REFERENCE SIGNAL SENDING METHOD AND COMMUNICATION APPARATUS

This application provides a reference signal sending method and a communication apparatus. In the method, a time-domain cyclic shift factor is introduced, and phase rotation is performed on a first reference signal sequence jointly by using a frequency-domain cyclic shift factor and the time-domain cyclic shift factor, to obtain the second reference signal sequence. Because the time-domain cyclic shift factor is introduced, different transmit ends have at least one of different values of the frequency-domain cyclic shift factor and different values of the time-domain cyclic shift factor, that is, orthogonal multiplexing of second reference signal sequences of different transmit ends can be implemented, so that a capacity of second reference signal sequences is increased.

TECHNICAL FIELD

This application relates to the field of wireless communication technologies, and more specifically, to a reference signal sending method and a communication apparatus.

BACKGROUND

In a wireless communication system, a reference signal (RS) is a signal sent by a transmit end to a receive end. Because the signal is known to the receive end, communication system—related information or channel-related information, for example, a channel parameter, channel quality, or signal phase rotation caused by a device of the transmit end or the receive end, may be obtained by processing the reference signal received from the transmit end. A reference signal used to assist the receive end in performing channel estimation (CE) on a channel of the transmit end may also be referred to as a demodulation reference signal (DMRS). Usually, to accurately obtain communication system—related information and channel-related information of transmit ends or transmit ports of transmit ends, reference signals of different transmit ends or different transmit ports need to be orthogonal.

However, with continuous evolution of a communication system, a capacity of reference signals in many scenarios is continuously increased. For example, a quantity of antenna ports supported in multiple input-multiple output (MIMO) is continuously increased, and a communication system needs to support a larger quantity of orthogonal multiplexing reference signals, that is, a capacity of reference signals is increased. For another example, a carrier frequency is increased, and a requirement of some terminal devices (for example, a car or a high-speed railway) or in other mobile motion scenarios is increased. In these scenarios, a Doppler shift is increased as the carrier frequency or a moving speed is increased. In this case, a channel response of a transmit end changes rapidly. To accurately track the rapidly changing channel response by using a reference signal, a feasible method is to increase time domain density of reference signals. However, overheads of reference signals are also increased. In this case, it is more difficult to increase a capacity of reference signals.

However, a current capacity of reference signals can no longer meet an increasing requirement for a capacity of reference signals.

SUMMARY

This application provides a reference signal sending method and a communication apparatus, to increase a capacity of reference signal sequences.

According to a first aspect, this application provides a reference signal sequence sending method. The method includes: A transmit end obtains a frequency-domain cyclic shift factor and a time-domain cyclic shift factor, where the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are used to perform phase rotation on a reference signal sequence; generates a second reference signal sequence based on a first reference signal sequence, the frequency-domain cyclic shift factor, and the time-domain cyclic shift factor; and sends the second reference signal sequence on an antenna port p, where p∈{0, 1, P−1}, and P is an integer greater than or equal to 1.

In this technical solution of this application, the time-domain cyclic shift factor is introduced, and phase rotation is performed on the first reference signal sequence jointly by using the frequency-domain cyclic shift factor and the time-domain cyclic shift factor, to obtain the second reference signal sequence. Because the time-domain cyclic shift factor is introduced, different transmit ends have at least one of different values of the frequency-domain cyclic shift factor and different values of the time-domain cyclic shift factor, that is, orthogonal multiplexing of second reference signal sequences of different transmit ends can be implemented, so that a capacity of second reference signal sequences is increased.

In addition, in a high-speed moving scenario and/or a high-frequency scenario, a Doppler shift is significantly increased compared with that in a low-speed scenario and/or a low-frequency scenario, and overheads of reference signals need to be increased to quickly track a channel change. With this technical solution of this application applied to the high-speed moving scenario and/or the high-frequency scenario, time domain density of reference signals can be increased, so that a capacity of reference signals is increased when overheads of reference signals remain the same, or overheads of reference signals can be reduced when a capacity of reference signals remains the same.

With reference to the first aspect, in some implementations of the first aspect, the generating a second reference signal sequence based on a first reference signal sequence, the frequency-domain cyclic shift factor, and the time-domain cyclic shift factor includes:

generating Nrssecond reference signal sequences in a second reference signal sequence set based on the first reference signal sequence, the frequency-domain cyclic shift factor, and the time-domain cyclic shift factor, where the first reference signal sequence and each second reference signal sequence each include Mrselements, Nrs≥1 and is an integer, and Mrs>1 and is an integer; and performing phase rotation on an element m of the first reference signal sequence by using ej·αF·mand ej·αT·m, to obtain an element m of a second reference signal sequence tin the second reference signal sequence set, where 0≤m<Mrs, 0≤t<Nrs, αFis the frequency-domain cyclic shift factor, αTis the time-domain cyclic shift factor, j indicates an imaginary unit, and both m and t are integers.

Optionally, ej·αF·mmay be alternatively replaced with ej·αF·m, and ej·αT·mmay be alternatively replaced with ej·αT·m.

With reference to the first aspect, in some implementations of the first aspect, the sending the second reference signal sequence includes:

sending, in one resource unit, the Nrssecond reference signal sequences included in the second reference signal sequence set, where the resource unit includes N symbols in time domain, each symbol includes M subcarriers in frequency domain, the Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols, each second reference signal sequence is mapped to one of the N symbols, each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols, N≥Nrs, M≥Mrs, and both N and M are positive integers.

With reference to the first aspect, in some implementations of the first aspect, the resource unit includes one slot in time domain, the slot includes the N symbols, and each symbol includes the M subcarriers in frequency domain, where the Nrssymbols are arranged at equal intervals based on a first value width in the N symbols, and/or the Mrssubcarriers are arranged at equal intervals based on a second value width in the M subcarriers included in each symbol of the slot, where the first value width KTmeets the following formula: KT=N/Nrs, the second value width KFmeets the following formula: KF=M/Mrs, and KTand KFare positive integers.

The second reference signal sequences are configured to be arranged in a comb tooth form in time domain and in frequency domain, and a comb tooth size (for example, the first value width or the second value width) may be adjusted, so that density of reference signals (namely, second reference signal sequences) sent in one resource unit, that is, overheads of reference signals, can be flexibly adjusted, to meet requirements in different scenarios, for example, a low-speed scenario and a high-speed scenario.

With reference to the first aspect, in some implementations of the first aspect, the resource unit includes S slots in time domain, each slot includes N/S symbols, each symbol includes the M subcarriers in frequency domain, and N/S is an integer, where the Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols included in the S slots, and each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols.

A size of a resource unit is configured (for example, a quantity of slots included in one resource unit is configured), so that a quantity of slots in time domain that are used to send second reference signal sequences can be flexibly configured, to adapt to requirements in different scenarios. For example, if a large capacity of reference signals is required, one resource unit may be configured to include a larger quantity of slots, so that a value range of the time-domain cyclic shift factor αTis larger, and a larger quantity of orthogonal multiplexing reference signals are supported.

In addition, for different subcarrier spacings, one slot may be alternatively configured to include different quantities of symbols, to adjust a quantity of symbols in time domain that are used to send reference signals. For example, if a large capacity of reference signals is required, one slot may be configured, by using signaling, to include a larger quantity of symbols, so that a larger quantity of symbols are used to send reference signals, a value range of the time-domain cyclic shift factor αTis larger, and a larger quantity of orthogonal multiplexing reference signals are supported.

According to a second aspect, a reference signal sequence receiving method is provided. The method includes: A receive end obtains a frequency-domain cyclic shift factor and a time-domain cyclic shift factor, where the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are used to perform phase rotation on a reference signal sequence. The receive end receives a second reference signal sequence from an antenna port p of a transmit end, where p∈{0, 1, P−1}, and P is an integer greater than or equal to 1. The receive end demodulates the second reference signal sequence based on the frequency-domain cyclic shift factor and the time-domain cyclic shift factor.

Herein, that the receive end demodulates the second reference signal sequence is a process in which the receive end performs channel estimation to obtain a channel response. Further, the receive end performs, by using the channel response, processing such as equalization, demodulation, and decoding on data received from the transmit end, to obtain data sent by the transmit end.

With reference to the second aspect, in some implementations of the second aspect, that the receive end demodulates the second reference signal sequence based on the frequency-domain cyclic shift factor and the time-domain cyclic shift factor includes:

The receive end demodulates Nrssecond reference signal sequences in a second reference signal sequence set based on the frequency-domain cyclic shift factor and the time-domain cyclic shift factor, where an element m of a second reference signal sequence t in the second reference signal sequence set is obtained by performing phase rotation on an element m of a first reference signal sequence by using ej·αF·m, and ej·αT·m, the first reference signal sequence and each second reference signal sequence each include Mrselements, Nrs>1 and is an integer, Mrs>1 and is an integer, 0≤m<Mrs, 0≤t<Nrs, αFis the frequency-domain cyclic shift factor, αTis the time-domain cyclic shift factor, and j indicates an imaginary unit.

With reference to the second aspect, in some implementations of the second aspect, the receiving a second reference signal sequence from an antenna port p of a transmit end includes:

receiving the Nrssecond reference signal sequences that are included in the second reference signal sequence set in one resource unit and that come from the antenna port p of the transmit end, where the resource unit includes N symbols in time domain, each symbol includes M subcarriers in frequency domain, the Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols, each second reference signal sequence is mapped to one of the N symbols, each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols, N≥Nrs, M≥Mrs, and both N and M are positive integers.

With reference to the second aspect, in some implementations of the second aspect, the resource unit includes one slot in time domain, the slot includes the N symbols, and each symbol includes the M subcarriers in frequency domain, where the Nrssymbols are arranged at equal intervals based on a first value width in the N symbols, and/or the Mrssubcarriers are arranged at equal intervals based on a second value width in the M subcarriers included in each symbol of the slot, where the first value width KTmeets the following formula: KT=N/Nrs, the second value width KFmeets the following formula: KF=M/Mrs, and KTand KFare positive integers.

With reference to the second aspect, in some implementations of the second aspect, the resource unit includes S slots in time domain, each slot includes N/S symbols, each symbol includes the M subcarriers in frequency domain, and N/S is an integer, where the Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols included in the S slots, and each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols.

In some implementations of the first aspect or the second aspect, each of P antenna ports included in the set {0, 1, P−1} corresponds to a combination of one value of the frequency-domain cyclic shift factor and one value of the time-domain cyclic shift factor. When a value, corresponding to each antenna port, of the frequency-domain cyclic shift factor is uniquely determined, a value, corresponding to the antenna port, of the time-domain cyclic shift factor is also uniquely determined. Combinations, corresponding to any two of the P antenna ports, of values of the frequency-domain cyclic shift factor and values of the time-domain cyclic shift factor are different.

In some implementations of the first aspect or the second aspect, the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are respectively expressed by using the following formulas:

where

αFis the frequency-domain cyclic shift factor, NFis an integer, βEis a positive integer, a value range of βFis [0, NF−1], a, is the time-domain cyclic shift factor, NTis an integer, BTis a positive integer, and a value range of fi, is [0, NT−1].

It can be learned, according to the formulas for generating the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αT, that αFmay have a maximum of NFvalues, and αTmay have a maximum of NTvalues. Therefore, a maximum quantity of reference signals (namely, second reference signal sequences) capable of orthogonal multiplexing is NF×NT. Compared with a manner of generating a reference signal sequence by using only one cyclic shift factor, a gain of increasing a capacity of reference signals can be obtained.

According to a third aspect, a communication apparatus is provided. The communication apparatus has a function of implementing the method in any one of the first aspect or the possible implementations of the first aspect. The function may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the foregoing function.

