar to Embodiment 1, terminal 200 can correctly read the data stored in the IR buffer (IR buffers other than the remaining IR buffer area) corresponding to the same DL HARQ process (DL HARQ process numbers 1 to 4 in FIG12A ) before and after the UL-DL Configuration change. Therefore, even if the downlink data stored in the remaining IR buffer area (the additional IR buffer area) is reset due to the change in the UL-DL Configuration, terminal 200 can continue the DL HARQ process.

12A illustrates the case where multiple DL HARQ processes in the current UL-DL Configuration are allocated to multiple additional IR buffer areas. However, only a single DL HARQ process in the current UL-DL Configuration may be allocated to multiple additional IR buffer areas.

In addition, FIG12A illustrates a case where the entire additional IR buffer area is divided into three equal parts (divided into the same size as the IR buffer) and allocated to three DL HARQ processes respectively, but the present invention is not limited thereto. For example, the entire additional IR buffer area may be equally redivided (divided into four equal parts in the case of Config#0 shown in FIG12A ) according to the maximum number of DL HARQ processes specified in the UL-DL Configuration being used, and all DL HARQ processes in the UL-DL Configuration are allocated to each of the redivided areas.

Furthermore, as described above, due to the increase in the number of DL HARQ processes associated with a change in the UL-DL Configuration, the remaining IR buffer area may be reset. To address this, when the remaining IR buffer area is used as an additional IR buffer area, terminal 200 can prioritize storing parity bits in the additional IR buffer area. This prevents the resetting of highly important system parity bits.

<Usage Method 2>

In FIG12B , the terminal 200 uses the remaining IR buffer areas as IR buffer areas for DL HARQ processes that do not exist in the UL-DL Configuration currently being used. Specifically, in FIG12B , the terminal 200 uses the three remaining IR buffer areas as IR buffer areas for DL HARQ processes (DL HARQ process numbers 1 to 4) that do not exist in the DL HARQ processes of Configuration #0 currently being used by the terminal 200 and that exist in Configuration #1 that the terminal 200 used immediately before the change (DL HARQ process numbers 5 to 7).

That is to say, when the maximum number of DL HARQ processes specified in the UL-DL Configuration currently set for the terminal 200 is less than the number of IR buffers (the number of soft buffer divisions), in the remaining IR buffers (equivalent to the second area group, that is, the remaining IR buffer area) other than the IR buffer (equivalent to the first area group) to which the DL HARQ process in the UL-DLConfiguration is allocated among the multiple IR buffers, the DLHARQ processes allocated in the area equivalent to the remaining IR buffer area in the UL-DLConfiguration set for the terminal 200 last time continue to be allocated.

Therefore, even when the terminal 200 is instructed by the base station 100 to change the UL-DL Configuration from Config#1 to Config#0, the terminal 200 does not reset the downlink link data stored in the IR buffer area (DL HARQ process numbers 5 to 7) that becomes the remaining IR buffer area, but continues the DL HARQ process for the remaining IR buffer area.

As described above, the terminal 200 uses the remaining IR buffer area as an IR buffer area for the DL HARQ process that does not exist in the UL-DL Configuration being used. As a result, even if the number of DL HARQ processes decreases with the change of UL-DL Configuration, DL HARQ can be continued in the reduced DL HARQ processes. That is, in the above-mentioned reduced DL HARQ processes, when they are in an unfinished state when the UL-DL Configuration is changed, the terminal 200 can continue DL HARQ. As a result, compared with the case where the remaining IR buffer area is not used (for example, refer to Figure 11), the HARQ retransmission performance can be improved.

12B illustrates the case where multiple DL HARQ processes in the last configured UL-DL Configuration are allocated to multiple remaining IR buffer areas. However, only a single DL HARQ process in the last configured UL-DL Configuration may be allocated to multiple remaining IR buffer areas.

The above describes the method 1 and the method 2 for utilizing the remaining IR buffer area.

