Integrated circuit for controlling user apparatus

Abstract

To use multiple subframe allocation while providing a minimum unit of efficient control information.SOLUTION: The present disclosure relates to codeword activation / deactivation in multi-subframe grant. Specifically, even in a case where other control parameters including resource allocation are executed for a plurality of subframes, it is possible to activate / deactivate a codeword dynamically and in units of subframe. A signal from a scheduling entity to a scheduled entity includes control information including common resource grant for a plurality of subframes and a plurality of codewords of each subframe, and codeword indication information indicating activation / deactivation of the codeword of each of the plurality of subframes. For each subframe, it is determined whether or not the codeword in the subframe is enabled or disabled according to the codeword indication information and / or which codeword is enabled or disabled.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to signaling of scheduling information in a communication system having a plurality of subframes, and more particularly, to an apparatus, a method, and a signal for performing such signaling.

Background Art

[0002] [Long Term Evolution (LTE)] The third-generation mobile communication system (3G) based on WCDMA (registered trademark) radio access technology is being deployed on a wide scale around the world. As a first step in enhancing or evolving this technology, High-Speed Downlink Packet Access (HSDPA) and Enhanced Uplink (also referred to as High-Speed Uplink Packet Access (HSUPA)) have been introduced, thereby providing a highly competitive radio access technology.

[0003] To meet the increasing demands from users and to ensure competitiveness for new radio access technologies, the 3GPP (registered trademark) introduced a new mobile communication system called Long Term Evolution (LTE). LTE is designed to provide carriers required for high-speed transmission of data and media and for supporting large-capacity voice over the next 10 years. The ability to provide a high bit rate is an important strategy in LTE.

[0004] The LTE system is a packet-based efficient radio access and radio access network that provides all IP-based functions with low latency and low cost. In LTE, scalable multiple transmission bandwidths (e.g., 1.4 MHz, 3.0 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz, and 20.0 MHz) are specified to achieve flexible system deployment using a given spectrum. For the downlink, OFDM (Orthogonal Frequency Division Multiplexing)-based radio access is adopted because such radio access is essentially less susceptible to multipath interference (MPI) due to its low symbol rate, uses a cyclic prefix (CP), and can also support various transmission bandwidth configurations. For the uplink, SC-FDMA (Single-Carrier Frequency Division Multiple Access)-based radio access is adopted because, considering the limited transmission output of user equipment (UE), providing a wider coverage area is prioritized over improving peak data rate. In LTE Release 8 / 9, many major packet radio access technologies (e.g., MIMO (Multiple Input Multiple Output) channel transmission technology) are adopted, and a highly efficient control signaling structure is achieved.

[0005] [LTE Architecture] Figure 1 shows the overall architecture of LTE. E-UTRAN is composed of eNodeBs, and an eNodeB terminates the user plane (PDCP / RLC / MAC / PHY) protocol and control plane (RRC: Radio Resource Control) protocol of E-UTRA towards user equipment (UE). An eNodeB (eNB) hosts the physical (PHY) layer, medium access control (MAC) layer, radio link control (RLC) layer, and packet data control protocol (PDCP) layer (these layers include functions for header compression and encryption of the user plane). The eNB also provides the radio resource control (RRC) function corresponding to the control plane. The eNB performs many functions such as radio resource management, admission control, scheduling, implementation of uplink service quality (QoS: Quality of Service) through negotiation, broadcast of cell information, encryption / decryption of user plane data and control plane data, compression / decompression of downlink / uplink user plane packet headers, etc. The radio resource control (RRC) layer controls the communication between the UE and the eNB over the radio interface and the mobility of the UE moving across several cells. The RRC protocol also supports the transmission of NAS information. For a UE in RRC_IDLE, the RRC supports notification of incoming calls from the network. RRC connection control covers all procedures related to the establishment, modification, and release of the RRC connection (including paging, measurement setup and reporting, radio resource setup, initial security activation, establishment of signalling radio bearers (SRBs) and radio bearers for transmitting user data (data radio bearers (DRBs))). Multiple eNodeBs are connected to each other through the X2 interface.

[0006] In addition, multiple eNodeBs are connected to the EPC (Evolved Packet Core) via the S1 interface, more specifically, to the MME (Mobility Management Entity) via the S1-MME and to the Serving Gateway (SGW) via the S1-U. The S1 interface supports a many-to-many relationship between the MME / Serving Gateway and the eNodeB. The SGW routes and forwards user data packets while functioning as the user plane mobility anchor during handover between eNodeBs. Further, the SGW functions as an anchor for mobility between LTE and another 3GPP technology (terminating the S4 interface and relaying traffic between the 2G / 3G system and the PDN GW). The SGW terminates the downlink data path for idle user equipment and triggers paging when downlink data arrives for that user equipment. The SGW manages and stores the context of the user equipment (e.g., parameters of the IP bearer service or internal network routing information). Further, the SGW performs duplication of user traffic in the case of lawful interception.

[0007] The MME is the main control node of the LTE access network. The MME is responsible for the tracking and paging procedures (including retransmission) of idle-mode user equipment. The MME is involved in the bearer activation / deactivation process. Furthermore, the MME also plays a role in selecting the SGW of the user equipment at the first attachment and during LTE intra-handover with relocation of core network (CN) nodes. The MME is responsible for authenticating the user (by interacting with the HSS). Non-Access Stratum (NAS) signaling is terminated at the MME. The MME also plays a role in generating and assigning a temporary ID to the user equipment. The MME checks the authentication of the user equipment for entry into the service provider's PLMN (Public Land Mobile Network) and enforces the roaming restrictions of the user equipment. The MME is the termination point within the network for the encryption / integrity protection of NAS signaling and manages the security keys. Signaling eavesdropping is also supported by the MME. Additionally, the MME provides control plane functions for mobility between the LTE access network and 2G / 3G access networks and terminates the S3 interface from the SGSN. Furthermore, the MME terminates the S6a interface towards the home HSS for roaming user equipment.

[0008] [Component Carrier Structure in LTE] The downlink component carrier of the 3GPP LTE system is further divided in the time-frequency domain in a so-called subframe. In 3GPP LTE, each subframe is divided into two downlink slots as shown in Fig. 2A. The first downlink slot includes a control channel region (PDCCH region) within the first OFDM symbol. Each subframe is composed of a given number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release 8)), and each OFDM symbol spreads over the entire bandwidth of the component carrier. Thus, each of the OFDM symbols is composed of several modulation symbols transmitted on each subcarrier. In LTE, the transmission signal in each slot is described by an N DL RB ×N RB sc resource grid of this number of subcarriers and N DL symb number of OFDM symbols. N DL RB is the number of resource blocks in the bandwidth. N DL RB depends on the downlink transmission bandwidth set in the cell, and N min,DL RB ≦N DL RB ≦N max,DL RB is satisfied. In this case, N min,DL RB = 6 and N max,DL RB = 110 are the minimum downlink bandwidth and the maximum downlink bandwidth supported by the current version of the specification, respectively. N RB sc is the number of subcarriers in one resource block. In the case of a normal cyclic prefix subframe structure, N RB sc = 12, N DL symb = 7. In the case of the uplink, the grid shown in Fig. 2B is provided. In this regard, also refer to Figs. 6.2.2-1 and 5.2.1-1 of Non-Patent Document 1.

[0009] For example, assuming a multi-carrier communication system that uses, for example, OFDM as used in 3GPP LTE, the minimum unit of resources that can be allocated by a scheduler is one "resource block". A physical resource block (PRB) is defined as a continuous OFDM symbol (e.g., 7 OFDM symbols) in the time domain and a continuous sub-carrier (e.g., 12 sub-carriers of a component carrier) in the frequency domain, as illustrated in FIG. 2. Therefore, in 3GPP LTE (Release 8), a physical resource block is composed of resource elements and corresponds to one slot in the time domain and 180 kHz in the frequency domain (for further details regarding the downlink resource grid, see, for example, Section 6.2 of Non-Patent Document 2 (e.g., version 8.9.0, available on the 3GPP website and incorporated herein by reference)).

[0010] One subframe is composed of two slots. When the so-called "normal" CP (Cyclic Prefix) is used, there are 14 OFDM symbols in the subframe, and when the so-called "extended" CP is used, there are 12 OFDM symbols in the subframe. For the purpose of terminology, hereinafter, a time-frequency resource equivalent to the same continuous sub-carriers extending over the entire subframe is called a "resource block pair" or the synonymous "RB pair" or "PRB pair".

[0011] The term "Component Carrier" refers to a combination of several resource blocks in the frequency domain. In future releases of LTE, the term "Component Carrier" will no longer be used, and instead, this terminology will be changed to "Cell", which refers to a combination of downlink resources and optionally uplink resources. The association between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information transmitted in the downlink resources.

[0012] Similar assumptions regarding the structure of component carriers also apply to subsequent releases.

[0013] [Carrier Aggregation in LTE-A for Wider Bandwidth Support] The bandwidth that an LTE-Advanced system can support is 100 MHz, while an LTE system can only support 20 MHz. In carrier aggregation, two or more component carriers are aggregated for the purpose of supporting a wider transmission bandwidth of up to 100 MHz. In an LTE-Advanced system, several cells in an LTE system are aggregated into one wider channel. This channel is wide enough for 100 MHz even if these cells in LTE are in different frequency bands. A user equipment can receive or transmit one or more component carriers (corresponding to multiple serving cells) simultaneously according to the capabilities of the user equipment. Carrier aggregation is supported for both contiguous and non-contiguous component carriers, and each component carrier is limited to a maximum of 110 resource blocks in the frequency domain (using the numerology of 3GPP LTE (Release 8 / 9)).

[0014] When carrier aggregation is configured, the mobile terminal has only one RRC connection with the network. When establishing / re - establishing the RRC connection, one cell provides security inputs (one ECGI, one PCI, and one ARFCN) and non - access stratum (NAS) mobility information (e.g., TAI), similar to LTE Release 8 / 9. After the establishment / re - establishment of the RRC connection, the component carrier corresponding to that cell is referred to as the downlink primary cell (PCell). In the connected state, there is always one downlink PCell (DL PCell) and one uplink PCell (UL PCell) configured per user equipment. Among the set of configured component carriers, other cells are called secondary cells (SCells), and the carriers of the SCells are downlink secondary component carriers (DL SCCs) and uplink secondary component carriers (UL SCCs). Up to five serving cells (including the PCell) can be configured for one UE.

[0015] [Uplink Access Method in LTE] In uplink transmission, in order to maximize coverage, the user terminal needs to transmit with high power efficiency. As the uplink transmission method of E-UTRA, a method that combines single-carrier transmission and FDMA with dynamic bandwidth allocation has been selected. The main reason for choosing single-carrier transmission is that, compared with multi-carrier signals (OFDMA), the peak-to-average power ratio (PAPR) is low. Correspondingly, the efficiency of the power amplifier is improved, and the coverage is also improved (the data rate is higher for a given terminal peak power). In each time interval, the eNodeB allocates to the user a unique time / frequency resource for transmitting user data. This ensures orthogonality within the cell. By means of orthogonal multiple access in the uplink, the in-cell interference is eliminated, thereby increasing the spectral efficiency. Regarding the interference caused by multipath propagation, it is addressed at the base station (eNodeB) by inserting a cyclic prefix into the transmitted signal.

[0016] The basic physical resource used for data transmission is composed of frequency resources of size BW over one time interval (e.g., subframe) (the encoded information bits are mapped to this resource). Note that the subframe (also referred to as the transmission time interval (TTI)) is the minimum time interval for transmitting user data. However, by concatenating subframes, it is also possible to allocate to the user frequency resources BW over a time longer than 1 TTI. grant grant

[0017] [Layer 1 / Layer 2 Control Signaling] ​​For the purpose of notifying the user to be scheduled of the user's allocation status, transport format, and other transmission-related information (e.g., HARQ information, transmit power control (TPC) commands), L1 / L2 control signaling is transmitted in the downlink together with data. The L1 / L2 control signaling is multiplexed with the downlink data within a subframe (assuming that the user allocation can change on a subframe-by-subframe basis). Note that the user allocation can also be performed on a TTI (transmission time interval) basis. In that case, it should be noted that the TTI length can be an integer multiple of the subframe. The TTI length can be made constant for all users within the service area, or different for different users, or even dynamic for each user. The L1 / L2 control signaling generally needs to be transmitted once per TTI. In the following, without loss of generality, it is assumed that the TTI is equal to one subframe.

[0018] The L1 / L2 control signaling is transmitted on the physical downlink control channel (PDCCH). The PDCCH conveys a message as downlink control information (DCI). The DCI generally contains resource allocation and other control information for the mobile terminal or a group of UEs. Generally, several PDCCHs can be transmitted within one subframe.

[0019] Note that in 3GPP LTE, it should be noted that the allocation for uplink data transmission (also referred to as uplink scheduling grant or uplink resource allocation) is also transmitted on the PDCCH. Furthermore, in Release 11, EPDCCH was introduced, and EPDCCH basically performs the same function as PDCCH (i.e., conveys layer 1 / layer 2 control signaling), but the details of the transmission method are different from those of PDCCH. For further details, see, in particular, the current version of Non-Patent Document 1 (e.g., version 13.2.0) and Non-Patent Document 3 (which is available for free on the 3GPP website and is incorporated herein by reference). Therefore, most of the items outlined in the background art section and the embodiments apply to PDCCH and EPDCCH, or other means of conveying layer 1 / layer 2 control signaling, unless otherwise specified.

