Patent Description:
This application relates to the field of communications technologies, and in particular, to a method and an apparatus for transmitting a reference signal, and a method and an apparatus for receiving a reference signal.

In a 3rd Generation Partnership Project (3rd Generation Partnership Project, 3GPP) Long Term Evolution (Long Term Evolution, LTE) or LTE-advanced (LTE-advanced, LTE-A) system, an orthogonal frequency division multiple access (orthogonal frequency division multiple access, OFDMA) mode is generally used as a downlink multiple access mode. Downlink resources of the system are divided into a plurality of orthogonal frequency division multiplexing (orthogonal frequency division multiplexing, OFDM) symbols in terms of a time domain, and are divided into several subcarriers in terms of a frequency domain.

Generally, a normal uplink or downlink subframe includes two timeslots (slot), and each timeslot includes seven OFDM symbols. Therefore, a normal uplink or downlink subframe includes <NUM> OFDM symbols in total. In addition, a size of a physical resource block (physical resource block, PRB) is also defined in the system. An RB includes <NUM> subcarriers in a frequency domain, and has duration of a half subframe (one timeslot) in a time domain, that is, includes seven OFDM symbols (symbol). A timeslot with a length of a normal cyclic prefix (cyclic prefix, CP) includes seven OFDM symbols, and a timeslot with a length of an extended cyclic prefix includes six OFDM symbols. A subcarrier in an OFDM symbol is referred to as a resource element (resource element, RE). Therefore, one RB includes <NUM> or <NUM> REs. In a subframe, a pair of RBs in two timeslots is referred to as a resource block pair (RB pair). During uplink data transmission, among seven OFDM symbols of a timeslot, a fourth OFDM symbol is an uplink demodulation pilot, and other symbols may be used to carry data, as shown in <FIG>.

In a current 3GPP protocol, although four uplink transmit antennas are defined, and four power amplifiers (Power Amplifier, PA) for simultaneously transmitting sounding reference signals (sounding reference signal, SRS) are supported, actually, no terminal with two or more PAs is in commercial use. In comparison with uplink data transmission in LTE, in a new generation transmission protocol, UE supports more uplink transmit antennas, for example, supports six or even eight uplink transmit antennas. However, due to a cost limitation, a quantity of PAs actually supported by the UE is usually less than or equal to a quantity of transmit antennas of the UE.

In addition, different panels (panel) are also supported for uplink transmission of the UE. There is a relatively strong correlation between a plurality of antennas in a same panel, but channel transmission features and blocking probabilities corresponding to antennas in different panels are different.

When the UE has a plurality of antennas, and the antennas are located in different panels, dynamic switching between antenna port groups cannot be implemented according to different transmission requirements in the prior art, and further, channel quality measurement cannot be performed quickly and effectively within an entire system bandwidth. For example, in a time division duplex (time division duplex, TDD) system, UE transmits an SRS to a base station so that uplink or downlink channel quality information is obtained. If the UE has P (P≥<NUM>) transmit antennas but has only Q (Q<P) PAs, because the UE does not support SRS transmission by the P antennas based on alternate switching between Q antenna port groups, the base station cannot quickly and effectively obtain quality information of channels between all transmit antennas of the UE and receive antennas of the base station and channels between all receive antennas of the UE and transmit antennas of the base station. Therefore, there is a relatively great performance loss. <CIT> discloses receiving SRSs transmitted according SRS request, wherein antenna ports that perform uplink transmission are divided into a first group and a second group, the SRSs are transmitted through antenna ports in one of the first and the second group.

This application provides a method and an apparatus for transmitting an uplink reference signal by a second network device, and a method for transmitting an uplink reference signal from a second network device and receiving the uplink reference signal by a first network device, so that UE traverses an entire system bandwidth on all antennas as quickly as possible and that accuracy of uplink reference signal transmission is improved. This present application is defined by independent claims. Additional features of the present application are presented in the dependent claims.

To describe the technical solutions in this application more clearly, the following briefly describes the accompanying drawings required for describing the embodiments. Apparently, a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

The embodiments of this application are applied to a communications system including at least one first network device used as a transmitting device and at least one second network device used as a receiving device. The transmitting device and the receiving device may be any transmit end device and receive end device for performing data transmission in a wireless mode. The transmitting device and the receiving device may be any device having wireless transmitting and receiving functions, including but not limited to a base station (NodeB), an evolved NodeB (eNodeB), a base station in a fifth generation (the fifth generation, <NUM>) communications system, a base station or a network device in a future communications system, an access point in a Wi-Fi system, a wireless relay node, a wireless backhaul node, user equipment (user equipment, UE), and the like.

The UE may also be referred to as a terminal, a mobile station (mobile station, MS), a mobile terminal (mobile terminal, MT), a remote device (remote terminal, RT), an access terminal (access terminal, AT), a user agent (user agent, UA), or the like. The UE may communicate with one or a plurality of core networks through a radio access network (radio access network, RAN), or may access a distributed network in a self-organizing or unauthorized mode. The UE may further communicate with a wireless network in another mode, or the UE may directly perform wireless communication with another UE. This is not limited in this embodiment of this application.

A method for transmitting a reference signal or a sounding reference signal (Sounding Reference Signal, SRS) according to the embodiments of this application may be applicable to downlink data transmission, or may be applicable to uplink data transmission. For downlink data transmission, a transmitting device is a base station, and a corresponding receiving device is UE. For uplink data transmission, a transmitting device is UE, and a corresponding receiving device is a base station. For D2D data transmission, a transmitting device is UE, and a corresponding receiving device is also UE. This is not limited in this embodiment of this application.

An SRS port group switching method provided by the embodiments of this application may be applied to various communications systems, for example, an LTE system, and WCDMA, <NUM>, <NUM>, and <NUM> systems. Application scenarios are not limited in this application.

