JP5685564B2 - Method and apparatus for encoding uplink acknowledgment for downlink transmission - Google Patents

Description

  The present invention relates to wireless communication, and more particularly, to an apparatus and method for encoding an uplink response to a downlink transfer.

  One multi-carrier communication scheme transfers data through a number of orthogonal subcarriers. Such example systems typically require high transfer rates and include wireless short range networks (LANs) and mobile Internet technologies. Typical multi-carrier communication schemes are Orthogonal Frequency Division Multiplexing (OFDM), Discrete Fourier Transform-Spread-Orthogonal Frequency Division Multiplexing (DFT-S-OFDM or DET-Spreading-OFDM) (both SC-FDMA). And Orthogonal Frequency Division Multiplexing Access (OFDMA). OFDM and OFDMA can obtain a high transmission rate by maintaining the orthogonality of subcarriers, but often have a high peak-to-average power ratio (PAPR). The DFT-S-OFDMA is implemented to overcome the PAPR problem. For example, the DFT-S-OFDMA can be performed by first spreading signals using a DFT matrix in a frequency domain before generating an OFDM signal. Function. These spread signals can be modulated and transferred in a well-known manner using conventional OFDM technology. This technique will be described as follows.

  FIG. 1 is a flowchart illustrating generation of a transfer signal by a conventional DFT-S-OFDMA system. According to blocks 110 and 120, a typical DFT-S-OFDM wireless communication system spreads the signal using a DFT matrix before generating an OFDM signal. Assuming that “s” is an input data symbol, “x” is data spread in the frequency domain, and “Nb” is the number of subcarriers for a specific user, the spread data “x” Can be obtained from the formula:

ブロック１３０、１４０及び１５０によると、拡散ベクトル（ｓｐｒｅａｄ ｖｅｃｔｏｒ）“ｘ”は、副搬送波マッピング技術によって副搬送波にマッピングされたことを示し、受信エンティティ（ｒｅｃｅｉｖｉｎｇ ｅｎｔｉｔｙ）への転送のための信号を獲得するために逆離散フーリエ変換（Ｉｎｖｅｒｓｅ Ｄｉｓｃｒｅｔｅ Ｆｏｕｒｉｅｒ
Ｔｒａｎｓｆｏｒｍ：ＩＤＦＦ）モジュールを経て時間領域に変換される。転送信号“ｙ”は、下記のようにして得られる：

According to blocks 130, 140 and 150, a spread vector “x” indicates that it has been mapped to a subcarrier by a subcarrier mapping technique and obtains a signal for transfer to a receiving entity. Inverse Discrete Fourier Transform (Inverse Discrete Fourier Transform)
It is converted into the time domain through a Transform (IDFF) module. The transfer signal “y” is obtained as follows:

このような方式で生成される信号“ｙ”は、挿入された循環前置（ブロック１６０）と共に転送される。

The signal “y” generated in this way is transferred with the inserted cyclic prefix (block 160).

  Data, pilot and control information are then transferred on the uplink of a multi-carrier system including, for example, DFT-S-OFDM. The control information is divided into data-related control information related to data demodulation and non-data-associated control information not related to data demodulation.

  The data-related control information includes control information necessary for recovering data transferred by a terminal (User Equipment: UE). For example, the data-related control information may include information related to a transfer format or information related to a hybrid automatic repeat request (HARQ). The amount of data related control information can be adjusted according to the uplink data scheduling scheme.

  On the other hand, non-data related control information is control information necessary for downlink transfer. For example, non-data related control information includes acknowledgment (ACK) or negative acknowledgment (NACK) information for HARQ operation, and channel quality indicator (CQI) for downlink link adaptation. ) Can be included.

  In uplink multi-carrier or single-carrier FDMA systems, the control information is divided into data related control information for demodulating user data and non-data related control information for downlink transmission. The basic principle of OFDM is that a data stream having a high transfer rate is divided into a large number of data streams, and each divided data stream has a low transfer rate and is simultaneously transferred via a large number of carriers. is there. Each carrier is called a subcarrier. Since orthogonality exists between OFDM carriers, the transmitting end can still detect the frequency components even if the frequency components of each carrier are superimposed on each other.

  A data stream having a high transfer rate is converted into a number of data streams having a low transfer rate through a serial-parallel converter. Each parallel-converted data stream is multiplied by a corresponding subcarrier, summed together, and then transferred to the receiving end.

  The parallel data stream generated by the serial-to-parallel converter can be transferred as a number of subcarriers by the IDFT. The IDFT can be efficiently performed using an inverse fast Fourier transform (IFFT).

  As the symbol period of subcarriers with low rate increases, the associated signal dispersion caused by multi-path delay spread decreases in the time domain. Inter-symbol interference (ISI) can be reduced by inserting a guard interval (GI) longer than the channel delay spread between OFDM symbols. When a portion of the OFDM signal is copied into the guard interval and placed at the beginning of the symbol, the OFDM symbol is cyclically extended and protected.

  If a sufficient number of subcarriers are allocated to non-data related control information when a terminal (UE) transfers control information in the uplink, the amount of frequency resources used for data transfer can be reduced. As a result, this technique results in a large number of subcarriers not being assigned, thus affecting the ability to obtain diversity gain in the frequency domain.

  A typical terminal individually transmits ACK / NACK and CQI signals of non-data related control information on the uplink. For example, the terminal transmits an ACK / NACK signal, a CQI signal, or both of these signals in a special time period. However, the conventional multi-carrier system does not separately process each signal constituting the non-data related control information, which leads to an efficient use of frequency resources.

  The ACK / NACK and CQI signals are transferred using a single discrete Fourier transform on the uplink of the DFT-S-OFDM communication system. Many users typically share the same resource unit. For example, if a user with the same resource unit transfers an ACK / NACK signal and another user transfers a CQI signal, the base station demodulates the ACK / NACK and CQI signals of the two users. Can be impossible.

  The features and advantages of the invention are set forth below, and in part will be obvious from the description, or may be obtained by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

  According to one embodiment, a method for encoding an uplink acknowledgment for a downlink transfer includes receiving a number of data blocks each including a cyclic redundancy check (CRC) code. The method further includes determining the reception status for each data block by examining the CRC of each data block and generating a response sequence representing the reception status of all these data blocks.

  According to one feature, these data blocks include a primary transport block and a secondary transport block.

  According to another feature, the response sequence is a discrete response sequence.

  According to still other features, the method further includes generating the response sequence as a single response sequence indicating the reception status of all data blocks.

  According to yet another feature, a data block is received from Node B.

  According to one aspect, the state is an acknowledgment (ACK) that confirms that the data block was received correctly or a negative acknowledgment (NACK) that confirms that the data block was not received correctly.

  According to another aspect, the method further includes modulating the response sequence using QPSK modulation.

  According to yet another aspect, the method further includes forwarding the response sequence to the Node B.

  According to still another aspect, the downlink transfer includes multiple input multiple output (MIMO) transfer.

  According to one feature, the method further comprises receiving data blocks in parallel.

  According to another feature, the downlink transfer includes a Time Division Duplex (TDD) transfer.

  According to still other features, the method further includes receiving data blocks sequentially or receiving data blocks in parallel.