Thus, in this embodiment, even if the maximum number of DL HARQ processes specified in the UL-DL Configuration used by terminal 200 is smaller than the number of multiple IR buffers obtained by dividing the soft buffer (the number of soft buffer divisions), the IR buffers corresponding to the difference in the number of DL HARQ processes (the remaining IR buffer area) can be effectively utilized. Thus, this embodiment can further improve HARQ retransmission performance compared to Embodiment 1.

In addition, as to whether to use the remaining IR buffer area as an additional IR buffer area for the DL HARQ process existing in the UL-DL Configuration being used (using method 1: FIG. 12A ), or to use the remaining IR buffer area as an IR buffer area for the DL HARQ process not existing in the UL-DL Configuration being used (using method 2: FIG. 12B ), either one may be predetermined, or may be switched according to the setting. For example, when the terminal 200 needs to continue the DL HARQ process before the change after the UL-DL Configuration is changed, the method 2 ( FIG. 12B ) may be set to be used, and when the DL HARQ process before the change does not need to be continued after the UL-DL Configuration is changed, the method 1 ( FIG. 12A ) may be set to be used.

(Implementation 3)

In this embodiment, a case will be described in which, while utilizing the remaining IR buffer area in the same manner as in the second embodiment, it is further specified to which DL HARQ process the remaining IR buffer area is allocated.

In Embodiment 2 (FIGS. 12A and 12B), it is not specified to which DL HARQ process the remaining IR buffer area is allocated and the size thereof. Therefore, due to the change of the UL-DL Configuration, during the repeated resetting of each IR buffer or the continuation of the DL HARQ process (sometimes simply referred to as "HARQ continuation"), even if the same UL-DL Configuration is changed again, the order of the DL HARQ process numbers to which the remaining IR buffer area is allocated is different from the order of the DL HARQ process numbers initially allocated.

For example, FIG13 shows allocation of DL HARQ processes in the remaining IR buffer area when the UL-DL Configuration is changed in the order of Config#0, Config#1, Config#6, and Config#0.

As shown in Figure 13, when Config#0 is initially configured, DL HARQ processes are allocated to the three remaining IR buffer areas in the order of DL HARQ process numbers 1, 2, and 3. Next, by changing the configuration to Config#1, all remaining IR buffer areas are reset, and by changing the configuration to Config#6, a DL HARQ process with DL HARQ process number 1 is allocated to one remaining IR buffer area. Furthermore, when the configuration is changed to Config#1 again, the DL HARQ process with DL HARQ process number 1 continues to be allocated to the remaining IR buffer areas that existed before the configuration change, and DL HARQ processes are allocated to the two newly generated remaining IR buffer areas in the order of DL HARQ process numbers 2 and 3.

That is, in Figure 13, the order of the DL HARQ processes allocated in the remaining IR buffer area when Config#0 is reconfigured (the order of DL HARQ process numbers 2, 3, and 1) is different from the order of the DL HARQ processes allocated in the remaining IR buffer area when Config#0 was initially configured (the order of DL HARQ process numbers 1, 2, and 3). Thus, the order of the DL HARQ processes stored in the remaining IR buffer area changes as the UL-DL Configuration changes.

As a result, in the example of FIG13 , the IR buffer corresponding to DL HARQ process number 1 (including the remaining IR buffer area) is divided into three cases: the first from the left (Case 1: when Config#1 is set), the first and fifth from the left (Case 2: when Config#0 is initially set), and the first and seventh from the left (Case 3: when Config#6 is set and when Config#0 is set again). This means that the terminal's soft buffer access processing becomes complicated.

In contrast, in this embodiment, a method of simplifying the access process to the soft buffer in terminal 200 will be described.

14 and 15 show the soft buffer structure of this embodiment.

In the following description, similar to Embodiment 2, the set of UL-DL Configurations changeable by TDD eIMTA for terminal 200 is Config#0, Config#1, and Config#6 (i.e., eIMTA_Config={#0, #1, #6}). That is, the soft buffer in terminal 200 is divided into seven.

