WO2019187146A1

WO2019187146A1 - Base station, radio communication terminal, radio communication system, and radio communication method

Info

Publication number: WO2019187146A1
Application number: PCT/JP2018/013958
Authority: WO
Inventors: 三夫小林; 義博河▲崎▼
Original assignee: 富士通株式会社
Priority date: 2018-03-30
Filing date: 2018-03-30
Publication date: 2019-10-03
Also published as: JPWO2019187146A1; JP6947291B2

Abstract

The base station (100) has a PDSCH/MCS control unit (110), an ACK reception MCS-ACK index determination unit (112), and a radio reception unit (102). The PDSCH/MCS control unit (110) determines a coding and modulation scheme for a signal to be transmitted to a radio communication terminal. The ACK reception MCS-ACK index determination unit (112) determines resources to be used in the transmission of a response signal to the aforementioned signal by reference to association information associating such resources to the coding and modulation scheme applied to the aforementioned signal. The radio reception unit (102) receives the aforementioned response signal transmitted using the aforementioned resources.

Description

Base station, radio communication terminal, radio communication system, and radio communication method

The present invention relates to a base station, a wireless communication terminal, a wireless communication system, and a wireless communication method.

In recent years, as a next-generation wireless communication system with higher speed and higher reliability, development of a fifth-generation mobile communication system is in progress. Requirements for the fifth generation mobile communication system include, for example, broadband wireless service (eMBB: enhanced Mobile Broad Band), ultra-reliable and low latency communications (URLLC), and communication with a large number of machine terminals. (MMTC: massive Machine Type Communications). Among these technologies, URLLC is expected to be applied to automatic operation, telemedicine, industrial equipment, IoT (Internet of Things), etc. by realizing not only low delay but also highly reliable wireless communication.

In order to achieve high reliability in URLLC, for example, a technique of increasing the transmission power to increase the SNR (Signal to Noise Ratio), a technique of improving the SNR tolerance by adaptive modulation coding (AMC), and A method of performing retransmission control using HARQ (Hybrid Automatic Repeat reQuest) is conceivable. Among these methods, AMC is defined as an MCS (Modulation and Coding Scheme) table in LTE (Long Term Evolution) standard specifications (3Gpp TS36.213).

In the MCS table, the Modulation Order (modulation multi-level number) and TBS (Transport Block Size) index (data size index) for the MCS index are uniquely defined, and the base station selects the MCS index according to the radio propagation status. Thus, adaptive modulation coding is performed. For example, the base station selects a small MCS index when the radio wave condition is poor and the SNR is low, and selects a large MCS index when the SNR is high. In URLLC, in order to make wireless communication highly reliable even in an SNR lower than LTE, it is considered to introduce an MCS index having a lower SNR than in the past.

In a system to which HARQ is applied, the communication quality of an ACK (Acknowledge) signal for notifying a transmission side (for example, a base station) from a reception side (for example, a wireless communication terminal) that communication is successful has an important meaning. This is because if the downlink communication (main signal communication) succeeds but the reception of the uplink ACK signal fails, the transmitting side determines that the downlink communication has failed and performs retransmission. This is because the throughput is reduced. Here, if the obtained throughput is T, the maximum throughput in a certain MCS is T _{max_mcs} , the block error rate of the main signal is BLER, and the error rate of the ACK signal with respect to the main signal is ACK _BER , T can be expressed by the following equation: .

T = T _{max_mcs} × (1− (BLER + ACK _BER ))

As described above, when communication is performed with a low SNR in URLLC, there is a high possibility that not only the transmission of the main signal but also the return of the ACK signal will fail. As a technique for improving the communication quality of the ACK signal, for example, it is conceivable to increase the transmission power and increase the occupied resources. However, a fixed increase in resources may cause new problems such as a limit in transmission power or a decrease in system efficiency accompanying an increase in resources.

The disclosed technique has been made in view of the above, and is capable of suppressing non-delivery of an ACK signal while maintaining resource utilization efficiency, a base station, a wireless communication terminal, a wireless communication system, and a wireless communication method The purpose is to provide.

In order to solve the above-described problem and achieve the object, the base station disclosed in the present application includes, in one aspect, a first determination unit, a second determination unit, and a reception unit. The first determination unit determines a coding and modulation scheme of a signal to be transmitted to the wireless communication terminal. The second determination unit refers to association information between an encoding and modulation scheme applied to the signal and a resource used for transmission of a response signal to the signal, and determines the resource. The receiving unit receives the response signal transmitted using the resource.