According to a fourth aspect, this application provides a communication apparatus. The communication apparatus has a function of implementing the method in any one of the second aspect or the possible implementations of the second aspect. The function may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more units corresponding to the foregoing function.

According to a fifth aspect, this application provides a communication device, including a processor, a memory, and a transceiver. The memory is configured to store a computer program. The processor is configured to invoke and run the computer program stored in the memory, and control the transceiver to send or receive a signal, so that the communication device performs the method in any one of the first aspect or the possible implementations of the first aspect.

According to a sixth aspect, this application provides a communication device, including a processor, a memory, and a transceiver. The memory is configured to store a computer program. The processor is configured to invoke and run the computer program stored in the memory, and control the transceiver to send or receive a signal, so that the communication device performs the method in any one of the first aspect or the possible implementations of the first aspect.

According to a seventh aspect, this application provides a communication apparatus, including a processor and a communication interface. The communication interface is configured to receive a signal and transmit the received signal to the processor. The processor processes the signal, so that the method in any one of the first aspect or the possible implementations of the first aspect is performed.

According to an eighth aspect, this application provides a communication apparatus, including a processor and a communication interface. The communication interface is configured to receive a signal and transmit the received signal to the processor. The processor processes the signal, so that the method in any one of the second aspect or the possible implementations of the second aspect is performed.

Optionally, the communication interface may be an interface circuit, and the processor may be a processing circuit.

According to a ninth aspect, this application provides a computer-readable storage medium. The computer-readable storage medium stores computer instructions. When the computer instructions are run on a computer, the method in any one of the first aspect or the possible implementations of the first aspect is performed.

According to a tenth aspect, this application provides a computer-readable storage medium. The computer-readable storage medium stores computer instructions. When the computer instructions are run on a computer, the method in any one of the second aspect or the possible implementations of the second aspect is performed.

According to an eleventh aspect, this application provides a computer program product. The computer program product includes computer program code. When the computer program code is run on a computer, the method in any one of the first aspect or the possible implementations of the first aspect is performed.

According to a twelfth aspect, this application provides a computer program product. The computer program product includes computer program code. When the computer program code is run on a computer, the method in any one of the second aspect or the possible implementations of the second aspect is performed.

According to a thirteenth aspect, this application provides a chip, including a logic circuit and a communication interface. The communication interface is configured to receive to-be-processed data and/or information, and transmit the to-be-processed data and/or information to the logic circuit, the logic circuit is configured to perform processing of generating the second reference signal sequence, and the communication interface is further configured to output the second reference signal sequence.

The chip may be a chip configured in a transmit end, and the to-be-processed data may be a value of a frequency-domain cyclic shift factor and a value of a time-domain cyclic shift factor, or may be information used to indicate the value of the frequency-domain cyclic shift factor and the value of the time-domain cyclic shift factor, for example, βFand βTin the method embodiments. In addition, the to-be-processed data may further include a first reference signal sequence. The chip receives, through the communication interface, the first reference signal sequence and the information used to indicate the value of the frequency-domain cyclic shift factor and the value of the time-domain cyclic shift factor, and transmits the first reference signal sequence and the information to the logic circuit; the logic circuit processes the first reference signal sequence based on the value of the frequency-domain cyclic shift factor and the value of the time-domain cyclic shift factor, to generate the second reference signal sequence; and the chip outputs the second reference signal sequence through the communication interface.

Optionally, the communication interface may include an input interface and an output interface. The input interface is configured to receive the to-be-processed data and/or information, and the output interface is configured to output the second reference signal sequence.

According to a fourteenth aspect, this application provides a chip, including a logic circuit and a communication interface. The communication interface is configured to receive to-be-processed data and/or information, and transmit the to-be-processed data and/or information to the logic circuit, the logic circuit is configured to perform processing of demodulating the second reference signal sequence, and the communication interface is further configured to output a demodulation result.

The chip may be a chip configured in a receive end, and the to-be-processed data may be a value of a frequency-domain cyclic shift factor and a value of a time-domain cyclic shift factor, or may be information used to indicate the value of the frequency-domain cyclic shift factor and the value of the time-domain cyclic shift factor, for example, βFand βTin the method embodiments. In addition, the to-be-processed data may further include the second reference signal sequence. The chip receives, through the communication interface, the second reference signal sequence and the information used to indicate the value of the frequency-domain cyclic shift factor and the value of the time-domain cyclic shift factor, and transmits the second reference signal sequence and the information to the logic circuit; the logic circuit performs demodulation processing on the second reference signal sequence based on the value of the frequency-domain cyclic shift factor and the value of the time-domain cyclic shift factor, to obtain the demodulation result; and the chip outputs the demodulation result through the communication interface.

Optionally, the communication interface may include an input interface and an output interface. The input interface is configured to receive the to-be-processed data and/or information, and the output interface is configured to output the demodulation result.

In this embodiment of this application, the demodulation result may be a channel response of a transmit end. Optionally, if a plurality of transmit ends send reference signals to the receive end through MIMO, the demodulation result includes respective channel responses of the plurality of transmit ends.

According to a fifteenth aspect, this application provides a wireless communication system, including the communication device according to the fifth aspect and/or the communication device according to the sixth aspect.

DESCRIPTION OF EMBODIMENTS

Technical solutions of this application are applicable to the following communication systems, including but not limited to a narrowband internet of things (NB-IoT) system, a global system for mobile communications (GSM), an enhanced data rate for GSM evolution (EDGE) system, a wideband code division multiple access (WCDMA) system, a code division multiple access 2000 (CDMA2000) system, a time division-synchronization code division multiple access (TD-SCDMA) system, a long term evolution (LTE) system, three application scenarios of a fifth generation (5G) mobile communication system: eMBB, URLLC, and eMTC, and the like.

A network device in embodiments of this application is an apparatus deployed in a radio access network to provide a wireless communication function for a mobile station (MS), for example, a base station. The base station may include a macro base station, a micro base station (also referred to as a small cell), a relay station, an access point, and the like in various forms. In systems in which different radio access technologies are used, names of devices with a function of a base station may be different. For example, in a third generation (3G) system, the base station is referred to as a NodeB; in an LTE system, the base station is referred to as an evolved NodeB (eNB or eNodeB); and in a 5G system, the base station is referred to as a next generation NodeB (gNB). In addition, the network device may be alternatively a device that plays a function of a base station in device to device (D2D), machine type communication, or internet of vehicles communication, a satellite device, a base station device in a future communication network, or the like. For ease of description, in all the embodiments of this application, all the foregoing apparatuses that provide a wireless communication function for the MS are referred to as a network device or a base station or a BS. In this application, the base station may also be referred to as a base station device.

A terminal device in embodiments of this application includes various devices with a wireless communication function, for example, a handheld device, a vehicle-mounted device, a wearable device, a computing device, or another processing device connected to a wireless modem; and may be user equipment (UE), an access terminal, a subscriber unit, a subscriber station, a mobile station, a mobile console, a remote station, a remote terminal, a mobile device, a user terminal, a terminal, a wireless communication device, a user agent, or a user apparatus. Alternatively, the terminal device may be a satellite phone, a cellular phone, a smartphone, a wireless data card, a wireless modem, a machine type communication (MTC) device, a terminal device in a 5G network or a future communication network, or the like. The terminal device is also referred to as UE, a terminal, or the like.

FIG.1shows an example of an architecture of a communication system to which an embodiment of this application is applicable. As shown inFIG.1, the communication system includes one or more network devices (for example,110inFIG.1). The network device110communicates with one or more terminal devices, for example, terminal devices120and130inFIG.1. It should be understood that only one network device110and two terminal devices120and130are used as examples inFIG.1, but the communication system may alternatively include more network devices, and each network device may also communicate with one or more terminal devices.

In addition, communication between a network device and a terminal device may be uplink transmission or downlink transmission. This is not limited. For example, in downlink transmission, a transmit end in this application is a network device, for example, a base station device, and a receive end is a terminal device; and in uplink transmission, a transmit end in this application is a terminal device, and a receive end is a network device, for example, a base station device.

The following describes technical solutions of this application.

FIG.2is a schematic flowchart of a reference signal sending method according to this application. Optionally, the process shown inFIG.2may be performed by a transmit end, or may be performed by a module and/or a device (for example, a chip or an integrated circuit) or the like that is mounted in a transmit end and that has a corresponding function. The following provides descriptions by using an example in which the process is performed by a transmit end.

210: The transmit end obtains a frequency-domain cyclic shift factor and a time-domain cyclic shift factor.

The frequency-domain cyclic shift factor and the time-domain cyclic shift factor are used to perform phase rotation on a reference signal sequence.

There may be a plurality of specific implementations of obtaining, by the transmit end, the frequency-domain cyclic shift factor and the time-domain cyclic shift factor. This is not limited in this application.

For example, a receive end may notify, through indication by using signaling, the transmit end of values of the frequency-domain cyclic shift factor and the time-domain cyclic shift factor. For another example, values of some parameters used to determine the frequency-domain cyclic shift factor and the time-domain cyclic shift factor may be predefined, and the receive end notifies, through indication by using signaling, the transmit end of other parameters. The transmit end may determine respective values of the frequency-domain cyclic shift factor and the time-domain cyclic shift factor based on the predefined values of the some parameters and the values, indicated by the signaling, of the other parameters. The following describes the manners in detail.

In addition, a person skilled in the art may alternatively use another manner.

220: The transmit end generates a second reference signal sequence based on a first reference signal sequence, the frequency-domain cyclic shift factor, and the time-domain cyclic shift factor.

The transmit end may determine the first reference signal sequence in a plurality of manners, and further perform phase rotation on the first reference signal sequence by using the frequency-domain cyclic shift factor and the time-domain cyclic shift factor, to obtain the second reference signal sequence.

The following describes some manners of obtaining, by the transmit end, the first reference signal sequence as examples.

The first reference signal sequence is a ZC sequence.

For example, a first reference signal sequence whose length is Mrsmay be generated by using the following formulas:

where

xqmay be referred to as a ZC sequence whose length is NZC, where q is a root of the ZC sequence; both n and m are integers; mod indicates a modulo operation, for example, a value of 2 mod 5 is 2; NZCmay be the largest prime number less than Mrs; and usually, q and NZCare co-prime to each other.

The first reference signal sequence is generated by using a pseudo-random sequence.

For example, the transmit end may generate bit data by using the pseudo-random sequence, and modulate the bit data to obtain the first reference signal sequence. Optionally, modulation may be performed in a manner of binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), or the like.

In an example, the pseudo-random sequence used to generate the first reference signal sequence may be a Gold sequence whose length is 31 in the section 5.2.1 of the 3GPP TS38211-f80 standard.

The first reference signal sequence includes a plurality of elements. Particularly, all elements of the first reference signal sequence are the same. In this case, the first reference signal sequence may be expressed by using the following formula:

where

A is a constant, and may be a real number, an imaginary number, or a complex number.

After obtaining the first reference signal sequence, the transmit end performs phase rotation on the first reference signal sequence by using the frequency-domain cyclic shift factor and the time-domain cyclic shift factor, to obtain a plurality of second reference signal sequences. In this application, a set including the plurality of second reference signal sequences is referred to as a second reference signal sequence set.

A second reference signal sequence in the following descriptions generally means a second reference signal sequence, unless otherwise specified.

For a process of performing phase rotation on the first reference signal sequence by using the frequency-domain cyclic shift factor and the time-domain cyclic shift factor, to obtain the second reference signal sequence, refer to the following formula:

where

r1(m) indicates an element m of the first reference signal sequence, and r2,t(m) indicates an element m of a second reference signal sequence t in the second reference signal sequence set.

