Method and apparatus for transmitting and receiving control information in an SC-FDMA system

The present invention relates to a mobile communication system, and more particularly to a method and an apparatus for transmitting and receiving control information.

In the field of mobile communication technology, the Orthogonal Frequency Division Multiple Access (hereinafter referred to as OFDMA) method or the Single Carrier-Frequency division Multiple connection (Single Carrier-Frequency division Multiple Access) similar to the OFDMA method. Access: Hereinafter referred to as "SC-FDMA") method is being actively studied as a method useful for transmitting high-speed data via a wireless channel. The 3rd Generation Partnership Project (hereinafter referred to as 3GPP), which is an organization of asynchronous cellular mobile communication standards, is a next-generation mobile communication system, Long Term Evolution (hereinafter referred to as 3GPP). We are studying the system as the basis of the multiple connection method.

In LTE systems, the uplink control information transmission format is classified according to the presence or absence of data transmission. The uplink control information includes acknowledgment (ACK) / negative acknowledgment (ACK) information, which is a response to downlink data transmission, and channel quality indication for feeding back the downlink channel state. : Hereinafter, it includes "CQI") information and multiple input multiple output (hereinafter referred to as "MIMO") information necessary for the operation of the multiple transmission / reception antenna.

When data and control information are transmitted simultaneously on the uplink or only data is transmitted, this data and control information are transmitted by time division multiplexing (hereinafter referred to as "TDM"). .. On the other hand, when only the control information is transmitted without data, the assigned specific frequency band is used to transmit the control information.

FIG. 1 is a diagram showing a configuration of control information when only control information in a 3GPP LTE system is transmitted by an applic. In FIG. 1, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The time domain has a range of one subframe 102 and the frequency domain has a range of transmission bandwidth 114.

Referring to FIG. 1, subframe 102, which is the basic transmission unit of the uplink, has a length of 1 ms, and each subframe contains two slots 104 and 106 having a length of 0.5 ms. Each of slots 104 and 106 contains a plurality of long blocks (hereinafter referred to as LB) 108, which are also referred to as long SC-FDMA symbols. Each of the slots shown in FIG. 1 contains seven LB108s.

In the frequency domain, the smallest transmission unit is the subcarrier, and the basic unit of resource allocation is the resource unit (Resource Unit: hereinafter referred to as RU) 110 or 112. RU110 or 112 includes a plurality of subcarriers and a plurality of LBs. In the configuration shown in FIG. 1, one RU contains 12 subcarriers and 14 LBs. In such a configuration, one RU can obtain frequency diversity by including not only a plurality of continuous subcarriers but also a plurality of discontinuous subcarriers having a constant interval between them. ..

Within one subframe 102, the control information is the 1st, 2nd, 3rd, 5th, 6th, 7th, 8th, 9th, 10th, 12th, 13th, and 14th LB. On the other hand, the pilot, which is also called the reference signal (hereinafter referred to as RS), is transmitted on each of the 4th and 11th LBs. This pilot is used for channel estimation for coherent demodulation on the receiving side because it contains a pre-promised sequence.

In an LTE system, when only control information is transmitted on the uplink, this control information is transmitted via a predefined frequency band for control information. In the present specification, such a type of transmission method is referred to as a "type A" transmission method. In the "type A" transmission method, the number of LBs for transmitting control information included in the control information frequency band and the number of LBs for transmitting RS can be changed depending on the case. Referring to FIG. 1, this control information frequency band corresponds to RU110 and 112 located at both ends of the system transmission band 114.

Generally, the frequency band for transmitting control information is composed of RU units, and a plurality of RUs are used for transmitting control information according to the number of terminals (UEs) to be multiplexed. Also, frequency hopping can be applied to increase frequency diversity between one subframe, in which case this frequency hopping can be performed slot by slot.

Referring to FIG. 1, control information # 1 is transmitted over the pre-allocated frequency band 110 in the first slot 104, frequency-hopping in the second slot 106, and then pre-allocated. Is transmitted via the frequency band 112 of. Although not shown, the control information # 2 is transmitted through the frequency band 112 in the first slot 104, frequency hopping in the second slot 106, and then transmitted through the frequency band 110.

The Code Division Multiplex (hereinafter referred to as "CDM") method is for multiplexing uplink control information including ACK / NACK information, CQI information, MIMO information, etc. between different users. Can be used for. This CDM method is more robust against interference signals than the Frequency Division Multiplex (hereinafter referred to as "FDM") method.

The Zadoff-Chu (ZC) sequence is discussed as the sequence used in the CDM method of control information. The Zadoff-Chu sequence has a good Peak to Average Power Ratio (hereinafter referred to as "PAPR") because the Zadoff-Chu sequence has a constant signal level in the time and frequency domain. However, it shows good channel estimation performance even in the frequency domain.

The Zadoff-Chu sequence has zero circular autocorrelation for non-zero shifts. Therefore, terminals (User Equipment: hereinafter referred to as UE) that use the same Zadoff-Chu sequence for transmitting control information are different from each other in the Zadoff-Chu sequence for identification between UEs. A time domain circular shift value can be given. This circular shift value maintains orthogonality between each user by being set differently according to the user so as to satisfy a condition larger than the maximum transmission delay value of the radio transmission path. Therefore, the number of users with multiple access is determined by the length of the Zadoff-Chu sequence and the circular shift value.

