WO2021250732A1 - Communication device, communication method, and communication system - Google Patents

Abstract

COMMUNICATION DEVICE, COMMUNICATION METHOD, AND COMMUNICATION SYSTEM The communication device supports the D2D communication. This communication device comprises a first decoder and a second decoder. The first decoder decodes a control signal received through a sidelink from another communication device. The second decoder decodes, on the basis of the control signal decoded by the first decoder, a data signal received through the sidelink from the other communication device. When the communication device is in a first state, the first decoder decodes some predetermined resources among resources to which the control signal is mapped and detects a wakeup signal. When the wakeup signal instructs a transition from the first state to a second state, the first decoder starts to decode the control signal.

Description

Communication equipment, communication methods, and communication systems

The present invention relates to a communication device, a communication method, and a communication system.

Currently, most of the network resources are occupied by the traffic used by mobile terminals (including smartphones or future phones). In addition, the traffic used by mobile terminals is expected to continue to increase.

On the other hand, along with the development of IoT (Internet of things) services (for example, monitoring systems for transportation systems, smart meters, devices, etc.), it is required to support services with various requirements. Therefore, in the standard of the 5th generation mobile communication (5G or NR (New Radio)), the standard technology of the 4th generation mobile communication (4G (LTE: Long Term Evolution)) (for example, Non-Patent Documents 1 to 12). ), There is a demand for technology that realizes higher data rates, larger capacities, and lower delays. The 5th generation mobile communication standard is being examined by the working group of 3GPP (Third Generation Partnership Project) (for example, TSG-RAN WG1, TSG-RAN WG2, etc.), and the standard document will be published at the end of 2017. The first edition has been published (for example, Non-Patent Documents 13 to 39).

The 3GPP working group is also discussing V2X (Vehicle to Everything) communication. V2X is V2V (Vehicle to Vehicle) that communicates between automobiles, V2P (Vehicle to Pedestrian) that communicates between automobiles and pedestrians, and V2I (Vehicle to Infrastructure) that communicates between automobiles and road infrastructure. , Includes V2N (Vehicle to Network) that communicates between automobiles and networks. The provision regarding V2X is described in, for example, Non-Patent Document 1. Further, for example, Patent Document 1 describes a method for suppressing power consumption of a terminal device that performs side-link communication.

Furthermore, in the field of wireless communication, repetition transmission may be performed as one of the methods for increasing the reliability of data or the success rate of data reception.

Japanese Unexamined Patent Publication No. 2019-212953

3GPP TS 22.186 V16.2.0 (2019-06) 3GPP TS 36.211 V16.0.0 (2019-12) 3GPP TS 36.212 V16.0.0 (2019-12) 3GPP TS 36.213 V16.0.0 (2019-12) 3GPP TS 36.300 V16.0.0 (2019-12) 3GPP TS 36.321 V15.8.0 (2019-12) 3GPP TS 36.322 V15.3.0 (2019-09) 3GPP TS 36.323 V15.5.0 (2019-12) 3GPP TS 36.331 V15.8.0 (2019-12) 3GPP TS 36.413 V16.0.0 (2019-12) 3GPP TS 36.423 V16.0.0 (2019-12) 3GPP TS 36.425 V15.0.0 (2018-06) 3GPP TS 37.340 V16.0.0 (2019-12) 3GPP TS 38.201 V16.0.0 (2019-12) 3GPP TS 38.202 V16.0.0 (2019-12) 3GPP TS 38.211 V16.0.0 (2019-12) 3GPP TS 38.212 V16.0.0 (2019-12) 3GPP TS 38.213 V16.0.0 (2019-12) 3GPP TS 38.214 V16.0.0 (2019-12) 3GPP TS 38.215 V16.0.1 (2020-01) 3GPP TS 38.300 V16.0.0 (2019-12) 3GPP TS 38.321 V15.8.0 (2019-12) 3GPP TS 38.322 V15.5.0 (2019-03) 3GPP TS 38.323 V15.6.0 (2019-06) 3GPP TS 38.331 V15.8.0 (2019-12) 3GPP TS 38.401 V16.0.0 (2019-12) 3GPP TS 38.410 V16.0.0 (2019-12) 3GPP TS 38.413 V16.0.0 (2019-12) 3GPP TS 38.420 V15.2.0 (2018-12) 3GPP TS 38.423 V16.0.0 (2019-12) 3GPP TS 38.470 V16.0.0 (2019-12) 3GPP TS 38.473 V16.0.0 (2019-12) 3GPP TR 38.801 V14.0.0 (2017-03) 3GPP TR 38.802 V14.2.0 (2017-09) 3GPP TR 38.803 V14.2.0 (2017-09) 3GPP TR 38.804 V14.0.0 (2017-03) 3GPP TR 38.900 V15.0.0 (2018-06) 3GPP TR 38.912 V15.0.0 (2018-06) 3GPP TR 38.913 V15.0.0 (2018-06)

Development of V2P communication is underway as one form of side link communication. In V2P communication, a side link is provided between a communication device mounted on a vehicle (hereinafter, V-UE (Vehicle User Equipment)) and a communication device carried by a pedestrian or the like (hereinafter, P-UE (Pedestrian User Equipment)). Communication takes place. Here, since the P-UE does not know the timing at which the signal is transmitted from the V-UE, it is preferable to constantly monitor the signal transmitted from the V-UE.