In addition, Mrsis a length of the second reference signal sequence (also a length of the first reference signal sequence), that is, a quantity of elements included in the second reference signal sequence, and Nrsis a quantity of second reference signal sequences included in the second reference signal sequence set, where Mrsand Nrsare positive integers.

Optionally, in an example, the first reference signal sequence belongs to a first reference signal sequence set, in other words, the first reference signal sequence set includes the first reference signal sequence, where a quantity of first reference signal sequences in the first reference signal sequence set may be greater than or equal to 1.

When the quantity of first reference signal sequences included in the first reference signal sequence set is greater than 1, any two first reference signal sequences may be the same or different.

When the quantity of first reference signal sequences included in the first reference signal sequence set is greater than 1, the second reference signal sequence may be generated by using the following formula:

where

r1,t(m) indicates an element m of a first reference signal sequence t in the first reference signal sequence set, r2,t(m) indicates the element m of the second reference signal sequence t in the second reference signal sequence set, Nrsis the quantity of second reference signal sequences included in the second reference signal sequence set, and is also the quantity of first reference signal sequences included in the first reference signal sequence set, and Mrsis a quantity of elements included in the first reference signal sequence, and is also the quantity of elements included in the second reference signal sequence.

In the manner, expressed by the formula (4) or the formula (5), of generating the second reference signal sequence, lengths of the first reference signal sequence and the second reference signal sequence are the same, that is, the first reference signal sequence and the second reference signal sequence include a same quantity of elements.

In another example, lengths of the first reference signal sequence and the second reference signal sequence may be alternatively different.

For example, a length of the first reference signal sequence is denoted as M1,rs, and a length of the second reference signal sequence is denoted as M2,rs, where M1,rsand M2,rsare positive integers.

In this implementation, the second reference signal sequence may be generated by using the following formula:

where

Δ is an offset, and Δ is an integer, and may be predefined.

It can be learned according to the formula (6) that the element m (namely, r2,t(m)) of the second reference signal sequence tin the second reference signal sequence set is obtained by performing phase rotation on an element (m+Δ)modM1,rsof the first reference signal sequence by using ej·αF·mand ej·αF·t.

The following describes in detail the frequency-domain cyclic shift factor and the time-domain cyclic shift factor in this embodiment of this application.

For ease of description, in the following descriptions, the frequency-domain cyclic shift factor is denoted as αF, and the time-domain cyclic shift factor is denoted as αT.

In this embodiment of this application, αFand αTmay be respectively determined by using the following formulas:

where

NFis an integer, βFis an integer, and a value range of βTis [0, NT−1]; and

where

NTis an integer, βTis an integer, and a value range of βTis [0, NT−1].

Optionally, in an example, βFand βTmay be configured by the receive end for the transmit end through indication by using signaling. It can be learned that, when a value of βFis any integer ranging from 0 to NF−1, a minimum quantity of bits of signaling used by the receive end to indicate βFis ┌log2NF┐. Likewise, when a value of βTis any integer ranging from 0 to NT−1, a minimum quantity of bits of signaling used by the receive end to indicate βTis ┌log2NT┐, where ┌ ┐ indicates rounding up.

Optionally, the value of βFmay be alternatively some values ranging from 0 to NF−1. For example, when a value of NFis 12, the value of βFmay be values 0, 3, 6, and 9 in 0 to 11. In this case, the value of βFmay be indicated by using 2-bit signaling. Values indicated by the 2-bit signaling are 0 to 3, and are in a one-to-one correspondence with four possible values of βF: 0, 3, 6, and 9. For example, the value 0 indicated by the 2-bit signaling corresponds to the value 0 of βFthe value 1 indicated by the signaling corresponds to the value 3 of βFthe value 2 indicated by the signaling corresponds to the value 6 of βF, and the value 3 indicated by the signaling corresponds to the value 9 of βF.

Optionally, the value of βTmay be alternatively some values ranging from 0 to NT−1. For example, when a value of NTis 8, the value of βTmay be values 0, 2, 4, and 6 in 0 to 7. In this case, the value of βTmay be indicated by using 2-bit signaling. Values indicated by the 2-bit signaling are 0 to 3, and are in a one-to-one correspondence with four possible values of βT: 0, 2, 4, and 6. For example, the value 0 indicated by the 2-bit signaling corresponds to the value 0 of βT, the value 1 indicated by the signaling corresponds to the value 2 of βTthe value 2 indicated by the signaling corresponds to the value 4 of βTand the value 3 indicated by the signaling corresponds to the value 6 of βT.

The receive end may notify, through indication by using signaling or in a predefined manner, the transmit end of NFand NT.

In the predefined manner, the value of NFmay be 2, 4, 6, 8, 10, 12, or the like; or the value of NFmay be a quantity of subcarriers included in one resource block (RB), for example, 12.

For example,

NF=6, and the value of βFis any integer ranging from 0 to NF−1. A value of αFmay be 1, π/3, 2π/3, π, 4π/3 or 5π/3.

Likewise, in the predefined manner, the value of NTmay be 2, 4, 6, 8, 10, 12, or the like; or the value of NTmay be determined by the quantity Nrsof second reference signal sequences, for example, NT=Nrs, NT=┌Nrs/K┐, or NT=└Nrs/K┘, where K is a positive integer greater than 1. For example, K=2. Particularly, when Nrs/K is an integer, the value of NTis as follows: NT=Nrs/K.

For example,

It can be learned that the first reference signal sequence t, namely, ri,t, in the first reference signal sequence set and the second reference signal sequence t, namely, r2,t, in the second reference signal sequence set meet the following formula:

It can be found that, in this embodiment of this application, a reference signal sequence actually sent by the transmit end is determined jointly by using the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αT. Different transmit ends have at least one of different αFand different αT, that is, orthogonal multiplexing can be implemented, thereby increasing a capacity of reference signals capable of orthogonal multiplexing.

It can be learned according to the formulas (7) and (8) that the frequency-domain cyclic shift factor αFmay have a maximum of NFvalues, and the time-domain cyclic shift factor αTmay have a maximum of NTvalues. Therefore, a maximum quantity of reference signals (namely, second reference signal sequences) capable of orthogonal multiplexing is NF×NT. Compared with a manner of generating a reference signal sequence by using only one cyclic shift factor, a gain of increasing a capacity of reference signals can be obtained.

In addition, in a high-speed moving scenario and/or a high-frequency scenario, a Doppler shift is significantly increased compared with that in a low-speed scenario and/or a low-frequency scenario, and overheads of reference signals need to be increased to quickly track a channel change. With this technical solution of this application applied to the high-speed moving scenario and/or the high-frequency scenario, time domain density of reference signals can be increased, so that a capacity of reference signals is increased when overheads of reference signals remain the same, or overheads of reference signals can be reduced when a capacity of reference signals remains the same.

It can be learned that the frequency-domain cyclic shift factor αFmay have a maximum of NFdifferent values, and the time-domain cyclic shift factor αTmay have a maximum of NTdifferent values. Therefore, a maximum quantity of reference signal sequences capable of orthogonal multiplexing is NF×NT. Compared with a manner of determining a reference signal sequence by using only one cyclic shift factor, a gain of increasing a capacity of reference signal sequences (namely, the second reference signal sequences in this application) can be achieved in this embodiment of this application.

As described above, the receive end may notify, through indication by using signaling, the transmit end of a, and αT. For example, the signaling may be downlink control information (DCI) or higher layer signaling, for example, radio resource control (RRC) signaling.

In this application, it is assumed that values of the frequency-domain cyclic shift factor αFconstitute a first set, and values of the time-domain cyclic shift factor αTconstitute a second set, where the first set includes Nielements, the second set includes N2elements, and N1and N2are positive integers.

A frequency-domain cyclic shift factor corresponding to an antenna port p0of the P antenna ports is an element i1in the first set, and a time-domain cyclic shift factor corresponding to the antenna port p0is an element i2in the second set; and

a frequency-domain cyclic shift factor corresponding to an antenna port p1of the P antenna ports is an element q1in the first set, and a time-domain cyclic shift factor corresponding to the antenna port p1is an element q2in the second set, where

when p0is not equal to p1, at least one of i1and q1is not equal to i2and q2respectively, to be specific, i1is not equal to i2, and q1is equal to q2; or i1is equal to i2, and q1is not equal to q2; or i1is not equal to i2, and q1is not equal to q2, where p0, p1, q1, q2, i1, and i2are integers.

αFand αTmay be determined based on a one-to-one correspondence between the values indicated by the signaling and the values of αFand αT. For example, the one-to-one mapping relationship may be expressed by using a table.

For example, αFis used as an example. Assuming that

the value of NFis 8, and the value of βFis 0 to 7, αFhas a total of eight values: 1, π/4, π/2, 3π/4, π5π/4, 3π/2, or 7π/4. In this case, the value of αFmay be indicated by using 3-bit signaling (denoted as iF). Eight different values 0 to 7 of iFare in a one-to-one correspondence with the eight values of αFrespectively, as shown in Table 1.

It should be understood that the one-to-one mapping relationship shown in Table 1 is merely used as an example, and the value of αFmay include only some values shown in Table 1. In addition, a correspondence between each value indicated by iFand the value of αFis also merely used as an example. For example, in Table 1, when the value of iFis 0, a corresponding value of αFis 1; or when the value of iFis 1, a corresponding value of αFis 1. That is, provided that different values of iFand values of αFmeet a one-to-one mapping relationship, a specific mapping relationship is not limited. Cases of other tables in the following embodiments are also similar, and descriptions are not repeated.

For example, αTis used as an example. Assuming that

the value of NTis 8, and the value of βTis 0 to 7, αThas a total of eight values: 1, π/4, π/2, 3π/4, π5π/4, 3π/2, or 7π/4. In this case, the value of αTmay be indicated by using 3-bit signaling (denoted as iT). Eight different values 0 to 7 of iTare in a one-to-one correspondence with the eight values of αTrespectively, as shown in Table 2.

The values of the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αTmay be alternatively determined by using a value indicated by same signaling.

For example, assuming that

the value of NFis 4, and the value of βFis 0 to 3, αFhas four different values: 1, π/2, π, and 3π/2; or assuming that

the value of NTis 2, and the value of βTis 0 to 1, αThas two different values: 1 and π. In this case, the values of a, and αTare determined by using 3-bit signaling (denoted as iTF). In an example for description, a determining manner is shown in Table 3.

It should be noted that the correspondence between iFand αF, the correspondence between iTand αT, and the correspondence between iTFand αFand αTin the foregoing tables are merely examples. Other possible correspondences are not excluded.

αFand αTmay be determined based on the one-to-one correspondence between the values indicated by the signaling and the values of αFand αT. It can be learned that the value of αFis in a one-to-one correspondence with the value of βF, and the value of αT, is in a one-to-one correspondence with the value of βT. Therefore, αFand αT, may be alternatively determined based on a one-to-one correspondence between the values indicated by the signaling and the values of βFand βT. For example, the one-to-one mapping relationship may be expressed by using a table.

For example, A is used as an example. Assuming that

the value of NFis 8, and the value of βFis 0 to 7. In this case, the value of βFmay be indicated by using 3-bit signaling (denoted as iF), and further, the value of αF, is determined based on the value of βF. Eight different values 0 to 7 of iFare in a one-to-one correspondence with the eight values of βFrespectively, as shown in Table 4.

For example, αTis used as an example. Assuming that

the value of NTis 8, and the value of βTis 0 to 7. In this case, the value of βTmay be indicated by using 3-bit signaling (denoted as iT), and further, the value of αTis determined based on the value of βT. Eight different values 0 to 7 of iTare in a one-to-one correspondence with the eight values of βTrespectively, as shown in Table 5.

The values of βFand βTmay be alternatively determined by using a value indicated by same signaling.

