WO2020090029A1

WO2020090029A1 - Wireless transmission device, wireless reception device, and wireless communication system

Info

Publication number: WO2020090029A1
Application number: PCT/JP2018/040491
Authority: WO
Inventors: 義博河▲崎▼; 大出　高義
Original assignee: 富士通株式会社
Priority date: 2018-10-31
Filing date: 2018-10-31
Publication date: 2020-05-07

Abstract

This wireless transmission device is provided with a transmission unit and a control unit. The transmission unit transmits a data signal by using a first wireless resource and a second wireless resource. The control unit generates a first reference signal and a second reference signal so that the second reference signal transmitted, together with the data signal, by using the second wireless resource has a prescribed shift amount with respect to a parameter associated with the first reference signal transmitted, together with the data signal, by using the first wireless resource.

Description

Wireless transmitter, wireless receiver, and wireless communication system

The present invention relates to a wireless transmission device and a wireless reception device used in a wireless communication system.

In addition to the large capacity and / or low delay of wireless communication, the communication standard of 5th generation mobile communication (so-called 5G: 5th Generation mobile communication system) is 3GPP in order to support services with various requirements. It is being considered by standardization organizations such as. In 3GPP, 5G is also called NR (New Radio). In 5G, as one of the use cases, support for ultra-reliable and low-latency communication (URLLC: Ultra-Reliable and Low Latency Communications) is assumed. URLLC is expected to be applied to, for example, automatic driving, remote medicine, and industrial equipment IoT.

As one of methods for transmitting URLLC data from a wireless terminal device (hereinafter, abbreviated as a terminal device) to a wireless base station device (hereinafter, abbreviated as a base station) in an uplink wireless link of a 5G wireless system being studied by 3GPP, In addition to the conventional grant-based data transmission method, a grant-free data transmission method is being studied.

In grant-type data transmission, the base station gives a transmission permission (grant) to the terminal device each time the terminal device transmits data. That is, a wireless resource is allocated for each data transmission. On the other hand, in grant-free type data transmission, as shown in FIG. 1, a wireless resource group is assigned in advance to a terminal device that transmits URLLC data. That is, the processing related to the transmission permission is collectively performed in advance. In addition, radio resources are allocated to the terminal device periodically (or quasi-periodically). In the 3GPP specifications, for example, an expression such as “configure grant in semi-static” is described.

-The wireless resource group is set in the cycle P. Further, each radio resource group is composed of K × B OFDM symbols (P, K, and B are used for description in this specification, and different expressions are used in the 3GPP specifications. May be done). That is, each radio resource group is composed of K resource blocks, and each resource block is composed of B OFDM symbols. The value of B is an integer of 1 or more. The B OFDM symbols are continuous in the time domain, but some of the B OFDM symbols may be discontinuous. In the example shown in FIG. 1, each radio resource group is composed of four resource blocks. It should be noted that the resource block used in this specification is used to mean a lump of resources, and is different from the definition of the resource block used in the 3GPP specifications.

The terminal device transmits URLLC data to the base station using one or more resource blocks. Therefore, the terminal device can repeatedly transmit the URLLC data up to K times. Then, high reliability is realized by this repeated transmission. Note that grant-free data transmission is described in Patent Document 1, for example.

WO2017 / 191834

As described above, the terminal device can repeatedly transmit URLLC data up to K times. In the example shown in FIG. 1, URLLC data is repeatedly transmitted up to four times.

However, the terminal device starts transmission of the URLLC data from the allocated resource immediately after the timing when the URLLC data is generated. Then, the terminal device repeatedly transmits the URLLC data up to the last resource block in the wireless resource group.

For example, in the example shown in FIG. 2A, the terminal device transmits the URLLC data by using the wireless resource group # 1. Specifically, the terminal device starts transmission of URLLC data from the resource block 1 of the wireless resource group # 1. Then, the terminal device repeatedly transmits the URLLC data up to the resource block 4 of the wireless resource group # 1. That is, in this case, the URLLC data is repeatedly transmitted four times. It should be noted that the circle marks represent resource blocks to which URLLC data is transmitted.

On the other hand, in the example shown in FIG. 2B, the URLLC data is repeatedly transmitted during the period from the resource block 3 to the resource block 4 in the wireless resource group # 2. That is, in this case, the URLLC data is repeatedly transmitted twice. Further, in the example illustrated in FIG. 2C, the URLLC data is transmitted using only the resource block 4 of the wireless resource group # 3. That is, in this case, the URLLC data is transmitted only once.

Thus, in the conventional transmission method, the number of times the URLLC data is repeatedly transmitted depends on the timing at which the URLLC data is generated and the positional relationship in the time domain of the pre-allocated radio resource. Therefore, the data transmission characteristic (for example, the decoding success rate of the received data in the receiving device) varies depending on the timing at which the URLLC data is generated. As a result, there may occur a case where the quality required by the URLLC service cannot be satisfied.

An object of one aspect of the present invention is to improve data transmission characteristics in wireless communication.

A wireless transmission device according to one aspect of the present invention includes a transmitter that transmits a data signal using a first wireless resource and a second wireless resource, and a transmitter that transmits the data signal using the second wireless resource together with the data signal. The first reference signal such that the second reference signal has a predetermined shift amount with respect to a parameter related to the first reference signal transmitted together with the data signal using the first radio resource. And a control unit that generates the second reference signal.

According to the above aspect, the data transmission characteristic in wireless communication is improved.

