CN109075932B

CN109075932B - Reference signal configuration method, central unit and distribution unit

Info

Publication number: CN109075932B
Application number: CN201680085541.6A
Authority: CN
Inventors: 侯云; 招溢利
Original assignee: Huizhou TCL Mobile Communication Co Ltd
Current assignee: Huizhou TCL Mobile Communication Co Ltd
Priority date: 2016-08-31
Filing date: 2016-08-31
Publication date: 2022-03-01
Anticipated expiration: 2036-08-31
Also published as: WO2018039986A1; CN109075932A

Abstract

A reference signal configuration method is provided. The method comprises the following steps: a central unit determining whether to turn on or off a distribution unit within a coverage area of the central unit; wherein the central unit is connected to and controls a plurality of the distribution units; the central unit bears the upper layer in the air interface protocol stack, and the distribution unit bears the lower layer of the air interface protocol stack; and the central unit sends a reference signal configuration message to the distribution units so that the distribution units switch from stopping sending the reference signals to sending the corresponding reference signals or stop sending the reference signals in response to the reference signal configuration message. The application also discloses related central units and distribution units.

Description

Reference signal configuration method, central unit and distribution unit

Technical Field

Embodiments of the present invention relate generally to communication technologies, and more particularly, to a Reference Signal (RS) configuration method, a Central Unit (CU), and a Distributed Unit (DU).

Background

Today with the explosive growth of mobile communications, CU/DU architecture draws a lot of attention in order to meet the explosively growing mobile traffic and data volume demands. An exemplary example of a CU and DU is shown in fig. 1; in fig. 1, one CU connects and controls a plurality of DUs. Typically, the DUs carry the lower layers of the air interface protocol stack, while the CUs are used to carry the higher layers in a centralized manner for all DUs. A CU can implement more flexible DU networking (level) by simply controlling the on/off of DUs to reduce the management overhead of the DUs and facilitate coordination between different DUs, thereby reducing overall power consumption. The DU may also be referred to as a Transmission Point (TP), a Transmission and Reception Point (TRP), or a Radio Remote Head (RRH). A CU may also be referred to as a dedicated Baseband processing Unit (BBU), a centralized BBU, a centralized Radio Access Network (RAN) server, a cloud server, or a virtual base station based on a cloud-fabric Baseband pool.

User Equipment (UE) is typically connected to the nearest DU, which is likely to have good signal strength, to achieve higher data throughput. DU selection is required when the UE initiates a new data transmission within the coverage area of a CU or switches from a currently connected DU to another DU while maintaining the data connection. Therefore, for the DU selection in the above two cases, the UE needs to measure the reference signal sent by the DU to be measured to evaluate its signal strength/quality. In other words, each DU needs to send a DU-specific reference signal for UE to distinguish (distingguish) and measure.

In the prior art, a CU may turn off or turn on some DUs according to the access situation of the UE, the tidal effect, and the like. Each closed DU may enter an idle state where the UE is not connected to transmit data, but still needs to send a Discovery Reference Signal (DRS) for the UE to measure. DRS is a temporary sparse (sparse) version of a Cell-specific Reference Signal (Cell-specific Reference Signal), while DRS and CRS are always on and statically allocated, which may result in excessive power consumption waste. In addition, both DRS and CRS have only 6 different resource unit patterns, and correspond to different frequency offsets, respectively, and the different frequency offsets are designed to avoid collision between time-frequency resources used by adjacent DUs for transmitting RS. However, when the deployment density of the DUs is large, some adjacent DUs may need to use the same RE pattern, so that the time-frequency resources may collide with each other, thereby causing interference. Further, even if the closed DU uses a different RE pattern than the adjacent DU, the adjacent DU may transmit data using the same RE used by the DRS, and thus the DRS may interfere with data transmission.

Content of application

Embodiments of the present application provide a reference signal configuration method, a central unit, and a distribution unit, so as to solve problems in the prior art, such as excessive power consumption caused by a closed DU for sending a DRS, interference of an RS to an RS (RS-to-RS) and interference of the RS to data (RS-to-data), and the like.

The application provides a reference signal configuration method. The method comprises the following steps: a CU determines whether to turn on or off DUs within the CU's coverage area. Wherein the CU may connect and control a plurality of DUs; the CU may carry a higher layer in an air interface protocol stack and the DU may carry a lower layer in the air interface protocol stack; and the CU sends an RS configuration message to the DU, so that the DU responds to the RS configuration message to switch from the RS transmission stopping to the corresponding RS transmission or stop the RS transmission.

The RS configuration message for instructing the DU to stop transmitting RS may include: an Information Element (IE) for controlling the DU to stop sending the RS to enter a shutdown mode.

The RS configuration message for instructing the DU to transmit a corresponding RS may include related RS parameters; the related RS parameter includes at least one of a transmission period, a subframe offset, and a Resource Element (RE) pattern. The subframe offset may be used to indicate which subframes in the transmission period transmit corresponding RSs, and the RE pattern may be used to indicate a mapping manner of the corresponding RSs to the REs.

The RE pattern may be a CSI-RS class or a CRS class.

Determining whether to turn on or off DUs within the coverage area of the CU may include: the CU selects at least one access DU within the coverage area of the CU. Transmitting the RS configuration message to the DU may include: transmitting the RS configuration message to the at least one access DU in an off mode so that the at least one access DU can start transmitting the corresponding RS.

The RS configuration message may include a subframe offset; the subframe offset is mainly used by all DUs that currently send RSs.

Selecting the at least one access DU may include: selecting the at least one access DU within the coverage area at least according to the distribution of the DUs, so that the transmission range of the RS of the at least one access DU can cover the coverage area of the CU.

Selecting the at least one access DU may further include: the at least one access DU is selected only in closed DUs (DUs in closed mode).

Selecting the at least one access DU may further include: selecting the at least one access DU within the coverage area in response to a DU access request from the UE.

The method may further comprise: and sending the list of the at least one access DU and related RS parameters to the UE.

Determining whether to turn on or off the DU may include: the CU determines whether to open the DU in the coverage area according to the information of the first DU; wherein the first DU is a DU initially connected to at least one UE. Transmitting the RS configuration message to the DU may include: and the CU sends a first RS configuration message to the first DU, and sends a second RS configuration message to at least one closed DU in DUs adjacent to the first DU.

The first RS configuration message and the second RS configuration message may each include a subframe offset. The subframe offset included in the first RS configuration message may be the same as a subframe offset used before the first DU is connected to the at least one UE, and the subframe offset included in the second RS configuration message may be the same as the subframe offset included in the first RS configuration message.

Determining whether to turn on or off the DU may include: and the CU determines whether to open the DU in the coverage area according to the UE switching information in the coverage area, wherein the switching information comprises at least information of a source DU connected with the UE before switching and information of a target DU connected with the UE after switching. Transmitting the RS configuration message to the DU may include: when the source DU is not connected with any UE after being switched, the CU sends a candidate RS configuration message to the source DU; and when the target DU is not connected with any UE before switching, the CU sends a service RS configuration message to the target DU.

The candidate RS configuration message and the serving RS configuration message may each include a subframe offset. The subframe offset included in the candidate RS configuration message and the subframe offset in the serving RS configuration message may be the same as a subframe offset used before handover.

Determining whether to turn on or off the DU may include: the CU determines whether to close the DUs in the coverage area according to the information of the DUs to be closed, where the DUs to be closed include a DU in a closed mode (i.e., a closed DU), a DU in which all neighboring DUs are in a non-service mode (i.e., a DU in a non-service mode), and all connected UEs become idle or all service DUs that are switched to the coverage area of other CUs. Transmitting the RS configuration message to the DU may include: and the CU sends the RS configuration message to the DU to be closed so that the DU to be closed stops sending RS to enter a closing mode.

The CUs may be dedicated BBUs, centralized RAN servers, cloud servers, or virtual base stations based on cloud-fabric baseband pools. The DU may be TP, TRP or RRH

A reference signal configuration method is also provided. The method comprises the following steps: a DU receives an RS configuration message from a CU, wherein the CU can connect and control a plurality of DUs; the CU may carry a higher layer in an air interface protocol stack and the DU may carry a lower layer in the air interface protocol stack; and the DU switches from the RS transmission stop to the corresponding RS transmission or stops the RS transmission in response to the RS configuration message.

The RS configuration message for instructing the DU to stop transmitting RS may include: IE for controlling the DU to stop transmitting RS to enter a shutdown mode.

The RS configuration message for instructing the DU to transmit a corresponding RS may include related RS parameters; the related RS parameter may include at least one of a transmission period, a subframe offset, and an RE pattern. The subframe offset may be used to indicate which subframes in the transmission period transmit corresponding RSs, and the RE pattern may be used to indicate a mapping manner of the corresponding RSs to the REs.

