Patent Description:
<CIT> describes trhat a mapping unit that provides a frequency allocation that is different for each of transmit antennas; and a reference signal generator that determines a reference signal sequence for each of the transmit antennas so that the same sequence is transmitted from the transmit antennas with each frequency after the mapping by the mapping unit.

In a wireless communication system, a reference signal (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 (channel estimation, CE) on a channel of the transmit end may also be referred to as a demodulation reference signal (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 (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 (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 (overhead) 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.

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

Appended claim <NUM> defines a reference signal sending method. Appended claim <NUM> defines a reference signal receiving method. Appended cloaim <NUM> defines a communication apparatus. Appended claim <NUM> defines a computer-readable storage medium. Appended claim <NUM> defines a computer program product. Appended claim <NUM> defines a communication system. The invention and its scope of protection is defined by these independent claims. The following aspects and implementations of the summary provide examples of combinations of technical subject matters.

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.

Technical solutions of this application are applicable to the following communication systems, including but not limited to a narrowband internet of things (narrow band-internet of things, NB-IoT) system, a global system for mobile communications (global system for mobile communications, GSM), an enhanced data rate for GSM evolution (enhanced data rate for GSM evolution, EDGE) system, a wideband code division multiple access (wideband code division multiple access, WCDMA) system, a code division multiple access <NUM> (code division multiple access, CDMA2000) system, a time division-synchronization code division multiple access (time division-synchronization code division multiple access, TD-SCDMA) system, a long term evolution (long term evolution, LTE) system, three application scenarios of a fifth generation (the <NUM>th generation, <NUM>) 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 (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 (3rd generation, <NUM>) system, the base station is referred to as a NodeB (NodeB); in an LTE system, the base station is referred to as an evolved NodeB (evolved NodeB, eNB or eNodeB); and in a <NUM> system, the base station is referred to as a next generation NodeB (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 (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 specifically user equipment (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 (machine type communication, MTC) device, a terminal device in a <NUM> network or a future communication network, or the like. The terminal device is also referred to as user equipment (user equipment, UE), a terminal, or the like.

<FIG> shows an example of an architecture of a communication system to which an embodiment of this application is applicable. As shown in <FIG>, the communication system includes one or more network devices (for example, <NUM> in <FIG>). The network device <NUM> communicates with one or more terminal devices, for example, terminal devices <NUM> and <NUM> in <FIG>. It should be understood that only one network device <NUM> and two terminal devices <NUM> and <NUM> are used as examples in <FIG>, 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> is a schematic flowchart of a reference signal sending method according to this application. Optionally, the process shown in <FIG> may 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.

<NUM>: 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.

<NUM>: 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 Mrs may be generated by using the following formulas: <MAT> <MAT> where
xq may 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 <NUM> mod <NUM> is <NUM>; NZC may be the largest prime number less than Mrs; and usually, q and Nzc are 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 (binary phase shift keying, BPSK), quadrature phase shift keying (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 <NUM> in the section <NUM>. <NUM> 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: <MAT> where
A is a constant, and may be specifically a real number, an imaginary number, or a complex number. For example, <MAT>.

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: <MAT> where
r<NUM>(m) indicates an element m of the first reference signal sequence, and r<NUM>,t(m) indicates an element m of a second reference signal sequence t in the second reference signal sequence set.

In addition, Mrs is 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 Nrs is a quantity of second reference signal sequences included in the second reference signal sequence set, where Mrs and Nrs are 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 <NUM>.

When the quantity of first reference signal sequences included in the first reference signal sequence set is greater than <NUM>, 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 <NUM>, the second reference signal sequence may be generated by using the following formula: <MAT> where
r<NUM>,t(m) indicates an element m of a first reference signal sequence t in the first reference signal sequence set, r<NUM>,t(m) indicates the element m of the second reference signal sequence t in the second reference signal sequence set, Nrs is 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 Mrs is 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 (<NUM>) or the formula (<NUM>), 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 M<NUM>,rs, and a length of the second reference signal sequence is denoted as M<NUM>,rs, where M<NUM>,rs, and M<NUM>,rs are positive integers.

In this implementation, the second reference signal sequence may be generated by using the following formula: <MAT> where
Δ is an offset, and Δ is an integer, and may be predefined.

It can be learned according to the formula (<NUM>) that the element m (namely, r<NUM>,t(m)) of the second reference signal sequence t in the second reference signal sequence set is obtained by performing phase rotation on an element (m+Δ)modM<NUM>,rs of the first reference signal sequence by using ej·αF·m and ej·αT·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, αF and αT may be respectively determined by using the following formulas: <MAT> where
NF is an integer, βF is an integer, and a value range of βF is [<NUM>, NF - <NUM>]; and <MAT> where
NT is an integer, βT is an integer, and a value range of βT is [<NUM>, NT - <NUM>].

Optionally, in an example, βF and βT may be configured by the receive end for the transmit end through indication by using signaling. It can be learned that, when a value of βF is any integer ranging from <NUM> to NF - <NUM>, a minimum quantity of bits of signaling used by the receive end to indicate βF is <MAT>. Likewise, when a value of βT is any integer ranging from <NUM> to NT - <NUM>, a minimum quantity of bits of signaling used by the receive end to indicate βT is <MAT>, where ┌ ┐ indicates rounding up.

Optionally, the value of βF may be alternatively some values ranging from <NUM> to NF - <NUM>. For example, when a value of NF is <NUM>, the value of βF may be values <NUM>, <NUM>, <NUM>, and <NUM> in <NUM> to <NUM>. In this case, the value of βF may be indicated by using <NUM>-bit signaling. Values indicated by the <NUM>-bit signaling are <NUM> to <NUM>, and are in a one-to-one correspondence with four possible values of βF : <NUM>, <NUM>, <NUM>, and <NUM>. For example, the value <NUM> indicated by the <NUM>-bit signaling corresponds to the value <NUM> of βF, the value <NUM> indicated by the signaling corresponds to the value <NUM> of βF, the value <NUM> indicated by the signaling corresponds to the value <NUM> of βF, and the value <NUM> indicated by the signaling corresponds to the value <NUM> of βF.