It is a figure which shows an example of grant-free type data transmission. It is a figure explaining the subject of the conventional grant-free type data transmission. It is a figure which shows an example of the radio | wireless communications system with which data transmission concerning embodiment of this invention is performed. It is a figure explaining a grant-based system and a grant-free system. It is a figure which shows an example of the data transmission which uses HARQ. It is a figure which shows an example of the method of improving the data transmission characteristic in grant-free type data transmission. It is a figure which shows an example of the data transmission concerning embodiment of this invention. It is a figure explaining the cyclic shift of a pilot signal. It is a figure which shows an example of the method of transmitting a pilot signal. It is a figure which shows an example of the method of generating a pilot signal. It is a figure which shows an example of the method of generating a pilot signal sequence. It is a figure which shows an example of a terminal device. It is a figure which shows an example of a base station. It is a figure which shows an example of a process of a pilot signal processing part. It is a flow chart which shows an example of processing of a terminal unit. It is a flowchart (the 1) which shows an example of a process of a base station. It is a flowchart (the 2) which shows an example of a process of a base station.

FIG. 3 shows an example of a wireless communication system in which data transmission according to the embodiment of the present invention is performed. The wireless communication system is, for example, a fifth generation mobile communication (5G) system. The wireless communication system includes a base station 1 and a terminal device 2. The base station 1 can accommodate a plurality of terminal devices. In the 5G system being studied by 3GPP, the base station may be called gNB and the terminal device may be called UE.

The embodiment of the present invention relates to uplink data transmission for transmitting a signal from the terminal device 2 to the base station 1. Therefore, in the following description, the terminal device 2 and the base station 1 may be referred to as “transmitting device (or wireless transmitting device)” and “receiving device (or wireless receiving device)”, respectively.

FIG. 4 is a diagram for explaining the grant-based method and the grant-free method. In this example, data is transmitted from the terminal device 2 to the base station 1.

In the grant-based method, the terminal device 2 transmits a scheduling request to the base station 1 after data is generated, as shown in FIG. 4 (a). Upon receiving the scheduling request, the base station 1 transmits a grant signal to the terminal device 2. The grant signal includes information designating a transmission permission and a radio resource for uplink. Then, when the terminal device 2 receives the grant signal, the terminal device 2 transmits the data using the designated wireless resource.

In the grant-free method, as shown in FIG. 4B, allocation information representing allocation of uplink radio resources is transmitted from the base station 1 to the terminal device 2 in advance. Then, when the data is generated, the terminal device 2 transmits the data to the base station 1 according to the allocation information. As described above, in the grant-free method, the terminal device 2 transmits data according to the allocation information acquired in advance. Therefore, the delay of the grant-free method is smaller than that of the grant-based method. In one form of the grant-free method, the receiving device (that is, the base station 1) determines that the transmitting device (that is, the terminal device 2) has transmitted the data when the data is successfully decoded. ..

FIG. 5 shows an example of data transmission using HARQ. In a hybrid automatic repeat request (HARQ), an identifier is associated with each HARQ process. In the example shown in FIG. 5, ID1, ID2, ID3 ,. ．． Is associated with. Then, data transmission is performed for each HARQ process. That is, the transmitting device transmits data for each HARQ process, and the receiving device receives data for each HARQ process. The HARQ process is an example of a communication process for transmitting a data signal using a radio resource group.

When data transmission fails, it is retransmitted. In one form of the grant-free method, the transmission device may determine that the data transmission has failed, for example, when the ACK cannot be received even after a predetermined time has elapsed from the data transmission. Then, when the data transmission has failed, the transmission device retransmits the data. At this time, HARQ may perform incremental redundancy (IR: Incremental redundancy) type retransmission control. However, the transmitting device executes data transmission and data retransmission in association with the same identifier. In the example shown in FIG. 5, when the data transmission associated with the HARQ process ID1 fails, the corresponding data retransmission is performed using the radio resource allocated to the HARQ process ID1 after the data transmission. Is being done.

FIG. 6 shows an example of a method for improving data transmission characteristics in grant-free type data transmission. Similar to the example shown in FIG. 1, also in the example shown in FIG. 6, a wireless resource group is assigned in advance to the terminal device 2 transmitting URLLC data. The radio resource group is set in the cycle P. In FIG. 6, each time slot T1, T2 ,. ．． A radio resource group is set in the inside.

Each radio resource group consists of K × B OFDM symbols. That is, each radio resource group is composed of K resource blocks, and each resource block is composed of B OFDM symbols. In the example shown in FIG. 6, K = 4, and each radio resource group is composed of four resource blocks.

In the example shown in FIG. 6, the terminal device 2 repeatedly transmits the URLLC data K times regardless of the timing at which the URLLC data is generated.

Specifically, the terminal device 2 starts data transmission in the third resource block in the resource group of the time slot T1. Here, the circle marks represent resource blocks to which URLLC data is transmitted. Subsequently, the transmission device 2 also transmits data in the fourth resource block. Furthermore, the terminal device 2 also performs data transmission in the first and second resource blocks in the resource group of the time slot T2. As a result, the URLLC data is repeatedly transmitted from the terminal device 2 to the base station 1 four times.

As described above, in the method shown in FIG. 6, the data transmission is repeated across the boundaries of the time slots, so that the number of data transmissions is constant regardless of the timing at which the URLLC data is generated. Therefore, variations in data transmission characteristics (for example, decoding success rate in the receiving device) are suppressed, and communication quality for the URLLC service is improved.