However, since P-UE is required to be smaller and lighter, the battery capacity is often small. Therefore, it is required to reduce the power consumption of the P-UE. It should be noted that this request is not limited to V2P communication, and may occur in any D2D communication.

An object relating to one aspect of the present invention is to reduce the power consumption of a communication device that supports D2D communication.

The communication device according to one aspect of the present invention supports D2D (Device-to-Device) communication. This communication device includes a first decoder and a second decoder. The first decoder decodes a control signal received from another communication device via a side link. The second decoder decodes the data signal received from another communication device via the side link based on the control signal decoded by the first decoder. The first decoder decodes a predetermined part of the resources to which the control signal is mapped and detects the wakeup signal when the communication device is in the first state. The first decoder initiates decoding of the control signal when the wakeup signal directs a transition from the first state to the second state.

According to the above aspect, the power consumption of the communication device that supports D2D communication is reduced.

It is a figure which shows an example of the wireless communication system which concerns on embodiment of this invention. It is a figure which shows an example of resource selection based on sensing. It is a figure which shows an example of the reception of a side link signal. It is a figure which shows an example of the receiving operation of the communication apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the transmission method of a wake-up signal. It is a figure which shows an example of the format of the 2nd SCI including a wake-up signal. It is a figure which shows another example of the transmission method of a wake-up signal. It is a figure which shows the 1st scenario of V2V communication and V2P communication. It is a figure which shows the 2nd scenario of V2V communication and V2P communication. It is a figure which shows the 3rd scenario of V2V communication and V2P communication. It is a figure which shows an example of a base station. It is a figure which shows an example of a communication device. It is a flowchart which shows an example of the process of the V-UE which transmits V2X data. It is a flowchart which shows an example of the processing of P-UE which receives V2X data. It is a figure which shows the scenario of V2X communication which concerns on other embodiment.

The issues and examples in this specification are examples, and do not limit the scope of rights of the patent application. For example, even if the expressions described are different, the technology of the present patent application can be applied as long as they are technically equivalent. In addition, the embodiments described in the present specification can be combined within a consistent range.

The terms and technical contents used in this specification are the terms and technical contents described in the specifications (for example, 3GPP TS 38.211 V16.0.0 (2019-12)) or contributions as standards for communication such as 3GPP. May be done.

FIG. 1 shows an example of a wireless communication system according to an embodiment of the present invention. As shown in FIG. 1, the wireless communication system 100 includes a base station 1, a communication device 2, and a communication device 3.

The base station 1 controls cellular communication (uplink / downlink communication via the Uu interface) of the communication device 2 and the communication device 3. That is, the base station 1 receives uplink signals (control signals and data signals) from the communication device 2 and the communication device 3. Further, the base station 1 transmits a downlink signal (control signal and data signal) to the communication device 2 and the communication device 3.

The communication device 2 is mounted on the vehicle in this embodiment. Therefore, in the following description, the communication device 2 may be referred to as "V-UE (Vehicle User Equipment) 2". The V-UE 2 can communicate with another communication device via the base station 1. Further, the V-UE 2 can also communicate with another communication device without going through the base station 1. That is, the V-UE2 supports D2D (Device-to-Device) communication. For example, V2V communication is performed between V-UE2a and V-UE2b. D2D communication, for example, transmits a signal via the PC5 interface. Note that D2D communication is sometimes called "side link communication".

In this embodiment, the communication device 3 is carried by a pedestrian. Therefore, in the following description, the communication device 3 may be referred to as "P-UE (Pedestrian User Equipment) 3". The P-UE 3 can communicate with another communication device via the base station 1. Further, the P-UE 3 can also communicate with another communication device without going through the base station 1. That is, the P-UE3 also supports D2D communication. For example, V2P communication is performed between V-UE2a and P-UE3.

When transmitting data by D2D communication, V-UE2 and P-UE3 determine a resource for transmitting the data. At this time, the V-UE2 and the P-UE3 detect a resource reserved by another communication device in the resource (that is, the resource pool) preset for the D2D communication. Then, the V-UE2 and the P-UE3 detect a free resource based on the information representing the resource reservation and the measured interference level, select a resource from the detected free resources, and transmit the data. In the following description, the process of detecting a resource reserved by another communication device in the resource pool for D2D communication may be referred to as "sensing".

FIG. 2 shows an example of resource selection based on sensing. Here, it is assumed that the resource selection trigger is generated in the subframe n. A resource selection trigger corresponds, for example, to an instruction to determine a resource for transmitting data generated by an application implemented in a communication device.

The communication device sets a selection window and a sensing window for the resource selection trigger. The selection window represents the range of resources that can be selected. That is, the communication device can select a resource for transmitting data from the resources in the selection window. When the resource selection trigger is generated in the subframe n, the range of the selection window is the subframe "n + T1, n + T2". The range of the parameters T1 and T2 is set in advance, for example. Alternatively, the range of the parameters T1 and T2 is notified from the base station 1. Then, the communication device determines the parameters T1 and T2 based on the given range.

The sensing window represents the range in which the communication device performs sensing. That is, the communication device senses each resource in the sensing window. Here, the communication device senses, for example, 1000 subframes immediately before the resource selection trigger. In this case, when it is predicted that the resource selection trigger will be generated in the subframe n, the range of the sensing window is the subframe "n-1000, n-1".