  According to another embodiment, a method for receiving an encoded uplink acknowledgment for a downlink transfer includes transferring multiple data blocks including respective cyclic redundancy check (CRC) codes in parallel. The method further includes receiving a single response sequence representing the reception status of all these data blocks.

  According to yet another embodiment, a portable device encoding an uplink acknowledgment for downlink transmission includes a receiver configured to receive a number of data blocks each including a cyclic redundancy check code, and each data block And a processor configured to determine the reception status of each data block by examining the CRC of the data block. The portable device further includes a transfer device that transfers a response sequence representing the reception status of all data blocks.

  According to yet another embodiment, a forwarding entity operable for a wireless communication system and configured to receive an encoded uplink acknowledgment for downlink forwarding is a cyclic redundancy check (CRC). A transmitter for transferring a number of data blocks each containing a code in parallel; and a receiver for receiving a single response sequence representing the reception status of all the data blocks.

  According to yet another embodiment, a method for encoding an uplink acknowledgment for downlink transmission includes receiving a plurality of data blocks each including a cyclic redundancy check (CRC) code, and receiving a CRC for each data block. Determining a reception state for each data block by checking and generating a response bit according to the state. The method maps a response bit to a fixed length sequence, generates a mapped sequence, forwards the mapped sequence in an uplink transfer, and maps and forwards the mapping and transfer to a predetermined sequence. Repeating with a time period.

These and other embodiments will be apparent to those skilled in the art from the detailed description of the embodiments with reference to the accompanying drawings, and the present invention is not limited to any particular embodiments disclosed. .
The present invention also provides the following items.
(Item 1)
In a method of encoding an uplink acknowledgment for a downlink transfer,
Receiving a number of data blocks each including a cyclic redundancy check (CRC) code;
Determining a reception state for each data block by examining a CRC of each data block;
Generating a response sequence representing the reception status of all the data blocks;
Encoding method, including
(Item 2)
The encoding method according to claim 1, wherein the data block includes a first transport block and a second transport block.
(Item 3)
The encoding method according to item 1, wherein the response sequence is a discrete response sequence.
(Item 4)
The encoding method according to item 1, further comprising the step of generating the response sequence as a single response sequence representing a reception state of all the data blocks.
(Item 5)
The encoding method according to item 1, wherein the data block is received from a base station.
(Item 6)
Item 2. The item according to item 1, wherein the state is an affirmative confirmation state (ACK) for confirming that the data block has been correctly received or a negative confirmation state (NACK) for confirming that the data block has not been correctly received. Encoding method.
(Item 7)
The encoding method according to item 1, further comprising modulating the response sequence using QPSK modulation.
(Item 8)
The encoding method according to item 1, further comprising the step of transferring the response sequence to a Node B.
(Item 9)
The encoding method according to item 1, wherein the downlink transfer includes a multiple input multiple output (MIMO) transfer.
(Item 10)
The encoding method according to item 9, further comprising receiving the data block in parallel.
(Item 11)
The encoding method according to item 1, wherein the downlink transfer includes a time division duplex (TDD) transfer.
(Item 12)
12. The encoding method according to item 11, further comprising: sequentially receiving the data blocks.
(Item 13)
12. The encoding method according to item 11, further comprising receiving the data block in parallel.
(Item 14)
In a method of receiving an encoded uplink acknowledgment for a downlink transfer,
Transferring in parallel a number of data blocks each containing a cyclic redundancy check (CRC) code;
Receiving a single response sequence representing the reception status of all the data blocks;
Including a receiving method.
(Item 15)
15. The reception method according to item 14, wherein the data block includes a first transport block and a second transport block.
(Item 16)
15. The reception method according to item 14, wherein the data block is transferred from a base station.
(Item 17)
15. The item according to item 14, wherein the state is an affirmative confirmation state (ACK) for confirming that the data block has been correctly received or a negative confirmation state (NACK) for confirming that the data block has not been correctly received. Reception method.
(Item 18)
Item 15. The reception method according to Item 14, wherein the response sequence is modulated using QPSK modulation.
(Item 19)
Item 15. The reception method according to Item 14, wherein the downlink transfer includes multiple input multiple output (MIMO) transfer.
(Item 20)
15. A receiving method according to item 14, wherein the downlink transfer includes a time division duplex (TDD) transfer.
(Item 21)
In a mobile device that encodes an uplink acknowledgment for a downlink transfer,
A receiver configured to receive a number of data blocks each including a cyclic redundancy check (CRC) code;
A processor configured to determine a reception state for each data block by examining a CRC of each data block;
A transfer device for transferring a response sequence indicating a reception state of all the data blocks;
Including portable devices.
(Item 22)
The mobile device according to item 21, wherein the data block includes a first transport block and a second transport block.
(Item 23)
Item 22. The mobile device according to Item 21, wherein the response sequence is a discrete response sequence.
(Item 24)
24. The portable device of item 21, wherein the processor is further configured to generate the response sequence as a single response sequence that represents a reception status of all the data blocks.
(Item 25)
Item 22. The portable device of item 21, wherein the receiver is further configured to receive the data block from a base station.
(Item 26)
22. The item according to item 21, wherein the state is an affirmative confirmation state (ACK) for confirming that the data block has been correctly received or a negative confirmation state (NACK) for confirming that the data block has not been correctly received. Portable device.
(Item 27)
Item 22. The portable device of item 21, wherein the processor is further configured to modulate the response sequence using QPSK modulation.
(Item 28)
Item 22. The portable device of item 21, wherein the forwarder is further configured to forward the response sequence to a base station.
(Item 29)
Item 22. The portable device according to Item 21, wherein the downlink transfer includes multiple I / O transfer.
(Item 30)
30. The portable device of item 29, wherein the receiver is further configured to receive the data block in parallel.
(Item 31)
Item 22. The mobile device of item 21, wherein the downlink transfer comprises a time division duplex (TDD) transfer.
(Item 32)
32. The portable device of item 31, wherein the receiver is further configured to sequentially receive the data blocks.
(Item 33)
32. The portable device of item 31, wherein the receiver is further configured to receive the data block in parallel.
(Item 34)
In a forwarding entity configured to receive an encoded uplink acknowledgment for downlink forwarding and operable in a wireless communication system,
A transfer device for transferring in parallel a number of data blocks each including a cyclic redundancy check (CRC) code;
And a receiver that receives a single response sequence representing the reception status of all the data blocks.
(Item 35)
35. The transport entity according to item 34, wherein the data block includes a primary transport block and a secondary transport block.
(Item 36)
35. The forwarding entity of item 34, wherein the forwarder is further configured to forward the data block from a base station.
(Item 37)
35. The item of item 34, wherein the state is an affirmative confirmation state (ACK) that confirms that the data block was received correctly, or a negative confirmation state (NACK) that confirms that the data block was not received correctly. Transfer entity.
(Item 38)
35. The forwarding entity of item 34, further comprising a modulator that modulates the response sequence using QPSK modulation.
(Item 39)
35. The forwarding entity according to item 34, wherein the downlink forwarding includes a multiple input multiple output (MIMO) forwarding.
(Item 40)
35. A forwarding entity according to item 34, wherein the downlink forwarding comprises a time division duplex (TDD) forwarding.
(Item 41)
In a method of encoding an uplink acknowledgment for a downlink transfer,
Receiving a number of data blocks each including a cyclic redundancy check (CRC) code;
Determining a reception state for each data block by examining a CRC of each data block;
Generating a response bit according to the state;
Mapping the response bits to a fixed length sequence to generate a mapped sequence;
Transferring the mapped sequence in uplink transfer;
Repeating the mapping and transfer at a predetermined time period;
Encoding method, including
(Item 42)
Generating a response bit; and
Mapping the response bits to a fixed length sequence to generate a mapped sequence;
The encoding method according to item 41, further comprising:

