Patent Description:
This application relates to the field of communications technologies, and in particular, to a communication method and apparatus for physical downlink shared channel (PDSCH) transmission.

Currently, <NUM> new radio (new radio, NR) supports spectrum resource sharing with long term evolution (long term evolution, LTE). In <NUM> NR, a symbol occupied by a time domain resource used for PDSCH transmission may dynamically change. For example, a start symbol may be the first symbol or any other symbol in a slot or a subframe, and an end symbol may also be any symbol in the slot or the subframe.

How to configure a time domain position of a demodulation reference signal (de-modulation reference signal, DMRS) on a PDSCH in <NUM> NR, to reduce interference to a cell common signal (e.g. cell-specific reference signal, CRS) in LTE remains to be studied. <CIT> discloses a method for demodulation reference signal (DMRS) transmission. Table <NUM> of the description shows the case of L=<NUM> with two-DMRS position value <NUM>, <NUM> and L=<NUM> with two-DMRS position value <NUM>, <NUM> for one-symbol DMRS of PDSCH mapping type B; table <NUM> of the description shows the case of L=<NUM> with two-DMRS position value <NUM>, <NUM> and L=<NUM> with two-DMRS position value <NUM>, <NUM> for two-symbol DMRS of PDSCH mapping type B. <CIT> also discloses a method for DMRS transmission. Table <NUM> discloses a combination case of PDSCH duration =<NUM> with two-DMRS position value <NUM>, <NUM> for one-symbol DMRS of PDSCH mapping type B and the PDSCH duration=<NUM> with two-DMRS position value <NUM>, <NUM> for one-symbol DMRS of PDSCH mapping type B and a combination case of PDSCH duration=<NUM> with three-DMRS position value <NUM>, <NUM>, <NUM> and PDSCH duration =<NUM> with three-DMRS position value <NUM>, <NUM>, <NUM> for one-symbol DMRS of PDSCH mapping type B. Wherein Table <NUM> discloses a combination of PDSCH duration =<NUM> with two-DMRS position value <NUM>, <NUM> for double-symbol DMRS of PDSCH mapping type B and the PDSCH duration=<NUM> with two-DMRS position value <NUM>, <NUM> for double-symbol DMRS of PDSCH mapping type B.

Embodiments of this application provide a communication method and apparatus, to help reduce mutual interference between a DMRS and a CRS in communication when LTE and NR share a spectrum, and improve transmission performance. The subject matter of this invention is defined by appended claims. The following aspects are described for understanding.

Aspects of the present invention are provided in the independent claims. Preferred embodiments are provided in the dependent claims.

The scope of the present invention is determined by the scope of the appended claims.

In embodiments of this application, "at least one" means one or more, and "a plurality of" means two or more. The term "and/or" describes an association relationship between associated objects and represents that three relationships may exist. For example, A and/or B may represent the following cases: Only A exists, both A and B exist, and only B exists, where A and B may be singular or plural. The character "/" usually represents an "or" relationship between the associated objects. "At least one of the following items (pieces)" or a similar expression thereof indicates any combination of these items, including a single item (piece) or any combination of a plurality of items (pieces). For example, at least one (piece) of a, b, or c may indicate a, b, c, a and b, a and c, b and c, or a, b, and c, where each of a, b, and c may be an element, or may be a set including one or more elements.

In this application, the term "example", "in some embodiments", "in some other embodiments", or the like is used to represent giving an example, an illustration, or a description. Any embodiment or design scheme described as an "example" in this application should not be explained as being more preferred or having more advantages than another embodiment or design scheme. Exactly, the word "example" is used to present a concept in a specific manner.

In this application, "of (of)", "relevant (relevant)", and "corresponding (corresponding)" may be interchangeably used sometimes. It should be noted that meanings expressed by the terms are consistent when differences are not emphasized. In the embodiments of this application, "communication" and "transmission" may be interchangeably used sometimes. It should be noted that meanings expressed by the terms are consistent when differences are not emphasized. For example, transmission may include sending and/or receiving, and may be a noun or a verb.

It should be noted that, in the embodiments of this application, the terms "first", "second" and the like are only used for a purpose of description, and cannot be understood as an indication or implication of relative importance or an indication or implication of a sequence.

The following describes some terms in the embodiments of this application, to facilitate understanding by a person skilled in the art.

In time domain, a time domain position of the first DMRS on the PDSCH is related to a PDSCH mapping type. In NR, the PDSCH mapping type includes a type A (type A) or a type B (type B). For example, a PDSCH is scheduled in a slot i, where i may be a positive integer such as <NUM>, <NUM>, or <NUM>. When the PDSCH mapping type is the type A, in time domain, the time domain position of the first DMRS on the PDSCH may be a symbol <NUM> or a symbol <NUM> in the slot i; and a start symbol of the PDSCH may be a symbol <NUM>, a symbol <NUM>, a symbol <NUM>, or a symbol <NUM> in the slot i, and is usually not located after the time domain position of the first DMRS. In the mapping type, duration of the PDSCH may be a minimum of three symbols, or may be a maximum of <NUM> symbols. When the PDSCH mapping type is the type B, the time domain position of the first DMRS on the PDSCH is a start symbol of the PDSCH; and the start symbol of the PDSCH may be any of a symbol <NUM> to a symbol <NUM> in the slot i, and is related to scheduling of the network device. In the mapping type, duration of the PDSCH may be two symbols, four symbols, seven symbols, nine symbols, <NUM> symbols, or the like.