In the sensing process, the communication device decodes the control channel (PSCCH: Physical Sidelink Control Channel) transmitted in the sensing window and measures the received power of the corresponding data channel (PSSCH: Physical Sidelink Shared Channel). The PSCCH can transmit side link control information (SCI: Sidelink Control Information) including information related to the reservation of transmission resources. Further, the communication device measures, for example, the received power (RSRP: Reference Signal Received Power) and / or RSSI (Received Signal Strength Indicator) of the reference signal.

In the above sensing, the communication device detects resources reserved by other communication devices (UE1 and UE2 in FIG. 2). Also, the communication device excludes resources reserved by other communication devices from the resources in the selection window. Then, the communication device selects a resource for transmitting data from the remaining resources. The sensing shown in FIG. 2 is described in Release 14 of 3GPP.

However, in the method shown in FIG. 2, since sensing is continuously performed over a long period of time, the power consumption of the communication device increases. On the other hand, in many cases, the battery capacity of the communication device (that is, P-UE) carried by the pedestrian is small. Therefore, it is required to reduce the power consumption for sensing.

Further, in V2P communication, the P-UE periodically (for example, every second) sends a BMS (Basic Safety Message) message to the V-UE, and a V2X message (that is, V-UE and V-UE / P). -Listen to messages sent to and from the UE / Network). However, the P-UE does not know when the V2X message is transmitted. Also, in order to improve security, it is preferable that the P-UE listens to V2X messages at short intervals.

Then, it is preferable that the P-UE always receives and decodes the control channel of the side link. In the example shown in FIG. 3, the P-UE always receives and decodes the PSCCH signal. At this time, the P-UE acquires the side link control information (SCI: Sidelink Control Information) transmitted via the PSCCH. Then, the P-UE receives the data based on the SCI. However, in this case, the P-UE always receives and decodes the control channel of the side link even during the period when the data to be received by itself is not transmitted, so that the power consumption becomes large.

<Embodiment>
FIG. 4 shows an example of the reception operation of the communication device according to the embodiment of the present invention. Specifically, FIG. 4 shows an example of the reception operation of the P-UE 3 in the side link communication.

The P-UE3 normally waits for the activation trigger of V2P communication in the sleep state. In the sleep state, the P-UE3 does not decode the sidelink control channel PSCCH. Here, in the side link communication, data reception is performed based on the SCI transmitted via the PSCCH. Therefore, in the sleep state in which the PSCCH is not decoded, the P-UE3 also does not decode the side link data channel PSSCH. That is, in the sleep state, the P-UE 3 substantially does not perform side link communication. However, it is preferable that the P-UE 3 continues the cellular communication with the base station 1 even in the sleep state.

The activation trigger is realized by the wakeup signal transmitted from V-UE2. The wake-up signal is not particularly limited, but in this embodiment, one bit of information is transmitted. In this case, for example, "1" represents "wakeup" and "0" represents "non-wakeup (sleep)".

When the V-UE2 detects the P-UE3, it transmits a "wakeup signal: 1" to the P-UE3. At this time, if it is possible to recognize whether or not the P-UE3 is in the sleep state, the V-UE2 transmits a "wakeup signal: 1" to the P-UE3 in the sleep state. The position and state of the P-UE3 may be notified from the base station 1 to the V-UE2, for example. In this case, the information representing the position and state of the P-UE3 is transmitted from the base station 1 to the V-UE2 via, for example, the downlink control channel PDCCH.

The P-UE3 decodes only the wakeup signal in the sleep state. When the wakeup signal is not "1", the P-UE3 continues in the sleep state. On the other hand, if the wakeup signal is "1", the P-UE 3 starts side link communication. That is, the P-UE 3 starts decoding the PSCCH. Then, the P-UE 3 receives data based on the SCI transmitted via the PSCCH.

In this way, when the V-UE2 transmits data to the P-UE3, it transmits a "wakeup signal: 1" to the P-UE3. As a result, the state of the P-UE 3 shifts from the sleep state to the operating state. In other words, when the wakeup signal is not transmitted from the V-UE2, the P-UE3 is in the sleep state and does not decode the PSCCH and the PSCH. That is, the P-UE 3 does not decode the PSCCH and the PSCH when the data to be received by itself has not been transmitted. Therefore, the power consumption of the P-UE 3 is reduced.

FIG. 5 shows an example of a method of transmitting a wakeup signal. In this embodiment, it is assumed that the slot is used for side link communication. The slot length is selected from, for example, Ls, Ls / 2, Ls / 4, and Ls / 8 when the subframe length is Ls. Also, in this example, the slot is composed of 14 symbols.

The symbols S0 and S11 of each slot are used as AGC (Auto Gain Control) symbols. The symbols S10 and S13 are used as gap symbols. The side link feedback channel PSFCH (Physical Sidelink Feedback Channel) is mapped to the symbol S12. The PSFCH is used, for example, for a communication device that has received a sidering signal to transmit an ACK / NACK signal. The side link control channel PSCCH is mapped to some subchannels of symbols S1 to S3 and some subchannels of symbols S4. The side link data channel PSCH is mapped to other resources in each slot.

The control information SCI related to the side link communication is composed of the first SCI and the second SCI in this example. In this case, the first SCI is mapped to the symbols S1 to S3, and the second SCI is mapped to the symbol S4. Then, the wake-up signal is set in the second SCI.

