Synchronization method and communication device

Abstract

Embodiments of this application provide a synchronization method and a communication device. When a low-power communication system such as passive IoT or ambient power-supported IoT is introduced into an NR system, the synchronization signal of the low-power communication system can coexist with the subcarriers of the NR system. This method includes that after generating the synchronization signal, a first device transmits the synchronization signal to a second device. The synchronization signal is generated in an orthogonal frequency division multiplexing (OFDM) mode, the synchronization signal includes a first signal and / or a second signal, the first signal is used to determine the start position of the time domain occupied by the data transmitted from the first device to the second device, and the second signal is used to determine the frequency at which the second device transmits data to the first device.

Description

Technical Field

[0001] This application relates to the field of communications, and more particularly, to a synchronization method and a communication device.

Background Art

[0002] This application claims priority to Chinese Patent Application No. 202210692328.9, titled "SYNCHRONIZATION METHOD AND COMMUNICATION APPARATUS", filed with the China National Intellectual Property Administration on June 17, 2022, the entire content of which is incorporated herein by reference.

[0003] With the development of the Internet of Things (IoT) technology, the service life of IoT terminal devices has become a bottleneck in IoT development. By using low-power communication technology, the power consumption of terminal devices can be reduced, achieving the effect of increasing the service life of terminal devices. Therefore, passive Internet of Things (passive IoT) or ambient power-supported Internet of Things (ambient power-supported IoT) becomes possible.

[0004] Currently, in Release 18 (R18) of the 3rd generation partnership project (3GPP), it is planned that the 5th generation (5G) system or new radio (NR) system will be enabled to support low-power communication systems such as passive IoT or ambient power-supported IoT. However, in the relevant specifications of the synchronization signal of the low-power communication system, the compatibility between the synchronization signal and the NR system is not considered. In this case, when the synchronization signal of the low-power communication system is directly used in the NR system, there is interference between the time-domain waveform of the synchronization signal and the time-domain waveform of the subcarriers of the NR system. Therefore, when a low-power communication system such as passive IoT or ambient power-supported IoT is introduced into the NR system, how to enable the synchronization signal of the low-power communication system to coexist with the subcarriers of the NR system is an urgent issue to be solved currently.

Summary of the Invention

[0005] Embodiments of the present application provide a synchronization method and a communication device. When a low-power communication system such as passive IoT or ambient power-supported IoT is introduced into the NR system, the synchronization signal of the low-power communication system can coexist with the subcarriers of the NR system.

[0006] To achieve the above object, in the embodiments of the present application, the following technical solutions are used.

[0007] According to a first aspect, a synchronization method is provided. This method can be executed by a first device, can be executed by a component of the first device, such as a processor, a chip, or a chip system of the first device, or can be implemented by a logic module or software capable of implementing all or some of the functions of the first device. Hereinafter, an example where the first device executes this method is used for description. This method includes the first device generating a synchronization signal and transmitting the synchronization signal to a second device. The synchronization signal is generated in an orthogonal frequency division multiplexing (OFDM) - like format, and the synchronization signal includes a first signal and / or a second signal. The first signal is used to determine the start position of the time domain occupied by the data transmitted from the first device to the second device, and the second signal is used to determine the frequency at which the second device transmits data to the first device. Since the synchronization signal is generated in an OFDM - like format, the time - domain waveform of the synchronization signal can be a waveform obtained by superimposing a plurality of orthogonal sub - carriers. Therefore, there is an orthogonality relationship between the time - domain waveform of the synchronization signal and the time - domain waveform of the sub - carriers of the NR system. Therefore, when a low - power communication system, such as a passive IoT or an ambient - power - compatible IoT, is introduced into the NR system, the synchronization signal of the low - power communication system can coexist with the sub - carriers of the NR system.

[0008] According to a second aspect, a synchronization method is provided. This method may be executed by a second device, may be executed by a component of the second device, such as a processor, chip, or chip system of the second device, or may be implemented by a logic module or software capable of implementing all or some of the functions of the second device. Hereinafter, an example in which this method is executed by the second device will be used for description. This method includes the second device receiving a synchronization signal from the first device and performing time synchronization and / or frequency synchronization based on the synchronization signal. The synchronization signal is generated in an orthogonal frequency division multiplexing (OFDM) - like format, and the synchronization signal includes a first signal and / or a second signal. The first signal is used to determine a start position occupied by data transmitted from the first device to the second device, and the second signal is used to determine a frequency at which the second device transmits data to the first device. The synchronization signal is generated in an OFDM format, such that the synchronization signal and the OFDM sub - carriers of the data transmitted from the first device to the second device are orthogonal to each other. Further, when receiving the signal, the second device can completely separate the time - domain waveform of the synchronization signal from the time - domain waveform of the OFDM sub - carriers of the data transmitted by the first device to avoid interference. Therefore, when a low - power communication system, such as a passive IoT or an ambient - power - compatible IoT, is introduced into an NR system, the synchronization signal of the low - power communication system can coexist with the sub - carriers of the NR system.

[0009] In relation to the first aspect or the second aspect, in a possible implementation, the synchronization signal includes a first signal and a second signal, and the second signal is arranged after the first signal. Based on this solution, after the second device detects the first signal, the second device can detect the second signal, obtain the time duration of the second signal, and further calculate the BLF in relation to the DR carried in the downlink data.

[0010] In relation to the first or second aspect, in a possible implementation, the first signal and the second signal are arranged in the same OFDM symbol. Based on this solution, after detecting the first signal, the second device may determine to start receiving the second signal.

[0011] In relation to the first or second aspect, in a possible implementation, the waveform of the synchronization signal is a cyclic prefix orthogonal frequency division multiplexing CP - OFDM waveform.

[0012] In relation to the first or second aspect, in a possible implementation, the waveform of the synchronization signal is generated in a CP - OFDM mode based on a first sequence.

[0013] In relation to the first or second aspect, in a possible implementation, the waveform of the synchronization signal is generated in a discrete Fourier transform DFT transform precoding mode.

[0014] In relation to the first or second aspect, in a possible implementation, the fact that the waveform of the synchronization signal is generated in a discrete Fourier transform DFT transform precoding mode includes that the waveform of the synchronization signal is a waveform obtained through CP - OFDM for a second sequence, and the second sequence is a sequence obtained through DFT transform precoding for the first sequence.

[0015] In relation to the first aspect or the second aspect, in a possible implementation, the time-domain resource of the first signal includes the first K time units among the N time units corresponding to the desired signal in one OFDM symbol, where K is a positive integer, and the desired signal in the OFDM symbol is the part other than the cyclic prefix CP in the OFDM symbol. Based on this solution, the second device may first detect the first signal before the second signal and the downlink data, and then receive the downlink data and the second signal. In addition, from the perspective of the utilization of the time-domain resource for transmitting signals, the first signal occupies only some of the time-domain resources of the OFDM symbol. Therefore, the idle time-domain resources of the OFDM symbol can be used for the transmission of other content, such as the second signal, data 0, or RTcal.

[0016] In relation to the first aspect or the second aspect, in a possible implementation, the time-domain resource of the first signal further includes a part of the time units corresponding to the CP in the OFDM symbol where the first signal is located. Based on this solution, if the first signal is a low-level signal, a part of the time units corresponding to the CP is added to the time-domain resource of the first signal, thereby making the duration of the low-level signal long enough. Further, the first signal can be better distinguished from the low-level part of the second signal and / or the low-level part of the downlink data. In this way, when receiving a signal, the second device may determine that the low-level signal having the longest time duration in the received signal is the first signal.

[0017] In relation to the first aspect or the second aspect, in a possible implementation, the signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol in which the first signal is arranged is a low-level signal, the time length of the last S time units is equal to or greater than the time length of the CP in the OFDM symbol in which the first signal is arranged, and the desired signal in the OFDM symbol is the part other than the CP in the OFDM symbol. In other words, it is possible to ensure that the signal carried in the last S time units corresponding to the desired signal in the OFDM symbol in which the first signal is arranged is a low-level signal, thereby ensuring that the level of the CP signal is low. In this way, the duration of the low-level part of the first signal can be increased.

[0018] In relation to the first aspect or the second aspect, in a possible implementation, the time-domain resource of the second signal includes M out of the N time units corresponding to the desired signal in the OFDM symbol, where M is a positive integer, and the desired signal in the OFDM symbol is the part other than the CP in the OFDM symbol.

[0019] In relation to the first aspect or the second aspect, in a possible implementation, the synchronization signal includes the second signal, the waveform of the synchronization signal is generated in a CP-OFDM format by performing DFT transform precoding on the first sequence, the first sequence includes the third sequence, the third sequence is the sequence used to generate the second signal, M satisfies the first condition, the first condition includes that N is L times M and the number of elements included in the first sequence is L times the number of elements included in the third sequence, N is a power of 2, and L is a positive integer.

[0020] In relation to the first aspect or the second aspect, in a possible implementation, M is the maximum value among a plurality of values that satisfy the first condition. Based on this solution, when the second device measures the duration of the second signal by using a clock edge, the measurement error can be reduced.

[0021] In relation to the first aspect, in a possible implementation, this method further includes the first device receiving capability information from the second device, and the capability information includes at least one of whether the second device supports energy harvesting, whether the second device supports envelope detection, or whether the second device supports backscatter communication.

[0022] In relation to the second aspect, in a possible implementation, this method further includes the second device transmitting capability information to the first device, and the capability information includes at least one of whether the second device supports energy harvesting, whether the second device supports envelope detection, or whether the second device supports backscatter communication.

[0023] According to a third aspect, there is provided a communication device configured to implement the various methods described above. This communication device can be the first device in the first aspect, a device including the first device, or a device included in the first device, such as a chip. Alternatively, this communication device can be the second device in the second aspect, a device including the second device, or a device included in the second device. This communication device includes corresponding modules, units, or means for implementing the methods described above. The modules, units, or means can be implemented by hardware, software, or the hardware executing the corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

[0024] In some possible designs, the communication device may include a processing module and a transceiver module. The transceiver module, which may also be referred to as a transceiver unit, is configured to implement a transmission function and / or a reception function in any one of the foregoing aspects and any one of the possible implementations of the foregoing aspects. The transceiver module may include a transceiver circuit, a transceiver machine, a transceiver, or a communication interface. The processing module may be configured to implement a processing function in any one of the foregoing aspects and any one of the possible implementations of the foregoing aspects.

[0025] In some possible designs, the transceiver module includes a transmission module and a reception module, which are each configured to implement a transmission function and a reception function in any one of the foregoing aspects and any one of the possible implementations of the foregoing aspects.

[0026] According to a fourth aspect, a communication device including a processor and a memory is provided. The memory is configured to store computer instructions. When the processor executes the instructions, this communication device is enabled to execute the method in any one of the foregoing aspects. This communication device may be the first device in the first aspect, a device including the first device, or a device included in the first device, such as a chip. Alternatively, this communication device may be the second device in the second aspect, a device including the second device, or a device included in the second device.

[0027] According to a fifth aspect, a communication device including a processor and a communication interface is provided. The communication interface is configured to communicate with a module external to this communication device. The processor is configured to execute a computer program or instructions to enable this communication device to execute the method according to any one of the foregoing aspects. This communication device can be, for example, a chip, which is the first device in the first aspect, a device including the first device, or a device included in the first device. Alternatively, this communication device can be the second device in the second aspect, a device including the second device, or a device included in the second device.

[0028] According to a sixth aspect, a communication device including at least one processor is provided. The processor is configured to execute a computer program or instructions stored in a memory to enable this communication device to execute the method in any one of the foregoing aspects. The memory may be coupled to the processor or may be independent of the processor. This communication device can be, for example, a chip, which is the first device in the first aspect, a device including the first device, or a device included in the first device. Alternatively, this communication device can be the second device in the second aspect, a device including the second device, or a device included in the second device.

[0029] According to a seventh aspect, a computer-readable storage medium is provided. This computer-readable storage medium stores a computer program or instructions. When the computer program or instructions are executed on this communication device, this communication device is enabled to execute the method in any one of the foregoing aspects.

[0030] According to an eighth aspect, a computer program product including instructions is provided. When this computer program product runs on a communication device, the communication device is enabled to execute the method in any one of the foregoing aspects.

[0031] According to a ninth aspect, a communication device (for example, this communication device may be a chip or a chip system) is provided. This communication device includes a processor configured to perform the functions in any one of the foregoing aspects.

[0032] In some possible designs, this communication device includes a memory configured to store necessary program instructions and data.

[0033] In some possible designs, when this device is a chip system, this device may include a chip or may include a chip and another individual component.

[0034] It can be understood that when the communication device provided in any one of the third aspect to the ninth aspect is a chip, the foregoing transmission action / function may be understood as an output, and the reception action / function may be understood as an input.

[0035] Regarding the technical effects brought about by any design in the third aspect to the ninth aspect, reference may be made to the technical effects brought about by various designs in the first aspect or the second aspect. Details will not be described again in this specification.

[0036] According to a tenth aspect, a communication system is provided. This communication system includes a first device in the foregoing aspect and a second device in the foregoing aspect.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Embodiments for Carrying Out the Invention

[0038] To facilitate understanding of the technical solutions provided in the embodiments of the present application, the technologies related to the present application are first briefly described. The brief description is provided hereinafter.

[0039] 1. IoT:

[0040] The Internet of Things (IoT) refers to "the Internet through which things are connected to each other". The IoT extends the user side of the Internet to any object, thereby enabling any object to perform information exchange and communication. Such a communication mode is also called machine type communication (MTC). Communication nodes are called MTC terminals or MTC devices. Typical IoT services include services such as smart grids, environmental monitoring, smart agriculture, and smart meter reading.

[0041] In most cases, it can be known from typical IoT services that a large number of MTC terminals need to be deployed for the IoT. This requires that MTC terminals can be obtained and used at low cost, and also requires that MTC terminals can be used for a long time. However, in most service scenarios, it is not possible to provide external power to a large number of MTC terminals. Therefore, MTC terminals are powered by batteries. Moreover, the limited capacity of the batteries and the power consumption of MTC terminals limit the usage time of MTC terminals. This increases the difficulty and cost of maintaining MTC terminals. In this case, IoT development is restricted.