It is a flowchart which shows the production | generation of the transfer signal by the conventional DFT-S-OFDMA system. FIG. 6 is a diagram illustrating uplink terminal transmission in which control information vectors are collectively spread to obtain a spreading vector. FIG. 6 is a diagram illustrating another arrangement for uplink transmission in a DFT-S-OFDM wireless communication system according to an embodiment of the present invention; FIG. 6 is a diagram illustrating still another arrangement for uplink transmission in a DFT-S-OFDMA wireless communication system according to an embodiment of the present invention; FIG. 2 is a diagram illustrating an uplink subframe format using time division duplex (TDD) in a DFT-S-OFDM wireless communication system. 1 is a diagram illustrating an uplink subframe format using frequency division duplex (FDD) in a DFT-S-OFDM wireless communication system. FIG. FIG. 6 is a block diagram illustrating a technique for reducing BER in a transmission terminal operation within a DS-OFDM wireless communication system according to an embodiment of the present invention. FIG. 6 is a block diagram illustrating a technique for reducing BER in a transmission terminal operation within a DS-OFDM wireless communication system according to an embodiment of the present invention. FIG. 5 is a block diagram illustrating a method for selecting an assigned subcarrier according to an embodiment of the present invention. It is a figure which shows an uplink sub-frame format. FIG. 3 is a diagram illustrating an uplink multiplexing scheme. FIG. 3 is a diagram illustrating an uplink multiplexing scheme. FIG. 6 is a diagram illustrating an embodiment related to allocating frequency resources for ACK / NACK signal transfer in uplink of SC-FDMA / OFDMA system. FIG. 6 is a diagram illustrating an embodiment related to allocating frequency resources for ACK / NACK signal transfer in uplink of SC-FDMA / OFDMA system. FIG. 6 is a diagram illustrating an embodiment related to allocating frequency resources for ACK / NACK signal transfer in uplink of SC-FDMA / OFDMA system. It is a figure which shows the SCW and MCW transmission end comprised for using in a MIMO wireless mobile communication system. It is a figure which shows the SCW and MCW transmission end comprised for using in a MIMO wireless mobile communication system. 1 is a block diagram illustrating an ACK / NACK transfer apparatus according to an embodiment of the present invention. FIG. 6 is a block diagram illustrating an ACK / NACK transfer apparatus according to another embodiment of the present invention. It is a figure which shows the regional allocation of many subcarriers. FIG. 6 is a diagram illustrating distributed allocation of multiple subcarriers. It is a figure which shows the method of carrying out uplink transmission using OFDM. It is a flowchart which shows the production | generation of the transfer signal by DFT-S-OFDMA. It is a figure which shows an example of the subcarrier arrange | positioned closely. It is a figure which shows an example of the subcarrier arrangement | positioning using the improved area allocation. It is a figure which shows distribution of the subcarrier for ACK / NACK signal transmission. FIG. 6 is a diagram illustrating a subcarrier arrangement in which two subcarriers are configured as one group using improved distributed allocation. FIG. 6 is a diagram illustrating a subcarrier arrangement in which two subcarriers are configured as one group using improved distributed allocation. It is a figure which shows an additional subcarrier arrangement | positioning. It is a figure which shows an additional subcarrier arrangement | positioning.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is obvious to those skilled in the art that in other embodiments, not only procedural changes but also structural and electrical changes can be made without departing from the scope of the present invention. In the drawings, the same components are denoted by the same reference numerals as much as possible.

  Hereinafter, various embodiments will be disclosed in association with a terminal. However, these techniques can also be applied to other types of wireless terminals such as mobile terminals and mobile stations.

Spreading Control Information Vector on Uplink FIGS. 2A-2C are block diagrams illustrating various elements of an uplink forwarding entity operable in a DFT-S-OFDM wireless communication system according to an embodiment of the present invention. First, consider a terminal configured as a forwarding entity in such a communication system. The terminal receives and distinguishes control information such as ACK / NACK, channel quality indicator (CQI) and other forms of non-data related control information. Such control information is not related to data demodulation. In general, an ACK / NACK is a vector containing one or more bits based on the number of cyclic redundancy check codes (CRCs) inserted in the downlink signal. In general, the CQI is a vector containing a number of bits that report the channel quality status to the associated base station or Node B, for example. CQI facilitates downlink scheduling at the base station. Hereinafter, an embodiment in which the size of the ACK / NACK vector is “l” and the size of the CQI vector is “m” will be described, but the embodiment is not limited thereto.

FIG. 2A shows a UE transfer on the uplink that collectively spreads the control information vector (which has become l + m magnitude through DFT) in order to obtain a spreading vector (X ′ _{ACK + CQI} ) with n = l + m magnitude bits. FIG. In another operation, the vector (X ″ _{ACK + CQI} ) obtained by the subcarrier mapping is _subjected to inverse fast Fourier transform (IFFT) to acquire and transfer time information (y ′ _{ACK + CQ} ).

In this scenario, one of the terminal transfers the ACK / NACK, if other terminals for transferring CQI using the same resource _block, X _{'ACK + CQI} to be acquired by removing the respective sub-carrier from the _{X "ACK + CQI} vector It is difficult to select an IDFT because the receiving base station despreads the vector. The vector X ″ _{ACK + CQI} is obtained by the base station through a fast Fourier transform (FFT) corresponding to the IFFT performed at the transmitting end. Can do. The signal transferred by the terminal is typically spread _{indifferently} into the vector X ″ _{ACK + CQI} and the vector X ′ _{ACK + CQI} . This is received from two or more terminals if the terminal uses the same resource block. This is because it is necessary to distinguish between IDFTs used for analyzing the received signals.

FIG. 2B is a diagram illustrating another arrangement for uplink transmission in a DFT-S-OFDM wireless communication system according to an embodiment of the present invention. A terminal configured to transfer according to FIG. 2B distinguishes and receives various types of control information as described above. In this embodiment, the terminal spreads ACK / NACK and CQI control information using different DFTs before mapping these parameters to the corresponding subcarriers. Since vector ACK / NACK of magnitude 1 (X _ACK ) and vector CQI of magnitude m (X _CQI ) are spread using different DFTs, these spreading vectors of magnitude 1 and m (X ′ _ACK ) and ( X ′ _CQI ) also includes ACK / NACK information and CQI information, respectively.