FIG. 6 shows an example of the format of the second SCI including the wakeup signal. In this example, the second SCI includes a layer 1 source ID, a layer 1 destination ID, a HARQ process ID, NDI, RVID, a zone ID (for Distance based feedback), a feedback range, and HAQR ACK / NACK feedback information. include. The CRC is calculated based on the above information. Then, in the embodiment of the present invention, the second SCI includes a 1-bit wakeup signal in addition to the above information.

In the case shown in FIG. 5, V2P communication is performed in units of four slots. For example, it is assumed that V2P communication is performed using slots # 0 to # 3. In this case, the V-UE2 uses, for example, slot # 0 to transmit a wakeup signal. Specifically, when the P-UE3 is activated, the V-UE2 sets “1” in the bit representing the wakeup signal in slot # 0.

The P-UE3 monitors slot # 0 in the sleep state and decodes only the wakeup signal. At this time, the P-UE 3 does not decode other signals transmitted by the PSCCH in slot # 0. Further, P-UE3 does not decode the PSCCH of slots # 1 to # 3. Then, if the wake-up signal represents "1", the state of the P-UE 3 shifts from the sleep state to the operating state. That is, the P-UE3 starts decoding all the signals of the PSCCH.

FIG. 7 shows another example of the method of transmitting the wakeup signal. In this embodiment, the wakeup signal is transmitted using the sidelink feedback channel PSFCH. Here, as shown in FIG. 7, the PSFCH is set every 1 slot, every 2 slots, or every 4 slots. Then, the wake-up signal is set to each PSFCH, for example. Alternatively, in order to reduce the power consumption of the P-UE, the wakeup signal may be set at intervals of 4 slots or more. The position where the wake-up signal is set is determined in advance, or is notified from the base station 1 by PDCCH or RRC.

In the sleep state, the P-UE3 does not decode the PSCCH of each slot, but decodes only the PSFCH for which the wakeup signal is set. At this time, the P-UE 3 does not need to decode the entire PSFCH, but only needs to decode the wake-up signal. Then, if the wake-up signal represents "1", the state of the P-UE 3 shifts from the sleep state to the operating state. That is, the P-UE3 starts decoding all the signals of the PSCCH.

The wakeup signal may be transmitted individually to each P-UE, or may be transmitted to a UE group including a plurality of P-UEs. In the method of transmitting the wakeup signal for each P-UE, the number of bits to be decoded by the P-UE is small (1 bit in the above example), so that the reception performance is improved. That is, the P-UE can decode the wakeup signal even when the radio wave environment is not good. On the other hand, in the method of transmitting the wakeup signal to the UE group including a plurality of P-UEs, since the 1-bit wakeup signal is transmitted to the plurality of P-UEs, the resource of PSCCH per UE. Is reduced. However, if there are multiple groups in the wireless system, it is necessary to send information that identifies the groups.

The size of the side link control information SCI including the wakeup signal may be the same as that of other SCIs. However, in this case, it is preferable that the SCI including the wakeup signal can be distinguished from another SCI by the CRC calculation.

FIG. 8 shows a first scenario of V2V communication and V2P communication. In this scenario, data D is transmitted from V-UE2a to V-UE2b and P-UE3. The V-UE2a is a communication device mounted on the vehicle. The V-UE2b is a communication device mounted on another vehicle. The P-UE3 is a communication device carried by a pedestrian. The data D is not particularly limited, but is, for example, a BSM (Basic Safety Message) message.

Further, in this scenario, it is assumed that the base station 1 recognizes the position and state of each communication device in the cell. That is, the base station 1 recognizes that the V-UE2a, V-UE2b, and P-UE3 exist in the cell. In addition, the base station 1 recognizes whether or not the P-UE 3 is in the sleep state. In this example, it is assumed that the P-UE 3 is in the sleep state. It should be noted that the base station 1 can acquire information indicating the position and state of each communication device by cellular communication with each communication device in the cell.

When the V-UE2a transmits the data D to the V-UE2b, the V-UE2a detects that the sleeping P-UE3 exists in the vicinity of the V-UE2a by communicating with the base station 1. Then, as shown in FIG. 8A, the V-UE2a transmits the data D to the V-UE2b and transmits the wakeup signal to the P-UE3. At this time, the value of the wake-up signal is "1". The data D and the wakeup signal are transmitted simultaneously using two different channels. Specifically, as shown in FIG. 8B, the data D is transmitted via the data channel PSCH and the wakeup signal is transmitted via the control channel PSCCH.

V-UE2b receives the data D and saves it in the memory. The P-UE3 decodes the wakeup signal in the sleep state. In this embodiment, since the wake-up signal is "1", the state of the P-UE 3 shifts from the sleep state to the operating state. Therefore, thereafter, the P-UE 3 decodes the PSCCH.

Subsequently, the V-UE2a transmits the data transmitted to the V-UE2b in FIG. 8A to the P-UE3. That is, the V-UE2a retransmits the data D as shown in FIG. 8C. At this time, the P-UE 3 is in an operating state. Therefore, the P-UE 3 can receive the data D. Further, the V-UE 2b synthesizes the received data D and the newly received data D in FIG. 8A. This improves the reliability of the received data in the V-UE2b.

Thus, in the first scenario, data transmission to the V-UE and a start instruction to the P-UE are performed at the same time. Further, the data transmission to the P-UE acts as a repetitive transmission to the V-UE. Therefore, more efficient side-link communication is realized.

FIG. 9 shows a second scenario of V2V communication and V2P communication. In this scenario, the V-UE2a transmits data D to the V-UE2b, as shown in FIG. 9A. Subsequently, the V-UE2a transmits a wakeup signal to the P-UE3 as shown in FIG. 9B. Then, the wake-up signal shifts the state of the P-UE 3 from the sleep state to the operating state.