Optionally, the value of βT may be alternatively some values ranging from <NUM> to NT - <NUM>. For example, when a value of NT is <NUM>, the value of βT may be values <NUM>, <NUM>, <NUM>, and <NUM> in <NUM> to <NUM>. In this case, the value of βT may be indicated by using <NUM>-bit signaling. Values indicated by the <NUM>-bit signaling are <NUM> to <NUM>, and are in a one-to-one correspondence with four possible values of βT : <NUM>, <NUM>, <NUM>, and <NUM>. For example, the value <NUM> indicated by the <NUM>-bit signaling corresponds to the value <NUM> of βT, the value <NUM> indicated by the signaling corresponds to the value <NUM> of βT, the value <NUM> indicated by the signaling corresponds to the value <NUM> of βT, and the value <NUM> indicated by the signaling corresponds to the value <NUM> of βT.

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

In the predefined manner, the value of NF may be <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like; or the value of NF may be a quantity of subcarriers included in one resource block (resource block, RB), for example, <NUM>.

For example, <MAT>, NF = <NUM>, and the value of βF is any integer ranging from <NUM> to NF - <NUM>. A valueof αF may be <NUM>, <MAT>, π, <MAT>, or <MAT>.

Likewise, in the predefined manner, the value of NT may be <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like; or the value of NT may be determined by the quantity Nrs of second reference signal sequences, for example, NT = Nrs, NT = <MAT>, or <MAT>, where K is a positive integer greater than <NUM>. For example, K = <NUM>. Particularly, when Nrs/K is an integer, the value of NT is as follows: NT = Nrs/K.

For example, <MAT>, and <MAT>. It can be learned that the first reference signal sequence t, namely, r<NUM>,t, in the first reference signal sequence set and the second reference signal sequence t, namely, r<NUM>,t, in the second reference signal sequence set meet the following formula: <MAT>.

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 αF and the time-domain cyclic shift factor αT. Different transmit ends have at least one of different αF and 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 (<NUM>) and (<NUM>) that the frequency-domain cyclic shift factor αF may have a maximum of NF values, and the time-domain cyclic shift factor αT may have a maximum of NT values. 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.

It can be learned that the frequency-domain cyclic shift factor αF may have a maximum of NF different values, and the time-domain cyclic shift factor αT may have a maximum of NT different 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 αF and αT. For example, the signaling may be downlink control information (downlink control information, DCI) or higher layer signaling, for example, radio resource control (radio resource control, RRC) signaling.

In this application, it is assumed that values of the frequency-domain cyclic shift factor αF constitute a first set, and values of the time-domain cyclic shift factor αT constitute a second set, where the first set includes N<NUM> elements, the second set includes N<NUM> elements, and N<NUM> and N<NUM> are positive integers.

A frequency-domain cyclic shift factor corresponding to an antenna port po of the P antenna ports is an element i<NUM> in the first set, and a time-domain cyclic shift factor corresponding to the antenna port po is an element i<NUM> in the second set; and.

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

For example, αF is used as an example. Assuming that <MAT>, the value of NF is <NUM>, and the value of βF is <NUM> to <NUM>, αF has a total of eight values: <NUM>, <MAT>, π, <MAT>, or <MAT>. In this case, the value of αF may be indicated by using <NUM>-bit signaling (denoted as iF). Eight different values <NUM> to <NUM> of iF are in a one-to-one correspondence with the eight values of αF respectively, as shown in Table <NUM>.

It should be understood that the one-to-one mapping relationship shown in Table <NUM> is merely used as an example, and the value of αF may include only some values shown in Table <NUM>. In addition, a correspondence between each value indicated by iF and the value of αF is also merely used as an example. For example, in Table <NUM>, when the value of iF is <NUM>, a corresponding value of αF is <NUM>; or when the value of iF is <NUM>, a corresponding value of αF is <NUM>. That is, provided that different values of iF and values of αF meet 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, αT is used as an example. Assuming that <MAT>, the value of NT is <NUM>, and the value of βT is <NUM> to <NUM>, αT has a total of eight values: <NUM>, <MAT>, π, <MAT>, or <MAT>. In this case, the value of αT may be indicated by using <NUM>-bit signaling (denoted as iT). Eight different values <NUM> to <NUM> of iT are in a one-to-one correspondence with the eight values of αT respectively, as shown in Table <NUM>.

Specifically, the values of the frequency-domain cyclic shift factor αF and the time-domain cyclic shift factor αT may be alternatively determined by using a value indicated by same signaling.

For example, assuming that <MAT>, the value of NF is <NUM>, and the value of βF is <NUM> to <NUM>, αF has four different values: <NUM>, <MAT>, π, and <MAT>; or assuming that <MAT>, the value of NT is <NUM>, and the value of βT is <NUM> to <NUM>, αT has two different values: <NUM> and. In this case, the values of αF and αT are determined by using <NUM>-bit signaling (denoted as iTF). In an example for description, a determining manner is shown in Table <NUM>.

It should be noted that the correspondence between iF and αF, the correspondence between iT and αT, and the correspondence between iTF and αF and αT in the foregoing tables are merely examples. Other possible correspondences are not excluded.

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

For example, βF is used as an example. Assuming that <MAT>, the value of NF is <NUM>, and the value of βF is <NUM> to <NUM>. In this case, the value of βF may be indicated by using <NUM>-bit signaling (denoted as iF), and further, the value of αF is determined based on the value of βF. Eight different values <NUM> to <NUM> of iF are in a one-to-one correspondence with the eight values of βF respectively, as shown in Table <NUM>.

For example, αT is used as an example. Assuming that <MAT>, the value of NT is <NUM>, and the value of βT is <NUM> to <NUM>. In this case, the value of βT may be indicated by using <NUM>-bit signaling (denoted as iT), and further, the value of αT is determined based on the value of βT. Eight different values <NUM> to <NUM> of iT are in a one-to-one correspondence with the eight values of βT respectively, as shown in Table <NUM>.

Specifically, the values of βF and βT may be alternatively determined by using a value indicated by same signaling.

For example, it is assumed that <MAT>, the value of NF is <NUM>, and the value of βF is <NUM> to <NUM>; and it is assumed that <MAT>, the value of NT is <NUM>, and the value of βT is <NUM> to <NUM>. In this case, the values of βF and βT are determined by using <NUM>-bit signaling (denoted as iTF), and further, the values of αF and αT may be determined. In an example for description, a determining manner is shown in Table <NUM>.