The RE pattern may be a CSI-RS class or a CRS class.

The method may further comprise: and the DU sends a list of DUs to be tested and related RS parameters to the UE, wherein the list of the DUs to be tested comprises an access DU or a DU adjacent to the DU.

There is also provided a CU comprising: a determining module, configured to determine whether to turn on or turn off a DU in a coverage area of the CU, where the CU may connect and control a plurality of DUs; the CU may carry a higher layer in an air interface protocol stack and the DU may carry a lower layer in the air interface protocol stack; and a sending module, configured to send an RS configuration message to the DU, so that the DU switches from sending the RS being stopped to sending the corresponding RS in response to the RS configuration message, or stops sending the RS.

The determining module may be configured to select at least one access DU within the coverage area of the CU. The transmitting module may be configured to transmit the RS configuration message to the at least one access DU in a shutdown mode, so that the at least one access DU may start transmitting the corresponding RS.

The determining module may be configured to determine whether to turn on a DU in the coverage area according to information of the first DU; wherein the first DU may be a DU initially connected to at least one UE. The sending module may be configured to send a first RS configuration message to the first DU, and send a second RS configuration message to at least one closed DU in DUs adjacent to the first DU.

The determining module may be configured to determine whether to open a DU according to UE handover information in the coverage area, where the handover information may include at least information of a source DU connected to the UE before handover and information of a target DU connected to the UE after handover. The sending module may be configured to send a candidate RS configuration message to the source DU when the source DU is not connected to any UE after handover; and sending a service RS configuration message to the target DU when the target DU is not connected with any UE before the handover.

The determining module may be configured to determine whether to close the DU in the coverage area according to information of the DU to be closed. The DUs to be closed may include a DU set to be closed (i.e., a DU in a closed mode), a DU in which all neighboring DUs are in a non-service mode (i.e., a DU in a non-service mode), and a service DU in which all connected UEs become idle or switch to the coverage area of other CUs. The sending module may be configured to send the RS configuration message to the DU to be closed, so that the DU to be closed stops sending RS to enter a closing mode.

There is also provided a DU comprising: a receiving module, configured to receive an RS configuration message from a CU, where the CU may connect to and control a plurality of DUs; the CU may carry a higher layer in an air interface protocol stack and the DU may carry a lower layer in the air interface protocol stack; and a response module, configured to switch from sending the RS stop to sending the corresponding RS, or stop sending the RS, in response to the RS configuration message.

The RE pattern may be a CSI-RS class or a CRS class.

The DU may further include: and the sending module is used for sending the list of the DUs to be tested and the related RS parameters to the UE. The list of DUs to be measured may include an access DU or a DU adjacent to the DU.

There is also provided a CU comprising: comprising a processor and a transceiver connected to the processor. The processor may be configured to: determining whether to turn on or off DUs within a coverage area of the CU; transmitting, by the transceiver, an RS configuration message to the DU, so that the DU can switch from the stop of transmitting the RS to the transmission of the corresponding RS, or stop transmitting the RS, in response to the RS configuration message. Wherein the CU may connect and control a plurality of DUs; the CU may carry higher layers in the air interface protocol stack and the DU may carry lower layers of the air interface protocol stack.

The RE pattern may be a CSI-RS class or a CRS class.

The processor may be configured to: selecting at least one access DU within the coverage area of the CU; and transmitting, by the transceiver, the RS configuration message to the at least one access DU in a shutdown mode so that the at least one access DU can start transmitting the corresponding RS.

The processor may be configured to: selecting the at least one access DU within the coverage area at least according to the distribution of the DUs, so that the transmission range of the RS of the at least one access DU can cover the coverage area of the CU.

The processor may be configured to: the at least one access DU is selected only among the closed DUs.

The processor may be configured to: selecting the at least one access DU within the coverage area in response to a DU access request from the UE.

The processor may be further configured to: and sending the list of the at least one access DU and related RS parameters to the UE.

The processor may be configured to: determining whether to open the DU in the coverage area according to the information of the first DU; wherein, the first DU is a DU initially connected to at least one UE; and transmitting, by the transceiver, a first RS configuration message to the first DU, and transmitting a second RS configuration message to at least one closed DU among DUs adjacent to the first DU.

The first RS configuration message and the second RS configuration message may each include a subframe offset. Wherein the subframe offset included in the first RS configuration message may be the same as a subframe offset used before the first DU is connected to the at least one UE, and the subframe offset included in the second RS configuration message may be the same as the subframe offset included in the first RS configuration message.

The processor may be configured to: determining whether to open a DU in the coverage area according to UE handover information in the coverage area, wherein the handover information may include at least information of a source DU connected with the UE before handover and information of a target DU connected with the UE after handover; and when the source DU is not connected with any UE after the handover, sending a candidate RS configuration message to the source DU through the transceiver, and sending a service RS configuration message to the target DU when the source DU is in a candidate mode before the handover.

The processor may be configured to: determining whether to close the DUs in the coverage area according to the information of the DUs to be closed, wherein the DUs to be closed may include DUs set to be closed (i.e., DUs in a closed mode), DUs in which all adjacent DUs are in a non-service mode (i.e., DUs in a non-service mode), service DUs in which all connected UEs become idle or are switched to the coverage areas of other CUs; and sending the RS configuration message to the DU to be closed through the transceiver, so that the DU to be closed stops sending RS to enter a closing mode.

A CU may be a dedicated BBU, a centralized RAN server, a cloud server, or a virtual base station based on a cloud-fabric baseband pool. The DU may be TP, TRP or RRH

There is also provided a DU comprising: a processor and a transceiver connected to the processor. The processor may be configured to: receiving, by the transceiver, an RS configuration message from a CU; and switching from the stop of transmitting the RS to the transmission of the corresponding RS or stopping the transmission of the RS in response to the RS configuration message. Wherein the CU may connect and control a plurality of DUs; the CU may carry higher layers in the air interface protocol stack and the DU may carry lower layers of the air interface protocol stack.

The RE pattern may be a CSI-RS class or a CRS class.

The processor may be further configured to: and sending a list of DUs to be tested and related RS parameters to the UE, wherein the list of DUs to be tested can comprise access DUs or DUs adjacent to the DUs.

The advantages of the present application are as follows. The CU may send an RS configuration message to the DU so that the DU can switch between stopping sending RSs and sending corresponding RSs, so that the DU can send RSs when needed. Compared with the situation that all non-service DUs in the current LTE standard still transmit the DRS, the method for stopping transmitting the RS in the LTE standard can reduce power consumption. In addition, the DU which stops transmitting the RS does not need to occupy the RE pattern, thereby reducing the total number of DUs competing for the RE pattern, reducing the possibility of time-frequency resource conflict among different DUs and reducing the interference of the reference signal to the data.

Drawings

FIG. 1 is a schematic diagram showing a CU/DU architecture;

fig. 2 is a flow chart of a first embodiment of a reference signal configuration method according to the present application;

fig. 3 is a flow chart of a second embodiment of a reference signal configuration method according to the present application;

fig. 4 is a diagram illustrating selection of an access DU in a second embodiment of a reference signal configuration method;

fig. 5 is a flow chart of a third embodiment of a reference signal configuration method according to the present application;

fig. 6 is a flow chart of a fourth embodiment of a reference signal configuration method according to the present application;

fig. 7 is a flow chart of a fifth embodiment of a reference signal configuration method according to the present application;

fig. 8 is a schematic diagram of a DU switching between three operation modes according to an embodiment of a reference signal configuration method of the present application;

fig. 9 is a flowchart of a UE and a DU establishing connection in a case where there is no direct connection between the UE and a CU according to an embodiment of a reference signal configuration method according to the present application;

FIG. 10 is a flowchart illustrating a UE establishing a connection with a DU in the case that a direct connection exists between the UE and a CU according to an embodiment of a reference signal configuration method of the present application;

fig. 11 is a flow chart of a sixth embodiment of a reference signal configuration method according to the present application;

fig. 12 is a flowchart of a seventh embodiment of a reference signal configuration method according to the present application;

FIG. 13 is a block diagram of a first embodiment of a CU according to the subject application;

FIG. 14 is a block diagram of a second embodiment of a CU according to the subject application;

fig. 15 is a block diagram of a structure of a first embodiment of a DU according to the present application;

fig. 16 is a block diagram of the structure of a second embodiment of a DU according to the present application;

fig. 17 is a block diagram of the structure of a third embodiment of a DU according to the present application.