Hereinafter, in the type A transmission method, the mapping and transmission of the control information signal and the Zadoff-Chu sequence will be described with reference to FIG. A Zadoff-Chu sequence with a length N assigned to UEi is g_{(n + Δi) mod N}(n = 0, ..., N-1, Δ_iIndicates the time domain cyclic shift value for UEi, i indicates the UE index for identifying the UE), and the control information signal transmitted by UEi is m._{i, k}(k = 0, ..., N_LB, Here, N_LBMeans the number of LBs in a subframe), the signal C mapped to each LB_{i, k, n}(The nth sample of the kth LB of UEi) is defined by the following equation (1).

<maths num="1"><img file="JP5073763B2_D0001.tif" /></maths>

In the above equation (1), k = 0, ..., N_LB, N = 0, ..., N-1, where Δi indicates the time domain cyclic shift value of the Zadoff-Chu sequence for UEi.

In the configuration shown in FIG. 1, N showing the number of LBs in one subframe._LBIs 12, and the length N of the Zadoff-Chu sequence is 12, which is the same as the number of subcarriers contained in one RU. In FIG. 1, the UE index i is omitted. From the point of view of one UE, the time domain cyclically shifted Zadoff-Chu sequence is applied per LB, and the transmitted control information signal is a time domain cyclically shifted Zadoff with one modulation symbol per LB. -Consists of being multiplied by the Chu sequence. Therefore, up to N per subframe_LBA number of control information modulation symbols can be transmitted. That is, up to 12 control information modulation symbols can be transmitted during one subframe shown in FIG.

If all of the control information and data is transmitted, this data and this control information are time-division-multiplexed (TDM) and transmitted after being mapped to the time-frequency resource allotted for this data transmission. To. In the present specification, such a type of transmission method is referred to as a "type B" transmission method. Generally, the base station (Node B) schedules this time-frequency resource on a RU-by-RU basis. FIG. 2 shows the configuration of control information transmitted according to the Type B transmission method in a 3GPP LTE system. For system transmit bandwidth 208, one subframe 202 includes two slots 204 and 206 having a length of 1 ms and a length of 0.5 ms, respectively. Each slot contains 7 LB218s.

Referring to FIG. 2, within one subframe 202, control information and data are time-division-multiplexed, 1st, 2nd, 3rd, 5th, 6th, 7th, 8th, 9th, The 10th, 12th, 13th, and 14th LBs are transmitted, while the RS is transmitted in the 4th and 11th LBs, respectively. Also, within the transmit bandwidth 208, frequency bands 214 and 216 are allocated for the transmission of "type A" control information. Therefore, in frequency bands other than frequency bands 214 and 216, a "type B" scheme can be used for transmission of control information. UE # 1 transmits the control information and data in the frequency band 210 by time division multiplexing, and UE # 2 transmits the control information and data by time division multiplexing in the frequency band 212.

As described above, in transmitting the uplink control information, the UE applies the "type B" method or the "type A" method depending on whether or not there is uplink data to be transmitted together with the uplink control information. However, when the amount of control information to be transmitted is large, there may be a problem that resources for the time domain, the frequency domain, and the code domain are insufficient.

As described above, in transmitting the uplink control information, the UE applies the "type B" method or the "type A" method depending on whether or not there is uplink data to be transmitted together with the uplink control information. However, when the amount of control information to be transmitted is large, a problem of insufficient resources for the time domain, the frequency domain, and the code domain may occur.

The amount of control information varies according to the type of control information transmitted. CQI information for feeding back the downlink channel state will be described with an example. The CQI information includes a wideband CQI indicating the channel state of the entire system transmission band and a subband CQI indicating the channel state of a specific frequency band. The base station executes a scheduling operation to determine the resources allocated to the UE based on the CQI information fed back from the UE. Frequency selective scheduling requires subband CQI. The system transmission band includes a plurality of sub-bands, each of which has a size corresponding to a multiple of RU, which is the smallest unit of base station scheduling.

Considering the 10MHz transmission band, the LTE system can use a total of 50 RUs, each consisting of 12 subcarriers. If each subband contains two RUs, the LTE system contains a total of 25 subbands, so the UE feeds back 25 subbands CQI. In general, when considering signaling overhead, it is preferable to feed back CQI information about some of the subbands with the best channel state of all subbands. For example, assuming that the sub-band CQI is fed back to the three sub-bands with the best channel state among these 25 sub-bands, and each sub-band CQI is indicated by 5 bits, all sub-band CQI information. The total number of signaling bits required to feed back is calculated as follows. That is, 12 bits (= ceil {log) to indicate which subband is the CQI information.₂(₂₅C₃)}) And a total of 27 bits, including 15 bits (= 5 * 3) to indicate the channel state of each subband, are required to feed back all subband CQI information. Here, ceil {} means a sealing function.