[0020] The information sent by L1 / L2 control signaling for the purpose of allocating uplink radio resources or downlink radio resources (especially in LTE(-A) Release 10) can generally be classified into the following items. - User Identity: Indicates the user to whom the allocation is to be made. This information is generally included in the checksum by masking the CRC with the user's identification information. - Resource allocation information: Indicates the resources (e.g., resource blocks (RB)) allocated to the user. This information is also referred to as resource block assignment (RBA). Note that the number of resource blocks (RB) allocated to the user can be dynamic. - Carrier indicator: Used when the control channel transmitted on the first carrier allocates resources related to the second carrier (i.e., the resources of the second carrier or resources related to the second carrier) (cross-carrier scheduling). - Modulation and Coding Scheme: Determines the modulation method and coding rate to be adopted. - HARQ Information: Such as a New Data Indicator (NDI) or Redundancy Version (RV), which is particularly useful when retransmitting a data packet or a part thereof. - Power Control Command: Adjusts the transmission power when transmitting uplink data or control information to be allocated. - Reference Signal Information: Such as the applied cyclic shift or Orthogonal Cover Code (OCC) index used for transmitting or receiving the reference signal to be allocated. - Uplink Allocation Index or Downlink Allocation Index: Used to identify the order of assignment, and is particularly useful in a TDD system. - Hopping Information: For example, information indicating whether to apply resource hopping for the purpose of increasing frequency diversity and the application method. - CSI Request: Used to trigger the transmission of Channel State Information in the allocated resources. - Multi-cluster Information: A flag used to indicate and control whether to perform transmission in a single cluster (a continuous set of RBs) or a multi-cluster (at least two discontinuous sets of continuous resource blocks). Multi-cluster allocation was introduced by 3GPP LTE-(A) Release 10.

[0021] Note that the above list does not cover all, and it should be noted that depending on the DCI format used, it is not necessary to include all the listed information items in each PDCCH transmission.

[0022] In the current LTE specification (Release 13), the modulation and coding scheme (MCS) is determined by the modulation order, which is a parameter, the transport block size (TBS), and the number of resource elements (REs) used for transmitting the transport block.

[0023] The modulation orders (number of bits per modulation symbol) supported in LTE in licensed bands include 2, 4, 6, and 8, corresponding to QPSK, 16QAM, 64QAM, and 256QAM, respectively. Whether all of these are supported in unlicensed band operation has not been examined to date, but it would be advantageous if the same set of modulation orders were supported in unlicensed band operation as well.

[0024] As described in Section 7.1.7 of Non-Patent Document 3 (available on the 3GPP website), the transport block size (TBS) is determined by the TBS index according to the MCS index indicated to the UE in the DCI and the number of physical resource blocks (PRBs) allocated for PDSCH transmission. This LTE specification (Non-Patent Document 3) includes a two-dimensional TBS table in Section 7.1.7.2, where the TBS index indicates the rows and the number of scheduled PRBs indicates the columns. This table defines the transport block size (and thus the applicable coding and puncturing).

[0025] FIG. 5 shows an uplink MCS table that assigns MCS and / or redundant versions to 32 values from 0 to 31. Specifically, the first column represents the MCS index included in the DCI. Each of the MCS indices 0 to 28 is associated with a specific combination of modulation order (2 = QPSK, 4 = 16QAM, 6 = 64QAM), transport block size (TBS) index, and redundant version index. The MCS indices (values) 29 to 31 are not associated with a specific modulation (order) or coding scheme (TBS index) in the uplink, and define redundant versions 1 to 3. In this case, it is assumed that the modulation and coding scheme remains the same as that of the transmission of the same transport block before (e.g., redundant version 0).

[0026] The redundant version (RV) specifies the starting point in the cyclic (re)transmission buffer for starting the read operation. For the first transmission mainly for sending systematic bits, usually RV = 0 is selected because this method shows a good compromise between normal decoding at high signal-to-noise ratio (SNR) and normal decoding at low SNR. The scheduler can select different RVs for the transmission of the same packet to support both IR (incremental redundancy) combining and Chase combining. Currently, four redundant versions are defined, and each redundant version is characterized by its starting position and numbered from 0 to 3. The normal order of these RVs in the first transmission and subsequent retransmissions is 0, 2, 3, 1.

[0027] Downlink control information takes several formats. These formats differ in the overall size and the information contained in the fields described above. The various DCI formats currently defined in LTE are as follows and are described in detail in Section 5.3.3.1 of Non-Patent Document 4 (current version 13.2.0, available on the 3GPP website and incorporated herein by reference). Further details regarding the DCI format and the specific information transmitted in DCI can be found in the technical standards listed above or in Section 9.3 of Non-Patent Document 5 (incorporated herein by reference). - Format 0: DCI Format 0 is used for transmitting resource grants for PUSCH using single-antenna port transmission in uplink transmission mode 1 or 2. - Format 1: DCI Format 1 is used for transmitting resource allocations for single-codeword PDSCH transmission (downlink transmission modes 1, 2, 7). - Format 1A: DCI Format 1A is used for the purpose of compactly signaling resource allocations for single-codeword PDSCH transmission and for allocating dedicated preamble signatures to mobile terminals for collision-free random access (all transmission modes). - Format 1B: DCI Format 1B is used to compactly signal resource allocations for PDSCH transmission (downlink transmission mode 6) using closed-loop precoding with rank-1 transmission. The information transmitted is the same as that of Format 1A, but in addition thereto, an indicator of the precoding vector applied to the PDSCH transmission is included. - Format 1C: DCI Format 1C is used to transmit PDSCH allocations in a very compact manner. When Format 1C is used, PDSCH transmission is restricted to the use of QPSK modulation. This format is used, for example, to signal paging messages or broadcast system information messages. - Format 1D: DCI Format 1D is used to compactly signal resource allocations for PDSCH transmission using multi-user MIMO. The information transmitted is the same as in the case of Format 1B, except that instead of one of the bits of the precoding vector indicator, there is one bit to indicate whether a power offset is applied to the data symbols. This feature is necessary to indicate whether the transmission power is shared between two UEs. In future versions of LTE, this feature may be extended for sharing power among a larger number of UEs. - Format 2: DCI Format 2 is used to transmit resource allocations for PDSCH in the case of closed-loop MIMO operation (transmission mode 4). - Format 2A: DCI Format 2A is used to transmit resource allocations for PDSCH in the case of open-loop MIMO operation. The information transmitted is the same as in the case of Format 2, except that, as an exception, there is no precoding information when the eNodeB has two transmit antenna ports, and when there are four antenna ports, two bits are used to indicate the transmission rank (transmission mode 3). - Format 2B: Introduced in Release 9, it is used to transmit resource allocations for PDSCH in the case of dual-layer beamforming (transmission mode 8). - Format 2C: Introduced in Release 10, it is used to transmit resource allocations for PDSCH in the case of closed-loop single-user MIMO operation or multi-user MIMO operation (up to 8 layers) (transmission mode 9). - Format 2D: Introduced in Release 11 and used for transmissions with a maximum of 8 layers. Primarily used in CoMP (Cooperative Multipoint) (transmission mode 10). - Formats 3 and 3A: DCI Formats 3 and 3A are used to transmit power control commands for PUCCH and PUSCH, each having a power adjustment of 2 bits or 1 bit respectively. These DCI formats include individual power control commands for groups of UEs. - Format 4: DCI Format 4 is used for scheduling PUSCH, which uses closed-loop spatial multiplexing transmission in uplink transmission mode 2.

[0028] The PDCCH conveys DCI in a set of one or more consecutive control channel elements (CCEs). A control channel element corresponds to 9 resource element groups (REGs), and each resource element group (REG) consists of 4 or 6 resource elements.

[0029] The search space indicates a series of CCE positions where the UE can find its own PDCCH. Each PDCCH conveys one DCI and is identified by an RNTI (Radio Network Temporary Identifier) implicitly encoded in the CRC added to the DCI. The UE monitors the CCEs in the configured (one or more) search spaces by blindly decoding and checking the CRC.

[0030] The search space can be a common search space and a UE-specific search space. The UE needs to monitor both the common search space and the UE-specific search space (which may overlap). The common search space conveys DCI that is common to all UEs, such as system information (using SI-RNTI), paging (P-RNTI), PRACH response (RA-RNTI), or UL TPC command (TPC-PUCCH / PUSCH-RNTI). The UE-specific search space conveys DCI for UE-specific allocations (using the C-RNTI allocated to the UE), semi-persistent scheduling (SPS C-RNTI), or initial allocations (temporary C-RNTI).

[0031] In conventional wireless communication (single-input single-output (SISO)), preprocessing of transmitted data in the time domain or frequency domain and decoding of received data in the time domain or frequency domain are utilized. However, by using additional antenna elements either on the base station (eNodeB) side or the user equipment (UE) side (in the downlink or uplink), additional spatial dimensions are opened for signal precoding and detection. In space-time processing methods, this dimension is utilized for the purpose of improving the link performance with respect to one or more possible numerical metrics (error rate, communication data rate, coverage area, spectral efficiency (unit: bps / Hz / cell), etc.). Such technologies are classified into single-input multiple-output (SIMO), multiple-input single-output (MISO), or MIMO (multiple-input multiple-output) depending on whether multiple antennas are available at the transmitter and / or receiver. The point-to-point multi-antenna link between a base station and a single UE is called single-user MIMO (SU-MIMO), while multi-user MIMO (MU-MIMO) is characterized by several UEs communicating with a common base station simultaneously using the same frequency domain resources and time domain resources.

[0032] The LTE standard defines so-called "antenna ports" (see Section 5.2.1 of Non-Patent Document 1). Antenna ports are logical entities distinguished by their reference signal sequences rather than corresponding to physical antennas. Multiple antenna port signals can be transmitted by a single transmitting antenna. Correspondingly, one antenna port can be spread over multiple transmitting antennas.

[0033] "Spatial layer" is a term used in LTE and represents one of the different streams generated by spatial multiplexing. A layer can be described as the mapping of symbols to transmission antenna ports. Each layer is identified by a precoding vector of a size equal to the number of transmission antenna ports and can be associated with a radiation pattern. The transmit rank is the number of layers being transmitted.

[0034] A "codeword" is an independently encoded data block corresponding to one transport block (TB) passed from the medium access control (MAC) layer of the transmitter to the physical layer and is protected by a cyclic redundancy check (CRC). In the case of two or more ranks, two codewords can be transmitted. The number of codewords is always less than or equal to the number of layers, and the number of layers is always less than or equal to the number of antenna ports. It is possible to map transport block 1 to codeword 0 and transport block 2 to codeword 1, or transport block 2 to codeword 0 and transport block 1 to codeword 1.

[0035] For the purpose of enabling rapid adaptation of the rank and precoder in the downlink transmission mode, it is possible to configure the UE to feedback the rank indicator (RI: Rank Indicator) together with the precoding matrix indicator (PMI: Precoding Matrix Indicator) (these indicate the preferred RI / PMI based on the measured quality). On the other hand, the eNB indicates whether it is applying the UE's preferred precoder via the transmitted precoding matrix indicator (TPMI: Transmitted Precoding Matrix Indicator) in the downlink allocation message on the PDCCH, and if not, which precoder is being used. This enables the UE to derive the correct phase reference for the cell-specific reference signal for the purpose of demodulating the PDSCH data.

[0036] Similarly, the eNB can control the rank and precoder in the uplink transmission mode. Different from the downlink, there is no explicit feedback from the UE such as RI and PMI. The eNB obtains the transmitted reference symbols (such as demodulation reference symbols or sounding reference symbols) from the uplink transmission, determines the appropriate number of layers to be transmitted and the TPMI using these reference signals, and indicates them in the uplink resource allocation message (DCI) transmitted on the control channel such as the PDCCH.

[0037] [LTE in Unlicensed Band: License-Assisted Access LAA] Work items to address LTE specifications for unlicensed band operation were initiated in June 2015. The reason for extending LTE to unlicensed bands is that, in addition to the limited amount of licensed bands, the demand for wireless broadband data is growing increasingly. Therefore, unlicensed frequency bands are increasingly being regarded as a supplementary means for mobile phone operators to expand their own service offerings. When compared to relying on other radio access technologies (RATs) such as Wi-Fi, the advantage of LTE in unlicensed bands is that operators and vendors can utilize existing and future investments in LTE / EPC hardware in the radio / core network by supplementing the LTE platform through access to unlicensed frequency bands.

[0038] However, access to unlicensed frequency bands will inevitably coexist with other radio access technologies (RATs) in unlicensed frequency bands, so it must be considered that the quality cannot absolutely match that of licensed frequency band access. Therefore, LTE operation in unlicensed bands will, at least initially, not be considered as a standalone operation in unlicensed frequency bands but rather as a supplement to LTE in licensed frequency bands. Based on this assumption, 3GPP established the term Licensed Assisted Access (LAA) for operating LTE in unlicensed bands in combination with at least one licensed band. However, the future standalone operation of LTE in unlicensed frequency bands without relying on Licensed Assisted Access (LAA) is not excluded.

[0039] The current common LAA method in 3GPP is to make the most of the already established Release 12 carrier aggregation (CA) framework. As described above, the configuration of the carrier aggregation (CA) framework includes a so-called primary cell (PCell) carrier and one or more secondary cell (SCell) carriers. In carrier aggregation (CA), generally, both cell self-scheduling (where scheduling information and user data are transmitted on the same carrier) and cross-carrier scheduling between cells (where scheduling information in PDCCH / EPDCCH and user data in PDSCH / PUSCH are transmitted on different carriers) are supported.

[0040] In the basic method assumed in 3GPP, the PCell is operated in a licensed band, while one or more SCell are operated in an unlicensed band. The advantage of this approach is that the PCell can be used to transmit control messages and user data that requires high service quality (QoS) (such as voice and video) with high reliability. On the other hand, since SCell in the unlicensed frequency band inevitably coexists with other radio access technologies (RAT), the QoS may be significantly reduced to varying degrees depending on the scenario. Figure 3 shows a very basic scenario, where there are a licensed PCell, a licensed SCell 1, and various unlicensed SCell 2, 3, 4 (depicted as small cells for illustration). The transmit / receive network nodes of the unlicensed SCell 2, 3, 4 can be remote radio heads managed by the eNB or nodes that are attached to the network but not managed by the eNB. For simplicity, the connections from these nodes to the eNB or the network are not explicitly shown in the figure.