An embodiment of this application provides a method for adaptive antenna grouping and dynamic antenna switching based on the grouping. Considering that channel transmission features and blocking probabilities corresponding to different panels are different, but different transmission schemes have different reference signal transmission and measurement requirements, for example, a transmission scheme of transmit diversity requires high reliability, a plurality of antennas located in different panels may be grouped into one group if possible during grouping of SRS ports, thereby overcoming interruption of a user's uplink signal transmission caused by random blocking in uplink signal transmission. For a closed-loop transmission mode, higher channel quality measurement precision is required. During grouping of SRS ports, a plurality of antennas located in a same panel may be grouped into one group if possible, so that accurate channel quality measurement can be implemented for the plurality of antennas in the same panel. Especially for tracking some channel quality information that changes quickly, for example, tracking phase rotation information between two polarization directions, a measurement result can be obtained more quickly and accurately only when measurement is performed based on the plurality of antennas located in the same antenna panel.

Specifically, using uplink reference signal transmission as an example, in this embodiment, a first network device and a second network device are included. The first network device is a base station, and the second network device is UE. The method for transmitting a reference signal includes the following steps.

Referring to <FIG> is a schematic flowchart of a method for transmitting a reference signal.

Step <NUM>: A base station transmits first group information of a reference signal port to UE, where the first group information includes information about N groups of a reference signal port, N is a positive integer, and N≥<NUM>. That is, the UE receives the first group information of the reference signal port from the base station.

N represents a quantity of port groups included in the UE. When N is equal to <NUM>, it indicates that the first group information includes information about one group of a reference signal port. When N is greater than <NUM>, it indicates that the first group information includes group information of two or more groups of reference signal ports.

Information of each group of reference signal ports includes at least one of a reference signal port quantity corresponding to the port group and reference signal port numbers, or other information. The reference signal port quantity included in each group of reference signal ports is greater than or equal to <NUM>, and reference signal port quantities included in different port groups may be the same or different. For example, all reference signal ports of the UE are grouped into three groups: a first group, a second group, and a third group. Each group includes at least one antenna port. For example, the first group includes two reference signal port numbers, and the second group and the third group include three port numbers respectively. In the reference signal port group information configured by the base station at this time, port quantities in the second group and the third group are the same. Optionally, during group next time, all port numbers included in any two groups may be different. This is not limited herein.

That the UE receives the first group information of the reference signal port from the base station specifically includes: the UE receives signaling from the base station, where the signaling indicates the first group information of the reference signal port. Further, the signaling includes at least one of higher layer signaling, layer <NUM> signaling, and layer <NUM> signaling. The higher layer signaling may be radio resource control (Radio Resource Control, RRC) signaling or radio link control (Radio Link Control, RLC) signaling. The layer <NUM> signaling may be physical layer signaling (such as downlink control information DCI). The layer <NUM> signaling may be MAC CE signaling, or the like. Specifically, which of the foregoing signaling is used by the base station to transmit the reference signal group information may be determined according to a requirement and an application scenario, and is not limited in this embodiment.

Step <NUM>: The UE determines a kth group of a reference signal antenna port in the N groups of reference signal ports, where k is a positive integer, and N≥k≥<NUM>.

Step <NUM>: The UE transmits a reference signal on the kth group of reference signal antenna port.

When N is equal to <NUM>, the UE determines the first group of reference signal antenna port, and transmits the reference signal to the base station by using the first group of reference signal antenna port. In this case, k is equal to N, and the UE transmits the reference signal by using the group of reference signal ports configured by the base station. When N is greater than <NUM>, the UE selects, from the information of the N groups of reference signal ports, the antenna port group number k for transmitting the reference signal, and N≥k><NUM>; and the UE transmits the reference signal to the base station by using the kth group of antenna ports.

Correspondingly, the base station receives the reference signal from the UE, and the reference signal is a reference signal corresponding to the kth group of reference signal ports in the N groups of reference signal ports. The corresponding reference signal is the reference signal transmitted by the UE by using the kth group of reference signal antenna port.

In addition, if the kth group of antenna ports determined by the UE is different from a port on which the UE currently transmits the reference signal, at a time n, the UE first determines and switches to the kth group of reference signal antenna port, and then transmits the reference signal.

Optionally, that the UE determines a kth group of reference signal antenna port in the N groups of reference signal port according to the information of the N groups of reference signal ports in step <NUM> includes: the UE determines the kth group of reference signal antenna port according to at least one of the time n for transmitting the reference signal, the group quantity N of the reference signal port, and a quantity K of times that the reference signal is transmitted.

Specifically, that the UE determines the kth group of reference signal antenna port according to the occasion for transmitting the reference signal, the group quantity N of the reference signal port, and a quantity K of times that the reference signal is transmitted includes:.

According to different scenarios and requirements, a function of selecting or switching an antenna port for transmitting an uplink signal by the UE may be adaptively configured to two states: "enabled" or "disabled".

When the function of selecting an antenna port of the UE is in the enabled state, a user may select an antenna port for transmitting an uplink signal, and a port number for transmitting a reference signal at a time may be determined according to whether reference signal transmission in a frequency hopping (hopping) is allowed.

Specifically, according to the following relation: <MAT> the reference signal corresponding to the determined kth group of reference signal ports may be received,
where <MAT> n represents the occasion for transmitting the reference signal, k(n) represents the antenna port group number k determined for the reference signal at the time n, K represents the quantity of times that the reference signal is transmitted, K≥<NUM>, and mod represents a modulo operation.

The following provides two manners of determining the antenna port group number k for the UE to transmit the reference signal at the time n.

A manner of determining the antenna port group number k for transmitting the uplink signal at the time n includes: when the UE is in a frequency hopping state, and N is equal to <NUM>, that is, the UE transmits the reference signal by using two groups of ports, according to the following first relation: <MAT> the antenna port group number k for the reference signal is determined,
where <MAT> n represents the occasion for transmitting the reference signal, k(n) represents the antenna port group number k determined for the reference signal at the time n, and K represents the quantity of times that the reference signal is transmitted. Specifically, herein K represents the quantity of times that the reference signal is transmitted and which is required for the UE to traverse an entire to-be measured bandwidth in a channel measurement process. K is a positive integer greater than or equal to <NUM>.