In addition, different PDSCH mapping types indicate different DMRS patterns. For example, a one-symbol DMRS is used as an example. When the PDSCH mapping type is the type A, if the CDM group number is <NUM> or <NUM>, a pattern in which the DMRS occupies subcarriers on one symbol may be shown in a in <FIG>. It can be learned from a in <FIG> that, when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the symbol are subcarriers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>; or when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the symbol are subcarriers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For another example, a two-symbol DMRS is used as an example. When the PDSCH mapping type is the type A, if the CDM group number is <NUM> or <NUM>, a pattern in which the DMRS occupies subcarriers on two consecutive symbols may be shown in b in <FIG>. It can be learned from b in <FIG> that, when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the two symbols are subcarriers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>; or when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the two symbols are subcarriers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For still another example, a one-symbol DMRS is used as an example. When the PDSCH mapping type is the type B, if the CDM group number is <NUM>, <NUM>, or <NUM>, a pattern in which the DMRS occupies subcarriers on one symbol may be shown in c in <FIG>. It can be learned from c in <FIG> that, when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the symbol are subcarriers <NUM>, <NUM>, <NUM>, and <NUM>; when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the symbol are subcarriers <NUM>, <NUM>, <NUM>, and <NUM>; or when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the symbol are subcarriers <NUM>, <NUM>, <NUM>, and <NUM>. For yet another example, a two-symbol DMRS is used as an example. When the PDSCH mapping type is the type B, if the CDM group number is <NUM>, <NUM> or <NUM>, a pattern in which the DMRS occupies subcarriers on two consecutive symbols may be shown in d in <FIG>. It can be learned from d in <FIG> that, when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the two symbols are subcarriers <NUM>, <NUM>, <NUM>, and <NUM>; when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the two symbols are subcarriers <NUM>, <NUM>, <NUM>, and <NUM>; or when the CDM group number is <NUM>, the subcarriers occupied by the DMRS on the two symbols are subcarriers <NUM>, <NUM>, <NUM>, and <NUM>.

CRS: In LTE, the CRS is used by the terminal device to perform channel estimation, or may be used for downlink channel quality measurement, for example, reference signal received power (reference signal receiving power, RSRP) measurement. After receiving the CRS, the terminal device may perform channel estimation based on the CRS, and demodulate a control channel or a data channel based on a channel estimation result, so that the terminal device obtains control information transmitted on a downlink control channel (physical downlink control channel, PDCCH) or data transmitted on the PDSCH. For example, the network device may send the CRS to the terminal device by using one or more antenna ports, to improve accuracy of channel estimation. Different quantities of antenna ports correspond to CRSs with different patterns. For example, when the quantity of antenna ports is <NUM>, a CRS pattern may be shown in a in <FIG>; when the quantity of antenna ports is <NUM>, a CRS pattern may be shown in b in <FIG>; or when the quantity of antenna ports is <NUM>, a CRS pattern may be shown in c in <FIG>. For an RE used to transmit the CRS, refer to a diagonal filled area.

In addition, an RE actually occupied by the CRS is further related to a shift (shift) value of the CRS. The shift value is equal to a result obtained after a physical cell identifier (identity, ID) of a carrier mod <NUM>. The shift value of the CRS indicates a cyclic shift of a CRS resource in frequency domain. For example, the quantity of antenna ports is <NUM>. When the shift value of the CRS is <NUM>, for an RE actually occupied by the CRS, refer to a diagonal filled area shown in a in <FIG>. For example, the CRS actually occupies the first RE and the seventh RE on the first symbol (namely, the symbol <NUM>). For example, the quantity of antenna ports is <NUM>. When the shift value of the CRS is <NUM>, one subcarrier is cyclically shifted, and REs actually occupied by the CRS on the first symbol are respectively the second RE and the eighth RE. When the quantity of antenna ports is <NUM> or <NUM>, an RE actually occupied by the CRS may also be obtained based on the pattern and the shift value shown in <FIG>.

However, a DMRS pattern and a CRS pattern are usually fixed. Therefore, when NR and LTE share a spectrum resource, if a time domain resource occupied by the DMRS conflicts with a time domain resource occupied by the CRS, mutual interference between the DMRS and the CRS is likely to be caused. In other words, channel estimation or channel quality measurement, such as RSRP measurement, performed when the terminal device receives the CRS in LTE is affected, and channel estimation performed when the terminal device receives the DMRS in NR is also affected. In addition, it should be noted that, when NR and LTE share the spectrum resource, NR and LTE are time-aligned in time domain. For example, a start moment of the slot j in NR is the same as a start moment of the subframe i in LTE, where i may be the same as or different from j. For example, the subframe i is shown in <FIG>, and a start moment of the subframe i is T1; and the slot j is shown in <FIG>, and a start moment of the slot j is T2, where T1 is the same as T2. In this case, NR and LTE are time-aligned in the time domain.

In view of this, this application provides a communication method, so that the network device can indicate an appropriate time domain position of a DMRS on the PDSCH to the terminal device, to reduce a possibility that a time domain resource occupied by the DMRS overlaps a time domain resource occupied by the CRS. Therefore, this helps reduce mutual interference between the DMRS and the CRS and improve communication quality.

The embodiments of this application may be applied to an NR communications system, or may be applied to another communications system, for example, a future mobile communications system (for example, a <NUM> communications system). For example, <FIG> is a schematic diagram of a network architecture of a communications system according to an embodiment of this application. The communications system includes a network device and a terminal device.

It should be noted that, in this embodiment of this application, communication between the network device and the terminal device may be performed by using a licensed spectrum (licensed spectrum), or may be performed by using an unlicensed spectrum (unlicensed spectrum), or may be performed by using both a licensed spectrum and an unlicensed spectrum. This is not limited herein. Communication between the network device and the terminal device and communication between terminal devices may be performed by using a sub-<NUM> gigahertz (gigahertz, GHz) spectrum, or may be performed by using a spectrum above <NUM>, or may be performed by using both a sub-<NUM> spectrum and a spectrum above <NUM>. In other words, this application is applicable to both a low-frequency (for example, sub <NUM>) scenario and a high-frequency (above <NUM>) scenario.

It should be understood that, the network architecture of the communications system shown in <FIG> is merely an example, and constitutes no limitation on the network architecture of the communications system in this embodiment of this application. A quantity of network devices and a quantity of terminal devices in the communications system are not limited in this embodiment of this application. For example, when the communications system in this embodiment of this application includes a plurality of network devices, coordinated multipoint communication may be performed between the network devices. For example, the communications system includes a plurality of macro base stations and a plurality of micro base stations. Coordinated multipoint communication may be performed between the macro base stations, between the micro base stations, or between the macro base station and the micro base station.