[0042] To meet the above requirements, low-power communication technologies such as wireless power transmission technology, envelope detection and demodulation technology, or backscatter modulation technology can be used in the IoT. Backscatter communication technology is one of the low-power communication technologies and has characteristics such as low cost and ultra-low power consumption. Therefore, by using backscatter communication technology, the usage time of MTC terminals can be increased.

[0043] 2. Backscatter Communication Technology:

[0044] Backscatter communication technology is a communication technology based on wireless power transmission, envelope detection and demodulation, and backscatter modulation technology. FIG. 1 shows an example of a diagram of the architecture of a backscatter communication system according to an embodiment of the present application. As shown in FIG. 1, the backscatter communication system may include an exciter 101, a receiver 102, and a reflector 103. The communication link of the backscatter communication system includes a downlink and an uplink. The downlink may be a communication link through which the exciter 101 transmits a signal to the reflector 103. The uplink may be a communication link through which the reflector 103 transmits a signal to the receiver 102.

[0045] The exciter 101 and the receiver 102 may be deployed in the same device, or the exciter 101 and the receiver 102 may be separated.

[0046] The reflector 103 can be classified into a passive reflector and a semi-passive reflector according to whether the reflector 103 is powered by a battery. The passive reflector is not powered by a battery. In addition, since the downlink signal transmitted by the exciter 101 is a radio frequency signal, the passive reflector needs to rectify the downlink signal transmitted by the exciter 101, and use the rectified DC signal output as a power source to supply power to the internal circuit of the passive reflector. Since the semi-passive reflector has a battery, the semi-passive reflector does not depend on the downlink signal transmitted by the exciter 101 for power supply.

[0047] For example, in the downlink, the exciter 101 can modulate the downlink signal in an amplitude shift keying (ASK) mode, and the reflector 103 can demodulate the downlink signal by using a low-power-based envelope detector. In the uplink, the reflector 103 can change the load of the antenna based on the information bits to be transmitted, whereby the information bits can be modulated onto the incident carrier (i.e., the downlink signal), and then the downlink signal is reflected to the receiver 102. In this case, wireless transmission of the uplink signal is carried out. In this way, the reflector 103 does not require high-power devices such as radio frequency oscillators, power amplifiers, and low-noise amplifiers, and thereby the backscatter communication system features low cost and ultra-low power consumption.

[0048] In connection with the aforementioned backscatter communication technology, hereinafter, an ultra-high frequency (UHF) radio frequency identification (RFID) system will be used as an example to describe the architecture of a communication system that combines IoT and backscatter communication technology.

[0049] For example, FIG. 2 shows an example of a diagram of the architecture of a UHF RFID system according to an embodiment of the present application. As shown in FIG. 2, the UHF RFID system may include a reader 201 and a tag 202. In a possible implementation, in the UHF RFID system, the exciter 101 and the receiver 102 shown in FIG. 1 are arranged in the same device, that is, the reader 201 may include the exciter 101 and the receiver 102. The tag 202 in the UHF RFID system may be the reflector 103 shown in FIG. 1. The reader 201 and the tag 202 may also be referred to as MTC terminals or MTC devices.

[0050] The communication link of the UHF RFID system also includes a downlink and an uplink. The downlink can be the communication link through which the reader 201 transmits a signal to the tag 202. The uplink can be the communication link through which the tag 202 transmits a signal to the reader 201.

[0051] The reader 201 transmits a downlink signal to the tag 202. The downlink signal can include a downlink excitation signal and data. The downlink excitation signal can be used to provide energy to the tag 202. The data can be used for the transmission of downlink signaling to the tag 202 and can be used by the tag 202 to transmit an uplink signal to the reader 201 by using the backscatter technology. In this way, the reader 201 can identify the identity (ID) of the tag 202 by transmitting a downlink signal and receiving an uplink signal, and can further perform read or write operations on the tag 202.

[0052] For example, the downlink signaling is a Query command. The information carried in the data can include a command word, a divide ratio (DR), a coding scheme, select command configuration parameters, a session layer, etc.

[0053] Note that "data" can be the data that needs to be transmitted from the transmitting end to the receiving end. The data can be called valid data or desired data. In other words, "data", "valid data", or "desired data" can be replaced with each other. This is uniformly described in this specification and will not be described in detail again later.

[0054] 3. Wake-up mechanism-based communication system:

[0055] The wake-up mechanism-based communication system can also reduce the power consumption of MTC terminals and further increase the usage time of MTC terminals. FIG. 3 shows an example of a diagram of the architecture of a wake-up mechanism-based communication system according to an embodiment of the present application. As shown in FIG. 3, the wake-up mechanism-based communication system may include a network device 301 and a terminal device 302. The network device 301 and the terminal device 302 may also be referred to as MTC terminals or MTC devices. In this system, the terminal device 302 may be in a power saving mode (PSM) or a sleep mode. The network device 301 may send a downlink wake-up signal (WUS) to the terminal device 302 in the PSM or sleep mode to notify the terminal device 302 to receive and transmit data. In this way, it is possible to achieve the energy-saving effect of the terminal device 302.

[0056] The network device 301 may be an access network device in an NR system. Alternatively, the network device 301 may be a reader 201 in a UHF RFID system.

[0057] For example, the modulation scheme of the wake-up signal may be on-off keying (OOK) or ASK, whereby the terminal device 302 can demodulate the downlink signal transmitted by the network device 301 based on a low-power envelope detector. In this way, it is possible to reduce the standby power consumption of the terminal device 302 and extend the standby life of the terminal device 302.

[0058] It should be noted that the aforementioned backscatter communication technology can be combined with a wake-up mechanism. For example, tag 202 in FIG. 2 can be in PSM or sleep mode, and reader 201 can send a wake-up signal to tag 202 in PSM or sleep mode to notify tag 202 to send and receive data.

[0059] It should be understood that the aforementioned communication system based on backscatter communication technology and the aforementioned communication system based on wake-up mechanism are usually asynchronous systems. In other words, time synchronization is not performed for reader 201 and tag 202, nor for network device 301 and terminal device 302. Therefore, a preamble or synchronization signal needs to be inserted before the data of the downlink signal, so that tag 202 or terminal device 302 can complete the detection and synchronization of the downlink signal.

[0060] 4. Pulse Interval Encoding (PIE):

[0061] According to the 18000-6C standard of the International Standardization Organization (ISO) or the International Electrotechnical Commission (IEC), the data in the downlink signal of the RFID system is encoded in a PIE format. In PIE, data is defined as "0" or "1" by using different time lengths for high and low levels. FIG. 4 shows examples of PIE symbols for data 0 and PIE symbols for data 1. As shown in FIG. 4, the time length T of data 0 data-0is the type A reference interval (Tari), and the low-level time duration is the pulse width (PW). The time duration T of Data 1 data-1 has a value range of [1.5Tari, 2Tari], and the low-level length is PW. The value range of Tari is [6.25 μs, 25 μs], and the value range of PW is [max(0.265Tari, 2 μs), 0.525Tari], where max() indicates that the maximum value is taken.

[0062] In this embodiment of the present application, it should be noted that the meaning of "time duration" is the same as the meaning of "duration", and both represent the time duration occupied by signals, symbols, levels, etc. in the time domain. In other words, "time duration" and "duration" can be replaced with each other. This is uniformly described in this specification and will not be described in detail again later.

[0063] As described above, in order for tag 202 to be able to complete the detection and synchronization of the downlink signal, a preamble or synchronization signal needs to be inserted before the data of the downlink signal in the RFID system. Correspondingly, how to insert a preamble or synchronization signal before the data of the downlink signal is specified in the ISO / IEC 18000-6C standard and will be specifically described later.

[0064] For example, FIG. 5 is a diagram of the frame structure of the downlink signal of the RFID system. The frame structure of the downlink signal of the RFID system may include a frame header 501, downlink data 502, and a check code 503. The frame header 501 is a synchronization signal and is used by the tag 202 to complete the detection and synchronization of the downlink signal. The downlink data 502 is used to carry downlink signaling. The check code 503 is used to detect whether an error has occurred in the data transmission process. The check code 503 may be a 5-bit cyclic redundancy check (CRC) code or a 16-bit CRC code.

[0065] Based on different downlink signaling, the frame header 501 may use a preamble or a Frame-Sync code. For example, when the downlink signaling transmitted by the reader 201 is a query command, the reader 201 may use the preamble as the frame header. When the reader 201 transmits a command other than the query command, the reader 201 may use the frame sync code as the frame header.

[0066] For example, FIG. 6 is a diagram of the PIE symbol in which the preamble is used as the frame header 501. The PIE symbol of the preamble may include a delimiter, data 0, reader-tag calibration (RTcal), and tag-reader calibration (TRcal).

[0067] The delimiter indicates the time-domain start position of the downlink data 502 of the downlink signal. For example, the delimiter is a continuous low-level signal. The time length T delimiter of the delimiter is 12.5 μs, and the tolerance range is within 5%. In other words, the time length T delimiterThe value range of is [0.95×12.5μs, 1.05×12.5μs].

[0068] RTcal can be used as a reference for the tag 202 to decode the PIE symbol. The time duration T of RTcal RTcal is the sum of the time duration Tari of data 0 and the time duration T of data 1. In other words, the value range of the time duration T of RTcal data-1 is [2.5Tari, 3Tari]. RTcal For example, when the time duration of the PIE symbol is less than half of the time duration T of RTcal, the tag 202 may determine that the PIE symbol is data 0. When the time duration of the PIE symbol is greater than half of the time duration T of RTcal, the tag 202 may determine that the PIE symbol is data 1.

[0069] For example, when the time duration of the PIE symbol is less than half of the time duration T of RTcal RTcal the tag 202 may determine that the PIE symbol is data 0. When the time duration of the PIE symbol is greater than half of the time duration T of RTcal RTcal the tag 202 may determine that the PIE symbol is data 1.

[0070] TRcal is used to calculate the uplink backscatter-link frequency (BLF) of the data transmitted by the tag 202 to the reader 201 in relation to DR. DR is carried in the downlink data 502 in the query command. The value of DR can be 8 or 64 / 3. The tag 202 can calculate BLF according to Equation (1).

[0071]

Equation

[0072] T TRcal represents the time duration of TRcal. The value range of T TRcal is [1.1T RTcal , 3T RTcal .

[0073] For example, FIG. 7 is a diagram of a PIE symbol in which a frame synchronization code is used as a frame header 501. The PIE symbol of the frame synchronization code may include a delimiter, data 0, and RTcal. Regarding the configuration of the delimiter, data 0, and RTcal of the PIE symbol of the frame synchronization code, refer to the delimiter, data 0, and RTcal of the PIE symbol of the preamble. Details will not be described again in this specification.

[0074] As described above, a low-power communication system such as a passive IoT or an ambient power-compatible IoT can be a communication system having one of energy harvesting technology, envelope detection and demodulation technology, or backscatter modulation technology. The low-power communication system can be an asynchronous communication system. In other words, the transmission-end device is not strictly synchronized with the reception-end device. Therefore, a related organization such as ISO or IEC defines related specifications related to the synchronization signal in the downlink signal, whereby the reception-end device completes the detection and synchronization of the downlink signal.

[0075] 5. Orthogonal Frequency Division Multiplexing (OFDM):

[0076] Currently, 3GPP supports the use of OFDM technology in the uplink transmission solution and downlink transmission solution of the NR system. OFDM technology is a multi-carrier transmission technology. The principle of OFDM technology is to divide a plurality of sub-channels in the frequency domain, perform serial-parallel conversion on the data to be transmitted to obtain a plurality of groups of data to be transmitted in parallel, and then modulate each group of data to the sub-carriers of each sub-channel for transmission. Therefore, in the time domain, the transmission of the data to be transmitted is performed through a plurality of sub-carriers superimposed in space, and in that space, the plurality of sub-carriers are orthogonal to each other. Furthermore, when the signal is received, the plurality of sub-carriers can be separated, and then each sub-carrier is demodulated to obtain the data to be transmitted.

[0077] 6. Explanation of terms related to the NR system:

[0078] (1) General concept: The time domain of the NR system is the time unit T c =1 / (Δf max ·N f ). Δf max =480×10 3 Hz, and N f =4096. Coefficient κ = T s / T c =64. T s =1 / (Δf ref ·N f,ref ), Δf ref =15×10 3 Hz, and N f,ref =2048.

[0079] (2) Numerology:

[0080] The transmission numerology supported by the NR system is shown in Table 1. In Table 1, the first column is the subcarrier spacing (SCS) configuration μ, the second column represents the subcarrier spacing, and the third column represents the cyclic prefix (CP).

[0081]

Table 1

[0082] The time lengths of the normal CP and the extended CP satisfy

[0083]

Equation

[0084] where

[0085]

Equation

[0086] is shown in Equation (2).

[0087]

Equation

[0088] l is the number of the OFDM symbol in the subframe.

[0089] (3) Frame and subframe:

[0090] Downlink transmission and uplink transmission are T f =(Δf max N f / 100) = 10 ms, each frame is formed with a duration of T sf = (Δf max N f / 1000) = 1 ms and contains 10 sub - frames. For example, one frame can include sub - frames #0 to #9. The number of consecutive OFDM symbols in each sub - frame is

[0091]

Number

[0092] as follows. Each frame is divided into two half - frames of the same size, namely, half - frame #0 and half - frame #1. Each half - frame contains 5 sub - frames. For example, half - frame #0 includes sub - frames #0 to #4, and half - frame #1 includes sub - frames #5 to #9.

[0093] (4) Slot:

[0094] Regarding the sub - carrier spacing configuration μ, the slots are sorted in ascending order in the sub - frame as

[0095]

Number

[0096] and in the frame as

[0097]

Number

[0098] in ascending order. In one slot

[0099]

Number

[0100] There are a number of consecutive OFDM symbols, where

[0101]

Number

[0102] the value of depends on the CP as shown in Tables 2 and 3. The start of the slot in the subframe

[0103]

Number

[0104] is aligned in time with the start of the OFDM symbol in the same subframe

[0105]

Number

[0106] and aligned in time. For example, if one slot contains 14 OFDM symbols, those OFDM symbols can be sorted based on time as OFDM symbol #0 to OFDM symbol #13.