The present invention includes references to "one embodiment," a particular embodiment, "" some embodiments, "" different embodiments, "or" embodiments. The appearances of the phrase "one embodiment," "a particular embodiment," "some embodiments," "different embodiments," or "an embodiment" are not necessarily referring to the same embodiment. The particular features, structures or characteristics may be combined in a manner consistent with the invention.

Various modules, units, circuits, or other components may be described or claimed as being "configured to" perform a task or tasks. In these contexts, "configured to" is used to connote structure by indicating that the module/unit/circuit/component includes structure (e.g., circuitry) that performs these one or more tasks during operation. Thus, a module/unit/circuit/component may be said to be configured to perform a task even when the particular module/unit/circuit/component is currently inoperable (e.g., not in an on mode). A module/unit/circuit/component for use with the "configured to" language includes hardware-e.g., circuitry, memory storing program instructions executable to perform operations, and so on. For a module/unit/circuit/component, it is expressly not intended that the module/unit/circuit/component "configured to" perform one or more tasks cite 35u.s.c. § 112 (f). Additionally, "configured to" may include a general-purpose structure (e.g., a general-purpose circuit) that is packaged by software and/or firmware (e.g., an FPGA or a general-purpose processor executing software) to operate in a manner that enables performance of the task in question. "configured to" may also include adapting a process flow (e.g., a semiconductor fabrication facility) to a fabrication facility (e.g., an integrated circuit) for performing or carrying out one or more tasks.

As used herein, the term "based on" describes one or more factors that affect the judgment. The term does not exclude additional factors that may influence the determination. That is, the determination may be based solely on these factors or at least in part on these factors. Consider the phrase "judge A based on B". When in this case, B is a factor that affects the judgment of a, such a phrase does not exclude that a is also judged based on C. In other cases, a may be judged based on B alone.

Detailed Description

Referring to fig. 2, fig. 2 depicts a first embodiment of a reference signal configuration method. For ease of illustration, the method is described sequentially. However, portions of the invention may be performed in other orders, or in parallel (e.g., concurrently). The method may be performed by a CU comprising a central controller, such as a dedicated Baseband processing Unit (BBU), a centralized BBU, a centralized Radio Access Network (RAN) server, a cloud server, or a virtual base station based on a cloud-based Baseband pool. The CU may carry higher Protocol layers in an air interface Protocol stack, such as Packet Data Convergence Protocol (PDCP), and the like. In general, the CUs are also responsible for communication with the core network. The method comprises the following steps.

In S11, the CU may determine whether to turn on or off Distribution Units (DUs) within the CU' S coverage area.

The DU may be a Transmission Point (TP), a Transmission and Reception Point (TRP), or a Radio Remote Head (RRH). Generally, whether to turn on or turn off the DU is determined according to access requirements of the UE. In particular, the DU of the connected UE, which has a high probability of connection (e.g., the DU adjacent to the DU of the connected UE), may be opened. Conversely, the DUs with less chance of connecting to the UE will be turned off. CUs may also turn DUs on or off depending on other needs or conditions. The UE may be fixed or mobile from place to place and may be, for example, without limitation, a cellular phone, a Personal Digital Assistant (PDA), a wireless modem, a tablet, a laptop, a cordless phone, or the like.

In S12, the CU may send a reference signal configuration message to the DU.

The operation mode of the DU can be divided into on and off according to whether the reference signal is transmitted or not. The DU in the on mode may transmit the SR every subframe or every several subframes. In response to the reference signal configuration message, the DU may switch between an on mode and an off mode. Specifically, the DU may switch from stopping transmission of the reference signal to transmitting the corresponding reference signal, or from transmitting the reference signal to stopping transmission of the reference signal. For the open DUs (i.e., the DUs are in the open mode), the DUs can be further divided into serving DUs and candidate DUs, i.e., DUs in the serving mode and the candidate mode, according to whether the UE is connected to transmit data.

The serving DU (i.e., UE-connected DU) may transmit the reference signal more frequently than the candidate DU (i.e., UE-unconnected DU). That is, the period for which the serving DU transmits the reference signal may be smaller than the candidate DU. When the DU is turned on, the DU may dynamically adjust the transmitted reference signal parameters in response to the reference signal configuration message.

A CU may send a reference signal configuration message only to DUs that need to start or stop sending reference signals or for which reference signal parameters change. Alternatively, a CU may uniformly send a reference signal configuration message to all DUs.

According to this embodiment, the CU may transmit a reference signal configuration message to the DU to switch the DU between stopping transmission of the reference signal and transmitting the corresponding reference signal, so that the DU may transmit the reference signal only when necessary, thereby implementing event-triggered transmission of the reference signal. Compared with the prior art in which all DUs in the shutdown mode are still in the shutdown mode of transmitting DRSs, stopping transmitting reference signals in the present application is more energy-saving. In addition, the DU which stops sending the reference signal does not need to occupy the RE pattern, thereby reducing the total number of DUs competing for the RE pattern, reducing the possibility of time-frequency resource conflict among different DUs and reducing the interference of the reference signal to data.

In a particular embodiment, the reference signal configuration message includes reference signal parameter configuration signaling and shutdown signaling. The shutdown signaling is used to instruct (instruction) the DU to stop sending the reference signal, and includes a shutdown element (IE) for controlling the DU to stop sending the reference signal to enter a shutdown mode. The reference signal parameter configuration signaling is used to instruct the DU to transmit a corresponding reference signal, including related reference signal parameters. Alternatively, the reference signal configuration message may include only one control signaling or a plurality of control signaling.

The related reference signal parameter may include at least one of a transmission period, a subframe offset, and an RE pattern. The subframe offset can be used to indicate which subframes in the transmission period transmit the corresponding reference signals, and the RE pattern can be used to indicate the mapping manner of the corresponding reference signals to the REs. The RE pattern may be CSI-RS (CSI-RS-like) or CRS (CRS-like) like. The CSI-RS type is a mapping method using a Channel State Information Reference Signal (CSI-RS), and the CRS type is a mapping method using a Cell-specific Reference Signal (CRS). Of course, the mapping method is not limited to the above-described method, and other suitable mapping methods may be used.

In the existing LTE/LTE-a standard, both CRS/DRS and CSI-RS can be measured by the UE, thus serving as the basis for DU selection. In terms of RE patterns of CRS, there are 6 different RE patterns according to the Physical Cell ID (PCI) of the BS and the result of the mod function of 6. CRS is transmitted on each subframe per Resource Block (RB), while the transmission period of DRS is 40-160 subframes. In terms of CSI-RS, there are a total of 40 possible RE positions for CSI-RS to use in RB pairs (RB-pair). Out of 40 possible RE locations (out of), each CSI-RS may take 2, 4 or 8 REs, depending on the number of antenna ports used. Thus, there are a total of up to 20 RE patterns, or so-called CSI-RS configurations. However, which CSI configuration to use is determined by the antenna port measurements. Therefore, the RE pattern for CSI-RS is fixed once the antenna ports are determined. Wherein, the transmission period of the CSI-RS is usually 5-80 subframes.

The transmission period of the reference signal can be determined by referring to the CRS/DRS or CSI-RS in the existing standard, or can be set by itself.

Under the environment with higher deployment density of DUs, if adjacent DUs need to use the same RE pattern and the reference signal period is the same, different DUs can send reference signals in different subframes by setting different subframe offsets, thereby avoiding time-frequency resource collision possibly caused by limited kinds of RE patterns and reducing interference. However, different subframe offsets may increase the total number of subframes that the UE needs to measure, resulting in increased power consumption. By introducing the RE patterns of the CSI-RS class, the number of classes of RE patterns can be increased, thereby greatly reducing the probability of occurrence of a situation where adjacent DUs need to use the same RE pattern. At this time, the adjacent DUs can use the same subframe offset and transmission period, so that the total number of subframes that the UE needs to measure is reduced, thereby reducing power consumption. Of course, different subframe offsets and/or transmission periods may be used.

Now referring to fig. 3, fig. 3 illustrates a second embodiment of the reference signal configuration method, which is to open the DU by selecting access to the DU based on the first embodiment of the reference signal configuration method. For ease of illustration, the method is described sequentially. However, portions of the invention may be performed in other orders, or in parallel (e.g., concurrently). This embodiment is an extension of the first embodiment, and therefore the same contents as those in the first embodiment of the reference signal configuration method of the present application are not described herein again. The method discussed below may include the following steps.

In S111, a CU may select at least one access DU within the coverage area of the CU.

When the UE does not establish a data connection with any DU, e.g. when the DU has just been powered on or is in idle mode, a set of DUs may be measured and a DU may be selected for the connection. The set of DUs that are intended for measurements by UEs that are not connected to any DU is called an access DU.