Optionally, the occasion for transmitting the reference signal may be any one of a subframe, a timeslot, a minimum timeslot, and an OFDM symbol, that is, the time n may be a subframe n, or a timeslot n, or a minimum timeslot n, or an OFDM symbol n. In addition, the time may be any time unit other than those defined above. This is not limited herein.

For example, if n represents a subframe, k(n) may represent a corresponding transmit antenna port number when a reference signal is transmitted in the subframe n. The UE transmits the reference signal for K times by using different reference signal transmit antenna ports in a channel measurement process, and can further traverse the entire to-be-measured bandwidth. This further improves precision of channel quality measurement.

Another manner of determining k includes: likewise, when the function of selecting an antenna port of the UE is in the enabled state, a user selects an antenna port group. An index of an antenna port group for transmitting a reference signal at a time n may be represented by k(n). In addition, assuming that a frequency hopping state of the UE is enabled, if all reference signal transmit antenna ports of the UE are grouped into four groups (N=<NUM>), when a reference signal is transmitted by using the four groups of antenna ports, according to the following second relation: <MAT> the antenna port group number k for the reference signal may be determined,
where <MAT> n represents the occasion for transmitting the reference signal, k(n) represents the antenna port group number k determined for the reference signal at the time n, and K represents the quantity of times that the reference signal is transmitted. Specifically, herein K represents the quantity of times that the reference signal is transmitted and which is required for the UE to traverse an entire to-be measured bandwidth in a channel measurement process. K is a positive integer greater than or equal to <NUM>.

It should be noted that, in this application, other relations or predefined manners may also be used to determine the antenna port group number k for the UE to transmit the reference signal at the time n. This is not limited in this embodiment.

Optionally, in the foregoing step <NUM>, before the UE receives the first group information of reference signal that is transmitted by the base station, the method further includes: the UE reports second group information to the base station, so that the base station can determine the first group information according to the second group information. The second group information includes at least one of antenna panel information, reference signal port information, and reference signal port group information of the UE.

The antenna panel information includes at least one of a distribution structure of all antennas of the UE and a panel pattern (panel pattern), or other information. Herein the panel pattern information further includes at least one of a quantity of panels and a distribution pattern of P (P≥<NUM>) panels, or other information. The distribution pattern information of the panels may be a plurality of panel distribution patterns predefined on the base station and the user side. For example, <FIG> is a schematic structural diagram of four antenna panel patterns, where × represents a pair of reference signal antenna ports in two polarization directions, different reference signal antenna ports are distributed in different positions of the terminal device, and different antenna port panel patterns are generated.

The reference signal port information includes the quantity of reference signal ports of the UE, a port number of each reference signal port, and other information. The reference signal port group information includes group information that is generated after group of all reference signal antenna ports and is recommended by the UE. For example, all antenna ports are grouped, according to odd and even numbers in numbering, into two groups to generate group information. Alternatively, all antenna ports are grouped into P groups according to P antenna panels, where antenna ports located in a panel belong to a group.

Optionally, the reference signal port group information in the second group information may be the same as or different from the first group information of the reference signal ports that is transmitted by the base station in step <NUM>. After the base station receives the second group information of the UE, the base station may determine, according to an uplink transmission scheme configured by the base station for the UE, whether to use antenna port group information same as the second group information.

In addition, the second group information reported by the UE to the base station may further include transmission scheme information of the UE or a channel quality result previously obtained by the UE through measurement, where the channel quality result includes uplink channel quality measurement information such as a CQI. The base station performs reception the group information of reference signal port according to different transmission schemes required by the UE, for example, uplink transmit diversity, an open-loop transmission mode, and a closed-loop transmission mode, and determines, according to the transmission scheme, the reference signal port group information to be delivered to the UE.

In the method provided by this embodiment, the user equipment UE determines, in the N groups of reference signal ports according to the received group information of reference signal ports from the base station, the kth group of antenna ports for transmitting the reference signal, and then transmits the reference signal by using the kth group of antenna ports. In this way, quick switching between the reference signal antenna ports of the UE is implemented, and the reference signal is transmitted by using a port after the switching. For the reference signal port after the switching, channel transmission features and blocking probabilities corresponding to different antenna panel structures and a transmission requirement of a current transmission scheme are considered. Therefore, effective adaptive uplink data transmission can be performed, the transmitted reference signal can traverse the entire to-be-measured bandwidth as quickly as possible, and accuracy of channel measurement and efficiency of uplink data transmission are improved.

In a specific embodiment, the base station receives the second group information reported by the UE, and the second group information includes a quantity of ports and port numbers used when the UE transmits an uplink signal. For example, the UE has eight antenna ports in total, and the eight antenna ports are numbered from <NUM> to <NUM> respectively. After receiving the second group information reported by the UE, the base station groups the eight ports according to the quantity of ports and port numbers of the UE and the current transmission scheme, generates the first group information, and delivers the first group information to the UE. The UE receives the first group information, and determines, according to an indication of the first group information, the antenna port group number k for transmitting the reference signal.

As shown in <FIG>, an indication of the first group information includes: in the first group information, port numbers <NUM>, <NUM>, <NUM>, and <NUM> are grouped into one group, and port numbers <NUM>, <NUM>, <NUM>, and <NUM> are grouped into one group. After receiving the port group information, the UE determines, according to the indication of the port group information, the antenna port group number k for transmitting the reference signal at the time n. Further, according to the indication of the reference signal port group information, the UE determines the port group number k used every time the reference signal is transmitted, where each port group includes at least one antenna port. For example, in a channel measurement process, a reference signal is transmitted for four times, and the following four reference signal port groups are used for transmission at the four times respectively, where port numbers corresponding to each reference signal port group are: {<NUM>, <NUM>, <NUM>, <NUM>}, {<NUM>, <NUM>, <NUM>, <NUM>}, {<NUM>, <NUM>, <NUM>, <NUM>}, and {<NUM>, <NUM>, <NUM>, <NUM>}.