For example, it is assumed that

the value of NFis 4, and the value of βFis 0 to 3; and it is assumed that

the value of NTis 2, and the value of βTis 0 to 1. In this case, the values of βFand βTare determined by using 3-bit signaling (denoted as iTF), and further, the values of αFand αTmay be determined. In an example for description, a determining manner is shown in Table 6.

It can be learned that the values of ej·αF·mand ej·αT·tmay be determined based on the values of αFand αT. For example, when the value of αFis π/2, based on different values of m, ej·αF·mis obtained by repeating a sequence [1, j, −1, −j]. Assuming that

it can be learned that NFconsecutive elements in ej·αF·mhave different values, and there are only NFpossible values. Therefore, it can be learned according to the formula (7) and the formula (8) that ej·αF·mhas NFpossible values, and ej·αT·thas NTpossible values.

Therefore, an element0to an element NF−1 in ej·αF·mmay be expressed as a sequence WFwhose length is NF, and an element0to an element NT−1 in ej·αT·tmay be expressed as a sequence WTwhose length is NT. In this case, ej·αF·mand ej·αT·tmay be expressed as follows:

Therefore, ej·αF·mand ej·αT·tmay be further determined based on a one-to-one correspondence between the values indicated by the signaling and the sequence WFand the sequence WT. For example, the one-to-one mapping relationship may be expressed by using a table.

For example, it is assumed that the value of NFis 4 and the value of NTis 2. In this case, values of the sequence WFand the sequence WTare determined by using 3-bit signaling (denoted as iTF), and further, the values of ej·αF·mand ej·αT·tmay be determined. NFelements of the sequence WFmay be expressed as [WF(0), WF(1), WF(2), WF(3)]. NTelements of the sequence WTmay be expressed as [WT(0), WT(1)]. In an example for description, a determining manner is shown in Table 7.

Frequency-domain cyclic shift factors αFand time-domain cyclic shift factors αTof different cells may be configured to be different, to reduce mutual interference between data sent by terminal devices of different cells, and alleviate inter-cell interference.

After generating the second reference signal sequence by using the foregoing method, the transmit end sends the second reference signal sequence to the receive end, as described in step230.

230: The transmit end sends the second reference signal sequence on an antenna port p.

The antenna port p∈{0, 1, . . . , P−1}, and P is an integer greater than or equal to 1.

One second reference signal sequence is carried in one symbol in time domain. Assuming that the symbol includes M subcarriers in frequency domain, the second reference signal sequence is mapped to Mrssubcarriers of the M subcarriers included in the symbol in frequency domain.

For example, a second reference signal sequence whose length is Mrs(that is, including Mrselements) may be mapped onto the Mrssubcarriers to obtain a frequency domain signal, and the transmit end sends a time domain signal, where the frequency domain signal may be converted into a time domain signal through inverse Fourier transform.

As described above, the second reference signal sequence set includes Nrssecond reference signal sequences, and the Nrssecond reference signal sequences may be sent on Nrssymbols in time domain. The Nrssecond reference signal sequences are in a one-to-one correspondence with the Nrssymbols, and each second reference signal sequence is mapped to a corresponding symbol.

Optionally, the Nrssymbols are included in one resource unit, in other words, the transmit end sends second reference signal sequences on Nrssymbols in one resource unit.

For example, one resource unit may be one RB or a plurality of RBs. The plurality of RBs may be continuously or discretely distributed. Pilot patterns of different RBs may be the same or different. This is not limited in this application. Without loss of generality, that one RB serves as one resource unit is used as an example below, unless otherwise specified.

Assuming that the resource unit includes N symbols and each symbol includes M subcarriers in frequency domain, N≥Nrs, and M≥Mrs, where both N and M are positive integers.

In an example, when N>Nrsor M>Mrsis met, no second reference signal sequence is mapped to idle subcarriers included in the resource unit, and the idle subcarriers may be used to carry data. Optionally, when data is sent by using an orthogonal frequency division multiplexing (OFDM) waveform, the data carried in the idle subcarriers is modulated data; or when data is sent by using a single-carrier frequency-division multiple access (SC-FDMA) waveform, the data carried in the idle subcarriers is output data obtained by performing Fourier transform on modulated data.

In a specific implementation, there may be a plurality of mapping manners for the second reference signal sequence on a time-frequency resource. An example is used for description below.

For example, the resource unit includes one slot in time domain, the slot includes N symbols, and each symbol includes M subcarriers in frequency domain. The Nrssymbols used to carry second reference signal sequences are arranged at equal intervals based on a first value width in the N symbols of the slot. In addition, in each symbol, the Mrssubcarriers used to carry a second reference signal sequence are arranged at equal intervals based on a second value width in the M subcarriers included in the symbol. The first value width KTmeets the following formula: Kr=N/Nrs, and the second value width KFmeets the following formula: KF=M/Mrs, where KTand KFare positive integers.

The second reference signal sequences are configured to be arranged in a comb tooth form in time domain and in frequency domain, and a comb tooth size (for example, the first value width or the second value width) may be adjusted, so that density of reference signals (namely, second reference signal sequences) sent in one resource unit, that is, overheads of reference signals, can be flexibly adjusted, to meet requirements in different scenarios, for example, a low-speed scenario and a high-speed scenario.

In some embodiments, the Nrssymbols are arranged at equal intervals based on the first value width in the N symbols, and/or the Mrssubcarriers are arranged at equal intervals based on the second value width in the M subcarriers. That is, the second reference signal sequences may be arranged at equal intervals only in time domain, or may be arranged at equal intervals only in frequency domain, or may be arranged at equal intervals both in time domain and in frequency domain. In addition, the second reference signal sequences may be alternatively arranged at non-equal intervals both in time domain and in frequency domain. This is not limited.

FIG.3is used as an example for description below.

FIG.3shows an example of a mapping pattern of second reference signal sequences in one resource unit. As shown inFIG.3, it is assumed that the resource unit includes one slot, the slot includes 14 symbols, that is, N=14, and one symbol includes 12 subcarriers, that is, M=12. A time domain position (also referred to as a time domain index) of a starting symbol of the 14 symbols is denoted as tstart, and a frequency domain position (also referred to as a frequency domain index) of a starting subcarrier of the 12 subcarriers is denoted as kstart. As shown inFIG.3, a length Mrsof the second reference signal sequence is 4, and a quantity Nrsof second reference signal sequences is 7. The seven second reference signal sequences in the second reference signal sequence set are arranged at equal intervals based on the first value width KT, which is 2, in the 14 symbols of the shown slot, and each second reference signal sequence is arranged at equal intervals based on the second value width KF, which is 3, in a corresponding symbol.

As shown inFIG.3, it is assumed that a time domain position set of the Nrssecond reference signal sequences is denoted as tidx, and a frequency domain position set is denoted as kidx.

In an implementation, a time domain position included in the time domain position set tidxmay be a relative position relative to the time domain position tstartof the starting symbol, and a frequency domain position included in the frequency domain position set kidxmay be a relative position relative to the frequency domain position kstartof the starting subcarrier.FIG.3is used as an example, where the time domain position set tidxis [0, 2, 4, 6, 8, 10, 12], and the frequency domain position set kidxis [0, 3, 6, 9].

In another implementation, a time domain position included in the time domain position set tidxmay be an absolute position, and a frequency domain position included in the frequency domain position set kidxmay also be an absolute position.FIG.3is still used as an example, where tidx=[tstart, tstart+2, tstart+4, tstart+6, tstart+8, tstart+10, tstart+12], and kidx=[kstart, kstart+3, kstart+6, kstart9].

The foregoing resource unit may include one slot, and the slot includes Nrepsymb×Nbasesymbsymbols, where both Nrepsymband Nbasesymbare positive integers, and Nbasesymbmay be known based on an agreement between the transmit end and the receive end. Nbasesymbmay be a minimum quantity of symbols included in one resource unit, and the receive end may notify the transmit end of Nrepsymbthrough indication by using signaling.

For example, Nrepsymbmay have four values: 1, 2, 4, and 8. In this case, the receive end may perform indication to the transmit end by using 2-bit signaling. In another case, Nrepsymbmay be alternatively implicitly determined based on the first value width KTin the foregoing descriptions.

In addition, in an example, for different subcarrier spacings, one slot may include different quantities of symbols. At a specific subcarrier spacing, one slot may be configured, through indication by using signaling, to include different quantities of symbols, to adjust a quantity of symbols in time domain that are used to send reference signals, so as to flexibly adapt to requirements in different scenarios. For example, if a large capacity of reference signals is required, one slot may be configured, by using signaling, to include a larger quantity of symbols, so that a larger quantity of symbols are used to send reference signals, a value range of the time-domain cyclic shift factor αTis larger, and a larger quantity of orthogonal multiplexing reference signals are supported.

For example, the resource unit includes a plurality of slots in time domain. For example, one resource unit may include Nslotslots, where Nslotis a positive integer, and the receive end may notify the transmit end of Nslotthrough indication by using signaling. In this case, values of elements in the time domain position set tidxspan a plurality of slots.

For example, one resource unit includes four slots, each slot includes 14 symbols, and symbols2,5,8, and11of each slot are used to send second reference signal sequences, as shown inFIG.4.

FIG.4shows an example of a mapping pattern of second reference signal sequences in one resource unit. It is assumed that an index of a time domain position of a starting symbol starts from0, and symbols2,5,8, and11of each slot are used to carry second reference signal sequences. A time domain position of a starting symbol of the four slots is tstart. It can be learned that time domain positions of all symbols of the four slots may be expressed as tstart, tstart+1, tstart+2, . . . , and tstart+55. In this case, the time domain position set tidxis expressed by using phase positions, and tidx=[2, 5, 8, 11, 16, 19, 22, 25, 30, 33, 36, 39, 44, 47, 50, 53].

For example, the resource unit includes a plurality of slots in time domain. When the Nrssymbols are arranged at equal intervals based on the first value width in the N symbols, quantities and time domain positions of symbols, to which reference signal sequences are mapped, in different slots of the resource unit may be different.

For example, one resource unit includes four slots, each slot includes 14 symbols, and time domain positions of all symbols in the four slots may be expressed as tstart, tstart+1, tstart2, . . . , tstart+55. It is assumed that the Nrssymbols corresponding to the Nrssecond reference signal sequences are arranged at equal intervals based on the first value width KT, which is 3, in the N symbols, and a position of a symbol corresponding to a second reference signal sequence0in the N symbols is 2. In this case, it can be learned that Nrs=18. The time domain position set tidxis expressed by using relative positions. In this case, tidx=[2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47, 50, 53]. It can be learned that time domain positions of symbols, in a slot0(corresponding to relative positions0to13) of the resource unit, for sending second reference signal sequences are 2, 5, 8, and 11; time domain positions of symbols, in a slot1(corresponding to relative positions14to27), for sending second reference signal sequences are 14, 17, 20, 23, and 26; time domain positions of symbols, in a slot2(corresponding to relative positions28to41), for sending second reference signal sequences are 29, 32, 35, 38, and 41; and time domain positions of symbols, in a slot3(corresponding to relative positions42to55), for sending second reference signal sequences are 44, 47, 50, and 53.

For data sent in the resource unit, a possibility is that data generated by using to-be-sent bits corresponding to one transport block (TB) is sent in one slot, where the data may be generated by performing operations such as encoding, interleaving, rate matching, and modulation on the to-be-sent bits. In this case, the data generated by performing the operations such as encoding, interleaving, rate matching, and modulation on the to-be-sent bits is mapped to one slot for sending. Data sent in different slots may be a repetition of data sent in one slot. For example, redundancy versions (RV) of different slots may be the same or different. This is not limited.