[0041] In the initial stage, it was agreed in 3GPP that the study and specifications of LAA (License Assisted Access) should focus on the unlicensed bands at 5 GHz. Therefore, one of the most important issues is coexistence with Wi-Fi (IEEE 802.11) systems operating in these unlicensed bands. To support fair coexistence between LTE and other technologies (such as Wi-Fi), and to ensure fairness among multiple different LTE operators in the same unlicensed band, the LTE channel access procedure for unlicensed band operation must follow a specific set of regulations determined by the region (Europe, the United States, China, Japan, etc.) and the frequency bands under consideration. A comprehensive description of the regulatory requirements for operation in the 5 GHz unlicensed band is described in Non-Patent Document 6 (available on the 3GPP website). The regulatory requirements that must be considered when designing the LAA procedure include, depending on the region and band, Dynamic Frequency Selection (DFS), Transmit Power Control (TPC), Listen Before Talk (LBT), and discontinuous transmission with a limited maximum transmission time. The intention of 3GPP is to aim for a single international framework for LAA, that is, basically, when designing the system, all requirements regarding various regions and the 5 GHz band must be considered.

[0042] The operation of DFS (Dynamic Frequency Selection) and the corresponding requirements are related to the master / slave principle. For the purpose of performing radar detection, the master detects radar interference, but at this time, it can rely on another device associated with the master. The device must perform a Clear Channel Assessment (CCA) before occupying a wireless channel in accordance with European regulations regarding LBT (Listen Before Talk). For example, transmission on an unlicensed channel is only permitted after the channel is detected as free based on energy detection. The device must monitor the channel for a specific minimum time during CCA. If the detected energy level exceeds the set CCA threshold, the channel is considered occupied. If the channel is classified as free, the device is immediately permitted to transmit. This restricts the maximum duration of transmission for the purpose of promoting fair resource sharing with other devices operating in the same band.

[0043] Energy detection in CCA is performed across the entire channel bandwidth (e.g., 20 MHz in a 5 GHz unlicensed band), i.e., the received power levels of all subcarriers of the LTE OFDM symbols within that channel contribute to the energy level evaluated in the device performing CCA.

[0044] Furthermore, without re-evaluating whether a given unlicensed channel is available (i.e., LBT / CCA), the total time that a device occupies by continuous transmission is defined as the Channel Occupancy Time (see Section 4.8.3.1 of Non-Patent Document 7). The channel occupancy time is in the range of 1 ms to 10 ms, and the maximum channel occupancy time can be, for example, 4 ms as currently defined in Japan. Furthermore, there is also a minimum idle time during which a device is not permitted to occupy the unlicensed channel again after transmitting on it, and the minimum idle time is at least 5% of the previous channel occupancy time. For example, the UE can perform a new CCA at the end of the Idle Period. This transmission behavior is schematically shown in FIG. 4.

[0045] [Multiple sub-frame allocations] In 3GPP RAN1, a study was conducted on the possibility of multi-sub-frame scheduling in uplink LAA (see Non-Patent Document 8). As a result, only per-tti scheduling is permitted, except for semi-persistent scheduling (SPS) and UL grants in TDD UL / DL configuration 0. A downlink grant or an uplink grant received in sub-frame n schedules only one PDSCH or PUSCH in sub-frame n + k (in the case of FDD, k = 0 for downlink and k = 4 for uplink).

[0046] When the scheduled LAA UE receives a UL grant in subframe n, based on the FDD HARQ timing, in order to occupy the channel before starting PUSCH transmission in subframe n+4, it is necessary to perform LBT for the scheduled unlicensed carrier. The eNB cannot predict the result of LTB on the UE side when sending a UL grant in subframe n, and there is no option other than sending a UL grant expecting that the UE will occupy the channel for the PUSCH scheduled in subframe n+4. However, if the UE cannot complete the necessary LBT for uplink transmission in time, the scheduled PUSCH cannot be transmitted in the scheduled subframe. As a result, not only the resources for the UL grant are wasted, but also the UL resources for PUSCH transmission are wasted. LAA UL transmission should be designed to increase the LAA channel access opportunity with less scheduling overhead.

[0047] To increase the channel access opportunity while minimizing the signaling overhead for scheduling PUSCH in the unlicensed carrier, multi-subframe scheduling is considered. In multi-subframe scheduling, when the UE succeeds in LBT, it can transmit PUSCH in one or more subframes in the scheduled subframe with one UL grant. When the DL demand is low but the UL demand is high, it is advantageous to support multi-subframe scheduling to avoid unnecessary DL transmissions for sending UL grants. In this case, not only the signaling overhead for sending UL grants is saved, but also the overall interference with another node is reduced.

Prior Art Documents

Non-Patent Documents

[0048]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0049] An exemplary embodiment that does not limit the present invention provides an apparatus and method that use multiple subframe allocations while still providing an efficient minimum unit (granularity) of control information.

Means for Solving the Problems

[0050] In a general aspect, the technology disclosed herein is an apparatus that receives a resource grant for a plurality of subframes in a communication system, the resource grant for the plurality of subframes and a plurality of codewords of each subframe, precoding indication information common to the plurality of subframes, and a modulation and coding scheme (MCS) indicator that is common to the plurality of granted subframes and individual for each of the plurality of codewords, the MCS indicator taking one of a plurality of values including a value indicating one of a plurality of MCSs and at least one value not indicating an MCS, a transceiver that receives a signal including control information including the MCS indicator, and a processing device configured to determine that a codeword from a plurality of codewords in a plurality of subframes is invalidated when the MCS indicator for at least one of the plurality of codewords has a value not indicating an MCS, and to determine that it is not invalidated otherwise.

[0051] In another general aspect, the technology disclosed herein is an apparatus for receiving resource grants for a plurality of subframes in a communication system, the apparatus comprising: a signal comprising control information including a common resource grant for the plurality of subframes and a plurality of codewords for each subframe, and codeword indication information indicating activation or deactivation of one or more codewords for each of the plurality of subframes; a transceiver configured to receive the signal; and a processing device configured to determine, for each subframe, whether a codeword from the plurality of codewords in that subframe is to be activated or deactivated according to the codeword indication information, and / or which codeword is to be activated or deactivated.

[0052] Note that a general or particular embodiment may be implemented as a signal, a system, a method, an integrated circuit, a computer program, a storage medium, or any optional combination thereof.

[0053] Further benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. These benefits and / or advantages may be obtained individually by the various embodiments and features of the specification and drawings, and it is not necessary to provide all embodiments and features for the purpose of obtaining one or more of such benefits and / or advantages.

[0054] Exemplary embodiments will be described in more detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0055]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 8

Figure 9A

Figure 9B

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Figure 11

DETAILED DESCRIPTION OF THE INVENTION

[0056] A "mobile station", "mobile node", "user terminal", or "user equipment" is a physical entity within a communication network. A single node can have several functional entities. A functional entity means a software module or a hardware module that performs a given set of functions and / or provides a given set of functions to another functional entity of the node or network. A node can have one or more interfaces for attaching the node to a communication device or communication medium, and the node can communicate through these interfaces. Similarly, a network entity can have a logical interface for attaching a functional entity to a communication device or communication medium, and the network entity can communicate with another functional entity or communication partner node through the logical interface.

[0057] The term "radio resource" used in the claims and this application should be understood broadly to mean a physical radio resource (such as a time-frequency resource).

[0058] The term "unlicensed cell" or "unlicensed carrier" used in the claims and this application should be understood broadly as a cell / carrier in an unlicensed frequency band. Correspondingly, the term "licensed cell" or "licensed carrier" used in the claims and this application should be understood broadly as a cell / carrier in a licensed frequency band. These terms should be understood, by way of example, in the context of 3GPP and the work item "Licensed-Assisted Access" as of Release 12 / 13.

[0059] The transport block (TB) transmitted on the physical downlink shared channel (PDSCH) or the physical uplink shared channel (PUSCH) must be prepared before transmitting the PDSCH or PUSCH itself. A specific number of bits (given by the transport block size (TBS)) are taken from a specific HARQ process queue in the MAC layer and passed to the underlying PHY (physical layer) together with the corresponding MAC header.

[0060] As described above in the background section, there is a one-to-one mapping between the codeword and the transport block. Whether transport block 1 is mapped to codeword 0 and transport block 2 is mapped to codeword 1, or transport block 2 is mapped to codeword 0 and transport block 1 is mapped to codeword 1, is known in advance through either a static rule, setting, or a message included in the downlink control information. For the sake of brevity, this description discusses the activation and deactivation of codewords. However, it should be understood that this description applies equally to "transport blocks" as well as "codewords". Thus, embodiments and examples should be understood to apply to transport blocks that are activated / deactivated in addition to, or instead of, codewords that are activated / deactivated.

[0061] Figure 6 shows a table summarizing some of the agreements currently under consideration within 3GPP regarding the dedicated control information (DCI) used for uplink grants applicable to resources granted in an unlicensed carrier. Specifically, the left column lists the fields of the DCI. The middle and right columns show DCI format 0B and DCI format 4B, respectively, and also show the smallest unit that can define that DCI field in the case of a multi-subframe grant. DCI format 0B and DCI format 4B are intended to be attached to the currently used DCI format 0 and DCI format 4.

[0062] DCI format 4 is currently used for PUSCH scheduling in one UL cell in the case of multi-antenna port transmission mode. In particular, for each of the two codewords (transport blocks), it includes the MCS index (5 bits) defined as shown in FIG. 5 and the NDI (1 bit). Further, a 3-bit or 6-bit precoding information field is included to indicate the TPMI and the number of layers.

[0063] In the table, the term "common" means that each field of the DCI applies to all subframes covered by the multi-subframe grant and to all codewords when multi-layer transmission is applied. For example, the resource allocation field defines the resource blocks allocated per subframe and codeword. In this case, the resource block allocation applies to each codeword of the subframe for each of the multiple subframes.

[0064] DCI format 0B and DCI format 4B generally correspond to the above-described DCI format 0 and DCI format 4, but these DCI formats 0B and 4B provide multi-subframe grants. That is, DCI format 0B is applicable to single-antenna port transmission, while DCI format 4B is applicable to multi-antenna port transmission. As can be understood from the table in FIG. 6, DCI format 0B corresponds to only one codeword and does not support multi-antenna transmission, so it does not convey precoding information. In contrast, DCI format 4B supports multi-antenna port transmission and can thus include the characteristics of each layer / codeword. Therefore, the usage of some DCI fields by format 0B and format 4B can be different. In FIG. 6, when there are multiple codewords, a modulation and coding scheme can be advantageously provided for each codeword. However, it is considered unnecessary to provide an MCS for each subframe because the channel quality is unlikely to change so rapidly and essentially, and it is not clear whether the eNB can have such information for the purpose of using sufficient information on channel conditions that change rapidly enough when transmitting DCI. Regarding whether and how to convey precoding information by DCI format 4B, it is not clear at present.

[0065] As can be understood in FIG. 6, some of the fields are provided for each of the plurality of subframes. For example, a new data indicator is required for each subframe because each subframe conveys different data (since different TTIs are mapped to respective subframes), and thus each subframe can be retransmitted individually. Correspondingly, a redundant version is also required on a per-subframe basis. Note that it should be noted that the redundant versions in the legacy DCI of format 0 and format 4 are selected from a set of four defined values. In the table of FIG. 6, the redundant version is an individual field and has 1 bit per subframe. Generally, 1 bit should be sufficient to distinguish between two values of the redundant version because it is presumed that the number of retransmissions in a multi-subframe configuration will be kept low. Since 1 RV (redundant version) bit represents two possible states, currently, it is assumed that the first RV state represents RV0 and the second RV state represents RV2. Note that the table in FIG. 6 only summarizes the current situation under consideration and can still be changed, so it should be noted that this table is merely an example of a new DCI format for multi-subframe grants.

[0066] All fields shown in FIG. 6, except for the "number of scheduled subframes" field, are also applicable to a new DCI format (tentatively referred to as DCI format 0A and DCI format 4B, corresponding generally to DCI format 0 and DCI format 4 respectively) for scheduling resources in an unlicensed carrier for one subframe. Since the resources are allocated for only one subframe, some fields described as "per subframe" in FIG. 6 are applicable only to the subframe shown.

[0067] Regarding multi-layer transmission, in previous releases of LTE, various mechanisms for invalidating codewords were provided. As described above, in the LTE uplink, currently up to four layers are supported. In the setting of 2 (or 3 or more) layer transmission, one codeword can be dynamically invalidated by a specific combination of DCI fields that are rarely used, especially in combination with 2-layer transmission. In particular, in Release 8, it is possible to invalidate downlink codewords by using DCI format 2 and DCI format 2A (in addition to this, format 2B, format 2C, and format 2D introduced in subsequent LTE releases) (there is no MIMO in this release in the uplink). When the MCS index is equal to 0 (I MCS = 0) and the redundancy version is equal to 1 (rv idx = 1), the codeword is invalidated. In this case, the QPSK modulation scheme, which is the most robust modulation scheme that can be set, is assumed to provide sufficient quality so that in most cases not all possible redundancy versions are required. The redundancy version with the value 1 is the last redundancy version in the order 0, 2, 3, 1 of the applied redundancy versions.

[0068] In Release 13, two further possible methods for invalidating codewords were defined. The codeword is invalidated in the case of a specific combination of the MCS index and the number of physical resource blocks (PRBs) in DCI format 4. Specifically, in DCI format 4, when the MCS index is equal to 0 (I MCS = 0) while the number of PRBs is 2 or more (N PRB > 1), the codeword is invalidated. Furthermore, when the MCS index is equal to 28 (I MCS = 28) and the number of PRBs is equal to 1 (N PRB= 1), the codeword is invalidated. These combinations are selected by taking into account the existence of power limitations in the uplink. When the smallest MCS is used, it means that the channel conditions are not particularly good. With only one PRB, higher power can be applied so that normal transmission is possible. However, as the number of PRBs increases, the power is spread out and the probability of correct reception is low. Therefore, when multi-layer transmission is applied, the smallest MCS index is less likely to be used together with a large number of PRBs. On the other hand, in the case of the largest MCS index that defines the MCS, it is very likely that the channel quality is extremely high. Therefore, in such a case of high channel quality, it is less likely that only one PRB is set.