It can be learned that the values of ej·αF·m and ej·αT·t may be determined based on the values of αF and αT. For example, when the value of αF is <MAT>, based on different values of m, ej·αF·m is obtained by repeating a sequence [<NUM>, j, -<NUM>, -j]. Assuming that <MAT>, it can be learned that NF consecutive elements in ej·αF·m have different values, and there are only NF possible values. Therefore, it can be learned according to the formula (<NUM>) and the formula (<NUM>) that ej·αF·m has NF possible values, and ej·αT·t has NT possible values.

Therefore, an element <NUM> to an element NF - <NUM> in ej·αF·m may be expressed as a sequence WF whose length is NF, and an element <NUM> to an element NT - <NUM> in ej·αT·t may be expressed as a sequence WT whose lengthis NT. In this case, ej·αF·m and ej·αT·t may be expressed as follows: <MAT> <MAT>.

Therefore, ej·αF·m and ej·αT·t may be further determined based on a one-to-one correspondence between the values indicated by the signaling and the sequence WF and 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 NF is <NUM> and the value of NT is <NUM>. In this case, values of the sequence WF and the sequence WT are determined by using <NUM>-bit signaling (denoted as iTF), and further, the valuesof ej·αF·m and ej·αT·t may be determined. NF elements of the sequence WF may be expressed as [WF(<NUM>), WF(<NUM>), WF(<NUM>), WF(<NUM>)]. NT elements of the sequence WT may be expressed as [WT(<NUM>), WT(<NUM>)]. In an example for description, a determining manner is shown in Table <NUM>.

Frequency-domain cyclic shift factors αF and time-domain cyclic shift factors αT of 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 step <NUM>.

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

The antenna port p ∈ {<NUM>, <NUM>,. , P - <NUM>}, and P is an integer greater than or equal to <NUM>.

Specifically, 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 Mrs subcarriers 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 Mrs elements) may be mapped onto the Mrs subcarriers 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 Nrs second reference signal sequences, and the Nrs second reference signal sequences may be sent on Nrs symbols in time domain. The Nrs second reference signal sequences are in a one-to-one correspondence with the Nrs symbols, and each second reference signal sequence is mapped to a corresponding symbol.

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

For example, one resource unit may be one resource block (resource block, 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 > Nrs or M > Mrs is 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 (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 (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 Nrs symbols 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 Mrs subcarriers 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 KT meets the following formula: KT = N/Nrs, and the second value width KF meets the following formula: KF = M/Mrs, where KT and KF are 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 Nrs symbols are arranged at equal intervals based on the first value width in the N symbols, and/or the Mrs subcarriers 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> is used as an example for description below.

<FIG> shows an example of a mapping pattern of second reference signal sequences in one resource unit. As shown in <FIG>, it is assumed that the resource unit includes one slot, the slot includes <NUM> symbols, that is, N = <NUM>, and one symbol includes <NUM> subcarriers, that is, M = <NUM>. A time domain position (also referred to as a time domain index) of a starting symbol of the <NUM> symbols is denoted as tstart, and a frequency domain position (also referred to as a frequency domain index) of a starting subcarrier of the <NUM> subcarriers is denoted as kstart. As shown in <FIG>, a length Mrs of the second reference signal sequence is <NUM>, and a quantity Nrs of second reference signal sequences is <NUM>. 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 <NUM>, in the <NUM> 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 <NUM>, in a corresponding symbol.

As shown in <FIG>, it is assumed that a time domain position set of the Nrs second 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 tidx may be a relative position relative to the time domain position tstart of the starting symbol, and a frequency domain position included in the frequency domain position set kidx may be a relative position relative to the frequency domain position kstart of the starting subcarrier. <FIG> is used as an example, where the time domain position set tidx is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>], and the frequency domain position set kidx is [<NUM>, <NUM>, <NUM>, <NUM>].

In another implementation, a time domain position included in the time domain position set tidx may be an absolute position, and a frequency domain position included in the frequency domain position set kidx may also be an absolute position. <FIG> is still used as an example, where tidx = [tstart, tstart + <NUM>, tstart + <NUM>, tstart + <NUM>, tstart + <NUM>, tstart + <NUM>, tstart + <NUM>], and kidx = [kstart, kstart + <NUM>, kstart + <NUM>, kstart + <NUM>].

The foregoing resource unit may include one slot, and the slot includes <MAT> symbols, where both <MAT> and <MAT> are positive integers, and <MAT> may be known based on an agreement between the transmit end and the receive end. <MAT> may be a minimum quantity of symbols included in one resource unit, and the receive end may notify the transmit end of <MAT> through indication by using signaling.

For example, <MAT> may have four values: <NUM>, <NUM>, <NUM>, and <NUM>. In this case, the receive end may perform indication to the transmit end by using <NUM>-bit signaling. In another case, <MAT> may be alternatively implicitly determined based on the first value width KT in the foregoing descriptions.

In addition, in an example, for different subcarrier spacings, one slot may include different quantities of symbols. Specifically, 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 αT is 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 Ns/ot slots, where Ns/ot is a positive integer, and the receive end may notify the transmit end of Ns/ot through indication by using signaling. In this case, values of elements in the time domain position set tidx span a plurality of slots.

For example, one resource unit includes four slots, each slot includes <NUM> symbols, and symbols <NUM>, <NUM>, <NUM>, and <NUM> of each slot are used to send second reference signal sequences, as shown in <FIG>.

<FIG> shows 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 from <NUM>, and symbols <NUM>, <NUM>, <NUM>, and <NUM> of 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 + <NUM>, tstart + <NUM>,. , and tstart + <NUM>. In this case, the time domain position set tidx is expressed by using phase positions, and tidx = [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>].

For example, the resource unit includes a plurality of slots in time domain. When the Nrs symbols 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 <NUM> symbols, and time domain positions of all symbols in the four slots may be expressed as tstart, tstart + <NUM>, tstart + <NUM>,. , tstart + <NUM>. It is assumed that the Nrs symbols corresponding to the Nrs second reference signal sequences are arranged at equal intervals based on the first value width KT, which is <NUM>, in the N symbols, and a position of a symbol corresponding to a second reference signal sequence <NUM> in the N symbols is <NUM>. In this case, it can be learned that Nrs = <NUM>. The time domain position set tidx is expressed by using relative positions. In this case, tidx = [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>]. It can be learned that time domain positions of symbols, in a slot <NUM> (corresponding to relative positions <NUM> to <NUM>) of the resource unit, for sending second reference signal sequences are <NUM>, <NUM>, <NUM>, and <NUM>; time domain positions of symbols, in a slot <NUM> (corresponding to relative positions <NUM> to <NUM>), for sending second reference signal sequences are <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>; time domain positions of symbols, in a slot <NUM> (corresponding to relative positions <NUM> to <NUM>), for sending second reference signal sequences are <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>; and time domain positions of symbols, in a slot <NUM> (corresponding to relative positions <NUM> to <NUM>), for sending second reference signal sequences are <NUM>, <NUM>, <NUM>, and <NUM>.