Figure 14 shows the case of changing the UL-DL Configuration in the order of Config#0, Config#6, and Config#1, and Figure 15 shows the case of changing the UL-DL Configuration in the order of Config#1, Config#6, and Config#0. In Figures 14 and 15, when Config#0 is set, a maximum of three remaining IR buffer areas are generated (the 5th to 7th IR buffer areas from the left), and when Config#6 is set, a single remaining IR buffer area is generated (the 7th IR buffer area from the left).

In this embodiment, the multiple IR buffers obtained by dividing the soft buffer are pre-correlated with each DL HARQ process in each UL-DL Configuration.

Specifically, in FIG. 14 and FIG. 15 , the first IR buffer to the fourth IR buffer from the left among the seven IR buffers correspond to DL HARQ processes with DL HARQ process numbers 1 to 4, respectively.

14 and 15 , the fifth IR buffer from the left among the seven IR buffers corresponds to a DL HARQ process with a DL HARQ process number of 1 and a DL HARQ process with a DL HARQ process number of 1. Similarly, the sixth IR buffer from the left corresponds to a DL HARQ process with a DL HARQ process number of 6 and a DL HARQ process with a DL HARQ process number of 2. Furthermore, the seventh IR buffer from the left corresponds to a DL HARQ process with a DL HARQ process number of 7 and a DL HARQ process with a DL HARQ process number of 3.

That is, the IR buffer area corresponding to the DL HARQ process number 5 and the remaining IR buffer area corresponding to the DL HARQ process number 1 are a common IR buffer. Similarly, the IR buffer area corresponding to the DL HARQ process number 6 and the remaining IR buffer area corresponding to the DL HARQ process #2 are a common IR buffer. In addition, the IR buffer area corresponding to the DL HARQ process number 7 and the remaining IR buffer area corresponding to the DL HARQ process #3 are a common IR buffer. That is, in Figures 14 and 15, a common IR buffer area is allocated to the DL HARQ process number n (n=1, 2, 3) and the DL HARQ process number n+4. In other words, each remaining IR buffer area is fixedly corresponding to the DL HARQ process number regardless of the change of the UL-DL Configuration.

To illustrate the effect of the simplification of the memory structure of this embodiment, FIG16 shows the allocation of DL HARQ processes in the remaining IR buffer area when the UL-DL Configuration transition is the same as that in FIG13 .

In Figure 16, regardless of the UL-DL Configuration, the DL HARQ processes are always allocated in the order of DL HARQ process numbers 1, 2, and 3 in the three remaining IR buffer areas. Therefore, in the example of Figure 16, the IR buffer corresponding to DL HARQ process number 1 (including the remaining IR buffer area) is divided into the following two cases: only the case where it is the first from the left (case 1: when Config#1 is set), and the case where it is the first and fifth from the left (case 2: when Config#0 is set). That is, the number of positions that the IR buffer corresponding to DL HARQ process number 1 can take is 3 in Figure 13, but can be reduced to 2 in this embodiment. That is, in Figure 16, compared with Figure 13, the access process to the soft buffer in the terminal 200 can be simplified.

FIG17 is a conceptual diagram showing the correspondence between the IR buffer and the DL HARQ process number.

In FIG17 , the IR buffer obtained by equally dividing the soft buffer (buffer capacity N _soft ) into 8 (= min(max(M _{DL _HARQ} , _{eIMTA_Config} ), M _limit )) is one unit (thus, there are a total of min(max(M _{DL _HARQ , eIMTA_Config} ), M _limit ) = 8 units). Furthermore, among the multiple UL-DL configurations that can be configured for terminal 200, the DL HARQ processes whose number is equal to the maximum number of DL HARQ processes specified for each UL-DL configuration are assigned DL HARQ process numbers in ascending order starting from the same number (here, "1"). Furthermore, in FIG17 , the minimum value (min(M _{DL _HARQ , eIMTA_Config} )) of the maximum number of DL HARQ processes specified for each of the multiple UL-DL configurations that can be configured for terminal 200 is 6 processes. That is, the difference between the number of IR buffers obtained by dividing the soft buffer and the minimum value (=min(max(M _{DL_HARQ, eIMTA_Config} ), M _limit )-min(min(M _{DL_HARQ, eIMTA_Config} ), M _limit )) is 2.

