WO2023241407A1 - 同步方法及通信装置 - Google Patents

同步方法及通信装置 Download PDF

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Publication number
WO2023241407A1
WO2023241407A1 PCT/CN2023/098657 CN2023098657W WO2023241407A1 WO 2023241407 A1 WO2023241407 A1 WO 2023241407A1 CN 2023098657 W CN2023098657 W CN 2023098657W WO 2023241407 A1 WO2023241407 A1 WO 2023241407A1
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Prior art keywords
signal
synchronization
sequence
ofdm symbol
synchronization signal
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PCT/CN2023/098657
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English (en)
French (fr)
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罗之虎
陈俊
吴毅凌
金哲
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华为技术有限公司
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Publication of WO2023241407A1 publication Critical patent/WO2023241407A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/0005—Synchronisation arrangements synchronizing of arrival of multiple uplinks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes

Definitions

  • the present application relates to the field of communications, and in particular to synchronization methods and communications devices.
  • IoT Internet-of-things
  • the 3rd generation partnership project (3GPP) plans to enable the fifth generation (5th generation, 5G) system or new radio (NR) system to support Passive IoT in version 18 (reversion18, R18) Or low-power communication systems such as ambient power-enabled IoT.
  • 5G fifth generation
  • NR new radio
  • low-power communication systems such as ambient power-enabled IoT.
  • the compatibility of the synchronization signal with the NR system is not considered. Therefore, when the synchronization signal of the low-power communication system is directly applied to the NR system, the time domain waveform of the synchronization signal is different from that of the NR system. There is interference between the time domain waveforms of the subcarriers of the NR system.
  • the synchronization method and communication device provided by the embodiments of this application can make the synchronization signal of the low-power communication system synchronize with the subcarriers of the NR system when the NR system introduces low-power communication systems such as Passive IoT or ambient power-enabled IoT. coexist.
  • the first aspect provides a synchronization method.
  • the method can be executed by the first device, or by a component of the first device, such as the processor, chip, or chip system of the first device. It can also be executed by a device that can realize all Or the logic module or software implementation of part of the first device function.
  • the following description takes the method being executed by the first device as an example.
  • the method includes: a first device generating a synchronization signal and sending the synchronization signal to a second device.
  • the synchronization signal is generated by orthogonal frequency division multiplexing OFDM
  • the synchronization signal includes a first signal and/or a second signal.
  • the first signal is used to determine the signal sent by the first device to the second device.
  • the second signal is used to determine the frequency of data sent by the second device to the first device. Since the synchronization signal is generated by OFDM, the time domain waveform of the synchronization signal can be the waveform after superposition of multiple orthogonal subcarriers. Therefore, 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. Therefore, when a low-power communication system such as Passive IoT or ambient power-enabled 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.
  • a low-power communication system such as Passive IoT or ambient power-enabled IoT
  • a synchronization method is provided.
  • the method can be executed by the second device, or by a component of the second device, such as the processor, chip, or chip system of the second device. It can also be executed by a device that can realize all Or the logic module or software implementation of part of the second device function.
  • the following description takes the method being executed by the second device as an example.
  • the method includes: the second device receives a synchronization signal from the first device, and performs time synchronization and/or frequency synchronization according to the synchronization signal.
  • the synchronization signal is generated by orthogonal frequency division multiplexing OFDM, and the synchronization signal includes a first signal and/or a second signal.
  • the first signal is used to determine whether the first device sends a signal to the second device.
  • the starting position occupied by the data the second signal is used to determine the frequency of data sent by the second device to the first device.
  • the synchronization signal is generated by OFDM, so that the synchronization signal and the OFDM subcarriers of the data sent by the first device to the second device are orthogonal to each other.
  • the time domain waveform of the synchronization signal can be compared with the OFDM subcarrier.
  • the time domain waveforms of the OFDM subcarriers of the data sent by the first device are completely separated to avoid interference. Therefore, when the NR system introduces low-power communication systems such as Passive IoT or ambient power-enabled IoT, the synchronization signals of the low-power communication system can coexist with the subcarriers of the NR system.
  • the synchronization signal includes the first signal and the second signal, wherein the second signal is located 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 length of the second signal, and then calculate the BLF based on the DR carried in the downlink data.
  • the first signal and the second signal are located in the same OFDM symbol. Based on this solution, after the second device detects the first signal, it can determine to start receiving the second signal.
  • the waveform of the synchronization signal is an orthogonal frequency division multiplexing CP-OFDM waveform using a cyclic prefix.
  • the waveform of the synchronization signal is generated based on the first sequence through CP-OFDM.
  • the waveform of the synchronization signal is generated by discrete Fourier transform (DFT) precoding.
  • DFT discrete Fourier transform
  • the waveform of the synchronization signal is generated by discrete Fourier transform DFT transform precoding, including: the waveform of the synchronization signal is a second sequence The waveform obtained after CP-OFDM, wherein the second sequence is a sequence obtained by performing DFT transform precoding on the first sequence.
  • the time domain resource of the first signal includes the first K time units among the N time units corresponding to the useful signal in an OFDM symbol, and K is A positive integer, where the useful signal in the OFDM symbol is the part of the OFDM symbol excluding the cyclic prefix CP.
  • the second device can detect the first signal before the second signal and downlink data, so as to facilitate the reception of subsequent downlink data and the second signal.
  • the first signal only occupies part of the time domain resources of the OFDM symbol, so the idle time domain resources in the OFDM symbol can be used to transmit other content, such as the second signal, data 0, Or RTcal, etc.
  • the time domain resource of the first signal also includes a partial time unit corresponding to the CP in the OFDM symbol in which the first signal is located.
  • the time domain corresponding to the CP is added to the time domain resource of the first signal.
  • the interval unit makes the duration of the low-level signal long enough, so that 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 the second device receives the signal, it can determine that the low-level signal with the longest duration in the received signal is the first signal.
  • the signal carried on the last S time units among the N time units corresponding to the useful signal in the OFDM symbol where the first signal is located is low power. flat signal, wherein the time length of the last S time units is greater than or equal to the time length of the CP in the OFDM symbol where the first signal is located, and the useful signal in the OFDM symbol is the part of the OFDM symbol other than the CP. . That is to say, the signal carried in the last S time units corresponding to the useful signal in the OFDM symbol where the first signal is located is a low-level signal, which can ensure that the level of the CP signal is low-level. In this way, the duration of the low level part of the first signal can be increased.
  • the time domain resource of the second signal includes M time units among the N time units corresponding to the useful signal in an OFDM symbol, where M is positive Integer, the useful signal in an OFDM symbol is the part of an OFDM symbol except CP.
  • the synchronization signal includes the second signal, wherein the waveform of the synchronization signal is obtained by performing DFT transform precoding on the first sequence and using CP- Generated by OFDM, the first sequence includes a third sequence, the third sequence is a sequence used to generate the second signal; M satisfies the first condition, the first condition includes: N is L times of M, and The number of elements contained in the first sequence is L times the number of elements contained in the third sequence, where N is a power of 2 and L is a positive integer.
  • M is the maximum value among multiple values that satisfy the first condition.
  • the method further includes: the first device receiving capability information from the second device, the capability information including at least one of the following: whether the second device supports energy harvesting; Whether the second device supports envelope detection, or whether the second device supports backscatter communications.
  • the method further includes: the second device sending capability information to the first device, the capability information including at least one of the following: whether the second device supports energy harvesting; Whether the device supports envelope detection, or whether the second device supports backscatter communications.
  • a communication device for implementing the various methods mentioned above.
  • the communication device may be the first device in the above-mentioned first aspect, or a device including the above-mentioned first device, or a device included in the above-mentioned first device, such as a chip; or the communication device may be the device in the above-mentioned second aspect.
  • the communication device includes corresponding modules, units, or means (means) for implementing the above method.
  • the modules, units, or means can be implemented by hardware, software, or by hardware executing corresponding software.
  • the hardware or software includes one or more modules or units corresponding to the above functions.
  • the communication device may include a processing module and a transceiver module.
  • the transceiver module which may also be called a transceiver unit, is used to implement the sending and/or receiving functions in any of the above aspects and any possible implementation manner thereof.
  • the transceiver module can be composed of a transceiver circuit, a transceiver, a transceiver or a communication interface.
  • This processing module can be used to implement the processing functions in any of the above aspects and any possible implementation manner thereof.
  • the transceiver module includes a sending module and a receiving module, respectively used to implement any of the above.
  • the send and receive functions on the one hand and in any possible implementation thereof.
  • a fourth aspect provides a communication device, including: a processor and a memory; the memory is used to store computer instructions, and when the processor executes the instructions, the communication device performs the method described in any of the above aspects.
  • the communication device may be the first device in the above-mentioned first aspect, or a device including the above-mentioned first device, or a device included in the above-mentioned first device, such as a chip; or the communication device may be the device in the above-mentioned second aspect.
  • a communication device including: a processor and a communication interface; the communication interface is used to communicate with modules external to the communication device; the processor is used to execute computer programs or instructions to enable the communication device Perform any of the methods described above.
  • the communication device may be the first device in the above-mentioned first aspect, or a device including the above-mentioned first device, or a device included in the above-mentioned first device, such as a chip; or the communication device may be the device in the above-mentioned second aspect.
  • a sixth aspect provides a communication device, including: at least one processor; the processor is configured to execute a computer program or instructions stored in a memory, so that the communication device executes the method described in any of the above aspects.
  • the memory may be coupled to the processor, or may be independent of the processor.
  • the communication device may be the first device in the above-mentioned first aspect, or a device including the above-mentioned first device, or a device included in the above-mentioned first device, such as a chip; or the communication device may be the device in the above-mentioned second aspect.
  • a computer-readable storage medium In a seventh aspect, a computer-readable storage medium is provided. Computer programs or instructions are stored in the computer-readable storage medium. When run on a communication device, the communication device can perform the method described in any of the above aspects. .
  • An eighth aspect provides a computer program product containing instructions that, when run on a communication device, enables the communication device to perform the method described in any of the above aspects.
  • a ninth aspect provides a communication device (for example, the communication device may be a chip or a chip system).
  • the communication device includes a processor for implementing the functions involved in any of the above aspects.
  • the communication device includes a memory for storing necessary program instructions and data.
  • the device when it is a system-on-a-chip, it may be composed of a chip or may include chips and other discrete components.
  • the communication device provided in any one of the third to ninth aspects is a chip
  • the above-mentioned sending action/function can be understood as output
  • the above-mentioned receiving action/function can be understood as input.
  • the technical effects brought by any one of the design methods in the third aspect to the ninth aspect can be referred to the technical effects brought by the different design methods in the first aspect or the second aspect, and will not be described again here.
  • a tenth aspect provides a communication system, which includes the first device described in the above aspect and the second device described in the above aspect.
  • Figure 1 is a schematic architectural diagram of a backscatter communication system provided by an embodiment of the present application
  • FIG. 2 is a schematic architectural diagram of an ultra-high frequency radio frequency identification system provided by an embodiment of the present application
  • Figure 3 is a schematic architectural diagram of a communication system based on a wake-up mechanism provided by an embodiment of the present application
  • Figure 4 is a schematic diagram of the PIE symbols of data 0 and the PIE symbols of data 1 provided by the embodiment of the present application;
  • Figure 5 is a schematic diagram of the frame structure of the downlink signal of the radio frequency identification system provided by the embodiment of the present application.
  • Figure 6 is a schematic diagram of PIE symbols using the preamble as the frame header provided by the embodiment of the present application.
  • Figure 7 is a schematic diagram of the PIE symbol using the frame synchronization code as the frame header provided by the embodiment of the present application.
  • Figure 8 is a schematic architectural diagram of a communication system provided by an embodiment of the present application.
  • Figure 9 is a schematic diagram of another communication system architecture provided by an embodiment of the present application.
  • FIG. 10 is a schematic diagram of the hardware structure of the terminal equipment and access network equipment provided by this application.
  • Figure 11 is a schematic flow chart of the synchronization method provided by the embodiment of the present application.
  • Figure 12 is a schematic diagram of time domain resources of a synchronization signal provided by an embodiment of the present application.
  • Figure 13 is a schematic diagram of time domain resources of another synchronization signal provided by an embodiment of the present application.
  • Figure 14 is a schematic diagram of time domain resources of another synchronization signal provided by an embodiment of the present application.
  • Figure 15 is a schematic structural diagram of an OFDM symbol provided by an embodiment of the present application.
  • Figure 16 is a schematic diagram of time domain resources of another synchronization signal provided by an embodiment of the present application.
  • Figure 17 is a schematic diagram of the time domain position relationship between a first signal and a second signal provided by an embodiment of the present application.
  • Figure 18 is a schematic diagram of another time domain position relationship between a first signal and a second signal provided by an embodiment of the present application.
  • Figure 19 is a schematic diagram of a module framework of a synchronization signal waveform generation method provided by an embodiment of the present application.
  • Figure 20 is a schematic diagram of a module framework of another synchronization signal waveform generation method provided by an embodiment of the present application.
  • Figure 21 is a schematic diagram of the time domain resources of the first signal provided by the embodiment of the present application.
  • Figure 22 is a schematic structural diagram of a downlink signal provided by an embodiment of the present application.
  • Figure 23 is a schematic diagram of the time length of each OFDM symbol in a time slot of the NR system provided by the embodiment of the present application;
  • Figure 24 is a schematic diagram of the value ranges of the first threshold and the second threshold provided by the embodiment of the present application.
  • Figure 25 is a schematic diagram of time domain resources of a second signal provided by an embodiment of the present application.
  • Figure 26 is a schematic diagram of time domain resources of another downlink signal provided by an embodiment of the present application.
  • Figure 27 is a schematic diagram of the clock counting measurement signal time length provided by the embodiment of the present application.
  • Figure 28 is a schematic structural diagram of a first device provided by an embodiment of the present application.
  • Figure 29 is a schematic structural diagram of a second device provided by an embodiment of the present application.
  • IoT is "the Internet of things connected”. It extends the client side of the Internet to any item and allows information exchange and communication between any item and item. This type of communication is also called machine type communications (MTC). Among them, the communication node is called MTC terminal or MTC device.
  • Typical IoT services include: smart grid, environmental monitoring, smart agriculture, smart meter reading and other services.
  • IoT requires the deployment of a large number of MTC terminals. It only requires that MTC terminals can be obtained and used at a low cost, and that the MTC terminals can be used for a long time.
  • MTC terminals are powered by batteries.
  • the limited capacity of the battery and the power consumption of the MTC terminal itself limit the use time of the MTC terminal, which increases the difficulty and cost of maintaining the MTC terminal, thus restricting the development of IoT.
  • low-power communication technologies such as wireless power transmission technology, envelope detection and demodulation technology, or reflection and scattering modulation can be used in IoT.
  • backscatter communication technology is a type of low-power communication technology and has the characteristics of low cost and ultra-low power consumption. Therefore, backscatter communication technology can increase the usage time of MTC terminals.
  • Backscatter communication technology is a communication technology based on wireless power transmission, envelope detection demodulation and reflection scattering modulation technology.
  • Figure 1 illustrates the architecture diagram of the backscatter communication system involved in the embodiment of the present application.
  • the backscatter communication system may include: an exciter 101 , a receiver 102 , and a reflector 103 .
  • the communication links of the backscatter communication system include: downlink and uplink.
  • the downlink may refer to the communication link through which the exciter 101 sends signals to the reflector 103 .
  • An uplink may refer to the communication link through which reflector 103 sends signals to receiver 102 .
  • the exciter 101 and the receiver 102 can be deployed in the same device, or the exciter 101 and the receiver 102 can be separated.
  • the reflector 103 can be divided into a passive reflector and a semi-passive reflector according to whether it is powered by a battery.
  • the passive reflector itself does not have a battery power supply, and since the downlink signal sent by the exciter 101 is a radio frequency signal, the passive reflector needs to rectify the downlink signal sent by the exciter 101 and use the rectified DC signal output as a power source, and then Powers the internal circuitry of the passive reflector. Since the semi-passive transmitter has its own battery, the semi-passive transmitter does not rely on the downlink signal sent by the exciter 101 for power supply.
  • the exciter 101 can use amplitude shift keying (ASK) to modulate the downlink signal, and the reflector 103 can use an envelope detector based on low power consumption to demodulate the downlink signal.
  • ASK amplitude shift keying
  • the reflector 103 can change the load of the antenna based on the information bits to be sent, so that the information bits can be modulated onto the incident carrier (i.e., the downlink signal), and then reflect the downlink signal to the receiver 102, thereby achieving Wireless transmission of uplink signals.
  • the reflector 103 does not require high-power consumption devices such as radio frequency oscillators, power amplifiers, and low-noise amplifiers, so that the backscatter communication system has the characteristics of low cost and ultra-low power consumption.
  • the following combines the above-mentioned backscatter communication technology, taking the ultra-high frequency (UHF) radio frequency identification (RFID) system as an example to illustrate the architecture of a communication system that combines IoT and backscatter communication technology. .
  • UHF ultra-high frequency
  • RFID radio frequency identification
  • FIG 2 illustrates the UHF RFID system architecture diagram involved in the embodiment of this application.
  • the UHF RFID system may include: reader 201 and tag 202.
  • the UHF RFID system arranges the exciter 101 and the receiver 102 shown in Figure 1 in the same device, that is, the reader 201 can include the exciter 101 and the receiver 102.
  • the tag 202 in the UHF RFID system may be the reflector 103 shown in Figure 1.
  • the reader/writer 201 and the tag 202 may also be called MTC terminals or MTC devices.
  • the communication link of the UHF RFID system also includes downlink and uplink.
  • Downlink can Refers to the communication link through which the reader/writer 201 sends signals to the tag 202.
  • the uplink may refer to the communication link through which the tag 202 sends signals to the reader 201 .
  • the reader/writer 201 sends a downlink signal to the tag 202.
  • Downlink signals may include downlink excitation signals and data.
  • the downlink excitation signal can be used to provide energy to the tag 202 .
  • the data may be used to transmit downlink signaling to the tag 202, and for the tag 202 to send uplink signals to the reader 201 using backscatter technology.
  • the reader/writer 201 can identify the identity (ID) of the tag 202 by sending downlink signals and receiving uplink signals, and then performs read or write operations on the tag 202.
  • ID identity
  • the information carried in the data can include: command words, divide ratio (DR), encoding method, select command (select) configuration parameters, or session layer (session) wait.
  • data may refer to the data that the sender needs to send to the receiver. This data can be called valid data, or useful data. In other words, “data”, “valid data”, or “useful data” can be expressed interchangeably. They are explained uniformly here and will not be described again below.
  • the communication system based on the wake-up mechanism can also reduce the power consumption of the MTC terminal, thereby increasing the usage time of the MTC terminal.
  • Figure 3 illustrates the architecture diagram of the communication system based on the wake-up mechanism involved in the embodiment of the present application.
  • the communication system based on the wake-up mechanism may include: a network device 301 and a terminal device 302.
  • the network device 301 and the terminal device 302 may also be called MTC terminals or MTC devices.
  • the terminal device 302 can be in power saving mode (PSM) or sleep mode
  • the network device 301 can send a downlink wake-up signal (wake-up signal, WUS) to the terminal device 302 in PSM or sleep mode. , notifying the terminal device 302 to send and receive data, thereby achieving the energy saving effect of the terminal device 302.
  • PSM power saving mode
  • WUS downlink wake-up signal
  • the network device 301 may be an access network device in the NR system.
  • the network device 301 may be the reader/writer 201 in the UHF RFID system.
  • the modulation method of the wake-up signal may adopt on-off keying (OOK) or ASK, so that the terminal device 302 can demodulate the downlink signal sent by the network device 301 based on a low-power envelope detector.
  • OSK on-off keying
  • ASK ASK
  • the above-mentioned backscatter communication technology can be combined with a wake-up mechanism.
  • the tag 202 in Figure 2 can be in PSM or sleep mode, and the reader 201 can send a wake-up signal to the tag 202 in PSM or sleep mode.
  • Notification tag 202 sends and receives data.
  • the above-mentioned communication system based on backscatter communication technology and the communication system based on the wake-up mechanism are usually asynchronous systems, that is, there is no time synchronization between the reader/writer 201 and the tag 202, or there is no time synchronization between the network device 301 and the terminal device 302. Time synchronization. Therefore, a preamble or synchronization signal needs to be inserted before the data of the downlink signal so that the tag 202 or the terminal device 302 can complete the detection and synchronization of the downlink signal.
  • PIE pulse interval encoding
  • FIG. 4 illustrates the PIE symbols of data 0 (data-0) and the PIE symbols of data 1 (data-1).
  • the time length T data-0 of data 0 is type A reference interval (Tari).
  • the length of time of the low level is the pulse width (PW).
  • the time length T data-1 of data 1 ranges from [1.5Tari, 2Tari], in which the low-level length is PW.
  • the value range of Tari is [6.25 ⁇ s, 25 ⁇ s]
  • the value range of PW is [max(0.265Tari, 2 ⁇ s), 0.525Tari]
  • max() means taking the maximum value.
  • time length is the same as the meaning of “duration”, and they are both expressed as the length of time occupied by a signal, symbol, or level in the time domain.
  • “duration” and “length of time” can be expressed interchangeably, and are explained uniformly here, and will not be described again below.
  • the downlink signal of the RFID system needs to insert a preamble or synchronization signal before the data of the downlink signal.
  • the ISO/IEC 18000-6C standard stipulates how to insert a preamble or synchronization signal before the data of the downlink signal, as follows:
  • the frame structure of the downlink signal of the RFID system may include: frame header 501, downlink data 502, and check code 503.
  • the frame header 501 is a synchronization signal, which is used by the tag 202 to complete the detection and synchronization of downlink signals.
  • Downlink data 502 is used to carry downlink signaling.
  • Check code 503 is used to detect whether errors occur during data transmission. Among them, the check code 503 can use a 5-bit cyclic redundancy check (CRC) code or a 16-bit CRC code.
  • CRC cyclic redundancy check
  • the frame header 501 may use a preamble code or a frame synchronization (Frame-Sync) code.
  • a preamble code For example, if the downlink signaling sent by the reader/writer 201 is a query command, the reader/writer 201 can use the preamble as the frame header. If the reader/writer 201 sends commands other than the query command, the reader/writer 201 can use the frame synchronization code as the frame header.
  • the preamble is used as a PIE symbol diagram of the frame header 501.
  • the PIE symbols of the preamble can include: delimiter, data 0, reader-tag calibration (RTcal), and tag-reader calibration (TRcal ).
  • the delimiter is used to indicate the time domain starting position of the downlink data 502 of the downlink signal.
  • the delimiter is a continuous low-level signal.
  • the time length T delimiter of the delimiter is 12.5 ⁇ s, and the tolerance is within the range of 5%, that is, the value range of the time length T delimiter of the delimiter is [0.95 ⁇ 12.5 ⁇ s, 1.05 ⁇ 12.5 ⁇ s].
  • RTcal can be used as a reference for the tag 202 to decode the PIE symbols.
  • the time length T of RTcal is the sum of the time length Tari of data 0 and the time length T data-1 of data 1, that is, the time length T of RTcal.
  • the value range of RTcal is [2.5Tari, 3Tari].
  • the tag 202 can determine that the PIE symbol is data 0; when the time length of the PIE symbol is greater than half of the time length T RTcal of RTcal, the tag 202 202 can determine that the PIE symbol is data 1.
  • TRcal is used to calculate the uplink backscatter-link frequency (BLF) of the data sent by the tag 202 to the reader 201 in combination with the DR.
  • DR is carried by the downlink data 502 in the query command.
  • DR can take the value 8 or 64/3.