For data sent in the resource unit, a possibility is that data generated by using to-be-sent bits corresponding to one transport block (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 (redundancy version, 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 transport block (transport block, 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 Mrs subcarriers, where frequency domain positions corresponding to the Mrs subcarriers are included in a frequency domain position set kidx, and a frequency domain position corresponding to a subcarrier to which an element m, namely, r<NUM>,t(m), of a second reference signal sequence t, namely, r<NUM>,t, in the second reference signal sequence set is mapped is kidx(m).

Nrs second reference signal sequences in the second reference signal sequence set are sent on Nrs symbols, the Nrs symbols are included in N symbols of a resource unit, and a set including time domain positions corresponding to the Nrs symbols 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, r<NUM>,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 <NUM> (N = <NUM>) symbols, time domain indexes of the <NUM> symbols are denoted as <NUM> to <NUM>, and a quantity Nrs of second reference signal sequences is <NUM>. In this case, time domain indexes, in the <NUM> symbols included in the slot, of the four symbols for carrying the second reference signal sequences may be <NUM>, <NUM>, <NUM>, and <NUM>, that is, tidx = [<NUM>, <NUM>, <NUM>, <NUM>]. In addition, frequency domain indexes may be <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, that is, kidx = [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>]. <FIG> shows 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 αF and the time-domain cyclic shift factor αF, to obtain the second reference signal sequence, and sending, by the transmit end, the second reference signal sequence in this application.

With reference to <FIG>, the following describes a process of sending a reference signal sequence and receiving the reference signal sequence in an embodiment of this application.

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

<NUM>: 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 in <FIG>, in step <NUM>, 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.

<NUM>: 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.

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

<NUM>: 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.

<NUM>: 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 multiple input-multiple out (multiple input-multiple out, 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 αT 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 αT corresponding to the antenna ports used by the transmit end are orthogonal.

Specifically, second reference signal sequences sent by the transmit end on Nrs symbols are known to the receive end. The receive end performs channel estimation based on second reference signal sequences actually received on Nrs symbols and the known second reference signal sequences, to obtain a frequency domain channel response of the Nrs symbols. In the following descriptions, a frequency domain channel response of each of the Nrs symbols is denoted as Ht, where <NUM> ≤ t < Nrs, and Ht includes Mrs elements.

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

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 αF and the time-domain cyclic shift factor αF, regions 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 αF and 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. Specifically, 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 αF and the time-domain cyclic shift factor αT of 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.

Specifically, after obtaining the channel response hmatrix(t,m) in delay-Doppler domain, the receive end obtains a processed channel response <MAT> 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 <MAT> 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 <MAT> of 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 <MAT> of the Nrs symbols, 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 step <NUM>.

<NUM>: 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 {<NUM>, <NUM>,. , P - <NUM>}, and P is an integer greater than or equal to <NUM>. 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 αF and 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 αT is also uniquely determined. In other words, when a value, corresponding to each of the P antenna ports, of αT is determined, a value, corresponding to the antenna port, of αF is also uniquely determined. Combinations, corresponding to any two of the P antenna ports, of values of αF and values of αT are different.

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

It can be understood that different values of <MAT> and <MAT> may be used for different antenna ports, and values of <MAT> and <MAT> of 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 αF and 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 αF and 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 <MAT> corresponding to the antenna port p, and the second reference signal sequence t in the second reference signal sequence set <MAT> may be generated by using a formula (<NUM>): <MAT> where
<MAT> indicates an element m of the first reference signal sequence corresponding to the antenna port p, <MAT> 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 <MAT>. In this case, the second reference signal sequence is generated based on the foregoing formula (<NUM>).

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 <MAT> corresponding to the antenna port p. In this case, the second reference signal sequence is generated based on the following formula (<NUM>): <MAT> where
<MAT> indicates an element m of a first reference signal sequence t corresponding to the antenna port p, <MAT> 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 (<NUM>) or formula (<NUM>), refer to the foregoing descriptions. Details are not described again.

In addition, in another embodiment, the transmit end generates a second reference signal sequence r<NUM>,t by using the foregoing formula (<NUM>), and then performs phase rotation on the second reference signal sequence by using the frequency-domain cyclic shift factor (denoted as <MAT>) and the time-domain cyclic shift factor (denoted as <MAT>) that correspond to the antenna port p, to obtain a second reference signal sequence <MAT> of the antenna port p.

Specifically, the second reference signal sequence of the antenna port p belongs to the second reference signal sequence set <MAT> corresponding to the antenna port p. The second reference signal sequence t, namely, <MAT>, of the antenna port p in <MAT> may be generated based on the following formulas (<NUM>) and (<NUM>): <MAT>.

It can be learned according to the formula (<NUM>) that the formula (<NUM>) may be further expanded to obtain the formula (<NUM>):
<MAT>, <NUM> ≤ m < Mrs, <NUM> ≤ t < Nrs, p ∈ {<NUM>, <NUM>,. , P - <NUM>} (<NUM>), where
<MAT> indicates an element m of <MAT>. For r<NUM>,t(m), <MAT>, and <MAT>, refer to the descriptions of r<NUM>,t(m), αF, and αT in the formula (<NUM>) respectively.

In this embodiment, the frequency-domain cyclic shift factor αF and the time-domain cyclic shift factor αT may be configured at a cell level, and values of αF and αT of 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 <MAT>, and the time-domain cyclic shift factor corresponding to the antenna port p is denoted as <MAT>. <MAT> and <MAT> may be respectively determined by using the following formulas: <MAT> where
NF is an integer, <MAT> is an integer, and a value range of <MAT> is <MAT>; and <MAT> where
<MAT> is an integer, <MAT> is an integer, and a value range of <MAT> is <MAT>.