According to one aspect of the base station disclosed in the present application, it is possible to suppress non-delivery of the ACK signal while maintaining resource utilization efficiency.

FIG. 1 is a diagram illustrating the configuration of the base station according to the first embodiment. FIG. 2 is a diagram illustrating an example of data storage in the LUT according to the first embodiment. FIG. 3 is a diagram illustrating that the uplink transmission resource for ACK return is a variable size in the PUCCH. FIG. 4 is a diagram showing that the uplink transmission resource for ACK reply has a variable size in PUSCH. FIG. 5 is a diagram illustrating the configuration of the wireless communication terminal according to the first embodiment. FIG. 6 is a diagram for explaining the operation of the wireless communication system. FIG. 7 is a diagram illustrating an example of signaling when an LUT including an ACK index definition is individually set for each wireless communication terminal. FIG. 8 is a diagram for explaining resource allocation by the control signal modulation unit of the base station according to the first embodiment. FIG. 9 is a diagram for explaining resource allocation by the main signal modulation unit of the base station according to the first embodiment. FIG. 10 is a diagram for explaining variables used in the equations (5) and (6). FIG. 11 is a diagram illustrating an example of data storage in the LUT according to the second embodiment when 256QAM is not applied. FIG. 12 is a diagram illustrating a data storage example of the LUT according to the second embodiment when 256QAM is applied. FIG. 13 is a diagram for explaining resource allocation by the control signal modulation unit of the base station according to the second embodiment. FIG. 14 is a diagram for explaining resource allocation by the main signal modulation unit of the base station according to the second embodiment. FIG. 15 is a diagram for explaining variables used in Expression (8) and Expression (9).

Hereinafter, embodiments of a base station, a wireless communication terminal, a wireless communication system, and a wireless communication method disclosed in the present application will be described in detail with reference to the drawings. The base station, wireless communication terminal, wireless communication system, and wireless communication method disclosed in the present application are not limited by the description of the following embodiments.

First, Example 1 will be described. FIG. 1 is a diagram illustrating the configuration of the base station 100 according to the first embodiment. As shown in FIG. 1, the base station 100 includes a reception antenna unit 101, a radio reception unit 102, a PUCCH / PUSCH demodulation / decoding unit 103, an AN determination unit 104, a HARQ control buffer unit 105, an encoding unit 106, and a modulation unit 107. A wireless transmission unit 108 and a transmission antenna unit 109 are included. Furthermore, the base station 100 includes a PDSCH / MCS control unit 110, an LUT (LookUp Table) 111, an ACK reception MCS-ACK index determination unit 112, and an HARQ process (m) MCS storage unit 113. Each of these components is connected so that signals and data can be input and output in one direction or in both directions.

The receiving antenna unit 101 receives an uplink radio signal. The wireless reception unit 102 performs frequency conversion and A / D (Analog to Digital) conversion. The PUCCH / PUSCH demodulation / decoding unit 103 refers to the resource information determined by the ACK reception MCS-ACK index determination unit 112 and performs demodulation and decoding according to the LTE uplink physical channel specification. The AN determination unit 104 determines whether the demodulation / decoding result of PUCCH (Physical Uplink Control CHannel) or PUSCH (Physical Uplink Shared CHannel) is ACK or NACK. The HARQ control buffer unit 105 performs retransmission control using HARQ. The encoding unit 106 includes a control signal encoding unit 106a and a main signal encoding unit 106b, and encodes PDCCH (Physical Downlink Control Channel) and PDSCH (Physical Downlink Shared Channel) for each signal. . The modulation unit 107 includes a control signal modulation unit 107a and a main signal modulation unit 107b, and performs PDCCH and PDSCH modulation and resource allocation for each signal. The wireless transmission unit 108 performs D / A (Digital to Analog) conversion and frequency conversion. The transmission antenna unit 109 transmits a downlink radio signal.

The PDSCH / MCS control unit 110, depending on the CQI (Channel Quality Indicator) reported from the radio communication terminal 200, the downlink data size, and the coding and modulation scheme (DL-MCS: Down Link-Modulation and) Determine Coding Scheme. The determined DL-MCS is transmitted to the radio communication terminal 200 as a part of DCI (Downlink Control Information) by the PDCCH encoded by the control signal encoding unit 106a.