  • label 202 can calculate BLF according to the following formula (1):
  • T TRcal represents the time length of TRcal.
  • the value range of T TRcal is [1.1T RTcal , 3T RTcal ].
  • the frame synchronization code is used as a PIE symbol diagram of the frame header 501.
  • the PIE symbols of the frame synchronization code may include: delimiter, data 0, and RTcal.
  • the configuration of the delimiter, data 0, and RTcal of the PIE symbol of the frame synchronization code can refer to the above-mentioned delimiter, data 0, and RTcal of the PIE symbol of the preamble, which will not be described again here.
  • low-power communication systems such as passive IoT or ambient power-enabled IoT can be A communication system with one of the following technologies: energy harvesting technology, envelope detection demodulation technology, or backscatter modulation technology.
  • the low-power communication system can be an asynchronous communication system, that is, the transmitter device and the receiver device are not strictly synchronized. Therefore, relevant organizations such as ISO or IEC have defined relevant specifications for synchronization signals in downlink signals for the receiver device. Complete the detection and synchronization of downlink signals.
  • OFDM orthogonal frequency division multiplexing
  • OFDM technology is a multi-carrier transmission technology.
  • the principle of OFDM technology is to divide multiple sub-channels in the frequency domain, convert the data to be transmitted from serial to parallel, and obtain multiple sets of data for parallel transmission. Then each set of data is modulated Transmit on the subcarrier of each subchannel. Therefore, in the time domain, the data to be transmitted is transmitted through multiple subcarriers superimposed in space. The multiple subcarriers are orthogonal to each other. When receiving the signal, the multiple subcarriers can be separated, and then each subcarrier is processed separately. Demodulate to obtain the data to be transmitted.
  • T s 1/( ⁇ f ref ⁇ N f,ref )
  • ⁇ f ref 15 ⁇ 10 3 Hz
  • N f,ref 2048.
  • the transmission parameter set supported by the NR system is shown in Table 1.
  • the first column configures ⁇ for the subcarrier space (SCS)
  • the second column represents the subcarrier spacing
  • the third column represents the cyclic prefix (CP).
  • l is the number of OFDM symbols within a subframe.
  • one frame may include subframe #0 to subframe #9.
  • the number of consecutive OFDM symbols in each subframe is
  • Each frame is divided into two equal-sized fields, field #0 and field #1.
  • Each half-frame includes five subframes. For example, half frame #0 consists of subframe #0 to subframe #4, and half frame #1 consists of subframe #5 to subframe #9.
  • slots are numbered in ascending order within a subframe by and numbered in ascending order within a frame arrangement.
  • time slot there are consecutive OFDM symbols, where Values depend on CP as shown in Tables 2 and 3.
  • timeslot in a subframe starts with the OFDM symbol in the same subframe The start of is aligned in time. For example, when one time slot includes 14 OFDM symbols, the OFDM symbols can be ordered in time order as: OFDM symbol #0 ⁇ OFDM symbol #13.
  • OFDM symbols in a time slot may include three types: downlink symbols, uplink symbols and flexible symbols.
  • Uplink symbols can only be used for uplink transmission.
  • Downlink symbols can only be used for downlink transmission.
  • Flexible symbols have no determined transmission direction and can be used for uplink transmission or downlink transmission according to the instructions of control signaling.
  • the key is that the time domain waveforms of multiple subcarriers can be completely separated and do not interfere with each other when receiving signals.
  • the time domain waveform of the synchronization signal (frame header 501) used in the above-mentioned low-power communication system is different from the data transmitted in the NR system.
  • the time domain waveforms of the subcarriers are not orthogonal to each other. If the synchronization signal used in the RFID system is directly applied to the NR system, the synchronization signal and the subcarriers transmitting data in the NR system will interfere with each other, affecting communication performance.
  • the embodiments of this application provide a synchronization method that can enable low-power communication such as Passive IoT or ambient power-enabled IoT when the NR system introduces low-power communication systems such as Passive IoT or ambient power-enabled IoT.
  • the synchronization signal of the system coexists with the subcarriers of the NR system.
  • At least one of the following or similar expressions thereof refers to any combination of these items, including any combination of a single item (items) or a plurality of items (items).
  • at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple .
  • words such as “first” and “second” are used to distinguish identical or similar items with basically the same functions and effects. Those skilled in the art can understand that words such as “first” and “second” do not limit the number and execution order, and words such as “first” and “second” do not limit the number and execution order.
  • the technical solutions of the embodiments of this application can be applied to NR systems.
  • the technical solutions of the embodiments of this application can also be applied to other communication systems.
  • LTE long term evolution
  • FDD frequency division duplex
  • TDD time division duplex
  • UMTS universal mobile telecommunication system
  • WiMAX global interoperability for microwave access
  • the NR system involved in this application includes a non-standalone (NSA) NR system or a standalone (SA) NR system.
  • SA standalone
  • the technical solution provided by this application can also be applied to future communication systems, such as the sixth generation mobile communication system.
  • the communication system can also be a public land mobile network (PLMN) network, a device-to-device (D2D) communication system, a machine to machine (M2M) communication system, or an IoT communication system or other communication system.
  • PLMN public land mobile network
  • D2D device-to-device
  • M2M machine to machine
  • Figure 8 is a schematic architectural diagram of a communication system provided by an embodiment of the present application.
  • the communication system includes: a first device 801 and a second device 802.
  • the first device 801 is the sending end of the synchronization signal
  • the second device 802 is the receiving end of the synchronization signal.
  • the first device 801 can be the reader/writer 201
  • the second device 802 can be the tag 202.
  • the first device 801 may be the network device 301, and the second device 802 may be the terminal device 302.
  • the specific device form of the first device 801 may 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 may include: a terminal device in an NR system.
  • the first device 801 and the second device 802 may use OFDM technology to transmit data.
  • the data sent by the first device 801 to the second device 802 may be transmitted through OFDM subcarriers.
  • the data sent by the second device 802 to the first device 801 may be transmitted through OFDM subcarriers.
  • the following description takes the interaction between the first device 801 and the second device 802 as an example.
  • the first device 801 generates a synchronization signal and sends the synchronization signal to the second device 802 .
  • the synchronization signal is generated by OFDM.
  • the synchronization signal may include a first signal and/or a second signal.
  • the first signal is used to determine the starting position in the time domain occupied by the data sent by the first device 801 to the second device 802 .
  • the second signal is used to determine the frequency of data sent by the second device 802 to the first device 801 .
  • the second device 802 receives the synchronization signal from the first device 801, and performs time synchronization and/or frequency synchronization according to the synchronization signal.
  • the first device can generate a synchronization signal through OFDM, so that the synchronization signal and the OFDM subcarriers of the data (hereinafter referred to as downlink data) sent by the first device to the second device are orthogonal to each other, Furthermore, when the second device 802 receives the signal, it can completely separate the time domain waveform of the synchronization signal from the time domain waveform of the OFDM subcarrier carrying downlink data to avoid interference.
  • the synchronization method provided by the embodiments of this application
  • the synchronization signal of the low-power communication system can be made to coexist with the subcarriers of the NR system.
  • the communication system 900 may include: access network devices #1 to #2, and terminal devices #1 to #8.
  • the access network device #1 can directly send data to the terminal device #1 ⁇ terminal device #6, and then the access network device #1 can be the first device 801, and the terminal device #1 ⁇ terminal device #6 can be the second device 801.
  • Device 802; access network device #1 can send data to terminal device #7 and/or terminal device #8 through access network device #2, and then access network device #2 can be the first device 801, terminal device #7 Or terminal device #8 may be the second device 802.
  • the access network device #2, the terminal device #7, and the terminal device #8 may form another communication system 910.
  • the access network device #2 can directly send data to the terminal device #7 or the terminal device #8, and then the access network device #2 can be the first device 801, the terminal device #7 or the terminal device # 8 may be a second device 802.
  • terminal device #4 to terminal device #6 may form another communication system 920.
  • terminal device #4 can directly send data to terminal device #5 and/or terminal device #6, and then terminal device #4 can be the first device 801, terminal device #5 or terminal device # 6 may be the second device 802.
  • the first device 801 in the embodiment of the present application may be an access network device or a terminal device
  • the second device 802 may be a terminal device.
  • the physical form of the first device 801 and the second device 802. The following takes the first device 801 as an access network device and the second device 802 as a terminal device as an example to illustrate the hardware structures of the first device 801 and the second device 802.
  • FIG. 10 it is a schematic diagram of the hardware structure of the terminal device 1000 and the access network device 1010 provided by the embodiment of the present application.
  • the terminal device 1000 includes at least one processor 1001 (in Figure 10, one processor 1001 is taken as an example for illustration), at least one memory 1002 (in Figure 10, one memory 1002 is taken as an example for illustration), and At least one transceiver 1003 (in FIG. 10, one transceiver 1003 is taken as an example for illustration).
  • the terminal device 1000 may also include an output device 1004 and an input device 1005.
  • the processor 1001, the memory 1002 and the transceiver 1003 are connected through communication lines.
  • the communication line may include a path to carry information between the above-mentioned components.
  • the processor 1001 can be a general central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more processors used to control the execution of the program of the present application. integrated circuit.
  • the processor 1001 may also include multiple CPUs, and the processor 1001 may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor.
  • a processor here may refer to one or more devices, circuits, or processing cores for processing data (such as computer program instructions).
  • the memory 1002 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (random access memory (RAM)) or other type that can store information and instructions. Dynamic storage device, it can also be electrically erasable programmable read-only memory (EEPROM), read-only optical disk (compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, compact discs, digital versatile discs, or Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or can be used for Any other medium that carries or stores the desired program code in the form of instructions or data structures and capable of being accessed by a computer, without limitation.
  • the memory 1002 may exist independently and be connected to the processor 1001 through a communication line. Memory 1002 may also be integrated with processor 1001.
  • the memory 1002 is used to store computer execution instructions for executing the solution of the present application, and the processor 1001 controls the execution.
  • the processor 1001 is configured to execute computer execution instructions stored in the memory 1002, thereby implementing the synchronization method described in the embodiment of the present application.
  • the computer execution instructions in the embodiments of the present application may also be called application program codes or computer program codes, which are not specifically limited in the embodiments of the present application.
  • the transceiver 1003 can use any transceiver-like device for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), or wireless local area networks (WLAN) wait.
  • Transceiver 1003 includes a transmitter Tx and a receiver Rx.
  • Output device 1004 communicates with processor 1001 and can display information in a variety of ways.
  • the output device 1004 may be a liquid crystal display (LCD), a light emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector. wait.
  • LCD liquid crystal display
  • LED light emitting diode
  • CRT cathode ray tube
  • the input device 1005 communicates with the processor 1001 and can accept user input in a variety of ways.
  • the input device 1005 may be a mouse, a keyboard, a touch screen device, a sensing device, or the like.
  • the network device 1010 includes at least one processor 1011 (in Figure 10, one processor 1011 is taken as an example for illustration), at least one memory 1012 (in Figure 10, one memory 1012 is taken as an example for illustration), At least one transceiver 1013 (in FIG. 10, the example of including one transceiver 1013 is used for illustration) and at least one network interface 1014 (in FIG. 10, the example of including one network interface 1014 is used for illustration).
  • the processor 1011, the memory 1012, the transceiver 1013 and the network interface 1014 are connected through communication lines.
  • the network interface 1014 is used to connect to the core network device through a link (such as the S1 interface), or to connect to the network interfaces of other network devices through a wired or wireless link (such as the X2 interface) (not shown in Figure 10) , the embodiments of this application do not specifically limit this.
  • the relevant description of the processor 1011, the memory 1012 and the transceiver 1013 may refer to the description of the processor 1001, the memory 1002 and the transceiver 1003 in the terminal device 1000, which will not be described again here.
  • the access network device 1010 in the embodiment of the present application may be a device that accesses the core network or a chip that can be used in a device that accesses the core network.
  • the device that accesses the core network can be, for example, a base station in the Long Term Evolution LTE system, a base station in the global system for mobile communication (GSM), a base station in UMTS, a base station in the NR system, or a base station in PLMN.
  • Base stations broadband network gateway (BNG), aggregation switches, non-3GPP (non 3GPP) network equipment, etc.
  • the base station may include various forms of base stations, such as macro base stations, micro base stations (also called small stations), relay stations, access points, etc., which are not specifically limited in the embodiments of this application.
  • the access network device 1010 in the embodiment of this application may support backscatter communication technology.
  • the access network device 1010 in the embodiment of this application may support sending a wake-up signal.
  • the access network device 1010 in the embodiment of the present application may also be called an access device, which is not specifically limited in the embodiment of the present application.
  • the terminal device 1000 in the embodiment of the present application may be a device used to implement wireless communication functions, such as a terminal or a chip that can be used in a terminal, which is not specifically limited in the embodiment of the present application.
  • the terminal can be an LTE system, GSM, UMTS, NR system, user equipment (UE) in the future evolved PLMN, access terminal, terminal unit, terminal station, mobile station, mobile station, remote station, remote Terminal, mobile device, wireless communication equipment, terminal agent or terminal device, etc.
  • the access terminal can be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), with wireless communications Functional handheld devices, computing devices or other processing devices connected to wireless modems, vehicle-mounted devices, wearable devices, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, industrial control (industrial) Wireless terminals in control, wireless terminals in self-driving, wireless terminals in remote medical, wireless terminals in smart grid, wireless terminals in transportation safety Terminals, wireless terminals in smart cities, wireless terminals in smart homes, etc.
  • the terminal device 1000 may be mobile or fixed.
  • the terminal device 1000 in the embodiment of the present application may support backscatter communication technology.
  • the terminal device 1000 in the embodiment of the present application may support receiving a wake-up signal.
  • the terminal device 1000 may also be called a tag, an MTC terminal, or an NR terminal, etc., which is not specifically limited in the embodiment of the present application.
  • a synchronization method provided by an embodiment of the present application includes the following steps:
  • the first device generates a synchronization signal.
  • the synchronization signal is generated by OFDM. That is to say, the time domain waveform of the synchronization signal may be a waveform obtained by superposing multiple 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.
  • the synchronization signal may be generated by conventional OFDM (conventional OFDM).
  • the first device can map the sequence of the synchronization signal to the subcarriers, and then perform an inverse fast fourier transform (IFFT) to generate the OFDM time domain waveform of the synchronization signal.
  • IFFT inverse fast fourier transform
  • the synchronization signal can also be generated by filtered OFDM (filtered-OFDM, F-OFDM).
  • filtered-OFDM filtered-OFDM
  • F-OFDM filtered-OFDM
  • the synchronization signal may also be generated by other OFDM methods, which is not specifically limited in the implementation of the present application.
  • sequence and data may have the same meaning, where “data” may be represented as a “sequence” composed of multiple "0” or “1” symbols/elements, such as the sequence [01010101101 ] can be represented as data to be sent by the first device or the second device.
  • sequence and “data” can be expressed interchangeably. They are explained here uniformly and will not be described again below.
  • the time domain waveform of the synchronization signal is generated by OFDM.
  • the time domain waveform of the synchronization signal is an OFDM waveform.
  • the minimum transmission unit of the synchronization signal or data sent by the first device to the second device is one OFDM symbol.
  • the time domain resource of the synchronization signal may include one OFDM symbol, or the time domain resource of the synchronization signal may include multiple 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 starting position of the synchronization signal and/or the time domain end position of the synchronization signal.
  • the time domain resource for the synchronization signal includes an OFDM symbol diagram.
  • the time domain resource of the synchronization signal includes OFDM symbol #1 within a subframe.
  • the time domain start position of the synchronization signal is the time domain start position of OFDM symbol #1 in the subframe.
  • the time domain end position of the synchronization signal is the time domain end position of OFDM symbol #1 in the subframe.
  • the time of the synchronization signal The length is the time length of OFDM symbol #1 (i.e. 1 OFDM symbol).
  • the time domain resource of the synchronization signal includes a schematic diagram of two OFDM symbols in a subframe.
  • the time domain resources of the synchronization signal include OFDM symbol #1 and OFDM symbol #2.
  • the time domain start position of the synchronization signal is the time domain start position of OFDM symbol #1 in the subframe.
  • the time domain end position of the synchronization signal is the time domain end position of OFDM symbol #2 in the subframe.
  • the time of the synchronization signal The length is the sum of the time length of OFDM symbol #1 and OFDM symbol #2 (that is, 2 OFDM symbols).
  • the synchronization signal is located before the downlink data sent by the first device, so that the second device can determine the time domain starting position of the downlink data.
  • Figure 14 it is a schematic diagram of a time domain resource of a synchronization signal provided by an embodiment of the present application.
  • the synchronization signal can be adjacent to the downlink data. That is to say, after the second device receives the synchronization signal, it can determine the time domain starting position of the downlink data through the synchronization signal.
  • a guard interval may be added before or after the OFDM time domain signal of the synchronization signal.
  • GI can be CP.
  • an OFDM symbol includes two parts: GI and useful signal ( payload).
  • the useful signal is the OFDM symbol after IFFT of the OFDM frequency domain signal.
  • the useful signal in an OFDM symbol is the part used to transmit "sequence" or "data” or "information”.
  • time length of an OFDM symbol is the sum of the time length T GI of GI and the time length T payload of the useful signal.
  • “useful signal” can also be replaced by “data”, “sequence”, “useful data”, “load”, “useful load”, “load”, and “payload”, etc., which are explained here. No further details will be given below.
  • the time length T payload of the useful signal is related to the sampling frequency and number of sampling points of IFFT.
  • the time length T payload of the useful signal can be characterized by the sampling frequency and the number of sampling points.
  • the time length T GI of GI can also be characterized by the sampling frequency and the number of sampling points.
  • the synchronization signal may include a first signal (which may also be called a Delimiter).
  • the first signal is used to determine the starting position in the time domain occupied by the data (downlink data) sent by the first device to the second device. That is to say, the time domain starting position of the downlink data can be determined through the first signal in the synchronization signal.
  • the synchronization signal may include a first signal (which may also be called a Delimiter).
  • the first signal is used to determine the starting position in the time domain occupied by the data (downlink data) sent by the first device to the second device. That is to say, the second device can determine the time domain starting position of the downlink data through the first signal in the synchronization signal.
  • the downlink data may include a preamble and a wake-up signal.
  • the preamble can be a sequence consisting of "0" and "1".
  • the wake-up signal may be used to indicate the identity of the second device.
  • the wake-up signal may be used to indicate the identity of the terminal device group in which the second device is located.
  • the wake-up signal may be used to indicate part of the identity of the second device.
  • the wake-up signal may be used to indicate the identity of the terminal device group in which the second device is located.
  • the first signal can be used to wake up the second device. That is to say, after the second device receives the first signal from the first device, the counter of the second device starts to work and starts to detect the time length of the received signal to receive and demodulate the downlink data. In other words, before the second device receives the first signal, the counter of the second device does not work and may not detect the time length of the received signal, so as to achieve the effect of energy saving.
  • the first device Before the synchronization signal, the first device sends a carrier signal.
  • the carrier signal is used to provide energy to the second device, that is, the carrier signal is a high-level signal. Accordingly, the first signal may be a low level signal. That is to say, when the second device receives the low-level first signal after the carrier signal, it can determine to start receiving downlink data.
  • 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 of data sent by the second device to the first device.
  • the frequency of data sent by the second device to the first device may be BLF; further, the second device may determine the BLF using formula (1).
  • the functions that can be realized by the first signal may include the functions realized by the delimiter in the preamble part of the frame header
  • the functions that can be realized by the second signal may include the functions realized by the TRcal in the preamble part of the frame header. Functions implemented.
  • the synchronization signal only includes the first signal.
  • the time domain resource of the synchronization signal includes one or more OFDM symbols. Therefore, when the synchronization signal only includes the first signal, the time length of the first signal may be the time length of one or more OFDM symbols.
  • the scenario where the synchronization signal only includes the first signal may be: the first device sends downlink signaling other than the query command to the second device. At this time, since the downlink signaling other than the query command does not include the DR, the second device does not need to calculate the BLF, and the synchronization signal may only include the first signal. Alternatively, where the second device has determined the BLF, the synchronization signal may only include the first signal.
  • the synchronization signal includes a first signal and filling data. That is to say, 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 synchronization signal can be made by filling data.
  • the time length is the time length of one or more OFDM symbols.
  • the filling data can be invalid data or useless data.
  • the synchronization signal includes a first signal and a second signal. That is to say, the second device can determine the time domain starting position and BLF of the downlink data based on the synchronization signal.
  • the scenario where the synchronization signal includes the first signal and the second signal may be: the downlink signaling sent by the first device is a query command, where the query command carries the DR.
  • the second device can determine the time domain starting position of the downlink data based on the first signal, and then obtain the second signal and the DR in the query command, and then the second device can determine the DR based on the time length of the second signal, and Formula (1), calculate BLF.
  • the first device sends a synchronization signal to the second device. Accordingly, the second device receives the synchronization signal from the first device.
  • the second device performs time synchronization and/or frequency synchronization according to the synchronization signal.
  • the second device can determine the starting position of the time domain occupied by the downlink data according to the first signal in the synchronization signal, and determine the BLF according to the second signal in the synchronization signal.
  • the synchronization signal is generated by OFDM
  • the synchronization signal and the OFDM subcarriers transmitting downlink data are orthogonal to each other, and then the second device can demodulate the time domain waveform of the synchronization signal when demodulating the signal. It is completely separated from the time domain waveform of OFDM subcarriers transmitting downlink data to avoid interference. Therefore, when the NR system introduces low-power communication systems such as Passive IoT or ambient power-enabled IoT, the synchronization signals of the low-power communication system can coexist with the subcarriers of the NR system.
  • the actions of the first device in the above steps S1101 to S1103 can be performed by the processor 1011 in the access network device 1010 shown in Figure 10 Call the application program code stored in the memory 1012 to instruct the access network device to execute; in the case where the first device is a terminal device, the actions of the first device in the above steps S1101 to S1103 can be performed by the terminal device shown in Figure 10
  • the processor 1001 in the processor 1000 calls the application program code stored in the memory 1002 to instruct the terminal device to execute, and this embodiment does not impose any restrictions on this.
  • the actions of the second device in the above steps S1101 to S1103 can be called by the processor 1001 in the terminal device 1000 shown in Figure 10 in the memory 1002
  • the stored application code is used to instruct the terminal device to execute, and this embodiment does not impose any restrictions on this.
  • the second signal is located after the first signal. That is to say, after the second device detects the first signal, the second device can detect the second signal, obtain the time length of the second signal, and then combine it with the DR carried in the downlink data to calculate the BLF.
  • the first signal and the second signal are located in different OFDM symbols.
  • the time interval between the OFDM symbols occupied by the first signal and the OFDM symbols occupied by the second signal is predefined. That is to say, after the second device detects the first signal, it can determine the OFDM symbols occupied by the second signal.
  • the time interval between the OFDM symbols occupied by the first signal and the OFDM symbols occupied by the second signal can be negotiated in advance by the first device and the second device; or, the first signal occupied by the second device can be configured in advance.
  • the first signal and the second signal are located in two adjacent OFDM symbol Inside. That is to say, after the second device detects the first signal, it can determine that the OFDM symbol following the first signal carries the second signal.
  • the OFDM symbols occupied by the first signal and the OFDM symbols occupied by the second signal are The occupied OFDM symbols are separated by T OFDM symbols. That is to say, after the second device detects the first signal, it can start receiving the second signal after T OFDM symbols.
  • the first signal and the second signal are located in the same OFDM symbol. That is to say, after the second device detects the first signal, it can determine to start receiving the second signal.
  • FIG. 18 illustrates a schematic structural diagram 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 first signal may be less than the time length of one OFDM symbol.