As shown in <FIG> is an implementation of another indication of the first group information. The implementation specifically includes: the UE transmits the reference signal for six times according to the received reference signal port group information, and the reference signal is transmitted every time on a port group including two ports. Further, the UE determines that port numbers used when the reference signal is transmitted every time in the six times are {<NUM>, <NUM>}, {<NUM>, <NUM>}, {<NUM>, <NUM>}, {<NUM>, <NUM>}, {<NUM>, <NUM>}, and {<NUM>, <NUM>} respectively, and then the UE performs switching according to the grouped antenna port numbers and transmits the reference signal sequentially.

The antenna port group information delivered by the base station to the UE may be transmitted by using signaling. Further, the signaling includes higher layer signaling, for example, RRC signaling or RLC signaling, or physical layer signaling, for example, DCI or a MAC CE.

Further, in the foregoing embodiment, the quantity K of times that the reference signal is transmitted on a UE side is the quantity of times that the reference signal is transmitted and which is required for the UE to traverse the entire to-be measured bandwidth in a channel measurement process. Assuming that a frequency hopping function is enabled for the reference signal, but the quantity of times that the reference signal is transmitted and which is required for the UE to measure and traverse the entire to-be measured bandwidth may be determined according to a cell-specific and/or user-specific reference signal bandwidth configuration parameter for the user. Specifically, for a reference signal bandwidth configuration parameter, refer to the following Table <NUM> to Table <NUM>. For example, the reference signal may be a sounding reference signal SRS, or the like.

The foregoing Table <NUM> to Table <NUM> show values of mSRS,b and Nb in cases of different uplink bandwidths and different SRS bandwidth configurations, where mSRS,b represents a frequency domain bandwidth when the SRS is transmitted at a time. Every time a bandwidth for transmitting the SRS by the UE is less than the to-be-measured bandwidth, SRS frequency hopping (hopping) needs to be performed. Generally, it is specified that SRS frequency hopping may be configured by using a higher layer parameter SRS frequency hopping bandwidth (SRS hopping bandwidth), and a range of parameter values are generally bhop ∈ {<NUM>, <NUM>, <NUM>, <NUM>}. When bhop < BSRS, the UE needs to perform SRS frequency hopping, that is, perform frequency hopping only when an SRS transmission bandwidth of the UE is less than a frequency hopping bandwidth. This means that a tree structure node indicated by a UE-specific (specific) SRS bandwidth has a parent node whose bandwidth is a frequency hopping bandwidth in a tree, and the UE performs SRS frequency hopping only when the parent node includes a plurality of child nodes.

For example, referring to <FIG>, in Table <NUM>, assuming CSRS = <NUM> and bhop = <NUM>, the bandwidth that needs to be measured is <NUM> PRBs; if BSRS = <NUM>, the bandwidth for transmitting the SRS every time is four PRBs, and nine times of transmission are required for traversing the entire to-be-measured bandwidth. In Table <NUM> to Table <NUM>, Nb represents a quantity of level-<NUM> nodes. Using CSRS = <NUM> in Table <NUM> as an example, N<NUM> = <NUM> indicates that one node exists on this level, and N<NUM> = <NUM> indicates that three nodes exist on this level. N<NUM> and N<NUM> may be deduced in the same way. <FIG> shows a diagram of a tree structure when N<NUM> = <NUM>, N<NUM> = <NUM>, and N<NUM> = <NUM>. When bhop = <NUM> and BSRS = <NUM>, nine times of SRS transmission are required for traversing a to-be-measured bandwidth corresponding to bhop = <NUM>.

In the method based on antenna port group and provided by this embodiment, the first network device base station can configure corresponding reference signal port group information according to a transmission requirement of the second network device UE. Therefore, according to an indication of the port group information, the second network device UE can switch between the ports for transmitting the uplink reference signal, flexible adaptive group of uplink reference signal antenna ports of the UE and corresponding data transmission are implemented, all antennas of the UE can quickly traverse the entire bandwidth, and accuracy and precision of channel measurement are improved.

Another embodiment of this application further provides an apparatus for transmitting a reference signal. The apparatus is configured to implement the method for transmitting a reference signal in the foregoing embodiment. The apparatus is disposed in a second network device, and the second network device includes a terminal device. As shown in <FIG>, the apparatus for transmitting a reference signal includes a receiving unit <NUM>, a processing unit <NUM>, and a transmission unit <NUM>. In addition, the apparatus may further include other functional units or modules such as a storage unit.

The receiving unit <NUM> is configured to receive first group information of reference signal ports from a first network device, where the first group information includes information about N groups of reference signal ports, N is a positive integer, and N≥<NUM>.

The processing unit <NUM> is configured to determine a kth group of reference signal antenna port in the N groups of reference signal ports, where k is a positive integer, and N≥k≥<NUM>.

The transmission unit <NUM> is configured to transmit a reference signal on the kth group of reference signal antenna port.

Optionally, the processing unit <NUM> is specifically configured to determine the kth group of reference signal antenna port according to at least one of an occasion for transmitting the reference signal, the group quantity N of the reference signal port, and a quantity K of times that the reference signal is transmitted.

Optionally, the processing unit <NUM> is further configured to: according to the following relation: <MAT> determine the antenna port group number k for the reference signal,
where <MAT> n represents the occasion for transmitting the reference signal, k(n) represents the antenna port group number k determined for the reference signal at the time n, K represents the quantity of times that the reference signal is transmitted, and K≥<NUM>;
when N=<NUM>, according to the following first relation: <MAT> determine the antenna port group number k for the reference signal; or
optionally, when N=<NUM>, according to the following second relation: <MAT> determine the antenna port group number k for the reference signal.