An LUT (LookUp Table) 111 is a common MCS table that is predetermined between the base station 100 and the radio communication terminal 200, and is referred to when the ACK reception MCS-ACK index determination unit 112 determines resource allocation information. The FIG. 2 is a diagram illustrating a data storage example of the LUT 111 according to the first embodiment. As shown in FIG. 2, taking the main signal MCS table in the LTE system as an example, ACKindex is defined in addition to MCSindex, Modulation Order, and TBSindex. This makes it possible to determine the ACK index according to the downlink main signal MCS.

FIG. 3 is a diagram showing that the uplink transmission resource for ACK return is a variable size in the PUCCH. FIG. 4 is a diagram showing that the uplink transmission resource for ACK reply has a variable size in PUSCH. 3 and 4, time is defined on the x-axis and frequency is defined on the y-axis. In the uplink channel in LTE, when there is no UL-Grant (PUSCH), the radio communication terminal 200 returns an ACK signal using resources on the PUCCH (for example, PUCCH # 1), but UL-Grant (PUSCH). ), An ACK signal is returned using resources on the PUSCH. As shown in FIG. 3, when an ACK is returned by PUCCH, variable-size ACK resources R1 to R4 exist on PUCCH. As shown in FIG. 4, when ACK is returned by PUSCH, variable-size ACK resources R5 to R8 exist on PUSCH.

Regarding the number of bits of the ACK signal, for example, when performing MIMO (Multiple Input Multiple Output) -2CW (Code Word) communication in the downlink, the wireless communication terminal 200 returns a total of 2 bits as the ACK signal of each CW. . As another example, depending on the configuration of TDD (Time Division Duplex), the radio communication terminal 200 may return an ACK signal for communication of a plurality of downlink subframes in one uplink subframe. In this way, the number of ACK signals to be returned varies depending on MIMO and TDD, but the ACK signal per CW is 1 bit in any case.

The ACK reception MCS-ACK index determination unit 112 determines PUCCH or PUSCH physical resource information. Specifically, the ACK reception MCS-ACK index determination unit 112 reads the DL-MCS of the HARQ process number that receives the ACK / NACK signal from the HARQ process (m) MCS storage unit 113, and then refers to the LUT 111. , Resource allocation information (physical resource allocation and coding information) for receiving an ACK / NACK signal by PUCCH or PUSCH is determined. The HARQ process (m) MCS storage unit 113 stores the DL-MCS for each HARQ process number.

FIG. 5 is a diagram illustrating the configuration of the wireless communication terminal 200 according to the first embodiment. As shown in FIG. 5, the radio communication terminal 200 includes a reception antenna unit 201, a radio reception unit 202, a PDSCH demodulation / decoding unit 203, a CQI measurement unit 204, an AN determination unit 205, a transmission UCI (Uplink Control Information) generation unit 206, The encoding modulation unit 207, the transmission power control unit 208, the wireless transmission unit 209, and the transmission antenna unit 210 are included. Furthermore, the radio communication terminal 200 includes a PDCCH demodulation / decoding unit 211, a DCI determination unit 212, an ACK / NACK transmission MCS-ACK index determination unit 213, and an LUT 214. Each of these components is connected so that signals and data can be input and output in one direction or in both directions.

The receiving antenna unit 201 receives a downlink radio signal. The wireless reception unit 202 performs frequency conversion and A / D conversion. PDSCH demodulation / decoding section 203 demodulates and decodes PDSCH using DL-MCS, HARQ information, and resource information. CQI measurement section 204 measures SINR (Signal-to-Interference and Noise power Ratio) and channel capacity from the received signal, determines CQI based on the measurement result, and reports it according to instructions from base station 100 . The AN determination unit 205 determines whether the PDSCH demodulation / decoding result is ACK or NACK by, for example, CRC (Cyclic Redundancy Check) inspection. The transmission UCI generation unit 206 encodes the ACK / NACK signal. The coding modulation unit 207 includes a control signal coding modulation unit 207a and a main signal coding modulation unit 207b, and performs modulation of PUCCH or PUSCH and arrangement to physical resources for each signal. The transmission power control unit 208 controls the power for transmitting the ACK signal using PUCCH or PUSCH, for example. The wireless transmission unit 209 performs D / A conversion and frequency conversion. The transmission antenna unit 210 transmits an uplink radio signal.