  • the application examples do not specifically limit this.
  • the above synchronization signal may also include other symbols, such as data 0 in the preamble part, RTcal, etc.
  • the time interval between the first signal and the second signal is predefined. That is to say, after the second device detects the first signal, it can determine the time domain starting position of the second signal.
  • time interval between the first signal and the second signal can be negotiated in advance between the first device and the second device; or the time interval between the first signal and the second signal is configured in advance on the second device; or the protocol The time interval between the first signal and the second signal is agreed upon, which is not specifically limited in the embodiment of the present application.
  • step S1101 is explained in detail.
  • the waveform of the synchronization signal can be an orthogonal frequency division multiplexing waveform using a cyclic prefix (conventional OFDM using a Cyclic Prefix, CP-OFDM). That is to say, the OFDM symbol occupied by the synchronization signal includes two parts: CP and useful signal. Furthermore, the time length of an OFDM symbol is the sum of the time length T CP of the CP and the time length T payload of the useful signal.
  • CP-OFDM Cyclic Prefix
  • the time length T CP of CP satisfies in It can be obtained by formula (2).
  • Z can be used to represent the time length T payload of the useful signal.
  • the access network device #1 can directly send a signal to the terminal device # 1 to terminal device #6 send data, so access network device #1 can be the first device, and terminal device #1 to terminal device #6 can be the second device.
  • the synchronization signal sent by the first device is a signal transmitted in the downlink in the NR system
  • the waveform of the downlink transmission in the NR system is a CP-OFDM waveform.
  • the waveform of the synchronization signal may be an orthogonal frequency division multiplexing waveform using a cyclic prefix (The downlink transmission waveform is conventional OFDM using a Cyclic Prefix).
  • the waveform of the synchronization signal is generated by CP-OFDM based on the first sequence.
  • the first sequence may be a predefined sequence.
  • the first sequence may include multiple elements.
  • each element can be represented by the binary symbol "0" or "1".
  • the first sequence may be composed of k constellation points.
  • the constellation points can be ASK constellation points, phase-shift keying (PSK) constellation points, and quadrature amplitude modulation (quadrature amplitude modulation, QAM) constellation points.
  • PSK phase-shift keying
  • QAM quadrature amplitude modulation
  • the modulation orders of ASK, PSK, and QAM are not specifically limited in the embodiment of this application.
  • the first sequence may be stored or configured in advance on the first device; or the protocol stipulates the first sequence, which is not specifically limited in the embodiments of this application.
  • the synchronization signal can be generated by performing subcarrier mapping on the first sequence, mapping the first sequence to subcarriers, and then performing IFFT and adding CP to generate the waveform of the synchronization signal.
  • CP can be added before the useful signal.
  • the waveform of the synchronization signal is a CP-OFDM waveform and is generated by (discrete fourier transform, DFT) transform precoding. That is to say, compared with the first method, the second method adds a DFT operation to realize the conversion from the time domain to the frequency domain. Furthermore, the synchronization signal sent by the first device is a time domain signal, which can avoid the problem of higher peak to average power ratio (PAPR) caused by sending frequency domain OFDM signals.
  • PAPR peak to average power ratio
  • the waveform of the synchronization signal is a CP-OFDM waveform, and is generated by DFT spreading transform precoding.
  • the waveform of the synchronization signal is a CP-OFDM waveform, and the waveform of the synchronization signal has a transform precoding function that performs DFT spreading.
  • the OFDM method corresponding to the second method can also be called discrete fourier transform-spread OFDM, DFT-S-OFDM.
  • the terminal device #4 can directly send a signal to the terminal device #5 and/or the terminal.
  • Device #6 sends data, so terminal device #4 can be the first device, and terminal device #5 or terminal device #6 can be the second device.
  • the communication link through which the terminal device sends data may be an uplink in the NR system. Therefore, the waveform of the synchronization signal sent by the first device may be the waveform of uplink transmission in the NR system, and the waveform of uplink transmission in the NR system is the DFT-S-OFDM waveform.
  • the waveform of the synchronization signal adopts the DFT-S-OFDM waveform (The downlink transmission waveform is conventional OFDM using a CP with a transform precoding function performing DFT spreading).
  • the waveform of the synchronization signal is generated by DFT transform precoding, including: the waveform of the synchronization signal is the waveform obtained after the second sequence is subjected to CP-OFDM.
  • the second sequence is a sequence obtained by performing DFT spread spectrum transform precoding on the first sequence.
  • the synchronization signal can be obtained by performing DFT on the first sequence to obtain the second sequence, performing subcarrier mapping on the second sequence, and then performing IFFT and adding CP to generate the waveform of the synchronization signal.
  • the time domain position and time length of the first signal will be further elaborated below.
  • the time domain resource of the first signal includes the first K time units among the N time units corresponding to the useful signal in one OFDM symbol, and K is a positive integer. That is to say, the time domain resource of the first signal includes the starting part of the useful signal in the OFDM symbol, and the second device can first detect the first signal before the second signal and downlink data, so as to facilitate subsequent downlink data or the second Signal reception. Moreover, when K is less than N, the first signal only occupies part of the time domain resources of the OFDM symbol, so the idle time domain resources in the OFDM symbol can be used to transmit other content, such as the second signal, data 0, or RTcal, etc. The utilization of time domain resources of OFDM symbols can be improved.
  • FIG 21 it is a schematic diagram of time domain resources of the first signal provided by this embodiment of the present application.
  • the time length of the useful signal is N time units
  • the time domain resource of the first signal includes the first K time units among the N time units. That is to say, 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 greater than or equal to K time units.
  • K can be equal to N.
  • the time domain resource of the first signal may include time domain units corresponding to a positive integer number of OFDM symbols.
  • the positive integer number of OFDM symbols is used to carry the first signal.
  • the time domain unit corresponding to the OFDM symbol may refer to the time length of one OFDM symbol.
  • the time unit may be a constant ⁇ , or a time unit T c , or a time unit T s , or a preset sampling point of IFFT, or a preset sampling frequency of IFFT, or a subcarrier interval, etc. .
  • preset sampling point in IFFT has the same meaning as “sampling point in IFFT”.
  • preset sampling points in IFFT and “sampling points in IFFT” can be interchangeably expressed. They are explained uniformly here and will not be described again below.
  • the time length of the first signal will be further explained below in combination with the time domain waveform of the signal.
  • the second device before receiving the first signal from the first device, the second device may detect the time length of the received signal. That is to say, the second device can determine whether the received signal is the first signal by detecting the time length of the received signal and comparing it with the time length of the first signal.
  • the first signal is a low-level signal. That is to say, if the second device detects a low-level signal that is greater than or equal to the time length of the first signal, it can be determined that the first signal is detected.
  • the amplitude of the time domain waveform corresponding to the first signal is less than the third threshold.
  • the absolute value of the amplitude of the time domain waveform corresponding to the first signal is less than the fourth threshold.
  • the maximum value of the amplitude of the time domain waveform corresponding to the first signal is less than the fifth threshold.
  • the average value of the amplitude of the time domain waveform corresponding to the first signal is less than the sixth threshold.
  • the second device can calculate the average value of the amplitude of the time domain waveform of the received signal. That is, if the average value is less than the sixth threshold, the second device determines that the received signal is the first signal.
  • the third to sixth thresholds may be predefined.
  • the third threshold to the sixth threshold may be equal or unequal. Taking the third threshold and the fifth threshold as an example, the third threshold may be less than the fifth threshold, or the third threshold may be equal to the fifth threshold, or the third threshold may be greater than the fifth threshold.
  • the embodiments of the present application do not specifically limit the values of the third threshold to the sixth threshold.
  • the scenario where the first signal is low level may be the scenario where the first device provides energy to the second device through a carrier signal as shown in FIG. 16 . It can be understood that since the carrier signal supplies energy to the second device, the carrier signal is a high-level signal. In this way, when the second device receives the low-level first signal, the second device The device can determine to start receiving downlink data.
  • the time domain resource of the first signal also includes a partial time unit corresponding to the CP in the OFDM symbol in which the first signal is located.
  • the level of the CP signal is the same as the level of the first signal. That is to say, when the first signal is low level, by adding part of the time unit corresponding to the CP in the time domain resource of the first signal, the duration of the low level signal is long enough, and the first signal can be combined with Distinguish between the low level part of the second signal and/or the low level part of the downlink data. In this way, when the second device receives the signal, it can determine that the low-level signal with the longest duration in the received signal is the first signal.
  • the second device determines that the first signal is detected using the schematic structural diagram of the downlink signal shown in Figure 22.
  • the time length of the first signal is greater than the time length of the low level part in the downlink data, and is greater than the time length of the low level part of the second signal.
  • the second device receives the downlink signal, it can determine that the low-level signal with the longest duration is the first signal.
  • the number of consecutive 0 symbols (low levels) in the third sequence used to generate the second signal in the first sequence is smaller than the number of consecutive 0 symbols (low levels) used in the first sequence.
  • the number of consecutive 0 symbols (low level) in the fourth sequence that generates the first signal is smaller than the number of consecutive 0 symbols (low levels) used in the first sequence.
  • the first sequence takes the first sequence as [000111100110].
  • the first three elements in the first sequence are the fourth sequence [000]
  • the third sequence can be the part [111100110] of the first sequence excluding [000].
  • the number of consecutive 0 symbols in the third sequence (2) is smaller than the number of consecutive 0 symbols (3) in the fourth sequence.
  • an OFDM CP can be obtained by copying the signal carried on the last S1 time units among the N time units corresponding to the useful signal in an OFDM symbol.
  • the time length of the last S1 time units is equal to the time length of the CP in the OFDM symbol.
  • the signals carried in the last S time units among the N time units corresponding to the useful signal in the OFDM symbol where the first signal is located are low-level signals.
  • the time length of the last S time units is greater than or equal to the time length of the CP in the OFDM symbol where the first signal is located. That is to say, the signal carried in the last S time units corresponding to the useful signal in the OFDM symbol where the first signal is located is a low-level signal, which can ensure that the level of the CP signal is low-level. In this way, the duration of the low level part of the first signal can be increased.
  • the last element of the first sequence is 0.
  • the first sequence ends with 0.
  • the first sequence is [000111100110]
  • the last element of the sequence is 0.
  • 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 useful signal in the OFDM symbol in which the first signal is located is less than the third threshold.
  • 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 useful signal in the OFDM symbol in which the first signal is located is less than the fourth threshold.
  • 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 useful signal in the OFDM symbol in which the first signal is located is less than the fifth threshold.
  • the average amplitude of the time domain waveform of the signal carried in the last S time units among the N time units corresponding to the useful signal in the OFDM symbol in which the first signal is located is less than the sixth threshold.
  • the third to sixth thresholds may be less than or equal to the average value of the amplitude of the useful signal in the OFDM symbol where the first signal is located.
  • the waveform of the synchronization signal is based on the first sequence and generated by CP-OFDM
  • the first sequence includes Q elements, and the last P elements among the Q elements are the first symbols representing low levels.
  • the first symbol may be the symbol 0.
  • the time length of the first signal will be further described below in conjunction with the angle at which the second device detects the first signal.
  • the time length of the first signal is predefined. That is to say, for the second device, the time length of the first signal is known. If the second device detects a low-level signal within the known time length, it can be determined that the first signal is detected. This can improve the efficiency of the second device in detecting the first signal and/or reduce the complexity of the second device in detecting the first signal.
  • time length of the first signal may be stored or configured in advance on the second device; or the time length of the first signal is stipulated in the protocol, which is not specifically limited in the embodiment of the present application.
  • the time length of the first signal may vary with different time domain resources where the first signal is located.
  • the time length of the first signal may vary depending on the time domain resource for sending the first signal.
  • the value of the time length T payload of the useful signal is Z
  • the value of T payload is also equal to the above N time units, where Z is represented by the constant ⁇ and the subcarrier spacing configuration ⁇ , that is, in the subcarrier
  • the Z value is different. Therefore, the value of the time unit changes with the different subcarrier spacing configurations, and then the time length of the K time units also changes with the different subcarrier spacing configurations.
  • the time length (including K time units) of the first signal is different. The larger the value configured in the subcarrier spacing is, the smaller the value of the time unit is, and thus the shorter the time length of the K time units in the first signal is.
  • the time domain resource of the first signal includes the CP of the OFDM symbol where the first signal is located, even if the subcarrier spacing configuration is the same, the time length of the first signal may be different.
  • the CP types may be different. For example, when the subcarrier spacing configuration ⁇ is 2, the subcarrier spacing ⁇ f is 60kHz, and the CP is normal CP or extended CP. You can determine through signaling configuration that when ⁇ is 2, use normal CP or extended CP. The length of time corresponding to normal CP is different from the length of time corresponding to extended CP.
  • the length of CP corresponding to different OFDM symbols may be different.
  • Figure 23 it is a schematic diagram of the time length of each OFDM symbol in a time slot of the NR system provided by the embodiment of the present application. Among them, as described in formula (2), for normal CP, the time length of the CP of OFDM symbol #0 and the time length of the CP of OFDM symbol #7 are greater than the time length of the CP of other numbered OFDM symbols.
  • the time domain resource of the first signal includes the CP of the OFDM symbol where the first signal is located, even if the subcarrier configuration is the same, the time length of the first signal changes with different CP types. In other words, the time length of the first signal varies with the position of the OFDM symbol.
  • the CP of OFDM symbol #0 and the CP of OFDM symbol #7 are expressed as "long CP (long CP)", and the CP of other numbered OFDM symbols are expressed as " Short CP (short CP)”.
  • the time length of the CP of the OFDM symbol in which the first signal is located is fixed. That is to say, under the same subcarrier spacing configuration, the second device does not need blind detection when receiving the first signal.
  • the first signal with the same time length can improve the efficiency of the second device in detecting the first signal and/or reduce the complexity of the second device in detecting the first signal.
  • the OFDM symbol in which the first signal is located is an OFDM symbol including a short CP in the normal CP. That is to say, the time length of the CP of the OFDM symbol where the first signal is located is 144 ⁇ 2 - ⁇ ⁇ T c in formula (2). Furthermore, under the same subcarrier spacing configuration, the time length of the first signal is a fixed value.
  • the number of the OFDM symbol where the first signal is located satisfies l ⁇ 0 or l ⁇ 7 ⁇ 2 ⁇ . That is to say, the time length of the CP of the OFDM symbol where the first signal is located is 144 ⁇ 2 - ⁇ ⁇ T c in formula (2).
  • the OFDM symbol in which the first signal is located is an OFDM symbol including a long CP in the normal CP. That is to say, the time length of the CP of the OFDM symbol where the first signal is located is (144 ⁇ 2 - ⁇ +16 ⁇ ) ⁇ T c in formula (2). Furthermore, under the same subcarrier spacing configuration, the time length of the first signal is a fixed value.
  • the OFDM symbol in which the first signal is located is an OFDM symbol including extend CP. That is to say, the time length of the CP of the OFDM symbol where the first signal is located is 512 ⁇ 2 - ⁇ ⁇ T c in formula (2). Furthermore, under the same subcarrier spacing configuration, the time length of the first signal is a fixed value.
  • the subcarrier spacing of the first signal is 60 kHz.
  • the subcarrier spacing ⁇ of the first signal is configured to be 2. That is to say, the time length of the CP of the OFDM symbol where the first signal is located is 512 ⁇ 2 - ⁇ ⁇ T c in formula (2).
  • the time length of the first signal will be further described below from the perspective of time domain resource utilization of the first device sending the first signal.
  • the time length of the first signal is greater than or equal to the first threshold and less than or equal to the second threshold.
  • the first threshold is greater than or equal to T LCP +t ⁇ Z
  • T LCP is the time length of the long CP
  • Z is the time length of the useful signal T payload
  • t is the coefficient
  • the second threshold is less than or equal to T SCP +t ⁇ Z
  • T SCP is the time length of short CP. That is to say, the time length of the first signal can vary within a small range, and the first device can send the first signal at any time domain position. In other words, the first device does not need to send the first signal on a specific time domain resource, which can improve the utilization of time domain resources.
  • t can take a value of 1, 1/2, 1/4, or 1/5, etc., which is not specifically limited in the embodiment of the present application.
  • the first threshold and the second threshold are explained in conjunction with the NR system parameters in the preamble.
  • the first threshold is X+Y
  • the second threshold is XY
  • X t ⁇ Z+(T LCP +T SCP )/2
  • TLCP (144 ⁇ 2 - ⁇ +16 ⁇ ) ⁇ Tc
  • TSCP 144 ⁇ 2 - ⁇ ⁇ Tc . Substituting these parameters into X and Y , we can get c .
  • the second device detects a low level within the time range of [XY, X+Y] signal, the second device determines that the first signal is detected.
  • time domain resources of the second signal in the embodiment of the present application will be further described below in conjunction with the OFDM method for generating synchronization signals.
  • the time domain resource of the second signal includes M time units among the N time units corresponding to the useful signal in one OFDM symbol, where M is a positive integer. Since IFFT is required in the process of generating OFDM symbols, and IFFT sampling is an integer, if M among the M time units included in the time domain resource of the second signal is not a positive integer, then after IFFT, the non-integer part will be Quantized to integers, thus introducing errors. That is to say, in the process of generating the second signal through OFDM, M is a positive integer, which can reduce the error introduced by quantization at the IFFT preset sampling rate.
  • FIG 25 it is a schematic diagram of time domain resources of the second signal provided by this embodiment of the present application.
  • the time length of the useful signal is N time units
  • the time domain resource of the second signal includes M time units among the N time units.
  • M time units are M consecutive time units.
  • the time unit may be a constant ⁇ , or a time unit T c , or a time unit T s , or a preset sampling point of IFFT, or a preset sampling frequency of IFFT, or a subcarrier interval. wait.
  • the synchronization signal includes a second signal.
  • the waveform of the synchronization signal is generated through CP-OFDM after performing DFT transform precoding on the first sequence.
  • the first sequence includes the third sequence.
  • the third sequence is a sequence used to generate the second signal.
  • M satisfies the first condition, which includes:
  • N is L times M, and the number of elements contained in the first sequence is L times the number of elements contained in the third sequence, where N is a power of 2 and L is a positive integer.
  • the time domain resources of the second signal will be described below with reference to the schematic diagram of the time domain resources of the downlink signal shown in FIG. 26 .
  • the downlink signal includes carrier signal, synchronization signal and downlink data.
  • a carrier signal is sent in OFDM symbol #0 before the synchronization signal.
  • the carrier signal is used to provide energy for the second device, and the carrier signal is high level.
  • OFDM symbol #1 after the carrier signal carries the synchronization signal
  • OFDM symbol #2 after the synchronization signal carries downlink data.
  • the synchronization signal includes a first signal and a second signal, the sub-carrier spacing of the synchronization signal is 15 kHz, and the time length of the first signal is 21.6 ⁇ s +/-2%, that is, the tolerance range is 2%.
  • the synchronization signal can be sent in any OFDM symbol.
  • the time domain resource configuration of the synchronization signal is flexible and the utilization rate is high.
  • the sampling rate is 1.92MHz
  • the number of sampling points of one OFDM symbol is 128, that is, the useful signal of one OFDM symbol corresponds to 128 time units.
  • the first sequence can be [000111100110], and the number of elements of 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.
  • time unit and “number of sample points” after OFDM can be replaced Change the expression and explain it uniformly here, and will not go into details below.
  • the time length of the second signal will be further described below in conjunction with the way in which the second device measures the time length of the signal.
  • the second device measures the time length of the second signal through a counter.
  • the counting error range of the counter is +/-1 clock cycle.
  • FIG. 27 it is a schematic diagram of the second device measuring the time length of the high level part through a counter.
  • the time length of signal 1 is 3 clock cycles, and the boundary of signal 1 and the clock boundary are aligned, so signal 1 can be accurately counted as 3 clock cycles.
  • the time length of signal 2 is 2.5 clock cycles. The boundary of signal 2 and the clock boundary are not aligned.
  • the counter can only count integers, so signal 2 is counted as 3 clock cycles, which introduces errors.
  • error represents the error
  • M 1 represents the measurement count of the second device's measurement of the signal time length
  • M 2 represents the real count of the actual clock cycle of the real clock of the signal time length.
  • M 2 is proportional to M.
  • M is the maximum value among multiple values that satisfy the first condition. That is to say, the larger the value of M, the smaller the error of the second device in measuring the time length of the second signal.
  • the synchronization signal includes the first signal.
  • the first sequence for generating the synchronization signal may be [000000000000].
  • the first sequence to generate the synchronization signal may be [000110].
  • the first sequence to generate the synchronization signal may be [001100].
  • the waveform of the synchronization signal is generated by CP-OFDM after 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 wake up the second device. That is to say, after the second device receives the first signal from the first device, the counter of the second device starts to work and starts to detect the time length of the received signal to receive and demodulate the downlink data. In other words, before the second device receives the first signal, the counter of the second device does not work and may not detect the time length of the received signal, so as to achieve the effect of energy saving.
  • the synchronization signal may include a first signal and a second signal.
  • the first sequence to generate the synchronization signal may be [0000000000001111001111100].
  • the first signal may correspond to [000000000000] in the first sequence
  • the second signal may correspond to [111100] in the first sequence.
  • the second signal may be [111100] corresponding to the end position in the first sequence; or the second signal may also correspond to [111100] which is not at the end position in the first sequence.
  • the first sequence may be [000000000000111111111100].
  • the first signal corresponds to [000000000000] in the first sequence
  • the second signal corresponds to [111111111100] in the first sequence.
  • the first sequence to generate 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.
  • the first sequence may be [001100111100].
  • the first signal corresponds to the first sequence [001100]
  • the second signal corresponds to [111100] in the first sequence.
  • the waveform of the synchronization signal is generated by CP-OFDM after 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 wake up the second device. That is to say, after the second device receives the first signal from the first device, the counter of the second device starts to work and starts to detect the time length of the received signal to receive and demodulate the downlink data. In other words, before the second device receives the first signal, the counter of the second device does not work and may not detect the time length of the received signal, so as to achieve the effect of energy saving.
  • the antenna port through which the first device sends the first signal is the same as the antenna port through which the second signal is sent.
  • the antenna port through which the second device receives the first signal is the same as the antenna port through which the second signal is received.
  • 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.
  • the CP type of the OFDM symbol in which the first signal is located is the same as the CP type of the OFDM symbol in which the second signal is located.
  • 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 CP; or, the CP type of the OFDM symbol where the first signal is located and the OFDM symbol where the second signal is located are extended CP.
  • the CP types are all normal CP.
  • the subcarrier spacing of the first signal is the same as the subcarrier spacing of the second signal.
  • the synchronization method provided by the embodiment of the present application may also include the following steps:
  • the second device sends capability information to the first device. Accordingly, the first device receives capability information from the second device. That is to say, the second device can report capability information to the first device.
  • the capability information may include one or more of the following: whether the second device supports energy harvesting, whether the second device supports envelope detection, or whether the second device supports backscatter communication.
  • the second device supporting energy collection may mean that the second device supports autonomously acquiring other types of energy (such as solar energy, temperature difference thermal energy, vibration energy, wind energy, or radio frequency energy, etc.) from the environment and converting it into for electrical energy.
  • the benefit of energy collection is to replace the battery to power the device or supplement the battery energy, thereby extending the service life of the device.
  • the energy generated through energy collection can be provided to the signal processing or data storage circuit of the second device to maintain the normal operation of the second device. working status.
  • the second device supporting envelope detection may mean that the second device supports receiving signals in a manner of envelope detection.
  • the signal may be a signal from the first device.