The CU may select at least one access DU within the coverage area based at least on the distribution of the DUs, such that the transmission range of the reference signal of the at least one access DU covers the entire coverage area of the CU, thereby enabling a UE requiring DU access anywhere within the coverage area to detect the reference signal transmitted by the at least one access DU. For example, as shown in fig. 4, assuming that all DUs in the coverage area of the CU are not connected to any UE, three DUs enclosed by the dashed boxes are selected as access DUs, which are in the on mode and transmit reference signals for the UE to measure; while the remaining DUs are in the shutdown mode. A CU may only select to access DUs in closed DUs. Alternatively, the selection range may be listed as the DU that is turned on.

In S112, the CU may transmit a reference signal configuration message to the access DU in the off mode, so that the access DU may start transmitting a corresponding reference signal to enter the candidate mode.

The CU may also send a reference signal configuration message to the access DU in the on mode, so that the access DU may adjust the sent reference signal parameters according to the reference signal configuration message.

The reference signal configuration message may include a subframe offset that is mainly used by all DUs that are currently in the candidate and serving modes to reduce the total number of subframes that the UE needs to measure.

Now referring to fig. 5, fig. 5 illustrates a third embodiment of the reference signal configuration method of the present application, which is based on the first embodiment of the reference signal configuration method of the present application, and the first DU is opened by acquiring information of the first DU. For ease of illustration, the method is described sequentially. However, portions of the invention may be performed in other orders, or in parallel (e.g., concurrently). This embodiment is an extension of the first embodiment of the reference signal configuration method of the present application, and therefore, the same contents as those in the first embodiment of the reference signal configuration method of the present application are not described herein again. The method in question may include the following steps.

In S121, the CU may determine whether to turn on a DU in the coverage area according to information of the first DU in the coverage area.

The first DU may be a DU initially connected to at least one UE. In general, the first DU may be a candidate DU before connecting at least one UE. In some cases, e.g. when there is a direct connection between the UE and the CU, then the first DU may be a DU that was in off-mode before connecting at least one UE. The CU may control the first DU to enter service mode and open DUs adjacent to the first DU. It is understood that the first DU may enter the service mode by itself.

In S122, the CU may send a first reference signal configuration message to a first DU, and send a second reference signal configuration message to a closed DU of at least one DU adjacent to the first DU.

The first DU may enter a service mode in response to the first reference signal configuration message, and closed DUs among DUs adjacent to the first DU may enter a candidate mode in response to the second reference signal configuration message. For the opened DU in the DUs adjacent to the first DU, the CU may not send the reference signal configuration message, or may also send the reference configuration information, for example, to modify its reference signal parameters to match the first DU.

The transmission period included in the first reference signal configuration message may be smaller than the transmission period included in the second reference signal configuration message. Further, the transmission period included in the first reference signal configuration message may be an integer multiple of the transmission period included in the second reference signal configuration message. Optionally, the transmission period included in the first reference signal configuration message may also be the same as the transmission period included in the second reference signal configuration message.

The first and second reference signal configuration messages may each include a subframe offset. The subframe offset included in the first reference signal configuration message may be the same as a subframe offset used before the first DU connects the at least one UE (i.e., when the first UE is in the candidate mode), and the subframe offset included in the second reference signal configuration message may be the same as the subframe offset included in the first reference signal configuration message, so that the total number of subframes that the UE needs to measure may be reduced.

Now referring to fig. 6, fig. 6 illustrates a fourth embodiment of the reference signal configuration method of the present application, which is based on the first embodiment of the reference signal configuration method of the present application, and the DU is opened by acquiring UE handover (switch) information between different DUs in the coverage area. For ease of illustration, the method is described sequentially. However, portions of the invention may be performed in other orders, or in parallel (e.g., concurrently). This embodiment is an extension of the first embodiment of the reference signal configuration method of the present application, and therefore, the same contents as those in the first embodiment of the reference signal configuration method of the present application are not described herein again. The method in question may include the following steps.

In S131, the CU may determine whether to turn on a DU within the coverage area according to the UE handover information within the coverage area.

The handover information may include information of at least a Source (Source) DU connected to the UE before handover and information of a Target (Target) DU connected to the UE after handover. In general, the target DU is adjacent to the source DU.

In S132, if the source DU is not connected to any UE after the handover, the CU may send a candidate reference signal configuration message to the source DU; the CU may send a service reference signal configuration message to the target DU if the target DU is not connected to any UE before handover.

In general, the source DU may be in service mode before handover. Therefore, if the source DU is not connected to any UE after the UE handover, the CU may need to send a candidate reference signal configuration message to the source DU to switch the source DU from the serving mode to the candidate mode since the source DU is adjacent to the target DU. It will be appreciated that the source DU can switch from the service mode to the candidate mode on its own as needed. In some embodiments, a CU may turn off a source DU if the source DU is not adjacent to a target DU.

In general, the target DU is in service mode after the UE handover. Thus, if the target DU is not connected with any UE (i.e., in the candidate mode) before the UE handover, the CU may need to send a service reference signal configuration message to the target DU to switch the target DU from the candidate mode to the service mode.

If the source DU is in service mode after the UE handover or the target DU is in service mode before the UE handover, the CU may choose not to send the reference signal configuration message, or may also choose to send the reference signal configuration message to modify the reference signal parameters of the source DU and/or the target DU.

The transmission period included in the candidate reference signal configuration message may be greater than the transmission period included in the serving reference signal configuration message. Further, the transmission period included in the candidate reference signal configuration message may be an integer multiple of the transmission period included in the serving reference signal configuration message. Optionally, the transmission period included in the candidate reference signal configuration message may also be the same as the transmission period included in the service reference signal configuration message.

The candidate reference signal configuration message and the serving reference signal configuration message may each include a subframe offset. The subframe offset in the candidate reference signal configuration message is the same as the subframe offset used when the source DU is in service mode (i.e., before handover). The subframe offset in the serving reference signal configuration message is the same as the subframe offset used when the target DU is in the candidate mode.

Now referring to fig. 7, fig. 7 illustrates a fifth embodiment of the reference signal configuration method of the present application, which is to close a DU by acquiring information of the DU to be closed based on the first embodiment of the reference signal configuration method of the present application. This embodiment is an extension of the first embodiment of the reference signal configuration method of the present application, and therefore, the same contents as those in the first embodiment of the reference signal configuration method of the present application are not described herein again. The method in question may include the following steps.

In S141, the CU may determine whether to close the DU in the coverage area according to the information of the DU to be closed.

The DUs to be closed may include DUs set to be in closed mode (i.e., closed DUs), candidate DUs for which all neighboring DUs are in non-service mode, and serving DUs for which all connected UEs become idle mode or handover (handover) to the coverage area of other CUs. The CU may release the reference signal parameters occupied by the DU to be closed, i.e., may reallocate the same reference signal parameters used by the DU to be closed to other DUs.

In S142, the CU may transmit a reference signal configuration message to the DU to be turned off.

In this way, the DU to be shut down may stop transmitting the reference signal and enter a shut down mode.

In a specific embodiment, a CU may switch a DU between three operating modes by sending a reference signal configuration message to the DU, the switching conditions being specifically shown in fig. 8. In summary, the principle of determining which operation mode the DU is in is as follows: DUs connected to a UE are in service mode, DUs that are not connected to any UE but are likely to establish a connection with a UE and therefore need to be measured by the UE are in candidate mode, whereas DUs that do not fulfill the candidate mode and service mode conditions (i.e. are not connected to and do not need to be measured by any UE) are in shutdown mode.

Specifically, as shown in fig. 8, for a service DU (i.e., a DU connected to a UE and thus in service mode), if all connected UEs become idle mode or handover (handover) to the coverage area of other CUs, the service DU will be turned off and thus enter the off mode. Conversely, if the serving DU does not serve any UE and at least one connected UE switches to an adjacent DU, e.g. a partially connected UE enters idle mode or switches (handover) to the coverage area of other CUs and at least one UE switches to an adjacent DU, or all connected UEs switch to an adjacent DU, the serving DU will become a candidate mode. Subsequently, for a candidate DU, if there is any UE attempting to access the DU and then successfully connecting with the DU, the candidate DU becomes a serving DU. On the other hand, if there is no adjacent DU in the service mode (case a), or if the candidate DU is set to the shutdown mode (case b), the candidate DU becomes a shutdown DU. Here, the candidate DU being set to the off mode means that the candidate DU is deleted from the list of access DUs. For the closed DU, if there is any adjacent DU in the service mode (case a), or if the closed DU is set as an access DU (case b), the closed DU becomes a candidate DU.