The PDCCH demodulation / decoding unit 211 performs blind detection of the PDCCH using an RNTI (Radio Network Temporary Identifier) as a terminal identifier. When the PDCCH addressed to the terminal is detected by the blind detection, the DCI determination unit 212 decodes the demodulated decoding information including DL-MCS and HARQ information. The ACK / NACK transmission MCS-ACK index determination unit 213 determines PUCCH or PUSCH physical resource information. Specifically, the ACK / NACK transmission MCS-ACK index determination unit 213 refers to the LUT 214 using the received DCI DL-MCS addressed to its own terminal, and allocates the PUCCH or PUSCH resource arrangement for transmitting the ACK / NACK signal. Information (physical resource allocation and coding information) is determined. Since the LUT 214 has the same configuration as the LUT 111 described above, detailed description thereof is omitted.

Next, the operation of a wireless communication system including the base station 100 and the wireless communication terminal 200 will be described.

FIG. 6 is a diagram for explaining the operation (HARQ sequence) of the wireless communication system. In S <b> 1, the wireless transmission unit 209 of the wireless communication terminal 200 reports the CQI to the base station 100 via the transmission antenna unit 210 by PUCCH or PUSCH.

The PDSCH / MCS control unit 110 of the base station 100 determines the downlink MCS using the CQI and LUT 111 reported in the uplink (S2). Next, the PDSCH / MCS control unit 110 generates a new HARQ process (m) (S3), and notifies that there is downlink transmission of the HARQ process (m) to the radio communication terminal 200 by PDCCH (DCI). Notify (S4). At the same time, the base station 100 also transmits PDSCH (traffic data) to the radio communication terminal 200 (S5).

The DCI of the PDCCH includes MCS as information for demodulating and decoding PDSCH traffic data (downlink main signal), and information indicating the number of HARQ transmissions. The wireless communication terminal 200 analyzes the DCI received in S4, refers to each information of the MCS and HARQ transmission frequency, and demodulates and decodes the traffic data received in S5. At this time, if the number of HARQ transmissions is 0 (initial transmission), the demodulated data is decoded as it is. If it is other than 0 (retransmission), the previous received signal and the current received signal are combined by software. Decrypt from.

In S6, the AN determination unit 205 of the wireless communication terminal 200 determines ACK / NACK from the decoding result of PDSCH using CRC (Cyclic Redundancy Check). Next, the ACK / NACK transmission MCS-ACK index determination unit 213 determines an ACK / NACK reply resource by referring to the LUT 214 (S7). Thereafter, the wireless communication terminal 200 executes an encoding process such as bit repetition, and returns a 1-bit ACK / NACK signal per CW to the base station 100 via the PUCCH or the PUSCH (UCI transmission) (S8).

For example, when the ACK index of the LUT 214 is “1”, the radio communication terminal 200 performs UCI transmission using only the PUCCH # 1-1 as usual, but when the ACK index is “2”, the PUCCH # 1 -1 and PUCCH # 1-2 are used to perform encoding by repeating the ACK bit twice. Similarly, when the ACK index is “3”, the radio communication terminal 200 uses PUCCH # 1-1, PUCCH # 1-2, and PUCCH # 1-3, and performs encoding by repeating the ACK bit three times. Do.

On the other hand, the base station 100 stores the MCS of the HARQ process (m) newly generated in S3 (S9), and determines the resource in which the ACK / NACK signal is allocated according to the MCS of the corresponding downlink signal. Determine (S10). When the PUCCH / PUSCH demodulation / decoding unit 103 of the base station 100 detects a reply from S8, the PUCCH / PUSCH demodulation / decoding unit 103 synthesizes a soft decision value based on the number of repetitions corresponding to the ACK index, and demodulates and decodes the PUCCH or PUSCH (S11).

Thereafter, the base station 100 selects new transmission or retransmission according to the UCI determination of the HARQ process (m). That is, the base station 100 analyzes the UCI of the uplink channel and determines whether the analysis result is ACK / NACK / DTX (S12). In the case of ACK, the base station 100 generates a new HARQ process (m) as in S3 (S13), and in the case of NACK / DTX, the communication of the HARQ process (m) generated in S3. Is re-successful and the HARQ process (m) is retransmitted (S14). Thereafter, the PDSCH / MCS control unit 110 of the base station 100 notifies the radio communication terminal 200 by PDCCH (DCI) that there is downlink transmission of the HARQ process (m), similarly to S4 (S15). . Then, the base station 100 also transmits PDSCH (traffic data) to the wireless communication terminal 200 as in S5 (S16).