However, the data transmission in the time slot T1 is executed in association with the HARQ process ID1, and the data transmission in the time slot T2 is executed in association with the HARQ process ID2. Further, in the grant-free method, the receiving device (that is, the base station 1) determines that the data is transmitted from the transmitting device (that is, the terminal device 2) when the data is successfully decoded. Therefore, when the base station 1 succeeds in decoding the received data, the base station 1 may not be able to correctly recognize the HARQ process ID associated with the data.

For example, in the embodiment shown in FIG. 6, it is assumed that the first and second data transmissions fail and the third data transmission succeeds. In this case, the base station 1 recognizes the third data transmission without recognizing that the first and second data transmissions have been performed. Therefore, the base station 1 recognizes that the received data is associated with the HARQ process ID2, and processes the data in association with the HARQ process ID2. Then, the base station 1 transmits the ACK associated with the HARQ process ID2 to the terminal device 2. In this case, the terminal device 2 may not be able to determine whether or not the data associated with the HARQ process ID1 has been correctly processed by the base station 1. Then, when the terminal device 2 cannot receive the ACK associated with the HARQ process ID1, the terminal device 2 may perform data retransmission by HARQ.

Further, in the embodiment shown in FIG. 6, it is assumed that the first and third data transmissions are successful. In this case, the base station 1 transmits ACK for the data associated with HARQ process ID1 and ACK for the data associated with HARQ process ID2. That is, the base station 1 transmits two ACKs to the terminal device 2. Therefore, downlink radio resources are excessively consumed.

As described above, in the method shown in FIG. 6, since the data transmission is repeated beyond the boundaries of the time slots, the above-mentioned problem may occur. The wireless communication system according to the embodiment of the present invention has a function or procedure for solving the above-mentioned problems.

FIG. 7 shows an example of data transmission according to the embodiment of the present invention. In this embodiment, as in the case shown in FIG. 6, data is transmitted by the grant-free method. Each radio resource group is composed of 4 resource blocks. Each resource block is composed of B OFDM symbols (B ≧ 1). Then, when the URLLC data is generated, the terminal device 2 repeatedly transmits the URLLC data to the base station 1 four times regardless of the timing when the URLLC data is generated. At this time, the terminal device 2 repeats the data transmission across the boundary of the time slots as necessary. That is, the terminal device 2 repeats data transmission over a plurality of time slots as necessary. In the example shown in FIG. 7, the first and second data transmissions are performed using the radio resource group of time slot T1, and the third and fourth data transmissions are performed using the radio resource group of time slot T2. Executed. HARQ process ID1 is associated with the radio resource group of time slot T1, and HARQ process ID2 is associated with the radio resource group of time slot T2.

In the above data transmission, each resource block includes a pilot signal in addition to the data signal. Further, each resource block may include a control signal that includes information about the data signal and other information. Here, the value of the pilot signal (amplitude, phase, parameter value regarding the code string forming the pilot signal, etc.) and the transmission power are known. Therefore, the receiving device (that is, the base station 1) can estimate the radio link state (propagation loss and phase rotation) between the terminal device 2 and the base station 1 by using the pilot signal (such estimation is Also called channel estimation). That is, the base station 1 can demodulate the received data signal using the pilot signal. The pilot signal is also called a reference signal (RS) in the 3GPP wireless system.

In the embodiment shown in FIG. 7, the pilot signal P is transmitted in each resource block of the time slot T1 and the pilot signal P2 is transmitted in each resource block of the time slot T2. Here, the pilot signal transmitted in one time slot and the pilot signal transmitted in the other time slot are associated with each other when the repetition of data transmission is performed across time slot boundaries. That is, the pilot signal P and the pilot signal P2 are associated with each other.

As an example, the sequence of the pilot signal P2 (that is, the code string) is generated by cyclically shifting the sequence of the pilot signal P. In this case, the sequence of pilot signals P2 is generated from the sequence of pilot signals P using equation (1).

α represents the cyclic shift amount. s represents a value from zero to L-1. L represents the sequence length of the pilot signal. Thus, s identifies the sth symbol in the sequence of pilot signals.

FIG. 8 is a diagram for explaining cyclic shift of the pilot signal. In this embodiment, the pilot signal has a sequence length of L. That is, the pilot signal P is represented by L symbols P (0) P (1) P (2) ... P (L-3) P (L-2) P (L-1). Here, each symbol P (i) is represented by a complex number, for example. In this case, each symbol P (i) represents a phase corresponding to the ratio of the real number component and the imaginary number component of the complex number.

The pilot signal P2 sequence is generated by cyclically shifting the pilot signal P sequence by α. Here, the cyclic shift amount α is 2. Therefore, the pilot signal P2 is represented by P (L-2) P (L-1) P (0) P (1) P (2) ... P (L-3).

FIG. 9 shows an example of a method of transmitting a pilot signal. In this example, the resource block has 8 symbols (sy1 to sy8) in the time domain and 6 subcarriers (sc1 to sc6) in the frequency domain. Further, the pilot signal is assumed to be transmitted using 6 resource elements (RE1 to RE6) as shown in FIG. 9 (a). It should be noted that, in reality, the resource block may be composed of more symbols and more subcarriers. Also, the pilot signal is transmitted using more resource elements.