  • envelope detection can refer to a signal detection method that obtains the envelope or amplitude line of the low-frequency original signal after half-wave or full-wave rectification of a high-frequency or intermediate-frequency input signal.
  • the second device can obtain the envelope of the original signal after receiving the signal in a manner including detection.
  • the second device can digitally sample the envelope of the original signal and compare it with the amplitude or energy threshold set by the second device to determine whether the received signal is 1 or 0.
  • the second device can also determine whether the received signal is 1 or 0 based on other implementation methods, which is not specifically limited in this embodiment of the present application.
  • the second device supporting backscatter communication may mean that the second device supports radio transmission without active transmission.
  • the second device can transmit information to the first device if it has a radio frequency link; or, the second device supports transmitting information to the first device if it has a radio frequency link that actively transmits but does not need to be turned on. That is to say, the second device mainly relies on an excitation device other than the first device or a continuous carrier wave transmitted by the first device for modulation.
  • the second device can reflect part or all of the incident carrier waves by adjusting the impedance of the antenna of the second device; or the second device can also adjust the impedance of the antenna of the second device so as not to reflect the incident carrier waves; or Absorbs the energy of the incident carrier wave. In this way, by adjusting the impedance of the antenna of the second device, the second device can modulate the digital information of the second device onto the incident carrier wave and transmit it to the first device.
  • the maximum bandwidth supported by the second device is limited.
  • the maximum uplink bandwidth supported by the second device does not exceed X1.
  • X1 is 20MHz, or X1 is 5MHz, or X1 is 3MHz, or X1 is 1.4MHz, or X1 is 1MHz, or X1 is 720kHz, or X1 is 540kHz, or X1 is 360kHz, or X1 is 180kHz.
  • X1 is K1 resource blocks, and K1 is a positive integer.
  • K1 is a positive integer less than or equal to 11, or K1 is a positive integer less than or equal to 25, or K1 is a positive integer less than or equal to 51, or K1 is a positive integer less than or equal to 106.
  • the maximum downlink bandwidth supported by the second device does not exceed Y1.
  • Y1 is 20MHz, or Y1 is 5MHz, or Y1 is 3MHz, or Y1 is 1.4MHz, or Y1 is 1MHz, or Y1 is 720kHz, or Y1 is 540kHz, or Y1 is 360kHz, or Y1 is 180kHz.
  • Y1 is K2 resource blocks, and K2 is a positive integer.
  • K2 is a positive integer less than or equal to 11, or K2 is a positive integer less than or equal to 25, or K2 is a positive integer less than or equal to 51, or K2 is a positive integer less than or equal to 106.
  • the maximum uplink bandwidth supported by the second device is less than or equal to the maximum downlink bandwidth supported by the second device.
  • the second device supports a limited number of transmitting and/or receiving antennas.
  • the number of receiving antennas of the second device does not exceed X2.
  • X2 is 1, or 2, or 4.
  • the number of receiving branches (Rx branches) of the second device does not exceed X2, where X2 is 1, or 2, or 4.
  • the number of transmitting antennas of the second device does not exceed Y2.
  • Y2 is 1, or 2, or 4.
  • the number of sending branches of the second device does not exceed Y2.
  • Y2 is 1, or 2, or 4.
  • the number of transmitting antennas of the second device is greater than or equal to the number of receiving antennas of the second device.
  • the number of sending branches of the second device is greater than or equal to the number of receiving branches of the second device.
  • the "receiving branch” may also be called “the number of received radio frequency channels” or “the number of received radio frequency chains (RF chains)”.
  • “Sending branches” can also be called “number of RF channels sent”, or “number of RF chains sent”.
  • the second device may not transmit and receive at the same time on the serving cell with the paired spectrum.
  • the methods and/or steps implemented by the first device can also be implemented by components that can be used in the first device (such as processors, chips, chip systems, circuits, logic modules, or software) accomplish.
  • the methods and/or steps implemented by the second device may also be implemented by components (such as processors, chips, chip systems, circuits, logic modules, or software) available for the second device.
  • the above mainly introduces the solutions provided by this application.
  • this application also provides a communication device, which is used to implement various methods in the above method embodiments.
  • the communication device may be the first device in the above method embodiment, or a device including the first device, or a component that can be used in the first device, such as a chip or a chip system.
  • the communication device may be the second device in the above method embodiment, or a device including the second device, or a component that can be used in the second device, such as a chip or a chip system.
  • the communication device includes corresponding hardware structures and/or software modules for performing each function.
  • the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is performed by hardware or computer software driving the hardware depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each specific application, but such implementations should not be considered beyond the scope of this application.
  • Embodiments of the present application can divide the communication device into functional modules according to the above method embodiments.
  • functional modules can be divided into corresponding functional modules, or two or more functions can be integrated into one processing module.
  • the above integrated modules can be implemented in the form of hardware or software function modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical function division. In actual implementation, there may be other division methods.
  • FIG. 28 shows a schematic structural diagram of the first device 280.
  • the first device 280 includes a processing module 2801 and a transceiver module 2802.
  • the first device 280 may also include a storage module (not shown in Figure 28) for storing program instructions and data.
  • the processing module 2801 is used to generate a synchronization signal.
  • the transceiver module 2802 is used to send synchronization signals to the second device.
  • the synchronization signal is generated by OFDM, and the synchronization signal includes a first signal and/or a second signal.
  • the first signal is used to determine the starting position of the time domain occupied by the data sent by the first device to the second device,
  • the second signal is used to determine the frequency of data sent by the second device to the first device.
  • the synchronization signal includes a first signal and a second signal, wherein the second signal is located after the first signal.
  • the first signal and the second signal are located within the same OFDM symbol.
  • the waveform of the synchronization signal is a CP-OFDM waveform.
  • the waveform of the synchronization signal is generated by CP-OFDM based on the first sequence.
  • the waveform of the synchronization signal is generated by DFT transform precoding.
  • the waveform of the synchronization signal is generated by DFT transform precoding, including: the waveform of the synchronization signal is the waveform obtained after the second sequence is subjected to CP-OFDM, wherein the second sequence is the first sequence.
  • the sequence obtained after DFT transform precoding is the waveform obtained after DFT transform precoding.
  • the time domain resource of the first signal includes the first K time units among the N time units corresponding to the useful signal in one OFDM symbol, where K is a positive integer, where the useful signal in one OFDM symbol is The part of OFDM symbols that carries useful information or useful data.
  • the time domain resource of the first signal also includes a partial time unit corresponding to the CP in the OFDM symbol in which the first signal is located.
  • the signals carried on the last S time units among the N time units corresponding to the useful signal in the OFDM symbol where the first signal is located are low-level signals, where the time length of the last S time units is greater than Or equal to the time length of the CP in the OFDM symbol where the first signal is located, where the useful signal in an OFDM symbol is the part of an OFDM symbol that carries useful information or useful data.
  • the time domain resource of the second signal includes M time units among the N time units corresponding to the useful signal in one OFDM symbol, where M is a positive integer, where the useful signal in one OFDM symbol is one OFDM symbol.
  • M is a positive integer
  • the useful signal in one OFDM symbol is one OFDM symbol.
  • the synchronization signal includes a second signal, wherein the waveform of the synchronization signal is generated by CP-OFDM after performing DFT transform precoding on the first sequence, and the first sequence includes a third sequence, and the third The sequence is the sequence used to generate the second signal; M satisfies the first condition, which includes:
  • N is L times M, and the number of elements contained in the first sequence is L times the number of elements contained in the third sequence, where N is a power of 2 and L is a positive integer.
  • M is the maximum value among multiple values that satisfy the first condition.
  • the transceiving module 2802 is also used to receive capability information from the second device.
  • the capability information includes at least one of the following: whether the second device supports energy harvesting, whether the second device supports envelope detection, or whether the second device supports backscatter communication.
  • the first device 280 is presented in the form of dividing various functional modules in an integrated manner.
  • a “module” here may refer to a specific application specific integrated circuit (ASIC), a circuit, a processor and memory that executes one or more software or firmware programs, an integrated logic circuit, and/or other devices that can provide the above functions.
  • ASIC application specific integrated circuit
  • the first device 280 when the first device 280 is an access network device, in terms of hardware implementation, those skilled in the art can imagine that the first device 280 may take the form of the access network device 1010 shown in FIG. 10 .
  • the function/implementation process of the processing module 2801 in Figure 28 can be implemented by the processor 1011 in the access network device 1010 shown in Figure 10 calling the computer execution instructions stored in the memory 1012.
  • the function/implementation process of the transceiver module 2802 in Figure 28 can be implemented by the transceiver 1013 in the access network device 1010 shown in Figure 10 .
  • the first device 280 when the first device 280 is a terminal device, in terms of hardware implementation, those skilled in the art can imagine that the first device 280 may take the form of the terminal device 1000 shown in FIG. 10 .
  • the function/implementation process of the processing module 2801 in Figure 28 can be implemented by the processor 1001 in the terminal device 1000 shown in Figure 10 calling the computer execution instructions stored in the memory 1002.
  • the function/implementation process of the transceiver module 2802 in Figure 28 can be implemented by the transceiver 1003 in the terminal device 1000 shown in Figure 10 .
  • the function/implementation process of the transceiver module 2802 can be implemented through the input and output interface (or communication interface) of the chip or chip system, and the processing module 2801
  • the function/implementation process can be realized by the processor (or processing circuit) of the chip or chip system.
  • the first device 280 provided in this embodiment can perform the above synchronization method, the technology it can obtain For the effect, reference can be made to the above method embodiments, which will not be described again here.
  • FIG. 29 shows a schematic structural diagram of a second device 290.
  • the second device 290 includes a processing module 2901 and a transceiver module 2902.
  • the second device 290 may also include a storage module (not shown in Figure 29) for storing program instructions and data.
  • the transceiver module 2902 which may also be called a transceiver unit, is used to implement sending and/or receiving functions.
  • the transceiver module 2902 may be composed of a transceiver circuit, a transceiver, a transceiver or a communication interface.
  • the transceiver module 2902 may include a receiving module and a sending module, respectively configured to perform the receiving and sending steps performed by the second device in the above method embodiment, and/or to support the steps described herein.
  • the processing module 2901 can be used to perform steps of the processing type (such as determination, etc.) performed by the second device in the above method embodiment, and/or other processes used to support the technology described herein. For example:
  • Transceiver module 2902 configured to receive synchronization signals from the first device.
  • the processing module 2901 is used to perform time synchronization and/or frequency synchronization according to the synchronization signal.
  • the synchronization signal is generated by OFDM, and the synchronization signal includes a first signal and/or a second signal.
  • the first signal is used to determine the starting position of the time domain occupied by the data sent by the first device to the second device,
  • the second signal is used to determine the frequency of data sent by the second device to the first device.
  • the synchronization signal includes a first signal and a second signal, wherein the second signal is located after the first signal.
  • the first signal and the second signal are located within the same OFDM symbol.
  • the waveform of the synchronization signal is a CP-OFDM waveform.
  • the waveform of the synchronization signal is generated by CP-OFDM based on the first sequence.
  • the waveform of the synchronization signal is generated by DFT transform precoding.
  • the waveform of the synchronization signal is generated by DFT transform precoding, including: the waveform of the synchronization signal is the waveform obtained after the second sequence is subjected to CP-OFDM, wherein the second sequence is the first sequence.
  • the sequence obtained after DFT transform precoding is the waveform obtained after DFT transform precoding.
  • the time domain resource of the first signal includes the first K time units among the N time units corresponding to the useful signal in one OFDM symbol, where K is a positive integer, where the useful signal in one OFDM symbol is The part of OFDM symbols that carries useful information or useful data.
  • the time domain resource of the first signal also includes a partial time unit corresponding to the CP in the OFDM symbol in which the first signal is located.
  • the signals carried on the last S time units among the N time units corresponding to the useful signal in the OFDM symbol where the first signal is located are low-level signals, where the time length of the last S time units is greater than Or equal to the time length of the CP in the OFDM symbol where the first signal is located, where the useful signal in an OFDM symbol is the part of an OFDM symbol that carries useful information or useful data.
  • the time domain resource of the second signal includes M time units among the N time units corresponding to the useful signal in one OFDM symbol, where M is a positive integer, where the useful signal in one OFDM symbol is one OFDM symbol.
  • M is a positive integer
  • the useful signal in one OFDM symbol is one OFDM symbol.
  • the synchronization signal includes a second signal, wherein the waveform of the synchronization signal is generated by CP-OFDM after performing DFT transform precoding on the first sequence, and the first sequence includes a third sequence, and the first sequence includes a third sequence.
  • the three sequences are sequences used to generate the second signal; M satisfies the first condition, which includes:
  • N is L times M, and the number of elements contained in the first sequence is L times the number of elements contained in the third sequence, where N is a power of 2 and L is a positive integer.
  • M is the maximum value among multiple values that satisfy the first condition.
  • the transceiving module 2902 is also used to send capability information to the first device.
  • the capability information includes at least one of the following: whether the second device supports energy harvesting, whether the second device supports envelope detection, or whether the second device supports backscatter communication.
  • the second device 290 is presented in the form of dividing various functional modules in an integrated manner.
  • a “module” here may refer to a specific application specific integrated circuit (ASIC), a circuit, a processor and memory that executes one or more software or firmware programs, an integrated logic circuit, and/or other devices that can provide the above functions.
  • ASIC application specific integrated circuit
  • the second device 290 when the second device 290 is a terminal device, in terms of hardware implementation, those skilled in the art can imagine that the second device 290 may take the form of the terminal device 1000 shown in FIG. 10 .
  • the function/implementation process of the processing module 2901 in Figure 29 can be implemented by the processor 1001 in the terminal device 1000 shown in Figure 10 calling the computer execution instructions stored in the memory 1002.
  • the function/implementation process of the transceiver module 2902 in Figure 29 can be implemented by the transceiver 1003 in the terminal device 1000 shown in Figure 10 .
  • the function/implementation process of the transceiver module 2902 can be implemented through the input and output interface (or communication interface) of the chip or chip system, and the processing module 2901
  • the function/implementation process can be realized by the processor (or processing circuit) of the chip or chip system.
  • the second device 290 provided in this embodiment can perform the above synchronization method, the technical effects it can obtain can be referred to the above method embodiment, which will not be described again here.
  • the first device or the second device described in this application can also be implemented using the following: one or more field programmable gate arrays (FPGA), programmable logic devices (programmable logic device (PLD), controller, state machine, gate logic, discrete hardware components, any other suitable circuit, or any combination of circuits capable of performing the various functions described throughout this application.
  • FPGA field programmable gate arrays
  • PLD programmable logic device
  • controller state machine
  • gate logic discrete hardware components
  • discrete hardware components any other suitable circuit, or any combination of circuits capable of performing the various functions described throughout this application.
  • this application also provides a communication device, which includes a processor for implementing the method in any of the above method embodiments.
  • the communication device further includes a memory.
  • This memory is used to store necessary computer programs and data.
  • the computer program may include instructions, and the processor may call the instructions in the computer program stored in the memory to instruct the communication device to perform the method in any of the above method embodiments.
  • the memory may not be in the communication device.
  • the communication device further includes an interface circuit, which is a code/data reading and writing interface circuit.
  • the interface circuit is used to receive computer execution instructions (computer execution instructions are stored in the memory and may be directly read from memory, or possibly through other devices) and transferred to the processor.
  • the communication device further includes a communication interface, which is used to communicate with modules external to the communication device.
  • the communication device may be a chip or a chip system.
  • the communication device may be composed of a chip, or may include chips and other discrete devices, which is not specifically limited in the embodiments of the present application.
  • This application also provides a computer-readable storage medium on which a computer program or instructions are stored. When the computer program or instructions are executed by a computer, the functions of any of the above method embodiments are implemented.
  • This application also provides a computer program product, which implements the functions of any of the above method embodiments when executed by a computer.
  • the systems, devices and methods described in this application can also be implemented in other ways.
  • the device embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components may be combined or can be integrated into another system, or some features can be ignored, or not implemented.
  • the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection of the devices or units may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separate, that is, they may be located in one place, or they may be distributed to multiple network units. Components shown as units may or may not be physical units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.
  • each functional unit in each embodiment of the present application can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.
  • the above embodiments it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • a software program it may be implemented in whole or in part in the form of a computer program product.
  • the computer program product includes one or more computer instructions.
  • computer program instructions When computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.
  • the computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transferred from a website, computer, server, or data center Transmission to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) means.
  • the computer-readable storage medium can be any available medium that can be accessed by a computer or include one or more data storage devices such as servers and data centers that can be integrated with the medium.
  • the available media may be magnetic media (eg, floppy disk, hard disk, magnetic tape), optical media (eg, DVD), or semiconductor media (eg, solid state disk (SSD)), etc.
  • the computer may include the aforementioned device.