[0107] The OFDM symbols in one slot can include three types: downlink symbols, uplink symbols, and flexible symbols. Uplink symbols are used only for uplink transmission. Downlink symbols are used only for downlink transmission. Flexible symbols do not have a determined transmission direction and can be used for uplink transmission or downlink transmission based on the indication of control signaling.

[0108]

Table 2

[0109]

Table 3

[0110] As described above, in a transmission solution based on OFDM technology, the key is that when a signal is received, the time-domain waveforms of a plurality of subcarriers can be completely separated and do not interfere with each other. However, when a low-power communication system such as passive IoT or ambient power-supported IoT is introduced into an NR system, there is no orthogonal relationship between the time-domain waveform of the synchronization signal (frame header 501) used in the low-power communication system and the time-domain waveform of the subcarriers used for data transmission in the NR system. When the synchronization signal used in the RFID system is directly used in the NR system, there is mutual interference between the synchronization signal and the subcarriers used for data transmission in the NR system. This affects the communication performance.

[0111] In consideration of this, embodiments of the present application provide a synchronization method. When a low-power communication system such as passive IoT or ambient power-supported IoT is introduced into an NR system, the synchronization signal of the low-power communication system such as passive IoT or ambient power-supported IoT can coexist with the subcarriers of the NR system.

[0112] Hereinafter, with reference to the accompanying drawings in the embodiments of the present application, the technical solutions in the embodiments of the present application will be described. In the description of the present application, unless otherwise specified, " / " indicates that the associated objects are in an "or" relationship. For example, A / B may represent A or B. In the present application, "and / or" only describes the association relationship between the associated objects and indicates that three relationships may exist. For example, A and / or B may indicate that only A exists, both A and B exist, and only B exists, where A and B may be singular or plural. In addition, in the description of the present application, unless otherwise specified, "a plurality of" means two or more. "At least one of the following items" or a similar expression indicates any combination of these items, including a single item or a plurality of items. For example, at least one of the items a, b, or c may indicate a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural. In addition, for the purpose of clearly describing the technical solutions in the embodiments of the present application, terms such as "first" and "second" are used in the embodiments of the present application to distinguish between the same items or similar items that basically provide the same function or purpose. Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity or execution sequence, and terms such as "first" and "second" do not indicate a clear difference.

[0113] In addition, the network architectures and service scenarios described in the embodiments of the present application are intended to more clearly describe the technical solutions in the embodiments of the present application, and do not constitute limitations on the technical solutions provided in the embodiments of the present application. Those skilled in the art will recognize that the technical solutions provided in the embodiments of the present application are applicable to similar technical problems as well, with the evolution of network architectures and the emergence of new service scenarios.

[0114] The technical solution in the embodiments of this application can be applied to the NR system. The technical solution in the embodiments of this application can also be applied to another communication system, such as a long term evolution (LTE) system, an LTE frequency division duplex (FDD) system, an LTE time division duplex (TDD) system, a universal mobile telecommunications system (UMTS), and a worldwide interoperability for microwave access (WiMAX) communication system, a communication system based on a wake-up mechanism, etc. The NR system in this application includes a non-standalone (NSA) NR system or a standalone (SA) NR system. The technical solution provided in this application can be further applied to a future communication system, such as a sixth-generation mobile communication system. Alternatively, the communication system can be a public land mobile network (PLMN), a device-to-device (D2D) communication system, a machine-to-machine (M2M) communication system, an IoT communication system, or another communication system.

[0115] FIG. 8 is a diagram of the architecture of a communication system according to an embodiment of this application. As shown in FIG. 8, this communication system includes a first device 801 and a second device 802. The first device 801 is a transmission end of a synchronization signal, and the second device 802 is a reception end of the synchronization signal. Referring to the UHF RFID system shown in FIG. 2, the first device 801 can be a reader 201, and the second device 802 can be a tag 202.

[0116] In connection with the wake-up mechanism-based system shown in FIG. 3, the first device 801 can be a network device 301, and the second device 802 can be a terminal device 302.

[0117] In connection with the NR system, the specific device form of the first device 801 can include an access network device in the NR system and a terminal device in the NR system. The specific device form of the second device 802 can include a terminal device in the NR system. The first device 801 and the second device 802 can perform data transmission by using OFDM technology. For example, the transmission of data sent from the first device 801 to the second device 802 can be performed via OFDM subcarriers. Alternatively, the transmission of data sent from the second device 802 to the first device 801 can be performed via OFDM subcarriers.

[0118] Hereinafter, an example in which the first device 801 interacts with the second device 802 is used for description.

[0119] In a possible implementation, the first device 801 generates a synchronization signal and sends the synchronization signal to the second device 802. The synchronization signal is generated in an OFDM format. The synchronization signal can include a first signal and / or a second signal. The first signal is used to determine the start position of the time domain occupied by the data sent from the first device 801 to the second device 802. The second signal is used to determine the frequency at which the second device 802 sends data to the first device 801. Correspondingly, the second device 802 receives the synchronization signal from the first device 801 and performs time synchronization and / or frequency synchronization based on the synchronization signal.

[0120] Specific implementations of the foregoing solutions are described in detail in the following embodiments. Details will not be described herein.

[0121] In this embodiment of the present application, the first device may generate a synchronization signal in an OFDM-like format, so that the synchronization signal and the OFDM subcarriers of the data (hereinafter abbreviated as downlink data) transmitted from the first device to the second device are orthogonal to each other. Further, when receiving a signal, the second device 802 can completely separate the time-domain waveform of the synchronization signal from the time-domain waveform of the OFDM subcarriers carrying the downlink data to avoid interference. Therefore, when a low-power communication system such as passive IoT or ambient power-supported IoT is introduced into the NR system, according to the synchronization method provided in the embodiment of the present application, the synchronization signal of the low-power communication system can coexist with the subcarriers of the NR system.

[0122] Regarding the NR system, hereinafter, the architecture of a communication system to which the synchronization method provided in the embodiment of the present application can be applied will be further described.

[0123] FIG. 9 shows another communication system 900 according to the present application. The communication system 900 may include access network devices #1 and #2 and terminal devices #1 to #8. The access network device #1 can directly transmit data from the terminal device #1 to the terminal device #6. Further, the access network device #1 may be the first device 801, and the terminal devices #1 to #6 may be the second device 802. The access network device #1 can transmit data to the terminal devices #7 and / or #8 by using the access network device #2. Further, the access network device #2 may be the first device 801, and the terminal device #7 or #8 may be the second device 802.

[0124] In communication system 900, access network device #2, terminal device #7, and terminal device #8 may form another communication system 910. In communication system 910, access network device #2 may directly transmit data to terminal device #7 or terminal device #8. Further, access network device #2 may be the first device 801, and terminal device #7 or terminal device #8 may be the second device 802.

[0125] In communication system 900, terminal device #4 and terminal device #6 may form another communication system 920. In communication system 920, terminal device #4 may directly transmit data to terminal device #5 and / or terminal device #6. Further, terminal device #4 may be the first device 801, and terminal device #5 or terminal device #6 may be the second device 802.

[0126] Note that in communication system 900, the first device 801 in the embodiments of the present application may be an access network device or a terminal device, and the second device 802 may be a terminal device. To facilitate understanding of the entity forms of the first device 801 and the second device 802 in the embodiments of the present application, hereinafter, an example in which the first device 801 is an access network device and the second device 802 is a terminal device will be used to describe the hardware structures of the first device 801 and the second device 802.

[0127] FIG. 10 is a diagram of the hardware structures of terminal device 1000 and access network device 1010 according to an embodiment of the present application.

[0128] The terminal device 1000 includes at least one processor 1001 (the example including one processor 1001 is used for explanation in FIG. 10), at least one memory 1002 (the example including one memory 1002 is used for explanation in FIG. 10), and at least one transceiver 1003 (the example including one transceiver 1003 is used for explanation in FIG. 10). Optionally, the terminal device 1000 may further include an output device 1004 and an input device 1005.

[0129] The processor 1001, the memory 1002, and the transceiver 1003 are connected via a communication line. The communication line may include a transmission path of information between the above components.

[0130] The processor 1001 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to control the program execution of the solution of the present application. In a specific implementation, in one embodiment, the processor 1001 may alternatively include a plurality of CPUs. The processor 1001 may be a single-CPU processor or a multi-CPU processor. The processor in this specification may be one or more devices, circuits, or processing cores configured to process data (for example, computer program instructions).

[0131] The memory 1002 can be a read-only memory (ROM), another type of static storage device capable of storing static information and instructions, a random access memory (RAM), or another type of dynamic storage device capable of storing information and instructions. It can also be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM), another compact disc storage, optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, or Blu-ray discs, etc.), magnetic disk storage media, another magnetic storage device, or any other medium capable of carrying or storing the intended program code in the form of instructions or data structures that can be accessed by a computer. However, the memory 1002 is not limited to these. The memory 1002 may exist independently or be connected to the processor 1001 via a communication line. Alternatively, the memory 1002 may be integrated with the processor 1001.

[0132] The memory 1002 is configured to store computer-executable instructions for executing the solution of the present application, and the processor 1001 controls the execution of the computer-executable instructions. Specifically, the processor 1001 is configured to execute the computer-executable instructions stored in the memory 1002 to implement the synchronization method of the embodiments of the present application. Optionally, the computer-executable instructions of the present embodiments of the present application may also be referred to as application program code or computer program code. This is not particularly limited in the present embodiments of the present application.

[0133] The transceiver 1003 can use any device such as a transceiver and is configured to communicate with another device or communication network such as, for example, Ethernet, a radio access network (RAN), or a wireless local area network (WLAN). The transceiver 1003 includes a transmitter Tx and a receiver Rx.

[0134] The output device 1004 communicates with the processor 1001 and can display information in a plurality of modes. For example, the output device 1004 can be a liquid crystal display (LCD), a light emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector.

[0135] The input device 1005 communicates with the processor 1001 and can receive user input in a plurality of modes. For example, the input device 1005 can be a mouse, a keyboard, a touch screen device, or a sensor device.

[0136] Network device 1010 includes at least one processor 1011 (illustrated using an example including one processor 1011 in FIG. 10), at least one memory 1012 (illustrated using an example including one memory 1012 in FIG. 10), at least one transceiver 1013 (illustrated using an example including one transceiver 1013 in FIG. 10), and at least one network interface 1014 (illustrated using an example including one network interface 1014 in FIG. 10). The processor 1011, the memory 1012, the transceiver 1013, and the network interface 1014 are connected via a communication line. The network interface 1014 is configured to be connected to a core network device via a link (e.g., S1 interface), or to be connected to a network interface of another network device via a wired or wireless link (e.g., X2 interface) (not illustrated in FIG. 10). This is not particularly limited in the embodiments of the present application. Further, for related descriptions of the processor 1011, the memory 1012, and the transceiver 1013, refer to the descriptions of the processor 1001, the memory 1002, and the transceiver 1003 of the terminal device 1000. Details will not be described again in this specification.

[0137] Optionally, the access network device 1010 of the present embodiment of the present application may be a device that accesses the core network, or a chip in a device that may be configured to access the core network. This is not particularly limited in the present embodiment of the present application. The device that accesses the core network may be, for example, a base station of a Long Term Evolution (LTE) system, a base station of a Global System for Mobile Communications (GSM), a base station of a UMTS, a base station of an NR system, a base station of a PLMN, a broadband network gateway (BNG), an aggregation switch, or a non-3GPP network device. The base station may include various forms of base stations such as, for example, a macro base station, a micro base station (also called a small cell), a relay station, and an access point. This is not particularly limited in the embodiments of the present application.

[0138] Optionally, the access network device 1010 of the present embodiment of the present application may also support backscatter communication technology.

[0139] Optionally, the access network device 1010 of the present embodiment of the present application may also support the transmission of wake-up signals.

[0140] Optionally, the access network device 1010 of the present embodiment of the present application may also be called an access device. This is not particularly limited in the present embodiment of the present application.

[0141] Optionally, the terminal device 1000 of the present embodiment of the present application may be a device configured to implement a wireless communication function, such as a terminal or a chip that may be used within a terminal. This is not particularly limited in the present embodiment of the present application. The terminal may be a user equipment (), access terminal, terminal unit, terminal station, mobile station, remote station, remote terminal, mobile device, wireless communication device, terminal agent, or terminal device in an LTE system, GSM, UMTS, NR system, or future evolved PLMN. The access terminal may be a mobile phone, cordless phone, session initiation protocol (SIP) phone, wireless local loop (WLL) station, personal digital assistant (PDA) station, handheld device with a wireless communication function, computing device, another processing device connected to a wireless modem, in-vehicle device, wearable device, virtual reality (VR) terminal device, augmented reality (AR) terminal device, wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, or wireless terminal in smart home, etc. The terminal device 1000 may be mobile or fixed.

[0142] Optionally, the terminal device 1000 of the present embodiment of the present application may support backscatter communication technology.

[0143] Optionally, the terminal device 1000 of the present embodiment of the present application may support the reception of wake-up signals.

[0144] Optionally, the terminal device 1000 of the present embodiment of the present application may also be referred to as a tag, an MTC terminal, an NR terminal, etc. This is not particularly limited in the present embodiment of the present application.

[0145] Hereinafter, with reference to FIGS. 8 to 10, the synchronization method according to the embodiment of the present application will be described in detail.

[0146] It should be noted that in the following embodiments of the present application, the names of signals or the names of parameters in the signals of devices are merely examples, and these signals or parameters may have other names during specific implementation. This is not particularly limited in the embodiments of the present application.

[0147] An example in which the first device 801 shown in FIG. 8 interacts with the second device 802 is used. As shown in FIG. 11, the synchronization method according to the embodiment of the present application includes the following steps.