After that, the V-UE2a transmits the data transmitted to the V-UE2b in FIG. 9A to the P-UE3. That is, the V-UE2a retransmits the data D as shown in FIG. 9C. At this time, the P-UE 3 is in an operating state. Therefore, the P-UE 3 can receive the data D. Further, the V-UE 2b synthesizes the received data D and the newly received data D in FIG. 9A. This improves the reliability of the received data in the V-UE2b. The second scenario is effective, for example, when the presence of the sleeping P-UE is recognized immediately after the V-UE transmits data to another V-UE.

FIG. 10 shows a third scenario of V2V communication and V2P communication. In this scenario, the V-UE2a transmits a wakeup signal to the P-UE3, as shown in FIG. 10 (a). Then, the wake-up signal shifts the state of the P-UE 3 from the sleep state to the operating state.

Subsequently, the V-UE2a transmits data D to the V-UE2b and the P-UE3 as shown in FIG. 10 (b). At this time, the P-UE 3 is in an operating state. Therefore, the P-UE 3 can receive the data D. Further, the V-UE2a retransmits the data D to the V-UE2b and the P-UE3 as shown in FIG. 10 (c). Then, the V-UE 2b synthesizes the received data D and the newly received data D in FIG. 10 (b). Similarly, the P-UE 3 also synthesizes the received data D and the newly received data D in FIG. 10 (b). That is, in this scenario, the reliability of the received data is improved in both V-UE2b and P-UE3.

In the example shown in FIG. 10, the number of times of repeating data transmission is 2, but data transmission may be performed 3 times or more. Further, even in the cases shown in FIGS. 8 and 9, data transmission may be repeated.

FIG. 11 shows an example of a base station. As shown in FIG. 11, the base station 1 includes an RF receiver 11, a CP removal unit 12, an FFT unit 13, a channel separation unit 14, a data signal demodulator 15, a decoder 16, a control signal demodulator 17, a decoder 18, and communication. It has a processing unit 19, a control signal generation unit 20, an IFFT unit 21, a CP addition unit 22, and an RF transmitter 23. The base station 1 may have other functions not shown in FIG.

The RF receiver 11 receives the uplink cellular signal transmitted from the communication devices 2 and 3. The CP removing unit 12 removes a cyclic prefix (CP: Cyclic Prefix) from the cellular signal received by the RF receiver 11. The FFT unit 13 executes a fast Fourier transform on the received signal to generate a frequency domain signal. The channel separation unit 14 separates the received signal into a data signal and a control signal in the frequency domain.

The data signal demodulator 15 demodulates the received data signal. The decoder 16 decodes the demodulated data signal and reproduces the data. The control signal demodulator 17 demodulates the received control signal. The decoder 18 decodes the demodulated control signal and reproduces the control information.

The communication processing unit 19 includes a D2D communication scheduler and generates a resource allocation instruction for D2D communication based on the control information reproduced by the decoder 18. Further, the communication processing unit 19 manages the position and state of the communication device in the cell. In the example shown in FIG. 1, the communication processing unit 19 has information indicating that the V-UE2a, V-UE2b, and P-UE3 are located in the cell of the base station 1, and whether or not the P-UE3 is in the sleep state. Manage the information that represents. Further, the communication processing unit 19 can generate a wake-up signal in another embodiment described later. The communication processing unit 19 is realized by, for example, a processor system including a processor and a memory.

The control signal generation unit 20 generates a control signal for controlling the communication devices 2 and 3 based on the signal or information generated by the communication processing unit 19. The base station 1 includes a data signal generation unit that generates a data signal, but is omitted in FIG. 11. The IFFT unit 21 executes an inverse fast Fourier transform on the control signal and the data signal to generate a time domain signal. The CP addition unit 22 adds a cyclic prefix to the time domain signal output from the IFFT unit 21. The RF transmitter 23 transmits a cellular signal via the antenna.

FIG. 12 shows an example of communication devices 2 and 3. The communication devices 2 and 3 correspond to V-UE2 or P-UE3 in the example shown in FIG. Further, the communication devices 2 and 3 support cellular communication and D2D communication. The communication devices 2 and 3 may have other functions not shown in FIG.

As shown in FIG. 12, the communication devices 2 and 3 have a traffic processing unit 31, a channel encoder 32, an IFFT unit 33, a CP addition unit 34, an RF transmitter 35, and an RF receiver 36 in order to support cellular communication. It has a channel demodulator 37.

The traffic processing unit 31 generates a traffic to be transmitted by cellular communication. The channel encoder 32 encodes the traffic output from the traffic processing unit 31. The IFFT unit 33 executes an inverse fast Fourier transform on the output signal of the channel encoder 32 to generate a time domain signal. The CP addition unit 34 adds a cyclic prefix to the time domain signal output from the IFFT unit 33. Then, the RF transmitter 35 transmits a cellular signal via the antenna. The cellular signal is received by the base station 1.

The RF receiver 36 receives the cellular signal transmitted from the base station 1. Then, the channel demodulator 37 demodulates the received cellular signal. When the received cellular signal includes a D2D resource allocation instruction, the channel demodulator 37 extracts the D2D resource allocation instruction from the received cellular signal and passes it to the scheduler 41 described later. When the received cellular signal includes information indicating the position or state of the communication devices 2 and 3, the channel demodulator 37 extracts the information from the received cellular signal and passes the information to the scheduler 41.