In FIG17 , 6 (=min(min(M _{DL_HARQ, eIMTA_Config} ), M _limit )) units of the 8-unit IR buffer are allocated one by one to 6 (=min(min(M _{DL_HARQ, eIMTA_Config} ), M _limit )) DL HARQ processes (DL HARQ process numbers are 1 to 6) (correspondence indicated by the solid arrows). That is, in the IR buffer corresponding to the minimum value (6 processes) of the maximum number of DL HARQ processes among the multiple IR buffers (corresponding to the third region group), the DL HARQ processes corresponding to the minimum value (6 processes) are fixedly associated in ascending order, starting from DL HARQ process number 1, with the DL HARQ process number up to 6.

On the other hand, the remaining 2 (=min(max(M _{DL_HARQ} , _{eIMTA_Config} ), M _limit )-min(min(M _{DL_HARQ , eIMTA_Config} ), M _limit )) units of the 8-unit IR buffer are allocated to the remaining 2 (=min(max(M _{DL_HARQ , eIMTA_Config} ), M _limit )-min(min(M _{DL_HARQ , eIMTA_Config} ), M _limit )) DL HARQ processes (DL HARQ process numbers are 7 and 8), and are also allocated to 2 (=min(max(M DL_HARQ , eIMTA_Config ), M limit )-min(min(M _{DL_HARQ , eIMTA_Config} ), M _limit )) DL HARQ processes of the 6 (=min(min(M _{DL_HARQ , eIMTA_Config )} , M _limit )) DL HARQ processes _to which one unit _of IR buffer has been allocated, each. HARQ process (correspondence shown by the dotted arrow). That is, in the remaining IR buffers (equivalent to the fourth regional group) other than the IR buffers (equivalent to the third regional group) to which the DL HARQ processes corresponding to the minimum value (6 processes) are allocated among the multiple IR buffers, starting from DL HARQ process number 7, which is the next number after DL HARQ process number 6, the DL HARQ processes corresponding to the number of the difference (2 processes) are fixed in ascending order, and the DL HARQ processes corresponding to the number of the difference (2 processes) among the DL HARQ processes with DL HARQ process numbers 1 to 6 are fixed (here, DL HARQ process numbers 1 and 2).

As described above, according to this embodiment, the access location (buffer address) to the soft buffer of the DL HARQ process number is fixed regardless of changes in the UL-DL Configuration. This simplifies the soft buffer access process in terminal 200.

14 and 15 illustrate the case where DL HARQ process number n (n=1, 2, 3) and DL HARQ process number n+4 are allocated to a common IR buffer area. However, the combination of DL HARQ process numbers allocated to a common IR buffer area is not limited to this.

In addition, in Figure 16, the 1st IR buffer and the 5th IR buffer from the left are configured at discrete positions on the soft buffer, but this is an example of the logical configuration (logical address) of the IR buffer, and the physical configuration (physical address) of these IR buffers can be configured at adjacent positions on the soft buffer.

Furthermore, in the IR buffers corresponding to DL HARQ processes #1 to #4 shown in Figures 14 and 15, parity bits can be preferentially stored in the IR buffer unit shared with any of DL HARQ processes #5 to #7 (i.e., the remaining IR buffer area). This prevents the highly important system parity bits from being reset with changes to the UL-DL Configuration.

The embodiments of the present invention have been described above.

In addition, in the above embodiment, instead of notifying the terminal 200 of the set of UL-DL Configurations that can be changed by the terminal 200, the base station 100 may calculate min(max(M _{DL _HARQ , eIMTA_Config} , M _limit )) shown in equation (2) and notify the terminal 200 of the calculation result. In this case, the calculation result of min(max(M _{DL _HARQ , eIMTA_Config} , M _limit )) can only be 4, 6, 7, or 8, so the base station 100 only needs to notify the terminal 200 of 2 bits of information. As a result, the number of bits notified to the terminal 200 can be reduced compared to the number of bits required for notifying the set of UL-DL Configurations that can be changed (3n (n ≥ 2) bits).