[0148] S1101: The first device generates a synchronization signal. The synchronization signal is generated in an OFDM-like format. In other words, the time-domain waveform of the synchronization signal may be a waveform obtained by superimposing a plurality of orthogonal subcarriers. Furthermore, there is an orthogonal relationship between the time-domain waveform of the synchronization signal and the time-domain waveform of the subcarriers of the NR system.

[0149] Optionally, the synchronization signal may also be generated in a conventional OFDM (conventional OFDM) format. For example, the first device maps the sequence of the synchronization signal to subcarriers and then performs an inverse fast Fourier transform (IFFT) to generate the OFDM time-domain waveform of the synchronization signal.

[0150] It should be noted that the synchronization signal may alternatively be generated in a filtered-OFDM (F-OFDM) mode. Alternatively, in the embodiments of the present application, the synchronization signal may be generated in another OFDM mode. This is not particularly limited in the embodiments of the present application.

[0151] In the embodiments of the present application, the meaning of "sequence" may be the same as the meaning of "data". In this case, it should be noted that "data" may be represented as a "sequence" including a plurality of "0" or "1" symbols / elements. For example, the sequence [01010101101] may be represented as data transmitted by the first device or the second device. In other words, "sequence" and "data" can be mutually interchanged. This is uniformly described in this specification and will not be elaborated further below.

[0152] Optionally, in the embodiments of the present application, the time-domain waveform of the synchronization signal is generated in an OFDM mode. Alternatively, the time-domain waveform of the synchronization signal is an OFDM waveform.

[0153] Since a transmission solution based on OFDM technology is used in the downlink between the first device and the second device, it can be understood that the minimum transmission unit of the synchronization signal or data transmitted by the first device to the second device is one OFDM symbol. In other words, the time-domain resource of the synchronization signal may include one OFDM symbol or a plurality of OFDM symbols. The time-domain resource of the synchronization signal may include the time length of the synchronization signal and the time-domain position of the synchronization signal. The time-domain position of the synchronization signal includes the time-domain start position and / or the time-domain end position of the synchronization signal.

[0154] For example, FIG. 12 is a diagram in which the time domain resource of the synchronization signal includes one OFDM symbol. The time domain resource of the synchronization signal includes OFDM symbol #1 in one subframe. The start position of the time domain of the synchronization signal is the start position of the time domain of OFDM symbol #1 in this subframe, the end position of the time domain of the synchronization signal is the end position of the time domain of OFDM symbol #1 in this subframe, and the time length of the synchronization signal is the time length of OFDM symbol #1 (i.e., one OFDM symbol).

[0155] For example, FIG. 13 is a diagram in which the time domain resource of the synchronization signal includes two OFDM symbols in one subframe. The time domain resource of the synchronization signal includes OFDM symbol #1 and OFDM symbol #2. The start position of the time domain of the synchronization signal is the start position of the time domain of OFDM symbol #1 in the subframe, the end position of the time domain of the synchronization signal is the end position of the time domain of OFDM symbol #2 in the subframe, and the time length of the synchronization signal is the sum of the time lengths of OFDM symbol #1 and OFDM symbol #2 (i.e., two OFDM symbols).

[0156] As described in the related technical description part in a specific implementation, in the present embodiment of the present application, since the synchronization signal is located before the downlink data transmitted by the first device, the second device determines the start position of the time domain of the downlink data. For example, FIG. 14 is a diagram of the time domain resource of the synchronization signal according to the embodiment of the present application. This synchronization signal may be adjacent to the downlink data. In other words, after receiving the synchronization signal, the second device may use the synchronization signal to determine the start position of the time domain of the downlink data.

[0157] Optionally, in the present embodiment of the present application, a guard interval (GI) may be added before or after the OFDM time domain signal of the synchronization signal. The GI may be a CP.

[0158] Note that FIG. 15 is a diagram of the structure of an OFDM symbol according to an embodiment of the present application. When the GI is added before or after the OFDM time-domain signal, one OFDM symbol includes two parts, namely, the GI and the desired signal (payload). The desired signal is an OFDM symbol obtained by IFFT on the OFDM frequency-domain signal. In other words, the desired signal in the OFDM symbol is the part used for the transmission of "sequence", "data", or "information".

[0159] It can be understood that the time length of the OFDM symbol is the sum of the time length T GI of the GI and the time length T payload of the desired signal.

[0160] It should be understood that the "desired signal" can be replaced with "data", "sequence", "desired data", "load", "desired load", "payload", and "effective payload", etc. This is uniformly described in this specification. Details will not be repeatedly described below.

[0161] Furthermore, "transmission" has the same meaning as "carrier". In other words, "transmission" and "carrier" can be mutually interchanged. This is uniformly described in this specification. Details will not be repeatedly described below.

[0162] It can be understood that the time length T payload of the desired signal is related to the sampling frequency and the number of sampling points of the IFFT. In other words, the time length T payload of the desired signal can be represented by the sampling frequency and the number of sampling points. Correspondingly, the time length T GI of the GI can also be represented by the sampling frequency and the number of sampling points.

[0163] Optionally, in the present embodiment of the present application, the synchronization signal may include a first signal (which may also be referred to as a delimiter). The first signal is used to determine the start position of the time domain occupied by the data (downlink data) transmitted from the first device to the second device. In other words, the start position of the time domain of the downlink data may be determined using the first signal in the synchronization signal.

[0164] Optionally, in a communication system based on a wake-up mechanism, the synchronization signal may include a first signal (which may also be referred to as a delimiter). The first signal is used to determine the start position of the time domain occupied by the data (downlink data) transmitted from the first device to the second device. In other words, the second device may determine the start position of the time domain of the downlink data using the first signal in the synchronization signal. The downlink data may include a preamble and a wake-up signal. The preamble may be a sequence including "0" and "1". The wake-up signal may indicate an identifier of the second device. Alternatively, the wake-up signal may indicate an identifier of a terminal device group to which the second device belongs. Alternatively, the wake-up signal may indicate a part of the identifier of the second device. Alternatively, the wake-up signal may indicate an identifier of a terminal device group to which the second device belongs.

[0165] Optionally, in the present embodiment of the present application, the first signal may be used to wake up the second device. In other words, after the second device receives the first signal from the first device, the counter of the second device starts to operate, starts to detect the time length of the received signal, and receives and demodulates the downlink data. In other words, before the second device receives the first signal, in order to obtain an energy-saving effect, the counter of the second device may not operate and may not detect the time length of the received signal.

[0166] For example, FIG. 16 is a diagram of another time domain resource of a synchronization signal according to an embodiment of the present application. The first device transmits a carrier signal before the synchronization signal. The carrier signal is used to provide energy to the second device, that is, the carrier signal is a high-level signal. Correspondingly, the first signal may be a low-level signal. In other words, when the second device receives the low-level first signal after the carrier signal, the second device may determine to start receiving downlink data.

[0167] Optionally, in the present embodiment of the present application, the synchronization signal may include a second signal (which may also be called a calibration signal). The second signal is used to determine the frequency at which the second device transmits data to the first device. For example, the frequency at which the second device transmits data to the first device may be the BLF. Further, the second device may determine the BLF using Equation (1).

[0168] In the present embodiment of the present application, the functions that can be implemented by the first signal may include the functions implemented by the delimiter in the frame header of the preamble part, and the functions that can be implemented by the second signal may include the functions implemented by the TR in the frame header of the preamble part. cal may include the functions implemented by.

[0169] In a possible implementation, the synchronization signal includes only the first signal. As described above, the time domain resource of the synchronization signal includes one or more OFDM symbols. Therefore, when the synchronization signal includes only the first signal, the time length of the first signal may be the time length of the one or more OFDM symbols.

[0170] For example, in a scenario where the synchronization signal includes only the first signal, it may be the case that the first device transmits downlink signaling other than the query command to the second device. In this case, since the downlink signaling other than the query command does not include DR, the second device does not need to calculate the BLF. Further, the synchronization signal may include only the first signal. Alternatively, when the second device has already determined the BLF, the synchronization signal may include only the first signal.

[0171] Alternatively, in another possible implementation, the synchronization signal includes the first signal and embedded data. In other words, when the time length of the first signal is less than the time length of one OFDM symbol, or when the time length of the first signal is less than the time length of the synchronization signal, the time length of the synchronization signal may be the time length of one or more OFDM symbols due to the embedded data. The embedded data may be invalid data or unnecessary data.

[0172] Alternatively, in another possible implementation, the synchronization signal includes the first signal and the second signal. In other words, the second device may determine the time domain start position of the downlink data and the BLF based on the synchronization signal.

[0173] For example, in a scenario where the synchronization signal includes the first signal and the second signal, it may be the case that the downlink signaling transmitted by the first device is a query command, and the query command carries DR. In this case, the second device may determine the time domain start position of the downlink data based on the first signal, and then may obtain the second signal and the DR in the query command. Further, the second device may also obtain the BLF by calculation based on the time length of the second signal, the DR, and Equation (1).

[0174] S1102: The first device transmits the synchronization signal to the second device. Correspondingly, the second device receives the synchronization signal from the first device.

[0175] S1103: The second device performs time synchronization and / or frequency synchronization based on the synchronization signal.

[0176] In other words, the second device may determine the start position of the time domain occupied by the downlink data based on the first signal in the synchronization signal, and determine the BLF based on the second signal in the synchronization signal.

[0177] In the present embodiment of the present application, since the synchronization signal is generated in the OFDM format, the synchronization signal and the OFDM subcarriers used for the transmission of the downlink data are orthogonal to each other. Therefore, when demodulating the signal, the second device may completely separate the time domain waveform of the synchronization signal from the time domain waveform of the OFDM subcarriers used for the transmission of the downlink data to avoid interference. Therefore, when a low-power communication system such as a passive IoT or an ambient power-supported IoT is introduced into the NR system, the synchronization signal of the low-power communication system can coexist with the subcarriers of the NR system.

[0178] In the present embodiment of the present application, when the first device is an access network device, the actions of the first device in steps S1101 to S1103 above may be instructed to be executed by the access network device by calling the application program code stored in the memory 1012 by the processor 1011 in the access network device 1010 shown in FIG. 10, or when the first device is a terminal device, the actions of the first device in steps S1101 to S1103 above may be instructed to be executed by the terminal device by calling the application program code stored in the memory 1002 by the processor 1001 in the terminal device 1000 shown in FIG. 10. This is not limited in the present embodiment.

[0179] In the present embodiment of the present application, when the second device is a terminal device, the actions of the second device in steps S1101 to S1103 above may be commanded to be executed by the terminal device by calling the application program code stored in the memory 1002 by the processor 1001 in the terminal device 1000 shown in FIG. 10. This is not limited in the present embodiment.

[0180] Optionally, in the present embodiment of the present application, the second signal is located after the first signal. In other words, after the second device detects the first signal, the second device may detect the second signal, obtain the time length of the second signal, and further calculate the BLF with reference to the DR carried in the downlink data.

[0181] Optionally, in a possible implementation, the first signal and the second signal are located in different OFDM symbols.

[0182] Optionally, the time interval between the OFDM symbol occupied by the first signal and the OFDM symbol occupied by the second signal is predefined. In other words, after detecting the first signal, the second device may determine the OFDM symbol occupied by the second signal.

[0183] The time interval between the OFDM symbol occupied by the first signal and the OFDM symbol occupied by the second signal may be pre-determined by the first device and the second device, or the time interval between the OFDM symbol occupied by the first signal and the OFDM symbol occupied by the second signal may be preset on the second device, or the time interval between the OFDM symbol occupied by the first signal and the OFDM symbol occupied by the second signal may be agreed upon in the protocol. This is not particularly limited in the present embodiment of the present application.

[0184] For example, the time interval between the OFDM symbol occupied by the first signal and the OFDM symbol occupied by the second signal is 0. As shown in FIG. 17, the first signal and the second signal are located in two adjacent OFDM symbols. In other words, after detecting the first signal, the second device may determine that the OFDM symbol after the first signal carries the second signal.

[0185] For example, the time interval between the OFDM symbol occupied by the first signal and the OFDM symbol occupied by the second signal is T OFDM symbols, where T is a positive integer, and the OFDM symbol occupied by the first signal and the OFDM symbol occupied by the second signal are separated by T OFDM symbols. In other words, after detecting the first signal, the second device may start receiving the second signal after T OFDM symbols.

[0186] Optionally, in another possible implementation, the first signal and the second signal are located in the same OFDM symbol. In other words, after detecting the first signal, the second device may determine to start receiving the second signal.

[0187] For example, FIG. 18 shows an example of a diagram of the structure of a synchronization signal in which the first signal and the second signal are located in the same OFDM symbol. The second signal may be adjacent to the first signal. The sum of the time length of the second signal and the time length of the first signal may be the time length of one OFDM symbol, or the sum of the time length of the second signal and the time length of the first signal may be less than the time length of one OFDM symbol. This is not particularly limited in the present embodiment of this application.

[0188] It should be noted that the synchronization signal may further include other symbols, such as the data 0 and RT in the preamble part. cal

[0189] ​Optionally, in the embodiments of the present application, the time interval between the first signal and the second signal is predefined. In other words, after detecting the first signal, the second device may determine the start position of the time domain of the second signal.

[0190] The time interval between the first signal and the second signal may be predetermined by the first device and the second device, or the time interval between the first signal and the second signal may be preset on the second device, or the time interval between the first signal and the second signal may be agreed upon by the protocol. This is not particularly limited in the embodiments of the present application.

[0191] Hereinafter, the steps S1101 of two modes for generating the time domain waveform of the synchronization signal will be described in detail.

[0192] Mode 1: The waveform of the synchronization signal may be a cyclic prefix orthogonal frequency division multiplexing (conventional OFDM using a cyclic prefix, CP-OFDM) waveform. In other words, the OFDM symbol occupied by the synchronization signal includes two parts, namely, the CP and the desired signal. Further, the time length of one OFDM symbol is the sum of the time length T CP of the CP and the time length T payload of the desired signal.