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Abstract

本申请实施例提供同步方法及通信装置，在NR系统引入Passive IoT或者ambient power-enabled IoT等低功耗通信系统的情况下，可以使得低功耗通信系统的同步信号与NR系统的子载波共存。方法包括：第一设备生成同步信号之后，向第二设备发送同步信号。其中，同步信号是通过正交频分复用OFDM的方式生成的，同步信号包括第一信号和/或第二信号，第一信号用于确定第一设备向第二设备发送的数据所占用的时域起始位置，第二信号用于确定第二设备向第一设备发送的数据的频率。

Description

同步方法及通信装置
本申请要求于2022年06月17日提交国家知识产权局、申请号为202210692328.9、申请名称为“同步方法及通信装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，尤其涉及同步方法及通信装置。
背景技术
随着物联网(internet-of-things,IoT)技术的发展，物联网终端设备的使用寿命成为IoT发展的瓶颈。其中，低功耗通信技术可以降低终端设备的功耗，以达到增加终端设备使用寿命的效果，使得无源物联网(passive IoT)或者环境供电物联网(ambient power-enabled IoT)成为可能。
目前，第三代合作伙伴项目(3rd generation partnership project,3GPP)在版本18(reversion18,R18)中计划让第五代(5th generation,5G)系统或新无线(new radio,NR)系统支持Passive IoT或者ambient power-enabled IoT等低功耗通信系统。然而，在低功耗通信系统的同步信号的相关规范中，未考虑同步信号与NR系统的兼容，因此低功耗通信系统的同步信号直接应用于NR系统时，该同步信号的时域波形与NR系统的子载波的时域波形之间存在干扰。因此，在NR系统引入Passive IoT或ambient power-enabled IoT等低功耗通信系统的情况下，如何使得低功耗通信系统的同步信号与NR系统的子载波共存，是目前亟待解决的问题。
发明内容
本申请实施例提供的同步方法及通信装置，在NR系统引入Passive IoT或ambient power-enabled IoT等低功耗通信系统的情况下，可以使得低功耗通信系统的同步信号与NR系统的子载波共存。
为达到上述目的，本申请的实施例采用如下技术方案：
第一方面，提供一种同步方法，该方法可以由第一设备执行，也可以由第一设备的部件，例如第一设备的处理器、芯片、或芯片系统等执行，还可以由能实现全部或部分第一设备功能的逻辑模块或软件实现。以下以该方法由第一设备执行为例进行说明。该方法包括：第一设备生成同步信号，并向第二设备发送该同步信号。其中，该同步信号是通过正交频分复用OFDM的方式生成的，该同步信号包括第一信号和/或第二信号，该第一信号用于确定该第一设备向第二设备发送的数据所占用的时域起始位置，该第二信号用于确定该第二设备向该第一设备发送的数据的频率。由于同步信号通过OFDM方式生成的，同步信号的时域波形可以是多个正交的子载波叠加之后的波形。因此，同步信号的时域波形与NR系统的子载波的时域波形之间为正交关系。因此，在NR系统引入Passive IoT或ambient power-enabled IoT等低功耗通信系统的情况下，可以使得低功耗通信系统的同步信号与NR系统的子载波共存。
第二方面，提供一种同步方法，该方法可以由第二设备执行，也可以由第二设备的部件，例如第二设备的处理器、芯片、或芯片系统等执行，还可以由能实现全部或部分第二设备功能的逻辑模块或软件实现。以下以该方法由第二设备执行为例进行说明。该方法包括：第二设备接收来自第一设备的同步信号，并根据该同步信号进行时间同步和/或频率同步。其中，该同步信号是通过正交频分复用OFDM的方式生成的，该同步信号包括第一信号和/或第二信号，该第一信号用于确定该第一设备向该第二设备发送的数据所占用的起始位置，该第二信号用于确定该第二设备向该第一设备发送的数据的频率。同步信号是通过OFDM的方式生成的，使得同步信号与第一设备向第二设备发送的数据的OFDM子载波之间彼此正交，进而第二设备接收信号时可以将同步信号的时域波形与第一设备发送的数据的OFDM子载波的时域波形完全分离，避免干扰。因此，在NR系统引入Passive IoT或ambient power-enabled IoT等低功耗通信系统的情况下，可以使得低功耗通信系统的同步信号与NR系统的子载波共存。
结合上述第一方面或第二方面，在一种可能的实现方式中，该同步信号包括该第一信号和该第二信号，其中，该第二信号位于该第一信号之后。基于该方案，第二设备检测到第一信号之后，第二设备可以检测到第二信号，获取第二信号的时间长度，进而结合下行数据中携带的DR，可以计算BLF。
结合上述第一方面或第二方面，在一种可能的实现方式中，该第一信号与该第二信号位于同一个OFDM符号内。基于该方案，第二设备检测到第一信号之后，可以确定开始接收第二信号。
结合上述第一方面或第二方面，在一种可能的实现方式中，该同步信号的波形是使用循环前缀的正交频分复用CP-OFDM波形。
结合上述第一方面或第二方面，在一种可能的实现方式中，该同步信号的波形是基于第一序列，通过CP-OFDM的方式生成的。
结合上述第一方面或第二方面，在一种可能的实现方式中，该同步信号的波形是通过离散傅里叶变换DFT变换预编码的方式生成的。
结合上述第一方面或第二方面，在一种可能的实现方式中，同步信号的波形是通过离散傅里叶变换DFT变换预编码的方式生成的，包括：该同步信号的波形是第二序列经过CP-OFDM后得到的波形，其中，该第二序列为第一序列进行DFT变换预编码后得到的序列。
结合上述第一方面或第二方面，在一种可能的实现方式中，该第一信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的前K个时间单元，K为正整数，其中，该一个OFDM符号中的有用信号为一个OFDM符号中除循环前缀CP之外的部分。基于该方案，第二设备可以在第二信号和下行数据之前，先检测到第一信号，以便于后续下行数据和第二信号的接收。并且，从发送信号的时域资源利用率的角度，第一信号仅占用OFDM符号的部分时域资源，因此可以利用OFDM符号中空闲的时域资源传输其他内容，比如第二信号，数据0，或者RTcal等。
结合上述第一方面或第二方面，在一种可能的实现方式中，该第一信号的时域资源还包括该第一信号所在的OFDM符号中CP对应的部分时间单元。基于该方案，在第一信号为低电平信号的情况下，通过在第一信号的时域资源增加CP对应的部分时 间单元，使得低电平信号的持续时间足够长，进而第一信号可以与第二信号的低电平部分和/或下行数据的低电平部分进行更好地区分。如此，第二设备接收到的信号时，可以确定接收信号中时间长度最长的低电平信号为第一信号。
结合上述第一方面或第二方面，在一种可能的实现方式中，该第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号为低电平信号，其中，该后S个时间单元的时间长度大于或等于该第一信号所在的OFDM符号中CP的时间长度，该一个OFDM符号中的有用信号为一个OFDM符号中除CP之外的部分。也就是说，第一信号所在的OFDM符号中有用信号对应的后S个时间单元上承载的信号为低电平信号，可以确保CP的信号的电平为低电平。如此，可以增加第一信号的低电平部分的持续时间。
结合上述第一方面或第二方面，在一种可能的实现方式中，该第二信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的M个时间单元，M为正整数，该一个OFDM符号中的有用信号为一个OFDM符号中除CP之外的部分。
结合上述第一方面或第二方面，在一种可能的实现方式中，该同步信号包括该第二信号，其中，该同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的，该第一序列包括第三序列，该第三序列为用于生成该第二信号的序列；M满足第一条件，该第一条件包括：N为M的L倍，且该第一序列包含的元素个数为该第三序列包含的元素个数的L倍，其中，N为2的幂次方，L为正整数。
结合上述第一方面或第二方面，在一种可能的实现方式中，M为满足该第一条件的多个数值中的最大值。基于该方案，在第二设备通过时钟边沿测量第二信号的时间长度的情况下，可以减小测量误差。
结合上述第一方面，在一种可能的实现方式中，该方法还包括：第一设备接收来自第二设备的能力信息，该能力信息包括以下至少一项：第二设备是否支持能量收集，第二设备是否支持包络检波，或者第二设备是否支持反向散射通信。
结合上述第二方面，在一种可能的实现方式中，该方法还包括：第二设备向第一设备发送能力信息，该能力信息包括以下至少一项：第二设备是否支持能量收集，第二设备是否支持包络检波，或者第二设备是否支持反向散射通信。
第三方面，提供了一种通信装置用于实现上述各种方法。该通信装置可以为上述第一方面中的第一设备，或者包含上述第一设备的装置，或者上述第一设备中包含的装置，比如芯片；或者，该通信装置可以为上述第二方面中的第二设备，或者包含上述第二设备的装置，或者上述第二设备中包含的装置。所述通信装置包括实现上述方法相应的模块、单元、或手段(means)，该模块、单元、或means可以通过硬件实现，软件实现，或者通过硬件执行相应的软件实现。该硬件或软件包括一个或多个与上述功能相对应的模块或单元。
在一些可能的设计中，该通信装置可以包括处理模块和收发模块。该收发模块，也可以称为收发单元，用以实现上述任一方面及其任意可能的实现方式中的发送和/或接收功能。该收发模块可以由收发电路，收发机，收发器或者通信接口构成。该处理模块，可以用于实现上述任一方面及其任意可能的实现方式中的处理功能。
在一些可能的设计中，收发模块包括发送模块和接收模块，分别用于实现上述任 一方面及其任意可能的实现方式中的发送和接收功能。
第四方面，提供了一种通信装置，包括：处理器和存储器；该存储器用于存储计算机指令，当该处理器执行该指令时，以使该通信装置执行上述任一方面所述的方法。该通信装置可以为上述第一方面中的第一设备，或者包含上述第一设备的装置，或者上述第一设备中包含的装置，比如芯片；或者，该通信装置可以为上述第二方面中的第二设备，或者包含上述第二设备的装置，或者上述第二设备中包含的装置。
第五方面，提供一种通信装置，包括：处理器和通信接口；该通信接口，用于与该通信装置之外的模块通信；所述处理器用于执行计算机程序或指令，以使该通信装置执行上述任一方面所述的方法。该通信装置可以为上述第一方面中的第一设备，或者包含上述第一设备的装置，或者上述第一设备中包含的装置，比如芯片；或者，该通信装置可以为上述第二方面中的第二设备，或者包含上述第二设备的装置，或者上述第二设备中包含的装置。
第六方面，提供了一种通信装置，包括：至少一个处理器；所述处理器用于执行存储器中存储的计算机程序或指令，以使该通信装置执行上述任一方面所述的方法。该存储器可以与处理器耦合，或者，也可以独立于该处理器。该通信装置可以为上述第一方面中的第一设备，或者包含上述第一设备的装置，或者上述第一设备中包含的装置，比如芯片；或者，该通信装置可以为上述第二方面中的第二设备，或者包含上述第二设备的装置，或者上述第二设备中包含的装置。
第七方面，提供了一种计算机可读存储介质，该计算机可读存储介质中存储有计算机程序或指令，当其在通信装置上运行时，使得通信装置可以执行上述任一方面所述的方法。
第八方面，提供了一种包含指令的计算机程序产品，当其在通信装置上运行时，使得该通信装置可以执行上述任一方面所述的方法。
第九方面，提供了一种通信装置(例如，该通信装置可以是芯片或芯片系统)，该通信装置包括处理器，用于实现上述任一方面中所涉及的功能。
在一些可能的设计中，该通信装置包括存储器，该存储器，用于保存必要的程序指令和数据。
在一些可能的设计中，该装置是芯片系统时，可以由芯片构成，也可以包含芯片和其他分立器件。
可以理解的是，第三方面至第九方面中任一方面提供的通信装置是芯片时，上述的发送动作/功能可以理解为输出，上述的接收动作/功能可以理解为输入。
其中，第三方面至第九面中任一种设计方式所带来的技术效果可参见上述第一方面或第二方面中不同设计方式所带来的技术效果，在此不再赘述。
第十方面，提供一种通信系统，该通信系统包括上述方面所述的第一设备和上述方面所述的第二设备。
附图说明
图1为本申请实施例提供的一种反向散射通信系统的架构示意图；
图2为本申请实施例提供的一种超高频射频识别系统的架构示意图；
图3为本申请实施例提供的一种基于唤醒机制的通信系统的架构示意图；
图4为本申请实施例提供的数据0的PIE符号和数据1的PIE符号的符号示意图；
图5为本申请实施例提供的射频识别系统的下行信号的帧结构示意图；
图6为本申请实施例提供的前导码作为帧头的PIE符号示意图；
图7为本申请实施例提供的帧同步码作为帧头的PIE符号示意图；
图8为本申请实施例提供的一个通信系统的架构示意图；
图9为本申请实施例提供的另一个通信系统架构示意图；
图10为本申请实施提供的终端设备和接入网设备的硬件结构示意图；
图11为本申请实施例提供的同步方法流程示意图；
图12为本申请实施例提供的一种同步信号的时域资源的示意图；
图13为本申请实施例提供的另一种同步信号的时域资源的示意图；
图14为本申请实施例提供的另一种同步信号的时域资源的示意图；
图15为本申请实施例提供的一种OFDM符号的结构示意图；
图16为本申请实施例提供的另一种同步信号的时域资源的示意图；
图17为本申请实施例提供的一种第一信号与第二信号之间的时域位置关系示意图；
图18为本申请实施例提供的另一种第一信号与第二信号之间的时域位置关系示意图；
图19为本申请实施例提供的一种同步信号的波形生成方式的模块框架示意图；
图20为本申请实施例提供的另一种同步信号的波形生成方式的模块框架示意图；
图21为本申请实施例提供的第一信号的时域资源示意图；
图22为本申请实施例提供的一种下行信号的结构示意图；
图23为本申请实施例提供的NR系统一个时隙内每个OFDM符号的时间长度示意图；
图24为本申请实施例提供的第一阈值与第二阈值取值范围示意图；
图25为本申请实施例提供的一种第二信号的时域资源示意图；
图26为本申请实施例提供的另一种下行信号的时域资源示意图；
图27为本申请实施例提供的时钟计数测量信号时间长度示意图；
图28为本申请实施例提供的一种第一设备的结构示意图；
图29为本申请实施例提供的一种第二设备的结构示意图。
具体实施方式
为方便理解本申请实施例提供的技术方案，首先给出本申请相关技术的简要介绍。简要介绍如下：
第一，IoT：
IoT是“物物相连的互联网”。它将互联网的用户端扩展到了任何物品与物品之间，使得在任何物品与物品之间可以进行信息交换和通信。这样的通信方式也称为机器间通信(machine type communications,MTC)。其中，通信的节点称为MTC终端或MTC设备。典型的IoT业务包括：智能电网、环境监测、智能农业以及智能抄表等业务。
由典型的IoT业务可知，在大多数情况下，IoT需要部署海量的MTC终端，这不 仅要求能够以较低的成本获得并使用MTC终端，而且需要MTC终端能够长期使用。然而，在大多数的业务场景下，无法为海量的MTC终端提供外部供电电源，因此MTC终端是通过电池来供电的。但是，电池的容量有限，加之MTC终端本身的功耗，使得MTC终端的使用时间有限，增加了MTC终端的维护难度和维护成本，因此制约了IoT的发展。
为满足上述需求，在IoT中可以采用无线功率传输技术、包络检波解调技术或者反射散射调制等低功耗通信技术。其中，反向散射(backscatter)通信技术是低功耗通信技术的一种，具有低成本、超低功耗等特点，因此反向散射通信技术可以增加MTC终端的使用时间。
第二，反向散射通信技术：
反向散射通信技术是基于无线功率传输、包络检波解调和反射散射调制技术的通信技术。图1示例出了本申请实施例所涉及的反向散射通信系统的架构图。如图1所示，反向散射通信系统可以包括：激励器101，接收器102，以及反射器103。其中，反向散射通信系统的通信链路包括：下行链路和上行链路。下行链路可以是指激励器101向反射器103发送信号的通信链路。上行链路可以是指反射器103向接收器102发送信号的通信链路。
其中，激励器101和接收器102可以部署在同一个设备内，或者激励器101与接收器102可以分离。
其中，反射器103根据自身是否有电池供电，可以分为无源(passive)反射器和半无源(semi-passive)反射器。无源反射器自身没有电池供电，且由于激励器101发送的下行信号为射频信号，因此无源反射器需要对激励器101发送的下行信号进行整流，将整流后输出的直流信号作为电源，进而为无源反射器的内部电路供电。半无源发射器由于自身具有电池，因此半无源发射器不依赖激励器101发送的下行信号供电。
示例性的，在下行链路中，激励器101可以采用幅移键控(amplitude shift keying,ASK)的方式调制下行信号，反射器103可以采用基于低功耗的包络检波器解调下行信号。在上行链路中，反射器103可以基于欲发送的信息比特改变天线的负载，使得该信息比特可以调制到入射的载波(即下行信号)上，之后将下行信号反射至接收器102，进而实现上行信号的无线传输。如此，反射器103不需要射频振荡器，功率放大器，以及低噪声放大器等高功耗器件，使得反向散射通信系统具有低成本和超低功耗的特点。
下面结合上述反向散射通信技术，以超高频(ultra-high frequency,UHF)射频识别(radio frequency dentification,RFID)系统为例，示例性说明IoT与反向散射通信技术结合的通信系统的架构。
示例性的，图2示例出了本申请实施例所涉及的UHF RFID系统架构图。如图2所示，UHF RFID系统可以包括：读写器201和标签202。一种可能的实现方式中，UHF RFID系统将图1中所示的激励器101和接收器102设置于同一设备内，即读写器201可以包括激励器101和接收器102。UHF RFID系统中的标签202可以为图1中所示的反射器103。其中，读写器201和标签202还可以称为MTC终端或MTC设备。
其中，UHF RFID系统的通信链路同样包括下行链路和上行链路。下行链路可以 是指读写器201向标签202发送信号的通信链路。上行链路可以是指标签202向读写器201发送信号的通信链路。
其中，读写器201向标签202发送下行信号。下行信号可以包括下行激励信号和数据。其中，下行激励信号可以用于为标签202提供能量。数据可以用于向标签202传输下行信令，以及用于标签202使用反向散射技术向读写器201发送上行信号。如此，读写器201通过发送下行信号和接收上行信号，可以识别标签202的标识(identity,ID)，进而对标签202进行读或写操作。
以下行信令为查询命令(Query)为例，数据中承载的信息可以包括：命令字，划分比(divide ratio,DR)，编码方式，选择命令(select)配置参数，或者会话层(session)等。
需要说明，“数据”可以是指发送端需要发送给接收端的数据。该数据可以称为有效数据，或者有用数据。换言之，“数据”，“有效数据”，或者“有用数据”可以相互替换表述，在此统一说明，以下不再赘述。
第三，基于唤醒机制的通信系统：
基于唤醒机制的通信系统也可以降低MTC终端的功耗，进而增加MTC终端的使用时间。图3示例出了本申请实施例所涉及的基于唤醒机制的通信系统的架构图。如图3所示，基于唤醒机制的通信系统可以包括：网络设备301和终端设备302。其中，网络设备301和终端设备302还可以称为MTC终端或MTC设备。在该系统中，终端设备302可以处于省电模式(power savings mode,PSM)或者睡眠模式，网络设备301可以对处于PSM或者睡眠模式的终端设备302发送下行唤醒信号(wake-up signal,WUS)，通知终端设备302收发数据，进而可以达到终端设备302节能的效果。
其中，网络设备301可以是NR系统中的接入网设备。或者，网络设备301可以是UHF RFID系统中的读写器201。
示例性的，唤醒信号的调制方式可以采用开关键控(on-off keying,OOK)或ASK，使得终端设备302可基于低功耗的包络检波器解调网络设备301发送的下行信号。如此，可以降低终端设备302的待机功耗，延长终端设备302的待机寿命。
需要说明的是，上述反向散射通信技术可以与唤醒机制相互结合，例如图2中的标签202可以处于PSM或者睡眠模式，读写器201可以向处于PSM或者睡眠模式的标签202发送唤醒信号，通知标签202收发数据。
应理解，上述基于反向散射通信技术的通信系统和基于唤醒机制的通信系统通常为异步系统，即读写器201与标签202之间未时间同步，或者网络设备301与终端设备302之间未时间同步。因此，需要在下行信号的数据之前插入前导码(preamble)或者同步信号，以供标签202或终端设备302完成下行信号的检测和同步。
第四，脉冲间隔编码(pulse interval encoding,PIE)：
在国际标准化组织(international standardization organization,ISO)或国际电工技术委员会(international electrotechnical commission,IEC)18000-6C标准中，规定RFID系统的下行信号中的数据采用PIE的方式进行编码。其中，PIE通过高低电平的时间长度的不同来定义数据为“0”或为“1”。图4示例出了数据0(data-0)的PIE符号和数据1(data-1)的PIE符号。如图4所示，数据0的时间长度Tdata-0为A型参考间隔(type A reference interval,Tari)， 其中低电平的时间长度为脉冲宽度(pulse width,PW)。数据1的时间长度Tdata-1的取值范围为[1.5Tari,2Tari]，其中低电平长度为PW。其中，Tari的取值范围为[6.25μs,25μs]，PW的取值范围为[max(0.265Tari,2μs),0.525Tari]，max()表示取最大值。
需要说明，在本申请实施例中，“时间长度”的含义与“持续时间”的含义相同，均表示为信号，符号，或者电平等，在时域上所占用的时间长度。换言之，“持续时间”与“时间长度”可以相互替换表述，在此统一说明，以下不再赘述。
如上所述，为使得标签202完成下行信号的检测和同步，RFID系统的下行信号中需要在下行信号的数据之前插入前导码或者同步信号。相应地，在ISO/IEC 18000-6C标准中，规定了如何在下行信号的数据之前插入前导码或者同步信号，具体如下：
示例性的，如图5所示，为RFID系统的下行信号的帧结构示意图。其中，RFID系统的下行信号的帧结构，可以包括：帧头501，下行数据502，以及校验码503。其中，帧头501为同步信号，用于标签202完成下行信号的检测和同步。下行数据502用于承载下行信令。校验码503用于检测数据传输过程中是否发生错误。其中，校验码503可以采用5比特循环冗余校验(cyclic redundancy check,CRC)码，或者采用16比特CRC码。
其中，根据下行信令的不同，帧头501可以采用前导码或者帧同步(Frame-Sync)码。示例性的，若读写器201发送的下行信令为查询命令，读写器201可以采用前导码作为帧头。若读写器201发送除查询命令之外的其他命令，读写器201可以采用帧同步码作为帧头。
示例性的，如图6所示，为前导码作为帧头501的PIE符号示意图。其中，前导码的PIE符号，可以包括：定界符(delimiter)，数据0，读写器到标签校准(reader-tag calibration,RTcal)，以及标签到读写器校准(tag-reader calibration,TRcal)。
其中，定界符用于指示下行信号的下行数据502的时域起始位置。示例性的，定界符为连续的低电平信号。其中，定界符的时间长度Tdelimiter为12.5μs，容差在5％范围内，即定界符的时间长度Tdelimiter的取值范围为[0.95×12.5μs,1.05×12.5μs]。
其中，RTcal可以用于作为标签202解码PIE符号的基准。RTcal的时间长度TRTcal为数据0的时间长度Tari与数据1的时间长度Tdata-1之和，即RTcal的时间长度TRTcal的取值范围为[2.5Tari,3Tari]。
示例性的，当PIE符号的时间长度小于RTcal的时间长度TRTcal的一半时，标签202可以确定该PIE符号为数据0；当PIE符号的时间长度大于RTcal的时间长度TRTcal的一半时，标签202可以确定该PIE符号为数据1。
其中，TRcal用于结合DR计算标签202向读写器201发送的数据的上行反向散射链路频率(backscatter-link frequency,BLF)。其中，DR由查询命令中的下行数据502携带。DR可以取值为8或64/3。其中，标签202可以根据如下公式(1)计算BLF：
其中，TTRcal表示TRcal的时间长度。TTRcal的取值范围为[1.1TRTcal,3TRTcal]。
示例性的，如图7所示，为帧同步码作为帧头501的PIE符号示意图。其中，帧同步码的PIE符号，可以包括：定界符，数据0，以及RTcal。其中，帧同步码的PIE符号的定界符，数据0，以及RTcal的配置可以参考上述前导码的PIE符号的定界符，数据0，以及RTcal，在此不再赘述。
如上所述，passive IoT或者ambient power-enabled IoT等低功耗通信系统可以是 具备以下技术之一的通信系统：能量收集(energy harvesting)技术、包络检波解调技术或者反向散射(backscatter)调制技术。其中，低功耗通信系统可以为异步通信系统，即发射端设备与接收端设备未严格同步，因此ISO或IEC等相关组织，定义了下行信号中关于同步信号的相关规范，以供接收端设备完成下行信号的检测和同步。
第五，正交频分复用(orthogonal frequency division multiplexing,OFDM)：
目前，3GPP支持在NR系统的上行链路和下行链路的传输方案中使用OFDM技术。其中，OFDM技术是一种多载波传输技术，OFDM技术的原理为：在频域内划分多个子信道，将待传输的数据进行串并转换，得到并行传输的多组数据，之后将每组数据调制到每个子信道的子载波(subcarrier)上进行传输。因此在时域上，待传输的数据通过多个在空间中叠加的子载波进行传输，其中多个子载波之间彼此正交，进而接收信号时可以将多个子载波分离，之后分别对每个子载波进行解调，从而得到待传输的数据。
第六，NR系统相关术语解释：
1、通用概念：