The sequence length L of the pilot signal is 6 in this embodiment. The pilot signal P is represented by P (0) to P (5). The symbols P (0) to P (5) of the pilot signal P are arranged in the resource elements RE1 to RE6, respectively, as shown in FIG. 9 (b). That is, P (0) to P (5) are transmitted using the resource elements RE1 to RE6, respectively. In this case, for example, the resource element RE1 (that is, the second symbol of the subcarrier sc2) is used to transmit a signal in the phase corresponding to P (0). The other resource elements RE2-RE6 are also used for transmitting signals in the corresponding phases.

The pilot signal P2 is generated by cyclically shifting the pilot signal P by α. In this embodiment, the cyclic shift amount α is 2. In this case, the pilot signal P2 is represented by P (4) P (5) P (0) P (1) P (2) P (3). Therefore, as shown in FIG. 9C, the resource elements RE1, RE2, RE3, RE4, RE5, and RE6 have P (4), P (5), P (0), P (1), and P (4), respectively. (2) and P (3) are arranged. In this case, for example, the resource element RE1 (that is, the second symbol of the subcarrier sc2) is used to transmit a signal in the phase corresponding to P (4). The other resource elements RE2-RE6 are also used for transmitting signals in the corresponding phases.

The cyclic shift amount α is determined using, for example, the HARQ process ID. Here, as shown in FIG. 10, it is assumed that the URLLC data is repeatedly transmitted four times across the boundaries of time slots. That is, URLLC data is repeatedly transmitted four times using the resource group of time slot T1 and the resource group of time slot T2. Then, it is assumed that the HARQ process ID associated with the resource group of the time slot T1 is “n1” and the HARQ process ID associated with the resource group of the time slot T2 is “n2”. When the number of HARQ processes in the wireless communication system is N, each HARQ process ID is preferably smaller than N.

In this case, the cyclic shift amount α is generated, for example, based on the difference between the two HARQ process IDs. That is, α = n2-n1 or α = n1-n2. Alternatively, the cyclic shift amount α is generated based on the HARQ process ID associated with the resource group including the resource block in which the URLLC data is transmitted for the first time. That is, α = n1. In this way, at least one of n1 and n2 is associated with the shift amount.

Alternatively, the cyclic shift amount α may be determined based on “how many times it is repeated”. For example, the cyclic shift amount α_r applied to the pilot signal transmitted in the r-th data transmission is represented by Expression (2).

L represents the sequence length of the pilot signal. R represents the number of repetitions of data transmission. In the example shown in FIG. 10, R = 4. “Floor” represents a function that obtains an integer by truncating the decimal places.

In this case, if L = 30, the cyclic shift amount α_3 applied to the pilot signal transmitted in the third data transmission is 14. Further, the cyclic shift amount α_4 applied to the pilot signal transmitted in the fourth data transmission is 21.

The pilot signal P is generated, for example, by the method shown in FIG. In this example, the pilot signal P is generated from the sequence A. Here, when the sequence length of the pilot signal P is L, the length of the sequence A is represented by L2. L2 is, for example, the largest value among prime numbers smaller than L.

Sequence A is generated by equation (3).

m represents a value from zero to L2-1. L2 represents the length of the sequence A. Therefore, m identifies the mth symbol in sequence A. u is a parameter indicating the sequence group number. v is a parameter indicating the sequence base number. The sequence A is described in Section 5.2.2.1 of 3GPP specification TS38.211, for example. A (m) and L2 correspond to Xq (m) and Nzc of TS38.211, respectively.

In this case, the pilot signal P is generated by adding the beginning portion Aa of the sequence A to the sequence A. The length of the head portion Aa is LL2.

Further, the pilot signal P2 is generated by shifting the parameters (u, v in the equation (3)) in the sequence forming the pilot signal P (sequence A in FIG. 11) by a predetermined amount. May be. For example, at least one of n1 and n2 is associated with the shift amount. n1 represents the HARQ process ID associated with the resource group of the time slot T1, and n2 represents the HARQ process ID associated with the resource group of the time slot T2.

FIG. 12 shows an example of the terminal device 2. As shown in FIG. 12, the terminal device 2 includes a radio reception unit 21, a demodulation / decoding unit 22, a radio resource management unit 23, a transmission unit 24, a control unit 25, and a pilot signal generation unit 26. However, the terminal device 2 may include other circuits or functions not shown in FIG.

The radio receiver 21 receives the downlink signal transmitted from the base station 1 via the receiving antenna. The demodulation / decoding unit 22 demodulates the downlink signal received by the wireless reception unit 21. Further, the demodulation / decoding unit 22 decodes the demodulated downlink signal. The output signal of the demodulation / decoding unit 22 includes data and control information. The control information includes wireless resource information. The radio resource information includes information indicating radio resources allocated for transmitting the uplink signal. Then, the radio resource management unit 23 acquires radio resource information from the output signal of the demodulation / decoding unit 22. The data and other control information are processed by a data processing circuit and a control information processing circuit (not shown), respectively.

The transmission unit 24 includes a data signal generation unit 27, a buffer 28, an encoding / modulation unit 29, a multiplexing unit 30, and a wireless transmission unit 31, and generates an uplink signal from the data generated by the terminal device 2. The uplink signal is transmitted to the base station 1 via the transmission antenna.

The control unit 25 controls the operation of the transmission unit 24 according to the wireless resource information. That is, the control unit 25 controls the generation of the data signal based on the radio resource information. Further, the control unit 25 controls repetition of data transmission. Further, the control unit 25 provides the pilot signal generation unit 26 with information for generating a pilot signal.