[0193] As described in the preamble part, the time length T CP of the CP satisfies

[0194]

Number

[0195] , where

[0196]

Number

[0197] may be obtained using Equation (2). Correspondingly, the time length T of the desired signal payload can also be represented by a constant κ, a subcarrier interval setting μ, and a time unit T, as shown in Equation (3). c Z = 2048κ·2 -μ ·T c Equation (3)

[0198] Z may represent the time length T of the desired signal payload

[0199] For example, referring to the communication system 900 shown in FIG. 9, a scenario where the waveform of the synchronization signal transmitted by the first device is a CP-OFDM waveform will be described. In the communication system 900, the access network device #1 may directly transmit data from the terminal device #1 to the terminal device #6. Therefore, the access network device #1 may be the first device, and the terminal devices #1 to #6 may be the second devices. In this case, the synchronization signal transmitted by the first device is a signal transmitted via the downlink of the NR system, and the waveform transmitted via the downlink of the NR system is a CP-OFDM waveform. Further, the waveform of the synchronization signal may be a cyclic prefix orthogonal frequency division multiplexing waveform (the downlink transmission waveform is a conventional OFDM using a cyclic prefix).

[0200] Optionally, in a possible implementation, the waveform of the synchronization signal is generated in a CP-OFDM manner based on the first sequence. The first sequence is a pre-defined sequence.

[0201] Optionally, the first sequence may include a plurality of elements.

[0202] Each element may be represented by a binary symbol "0" or "1".

[0203] ​​Alternatively, each element may be a complex number and may be represented as a + bj, where j 2 = -1 and a and b are real numbers.

[0204] For example, the first sequence may include k placement points. The placement points can be ASK placement points, phase - shift keying (PSK) placement points, and quadrature amplitude modulation (QAM) placement points. The modulation orders of ASK, PSK, and QAM are not particularly limited in the present embodiment of this application.

[0205] Note that the first sequence may be stored or set in the first device in advance, or the first sequence may be agreed upon by a protocol. This is not particularly limited in the present embodiment of this application.

[0206] For example, FIG. 19 is a diagram of a module framework of a waveform generation mode of a synchronization signal according to an embodiment of this application. In this synchronization signal, sub - carrier mapping is performed on the first sequence, and the first sequence may be mapped to sub - carriers. Then, IFFT is performed and a CP is added to generate the waveform of the synchronization signal. The CP may be added before the desired signal.

[0207] Mode 2: The waveform of the synchronization signal is a CP - OFDM waveform and is generated in a (discrete Fourier transform, DFT) transform precoding mode. In other words, compared with Mode 1, in Mode 2, a DFT operation is added to perform a conversion from the time domain to the frequency domain. Furthermore, since the synchronization signal transmitted by the first device is a time - domain signal, it is possible to avoid the problem of high peak to average power ratio (PAPR) caused by transmitting a frequency - domain OFDM signal.

[0208] Optionally, in the embodiments of the present application, the waveform of the synchronization signal is a CP-OFDM waveform and is generated in a conversion precoding manner of DFT spreading. Alternatively, the waveform of the synchronization signal is a CP-OFDM waveform and the waveform of the synchronization signal has a conversion precoding function for performing DFT expansion.

[0209] It should be noted that "spreading" has the same meaning as "expansion". In other words, "spreading" and "expansion" can be mutually interchanged. This is uniformly described in this specification and will not be elaborated further below.

[0210] Furthermore, the OFDM mode corresponding to mode 2 may also be called discrete fourier transform-spread OFDM (DFT-S-OFDM).

[0211] For example, with reference to the communication system 920 shown in FIG. 9, a scenario where the waveform of the synchronization signal is a DFT-S-OFDM waveform will be described. In the communication system 920, the terminal device #4 may directly transmit data to the terminal device #5 and / or the terminal device #6. Therefore, the terminal device #4 may be the first device, and the terminal device #5 or the terminal device #6 may be the second device. The communication link used by the terminal device to transmit data may be the uplink of the NR system. Therefore, the waveform of the synchronization signal transmitted by the first device may be the waveform of the uplink transmission of the NR system, and the waveform of the uplink transmission of the NR system is a DFT-S-OFDM waveform. Furthermore, a DFT-S-OFDM waveform (the downlink transmission waveform is a conventional OFDM using a CP having a conversion precoding function for performing DFT spreading) is used as the waveform of the synchronization signal.

[0212] Optionally, in the embodiments of the present application, the generation of the waveform of the synchronization signal in the DFT conversion pre-coding format includes that the waveform of the synchronization signal is a waveform obtained by CP-OFDM for the second sequence. The second sequence is a sequence obtained by DFT spread conversion pre-coding for the first sequence.

[0213] For example, FIG. 20 is a diagram of a module framework of another waveform generation mode of the synchronization signal according to an embodiment of the present application. In this synchronization signal, DFT may be executed on the first sequence to obtain a second sequence, sub-carrier mapping is executed on the second sequence, then IFFT is executed, and a CP is added to generate the waveform of the synchronization signal.

[0214] The time domain position and time length of the first signal will be further described below.

[0215] Optionally, in the embodiments of the present application, the time domain resource of the first signal includes the first K time units among the N time units corresponding to the desired signal in one OFDM symbol, where K is a positive integer. In other words, since the time domain resource of the first signal includes the start part of the desired signal in the OFDM symbol, the second device may first detect the first signal before the second signal and downlink data, and then receive the downlink data or the second signal. Further, when K is less than N, the first signal occupies only a part of the time domain resource of the OFDM symbol. Therefore, the idle time domain resources of the OFDM symbol can be used for the transmission of other contents such as the second signal, Data 0, or RT cal and the like, so that the utilization of the time domain resources of the OFDM symbol can be improved.

[0216] For example, FIG. 21 is a diagram of the time-domain resource of the first signal according to an embodiment of the present application. The time length of the desired signal is N time units, and the time-domain resource of the first signal includes the first K time units among the N time units. In other words, the time-domain end position of the first signal is the Kth time unit among the N time units, and the time length of the first signal is K time units or more. K may be equal to N.

[0217] Optionally, in the present embodiment of the present application, the time-domain resource of the first signal may include time-domain units corresponding to a positive integer number of OFDM symbols. This positive integer number of OFDM symbols is used to carry the first signal. The time-domain unit corresponding to this OFDM symbol may be the time length of one OFDM symbol.

[0218] Optionally, in the present embodiment of the present application, the time unit is a constant κ, the unit of time T C 、the unit of time T S 、the default sampling points of the IFFT, the default sampling frequency of the IFFT, or the subcarrier spacing, etc.

[0219] Note that the meaning of the "default sampling points of the IFFT" is the same as the meaning of the "sampling points of the IFFT". In other words, the "default sampling points of the IFFT" and the "sampling points of the IFFT" can be mutually interchanged for the purpose of explanation. This is uniformly described in this specification. Details will not be repeatedly described below.

[0220] Hereinafter, with reference to the time-domain waveform of the signal, the time length of the first signal will be further described.

[0221] Optionally, in the present embodiment of the present application, before receiving the first signal from the first device, the second device may detect the duration of the received signal. In other words, the second device may detect the duration of the received signal and determine whether the received signal is the first signal by comparing the duration of the received signal with the duration of the first signal.

[0222] Optionally, in the present embodiment of the present application, the first signal is a low-level signal. In other words, when detecting a low-level signal having a duration longer than the duration of the first signal, the second device may determine that the first signal has been detected.

[0223] Optionally, in the present embodiment of the present application, the amplitude of the time-domain waveform corresponding to the first signal is less than a third threshold. Alternatively, the absolute value of the amplitude of the time-domain waveform corresponding to the first signal is less than a fourth threshold. Alternatively, the maximum value of the amplitude of the time-domain waveform corresponding to the first signal is less than a fifth threshold.

[0224] Optionally, the average value of the amplitude of the time-domain waveform corresponding to the first signal is less than a sixth threshold.

[0225] Correspondingly, after receiving the signal, the second device may calculate the average value of the amplitude of the time-domain waveform of the received signal. In other words, if the average value is less than the sixth threshold, the second device determines that the received signal is the first signal.

[0226] It should be noted that the third threshold to the sixth threshold may be predefined. The third threshold to the sixth threshold may be equal or not equal. Taking the third threshold and the fifth threshold as examples, the third threshold may be less than the fifth threshold, the third threshold may be equal to the fifth threshold, or the third threshold may be greater than the fifth threshold.

[0227] Furthermore, the values from the third threshold to the sixth threshold are not particularly limited in the present embodiment of the present application.

[0228] For example, a scenario where the first signal is at a low level may be a scenario occupied in FIG. 16 where, for example, the first device provides energy to the second device by using a carrier signal. Since the carrier signal supplies energy to the second device, it can be understood that the carrier signal is a high-level signal. In this way, when the second device receives the low-level first signal, the second device may determine to start receiving downlink data.

[0229] Optionally, in a possible implementation, the time-domain resource of the first signal further includes a part of the time units corresponding to the CP in the OFDM symbol where the first signal is located. The level of the signal of the CP is the same as the level of the first signal. In other words, when the first signal is at a low level, a part of the time units corresponding to the CP is added to the time-domain resource of the first signal, so that the duration of the low-level signal is long enough. Furthermore, the first signal may be distinguished from the low-level part of the second signal and / or the low-level part of the downlink data. In this way, when receiving a signal, the second device may determine that the low-level signal having the longest time duration in the received signal is the first signal.

[0230] For example, using the diagram of the downlink signal structure shown in FIG. 22, the determination by the second device that the first signal is detected will be described. The time duration of the first signal is greater than the time duration of the low-level part of the downlink data and greater than the time duration of the low-level part of the second signal. Furthermore, when receiving the downlink signal, the second device may determine that the low-level signal having the minimum time duration is the first signal.

[0231] Correspondingly, corresponding to the case where the synchronization signal is generated in the DFT mode of pattern 2, the quantity of consecutive 0 symbols (low level) in the third sequence used to generate the second signal in the first sequence is less than the quantity of consecutive 0 symbols (low level) in the fourth sequence used to generate the first signal in the first sequence.

[0232] For example, the first sequence is [000111100110]. The first three elements in the first sequence are the fourth sequence

[0000] , and the third sequence may be the portion [111100110] obtained by removing

[0000] from the first sequence. Further, the quantity of consecutive 0 symbols (2) in the third sequence is less than the quantity of consecutive 0 symbols (3) in the fourth sequence. Optionally, the CP of one OFDM symbol may be obtained by copying the signal carried in the last S1 time units among the N time units corresponding to the desired signal in that OFDM symbol. The time length of the last S1 time units is equal to the time length of the CP of the OFDM symbol.

[0233] Optionally, in the present embodiment of the present application, the signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is located is a low-level signal. The time length of the last S time units is not less than the time length of the CP of the OFDM symbol where the first signal is located. In other words, since the signal carried in the last S time units corresponding to the desired signal in the OFDM symbol where the first signal is located is a low-level signal, it is possible to ensure that the level of the CP signal is low. In this way, the duration of the low-level portion of the first signal may be increased.

[0234] Optionally, in the present embodiment of the present application, the last element of the first sequence is 0. In other words, the first sequence ends with 0. For example, the first sequence is [000111100110], and the last element of this sequence is 0.

[0235] Optionally, the amplitude of the time-domain waveform of the signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is located is less than a third threshold.

[0236] Optionally, the absolute value of the amplitude of the time-domain waveform of the signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is located is less than a fourth threshold.

[0237] Optionally, the maximum value of the amplitude of the time-domain waveform of the signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is located is less than a fifth threshold.

[0238] Optionally, the average value of the amplitude of the time-domain waveform of the signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is located is less than a sixth threshold.

[0239] Optionally, in a possible implementation, the third threshold to the sixth threshold may be less than or equal to the average value of the amplitude of the desired signal in the OFDM symbol where the first signal is located.

[0240] Optionally, in an embodiment where the waveform of the synchronization signal is generated based on the first sequence in a CP-OFDM format, the first sequence includes Q elements, and the last P elements among the Q elements are first symbols indicating a low level.

[0241] For example, when each element of the first sequence is represented using symbol 0 or 1, the first sequence may be symbol 0.

[0242] Hereinafter, from the viewpoint that the second device detects the first signal, the time length of the first signal will be further described.

[0243] Optionally, in the present embodiment of the present application, the time length of the first signal is predefined. In other words, for the second device, the time length of the first signal is known. When the second device detects a low-level signal within a known time length, the second device may determine that the first signal has been detected. In this way, it is possible to improve the efficiency of detecting the first signal by the second device and / or reduce the complexity of detecting the first signal by the second device.

[0244] It should be noted that the time length of the first signal may be stored or set in the second device in advance, or the time length of the first signal may be agreed upon by a protocol. This is not particularly limited in the present embodiment of the present application.

[0245] Optionally, the time length of the first signal may change depending on the time domain resource where the first signal is located. In other words, the time length of the first signal may change depending on the time domain resource for transmitting the first signal.

[0246] For ease of understanding, the change state of the time length of the first signal depending on the time domain resource will be described from two viewpoints, namely the subcarrier spacing and the CP type viewpoints.

[0247] As shown in Equation (3), the time length T of the desired signal payload has a value of Z, and this T payloadThe value of is further equal to the above N time units, where Z is represented by the constant κ and the subcarrier interval setting μ. In other words, when the subcarrier interval settings are different, the value of Z is also different. Therefore, the value of the time unit changes depending on different subcarrier interval settings. Furthermore, the time lengths of the K time units also change depending on different subcarrier interval settings. In other words, when the subcarrier interval settings are different, the time length of the first signal (including K time units) is also different. The larger the value of the subcarrier interval setting, the smaller the value of the time unit, and furthermore, the shorter the time length of the K time units in the first signal.

[0248] It should be noted that when the time domain resource of the first signal includes the CP of the OFDM symbol where the first signal is located, even when the subcarrier interval settings are the same, the time length of the first signal may be different. One example is as follows. That is, as described in the preamble part, when the subcarrier interval settings are the same, the CP types may be different. For example, when the subcarrier interval setting μ is 2, the subcarrier interval Δf is 60 kHz, and the CP is either normal CP or extended CP. Through signaling settings, it may be determined that normal CP or extended CP is used when μ is 2. The time length corresponding to normal CP is different from the time length corresponding to extended CP.