From the viewpoint of scheduling, it is preferable to transmit the sub-band CQI information in the minimum transmission time unit with as little transmission delay as possible. Performing convolutional coding with a coding rate of 1/3 and applying 8 tail bits produces a coded stream containing 105 bits (= (27 + 8) x 3 bits). Subsequent Quadrature Phase Shift Keying (QPSK) modulation of this encoded stream produces 52.5 modulation symbols (= 105/2 modulation symbols).

In the case of the example shown in Figure 1, the amount of information transmitted (52.5 modulation symbols) is transmitted, considering that up to 12 modulation symbols can be transmitted in one subframe according to the Type A scheme. the amount of possible information (12 varying tone symbol) it is necessary to define a transmission scheme of greater than.

<p> Therefore, the present invention is proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method and an apparatus for transmitting a large amount of control information in a mobile communication system. is there.</p><p> Another object of the present invention is to provide a method and apparatus for allocating individual frequency bands for the transmission of a large amount of control information and increasing the transmission bit rate by spreading this control information in the time domain.</p>

<p> In order to achieve the above object, according to one aspect of the embodiment of the present invention, there is provided a method of transmitting control information in a single carrier frequency division multiplexing (SC-FDMA) system. The method has a step of generating the first control information to be transmitted and a different index in which the control information symbol including the first control information is assigned to each terminal (UE) by the base station. The step of spreading by an orthogonal code having a spreading index according to the information amount of the control information of 1 and the discrete Fourier transform (DFT) of the spread signal are executed, and the discrete Fourier transform signal is used as the first control information. A step of generating a frequency domain signal by mapping to a first frequency domain allocated for transmission, and a single carrier frequency domain multiplex connection of the frequency domain signal via an inverse fast Fourier transform (IFFT). After adding the step of mapping to the (SC-FDMA) symbol and the cyclic prefix (CP) to prevent interference between symbols to the SC-FDMA symbol, the signal to which the cyclic prefix is added is sent to the base station. It is characterized by including a step of transmitting.</p><p> According to another aspect of the embodiment of the present invention, there is provided a terminal (UE) device that transmits control information in a single carrier frequency division multiplexing (SC-FDMA) system. The device uses a quadrature code having a control information symbol including the first control information to be transmitted, having a different index assigned to each terminal by the base station, and having a diffusion index according to the amount of information of the first control information. The spreading control signal generator, the discrete Fourier transform block that performs the discrete Fourier transform (DFT) of the diffused signal, and the discrete Fourier transform signal are assigned for the transmission of the first control information. A mapping device that generates a frequency region signal by mapping to the first frequency region, and a single carrier frequency division multiple connection (SC-FDMA) symbol that converts the frequency region signal into a single carrier frequency division multiple connection (SC-FDMA) symbol via inverse fast Fourier transform (IFFT). After adding the inverse fast Fourier transform block to be mapped and the cyclic prefix (CP) to prevent interference between symbols to the SC-FDMA symbol, the signal with the cyclic prefix added is transmitted to the base station. It is characterized by including a click prefix inserter.</p><p> According to still another aspect of the embodiment of the present invention, there is provided a method of receiving control information in a single carrier frequency division multiplexing (SC-FDMA) system. The method involves extracting the SC-FDMA symbol by removing the cyclic prefix (CP) from the received signal to prevent inter-symbol interference, and the Fast Fourier Transform (FFT) of the SC-FDMA symbol. And the step of demapping the signal mapped to the first frequency region allocated for the transmission of the first control information from the fast Fourier transform signal, and the step of demapping the demapped signal. A step of converting into a time region signal via an inverse fast Fourier transform (IFFT), a step of extracting a control channel signal by demultiplexing the time region signal, and a step of extracting the control channel signal by a base station for each terminal. It is characterized by including a step of acquiring the first control information by back-spreading by an orthogonal code having a different index assigned and having a diffusion index according to the amount of information of the first control information. ..</p><p> According to still another aspect of the embodiment of the present invention, there is provided a base station apparatus for receiving control information in a single carrier frequency division multiple access (SC-FDMA) system. The device includes a cyclic prefix remover that extracts the SC-FDMA symbol from the received signal by removing the cyclic prefix (CP) to prevent inter-symbol interference, and a fast Fourier of the SC-FDMA symbol. Demapping the Fast Fourier Transform block that performs the transform (FFT) and the signal mapped from the Fast Fourier Transformed signal to the first frequency region allocated for the transmission of the first control information. A mapping device, an inverse fast Fourier transform block that converts the demapped signal into a time domain signal via an inverse fast Fourier transform (IFFT), and a control channel signal extracted by demultiplexing the time domain signal. By back-spreading the demultiplexer and the control channel signal with an orthogonal code having a different index assigned to each terminal by the base station and having a spread index according to the amount of information of the first control information. It is characterized by including a control channel signal receiver for acquiring the first control information.</p>

<p> The present invention provides a method and an apparatus for transmitting uplink control information in a next-generation mobile communication system. Specifically, when the amount of information of the control information is large, the transmission bit rate can be increased by spreading the control information with a quadrature code in the time domain, and identification between users can be made possible.</p>