The data signal generation unit 27 generates a data signal from the data generated by the terminal device 2. The data signal generated by the data signal generation unit 27 is stored in the buffer 28 and guided to the encoding / modulation unit 29. The data signal stored in the buffer 28 is read according to the instruction given from the control unit 25. The data signal read from the buffer 28 is used in the second to L-th data transmission.

The encoding / modulation unit 29 encodes the data signal. The encoding / modulation unit 29 also modulates the encoded data signal.

The pilot signal generation unit 26 generates a pilot signal according to an instruction given by the control unit 25. Specifically, the pilot signal generation unit 26 generates the pilot signal P or the pilot signal P2 according to the instruction given from the control unit 25. The pilot signal P is generated, for example, by the method shown in FIG. Pilot signal P2 is generated based on pilot signal P. For example, pilot signal P2 is generated by cyclically shifting the sequence of pilot signal P by α as shown in FIGS. In this case, the cyclic shift amount α is calculated by the control unit 25 and given to the pilot signal generation unit 26. The pilot signal generator 26 may be a part of the controller 25.

The multiplexer 30 multiplexes the data signal output from the encoder / modulator 29 and the pilot signal generated by the pilot signal generator 26 according to an instruction given from the controller 25. The wireless transmission unit 31 transmits the output signal of the multiplexing unit 30 to the base station 1 via the transmission antenna. At this time, the wireless transmission unit 31 may up-convert the frequency of the output signal of the multiplexing unit 30 into the designated frequency band.

The control unit 25 and the pilot signal generation unit 26 are realized by, for example, a processor system including a processor and a memory. In this case, the processor provides the functions of the control unit 25 and the pilot signal generation unit 26 by executing the software program stored in the memory. However, a part of the functions of the control unit 25 and the pilot signal generation unit 26 may be realized by a hardware circuit.

FIG. 13 shows an example of the base station 1. As shown in FIG. 13, the base station 1 includes a radio reception unit 41, a pilot signal processing unit 42, a demodulation unit 43, a decoding unit 44, a control unit 45, a radio resource management unit 46, a control signal generation unit 47, an encoding / coding unit. The modulator 48 and the wireless transmitter 49 are provided. However, the base station 1 may include other circuits or functions not shown in FIG.

The wireless reception unit 41 receives the uplink signal transmitted from the terminal device 2 via the reception antenna. The uplink signal received by the wireless reception unit 41 is guided to the demodulation unit 43 via a buffer (not shown). However, the pilot signal included in the uplink signal is guided to the pilot signal processing unit 42.

The pilot signal processing unit 42 holds a replica of the pilot signal P. The pilot signal P is known as described with reference to FIG. Then, the pilot signal processing unit 42 compares the received pilot signal (P or P2) with a replica of the pilot signal P, and thus the link propagation indicating the characteristics of the wireless link between the terminal device 2 and the base station 1. Generate information (sometimes referred to as channel estimation results). When the uplink signal includes the pilot signal P2, the pilot signal processing unit 42 calculates the cyclic shift amount α between the pilot signal P and the pilot signal P2.

The demodulation unit 43 demodulates the uplink signal using the link propagation information generated by the pilot signal processing unit 42. The decoding unit 44 decodes the output signal of the demodulation unit 43. The output signal of the decoding unit 44 includes data and control information. The control information is guided to the control unit 45.

The control unit 45 controls the operation of the base station 1. Further, the control unit 45 can specify the HARQ process ID associated with the received data, based on the cyclic shift amount α calculated by the pilot signal processing unit 42.

The wireless resource management unit 46 manages wireless resources allocated to communication between the base station 1 and the terminal device 2. Then, the wireless resource management unit 46 generates wireless resource information. As described above, the radio resource information includes the information indicating the radio resource for transmitting the uplink signal. The control signal generation unit generates a control signal to be given to the terminal device 2. The control signal includes wireless resource information generated by the wireless resource management unit 46.

The encoding / modulation unit 48 encodes the control signal. Although not shown, the encoding / modulation unit 48 also encodes a data signal. Then, the encoding / modulation unit 29 modulates the encoded signal. The wireless transmission unit 49 transmits the output signal of the encoding / modulation unit 48 to the terminal device 2 via the transmission antenna. At this time, the wireless transmission unit 49 may up-convert the frequency of the output signal of the encoding / modulation unit 48 into a designated frequency band.

The pilot signal processing unit 42, the control unit 45, and the radio resource management unit 46 are realized by, for example, a processor system including a processor and a memory. In this case, the processor provides the functions of the pilot signal processing unit 42, the control unit 45, and the radio resource management unit 46 by executing the software program stored in the memory. However, some of the functions of the pilot signal processing unit 42, the control unit 45, and the radio resource management unit 46 may be realized by a hardware circuit.

FIG. 14 shows an example of processing of the pilot signal processing unit 42. In this embodiment, the pilot signal processing unit 42 holds a replica of the pilot signal P, as shown in FIG. The pilot signal extracted from the received signal is stored in the shift register. Further, the correlator calculates the correlation between the pilot signal stored in the shift register and the replica.