[0249] Furthermore, the time lengths of the CPs corresponding to different OFDM symbols may be different. FIG. 23 is a diagram of the time lengths of each OFDM symbol in one slot in the NR system according to an embodiment of the present application. As described in Equation (2), in normal CP, the time lengths of the CPs of OFDM symbol #0 and OFDM symbol #7 are larger than the time lengths of the CPs of OFDM symbols with other numbers.

[0250] In other words, when the time-domain resource of the first signal includes the CP of the OFDM symbol where the first signal is located, even when the same subcarrier setting is used, the time length of the first signal varies depending on the CP type. In other words, the time length of the first signal varies depending on the position of the OFDM symbol.

[0251] For ease of explanation, in the present embodiment of the present application, for the normal CP, the CP of OFDM symbol #0 and the CP of OFDM symbol #7 are represented as "long CP", and the CPs of OFDM symbols with other numbers are represented as "short CP".

[0252] Optionally, in the present embodiment of the present application, the time length of the CP of the OFDM symbol where the first signal is located is fixed. In other words, when the same subcarrier interval setting is used, the second device does not need to blindly detect the first signal with different time lengths when receiving the first signal. Thereby, the efficiency of detecting the first signal by the second device can be improved and / or the complexity of detecting the first signal by the second device can be reduced.

[0253] Optionally, in a possible implementation, the OFDM symbol where the first signal is located is an OFDM symbol including a short CP among the normal CPs. In other words, the time length of the CP of the OFDM symbol where the first signal is located is 144κ·2 -μ ·T C in Equation (2). Furthermore, when the same subcarrier interval setting is used, the time length of the first signal is a fixed value.

[0254] Optionally, the number of OFDM symbols where the first signal is located satisfies l≠0 or l≠7·2 μ In other words, the time length of the CP of the OFDM symbol where the first signal is located is 144κ·2 -μ ·T C in Equation (2).

[0255] Optionally, in another possible implementation, the OFDM symbol in which the first signal is located is an OFDM symbol including the long CP among the normal CPs. In other words, the time length of the CP of the OFDM symbol in which the first signal is located is (144κ·2 -μ +16κ)·T C in Equation (2). Furthermore, when the same subcarrier interval setting is used, the time length of the first signal is a fixed value.

[0256] Optionally, the number of OFDM symbols in which the first signal is located satisfies l = 0 or l = 7·2 μ In other words, the time length of the CP of the OFDM symbol in which the first signal is located is (144κ·2 -μ +16κ)·T C in Equation (2).

[0257] Optionally, in another possible implementation, the OFDM symbol in which the first signal is located is an OFDM symbol including an extended CP. In other words, the time length of the CP of the OFDM symbol in which the first signal is located is 512κ·2 -μ ·T C in Equation (2). Furthermore, when the same subcarrier interval setting is used, the time length of the first signal is a fixed value.

[0258] Optionally, in the present embodiment of the present application, the subcarrier interval of the first signal is 60 kHz. Alternatively, the subcarrier interval setting μ of the first signal is 2. In other words, the time length of the CP of the OFDM symbol in which the first signal is located is 512κ·2 -μ ·T C in Equation (2).

[0259] Next, from the perspective of the utilization of time-domain resources for transmitting the first signal by the first device, the time length of the first signal will be further described.

[0260] Optionally, in the present embodiment of the present application, the time length of the first signal is greater than or equal to a first threshold and less than or equal to a second threshold. The first threshold is T LCPGreater than or equal to +t·Z, and T LCP is the duration of the long CP, Z is the duration of the desired signal T payload and t is a coefficient. The second threshold is T SCP Less than or equal to +t·Z, and T SCP is the duration of the short CP. In other words, the duration of the first signal may vary within a small range. Furthermore, the first device can transmit the first signal at any time domain position. In other words, since the first device does not need to transmit the first signal on a specific time domain resource, it is possible to improve the utilization of the time domain resource.

[0261] Note that the value of t can be 1, 1 / 2, 1 / 4, or 1 / 5, etc. This is not particularly limited in the present embodiment of this application.

[0262] For ease of understanding, the first threshold and the second threshold are described with reference to the NR system parameters of the preamble part.

[0263] FIG. 24 is a diagram of the value ranges of the first threshold and the second threshold according to an embodiment of this application. The first threshold is X + Y, and the second position period is X - Y. X = t·Z+(T LCP +T SCP ) / 2, and Y ≧ (T LCP -T SCP ) / 2. In the present embodiment of this application, Z = 2048κ·2 -μ ·T C and T LCP =(144κ·2 -μ +16κ)·T C and T SCP =144κ·2 -μ ·T C When these parameters are substituted into X and Y, X=(2048κ·2 -μ +144κ·2 -μ +8κ)·T C =(2192κ·2 -μ +8κ)·T C , and Y ≧ 8κ·T Cmay be obtained.

[0264] Optionally, in the present embodiment of the present application, when the second device detects a low-level signal within the time range [X - Y, X + Y], the second device determines that the first signal has been detected.

[0265] Hereinafter, with reference to the OFDM format for generating a synchronization signal, the time-domain resource of the second signal in the present embodiment of the present application will be further described.

[0266] Optionally, in the present embodiment of the present application, the time-domain resource of the second signal includes M of the N time units corresponding to the desired signal in the OFDM symbol, where M is a positive integer. In the process of generating an OFDM symbol, IFFT is required, and an integer is obtained through IFFT sampling. If M in the M time units included in the time-domain resource of the second signal is not a positive integer, after IFFT is executed, the non-integer part is quantized to an integer. In this case, an error is introduced. In other words, in the process of generating the second signal via OFDM, since M is a positive integer, it is possible to reduce the error introduced through quantization at the default sampling rate of IFFT.

[0267] For example, FIG. 25 is a diagram of the time-domain resource of the second signal according to an embodiment of the present application. The time length of the desired signal is N time units, and the time-domain resource of the second signal includes M of the N time units.

[0268] It should be noted that these M time units are M consecutive time units.

[0269] Optionally, in the present embodiment of the present application, the time unit may be a constant κ, the unit of time T c , the unit of time T S , the default sampling point of IFFT, the default sampling frequency of IFFT, or the subcarrier interval, etc.

[0270] Optionally, in the present embodiment of the present application, the synchronization signal includes a second signal. The waveform of the synchronization signal is generated in a CP-OFDM mode by performing DFT transform precoding on a first sequence. The first sequence includes a third sequence. The third sequence is a sequence used to generate the second signal.

[0271] M satisfies a first condition, and the first condition includes the following.

[0272] N is L times M, and the number of elements included in the first sequence is L times the number of elements included in the third sequence, where N is a power of 2 and L is a positive integer.

[0273] Hereinafter, with reference to the diagram of the time domain resources of the downlink signal shown in FIG. 26, the time domain resources of the second signal will be described.

[0274] For example, FIG. 26 is a diagram of the time domain resources of a downlink signal according to an embodiment of the present application. The downlink signal includes a carrier signal, a synchronization signal, and downlink data. The carrier signal is transmitted in OFDM symbol #0 before the synchronization signal, and the carrier signal is used to provide energy to a second device, and the carrier signal is at a high level. The OFDM symbol #1 after the carrier signal carries the synchronization signal, and the OFDM symbol #2 after the synchronization signal carries the downlink data.

[0275] The synchronization signal includes a first signal and a second signal. The subcarrier interval of the synchronization signal is 15 kHz, and the time length of the first signal is 21.6 μs ± 2%, that is, the tolerance range is 2%. In other words, considering the CP lengths of different OFDM symbols, the synchronization signal can be transmitted in any OFDM symbol. Furthermore, the time domain resource setting of the synchronization signal is flexible and has a high utilization rate.

[0276] When the sampling rate is 1.92 MHz, the number of sampling points of one OFDM symbol is 128, that is, the desired signal in one OFDM symbol corresponds to 128 time units. Correspondingly, corresponding to the case where the synchronization signal is generated in the DFT pattern of mode 2, the first sequence may be [000111100110], and the number of elements in the first sequence is 12. The second signal corresponds to [111100] in the first sequence, that is, the third sequence, and the number of elements in the third sequence is 6. Furthermore, the number of elements in the first sequence is twice the number of elements in the third sequence, that is, L = 2. Based on the first condition, M = 128 / 2 = 64. Thus, the number M of sampling points of the second signal in the time domain is an integer, and the length of the second signal is 33.3 μs.

[0277] In the present embodiment of the present application, the "time unit" and the "number of sampling points" obtained via OFDM can be mutually interchanged for the purpose of explanation. This is uniformly described in this specification. Details will not be repeatedly described below.

[0278] Hereinafter, with reference to the mode in which the second device measures the time length of the signal, the time length of the second signal will be further described.

[0279] Optionally, in a possible implementation, the second device measures the time length of the second signal using a counter.

[0280] It should be noted that since the signal boundary is not exactly aligned with the clock boundary, the counting error range of the counter is ± clock cycle.

[0281] For example, FIG. 27 is a diagram in which a second device measures the time duration of a high-level portion using a counter. The time duration of signal 1 is 3 clock cycles, and the boundary of signal 1 is aligned with the clock boundary. Therefore, signal 1 can be accurately counted as exactly 3 clock cycles. The time duration of signal 2 is 2.5 clock cycles, and the boundary of signal 2 is not aligned with the clock cycle, and the counter can only perform integer counting. Therefore, signal 2 is counted as 3 clock cycles. In this case, an error is introduced. Referring to the manner of measuring the time duration of the signals shown in FIG. 27, the error in measuring the time duration of the signals by the second device can be obtained as shown in Equation (4). error = |M1 - M2| / M2 Equation (4) error represents the error, M1 represents the measured count of the time duration of the signal measured by the second device, and M2 represents the actual count of the actual clock cycles of the actual clock of the time duration of the signal. M2 is directly proportional to M.

[0282] Optionally, in the present embodiment of the present application, M is the maximum value among a plurality of values that satisfy the first condition. In other words, the larger the value of M, the smaller the error in measuring the time duration of the second signal by the second device.

[0283] Hereinafter, in order to further describe the synchronization signal of the present embodiment of the present application, some structures of the synchronization signal and the corresponding first sequence are given.

[0284] Example 1: The synchronization signal includes a first signal. The first sequence for generating the synchronization signal may be [000000000000]. Alternatively, the first sequence for generating the synchronization signal may be [000110]. Alternatively, the first sequence for generating the synchronization signal may be [001100].

[0285] Optionally, in a possible implementation, the waveform of the synchronization signal is generated in a CP-OFDM format by performing DFT transform precoding on the first sequence. The first signal may be used as a wake-up signal, and the first signal may be used to activate the second device. In other words, after the second device receives the first signal from the first device, the counter of the second device starts to operate, starts to detect the time length of the received signal, and receives and demodulates the downlink data. In other words, before the second device receives the first signal, in order to obtain the energy-saving effect, the counter of the second device may not operate and may not detect the time length of the received signal.

[0286] Example 2: The synchronization signal may include a first signal and a second signal.

[0287] Optionally, the first sequence for generating the synchronization signal may be [0000000000001111001111100]. The first signal may correspond to [000000000000] in the first sequence, and the second signal may correspond to [111100] in the first sequence. Alternatively, the second signal may correspond to [111100] at the end position of the first sequence, or the second signal may correspond to [111100] that is not at the end position of the first sequence.

[0288] Optionally, the first sequence for generating the synchronization signal may be [000000000000111111111100]. The first signal corresponds to [000000000000] in the first sequence, and the second signal corresponds to [111111111100] in the first sequence.

[0289] Optionally, the first sequence for generating the synchronization signal may be [000110111100]. The first signal may correspond to [000110] in the first sequence, and the second signal may correspond to [111100] in the first sequence.

[0290] Optionally, in the first sequence, it may be [001100111100]. The first signal may correspond to [001100] in the first sequence, and the second signal corresponds to [111100] in the first sequence.

[0291] Optionally, in a possible implementation, the waveform of the synchronization signal is generated in a CP - OFDM mode by performing DFT transform precoding on the first sequence. The first signal may be used as a wake - up signal and may be used to activate the second device. In other words, after the second device receives the first signal from the first device, the counter of the second device starts to operate, begins to detect the time duration of the received signal, and receives and demodulates the downlink data. In other words, before the second device receives the first signal, in order to obtain an energy - saving effect, the counter of the second device may not operate and may not detect the time duration of the received signal.

[0292] Optionally, in a possible implementation, the antenna port used by the first device to transmit the first signal is the same as the antenna port used by the first device to transmit the second signal.

[0293] Optionally, in a possible implementation, the antenna port used by the second device to receive the first signal is the same as the antenna port used by the second device to receive the second signal.

[0294] Optionally, in a possible implementation, the length of the CP in the OFDM symbol where the first signal is located is the same as the length of the CP in the OFDM symbol where the second signal is located.

[0295] Optionally, in a possible implementation, the CP type of the OFDM symbol where the first signal is located is the same as the CP type of the OFDM symbol where the second signal is located. For example, the CP type of the OFDM symbol where the first signal is located and the CP type of the OFDM symbol where the second signal is located are both extended CPs, or the CP type of the OFDM symbol where the first signal is located and the CP type of the OFDM symbol where the second signal is located are both normal CPs.

[0296] Optionally, in a possible implementation, the subcarrier spacing of the first signal is the same as the subcarrier spacing of the second signal.

[0297] Optionally, as shown in FIG. 11, the synchronization method according to the present embodiment of the present application may further include the following steps.

[0298] S1104: The second device transmits capability information to the first device. Correspondingly, the first device receives the capability information from the second device. In other words, the second device may report the capability information to the first device.

[0299] Optionally, the capability information may include one or more of whether the second device corresponds to energy harvesting, whether the second device corresponds to envelope detection, or whether the second device corresponds to backscatter communication.