<figref num="1">It is a figure which shows the structure of the control information when only the control information in a 3GPP LTE system is transmitted by an uprick.</figref><figref num="2">It is a figure which shows the structure of the control information transmitted according to the "type B" transmission system in a 3GPP LTE system.</figref><figref num="3">It is a figure which shows the transmission structure of the control information by a preferable embodiment of this invention.</figref><figref num="4">It is a flowchart which shows the operation process which generates the control information by the "type C" method by the preferable embodiment of this invention.</figref><figref num="5">It is a flowchart which shows the process which a UE transmits control information by a preferable embodiment of this invention.</figref><figref num="6A">It is a block diagram which shows the transmission device of UE which transmits the control information by the "type C" method by the preferable embodiment of this invention.</figref><figref num="6B">It is a block diagram which shows the transmission device of UE which transmits the control information by the "type C" method by the preferable embodiment of this invention.</figref><figref num="7">It is a flow diagram which shows the operation process which generates the control information for each user by a preferable embodiment of this invention.</figref><figref num="8A">It is a block diagram which shows the receiving device of the base station which receives the control information by the "type C" system by the preferable embodiment of this invention.</figref><figref num="8B">It is a block diagram which shows the receiving device of the base station which receives the control information by the "type C" system by the preferable embodiment of this invention.</figref>

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, for the purpose of clarifying only the gist of the present invention, specific description of related known functions or configurations will be omitted. Also, features defined in a detailed description of the invention, such as detailed configurations and elements of the invention, are provided to aid in a comprehensive understanding of embodiments of the invention. Therefore, it will be apparent to those skilled in the art that various modifications and variations of the embodiments described herein are possible without departing from the scope and gist of the present invention.

Specifically, in the SC-FDMA-based cellular communication system, the present specification describes the transmission / reception operation of the UE and the base station according to the present invention when the uplink control information is transmitted via a specific frequency region of the system band. ..

When the amount of control information to be transmitted is large, the "type A" method of transmitting only the control information without data via the uplink's pre-defined frequency band for control information is sufficient. It may happen that this control information cannot be transmitted within the time of. This control information includes ACK / NACK information, which is a response to downlink data, CQI information, which feeds back the downlink channel state, and Multiple Input Multiple Output (hereinafter referred to as MIMO, which is necessary for the operation of the multiple transmission / reception antenna. ) Contains information. In the present specification, for convenience of explanation, the control information transmission method proposed in the present invention is referred to as a "type C" method.

FIG. 3 is a diagram showing a control information transmission configuration according to a preferred embodiment of the present invention. For system transmit bandwidth 308, one subframe 302 contains two slots 304 and 306 having a length of 1 ms and 0.5 ms, respectively. Each slot 304 and 306 contains seven long blocks (hereinafter referred to as LB).

Hereinafter, a type C control information transmission method according to a preferred embodiment of the present invention will be described with reference to FIG. The frequency domain according to the "Type C" scheme operates separately from the frequency bands 310 and 312 allocated for the "Type A" scheme and the frequency bands 314 allocated for the "Type B" scheme. In the frequency domain of the "Type C" system, the basic unit of the transmission band is RU, and a plurality of RUs can be used for transmitting control information according to the "Type C" system.

In the transmission of control information according to the "Type A" or "Type C" scheme, frequency hopping can be performed slot by slot within a single subframe to increase frequency diversity gain. This slot-by-slot frequency hopping may be performed between the same type of frequency band, or between different types of frequency bands. This slot unit frequency hopping is predefined for system operation, which allows it to be commonly recognized by all UEs and base stations via signaling or system configuration.

According to the transmission configuration of frequency domains 316 and 318 allocated for the "Type C" scheme as shown in Figure 3, within one subframe 302, the control information is first, second, third, 5th. The 6th, 6th, 7th, 8th, 9th, 10th, 12th, 13th, and 14th LBs are transmitted, while RS is transmitted on the 4th and 11th LBs. The number of LBs for transmitting control information and the number of LBs for transmitting RS can be changed according to each case. Referring to FIG. 3, the frequency bands 310 and 312 allocated for the Type A scheme are located on the outermost side of the system transmit band 308 and are the frequency bands 316 and allocated for the Type C scheme. 318 is located inside the frequency bands 310 and 312 allocated for the "Type A" scheme. However, these positions are just an example and can be adjusted during system operation.

For example, the frequency bands 316 and 318 allocated for the "Type C" scheme are located on the outermost side of the system transmission band 308, and the frequency bands 310 and 312 allocated for the "Type A" scheme are ". It is located inside the frequency bands 316 and 318 allocated for the Type C "system. In the case of the other example, only the control information of the "type B" method and the "type C" method can be transmitted without using the "type A" method. In this case, the frequency bands 316 and 318 allocated for the "Type C" scheme are located on the outermost side of the system transmit band 308, and the frequency bands 314 allocated for the "Type B" scheme are the system. It is located at another position in the transmission band 308.

In the "Type A" scheme, one modulation symbol is represented by using a CDM scheme based on the ZC sequence to limit the amount of control information that can be transmitted within a subframe to have a small value. Mapped to each LB. In the "Type C" scheme, the ZC sequence is not used and the control information transmitted is in an orthogonal code such as the Walsh code or the Orthogonal Variable Spreading Factor (hereinafter referred to as "OVSF") code. After being spread, it is mapped to the LB to increase the amount of control information that can be transmitted within a single subframe.