[0069] The invalidation of the codeword is mainly useful when increased coverage or robust retransmission is desired. The UE can adopt beamforming for single codeword transmission for the purpose of increasing the overall coverage. By beamforming for single codeword transmission, the SINR can also be improved, and thus a higher uplink throughput can be obtained compared to single antenna port transmission without beamforming.

[0070] Furthermore, when it is necessary to retransmit only one codeword in the previous multi-codeword transmission, it is advantageous to invalidate the second codeword for the purpose of reducing the interference between codewords.

[0071] However, when applying a multi-subframe grant, these existing solutions may become inappropriate. In particular, by using only an MCS value equal to 0, the coverage of the corresponding PUSCH transmission may be limited. On the other hand, by using only an MCS equal to 28, the throughput of the PUSCH transmission indicated by the multi-subframe (MSF) grant may be limited.

[0072] Considering that only a 1-bit redundant version is currently under consideration for each subframe (see Figure 6), it may not be appropriate to use the redundant version index as a condition. Further, the redundant version is common to both codewords in that subframe. Furthermore, using the number of allocated PRBs as a condition may also not be appropriate in some cases because the resource block allocation is common to all subframes in both codewords. In addition to this, the minimum resource allocation for transmission granted in an unlicensed carrier is currently 10 PRBs.

[0073] For the purpose of overcoming these problems, the present disclosure provides efficient signaling for invalidating codewords by multi-subframe DCI in a multi-layer configuration.

[0074] [Invalidation by MCS Level] In uplink LAA (unlicensed bandwidth), the minimum resource allocation is 10 PRBs. Generally, the minimum resource allocation can be a set multiple of the smallest allocable unit in the system (PRB in LTE). Therefore, the activation / invalidation of one or more codewords can be indicated by a specific MCS field value in combination with a condition regarding the number of allocated PRBs. Such exemplary conditions for invalidation are as follows. - The minimum MCS index (e.g., MCS = 0, the MCS indicating the most robust modulation and coding rate), and the number of allocated PRBs greater than the predefined or pre-set minimum number of allocable PRBs (e.g., in the case of LAA, a number of PRBs greater than 10). - The maximum MCS index (e.g., MCS = 28, the MCS indicating the lowest robustness modulation and coding rate), and the number of allocated PRBs equal to the predefined or pre-set minimum number of allocable PRBs (e.g., in the case of LAA, 10 PRBs are allocated).

[0075] For example, in LAA using single subframe allocation (DCI format 4A), the above invalidation conditions can be adopted to invalidate codewords. In DCI format 4A, the minimum allocation is also 10 PRBs. These conditions can be adapted to multi-subframe allocation (DCI format 4B), and thus, in each subframe scheduled by that DCI, one codeword is determined to be invalidated by a combination of the minimum MCS index and allocating more PRBs than a predefined or pre-set minimum allocable unit, and / or by a combination of the maximum MCS index and allocating the PRBs of the predefined or pre-set minimum allocable unit.

[0076] According to one embodiment, one or more of the MCS levels conventionally allocated for the purpose of indicating a non-zero redundancy version are used to signal that a codeword is to be invalidated. For example, in LTE, the MCS levels used to indicate a non-zero redundancy version are I MCS = 29, 30, 31.

[0077] However, it should be noted that the present disclosure is not limited to the LTE / LTE-A system or its future evolved forms. In this embodiment, generally, by reusing a field for signaling the modulation and coding scheme that has several values used for purposes other than indicating the modulation and coding scheme, and reinterpreting those values for another purpose, the invalidation of codewords is signaled.

[0078] Exemplary control information in this embodiment includes a resource grant for a plurality of subframes and a plurality of codewords in each subframe, and a modulation and coding scheme (MCS) indicator that is common to the plurality of granted subframes and is individual for each of the plurality of codewords. The MCS indicator can take one of a plurality of values including a value indicating one of the plurality of MCSs and at least one value not indicating an MCS. The MCS indicator for at least one of the plurality of codewords having a value not indicating an MCS signals the invalidation of the codeword.

[0079] For example, the control information in the case of two transmission layers includes two MCS fields (MCS1, MCS2) for two respective codewords. The MCS table can be maintained the same as the current LTE standard specification (see FIG. 5), and the control information can correspond to dedicated control information (DCI) having a format (such as DCI format 4B described above) used for a multi-subframe grant. When one of the codewords is invalidated in all the granted subframes, the corresponding MCS field is set to a value among the redundancy version values 29, 30, 31. For example, when the MCS1 indicator has a value in the range of 0 to 28 and the MCS2 indicator has a value in the range of 29 to 31, the first codeword CW0 is transmitted and the second codeword CW1 is invalidated. On the contrary, when the MCS1 indicator has a value in the range of 29 to 31 while the MCS2 indicator has a value in the range of 0 to 28, the first codeword CW0 is invalidated and the second codeword CW1 is transmitted.

[0080] However, other configurations are possible. For example, among the MCS indicators that do not indicate MCS, there may be one specific value that invalidates the codeword. For example, only the value 31 in the above example can be used to invalidate the corresponding first codeword or second codeword. The remaining values such as 29 and 30 can be used for other purposes (such as signaling of redundant versions or signaling of any other parameters). It is advantageous to choose the value 29 (i.e., the value associated with the redundant version (RV1) that is least frequently used in retransmission), because the remaining values 30 and 31 can still be used to indicate redundant version 2 and redundant version 3, respectively, as originally intended in the communication system.

[0081] As one of the advantages of the signaling described above, single-layer beamforming is supported in multi-subframe grants. Also, by reusing only some of the signaling points of the MCS, which is part of the control information, no extra signaling bits are required to invalidate the codeword. This provides an efficient way to invalidate the codeword while still allowing the most important link adaptation to remain possible.

[0082] However, the present disclosure is not limited by the above example where the invalidation of the codeword is indicated only by a specific value of the MCS indicator. For example, for the purpose of supporting subframe-based invalidation of the codeword, in addition to the MCS level, a redundant version (RV) field that varies for each subframe can be used. The redundant version field can be included in the control information, for example, as shown in FIG. 6 described above. In this case, the redundant version field in DCI format 4B is common to both codewords but is separate (individual) for each subframe and has a length of 1 bit.

[0083] In particular, the value of a specific MCS indicator (field) and the value of the RV field specific to a subframe can cooperate together to indicate the codeword to be enabled / disabled and the redundancy version to be applied.

[0084] For example, if MCS1 has a value within the range of 0 to 28 and MCS2 has a value of 29, and if the first RV state (out of two states distinguishable by 1 bit (e.g., bit value 0)) is indicated, then codeword 1 is disabled. Codeword 0 adopts MCS1 and RV2, that is, the retransmission is executed assuming that the previous transmission was made using RV0. On the other hand, if the second RV (e.g., bit value 1) state is indicated, then codeword 1 is not disabled. Both codeword CW0 and codeword CW1 are transmitted using MCS1 and RV2, that is, the retransmission is executed assuming that the previous transmission adopted RV0.

[0085] When MCS1 has a value within the range of 0 to 28 and MCS2 has a value of 30, if the first RV state is indicated, then codeword 0 is disabled. Codeword 1 (CW1) uses MCS1 and RV0 (either as the first transmission or retransmission depending on the value of the new data indicator (NDI)). On the other hand, if the second RV state is indicated, then codeword 1 is disabled while codeword 0 uses MCS1 and RV0 (similarly, either as a retransmission or a new data transmission depending on the NDI value).

[0086] Furthermore, when MCS1 has a value within the range of 0 to 28 and MCS2 has a value of 31, if the first RV state is indicated, then codeword 0 is disabled and codeword 1 adopts MCS1 and RV2, that is, the retransmission is executed assuming that the previous transmission adopted a redundancy version (RV0) equal to 0. On the other hand, if the second RV state is indicated, then codeword 1 is disabled while codeword 0 uses MCS1 and RV2.

[0087] Note that it should be noted that the above examples do not limit the present disclosure. The above examples only explain how to signal the invalidation or validation of codewords on a subframe-by-subframe basis by interpreting the combination of the value of the MCS indicator and the value of the redundant version field without including additional fields in the control information. Generally, in the case of two codewords, one of the MCS indicators (out of the two MCS indicators corresponding to each of the two codewords) indicates the MCS of the codeword to be validated. The other MCS indicator takes a value that does not indicate the MCS, but together with the value of the redundant version field, indicates which of the two codewords is to be invalidated, or that neither codeword is to be invalidated, and which redundant version is applicable to the codeword to be validated.

[0088] Further embodiments are possible where MCS1 takes values from 29 to 31 and MCS2 takes values from 0 to 28. For example, it can be signaled by such a combination that a further different value of the redundant version is applicable.

[0089] In the above example, as one of the advantages, the MCS table currently defined in LTE can be reused. Therefore, the MCS indicator maintains a length of 5 bits representing 32 possible MCS values. In a legacy uplink grant, these values are used to indicate MCS (values 0 to 28) and redundant versions other than 0 (values 29 to 31). In an uplink multi-subframe grant, these values can be used to indicate MCS (values 0 to 28) and activation / deactivation of codewords (values 29 to 31). However, it should be noted that these do not limit the present disclosure. Generally, there may be three or more layers and thus three or more codewords. Therefore, the MCS can indicate, in all subframes or for each subframe, which codewords are deactivated (optionally, using combinations of some MCS indicator values and RV field values as shown above for two codewords).

[0090] Furthermore, in the above example, for the purpose of signaling the MCS, the legacy MCS table is reused by adopting all the values (0 to 28) indicating the MCS. Only the special values 29 to 31 used to signal redundant versions other than 0 in the legacy system are reinterpreted for the purpose of indicating deactivation of codewords. However, the present disclosure is not limited by such mapping of MCS values. For example, some additional values of the MCS indicator can be used to indicate activation / deactivation of codewords.

[0091] Note that this embodiment (in which one or more MCS field levels not indicating MCS are used to signal that a codeword is invalidated) is generally not limited to multiple subframe allocations. For example, in LAA using single subframe allocation (DCI format 4A), this embodiment (and any of the above-described examples thereof, except for solutions at the subframe level not applicable to single subframe grants) can be adopted. In this embodiment, it is advantageous for the control information to also include precoding indication information common to a plurality of subframes (to which the grant conveyed by the control information is applied). This precoding indication information can be a field within the control information corresponding to the field of legacy DCI format 4.

[0092] [Determination of TPMI] In multi-subframe scheduling that supports multi-layer transmission, it is advantageous to include a precoding information field as described above. In single subframe scheduling, the precoding information is currently signaled in a precoding information field indicating the transmission precoding matrix index (TPMI) together with the number of transmission layers.

[0093] The precoding information field in DCI format 4 for use in the case of two antenna ports has 3 bits and can signal eight combinations of TPMI and the number of layers, which are assigned eight different values. The precoding information field in DCI format 4 used in the case of four antenna ports has 6 bits, and thus the combination of TPMI and the number of layers can take 64 different values. This is currently defined in Table 5.3.3.1.8-1 of Non-Patent Document 4 (which is freely available on the 3GPP website and is incorporated herein by reference).

[0094] FIG. 7 shows the values of the precoding information fields and their corresponding meanings for the case of two antenna ports (FIG. 7A) and the case of four antenna ports (FIG. 7B). These tables respectively correspond to Table 5.3.3.1.8-2 and Table 5.3.3.1.8-3 in Non-Patent Document 4. Specifically, FIG. 7A shows two tables (one with the first two columns and the other with the next two columns), and these two tables target one activated codeword and two activated codewords, respectively. The first and third columns show the values of the bit fields of the precoding information included in the DCI. The second and fourth columns specify the corresponding relevant combinations of the number of layers and the TPMI. When one codeword is activated, six different values of the TPMI corresponding to the indices 0 to 5 of the precoding information field can be selected. Indices 6 and 7 are reserved. When both codewords are activated, currently only one TPMI corresponding to index 0 is supported, while indices 1 to 7 are reserved.

[0095] In FIG. 7B, when one codeword is activated, entries 0 to 39 indicate the combination of the number of layers (which can be 1 or 2) and the TPMI (which can take values 0 to 23). The values 40 to 63 of the precoding information field are reserved. In contrast, when both codewords are activated, the values 0 to 28 of the precoding information field indicate the combination of the number of layers (which can take values 2 to 4) and the TPMI (which can take values 0 to 15). Values 29 to 63 are reserved.

[0096] The TPMI for the case of two antenna ports indicates which codebook index in Table 5.3.3A.2-1 of Non-Patent Document 1 is used, and the TPMI for the case of four antenna ports indicates which codebook index in Tables 5.3.3A.2-2, 5.3.3A.2-3, 5.3.3A.2-4, and 5.3.3A.2-5 of Non-Patent Document 1 is used. The codebook index is associated with a specific precoding matrix.

[0097] For the purpose of maintaining the new DCI (4B) similar to the legacy DCI(4) while keeping the overhead cost of signaling information as small as possible, it is advantageous to keep the same length of the precoding information field. This is particularly advantageous when the channel conditions are not expected to change or when information regarding the changing channel conditions is not available. On the other hand, in order to control the transmission parameters more finely, it may be advantageous to provide the number of layers and the TPMI for each individual subframe, which is particularly advantageous when various channel conditions can be predicted over the entire scheduling period.

[0098] As described above, it is possible to activate / deactivate one codeword per subframe. Therefore, it is desirable to signal precoding information for at least two different cases (one codeword is activated or both codewords are activated).

[0099] According to the first example, a second precoding information field can be provided, which indicates the number of layers and the TPMI of a subframe in which only one codeword is activated (here, it is assumed that the first precoding information field when both codewords are activated is also included in the DCI). The second field can indicate the number of layers and the TPMI in the same way as shown in FIG. 7. In other words, the DCI including the multi-subframe grant can indicate, on a subframe-by-subframe basis, whether one codeword is activated or two codewords are activated. Therefore, two precoding information fields can be provided, namely, the first precoding information field indicating the number of layers and the TPMI when both codewords are activated, and the second precoding information field indicating the number of layers and the TPMI when only one codeword is activated. These two precoding information fields can be defined in the same way as shown in FIG. 7.