Spreading vectors X ′ _ACK and X ′ _CQI are mapped to corresponding subcarriers, IFFT converted, and then transferred to the base station. According to this embodiment, when one terminal transmits ACK / NACK using the same resource block and another terminal transmits CQI information, each subcarrier is removed from the vectors X ″ _ACK and X ″ _CQI respectively. An IDFT for despreading the acquired vectors X ′ _ACK and X ′ _CQI can be easily selected. The vectors X ″ _ACK and X ″ _CQI can be obtained by the base station through an FFT corresponding to IFFT performed at the transmitting end, which is a terminal in the illustrated example.

  FIG. 2B is an example of partitioning between control information such as ACK / NACK and CQI. However, other forms of information can be similarly segmented using the illustrated techniques. For example, the technique of FIG. 2B may also be applied to situations where two or more control signals (information) are received and mapped using different DFTs before mapping to frequency resources for transmission over the uplink. Can do. This allows a receiving entity that receives an uplink signal to distinguish between two or more forms of transferred control information through control information that is de-mapped from frequency resources.

  The embodiment of FIG. 2B uses an individual DFT to spread control information individually, but various alternatives are possible and can be envisaged by the present disclosure. For example, a separate DFT process can optionally include any process, but such a process is provided to allow an entity receiving an uplink signal to distinguish between different forms of control information. .

FIG. 2C is a diagram illustrating another structure for uplink transmission in a DFT-S-OFDM wireless communication system according to an embodiment of the present invention. In this embodiment, for example, the transfer terminal directly maps the ACK / NACK control information to the subcarrier. This can be achieved without performing DFT, resulting in X ″ _ACK . In FIG. 2C, DFT is further used to transform the CQI control information, and then the spreading vector X ′ _CQI is mapped to the subcarrier and X ”Get _CQI .

  In general, the size of a vector corresponding to ACK / NACK information is smaller than the size of a vector corresponding to CQI information. Therefore, the effect achieved by spreading the vector corresponding to the ACK / NACK information is relatively small. This embodiment is simplified to the extent that DFT processing of the ACK / NACK signal is omitted. However, this embodiment can obtain the same effect as in the case of FIG. 2B because the base station can accurately classify the information items subjected to the FFT. Preferably, the embodiment of FIG. 2C may include any individual process rather than individual DFT spreading, but such a process allows the receiving entity to partition different forms of control information.

  The embodiment of FIG. 2C may further include structures that improve PAPR performance. For example, when IFFT for transfer is performed after ACK / NACK signal is directly mapped to subcarrier without DFT, the compensation effect between DFT and IFFT degrades PAPR performance (for performance This can be achieved with the configuration of FIG. 2B). Thus, the terminal configured according to FIG. 2C can select a specific subcarrier to improve PAPR performance, and can then map an ACK / NACK signal to the selected subcarrier.

  FIG. 3A is a diagram illustrating an uplink subframe format using time division multiplexing (TDM) in a DFT-S-OFDM wireless communication system. FIG. 3B is a diagram illustrating an uplink subframe format using frequency division multiplexing (FDM) in the DFT-S-OFDM wireless communication system.

  In general, in the DFT-S-OFDM wireless communication system, ACK / NACK control information is represented by one bit or one of a relatively small number of bits. As a result, the bit error rate (BER) can be slightly deteriorated due to various factors in the radio channel. Typical multiplexing methods in a DFT-S-OFDM wireless communication system include TDM (FIG. 3A) and FDM (FIG. 3B). Therefore, the transmitting terminal according to the embodiment typically repeatedly transmits ACK / NACK information in order to improve the BER.

Consider the case of TDM used by multiple terminals. In this scenario, ACK / NACK information is a long block (Long) allocated to a subframe over a specific frequency.
Block: LB) (eg, LB # 3 in FIG. 3A) can be repeatedly transferred. Such a structure typically improves the BER characteristics.

  Repetitive transfer over a specific frequency can be achieved by transferring ACK / NACK information over a frequency band or mapping ACK / NACK information to a specific sequence. DFT can be selectively performed on this ACK / NACK information. Preferably, the ACK / NACK information can also be transmitted repeatedly using block coding.

  Consider a situation where information transferred from a large number of terminals is multiplexed using FDM. In this scenario, ACK / NACK information can be recursively transferred within multiple LBs assigned to the subframe (eg, LB # 1-LB # 6 in FIG. 3B). Such a structure also typically improves the BER characteristics. In either case, multiple ACK / NACK signals can be transmitted in response to downlink information using multiple antennas. In one embodiment, the number of ACK / NACK signals is the same as the number of CRCs inserted in the downlink data (described above).

  When the CRC is inserted into each part of the information transmitted through each antenna in the downlink, the terminal transmits (in the uplink) the number of ACK / NACK signals corresponding to the number of CRCs received in response to the CRC. To do. When the terminal transmits a large number of ACK / NACK signals in this manner, the ACK / NACK signal is repeatedly transmitted at a number of specific times. Such an operation can be used to improve the BER characteristics of the forwarded ACK / NACK signal.

For example, M is the number of ACK / NACK signals. The M ACK / NACK signals can be represented by ACK / NACK ₁ , ACK / NACK ₂ ,... ACK / NACK _M and a specific time K. In this case, the ACK / NACK signal can be repeatedly transmitted as follows.
{(ACK / NACK _1-1 , ACK / NACK _1-2 ,..., ACK / NACK _1-K )
_{, (ACK / NACK 2-1, ACK} / NACK 2-2, ..., ACK / NACK 2-K)
, ..., (ACK / NACK _M-1 , ACK / NACK _M-2 , ..., ACK / NACK _M-K )} _.

Depending on the selective technique, the ACK / NACK signal can be repeatedly transmitted as follows.
{(ACK / NACK _1-1 , ACK / NACK _2-1 , ..., ACK / NACK _M-1 ), (ACK / NACK _1-2 , ACK / NACK _2-2 , ..., ACK / NACK _M-2 ) , ..., (ACK / NACK _1-K , ACK / NACK _2-K , ..., ACK / NACK _M-K
)}.

  4A and 4B are block diagrams illustrating a technique for reducing BER at a transmitting terminal in a DFT-S-OFDM wireless communication system according to an embodiment of the present invention. First, consider a case where the transmitting end transfers multiple ACK / NACK signals using multiple antennas. In this case, the transmitting end can transfer an ACK / NACK signal by performing block coding on these signals using, for example, the technique shown in FIGS. 4A and 4B.

  Referring to FIG. 4A, a technique is shown in which ACK / NACK and CQI signals are first spread using a dedicated DFT before transmission. An alternative technique is shown in FIG. 4B. In FIG. 4B, the ACK / NACK signal is directly mapped to the subcarrier without being spread through the DFT, whereas the CQI signal is spread to the subcarrier after being spread through the DFT.

  In order to improve the PAPR and BER characteristics of the ACK / NACK signal, a large number of ACK / NACK signals need not be directly transferred, but instead can be selectively mapped to a specific sequence and transferred. According to one technique, a specific sequence for mapping can be determined. One sequence can be selected, and multiple ACK / NACK signals can be mapped to this sequence. Preferably, the sequence can be selected as a specific sequence for mapping according to PAPR and BER characteristics. Alternatively, the ACK / NACK signal may be transferred after these signals are modulated using a conventional modulation scheme such as BPSK or QPSK.

  FIG. 5 is a block diagram illustrating a method for selecting a subcarrier allocated according to an embodiment of the present invention. In this technique, when ACK / NACK and CQI information is transferred, a subcarrier is selected based on a transfer state of the information.