It is noted that the DU can be switched between service mode and candidate mode either under the instruction of the CU or by itself. When the DU switches between the service mode and the candidate mode, the CU will not send a reference signal configuration message to the DU if the reference signal parameters used in the service mode are the same as those used in the candidate mode.

In this embodiment, the DUs that need to be measured by the UE include access DUs and DUs adjacent to the serving DU. In some embodiments, the DUs that need to be measured by the UE may also include only access DUs or DUs that are adjacent to the serving DU. Alternatively, the DUs adjacent to the serving DU may be replaced by DUs whose distance from the first DU is smaller than a preset value.

It should be noted that, in addition to sending the reference signal configuration message, the CU may need to inform the UE of the list of DUs to be tested and the related reference signal parameters. The above procedure of sending the list of DUs to be measured and the reference signal parameters can be divided into two types according to whether there is a direct connection between the UE and the CU, mainly differing in whether the list of DUs to be measured and the related reference signal parameters are sent by the CU or the DU. For a UE that does not establish a connection with a DU, the list of DUs to be tested may refer to the list of access DUs. For a UE that has established a connection with a DU, the list of DUs to be tested may refer to a list of DUs adjacent to the currently connected DU.

For example, fig. 9 shows a specific procedure of establishing a connection between a UE and a DU in a case where there is no direct connection between the UE and the CU. This procedure applies to the following cases: for example, a CU is not equipped with an antenna, thereby causing the CU to be unable to establish a direct connection with a UE; or the UE has not established a connection with the CU, etc. Therefore, the CU needs to send the list of access DUs and the associated reference signal parameters to the DUs, and the DUs then send the list of access DUs and the associated reference signal parameters in the system information to the UE. The UE may read the system information to obtain a list of access DUs and associated reference signal parameters and thereby detect and select a DU, and then synchronize to the selected DU for random access, so that the connection between the UE and the DU can then be completed.

Fig. 10 shows a specific procedure for establishing a connection between a UE and a DU in a case where there is a direct connection between the UE and the CU. The procedure is applicable to the case where the UE and the CU maintain a connection and are in an idle state with the DU. Thus, as shown in the figure, a CU can select to access a DU within the coverage area in response to a DU access request from a UE, or select to access a DU by itself without receiving any request from a UE. The CU may then send the list of access DUs and the related reference signal parameters directly to the UE, e.g. by using an RRC connection reconfiguration message in the LTE/LTE-a standard. The UE may receive the list of access DUs and the associated reference signal parameters and thereby detect and select a DU, and then synchronize to the selected DU for random access, so that the connection between the UE and the DU can then be completed. The random access here is only between the UE and the DU, since there is already a connection between the UE and the CU. After the UE and the DU are connected, the CU and the UE-connected DU may cooperate to operate in dual connectivity or carrier aggregation mode.

The step of the CU sending the dedicated reference signal configuration message to the DU is not shown in both fig. 9 and fig. 10, because the CU may choose not to send the reference signal configuration message to the access DU, assuming that the access DUs that the CU selects are all open DUs. If the CU sends a reference signal configuration message to the DU, this step should be performed before the step of the CU or DU sending the list of access DUs and the associated reference signal parameters to the UE.

After the UE completes establishing a connection (including initial access and handover) with the selected DU, the CU may need to send a list of DUs to be tested and related reference signal parameters to the UE directly or through the selected DU, in addition to controlling the selected DU and DUs adjacent to the selected DU to perform necessary working mode handover; wherein, the DU to be tested refers to the DU adjacent to the selected DU.

Fig. 11 shows a sixth embodiment of a reference information configuration method according to the present application, which is performed by a DU carrying a lower protocol layer in an air interface protocol stack. For ease of illustration, the method is described sequentially. However, portions of the invention may be performed in other orders, or in parallel (e.g., concurrently). Although it has not been determined how the air interface protocol stack is divided between CUs and DUs, it has been agreed that DUs will carry at least the physical layer. The method may include the following steps.

In S21, the DU may receive a reference signal configuration message from the CU.

The operation mode of the DU can be divided into on and off according to whether the reference signal is transmitted or not. For the open DUs, the DU can be further divided into a serving DU and a candidate DU, i.e., a DU in a serving mode or a candidate mode, depending on whether the UE is connected for data transmission. The frequency of the DU transmission reference signal in the service mode (i.e., UE-connected) may be higher than the frequency of the DU transmission reference signal in the candidate mode (i.e., UE-unconnected). That is, the period for the serving DU to transmit the reference signal may be smaller than the period for the candidate DU to transmit the reference signal. The reference signal configuration message from the CU may be received through an interface configured between the CU and the DU, regardless of the operation mode of the DU.

In S22, the DU switches from stopping transmission of the reference signal to transmitting the corresponding reference signal or stops transmission of the reference signal in response to the reference signal configuration message.

When the DU is in the on mode, the reference signal transmission may be stopped in response to a reference signal configuration message, or the transmitted reference signal parameters may be dynamically adjusted, for example, to switch between the candidate mode and the service mode. When a DU is in the shutdown mode, transmission of a corresponding reference signal may be started in response to a reference signal configuration message.

According to an embodiment of the above-described embodiments, a CU may transmit a reference signal configuration message to a DU such that the DU switches between stopping transmission of reference signals and transmitting corresponding reference signals. Accordingly, the DU can transmit the reference signal only when necessary, thereby implementing the event-triggered reference signal transmission. Compared with the prior art that all closed DUs still transmit DRSs, the method for stopping transmitting reference signals in the application is more energy-saving. In addition, the DU that stops transmitting the reference signal does not occupy the RE pattern, resulting in a reduction of the total number of DUs competing for the RE pattern, thereby reducing the possibility of time-frequency resource collision between different DUs and reducing the interference of the reference signal to data (RS-to-data).

Now referring to fig. 12, fig. 12 illustrates a seventh embodiment of the reference signal configuration method of the present application, which is based on the sixth embodiment of the reference signal configuration method of the present application, and further includes the following steps.

In S23, the DU may send a list of DUs to be tested and associated reference signal parameters to the UE.

In step S22, if DU switches from off mode to on mode, the execution of this step should be after step S22. Before performing this step, the DU may generally receive a list of DUs to be measured and associated reference signal parameters from the CU. The order between receiving the list of DUs to be measured and the associated reference signal parameters and receiving the reference signal configuration message from the CU is not limited.

The list of DUs to be tested may include an access DU and DUs adjacent to the access DU. For a UE that does not establish a connection with the DU, the list of DUs to be tested may refer to the list of access DUs. For a UE that has established a connection with this DU, the list of DUs to be measured may refer to the list of DUs adjacent to the currently connected DU.

Referring now to FIG. 13, FIG. 13 depicts a block diagram of a first embodiment of a CU. The CU may comprise a determining module 11 and a sending module 12.

The determining module 11 may be configured to determine whether to turn on or turn off a DU in a coverage area of a CU. A CU may connect and control multiple DUs, and the CU may carry higher layers in an air interface protocol stack, and the DU may carry lower layers in the air interface protocol stack.

The sending module 12 may be configured to send a reference signal configuration message to the DU, so that the DU may switch from stopping sending the reference signal to sending the corresponding reference signal or stop sending the reference signal in response to the reference signal configuration message.

In particular, the determining module 11 may be configured to select at least one access DU within the coverage area of the CU. The sending module 12 is configured to send a reference signal configuration message to at least one access DU in the shutdown mode, so that the access DU starts sending a corresponding reference signal to enter the candidate mode.

Specifically, the determining module 11 may be configured to determine whether to turn on a DU in the coverage area according to information of a first DU in the coverage area. Wherein, the first DU is a DU initially connected to at least one UE. The sending module 12 may be configured to send a first reference signal configuration message to a first DU, and send a second reference signal configuration message to at least one closed DU in DUs adjacent to the first DU.

Specifically, the determining module 11 may be configured to determine whether to turn on the DU according to UE handover information in the coverage area. The handover information may include at least information of a source DU connected to the UE before handover and information of a target DU connected to the UE after handover. The sending module 12 is configured to send the candidate reference signal configuration message to the source DU when the source DU is not connected to any UE after the handover, and send the service reference signal configuration message to the target DU when the target DU is not connected to any UE before the handover.

Specifically, the determining module 11 may be configured to determine whether to close the DU in the coverage area according to the information of the DU to be closed. Wherein, the DUs to be closed include the DU set to be closed, the candidate DUs in which all the neighboring DUs are in the non-service mode, and the service DU in which all the connected UEs become idle mode or handover (handover) to the coverage area of other CUs. The sending module 12 may be configured to send a reference signal configuration message to the DU to be turned off, so that the DU stops sending reference signals to enter the turn-off mode.