[0100] However, instead of this, for the purpose of reducing the requirements for signaling data, a limited number of bits can be used to dynamically select among a pre-set combination. Here, the term "limited" means that the number of combinations is smaller than the number of combinations defined for precoding information in the case of scheduling by DCI format 4 (e.g., in a license carrier).

[0101] Referring exemplarily to the left part of the table in FIG. 7B, the number of selectable TPMIs for each number of transmission layers is sub-sampled so that the total number of options decreases. For example, instead of making all of the TPMI values 0 to 23 selectable for 1-layer transmission, only even TPMI values 0, 2, 4, ..., 22 are available (alternatively, only odd TPMI values 1, 3, 5, ..., 23 are available). Similarly, for 2-layer transmission, only even TPMI values 0, 2, 4, ..., 14 are available (alternatively, only odd TPMI values 1, 3, 5, ..., 15 are available). In this way, a total of 20 values are available, and (instead of 6 bits for selecting all 40 values) the 20 values can be signaled by a 5-bit field.

[0102] Subsampling does not have to be in a regular pattern (every other value, every second value, etc.) because in a regular pattern, generally the capacity of the bitfield signal is not fully utilized. That is, as explained now, for subsampling by a factor of 2, a 5-bit field size is required, but in this subsampling, only 20 out of the 32 possible states are utilized. Utilizing all 32 states can be achieved, for example, by selecting 16 out of the 24 defined TPMI values for single-layer transmission and maintaining the 16 TPMI values as they are for two-layer transmission. Such non-uniform subsampling is advantageous for supporting more optimized two-layer transmission. An alternative method is to maintain the 24 TPMI values as they are for single-layer transmission and select 8 out of the 16 defined TPMI values for two-layer transmission. The latter can be easily achieved by subsampling the 16 values by a factor of 2 (e.g., selecting only even TPMI or only odd TPMI). In such a method, all the TPMI options for single-layer transmission are ensured, which is advantageous for achieving optimal SINR in the extended coverage of the uplink signal. Similarly, if only, for example, 3 bits should be used in the second precoding information field, it is necessary to subsample the total of 40 different combinations of the number of layers and TPMI down to 8 combinations. This can be achieved by subsampling the 24 TPMI defined for single layer by a factor of 3 and not including any TPMI for two layers.

[0103] As a further advantage of including a second precoding information field applicable to a subframe in which one codeword is activated and one codeword is deactivated, the size of the first precoding information field can be reduced. Since the first precoding information field only needs to cover the case where two codewords are activated, for four antenna ports, it only needs to represent states 0 to 28. These 29 states can be represented by 5 bits, and thus, compared to the size of the precoding information field in DCI format 4 for four antenna ports, 1 bit can be saved. For two antenna ports, including the first precoding information field in the DCI is even unnecessary. In other words, the size of this field can be 0 bits, because only combinations of two layers and TPMI are defined.

[0104] This method can also be extended when more than three codewords are supported per subframe. In that case, a first precoding information field applicable to a subframe in which no codeword is deactivated is provided, a second precoding information field applicable to a subframe in which a first non-zero number of codewords are deactivated is provided, a third precoding information field applicable to a subframe in which a second non-zero number of codewords are deactivated is provided, and so on. In other words, the number of precoding information fields is generally capped by the maximum number of codewords that can be activated in a subframe, and preferably, it matches the maximum number of codewords that can be activated in a subframe.

[0105] According to the second example, the precoding information for the case of one codeword is set semi-statically (e.g., by the Radio Resource Control protocol (RRC)). In other words, the precoding information for the case of both codewords (see the right sides of FIGS. 7A and 7B) is included in the DCI that conveys the multi-subframe grant, and the precoding information for the case where only one codeword is activated is signaled by the RRC. The TPMI for the case of two codewords is mainly aimed at minimizing the interference between the two codewords, and the TPMI for the case of one codeword is mainly aimed at improving the SINR through beamforming. The optimal beam direction for beamforming coincides with the line of sight between the transmitter and the receiver in many scenarios, and the line of sight does not change much in the case of a terminal that does not move much. Conversely, the optimal precoder for minimizing inter-symbol interference attempts to eliminate the correlation between channels as much as possible in many scenarios, and this attempt depends greatly on the obstacles in the radio wave propagation environment and can therefore be predicted to be more variable. For these reasons, it is most efficient that the precoding information for one activated codeword follows semi-static RRC signaling, while the precoding information for two activated codewords is preferably indicated in the DCI (and thus can be adapted relatively quickly to changing channel conditions).

[0106] Alternatively, the precoding information for two activated codewords can be set by semi-static signaling, and the precoding information for one activated codeword is included in the DCI format. This method is particularly applicable when the number of layers and the number of available options of TPMI are considerably larger in the case of one codeword than in the case of two codewords. For example, referring to FIG. 7A, in the case of two codewords, there is only one valid entry. From this perspective, it is even possible to operate without the corresponding precoding information field in the DCI. Conversely, in the case of one codeword, there are six different entries as options, and thus it can be predicted that even if the channel conditions change slightly, the optimal selection of TPMI may be different.

[0107] The semi-static signaling can be conveyed by a terminal-specific RRC message when establishing a radio access bearer or at any timing of reconfiguring the radio access bearer thereafter.

[0108] This example and alternative can also be extended to the case of three or more codewords per subframe, in which case the precoding information for the first number of deactivated codewords and the second number of deactivated codewords is conveyed by semi-static settings respectively, and the precoding information for the third number of deactivated codewords is conveyed by DCI. Alternatively, the precoding information for the first number of deactivated codewords and the second number of deactivated codewords is conveyed by DCI respectively, and the precoding information for the third number of deactivated codewords is conveyed by semi-static settings.

[0109] According to the third example, the candidates for the precoding information in the case of one codeword are set semi-statically. Further, a specific selection of the precoding information among the candidates set semi-statically in advance is signaled dynamically, for example, by using some values of MCS and / or RV. For example, to indicate the selection of the first candidate, the second candidate, and the third candidate, MCS value 29, MCS value 30, and MCS value 31 can be used respectively. The first candidate, the second candidate, and the third candidate can be set by the RRC by assigning specific combinations, such as the combinations defined in the table of FIG. 7, to these candidates.

[0110] In another example specific to the third example, MCS value 29, MCS value 30, and MCS value 31 can be used together with the first RV value to indicate the selection of the first candidate, the second candidate, and the third candidate respectively, while MCS value 29, MCS value 30, and MCS value 31 can be used together with the second RV value to indicate the selection of the fourth candidate, the fifth candidate, and the sixth candidate respectively. The first to sixth candidates can be set by the RRC by assigning specific combinations, such as the combinations defined in the table of FIG. 7, to these candidates.

[0111] This third example can be extended when three or more codewords are supported and at least one codeword is invalidated. The number (and index) of the invalidated codewords can be determined from the recognition of whether the corresponding MCS field contains values from 0 to 28 (i.e., assigns a modulation and coding scheme) or values from 29 to 31. This extends additional dimensions with respect to the number of layers and the number of semi-statically pre-set candidates for precoding. For example, when three codewords and the corresponding three MCS fields are supported, when one codeword is enabled and when two codewords are invalidated, it is characterized by a first MCS field taking values from 0 to 28 and a second MCS field and a third MCS field each taking values from 29 to 31. Therefore, two MCS fields each indicating 29 to 31 together provide nine different options, and these options can be used to represent nine different combinations of the number of transmission layers and TPMI. In addition to this, by using the RV field, the number of configurable combinations can be further increased.

[0112] According to the fourth example, to signal the precoding information for both two activated codewords and one activated codeword, only one precoding information field is included in the DCI. This precoding information field is similar to the precoding information field used in DCI format 4 for the case of two codewords in a legacy system, i.e., for four antenna ports, it has 6 bits and 29 possible values, and the remaining values are reserved. Values 0 to 28 represent the index of the combination of the number of layers and the TPMI value. Values 29 to 63 are reserved. In this example, the reserved values are used to convey individual candidates for only one activated codeword. Thus, for the two-codeword transmission with both activated codewords, values 0 to 28 indicate the same combination of TPMI and the number of layers as used by DCI format 4. When only one codeword is activated, values 29 to 56 indicate the combination (TPMI and the number of layers) for the one activated codeword. The combinations associated with values 0 to 28 can be the same as the respective combinations associated with values 29 to 56. The remaining values 57 to 63 can be used for other purposes. Alternatively, the remaining values can be used to provide more selectable combinations.

[0113] In the following, the value indicated by the precoding information field is represented as I L,TPMI and a specific example for determining the number of layers and the TPMI according to this fourth example is presented. For four antenna ports, for two activated codewords, the number of layers and the TPMI are obtained by using "I L,TPMI mod 29" to search in the "bit field mapped to the index" column according to the table in Figure 7B. Thus, I L,TPMI = 0 and I L,TPMI = 29 both indicate that 2 layers and TPMI = 0 are used in the assigned transmission. Similarly, I L,TPMI = 17 and I L,TPMI= 46 both indicate that 3 layers and TPMI = 1 are used in the assigned transmission. In the case of a subframe where one codeword is activated and one codeword is deactivated, I L,TPMI = {0 - 28} indicates that the first combination of TPMI and the number of layers is used in the assigned transmission, while I L,TPMI = {29 - 56} indicates that the second combination of TPMI and the number of layers is used in the assigned transmission. The first combination and the second combination (and other combinations if applicable) are preferably selected from a series of combinations available for one deactivated codeword in the case of single subframe scheduling, for example, selected from the series of combinations in the left part of the table in Figure 7B ("Message"). This selection is preferably pre - defined through a determined specification or can be set by semi - static signaling so that the combination that is optimal for specific channel conditions can be selected for each terminal and in a timely manner.

[0114] In a specific example for two antenna ports, for two activated codewords, the number of layers and TPMI are obtained using "I L,TPMI mod 1" to search in the "Bit field mapped to index" column in the table of Figure 7A. Thus, I L,TPMI = {0, 1, 2, 3, 4, 5, 6, 7} all indicate that 2 layers and TPMI = 0 are used in the assigned transmission (this is clearly self - evident as this is a special case where only one type of number of layers and TPMI is defined). In the case of a subframe where one codeword is activated and one codeword is deactivated, I L,TPMI = {0} indicates that the first combination of TPMI and the number of layers is used in the assigned transmission, while I L,TPMI{2} indicates that in the assigned transmission, a second combination of TPMI and the number of layers is used, and the same applies hereinafter. The first combination, the second combination, and another combination (if applicable) are preferably selected from a series of combinations available for one invalidated codeword in the case of single subframe scheduling, for example, selected from the series of combinations in the left part (``Message'') of the table in FIG. 7A. This selection is preferably predefined through a defined specification, or can be set by semi-static signaling so that a combination that is optimal for specific channel conditions can be selected for each terminal and in a timely manner. In this specific example, a total of six combinations are defined for one activated codeword, and the precoding information field can represent more than six (eight in this specific example) combinations, and thus it is possible to indicate all six defined combinations without the need to be set semi-statically.

[0115] According to a fifth example, the DCI for transmitting the multi-subframe allocation does not include a second precoding information field. When two codewords are activated in a subframe, the number of layers and the precoding information are determined according to the precoding information field included in the DCI format 4B (for multi-subframe allocation). When one codeword is activated in a subframe, the number of layers and the precoding information are determined from the precoding information in the most recently signaled DCI format 4A (for single subframe allocation). In this example, it is assumed that the channel conditions, and thus the appropriate combination of TPMI and the number of layers, do not change substantially over time (this is assumed without problem for at least relatively stationary terminals).

[0116] According to the sixth example, a certain mapping is introduced between the combination of precoding information signaled for both activated codewords and the applicable combinations for one activated codeword. In other words, the multi-subframe DCI (format 4B) includes one precoding information field, similar to DCI format 4. This precoding indication information signals the combination of TPMI and the number of layers for two activated codewords. Therefore, the subframe in which both codewords are activated utilizes this signaled combination. The subframe in which only one of the two codewords is activated applies the combination obtained according to a certain mapping of the combination signaled for both activated codewords to the applicable combinations for one activated codeword.

[0117] In the examples so far, codewords can be invalidated or validated on a subframe-by-subframe basis. Furthermore, precoding information is signaled individually for different numbers of validated codewords, which is advantageous. The examples so far have been presented in the context of an existing LTE system. However, it should be noted that the present disclosure is not limited to LTE, or at most two codewords, or precoding information signaled as shown in FIG. 7. Instead, the present invention is applicable to any system using multi-subframe allocation with MIMO by precoding that enables mapping of two or more codewords to one subframe. In such a system, one or more codewords can be invalidated on a subframe-by-subframe basis by using the value of a modulation and coding scheme indicator not associated with a specific MCS, in combination with a specific value of another signaled parameter such as a redundant version in some cases. Correspondingly, precoding information can be signaled for each such setting (one codeword is invalidated, two codewords are invalidated, three codewords are invalidated, etc.). Such signaling can be provided, for example, by explicitly including a precoding information field for each setting in the DCI according to the examples described above, or by semi-statically setting the precoding information for each such setting, or by a combination of including in the DCI and semi-static signaling, or by reusing a reserved field.

[0118] Instead, information on whether one codeword is invalidated or two codewords are validated is conveyed by the precoding information field. This alternative method is applicable not only to single subframe scheduling but also to multi-subframe scheduling, where the activation or deactivation of codewords is applied to all subframes scheduled by the corresponding DCI. The first set of precoding information values implicitly indicates that one codeword is invalidated, and the second set of precoding information values implicitly indicates that two codewords are validated. For example, in the case of two antenna ports, referring to FIG. 7A, the first set consists of the six values shown in the two left columns and the corresponding interpretations, and the second set consists of one value in the two right columns and the corresponding interpretation. Thus, there are a total of seven values, i.e., the 3-bit size of the precoding information field can be maintained. When the value indicated by the precoding information field is denoted as I L,TPMI the following method can be used. · When 0 ≤ I L,TPMI ≤ 5: Codeword 0 is validated and codeword 1 is invalidated. Determine the number of layers and the TPMI according to I L,TPMI in the two left columns. · When I L,TPMI = 6: Codeword 0 is validated and codeword 1 is validated. Determine the number of layers and the TPMI according to I L,TPMI - 6 in the two right columns.