The communication method in the embodiments of this application is described in detail by using the network architecture of the communications system shown in <FIG> as an example.

For example, <FIG> is a schematic diagram of a communication method according to an embodiment of this application. The communication method specifically includes the following steps.

<NUM>: A network device sends first indication information to a terminal device. The first indication information is used to indicate a time domain position of a DMRS set on a PDSCH. The DMRS set includes N DMRSs.

A quantity of candidate PDSCHs that meet a first condition in M candidate PDSCHs of the PDSCH is greater than or equal to a first threshold. The first condition is: a time domain position, obtained based on the first indication information, of a candidate DMRS set on the candidate PDSCH does not overlap a time domain position of a CRS set on the candidate PDSCH. N and M are positive integers greater than or equal to <NUM>. The first threshold may be correspondingly set based on an actual situation. For example, the first threshold may be set to <NUM> or <NUM>.

For example, the first indication information may be carried in higher layer signaling, for example, radio resource control (radio resource control, RRC) signaling, and is sent by the network device to the terminal device; or may be carried in another message (for example, a customized message), and is sent by the network device to the terminal device. This is not limited.

<NUM>: The network device sends second indication information to the terminal device. The second indication information is used to indicate a first PDSCH. The first PDSCH is a candidate PDSCH that meets the first condition in the M candidate PDSCHs.

The second indication information may be carried in DCI or another message (for example, a customized message), and is sent by the network device to the terminal device. In addition, the second indication information may alternatively be understood as scheduling information, namely, information used to schedule the terminal device to perform data communication on the first PDSCH.

<NUM>: The terminal device receives the first indication information and the second indication information, and receives, on the first PDSCH based on the first indication information and the second indication information, data sent by the network device.

In some embodiments, a quantity of candidate PDSCHs that meet a second condition in the M candidate PDSCHs is less than or equal to a second threshold. The second condition is: a time domain position, obtained based on the first indication information, of a candidate DMRS set on the candidate PDSCH overlaps a time domain position of a CRS set on the candidate PDSCH.

The following describes this embodiment of this application in detail with reference to an example of a scenario in which LTE and NR share a spectrum resource.

In the scenario in which LTE and NR share a spectrum resource, the DMRS set is used by the terminal device to perform downlink channel estimation in NR, and the CRS set is used by the terminal device to perform downlink channel estimation or channel quality measurement in LTE.

For example, a frame structure parameter corresponding to the DMRS set is a <NUM> subcarrier spacing, and a frame structure parameter corresponding to the CRS set is a <NUM> subcarrier spacing. It should be noted that, that a frame structure parameter corresponding to the DMRS set is a <NUM> subcarrier spacing may be understood as that the <NUM> subcarrier spacing is used in NR, and that a frame structure parameter corresponding to the CRS set is a <NUM> subcarrier spacing may be understood as that the <NUM> subcarrier spacing is used in LTE.

A subframe i shown in <FIG> in LTE is used as an example. A time domain position, on the subframe i, of each CRS in the CRS set may be shown in A in <FIG>. It may be understood that, when the time domain position, on the subframe i, of each CRS in the CRS set may be shown in A in <FIG>, a CRS pattern is a CRS pattern shown in a in <FIG> when a quantity of antenna ports is <NUM>, or a CRS pattern is a CRS pattern shown in b in <FIG> when a quantity of antenna ports is <NUM>. Referring to <FIG>, the subframe i includes <NUM> symbols: a symbol <NUM> to a symbol <NUM>, and a start moment of the subframe i is T1. For example, in NR, a PDSCH is scheduled based on a type B in a slot j. As shown in <FIG>, the slot j includes <NUM> symbols: a symbol <NUM> to a symbol <NUM>, and a start moment of the slot j is T2. T1 and T2 are a same moment.

In an implementation, when a value of N is <NUM>, the DMRS set includes a first DMRS and a second DMRS. The first DMRS and the second DMRS are one-symbol DMRSs. A time domain position of the first DMRS on the PDSCH is a start symbol lo of the PDSCH. In this case, a time domain position of the second DMRS on the PDSCH is a symbol l<NUM>+Δl of the PDSCH. Δl may be understood as a quantity of symbols between a start symbol of the first DMRS and a start symbol of the second DMRS. The start symbol of the first DMRS may be understood as the time domain position of the first DMRS on the PDSCH, and the start symbol of the second DMRS may be understood as the time domain position of the second DMRS on the PDSCH.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. For example, the candidate PDSCH <NUM> is used as an example. If a time domain position of a first DMRS on the candidate PDSCH <NUM> is a symbol <NUM>, a start symbol of the first DMRS is also the symbol <NUM>. If a time domain position of a second DMRS on the candidate PDSCH <NUM> is a symbol <NUM>, a start symbol of the second DMRS is the symbol <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of candidate PDSCHs that meet the second condition is also <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM>, the candidate PDSCH <NUM>, and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of candidate PDSCHs that meet the second condition is <NUM>, and the candidate PDSCH is the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of candidate PDSCHs that meet the second condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM>, the candidate PDSCH <NUM>, the candidate PDSCH <NUM>, and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of candidate PDSCHs that meet the second condition is <NUM>.

As shown in <FIG>, when a <NUM>-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the <NUM>-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the <NUM>-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCH is the candidate PDSCH <NUM>.

For example, a frame structure parameter corresponding to the DMRS set is a <NUM> subcarrier spacing, and a frame structure parameter corresponding to the CRS set is a <NUM> subcarrier spacing.

A subframe i shown in <FIG> in LTE is used as an example. A time domain position, on the subframe i, of each CRS in the CRS set may be shown in A in <FIG>. It may be understood that, when the time domain position, on the subframe i, of each CRS in the CRS set may be shown in A in <FIG>, a CRS pattern is a CRS pattern shown in c in <FIG> when a quantity of antenna ports is <NUM>. Referring to <FIG>, the subframe i includes <NUM> symbols: a symbol <NUM> to a symbol <NUM>, and a start moment of the subframe i is T1. For example, in NR, a PDSCH is scheduled based on a type B in a slot j. As shown in <FIG>, the slot j includes <NUM> symbols: a symbol <NUM> to a symbol <NUM>, and a start moment of the slot j is T2. T1 and T2 are a same moment.