For example, one RU containing 12 subcarriers has a Walsh-Hadamard code assigned to the "Type C" frequency domains 316 and 318 and having a Spreading Factor (hereinafter referred to as "SF") 4. By use, 3 (ie 12/4) control information modulation symbols can be transmitted during one subframe. When this control information is modulated according to the QPSK method and encoded with an error correction code having a coding rate of 1/3, the 36 modulation symbols become 24 (ie, 36 × 2/3) information bits. Will be converted. Under the same conditions, 12 modulated symbols can be transmitted during one subframe according to the "Type A" scheme. Therefore, the "type C" method can transmit 3 (ie, 36/12) times more control information than the control information that can be transmitted by the "type A" method.

Each modulation symbol of this control information is m_i(Here, i indicates the LB index, i = 1, ..., N_LBAnd N_LBMeans the number of LBs used to transmit control information in one subframe), and according to the diffusion index (SF) used to transmit this control information, the control information transmitted by each LB Modulation symbols are defined as follows: 1st LB: m₁, ..., m_{NLB / SF} Second LB: m_{NLB / SF + 1}, ..., m_{2 * NLB / SF} ... kth LB: m_{(k-1) * NLB / SF + 1}, ..., m_{k * NLB / SF} ... N_LBSecond LB: m_{(NLB-1) * NLB / SF + 1}, ..., m_{NLB * NLB / SF}

The walsh-Hadamard property allows the control signals of up to SF UEs to be multiplexed using the same time-frequency resources. The RS signal of each UE is obtained by using the ZC sequence for the RS signal required for channel estimation of each UE and applying different time domain cyclic shift values of the ZC sequence to each UE. Can be identified.

In the present specification, it is described that the control information frequency band for the type A transmission configuration and the control information frequency band for the type C transmission configuration are operated separately. However, in a modified embodiment, the "type A" or "type C" transmission configuration is selectively used for this control information frequency band, or "type C" for this control information frequency band. It is also possible to use only one control information frequency band while using only the transmission configuration. In the former case, the choice between "type A" and "type C" can be made based on the amount of control information transmitted as described below.

FIG. 4 is a flow chart showing an operation process for generating control information by the type C method according to a preferred embodiment of the present invention.

In the operating process shown in Figure 4, a total of 12 LBs are used to transmit control information during one subframe, one RU containing 12 subcarriers is used in the frequency domain, and SF = Walsh-Hadamard with 4 (o_4,j, Where j = 1, 2, 3, or 4, where j means the index of each walsh-Hadamard with SF = 4, and different walsh-Hadamard indexes j are assigned to different UEs). Corresponds to the process of generating a control channel signal that maps to a single LB, based on the assumption that it will be used.

In step 402, the UE performs error correction coding and modulation of the transmitted control information to perform the modulation symbol (m).₁, M₂, M₃, ... including) is generated. Since SF = 4, each modulation symbol is spread over 4 chips. Therefore, the three modulation symbols are spread by a quadrature code with SF = 4 in step 404, for a total of 12 chips (m).₁ O_4,j(1), m₁ O_4,j(2), m₁ O_4,j(3), m₁ O_4,j(4), m₂ O_4,j(1), m₂ O_4,j(2), m₂ O_4,j(3), m₂ O_4,j(4), m₃ O_4,j(1), m₃ O_4,j(2), m₃ O_4,j(3), and m₃ O_4,j(4)) is generated. Where o_4,j(i) indicates the i-th chip of the j-th code among the orthogonal codes having SF = 4.

To randomize cell-to-cell interference, the diffused signal containing the 12 chips can be scrambled in step 406 according to different scrambling sequences from cell to cell. Scramble sequence_{k, n}Is defined as. Here, k indicates the length of the scrambling sequence, and n indicates the tip index of the scrambling sequence. This scrambling sequence is multiplied by this diffused signal on a chip-by-chip basis. At this time, the length of this scrambling sequence may be the same as the length of the subframe, or may be the same as the frame length of 10 ms.

The diffused and scrambled signal as described above contains a total of 12 samples for each LB, and in step 408, 12 via the Discrete Fourier Transform (DFT). After being converted into a frequency region signal containing the sample of, in step 410, it is mapped by the subcarrier mapper to the frequency region pre-allocated for "type C" type control information transmission. Then, in step 412, this frequency domain signal is transformed into a time domain signal via an Inverse Fast Fourier Transform (hereinafter referred to as IFFT). After a cyclic prefix (Cyclic Prefix: hereinafter referred to as CP) for preventing intersymbol interference is added to the time domain signal 414, the signal to which CP is added is the signal to which CP is added. It is transmitted after performing radio frequency (hereinafter referred to as "RF") processing.

In order to enable the transmission of "Type C" type control information as described above, the base station uses information about the frequency domain allocated for transmission of "Type C" type control information, used by each UE. Notify the UE of the transmission cycle of the orthogonal code information and the control information of the "type C" method. For example, if the UE sends subband CQI information for each subframe, the overhead burden is too great. Therefore, the UE can sparsely transmit subband CQI information at regular intervals. As a result, the base station can adjust the transmission cycle and the transmission timing for each UE so that a plurality of UEs share and use the limited time-frequency-code resource. This information may be notified to the UE by the base station via higher layer signaling, or may be dynamically notified via physical layer signaling.