When the resource unit includes a plurality of slots, a possibility is that data generated by using to-be-sent bits corresponding to one TB is sent in the plurality of slots, where the data may be generated by performing operations such as encoding, interleaving, rate matching, and modulation on the to-be-sent bits. In this case, the data generated by performing the operations such as encoding, interleaving, rate matching, and modulation on the to-be-sent bits is mapped to the plurality of slots for sending.

Optionally, in an example, time domain positions and frequency domain positions of the second reference signal sequences may be described in the following manner.

The second reference signal sequences are mapped to Mrssubcarriers, where frequency domain positions corresponding to the Mrssubcarriers are included in a frequency domain position set kidx, and a frequency domain position corresponding to a subcarrier to which an element m, namely, r2,t(m), of a second reference signal sequence t, namely, r2,t, in the second reference signal sequence set is mapped is kidx(m).

Nrssecond reference signal sequences in the second reference signal sequence set are sent on Nrssymbols, the Nrssymbols are included in N symbols of a resource unit, and a set including time domain positions corresponding to the Nrssymbols is denoted as a time domain position set tidx. In this case, a time domain position of a symbol corresponding to the second reference signal sequence t, namely, r2,t, is tidx(t).

Optionally, the frequency domain positions of the second reference signal sequences may be continuous, where in this case, Mrs=M; or may be discrete. Optionally, the time domain positions of the second reference signal sequences may be continuous, where in this case, Nrs=N; or may be discrete.

For example, one resource unit may include one slot, one slot includes 14 (N=14) symbols, time domain indexes of the 14 symbols are denoted as 0 to 13, and a quantity Nrsof second reference signal sequences is 4. In this case, time domain indexes, in the 14 symbols included in the slot, of the four symbols for carrying the second reference signal sequences may be 2, 5, 8, and 11, that is, tidx=[2, 5, 8, 11]. In addition, frequency domain indexes may be 0, 2, 4, 6, 8, and 10, that is, kidx=[0, 2, 4, 6, 8, 10].FIG.5shows an example of a mapping pattern of second reference signal sequences in one resource unit.

The foregoing describes implementations of performing, by the transmit end, phase rotation on the first reference signal sequence by using the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αT, to obtain the second reference signal sequence, and sending, by the transmit end, the second reference signal sequence in this application.

With reference toFIG.6, the following describes a process of sending a reference signal sequence and receiving the reference signal sequence in an embodiment of this application.

FIG.6shows an example of a flowchart of sending and receiving a second reference signal sequence.

610: A transmit end obtains a frequency-domain cyclic shift factor αF, and a time-domain cyclic shift factor αT.

Optionally, if second reference signal sequences are distributed on a time-frequency resource in the comb tooth pattern shown inFIG.3, in step610, the transmit end further needs to obtain information such as a first value width and a second value width.

A receive end may notify the transmit end of all of the foregoing information by using signaling, or some information may be predefined.

620: The transmit end generates a second reference signal sequence based on the obtained information and a first reference signal sequence.

In addition, the transmit end generates data.

630: The transmit end maps the second reference signal sequence and the data to a corresponding time-frequency resource.

640: The transmit end sends the second reference signal sequence and the data on an antenna port p.

The receive end receives the second reference signal and the data from the antenna port p of the transmit end.

650: The receive end performs channel estimation by using the received second reference signal sequence, to obtain a channel response.

It should be noted that, if a plurality of transmit ends send data to the receive end through MIMO, in a channel estimation process, the receive end distinguishes between channel responses of different transmit ends based on the fact that frequency-domain cyclic shift factors αF, and time-domain cyclic shift factors c of the different transmit ends are orthogonal.

Alternatively, if a transmit end sends data to the receive end by using a plurality of antenna ports through MIMO, in a channel estimation process, the receive end distinguishes between channel responses of different antenna ports based on the fact that frequency-domain cyclic shift factors αF, and time-domain cyclic shift factors αTcorresponding to the antenna ports used by the transmit end are orthogonal.

Second reference signal sequences sent by the transmit end on Nrssymbols are known to the receive end. The receive end performs channel estimation based on second reference signal sequences actually received on Nrssymbols and the known second reference signal sequences, to obtain a frequency domain channel response of the Nrssymbols. In the following descriptions, a frequency domain channel response of each of the Nrssymbols is denoted as Ht, where 0≤t<Nrs, and Htincludes Mrselements.

The receive end performs inverse Fourier transform on the frequency domain channel response Htof each symbol to obtain an output ht, and performs Fourier transform on elements with a same index in outputs htof different symbols to obtain a channel response htDDin delay-Doppler domain, where elements m in the outputs htof the different symbols may be denoted as ht(m). It is assumed that htDD(m)=hmatrix(t,m), where 0≤m<Mrs, and 0≤t<Nrs. It can be learned that hmatrix(t,m) is a matrix whose size is Nrs×Mrs, and includes Nrs×Mrselements.

According to an aggregation characteristic of a time domain channel response, an amplitude of the time domain channel response is high within a period of time in time domain, and an amplitude beyond this period of time is quite low, and may be basically ignored. Likewise, a channel response also has an aggregation characteristic in delay-Doppler domain. To be specific, amplitudes of elements in some regions of a channel response hmatrix(t,m) in delay-Doppler domain are high, and amplitudes of elements in other regions are quite low, and may be basically ignored.

Therefore, for different values of the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αTregions in which channel responses are aggregated in delay-Doppler domain are different. That is, for different transmit ends, different values of the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αT, are configured, so that channel responses of the different transmit ends in delay-Doppler domain are aggregated in different regions. For each transmit end, an aggregation region of a channel response of each transmit end in hmatrix(t,m) is determined based on values of the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αTof each transmit end, and then the receive end extracts the channel response of each transmit end by performing an operation such as filtering or windowing. The channel response of each transmit end is not affected by a channel response of another transmit end.

After obtaining the channel response hmatrix(t,m) in delay-Doppler domain, the receive end obtains a processed channel response hmatrixfilter(t,m) by performing an operation such as filtering or windowing. The receive end performs inverse Fourier transform on elements with a same index (for example, elements m of different symbols) in hmatrixfilter(t,m)corresponding to different symbols t, and then performs Fourier transform on an output result of each symbol in an output result of the inverse Fourier transform, to obtain a new frequency domain channel response htfilterof each symbol.

Finally, the receive end may obtain a frequency domain channel response of the other (N−Nrs) symbols through interpolation by using the new frequency domain channel response htfilterof the Nrssymbols, and then perform, by using the frequency domain channel response obtained through interpolation, operations such as equalization, demodulation, and decoding on data received from the transmit end, to obtain data sent by the transmit end, as described in step660.

660: The receive end performs, by using the channel response, processing such as equalization, demodulation, and decoding on data received from the transmit end, to obtain data sent by the transmit end.

In the foregoing embodiment, the transmit end sends the second reference signal sequence on the antenna port p, where the antenna port p∈{0, 1, P−1}, and P is an integer greater than or equal to 1. That is, the transmit end may send the second reference signal sequence by using some or all of the P antenna ports.

Each of the P antenna ports uniquely corresponds to a combination of one value of αFand one value of αT. When a value, corresponding to each of the P antenna ports, of αF, is determined, a value, corresponding to the antenna port, of αTis also uniquely determined. In other words, when a value, corresponding to each of the P antenna ports, of αTis determined, a value, corresponding to the antenna port, of αFis also uniquely determined. Combinations, corresponding to any two of the P antenna ports, of values of αFand values of αTare different.

It should be understood that, that combinations, corresponding to any two antenna ports, of values of αFand values of αFare different indicates that any two antenna ports correspond to at least one of different values of αFand different values of αT. For example, values of αTare different, and values of αTare the same; or values of αFare the same, and values of αTare different; or values of αFare different, and values of αTare also different.

It can be understood that different values of αFPand αTPmay be used for different antenna ports, and values of αFPand αTPof different antenna ports may be flexibly configured, to implement orthogonal multiplexing of reference signals between antenna ports, thereby increasing a quantity of antenna ports that can be supported.

Based on a one-to-one mapping relationship between the P antenna ports and the frequency-domain cyclic shift factor αFand the time-domain cyclic shift factor αT, for a process of generating the second reference signal sequence sent on the antenna port p, refer to the following descriptions:

The transmit end determines the first reference signal sequence, and performs phase rotation on the first reference signal sequence by using a frequency-domain cyclic shift factor αFand a time-domain cyclic shift factor αT, that correspond to the antenna port p, to obtain the second reference signal sequence of the antenna port p.

The second reference signal sequence of the antenna port p belongs to a second reference signal sequence set r2pcorresponding to the antenna port p, and the second reference signal sequence t in the second reference signal sequence set r2pmay be generated by using a formula (12):

r1p(m) indicates an element m of the first reference signal sequence corresponding to the antenna port p, r2Pt(m) indicates an element m of the second reference signal sequence t corresponding to the antenna port p, and P is a quantity of antenna ports.

Optionally, in an example, first reference signal sequences corresponding to two different antenna ports of the P antenna ports may be the same, and may be expressed as r1P. In this case, the second reference signal sequence is generated based on the foregoing formula (12).

In another example, first reference signal sequences corresponding to two different antenna ports of the P antenna ports are different. In this case, the first reference signal sequence corresponding to the antenna port p belongs to a first reference signal sequence set r1Pcorresponding to the antenna port p. In this case, the second reference signal sequence is generated based on the following formula (13):

where

r1,tp(m) indicates an element m of a first reference signal sequence t corresponding to the antenna port p, r2,tp(m) indicates an element m of the second reference signal sequence t corresponding to the antenna port p, and P is a quantity of antenna ports.

For a manner of generating the first reference signal sequence in the foregoing formula (12) or formula (13), refer to the foregoing descriptions. Details are not described again.

In addition, in another embodiment, the transmit end generates a second reference signal sequence r2,tby using the foregoing formula (5), and then performs phase rotation on the second reference signal sequence by using the frequency-domain cyclic shift factor (denoted as αFP) and the time-domain cyclic shift factor (denoted as αTP) that correspond to the antenna port p, to obtain a second reference signal sequence r2,tp, of the antenna port p.

The second reference signal sequence of the antenna port p belongs to the second reference signal sequence set r2pcorresponding to the antenna port p. The second reference signal sequence t, namely, r2,tp, of the antenna port p in r2pmay be generated based on the following formulas (14) and (15):

It can be learned according to the formula (5) that the formula (14) may be further expanded to obtain the formula (15):

r2,tp(m) indicates an element m of r2,tp. For r1,t(m), αFp, and αTp, refer to the descriptions of r1,t(m) αF, and αTin the formula (5) respectively.

In this embodiment, the frequency-domain cyclic shift factor αFand αTthe time-domain cyclic shift factor αTmay be configured at a cell level, and values of αFand αTof different cells may be configured to be different, to reduce mutual interference between data sent by transmit ends of different cells, and alleviate inter-cell interference.

After obtaining the second reference signal sequence of the antenna port p in the foregoing manner, the transmit end sends the second reference signal sequence to the receive end. Time domain positions and frequency domain positions of second reference signal sequences of the P antenna ports may be the same or different. This is not limited.

In addition, in the foregoing embodiment related to the antenna port p, the frequency-domain cyclic shift factor corresponding to the antenna port p is denoted as G, and the time-domain cyclic shift factor corresponding to the antenna port p is denoted as Cif.

αFpand αTpmay be respectively determined by using the following formulas:

where

NFpis an integer, βFpis an integer, and a value range of βFpis [0, NFp−1]; and

where

NTpis an integer, βTpis an integer, and a value range of βTpis [0, NTP−1].