Optionally, the transmission unit <NUM> is further configured to report second group information to the first network device, where the second group information includes at least one of antenna panel information, reference signal port information, and reference signal port group information of the second network device.

Optionally, the receiving unit <NUM> is further configured to receive signaling from the first network device, where the signaling indicates the first group information of the reference signal ports; and the signaling includes at least one of higher layer signaling, layer <NUM> signaling, and layer <NUM> signaling.

In addition, this embodiment further provides an apparatus for receiving a reference signal. The apparatus is configured to implement the method for receiving a reference signal in the foregoing embodiment. The apparatus is disposed in a first network device, for example, a base station. As shown in <FIG>, the apparatus for receiving a reference signal includes a receiving unit <NUM>, a processing unit <NUM>, and a transmission unit <NUM>. In addition, the apparatus may further include other functional units or modules such as a storage unit.

The transmission unit <NUM> is configured to transmit first group information of reference signal ports to a second network device, where the first group information includes information about N groups of reference signal ports, N is a positive integer, and N≥<NUM>.

The receiving unit <NUM> is configured to receive a reference signal from the second network device, where the reference signal is a reference signal corresponding to a kth group of reference signal ports in the N groups of reference signal ports, k is a positive integer, and N≥k≥<NUM>.

Optionally, the receiving unit <NUM> is further configured to receive the reference signal corresponding to the kth group of reference signal ports, where the kth group of reference signal ports is determined by the second network device according to at least one of an occasion for transmitting the reference signal, the group quantity N of the reference signal port, and a quantity K of times that the reference signal is transmitted.

Optionally, the receiving unit <NUM> is further configured to: according to the following relation: <MAT> receive the reference signal corresponding to the determined kth group of reference signal ports,
where <MAT> n represents the occasion for transmitting the reference signal, k(n) represents the antenna port group number k determined for the reference signal at the time n, K represents the quantity of times that the reference signal is transmitted, and K≥<NUM>.

Optionally, the receiving unit <NUM> is further configured to receive second group information from the second network device, where the second group information includes at least one of antenna panel information, reference signal port information, and reference signal port group information of the second network device.

The processing unit <NUM> is configured to determine the first group information of the reference signal ports according to the second group information.

Optionally, the transmission unit <NUM> is further configured to transmit the first group information to the second network device by using signaling, where the signaling includes at least one of higher layer signaling, layer <NUM> signaling, and layer <NUM> signaling.

In this embodiment, the second network device determines, in the N groups of reference signal ports according to the received group information of reference signal ports from the first network device, the kth group of antenna ports for transmitting the reference signal, and then transmits the reference signal by using the kth group of antenna ports. In this way, quick switching between the reference signal antenna ports of the second network device is implemented, and the reference signal is transmitted by using a port after the switching. For the reference signal port after the switching, channel transmission features and blocking probabilities corresponding to different antenna panel structures and a transmission requirement of a current transmission scheme are considered. Therefore, effective adaptive uplink data transmission can be performed, the transmitted reference signal can traverse an entire to-be-measured bandwidth as quickly as possible, and accuracy of channel measurement and efficiency of uplink data transmission are improved.

Still another embodiment of this application provides a method for transmitting a reference signal, to reduce indication information signaling overheads. Specifically, when UE has a plurality of different antenna panel structures, different antenna ports are located in different positions of antenna panels. Therefore, given a same quantity of reference signal antenna ports and same port numbers, because the reference signal antenna ports may be located in different panel patterns (panel pattern), the reference signal antenna ports may correspond to different codebook configurations.

As shown in <FIG>, a distance between a port number <NUM> and a port number <NUM> in an antenna port panel pattern <NUM> (pattern <NUM>) on a UE side is a large antenna distance (codebook configuration applicable to a large antenna distance), but a distance between a port number <NUM> and a port number <NUM> in a panel pattern <NUM> (pattern <NUM>) is a small antenna distance (codebook configuration applicable to a small antenna distance). Therefore, codebook configurations corresponding to the antenna port panel pattern <NUM> and panel pattern <NUM> are different. The method provided by this embodiment is used to configure an optimal codebook for antenna ports in each panel pattern, for transmitting an uplink signal, so that uplink data transmission performance can be improved.

To optimize codebook configurations for the panel patterns on the UE side, specifically, a large precoding matrix set, that is, a codebook, is predefined on a base station and the UE side. Given a same quantity of antenna ports of the UE, the precoding matrix set or the codebook includes codewords in all different panel patterns. The base station selects an appropriate codebook subset or precoding matrix subset from the predefined large codebook or precoding matrix set according to coherent information of transmit antenna ports of the UE, and transmits a precoding matrix index corresponding to the codebook subset to the UE, so that the UE determines a weighting factor on the transmit antenna port according to the precoding matrix index, and transmits corresponding data. Therefore, the following is avoided: Because some antenna ports of the UE are blocked, the base station cannot receive corresponding signals that are transmitted, or signal transmission performance is relatively poor.

Further, as shown in <FIG>, the method provided by this embodiment includes the following steps:.

Optionally, the UE receives signaling transmitted by the base station, where the signaling carries the precoding matrix index, and the signaling includes at least one of higher layer signaling (for example, RRC signaling or RLC signaling), layer <NUM> signaling (for example, physical layer signaling, or DCI), or layer <NUM> signaling (for example, MAC CE signaling). An implementation is: the base station transmits the precoding matrix index to the UE by using DCI indication signaling.

Step <NUM>: The UE transmits the data according to the precoding matrix index. For example, an uplink service data channel, or an uplink control channel, or an uplink reference signal such as an SRS, is transmitted.

A process in which the UE determines the precoding matrix according to the precoding matrix index transmitted by the base station specifically includes:
the UE receives information of the first precoding matrix set from the base station, where the information of the first precoding matrix set indicates a subset of the second precoding matrix set; and then the UE determines a codeword index according to the subset of the second precoding matrix set. Optionally, the base station may determine the information of the first precoding matrix set according to a result of measurement previously performed between the base station and the UE.