The wireless communication terminal 200 uses UL-MCS (Up Link-Modulation and Coding Scheme) determined by uplink signal scheduling instead of DL-MCS of the downlink main signal when ACK is returned using PUSCH. ACKindex may be determined from LUT 214.

In addition, the base station 100 may notify the LUT 111 that the ACK index definition described above is included in the cell as system information, or may be individually set for each wireless communication terminal 200. FIG. 7 is a diagram illustrating an example of signaling when the LUT 111 including the ACK index definition is individually set for each wireless communication terminal 200.

In S21, the base station 100 transmits the LUT 111 to the wireless communication terminal 200 as RRC Connection Reconfiguration. In S22, the wireless communication terminal 200 selects the LUT 111 transmitted in S21 as a reference table (MCS table) when determining the used resources in S7. Then, the wireless communication terminal 200 returns RRC Connection Reconfiguration Complete to the base station 100 (S23).

Next, the resource allocation process in the first embodiment will be described in more detail. FIG. 8 is a diagram for explaining resource allocation by the control signal modulation unit 107a of the base station 100 according to the first embodiment. As shown in FIG. 8, when the ACK / NACK resource number is k (k = 1, 2,..., ACK _index ), the resource arrangement m _k is the maximum allowable resource number K _max , Using the resource number m calculated by the method (3Gpp TS36.211 v15.0.0), it can be calculated by the following equation (1).

m _k = (m + k−1) mod K _max (1)

K _max is equal to twice the maximum value of the ACK _index defined in the MCS table, as shown in the following equation (2).

_{_{K max = 2 × ACK index _MAX}} ··· (2)

In the ACK resource map illustrated in FIGS. 3 and 4, ACK _indexMAX = 4.

The base station 100 executes RE (Resource Element) placement processing (mapping) according to the procedure shown in FIG. 8 with Z (i) as the encoded PUCCH symbol. As shown in FIG. 8, when ACKindex = 1 (T1; Yes), since there is no increase in resources (T2), the base station 100 is arranged according to the following equation (3) also shown in FIG. Processing is executed (T3).

On the other hand, when ACKindex> 1 (T1; No), the base station 100 performs resource calculation for increasing resources (T4), and then follows the following equation (4) shown in FIG. A new arrangement process is executed (T5).

Note that the RE arrangement processing by the PUCCH / PUSCH demodulation / decoding unit 103 is the same as the RE arrangement processing by the control signal modulation unit 107a.

FIG. 9 is a diagram for explaining resource allocation by the main signal modulation unit 107b of the base station 100 according to the first embodiment. In UL-SCH (Up Link-Shared CHannel) coding, the base station 100 sets the number of ACK / NACK signals to be transmitted as O _ACK and the number of ACK / NACK modulation symbols to be transmitted as Q ′ as shown in FIG. The RE placement process is executed according to the procedure shown in FIG. As shown in FIG. 9, when ACKindex = 1 (T11; Yes), there is no increase in resources (T12), so that the base station 100 performs UL-SCH according to the following equation (5) also shown in FIG. The number of modulation symbols is determined by the encoding process (T13). Then, the base station 100 modulates the main signal with the determined number of symbols (T14), and executes RE arrangement processing (T15).

On the other hand, when ACKindex> 1 (T11; No), the base station 100 executes resource calculation for increasing resources (T16), and then performs UL− according to the following equation (6) shown in FIG. The number of modulation symbols is determined by the SCH encoding process (T17). Then, the base station 100 modulates the main signal with the determined number of symbols (T18), and executes RE arrangement processing (T19).

FIG. 10 is a diagram for explaining variables used in Expression (5) and Expression (6). In FIG. 10, “1” indicates presence and “0” indicates absence regarding the presence or absence of the subframe head symbol of the first PUCSH transmission. Similarly, regarding the presence / absence of the subframe final symbol of the first PUCSH transmission, “1” indicates presence and “0” indicates absence.