In order to support D2D communication, the communication devices 2 and 3 include a scheduler 41, a data signal generation unit 42, a control signal generation unit 43, an RF transmitter 44, an RF receiver 45, a data signal demodulator 46, and a data signal decoder. It has 47, a control signal demodulator 48, and a control signal decoder 49.

The scheduler 41 can determine the resource to be used for D2D communication from the resources provided by the wireless communication system or the resources prepared in advance. For example, when the scheduler 41 determines the frequency to be used for D2D communication, the communication devices 2 and 3 perform D2D communication at that frequency. Further, the scheduler 41 can also control the D2D communication of the communication devices 2 and 3 based on the resource allocation instruction received from the base station 1. For example, when the frequency of D2D communication is specified by the resource allocation instruction, the scheduler 41 controls the data generation unit 42 and / or the RF transmitter 44 so that the D2D signal is transmitted at the specified frequency. In addition, the scheduler 41 may control the RF receiver 45 and / or the data signal demodulator 46 to receive the D2D signal at a specified frequency.

The data signal generation unit 42 generates D2D data according to the control by the scheduler 41. The control signal generation unit 43 generates a D2D control signal. In the V-UE2, the control signal generation unit 43 includes a wakeup signal generation unit 43a. When the wake-up signal generation unit 43a detects the presence of the sleeping P-UE3, the wake-up signal generation unit 43a generates "wake-up signal: 1". The RF transmitter 44 transmits a D2D signal (including a D2D data signal, a D2D control signal, and a wakeup signal) via an antenna.

The RF receiver 45 receives a D2D signal (including a D2D data signal, a D2D control signal, and a wakeup signal) transmitted from another communication device. The data signal demodulator 46 demodulates the received D2D data signal. The data signal decoder 47 decodes the output signal of the data signal demodulator 46.

The control signal demodulator 48 demodulates the received D2D control signal. The control signal decoder 49 decodes the output signal of the control signal demodulator 48. As a result, the side link control channel PSCCH is decoded and the side link control information SCI is reproduced. In the P-UE3, the control signal decoder 49 includes a wakeup signal detection unit 49a. The wake-up signal detection unit 49a detects a wake-up signal by decoding a predetermined part of the resources to which the D2D control signal is mapped. The "predetermined part of the resource" is a part of the second SCI in the example shown in FIGS. 5 to 6 and corresponds to a predetermined subchannel of the symbol S4. In the example shown in FIG. 7, the "predetermined part of the resource" is part of the sidelink feedback channel PSFCH.

In the sleep state P-UE3, only the wakeup signal detection unit 49a operates in the control signal decoder 49. That is, in the sleep state P-UE3, among the received D2D control signals, only a predetermined part of the resources to which the D2D control signal is mapped is decoded. When "wake-up signal: 1" is obtained by this decoding process, the state of the P-UE 3 shifts from the sleep state to the operating state, and the control signal decoder 49 decodes the entire D2D control signal. When "Wake-up signal: 0" is obtained, the state of P-UE3 is kept in the sleep state.

The scheduler 41, the data signal generator 42, the control signal generator 43, the data signal demodulator 46, the data signal decoder 47, the control signal demodulator 48, and the control signal decoder 49 are processor systems including a processor and a memory. It may be realized. Alternatively, the scheduler 41, the data signal generator 42, the control signal generator 43, the data signal demodulator 46, the data signal decoder 47, the control signal demodulator 48, and the control signal decoder 49 may be realized by a hardware circuit. good.

FIG. 13 is a flowchart showing an example of processing of V-UE2 for transmitting V2X data. The process shown in FIG. 13 is performed by the V-UE 2a in the examples shown in FIGS. 8 to 10.

In S1, the V-UE2a determines whether or not a sleeping P-UE exists in the vicinity of the V-UE2a. Information indicating whether or not a sleeping P-UE exists in the vicinity of the V-UE2a is notified from the base station 1 to the V-UE2a, for example. Then, when the sleeping P-UE does not exist in the vicinity of the V-UE2a, the V-UE2a transmits the data D to the V-UE2b in S2.

When the sleeping P-UE3 exists in the vicinity of the V-UE2a, in S3, the V-UE2a transmits a wakeup signal to the P-UE3 and data D to the V-UE2b. For example, in the case shown in FIG. 8, the wakeup signal and the data D are transmitted simultaneously via different channels. In the case shown in FIG. 9, the data signal D is transmitted, and then the wakeup signal is transmitted.

In S4, the V-UE2a retransmits the data D. At this time, the data D reaches V-UE2b and P-UE3. That is, the V-UE2b receives the data D twice. Therefore, the V-UE2b can synthesize the data D. Further, in the case shown in FIG. 10, the P-UE3 also receives the data D twice. In this case, the P-UE 3 can also synthesize the data D.

FIG. 14 is a flowchart showing an example of processing of P-UE3 that receives V2X data.

In S11, the P-UE3 determines whether or not its own state is the sleep state. When it is in the sleep state, the P-UE 3 decodes the wake-up signal in S12. At this time, the control signal decoder 49 does not need to decode other resources of the side link control channel PSCCH. It should be noted that the resource to which the wakeup signal is mapped shall be predetermined as shown in FIG. 5 or FIG.