[0119] For example, in the case of four antenna ports, referring to FIG. 7B, the first set consists of the 40 values shown in the two left columns and the corresponding interpretations, and the second set consists of the 29 values in the two right columns and the corresponding interpretations. Thus, there are a total of 69 values, i.e., the size of the precoding information field is 7 bits. When the value indicated by the precoding information field is denoted as I L,TPMIWhen expressed as, the following method can be used. · When 0 ≦ I L,TPMI ≦ 39: Codeword 0 is enabled and Codeword 1 is disabled. The number of layers and TPMI are determined according to I in the left two columns. L,TPMI as follows. · When 40 ≦ I L,TPMI ≦ 68: Codeword 0 is enabled and Codeword 1 is enabled. The number of layers and TPMI are determined according to I - 40 in the right two columns. L,TPMI as follows.

[0120] In this way, the set can be reduced (subsampled) so as to achieve a smaller number of bits in the precoding information field. For example, considering the case of four antenna ports, for the sake of commonality in the system, it may be desirable to maintain the number of 6 bits in the precoding information field. With 6 bits, a set size of 64 combinations is supported, that is, compared with the complete set of combinations, it is necessary to delete 69 - 64 = 5 combinations. Such subsampling can be applied, for example, as described above in relation to the first example.

[0121] Furthermore, the present disclosure provides an apparatus 810 that receives resource grants for a plurality of subframes in a communication system 800. Such an apparatus can be any type of mobile station (user equipment: UE) such as a mobile phone, smartphone, USB adapter, computer, tablet, laptop computer, wearable device (such as a smartwatch or smart glasses), etc. The communication system is advantageously an LTE system or an LTE-A system. However, the present invention is not limited to the LTE system. Instead, any 4G system or 5G system, and further, any system such as WiFi, WiMax that employs a plurality of antennas and corresponding signaling can be utilized.

[0122] The apparatus includes a transceiver 820 that receives a signal 855 including control information. The transceiver can be, for example, a transceiver capable of receiving and transmitting LTE / LTE-A compatible signals. FIG. 9 illustrates possible uplink transmission processing (FIG. 9A) and possible downlink transmission processing (FIG. 9B) in LTE. However, it should be noted that these are merely examples. The transceiver 820 generally includes one or more antennas, corresponding circuits for controlling the gain of the antennas, and a mapper for user data, control data, and reference signals to physical resources.

[0123] The control information included in the signal 855 includes resource grants for a plurality of subframes and a plurality of codewords in each subframe. The resource allocation can indicate the position of transmission resources in the time domain and / or frequency domain. The number of subframes for which the resource allocation is valid can also be signaled in the control information as illustrated in FIG. 6. However, it should be noted that the present disclosure is not limited thereby, and the number of subframes may be preset (e.g., semi-statically) or defined in another way in advance. The plurality of codewords are two or more codewords, and some of them can be invalidated.

[0124] The control information is common to a plurality of allocated subframes and further includes a modulation and coding scheme (MCS) indicator for each of the plurality of codewords. The MCS indicator takes one of a plurality of values including a value indicating one of the plurality of MCSs and at least one value not indicating an MCS. The MCS indicator can be a field having a predefined bit length capable of representing a series of values. Some of the values are associated with a particular modulation (more specifically, the modulation order when the modulation type is the same) and the size of the (one or more) transport blocks mapped to the allocated resources (determined by the applied coding). Some of the values are not associated with coding or modulation. The latter values can be used or reserved for another purpose. In the above UL LTE example, values 29 to 31 are used to signal the redundancy version.

[0125] When the control information is received by the transceiver 82 as part of the signal 855, the processing device 830, which is part of the apparatus 810, further processes the control information. In particular, the processor 830 is configured to determine that the codewords from the plurality of codewords in the plurality of subframes are invalidated when the MCS indicator for at least one of the plurality of codewords has a value not indicating an MCS, and not invalidated otherwise. This does not necessarily mean that an MCS indicator not indicating an MCS always means invalidation. In one embodiment, an MCS indicator not indicating an MCS always means invalidation. In another embodiment, an MCS indicator not indicating an MCS can indicate invalidation only in combination with another parameter value, as shown later.

[0126] The processing device 830 can be one processor or multiple processors. The processing device 830 can be an integrated circuit, or programmable hardware, or a combination of such devices. Such a processing device 830 can extract control information from the signals received by the transceiver 820, and further extract a specific field of the control information that conveys the set value. As described above, the signal 855 can correspond to a downlink signal transmitted from the eNB to the terminal in the current LTE system or LTE-A system, the control information can correspond to DCI, the MCS indicator can correspond to the MCS field, and the precoding information can correspond to the combination of the TPMI and the number of layers.

[0127] In one embodiment, the above plurality of values include 32 indexed values according to the PUSCH MCS table applied in LTE. Among these values, the three values with the largest index do not indicate the MCS and can be used to indicate the invalidation of the codewords of multiple subframes. In particular, the 32 values can be given by all combinations of 5 bits such that the MCS indicator is 5 bits long (i.e., a 5-bit field is included in the DCI). Further, among the 32 values, a predefined or preset number of values can be associated with each specific MCS (29 in LTE, i.e., values 0 to 28), while the remaining values are not associated with a specific MCS (3 in LTE, i.e., 29 to 31). The value 32 is advantageous because it enables the reuse of the MCS table already defined in LTE. However, the present invention is not limited by this example, and the number of values can be larger or smaller depending on the number of bits provided for signaling the MCS in the control information. As an advantage of this method in the LTE example, instead of further reducing the number of configurable MCSs, values indicating redundant versions are utilized. When the RV is signaled individually for each subframe as illustrated in FIG. 6, the RV value is no longer necessary.

[0128] In other words, a legacy terminal can use the MCS table to indicate MCS and / or RV, while a terminal configured to support multi-subframe allocation can use (interpret) the same MCS table to indicate MCS in the same way as a legacy terminal and to indicate the deactivation of codewords.

[0129] Advantageously, the control information further comprises redundant version indication information that is individual for each of a plurality of subframes and common to all codewords in each subframe. In this case, the processing device is configured to determine that codewords from a plurality of codewords in a plurality of subframes are deactivated when an MCS indicator for at least one of the plurality of codewords has a value that does not indicate an MCS and the redundant version indication information has a first predefined value. Otherwise, i.e., when the MCS indicator takes a value indicating a particular MCS among a plurality of configurable MCSs and is combined with another value of the redundant version indication information indicating one of the configurable redundant versions signaled per subframe, the codeword or codewords are not deactivated. As will be apparent to those skilled in the art, in the above example specific to LTE, the length of the redundant version indicator for a subframe in multi-subframe DCI was 1 bit (indicating a choice between the two most performance-critical RVs, RV = 0 and RV = 2), but this does not limit the present disclosure. The redundant version may be 2 bits long, indicating RVs from 0 to 3, as in legacy DCI, or any other length in cases where a system requires more redundant versions.

[0130] As described above, in a subframe where one codeword is activated and one codeword is deactivated, it is advantageous for the processing device to be configured to determine the redundant version of the activated codeword based on a specific value that does not indicate the MCS (used together with the redundant version indication information to indicate the deactivation of the deactivated codeword). In other words, the MCS indicator and the RV indicator (both included in the control information) cooperate to indicate the deactivation or activation of the codeword and the RV of that codeword.

[0131] In a subframe where two codewords are activated and neither codeword is deactivated, the processing device can be configured to determine the MCS of the activated codeword based on a specific value that indicates the MCS, such as values 0 to 28 in the above example related to LTE. Such a value is not used to indicate the deactivation of the deactivated codeword (optionally together with the redundant version indication information).

[0132] The control information can further include a precoding information field that is common to a plurality of subframes for which the control information indicates an allocation (grant). The precoding indication information field can indicate the TPMI and / or the number of layers. Note that in the above example, the precoding information field indicates the combination of this TPMI and the number of layers because there is a similar precoding information field in current LTE. However, it should be noted that the present disclosure is not limited by these examples. Instead, the precoding information field may indicate only the TPMI, and the number of layers may generally be signaled by another field, or implicitly indicated, or signaled in another layer. On the other hand, the precoding information may signal further settings.

[0133] In one embodiment, the precoding information indicates a combination of transmission precoding matrix indication information (TPMI) and the number of transmission layers. This can be performed in various different ways.

[0134] For example, in one example, the precoding information can indicate one combination of TPMI and the number of transmission layers out of a plurality of predefined combinations of TPMI and the number of transmission layers. These combinations can be predefined in a standard specification and can be known to both the receiver and the transmitter.

[0135] In another example, the precoding information can indicate one combination of TPMI and the number of transmission layers out of a plurality of combinations of TPMI and the number of transmission layers in a set of candidates preconfigured by semi-static signaling. In particular, an RRC message from the base station to the terminal can set a set of candidate indexes associated with each combination of TPMI and the number of layers. It is advantageous that the number of combinations in the set of candidates is smaller than all possible combinations and / or all configurable settings. The set of candidates can be selected based on, for example, channel conditions, interference, terminal capabilities, or any other parameter. In this case, the control information conveys a precoding information field with a smaller bit length that enables signaling of only the values within the preconfigured set of candidates. For example, if there are generally 32 possible combinations, 5 bits are required for the precoding information to signal them. However, the set of candidates can include only 4 candidate combinations preconfigured by RRC, in which case only 2 bits are required to select a combination among the candidates in the dynamically signaled precoding information.

[0136] In yet another example, the pre-coding information can be selected from among a plurality of predefined combinations of TPMI and the number of transmission layers even in the case of a single-layer setting using one codeword per sub-frame, or, in the case of a single-layer setting, can be a single combination of TPMI and the number of transmission layers that is not selectable, where the value of the pre-coding indication information indicating each combination of TPMI and the number of transmission layers that is not selectable in the case of a single-layer system is a reserved value in the pre-coding indication information for the single-layer setting.

[0137] In other words, the transceiver is configured to receive the setting information of the radio resource control protocol including the pre-coding setting, and the processing device is further configured to set the pre-coding parameters according to the received pre-coding setting.

[0138] FIG. 8 also shows an apparatus 850 that transmits resource grants for a plurality of sub-frames in a communication system. This apparatus can be a network node or a base station, or a terminal that operates as an access point, or any other scheduling entity. In LTE, this apparatus can correspond to an eNB.

[0139] The apparatus 850 includes a processing device 870 configured to set a modulation and coding scheme (MCS) indicator to a value that does not indicate an MCS in order to indicate that codewords from a plurality of codewords in a plurality of sub-frames are invalidated. For example, this apparatus can be a scheduling entity that selects a transmission setting for another apparatus and provides the selected setting to that other apparatus via control information. This setting can include, for example, physical layer parameters such as modulation and coding settings, MIMO settings such as the number of layers and pre-coding matrices, resource allocation, HARQ settings, and the like.

[0140] The apparatus 850 further includes a transceiver 860 that transmits a signal including control information, where the control information includes at least a resource grant for a plurality of subframes and a plurality of codewords in each subframe, precoding indication information common to the plurality of subframes, and an MCS indicator that is common to the plurality of granted subframes and is individual to each of the plurality of codewords (taking one of a plurality of values including a value indicating one of a plurality of MCSs and at least one value not indicating an MCS).

[0141] The processing device 870 can be one or more processors, and / or one or more integrated circuits, and / or programmable hardware, etc., configured or programmed to perform the tasks described above, similar to the processing device 830. It should be noted that it is further advantageous for the processing device 870 to select the control information and the values of its respective fields as described above in relation to the apparatus 810 and the extraction / processing of the control information by the apparatus 810.

[0142] Furthermore, as shown in FIG. 8, a communication system is also provided, which includes an apparatus 810 that receives control information and an apparatus 850 that transmits control information for controlling the transmission of data through a channel by the apparatus 810. The channel may be at least partially a wireless channel. The system can be part of a communication system, and the communication system can be, for example, LTE, LTE-A, a further evolved form of LTE (such as LAA), or any other system including a wireless link.

[0143] [Invalidation by Dedicated Field] According to one embodiment, the activation / deactivation of codewords is explicitly indicated and is valid for each subframe of the corresponding resource allocation. The control information can include, in particular, a dedicated codeword activation / deactivation field indicating the activation and / or deactivation of the codewords for each subframe allocated by the resource allocation. The dedicated codeword activation / deactivation field preferably consists of one bit in the control information, with the first bit state (e.g., bit value = 0) indicating that one codeword is activated and one codeword is deactivated, and the second state (e.g., bit value = 1) indicating that two codewords are activated. This activation / deactivation is applied in each subframe allocated by the control information, and thus this embodiment is applicable not only to single subframe allocation but also to multi-subframe allocation. In other words, by including a corresponding activation / deactivation field common to all subframes in the multi-subframe DCI, the activation / deactivation of the codewords is explicitly indicated in the multi-subframe DCI.

[0144] According to another embodiment, the activation / deactivation of codewords is explicitly and individually indicated for each subframe. In particular, the control information can include a dedicated codeword activation / deactivation field indicating the activation and / or deactivation of the codewords for each subframe.

[0145] In one example, a codeword activation / deactivation bitmap is provided, in which each bit represents a subframe and the value of each bit indicates whether the codeword is activated or deactivated in the corresponding subframe. This designation can be done by one bit, with the bit set to 0 indicating that one codeword is deactivated and set to 1 indicating that both codewords are activated (or vice versa if only two configurable codewords exist).

[0146] In other words, assuming that the maximum number of codewords is equal to 2, the codeword activation / deactivation field (bitmap) indicates whether each subframe uses one codeword or two codewords. Therefore, the bitmap can have a length of, for example, 2 bits, 3 bits, 4 bits, or 5 bits or more (generally 10 bits or less) according to the set value of the number of subframes to which one scheduling message is provided (the number of subframes in multiple subframes).