NR系统的时域以时间单位Tc＝1/(Δfmax·Nf)表示。其中，Δfmax＝480×103Hz，Nf＝4096。
常数κ＝Ts/Tc＝64。其中，Ts＝1/(Δfref·Nf,ref)，Δfref＝15×103Hz，Nf,ref＝2048。
2、参数集(numerology)：
NR系统支持的传输参数集如表1所示。在表1中，第一列为子载波间隔(subcarrier space,SCS)配置μ，第二列表示子载波间隔，第三列表示循环前缀(cyclic prefix,CP)。
表1
其中，常规CP(normal CP)和扩展(extended CP)的时间长度满足其中如公式(2)：
其中，l为一个子帧内OFDM符号的编号。
3、帧(frame)和子帧(subframe)：
下行和上行传输被组成持续时间为Tf＝(ΔfmaxNf/100)＝10ms的帧。每个帧由十个持续时间为Tsf＝(ΔfmaxNf/1000)＝1ms的子帧组成。例如，一个帧可以包括子帧#0～子帧#9。每个子帧的连续OFDM符号数为每个帧被分成两个大小相同的半帧，即半帧#0和半帧#1。每个半帧包括五个子帧。示例性的，半帧#0由子帧#0～子帧#4组成，半帧#1由子帧#5～子帧#9组成。
4、时隙(slot)：
对于子载波间隔配置μ，时隙在一个子帧内按升序编号以 及在一个帧内按升序编号排列。在一个时隙中有个连续的OFDM符号，其中数值取决于CP，如表2和表3所示。一个子帧中时隙的开始与同一子帧中的OFDM符号的开始在时间上对齐。示例性的，在一个时隙内包括14个OFDM符号的情况下，OFDM符号可以按时间先后排序为：OFDM符号#0～OFDM符号#13。
一个时隙中的OFDM符号可能包括3种类型：下行符号、上行符号和灵活符号。上行符号只能用于上行传输。下行符号只能用于下行传输。灵活符号没有确定的传输方向，可以根据控制信令的指示用于进行上行传输或者下行传输。
表2
表3
如上所述，在基于OFDM技术的传输方案中，关键在于接收信号时多个子载波的时域波形能够完全分离以及彼此互不干扰。然而，在NR系统引入Passive IoT或者ambient power-enabled IoT等低功耗通信系统的情况下，上述低功耗通信系统所使用的同步信号(帧头501)的时域波形与NR系统中传输数据的子载波的时域波形之间不是正交关系，若RFID系统所使用的同步信号直接应用于NR系统，同步信号与NR系统中传输数据的子载波之间相互干扰，影响通信性能。
鉴于此，本申请实施例提供一种同步方法，在NR系统引入Passive IoT或ambient power-enabled IoT等低功耗通信系统的情况下，可以使得Passive IoT或ambient power-enabled IoT等低功耗通信系统的同步信号与NR系统的子载波共存。
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述。其中，在本申请的描述中，除非另有说明，“/”表示前后关联的对象是一种“或”的关系，例如，A/B可以表示A或B；本申请中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况，其中A,B可以是单数或者复数。并且，在本申请的描述中，除非另有说明，“多个”是指两个或多于两个。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a，b，或c中的至少一项(个)，可以表示：a，b，c，a-b，a-c，b-c，或a-b-c，其中a，b，c可以是单个，也可以是多个。另外，为了便于清楚描述本申请实施例的技术方案，在本申请的实施例中，采用了“第一”、“第二”等字样对功能和作用基本相同的相同项或相似项进行区分。本领域技术人员可以理解“第一”、“第二”等字样并不对数量和执行次序进行限定，并且“第一”、“第二”等字样也并不限定一定不同。
此外，本申请实施例描述的网络架构以及业务场景是为了更加清楚的说明本申请实施例的技术方案，并不构成对于本申请实施例提供的技术方案的限定，本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本申请实施例提供的技术方案对于类似的技术问题，同样适用。
本申请实施例的技术方案可以应用于NR系统。本申请实施例的技术方案还可以应用于其他通信系统。例如：长期演进(long term evolution,LTE)系统，LTE频分双工(frequency division duplex,FDD)系统，LTE时分双工(time division duplex,TDD)系统，通用移动通信系统(universal mobile telecommunication system,UMTS)，全球互联微波接入(worldwide interoperability for microwave access,WiMAX)通信系统，以及基于唤醒机制的通信系统等。本申请中涉及的NR系统包括非独立组网(non-standalone,NSA)的NR系统或独立组网(standalone，SA)的NR系统。本申请提供的技术方案还可以应用于未来的通信系统，如第六代移动通信系统。通信系统还可以是陆上公用移动通信网(public land mobile network,PLMN)网络、设备到设备(device-to-device,D2D)通信系统、机器到机器(machine to machine,M2M)通信系统、IoT通信系统或者其他通信系统。
图8为本申请实施例提供的一个通信系统的架构示意图。如图8所示，该通信系统包括：第一设备801和第二设备802。其中，第一设备801为同步信号的发送端，第二设备802为同步信号的接收端。其中，结合图2所示的UHF RFID系统，第一设备801可以是读写器201，第二设备802可以是标签202。
其中，结合图3所示的基于唤醒机制的系统，第一设备801可以是网络设备301，第二设备802可以是终端设备302。
其中，结合NR系统，第一设备801的具体设备形态可以包括：NR系统中的接入网设备，NR系统中的终端设备。第二设备802的具体设备形态可以包括：NR系统中的终端设备。第一设备801以及第二设备802可以使用OFDM技术传输数据。示例性的，第一设备801向第二设备802发送的数据可以通过OFDM子载波传输。或者，第二设备802向第一设备801发送的数据可以通过OFDM子载波传输。
下面以第一设备801与第二设备802进行交互为例进行说明。
一种可能的实现方式中，第一设备801生成同步信号，以及向第二设备802发送该同步信号。其中，同步信号是通过OFDM的方式生成的。该同步信号可以包括第一信号和/或第二信号。其中，第一信号用于确定第一设备801向第二设备802发送的数据所占用的时域起始位置。第二信号用于确定第二设备802向第一设备801发送的数据的频率。相应地，第二设备802接收来自第一设备801的同步信号，并根据该同步信号进行时间同步和/或频率同步。
上述方案的具体实现将在下述实施例中详细阐述，在此不再赘述。
在本申请实施例中，第一设备可以通过OFDM的方式生成同步信号，使得同步信号与第一设备向第二设备发送的数据(以下简称为下行数据)的OFDM子载波之间彼此正交，进而第二设备802接收信号时可以将同步信号的时域波形与承载下行数据的OFDM子载波的时域波形完全分离，避免干扰。因此，在NR系统引入Passive IoT或者ambient power-enabled IoT等低功耗通信系统的情况下，本申请实施例提供的同步方法 可以使得低功耗通信系统的同步信号与NR系统的子载波共存。
下面结合NR系统，进一步说明本申请实施例提供的同步方法可以应用的通信系统架构。
如图9所示，为本申请提供的另一个通信系统900。该通信系统900可以包括：接入网设备#1～#2，终端设备#1～#8。其中，接入网设备#1可以直接向终端设备#1～终端设备#6发送数据，进而接入网设备#1可以是第一设备801，终端设备#1～终端设备#6可以是第二设备802；接入网设备#1可以通过接入网设备#2向终端设备#7和/或终端设备#8发送数据，进而接入网设备#2可以是第一设备801，终端设备#7或终端设备#8可以是第二设备802。
其中，在通信系统900中，接入网设备#2，终端设备#7，以及终端设备#8可以组成另一个通信系统910。在该通信系统910中，接入网设备#2可以直接向终端设备#7或终端设备#8发送数据，进而接入网设备#2可以是第一设备801，终端设备#7或终端设备#8可以是第二设备802。
其中，在通信系统900中，终端设备#4～终端设备#6可以组成另一个通信系统920。其中，在该通信系统920中，终端设备#4可以直接向终端设备#5和/或终端设备#6发送数据，进而终端设备#4可以是第一设备801，终端设备#5或终端设备#6可以是第二设备802。
需要说明，由于在上述通信系统900中，本申请实施例中的第一设备801可以是接入网设备或终端设备，第二设备802可以是终端设备，为方便理解本申请实施例中的第一设备801和第二设备802的实体形态，下面以第一设备801为接入网设备，第二设备802为终端设备为例，示例性说明第一设备801和第二设备802的硬件结构。
如图10所示，为本申请实施例提供的终端设备1000和接入网设备1010的硬件结构示意图。
终端设备1000包括至少一个处理器1001(图10中示例性的以包括一个处理器1001为例进行说明)、至少一个存储器1002(图10中示例性的以包括一个存储器1002为例进行说明)和至少一个收发器1003(图10中示例性的以包括一个收发器1003为例进行说明)。可选地，终端设备1000还可以包括输出设备1004和输入设备1005。
处理器1001、存储器1002和收发器1003通过通信线路相连接。通信线路可包括一通路，在上述组件之间传送信息。
处理器1001可以是一个通用中央处理器(central processing unit,CPU)，微处理器，特定应用集成电路(application-specific integrated circuit,ASIC)，或者一个或多个用于控制本申请方案程序执行的集成电路。在具体实现中，作为一种实施例，处理器1001也可以包括多个CPU，并且处理器1001可以是一个单核(single-CPU)处理器或多核(multi-CPU)处理器。这里的处理器可以指一个或多个设备，电路，或用于处理数据(例如计算机程序指令)的处理核。
存储器1002可以是只读存储器(read-only memory,ROM)或可存储静态信息和指令的其他类型的静态存储设备，随机存取存储器(random access memory,RAM)或者可存储信息和指令的其他类型的动态存储设备，也可以是电可擦可编程只读存储器(electrically erasable programmable read-only memory,EEPROM)，只读光盘(compact  disc read-only memory，CD-ROM)或其他光盘存储，光碟存储(包括压缩光碟，激光碟，光碟，数字通用光碟，或者蓝光光碟等)，磁盘存储介质或者其他磁存储设备，或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，但不限于此。存储器1002可以是独立存在，通过通信线路与处理器1001相连接。存储器1002也可以和处理器1001集成在一起。
其中，存储器1002用于存储执行本申请方案的计算机执行指令，并由处理器1001来控制执行。具体的，处理器1001用于执行存储器1002中存储的计算机执行指令，从而实现本申请实施例中所述的同步方法。可选地，本申请实施例中的计算机执行指令也可以称之为应用程序代码或者计算机程序代码，本申请实施例对此不作具体限定。
收发器1003可以使用任何收发器一类的装置，用于与其他设备或通信网络通信，如以太网，无线接入网(radio access network,RAN)，或者无线局域网(wireless local area networks,WLAN)等。收发器1003包括发射机Tx和接收机Rx。
输出设备1004和处理器1001通信，可以以多种方式来显示信息。例如，输出设备1004可以是液晶显示器(liquid crystal display,LCD)，发光二级管(light emitting diode,LED)显示设备，阴极射线管(cathode ray tube,CRT)显示设备，或投影仪(projector)等。
输入设备1005和处理器1001通信，可以以多种方式接受用户的输入。例如，输入设备1005可以是鼠标、键盘、触摸屏设备或传感设备等。
网络设备1010包括至少一个处理器1011(图10中示例性的以包括一个处理器1011为例进行说明)、至少一个存储器1012(图10中示例性的以包括一个存储器1012为例进行说明)、至少一个收发器1013(图10中示例性的以包括一个收发器1013为例进行说明)和至少一个网络接口1014(图10中示例性的以包括一个网络接口1014为例进行说明)。处理器1011、存储器1012、收发器1013和网络接口1014通过通信线路相连接。其中，网络接口1014用于通过链路(例如S1接口)与核心网设备连接，或者通过有线或无线链路(例如X2接口)与其它网络设备的网络接口进行连接(图10中未示出)，本申请实施例对此不作具体限定。另外，处理器1011、存储器1012和收发器1013的相关描述可参考终端设备1000中处理器1001、存储器1002和收发器1003的描述，在此不再赘述。
可选地，本申请实施例中的接入网设备1010可以是接入核心网的装置或者可用于接入核心网的装置中的芯片等，本申请实施例对此不作具体限定。其中，接入核心网的装置例如可以是长期演进LTE系统中的基站，全球移动通信系统(global system for mobile communication，GSM)中的基站，UMTS中的基站，NR系统中的基站，PLMN中的基站，宽带网络业务网关(broadband network gateway,BNG)，汇聚交换机，非3GPP(non 3GPP)网络设备等。基站可以包括各种形式的基站，例如：宏基站，微基站(也称为小站)，中继站，以及接入点等，本申请实施例对此不作具体限定。
可选地，本申请实施例中的接入网设备1010可以支持反向散射通信技术。
可选地，本申请实施例中的接入网设备1010可以支持发送唤醒信号。
可选地，本申请实施例中的接入网设备1010也可以称之为接入设备，本申请实施例对此不作具体限定。
可选地，本申请实施例中的终端设备1000可以是用于实现无线通信功能的设备，例如终端或者可用于终端中的芯片等，本申请实施例对此不作具体限定。其中，终端可以是LTE系统，GSM，UMTS，NR系统，未来演进的PLMN中的用户设备(user equipment,UE)，接入终端、终端单元，终端站，移动站，移动台，远方站，远程终端，移动设备，无线通信设备，终端代理或终端装置等。接入终端可以是蜂窝电话，无绳电话，会话启动协议(session initiation protocol,SIP)电话，无线本地环路(wireless local loop,WLL)站，个人数字处理(personal digital assistant,PDA)，具有无线通信功能的手持设备，计算设备或连接到无线调制解调器的其它处理设备，车载设备，可穿戴设备，虚拟现实(virtual reality，VR)终端设备，增强现实(augmented reality，AR)终端设备，工业控制(industrial control)中的无线终端，无人驾驶(self driving)中的无线终端、远程医疗(remote medical)中的无线终端，智能电网(smart grid)中的无线终端，运输安全(transportation safety)中的无线终端，智慧城市(smart city)中的无线终端，智慧家庭(smart home)中的无线终端等。终端设备1000可以是移动的，也可以是固定的。
可选地，本申请实施例中的终端设备1000可以支持反向散射通信技术。
可选地，本申请实施例中的终端设备1000可以支持接收唤醒信号。
可选地，本申请实施例中终端设备1000还可以称为标签，MTC终端，或者NR终端等，本申请实施例对此不作具体限定。
下面将结合图8至图10，对本申请实施例提供的同步方法进行展开说明。
需要说明的是，本申请下述实施例中各个设备之间的信号名字或信号中各参数的名字等只是一个示例，具体实现中也可以是其他的名字，本申请实施例对此不作具体限定。
以图8所示的第一设备801与第二设备802进行交互为例，如图11所示，为本申请实施例提供的一种同步方法，包括如下步骤：
S1101、第一设备生成同步信号。其中，同步信号是通过OFDM的方式生成的。也就是说，同步信号的时域波形可以是多个正交的子载波叠加之后的波形。进而，同步信号的时域波形与NR系统的子载波的时域波形之间为正交关系。
可选地，同步信号可以是通过传统OFDM(conventional OFDM)的方式生成的。示例性的，第一设备可以将同步信号的序列映射到子载波上，之后进行快速傅里叶逆变换(inverse fast fourier transform,IFFT)，生成同步信号的OFDM时域波形。
需要说明，同步信号还可以是通过滤波OFDM(filtered-OFDM,F-OFDM)的方式生成的。或者，本申请实施例中，同步信号还可以是通过其他OFDM的方式生成的，本申请实施对此不作具体限定。
需要说明，本申请实施例中，“序列”与“数据”的含义可以相同，其中“数据”可以表示为多个“0”或“1”符号/元素构成的“序列”，比如序列[01010101101]可以表示为第一设备或第二设备待发送的数据。换言之，“序列”与“数据”可以相互替换表述，在此统一说明，以下不再赘述。
可选地，本申请实施例中，同步信号的时域波形是通过OFDM的方式生成的。或者，同步信号的时域波形是OFDM波形。
可以理解，由于第一设备与第二设备之间的下行链路采用基于OFDM技术的传输方案，因此第一设备向第二设备发送的同步信号或数据的最小传输单元是一个OFDM符号。换言之，同步信号的时域资源可以包括一个OFDM符号，或者同步信号的时域资源可以包括多个OFDM符号。其中，同步信号的时域资源可以包括同步信号的时间长度和同步信号的时域位置。其中，同步信号的时域位置包括同步信号的时域起始位置和/或同步信号的时域结束位置。
示例性的，如图12所示，为同步信号的时域资源包括一个OFDM符号示意图。其中，同步信号的时域资源包括一个子帧内的OFDM符号#1。同步信号的时域起始位置为该子帧内OFDM符号#1的时域起始位置，同步信号的时域结束位置为该子帧内OFDM符号#1的时域结束位置，同步信号的时间长度为OFDM符号#1的时间长度(即1个OFDM符号)。
示例性的，如图13所示，为同步信号的时域资源包括一个子帧内两个OFDM符号的示意图。其中，同步信号的时域资源包括OFDM符号#1和OFDM符号#2。同步信号的时域起始位置为该子帧内OFDM符号#1的时域起始位置，同步信号的时域结束位置为该子帧内OFDM符号#2的时域结束位置，同步信号的时间长度为OFDM符号#1的时间长度与OFDM符号#2的时间长度之和(即2个OFDM符号)。
如具体实施方式相关技术介绍部分所述，本申请实施例中，同步信号位于第一设备发送的下行数据之前，以用于第二设备确定下行数据的时域起始位置。示例性的，如图14所示，为本申请实施例提供的一种同步信号的时域资源的示意图。其中，同步信号可以与下行数据相邻。也就是说，当第二设备接收到同步信号之后，可以通过同步信号确定下行数据的时域起始位置。
可选地，本申请实施例中，同步信号的OFDM时域信号之前或之后可以添加保护间隔(guard interval,GI)。其中，GI可以是CP。
需要说明，如图15所示，为本申请实施例提供的一种OFDM符号的结构示意图，在OFDM时域信号之前或之后添加GI的情况下，一个OFDM符号包括两部分：GI和有用信号(payload)。其中，有用信号为OFDM频域信号进行IFFT之后的OFDM符号。换言之，一个OFDM符号中的有用信号为用于传输“序列”或“数据”或“信息”的部分。
可以理解，一个OFDM符号的时间长度为GI的时间长度TGI与有用信号的时间长度Tpayload之和。
需要说明，“有用信号”还可以替换表述为“数据”，“序列”，“有用数据”，“负载”，“有用负载”，“载荷”，以及“有效载荷”等，在此统一说明，以下不再赘述。
此外，“传输”与“承载”含义相同。换言之，“传输”与“承载”可以相互替换表述，在此统一说明，以下不再赘述。
可以理解，有用信号的时间长度Tpayload与IFFT的采样频率和采样点数有关。换言之，有用信号的时间长度Tpayload可以由采样频率和采样点数表征。相应地，GI的时间长度TGI也可以由采样频率和采样点数表征。
可选地，在本申请实施例中，同步信号可以包括第一信号(也可以称之为Delimiter)。 其中，第一信号用于确定第一设备向第二设备发送的数据(下行数据)所占用的时域起始位置。也就是说，可以通过同步信号中的第一信号确定下行数据的时域起始位置。
可选地，基于唤醒机制的通信系统中，同步信号可以包括第一信号(也可以称之为Delimiter)。其中，第一信号用于确定第一设备向第二设备发送的数据(下行数据)所占用的时域起始位置。也就是说，第二设备可以通过同步信号中的第一信号确定下行数据的时域起始位置。其中，该下行数据可以包括前导码和唤醒信号。前导码可以为一个序列，该序列由“0”和“1”组成。唤醒信号可以用于指示第二设备的标识。或者，唤醒信号可以用于指示第二设备所在的终端设备组的标识。或者，唤醒信号可以用于指示第二设备的标识的一部分。或者，唤醒信号可以用于指示第二设备所在的终端设备组的标识。
可选地，在本申请实施例中，第一信号可以用于唤醒第二设备。也就是说，第二设备在接收来自第一设备的第一信号之后，第二设备的计数器开始工作，开始检测接收的信号的时间长度，以接收并解调下行数据。换言之，第二设备在接收第一信号之前，第二设备的计数器不工作，可以不检测接收的信号的时间长度，以达到节能的效果。
示例性的，如图16所示，为本申请实施例提供的另一种同步信号的时域资源的示意图。其中，在同步信号之前，第一设备发送的是载波信号。载波信号用于为第二设备提供能量，即载波信号为高电平信号。相应地，第一信号可以是低电平信号。也就是说，第二设备在载波信号之后接收到低电平的第一信号，可以确定开始接收下行数据。
可选地，在本申请实施例中，同步信号可以包括第二信号(也可以称之为校准信号)。其中，第二信号用于确定第二设备向第一设备发送的数据的频率。示例性的，第二设备向第一设备发送的数据的频率可以是BLF；进而，第二设备可以利用公式(1)确定BLF。
可以理解，本申请实施例中，第一信号可以实现的功能可以包括前序部分帧头中的定界符所实现的功能，第二信号可以实现的功能可以包括前序部分帧头中的TRcal所实现的功能。
一种可能的实现方式中，同步信号仅包括第一信号。如上所述，同步信号的时域资源包括一个或多个OFDM符号，由此在同步信号仅包括第一信号的情况下，第一信号的时间长度可以是一个或多个OFDM符号的时间长度。
示例性的，同步信号仅包括第一信号的场景例如可以是：第一设备向第二设备发送除查询命令之外的下行信令。此时，由于查询命令之外的下行信令不包括DR，不需要第二设备计算BLF，进而同步信号可以仅包括第一信号。或者，在第二设备已经确定BLF的情况下，同步信号可以仅包括第一信号。
或者，在另一种可能的实现方式中，同步信号包括第一信号和填充数据。也就是说，在第一信号的时间长度小于一个OFDM符号的时间长度的情况下，或者在第一信号的时间长度小于同步信号的时间长度的情况下，可以通过填充数据的方式，使得同步信号的时间长度为一个或多个OFDM符号的时间长度。其中，填充数据可以是无效数据，或者无用数据。
或者，在另一种可能的实现的方式中，同步信号包括第一信号和第二信号。也就是说，第二设备根据同步信号可以确定下行数据的时域起始位置和BLF。
示例性的，同步信号包括第一信号和第二信号的场景例如可以是：第一设备发送的下行信令为查询命令，其中查询命令中携带DR。此时，第二设备可以根据第一信号确定下行数据的时域起始位置，之后可以获得第二信号和查询命令中的DR，进而第二设备可以根据第二信号的时间长度，DR，以及公式(1)，计算得到BLF。
S1102、第一设备向第二设备发送同步信号。相应地，第二设备接收来自第一设备的同步信号。
S1103、第二设备根据同步信号进行时间同步和/或频率同步。
也就是说，第二设备可以根据同步信号中的第一信号确定下行数据所占用的时域起始位置，以及根据同步信号中的第二信号确定BLF。
由于本申请实施例中，同步信号是通过OFDM的方式生成的，使得同步信号与传输下行数据的OFDM子载波之间彼此正交，进而第二设备解调信号时可以将同步信号的时域波形与传输下行数据的OFDM子载波的时域波形完全分离，避免干扰。因此，在NR系统引入Passive IoT或者ambient power-enabled IoT等低功耗通信系统的情况下，可以使得低功耗通信系统的同步信号与NR系统的子载波共存。
其中，本申请实施例中，在第一设备为接入网设备的情况下，上述步骤S1101至S1103中的第一设备的动作可以由图10所示的接入网设备1010中的处理器1011调用存储器1012中存储的应用程序代码以指令该接入网设备执行；在第一设备为终端设备的情况下，上述步骤S1101至S1103中的第一设备的动作可以由图10所示的终端设备1000中的处理器1001调用存储器1002中存储的应用程序代码以指令该终端设备执行，本实施例对此不作任何限制。
其中，本申请实施例中，在第二设备为终端设备的情况下，上述步骤S1101至S1103中的第二设备的动作可以由图10所示的终端设备1000中的处理器1001调用存储器1002中存储的应用程序代码以指令该终端设备执行，本实施例对此不作任何限制。
可选地，本申请实施例中，第二信号位于第一信号之后。也就是说，第二设备检测到第一信号之后，第二设备可以检测到第二信号，获取第二信号的时间长度，进而结合下行数据中携带的DR，可以计算BLF。
可选地，在一种可能的实现方式中，第一信号与第二信号位于不同的OFDM符号。
可选地，第一信号占用的OFDM符号与第二信号占用的OFDM符号之间的时间间隔是预定义的。也就是说，第二设备检测到第一信号之后，可以确定第二信号占用的OFDM符号。
需要说明，第一信号占用的OFDM符号与第二信号占用的OFDM符号之间的时间间隔可以是第一设备与第二设备提前协商好的；或者，预先在第二设备上配置第一信号占用的OFDM符号与第二信号占用的OFDM符号之间的时间间隔；或者，协议约定第一信号占用的OFDM符号与第二信号占用的OFDM符号之间的时间间隔，本申请实施例对此不作具体限定。
示例性的，以第一信号占用的OFDM符号与第二信号占用的OFDM符号之间的时间间隔为0为例，如图17所示，第一信号与第二信号位于两个相邻的OFDM符号 内。也就是说，第二设备检测到第一信号之后，可以确定第一信号之后的OFDM符号承载第二信号。