Optionally, in an implementation, NFpcorresponding to different antenna ports of the P antenna ports may be the same. In this case, NFpmay be denoted as NF. Alternatively, NFpcorresponding to different antenna ports may be different.

Likewise, NTpcorresponding to different antenna ports of the P antenna ports may be the same. In this case, NTpmay be denoted as NT. Alternatively, NTpcorresponding to different antenna ports may be different.

For example, values of αFp, NFp, and βFpare the same as the values of αF, NF, and βFdefined in the foregoing formula (7). Likewise, values of αTp, NTp, and βTpmay be alternatively the same as the values of αT, NT, and βTdefined in the foregoing formula (8).

For example, values of αFpand αTpmay be alternatively the same as the values of αFand αTlisted in Table 1 to Table 3.

Different values of αFpand αTpare configured for different antenna ports, so that orthogonal multiplexing of reference signals between antenna ports can be implemented, and a quantity of antenna ports that can be supported can be increased. Therefore, values of αFpand αTpof different antenna ports can be flexibly configured.

As described above, each of the P antenna ports uniquely corresponds to a combination of one value of the frequency-domain cyclic shift factor and one value of the time-domain cyclic shift factor, and different antenna ports correspond to at least one of different values of αFpand different values of αTp.

For example,

βFphas NFdifferent values, and βTphas NTdifferent values. Therefore, a maximum quantity of antenna ports that can be supported is P=NF×NT.

A relationship between βFpand βTpand the antenna port p may be determined in the following manner.

For example, βFpand βTpare determined by using the following formulas (18) and (19) respectively:

where

mod indicates a modulo operation, a value of p is any integer ranging from 0 to P−1, and ΔFand ΔTare predefined integers, for example, ΔF=0, or ΔF=└NF/2┘, and ΔT=0, or ΔT=└NT/2┘.

For example, βFpand βTpmay be alternatively determined by using the following formulas (20) and (21) respectively:

where

mod indicates a modulo operation, and a value of p is any integer ranging from 0 to P−1. In an example, NF=4, NT=2, ΔF=0, and ΔT=0. In this case, G and ac are shown in formulas (22) and (23) respectively:

For example, a correspondence between the antenna port p and a value of αFpand a value of αTpmay be alternatively expressed by using a table. For ease of description, in the following example, assuming that NFpcorresponding to different antenna ports of the P antenna ports is the same, NFpmay be denoted as NFin this case; and assuming that NTPcorresponding to different antenna ports of the P antenna ports is the same, NTPmay be denoted as NTin this case.

For example, in an example, αFphas four different values: 1,

π, and

and αTphas two different values: 1 and π. Therefore, eight antenna ports can be supported, and the correspondence between the antenna port p and the value of αFpand the value of αTpmay be shown in Table 8, where p∈{0, 1, . . . , 7}.

In another example, αFpand has four different values: 1,

π, and

and αTphas three different values: 1,

Therefore, 12 antenna ports can be supported, and the correspondence between the antenna port p and the value of αFpand the value of αTpmay be shown in Table 9, where p∈{0, 1, . . . , 11}.

π, and

and αTphas four different values: 1,

π, and

Therefore, 16 antenna ports can be supported, and the correspondence between the antenna port p and the value of αFpand the value of αTpmay be shown in Table 10, where p∈{0, 1, . . . , 15}.

It can be learned from Table 8 to Table 10 that the antenna port p is in a one-to-one correspondence with the values of αFpand αTp, and different antenna ports correspond to at least one of different values of αFpand different values of αTp, so that a quantity of signaling bits can be reduced, and signaling overheads can be reduced.

In addition, it can be learned that the value of αFpis in a one-to-one correspondence with the value of βFp, and the value of αTpis in a one-to-one correspondence with the value of βTp. Provided that the values of βFpand βTpare determined, the values of αFpand βTpcan be determined. Therefore, each of the P antenna ports may also uniquely correspond to a combination of one value of βFpand one value of βTpand different antenna ports correspond to at least one of different values of βFpand different values of βTp.

A correspondence between the antenna port p and a value of βFpand a value of βTpmay be alternatively expressed by using a table.

For example, in an example, the value of NFis 4, βFphas four different values: 0, 1, 2, and 3; and the value of NTis 2, and βTphas two different values: 0 and 1. Therefore, eight antenna ports can be supported, and the correspondence between the antenna port p and the value of βFpand the value of βTpmay be shown in Table 11, where p∈{0, 1, . . . , 7}.

In another example, the value of NFis 4, βFphas four different values: 0, 1, 2, and 3; and the value of NTis 3, and βTphas three different values: 0, 1, and 2. Therefore, 12 antenna ports can be supported, and the correspondence between the antenna port p and the value of βFpand the value of βTpmay be shown in Table 12, where p∈{0, 1, . . . , 11}.

In another example, the value of NFis 4, βFphas four different values: 0, 1, 2, and 3; and the value of NTis 4, and βTphas four different values: 0, 1, 2, and 3. Therefore, 16 antenna ports can be supported, and the correspondence between the antenna port p and the value of βFpand the value of βTpmay be shown in Table 13, where p∈{0, 1, . . . , 15}.

After the values of βFpand βTpare determined based on the table, the values of αFpand αTpmay be determined by using the formulas (16) and (17).

It can be learned that the values of

may be determined based on the values of αFpand αTp. For example, when the value of αFpis π/2, based on different values of m,

is obtained by repeating a sequence [1, j, −1, −j].

has NTpossible values, and

Therefore, an element0to an element NF−1 in

corresponding to the antenna port p may be expressed as a sequence WFpwhose length is NF, and an element0to an element NT−1 in

may be expressed as a sequence WTpwhose length is NT. In this case,

may be expressed as follows:

may be further determined based on a one-to-one correspondence between values indicated by signaling and the sequence WFpand the sequence WTp. Optionally, the one-to-one mapping relationship may be expressed by using a table.

For example, it is assumed that the value of NFis 4 and the value of NTis 4. In this case, values of the sequence WFpand the sequence WTpmay be determined by using 4-bit signaling, and further, the values of

may be determined. An element NFof the sequence WFpmay be expressed as [WFp(0), WFp(1), WFp(2), WFp(3)]. An element NTof the sequence WTpmay be expressed as [WTp(0), WTp(1), WTp(2), WTp(3)]. In an example for description, a determining manner is shown in Table 14.

Optionally, in an embodiment, the values of the antenna port p in the foregoing tables may be indicated by using DCI.

It can be learned from the foregoing embodiment that different values of αFpand αTpare used for different antenna ports, so that orthogonal multiplexing of reference signal sequences between the different antenna ports can be implemented, thereby increasing a quantity of antenna ports that can be supported.

In the foregoing embodiment related to the antenna port, Nrssecond reference signal sequences sent by different antenna ports are mapped to same time domain positions and frequency domain positions. In some other embodiments, Nrssecond reference signal sequences sent by different antenna ports may be mapped to different time domain positions and/or frequency domain positions. Descriptions are provided below.

Frequency domain positions to which Nrssecond reference signal sequences sent by the antenna port p are mapped are included in a frequency domain position set kidxP, where a frequency domain position corresponding to a subcarrier to which an element m, namely, r2,t(m), of a second reference signal sequence t, namely, r2,t, is mapped is kidxP(m), and kidxPincludes Mrselements.

Time domain positions to which the Nrssecond reference signal sequences sent by the antenna port p are mapped are included in a time domain position set tidxP, where a time domain position of a symbol corresponding to the second reference signal sequence t, namely, r2,t, is kidxP(t), and kidxPincludes Nrselements.

The frequency domain position set kidxPis an element in a first frequency domain position set Kidx, and the time domain position set tidxPis an element in a first time domain position set Tidx. Any two elements in the first frequency domain position set are different, and any two elements in the first time domain position set are different.

A quantity of elements in the first frequency domain position set Kidxis Nidx,K, where Nidx,Kis a positive integer. An element i in the first frequency domain position set Kidx, may be denoted as Kidxi, and the element i, namely, Kidxi, includes Mrsvalues, where a value range of i is [0, Nidx,K−1]. That any two elements in the first frequency domain position set are different indicates that values m of any two elements are different, that is, when i and j are different, Kidxi(m) and Kidxj(m) are different, where i∈[0, Nidx,K−1], j∈[0, Nidx,K−1], and a value range of m is [0, Mrs−1].

A quantity of elements in the first time domain position set Tidxis Nidx,T, where Nidx,Tis a positive integer. An element i in the first time domain position set Tidxmay be denoted as Tidxi, and the element i, namely, Tidxi, includes Nrsvalues. That any two elements in the first time domain position set are different indicates that values m of any two elements are different, that is, when i and j are different, Tidxi(m) and Tidxj(m) are different, where i∈[0, Nidx,T−1], j∈[0, Nidx,T−1], and a value range of m is [0, Nrs−1].

Frequency domain positions to which Nrssecond reference signal sequences of different antenna ports are mapped may be different, that is, may be different elements in the first frequency domain position set Kidx. For example, the first frequency domain position set Kidxincludes two elements, that is, Nidx,K=2. In this case, frequency domain positions to which Nrssecond reference signal sequences of an antenna port p0are mapped, that is, a frequency domain position set kidx0, may be Kidx0and frequency domain positions to which Nrssecond reference signal sequences of an antenna port p1are mapped, that is, a frequency domain position set kidx1may be Kidx1, where values of p0and p1are different, p0∈{0, 1, P−1}, and p1∈{0, 1, . . . , P−1}.

Time domain positions to which Nrssecond reference signal sequences of different antenna ports are mapped may be different, that is, may be different elements in the first time domain position set Tidx. For example, the first time domain position set Tidxincludes two elements, that is, Nidx,T=2. In this case, time domain positions to which Nrssecond reference signal sequences of an antenna port p0are mapped, that is, a time domain position set tidx0, may be Tidx0; and time domain positions to which Nrssecond reference signal sequences of an antenna port p1are mapped, that is, a time domain position set ta, may be T.

For a time domain position and a frequency domain position to which a second reference signal sequence of an antenna port may be mapped, several examples are listed below.

For example, Nidx,T=1, and Nidx,K>1. An example is shown inFIG.7.FIG.7shows an example of time-frequency positions to which second reference signal sequences of antenna ports are mapped. InFIG.7, one resource unit includes one slot, one slot includes 14 symbols, that is, N=14, indexes of the 14 symbols are 0 to 13, each slot includes 12 subcarriers, that is, M=12, and indexes of the 12 subcarriers are 0 to 11. It is assumed that Nrs=4 and Mrs=6, to be specific, there are four second reference signal sequences, and each second reference signal sequence includes six elements. InFIG.7, a first time domain position set Tidxincludes one element, and a value Tidx0of the element is [2, 5, 8, 11]; and a first frequency domain position set Kidxincludes two elements, where an element0Kidx0is [0, 2, 4, 6, 8, 10], and an element1Kidx1is [1, 3, 5, 7, 9, 11].

It should be noted that a quantity of symbols included in one resource unit and a quantity of subcarriers that correspond to each symbol in frequency domain and that are used for sending data inFIG.7are merely examples, and may alternatively have other values.

For another example, Nidx,T>1, and Nidx,K=1. An example is shown inFIG.8.FIG.8shows an example of time-frequency positions to which second reference signal sequences of antenna ports are mapped. InFIG.8, one resource unit includes one slot, one slot includes 14 symbols, that is, N=14, indexes of the 14 symbols are 0 to 13, each slot includes 12 subcarriers, that is, M=12, and indexes of the 12 subcarriers are 0 to 11. It is assumed that Nrs=4 and Mrs=6, to be specific, there are four second reference signal sequences, and each second reference signal sequence includes six elements. InFIG.8, a first time domain position set Tidxincludes two elements, where a value of an element0Tidx0is [1, 4, 7, 10], and a value of an element1Tidx1is [2, 5, 8, 11]; and a first frequency domain position set Kidxincludes one element, and a value Kidx0of the element is [0, 2, 4, 6, 8, 10].