FIG. 5 is a flow chart showing a process in which the UE transmits control information according to a preferred embodiment of the present invention.

Referring to FIG. 5, in step 502, the UE receives various prior information related to the uplink control information from the base station before starting the transmission of the control information, and appropriately indicates the occurrence of the transmitted control information. Prepare to generate a good signal. This prior information includes frequency domain information for transmitting "type A" control information, ZC sequence information, circular shift value of ZC sequence for each UE, and frequency domain for transmitting "type C" control information. Information, transmission cycle and transmission timing for each type of control information, orthogonal code information for each UE, and the like can be included.

In step 504, the UE determines the transmission method of this control information. An example of this criterion is as follows. The UE selects the "Type A" method when there is no uplink data to be transmitted and the amount of information in this control information is less than or equal to a predefined threshold. If this control information and data to be transmitted is present on the uplink, the UE chooses a "type B" scheme. Finally, if there is no uplink data to be transmitted and the amount of information in this control information exceeds this predefined threshold or various control information is transmitted at the same time, the UE will say "Type C". "Select a method.

If the UE selects the "Type A" method as a result of the determination in step 504, the UE generates this control information in step 506 and sequentially performs channel coding, rate matching, and modulation of this control information. By executing, the control information modulation symbol is generated. This rate matching means puncturing or repeating the bits encoded so that the number of encoded bits matches the number of bits that can be transmitted over the physical channel. Then, in step 508, the UE applies a circular shift to the ZC sequence pre-assigned by the base station, multiplies this control information modulation symbol by this circularly shifted ZC sequence by LB, and then performs this multiplication. A control channel signal is generated by mapping the product to the corresponding LB.

In step 518, the generated control channel signal is scrambled to generate a scrambled time domain signal in order to randomize cell-to-cell interference. At step 520, the UE performs a DFT of this scrambled time domain signal, and the subcarriers map this scrambled time domain signal to a pre-assigned frequency domain to cause the frequency domain signal. To generate. In step 522, the UE generates an SC-FDMA signal by converting this frequency domain signal into a time domain signal via IFFT and then adding CP to this time domain signal. After that, the SC-FDMA signal is transmitted to the base station after undergoing RF signal processing.

If the UE selects the "Type B" method as a result of this determination in step 504, the UE generates this control information in step 510 and sequentially performs channel coding, rate matching, and modulation of this control information. By executing in, the control information modulation symbol is generated. At step 512, the UE multiplexes this generated control information modulation symbol with the transmitted data modulation symbol. The multiplexed signal is then processed through steps 518 through 522 and then transmitted to the base station. This multiplexed signal, which contains data and control information multiplexed according to the "Type B" scheme, is mapped to a time-frequency resource scheduled by the base station after undergoing a DFT and IFFT.

If the UE selects the "Type C" method as a result of this determination in step 504, the UE generates this control information in step 514 and sequentially performs channel coding, rate matching, and modulation of this control information. By executing in, the control information modulation symbol is generated. At step 516, the UE generates a control channel signal by spreading this generated control information modulation symbol using the assigned quadrature code. After this, the control channel signal generated from this diffused control information modulation symbol is processed through steps 518 to 522 and then transmitted to the base station. At this time, this control channel signal generated by the "type C" method is mapped to the frequency band allocated for the "type C" method.

On the other hand, the scrambling operation in step 518 may be performed before the rate-matched signals in each of step 506, step 510, and step 514 are modulated. As mentioned above, the pre-modulation scrambling operation can also randomize cell-to-cell interference. This also applies to the following embodiments.

Hereinafter, the main operating principle of the present invention will be described with reference to specific embodiments.

First Embodiment 6A and 6B are block diagrams showing a UE transmitter that transmits control information in a "type C" fashion according to a preferred embodiment of the present invention.

Referring to FIG. 6A, the transmitters include control unit 610, downlink control information receiver unit 611, RS generator 612, control signal generator 614, multiplexing device 617, series / parallel converter (S / P) 618, Includes DFT block 619, mapping device 620, IFFT block 622, parallel / series converter (P / S) 624, CP inserter 630, and antenna 632. In FIG. 6A, the elements related to the transmission of uplink data are omitted.

The UE receives advance information related to transmission of uplink control information from the base station via the downlink control information receiver 611 so as to generate an appropriate signal indicating that the transmitted control information is generated. This prior information is applied to the control unit 610. This prior information includes frequency domain information for transmission of this control information, ZC sequence information for RS transmission, cyclic shift value of ZC sequence for each UE, transmission cycle and transmission timing for each control information type, and so on. Includes walsh-Hadamard information for each UE.

The control unit 610 controls the overall operation of the transmitter and is required by major blocks such as the multiplexing device 617, the DFT block 619, the mapping device 620, the RS generator 612, and the control signal generator 614. Send information. The prior information input to the RS generator 612 includes ZC sequence information and time domain cyclic shift information assigned to the UE. The prior information input to the control signal generator 614 related to the transmission of uplink control information includes frequency domain information for transmission of this control information, ZC sequence information for RS transmission, and ZC sequence for each UE. Includes the cyclic shift value of, the transmission cycle and transmission timing for each control information type, and the orthogonal code information for each UE.