Specifically, as shown in the following Table <NUM>, the second precoding matrix set includes a codebook or a precoding matrix set composed of precoding matrices corresponding to a total of <NUM> indexes from a precoding matrix index <NUM> to a precoding matrix index <NUM>. Assuming that the precoding matrix set may be divided into three subsets (that is, there are three candidate first precoding matrix sets) corresponding to three index sets, and assuming that the corresponding index sets are <NUM> to <NUM>, <NUM> to <NUM>, and <NUM> to <NUM> respectively, an index in each index set corresponds to a precoding matrix. For example, a precoding matrix corresponding to the precoding matrix index "<NUM>" is <MAT>, assuming that the first index set includes precoding matrix indexes <NUM> to <NUM>.

However, the precoding matrix set including the foregoing <NUM> precoding matrices is predefined on both the UE and the base station. Therefore, the information of the first precoding matrix set transmitted by the base station to the UE needs to include only a set number of a candidate index set, and is delivered to the UE by using the DCI indication signaling. Therefore, DCI indication signaling overheads are reduced.

Optionally, the UE receives, by using signaling, the information of the first precoding matrix set configured by the base station, where the signaling includes at least one of higher layer signaling (for example, RRC signaling or RLC signaling), layer <NUM> signaling (for example, physical layer signaling), or layer <NUM> signaling (for example, MAC CE signaling). An implementation is: the base station transmits the information of the first precoding matrix set to the UE by using the RRC signaling or the RLC signaling.

Another optional implementation is: before step <NUM>, the UE reports the information of the first precoding matrix set to the base station, and the information of the first precoding matrix set is used to recommend, to the base station, which subset of the second precoding matrix set should be selected. The second precoding matrix is a whole set of all precoding matrices of the UE in an antenna port quantity configuration. For example, the second precoding matrix set is a set including precoding matrices under all antenna panel structures, or a set including precoding matrices under all antenna distances.

After receiving the information of the first precoding matrix set, the base station determines the precoding matrix index, and delivers the precoding matrix index to the UE, so that the UE can transmit uplink data by using an optimal precoding matrix according to the precoding matrix index. In addition, because the precoding matrix index is an index of a precoding matrix renumbered and limited in the first precoding matrix set, the base station is prevented from transmitting, to the UE by using DCI, the precoding matrix index corresponding to the second precoding matrix set. In other words, in comparison with a method for indicating an index corresponding to the second precoding matrix set, DCI indication signaling can be reduced.

In this embodiment, the base station transmits the configured precoding matrix index to the UE, so that the UE can determine, according to the precoding matrix index, the precoding matrix used when the UE transmits the data. Because the matrix index is selected from the first precoding matrix set, and the first precoding matrix set is a proper subset of the second precoding matrix set, the precoding matrix index used by the UE can be indicated quickly. In addition, because the precoding matrix index is an index of a precoding matrix renumbered and limited in the first precoding matrix set, in comparison with the method for indicating an index corresponding to the second precoding matrix set, DCI indication signaling is reduced.

In addition, the UE reports the information of the first precoding matrix set to the base station, so that the base station can select an appropriate precoding matrix index for the UE according to the precoding matrix set recommended by the UE. Therefore, the precoding matrix corresponding to the precoding matrix index can adapt to a plurality of possible antenna panel structures on the UE side, optimal precoding matrix configurations in different antenna panel patterns are implemented, and performance of data transmission is improved.

In a specific embodiment, when the base station configures the precoding matrix index, M (M><NUM>) precoding matrix sets are predefined in a system, where each precoding matrix set corresponds to an antenna port panel pattern, and a codeword indicated by each precoding matrix index corresponds to a precoding matrix in a precoding matrix set. That is, each precoding matrix index is an index of a precoding matrix renumbered in a precoding matrix set.

As shown in <FIG>, a codeword structure in the M precoding matrix sets predefined in the system is relevant to distribution of a plurality of antenna ports of the UE and antenna distances between the plurality of antenna ports. Antenna distances between four antenna ports in a same polarization direction in a panel pattern <NUM> (pattern <NUM>) and a panel pattern <NUM> (pattern <NUM>) are relatively large. Therefore, when the base station configures a precoding matrix set, the base station sets codewords in precoding matrix sets corresponding to the panel pattern <NUM> (pattern <NUM>) and the panel pattern <NUM> (pattern <NUM>) as some codewords applicable to large antenna distances. Optionally, the codewords applicable to large antenna distances may be codewords applicable to large antenna distances in a dual-codebook configuration of four antenna ports in an LTE-A system.

As shown in <FIG>, codewords in precoding matrix sets corresponding to a panel pattern <NUM> (pattern <NUM>) and a panel pattern <NUM> (pattern <NUM>) are some codewords applicable to small antenna distances. For example, optionally, the codewords applicable to small antenna distances may be codewords applicable to small antenna distances in a dual-codebook configuration of four antenna ports in an LTE-A system. Further, because the antenna distances between the four antenna ports in the same polarization direction in the panel pattern <NUM> (pattern <NUM>) and the panel pattern <NUM> (pattern <NUM>) are different, different precoding matrix sets may be configured for the panel pattern <NUM> and the panel pattern <NUM> respectively. This is not specifically limited herein in this embodiment.

In addition, different panel patterns on the UE side correspond to different antenna port structures, but port blocking probabilities corresponding to different antenna port structures are different. Therefore, to avoid quality deterioration of a signal received by the base station from the UE due to blocking of a transmit antenna port of the UE, when configuring a precoding matrix set, the base station configures different precoding matrix sets for different antenna panel structures.

Optionally, a precoding matrix in the precoding matrix set may be formed by a column selection vector and phase rotation. For example, referring to the following Table <NUM>, Table <NUM> shows a set of precoding matrices of four uplink antennas whose rank is <NUM>, where indexes of codewords formed by column selection vectors and phase rotation in the foregoing precoding matrix set include indexes <NUM> to <NUM> in Table <NUM>. According to different antenna panel structures on the UE side, different non-zero elements exist in composition of the precoding matrix configured by the base station.