  Allocating a sufficient number of subcarriers for non-data related control information on the uplink can reduce the number of subcarriers required to transfer terminal data. ACK / NACK and CQI information can be transferred individually as described above. However, if the sub-carrier allocation is performed when both ACK / NACK and CQI information are transferred, frequency resources can be allocated efficiently. This is a special case in which only ACK / NACK information is transferred, only CQI information is transferred, or ACK / NACK and CQI information are transferred simultaneously.

  Therefore, the transmitting terminal according to the embodiment of the present invention separately receives the ACK / NACK and CQI information among the non-data related control information in order to identify whether ACK / NACK and CQI information are respectively transferred. be able to. Based on such identification, the UE allocates a suitable subcarrier in each case where only ACK / NACK information is transferred, only CQI information is transferred, or ACK / NACK and CQI information are transferred simultaneously. be able to. In this embodiment, in order to identify whether ACK / NACK and CQI information are respectively transferred, ACK / NACK and CQI information is classified among non-data related control information. This embodiment can effectively manage frequency resources, allocate an increased amount of frequency resources for transmission, and obtain frequency diversity.

  The advantages of the various embodiments are that the terminal separates ACK / NACK and CQI information from non-data related control information not related to data demodulation and individually processes this information before mapping it to frequency resources. Including doing. This allows the control information received by the base station to be easily processed even when the base station individually receives ACK / NACK and CQI information from multiple terminals through the same resource block. Note that the BER improvement of ACK / NACK information is obtained by repeatedly transmitting ACK / NACK information in the uplink over a specific time period when FDM is applied or over a specific frequency when TDM is applied. be able to.

  When multiple ACK / NACK signals are transferred, improvements in PAPR and / or BER characteristics can also be obtained by performing a process on the transferred ACK / NACK signals. Examples of such signals include block coding, mapping to a specific sequence, modulation by BPSK or QPSK.

Frequency Resource Allocation Still other embodiments relate to allocating frequency resources for ACK / NACK transfer in an uplink multi-carrier or single carrier (SC) FDMA system. FIG. 6 is a diagram illustrating an uplink subframe format. In FIG. 6, a long block (LB) is used for data and control information transfer, and a short block (SB) is used for pilot and data transfer.

Uplink transmission by the terminal can be classified in the following cases:
-Terminal data, pilot, data related control;
-Terminal data, pilot, data related control, non-data related control;
-Pilot, non-data related control.

  In these cases, multiplexing can be performed using various multiplexing techniques shown in FIGS. 7 and 8, for example. The subframe format of FIG. 6 includes multiplexing data related control information and non-data related control information together with terminal data, and simultaneously multiplexing non-data related control information of multiple terminals.

  In FIG. 7, although the data-related control information and the terminal data are multiplexed, the predetermined time-frequency domain is determined for the transfer of non-data-related control information of a large number of terminals. When terminal data exists, non-data related control information is transferred in a band for transferring terminal data, and instead, terminal data is transferred in a band determined for non-data related control information. The advantage of this technique is that the SC-FDMA characteristics can be maintained.

  As shown in FIGS. 7 and 8, bandwidth allocation for terminal data and non-data related control is performed in the same manner. In particular, when terminal data corresponds to regional allocation, regional allocation is similarly applied to non-data related control. However, among the non-data related control information, the ACK / NACK information has a size of 1 bit and therefore cannot be channel coded. As a result, it is possible to obtain a specific error rate by repeating ACK / NACK information.

  FIGS. 9A to 9C are diagrams illustrating examples and variations thereof related to allocating frequency resources for ACK / NACK signal transfer in the uplink of the SC-FDMA / OFDMA system. In general, there are two techniques for allocating frequency resources in the uplink. One of them is a distribution method in which transfer data is arranged at equal intervals in the entire frequency band (FIG. 9A). The other is a regionalized method of arranging transfer data in a specific frequency band (FIGS. 9B and 9C).

Although the ACK / NACK signal typically has a size of 1 bit, a specific error rate can be obtained by repeating the ACK / NACK signal. For example, it is assumed that an ACK / NACK signal obtained from repetition is transferred through N resource units (RU). Similarly, in the case of repeated ACK / NACK signal transfer through NRU using a localized method, ACK / NACK is smaller than the frequency resource occupied by NRU, two additional methods are performed. Can. One is a method of assigning repeated ACK / NACK signals to continuous frequency resources, and the other is a method of arranging ACK / NACK signals in NRUs, for example, using even intervals. is there. Therefore, frequency resource allocation techniques for ACK / NACK transfer can be summarized as follows:
Distributed;
Localized;
Pure localized;
Distribution within the allocated frequency resource.

Multiple codeword ACK / NACK
Still another embodiment relates to HARQ in a mobile communication system. In particular, the present invention relates to an apparatus for transferring an ACK / NACK signal in a multiple codeword (MCW) type MIMO wireless system. As will be described, this embodiment is suitable for a wide range of applications including, for example, transmitting multiple ACK / NACK signals using multiple MCW-type transfer and receive antennas.

  Generally, in a mobile communication system, multiple transfer and reception antennas can be used to increase a transfer rate. Data transfer using multiple antennas can be obtained using two main techniques. First, data can be transferred in a transfer diversity format. In this case, the transfer rate does not increase, but the signal-to-noise ratio (SNR) of the received signal is increased to enable stable operation. This is because the same data is transferred through multiple antennas. Second, data is transferred in a spatial multiplexing format. In this case, transferring a large number of independent data streams at the same time leads to an effect of increasing the transfer rate. Therefore, transmit diversity transfer is efficient in regions with low SNR, and spatial multiplexing transfer is efficient in regions with high SNR.

  10A and 10B are block diagrams illustrating SCW and MCW transmission terminals configured for use in a MIMO wireless mobile communication system. It can be seen in many cases that multiple data streams can be transferred simultaneously. For example, after coding is performed by one channel encoder, the data is divided into a number of data streams. This technique is commonly referred to as transfer using a single codeword (SCW).

  FIG. 11 is a block diagram illustrating an ACK / NACK transfer apparatus according to an embodiment of the present invention. This embodiment provides techniques for transferring multiple streams, but includes techniques for individually encoding multiple data streams via a channel encoder and then transferring the encoded data streams. This technique is commonly referred to as transfer using multiple codewords (MCW).

  SCW technology involves splitting after one block is coded. Since one CRC for error checking is attached to each block, the receiver typically transfers only one ACK / NACK signal. On the other hand, in MCW, after a large number of blocks are coded, the data stream is changed. If a CRC is attached to each block, an ACK / NACK signal must also be transferred for each data stream.

  In general, MCW can obtain a transfer rate higher than that of SCW. As a result, MCW is usually used despite the increase in ACK / NACK information transferred. However, in situations where the MCW transfers ACK / NACK signals for each data stream, the receiver must protect radio resources for multiple ACK / NACK transfers. The increase in control information reduces the radio resources for data transfer, resulting in a decrease in system efficiency.

  In the following, various aspects and embodiments of the present invention will be described. In general, these embodiments include an apparatus for transferring ACK / NACK signals in a MCW-type MIMO radio system. For example, the device can reduce the number of ACK / NACK signals transferred by maintaining a high transfer rate MCW.