For another example, Nidx,T>1, and Nidx,K>1. An example is shown inFIG.9.FIG.9shows an example of time-frequency positions to which second reference signal sequences of antenna ports are mapped. InFIG.9, one resource unit includes two slots, one slot includes 14 symbols, that is, the resource unit includes 28 symbols, indexes of the 28 symbols are 0 to 27, each symbol includes 12 subcarriers, that is, M=12, and indexes of the 12 subcarriers are 0 to 11. It is assumed that Nrs=7 and Mrs=6, to be specific, there are seven second reference signal sequences, and each second reference signal sequence includes six elements. InFIG.9, a first time domain position set Tidxincludes two elements, where a value of an element0Tidx0is [0, 4, 8, 12, 16, 20, 24], and a value of an element1Tidx1, is [2, 6, 10, 14, 18, 22, 26]; and a first frequency domain position set Kidx, includes two elements, where a value of an element0Kidx0is [0, 2, 4, 6, 8, 10], and a value of an element1Kidx1is [1, 3, 5, 7, 9, 11].

It can be learned that, when Nrssecond reference signal sequences of two antenna ports are mapped to different time domain positions, reference signals (namely, second reference signal sequences) sent by the two antenna ports are orthogonal. Likewise, when Nrssecond reference signal sequences of two antenna ports are mapped to different frequency domain positions, reference signals (namely, second reference signal sequences) sent by the two antenna ports are orthogonal. Therefore, based on the quantity Nidx,Kof elements included in the first frequency domain position set Kidxand the quantity Nidx,Tof elements included in the first time domain position set Tidx, Nidx,K×Nidx,Tdifferent antenna ports may be provided for sending reference signals.

Orthogonality of reference signal sequences may be implemented for different antenna ports by using different combinations of time domain positions and frequency domain positions of second reference signal sequences, the frequency-domain cyclic shift factor, and the time-domain cyclic shift factor.

Each of the P antenna ports corresponds to a combination of one value of the frequency-domain cyclic shift factor, one value of the time-domain cyclic shift factor, and a time domain position and a frequency domain position of a second reference signal sequence. Any two of the P antenna ports correspond to different combinations of values of the frequency-domain cyclic shift factor, values of the time-domain cyclic shift factor, and time domain positions and frequency domain positions of second reference signal sequences.

Therefore, it can be learned that, based on the quantity NFof values of the frequency-domain cyclic shift factor, the quantity NTof values of the time-domain cyclic shift factor, the quantity Nidx,Kof elements included in the first frequency domain position set Kidx, and the quantity Nidx,Tof elements included in the first time domain position set Tidx, there may be NF×NT×Nidx,K×Nidx,Tdifferent combinations, that is, NF×NT×Nidx,K×Nidx,Tantenna ports can be supported. It can be learned that a capacity of reference signals can be significantly increased in the solution provided in this embodiment of this application.

In the foregoing embodiment, lengths of the N symbols included in the resource unit are the same, in other words, subcarrier spacings of the N symbols included in the resource unit are the same.

In another implementation, when N>Nrsis met, duration of each of the Nrssymbols used to carry second reference signal sequences is different from duration of each of the other (N−Nrs) symbols of the N symbols.

Herein, the other (N−Nrs) symbols are remaining symbols obtained by excluding the Nrssymbols from the N symbols included in the resource unit.

For example, the N symbols are OFDM symbols or SC-FDMA symbols, and a subcarrier spacing of the Nrssymbols used to carry second reference signal sequences is different from a subcarrier spacing of the other (N−Nrs) symbols. The subcarrier spacing of the Nrssymbols used to carry second reference signal sequences may be P times of the subcarrier spacing of the other (N−Nrs) symbols, where P is a positive integer greater than 1. In addition, a quantity of subcarriers included in each of the Nrssymbols used to carry second reference signal sequences is 1/P of a quantity of subcarriers included in each of the other (N−Nrs) symbols. In this case, it can be learned that the duration of each of the Nrssymbols used to carry second reference signal sequences is 1/P of the duration of each of the other (N−Nrs) symbols.

For example, assuming that duration of a resource unit is 1 ms, when subcarrier spacings of N symbols included in the resource unit are the same, as shown inFIG.5, the resource unit includes 14 symbols, a subcarrier spacing of each symbol is 15 kHz, and duration of each symbol is approximately 66.66 μs, without considering a cyclic prefix (cyclic prefix, CP). InFIG.5, Nrs=4, and N−Nrs=10.

When a subcarrier spacing of the Nrssymbols used to carry second reference signal sequences is twice (P=2) a subcarrier spacing of the other (N−Nrs) symbols of the N symbols, the subcarrier spacing of the Nrssymbols is 30 kHz, where duration of each of the Nrssymbols is approximately 33.33 μs; and the subcarrier spacing of the other (N−Nrs) symbols is 15 kHz, where duration of each of the other (N−Nrs) symbols is approximately 66.66 μs. It can be learned that duration of two symbols with a subcarrier spacing of 30 kHz is the same as duration of one symbol with a subcarrier spacing of 15 kHz. Therefore, a quantity N of symbols in a 1 ms resource unit may be 18, Nrs=8, and N−Nrs=10.

It can be learned that, when the subcarrier spacing of the Nrssymbols used to carry second reference signal sequences is different from the subcarrier spacing of the other (N−Nrs) symbols, compared with the case in which the subcarrier spacings of the N symbols are the same, a quantity (namely, a value of Nrs) of symbols for carrying second reference signal sequences can be increased, so that a capacity of second reference signal sequences is increased. In addition, in a high-speed moving scenario, a quantity of symbols for carrying second reference signal sequences is increased, so that a channel change can be more accurately tracked, thereby improving demodulation performance.

The foregoing describes in detail the reference signal sending method provided in this application. The following describes a communication apparatus provided in this application.

FIG.10is a schematic block diagram of a communication apparatus according to this application. As shown inFIG.10, the communication apparatus1000includes a processing unit1100, a receiving unit1200, and a sending unit1300.

The processing unit1100is configured to obtain a frequency-domain cyclic shift factor and a time-domain cyclic shift factor, where the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are used to perform phase rotation on a reference signal sequence.

The processing unit1100is further configured to generate a second reference signal sequence based on a first reference signal sequence, the frequency-domain cyclic shift factor, and the time-domain cyclic shift factor.

The sending unit1300is configured to send the second reference signal sequence on an antenna port p, where p∈{0, 1, . . . , P−1}, and P is an integer greater than or equal to 1.

Optionally, in an embodiment, the processing unit1100is configured to:

generate Nrssecond reference signal sequences in a second reference signal sequence set based on the first reference signal sequence, the frequency-domain cyclic shift factor, and the time-domain cyclic shift factor, where the first reference signal sequence and each second reference signal sequence each include Mrselements, Nrs>1 and is an integer, and Mrs>1 and is an integer; and perform phase rotation on an element m of the first reference signal sequence by using ej·αF·mand ej·αT·t, to obtain an element m of a second reference signal sequence t in the second reference signal sequence set, where 0≤m<Mrs, 0≤t<Nrs, αFis the frequency-domain cyclic shift factor, c is the time-domain cyclic shift factor, j indicates an imaginary unit, and both m and t are integers.

Optionally, in an embodiment, the sending unit1300is configured to:

send, in one resource unit, the Nrssecond reference signal sequences included in the second reference signal sequence set, where the resource unit includes N symbols in time domain, each symbol includes M subcarriers in frequency domain, the Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols, each second reference signal sequence is mapped to one of the N symbols, each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols, N≥Nrs, M≥Mrs, and both N and M are positive integers.

Optionally, in an embodiment, the resource unit includes one slot in time domain, the slot includes N symbols, and each symbol includes M subcarriers in frequency domain.

The Nrssymbols are arranged at equal intervals based on a first value width in the N symbols, and/or the Mrssubcarriers are arranged at equal intervals based on a second value width in the M subcarriers included in each symbol of the slot, where the first value width KTmeets the following formula: KT=N/Nrs, the second value width KFmeets the following formula: KF=M/Mrs, and KTand KFare positive integers.

Optionally, in an embodiment, the resource unit includes S slots in time domain, each slot includes N/S symbols, each symbol includes the M subcarriers in frequency domain, and N/S is an integer.

The Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols included in the S slots, and each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols.

Optionally, in an embodiment, each of P antenna ports included in the set {0, 1, . . . , P−1} corresponds to a combination of one value of the frequency-domain cyclic shift factor and one value of the time-domain cyclic shift factor. When a value, corresponding to each antenna port, of the frequency-domain cyclic shift factor is uniquely determined, a value, corresponding to the antenna port, of the time-domain cyclic shift factor is also uniquely determined. Combinations, corresponding to any two of the P antenna ports, of values of the frequency-domain cyclic shift factor and values of the time-domain cyclic shift factor are different.

Optionally, in an embodiment, the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are respectively expressed by using the following formulas:

αFis the frequency-domain cyclic shift factor, NFis an integer, βFis an integer, a value range of βFis [0, NF−1], αT, is the time-domain cyclic shift factor, NTis an integer, βTis an integer, and a value range of βTis [0, NT−1].

In the foregoing implementations, the receiving unit1200and the sending unit1300may be alternatively integrated into one transceiver unit that has both a receiving function and a sending function. This is not limited herein.

Optionally, in an example, the communication apparatus1000may be the transmit end in the method embodiments. In this case, the receiving unit1200may be a receiver, and the sending unit1300may be a transmitter. The receiver and the transmitter may be alternatively integrated into one transceiver.

Optionally, in another example, the communication apparatus1000may be a chip or an integrated circuit mounted in the transmit end. In this case, the receiving unit1200and the sending unit1300may be communication interfaces or interface circuits. For example, the receiving unit1200is an input interface or an input circuit, and the sending unit1300is an output interface or an output circuit.

In the examples, the processing unit1100is configured to perform processing and/or operations implemented inside the transmit end other than a sending or receiving action.

Optionally, the processing unit1100may be a processing apparatus. A function of the processing apparatus may be implemented by hardware, or may be implemented by hardware executing corresponding software. For example, the processing apparatus may include at least one processor and at least one memory. The at least one memory is configured to store a computer program. The at least one processor reads and executes the computer program stored in the at least one memory, so that the communication apparatus1000performs the operations and/or the processing performed by the transmit end in the method embodiments.

Optionally, the processing apparatus may include only a processor, and a memory configured to store a computer program is located outside the processing apparatus. The processor is connected to the memory by using a circuit or a wire, to read and execute the computer program stored in the memory.

In some examples, the processing apparatus may be alternatively a chip or an integrated circuit. For example, the processing apparatus includes a processing circuit or a logic circuit and an interface circuit. The interface circuit is configured to receive a signal and/or data, and transmit the signal and/or the data to the processing circuit, and the processing circuit processes the signal and/or the data, so that the operations and/or the processing performed by the transmit end in the method embodiments are performed.

FIG.11is a schematic block diagram of another communication apparatus according to this application. As shown inFIG.11, the communication apparatus2000includes a processing unit2100, a receiving unit2200, and a sending unit2300.

The processing unit2100is configured to obtain a frequency-domain cyclic shift factor and a time-domain cyclic shift factor, where the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are used to perform phase rotation on a reference signal sequence.

The receiving unit2200is configured to receive a second reference signal sequence from an antenna port p of a transmit end, where p∈{0, 1, . . . , P−1}, and P is an integer greater than or equal to 1.