It is assumed that four antenna ports for transmitting uplink data are {<NUM>, <NUM>, <NUM>, <NUM>}.

Precoding matrices whose indexes are <NUM> to <NUM> are precoding matrices determined by the base station and used in an antenna blocking scenario. That is, in this scenario, the precoding matrix set configured by the base station for the UE is a precoding matrix set corresponding to indexes <NUM> to <NUM> in the foregoing table. The precoding matrix indexes configured by the base station and received by the UE are <NUM> to <NUM>. The UE determines, according to the precoding matrix index, the precoding matrix used when data is transmitted. For example, the UE includes two groups of antenna ports for transmitting a reference signal. One group of antenna ports is blocked, and consequently, quality of a signal received by the base station from the group of antenna ports deteriorates.

Corresponding to the method for transmitting a signal according to this embodiment of this application, this embodiment further provides an apparatus for transmitting a signal. The apparatus is disposed in a terminal device. As shown in <FIG>, specifically, the apparatus includes a receiving unit <NUM>, a processing unit <NUM>, and a transmission unit <NUM>.

The receiving unit <NUM> is configured to receive a precoding matrix index determined by a base station in a first index set, where the precoding matrix index is used to determine a precoding matrix used when data is transmitted, each index in the first index set corresponds to a precoding matrix in a first precoding matrix set, the first precoding matrix set is a proper subset of a second precoding matrix set, and any precoding matrix index value in the first index set is less than or equal to a quantity of precoding matrices included in the first precoding matrix set.

The transmission unit <NUM> is configured to transmit the data according to the precoding matrix index. For example, an uplink service data channel, or an uplink control channel, or an uplink reference signal such as an SRS, is transmitted.

Optionally, the receiving unit <NUM> is further configured to receive information of the first precoding matrix set from the base station, where the information of the first precoding matrix set indicates a subset of the second precoding matrix set.

Optionally, the transmission unit <NUM> is further configured to transmit information of the first precoding matrix set to the base station, where the information of the first precoding matrix set indicates a subset of the second precoding matrix set.

Optionally, the receiving unit <NUM> is specifically configured to receive signaling transmitted by the base station, where the signaling carries at least one of the information of the first precoding matrix set and the precoding matrix index, and the signaling includes at least one of higher layer signaling, layer <NUM> signaling, and layer <NUM> signaling.

The information of the first precoding matrix set is transmitted by using RRC signaling or RLC signaling, and the precoding matrix index is transmitted by using DCI indication signaling.

Corresponding to the foregoing apparatus for transmitting a signal, this embodiment further provides an apparatus for receiving a signal. As shown in <FIG>, the apparatus is disposed in a base station. Further, the apparatus includes a receiving unit <NUM>, a processing unit <NUM>, and a transmission unit <NUM>.

The processing unit <NUM> is configured to determine a precoding matrix index in a first index set, where the precoding matrix index is used to determine a precoding matrix used when a terminal device transmits data, each index in the first index set corresponds to a precoding matrix in a first precoding matrix set, the first precoding matrix set is a proper subset of a second precoding matrix set, and any index value in the first index set is less than or equal to a quantity of precoding matrices included in the first precoding matrix set.

The transmission unit <NUM> is configured to transmit the precoding matrix index to the terminal device.

The receiving unit <NUM> is configured to receive the data transmitted by the terminal device according to the precoding matrix index.

Optionally, the processing unit <NUM> is further configured to configure information of the first precoding matrix set, where the information of the first precoding matrix set indicates a subset of the second precoding matrix set.

The transmission unit <NUM> is further configured to transmit the information of the first precoding matrix set to the terminal device.

Optionally, the receiving unit <NUM> is further configured to receive information of the first precoding matrix set transmitted by the terminal device.

The processing unit <NUM> is further configured to determine a subset of the second precoding matrix set according to the information of the first precoding matrix set, and determine the precoding matrix index according to the subset of the second precoding matrix set.

Optionally, the transmission unit <NUM> is specifically configured to transmit signaling, where the signaling carries the information of the first precoding matrix set, and the signaling includes at least one of higher layer signaling, layer <NUM> signaling, or layer <NUM> signaling. The transmission unit <NUM> transmits the information of the first precoding matrix set to the terminal device by using RRC signaling or RLC signaling.

Optionally, the transmission unit <NUM> is specifically configured to transmit signaling to the terminal device, where the signaling carries the precoding matrix index, and the signaling includes at least one of higher layer signaling, layer <NUM> signaling, or layer <NUM> signaling. The transmission unit <NUM> transmits the precoding matrix index to the terminal device by using DCI signaling.

In a specific hardware implementation, this application further provides a terminal device, for example, UE, configured to implement the steps in the foregoing method embodiment.

Referring to <FIG>, the terminal device may include a transceiver <NUM>, a processor <NUM>, a memory <NUM>, and the like.

Specifically, the processor <NUM> is a control center of the terminal device. The processor <NUM> uses various interfaces and lines to connect each part of the whole network device, and performs various functions and/or data processing of the network-side device by running or executing a software program and/or module stored in the memory and invoking data stored in the memory.

The processor <NUM> may be a central processing unit (central processing unit, CPU), a network processor (network processor, NP), or a combination of a CPU and an NP. The processor may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (application-specific integrated circuit, ASIC), a programmable logic device (programmable logic device, PLD), or a combination thereof. The PLD may be a complex programmable logic device (complex programmable logic device, CPLD), a field-programmable gate array (field-programmable gate array, FPGA), generic array logic (generic array logic, GAL), or any combination thereof.

The memory <NUM> may include a volatile memory (volatile memory), for example, a random access memory (random access memory, RAM); and may further include a non-volatile memory (non-volatile memory), for example, a flash memory (flash memory), a hard disk drive (hard disk drive, HDD), or a solid-state drive (solid-state drive, SSD). The memory may further include a combination of the foregoing types of memories.