  The uniform phase involves transferring ACK / NACK signals using multiple MCW-type transfer and receive antennas in a wireless communication system. Various operations generate multiple ACK / NACKs corresponding to multiple error detection codes inserted into multiple data streams received through multiple antennas, and combine these multiple ACK / NACKs. Generating an ACK / NACK and transferring the generated ACK / NACK through an antenna.

  Another aspect generates a number of ACKs / NACKs corresponding to a plurality of error detection codes inserted into a number of data streams received through a number of antennas, and groups the number of ACKs / NACKs. The method generates a single ACK / NACK per group by combining multiple grouped NACKs / NACKs into such multiple groups, and the generated ACK / NACK group is an antenna. Further comprising forwarding through.

  The uniform phase includes grouping multiple ACK / NACKs according to the form of the corresponding data stream in a grouping operation.

  Another aspect uses an error detection code such as a CRC code.

  Yet another aspect involves transferring a received data stream for one time slot through multiple transmit antennas.

  Yet another aspect involves combining multiple ACK / NACKs with an AND operation.

  In one embodiment, an apparatus for transferring ACK / NACK in a wireless communication system using a plurality of MCW-type transmission / reception antennas supports a plurality of error detection codes inserted in a number of data streams received through the plurality of antennas. An error checking unit that generates a number of ACK / NACKs. The apparatus includes a signal combining unit that generates one ACK / NACK by combining multiple ACK / NACKs, and a signal transfer unit that transfers ACK / NACK generated through the antenna.

  In another aspect, the apparatus is a control unit that groups multiple ACK / NACKs, a signal combining unit that generates one ACK / NACK per group by combining multiple grouped NACK / NACKs into multiple groups. And a signal transfer unit for transferring the generated ACK / NACK group through an antenna.

  According to a uniform phase, the control unit groups a number of ACK / NACK according to the form of the corresponding data stream.

  The uniform phase consists of an error detection code such as a CRC code, a received data stream transferred to one time slot through multiple transmit antennas, a signal combining unit that combines multiple ACK / NACK by AND operation, Is used.

  Referring again to FIG. 11, the receiving end includes multiple antennas. When independent data is transferred through multiple antennas to obtain a high transfer rate, the number of antennas at the receiving end must be greater than or equal to the number of antennas at the transmitting terminal. FIG. 11 is a diagram illustrating n antennas for representing reception of n information streams.

  Information received through a plurality of antennas (for example, n pieces of information in FIG. 11) is decoded corresponding to a channel coding technique performed by a transmitting end. Thereafter, the CRC check unit performs error check using the CRC included in each decoded information stream. If an error exists as a result of the CRC check, the CRC check unit generates a NACK. If there is no error, the CRC checking unit generates an ACK. Thus, when n different information streams are received in parallel, n ACK / NACKs are transferred. In this case, n received data streams may be data streams transferred to one time slot through n transmit antennas. Preferably, the information streams within a predetermined time slot can be processed simultaneously.

FIG. 11 is a diagram illustrating a state in which n ACK / NACKs are input to a combiner and combined into one ACK / NACK signal. For example, n ACK / NACKs can be combined into one ACK / NACK. An AND operation is performed so that these signals are combined into one ACK / NACK. In particular, n ACK / NACKs such as ACK / NACK1, ACK / NACK2,... ACK / NACKn are considered. The combined ACK / NACK can be expressed as:
(Combined) ACK / NACK = ACK / NACK1∩ACK / NACK2∩ ... ∩ACK / NACKn,
Here, when the data is successfully received, ACK / NACK1 to ACK / NACKn may each have a value of 1. Otherwise, each of these ACK / NACKs can have a value of zero.

  If the combined ACK / NACK indicates 1, it can be considered that a total of n data has been successfully received. If the combined ACK / NACK indicates 0, this indicates that at least one of the n data was not successfully received. As a result, frequency resources for control information transfer can be efficiently allocated.

  FIG. 12 is a block diagram illustrating an ACK / NACK transfer apparatus according to another embodiment of the present invention. In this embodiment, in addition to a number of couplers, a control unit is added to the configuration shown in FIG.

  In FIG. 12, each of the n ACKs / NACKs generated by the CRC check unit is input to the control unit. Thereafter, the control unit groups the input ACK / NACK into multiple groups. These groups can be classified according to the form of the received data stream. For example, if a predetermined portion of data is important for checking successful data reception and needs to be processed individually, it can be grouped individually. Alternatively, these ACK / NACKs may be divided into a predetermined number of groups so that the size of control information to be transferred can be appropriately selected regardless of the form of received data.

  As described above, grouped NACK / NACK signals are combined by multiple combiners to generate one ACK / NACK per group. Generally, ACK / NACK corresponding to a predetermined group includes one ACK / NACK. In this aspect, the corresponding ACK / NACK is processed in the same manner as other ACK / NACKs for which the combining operation is performed without performing the individual operation for combining the ACK / NACK signals.

  Further consider that the number of groups selected according to the above principle is less than or equal to m, so that m ACK / NACKs can be obtained. The m ACK / NACKs are input to the transmission unit and subsequently transferred through the antenna.

  In the embodiments of FIGS. 11 and 12, the error detection code executed using the CRC code has been described. However, the present invention is not limited to this, and an arbitrary error detection code, which is a signal requested by the receiving end, may be used to receive a notification as to whether or not the data transfer is successful.

  Various embodiments allow the receiving end to transfer ACK / NACK at the SCW level despite using MCW with a higher transfer rate than the SCW transfer rate. Optionally, when n data stream transfers are below a certain critical number, an ACK / NACK that indicates the success or failure of the transfer for each of the n data streams is replaced with a repetitive transfer of all n streams, Can be transferred without binding. Optionally, consider a situation where the transfer of predetermined data fails a predetermined number of times under the assumption that each of a number of received data streams can be partitioned. ACK / NACK information for indicating the success or failure of transfer of a predetermined data stream is transferred independently without combining, and the remaining ACK / NACK signals are combined and transferred.

  It can be seen that ACK / NACK is an example of control information notifying whether or not the data transferred from the transmitting end has been successfully received at the receiving end. ACK / NACK is usually used for HARQ. However, for example, any signal that performs the above function may be used instead of ACK / NACK.

Subcarrier Mapping in Uplink Various additional embodiments are associated with subcarrier mapping in the uplink. In particular, such an embodiment includes a method for allocating transmission data to frequency resources allocated to an uplink in a wireless communication system using a plurality of subcarriers, and a transmitter embodying the method.

  FIG. 13A is a diagram illustrating a localized allocation of multiple subcarriers. In the figure, regional allocation refers to transmission of user data through a predetermined number of subcarriers distributed adjacent to a certain band among the entire band of frequency resources allocated for uplink. User data is transferred only through a sub-carrier of a certain band by entering 0 in the remaining sub-carriers.

  With such regional allocation, only a part of the uplink frequency resource band is used. However, when the transfer data is transferred in units of resource units including a certain number of subcarriers, the transfer data is concentrated and arranged in a certain area in the resource unit allocated continuously to a part of the frequency resource band. Tend.