In S13, the P-UE3 determines whether or not the wakeup signal indicates an activation instruction. For example, when the wake-up signal is 1 bit, "1" represents a start instruction and "0" does not represent a start instruction. Then, if the wake-up signal does not indicate an activation instruction, the processing of the P-UE 3 returns to S12. That is, during the period when the activation instruction is not given from another communication device (for example, V-UE2a), the P-UE3 decodes only the wakeup signal.

When the wake-up signal indicates an activation instruction, the state of P-UE3 shifts from the sleep state to the operating state in S14. At this time, the P-UE 3 may notify the base station 1 that the state has changed via the PUCCH (Physical Uplink Control Channel). After this, the P-UE3 decodes the PSCCH in S15. The PSCCH transmits the side link control information SCI. Therefore, the P-UE3 can receive V2X data based on the SCI.

If SCI is not detected continuously from PSCCH for a predetermined time or longer in S16, the processing of P-UE3 proceeds to S17. In S17, the state of P-UE3 shifts from the operating state to the sleep state. At this time, the P-UE 3 may notify the base station 1 via the PUCCH that the state has changed. After that, the processing of P-UE3 returns to S12.

As described above, in the communication method according to the embodiment of the present invention, the communication device in the sleep state does not decode all the resources of the side link control channel, but decodes only the wakeup signal. Then, when the wake-up signal represents an activation instruction, the communication device decodes all the signals of the side link control channel. Therefore, the power consumption of the communication device is reduced.

<Other embodiments>
In the above-described embodiment, the wake-up signal is transmitted between the communication devices (V-UE, P-UE). On the other hand, in another embodiment, the wake-up signal is transmitted from the base station 1 to the communication device (P-UE). In another embodiment, each communication device (V-UE, P-UE) is located in the cell of the base station 1.

In the example shown in FIG. 15A, the V-UE2 transmits a scheduling request to the base station 1 when transmitting data to another communication device (here, P-UE3). Base station 1 allocates resources for V2X data transmission in response to a scheduling request. Further, after receiving the scheduling request from the V-UE 2, the base station 1 transmits a wake-up signal indicating an activation instruction to the P-UE 3. The wake-up signal is directly notified from the base station 1 to the P-UE3 by the downlink control channel PDCCH or RRC signaling without going through the V-UE2.

After that, the P-UE3 shifts from the sleep state to the operating state, and decodes the control signal transmitted from another communication device via the side link. The V-UE 2 transmits a control signal representing the resource allocated by the base station 1 to the P-UE 3 via the side link. Further, the V-UE 2 transmits data to the P-UE 3 using the resources allocated by the base station 1.

Note that the base station 1 may collectively transmit a wakeup signal to the plurality of P-UEs by using the group common PDCCH set for the UE group including the plurality of P-UEs. Then, the states of the plurality of P-UEs shift from the sleep state to the operating state almost at the same time.

In the example shown in FIG. 15B, the base station 1 has a communication device arrangement in the cell (for example, the position of each communication device, the density of the communication device, the distance between the V-UE and the P-UE, and the like). Gather information about. Then, the base station 1 determines whether or not the P-UE 3 should be activated based on the collected information. For example, when a large number of V-UEs are densely packed, the base station 1 determines that it is preferable that the P-UE 3 can receive the signal transmitted from the V-UE 2. That is, when the density of the V-UE is higher than a predetermined threshold value, the base station 1 transmits a wake-up signal transmission instruction to the V-UE 2 in order to activate the P-UE 3. Alternatively, when the distance between the V-UE 2 and the P-UE 3 is small, the base station 1 determines that it is preferable that the P-UE 3 can receive the signal transmitted from the V-UE 2. That is, when the distance between the V-UE 2 and the P-UE 3 is smaller than a predetermined threshold value, the base station 1 transmits a wake-up signal transmission instruction to the V-UE 2. Then, when the V-UE 2 receives the wake-up signal transmission instruction from the base station 1, the V-UE 2 transmits the wake-up signal to the P-UE 3. Also in this method, since the P-UE is activated only when the P-UE should receive a signal from the V-UE, the power consumption of the P-UE is reduced.

The transmission instruction of the wakeup signal is not particularly limited, but is notified to the V-UE2 by, for example, the downlink control channel PDCCH, group common PDCCH, or RRC signaling. In this case, it is preferable that the resource allocation information and the transmission instruction of the wakeup signal are included in the same DCI (Downlink Control Information).

In the embodiment shown in FIGS. 1 to 15 or another embodiment, data is transmitted from the communication device (V-UE) mounted on the vehicle to the communication device (P-UE) carried by a pedestrian or the like. Although V2P communication has been described, the present invention is not limited thereto. That is, the present invention is applicable to V2X including V2V, V2P, and V2N, and is not limited to reducing the power consumption of the P-UE. For example, in V2V communication, the power consumption of the V2V communication device is reduced. Furthermore, the present invention is not limited to V2X communication, but is widely applied to D2D communication. That is, the present invention can contribute to the reduction of power consumption of any mobile terminal that performs side-link communication.