Furthermore, in the above embodiment, considering that M _limit = 8, and as shown in FIG5 , the maximum number of DL HARQ processes (M _HARQ ) specified in four of the seven UL-DL Configurations (Config #2 to #5) is greater than 8 (M _limit ), and there are multiple UL-DL Configurations that can be changed by eIMTA, the calculation result of min(max(M _{DL _HARQ , eIMTA_Config} , M _limit )) shown in equation (2) is likely to be 8 in most cases. Therefore, the base station 100 may not notify the terminal 200 configured with TDD eIMTA of the set of changeable UL-DL Configurations or the calculation result of min(max(M _{DL _HARQ , eIMTA_Config} , M _limit )), and the terminal 200 may always calculate the IR buffer size (N _IR ) as min(max(M _{DL _HARQ , eIMTA_Config} , M _limit )) = 8. That is, when TDD eIMTA is not configured, terminal 200 can calculate the IR buffer size according to equation (1). When TDD eIMTA is configured, terminal 200 can calculate the IR buffer size according to equation (3) below. In this case, no signaling is sent to terminal 200, such as the set of changeable UL-DL Configurations or the calculation result of min(max(M _{DL _HARQ , eIMTA_Config} , M _limit )). Terminal 200 can continue the DL HARQ process before and after the UL-DL Configuration is changed.

In the above embodiment, the soft buffer is divided using the smaller value of M _{DL_HARQ , eIMTA_Config} , and M _limit according to equations (1) to (3). However, this is not limiting. For example, terminal 200 may not use M _limit as the threshold, but may divide the soft buffer using max(M _{DL_HARQ , eIMTA_Config} ).

In addition, in the above embodiment, the case where M _limit = 8 shown in equations (1) to (3) is described. This case is, for example, the value corresponding to the maximum number of DL HARQ processes that the base station (eNB) can handle in the FDD system. However, the value of M _limit is not limited to 8. In particular, in the TDD system, the maximum number of DL HARQ processes that the base station 100 can handle is greater than the maximum number of DL HARQ processes that the base station can handle in the FDD system (8). For example, in UL-DL Config#5, the maximum number of DL HARQ processes that the base station 100 can handle is 15. Therefore, the value of M _limit only needs to be a value that does not exceed the number of DL HARQ processes that the base station 100 can handle.

In addition, in the expression of the above embodiment, the IR buffer is "reset" when the DL HARQ process is not continued. However, the IR buffer does not need to be actually reset (flash), as long as the downlink data stored in the IR buffer is not read out and used for decoding. Therefore, it is sufficient to notify whether it is the first transmission in the DL HARQ process corresponding to the IR buffer. In addition, the signal indicating whether it is the first transmission or the retransmission is notified by the NDI (New Data Indicator) in the allocation information (i.e., DL assignment) of the downlink data. In the DL assignment indicating the downlink data in the DL HARQ process corresponding to the IR buffer, if the NDI is the inverted value of the last reception, it indicates the first transmission, and if it is not the inverted value, it indicates the retransmission.

Furthermore, in the above-mentioned embodiment, each antenna has been described, but the present invention is also applicable to an antenna port.

An antenna port is a logical antenna composed of one or more physical antennas. In other words, an antenna port does not necessarily refer to a single physical antenna, but may refer to an array antenna composed of multiple antennas.

For example, in LTE, it is not specified how many physical antennas constitute an antenna port, but an antenna port is specified as the minimum unit by which a base station can transmit different reference signals.

In addition, an antenna port may be defined as a minimum unit by which a weight of a precoding vector is multiplied.

Furthermore, in the above-mentioned embodiment, the case where the present invention is configured by hardware has been described as an example, but the present invention can also be realized by software in cooperation with hardware.

In addition, the functional blocks used in the description of the above embodiments are generally implemented as LSIs (integrated circuits). These functional blocks can be integrated individually into a single chip, or some or all of them can be integrated into a single chip. Although referred to as LSI here, it can also be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Furthermore, integrated circuits are not limited to LSIs; dedicated circuits or general-purpose processors can also be used. FPGAs (Field Programmable Gate Arrays) that can be programmed after LSI fabrication, or reconfigurable processors that allow the connections and settings of circuit cells within the LSI to be reconfigured, can also be used.