The transceiver <NUM> may be configured to receive or transmit data. Under control of the processor, the transceiver may transmit data to each node or other devices in a video network system. Under control of the processor, the transceiver may receive data transmitted by each node or other devices.

In this embodiment of this application, the transceiver <NUM> may be configured to receive reference signal port group information transmitted by the first network device, transmit a reference signal to the first network device, and the like in the foregoing embodiment. In <FIG> of the foregoing apparatus embodiment, functions to be implemented by the receiving unit <NUM> may be implemented by the transceiver <NUM> of the terminal device, or implemented by the transceiver <NUM> controlled by the processor <NUM>. Functions to be implemented by the processing unit <NUM> in <FIG> may also be implemented by the processor <NUM> of the terminal device.

As shown in <FIG>, this embodiment further provides a schematic structural diagram of a network device, configured to implement the method for transmitting a reference signal in the foregoing embodiment. The network device may be the first network device in any one of the foregoing embodiments, for example, a base station.

The base station may include a transceiver <NUM>, a processor <NUM>, a memory <NUM>, and the like.

The processor <NUM> is a control center of the network device (base station). The processor <NUM> uses various interfaces and lines to connect each part of the whole network-side device, and performs various functions and/or data processing of the network-side device by running or executing a software program and/or module stored in the memory and invoking data stored in the memory. The processor may be a central processing unit (central processing unit, CPU), a network processor (network processor, NP), or a combination of a CPU and an NP. The processor may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (application-specific integrated circuit, ASIC), a programmable logic device (programmable logic device, PLD), or a combination thereof. The PLD may be a complex programmable logic device (complex programmable logic device, CPLD), a field-programmable gate array (field-programmable gate array, FPGA), generic array logic (generic array logic, GAL), or any combination thereof.

The memory <NUM> may include a volatile memory (volatile memory), for example, a random access memory (random access memory, RAM); and may further include a non-volatile memory (non-volatile memory), for example, a flash memory (flash memory), a hard disk drive (hard disk drive, HDD), or a solid-state drive (solid-state drive, SSD). The memory may further include a combination of the foregoing types of memories. The memory may store a program or code. The processor in the network element may implement functions of the network element by executing the program or code.

The transceiver <NUM> may be configured to receive or transmit data. Under control of the processor, the transceiver may transmit data to a terminal device or other network-side devices. Under control of the processor, the transceiver receives data transmitted by the terminal device or other network-side devices.

In this embodiment of this application, the transceiver <NUM> may be configured to implement the steps in the method for receiving a reference signal in <FIG> of the foregoing embodiment, and functions of the apparatus embodiment in <FIG>. Functions to be implemented by the receiving unit <NUM> in <FIG> may be implemented by the transceiver <NUM> of the base station, or implemented by the transceiver <NUM> controlled by the processor <NUM>; functions to be implemented by the transmission unit <NUM> may also be implemented by the transceiver <NUM> of the base station, or may be implemented by the transceiver <NUM> controlled by the processor <NUM>; and functions to be implemented by the processing unit <NUM> may be implemented by the processor <NUM>.

In addition, the terminal device <NUM> and the base station <NUM> in this embodiment are further configured to implement all method procedures shown in <FIG> of the foregoing method embodiment. Further, the terminal device <NUM> is configured to implement all or some functions of the apparatus for transmitting a signal as shown in <FIG> of the foregoing apparatus embodiment, and the base station <NUM> is configured to implement all or some functions of the apparatus for receiving a signal as shown in <FIG> of the foregoing apparatus embodiment. Specifically, functions of all units may be implemented by corresponding transceivers and processors.

In a specific implementation, this application further provides a computer storage medium. The computer storage medium may store a program. When the program is executed, some or all steps included in the embodiments of the method for transmitting a reference signal, the method for receiving a reference signal, the method for transmitting a signal, and the method for receiving a signal according to this application may be performed. The storage medium may be a magnetic disk, an optical disc, a read-only memory (read-only memory, ROM), a random access memory (random access memory, RAM), or the like.

A person skilled in the art may clearly understand that, the technologies in the embodiments of this application may be implemented by software in addition to a necessary general hardware platform. Based on such an understanding, the technical solutions of this application essentially or the part contributing to the prior art may be implemented in a form of a software product. The software product is stored in a storage medium, such as a ROM/RAM, a hard disk, or an optical disc, and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform the methods described in the embodiments or some parts of the embodiments of this application.

For same or similar parts in the embodiments in the specification, mutual reference may be made. Especially, the foregoing embodiment is basically similar to a method embodiment, and therefore is described briefly; for related parts, reference may be made to descriptions in the method embodiment.

Claim 1:
A method for transmitting an uplink reference signal by a second network device, wherein the method comprises:
receiving (<NUM>), by the second network device, first group information of reference signal ports from a first network device, wherein the first group information comprises information about N groups of the reference signal ports, wherein port numbers comprised in any two of the N groups of the reference signal ports are different, N is a positive integer, and N><NUM>;
determining (<NUM>), by the second network device, a kth group of reference signal antenna ports in the N groups of reference signal ports, wherein k is a positive integer, and N≥k><NUM>; and
transmitting (<NUM>), by the second network device, a reference signal on the kth group of reference signal antenna ports, wherein the determining, by the second network device, a kth group of reference signal antenna ports in the N groups of reference signal ports comprises:
determining, by the second network device, the kth group of reference signal antenna ports according to an occasion for transmitting the reference signal, the group quantity N of the reference signal ports, and a quantity K of times that the reference signal is transmitted;
wherein the determining the kth group of reference signal antenna ports comprises:
according to the following relation: <MAT>
determining the antenna port group number k for the reference signal,
wherein <MAT>
n represents the occasion for transmitting the reference signal, k(n) represents the antenna port group number k determined for the reference signal at the occasion n, K represents the quantity of times that the reference signal is transmitted, and K≥<NUM>.