[0300] It should be understood that for the second device to support energy harvesting means that the second device can autonomously obtain another type of energy (such as solar energy, thermoelectric energy from temperature difference, vibration energy, wind energy, or radio frequency energy) from the environment and convert that energy into electrical energy. The advantage of energy harvesting is that it can replace the battery that powers the device or supplement the energy of the battery. In this way, the lifespan of the device is extended. The energy generated in the energy harvesting mode can be provided to the signal processing or data storage circuit of the second device to maintain the normal operating state of the second device.

[0301] It should be understood that for the second device to support envelope detection means that the second device may be capable of receiving signals in the envelope detection mode. The signal may be a signal from the first device.

[0302] Envelope detection may be a signal detection method in which the envelope or amplitude line of a signal below a low frequency is obtained through half-wave or full-wave rectification of a high-frequency or intermediate-frequency input signal. In this way, after receiving a signal in the envelope detection mode, the second device may obtain the envelope of the original signal. Further, the second device may perform digital sampling on the envelope of the original signal and compare the envelope with the amplitude or energy threshold set by the second device to determine whether the received signal is 1 or 0. It is obvious that in another implementation, the second device may also determine whether the received signal is 1 or 0. This is not particularly limited in the present embodiment of this application.

[0303] For the second device to support backscatter communication means that when the second device does not have a radio frequency link for active transmission, the second device supports information transfer to the first device, or when the second device has a radio frequency link for active transmission but the link does not need to be made available, the second device supports information transfer to the first device. In other words, in this case, the second device mainly relies on an excitation device other than the first device or a continuous carrier transmitted by the first device to perform modulation. For example, the second device may reflect some or all of the incident carriers by adjusting the impedance of the antenna of the second device, or the second device may not reflect the incident carriers or absorb the energy of the incident carriers by adjusting the impedance of the antenna of the second device. In this way, the second device can modulate the digital information of the second device onto the incident carrier by adjusting the impedance of the antenna of the second device and transfer the digital information to the first device.

[0304] Optionally, in the present embodiment of the present application, the maximum bandwidth supported by the second device is limited.

[0305] Optionally, in a possible implementation, the maximum uplink bandwidth supported by the second device does not exceed X1.

[0306] For example, X1 is 20 MHz, 5 MHz, 3 MHz, 1.4 MHz, 1 MHz, 720 kHz, 540 kHz, 360 kHz, or 180 kHz.

[0307] Optionally, X1 is K1 resource blocks, and K1 is a positive integer.

[0308] For example, K1 is a positive integer not exceeding 11, a positive integer not exceeding 25, a positive integer not exceeding 51, or a positive integer not exceeding 106.

[0309] Optionally, in another possible implementation, the maximum downlink bandwidth supported by the second device does not exceed Y1.

[0310] For example, Y1 is 20 MHz, 5 MHz, 3 MHz, 1.4 MHz, 1 MHz, 720 kHz, 540 kHz, 360 kHz, or 180 kHz.

[0311] Optionally, Y1 is K2 resource blocks, where K2 is a positive integer.

[0312] For example, K2 is a positive integer not exceeding 11, a positive integer not exceeding 25, a positive integer not exceeding 51, or a positive integer not exceeding 106.

[0313] Optionally, in the present embodiment of the present application, the maximum uplink bandwidth supported by the second device is less than or equal to the maximum downlink bandwidth supported by the second device.

[0314] Optionally, in the present embodiment of the present application, the second device corresponds to a limited number of transmission antennas and / or reception antennas.

[0315] Optionally, the number of reception antennas of the second device does not exceed X2. X2 is 1, 2, or 4.

[0316] Optionally, the number of reception branches (Rx branches) of the second device does not exceed X2. X2 is 1, 2, or 4.

[0317] Optionally, the number of transmission antennas of the second device does not exceed Y2. Y2 is 1, 2, or 4.

[0318] Optionally, the number of transmission branches of the second device does not exceed Y2. Y2 is 1, 2, or 4.

[0319] Optionally, the number of transmission antennas of the second device is greater than or equal to the number of reception antennas of the second device.

[0320] Optionally, the number of transmission branches of the second device is greater than or equal to the number of reception branches of the second device.

[0321] In the present embodiment of the present application, it should be noted that the "reception branch" may also be referred to as the "number of reception radio frequency channels" or the "number of reception radio frequency chains (RF chains)", and the "transmission branch" may also be referred to as the "number of transmission radio frequency channels" or the "number of transmission radio frequency chains".

[0322] It should be noted that the second device may not perform transmission and reception simultaneously in a serving cell having a paired spectrum.

[0323] In the above embodiment, it can be understood that the method and / or steps implemented by the first device may alternatively be implemented by components (such as a processor, a chip, a chip system, a circuit, a logic module, or software) that can be used within the first device, and the method and / or steps implemented by the second device may alternatively be implemented by components (such as a processor, a chip, a chip system, a circuit, a logic module, or software) that can be used within the second device.

[0324] Above, the solutions mainly provided in this application have been described. Corresponding to this, this application further provides a communication device. The communication device is configured to implement the method of the above method embodiments. The communication device may be the first device in the method embodiments, or a device including the first device, or a component that can be used within the first device, such as a chip or a chip system, etc. Alternatively, the communication device may be the second device in the method embodiments, or a device including the second device, or a component that can be used within the second device, such as a chip or a chip system, etc.

[0325] To implement the above functions, the communication device includes a hardware structure and / or software module for executing the corresponding functions. A person skilled in the art should easily notice that in combination with the units and algorithm steps in the examples described in the embodiments disclosed in this specification, this application can be implemented by hardware or a combination of hardware and computer software. Whether the function is executed by hardware or by hardware driven by computer software depends on the individual application services of the technical solution and the design constraints. A person skilled in the art can implement the functions described in various ways according to each specific application service, but such implementation shall not be regarded as outside the scope of this application.

[0326] In the embodiments of this application, the communication device can be divided into functional modules based on the above method embodiments. For example, each functional module may be obtained by division based on each corresponding function, or two or more functions may be integrated into one processing module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. It should be noted that in the embodiments of this application, the module division is only an example and is merely a logical function division. In actual implementation, another division method may be used.

[0327] For example, the communication device is the first device in the embodiment of the above method. FIG. 28 is a diagram of the structure of the first device 280. The first device 280 includes a processing module 2801 and a transceiver module 2802.

[0328] In some embodiments, the first device 280 may further include a storage module (not shown in FIG. 28) configured to store program instructions and data.

[0329] In some embodiments, the processing module 2801 is configured to generate a synchronization signal. The transceiver module 2802 is configured to transmit the synchronization signal to a second device. The synchronization signal is generated in an OFDM format, and the synchronization signal includes a first signal and / or a second signal. The first signal is used to determine the start position of the time domain occupied by the data transmitted from the first device to the second device, and the second signal is used to determine the frequency at which the second device transmits data to the first device.

[0330] In some embodiments, the synchronization signal includes a first signal and a second signal, and the second signal is located after the first signal.

[0331] In some embodiments, the first signal and the second signal are located in the same OFDM symbol.

[0332] In some embodiments, the waveform of the synchronization signal is a CP-OFDM waveform.

[0333] In some embodiments, the waveform of the synchronization signal is generated in a CP-OFDM format based on a first sequence.

[0334] In some embodiments, the waveform of the synchronization signal is generated in a DFT transform precoding format.

[0335] In some embodiments, the fact that the waveform of the synchronization signal is generated in a DFT transform precoding pattern means that the waveform of the synchronization signal is a waveform obtained by CP-OFDM for a second sequence, and the second sequence is a sequence obtained by DFT transform precoding for a first sequence.

[0336] In some embodiments, the time-domain resources of the first signal include the first K time units among the N time units corresponding to the desired signal in one OFDM symbol, where K is a positive integer, and the desired signal in the OFDM symbol is the part that carries the desired information or desired data in the OFDM symbol.

[0337] In some embodiments, the time-domain resources of the first signal further include a part of the time units corresponding to the CP in the OFDM symbol where the first signal is located.

[0338] In some embodiments, the signal carried by the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is located is a low-level signal, the time length of the last S time units is greater than or equal to the time length of the CP of the OFDM symbol where the first signal is located, and the desired signal in the OFDM symbol is the part that carries the desired information or desired data in the OFDM symbol.

[0339] In some embodiments, the time-domain resources of the second signal include M of the N time units corresponding to the desired signal in the OFDM symbol, where M is a positive integer, and the desired signal in the OFDM symbol is the part that carries the desired information or desired data in the OFDM symbol.

[0340] In some embodiments, the synchronization signal includes a second signal, the waveform of the synchronization signal is generated in a CP-OFDM format by performing DFT transform precoding on a first sequence, the first sequence includes a third sequence, the third sequence is the sequence used to generate the second signal, and M satisfies a first condition, and the first condition includes the following.

[0341] N is L times M, and the number of elements included in the first sequence is L times the number of elements included in the third sequence, where N is a power of 2 and L is a positive integer.

[0342] In some embodiments, M is the maximum value among a plurality of values that satisfy the first condition.

[0343] In some embodiments, the transceiver module 2802 is further configured to receive capability information from a second device. The capability information includes at least one of whether the second device supports energy harvesting, whether the second device supports envelope detection, or whether the second device supports backscatter communication.

[0344] All relevant content of the steps in the embodiments of the above method can be cited in the description of the functions of the corresponding functional modules. Details will not be described again herein.

[0345] In this application, the first device 280 integrally includes functional modules obtained by division. The "module" in this specification can be an application-specific integrated circuit ASIC, a circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and / or another component that can provide the above functions.

[0346] In some embodiments, when the first device 280 is an access network device, in a hardware implementation, one of ordinary skill in the art can understand that the first device 280 may be in the form of the access network device 1010 shown in FIG. 10.

[0347] In one example, the function / implementation process of the processing module 2801 in FIG. 28 may be implemented by a processor 1011 in the access network device 1010 shown in FIG. 10 by calling computer-executable instructions stored in a memory 1012. The function / implementation process of the transceiver module 2802 in FIG. 28 may be implemented by a transceiver 1013 in the access network device 1010 shown in FIG. 10.

[0348] In some embodiments, when the first device 280 is a terminal device, in a hardware implementation, one of ordinary skill in the art can understand that the first device 280 may be in the form of the terminal device 1000 shown in FIG. 10.

[0349] In one example, the function / implementation process of the processing module 2801 in FIG. 28 may be implemented by a processor 1001 in the terminal device 1000 shown in FIG. 10 by calling computer-executable instructions stored in a memory 1002. The function / implementation process of the transceiver module 2802 in FIG. 28 may be implemented by a transceiver 1003 in the terminal device 1000 shown in FIG. 10.

[0350] In some embodiments, when the first device 280 in FIG. 28 is a chip or a chip system, the function / implementation process of the transceiver module 2802 may be implemented by an input / output interface (or communication interface) of the chip or the chip system, and the function / implementation process of the processing module 2801 may be implemented by a processor (or processing circuit) of the chip or the chip system.

[0351] The first device 280 provided in this embodiment may execute the above synchronization method. Therefore, for the technical effects that can be achieved by the first device 280, please refer to the embodiment of the above method. Details will not be described again in this specification.

[0352] For example, the communication device is the second device in the embodiment of the above method. FIG. 29 is a diagram of the structure of the second device 290. The second device 290 includes a processing module 2901 and a transceiver module 2902.

[0353] In some embodiments, the second device 290 may further include a storage module (not shown in FIG. 29) configured to store program instructions and data.

[0354] In some embodiments, the transceiver module 2902 may also be referred to as a transceiver unit and is configured to implement a transmission function and / or a reception function. The transceiver module 2902 may include a transceiver circuit, a transceiver machine, a transceiver, or a communication interface.

[0355] In some embodiments, the transceiver module 2902 may include a receiving module and a transmitting module, which are respectively configured to execute the receiving step and the transmitting step executed by the second device in the embodiments of the above method, and / or configured to support other processes of the technology described in the present application. The processing module 2901 may be configured to execute the processing (e.g., determination) step executed by the second device in the embodiments of the above method, and / or configured to support other processes of the technology described in the present application. For example, the transceiver module 2902 may be configured to receive a synchronization signal from the first device, and the processing module 2901 may be configured to perform time synchronization and / or frequency synchronization based on the synchronization signal, where the synchronization signal is generated in an OFDM format, the synchronization signal includes a first signal and / or a second signal, the first signal is used to determine the start position of the time domain occupied by the data transmitted from the first device to the second device, and the second signal is used to determine the frequency at which the second device transmits data to the first device.

[0356] In some embodiments, the synchronization signal includes a first signal and a second signal, and the second signal is located after the first signal.

[0357] In some embodiments, the first signal and the second signal are located in the same OFDM symbol.

[0358] In some embodiments, the waveform of the synchronization signal is a CP-OFDM waveform.

[0359] In some embodiments, the waveform of the synchronization signal is generated in a CP-OFDM format based on a first sequence.

[0360] In some embodiments, the waveform of the synchronization signal is generated in a DFT transform precoding format.

[0361] In some embodiments, the fact that the waveform of the synchronization signal is generated in a DFT transform precoding pattern means that the waveform of the synchronization signal is a waveform obtained by CP-OFDM for a second sequence, and the second sequence is a sequence obtained by DFT transform precoding for a first sequence.

[0362] In some embodiments, the time-domain resources of the first signal include the first K time units among the N time units corresponding to the desired signal in one OFDM symbol, where K is a positive integer, and the desired signal in the OFDM symbol is the part that carries the desired information or desired data in the OFDM symbol.

[0363] In some embodiments, the time-domain resources of the first signal further include a part of the time units corresponding to the CP in the OFDM symbol where the first signal is located.

[0364] In some embodiments, the signal carried by the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is located is a low-level signal, and the time length of the last S time units is equal to or greater than the time length of the CP of the OFDM symbol where the first signal is located, and the desired signal in the OFDM symbol is the part that carries the desired information or desired data in the OFDM symbol.

[0365] In some embodiments, the time-domain resources of the second signal include M of the N time units corresponding to the desired signal in the OFDM symbol, where M is a positive integer, and the desired signal in the OFDM symbol is the part that carries the desired information or desired data in the OFDM symbol.