Referring now to FIG. 14, FIG. 14 is a block diagram of a second embodiment of a CU. The CU may include a processor 110 and a transceiver 120. The transceiver 120 may be connected to the processor 110 through a bus.

Transceiver 120 may be used to send and receive data and is the interface that CUs communicate with other communication devices.

The processor 110 may control the operation of the CU, and the processor 110 may also be referred to as a CPU (Central Processing Unit). The Processor 110 may be an Integrated Circuit chip with Signal processing capabilities, such as a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate, transistor logic, or discrete hardware component. The general purpose processor may be a microprocessor or any conventional processor.

The CU can further include a memory (not shown) for storing instructions and data necessary for processor 110 to operate. The memory may also store data received by the transceiver 120.

The processor 110 may be configured to: determining whether to turn on or off a DU in a coverage area; the reference signal configuration message is transmitted to the DU through the transceiver 120, so that the DU switches from stopping transmission of the reference signal to transmitting the corresponding reference signal or stops transmission of the reference signal in response to the reference signal configuration message. Wherein a CU can connect and control a plurality of DUs. A CU may carry higher layers in the air interface protocol stack and a DU may carry lower layers in the air interface protocol stack.

The reference signal configuration message for instructing the DU to stop transmitting the reference signal includes an Information Element (IE) for controlling the DU to stop transmitting the reference signal to enter the off mode.

The reference signal configuration message for instructing the DU to transmit a corresponding reference signal may include related reference signal parameters. Wherein the related reference signal parameter may include at least one of a transmission period, a subframe offset, and an RE pattern. The subframe offset may be used to indicate which subframes in the transmission period transmit the corresponding reference signals, and the RE pattern may be used to indicate a mapping manner of the corresponding reference signals to the REs.

The RE patterns may be CSI-RS class or CRS class.

The processor 110 may be configured to: selecting at least one access DU within a coverage area of the CU; and transmitting, by the transceiver, a reference signal configuration message to the at least one access DU in the off mode so that the access DU can start transmitting a corresponding reference signal to enter the candidate mode.

The reference signal configuration message may include a subframe offset that is primarily used by all DUs that are currently in the candidate mode and the serving mode.

In particular, the processor 110 may be configured to select at least one access DU within the coverage area at least according to the distribution of the DUs, such that the transmission range of the reference signal of the at least one access DU can cover the coverage area of the CU.

In particular, the processor 110 may be configured to select at least one access DU only among the closed DUs.

In particular, the processor 110 may be further configured to select at least one access DU within the coverage area in response to the DU access request from the UE.

In particular, the processor 110 may be further configured to send a list of at least one access DU and related reference signal parameters to the UE.

In particular, the processor 110 may be configured to: determining whether to start a DU in a coverage area according to information of a first DU in the coverage area, wherein the first DU is a DU initially connected with at least one UE; the first reference signal configuration message is transmitted to the first DU and the second reference signal configuration message is transmitted to at least one closed DU among DUs adjacent to the first DU through the transceiver 120.

Specifically, the first reference signal configuration message and the second reference signal configuration message each include a subframe offset. The subframe offset included in the first reference signal configuration message may be the same as a subframe offset used before the first DU connects at least one UE, and the subframe offset included in the second reference signal configuration message may be the same as a subframe offset included in the first reference signal configuration message.

In particular, the processor 110 may be configured to: determining whether to start a DU in a coverage area according to UE switching information in the coverage area, wherein the switching information comprises at least information of a source DU connected with the UE before switching and information of a target DU connected with the UE after switching; and transmitting, by the transceiver, the candidate reference signal configuration message to the source DU when the source DU is not connected to any UE after the handover, and transmitting the service reference signal configuration message to the target DU when the target DU is not connected to any UE before the handover.

In particular, the candidate reference signal configuration message and the serving reference signal configuration message may each include a subframe offset. The subframe offset included in the candidate reference signal configuration message and the serving reference signal configuration message may be the same as the subframe offset used before the handover.

In particular, the processor 110 may be configured to: determining whether to close the DUs in the coverage area according to the information of the DUs to be closed, wherein the DUs to be closed can comprise the DUs set to be closed, candidate DUs of which all adjacent DUs are in a non-service mode, and service DUs of which all connected UEs become an idle mode or are switched to the coverage areas of other CUs; and transmitting, by the transceiver, a reference signal configuration message to the DU to be shut down, so that the DU to be shut down stops transmitting the reference signal to enter a shut down mode.

The CU may be a dedicated Baseband processing Unit (BBU), a centralized BBU, a centralized Radio Access Network (RAN) server, a cloud server, or a virtual base station based on a cloud-based Baseband pool. The DU may be a Transmission Point (TP), a Transmission and Reception Point (TRP), or a Radio Remote Head (RRH).

The functions of the respective components of the CU according to the present embodiment may refer to the relevant description in the corresponding method embodiment, and will not be repeated here.

Referring now to fig. 15, fig. 15 depicts a block diagram of a first embodiment of a DU. The DU may comprise a receiving module 21 and a response module 22.

The receiving module 21 may be configured to receive a reference signal configuration message from a CU. Wherein a CU can connect and control a plurality of DUs. In general, the DUs are used to carry lower layers in the air interface protocol stack, while the CUs are responsible for carrying higher layers in a centralized manner for all DUs.

The response module 22 may be configured to switch from ceasing to transmit the reference signal to transmitting the corresponding reference signal, or to cease to transmit the reference signal, in response to the reference signal configuration message.

Now referring to fig. 16, fig. 16 illustrates a second embodiment of the DU, which is based on the first embodiment of the DU and further includes a sending module 23.

The sending module 23 may be configured to send a list of DUs to be measured and related reference signal parameters to the UE. The list of DUs to be measured may include access DUs or DUs adjacent to the DUs.

Specifically, the reference signal configuration message for instructing the DU to stop transmitting the reference signal may include an IE for controlling the DU to stop transmitting the reference signal to enter the off mode.

Specifically, the reference signal configuration message for instructing the DU to transmit the corresponding reference signal may include related reference signal parameters; wherein the related reference signal parameter may include at least one of a transmission period, a subframe offset, and an RE pattern. The subframe offset may be used to indicate which subframes in the transmission period transmit the corresponding reference signals, and the RE pattern may be used to indicate a mapping manner of the corresponding reference signals to the REs.

In particular, the RE pattern may be CSI-RS class or CRS class.

Referring now to fig. 17, a third embodiment of the DU may include: a processor 210 and a transceiver 2200 connected to the processor 210 through a bus.

Transceiver 220 may be used to transmit and receive data and is the interface by which the DUs communicate with other communication devices.

The processor 210 may control the operation of the DU, and the processor 210 may also be referred to as a CPU (Central Processing Unit). The Processor 210 may be an Integrated Circuit chip with Signal processing capabilities, such as a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate, transistor logic, or discrete hardware component. The general purpose processor may be a microprocessor or any conventional processor.

The DU may further include a memory (not shown) for storing instructions and data necessary for the operation of the processor 210. The memory may also store data received by the transceiver 220.

The processor 210 may be configured to: receiving, by transceiver 220, a reference signal configuration message from a CU; and switching from ceasing to transmit the reference signal to transmitting the corresponding reference signal, or ceasing to transmit the reference signal, in response to the reference signal configuration message. Wherein a CU can connect and control a plurality of DUs. In general, DUs can be used to carry lower layers in the air interface protocol stack, while CUs are responsible for carrying higher layers in a centralized manner for all DUs.

Specifically, the reference signal configuration message for instructing the DU to transmit the corresponding reference signal may include related reference signal parameters; wherein the related reference signal parameter may include at least one of a transmission period, a subframe offset, and an RE pattern. The subframe offset may be used to indicate which subframes in the transmission period transmit the corresponding reference signals, and the RE pattern is used to indicate a mapping manner of the corresponding reference signals to the REs.

Specifically, the RE pattern is of the CSI-RS class or the CRS class.

The processor 210 may also be configured to send a list of DUs to be tested and associated reference signal parameters to the UE. The list of DUs to be measured may include access DUs or DUs adjacent to the DUs.

The functions of the respective components of the DU according to the present embodiment may refer to the related descriptions in the corresponding method embodiments, and are not repeated here.

It should be understood that the disclosed CU, DU, and method may be implemented in other ways as well. Of course, the above-described CUs and DUs are merely illustrative, and for example, the division of a module or unit is only one logical functional division, and there may be other divisions when actually implemented, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be realized through some interfaces, devices or units, and the indirect coupling or communication connection may be in an electrical mechanical or other form.