In an implementation, when a value of N is <NUM>, the DMRS set includes a first DMRS and a second DMRS. The first DMRS and the second DMRS are one-symbol DMRSs. A time domain position of the first DMRS on the PDSCH is a start symbol lo of the PDSCH. In this case, a time domain position of the second DMRS on the PDSCH is a symbol l<NUM>+Δl of the PDSCH. Δl may be understood as a symbol interval between a start symbol of the first DMRS and a start symbol of the second DMRS. The start symbol of the first DMRS may be understood as the time domain position of the first DMRS on the PDSCH, and the start symbol of the second DMRS may be understood as the time domain position of the second DMRS on the PDSCH.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCH is the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is also <NUM>, and the PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCH is the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCH is the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCHs are the candidate PDSCH <NUM> and the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCH is the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>.

As shown in <FIG>, when a <NUM>-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the <NUM>-symbol PDSCH are respectively a candidate PDSCH <NUM> and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the <NUM>-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCH is the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCH is the candidate PDSCH <NUM>.

With reference to <FIG> and <FIG>, when the value of N is <NUM>, the frame structure parameter corresponding to the DMRS set is the <NUM> subcarrier spacing, duration L of the PDSCH is <NUM> and <NUM>, and Δl has different values, statistics about the quantity of candidate PDSCHs that meet the first condition are shown in Table <NUM>.

According to Table <NUM>, a value of the first threshold may be set based on an actual situation. For example, the value of the first threshold is <NUM>. For the <NUM> subcarrier spacing, when Δl=<NUM>, the duration L of the PDSCH is nine or <NUM> symbols, and the quantity of antenna ports of the CRS is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to the first threshold. Therefore, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and a symbol lo+<NUM> of the PDSCH in a communications protocol. For example, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and the symbol lo+<NUM> of the PDSCH in the communications protocol in the following manner:.

In this case, for the <NUM> subcarrier spacing, the time domain position, indicated by the first indication information, of the DMRS set on the PDSCH is the start symbol lo of the PDSCH and the symbol l<NUM>+<NUM> of the PDSCH. In this case, a start symbol lo and a symbol lo+<NUM> of the first PDSCH indicated by the second indication information are respectively time domain positions of the DMRSs on the PDSCH.

For another example, the value of the first threshold is <NUM>. For the <NUM> subcarrier spacing, when Δl=<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, the duration L of the PDSCH is <NUM> or <NUM>, and the quantity of antenna ports of the CRS is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to the first threshold. For example, when Δl=<NUM>, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and a symbol lo+<NUM> of the PDSCH in a communications protocol. For example, when Δl=<NUM>, the time domain position of the DMRS set on the PDSCH is defined as the start symbol lo of the PDSCH and a symbol lo+<NUM> of the PDSCH in the communications protocol.

The following uses an example in which the time domain position of the DMRS set on the PDSCH is defined as the start symbol lo of the PDSCH and the symbol lo+<NUM> of the PDSCH in the communications protocol. For example, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and the symbol lo+<NUM> of the PDSCH in the communications protocol in the following manner:.

In addition, in some other embodiments, the duration L of the PDSCH is <NUM> symbols. If the value of the first threshold is <NUM>, for the <NUM> subcarrier spacing, when Δl=<NUM>, and the quantity of antenna ports of the CRS is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to the first threshold. Therefore, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and a symbol lo+<NUM> of the PDSCH in a communications protocol.

For example, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and the symbol lo+<NUM> of the PDSCH in the communications protocol in the following manner:
a PDSCH mapping type being a type B, L being <NUM>, lo being <NUM>, l<NUM>+Δl, and Δl being <NUM>.

In some other embodiments, a second threshold may be further set to further limit the candidate PDSCH, and the time domain position of the DMRS set on the PDSCH is defined based on a value of Δl when both the first condition and the second condition are met.

When a value of N is <NUM>, the DMRS set includes a first DMRS, a second DMRS, and a third DMRS. When the DMRS set corresponds to the <NUM> subcarrier spacing, a time domain position of the first DMRS on the PDSCH is a start symbol lo of the PDSCH, a time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+Δl<NUM> of the PDSCH, and a time domain position of the third DMRS on the PDSCH may be a symbol l<NUM>+Δl<NUM> of the PDSCH. Δl<NUM> is a quantity of symbols between a start symbol of the first DMRS and a start symbol of the second DMRS, and Δl<NUM> is a quantity of symbols between the start symbol of the first DMRS and a start symbol of the third DMRS.

For example, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol lo+<NUM> of the PDSCH. For another example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH.

For another example, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM> and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+<NUM> or a symbol lo+<NUM> of the PDSCH. For another example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol lo+<NUM> of the PDSCH. For another example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH. Alternatively, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol l<NUM>+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH.

Further, considering that there is a relatively small symbol interval between time domain positions of different DMRSs on the PDSCH, reliability of channel estimation may be affected. In some embodiments, when N is <NUM>, it may be defined in a communications protocol that the time domain position of the first DMRS on the PDSCH is a start symbol lo of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol lo+<NUM> or a symbol lo+<NUM> of the PDSCH, and the time domain position of the third DMRS on the PDSCH is a symbol lo+<NUM> or a symbol lo+<NUM> of the PDSCH.

For example, the time domain position of the first DMRS on the PDSCH is the start symbol lo of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, and the time domain position of the third DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, where Δl<NUM>=<NUM> or <NUM>, and Δl<NUM>=<NUM> or <NUM>. For example, the time domain position of the DMRS set on the PDSCH may be defined in the communications protocol in the following manner:.