When the correlation between the received pilot signal and the replica is higher than a predetermined threshold value, the pilot signal processing unit 42 determines that the received pilot signal is the pilot signal P. When the correlation between the received pilot signal and the replica is lower than the threshold, the pilot signal processing unit 42 calculates the correlation with the replica while cyclically shifting the sequence of the pilot signal stored in the shift register by one symbol. Then, as shown in FIG. 14B, when the shift amount is “x”, the peak of the correlation value is detected. In this case, the pilot signal processing unit 42 determines that the shift amount between the received pilot signal and the pilot signal P is “x”. Then, the pilot signal processing unit 42 determines that the sequence obtained by shifting the sequence of the pilot signal P by "x" is the pilot signal P2. In this way, the pilot signal processing unit 42 can calculate the cyclic shift amount α between the pilot signal P and the pilot signal P2.

FIG. 15 is a flowchart showing an example of processing of the terminal device 2. The process of this flowchart is executed, for example, when the terminal device 2 is connected to the base station 1. Further, in this embodiment, each radio resource group is assumed to be composed of K resource blocks.

In S1, the terminal device 2 receives wireless resource information from the base station 1. As described above, the radio resource information includes the information indicating the radio resource for transmitting the uplink signal. Further, the wireless resource information may include information indicating a wireless resource group. In this case, the radio resource information includes information indicating the correspondence between the radio resource group and the HARQ process ID, information indicating the number of resource blocks in the radio resource group, and the like. Then, the control unit 25 schedules wireless resources according to the received wireless resource information.

At S2, the data signal generation unit 27 waits for data to be transmitted to the base station 1. In this embodiment, the terminal device 2 transmits URLLC data to the base station 1.

When the URLLC data is generated, the data signal generation unit 27 generates the data signal and the pilot signal generation unit 26 generates the pilot signal P in S3. The generated data signal is stored in the buffer 28. The pilot signal P is generated, for example, by the method shown in FIG.

In S4 to S5, the control unit 25 acquires the radio resource that can be used to transmit the signal (that is, the data signal and the pilot signal P) generated in S3. At this time, the control unit 25 acquires the resource block that becomes available earliest after the data is generated. The terminal device 2 starts data transmission from the resource block acquired in S4 to S5. Therefore, in the following description, the resource block acquired in S4 to S5 may be referred to as a "transmission start resource block".

In S6, the control unit 25 determines whether the transmission start resource block is the first resource block of the K resource blocks in the wireless resource group. Then, when the transmission start resource block is the first resource block, the terminal device 2 repeatedly transmits the data signal and the pilot signal P K times in S7. That is, the control unit 25 controls the buffer 28, the coding / modulation unit 29, the pilot signal generation unit 26, and the multiplexing unit 30 so that the data signal and the pilot signal P are repeatedly transmitted K times. For example, in the example shown in FIG. 7, when the first resource block in the radio resource group in the time slot T1 is the transmission start resource block, the first to fourth resources in the radio resource group in the time slot T1 are Using the block, the data signal and the pilot signal P are repeatedly transmitted four times. If the transmission start resource block is not the first resource block, the process of the control unit 25 proceeds to S11.

In S11, the control unit 25 identifies the position of the transmission start resource block. That is, the number of resource blocks of the K resource blocks in the radio resource group is specified as the transmission start resource block. In the following description, it is assumed that the transmission start resource block is the kth resource block of the K resource blocks. Therefore, k is any of 2 to K.

In S12, the terminal device 2 repeatedly transmits the data signal and the pilot signal P K−k + 1 times. That is, the control unit 25 controls the buffer 28, the coding / modulation unit 29, the pilot signal generation unit 26, and the multiplexing unit 30 so that the data signal and the pilot signal P are repeatedly transmitted K−k + 1 times.

In S13, the pilot signal generator 26 cyclically shifts the sequence of the pilot signal P by α to generate the pilot signal P2. The cyclic shift amount α is given from the control unit 25. The cyclic shift amount α is determined using the HARQ process ID, for example, as described with reference to FIG. It is assumed that the HARQ process ID of each radio resource group has been notified from the base station 1. That is, the terminal device 2 recognizes the HARQ process ID associated with the radio resource group used by the terminal device 2.

In S14, the control unit 25 waits for the next transmission timing. For example, when the length of the time slot shown in FIG. 10 is P and the length of the radio resource group is K × B, the waiting time in S14 is “P−K × B”.

In S15, the terminal device 2 repeatedly transmits the data signal and the pilot signal P2 k-1 times. That is, the control unit 25 controls the buffer 28, the coding / modulation unit 29, the pilot signal generation unit 26, and the multiplexing unit 30 so that the data signal and the pilot signal P2 are repeatedly transmitted k-1 times.

For example, in the example shown in FIG. 7, it is assumed that the third resource block of the time slot T1 is the transmission start resource block. That is, k = 3. In this case, since K = 4, K−k + 1 is 2 in S12. Then, in the time slot T1, the data signal and the pilot signal P are repeatedly transmitted twice. Then, in S15, k-1 is 2. Therefore, in the time slot T2, the data signal and the pilot signal P2 are repeatedly transmitted twice. As a result, the data signal is repeatedly transmitted four times.

In this way, when the transmission start resource block is the first resource block in the wireless resource group, the data signal is repeatedly transmitted K times in S7. If the transmission start resource block is not the first resource block in the radio resource group, the data signal is repeatedly transmitted K−k + 1 times in S13 and the data signal is repeatedly transmitted k−1 times in S15. Also, the data signal is repeatedly transmitted K times. That is, the number of repetitions of data transmission does not depend on the timing at which the data signal is generated in the terminal device 2. Therefore, the data transmission characteristics in wireless communication are stable.