  FIG. 13B is a diagram illustrating a distributed allocation of multiple subcarriers. In the figure, distributed allocation refers to transmission of user data through subcarriers distributed at equal intervals over the entire band of frequency resources allocated for uplink. By entering 0 for the remaining subcarriers, the system transfers user data using only specific subcarriers that are distributed and assigned.

  Distributed allocation can distribute and transfer data over the entire bandwidth of uplink frequency resources for the purpose of increasing frequency diversity. Therefore, distributed allocation has the advantage of being strong against channel effects. However, when the pilot is transferred in a short block, the pilot interval becomes wider than when a long block is used, so that the channel estimation performance can be degraded.

  In general, the various embodiments include a method for allocating subcarriers for distributing and retransmitting data within an allocated partial band, and a transmitter to support this. Channel effects are minimized using regional allocation.

  The uniform phase includes a transmitter that supports and supports subcarriers that distribute and transfer data. A predetermined number of sub-carriers are arranged in a certain number and distributed by regional allocation.

  Another embodiment relates to a method for locating a subcarrier on the uplink when the subcarrier for data transfer is located on a frequency resource allocated for the uplink. One operation involves placing subcarriers for data transfer in the regional band of frequency resources allocated for the uplink, and these subcarriers are distributed at equal intervals in the entire portion of the regional band.

  According to one feature, the transfer data is a control signal coded repeatedly with predetermined bits.

  In other features, the transmitted data is transferred through N (N = 1, 2, 3,...) Resource units with a predetermined number of subcarriers, which are allocated for the uplink. The subcarriers are distributed at equal intervals over the entire band occupied by the N resource units.

  In another aspect, when a subcarrier for data transfer is allocated to a frequency resource allocated for the uplink, a method for allocating the subcarrier in the uplink is a frequency resource allocated for the uplink. Sub-carriers are grouped to transfer data by at least two sub-carriers over the entire bandwidth, and the grouped sub-carriers are distributed at equal intervals.

  Yet another feature relates to transfer data transferred through N (N = 1, 2, 3,...) Resource units with a predetermined number of subcarriers, where the subcarriers are up at regular intervals. The N resource units are arranged in a distributed manner over the entire band of frequency resources allocated for the link. The method further includes grouping the subcarriers into at least two subcarriers and placing the grouped subcarriers in each of the N resource units.

  In yet another aspect, an apparatus includes a subcarrier placement module that places subcarriers for data transfer in a regional band of frequency resources allocated for the uplink, the subcarriers comprising the entire regional band. The parts are distributed at equal intervals.

  In one feature, the transfer data is transferred through N (N = 1, 2, 3,...) Resource units with a predetermined number of subcarriers, where the subcarriers are frequency resources allocated for the uplink. N subbands are distributed at equal intervals over the entire band occupied by N resource units.

  In another aspect, a transfer apparatus that arranges subcarriers in the uplink groups the subcarriers for data transfer by at least two subcarriers across the entire band of frequency resources allocated for the uplink, and is grouped. The subcarriers are distributed at equal intervals.

  FIG. 14 is a block diagram illustrating a method of performing uplink transfer using OFDM. At block 210, a data stream having a high transfer rate is input serially and converted through a serial / parallel converter into a number of data streams having a low transfer rate. Each parallel-transformed data stream is multiplied by a corresponding subcarrier through a subcarrier mapper (block 220) and then converted to a time-domain signal by inverse discrete Fourier transform (IDFT) (block 230). At block 240, a cyclic prefix is inserted into the time domain signal to prevent channel interference. The signal is converted to a serial signal and then transferred to the receiving end (block 250).

  OFDMA is a system that performs modulation using a large number of orthogonal subcarriers, and refers to a multiple access method that provides multiple users by providing a part of usable subcarriers to different users. OFDMA provides different users with frequency resources such as subcarriers. Since frequency resources are independently provided to multiple users, they are not superimposed on each other.

  Since orthogonality is maintained between the subcarriers, a high transfer rate can be obtained. However, problems with peak-to-average power ratio (PAPR) arise. In order to effectively minimize this problem, spreading is performed in the frequency domain using a DFT matrix. This operation is typically performed before OFDM signal generation. The spreading result is modulated by OFDM to obtain a single carrier transfer. Such a case is referred to as DFT-S-OFDMA.

  FIG. 15 is a flowchart showing generation of a transfer signal by DFT-S-OFDMA. This technique is substantially the same as that shown in FIG. 1, and blocks 310 to 340 correspond to blocks 110 to 140 in FIG. However, the difference is that cyclic pre-insertion (block 350) occurs before parallel / serial conversion of block 360.

  In a multi-carrier system using OFDMA or DFT-S-OFDMA, terminal data, pilot, control information, etc. are transferred on the uplink. When terminal data is transferred on the uplink, the corresponding control information is transferred on the downlink. Using the corresponding control information, a transfer band is allocated or a data transfer format is determined.

  The pilot signal can be divided into two types. The CQ pilot is used to measure channel quality for performing terminal scheduling, adaptive modulation and coding. The data pilot is also used for channel estimation and data demodulation in data transfer. The data pilot is a pilot transferred to the corresponding area. As described above, the control information includes data-related control information and non-data-related control information. The terminal data, pilot, and control information can be transferred through a subframe having a predetermined structure. As an example, an FDD subframe for uplink proposed in 3GPP LTE is included. A suitable subframe is shown in FIG. 3A.

  Referring again to FIG. 3A, a cyclic prefix (CP) is inserted between each block to avoid inter-block interference. With this arrangement, a long block (LB) can be used to transfer uplink data or control information, and a short block (SB) can be used to transfer uplink data or pilot. .

  A first method of multiplexing subframes includes multiplexing terminal data, pilot, and demodulation information associated with data demodulation. The second multiplexing method includes multiplexing terminal data, pilot, and data related control information. A third multiplexing method includes multiplexing pilot and non-data related control information.

  Referring to FIG. 7 again, data related control information and non-data related control information for a specific user are multiplexed with the terminal data of the corresponding user, and at the same time, non-data related control information for other users is multiplexed together. Turn into. Thus, each resource block contains the same type of uplink data.

  Referring to FIG. 8 again, the data-related control information for the specific user and the terminal data are multiplexed, and the non-data-related control information for a number of users including the specific user has a fixed time-frequency. It is transferred through the area (hatched area in FIG. 8). As shown in FIG. 7 and FIG. 8, various data carried by subframes are multiplexed in the time domain and maintain the advantages of DFT-S-OFDM with low PAPR.

  Since terminal data and non-data related control information for a specific user are multiplexed and transferred in the same subframe, the same type of frequency allocation scheme may be applied to the terminal data and non-data related control information. It is normal. In particular, when region allocation is applied to terminal data, the region allocation method must also be applied to non-data related control information.

  As described above, ACK / NACK can be expressed by a relatively small number of bits. For example, the UE can repeatedly transmit ACK / NACK to improve the error rate. For example, this can be accomplished using the various techniques described above based on FIGS. 3A and 3B.