When a value of N is <NUM>, the DMRS set includes a first DMRS, a second DMRS, a third DMRS, and a fourth DMRS. When the DMRS set corresponds to the <NUM> subcarrier spacing, a time domain position of the first DMRS on the PDSCH is a start symbol lo of the PDSCH, a time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+Δl<NUM> of the PDSCH, a time domain position of the third DMRS on the PDSCH may be a symbol l<NUM>+Δl<NUM> of the PDSCH, and a time domain position of the fourth DMRS on the PDSCH may be a symbol l<NUM>+Δl<NUM> of the PDSCH. Δl<NUM> is a quantity of symbols between a start symbol of the first DMRS and a start symbol of the second DMRS, Δl<NUM> is a quantity of symbols between the start symbol of the first DMRS and a start symbol of the third DMRS, and Δl<NUM> is a quantity of symbols between the start symbol of the first DMRS and a start symbol of the fourth DMRS.

For example, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM> and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol lo+<NUM> of the PDSCH. For another example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the fourth DMRS on the PDSCH may be a symbol lo+<NUM> of the PDSCH. For another example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the fourth DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH.

Further, considering that there is a relatively small symbol interval between time domain positions of different DMRSs on the PDSCH, reliability of channel estimation may be affected. In some embodiments, when N is <NUM>, it may be defined in a communications protocol that the time domain position of the first DMRS on the PDSCH is a start symbol l<NUM> of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol l<NUM>+<NUM> of the PDSCH, the time domain position of the third DMRS on the PDSCH is a symbol l<NUM>+<NUM> of the PDSCH, and the time domain position of the fourth DMRS on the PDSCH is a symbol l<NUM>+<NUM> of the PDSCH; or that the time domain position of the first DMRS on the PDSCH is a start symbol lo of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol lo+<NUM> of the PDSCH, the time domain position of the third DMRS on the PDSCH is a symbol lo+<NUM> of the PDSCH, and the time domain position of the fourth DMRS on the PDSCH is a symbol lo+<NUM> of the PDSCH.

For example, the time domain position of the first DMRS on the PDSCH is the start symbol l<NUM> of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, the time domain position of the third DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, and the time domain position of the fourth DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, where Δl<NUM>=<NUM>, Δl<NUM>=<NUM>, and Δl<NUM>=<NUM>; or Δl<NUM>=<NUM>, Δl<NUM>=<NUM>, and Δl<NUM>=<NUM>. For example, the time domain position of the DMRS set on the PDSCH may be defined in the communications protocol in the following manner:.

It should be noted that, that the <NUM> subcarrier spacing is used in NR, the <NUM> subcarrier spacing is used in LTE, and NR and LTE are time-aligned may be understood as that in NR, a start position of the slot j is aligned with a start position of a slot in the subframe i, For example, the subframe i shown in <FIG> is used as an example. A symbol <NUM> to a symbol <NUM> in the subframe i are a slot <NUM>, and a symbol <NUM> to a symbol <NUM> in the subframe i are a slot <NUM>. As shown in <FIG>, the slot j in NR is used as an example. In this case, the start position of the slot j is aligned with a start position of the slot <NUM>, or the start position of the slot j is aligned with a start position of the slot <NUM>. Both the cases may be understood as that NR and LTE are time-aligned. For example, the start position of the slot j is the moment T2 shown in <FIG>; and the start position of the slot <NUM> is the moment T1 shown in <FIG>. The following uses an example in which T1 and T2 are a same moment for description.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM>, the candidate PDSCH <NUM>, the candidate PDSCH <NUM>, and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM>, the candidate PDSCH <NUM>, and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCH is the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>.

As shown in <FIG>, when a <NUM>-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the <NUM>-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the <NUM>-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM>, the candidate PDSCH <NUM>, and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM> and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM> and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCH is the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCH is the candidate PDSCH <NUM>.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM> and a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>, and the PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>.

As shown in <FIG>, when a <NUM>-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, a candidate PDSCH of the <NUM>-symbol PDSCH is a candidate PDSCH <NUM>. It can be learned from <FIG> that, for the <NUM>-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCH is the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is <NUM>.

According to Table <NUM>, a value of the first threshold may be set based on an actual situation. For example, the value of the first threshold is <NUM>. For the <NUM> subcarrier spacing, when Δl=<NUM>, <NUM>, or <NUM>, the duration L of the PDSCH is nine or <NUM> symbols, and the quantity of antenna ports of the CRS is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to the first threshold. Therefore, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol l<NUM> of the PDSCH and a symbol lo+<NUM>, a symbol l<NUM>+<NUM>, or a symbol l<NUM>+<NUM> of the PDSCH in a communications protocol. For example, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and the symbol lo+<NUM> of the PDSCH in the communications protocol in the following manner:.

In this case, for the <NUM> subcarrier spacing, the time domain position, indicated by the first indication information, of the DMRS set on the PDSCH is the start symbol lo of the PDSCH and the symbol l<NUM>+<NUM> of the PDSCH.

For example, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol l<NUM>+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH.

For another example, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM> and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+<NUM> or a symbol lo+<NUM> of the PDSCH. For another example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH. Alternatively, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol l<NUM>+<NUM> of the PDSCH.

Further, considering that there is a relatively small symbol interval between time domain positions of different DMRSs on the PDSCH, reliability of channel estimation may be affected. In some embodiments, when N is <NUM>, it may be defined in a communications protocol that the time domain position of the first DMRS on the PDSCH is a start symbol lo of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol lo+<NUM> or a symbol lo+<NUM> of the PDSCH, and the time domain position of the third DMRS on the PDSCH is a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH.

For example, a value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM> and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol lo+<NUM> of the PDSCH. For another example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the second DMRS on the PDSCH may be a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the third DMRS on the PDSCH may be a symbol l<NUM>+<NUM> of the PDSCH. A value of Δl<NUM> may be a value of Δl that enables the quantity of candidate PDSCHs that meet the first condition to be greater than or equal to the first threshold and that is in <NUM>, <NUM>, and <NUM> in Table <NUM>. For example, when the first threshold is <NUM> and Δl is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to <NUM>. Therefore, the time domain position of the fourth DMRS on the PDSCH may be a symbol lo+<NUM> or a symbol l<NUM>+<NUM> of the PDSCH.