As described above, the radio communication system according to the first embodiment performs radio communication between the base station 100 and the radio communication terminal 200 by applying HARQ and AMC. Base station 100 includes PDSCH / MCS control section 110, ACK reception MCS-ACK index determination section 112, and radio reception section 102. The PDSCH / MCS control unit 110 determines the encoding and modulation scheme (MCS) of the downlink main signal to be transmitted to the radio communication terminal 200. The ACK reception MCS-ACK index determination unit 112 receives resources (for example, PUCCH size) for receiving a response signal (ACK) to the main signal according to the coding and modulation schemes determined by the PDSCH / MCS control unit 110. , Arrangement, number) are variably determined. The radio reception unit 102 receives the response signal using the resource determined by the ACK reception MCS-ACK index determination unit 112. The wireless communication terminal 200 includes a wireless reception unit 202, an ACK / NACK transmission MCS-ACK index determination unit 213, and a wireless transmission unit 209. The radio reception unit 202 receives the encoding and modulation scheme determined by the PDSCH / MCS control unit 110. The ACK / NACK transmission MCS-ACK index determination unit 213, depending on the coding and modulation scheme received by the radio reception unit 202, resources for transmitting the response signal (ACK) (for example, the size, arrangement, and PUCCH of the PUCCH) Number) is variably determined. Radio transmitting section 209 transmits the response signal using the resource determined by ACK / NACK transmission MCS-ACK index determining section 213.

More specifically, the base station 100 determines an encoding and modulation scheme (MCS) of a signal to be transmitted to the radio communication terminal 200, an encoding and modulation scheme applied to the signal, and a response signal for the signal The resource is determined by referring to the association information (LUT 111) with the resource used for transmitting (ACK), and the response signal transmitted from the radio communication terminal 200 is received using the resource. Also, the radio communication terminal 200 receives information on the determined coding and modulation scheme, refers to the association information of resources used for transmission of a response signal for the received coding and modulation scheme, and determines the resource The response signal is transmitted to the base station 100 using the resource.

As described above, in the wireless communication system according to the present embodiment, the resource number and the bit repetition coding number of the ACK / NACK signal returned by the UL channel are associated with the MCS of the corresponding PDSCH. Thereby, the base station 100 dynamically controls PUCCH or PUSCH resource allocation by MCS of PDSCH. In other words, the base station 100 adaptively determines the resource size for ACK / NACK reply from the MCS situation of the downlink main signal when performing ACK reply at low SNR, and repeats the number of ACK bit repetition codings ( ACKindex). As a result, ACK reception quality can be improved while maintaining high resource utilization efficiency against a fixed increase in resources. As a result, non-delivery of the ACK signal is suppressed.

In the base station 100, the radio reception unit 102 receives radio quality information (CQI) reported from the radio communication terminal 200. The PDSCH / MCS control unit 110 can also determine the coding and modulation scheme according to the radio quality information (CQI). Thereby, the base station 100 can determine the resource for receiving the ACK signal accurately and accurately according to the communication environment of the radio communication terminal 200.

In the base station 100, the ACK reception MCS-ACK index determination unit 112 controls the resource by controlling the number of transmission resources of the response signal and the number of repetition coding (ACK index) of the bits (ACK bits) of the response signal. It is good also as what determines. Thereby, the base station 100 can determine appropriately the resource for making an ACK signal reach | attain reliably from the radio | wireless communication terminal 200 to the base station 100 without excess and deficiency.

Further, in the radio communication method according to the present embodiment, the encoding and modulation schemes applied to the signal transmitted from the base station 100, which is a radio apparatus, to the radio communication terminal 200, which is another radio apparatus, and the response signal to the signal Associated with the resource used to transmit

Next, Example 2 will be described. The configuration of the wireless communication system in the second embodiment is the same as the configuration of the wireless communication system in the first embodiment described above. The configurations of the base station and the wireless communication terminal in the second embodiment are the same as the configurations of the base station 100 and the wireless communication terminal 200 in the first embodiment shown in FIG. Therefore, in the second embodiment, the same reference numerals are used for the same components as in the first embodiment, and detailed description thereof is omitted. The difference between the second embodiment and the first embodiment is a wireless communication system. Specifically, the first embodiment has been described assuming LTE as an object to which the technology according to the present embodiment is applied, but in the second embodiment, NR (New Radio) is assumed.

In the second embodiment, the base station 100 and the wireless communication terminal 200 have predetermined common LUTs 111a and 111b, respectively. The ACK reception MCS-ACK index determination unit 112 refers to these LUTs 111a and 111b and identifies an ACK index suitable for the MCS of the downlink main signal. FIG. 11 is a diagram illustrating a data storage example of the LUT 111a according to the second embodiment when 256QAM (Quadrature Amplitude Modulation) is not applied. As shown in FIG. 11, taking the main signal MCS table in the NR system as an example, ACKindex is defined in addition to MCSindex, Modulation Order, Target code Rate, and Spectral efficiency. As a result, even when NR is applied, it is possible to determine the ACK index according to the downlink main signal MCS.