1 Base station 2 (2a, 2b) Communication device (V-UE)
3 Communication device (P-UE)
19 Communication processing unit 41 Scheduler 42 data signal generation unit 43 control signal generation unit 43a wakeup signal generation unit 44 RF transmitter 45 RF receiver 46 data signal demodulator 47 data signal demodulator 48 control signal demodulator 49 control signal decoder 49 49a Wake-up signal detector 100 Wireless communication system

Claims (12)

A communication device that supports D2D (Device-to-Device) communication.
A first decoder that decodes a control signal received from another communication device via a side link, and
A second decoder that decodes a data signal received from the other communication device via the side link based on the control signal decoded by the first decoder is provided.
The first decoder is
When the communication device is in the first state, a predetermined part of the resources to which the control signal is mapped is decoded to detect the wakeup signal.
A communication device comprising decoding the control signal when the wake-up signal instructs a transition from the first state to the second state. The wake-up signal is set to a predetermined resource in a side link control channel (PSCCH: Physical Sidelink Control Channel) that transmits a control signal for D2D communication.
The communication device according to claim 1, wherein when the communication device is in the first state, the first decoder decodes only the predetermined resource in the side link control channel. The wake-up signal is set to a predetermined resource in the side link feedback channel (PSFCH: Physical Sidelink Feedback Channel) that transmits the feedback signal of D2D communication.
The communication device according to claim 1, wherein when the communication device is in the first state, the first decoder decodes only the predetermined resource in the side link feedback channel. A communication device that supports D2D (Device-to-Device) communication.
A data signal generator that generates a data signal to be transmitted to the second communication device,
A control signal generator that generates a control signal to be transmitted to the third communication device,
A transmission unit for transmitting the data signal and the control signal is provided.
The control signal includes a wake-up signal and includes a wake-up signal.
The wake-up signal represents a transition instruction between a first state of decoding only the wake-up signal and a second state of decoding the control signal.
When the third communication device is in the first state, the control signal generation unit includes a control including a wake-up signal for shifting the third communication device from the first state to the second state. A communication device characterized by generating a signal. The transmission unit simultaneously transmits the data signal and the control signal including the wake-up signal to the second communication device and the third communication device, respectively, and then transmits the data signal to the second communication device and the second communication device and the third communication device, respectively. The communication device according to claim 4, wherein the data is transmitted to the third communication device. The transmitter is
The data signal is transmitted to the second communication device, and the data signal is transmitted to the second communication device.
A control signal including the wake-up signal is transmitted to the third communication device, and the control signal is transmitted to the third communication device.
The communication device according to claim 4, wherein the data signal is transmitted to the second communication device and the third communication device. The transmitter is
A control signal including the wake-up signal is transmitted to the third communication device, and the control signal is transmitted to the third communication device.
The data signal is transmitted to the second communication device and the third communication device, and the data signal is transmitted to the second communication device and the third communication device.
The communication device according to claim 4, wherein the data signal is retransmitted to the second communication device and the third communication device. The communication device according to claim 4, further comprising a detection unit that detects the state of the third communication device based on a control signal transmitted from the base station. A communication method used in a communication system including a plurality of communication devices that support D2D (Device-to-Device) communication.
In the first state, the first communication device decodes a predetermined resource among the resources to which the control signal transmitted from another communication device via the side link is mapped.
The second communication device is a second communication device from the first state, which is mapped to the predetermined resource when the first communication device is in the first state. The control signal including the wake-up signal to shift to the state is transmitted to the first communication device, and the control signal is transmitted to the first communication device.
When the first communication device detects the wakeup signal by decoding the predetermined resource, the first communication device starts decoding the control signal in the second state.
The second communication device is a communication method comprising transmitting data to the first communication device and the third communication device. A communication system including a plurality of communication devices that support D2D (Device-to-Device) communication.
In the first state, the first communication device decodes a predetermined resource among the resources to which the control signal transmitted from another communication device via the side link is mapped.
The second communication device is a second communication device from the first state, which is mapped to the predetermined resource when the first communication device is in the first state. The control signal including the wake-up signal to shift to the state is transmitted to the first communication device, and the control signal is transmitted to the first communication device.
When the first communication device detects the wakeup signal by decoding the predetermined resource, the first communication device starts decoding the control signal in the second state.
The second communication device is a communication system characterized by transmitting data to the first communication device and the third communication device. A communication system including a base station and a plurality of communication devices that support D2D (Device-to-Device) communication.
In the first state, the first communication device does not decode the control signal transmitted from the other communication device via the side link, and does not decode it.
The second communication device transmits a request related to the schedule of data transmission to the first communication device to the base station.
In response to the request, the base station transmits a wake-up signal for shifting the first communication device from the first state to the second state to the first communication device, and at the same time, the first communication device. Notifying the second communication device of the schedule of data transmission to the communication device,
When the first communication device detects the wakeup signal, the first communication device starts decoding the control signal in the second state.
The second communication device transmits a control signal representing a schedule notified from the base station to the first communication device, and transfers data to the first communication device according to the schedule notified from the base station. A communication system characterized by transmitting. A communication system including a base station and a plurality of communication devices that support D2D (Device-to-Device) communication.
In the first state, the first communication device decodes a predetermined resource among the resources to which the control signal transmitted from another communication device via the side link is mapped.
The base station determines whether or not to shift the state of the first communication device from the first state to the second state based on the arrangement of the communication devices in the cell.
When the base station shifts the state of the first communication device from the first state to the second state, the base station changes the first communication device from the first state to the second state. Instructing the second communication device to transmit the wake-up signal to be transferred to the first communication device,
In response to the instruction, the second communication device transmits the control signal including the wakeup signal mapped to the predetermined resource to the first communication device.
A communication system characterized in that, when the first communication device detects the wakeup signal, it starts decoding the control signal in the second state.

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