[0147] Note that it should be noted that the present disclosure is not limited to the case where only two configurable codewords exist as in the above-described LTE example. Bitmaps for each subframe and codeword can be provided for the purpose of indicating the activation / deactivation of a larger number of codewords. In the case of a larger number of codewords, it is assumed that one MCS field for each codeword is included in the DCI.

[0148] In this embodiment, a modulation and coding scheme indicator taking values from 0 to 28 is advantageously applied to select the modulation and coding scheme in both cases of two-codeword transmission (when both codewords are activated) and one-codeword transmission (when only one codeword is activated). In other words, when two-codeword transmission is indicated by the codeword activation / deactivation field for a subframe, the MCS with index values from 0 to 28 is applied to both codewords in that subframe, and when one-codeword transmission is indicated by the codeword activation / deactivation field for a subframe, the MCS with index values from 0 to 28 is applied to one codeword in that subframe.

[0149] The invalidation of codewords does not necessarily have to be indicated by a bitmap. Instead, a field indicating whether the codewords in each individual subframe are enabled or disabled can indicate the number of codewords to be invalidated and / or identification information. Alternatively, this field can indicate the number of codewords to be enabled and / or identification information.

[0150] For example, for each subframe, the codeword enable / disable field can represent two states, namely, (1) two codewords are enabled, and (2) one codeword is enabled and one codeword is disabled. In such an example, when only one codeword is enabled, it can be assumed that the first codeword is enabled and the second codeword is disabled. Such a field requires a total of exp(2,n) states for n subframes, and these states can be represented by an n-bit long field.

[0151] In another example, for each subframe, the codeword enable / disable field can represent three states, namely, (1) two codewords are enabled, (2) codeword 0 is enabled and codeword 1 is disabled, and (3) codeword 0 is disabled and codeword 1 is enabled. Such a field requires a total of exp(3,n) states for n subframes, and these states can be represented by a field of length Ceil{log2(exp(3,n))} bits.

[0152] In another example, for each subframe, the codeword enabling / disabling field can represent four states, namely, (1) two codewords are enabled, (2) codeword 0 is enabled and codeword 1 is disabled, (3) codeword 0 is disabled and codeword 1 is enabled, (4) codeword 0 is disabled and codeword 1 is disabled. Such a field requires a total of exp(4,n) states for n subframes, and these states can be represented by a 2n-bit long field.

[0153] Regarding the pre-coding information, the options described above can also be applied to this embodiment. In other words, by inserting a pre-coding information field into the control information, the pre-coding information can be indicated within the control information. The pre-coding information field can be inserted separately for the case of setting 1-codeword transmission and the case of setting 2-codeword transmission. For details of such pre-coding information, refer to the section "Determination of TPMI" above.

[0154] However, the pre-coding information can be indicated in another way. For example, one pre-coding information field can be included in the control information, and this pre-coding information field indicates the pre-coding information in the case of a 2-layer setting where both codewords are enabled. In this case, this pre-coding information is applied to the subframe where both codewords are enabled. Furthermore, reserved MCS entries 29 to 31 can be used to obtain the pre-coding setting for the case of 1-codeword transmission, that is, the setting of the subframe where only one of the two codewords is enabled (one codeword is disabled).

[0155] In particular, in the case of transmitting one codeword, when MCS1 is equal to 29 to 31, there is a selection among three possible settings (combinations of TPMI and the number of layers). When MCS2 is equal to 29 to 31, there is a selection among three additional settings. Therefore, the base station can dynamically select among six precoding settings for the case of one codeword. The six possible values can also represent combinations of TPMI and the number of layers as described above. However, the present invention is not limited thereto, and the precoding information may convey only the precoding matrix indication information. The number of layers can be indicated in another way.

[0156] It is advantageous that the assignment of the combination of TPMI and the number of layers to MCS1 and MCS2 is controlled semi-statically. In other words, a set of candidate values signaled by RRC is assigned to the values 29 to 31 of MCS1 and MCS2. In this case, the dynamic signaling in the control information for conveying the grant only selects a combination from the pre-set set of candidates.

[0157] Note that the setting of the precoding information based on the MCS field value that does not indicate MCS as described above is only usable when the activation / deactivation of the codeword for each subframe is explicitly signaled. Otherwise, the MCS field values that are not used for the purpose of signaling MCS (furthermore, in legacy communications such as single-layer communication without MIMO or in single subframe DCI (especially DCI format 4)) can be used to indicate the precoding information regardless of how the activation / deactivation of the codeword is signaled. Note that referring to the MCS table in FIG. 5, it should be noted that the MCS field values 29, 30, and 31 can also be defined as values not used for signaling the transport block index or modulation.

[0158] According to this embodiment, an apparatus 810 that receives resource grants for a plurality of subframes in a communication system includes a transceiver 820 that receives a signal including control information. The control information includes a common resource grant for a plurality of subframes and a plurality of codewords of each subframe, and codeword indication information indicating activation or deactivation of one or more codewords of each of the plurality of subframes. The apparatus 810 further includes a processing device 830 configured to determine, for each subframe, whether a codeword from the plurality of codewords in that subframe is to be activated or deactivated according to the codeword indication information.

[0159] The codeword indication information is, for example, a bitmap including individual bits for each of the plurality of subframes, and each individual bit indicates whether one codeword is to be activated or two codewords are to be activated.

[0160] However, the bitmap is only one example. Instead, the codeword indication information may be either an identifier of the deactivated codeword or an identifier of the activated codeword. In particular, when there are three or more codewords that can be set for transmission, it may be advantageous to include in the codeword indication information also the number of deactivated codewords or the number of activated codewords. In some systems, it may be advantageous to signal only either the number of deactivated codewords or the number of activated codewords, assuming that the deactivated codewords are the codewords with the highest index.

[0161] Furthermore, in this embodiment, the control information is common to a plurality of subframes to be granted and further includes a modulation and coding scheme (MCS) indicator for each of the plurality of codewords, the MCS indicator taking one of a plurality of values including a value indicating one of the plurality of MCSs and at least one value not indicating an MCS, while the processing device is further configured to determine the modulation and coding scheme of each enabled codeword according to an MCS indicator taking a value indicating one of the plurality of MCSs, which is advantageous.

[0162] When one codeword is enabled, the processing device determines a precoding setting based on an MCS indicator taking a value not indicating one of the plurality of MCSs, or determines which codeword is disabled based on an MCS indicator taking a value not indicating one of the plurality of MCSs or based on a redundancy version indicator for a subframe in which one codeword is enabled.

[0163] Also in this embodiment, corresponding to the control information receiving device 810, a device 850 for transmitting resource grants for a plurality of subframes in a communication system is provided.

[0164] The device 850 includes a processing device configured to select, for each subframe, whether a codeword from the plurality of codewords in that subframe is to be enabled or disabled and accordingly set codeword indication information, a common resource grant for the plurality of subframes and the plurality of codewords of each subframe, and codeword indication information indicating the enabling or disabling of one or more codewords of each of the plurality of subframes, and a transceiver for transmitting a signal including the control information.

[0165] A further feature of the control information is the same as the features described above in relation to the corresponding control information receiver. It is advantageous for the control information transmitting device to be a scheduling device such as a base station or a network node (an eNB in LTE has both of these functions). The control information transmitting device generally not only transmits the control information, but also selects the control information parameter values by which the control information receiving device is set thereby.

[0166] FIG. 10 shows an exemplary method according to the present disclosure. Specifically, FIG. 10 shows a method of receiving resource grants for a plurality of subframes in a communication system. Such a method can be executed in a device such as a user equipment (UE) as illustrated in the figure. The method includes a step (1020) of receiving a signal including control information. The control information can be downlink control information (DCI). For the purposes of the present invention, the manner in which the DCI is received is not important. The reception of the DCI can be by means of monitoring a PDCCH (including blind decoding) as in LTE, but can also be performed in a scheduling-based manner or by any other method.

[0167] The DCI includes a resource grant for a plurality of subframes and a plurality of codewords of each subframe, and a modulation and coding scheme (MCS) indicator that is common to the plurality of granted subframes and individual for each of the plurality of codewords. The MCS indicator takes one of a plurality of values including a value indicating one of the plurality of MCSs and at least one value not indicating an MCS. Correspondingly, the method can further include step (1030) of extracting a resource grant (resource allocation (RA)) for a plurality of subframes from the DCI, and step (1040) of extracting an MCS indicator for each of the plurality of codewords. Then, the MCS value for the first codeword is evaluated (1050). If the MCS belongs to a range of values not assigned to any MCS (yes in step 1050), in step 1060, that codeword can be directly set to be invalidated in the scheduled transmission. However, according to another embodiment, in step 1060, one or more additional parameters are checked for the purpose of determining whether that codeword is to be invalidated. The same evaluation is performed for the second (or subsequent) codeword. The check can include an evaluation of the RV value signaled on a subframe-by-subframe basis, thereby making it possible to further control activation / deactivation on a subframe-by-subframe basis. In other words, step 1060 is a step of determining that the plurality of codewords in the plurality of subframes are invalidated when the MCS indicator for at least one of the plurality of codewords has a value not indicating an MCS (yes in step 1050), and not invalidated otherwise (no in step 1050). In step 1070, the scheduled data transmission is performed. Specifically, the transmission over the plurality of subframes is performed in the allocated (granted) resources using the set MCS for the activated codewords.

[0168] The step of evaluating the MCS value and the corresponding one or more other parameters can include steps corresponding to the functions of the processing device described above with respect to the apparatus.

[0169] For example, the method may further include the step of extracting precoding indication information common to a plurality of subframes from DCI. The precoding indication information can also be common to both codewords of all subframes. Specifically, when both codewords are enabled, a precoding indication information field indicating the TPMI and the number of layers for both enabled codewords can be provided, and when only one codeword is enabled, a precoding indication information field indicating the TPMI and the number of layers for the one enabled codeword can be provided. When the codewords are enabled or disabled on a subframe-by-subframe basis, the method may include the step of extracting first precoding indication information for subframes in which both codewords are enabled and second precoding indication information when only one codeword is enabled. These indication information can be extracted from two separate fields in the DCI, and these two fields can have the same length or can be different. These fields can have a format similar to the current precoding information field (signaling a combination of TPMI and the number of layers) in LTE. However, for the purpose of transmitting control information more efficiently, preferably only one precoding information field having a format similar to the precoding information field in the case of a configuration with four antenna ports and both codewords enabled in legacy (single subframe scheduling) may be extracted from the DCI. The precoding indication information for single codeword transmission is obtained according to a first range of values within this field, and the precoding information when both codewords are enabled is obtained according to a second range of values (independent of the first range of values) within this field. Further alternative methods for determining precoding indication information for a subframe in the case of one or both codewords are described above in relation to the signal structure and the corresponding apparatus.

[0170] FIG. 10 further shows a transmission method that can be executed in a scheduling entity such as a network node, a base station, an access point, or another terminal that executes a scheduling function. This method can include a step (1000) of generating control information. This step includes a step of setting a modulation and coding scheme (MCS) indicator to a value that does not indicate an MCS in order to indicate that codewords from a plurality of codewords in a plurality of subframes are invalidated. Next, control information including such an MCS field value and further parameters that can also be set is transmitted to the UE in a transmission signal (1010). The control information transmitted includes, in particular, a resource grant for a plurality of subframes and a plurality of codewords in each subframe, and an MCS indicator that is common to the plurality of granted subframes and individual to each of the plurality of codewords, and the MCS indicator takes one of a plurality of values including a value indicating one of the plurality of MCSs and at least one value that does not indicate an MCS. The control information can also include precoding instruction information common to a plurality of subframes as described above. In step 1090, data is received (and retrieved from resources) according to the control information.

[0171] FIG. 11 shows another embodiment of the method according to the present disclosure. A method of receiving resource grants for a plurality of subframes in a communication system includes receiving a signal including control information (1120). The control information includes a common resource grant for a plurality of subframes and a plurality of codewords of each subframe, and codeword indication information indicating activation or deactivation of one or more codewords of each of the plurality of subframes. Accordingly, in step 1130, the resource grant is retrieved, and in step 1140, the codeword indication information (CWI) is retrieved, whereby for each subframe, whether the codewords from the plurality of codewords in that subframe are to be activated or deactivated according to the codeword indication information, and / or which codewords are to be activated or deactivated, is determined. Then, using the settings received in the control information in step 1120, i.e., in the granted resources in the plurality of subframes and with the codewords activated / deactivated on a subframe-by-subframe basis according to the retrieved codeword indication information (CWI), data is transmitted (1170).

[0172] Furthermore, as shown in FIG. 11, a method of transmitting resource grants for a plurality of subframes in a communication system includes, for each subframe, selecting whether the codewords from the plurality of codewords in that subframe are to be activated or deactivated, and setting codeword indication information accordingly, thereby generating control information (1100). The method further includes transmitting a signal including control information including a common resource grant for a plurality of subframes and a plurality of codewords of each subframe, and codeword indication information indicating activation or deactivation of one or more codewords of each of the plurality of subframes (1110).

[0173] In the context of the embodiments and examples presented in this specification, the description often states, for example, that "one codeword is invalidated and one codeword is validated." Generally, unless otherwise specified, without loss of generality, it should be understood that an advantageous embodiment of one invalidated codeword and one validated codeword is to validate the first codeword and invalidate the second codeword (for example, in the context of FIG. 7, the first codeword is codeword 0 and the second codeword is codeword 1).

[0174] So far in the description, examples related to codeword activation / invalidation have been provided. Note that in LTE, each codeword has a transport block mapped to it. This mapping is known to the transmitter and receiver. The mapping can generally be controlled by being predefined, or preconfigured, or by predefined rules. On the other hand, the concepts so far can also be directly applied to the activation / invalidation of transport blocks.