示例性的，以第一信号占用的OFDM符号与第二信号占用的OFDM符号之间的时间间隔为T个OFDM符号为例，其中T为正整数，第一信号占用的OFDM符号与第二信号占用的OFDM符号之间间隔T个OFDM符号。也就是说，第二设备检测到第一信号之后，可以在T个OFDM符号之后开始接收第二信号。
可选地，在另一种可能的实现方式中，第一信号与第二信号位于同一个OFDM符号内。也就是说，第二设备检测到第一信号之后，可以确定开始接收第二信号。
示例性的，图18示例出了第一信号与第二信号位于同一个OFDM符号内的同步信号的结构示意图。其中，第二信号可以与第一信号相邻。第二信号的时间长度与第一信号的时间长度之和可以为一个OFDM符号的时间长度，或者第二信号的时间长度与第一信号的时间长度之和可以小于一个OFDM符号的时间长度，本申请实施例对此不作具体限定。
需要说明，上述同步信号还可以包括其他的符号，比如前序部分的数据0，以及RTcal等。
可选地，本申请实施例中，第一信号与第二信号之间的时间间隔为预定义的。也就是说，第二设备检测到第一信号之后，可以确定第二信号的时域起始位置。
需要说明，第一信号与第二信号的时间间隔可以是第一设备与第二设备提前协商好的；或者，预先在第二设备上配置第一信号与第二信号的时间间隔；或者，协议约定第一信号与第二信号的时间间隔，本申请实施例对此不作具体限定。
下面分为两种生成同步信号的时域波形的方式，对步骤S1101进行详细阐述。
方式一：同步信号的波形可以是使用循环前缀的正交频分复用波形(conventional OFDM using a Cyclic Prefix,CP-OFDM)。也就是说，同步信号所占用的OFDM符号包括两部分：CP和有用信号。进而，一个OFDM符号的时间长度为CP的时间长度TCP与有用信号的时间长度Tpayload之和。
如前序部分所述，CP的时间长度TCP满足其中可以通过公式(2)得到。相应地，有用信号的时间长度Tpayload也可以由常数κ，子载波间隔配置μ和时间单位Tc表示，如公式(3)所示：
Z＝2048κ·2-μ·Tc       公式(3)
其中，Z可以用于表示有用信号的时间长度Tpayload。
示例性的，结合图9所示的通信系统900，说明第一设备发送的同步信号的波形为CP-OFDM波形的场景：在通信系统900中，接入网设备#1可以直接向终端设备#1～终端设备#6发送数据，因此接入网设备#1可以是第一设备，终端设备#1～终端设备#6可以是第二设备。此时，第一设备发送的同步信号是NR系统中下行链路传输的信号，而NR系统中下行链路传输的波形是CP-OFDM波形。进而，同步信号的波形可以是使用循环前缀的正交频分复用波形(The downlink transmission waveform is conventional OFDM using a Cyclic Prefix)。
可选地，在一种可能的实现方式中，同步信号的波形是基于第一序列，通过CP-OFDM的方式生成的。其中，第一序列可以是预定义的序列。
可选地，第一序列可以包括多个元素。
其中，每个元素可以用二进制符号“0”或“1”表示。
或者，每个元素可以是复数，可以用a+bj表示，j2＝-1，a和b为实数。
示例性的，第一序列可以由k个星座点组成。星座点可以为ASK的星座点，相移键控(phase-shift keying,PSK)的星座点，以及正交幅度调制(quadrature amplitude modulation,QAM)的星座点。其中ASK，PSK，以及QAM的调制阶数，本申请实施例不作具体限定。
需要说明，第一序列可以是预先在第一设备上存储或配置的；或者，协议约定第一序列，本申请实施例对此不作具体限定。
示例性的，如图19所示，为本申请实施例提供的同步信号的波形生成方式的模块框架示意图。其中，同步信号可以通过对第一序列进行子载波映射，将第一序列映射到子载波上，之后进行IFFT，并添加CP，进而生成同步信号的波形。其中，CP可以添加在有用信号之前。
方式二：同步信号的波形是CP-OFDM波形，且通过(discrete fourier transform,DFT)变换预编码的方式生成的。也就是说，相对于方式一，方式二中增加了DFT操作实现时域至频域的转换。进而，第一设备发送的同步信号是时域信号,从而可以避免发送频域的OFDM信号所带来的较高峰均功率比(peak to average power ratio,PAPR)的问题。
可选地，本申请实施例中，同步信号的波形是CP-OFDM波形，且通过DFT扩频的变换预编码的方式生成的。或者，同步信号的波形是CP-OFDM波形，且同步信号的波形具有执行DFT扩展的变换预编码功能。
需要说明，“扩频”与“扩展”含义相同。换言之，“扩频”与“扩展”可以相互替换表述，在此统一说明，以下不再赘述。
此外，方式二对应的OFDM方式还可以称为离散傅里叶变换扩展正交频分复用(discrete fourier transform-spread OFDM,DFT-S-OFDM)。
示例性的，结合图9所示的通信系统920，说明同步信号的波形为DFT-S-OFDM波形的场景：在通信系统920中，终端设备#4可以直接向终端设备#5和/或终端设备#6发送数据，因此终端设备#4可以是第一设备，终端设备#5或终端设备#6可以是第二设备。其中，终端设备发送数据的通信链路可以是NR系统中的上行链路。因此，第一设备发送的同步信号的波形可以是NR系统中上行链路传输的波形，而NR系统中上行链路传输的波形是DFT-S-OFDM波形。进而，同步信号的波形采用DFT-S-OFDM波形(The downlink transmission waveform is conventional OFDM using a CP with a transform precoding function performing DFT spreading)。
可选地，本申请实施例中，同步信号的波形是DFT变换预编码的方式生成的，包括：同步信号的波形是第二序列经过CP-OFDM后得到的波形。其中，第二序列为第一序列进行DFT扩频变换预编码后得到的序列。
示例性的，如图20所示，为本申请实施例提供的另一种同步信号的波形生成方式的模块框架示意图。其中，同步信号可以通过对第一序列进行DFT，得到第二序列，对第二序列进行子载波映射，之后进行IFFT，并添加CP，进而生成同步信号的波形。
下面对第一信号的时域位置和时间长度进行进一步阐述。
可选地，本申请实施例中，第一信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的前K个时间单元，K为正整数。也就是说，第一信号的时域资源包括OFDM符号中有用信号的起始部分，进而第二设备可以在第二信号和下行数据之前首先检测到第一信号，以便于后续下行数据或第二信号的接收。并且，在K小于N的情况下，第一信号仅占用OFDM符号的部分时域资源，因此可以利用OFDM符号中空闲的时域资源传输其他内容，比如第二信号，数据0，或者RTcal等，可以提高OFDM符号的时域资源的利用率。
示例性的，如图21所示，为本申请实施例提供的第一信号的时域资源示意图。其中，有用信号的时间长度为N个时间单元，第一信号的时域资源包括N个时间单元中的前K个时间单元。也就是说，第一信号的时域结束位置为N个时间单元中的第K个时间单元，以及第一信号的时间长度大于或等于K个时间单元。其中，K可以等于N。
或者，可选地，本申请实施例，第一信号的时域资源可以包括正整数个OFDM符号对应的时域单元。该正整数个OFDM符号用于承载第一信号。其中，OFDM符号对应的时域单元可以是指一个OFDM符号的时间长度。
可选地，本申请实施例中，时间单元可以是常数κ，或时间单位Tc，或时间单位Ts，或IFFT的预设采样点，或IFFT的预设采样频率，或子载波间隔等。
需要说明，“IFFT中的预设采样点”与“IFFT中的采样点”含义相同。换言之，“IFFT中的预设采样点”与“IFFT中的采样点”可以相互替换表述，在此统一说明，以下不再赘述。
下面结合信号的时域波形，对第一信号的时间长度进行进一步说明。
可选地，在本申请实施例中，第二设备在接收来自第一设备的第一信号之前，可以检测接收的信号的时间长度。也就是说，第二设备可以通过检测接收的信号的时间长度，并和第一信号的时间长度进行比较，来判断接收的信号是否为第一信号。
可选地，在本申请实施例中，第一信号为低电平信号。也就是说，第二设备检测到大于或等于第一信号的时间长度的低电平信号，可以确定检测到第一信号。
或者，可选地，在本申请实施例中，第一信号对应的时域波形的幅度小于第三阈值。或者，第一信号对应的时域波形的幅度的绝对值小于第四阈值。或者，第一信号对应的时域波形的幅度的最大值小于第五阈值。
或者，可选地，第一信号对应的时域波形的幅度的平均值小于第六阈值。
相应地，第二设备接收信号之后，可以计算接收信号的时域波形的幅度的平均值。也就是说，若平均值小于第六阈值，第二设备确定接收的信号为第一信号。
需要说明的是，第三阈值～第六阈值可以是预定义的。第三阈值～第六阈值之间可以相等或不相等。以第三阈值和第五阈值为例，第三阈值可以小于第五阈值，或者第三阈值等于第五阈值，或者第三阈值大于第五阈值。
此外，本申请实施例不对第三阈值～第六阈值的数值作具体限定。
示例性的，第一信号为低电平的场景例如可以是：图16所示的第一设备通过载波信号为第二设备提供能量的场景。可以理解，由于载波信号为第二设备供能，因此载波信号为高电平信号。这样，在第二设备接收到低电平的第一信号的情况下，第二设 备可以确定开始接收下行数据。
可选地，在一种可能的实现方式中，第一信号的时域资源还包括第一信号所在的OFDM符号中CP对应的部分时间单元。其中，CP的信号的电平与第一信号的电平相同。也就是说，在第一信号为低电平的情况下，通过在第一信号的时域资源增加CP对应的部分时间单元，使得低电平信号的持续时间足够长，进而第一信号可以与第二信号的低电平部分和/或下行数据的低电平部分之间区分。如此，第二设备接收到的信号时，可以确定接收信号中时间长度最长的低电平信号为第一信号。
示例性的，以图22所示的下行信号的结构示意图说明第二设备确定检测到第一信号。其中，第一信号的时间长度大于下行数据中低电平部分的时间长度，且大于第二信号中低电平部分的时间长度。进而，第二设备接收下行信号时，可以确定时间长度最长的低电平信号为第一信号。
相应地，对应上述方式二中使用DFT的方式生成同步信号的情况，第一序列中用于生成第二信号的第三序列中连续0符号(低电平)的个数小于第一序列中用于生成第一信号的第四序列中连续0符号(低电平)的个数。
示例性的，以第一序列为[000111100110]为例。其中，第一序列中前三个元素为第四序列[000]，第三序列可以为第一序列中除去[000]的部分[111100110]。进而，第三序列中连续0符号的个数(2个)小于第四序列中连续0符号的个数(3个)。可选地，一个OFDM的CP可以是通过复制一个OFDM符号中有用信号对应的N个时间单元中后S1个时间单元上承载的信号得到的。其中，后S1个时间单元的时间长度等于该OFDM符号中CP的时间长度。
可选地，在本申请实施例中，第一信号所在的OFDM符号中有用信号对应的N个时间单元中后S个时间单元上承载的信号为低电平信号。其中，后S个时间单元的时间长度大于或等于第一信号所在的OFDM符号中CP的时间长度。也就是说，第一信号所在的OFDM符号中有用信号对应的后S个时间单元上承载的信号为低电平信号，可以确保CP的信号的电平为低电平。如此，可以增加第一信号的低电平部分的持续时间。
可选地，在本申请实施例中，第一序列的最后一个元素为0。换言之，第一序列以0结尾。比如，第一序列为[000111100110]，该序列的最后一个元素为0。
或者，可选地，第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号的时域波形的幅度小于第三阈值。
或者，可选地，第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号的时域波形的幅度的绝对值小于第四阈值。
或者，可选地，第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号的时域波形的幅度的最大值小于第五阈值。
或者，可选地，第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号的时域波形的幅度的平均值小于第六阈值。
可选地，在一种可能的实现方式中，第三阈值～第六阈值可以小于或等于第一信号所在的OFDM符号中有用信号的幅度的平均值。
可选地，在同步信号的波形是基于第一序列且通过CP-OFDM的方式生成的实施 例中，第一序列包括Q个元素，Q个元素中最后P个元素为表示低电平的第一符号。
示例性的，在第一序列的每个元素使用符号0或1表示的情况下，第一符号可以是符号0。
下面结合第二设备检测第一信号的角度，对第一信号的时间长度进行进一步说明。
可选地，在本申请实施例中，第一信号的时间长度为预定义的。也就是说，对于第二设备而言，第一信号的时间长度是已知，若第二设备在该已知的时间长度内检测到低电平信号，即可以确定检测到第一信号。这样可以提高第二设备检测第一信号的效率和/或降低第二设备检测第一信号的复杂度。
需要说明，第一信号的时间长度可以是预先在第二设备上存储或配置的；或者，协议约定第一信号的时间长度，本申请实施例对此不作具体限定。
可选地，第一信号的时间长度可以随第一信号所在时域资源不同而发生变化。换言之，第一信号的时间长度可以随发送第一信号的时域资源不同而变化。
为便于理解，从子载波间隔和CP类型两方面，说明第一信号的时间长度随时域资源的变化情况。
如上述公式(3)所示，有用信号的时间长度Tpayload的值为Z，而Tpayload的值还等于上述N个时间单元，其中Z由常数κ和子载波间隔配置μ表示，即在子载波间隔配置不同的情况下，Z值不同。因此，时间单元的数值随子载波间隔配置的不同而发生变化，进而K个时间单元的时间长度也随子载波间隔配置的不同而发生变化。换言之，在子载波间隔配置不同的情况下，第一信号的时间长度(包括K个时间单元)不同。其中，在子载波间隔配置的值越大，时间单元的值越小，进而第一信号中K个时间单元的时间长度越小。
需要说明，在第一信号的时域资源包括第一信号所在的OFDM符号的CP的情况下，即使子载波间隔配置相同，第一信号的时间长度也可能不同。示例如下：如前序部分所述，相同子载波间隔配置下，CP类型可能不同。例如，子载波间隔配置μ为2时，子载波间隔Δf为60kHz，CP为normal CP或extended CP，可以通过信令配置确定在μ为2时，使用normal CP或extended CP。而normal CP对应的时间长度与extended CP对应的时间长度不同。
进一步的，不同OFDM符号对应的CP的时间长度可能不同。如图23所示，为本申请实施例提供的NR系统一个时隙内每个OFDM符号的时间长度示意图。其中，如公式(2)所述，对于normal CP，OFDM符号#0的CP的时间长度和OFDM符号#7的CP的时间长度大于其他编号的OFDM符号的CP的时间长度。
也就是说，在第一信号的时域资源包括第一信号所在的OFDM符号的CP的情况下，即使相同的子载波配置，第一信号的时间长度随CP类型的不同而发生变化。换言之，第一信号的时间长度随OFDM符号的位置的变化而不同。
为表述方便，本申请实施例中，对于normal CP，将OFDM符号#0的CP和OFDM符号#7的CP表述为“长CP(long CP)”，将其他编号的OFDM符号的CP表述为“短CP(short CP)”。
可选地，在本申请实施例中，第一信号所在的OFDM符号的CP的时间长度是固定。也就是说，在相同的子载波间隔配置下，第二设备接收第一信号时不需要盲检不 同时间长度的第一信号，可以提高第二设备检测第一信号的效率和/或降低第二设备检测第一信号的复杂度。
可选地，在一种可能的实现方式中，第一信号所在的OFDM符号为包含normal CP中短CP的OFDM符号。也就是说，第一信号所在的OFDM符号的CP的时间长度为公式(2)中的144κ·2-μ·Tc。进而，在相同的子载波间隔配置下，第一信号的时间长度为固定值。
或者，可选地，第一信号所在的OFDM符号的编号满足l≠0或者l≠7·2μ。也就是说，第一信号所在的OFDM符号的CP的时间长度为公式(2)中的144κ·2-μ·Tc。
可选地，在另一种可能的实现方式中，第一信号所在的OFDM符号为包含normal CP中长CP的OFDM符号。也就是说，第一信号所在的OFDM符号的CP的时间长度为公式(2)中的(144κ·2-μ+16κ)·Tc。进而，在相同的子载波间隔配置下，第一信号的时间长度为固定值。
或者，可选地，第一信号所在的OFDM符号的编号满足l＝0或者l＝7·2μ。也就是说，第一信号所在的OFDM符号的CP的时间长度为公式(2)中的(144κ·2-μ+16κ)·Tc。
可选地，在另一种可能的实现方式中，第一信号所在的OFDM符号为包含extend CP的OFDM符号。也就是说，第一信号所在的OFDM符号的CP的时间长度为公式(2)中的512κ·2-μ·Tc。进而，在相同的子载波间隔配置下，第一信号的时间长度为固定值。
或者，可选地，在本申请实施例中，第一信号的子载波间隔为60kHz。或者，第一信号的子载波间隔配置μ为2。也就是说，第一信号所在的OFDM符号的CP的时间长度为公式(2)中的512κ·2-μ·Tc。
下面从第一设备发送第一信号的时域资源利用率的角度，进一步说明第一信号的时间长度。
可选地，在本申请实施例中，第一信号的时间长度大于或等于第一阈值且小于或等于第二阈值。其中，第一阈值大于或等于TLCP+t·Z，TLCP为长CP的时间长度，Z为有用信号的时间长度Tpayload，t为系数，第二阈值小于或等于TSCP+t·Z，TSCP为短CP的时间长度。也就是说，第一信号的时间长度可以小范围内变化，进而第一设备可以在任意时域位置发送第一信号。换言之，第一设备不必在特定的时域资源上发送第一信号，可以提高时域资源的利用率。
需要说明，t可以取值为1，1/2，1/4，或者1/5等，本申请实施例对此不作具体限定。
为方便理解，结合前序部分的NR系统参数对第一阈值和第二阈值进行说明。
如图24所示，为本申请实施例提供的第一阈值与第二阈值取值范围示意图。其中，第一阈值为X+Y，第二阈值为X-Y，X＝t·Z+(TLCP+TSCP)/2，Y≥(TLCP-TSCP)/2。可以理解，在本申请实施例中，Z＝2048κ·2-μ·Tc，TLCP＝(144κ·2-μ+16κ)·Tc，TSCP＝144κ·2-μ·Tc。将这些参数代入到X与Y中，可以得到X(2048κ·2-μ+144κ·2-μ+8κ)·Tc＝(2192κ·2-μ+8κ)·Tc，Y≥8κ·Tc。
可选地，在本申请实施例中，第二设备在[X-Y,X+Y]的时间范围内检测到低电平 信号的情况下，第二设备确定检测到第一信号。
下面结合生成同步信号的OFDM方式，对本申请实施例中的第二信号的时域资源进行进一步阐述。
可选地，在本申请实施例中，第二信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的M个时间单元，M为正整数。由于生成OFDM符号的过程中需要IFFT，而IFFT采样是取整数的，若第二信号的时域资源包括的M个时间单元中的M不是正整数，那么经过IFFT之后，不是整数的部分会被量化为整数，因此会引入误差。也就是说，在通过OFDM生成第二信号的过程中，M为正整数，可以减少在IFFT预设采样率下量化引入的误差。
示例性的，如图25所示，为本申请实施例提供的第二信号的时域资源示意图。其中，有用信号的时间长度为N个时间单元，第二信号的时域资源包括N个时间单元中的M个时间单元。
需要说明，M个时间单元为连续的M个时间单元。
可选地，本申请实施例中，时间单元可以为常数κ，或时间单位Tc，或时间单位Ts，或IFFT的预设的采样点，或IFFT的预设采样频率，或子载波间隔等。
可选地，在本申请实施例中，同步信号包括第二信号。其中，同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的。第一序列包括第三序列。第三序列为用于生成第二信号的序列。
其中，M满足第一条件，第一条件包括：
N为M的L倍，且第一序列包含的元素个数为第三序列包含的元素个数的L倍，其中，N为2的幂次方，L为正整数。
下面结合图26所示的下行信号的时域资源示意图，说明第二信号的时域资源。
示例性的，如图26所示，为本申请实施例提供的一个下行信号的时域资源示意图。其中，下行信号包括载波信号，同步信号和下行数据。在同步信号之前的OFDM符号#0内发送的是载波信号，载波信号用于为第二设备提供能量，载波信号为高电平。载波信号之后的OFDM符号#1承载的是同步信号，同步信号之后的OFDM符号#2内承载的是下行数据。
其中，同步信号包括第一信号和第二信号，同步信号的子载波间隔为15kHz，第一信号的时间长度为21.6μs+/-2％，即容差范围2％。也就是说，考虑了不同OFDM符号的CP长度，同步信号可以在任何一个OFDM符号发送。进而，同步信号的时域资源配置灵活，利用率高。
其中，在采样率为1.92MHz时，一个OFDM符号的采样点数为128，即一个OFDM符号的有用信号对应128个时间单元。相应地，对应上述方式二中使用DFT的方式生成同步信号的情况，第一序列可以为[000111100110]，第一序列的元素个数为12。其中，第二信号对应第一序列中的[111100]，即第三序列，第三序列的元素个数为6。进而，第一序列的元素个数为第三序列的元素个数的2倍，即L＝2。根据第一条件，M＝128/2＝64，这样第二信号在时域上的样点数M为整数，并且第二信号的长度为33.3μs。
需要说明，本申请实施例中，“时间单元”与进行OFDM后的“样点数”可以替 换表述，在此统一说明，以下不再赘述。
下面结合第二设备测量信号时间长度的方式，对第二信号的时间长度进行进一步说明。
可选地，在一种可能的实现方式中，第二设备通过计数器测量第二信号的时间长度。
需要说明，由于信号和时钟边界不是严格对齐的，计数器的计数误差范围在+/-1个时钟周期(clock cycle)。
示例性的，如图27所示，为第二设备通过计数器测量高电平部分的时间长度的示意图。其中，信号1的时间长度为3个时钟周期，信号1的边界和时钟边界是对齐的，因此信号1可以被准确计数为3个时钟周期。信号2的时间长度为2.5个时钟周期，信号2的边界和时钟边界是不对齐的，计数器只能进行整数计数，因此信号2被计数为3个时钟周期，引入误差。结合图27所示的测量信号时间长度的方式，可以得到第二设备测量信号时间长度的误差如公式(4)所示：
error＝|M1-M2|/M2       公式(4)
其中，error表示误差，M1表示第二设备测量信号时间长度的测量计数，M2表示信号时间长度的真实时钟实际时钟周期的真实计数。M2与M成正比。
可选地，在本申请实施例中，M为满足第一条件的多个数值中的最大值。也就是说，M值越大，第二设备测量第二信号时间长度的误差越小。
下面列举几个同步信号的结构和对应的第一序列，以进一步说明本申请实施例的同步信号。
示例一：同步信号包括第一信号。其中，生成该同步信号的第一序列可以为[000000000000]。或者，生成该同步信号的第一序列可以为[000110]。或者，生成该同步信号的第一序列可以为[001100]。
可选地，在一种可能的实现方式中，该同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的。其中，第一信号可以作为唤醒信号，该第一信号可以用于唤醒第二设备。也就是说，第二设备在接收来自第一设备的第一信号之后，第二设备的计数器开始工作，开始检测接收的信号的时间长度，以接收并解调下行数据。换言之，第二设备在接收第一信号之前，第二设备的计数器不工作，可以不检测接收的信号的时间长度，以达到节能的效果。
示例二：同步信号可以包括第一信号和第二信号。
可选地，生成该同步信号的第一序列可以为[0000000000001111001111100]。其中，第一信号可以对应第一序列中的[000000000000]，第二信号对应第一序列中的[111100]。或者，第二信号可以是对应第一序列中结束位置的[111100]；或者，第二信号也可以对应第一序列中不处于结束位置的[111100]。
或者，可选地，第一序列可以为[000000000000111111111100]。其中，第一信号对应第一序列中的[000000000000]，第二信号对应第一序列中的[111111111100]。
可选地，生成该同步信号的第一序列可以为[000110111100]。其中，第一信号可以对应第一序列中的[000110]，第二信号对应第一序列中的[111100]。
或者，可选地，第一序列可以为[001100111100]。其中，第一信号对应第一序列中 的[001100]，第二信号对应第一序列中的[111100]。
可选地，在一种可能的实现方式中，同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的。其中，第一信号可以作为唤醒信号，该第一信号可以用于唤醒第二设备。也就是说，第二设备在接收来自第一设备的第一信号之后，第二设备的计数器开始工作，开始检测接收的信号的时间长度，以接收并解调下行数据。换言之，第二设备在接收第一信号之前，第二设备的计数器不工作，可以不检测接收的信号的时间长度，以达到节能的效果。
可选地，在一种可能的实现方式中，第一设备发送第一信号的天线端口与发送第二信号的天线端口相同。
可选地，在一种可能的实现方式中，第二设备接收第一信号的天线端口与接收第二信号的天线端口相同。
可选地，在一种可能的实现方式中，第一信号所在的OFDM符号中CP的长度与第二信号所在的OFDM符号中CP的长度相同。
可选地，在一种可能的实现方式中，第一信号所在的OFDM符号的CP类型和第二信号所在的OFDM符号的CP类型相同。示例性的，第一信号所在的OFDM符号的CP类型和第二信号所在的OFDM符号的CP类型均为extended CP；或者，第一信号所在的OFDM符号的CP类型和第二信号所在的OFDM符号的CP类型均为normal CP。
可选地，在一种可能的实现方式中，第一信号的子载波间隔与第二信号的子载波间隔相同。
可选地，如图11所示，本申请实施例提供的同步方法还可以包括以下步骤：
S1104，第二设备向第一设备发送能力信息。相应地，第一设备接收来自第二设备的能力信息。也就是说，第二设备可以向第一设备上报能力信息。
可选地，能力信息可以包括以下一项或多项：第二设备是否支持能量收集，第二设备是否支持包络检波，或者第二设备是否支持反向散射通信。
用理解，第二设备支持能量收集可以是指第二设备支持从环境中自主地获取其它类型的能量(如太阳光能，温差热能，振动能量，风能，或者射频能量等)，并将其转化为电能。能量收集的好处是替代电池给设备供电或补充电池能量，从而延长设备使用寿命，通过能量收集的方式产生的能量可以提供给第二设备的信号处理或者数据存储电路，以维持第二设备正常的工作状态。