Optionally, in an implementation, <MAT> corresponding to different antenna ports of the P antenna ports may be the same. In this case, <MAT> may be denoted as NF. Alternatively, <MAT> corresponding to different antenna ports may be different.

Likewise, <MAT> corresponding to different antenna ports of the P antenna ports may be the same. In this case, <MAT> may be denoted as NT. Alternatively, <MAT> corresponding to different antenna ports may be different.

For example, values of <MAT>, and <MAT> are the same as the values of αF, NF, and βF defined in the foregoing formula (<NUM>). Likewise, values of <MAT>, and <MAT> may be alternatively the same as the values of αT, NT, and βT defined in the foregoing formula (<NUM>).

For example, values of <MAT> and <MAT> may be alternatively the same as the values of αF and αT listed in Table <NUM> to Table <NUM>.

Different values of <MAT> and <MAT> are 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 <MAT> and <MAT> of 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 <MAT> and different values of <MAT>.

For example, <MAT>, and <MAT>. <MAT> has NF different values, and <MAT> has NT different values. Therefore, a maximum quantity of antenna ports that can be supported is P = NF × NT.

A relationship between <MAT> and <MAT> and the antenna port p may be determined in the following manner.

For example, <MAT> and <MAT> are determined by using the following formulas (<NUM>) and (<NUM>) respectively: <MAT> <MAT> where
mod indicates a modulo operation, a value of p is any integer ranging from <NUM> to P - <NUM>, and ΔF and ΔT are predefined integers, for example, ΔF = <NUM>, or <MAT>, and ΔT = <NUM>, or <MAT>.

For example, <MAT> and <MAT> may be alternatively determined by using the following formulas (<NUM>) and (<NUM>) respectively: <MAT> <MAT> where
mod indicates a modulo operation, and a value of p is any integer ranging from <NUM> to P - <NUM>. In an example, NF = <NUM>, NT = <NUM>, ΔF = <NUM>, and ΔT = <NUM>. In this case, <MAT> and <MAT> are shown in formulas (<NUM>) and (<NUM>) respectively: <MAT> <MAT>.

For example, a correspondence between the antenna port p and a value of <MAT> and a value of <MAT> may be alternatively expressed by using a table. For ease of description, in the following example, assuming that <MAT> corresponding to different antenna ports of the P antenna ports is the same, <MAT> may be denoted as NF in this case; and assuming that <MAT> corresponding to different antenna ports of the P antenna ports is the same, <MAT> may be denoted as NT in this case.

For example, in an example, <MAT> has four different values: <NUM>, <MAT>, π, and <MAT>; and <MAT> has two different values: <NUM> and π. Therefore, eight antenna ports can be supported, and the correspondence between the antenna port p and the value of <MAT> and the value of <MAT> may be shown in Table <NUM>, where p = {<NUM>, <NUM>,.

In another example, <MAT> has four different values: <NUM>, <MAT>, π, and <MAT>; and dj. has three different values: <NUM>, <MAT>, and <MAT>. Therefore, <NUM> antenna ports can be supported, and the correspondence between the antenna port p and the value of <MAT> and the value of <MAT> may be shown in Table <NUM>, where p = {<NUM>, <NUM>,.

In another example, <MAT> has four different values: <NUM>, <MAT>, π, and <MAT>; and <MAT> has four different values: <NUM>, <MAT>, π, and <MAT>. Therefore, <NUM> antenna ports can be supported, and the correspondence between the antenna port p and the value of <MAT> and the value of <MAT> may be shown in Table <NUM>, where p {<NUM>, <NUM>,.

It can be learned from Table <NUM> to Table <NUM> that the antenna port p is in a one-to-one correspondence with the values of <MAT> and <MAT>, and different antenna ports correspond to at least one of different values of <MAT> and different values of <MAT>, 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 <MAT> is in a one-to-one correspondence with the value of <MAT>, and the value of <MAT> is in a one-to-one correspondence with the value of <MAT>. Provided that the values of <MAT> and <MAT> are determined, the values of <MAT> and <MAT> can be determined. Therefore, each of the P antenna ports may also uniquely correspond to a combination of one value of <MAT> and one value of <MAT>, and different antenna ports correspond to at least one of different values of <MAT> and different values of <MAT>.

A correspondence between the antenna port p and a value of <MAT> and a value of <MAT> may be alternatively expressed by using a table.

For example, in an example, the value of NF is <NUM>, <MAT> has four different values: <NUM>, <NUM>, <NUM>, and <NUM>; and the value of NT is <NUM>, and <MAT> has two different values: <NUM> and <NUM>. Therefore, eight antenna ports can be supported, and the correspondence between the antenna port p and the value of <MAT> and the value of <MAT> may be shown in Table <NUM>, where p {<NUM>, <NUM>,.

In another example, the value of NF is <NUM>, <MAT> has four different values: <NUM>, <NUM>, <NUM>, and <NUM>; and the value of NT is <NUM>, and <MAT> has three different values: <NUM>, <NUM>, and <NUM>. Therefore, <NUM> antenna ports can be supported, and the correspondence between the antenna port p and the value of <MAT> and the value of <MAT> may be shown in Table <NUM>, where p {<NUM>, <NUM>,.

In another example, the value of NF is <NUM>, <MAT> has four different values: <NUM>, <NUM>, <NUM>, and <NUM>; and the value of lVT is <NUM>, and <MAT> has four different values: <NUM>, <NUM>, <NUM>, and <NUM>. Therefore, <NUM> antenna ports can be supported, and the correspondence between the antenna port p and the value of <MAT> and the value of <MAT> may be shown in Table <NUM>, where p {<NUM>, <NUM>,.

After the values of <MAT> and <MAT> are determined based on the table, the values of <MAT> and <MAT> may be determined by using the formulas (<NUM>) and (<NUM>).

It can be learned that the values of <MAT> and <MAT> may be determined based on the values of <MAT> and <MAT>. For example, when the value of <MAT> is <MAT>, based on different values of m, <MAT> is obtained by repeating a sequence [<NUM>, j, -<NUM>, j]. <MAT> has NF possible values, and <MAT> has NT possible values.

Therefore, an element <NUM> to an element NF - <NUM> in <MAT> corresponding to the antenna port p may be expressed as a sequence <MAT> whose length is NF, and an element <NUM> to an element NT - <NUM> in <MAT> may be expressed as a sequence <MAT> whose length is NT. In this case, <MAT> and <MAT> may be expressed as follows: <MAT> <MAT>.