The multiplexing device 617 receives the timing information regarding the control information and the RS from the control unit 610, and outputs the RS signal and the control signal generated at the LB position defined in advance by the RS generator 612 and the control signal generator 614. Select and output each. To this end, the mapping device 620 for mapping this signal to the actual frequency resource receives frequency allocation information from the controller 610.

The output signal of the multiplexing device 617 is converted into a parallel signal by the S / P converter 618, and then the converted parallel signal is input to the DFT block 619. The input / output size of the DFT block 619 is variable according to the amount of control information input from the controller 610, and the output of the DFT block 619 is a frequency resource in this control information frequency domain after being input to the mapping device 620. Mapped to. The output of the mapping device 620 is converted into a time domain signal by the IFFT block 622 and then converted into a series signal by the P / S converter 624. The CP for preventing intersymbol interference is then added to this series signal by the CP inserter 630 and then transmitted via the antenna 632.

FIG. 6B is a block diagram showing the control signal generator 614 according to the preferred embodiment of the present invention in more detail.

Referring to FIG. 6B, the control information is generated according to the format of the control information transmitted by the control information generator 640. For example, when subband CQI information is transmitted, the control information indicating this subband CQI information is defined in advance as to how to transmit CQI information regarding any subband among all subbands. Constructed according to format. The encoder 642 provides error correction capability by channel coding this control information. The channel coding method or coding rate is determined according to the type of this control information. The rate matching block 644 punctures or iterates over this channel-coded bit string according to the number of physical channel bits. The modulator 646 generates a modulation symbol by modulating the output bit string of the rate matching block 644. This generated modulation symbol is diffused by the diffuser 648 via an operation with a Walsh-Hadamard code having a diffusion index assigned by the base station. This diffused signal can be additionally scrambled by the scrambler 650 to randomize the amount of inter-cell interference. As mentioned above, the scrambler 650 can be located at the front end of the modulator 646.

The control information of each UE can be identified through this spreading operation. Further, the transmission bit rate of this control information can be adjusted by changing the SF of the orthogonal code. For example, if one RU is assigned to transmit this control information and the RU contains 12 subcarriers, then 3 in one LB (ie 12/4) using a quadrature symbol with SF = 4. ) Modulation symbols can be transmitted. If this control information is transmitted over 12 LBs in one subframe, a total of 36 control information modulation symbols can be transmitted, which is a symbol rate of 36 kbps (per second). Corresponds to the symbol). Therefore, as described above, when the amount of control information transmitted varies according to the type of control information, the transmission rate of this control information transmitted can be adjusted by adjusting the SF.

FIG. 7 is a flow chart showing an operation process for generating control information for each user according to a preferred embodiment of the present invention.

Referring to FIG. 7, UE # 1 700 and UE # 2 701 use one RU corresponding to the same time-frequency resource in transmitting control information according to the Type C method. In addition, UE # 1 700, which has a relatively small amount of control information to be transmitted, has a Walsh-Hadamard code o with SF = 4._4,1UE # 2 701, which uses a relatively large amount of control information to be transmitted, has a Walsh-Hadamard code o with SF = 2._2,2To use. Where o_{i, j}Means the jth orthogonal code among the orthogonal codes having a length of i, and each orthogonal code contains m chips. A typical example of this Walsh-Hadamard code includes an OVSF code used in a Wideband Code Division Multiple Access (hereinafter referred to as WCDMA) system.

Since UE # 1 700 and UE # 2 701 all use 12 subcarriers per LB, the maximum number of control information samples (or chips) that can be mapped per LB is 12.

In the case of UE # 1 700, each modulation symbol is spread over 4 chips by a quadrature code with SF = 4. Since one LB contains up to 12 chips, it is possible to map up to 3 (ie 12/4) modulation symbols per LB. That is, in the case of UE # 1 700, in step 702, the control information modulation symbol is mapped to each LB in units of three symbols. Then, in step 704, each modulation symbol (m)₁, M₂, M₃, ... are included) are diffused by Walsh-Hadamard with SF = 4, resulting in a total of 12 chips (m).₁ O_4,1(1), m₁ O_4,1(2), m₁ O_4,1(3), m₁ O_4,1(4), m₂ O_4,1(1), m₂ O_4,1(2), m₂ O_4,1(3), m₂ O_4,1(4), m₃ O_4,1(1), m₃ O_4,1(2), m₃ O_4,1(3), and m₃ O_4,1(4)) is generated. Where o_4,1(i) indicates the i-th chip of the first code among the orthogonal codes having SF = 4.

To randomize cell-to-cell interference, this diffused signal containing 12 chips can be scrambled in step 706 according to different scrambling sequences from cell to cell. Scramble sequence_{k, n}Defined in. Here, k indicates the length of the scrambling sequence, and n indicates the tip index of the scrambling sequence. This scrambling sequence is multiplied by this diffused signal on a chip-by-chip basis. At this time, the length of this scrambling sequence may be the same as the length of the subframe, or may be the same as the frame length of 10 ms. The scrambled control channel signal generated as described above is converted into an SC-FDMA signal after being applied to the DFT block.