应理解，第二设备支持包络检波可以是指第二设备支持以包络检波的方式接收信号。该信号可以是来自第一设备的信号。
其中，包络检波可以是指将高频或中频的输入信号经过半波或者全波整流后得到低频原始信号的包络或者幅度线的一种信号检测方法。如此，第二设备以包括检波的方式接收信号之后可以得到原始信号的包络。进而，第二设备可以对原始信号的包络进行数字采样，并与第二设备设置的幅度或者能量门限进行比较，判决接收的信号是1还是0。当然，第二设备还可以根据其它实现方式判决接收的信号是1还是0，本申请实施例对此不作具体限定。
应理解，第二设备支持反向散射通信可以是指第二设备支持在没有主动发射的射 频链路的情况下可以向第一设备传递信息；或者，第二设备支持在自身具备主动发射的射频链路但不需要开启的情况下向第一设备传递信息。也就是说，第二设备此时主要依赖于第一设备之外的激励设备或第一设备发射的连续载波来进行调制。示例性的，第二设备可以通过调整第二设备的天线的阻抗来反射一部分或者全部入射的载波；或者，第二设备也可以通过调整第二设备的天线的阻抗来不反射入射的载波，或者吸收入射的载波的能量。如此，第二设备通过调节第二设备的天线的阻抗，可以实现将第二设备的数字信息调制到入射的载波上，并传递给第一设备。
可选地，本申请实施例中，第二设备支持的最大带宽受限。
可选地，一种可能的实现方式中，第二设备支持的最大上行带宽不超过X1。
示例性的，X1为20MHz，或者X1为5MHz，或者X1为3MHz，或者X1为1.4MHz，或者X1为1MHz，或者X1为720kHz，或者X1为540kHz，或者X1为360kHz，或者X1为180kHz。
或者，可选地，X1为K1个资源块，K1为正整数。
示例性的，K1为小于或等于11的正整数，或者K1为小于或等于25的正整数，或者K1为小于或等于51的正整数，或者K1为小于或等于106的正整数。
可选地，另一种可能的实现方式中，第二设备支持的最大下行带宽不超过Y1。
示例性的，Y1为20MHz，或者Y1为5MHz，或者Y1为3MHz，或者Y1为1.4MHz，或者Y1为1MHz，或者Y1为720kHz，或者Y1为540kHz，或者Y1为360kHz，或者Y1为180kHz。
或者，可选地，Y1为K2个资源块，K2为正整数。
示例性的，K2为小于或等于11的正整数，或者K2为小于或等于25的正整数，或者K2为小于或等于51的正整数，或者K2为小于或等于106的正整数。
可选地，本申请实施例中，第二设备支持的最大上行带宽小于或者等于第二设备支持的最大下行带宽。
可选地，本申请实施例中，第二设备支持的发送和/或接收天线数有限。
可选地，第二设备接收天线数不超过X2。其中，X2为1，或2，或4。
或者，可选地，第二设备的接收分支(Rx branch)数不超过X2，其中X2为1，或2，或4。
可选地，第二设备发送天线数不超过Y2。其中，Y2为1，或2，或4。
或者，可选地，第二设备的发送分支数不超过Y2。其中，Y2为1，或2，或4。
可选地，第二设备的发送天线数大于或等于第二设备的接收天线数。
或者，可选地，第二设备的发送分支数大于或等于第二设备的接收分支数。
需要说明的是，本申请实施例中，“接收分支”还可以称为“接收的射频通道数”，或者“接收的射频链(RF chain)数”。“发送分支”也可以称为“发送的射频通道数”，或者“发送的射频链数”。
需要说明的是，第二设备可以不在具有配对频谱(paired spectrum)的服务小区上同时发送和接收。
可以理解的是，以上各个实施例中，由第一设备实现的方法和/或步骤，也可以由可用于该第一设备的部件(例如处理器、芯片、芯片系统、电路、逻辑模块、或软件) 实现。由第二设备实现的方法和/或步骤，也可以由可用于该第二设备的部件(例如处理器、芯片、芯片系统、电路、逻辑模块、或软件)实现。
上述主要对本申请提供的方案进行了介绍。相应的，本申请还提供了通信装置，该通信装置用于实现上述方法实施例中的各种方法。该通信装置可以为上述方法实施例中的第一设备，或者包含第一设备的装置，或者为可用于第一设备的部件，例如芯片或芯片系统。或者，该通信装置可以为上述方法实施例中的第二设备，或者包含第二设备的装置，或者为可用于第二设备的部件，例如芯片或芯片系统。
可以理解的是，该通信装置为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本申请实施例可以根据上述方法实施例对通信装置进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。需要说明的是，本申请实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
以通信装置为上述方法实施例中的第一设备为例，图28示出了一种第一设备280的结构示意图。该第一设备280包括处理模块2801和收发模块2802。
在一些实施例中，该第一设备280还可以包括存储模块(图28中未示出)，用于存储程序指令和数据。
在一些实施例中，处理模块2801，用于生成同步信号。收发模块2802，用于向第二设备发送同步信号。其中，同步信号是通过OFDM的方式生成的，同步信号包括第一信号和/或第二信号，第一信号用于确定第一设备向第二设备发送的数据所占用的时域起始位置，第二信号用于确定第二设备向第一设备发送的数据的频率。
在一些实施例中，同步信号包括第一信号和第二信号，其中，第二信号位于第一信号之后。
在一些实施例中，第一信号与第二信号位于同一个OFDM符号内。
在一些实施例中，同步信号的波形是CP-OFDM波形。
在一些实施例中，同步信号的波形是基于第一序列，通过CP-OFDM的方式生成的。
在一些实施例中，同步信号的波形是通过DFT变换预编码的方式生成的。
在一些实施例中，同步信号的波形是通过DFT变换预编码的方式生成的，包括：同步信号的波形是第二序列经过CP-OFDM后得到的波形，其中，第二序列为第一序列进行DFT变换预编码后得到的序列。
在一些实施例中，第一信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的前K个时间单元，K为正整数，其中，一个OFDM符号中的有用信号为一个OFDM符号中承载有用信息或有用数据的部分。
在一些实施例中，第一信号的时域资源还包括第一信号所在的OFDM符号中CP对应的部分时间单元。
在一些实施例中，第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号为低电平信号，其中，后S个时间单元的时间长度大于或等于第一信号所在的OFDM符号中CP的时间长度，其中，一个OFDM符号中的有用信号为一个OFDM符号中承载有用信息或有用数据的部分。
在一些实施例中，第二信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的M个时间单元，M为正整数，其中，一个OFDM符号中的有用信号为一个OFDM符号中承载有用信息或有用数据的部分。
在一些实施例中，同步信号包括第二信号，其中，同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的，第一序列包括第三序列，第三序列为用于生成第二信号的序列；M满足第一条件，第一条件包括：
N为M的L倍，且第一序列包含的元素个数为第三序列包含的元素个数的L倍，其中，N为2的幂次方，L为正整数。
在一些实施例中，M为满足第一条件的多个数值中的最大值。
在一些实施例中，收发模块2802还用于接收来自第二设备的能力信息。其中，能力信息包括以下至少一项：第二设备是否支持能量收集，第二设备是否支持包络检波，或者第二设备是否支持反向散射通信。
其中，上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在本申请中，该第一设备280以采用集成的方式划分各个功能模块的形式来呈现。这里的“模块”可以指特定专用集成电路ASIC，电路，执行一个或多个软件或固件程序的处理器和存储器，集成逻辑电路，和/或其他可以提供上述功能的器件。
在一些实施例中，当第一设备280为接入网设备时，在硬件实现上，本领域的技术人员可以想到该第一设备280可以采用图10所示的接入网设备1010的形式。
作为一种示例，图28中的处理模块2801的功能/实现过程可以通过图10所示的接入网设备1010中的处理器1011调用存储器1012中存储的计算机执行指令来实现。图28中的收发模块2802的功能/实现过程可以通过图10所示的接入网设备1010中的收发器1013来实现。
在一些实施例中，当第一设备280为终端设备时，在硬件实现上，本领域的技术人员可以想到该第一设备280可以采用图10所示的终端设备1000的形式。
作为一种示例，图28中的处理模块2801的功能/实现过程可以通过图10所示的终端设备1000中的处理器1001调用存储器1002中存储的计算机执行指令来实现。图28中的收发模块2802的功能/实现过程可以通过图10所示的终端设备1000中的收发器1003来实现。
在一些实施例中，当图28中的第一设备280是芯片或芯片系统时，收发模块2802的功能/实现过程可以通过芯片或芯片系统的输入输出接口(或通信接口)实现，处理模块2801的功能/实现过程可以通过芯片或芯片系统的处理器(或者处理电路)实现。
由于本实施例提供的第一设备280可执行上述同步方法，因此其所能获得的技术 效果可参考上述方法实施例，在此不再赘述。
以通信装置为上述方法实施例中的第二设备为例，图29示出了一种第二设备290的结构示意图。该第二设备290包括处理模块2901和收发模块2902。
在一些实施例中，该第二设备290还可以包括存储模块(图29中未示出)，用于存储程序指令和数据。
在一些实施例中，收发模块2902，也可以称为收发单元用以实现发送和/或接收功能。该收发模块2902可以由收发电路，收发机，收发器或者通信接口构成。
在一些实施例中，收发模块2902，可以包括接收模块和发送模块，分别用于执行上述方法实施例中由第二设备执行的接收和发送类的步骤，和/或用于支持本文所描述的技术的其它过程；处理模块2901，可以用于执行上述方法实施例中由第二设备执行的处理类(例如确定等)的步骤，和/或用于支持本文所描述的技术的其它过程。例如：
收发模块2902，用于接收来自第一设备的同步信号。处理模块2901，用于根据同步信号进行时间同步和/或频率同步。其中，同步信号是通过OFDM的方式生成的，同步信号包括第一信号和/或第二信号，第一信号用于确定第一设备向第二设备发送的数据所占用的时域起始位置，第二信号用于确定第二设备向第一设备发送的数据的频率。
在一些实施例中，同步信号包括第一信号和第二信号，其中，第二信号位于第一信号之后。
在一些实施例中，第一信号与第二信号位于同一个OFDM符号内。
在一些实施例中，同步信号的波形是CP-OFDM波形。
在一些实施例中，同步信号的波形是基于第一序列，通过CP-OFDM的方式生成的。
在一些实施例中，同步信号的波形是通过DFT变换预编码的方式生成的。
在一些实施例中，同步信号的波形是通过DFT变换预编码的方式生成的，包括：同步信号的波形是第二序列经过CP-OFDM后得到的波形，其中，第二序列为第一序列进行DFT变换预编码后得到的序列。
在一些实施例中，第一信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的前K个时间单元，K为正整数，其中，一个OFDM符号中的有用信号为一个OFDM符号中承载有用信息或有用数据的部分。
在一些实施例中，第一信号的时域资源还包括第一信号所在的OFDM符号中CP对应的部分时间单元。
在一些实施例中，第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号为低电平信号，其中，后S个时间单元的时间长度大于或等于第一信号所在的OFDM符号中CP的时间长度，其中，一个OFDM符号中的有用信号为一个OFDM符号中承载有用信息或有用数据的部分。
在一些实施例中，第二信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的M个时间单元，M为正整数，其中，一个OFDM符号中的有用信号为一个OFDM符号中承载有用信息或有用数据的部分。
在一些实施例中，同步信号包括第二信号，其中，同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的，第一序列包括第三序列，第 三序列为用于生成第二信号的序列；M满足第一条件，第一条件包括：
N为M的L倍，且第一序列包含的元素个数为第三序列包含的元素个数的L倍，其中，N为2的幂次方，L为正整数。
在一些实施例中，M为满足第一条件的多个数值中的最大值。
在一些实施例中，收发模块2902还用于向第一设备发送能力信息。其中，能力信息包括以下至少一项：第二设备是否支持能量收集，第二设备是否支持包络检波，或者第二设备是否支持反向散射通信。
其中，上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在本申请中，该第二设备290以采用集成的方式划分各个功能模块的形式来呈现。这里的“模块”可以指特定专用集成电路ASIC，电路，执行一个或多个软件或固件程序的处理器和存储器，集成逻辑电路，和/或其他可以提供上述功能的器件。
在一些实施例中，当第二设备290为终端设备时，在硬件实现上，本领域的技术人员可以想到该第二设备290可以采用图10所示的终端设备1000的形式。
作为一种示例，图29中的处理模块2901的功能/实现过程可以通过图10所示的终端设备1000中的处理器1001调用存储器1002中存储的计算机执行指令来实现。图29中的收发模块2902的功能/实现过程可以通过图10所示的终端设备1000中的收发器1003来实现。
在一些实施例中，当图29中的第二设备290是芯片或芯片系统时，收发模块2902的功能/实现过程可以通过芯片或芯片系统的输入输出接口(或通信接口)实现，处理模块2901的功能/实现过程可以通过芯片或芯片系统的处理器(或者处理电路)实现。
由于本实施例提供的第二设备290可执行上述同步方法，因此其所能获得的技术效果可参考上述方法实施例，在此不再赘述。
在一些实施例中，本申请所述的第一设备或第二设备，还可以使用下述来实现：一个或多个现场可编程门阵列(field programmable gate array,FPGA)、可编程逻辑器件(programmable logic device,PLD)、控制器、状态机、门逻辑、分立硬件部件、任何其它适合的电路、或者能够执行本申请通篇所描述的各种功能的电路的任意组合。
在一些实施例中，本申请还提供一种通信装置，该通信装置包括处理器，用于实现上述任一方法实施例中的方法。
作为一种可能的实现方式，该通信装置还包括存储器。该存储器，用于保存必要的计算机程序和数据。该计算机程序可以包括指令，处理器可以调用存储器中存储的计算机程序中的指令以指令该通信装置执行上述任一方法实施例中的方法。当然，存储器也可以不在该通信装置中。
作为另一种可能的实现方式，该通信装置还包括接口电路，该接口电路为代码/数据读写接口电路，该接口电路用于接收计算机执行指令(计算机执行指令存储在存储器中，可能直接从存储器读取，或可能经过其他器件)并传输至该处理器。
作为又一种可能的实现方式，该通信装置还包括通信接口，该通信接口用于与该通信装置之外的模块通信。
可以理解的是，该通信装置可以是芯片或芯片系统，该通信装置是芯片系统时， 可以由芯片构成，也可以包含芯片和其他分立器件，本申请实施例对此不作具体限定。
本申请还提供了一种计算机可读存储介质，其上存储有计算机程序或指令，该计算机程序或指令被计算机执行时实现上述任一方法实施例的功能。
本申请还提供了一种计算机程序产品，该计算机程序产品被计算机执行时实现上述任一方法实施例的功能。
本领域普通技术人员可以理解，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
可以理解，本申请中描述的系统、装置和方法也可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，即可以位于一个地方，或者也可以分布到多个网络单元上。作为单元显示的部件可以是或者也可以不是物理单元。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件程序实现时，可以全部或部分地以计算机程序产品的形式来实现。该计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或者数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可以用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)，光介质(例如，DVD)、或者半导体介质(例如固态硬盘(solid state disk,SSD))等。本申请实施例中,计算机可以包括前面所述的装置。
尽管在此结合各实施例对本申请进行了描述，然而，在实施所要求保护的本申请过程中，本领域技术人员通过查看所述附图、公开内容、以及所附权利要求书，可理解并实现所述公开实施例的其他变化。在权利要求中，“包括”(comprising)一词不排除其他组成部分或步骤，“一”或“一个”不排除多个的情况。单个处理器或其他单元可以实现权利要求中列举的若干项功能。相互不同的从属权利要求中记载了某些措施，但这并不表示这些措施不能组合起来产生良好的效果。
尽管结合具体特征及其实施例对本申请进行了描述，显而易见的，在不脱离本申请的范围的情况下，可对其进行各种修改和组合。相应地，本说明书和附图仅仅是所附权利要求所界定的本申请的示例性说明，且视为已覆盖本申请范围内的任意和所有修改、变化、组合或等同物。显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (35)

  1. 一种同步方法，其特征在于，所述方法包括：
    第一设备生成同步信号，其中，所述同步信号是通过正交频分复用OFDM的方式生成的，所述同步信号包括第一信号和/或第二信号，所述第一信号用于确定所述第一设备向第二设备发送的数据所占用的时域起始位置，所述第二信号用于确定所述第二设备向所述第一设备发送的数据的频率；
    所述第一设备向所述第二设备发送所述同步信号。
  2. 根据权利要求1所述的方法，其特征在于，所述同步信号包括所述第一信号和所述第二信号，其中，所述第二信号位于所述第一信号之后。
  3. 根据权利要求2所述的方法，其特征在于，所述第一信号与所述第二信号位于同一个OFDM符号内。
  4. 根据权利要求1-3任一项所述的方法，其特征在于，所述同步信号的波形是使用循环前缀的正交频分复用CP-OFDM波形。
  5. 根据权利要求4所述的方法，其特征在于，所述同步信号的波形是基于第一序列，通过CP-OFDM的方式生成的。
  6. 根据权利要求4或5所述的方法，其特征在于，所述同步信号的波形是通过离散傅里叶变换DFT变换预编码的方式生成的。
  7. 根据权利要求6所述的方法，其特征在于，所述同步信号的波形是通过离散傅里叶变换DFT变换预编码的方式生成的，包括：
    所述同步信号的波形是第二序列经过CP-OFDM后得到的波形，其中，所述第二序列为第一序列进行DFT变换预编码后得到的序列。
  8. 根据权利要求1-7任一项所述的方法，其特征在于，所述第一信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的前K个时间单元，K为正整数，其中，所述一个OFDM符号中的有用信号为一个OFDM符号中除循环前缀CP之外的部分。
  9. 根据权利要求8所述的方法，其特征在于，所述第一信号的时域资源还包括所述第一信号所在的OFDM符号中CP对应的部分时间单元。
  10. 根据权利要求1-9任一项所述的方法，其特征在于，所述第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号为低电平信号，其中，所述后S个时间单元的时间长度大于或等于所述第一信号所在的OFDM符号中CP的时间长度，所述一个OFDM符号中的有用信号为一个OFDM符号中除CP之外的部分。
  11. 根据权利要求1-10任一项所述的方法，其特征在于，所述第二信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的M个时间单元，M为正整数，所述一个OFDM符号中的有用信号为一个OFDM符号中除CP之外的部分。
  12. 根据权利要求11所述的方法，其特征在于，所述同步信号包括所述第二信号，其中，所述同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的，所述第一序列包括第三序列，所述第三序列为用于生成所述第二信号的序列；M满足第一条件，所述第一条件包括：
    N为M的L倍，且所述第一序列包含的元素个数为所述第三序列包含的元素个数的L倍，其中，N为2的幂次方，L为正整数。
  13. 根据权利要求12所述的方法，其特征在于，M为满足所述第一条件的多个数值中的最大值。
  14. 一种同步方法，其特征在于，包括：
    第二设备接收来自第一设备的同步信号，所述同步信号是通过正交频分复用OFDM的方式生成的，所述同步信号包括第一信号和/或第二信号，所述第一信号用于确定所述第一设备向所述第二设备发送的数据所占用的起始位置，所述第二信号用于确定所述第二设备向所述第一设备发送的数据的频率；
    所述第二设备根据所述同步信号进行时间同步和/或频率同步。
  15. 根据权利要求14所述的方法，其特征在于，所述同步信号包括所述第一信号和所述第二信号，其中，所述第二信号位于所述第一信号之后。
  16. 根据权利要求15所述的方法，其特征在于，所述第一信号与所述第二信号位于同一个OFDM符号内。
  17. 根据权利要求14-16任一项所述的方法，其特征在于，所述同步信号的波形是使用循环前缀的正交频分复用CP-OFDM波形。
  18. 根据权利要求17所述的方法，其特征在于，所述同步信号的波形是基于第一序列，通过CP-OFDM的方式生成的。
  19. 根据权利要求17或18所述的方法，其特征在于，所述同步信号的波形是通过离散傅里叶变换DFT变换预编码的方式生成的。
  20. 根据权利要求19所述的方法，其特征在于，所述同步信号的波形是通过离散傅里叶变换DFT变换预编码的方式生成的，包括：
    所述同步信号的波形是第二序列经过CP-OFDM后得到的波形，其中，所述第二序列为第一序列进行DFT变换预编码后得到的序列。
  21. 根据权利要求14-20任一项所述的方法，其特征在于，所述第一信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的前K个时间单元，K为正整数，其中，所述一个OFDM符号中的有用信号为一个OFDM符号中除CP之外的部分。
  22. 根据权利要求21所述的方法，其特征在于，所述第一信号的时域资源还包括所述第一信号所在的OFDM符号中CP对应的部分时间单元。
  23. 根据权利要求14-22任一项所述的方法，其特征在于，所述第一信号所在的OFDM符号中有用信号对应的N个时间单元中的后S个时间单元上承载的信号为低电平信号，其中，所述后S个时间单元的时间长度大于或等于所述第一信号所在的OFDM符号中CP的时间长度，其中，所述一个OFDM符号中的有用信号为一个OFDM符号中除CP之外的部分。
  24. 根据权利要求14-23任一项所述的方法，其特征在于，所述第二信号的时域资源包括一个OFDM符号中有用信号对应的N个时间单元中的M个时间单元，M为正整数，其中，所述一个OFDM符号中的有用信号为一个OFDM符号中除CP之外的部分。
  25. 根据权利要求24所述的方法，其特征在于，所述同步信号包括所述第二信号，其中，所述同步信号的波形是对第一序列进行DFT变换预编码后，通过CP-OFDM的方式生成的，所述第一序列包括第三序列，所述第三序列为用于生成所述第二信号的序列；M满足第一条件，所述第一条件包括：
    N为M的L倍，且所述第一序列包含的元素个数为所述第三序列包含的元素个数的L倍，其中，N为2的幂次方，L为正整数。
  26. 根据权利要求25所述的方法，其特征在于，M为满足所述第一条件的多个数值中的最大值。
  27. 一种通信装置，其特征在于，所述通信装置用于执行如权利要求1-13中任一项所述的同步方法。
  28. 一种通信装置，其特征在于，所述通信装置用于执行如权利要求14-26中任一项所述的同步方法。
  29. 一种通信装置，其特征在于，包括：处理器，所述处理器与存储器耦合；
    所述处理器，用于执行所述存储器中存储的计算机程序，以使得所述通信装置执行如权利要求1-26中任一项所述的同步方法。
  30. 一种通信装置，其特征在于，包括：
    处理器和接口电路；其中，
    所述接口电路，用于接收代码指令并传输至所述处理器；
    所述处理器用于运行所述代码指令以执行如权利要求1-26中任一项所述的方法。
  31. 一种通信装置，其特征在于，所述通信装置包括处理器和收发器，所述收发器用于所述通信装置和其他通信装置之间进行信息交互，所述处理器执行程序指令，用以执行如权利要求1-26中任一项所述的同步方法。
  32. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质包括计算机程序或指令，当所述计算机程序或指令在计算机上运行时，使得所述计算机执行如权利要求1-26中任一项所述的同步方法。
  33. 一种计算机程序产品，其特征在于，所述计算机程序产品包括计算机程序或指令，当所述计算机程序或指令在计算机上运行时，使得所述计算机执行如权利要求1-26中任一项所述的同步方法。
  34. 一种同步方法，其特征在于，所述方法包括：
    第一设备生成同步信号，其中，所述同步信号是通过正交频分复用OFDM的方式生成的，所述同步信号包括第一信号和/或第二信号，所述第一信号用于确定所述第一设备向第二设备发送的数据所占用的时域起始位置，所述第二信号用于确定所述第二设备向所述第一设备发送的数据的频率；
    所述第一设备向所述第二设备发送所述同步信号；
    所述第二设备接收来自第一设备的同步信号；
    所述第二设备根据所述同步信号进行时间同步和/或频率同步。
  35. 一种通信系统，其特征在于，所述通信系统包括第一设备和第二设备，其中，所述第一设备用于执行如权利要求1-13中任一项所述的同步方法，所述第二设备用于指示执行如权利要求14-26中任一项所述的同步方法。
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