Note that the repeated ACK / NACK can be transmitted through a resource unit in which a predetermined number of consecutive subcarriers are collected. A resource unit typically includes 25 long block frequency intervals, but is not limited thereto. Optionally, the resource unit may include long block frequency intervals of different lengths (eg, 15, 12, 10, etc.). The normal resource unit size is expressed as follows:
RU = 25 * 15KHz (LB) = 375KHz
Accordingly, among the frequency allocation techniques described above, the regional allocation can be regarded as N resource units being continuously allocated to a partial band. Among the frequency allocation methods described above, the distributed allocation can be regarded as N resource units being discontinuously allocated at equal intervals over the entire band.

  In regional allocation, frequency resources allocated to subcarriers for ACK / NACK signal transmission are smaller than frequency resources occupied by N resources. As an example, FIG. 16 is a diagram illustrating a distribution of subcarriers used for resource unit and ACK / NACK transfer. In particular, N resource units are continuously allocated to a partial band of uplink frequency resources. Of the subcarriers included in the N resource units, the subcarriers used for repetitive ACK / NACK signal transfer are concentrated in a specific band (center band in FIG. 16) in the frequency resources occupied by the N resource units. Can be arranged. This case is called pure area allocation.

  As described above, the area allocation is weak to the influence of the channel because data is transferred through an adjacent channel. The pure area allocation is not only adjacent to N resource units, but also sub-carriers to be transferred included in the N resource units are concentrated in a specific band, and thus becomes more vulnerable to the influence of the channel.

  To remedy this vulnerability, improved regional allocation (distributed within allocated frequency resources) can be used. FIG. 17 is an example of subcarrier placement using improved regional allocation. These techniques apply regional allocation to N resource units, but apply distributed allocation to subcarriers to be transferred included in N resource units. In particular, the subcarriers actually used for ACK / NACK signal transfer are discontinuously arranged at equal intervals over the entire frequency resource.

  FIG. 18 is a diagram showing a distribution of subcarriers used for ACK / NACK signal transfer. Frequency diversity can be obtained using distributed allocation. When pilots are transferred in short blocks, the pilot interval is wider than when long blocks are used. Such an arrangement causes a decrease in channel estimation performance and is not preferable. An improved distributed allocation that can improve channel estimation performance can be obtained by grouping subcarriers for ACK / NACK signal transfer into multiple groups, each group including at least two subcarriers. Instead of arranging subcarriers individually, they are arranged as a group.

  19A and 19B arrange subcarriers using improved distributed allocation, but arrange two subcarriers as groups. In FIG. 19A, since each subcarrier transmits an ACK / NACK signal using a long block, a frequency interval (for example, 15 KHz) of only a long block exists between two subcarriers constituting the group. .

  In order to transfer an ACK / NACK signal to the receiving end, pilot information for matching synchronization between the transmitting and receiving ends must be transferred to the receiving end. Since pilot information does not need to be transferred to each subcarrier, in this embodiment, it is assumed that one pilot information is transferred to two grouped subcarriers. Pilot information is transferred through short blocks. Since the frequency band of a short block (for example, 30 KHz) is usually twice that of a long block, a technique of transferring one pilot information every two subcarriers for transferring an ACK / NACK signal Matches.

  FIG. 19B is a diagram illustrating frequency resource allocation of subcarriers for pilot information transfer. Considering the grouping of subcarriers for ACK / NACK signal transfer into three units, the frequency band occupied by one group (15 KHz * 3 = 45 KHz) is occupied by subcarriers for pilot transfer. Different from the frequency band (30 KHz). This requires a 30 KHz gap between these groups (FIG. 20A). As shown in FIG. 20B, since subcarriers for pilot information transfer must be arranged every 60 KHz, channel estimation performance using pilots is lower than when a group is composed of two subcarriers. End up.

  As described above, improved regional allocation or improved distributed allocation typically results in a suitable subcarrier mapper at the OFDMA transmission end (eg, block 330 of FIG. 15) or a subcarrier mapper at the OFDMA transmission end (eg, , Block 220) of FIG. Optionally, improved regional allocation or improved distributed allocation can be performed by a subcarrier allocation module responsible for each frequency resource allocation.

  The advantage of regional allocation allows efficient use of frequency resources and places subcarriers for transfer data in locally allocated resource units. Therefore, such an arrangement is protected from channel effects in a way that is larger than existing systems. Another advantage relates to distributed allocation to avoid channel effects. In this embodiment, a predetermined number of subcarriers are grouped and distributed for transfer. Therefore, the degradation of channel estimation is reduced compared to the conventional system.

  Each embodiment of the present invention is implemented using the exemplary series of operations described herein, but additional or fewer operations may be performed. Further, the order of operations illustrated and described is merely an example, and a single operation order is not required.

  The above examples and advantages are merely exemplary and are not intended to limit the invention. The present application can be easily applied to other forms of apparatuses and processors. The description of the present invention is intended to be illustrative and not limiting of the scope of the claims. Various alternatives, modifications, and changes will be apparent to those skilled in the art.

Claims (5)

A method for transferring an uplink acknowledgment in response to data transfer, comprising:
At the terminal, receiving a plurality of data blocks from the base station;
By generating a positive acknowledgment or a negative acknowledgment for each of the plurality of data blocks based on whether the decoding of each of the plurality of data blocks is successful, HARQ ( generating a hybrid automatic repeat request) acknowledgment information;
By encoding the HARQ acknowledgment information for the plurality of data blocks into a sequence of fixed length having a plurality of bits of a predetermined number, met by coupling the HARQ acknowledgment information for the plurality of data blocks Then, encoding the HARQ acknowledgment information for the plurality of data blocks includes encoding a plurality of response bits indicating whether the decoding of the plurality of data blocks is successful, Each of the bits is generated by performing a logical AND operation of individual HARQ acknowledgment information of a data block group in the plurality of data blocks ;
Transferring the fixed length sequence to the base station , wherein the plurality of response bits are mapped to the fixed length sequence . The method of claim 1, further comprising repeating the transfer of the fixed length sequence to the base station for a predetermined K times. A cyclic redundancy check (CRC) is attached to each of the plurality of data blocks,
The method of claim 1, wherein whether the decoding of each of the plurality of data blocks is successful is determined by examining the CRC of each of the plurality of data blocks.   The method of claim 1, wherein the plurality of data blocks are received sequentially or the plurality of data blocks are received in parallel. A terminal that transmits an uplink acknowledgment in response to data transfer,
A receiving module configured to receive a plurality of data blocks from a base station;
By generating a positive acknowledgment or a negative acknowledgment for each of the plurality of data blocks based on whether the decoding of each of the plurality of data blocks is successful, HARQ ( generating the hybrid automatic repeat request) and encoding the HARQ acknowledgment information for the plurality of data blocks into a fixed length sequence having a predetermined number of bits. and a processor configured to perform the method comprising: coupling the HARQ acknowledgment for the data block, to encode the HARQ acknowledgment information for the plurality of data blocks, said plurality of data Encoding a plurality of response bits indicating whether the decoding of the block is successful, each of the plurality of response bits being individual HARQ acknowledgment information of a data block group in the plurality of data blocks A processor generated by performing a logical AND operation of :
A transfer module configured to transfer the fixed-length sequence to the base station, the transfer module mapping the plurality of response bits to the fixed-length sequence. , Terminal.

Images