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

For example, it is assumed that the value of NF is <NUM> and the value of NT is <NUM>. In this case, values of the sequence <MAT> and the sequence <MAT> may be determined by using <NUM>-bit signaling, and further, the values of <MAT> and <MAT> may be determined. An element NF of the sequence <MAT> may be expressed as <MAT>. An element NT of the sequence <MAT> may be expressed as <MAT>, <MAT>. In an example for description, a determining manner is shown in Table <NUM>.

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 <MAT> and <MAT> are 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, Nrs second reference signal sequences sent by different antenna ports are mapped to same time domain positions and frequency domain positions. In some other embodiments, Nrs second 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.

Specifically, frequency domain positions to which Nrs second reference signal sequences sent by the antenna port p are mapped are included in a frequency domain position set <MAT>, where a frequency domain position corresponding to a subcarrier to which an element m, namely, r<NUM>,t(m), of a second reference signal sequence t, namely, r<NUM>,t, is mapped is <MAT>, and <MAT> includes Mrs elements.

Time domain positions to which the Nrs second reference signal sequences sent by the antenna port p are mapped are included in a time domain position set <MAT>, where a time domain position of a symbol corresponding to the second reference signal sequence t, namely, r<NUM>,t, is <MAT>, and <MAT> includes Nrs elements.

The frequency domain position set <MAT> is an element in a first frequency domain position set Kidx, and the time domain position set <MAT> is 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 Kidx is Nidx,K, where Nidx,K is a positive integer. An element i in the first frequency domain position set Kidx may be denoted as <MAT>, and the element i, namely, <MAT>, includes Mrs values, where a value range of i is [<NUM>, Nidx,K - <NUM>]. 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, <MAT> and <MAT> are different, where i ∈ [<NUM>, Nidx,K - <NUM>], j ∈ [<NUM>, Nidx,K - <NUM>], and a value range of m is [<NUM>, Mrs - <NUM>].

A quantity of elements in the first time domain position set Tidx is Nidx,T, where Nidx,T is a positive integer. An element i in the first time domain position set Tidx may be denoted as <MAT>, and the element i, namely, <MAT>, includes Nrs values. 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, <MAT> and <MAT> are different, where i ∈ [<NUM>, Nidx,T - <NUM>], j ∈ [<NUM>, Nidx,T - <NUM>], and a value range of m is [<NUM>, Nrs - <NUM>].

Frequency domain positions to which Nrs second 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 Kidx includes two elements, that is, Nidx,K = <NUM>. In this case, frequency domain positions to which Nrs second reference signal sequences of an antenna port p<NUM> are mapped, that is, a frequency domain position set <MAT>, may be <MAT>; and frequency domain positions to which Nrs second reference signal sequences of an antenna port p<NUM> are mapped, that is, a frequency domain position set <MAT>, may be <MAT>, where values of p<NUM> and p<NUM> are different, p<NUM> ∈ {<NUM>, <NUM>,. , P - <NUM>}, and p<NUM> ∈ {<NUM>, <NUM>,. , P - <NUM>}.

Time domain positions to which Nrs second 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 Tidx includes two elements, that is, Nidx,T = <NUM>. In this case, time domain positions to which Nrs second reference signal sequences of an antenna port p<NUM> are mapped, that is, a time domain position set <MAT>, may be <MAT>; and time domain positions to which Nrs second reference signal sequences of an antenna port p<NUM> are mapped, that is, a time domain position set <MAT>, may be <MAT>.

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 = <NUM>, and Nidx,K > <NUM>. An example is shown in <FIG> shows an example of time-frequency positions to which second reference signal sequences of antenna ports are mapped. In <FIG>, one resource unit includes one slot, one slot includes <NUM> symbols, that is, N = <NUM>, indexes of the <NUM> symbols are <NUM> to <NUM>, each slot includes <NUM> subcarriers, that is, M = <NUM>, and indexes of the <NUM> subcarriers are <NUM> to <NUM>. It is assumed that Nrs = <NUM> and Mrs = <NUM>, to be specific, there are four second reference signal sequences, and each second reference signal sequence includes six elements. In <FIG>, a first time domain position set Tidx includes one element, and a value <MAT> of the element is [<NUM>, <NUM>, <NUM>, <NUM>]; and a first frequency domain position set Kidx includes two elements, where an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>], and an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>].

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 in <FIG> are merely examples, and may alternatively have other values.

For example, one resource unit includes two slots and a total of <NUM> symbols, and each symbol may include two resource blocks and a total of <NUM> subcarriers. In this case, <MAT>, <MAT> [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>], and <MAT>.

For another example, Nidx,T > <NUM>, and Nidx,K = <NUM>. An example is shown in <FIG> shows an example of time-frequency positions to which second reference signal sequences of antenna ports are mapped. In <FIG>, one resource unit includes one slot, one slot includes <NUM> symbols, that is, N = <NUM>, indexes of the <NUM> symbols are <NUM> to <NUM>, each slot includes <NUM> subcarriers, that is, M = <NUM>, and indexes of the <NUM> subcarriers are <NUM> to <NUM>. It is assumed that Nrs = <NUM> and Mrs = <NUM>, to be specific, there are four second reference signal sequences, and each second reference signal sequence includes six elements. In <FIG>, a first time domain position set Tidx includes two elements, where a value of an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>], and a value of an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>]; and a first frequency domain position set Kidx includes one element, and a value <MAT> of the element is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>].

For another example, Nidx,T > <NUM>, and Nidx,K > <NUM>. An example is shown in <FIG> shows an example of time-frequency positions to which second reference signal sequences of antenna ports are mapped. In <FIG>, one resource unit includes two slots, one slot includes <NUM> symbols, that is, the resource unit includes <NUM> symbols, indexes of the <NUM> symbols are <NUM> to <NUM>, each symbol includes <NUM> subcarriers, that is, M = <NUM>, and indexes of the <NUM> subcarriers are <NUM> to <NUM>. It is assumed that Nrs = <NUM> and Mrs = <NUM>, to be specific, there are seven second reference signal sequences, and each second reference signal sequence includes six elements. In <FIG>, a first time domain position set Tidx includes two elements, where a value of an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>], and a value of an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>]; and a first frequency domain position set Kidx includes two elements, where a value of an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>], and a value of an element <NUM> <MAT> is [<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>].