Further, when the transmission start resource block is not the first resource block in the radio resource group, the pilot signal P is transmitted together with the data signal in S12, and the pilot signal P2 is transmitted together with the data signal in S15. Here, the pilot signal P2 is generated by cyclically shifting the pilot signal P by α. α is determined based on the HARQ process ID associated with the data transmission of S12 and the HARQ process ID associated with the data transmission of S15. Therefore, the receiving device (that is, the base station 1) can identify the HARQ process ID of one by detecting the shift amount between the pilot signal P and the pilot signal P2.

16 to 17 are flowcharts showing an example of processing of the base station 1. The process of this flowchart is executed, for example, when the terminal device 2 is connected to the base station 1. Further, in this embodiment, each radio resource group is assumed to be composed of K resource blocks.

In S21, the wireless resource management unit 46 allocates a wireless resource group to the terminal device 2. The wireless resource information indicating this wireless resource group is notified to the terminal device 2.

In S22, the control unit 45 waits for the set time of the wireless resource group assigned to the terminal device 2. Then, when the current time reaches the set time of the wireless resource group, the process of the control unit 45 proceeds to S23.

Note that the wireless resource group is set in a predetermined cycle as described above. Further, a HARQ process ID is associated with each radio resource group in advance. Therefore, the control unit 45 identifies the HARQ process ID of the radio resource group corresponding to the current time in S23. In the following description, the specified HARQ process ID is “Y”. In addition, the wireless resource group corresponding to the current time may be referred to as a “target wireless resource group”.

At S24, the control unit 45 initializes the variable k to zero. The variable k identifies the resource block within the radio resource group. The wireless resource group is composed of K resource blocks.

At S25, the pilot signal processing unit 42 detects a pilot signal from the received signal. At this time, the pilot signal processing unit 42 attempts to detect the pilot signal P using the replica of the pilot signal P, as described with reference to FIG. Then, when the pilot signal P can detect the pilot signal P from the received signal, the pilot signal processing unit 42 generates link propagation information indicating the characteristics of the wireless link between the terminal device 2 and the base station 1. After that, the demodulation unit 43 demodulates the received signal using the link propagation information, and the decoding unit 44 decodes the output signal of the demodulation unit 43. That is, the received signal is demodulated and decoded using the pilot signal P.

In S26, the control unit 45 determines whether or not the decoding of the received signal has succeeded. Then, when the decoding of the received signal is successful, the base station 1 processes the received data in S41 in association with the HARQ process ID = Y. Further, the control unit 45 stops the decoding process for the remaining resource blocks in the target radio resource group in S44.

When the decoding of the received signal fails (S26: No), the process of the base station 1 proceeds to S27. In S27, the pilot signal processing unit 42 detects the pilot signal P2. Further, the pilot signal processing unit 42 detects the cyclic shift amount α between the pilot signal P and the pilot signal P2. The cyclic shift amount α and the pilot signal P2 are detected by, for example, the method shown in FIG.

In S28, the pilot signal processing unit 42 uses the pilot signal P2 to generate link propagation information indicating the characteristics of the wireless link between the terminal device 2 and the base station 1. After that, the demodulation unit 43 demodulates the received signal using the link propagation information, and the decoding unit 44 decodes the output signal of the demodulation unit 43. That is, the received signal is demodulated and decoded using the pilot signal P2.

At S29, the control unit 45 determines whether or not the decoding of the received signal has succeeded. Then, when the decoding of the received signal is successful, the base station 1 identifies the HARQ process ID associated with the target radio resource group in S42 based on the cyclic shift amount α. In the following description, the HARQ process ID specified in S42 is "Z".

The method of identifying the HARQ process ID based on the cyclic shift amount α follows the rules preset for the terminal device 2 and the base station 1. For example, it is assumed that this rule is “α represents a difference between two HARQ process IDs”. In this case, since Y and α have been obtained in S23 and S27, respectively, Z is calculated. As a result, HARQ process ID = Z is obtained.

In S43, the base station 1 processes the received data in association with the HARQ process ID = Z. Further, the control unit 45 stops the decoding process for the remaining resource blocks in the target radio resource group in S44.

If the decoding of the received signal fails (S29: No), the process of the base station 1 proceeds to S30. In S30, the control unit 45 increments the variable k by 1. In S31, the control unit 45 determines whether or not the variable k has reached K. When the variable k is smaller than K, the process of the base station 1 returns to S25. In this case, the above process is executed for the next resource block in the target radio resource group. On the other hand, if the variable k has reached K, the process of the base station 1 returns to S22. In this case, the above process is executed for the next wireless resource group.

In this way, when the pilot signal P2 is transmitted together with the data signal, the base station 1 detects the cyclic shift amount α between the pilot signal P and the pilot signal P2, and based on the value of α, the HARQ process is performed. Identify the ID. Therefore, even when the data signal is repeatedly transmitted using a plurality of radio resource groups, the base station 1 can identify the HARQ process ID associated with the received data.

For example, as shown in FIG. 7, the data signal and pilot signal P are transmitted using the third and fourth resource blocks in time slot T1, and the data and pilot signals P are transmitted using the first and second resource blocks in time slot T2. It is assumed that the signal and the pilot signal P2 are transmitted. Then, the radio resource group set in the time slot T2 is assumed to be the target radio resource group. The HARQ process ID1 is associated with the radio resource group set in the time slot T1, and the HARQ process ID2 is associated with the radio resource group set in the time slot T2.