The separate units described may or may not be physically separate units. Components shown as units may or may not be physical units and may be located at one location or may be distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the invention.

In addition, each functional unit discussed in the present invention may be integrated into one processing unit, or each unit may exist separately and physically, and two or more units may be integrated into one unit. The integrated unit can be realized by hardware or a software functional unit.

If the integrated unit is implemented as a software functional unit and sold or used as a separate product, it may be stored in a computer readable storage medium. Based on such understanding, the essential technical solution of the present invention or all or part of the technical solution may be implemented as a software product. A computer software product may be stored in a storage medium and may include instructions that cause a computing device (e.g., a personal computer, server, or network device, etc.) or processor to perform all or part of the methods described herein. The storage medium may include all kinds of media that can store program codes, for example, a USB flash disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and the like.

The above description is only some exemplary embodiments of the present invention, and does not limit the scope of the present invention. Any equivalent structure or equivalent flow transformation made by the invention or any direct or indirect application of the invention in other related technical fields shall be included in the scope of the patent protection of the invention.

Claims

1. A method for reference signal configuration, comprising:

a central unit determining whether to turn on or off a distribution unit within a coverage area of the central unit; wherein the central unit is connected to and controls a plurality of the distribution units; the central unit bears the upper layer in the air interface protocol stack, and the distribution unit bears the lower layer of the air interface protocol stack; and

the central unit sends a reference signal configuration message to the distribution units, so that the distribution units switch from stopping sending the reference signals to sending the corresponding reference signals or stop sending the reference signals in response to the reference signal configuration message.

2. The method of claim 1, wherein the reference signal configuration message for instructing the distribution unit to stop sending reference signals comprises: a cell for controlling the distribution unit to stop sending reference signals to enter a shutdown mode.

3. The method of claim 1, wherein the reference signal configuration message for instructing the distribution unit to send the corresponding reference signal comprises related reference signal parameters; the related reference signal parameters comprise at least one of a transmission period, a subframe offset and a resource element pattern; the subframe offset is used for indicating which subframes in the transmission period transmit corresponding reference signals, and the resource unit pattern is used for indicating the mapping mode of the corresponding reference signals to the resource units.

4. The method of claim 3, wherein the resource element pattern is of a CSI-RS class or a CRS class.

5. The method of any of claims 1-4, wherein determining whether to turn on or off distribution units within the coverage area of the central unit comprises:

the central unit selecting at least one access distribution unit within the coverage area of the central unit; and

sending the reference signal configuration message to the distribution unit comprises:

transmitting the reference signal configuration message to the at least one access distribution unit in an off mode to cause the at least one access distribution unit to start transmitting a corresponding reference signal.

6. The method of claim 5, wherein the reference signal configuration message comprises a subframe offset; the subframe offset is mainly used by all distribution units which currently send reference signals.

7. The method of claim 5, wherein selecting the at least one access distribution unit within the coverage area of the central unit comprises:

selecting the at least one access distribution unit within the coverage area based at least on the distribution of the distribution units to enable a transmission range of reference signals of the at least one access distribution unit to cover the coverage area of the central unit.

8. The method of claim 7, wherein selecting the at least one access distribution unit within the coverage area of the central unit further comprises:

selecting the at least one access distribution unit only among the switched-off distribution units.

9. The method of claim 5, wherein selecting the at least one access distribution unit within the coverage area of the central unit further comprises:

selecting the at least one access distribution unit within the coverage area in response to a distribution unit access request from a user equipment.

10. The method of claim 9, further comprising:

sending the list of the at least one access distribution unit and the related reference signal parameters to the user equipment.

11. The method of any of claims 1-4, wherein determining whether to turn on or off distribution units within the coverage area of the central unit comprises:

determining whether to start the distribution unit in the coverage area according to the information of the first distribution unit by the central unit; wherein the first distribution unit is a distribution unit initially connected to at least one user equipment; and

transmitting a reference signal configuration message to distribution units within the coverage area comprises:

the central unit sends a first reference signal configuration message to the first distribution unit and sends a second reference signal configuration message to at least one closed distribution unit among distribution units adjacent to the first distribution unit.

12. The method of claim 11, wherein the first reference signal configuration message and the second reference signal configuration message each comprise a subframe offset; wherein the subframe offset included in the first reference signal configuration message is the same as a subframe offset used before the first distribution unit connects to the at least one user equipment, and the subframe offset included in the second reference signal configuration message is the same as the subframe offset included in the first reference signal configuration message.

13. The method of any of claims 1-4, wherein determining whether to turn on or off distribution units within the coverage area of the central unit comprises:

the central unit determines whether to start a distribution unit in the coverage area according to user equipment switching information in the coverage area, wherein the switching information at least comprises information of a source distribution unit connected with the user equipment before switching and information of a target distribution unit connected with the user equipment after switching; and

transmitting a reference signal configuration message to the distribution units within the coverage area comprises:

when the source distribution unit is not connected with any user equipment after switching, the central unit sends a candidate reference signal configuration message to the source distribution unit; and when the target distribution unit is not connected with any user equipment before switching, the central unit sends a service reference signal configuration message to the target distribution unit.

14. The method of claim 13, wherein the candidate reference signal configuration message and the serving reference signal configuration message each include a subframe offset, and wherein the subframe offset included in the candidate reference signal configuration message and the subframe offset in the serving reference signal configuration message are the same as a subframe offset used before handover.

15. The method of any of claims 1-4, wherein determining whether to turn on or off distribution units within the coverage area of the central unit comprises:

the central unit determines whether to close the distribution units in the coverage area according to the information of the distribution units to be closed, wherein the distribution units to be closed comprise the distribution units set to be closed, all candidate distribution units of which all adjacent distribution units are in a non-service mode, all connected user equipment become idle state or all service distribution units switched to the coverage areas of other central units; and

and the central unit sends the reference signal configuration message to the distribution unit to be closed so as to enable the distribution unit to be closed to stop sending the reference signal to enter a closing mode.

16. The method according to any of claims 1-4, wherein the central unit is a dedicated baseband processing unit, a centralized radio access network server, a cloud server, or a virtual base station based on a cloud-framed baseband pool; the distribution unit is a transmission point, a receiving and transmitting point or a radio remote head.

17. A method for reference signal configuration, comprising:

a distribution unit receives a reference signal configuration message from a central unit, wherein the central unit is connected with and controls a plurality of the distribution units; the central unit bears the upper layer in the air interface protocol stack, and the distribution unit bears the lower layer of the air interface protocol stack; and

the distribution unit switches from stopping sending the reference signal to sending the corresponding reference signal or stops sending the reference signal in response to the reference signal configuration message.

18. The method of claim 17, wherein the reference signal configuration message for instructing the distribution unit to stop sending reference signals comprises: a cell for controlling the distribution unit to stop sending reference signals to enter a shutdown mode.

19. The method of claim 17, wherein the reference signal configuration message for instructing the distribution unit to send the corresponding reference signal comprises related reference signal parameters; the related reference signal parameters comprise at least one of a transmission period, a subframe offset and a resource element pattern; the subframe offset is used for indicating which subframes in the transmission period transmit corresponding reference signals, and the resource unit pattern is used for indicating the mapping mode of the corresponding reference signals to the resource units.

20. The method of claim 19,

the resource unit patterns are CSI-RS type or CRS type.

21. The method according to any one of claims 17-20, further comprising:

the distribution unit sends a list of distribution units to be tested and related reference signal parameters to user equipment, wherein the list of the distribution units to be tested comprises access distribution units or distribution units adjacent to the distribution units.

22. A central unit, comprising:

a determining module for determining whether to turn on or off a distribution unit within a coverage area of the central unit, wherein the central unit connects and controls a plurality of the distribution units; the central unit bears the upper layer in the air interface protocol stack, and the distribution unit bears the lower layer of the air interface protocol stack; and

a sending module, configured to send a reference signal configuration message to the distribution unit, so that the distribution unit switches from stopping sending the reference signal to sending the corresponding reference signal or stops sending the reference signal in response to the reference signal configuration message.

23. The central unit of claim 22, wherein the determining module is configured to select at least one access distribution unit within the coverage area of the central unit; and

the sending module is configured to send the reference signal configuration message to the at least one access distribution unit in the shutdown mode, so that the at least one access distribution unit starts sending a corresponding reference signal.

24. The central unit according to claim 22, wherein the determining module is configured to determine whether to turn on a distribution unit in the coverage area according to information of a first distribution unit; wherein the first distribution unit is a distribution unit initially connected to at least one user equipment; and

the sending module is configured to send a first reference signal configuration message to the first distribution unit, and send a second reference signal configuration message to at least one closed distribution unit in distribution units adjacent to the first distribution unit.