It can be learned that, when Nrs second 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 Nrs second 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,K of elements included in the first frequency domain position set Kidx and the quantity Nidx,T of elements included in the first time domain position set Tidx, Nidx,K × Nidx,T different 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.

Specifically, 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 NF of values of the frequency-domain cyclic shift factor, the quantity NT of values of the time-domain cyclic shift factor, the quantity Nidx,K of elements included in the first frequency domain position set Kidx, and the quantity Nidx,T of elements included in the first time domain position set Tidx, there may be NF × NT × Nidx,K × Nidx,T different combinations, that is, NF × NT × Nidx,K × Nidx,T antenna 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 > Nrs is met, duration of each of the Nrs symbols 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 Nrs symbols 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 Nrs symbols used to carry second reference signal sequences is different from a subcarrier spacing of the other (N - Nrs) symbols. Specifically, the subcarrier spacing of the Nrs symbols 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 <NUM>. In addition, a quantity of subcarriers included in each of the Nrs symbols used to carry second reference signal sequences is <NUM>/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 Nrs symbols used to carry second reference signal sequences is <NUM>/P of the duration of each of the other (N - Nrs) symbols.

For example, assuming that duration of a resource unit is <NUM>, when subcarrier spacings of N symbols included in the resource unit are the same, as shown in <FIG>, the resource unit includes <NUM> symbols, a subcarrier spacing of each symbol is <NUM>, and duration of each symbol is approximately <NUM>, without considering a cyclic prefix (cyclic prefix, CP). In <FIG>, Nrs = <NUM>, and N - Nrs = <NUM>.

When a subcarrier spacing of the Nrs symbols used to carry second reference signal sequences is twice (P = <NUM>) a subcarrier spacing of the other (N - Nrs) symbols of the N symbols, the subcarrier spacing of the Nrs symbols is <NUM>, where duration of each of the Nrs symbols is approximately <NUM>; and the subcarrier spacing of the other (N - Nrs) symbols is <NUM>, where duration of each of the other (N - Nrs) symbols is approximately <NUM>. It can be learned that duration of two symbols with a subcarrier spacing of <NUM> is the same as duration of one symbol with a subcarrier spacing of <NUM>. Therefore, a quantity N of symbols in a <NUM> resource unit may be <NUM>, Nrs = <NUM>, and N - Nrs = <NUM>.

It can be learned that, when the subcarrier spacing of the Nrs symbols 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> is a schematic block diagram of a communication apparatus according to this application. As shown in <FIG>, the communication apparatus <NUM> includes a processing unit <NUM>, a receiving unit <NUM>, and a sending unit <NUM>.

The processing unit <NUM> is 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 unit <NUM> is 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 unit <NUM> is configured to send the second reference signal sequence on an antenna port p, where p ∈ {<NUM>, <NUM>,. , P - <NUM>}, and P is an integer greater than or equal to <NUM>.

Optionally, in an embodiment, the processing unit <NUM> is specifically configured to:.

Optionally, in an embodiment, the sending unit <NUM> is specifically configured to:
send, in one resource unit, the Nrs second 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 Nrs second reference signal sequences are mapped to Nrs symbols 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 Mrs subcarriers of one of the Nrs symbols, 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 Nrs symbols are arranged at equal intervals based on a first value width in the N symbols, and/or the Mrs subcarriers 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 KT meets the following formula: KT = N/Nrs, the second value width KF meets the following formula: KF = M/Mrs, and KT and KF are 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 Nrs second reference signal sequences are mapped to Nrs symbols of the N symbols included in the S slots, and each second reference signal sequence is mapped to Mrs subcarriers of one of the Nrs symbols.

Optionally, in an embodiment, each of P antenna ports included in the set {<NUM>, <NUM>,. , P - <NUM>} 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: <MAT> where
αF is the frequency-domain cyclic shift factor, NF is an integer, βF is an integer, a value range of βF is [<NUM>, NF - <NUM>], αT is the time-domain cyclic shift factor, NT is an integer, βT is an integer, and a value range of βT is [<NUM>, NT - <NUM>].

In the foregoing implementations, the receiving unit <NUM> and the sending unit <NUM> may 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 apparatus <NUM> may be the transmit end in the method embodiments. In this case, the receiving unit <NUM> may be a receiver, and the sending unit <NUM> may be a transmitter. The receiver and the transmitter may be alternatively integrated into one transceiver.

Optionally, in another example, the communication apparatus <NUM> may be a chip or an integrated circuit mounted in the transmit end. In this case, the receiving unit <NUM> and the sending unit <NUM> may be communication interfaces or interface circuits. For example, the receiving unit <NUM> is an input interface or an input circuit, and the sending unit <NUM> is an output interface or an output circuit.

In the examples, the processing unit <NUM> is configured to perform processing and/or operations implemented inside the transmit end other than a sending or receiving action.

Optionally, the processing unit <NUM> may 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 apparatus <NUM> performs 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> is a schematic block diagram of another communication apparatus according to this application. As shown in <FIG>, the communication apparatus <NUM> includes a processing unit <NUM>, a receiving unit <NUM>, and a sending unit <NUM>.

The receiving unit <NUM> is configured to receive a second reference signal sequence from an antenna port p of a transmit end, where p ∈ {<NUM>, <NUM>,. , P - <NUM>}, and P is an integer greater than or equal to <NUM>.

The processing unit <NUM> is 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 receiving unit <NUM> is specifically configured to:
receive the Nrs second 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 Nrs second reference signal sequences are mapped to Nrs symbols 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 Mrs subcarriers of one of the Nrs symbols, N ≥ Nrs, M ≥ Mrs, and both N and M are positive integers.

Optionally, in an example, the communication apparatus <NUM> may be the receive end in the method embodiments. In this case, the receiving unit <NUM> may be a receiver, and the sending unit <NUM> may be a transmitter. The receiver and the transmitter may be alternatively integrated into one transceiver.

Optionally, in another example, the communication apparatus <NUM> may be a chip or an integrated circuit mounted in the receive end. In this case, the receiving unit <NUM> and the sending unit <NUM> may be communication interfaces or interface circuits. For example, the receiving unit <NUM> is an input interface or an input circuit, and the sending unit <NUM> is an output interface or an output circuit.