Furthermore, if new integrated circuit technologies that can replace LSIs emerge with advances in semiconductor technology or the emergence of other technologies derived from them, it would be possible to utilize these technologies to integrate functional blocks. There is also the possibility of applying biotechnology, etc.

As described above, the terminal device of the above embodiment is capable of setting and changing the composition pattern of the subframes constituting one frame, wherein the composition pattern includes a downlink communication subframe for downlink communication and an uplink communication subframe for uplink communication, and the structure adopted by the terminal device comprises: a decoding unit that stores the downlink link data sent from the base station device in a buffer for retransmission and decodes the downlink link data; and a sending unit that sends a response signal generated using the error detection result of the downlink link data, and divides the buffer into a plurality of areas for each retransmission process based on the maximum value of the number of retransmission processes specified for the multiple composition patterns that can be set for the terminal device.

In the terminal device of the above embodiment, each retransmission process in the first configuration mode is allocated to each area of the first area group whose number is the first retransmission process number specified in the first configuration mode currently set for the terminal device.

In the terminal device of the above embodiment, when the number of the first retransmission processes is smaller than the number of the plurality of regions, any one of the retransmission processes in the first configuration pattern is allocated to the remaining second region groups among the plurality of regions other than the first region group.

Furthermore, in the terminal device of the above embodiment, a number of retransmission processes corresponding to the difference between the number of the plurality of regions and the first number of retransmission processes is allocated to each region of the second region group.

In the terminal device of the above embodiment, the entire second area group is re-divided into areas whose number is the same as the first retransmission processes, and all retransmission processes in the first configuration pattern are allocated to each of the re-divided areas.

Furthermore, in the terminal device of the above embodiment, only one retransmission process in the first configuration pattern is allocated to the second area group.

In addition, in the terminal device of the above-mentioned embodiment, when the number of the first retransmission processes is less than the number of the multiple areas, the retransmission processes allocated to the areas within the second area group in the retransmission processes in the second configuration mode last set for the terminal device continue to be allocated in the remaining second area groups other than the first area group among the multiple areas.

Furthermore, in the terminal device of the above embodiment, only one retransmission process in the second configuration pattern is allocated to the second area group.

In addition, in the terminal device of the above-mentioned embodiment, in each of the plurality of configuration patterns, the retransmission processes having a number equal to the number of retransmission processes specified for each configuration pattern are numbered in ascending order starting from the same first number, and in each of the third regional group, whose number among the plurality of regions is equal to the minimum value of the number of retransmission processes specified for the plurality of configuration patterns, the retransmission processes having a number equal to the minimum value are fixedly associated in ascending order starting from the first number up to the second number in each of the plurality of regions, and the retransmission processes having a number equal to the difference between the number of the plurality of regions and the minimum value are fixedly associated in ascending order starting from the third number next to the second number in each of the plurality of regions, and the retransmission processes having a number equal to the difference between the number of the plurality of regions and the minimum value are fixedly associated in each of the fourth regional group, whose number is equal to the third number next to the second number, and the retransmission processes having a number equal to the difference among the first to second retransmission processes are fixedly associated.

In the terminal device of the above embodiment, the number of the plurality of areas is a smaller value between the maximum value and a predetermined threshold value.

In addition, the buffer partitioning method of the above-mentioned embodiment is used for a terminal device that can set and change the configuration pattern of the subframes constituting one frame, the configuration pattern including a downlink communication subframe for downlink communication and an uplink communication subframe for uplink communication, and the buffer partitioning method has the following steps: a step of storing downlink data sent from a base station device in a buffer for retransmission; a step of decoding the downlink data; and a step of sending a response signal generated using the error detection result of the downlink data, based on the maximum value of the number of retransmission processes specified for the multiple configuration patterns that can be set for the terminal device, the buffer is divided into multiple areas for each retransmission process.

The disclosure of Japanese Patent Application No. 2012-159759 filed on July 18, 2012 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

Industrial Applicability

The present invention is useful for mobile communication systems and the like.