25. The central unit according to claim 22, wherein the determining module is configured to determine whether to turn on a distribution unit according to handover information of a ue in the coverage area, wherein the handover information includes at least information of a source distribution unit connected to the ue before handover and information of a target distribution unit connected to the ue after handover;

the sending module is configured to send a candidate reference signal configuration message to the source distribution unit when the source distribution unit is not connected to any user equipment after being switched; and when the target distribution unit is not connected with any user equipment before switching, sending a service reference signal configuration message to the target distribution unit.

26. The central unit according to claim 22, wherein the determining module is configured to determine whether to turn off the distribution units in the coverage area according to information of the distribution units to be turned off, wherein the distribution units to be turned off include a distribution unit set to be turned off, a candidate distribution unit in which all neighboring distribution units are in a non-service mode, a service distribution unit in which all connected user equipments become idle or switch to coverage areas of other central units; and

the sending module is configured to send the reference signal configuration message to the distribution unit to be closed, so that the distribution unit to be closed stops sending the reference signal to enter a closing mode.

27. A distribution unit, comprising:

a receiving module for receiving a reference signal configuration message from a central unit, wherein the central unit is connected to and controls a plurality of the distribution units; the central unit bears the upper layer in the air interface protocol stack, and the distribution unit bears the lower layer of the air interface protocol stack; and

and the response module is used for responding to the reference signal configuration message and switching from the reference signal transmission stopping to the corresponding reference signal transmission or stopping the reference signal transmission.

28. The distribution unit of claim 27, wherein the reference signal configuration message for instructing the distribution unit to stop sending reference signals comprises: a cell for controlling the distribution unit to stop sending reference signals to enter a shutdown mode.

29. The distribution unit according to claim 27, wherein the reference signal configuration message for instructing the distribution unit to transmit the corresponding reference signal comprises the relevant reference signal parameters; the related reference signal parameters comprise at least one of a transmission period, a subframe offset and a resource element pattern; the subframe offset is used for indicating which subframes in the transmission period transmit corresponding reference signals, and the resource unit pattern is used for indicating the mapping mode of the corresponding reference signals to the resource units.

30. The distribution unit of claim 29, wherein the resource element pattern is CSI-RS or CRS.

31. The distribution unit of any one of claims 27-30, further comprising:

a sending module, configured to send a list of distribution units to be tested and related reference signal parameters to user equipment, where the list of distribution units to be tested includes an access distribution unit or a distribution unit adjacent to the access distribution unit.

32. A central unit comprising a processor and a transceiver connected to the processor; the processor is configured to:

determining whether to turn on or off a distribution unit within a coverage area of the central unit; and

transmitting, by the transceiver, a reference signal configuration message to the distribution unit to cause the distribution unit to switch from stopping transmitting reference signals to transmitting corresponding reference signals or to stop transmitting reference signals in response to the reference signal configuration message;

wherein the central unit is connected to and controls a plurality of the distribution units; the central unit carries a higher layer in an air interface protocol stack and the distribution unit carries a lower layer of the air interface protocol stack.

33. The central unit of claim 32, wherein the reference signal configuration message for instructing the distribution units to stop sending reference signals comprises: a cell for controlling the distribution unit to stop sending reference signals to enter a shutdown mode.

34. The central unit according to claim 32, wherein the reference signal configuration message instructing the distribution units to send corresponding reference signals comprises related reference signal parameters; the related reference signal parameters comprise at least one of a transmission period, a subframe offset and a resource element pattern; the subframe offset is used for indicating which subframes in the transmission period transmit corresponding reference signals, and the resource unit pattern is used for indicating the mapping mode of the corresponding reference signals to the resource units.

35. The central unit of claim 34, wherein the resource element pattern is CSI-RS or CRS-like.

36. The central unit according to any of claims 32-35, wherein the processor is configured to: selecting at least one access distribution unit within the coverage area of the central unit; and transmitting, by the transceiver, the reference signal configuration message to the at least one access distribution unit in an off mode to cause the at least one access distribution unit to start transmitting a corresponding reference signal.

37. The central unit according to claim 36, wherein the reference signal configuration message comprises a subframe offset; the subframe offset is mainly used by all distribution units which currently send reference signals.

38. The central unit of claim 36, wherein the processor is configured to: selecting the at least one access distribution unit within the coverage area based at least on the distribution of the distribution units to enable a transmission range of reference signals of the at least one access distribution unit to cover the coverage area of the central unit.

39. The central unit of claim 36, wherein the processor is configured to: selecting the at least one access distribution unit only among the switched-off distribution units.

40. The central unit of claim 36, wherein the processor is configured to: selecting the at least one access distribution unit within the coverage area in response to a distribution unit access request from a user equipment.

41. The central unit of claim 40, wherein the processor is further configured to: sending, by the transceiver, the list of the at least one access distribution unit and the associated reference signal parameters to the user equipment.

42. The central unit according to any of claims 32-35, wherein the processor is configured to:

determining whether to start a distribution unit in the coverage area according to the information of the first distribution unit; wherein the first distribution unit is a distribution unit initially connected to at least one user equipment; and

transmitting, by the transceiver, a first reference signal configuration message to the first distribution unit and a second reference signal configuration message to at least one closed distribution unit among distribution units adjacent to the first distribution unit.

43. The central unit according to claim 42, wherein the first and second reference signal configuration messages each comprise a subframe offset; wherein the subframe offset included in the first reference signal configuration message is the same as a subframe offset used before the first distribution unit connects to the at least one user equipment, and the subframe offset included in the second reference signal configuration message is the same as the subframe offset included in the first reference signal configuration message.

44. The central unit according to any of claims 32-35, wherein the processor is configured to:

determining whether to start a distribution unit in the coverage area according to user equipment switching information in the coverage area, wherein the switching information comprises at least information of a source distribution unit connected with the user equipment before switching and information of a target distribution unit connected with the user equipment after switching; and

when the source distribution unit is not connected with any user equipment after being switched, sending a candidate reference signal configuration message to the source distribution unit through the transceiver, and sending a service reference signal configuration message to the target distribution unit when the target distribution unit is in a candidate mode before being switched.

45. The central unit according to claim 44, wherein the candidate reference signal configuration message and the serving reference signal configuration message each comprise a subframe offset, and wherein the subframe offset included in the candidate reference signal configuration message and the subframe offset in the serving reference signal configuration message are the same as the subframe offset used before the handover.

46. The central unit according to any of claims 32-35, wherein the processor is configured to:

determining whether to close the distribution units in the coverage area according to the information of the distribution units to be closed, wherein the distribution units to be closed comprise distribution units set to be closed, candidate distribution units with all adjacent distribution units in a non-service mode, and service distribution units with all connected user equipment becoming idle or switching to the coverage areas of other central units; and

and sending the reference signal configuration message to the distribution unit to be closed through the transceiver so as to enable the distribution unit to be closed to stop sending the reference signal to enter a closing mode.

47. The central unit according to any of claims 32-35, wherein the central unit is a dedicated baseband processing unit, a centralized radio access network server, a cloud server, or a virtual base station based on a cloud-based baseband pool; the distribution unit is a transmission point, a receiving and transmitting point or a radio remote head.

48. A distribution unit, comprising: a processor and a transceiver connected to the processor; the processor is configured to:

receiving, by the transceiver, a reference signal configuration message from a central unit; and

switching from stopping transmitting reference signals to transmitting corresponding reference signals or stopping transmitting reference signals in response to the reference signal configuration message;

wherein the central unit connects and controls a plurality of the distribution units; the central unit carries a higher layer in an air interface protocol stack and the distribution unit carries a lower layer of the air interface protocol stack.

49. The distribution unit of claim 48, wherein the reference signal configuration message for instructing the distribution unit to stop sending reference signals comprises: a cell for controlling the distribution unit to stop sending reference signals to enter a shutdown mode.

50. The distribution unit according to claim 48, wherein the reference signal configuration message instructing the distribution unit to send the corresponding reference signal comprises the relevant reference signal parameters; the related reference signal parameters comprise at least one of a transmission period, a subframe offset and a resource element pattern; the subframe offset is used for indicating which subframes in the transmission period transmit corresponding reference signals, and the resource unit pattern is used for indicating the mapping mode of the corresponding reference signals to the resource units.

51. The distribution unit of claim 50, wherein the resource element pattern is of a CSI-RS class or a CRS class.

52. The distribution unit of any one of claims 48-51, wherein the processor is further configured to: and sending a list of distribution units to be tested and related reference signal parameters to user equipment, wherein the list of the distribution units to be tested comprises access distribution units or distribution units adjacent to the distribution units.