FIG. 12 is a diagram illustrating a data storage example of the LUT 111b according to the second embodiment when 256QAM is applied. As shown in FIG. 12, the table structure when 256QAM is applied is the same as that when 256QAM is not applied, but the numerical values such as Target code Rate and Spectral efficiency stored in each field are high.

Next, the operation of the second embodiment will be described. Since the operation of the second embodiment is the same as the operation of the wireless communication system according to the first embodiment described with reference to FIGS. 6 and 7, detailed description thereof will be omitted, and resource allocation processing in the second embodiment will be described below. Will be described in more detail. FIG. 13 is a diagram for explaining resource allocation by the control signal modulation unit 107a of the base station 100 according to the second embodiment. The process shown in FIG. 13 has the same basic flow as the process shown in FIG. 8 and will not be described in detail. However, in URLLC with a low SNR, use of a small block UCI is assumed, and PUCCH format0 is Used.

As shown in FIG. 13, the resource arrangement of PUCCH format 0 is specified by higher layer signaling using the following parameters.
PUCCH-resource-config-PF0 (3Gpp TS38.213 v15.0.0)
PUCCH-starting-PRB (Physical Resource Brock): PRB position (when starting)
PUCCH-2nd-hop-PRB: PRB position (during hopping)
PUCCH-F0-F2-starting symbol: Symbol start position PUCCH-F0-F2-number-of-symbols: Number of symbols

Here, if the ACK _index is applied to the number of symbols, the number of symbols N _symb can be calculated by the following equation (7).

The base station 100 executes RE arrangement processing (mapping) according to the procedure shown in FIG. 13 with the encoded PUCCH symbol as Z (i). As shown in FIG. 13, when ACKindex = 1 (T21; Yes), since there is no increase in resources (T22), the base station 100 executes a conventional arrangement process (T23). On the other hand, when ACKindex> 1 (T21; No), the base station 100 performs resource calculation for increasing resources using the above equation (7) (T24), and then sets each parameter described above. The new arrangement process used is executed (T25).

FIG. 14 is a diagram for explaining resource allocation by the main signal modulation unit 107b of the base station 100 according to the second embodiment. In UL-SCH encoding, the base station 100 sets the number of bits of the ACK / NACK signal to be transmitted as O _ACK and the number of modulation symbols of the ACK / NACK to be transmitted as Q ′ by the procedure shown in FIG. Execute placement processing. As shown in FIG. 14, when ACKindex = 1 (T31; Yes), there is no increase in resources (T32). Therefore, the base station 100 performs UL-SCH according to the following equation (8) also shown in FIG. The number of modulation symbols is determined by the encoding process (T33). Then, the base station 100 modulates the main signal with the determined number of symbols (T34), and executes RE arrangement processing (T35).

On the other hand, when ACKindex> 1 (T31; No), the base station 100 executes resource calculation for increasing resources (T36), and then performs UL− according to the following equation (9) shown in FIG. The number of modulation symbols is determined by the SCH encoding process (T37). Then, the base station 100 modulates the main signal with the determined number of symbols (T38), and executes RE arrangement processing (T39).

FIG. 15 is a diagram for explaining variables used in the equations (8) and (9). Of the formulas (8) and (9), the formula (8) is a conventional calculation formula (3Gpp TS38.212 v15.0.0). L represents the number of CRC bits as shown in FIG. 15, but in the low LCNR LCLC, it is assumed that the small block UCI is used, and therefore L = 0 in the above equations (8) and (9).

As described above, the base station 100 according to the second embodiment performs wireless communication (for example, transmission of a main signal and reception of an ACK signal) with the wireless communication terminal 200 by NR. Therefore, the resource (for example, PUCCH) variable control technology for transmitting and receiving the ACK signal can be applied not only to an existing wireless communication method such as LTE but also to a 5G (Generation) wireless communication method.