Label Description

100 base stations

200 Terminal

101, 208 control unit

102 Control information generation unit

103, 105 coding unit

104, 107 modulation units

106 Data transmission control unit

108 mapping units

109, 218 IFFT units

110, 219 CP additional units

111, 222 wireless transmission unit

112, 201 wireless receiving unit

113, 202 CP removal unit

114 PUCCH extraction unit

115 Despreading Unit

116 Sequence Control Unit

117 related processing units

118 A/N judgment unit

119 Bundled A/N Despreading Unit

120 IDFT units

121 Bundled A/N determination unit

122 Retransmission control signal generation unit

203 FFT unit

204 Extraction Unit

205, 209 demodulation unit

206, 210 decoding unit

207 Judgment Unit

211 CRC unit

212 Response signal generation unit

213 Coding and Modulation Unit

214 Primary Spread Spectrum Unit

215 Secondary Spread Spectrum Unit

216 DFT units

217 Spread Spectrum Unit

220 time division multiplexing unit

221 Selection Unit

Claims (28)

1. A terminal device, comprising: The receiving unit receives information sent by a higher layer, the information representing one of multiple uplink/downlink configurations defining the structure of downlink and uplink subframes in a frame, which is set by the terminal device and can be changed in time-division duplex (TDD) enhanced downlink-uplink interference management and service adaptation; and The decoding unit stores the received data into a soft buffer with a size of 1 transport block, the size of which is calculated based on the smaller of the maximum number of downlink hybrid automatic repeat request processes for the uplink/downlink configuration that can be set and the allowable value. 2. The terminal device as described in claim 1, The receiving unit receives the information sent by the Radio Resource Control layer. 3. The terminal device as described in claim 1, The maximum value is the maximum number of downlink line maximum mixed automatic retransmission request processes associated with the multiple configurable uplink/downlink configurations. 4. The terminal device as described in claim 1, The terminal device supports TDD-enhanced downlink-uplink interference management and service adaptation. 5. The terminal device as described in claim 1, The same size of each transport block is calculated regardless of changes in the uplink/downlink configuration that can be set. 6. The terminal device as described in claim 1, The uplink/downlink configurations that can be set are the same in the cell. 7. The terminal device as described in claim 1, The allowable value is 8. 8. The terminal device as described in claim 1, The maximum number of downlink hybrid automatic repeat request processes that can be configured for uplink/downlink is greater than 8, and the allowable value is 8. The size of each transport block is calculated based on 8. 9. The terminal device as described in claim 1, The configurable uplink/downlink configuration is 3 out of 7 uplink/downlink configurations. 10. The terminal device as described in claim 1, The soft buffer is divided into the size of each transport block. 11. The terminal device as described in claim 1, The decoding unit combines the received data stored in the soft buffer with the retransmitted received data and then decodes it. 12. The terminal device as described in claim 1, The size of each transmission block is calculated using the following formula (1). N_{_IR} is the size of each transport block, N_{_soft} is the capacity of the soft buffer, K_c is the number of downlink component carriers supported by the terminal device, K_{_MIMO} is the number of multiplexing layers supported by the terminal device, M _{_{DL_HARQ,eIMTA_Config}} is the maximum number of downlink hybrid automatic repeat request processes that can be configured for uplink/downlink, and M_{_limit} is the allowable value. 13. A communication device, comprising: The setting unit sets a configurable uplink/downlink configuration for calculating the soft buffer size for each transmission block in the terminal. This uplink/downlink configuration is one of multiple uplink/downlink configurations that define the structure of downlink and uplink subframes in a frame, and is configurable relative to the terminal and changeable in Time Division Duplex (TDD) enhanced downlink-uplink interference management and service adaptation. The transmitting unit sends information from the higher layer indicating the configurable uplink/downlink configuration. The soft buffer size for each transport block is calculated based on the maximum number of downlink hybrid automatic repeat request processes for the uplink/downlink configuration that can be set, and the smaller of the allowable values. 14. The communication device as claimed in claim 13, The transmitting unit transmits the information using the radio resource control layer. 15. The communication device as claimed in claim 13, The maximum value is the maximum number of downlink line maximum mixed automatic retransmission request processes associated with the multiple configurable uplink/downlink configurations. 