[0175] In LTE / LTE-A, when only codeword 0 is activated, there is still a choice as to whether transport block 1 is mapped to codeword 0 or transport block 2 is mapped to codeword 0, and this choice is particularly relevant when invalidating codewords to improve the retransmission of previously transmitted transport blocks. The mapping of transport blocks to codewords is defined in Table 5.3.3.1.5-2 of Non-Patent Document 4 shown below when only one codeword (and thus only one of the two transport blocks) is activated.

Table 1

[0176] In the embodiments and examples presented in this specification, in such cases, it is determined which transport block (1 or 2) is enabled and which transport block is disabled (2 or 1), and thus the corresponding enabled transport block is mapped to codeword 0. For example, according to an embodiment in which (one or more) codewords are enabled / disabled using the MCS field value described above, when the MCS1 indicator has a value within the range of 29 to 31, as a result, codeword 0 is disabled and codeword 1 is enabled, and further, transport block 1 is disabled and transport block 2 is mapped to codeword 1. On the other hand, when the MCS2 indicator has a value within the range of 29 to 31, as a result, codeword 0 is enabled and codeword 1 is disabled, and further, transport block 2 is disabled and transport block 1 is mapped to codeword 0. As will be apparent to those skilled in the art, this LTE mapping is one option. However, there may be other rules for the mapping between the transport block and the codeword. The present disclosure is applicable using any such rules.

[0177] Briefly, the present disclosure provides an apparatus for receiving resource grants for a plurality of subframes in a communication system, the apparatus comprising control information including: a resource grant for a plurality of subframes and a plurality of codewords of each subframe; precoding indication information common to the plurality of subframes; and a modulation and coding scheme (MCS) indicator that is common to the plurality of granted subframes and individual to each of the plurality of codewords, the MCS indicator taking one of a plurality of values including a value indicating one of a plurality of MCSs and at least one value not indicating an MCS; a transceiver for receiving a signal comprising the control information; and a processing device configured to determine that a codeword from a plurality of codewords in a plurality of subframes is invalidated when the MCS indicator for at least one of the plurality of codewords has a value not indicating an MCS, and to determine that it is not invalidated otherwise.

[0178] For example, the plurality of values includes 32 indexed values, and among these 32 values, the three values with the largest indices do not indicate an MCS and can be used to indicate invalidation of the codewords of the plurality of subframes.

[0179] For example, the control information further comprises redundancy version indication information that is individual to each of the plurality of subframes and common to all codewords in each subframe, and the processing device is configured to determine that a codeword from a plurality of codewords in a plurality of subframes is invalidated when the MCS indicator for at least one of the plurality of codewords has a value not indicating an MCS and the redundancy version indication information has a first predefined value, and to determine that it is not invalidated otherwise.

[0180] In particular, in a subframe in which one codeword is enabled and one codeword is disabled, it is advantageous that the processing device is configured to determine the redundant version of the enabled codeword based on a specific value that does not indicate the MCS and that is used together with redundant version indication information to indicate the disabling of the disabled codeword.

[0181] Furthermore, in one example, in a subframe in which two codewords are enabled and neither codeword is disabled, the processing device is configured to determine the MCS of the enabled codeword based on a specific value that indicates the MCS and that is not used together with redundant version indication information to indicate the disabling of the disabled codeword.

[0182] The precoding indication information indicates a combination of transmission precoding matrix indication information (TPMI) and the number of transmission layers, that is, it indicates a combination of TPMI and the number of transmission layers among a plurality of predefined combinations of TPMI and the number of transmission layers, or it indicates a combination of TPMI and the number of transmission layers among a plurality of combinations of TPMI and the number of transmission layers in a set of candidates preconfigured by semi-static signaling, or it indicates a combination of TPMI and the number of transmission layers among a plurality of predefined combinations of TPMI and the number of transmission layers that is also selectable in the case of a single-layer setting using one codeword per subframe, or it indicates a combination of TPMI and the number of transmission layers among a plurality of predefined combinations of TPMI and the number of transmission layers that is not selectable in the case of a single-layer setting, and it is advantageous that the value of the precoding indication information indicating each combination of TPMI and the number of transmission layers that is not selectable in the case of a single-layer system is a reserved value in the precoding indication information for the single-layer setting.

[0183] The present disclosure provides an apparatus for receiving resource grants for a plurality of subframes in a communication system, the apparatus comprising a transceiver that receives a signal comprising control information including a common resource grant for the plurality of subframes and a plurality of codewords for each subframe, and codeword indication information indicating activation or deactivation of one or more codewords for each of the plurality of subframes, and a processing device configured to determine, for each subframe, whether a codeword from the plurality of codewords in the subframe is activated or deactivated according to the codeword indication information and / or which codeword is activated or deactivated.

[0184] For example, the codeword indication information is a bitmap including individual bits for each of the plurality of subframes, each individual bit indicating whether one codeword is activated or two codewords are activated.

[0185] The control information is common to the plurality of granted subframes and further comprises a modulation and coding scheme (MCS) indicator for each of the plurality of codewords, the MCS indicator taking one of a plurality of values including a value indicating one of the plurality of MCSs and at least one value not indicating an MCS, and the processing device is further configured to determine the modulation and coding scheme of each activated codeword according to the MCS indicator taking a value indicating one of the plurality of MCSs, which is advantageous.

[0186] For example, the processing device is further configured to determine a precoding setting based on the MCS indicator taking a value not indicating one of the plurality of MCSs when one codeword is activated, or to determine which codeword is deactivated based on the MCS indicator taking a value not indicating one of the plurality of MCSs, or based on a redundancy version indicator for a subframe in which one codeword is activated.

[0187] Provided is a transmitting device corresponding to a receiving device. In particular, there is provided a device for transmitting resource grants for a plurality of subframes in a communication system, the device comprising: a processing device configured to set a modulation and coding scheme (MCS) indicator to a value that does not indicate an MCS in order to indicate that codewords from a plurality of codewords in a plurality of subframes are invalidated; resource grants for a plurality of subframes and a plurality of codewords of each subframe; precoding indication information common to the plurality of subframes; and an MCS indicator that is common to the plurality of granted subframes and individual for each of the plurality of codewords, the MCS indicator taking one of a plurality of values including a value indicating one of a plurality of MCSs and at least one value that does not indicate an MCS, and a transceiver for transmitting a signal comprising the control information.

[0188] Further provided is a device for transmitting resource grants for a plurality of subframes in a communication system, the device comprising: a processing device configured to select, for each subframe, whether codewords from a plurality of codewords in that subframe are to be validated or invalidated, and to set codeword indication information accordingly; a common resource grant for a plurality of subframes and a plurality of codewords of each subframe; and codeword indication information indicating validation or invalidation of one or more codewords of each of the plurality of subframes, and a transceiver for transmitting a signal comprising the control information.

[0189] Advantageously, the format and content of the transmitted control information are similar to the format and content described above in relation to the receiving device.

[0190] The present disclosure relates to a method for receiving resource grants for a plurality of subframes in a communication system, the method comprising receiving a signal comprising control information comprising: a resource grant for a plurality of subframes and a plurality of codewords for each subframe; precoding indication information common to the plurality of subframes; and a modulation and coding scheme (MCS) indicator that is common to the plurality of granted subframes and individual to each of the plurality of codewords, the MCS indicator taking one of a plurality of values including a value indicating one of a plurality of MCSs and at least one value not indicating an MCS; and determining that a codeword from a plurality of codewords in a plurality of subframes is invalidated if the MCS indicator for at least one of the plurality of codewords has a value not indicating an MCS, and determining that it is not invalidated otherwise.

[0191] Furthermore, provided is a method for receiving resource grants for a plurality of subframes in a communication system, the method comprising receiving a signal comprising control information comprising: a common resource grant for a plurality of subframes and a plurality of codewords for each subframe; and codeword indication information indicating activation or deactivation of one or more codewords of each of the plurality of subframes; and for each subframe, determining whether a codeword from a plurality of codewords in that subframe is activated or deactivated according to the codeword indication information, and / or which codeword is activated or deactivated.

[0192] Furthermore, a corresponding transmission method is provided. In particular, a method for transmitting resource grants for a plurality of subframes in a communication system, the method comprising the steps of: setting a modulation and coding scheme (MCS) indicator to a value that does not indicate an MCS in order to indicate that codewords from a plurality of codewords in a plurality of subframes are invalidated; a resource grant for a plurality of subframes and a plurality of codewords in each subframe; precoding indication information common to the plurality of subframes; and an MCS indicator that is common to the plurality of subframes granted and is individual to each of the plurality of codewords, the MCS indicator taking one of a plurality of values including a value indicating one of a plurality of MCSs and at least one value that does not indicate an MCS; and transmitting a signal comprising control information comprising the MCS indicator.

[0193] Furthermore, a method for transmitting resource grants for a plurality of subframes in a communication system, the method comprising the steps of: for each subframe, selecting whether codewords from a plurality of codewords in that subframe are to be validated or invalidated, and setting codeword indication information accordingly; a common resource grant for a plurality of subframes and a plurality of codewords in each subframe; and codeword indication information indicating validation or invalidation of one or more codewords in each of the plurality of subframes; and transmitting a signal comprising control information comprising the codeword indication information.

[0194] The format and content of the control information can advantageously be the same as the format and content described above in relation to the receiving device and exemplified in the above disclosure.

[0195] According to another embodiment, there is provided a (non-transitory) computer-readable medium storing a program which, when executed on a computer, performs the steps of the method described above.

[0196] [Implementation of the Present Disclosure by Hardware and Software] Another exemplary embodiment relates to implementing the various embodiments described above using hardware, software, or software in cooperation with hardware. In this regard, a user terminal (mobile terminal) and an eNodeB (base station) are provided. The user terminal and the base station are configured to execute the methods described herein and include corresponding entities (receivers, transmitters, processors, etc.) that appropriately participate in these methods.

[0197] It is further recognized that the various embodiments can be implemented or executed using a computing device (processor). The computing device or processor can be, for example, a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, etc. The various embodiments can also be executed or embodied by a combination of these devices. In particular, each functional block used in the description of each of the above embodiments can be implemented by an LSI which is an integrated circuit. These functional blocks may be composed of individual chips, or may be composed of one chip so as to include some or all of the functional blocks. These chips can include the input and output of the data coupled to themselves. Depending on the degree of integration, the LSI is called an IC, a system LSI, a super LSI, or an ultra LSI. However, the technology for implementing the integrated circuit is not limited to the LSI, and can be achieved by using a dedicated circuit or a general-purpose processor. Furthermore, an FPGA that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection or setting of the circuit cells inside the LSI may be used.

[0198] Furthermore, various embodiments can also be implemented by software modules. These software modules can be executed by a processor or directly executed in hardware. Combinations of software modules and hardware implementations are also possible. The software modules can be stored in any type of computer-readable storage medium, such as RAM, EPROM, EEPROM, flash memory, registers, hard disk, CD-ROM, DVD, etc. Further, it should be noted that the individual features of multiple different embodiments can be made the subject of another embodiment, individually or in any combination.

[0199] Those skilled in the art will understand that various changes and / or modifications can be made to the present disclosure shown in the specific embodiments without departing from the concept or scope of the present invention described in a broad sense. Therefore, the embodiments shown in this specification are considered to be illustrative in every respect and not restrictive of the present invention.

[0200] In summary, the present disclosure relates to the activation and deactivation of codewords in a multi-subframe grant. Specifically, another control parameter including resource allocation enables the codewords to be dynamically activated / deactivated on a per-subframe basis even when executed for a plurality of subframes. For example, a signal from an entity scheduling to an entity being scheduled includes control information including a common resource grant for a plurality of subframes and a plurality of codewords in each subframe, and codeword indication information indicating activation or deactivation of one or more codewords in each of the plurality of subframes. For each subframe, it is determined whether the codewords from the plurality of codewords in that subframe are activated or deactivated according to the codeword indication information, and / or which codewords are activated or deactivated. Alternatively, the activation and deactivation instructions can be made by using a modulation and coding scheme indicator value not associated with a specific modulation and coding scheme.

Claims

1. An integrated circuit for controlling a user equipment that receives resource grants for a plurality of subframes in a communication system, the integrated circuit comprising: the resource grants for the plurality of subframes and the plurality of codewords of each subframe; precoding indication information common to the plurality of subframes; a modulation and coding scheme (MCS) indicator that is common to the plurality of granted subframes and is individual to each of the plurality of codewords of each subframe, taking one of a plurality of values including a value indicating one of a plurality of MCSs and at least one value not indicating an MCS; a receiving circuit that receives a signal including control information including; a control circuit that invalidates the first codeword or the second codeword according to whether a different redundancy version (RV) indicates a first RV state or a second RV state for each subframe, where the plurality of codewords include a first codeword and a second codeword, the first MCS indicator has a value indicating one of the MCSs, and the second MCS indicator has a value not indicating an MCS; having an integrated circuit.

2. The integrated circuit according to claim 1, wherein when the RV indicates the first RV state, the first codeword is invalidated, and when the RV indicates the second RV state, the second codeword is invalidated. The integrated circuit according to claim 1.

3. The integrated circuit according to claim 1, wherein the precoding indication information indicates a combination of transmission precoding matrix indication information (TPMI) and the number of transmission layers. The integrated circuit according to claim 1.

4. The combination of the TPMI and the number of transmission layers is a combination of the TPMI and the number of transmission layers among a plurality of predefined combinations of the TPMI and the number of transmission layers. The integrated circuit according to claim 3.

5. The combination of the TPMI and the number of transmission layers is a combination of the TPMI and the number of transmission layers among a plurality of combinations of the TPMI and the number of transmission layers in a set of candidates pre-set by semi-static signaling. The integrated circuit according to claim 3.

6. The combination of the TPMI and the number of transmission layers is The value of the pre-coding instruction information indicating each combination of the TPMI and the number of transmission layers, which is selectable even in the case of a single-layer setting using one codeword per sub-frame, or among a plurality of predefined combinations of the TPMI and the number of transmission layers that are not selectable in the case of a single-layer setting, and which is not selectable in the case of a single-layer system, is a reserved value in the pre-coding instruction information for the single-layer setting. The integrated circuit according to claim 3.

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