Further, considering that there is a relatively small symbol interval between time domain positions of different DMRSs on the PDSCH, reliability of channel estimation may be affected. In some embodiments, when N is <NUM>, it may be defined in a communications protocol that the time domain position of the first DMRS on the PDSCH is a start symbol l<NUM> of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol l<NUM>+<NUM> of the PDSCH, the time domain position of the third DMRS on the PDSCH is a symbol lo+<NUM> of the PDSCH, and the time domain position of the fourth DMRS on the PDSCH is a symbol lo+<NUM> of the PDSCH.

For example, the time domain position of the first DMRS on the PDSCH is the start symbol lo of the PDSCH, the time domain position of the second DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, the time domain position of the third DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, and the time domain position of the fourth DMRS on the PDSCH is a symbol l<NUM>+Δl<NUM> of the PDSCH, where Δl<NUM>=<NUM>, Δl<NUM>=<NUM>, and Δl<NUM>=<NUM>. For example, the time domain position of the DMRS set on the PDSCH may be defined in the communications protocol in the following manner:.

The one-symbol DMRS is used as an example. Based on the foregoing descriptions, a time domain position, designed for each of a <NUM> subcarrier spacing and a <NUM> subcarrier spacing, of a DMRS set on a PDSCH may be shown in Table <NUM>.

Alternatively, in some other embodiments, a time domain position of a DMRS set on a PDSCH may be uniformly designed for different subcarrier spacings. When a time domain position of a DMRS set on a PDSCH is designed for different subcarrier spacings, a <NUM> subcarrier spacing and a <NUM> subcarrier spacing are used as an example. A value of Δl is required to enable, at the different subcarrier spacings, a quantity of candidate PDSCHs that meet a first condition to be greater than or equal to a first threshold. Further, in still some other embodiments, a quantity of candidate PDSCHs that meet a second condition at the different subcarrier spacings is less than or equal to a second threshold. For example, a value of the first threshold may be <NUM>, and a value of the second threshold may be <NUM> or <NUM>. In an example, a manner of uniformly designing a time domain position of a DMRS set on a PDSCH for different subcarrier spacings may be represented by using Table <NUM>.

It should be understood that, when the DMRS set corresponds to the <NUM> subcarrier spacing, a <NUM> subcarrier spacing, or a <NUM> subcarrier spacing, a time domain position of a DMRS set on a PDSCH may be predefined with reference to a manner for the <NUM> subcarrier spacing or the <NUM> subcarrier spacing, or may be predefined in a scenario of the <NUM> subcarrier spacing or the <NUM> subcarrier spacing. For example, when the DMRS set corresponds to the <NUM> subcarrier spacing, a time domain position of a DMRS set on a PDSCH may be predefined in the scenario of the <NUM> subcarrier spacing, or may be predefined in the scenario of the <NUM> subcarrier spacing.

In addition, this application may alternatively be applied to a two-symbol DMRS, a three-symbol DMRS, or the like. A manner of defining a time domain position of a DMRS set on a PDSCH is described by using the two-symbol DMRS as an example.

When a value of N is <NUM>, the DMRS set includes a first DMRS and a second DMRS. The first DMRS and the second DMRS are two-symbol DMRSs. Time domain positions of the first DMRS on the PDSCH are a start symbol lo and a symbol l<NUM>+<NUM> of the PDSCH. In this case, time domain positions of the second DMRS on the PDSCH are a symbol l<NUM>+Δl and a symbol l<NUM>+Δl+<NUM> of the PDSCH. Δl may be understood as a quantity of symbols between a start symbol of the first DMRS and a start symbol of the second DMRS. The start symbol of the first DMRS may be understood as the start symbol of the PDSCH, and the start symbol of the second DMRS may be understood as the symbol l<NUM>+Δl of the PDSCH.

As shown in <FIG>, when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set, candidate PDSCHs of the nine-symbol PDSCH are respectively a candidate PDSCH <NUM>, a candidate PDSCH <NUM>, and a candidate PDSCH <NUM>. For example, the candidate PDSCH <NUM> is used as an example. If time domain positions of a first DMRS on the candidate PDSCH <NUM> are a symbol <NUM> and a symbol <NUM> in the slot j, a start symbol of the first DMRS is the symbol <NUM> in the slot j. If time domain positions of a second DMRS on the candidate PDSCH <NUM> are a symbol <NUM> and a symbol <NUM> in the slot j, a start symbol of the second DMRS is the symbol <NUM> in the slot j. It can be learned from <FIG> that, for the nine-symbol PDSCH, when Δl=<NUM>, the quantity of candidate PDSCHs that meet the first condition is <NUM>, and the candidate PDSCHs are respectively the candidate PDSCH <NUM> and the candidate PDSCH <NUM>. When the start symbol of the PDSCH does not overlap the time domain position of the CRS set, the quantity of PDSCHs that meet the second condition is also <NUM>, and the PDSCH is the candidate PDSCH <NUM>.

Similarly, <FIG> are schematic diagrams of a time domain position of a DMRS set on a candidate PDSCH when a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM> to <NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set. <FIG> is a schematic diagram of a time domain position of a DMRS set on a candidate PDSCH when a <NUM>-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set.

A two-symbol DMRS is used as an example. <FIG> are schematic diagrams of a time domain position of a DMRS set on a candidate PDSCH when a frame structure parameter corresponding to the DMRS set is a <NUM> subcarrier spacing, a frame structure parameter corresponding to a CRS set is a <NUM> subcarrier spacing, a time domain position, on a subframe i, of each CRS in the CRS set may be shown in B in <FIG>, a value of N is <NUM>, a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM> to <NUM>, and a start symbol of a PDSCH does not overlap a time domain position of the CRS set. <FIG> is a schematic diagram of a time domain position of a DMRS set on a candidate PDSCH when a <NUM>-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set.