In the case of UE # 2 701, each modulation symbol is spread over two chips by a quadrature code with SF = 2. Since one LB contains up to 12 chips, up to 6 (ie 12/2) modulation symbols can be mapped per LB. That is, in the case of UE # 2 701, in step 708, the control information modulation symbols are mapped to each LB in units of 6 symbols. Then, in step 710, each modulation symbol (m)₁, M₂, M₃, M₄, M₅, M₆, ... are included) are diffused by Walsh-Hadamard with SF = 2 for a total of 12 chips (m)₁ O_2,2(1), m₁ O_2,2(2), m₂ O_2,2(1), m₂ O_2,2(2), m₃ O_2,2(1), m₃ O_2,2(2), m₄ O_2,2(1), m₄ O_2,2(2), m₅ O_2,2(1), m₅ O_2,2(2), m₆ O_2,2(1), and m₆ O_2,2(2)) is generated.

To randomize cell-to-cell interference, as in UE # 1 700, this diffused signal containing 12 chips can be scrambled in step 712 by different scrambling sequences from cell to cell. .. S scrambling sequence_{k, n}Defined in. Here, k indicates the length of the scrambling sequence, and n indicates the tip index of the scrambling sequence. This scrambling sequence is multiplied by this diffused signal on a chip-by-chip basis. The control channel signal generated and scrambled as described above is applied to the DFT block and then converted into an SC-FDMA signal.

8A and 8B are block diagrams showing a base station receiver that receives control information in a "type C" fashion according to a preferred embodiment of the present invention.

Referring to FIG. 8A, the receivers are antenna 810, CP remover 812, S / P converter 814, FFT block 816, demapping device 818, IFFT block 810, P / S converter 822, demultiplexer 824. , Control unit 826, control signal receiver 828, and channel estimator 830. In FIG. 8, elements related to transmission / reception of uplink data are omitted.

Control 826 controls the overall operation of the receiver and is required by major blocks such as demultiplexer 824, IFFT block 820, demapping device 818, control signal receiver 828, and channel estimator 830. Provide prior information. Various prior information related to the uplink control information input to the control signal receiver 828 includes various parameters necessary for decoding each UE-specific control information and each UE-specific orthogonal code information. The prior information input to the channel estimator 830 can include ZC sequence information and time domain cyclic shift information assigned to the received UE.

In order to classify the control channel signal and RS signal input to the control signal receiver 828 and the channel estimator 830, the demultiplexer 824 receives timing information regarding the control channel signal and RS signal from the control unit 826. .. At this time, the demapping device 818 that extracts this signal from the actual frequency resource receives frequency allocation information and the like from the control unit 826.

The base station receives a radio signal including uplink control information from the UE via the antenna 810. The CP remover 812 then removes the CP from this radio signal, and the S / P converter 814 converts the CP removed signal into a parallel signal and inputs this parallel signal to the FFT block 816. After that, the FFT signal output from the FFT block 816 is demapped by the demapping device 818 and converted into a time domain signal by the IFFT block 820. The input / output size of the IFFT block 820 is variable according to the amount of control information input from the control unit 826. The output of the IFFT block 820 is converted into a series signal by the P / S converter 822 and separated into a control channel signal and an RS signal by the demultiplexer 824. The control channel signal and the RS signal are input to the control signal receiver 828 and the channel estimator 830, respectively. The channel estimator 830 acquires a channel estimate from the RS signal and provides this acquired value to the control signal receiver 828 for channel compensation of the control channel signal. The control signal receiver 828 acquires the control information transmitted by the UE from the channel-compensated control signal after performing channel compensation of the control channel signal using this channel estimate.

FIG. 8B is a block diagram showing the control signal receiver 828 according to the present invention more specifically.

Referring to FIG. 8B, the descrambler 831 performs a descramble operation of the control signal provided by the demultiplexer 824 using a pre-promised scrambling code between the UE and the base station. The despreader 832 removes the signals of other UEs by despreading this descrambled signal using a quadrature code with a spread exponent assigned to the UE that needs to obtain this control information. Then, the signal including the control information to be acquired is extracted. The demodulator 834 demodulates the output of the despreader 832, and the delate matching block 836 produces a fully coded bit string by iterating or puncturing the output of the demodulator 834. The decoder 838 also performs channel decoding of this coded bit string. The control information analyzer 840 analyzes the meaning of this control information from this decoded bit string. For example, when this control information is CQI information, the control information analyzer 840 can recognize what sub-band is related to this control information and the channel state of the sub-band.

Although the present invention has been described in detail with reference to specific embodiments, it is clear to those skilled in the art that various modifications can be made without departing from the scope and gist of the present invention. The scope of the present invention should not be limited to the above-described embodiments, but should be defined within the scope of the claims and equivalents.

302 subframe 304 slots, 308 Transmit Bandwidth 310, 312 Reverse resource for type A 314 Reverse resource for type B Reverse resource for 316, 318 type C