In each of the above-described embodiments, CQI and SNR are used as indicators for determining radio quality. However, the information is not limited to these information. For example, RSSI (Received Signal Strength Indication), RSRP (Reference Signal Received Power), RSRQ (Reference Signal) It may be information on the link status such as Received Quality (RSCP), Received Signal Code Power (RSCP), or FER (Frame Error Rate). In each of the above embodiments, the wireless communication terminal 200 is assumed to be a wireless communication terminal such as a mobile phone, a smart phone, or a PDA (Personal Digital Assistant). However, the present invention is not limited to the wireless communication terminal, and the ACK The present invention can be applied to various communication devices that can allocate resources.

Each component of the base station 100 and the wireless communication terminal 200 does not necessarily need to be physically configured as illustrated. In other words, the specific mode of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed in arbitrary units according to various loads or usage conditions. -It can also be integrated and configured. For example, the control signal encoding unit 106a and the main signal encoding unit 106b, or the control signal encoding modulation unit 207a and the main signal encoding modulation unit 207b may be integrated as one component. On the other hand, for example, with respect to the ACK reception MCS-ACK index determination unit 112 of the base station 100, the ACK reception resource determination part 112 and the ACK bit repetitive coding number (ACK index) selection part may be distributed. Good. Further, the HARQ process (m) MCS storage unit 113 may be connected as an external device of the base station 100 via a network or a cable.

DESCRIPTION OF SYMBOLS 100 Base station 101 Reception antenna part 102 Radio | wireless receiving part 103 PUCCH / PUSCH demodulation decoding part 104 AN determination part 105 HARQ control buffer part 106 Encoding part 106a Control signal encoding part 106b Main signal encoding part 107 Modulation part 107a Control signal modulation Unit 107b main signal modulation unit 108 wireless transmission unit 109 transmission antenna unit 110 PDSCH / MCS control unit 111 LUT
111a LUT without 256QAM
111b LUT with 256QAM application
112 ACK reception MCS-ACK index determination unit 113 HARQ process (m) MCS storage unit 200 wireless communication terminal 201 reception antenna unit 202 wireless reception unit 203 PDSCH demodulation / decoding unit 204 CQI measurement unit 205 AN determination unit 206 transmission UCI generation unit 207 encoding Modulation unit 207a Control signal coding modulation unit 207b Main signal coding modulation unit 208 Transmission power control unit 209 Wireless transmission unit 210 Transmission antenna unit 211 PDCCH demodulation decoding unit 212 DCI determination unit 213 ACK / NACK transmission MCS-ACK index determination unit 214 LUT
R1-R4 Variable ACK resource on PUCCH R5-R8 Variable ACK resource on PUSCH

Claims

A first determination unit that determines a coding and modulation scheme of a signal to be transmitted to a wireless communication terminal;
A second deciding unit that decides the resource by referring to association information between a coding and modulation scheme applied to the signal and a resource used for transmission of a response signal to the signal;
And a reception unit that receives the response signal transmitted using the resource.
The receiving unit receives wireless quality information from a wireless communication terminal,
The base station according to claim 1, wherein the first determination unit is capable of determining the encoding and modulation schemes according to the radio quality information.
The base station according to claim 1, wherein the second determination unit determines the resource by controlling the number of transmission resources of the response signal.
The base station according to claim 1, wherein the base station transmits the signal and receives the response signal by NR (New Radio) with the wireless communication terminal.
A receiving unit that receives information on a coding and modulation scheme applied to a signal transmitted by the base station;
A determination unit that determines the resource by referring to association information between a coding and modulation scheme applied to the signal and a resource used to transmit a response signal to the signal;
A wireless communication terminal comprising: a transmission unit that transmits the response signal using the resource.
A wireless communication system for performing wireless communication between a base station and a wireless communication terminal,
The base station
A first determination unit for determining a coding and modulation scheme of a signal to be transmitted to the wireless communication terminal;
A second deciding unit that decides the resource by referring to association information between a coding and modulation scheme applied to the signal and a resource used for transmission of a response signal to the signal;
A first receiving unit that receives the response signal transmitted from the wireless communication terminal using the resource;
The wireless communication terminal is
A second receiver for receiving information on the coding and modulation schemes determined by the first determiner;
A third determination unit that determines the resource with reference to resource association information used for transmission of a response signal to the coding and modulation scheme received by the second reception unit;
A wireless communication system comprising: a transmission unit that transmits the response signal to the base station using the resource.
A wireless communication method characterized in that a coding and modulation scheme applied to a signal transmitted from a wireless device to another wireless device is associated with a resource used for transmitting a response signal to the signal.