16. The communication device as claimed in claim 13, The terminal supports TDD-enhanced downlink-uplink interference management and service adaptation. 17. The communication device as claimed in claim 13, The same size of each transport block is calculated regardless of changes in the uplink/downlink configuration that can be set. 18. The communication device as claimed in claim 13, The uplink/downlink configurations that can be set are the same in the cell. 19. The communication device as claimed in claim 13, The allowable value is 8. 20. The communication device as claimed in claim 13, The maximum number of downlink hybrid automatic repeat request processes that can be configured for uplink/downlink is greater than 8, and the allowable value is 8. The soft buffer size for each transport block is calculated based on 8. 21. The communication device as claimed in claim 13, The configurable uplink/downlink configuration is 3 out of 7 uplink/downlink configurations. 22. The communication device as claimed in claim 13, The soft buffer of the terminal is divided into soft buffer sizes for each transmission block. 23. The communication device as claimed in claim 13, The sending unit sends data to the terminal, and if the communication device receives a NACK for the data from the terminal, the sending unit retransmits the data to the terminal. 24. The communication device as claimed in claim 13, The size of the soft buffer for each transmission block is calculated using the following formula (1). N _{_IR} is the soft buffer size of each transport block, N _{_soft} is the soft buffer capacity, K_c is the number of downlink component carriers supported by the terminal, K_{_MIMO} is the number of multiplexing layers supported by the terminal, M _{_{DL_HARQ,eIMTA_Config}} is the maximum number of downlink hybrid automatic repeat request processes that can be configured for uplink/downlink, and M_{_limit} is the allowable value. 25. A communication method, including the following steps: The process of receiving information sent from a higher layer, the information representing one of multiple uplink/downlink configurations defining the structure of downlink and uplink subframes in a frame, which is set by the terminal and can be changed in time division duplex (TDD) enhanced downlink-uplink interference management and service adaptation; and The process of storing received data into a soft buffer with a size of 1 transport block, the size of which is calculated based on the smaller of the maximum number of downlink hybrid automatic repeat request processes for the uplink/downlink configuration that can be set, and an allowable value. 26. A communication method, including the following steps: The process of setting a configurable uplink/downlink configuration for calculating the soft buffer size for each transmission block in the terminal, wherein the uplink/downlink configuration is one of multiple uplink/downlink configurations that define the structure of downlink and uplink subframes in a frame, and is configurable relative to the terminal and changeable in time-division duplex (TDD) enhanced downlink-uplink interference management and service adaptation; and The process of sending information from a higher layer indicating the configurable uplink/downlink configuration. The soft buffer size for each transport block is calculated based on the maximum number of downlink hybrid automatic repeat request processes for the uplink/downlink configuration that can be set, and the smaller of the allowable values. 27. Integrated circuits control the following processes: Processing of receiving information sent by higher layers, the information representing one of multiple uplink/downlink configurations defining the structure of downlink and uplink subframes in a frame, and a configuration that can be set by the terminal and changed in Time Division Duplex (TDD) enhanced downlink-uplink interference management and service adaptation; and The process of storing received data into a soft buffer with a size of 1 transport block, the size of which is calculated based on the smaller of the maximum number of downlink hybrid automatic repeat request processes for the uplink/downlink configuration that can be set, and an allowable value. 28. Integrated circuits control the following processes: The process involves setting a configurable uplink/downlink configuration for calculating the soft buffer size per transport block in the terminal. This uplink/downlink configuration is one of multiple uplink/downlink configurations that defines the structure of downlink and uplink subframes within a frame, and is configurable relative to the terminal and changeable in Time Division Duplex (TDD) enhanced downlink-uplink interference management and service adaptation. The processing involves sending information from higher layers indicating the configurable uplink/downlink configuration. The soft buffer size for each transport block is calculated based on the maximum number of downlink hybrid automatic repeat request processes for the uplink/downlink configuration that can be set, and the smaller of the allowable values.