The processing unit2100is configured to demodulate the second reference signal sequence based on the frequency-domain cyclic shift factor and the time-domain cyclic shift factor.

Optionally, in an embodiment, the processing unit2100is configured to:

demodulate Nrssecond reference signal sequences in a second reference signal sequence set based on the frequency-domain cyclic shift factor and the time-domain cyclic shift factor, where

an element m of a second reference signal sequence t in the second reference signal sequence set is obtained by performing phase rotation on an element m of a first reference signal sequence by using ej·αF·mand ej·αT·t, the first reference signal sequence and each second reference signal sequence each include Mrselements, Nrs≥1 and is an integer, Mrs≥1 and is an integer, 0≤m<Mrs, 0≤t<Nrs, αFis the frequency-domain cyclic shift factor, αTis the time-domain cyclic shift factor, j indicates an imaginary unit, and both m and t are integers.

Optionally, in an embodiment, the receiving unit2200is configured to:

receive the Nrssecond reference signal sequences that are included in the second reference signal sequence set in one resource unit and that come from the antenna port p of the transmit end, where the resource unit includes N symbols in time domain, each symbol includes M subcarriers in frequency domain, the Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols, each second reference signal sequence is mapped to one of the N symbols, each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols, N≥Nrs, M≥Mrs, and both N and M are positive integers.

Optionally, in an embodiment, the resource unit includes one slot in time domain, the slot includes N symbols, and each symbol includes M subcarriers in frequency domain.

The Nrssymbols are arranged at equal intervals based on a first value width in the N symbols, and/or the Mrssubcarriers are arranged at equal intervals based on a second value width in the M subcarriers included in each symbol of the slot, where the first value width KTmeets the following formula: KT=N/Nrs, the second value width KFmeets the following formula: KF=M/Mrs, and KTand KFare positive integers.

Optionally, in an embodiment, the resource unit includes S slots in time domain, each slot includes N/S symbols, each symbol includes the M subcarriers in frequency domain, and N/S is an integer.

The Nrssecond reference signal sequences are mapped to Nrssymbols of the N symbols included in the S slots, and each second reference signal sequence is mapped to Mrssubcarriers of one of the Nrssymbols.

Optionally, in an embodiment, each of P antenna ports included in the set {0,1, P—1} corresponds to a combination of one value of the frequency-domain cyclic shift factor and one value of the time-domain cyclic shift factor. When a value, corresponding to each antenna port, of the frequency-domain cyclic shift factor is uniquely determined, a value, corresponding to the antenna port, of the time-domain cyclic shift factor is also uniquely determined. Combinations, corresponding to any two of the P antenna ports, of values of the frequency-domain cyclic shift factor and values of the time-domain cyclic shift factor are different.

Optionally, in an embodiment, the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are respectively expressed by using the following formulas:

where

αFis the frequency-domain cyclic shift factor, NFis an integer, βFis an integer, a value range of βFis [0, NF−1], αT, is the time-domain cyclic shift factor, NTis an integer, βTis an integer, and a value range of βTis [0, NT−1].

In the foregoing implementations, the receiving unit2200and the sending unit2300may be alternatively integrated into one transceiver unit that has both a receiving function and a sending function. This is not limited herein.

Optionally, in an example, the communication apparatus2000may be the receive end in the method embodiments. In this case, the receiving unit2200may be a receiver, and the sending unit2300may be a transmitter. The receiver and the transmitter may be alternatively integrated into one transceiver.

Optionally, in another example, the communication apparatus2000may be a chip or an integrated circuit mounted in the receive end. In this case, the receiving unit2200and the sending unit2300may be communication interfaces or interface circuits. For example, the receiving unit2200is an input interface or an input circuit, and the sending unit2300is an output interface or an output circuit.

In the examples, the processing unit2100is configured to perform processing and/or operations implemented inside the receive end other than a sending or receiving action.

Optionally, the processing unit2100may be a processing apparatus. A function of the processing apparatus may be implemented by hardware, or may be implemented by hardware executing corresponding software. For example, the processing apparatus may include at least one processor and at least one memory. The at least one memory is configured to store a computer program. The at least one processor reads and executes the computer program stored in the at least one memory, so that the communication apparatus2000performs the operations and/or the processing performed by the receive end in the method embodiments.

Optionally, the processing apparatus may include only a processor, and a memory configured to store a computer program is located outside the processing apparatus. The processor is connected to the memory by using a circuit or a wire, to read and execute the computer program stored in the memory.

Optionally, in some examples, the processing apparatus may be alternatively a chip or an integrated circuit. For example, the processing apparatus includes a processing circuit or a logic circuit and an interface circuit. The interface circuit is configured to receive a signal and/or data, and transmit the signal and/or the data to the processing circuit, and the processing circuit processes the signal and/or the data, so that the operations performed by the receive end in the method embodiments are performed.

FIG.12is a schematic diagram of a structure of a communication apparatus according to this application. As shown inFIG.12, the communication apparatus10includes one or more processors11, one or more memories12, and one or more communication interfaces13. The processor11is configured to control the communication interface13to send or receive a signal. The memory12is configured to store a computer program. The processor11is configured to invoke the computer program from the memory12and run the computer program, so that the processes and/or the operations performed by the transmit end in the method embodiments of this application are performed.

For example, the processor11may have a function of the processing unit1100shown inFIG.10, and the communication interface13may have a function of the receiving unit1200and/or the sending unit1300shown inFIG.10. The processor11may be configured to perform the processing or the operations performed by the transmit end inFIG.1toFIG.9, and the communication interface13is configured to perform the sending action and/or the receiving action performed by the transmit end inFIG.1toFIG.9.

In an implementation, the communication apparatus10may be the transmit end in the method embodiments. In this implementation, the communication interface13may be a transceiver. The transceiver may include a receiver and a transmitter. Optionally, the processor11may be a baseband apparatus, and the communication interface13may be a radio frequency apparatus. In another implementation, the communication apparatus10may be a chip or an integrated circuit mounted in the transmit end. In this implementation, the communication interface13may be an interface circuit or an input/output interface.

FIG.13is a schematic diagram of a structure of another communication apparatus according to this application. As shown inFIG.13, the communication apparatus20includes one or more processors21, one or more memories22, and one or more communication interfaces23. The processor21is configured to control the communication interface23to send or receive a signal. The memory22is configured to store a computer program. The processor21is configured to invoke the computer program from the memory22and run the computer program, so that the processes and/or the operations performed by the receive end in the method embodiments of this application are performed.

For example, the processor21may have a function of the processing unit2100shown inFIG.11, and the communication interface23may have a function of the receiving unit2200and/or the sending unit2300shown inFIG.11. The processor21may be configured to perform the processing or the operations performed by the receive end inFIG.1toFIG.9, and the communication interface33is configured to perform the sending action and/or the receiving action performed by the receive end inFIG.1toFIG.9.

In an implementation, the communication apparatus20may be the receive end in the method embodiments. In this implementation, the communication interface23may be a transceiver. The transceiver may include a receiver and a transmitter. Optionally, the processor21may be a baseband apparatus, and the communication interface23may be a radio frequency apparatus. In another implementation, the communication apparatus20may be a chip or an integrated circuit mounted in the receive end. In this implementation, the communication interface23may be an interface circuit or an input/output interface.

Optionally, the memory and the processor in the foregoing apparatus embodiments may be physically independent units, or the memory and the processor may be integrated together. This is not limited in this specification.

In addition, this application further provides a computer-readable storage medium. The computer-readable storage medium stores computer instructions. When the computer instructions are run on a computer, the operations and/or the processes performed by the transmit end in the method embodiments of this application are performed.

This application further provides a computer-readable storage medium. The computer-readable storage medium stores computer instructions. When the computer instructions are run on a computer, the operations and/or the processes performed by the receive end in the method embodiments of this application are performed.

In addition, this application further provides a computer program product. The computer program product includes computer program code or instructions. When the computer program code or the instructions are run on a computer, the operations and/or the processes performed by the transmit end in the method embodiments of this application are performed.

This application further provides a computer program product. The computer program product includes computer program code or instructions. When the computer program code or the instructions are run on a computer, the operations and/or the processes performed by the receive end in the method embodiments of this application are performed.

In addition, this application further provides a chip. The chip includes a processor. A memory configured to store a computer program is disposed separately from the chip. The processor is configured to execute the computer program stored in the memory, so that a transmit end in which the chip is mounted performs the operations and/or the processing performed by the transmit end in any method embodiment.

Further, the chip may further include a communication interface. The communication interface may be an input/output interface, an interface circuit, or the like. Further, the chip may further include the memory.

This application further provides a chip. The chip includes a processor. A memory configured to store a computer program is disposed separately from the chip. The processor is configured to execute the computer program stored in the memory, so that a receive end on which the chip is mounted performs the operations and/or the processing performed by the receive end in any method embodiment.

Further, the chip may further include a communication interface. The communication interface may be an input/output interface, an interface circuit, or the like. Further, the chip may further include the memory.

In addition, this application further provides a communication apparatus (which may be, for example, a chip), including a processor and a communication interface. The communication interface is configured to receive a signal and transmit the signal to the processor. The processor processes the signal, so that the operations and/or the processing performed by the transmit end in any method embodiment are performed.

When the communication apparatus is a chip, the chip is configured to generate the second reference signal sequence, and a communication apparatus in which the chip is mounted can be enabled to perform the operation of sending a reference signal in embodiments of this application.

This application further provides a communication apparatus (which may be, for example, a chip), including a processor and a communication interface. The communication interface is configured to receive a signal and transmit the signal to the processor. The processor processes the signal, so that the operations and/or the processing performed by the receive end in any method embodiment are performed.

When the communication apparatus is a chip, the chip is configured to generate the second reference signal sequence, and a communication apparatus in which the chip is mounted can be enabled to perform the operation of receiving a reference signal in embodiments of this application.

In addition, this application further provides a communication apparatus, including at least one processor. The at least one processor is coupled to at least one memory. The at least one processor is configured to execute a computer program or instructions stored in the at least one memory, so that the operations and/or the processing performed by the transmit end in any method embodiment are performed.

This application further provides a communication apparatus, including at least one processor. The at least one processor is coupled to at least one memory. The at least one processor is configured to execute a computer program or instructions stored in the at least one memory, so that the operations and/or the processing performed by the receive end in any method embodiment are performed.

In addition, this application further provides a communication device, including a processor, a memory, and a transceiver. The memory is configured to store a computer program. The processor is configured to invoke the computer program stored in the memory and run the computer program, and control the transceiver to send or receive a signal, so that a transmit end performs the operations and/or the processing performed by the transmit end in any method embodiment.

This application further provides a communication device, including a processor, a memory, and a transceiver. The memory is configured to store a computer program. The processor is configured to invoke the computer program stored in the memory and run the computer program, and control the transceiver to send or receive a signal, so that a receive end performs the operations and/or the processing performed by the receive end in any method embodiment.

In addition, this application further provides a wireless communication system, including the transmit end and the receive end in embodiments of this application.

Optionally, in uplink transmission, the transmit end is a terminal device, and the receive end is a network device; and in downlink transmission, the transmit end is a network device, and the receive end is a terminal device.

In addition, function units in embodiments of this application may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

The term “and/or” in this application describes only an association relationship for describing associated objects and represents that there may be three relationships. For example, A and/or B may represent the following three cases: Only A exists, both A and B exist, and only B exists. A, B, and C may be singular or plural. This is not limited.

In embodiments of this application, the numbers such as “first” and “second” are used to distinguish between same items or similar items that have a basically same function and effect. A person skilled in the art can understand that the “first” and the “second” are not intended to limit a quantity or a sequence, and the “first”, the “second”, and the like do not mean being definitely different either.