[0366] In some embodiments, the synchronization signal includes a second signal, the waveform of the synchronization signal is generated in a CP-OFDM mode by performing DFT transform precoding on a first sequence, the first sequence includes a third sequence, the third sequence is the sequence used to generate the second signal, and M satisfies a first condition, and the first condition includes the following.

[0367] N is L times M, and the number of elements included in the first sequence is L times the number of elements included in the third sequence, where N is a power of 2 and L is a positive integer.

[0368] In some embodiments, M is the maximum value among a plurality of values that satisfy the first condition.

[0369] In some embodiments, the transceiver module 2902 is further configured to transmit capability information to a first device. The capability information includes at least one of whether the second device corresponds to energy harvesting, whether the second device corresponds to envelope detection, or whether the second device corresponds to backscatter communication.

[0370] All relevant contents of the steps in the embodiments of the above method can be cited in the description of the functions of the corresponding functional modules. Details will not be described again in this specification.

[0371] In this application, the second device 290 integrally includes functional modules obtained by splitting. The "module" in this specification can be an application-specific integrated circuit ASIC, a circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and / or another component that can provide the above functions.

[0372] In some embodiments, when the second device 290 is a terminal device, those skilled in the art can understand in the hardware implementation that the second device 290 may be in the form of the terminal device 1000 shown in FIG. 10.

[0373] In one example, the function / implementation process of the processing module 2901 in FIG. 29 may be implemented by the processor 1001 in the terminal device 1000 shown in FIG. 10 by calling computer-executable instructions stored in the memory 1002. The function / implementation process of the transceiver module 2902 in FIG. 29 may be implemented by the transceiver 1003 in the terminal device 1000 shown in FIG. 10.

[0374] In some embodiments, when the second device 290 in FIG. 29 is a chip or a chip system, the function / implementation process of the transceiver module 2902 may be implemented by the input / output interface (or communication interface) of the chip or chip system, and the function / implementation process of the processing module 2901 may be implemented by the processor (or processing circuit) of the chip or chip system.

[0375] The second device 290 provided in this embodiment may execute the above synchronization method. Therefore, for the technical effects that can be realized by the second device 290, please refer to the embodiments of the above method. Details will not be described again in this specification.

[0376] In some embodiments, the first device or the second device of the present application may be further implemented by one or more field programmable gate arrays (FPGAs), programmable logic devices (PLDs), control devices, state machines, gate logics, individual hardware components, any other suitable circuits, or any combination of circuits capable of performing various functions described in the present application.

[0377] In some embodiments, the present application further provides a communication device. The communication device includes a processor configured to implement the method in any one of the above method embodiments.

[0378] In a possible implementation, the communication device further includes a memory. The memory is configured to store necessary computer programs and data. The computer program may include instructions. The processor calls the instructions in the computer program stored in the memory and instructs the communication device to execute the method in any one of the above method embodiments. Obviously, the communication device may not include a memory.

[0379] In another possible implementation, the communication device further includes an interface circuit. The interface circuit is a code / data read / write interface circuit. The interface circuit is configured to receive computer-executable instructions (the computer-executable instructions may be stored in the memory and may be read directly from the memory or may be read through another component) and transmit the computer-executable instructions to the processor.

[0380] In yet another possible implementation, the communication device further includes a communication interface, and the communication interface is configured to communicate with modules other than the communication device.

[0381] It can be understood that this communication device may also be a chip or a chip system. When the communication device is a chip system, the communication system may include a chip or may include a chip and other individual components. This is not particularly limited in the embodiments of the present application.

[0382] This application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program or instructions. When the computer program or instructions are executed by a computer, the functions in any one of the above method embodiments are implemented.

[0383] This application further provides a computer program product. When the computer program product is executed by a computer, the functions in any one of the above method embodiments are implemented.

[0384] Those skilled in the art can understand that, for the convenience of description and to simplify the description, for the detailed operation processes of the above systems, devices, and units, reference may be made to the corresponding processes in the embodiments of the above methods. The details will not be described again in this specification.

[0385] It can be understood that the systems, devices, and methods described in this application may alternatively be implemented in another manner. For example, the described device embodiments are merely examples. For example, the division into units is merely a logical function division, and in actual implementation, it may be other divisions. For example, multiple units or components may be combined or integrated into another system, some features may be ignored or not executed. Furthermore, the shown or described mutual connection, direct connection, or communication connection may be implemented through some interfaces. The indirect connection or communication connection between devices or units may be implemented in an electronic form, a mechanical form, or another form.

[0386] Units described as separate components may or may not be physically separated, i.e., they may be located in one place or may be distributed across multiple network units. Components shown as units may or may not be physical units. Some or all of these units may be selected based on actual requirements to achieve the objectives of the solution of the embodiment.

[0387] Furthermore, the functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist physically independently, or two or more units may be integrated into one unit.

[0388] All or part of the above-described embodiments may be implemented by software, hardware, firmware, or any combination thereof. When a software program is used to implement an embodiment, all or part of the embodiment may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the procedures or functions of the embodiments of the present application are generated. The computer may be a general-purpose computer, a dedicated computer, a computer network, or another programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted in a wired manner (such as coaxial cable, optical fiber, or digital subscriber line (DSL)) or a wireless manner (such as infrared, wireless, or microwave) from a website, computer, server, or data center to another website, computer, server, or data center. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device such as a server or data center integrating one or more available media. The available medium may be a magnetic medium (such as a floppy disk, hard disk, or magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)), etc. In the embodiments of the present application, the computer may include the above-described devices.

[0389] Although the present application has been described with reference to embodiments, those skilled in the art can understand and implement other variants of the disclosed embodiments by referring to the accompanying drawings, the disclosed content, and the appended claims in the process of implementing the present application for which protection is claimed. In the claims, "comprising" does not exclude another component or another step, and "a" or "one" does not exclude the case where it is plural. A single processor or another unit may implement several functions listed in the claims. Although some means are recorded in different independent claims, this does not mean that it is impossible to combine them to produce better effects.

[0390] Although the present application has been described with reference to its specific features and embodiments, it is obvious that various modifications and combinations can be made to them without departing from the scope of the present application. Therefore, the present specification and the accompanying drawings are merely exemplary descriptions of the present application defined by the appended claims, and are regarded as covering any or all of the modifications, variations, combinations, or equivalents of the present application. It is obvious that those skilled in the art can make various modifications and variations to the present application without departing from the scope of the present application. The present application is intended to cover these modifications and variations of the present application provided that they are included within the scope of protection defined by the following claims and their equivalent technologies.

Claims

1. A synchronization method, the method comprising: generating, by a first device, a synchronization signal, wherein the synchronization signal is generated in an orthogonal frequency division multiplexing (OFDM) format, the synchronization signal includes a first signal and / or a second signal, the first signal is used to determine a time domain start position occupied by data transmitted from the first device to a second device, and the second signal is used to determine a frequency at which the second device transmits data to the first device; transmitting, by the first device, the synchronization signal to the second device; A synchronization method comprising the above.

2. The method according to claim 1, wherein the synchronization signal includes the first signal and the second signal, and the second signal is after the first signal.

3. The method according to claim 2, wherein the first signal and the second signal are arranged in the same OFDM symbol.

4. The method according to any one of claims 1 to 3, wherein the waveform of the synchronization signal is a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform.

5. The method according to claim 4, wherein the waveform of the synchronization signal is generated in a CP-OFDM format based on a first sequence.

6. The method according to claim 4 or 5, wherein the waveform of the synchronization signal is generated in a discrete Fourier transform (DFT) precoding format.

7. The fact that the waveform of the synchronization signal is generated in a discrete Fourier transform (DFT) precoding format includes that the waveform of the synchronization signal is a waveform obtained through CP-OFDM for a second sequence, and the second sequence is a sequence obtained through DFT precoding for the first sequence. The method according to claim 6.

8. The method according to any one of claims 1 to 7, wherein the time domain resources of the first signal include the first K time units among N time units corresponding to a desired signal in one OFDM symbol, K is a positive integer, and the desired signal in the OFDM symbol is a part other than the cyclic prefix (CP) in the OFDM symbol.

9. The method according to claim 8, wherein the time domain resource of the first signal further includes a part of the time units corresponding to the CP in the OFDM symbol where the first signal is arranged.

10. The signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol where the first signal is arranged is a low-level signal. The time length of the last S time units is equal to or greater than the time length of the CP in the OFDM symbol where the first signal is arranged. The desired signal in the OFDM symbol is the part other than the CP in the OFDM symbol. The method according to any one of claims 1 to 9.

11. The time domain resource of the second signal includes M of the N time units corresponding to the desired signal in the OFDM symbol, where M is a positive integer. The desired signal in the OFDM symbol is the part other than the CP in the OFDM symbol. The method according to any one of claims 1 to 10.

12. The synchronization signal includes the second signal. The waveform of the synchronization signal is generated in the CP-OFDM format by performing the DFT transform precoding on the first sequence. The first sequence includes a third sequence, and the third sequence is the sequence used to generate the second signal. M satisfies a first condition, and the first condition is N is L times M, and the number of elements included in the first sequence is L times the number of elements included in the third sequence, where N is a power of 2 and L is a positive integer. The method according to claim 11.

13. M is the maximum value among a plurality of values that satisfy the first condition. The method according to claim 12.

14. A step of receiving a synchronization signal from a first device by a second device, wherein the synchronization signal is generated in an orthogonal frequency division multiplexing (OFDM) mode, the synchronization signal includes a first signal and / or a second signal, the first signal is used to determine a start position occupied by data transmitted from the first device to the second device, and the second signal is used to determine a frequency at which the second device transmits data to the first device. A step of performing time synchronization and / or frequency synchronization based on the synchronization signal by the second device A synchronization method comprising the above.

15. The method according to claim 14, wherein the synchronization signal includes the first signal and the second signal, and the second signal is after the first signal.

16. The method according to claim 15, wherein the first signal and the second signal are arranged in the same OFDM symbol.

17. The method according to any one of claims 14 to 16, wherein a waveform of the synchronization signal is a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform.

18. The method according to claim 17, wherein the waveform of the synchronization signal is generated in a CP-OFDM mode based on a first sequence.

19. The method according to claim 17 or 18, wherein the waveform of the synchronization signal is generated in a discrete Fourier transform (DFT) precoding mode.

20. The fact that the waveform of the synchronization signal is generated in a discrete Fourier transform (DFT) precoding mode The method according to claim 19, wherein the waveform of the synchronization signal is a waveform obtained through CP-OFDM for a second sequence, and the second sequence is a sequence obtained through DFT precoding for the first sequence.

21. The time domain resource of the first signal includes first K time units among N time units corresponding to a desired signal in one OFDM symbol, K is a positive integer, and the desired signal in the OFDM symbol is a part other than the CP in the OFDM symbol. The method according to any one of claims 14 to 20.

22. The method according to claim 21, wherein the time-domain resource of the first signal further includes a part of the time units corresponding to the CP in the OFDM symbol in which the first signal is arranged.

23. The signal carried in the last S time units among the N time units corresponding to the desired signal in the OFDM symbol in which the first signal is arranged is a low-level signal, and the time length of the last S time units is not less than the time length of the CP in the OFDM symbol in which the first signal is arranged, and the desired signal in the OFDM symbol is the part other than the CP in the OFDM symbol. The method according to any one of claims 14 to 22.

24. The time-domain resource of the second signal includes M of the N time units corresponding to the desired signal in the OFDM symbol, M is a positive integer, and the desired signal in the OFDM symbol is the part other than the CP in the OFDM symbol. The method according to any one of claims 14 to 23.

25. The synchronization signal includes the second signal, and the waveform of the synchronization signal is generated in the CP-OFDM mode by performing the DFT transform precoding on the first sequence. The first sequence includes a third sequence, and the third sequence is a sequence used to generate the second signal. M satisfies a first condition, and the first condition is N is L times M, and the number of elements included in the first sequence is L times the number of elements included in the third sequence, N is a power of 2, and L is a positive integer. The method according to claim 24.

26. M is the maximum value among a plurality of values that satisfy the first condition. The method according to claim 25.

27. A communication device, wherein the communication device is configured to execute the synchronization method according to any one of claims 1 to 13.

28. A communication device, wherein the communication device is configured to execute the synchronization method according to any one of claims 14 to 26.

29. A communication device including a processor, the processor being coupled to a memory, The processor is configured to execute a computer program stored in the memory to enable the communication device to execute the synchronization method according to any one of claims 1 to 26.

30. A communication device including a processor and an interface circuit, The interface circuit is configured to receive code instructions and transmit the code instructions to the processor, The processor is configured to execute the code instructions to execute the method according to any one of claims 1 to 26.

31. A communication device including a processor and a transceiver, the transceiver being used for information exchange between the communication device and another communication device, and the processor being configured to execute program instructions to execute the synchronization method according to any one of claims 1 to 26.

32. A computer-readable storage medium including a computer program or instructions, when the computer program or the instructions are executed on a computer, the computer is enabled to execute the synchronization method according to any one of claims 1 to 26.

33. A computer program product including a computer program or instructions, when the computer program or the instructions are executed on a computer, the computer is enabled to execute the synchronization method according to any one of claims 1 to 26.

34. A synchronization method, the method comprising: ​ A step of generating a synchronization signal by a first device, wherein the synchronization signal is generated in an orthogonal frequency division multiplexing (OFDM) mode, the synchronization signal includes a first signal and / or a second signal, the first signal is used to determine a time domain start position occupied by data transmitted from the first device to a second device, and the second signal is used to determine a frequency at which the second device transmits data to the first device. A step of transmitting the synchronization signal from the first device to the second device by the first device. A step of receiving the synchronization signal from the first device by the second device. A step of performing time synchronization and / or frequency synchronization based on the synchronization signal by the second device A synchronization method comprising the above steps. **Claim 35** A communication system comprising a first device and a second device, wherein the first device is configured to implement the synchronization method according to any one of claims 1 to 13, and the second device is configured to implement the synchronization method according to any one of claims 14 to 26.

Images