In the examples, the processing unit <NUM> is configured to perform processing and/or operations implemented inside the receive end other than a sending or receiving action.

Optionally, the processing unit <NUM> may 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 apparatus <NUM> performs the operations and/or the processing performed by the receive end in the method embodiments.

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> is a schematic diagram of a structure of a communication apparatus according to this application. As shown in <FIG>, the communication apparatus <NUM> includes one or more processors <NUM>, one or more memories <NUM>, and one or more communication interfaces <NUM>. The processor <NUM> is configured to control the communication interface <NUM> to send or receive a signal. The memory <NUM> is configured to store a computer program. The processor <NUM> is configured to invoke the computer program from the memory <NUM> and 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 processor <NUM> may have a function of the processing unit <NUM> shown in <FIG>, and the communication interface <NUM> may have a function of the receiving unit <NUM> and/or the sending unit <NUM> shown in <FIG>. Specifically, the processor <NUM> may be configured to perform the processing or the operations performed by the transmit end in <FIG>, and the communication interface <NUM> is configured to perform the sending action and/or the receiving action performed by the transmit end in <FIG>.

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

<FIG> is a schematic diagram of a structure of another communication apparatus according to this application. As shown in <FIG>, the communication apparatus <NUM> includes one or more processors <NUM>, one or more memories <NUM>, and one or more communication interfaces <NUM>. The processor <NUM> is configured to control the communication interface <NUM> to send or receive a signal. The memory <NUM> is configured to store a computer program. The processor <NUM> is configured to invoke the computer program from the memory <NUM> and 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 processor <NUM> may have a function of the processing unit <NUM> shown in <FIG>, and the communication interface <NUM> may have a function of the receiving unit <NUM> and/or the sending unit <NUM> shown in <FIG>. Specifically, the processor <NUM> may be configured to perform the processing or the operations performed by the receive end in <FIG>, and the communication interface <NUM> is configured to perform the sending action and/or the receiving action performed by the receive end in <FIG>.

In an implementation, the communication apparatus <NUM> may be the receive end in the method embodiments. In this implementation, the communication interface <NUM> may be a transceiver. The transceiver may include a receiver and a transmitter. Optionally, the processor <NUM> may be a baseband apparatus, and the communication interface <NUM> may be a radio frequency apparatus. In another implementation, the communication apparatus <NUM> may be a chip or an integrated circuit mounted in the receive end. In this implementation, the communication interface <NUM> may 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.

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.

The processor in embodiments of this application may be an integrated circuit chip, and has a signal processing capability. In an implementation process, steps in the foregoing method embodiments can be implemented by using a hardware integrated logical circuit in the processor, or by using instructions in a form of software. The processor may be a general-purpose processor, a digital signal processor (digital signal processor, DSP), an application-specific integrated circuit (application-specific integrated circuit, ASIC), a field programmable gate array (field programmable gate array, FPGA) or another programmable logic device, a discrete gate or a transistor logic device, or a discrete hardware component. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor or the like. The steps of the methods disclosed in embodiments of this application may be directly presented as being performed and completed by a hardware encoding processor, or performed and completed by a combination of hardware and a software module in an encoding processor. A software module may be located in a mature storage medium in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an electrically erasable programmable memory, or a register. The storage medium is located in the memory, and a processor reads information in the memory and completes the steps in the foregoing methods in combination with hardware of the processor.

The memory in this embodiment of this application may be a volatile memory or a nonvolatile memory, or may include both a volatile memory and a nonvolatile memory. The non-volatile memory may be a read-only memory (read-only memory, ROM), a programmable read-only memory (programmable ROM, PROM), an erasable programmable read-only memory (erasable PROM, EPROM), an electrically erasable programmable read-only memory (electrically EPROM, EEPROM), or a flash memory. The volatile memory may be a random access memory (random access memory, RAM), used as an external cache. Through example but not limitative description, many forms of RAMs may be used, for example, a static random access memory (static RAM, SRAM), a dynamic random access memory (dynamic RAM, DRAM), a synchronous dynamic random access memory (synchronous DRAM, SDRAM), a double data rate synchronous dynamic random access memory (double data rate SDRAM, DDR SDRAM), an enhanced synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), a synchronous link dynamic random access memory (synchlink DRAM, SLDRAM), and a direct rambus random access memory (direct rambus RAM, DRRAM). It should be noted that the memory of the systems and methods described in this specification includes but is not limited to these and any memory of another proper type.

For example, division into the units is merely logical function division and may be other division in actual implementation.

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. 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.

When the functions are implemented in the form of a software functional unit and sold or used as an independent product, the functions may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of this application essentially, or the part contributing to the conventional technology, or some of the technical solutions may be implemented in a form of a software product. The computer software product is stored in a storage medium, and includes several instructions for instructing a computer device (which may be a personal computer, a server, a network device, or the like) to perform all or some of the steps of the methods described in the embodiments of this application.

Claim 1:
A reference signal sending method, the method being performed by a transmit end and comprising:
obtaining (<NUM>) a frequency-domain cyclic shift factor and a time-domain cyclic shift factor, wherein the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are used to perform phase rotation on a reference signal sequence;
generating (<NUM>) 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
sending (<NUM>) the second reference signal sequence on an antenna port p, wherein p e {<NUM>, <NUM>, ..., P - <NUM>}, and P is an integer greater than or equal to <NUM>;
wherein 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 comprises:
generating Nrs second 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, wherein the first reference signal sequence and each second reference signal sequence each comprise Mrs elements, Nrs ≥ <NUM> and is an integer, and Mrs ≥ <NUM> and is an integer; and
performing phase rotation on an element m of the first reference signal sequence by using ej·αF·m and ej·αT·t, to obtain an element m of a second reference signal sequence t in the second reference signal sequence set, wherein <NUM> ≤ m < Mrs, <NUM> ≤ t < Nrs, αF is the frequency-domain cyclic shift factor, αT is the time-domain cyclic shift factor, j indicates an imaginary unit, and both m and t are integers; and
wherein the frequency-domain cyclic shift factor and the time-domain cyclic shift factor are respectively represented by using the following formulas: <MAT> wherein
αF is the frequency-domain cyclic shift factor, NF is an integer, βF is an integer, a value range of βF is [<NUM>, NF - <NUM>, αT is the time-domain cyclic shift factor, NT is an integer, βT is an integer, and a value range of βT is [<NUM>, NT -<NUM>].