A two-symbol DMRS is used as an example. <FIG> are schematic diagrams of a time domain position of a DMRS set on a candidate PDSCH when a frame structure parameter corresponding to the DMRS set is a <NUM> subcarrier spacing, a frame structure parameter corresponding to a CRS set is a <NUM> subcarrier spacing, a time domain position, on a subframe i, of each CRS in the CRS set may be shown in A in <FIG>, a value of N is <NUM>, a nine-symbol PDSCH is scheduled in a slot j, Δl=<NUM> to <NUM>, and a start symbol of a PDSCH does not overlap a time domain position of the CRS set. <FIG> is a schematic diagram of a time domain position of a DMRS set on a candidate PDSCH when a <NUM>-symbol PDSCH is scheduled in a slot j, Δl=<NUM>, and a start symbol of a PDSCH does not overlap a time domain position of a CRS set.

With reference to <FIG>, <FIG>, <FIG>, and <FIG>, when a value of N is <NUM>, the frame structure parameters corresponding to the DMRS set are the <NUM> subcarrier spacing and the <NUM> subcarrier spacing, the duration L of the PDSCH is <NUM> or <NUM>, and Δl has different values, statistics about the quantity of candidate PDSCHs that meet the first condition are shown in Table <NUM>.

According to Table <NUM>, a value of the first threshold may be set based on an actual situation. For example, the value of the first threshold is <NUM>. For the <NUM> subcarrier spacing, when Δl=<NUM>, the duration L of the PDSCH is nine or <NUM> symbols, and the quantity of antenna ports of the CRS is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to the first threshold. Therefore, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and a symbol l<NUM>+<NUM> of the PDSCH in a communications protocol. For example, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo of the PDSCH and the symbol lo+<NUM> of the PDSCH in the communications protocol in the following manner:.

For example, the value of the first threshold is <NUM>. For the <NUM> subcarrier spacing, when Δl=<NUM> or <NUM>, the duration L of the PDSCH is nine or <NUM> symbols, and the quantity of antenna ports of the CRS is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to the first threshold. Therefore, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo and a symbol l<NUM>+<NUM> of the PDSCH and the symbol lo+<NUM> and a symbol lo+<NUM> of the PDSCH in a communications protocol.

The duration L of the PDSCH is <NUM>, and the value of the first threshold is <NUM>. In this case, for the <NUM> subcarrier spacing, when Δl=<NUM>, and the quantity of antenna ports of the CRS is <NUM> or <NUM>, the quantity of candidate PDSCHs that meet the first condition is greater than or equal to the first threshold. Therefore, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo and a symbol l<NUM>+<NUM> of the PDSCH and a symbol l<NUM>+<NUM> and a symbol lo+<NUM> of the PDSCH in a communications protocol.

In addition, alternatively, a time domain position of a DMRS set on a PDSCH may be unified for different subcarrier spacings. For example, a value of the first threshold is <NUM>. For a <NUM> subcarrier spacing and a <NUM> subcarrier spacing, when Δl=<NUM>, a quantity of candidate PDSCHs that meet a first condition is greater than or equal to the first threshold. Therefore, the time domain position of the DMRS set on the PDSCH may be defined as the start symbol lo and the (l<NUM>+<NUM>)th symbol of the PDSCH and a symbol l<NUM>+<NUM> and a symbol lo+<NUM> of the PDSCH in a communications protocol. In this case, regardless of whether the <NUM> subcarrier spacing or the <NUM> subcarrier spacing is used, when a nine-symbol PDSCH or a <NUM>-symbol PDSCH is scheduled in the slot j, the time domain position of the DMRS set on the PDSCH is the start symbol lo and the symbol l<NUM>+<NUM> of the PDSCH and the symbol lo+<NUM> and the symbol lo+<NUM> of the PDSCH.

For related implementation when a value of N is <NUM> or <NUM>, refer to related descriptions in the one-symbol DMRS.

Based on the foregoing embodiments, as shown in <FIG>, an embodiment of this application further provides a communication method. The communication method specifically includes the following steps.

<NUM>: The network device sends second indication information to the terminal device. The second indication information is used to indicate a scheduled PDSCH.

<NUM>: The terminal device receives the first indication information and the second indication information, and receives, on the scheduled PDSCH based on the first indication information and the second indication information, data sent by the network device.

When N is <NUM>, and the DMRS set includes a first DMRS and a second DMRS, the first indication information is specifically used to indicate:.

When N is <NUM>, the first indication information is specifically used to indicate:.

In <FIG>, the time domain position of the DMRS set on the PDSCH is predefined in a protocol. For a related predefinition manner, refer to the foregoing related descriptions.

The embodiments of this application may be used separately, or may be used in combination, to achieve different technical effects.

In the embodiments provided in this application, the communication method provided in the embodiments of this application is described from a perspective in which the terminal device is used as an execution body. To implement functions in the communication method provided in the embodiments of this application, the terminal device may include a hardware structure and/or a software module, and implement the functions in a form of the hardware structure, the software module, or a combination of the hardware structure and the software module. Whether a function in the foregoing functions is performed by the hardware structure, the software module, or the combination of the hardware structure and the software module depends on particular applications and design constraints of the technical solutions.

Same as the foregoing concept, as shown in <FIG>, an embodiment of this application further provides an apparatus <NUM>. The apparatus <NUM> includes a transceiver module <NUM> and a processing module <NUM>.

In an example, the apparatus <NUM> is configured to implement a function of the terminal device in the foregoing methods. The apparatus <NUM> may be a terminal device or an apparatus in a terminal device. The apparatus may be a chip system. In this embodiment of this application, the chip system may include a chip, or may include a chip and another discrete component.

The processing module <NUM> is configured to receive data from a network device through the transceiver module <NUM> based on first indication information and second indication information. The transceiver module <NUM> is configured to: receive the first indication information from the network device, or receive the second indication information from the network device.

In an example, the apparatus <NUM> is configured to implement a function of the network device in the foregoing methods. The apparatus <NUM> may be a network device or an apparatus in a second terminal device. The apparatus may be a chip system. In this embodiment of this application, the chip system may include a chip, or may include a chip and another discrete component.

The transceiver module <NUM> is configured to: send first indication information to a terminal device, send second indication information to a terminal device, or send data to a terminal device. The processing module <NUM> is configured to: schedule the data to a PDSCH indicated by the second indication information, and send the data to the terminal device through the transceiver module <NUM>.