In this case, in S23, "ID2" is specified as the HARQ process ID corresponding to the target wireless resource group. However, since the pilot signal P2 is transmitted at time strulo T2, the decoding process of S25 fails. Therefore, the process of the base station 1 proceeds to S27. That is, the shift amount α and the pilot signal P2 are detected in S27, and the data signal is decoded using the pilot signal P2 in S28. In this embodiment, it is assumed that the decoding process of S28 is successful.

Here, when the decoding using the pilot signal P2 is successful, the following situation is assumed.
(1) The received data signal is a data signal transmitted in the second and subsequent data transmissions. (2) The first data transmission is performed using a radio resource group temporally preceding the target radio resource group. Was

In the example shown in FIG. 7, the received data signal is transmitted in the third data transmission. The first data transmission is executed within the time slot T1. Here, the terminal device 2 may manage or control the communication process using the HARQ process ID of the radio resource group in which the first data transmission was performed. Therefore, the base station 1 is also required to specify the HARQ process ID of the radio resource group in which the first data transmission was performed.

Specifically, in S42, the HARQ process ID of the radio resource group in which the first data transmission was performed is specified based on the shift amount α. For example, when the shift amount α represents the difference between ID1 and ID2, the base station 1 can calculate ID1 from the shift amount α and ID2. In this case, the base station 1 can also manage or control the communication process with ID1 (that is, the HARQ process ID of the radio resource group in which the first data transmission was performed).

As described above, according to the embodiment of the present invention, even when a data signal is repeatedly transmitted over a plurality of communication processes in a wireless communication system adopting a grant-free method, the first data transmission is involved. The communication process can be specified. Therefore, regardless of the timing at which the data is generated in the transmission device, the data transmission can be executed a predetermined number of times at all times. As a result, stable data transmission characteristics (for example, decoding success rate in the receiving device) are realized.

1 Base Station 2 Terminal Device 24 Transmission Unit 25 Control Unit 26 Pilot Signal Generation Unit 42 Pilot Signal Processing Unit 45 Control Unit

Claims

A transmitter that transmits a data signal using the first radio resource and the second radio resource;
A second reference signal transmitted with the data signal using the second radio resource is associated with a parameter related to the first reference signal transmitted with the data signal using the first radio resource. A control unit that generates the first reference signal and the second reference signal so as to have a predetermined shift amount;
A wireless transmission device comprising:
The wireless transmission device according to claim 1, wherein the second wireless resource is set at a time different from that of the first wireless resource.
The wireless transmission device according to claim 1, wherein the data signal is repeatedly transmitted using the first wireless resource and the second wireless resource.
The parameter related to the first reference signal is a variable in a generation formula of a code string forming the first reference signal, or a position at which the first reference signal is arranged. The wireless transmission device according to claim 1.
5. The control unit generates the second reference signal by cyclically shifting a code sequence forming the first reference signal by a predetermined shift amount. The wireless transmission device according to one.
The control unit identifies first identification information for identifying a communication process for transmitting the data signal using the first radio resource or a communication process for transmitting the data signal using the second radio resource. The wireless transmission device according to any one of claims 1 to 5, wherein at least one of the second identification information to be associated is associated with the shift amount.
The wireless communication device according to claim 6, wherein the identification information for identifying the communication process is a HARQ process ID.
The wireless transmission device according to claim 6, wherein the control unit associates the difference between the first identification information and the second identification information with the shift amount.
The wireless transmission device according to claim 6, wherein the control unit associates the first identification information with the shift amount.
A radio receiving apparatus for receiving a data signal transmitted using a first radio resource and a second radio resource,
A reference signal processing unit for detecting the reference signal from the received signal,
The second reference signal transmitted together with the data signal using the second radio resource has a predetermined shift amount with respect to the first reference signal transmitted together with the data signal using the first radio resource. The reference signal processing section detects the shift amount.
The radio receiving apparatus according to claim 10, wherein the predetermined shift amount is an amount of cyclic shift performed on a code string forming the first reference signal.
Further comprising a control unit that specifies identification information that identifies a communication process that transmits the data signal,
The shift amount is the data obtained by using the first identification information or the second radio resource for identifying the communication process for transmitting the data signal using the first radio resource at the transmission source of the data signal. Associated with at least one of second identification information identifying a communication process transmitting a signal,
When the wireless reception device receives the data signal transmitted using the second wireless resource, the control unit specifies the second identification information and the shift amount in the first identification information. The wireless receiving device according to claim 10 or 11, characterized in that
The wireless reception device according to claim 12, wherein the identification information for identifying the communication process is a HARQ process ID.
A wireless transmission device that transmits a data signal using the first wireless resource and the second wireless resource;
A wireless reception device for receiving a data signal transmitted from the wireless transmission device,
The wireless transmission device,
Transmitting a first reference signal with the data signal using the first radio resource,
First identification information for identifying a communication process for transmitting the data signal using the first radio resource or second identification for identifying a communication process for transmitting the data signal using the second radio resource Determine the shift amount based on at least one of the information,
A second reference signal is generated by cyclically shifting the code sequence forming the first reference signal by the shift amount,
Transmitting the second reference signal together with the data signal using the second radio resource,
The wireless receiving device,
When the data signal is transmitted by the wireless transmission device using the first wireless resource, the data signal is processed in association with the first identification information,
When the data signal is transmitted by the wireless transmission device using the second wireless resource, the shift amount is detected, and the first identification information is specified from the second identification information and the shift amount. Then, the wireless communication system is characterized by processing the data signal in association with the first identification information.