For a specific execution process of the processing module <NUM> and the transceiver module <NUM>, refer to the descriptions in the foregoing method embodiments. Division into modules in the embodiments of this application is an example, is merely logical function division, and may be other division during actual implementation. In addition, function modules in the embodiments of this application may be integrated into one processor, or each of the modules may exist alone physically, or two or more modules may be integrated into one module. The integrated module may be implemented in a form of hardware, or may be implemented in a form of a software function module.

Same as the foregoing concept, as shown in <FIG>, an embodiment of this application further provides an apparatus <NUM>.

In an example, the apparatus <NUM> is configured to implement a function of the terminal device in the foregoing methods. The apparatus <NUM> may be a terminal device or an apparatus in a terminal device. The apparatus <NUM> includes at least one processor <NUM>, configured to implement a function of the terminal device in the foregoing methods. For example, the processor <NUM> may be configured to receive data from a network device based on first indication information and second indication information. For details, refer to detailed descriptions in the methods.

In some embodiments, the apparatus <NUM> may further include at least one memory <NUM>, configured to store a program instruction and/or data. The coupling in this embodiment of this application may be indirect coupling or a communication connection between apparatuses, units, or modules in an electrical form, a mechanical form, or another form, and is used for information exchange between the apparatuses, the units, or the modules. In another implementation, the memory <NUM> may alternatively be located outside the apparatus <NUM>. The processor <NUM> may operate in collaboration with the memory <NUM>. The processor <NUM> may execute the program instruction stored in the memory <NUM>. At least one of the at least one memory may be included in the processor.

In some embodiments, the apparatus <NUM> may further include a communications interface <NUM>, configured to communicate with another device through a transmission medium, so that an apparatus in the apparatus <NUM> can communicate with the another device. For example, the communications interface <NUM> may be a transceiver, a circuit, a bus, a module, or another type of communications interface, and the another device may be a second terminal device or a network device. The processor <NUM> receives and sends data through the communications interface <NUM>, and is configured to implement the method in the foregoing embodiments. For example, the communications interface <NUM> may be configured to receive the first indication information, the second indication information, the data, or the like sent by the network device.

In an example, the apparatus <NUM> is configured to implement a function of the network device in the foregoing methods. The apparatus <NUM> may be a network device or an apparatus in a network device. The apparatus <NUM> includes at least one processor <NUM>, configured to implement a function of the network device in the foregoing methods. For example, the processor <NUM> may schedule data to a PDSCH indicated by second indication information, and send the data to a terminal device. For details, refer to detailed descriptions in the methods.

In some embodiments, the apparatus <NUM> may further include a communications interface <NUM>, configured to communicate with another device through a transmission medium, so that an apparatus in the apparatus <NUM> can communicate with the another device. For example, the communications interface <NUM> may be a transceiver, a circuit, a bus, a module, or another type of communications interface, and the another device may be a second terminal device or a network device. The processor <NUM> receives and sends data through the communications interface <NUM>, and is configured to implement the method in the foregoing embodiments. For example, the communications interface <NUM> may be configured to send first indication information, second indication information, or data to the terminal device.

In this embodiment of this application, a connection medium between the communications interface <NUM>, the processor <NUM>, and the memory <NUM> is not limited. For example, in this embodiment of this application, in <FIG>, the memory <NUM>, the processor <NUM>, and the communications interface <NUM> may be connected by using a bus. The bus may be classified into an address bus, a data bus, a control bus, and the like.

In this embodiment of this application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or another programmable logic device, a discrete gate or a transistor logic device, or a discrete hardware component, and may implement or perform the methods, the steps, and logical block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor, any conventional processor, or the like. The steps in the methods disclosed with reference to the embodiments of this application may be directly performed and completed through a hardware processor, or may be performed and completed through a combination of hardware in the processor and a software module.

In the embodiments of this application, the memory may be a nonvolatile memory, such as a hard disk drive (hard disk drive, HDD) or a solid-state drive (solid-state drive, SSD), or may be a volatile memory (volatile memory), such as a random access memory (random-access memory, RAM). The memory is any other medium that can be used to carry or store expected program code in a form of an instruction or a data structure and that can be accessed by a computer, but is not limited thereto. The memory in this embodiment of this application may alternatively be a circuit or any other apparatus that can implement a storage function, and is configured to store a program instruction and/or data.

Claim 1:
A communication method, performed by a communication apparatus,
wherein the method comprises:
receiving first indication information from a network device, wherein the first indication information indicates a time domain position of a demodulation reference signal, DMRS, set on a physical downlink shared channel, PDSCH; and the DMRS set comprises N DMRSs, wherein N is a positive integer greater than or equal to <NUM>; and
receiving, on the PDSCH based on the first indication information, data sent by the network device.
the method being characterized in that
when N is <NUM>, the DMRS set comprises a first DMRS and a second DMRS, and a length of the first DMRS and a length of the second DMRS in time domain each are one symbol, the first indication information indicates:
a PDSCH mapping type being a type B; when L is <NUM>, l<NUM> is <NUM> and Δl<NUM> is <NUM> and when L is <NUM>, l<NUM> is <NUM> and Δl<NUM> is <NUM>; or
when N is <NUM>, the DMRS set comprises a first DMRS, a second DMRS, and a third DMRS, and a length of the first DMRS, a length of the second DMRS, and a length of the third DMRS in time domain each are one symbol, the first indication information indicates:
a PDSCH mapping type being a type B; when L is <NUM>, l<NUM> is <NUM>, Δl<NUM> is <NUM> and Δl<NUM> being <NUM> and when L is <NUM>, l<NUM> is <NUM>, Δl<NUM> is <NUM> and Δl<NUM> is <NUM>;
wherein L is used to indicate a total quantity of symbols of the PDSCH; l<NUM> is used to indicate a start symbol of the first DMRS on the PDSCH; Δl<NUM> is used to indicate a quantity of symbols between a start symbol of the PDSCH and a start symbol of the second DMRS on the PDSCH; and Δl<NUM> is used to indicate a quantity of symbols between the start symbol of the PDSCH and a start symbol of the third DMRS on the PDSCH.